JP2003286890A - Controller for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely decide whether or not an engine is in a combustion stable state without fauty determination. <P>SOLUTION: A controller for the engine has a roughness control means 46 for setting a control value of an adjusting means having an injector 28 so that the combustion stability of the engine is maintained within a prescribed range. The controller includes an average deviation actually measuring means 46a for actually measuring the average deviation of the change of angular velocity for each of a plurality of control values set by a control value setting means 46d of the roughness control means under the same operating condition of the engine, a predicted value calculating means 46b for calculating the predicted value of the average deviation when the control value of the adjusting means is changed on the basis of the actually measured value of the average deviation obtained for each of the plurality of control values and a deciding means 46c for deciding whether or not the combustion state of the engine is proper on the basis of the difference between the predicted value of the average deviation and the actually measured value of the average deviation actually measured after the change of the control value. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device for controlling combustion stability of an engine so as to be maintained within a certain range based on fluctuations in angular velocity of engine rotation.

[0002]

2. Description of the Related Art Conventionally, as disclosed in, for example, Japanese Unexamined Patent Publication No. 9-264183, engine rotation between a predetermined crank angle within a range from a crank angle at which combustion is almost completed to a crank angle near the start of combustion of a next cylinder is known. The angular velocity fluctuation detecting means for detecting the angular velocity fluctuation, the discrimination means for discriminating the combustion state based on the fluctuation state of the angular velocity obtained based on the detection value of the angular velocity fluctuation detecting means, and the discrimination result of the combustion state by the discrimination means. An air-fuel ratio control unit that controls the air-fuel ratio of the engine by controlling the fuel injection amount according to the above is provided, and during lean combustion operation, combustion stability is achieved according to the combustion state determined based on the angular velocity of the engine rotation or its fluctuation. There is known an engine control device configured to control the air-fuel ratio near the lean limit while maintaining the property.

That is, the angular velocity of the engine rotation is sequentially detected based on the output signal of the crank angle sensor, and the deviation between the detected value of the angular velocity at the time of the current combustion and the detected value of the angular velocity at the time of the previous combustion in the same cylinder is determined. This deviation is determined by the first set value and the second set value which is lower than this by a predetermined amount.
The combustion state of the engine is determined by comparing with the set value, and when the deviation exceeds the first set value, the air-fuel ratio control amount is corrected in the rich direction to maintain combustion stability, and
When the deviation becomes smaller than the second set value, the air-fuel ratio control amount is corrected in the lean direction and the air-fuel ratio is controlled near the lean limit, thereby improving the fuel efficiency.

[0004]

As described above, the combustion state of the engine is determined on the basis of the deviation between the detected value of the angular velocity at the time of the current combustion and the detected value of the angular velocity at the time of the previous combustion. In this case, the engine is configured to have a uniform lean air-fuel ratio in the combustion chamber in an engine in which the fluctuation of engine rotation is relatively small in the combustion stable region, that is, in the region up to medium speed / medium load excluding the idle operation region. In the engine, whether the combustion state is near the lean limit can be determined to some extent accurately based on the deviation.

However, even when the engine is in the combustion stable region, the air-fuel ratio in the combustion chamber is significantly leaner than the stoichiometric air-fuel ratio in an engine in which the engine rotation is apt to significantly fluctuate, for example, in a low load / low rotation operating region. In the engine etc. which executes the control of the lean combustion mode in which the fuel is directly injected into the combustion chamber at a predetermined timing and the mixture is burned in a state where the air-fuel mixture is stratified around the spark plug,
Since it is necessary to set the judgment criteria in anticipation that the engine speed will change considerably in the stable combustion state, it is necessary to judge the suitability of the combustion state based on the deviation from the detected value of the angular velocity at the time of the previous combustion. However, there is a problem that it is apt to be erroneously determined that the combustion property of the engine is in a stable state even though the combustion stability is in a deteriorated state.

Further, in the engine that executes the control of the stratified lean combustion mode, the relationship between the variation rate of the target indicated mean effective pressure Pi representing the combustion state of the engine and the ignition timing is as shown in FIG. When the retard amount of is small, the fluctuation rate of the target indicated mean effective pressure Pi is small and the combustion state is relatively stable.
When the ignition timing retard amount reaches a certain value,
The fluctuation rate of the target indicated mean effective pressure Pi tends to increase rapidly.

Therefore, in an engine in which the engine rotation easily fluctuates remarkably when the engine is in the combustion stable region, it is possible to determine in advance that the combustion state tends to deteriorate by comparing the magnitudes of the angular velocity deviations. It is particularly difficult to determine the combustion state of the engine according to the magnitude of the deviation between the detected value of the angular velocity at the time of the current combustion and the detected value of the angular velocity at the time of the previous combustion, as described in the above publication. However, when the roughness control for sequentially retarding the ignition timing is executed, it is unavoidable that the ignition timing enters the misfire region and the combustion stability of the engine is impaired, as shown in FIG.

The present invention has been made in view of the above points, and provides an engine control device capable of accurately determining whether an engine is in a combustion stable state without causing an erroneous determination. The purpose is to do.

[0009]

The invention according to claim 1 is
Angular velocity fluctuation detecting means for detecting angular velocity fluctuation of engine rotation, adjusting means for adjusting the combustion state of the engine, and roughness control for setting the control value of the adjusting means so as to maintain the combustion stability of the engine within a certain range. In the engine control device having means, an average deviation measuring means for actually measuring an average deviation of the angular velocity fluctuations for each of a plurality of control values set by the roughness control means in the same operating state of the engine, and the adjusting means. Predicted value of the average deviation when the control value is changed, the predicted value calculation means for calculating based on the actual measurement value of the average deviation obtained for each of a plurality of control values, the predicted value of the average deviation, the control value The determination means determines whether or not the combustion state of the engine is appropriate based on the difference between the average deviation actually measured after the change of.

According to the above construction, even in an engine or the like in which the engine rotation is apt to significantly fluctuate when the engine is in the combustion stable region, the predicted value of the mean deviation and the mean deviation actually measured after the change of the control value are actually measured. Based on the difference from the value, it is possible to accurately determine whether or not the engine is in the combustion stable state without causing an erroneous determination.

According to a second aspect of the invention, the angular velocity fluctuation detecting means for detecting the angular velocity fluctuation of the engine rotation, the adjusting means for adjusting the combustion state of the engine, and the combustion stability of the engine are maintained within a certain range. In an engine control device having a roughness control means for setting a control value of the adjusting means, an average deviation of the angular velocity fluctuations is measured for each of a plurality of control values set by the roughness control means in the same operating state of the engine. Mean deviation measurement means to
The predicted value of the average deviation when the control value of the adjusting means is changed, the predicted value calculation means for calculating based on the actual measurement value of the average deviation obtained for each of the plurality of control values, and is predicted at the time of the previous control. Determination means for determining whether the difference between the predicted value of the average deviation and the measured value of the average deviation actually measured after the change of the control value is within an allowable range, and the predicted value of the average deviation and the measured value The roughness control means is provided with a control value setting means for setting the control value of the adjusting means in the direction of improving the combustion stability of the engine when it is determined that the difference is outside the allowable range. Is.

