Engine combustion torque estimation method

Abstract

The invention discloses an engine combustion torque estimation method, which comprises the following steps of: when enabling conditions of the engine combustion torque estimation method are met, acquiring operation time of each tooth of an engine crankshaft flywheel disc; determining an evaluation window for estimating the combustion torque of the engine according to the initial crankshaft angle and the tooth number length obtained through calibration, and obtaining an operation time array of each tooth; filtering the operation time array, and outputting a filtering operation time array of each tooth; estimating the engine speed based on the filtering operation time array of each tooth to obtain an engine speed array; estimating a torque difference initial value of each tooth to obtain a torque difference initial value array; filtering the torque difference initial value array, and outputting a filtered torque difference array; and calculating the total torque variation in the evaluation window based on the filtering torque difference array, and judging whether the combustion torque of the engine is abnormal or not. According to the method provided by the invention, the combustion torque of the engine can be estimated so as to identify whether the engine is normal in combustion.

Description

Technical Field

[0001] The present invention relates to the technical field of engine control, and in particular to an engine combustion torque estimation method. Background Art

[0002] Engine combustion produces torque, but if the engine burns abnormally, especially if there is no ignition, the mixture is too lean or too rich, the compression stroke pressure is low, or other reasons, the mixture cannot burn. Therefore, it is necessary to estimate the engine combustion torque to identify whether the engine is burning normally. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an engine combustion torque estimation method in view of the deficiencies in the prior art. The method can estimate the engine combustion torque to identify whether the engine is burning normally.

[0004] To achieve the above object, according to one aspect of the present invention, a method for estimating engine combustion torque is provided, comprising:

[0005] When the enabling condition of the engine combustion torque estimation method is met, the running time of each tooth of the engine crankshaft flywheel is obtained;

[0006] Determine an evaluation window for estimating the engine combustion torque according to the starting crankshaft angle and the tooth length obtained by calibration, and obtain an array of the running time of each tooth in the evaluation window in combination with the running time of each tooth;

[0007] filtering the running time arrays of the respective teeth, and outputting the filtered running time arrays of the respective teeth;

[0008] estimating the engine speed based on the filter operation time array of each tooth to obtain an engine speed array;

[0009] estimating the initial value of the torque difference of each tooth based on the engine speed during the operation of each tooth to obtain an array of initial torque difference values;

[0010] Filtering the torque difference initial value array of each tooth, and outputting a filtered torque difference array of each tooth;

[0011] Calculating the total torque variation within the evaluation window based on the filtered torque difference array of each tooth;

[0012] Whether the engine combustion torque is abnormal is judged according to the total torque change.

[0013] In the above solution, the enabling conditions of the engine combustion torque estimation method include:

[0014] (1) Entering the fire diagnosis area specified in the regulations;

[0015] (2) No request for fuel cut-off;

[0016] (3) The gear position has not changed;

[0017] (4) The clutch is in full engagement;

[0018] (5) Non-uneven road surface;

[0019] (6) The water temperature is within the preset range;

[0020] (7) The throttle opening fluctuation is small during the diagnosis process;

[0021] (8) The engine is in operation.

[0022] In the above scheme, the gear position has not changed means that when the gear position changes, it takes a delay of more than the preset gear change time to activate the engine cylinder injection condition detection method; the clutch is in a fully engaged state means that after the clutch is engaged, it takes a delay of more than the preset clutch time to activate the engine cylinder injection condition detection method; the throttle opening fluctuation is small during the diagnosis process means that the throttle opening fluctuation is small during the diagnosis process means that the difference between the maximum opening and the minimum opening of the throttle within the preset throttle time is less than the preset throttle opening difference.

[0023] In the above scheme, the method for obtaining the running time of each tooth of the engine crankshaft flywheel is:

[0024] The flywheel has 58 teeth plus 2 consecutive missing teeth. The running time of each tooth is t ToothTimes , refers to the time that the engine flywheel needs to go from the current tooth to the next tooth when running, that is, the time between the rising edge of the current tooth and the rising edge of the next tooth is calculated; wherein, the running time of the first tooth before the missing tooth and the two missing teeth are both the average of the running time of the tooth before these three teeth and the running time of the first tooth after the second missing tooth. This is because there are two missing teeth. If the running time of each missing tooth is 0 by default, the running time of the total three teeth (the first tooth before the missing tooth and the two missing teeth) will be 0. However, as an important parameter, the tooth running time will cause misjudgment of the engine combustion torque estimation result, so it needs to be optimized.

[0025] In the above scheme, the starting crankshaft angle phi is obtained by calibration Start and tooth length Cnt ToothArrayLen The method is: phi Start =f 1 (n,rho)+b CatHeat ×f 2 (n,rho), where b Catheat is 1, otherwise bCatheat =0; Considering the catalyst ignition on the starting crankshaft angle phi Start The reason is: during the catalyst ignition process, the engine ignition angle efficiency is too low, resulting in too small engine combustion torque, and it is necessary to increase the evaluation window to evaluate whether the engine combustion is normal;

[0026] f 1 (n,rho) and f 2 (n,rho) is jointly determined by the engine speed and the density of fresh air entering the cylinder. The specific parameters are calibrated on the engine bench. The specific calibration method is: within the evaluation window, in several tests, the absolute value of the average value of the ratio of the difference between the normal and abnormal combustion torques of the engine divided by the normal combustion torque exceeds 20%, and the engine IMEP reaches the maximum value when the engine is in normal combustion; if the absolute value of the average value of the ratio of the difference between the normal and abnormal combustion torques of the engine divided by the normal combustion torque does not exceed 20%, then the calibration is appropriately adjusted to see if it can reach more than 20%. If it still cannot, then these calibrations are no longer adjusted, and the combustion torque estimation method is optimized to improve; after the catalyst is ignited, calibrate f 1 (n,rho) and Cnt ToothArrayLen1 , and then calibrate f during the catalyst light-off process 2 (n,rho) and Cnt ToothArrayLen2 ; The specific calibration method is: the evaluation window and the torque estimation method described later can achieve the most obvious difference between normal and abnormal engine combustion torque, including if the engine combustion is normal and the engine IMEP reaches the maximum value; if it is not obvious, the calibration is appropriately adjusted to see if the difference can be optimized. If not, these calibrations are no longer adjusted, and the improvement is improved by optimizing the combustion torque estimation method;

