JP2000240500A - Method and device for detecting misfire of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high reliability misfire discrimination reference. SOLUTION: The rotation angular velocity of an output shaft is measured corresponding to a rotation angle at each measuring point of time and a difference between the rotation angular velocity and an average rotation angular velocity is determined as an angular velocity fluctuation amount Fn. Further, based on a predetermined angular velocity fluctuation reference Fs and the angular velocity fluctuation amount Fn, an angular velocity fluctuation difference G is led out and based on the led-out angular velocity fluctuation difference G, an angular velocity fluctuation difference amount Da in a given stroke is led out. In discrimination of the misfire state of an internal combustion engine based on the angular velocity fluctuation difference amount Da, in a first operation state considered as a normal operation state, the angular velocity fluctuation difference amount Da is detected a plurality of times. Probability distribution of the angular velocity fluctuation difference amount Da where the angular velocity fluctuation difference amount Da forms a probability function is determined. Based on the determined probability distribution, an angular velocity fluctuation difference reference value Dt to discriminate an abnormality combustion region is set and the misfire of an internal combustion engine is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to detecting a combustion failure and misfire of a multi-cylinder internal combustion engine for power generation.

[0002]

2. Description of the Related Art As a conventional device for detecting misfire of an internal combustion engine, a special sensor is attached to detect a combustion state,
There is a type in which a temperature sensor is attached near the exhaust port to determine a decrease in exhaust temperature at the time of misfire, or a type in which misfire is detected by detecting rotation fluctuation and detecting a decrease in rotation speed.

[0003]

According to the above-mentioned prior art, In the rotation fluctuation detection type misfire detection device, when the rotation angular velocity changes due to factors such as load fluctuation other than misfire,
This may be erroneously detected. 2. When a certain degree of operation is possible even when a misfire has occurred, as in the case of a generator engine, urgently stopping the engine and recovering from the failure lacks stability of power supply. In other words, it is necessary to rationally set the criteria. However, in a state where an engine failure or an accident occurs, the engine must be stopped even if the power supply is stopped. For this reason, an amount indicating the degree of misfire such as misfire or poor combustion (referred to as misfire amount in the present application)
It is necessary to use a value that depends on the explosive power of each cylinder as much as possible. If the absolute value of the rotation fluctuation is simply used, the explosive power normally generated for each load differs, so that the misfire amount cannot be directly estimated from the fluctuation amount. 3. In the rotation fluctuation detection, the tendency of the rotation fluctuation of the engine differs depending on the state of the load. Therefore, when the rotation fluctuation is detected by one method, the accuracy is good for one load, but may be poor for another load. This is because the rotational characteristics of the engine change depending on the load of the engine.
Also, a change in the engine speed affects the load side and further changes the load. For this reason, there is a drawback that the parameters required by the fixed analysis method alone become too large and it is difficult to cope with them.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a low-cost and accurate engine abnormal combustion and misfire by utilizing a rotational speed detection sensor and the like and a generated power signal used in an electronically controlled engine. It is an object of the present invention to provide a misfire detection device capable of measuring and determining the misfire.

[0005]

In order to achieve this object, the characteristic structure of the method for detecting misfire of an internal combustion engine according to the present invention is as follows.
As described in claim 1, the rotational angular velocity of the output shaft of the internal combustion engine is measured corresponding to the rotational angle at each measurement time, and the measured rotational angular velocity and the rotational angular velocity are measured. The difference from the average rotation angular velocity for a certain period before the measurement time point is defined as the angular velocity fluctuation amount Fn, and the angular velocity fluctuation amount reference Fs obtained in advance corresponding to the rotation angle of the output shaft at each measurement time point, and the measurement each time point The angular velocity fluctuation difference G is derived based on the angular velocity fluctuation amount Fn derived by the following equation, and based on the derived angular velocity fluctuation difference G,
A misfire detection method for an internal combustion engine that derives an angular velocity variation difference Da within a predetermined stroke and determines a misfire state of the internal combustion engine based on the angular velocity variation difference Da. In an operation state, the angular velocity variation difference Da is detected a plurality of times, and the angular velocity variation difference D is detected.
a probability distribution of the angular velocity variation difference Da having a as a probability function is determined as a first probability distribution, and angular velocity variation for determining an abnormal combustion region is determined based on the determined first probability distribution of the angular velocity variation difference Da. A difference reference value Dt is set, and misfire of the internal combustion engine is detected based on the angular speed variation difference reference value Dt. When this method is employed, the angular velocity variation difference is adopted as a misfire discrimination index, the internal combustion engine in a normal operating state is operated in advance, and the angular velocity variation difference Da obtained in this operating state is statistically calculated. The data is regarded as a random variable, and if its occurrence probability is very low, it is considered that an abnormality has occurred. By doing so, misfire detection that matches the actual situation of the internal combustion engine to be detected can be performed. In this case, the angular velocity variation difference Da
In deriving, as shown in an embodiment described later,
If the determination is made by detecting an abnormal change except the angular velocity change due to the load change applied to the internal combustion engine, the reliability of the determination can be improved.

As a device for determining misfire of an internal combustion engine by such a method, the rotation angular velocity of the output shaft of the internal combustion engine corresponds to the rotation angle at each measurement time. And the difference between the measured rotational angular velocity and the average rotational angular velocity for a certain period before the measurement time point at which the rotational angular velocity is measured.
The angular velocity variation deriving means derived as n, and the angular velocity variation reference Fs determined in advance by the angular velocity variation deriving means in correspondence with the rotation angle of the output shaft at each measurement point in time.
And the angular velocity variation Fn derived at each time point of the measurement.
And an angular velocity difference deriving means for deriving an angular velocity variation difference G, and an angular velocity variation difference Da within a predetermined stroke is derived based on the angular velocity variation difference G derived by the angular velocity difference deriving means. , The angular velocity variation difference Da
A misfire detection device for an internal combustion engine, which comprises a misfire determining means for determining a misfire state of the internal combustion engine based on the following formula. In the first operation state that can be regarded as a normal operation state, the angular velocity fluctuation difference Da is a probability function. A probability distribution of the angular velocity variation difference Da is determined, and based on the determined probability distribution of the angular velocity variation difference Da, an angular velocity variation difference reference value Dt for determining an abnormal combustion region is set, and misfire determination means is provided. Can be achieved by detecting the misfire of the internal combustion engine based on the angular velocity variation difference reference value Dt.

