JPH06221215A - Combustion state detection device and combustion control device for internal combustion engine - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a combustion state detection device capable of accurately detecting the combustion state of an internal combustion engine without requiring special timing control and even during a transition. [Structure] Using a representative pattern read from a representative rotation fluctuation table group 10 and an orthonormal pattern of this representative pattern, multiplication and integration are performed in blocks 13 and 17, and a table search is performed in block 18 to perform combustion of an internal combustion engine. A combustion index that indicates the state is obtained. [Effect] By using the representative pattern of rotational fluctuation and its orthonormal pattern and summing the product of these and the rotational speed fluctuation of the output shaft, the phase difference at the time of detecting the combustion state is absorbed. You can Therefore, the combustion state can be detected without considering the special timing for that. Further, at this time, by setting a representative pattern of the rotational fluctuation for each rotational speed, the combustion state can be easily detected even during a transition, and a separate means for detecting the transition state can be omitted. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for determining in real time the combustion state of an internal combustion engine such as a reciprocating engine that intermittently explodes (combusts). The present invention relates to a combustion state detection device suitable for suppression control.

[0002]

2. Description of the Related Art In an internal combustion engine such as a gasoline engine (hereinafter, simply referred to as an engine), its combustion state greatly affects the driving performance such as efficiency and exhaust gas components. Therefore, if the combustion state can be judged in real time, it is A significant improvement in driving performance can be expected by reflecting this in control.

Therefore, in JP-A-60-13938, in a reciprocating engine having a plurality of cylinders (cylinders) in which combustion is intermittently performed in each explosion (combustion) stroke, a periodical cycle is used in each explosion stroke. Combustion fluctuation amount detection means capable of detecting the combustion fluctuation amount that occurs in the engine is provided, whereby the combustion state of the engine can be determined.

In this prior art, the combustion fluctuation amount detecting means is: Engine speed variation 2. 2. Amount of change in torque between two cylinders selected from a plurality of cylinders during the explosion stroke. After obtaining three kinds of data of the in-cylinder pressure fluctuation amount of the engine and obtaining the sequential combustion fluctuation amount from them, the change amount of each combustion fluctuation amount between the two cylinders' explosive strokes is calculated. It was configured to calculate the standard deviation of and obtain a burn index.

[0005]

In the above-mentioned prior art, it should be noted that a predetermined timing signal must be generated when each combustion fluctuation or the like is obtained from the amount of change between the explosion strokes of two cylinders. Therefore, for example, when it is attempted to be processed by a microcomputer or the like, the internal hardware must be constructed exclusively, and therefore, there is a problem that other control processing is restricted. there were.

Further, in the above-mentioned prior art, no consideration is given to the fact that the operating state of the engine may be changed by an external command such as a command from the driver of the automobile. The change in the operating state due to the above is also grasped as the combustion fluctuation amount of the engine, and this is judged as the deterioration of the combustion state. Therefore, in the transient state, there is a problem that the calculation of the combustion index must be stopped.

Therefore, even if the calculation is stopped in this way, it is necessary to surely detect the transient state for that purpose. For this purpose, for example, a highly accurate throttle valve opening sensor is used. It needs to be installed accurately, and thus the system becomes large in scale and the cost increases.
Furthermore, the conditions for determining the combustion index are complicated, and there is a problem that it is extremely difficult to match the constants.

The present invention has been made by paying attention to the problems of the prior art as described above, and an object thereof is to provide a high-accuracy sensor or the like without requiring setting of special interrupt timing. Providing a combustion state detection device that can detect the combustion index accurately without being affected by the transient operation of the engine without newly installing it, and that can easily match the initial constants To do.

[0009]

Means for Solving the Problems The above-mentioned objects include means for detecting a rotational fluctuation of an internal combustion engine, means for storing a representative pattern of the detected rotational fluctuation, and an orthonormal pattern of the representative pattern of the rotational fluctuation. Means for storing, means for calculating a combustion index from the rotation fluctuation of the internal combustion engine and a representative pattern of these rotation fluctuations and the pattern of the orthonormal system are provided, and the combustion state of the internal combustion engine is detected by this combustion index. Will be achieved.

