The present application claims priority from U.S. patent application Ser. Nos. 17/944,910, 17/944,900, and 17/944,905, filed on 9.2022, and 14, each of which is incorporated herein by reference in its entirety.
Detailed Description
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, like numerals generally identify like components unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized and other changes may be made without departing from the spirit or scope of the subject matter described herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are contemplated and form part of this disclosure.
The present disclosure relates, at least in part, to systems and methods that provide reduced operating costs, improved efficiency, and/or improved performance of dual fuel engine systems. In some embodiments, such systems and methods allow for meeting a target emission level. In some embodiments, the scheme for controlling the dual fuel system is adjustable to simplify the connections (interfacing) between, for example, the diesel engine ECM, the gas controller, and the OEM controller. In various embodiments, the dual fuel engine system (and associated operating methods) is tailored to maximize the use of less expensive gaseous fuel and minimize the use of diesel fuel while meeting performance and emissions requirements and maintaining robust engine protection. In particular, in order to meet Tier 4 emission regulations with dual fuel engine systems, precise and robust control of the dual fuel engine system is required. Such precise and robust control includes, but is not limited to, control of a gaseous or liquid fuel system, a second fuel type system (e.g., diesel, gas, etc.), and an aftertreatment system included within a dual fuel engine system. The present disclosure outlines a system and method for precise and robust control of a dual fuel engine system, including accurately determining (e.g., by measurement or estimation) a plurality of engine parameters (e.g., braking power, friction power, accessory power, first fuel (e.g., diesel, gas, liquid fuel) power, second fuel (e.g., gas, liquid) substitution rate, fuel quality parameters associated with the second fuel (e.g., methane value), LHV, second fuel (e.g., gas, liquid) temperature, second fuel (e.g., gas, liquid) pressure, knock intensity, exhaust temperature, etc.), and using the determined parameters as inputs for determining appropriate commands for one or more actuators within the dual fuel engine system. The systems and methods described herein are applicable to new engine configurations or for retrofitting to existing Tier 4 diesel engine systems. Advantageously, the systems and methods described herein are lower in cost and complexity than typical port gas injection or cylinder pressure sensing systems.
Referring to fig. 1, a block diagram of a dual fuel engine system 10 is shown in accordance with an exemplary embodiment. The dual fuel engine system 10 is configured as an engine having dual fuel modes of operation configured to operate using two different fuels. The engine may be configured to operate using a first fuel and a second fuel, wherein the first fuel and the second fuel have different properties and/or chemical compositions. These characteristics may include autoignition temperature, flame speed, etc. The fuel may include, for example, diesel and natural gas. For example, the first fuel may be diesel fuel. The second fuel may be, for example, natural gas, an electric fuel (e-fuel), or a liquid biofuel. The liquid biofuel may be, for example, methanol and/or ethanol. The first fuel or the second fuel may be any of a high cetane number fuel (HIGH CETANE number fuel), such as diesel, gas-to-liquid (GTL) diesel, heavy Fuel Oil (HFO), low sulfur fuel oil (LFSO), hydrotreated Vegetable Oil (HVO), marine light diesel (MGO), renewable diesel, biodiesel, paraffinic diesel, dimethyl ether (DME), F-76 fuel, F-34 fuel, jet a fuel, JP-4 fuel, JP-8 fuel, or formaldehyde ether (OME) or low cetane number fuel (e.g., high octane fuel, high methane number fuel). The low cetane fuel may be natural gas, hydrogen, ethane, propane, butane, syngas, ammonia, methanol, ethanol, or gasoline. The first fuel and/or the second fuel may optionally be a mixture of fuels. It should be appreciated that the foregoing is merely an example of a fuel and does not exclude other types of first and second fuels. In various embodiments, the dual fuel engine system 10 is configured for one or more oil and gas production applications (e.g., land-based oil and/or gas drilling and hydraulic fracturing).
As shown in fig. 1, the dual fuel engine system includes an internal combustion engine 20, the internal combustion engine 20 being operatively coupled to the control system 11 via at least one controller 18. The control system 11, including the machine control system (OEM system) 12, the first fuel control system 14, and the second fuel control system 16, is configured to send one or more inputs to the controller 18, where the controller 18 then controls the internal combustion engine 20. In various embodiments, the first fuel control system 14 and its components are configured to operate using a first fuel. In other embodiments, the second fuel control system 16 and its components are configured to operate using a second fuel. For example, in various embodiments, the first fuel control system 14 is a diesel control system and the second fuel control system 16 is a gas control system. In other embodiments, the first fuel control system 14 is a first gas control system and the second fuel control system 16 is a second gas control system. In still other embodiments, one or both of the first fuel control system 14 and the second fuel control system 16 may be liquid fuel control systems.
In still other embodiments, the first fuel control system 14 and its components are configured to operate with the second fuel, and the second fuel control system 16 and its components are configured to operate with the first fuel. In still other embodiments, each of the first and second fuel control systems 14, 16 and their respective components may be selectively operated using either the first fuel or the second fuel. In various embodiments, the first fuel control system 14 and the second fuel control system 16 operate cooperatively within the internal combustion engine 20.
In various embodiments, the controller 18 is configured to include a processor and a non-transitory computer-readable medium (e.g., a memory device) having computer-readable instructions stored thereon that, when executed by the processor, cause at least one controller 18 to perform one or more operations. In various embodiments, at least one controller 18 is a computing device (e.g., a microcomputer, microcontroller, or microprocessor). In other embodiments, the at least one controller 18 is configured as part of a data cloud computing system configured to receive commands from a user control device and/or a remote computing device.
The following description relates generally to a system in which the first fuel control system 14 operates using a first fuel and the second fuel control system 16 operates using a second fuel, however, it should be appreciated that in other embodiments, each of the first fuel control system 14 and the second fuel control system 16 may be selectively configured to operate using either the first fuel or the second fuel as described above. The controller 18 is also operatively coupled to at least one second fuel injector 28 (to facilitate injection of a second fuel), at least one second fuel heater 32 configured to heat the second fuel, and at least one actuator 33. In some embodiments, the second fuel injector 28 is a gas injector. In other embodiments, the second fuel injector 28 is a liquid fuel injector. In various embodiments, the at least one second fuel heater 32 is a gas heater configured to heat a gas. In some embodiments, the at least one second fuel heater 32 is a liquid fuel heater configured to heat liquid fuel. In other embodiments, the dual fuel engine system 10 does not include a second fuel heater. In some embodiments, each of the second fuel injector 28, the heater 32, and the actuator 33 are operatively coupled to the internal combustion engine 20. In various embodiments, the second fuel injector 28 is configured to control or facilitate injection of a second fuel (e.g., a gas or liquid, or a second gas) into the internal combustion engine 20. The at least one second fuel heater 32 is configured to adjust a temperature of the second fuel flowing within the internal combustion engine 20. The actuators 33 may include one or more first fuel type (e.g., diesel type or other liquid type, first gas type) actuators, air handling actuators, aftertreatment actuators, or any other type of actuator within the dual fuel engine system 10. Thus, during operation, the controller 18 may send one or more inputs to one or more of the internal combustion engine 20, the second fuel injector 28, the heater 32, or the actuator 33 to facilitate a desired operating mode of the dual fuel engine system 10.
As shown, the internal combustion engine 20 includes an output shaft 24 and may also include one or more accessories 22. The internal combustion engine 20 also includes at least one manifold 26. In various embodiments, at least one manifold 26 includes, but is not limited to, an intake manifold. The internal combustion engine 20 also includes at least one engine cylinder bank. In some embodiments, at least one engine cylinder group includes a left group (left bank) 30 and a right group (right bank) 31. During operation of the dual fuel engine system 10, the control system 11 may receive one or more inputs from a user and/or one or more sensors within the dual fuel engine system 10 and control operation of at least one of the internal combustion engine 20, the second fuel injector 28, or the actuator 33 via the controller 18.
Fig. 2 is a block diagram of a control system 11 of the dual fuel engine system 10, according to an exemplary embodiment. As shown, OEM system 12 may include one or more sensors 35, each of the one or more sensors 35 coupled to one or more corresponding components within dual engine system 10. In various embodiments, one or more sensors 35 may be operably coupled to or in communication with a frac ("frac") pump, an accessory, one or more inlets or outlets of the internal combustion engine 20, or any other component within the dual fuel engine system 10 (e.g., cooling fan, flywheel, brake, etc.). The OEM system 12 may include one or more processors configured to receive input from the sensors 35. In various embodiments, the one or more inputs from the sensor 35 may include a power estimate, a frac pump speed, a frac pump discharge pressure, a dual fuel mode activation request, or any other input detectable by the one or more sensors 35. As shown, the OEM system 12 may be communicatively coupled to each of the first and second fuel control systems 14, 16, wherein the OEM system 12 may output information sensed by one or more sensors 35 or may receive input from the first and/or second fuel control systems 14, 16.
