JP4422563B2 - Engine combustion state diagnostic device - Google Patents

Description

  The present invention relates to an engine combustion state diagnosing device, and more particularly to an engine combustion state diagnosing device that can accurately determine the presence or absence of abnormal combustion (misfire) without being affected by disturbance.

  2. Description of the Related Art Conventionally, a technique is known in which a combustion state is detected by measuring the number of revolutions using the relationship between torque generated by engine combustion and the number of revolutions, and indirectly detecting misfire (for example, the following patents) Reference 1 etc.). In this technique, the rotational speed of the engine is detected by at least two ignitions in one ignition cycle from the previous ignition to the current ignition, and the rotational speed fluctuation value of the engine in the one ignition cycle is determined by the difference in the rotational speeds. Is calculated, and the rotational speed fluctuation value obtained sequentially is statistically calculated, and the result of the calculation is used to diagnose the combustion state of the engine.

JP 58-51243 A (pages 1-8, FIGS. 1-8)

  However, as described above, the diagnostic technique using the rotational speed fluctuation has a relatively steady diagnostic area because the necessary diagnostic accuracy cannot be ensured at the time of acceleration / deceleration in which the rotational speed fluctuation occurs even in the normal combustion state. It will be limited to the area.

  On the other hand, recently, there is a direction in which the diagnosis area is widened according to the law.For example, even during acceleration / deceleration from the idle state to the off-idle state, and from the off-idle to the idle state, which has been conventionally recognized as being outside the diagnosis area, Since it is necessary to carry out a diagnosis, it is necessary to construct a logic capable of ensuring a necessary diagnosis accuracy even during acceleration / deceleration in the method using the rotational speed fluctuation.

  In other words, in the conventional technology, the rotational speed greatly fluctuates due to the effects of vehicle reverberation caused by torque fluctuations that occur during acceleration / deceleration, etc. from the idle state to off-idle and from off-idle to idle state. There is a risk of accidental misjudgment.

  The present invention has been made to solve the conventional problems as described above, and the object of the present invention is to accurately perform abnormal combustion (without being affected by disturbances such as vehicle reverberation even during acceleration / deceleration). An object of the present invention is to provide an engine combustion state diagnostic apparatus capable of determining the presence or absence of misfire.

  In order to achieve the above object, a combustion state diagnostic apparatus for an engine according to the present invention comprises a required time measuring means for measuring a required time required for the crankshaft to rotate a predetermined angle, and a first combustion state from the required time. A first parameter calculating means for calculating a reverberation parameter; a second parameter calculating means for calculating a second combustion state reverberation parameter from the required time; the first combustion state reverberation parameter; and the second combustion state. Reverberation determination means for determining whether or not the combustion state is a reverberation state based on the reverberation parameter; and combustion state determination means for determining the presence or absence of abnormal combustion such as misfire based on the determination result of the reverberation determination means; It is comprised and comprises.

  The first and second parameter calculation means preferably extract a crankshaft two-rotation period signal.

  Preferably, the first combustion state reverberation parameter calculated by the first parameter calculation means preferably rotates two crankshafts with respect to the second combustion state reverberation parameter calculated by the second parameter calculation means. The components other than the components have different strengths.

  Preferably, the reverberation determination means performs combustion when the ratio or difference between the first combustion state reverberation parameter and the second combustion state reverberation parameter is equal to or less than a first determination value or equal to or greater than a second determination value. A state reverberation state is determined.

  The first determination value and the second determination value are preferably switched according to the operating state of the idle switch or the throttle opening.

  The first determination value and the second determination value are preferably functions of the engine load and the engine water temperature.

  Preferably, the reverberation determination means performs the determination when the engine speed is equal to or lower than a predetermined value, and more preferably, when the engine speed is equal to or higher than the predetermined value and the vehicle speed is equal to or higher than the predetermined value. To be done.

  In another preferred aspect, the apparatus includes combustion state parameter calculating means for calculating a combustion state parameter, and the combustion state determining means determines the presence or absence of abnormal combustion based on the combustion state parameter and the determination result of the reverberation determining means. To be done.

  The combustion state parameter is preferably a difference between the required times at the time of current ignition and the time of previous ignition.

  Preferably, the combustion state determination means determines that abnormal combustion has occurred when the combustion state parameter is greater than or equal to a predetermined determination value and the reverberation determination means determines that the combustion state reverberation state is not present. Is done.

