Air-fuel ratio control method and device, vehicle, storage medium and program product

Abstract

The invention relates to the technical field of engine control, in particular to an air-fuel ratio control method and device, a vehicle, a storage medium and a program product.The method comprises the steps that the current working condition of an engine is detected; the change rate of the air-fuel ratio is generated according to the current working condition; and according to the change rate of the air-fuel ratio, the air-fuel ratio delay control time for controlling the exhaust temperature within the target safety range is determined, and air-fuel ratio delay control is carried out based on the delay control time. According to the embodiment of the invention, the delay control time of the air-fuel ratio can be determined according to the change rate of the air-fuel ratio when the exhaust temperature is within the target safety range, so that the delay control of the air-fuel ratio is carried out, the engine can obtain the optimal combustion efficiency under different working conditions, the fuel consumption is reduced, the power output is improved, and the energy consumption is reduced. The dynamic property of the engine is protected from loss, and the service life is prolonged.

Description

Technical Field

[0001] The present application relates to the field of engine control technology, and in particular to an air-fuel ratio control method, device, vehicle, storage medium and program product. Background Art

[0002] At present, the most mainstream core technology route to achieve fuel saving and reduce carbon emissions is to replace large-displacement naturally aspirated engines with exhaust gas turbocharged direct injection engines. However, since the thermal load of turbocharged direct injection engines is large under high-speed and high-load conditions, the fuel mixture needs to be appropriately enriched to reduce the exhaust temperature. At this time, a large amount of unburned fuel accumulates at the front end of the exhaust. If the engine speed and load are reduced in a short period of time, the air-fuel ratio increases, and the unburned fuel in the three-way catalytic converter burns rapidly, the exhaust temperature rises rapidly, and causes serious damage to the engine exhaust system. Therefore, the temperature of the exhaust system needs to be controlled.

[0003] In the related technology, the target air-fuel ratio enrichment coefficient can be constrained after the delayed response time, and then the output air-fuel ratio enrichment coefficient can be obtained, and the output air-fuel ratio enrichment coefficient can be compensated to the air-fuel ratio request control, that is, the air-fuel ratio can be optimized until the actual exhaust temperature is lower than the preset limit of the exhaust temperature; the theoretical combustion heat release value can also be calculated according to the engine intake volume, the target air-fuel ratio, and the hydrogen injection volume, and then the theoretical exhaust temperature can be calculated, and the target air-fuel ratio can be corrected when the preset correction conditions are met between the actual exhaust temperature and the theoretical exhaust temperature.

[0004] However, in the related art, when the engine speed and load suddenly decrease, the air-fuel ratio may be adjusted too rich, affecting the engine economy, which urgently needs to be improved. Summary of the invention

[0005] The present application provides an air-fuel ratio control method, device, vehicle, storage medium and program product to solve the problem in the related art that under the condition of a sudden decrease in engine speed and load, the air-fuel ratio may be adjusted too rich, affecting the economy of the engine.

[0006] The first aspect of the present application provides an air-fuel ratio control method for a vehicle, the method comprising the following steps: detecting a current operating condition of an engine; generating a rate of change of the air-fuel ratio according to the current operating condition; determining a delay control time for controlling the air-fuel ratio to be within a target safety range according to the rate of change of the air-fuel ratio, so as to perform air-fuel ratio delay control based on the delay control time.

[0007] Through the above technical scheme, the change rate of the air-fuel ratio can be generated in real time according to the current operating conditions of the engine, and the delay control time of the air-fuel ratio can be determined when the exhaust temperature is within the target safety range, and then the air-fuel ratio delay control can be performed. By accurately controlling the air-fuel ratio, it can be ensured that the engine can obtain the best combustion efficiency under different operating conditions, thereby reducing fuel consumption and improving power output. The exhaust temperature can be indirectly controlled by controlling the air-fuel ratio, and it can be ensured that the engine operates within a safe temperature range, thereby extending its service life.

[0008] Optionally, in one embodiment of the present application, the delay control time of the air-fuel ratio for controlling the exhaust temperature within a target safety range is determined based on the rate of change of the air-fuel ratio, including: when the rate of change is less than a preset threshold, determining that the exhaust temperature increase trend meets a preset safety condition, and determining that the delay control time is zero; when the rate of change is greater than or equal to a preset threshold, calculating the exhaust temperature increase rate based on the engine's intake volume, and determining the delay control time based on the exhaust temperature increase rate.

[0009] Through the above technical scheme, the rising trend of the exhaust temperature can be determined in real time according to the relationship between the change rate and a certain threshold value, and then different delay control time strategies can be determined, thereby ensuring the safety and immediacy of engine operation. The change rate of the air-fuel ratio is used as the basis for judgment, and the delay control time is calculated using the engine's intake volume. It can be dynamically adjusted according to actual needs under different working conditions, thereby improving the flexibility and adaptability of the system and realizing the intelligence and adaptability of the delay control time control.

[0010] Optionally, in one embodiment of the present application, the rate of change of the air-fuel ratio generated according to the current operating condition includes: determining an ideal target air-fuel ratio corresponding to the current operating condition according to the engine speed and intake volume; calculating the difference between the ideal target air-fuel ratio and the actual air-fuel ratio, and determining the rate of change according to the difference.