In order to achieve the above object, a method for detecting a misfire of an internal combustion engine according to the present invention is characterized in that the rotational angular velocity of the output shaft of the internal combustion engine is determined by the following method.
While measuring according to the rotation angle at each point in time,
The difference between the measured rotational angular velocity and the average rotational angular velocity for a certain period before the measurement time point at which the rotational angular velocity is measured is defined as an angular velocity fluctuation amount Fn, which is obtained in advance in correspondence with the rotational angle of the output shaft at each measurement time point. Angular velocity fluctuation reference Fs
And the angular velocity variation Fn derived at each time point of the measurement.
, An angular velocity variation difference G is derived, and based on the derived angular velocity variation difference G, an angular velocity variation difference Da within a predetermined stroke is derived, and based on the angular velocity variation difference Da. A misfire detection method for an internal combustion engine that determines a misfire state of the internal combustion engine, wherein the angular velocity variation difference D is set in a first operation state that can be regarded as a normal operation state.
a is detected a plurality of times, and a first representative value which is a representative value (for example, an average value) of the angular velocity variation difference Da is obtained.
In a second operating state that can be regarded as a forced misfire operation state, the angular velocity variation difference Da is detected a plurality of times, and a second representative value that is a representative value (for example, an average value) of the angular velocity variation difference Da is obtained. It is to obtain a misfire amount from a relationship between a unit misfire average angular velocity change amount Dm, which is a difference between the representative value and the second representative value, and an angular speed change amount Da measured in an internal combustion engine in an operating state. . In this method, the amount defined as the misfire amount can be called a misfire frequency, and such a misfire amount is not conventionally known. In this method, the angular velocity variation difference D in the first operating state
In addition to obtaining the statistical distribution of a, for example, the average value is obtained as a first representative value. The first representative value is an angular velocity fluctuation difference obtained from rotation fluctuation that occurs when the engine is in a normal operation state. On the other hand, a statistical distribution of the angular velocity variation difference Da in the second operating state is obtained, and, for example, an average value thereof is obtained as a second representative value. This second
The representative value is an angular velocity fluctuation difference obtained from rotation fluctuation generated when the engine generates a unit misfire. For example, in a multi-cylinder internal combustion engine, this data is obtained by forcibly misfiring a single cylinder, collecting data in that state, and calculating the average value of the angular velocity variation difference. Can be. Since the difference between the first representative value and the second representative value can be regarded as the unit misfire average angular velocity variation difference Dm, the difference between the unit misfire average angular velocity variation difference Dm and the internal combustion engine operating state is measured. Angular velocity variation difference Da
(For example, the ratio thereof), this value becomes a value representing the misfire frequency. By knowing the amount of misfire in this way, it is possible to evaluate the misfire state of the engine,
Misfire determination can be performed.

According to a fifth aspect of the present invention, there is provided a misfire determination device for determining the amount of misfire, which measures a rotational angular velocity of an output shaft of an internal combustion engine in accordance with a rotational angle at each measurement time. An angular velocity fluctuation deriving means for deriving, as an angular velocity fluctuation Fn, a difference between the measured rotational angular velocity and an average rotational angular velocity for a predetermined period before the measurement of the rotational angular velocity, and deriving the angular velocity fluctuation Means for calculating an angular velocity variation difference based on the angular velocity variation reference Fs previously determined corresponding to the rotation angle of the output shaft at each measurement time and the angular velocity variation Fn derived at each measurement time. An angular velocity difference deriving unit that derives G, and based on the angular velocity variation difference G derived by the angular velocity difference deriving unit, derive an angular velocity variation difference Da within a predetermined stroke, A misfire detection device for an internal combustion engine, comprising: a misfire determination unit configured to determine a misfire state of the internal combustion engine based on the angular speed variation difference Da. A representative value of the first representative value and a representative value of the angular velocity variation difference Da in a second operating state that can be regarded as a forced misfire operating state are defined as a second representative value. A misfire amount discriminating means for obtaining a misfire amount from the relationship between the unit misfire average angular velocity fluctuation difference Dm, which is the difference, and the angular velocity fluctuation difference Da measured in the internal combustion engine in the operating state can be provided.

In the case where the misfire amount is obtained as described above, as set forth in claim 3, the angular velocity variation difference amount reference value Dtf with respect to the reference misfire amount is calculated by calculating the unit misfire average angular velocity. It is preferable that misfire information is generated when the angular velocity variation difference Da measured in advance from the variation difference Dm exceeds the angular velocity variation difference determination reference value Dtf. By doing so, the misfire determination can be performed with a relatively simple configuration on a reasonable basis. According to an apparatus configuration corresponding to this configuration, an angular velocity variation difference determination reference value Dtf with respect to a determination reference misfire amount is obtained from the unit misfire average angular velocity variation difference amount Dm and measured. Angular velocity fluctuation difference Da
However, when misfire exceeds the angular velocity variation difference determination reference value Dtf, misfire information is generated, so that a misfire detection device for an internal combustion engine having a desired configuration in the present application can be obtained.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a misfire detection device 10 according to the present invention.
0 is a functional block diagram. As shown in FIG. 1, the misfire detection device 100 includes an angular velocity measuring unit 101 that measures a rotational angular velocity of an output shaft of an internal combustion engine in accordance with a rotational angle at each measurement time point, and a measurement that measures the rotational angular velocity. Mean rotational angular velocity for a certain period before the time and the angular velocity measuring means 1
The angular velocity fluctuation deriving means 102 derives the difference from the rotational angular velocity measured by the above-mentioned method as the angular velocity fluctuation Fn at each measurement time, and measures the output of the internal combustion engine at each measurement time from the generated power. Load condition measuring means 10
3 is provided as a main measurement system. The apparatus further includes a reference angular velocity fluctuation amount generating means 104 for generating an angular velocity fluctuation amount reference Fs which is obtained in advance corresponding to the rotation angle of the output shaft at each time of the measurement. The angular velocity variation deriving means 1 at each time point
A plurality of angular velocity difference deriving means 105 for obtaining an angular velocity variation difference G based on the angular velocity variation Fn derived by the step S04. The angular velocity difference deriving means 105 includes a plurality of such means, and the angular velocity fluctuation amount Fn measured in a preset rotation range.
In order to derive the angular velocity fluctuation difference G based on the relationship between the angular velocity fluctuation reference Fs and the angular velocity fluctuation reference Fs, for example, the difference between the angular velocity fluctuation reference Fs and the angular velocity fluctuation Fn is defined as the angular velocity fluctuation difference G. 1 deriving means 105a, when the angular velocity variation Fn is greater than the angular velocity variation reference Fs, when the angular velocity variation difference G is 0, and when the angular velocity variation Fn is less than the angular velocity variation reference Fs, The second deriving unit 105 sets a difference between the angular velocity variation reference Fs and the angular velocity variation Fn as the angular velocity variation difference G.
b.

Further, based on the angular velocity fluctuation difference G obtained by the plurality of angular velocity difference deriving means 105, an angular velocity fluctuation difference Da within a predetermined stroke is derived, and based on the angular velocity fluctuation difference Da, the internal combustion engine A misfire judging means 106 for judging a misfire state is provided. The misfire determination means 106 is provided with a fluctuation difference amount deriving means 107, which is based on the angular velocity fluctuation differences G obtained by the plurality of angular velocity difference deriving means 105, and determines the angular velocity fluctuation difference amount within a predetermined stroke. Derive Da. For example, based on the angular velocity fluctuation difference G obtained by the first deriving means and the second deriving means, respectively, and the distribution function Ka, Kb depending on the load and corresponding to each deriving means, the angular velocity fluctuation difference Da is obtained.
Ask for. The angular velocity variation difference reference value Dt required for determination is
The configuration output by the abnormal fluctuation amount deriving means 108 is employed. The determination in the misfire determination means 106 is performed, for example, by the first derivation means 105a or the second derivation means 105a.
If the angular speed variation difference Da derived based on the angular speed variation difference G derived by the deriving means 105b is larger than the angular speed variation difference reference value Dt of the misfire amount to be determined for the internal combustion engine, it is determined that a misfire is abnormal. I do.

On the other hand, as shown in FIG.
06, the angular velocity variation difference Da measured and derived is sent to the reference angular velocity generating means 104. This means uses the angular velocity variation reference Fs in accordance with the misfire determination standard. And a fluctuation amount reference updating means for updating in accordance with the angular velocity fluctuation difference Da. That is, the reference angular velocity generating means 104 has a function as the fluctuation amount reference updating means 109.

Further, as shown in FIG. 1, the misfire detecting apparatus for an internal combustion engine according to the present invention has the angular velocity fluctuation difference Da as a probability function in an operation state that can be regarded as a normal operation state. , And based on the obtained probability distribution of the angular velocity variation difference Da, an angular velocity variation difference reference value Dt for determining an abnormal combustion region.
Is provided. The angular velocity variation difference reference value Dt is a reference value for misfire determination, and a configuration is employed in which the abnormal variation amount derivation means 108 outputs this reference value to the misfire determination means 106.