As shown in fig. 2, the first fuel control system 14 includes one or more sensors 40, the one or more sensors 40 being coupled to one or more components within the internal combustion engine 20 or disposed adjacent to one or more components within the internal combustion engine 20. In various embodiments, one or more sensors 40 may be configured to determine (e.g., sense, detect, measure) at least one of an engine speed, an intake manifold temperature, an engine coolant temperature, an oil temperature, a cooling fan duty cycle, a first fuel (e.g., diesel, first gas, or other liquid) rate, or an operating state of the dual fuel mode switch 55. In various embodiments, the dual fuel mode switch 55 may be configured to switch operation of the internal combustion engine 20 between a single fuel mode or a dual fuel mode. Additionally or alternatively, one or more sensors 40 may be configured to determine a Lower Heating Value (LHV) of the second fuel (e.g., gas, liquid, or second gas). In still other embodiments, the one or more sensors 40 may be configured to determine one or more parameters indicative of LHV, which may include, but are not limited to, a second fuel (e.g., gas, liquid, or second gas) density or speed of sound. The first fuel control system 14 also includes an engine governor 50. In various embodiments, the engine governor 50 may include one or more controllers configured to control the rotational speed of the internal combustion engine 20.
The first fuel (e.g., diesel or first gas) control system 14 also includes a first fuel (e.g., diesel or first gas) engine control system (ECM) and a torque fueling calculation module (torque fueling calculations module) 45. In various embodiments, the torque fueling calculation module 45 may include one or more processors in communication with one or more reference databases or reservoirs, wherein the one or more processors are configured to reference data stored within the databases in order to perform torque calculations associated with the internal combustion engine 20. For example, in various embodiments, the torque fueling calculation module 45 is configured to calculate the torque based on one or more known parameters. In various embodiments, module 45 is configured to receive inputs corresponding to dual fuel mode operating conditions, engine friction parameters, accessory ("parasitic") torque parameters, engine speed, OEM machine power estimates, and engine accessory power estimates (e.g., gas controller, liquid fuel controller, flywheel, etc.). In various embodiments, one or more reference databases or repositories may include a lookup table 65. In various embodiments, the one or more lookup tables 65 include one or more chi-square tables. In various embodiments, the lookup table 65 may include reference information related to engine torque, engine speed, engine friction parameters, parasitic or accessory torque parameters, fuel rate (fuel rate) of the first fuel (e.g., diesel or first gas), intake manifold temperature, and/or engine coolant temperature. In various embodiments, the engine friction parameters of the lookup table 65 may be based on at least one of an oil temperature or a coolant temperature. In some embodiments, the parasitic parameter or torque parameter of the lookup table 65 may be based on a cooling fan duty cycle (i.e., a cooling fan duty cycle of a cooling fan within the internal combustion engine 20). In various embodiments, the module 45 is configured to determine at least one of a total fuelling amount (fueling amount) of a first fuel (e.g., diesel or first gas), an approximately equivalent total fuelling amount, an equivalent total fuelling amount (i.e., fuelling equivalent of a second fuel of the fuelling amount of the first fuel), a friction torque estimate, or a first fuel rate.
The first fuel control system 14 also includes a first fuel (e.g., diesel or first gas) air treatment, aftertreatment, and fuel system reference determination and control module 60. In various embodiments, the control module 60 may include at least one processor in communication with a database (e.g., a lookup table) 75. In various embodiments, database 75 includes a data repository relating to engine speed, fueling amount (e.g., equivalent total fueling amount, approximately equivalent total fueling amount), secondary fuel (e.g., gas, liquid, or secondary gas) substitution rate (G/D), compressor Inlet Density (CID), or any other relevant parameter. Accordingly, the one or more processors within the control module 60 are configured to reference the data stored within the database 75 to determine one or more system inputs for at least one of the air treatment control system 80, the aftertreatment control system 85, or the first fuel control system 90. In various embodiments, the one or more system inputs include, but are not limited to, actuator commands or targets (e.g., set points, operating thresholds, etc.) for at least one of the first fuel air process control system 80, the aftertreatment control system 85, or the first fuel control system 90.
As shown in fig. 2, the second fuel (e.g., gas, liquid, or second gas) control system 16 may include one or more sensors 95, the one or more sensors 95 coupled to one or more components within the internal combustion engine 20 or disposed adjacent to one or more components within the internal combustion engine 20. In various embodiments, one or more sensors 95 may be configured to determine (e.g., sense, detect, measure, etc.) at least one of OEM machine torque, accessory torque, a fuel quality parameter associated with a second fuel, a second fuel injector pressure, a second fuel supply pressure, a second fuel flow, an engine block exhaust temperature, an aftertreatment system temperature, LHV, a second fuel temperature, a dual fuel mode input, knock intensity, G/D, or any other relevant parameter. In various embodiments, the fuel quality parameter associated with the second fuel may be a knock tendency indicator (knock propensity indicator) or a knock tendency index. In some embodiments, the knock tendency index (KPI) may be an index that relates the fuel composition (i.e., of the second fuel) to the knock tendency of an engine (i.e., engine 20) operating with the fuel (i.e., the second fuel). In some embodiments, the KPI may be a Methane Number (MN), an octane number, an antiknock index (AKI), or any other parameter known in the art. In various embodiments, when the second fuel is natural gas, the KPI may be MN. In various embodiments, when the second fuel is gasoline, the KPI may be an octane number or AKI. In some embodiments, the engine block exhaust temperature may correspond to a left set of average exhaust temperatures and/or a right set of average exhaust temperatures. In some embodiments, the group average exhaust temperature may be calculated by averaging measurements from the various exhaust port temperature sensors. In some embodiments, the exhaust port temperature sensor may be in at least one of the sensors 35, 40, and/or 95. The second fuel control system 16 also includes an OEM machine power and accessory power estimation module 130. In various embodiments, the OEM machine power and accessory power estimation module 130 may include one or more processors configured to estimate OEM machine power and/or accessory power based on one or more inputs received by the one or more sensors 95 (and/or from the sensors 35, 40). in some embodiments, the accessory power may be power associated with one or more accessory components and/or an output shaft (e.g., output shaft 24) within the dual fuel engine system 10. In various embodiments, the OEM machine power and accessory power estimation module 130 is configured to receive inputs related to the OEM machine power estimate, the accessory torque measurement, the pump speed, the pump discharge pressure, and the engine speed, wherein the one or more processors then estimate the accessory power estimate based on the inputs. Similarly, the second fuel control system 16 also includes a KPI (e.g., MN) estimation module 125. In various embodiments, the KPI estimation module 125 may include one or more processors configured to estimate a KPI associated with the internal combustion engine 20 based on one or more inputs received by the one or more sensors 95 (and/or from the sensors 35, 40). In various embodiments, at least one of the sensors 35, 40, or 95 may be assigned or partitioned to any of the different control systems (e.g., OEM system 12, first fuel control system 14, second fuel control system 16) within the dual fuel engine system 10 without changing the overall function of the sensor. For example, in various embodiments, the sensor 95 may be included within or operatively coupled to any of the OEM system 12, the first fuel control system 14, or the second fuel control system 16. Similarly, the sensor 35 may be included within or operatively coupled to any of the OEM system 12, the first fuel control system 14, or the second fuel control system 16. The sensor 40 may also be included within or operatively coupled to any of the OEM system 12, the first fuel control system 14, or the second fuel control system 16.
The second fuel control system 16 also includes an indication engine power (INDICATED ENGINE power) and a second fuel (e.g., gas, liquid, or second gas) estimation module 115. The engine power and second fuel estimation module 115 may include one or more processors configured to receive one or more inputs related to the operation of the dual fuel engine system 10. The engine power and second fuel estimation module 115 may also be configured to determine at least one of a thermal efficiency estimate, a first power estimate of a second fuel (e.g., gas, liquid, or second gas), an indicated power estimate of a first fuel (e.g., diesel, first gas, or other liquid), a net engine power estimate, an intake manifold temperature (e.g., maximum intake manifold temperature), and/or other relevant parameters using a database 170 and/or a torque-to-power computing system (torque-power calculation system) 175. In various embodiments, database 170 is a lookup table. In some embodiments, the torque-to-power computing system 175 may be or include computer logic. In various embodiments, the engine power and second fuel estimation module 115 is configured to receive one or more inputs corresponding to a G/D estimation, a friction torque estimation, an accessory ("parasitic") torque estimation, a first fuel rate, an engine speed, an intake manifold temperature, and/or an MN estimation. In an embodiment, the KPI estimate is determined by KPI module 125. Although the terms "torque" and "power" are used throughout this disclosure in various instances, it should be understood that in various embodiments, torque may be used instead of power, or power may be used instead of torque. For example, it should be appreciated that power may be calculated based on torque and rotational speed, and vice versa. In still other embodiments, any other parameter indicative of load (e.g., alternatively or in addition to torque and/or power) may be determined and/or used in the operations performed by the control system 11.