Here, the representative pattern of the rotational fluctuation is a numerical value of the magnitude of the rotational fluctuation, or a numerical value that imitates the rotational fluctuation is stored as time series data. The pattern is a pattern in which a phase difference of 90 ° is given to the representative pattern of rotation fluctuation.

[0011]

By using the representative pattern of rotation fluctuations and its orthonormal pattern and summing the product of these fluctuations and the rotation speed fluctuation of the output shaft, the phase difference at the time of detecting the combustion state can be absorbed. You can Therefore, the combustion state can be detected without considering the special timing for that.

Further, at this time, by setting a representative pattern of the rotational fluctuation for each rotational speed, the combustion state can be easily detected even during a transient time, and a means for separately detecting a transient state is provided. It can be unnecessary.

[0013]

The present invention will now be described in detail with reference to the illustrated embodiments. First, FIG. 2 is a block diagram of an engine control system to which an embodiment of the present invention is applied. In the figure, 100 represents an engine. This system detects and opens the thermal air flow meter 102 that measures the mass flow rate of the air drawn into the engine 100 and the opening of a throttle valve (throttle valve) that adjusts the flow rate of the drawn air. Of the throttle valve opening degree sensor 103 that outputs a degree signal, a control valve 104 that controls the amount of air passing through the bypass passage that is not detected by the thermal air flow meter 102, a fuel injection valve 105 that supplies a fuel amount required by the engine 100, an engine A spark plug 106 that ignites the mixture supplied to the cylinder, an oxygen concentration sensor 107 that is installed in the exhaust pipe and detects the oxygen concentration in the exhaust gas, and is installed around the output shaft of the engine 100. A ring gear 109 made of steel, in which 108, for example, 108 projections are arranged at equal intervals,
Of the magnetic detector 110, which is installed in the vicinity of the protrusion of the engine, detects the protrusion passing immediately before the engine by rotation, and generates a signal (crank angle signal POS), and signals from the various sensors described above. By engine 100
The operating state of the engine 1 is detected, and the engine 1
00 calculates the amount of fuel required and drives the fuel injection valve 105 and the like.

FIG. 3 is a block diagram of the internal circuit of the engine control unit 108, which is shown in FIG.
In addition to inputting signals from the various sensors shown in Fig. 1, a driver circuit 200 that functions to convert a small level signal into a large level signal for driving an actuator, and an analog-type input / output signal that can be digitally processed. An input / output circuit 201 for converting into a digital signal, a microcomputer for performing digital arithmetic processing or an arithmetic circuit 202 having an arithmetic function equivalent thereto, the arithmetic circuit 20.
ROM 20 serving as a non-volatile memory for storing constants, variables, programs, etc. used in the arithmetic processing
3. A RAM 204 which also functions as a volatile memory, and a backup circuit 205 which holds the contents of the volatile RAM 204.

In this embodiment, the digital arithmetic unit is used, but it goes without saying that an analog type arithmetic unit can also be used. And in this example,
As input signals, the oxygen concentration signal from the oxygen concentration sensor 107, the throttle valve opening signal from the throttle valve opening sensor 103, the crank angle signal from the magnetic detector 110, and the air flow rate signal from the thermal air flow meter 102. So that the ignition signal to be supplied to the spark plug 106, the idle speed control valve control signal to be supplied to the control valve 104, and the drive signal for the fuel injection valve 105 are output. Has become.

Next, FIG. 4 shows the engine control device 1 of FIG.
Reference numeral 08 indicates an embodiment in which an integrated circuit dedicated to signal processing is used, and the crank angle signal and the cylinder signal are input from the input / output driver circuit 300 to the integrated circuit dedicated to signal processing 301. A RAM 302 having a bidirectional bus is provided for data communication with an external control device. The arithmetic device 303, the memories 304 and 305, and the backup circuit 306 are the same as those in FIG.

