Disclosure of Invention
The embodiment of the application provides an exhaust gas recirculation system, a control method and a vehicle, which solve the problem that the low-rotation-speed working condition and the high-rotation-speed working condition of an engine cannot be considered in the prior art, improve the performance of the engine and reduce the matching difficulty of a turbocharger.
The embodiment of the application provides an exhaust gas recirculation system, which comprises an engine, a turbocharger, an electric turbocharger, an air filter and an electronic control unit (Electronic Control Unit, ECU for short), wherein:
The engine comprises an air inlet main pipe and an exhaust main pipe;
The turbocharger comprises a turbine and a compressor, the compressor is provided with an exhaust port and an air inlet, and the turbine is provided with the exhaust port and the air inlet;
An air inlet of the turbine of the turbocharger is connected with an exhaust manifold of the engine, and an air outlet of the turbine of the turbocharger is connected with an air inlet of the electric turbocharger;
an exhaust port of the electric turbocharger is connected with an air inlet manifold of the engine;
An air inlet of a compressor of the turbocharger is connected with an air filter, and an air outlet of the compressor of the turbocharger is connected with an air inlet manifold of the engine;
The ECU is connected to the engine and the electric turbocharger, and controls the engine and the electric turbocharger.
According to the EGR system provided by the embodiment of the application, the electric turbocharger is added, the exhaust gas is obtained from the exhaust port of the turbine through the electric turbocharger, and then the exhaust gas is transmitted to the air inlet main pipe of the engine, so that the turbocharger only needs to consider the requirement of the engine performance when matching, the problem of taking the EGR gas is not required, the performance of the engine can be improved to the greatest extent, and the method for taking the gas through the electric turbocharger 7 is simple in control strategy and easy to realize.
As an alternative embodiment, the exhaust gas recirculation system further comprises an exhaust gas recirculation mixer, wherein the exhaust gas recirculation mixer comprises a first air inlet, a second air inlet and an air outlet;
An exhaust port of a compressor of the turbocharger is connected with a first air inlet of the exhaust gas recirculation mixer;
An exhaust port of the electric turbocharger is connected with a second air inlet of the exhaust gas recirculation mixer;
The exhaust port of the exhaust gas recirculation mixer is connected to the intake manifold of the engine.
As an alternative embodiment, the exhaust gas recirculation system further comprises an intake heating grid;
the exhaust port of the exhaust gas recirculation mixer is connected to the intake manifold of the engine via an intake heating grid.
As an alternative embodiment, the exhaust gas recirculation system further comprises an exhaust gas recirculation cooler;
the exhaust port of the electric turbocharger is connected to the second intake port of the exhaust gas recirculation mixer through an exhaust gas recirculation cooler.
As an alternative embodiment, the exhaust gas recirculation system further comprises an intercooler;
An exhaust port of a compressor of the turbocharger is connected to a first intake port of the exhaust gas recirculation mixer through an intercooler.
As an alternative embodiment, the exhaust gas recirculation system further comprises a throttle valve;
a throttle valve is also connected between the intercooler and the first air inlet of the exhaust gas recirculation mixer.
As an alternative embodiment, the exhaust gas recirculation system further comprises a plurality of detection devices;
The ECU is also connected with the plurality of detection devices and used for acquiring state parameters measured by the plurality of detection devices and controlling the exhaust gas recirculation system according to the state parameters;
The plurality of detection devices includes:
the vortex front pressure sensor is arranged on an exhaust manifold of the engine and is used for measuring the gas pressure in the exhaust manifold of the engine;
The air inlet temperature and pressure sensor is arranged on an air inlet manifold of the engine and is used for measuring the gas temperature and the gas pressure in the air inlet manifold of the engine;
the rotating speed sensor is arranged on the electric turbocharger and is used for measuring the rotating speed of the electric turbocharger;
A venturi flow meter mounted between the electric turbocharger and the exhaust gas recirculation mixer for measuring the gas flow at the exhaust port of the electric turbocharger;
The differential pressure sensors are arranged on two sides of the venturi flowmeter and are used for measuring differential pressure on two sides of the venturi flowmeter;
And a temperature sensor installed between the EGR cooler and the EGR mixer for measuring the temperature of the gas discharged from the EGR cooler.