The second fuel control system 16 also includes a second fuel (e.g., gas, liquid, or second gas) LHV and G/D estimation module 120. The LHV and G/D estimation module 120 may include a second fuel (e.g., gas, liquid, or second gas) power selector switch 185, an LHV learning algorithm 180 configured to process one or more received inputs, and a power rationality diagnostic and protection module 190. In various embodiments, LHV learning algorithm 180 includes a filter (e.g., a low pass filter, a moving average filter, etc.) and/or an adaptive learning routine. In some embodiments, one or more inputs are received from sensor 95. LHV and G/D estimation module 120 may include one or more processors configured to receive inputs including a total flow estimate of a second fuel (i.e., of the second fuel flowing within engine system 10), a thermal efficiency estimate, an indicated power estimate of a first fuel, and a first indicated engine power estimate. In various embodiments, one or more processors of LHV and G/D estimation module 120 may receive input from sensors 35, 40, and/or 95. The LHV and G/D estimation module 120 may thereby estimate the amount of G/D and the amount of LHV associated with the internal combustion engine 20. In various embodiments, one or more processors within LHV and G/D estimation module 120 may determine the LHV and G/D estimates by multiplying a total flow estimate of the second fuel by a thermal efficiency estimate and using the result to normalize a first power estimate of the second fuel (e.g., by dividing the first power estimate of the second fuel by a product of the total flow estimate of the second fuel and the thermal efficiency estimate) to determine the instantaneous LHV amount. The LHV learning algorithm 180 may process the instantaneous LHV quantity to then determine (i.e., learn) the LHV estimate. In various embodiments, the second fuel power selector switch 185 may be configured to receive inputs corresponding to the first power estimate and the second power estimate. In some embodiments, the second fuel power selector switch 185 may also be configured to output a final power estimate of the second fuel using the first power estimate and the second power estimate. In various embodiments, the final power estimate of the second fuel is based on a maximum or minimum of the first power estimate and the second power estimate. In various embodiments, the power rationality diagnostic and protection module 190 may include one or more processors configured to receive inputs corresponding to the first indicated engine power estimate and the second indicated engine power estimate. In some embodiments, the power rationality diagnostic and protection module 190 is further configured to initiate one or more diagnostic operations or engine protection protocols based on and in response to a comparison of one or both of the first indicated engine power estimate and the second indicated engine power estimate to one or more thresholds.
As shown, the second fuel control system 16 also includes a G/D target auto-compensation module 105. In various embodiments, the G/D target auto-compensation module 105 is configured to adjust or compensate for the G/D target of the internal combustion engine 20. The module 105 is configured to receive one or more inputs indicative of engine speed, engine load (e.g., power, torque, etc.), intake manifold temperature, and/or KPI estimates. In various embodiments, module 105 receives one or more inputs from sensors 95, 35, and/or 40. In some embodiments, one or more inputs received by module 105 are processed by a speed-based G/D target interpolation unit 135 to determine a G/D target based on the indicated engine speed. In various embodiments, the speed-based G/D target interpolation unit 135 uses data stored in one or more databases 145 to determine the G/D target based on the indicated engine speed. In some embodiments, one or more databases 145 may include one or more lookup tables. The module 105 also includes a G/D target limiter 140, the G/D target limiter 140 including one or more processors configured to determine a G/D target limit value based on one or more inputs. In various embodiments, the one or more inputs may include engine knock, exhaust temperature, and/or first fuel quantity. In various embodiments, the exhaust temperature corresponds to an exhaust temperature of an engine block. The second fuel control system 16 may use the G/D target limit value and the first indicated engine power estimate to determine a second fuel power target value.
As shown in FIG. 2, the second fuel control system 16 includes a second fuel injector control module 110, the second fuel injector control module 110 including at least one G/D proportional-integral-derivative (PID) controller 150. In various embodiments, the PID controller 150 is configured to receive a feed-forward input based on the second fuel injector pressure and temperature compensated second fuel flow target. In various embodiments, the second fuel injector pressure and temperature may be measured by sensors 95, 35, and/or 40. The controller 150 may also receive feedback inputs corresponding to the G/D estimates and target inputs corresponding to the G/D controller. In response to receiving the feed forward input, the feedback input, and the target input, the PID controller 150 can output at least one primary second fuel injector command. In various embodiments, at least one base second fuel injector command is associated with at least one engine block second fuel injector command. In some embodiments, the at least one engine block second fuel injector command includes a left set of second fuel injector commands and/or a right set of second fuel injector commands.
The second fuel injector command converter 160 may be operably coupled to the PID controller 150. In various embodiments, the second fuel injector command converter 160 may include one or more processors configured to convert the base second fuel injector command into at least one engine block second fuel injector command. The second fuel injector control module 110 may also include a group balancing PID controller 155. In various embodiments, the PID controller 155 is configured to receive feedback inputs corresponding to an exhaust temperature difference between a left group (e.g., left group 30) of the internal combustion engine 20 and a right group (e.g., right group 31) of the internal combustion engine 20, and a target value associated with the exhaust temperature difference. In various embodiments, the target value is zero. In response to the feedback input and the target input, the PID controller 155 is configured to output a left group correction amount and a right group correction amount. In various embodiments, one or both of the left and right sets of correction amounts may be positive or negative. The output left and right set of correction amounts may each be added to a base second fuel injector command (e.g., output from PID 150), which second fuel injector command converter 160 may convert to corresponding left and right set of second fuel injector commands. The second fuel flow estimator 165 is configured to receive a second fuel pressure and a second fuel temperature and each of the left and right sets of second fuel injector commands. In various embodiments, the second fuel flow estimator 165 may include or be coupled to one or more processors within the module 110. In some embodiments, the second fuel pressure and/or the second fuel temperature is measured by sensors 95, 35, and/or 40. In various embodiments, the second fuel flow estimator 165 is configured to output a total second fuel flow estimate associated with the internal combustion engine 20 based on the left and right sets of second fuel injector commands, the second fuel pressure, and the second fuel temperature.
Finally, as shown in FIG. 2, the second fuel control system 16 includes a second fuel heater control module 100. In various embodiments, the second fuel heater control module 100 is configured to control an operating state of at least one heater 32 coupled to the internal combustion engine 20. In various embodiments, the second fuel heater control module 100 includes one or more processors configured to receive one or more inputs from the at least one controller 18 and/or from other components within the control system 11. The one or more processors within the second fuel heater control module 100 may be configured to cause the second fuel heater control module 100 to change the operating state of the at least one heater 32. In some embodiments, changing the operating state of the at least one heater 32 may include adjusting an operating setting of the heater control valve 195 to control the operating state of the at least one heater 32. In various embodiments, the at least one heater 32 may be an electric heater. In other embodiments, at least one heater 32 may be configured to provide heat using engine coolant.
In various implementations, the engine control system 11, including the OEM system 12, the first fuel control system 14, and the second fuel control system 16, may cooperate to control the dual fuel engine system 10. Fig. 3 shows a flow chart illustrating a method 300 of controlling the dual fuel engine system 10 according to an exemplary embodiment. In operation 305, the engine control system 11 estimates a total engine load (e.g., power, torque, etc.) of the internal combustion engine 20. In various embodiments, the OEM system 12 calculates the total engine load by determining a first load ("primary load") delivered by the engine (e.g., via a flywheel, frac pump load, etc.) and broadcasting the determined first load (e.g., via a data link) to the first fuel control system 12 and/or the second fuel control system 16. In embodiments where the OEM system 12 controls an accessory load ("secondary load"), such as a cooling fan load, within the dual fuel engine system 10, the OEM system 12 may estimate the accessory load, add the accessory load to the first load amount, and then broadcast a sum indicative of the total engine load to the systems 14 and/or 16 (e.g., via a data link). In operation 310, the control system 11 may determine a total fueling amount of the internal combustion engine 20. Then, in operation 315, the control system 11 may control the dual fuel engine system 10 using the total fueling amount determined in operation 310.
In various implementations, the control system 11 may estimate the total engine load (e.g., power, torque, etc.). In some implementations, the control system 11 estimates the total engine load in operation 305 by measuring the engine power in operation 320, estimating the power loss in operation 325, and determining a sum of the measured engine power and the estimated power loss in operation 330. In some embodiments, the estimated total engine load may be based on inputs received from the OEM system 12 (e.g., from one or more sensors, which may sense at least one of pump discharge pressure, rotational speed, current, or voltage) in response to or indicative of an external load. The OEM system 12 may then use the inputs (i.e., sensed information) to calculate the engine load. The OEM system 12 may then output the calculated load value to the second fuel control system 16 and/or the first fuel control system 14 using the data link signal and/or the analog signal (e.g., 4mA-20 mA). In some embodiments, the external load corresponds to at least one of a generator or a pump operably coupled to the internal combustion engine 20. In various implementations, the engine control system 11 may determine the total fueling amount in operation 310. In some implementations, the control system 11 determines the total fueling in operation 310 based at least in part on the measured engine speed 335 and the calculated indicated torque demand 340 of the governor. As shown in fig. 4, in various implementations, controlling the dual fuel engine system 10 in operation 315 may include determining an updated total fueling amount in operation 345 and at least one control input for the at least one actuator 33 in operation 350. In various embodiments, at least one actuator 33 may be a first fuel system actuator. In various implementations, the updated total fueling amount determined in operation 345 may be based on the determination of the operational status of the dual fuel mode switch 55 in operation 355. In various embodiments, the updated fueling amount determined in operation 345 includes a first updated fueling amount and a second updated fueling amount. In some embodiments, the first updated fueling amount corresponds to a maximum between the total fueling amount and a fuel command (fuel command) for a first fuel (e.g., diesel, first gas, or other liquid). In some embodiments, the second updated total fueling amount is determined by subtracting the fueling command for the first fuel from the first total updated fueling amount to determine a first fuel equivalent of the fueling amount of the second fuel and adding the first fuel equivalent fueling amount to the second fueling command for the first fuel.
