Summary of the invention
The application is intended to improve the metering of air input of engine by air, and the back pressure wherein in outlet pipe is counted into, thus the amount of fresh air of metering engine introducing more accurately.
According to an aspect of the application, providing a kind of for being equipped with the air inlet batching unit of motor, the especially diesel engine of exhaust gas re-circulation apparatus, comprising:
Inlet condition detector, which is connected engine air inlet tube, for detecting suction tude inlet condition;
Back pressure detector, which is connected engine exhaust pipe, for detecting outlet pipe back pressure; And
Controller, which is connected motor, inlet condition detector and back pressure detector, and comprise the air inflow model of suction tude inlet condition and the outlet pipe back pressure detected based on engine structure parameter and Operational Limits and inlet condition detector and back pressure detector, described controller utilizes described air inflow model to determine to introduce the amount of fresh air in suction tude.
According to a kind of embodiments possible of the application, engine structure parameter comprises engine blow-through air efficiency and engine displacement, engine operating parameter comprises engine speed, and inlet condition detector comprises temperature transducer for detecting intake temperature in suction tude and pressure and pressure transducer.
According to a kind of embodiments possible of the application, exhaust gas processing device is provided with in described outlet pipe, its both sides have the pressure reduction changing (such as increasing gradually) with the operating time, described back pressure detector is differential pressure pickup, described differential pressure pickup detects the pressure reduction of exhaust gas processing device both sides, and the pressure reduction of exhaust gas processing device both sides is determined to be used as outlet pipe back pressure when introducing the amount of fresh air in suction tude at control gear.
According to a kind of embodiments possible of the application, control gear is based on formula determination amount of fresh air below:
Mfresh＝λ×Fac×V×n×Pmix×C/Tfresh-ab
Wherein, Mfreshfor amount of fresh air;
λ is the correction factor determined based on the outlet pipe back pressure measured in real time;
Fac is engine blow-through air efficiency;
V is engine displacement;
N is engine speed;
Pmixfor the suction pressure in engine air inlet tube;
C is the constant to engine calibration on Laboratory Furniture;
Tfresh-abfor the intake temperature in engine air inlet tube.
According to a kind of embodiments possible of the application, be provided with in suction tude to introduce fresh air supercharging gas compressor and be positioned at the intercooler of downstream for cool fresh air, the intake temperature in engine air inlet tube is by the temperature of the cooled fresh air of intercooler in suction tude; Further, the suction pressure in engine air inlet tube is the pressure of the mixed gas that fresh air is formed with the exhaust gas recirculation introduced in suction tude.
According to a kind of embodiments possible of the application, comprise in described air inflow model embody engine speed, Engine Injection Mass, back pressure rank, corresponding relation tables look-up and/or data and/or calculating formula between correction factor corrected value, to table look-up described in described control gear utilizes and/or data and/or calculating formula determine described correction factor, such as, described correction factor equals 1 and deducts correction factor corrected value corresponding to current exhaust pipe back pressure rank.
According to a kind of embodiments possible of the application, the scope of described correction factor between 0.7 and 1, preferably between 0.85 and 1.
According to a kind of embodiments possible of the application, described air inlet batching unit also comprises the fresh air throttle valve be arranged in suction tude, it is connected with control gear, and control gear measures the amount of fresh air introduced in suction tude by the aperture controlling fresh air throttle valve.
The application provides a kind of engine system, especially diesel engine system on the other hand at it, comprising:
Motor;
Be connected to suction tude and the outlet pipe of motor;
Exhaust gas recirculatioon pipe, it is connected between outlet pipe and suction tude, and a part for engine exhaust flows in suction tude through exhaust gas recirculatioon pipe;
Exhaust gas processing device, it produces back pressure in outlet pipe; And
Previously described air inlet batching unit, the amount of fresh air in suction tude is introduced in its metering.
According to a kind of embodiments possible of the application, described exhaust gas processing device is particulate filter, also arranges one or more in following apparatus: exhaust gas catalyst device, selective catalytic reduction device, ammonia filtrating equipment in described outlet pipe.
According to the application, when determining air input of engine by air, the impact of the back pressure in outlet pipe is counted into, to revise air input of engine by air, makes motor amount of fresh air obtain measuring more accurately, the metering of tail gas therefore also can be made more accurate.The after-treatment device control accuracy depending on tail gas amount and implement to control can be improved.The exhaust of motor can meet the requirement of high exhaust gas emission standard, such as, can reach Europe 6 emission standard.
Embodiment
The embodiments possible of the application is described with reference to the accompanying drawings.
Fig. 1 schematically shows the engine system of a mode of execution according to the application, and it mainly comprises motor 1, especially diesel engine, and is connected to suction tude L1 and the outlet pipe L2 of motor.
