Engine diagnosis method and engine diagnosis device

Abstract

To ensure diagnostic accuracy for engine torque states, regardless of engine operation states.SOLUTION: There is provided an engine diagnosis method of calculating corrected command torque Ttrg2 by correcting with a correction amount according to the response characteristics of engine torque T, and comparing diagnostic torque Tdia determined on the basis of the corrected command torque Ttrg2 with a torque estimate value Tact to diagnose the state of the engine torque T. In particular, in this engine diagnosis method, it is determined whether a current state is the time when the engine torque T increases or the time when the engine torque decreases, on the basis of a past value Ttrg2_(n) of the corrected command torque Ttrg2. At the time when the engine torque increases, a first filter (62, 72) is applied to the command torque Ttrg to calculate the corrected command torque Ttrg2, and at the time when the engine torque decreases, a second filter (64, 74) is applied to the command torque Ttrg to calculate the corrected command torque Ttrg2.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an engine diagnostic method and an engine diagnostic device. [Background technology]

[0002] Patent Document 1 discloses a method for monitoring the difference between a target torque and a torque estimate value of an engine mounted on a vehicle, and when the difference exceeds a certain level, it is determined that excessive torque is being output (abnormal torque state), and the engine is diagnosed as abnormal. In particular, the method of Patent Document 1 corrects the target torque determined from the driver's accelerator opening and engine speed by applying a predetermined filter, and diagnoses the state of the engine torque by monitoring the difference between the corrected target torque and the torque estimate value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-105305 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the response characteristics (tracking performance) of the engine torque actually output with respect to the target torque change depending on the engine operating conditions, such as the magnitude of the engine torque and the engine speed. For this reason, in the method described in Patent Document 1, the corrected target torque calculated by uniformly applying a filter to the target torque may deviate from the behavior of the actual engine torque depending on the engine operating conditions. As a result, there is a problem in that it is not possible to ensure sufficient accuracy in diagnosing the torque state based on the difference between the corrected target torque and the torque estimate value.

[0005] Therefore, an object of the present invention is to ensure diagnostic accuracy for the state of engine torque, regardless of the operating state of the engine. [Means for solving the problem]

[0006] According to one aspect of the present invention, a method is provided for diagnosing the state of engine torque by calculating a corrected command torque by correcting the command torque of an engine with a correction amount according to the response characteristic of the engine torque actually output, and comparing a diagnostic torque determined based on the corrected command torque with a torque estimate value. In this engine diagnosis method, it is determined whether the current state is an increase or decrease in engine torque based on a past value of the corrected command torque. If it is determined that the current state is an increase, a first filter is applied to the command torque to calculate the corrected command torque. On the other hand, if it is determined that the current state is a decrease, a second filter is applied to the command torque to calculate the corrected command torque. In particular, the first filter is defined by a first filter parameter defined according to the response characteristic when the engine torque increases. Moreover, the second filter is defined by a second filter parameter defined according to the response characteristic when the engine torque decreases. Effect of the Invention

[0007] According to the present invention, it is possible to ensure diagnostic accuracy for the state of engine torque, regardless of the operating state of the engine (particularly, increase or decrease in engine torque). [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the overall configuration of an engine to which an engine diagnostic method according to each embodiment of the present invention is applied. [Diagram 2] FIG. 2 is a flowchart showing an outline of the flow of engine control. [Diagram 3] FIG. 3 is a flowchart showing details of the abnormal torque determination process. [Figure 4] FIG. 4 is a block diagram illustrating a configuration for calculating torque for diagnosis according to the first embodiment. [Diagram 5] FIG. 5 is a flowchart showing details of the torque change determination process according to the first embodiment. [Figure 6] FIG. 6 is a map of the dead time and the first-order lag coefficient defined according to the engine speed. [Figure 7] FIG. 7 is a flowchart showing the overall process flow of the diagnostic torque calculation. [Figure 8] FIG. 8 is a map of the dead time and the first-order lag coefficient defined according to the engine torque. [Figure 9] FIG. 9 is a flowchart illustrating the effects of the control according to the first embodiment. [Figure 10] FIG. 10 is a block diagram illustrating a configuration for calculating torque for diagnosis according to the second embodiment. [Figure 11] FIG. 11 is a flowchart showing details of the torque change determination process according to the second embodiment. [Figure 12] FIG. 12 is a flowchart illustrating the effects of the control according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, engine control methods according to embodiments of the present invention will be described with reference to the drawings.

[0010] [First embodiment] (Overall engine configuration) 1 is a diagram showing the overall configuration of an engine 1 to which an engine diagnosis method according to this embodiment is applied. Note that this embodiment will be described on the assumption that the engine 1 is mounted on a vehicle as a driving source.

[0011] In this embodiment, the engine 1 is a direct injection engine and is configured to be able to directly inject fuel into the cylinders. The engine 1 is not limited to a direct injection engine, and may be a port injection engine that injects fuel into an intake port 4a of an intake passage 4. Although Fig. 1 shows only one cylinder for convenience, the number of cylinders is not limited to one and may be multiple.

[0012] The main body of the engine 1 is formed by a cylinder block 1A and a cylinder head 1B, and a cylinder or a cylinder is formed as a space surrounded by the cylinder block 1A and the cylinder head 1B.

[0013] A piston 2 is inserted into the cylinder block 1A so as to be able to reciprocate up and down along the cylinder center axis Ax, and the piston 2 is connected to a crankshaft (not shown) via a connecting rod 3. The reciprocating motion of the piston 2 is transmitted to the crankshaft via the connecting rod 3 and converted into the rotational motion of the crankshaft. A cavity is formed in a crown surface 21 of the piston 2. This cavity prevents the crown surface 21 of the piston 2 from interfering with the smooth flow of air taken into the cylinder through a port portion (intake port 4a) of the intake passage 4, while guiding the fuel injected by the fuel injection valve 6 along the wall surface of the cavity toward the spark plug 7.

[0014] The cylinder head 1B has a lower surface that defines a pent roof type combustion chamber Ch. The combustion chamber Ch is formed as a space surrounded by the lower surface of the cylinder head 1B and the crown surface 21 of the piston 2. The cylinder head 1B has a pair of intake passages 4 on one side of the cylinder center axis Ax and a pair of exhaust passages 5 on the other side, as passages that communicate the combustion chamber Ch with the outside of the engine 1. An intake valve 8 is disposed in a port portion (intake port) 4a of the intake passage 4, and an exhaust valve 9 is disposed in a port portion (exhaust port) 5a of the exhaust passage 5. Air taken in from the outside of the engine 1 into the intake passage 4 is sucked into the cylinder while the intake valve 8 is open, and the exhaust gas after combustion is discharged to the exhaust passage 5 while the exhaust valve 9 is open.