  In the combustion state determination means, the predetermined determination value compared with the combustion state parameter is preferably a function of engine speed and / or engine load.

  In a preferred aspect of the combustion state diagnostic apparatus according to the present invention configured as described above, the first combustion state reverberation parameter and the second combustion state reverberation parameter are, for example, parameters for extracting a crankshaft two-rotation component. It is. The first combustion state reverberation parameter and the second combustion state reverberation parameter show the same value in the band of the crankshaft two-rotation component, but show different values in the band other than the crankshaft two-rotation component.

  On the other hand, when misfire occurs, the first combustion state reverberation parameter is equal to the second combustion state reverberation parameter because there is a characteristic of the crankshaft two-rotation component. That is, if the combustion state parameter exceeds a predetermined determination value, and the first combustion state reverberation parameter and the second combustion state reverberation parameter show substantially the same value, it is determined that the misfire has occurred. Further, when a deviation greater than or equal to a predetermined value occurs between the first combustion state reverberation parameter and the second combustion state reverberation parameter, even if the combustion state parameter exceeds a predetermined determination value, misfire may be caused by something other than misfire. Is not judged.

  In the combustion state diagnosis apparatus according to the present invention, misfire and vehicle reverberation can be distinguished and determined even in an operation mode in which fluctuations in rotational speed occur due to the effect of vehicle reverberation even in a normal combustion state such as during acceleration and deceleration. Misjudgments can be eliminated, so that the misfire diagnosis area can be expanded to the entire operation area including acceleration and deceleration, and as a result, the regulatory requirements can be satisfied.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an embodiment of a combustion state diagnostic apparatus according to the present invention together with an in-vehicle engine to which the apparatus is applied.

  In FIG. 1, the engine 10 is provided with an ignition device 201 in its combustion chamber 214, and the flow rate of air taken in from an air cleaner 200 provided at the tip of the intake passage 220 is adjusted by a throttle valve 213. Thereafter, the flow rate passing through the air flow sensor 204 is measured and mixed with fuel injected at a predetermined angle from the fuel injection valve 202 to burn each cylinder (# 1, # 2, # 3, # 4). Supplied to the chamber 214. The exhaust passage 230 is provided with an air-fuel ratio sensor 205, a three-way catalyst 206, and the like. The exhaust gas is purified by the three-way catalyst 206 and then discharged to the atmosphere.

  On the other hand, after the fuel in the fuel tank 209 is sucked and pressurized by the fuel pump 210, it is guided to the fuel inlet of the fuel injection valve 202 through the fuel piping system 212 provided with the pressure regulator 211, and excess fuel. Is returned to the fuel tank 209. In this embodiment, an in-line four-cylinder engine will be described as an example, but it is needless to say that the present invention is not limited to this.

  In addition to the above configuration, in order to control the ignition timing by the ignition device 201 and the fuel injection amount (air-fuel ratio) by the fuel injection valve 202, a control unit 100 having a well-known configuration is provided. Yes. In the control unit 100, a signal corresponding to the intake air amount (Qa) detected by the air flow sensor 204, a signal corresponding to the rotational speed (engine rotational speed Ne) of the crankshaft 208 detected by the rotational speed sensor 203, A signal or the like corresponding to the air-fuel ratio detected by the air-fuel ratio sensor 205 is supplied, and the control unit 100 performs ignition timing control, fuel injection (air-fuel ratio) control, and the like based on those signals, and diagnoses the combustion state. (Determination of the presence or absence of abnormal combustion such as misfire) is performed.

  FIG. 2 is a functional block diagram showing the combustion state diagnosis contents executed by the control unit 100. The required time measuring means 101 for measuring the time required for the crankshaft 208 to rotate at a predetermined angle, and the combustion state parameters are shown. Combustion state parameter calculating means 102 for calculating, first parameter calculating means 103 for calculating a first combustion state reverberation (effect remaining as a result of combustion) parameter from the required time, and a second combustion state from the required time A second parameter calculating means 104 for calculating a reverberation parameter; and a reverberation determining means for determining whether or not the combustion state is a reverberation state based on the first combustion state reverberation parameter and the second combustion state reverberation parameter. 105, and abnormal combustion such as misfire based on the combustion state parameter and the determination result of the reverberation determination means 105. It comprises a combustion state determining means 106 determines the presence or absence of.