[0011] Through the above technical scheme, the ideal target air-fuel ratio corresponding to the current operating conditions can be determined according to the engine speed and intake volume, and then the difference between the ideal target air-fuel ratio and the actual air-fuel ratio can be calculated, thereby obtaining the rate of change of the air-fuel ratio. By adjusting the air-fuel ratio in real time, it can be ensured that the engine can provide sufficient power and responsiveness at different speeds and loads, thereby maintaining the engine in the best operating state.

[0012] Optionally, in one embodiment of the present application, determining the delay control time according to the exhaust temperature rise rate includes: determining the deviation limit of the air-fuel ratio; determining the variation coefficient of the air-fuel ratio according to the intake air volume and the deviation limit, and obtaining the actual target air-fuel ratio according to the ideal target air-fuel ratio, the actual air-fuel ratio and the variation coefficient to determine the delay control time.

[0013] Through the above technical scheme, the deviation limit of the air-fuel ratio can be determined first, then the change coefficient of the air-fuel ratio can be determined, and then the delay control time can be determined. By setting the deviation limit, it can be determined that the difference between the ideal target air-fuel ratio and the actual air-fuel ratio is within a controllable range, and the actual target air-fuel ratio can be adjusted quickly to avoid over-adjustment or under-adjustment, so that the engine can adapt to changes in operating conditions more quickly.

[0014] The second aspect of the present application provides an air-fuel ratio control device for a vehicle, the device comprising: a detection module for detecting the current operating condition of the engine; a generation module for generating the rate of change of the air-fuel ratio according to the current operating condition; a control module for determining the delay control time of the air-fuel ratio for controlling the exhaust temperature within a target safety range according to the rate of change of the air-fuel ratio, so as to perform air-fuel ratio delay control based on the delay control time.

[0015] Through the above technical scheme, the change rate of the air-fuel ratio can be generated in real time according to the current operating conditions of the engine, and the delay control time of the air-fuel ratio can be determined when the exhaust temperature is within the target safety range, and then the air-fuel ratio delay control can be performed. By accurately controlling the air-fuel ratio, it can be ensured that the engine can obtain the best combustion efficiency under different operating conditions, thereby reducing fuel consumption and improving power output. The exhaust temperature can be indirectly controlled by controlling the air-fuel ratio, and it can be ensured that the engine operates within a safe temperature range, thereby extending its service life.

[0016] Optionally, in one embodiment of the present application, the control module includes: a first determination unit, used to determine that the exhaust temperature increase trend meets a preset safety condition when the change rate is less than a preset threshold, and determine that the delay control time is zero; a second determination unit, used to calculate the exhaust temperature increase rate based on the engine's intake volume when the change rate is greater than or equal to a preset threshold, and determine the delay control time based on the exhaust temperature increase rate.

[0017] Through the above technical scheme, the rising trend of the exhaust temperature can be determined in real time according to the relationship between the change rate and a certain threshold value, and then different delay control time strategies can be determined, thereby ensuring the safety and immediacy of engine operation. The change rate of the air-fuel ratio is used as the basis for judgment, and the delay control time is calculated using the engine's intake volume. It can be dynamically adjusted according to actual needs under different working conditions, thereby improving the flexibility and adaptability of the system and realizing the intelligence and adaptability of the delay control time control.

[0018] Optionally, in one embodiment of the present application, the generation module includes: a generation unit, used to determine the ideal target air-fuel ratio corresponding to the current operating condition based on the engine speed and intake volume; a calculation unit, used to calculate the difference between the ideal target air-fuel ratio and the actual air-fuel ratio, and determine the change rate based on the difference.

[0019] Through the above technical scheme, the ideal target air-fuel ratio corresponding to the current operating conditions can be determined according to the engine speed and intake volume, and then the difference between the ideal target air-fuel ratio and the actual air-fuel ratio can be calculated, thereby obtaining the rate of change of the air-fuel ratio. By adjusting the air-fuel ratio in real time, it can be ensured that the engine can provide sufficient power and responsiveness at different speeds and loads, thereby maintaining the engine in the best operating state.

[0020] Optionally, in one embodiment of the present application, the second determination unit includes: a first determination subunit, used to determine the deviation limit of the air-fuel ratio; a second determination subunit, used to determine the variation coefficient of the air-fuel ratio according to the intake amount and the deviation limit, and obtain the actual target air-fuel ratio according to the ideal target air-fuel ratio, the actual air-fuel ratio and the variation coefficient to determine the delay control time.

[0021] Through the above technical scheme, the deviation limit of the air-fuel ratio can be determined first, then the change coefficient of the air-fuel ratio can be determined, and then the delay control time can be determined. By setting the deviation limit, it can be determined that the difference between the ideal target air-fuel ratio and the actual air-fuel ratio is within a controllable range, and the actual target air-fuel ratio can be adjusted quickly to avoid over-adjustment or under-adjustment, so that the engine can adapt to changes in operating conditions more quickly.

[0022] The third aspect of the present application provides a vehicle, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the air-fuel ratio control method of the vehicle as described in the above embodiment.

[0023] The fourth aspect of the present application provides a computer-readable storage medium, which stores a computer program, and when the program is executed by a processor, it implements the above-mentioned vehicle air-fuel ratio control method.

[0024] The fifth aspect of the present application provides a computer program product, including a computer program, which, when executed, implements the above-mentioned vehicle air-fuel ratio control method.

