JP3336811B2 - Apparatus for determining combustion state of internal combustion engine and apparatus for controlling combustion state of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine suitable for a lean-burn internal combustion engine that performs a lean-burn operation at a leaner air-fuel ratio than a stoichiometric air-fuel ratio under required operating conditions. The present invention relates to a combustion state determination device and a combustion state control device for an internal combustion engine that controls a combustion state of an internal combustion engine using a result of determination by the determination device.

[0002]

2. Description of the Related Art In recent years, a lean-burn internal combustion engine (so-called lean burn engine) has been provided which performs a lean-burn operation at a leaner air-fuel ratio (lean) than a stoichiometric air-fuel ratio (stoichio) under required operating conditions. I have. In such a lean-burn engine, during lean-burn operation (lean-burn operation), the air-fuel ratio is set as large as possible (that is, the air-fuel mixture is made as lean as possible) in order to reduce NOx emissions. The value of the fuel ratio is set near a limit (lean limit) at which the mixture can perform stable combustion.

[0003] By performing such lean burn operation, NOx emission can be suppressed and fuel efficiency can be greatly improved.

[0004]

By the way, in order to perform lean burn operation, a control device controls a combustion state. In this control, it is necessary to estimate an engine torque from an angular acceleration of a crankshaft. Published in papers. However, these estimates are
It is performed every moment using the changing instantaneous value,
Considering the probability and statistical properties of the engine torque Pi, it has not been considered to perform stable and reliable control at predetermined intervals.

As shown in FIG. 25 , combustion fluctuations in the engine vary among the cylinders, and the variations occur due to variations in the air-fuel ratio due to deviations in the injector, intake pipe shape, valve timing, and the like. For this reason, in the lean burn operation, the combustion state is controlled so as to correspond to the air-fuel ratio of the cylinder having the largest combustion fluctuation.

However, the above-described means has a problem that it is impossible to operate at the limit air-fuel ratio in a cylinder having a relatively small combustion fluctuation. Therefore, it is conceivable to perform control for each cylinder, and as the variation data on which control is based, there are cases where an absolute value of angular acceleration that changes depending on the combustion state is used and a case where an angular acceleration change rate is used. Can be

[0007] Here, the fluctuation state of the torque corresponding to the combustion state is as shown in FIG. 24 , and FIG. 24 shows the state of generation of torque with time, with the vertical axis representing torque and the horizontal axis representing time. ing. That is, when the absolute value of the angular acceleration is used, the combustion state is determined based on the sum of the inter-cylinder torque difference (average value) and the torque fluctuation amount.

When the rate of change of angular acceleration is used,
Figure 24, as indicated by the interval [Delta] T, will determine the combustion state by the amount of fluctuation from the cylinders between the torque difference (average value). Considering the control state by these means, when the control is performed using the latter torque fluctuation amount, it is possible to determine the intermittent misfire and to cope with the deterioration of the driving feeling caused by the intermittent misfire. However, since torque fluctuation does not occur in the continuous misfire state, the state may not be detected.

Therefore, when the continuous misfire is not detected, the air-fuel ratio should be enriched and the operation should be shifted to the normal operation. Is not performed, the output of the cylinder is reduced, and an unbalanced operation relying on the outputs of other cylinders is performed. On the other hand, when the absolute value of the angular acceleration is used, continuous misfires can be detected and dealt with, but for intermittent misfires, the torque variation Is offset by the positive / negative value of the inter-cylinder torque and cannot be obtained, the accuracy of the determination of intermittent misfire is poor, and there is a problem that it is not possible to sufficiently cope with the feeling deterioration.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and in consideration of the probability and statistical properties of the combustion fluctuation during lean burn operation, reliable combustion state determination and, hence, combustion state control, especially continuous misfire and An object of the present invention is to provide a combustion state determination device for an engine and a combustion state control device for an internal combustion engine, which are capable of performing reliable combustion state determination for each cylinder that can cope with both intermittent misfires and thus performing combustion state control. I do.

[0011]

According to a first aspect of the present invention, there is provided an apparatus for determining a combustion state of an engine according to the first aspect of the present invention, wherein the first operating state parameter fluctuates due to a torque difference between cylinders of an internal combustion engine having a plurality of cylinders. Operating state detecting means for detecting the first operating state parameter, and integrating the first operating state parameter detected by the first operating state detecting means for each cylinder to calculate a first combustion state determination value for each cylinder. 1 determination value calculating means, second operating state detecting means for detecting a second operating state parameter that changes due to torque fluctuation for each cylinder of the internal combustion engine, and the second operating state detecting means a second judgment value calculating means for calculating a second combustion state determination value for each cylinder by multiplying for each cylinder of the second operating condition parameter, the accumulation by the first determination value calculating means
And the second combustion state determination value calculated by the integration by the second determination value calculation means.
And combustion state determining means for determining the combustion state of the internal combustion engine based on both of the above.

According to a first aspect of the present invention, the first operating state detecting means detects a rotational angular acceleration of the internal combustion engine as the first operating state parameter. (Claim 2). Further, in the combustion state determination device for an internal combustion engine according to claim 2, means may be provided for correcting the rotational angular acceleration of the internal combustion engine detected by the first operating state detection means with the load information of the internal combustion engine. ( Aspect 1 ).

Further, in the combustion state determining apparatus for an internal combustion engine according to claim 1, the second operating state detecting means detects a change in the rotational angular acceleration of the internal combustion engine as the second operating state parameter. (Claim 3 ). Further, in the combustion state determining apparatus for an internal combustion engine according to claim 3 , the second operating state detecting means calculates a difference between an actually measured value of the rotational angular acceleration of the internal combustion engine and a smoothed value of the rotational angular acceleration detected up to that time. It may be configured to detect the rotation angular acceleration change amount based on the deviation ( aspect 2 ).

Further, in the second aspect, there may be provided a means for correcting the measured value of the rotational angular acceleration of the internal combustion engine with the load information of the internal combustion engine (third aspect). Further, in the combustion state determination device for an internal combustion engine according to claim 1, wherein the second judgment value calculating means may be integrated only those with a negative value of the rotation angular acceleration change amount (according Item 4 ).

Further, in the combustion state determining apparatus for an internal combustion engine according to claim 1, the combustion state determining means includes a first combustion state determination value and a first predetermined value calculated by the first determination value calculation means by integration. May be configured to determine that a continuous misfire has occurred in the cylinder (claim 5 ). Further, in the combustion state determination device for an internal combustion engine according to claim 5 , the combustion state determination means may be configured to set the first predetermined value based on an operation state of the internal combustion engine (aspect 4 ). .

Further, in the fourth aspect, the combustion state determining means may be configured to set the first predetermined value based on a rotation speed and a load of the internal combustion engine (an aspect).
5 ). Further, in the combustion state determination device for an internal combustion engine according to claim 1, the combustion state determination means compares a second combustion state determination value calculated by integration by the second determination value calculation means with a second predetermined value. Then, it may be configured to determine that intermittent misfire has occurred in the cylinder (claim 6 ).

Further, in the combustion state determining apparatus for an internal combustion engine according to claim 6 , the combustion state determining means may be configured to set the second predetermined value based on an operating state of the internal combustion engine ( Aspect 6 ). In the sixth aspect, the combustion state determination means may be configured to set the second predetermined value based on a rotation speed and a load of the internal combustion engine (aspect 7 ).

Further, in the combustion state determining apparatus for an internal combustion engine according to claim 1, the combustion state determining means includes:
The first combustion state determination value calculated by the first determination value calculation means by integration is compared with a first predetermined value to determine that a continuous misfire has occurred in the cylinder, and to perform the second determination. The second combustion state determination value calculated by the integration by the value calculation means may be compared with a second predetermined value to determine that intermittent misfire has occurred in the cylinder. 7 ).

Further, in the combustion state determining apparatus for an internal combustion engine according to claim 7 , the combustion state determining means sets the first predetermined value and the second predetermined value based on a rotation speed and a load of the internal combustion engine. May be configured (aspects
8 ). Further, a combustion state control device for an internal combustion engine according to the present invention (Claim 8 ) includes a first operation state detection means for detecting a first operation state parameter that fluctuates due to a torque difference between cylinders of an internal combustion engine having a plurality of cylinders. A first determination value calculation unit that integrates the first operation state parameter detected by the first operation state detection unit for each cylinder to calculate a first combustion state determination value for each cylinder; A second operating state detecting means for detecting a second operating state parameter that changes due to a torque variation for each cylinder of the engine; and a second operating state parameter detected by the second operating state detecting means for each cylinder. A second combustion state determination value for each cylinder to calculate a second combustion state determination value for each cylinder; a first combustion state determination value calculated by integration by the first determination value calculation means; Performance Means for determining the combustion state of the internal combustion engine based on both the second combustion state determination value calculated by the integration by the calculation means, and combustion based on the determination result of the combustion state determination means. It is characterized by having combustion state control means for controlling the state.

In the combustion state control device for an internal combustion engine according to claim 8 , the first operating state detecting means is configured to detect a rotational angular acceleration of the internal combustion engine as the first operating state parameter. (Claims
9 ). Further, in the combustion state control device for an internal combustion engine according to the ninth aspect, means may be provided for correcting the rotational angular acceleration of the internal combustion engine detected by the first operating state detection means with the load information of the internal combustion engine. (Aspect 9 ).

Further, in the combustion state control device for an internal combustion engine according to claim 8 , the second operating state detecting means detects a change in the rotational angular acceleration of the internal combustion engine as the second operating state parameter. In addition, the rotational angular acceleration change amount may be obtained based on a deviation between an actual measured value of the rotational angular acceleration of the internal combustion engine and a smoothed value of the rotational angular acceleration detected up to then ( Claim 10 ).

Further, in the combustion state control device for an internal combustion engine according to claim 10, the measured value of the rotational angular acceleration of the internal combustion engine may be provided with means for correcting the load information of the engine (mode 10). An internal combustion engine according to claim 10.
The second determination value calculating means
Has a negative value among the changes in the rotational angular acceleration described above.
Only the sum may be added (claim 11).

[0023]

[0024]

[0025]

In the above-described apparatus for determining a combustion state of an engine according to the present invention (claim 1), the first operating state detecting means varies the first operating state caused by the inter-cylinder torque difference of the internal combustion engine having a plurality of cylinders. The parameters are detected, the first operating state parameters detected by the first operating state detecting means are integrated for each cylinder by the first determination value calculating means, and a first combustion state determination value for each cylinder is calculated. . Further, a second operating state parameter that changes due to a torque variation for each cylinder of the internal combustion engine is detected by the second operating state detecting means, and the second operating state parameter detected by the second operating state detecting means is detected by the second operating state detecting means.
The operating state parameter is integrated for each cylinder by the second determination value calculation means, and a second combustion state determination value for each cylinder is calculated. And integrated by the first determination value calculating means.
The combustion state of the internal combustion engine is determined by the combustion state determination means based on both the first combustion state determination value calculated by the above and the second combustion state determination value calculated by integration by the second determination value calculation means. .

In the combustion state determining apparatus for an internal combustion engine according to the second aspect, the operation of the apparatus according to the first aspect is characterized in that the first operating state detecting means determines the rotational angular acceleration of the internal combustion engine as a first operating state parameter. Is detected. Also, aspects
In the first aspect , the operation of the device according to the second aspect is described in the first aspect.
The rotational angular acceleration of the internal combustion engine detected by the operating state detecting means is corrected based on the load information of the internal combustion engine.

Further, in the combustion state determining apparatus for an internal combustion engine according to the third aspect , the operation of the apparatus according to the first aspect is as follows.
The change amount of the rotational angular acceleration of the internal combustion engine is detected as the second operation state parameter by the second operation state detection means. According to the second aspect , in the operation of the device according to the third aspect , the deviation between the actually measured value of the rotational angular acceleration of the internal combustion engine and the smoothed value of the rotational angular acceleration detected so far by the second operating state detecting means. Is obtained as the rotation angular acceleration change amount.

According to a third aspect, in the operation of the device according to the second aspect, the measured value of the rotational angular acceleration of the internal combustion engine is corrected with the load information of the internal combustion engine. According to a fourth aspect , in the operation of the device according to the third aspect , the second determination value calculating means integrates only the rotation angular acceleration change amount having a negative value.

Further, in the combustion state determining apparatus for an internal combustion engine according to the fifth aspect , the operation of the apparatus according to the first aspect is as follows.
The first determination value calculated by the integration by the first determination value calculation means
The combustion state determination unit compares the combustion state determination value with the first predetermined value and determines that continuous misfire has occurred in the cylinder. In a fourth aspect, for the operation of the device according to the fifth aspect, the first predetermined value based on the operating state of the internal combustion engine is set by the combustion state determining means.

In a fifth aspect, the operation of the device according to the fourth aspect is based on the first operation based on the rotational speed and the load of the internal combustion engine.
The predetermined value is set by the combustion state determination means. Furthermore, in the combustion state determination device for an internal combustion engine according to claim 6 ,
In the operation of the device according to claim 1, the second combustion state determination value calculated by the integration by the second determination value calculation means is compared with a second predetermined value, and an intermittent misfire occurs in the cylinder. Is determined by the combustion state determining means.

In the sixth aspect, the second predetermined value based on the operating state of the internal combustion engine is set by the combustion state determining means in the operation of the device according to the sixth aspect. Further, in the mode 7 , in the operation of the device according to the mode 6 , the second predetermined value based on the rotation speed and the load of the internal combustion engine is set by the combustion state determining means.

