Air flow meter signal delay compensation device for engine transient air-fuel ratio

Abstract

The invention relates to the technical field of engine control, in particular to air flow meter signal delay compensation equipment for the transient air-fuel ratio of an engine. Comprising a data acquisition device which comprises sensors arranged in N sections of gas inlet pipes from the gas inlet front end of an engine to a gas inlet valve of the engine and is used for acquiring gas parameters in the multiple sections of gas inlet pipes; n is a positive integer; the delay calculation device is connected with the data acquisition device and obtains total delay time based on the gas parameters; and the delay chip is connected with the delay calculation device and controllably superposes the total delay time to the air flow meter, and the air flow meter outputs delayed flow meter signals. According to the method, the gas parameters of the multiple sections of gas inlet pipes are collected through the sensors, the time of gas passing through each section of gas inlet pipe is calculated, the total delay time between the gas inlet front end of the engine and the gas inlet valve of the engine is obtained, the total delay time is considered into the coordination advance in engine transient control, and the overshoot risk in the prior art is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of engine control, and in particular to an air flow meter signal delay compensation device for the transient air-fuel ratio of an engine. Background Art

[0002] The transient control of the engine air-fuel ratio is a relatively complex control for the engine management system, and the quality of transient control is crucial to the drivability of the entire vehicle. The traditional engine air-fuel ratio control is that the engine control unit (ECU) uses the engine intake pressure sensor as a signal source to estimate the current engine intake volume and the corresponding load to perform corresponding injection control, and uses the feedback signal of the exhaust end oxygen sensor to perform closed-loop adjustment in real time to achieve the purpose of vehicle emissions and comfortable driving.

[0003] Due to the diversity of vehicle operating conditions, the engine cannot always be in a stable operating condition. In most cases, the engine speed and load are always in transient changes, such as starting, acceleration and deceleration, etc. The above logic is not timely and forward-looking in the estimation and control of the transient intake volume of the engine, resulting in inaccurate fuel injection under transient conditions, abnormal engine combustion, affecting the driving experience of the vehicle and related pollutant emissions.

[0004] At present, the common control strategy of ECU in the market is to use the signal read by the air flow meter for direct control after filtering, which is not good for transient control, because the air flow meter is generally installed at the front end of the engine intake, far away from the engine intake valve, and there will be a certain risk of "over-advance" overshoot if the signal is directly used for fuel injection; at the same time, since the change of engine working conditions comes from the driver's demand for engine torque, a certain amount of advance is also required to calculate the target intake flow rate according to the driver's demand (accelerator pedal), so there is also an advance amount for the current actual intake volume of the engine. Therefore, the existing technology will cause the problem that the current actual intake volume of the engine does not match the target intake flow rate. Summary of the invention

[0005] The purpose of the present invention is to provide an air flow meter signal delay compensation device for the transient air-fuel ratio of an engine to solve the above technical problems;

[0006] The technical problem solved by the present invention can be achieved by adopting the following technical solutions:

[0007] An air flow meter signal delay compensation device for an engine transient air-fuel ratio comprises an air flow meter disposed at the front end of an engine intake, and further comprises:

[0008] The data acquisition device includes sensors disposed in N sections of the intake pipe from the engine intake front end to the engine intake valve, and acquires gas parameters in the multiple sections of the intake pipe; N is a positive integer;

[0009] A delay calculation device, connected to the data acquisition device, and obtaining a total delay time based on the gas parameters;

[0010] The delay chip is connected to the delay calculation device and can controllably add the total delay time to the air flow meter, and the air flow meter outputs a delayed flow meter signal.

[0011] Preferably, the sensor includes a pressure sensor, a corresponding pressure sensor is provided in the air intake pipe, and the gas parameter includes at least the gas pressure.

[0012] Preferably, it also includes a volume database connected to the delay calculation device, the volume database stores the volume value of each section of the intake pipe, and the delay calculation device calculates the delay time corresponding to each section of the intake pipe based on the volume value and the gas pressure.

[0013] Preferably, the delay calculation device is provided with an adder to obtain the total delay time based on the addition of N sections of the intake delay time.

[0014] Preferably, the air intake pipe comprises:

[0015] A first section of the intake pipe from the engine intake front end to the supercharger;

[0016] a second section of the intake pipe from the supercharger to the throttle body of the engine intake manifold;

[0017] A third section of the intake pipe extends from the throttle body to the engine intake valve.