[0025] The embodiment of the present application can generate the rate of change of the air-fuel ratio in real time according to the current working condition of the engine, and determine the delay control time of the air-fuel ratio when the exhaust temperature is within the target safety range, and then perform air-fuel ratio delay control. By accurately controlling the air-fuel ratio, it can ensure that the engine can obtain the best combustion efficiency under different working conditions, thereby reducing fuel consumption and improving power output. By controlling the air-fuel ratio, the exhaust temperature is indirectly controlled to ensure that the engine operates within a safe temperature range, extend its service life, and improve the economy of the engine. In this way, the technical problem in the related technology that under the working condition of sudden reduction of engine speed and load, the air-fuel ratio may be adjusted too rich, affecting the economy of the engine, etc. is solved.

[0026] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0028] Figure 1 A schematic diagram of the structure of an engine control system provided according to an embodiment of the present application;

[0029] Figure 2 A flow chart of an air-fuel ratio control method for a vehicle provided according to an embodiment of the present application;

[0030] Figure 3 A flow chart of determining the delay control time according to the exhaust temperature increase rate provided according to an embodiment of the present application;

[0031] Figure 4 It is a block diagram of an air-fuel ratio control device for a vehicle provided according to an embodiment of the present application;

[0032] Figure 5 It is a schematic diagram of the structure of a vehicle provided according to an embodiment of the present application.

[0033] Reference numerals:

[0034] Among them, 101-intake flow meter, 102-injector, 103-three-way catalytic converter, 104-oxygen sensor, 105-temperature sensor, 106-ECU (Electronic Control Unit), 107-air filter; 40-vehicle air-fuel ratio control device; 401-detection module, 402-generation module, 403-control module; 501-memory, 502-processor, 503-communication interface. DETAILED DESCRIPTION

[0035] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0036] The following describes the air-fuel ratio control method, device, vehicle, storage medium and program product of the embodiment of the present application with reference to the accompanying drawings. In view of the problem mentioned in the above background technology that the air-fuel ratio may be adjusted too rich under the working condition of the engine's speed and load suddenly reduced, affecting the economy of the engine, the present application provides an air-fuel ratio control method for a vehicle, in which the change rate of the air-fuel ratio can be generated in real time according to the current working condition of the engine, and the delay control time of the air-fuel ratio can be determined when the exhaust temperature belongs to the target safety range, and then the air-fuel ratio delay control is performed. By accurately controlling the air-fuel ratio, it can be ensured that the engine can obtain the best combustion efficiency under different working conditions, thereby reducing fuel consumption and improving power output, and indirectly controlling the exhaust temperature by controlling the air-fuel ratio, ensuring that the engine operates within a safe temperature range, extending its service life, and providing the economy of the engine. Thus, the technical problems such as the air-fuel ratio adjustment being too rich and affecting the economy of the engine under the working condition of the engine's speed and load suddenly reduced in the related technology are solved.

[0037] Before introducing the air-fuel ratio control method of a vehicle proposed in the embodiment of the present application, the overall system structure of the engine involved in the embodiment of the present application is first explained.

[0038] Specifically, Figure 1 The figure is a schematic diagram of the structure of an engine control system provided according to one embodiment of the present application.

[0039] like Figure 1 As shown, 101 is an intake air flow meter, 102 is a fuel injector, 103 is a three-way catalytic converter, 104 is an oxygen sensor, 105 is a temperature sensor, 106 is an ECU, and 107 is an air filter.

[0040] The intake flow meter 101 of the embodiment of the present application is installed between the air filter 107 and the intake pipe, and is connected to the ECU 106 through a control signal line. The function of the intake flow meter 101 is to collect the actual intake air volume in the intake manifold and feed it back to the ECU 106 to calculate the injection amount under the current working conditions.

[0041] The injector 102 is installed in each cylinder through the fuel rail and connected to the ECU 106 through a control signal line. The function of the injector 102 is to calculate the current air-fuel ratio and the injection pulse width under the rail pressure according to the intake volume actually measured by the intake flow meter 101, and then control the injection volume.

[0042] The three-way catalytic converter 103 is installed at the rear end of the turbocharger of the exhaust system and is an important external purification device. Under conditions with large intake volume, a large amount of unburned mixture enters the catalytic reactor, causing the exhaust temperature to be too high, affecting the efficiency of the catalytic converter, and even causing damage in severe cases.

[0043] The oxygen sensor 104 is installed at the front end of the three-way catalytic converter 103 and is connected to the ECU 106 through a control signal line. It is mainly used to monitor the oxygen content in the exhaust gas after engine combustion and convert the oxygen content into a voltage signal to the ECU 106 for calculating the injection amount under the current working conditions.

[0044] The temperature sensor 105 is installed at the center of the three-way catalytic converter 103 to measure the exhaust temperature at the catalyst center. The calibration engineer adjusts the air-fuel ratio based on this to protect the three-way catalytic converter 103 from being damaged by high temperature.

[0045] ECU106 is connected to intake air flow meter 101, fuel injector 102, oxygen sensor 104 and other sensors and actuators of the engine through control signal lines. The function of ECU106 is to receive measurement signals from engine sensors, calculate and output control signals to actuators through software data, and ensure stable operation of the engine.