The embodiment of the application also provides a control method of the exhaust gas recirculation system, which is applied to the ECU of the waste recirculation system, and comprises the following steps:
acquiring state parameters measured by a plurality of detection devices in an exhaust gas recirculation system;
the exhaust gas recirculation system is controlled in dependence on the state parameter.
As an alternative embodiment, acquiring status parameters measured by a plurality of detection devices in an exhaust gas recirculation system includes:
acquiring real-time gas flow of an exhaust port of an electric turbocharger in an exhaust gas recirculation system measured by a venturi flowmeter and real-time rotating speed of the electric turbocharger measured by a rotating speed sensor;
controlling the exhaust gas recirculation system according to the state parameter, comprising:
the real-time gas flow is differenced with the preset gas flow, and the set rotating speed of the electric turbocharger is calculated by utilizing PID (proportion (P), integral (I) and derivative (D)) based on the difference value of the real-time gas flow and the preset gas flow;
the real-time rotating speed is differenced from the obtained set rotating speed, and the motor duty ratio of the electric turbocharger is calculated by utilizing PID based on the difference between the real-time rotating speed and the set rotating speed;
the electric turbocharger is controlled in accordance with the motor duty cycle.
The embodiment of the application also provides a vehicle comprising the exhaust gas recirculation system.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be described in further detail below with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.
It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.
In addition, if there is a description of "first", "second", etc. in the embodiments of the present application, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present application.
The EGR system is a technology applied to a vehicle for re-introducing exhaust gas discharged from an engine into an intake pipe and mixing fresh gas and then entering a combustion chamber for combustion, which can effectively reduce the emission of nitrogen oxides from the engine and can improve fuel economy at the time of partial load. The introduction of an EGR system in a vehicle can reduce the combustion temperature and pressure by absorbing part of the heat generated by combustion, and can effectively improve the thermal efficiency of the engine.
With the rise of the emission requirements of an engine, an EGR system is generally adopted in a vehicle to reduce the content of nitrogen oxides in exhaust gas of the vehicle, but in order to meet the EGR exhaust gas requirements of the engine in the EGR system, the performance requirements of the engine and the EGR exhaust gas quantity of an engine emission area are generally required to be considered when matching a turbocharger, so that the turbocharger cannot meet the performance requirements of all areas where the engine operates, and the high-speed performance is relatively poor, the exhaust temperature is increased and the altitude capability is poor.
Fig. 1 is a block diagram of an EGR system in the prior art according to an embodiment of the present application, as shown in fig. 1, in an EGR system that is currently commonly used, an EGR valve is usually disposed behind an exhaust manifold of an engine, and the other side of the EGR valve is connected to an intake manifold of the engine through an intercooler, etc., and when the air pressure (i.e., a pre-vortex pressure value) of the exhaust manifold of the engine is greater than the pressure of the intake manifold of the engine, the EGR valve is opened to allow a part of exhaust gas discharged from the engine to enter the intake manifold of the engine through the EGR valve, so as to enter an internal cylinder to perform combustion, i.e., obtain exhaust gas through a pressure difference between exhaust gas and intake gas of the engine.
However, when the engine is in a low rotation speed region, the EGR valve cannot be opened due to the low turbopressure value, so that the exhaust gas cannot be obtained at this time, and the emission requirement of the region is affected. Meanwhile, in the case of turbocharger configuration, the turbine of the turbocharger is usually matched relatively small for cooperation with the EGR valve, and thus performance in a high-speed region of the engine is affected, so that power performance, economy, and the like of the engine are affected in the entire operation condition.
In order to solve the above problems and simultaneously consider the performance requirement of the engine and the exhaust emission requirement of the engine, the embodiment of the application provides an EGR system and a control method of the EGR system, which effectively improves the EGR rate of the EGR system by removing an EGR valve in the EGR system, adding an electric turbocharger (a turbine driven by a motor to do work) after a turbine of the turbocharger, and obtaining exhaust gas from an exhaust port of the turbine of the turbocharger through the operation of the electric turbocharger.