  Here, the combustion state diagnosis of the present embodiment will be described from the premise facts and considerations based on the facts.

  FIG. 3 is a graph showing changes in the rotational speed with respect to the crank angle of the engine. This is the waveform when misfire occurs in the third cylinder # 3, and the broken line is when the combustion state is normal. In FIG. 3, the rotation speed measurement section [hereinafter referred to as window width (predetermined crank angle)] for each cylinder (# 1, # 2, # 3, # 4) will be described. The TDC (top dead center) of each cylinder is detected by the reference signal REF. The first crank angle is obtained from the TDC using the angle signal POS and is set as the window start point Ws. The second crank angle is obtained from the window start point Ws using the same angle signal POS, and the window width W is defined from the first crank angle to the second crank angle.

  Now, let the window passage time of the cylinder in the ignition cycle be Tw (i), and determine the combustion state parameter D1A1 from the following <Equation 1>.

<Formula 1>
D1A1 = {Tw (i) −Tw (i−1)} / Tw3 (i) × k
However,
Tw (i): Window passage time of the cylinder currently in the ignition cycle Tw (i-1): Window passage time of the cylinder in the previous ignition cycle k: Calculation coefficient D1A1: Combustion state parameter

  FIG. 4 shows the behavior of the window passing time Tw (i) and the combustion state parameter D1A1 obtained by the equation (1) when the first cylinder # 1 misfires. In this case, the window width is 90 ° (CA) and the engine speed is 4000 rpm.

  When the combustion state is normal, the window passage times of the cylinders are substantially equal, so the combustion state parameter D1A1 is substantially 0. However, when misfire occurs, the misfire cylinder does not generate torque and the rotational speed decreases, so FIG. As shown in A), the value of the window passing time Tw (i) becomes large. At this time, the combustion state parameter D1A1 shows a certain positive value as shown in FIG. Therefore, the presence or absence of a misfired cylinder can be determined by comparing the combustion state parameter D1A1 with a preset value (determination value).

  Specifically, as shown in FIG. 5, the combustion state parameter D1A1 is compared with a preset determination value D1ATH, and when D1A1 ≧ D1ATH, it is determined that misfire has occurred, and the misfire counter CMTLB is counted up, and D1A1 When <D1ATH, the misfire count is not increased as a normal combustion state. When the count number of the misfire counter CMTLB exceeds a preset value (lighting threshold value MIL), a warning lamp on the meter panel is lit to warn the driver.

  FIG. 6 shows an example of misfire misjudgment that occurs during acceleration / deceleration. The figure shows the behavior of the combustion state parameter D1A1 in the throttle tip-in (accelerator pedal) mode that repeatedly accelerates and decelerates. The vehicle reverberation (disturbance such as vehicle longitudinal vibration) is triggered by torque fluctuation during acceleration / deceleration. As a result, the combustion state parameter D1A1 greatly fluctuates despite the normal combustion state, and as a result, the combustion state determination value D1ATH is exceeded, leading to misfire misjudgment.

  By repeating such an operation mode several times, the misfire counter CMTLB reaches the lighting threshold value MIL, leading to erroneous lighting.

  One way to solve the above problem is to strengthen the misfire count condition. That is, the combustion state parameter D1A1 increases at the time of “vehicle reverberation” at the time of acceleration / deceleration in addition to the occurrence of “misfire” and exceeds the combustion state determination value D1ATH, resulting in a misfire misjudgment. If a condition capable of determining the presence or absence of reverberation of the vehicle is added to the condition, the misjudgment of the misfire can be countered.

  For that purpose, it is necessary to reliably discriminate between “misfire” and “vehicle reverberation”, and the method will be described next.

  FIG. 7 shows the frequency analysis results of the throttle tip-in mode in which misfire misjudgment occurs and the window passage time Tw (i) when misfire occurs.

  From this result, the strength of the 0.1th order to 0.4th order component is larger at the time of throttle tip-in than at the time of misfire, and at the time of misfire, the 0.5th order which is the second rotation component of the crankshaft relative to the time of throttle tip-in There is a feature that the strength of the component is increased.

  Therefore, focusing on the 0.5th order component that is a characteristic at the time of misfire, the misfire and vehicle reverberation are discriminated from the level of the 0.5th order component.