[0046] Furthermore, during operation of the engine of the embodiment of the present application, fresh air is filtered by the air filter 107 and flows through the intake flow meter 101. The intake flow meter 101 measures the amount of fresh air entering the engine, thereby calculating and controlling the injection amount of the injector 102 through the ECU 106. The mixed gas enters the cylinder and burns to do work, then is discarded and flows into the exhaust manifold. After being purified by the three-way catalytic converter 103, it is discharged into the atmosphere. The oxygen sensor 104 measures the oxygen content in the exhaust system, and calculates the engine air-fuel ratio at this time through the ECU 106 to correct the injection amount.

[0047] It is understandable that the current common control strategy of the engine is to determine the target air-fuel ratio λ under the current working conditions based on the engine speed and intake volume. This target value is optimized by the calibration engineer during the bench and vehicle calibration, with the catalyst temperature not exceeding the design value of the three-way catalytic converter material failure as the benchmark. The theoretical injection amount is calculated based on this air-fuel ratio target value and the intake volume, and the injection pulse width is adjusted in combination with the injection pressure. The fuel is mixed with the fresh air entering the cylinder and burned to perform work, and enters the exhaust manifold through the exhaust valve. At this time, the oxygen sensor calculates the actual air-fuel ratio based on the oxygen content in the exhaust gas, compares it with the target air-fuel ratio, calculates the air-fuel ratio correction coefficient, and corrects the injection amount accordingly to make the actual air-fuel ratio approach the target air-fuel ratio.

[0048] In most low-load conditions, the engine will control the air-fuel ratio to be near 1, at which time the economy and power are in a relatively good state. However, when the engine is running under high-load conditions, due to the increase in exhaust temperature, if the air-fuel ratio is always kept at 1, the temperature in the three-way catalytic converter will also increase, the catalytic efficiency will decrease, and in severe cases, the catalyst will burn out. Therefore, under high load, the target air-fuel ratio needs to be appropriately reduced, that is, the injection amount needs to be increased, in order to reduce the combustion temperature in the cylinder, and then reduce the exhaust temperature to protect the three-way catalytic converter. When the engine suddenly drops from high speed and high load to low speed and low load, there is a large amount of unburned fuel in the three-way catalytic converter. At this time, the air-fuel ratio suddenly increases, resulting in a large amount of afterburning. The temperature of the three-way catalytic converter rises rapidly in a short period of time, which can easily cause the catalyst to burn out.

[0049] Therefore, the embodiment of the present application can adjust the air-fuel ratio change rate according to the difference between the engine target and the actual air-fuel ratio and the intake volume. For example, when the difference between the engine target and the actual air-fuel ratio is small, if the intake volume is also small, the air-fuel ratio change rate can be relatively large, and even no delay control is required; while when the difference between the engine target and the actual air-fuel ratio is large, and the intake volume is also large, the air-fuel ratio change rate needs to be slowed down so that the exhaust temperature does not exceed the maximum limit. The adjustment of the change rate is mainly achieved through a fixed interval time ΔT, and the air-fuel ratio change rate coefficient is multiplied by ΔT to obtain the actual change in the air-fuel ratio. After multiple iterations, the actual air-fuel ratio gradually approaches the theoretical target air-fuel ratio.

[0050] Specifically, Figure 2 The present invention is a flowchart of a method for controlling the air-fuel ratio of a vehicle provided according to an embodiment of the present application.

[0051] like Figure 2 As shown, the air-fuel ratio control method of the vehicle includes the following steps:

[0052] In step S201, the current operating condition of the engine is detected.

[0053] It can be understood that the current operating condition of the engine in the embodiment of the present application may include but is not limited to a low load condition, a medium load condition, a high load condition, etc., and the present application does not impose any specific limitation.

[0054] Among them, the low load condition can be understood as a small throttle opening, generally within 25%. Under this condition, the amount of mixed gas entering the cylinder is small, the conditions for gasoline atomization and evaporation are relatively poor, and the residual exhaust gas has a strong dilution effect on the mixed gas. Therefore, the supplied mixed gas is relatively rich to ensure the stability of the engine under low load conditions.

[0055] Medium load conditions can be understood as the throttle opening is within the range of 25% to 85%, and the engine works under this condition most of the time. At this time, an economical concentration of mixed gas is supplied to ensure that the engine has good fuel economy. As the load increases, the throttle gradually opens wider and the mixed gas gradually becomes thinner.

[0056] Under high load conditions, in order to protect the engine exhaust system, the air-fuel ratio needs to be enriched to reduce the exhaust temperature. At this time, a large amount of unburned fuel will accumulate in the three-way catalytic converter and the particulate filter. If the load is suddenly reduced at this time, such as releasing the accelerator pedal, going down a long slope, or cutting off the fuel, a large amount of fresh air will enter the exhaust system, causing the unburned fuel to burn quickly and the exhaust temperature to rise rapidly, especially for the horizontally placed exhaust system structure.

[0057] In the actual implementation process, in order to maintain good economy of the engine, the embodiment of the present application needs to detect the current operating condition of the engine so that the exhaust temperature will not be too high under different operating conditions to cause engine damage.

[0058] In step S202, the rate of change of the air-fuel ratio is generated according to the current operating conditions.

[0059] It is understandable that the embodiments of the present application can obtain different air-fuel ratio conversion rates according to different engine operating conditions. The air-fuel ratio can be understood as the mass ratio of air to fuel in the engine combustion chamber, which directly affects the combustion efficiency, power, economy and emission performance of the engine.