Further, in the combustion state determining apparatus for an internal combustion engine according to the seventh aspect , the operation of the apparatus according to the first aspect is as follows.
The first determination value calculated by the integration by the first determination value calculation means
By comparing the combustion state determination value with the first predetermined value, it is determined that continuous misfire has occurred in the cylinder, and the second combustion state calculated by the second determination value calculation means by integration. The combustion state determination means compares the determination value with the second predetermined value and determines that intermittent misfire has occurred in the cylinder.

In the eighth aspect, in the operation of the device according to the seventh aspect, the setting of the first predetermined value and the second predetermined value based on the rotation speed and the load of the internal combustion engine is performed by the combustion state determination means. . In the combustion state control device for an internal combustion engine according to claim 8 , the first operating state detecting means detects a first operating state parameter that fluctuates due to a torque difference between cylinders of the internal combustion engine having a plurality of cylinders, First
The first operating state parameter detected by the operating state detecting means is integrated by the first determination value calculating means for each cylinder, and a first combustion state determination value for each cylinder is calculated.
Further, a second operating state parameter that changes due to a torque variation for each cylinder of the internal combustion engine is detected by the second operating state detecting means, and the second operating state parameter detected by the second operating state detecting means is the second operating state parameter. The second combustion state determination value for each cylinder is calculated by integrating the values for each cylinder by the two determination value calculation means. The first combustion state determination value calculated by the integration by the first determination value calculation means and the second combustion state determination value
The combustion state of the internal combustion engine is determined by the combustion state determination means based on both the second combustion state determination value calculated by the integration by the determination value calculation means, and the combustion control based on the determination result is performed by the combustion state control. This is done by means.

In the combustion state control device for an internal combustion engine according to the ninth aspect of the present invention, the operation of the device according to the eighth aspect is characterized in that the first operating state detecting means detects the rotation angular acceleration of the internal combustion engine as a first operating state parameter. Is detected. Also, aspects
In the ninth aspect , the operation of the device according to the ninth aspect is described in the first aspect.
The rotational angular acceleration of the internal combustion engine detected by the operating state detecting means is corrected based on the load information of the internal combustion engine.

Further, in the combustion state control device for an internal combustion engine according to the tenth aspect , the operation of the device according to the eighth aspect is characterized in that the second operating state detecting means detects the change in the rotational angular acceleration of the internal combustion engine as a second operating state parameter. The amount is detected, and the deviation between the actually measured value of the rotational angular acceleration of the internal combustion engine and the smoothed value of the rotational angular acceleration detected so far is obtained as the rotational angular acceleration change amount.

According to a tenth aspect, in the operation of the device according to the tenth aspect, the measured value of the rotational angular acceleration of the internal combustion engine is corrected with the load information of the internal combustion engine. In claim 11, the operation of the device according to claim 10 is performed.
The rotation angle acceleration is calculated by the second determination value calculation means.
Only the change amount having a negative value is integrated.

[0037]

[0038]

[0039]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an engine combustion state control apparatus using an engine combustion state determination apparatus according to an embodiment of the present invention. FIG. 3 is a hardware block diagram showing a control system of the engine system having the device, FIGS. 4 to 8 are flow charts for explaining the operation of the device , FIGS.
10 is a waveform diagram for explaining the operation of the present apparatus, FIGS. 11 and 12 are correction characteristic maps for explaining the operation of the present apparatus, respectively, and FIGS. 13 and 14 are each for explaining the operation of the present apparatus. schematic depicts graphs, schematic perspective view 15 showing the rotation variation detection unit in the apparatus for, FIG. 16
23 to 23 are schematic graphs for explaining the operation of the present apparatus, FIG. 24 is a graph showing a torque fluctuation characteristic in a lean burn engine , and FIG. 25 is a graph showing a combustion fluctuation characteristic in a lean burn engine.

Now, an engine for a vehicle equipped with the present device has a stoichiometric air-fuel ratio (stoichio) under required operating conditions.
Although it is configured as a lean burn engine that performs a lean burn operation (lean burn operation) at a leaner air-fuel ratio (lean), this engine system is as shown in FIG. That is, in FIG. 2, an engine (internal combustion engine) 1 has an intake passage 3 and an exhaust passage 4 that communicate with a combustion chamber 2 of the engine, and communication between the intake passage 3 and the combustion chamber 2 is controlled by an intake valve 5. In addition, the exhaust passage 4 and the combustion chamber 2 are controlled to communicate with each other by an exhaust valve 6.

The intake passage 3 is provided with an air cleaner 7, a throttle valve 8, and an electromagnetic fuel injection valve (injector) 9 in this order from the upstream side, and the exhaust passage 4 is provided in the exhaust passage 4 in order from the upstream side. , A three-way catalyst 10 and a muffler (muffler) not shown. In addition, the injector 9 is provided for each cylinder of the engine 1. Further, a surge tank 3a is provided in the intake passage 3.

The three-way catalyst 10 purifies CO, HC and NOx in the stoichiometric operation state, and is a known one. Further, the throttle valve 8 is connected to an accelerator pedal (not shown) via a wire cable, and the opening is adjusted according to the amount of depression of the accelerator pedal.

The intake passage 3 is provided with a first bypass passage 11A that bypasses the throttle valve 8, and the first bypass passage 11A has a stepper motor valve (hereinafter, referred to as an STM valve) that functions as an ISC valve. 12 are interposed. The first bypass passage 11A includes:
A wax type fast idle air valve 13 whose opening is adjusted according to the temperature of the engine cooling water is also provided, and is provided alongside the STM valve 12.

Here, the STM valve 12 is provided with a valve body 12a which can abut a valve seat formed in the first bypass passage 11A.
And a stepper motor (I) for adjusting the valve body position.
SC actuator) 12b, and a spring 12c that urges the valve body against the valve seat (in a direction that closes the first bypass passage 11A). The position of the valve body 12a with respect to the valve seat is adjusted stepwise (adjustment by the number of steps) by the stepper motor 12b, so that the opening degree of the valve seat 12 and the valve body 12a, that is, the STM valve 12
The degree of opening is adjusted.

Accordingly, the electronic control unit (ECU) 2 as a controller described later determines the opening degree of the STM valve 12.
5, the intake air can be supplied to the engine 1 through the first bypass passage 11A irrespective of the operation of the accelerator pedal by the driver, and the throttle bypass intake air amount is adjusted by changing the opening degree. You can do it.

As an ISC actuator,
Instead of the stepper motor 12b, a DC motor may be used. Further, a second bypass passage 11B that bypasses the throttle valve 8 is provided in the intake passage 3, and an air bypass valve 14 is interposed in the second bypass passage 11B.

Here, the air bypass valve 14 is connected to the second
It is composed of a valve element 14a that can abut on a valve seat formed in the bypass passage 11B and a diaphragm actuator 14b for adjusting the position of the valve element. The diaphragm chamber of the diaphragm actuator 14b has: A pilot passage 141 communicating with the intake passage downstream of the throttle valve is provided.
An electromagnetic valve 142 for controlling an air bypass valve is interposed in 41.

Therefore, by controlling the opening of the solenoid valve 142 for controlling the air bypass valve by the ECU 25 described later, in this case as well, regardless of the operation of the accelerator pedal by the driver, the opening through the second bypass passage 11B is performed. The intake air can be supplied to the engine 1 and the throttle bypass intake air amount can be adjusted by changing the opening degree. The air bypass valve control solenoid valve 142 is opened during the lean burn operation.
Other than that, the basic operation is to close.

An exhaust gas recirculation passage (EGR passage) for returning exhaust gas to the intake system is provided between the exhaust passage 4 and the intake passage 3.
The EGR passage 80 is provided with an EG
An R valve 81 is interposed. Here, the EGR valve 81
Is composed of a valve body 81a that can contact a valve seat formed in the EGR passage 80, and a diaphragm actuator 81b for adjusting the position of the valve body. The diaphragm actuator 81b is provided in the diaphragm chamber of the diaphragm actuator 81b. Is provided with a pilot passage 82 communicating with the intake passage downstream of the throttle valve.
In addition, an ERG valve control electromagnetic valve 83 is interposed.

Accordingly, by controlling the opening degree of the EGR valve control electromagnetic valve 83 by the ECU 25 described later,
Exhaust gas can be returned to the intake system through the GR passage 80. In FIG. 2, reference numeral 15 denotes a fuel pressure regulator, which operates by receiving a negative pressure in the intake passage 3 and regulates the amount of fuel returning from a fuel pump (not shown) to the fuel tank. Thus, the pressure of the fuel injected from the injector 9 is adjusted.

In order to control the engine system, various sensors are provided. First, as shown in FIG. 2, the intake air passing through the air cleaner 7 is
An air flow sensor (intake amount sensor) 17 that detects the amount of intake air from Karman vortex information and an intake temperature sensor 1 that detects the temperature of intake air of the engine 1
8. An atmospheric pressure sensor 19 is provided.

The throttle valve 8 in the intake passage 3
Is provided with an idle switch 21 in addition to a potentiometer-type throttle position sensor 20 for detecting the opening of the throttle valve 8.

Further, on the exhaust passage 4 side, a linear oxygen concentration sensor (hereinafter simply referred to as “linear O 2 concentration sensor”) that linearly detects the oxygen concentration (O ₂ concentration) in the exhaust gas on the air-fuel ratio lean side.
₂ ), a water temperature sensor 23 for detecting a temperature of cooling water for the engine 1 and a crank angle sensor 24 for detecting a crank angle shown in FIG. 3 (this crank angle sensor). 24 also functions as a rotation speed sensor for detecting the engine rotation speed Ne), a vehicle speed sensor 30, and the like.

The detection signals from these sensors and switches are input to the ECU 25 as shown in FIG. Here, the hardware configuration of the ECU 25 is as shown in FIG.
Is configured as a computer having a CPU (arithmetic unit) 26 as a main part thereof. The CPU 26 includes an intake air temperature sensor 18, an atmospheric pressure sensor 19, a throttle position sensor 20, a linear O ₂ sensor 22, a water temperature sensor 23. Are detected by the input interface 28
And an analog / digital converter 29.

The CPU 26 includes an air flow sensor 17, an idle switch 21, a crank angle sensor 24,
A detection signal from the vehicle speed sensor 30 or the like is directly input via the input interface 35. Further, the CPU 26 stores, via a bus line, a ROM that stores various data in addition to program data and fixed value data.
(Storage means) 36 or RAM which is updated and sequentially rewritten
Data is exchanged with the T.37.

As a result of the calculation by the CPU 26, EC
From U25, signals for controlling the operating state of the engine 1, such as a fuel injection control signal, an ignition timing control signal,
Various control signals such as an ISC control signal, a bypass air control signal, and an EGR control signal are output. Here, the fuel injection control (air-fuel ratio control) signal is
Through an injection driver 39 to an injector solenoid 9a for driving the injector 9 (more precisely, a transistor for the injector solenoid 9a).
6 through an ignition driver 40 to a power transistor 41, and a spark is sequentially generated in each ignition plug 16 by a distributor 43 from the power transistor 41 via an ignition coil 42.

The ISC control signal is output from the CPU 26 to the stepper motor 12b via the ISC driver 44, and the bypass air control signal is output from the CPU 26 via the bypass air driver 45 to the electromagnetic valve for controlling the air bypass valve. 142 is output to a solenoid 142a. Further, the EGR control signal is transmitted to the CPU 2
6 to the solenoid 83a of the ERG valve control electromagnetic valve 83 via the EGR driver 46.

Now, paying attention to the fuel injection control (air-fuel ratio control), for this fuel injection control (injector drive time control), the ECU 25, as shown in FIG. Acceleration detection means 10
7, smoothing means 108, threshold updating means 110, first operating state detecting means 202, second operating state detecting means 203, first judgment value calculating means 204, second judgment value calculating means 205,
The function of the combustion state control means 211, the combustion state determination means 212, and the load correction means 213 is provided.

Here, the combustion fluctuation adjusting element 106 adjusts the fuel injection pulse width Tinj to a desired state by a control signal from the combustion state control means 211, and performs a lean burn operation of an air-fuel ratio to be realized. , Injector 9
Function as the combustion fluctuation adjusting element 106. The fuel injection pulse width Tinj in the combustion state control means 211
Is represented by the following equation.

Tinj (j) = TB · KAC1 (j) ·
KAC2 (j) · K · KAFL + Td In this equation, TB is the basic drive time of the injector 9, the information on the intake air amount A from the air flow sensor 17 and the engine speed N from the crank angle sensor (engine speed sensor) 24. Based on this information, information on the intake air amount A / N per one revolution of the engine is obtained, and the basic drive time TB is determined based on this information.

KAFL is a leaning correction coefficient, which is determined according to the operating state of the engine from the characteristics stored in the map, so that the air-fuel ratio can be made lean or stoichiometric according to the operating state. ing. KAC1 (j) and KAC2 (j) are correction coefficients for performing the combustion state control corresponding to the combustion fluctuation in accordance with the determination result of the combustion state determination unit 212, as described later.

Further, a correction coefficient K is set according to the engine cooling water temperature, the intake air temperature, the atmospheric pressure, etc., and the driving time is corrected according to the battery voltage by the dead time (ineffective time) Td. I have. Further, the lean burn operation is configured to be performed when the predetermined condition is satisfied and the lean operation condition determination means determines the condition.

Thus, the ECU 25 has the function of air-fuel ratio control means for controlling the air-fuel ratio so that the air-fuel ratio becomes leaner than the stoichiometric air-fuel ratio under required operating conditions. By the way, the combustion state control device of the present embodiment includes an angular acceleration detecting means 107 for detecting an angular acceleration of a rotating shaft (crankshaft) driven by the engine. The angular acceleration detecting means 107 is configured as follows. Have been.

