A method for identifying dynamic fuel cut-off of an engine

Abstract

The present invention discloses a method for identifying dynamic fuel cutoffs in an engine, comprising: when enabling conditions for the dynamic fuel cutoff verification method are met, obtaining the operating time of each cylinder of the engine at a certain crankshaft operating angle and calculating the average operating time; determining the operating time update coefficient when conditions for activating the operating time update optimization process are met; determining the value of a flag; determining the final operating time based on the flag value and the operating time update coefficient, calculating the final operating time average and a characteristic coefficient; determining the value of the initial flag of a fixed cylinder based on the characteristic coefficient and a self-learning correction coefficient; determining the value of the final flag of the fixed cylinder based on the value of the initial flag, and determining whether a true fuel cutoff has occurred in the fixed cylinder. The method provided by the present invention can detect whether a fixed cylinder fuel cutoff has occurred in the engine, thereby reminding the driver to perform timely maintenance and inspection to protect the engine.

Description

Technical Field

[0001] The present invention relates to the technical field of engine control, and in particular to a method for identifying dynamic fuel cut-off of an engine. Background Art

[0002] Failure to promptly identify an engine fuel shutoff can negatively impact engine performance, emissions, and economy. Therefore, it's crucial to monitor whether a specific cylinder fuel shutoff has occurred, alerting the driver to prompt repairs and inspections to protect the engine. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an engine dynamic fuel cut-off identification method to address the deficiencies of the existing technology. The method can detect whether the engine has a fixed cylinder fuel cut-off, thereby reminding the driver to perform timely maintenance and inspection to protect the engine.

[0004] To achieve the above objectives, according to one aspect of the present invention, a method for identifying dynamic fuel cut-off of an engine is provided, comprising:

[0005] When the enabling conditions of the engine dynamic fuel cut-off verification method are met, the operating time of each cylinder of the engine in a range of crankshaft operating angles is obtained, and the average operating time of each cylinder of the engine in a plurality of consecutive sampling periods is calculated;

[0006] When the activation conditions for the run time update optimization process are met, a fuel cutoff is requested for all cylinders of the engine. At this time, the engine is in operation and the vehicle is in coasting. An evaluation region is divided according to the engine speed, and a run time update coefficient is determined based on the evaluation region.

[0007] Determining whether the activation condition for the run time update optimization process and the evaluation area have changed, and determining a value of a run time update optimization counter and an initial value of the run time update coefficient according to the run time update coefficient and the run time average value;

[0008] Determine the value of the flag bit according to the value of the runtime update optimization counter; determine the updated runtime update coefficient according to the value of the flag bit, the initial value of the runtime update coefficient and the runtime update coefficient;

[0009] Determine a final running time according to the value of the flag bit, the updated running time update coefficient, and the running time;

[0010] Calculating an average of the final operating time of each cylinder of the engine within a plurality of consecutive sampling periods based on the final operating time to obtain a characteristic coefficient; determining a value of an initial flag of a fixed cylinder based on the characteristic coefficient and a self-learning correction coefficient;

[0011] The value of the final flag of the fixed cylinder is determined according to the value of the initial flag, and whether the fixed cylinder is truly fuel-off is determined according to the value of the final flag.

[0012] In the above solution, the enabling conditions of the engine dynamic fuel cut-off verification method include:

[0013] (1) Enter the fire diagnosis area specified in the regulations;

[0014] (2) No fuel cut-off request;

[0015] (3) The gear position has not changed;

[0016] (4) The clutch is in full engagement;

[0017] (5) Non-uneven road surface;

[0018] (6) The water temperature is within the preset range;

[0019] (7) The throttle opening fluctuation is small during the diagnosis process;

[0020] (8) The engine is in running state.

[0021] 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 gear change preset 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 clutch preset 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 throttle preset time is less than the throttle preset opening difference.

[0022] In the above solution, the method for obtaining the running time of each cylinder of the engine in a certain crankshaft operating angle and calculating the average running time of each cylinder of the engine in a number of consecutive sampling periods is:

[0023] The crankshaft operating angle section is the crankshaft angle from 80° after the compression top dead center of each cylinder of the engine to 260° after the compression top dead center of its corresponding cylinder. The operating time of each cylinder of the engine in the crankshaft operating angle section is obtained; the operating time in several consecutive sampling periods is T n [0,1,2,3…], where n is the engine cylinder number; wherein the default initial value of the running time is 0;

[0024] The average running time of the running time in several consecutive sampling periods is t RawSegmentAvg [0,1,2…], where t RawSegmentAvg[0] is the average running time of the first cylinder of the engine.

[0025] In the above solution, the runtime update optimization process activation conditions include:

[0026] (1) The engine is in running state;

[0027] (2) All cylinders of the engine are in the fuel cut-off state;

[0028] (3) The engine does not directly participate in driving the vehicle;

[0029] (4) The engine does not experience knock or pre-ignition;

[0030] (5) The running time in several consecutive sampling periods is not 0;

[0031] (6) The engine did not malfunction.

[0032] In the above solution, the method of dividing the evaluation area according to the engine speed and determining the running time update coefficient according to the evaluation area is as follows:

[0033] The engine speed is divided into 10 evaluation areas as follows:

[0034]

[0035] Each cylinder of the engine has a corresponding running time update coefficient in each of the 10 evaluation areas; the running time update coefficients of the 10 evaluation areas are r n [0,1,2…,9], where n is the engine cylinder number, which can be saved after the vehicle is powered off, and its initial value is 1.