Arrange successively along the direction of inlet stream shown in arrow in suction tude L1: air-strainer 2, for filtering the fresh air introducing suction tude L1; Gas compressor 3, for the fresh air supercharging in suction tude L1; Intercooler 4, for cooling the fresh air in suction tude L1; And fresh air throttle valve 5, for carrying out throttling to the fresh air in suction tude L1.
Arrange successively from along the direction of exhaust stream shown in arrow in outlet pipe L2: exhaust driven gas turbine 6, it is coaxially arranged with gas compressor 3 and be connected, for rotation by the exhaust gas drive in outlet pipe L2, and drive gas compressor 3 to operate, exhaust driven gas turbine 6 and gas compressor 3 form a turbosupercharger; And be arranged in the exhaust gas processing device in exhaust driven gas turbine 6 downstream side.In the example in the figures, exhaust gas processing device comprises: exhaust gas catalyst device 7, such as diesel engine oxidation catalyst (DOC); Particulate filter 8, such as diesel particulate filters (DPF); Selective catalytic reduction (SCR) device 9; And ammonia filtrating equipment 10, such as NH_3 leakage catalyst converter (ASC).
In addition, between suction tude L1 and outlet pipe L2, arrange exhaust gas recirculatioon pipe L3, its upstream extremity L3a is connected to outlet pipe L2 in exhaust driven gas turbine 6 upstream, and downstream L3b is connected to suction tude L1 in fresh air throttle valve 5 downstream.Exhaust gas recirculation throttle valve 11 and the vent gas cooler 12 being positioned at exhaust gas recirculation throttle valve downstream is arranged in exhaust gas recirculatioon pipe L3.Like this, a part for the exhaust of motor 1 flows in suction tude L1 through exhaust gas recirculatioon pipe L3, mixes and produce the mixed gas be supplied in motor 1 with the fresh air in suction tude L1.
In addition, in suction tude L1, between intercooler 4 and fresh air throttle valve 5, temperature transducer 13 is arranged, for detecting in suction tude L1 by the temperature T of the cooled fresh air of intercooler 4fresh(DEG C).
In addition, in suction tude L1, between the downstream L3b and motor 1 of exhaust gas recirculatioon pipe L3, pressure transducer 14 is arranged, for detecting the pressure P of the mixed gas in suction tude L1mix.
In addition, in outlet pipe L2, back pressure detector is arranged, for detecting the back pressure in the outlet pipe L2 of exhaust driven gas turbine 6 downstream side.In the example in the figures, the form of this back pressure detector is differential pressure pickup 15, its two ends are connected to the upstream and downstream of particulate filter 8, and for detecting the both sides pressure differential deltap P of particulate filter 8, the exhaust stream namely in outlet pipe L2 is through the pressure drop of particulate filter 8.Due in the example in the figures, the back pressure in the outlet pipe L2 of exhaust driven gas turbine 6 downstream side is mainly caused by particulate filter 8, and therefore the pressure reduction of particulate filter 8 both sides can be taken as outlet pipe back pressure and uses.But, be appreciated that, according to other mode of execution of the application, the exhaust gas processing device of other form may be arranged in exhaust driven gas turbine 6 downstream side in outlet pipe, therefore, be appreciated that and the back pressure detector of appropriate format can be adopted to detect the back pressure in the outlet pipe L2 of exhaust driven gas turbine 6 downstream side.
In addition, engine system comprises controller 16, which is connected motor 1, fresh air throttle valve 5, exhaust gas recirculation throttle valve 11, temperature transducer 13, pressure transducer 14, differential pressure pickup 15 (or back pressure detector of other form), for performing following operation: detect the working state of motor 1 and control the operation of motor 1; Receive valve position (aperture) signal of fresh air throttle valve 5, exhaust gas recirculation throttle valve 11, and control their operation; Receive the testing signal of temperature transducer 13, pressure transducer 14, differential pressure pickup 15.
Controller 16 is configured to determine based on the testing signal of temperature transducer 13, pressure transducer 14, differential pressure pickup 15 the amount of fresh air M that enters in suction tude L1fresh.Like this, controller 16, temperature transducer 13, pressure transducer 14, differential pressure pickup 15 constitute the engine charge batching unit of the application.
Can find out, the engine charge batching unit of the application is when determining air input of engine by air, and in outlet pipe, the impact of back pressure is counted into.In order to explain the effectiveness of this measure of the application, first the impact of back pressure in outlet pipe on the indices of engine system is tested, referring to the plotted curve in Fig. 2-7.It may be noted that in figures 2-7 which, abscissa is outlet pipe back pressure, represents with the both sides pressure differential deltap P of particulate filter 8, and the longitudinal axis is some indexs of engine system.The increase of outlet pipe back pressure illustrates that the amount of particulate matter in the engine exhaust of trapping in particulate filter 8 increases.