That is, as shown in FIG. 15 , the angular acceleration detecting means 107 includes a crank angle sensor 24, a cylinder discriminating sensor 230, and an ECU 25 as a controller as main elements.
A rotating member 221 that rotates integrally with the crankshaft 201 of the engine is provided. The first, second and third vanes 221 projecting in the radial direction are provided on the periphery of the rotating member 221.
A, 221B, and 221C are formed, and a detection unit 222 provided so as to face the vanes 221A, 221B, and 221C from both sides passes the vanes 221A, 221B, and 221C as the rotating member 221 rotates. the optically or electromagnetically detects, as shown in FIGS. 9 and 10, is configured as a pulse output as a crank angle signal.

Then, the vanes 221A, 221B, 22
1C each have a circumferential length corresponding to a crankshaft rotation angle of a fixed angle, and are arranged at predetermined intervals in the circumferential direction. That is, the opposing edges of the adjacent vanes are disposed at an interval of 120 degrees from each other, the rising portions of the vanes 221A, 221B, and 221C are formed so as to correspond to 75 ° BTDC of the crank angle, and the trailing edge is formed. It is formed so as to correspond to a crank angle of 5 ° BTDC.

The cylinder discrimination sensor 230 is fixed to a camshaft (not shown),
During one revolution of the camshaft and one revolution of the camshaft, a pulse output is generated each time the camshaft takes a specific rotational position corresponding to one cylinder. The device of this embodiment mounted on a six-cylinder engine in which the ignition operation is performed in the order of the cylinder number is, for example, the third vane 2
The edge (front end 221C ′ or rear end) of 21C is the detection unit 2
22, the first cylinder shaft rotation angle region corresponding to one of the first cylinder and the fourth cylinder (preferably, mainly the expansion stroke in the one cylinder) of the first cylinder group When the crankshaft enters and the edge of the first vane 221A passes the detection unit 222,
The crankshaft is separated from the first rotation angle range.

Therefore, when the edge of the third vane 221C passes through the detection unit 222, the pulse as the crank angle signal is turned on, and the first vane 221A is turned on.
The pulse as the crank angle signal becomes OFF state “0” when the edge of the sensor passes through the detection unit 222, and the crank angle signal rises at 5 ° BTDC approaching the combustion stroke, and the crank angle signal rises at the front of the combustion stroke. The pulse signal (see FIGS. 9 and 10 ) is turned off at 75 ° BTDC and turned on at 5 ° BTDC at the rear of the combustion stroke.

Similarly, when passing through the edge of the first vane 221A, it enters the second crankshaft rotation angle region corresponding to one of the second and fifth cylinders constituting the second cylinder group. When passing through the edge of the second vane 221B, the second vane 221B is separated from the area. Thereby, the pulse of the cylinders in the second cylinder group which rises at 5 ° BTDC approaching the combustion stroke, turns off at 75 ° BTDC at the front of the combustion stroke, and turns on at 5 ° BTDC at the rear of the combustion stroke. It is configured to output a signal.

Further, when passing through the edge of the second vane 221B, the second vane 221B enters the third crankshaft rotation angle region corresponding to one of the third and sixth cylinders constituting the third cylinder group. When passing through the edge of the three vanes 221C, separation from the same region is performed. Thereby, the pulse of the cylinders in the third cylinder group which rises at 5 ° BTDC approaching the combustion stroke, turns off at 75 ° BTDC at the front of the combustion stroke, and turns on at 5 ° BTDC at the rear of the combustion stroke. It is configured to output a signal.

The identification of the first cylinder and the fourth cylinder, the identification of the second cylinder and the fifth cylinder, and the identification of the third cylinder and the sixth cylinder are performed based on the output of the cylinder identification sensor 230. It is configured as follows. With such a configuration,
The detection of the angular acceleration is performed as follows. That is, during the operation of the engine, the ECU 25 sequentially receives the pulse output from the crank angle sensor 24 and the detection signal of the cylinder discrimination sensor 230, and repeats the calculation periodically.

The ECU 25 is provided with a crank angle sensor 2
Then, it is determined which of the pulse outputs from the cylinders 4 is sequentially input after the pulse output from the cylinder determination sensor 230 is input. Thereby, the input pulse output from the crank angle sensor 24 is identified as to which cylinder it corresponds to, and preferably,
The cylinder that is currently mainly performing the expansion stroke (output stroke: BTDC 75 °) is identified as the identification cylinder.

Then, in response to the pulse input from the crank angle sensor 24, the ECU 25 determines the identified cylinder group m
When the entry into the crankshaft rotation angle region corresponding to (m is 1, 2, or 3) is determined, a period measurement timer (not shown) is started, and the period until the pulse is turned off is counted. As a result, the 5 ° BTDC approaching the combustion stroke at the crank angle is changed from the 75 ° BTDC at the front of the combustion stroke.
Partial period T5 corresponding to the first rotation angle range up to DC
Is calculated (see FIG. 10 ).

Next, when the pulse is turned off, a different cycle measuring timer (not shown) is started, and the cycle until the next pulse is input is counted. This allows
The partial cycle T75 corresponding to the second rotation angle range from the crank angle of 75 ° BTDC at the front of the combustion stroke to the 5 ° BTDC at the rear of the combustion stroke is calculated (see FIG. 10 ).

When the next pulse output is input from the crank angle sensor 220, the ECU 25 determines the departure from the crankshaft rotation angle region corresponding to the identified cylinder group m, and measures the cycle for the next identified cylinder group. Therefore, the timer operation of the period measuring timer is started.

The timing results T5, T
From 75, the time interval TN (n) from the time of entry into the crankshaft rotation angle region corresponding to the identified cylinder group m to the time of departure from the region is calculated by the following equation. TN (n) = [T5 × K (Ev, Ne) + T75 × {1−K (Ev, Ne)}] × Θ where K (Ev, Ne) is a weighting coefficient, and matching is performed in advance, and A map as shown in FIG. 11 using information Ev and engine speed Ne as parameters is referred to as EC.
The value stored in U25 is read out at the time of calculating the above equation.

Therefore, the operating state of the engine 1 corresponding to the right side of the lower right characteristic of the graph (high rotation state)
, K (Ev, Ne) = 1, and the time interval T
N (n) is calculated only based on the timing result T5. In the operating state (low rotation state) of the engine 1 corresponding to the left side of the upper left characteristic of the graph, K (Ev, Ne) = 0, and the time interval TN
(N) is calculated only based on the timing result T75.

Further, in the operating state of the engine 1 corresponding to the characteristic between the lowermost rightmost characteristic and the uppermost leftmost characteristic in the graph, K (Ev, Ne) = 1 to K (Ev, Ne)
= 0, and the time interval TN (n) is proportionally divided by a required weight based on both the timing results T5 and T75.
It is to be calculated. Therefore, when the engine 1 is running at a high speed, the pulse width T5 at the front of the combustion stroke becomes dominant, and when the engine 1 is running at a high speed, the change in the combustion state is well reflected and the pulse width T5 is hardly affected by other cylinders. Is performed.

When the engine 1 is running at a low speed, the pulse width T75 in the middle of the combustion stroke becomes dominant, and at that time, the pulse width T7 in which the change in the combustion state is satisfactorily and stably reflected.
The calculation at 5 is performed. Further, when the engine 1 is rotating at a medium speed, the pulse width T5 at the front part of the combustion stroke and the pulse width T75 at the middle part of the combustion stroke are added in a required proportional division, and at this time, the change in the combustion state is reflected stably. Pulse width T75 and pulse width T5 that is less affected by other cylinders
Is calculated.

In this manner, in the entire operation range from low rotation to high rotation of the engine 1, the desired crank angle rotation period TN (n) is obtained with sufficient accuracy without being affected by other cylinders and high rotation. ) Is calculated. In addition,
By not setting an area between the lowermost rightmost characteristic and the uppermost leftmost characteristic of the graph, T5 and T75 are determined by one characteristic in which the lower right characteristic and the uppermost left characteristic are matched. You may comprise so that it may switch.

In the above equation, Θ is a correction coefficient relating to the mutual cylinder angle in the engine 1 and takes a value of “50/70” in a V6 engine and takes a value of “110/70” in a four-cylinder engine. . Here, the period TN (n)
Indicates that the cycle corresponds to the n-th (current) ignition operation in the identified cylinder.

In the case of a six-cylinder engine, the cycle TN (n) is the cycle between the 50 ° crank angles of the identified cylinder group (the time interval between the operating states BTDC of 75 ° between the adjacent cylinders). (720 /
N-70) For each cycle between the crank angles, the cycle TN
In order to calculate (n), a required number of vanes are formed, and the same calculation as above is performed.

As described above, by calculating the period TN (n) using the partial period T5 and the partial period T75,
It is possible to prevent the detection accuracy of the crank angle cycle over the entire operation range from being deteriorated due to the influence of the other cylinders, and it is possible to avoid a situation in which the detection of deterioration of combustion described later is erroneously performed. That is, when the engine reaches a high rotation state, the state of generation of a pulse corresponding to the combustion of another cylinder due to a change in ignition timing affects the crank angle cycle of the relevant cylinder, and the detection accuracy of the crank angle cycle decreases. It is expected that the influence of other cylinders will be eliminated by performing a correction for adjusting the weight of the partial cycle T5 and the partial cycle T75 on the crank angle cycle.

By the way, by the operation as described above, EC
U25 detects the 120-degree inter-crank period TN (n). A series of states from the # 1 cylinder to the # 6 cylinder is illustrated in FIG. 9 , and the 120-degree inter-crank period is TN (n). -5) to TN (n). Using these detected values, the angular acceleration AC (n) of the crankshaft in the cycle is calculated by the following equation.

AC (n) = 1 / TN (n) ｛KL (m) / TN (n) -KL
(m-1) / TN (n-1) KL where KL (m) is the segment correction value, and the period due to the variation of the vane angle interval in the vane manufacturing and installation In order to perform the correction for removing the measurement error, the ECU 25 calculates the segment correction value KL (m) by the following equation.

KL (m) = {KL (m−3) * (1-XMFDKFG) + KR (n) * (XMFDKFD)} where XMFDKFG indicates a segment correction value gain. M in KL (m) is set for each corresponding cylinder group, m = 1 for cylinder groups # 1 and # 4, m = 2 for cylinder groups # 2 and # 5, and cylinder group # 3, m = 3 corresponds respectively to # 6, FIG. 9
KL (1) to KL (3) are repeated as shown in FIG.

Since m-1 in KL (m-1) means the one immediately before the corresponding m, KL (m) = KL
When (1), KL (m-1) = KL (3), KL (m) = KL (2) When KL (m-
When 1) = KL (1) and KL (m) = KL (3), KL (m-1) = KL (2) is shown. Further, KL (m-3) in the above equation indicates the KL (m) of the previous cycle in the same cylinder group, and # 4
KL (m-3) at the time of cylinder calculation is
KL (1) is used, and KL (m-3) at the time of calculation of # 1 cylinder
Uses KL (1) in the previous # 4 cylinder. KL (m-3) at the time of calculation for # 5 cylinder is KL for the previous # 2 cylinder.
(2) is used, and KL (m-3) in the previous # 5 cylinder is used as KL (m-3) in the calculation of the # 2 cylinder. KL (m-3) in the calculation of # 6 cylinder is KL (3) in the previous # 3 cylinder
Is used, and KL (m-3) in the calculation of the # 3 cylinder uses KL (3) in the previous # 6 cylinder.

On the other hand, KR (n) in the above equation is obtained by the following equation. KR (n) = 3 ・ TN (n) / TN (n) + TN (n-1) + TN (n-2) は This is the measurement time from the previous measurement time TN (n-2) two times to the current measurement time
This is a measurement value corresponding to the average measurement time up to TN (n). When calculating the segment correction value KL (m), the primary filter processing with the segment correction value gain XMFDKFG applies the above equation to KR (n). It is performed using.

Although the segment correction is performed as described above, such a segment correction need not be performed. The angular acceleration detection means 107 is provided with a load correction means 213 for converting the calculated angular acceleration AC (n) of the crankshaft into a load correction angular acceleration ACC (n) corrected by the load of the engine 1. I have.

That is, the load correction means 213 is configured to calculate a load correction angular acceleration ACC (n) obtained by correcting the above-mentioned angular acceleration AC (n) calculated from the measured value by the following equation. ACC (n) = AC (n) / load equivalent value The load-corrected angular acceleration ACC (n) excluding the effect of the load is calculated. The fuel amount is used as the load equivalent value.

Although the illustrated effective pressure should be used as the load equivalent value, the load correction angular acceleration ACC corresponding to the load can be obtained by simple means by using the fuel amount.
(N) will be calculated.

Incidentally, the combustion state control device for the engine according to the present embodiment includes first operating state detecting means 202. The first operating state detecting means 202 is provided from the angular acceleration detecting means 107 through the load correcting means 213. The output load correction angular acceleration ACC (n) is configured to be used as it is as the first operating state parameter that fluctuates due to the inter-cylinder torque difference.

That is, the angular acceleration AC of the crankshaft
(N) represents the amount of torque generated in each cylinder. Since the load-corrected angular acceleration ACC (n) is obtained by removing the influence of the load, the value is directly generated due to the inter-cylinder torque difference. The first operating state parameter fluctuates.
The present device includes a first determination value calculation means 204, and the first determination value calculation means 204 integrates a load correction angular acceleration ACC (n) as a first operating state parameter for each cylinder, Cumulative angular acceleration value VAC1 for each cylinder
(J) is calculated.