[0036] In the above scheme, the method for determining the value of the runtime update optimization counter and the initial value of the runtime update coefficient is:

[0037] If the runtime update optimization processing activation condition is not satisfied and the evaluation area changes, at least one of the two conditions is satisfied, the runtime update optimization counter Cnt is set to AdaptCounter Reset to 1 and update the running time coefficient to the initial value r raw [0,1,2…] Reset to the runtime update coefficient r stored at power-down n The specific value of the running time update coefficient of the current evaluation area in [0,1,2…,9]; where r raw [0] is the initial value of the engine's first cylinder operating time update coefficient, r raw [1] is the initial value of the running time update coefficient of the second cylinder of the engine, and so on;

[0038] If the activation condition of the running time update optimization process is not satisfied and the evaluation area changes, the running time update optimization counter Cnt is set after each sampling period of the running time. AdaptCounter The value of is increased by 1, where the runtime updates the optimization counter Cnt AdaptCounter The default initial value is 0, and the initial value r of the running time update coefficient is accumulated. raw [0, 1, 2…] are used as the initial values ​​of the new running time update coefficients. The accumulation method is as follows, taking the first cylinder of the engine as an example, and the other cylinders are similar:

[0039] The initial value of the operating time update coefficient of the first cylinder of the engine where r raw [0](z) is the initial value of the operating time update coefficient obtained in the previous sampling period, and Avg is the average value of the operating time average values ​​of all cylinders.

[0040] In the above scheme, the method for determining the value of the flag bit and determining the updated running time update coefficient is as follows:

[0041] Determine whether the running time in the current evaluation area has completed the first update. If the first update is not completed, the running time is accumulated in a weighted manner. The purpose of this design is that when the first update is not completed, the learning parameters are not stable, and the weighted approach is more stable and accurate. If the running time in the current evaluation area is updated, the optimization counter Cnt AdaptCounter The value is not less than the preset value Cnt A1 The number of times Cnt AdaptWeightCounter Greater than the preset number Cnt B1 When the running time is updated for the first time, the flag bit b FirstAdaptDone The value is 1; otherwise, the flag bit b FirstAdaptDone The value of is 0; wherein, the runtime update optimization counter Cnt AdaptCounter The value is not less than the preset value Cnt A1 The number of times Cnt AdaptWeightCounter The value of is obtained by updating the cumulative method, and the updating cumulative method is: the number of times Cnt AdaptWeightCounter The default value is 0, and the optimization counter Cnt is updated at runtime. AdaptCounter After reset, the running time is accumulated again and the optimization counter Cnt is updated. AdaptCounter Not less than the preset value Cnt A1 After that, the number of times Cnt AdaptWeightCounter The value of is added by 1, that is, each time the running time updates the optimization counter Cnt AdaptCounter After reset, the runtime update optimization counter Cnt AdaptCounterUpdate at most once; the number of times Cnt AdaptWeightCounter and the flag bit b FirstAdaptDone The default value is 0, and all will be saved after the vehicle is powered off;

[0042] In the flag bit b FirstAdaptDone The value of is 0, and the runtime update optimization counter Cnt AdaptCounter The value is not less than the preset value Cnt A1 Only when the running time update coefficient r is updated is it allowed to update n [0,1,2…,9]; the update of the running time update coefficient r n The method for [0,1,2…,9] is:

[0043] Taking the current evaluation area as 0 as an example, the methods for other evaluation areas are similar; update the running time update coefficient r when the current evaluation area is 0 n [0] = k AdaptWeight ×r raw [n]+(1-k AdaptWeight )×r n [0](z); where r raw [n] is the initial value r of the running time update coefficient raw The value of the n+1th cylinder in [0,1,2…]; where r n [0](z) is the specific value of the running time update coefficient when the evaluation area is 0 in the previous sampling period; where k AdaptWeight is the weighted coefficient; similarly, the updated running time update coefficients of other evaluation areas can be obtained, which is the updated running time update coefficient r n [0,1,2…,9];

[0044] In the flag bit b FirstAdaptDone When the value of is 1, and the runtime updates the optimization counter Cnt AdaptCounter The value is not less than the preset value Cnt A2 Only when the running time update coefficient r is updated is it allowed to update n [0,1,2…,9], where Cnt A2 Not less than Cnt A1 ; The update of the running time update coefficient r n The method for [0,1,2…,9] is:

[0045] Taking the current evaluation area as 0 as an example, the methods for other evaluation areas are similar; update the running time update coefficient r when the current evaluation area is 0 n [0] = k Adapt ×r raw [n]+(1-k Adapt )×r n[0](z); where r raw [n] is the initial value r of the running time update coefficient raw The value of the n+1th cylinder in [0,1,2…]; where r n [0](z) is the specific value of the running time update coefficient when the evaluation area is 0 in the previous sampling period; where k Adapt is the weighting coefficient, and k Adapt No more than k AdaptWeight Similarly, the updated running time update coefficients of other evaluation areas can be obtained, which are the updated running time update coefficients r n [0,1,2…,9].