[0060] In the embodiment of the present application, the air-fuel ratio change rate generated under different working conditions may include:

[0061] Under low load conditions, as the load increases, the rate of change of the air-fuel ratio gradually increases to adapt to changes in engine load and fuel economy requirements.

[0062] Under medium load conditions, as the load further increases, the air-fuel ratio may be adjusted slightly, but the overall rate of change is relatively smooth to maintain engine stability and economy.

[0063] Under high load conditions, the air-fuel ratio changes at a greater rate to quickly respond to changes in engine load and power requirements.

[0064] Therefore, the embodiment of the present application can generate the rate of change of the air-fuel ratio according to the current operating conditions.

[0065] For example, in the embodiment of the present application, during the operation of the engine, the ECU can collect the engine intake volume and the voltage value fed back by the oxygen sensor in real time, adjust the injection pulse width through the oil circuit model calculation, and generate the air-fuel ratio change rate through closed-loop control, so as to make the actual air-fuel ratio λ equal to the ideal target air-fuel ratio λ des .

[0066] In step S203, the delay control time of the air-fuel ratio for controlling the exhaust temperature within the target safety range is determined according to the change rate of the air-fuel ratio, so as to perform air-fuel ratio delay control based on the delay control time.

[0067] It can be understood that when the rate of change of the air-fuel ratio changes in the embodiment of the present application, the exhaust temperature will also change accordingly. Therefore, the embodiment of the present application can determine an appropriate delay control time according to the rate of change of the air-fuel ratio to achieve precise control of the air-fuel ratio, thereby controlling the exhaust temperature within the target safety range.

[0068] As a possible implementation method, the embodiment of the present application can determine the delayed control time of the air-fuel ratio according to the change rate of the air-fuel ratio and the exhaust temperature within the target safety range, thereby realizing the delayed control of the air-fuel ratio. Among them, the target safety range can be set by technicians in this field according to actual conditions, and this application does not make specific restrictions.

[0069] Optionally, in one embodiment of the present application, the rate of change of the air-fuel ratio is generated according to the current operating conditions, including: determining the ideal target air-fuel ratio corresponding to the current operating conditions according to the engine speed and intake volume; calculating the difference between the ideal target air-fuel ratio and the actual air-fuel ratio, and determining the rate of change according to the difference.

[0070] It can be understood that in the engine control system of the present application embodiment, it is an important step to determine the ideal target air-fuel ratio corresponding to the current working condition according to the engine speed and intake volume. The ideal target air-fuel ratio is the optimal air-fuel ratio of the engine under steady-state conditions, generally 14.7:1, which is the best mass ratio of air and gasoline during complete combustion. It can be set by technicians in this field according to actual conditions, and this application does not make specific restrictions. However, in actual applications, due to various factors, such as engine load, speed, temperature, emission requirements, etc., the ideal target air-fuel ratio will be adjusted according to the current working condition. At this time, the embodiment of the present application can use a table lookup method to find the ideal target air-fuel ratio corresponding to the current working condition. The ideal target air-fuel ratio of the embodiment of the present application is a control table in the ECU, the horizontal coordinate of which can be the speed Speed ​​(unit: r / min), the vertical coordinate can be the charging coefficient Rl_mess (unit: %), and the output control parameter is the ideal target air-fuel ratio, specifically as shown in Table 1, wherein Table 1 is a control table of the ideal target air-fuel ratio provided according to an embodiment of the present application.

[0071] Table 1

[0072] Speed / Rl_mess 1000 2000 3000 4000 5000 6000 20 1 1 1 1 1 1 40 1 1 1 1 1 0.95 60 1 1 1 1 0.95 0.9 80 1 1 1 0.95 0.9 0.85 100 1 0.95 0.9 0.85 0.8 0.75 120 0.95 0.9 0.85 0.8 0.75 0.7

[0073] Furthermore, the actual air-fuel ratio of the embodiment of the present application can be measured by an oxygen sensor installed in the exhaust system, which can be specifically set by technicians in this field according to actual conditions, and this application does not impose any specific limitations.

[0074] In some embodiments, the embodiments of the present application can first determine the ideal target air-fuel ratio corresponding to the current operating conditions based on the engine speed and intake volume, and then calculate the difference between the ideal target air-fuel ratio and the actual air-fuel ratio, and determine the change rate based on the difference.

[0075] Optionally, in one embodiment of the present application, the delay control time for controlling the air-fuel ratio to keep the exhaust temperature within a target safety range is determined based on the rate of change of the air-fuel ratio, including: when the rate of change is less than a preset threshold, determining that the exhaust temperature increase trend meets a preset safety condition, and determining the delay control time to be zero; when the rate of change is greater than or equal to a preset threshold, calculating the exhaust temperature increase rate based on the engine's intake volume, and determining the delay control time based on the exhaust temperature increase rate.

[0076] It can be understood by those skilled in the art that, through the above analysis, the delay control time of the embodiment of the present application depends on the change rate and the exhaust temperature. Therefore, the embodiment of the present application can determine the delay control time by transforming between the two.

[0077] Specifically, in some embodiments, when the rate of change is less than a certain threshold, it can be determined that the exhaust temperature rise trend meets a certain safety condition. At this time, the embodiment of the present application can determine that the delay control time is zero. Among them, the certain threshold and the certain safety condition can be set by technicians in this field according to actual conditions, and this application does not make specific restrictions.

