JPH03134249A - Combustion condition detecting device and ignition timing control device for engine - Google Patents

Abstract

PURPOSE:To make a combustion condition judgeable for whether it is good or not as an absolute amount by comparing a mean differential speed of the concerned cylinder with a preset fixed limit differential speed to estimate the combustion condition of the concerned cylinder. CONSTITUTION:From an engine speed in a section, where work is not performed by combustion between cylinders in a combustion stroke in this time and the next time, and from an engine speed in a section, where work is not performed by combustion in the preceding time, a differential speed of the concerned cylinder is calculated in a differential speed calculating means 42a, further a mean differential speed of the concerned cylinder is calculated in an calculating means 42b. The mean differential speed of the concerned cylinder is compared with fixed upper and lower limit values, preset in discriminating means 42d, 42e of a combustion condition estimating means 42c, with a combustion condition of the concerned cylinder estimated. Thus, the combustion condition of each cylinder can be accurately grasped.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an engine that estimates the combustion state of each cylinder based on the engine rotational speed and variably sets the ignition timing according to the estimated combustion state. The present invention relates to a combustion state estimating means and an ignition timing control device.

[Problems to be solved by conventional technology and inventions] In recent years, there has been a trend to keep engine idle speeds low due to demands such as improved fuel efficiency and quietness. Comfort and starting performance are significantly affected.

Generally, this variation in rotation speed is thought to be caused by variations in the combustion state between cylinders, and this variation in combustion state is caused by: - Non-uniform intake air distribution ratio due to the complexity of the intake pipe shape, intake air interference between cylinders, etc. ■ Slight differences in combustion temperature between each cylinder due to the cooling route; ■ Manufacturing variations in the combustion chamber volume of the joint cylinder, piston shape, etc.; ■ Differences in fuel injection amount due to injector manufacturing errors, etc. This is thought to be caused by slight variations in the air-fuel ratio of the cylinders, etc.

Therefore, by controlling the combustion state of each cylinder almost uniformly, the idle rotation speed can be made smooth.

By the way, as a means to detect the combustion state of each cylinder,
For example, as disclosed in Japanese Patent Application Laid-Open No. 62-55461, an in-cylinder pressure sensor is placed facing the combustion chamber of each cylinder, and the combustion state is estimated from the peak value of the combustion pressure detected by this in-cylinder pressure sensor. What it does is known.

However, this in-cylinder pressure sensor is relatively expensive, and installing it in each cylinder increases the product cost.Furthermore, it is necessary to drill a hole in the cylinder head for installation, which makes it difficult to install in existing engines. difficult to adopt.

On the other hand, for example, JP-A-59-82534, JP-A-63-196448@, JP-A-63-198473
As disclosed in Japanese Utility Model Publication No. 63-202771, the instantaneous engine rotation speed NLi before combustion of each cylinder #1 (i = 1 to 4) and the instantaneous engine speed after combustion Differential rotational speed ΔNi which is the difference between rotational speed 1' and lll
(ΔN1=tlli-N[;) is determined for each cylinder,
This differential rotation speed Ni is made uniform (that is, Δx+ =0
) to smooth out the idle speed.

This prior art focuses on the fact that there is a correlation between the combustion state of each cylinder and the differential rotational speed ΔNi, and uses the average value ΔNAi of all cylinders of the differential rotational speed ΔNi obtained for each cylinder as a reference value. We are trying to estimate the combustion state of that cylinder based on the deviation from the reference value zNAi, but since the reference value ΔNAi is the average value of the gold cylinders, this reference value zNAi itself is always likely to fluctuate depending on the combustion state. When the value ΔNAi changes, the combustion state factors of other cylinders #1 to #4 when determining the reference value ΔNAi will be included in the combustion state of each cylinder estimated based on this standard 1a lUN Ai, It becomes difficult to accurately grasp the combustion state of each cylinder.

As a result, the ignition timing correction value and fuel injection amount correction value for each cylinder, which are set based on the estimated combustion state, are likely to deviate from each other, and there is a limit to the controllability of the engine speed during idling operation.