[0015] An electronic throttle device 41 is installed in the intake passage 4. This controls the flow rate of air taken into the cylinder via the intake passage 4. The electronically controlled throttle device 41 has a butterfly valve as a valve body, the rotating shaft of which is connected to an actuator (hereinafter referred to as the "throttle actuator") 301, and the rotational position of the valve body (hereinafter referred to as the "throttle opening") is controlled by the throttle actuator 301.

[0016] Further, in the cylinder head 1B, an ignition plug 7 is installed along the cylinder center axis Ax between the intake port 4a and the exhaust port 5a, and a fuel injection valve 6 is arranged between the pair of intake ports 4a, 4a on one side of the cylinder center axis Ax. The fuel injection valve 6 is configured and arranged so that fuel is supplied from a fuel accumulator (high-pressure fuel pipe) 302 that communicates with a fuel tank (not shown) and directly injects fuel into the cylinder.

[0017] A catalytic converter (not shown) is installed in the exhaust passage 5, and a catalyst for purifying exhaust gas is housed in the catalytic converter. In this embodiment, the exhaust gas purification device is a three-way catalyst, and the exhaust gas after combustion discharged into the exhaust passage 5 is purified by the exhaust gas purification catalyst to remove harmful components such as nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC), and then the exhaust gas is released into the atmosphere.

[0018] (Engine control system configuration) The operation of the engine 1 is controlled by an electronic control unit 50. The electronic control unit 50 is made up of a microcomputer equipped with a central processing unit (CPU), various storage devices such as RAM and ROM, an input / output interface, etc. Detection signals from an accelerator sensor 201, a rotational speed sensor 202, and a coolant temperature sensor 203 are input to the electronic control unit 50, as well as detection signals from an air flow meter 204, a throttle sensor 205, a combustion pressure sensor 206, and an air-fuel ratio sensor (not shown), etc.

[0019] Accelerator sensor 201 detects the amount of accelerator pedal operation by the driver (hereinafter referred to as "accelerator operation amount APO"). Accelerator operation amount APO is an index of the load required for engine 1. Rotation speed sensor 202 detects the rotation speed of engine 1. A crank angle sensor can be used as rotation speed sensor 202, and a signal output by the crank angle sensor for each unit crank angle (unit crank angle signal) or a signal output by the crank angle sensor for each reference crank angle (reference crank angle signal) is converted into the number of rotations per unit time (for example, the number of rotations per minute, hereinafter referred to as "engine rotation speed N e The rotation speed is detected by converting the engine coolant temperature into an engine speed (referred to as "rpm"). The coolant temperature sensor 203 detects the temperature of the engine coolant. Instead of the temperature of the engine coolant, the temperature of the engine lubricating oil may be used.

[0020] The air flow meter 204 is installed at the inlet of the intake passage 4 and detects the flow rate of air taken into the engine 1 (intake air volume). In this embodiment, the air flow meter 204 is configured as a hot wire flow meter. The throttle sensor 205 detects the rotational position (throttle opening) of the valve disc of the electronically controlled throttle device 41. In this embodiment, the throttle sensor 205 is configured as a potentiometer, and is assembled to the electronically controlled throttle device 41. The combustion pressure sensor 206 is installed in the high-pressure fuel pipe 302 and detects the pressure of the fuel supplied to the fuel injector 6. The air-fuel ratio sensor is installed in the exhaust passage 5 and detects the air-fuel ratio of the exhaust.

[0021] The electronic control unit 50 has a storage device that holds map data to which various operation control variables, such as target torque, are assigned according to the operating conditions, such as the load, rotation speed, and coolant temperature of the engine 1. During actual operation of the engine 1, the electronic control unit 50 sets the fuel injection amount, fuel injection timing, ignition timing, and the like, by referring to the map data in the storage device based on the operating conditions of the engine 1.

[0022] Next, the contents of the control executed by the electronic control unit 50 will be described with reference to a flowchart.

[0023] 2 is a flow chart showing a basic routine of engine control according to this embodiment of the invention. The electronic control unit 50 executes the control routine shown in FIG.

[0024] In S101, the accelerator operation amount APO, the engine speed N, and the like are input as parameters indicating the operating state of the engine 1. e , cooling water temperature Tw and fuel pressure P f Load etc.

[0025] In S102, as a result of the abnormal torque determination, an abnormality determination flag F trq If the value is 0, the process proceeds to S103, and if the value is 1, the process proceeds to S107. trq is set to 0 at the time of shipment from the manufacturing plant or delivery from the maintenance plant of the vehicle equipped with the engine 1, and the estimated value of the torque actually generated by the engine 1 (hereinafter, the “estimated torque value T act ") and diagnostic torque T dia The abnormality determination flag F is set to 0 or 1 depending on the result of the comparison. trq If changed from 0 to 1, it will remain at 1 even after engine 1 is shut down, and will be rewritten to 0 once any necessary repairs have been completed at the maintenance shop.

[0026] In S103, the accelerator operation amount APO and the engine rotation speed N e Based on this, the command torque T trg Here, the command torque T trg is a command value for the torque generated by the engine 1 (hereinafter, simply referred to as "engine torque T"), which is determined based on the driver's acceleration request (accelerator operation amount APO). trg The calculation is based on the accelerator operation amount APO and the engine speed N e Depending on the command torque T trg This is done by referencing the map data to which the

[0027] In S104, the command torque Ttrg The target value of the intake air volume according to the target intake air volume Q a_t ) is calculated. Target intake air volume Q a_t is the command torque T trg It is set to a larger value as increases.

[0028] In S105, the target intake air volume Q a_t and engine speed N e Based on this, the target value of the throttle opening (target throttle opening TVO _t ) is calculated. Target throttle opening TVO _t The calculation is done by target intake air volume Q a_t Target throttle opening TVO _t engine speed N e The electronic control unit 50 executes the target throttle opening TVO _t A drive signal corresponding to the above is set and output to the electronic throttle device 41.

[0029] In S106, the target intake air volume Q a_t The target value of the fuel injection amount according to f_t ) is calculated. Target fuel injection amount Q f_t is the target intake air volume Q a_t The target fuel injection amount Q obtained in this way is set to a larger value as f_t Correction is made according to the cooling water temperature Tw, etc., to obtain the final target fuel injection amount Q f_t The electronic control unit 50 calculates the target fuel injection amount Q f_t and fuel pressure P f In this embodiment, a drive signal corresponding to the target fuel injection amount Q f_t The target intake air volume Q a_t However, when the target air-fuel ratio is changed according to the operating range of the engine 1, the target fuel injection amount Q f_t The target air-fuel ratio can be taken into consideration when calculating the above.