[0027] When the catalyst is in non-ignition condition or the ignition condition is completed, the tooth length Cnt ToothArrayLen =Cnt ToothArrayLen1 ; In the catalyst ignition condition, the tooth length Cnt ToothArrayLen =Cnt ToothArrayLen2 ;

[0028] The evaluation window for estimating the engine combustion torque is the starting crankshaft angle phi Start The length from the first tooth to the subsequent continuous teeth Cnt ToothArrayLen The operating range of the teeth;

[0029] The starting crankshaft angle phi Start The length from the first tooth to the subsequent continuous teeth Cnt ToothArrayLen +4 teeth running time using array t ToothTimes[0,1,2,...,Cnt ToothArrayLen +3], where the running time array t of each tooth ToothTimes [0,1,2,...,Cnt ToothArrayLen +3] is the running time of the first tooth, and the Cnt ToothArrayLen +3 is the Cnt ToothArrayLen +4 teeth running time.

[0030] In the above solution, the method of filtering the running time array of each tooth and outputting the filtered running time array of each tooth is:

[0031] Calculate the initial value t of the filter time for the running time of each tooth ToothTimesFilterRaw [N] = r 1 ×t ToothTimes [N]+r 2 ×t ToothTimes [N-1]+r 2 ×t ToothTimes [N-2]; where N is the running time array t ToothTimes [0,1,2,...,Cnt ToothArrayLen +3], and when N = 0 or 1, t ToothTimesFilterRaw [0] = t ToothTimes [0], t ToothTimesFilterRaw [1] = t ToothTimes [0], where r 1 , r 2 , r 3 Add up to 1;

[0032] Determine N = 0, 1, 2, ... Cnt ToothArrayLen +3 initial filter time, the final filter running time t ToothTimesFilter [N] = t ToothTimesFilterRaw [N+2], the final filter running time of each tooth constitutes the filter running time array t of each tooth ToothTimesFilter [0,1,2,...,Cnt ToothArrayLen +1].

[0033] The main reason for filtering the running time of each tooth is that the design deviation of the flywheel plate teeth and the accuracy of the crankshaft position sensor will cause more burr signals to appear in the running time of each tooth, which need to be eliminated for engine combustion torque estimation, thereby improving the accuracy of combustion torque estimation. At the same time, after the filtering algorithm, only the running time of the extra two teeth that exceed the evaluation window after filtering needs to be calculated.

[0034] In the above scheme, the method for obtaining the engine speed array is:

[0035] Engine speed Where C1 is the preset value;

[0036] The engine speed during the operation of each tooth constitutes the engine speed array

[0037] n EstRpm [0,1,2,...,Cnt ToothArrayLen +1].

[0038] In the above solution, the method for obtaining the torque difference initial value array is:

[0039] Initial value M of torque difference between each tooth EstTrqErrRaw [N] = C2 × [(n EstRpm [N]) 2 -(n EstRpm [N-1]) 2 ], where C2 is the preset value;

[0040] The initial torque difference values ​​of the teeth constitute the initial torque difference value array

[0041] M EstTrqErrRaw [0,1,2,...,Cnt ToothArrayLen +1].

[0042] In the above solution, the method of filtering the initial value array of the torque difference of each tooth and outputting the filtered torque difference array of each tooth is:

[0043] Calculate the initial value of the torque difference of each tooth

[0044] M EstTrqErrFilter [N] = r 1 ×M EstTrqErrRaw [N]+r 2 ×M EstTrqErrRaw [N-1]+r 2 ×M EstTrqErrRaw [N-2]; where N is the running time array t ToothTimes [0,1,2,...,Cnt ToothArrayLen +3], and when N = 0 or 1, M EstTrqErrFilter [0] = M EstTrqErrRaw [0],M EstTrqErrFilter [1] = M EstTrqErrRaw [0], where r 1 , r 2 , r 3 Add up to 1;

[0045] Determine N = 0, 1, 2, ... Cnt ToothArrayLen After the initial value of the filtering time of +3, the final filtering torque difference M EstTrqErr[N]=M EstTrqErrFilter [N+2], the final filtered torque difference of each tooth constitutes the filtered torque difference array M of each tooth EstTrqErr [0,1,2,...,Cnt ToothArrayLen -1]. The reason for filtering the torque difference initial value array of each tooth and outputting the filtered torque difference array of each tooth is to remove torque signal burrs, thereby improving the accuracy of combustion torque estimation.

[0046] In the above solution, the method for calculating the total torque change in the evaluation window is:

[0047] The filter running time array M of each tooth EstTrqErr [0,1,2,...,Cnt ToothArrayLen -1] are firstly added separately for all non-negative numbers and all negative numbers, and then the two sums are added to obtain the total torque change M TrqDetectDelta The purpose of this is to ensure the accuracy of the accumulation algorithm. If an integer and a negative number are added, some data precision will be lost during the code operation, resulting in a loss of precision in the calculation result.