Although the electric turbocharger is added in the embodiment of the present application, the embodiment of the present application is not limited to the electric turbocharger, and any supercharger that can achieve the above-described effects may be used, for example, an electric mechanical supercharger.
Fig. 2 is a structural diagram of an improved EGR system according to an embodiment of the present application, and as shown in fig. 2, the EGR system according to an embodiment of the present application includes an engine, a turbocharger, an electric turbocharger 7, an air cleaner 6, and an ECU, where:
the engine comprises an air inlet main pipe 3 and an air outlet main pipe 2, and further comprises an engine body 1;
the turbocharger comprises a turbine 4 and a compressor 5, wherein the compressor 5 is provided with an exhaust port and an air inlet, and the turbine 4 is provided with the exhaust port and the air inlet;
The air inlet of the turbocharger turbine 4 is connected with the exhaust manifold 2 of the engine, and when the exhaust gas is discharged from the exhaust manifold 2 of the engine, the exhaust gas enters the turbocharger turbine 4 through the air inlet and drives the turbine to operate, and the turbocharger pressurizes the exhaust gas in the turbine and then discharges the exhaust gas from the exhaust port;
meanwhile, an air inlet of a compressor 5 of the turbocharger is connected with the air filter 6, and an air outlet of the compressor 5 of the turbocharger is connected with an air inlet manifold 3 of the engine;
when the turbine 4 is operated by the exhaust gas, the compressor is driven to operate, filtered outside air is taken from the air cleaner, and the taken outside air is transmitted to the intake manifold 3 of the engine through the exhaust port of the compressor 5.
An exhaust port of the turbine 4 of the turbocharger is connected to an intake port of the electric turbocharger 7; an exhaust port of the electric turbocharger 7 is connected to an intake manifold 3 of the engine;
As shown in fig. 2, in the embodiment of the present application, an electric turbocharger 7 is added to the EGR system, the intake port of the electric turbocharger 7 is connected to the exhaust port of the turbine 4 of the turbocharger, exhaust gas is taken from the exhaust port of the turbine 4 in operation, the exhaust port of the electric turbocharger 7 is connected to the intake manifold 3 of the engine, and the taken exhaust gas is transferred to the intake manifold 3 of the engine.
The ECU is connected to the engine (engine block 1) and the electric turbocharger 7, and controls the engine and the electric turbocharger 7 according to a set control strategy so that the engine and the electric turbocharger 7 operate according to a set requirement.
According to the EGR system provided by the embodiment of the application, the electric turbocharger 7 is added, the exhaust gas is obtained from the exhaust port of the turbine 4 through the electric turbocharger 7, and then the exhaust gas is transmitted to the air inlet manifold 3 of the engine, so that the turbocharger only needs to consider the requirement of engine performance when matching, and the problem of taking EGR gas is not required, more than one can be properly matched, the performance oil consumption of the high-speed region of the engine and the altitude capability of the engine are considered, the performance of the engine is improved to the greatest extent, the control strategy is simple and easy to realize through the method of taking gas through the electric turbocharger 7, the work of the turbocharger is not influenced, and the dynamic property of the engine is improved.
In some embodiments, the EGR system further comprises an EGR mixer 9;
The EGR mixer 9 includes a first intake port, a second intake port, and an exhaust port; the exhaust port of the compressor 5 of the turbocharger is connected to the first intake port of the EGR mixer 9; the exhaust port of the electric turbocharger 7 is connected to the second intake port of the EGR mixer 9; the exhaust port of the EGR mixer 9 is connected to the intake manifold 3 of the engine.
The EGR mixer 9 is for sufficiently mixing the external air inputted therein through the first air inlet and the exhaust gas inputted therein through the second air inlet, and discharging the mixture through the exhaust port;
In some embodiments, the EGR system further includes an intake heating grid 12; the exhaust port of the EGR mixer 9 is connected to the intake manifold 3 of the engine through the intake heating grill 12. The intake heating grill 12 heats the gas discharged from the EGR mixer 9, and inputs the heated gas to a set temperature into the intake manifold 3 of the engine.
