JPH06129299A - Misfire judgement device of internal combustion engine - Google Patents

Abstract

PURPOSE:To make a proper judgement on an abnormal combustion state, whether a sensor detecting an engine driving state and others is at the normal time or at the time of abnormality detection. CONSTITUTION:The number of misfire generation for each 200 rotations of a crankshaft is measured by a counter A, the number of flame-out generation for each 1000 rotations of the crankshaft is measured by a counter B, and when respective count value is higher than specified threshold value MMTDCCAT, MFTDCEMSTD, it is judges as abnormal (S49-S51). At the time when sensors to judge whether a misfire judgement (monitor) execution condition is established or not and others are normal (answer to S47 is NO), abnormality judgement in accordance with measured value of the counters A and B, while at the time when the sensors and others detect failure (answer to A47 is YES), only judgement in accordance with the measured value of the counter A is carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the combustion state (misfire state) of an engine based on the variation of the crankshaft rotational angular velocity of the internal combustion engine in each combustion cycle.

[0002]

2. Description of the Related Art As a method for detecting a cylinder in which normal combustion is not performed due to a failure of an engine ignition system, a fuel supply system, or the like, the magnitude of variation in the crankshaft angular velocity for each combustion cycle is detected. However, an abnormality detection device (for example, Japanese Patent Laid-Open No. 3-286166) that determines the presence / absence of a cylinder abnormality based on the magnitude of the fluctuation amount is conventionally known.

[0003]

However, in the above-mentioned conventional apparatus, it is determined whether the sensor for detecting the crankshaft angular velocity, which is directly involved in the determination of the combustion state, or the engine operating state in which the determination of the combustion state should be performed. There has been no consideration of a sensor (for example, an engine cooling water temperature sensor, an intake air temperature sensor, an intake pipe absolute pressure sensor) for making a determination, or a coping method when an abnormality occurs in a component involved in fuel supply control. Therefore, there is a tendency that the combustion state is often determined to be abnormal when a sensor or the like for detecting whether or not the operation state is to be particularly determined is abnormal, and there is room for improvement.

The present invention has been made in view of the above-mentioned points, and it is possible to appropriately determine the abnormality of the combustion state in both the normal state and the abnormal state of the sensor for detecting the engine operating state or its peripheral parts. It is an object of the present invention to provide a misfire determination device capable of performing the above.

[0005]

To achieve the above object, the present invention provides a first sensor for determining a predetermined operating state of an internal combustion engine, and a second sensor for detecting a predetermined operating parameter of the engine. And, when the operating state of the engine is the predetermined operating state, the engine misfire is determined by comparing a misfire determination parameter calculated based on a predetermined operating parameter of the engine and a predetermined determination value. In the misfire determination device for an internal combustion engine, the determination value changing means for changing the predetermined determination value according to whether or not the first sensor is out of order is provided.

[0006]

A first sensor for judging a misfire by comparing a predetermined judgment value with a misfire judgment parameter calculated based on a predetermined operation parameter of the engine in a predetermined operation state of the engine, and a first sensor for judging the predetermined operation state. The predetermined determination value is changed depending on whether or not the failure occurs.

[0007]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of an internal combustion engine and a combustion state detecting apparatus therefor according to one embodiment of the present invention. A throttle valve 3 is arranged in the intake pipe 2 of the engine 1. The throttle valve 3 has a throttle valve opening (θTH)
The sensor 4 is connected, and outputs an electric signal according to the opening degree of the throttle valve 3 and supplies it to an electronic control unit (hereinafter referred to as “ECU”) 5.

The fuel injection valve 6 is provided for each cylinder between the engine 1 and the throttle valve 3 and slightly upstream of the intake valve (not shown) of the intake pipe 2, and each injection valve is connected to a fuel pump (not shown). The valve opening time of fuel injection is controlled by a signal from the ECU 5 that is electrically connected to the ECU 5.

On the other hand, a pipe 7 is provided immediately downstream of the throttle valve 3.
The intake pipe absolute pressure (PBA) sensor 8 is provided via the, and the absolute pressure signal converted into an electric signal by the absolute pressure sensor 8 is supplied to the ECU 5. Further, an intake air temperature (TA) sensor 9 is attached downstream thereof,
EC is detected by detecting the intake air temperature TA and outputting the corresponding electric signal.
Supply to U5.

