An engine exhaust temperature protection method based on dynamic air volume limitation

Abstract

The present invention discloses an engine exhaust temperature protection method based on dynamic air volume limitation. This method determines the operating condition based on engine speed and intake air density, and determines the maximum ignition efficiency, minimum ignition efficiency, maximum enrichment factor, and minimum enrichment factor under the current operating condition based on pre-calibrated results. The method then sets a first air volume limitation activation flag and a second air volume limitation activation flag under the current operating condition. The method then accumulates the values ​​of the first and second air volume limitation activation flags to obtain a cumulative air volume limitation value, and finally limits the cumulative air volume limitation value to obtain a final air volume limitation value. This method limits engine exhaust temperature without enrichment, thus avoiding the risk of excessive emissions.

Description

Technical Field

[0001] The present invention relates to the field of engine control, and in particular to an engine exhaust temperature protection method based on dynamic gas volume limitation. Background Art

[0002] For gasoline engines, under high torque and power, the intake and oil volumes are large, the final combustion temperature is also high, and the exhaust temperature will be correspondingly high. Long-term operation will cause the exhaust manifold and related components to fatigue due to high temperature or even melt and fail. Therefore, we need to control the exhaust temperature in real time to protect the system. The existing technology generally uses an enrichment strategy to reduce the exhaust temperature, but when running in an enriched state, there is a risk of exceeding the engine emission standard. The Euro VI limit enrichment strategy is proposed. The main purpose of this patent is to not use the enrichment strategy. By reducing the intake and oil volumes, the engine is kept running at the theoretical equivalence ratio to avoid emission risks. At the same time, the air volume limit rate can be dynamically adjusted in real time to switch between fast and slow limits.

[0003] Prior art CN115013217B discloses an engine exhaust temperature protection control method, which reduces engine combustion heat by enriching the air-fuel ratio to protect the exhaust system, thereby protecting the engine and ensuring fuel economy and emission performance.

[0004] The disadvantage of this existing technology is that the extra fuel injected in this solution does not burn, which will cause poor fuel economy and worsening emissions. It does not take into account the poor engine emissions when enriched. As emission regulations become stricter, this strategy will be restricted in use, so this method is not applicable.

[0005] Prior art CN111946475B discloses an exhaust temperature protection method based on air density. This method determines the corresponding air density limit by determining the engine speed and the maximum ignition efficiency for exhaust temperature protection after satisfying the air density protection condition and delaying the response time. Based on this maximum intake air density, intake air density is controlled until the actual engine exhaust temperature falls below the preset exhaust temperature limit.

[0006] The disadvantage of this prior art is that the change in gas density in this solution is calculated by looking up the table based on the change rate, the table value is the bench calibration value, the gas volume limit rate is relatively fixed, and it is impossible to dynamically calculate and adapt to the response speed required by actual conditions. Summary of the Invention

[0007] The object of the present invention is to provide an engine exhaust temperature protection method based on dynamic gas volume limitation to achieve exhaust temperature control under non-enrichment conditions.

[0008] To solve the above technical problems, the present invention provides an engine exhaust temperature protection method based on dynamic air volume limitation, comprising:

[0009] Filtering the intake air density to obtain an intake air density filtering value;

[0010] The maximum ignition efficiency, the minimum ignition efficiency, the maximum enrichment coefficient, and the minimum enrichment coefficient are determined according to the engine speed and the intake air density filter value; the engine speed is obtained through detection;

[0011] The required enrichment of the air-fuel ratio is determined based on the ignition efficiency, minimum ignition efficiency, and maximum ignition efficiency; the ignition efficiency is obtained through measurement;

[0012] Comparing the required enrichment air-fuel ratio with the set air-fuel ratio lower limit value and air-fuel ratio upper limit value, and setting the first gas volume limit activation flag according to the comparison result;

[0013] Determine an ignition efficiency deviation based on the ignition efficiency and the maximum ignition efficiency, compare the ignition efficiency deviation with a set ignition efficiency lower limit value and an ignition efficiency upper limit value, and set a second gas volume limit activation flag according to the comparison result;

[0014] Determine the limited gas volume accumulated value according to the first gas volume limit activation flag and the second gas volume limit activation flag;

[0015] Determine the gas volume limit according to the engine speed;

[0016] The accumulated value of the restricted gas volume is limited according to the gas volume limit value to obtain a final gas volume limit value; the final gas volume limit value is used to limit the gas volume entering the engine cylinder.