In some embodiments, the EGR system described above further includes an EGR cooler 8; the exhaust port of the electric turbocharger 7 is connected to the second intake port of the EGR mixer 9 via the EGR cooler 8. The EGR cooler 8 is used to cool the exhaust gas discharged from the electric turbocharger 7.
In some embodiments, the EGR system described above further includes an intercooler 10; the exhaust port of the compressor 5 of the turbocharger is connected to the first inlet port of the EGR mixer 9 via the intercooler 10. The intercooler 10 is used for cooling the outside air discharged from the compressor 5.
In some embodiments, the EGR system further includes and throttle 11; the throttle valve 11 is connected between the intercooler 10 and the first intake port of the EGR mixer 9, and controls the flow rate of the gas flowing into the engine intake manifold 3. Wherein, the throttle valve 11 is connected with the ECU, and the opening and closing degree of the throttle valve is controlled by the ECU.
In some embodiments, the EGR system further includes a plurality of detection devices; the ECU is also connected with the plurality of detection devices and used for acquiring the state parameters measured by the plurality of detection devices and controlling the exhaust gas recirculation system according to the state parameters.
The above-mentioned state parameters include, but are not limited to, parameters such as temperature, flow rate, pressure of the gas, rotational speed of the electric turbocharger, and the like.
In some embodiments, the plurality of detection devices specifically includes:
a pre-vortex pressure sensor 17, which is installed on the exhaust manifold 2 of the engine, and is used for measuring the gas pressure in the exhaust manifold 2 of the engine and sending the measured gas pressure value to the ECU;
An intake air temperature and pressure sensor 15 installed on an intake manifold 3 of the engine for measuring a gas temperature and a gas pressure in the intake manifold 3 of the engine and transmitting the measured gas temperature value and gas pressure value to an ECU;
a rotation speed sensor 18, which is mounted on the electric turbocharger 7, and which measures the rotation speed of the electric turbocharger 7 and sends the measured rotation speed to the ECU;
A venturi flowmeter 13 installed between the electric turbocharger 7 and the EGR mixer 9, for measuring a gas flow rate at an exhaust port of the electric turbocharger 7, and transmitting the measured gas flow rate value to the ECU;
Differential pressure sensors 14 installed at both sides of the venturi flow meter 13 for measuring differential pressure at both sides of the venturi flow meter 13 and transmitting the measured differential pressure of gas to the ECU;
A temperature sensor 16, which is installed between the EGR cooler 8 and the EGR mixer 9, measures the temperature of the gas discharged from the EGR cooler 8, and sends the measured gas temperature value to the ECU.
The detection device is not limited to the sensor and the flowmeter, and other types of devices capable of measuring the state parameter may be used instead of the detection device.
The embodiment of the application also provides an EGR system control method which is applied to the ECU of the EGR system provided by the embodiment of the application, as shown in figure 3, and specifically comprises the following steps:
Step 301, acquiring state parameters measured by a plurality of detection devices in an exhaust gas recirculation system;
And step 302, controlling the exhaust gas recirculation system according to the state parameter.
In the EGR system control method, the electric turbocharger 7 may be controlled by the real-time gas flow rate measured by the venturi flow meter 13 and the real-time rotational speed of the electric turbocharger 7 measured by the rotational speed sensor 18.
Fig. 4 and fig. 5 are schematic diagrams of a control principle of an electric turbocharger and a flow chart of a control method of the electric turbocharger in an EGR system according to an embodiment of the present application, referring to fig. 4 and fig. 5, a process for controlling the electric turbocharger in the embodiment of the present application specifically includes:
Step 501, acquiring real-time gas flow of an exhaust port of an electric turbocharger in an EGR system measured by a venturi flowmeter and real-time rotating speed of the electric turbocharger measured by a rotating speed sensor;
Step 502, performing difference between the real-time gas flow and a preset gas flow, and calculating a set rotation speed of the electric turbocharger by using a PID (proportion integration differentiation) based on the difference between the real-time gas flow and the preset gas flow;
The preset gas flow is a preset gas flow set value of an exhaust port of the electric turbocharger, and the value can be modified in real time according to the actual rotating speed and the requirement of the engine.