The engine water temperature (TW) sensor 10 mounted on the main body of the engine 1 is composed of a thermistor or the like, detects the engine water temperature (cooling water temperature) TW, outputs a corresponding temperature signal and supplies it to the ECU 5.

A signal pulse (hereinafter referred to as "CYL signal pulse") is generated around a cam shaft (not shown) or a crank shaft of the engine 1 at a predetermined crank angle position of a specific cylinder of the engine 1.
Cylinder discrimination sensor (hereinafter referred to as “CYL sensor”) 13 for outputting a crank angle position that is a predetermined crank angle before the top dead center (TDC) at the start of the intake stroke of each cylinder (a crank angle of 180 for a 4-cylinder engine). Every °) T
A TDC sensor 12 that generates a DC signal pulse, and one pulse (hereinafter “CRK signal pulse”) at a constant crank angle (for example, 30 °) cycle shorter than the cycle of the TDC signal pulse.
A crank angle sensor (hereinafter, referred to as “CRK sensor”) 11 for generating a CYL signal pulse, a TDC signal pulse, and a CRK signal (crank angle signal) pulse are supplied to the ECU 5.

A spark plug 14 is provided in each cylinder of the engine 1.
It is provided and connected to the ECU 5.

The three-way catalyst (catalyst converter) 16 is arranged in the exhaust pipe 15 of the engine 1 and contains H in the exhaust gas.
Purifies components such as C, CO, and NOx. An oxygen concentration sensor is mounted on the exhaust pipe 15 on the upstream side of the three-way catalyst 16. The O ₂ sensor 17 detects the oxygen concentration in the exhaust gas and sends an electric signal to the ECU 5 according to the detected value. Supply.

The ECU 5 is further connected to a vehicle speed sensor 18 for detecting the traveling speed of a vehicle equipped with the engine 1 and an atmospheric pressure sensor 19 for detecting atmospheric pressure. The signal is supplied to the ECU 5.

The ECU 5 shapes the input signal waveforms from various sensors, corrects the voltage level to a predetermined level, and converts the analog signal value into a digital signal value. "CPU") 5b, various calculation programs executed by the CPU 5b, storage means 5c for storing the calculation results, an output circuit 5d for supplying a drive signal to the fuel injection valve 6, and the like.

The CPU 5b discriminates various engine operating states based on the above-mentioned various engine parameter signals, and according to the engine operating state, the fuel injection time of the fuel injection valve 6 synchronized with the TDC signal pulse and the ignition plug 14 The ignition timing is calculated and a signal for driving the fuel injection 26 and the spark plug 14 is output via the output circuit 5d.

In this embodiment, the ECU 5 constitutes a judgment value changing means.

FIG. 2 is a diagram showing the overall configuration of a program (executed by the CPU 5b) for determining the combustion state of the engine 1.

FIG. 4A shows a CRK process which is executed in synchronization with each generation of the CRK signal pulse, and in this process, the CRK signal pulse generation time interval (proportional to the reciprocal of the engine speed). An average value (hereinafter referred to as "first average value") TAVE of the parameter is calculated (step S1).

FIG. 2B shows TDC and processing executed in synchronization with each generation of the TDC signal pulse,
In this process, the first average value TAV calculated in the CRK process
Whether or not a misfire has occurred in the engine 1 is determined based on the amount of change ΔM in the average value of E (hereinafter referred to as the “second average value”) M (step S3), and the number of times misfire is determined in step S3. Based on the abnormality determination (step S4).

FIG. 3 is a flow chart of a program for calculating the first average value TAVE.

In step S11, the CRK signal pulse generation time interval CRMe (n) is measured. Specifically, as shown in FIG. 4, C is sequentially output every 30 degrees of rotation of the crankshaft.
RMe (n), CRMe (n + 1), CRMe (N +
2) ... Is measured.

At step S12, 1 is obtained by the following equation (1).
The first average value TAVE (n) is calculated as the average value of 12 CRMe values from the previous measured value CRMe (n-11) to the latest measured value CRMe (n).

[0025]

[Equation 1] In this embodiment, the CRK signal pulse is generated each time the crankshaft rotates 30 degrees, so the first average value TAVE (n) is obtained.
Is an average value corresponding to one revolution of the crankshaft. By performing such an averaging process, one revolution of the crankshaft results in one
It is possible to remove the primary vibration component of the engine rotation in a cycle, that is, the noise component due to the mechanical error (manufacturing error, mounting error, etc.) of the pulsar or the pickup that constitutes the crank angle sensor 11.