That is, the first determination value calculating means 204
Using the load correction angular acceleration ACC (n) output from the first determination value calculation means 204, first, a combustion fluctuation value IAC1 (n) indicating a fluctuation state of the combustion state is obtained by the following equation. IAC1 (j) = − ACC (j) + IACTHV

The first combustion state determination value VAC1 (j) is obtained by comparing the load correction angular acceleration ACC (n) with a predetermined threshold value IACTHV.
The combustion state determination value VAC1 (j) is the load correction angular acceleration A
CC (n) is calculated as an accumulated amount of deterioration that is lower than the threshold value IACTHV. That is, the first combustion state determination value VAC1 (j) is calculated by the following equation.

VAC1 (j) = {ACC (j) <IACTHV}
* IAC1 (j) where {ACC (j) <IACTHV} in the above equation is ACC (j) <IA
This function takes "1" when CTHV is established and "0" when it is not established.
When (n) is below a predetermined threshold value IACTHV,
It is configured to accumulate the amount below this as the deterioration amount.

Here, the first combustion state determination value V according to the above equation
The calculation of AC1 (j) is, specifically, ACC (j) <IACTHV
Is established when the following expression is satisfied. VAC1 (j) = VAC1 (j) + IAC1 (j) This is the threshold value IACT of the load correction angular acceleration ACC (n).
When the amount below the HV is integrated for each cylinder, the integrated value is calculated from the representative value of the inter-cylinder torque difference. Is set to appear when a change occurs.

The predetermined threshold value IACTHV in the first judgment value calculating means 204 is calculated by the threshold value updating means 110.
Although it is configured to be updated according to the operating state of the engine, it may be a constant value. The threshold value IACTHV is set to “0”, and only the negative value of the load correction angular acceleration ACC (n) as the first operation state parameter is accumulated to calculate the first combustion state determination value VAC1 (j). Even with this configuration, the operations of the following combustion state determination means 212 and combustion state control means 211 can be performed without any trouble.

The above-mentioned subscript j indicates a cylinder number. The apparatus according to the present embodiment includes a combustion state determination unit 21.
The combustion state determination means 212 includes a correction coefficient KAC1 as a result of the combustion state determination using the angular acceleration cumulative value VAC1 (j) as the first combustion state determination value.
(J) is calculated.

By the way, the combustion state determining means 212
As a reference value for determination, an upper limit reference value (VACTH1V) set by the upper limit reference value setting means 112U and a lower limit reference value (VACTH2V) set by the upper limit reference value setting means 112L are read. .

The determination control in the combustion state determination means 212 and the combustion state control means 211 is performed so that the cumulative angular acceleration value VAC1 (j) falls between the upper reference value (VACTH1V) and the lower reference value (VACTH2V). It is configured to be. That is, the combustion state determination unit 212 is configured to reflect the determination result by correcting the basic injection pulse width with respect to the fuel injection control as the control by the combustion state control unit 211, and the injection pulse width Tinj (j)
Is configured to be calculated by the following equation.

Tinj (j) = TB × KAC1 (j) × KAC2 (j) × K × KAFL + Td Then, the correction coefficient KAC1 (j) in the above equation is adjusted as follows. First, the angular acceleration cumulative value VA
If C1 (j) exceeds the upper limit reference value VACTH1V, it is determined that the combustion fluctuation value has deteriorated by a predetermined amount or more, and the correction determination of the enrichment for increasing the fuel injection amount is performed by the following correction coefficient. This is performed by calculating KAC1 (j).

[0102] KAC1 (j) = KAC1 (j ) + VACK1 × {VAC1 (j) - VACTH1V (Ev, Ne)} This calculates a correction value on the rich side upper right characteristics of the correction characteristics shown in FIG. 12 Where VACK1 is a coefficient indicating the slope of the characteristic. KAC1 (j) on the right side indicates the correction coefficient calculated in the previous calculation cycle (n-1) for the cylinder number j, and is updated by the above equation.

FIG. 12 shows the cumulative angular acceleration value VA on the horizontal axis.
The correction characteristic is shown by taking C and taking the correction change amount of the combustion state determination value KAC on the vertical axis. Also, the upper reference value VACTH
1V (Ev, Ne) is Ev as load information and engine speed
A map having Ne as a parameter is stored in advance, and is set by reading a value corresponding to the operating state from the map.

The upper limit reference value VACTH1V (Ev, Ne)
Can be configured so as to correspond to the operating state of the engine using the cooling water temperature, the humidity, the battery voltage and the like of the engine as parameters. By the way, the angular acceleration cumulative value V
If AC1 (j) is lower than the lower-limit reference value VACTH2V, it is determined that there is a margin for further leaning, and the leaning correction determination for reducing the fuel injection amount is made by the following correction coefficient KAC1. (j) is calculated.

KAC1 (j) = KAC1 (j) -VACD2 This is to calculate a correction value using the lower left characteristic on the lean side shown in FIG. 12. VACD2 gradually shifts the correction coefficient KAC1 (j) to the lean side. It is a decrease. As described above, when the combustion state control is shifted to the lean side, it is not known how much the current state is maintaining the combustion state. The transfer is configured to be performed.

Further, the angular acceleration cumulative value VAC1 (j)
Is equal to or higher than the lower limit reference value VACTH2V and equal to or lower than the upper limit reference value VACTH1V, it is determined that the operating state is appropriate, and the correction coefficient KAC1 (j) is not changed in order to keep the fuel injection amount at the previous state. It has become.

This corresponds to the flat characteristic between the lower left characteristic on the lean side and the upper right characteristic on the rich side shown in FIG. 12 , and forms a dead zone for correction. Here, the lower-limit reference value VACTH2V and the upper-limit reference value VACTH1V are defined by setting the lower-limit reference value VACTH2V to (VAC0-Δ
VAC) and the upper limit reference value VACTH1V is set to (VAC0 + ΔVAC).

That is, the lower limit reference value VACTH2V is configured to be calculated by the following equation with respect to the upper limit reference value VACTH1V. VACTH2V = VACTH1V (Ev, Ne) −dead zone (2 × ΔVAC) Here, VACTH1V (Ev, Ne) is read from the map as described above.

Further, the combustion fluctuation target value VAC0 is calculated as COV (Coe
fficient of variance), which corresponds to the target value (about 10%).
By not performing fuel correction in the range of 、, rotation fluctuation can be evaluated in a finite period (128 cycles),
A limit cycle due to an error caused by calculation with a value equal to or smaller than the threshold value is prevented.

The correction coefficient KAC1 (j) is configured to be clipped at the upper and lower limits.
It is set so as to fall within the range of 0.9 <KAC1 (j) <1.1, so that rapid correction is not performed, and stable control is performed even when a failure due to a malfunction occurs. Further, the angular acceleration cumulative value VAC1
(J) is updated every set number of combustions, for example, every 128 (or 256) cycles, so that stable and reliable control reflecting statistical characteristics is performed. .

Thus, the first operating state detecting means 2
The correction of the basic injection pulse width Tinj (j) by the correction coefficient KAC1 (j) determined through the second determination value calculating means 204 and the first determination value calculating means 204 makes the control of the combustion variation element 106 through the combustion state control means 211 In the case of deterioration, the basic injection pulse width Tinj (j) is made larger to make the fuel richer, and in the case of a good combustion state, the basic injection pulse width Tinj (j) is made smaller to make the fuel richer.

On the other hand, the combustion state control device for the engine according to the present embodiment includes the second operating state detecting means 203.
The second operating state detecting means 203 is provided for the angular acceleration detecting means 10.
7 is used to detect a variation angular acceleration ΔACC (n) as a second operating state parameter that changes due to a torque variation for each cylinder.

First, the output of the angular acceleration detecting means 107 is configured to be input to the rotation information correcting means 302 so that the rotation information correcting means 302 performs noise removal correction from the detected measurement value. It is configured.
That is, the rotation information correction unit 302 calculates the noise-corrected angular acceleration ACX (n) that has been subjected to the noise removal correction by the following equation.
Is calculated.

ACX (n) = AC (n) − {AC (n + 1) + AC (n−1)} / 2 Here, the latter term on the right side of the above equation estimates the zero point at that time from the preceding and following data. AC0 (n) which was calculated, estimated by the, AC0 (n) = {AC (n + 1) + AC (n-1)} is / 2, which, as discussed in the graph in FIG. 21 , For the detected data, the AC (n
-1) and the AC (n + 1) immediately after are linearly interpolated,
It is composed of what is required at the center (as an average value). When estimating, other than the average value, AC (n-1) at the immediately preceding time point and AC (n + 1) at the immediately succeeding time point and an intermediate value can also be used.

Therefore, AC0 (n) is estimated on the waveform of the data group including the noise component, and the difference between AC0 (n) and AC (n) at the time is calculated. , A value excluding the noise component is calculated. Note that AC (n + 1) is a data value that is a unit time after the time, and AC (n) is a future value. However, the operation of a series of calculations is performed based on the measured angular velocity detected at the present time. The above operation is made possible by performing the operation in a state delayed by the unit operation cycle.

In the apparatus of this embodiment, the load correction angular acceleration ACC (n) is calculated by the load correction means 213 by correcting the noise correction angular acceleration ACX (n) calculated as described above by the following equation. It is configured to be. ACC (n) = ACX (n) / load equivalent value The load correction angular acceleration ACC (n) excluding the influence of the load is calculated. The fuel amount is used as the load equivalent value.

Although the illustrated effective pressure should be used as the load equivalent value, the load correction angular acceleration ACC corresponding to the load can be obtained by simple means by using the fuel amount.
(N) will be calculated. Although the above-described calculation is configured so that the load correction is performed after the noise removal correction, it may be configured that the noise removal correction is performed after the load correction.

Then, the calculated load correction angular acceleration AC
C (n) is configured to be input to the second operating state detecting means 203 via the smoothing means 108 so that the smoothing by the smoothing means 108 and the calculation of the second operating state parameter calculation are performed. It is configured.

That is, in the second operating state detecting means 203, the acceleration fluctuation value ΔACC (j) as the second operating state parameter is calculated by the following equation. ΔACC (j) = ACC (j) -ACCAV (j) Here, ACVAC (j) is a smoothed value obtained by smoothing the detected angular velocity by the smoothing means 108, and performs a primary filter process by the following equation. Is calculated by

ACCAV (j) = α · ACCAV (j−
1) + (1−α) · ACC (j) Here, α is an update gain in the primary filter processing, and a value of about 0.6 to 0.7 is adopted. And the second
A second determination value calculation unit 205 that calculates a second combustion state determination value VAC2 (j) using the calculation result of the operation state detection unit 203 is provided.

That is, the second determination value calculation means 205
Using the acceleration fluctuation value ΔACC (j) output from the second determination value calculating means 203, first, a combustion fluctuation value IAC2 (n) indicating the fluctuation state of the combustion state is obtained by the following equation. IAC2 (j) =-ΔACC (j) + IACTHA

Then, the acceleration variation value ΔACC (j) is compared with a predetermined threshold value IACTHA to obtain a second combustion state determination value VAC2 (j), and the second combustion state determination value VAC2 (j) is obtained. ) Is the acceleration fluctuation value ΔACC
(J) is calculated as an accumulated amount of deterioration below the threshold value IACTHA. That is, the second combustion state determination value VAC2 (j) is calculated by the following equation.

VAC2 (j) = Σ ｛ΔACC (j) <IACTHA
｝ * IAC2 (j) where ｛ΔACC (j) <IACTHA｝ in the above equation is ΔACC
(j) is a function that takes "1" when <IACTHA holds, and takes "0" when IACTHA does not hold. When the acceleration fluctuation value ΔACC (j) falls below a predetermined threshold value IACTHA, It is configured to accumulate the amount that has fallen as a deterioration amount.

Therefore, the second combustion state determination value VAC2
(J) is the threshold value IACTHA and the acceleration fluctuation value ΔACC (j)
Is obtained by accumulating the deterioration amount with the difference from the weight as a weight. The influence of the numerical value near the threshold value is reduced so that the deterioration state can be accurately reflected. The predetermined threshold value IACTHA in the second determination value calculation means 205 is configured to be updated by the threshold value update means 110 according to the operating state of the engine, but may be a constant value.

The above suffix j indicates the cylinder number. Incidentally, the second combustion state determination value VAC2 (j) calculated by the second determination value calculation unit 205 is configured to be input to the combustion state control unit 211 via the combustion state determination unit 212, and the combustion state The determination means 212 calculates the angular acceleration cumulative value VAC2 as the second combustion state determination value.
As a result of the combustion state determination using (j), a correction coefficient KAC2 (j) is calculated.

By the way, the combustion state determining means 212
The upper limit reference value (VACTH1A) set by the upper limit reference value setting means 112U and the upper limit reference value setting means 1
The lower limit value (VACTH2A) set in 12L is read. That is, the combustion variation adjustment element 1 is used for the determination by the combustion state determination control unit 211.
As the reference values for the control of 06, the upper reference value (VACTH1A) set by the upper reference value setting means 112U and the lower reference value (VACTH2) set by the upper reference value setting means 112L.
A) is provided.

Then, the control by the combustion fluctuation adjusting element 106 sets the second combustion state determination value VAC2 (j) to the upper limit reference value.
(VACTH1A) and the lower reference value (VACTH2A). That is, as described above, the control by the combustion variation adjusting element 106 is configured to be performed by correcting the basic injection pulse width at the time of fuel injection, and the injection pulse width Tinj (j) is calculated by the following equation. It is configured to:

Tinj (j) = TB × KAC1 (j) × KAC2 (j) × K × KAFL + Td Then, the correction coefficient KAC2 (j) in the above equation is adjusted as follows. First, when the second combustion state determination value VAC2 (j) exceeds the upper limit reference value VACTH1A, it is determined that the combustion fluctuation value has deteriorated by a predetermined amount or more, and the enrichment for increasing the fuel injection amount is performed. The correction is performed by calculating a correction coefficient KAC2 (j) according to the following equation.