According to the above construction, the predicted value of the average deviation,
When it is determined that the engine is in a combustion stable state based on the difference between the average deviation actually measured after the change of the control value and the actually measured value, the adjustment means of the adjusting means is directed to improve the combustion stability of the engine. By setting the control value, it is possible to effectively prevent the combustion stability of the engine from deteriorating, even in an engine or the like in which the engine rotation tends to significantly change when the engine is in the combustion stable region.

According to a third aspect of the present invention, in the engine control apparatus according to the first or second aspect, the predicted value of the average deviation when the control value is changed is the most measured value by the average deviation measuring means. It is obtained by the least squares method based on a plurality of new measured values.

According to the above configuration, the predicted value of the average deviation when the control value of the adjusting means is changed can be easily and accurately obtained based on the measured value of the average deviation actually measured by the average deviation measuring means. It will be.

According to a fourth aspect of the present invention, in the engine control device according to the first or second aspect, the predicted value of the average deviation when the control value is changed is the most measured value by the average deviation measuring means. It is obtained by the successive approximation method based on a plurality of new measured values.

According to the above configuration, the predicted value of the average deviation when the control value of the adjusting means is changed can be accurately obtained based on the measured value of the average deviation actually measured by the average deviation measuring means. Become.

The invention according to claim 5 is the above-mentioned claims 2 to 4.
In the engine control device according to any one of items 1 to 3, the average deviation of the angular velocity fluctuations measured for each of the plurality of control values by the average deviation measuring means is divided into a plurality of regions according to the engine speed and the engine load. When the engine changes to a specific operating range, the stored value of the average deviation stored in the operating range is read out and used to control the adjusting means. The engine control device according to any one of claims 2 to 4.

According to the above configuration, fine engine roughness control corresponding to each operating region divided into a plurality of regions according to the engine speed and the engine load is executed, so that good combustion stability is achieved. It is possible to effectively improve the fuel efficiency while maintaining the above.

According to a sixth aspect of the present invention, in the engine control device according to the fifth aspect, there is a large amount of stored data of the average deviation, and there is a large amount of control value shift toward the combustion stability limit. Is reflected in the operating region where the stored data of the average deviation is small and is used for the control of the adjusting means.

According to the above construction, compared with the construction in which the roughness control is individually executed in each operation region divided into a plurality of regions according to the engine speed and the engine load, the adjusting means The optimum value can be quickly set as the control value.

The invention according to claim 7 is the above-mentioned claims 2 to 6.
In the engine control device according to any one of the above, when changing the control value of the adjusting means in the direction of the combustion stability limit, the number of times the actually measured value of the average deviation is determined to be outside the allowable range by the determining means. Is determined, and the larger the number of times is, the smaller the change amount of the control value is set.

According to the above construction, it is possible to quickly set the optimum value as the control value of the adjusting means while effectively preventing the deterioration of combustion stability due to the execution of the roughness control. .

The invention according to claim 8 is the above-mentioned claims 2 to 7.
In the engine control device according to any one of 1, the lean combustion mode in which the air-fuel ratio in the combustion chamber is made larger than the theoretical air-fuel ratio, and the rich combustion mode in which the air-fuel ratio is made smaller than the substantially theoretical air-fuel ratio or the theoretical air-fuel ratio, Air-fuel ratio control means for controlling to switch the combustion mode according to the operating state, and in the operating state of the lean combustion mode, based on the control value set by the roughness control means, at the time of transition to the rich combustion mode, And a target load setting means for setting a target load used for controlling the engine.

According to the above construction, it is possible to effectively prevent the occurrence of torque shock when the lean combustion mode is switched to the rich combustion mode.

According to a ninth aspect of the present invention, in the engine control device according to the eighth aspect, in the lean combustion mode operating condition, each operating region is divided into a plurality of regions according to the engine speed and the engine load. While setting the control value of each adjusting means for each, to obtain the average control value of the entire lean combustion mode based on these control values, the target load at the time of shifting to the rich combustion mode according to this average control value It is something to set.

According to the above construction, when the control value is changed due to the secular change of the engine, for example, the retard amount of the ignition timing is changed, it is used for controlling the engine based on the average control value of the entire lean combustion mode. The target load to be set is appropriately set.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic structure of an engine to which the present invention is applied.
It is a cycle gasoline engine, and includes an engine body 1 in which four cylinders are arranged in series, and an intake system and an exhaust system for the engine body 1. In each cylinder of the engine body 1, a combustion chamber 3 is formed above a piston 2, an intake port 4 and an exhaust port 5 are opened in the combustion chamber 3, and an intake valve 6 and an exhaust port are provided in these ports 4 and 5. A valve 7 is provided. A spark plug 8 is attached to the engine body 1 so as to face the combustion chamber 3. The spark plug 8 is connected to an ignition circuit 9 including an igniter capable of electronically controlling the ignition timing.

At the end of the crankshaft provided on the engine body 1, a plate for detection 11 having a protrusion 12 at a predetermined position on the outer periphery is attached, and a part corresponding to the outer periphery of the plate for detection 11 is attached. A crank angle sensor 13 including an electromagnetic pickup and the like is arranged in the. The crank angle sensor 13 outputs a pulse signal when the protrusion 12 passes through the crank angle sensor 13 during operation of the engine in which the plate 11 for detection rotates together with the crankshaft. The engine body 1 is also equipped with a water temperature sensor 14 that detects the temperature of the cooling water.

The intake system of the engine includes an intake passage 1 for introducing intake air introduced through an air cleaner 15 into the engine body 1.
6, the intake passage 16 has an upstream common intake passage 17, a surge tank 18 located downstream thereof, and a cylinder-specific intake passage 19 extending from the surge tank 18 to the intake port 4 of each cylinder. is doing. The common intake passage 17
Is provided with an air flow sensor 21 for detecting the amount of intake air and an electric throttle valve 22 for adjusting the amount of intake air, and I bypasses the electric throttle valve 22.
An SC passage 23 and an ISC valve 24 that opens and closes the passage 23 are provided. Further, in the intake passage 16, an intake temperature sensor 25 for detecting the temperature of intake air, a throttle valve 2
An idle switch 26 and the like for detecting the fully closed state of 2 are attached.

Further, an injector 28 for injecting and supplying the fuel is mounted on the upper peripheral portion of the combustion chamber 3. The injector 28 directly injects the fuel supplied through the fuel passage by a low-pressure and high-pressure fuel pump (not shown) into the combustion chamber 3, and operates in response to a signal (injection pulse) from the ECU 40 described later. However, the valve is opened at the injection timing set corresponding to the ignition timing for a time corresponding to the injection pulse width. During lean combustion mode operation, which will be described later, in the latter half of the compression stroke, fuel is injected in opposition to the tumble flow generated in the combustion chamber 3, and fuel mixture is made to collide with this tumble flow. Are retained around the ignition plug 8 in the state of being stratified at the ignition timing.

In order to form a tumble flow having a required strength in the combustion chamber 3 in the latter half of the compression stroke, the intake passage 19 for each cylinder is branched into two passages, which are located at the downstream ends of these passages. By opening the two intake ports 4 into the combustion chamber 3 and providing a pair of intake shutter valves 29 on the upstream side of the pair of passages, and closing the intake shutter valves 29 during lean combustion mode operation, the intake flow velocity is increased. Is accelerated to strengthen the tumble flow generated in the combustion chamber 3.