[0030] In S107 and S108, the accelerator operation amount APO or the command torque Ttrg In other words, the engine torque T is set to a command torque T according to the accelerator operation amount APO. trg Limit the value to less than

[0031] In step S107, the throttle opening TVO of the electronic throttle device 41 is set to the target throttle opening TV O_t A smaller throttle opening limit than TVO _e In this embodiment, the throttle opening limit TVO _e is a fixed value or a calculated value sufficient to allow the vehicle to travel at a low speed toward a repair shop or to escape. The electronic control unit 50 outputs a limit command signal to the electronic throttle device 41. The electronic throttle device 41 receives the limit command signal from the electronic control unit 50 and controls the throttle actuator 301 to move the valve body to the limit throttle opening TVO. _e Here, the "limit command signal" corresponds to a "control signal" that is generated to limit the operation of the engine 1.

[0032] In the S108, the fuel injection amount Q f The target fuel injection amount Q according to the accelerator operation amount APO f_t The fuel injection quantity Q is smaller than f_e and prohibits the vehicle from traveling at a speed exceeding a predetermined speed (for example, 30 km / h).

[0033] In this embodiment, the abnormality determination flag F trq If it is determined that the torque estimation value T act (including the calculation of the abnormality judgment flag F trq Maintain at 1.

[0034] The abnormal torque determination process shown in S102 will be described in detail below.

[0035] 3 is a flow chart showing details of the abnormal torque determination process. The electronic control unit 50 executes the control routine shown in FIG.

[0036] In S201, the intake air amount Qa, the engine speed N e , and the command torque T calculated in S103 trg Load etc.

[0037] In step S202, the torque estimation value T act Calculate the following.

[0038] In S203, the command torque T trg and engine speed N e Based on this, a diagnostic torque T for monitoring an abnormal state of the engine 1 is dia The diagnostic torque T dia The details of the calculation will be described below.

[0039] Figure 4 shows the diagnostic torque T dia FIG. 1 is a block diagram illustrating a configuration for performing the calculation of

[0040] As shown in the figure, the electronic control unit 50 has a torque change determination section 52, a filter processing section 54, and a diagnostic torque calculation section 56.

[0041] The torque change determination unit 52 determines the command torque T trg and the correction command torque T trg2 The previous value of (hereinafter referred to as "previous correction command torque T trg2_(1)") is input and a torque change determination process is executed. The torque change determination process is a process for determining whether the current state is a torque increase, a torque decrease, or a steady state. In this embodiment, a torque increase refers to a state in which the engine torque T is actually in the process of increasing. Furthermore, a torque decrease refers to a state in which the engine torque T is actually in the process of decreasing. Furthermore, a steady state refers to a state in which the engine torque T is maintained unchanged at least over the control section from the previous control section to the current control section.

[0042] 5 is a flowchart showing the details of the torque change determination process. As shown in the figure, in the torque change determination process, the torque change determination unit 52 first trg to previous correction command torque T trg2_(1) to calculate the torque change width ΔT (S3100). Then, the torque change determination unit 52 sets a flag indicating the current state of the engine torque T with reference to the torque change width ΔT. More specifically, the torque change determination unit 52 determines that the current state is torque increasing when the torque change width ΔT is a positive value (Yes in S3110 and S3130). Furthermore, the torque change determination unit 52 determines that the current state is torque decreasing when the torque change width ΔT is a negative value (No in S3110, Yes in S3120, and S3140). Furthermore, the torque change determination unit 52 determines that the current state is steady when the torque change width ΔT is 0 (No in S3110, No in S3120, and S3150). Then, the torque change determination unit 52 outputs a torque state signal S tc and outputs it to the filter processing unit 54.

[0043] 5, it is assumed that the value compared with the torque change width ΔT when determining whether the torque is increasing or decreasing is 0, but a value other than 0 may be used in consideration of various control situations. Also, the value compared with the torque change width ΔT when determining whether the torque is increasing and the value compared with the torque change width ΔT when determining whether the torque is decreasing may be set to different values.

[0044] The filter processing unit 54 filters the torque state signal S generated by the torque change determination unit 52. tc , engine speed N e , and the previous correction command torque T trg2_(1) Refer to the command torque T trg By filtering and correcting the torque command T trg2 Request.

[0045] More specifically, the filter processor 54 of the present embodiment includes a dead time processor 60 and a first-order response lag processor 70 .

[0046] The dead time processor 60 outputs the torque state signal S tc Refer to the command torque T trg and engine speed N e Dead time command torque T trg1 In particular, the dead time processor 60 calculates the engine speed N according to calculation algorithms that are individually set for when the torque is increasing, when the torque is decreasing, and when the engine is in a steady state. e Then, the dead time L is determined and the command torque T trg By adding the dead time L to the trg1 In this embodiment, the dead time L is determined by the command torque T trg It means a filter parameter that indicates the time until the engine torque T starts to respond to the change in trg It is a control parameter indicating a time lag (dead time) from when a change occurs in the torque T until the engine torque T actually starts to change due to the change, and is determined in consideration of the steady-state characteristics of the engine control system that correlate with the torque response performance (such as the operation delay of each actuator and the detection delay of sensors). In particular, the dead time L in this embodiment is determined as a variable value according to the operating state of the engine 1 by performing an appropriate adjustment (correction) according to the operating state of the engine 1, which will be described later, based on a basic value determined based on the steady-state characteristics of the engine control system.

[0047] More specifically, the dead time processing unit 60 of this embodiment has an increasing dead time setting unit 62 , a decreasing dead time setting unit 64 , a dead time selecting unit 66 , and a calculation unit 68 .

[0048] The increase time delay setting unit 62 refers to a predetermined rotation speed-time delay map for torque increase, and sets the engine rotation speed N e On the other hand, the decreasing time delay setting unit 64 determines the time delay L (hereinafter, also referred to as "increasing time delay L1") based on the engine speed N e Then, a dead time L (hereinafter also referred to as "decreasing dead time L2") is determined.

[0049] FIG. 6(a) shows an example of a rotation speed vs. dead time map. As shown in the figure, the rotation speed vs. dead time map of this embodiment is composed of a rotation speed vs. dead time map for torque increase (shown by a solid line) and a rotation speed vs. dead time map for torque decrease (shown by a dashed line). In particular, in both of these maps, the engine rotation speed N e It is determined that the increase and decrease directions of the dead time L are mutually opposite to each other.