[0017] According to the above solution, the method for filtering the intake air density to obtain the intake air density filtered value includes:

[0018] Determine the initial intake density change step size based on the intake density of the previous cycle and the initial intake density value of the current cycle; the initial intake density value is obtained through testing;

[0019] According to the set intake density single-step change limit value, the initial intake density change step length is limited to obtain the intake density change step length;

[0020] Determine the intake density of this cycle based on the intake density change step and the intake density of the previous cycle;

[0021] The intake density of the current cycle is low-pass filtered according to the intake density of the previous cycle to obtain an intake density filtering value.

[0022] According to the above scheme, the method for determining the maximum ignition efficiency, the minimum ignition efficiency, the maximum enrichment factor, and the minimum enrichment factor based on the engine speed and the intake air density filter value is as follows:

[0023] Based on a pre-calibrated table, the maximum ignition efficiency, minimum ignition efficiency, maximum enrichment coefficient, and minimum enrichment coefficient are obtained by linear interpolation according to the engine speed and intake air density filter value;

[0024] The table is calibrated as follows:

[0025] According to the engine speed range and intake air density range of the engine, multiple engine speeds and multiple intake air densities are evenly divided, and different engine speeds and intake air densities form operating points in pairs, thereby generating multiple operating points;

[0026] For each operating point, the following calibration is performed:

[0027] 1) Control the engine ignition angle to the first ignition angle, and obtain the engine ignition efficiency at this time as the minimum ignition efficiency; the first ignition angle is the minimum ignition angle at which the engine can operate normally without enrichment;

[0028] 2) Using stoichiometric combustion, gradually reduce the ignition angle until the exhaust temperature reaches the engine's exhaust temperature mechanical capacity limit. The ignition efficiency corresponding to the ignition angle at this point is taken as the maximum ignition efficiency.

[0029] 3) Control the engine ignition angle to the first ignition angle. If the exhaust temperature reaches the engine exhaust temperature mechanical capacity limit, enrich the fuel until the exhaust temperature does not exceed the engine exhaust temperature mechanical capacity limit. The enrichment coefficient at this time is the minimum enrichment coefficient.

[0030] 4) Control the engine ignition angle to the basic ignition angle. If the exhaust temperature reaches the engine's exhaust temperature mechanical capacity limit, enrich the fuel until the exhaust temperature does not exceed the engine's exhaust temperature mechanical capacity limit. The enrichment factor at this time is the maximum enrichment factor. The basic ignition angle is the ignition angle that can generate maximum torque under the current engine operating point.

[0031] According to the above scheme, the method for determining the required enrichment of the air-fuel ratio based on the ignition efficiency, the minimum ignition efficiency, and the maximum ignition efficiency includes:

[0032] Determine the interpolation coefficient according to the ignition efficiency, the minimum ignition efficiency and the maximum ignition efficiency;

[0033] The required enrichment air-fuel ratio is determined based on the interpolation coefficient, the maximum enrichment coefficient, and the minimum enrichment coefficient.

[0034] According to the above scheme, the method of comparing the required enrichment air-fuel ratio with the set air-fuel ratio lower limit value and air-fuel ratio upper limit value and setting the first gas volume limit activation flag according to the comparison result includes:

[0035] If the required enriched air-fuel ratio is greater than the upper limit of the air-fuel ratio, the first gas volume limit activation flag is set to 1;

[0036] If the required enriched air-fuel ratio is less than the air-fuel ratio lower limit, the first gas volume limitation activation flag is set to 0.

[0037] According to the above solution, the method of comparing the ignition efficiency deviation with the set ignition efficiency lower limit value and ignition efficiency upper limit value and setting the second gas volume limit activation flag according to the comparison result includes:

[0038] If the ignition efficiency deviation is greater than the ignition efficiency upper limit, the second gas volume limit activation flag is set to 1;

[0039] If the ignition efficiency deviation is less than the ignition efficiency lower limit, the second gas volume limit activation flag is set to 0.