On the other hand, the exhaust system of the engine has an exhaust passage 31 communicating with the exhaust port 5 of each cylinder. The exhaust passage 31 is provided with a three-way catalyst on the upstream side and on the downstream side. A lean NOx catalyst (NOx catalyst that adsorbs or stores knocks to reduce them) that has a function of purifying NOx even in a lean state is provided.

Reference numeral 40 denotes a control unit (ECU) for controlling the engine, which is composed of a microcomputer or the like. The control unit 40 includes the crank angle sensor 13, water temperature sensor 14, air flow sensor 21, intake air temperature sensor 25, idle switch 26,
Each detection signal from the accelerator opening sensor or the like is input. Further, the ECU 40 outputs a signal for controlling the ignition timing to the ignition circuit 9 and a signal for controlling the fuel injection to the injector 28.

As shown in FIG. 2, the control unit 40 has a target load setting means 41 for setting a value corresponding to the target load of the engine, an operating area determining means 42 for determining the operating area of the engine, and the injector 28. The injection timing control means 43 for controlling the fuel injection timing by the engine, the ignition timing control means 44 for controlling the ignition timing of the air-fuel mixture by the spark plug 8, the angular velocity fluctuation detecting means 45 for detecting the angular velocity fluctuation of the engine rotation, Roughness control means 46 for correcting the control state of the adjusting means composed of the spark plug 8 and the injector 28 and executing the roughness control described later.
And an air-fuel ratio control means 47 for controlling the air-fuel ratio in the combustion chamber 3 according to the operating state of the engine.

The target load setting means 41 is, for example, as shown in FIG.
As shown in, a map preset according to the engine speed ne detected based on the output signal of the crank angle sensor 13 and the accelerator opening (accelerator operation amount) ac detected by the accelerator opening sensor 20 Volume efficiency setting means 41a for reading and setting virtual volume efficiency
And a filling efficiency calculating means 41b for calculating a virtual filling efficiency based on the volume efficiency and the atmospheric pressure at detected by an atmospheric pressure sensor (not shown), and a target indicated average corresponding to a target load based on the filling efficiency. Pi for calculating effective pressure
It has a calculation means 41c.

Further, the Pi calculating means 41c, when operating in a lean combustion mode described later, controls the control value of the adjusting means (i.e., the ignition timing of the ignition timing) in each operating region divided into a plurality of regions according to the engine speed and the engine load. Based on the retard amount), find the average control value in all regions of the lean combustion mode,
The target indicated mean effective pressure corresponding to the target load at the time of shifting from the lean combustion mode to the rich combustion mode is set according to the average control value. That is, during the operation in the lean combustion mode, the increase amount of the engine torque due to the correction for retarding the ignition timing in the roughness control means 46 is calculated based on the average control value, and the target indicated mean effective pressure of the engine is calculated. By correcting the control map for setting the (target load) according to the increase amount of the engine torque, it is possible to prevent torque shock from occurring when the lean combustion mode is switched to the rich combustion mode. .

The operating area discriminating means 42 discriminates the operating area based on the target indicated mean effective pressure corresponding to the target load set by the target load setting means 41 and the detected value of the engine speed, and the operating area is determined. The combustion mode of the engine is set according to the region. That is, in the operating region in which the target load and the engine speed are equal to or lower than a predetermined value, for example, in the low-load / low-rotation operating region surrounded by a thick line, the lean combustion mode is set and the other operating conditions are set. In the region, the rich combustion mode is set. Further, the operating region of the lean combustion mode is divided into a plurality of regions according to the target load and the engine speed, respectively, as shown by the broken line in the figure, and the first region (1) to Twelfth area (12)
In the idle rotation region (I), the roughness control by the roughness control means 46 is executed.

The injection timing control means 43 sets the basic injection timing at a predetermined timing of the intake stroke in the rich combustion mode operation area in accordance with the operation area determined by the operation area determination means 42, and lean combustion is performed. In the operation region of the mode, the basic injection timing is set at a predetermined timing of the compression stroke, and the basic injection timing is corrected if necessary. Specifically, in the lean combustion mode operation region, the basic injection timing is set at a timing earlier than the ignition timing set by the ignition timing setting means 44 by a predetermined timing.

Further, the ignition timing control means 44, for each operating region determined by the operating region determining means 42, the target load of the engine set by the target load setting means 41 and the detected value of the engine speed. The basic ignition timing of the air-fuel mixture is read and set from a map preset according to the above, and in the operating region of the lean combustion mode, as will be described later, a control value (ignition timing of the ignition timing set by the roughness control means 46 is set. It is configured to correct the ignition timing based on the retard amount).

The angular velocity fluctuation detecting means 45 detects the angular velocity of the engine rotation from the interval of the output time based on the signal from the crank angle sensor 13, and based on the detected value of this angular velocity, the previous value of the same cylinder. It is configured to detect the difference between the angular velocity during combustion and the angular velocity during the current combustion. The detection of the angular velocity is performed, for example, in a predetermined crank angle section within a range from a crank angle at which combustion is almost completed to a crank angle near the combustion start timing of the next cylinder (preferably in the middle of the expansion stroke).

In a preferred embodiment, the AT of the expansion stroke
The crank angle detection point by the crank angle sensor 13 and the like are set so that the angular velocity detection is performed in the section of DC 85 ° to 130 ° CA. For example, as shown in FIG. 5, ATDC 85 ° CA and ATDC 130 ° C of each cylinder
The projection 12 of the plate 11 to be detected so that A and A are detected.
And the arrangement of the crank angle sensor 13 are set,
The angular velocity is obtained in the section of 45 ° CA between these detection points. ATDC means after top dead center, and CA means crank angle.

FIG. 6 shows torque and angular velocity (rad / se) in an in-line 4-cylinder 4-cycle gasoline engine.
The change in c) is shown with the horizontal axis as the crank angle. As shown in this figure, combustion is performed in the order of the fourth cylinder, the second cylinder, the first cylinder, and the third cylinder, the gas pressure torque (two-dot chain line) is changed by the combustion, and the inertia is caused by the movement of the piston. The torque changes and the combined torque of the gas pressure torque and the inertia torque when combustion is normally performed in each cylinder is indicated by a thick solid line. Then, the angular velocity changes according to the difference between the combined torque and the torque required to maintain the angular velocity, and during normal combustion, the change in the angular velocity becomes as shown by the solid line A. On the other hand, when misfire occurs in the first cylinder, the amount of torque increase due to combustion in the first cylinder decreases, and the change in angular velocity is as indicated by broken line B.

That is, during normal combustion of the engine, the angular velocity increases as the combustion pressure increases after ignition, and decreases as the combustion ends. On the other hand, at the time of misfire, the increase in the angular velocity during the combustion process is small, but at the beginning of the combustion process, the angular velocity is relatively low even during normal combustion, so the difference from normal combustion is small, and the combustion pressure increases from about the middle of the stroke. The decrease in the angular velocity due to the decrease becomes remarkable, and the difference from the normal combustion increases.
In the cylinder next to the misfiring cylinder (for example, the third cylinder when the first cylinder misfires), the influence of the misfire of the previous cylinder remains and the angular velocity is at a low level in the first half of the expansion stroke. As it decreases, the torque required to maintain the angular velocity also decreases, and the angular acceleration increases under the same torque.
As the process progresses, the angular velocity under normal conditions gradually approaches.