[0050] More specifically, the increase time delay L1 defined by the rotation speed-time delay map for torque increase is expressed as follows: e On the other hand, the torque reduction time delay L2 defined in the torque reduction time delay map is set to a larger value as the engine speed N e The higher the torque is, the smaller the value is set. In this way, when the torque is increasing and decreasing, the engine speed N e The reason why the direction of increase / decrease of the dead time L is reversed with respect to the direction of increase / decrease of is as follows.

[0051] Generally, when torque is increased, the engine speed N e The higher the engine speed N, the higher the air density inside the cylinder is required. eAs the torque increases, the required intake volume increases. Therefore, when the engine speed N e In accordance with an increase in the engine speed N e The increase time delay L1 is set so that the higher the torque T, the higher the engine speed N e The higher the intake speed, the higher the intake air speed. Therefore, when the torque is decreasing, the engine speed N e In this embodiment, the torque response is delayed as the engine speed N e The decrease time delay L2 is determined so that the higher the value, the lower the decrease time delay L2.

[0052] Then, the increasing time delay setting unit 62 and the decreasing time delay setting unit 64 output the increasing time delay L1 and the decreasing time delay L2 determined by them, respectively, to a time delay selection unit 66.

[0053] The dead time selection unit 66 selects the torque state signal S tc and outputs either the increasing time delay L1 or the decreasing time delay L2 to the calculation unit 68 as the time delay L to be used in the subsequent calculations. More specifically, the time delay selection unit 66 refers to the torque state signal S tc indicates a torque increase, the torque increase time delay L1 is output as the torque time delay L. Also, the torque time delay selection unit 66 outputs the torque state signal S tc indicates a torque decrease, the torque decrease time delay L2 is output as the torque time delay L. tc indicates a steady state, the previous value of the dead time L is output as it is as the dead time L in the current control cycle.

[0054] The calculation unit 68 calculates the command torque T trg The dead time L output from the dead time selection unit 66 is added to the dead time application command torque T trg1 Request.

[0055] Next, the primary response delay processor 70 will be described. The primary response delay processor 70 processes the torque state signal S tc The time-imposed command torque T trg1 , previous correction command torque T trg2_(1) , and engine speed N e Corrected command torque T trg2 In particular, the primary response delay processor 70 calculates the engine speed N according to calculation algorithms that are individually set for when the torque is increasing, when the torque is decreasing, and when the engine is in a steady state. e The primary delay coefficient K is determined from the above, and the primary delay coefficient K and the previous correction command torque T trg2_(1) Using the dead time command torque T trg1 By applying a predetermined correction calculation to the trg2 Here, the first-order delay coefficient K in this embodiment is determined by the command torque T trg It means a filter parameter that indicates the degree of follow-up of the engine torque T to the change of the command torque T. trg After the change in the engine torque T caused by the change in trg It is a control parameter that indicates the speed at which the torque lag reaches the target torque. The primary delay coefficient K is determined according to the characteristics of the engine control system that correlate with the torque response performance (such as the operation delay of each actuator and the detection delay of sensors). In particular, the primary delay coefficient K in this embodiment is determined as a variable value according to the operating state of the engine 1 by performing an appropriate adjustment (correction) according to the operating state of the engine 1, which will be described later, based on a basic value determined based on the steady-state characteristics of the engine control system.

[0056] In particular, the primary response delay processing unit 70 of this embodiment has an increasing delay coefficient setting unit 72 , a decreasing delay coefficient setting unit 74 , a coefficient selecting unit 76 , and a calculating unit 78 .

[0057] The increase delay coefficient setting unit 72 refers to a predetermined rotation speed-delay coefficient map for torque increase, and determines whether the engine rotation speed N eOn the other hand, the decrease-time delay coefficient setting unit 74 determines a first-order delay coefficient K (hereinafter also referred to as "increase-time delay coefficient K1") based on the engine speed N e The first-order delay coefficient K (hereinafter also referred to as "decreasing delay coefficient K2") is determined based on the above.

[0058] FIG. 6(b) shows an example of the rotation speed-delay coefficient map. As shown in the figure, the rotation speed-delay coefficient map of this embodiment is composed of a delay coefficient map for torque increase (indicated by a solid line) and a delay coefficient map for torque decrease (indicated by a dashed line). In particular, in both of these maps, the engine rotation speed N e The increase / decrease direction of the first-order lag coefficient K is set to be opposite to the increase / decrease direction of the first-order lag coefficient K.

[0059] More specifically, the increase delay coefficient K1 defined in the rotation speed-delay coefficient map for torque increase is e On the other hand, the torque reduction delay coefficient K2, which is specified in the engine speed-delay coefficient map for torque reduction, is set to a smaller value as the engine speed N e It is set to a larger value as

[0060] In this way, when the torque increases and decreases, the engine speed N e The reason why the direction of increase / decrease of the first-order delay coefficient K is reversed with respect to the direction of increase / decrease of the engine speed N e This is the same as the reason why the direction of increase / decrease of the dead time L is reversed with respect to the direction of increase / decrease of

[0061] In other words, in the rotation speed-delay coefficient map for torque increase, the engine rotation speed N e Considering that the response of the engine torque T becomes slower with an increase in the engine speed N e The delay coefficient K1 during torque increase is set to a lower value as the engine speed N eConsidering that the response of the engine torque T becomes faster with the increase of the engine speed N e The decrease delay coefficient K2 is set to a higher value as the value increases.

[0062] Then, the increase delay coefficient setting section 72 and the decrease delay coefficient setting section 74 output the increase delay coefficient K1 and the decrease delay coefficient K2 that they have determined, respectively, to the coefficient selection section .

[0063] The coefficient selection unit 76 selects the torque state signal S tc , and outputs either the increasing delay coefficient K1 or the decreasing delay coefficient K2 to the calculation unit 78 as the first-order delay coefficient K to be used in the subsequent calculations. tc indicates a torque increase, the coefficient selection unit 76 outputs the increase delay coefficient K1 as the first-order delay coefficient K. tc indicates a torque decrease, the coefficient selection unit 76 outputs the decrease delay coefficient K2 as the first-order delay coefficient K. tc indicates a steady state, the previous value of the first-order lag coefficient K is output as it is as the first-order lag coefficient K in the current control cycle.

[0064] The calculation unit 78 calculates the dead time imparting command torque T trg1 The value obtained by multiplying by the primary delay coefficient K is inverted and "1" is added to obtain the previous correction command torque T trg2_(1) The corrected command torque T trg2 Request.

[0065] In addition, the command torque T trg Corrected command torque T trg2 The calculation for obtaining can be expressed by the following equation (1).