These tests are when engine system is run, and carry out under the condition adopting traditional fresh air metering method (namely only counting the impact of the pressure being mixed the mixed gas produced by the temperature of the cooled fresh air of intercooler and fresh air with exhaust gas recirculation) to control engine charge.
The relation of outlet pipe back pressure and exhaust gas recirculation rate (EGR rate) is shown in Fig. 2.Namely EGR rate is back to by exhaust gas recirculatioon pipe L3 the mass ratio that engine exhaust in suction tude L1 and motor 1 enter the whole exhausts in outlet pipe L2.Can see, along with outlet pipe back pressure increases, EGR rate increases, thus the air displacement be recycled in suction tude L1 increases, and is supplied to exhaust gas recirculation proportion in the fresh air of motor 1 and the mixed gas of exhaust gas recirculation and increases.Along with the increase of EGR rate, more favourable to reduction NOx emission.But EGR rate is larger, fuel consumption rate also will increase, and this power character to motor, Economy have adverse effect.
Relation between the smoke intensity of the tail gas showing outlet pipe back pressure in Fig. 3 and discharge from outlet pipe L2.Can see, along with outlet pipe back pressure increases, the smoke intensity of tail gas increases.Therefore, although NOx discharge reduces, and do not mean that exhaust emissions quality just increases.
The pressure P of the mixed gas in outlet pipe back pressure and suction tude L1 is shown in Fig. 4mixbetween relation.Can see, along with outlet pipe back pressure increases, engine charge pressure slightly declines, and this can cause engine power to decline.
Show outlet pipe back pressure in Fig. 5 and detect in suction tude L1 by the temperature T of the cooled fresh air of intercooler 4freshbetween relation.Can see, the temperature impact of outlet pipe economy on the fresh air of input is little.
The difference between the theoretical amount of fresh air (top curve) of the motor when outlet pipe economy and actual fresh air quantity (lower curve) is shown in Fig. 6.Theoretical amount of fresh air is in the amount of fresh air adopting traditional fresh air metering method (not counting the impact of outlet pipe back pressure) to determine.Actual fresh air quantity is the amount of fresh air of motor effective supply based on engine operating condition after the impact counting outlet pipe back pressure.Can find out, actual fresh air quantity is less than theoretical amount of fresh air.The relation between outlet pipe back pressure and actual fresh air quantity error is shown in Fig. 7.Can see, along with outlet pipe back pressure increases, the error between theoretical amount of fresh air and actual fresh air quantity is larger.
As can be seen from experimental result above, outlet pipe economy has substantial impact for the performance of motor and exhaust emissions quality.Based on this unheeded factor in the prior art, the application proposes, and when determining the amount of fresh air that motor is introduced, counts the outlet pipe back pressure measured in real time.According to an embodiment of the application, adopt the amount of fresh air that following formulae discovery motor is introduced:
Mfresh＝λ×Fac×V×n×Pmix×C/Tfresh-ab
Wherein, Mfreshthe amount of fresh air (kg/h) that during for counting tracheae back pressure, motor is introduced;
λ is the correction factor after counting the outlet pipe back pressure that measures in real time;
Fac is engine blow-through air efficiency, can be provided by tabling look-up that test stand is demarcated;
V is engine displacement;
N is engine speed (rpm);
Pmixfor the pressure (such as being detected by pressure transducer 14) of the mixed gas in engine air inlet tube;
C is constant, can demarcate on test stand;
Tfresh-abfor in engine air inlet tube by the cooled fresh air temperature of intercooler (such as being detected by temperature transducer 13), unit is kelvin temperature, equals Tfreshthe value of (DEG C) adds 273.
Above-mentioned formula can be abbreviated as:
Mfresh＝λ×Mfresh0
Wherein Mfresh0=Fac × V × n × Pmix× C/Tfresh-ab, can be regarded as particulate filter brand-new time motor introduce amount of fresh air, i.e. amount of fresh air initial value.
Correction factor λ and amount of fresh air M is introduced below in conjunction with Fig. 1, Fig. 8freshdeterministic process.It may be noted that each several part in the air input of engine by air model in Fig. 8 is integrated or be stored in controller 16 with the form of hardware and/or software.
First, based on the both sides pressure differential deltap P of the signal determination present granule filter 8 of differential pressure pickup 15; Serviceability such as rotating speed and fuel injection quantity based on motor 1 utilize the pressure reduction under particulate filter 8 zero load (namely particulate filter 8 is for new, does not collect any exhaust particulate) state to table look-up to draw the both sides pressure differential deltap P0 under particulate filter 8 unloaded state; The pressure reduction under fully loaded (namely having filled exhaust particulate in the particulate filter 8) state of particulate filter 8 is utilized to table look-up the both sides pressure differential deltap P1 drawn under particulate filter 8 full load condition based on the serviceability such as rotating speed and fuel injection quantity of motor 1; Calculate pressure reduction rate=(Δ P-Δ P0)/(the Δ P-Δ P1) of present granule filter 8.