[0129] KAC2 (j) = KAC2 (j ) + VACK2 × {VAC2 (j) - VACTH1A (Ev, Ne)} This calculates a correction value on the rich side upper right characteristics of the correction characteristics shown in FIG. 12 Here, VACK2 is a coefficient indicating the gradient of the characteristic, and is configured with a characteristic having a required gradient substantially in the same manner as VACK1, and is set by performing matching in advance. KAC2 (j) on the right side indicates the correction coefficient calculated in the previous calculation cycle (n-1) for cylinder number j, and is updated by the above equation.

In FIG. 12, the horizontal axis indicates the combustion state determination value VA.
The correction characteristic is shown by taking C and taking the correction change amount of the correction coefficient KAC on the vertical axis. Also, the upper reference value VACTH1A (Ev,
Ne) is configured such that a map using Ev as load information and the engine speed Ne as parameters is stored in advance, and a value corresponding to the operating state is read from the map.

The upper limit reference value VACTH1A (Ev, Ne)
Can be configured so as to correspond to the operating state of the engine using the cooling water temperature, the humidity, the battery voltage and the like of the engine as parameters. By the way, when the second combustion state determination value VAC2 (j) is lower than the lower limit reference value VACTH2A, it is determined that there is a margin for further leaning, and the leaning correction for reducing the fuel injection amount is performed. Is calculated by calculating the correction coefficient KAC2 (j) according to the following equation.

KAC2 (j) = KAC2 (j) -VACD2 This is for calculating a correction value by the lower left characteristic on the lean side shown in FIG. 12. VACD2 gradually shifts the correction coefficient KAC2 (j) to the lean side. It is a decrease. As described above, when the combustion state control is shifted to the lean side, it is not known how much the current state is maintaining the combustion state. The transfer is configured to be performed.

Further, the second combustion state determination value VAC2
(J) is equal to or more than the lower reference value VACTH2A and the upper reference value VACT
If it is equal to or less than H1A, it is determined that the vehicle is in an appropriate operation state, and the correction coefficient KAC2
(j) is not changed.

This corresponds to the flat characteristic between the lower left characteristic on the lean side and the upper right characteristic on the rich side shown in FIG. 12 , and constitutes a dead zone for correction. Here, the lower reference value VACTH2A and the upper reference value VACTH1A are defined by setting the lower reference value VACTH2A to (VAC0-Δ
VAC) and the upper reference value VACTH1A is set to (VAC0 + ΔVAC).

That is, the lower limit reference value VACTH2A is configured to be calculated by the following equation with respect to the upper limit reference value VACTH1A. VACTH2A = VACTH1A (Ev, Ne) −dead zone (2 × ΔVAC) Here, VACTH1A (Ev, Ne) is read from the map as described above.

Further, the combustion fluctuation target value VAC0 is calculated as COV (Coe
fficient of variance), which corresponds to the target value (about 10%).
By not performing fuel correction in the range of 、, rotation fluctuation can be evaluated in a finite period (128 cycles),
A limit cycle due to an error caused by calculation with a value equal to or smaller than the threshold value is prevented.

The correction coefficient KAC2 (j) is configured to be clipped at the upper and lower limits.
It is set so as to fall within the range of 0.9 <KAC2 (j) <1.1, so that rapid correction is not performed, and stable control is performed even when a failure due to a malfunction occurs. Further, the second combustion state determination value VAC
2 (j) is updated every set number of combustions, for example, every 128 (or 256) cycles, so that stable and reliable control reflecting statistical characteristics is performed. I have.

Thus, the second operating state detecting means 2
03 and the correction coefficient KAC2 (j) determined through the second determination value calculation means 205 to correct the basic injection pulse width Tinj (j), thereby controlling the combustion fluctuation adjustment element 106 via the combustion state determination control means 211. When the combustion deteriorates, the basic injection pulse width Tinj (j) is increased to enrich the fuel, and when the combustion is good, the basic injection pulse width Tinj (j) is decreased to perform the lean fuel injection. .

Since the combustion state control device according to one embodiment including the combustion state determination device for an internal combustion engine according to the present invention is configured as described above, during the lean burn operation,
The operations shown in the flowcharts of FIGS. First, in step S1V, the angular acceleration AC (n) is detected by the angular acceleration detecting means 107.

Here, the calculation used for detection is based on the following equation. AC (n) = 1 / TN (n) · ｛KL (m) / TN (n) -KL (m-1) / TN (n-
1) TN By the way, TN (n) and TN (n-1) in this equation are obtained as follows. That is, while the engine is running, the ECU
A pulse output 25 from the crank angle sensor 24 and a detection signal from the cylinder discrimination sensor 230 are sequentially input, and the calculation is periodically repeated.

The ECU 25 is provided with a crank angle sensor 2
Then, it is determined which of the pulse outputs from the cylinders 4 is sequentially input after the pulse output from the cylinder determination sensor 230 is input. Thereby, the input pulse output from the crank angle sensor 24 is identified as to which cylinder it corresponds to, and preferably,
The cylinder that is currently mainly performing the expansion stroke (output stroke: BTDC 75 °) is identified as the identification cylinder.

Then, in response to the pulse input from the crank angle sensor 24, the ECU 25 determines the identified cylinder group m
When the entry into the crankshaft rotation angle region corresponding to (m is 1, 2, or 3) is determined, a period measurement timer (not shown) is started, and the period until the pulse is turned off is counted. As a result, the 5 ° BTDC approaching the combustion stroke at the crank angle is changed from the 75 ° BTDC at the front of the combustion stroke.
Partial period T5 corresponding to the first rotation angle range up to DC
Is calculated (see FIG. 10 ).

Next, when the pulse is turned off, a different cycle measuring timer (not shown) is started, and the cycle until the next pulse is input is measured. This allows
The partial cycle T75 corresponding to the second rotation angle range from the crank angle of 75 ° BTDC at the front of the combustion stroke to the 5 ° BTDC at the rear of the combustion stroke is calculated (see FIG. 10 ).

When the next pulse output is input from the crank angle sensor 220, the ECU 25 determines the departure from the crankshaft rotation angle region corresponding to the identified cylinder group m, and measures the cycle for the next identified cylinder group. Therefore, the timer operation of the period measuring timer is started.

The timing results T5, T
From 75, the time interval TN (n) from the time of entry into the crankshaft rotation angle region corresponding to the identified cylinder group m to the time of departure from the region is calculated by the following equation. TN (n) = [T5 × K (Ev, Ne) + T75 × {1−K (Ev, Ne)}] × Θ where K (Ev, Ne) is a weighting coefficient, and matching is performed in advance, and A map as shown in FIG. 11 using information Ev and engine speed Ne as parameters is referred to as EC.
The value stored in U25 is read out at the time of calculating the above equation.

Therefore, in the operating state of the engine 1 corresponding to the right side of the lower right characteristic in the graph, K
(Ev, Ne) = 1, and the time interval TN (n) is calculated only based on the timing result T5. Further, in the operating state of the engine 1 corresponding to the left side of the upper left characteristic of the graph, K (Ev, Ne) = 0, and the time interval T
N (n) is calculated only based on the timing result T75.

Further, in the operating state of the engine 1 corresponding to the characteristic between the lowermost rightmost characteristic and the uppermost leftmost characteristic in the graph, K (Ev, Ne) = 1 to K (Ev, Ne)
= 0, and the time interval TN (n) is calculated by proportionally dividing the time interval TN (n) by a required weight based on both the timing results T5 and T75. Therefore, when the engine 1 is running at a high speed, the pulse width T5 at the front of the combustion stroke becomes dominant, and when the engine 1 is running at a high speed, the change in the combustion state is well reflected and the pulse width T5 is hardly affected by other cylinders. Is performed.

When the engine 1 is running at a low speed, the pulse width T75 in the middle of the combustion stroke becomes dominant, and at this time, the pulse width T7 in which the change in the combustion state is reflected stably.
The calculation at 5 is performed. Further, when the engine 1 is rotating at a medium speed, the pulse width T5 at the front part of the combustion stroke and the pulse width T75 at the middle part of the combustion stroke are added in a required proportional division, and at this time, the change in the combustion state is reflected stably. Pulse width T75 and pulse width T5 that is less affected by other cylinders
Is calculated.

As described above, in the entire operation range from low rotation to high rotation of the engine 1, the desired crank angle rotation period TN (n) is obtained with sufficient accuracy without being affected by other cylinders and high rotation. ) Is calculated. In addition,
Θ in the above equation is a correction coefficient related to the mutual cylinder angle in the engine 1 and takes a value of “50/70” in the V6 engine.

Here, the subscript n in the cycle TN (n)
Indicates that the cycle corresponds to the n-th (current) ignition operation in the identification cylinder. Then, the aforementioned AC (n)
KL (m) in the calculation formula of the above is a segment correction value, and in order to perform a correction for removing a cycle measurement error due to a variation in a vane angle interval in vane manufacturing and installation, in connection with the present identification cylinder, The segment correction value KL (m) is calculated by the following equation.

KL (m) = {KL (m−3) * (1-XMFDKFG) + KR (n) * (XMFDKFD)} where XMFDKFG indicates a segment correction value gain. On the other hand, KR (n) in the above equation is obtained by the following equation. KR (n) = 3 ・ TN (n) / TN (n) + TN (n-1) + TN (n-2) は This is the measurement time from the previous measurement time TN (n-2) two times to the current measurement time
This is a measurement value corresponding to the average measurement time up to TN (n). In calculating the segment correction value KL (m), the primary filter processing using the segment correction value gain XMFDKFG is performed using the above-described equation.

Next, at step S3V, the angular acceleration A of the crankshaft calculated by the angular acceleration detecting means 107 is calculated.
An operation for converting C (n) into a load correction angular acceleration ACC (n) corrected by the load of the engine 1 by the load correction means 213 is performed. That is, the load correction means 213 calculates a load correction angular acceleration ACC (n) obtained by correcting the above-described angular acceleration AC (n) calculated from the measured value by the following equation.

ACC (n) = AC (n) / load equivalent value Thus, the load-corrected angular acceleration ACC (n) excluding the influence of the load is calculated. Here, the fuel amount is used as the load equivalent value in the above equation. As the load equivalent value,
Although the illustrated effective pressure should be used, the load correction angular acceleration ACC (n) corresponding to the load is calculated by a simple means by using the fuel amount.

Next, step S4V is executed, and the first
In the driving state detecting means 202, the angular acceleration detecting means 1
The load correction angular acceleration ACC (n) output from the load correction means 213 via the load correction means 213 is adopted as a first operating state parameter that fluctuates due to the inter-cylinder torque difference. That is, the angular acceleration AC (n) of the crankshaft represents the amount of torque generated in each cylinder, and the load correction angular acceleration ACC
Since (n) removes the influence of the load, the value is directly used as the first operating state parameter that fluctuates due to the inter-cylinder torque difference.

Then, steps S7V to S10
V is executed, and the first determination value calculation means 204 executes the load correction angular acceleration ACC as the first operation state parameter.
(N) is integrated for each cylinder, and the operation of calculating the angular acceleration cumulative value VAC1 (j) for each cylinder is performed. First, in step S7V, the first determination value calculating means 20
The combustion variation value IAC1 indicating the variation state of the combustion state using the load correction angular acceleration ACC (n) output from
(N) is obtained by the following equation.

IAC1 (j) = − ACC (j) + IACTHV

In step S8V, a comparison between the load correction angular acceleration ACC (n) and the predetermined threshold value IACTHV is made based on the positive / negative judgment of the combustion fluctuation value IAC1 (n). , Step S10V is executed. Further, the combustion fluctuation value IAC1
If (n) is negative, step S9V is executed through the "YES" route.

At step S9V, the combustion fluctuation value IAC1
(N) is replaced with “0”. Then, step S
At 10 V, the first combustion state determination value VAC according to the following equation
1 (j) is calculated. VAC1 (j) = VAC1 (j) + IAC1 (j) As a result, the load correction angular acceleration ACC (n) becomes equal to the threshold value IA.
The amount below CTHV is integrated for each cylinder, and an integrated value representing the inter-cylinder torque difference is calculated. The variation of the load correction angular acceleration ACC (n) in the direction in which combustion is good is determined to be "0" in step S9V. , The cumulative result indicates combustion deterioration.

As described above, the first combustion state determination value VA
C1 (j) is calculated. This calculation is obtained by executing the following equation.

VAC1 (j) = {ACC (j) <IACTHV}
* IAC1 (j) where {ACC (j) <IACTHV} in the above equation is ACC (j) <
This function takes "1" when IACTHV is established, and takes "0" when it is not established. Thus, when the load correction angular acceleration ACC (n) is lower than the predetermined threshold value IACTHV, the amount of decrease is accumulated as the deterioration amount.

[0161] That is, as shown in point A~D in Figure 13, the load correction angle acceleration ACC (n) is a predetermined threshold value IAC
When the value is below the THV, the amount below the THV is accumulated as the deterioration amount. Then, the combustion deterioration determination value V
AC1 (j) is the threshold value IACTHV and the load correction angular acceleration AC
The deterioration amount is obtained by accumulating the deterioration amount with the difference from C (n) as a weight, and the influence of the numerical value near the threshold value is reduced, and the deterioration state is accurately reflected on the combustion deterioration determination value VAC1 (j).