[0048] In the above scheme, the method for judging whether the engine combustion torque is abnormal according to the total torque change is:

[0049] The total torque change M TrqDetectDelta Filter to obtain the total torque change M after filtering TrqSumMeanNew =(1-r TrqWeightMean )×M TrqSumMean (z)+r TrqWeightMean ×M TrqDetectDelta ; where M TrqSumMean (z) is the total torque change after filtering in the previous sampling period, and its initial default value is 0. The sampling period is 180° crankshaft angle, that is, from the starting crankshaft angle phi Start At the beginning, the sampling calculation is performed again after the crankshaft rotates 180°; r TrqWeightMean is the total torque change filter coefficient, which is a preset value;

[0050] Calculate the initial value S of the torque characteristic value used to evaluate whether the combustion torque is abnormal TrqDetectRaw :S TrqDetectRaw =(1-r TrqWeightVar )×S TrqDetectRaw (z)+r TrqWeightVar ×(M TrqDetectDelta -M TrqSumMeanNew ) 2 ; where S TrqDetectRaw (z) is the initial value of the torque characteristic value in the previous sampling period, and its initial default value is 0;TrqWeightVar is the initial value filter coefficient of the torque characteristic value, and its calculation method is: TrqWeightVar =(1-k TrqWeightVar )×r TrqWeightVar (z)+k TrqWeightVar ×(r TrqWeightGain ×b TrqDetectErr (z)+r TrqWeightInc );where r TrqWeightVar (z) is the initial value filter coefficient of the torque characteristic value in the previous sampling period, and its initial default value is 0.15; k TrqWeightVar is the update coefficient, is the preset value; r TrqWeightGain is the gain coefficient, which is the preset value; r TrqWeightInc is the cumulative coefficient, which is the preset value; b TrqDetectErr (z) is the flag for judging whether the engine combustion torque is abnormal in the previous sampling cycle.

[0051] If abnormal, then b TrqDetectErr (z) takes the value of 1, if there is no abnormality, then b TrqDetectErr The value of (z) is 0;

[0052] The initial value S of the torque characteristic value TrqDetectRaw Filter and obtain the filtered torque characteristic value S TrqDetect :S TrqDetect =(1-r TrqWeightVarFilt )×S TrqDetect (z)+r TrqWeightVar ×S TrqDetectRaw ; where S TrqDetect (z) is the initial value of the torque characteristic value in the previous sampling period, and its initial default value is 0; r TrqWeightVarFilt is the filtering coefficient of the torque characteristic value after filtering, which is a preset value;

[0053] Determine the combustion torque abnormality judgment lower limit value M TrqBoundLower : where k BunndLower is the lower limit deviation coefficient, which is the preset value;

[0054] Calculate the torque deviation M used to determine whether the engine combustion torque is abnormal ErrEst :M ErrEst =M TrqDetectDelta -M TrqBoundLower ;

[0055] Determine whether the engine combustion torque is normal: If M ErrEst <M ErrThresh , then determine whether the engine combustion torque is abnormal flag b TrqDetectErr The value of is set to 1, the engine combustion torque may be abnormal, otherwise the flag bit b is used to determine whether the engine combustion torque is abnormal.TrqDetectErr The value is 0, and the engine combustion torque is normal; the combustion torque deviation limit M ErrThresh is the default value;

[0056] Determine which cylinder of the engine has abnormal combustion: If the engine combustion torque is judged to be abnormal, the flag is b TrqDetectErr If the value of is set to 1, it is read which cylinder is in the power stroke under the corresponding evaluation window, which indicates that the corresponding cylinder may have abnormal combustion;

[0057] The number of combustion abnormalities CNT1 of the corresponding cylinders that may have combustion abnormalities is continuously accumulated, and the number of no combustion abnormalities CNT2 is continuously accumulated, and the default values ​​are both 0; CNT1 and CNT2 are updated at most once each time the enabling condition of the engine combustion torque estimation method is met; each time the enabling condition of the engine combustion torque estimation method is satisfied after being not satisfied, the update of CNT1 and CNT2 is determined again;

[0058] If the reading of CNT1 is greater than the preset value A, and CNT2 is greater than 0 but less than the preset value B, it indicates that the corresponding cylinder has determined that the combustion is abnormal; and the corresponding cylinder combustion abnormality fault is set to occur, and the corresponding cylinder combustion abnormality fault judgment is no longer performed in the subsequent vehicle driving cycle until the diagnostic instrument clears the fault, and the combustion abnormality fault judgment is performed again, and CNT1 and CNT2 are cleared to 0;

[0059] If the reading of CNT1 is greater than 0 but not greater than the preset value A, but CNT2 is 0, and this phenomenon occurs for two consecutive driving cycles, it indicates that the corresponding cylinder is determined to have a combustion abnormality; and the corresponding cylinder combustion abnormality fault is set to occur, and the corresponding cylinder combustion abnormality fault judgment is no longer performed in the subsequent vehicle driving cycle until the diagnostic instrument clears the fault and then performs the combustion abnormality fault judgment, and clears CNT1 and CNT2 to 0;

[0060] If CNT1 is read as 0, but CNT2 is not less than the preset value C, it indicates that the corresponding cylinder has determined that there is no combustion abnormality; and the corresponding cylinder combustion abnormality fault is set not to occur, and the corresponding cylinder combustion abnormality fault judgment is no longer performed in this driving cycle, and the corresponding cylinder combustion abnormality fault judgment is still performed in the subsequent vehicle driving cycle, and CNT1 and CNT2 are cleared to 0;

[0061] In other cases, it indicates that the abnormal combustion fault status of the corresponding cylinder is in a pending state, and it cannot be determined whether a combustion abnormality occurs, and the abnormal combustion fault judgment of the corresponding cylinder is still performed in this driving cycle, and the abnormal combustion fault judgment of the corresponding cylinder is still performed in subsequent vehicle driving cycles; if the abnormal combustion fault status of the corresponding cylinder is in a pending state during the preset number of driving cycles, CNT1 and CNT2 are cleared to 0, otherwise they are not cleared.