[0078] In some embodiments, when the rate of change is greater than or equal to a certain threshold, the exhaust temperature rise rate can be calculated based on the engine's intake volume, and the delay control time can be determined.

[0079] For example, the embodiment of the present application can calculate the rate of change of the air-fuel ratio within a certain interval in real time, and adjust the delay control time of the actual air-fuel ratio to control the rate of increase of the exhaust temperature. Further, in the embodiment of the present application, when the rate of change is small, the exhaust temperature increase trend judged at this time is low, and certain safety conditions are met, and no delay control is performed. When the rate of change is large, the rate of increase of the exhaust temperature can be inferred based on the intake volume, and the air-fuel ratio can be delayed to control the exhaust temperature.

[0080] Optionally, in one embodiment of the present application, the delay control time is determined according to the exhaust temperature increase rate, including: determining the deviation limit of the air-fuel ratio; determining the variation coefficient of the air-fuel ratio according to the intake amount and the deviation limit, and obtaining the actual target air-fuel ratio according to the ideal target air-fuel ratio, the actual air-fuel ratio and the variation coefficient to determine the delay control time.

[0081] As a possible implementation method, the embodiment of the present application can first determine the deviation limit of the air-fuel ratio, and then determine the variation coefficient of the air-fuel ratio, and use the ideal target air-fuel ratio, the actual air-fuel ratio and the variation coefficient to obtain the actual target air-fuel ratio, and finally determine the delay control time.

[0082] Specifically, the embodiment of the present application can set the first deviation limit of the air-fuel ratio to λ lim1 This value can be set by technicians in this field according to actual conditions and is not specifically limited in this application.

[0083] It can be understood that, in the embodiment of the present application, when the difference is greater than 0 and less than λ lim1 When the first variation coefficient L1 of the air-fuel ratio under the current working condition can be determined according to the actual engine intake volume Air_in (unit: kg / h), it is a control curve about the intake volume in the ECU, which can be described in the form of a table, such as shown in Table 2, wherein Table 2 is a control table of the first variation coefficient of the air-fuel ratio provided according to an embodiment of the present application.

[0084] Table 2

[0085] Air_in 100 200 400 600 800 1000 1200 1400 1600 L1 0 0 0 0.1 0.15 0.2 0.25 0.3 0.4

[0086] Further, when the difference is greater than or equal to the first deviation limit, the embodiment of the present application may set the second deviation limit of the air-fuel ratio difference to λ lim2 This value can be set by technicians in this field according to actual conditions and is not specifically limited in this application.

[0087] It can be understood that, in the embodiment of the present application, the difference is greater than or equal to λ lim1 Less than λ lim2 When the second variation coefficient L2 of the air-fuel ratio under the current working condition can be determined according to Air_in, it is a control curve about the intake amount in the ECU, which can be described in the form of a table, such as shown in Table 3, wherein Table 3 is a control table of the second variation coefficient of the air-fuel ratio provided according to another embodiment of the present application.

[0088] Table 3

[0089] Air_in 100 200 400 600 800 1000 1200 1400 1600 L2 0 0.05 0.15 0.25 0.4 0.55 0.7 0.75 0.8

[0090] Further, when the difference is greater than or equal to the second deviation limit, the third deviation limit of the air-fuel ratio difference can be set to λ lim3 This value can be set by technicians in this field according to actual conditions and is not specifically limited in this application.

[0091] It can be understood that, in the embodiment of the present application, when the difference is greater than or equal to λ lim2 When the third variation coefficient L3 of the air-fuel ratio under the current working condition can be determined according to Air_in, it is a control curve about the intake amount in the ECU, which can be described in the form of a table, such as shown in Table 4, wherein Table 4 is a control table of the third variation coefficient of the air-fuel ratio provided according to another embodiment of the present application.

[0092] Table 4

[0093] Air_in 100 200 400 600 800 1000 1200 1400 1600 L3 0.1 0.15 0.25 0.35 0.45 0.6 0.75 0.85 0.9

[0094] For example, Figure 3 As shown, an embodiment of the present application is a flow chart for determining the delay control time according to the exhaust temperature increase rate.

[0095] Step S301: During engine operation, the actual air-fuel ratio λ is made equal to the actual target air-fuel ratio λ through closed-loop control des .

[0096] Step S302: Determine the ideal target air-fuel ratio under the current operating conditions.

[0097] Among them, the embodiment of the present application first sets the calculation interval time ΔT, for example, ΔT=0.2s, which can be specifically set by technicians in this field according to actual conditions, and this application does not make any specific restrictions.

[0098] Furthermore, in the embodiment of the present application, after ΔT, the ideal target air-fuel ratio λ1 under the current working condition is determined according to the engine speed and the intake air volume, and its value can be queried using Table 1.

[0099] Step S303: Calculate the difference Δλ between the ideal target air-fuel ratio λ1 and the actual air-fuel ratio λ.

[0100] Among them, the calculation formula of the difference Δλ in the embodiment of the present application can be but is not limited to: Δλ=λ1-λ.

[0101] Step S304: determine whether the difference is less than or equal to 0.

[0102] In this embodiment of the present application, when the difference is less than or equal to 0, step S305 is executed; otherwise, step S306 is executed.

[0103] Step S305: Assign the ideal target air-fuel ratio to the actual target air-fuel ratio.