FIG. 7 shows the correlation between combustion pressure and angular velocity fluctuation. The horizontal axis represents the crank angle with the compression top dead center of one cylinder being 0 ° CA, and the vertical axis is the vertical axis. It represents the correlation coefficient. Here, the correlation coefficient indicates the degree of influence of the combustion state (combustion pressure) of the cylinder on the angular velocity, and if this value is positive, fluctuations in the combustion pressure of the cylinder (combustion due to misfire). Pressure drop) and the angular velocity fluctuation (angular velocity fluctuation) are highly correlated, and if this value is negative, it means that the combustion pressure fluctuation of the preceding cylinder has a greater effect on the angular speed fluctuation than the cylinder concerned. means.

As is apparent from FIGS. 6 and 7, a main combustion period (about TDC to ATDC 20 ° CA) after ignition and a delay period (about 20 ° CA) until the torque increase due to combustion is reflected in the angular velocity. Until the time elapses, the combustion state of the previous cylinder has a greater effect on the angular velocity fluctuation, and the period from the time when these periods have elapsed (corresponding to the time when the combustion is almost completed) to the vicinity of the combustion start time of the next cylinder , Correlation is obtained between the fluctuation of the combustion pressure of the cylinder and the fluctuation of the angular velocity.
Therefore, the crank angle (ATDC4
0 ° CA) to the crank angle (ATDC 200 ° CA) around the combustion start timing of the next cylinder, and detects the angular velocity, and the variation (the angular velocity during the previous combustion and the angular velocity during the current combustion) Deviation of),
It is possible to determine the combustion state with sufficient accuracy.

Further, the angular velocity fluctuation detecting means 45 is adapted to obtain the angular velocity fluctuation from the angular velocity data (angular velocity fluctuation detection data). Here, in order to remove an element that becomes noise for the determination of the combustion state by the angular velocity fluctuation detecting means 45, when the angular velocity fluctuation is obtained from the angular velocity data, the frequency component of an integer multiple of 0.5 of the engine rotation and the engine Processing for removing frequency components lower than the 0.5th order of rotation is performed.

That is, as a noise-like element that causes angular velocity fluctuations other than fluctuations in combustion state, angular velocity fluctuations due to the effect of resonance with an explosion as a vibration source, and wheel rotations due to wheel and drive system imbalance There are fluctuations in angular velocity that occur, fluctuations in angular velocity due to the influence of vibration that acts on the tire from the road surface, and the like. Then, as shown in FIG. 8, the noise of the explosion rotation order component due to the influence of the resonance occurs at a frequency of 0.5 order of the engine rotation and an integral multiple thereof, and the noise due to the wheel rotation due to the imbalance. The noise caused by the influence of the road surface and the road surface occurs in a low frequency range lower than the 0.5th order of engine rotation.

Therefore, the angular velocity fluctuation detecting means 45 first carries out a process for removing the signals of the 0.5th order of the engine rotation and the integral multiples thereof from the detected data of the angular velocity. Specifically, the angular velocity difference between the current value and the value in the previous cycle of the same cylinder is obtained, that is, in a 4-cylinder engine, the current angular velocity detection value ω [i] and the fourth previous angular velocity detection value ω [i-4 ] Difference with
By obtaining ω, as shown in FIG. 9, angular velocity fluctuation data excluding the frequency components of the 0.5th order of engine rotation and integer multiples thereof can be obtained.

Further, the angular velocity fluctuation detecting means 45 carries out noise processing for removing frequency components lower than the 0.5th order of engine rotation. Specifically, as shown in FIG. 10, the frequency range components lower than the 0.5th order are reduced by the arithmetic processing as a high-pass filter (for example, a FIR-type rotation synchronization digital filter).
By such noise processing, the frequency components of the 0.5th order and integer multiples thereof and the frequency range components lower than the 0.5th order are removed, and the data showing the angular velocity fluctuation according to the fluctuation of the combustion state is accurately obtained. Will be required.

The roughness control means 46 is the same as that shown in FIG.
As shown in FIG. 1, the average deviation measuring means 46a for actually measuring the average deviation of the angular velocity fluctuations based on the angular velocity fluctuation data detected by the angular velocity fluctuation detecting means 45, and the control value of the adjusting means composed of the ignition plug 8 (ignition Prediction value calculating means 46b for calculating the predicted value of the average deviation when the retard amount of the timing) is changed, and the determination of whether the combustion state of the engine is appropriate based on the measured value and the predicted value of the average deviation. Means 46c and control value setting means 46d for setting a control value corresponding to the judgment result of this judgment means 46c
And a storage unit 46 for storing the control value set by the control value setting unit 46d, the measured value of the average deviation actually measured by the average deviation measuring unit 46a, and the like.
e and.

In the lean combustion mode operation state, the average deviation measuring means 46a is used when the engine is in the same operation state, that is, in the first region (1) to the first region shown in FIG.
During steady operation such as when one of the two regions (12) continues for a predetermined time, the engine speed at the previous combustion and the engine speed at this time detected by the angular velocity fluctuation detecting means 45. After the data of about 200 cycles are collected by calculating the angular velocity difference between the above and the angular velocity for about 4 seconds, an average deviation is obtained based on the average value and the angular velocity difference, and the average deviation is determined by the determining means 46c.
And is stored in the storage means 46e.

The predicted value calculation means 46b calculates the predicted value of the average deviation that changes due to the correction of the ignition timing based on the control value set by the control value setting means 46d, and the average deviation measuring means 46a. It is obtained by the least-squares method based on the latest measured values obtained in the above. For example, the control value setting means 46
When the correction for changing the ignition timing in the direction of sequentially retarding is executed by d, the storage means 46e is used.
The four types of average deviations (each measured value of the average deviations calculated and stored each time the retard control of the ignition timing is executed) stored in are read out, and the ignition timing is further calculated based on these values. How the average deviation changes when retarded is calculated by the least squares method in the predicted value calculation means 46b.

Immediately after the engine is started and the actual measurement data of the average deviation measuring means 46b does not exist, the least squares method is used based on the dummy data (standard data set in advance) stored in the storage means 46e. It is configured to calculate the predicted value of the average deviation. In addition, if there is no actual measurement data for the relevant operating area at this time, or if there is insufficient actual measurement data, but there are many actual measurement data in other operating areas, this actual measurement data is The actual measurement data of the existing operating region is read out, and the data is processed so as to be adapted to the fluctuation state of the actual measurement data stored in the operating region at the present time, whereby it is used for the roughness control.