[0040] According to the above solution, the method for determining the limited gas volume accumulated value according to the first gas volume limit activation flag and the second gas volume limit activation flag includes:

[0041] If the first gas volume limit activation flag is 1, and the second gas volume limit activation flag is 1 or 0, then the air-fuel ratio limit activation flag is set to 1, and the gas volume increment is determined according to the set first gas volume adjustment rate coefficient and the ignition efficiency deviation. When the air-fuel ratio limit activation flag changes from 0 to 1, the gas volume accumulation value is reset to the current gas volume, and the gas volume accumulation value is determined based on the gas volume increment and the current gas volume accumulation;

[0042] If the first gas limit activation flag is 0 and the second gas limit activation flag is 1, the gas volume increment is set to the preset second gas volume adjustment rate coefficient, and the gas volume cumulative value is determined based on the gas volume cumulative value in the previous cycle and the gas volume increment;

[0043] If the first gas volume limit activation flag is 0, and if the second gas volume limit activation flag is 0, the gas volume increment is set to the preset third gas volume adjustment rate coefficient, and the gas volume cumulative value is determined based on the value of the gas volume cumulative value in the previous cycle and the gas volume increment accumulation.

[0044] According to the above scheme, the method for determining the air volume limit value according to the engine speed is: based on the engine speed-air volume limit value table, the air volume limit value is determined by linear interpolation and table lookup according to the engine speed.

[0045] According to the above scheme, the method of limiting the accumulated value of the restricted gas volume according to the gas volume limit value to obtain the final gas volume limit value includes:

[0046] If the accumulated value of the restricted gas volume is greater than the gas volume limit, the final gas volume limit value is made equal to the gas volume limit;

[0047] If the accumulated value of the restricted gas volume is less than or equal to the gas volume limit, the final gas volume limit value is made equal to the accumulated value of the restricted gas volume.

[0048] The present invention also provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the engine exhaust temperature protection method based on dynamic air volume limitation described above are implemented.

[0049] The beneficial effects of the present invention are: the scheme determines the operating conditions through the engine speed and the intake air density, and determines the values ​​of the first gas volume limit activation flag and the second gas volume limit activation flag under the operating conditions, and then adopts different gas volume limit strategies according to the values ​​of the first gas volume limit activation flag and the second gas volume limit activation flag. The scheme realizes the dynamic adjustment of the gas volume limit during the operation of the vehicle, and does not use the air-fuel ratio enrichment method. It can avoid the risk of exceeding the emission standard while keeping the engine running at the theoretical equivalence ratio, and is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a flow chart of an engine exhaust temperature protection method based on dynamic air volume limitation according to the first embodiment of the present invention. DETAILED DESCRIPTION

[0051] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0052] Example 1:

[0053] This embodiment provides an engine exhaust temperature protection method based on dynamic air volume limitation, which includes the following steps:

[0054] S1. Filter the intake air density to obtain an intake air density filtering value;

[0055] Since the transient values ​​of intake air volume, ignition efficiency and engine speed change dramatically, using transient values ​​for calculation is prone to frequent mis-limiting, so filtering is used;

[0056] Step S1 specifically includes the following steps:

[0057] S101. Determine intake air density;

[0058] According to the intake density Air (z) of the previous cycle and the initial value of the intake density Air0 of this cycle, the initial intake density change step Air is determined. err0 :

[0059] Airerr0 =Air0-Air(z)

[0060] The initial value of intake air density Air0 is obtained through testing;

[0061] According to the set intake air density, the single-step change limit value Air deadband , limit the initial intake air density change step Air err0 , get the intake air density change step Air err :

[0062] If Air err0 Larger than Air deadband , then make Air err =Air deadband ;

[0063] If Air err0 Smaller than -Air deadband , then make Air err =-Air deadband ;

[0064] If Air err0 Greater than -Air deadband And smaller than Air deadband , then make Air err =0;

[0065] Change the step length Air according to the intake air density err , the air density Air (z) of the previous cycle, determine the air density Air of this cycle:

[0066] Air=Air(z)+Air err

[0067] S102, low-pass filter the intake air density to obtain the intake air density filter value Air filter :

[0068] Air filter =Air*k-Air(z)(1-k)

[0069] In the above formula, k is a calibrable constant greater than 0 and less than 1. The larger the value of k, the faster the filtering.