The engine speed NE is calculated based on the TAVE (n) value.

FIG. 5 is a flowchart specifically showing the processing in step S2 of FIG. 2 (b).

In step S21, according to the following equation (2),
The calculated value TAVE (n- 5 times before the first average value TAVE
6 TAs from 5) to the latest calculated value TAVE (n)
The second average value M (n) is calculated as the average value of the VE values.

[0029]

[Equation 2] In the present embodiment, the engine 1 is a four-cylinder, four-cycle engine, and ignition is performed in any cylinder whenever the crankshaft rotates 180 degrees. Therefore, the second average value (n)
Is the average value of the first average value TAVE (n) for each ignition cycle. By performing such an averaging process, it is represented as a torque fluctuation amount of engine rotation due to combustion.
The secondary vibration component, that is, the vibration component of the crankshaft half rotation cycle can be removed.

In the following step S22, the high-pass filter processing of the second average value M (n) is performed by the following equation (3). The second average value after high-pass filtering is FM
(N).

FM (n) = b (1) × M (n) + b (2) × M
(N-1) + b (3) * M (n-2) -a (2) FM (n-1)
-A (3) FM (n-2) (3) Here, b (1) to b (3), a (2) and a (3) are filter transfer coefficients, for example, 0.2096, -0.4192,
It is set to 0.2096, 0.3557, and 0.1940. Further, both FM (0) and FM (1) have a value of 0, and equation (3) is applied to n having a value of 2 or more.

By this high-pass filter processing, M
(N) Low frequency components of about 10 Hz or less included in the value can be removed to remove the influence of vibration transmitted from the drive system to the engine (for example, vibration caused by twisting of the crankshaft, road surface vibration transmitted from tires, etc.). it can.

In a succeeding step S23, a change amount ΔM (n) of the second average value FM (n) subjected to the high pass filter processing.
Is calculated by the following equation (4).

ΔM (n) = FM (n) −FM (n−1) (4) The second average value FM after high-pass filtering
Since the polarity of (n) is reversed from that of the M (n) value, when a misfire occurs in the engine 1, the M (n) value increases, so the FM (n) value increases in the negative direction, and ΔM The (n) value also tends to increase in the negative direction.

FIG. 6 is a flow chart of a program for making a misfire determination and a misfiring cylinder determination based on the change amount .DELTA.M calculated as described above.

In step S31, it is determined whether or not the monitor execution condition, that is, the misfire determination can be executed. The monitoring execution condition is satisfied, for example, when the engine operating state is in a steady state and the engine water temperature TW, the intake air temperature TA, the engine rotation speed NE, etc. are within predetermined ranges.

When the monitor execution condition is not satisfied, this program is immediately terminated, and when the monitor execution condition is satisfied, whether or not the change amount ΔM is smaller than a negative predetermined value MSLMT (| ΔM | is | MSLMT). | Good or not). Here, a negative predetermined value MSLMT
Is read from a map set according to the engine speed NE and the engine load (intake pipe absolute pressure PBA) as shown in FIG. The absolute value of the MSLMT value is set to be smaller as the engine speed NE increases and set to be larger as the engine load increases.

When the answer in step S32 is negative (NO), that is, when ΔM ≧ MSLMT is satisfied, the program ends immediately. When the answer in step S32 is affirmative (YES), that is, ΔM <MSLMT is satisfied, the previous ignition is performed. It is determined that a misfire has occurred in the cylinder. This is because, as described above, the value of ΔM (n) increases in the negative direction when a misfire occurs.

The reason why it is determined that the misfire has occurred in the previously ignited cylinder is that a delay occurs due to the high-pass filter processing.

When the high-pass filter processing is not performed, the second average value M (n) is used as it is to calculate the change amount ΔM (n), so that polarity inversion does not occur. Therefore, the predetermined value MSLMT for misfire determination is a positive value,
It suffices to set the polarity of FIG. 7 to be reversed. MSLMT
The setting tendency in terms of absolute value is the same as that in FIG. In this case, step S33 determines that misfire has occurred in the ignition cylinder of this time. This is because there is no delay due to the high-pass filter processing.