Further, the cumulative value does not fluctuate greatly when intermittent misfires occur, but fluctuates when continuous misfires occur. Therefore, the determination of deterioration of combustion due to continuous misfires in the steps described later is reliably performed. It will be.

The predetermined threshold value IACTHV in the calculation in step S7V is updated by the threshold update means 110 in accordance with the operating state of the engine, and the above-described calculation is performed so that the operating state closer to the lean limit can be realized. Done. Further, the threshold value IACTHV is set to “0”, and the load correction angular acceleration ACC (n) as the first operating state parameter is set.
Of the first combustion state VAC1
Even in the case of calculating (j), the above-described calculation is performed without any trouble, and the following operations of the combustion state determination unit 212 and the combustion state control unit 211 are performed.

Then, the operation according to the flowchart of FIG. 5 is performed using the above-described calculation result. First, step S11V is executed, and it is determined whether or not n indicating the number of times of sampling exceeds 128. That is, FIG. 1
It is determined whether or not the accumulation section shown in FIG. 3 has elapsed, and if not, the “NO” route is taken and step S
Step SS3 (see FIG. 8) is executed without performing fuel correction by increasing the number n by “1” by executing 13V. As a result, the correction coefficient KAC1 in the injection pulse width Tinj for the 128-cycle integration section
The correction relating to (j) is not performed, and the accumulation of the angular acceleration cumulative value VAC1 (j) as the first combustion state determination value is performed exclusively.

Therefore, the cumulative angular acceleration value VAC1 (j) as the first combustion state determination value is updated every set combustion number, for example, every 128 cycles, and reflects statistical characteristics. Stable and reliable control is performed. Then, when the accumulation section has elapsed, the process proceeds to step S12V through the “YES” route of step S11V.
Step S19V is executed.

First, in step S12V, the number n
Is reset to “1”, and then in steps S14V and S16V, the angular acceleration accumulated value VAC1
Referring to (j), the comparison with the predetermined reference value set by the reference value setting means 112 is performed as an operation of the combustion state determination means 212. First, the angular acceleration cumulative value VAC1
Comparison with (j) and the upper-limit reference value (VACTH1V) is performed, when the angular acceleration cumulative value VAC1 to (j) exceeds the upper limit reference value VACTH1V, i.e., as shown in FIG. 14, deterioration of combustion variation If the angular acceleration cumulative value VAC1 (j) exceeds the upper limit reference value VACTH1V, which is the limit, in step S15V, a correction coefficient KAC1 (j) is calculated by the following equation.

[0167] KAC1 (j) = KAC1 (j ) + KAR · {VAC1 (j) - VACTH1V (Ev, Ne)} This is for calculating the correction value on the rich side upper right characteristics shown in FIG. 12, or predetermined Assuming that the combustion fluctuation value is worse, the correction of the enrichment to increase the fuel injection amount is performed by calculating the correction coefficient KAC1 (j). Here, KAR is a coefficient indicating the slope of the characteristic,
KAC1 (j) on the right side indicates the correction coefficient calculated in the previous calculation cycle (n-1) for the cylinder number j,
Update is performed by the above equation.

If the angular acceleration cumulative value VAC1 (j) is lower than the lower limit reference value VACTH2V, step S
Assuming that the "YES" route is taken at 16V and there is room for further leaning, the leaning correction for reducing the fuel injection amount is performed by calculating the correction coefficient KAC1 (j) according to the following equation. KAC1 (j) = KAC1 (j)-KAL ｛VAC1 (j)-VACTH2V (Ev, Ne)｝ This calculates the correction value of the lower left characteristic on the lean side shown in Fig. 12 , where KAL is the slope of the characteristic. Is a coefficient indicating

Further, the angular acceleration cumulative value VAC1 (j)
Is equal to or higher than the lower reference value VACTH2V and the upper reference value VACTH1V (E
v, Ne) or less, the steps S14V and S16V both take the “NO” route, determine that the vehicle is in an appropriate operating state, and maintain the fuel injection amount in the previous state, so that the correction coefficient KAC1 (j ) Is not changed.
This corresponds to a flat characteristic between the lean lower left characteristic and the rich upper right characteristic shown in FIG. 12 , and constitutes a dead zone for correction.

Here, the lower limit reference value VACTH2V and the upper limit reference value
VACTH1V means the lower limit reference value VACTH2V to the value of (VAC0-ΔVAC) and the upper limit reference value VACTH1
V is set to the value of (VAC0 + ΔVAC). The target combustion variation value VAC0 is the target value of COV (Coefficient of variance).
(Approximately 10%) and the target value of the combustion fluctuation VAC0
By not correcting the fuel in the range of ΔVAC on both sides of the motor, the rotation fluctuation is evaluated in a finite period (128 cycles), and the limit cycle due to the error caused by the calculation using a value less than the threshold is prevented. Is done.

Then, step S18V is executed, and the angular acceleration cumulative value VAC1 (j) is reset to "0". Further, in step S19V, the correction coefficient KAC1
If (j) exceeds the upper and lower limit values, it is clipped to the limit value on the exceeded side. For example, 0.9 <KAC1 (j) <
If the calculated value in step S15V exceeds 1.1, the value is set to 1.1, and if the calculated value in step S16V is less than 0.9, the value is set to 0.9. Is set.

As a result, rapid control is not performed, and stable control is performed even when a failure due to a malfunction occurs. Then, the operation of the flowchart shown in FIG. 8 is performed in a predetermined calculation cycle, the correction coefficient KAC1 (j) calculated by the above-described calculation is read in step SS1, and the correction coefficient KAC2 (j) described later is further corrected in step SS2. In step SS3, the basic injection pulse width at the time of fuel injection is corrected using the correction coefficient KAC1 (j) determined as described above and a correction coefficient KAC2 (j) described later.

That is, the injection pulse width Tinj (j) is calculated by the following equation.

Tinj (j) = TB × KAC1 (j) × KAC2 (j) × K × KAFL + Td By the correction of the basic injection pulse width, the combustion state control means 211 controls the combustion fluctuation adjusting element 106. , The engine leans to the desired lean operating condition. Note that control of the ERG amount may be considered as the combustion adjustment element. By the way, in the operation of the flowchart shown in FIG. 6, first, in step S1A, the angular acceleration detection means 107 detects the angular acceleration AC (n).

Here, the calculation used for detection is based on the following equation. AC (n) = 1 / TN (n) · ｛KL (m) / TN (n) -KL (m-1) / TN (n-
1) と こ ろ で By the way, the calculation of this expression is performed in the same manner as the operation in step S1V described above. Then, step S2
In A, noise removal correction is performed from the detected measurement value.

That is, the noise-corrected angular acceleration ACX (n) subjected to the noise removal correction is calculated by the following equation. ACX (n) = AC (n)-{AC (n + 1) + AC (n-1)} / 2 Here, the latter term on the right side of the above equation was obtained by estimating the zero point at that time from the preceding and following data. but was estimated AC0 (n) is, AC0 (n) = {AC (n + 1) + AC (n-1)} is / 2, which, as discussed in the graph in FIG. 21, is detected Data (AC (n
-1) and the AC (n + 1) immediately after are linearly interpolated,
It is found at the center (as an average).

Therefore, AC0 (n) is estimated on the waveform of the data group including the noise component, and the difference between AC0 (n) and AC (n) at the time is calculated. , A value excluding the noise component is calculated. Here, considering the relationship between the detection signal of the noise and angular acceleration AC (n), the drive system resonance of the engine 1 has occurred as shown in FIG. 16, in the presence of such a resonance, Fig. As shown in FIG. 17 , a signal for detecting a decrease in rotation due to combustion deterioration is generated.

[0178] variation caused by the driving system resonance of the engine 1 (noise) is generated as a component as shown in FIG. 18,
When this noise is combined with a signal to be detected for a decrease in rotation due to deterioration of combustion as shown in FIG. 17 , a state as shown in FIG. 19 is obtained. In this state, as shown in FIG. 20 , even if the rotation has decreased due to the deterioration of combustion, it is impossible to identify and detect the rotation with a certain threshold.

Therefore, the angular acceleration AC (n) is to be detected by calculating the signal deviation from the zero point on the transition of the noise group, whereby the noise removal correction is performed. After that, the state of data as shown in FIG. 22 is obtained, and the data whose rotation has decreased due to deterioration of combustion can be identified and detected by a certain threshold value.

A vane 2 used for detecting rotation fluctuations
FIG. 23 shows a segment correction for correcting an error generated due to the shape accuracy of 21A, 221B, 221C.
With respect to the data of (1), data whose rotation has decreased due to deterioration of combustion can be identified and detected by a certain threshold value. Note that AC (n + 1) is a data value that is a unit time after the time, and is a future value for AC (n). It is performed in a state delayed by the unit operation cycle.

Next, in step S3A, the noise-corrected angular acceleration ACX (n) subjected to the noise elimination correction.
Is converted into a load correction angular acceleration ACC (n) corrected by the load of the engine 1 by the load correction means 213. That is, the load correction means 213 calculates a load correction angular acceleration ACC (n) obtained by correcting the above-described angular acceleration ACX (n) calculated from the measured value by the following equation.

ACC (n) = ACX (n) / equivalent load value The load-corrected angular acceleration ACC (n) excluding the influence of the load is calculated. Here, the fuel amount is used as the load equivalent value in the above equation. As the load equivalent value,
Although the illustrated effective pressure should be used, the load correction angular acceleration ACC (n) corresponding to the load is calculated by a simple means by using the fuel amount.

Next, step S4A is executed, and the average acceleration ACCAV (n) is calculated. Where ACC
AV (n) is a smoothed value obtained by smoothing the detected angular velocity ACC (n) by the smoothing means 108, and is calculated by performing a primary filtering process according to the following equation.

ACVAC (n) = α · ACCAV (n−
1) + (1−α) · ACC (n) Here, α is an update gain in the primary filter processing, and a value of about 0.95 is adopted.

Next, in step S6A, the second operating state detecting means 203 detects an acceleration fluctuation value ΔACC (n) as a second operating state parameter. That is, by calculating the difference between the angular velocity ACC (n) detected by the angular acceleration detecting means 107 and the average acceleration ACVAC (n) as a smoothed value smoothed by the smoothing means 108, the acceleration variation value ΔACC (n ) Is calculated by the following equation.

ΔACC (n) = ACC (n) −ACCAV (n) That is, the angular acceleration AC (n) of the crankshaft represents the amount of torque generated in each cylinder, and the load correction angular acceleration AC
Since C (n) removes the influence of the load, the load correction angular acceleration ACC (n) is a second operating state parameter that changes due to the amount of torque fluctuation.

Here, as in the present embodiment, calculation of the average acceleration ACVAC (j) in step S4A,
By performing the calculation of the acceleration variation value ΔACC (j) in step S6A, the above-described segment correction is automatically performed, and the vanes 221A, 221B, and 221C are performed.
The effect of the shape error is avoided. Then, step S7
A to step S10A are executed, and the second determination value calculation means 205 accumulates the acceleration fluctuation value ΔACC (j)) as the second operating state parameter for each cylinder, and obtains the second combustion state determination value for each cylinder. Is performed to calculate the fluctuation acceleration cumulative value VAC2 (j) as the following.

First, in step S7A, the acceleration fluctuation value ΔAC output from the second operating state detecting means 203
Using C (j), a combustion fluctuation value IAC2 (n) indicating a fluctuation state of the combustion state is obtained by the following equation. IAC2 (j) =-ΔACC (j) + IACTHA

Then, in step S8A, a comparison between the acceleration fluctuation value ΔACC (j) and the predetermined threshold value IACTHA is made by determining whether the combustion fluctuation value IAC2 (n) is positive or negative. Step S10A is executed. Further, the combustion fluctuation value IAC2
If (n) is negative, step S9A is executed through the "YES" route.

At step S9A, the combustion fluctuation value IAC2
(N) is replaced with “0”. Then, step S
At 10A, a variation acceleration cumulative value VAC2 (j) as a second combustion state determination value is calculated by the following equation. VAC2 (j) = VAC2 (j) + IAC2 (j) As a result, the acceleration fluctuation value ΔACC (j) becomes equal to the threshold value IAC.
The amount below THA is integrated for each cylinder, and an integrated value representing the torque fluctuation amount is calculated. The change in the acceleration fluctuation value ΔACC (j) in the direction in which combustion is good is determined in step S9.
Since V is set to “0”, the cumulative result indicates combustion deterioration.

As described above, the cumulative acceleration value VAC
2 (j) is calculated, and this calculation is obtained by executing the following equation.

VAC2 (j) = Σ ｛ΔACC (j) <IACTHV
A｝ * IAC2 (j) where ｛Δ ACC (j) <IACTHA ｛is ΔACC (j)
<This function takes "1" when IACTHA is satisfied and "0" when it is not. As a result, when the acceleration variation value ΔACC (j) is below the predetermined threshold value IACTHA, the amount below this value is accumulated as the deterioration amount.

That is, as shown by points A to D in FIG. 13 , the combustion fluctuation value IAC2 (n) is equal to the predetermined threshold value IACTH.
When the value is below A, the amount below this is accumulated as a deterioration amount. Then, the fluctuation acceleration cumulative value VA
C2 (j) is the threshold value IACTHA and the acceleration variation value ΔACC
(J) is calculated by accumulating the amount of deterioration with the difference from
The influence of the numerical value near the threshold is reduced, and the deterioration state is accurately reflected on the fluctuation acceleration cumulative value VAC2 (j).