[0018] Preferably, the air flow meter is provided with a pressure sensor chip to obtain the gas pressure of the first section of the intake pipe, and the pressure sensor includes a first pressure sensor arranged in the second section of the intake pipe and a second pressure sensor arranged in the third section of the intake pipe.

[0019] Preferably, the sensor further includes a temperature sensor for detecting the temperature in the intake pipe.

[0020] Preferably, it also includes a target intake flow calculation device connected to the air flow meter, the target intake flow calculation device receives an external torque signal, and calculates and obtains a target intake flow for adapting the delayed flow meter signal based on a preset torque-intake flow mapping relationship.

[0021] Preferably, the air flow meter is also provided with a waveform recorder for recording the flow meter signal of the air flow meter, the delay chip is connected to the waveform recorder, and the waveform recorder outputs the delayed flow meter signal based on the superimposed total delay time.

[0022] Preferably, the air flow meter is further provided with a signal processing chip, and the signal processing chip can controllably pre-process the delayed flow meter signal.

[0023] Beneficial effects of the present invention: Due to the adoption of the above technical scheme, the present invention collects gas parameters of multiple intake pipes through sensors, calculates the time for gas to pass through each intake pipe, obtains the total delay time between the engine intake front end to the engine intake valve, and takes the total delay time into account to coordinate the advance amount in the engine transient control, avoiding the risk of overshoot due to "over-advance" in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural diagram of an air flow meter signal delay compensation device for an engine transient air-fuel ratio in an embodiment of the present invention;

[0025] Figure 2 It is a structural diagram of an air flow meter signal delay compensation device for the transient air-fuel ratio of an engine in an embodiment of the present invention.

[0026] Figure 3 Schematic diagram of a delayed flow meter signal in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0029] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0030] Air flow meter signal delay compensation device for engine transient air-fuel ratio, such as Figure 1 , Figure 2 , Figure 3 As shown, it includes an air flow meter 1 arranged at the front end of the engine intake, and also includes,

[0031] The data acquisition device 2 includes sensors disposed in N sections of the intake pipe from the engine intake front end to the engine intake valve, to obtain gas parameters in the multiple sections of the intake pipe; N is a positive integer;

[0032] The delay calculation device 3 is connected to the data acquisition device 2 and obtains the total delay time based on the gas parameters;

[0033] The delay chip 4 is connected to the delay calculation device 3 and can controllably add the total delay time to the air flow meter 1, so that the air flow meter 1 outputs a delayed flow meter signal.

[0034] Specifically, the present invention aims at the risk of overshoot due to "over-advance" when the air flow meter 1 is installed at the front end of the engine intake in the prior art; the advance amount is coordinated to make the transient control of the engine based on the flow meter signal more accurate. The present invention delays the actual signal reading of the air flow meter 1 by estimating the volume from the flow meter to the engine intake valve, and balances the delayed signal with the target flow calculated according to the engine's required torque to calculate the true transient intake volume.

[0035] The present invention is applicable to an engine control system that is equipped with an air flow meter 1 signal regardless of whether it is equipped with an intake air temperature sensor or not. The present invention optimizes the engine transient control by performing transient control based on the signal of the air flow meter 1, thereby ultimately achieving the purpose of optimizing vehicle drivability and emissions.

[0036] The present invention collects data such as intake manifold pressure and temperature, boost pressure, intake pressure, temperature and flow at the air flow meter 1 (AFM), engine speed, and charging efficiency, and can use the calibration tool INCA in conjunction with the bench calibration tool PUMA to collect the data.

[0037] The air intake section of the present invention is divided into three sections, namely, between the air flow meter 1 and the supercharger 5, between the supercharger 5 and the throttle body 6, and between the throttle body 6 and the engine intake valve. According to the pressure, temperature and volume of different sections, the gas passage time is calculated respectively using a flow calculation formula and the final delay is added up, which is updated in real time and periodically through a software method.

[0038] Based on the target intake volume and the delayed flow meter signal, filtering and delay processing are performed to balance the delayed signal with the target flow calculated according to the engine demand torque, thereby calculating the true transient intake volume.

[0039] The present invention is applicable to a system equipped with an air flow meter 1, and can realize precise control of transient engine operating conditions, thereby effectively improving vehicle drivability and emission effects.

[0040] In a preferred embodiment, the sensor includes a pressure sensor, a corresponding pressure sensor is provided in the intake pipe, and the gas parameter includes at least the gas pressure.