[0046] In the above scheme, the method for determining the final running time is:

[0047] In the flag bit b FirstAdaptDone When the value of is 0, the final running time T n-New is the running time;

[0048] In the flag bit b FirstAdaptDone When the value is 1, the final running time T n-New It is the product of the running time and the specific value of the updated running time update coefficient in the current evaluation area.

[0049] In the above solution, the method for obtaining the characteristic coefficient is: the average final running time of each cylinder of the engine in several consecutive sampling periods is T n_Avg , find the maximum value of the final running time average value T max , the minimum value is T min .

[0050] In the above scheme, the characteristic coefficient r CynDetectRaw For several consecutive sampling periods (T max -T min ) / T min The average value of the self-learning correction coefficient k Adapt The default initial value is 0, which will be saved after the vehicle is powered off.

[0051] In the above scheme, the method for determining the value of the initial flag of the fixed cylinder according to the characteristic coefficient and the self-learning correction coefficient is: if r CynDetectRaw (1+k Adapt )≥r CynDetectOffLim , then the initial flag bit bCynOffRaw The value is 1, otherwise the initial flag bCynOffRaw The value of r is 0; CynDetectOffLimThe threshold coefficient is used to judge the continuous oil cut-off of the fixed cylinder. The threshold coefficient is obtained on the test bench. The specific method is as follows: the threshold coefficient is determined by the average engine speed and the average engine intake density. On the engine test bench, the self-learning correction coefficient k Adapt Under the premise of being 0, read the characteristic coefficient r under the active oil cut-off condition CynDetectRaw and the characteristic coefficient r without oil cut-off CynDetectRaw The minimum value of the average value of the characteristic coefficient under the active oil cut-off condition and the characteristic coefficient under the non-oil cut-off condition obtained by multiple samplings is taken as the threshold coefficient r for judging the continuous oil cut-off of the fixed cylinder. CynDetectOffLim ; wherein the average engine speed and the average engine intake density are respectively the average values ​​of the current sampling period and the four sampling periods before it, a total of five sampling periods; according to the test bench, multiple samplings are performed, and the fixed cylinder continuous oil cut-off is actively set at different engine speeds and different engine intake densities, and the minimum value of the threshold coefficient obtained in multiple samplings is used as the threshold coefficient.

[0052] In the above solution, the value of the final flag of the fixed cylinder is determined according to the value of the initial flag, and the method for judging whether the fixed cylinder has truly been cut off from fuel according to the value of the final flag is as follows:

[0053] In the initial flag bCynOffRaw The value of is 1, if:

[0054] The first case: There is an average final running time T of the engine cylinder in several consecutive sampling periods. n_Avg With T max Equal; and determine its cylinder number;

[0055] Second case: Under the conditions of the first case, there is a preset value X>(T max -T n_Avg ) / T max >0, determine its cylinder number;

[0056] The third case: the final running time T of the cylinder that meets the first or second case within several consecutive sampling cycles n-New All meet (T max -T n-New ) / T max Within the preset range Y;

[0057] Case 4: At least one cylinder does not meet the conditions of case 1 or case 2;

[0058] Fifth case: The cylinder numbers that meet the first or second case are recorded in the order of cylinder work. If the number of cylinders that do not meet the first or second case between two consecutive cylinder numbers that meet the first or second case is not less than 2, then T n_Avg With T min The cylinder number that is equal is not the next working cylinder number that satisfies the first condition or the second condition;

[0059] If the first condition, the second condition, the third condition, the fourth condition, and the fifth condition are all satisfied, then the final flag position b of the cylinder that satisfies the first condition or the second condition is CynOff The value of 1 indicates that the fixed cylinder has a real oil cut-off; the final flag bit b of other cylinders CynOff The value of 0 indicates that the fixed cylinder does not actually experience oil cut-off.

[0060] The present invention provides a method for identifying dynamic fuel cut-off of an engine. The method can be based on the engine running time and continuously optimized to identify in real time whether a cylinder or multiple cylinders have dynamically cut off fuel (continuous misfire), thereby reminding the driver to perform maintenance and inspection in time, and also protecting the engine in time. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. Throughout the drawings, the same reference figures denote the same components. In the drawings:

[0062] Figure 1 The figure is a flow chart of a method for identifying dynamic fuel cut-off of an engine according to an embodiment of the present invention. DETAILED DESCRIPTION

[0063] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining 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 may be combined with each other as long as they do not conflict with each other.

[0064] It should be understood that the size of the serial numbers of the steps in the embodiment 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 embodiment of the present application.

[0065] Example 1

[0066] On the one hand, the present invention provides a method for identifying dynamic fuel cut-off of an engine. Figure 1 ,include:

[0067] S1, when the enabling conditions of the engine dynamic fuel cut-off verification method are met, the operating time of each cylinder of the engine in a crankshaft operating angle is obtained, and the average operating time of each cylinder of the engine in several consecutive sampling periods is calculated.

[0068] Specifically, in this embodiment, to ensure the accuracy and safety of the engine dynamic fuel cut-off verification method, the engine dynamic fuel cut-off verification method of the present invention needs to be performed under enabling conditions. In the present invention, the enabling condition judgment sampling period is 10ms. The engine dynamic fuel cut-off verification method enabling conditions include:

[0069] (1) Enter the fire diagnosis area specified in the regulations;

[0070] (2) No fuel cut-off request;

[0071] (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;

[0072] (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;

[0073] (5) Non-uneven road surface;

[0074] (6) Water temperature is higher than -6℃;

[0075] (7) The throttle opening fluctuation is small during the diagnosis process, and the difference between the maximum and minimum throttle openings within 0.1s is less than 15%;

[0076] (8) The engine is in running state.