The above is the configuration of the temporary misfire detection.
In the present application, an operation state quantity of the internal combustion engine corresponding to the misfire frequency (this state quantity is referred to as a misfire quantity in the present application) can also be output. That is, as shown in the rightmost functional block in FIG. 1, a misfire amount estimation reference value deriving unit 110 and a misfire amount estimation reference value derived by the misfire amount estimation reference value deriving unit 110 (this is Actually, the unit misfire average angular velocity variation difference D
m), and derives a misfire amount based on a predetermined standard.
1 is provided.

Here, the misfire amount estimation reference value deriving means 110
Is an average value of the angular velocity variation difference Da in the first operating state that can be regarded as a normal operation state as the first representative value, and the average value of the angular velocity variation difference Da in the second operating state that can be regarded as the misfire operation state, As the second representative value, a unit misfire average angular velocity variation difference Dm, which is a difference between the first representative value and the second representative value, is derived. From the relationship between the unit misfire average angular velocity variation difference Dm and the angular velocity variation difference Da measured in the internal combustion engine in the operating state, the misfire amount is obtained by the misfire amount determination means 111. Further, since the angular velocity variation difference determination reference value Dtf for the preset determination reference misfire amount is obtained from the relationship with the unit misfire average angular velocity variation difference Dm, the misfire amount determination means 111 performs measurement. Angular velocity variation difference Da
Exceeds the angular velocity variation difference determination reference value Dtf,
It is configured to generate misfire information. The above is the schematic block configuration of the device.

The configuration and operation of each means will be described below with reference to FIGS.

(A) Angular velocity measuring means 101 In FIG. 2, 5 is a reference position signal generator, 6 is an angular velocity unit signal generator, and 7 is a power meter (this works as a load condition measuring means). Each of these generators 5 and 6 has time signals Pa and P based on the rotation of the camshaft gear 3 and the crankshaft gear 4 of the engine 1 as shown in FIG.
b. That is, the reference position signal generator 5 outputs the signal Pa corresponding to the gear teeth provided at the reference position of the camshaft gear 3. Similarly, it outputs a signal Pb corresponding to the gear teeth provided on the crankshaft gear 4. The generation of the pulse signal is not always performed as in the present embodiment.
For example, by providing a reference signal generator on the crankshaft as shown in FIG. 4 and further providing an ignition signal detection sensor as shown in FIG.
d signal is generated, and from the Pd signal and the Pa signal, Pa
It is also possible to determine the reference position in the same way as the signal. The signal Pb is a signal corresponding to each crank angle, and by measuring the interval time of each pulse, the instantaneous rotational angular velocity near the angle can be obtained. By making this correspond to the signals Pa and Pd, the rotational angular velocity V corresponding to the rotational angle θ of the engine is obtained.

If the engine is running normally,
As shown in FIG. 6, when the rotational angular velocity V accelerates in a part of the explosion-expansion stroke with respect to the crank angle θ and decelerates in the part of the intake and compression strokes, an abnormal combustion (misfire) occurs. As shown in the figure, the waveform is such that even in the expansion stroke in which a misfire has occurred because the explosion does not occur, the speed is further reduced. The engine for the generator is controlled by a governor or the like so as to rotate at a constant speed. However, since the governor responds slowly to a misfire, it takes a long time to start to recover the rotation. For this reason, the rotation of the engine is maintained in such a manner that it temporarily decreases. However, if the difference from the case of normal rotation is taken as it is, even if the rotation is actually normal, the overall speed is not constant, so the difference may be calculated as a rotation fluctuation difference.

(B) Angular speed fluctuation amount deriving means 102 For this purpose, the obtained rotational angular speed V is further obtained through a moving average number 1 or a low-pass filter in a certain section to obtain an average speed Vav. FIG. 8 shows the average speed in the normal state and the abnormal state. And its average speed V
The angular velocity fluctuation amount Fn is obtained from av by the calculation of (Equation 2).

(Equation 1) Here, n and m are sections for calculating the average speed (for example,
One stroke).

(Equation 2) FIG. 9 is a graph of the rotational speed fluctuation amount Fn obtained in the normal state and the abnormal state. By doing so, Fn (x) does not depend on a slow load change or a difference in rotation speed, but has a speed depending on the engine condition such as a misfire with a fast change speed. This rotation speed fluctuation amount Fn
Is used to calculate the actual misfire data.

C. Reference angular velocity variation generation means 104 First, a signal is input in a state where it is clear that the rotation is normal in advance, and a waveform of the angular velocity variation reference Fs is obtained. Here, since the amount of change varies greatly depending on the load, a reference waveform is actually acquired for each predetermined load. However, in this case, it is necessary to check all the loads. Therefore, actually, a certain amount of loads is checked, and a value obtained by linearly interpolating each load for each Fs is used. For example, if a function Fs (x, La) for a certain load La is used, a function Fs (x, Ln) of the load Ln between another load Lb and the function Fs (x, Lb) is calculated as shown in Expression 3. Is done.

(Equation 3) This angular velocity variation reference Fs is also updated during normal detection, which will be described later.

D. Angular velocity difference deriving means 105 In order to confirm how much the velocity actually fluctuates by using the angular velocity variation reference Fs obtained as described above, the angular velocity variation Fn obtained by measurement must be An angular velocity variation difference G is obtained using an analysis function Gn (fn, fs) between the angular velocity variation standard Fs. In the embodiment, two types of analysis functions Ga and Gb are used.

(Equation 4)

(Equation 5) Here, the analytic function Ga simply obtains the difference from the reference, but the analytic function Gb is a function whose value becomes 0 when the measured value is in an accelerated state from the reference waveform. The analysis function Gb is a function that is normally used when a load is hardly applied. When the rotation depends on the inertia of the engine and the explosive force, and there is almost no difference due to the load change, the load change is slow. The reason for this is to output a value only when the rotation clearly falls below the reference value, since a slight variation causes a greater variation in the integrated value performed thereafter than a variation in the explosive power.

D. Difference amount deriving means 107 The results of the respective analysis functions are collected into one value by load-dependent distribution functions Ka (Ln) and Kb (Ln).

(Equation 6) If the amount of change varies depending on each load,
Misfire can be detected with high accuracy by using a plurality of optimal functions or loads as variables (see FIG. 10). The obtained S (x, Ln) becomes a value of only the portion where the combustion failure or misfire has occurred as shown in FIG.

E. Misfire discriminating means 106 With respect to the angular velocity variation reference Fs, this angular velocity variation difference G is calculated from equation (7), and a result of integration over the stroke is provided with a certain judgment value Dt to determine whether or not the rotation has misfired. Determine.

(Equation 7) F. Fluctuation amount reference updating means 109 After finishing this determination, if there is no misfire in the rotation, the reference waveform (angular velocity fluctuation amount reference Fs) is updated according to a certain function U. As a result, it follows that the rotational angular velocity fluctuation of the engine changes due to a change in the state of the engine or a change over time. For example, if the function U is

(Equation 8) In order to determine the next angular velocity variation reference Fs,

(Equation 9) The update is performed gradually according to the values of Ka and Kb during normal operation, and the update amount is reduced during abnormal rotation (see FIG. 12). By performing the above processing, it is possible to determine poor combustion or misfire.

G. Misfire amount determining means 111 In order to obtain a necessary misfire amount, it is necessary to integrate over each rotation range. Therefore, the rotational angular velocity variation difference D obtained by Expression 10 is obtained for the determined sections a to b.