[0041] Specifically, the present invention adopts the flow formula to calculate the delay, and its principle is as follows:

[0042] First, the ideal gas state equation is:

[0043] pV=nRT

[0044] Where p is the gas pressure, V is the gas volume, n is the amount of substance, R is the ideal gas constant, and T is the gas temperature (in Kelvin).

[0045] The mass flow rate calculation formula is,

[0046] m=ρvA

[0047] Where m is the mass flow rate, ρ is the gas density, v is the air velocity, and A is the cross-sectional area of ​​the intake pipe;

[0048] According to the density-mass formula,

[0049]

[0050] The volume flow rate relationship of the gas flowing in the pipeline is:

[0051] V=vA

[0052] The gas density ρ can be obtained by transforming the ideal gas state equation, the expression is,

[0053]

[0054] Where M is the molar mass of the gas.

[0055] Combined with the mass flow formula,

[0056]

[0057] The formula for calculating the gas passage time of each section is:

[0058]

[0059] This formula represents the time required for gas to pass through a certain section of the intake pipe, where t represents the delay time, V represents the volume of the section of the intake pipe, and Q is the volume flow rate through the section of the pipe, which is calculated using the above volume flow calculation formula.

[0060] More specifically, the present invention divides the air intake pipe into three sections, including:

[0061] A first section of the air intake pipe 7 from the front end of the engine air intake to the supercharger 5;

[0062] A second section of the intake pipe 8 from the supercharger 5 to the throttle body 6 of the engine intake manifold;

[0063] The third section of the intake pipe 9 from the throttle body 6 to the engine intake valve.

[0064] Calculate the gas passage time t1, t2, t3 of each section respectively, and then add them together to get the final total delay time T, that is,

[0065] T=t1+t2+t3.

[0066] In a preferred embodiment, it also includes a volume database connected to the delay calculation device 3, the volume database stores the volume value of each section of the intake pipe, and the delay calculation device 3 calculates the delay time corresponding to each section of the intake pipe based on the volume value and the gas pressure.

[0067] Specifically, the present invention divides the entire intake section into three sections according to the structural characteristics of the intake system, including:

[0068] A first section of the air intake pipe 7 from the front end of the engine air intake to the supercharger 5;

[0069] A second section of the intake pipe 8 from the supercharger 5 to the throttle body 6 of the engine intake manifold;

[0070] The third section of the intake pipe 9 from the throttle body 6 to the engine intake valve.

[0071] The present invention comprehensively considers the characteristics of each section of the air intake pipe and performs delay calculation respectively, and then obtains the total delay time by calculating the gas passing time of each section.

[0072] In a preferred embodiment, an adder is provided in the delay calculation device 3 to obtain a total delay time based on the addition of N intake delay times.

[0073] In a preferred embodiment, the air intake pipe includes:

[0074] A first section of the air intake pipe 7 from the front end of the engine air intake to the supercharger 5;

[0075] A second section of the intake pipe 8 from the supercharger 5 to the throttle body 6 of the engine intake manifold;

[0076] The third section of the intake pipe 9 from the throttle body 6 to the engine intake valve.

[0077] In a preferred embodiment, the air flow meter 1 is provided with a pressure sensor chip to obtain the gas pressure of the first section of the intake pipe 7, and the pressure sensor includes a first pressure sensor 21 provided in the second section of the intake pipe 8 and a second pressure sensor 22 provided in the third section of the intake pipe 9.

[0078] Specifically, the present invention reflects the real-time working status of the engine intake system by collecting data such as intake manifold pressure and temperature, boost pressure, intake pressure, temperature and flow at the air flow meter 1 (AFM), engine speed, and charging efficiency.

[0079] Data collection is performed using the calibration tool INCA in conjunction with the bench calibration tool PUMA.

[0080] According to the structural characteristics of the intake system, the present invention divides the entire intake section into three sections. The first section is the volume between the air flow meter 1 and the supercharger 5, the second section is the volume between the supercharger 5 and the throttle body 6, and the third section is the volume between the throttle body 6 and the engine intake valve. The segmentation method of the present invention is based on the different effects of different components in the intake system on the airflow, and considering that the pressure, temperature and volume change laws in each section are also different, the above-mentioned segmentation method is adopted.

[0081] For each section, the gas passage time is calculated according to the flow calculation formula.

[0082] Taking the first section of the intake pipe 7 as an example, assuming that the volume V1 between the air flow meter 1 and the supercharger 5 is:

[0083] First, according to the ideal gas state,

[0084] p1V1=nRT1

[0085] Calculate the density p1 of the gas in the first section of the intake pipe 7, where p1 is the gas pressure in the section, V1 is the volume of the section, n is the amount of substance, R is the ideal gas constant, and T1 is the intake temperature of the section (in Kelvin).