In various implementations, determining the control input for the at least one actuator 33 (in operation 350) may be based on selecting a set of look-up tables. The information in the look-up table may then be referenced in determining the control input. The look-up table may contain information from one or more of the first fuel ECM and torque fueling calculation module 45, the first fuel air treatment, aftertreatment and fuel system reference determination and control module 60, and/or the indicated engine power and the second fuel power estimation module 115. The selection of the set of look-up tables may be performed in operation 360. In various embodiments, selecting the set of lookup tables in operation 360 includes determining a Compressor Inlet Density (CID) of the internal combustion engine 20. In some embodiments, selecting the set of look-up tables in operation 360 additionally or alternatively includes determining a G/D within the internal combustion engine 20. In other embodiments, selecting the set of lookup tables in operation 360 additionally or alternatively includes determining an operational state of the dual fuel mode switch 55. In some embodiments, selecting the set of lookup tables in operation 360 includes selecting at least one of an air handling reference table, a post-handling reference table, or a fueling reference table.
In various implementations, the control system 11 may determine a maximum amount between the total fueling amount (from operation 310) and the first fuel command for the first fuel. In various embodiments, a first fuel command for a first fuel is determined from the first fuel control system 14. In some embodiments, the control system 11 may be configured to determine a second updated total fueling amount. In various embodiments, the second updated fueling amount is determined by subtracting the first fuel command for the first fuel from the first updated total fueling amount to determine a first fuel equivalent of a fueling amount of a second fuel associated with the internal combustion engine and adding the first fuel equivalent of the fueling amount of the second fuel to the second fuel command for the first fuel to determine the second updated total fueling amount. In various embodiments, the control system 11 may determine the at least one actuator command based on at least one of the engine speed and the first updated total fueling amount or the second updated total fueling amount. In some embodiments, the at least one actuator command may be associated with at least one actuator within the air treatment control system 80, the aftertreatment control system 85, the first fuel control system 90, or the actuator 33.
In various embodiments, determining the total fueling amount in operation 310 may include referencing one or more torque-to-fuel look-up tables. In various embodiments, one or more torque-to-fuel look-up tables are determined or referenced from the first fuel ECM and torque fuelling calculation module 45. In various embodiments, the lookup table may be based on engine speed and an indication of a first fuel torque input (INDICATED FIRST fuel torque input). In some embodiments, the indication of the first fuel torque input may be determined by the sensor 35. In various embodiments, the indicated first fuel torque input determined in operation 310 is based on a sum of the friction power estimate and the engine speed torque demand. In some embodiments, the engine speed torque demand corresponds to a difference between the engine speed and a predetermined engine speed target. In various embodiments, control system 11 determines a power loss estimate in operation 325. In some embodiments, control system 11 determines the power loss estimate in operation 325 by estimating an amount of friction torque associated with internal combustion engine 20, estimating an amount of accessory torque, determining an amount of charge air pumping torque, and determining an engine speed. In various embodiments, engine speed is determined via sensors 35, 40, and/or 95. In various embodiments, the charge air pumping torque amount is an estimate of the pumping loss associated with the dual fuel engine system 10, where the pumping loss corresponds to the amount of work the engine performs to draw air into the engine to facilitate combustion and then expel the combustion products into the atmosphere. In some embodiments, charge air pumping torque may be measured using cylinder pressure data determined during engine development. In various embodiments, the data determined during engine development may be used to calibrate a pumping torque virtual sensor (i.e., operatively coupled to the OEM system 12, the first fuel control system 14, and/or the second fuel control system 16) configured to sense an amount of charge air pumping torque.
In some implementations, the friction torque estimate may be determined from a look-up table. In various embodiments, a lookup table is determined or referenced from the first fuelled ECM and torque fuelling calculation module 45. In some embodiments, the lookup table is based on engine speed and engine friction parameters. In some embodiments, the engine friction parameter may correspond to an oil temperature or a coolant temperature within the internal combustion engine 20 of the dual fuel engine system 10. In various embodiments, the control system 11 may be configured to determine the accessory torque estimate from a look-up table. In various embodiments, a lookup table is determined or referenced from the first fuelled ECM and torque fuelling calculation module 45. In some embodiments, the lookup table is based on engine speed and accessory torque parameters. In various embodiments, the accessory torque parameter may correspond to a cooling fan power amount (e.g., a measured or estimated value) or duty cycle commanded by the internal combustion engine 20 of the dual fuel engine system 10.
In various embodiments, the control system 11 is configured to determine a first fuel command for a first fuel from a torque-to-fuel look-up table. In various embodiments, a torque-to-fuel look-up table is determined or referenced from the first fuelled ECM and torque fuelling calculation module 45. In some embodiments, the torque-to-fuel look-up table is based on an engine speed (i.e., of the internal combustion engine 20) and a sum of the friction power estimate and the torque demand associated with the internal combustion engine 20. In various implementations, the torque demand is set by the engine governor 50.
In various embodiments, control system 11 may be configured to activate one or more protective measures associated with internal combustion engine 20. In some embodiments, the control system 11 is configured to activate one or more protective measures via the power rationality diagnostic and protection module 190. FIG. 5 illustrates a method 400 that may be implemented by the control system 11 to activate one or more engine protection measures. In operation 405, the control system 11 is configured to determine an amount of frictional power loss. In various implementations, the amount of frictional power loss may be determined by measuring the rotational speed of the internal combustion engine 20 in operation 425 and estimating the amount of frictional torque in operation 430. After determining the amount of frictional power loss in operation 405, control system 11 may determine the amount of accessory power loss in operation 410. In various embodiments, the amount of accessory power loss may be associated with a load applied through the OEM system 12 (e.g., cooling fan, pump, alternator, etc.) and/or any other accessory component within the internal combustion engine 20 or coupled to the internal combustion engine 20.
In various embodiments, the accessory power consumption amount may be based on the measured engine speed (determined in operation 425) and based on the estimated accessory torque amount determined in operation 435. Using the accessory power loss amount and the friction power loss amount, the control system 11 may estimate a net engine power amount in operation 415. In various embodiments, the net engine power amount may also be based on the amount of braking power (e.g., engine dynamometer measurements) determined by the control system 11 in operation 440. Using the estimated net engine power amount determined in operation 415, the control system 11 may estimate a first indicated engine power and a first power amount for the first fuel in operation 420. In various embodiments, control system 11 may also estimate the indicated first fuel power. In some embodiments, the control system 11 is configured to estimate the indicated first fuel power by multiplying the determined thermal efficiency correction amount by the determined first fuel power estimate.
In some embodiments, determining the first fuel power estimate includes using a first lookup table. In various embodiments, a first lookup table is determined or referenced from the first fuelled ECM and torque fuelling calculation module 45. In some embodiments, the first lookup table is based on a first fuel rate and an engine speed. In various embodiments, determining the thermal efficiency correction amount includes referencing a first set of look-up tables. In some embodiments, a first set of look-up tables is determined or referenced from the first fuelled ECM and torque fuelling calculation module 45. In various embodiments, the first set of look-up tables is based on the G/D of the internal combustion engine 20, KPIs associated with the internal combustion engine 20, and/or intake manifold temperatures within the internal combustion engine 20. In various embodiments, estimating the first power amount for the second fuel includes subtracting the indicated first fuel power from the indicated engine power.
Then, in operation 450, the control system 11 may estimate a second indicated engine power and a second amount of power for the second fuel. In various embodiments, the second total indicated engine power and the second power amount of the second fuel may be based at least in part on the second fuel LHV value determined in operation 445. In various embodiments, the LHV determined in operation 45 may be based on the first power amount of the second fuel (determined in operation 420), the total second fuel flow estimate, and the thermal efficiency correction amount. In some implementations, LHV may be determined by an estimate. In various embodiments, control system 11 may determine the LHV estimate by dividing the first power amount of the second fuel by a multiple of the second fuel flow estimate and the thermal efficiency correction amount. In various implementations, the resulting LHV is an instantaneous LHV amount. In some embodiments, the control system 11 may be configured to implement a learning algorithm to determine the LHV estimate from the instantaneous LHV quantity.
In other embodiments, the second total indicated engine power and the second power amount of the second fuel may additionally or alternatively be based on the estimated engine second fuel flow (determined in operation 453) and the estimated first fuel power amount (determined in operation 455). In various embodiments, determining the second total indicated engine power includes determining a product of the total second fuel flow estimate and the LHV estimate, and adding the product of the total second fuel flow estimate and the LHV estimate to the first fuel power estimate. In some embodiments, control system 11 may be configured to determine a first power estimate of the second fuel based on the first total indicated engine power and determine a second power estimate of the second fuel based on the LHV estimate and a product of the thermal efficiency parameter and the estimated engine second fuel flow. In various embodiments, the thermal efficiency parameter corresponds to a thermal efficiency correction amount. The control system 11 may then determine a final second fuel power estimate based on the first power estimate and the second power estimate of the second fuel. In various embodiments, the control system 11 may be configured to estimate the G/D of the internal combustion engine 20. In various embodiments, the control system 11 is configured to estimate the G/D of the internal combustion engine 20 by dividing the final second fuel power estimate by the first total engine power estimate.
As shown in fig. 5, in operation 460, the control system 11 may then calculate a difference between the first total indicated engine load (e.g., power, torque, etc.) and the second total indicated engine load (e.g., power, torque, etc.) determined in operation 450. Then, in operation 465, the control system 11 may compare the difference between the first total indicated engine load and the second total indicated engine load (calculated in operation 460) with a predetermined threshold. For example, in various implementations, control system 11 may determine a difference between the predetermined threshold and a difference between the first total indicated engine load and the second total indicated engine load (i.e., a total indicated engine load delta). In various embodiments, the predetermined threshold may be set by the OEM and/or the user of the dual fuel engine system 10.