(Equation 10) Here, the obtained D (x, Ln) is the total amount of the rotational angular velocity fluctuation difference due to poor combustion or misfire in a predetermined rotation range a to b (for example, for one stroke).
Therefore, the rotational angular velocity variation difference Dm due to one misfire
Is obtained, the amount Ms of stall comparable to the misfire occurring in the rotation range a to b is obtained as shown in Expression 11.

[Equation 11] As a result, the misfire amount Mn, which is the number of misfires per stroke,
Is

(Equation 12) Becomes If Mn is 1, it means that all cylinders are in a misfire state.

Now, in order to check whether a state corresponding to misfire or poor combustion has occurred in the rotation, it is necessary to check the value of the angular velocity variation difference Da per stroke. With respect to the discrimination value Dt, the apparatus is calibrated while the engine is rotating normally (first operating state),
First, the value of the angular velocity variation difference Da in this state is sampled, the standard deviation thereof is set to σ, and the probability distribution function is set to a normal distribution. Can be reduced to about 2% of the normal rotation. Therefore, if a value exceeding the angular velocity variation difference reference value Dt occurs, it can be considered that misfire or combustion failure has occurred in the process.

G Misfire amount estimation reference value deriving means 110 Further, the apparatus is calibrated in a state where a misfire occurs due to a forced misfire (second operation state), and D is obtained from the result.
m can be obtained (see FIG. 13). Here, the unit misfire average angular velocity variation difference Dm is defined as a first representative value of the average value of the angular velocity variation difference Da in the first operation state which can be regarded as a normal operation state, and the second misfire operation state can be regarded as a forced misfire operation state.
The average value of the angular velocity variation difference Da in the operating state is
The second representative value can be obtained as a difference between the first representative value and the second representative value. In this case, the forced misfire occurs in a multi-cylinder engine in a state where one cylinder is misfired. Further, in the above-mentioned determination means,
Determination reference value Dt for difference in angular velocity variation with respect to determination reference misfire amount
f may be obtained from the unit misfire average angular velocity variation difference Dm, and misfire information may be generated when the measured angular velocity variation difference Da exceeds the angular velocity variation difference determination reference value Dtf. For example, if the reference criterion misfire is one misfire during n strokes, the angular velocity variation difference criterion Dtf in the rotation ranges a to b is obtained as in Expression 13.

[0027]

(Equation 13) That is, by adopting such a configuration, it is possible to detect a misfire, derive a misfire amount (misfire frequency), and output an alarm signal when the designated misfire amount is reached.

[0028]

According to the present invention, by using an existing sensor and subjecting the sensor output to a predetermined signal processing,
It is possible to provide a misfire detection device that can determine a combustion failure and misfire of an engine and measure the frequency of occurrence.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a misfire detection device of the present application.

FIG. 2 is a diagram showing a rotation angular velocity and rotation angle detection system;

FIG. 3 is a diagram showing a state of a detection signal.

FIG. 4 is a diagram showing a further rotation angular velocity and rotation angle detection system;

FIG. 5 is a diagram showing a state of a further detection signal;

FIG. 6 is a diagram showing a state of a rotational angular velocity V with respect to a crank angle in a normal operation state.

FIG. 7 is a diagram showing a state of a rotational angular velocity V with respect to a crank angle in an abnormal state;

FIG. 8 is a diagram showing a state of a rotational angular velocity V and a moving average velocity in an abnormal state;

FIG. 9 is a diagram showing a state of an angular velocity fluctuation amount F with respect to a crank angle in an abnormal state;

FIG. 10 is an explanatory diagram of a derivation sequence of an angular velocity variation difference Da.

FIG. 11 is a diagram showing a state of an angular velocity variation difference G with respect to a crank angle in an abnormal state;

FIG. 12 is an explanatory diagram of an update sequence of an angular velocity variation reference Fs.

FIG. 13 is a diagram showing an appearance probability distribution of the angular velocity variation difference Da in a normal operation state and an abnormal operation state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine (internal combustion engine) 3 Camshaft gear (rotating shaft) 4 Crankshaft gear (rotating shaft) 5 Reference position signal generator 6 Angular velocity unit signal generator 7 Wattmeter 100 Misfire detection device 101 Angular velocity measuring means 102 Derivation of angular velocity fluctuation amount Means 103 Load status measuring means 104 Reference angular velocity fluctuation amount generating means 105 Angular velocity difference deriving means 105a First deriving means 105b Second deriving means 106 Misfire discriminating means 107 Fluctuation difference amount deriving means 108 Abnormal fluctuation amount deriving means 109 Variation amount reference updating means 110 Misfire amount estimation reference value deriving means 111 Misfire amount determining means

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[Procedure amendment]

[Submission date] February 7, 2000 (2000.2.7)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

Patent application title: Method and apparatus for detecting misfire of an internal combustion engine

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to detecting a combustion failure and misfire of a multi-cylinder internal combustion engine for power generation.

[0002]

2. Description of the Related Art As a conventional device for detecting misfire of an internal combustion engine, a special sensor is attached to detect a combustion state,
There is a type in which a temperature sensor is attached near the exhaust port to determine a decrease in exhaust temperature at the time of misfire, or a type in which misfire is detected by detecting rotation fluctuation and detecting a decrease in rotation speed.

[0003]

According to the above-mentioned prior art, In the rotation fluctuation detection type misfire detection device, when the rotation angular velocity changes due to factors such as load fluctuation other than misfire,
This may be erroneously detected. 2. When a certain degree of operation is possible even when a misfire has occurred, as in the case of a generator engine, urgently stopping the engine and recovering from the failure lacks stability of power supply. In other words, it is necessary to rationally set the criteria. However, in a state where an engine failure or an accident occurs, the engine must be stopped even if the power supply is stopped. For this reason, an amount indicating the degree of misfire such as misfire or poor combustion (referred to as misfire amount in the present application)
It is necessary to use a value that depends on the explosive power of each cylinder as much as possible. If the absolute value of the rotation fluctuation is simply used, the explosive power normally generated for each load differs, so that the misfire amount cannot be directly estimated from the fluctuation amount. 3. In the rotation fluctuation detection, the tendency of the rotation fluctuation of the engine differs depending on the state of the load. Therefore, when the rotation fluctuation is detected by one method, the accuracy is good for one load, but may be poor for another load. This is because the rotational characteristics of the engine change depending on the load of the engine.
Also, a change in the engine speed affects the load side and further changes the load. For this reason, there is a drawback that the parameters required by the fixed analysis method alone become too large and it is difficult to cope with them.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a low-cost and accurate engine abnormal combustion and misfire by utilizing a rotational speed detection sensor and the like and a generated power signal used in an electronically controlled engine. It is an object of the present invention to provide a misfire detection device capable of measuring and determining the misfire.