The determining means 46c is the predictive value calculating means 4 during the previous control in the lean combustion mode operation state.
The predicted value of the average deviation calculated in 6b and the measured value of the average deviation actually obtained by the average deviation measuring means 46a when the control value setting means 46d executes the control for changing the control value. The suitability of the combustion state of the engine is determined based on the difference between

That is, when executing the control for sequentially retarding the ignition timing or advancing the ignition timing, the prediction of the average deviation obtained during the previous control (before the retard or advance of the ignition timing is performed) is performed. The determination means determines whether or not the difference between the value and the actual measurement value of the average deviation obtained during the current control (after the ignition timing is retarded or advanced) is within a preset allowable range. It is determined at 46c. Then, the determination means 4
In 6c, when it is confirmed that the difference between the predicted value of the average deviation and the actual measured value of the average deviation is within the allowable range, it is determined that the combustion state of the engine is appropriate, and this determination is made. When a signal is output to the control value setting means 46d and it is confirmed that the difference is out of the allowable range, it is determined that the combustion state of the engine is inappropriate, and this determination signal is used as the control value setting means. It is configured to output to 46d.

The control value setting means 46d is the judging means 4
When it is determined in 6c that the difference between the predicted value of the average deviation and the actual measurement value is outside the allowable range, the ignition timing is retarded to improve the combustion stability of the engine, that is, the ignition timing is set. It is configured to set a control value to be corrected in the advance direction. On the other hand, when it is confirmed by the determination means 46c that the difference between the predicted value of the average deviation and the measured value is within the allowable range, or when the control is started immediately after the engine is started, the ignition timing is retarded. Control value (amount of ignition retard) to correct the fuel consumption of the engine
Is set by the control value setting means 46d, and this control value is output to the ignition timing control means 44.

Further, in the lean combustion mode operation state, the control value for correcting the fuel injection timing is calculated based on the control value (retard amount of the ignition timing) set by the control value setting means 46d. As a result, the fuel is injected at a timing earlier than the ignition timing by a predetermined timing. That is, as shown in FIG. 12, the combustion stable region in the lean combustion mode operating state in which the air-fuel mixture is burned in the state of being stratified around the spark plug tends to narrow as the ignition timing is retarded, as shown in FIG. When the ignition timing is retarded, there is a certain correspondence between the combustion stable region and the time of fuel injection.
Therefore, by setting the retard amount of the ignition timing to a predetermined value, the fuel injection timing capable of maintaining the combustion stability is automatically obtained.

The air-fuel ratio control means 47 shown in FIG. 2 outputs the output of the air flow sensor 21, the output of the water temperature sensor 14, etc., and the target indicated mean effective pressure corresponding to the target load set by the target load setting means 41, The air-fuel ratio is controlled by controlling the fuel injection amount from the injector 28 and the opening degree of the electric throttle valve 22 based on the detected value of the engine load and the operating range determined by the operating range determining means 42. To do. That is, the air-fuel ratio is set to a predetermined lean air-fuel ratio in the operating region of the lean combustion mode up to the medium speed / medium load shown in FIG. 4 in the warm state of the engine, and the air-fuel ratio is increased in the rich combustion mode of high speed / high load. The air-fuel ratio control means 47 is configured to execute control for switching the combustion mode according to the operating state of the engine so as to make the air-fuel ratio substantially lower than or equal to the theoretical air-fuel ratio.

Further, when controlling the lean combustion mode,
According to the control value of the spark plug 8 set in the roughness control means 46, that is, the retard amount of the ignition timing, the target indicated mean effective pressure corresponding to the target load at the time of shifting to the rich combustion mode is the target load setting means. The air-fuel ratio at the time of switching the combustion mode is set by the air-fuel ratio control means 47 based on the target indicated mean effective pressure.

Next, the operation of the apparatus of this embodiment will be described with reference to the flowcharts shown in FIGS.
FIG. 13 shows the main control operation for setting the fuel injection timing and the air-fuel mixture ignition timing. When this control operation starts, first, in the target load setting means 41, the volumetric efficiency of intake air corresponding to the engine speed and the accelerator opening is read out from the map and set (step S1), and the calculated value of this volumetric efficiency is set. After calculating the charging efficiency of the intake air based on the atmospheric pressure (step S
2) Based on the charging efficiency, the target indicated mean effective pressure Pi corresponding to the target load of the engine is calculated (step S3).

Next, the operating state determination means 42 determines whether the current operating state is the lean combustion mode (step S4), and when it is determined NO and it is confirmed that the rich combustion mode is in effect. Sets the ignition timing IG of the air-fuel mixture according to the basic ignition timing read from the map based on the target indicated mean effective pressure Pi (step S5), and at the same time, sets the target indicated mean effective pressure Pi.
The fuel injection timing INJ is set according to the basic injection timing read from the map based on the
6).

When it is determined YES in step S4 and it is confirmed that the current operating state is the lean combustion mode, the roughness control means 46 executes the correction for retarding the ignition timing in the past. It is determined whether or not it is in the open state (step S7). If YES is determined in this step S7 and it is confirmed that the roughness control data already exists, the roughness control described later is executed (step S8).

On the other hand, when it is confirmed that the roughness control data does not exist because it is determined to be NO in the above step S7 and the vehicle is in the state immediately after the start of the start, the map based on the target indicated mean effective pressure Pi is used. After the ignition timing IG of the air-fuel mixture is set according to the read basic ignition timing (step S9), the process proceeds to step S9 and the roughness control is executed. After that, the control signal of the ignition timing and the control signal of the injection timing corresponding to the ignition timing IG set in the roughness control or steps S5, 6 and the like are output to each actuator (step S1).
0, S11).

Next, the main routine of the roughness control executed in step S8 will be described with reference to the flowchart shown in FIG. When the control operation is started, first, the data of the engine speed ne and the target indicated mean effective pressure Pi are acquired (step S2).
1), based on this data, the first region to 12 shown in FIG.
After the area corresponding to the current operation area is read out (step S22), complementary control of control data described later is executed (step S23).

Then, it is determined whether or not the operating region of the engine has changed between the previous control and the current control (step S24), and if NO is determined, the engine is maintained in the same operating region. If it is confirmed that
It is determined whether or not the timer for measuring the elapse of the sampling time set in advance to about 4 seconds has expired (step S25). And this step S2
When it is determined to be YES in 5 and it is confirmed that the timer has timed out, after executing the ignition timing and injection timing setting control described later (step S26), the count value of the timer is reset to 0. (Step S27) and the process returns.

When it is determined NO in step S25 and it is confirmed that the timer has not timed up yet, the count value of the timer is incremented (step S28) and the process returns. If it is determined YES in step S24 and it is confirmed that the operating region has changed before the timer times out, the control data of the transition destination region stored in the storage means 46e, that is, the ignition is performed. After reading the control value composed of the retard amount of the time and the actual measurement value of the average deviation (step S28), the process proceeds to step S27 and the count value of the timer is reset.

Next, the complementary control operation of the control data executed in step S23 will be described with reference to the flow chart shown in FIG. When the above control operation starts, first, based on the control data stored in each region of the lean combustion mode divided into a plurality of regions, the average retard amount (average control value) of the ignition timing in all regions of the lean combustion mode is calculated. While calculating (step S3
1), the target indicated mean effective pressure Pi based on the calculated value
Is calculated (step S32).