Thus, if the difference between the total indicated engine load delta and the predetermined threshold is greater than the predetermined amount, the control system 11 may determine that the dual fuel engine system 10 is operating under abnormal or adverse conditions. In various embodiments, the predetermined threshold is associated with a predetermined period of time. In various embodiments, the predetermined threshold may be set, such as by the controller 18. For example, if the difference between the total indicated engine load delta and the predetermined threshold is greater than a predetermined amount within a predetermined period of time, the control system 11 may determine that the dual fuel engine system 10 is operating in an abnormal or unfavorable condition. Accordingly, in response to control system 11 determining that the difference between the first total indicated engine load and the second total indicated engine load meets a predetermined threshold (or the total indicated engine load increases beyond a predetermined amount), control system 11 may activate one or more engine protection measures 470. For example, the control system 11 may disable dual fuel operation, perform a shutdown, and/or reduce engine speed, among other things.
In other embodiments, the control system 11 may be configured to determine one or more second fuel power targets associated with the internal combustion engine 20. FIG. 6 illustrates a method 500 of determining a second fuel power target associated with the internal combustion engine 20. The control system 11 measures engine speed in operation 505 and estimates an amount of engine power in operation 510. In various embodiments, engine speed is sensed by sensors 95, 35, and/or 40. In some embodiments, the engine power amount is a net engine power amount. In operation 515, the control system 11 may calculate a percentage of the rated power ("percent power") of the internal combustion engine 20 based on the estimated engine power from operation 510. The percent rated power may be calculated by dividing the net engine power by the rated engine power limit and multiplying by 100%. The control unit may also determine an intake manifold temperature (e.g., a maximum intake manifold temperature) in operation 525 and an estimate of the KPI of the second fuel in operation 530. The control system 11 may determine a base second fuel substitution rate (G/D) target for the internal combustion engine 20 in operation 520. In various embodiments, the control system 11 determines the base G/D target based on the engine speed, the percent rated power, the intake manifold temperature (determined in operation 525), and the estimated KPI of the internal combustion engine 20. Then, in operation 535, the control system 11 determines a second fuel power target for the internal combustion engine 20 based on the base second fuel substitution target determined in operation 520. In various embodiments, the second fuel power target is based on the base G/D target and the first indicated engine power estimate. In some embodiments, control system 11 determines the first indicated engine power estimate by performing operation 420 of method 400. In various embodiments, the control system 11 is configured to determine (e.g., calculate) the first indicated engine power based on the estimated amount of engine power and the amount of frictional power loss.
In various embodiments, the base G/D target determined in operation 520 is based on a first rotational speed base G/D target (which may be determined in operation 540) when the engine speed is above a threshold and a rotational speed base G/D target (which may be determined in operation 545) when the engine speed is below the threshold. In various embodiments, at least one of the first or second speed base G/D targets is determined based on the intake manifold temperature (determined in operation 525) and/or the estimated KPI (such as the methane value) (determined in operation 530). In various embodiments, the first rotational speed base G/D target is a high speed base G/D target and the second rotational speed base G/D target is a low speed base G/D target (i.e., lower than the first base G/D target). In some embodiments, the high speed base G/D target is based on a percentage rated power, intake manifold temperature, and KPI estimates. Similarly, the low speed base G/D target is based on percent rated power, intake air temperature, and KPI estimates. Thus, the basic G/D target determined in operation 520 is further determined by engine speed-based interpolation between the high-speed basic G/D target and the low-speed basic G/D target. In various embodiments, the high speed basic G/D target is determined from a first set of look-up tables and the low speed basic G/D target is determined from a second set of look-up tables (i.e., from look-up table/database 145).
In various embodiments, the control system 11 may be configured to operate the dual fuel engine system 10 in order to determine one or more second fuel injector commands for at least one engine block within the internal combustion engine 20. Fig. 7 illustrates a method 600 for determining at least one second fuel injector command for at least one engine block within an internal combustion engine 20. In operation 605, the control system 11 is configured to determine a second fuel flow target. In various implementations, the second fuel flow target is based on the second fuel power target determined in operation 625, the thermal efficiency estimate determined in operation 630, and the LHV determined in operation 635. In some implementations, the second fuel power target determined in operation 625 is determined by the control system 11 via the method 500. In other implementations, the LHV determined in operation 635 is determined via the control system 11 performing one or more operations similar or equivalent to operation 445. In other embodiments, the LHV determined in operation 635 is determined via an LHV sensor or a lookup table based on measured or estimated KPIs. In various embodiments, determining the second fuel flow target in operation 605 includes dividing the second fuel power target by the thermal efficiency estimate and the LHV.
The control system 11 is configured to adjust the second fuel flow target in operation 610 based on at least one of the measured second fuel temperature determined in operation 640 and/or the second fuel injector pressure measured in operation 645. In various embodiments, at least one of the second fuel temperature or the second fuel injector pressure is measured by sensors 35, 40, and/or 95. Using the adjusted second fuel flow target determined in operation 610, the control system 11 is configured to determine at least one base second fuel injector command in operation 615. In various embodiments, at least one base second fuel injector command is also determined based on the estimated G/D of the internal combustion engine 20 determined in operation 650 and the G/D target determined in operation 655. In various implementations, the G/D target determined in operation 655 is determined by the control system 11 by implementing one or more operations similar or equivalent to operation 520. Then, in operation 620, the control system 11 may determine at least one second fuel injector command for at least one engine block of the internal combustion engine 20. In some embodiments, the second fuel power target is based on the first indicated engine power estimate and the G/D target. In various implementations, the first indicated engine power estimate is determined by control system 11 by performing operation 420. In some implementations, adjusting the second fuel flow target in operation 610 includes calculating an adjusted second fuel flow target amount. In various embodiments, the second fuel flow target amount is based on a product of the second fuel flow target and at least one of a first ratio of the measured second fuel temperature to a temperature reference or a second ratio of the measured second fuel injector pressure to a pressure reference.
In various implementations, the control system 11 may also be configured to estimate the total second fuel flow. In various embodiments, the estimated total second fuel flow is based on the measured second fuel injector pressure (determined in operation 645), the measured second fuel temperature (determined in operation 640), and at least one second fuel injector command for at least one engine group. In some implementations, the at least one second fuel injector command for the at least one engine group includes a left group second fuel injector command (i.e., for left group 30) and a right group second fuel injector command (i.e., for right group 31). In other implementations, determining the left set of second fuel injector commands and determining the right set of second fuel injector commands includes biasing at least one second fuel injector command for at least one engine block to each of the left set 30 and the right set 31. In various embodiments, biasing the at least one second fuel injector command for the at least one engine group to each of the left and right groups 30, 31 is based on an exhaust temperature differential associated with each of the left and right groups 30, 31. In some embodiments, the exhaust gas temperature differential is measured by sensors 35, 40, and/or 95. In other embodiments, the exhaust temperature difference corresponds to the difference between the exhaust temperature measured at the left bank 30 and the exhaust temperature measured at the right bank 31. Thus, during operation of dual engine system 10, control system 11 may measure the exhaust temperature of left bank 30, measure the exhaust temperature of right bank 31, and determine the difference between the exhaust temperature of left bank 30 and the exhaust temperature of right bank 31. Control system 11 may then add the left set of adjustments to at least one second fuel injector command for at least one engine block. In various embodiments, control system 11 adds the left set of adjustment amounts to at least one second fuel injector command to determine a first adjusted base second fuel injector command based on a difference between the left set of exhaust temperatures and the right set of exhaust temperatures. Similarly, control system 11 may then add the right set of adjustment amounts to at least one second fuel injector command for at least one engine block. In various embodiments, control system 11 adds the right set of adjustment amounts to at least one injector command for the second fuel to determine a second adjusted base second fuel injector command based on a difference between the left set of exhaust temperatures and the right set of exhaust temperatures. Control system 11 may then convert each of the first adjusted base second fuel injector command and the second adjusted base second fuel injector command to a left set of second fuel injector commands and a right set of second fuel injector commands, respectively.
In some implementations, determining at least one second fuel injector command for at least one engine block in operation 615 includes determining a feed-forward input for a G/D PID controller operatively coupled to the internal combustion engine 20. In various embodiments, the G/D PID controller is the controller 150. In some embodiments, the feed forward input is based on a look-up table. In various embodiments, a lookup table is determined or referenced from the first fuel ECM and torque fueling calculation module 45, the first fuel air handling, aftertreatment, and fuel system reference determination and control module 60, and/or the indicated engine power and the second fuel power estimation module 115. In various embodiments, the lookup table is based on at least one of a measured second fuel injector pressure, a measured second fuel temperature, or an adjusted second fuel flow target amount. In some embodiments, the control system 11 is further configured to determine at least one thermal control valve command. In various embodiments, at least one thermal control valve command is associated with the heater control valve 195. In some embodiments, the at least one thermal control valve command is based on a measured second fuel temperature and/or a measured second fuel mass flow within the internal combustion engine 20. In still other embodiments, the control system 11 is further configured to adjust the at least one second fuel temperature setpoint based on the measured KPIs and/or the estimated KPI number. In various embodiments, the measured KPIs are measured by sensors 35, 40, and/or 95. In some embodiments, the estimated KPI number is determined by KPI estimation module 125. In some implementations, the at least one second fuel temperature set point is based on an engine protection set point. In various embodiments, the engine protection set point is determined or set by the OEM system 12, the first fuel control system 14, or the second fuel control system 16.