[0086] Transformation is available,

[0087]

[0088] Then, according to the mass flow calculation formula,

[0089] m1=ρ1v1A1

[0090] Wherein, m1 is the mass flow rate of this section, ρ1 is the gas density of this section, v1 is the air flow rate of this section, and A1 is the cross-sectional area of ​​the first section of the intake pipe 7;

[0091] Combined with the gas density formula, the volume flow rate can be further obtained.

[0092]

[0093] Finally, according to the formula,

[0094]

[0095] The time t1 for the gas to pass through the first section of the intake pipe 7 is calculated.

[0096] Similarly, the gas passage times t2 and t3 of the second section of the air intake pipe 8 (with a volume of V2) and the third section of the air intake pipe 9 (with a volume of V3) can be calculated in the same way.

[0097] By adding up the gas passage time of the three sections of the intake pipe, the total delay time T is finally obtained.

[0098] T=t1+t2+t3.

[0099] In order to adapt to the real-time changes in the engine operating conditions, the present invention uses a software method to perform real-time periodic updates on the calculation results to ensure accurate calculation of the delay time.

[0100] In a preferred embodiment, the sensor further comprises a temperature sensor for detecting the temperature in the intake pipe.

[0101] In a preferred embodiment, it also includes a target intake flow calculation device connected to the air flow meter 1, the target intake flow calculation device receives an external torque signal, and calculates and obtains a target intake flow for adapting the delayed flow meter signal based on a preset torque-intake flow mapping relationship.

[0102] Specifically, in an actual engine system, the required parameters are obtained by using the above-mentioned data collection method, and the delays of each part of the intake section are calculated according to the gas flow formula. Under different working conditions (such as starting, acceleration and deceleration, etc.), the relationship between the flow meter signal and the target flow is processed according to the calculation results to achieve precise control of the transient air-fuel ratio of the engine, thereby improving driving experience and emission performance.

[0103] The present invention calculates the target intake flow rate based on the driver's demand for engine torque (obtained through sensor signals such as accelerator pedal position) and the engine's speed, load and other operating parameters using a preset torque-intake flow mapping relationship.

[0104] The torque-intake flow mapping relationship is determined during the engine bench test and vehicle calibration process, and is used to determine the optimal intake volume required by the engine under different torque requirements to ensure the engine's power, economy and emission performance under various operating conditions.

[0105] In a preferred embodiment, the air flow meter 1 is further provided with a waveform recorder for recording the flow meter signal of the air flow meter 1, the delay chip 4 is connected to the waveform recorder, and the waveform recorder outputs a delayed flow meter signal based on the superimposed total delay time.

[0106] In a preferred embodiment, the air flow meter 1 is further provided with a signal processing chip, and the signal processing chip can controllably pre-process the delayed flow meter signal.

[0107] Specifically, the signal processing chip performs filtering processing on the waveform signal collected by the air flow meter 1 to remove noise and interference in the signal and improve the accuracy of the signal. The filtering algorithm can adopt a common digital filtering method, such as Kalman filtering.

[0108] The present invention delays the filtered air flow meter 1 signal so that its delay time matches the estimated volume delay time from the flow meter to the intake valve. The delay processing can be implemented by a delay algorithm in digital signal processing technology.

[0109] Finally, the delayed flow meter signal is balanced with the target intake flow rate. The specific calculation method can be to dynamically adjust according to the difference between the two, such as using a proportional-integral-differential (PID) control algorithm, by continuously adjusting the injection pulse width and other control parameters, so that the actual intake volume gradually approaches the target intake flow rate, thereby calculating the true transient intake volume.

[0110] In a specific embodiment,

[0111] In this embodiment, on an engine test bench equipped with an air flow meter 1 and a supercharging system, the INCA calibration tool and the PUMA bench calibration tool are started, the data acquisition parameters are set, and the data such as the intake manifold pressure and temperature, boost pressure, AFM end intake pressure, temperature and flow, engine speed, and charging efficiency are started to be collected.

[0112] According to the technical specifications of the engine and the actual structural dimensions of the intake system, the volumes V1, V2 and V3 of the three sections of the intake section (between the flow meter and the supercharger 5, between the supercharger 5 and the throttle body 6, and between the throttle body 6 and the engine intake valve) and the cross-sectional areas A1, A2 and A3 of each section of the pipeline are determined. At the same time, constant parameters such as the molar mass and ideal gas constant of the gas are obtained and set accordingly in the control system, and the volume and cross-sectional area are known.