[0070] S2. Determine the maximum ignition efficiency, the minimum ignition efficiency, the maximum enrichment factor, and the minimum enrichment factor based on the engine speed and the intake air density filter value; the engine speed is obtained through detection;

[0071] The maximum ignition efficiency, minimum ignition efficiency, maximum enrichment coefficient, and minimum enrichment coefficient are obtained by linear interpolation table lookup. The table is obtained through calibration, and the calibration process is as follows:

[0072] Since the engine ignition efficiency is directly related to the exhaust temperature, within the conventional ignition angle range, the larger the ignition angle, the higher the ignition efficiency and the lower the exhaust temperature; the richer the mixture, the lower the exhaust temperature. The optimal ignition angle for normal engine operation (generally defined as the ignition angle that can produce the maximum torque at a certain operating point) is defined as the basic ignition angle Sprk Base The inverse of the engine's excess air coefficient is defined as the enrichment coefficient (the enrichment coefficient is 1 for equivalent combustion;

[0073] Based on the engine speed range and intake air density range of the engine, multiple engine speeds and multiple intake air densities are evenly divided (the number of different engine speeds and intake air densities obtained by even division is 10 in this embodiment), and each of the different engine speeds and intake air densities constitutes an operating point, thereby generating multiple operating points (100 in this embodiment);

[0074] Scan all engine operating points on the test bench and perform the following calibration for each operating point:

[0075] Control the engine ignition angle to Sprk Min , the ignition efficiency of the engine at this time is obtained as the minimum ignition efficiency EquivEff Min ;Sprk Min It is the minimum ignition angle for the engine to operate normally without enrichment.

[0076] Use equivalent combustion and gradually reduce the ignition angle until the exhaust temperature reaches the engine exhaust temperature mechanical capacity limit. The ignition efficiency corresponding to the ignition angle at this time is the maximum ignition efficiency EquivEff Start ;

[0077] Control the engine ignition angle to Sprk Min If the exhaust temperature reaches the engine exhaust temperature mechanical capacity limit, enrichment is performed until the exhaust temperature does not exceed the engine exhaust temperature mechanical capacity limit. The enrichment coefficient at this time is the minimum enrichment coefficient Enrich Min ;

[0078] Control the engine ignition angle to Sprk Base If the exhaust temperature reaches the limit of the engine exhaust temperature mechanical capacity, the enrichment is carried out until the exhaust temperature does not exceed the limit of the engine exhaust temperature mechanical capacity. The enrichment coefficient at this time is the maximum enrichment coefficient Enrich Base .

[0079] S3. Determine the required enrichment of the air-fuel ratio based on the ignition efficiency, the minimum ignition efficiency, and the maximum ignition efficiency; the ignition efficiency is obtained by measurement;

[0080] Step S3 specifically includes the following steps:

[0081] S301, according to the ignition efficiency Eff final , minimum ignition efficiency EquivEff Min , Maximum ignition efficiency EquivEff Start Determine the interpolation coefficient K ench :

[0082] K ench =(Eff final -EquivEff Min ) / ( EquivEff Start -EquivEff Min )

[0083] S302, according to the interpolation coefficient K ench , Maximum enrichment coefficient Enrich Base , minimum enrichment coefficient Enrich Min , determine the required enrichment air-fuel ratio AFR ench :

[0084] AFR ench =max[K ench * Enrich Base +(1-K ench )* Enrich Min , 1]

[0085] In the above formula, AFR ench Take K ench * Enrich Base +(1-K ench )* Enrich Min The larger value of 1 and 2 is used to ensure that the output air-fuel ratio is rich.