[0104] It can be understood that, in the embodiment of the present application, when Δλ≤0, λ des =λ1.

[0105] Step S306: Determine whether the difference is less than the first deviation limit.

[0106] In this embodiment of the present application, when the difference is less than the first deviation limit, step S307 is executed; otherwise, step S308 is executed.

[0107] Step S307: The actual target air-fuel ratio is equal to the difference between the ideal target air-fuel ratio and the product of the above difference and the first variation coefficient.

[0108] It can be understood that in the embodiment of the present application, when 0<Δλ<λ lim1 When des =λ1-Δλ*L1, where λ can be lim1 =0.1, which can be specifically set by technicians in this field according to actual conditions, and this application does not make any specific limitation.

[0109] In addition, the value of L1 in the embodiment of the present application can be found in Table 2, and the present application does not impose any specific limitation.

[0110] Step S308: Determine whether the difference is less than the second deviation limit.

[0111] In this embodiment of the present application, when the difference is less than the second deviation limit, step S309 is executed; otherwise, step S310 is executed.

[0112] Step S309: The actual target air-fuel ratio is equal to the difference between the ideal target air-fuel ratio and the product of the above difference and the second variation coefficient.

[0113] It can be understood that, in the embodiment of the present application, lim1 <Δλ<λ lim2 When des =λ1-Δλ*L2, wherein the embodiment of the present application can lim2 =0.2, which can be specifically set by technicians in this field according to actual conditions, and this application does not make any specific limitation.

[0114] In addition, the value of L2 in the embodiment of the present application can be queried through Table 3, and the present application does not make any specific limitations.

[0115] Step S310: The actual target air-fuel ratio is equal to the difference between the ideal target air-fuel ratio and the product of the above difference and the third variation coefficient.

[0116] It can be understood that in the embodiment of the present application, when Δλ>λ lim2 When des =λ1-Δλ*L3, wherein the value of L3 can be found in Table 4, and this application does not make any specific limitation.

[0117] Step S311: Determine the delay control time based on the actual target air-fuel ratio and perform air-fuel ratio delay control.

[0118] According to the vehicle air-fuel ratio control method proposed in the embodiment of the present application, the rate of change of the air-fuel ratio can be generated in real time according to the current working condition of the engine, and the delay control time of the air-fuel ratio can be determined when the exhaust temperature is within the target safety range, and then the air-fuel ratio delay control can be performed. By accurately controlling the air-fuel ratio, it can be ensured that the engine can obtain the best combustion efficiency under different working conditions, thereby reducing fuel consumption and improving power output. The exhaust temperature can be indirectly controlled by controlling the air-fuel ratio to ensure that the engine operates within a safe temperature range, extend its service life, and improve the economy of the engine. In this way, the technical problem in the related art that under the working condition of a sudden decrease in engine speed and load, the air-fuel ratio may be adjusted too rich, affecting the economy of the engine, etc.

[0119] Next, an air-fuel ratio control device for a vehicle proposed in accordance with an embodiment of the present application will be described with reference to the accompanying drawings.

[0120] Figure 4 It is a block diagram of an air-fuel ratio control device for a vehicle provided according to an embodiment of the present application.

[0121] like Figure 4 As shown, the air-fuel ratio control device 40 of the vehicle includes: a detection module 401 , a generation module 402 and a control module 403 .

[0122] The detection module 401 is used to detect the current working condition of the engine.

[0123] The generating module 402 is used to generate the rate of change of the air-fuel ratio according to the current operating conditions.

[0124] The control module 403 is used to determine the delay control time of the air-fuel ratio for controlling the exhaust temperature within the target safety range according to the change rate of the air-fuel ratio, so as to perform air-fuel ratio delay control based on the delay control time.

[0125] Optionally, in an embodiment of the present application, the control module 403 includes: a first determining unit and a second determining unit.

[0126] The first determination unit is used to determine that the exhaust temperature increase trend meets a preset safety condition and determine that the delay control time is zero when the change rate is less than a preset threshold.

[0127] The second determination unit is used to calculate the exhaust temperature increase rate according to the intake volume of the engine when the change rate is greater than or equal to a preset threshold, and determine the delay control time according to the exhaust temperature increase rate.

[0128] Optionally, in one embodiment of the present application, the generation module 402 includes: a generation unit and a calculation unit.

[0129] The generating unit is used to determine the ideal target air-fuel ratio corresponding to the current working condition according to the engine speed and intake air volume.

[0130] The calculation unit is used to calculate the difference between the ideal target air-fuel ratio and the actual air-fuel ratio, and determine the change rate according to the difference.

[0131] Optionally, in one embodiment of the present application, the second determining unit includes: a first determining subunit and a second determining subunit.

[0132] Wherein, the first determination subunit is used to determine the deviation limit of the air-fuel ratio.

[0133] The second determination subunit is used to determine the variation coefficient of the air-fuel ratio according to the intake air amount and the deviation limit, and obtain the actual target air-fuel ratio according to the ideal target air-fuel ratio, the actual air-fuel ratio and the variation coefficient to determine the delay control time.

[0134] It should be noted that the above explanation of the embodiment of the vehicle air-fuel ratio control method is also applicable to the vehicle air-fuel ratio control device of this embodiment, and will not be repeated here.