[Object of the Invention] The present invention has been made in view of the above circumstances, and can be easily applied to existing engines, prevents a rise in parts costs, and moreover accurately grasps the combustion state of each cylinder. As a result, the ignition timing correction value can be set appropriately for each cylinder, which stabilizes the idle rotation speed, guarantees comfort and quietness, and also provides good starting performance. It is an object of the present invention to provide an engine combustion state detection device and an ignition timing control device that can be obtained.

[Means for Solving the Problems] (1) In order to achieve the above object, the first engine combustion state detection device according to the present invention detects the work caused by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder. differential rotational speed calculation means for calculating a differential rotational speed of the relevant cylinder by comparing an engine rotational speed in an area where no work is being performed and an engine rotational speed in an area where no work is being performed due to the previous combustion; an average difference rotational speed calculation means for calculating an average difference rotational speed of the cylinder from the current difference rotational speed of the cylinder calculated by the calculation means and the previous average difference rotational speed of the cylinder;
The combustion state estimation means compares the average difference rotational speed of the cylinder calculated by the average difference rotational speed calculation means with a fixed limit difference rotational speed set in advance to estimate the combustion state of the cylinder. be.

(2) In addition, in order to achieve the above object, the second engine combustion state detection device according to the present invention detects an engine in a section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder. a difference angular acceleration calculation means for calculating a difference angular acceleration of the cylinder by comparing the angular acceleration with the engine angular acceleration in a section where no work is being done due to the previous combustion; an average difference angular acceleration calculation means for calculating the average difference angular acceleration of the cylinder from the current difference angular acceleration of the cylinder and the previous average difference angular acceleration of the cylinder; The combustion state estimation means compares the average difference angular acceleration with a preset fixed limit difference angular acceleration to estimate the combustion state of the cylinder.

(3) In addition, in order to achieve the above object, the third engine combustion state detection device according to the present invention includes an engine in a section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder. a difference period calculation means for calculating a difference period of the cylinder by comparing the period with an engine period in a section where no work is being done due to previous combustion; and a difference period of the current cylinder calculated by the difference period calculation means. , an average difference period calculation means for calculating the average difference period of the cylinder from the previous average difference period of the cylinder; the average difference period of the cylinder calculated by the average difference period output means; and a preset fixed value. The combustion state estimating means compares the combustion state with a limit difference period to estimate the combustion state of the cylinder.

(4) In addition, in order to achieve the above object, the fourth engine combustion state detection device according to the present invention detects an engine in a section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder. a difference angular velocity calculation means for calculating a difference angular velocity of the cylinder by comparing the angular velocity with the engine angular velocity in a section where no work is being done due to previous combustion; and a current difference angular velocity of the cylinder calculated by the difference angular velocity calculation means. , an average difference angular velocity output means for calculating the average difference angular velocity of the cylinder from the previous average difference angular velocity of the cylinder, the average difference angular velocity of the cylinder calculated by the average difference angular velocity calculation means, and a preset fixed value. The combustion state estimation means compares the combustion state with the limit difference angular velocity to estimate the combustion state of the cylinder.

(5) Furthermore, in order to achieve the above object, the first engine ignition timing control device according to the present invention includes an engine load setting means for setting the engine load based on the engine rotation speed and the intake air amount; The basic ignition timing setting means sets the basic ignition timing for each cylinder based on the engine load and engine speed set by the means, and the basic ignition timing setting means sets the basic ignition timing for each cylinder based on the engine load set by the means and the engine speed. differential rotational speed calculation means for calculating a differential rotational speed of the relevant cylinder by comparing an engine rotational speed in a section in which no work is being performed and an engine rotational speed in a section in which no work is being done due to the previous combustion; An average difference rotation speed calculation means for calculating an average difference rotation speed of the cylinder from the calculated current difference rotation speed of the cylinder and the previous average difference rotation speed of the cylinder, and calculation by the average difference rotation speed calculation means. a combustion state estimation means for estimating the combustion state of the cylinder by comparing the average difference rotation speed of the cylinder concerned with a fixed limit difference rotation speed set in advance; If it is determined that the rotation speed is lower than the fixed limit difference rotation speed, the ignition timing is advanced by the set angle, and if it is determined that the average rotation speed difference is higher than the fixed limit rotation speed, the ignition timing is retarded by the set angle. With the correction value to
cylinder-specific learning correction value updating means for updating the learning correction value of the cylinder; and correcting the basic ignition timing set by the basic ignition timing setting means with the learning correction value updated by the cylinder-specific learning correction value updating means. The apparatus also includes ignition timing setting means for setting the ignition timing of the cylinder.