Further, the cumulative value does not fluctuate greatly when intermittent misfires occur, but fluctuates when continuous misfires occur. Therefore, the determination of deterioration of combustion due to continuous misfires in the steps described later is reliably performed. It will be.

The predetermined threshold value IACTHA in the calculation in step S7A is updated by the threshold value updating means 110 in accordance with the operating state of the engine, and the above-described calculation is performed so that the operating state closer to the lean limit can be realized. Done. Further, the threshold value IACTHA is set to “0”, and only the positive value of the acceleration fluctuation value ΔACC (j) as the second operating state parameter is accumulated to accumulate the fluctuation acceleration VAC2 (j) as the second combustion state determination value. Is calculated without any trouble, the following operations of the combustion state determination means 212 and the combustion state control means 211 are performed.

The operation according to the flowchart of FIG. 7 is performed using the above-described calculation result. First, step S11A is executed, and it is determined whether or not n indicating the number of times of sampling exceeds 128. That is, FIG. 1
It is determined whether or not the accumulation section shown in FIG. 3 has elapsed, and if not, the “NO” route is taken and step S
13A, the number n is increased by "1", and step SS3 (see FIG. 8) is executed without performing fuel correction. As a result, the correction coefficient KAC2 in the injection pulse width Tinj within the integration period of 128 cycles
The correction relating to (j) is not performed, and the cumulative fluctuation acceleration value VAC2 (j) as the second combustion state determination value is exclusively accumulated.

Therefore, the fluctuation acceleration cumulative value VAC2 (j) as the second combustion state determination value is updated every set number of times of combustion, for example, every 128 cycles, and reflects statistical characteristics. Stable and reliable control is performed. When the accumulation section has elapsed, the process proceeds to step S12A through the “YES” route of step S11A.
Step S19A is executed.

First, in step S12A, the number n
Is reset to “1”. Then, in steps S14A and S16A, the fluctuation acceleration accumulated value VAC
2 (j), the comparison with the predetermined reference value set by the reference value setting means 112 is performed as an operation of the combustion state determination means 212. First, the fluctuation acceleration cumulative value VAC2
Comparison of (j) as the upper limit reference value (VACTH1A) is performed, when the change acceleration cumulative value VAC2 to (j) exceeds the upper limit reference value VACTH1A, i.e., as shown in FIG. 14, deterioration of combustion variation Acceleration fluctuation value VAC2 (j) as
Exceeds the upper limit, VACTH1A, which is the limit.
In step S15A, the correction coefficient KAC2 according to the following equation
(j) is calculated.

[0199] KAC2 (j) = KAC2 (j ) + KAR · {VAC2 (j) - VACTH1A (Ev, Ne)} This is for calculating the correction value on the rich side upper right characteristics shown in FIG. 12, or predetermined Assuming that the combustion fluctuation value is worse, the correction of the enrichment for increasing the fuel injection amount is performed by calculating the correction coefficient KAC2 (j). Here, KAR is a coefficient indicating the slope of the characteristic,
KAC2 (j) on the right side shows the correction coefficient calculated in the previous calculation cycle (n-1) for the cylinder number j,
Update is performed by the above equation.

When the fluctuation acceleration cumulative value VAC2 (j) is lower than the lower limit reference value VACTH2A, it is assumed that the "YES" route is taken in step S16A, and that there is a margin for further leaning. The lean correction for reducing the fuel injection amount is performed by calculating a correction coefficient KAC2 (j) according to the following equation. KAC2 (j) = KAC2 (j)-KAL ｛VAC2 (j)-VACTH2A (Ev, Ne)｝ This calculates the correction value of the lean lower left characteristic shown in Fig. 12 , where KAL is the characteristic slope. Is a coefficient indicating

Further, the fluctuation acceleration cumulative value VAC2 (j)
Is equal to or higher than the lower reference value VACTH2A and the upper reference value VACTH1A (E
v, Ne) When it is equal to or less than the above, in step S14A and step S16A, the correction coefficient KAC2 is used in order to take the “NO” route and maintain the fuel injection amount in the previous state assuming that the operating state is appropriate. (j) is not changed.

This corresponds to the flat characteristic between the lower left characteristic on the lean side and the upper right characteristic on the rich side shown in FIG. 12 and constitutes a dead zone for correction.

Here, the lower reference value VACTH2A and the upper reference value
VACTH1A means the lower limit reference value VACTH2A to the value of (VAC0-ΔVAC) and the upper limit reference value VACTH1 around the combustion fluctuation target value VAC0.
A is set to the value of (VAC0 + ΔVAC). The target combustion variation value VAC0 is the target value of COV (Coefficient of variance).
(Approximately 10%) and the target value of the combustion fluctuation VAC0
By not correcting the fuel in the range of ΔVAC on both sides of the motor, the rotation fluctuation is evaluated in a finite period (128 cycles), and the limit cycle due to the error caused by the calculation using a value less than the threshold is prevented. Is done.

Then, step S18A is executed, and the fluctuation acceleration cumulative value VAC2 (j) is reset to "0". Further, in step S19A, the correction coefficient KAC2
If (j) exceeds the upper and lower limit values, it is clipped to the limit value on the exceeded side. For example, 0.9 <KAC2 (j) <
If the calculated value in step S15A exceeds 1.1, the value is set to 1.1, and if the calculated value in step S16A falls below 0.9, the value is set to 0.9. Is set.

As a result, rapid control is not performed, and stable control is performed even when a failure occurs due to a malfunction. Then, the operation of the flowchart shown in FIG. 8 is executed in a predetermined operation cycle, but the correction coefficient KAC1 (j) calculated in the above operation is read in step SS1, and the correction coefficient KAC1 (j) calculated in the above operation is further read. Coefficient KAC2
(j) is read in step SS2, and then in step SS3, the basic injection pulse width at the time of fuel injection is corrected by the correction coefficients KAC1 (j) and KAC2 (j) determined as described above.

That is, the injection pulse width Tinj (j) is calculated by the following equation.

Tinj (j) = TB × KAC1 (j) × KAC2 (j) × K × KAFL + Td By the correction of the basic injection pulse width, the combustion state control means 211 controls the combustion fluctuation adjusting element 106, The engine leans against the desired lean operating condition. Note that control of the ERG amount may be considered as the combustion adjustment element .

[0208]

[0209]

[0210]

[0211]

[0212]

[0213]

[0214] The Contact, from the first operating parameter when determining the first combustion state determination value, with respect to the angular acceleration ACC (n), performs a zero point correction may be subjected to a noise removal correction. In this case, the process of step S2A of FIG. 6 is performed after the process of step S1V of FIG.

The operation is performed as described above. According to the present embodiment, the following effects and advantages are obtained. (1) During lean-burn operation, taking into account the probability and statistical properties of combustion fluctuations, it is possible to perform reliable combustion control, in particular, reliable combustion control for each cylinder that can cope with both continuous and intermittent misfires. become.

(2) It is possible to avoid imbalance in output between cylinders due to continuous misfire, and to perform control corresponding to deterioration of the driving feeling due to intermittent misfire. (3) During lean burn operation, control based on the rotational angular acceleration of the internal combustion engine can be performed, and control can be performed to avoid imbalance in output between cylinders due to continuous misfire.

(4) During lean burn operation, control based on the change in the rotational angular acceleration of the internal combustion engine can be performed, and control can be performed in response to the deterioration of the driving feeling caused by the intermittent misfire. Become. (5) During lean-burn operation, control based on the rotational angular acceleration of the internal combustion engine can be performed, and control for avoiding imbalance in inter-cylinder output due to continuous misfire can be performed by controlling the rotational speed and load of the internal combustion engine. Will be performed reliably in response to

(6) During lean burn operation, the control based on the change in the rotational angular acceleration of the internal combustion engine can be reliably performed in response to misfire, and the deterioration in driving feeling due to intermittent fire can be addressed. This control is reliably performed in accordance with the rotational speed and load of the internal combustion engine.

[0219]

As described above in detail, according to the combustion state determining apparatus for an engine according to the first aspect of the present invention, the first operation which fluctuates due to the inter-cylinder torque difference of the internal combustion engine having a plurality of cylinders. First operating state detecting means for detecting a state parameter, and integrating the first operating state parameter detected by the first operating state detecting means for each cylinder to calculate a first combustion state determination value for each cylinder A first determination value calculating means, a second operating state detecting means for detecting a second operating state parameter which changes due to a torque change for each cylinder of the internal combustion engine, and a detecting means for detecting the second operating state parameter. A second determination value calculating means for integrating the second operating state parameter obtained for each cylinder to calculate a second combustion state determination value for each cylinder; and
A combustion state determining means for determining a combustion state of the internal combustion engine based on both the second combustion state determination value calculated by integrating the first combustion state determination value and the second judgment value calculating means being further calculated With such a simple configuration, the following effects or advantages can be obtained.

[0220] (1) during lean burn operation, taking into account the probability and statistical properties of combustion variation, reliable combustion control, reliable combustion control for each cylinder which may correspond to a particular bi towards the continuous misfire and intermittent misfire Can be done. (2) It is possible to avoid imbalance in the inter-cylinder output caused by the continuous misfire, and to perform control corresponding to the deterioration of the driving feeling caused by the intermittent misfire.

According to a second aspect of the present invention, in the first aspect, the first operating state detecting means may include the first operating state parameter as the first operating state parameter. With a simple configuration that is configured to detect angular acceleration, during lean burn operation,
Control based on the rotational angular acceleration of the internal combustion engine can be performed, and control for avoiding imbalance in the inter-cylinder output due to continuous misfire can be performed.

[0222] Further, the apparatus 請 Motomeko 2, wherein the rotational angular acceleration of the internal combustion engine detected by said first operation state detection means is provided <br/> means for correcting the load information of the internal combustion engine In the case (aspect 1), the calculation logic for calculating the first combustion state determination value is simplified. According to a third aspect of the present invention, there is provided the internal combustion engine combustion state determining apparatus, wherein the second operating state detecting means includes the rotational angular acceleration change of the internal combustion engine as the second operating state parameter. With a simple configuration that is configured to detect the amount, during lean burn operation, control based on the amount of change in the rotational angular acceleration of the internal combustion engine can be performed, and the driving feeling due to intermittent fire can be reduced. The control corresponding to the deterioration can be performed.

[0223] Then, the device 請 Motomeko 1, wherein said second operation state detection means, the deviation from the smoothed value of the rotational angular acceleration detected so far in the rotational angular acceleration of the internal combustion engine When the configuration is such that the rotational angular acceleration change amount is obtained based on the above (aspect 2), with such a simple configuration, the rotational angular acceleration change amount of the internal combustion engine can be calculated during lean burn operation. You can control the basics,
The control corresponding to the deterioration of the driving feeling caused by the intermittent fire can be performed.

Further, in the apparatus according to the second aspect, when means for correcting the actually measured value of the rotational angular acceleration of the internal combustion engine with the load information of the internal combustion engine is provided (aspect 3), the second combustion state The calculation logic for calculating the judgment value is simplified. Further, the determination of the combustion state of the internal combustion engine according to claim 4 is performed.
According to the device, the device according to claim 3 is the second device.
With a simple configuration in which the determination value calculation means integrates only the rotation angular acceleration change amount having a negative value, the control based on the rotation angular acceleration change amount of the internal combustion engine is misfired during lean burn operation. , And control corresponding to the deterioration of the driving feeling caused by the intermittent misfire can be reliably performed.

Further, according to the combustion state determining apparatus of the fifth aspect, the combustion state determining means of the apparatus according to the first aspect is obtained by integrating the combustion state determining means by the first determination value calculating means. (1) A simple configuration in which the combustion state determination value is compared with a first predetermined value to determine that continuous misfire has occurred in the cylinder. Control based on angular acceleration can be performed, and control for avoiding imbalance in output between cylinders due to continuous misfire can be reliably performed.

In the apparatus according to the fifth aspect , when the combustion state determining means is configured to set the first predetermined value based on an operation state of the internal combustion engine (state 4). In this simple configuration, control based on the rotational angular acceleration of the internal combustion engine can be performed during lean burn operation, and control for avoiding imbalance in the inter-cylinder output due to continuous misfires is performed. The operation is reliably performed according to the operating state of the engine.

In the apparatus according to the fourth aspect, when the combustion state determining means is configured to set the first predetermined value based on the rotation speed and the load of the internal combustion engine (aspect 5 ). With such a simple configuration, during lean burn operation, control based on the rotational angular acceleration of the internal combustion engine can be performed, and control for avoiding imbalance in inter-cylinder output due to continuous misfire is performed. This is performed reliably in accordance with the number and the load.

[0228] According to the combustion state judging device of the internal combustion engine according to the sixth aspect, the combustion state judging means of the apparatus according to the first aspect is operated by the second judgment value calculating means.
With a simple configuration in which the second combustion state determination value calculated by the integration is compared with a second predetermined value to determine that an intermittent misfire has occurred in the cylinder, lean burn is performed. During operation, control based on the amount of change in the rotational angular acceleration of the internal combustion engine can be reliably performed in response to misfire, and control corresponding to deterioration in driving feeling due to intermittent misfire can be reliably performed. become.

[0229] Furthermore, in the apparatus according to claim 6 , when the combustion state determining means is configured to set the second predetermined value based on an operation state of the internal combustion engine (state 6). With the simple configuration, during lean burn operation, control based on the amount of change in the rotational angular acceleration of the internal combustion engine can be reliably performed in response to misfire, and the driving feeling caused by intermittent fire can be achieved. The control corresponding to the deterioration of the internal combustion engine is reliably performed in accordance with the operating state of the internal combustion engine.