In this specification, the rotation speed and the rotation speed are used in the same meaning.

Next, FIG. 5 shows the rotational fluctuation during the steady operation of the engine. In this embodiment, the case of a four-cylinder engine is shown. As is apparent from the enlarged view, four peaks are generated while the output shaft (crank shaft) of the engine makes two revolutions (720 ° CA). Note that CA is a crank angle.

FIG. 6 shows an internal processing block diagram of the magnetic detector 110. First, the waveform shaping circuit of the block 600 is used, in which the output p (PO
S) is normalized and then counted in the counter in block 601. Then, the counted data value is compared by the comparator 603 with the threshold value s of the predetermined value given from the block 602.

Thus, when the count data exceeds the threshold value s, the counter of the block 601 is reset, and at the same time, the value of the free-run timer of the block 604 is latched by the latch circuit of the block 605 and output to the bus of the control device. It Then, in block 606, the time measured by the free-run timer is converted into the rotation speed N.

FIG. 7 is a timing chart showing the signal states of the respective parts in the internal processing block diagram of FIG.
(a) represents the output signal of the magnetic detector 110, and
(b) shows the output signal q normalized by the waveform shaping circuit of the block 600, (c) shows the output signal r of the counter of the block 601, and (d) shows the output signal t of the free-run timer of the block 604. And (e) represents the rotation speed N calculated from the value t latched by the free-run timer.

Next, FIG. 8 shows the relationship between the fluctuation of the rotation speed N of the engine 100 and the air-fuel ratio A / F. The air-fuel ratio A / F is ideally known as 14.7. When the theoretical air-fuel ratio A / F ₁ , which is the mixing ratio, is reached,
As shown in, the rotation speed fluctuation state of almost triangular wave is shown,
As the air-fuel ratio shifts to the lean side where A / F ₁ > A / F ₂ > A / F ₃ , as shown in (b) and (c) of the figure, the waveform collapses from the triangular waveform and the waveform collapses. This has been confirmed by experiments. Note that this example is an example in the case of an embodiment using a four-cylinder engine, as described in FIG.

FIG. 9 shows a variation pattern of the engine rotation speed used in the embodiment of the present invention. FIG. 9 (a) shows a pattern representative of the actual engine rotation speed data. (b) is a triangular wave representative pattern simulating real data, (c) is a representative pattern similarly simulated in a rectangular wave shape, and (d) is a sine wave representative pattern. You may adopt the pattern of. Each representative pattern is shown in phase with the actual data shown in (a).

Here, the representative pattern of the rotational fluctuation is, as described above, a numerical value of the magnitude of the rotational fluctuation or a numerical value which imitates the rotational fluctuation is stored as time series data.

Next, the basic principle of combustion index detection according to the embodiment of the present invention will be described with reference to FIG. This Figure 1
At 0, 901 shows a pattern consisting of a representative waveform (triangular wave because of stoichiometric air-fuel ratio) data string representing a rotation fluctuation pattern of the engine at the stoichiometric air-fuel ratio, which is called a representative pattern. On the other hand, a pattern composed of a waveform data string having a phase difference of 90 ° with respect to this waveform is indicated by a broken line h, and this is called an orthonormal pattern. In this embodiment, as shown in the figure, these two types of waveform data are used, and these waveform data are stored and stored as table data in the engine control device 108 and superposed on the input rotation fluctuation data. (Multiplication) is performed to calculate the combustion index.

When the combustion index is calculated in this way, the integrated value between constant crank angles increases when the rotational fluctuation approaches the representative waveform. It can be easily determined that the fluctuation approaches the representative waveform. Therefore, according to this embodiment, the combustion state can be detected easily and accurately.