As described above, according to this embodiment, the CR
A first average value TAVE is calculated by averaging the measured value CRMe of the K signal pulse generation time intervals in the cycle of one rotation of the crankshaft, and further the TAVE value is averaged in the cycle of half rotation of the crankshaft. Therefore, the second average value M
(N) is calculated, and the misfire determination is performed based on the change amount ΔM of the second average value M (n). Therefore, the influence of mechanical error components such as the crank angle sensor mounting error and the combustion fluctuation component is determined. It can be removed and a misfire determination can be made. As a result, stable misfire determination can be performed, and the accuracy of misfire detection can be improved.

FIG. 8 is a flowchart of the misfire rate verification process executed in step S4 of FIG. 2 (b).

In step S41, it is determined whether or not a component or sensor for misfire determination, specifically, the CRK sensor 11, TDC sensor 12, CYL sensor 13 and peripheral components thereof, is detected, and the failure is detected. When not detected, it is determined whether or not the crankshaft rotation fluctuation (ΔM) for 200 rotations has been continuously measured after the resetting of the counter A which is reset in step S53 described later (step S42). The counter A is a counter that counts the number of times misfire is determined while the crankshaft rotates 200 times.

At the time of failure detection of a sensor for misfire determination or 2
When the measurement for 00 rotations has not been completed, this processing is immediately terminated, while when the measurement for 200 rotations is performed, the crankshaft rotation fluctuation for 1000 rotations is continuously measured after the counter B is reset. It is determined whether or not (step S43). Counter B has 100 crankshafts
It is a counter that counts the number of times misfire is determined during 0 revolutions.

When the measurement for 1000 revolutions is not completed, the flag F200 indicating that the measurement for 200 revolutions is completed is set to the value 1 (step S4).
5) When completed, flag F100 indicating that
0 is set to the value 1 (step S46). In the following step S46, the number of misfire TDCs for NG determination MFTDCEMS
TD and MFTDCCAT are respectively MFTDCEMS
Search from the TD map and the MFTDCCAT map.
MFTDCEMSTD is a first threshold value (predetermined determination value) used for the determination in step S49 described later, and corresponds to the misfire rate (the number of misfire occurrences during 1000 revolutions) at which the unburned exhaust gas becomes equal to or higher than the allowable standard. Also MFTDCCAT
Is a second threshold value (predetermined determination value) used in the determination of step S50 described later, and corresponds to the misfire rate (the number of misfire occurrences during 200 revolutions) that may damage the three-way catalyst 16. To do. Here, the first and second thresholds are
MFTDCCAT / 200> MFTDCEMSTD / 1
There is a relationship of 000. In addition, MFTDCEMSTD
The map and the MFTDCCAT map are MFTD according to the engine speed NE and the intake pipe absolute pressure PBA, respectively.
It is a map in which the CEMSTD value and the MFTDCCAT value are set, and the set value is set to decrease as the NE value increases and the PBA value increases.

In the following step S47, a component or sensor for determining the monitor execution condition (see FIG. 6, step S31), specifically, the engine water temperature sensor 10, the intake temperature sensor 9, the intake pipe absolute pressure sensor 8, the throttle. It is determined whether or not a failure of the valve opening sensor 4, the vehicle speed sensor 18, the atmospheric pressure sensor 19 or the like or peripheral parts thereof is detected, and when a failure is detected, a misfire rate test based on the value of the counter A is performed. Only (steps S50 to S5
2). That is, the value of the counter A is the second threshold value MFTD.
It is determined whether or not CCAT or more (step S50), and A <
When MFTDCCAT is established, it is determined to be normal (step S52), and when A ≧ MFTDCCAT is established, it is determined to be abnormal (step S53).

If the answer to step S47 is negative (NO),
That is, when the failure of the sensor for monitoring execution condition determination or the like is not detected, it is determined whether or not the flag F200 is 1 (step S48), and when F200 = 1, 1 is set.
Since the measurement for 000 revolutions has not been completed, the process proceeds to step S50, and only the misfire rate test based on the value of the counter A is performed. On the other hand, when F200 = 0, the measurement for 1000 revolutions has been completed, so the misfire rate test based on the value of the counter B is first performed (step S49). That is, it is determined whether or not the value of the counter B is equal to or larger than the first threshold value MFTDCEMSTD, and when B ≧ MFTDCEMSTD is satisfied, it is determined to be abnormal (step S51), and B <MF.
When TDCEMSTD is established, the above step S5 is executed.
Go to 0.