Fig. 8 illustrates a method 700 performed by the dual fuel engine system 10. In various embodiments, the dual fuel engine system 10 includes at least one PID controller coupled to the internal combustion engine 20 and the second fuel injector 28. In operation 705, the control system 11 determines a G/D estimation. In various embodiments, the G/D estimate is determined from LHV and G/D estimation module 120. The control system 11 then determines the G/D target in operation 710. In various embodiments, control system 11 determines the G/D target in operation 710 by performing one or more operations similar or equivalent to operation 520 in method 500. In operation 715, at least one PID controller is configured to receive a feed-forward input in addition to the G/D estimate and the G/D target. In various embodiments, the feed forward input is based on a lookup table that may be determined or referenced from the first fuel ECM and torque fueling calculation module 45, the first fuel air treatment, aftertreatment, and fuel system reference determination and control module 60, and/or the indicated engine power and the second fuel power estimation module 115. In some embodiments, the G/D target is determined from the LHV and G/D estimation module 120. In operation 720, the at least one PID controller is configured to output at least one second fuel injector command. In operation 725, the at least one PID controller then biases the at least one second fuel injector command to each of the left and right banks 30, 31. In various embodiments, the at least one PID controller biases the at least one second fuel injector command to each of the left and right banks 30, 31 based on the difference between each of the left and right banks of exhaust temperatures (determined in operation 730). In various embodiments, an exhaust temperature difference is determined in operation 740. In some embodiments, the at least one PID controller comprises a first PID controller and a second PID controller. For example, a first PID controller may be configured to receive feed forward input, G/D estimates, and G/D targets (i.e., PID controller 150), and a second PID controller may be configured to bias at least one second fuel injector command to each of the left and right banks 30, 31 (i.e., bank balance PID 155).
In some embodiments, the dual fuel engine system 10 includes an aftertreatment system operably coupled to the internal combustion engine 20 (i.e., controlled by the aftertreatment control system 85), a second fuel injection system including at least one second fuel injector 28 (i.e., controlled by the second fuel injector control module 110), and an air handling system operably coupled to the internal combustion engine 20 (i.e., controlled by the air handling control system 80). In some implementations, the aftertreatment system is a Selective Catalytic Reduction (SCR) and Oxidation Catalyst (OC) system. In some embodiments, the second fuel injection system is configured to independently control the second fuel injection (i.e., via at least one second fuel injector 28) on each of the left and right groups 30, 31. In other embodiments, the air handling system is configured to control air flow through the internal combustion engine 20. In some embodiments, the air handling system controls air flow independent of operating conditions of the internal combustion engine 20. In other embodiments, the air flow is based on predetermined values obtained from a look-up table. In various embodiments, the lookup table is determined by database 75 in module 60 or corresponds to database 75. In various embodiments, the predetermined value is associated with a target temperature in at least one location of the aftertreatment system.
In various embodiments, the dual fuel engine system 10 includes one or more heaters operatively coupled to at least one second fuel injector 28 and the internal combustion engine 20. The at least one heater is configured to adjust the temperature (i.e., heat) of the second fuel flowing within the internal combustion engine 20. Fig. 9 illustrates a method 800 for controlling an operating state of a heater coupled to an internal combustion engine 20. In operation 805, the control system 11 is configured to determine a second fuel flow target. For example, control system 11 is configured to determine the second fuel flow target via one or more operations similar to or equivalent to operation 605. In various implementations, the second fuel flow target determined in operation 805 may be based on one or more of a second fuel power target, an estimated thermal efficiency, and an LHV. For example, the second fuel flow target may be based on the second fuel power target determined in operation 820, the estimated thermal efficiency of the internal combustion engine 20 determined in operation 825, and the LHV determined in operation 830. In operation 810, the control system 11 may adjust the second fuel flow target based on at least one of the measured second fuel temperature or the measured second fuel injector pressure. For example, in operation 810, the control system 11 is configured to adjust the second fuel flow target based on at least one of the measured second fuel temperature determined in operation 835 or the measured second fuel injector pressure determined in operation 840. In various implementations, the measured second fuel temperature determined in operation 835 is determined by control system 11 by performing one or more operations similar to or equivalent to operation 640. In some embodiments, the measured second fuel temperature is determined via sensors 35, 40, and/or 95. In various embodiments, the measured second fuel injector pressure determined in operation 840 is determined by control system 11 by performing one or more operations similar to or equivalent to operation 645. In some embodiments, the measured second fuel injector pressure is determined via sensors 35, 40, and/or 95. The control system 11 may then control the operating state of the heater 32 based on at least one of the measured second fuel temperature or the measured engine coolant temperature. In some embodiments, at least one of the measured second fuel temperature or the measured engine coolant temperature is determined via sensors 35, 40, and/or 95.
In some embodiments, the control system 11 is configured to perform on/off control of the heater 32 in response to a determination made regarding the measured second fuel temperature relative to one or more threshold temperatures. For example, the control system 11 is configured to control operation of the heater 32 in response to determining that the measured second fuel temperature is less than the first threshold temperature for the first period of time. Specifically, in some embodiments, control system 11 is configured to operate (i.e., turn on) heater 32 in response to determining that the measured second fuel temperature (determined in operation 835) is less than the first threshold temperature for the first period of time. In various embodiments, the first threshold temperature is set by the OEM system 12, the first fuel control system 14, or the second fuel control system 16. In other embodiments, the control system 11 is configured to control operation of the heater 32 in response to determining that the measured second fuel temperature is greater than the second threshold temperature for a second period of time. For example, the control system 11 is configured to operate (i.e., turn off) the heater 32 in response to determining that the measured second fuel temperature (determined in operation 835) is greater than the second threshold temperature for the second period of time. In various embodiments, the second threshold temperature is set by the OEM system 12, the first fuel control system 14, or the second fuel control system 16.
Although embodiments are described above with reference to fig. 1-9, various modifications and adaptations of those embodiments are contemplated as within the scope of the present disclosure.
The present technology may also include, but is not limited to, the features and combinations of features recited in the following alphabetical paragraphs, it should be understood that the following paragraphs should not be construed as limiting the scope of the appended claims or requiring that all such features be included in such claims:
A. a method for controlling a dual fuel engine system, the method comprising:
Estimating a total indicated engine load based on a sum of the measured engine power and the power loss estimate, and
Determining a total fuelling amount based on the engine speed and the total indicated engine load, the total fuelling amount comprising a fuelling amount of a first fuel and a fuelling amount of a second fuel, and
The total fuelling amount is used to control the dual fuel engine system.
B. The method of paragraph a, wherein the method further comprises determining a first updated total fueling amount based on a maximum between the total fueling amount and a first fuel command for the first fuel.
C. The method of paragraph B, wherein the method further comprises determining a second updated total fueling amount, and wherein determining the second updated total fueling amount comprises subtracting the first fuel command for the first fuel from the first updated total fueling amount to determine a first fuel equivalent for a second fueling amount, and adding the first fuel equivalent for a second fueling amount to a second fuel command for the first fuel.
D. the method of paragraph a, wherein controlling the dual fuel engine system includes determining a first fuel system actuator command.
E. The method of paragraph a, wherein determining the total fuelling amount includes referencing a torque-to-fuel look-up table based on the engine speed and an indication of a first fuel torque input.
F. The method of paragraph a, wherein the method further comprises determining the power loss estimate based on a friction torque estimate, an accessory torque estimate, a charge air pumping torque, and the engine speed.
G. The method of paragraph F, wherein the method further comprises:
Determining the friction torque estimate from a second lookup table, the second lookup table based on the engine speed and an engine friction parameter;
Wherein the engine friction parameter is based on at least one of an oil temperature or a coolant temperature within the dual fuel engine system.
H. the method of paragraph E, wherein the method further comprises determining the accessory torque estimate from a third lookup table, the third lookup table being based on the engine speed and accessory torque parameters.
I. The method of paragraph H, wherein the method further comprises determining the accessory torque parameter based on a cooling fan power or duty cycle commanded by the dual fuel engine system.
J. The method of paragraph B, wherein the method further comprises determining at least one actuator command based on the engine speed and at least one of the first updated total fueling amount or the second updated total fueling amount.
K. the method of paragraph a, wherein the method further comprises determining the first fuel command for the first fuel from a torque-to-fuel look-up table based on a sum of a friction power estimate and a torque demand, the torque demand being set by an engine governor within the dual fuel engine system, and the engine speed.
A method for controlling a dual fuel engine system, the method comprising:
estimating a total indicated engine load, the total indicated engine load based on a sum of the measured engine power, the friction power estimate, and the accessory power estimate;
determining a total fuelling amount from a first look-up table, the look-up table being based on an engine speed and the total indicated engine load;
determining at least one updated total fueling based on the total fueling and an operating state of a dual fuel mode switch within the dual fuel engine system, and
Determining a control input of at least one actuator within the dual fuel engine system;
Wherein the control input is based on selecting a corresponding set of look-up tables associated with the at least one actuator, the set of look-up tables comprising a plurality of look-up tables, each of the plurality of look-up tables being based on the engine speed and the at least one updated total fueling amount.