[0066]

number

[0067] Returning to FIG. 4, the diagnostic torque calculation unit 56 calculates the corrected command torque T trg2 A predetermined threshold value ΔT is added to the torque for diagnosis T dia Here, the diagnostic torque T dia is the command torque T trg Therefore, the threshold value ΔT is determined as the upper limit of the allowable torque range in which the torque state can be determined to be normal based on the relationship between the upper limit and the corrected command torque T trg2 The difference between the corrected torque command T trg2 It is also possible to adopt a configuration in which the threshold value ΔT itself is set as the upper limit value of the allowable torque range. dia Corrected command torque T trg2 It is also possible to adopt a configuration in which the value is the same as that of the

[0068] FIG. 7 shows the above-mentioned diagnostic torque T dia 1 is a flowchart showing the overall process flow in the calculation of the diagnostic torque T dia In the calculation of the torque increase (Yes in S2031), the command torque T is calculated using the increase time delay L1 and the increase delay coefficient K1. trg is filtered to obtain the corrected torque command T trg2 (S2033 and S2036), and the corrected command torque T trg2 to diagnostic torque T dia (S2037).

[0069] On the other hand, when the torque is decreasing (No in S2031 and Yes in S2032), the command torque T trg is filtered to obtain the corrected torque command T trg2 (S2034 and S2036), and the corrected command torque T trg2 to diagnostic torque T dia (S2037).

[0070] Furthermore, during steady state (No in S2031 and No in S2032), the dead time L and the first-order delay coefficient K are held at the previous values, and the corrected command torque T trg2 (S2035 and S2036), and the corrected command torque T trg2 to diagnostic torque T dia In addition, in the steady state, the previous correction command torque T trg2_(1) and command torque T trg Since these match, even after filtering by the filter processing unit 54, the command torque T trg is output to the diagnostic torque calculation unit 56 as is without being substantially corrected. Therefore, if the above-mentioned calculation logic is used, the command torque T trg Even during steady state operation where correction for the torque T is not required, the torque T can be appropriately calculated in the same manner as when the calculation logic for the correction is not adopted. dia can be sought.

[0071] Returning to FIG. 3, in the process of S203, the diagnostic torque T dia After the torque estimation value T act is the diagnostic torque T dia It is determined whether the torque estimate T act is the diagnostic torque T dia If it is equal to or less than the torque limit, proceed to S205 and dia If it exceeds this, proceed to S206.

[0072] In S205, the engine torque T is the diagnostic torque T dia The abnormality determination flag F trq Set to 0.

[0073] On the other hand, in S206, it is determined that the engine torque T is excessively large and some kind of malfunction has occurred in the engine control, and the abnormality determination flag F trq is set to 1. In order to more reliably prevent erroneous detection of an abnormal state, the torque estimation value T act is the diagnostic torque T diaIf the judgment exceeds the limit multiple times, the abnormality judgment flag F trq is set to 1, otherwise the abnormality determination flag F trq A configuration in which the signal level is kept at 0 may be adopted.

[0074] According to the engine diagnostic method of the present embodiment described above, the command torque T trg Change in engine speed N e The command torque T is calculated by filtering using filter parameters that are appropriately determined according to the level of trg After correcting the command torque T trg (corrected command torque T trg2 ) to diagnostic torque T dia can be determined.

[0075] In this embodiment, the engine speed N e In the above example, the filter parameters (dead time L and first-order lag coefficient K) are calculated based on the engine speed N at the time of torque increase and torque decrease. However, the calculation logic for determining appropriate filter parameters by referring to the operating state of the engine 1 is not limited to the above example. For example, as described below, e Instead of or in addition to the map that specifies the relationship between the engine torque T and the filter parameter, a map that specifies the relationship between the engine torque T and the filter parameter is prepared, and a control parameter that indicates the engine torque T (specifically, a command torque T trg or torque estimate T act ) may be used to determine the filter parameters.

[0076] Fig. 8 shows an example of a map that defines the relationship between engine torque T and filter parameters (dead time L and first-order lag coefficient K). In particular, as shown in Fig. 8(a), a torque-dead time map in which a map for torque increase (shown by a solid line) and a map for torque decrease (shown by a dashed line) are set separately may be used. Also, as shown in Fig. 8(b), a torque-lag coefficient map in which a map for torque increase (shown by a solid line) and a map for torque decrease (shown by a dashed line) are set separately may be used.

[0077] Furthermore, in this embodiment, in order to estimate whether the current state is a torque increase or a torque decrease, a torque change width δT (=T trg -T trg2_(1) ) is positive or negative, and the operating state of the engine 1 (engine speed N e In the above example, the filter parameters are determined from the engine rotation speed N (or engine torque T). However, the present invention is not limited to this. A map that determines the relationship between the operating state of the engine 1 and the filter parameters may be adjusted by referring to the magnitude of the torque change width ΔT. For example, for the rotation speed-dead time map for torque increase shown in FIG. 6(a), the larger the torque change width ΔT (>0) is (the higher the torque increase rate is), the larger the engine rotation speed N e The time wastage L (time wastage L1 during increase) for the torque reduction may be set to a larger value (so that the slope of the solid line graph shown in the figure becomes steeper). In addition, for the engine speed N e The filter parameters may be determined so that the dead time L (decreasing dead time L2) for the engine 1 has a small value (so that the slope of the dashed line graph shown in the figure becomes smaller). The rotation speed-delay coefficient map may also be adjusted according to the torque change width ΔT from a similar perspective. This allows appropriate filter parameters to be determined while taking into account the degree of change in the operating state of the engine 1.

[0078] Fig. 9 is an explanatory diagram showing the operation of the electronic control unit 50 with respect to abnormal torque judgment. In particular, Fig. 9(a) shows the control result by the engine diagnosis method of the example (the above embodiment), and Fig. 9(b) shows the control result by the engine diagnosis method of the comparative example. Note that the comparative example differs from the example in that the dead time L and the first-order lag coefficient K, which are filter parameters, are fixed values ​​that do not depend on torque increase or decrease, but the engine diagnosis method is assumed to be the same in other respects as the example.

[0079] First, in the control of the comparative example shown in FIG. 9(b), the command torque T trg In the section (time t1 to t2) where the change width of the command torque T exceeds 0, it is determined that the torque is increasing. trg is filtered to obtain the corrected command torque T trg2 Then, the corrected command torque T obtained by the filtering process is trg2 is the actual engine torque T (≒ estimated torque T act ) along the profile of the command torque T trg Therefore, the correction command torque T trg2 The diagnostic torque T obtained by adding the threshold ΔT to dia Generally, the torque estimate T act Therefore, the engine torque T is judged to be abnormal (the estimated torque T act is the diagnostic torque T dia The judgment that the amount exceeds the limit will also be made appropriately.