After that, when shifting from the lean combustion mode to the rich combustion mode, a control map for setting a target load (target indicated mean effective pressure) used for controlling the engine is set to the ignition timing retard control. The correction is performed based on the corresponding increase in the target indicated mean effective pressure Pi (step S33), and the region in which the ignition timing is most retarded and the maximum retard amount Rmax in each region of the lean combustion mode are set. Read (step S3
4).

Then, it is judged whether or not the roughness control is already executed in the current area (step S3).
5) If YES is determined, the retard amount Rα of the ignition timing in the current region is the maximum retard amount R
It is determined whether it is less than 1/2 of max (step S36). If NO is determined in this step S36 and it is confirmed that a predetermined number of control data are accumulated in the current area, the flow returns as it is, and the accumulated control data is Used for setting control of ignition timing and injection timing.

On the other hand, when it is judged NO in step S35 and it is confirmed that the roughness control is not already executed in the current region, or Y in step S36.
When it is determined to be ES and it is confirmed that the retard amount Rα of the ignition timing in the current region is less than 1/2 of the maximum retard amount Rmax, the above step S34
The control data in the current region is complemented based on the maximum retard amount Rmax in the region read out in step 1, that is, the region in which the ignition timing is most retarded (step S3).
8). Specifically, when the number of times the roughness control is executed in the current region is small, the maximum retard amount Rma is set.
Based on x, while setting the control value (retard amount of the ignition timing) of the current region, the data obtained by processing the measured value of the average deviation obtained in the region where the ignition timing is most retarded, The actual deviation of the average deviation in the current area is stored in the storage means 46e.

Next, the ignition timing and injection timing setting control operation executed in step S26 in the main control operation of the roughness control will be described based on the flowchart shown in FIG. When the above control operation starts,
First, a control value for improving combustion stability is set according to the number Ad of executions of advance control measured by a counter (not shown) in the current region, that is, the determination result of the determination unit 46c as described later. The number of times is determined (step S41).

When it is confirmed by the determination in step S41 that the number of executions of advance control is 0 or relatively small, the retard width of the ignition timing to be changed at the time of this control is compared with the time at the time of the previous control. Value αn is 1 °
(Step S42), and when it is confirmed that the number of executions of the advance control is medium, the expected value αn of the retard width is set to 0.5 ° (step S43). In addition, as a result of the determination, when it is confirmed that the advance control is executed many times, the expected value αn of the retard width is set to 0.25 ° (step S
44).

Next, the actual measurement value of the average deviation σ acquired in the actual measurement control of the average deviation described below is read (step S45), and the predicted value of the average deviation σ calculated in the previous control operation and the average deviation σ are also read. After calculating the difference β from the actual measurement value of (step S46), it is determined whether or not the absolute value of the difference β is within a preset allowable range (step S47).

When it is determined YES in step S47 and it is confirmed that the difference β is within the allowable range, the retard width is set according to the preset value αn of the retard width set in any of steps S41 to S43. The predicted value of the average deviation σ when executing the ignition timing control based on the retard width α of the ignition timing is set while the retard width α of the ignition timing used in the current control is set (step S48). Mean deviation σ stored in 46e
Based on the actual measured value, that is, the four latest measured values actually acquired in the actual measurement control of the average deviation σ, or the processing data obtained in step S37 of the complementary control of the control data shown in FIG. It is calculated by multiplication (step S49).

Immediately after the start of the engine where the measured data of the mean deviation measuring means 46b does not exist, the mean deviation σ of the mean deviation σ is calculated by the least square method based on the four dummy data stored in the storing means 46e. Calculate the predicted value. The dummy data is obtained by advancing by 4 ° from the initial time (basic ignition timing) set to a value that does not impair the combustion stability,
This is standard data set in advance as a value corresponding to the actual measurement value of the average deviation σ when the ignition timing is retarded by 1 °.

If it is determined NO in step S47 and it is confirmed that the difference β between the predicted value of the average deviation σ and the measured value of the average deviation σ is outside the allowable range, the next control is performed. The retard width α of the ignition timing at the time is set to -1 ° (step S50), and the measured value of the counter for measuring the number Ad of executions of the advance control is incremented by 1 (step S51), and then the process proceeds to step S49. Then, the predicted value of the average deviation σ when the ignition timing is advanced is stored in the storage means 46.
It is calculated by the least squares method based on the measured value of the average deviation σ stored in e (step S51).

Then, by updating the ignition timing IG (IG = IG-α) based on the retard width α set in step S48 or step S50, the final retard amount (adjusting means) with respect to the basic ignition timing is adjusted. Control value) (step S52), and the injection timing INJ is updated (INJ = IN based on the retard width α).
J-α) is performed (step S52) so that the injection timing INJ is advanced at a timing earlier than the ignition timing IG by a predetermined time.
To set.

Next, the measurement control operation of the average deviation σ
This will be described based on the flowchart shown in FIG. The actual measurement control operation of the average deviation σ is executed in a routine different from the above-mentioned roughness control. When the actual measurement control operation of the average deviation σ starts, the angular velocity fluctuation detecting means 45 first detects angular velocity fluctuation data (step S61), and after performing noise processing for removing noise elements from the fluctuation data ( Step S62),
The fluctuation data after the noise processing is stored and stored in the storage means 46e (step S63).

Then, it is determined whether or not the timer for detecting that a predetermined number of fluctuation data has been obtained has timed out (step S64), and when YES is determined, the average deviation measuring means 46a is used. , After calculating the average deviation σ of the angular velocity fluctuation based on the following equation (step S6
5) Return.

Σ = Σ | dω [j] −dωf | / N (j = 1 to N) In the above equation, dω [j] is the deviation data after the noise processing measured within a predetermined sampling time, and dωf
Indicates the average value of the above-mentioned fluctuation data, and N indicates the number of times of measurement of the deviation data.

As described above, the angular velocity fluctuation detecting means 45 for detecting the angular velocity fluctuation of the engine rotation, the adjusting means including the injector 28 for adjusting the combustion state of the engine, and the combustion stability of the engine are maintained within a certain range. In an engine control device having a roughness control means 46 for setting the control value of the adjusting means (retard amount of ignition timing), and an actual measurement value of the average deviation σ of the angular velocity fluctuation measured by the average deviation measuring means 46a, Prediction value calculation means 46b
Based on the difference from the predicted value of the average deviation σ obtained by
Determining means 46c for determining whether the engine is in a stable combustion state
In the engine operating range where the engine rotation is apt to change significantly, for example, in a low load / low rotation operating range, the air-fuel ratio in the combustion chamber is set significantly leaner than the theoretical air-fuel ratio, and Even in an engine or the like configured to execute a lean combustion mode control in which fuel is directly injected into the combustion chamber 3 at a timing to burn the air-fuel mixture around the ignition plug in a stratified state, the engine has stable combustion. Whether or not there is a state can be accurately determined without causing an erroneous determination.

FIG. 17 shows how the above-mentioned average deviation σ is when the roughness control for gradually retarding the ignition timing is executed from the initial time set at the time when the combustion stability is not impaired in the above engine. The solid line shows the change state of the actual measurement value, and the broken line shows the change state of the predicted value. From this verification data, the measured value of the average deviation σ fluctuates (increases or decreases) as the retard amount of the ignition timing increases even in the combustion stable region, and the retard amount of the ignition timing becomes a predetermined value or more and a misfire occurs. It can be seen that as the measured value approaches the range, the above-mentioned variation of the actual measurement value becomes remarkable and the difference between the actual measurement value and the predicted value of the average deviation σ tends to increase. Therefore, the determination means 46c determines whether or not the difference between the measured value and the predicted value of the average deviation σ is within a preset allowable range k centered on the predicted value, whereby the ignition timing is misfired. It is possible to determine whether or not the area is approached.