(6) Also, in order to achieve the above object, a second method according to the present invention is provided.
The ignition timing control device for the engine includes an engine load setting means that can set the engine load based on the engine speed and intake air amount, and a basic control system based on the engine load set by the engine load setting means and the engine speed. A basic ignition timing setting means that sets the ignition timing for each cylinder, engine angular acceleration in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder, and the engine angular acceleration that is not doing work due to combustion in the previous combustion stroke. difference angular acceleration calculation means for calculating the difference angular acceleration of the relevant cylinder by comparing the engine angular acceleration of the section where no an average difference angular acceleration calculation means for calculating the average difference angular acceleration of the cylinder from the previous average difference angular acceleration of the cylinder; an average difference angular acceleration of the cylinder calculated by the average difference angular acceleration calculation means; and a preset fixed value. If the combustion state estimating means estimates the combustion state of the cylinder by comparing the difference angular acceleration with the limit difference angular acceleration, and the combustion state estimation means determines that the average difference angular acceleration is lower than the fixed limit difference angular acceleration, ignition is performed. The learned correction value for the cylinder is updated with a correction value that advances the timing by a set angle and retards the ignition timing by a set angle if it is determined that the average differential rotational speed is higher than the fixed limit rotational speed. Ignition timing for setting the ignition timing of the cylinder by correcting the basic ignition timing set by the cylinder-specific learning correction value updating means and the basic ignition timing setting means with the learning correction value updated by the cylinder-specific learning correction value updating means. and setting means.

(7) In addition, in order to achieve the above object, a third engine ignition timing control device according to the present invention includes an engine load setting means for setting an engine load based on the engine rotation speed and an intake air amount; The basic ignition timing setting means sets the basic ignition timing for each cylinder based on the engine load and engine speed set by the means, and the basic ignition timing setting means sets the basic ignition timing for each cylinder based on the engine load set by the means and the engine speed. difference period calculation means for calculating the difference period of the cylinder by comparing the engine period of the section where no work is done by the previous combustion with the engine period of the section where no work is done due to the previous combustion; An average difference period calculation means that calculates the average difference period of the cylinder from the current difference period and the previous average difference period of the cylinder; and an average difference period of the cylinder calculated by the average difference period calculation means. Combustion state estimating means estimates the combustion state of the cylinder by comparing it with a set fixed limit difference period, and if the combustion state estimating means determines that the average difference period is lower than the fixed limit difference period, ignition is performed. The learned correction value for the cylinder is updated with a correction value that advances the timing by a set angle and retards the ignition timing by a set angle if it is determined that the average differential rotational speed is higher than the fixed limit rotational speed. Cylinder-specific learning correction value updating means;
ignition timing setting means for setting the ignition timing of the cylinder by correcting the basic ignition timing set by the basic ignition timing setting means with the learning correction value updated by the cylinder-specific learning correction value updating means. .