[0086] S4. Compare the required enrichment air-fuel ratio with the set air-fuel ratio lower limit and air-fuel ratio upper limit, and set the first gas volume limit activation flag according to the comparison result;

[0087] Step S4 specifically includes the following steps:

[0088] If AFR ench >AFR restrict , indicating that the risk of over-temperature is very high at this time, and rapid enrichment is required to prevent the exhaust temperature from exceeding the limit, so the first gas volume limit activation flag is set. afr =1;

[0089] If AFR ench <AFR loosen , enrichment request is not activated, set Flag afr =0;

[0090] AFRrestrict The upper limit of the air-fuel ratio is set, AFR loosen The lower limit value of the air-fuel ratio is set; the purpose of setting the lower limit value of the air-fuel ratio and the upper limit value of the air-fuel ratio is to avoid the first gas volume limit activation flag from frequently switching between the two states, affecting the control.

[0091] S5. Determine an ignition efficiency deviation based on the ignition efficiency and the maximum ignition efficiency, compare the ignition efficiency deviation with a set ignition efficiency lower limit value and an ignition efficiency upper limit value, and set a second gas volume limit activation flag according to the comparison result;

[0092] Step S5 specifically includes the following steps:

[0093] S501, according to the ignition efficiency Eff final and maximum ignition efficiency EquivEff Start Determine the ignition efficiency deviation Eff err :

[0094] Eff err =EquivEff Start -Eff final

[0095] S502: Compare the ignition efficiency deviation with the set ignition efficiency lower limit and ignition efficiency upper limit, and set the second gas volume limit activation flag according to the comparison result;

[0096] If Eff err >Eff restrict , indicating that the current ignition efficiency is low. To control the exhaust temperature, there is a need for enrichment. The second gas volume limit activation flag is set. eff =1;

[0097] If Eff err <Eff loosen , indicating high ignition efficiency, set the second gas limit activation flag Flag eff =0.

[0098] where Eff restrict is the upper limit of the set ignition efficiency, Eff loosen The lower limit value of ignition efficiency is set; the purpose of setting the upper limit value and the lower limit value of ignition efficiency is to avoid the second gas volume limit activation flag from frequently switching between the two states, affecting the control.

[0099] It should be understood that activation of the first gas limit (the first gas limit activation flag is set to 1) indicates that the gas limit demand is larger and faster, and activation of the second gas limit (the second gas limit activation flag is set to 1) indicates that the gas limit demand is smaller and slower.

[0100] S6. Determine the accumulated value of the restricted gas volume according to the first gas volume restriction activation flag and the second gas volume restriction activation flag;

[0101] Step S6 specifically includes the following steps:

[0102] If Flag afr =1, and Flag eff =1 or 0, indicating that there is a high risk of overheating. In order to avoid using enrichment, it is necessary to reduce the fuel volume to cool down and quickly limit the gas volume. In this case, S601 is executed.

[0103] If Flag afr =0, Flag eff =1, at this time, the engine operating area is near the over-temperature area, and the air volume needs to be limited. The enrichment is required, but rapid enrichment is not required. The air volume needs to be limited slowly. At this time, S602 is executed;

[0104] If Flag afr =0, Flag eff =0, at this time, the air-fuel ratio is large, the actual ignition efficiency is low, there is no need to limit the gas volume, and the gas volume needs to be restored; at this time, execute S603;

[0105] S601, set the air-fuel ratio limit activation flag AFR LimFlag =1, set the air volume increment AIR increase = (1 - Eff err ) * K restrict ; Among them, the air-fuel ratio limit activation flag AFR LimFlag The optional value is 0 or 1.

[0106] AFR is triggered when the following two conditions are met at the same time LimFlag Activate AFR LimFlag =1, when any of the following conditions is not met, AFR LimFlag =0.

[0107] Condition 1: Engine exhaust temperature T Exhaust >T ExhEnbl ; where T Exhaust It is the sensor measurement value or directly obtained through other control modules of EMS. ExhEnbl It is a calibratable value representing the engine exhaust temperature tolerance, and is set to 750 in this example;

[0108] Condition 2: The first gas limit activation flag is set afr =1;

[0109] K restrictThe first gas volume adjustment rate coefficient is a positive value. The larger the value, the faster the gas volume decreases. This value needs to be set larger. If Eff err Larger, the air volume increment AIR increase larger;