[0062] The present invention provides an engine combustion torque estimation method. The method can, under the condition of satisfying the enabling conditions of the engine combustion torque estimation method, continuously estimate the running time of each tooth of the engine, select a reasonable evaluation window for combustion judgment, estimate the rotation speed and torque increment, and estimate the torque increment within the entire evaluation window, and design a reasonable threshold setting method to check whether the engine combustion torque is normal. When the engine combustion torque is abnormal, a flag is output, thereby protecting the engine in time. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Also, throughout the accompanying drawings, the same reference figures are used to represent the same components. In the drawings:

[0064] Figure 1 Schematic diagram of the flow of the engine combustion torque estimation method in an embodiment of the present invention. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0066] It should be understood that the size of the serial numbers of the steps in the 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 the present application.

[0067] Example 1

[0068] The present application provides a method for estimating engine combustion torque. Figure 1 ,include:

[0069] S1, when the enabling condition of the engine combustion torque estimation method is met, the running time of each tooth of the engine crankshaft flywheel is read.

[0070] Specifically, in this embodiment, in order to ensure the accuracy and safety of the engine combustion torque estimation method, the engine combustion torque estimation method of the present invention needs to be performed under enabling conditions to eliminate misjudgment of the engine combustion torque estimation. In the present invention, the enabling condition judgment sampling period is 10ms, and the engine fixed cylinder oil circuit injection action judgment method enabling conditions include:

[0071] (1) Entering the fire diagnosis area specified in the regulations;

[0072] (2) No request for fuel cut-off;

[0073] (3) The gear position has not changed, and after the gear position has changed, a delay of 0.1s is required to activate the engine continuous fuel cut-off verification method;

[0074] (4) The clutch is in full engagement and the engine continuous fuel cut-off verification method can only be activated after a delay of 1 second after the clutch is engaged;

[0075] (5) Non-uneven road surface;

[0076] (6) Water temperature is higher than -6°C;

[0077] (7) The throttle opening fluctuation is small during the diagnosis process, and the difference between the maximum and minimum throttle openings within 0.1 s is less than 15%;

[0078] (8) The engine is in operation.

[0079] After the above conditions are met, the engine combustion torque estimation test can be performed. When the above conditions are not met, the vehicle's operating conditions may cause misjudgment. If the enabling conditions are not met during the diagnosis process, the diagnosis is terminated and the engine combustion torque estimation method is executed again after the next diagnosis condition is met.

[0080] Specifically, in this embodiment, the flywheel has 58 teeth plus 2 consecutive missing teeth, and the running time of each tooth is t ToothTimes , refers to the time it takes for the engine flywheel to go from the current tooth to the next tooth when running, that is, the time between the rising edge of the current tooth and the rising edge of the next tooth is calculated; among them, the running time of the first tooth before the missing tooth and the second missing teeth are both the average of the running time of the tooth before these three teeth and the running time of the first tooth after the second missing tooth.

[0081] S2, determining an evaluation window for estimating the engine combustion torque according to the starting crankshaft angle and the tooth length obtained by calibration, and obtaining an array of the running time of each tooth in the evaluation window in combination with the running time of each tooth.

[0082] Specifically, in this embodiment, the starting crankshaft angle phi is obtained by calibration. Start and tooth length Cnt ToothArrayLen The method is: phi Start =f 1 (n,rho)+b CatHeat ×f 2 (n,rho), where b Catheat is 1, otherwise bCatheat =0; Considering the catalyst ignition on the starting crankshaft angle phi Start The reason is: during the catalyst ignition process, the engine ignition angle efficiency is too low, resulting in too small engine combustion torque, and it is necessary to increase the evaluation window to evaluate whether the engine combustion is normal;

[0083] f 1 (n,rho) and f 2 (n,rho) is jointly determined by the engine speed and the density of the fresh air entering the cylinder. The specific parameters are calibrated on the engine test bench. In the evaluation window, the absolute value of the average value of the ratio of the difference between the normal and abnormal combustion torques of the engine divided by the normal combustion torque in several tests exceeds 20%, and the engine IMEP reaches the maximum value when the engine is normally burned. If the absolute value of the average value of the ratio of the difference between the normal and abnormal combustion torques of the engine divided by the normal combustion torque does not exceed 20%, then the calibration is appropriately adjusted to see if it can reach more than 20%. If it still cannot, then these calibrations are no longer adjusted and the combustion torque estimation method is optimized to improve it. After the catalyst is ignited, calibrate f 1 (n,rho) and Cnt ToothArrayLen , and then calibrate f during the catalyst light-off process 2 (n,rho) and Cnt ToothArrayLen2 ;

[0084] When the catalyst is not in the ignition state or the ignition state is completed, the tooth length Cnt ToothArrayLen =Cnt ToothArrayLen1 ; When the catalyst is ignited, the tooth length Cnt ToothArrayLen =Cnt ToothArrayLen2 ;

[0085] The evaluation window used to estimate the engine combustion torque is the starting crankshaft angle phi Start The length from the first tooth to the subsequent continuous teeth Cnt ToothArrayLen The operating range of the teeth;

[0086] Starting crankshaft angle phi Start The length from the first tooth to the subsequent continuous teeth Cnt ToothArrayLen +4 teeth running time using array t ToothTimes [0,1,2,...,Cnt ToothArrayLen +3], where the running time array t of each tooth ToothTimes [0,1,2,...,Cnt ToothArrayLen +3] is the running time of the first tooth, and the Cnt ToothArrayLen +3 is the Cnt ToothArrayLen +4 teeth running time.

[0087] S3, filtering the running time array of each tooth, and outputting the filtered running time array of each tooth.