The method of paragraph L, wherein the at least one actuator is at least one of an air handling actuator, an aftertreatment actuator, or a first fuel system actuator.
The method of paragraph L, wherein selecting the corresponding set of look-up tables includes determining a compressor inlet density, a second fuel substitution rate within the dual engine system, and the operating state of the dual fuel mode switch.
The method of paragraph N, wherein selecting the set of look-up tables further comprises selecting at least one of an air handling reference table, a post-handling reference table, or a fueling reference table.
The method of paragraph O, wherein the at least one updated fueling quantity comprises a first updated fueling quantity and a second updated fueling quantity, wherein the first updated fueling quantity corresponds to a maximum between the total fueling quantity and a fueling command for a first fuel, and wherein the second updated fueling quantity is determined by subtracting the fueling command for the first fuel from the first updated total fueling quantity to determine a first fueling equivalent of a fueling quantity of a second fuel, and adding the fueling quantity of the first fueling equivalent to the fueling command for the first fuel.
Q. a dual fuel engine system comprising:
An internal combustion engine operable in a dual fuel mode;
At least one actuator operatively coupled to the internal combustion engine, and
At least one controller in communication with the internal combustion engine and the at least one actuator;
wherein the at least one controller is configured to:
receiving a first input corresponding to an engine speed and a second input corresponding to a measured engine power;
calculating a power loss estimated value;
Determining a total fuelling amount based on the measured engine power and power loss estimates;
Determining a first fuel command for a first fuel associated with the internal combustion engine based at least on the calculated governor command and the power loss estimate;
determining at least one updated total fueling based on the total fueling and the first fuel command for the first fuel;
Selecting a set of look-up tables associated with the at least one actuator based on a second fuel substitution rate associated with the internal combustion engine, the set of look-up tables based on the engine speed and the at least one updated total fueling amount, and
An input is sent to the at least one actuator based on the set of look-up tables.
The system of paragraph Q, wherein the at least one controller is further configured to determine an indication of a first fuel torque input based on a sum of the friction power estimate and an engine speed torque demand, the engine speed torque demand corresponding to a difference between the engine speed and an engine speed target.
S. the system of paragraph Q, wherein the at least one controller is configured to determine the power loss estimate based on a friction torque estimate, an accessory torque estimate, a charge air pumping torque, and the engine speed.
T. the system of paragraph Q, wherein the at least one controller is further configured to select the lookup table based on a compressor inlet density.
U. a method for controlling a dual fuel engine system configured to operate with a first fuel and a second fuel, the method comprising:
determining an amount of friction power loss for an internal combustion engine of the dual fuel engine system, the amount of friction power loss based on an engine speed and a friction torque estimate for the internal combustion engine;
Determining an accessory power loss amount of power of the internal combustion engine, the accessory power loss amount based on the engine speed and an accessory torque estimate;
Estimating a net engine power amount based on the accessory power loss amount and a brake power amount of the internal combustion engine;
estimating an indicated power of the first fuel, and
A first indicated engine power and a first power of the second fuel are estimated based on the estimated net engine power.
V. the method of paragraph U, wherein estimating the indicated power of the first fuel comprises multiplying the determined thermal efficiency correction amount by a determined power estimate of the first fuel.
W. the method of paragraph V, wherein determining the power estimate of the first fuel comprises using a first lookup table that is based on a fuel rate of the first fuel and the engine speed.
X. the method of paragraph V, wherein determining the thermal efficiency correction amount includes consulting a first set of look-up tables based on at least one of a substitution rate of the second fuel, a knock tendency index, or an intake manifold temperature.
The method of paragraph V, further comprising determining a Lower Heating Value (LHV) estimate of the second fuel based on the first power of the second fuel, a total second fuel flow estimate, and the thermal efficiency correction amount.
The method of paragraph Y, wherein determining the LHV estimate comprises:
dividing the first power of the second fuel by a product of the second fuel flow estimate and the thermal efficiency correction to determine an instantaneous LHV amount.
The method of paragraph Z, further comprising applying a learning algorithm to the instantaneous LHV quantity to determine the LHV estimate.
BB. the method of paragraph Y, further comprising estimating a second total indicated engine power, wherein estimating the second total indicated engine power comprises:
Determining a product of the total flow estimate of the second fuel and the LHV estimate, and
A sum of the product of the total second fuel flow and the LHV estimate and the power estimate of the first fuel is determined.
The method of paragraph BB, further comprising determining a difference between the first total indicated engine power and the second total indicated engine power.
DD. the method of paragraph CC, further comprising activating at least one engine protection measure based on a difference between the first total indicated engine power and the second total indicated engine power being greater than a threshold.
A method according to paragraph DD, further comprising setting the threshold to correspond to a predetermined period of time.
FF. the method of paragraph V, wherein estimating the first power of the second fuel includes subtracting the indicated power of the first fuel from the indicated engine power.
A method for controlling a dual fuel engine system configured to operate using a first fuel and a second fuel, the method comprising:
estimating a net engine power amount of an internal combustion engine of the dual fuel engine system based on an accessory power loss amount of power of the internal combustion engine and a brake power estimate of the internal combustion engine;
determining a first total indicated engine power based on the net engine power and a frictional power loss amount of the internal combustion engine;
determining a Lower Heating Value (LHV) for the second fuel within the internal combustion engine, the LHV being a measured or estimated value;
estimating a second total indicated engine power based on the LHV, the total flow estimate of the second fuel, and the power estimate of the first fuel, and
At least one engine protection measure is activated based on a difference between the first total indicated engine power and the second total indicated engine power being greater than a predetermined threshold.
HH. the method of paragraph GG, wherein estimating the second total indicated engine power comprises:
a sum of a product of a total second fuel flow and the LHV and the power estimate of the first fuel is determined.
The method of paragraph GG, further comprising:
Determining a first power estimate for the second fuel, the first power estimate for the second fuel based on the first total indicated engine power;
Determining a second power estimate of said second fuel, said second power estimate of said second fuel being based on a product of a thermal efficiency estimate and a total second fuel flow estimate and said LHV, and
A final second fuel power estimate is determined based on the first power estimate of the second fuel and the second power estimate of the second fuel.
The method of paragraph II, further comprising estimating a substitution rate of the second fuel, wherein estimating the substitution rate of the second fuel comprises:
dividing the final second fuel power estimate by the first power estimate.
KK. a dual fuel engine system operable in a dual fuel mode, the dual fuel engine system comprising:
at least one controller in communication with an internal combustion engine configured to operate using a first fuel and a second fuel;
wherein the at least one controller is configured to:
receiving an input corresponding to an engine speed of the internal combustion engine;
receiving an input for calculating a net engine power estimate;
calculating a percent rated power of the internal combustion engine based on the engine speed and the net engine power estimate;
Determining a base substitution target for the second fuel of the internal combustion engine based on the engine speed, the percent rated power, an intake manifold temperature within the internal combustion engine, and a knock tendency index estimation within the internal combustion engine, and
A second fuel power target for the internal combustion engine is determined based on the base substitution target for the second fuel and a first indicated engine power estimate.
LL. the system of paragraph KK, wherein the controller is configured to determine the base substitution target for the second fuel by:
Determining a first rotational speed base substitution target for the second fuel based on the percent rated power, the intake manifold temperature, and the knock tendency index estimate when the engine speed is above a threshold;
Determining a second speed base substitution target for the second fuel based on the percent rated power, the intake manifold temperature, and the knock tendency index estimate when the engine speed is below the threshold value, and
The basic substitution target of the second fuel is determined based on the engine speed, the high-speed basic substitution target of the second fuel, and the low-speed basic substitution target of the second fuel.
MM. the system of paragraph LL, wherein the first speed base substitution target for the second fuel is determined based on a first set of look-up tables, and the second speed base substitution target for the second fuel is determined based on a second set of look-up tables.
NN. the system of paragraph KK, wherein the controller is configured to determine the first indicated engine power based on the net engine power estimate and a frictional power loss amount.
OO. a method for controlling a dual fuel engine system configured to operate with a first fuel and a second fuel, the method comprising:
Determining a flow target of the second fuel for an internal combustion engine of the dual fuel engine system, the flow target of the second fuel being based on a power target of the second fuel of the internal combustion engine, a thermal efficiency estimate of the internal combustion engine, and a Lower Heating Value (LHV) within the internal combustion engine;
adjusting the flow target of the second fuel based on at least one of a measured second fuel temperature or a measured second fuel injector pressure;
determining at least one base second fuel injector command based on the adjusted flow target, the second fuel substitution estimate, and the second fuel substitution target of the second fuel, and
A second fuel injector command for at least one engine group is determined based on the at least one base second fuel injector command.
PP. the method of paragraph OO, further comprising estimating a total second fuel flow based on the measured second fuel injector pressure, the measured second fuel temperature, and the at least one injector command for the second fuel of the at least one engine unit.
QQ. the method of paragraph OO, wherein the at least one engine block includes a left group and a right group, wherein the at least one injector command for the second fuel of the at least one engine block includes a left group second fuel injector command and a right group second fuel injector command, and determining the left group second fuel injector command and the right group second fuel injector command includes:
The at least one injector command for the second fuel of the at least one engine group is biased to each of the right and left engine groups based on exhaust gas temperature differences associated with each of the right and left engine groups.