[0080] On the other hand, the command torque T trg In the section (time t3 to t4) where the change width of is less than 0, it is determined that the torque is decreasing. Here, in the control of the comparative example, even in the section where it is determined that the torque is decreasing, the corrected command torque T is calculated by filtering using a filter in which the same values ​​of dead time L and first-order delay coefficient K as those in the case of increasing torque are specified. trg2However, the torque response characteristics in the engine control system during torque reduction are different from those during torque increase. For this reason, the corrected command torque T trg2 The diagnostic torque T obtained from dia is the actual engine torque T (estimated torque T act ) is out of sync with the changing behavior of

[0081] More specifically, as shown by the dashed-dotted line graph, the solid line graph, and the dotted line graph in FIG. 9B, after time t4, the torque estimation value T act Compared to the diagnostic torque T dia decreases more quickly, and the diagnostic torque T dia is the torque estimate T act As a result, in this section, the torque estimation value T act is the diagnostic torque T dia (No in S204 in FIG. 3), which may lead to an erroneous determination of abnormal torque.

[0082] In contrast, in the control of the embodiment shown in FIG. 9(a), a filter is adopted in which the filter parameters (dead time L and first-order lag coefficient K) are individually adjusted in the section determined as torque increasing (time t1 to t2) and the section determined as torque decreasing (time t3 to t4) taking into consideration the difference in the torque response characteristics in each scene. Therefore, the corrected command torque T trg2 The diagnostic torque T obtained from dia The command torque T trg The response behavior of the actual engine torque T to the change in act Therefore, it is possible to suppress the occurrence of the above-mentioned erroneous abnormal torque determination. In other words, it is possible to maintain the diagnostic accuracy of the engine 1 regardless of the operating state of the engine 1 (whether the torque is increasing or decreasing).

[0083] In the control of the embodiment shown in FIG. 9(a), the command torque T trg and the corrected command torque Ttrg2 (Command torque T trg The section where the difference between the command torque T and the torque change width ΔT (i.e., the value obtained by filtering the command torque T) exceeds 0 is determined as the torque increase period (time t1 to t2). trg and the corrected command torque T trg2 The section where the difference falls below 0 is determined to be a torque decreasing period (time t3 to t4). This makes it possible to more appropriately distinguish between increasing and decreasing engine torque T periods where the response characteristics differ, and to switch the filter, thereby further improving the accuracy of diagnosis of the engine 1.

[0084] The configuration of the engine diagnosis method according to this embodiment and the effects obtained thereby will be described below.

[0085] In this embodiment, the command torque T trg The corrected command torque T is obtained by correcting the actual output engine torque T with a correction amount according to the response characteristics. trg2 Calculate the corrected command torque T trg2 The diagnostic torque T is determined based on dia and the torque estimate T act By comparing these, an engine diagnosis method is provided for diagnosing the state of the engine torque T. In this engine diagnosis method, the operating state of the engine 1 is referred to to adjust the correction amount.

[0086] This allows the command torque T to be calculated while taking into account the difference in the response characteristics of the engine torque T according to the change in the operating state of the engine 1. trg to diagnostic torque T dia That is, the diagnostic torque T dia This makes it possible to more reliably reflect the effect of the change in the response characteristic according to the operating state of the engine 1 in the calculation of (a). Therefore, it is possible to ensure the accuracy of diagnosis of the state of the engine torque T, regardless of the operating state of the engine 1.

[0087] In particular, in this embodiment, the operating state of the engine 1 is determined by the engine torque T, the amount of change in the engine torque T (torque change width ΔT), and the engine speed N e And the command torque T trg The corrected torque command T is obtained by applying a filter defined by the filter parameters (L, K) that indicate the above response characteristics to the trg2 Furthermore, the filter parameters (L, K) are calculated based on the engine torque T, the torque change width δT, and the engine speed N e The correction amount is adjusted by setting the variable value according to at least one of the above.

[0088] This results in a command torque T trg Corrected command torque T trg2 The calculation for obtaining the command torque T trg A specific calculation logic for adjusting the above-mentioned correction amount for can be realized by a simple method of making filter parameters variable according to each parameter indicating the operating state of the engine 1.

[0089] Furthermore, in this embodiment, as the filter parameters (L, K), a first filter parameter (L1, K1) determined in accordance with the response characteristics when the engine torque T increases, and a second filter parameter (L2, K2) determined in accordance with the response characteristics when the engine torque T decreases are set (increasing time dead time setting unit 62, decreasing time dead time setting unit 64, increasing time delay coefficient setting unit 72, and decreasing time delay coefficient setting unit 74 in FIG. 4).

[0090] Also, by referring to the torque change width ΔT, it is determined whether the current state is an increase (torque increase) or decrease (torque decrease) of the engine torque T (torque change determination unit 52). When the torque is increasing (Yes in S2031 in FIG. 7), a filter defined by the first filter parameters (L1, K1) is applied to obtain the corrected command torque T trg2On the other hand, when the torque is decreasing (No in S2031), the correction command torque T is calculated by applying a filter defined by the second filter parameters (L2, K2). trg2 is calculated (S2034 and S2036).

[0091] This allows the filter to be determined individually in consideration of the difference in response characteristics when the engine torque T is increasing and decreasing, where the response characteristics are different from each other. Therefore, in both cases of torque increase and torque decrease, the command torque T trg The diagnostic torque T is more in line with the response behavior of the actual engine torque T to the change in dia (corrected command torque T trg2 ) is realized.

[0092] In particular, when the engine diagnosis method of the present embodiment is applied to the engine 1 mounted as the driving source of the vehicle described above, it is possible to ensure diagnostic accuracy for the engine 1 in both typical vehicle acceleration scenes as torque increase and typical vehicle deceleration scenes as torque decrease. More specifically, in the engine 1 used as a driving source of the vehicle, it is assumed that the engine torque T changes frequently during operation of the engine 1, such as requests for acceleration or deceleration of the vehicle in response to accelerator operation by the driver. In contrast, the calculation logic employed in the engine diagnosis method described above can ensure diagnostic accuracy for the state of the engine torque T even in such scenes where the engine torque T changes frequently.

[0093] Furthermore, in this embodiment, the filter parameters (L, K) are trg The dead time L indicates the time until the engine torque T starts responding to the change in trgand a first-order lag coefficient K indicating the high degree of tracking ability to the input signal. The dead time L (increasing dead time L1) and the first-order lag coefficient K (increasing lag coefficient K1) in the first filter parameters (L1, K1) and the dead time L (decreasing dead time L2) and the first-order lag coefficient K (decreasing lag coefficient K2) in the second filter parameters (L2, K2) are set individually.