[0088] Specifically, in this embodiment, the method of outputting the filter running time array of each tooth is:

[0089] Calculate the initial value t of the filter time for the running time of each tooth ToothTimesFilterRaw [N] = r 1 ×t ToothTimes [N]+r 2 ×t ToothTimes [N-1]+r 2 ×t ToothTimes [N-2]; where N is the running time array t ToothTimes [0,1,2,...,Cnt ToothArrayLen +3], and when N = 0 or 1, t ToothTimesFilterRaw [0] = t ToothTimes [0], t ToothTimesFilterRaw [1] = t ToothTimes [0], where r 1 , r 2 , r 3 Add up to 1, in this example r 1 , r 2 , r 3 They are 0.1708, 0.8821, and -0.0529 respectively;

[0090] Determine N = 0, 1, 2, ... Cnt ToothArrayLen +3 initial filter time, the final filter running time t ToothTimesFilter [N] = t ToothTimesFilterRaw [N+2], the final filter running time of each tooth constitutes the filter running time array t of each tooth ToothTimesFilter [0,1,2,...,Cnt ToothArrayLen +1].

[0091] S4, estimating the initial value of the torque difference of each tooth based on the engine speed during the operation of each tooth, and obtaining an array of the initial value of the torque difference.

[0092] Specifically, in this embodiment, the method for obtaining the engine speed array is:

[0093] Engine speed Wherein C1 is a preset value, in this embodiment C1 = 0.000001min / (r*us);

[0094] The engine speed during the operation of each tooth constitutes the engine speed array n EstRpm[0,1,2,...,Cnt ToothArrayLen +1].

[0095] S5, estimating the initial value of the torque difference of each tooth based on the engine speed during the operation of each tooth, and obtaining an array of the initial value of the torque difference.

[0096] The method to obtain the initial value array of the torque difference is:

[0097] Initial value of torque difference between each tooth Wherein C2 is a preset value, in this embodiment C2 = 3000Nm / (rpm) 2 ;

[0098] The initial values ​​of the torque difference of each tooth constitute the initial value array M of the torque difference EstTrqErrRaw [0,1,2,...,Cnt ToothArrayLen +1].

[0099] S6, filtering the initial value array of the torque difference of each tooth, and outputting the filtered torque difference array of each tooth.

[0100] Specifically, in this embodiment, the method of outputting the filtered torque difference array of each tooth is:

[0101] Calculate the initial value of the filter for the initial value of the torque difference of each tooth

[0102] M EstTrqErrFilter [N] = r 1 ×M EstTrqErrRaw [N]+r 2 ×M EstTrqErrRaw [N-1]+r 2 ×M EstTrqErrRaw [N-2]; where N is the running time array t ToothTimes [0,1,2,...,Cnt ToothArrayLen +3], and when N = 0 or 1, M EstTrqErrFilter [0] = M EstTrqErrRaw [0],M EstTrqErrFilter [1] = M EstTrqErrRaw [0], where r 1 , r 2 , r 3 Add up to 1, in this example r 1 , r 2 , r 3 They are 0.1708, 0.8821, and -0.0529 respectively;

[0103] Determine N = 0, 1, 2, ... Cnt ToothArrayLen After the initial filter time of +3, the final filter torque difference

[0104] MEstTrqErr [N]=M EstTrqErrFilter [N+2], the final filtered torque difference of each tooth constitutes the filtered torque difference array M of each tooth EstTrqErr [0,1,2,...,Cnt ToothArrayLen -1].

[0105] S7, calculating the total torque variation within the evaluation window based on the filtered torque difference array of each tooth.

[0106] Specifically, in this embodiment, the method for calculating the total torque variation within the evaluation window is:

[0107] The filter running time array M of each tooth EstTrqErr [0,1,2,...,Cnt ToothArrayLen -1] are added separately, and then the two sums are added to obtain the total torque change M. TrqDetectDelta .

[0108] S8, judging whether the engine combustion torque is abnormal according to the total torque change.

[0109] Specifically, in the embodiment of the present application, the total torque variation M TrqDetectDelta Filter to obtain the total torque change M after filtering TrqSumMeanNew =(1-r TrqWeightMean )×M TrqSumMean (z)+r TrqWeightMean ×M TrqDetectDelta ; where M TrqSumMean (z) is the total torque change after filtering in the previous sampling period. Its initial default value is 0 and the sampling period is 180°.

[0110] Crankshaft angle, that is, from the starting crankshaft angle phi Start Initially, sampling calculation and updating are performed again after the crankshaft rotates 180°;

[0111] r TrqWeightMean is the total torque change filter coefficient, which is a preset value. In this example, when the catalyst is activated, r TrqWeightMean is 0.05, when the catalyst is not activated TrqWeightMean is 0.1;

[0112] Calculate the initial value S of the torque characteristic value used to evaluate whether the combustion torque is abnormal TrqDetectRaw :S TrqDetectRaw =(1-r TrqWeightVar )×S TrqDetectRaw (z)+r TrqWeightVar ×(M TrqDetectDelta -M TrqSumMeanNew ) 2 ; where STrqDetectRaw (z) is the initial value of the torque characteristic value of the previous sampling period, and its initial default value is 0; TrqWeightVar is the initial value filter coefficient of the torque characteristic value, and its calculation method is: TrqWeightVar =(1-k TrqWeightVar )×r TrqWeightVar (z)+k TrqWeightVar ×(r TrqWeightGain ×b TrqDetectErr (z)+r TrqWeightInc );where r TrqWeightVar (z) is the initial value filter coefficient of the torque characteristic value of the previous sampling period, and its initial default value is 0.15; k TrqWeightVar is the update coefficient, is the preset value, in this example, when the catalyst is activated, k TrqWeightVar is 0.65, when the catalyst is not activated TrqWeightVar is 0.7; r TrqWeightGain is the gain coefficient, which is a preset value. In this example, when the catalyst is activated, r TrqWeightGain is 0.01, when the catalyst is not activated TrqWeightGain is 0.012; r TrqWeightInc is the cumulative coefficient, which is a preset value. In this example, when the catalyst is activated, r TrqWeightInc is 0.17, when the catalyst is not activated TrqWeightInc is 0.1; b TrqDetectErr (z) is the flag for judging whether the engine combustion torque is abnormal in the previous sampling cycle. If abnormal, then b TrqDetectErr (z) takes the value of 1, if there is no abnormality, then b TrqDetectErr The value of (z) is 0;