[0113] According to the calculation method of estimating the volume delay from the flow meter to the intake valve, the collected data is used to calculate the gas passage time t1, t2 and t3 of each section, and the total delay time T is obtained; and during the calculation process, the changes in data are monitored in real time.

[0114] The signal collected by the air flow meter 1 is filtered, and the Kalman filter algorithm is used to set the filter parameters to remove high-frequency noise and interference in the signal. According to the calculated delay time, the filtered signal is delayed to match the delay of the signal with the actual intake process.

[0115] The driver's torque demand signal is obtained through the accelerator pedal position sensor, combined with the engine speed and load signals, and the target intake flow is calculated based on the torque-intake flow mapping relationship pre-stored in the ECU.

[0116] The delayed flow meter signal and the target intake flow are input into the PID controller, and the PID parameters (proportional coefficient, integral time and differential time) are set. The adjustment amount of the injection pulse width is calculated through the PID algorithm, thereby adjusting the actual intake volume to make the actual intake volume close to the target intake flow. During the operation of the engine, the deviation between the actual intake volume and the target intake flow is continuously monitored, and the PID parameters are dynamically adjusted to ensure accurate transient air-fuel ratio control under different working conditions.

[0117] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. An air flow meter signal delay compensation device for an engine transient air-fuel ratio, comprising an air flow meter (1) arranged at the front end of the engine intake, characterized in that: Also includes, The data acquisition device (2) comprises sensors arranged in N sections of the intake pipe from the engine intake front end to the engine intake valve, for acquiring gas parameters in the multiple sections of the intake pipe; N is a positive integer; A delay calculation device (3), connected to the data acquisition device (2), and obtaining a total delay time based on the gas parameters; The delay chip (4) is connected to the delay calculation device (3) and can controllably add the total delay time to the air flow meter (1), so that the air flow meter (1) outputs a delayed flow meter signal.

2. The air flow meter signal delay compensation device according to claim 1, characterized in that: The sensor includes a pressure sensor, a corresponding pressure sensor is arranged in the intake pipe, and the gas parameter includes at least the gas pressure.

3. The air flow meter signal delay compensation device according to claim 2, characterized in that: It also includes a volume database connected to the delay calculation device (3), wherein the volume database stores the volume value of each section of the intake pipe, and the delay calculation device (3) calculates the delay time corresponding to each section of the intake pipe based on the volume value and the gas pressure.

4. The air flow meter signal delay compensation device according to claim 3, characterized in that: The delay calculation device (3) is provided with an adder, which obtains the total delay time based on the addition of the N sections of the intake delay time.

5. The air flow meter signal delay compensation device according to claim 2, characterized in that: The air intake pipe comprises: A first section of an air intake pipe (7) extending from the engine air intake front end to the supercharger (5); A second section of an intake pipe (8) from the supercharger (5) to a throttle body (6) of an engine intake manifold; A third section of the intake pipe (9) extends from the throttle body (6) to the engine intake valve.

6. The air flow meter signal delay compensation device according to claim 5, characterized in that: The air flow meter (1) is provided with a pressure sensor chip to obtain the gas pressure of the first section of the intake pipe (7), and the pressure sensor comprises a first pressure sensor provided in the second section of the intake pipe (8) and a second pressure sensor provided in the third section of the intake pipe (9).

7. The air flow meter signal delay compensation device according to claim 1, characterized in that: The sensor further includes a temperature sensor for detecting the temperature in the intake pipe.

8. The air flow meter signal delay compensation device according to claim 1, characterized in that: It also includes a target intake flow calculation device connected to the air flow meter (1), the target intake flow calculation device receives an external torque signal, and calculates and obtains a target intake flow for adapting the delayed flow meter signal based on a preset torque-intake flow mapping relationship.

9. The air flow meter signal delay compensation device according to claim 1, characterized in that: The air flow meter (1) is also provided with a waveform recorder for recording the flow meter signal of the air flow meter (1), the delay chip (4) is connected to the waveform recorder, and the waveform recorder outputs the delayed flow meter signal based on the superimposed total delay time.

10. The air flow meter signal delay compensation device according to claim 1, characterized in that: The air flow meter (1) is also provided with a signal processing chip, and the signal processing chip can controllably pre-process the delayed flow meter signal.

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