  FIG. 8 shows a filter that extracts a 0.5th-order component, which is a feature at the time of misfire. Filter A in the figure is a filter that extracts the 0.5th-order, and the gain is maximum at the 0.5th-order. However, since the gain at the 0.4th order is large, there is a demerit that is easily affected by the reverberation of the vehicle.

  In addition, the filter B is a filter that is not easily affected by vehicle reverberation, and the gain of the 0.1th to 0.4th order is low, but the gain of the 0.7th order is the maximum, so other than the 0.5th order of the misfire band There is a demerit that also extracts the ingredients. By extracting the 0.5th order component by combining these two filters, the disadvantages of each filter can be offset, and the 0.5th order component can be reliably extracted.

  That is, the point is that both filters are designed so that the gains of the 0.5th order are the same. The parameter A (first combustion state reverberation parameter) created by these two filters, and the parameter When there is no difference in the value of B (second combustion state reverberation parameter), it can be determined as a 0.5th order component, so-called misfire. Conversely, if there is a difference between the values of the two parameters, it can be determined that there is a vehicle reverberation (combustion state reverberation) other than misfire.

  FIG. 9 is a diagram specifically showing a method of discriminating between misfire and vehicle reverberation. The first combustion state reverberation parameter D1AR05A is obtained by the filter A by the following <Equation 2>, and the filter B Then, the second combustion state reverberation parameter D1AR05B is obtained by the following <Expression 3>.

<Formula 2>
D05A1 = Tw (i-3)
D05A2 = D05A1 (i) -D05A1 (i-2)
D05A3 = D05A2 (i) -D05A2 (i-1)
D05A4 = D05A3 (i-1) -D05A3 (i)
D1AR05A = max (D05A4or0)
However,
(I): current calculated value,
(I-1): Previous calculation value

<Formula 3>
D05B1 = 1/2 × Tw (i-2)
D05B2 = D05B1 (i) -D05B1 (i-2)
D05B3 = D05B2 (i) -D05B2 (i-2)
D05B4 = D05B3 (i-2) -D05B3 (i)
D1AR05B = max (D05B4or0)
However,
(I): Current calculated value (i-1): Previous calculated value

  When the ratio or difference between the parameters D1AR05A and D1AR05B created in the above <Expression 2> and <Expression 3> is not less than the first determination value (MFECHO) and not more than the second determination value (MFECHO2) The 0.5th order component, so-called misfire, is determined, and the misfire counter is allowed to count. Conversely, when the value is less than the first determination value and exceeds the second determination value, it is determined that the vehicle is reverberant (that is, reverberation of the combustion state), and the misfire counter is prohibited from counting. To do.

A summary of the above misfire count conditions is shown below.
(A)... When the following conditions (i) and (ii) are satisfied, it is determined that there is no vehicle reverberation, and misfire counting is permitted.
(B)... When any of the following conditions (i) and (ii) is not established, the vehicle has reverberation and the misfire count is prohibited.
(I) D1AR05A ≧ MFECHO × D1AR05B
(Ii) D1AR05A <MFECHO2 × D1AR05B
Here, the first and second determination values MFECHO and MFECHO2 are obtained by the following <Expression 4> and <Expression 5>, respectively.

  Here, as shown in FIG. 10, the first determination value MFECHO and the second determination value MFECHO2 are switched in the search table depending on the operation state of the idle switch, that is, the idle state and the off-idle state. The point is.

<Formula 4>
・ In the case of off-idle state (when the idle switch is off) MFECHO = TMFECHO × TMFECHTW
・ In the idle state (when the idle switch is on) MFECHO = TMFECHO3 × TMFECHTW

<Formula 5>
・ In the case of off-idle state (when idle SW is off) MFECHO2 = TMFECHO2 × TMFECHTW
・ In the idle state (when idle SW is on) MFECHO2 = TMFECHO4 × TMFECHTW
However, TMFECHO, TMFECHO2, TMFECHO3, and TMFECHO4 are functions of the engine load because the required values vary depending on the engine load as shown in FIG. TMFECHTW is a correction coefficient at the engine water temperature, as shown in FIG.

  FIGS. 13, 14, and 15 are flowcharts showing an example of the combustion state diagnosis routine as described above, which is executed by the control unit 100. FIG.