In this specification, these two types of waveform data strings, that is, the representative waveform data strings and the representative waveform data composed of the data strings having a phase difference of 90 ° are referred to as orthonormal system table data. Call. Then, the theoretical formula of this orthonormal system table data is expressed by the following formula. Here, S1 is the representative waveform data component of the representative waveform data string, and S2 is the phase difference 90 in the representative waveform data.
The data component of the representative waveform is represented by the representative waveform data string to which .degree. Is added, and in this embodiment, these 2
The norm S of the components of the seed is calculated and used as a fuel index.

[0028]

[Equation 1]

FIG. 1 shows an embodiment of a processing block for calculating a combustion index from rotation fluctuation data and representative waveform data according to the present invention. The engine control unit 108 shown in FIG.
In the figure, block 10 is a representative rotation fluctuation table group in which orthonormal system data of representative rotation fluctuation for each rotation speed is stored. The crank angle signal POS supplied from the magnetic detector 110 is input to
The engine 100 rotates and its output shaft (crankshaft) has a predetermined rotation angle, for example, in the case of FIG.
Each time 0/108 = 10/3 ° is reached, the orthonormal system data of each representative rotation fluctuation is read therefrom and supplied to the changeover switch 12.

A block 11 is a filter, to which the rotational speed N is input, which is filtered and the averaged engine rotational speed is output and input to the changeover switch 12.
Data from the representative rotation variation table group 10 is switched according to the engine speed at that time, and one of them is selected and input to the calculation block A.

The calculation block A is a part for executing the calculation processing shown in the equation 1, and in the block 13 in the calculation block A, the rotation fluctuation data contained in the rotation number N and the changeover switch 12 are first selected. The representative rotation variation data and the orthonormal data of the representative rotation variation consisting of the data having the phase difference of 90 ° are multiplied to obtain the representative waveform data component S1 shown in Expression 1 and the data having the phase difference of 90 ° between the representative waveform data. And component S2.

Next, the multiplication result of the block 13 is supplied to the integrator of the block 17 and integrated to form an integrated value S.

On the other hand, the blocks 14, 15 and 16 determine the integration section n in the equation 1 from the crank angle signal POS. Here, this integration section n is determined by the block 16
Based on the comparison data given by the engine 100
Is determined by the number of crank angle signals POS generated during the rotation of the crankshaft of 180 °, that is, 108/2 = 54.

In this way, the peak value of the integrated value S is taken out by the peak hold means represented by a switch in FIG. 1 and supplied to the block 18 for each integrated section n. This block 18 is composed of a map (three-dimensional table) in which the peak value of the integrated value S and the rotation speed N are used as search values (arguments), and the combustion index In determined from the peak value of the integrated value S and the rotation speed N is set. Perform output calculation.

FIG. 11 is a characteristic diagram in which the relationship between the combustion index In calculated by the embodiment of FIG. 1 and the air-fuel ratio A / F is obtained as an experimental value. As shown in the figure, the air-fuel ratio A / F and the combustion index In Is found to be in an inversely proportional relationship. Therefore, according to this embodiment, the combustion state of the engine can always be accurately detected and determined. At this time, since there is variation in the data, it goes without saying that it is desirable to average by a weighted average or the like when it is applied to an actual control device.

Next, FIG. 12 shows another embodiment of the present invention. In this embodiment, the combustion index is obtained from the engine rotation fluctuation and the representative waveform data, and the combustion misfire is judged by this.
It is designed to be displayed to the driver.

In the embodiment shown in FIG. 12, the basic structure is
As in the embodiment shown in FIG. 1, the representative rotation pattern table when the engine is in the idle state is included in the representative rotation fluctuation table group, and the supply switch 12 is controlled by the idle signal IDLE. Also,
The combustion index I is obtained by using the orthonormal systematic data of the representative rotation fluctuation read from the idle representative rotation pattern table.
If n is calculated and the result of the calculation indicates that a misfire has occurred,
An alarm display is given to a driver of an automobile or the like by a predetermined display means.