[0094] This realizes a more specific calculation logic for determining the filter parameters (L, K) that reflect the difference in the response characteristics of the engine torque T when the torque increases and when the torque decreases.

[0095] In particular, in this embodiment, the increasing time delay L1 in the first filter parameter is set to the engine speed N e The increase delay coefficient K1 in the first filter parameter is set to a larger value as the engine speed N increases and / or the engine torque T decreases (see the solid line graphs in FIG. 6(a) and FIG. 8(a)). e and / or the engine torque T is smaller, the lower the set value (see the dashed line graphs in FIG. 6(a) and FIG. 8(a)).

[0096] This allows the engine speed N e Alternatively, a more specific calculation logic for determining the first filter parameters (L1, K1) that more appropriately reflects the difference in the torque response characteristics of the engine control system depending on the magnitude of the engine torque T is realized.

[0097] In this embodiment, the decreasing time delay L2 in the second filter parameter is set to the engine speed N e The higher the engine speed N and / or the smaller the engine torque T, the smaller the set value (see the solid line graphs in FIG. 6(b) and FIG. 8(b)). e and / or the engine torque T is smaller, the larger the set value is (see the dashed line graphs in FIG. 6(b) and FIG. 8(b)).

[0098] This reduces the engine speed N e Alternatively, a more specific calculation logic for determining the second filter parameters (L1, K1) that more appropriately reflects the difference in the torque response characteristics of the engine control system depending on the magnitude of the engine torque T is realized.

[0099] Furthermore, in this embodiment, the correction command torque T trg2 Past values ​​of (especially the previous correction command torque T trg2_(1) ) is used to determine whether the current torque change state is an increase (torque increase) or a decrease (torque decrease). In particular, in this engine diagnosis method, when it is determined that the torque is increasing, the command torque T trg The first filter (62, 72) is applied to the corrected command torque T trg2 In particular, the first filter is defined by the first filter parameters (L1, K1) determined according to the response characteristics when the engine torque T increases. On the other hand, when it is determined that the torque is decreasing, the command torque T trg The second filter (64, 74) is applied to the corrected command torque T trg2 In particular, the second filter is defined by second filter parameters (L2, K2) determined according to the response characteristics when the engine torque T increases.

[0100] This makes it possible to accurately detect scenes in which the engine torque T increases and scenes in which it decreases, and to realize specific control logic for switching between the first filter and the second filter, which are set taking into account the differences in the torque response characteristics for each scene.

[0101] In addition, in this embodiment, when the torque change width ΔT is equal to a predetermined value (0 in this embodiment), the filter set during the previous control is maintained and the corrected command torque T trg2 Calculate the following.

[0102] This allows accurate detection of a scene (steady state) in which the engine torque T does not increase or decrease, and during the steady state, the filter selected for the previous behavior (increase or decrease) of the engine torque T can be maintained. Therefore, during the steady state, the correction amount by the filtering process is substantially set to 0 (command torque T trg = Corrected command torque T trg2 Therefore, the filter switching according to the increase and decrease of the engine torque T can be realized by a simple control logic, while the filter switching according to the increase and decrease of the engine torque T can be realized in the steady state where the engine torque T does not change, that is, in the steady state where the command torque T trg In a scene where correction by filtering processing is not required for the corrected command torque T trg2 The command torque T trg The final diagnostic torque T obtained by matching dia This makes it possible to more reliably prevent errors from occurring in the calculation.

[0103] Furthermore, in this embodiment, an electronic control unit 50 is provided that functions as an engine diagnostic device suitable for performing the above-mentioned engine diagnostic method. trg The corrected command torque T trg2 Calculate the corrected command torque T trg2 The diagnostic torque T is determined based on dia and the torque estimate T act By comparing these, the state of the engine torque T is diagnosed. In particular, the electronic control unit 50 refers to the operating state of the engine 1 and adjusts the above correction amount.

[0104] In addition, the electronic control unit 50 of this embodiment calculates the correction command torque T trg2 Past value of previous correction command torque T trg2_(1) ) functioning as an engine diagnostic device that determines whether the current state is an increase (torque increase) or a decrease (torque decrease) of the engine torque T. In particular, when it is determined that the torque is increasing, the electronic control unit 50 sets the command torque Ttrg The first filter (62, 72) is applied to the corrected command torque T trg2 The first filter is defined by first filter parameters (L1, K1) determined according to the response characteristics when the engine torque T increases. On the other hand, when the electronic control unit 50 determines that the torque is decreasing, it calculates the command torque T trg The second filter (64, 74) is applied to the corrected command torque T trg2 The second filter is defined by second filter parameters (L2, K2) determined according to the response characteristics when the engine torque T increases.

[0105] [Second embodiment] The second embodiment will be described below, in which the same elements as those in the first embodiment are given the same reference numerals and the description thereof will be omitted.

[0106] FIG. 10 shows the diagnostic torque T dia As shown in the figure, in this embodiment, the torque change determination unit 52 calculates a plurality of corrected command torques T trg2 Past value of T trg2_(n) Only the command torque T trg In particular, the torque change determination unit 52 executes the torque change determination process without using a predetermined change width initial value, a past value T trg2_(n) (Previous correction command torque T trg2_(1) ), and the past value T from two periods ago trg2_(n) (The previous correction command torque T trg2_(2) ) to determine the current torque change state.

[0107] 11 is a flowchart showing details of the torque change determination process in this embodiment. As shown in the figure, in this embodiment, the torque change determination unit 52 stores a past value, that is, a previous corrected command torque T trg2_(1) and the previous correction command torque T trg2_(2) It is determined whether or not the file exists (S3200).

[0108] If the result of the above determination is positive, the torque change determination unit 52 determines the previous corrected command torque T trg2_(1) From the previous correction command torque T trg2_(2) To calculate the torque change width ΔT (S3210), on the other hand, if the above determination result is negative, torque change determination unit 52 reads out a predetermined change width initial value (for example, 0) from the storage area and sets the torque change width ΔT to the change width initial value (S3220).

[0109] Furthermore, the torque change determination unit 52 refers to the calculated torque change width ΔT and generates the torque state signal S tc (S3230 to S3270) and outputs this to the filter processing unit 54.

[0110] Fig. 12 is an explanatory diagram showing the operation of the electronic control unit 50 regarding abnormal torque determination according to this embodiment. In particular, Fig. 12(a) shows the control result according to the engine diagnosis method of this embodiment, and Fig. 12(b) shows the control result according to the engine diagnosis method of the first embodiment.