[0005]

In order to achieve this object, the characteristic structure of the method for detecting misfire of an internal combustion engine according to the present invention is as follows.
As described in claim 1, the rotation angular velocity of the output shaft of the internal combustion engine, in response to the rotation angle of the measured each time point, the waves
With measured as a form, the to the rotational angular velocity to be measured, and the difference of angular speed variation Fn with the average angular velocity of a certain period of measurement time before measuring the rotation angular velocity, normal
In a state where it is clear that the rotation is accurate, the angular velocity fluctuation reference Fs previously obtained as a waveform corresponding to the rotation angle of the output shaft at each measurement time point and the angular velocity derived at each measurement time point The angular velocity variation difference G is derived based on the variation amount Fn and the derived angular velocity variation difference G
, An angular velocity variation difference Da within a predetermined stroke is derived, and based on the angular velocity variation difference Da,
A misfire detection method for an internal combustion engine that determines a misfire state of an internal combustion engine, wherein the angular velocity fluctuation difference Da is detected a plurality of times in a first operation state that can be regarded as a normal operation state, and the angular velocity fluctuation difference Da is defined as a probability function. The angular velocity variation difference D
a as a first probability distribution, and based on the obtained first probability distribution of the angular velocity variation difference Da, an angular velocity variation difference reference value Dt for determining an abnormal combustion region is set. A misfire of the internal combustion engine is detected based on the fluctuation difference amount reference value Dt. When adopting this approach, as a discrimination indication of misfire adopted angular speed variation difference amount, performs operation of the internal combustion engine in advance the normal operating condition, the statistical of the resulting angular speed variation difference amount Da in this operating condition The data is regarded as a random variable, and if its occurrence probability is very low, it is considered that an abnormality has occurred. By doing so, misfire detection that matches the actual situation of the internal combustion engine to be detected can be performed. In this case, when deriving the angular velocity fluctuation difference Da, as shown in an embodiment described later, it is assumed that abnormal fluctuations are detected and discriminated except angular velocity fluctuations due to load fluctuations applied to the internal combustion engine. , The reliability of the determination can be improved.

As a device for determining misfire of an internal combustion engine by such a method, the rotation angular velocity of the output shaft of the internal combustion engine corresponds to the rotation angle at each measurement time. And measure it as a waveform ,
The angular velocity fluctuation deriving means for deriving the difference between the measured rotational angular velocity and the average rotational angular velocity for a certain period before the measurement time point for measuring the rotational angular velocity as the angular velocity fluctuation Fn, and the angular velocity fluctuation deriving means, Normal rotation
In a state where it is clear that the angular velocity fluctuation reference Fs obtained in advance as a waveform corresponding to the rotation angle of the output shaft at each measurement point in time and the angular velocity fluctuation amount Fn derived at each measurement point in time, And an angular velocity difference deriving means for deriving an angular velocity variation difference G, and an angular velocity variation difference Da within a predetermined stroke, based on the angular velocity variation difference G derived by the angular velocity difference deriving means. A misfire detection device for an internal combustion engine including a misfire determining means for determining a misfire state of the internal combustion engine based on the angular velocity variation difference Da, in a first operation state that can be regarded as a normal operation state;
The angular velocity variation difference Da for determining the abnormal combustion region based on the probability distribution of the angular velocity variation difference Da obtained by using the angular velocity variation difference Da as a probability function, and determining the probability distribution of the angular velocity variation difference Da. The object can be achieved by setting the reference value Dt and configuring the misfire determination means to detect the misfire of the internal combustion engine based on the angular velocity variation difference reference value Dt.

In order to achieve the above object, a method for detecting a misfire of an internal combustion engine according to the present invention is characterized in that the rotational angular velocity of the output shaft of the internal combustion engine is determined by the following method.
Corresponding to the rotation angle at each time point of the measurement, the rotation angle is measured as a waveform, and the difference between the measured rotation angular velocity and the average rotation angular velocity for a certain period before the measurement time point at which the rotation angular velocity is measured is an angular velocity variation Fn And normal rotation
In the state where is clear, the angular velocity fluctuation reference Fs previously obtained as a waveform and the angular velocity fluctuation Fn derived at each measurement point, corresponding to the rotation angle of the output shaft at each measurement point in time. Based on the angular velocity fluctuation difference G, and based on the derived angular velocity fluctuation difference G, to derive the angular velocity fluctuation difference Da within a predetermined stroke, and based on the angular velocity fluctuation difference Da, A misfire detection method for an internal combustion engine for determining a misfire state of an internal combustion engine, wherein the angular velocity change difference Da is detected a plurality of times in a first operation state that can be regarded as a normal operation state, and the angular velocity change difference D is detected.
a first representative value that is a representative value (e.g., an average value) of the angular velocity fluctuation difference Da is detected a plurality of times in a second operation state that can be regarded as a forced misfire operation state. A second representative value that is a representative value (for example, an average value) is obtained, and a unit misfire average angular velocity variation difference Dm that is a difference between the first representative value and the second representative value is measured in the internal combustion engine in an operating state. Angular velocity variation difference Da
And the amount of misfire is determined from the relationship. In this method, the amount defined as the misfire amount can be called a misfire frequency, and such a misfire amount is not conventionally known. In this method, a statistical distribution of the angular velocity fluctuation difference Da in the first operating state is obtained, and for example,
The average value is obtained as a first representative value. The first representative value is an angular velocity fluctuation difference obtained from rotation fluctuation that occurs when the engine is in a normal operation state. On the other hand, the statistical distribution of the angular velocity variation difference Da in the second operating state is determined, and, for example, its average value is determined as the second representative value. The second representative value is an angular velocity variation difference amount obtained from rotation variation that occurs when the engine generates a unit misfire.
For example, in a multi-cylinder internal combustion engine, this data is obtained by forcibly misfiring a single cylinder, collecting data in that state, and calculating the average value of the angular velocity variation difference. Can be. Here, the difference between the first representative value and the second representative value can be regarded as the unit misfire average angular velocity variation difference Dm.
And the angular velocity variation difference Da measured in the internal combustion engine in the operating state (for example, the ratio thereof), this value becomes a value representing the misfire frequency. By knowing the amount of misfire in this way, it is possible to evaluate the misfire state of the engine and determine misfire based on the misfire standard.

According to a fifth aspect of the present invention, there is provided a misfire determining apparatus for determining the amount of misfire by determining a rotational angular velocity of an output shaft of an internal combustion engine in accordance with a rotational angle at each measurement time. An angular velocity variation deriving means for measuring as a waveform, deriving, as an angular velocity variation Fn, a difference between the measured rotational angular velocity and an average rotational angular velocity for a certain period before a measurement time point at which the rotational angular velocity is measured; It is clear that the rotation is normal by the fluctuation derivation means.
In state, the measurement in response to the rotation angle of the output shaft of each time point, the waves
An angular velocity variation reference Fs previously obtained as a shape ;
An angular velocity difference deriving unit that derives an angular velocity variation difference G based on the angular velocity variation amount Fn derived at each measurement point in time, and a predetermined angular velocity difference G derived by the angular velocity difference deriving unit. A misfire detection device for an internal combustion engine, comprising: misfire determination means for determining a misfire state of an internal combustion engine based on the angular speed variation difference Da while deriving an angular speed variation difference Da within a stroke. The angular velocity variation difference D in the first operating state which can be regarded as a state
The first representative value and the second representative value are referred to as a first representative value and a representative value of the angular velocity variation difference Da in a second operating state that can be regarded as a forced misfire operation state. And the unit misfire average angular velocity variation difference Dm,
It can be provided with a misfire amount discriminating means for obtaining a misfire amount from the relationship with the angular velocity fluctuation difference Da measured in the internal combustion engine in the operating state.