Next, FIG. 13 shows the relationship between the engine speed N and the air-fuel ratio A / F, and the combustion index In detected by the embodiment of FIG. 1. The air-fuel ratio A / F is lean. It can be seen that the engine rotation becomes unstable and the combustion index In becomes smaller as it shifts to the side. Therefore, an embodiment of the combustion control device for the engine according to the present invention, which is configured by using the combustion index In according to the embodiment of FIG. 1, will be described below.

FIG. 14 is a block diagram showing an embodiment of a combustion control device according to the present invention. In the figure, a block 400 is shown.
Calculates the basic fuel amount from the detected intake air amount and engine speed of the engine 100. At the same time, a block 401 searches for a fuel amount correction coefficient, and a block 402 corrects the basic fuel amount. Then, the corrected basic fuel amount is input to the block 409. On the other hand, in block 403, the lean burn coefficient for obtaining the target lean air-fuel ratio is searched, and the lean burn coefficient searched here is further read in block 406 from the lean burn learning coefficient read from block 405. After being corrected by, the data is input to the block 409.

Further, at block 407, air-fuel ratio feedback by the oxygen concentration sensor is executed. Then, the coefficient calculated here is learned as an air-fuel ratio correction coefficient in the map by using the engine speed of the internal combustion engine and the basic fuel amount calculated in block 400 as an argument (search data) in block 408. 409 air-fuel ratio correction is performed.

Therefore, in block 409, block 4
The basic fuel amount supplied from the block 402 is corrected by one of the lean combustion coefficient from 06 and the air-fuel ratio correction coefficient from the block 408, and is supplied to the fuel injection valve 105 to control the fuel supply amount to the engine 100. Will be executed. The coefficient used for correction in this block 409 can be switched according to the operating state of the engine.

Here, the block 404 is a portion for performing the same processing as that of the combustion state detecting device shown in FIG. 1, and when the engine 100 is in the lean combustion state and the rotation becomes unstable,
As shown in FIG. 13, the combustion index In becomes smaller. Then, the fact that it has reached the limit is detected by comparison with a preset threshold value. Then, according to the lean burn limit data from this block 404, the block 40
It is learned in the learning region by lean burn coefficient learning of No. 5, and is reflected in the lean burn learning coefficient of block 406.

Therefore, according to the embodiment of FIG. 14, when the combustion index In becomes smaller than a certain threshold value, the air-fuel ratio A / F is controlled accordingly, that is, the air-fuel mixture becomes richer. As a result, the operating condition of the engine can always be kept stable.

Next, FIG. 15 is a general flow chart showing the combustion control process in the embodiment of FIG.
When this process is started, first, the thermal air flow meter 102
From the crank angle sensor including the magnetic detector 110, and the oxygen concentration in the exhaust gas is read from the oxygen concentration sensor 109 (steps 1800, 1801, 1802).

Next, the basic fuel amount is calculated based on these parameters (step 1803). Then, in step 1804, it is determined whether or not it is in the stoichiometric air-fuel ratio region,
If it is in the stoichiometric air-fuel ratio region, air-fuel ratio feedback is started based on the output of the oxygen concentration sensor 109, and the first fuel amount is calculated (steps 1805 and 1806).

However, if it is outside the stoichiometric air-fuel ratio region, the target air-fuel ratio is searched to calculate the combustion index which is the lean combustion limit (steps 1807 and 1808), and then the lean combustion coefficient is searched, whereby the lean burn coefficient is leaned. The combustion correction coefficient is calculated, and the second
The fuel injection amount of (steps 1809 and 181)
0, 1811). Then, the calculated first and second injection amounts are set in the fuel injection control means in step 1812 and used for controlling the combustion injection valve 105.

Next, FIG. 16 is a general flowchart of the engine speed detection processing described in FIG.
It is determined whether or not it is immediately after the start (step 1900), and if it is immediately after the start, the counter, the free-run timer, etc. are initialized.
(Step 1901). After that, the counter is incremented (step 1902), then it is judged whether the counter is equal to or more than the threshold value (step 1903), and when it is equal to or more than the threshold value, the value of the free-run timer is latched (step 1904), and the value is set to the engine. CP of control device 108
It is sent to U (step 1905), and then the free-run timer and counter are reset (step 190).
6, 1907).