[0110] When AFR LimFlag When it changes from 0 to 1, that is, AFR LimFlag The previous cycle is 0, the current cycle is 1, reset the flag AFR RestFlag Will be activated once, that is, AFR RestFlag =1, the accumulated value of the limited air volume Air Sum Reset to current air volume AIR Curr , AFR for the next cycle RestFlag It will still be restored to 0 and will not affect the subsequent accumulated values;

[0111] Accumulated calculation to obtain the cumulative value of the limited air volume Air Sum :

[0112] AIR Sum =

[0113] The principle of this step is: as the amount of gas accumulated increases, the accumulated value of air volume is limited. Sum As the air volume decreases, the oil volume also decreases, the exhaust temperature decreases, and the air-fuel ratio AFR needs to be enriched. ench Will decrease, air volume increase AIR increase The absolute value of will also gradually decrease, and finally reach near 0, so that the gas volume limit is always kept at the maximum gas volume state without overheating, and at the same time, there is no need for real enrichment combustion;

[0114] S602, set the air volume increment AIR increase =K restrictRmp ;K restrictrmp The second gas volume adjustment rate coefficient is a negative value. The larger the value, the faster the gas volume decreases. Since the gas volume can be adjusted slowly in this case, it can be adjusted according to a constant rate.

[0115] Make the limited air volume accumulated value Air Sum On AIR Sum (z) is accumulated, AIR Sum (z) is the value of the cumulative limit gas volume in the previous cycle:

[0116] AIR Sum =

[0117] The principle of this step is: limit the gas volume accumulation value to a constant rate, as the gas volume decreases, the oil volume also decreases synchronously, the ignition efficiency deviation Eff errIt will decrease until the second gas limit activation flag is set. eff =0, ignition efficiency deviation Eff err Finally, it reaches near 0, so that the gas volume limit is always kept at the maximum gas volume state without overheating, and at the same time, there is no need for real enrichment combustion;

[0118] S603, set the air volume increment AIR increase= K loosenRmp ; where K loosenRmp The third gas volume adjustment coefficient is a positive value. The larger the value, the faster the gas volume increases.

[0119] Make the limited air volume accumulated value Air Sum On AIR Sum (z) is accumulated based on:

[0120] AIR Sum =

[0121] The principle of this step is: limit the gas volume accumulation value to a constant rate, as the gas volume increases, the oil volume also increases synchronously, the ignition efficiency deviation Eff err It will increase and eventually become unlimited.

[0122] In the above three different situations, different gas volume increments are used to switch between fast and slow rate limits and releases.

[0123] S7. Determine the air volume limit value according to the engine speed;

[0124]

[0125] In the table, Engine Speed is the engine speed in rpm / min, Air lim It is the gas volume limit, the unit is mg / l.

[0126] S8. Limiting the accumulated value of the restricted air volume according to the air volume limit value to obtain a final air volume limit value; the final air volume limit value is used to limit the air volume entering the engine cylinder;

[0127] When AIR Sum >Air lim When the final air volume limit value AIR final =Air lim ;

[0128] When AIR Sum ≤Air lim When the final air volume limit value AIR final =AIR Sum .

[0129] Example 2:

[0130] This embodiment provides a computer device, which may be a smartphone, tablet computer, laptop computer, desktop computer, rack-mounted server, blade server, tower server, or cabinet-mounted server (including a standalone server or a server cluster consisting of multiple servers), capable of executing programs. The computer device of this embodiment includes at least, but is not limited to, a memory and a processor that are interconnected via a system bus.

[0131] In this embodiment, the memory (i.e., readable storage medium) includes flash memory, hard disks, multimedia cards, card-type memories (e.g., SD or DX memories), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), and programmable read-only memory (PROM). The memory may also be an external storage device of the computer device, such as a plug-in hard disk, a SmartMedia Card (SMC), a Secure Digital (SD) card, a flash memory card, etc. Of course, the memory may also include both the internal storage unit of the computer device and its external storage devices. In this embodiment, the memory is typically used to store the operating system and various application software installed on the computer device, such as the program code of the engine exhaust temperature protection method based on dynamic air volume limitation in Example 1. Furthermore, the memory may also be used to temporarily store various data that has been output or is about to be output.