In the case where the misfire amount is obtained as described above, as set forth in claim 3, the angular velocity variation difference amount reference value Dtf with respect to the reference misfire amount is calculated by calculating the unit misfire average angular velocity. It is preferable that misfire information is generated when the angular velocity variation difference Da measured in advance from the variation difference Dm exceeds the angular velocity variation difference determination reference value Dtf. By doing so, the misfire determination can be performed with a relatively simple configuration on a reasonable basis. According to an apparatus configuration corresponding to this configuration, an angular velocity variation difference determination reference value Dtf with respect to a determination reference misfire amount is obtained from the unit misfire average angular velocity variation difference amount Dm and measured. Angular velocity fluctuation difference Da
However, when misfire exceeds the angular velocity variation difference determination reference value Dtf, misfire information is generated, so that a misfire detection device for an internal combustion engine having a desired configuration in the present application can be obtained.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a misfire detection device 10 according to the present invention.
0 is a functional block diagram. As shown in FIG. 1, the misfire detection device 100 includes an angular velocity measuring unit 101 that measures a rotational angular velocity of an output shaft of an internal combustion engine in accordance with a rotational angle at each measurement time point, and a measurement that measures the rotational angular velocity. Mean rotational angular velocity for a certain period before the time and the angular velocity measuring means 1
The angular velocity fluctuation deriving means 102 derives the difference from the rotational angular velocity measured by the above-mentioned method as the angular velocity fluctuation Fn at each measurement time, and measures the output of the internal combustion engine at each measurement time from the generated power. Load condition measuring means 10
3 is provided as a main measurement system. In addition, normal
In a state where the rotation is apparent, the reference angular velocity fluctuation generating means 104 generates an angular velocity fluctuation reference Fs which is obtained in advance corresponding to the rotation angle of the output shaft at each time point of the measurement.
And an angular velocity difference deriving means 105 for calculating an angular velocity variation difference G based on the angular velocity variation reference Fs and the angular velocity variation Fn derived by the angular velocity variation deriving means 104 at each measurement time. Have multiple. The angular velocity difference deriving unit 105 includes a plurality of such units, based on a relationship between the angular velocity variation Fn measured in a preset rotation range and the angular velocity variation reference Fs. The angular velocity variation difference G
For example, a first deriving unit 105a that sets the difference between the angular velocity fluctuation reference Fs and the angular velocity fluctuation Fn to the angular velocity fluctuation difference G, and calculates the angular velocity fluctuation Fn as the angular velocity fluctuation reference Fs If the angular velocity fluctuation difference G is 0, the angular velocity fluctuation difference G is 0, and if the angular velocity fluctuation Fn is smaller than the angular velocity fluctuation reference Fs, the difference between the angular velocity fluctuation reference Fs and the angular velocity fluctuation Fn is calculated as: A second deriving unit 105b for setting the angular velocity variation difference G.

Further, based on the angular velocity fluctuation difference G obtained by the plurality of angular velocity difference deriving means 105, an angular velocity fluctuation difference Da within a predetermined stroke is derived, and based on the angular velocity fluctuation difference Da, the internal combustion engine A misfire judging means 106 for judging a misfire state is provided. The misfire determination means 106 is provided with a fluctuation difference amount deriving means 107, which is based on the angular velocity fluctuation differences G obtained by the plurality of angular velocity difference deriving means 105, and determines the angular velocity fluctuation difference amount within a predetermined stroke. Derive Da. For example, based on the angular velocity fluctuation difference G obtained by the first deriving means and the second deriving means, respectively, and the distribution function Ka, Kb depending on the load and corresponding to each deriving means, the angular velocity fluctuation difference Da is obtained.
Ask for. The angular velocity variation difference reference value Dt required for determination is
The configuration output by the abnormal fluctuation amount deriving means 108 is employed. The determination in the misfire determination means 106 is performed, for example, by the first derivation means 105a or the second derivation means 105a.
If the angular speed variation difference Da derived based on the angular speed variation difference G derived by the deriving means 105b is larger than the angular speed variation difference reference value Dt of the misfire amount to be determined for the internal combustion engine, it is determined that a misfire is abnormal. I do.

On the other hand, as shown in FIG.
06, the angular velocity variation difference Da measured and derived is sent to the reference angular velocity generating means 104. This means uses the angular velocity variation reference Fs in accordance with the misfire determination standard. And a fluctuation amount reference updating means for updating in accordance with the angular velocity fluctuation difference Da. That is, the reference angular velocity generating means 104 has a function as the fluctuation amount reference updating means 109.

Further, as shown in FIG. 1, the misfire detecting apparatus for an internal combustion engine according to the present invention has the angular velocity fluctuation difference Da as a probability function in an operation state that can be regarded as a normal operation state. , And based on the obtained probability distribution of the angular velocity variation difference Da, an angular velocity variation difference reference value Dt for determining an abnormal combustion region.
Is provided. The angular velocity variation difference reference value Dt is a reference value for misfire determination, and a configuration is employed in which the abnormal variation amount derivation means 108 outputs this reference value to the misfire determination means 106.

The above is the configuration of the temporary misfire detection.
In the present application, an operation state quantity of the internal combustion engine corresponding to the misfire frequency (this state quantity is referred to as a misfire quantity in the present application) can also be output. That is, as shown in the rightmost functional block in FIG. 1, a misfire amount estimation reference value deriving unit 110 and a misfire amount estimation reference value derived by the misfire amount estimation reference value deriving unit 110 (this is Actually, the unit misfire average angular velocity variation difference D
m), and derives a misfire amount based on a predetermined standard.
1 is provided.

Here, the misfire amount estimation reference value deriving means 110
Is an average value of the angular velocity variation difference Da in the first operating state that can be regarded as a normal operation state as the first representative value, and the average value of the angular velocity variation difference Da in the second operating state that can be regarded as the misfire operation state, As the second representative value, a unit misfire average angular velocity variation difference Dm, which is a difference between the first representative value and the second representative value, is derived. From the relationship between the unit misfire average angular velocity variation difference Dm and the angular velocity variation difference Da measured in the internal combustion engine in the operating state, the misfire amount is obtained by the misfire amount determination means 111. Further, since the angular velocity variation difference determination reference value Dtf for the preset determination reference misfire amount is obtained from the relationship with the unit misfire average angular velocity variation difference Dm, the misfire amount determination means 111 performs measurement. Angular velocity variation difference Da
Exceeds the angular velocity variation difference determination reference value Dtf,
It is configured to generate misfire information. The above is the schematic block configuration of the device.

The configuration and operation of each means will be described below with reference to FIGS.

(A) Angular velocity measuring means 101 In FIG. 2, 5 is a reference position signal generator, 6 is an angular velocity unit signal generator, and 7 is a power meter (this works as a load condition measuring means). Each of these generators 5 and 6 has time signals Pa and P based on the rotation of the camshaft gear 3 and the crankshaft gear 4 of the engine 1 as shown in FIG.
b. That is, the reference position signal generator 5 outputs the signal Pa corresponding to the gear teeth provided at the reference position of the camshaft gear 3. Similarly, it outputs a signal Pb corresponding to the gear teeth provided on the crankshaft gear 4. The generation of the pulse signal is not always performed as in the present embodiment.
For example, by providing a reference signal generator on the crankshaft as shown in FIG. 4 and further providing an ignition signal detection sensor as shown in FIG.
d signal is generated, and from the Pd signal and the Pa signal, Pa
It is also possible to determine the reference position in the same way as the signal. The signal Pb is a signal corresponding to each crank angle, and by measuring the interval time of each pulse, the instantaneous rotational angular velocity near the angle can be obtained. By making this correspond to the signals Pa and Pd, the rotational angular velocity V corresponding to the rotational angle θ of the engine is obtained.

If the engine is running normally,
As shown in FIG. 6, when the rotational angular velocity V accelerates in a part of the explosion-expansion stroke with respect to the crank angle θ and decelerates in the part of the intake and compression strokes, an abnormal combustion (misfire) occurs. As shown in the figure, the waveform is such that even in the expansion stroke in which a misfire has occurred because the explosion does not occur, the speed is further reduced. The engine for the generator is controlled by a governor or the like so as to rotate at a constant speed. However, since the governor responds slowly to a misfire, it takes a long time to start to recover the rotation. For this reason, the rotation of the engine is maintained in such a manner that it temporarily decreases. However, if the difference from the case of normal rotation is taken as it is, even if the rotation is actually normal, the overall speed is not constant, so the difference may be calculated as a rotation fluctuation difference.