[0077] Once the above conditions are met, the dynamic engine fuel shutoff verification method can be performed. If the above conditions are not met, the vehicle's operating conditions may cause misjudgment. If the enabling conditions are not met during the diagnostic process, the diagnosis is terminated and the dynamic engine fuel shutoff verification method will be performed again when the diagnostic conditions are met again.

[0078] Specifically, in this embodiment, the method for obtaining the running time of each cylinder of the engine in a crankshaft operating angle range is as follows: a crankshaft operating angle range is from 80° after the compression top dead center of each cylinder of the engine to 260° after the compression top dead center of its corresponding cylinder, and the running time of each cylinder of the engine in this crankshaft operating angle range is obtained. The running time in a number of consecutive sampling periods is T n[0, 1, 2, 3…], where n is the cylinder number; the default initial value of the running time is 0; the running time T n The values ​​of [0, 1, 2, 3…] will be continuously updated; n [0] represents the running time of each cylinder of the engine at the current sampling time, T n [1] represents the running time of each cylinder of the engine in the last sampling, and so on. In particular, all subsequent sampling steps are for each cylinder from the crankshaft angle of 80° after compression top dead center to 260° after compression top dead center, that is, the crankshaft rotates 180°.

[0079] In this embodiment, the number of engine cylinders is 4, and the average running time of each cylinder of the engine in 10 consecutive sampling periods is calculated. RawSegmentAvg [0,1,2,3], where t RawSegmentAvg [0] is the average running time of the first cylinder of the engine, and so on.

[0080] S2: When the activation conditions for the run time update optimization process are met, a fuel cut-off request is made to all cylinders of the engine; an evaluation region is divided according to the engine speed, and a run time update coefficient is determined according to the evaluation region.

[0081] Specifically, in this embodiment, the runtime update optimization process activation conditions include:

[0082] (1) The engine is in running state;

[0083] (2) All cylinders of the engine are in the fuel cut-off state;

[0084] (3) The engine is not directly involved in driving the vehicle, that is, the engine is not connected to the transmission system;

[0085] (4) The engine does not experience knock or pre-ignition;

[0086] (5) The running time in 10 consecutive sampling periods is not 0;

[0087] (6) The engine did not malfunction.

[0088] In this embodiment, the update check period for judging the activation condition of the run time update optimization process is 10 ms. A fuel cut-off request can be made to all cylinders of the engine only when the activation condition of the run time update optimization process is satisfied.

[0089] Specifically, in this embodiment, the evaluation regions are divided according to the engine speed, and the method for determining the running time update coefficient according to the evaluation regions is as follows:

[0090] The engine speed is divided into 10 evaluation areas as follows:

[0091]

[0092]

[0093] Each cylinder of the engine has a specific value of the running time update coefficient in each of the 10 evaluation areas. The running time update coefficients of the 10 evaluation areas are r n [0, 1, 2, ..., 9], where n is the engine cylinder number, which is saved after the vehicle is powered off and has an initial value of 1. Specifically, if the engine speed is 750 rpm or less, the current evaluation area is 0. If the engine speed is greater than 750 rpm and not less than 1000 rpm, the current evaluation area is 1, and so on.

[0094] S3, judging whether the activation condition and evaluation area of ​​the runtime update optimization process have changed, and determining the value of the runtime update optimization counter and the initial value of the runtime update coefficient according to the runtime update coefficient and the average runtime value.

[0095] Specifically, in this embodiment, if at least one of the following two conditions is met: the runtime update optimization processing activation condition is not met and the evaluation area changes, the runtime update optimization counter Cnt is set to AdaptCounter Reset to 1 and update the running time coefficient to the initial value r raw [0,1,2,3] Reset to the running time update coefficient r stored at power-off n The specific value of the running time update coefficient of the current evaluation area in [0,1,2…,9]; where r raw [0] is the initial value of the engine's first cylinder operating time update coefficient, r raw [1] is the initial value of the operating time update coefficient of the second cylinder of the engine, and so on.

[0096] If the activation condition of the runtime update optimization process is not met and the evaluation area changes, the runtime update optimization counter Cnt will be set after each sampling period of the runtime. AdaptCounter The value of is increased by 1, where the runtime updates the optimization counter Cnt AdaptCounter The default initial value is 0, and the initial value of the coefficient r is updated by accumulating the running time raw [0, 1, 2, 3] are used as the initial values ​​of the new running time update coefficients. The accumulation method is as follows, taking the first cylinder of the engine as an example, and the other cylinders are similar:

[0097] Initial value of the engine's first cylinder operating time update coefficient where r raw [0](z) is the initial value of the running time update coefficient obtained in the previous sampling period, t RawSegmentAvg[0] is the average running time of the first cylinder of the engine, and Avg is the average running time of all cylinders, that is,

[0098]

[0099] S4, determining the value of the flag bit according to the value of the runtime update optimization counter; determining the updated runtime update coefficient according to the value of the flag bit, the initial value of the runtime update coefficient, and the runtime update coefficient.