  A series of processes shown in the flowchart of the drawing is repeatedly executed for each ignition. First, in step 801, a window passing time (a time required for rotating a predetermined crank angle) Tw (i) is measured. In step 802, the combustion state parameter D1A1 is calculated according to <Expression 1> described above. In Step 803, the first combustion state reverberation parameter D1AR05A is calculated according to <Expression 2> described above. The second combustion state reverberation parameter D1AR05B is calculated from Equation 3>.

  In the next step 805, it is checked whether or not the diagnosis condition is satisfied. When the diagnosis condition is not satisfied, this routine is ended as shown in FIG. When the diagnosis condition is satisfied, the routine proceeds to step 806, where the combustion state parameter D1A1 is compared with the combustion state determination value D1ATH.

  Here, if combustion state parameter D1A1 ≧ combustion state determination value D1ATH, it is determined that abnormal combustion (misfire) has occurred, and the routine proceeds to step 807 in FIG. 14, and when not established, as shown in FIG. This routine is finished.

  In step 807 of FIG. 14, it is determined whether or not the rotational speed condition of the first vehicle reverberation determination area is satisfied (NDATA ≦ KMFECON1). This is a condition for limiting the determination area because vehicle reverberation occurs at a specific rotation speed or less, and if established, the process proceeds to step 808. If not established, the condition is outside the vehicle reverberation determination area, that is, vehicle reverberation occurs. It is determined that misfire has occurred because the area is not, and the process proceeds to step 812 in FIG. 15 to increment the misfire counter by one and end this routine.

  In step 808 of FIG. 14, it is confirmed whether or not it is the second vehicle reverberation determination region (NDATA ≧ KMFECON2, VSP ≧ KMFECOV). Here, since the reverberation of the vehicle does not occur at a specific vehicle speed and a specific rotation speed or less, such as when the vehicle is stopped, it is a condition for further limiting the determination region. When the condition is satisfied, the process proceeds to step 809, and when the condition is not satisfied, the vehicle reverberation is performed. Since it is outside the determination area, that is, an area in which vehicle reverberation does not occur, it is determined that a misfire has occurred. In step 812 of FIG. 15, the misfire counter is incremented by 1, and this routine is terminated.

  In step 809, it is determined whether or not the idle switch is OFF, that is, in the off-idle state. If it is determined that the idle switch is in the off-idle state, the process proceeds to step 810 in FIG. Proceed to step 811.

  Steps 810 and 811 in FIG. 15 are used to determine misfire and vehicle reverberation based on the ratio or difference between D1A05A and D1AR05B calculated in steps 803 and 804. In the case of an off-idle state, step 810 is performed. Is determined in step 811. If the ratio or difference is equal to or greater than TMFECO or TMFECO3, which is the first determination value obtained in the above-described <Expression 4> and <Expression 5>, and is equal to or less than TMFECHO2 or YMFECO4, which is the second determination value, it is determined as misfire. In step 812, the misfire counter is incremented by 1, and this routine is terminated.

  In cases other than the above, it is determined that the vehicle is in reverberation, and this routine is terminated without passing through step 812 (without increasing the misfire count).

  FIG. 16 is a diagram showing changes in parameters and the like when the throttle tip-in mode is performed at an engine speed of 2000 rpm. Conventionally, in this mode, the combustion state parameter D1A1 has been set under the influence of vehicle reverberation. In this embodiment, the combustion state parameter D1A1 increases due to the effect of vehicle reverberation that occurs at the time of throttle tip-in, and exceeds the combustion state determination value D1ATH. Therefore, the condition of the step 806 is satisfied, but the comparison result condition of the first combustion state reverberation parameter D1AR05A and the second combustion state reverberation parameter D1AR05B of the step 811 is not satisfied, so that there is vehicle reverberation. It is judged, misfire counter CMFTLB is not counted up, misfire That there is no count of occurrence it will be appreciated.