When the discriminating means 46c determines that the difference between the predicted value of the average deviation σ and the actually measured value is outside the allowable range k, the combustion stability of the engine is improved. By setting the control value composed of the retard amount of the ignition timing and correcting the fuel injection timing corresponding to this, it is possible to reliably prevent the ignition timing from entering the misfire region as shown in FIG. Thus, while maintaining the combustion stability in a good state, it is possible to retard the ignition timing within the combustion stability limit as much as possible to improve fuel efficiency.

Further, as shown in the above-mentioned embodiment, the predicted value of the average deviation σ when the control value consisting of the retard amount of the ignition timing is changed is the plurality of the latest measured values measured by the average deviation measuring means 46b. If the least squares method is used to obtain the predicted value of the average deviation, it is possible to easily and accurately obtain the predicted value.

Instead of the above-mentioned embodiment, the above-mentioned method is performed by the successive approximation method or another method such as the successive acceleration relaxation method or the steepest descent method based on the latest measured values measured by the average deviation measuring means 46b. Mean deviation σ
You may make it calculate the predicted value of. In particular, the successive approximation method has an advantage that the predicted value of the average deviation σ can be calculated with high accuracy.

Further, as shown in the above embodiment, the average deviation σ of the angular velocity fluctuation measured by the average deviation measuring means 46a for each of a plurality of control values is set in a plurality of regions according to the engine speed and the engine load. When the engine changes to a specific operation range, the stored value of the average deviation σ stored in the operation range is read out from the storage means 46e and stored in the storage means 46e. According to the configuration that is used for controlling the adjusting means including the injector 28, it is possible to execute fine engine roughness control corresponding to the above-mentioned region, so that the combustion stability of the engine is maintained in a good state. There is an advantage that the fuel consumption can be effectively improved.

In particular, as shown in the above-mentioned embodiment, the data of the operating range in which there is a large amount of stored data of the average deviation σ and a large amount of shift of the control value in the direction of the combustion stability limit (retard direction) is used as the average deviation. When configured to be used for controlling the adjusting means including the injector 28 by reflecting the stored data in the operating region, the control for gradually retarding the ignition timing from the initial time in each region is executed. The optimum value of the ignition timing can be quickly obtained as compared with the case of being configured.

Further, in the above embodiment, when the control value of the adjusting means is changed in the direction of the combustion stability limit (direction of retarding the ignition timing), the actually measured value of the average deviation σ by the judging means 46c is within the allowable range. It is configured to determine the number of times it is determined to be out of k, and to set the variation amount of the control value, that is, the retard width of the ignition timing to a smaller value as the number of times is greater, so that the roughness control is executed. There is an advantage that the optimum value of the ignition timing can be obtained more quickly while effectively preventing the deterioration of combustion stability due to.

For example, if there is a specific region where combustion stability is likely to deteriorate in response to retard control of the ignition timing for some reason, if the ignition timing is greatly retarded in this region, engine misfire or the like may occur. Since it is likely to occur, it is possible to prevent the combustion stability of the engine from deteriorating by setting the change amount of the control value in the specific region to a small value. On the other hand, in a region other than the specific region, the ignition timing can be quickly retarded to the optimum value by setting the change amount of the control value to a large value.

Further, as described above, the engine is operated in the lean combustion mode in which the air-fuel ratio in the combustion chamber 4 is made larger than the stoichiometric air-fuel ratio and in the rich combustion mode in which the air-fuel ratio is made to be substantially stoichiometric or smaller than the stoichiometric air-fuel ratio. In an engine provided with an air-fuel ratio control means for controlling the combustion mode to be switched according to the state, the control value (retard amount of ignition timing) set by the roughness control means 46 in the operating state of the lean combustion mode. Based on the above, when shifting to the rich combustion mode, the target load setting means 41 for setting the target load (target indicated mean effective pressure) used for controlling the engine.
Since the above is provided, there is an advantage that torque shock can be prevented from occurring when the combustion mode is changed.

That is, the target load setting means 41 calculates the amount of increase in the engine torque for executing the control for retarding the ignition timing to the optimum position by the roughness control means 46, based on the control value. By correcting the control map for setting the target indicated mean effective pressure (target load) according to the increase amount of the engine torque, it is effective to generate a torque shock when switching from the lean combustion mode to the rich combustion mode. Can be prevented.

Particularly, in the above embodiment, in the lean combustion mode operation state, the control values of the adjusting means are set in each operation area divided into a plurality of areas in accordance with the engine speed and the engine load, and these controls are performed. The average control value of the entire lean combustion mode is calculated based on the value, and the target load at the time of shifting to the rich combustion mode is set according to this average control value, so that the target load is divided into a plurality of regions as described above. In addition, even if any region of the lean combustion mode is changed to the rich combustion mode, there is an advantage that the torque shock can be easily and effectively prevented at the time of switching. Moreover, when the engine changes over time, the average control value for the entire lean combustion mode changes, so by setting the target load based on this average control value, the engine changes over time. There is an advantage that the air-fuel ratio control corresponding to the above can be executed.

The engine control device according to the present invention is not limited to the above embodiment, and various modifications can be made. For example, the angular velocity fluctuation detecting means 45 may detect an angular velocity equivalent amount such as a rotation cycle instead of the angular velocity. Further, as the control value of the adjusting means for adjusting the combustion stability of the engine so as to maintain it within a certain range, it is conceivable to use the air-fuel ratio in the combustion chamber instead of the ignition timing and the injection timing.

Further, in the specific example of the roughness control in the above-described embodiment, when the angular velocity fluctuation is obtained based on the angular velocity data, the process of removing the 0.5th order of the engine rotation and the component of its integral multiple and the 0.5th order. Although the process of removing low frequency components is always performed, the effect of resonance caused by explosion vibration becomes large on the high speed side of the engine. It may be performed only in the high-speed area.

[0095]

As described above, according to the present invention, the angular velocity fluctuation detecting means for detecting the angular velocity fluctuation of the engine rotation, the adjusting means for adjusting the combustion state of the engine, and the combustion stability of the engine are maintained within a certain range. In the engine control device having the roughness control means for setting the control value of the adjusting means, the average deviation of the angular velocity fluctuations for each of the plurality of control values set by the roughness control means in the same operating state of the engine. Prediction value calculation for calculating the average deviation measurement means for actually measuring the average deviation and the predicted value of the average deviation when the control value of the adjusting means is changed, based on the measured value of the average deviation obtained for each of the plurality of control values. Means for determining the adequacy of the combustion state of the engine based on the difference between the predicted value of the mean deviation and the measured value of the mean deviation actually measured after the change of the control value. Therefore, even if the engine is in the combustion stable region, even if the engine rotation is apt to remarkably change, it is erroneously determined whether or not the combustion is in the stable combustion state by executing the roughness control. It is possible to make an accurate determination without doing so and effectively prevent the engine from becoming misfired, and to bring the ignition timing close to the combustion stability limit to improve fuel efficiency.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an engine including a control device according to an embodiment of the present invention.