[0100] Specifically, in this embodiment, if the running time in the current evaluation area is updated, the optimization counter Cnt AdaptCounter The value is not less than the preset value Cnt A1 The number of times Cnt AdaptWeightCounter Greater than the preset number Cnt B1 When the running time is completed, it means that the first update is completed. At this time, the flag bit b FirstAdaptDone The value is 1; otherwise, the flag bit b FirstAdaptDone The value of Cnt is 0; in this embodiment, the preset value Cnt A1 The preset number is 5, Cnt B1 is 3.

[0101] Among them, the number of times Cnt AdaptWeightCounter The value is obtained by updating the cumulative method, which is: running time update optimization counter Cnt AdaptCounter The value is not less than the preset value Cnt A1 The number of times Cnt AdaptWeightCounter The default value is 0, and the optimization counter Cnt is updated at runtime. AdaptCounter After reset, the running time is accumulated again and the optimization counter Cnt is updated. AdaptCounter Not less than the preset value Cnt A1 After that, the runtime updates the optimization counter Cnt AdaptCounter The value of is increased by 1, that is, the optimization counter Cnt is updated every time the running time is AdaptCounter After reset, the runtime update optimization counter Cnt AdaptCounter Update at most once; the number of times is Cnt AdaptWeightCounter and flag bit b FirstAdaptDone The default value is 0, and all values ​​will be saved after the vehicle is powered off.

[0102] In the flag bit b FirstAdaptDone The value is 0, and the runtime update optimization counter Cnt AdaptCounter The value is not less than the preset value Cnt A1 Only when the running time update coefficient r is updated n [0,1,2…,9]; Update the running time update coefficient r n The method for [0,1,2…,9] is:

[0103] Taking the current evaluation area as 0 as an example, the methods for other evaluation areas are similar; update the running time update coefficient r when the current evaluation area is 0 n [0] = k AdaptWeight ×r raw [n]+(1-k AdaptWeight )×r n [0](z); where r raw [n] is the initial value of the running time update coefficient r raw The value of the n+1th cylinder in [0,1,2,3]; where r n [0](z) is the specific value of the running time update coefficient when the evaluation area is 0 in the previous sampling period (i.e., the running time update coefficient r n When the evaluation area is 0 in [0,1,2,...,9], r n [0]); where k AdaptWeight is the weighting coefficient, which is 0.15 in this example; similarly, the updated running time update coefficients of other evaluation areas can be obtained, which is the updated running time update coefficient r n [0,1,2…,9].

[0104] In the flag bit b FirstAdaptDone When the value is 1, and the runtime update optimization counter Cnt AdaptCounter The value is not less than the preset value Cnt A2 Only when the running time update coefficient r is updated n [0,1,2…,9], where Cnt A2 Not less than Cnt A1 In this embodiment, Cnt A2 =16; Update running time update coefficient r n The method for [0,1,2…,9] is:

[0105] Taking the current evaluation area as 0 as an example, the methods for other evaluation areas are similar; update the running time update coefficient r when the current evaluation area is 0 n [0] = k Adapt ×r raw [n]+(1-k Adapt )×r n [0](z); where r raw [n] is the initial value of the running time update coefficient r raw The value of the n+1th cylinder in [0,1,2,3]; where r n [0](z) is the specific value of the running time update coefficient when the evaluation area is 0 in the previous sampling period (i.e., the running time update coefficient r n When the evaluation area is 0 in [0,1,2,...,9], rn [0]); where k Adapt is the weighting coefficient, which is 0.005 in this example, and k Adapt No more than k AdaptWeight Similarly, the updated running time update coefficients of other evaluation areas can be obtained, which are the updated running time update coefficients r n [0,1,2…,9].

[0106] S5, determining the final running time according to the value of the flag bit, the updated running time update coefficient and the running time.

[0107] Specifically, in this embodiment, the method for determining the final running time is:

[0108] In the flag bit b FirstAdaptDone When the value is 0, the final running time T n-New is the running time T n [0,1,2,3…];

[0109] In the flag bit b FirstAdaptDone When the value is 1, the final running time is T n-New is the running time T n [0,1,2,3…] multiplied by the updated runtime update coefficient in the current evaluation area.

[0110] S6, calculating the average final running time of each cylinder of the engine in several consecutive sampling periods based on the final running time, and calculating the characteristic coefficient; determining the value of the initial flag of the fixed cylinder based on the characteristic coefficient and the self-learning correction coefficient.

[0111] Specifically, in this embodiment, the final running time average value of each cylinder of the engine in 5 consecutive sampling periods is calculated, and each cylinder is calculated separately to obtain the final running time average value T of each cylinder. n_Avg :

[0112]

[0113] Among them, the maximum value of the average final running time of each cylinder of the engine is T max , the minimum value is T min : In this example, if the engine is a 4-cylinder engine, then:

[0114] T Max =max(T 1_Avg , T 2_Avg , T 3_Avg , T 4_Avg );

[0115] T Min =min(T 1_Avg , T2_Avg , T 3_Avg , T 4_Avg ).