  As a result, the combustion state diagnosis apparatus of the present embodiment can accurately determine the presence or absence of abnormal combustion (misfire) without being affected by disturbances or the like even during acceleration / deceleration.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram which shows one Embodiment of the combustion condition diagnostic apparatus which concerns on this invention with the vehicle-mounted engine to which it is applied. The functional block diagram which shows the combustion condition diagnostic content which the control unit shown by FIG. 1 performs. The figure which showed the change with respect to the crank angle of the engine speed at the time of misfire. The figure which shows the change of the window passage time (A) at the time of cylinder # 1 misfire, and the combustion state parameter (B). The figure used for description of the structure of misfire determination and misfire count. The figure used for description of the cause etc. which misfire misjudgment produces at the time of acceleration / deceleration. The figure which shows the frequency analysis result of the window passage time at the time of throttle tip-in. The figure used for description of the filter which extracts a 0.5th-order component. The figure used for description of a combustion state reverberation determination means. (A) shows an example of the first determination value and the second determination value in the off-idle state, and (B) shows an example of the first determination value and the second determination value in the idle state. The figure which shows an example of the combustion reverberation judgment value with respect to an engine load. The figure which shows an example of the combustion reverberation judgment value with respect to engine water temperature. The flowchart which shows the front | former stage part of an example of the combustion state diagnostic routine which a control unit performs. The flowchart which shows the intermediate part of an example of the combustion state diagnostic routine which a control unit performs. The flowchart which shows the back | latter stage part of an example of the combustion state diagnostic routine which a control unit performs. The figure used for description of the effect of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Engine 100: Control unit 101: Required time measurement means 102: Combustion state parameter calculation means 103: 1st combustion state reverberation parameter calculation means 104: 2nd combustion state reverberation parameter calculation means 105: Combustion state reverberation determination means 106 : Combustion state determination means 200: Air cleaner 201: Ignition device 202: Fuel injection valve 203: Rotational speed sensor 204: Air flow sensor 205: Air-fuel ratio sensor 213: Throttle valve 214: Combustion chamber
# 1, # 2, # 3, # 4: Cylinder

Claims (11)

A required time measuring means crankshaft measures the time required to rotate the predetermined angle, the first parameter calculation means for calculating a first combustion state reverberation parameters from the required time, the second from the required time Reverberation for determining whether or not a combustion state reverberation state is obtained based on the first combustion state reverberation parameter and the second combustion state reverberation parameter. A combustion state diagnosis device for an engine, comprising: a determination unit; and a combustion state determination unit that determines presence or absence of abnormal combustion such as misfire based on a determination result of the reverberation determination unit ,
The first and second parameter calculation means extract a crankshaft two rotation period signal,
The first combustion state reverberation parameter calculated by the first parameter calculation unit is other than the crankshaft two-rotation component with respect to the second combustion state reverberation parameter calculated by the second parameter calculation unit. An engine combustion state diagnosing device characterized in that components have different intensities .   The reverberation determination unit is configured to detect a combustion state reverberation state when a ratio or difference between the first combustion state reverberation parameter and the second combustion state reverberation parameter is equal to or smaller than a first determination value or equal to or greater than a second determination value. The engine combustion state diagnosis apparatus according to claim 1, wherein   The engine combustion state diagnosis apparatus according to claim 2, wherein the first determination value and the second determination value are switched according to an operating state of an idle switch or a throttle opening.   The engine combustion state diagnosis apparatus according to claim 2, wherein the first determination value and the second determination value are functions of an engine load.   The engine combustion state diagnosis apparatus according to claim 2, wherein the first determination value and the second determination value are functions of engine water temperature.   6. The engine combustion state diagnosis apparatus according to claim 1, wherein the reverberation determination unit performs the determination when the engine speed is a predetermined value or less.   6. The engine combustion state diagnosis apparatus according to claim 1, wherein the reverberation determination unit performs the determination when the engine speed is equal to or higher than a predetermined value and the vehicle speed is equal to or higher than a predetermined value.   Combustion state parameter calculating means for calculating a combustion state parameter, wherein the combustion state determining means determines the presence or absence of abnormal combustion based on the combustion state parameter and the determination result of the reverberation determining means. Item 8. The engine combustion state diagnostic device according to any one of Items 1 to 7.   The engine combustion state diagnosis apparatus according to claim 8, wherein the combustion state parameter is a difference between the required times at the time of current ignition and at the time of previous ignition.   The combustion state determination means determines that abnormal combustion has occurred when the combustion state parameter is not less than a predetermined determination value and the reverberation determination means determines that the combustion state reverberation state is not present. The engine combustion state diagnosis apparatus according to claim 8 or 9.   The engine according to any one of claims 8 to 10, wherein the predetermined determination value compared with the combustion state parameter in the combustion state determination means is a function of an engine speed and / or an engine load. Combustion state diagnostic device.

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