[0135] According to the air-fuel ratio control device of the vehicle proposed in the embodiment of the present application, the rate of change of the air-fuel ratio can be generated in real time according to the current working condition of the engine, and the delay control time of the air-fuel ratio can be determined when the exhaust temperature is within the target safety range, and then the air-fuel ratio delay control can be performed. By accurately controlling the air-fuel ratio, it can be ensured that the engine can obtain the best combustion efficiency under different working conditions, thereby reducing fuel consumption and improving power output. The exhaust temperature can be indirectly controlled by controlling the air-fuel ratio to ensure that the engine operates within a safe temperature range, extend its service life, and improve the economy of the engine. In this way, the technical problem in the related art that under the working condition of a sudden decrease in engine speed and load, the air-fuel ratio may be adjusted too rich, affecting the economy of the engine, etc.

[0136] Figure 5 This is a schematic diagram of the structure of a vehicle provided according to an embodiment of the present application. The vehicle may include:

[0137] A memory 501 , a processor 502 , and a computer program stored in the memory 501 and executable on the processor 502 .

[0138] When the processor 502 executes the program, the air-fuel ratio control method of the vehicle provided in the above embodiment is implemented.

[0139] Furthermore, the vehicle also includes:

[0140] The communication interface 503 is used for communication between the memory 501 and the processor 502 .

[0141] The memory 501 is used to store computer programs that can be executed on the processor 502 .

[0142] The memory 501 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0143] If the memory 501, the processor 502 and the communication interface 503 are implemented independently, the communication interface 503, the memory 501 and the processor 502 can be connected to each other through a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 5Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0144] Optionally, in a specific implementation, if the memory 501, the processor 502 and the communication interface 503 are integrated on a chip, the memory 501, the processor 502 and the communication interface 503 can communicate with each other through an internal interface.

[0145] The processor 502 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0146] An embodiment of the present application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned vehicle air-fuel ratio control method.

[0147] An embodiment of the present application also provides a computer program product, including a computer program, which implements the above-mentioned vehicle air-fuel ratio control method when executed.

[0148] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0149] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0150] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0151] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or N wirings (electronic devices), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways as necessary and then storing it in a computer memory.

[0152] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented by hardware, as in another embodiment, it can be implemented by any one or a combination of multiple of the following technologies known in the art: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0153] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0154] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0155] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for controlling the air-fuel ratio of a vehicle, characterized in that: The following steps are involved: Detect the current operating condition of the engine; generating a rate of change of the air-fuel ratio according to the current operating condition; The delay control time of the air-fuel ratio for controlling the exhaust temperature within a target safety range is determined according to the change rate of the air-fuel ratio, so as to perform air-fuel ratio delay control based on the delay control time.

2. The method according to claim 1, characterized in that The method of determining the delay control time of the air-fuel ratio to control the exhaust temperature within the target safety range according to the change rate of the air-fuel ratio includes: When the change rate is less than a preset threshold, it is determined that the exhaust temperature increase trend meets a preset safety condition, and the delay control time is determined to be zero; When the change rate is greater than or equal to a preset threshold, the exhaust temperature increase rate is calculated according to the intake air volume of the engine, and the delay control time is determined according to the exhaust temperature increase rate.

3. The method according to claim 2, characterized in that Generating the change rate of the air-fuel ratio according to the current operating condition includes: Determining an ideal target air-fuel ratio corresponding to the current operating condition according to the engine speed and intake air volume; The difference between the ideal target air-fuel ratio and the actual air-fuel ratio is calculated, and the change rate is determined according to the difference.

4. The method according to claim 3, characterized in that The step of determining the delay control time according to the exhaust temperature increase rate includes: determining a deviation limit of the air-fuel ratio; The variation coefficient of the air-fuel ratio is determined according to the intake air amount and the deviation limit, and the actual target air-fuel ratio is obtained according to the ideal target air-fuel ratio, the actual air-fuel ratio and the variation coefficient to determine the delay control time.

5. An air-fuel ratio control device for a vehicle, characterized in that: include: A detection module, used to detect the current working condition of the engine; A generating module, used for generating a change rate of the air-fuel ratio according to the current operating condition; A control module is used to determine a delay control time of the air-fuel ratio for controlling the exhaust temperature within a target safety range according to a change rate of the air-fuel ratio, so as to perform air-fuel ratio delay control based on the delay control time.

6. The device according to claim 5, characterized in that The control module comprises: A first determining unit, configured to determine, when the change rate is less than a preset threshold value, that the exhaust temperature increase trend satisfies a preset safety condition, and to determine that the delay control time is zero; The second determination unit is used to calculate the exhaust temperature increase rate according to the intake volume of the engine when the change rate is greater than or equal to a preset threshold, and determine the delay control time according to the exhaust temperature increase rate.

7. The device according to claim 6, characterized in that The generating module comprises: A generating unit, configured to determine an ideal target air-fuel ratio corresponding to the current operating condition according to the rotation speed and intake air volume of the engine; The calculation unit is used to calculate the difference between the ideal target air-fuel ratio and the actual air-fuel ratio, and determine the change rate according to the difference.

8. A vehicle, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the air-fuel ratio control method for a vehicle as described in any one of claims 1 to 4.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the air-fuel ratio control method of a vehicle as described in any one of claims 1 to 4.

10. A computer program product, characterized in that It comprises a computer program, which, when executed, is used to implement the air-fuel ratio control method of the vehicle as claimed in any one of claims 1 to 4.

Images