In the following step S53, the counter A and the flag F200 are reset, and then F1000 =
When it is 1, the counter B and the flag F1000 are reset (step S55), and this processing ends.

According to steps S47 to S52 of FIG.
When the failure of the sensor for monitoring execution condition determination is not detected, both the determination based on the value of the counter A and the determination based on the value of the counter B are executed, and the value of the counter A is detected when the failure is detected. Only the judgment based on is executed.
This is because the accuracy of the misfire determination may not be sufficiently secured when the monitor execution condition determination sensor or the like fails, or the air-fuel ratio of the air-fuel mixture supplied to the engine may deviate from the desired value and the unburned exhaust gas component may increase. This is because there is a possibility that the normal combustion state may be determined to be misfire if the detection accuracy decreases and as a result the determination based on the value of the counter B is executed.

Further, when the monitor execution condition determination sensor or the like is normal, the determination based on the value of the counter A is performed every 200 rotations, and the determination based on the value of the counter B is performed every 1000 rotations. It is possible to reliably detect a relatively slight abnormality.

As described above, according to the present embodiment, it is possible to appropriately determine the abnormality of the combustion state of the engine when the monitor execution condition determination sensor or the like is normal and when the abnormality is detected.

In this embodiment, step S4 in FIG.
In 7, but so as to determine whether or not to detect the abnormality of the sensor and peripheral parts thereof for determining monitoring conditions, not limited thereto, for example, O ₂ sensor 1
7. A sensor that may affect the air-fuel ratio of the air-fuel mixture, such as an abnormality in an exhaust gas recirculation amount control valve in an engine equipped with an exhaust gas recirculation mechanism or an evaporated fuel purge amount control valve in an engine equipped with an evaporated fuel processing device, It may be determined whether or not an abnormality of a component or the like is detected, and only the determination based on the value of the counter A may be performed when the abnormality is detected.

[0053]

As described in detail above, according to the present invention, a misfire is determined by comparing a predetermined determination value with a misfire determination parameter calculated based on a predetermined operating parameter of the engine in a predetermined operating state of the engine. Since the predetermined determination value is changed depending on whether the first sensor for determining the predetermined operation state has failed,
It is possible to appropriately determine whether the combustion state of the sensor is abnormal or not, whether the sensor is normal or abnormal.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of an internal combustion engine and a control system therefor according to an embodiment of the present invention.

FIG. 2 is a diagram showing an overall configuration of a program for determining a combustion state.

FIG. 3 is a flowchart showing a part of the processing contents of FIG. 2 in detail.

FIG. 4 is a diagram for explaining a relationship between measurement of a parameter indicating an engine rotation speed and a rotation angle of a crankshaft.

5 is a flowchart showing a part of the processing contents of FIG. 2 in detail.

FIG. 6 is a flowchart showing a part of the processing contents of FIG. 2 in detail.

FIG. 7 is a diagram for explaining a method of setting a misfire determination threshold value (MSLMT).

FIG. 8 is a flowchart showing a part of the processing contents of FIG. 2 in detail.

[Explanation of reference numerals] 1 internal combustion engine 4 throttle valve opening sensor 5 electronic control unit (ECU) 8 intake pipe absolute pressure sensor 9 intake air temperature sensor 11 crank angle sensor 12 TDC sensor 17 O ₂ sensor 18 vehicle speed sensor 19 atmospheric pressure sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuichi Shimazaki 1-4-1 Chuo, Wako City, Saitama Prefecture Honda R & D Co., Ltd.

Claims (2)

[Claims] 1. A first sensor for determining a predetermined operating state of an internal combustion engine, and a second sensor for detecting a predetermined operating parameter of the engine, wherein the operating state of the engine is the predetermined operating state. In the state, the internal combustion engine misfire determination device for determining misfire of the engine by comparing a misfire determination parameter calculated based on a predetermined operating parameter of the engine with a predetermined determination value, wherein the first sensor is used. A misfire determination device for an internal combustion engine, comprising: determination value changing means for changing the predetermined determination value according to whether or not the engine is out of order. 2. The misfire determination device for an internal combustion engine according to claim 1, wherein the predetermined determination value is a misfire rate.