(8) In addition, in order to achieve the above object, a fourth engine ignition timing control device according to the present invention includes an engine load setting means for setting an engine load based on the engine rotation speed and an intake air amount; The basic ignition timing setting means sets the basic ignition timing for each cylinder based on the engine load and engine speed set by the means, and the basic ignition timing setting means sets the basic ignition timing for each cylinder based on the engine load set by the means and the engine speed. difference angular velocity calculation means for calculating the difference angular velocity of the cylinder by comparing the engine angular velocity of the section where no work is done by the previous combustion with the engine angular velocity of the section where no work is done due to the previous combustion; An average difference angular velocity calculation means for calculating the average difference angular velocity of the cylinder from the current difference angular velocity and the previous average difference angular velocity of the cylinder; and an average difference angular velocity of the cylinder calculated by the average difference angular velocity calculation means; Combustion state estimating means estimates the combustion state of the cylinder by comparing the set fixed limit difference angular velocity, and if the combustion state estimation means determines that the average difference angular velocity is lower than the fixed limit difference angular velocity, ignition is performed. The learned correction value for the cylinder is updated with a correction value that advances the timing by a set angle and retards the ignition timing by a set angle if it is determined that the average differential rotational speed is higher than the fixed limit rotational speed. Ignition timing for setting the ignition timing of the cylinder by correcting the basic ignition timing set by the cylinder-specific learning correction value updating means and the basic ignition timing setting means with the learning correction value updated by the cylinder-specific learning correction value updating means. and setting means.

[Function] (1) The first engine combustion state detection device with the above configuration first detects the engine rotation speed in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder. The differential rotational speed of the relevant cylinder is calculated by comparing the engine rotational speed in the section where no work is being done due to the previous combustion. The average differential rotational speed of the cylinder is calculated from the previous average differential rotational speed of the cylinder.

Then, the combustion state of the cylinder is estimated by comparing the average differential rotational speed of the cylinder with a preset fixed limit rotational speed difference.

(2) The second engine combustion state detection device with the above configuration first detects the engine angular acceleration in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder, and the previous engine angular acceleration. The difference angular acceleration of the relevant cylinder is calculated by comparing the engine angular acceleration in the section where no work is being done by combustion, and then this calculated difference angular acceleration of the relevant cylinder this time is compared with the previous average of this cylinder. The average differential angular acceleration of the cylinder is calculated from the differential angular acceleration.

Then, the combustion state of the cylinder is estimated by comparing the average differential angular acceleration of the cylinder with a preset fixed limit differential angular acceleration.

(3) The third engine combustion state detection device with the above configuration first detects the engine cycle in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder, and the previous combustion The difference cycle of the relevant cylinder is calculated by comparing the engine cycle of the section where no work is being done by Calculate the average difference period of the cylinders.

Then, the combustion state of the cylinder is estimated by comparing the average difference cycle of the cylinder with a preset fixed limit difference cycle.

(4) The fourth engine combustion state detection device with the above configuration first detects the engine angular velocity in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder, and the previous combustion state detection device. Calculate the differential angular velocity of the cylinder by comparing it with the engine angular velocity in the section where no work is being done.
Next, the average differential angular velocity of the cylinder is calculated from the calculated current differential angular velocity of the cylinder and the previous average differential angular velocity of the cylinder.

Then, the combustion state of the cylinder is estimated by comparing the average differential angular velocity of the cylinder with a preset fixed limit differential angular velocity.

(5) The first engine ignition timing control device configured as described above first sets the engine load based on the engine speed and the intake air M, and then sets the basic ignition timing based on the engine load and the engine speed. Set for each cylinder.

Then, compare the engine rotational speed in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder with the engine rotational speed in the section where no work is being done by combustion in the previous combustion stroke. Calculate the differential rotational speed of the relevant cylinder,
The average differential rotational speed of the cylinder is calculated from the calculated current differential rotational speed of the cylinder and the previous average differential rotational speed of the cylinder.

After that, the combustion state of the cylinder is estimated by comparing the average rotational speed difference of the cylinder with a preset fixed limit rotational speed difference, and it is determined that this average rotational speed difference is lower than the fixed limit rotational speed. If this occurs, the ignition timing is advanced by the set angle, and if it is determined that the above-mentioned average difference rotational speed is higher than the above-mentioned fixed limit difference rotational speed, the ignition timing is retarded by the set angle. Update.

Then, the basic ignition timing is corrected using the updated learning correction value to set the ignition timing for the cylinder.

(6) The second engine ignition timing control device configured as described above first sets the engine load based on the engine speed and the intake air, and then sets the basic ignition timing based on the engine load and the engine speed. Set for each cylinder.