Meanwhile, utilize correction factor to table look-up to draw the correction factor corrected value under particulate filter 8 full load condition based on the serviceability such as rotating speed and fuel injection quantity of motor 1.
Next, the pressure reduction rate of present granule filter 8 is multiplied with the correction factor under particulate filter 8 full load condition, draws the correction factor correction value delta λ under present granule filter 8 state.
Next, correction factor correction value delta λ under this current particulate filter 8 state is judged whether between the correction factor corrected value maxima and minima allowed.If this Δ λ between the correction factor corrected value maxima and minima allowed, then adopts this Δ λ.If this Δ λ is greater than the correction factor corrected value maximum value of permission or is less than the correction factor corrected value minimum value of permission, then Δ λ gets the correction factor corrected value maximum value of permission or the correction factor corrected value minimum value of permission.
Next, correction factor λ=1-Δ λ is drawn.Because correction factor corrected value has maxima and minima, therefore correction factor also has corresponding minimum value and maximum value.The pratical and feasible scope of correction factor between 0.7 and 1, preferably between 0.85 and 1.
Next, actual amount of fresh air M is obtainedfresh=λ × Mfresh0.
The amount of fresh air M obtained by the wayfreshfor having counted the exact value of the amount of fresh air after outlet pipe back pressure.Therefore, according to the application, the amount of fresh air of precise volume can be provided to motor 1, make when outlet pipe economy, maintain power character, the Economy of motor, and keep tail gas index to meet corresponding standard, such as, Europe 6 emission standard can be met.
Each in air inflow model above-mentioned is tabled look-up and can be demarcated on test stand, and is stored in controller 16.As an alternative or additional, other is tabled look-up and/or corresponding data and/or corresponding calculating formula can be included in air inflow model, in order to determine correction factor and amount of fresh air.
The amount of fresh air introduced in suction tude L1 controls by control gear 16, such as, by controlling the aperture of fresh air throttle valve 5.Or other flow control device can be arranged in suction tude L1 and controlled device 16 controls, to realize required amount of fresh air.
In the amount of fresh air deterministic process introduced above, engine blow-through air efficiency, discharge capacity are used as the example of engine structure parameter, engine speed is used as the example of engine operating parameter, is used in suction tude by the pressure of the mixed gas in the cooled fresh air temperature of intercooler, suction tude as suction tude inlet condition.Be appreciated that as an alternative or additional, other engine structure and Operational Limits, suction tude inlet condition (being detected by corresponding suction tude inlet condition detector) also can be used in the amount of fresh air deterministic process of the application.Such as, can be replaced with the temperature of the mixed gas in suction tude in suction tude by the cooled fresh air temperature of intercooler, the pressure of the mixed gas in suction tude can be replaced by the fresh air pressure after compressor pressure.In other engine structure and Operational Limits, the adopted situation of suction tude inlet condition, only need demarcate constant C on Laboratory Furniture.
Can see, the engine charge batching unit of the application provides a kind of new air input of engine by air model, and wherein the change (pressure reduction of the particulate filter under such as zero load and full load condition) of outlet pipe back pressure is counted into.In the motor amount of fresh air determination formula of the application, carry out interpolation calculation to determine the correction factor of air inflow model based on the linear relationship between back pressure and correction factor.
It may be noted that, with reference to described by Fig. 8 before the air inflow model of the application is not limited to, but be applicable to the various air inflow models that those skilled in the art can set up based on engine structure parameter and Operational Limits, suction tude inlet condition and outlet pipe back pressure.And, the determination of the amount of fresh air of the application is not limited to the formula that utilization introduces above and calculates, but can determine based on specific engine type, operating mode the amount of fresh air formula being suitable for this motor, the validity of this formula can be verified on Laboratory Furniture.In addition, the correction factor of the application is not limited to calculate based on the linear relationship between back pressure and correction factor as previously mentioned and obtains, but based on function relations between factor structure back pressure and correction factor such as specific engine type, operating mode, exhaust emissions requirements, correction factor can be obtained thus.
The differential pressure pickup (or back pressure detector of other form) of particulate filter both sides is have employed to provide outlet pipe back pressure signal in the motor amount of fresh air determination scheme of the application.Integrated air input of engine by air model is in the controller used for air input of engine by air metering.This application provides engine system, the amount of fresh air metered scheme that cost is lower, precision is higher such as with the diesel engine of particulate filter.
Although describe the application with reference to concrete mode of execution here, the scope of the application is not limited to shown details.When not departing from the basic principle of the application, various amendment can be made for these details.