[0116] In this embodiment, the characteristic coefficient r CynDetectRaw The current sampling period The average value of the 5 sampling cycles including the 4 sampling cycles before it. Self-learning correction coefficient k Adapt The default initial value is 0, which will be saved after the vehicle is powered off. CynDetectOffLim The threshold coefficient is used to judge the continuous oil cut-off of the fixed cylinder. The threshold coefficient is obtained on the test bench. The specific method is as follows: the threshold coefficient is determined by the average engine speed and the average engine intake density. On the engine test bench, the self-learning correction coefficient k Adapt Under the premise of being 0, read the characteristic coefficient r under active oil cut-off CynDetectRaw and the characteristic coefficient r under the condition of no oil interruption CynDetectRaw The minimum value of the average value of the characteristic coefficients under active oil cut-off and the characteristic coefficients under non-oil cut-off of multiple samplings is taken as the threshold coefficient r for judging the continuous oil cut-off of the fixed cylinder. CynDetectOffLim The average engine speed and average engine intake air density are the averages of the current sampling cycle and the four preceding sampling cycles, totaling five sampling cycles. Multiple sampling runs are performed on the test bench. Continuous fuel cutoff is actively set for a fixed cylinder at different engine speeds and different engine intake air densities. The minimum threshold coefficient value obtained from these multiple sampling runs is used as the threshold coefficient.

[0117] According to the characteristic coefficient r CynDetectRaw and self-learning correction coefficient k Adapt The method for determining the value of the initial flag of the fixed cylinder is: if r CynDetectRaw (1+k Adapt )≥r CynDetectOffLim , then the initial flag bCynOffRaw The value is 1, otherwise the initial flag bCynOffRaw The value of is 0.

[0118] S7, determining the value of the final flag of the fixed cylinder according to the value of the initial flag, and judging whether the fixed cylinder has truly been cut off from fuel according to the value of the final flag.

[0119] Specifically, in this embodiment, the method for determining the final flag value of the fixed cylinder according to the value of the initial flag is as follows: bCynOffRaw The value of is 1, if:

[0120] Case 1: There is an average final running time T of the engine cylinder in 5 consecutive sampling cycles. n_Avg With T max Equal; and determine its cylinder number;

[0121] Second case: Under the conditions of the first case, there is a preset value X>(T max -T n_Avg ) / T max >0, determine its cylinder number; in this example, the preset value X is 0.05;

[0122] The third case: the final running time T of the cylinder that meets the first or second case within 5 consecutive sampling cycles n-New All meet (T max -T n-New ) / T max Within the preset range Y; in this example, the preset range Y is 0.08;

[0123] Case 4: At least one cylinder does not meet the conditions of case 1 or case 2;

[0124] Fifth case: The cylinder numbers that meet the first or second case are recorded in the order of cylinder work. If the number of cylinders that do not meet the first or second case between two consecutive cylinder numbers that meet the first or second case is not less than 2, then T n_Avg With T min The cylinder number that is equal is not the next working cylinder number that satisfies the first or second case. For example, in this example, the engine is a 4-cylinder engine, and the cylinder working order is 1-3-4-2-1-3-4-2-…. The cylinder numbers that meet the first or second case are cylinder 1 and cylinder 2, and the middle working cylinders are cylinder 3 and cylinder 4. Then the T corresponding to cylinder 4 is 4_Avg Not equal to T Min .

[0125] If the first, second, third, fourth and fifth conditions are all met, the final flag position b of the cylinder that meets the first or second condition is CynOff The value of 1 indicates that the fixed cylinder has a real oil cut; the final flag bit b of other cylinders CynOff The value of 0 indicates that there is no real oil cut-off in the fixed cylinder.

[0126] In summary, the engine dynamic fuel cut-off identification method provided by the present invention can detect whether the engine has a fixed cylinder fuel cut-off, thereby reminding the driver to perform maintenance and inspection in time to protect the engine.

[0127] It should be pointed out that, according to the needs of implementation, the various steps described in this application can be split into more steps, or two or more steps or partial operations of the steps can be combined into new steps to achieve the purpose of the present invention.

[0128] It will be easily understood by those skilled in the art that the above description is merely 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 scope of protection of the present invention.

Claims

1. A method for identifying dynamic fuel cut-off of an engine, characterized in that: include: When the enabling conditions of the engine dynamic fuel cut-off verification method are met, the operating time of each cylinder of the engine in a range of crankshaft operating angles is obtained, and the average operating time of each cylinder of the engine in a plurality of consecutive sampling periods is calculated; When the activation conditions for the run time update optimization process are met, requesting fuel cutoff for all cylinders of the engine, dividing the evaluation area according to the engine speed, and determining the run time update coefficient according to the evaluation area; Determining whether the activation condition for the run time update optimization process and the evaluation area have changed, and determining a value of a run time update optimization counter and an initial value of the run time update coefficient according to the run time update coefficient and the run time average value; Determine the value of the flag bit according to the value of the runtime update optimization counter; Determine an updated runtime update coefficient according to the value of the flag bit, the initial value of the runtime update coefficient, and the runtime update coefficient; Determine a final running time according to the value of the flag bit, the updated running time update coefficient, and the running time; Calculating an average value of the final operating time of each cylinder of the engine in a plurality of consecutive sampling periods according to the final operating time to calculate a characteristic coefficient; Determining the value of the initial flag of the fixed cylinder according to the characteristic coefficient and the self-learning correction coefficient; The value of the final flag of the fixed cylinder is determined according to the value of the initial flag, and whether the fixed cylinder is truly fuel-off is determined according to the value of the final flag.