RR. the method of paragraph QQ, wherein biasing the at least one base second fuel injector command to each of the right and left engine groups comprises:
Measuring the left set of exhaust temperatures;
measuring the right set of exhaust temperatures;
Determining a difference between the right set of exhaust temperatures and the left set of exhaust temperatures;
Adding a left set of adjustment amounts to the at least one injector command for the second fuel of the at least one engine block to determine a first adjusted base second fuel injector command based on a difference between the right set of exhaust temperatures and the left set of exhaust temperatures;
Adding a right set of adjustment amounts to the at least one injector command for the second fuel of the at least one engine block to determine a second adjusted base second fuel injector command based on a difference between the right set of exhaust temperatures and the left set of exhaust temperatures, and
Each of the first adjusted basic second fuel injector command and the second adjusted basic second fuel injector command is converted to the left set of second fuel injector commands and the right set of second fuel injector commands, respectively.
SS. the method of paragraph OO, wherein determining the flow target of the second fuel includes dividing the power target of the second fuel by the thermal efficiency estimate and the LHV.
TT. the method of paragraph SS, wherein the power target of the second fuel is based on a first indicated engine power estimate and the second fuel substitution target.
A method according to paragraph OO, wherein adjusting the flow target of the second fuel comprises:
An adjusted second fuel flow target amount is calculated, the adjusted second fuel flow target amount being a product of the flow target and at least one of a first ratio of the measured second fuel temperature to a temperature reference or a second ratio of the measured pressure to a pressure reference.
Vv. the method of paragraph UU, wherein determining at least one injector command for the second fuel of the at least one engine block comprises:
A feed-forward input for a second fuel-alternative proportional-integral-derivative controller operatively coupled to the internal combustion engine is determined, the feed-forward input being based on a look-up table referencing at least one of the measured second fuel injector pressure, the measured second fuel temperature, or the adjusted second fuel flow target amount.
WW. the method of paragraph VV, further comprising:
At least one temperature set point of the second fuel is adjusted based on at least one of the measured knock tendency index or the estimated knock tendency index.
XX. the method of paragraph WW, wherein the at least one temperature set point of the second fuel is based on an engine protection set point.
YY. a dual fuel engine system for an internal combustion engine, the dual fuel engine system configured to operate with a first fuel and a second fuel, the dual fuel engine system comprising:
at least one injector for the second fuel, the at least one injector being operably coupled to the internal combustion engine, the internal combustion engine having a left group and a right group, the internal combustion engine being operable in a dual fuel mode, and
At least one proportional-integral-derivative (PID) controller communicatively coupled to the internal combustion engine and the at least one injector for the second fuel;
wherein the at least one PID controller is configured to:
Receiving a feed forward input, a second fuel substitution estimate, and a second fuel substitution target;
Outputting at least one injector command for the second fuel based on the feed-forward input, and
The at least one injector command for the second fuel is biased to each of the right and left groups based on exhaust temperature differences associated with each of the right and left groups.
ZZ. the system of paragraph YY, wherein the at least one PID controller is configured to bias the at least one injector command for the second fuel to each of the right and left groups by performing operations comprising:
Measuring the left set of exhaust temperatures;
measuring the right set of exhaust temperatures;
Determining a difference between the right set of exhaust temperatures and the left set of exhaust temperatures;
Adding a left set of adjustment amounts to the at least one injector command for the second fuel to determine a first adjusted injector command for the second fuel;
Adding a right set of adjustment amounts to the at least one injector command for the second fuel to determine a second adjusted injector command for the second fuel, and
Each of the first adjusted injector commands for the second fuel and the second adjusted injector commands for the second fuel are converted to a left set of injector commands for the second fuel and a right set of injector commands for the second fuel, respectively.
The system of paragraph YY, wherein the at least one PID controller comprises a first PID controller and a second PID controller, wherein the first PID controller is configured to receive the feed forward input, the second fuel substitution estimate, and the second fuel substitution target, and wherein the second PID controller is configured to bias the at least one injector command for the second fuel to each of the right and left banks.
The system of paragraph YY, further comprising:
an aftertreatment system operably coupled to the internal combustion engine, the aftertreatment system being a Selective Catalytic Reduction (SCR) and Oxidation Catalyst (OC) system;
An injection system for the second fuel operably coupled to the internal combustion engine, the injection system for the second fuel comprising the at least one injector for the second fuel, wherein the injection system for the second fuel is configured to independently control injection of the second fuel on each of the left and right groups, and
An air handling system operatively coupled to the internal combustion engine, the air handling system configured to control an air flow through the internal combustion engine independent of an operating condition of the internal combustion engine, wherein the air flow is based on predetermined values obtained from a lookup table, the predetermined values being associated with a target temperature in at least one location of the aftertreatment system.
Ccc. a dual fuel engine system operable in a dual fuel mode, the dual fuel engine system comprising:
an internal combustion engine having at least one engine block, the internal combustion engine configured to operate using a first fuel and a second fuel;
at least one injector for the second fuel, the at least one injector operatively coupled to the internal combustion engine, and
At least one controller communicatively coupled to the internal combustion engine and the at least one injector for the second fuel;
wherein the at least one controller is configured to:
Determining a second fuel flow target for the internal combustion engine, the second fuel flow target based on a second fuel power target of the internal combustion engine, a thermal efficiency estimate of the internal combustion engine, and a Lower Heating Value (LHV) within the internal combustion engine;
adjusting the second fuel flow target based on at least one of the measured second fuel temperature or the measured second fuel injector pressure to determine an adjusted second fuel flow target for the dual fuel mode;
Determining at least one base second fuel injector command based on the adjusted second fuel flow target, the second fuel substitution estimate, and the second fuel substitution target, and
An injector command for the second fuel of the at least one engine block is determined based on the at least one base second fuel injector command.
A system according to paragraph CCC, wherein the at least one controller is further configured to:
a left set of second fuel injector commands and a right set of second fuel injector commands are determined based on the at least one injector command for the second fuel.
The system of paragraph DDD, wherein the at least one controller is further configured to determine the second fuel flow target by dividing the second fuel power target by a thermal efficiency estimate and a Lower Heating Value (LHV), wherein the LHV is determined on a lookup table based on the estimated knock tendency index.
It should be noted that the term "exemplary" and variations thereof as used herein to describe various embodiments are intended to indicate that the embodiments are possible examples, representations, or illustrations of possible embodiments (and the term is not intended to imply that the embodiments are necessarily the particular or highest level examples).
As used herein, the term "coupled" and variants thereof refer to two components being directly or indirectly coupled to one another. Such coupling may be stationary (e.g., permanent or fixed) or movable (e.g., removable or releasable). Such coupling may be accomplished with two members directly coupled to each other, wherein the two members are coupled to each other using a separate intermediate member and any additional intermediate members coupled to each other, or wherein the two members are coupled to each other using an intermediate member that is integrally formed as a single unitary body with one of the two members. If "coupled" or variations thereof is modified by additional terminology (e.g., directly coupled), the generic definition of "coupled" provided above is modified by the plain language meaning of the additional terminology (e.g., "directly coupled" meaning that two members are coupled without any separate intermediate member), resulting in a narrower definition than the generic definition of "coupled" provided above. This coupling may be mechanical, electrical or fluid.
References herein to the location of elements (e.g., "top," "bottom," "above," "below") are used merely to describe the orientation of the various elements in the drawings. It should be noted that the orientation of the various elements may be different according to other exemplary embodiments, and such variations are intended to be included in the present disclosure.
In some embodiments, the hardware and data processing components used to implement the various processes, operations, illustrative logic, logic blocks, modules, and circuits described in connection with the embodiments disclosed herein, such as the hardware and data processing components of a controller (e.g., memory within the controller 18, memory within the OEM system 12, memory within the first fuel control system 14, or memory within the second fuel control system 16), may be implemented or performed with a general purpose single or multi-chip processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some embodiments, particular processes and methods may be performed by circuitry specific to a given function. The memory (e.g., memory unit, storage device) may include one or more devices (e.g., RAM, ROM, flash memory, hard disk storage) for storing data and/or computer code to complete or facilitate the various processes, layers, and modules described in this disclosure. The memory may be or include volatile memory or non-volatile memory and may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described in this disclosure. According to an exemplary embodiment, the memory (e.g., memory within the controller 18, memory within the OEM system 12, memory within the first fuel control system 14, or memory within the second fuel control system 16) is communicatively connected to the processor via the processing circuitry and includes computer code for performing (e.g., by the processing circuitry or the processor) one or more processes described herein.
The present disclosure contemplates methods and systems for implementing various operations (e.g., such as operations 305-360 of method 300, operations 405-470 of method 400, operations 505-545 of method 500, operations 605-655 of method 600, operations 705-740 of method 700, and operations 805-845 of method 800) on any machine-readable medium. Embodiments of the present disclosure may be implemented using an existing computer processor, or by a special purpose computer processor of an appropriate system introduced for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of machine-executable instructions or data structures and that can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions comprise, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machine to perform a certain function or group of functions.
Although the figures and description may show a particular order of method steps, the order of the steps may differ from what is depicted and described, unless otherwise indicated above. Furthermore, two or more steps may be performed concurrently or with partial concurrence, unless stated differently above.
It is important to note that any element disclosed in one embodiment may be combined with or used with any other embodiment disclosed herein. Although only one example from one embodiment has been described above in which elements in another embodiment may be combined or utilized, it should be understood that other elements of the various embodiments may be combined or utilized with any of the other embodiments disclosed herein.