[0132] In some embodiments, the processor can be a central processing unit (CPU), a controller, a microcontroller, a microprocessor, or other data processing chip. Such a processor is typically used to control the overall operation of a computer device. In this embodiment, the processor is used to execute program code stored in a memory or process data, such as executing program code for an engine exhaust temperature protection method based on dynamic air volume limitation.

[0133] Example 3:

[0134] The present application also provides a computer-readable storage medium, such as a flash memory, a hard disk, a multimedia card, a card-type memory (e.g., SD or DX memory), a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic storage device, a disk, an optical disk, a server, an app store, etc., storing a computer program that implements corresponding functions when executed by a processor. The computer-readable storage medium of this embodiment is used to store program code for an engine exhaust temperature protection method based on dynamic air volume limitation, and when executed by a processor, implements the engine exhaust temperature protection method based on dynamic air volume limitation of Example 1.

[0135] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, or two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0136] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0137] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An engine exhaust temperature protection method based on dynamic air volume limitation, characterized in that: include: Filtering the intake air density to obtain an intake air density filtering value; The maximum ignition efficiency, the minimum ignition efficiency, the maximum enrichment coefficient, and the minimum enrichment coefficient are determined according to the engine speed and the intake air density filter value; the engine speed is obtained through detection; The required enrichment of the air-fuel ratio is determined based on the ignition efficiency, minimum ignition efficiency, and maximum ignition efficiency; the ignition efficiency is obtained through measurement; Comparing the required enrichment air-fuel ratio with the set air-fuel ratio lower limit value and air-fuel ratio upper limit value, and setting the first gas volume limit activation flag according to the comparison result; Determine an ignition efficiency deviation based on the ignition efficiency and the maximum ignition efficiency, compare the ignition efficiency deviation with a set ignition efficiency lower limit value and an ignition efficiency upper limit value, and set a second gas volume limit activation flag according to the comparison result; Determine the limited gas volume accumulated value according to the first gas volume limit activation flag and the second gas volume limit activation flag; Determine the gas volume limit according to the engine speed; The accumulated value of the restricted gas volume is limited according to the gas volume limit value to obtain a final gas volume limit value; the final gas volume limit value is used to limit the gas volume entering the engine cylinder.

2. The engine exhaust temperature protection method based on dynamic air volume limitation according to claim 1, characterized in that: The method for filtering the intake air density to obtain the intake air density filtering value includes: Determine the initial intake density change step size based on the intake density of the previous cycle and the initial intake density value of the current cycle; the initial intake density value is obtained through testing; According to the set intake density single-step change limit value, the initial intake density change step length is limited to obtain the intake density change step length; Determine the intake density of this cycle based on the intake density change step and the intake density of the previous cycle; The intake density of the current cycle is low-pass filtered according to the intake density of the previous cycle to obtain an intake density filtering value.

3. The engine exhaust temperature protection method based on dynamic air volume limitation according to claim 1, characterized in that: The method for determining the maximum ignition efficiency, the minimum ignition efficiency, the maximum enrichment factor, and the minimum enrichment factor based on the engine speed and the intake air density filter value is as follows: Based on a pre-calibrated table, the maximum ignition efficiency, minimum ignition efficiency, maximum enrichment coefficient, and minimum enrichment coefficient are obtained by linear interpolation according to the engine speed and intake air density filter value; The table is calibrated as follows: According to the engine speed range and intake air density range of the engine, multiple engine speeds and multiple intake air densities are evenly divided, and different engine speeds and intake air densities form operating points in pairs, thereby generating multiple operating points; For each operating point, the following calibration is performed: 1) Control the engine ignition angle to the first ignition angle, and obtain the engine ignition efficiency at this time as the minimum ignition efficiency; the first ignition angle is the minimum ignition angle at which the engine can operate normally without enrichment; 2) Using stoichiometric combustion, gradually reduce the ignition angle until the exhaust temperature reaches the engine's exhaust temperature mechanical capacity limit. The ignition efficiency corresponding to the ignition angle at this point is taken as the maximum ignition efficiency. 3) Control the engine ignition angle to the first ignition angle. If the exhaust temperature reaches the engine exhaust temperature mechanical capacity limit, enrich the fuel until the exhaust temperature does not exceed the engine exhaust temperature mechanical capacity limit. The enrichment coefficient at this time is the minimum enrichment coefficient. 4) Control the engine ignition angle to the basic ignition angle. If the exhaust temperature reaches the engine's exhaust temperature mechanical capacity limit, enrich the fuel until the exhaust temperature does not exceed the engine's exhaust temperature mechanical capacity limit. The enrichment factor at this time is the maximum enrichment factor. The basic ignition angle is the ignition angle that can generate maximum torque under the current engine operating point.