(B) Angular velocity fluctuation amount deriving means 102 For this reason, the obtained rotational angular velocity V is further subjected to moving averaging ( Equation 1 ) or a low-pass filter in a certain section.
An average speed Vav is obtained. FIG. 8 shows the average speed in the normal state and the abnormal state. Then, the angular velocity variation Fn is obtained from the average velocity Vav by calculation of (Equation 2).

(Equation 1) Here, n and m are sections for calculating the average speed (for example,
(For one stroke).

(Equation 2) Figure 9 is the angular speed variation Fn graph obtained when the state of the normal state and abnormal. By doing so, Fn (x) does not depend on a slow load change or a difference in rotation speed, but has a speed depending on the engine condition such as a misfire with a fast change speed. With this angular speed variation Fn, it calculates the actual misfire data.

C. Reference angular velocity variation generation means 104 First, a signal is input in a state where it is clear that the rotation is normal in advance, and a waveform of the angular velocity variation reference Fs is obtained. Here, since the amount of change varies greatly depending on the load, a reference waveform is actually acquired for each predetermined load. However, in this case, it is necessary to check all the loads. Therefore, actually, a certain amount of loads is checked, and a value obtained by linearly interpolating each load for each Fs is used. For example, if a function Fs (x, La) for a certain load La is used, a function Fs (x, Ln) of the load Ln between another load Lb and the function Fs (x, Lb) is calculated as shown in Expression 3. Is done.

(Equation 3) This angular velocity variation reference Fs is also updated during normal detection, which will be described later.

D. Angular velocity difference deriving means 105 In order to confirm how much the velocity actually fluctuates by using the angular velocity variation reference Fs obtained as described above, the angular velocity variation Fn obtained by measurement must be An angular velocity variation difference G is obtained using an analysis function Gn located between the angular velocity variation standard Fs. In the embodiment, the analysis functions Ga and Gb
Use the type.

(Equation 4)

(Equation 5) Here, the analytic function Ga simply obtains the difference from the reference, but the analytic function Gb is a function whose value becomes 0 when the measured value is in an accelerated state from the reference waveform. The analysis function Gb is a function that is normally used when a load is hardly applied. When the rotation depends on the inertia of the engine and the explosive force, and there is almost no difference due to the load change, the load change is slow. The reason for this is to output a value only when the rotation clearly falls below the reference value, since a slight variation causes a greater variation in the integrated value performed thereafter than a variation in the explosive power.

D. Difference amount deriving means 107 The results of the respective analysis functions are collected into one value by load-dependent distribution functions Ka (Ln) and Kb (Ln).

(Equation 6) If the amount of change varies depending on each load,
It is possible to accurately detect the misfire by using those multiple optimal functional or load as a variable (see Figure 10). The obtained S (x, Ln) becomes a value of only the portion where the combustion failure or misfire has occurred as shown in FIG.

[0023] For E misfire discriminating means 106 the angular speed fluctuation amount reference Fs, results the angular velocity variation difference G calculated from Equation 7, by integrating its stroke, the angular velocity
A certain determination value Dt is provided for the degree variation difference Da, and it is determined whether or not a misfire has occurred in the rotation.

(Equation 7) F. Fluctuation amount reference updating means 109 After finishing this determination, if there is no misfire in the rotation, the reference waveform (angular velocity fluctuation amount reference Fs) is updated according to a certain function U. As a result, it follows that the rotational angular velocity fluctuation of the engine changes due to a change in the state of the engine or a change over time. For example, if the function U is

(Equation 8) In order to determine the next angular velocity variation reference Fs,

(Equation 9) The update is performed gradually according to the values of Ka and Kb during normal operation, and the update amount is reduced during abnormal rotation (see FIG. 12). By performing the above processing, it is possible to determine poor combustion or misfire.

G. Misfire amount determining means 111 In order to obtain a necessary misfire amount, it is necessary to integrate over each rotation range. So determined Ru angular speed variation difference amount D of the number 10 for up to a defined interval a~b is obtained.

(Equation 10) Here, the D (x, Ln) to obtain, there-determined rotation range to b (e.g., one stroke min) is the total amount of by that angular speed variation difference poor combustion or misfires in. Thus, if been obtained it is by that corner speed variation difference amount Dm to misfire of per, the amount Ms of the stall comparable to misfire that occurred to the rotational range a~b is determined to like the number 11.

[Equation 11] As a result, the misfire amount Mn, which is the number of misfires per stroke,
Is

(Equation 12) Becomes If Mn is 1, it means that all cylinders are in a misfire state.

Now, in order to check whether a state corresponding to misfire or poor combustion has occurred in the rotation, it is necessary to check the value of the angular velocity variation difference Da per stroke. With respect to the discrimination value Dt, the apparatus is calibrated while the engine is rotating normally (first operating state),
First, the value of the angular velocity variation difference Da in this state is sampled, the standard deviation thereof is set to σ, and the probability distribution function is set to a normal distribution. Can be reduced to about 2% of the normal rotation. Therefore, if a value exceeding the angular velocity variation difference reference value Dt occurs, it can be considered that misfire or combustion failure has occurred in the process.

G Misfire amount estimation reference value deriving means 110 Further, the apparatus is calibrated in a state where a misfire occurs due to a forced misfire (second operation state), and D is obtained from the result.
m can be obtained (see FIG. 13). Here, the unit misfire average angular velocity variation difference Dm is defined as a first representative value of the average value of the angular velocity variation difference Da in the first operation state which can be regarded as a normal operation state, and the second misfire operation state can be regarded as a forced misfire operation state.
The average value of the angular velocity variation difference Da in the operating state is
The second representative value can be obtained as a difference between the first representative value and the second representative value. In this case, the forced misfire occurs in a multi-cylinder engine in a state where one cylinder is misfired. Further, in the above-mentioned determination means,
Determination reference value Dt for difference in angular velocity variation with respect to determination reference misfire amount
f may be obtained from the unit misfire average angular velocity variation difference Dm, and misfire information may be generated when the measured angular velocity variation difference Da exceeds the angular velocity variation difference determination reference value Dtf. For example, if the reference criterion misfire is one misfire during n strokes, the angular velocity variation difference criterion Dtf in the rotation ranges a to b is obtained as in Expression 13.

[0027]

(Equation 13) That is, by adopting such a configuration, it is possible to detect a misfire, derive a misfire amount (misfire frequency), and output an alarm signal when the designated misfire amount is reached.

[0028]

According to the present invention, by using an existing sensor and subjecting the sensor output to a predetermined signal processing,
It is possible to provide a misfire detection device that can determine a combustion failure and misfire of an engine and measure the frequency of occurrence.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a misfire detection device of the present application.

FIG. 2 is a diagram showing a rotation angular velocity and rotation angle detection system;

FIG. 3 is a diagram showing a state of a detection signal.

FIG. 4 is a diagram showing a further rotation angular velocity and rotation angle detection system;

FIG. 5 is a diagram showing a state of a further detection signal;

FIG. 6 is a diagram showing a state of a rotational angular velocity V with respect to a crank angle in a normal operation state.

FIG. 7 is a diagram showing a state of a rotational angular velocity V with respect to a crank angle in an abnormal state;

FIG. 8 is a diagram showing a state of a rotational angular velocity V and a moving average velocity in an abnormal state;

FIG. 9 is a diagram showing a state of an angular velocity fluctuation amount Fn with respect to a crank angle in an abnormal state;

FIG. 10 is an explanatory diagram of a derivation sequence of an angular velocity variation difference Da.

FIG. 11 is a diagram showing a state of an angular velocity variation difference with respect to a crank angle in an abnormal state;

FIG. 12 is an explanatory diagram of an update sequence of an angular velocity variation reference Fs.