[0113] The initial value of the torque characteristic value S TrqDetectRaw Filter and obtain the filtered torque characteristic value S TrqDetect :S TrqDetect =(1-r TrqWeightVarFilt )×S TrqDetect (z)+r TrqWeightVar ×S TrqDetectRaw ; where S TrqDetect (z) is the initial value of the torque characteristic value in the previous sampling period, and its initial default value is 0; r TrqWeightVarFilt is the filter coefficient of the torque characteristic value after filtering, is a preset value, in this example, when the catalyst is activated, r TrqWeightVarFilt is 0.3, when the catalyst is not activated TrqWeightVarFilt is 0.15;

[0114] Determine the combustion torque abnormality judgment lower limit value M TrqBoundLower : where k BunndLoweris the lower limit deviation coefficient, is the preset value, in this example, when the catalyst is activated, k BunndLower is 1.8, when the catalyst is not activated BunndLower is 2.3;

[0115] Calculate the torque deviation M used to determine whether the engine combustion torque is abnormal ErrEst :M ErrEst =M TrqDetectDelta -M TrqBoundLower ;

[0116] Determine whether the engine combustion torque is normal: If M ErrEst <M ErrThresh , then determine whether the engine combustion torque is abnormal flag b TrqDetectErr The value of is set to 1, the engine combustion torque may be abnormal, otherwise the flag bit b is used to determine whether the engine combustion torque is abnormal. TrqDetectErr The value is 0, and the engine combustion torque is normal; the combustion torque deviation limit M ErrThresh is a preset value. In this example, when the catalyst is activated, M ErrThresh -0.8Nm, when the catalyst is not activated ErrThresh -1.2Nm;

[0117] Determine which cylinder of the engine has abnormal combustion: If the engine combustion torque is judged to be abnormal, the flag is b TrqDetectErr If the value of is set to 1, it will read which cylinder is in the power stroke under the corresponding evaluation window, indicating that the corresponding cylinder may have abnormal combustion;

[0118] The number of combustion abnormalities CNT1 of the corresponding cylinders that may have combustion abnormalities is continuously accumulated, and the number of times CNT2 that do not have combustion abnormalities is continuously accumulated, and the default values ​​are both 0; CNT1 and CNT2 are updated at most once each time the enabling condition of the engine combustion torque estimation method is met; when the enabling condition of the engine combustion torque estimation method is satisfied after being not satisfied each time, the update of CNT1 and CNT2 is determined again;

[0119] If the reading CNT1 is greater than the preset value A, which is 5 in this example, and CNT2 is greater than 0 but less than the preset value B, which is 2 in this example, it indicates that the corresponding cylinder has a combustion abnormality; and the corresponding cylinder combustion abnormality fault is set to occur, and the corresponding cylinder combustion abnormality fault judgment is no longer performed in the subsequent vehicle driving cycle until the diagnostic instrument clears the fault, and the combustion abnormality fault judgment is performed again, and CNT1 and CNT2 are cleared to 0;

[0120] If the reading of CNT1 is greater than 0 but not greater than the preset value A, but CNT2 is 0, and this phenomenon occurs for two consecutive driving cycles, it indicates that the corresponding cylinder is determined to have a combustion abnormality; and the corresponding cylinder combustion abnormality fault is set to occur, and the corresponding cylinder combustion abnormality fault judgment is no longer performed in the subsequent vehicle driving cycle until the diagnostic instrument clears the fault and then performs the combustion abnormality fault judgment, and clears CNT1 and CNT2 to 0;

[0121] If CNT1 is read as 0, but CNT2 is not less than the preset value C, which is 10 in this example, it indicates that the corresponding cylinder has no combustion abnormality; and it is set that the corresponding cylinder combustion abnormality fault has not occurred, and the corresponding cylinder combustion abnormality fault judgment is no longer performed in this driving cycle, and the corresponding cylinder combustion abnormality fault judgment is still performed in the subsequent vehicle driving cycle, and CNT1 and CNT2 are cleared to 0;

[0122] In other cases, it indicates that the abnormal combustion fault state of the corresponding cylinder is in a pending state, and it cannot be determined whether a combustion abnormality occurs, and the abnormal combustion fault judgment of the corresponding cylinder is still performed in this driving cycle, and the abnormal combustion fault judgment of the corresponding cylinder is still performed in subsequent vehicle driving cycles; if the abnormal combustion fault state of the corresponding cylinder is in a pending state during the preset number of driving cycles (the preset number in this example is 3), CNT1 and CNT2 are cleared to 0, otherwise they are not cleared to zero.

[0123] In summary, the engine combustion torque estimation method provided by the present invention can estimate the engine combustion torque to identify whether the engine combustion is normal.

[0124] It should be pointed out that, according to the needs of implementation, the various steps described in this application can be divided into more steps, or two or more steps or partial operations of the steps can be combined into a new step to achieve the purpose of the present invention.

[0125] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for estimating engine combustion torque, characterized in that: include: When the enabling condition of the engine combustion torque estimation method is met, the running time of each tooth of the engine crankshaft flywheel is obtained; Determine an evaluation window for estimating the engine combustion torque according to the starting crankshaft angle and the tooth length obtained by calibration, and obtain an array of the running time of each tooth in the evaluation window in combination with the running time of each tooth; filtering the running time arrays of the respective teeth, and outputting the filtered running time arrays of the respective teeth; estimating the engine speed based on the filter operation time array of each tooth to obtain an engine speed array; estimating the initial value of the torque difference of each tooth based on the engine speed during the operation of each tooth to obtain an array of initial torque difference values; Filtering the torque difference initial value array of each tooth, and outputting a filtered torque difference array of each tooth; Calculating the total torque variation within the evaluation window based on the filtered torque difference array of each tooth; Whether the engine combustion torque is abnormal is judged according to the total torque change.