FIG. 2 is a functional block diagram of a control unit.

FIG. 3 is a functional block diagram showing a specific configuration of target load detection means.

FIG. 4 is a map showing a region setting for air-fuel ratio control.

FIG. 5 is a diagram showing a detected plate and a crank angle sensor for detecting a crank angle.

FIG. 6 is an explanatory diagram showing changes in stroke, torque, and angular velocity of each cylinder of a 4-cylinder 4-cycle engine.

FIG. 7 is an explanatory diagram showing a correlation between combustion pressure and angular velocity fluctuation.

FIG. 8 is a diagram showing angular velocity fluctuations due to noise-like elements.

FIG. 9 is a diagram showing data after a process of removing a 0.5th-order engine rotation component and an integral multiple thereof from the angular velocity data.

FIG. 10 is a diagram showing data after performing a process as a high-pass filter for removing a component in a frequency range lower than 0.5th order from the above data.

FIG. 11 is a functional block diagram showing a specific configuration of roughness control means.

FIG. 12 is a characteristic diagram showing a correspondence relationship between ignition timing and injection timing and a combustion stable region.

FIG. 13 is a flowchart showing a main control operation for setting ignition timing and injection timing.

FIG. 14 is a flowchart showing a main control operation of roughness control.

FIG. 15 is a flowchart showing a complementary control operation of control data.

FIG. 16 is a characteristic diagram showing the influence of the correction control operation water temperature of the ignition timing and the injection timing on the learned value.

FIG. 17 is a diagram showing a relationship between an air-fuel ratio, ignition timing, roughness and NOx emission amount.

FIG. 18 is a graph showing how the average deviation changes when the roughness control is executed.

FIG. 19 is a time chart showing a change state of ignition timing according to the example of the present invention.

FIG. 20 is a graph showing a correspondence relationship between ignition timing and target load.

FIG. 21 is a time chart showing a change state of ignition timing according to a conventional example.

[Explanation of symbols]

28 Injector (adjusting means) 41 Target load setting means 45 Angular velocity fluctuation detecting means 46 Roughness control means 46a Mean deviation measurement means 46b Prediction value calculation means 46c Judgment means 46d control value setting means 46e storage means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 45/00 358 F02D 45/00 358C 362 362J 370 370B 376 376B 41/02 325 41/02 325H 41/14 310 41/14 310L 41/22 335 41/22 335A 43/00 301 43/00 301B 301E 301J F02P 5/15 F02P 5/15 K (72) Inventor Kiyotaka Mamiya 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. F-term (reference) 3G022 AA07 EA01 EA07 GA05 GA06 3G084 BA09 BA15 BA17 DA04 DA07 DA27 DA28 EB06 EB12 EB25 EC04 FA01 FA02 FA07 FA10 FA20 FA33 FA34 FA38 3G301 HA01 HA18 JA21 JB09 KA06 KA23 MA01 MA42 NC01 NA01 NA18 NC01 NA02 NA01 PA01Z PA09Z PA10Z PE01Z PE02Z PE03Z PF03Z

Claims (9)

[Claims] 1. An angular velocity fluctuation detecting means for detecting an angular velocity fluctuation of engine rotation, an adjusting means for adjusting a combustion state of the engine, and a control value of the adjusting means for maintaining the combustion stability of the engine within a certain range. In an engine control device having a roughness control means for setting, an average deviation measuring means for actually measuring an average deviation of the angular velocity fluctuations for each of a plurality of control values set by the roughness control means in the same operating state of the engine, and , A predicted value calculation means for calculating a predicted value of the average deviation when the control value of the adjusting means is changed, based on an actual measured value of the average deviation obtained for each of a plurality of control values, and prediction of the average deviation And a determination unit that determines whether the combustion state of the engine is appropriate based on the difference between the measured value and the measured value of the average deviation measured after the change of the control value. Control device for the engine. 2. An angular velocity fluctuation detecting means for detecting an angular velocity fluctuation of engine rotation, an adjusting means for adjusting a combustion state of the engine, and a control value of the adjusting means for maintaining combustion stability of the engine within a certain range. In an engine control device having a roughness control means for setting, an average deviation measuring means for actually measuring an average deviation of the angular velocity fluctuations for each of a plurality of control values set by the roughness control means in the same operating state of the engine, and , A predicted value calculation means for calculating the predicted value of the average deviation when the control value of the adjusting means is changed, based on the measured value of the average deviation obtained for each of the plurality of control values, and predicted at the time of the previous control Determination means for determining whether the difference between the predicted value of the average deviation and the measured value of the average deviation actually measured after the change of the control value is within an allowable range; Control value setting means for setting the control value of the adjusting means in the direction of improving the combustion stability of the engine when it is determined that the difference between the predicted value of the uniform deviation and the actual measurement value is outside the allowable range; Is provided in the roughness control means. 3. The average deviation predicted value when the control value is changed is calculated by the least squares method based on a plurality of latest measured values actually measured by the average deviation measuring means. The engine control device according to item 1 or 2. 4. The predictive value of the average deviation when the control value is changed is obtained by the successive approximation method based on the latest measured values measured by the average deviation measuring means. The engine control device according to item 1 or 2. 5. The average deviation of the angular velocity fluctuations measured by the average deviation measuring means for each of a plurality of control values is classified for each operating area divided into a plurality of areas according to the engine speed and the engine load. The stored value of the average deviation stored in the operating region, which is stored in the engine and changed to a specific operating region, is read out and used for controlling the adjusting means. The engine control device according to any one of the claims. 6. A large amount of stored data of average deviation,
6. The control device according to claim 5, wherein the data in the operating region in which the control value shifts toward the combustion stability limit is large is reflected in the operating region in which the average deviation memory data is small and is used for the control of the adjusting means. Engine controller. 7. When changing the control value of the adjusting means toward the combustion stability limit, the number of times that the actual deviation of the average deviation is judged to be outside the allowable range is judged by the judging means,
7. The engine control device according to claim 2, wherein the larger the number of times, the smaller the change amount of the control value is set. 8. A lean combustion mode in which the air-fuel ratio in the combustion chamber is made larger than the stoichiometric air-fuel ratio, and a rich combustion mode in which the air-fuel ratio is made substantially stoichiometric or smaller than the stoichiometric air-fuel ratio, depending on the operating state of the engine. And an air-fuel ratio control means for controlling so as to switch over, and based on a control value set by the roughness control means in an operating state of the lean combustion mode, used for controlling the engine at the time of transition to the rich combustion mode. 8. The engine control device according to claim 2, further comprising a target load setting means for setting a target load. 9. In the lean combustion mode operating condition, the control values of the adjusting means are set for each of the operating regions divided into a plurality of regions according to the engine speed and the engine load, and the control values are set to these control values. 9. The engine control apparatus according to claim 8, wherein an average control value of the entire lean combustion mode is obtained based on the average control value, and a target load at the time of shifting to the rich combustion mode is set according to the average control value.