[0230] In the apparatus according to the sixth aspect, when the combustion state determining means is configured to set the second predetermined value based on the rotation speed and the load of the internal combustion engine (aspect 7 ). With such a simple configuration, during lean burn operation, control based on the change in the rotational angular acceleration of the internal combustion engine can be reliably performed in response to misfire, and the driving feeling deteriorated due to intermittent fire can be reduced. Corresponding control is reliably performed in accordance with the rotational speed and load of the internal combustion engine.

[0231] According to the combustion state judging device of the internal combustion engine according to the seventh aspect, the combustion state judging means of the device according to the first aspect, wherein the combustion state judging means is integrated by the first judgment value calculating means. 1 Combustion state judgment value and 1st
It is determined that a continuous misfire has occurred in the cylinder by comparing the predetermined value with the predetermined value, and the second combustion state determination value and the second predetermined value calculated by the integration by the second determination value calculation means are calculated. With a simple configuration that is configured to determine that intermittent misfire has occurred in the cylinder in comparison, control based on the rotational angular acceleration of the internal combustion engine can be performed during lean burn operation. As a result, the control for avoiding the imbalance of the inter-cylinder output caused by the continuous misfire can be reliably performed, and the control based on the change in the rotational angular acceleration of the internal combustion engine can be reliably performed in response to the misfire. As a result, the control corresponding to the deterioration of the driving feeling caused by the intermittent misfire can be reliably performed.

Further, in the apparatus according to the seventh aspect , the combustion state determination means is configured to set the first predetermined value and the second predetermined value based on a rotation speed and a load of the internal combustion engine. In this case (aspect 8 ), with such a simple configuration, control based on the rotational angular acceleration of the internal combustion engine can be performed during lean burn operation, and imbalance in the inter-cylinder output due to continuous misfire is avoided. Control can be reliably performed in accordance with the rotational speed and load of the internal combustion engine, and control based on the change in the rotational angular acceleration of the internal combustion engine can be reliably performed in response to misfire. In addition to controlling the deterioration of the driving feeling caused by the intermittent fire, the control is reliably performed in accordance with the rotation speed and load of the internal combustion engine, and the statistical characteristics of the operating state of the engine are supported. There is an advantage that the combustion state can be controlled, and the lean limit operation can be reliably performed in a wider operation range.

[0233] Further, according to the combustion state control device for an internal combustion engine according to claim 8, first operating condition detecting the first operating condition parameter that varies due to the inter-cylinder torque difference of the internal combustion engine having a plurality of cylinders Detection means; first determination value calculation means for integrating the first operation state parameters detected by the first operation state detection means for each cylinder to calculate a first combustion state determination value for each cylinder; A second operating state detecting means for detecting a second operating state parameter that changes due to a torque change for each cylinder of the internal combustion engine; and a second operating state parameter detected by the second operating state detecting means. a second judgment value calculating means for calculating a second combustion state determination value for each cylinder by multiplying for each cylinder, the first combustion state determination value calculated by integrating the first judgment value calculating means and the second And determining the combustion state judging means the combustion state of the internal combustion engine based on both the second combustion state determination values <br/> calculated by integrating the determination value calculation means, based on the determination result of the combustion state determining means The following effects or advantages can be obtained with a simple configuration having a combustion state control means for controlling the combustion state.

[0234] (1) during lean burn operation, taking into account the probability and statistical properties of combustion variation, reliable combustion control, reliable combustion control for each cylinder which may correspond to a particular bi towards the continuous misfire and intermittent misfire Can be done. (2) It is possible to avoid imbalance in the inter-cylinder output caused by the continuous misfire, and to perform control corresponding to the deterioration of the driving feeling caused by the intermittent misfire.

Further, according to the combustion state control device for an internal combustion engine according to the ninth aspect, in the device according to the eighth aspect , the first operating state detecting means may include the first operating state parameter as the first operating state parameter. With a simple configuration that detects angular acceleration, it is possible to perform control based on the rotational angular acceleration of the internal combustion engine during lean burn operation, and to cancel the output between cylinders due to continuous misfire. Control to avoid balance can also be performed.

The apparatus according to claim 9 is provided with means for correcting the rotational angular acceleration of the internal combustion engine detected by the first operating state detecting means based on the load information of the internal combustion engine (aspect 9 ). Therefore, the calculation logic for calculating the first combustion state determination value is simplified. According to a combustion state control device for an internal combustion engine according to a tenth aspect of the present invention, in the device according to the eighth aspect , the second operating state detecting means may determine the rotational angular acceleration change of the internal combustion engine as the second operating state parameter. And detecting the amount of change in the rotational angular acceleration based on the deviation between the measured value of the rotational angular acceleration of the internal combustion engine and the smoothed value of the rotational angular acceleration detected so far. With this simple configuration, it is possible to perform control based on the amount of change in the rotational angular acceleration of the internal combustion engine during lean burn operation, and also to perform control that responds to the deterioration of driving feeling caused by intermittent fire. Become so.

Further, regarding the device according to claim 10 ,
When means for correcting the measured value of the rotational angular acceleration of the internal combustion engine with the load information of the internal combustion engine is provided (aspect 10 ), the calculation logic for calculating the second combustion state determination value is simplified. A combustion state control system for an internal combustion engine according to claim 11.
According to the control device, the device according to claim 10 is configured as described above.
The second determination value calculation means calculates the rotation angular acceleration change amount
Simple configuration that integrates only those with negative values
During lean burn operation, the rotational angular acceleration of the internal combustion engine changes.
Control based on the amount of gasification can be reliably performed in response to misfire
And the driving feeling is poor due to the intermittent fire.
The control corresponding to the change is surely performed.

(1) During lean-burn operation, reliable combustion control, especially for each cylinder capable of coping with both continuous and intermittent misfires, taking into account the probability and statistical properties of combustion fluctuations. Can do it. (2) It is possible to avoid imbalance in the inter-cylinder output caused by the continuous misfire, and to perform control corresponding to the deterioration of the driving feeling caused by the intermittent misfire.

[0239]

[0240]

[0241]

[0242]

[0243]

[Brief description of the drawings]

FIG. 1 is a control block diagram of a combustion state control device for an internal combustion engine as one embodiment of the present invention.

FIG. 2 is an overall configuration diagram of an engine system having a combustion state control device as one embodiment of the present invention.

FIG. 3 is a hardware block diagram showing a control system of an engine system having a combustion state control device as one embodiment of the present invention.

FIG. 4 is a flowchart illustrating an operation of the engine combustion state control device as one embodiment of the present invention.

FIG. 5 is a flowchart for explaining the operation of the engine combustion state control device as one embodiment of the present invention.

FIG. 6 is a flowchart for explaining the operation of the engine combustion state control device as one embodiment of the present invention.

FIG. 7 is a flowchart for explaining the operation of the engine combustion state control device as one embodiment of the present invention.

FIG. 8 is a flowchart for explaining the operation of the engine combustion state control device as one embodiment of the present invention.

FIG. 9 shows a combustion state of an engine as one embodiment of the present invention .
FIG. 4 is a waveform chart for explaining the operation of the control device.

FIG. 10 shows the combustion state of an engine as one embodiment of the present invention .
FIG. 5 is a waveform chart for explaining the operation of the state control device.

FIG. 11 shows a combustion state of an engine as one embodiment of the present invention .
6 is a correction characteristic map for explaining the operation of the state control device.
You.

FIG. 12 shows a combustion state of an engine as one embodiment of the present invention .
6 is a correction characteristic map for explaining the operation of the state control device.
You.

FIG. 13 shows the combustion state of an engine as one embodiment of the present invention .
5 is a schematic graph for explaining the operation of the state control device.
You.

FIG. 14 shows the combustion state of an engine as one embodiment of the present invention .
5 is a schematic graph for explaining the operation of the state control device.
You.

FIG. 15 shows the combustion state of an engine as one embodiment of the present invention .
Schematic perspective view showing a rotation fluctuation detection unit in the state control device
It is.

FIG. 16 shows the combustion state of an engine as one embodiment of the present invention .
5 is a schematic graph for explaining the operation of the state control device.
You.

FIG. 17 shows the combustion state of an engine as one embodiment of the present invention .
5 is a schematic graph for explaining the operation of the state control device.
You.

FIG. 18 shows the combustion state of an engine as one embodiment of the present invention .
5 is a schematic graph for explaining the operation of the state control device.
You.

FIG. 19 shows the combustion state of an engine as one embodiment of the present invention .
5 is a schematic graph for explaining the operation of the state control device.
You.

FIG. 20 shows the combustion state of an engine as one embodiment of the present invention .
5 is a schematic graph for explaining the operation of the state control device.
You.

FIG. 21 shows the combustion state of an engine as one embodiment of the present invention .
5 is a schematic graph for explaining the operation of the state control device.
You.

FIG. 22 shows the combustion state of an engine as one embodiment of the present invention .
5 is a schematic graph for explaining the operation of the state control device.
You.

FIG. 23 shows the combustion state of an engine as one embodiment of the present invention .
5 is a schematic graph for explaining the operation of the state control device.
You.

FIG. 24 shows torque fluctuation characteristics in a lean burn engine .
It is a graph which shows sex.

FIG. 25: Combustion fluctuation characteristics in a lean burn engine
FIG.

Continuation of the front page (56) References JP-A-4-109062 (JP, A) JP-A-5-52707 (JP, A) JP-A-7-83108 (JP, A) JP-A-4-311651 (JP) JP-A-2-64252 (JP, A) JP-A-4-81548 (JP, A) JP-A-5-340294 (JP, A) JP-A-8-28339 (JP, A) 2-103146 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/00-45/00 395

Claims (11)

(57) [Claims] 1. A first operating state detecting means for detecting a first operating state parameter that fluctuates due to an inter-cylinder torque difference of an internal combustion engine having a plurality of cylinders, and the first operating state detecting means detects the first operating state parameter. First determination value calculating means for integrating the first operating state parameter for each cylinder to calculate a first combustion state determination value for each cylinder; and changing the first combustion state parameter due to a torque variation for each cylinder of the internal combustion engine. Second operating state detecting means for detecting a second operating state parameter, and integrating the second operating state parameter detected by the second operating state detecting means for each cylinder to determine a second combustion state for each cylinder A second determination value calculating means for calculating a value; a first combustion state determination value calculated by integration by the first determination value calculating means; and a second determination value calculating means.
Combustion state determination means for determining the combustion state of the internal combustion engine based on both the second combustion state determination value calculated by the integration and the combustion state determination means. apparatus. 2. The internal combustion engine according to claim 1, wherein the first operating state detecting means is configured to detect a rotational angular acceleration of the internal combustion engine as the first operating state parameter. Combustion state determination device. 3. The system according to claim 1, wherein the second operating state detecting means is configured to detect a change in the rotational angular acceleration of the internal combustion engine as the second operating state parameter. A combustion state determination device for an internal combustion engine. 4. The method according to claim 1, wherein the second determination value calculating means includes: Only those with a negative value among the above rotation angular acceleration changes
4. The internal combustion engine according to claim 3, wherein
Combustion state determination device. 5. The combustion state determining means compares the first combustion state determination value calculated by integration by the first determination value calculation means with a first predetermined value, and a continuous misfire occurs in the cylinder. The apparatus for determining a combustion state of an internal combustion engine according to claim 1, wherein the apparatus is configured to determine that the combustion is in progress. 6. An intermittent misfire occurs in the cylinder by comparing the second combustion state determination value calculated by the integration by the second determination value calculation means with a second predetermined value. The apparatus for determining a combustion state of an internal combustion engine according to claim 1, wherein the apparatus is configured to determine that the combustion state has been performed. 7. The combustion state determination means compares the first combustion state determination value calculated by the integration by the first determination value calculation means with a first predetermined value to generate a continuous misfire in the cylinder. And the second combustion state determination value calculated by the integration by the second determination value calculation means is compared with a second predetermined value to determine that an intermittent misfire has occurred in the cylinder. The apparatus for determining a combustion state of an internal combustion engine according to claim 1, wherein the apparatus is configured to determine. 8. A first operating state detecting means for detecting a first operating state parameter which fluctuates due to an inter-cylinder torque difference of an internal combustion engine having a plurality of cylinders; First determination value calculating means for integrating the first operating state parameter for each cylinder to calculate a first combustion state determination value for each cylinder; and changing the first combustion state parameter due to a torque variation for each cylinder of the internal combustion engine. Second operating state detecting means for detecting a second operating state parameter, and integrating the second operating state parameter detected by the second operating state detecting means for each cylinder to determine a second combustion state for each cylinder A second determination value calculating means for calculating a value; a first combustion state determination value calculated by integration by the first determination value calculating means; and a second determination value calculating means.
Combustion state determination means for determining the combustion state of the internal combustion engine based on both the second combustion state determination value calculated by the integration, and controlling the combustion state based on the determination result of the combustion state determination means A combustion state control device for an internal combustion engine, comprising: 9. The internal combustion engine according to claim 8 , wherein said first operating state detecting means is configured to detect a rotational angular acceleration of said internal combustion engine as said first operating state parameter. Combustion state control device. 10. The second operating state detecting means is configured to detect a change amount of the rotational angular acceleration of the internal combustion engine as the second operating state parameter, and the measured value of the rotational angular acceleration of the internal combustion engine is provided. 9. The combustion state control device for an internal combustion engine according to claim 8, wherein the amount of change in the rotational angular acceleration is obtained based on a deviation between the detected rotational angular acceleration and a smoothed value. . 11. The second determination value calculating means, Only those with a negative value among the above rotation angular acceleration changes
The internal combustion engine according to claim 10, wherein
Seki's combustion state control device.