Next, FIG. 17 is a general flowchart of the combustion index calculation. First, in step 2000, it is judged whether or not the engine has just started, and if it has just started, each variable is initialized in step 2003. Turn into. After the initialization is completed, at the next calculation timing, the rotation fluctuation time obtained in the processing of FIG. 16 is fetched and converted into the rotation speed (step 2001).

In step 2002, this rotation speed is filtered, and in step 2004, the reference rotation fluctuation table is searched using this filtered rotation speed. Then, in step 2005, the data of the representative rotation fluctuation table and the fetched rotation fluctuation are multiplied and integrated. This is similarly performed for the phase difference 90 ° data. In this way, when the crank angle of a constant angle is integrated, the norm is calculated in step 2007, and the combustion index is retrieved and calculated in the following step 2008.
Note that the general flowchart is almost the same when calculating the combustion index and the combustion misfire, so it will be omitted here.

Therefore, according to the above embodiment, stable lean combustion control of the engine can be easily obtained. Further, since the combustion state can be detected even when the engine is in the idle state, misfire detection can be reliably performed even when the engine is idle.

By the way, in the above embodiment, the ring gear and the magnetic detector are used as means for detecting the engine speed. However, in an automobile engine, the ring gear and the magnetic detector are built in a distributor (distributor). There is a case where a rotation speed detector is used in which a disc with a slit attached to a shaft is used and the rotation speed is obtained by detecting the slit with an optical detector including a light source and a photodiode.

Therefore, it goes without saying that the present invention can also be implemented using such an optical rotation detector.

[0053]

According to the present invention, since both the representative pattern of the rotational fluctuation of the internal combustion engine and the orthonormal pattern thereof are used and summed with the rotational fluctuation, the calculation start timing Since it is not necessary to consider the phase adjustment and the like, the structure is simplified, and the risk of cost increase can be eliminated.

Further, since it can be installed for each number of revolutions as a representative pattern of rotational fluctuation, it is not necessary to use a highly accurate accelerator opening sensor or the like, and the combustion state can be reliably detected even in transient fluctuations. Moreover, the combustion state can be detected even during idling.

[Brief description of drawings]

FIG. 1 is a control block diagram of combustion state detection according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an example of an engine control system to which an embodiment of the present invention is applied.

FIG. 3 is a block diagram showing an example of an engine control device according to an embodiment of the present invention.

FIG. 4 is a block diagram showing another example of the engine control device in the embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an example of rotational fluctuation of the output shaft of the internal combustion engine.

FIG. 6 is a control block diagram showing an example of rotation fluctuation measurement processing in an embodiment of the present invention.

FIG. 7 is a timing chart for explaining the process of FIG.

FIG. 8 is a waveform diagram showing the relationship between the rotational fluctuation of the internal combustion engine and the air-fuel ratio.

FIG. 9 is an explanatory diagram of a representative pattern of rotation fluctuations of an internal combustion engine used in an embodiment of the present invention.

FIG. 10 is an explanatory diagram showing the basic concept of combustion state detection according to the present invention.

FIG. 11 is a characteristic diagram showing the relationship between the combustion index and the air-fuel ratio of the internal combustion engine according to the present invention.

FIG. 12 is a control block diagram of combustion state detection according to another embodiment of the present invention.

FIG. 13 is a characteristic diagram showing the relationship between the engine speed of the internal combustion engine, the air-fuel ratio, and the combustion index in one embodiment of the present invention.

FIG. 14 is a block diagram showing an embodiment of a fuel injection amount control device for an internal combustion engine according to the present invention.

FIG. 15 is a general flowchart for explaining the operation of the embodiment of the fuel injection amount control device for the internal combustion engine according to the present invention.

FIG. 16 is a general flowchart for explaining a rotation fluctuation fetching process according to an embodiment of the present invention.