2. The engine combustion torque estimation method according to claim 1, characterized in that: The method for obtaining the running time of each tooth of the engine crankshaft flywheel is: The flywheel has 58 teeth plus 2 consecutive missing teeth. The running time of each tooth is t ToothTimes , refers to the time required for the engine flywheel to go from the current tooth to the next tooth when running, that is, the time between the rising edge of the current tooth and the rising edge of the next tooth is calculated; wherein, the running time of the first tooth before the missing tooth and the two missing teeth are both the average of the running time of the tooth before these three teeth and the running time of the first tooth after the second missing tooth.

3. The engine combustion torque estimation method according to claim 1, characterized in that: The starting crankshaft angle phi is obtained by calibration Start and tooth length Cnt ToothArrayLen The method is: phi Start =f1(n,rho)+b CatHeat ×f2(n,rho), where b Catheat is 1, otherwise b Catheat is 0; f1(n,rho) and f2(n,rho) are determined by the engine speed and the density of fresh air entering the cylinder. The specific parameters are calibrated on the engine bench. After the catalyst is ignited, f1(n,rho) and Cnt are calibrated. ToothArrayLen1 Then, f2(n,rho) and Cnt are calibrated during the catalyst light-off process. ToothArrayLen2 ; When the catalyst is in non-ignition condition or the ignition condition is completed, the tooth length Cnt ToothArrayLen =Cnt ToothArrayLen1 ; In the catalyst ignition condition, the tooth length Cnt ToothArrayLen =Cnt ToothArrayLen2 ; The evaluation window for estimating the engine combustion torque is the starting crankshaft angle phi Start The length from the first tooth to the subsequent continuous teeth Cnt ToothArrayLen The operating range of the teeth; The starting crankshaft angle phi Start The length from the first tooth to the subsequent continuous teeth Cnt ToothArrayLen +4 teeth running time using array t ToothTimes [0,1,2,...,Cnt ToothArrayLen +3], where the running time array t of each tooth ToothTimes [0,1,2,...,Cnt ToothArrayLen +3] is the running time of the first tooth, and the Cnt ToothArrayLen +3 is the Cnt ToothArrayLen +4 teeth running time.

4. The engine combustion torque estimation method according to claim 3, characterized in that: The method of filtering the running time array of each tooth and outputting the filtered running time array of each tooth is: Calculate the initial value t of the filter time for the running time of each tooth ToothTimesFilterRaw [N] = r1 × t ToothTimes [N]+r2×t ToothTimes [N-1]+r2×t ToothTimes [N-2]; where N is the running time array t ToothTimes [0,1,2,...,Cnt ToothArrayLen +3], and when N = 0 or 1, t ToothTimesFilterRaw [0] = t ToothTimes [0], t ToothTimesFilterRaw [1] = t ToothTimes [0], where r1, r2, r3 add up to 1; Determine N = 0, 1, 2, ... Cnt ToothArrayLen +3 initial filter time, the final filter running time t ToothTimesFilter [N] = t ToothTimesFilterRaw [N+2], the final filter running time of each tooth constitutes the filter running time array t of each tooth ToothTimesFilter [0,1,2,...,Cnt ToothArrayLen +1].

5. The engine combustion torque estimation method according to claim 4, characterized in that: The method for obtaining the engine speed array is: Engine speed Where C1 is the preset value; The engine speed during the operation of each tooth constitutes the engine speed array n EstRpm [0,1,2,...,Cnt ToothArrayLen +1]。 6. The engine combustion torque estimation method according to claim 5, characterized in that: The method for obtaining the torque difference initial value array is: Initial value of torque difference between each tooth Where C2 is the preset value; The initial torque difference values ​​of the teeth constitute the initial torque difference value array M EstTrqErrRaw [0,1,2,...,Cnt ToothArrayLen +1]。 7. The engine combustion torque estimation method according to claim 6, characterized in that: The method of filtering the initial value array of the torque difference of each tooth and outputting the filtered torque difference array of each tooth is: Calculate the filtered initial value M of the initial value of the torque difference of each tooth EstTrqErrFilter [N] = r1 × M EstTrqErrRaw [N]+r2×M EstTrqErrRaw [N-1]+r2×M EstTrqErrRaw [N-2]; where N is the running time array t ToothTimes [0,1,2,...,Cnt ToothArrayLen +3], and when N = 0 or 1, M EstTrqErrFilter [0] = M EstTrqErrRaw [0],M EstTrqErrFilter [1] = M EstTrqErrRaw [0], where r1, r2, r3 add up to 1; Determine N = 0, 1, 2, ... Cnt ToothArrayLen After the initial value of the filtering time of +3, the final filtering torque difference M EstTrqErr [N]=M EstTrqErrFilter [N+2], the final filtered torque difference of each tooth constitutes the filtered torque difference array M of each tooth EstTrqErr [0,1,2,...,Cnt ToothArrayLen -1].

8. The engine combustion torque estimation method according to claim 7, characterized in that: The method for calculating the total torque variation within the evaluation window is: The filter running time array M of each tooth EstTrqErr [0,1,2,...,Cnt ToothArrayLen -1] are firstly added separately for all non-negative numbers and all negative numbers, and then the two sums are added to obtain the total torque change M TrqDetectDelta .