2. The method for identifying dynamic fuel cut-off of an engine according to claim 1, characterized in that: The method for obtaining the running time of each cylinder of the engine in a certain crankshaft operating angle and calculating the average running time of each cylinder of the engine in a number of consecutive sampling periods is as follows: The crankshaft operating angle section is the crankshaft angle from 80° after the compression top dead center of each cylinder of the engine to 260° after the compression top dead center of its corresponding cylinder. The operating time of each cylinder of the engine in the crankshaft operating angle section is obtained. The operating time within a number of consecutive sampling periods is T n [0,1,2,3…], where n is the engine cylinder number; The default initial value of the running time is 0; The average running time of the running time in several consecutive sampling periods is t RawSegmentAvg [0,1,2…], where t RawSegmentAvg [0] is the average running time of the first cylinder of the engine.

3. The method for identifying dynamic fuel cut-off of an engine according to claim 2, characterized in that: The evaluation area is divided according to the engine speed, and the method for determining the running time update coefficient according to the evaluation area is as follows: The method of dividing the engine speed into the following 10 evaluation areas is as follows: when the engine speed values ​​are 750 rpm, 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm, and 5000 rpm, the corresponding evaluation areas are 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9; Each cylinder of the engine has a corresponding running time update coefficient in each of the 10 evaluation areas; the running time update coefficients of the 10 evaluation areas are r n [0,1,2…,9], where n is the engine cylinder number, which can be saved after the vehicle is powered off, and its initial value is 1.

4. The method for identifying dynamic fuel cut-off of an engine according to claim 3, characterized in that: The method for determining the value of the runtime update optimization counter and the initial value of the runtime update coefficient is: If the runtime update optimization processing activation condition is not satisfied and the evaluation area changes, at least one of the two conditions is satisfied, the runtime update optimization counter Cnt is set to AdaptCounter Reset to 1 and update the running time coefficient to the initial value r raw [0,1,2…] Reset to the runtime update coefficient r stored at power-down n The specific value of the running time update coefficient of the current evaluation area in [0,1,2…,9]; where r raw [0] is the initial value of the engine's first cylinder operating time update coefficient, r raw [1] is the initial value of the running time update coefficient of the second cylinder of the engine, and the same applies to the other cylinders; If the activation condition of the running time update optimization process is not satisfied and the evaluation area changes, the running time update optimization counter Cnt is set after each sampling period of the running time. AdaptCounter The value of is increased by 1, where the runtime updates the optimization counter Cnt AdaptCounter The default initial value is 0, and the initial value r of the running time update coefficient is accumulated. raw [0,1,2…] as the new initial value of the runtime update coefficient; The accumulation method is as follows: The initial value of the operating time update coefficient of the first cylinder of the engine where r raw [0](z) is the initial value of the operating time update coefficient obtained in the previous sampling period, Avg is the average value of the operating time average values ​​of all cylinders, and the method for the remaining cylinders is the same as that for the first cylinder of the engine.

5. The method for identifying dynamic fuel cut-off of an engine according to claim 4, characterized in that: The method for determining the flag value and the updated running time update coefficient is as follows: If the running time in the current evaluation area updates the optimization counter Cnt AdaptCounter The value is not less than the preset value Cnt A1 The number of times Cnt AdaptWeightCounter Greater than the preset number Cnt B1 When the running time is updated for the first time, the flag bit b FirstAdaptDone The value of is 1; Otherwise, flag bit b FirstAdaptDone The value of is 0; wherein, the runtime update optimization counter Cnt AdaptCounter The value is not less than the preset value Cnt A1 The number of times Cnt AdaptWeightCounter The value of is obtained by updating the cumulative method, and the updating cumulative method is: the number of times Cnt AdaptWeightCounter The default value is 0, and the optimization counter Cnt is updated at runtime. AdaptCounter After reset, the running time is accumulated again and the optimization counter Cnt is updated. AdaptCounter Not less than the preset value Cnt A1 After that, the number of times Cnt AdaptWeightCounter The value of is added by 1, that is, each time the running time updates the optimization counter Cnt AdaptCounter After reset, the runtime update optimization counter Cnt AdaptCounter Update at most once; the number Cnt AdaptWeightCounter and the flag bit b FirstAdaptDone The default value is 0, and all will be saved after the vehicle is powered off; In the flag bit b FirstAdaptDone The value of is 0, and the runtime update optimization counter Cnt AdaptCounter The value is not less than the preset value Cnt A1 Only when the running time update coefficient r is updated is it allowed to update n [0,1,2…,9]; the update of the running time update coefficient r n The method for [0,1,2…,9] is: Update the running time update coefficient r of the current evaluation area to 0 n [0] = k AdaptWeight ×r raw [n]+(1-k AdaptWeight )×r n [0](z); where r raw [n] is the initial value r of the running time update coefficient raw The value of the n+1th cylinder in [0,1,2…]; where r n [0](z) is the specific value of the running time update coefficient when the evaluation area is 0 in the previous sampling period; where k AdaptWeight is the weighting coefficient; similarly, the updated running time update coefficients of other evaluation areas can be obtained, that is, the updated running time update coefficient r n [0,1,2…,9], the update method of the running time update coefficient of the remaining evaluation areas is the same as that of the evaluation area 0; In the flag bit b FirstAdaptDone When the value of is 1, and the runtime updates the optimization counter Cnt AdaptCounter The value is not less than the preset value Cnt A2 Only when the running time update coefficient r is updated is it allowed to update n [0,1,2…,9], where Cnt A2 Not less than Cnt A1 ; The update of the running time update coefficient r n The method for [0,1,2…,9] is: Update the running time update coefficient r of the current evaluation area to 0 n [0] = k Adapt ×r raw [n]+(1-k Adapt )×r n [0](z); where r raw [n] is the initial value r of the running time update coefficient raw The value of the n+1th cylinder in [0,1,2…]; where r n [0](z) is the specific value of the running time update coefficient when the evaluation area is 0 in the previous sampling period; where k Adapt is the weighting coefficient, and k Adapt No greater than k AdaptWeight Similarly, the updated running time update coefficients of other evaluation areas can be obtained, which are the updated running time update coefficients r n [0,1,2…,9], the update method of the running time update coefficient of the remaining evaluation areas is the same as that of the evaluation area 0.