FIG. 13 is a diagram showing an appearance probability distribution of the angular velocity variation difference Da in a normal operation state and an abnormal operation state.

[Description of Signs] 1 Engine (internal combustion engine) 3 Camshaft gear (rotating shaft) 4 Crankshaft gear (rotating shaft) 5 Reference position signal generator 6 Angular velocity unit signal generator 7 Wattmeter 100 Misfire detecting device 101 Angular velocity measuring means 102 angular velocity variation deriving means 103 load situation measuring means 104 reference angular velocity variation generating means 105 angular velocity difference deriving means 105a first deriving means 105b second deriving means 106 misfire discriminating means 107 variation difference deriving means 108 abnormal variation deriving means 109 Fluctuation reference updating means 110 Misfire estimation reference value deriving means 111 Misfire discrimination means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuchika Furukawa 4-1-2, Hirano-cho, Chuo-ku, Osaka City, Osaka Prefecture Inside Osaka Gas Co., Ltd. (72) Tomohiro Ueno Inventor Tomohiro Ueno, Chuo-ku, Osaka City, Osaka Prefecture 1-2 1-2 Osaka Gas Co., Ltd. (72) Inventor Yusuke Fujita 1576-22 Nakahiro, Ako-shi, Hyogo F-term (reference) 3G084 AA00 DA27 EA07 EA11 EB22 FA18 FA24 FA33 FA34 FA38 FA39

Claims (6)

[Claims] 1. A method for measuring a rotational angular velocity of an output shaft of an internal combustion engine in accordance with a rotational angle at each time of measurement, the rotational angular velocity to be measured, and a certain period before a measurement time to measure the rotational angular velocity. The angular velocity variation Fn is defined as the difference between the average angular velocity and the average rotational angular velocity, and the angular velocity variation reference Fs determined in advance corresponding to the rotation angle of the output shaft at each measurement point in time and the angular velocity derived at each measurement point The angular velocity fluctuation difference G is derived on the basis of the fluctuation amount Fn, and the angular velocity fluctuation difference Da within a predetermined stroke is derived on the basis of the derived angular velocity fluctuation difference G. A misfire detection method for an internal combustion engine that determines a misfire state of the internal combustion engine based on the angular velocity fluctuation difference Da in a first operation state that can be regarded as a normal operation state. A probability distribution of the angular velocity fluctuation difference Da using the angular velocity fluctuation difference Da as a probability function is obtained as a first probability distribution, and an abnormal combustion region is determined based on the obtained first probability distribution of the angular velocity fluctuation difference Da. Of detecting the misfire of the internal combustion engine based on the angular velocity variation difference reference value Dt for detecting the misfire of the internal combustion engine based on the angular velocity variation difference reference value Dt. 2. A method for measuring a rotational angular velocity of an output shaft of an internal combustion engine corresponding to a rotational angle at each time of the measurement, the rotational angular velocity to be measured, and a certain period before the measurement time to measure the rotational angular velocity. The angular velocity variation Fn is defined as the difference between the average angular velocity and the average rotational angular velocity, and the angular velocity variation reference Fs determined in advance corresponding to the rotation angle of the output shaft at each measurement point in time and the angular velocity derived at each measurement point The angular velocity fluctuation difference G is derived on the basis of the fluctuation amount Fn, the angular velocity fluctuation difference Da within a predetermined stroke is derived based on the derived angular velocity fluctuation difference G, and the angular velocity fluctuation difference Da is calculated. A misfire detection method for an internal combustion engine that determines a misfire state of the internal combustion engine based on the angular velocity fluctuation difference Da in a first operation state that can be regarded as a normal operation state. A first representative value that is a representative value of the angular velocity variation difference Da is obtained. In the second operating state that can be regarded as a forced misfire operation state, the angular velocity variation difference Da is detected a plurality of times. A second representative value that is a value, a unit misfire average angular velocity variation difference Dm that is a difference between the first representative value and the second representative value, and an angular velocity variation difference measured in the internal combustion engine in an operating state. A method for detecting a misfire of an internal combustion engine, which obtains a misfire amount from a relationship with Da. 3. The angular velocity variation difference Dtf for the determination standard misfire quantity is determined in advance from the unit misfire average angular velocity variation difference Dm, and the measured angular velocity variation difference Dt is calculated.
3. The misfire detection method for an internal combustion engine according to claim 2, wherein misfire information is generated when a exceeds the angular velocity variation difference determination reference value Dtf. 4. A method for measuring a rotational angular velocity of an output shaft of an internal combustion engine corresponding to a rotational angle at each measurement time, and measuring the measured rotational angular velocity and a predetermined period before the measurement time at which the rotational angular velocity is measured. Angular velocity fluctuation deriving means for deriving a difference from the average rotational angular velocity of the output shaft as an angular velocity fluctuation Fn; and an angular velocity previously obtained by the angular velocity fluctuation deriving means corresponding to the rotation angle of the output shaft at each measurement point An angular velocity difference deriving unit that derives an angular velocity variation difference G based on the variation amount reference Fs and the angular velocity variation Fn derived at each measurement point in time; and the angular velocity variation difference derived by the angular velocity difference deriving unit. G, the angular velocity fluctuation difference Da within a predetermined stroke.
And a misfire detection device for an internal combustion engine including misfire determination means for determining a misfire state of the internal combustion engine based on the angular velocity variation difference Da. In a first operation state that can be regarded as a normal operation state, Calculate the probability distribution of the angular velocity fluctuation difference Da using the angular velocity fluctuation difference Da as a probability function, and determine the abnormal velocity region based on the calculated probability distribution of the angular velocity fluctuation difference Da. An apparatus for detecting a misfire in an internal combustion engine, wherein a misfire determination means detects misfire of the internal combustion engine based on the angular velocity variation difference reference value Dt while setting a reference value Dt. 5. A method for measuring a rotational angular velocity of an output shaft of an internal combustion engine corresponding to a rotational angle at each measurement time, and measuring the measured rotational angular velocity and a predetermined period before the measurement time for measuring the rotational angular velocity. Angular velocity variation deriving means for deriving a difference from the average rotational angular velocity of the rotation speed as an angular velocity variation Fn; and an angular velocity previously determined by the angular velocity variation deriving means corresponding to the rotation angle of the output shaft at each measurement time point. An angular velocity difference deriving unit that derives an angular velocity variation difference G based on the variation amount reference Fs and the angular velocity variation Fn derived at each measurement point in time; and the angular velocity variation difference derived by the angular velocity difference deriving unit. G, the angular velocity fluctuation difference Da within a predetermined stroke.
And a misfire detection device for the internal combustion engine, comprising misfire determination means for determining a misfire state of the internal combustion engine based on the angular velocity variation difference Da, wherein the misfire detection device in a first operation state that can be regarded as a normal operation state A representative value of the angular velocity variation difference Da is a first representative value, and a representative value of the angular velocity variation difference Da in a second operating state that can be regarded as a forced misfire operation state is a second representative value. A misfire amount discriminating means for obtaining a misfire amount from a relationship between a unit misfire average angular velocity change amount Dm which is a difference with the second representative value and an angular speed change amount Da measured in the internal combustion engine in an operating state is provided. Misfire detection device for internal combustion engine 6. An angular velocity variation difference determination reference value Dtf for a determination reference misfire amount is obtained from the unit misfire average angular velocity variation difference Dm, and the measured angular velocity variation difference Da is determined by the angular velocity variation difference determination reference value. 6. The misfire detection device for an internal combustion engine according to claim 5, wherein misfire information is generated when Dtf is exceeded.