9. The engine combustion torque estimation method according to claim 8, characterized in that: The method for judging whether the engine combustion torque is abnormal according to the total torque change is: The total torque change M TrqDetectDelta Filter to obtain the total torque change M after filtering TrqSumMeanNew =(1-r TrqWeightMean )×M TrqSumMean (z)+r TrqWeightMean ×M TrqDetectDelta ; where M TrqSumMean (z) is the total torque change after filtering in the previous sampling period, and its initial default value is 0. The sampling period is 180° crankshaft angle, that is, from the starting crankshaft angle phi Start At the beginning, the sampling calculation is performed again after the crankshaft rotates 180°; r TrqWeightMean is the total torque change filter coefficient, which is a preset value; Calculate the initial value S of the torque characteristic value used to evaluate whether the combustion torque is abnormal TrqDetectRaw :S TrqDetectRaw =(1-r TrqWeightVar )×S TrqDetectRaw (z)+r TrqWeightVar ×(M TrqDetectDelta -M TrqSumMeanNew ) 2 ; where S TrqDetectRaw (z) is the initial value of the torque characteristic value in the previous sampling period, and its initial default value is 0; TrqWeightVar is the initial value filter coefficient of the torque characteristic value, and its calculation method is: TrqWeightVar =(1-k TrqWeightVar )×r TrqWeightVar (z)+k TrqWeightVar ×(r TrqWeightGain ×b TrqDetectErr (z)+r TrqWeightInc );where r TrqWeightVar (z) is the initial value filter coefficient of the torque characteristic value in the previous sampling period, and its initial default value is 0.15; k TrqWeightVar is the update coefficient, is the preset value; r TrqWeightGain is the gain coefficient, which is the preset value; r TrqWeightInc is the cumulative coefficient, which is the preset value; b TrqDetectErr (z) is the flag for judging whether the engine combustion torque is abnormal in the previous sampling cycle. If abnormal, then b TrqDetectErr (z) takes the value of 1, if there is no abnormality, then b TrqDetectErr The value of (z) is 0; The initial value S of the torque characteristic value TrqDetectRaw Filter and obtain the filtered torque characteristic value S TrqDetect :S TrqDetect =(1-r TrqWeightVarFilt )×S TrqDetect (z)+r TrqWeightVar ×S TrqDetectRaw ; where S TrqDetect (z) is the initial value of the torque characteristic value in the previous sampling period, and its initial default value is 0; r TrqWeightVarFilt is the filtering coefficient of the torque characteristic value after filtering, which is a preset value; Determine the combustion torque abnormality judgment lower limit value M TrqBoundLower : where k BunndLower is the lower limit deviation coefficient, which is the preset value; Calculate the torque deviation M used to determine whether the engine combustion torque is abnormal ErrEst :M ErrEst =M TrqDetectDelta -M TrqBoundLower ; Determine whether the engine combustion torque is normal: If M ErrEst <M ErrThresh , then determine whether the engine combustion torque is abnormal flag b TrqDetectErr The value of is set to 1, the engine combustion torque may be abnormal, otherwise the flag bit b is used to determine whether the engine combustion torque is abnormal. TrqDetectErr The value is 0, and the engine combustion torque is not abnormal; The combustion torque deviation limit M ErrThresh is the default value; Determine which cylinder of the engine has abnormal combustion: If the engine combustion torque is judged to be abnormal, the flag is b TrqDetectErr If the value of is set to 1, it is read which cylinder is in the power stroke under the corresponding evaluation window, which indicates that the corresponding cylinder may have abnormal combustion; The number of combustion abnormalities CNT1 of the corresponding cylinders that may have combustion abnormalities is continuously accumulated, and the number of no combustion abnormalities CNT2 is continuously accumulated, and the default values ​​thereof are both 0; CNT1 and CNT2 are updated at most once each time the enabling condition of the engine combustion torque estimation method is met; Each time the engine combustion torque estimation method enabling condition is no longer satisfied and then satisfied, the update of CNT1 and CNT2 is determined again; If the reading CNT1 is greater than the preset value A, and CNT2 is greater than 0 but less than the preset value B, it indicates that the corresponding cylinder has determined that the combustion is abnormal; The corresponding cylinder combustion abnormality fault is set to occur, and the corresponding cylinder combustion abnormality fault judgment is no longer performed in the subsequent vehicle driving cycle until the diagnostic instrument clears the fault, and the combustion abnormality fault judgment is performed again, and CNT1 and CNT2 are cleared to 0; If the reading of CNT1 is greater than 0 but not greater than the preset value A, but CNT2 is 0, and this phenomenon occurs for two consecutive driving cycles, it indicates that the corresponding cylinder has determined that combustion abnormality occurs; The corresponding cylinder combustion abnormality fault is set to occur, and the corresponding cylinder combustion abnormality fault judgment is no longer performed in the subsequent vehicle driving cycle until the diagnostic instrument clears the fault and then performs the combustion abnormality fault judgment, and clears CNT1 and CNT2 to 0; If CNT1 is read as 0, but CNT2 is not less than the preset value C, it indicates that there is no combustion abnormality in the corresponding cylinder; It is set that the corresponding cylinder combustion abnormality fault does not occur, and the corresponding cylinder combustion abnormality fault judgment is no longer performed in this driving cycle, and the corresponding cylinder combustion abnormality fault judgment is still performed in the subsequent vehicle driving cycle, and CNT1 and CNT2 are cleared to 0; In other cases, it indicates that the corresponding cylinder combustion abnormality fault state is in an unresolved state, and it cannot be determined whether the combustion abnormality occurs, and the corresponding cylinder combustion abnormality fault judgment is still performed in this driving cycle, and the corresponding cylinder combustion abnormality fault judgment is still performed in subsequent vehicle driving cycles; If the corresponding cylinder combustion abnormality fault status during the preset number of driving cycles is in an unresolved state, CNT1 and CNT2 are cleared to 0, otherwise they are not cleared to 0.

10. The engine combustion torque estimation method according to claim 1, characterized in that: The engine combustion torque estimation method enabling conditions include: (1) Entering the fire diagnosis area specified in the regulations; (2) No request for fuel cut-off; (3) The gear position has not changed; (4) The clutch is in full engagement; (5) Non-uneven road surface; (6) The water temperature is within the preset range; (7) The throttle opening fluctuation is small during the diagnosis process; (8) The engine is in operation.

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