Step 503, calculating a motor duty ratio of the electric turbocharger by using a PID based on a difference between the real-time rotational speed and the obtained set rotational speed by making a difference between the real-time rotational speed and the set rotational speed;
step 504, controlling the electric turbocharger according to the motor duty cycle.
And after the motor duty ratio is calculated, controlling the motor in the electric turbocharger according to the motor duty ratio, wherein the larger the motor duty ratio is, the faster the running speed of the electric turbocharger is.
It should be noted that, the parameters used in the two PID calculation processes are set according to the operation condition of the EGR system, and may be modified according to the calculation result in the operation process of the EGR system.
In addition, the EGR system provided in the embodiment of the present application is not limited to the control method of the EGR system, and other control methods in the prior art may be used to control the EGR system in the embodiment of the present application.
The embodiment of the application also provides a vehicle which comprises the EGR system and the ECU, and the ECU controls the EGR system according to the EGR control method during operation.
The ECU consists of a microcontroller, a memory, an input/output interface, an analog-to-digital converter, a shaping and driving large-scale integrated circuit and the like.
And a memory for storing a computer program executed by the microcontroller. The memory can mainly comprise a memory program area and a memory data area, wherein the memory program area can store an operating system, programs required by running instant messaging functions and the like; the storage data area can store various instant messaging information, operation instruction sets and the like.
The memory may be a volatile memory (RAM), such as a random-access memory (RAM); the memory 1501 may also be a nonvolatile memory (non-volatile memory), such as a read-only memory, a flash memory (flash memory), a hard disk (HARD DISK DRIVE, HDD) or a solid state disk (solid-state drive-STATE DRIVE, SSD); or any other medium that can be used to carry or store a desired computer program in the form of instructions or data structures and that can be accessed by a computer. The memory may be a combination of the above memories.
A microcontroller may include one or more central processing units (central processing unit, CPU) or a digital processing unit, or the like. And the microcontroller is used for controlling the EGR system when calling the computer program stored in the memory.
The embodiment of the application is not limited to the specific connection medium among the devices such as the microcontroller, the memory, the input/output interface, the analog-to-digital converter and the like. The embodiment of the application uses the bus connection between the memory and the microcontroller, and the connection mode between other components is only illustrative and not limited by the way. The buses may be divided into address buses, data buses, control buses, etc.
The memory stores a computer storage medium in which computer executable instructions are stored for implementing the control of the EGR system according to the embodiment of the present application. The microcontroller is used for executing the EGR system control method to realize control of the EGR system.
In some possible embodiments, aspects of the EGR system control method provided by the present application may also be implemented in the form of a program product comprising a computer program for causing an ECU to execute the steps in the EGR system control method according to the various exemplary embodiments of the present application described above when the program product is run on an electronic device.
The program product may employ any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium would include the following: an electrical connection having one or more wires, a portable disk, a hard disk, random Access Memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.
The program product of an embodiment of the present application may employ a portable compact disc read only memory (CD-ROM) and include a computer program and may run on the ECU. However, the program product of the present application is not limited thereto, and in this document, a readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with a command execution system, apparatus, or device.
The readable signal medium may comprise a data signal propagated in baseband or as part of a carrier wave in which a readable computer program is embodied. Such a propagated data signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination of the foregoing. A readable signal medium may also be any readable medium that is not a readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with a command execution system, apparatus, or device.
A computer program embodied on a readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.
Computer programs for performing the operations of the present application may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer program may be executed entirely, partly, as a stand-alone software package.
It should be noted that although several units or sub-units of the apparatus are mentioned in the above detailed description, such a division is merely exemplary and not mandatory. Indeed, the features and functions of two or more of the elements described above may be embodied in one element in accordance with embodiments of the present application. Conversely, the features and functions of one unit described above may be further divided into a plurality of units to be embodied.
Furthermore, although the operations of the methods of the present application are depicted in the drawings in a particular order, this is not required or suggested that these operations must be performed in this particular order or that all of the illustrated operations must be performed in order to achieve desirable results. Additionally or alternatively, certain steps may be omitted, multiple steps combined into one step to perform, and/or one step decomposed into multiple steps to perform.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Furthermore, the present application may take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having a computer-usable computer program embodied therein.
While preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.