4. The engine exhaust temperature protection method based on dynamic air volume limitation according to claim 1, characterized in that: The method for determining the required enrichment of the air-fuel ratio based on the ignition efficiency, the minimum ignition efficiency, and the maximum ignition efficiency includes: Determine the interpolation coefficient according to the ignition efficiency, the minimum ignition efficiency and the maximum ignition efficiency; The required enrichment air-fuel ratio is determined based on the interpolation coefficient, the maximum enrichment coefficient, and the minimum enrichment coefficient.

5. The engine exhaust temperature protection method based on dynamic air volume limitation according to claim 1, characterized in that: The method of comparing the required enrichment air-fuel ratio with the set air-fuel ratio lower limit value and air-fuel ratio upper limit value, and setting the first gas volume limit activation flag according to the comparison result includes: If the required enriched air-fuel ratio is greater than the upper limit of the air-fuel ratio, the first gas volume limit activation flag is set to 1; If the required enriched air-fuel ratio is less than the air-fuel ratio lower limit, the first gas volume limitation activation flag is set to 0.

6. The engine exhaust temperature protection method based on dynamic air volume limitation according to claim 5, characterized in that: The method of comparing the ignition efficiency deviation with the set ignition efficiency lower limit value and ignition efficiency upper limit value, and setting the second gas volume limit activation flag according to the comparison result includes: If the ignition efficiency deviation is greater than the ignition efficiency upper limit, the second gas volume limit activation flag is set to 1; If the ignition efficiency deviation is less than the ignition efficiency lower limit, the second gas volume limit activation flag is set to 0.

7. The engine exhaust temperature protection method based on dynamic air volume limitation according to claim 6, characterized in that: The method for determining the limited gas volume accumulated value according to the first gas volume limit activation flag and the second gas volume limit activation flag includes: If the first gas volume limit activation flag is 1, and the second gas volume limit activation flag is 1 or 0, then the air-fuel ratio limit activation flag is set to 1, and the gas volume increment is determined according to the set first gas volume adjustment rate coefficient and the ignition efficiency deviation. When the air-fuel ratio limit activation flag changes from 0 to 1, the gas volume accumulation value is reset to the current gas volume, and the gas volume accumulation value is determined based on the gas volume increment and the current gas volume accumulation; If the first gas limit activation flag is 0 and the second gas limit activation flag is 1, the gas volume increment is set to the preset second gas volume adjustment rate coefficient, and the gas volume cumulative value is determined based on the gas volume cumulative value in the previous cycle and the gas volume increment; If the first gas volume limit activation flag is 0, and if the second gas volume limit activation flag is 0, the gas volume increment is set to the preset third gas volume adjustment rate coefficient, and the gas volume cumulative value is determined based on the value of the gas volume cumulative value in the previous cycle and the gas volume increment accumulation.

8. The engine exhaust temperature protection method based on dynamic air volume limitation according to claim 1, characterized in that: The method for determining the air volume limit value according to the engine speed is: based on the engine speed-air volume limit value table, the air volume limit value is determined by linear interpolation and table lookup according to the engine speed.

9. The engine exhaust temperature protection method based on dynamic air volume limitation according to claim 1, characterized in that: The method of limiting the accumulated value of the restricted gas volume according to the gas volume limit value to obtain the final gas volume limit value includes: If the accumulated value of the restricted gas volume is greater than the gas volume limit, the final gas volume limit value is made equal to the gas volume limit; If the accumulated value of the restricted gas volume is less than or equal to the gas volume limit, the final gas volume limit value is made equal to the accumulated value of the restricted gas volume.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the engine exhaust temperature protection method based on dynamic air volume limitation according to any one of claims 1 to 9 are implemented.

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