FIG. 17 is a general flowchart for explaining a combustion index calculation process according to an embodiment of the present invention.

[Explanation of symbols]

 100 Internal Combustion Engine 102 Thermal Air Flowmeter 103 Throttle Valve Opening Sensor 105 Fuel Injection Valve 106 Spark Plug 107 Oxygen Concentration Sensor 108 Engine Control Device 109 Ring Gear 110 Magnetic Detector

Claims (12)

[Claims] 1. A means for detecting the rotational speed of an output shaft of an internal combustion engine, a means for detecting a rotational fluctuation from the rotational speed detected by this means, a means for storing a representative pattern of the detected rotational fluctuation, Means for storing the orthonormal system pattern of the representative pattern of the rotational fluctuations, and means for calculating a combustion index from the representative pattern of the rotational fluctuations, the orthonormal pattern and the rotational fluctuation of the internal combustion engine are provided. A combustion state detection device for an internal combustion engine, which is configured to detect a combustion state of the internal combustion engine using an index. 2. The magnetic device according to claim 1, wherein the means for detecting the rotational speed of the output shaft of the internal combustion engine is arranged at equal intervals along the same circumferential surface centered on the output shaft of the internal combustion engine. A combustion state detecting device for an internal combustion engine, comprising: a gear having a body protrusion row; and a magnetic detector installed at a constant distance from the gear protrusion row. 3. The invention according to claim 1, wherein the means for detecting the rotational speed of the output shaft of the internal combustion engine is provided with a slit provided on the shaft driven from the output shaft of the internal combustion engine via the rotation transmission means. A combustion state detecting device for an internal combustion engine, comprising a disc and an optical detector for detecting a slit of the disc. 4. The invention according to claim 1, wherein the means for detecting fluctuations in the number of revolutions of the internal combustion engine detects fluctuations in the number of revolutions as a time-series variable of the time required to rotate the output shaft at a constant rotation angle. A combustion state detection device for an internal combustion engine, comprising: 5. The invention according to claim 1, wherein the means for detecting fluctuations in the rotational speed of the internal combustion engine detects the fluctuations in rotational speed as a time-series variable of the rotational angle of the output shaft of the internal combustion engine within a fixed time. A combustion state detection device for an internal combustion engine, which is configured. 6. The combustion state detecting device for an internal combustion engine according to claim 1, wherein the representative pattern of the rotation fluctuation of the output shaft is a pattern storing actual data of the internal combustion engine. 7. The combustion state detecting device for an internal combustion engine according to claim 1, wherein the representative pattern of the rotation fluctuation of the output shaft is a triangular wave pattern simulating actual data of the internal combustion engine. 8. The combustion state detecting device for an internal combustion engine according to claim 1, wherein the representative pattern of the rotation fluctuation of the output shaft is a rectangular wave pattern imitating actual data of the internal combustion engine. 9. The combustion state detecting device for an internal combustion engine according to claim 1, wherein the representative pattern of the rotation fluctuation of the output shaft is a sine wave pattern that imitates actual data of the internal combustion engine. 10. The invention according to claim 1, wherein the means for calculating the combustion index is a product sum of rotation fluctuation of the output shaft between constant rotation angles of the output shaft and a representative pattern of the rotation fluctuation of the output shaft. And a combustion state detection device for an internal combustion engine, which is configured to obtain a combustion index from a rotation variation of the output shaft and a sum of squares of products of the orthonormal system patterns. 11. The combustion state detecting device for an internal combustion engine according to any one of claims 1 to 10, further comprising means for displaying the combustion index so that a combustion state is displayed in real time. . 12. A combustion state detecting device for an internal combustion engine according to claim 1, wherein the internal combustion engine control device comprises a fuel amount calculating means for calculating a fuel supply amount from an intake air amount and a rotational speed of the internal combustion engine. A combustion control device for an internal combustion engine, characterized in that any one of the above is used, and the fuel supply amount is corrected by a combustion index given thereby.