[0111] As can be seen by comparing FIG. 12(a) and FIG. 12(b), in this embodiment, the actual engine torque T (≈ the estimated torque value T act ) increase and decrease scenes can be detected with higher accuracy to switch between the first filter and the second filter, thereby improving the accuracy of diagnosis of the engine torque T.

[0112] The configuration of the engine diagnosis method according to this embodiment and the effects obtained thereby will be described below.

[0113] In the engine diagnosis method according to the present embodiment, the correction command torque T trg2 The torque change width δT (=T trg2_(1) -T trg2_(2)If the torque change width ΔT is larger than a predetermined value, it is determined that the current state is when the engine torque T is increasing, and if the torque change width ΔT is smaller than the predetermined value, it is determined that the current state is when the engine torque T is decreasing.

[0114] This allows the command torque T trg The behavior of the engine torque T is more realistic (the torque estimate T act The filtered value that matches the behavior of the torque command T trg2 Therefore, the first filter and the second filter can be switched more appropriately, and the accuracy of diagnosis of the engine torque T can be further improved.

[0115] Furthermore, the correction command torque T trg2 If there is no past value of , a predetermined initial value of the variation width is referenced to determine whether the current state is one in which the engine torque T is increasing or decreasing.

[0116] This results in a correction command torque T trg2 The torque change determination process can be executed even during the initial calculation of the torque change amount.

[0117] Although the embodiments of the present invention have been described above, the above-described embodiments merely illustrate some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above-described embodiments.

[0118] For example, in the above embodiment, an example has been described in which the engine diagnosis method is applied to the engine 1 mounted on a vehicle as a driving source for traveling. However, the present invention is not limited to this, and the engine diagnosis method according to the present invention may be applied when the engine 1 is used for other purposes. For example, when the engine 1 is used only as a drive device for a generator in an electric vehicle (when the engine 1 does not function as a driving source for traveling), and a command torque T trg When changing the command torque Ttrg to diagnostic torque T dia (corrected command torque T trg2 It is also possible to employ a configuration in which the correction amount (particularly the above-mentioned filter parameter) for determining (a) is variable according to the operating state of the engine 1. Furthermore, the engine diagnosis method according to the present invention may be applied to applications other than those mounted on a vehicle, in which it is required to change the operating state at a certain frequency while the engine 1 is in operation.

[0119] Furthermore, the filter parameters are not limited to the dead time L and the first-order lag coefficient K. In other words, any parameter that can indicate the response characteristics of the engine torque T can be used as the filter parameters in addition to these, depending on the type of filter to be used. In addition, the command torque T based on the operating state of the engine 1 can be used as the filter parameters. trg Corrected command torque T trg2 The specific manner of the calculation is not limited to the filter processing, and any calculation logic capable of realizing the same function may be adopted. For example, the relationship between the assumed operating state of the engine 1 and the correction amount appropriate for the operating state is experimentally investigated and mapped, and the command torque T trg Corrected command torque T trg2 It is also possible to adopt a configuration in which the following is calculated. [Explanation of symbols]

[0120] 1 engine, 50 electronic control unit, 52 torque change determination section, 54 filter processing section, 60 dead time processing section, 62 increasing dead time setting section, 64 decreasing dead time setting section, 66 dead time selection section, 68 calculation section, 70 primary response delay processing section, 72 increasing delay coefficient setting section, 74 decreasing delay coefficient setting section, 76 coefficient selection section, 78 calculation section, 80 diagnostic torque calculation section

Claims

1. A corrected command torque is calculated by correcting the engine command torque with a correction amount according to the response characteristics of the engine torque that is actually output; An engine diagnosis method for diagnosing a state of the engine torque by comparing a diagnostic torque determined based on the corrected command torque with a torque estimate value, comprising: determining whether the engine torque is currently increasing or decreasing based on a past value of the corrected command torque; When it is determined that the torque is increasing, a first filter is applied to the torque command to calculate the corrected torque command; the first filter is defined by a first filter parameter determined in accordance with the response characteristic when the engine torque increases, When it is determined that the torque is decreasing, a second filter is applied to the torque command to calculate the corrected torque command; the second filter is defined by a second filter parameter determined in accordance with the response characteristic when the engine torque decreases; Engine diagnostic methods.

2. 2. The engine diagnostic method according to claim 1, calculating a change width of the corrected command torque per predetermined control period based on the past value; If the change amount is greater than a predetermined value, it is determined that the current state is a time when the engine torque is increasing, If the change amount is smaller than the predetermined value, it is determined that the current state is a time when the engine torque is decreasing. Engine diagnostic methods.

3. 3. The engine diagnostic method according to claim 2, If the past value does not exist, a predetermined initial value of the change width is referenced to determine whether the current state is an increase or decrease of the engine torque. Engine diagnostic methods.

4. 3. The engine diagnostic method according to claim 2, When the change width is equal to the predetermined value, the filter set during the previous control is maintained to calculate the corrected command torque. Engine diagnostic methods.

5. 2. The engine diagnostic method according to claim 1, the first filter parameter and the second filter parameter each include a dead time indicating a time until the engine torque starts to respond in response to a change in the command torque, and a first-order lag coefficient indicating a degree of follow-up to the command torque after the engine torque starts to respond, The dead time and the first-order lag coefficient in the first filter parameter and the dead time and the first-order lag coefficient in the second filter parameter are set separately. Engine diagnostic methods.

6. 6. The engine diagnostic method according to claim 5, The dead time in the first filter parameter is set to be larger as the engine rotation speed is higher and / or the engine torque is smaller, The first-order lag coefficient in the first filter parameter is set to be smaller as the engine rotation speed is higher and / or the engine torque is smaller. Engine diagnostic methods.

7. 6. The engine diagnostic method according to claim 5, The waste time in the second filter parameter is set to be smaller as the engine rotation speed is higher and / or the engine torque is smaller, The first-order lag coefficient in the second filter parameter is set to be larger as the engine rotation speed is higher and / or the engine torque is smaller. Engine diagnostic methods.

8. A corrected command torque is calculated by correcting the engine command torque with a correction amount according to the response characteristics of the engine torque that is actually output; An engine diagnostic device that diagnoses a state of the engine torque by comparing a diagnostic torque determined based on the corrected command torque with a torque estimate value, determining whether the engine torque is currently increasing or decreasing based on a past value of the corrected command torque; When it is determined that the torque is increasing, a first filter is applied to the torque command to calculate the corrected torque command; the first filter is defined by a first filter parameter determined in accordance with the response characteristic when the engine torque increases, When it is determined that the torque is decreasing, a second filter is applied to the torque command to calculate the corrected torque command; the second filter is defined by a second filter parameter determined in accordance with the response characteristic when the engine torque decreases; Engine diagnostic equipment.

Images