6. The method for identifying dynamic fuel cut-off of an engine according to claim 5, characterized in that: The method for determining the final running time is: In the flag bit b FirstAdaptDone When the value of is 0, the final running time T n-New is the running time; In the flag bit b FirstAdaptDone When the value is 1, the final running time T n-New It is the product of the running time and the specific value of the updated running time update coefficient in the current evaluation area.

7. The method for identifying dynamic fuel cut-off of an engine according to claim 6, characterized in that: The method for obtaining the characteristic coefficient is as follows: the average final running time of each cylinder of the engine in a number of consecutive sampling periods is T n_Avg , find the maximum value of the final running time average value T max , the minimum value is T min ; The characteristic coefficient r CynDetectRaw For several consecutive sampling periods (T max -T min ) / T min The average value of the self-learning correction coefficient k Adapt The default initial value is 0, which will be saved after the vehicle is powered off; The method for determining the value of the initial flag of the fixed cylinder according to the characteristic coefficient and the self-learning correction coefficient is as follows: if r CynDetectRaw (1+k Adapt )≥r CynDetectOffLim , then the value of the initial flag bit bCynOffRaw is 1, otherwise the value of the initial flag bit bCynOffRaw is 0; wherein r CynDetectOffLim The threshold coefficient is used to judge the continuous oil cut-off of the fixed cylinder. The threshold coefficient is obtained on the test bench. The specific method is as follows: the threshold coefficient is determined by the average engine speed and the average engine intake density. On the engine test bench, the self-learning correction coefficient k Adapt Under the premise of being 0, read the characteristic coefficient r under the active oil cut-off condition CynDetectRaw and the characteristic coefficient r without oil cut-off CynDetectRaw The minimum value of the average value of the characteristic coefficient under the active oil cut-off condition and the characteristic coefficient under the non-oil cut-off condition obtained by multiple samplings is taken as the threshold coefficient r for judging the continuous oil cut-off of the fixed cylinder. CynDetectOffLim ; wherein the average engine speed and the average engine intake density are respectively the average values ​​of the current sampling period and the four sampling periods before it, a total of five sampling periods; according to the test bench, multiple samplings are performed, and the fixed cylinder continuous oil cut-off is actively set at different engine speeds and different engine intake densities, and the minimum value of the threshold coefficient obtained in multiple samplings is used as the threshold coefficient.

8. The method for identifying dynamic fuel cut-off of an engine according to claim 7, characterized in that: The method of determining the value of the final flag of the fixed cylinder according to the value of the initial flag, and judging whether the fixed cylinder has truly been cut off from fuel according to the value of the final flag is as follows: On the premise that the value of the initial flag bit bCynOffRaw is 1, if: The first case: There is an average final running time T of the engine cylinder in several consecutive sampling periods. n_Avg With T max Equal; and determine its cylinder number; Second case: Under the conditions of the first case, there is a preset value X>(T max -T n_Avg ) / T max >0, determine its cylinder number; The third case: the final running time T of the cylinder that meets the first or second case within several consecutive sampling cycles n-New All meet (T max -T n-New ) / T max Within the preset range Y; Case 4: At least one cylinder does not meet the conditions of case 1 or case 2; Fifth case: The cylinder numbers that meet the first or second case are recorded in the order of cylinder work. If the number of cylinders that do not meet the first or second case between two consecutive cylinder numbers that meet the first or second case is not less than 2, then T n_Avg With T min The cylinder number that is equal is not the next working cylinder number that satisfies the first condition or the second condition; If the first condition, the second condition, the third condition, the fourth condition, and the fifth condition are all satisfied, then the final flag position b of the cylinder that satisfies the first condition or the second condition is CynOff The value of 1 indicates that the fixed cylinder has a real oil cut-off; Final mark position b of other cylinders CynOff The value of 0 indicates that the fixed cylinder does not actually experience oil cut-off.

9. The method for identifying dynamic fuel cut-off of an engine according to claim 1, characterized in that: The enabling conditions of the engine dynamic fuel cut-off verification method include: (1) Enter the fire diagnosis area specified in the regulations; (2) No fuel cut-off request; (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 running state; The gear position has not changed, which means that after 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, which 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, which 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.

10. The method for identifying dynamic fuel cut-off of an engine according to claim 1, characterized in that: The runtime update optimization process activation conditions include: (1) The engine is in running state; (2) All cylinders of the engine are in the fuel cut-off state; (3) The engine does not directly participate in driving the vehicle; (4) The running time in several consecutive sampling periods is not 0; (5) There is no engine failure.

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