Then, the engine angular acceleration in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder, and the work done by the previous combustion! The difference angular acceleration of the relevant cylinder is calculated by comparing the engine angular acceleration of the section where ■ is not performed, and the difference angular acceleration of the relevant cylinder is calculated from the current difference angular acceleration of the relevant cylinder and the previous average difference angular acceleration of this cylinder. Calculate the average differential angular acceleration of the cylinders.

Thereafter, the combustion state of the cylinder is estimated by comparing the average differential angular acceleration of the cylinder with a preset fixed limit differential angular force of 1 degree, and if this average differential angular acceleration is lower than the fixed limit differential angular acceleration, the combustion state of the cylinder is estimated. If it is determined that the ignition timing is advanced by the set angle, and if it is determined that the above-mentioned average difference angular acceleration is higher than the fixed limit difference angular acceleration, the ignition timing is retarded by the set angle.The learning correction for the cylinder is performed using the correction value. Update the value.

Then, the basic ignition timing is corrected using the updated learning correction value to set the ignition timing for the cylinder.

(7) The third engine ignition timing control device configured as described above first sets the engine load based on the engine speed and the intake air amount, and then sets the basic ignition timing based on the engine load and the engine speed. Set for each cylinder.

Then, the engine cycle in the section where no work is done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder,
The difference cycle of the relevant cylinder is calculated by comparing the engine cycle of the section where no work is being done due to the previous combustion, and the difference cycle of the relevant cylinder is calculated from this calculated difference cycle of this time and the previous average difference cycle of this cylinder. Calculate the average difference period of the cylinders.

Then, the combustion state of the cylinder is estimated by comparing the average difference period of the cylinder with a preset fixed limit difference period, and if it is determined that the average difference period is lower than the fixed limit difference period, the ignition is started. The timing is retarded by a set angle, and if it is determined that the average difference cycle is higher than the fixed limit difference cycle, the stroke correction value for the cylinder is updated with a correction value that advances the ignition timing by a set angle.

Then, the basic ignition timing is corrected using the updated learning correction value to set the ignition timing for the cylinder.

(8) The fourth engine ignition timing control device with the above configuration first sets the engine load based on the engine speed and the intake air amount, and then sets the basic ignition timing based on the engine load and the engine speed. Set for each cylinder.

Then, the engine angular velocity in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder is compared with the engine angular velocity in the section where no work is being done by combustion in the previous combustion stroke. Then, the average differential angular velocity of the cylinder is calculated from the calculated current differential angular velocity of the cylinder and the previous average differential angular velocity of the cylinder.

After that, the combustion state of the cylinder is estimated by comparing the average differential angular velocity of the cylinder with a preset fixed limit differential angular velocity, and if it is determined that this average differential angular velocity is lower than the fixed limit differential angular velocity, the ignition is started. The timing is determined by the set angle advance time, and if it is determined that the above average difference angular velocity is higher than the above fixed limit difference angular velocity, the ignition timing is retarded by the set angle.
Update the learning correction value for the cylinder.

Then, the basic ignition timing is corrected using the updated learning correction value to set the ignition timing for the cylinder.

[Embodiments of the invention] Hereinafter, the present invention will be explained in detail based on the drawings.

1 to 8 show a first embodiment of the present invention;
The figure is a functional block diagram of the control device, Figure 2 is a conceptual diagram of the engine control system, Figure 3 is a front view of the crank rotor and crank angle sensor, Figure 4 is a front view of the cam rotor and cam angle sensor, and Figure 5 is a front view of the cam rotor and cam angle sensor. is a conceptual diagram of the basic ignition timing map, Figure 6 is a time chart of cylinder pressure fluctuation, crank pulse, cam pulse, and engine speed, Figure 7 is a flowchart showing the combustion state detection procedure, and Figure 8 is the ignition timing. It is a flowchart which shows a control procedure.

(Configuration) Reference numeral 1 in the figure is the engine body, and the figure shows a 4-cylinder horizontally opposed engine. An intake manifold 3 is communicated with the intake port 2a formed in the cylinder head 2 of the engine body 1, and a throttle chamber 5 is communicated upstream of the intake manifold 3 via an air chamber 4. An air cleaner 7 is attached via the intake pipe 6.

Further, an intake air amount sensor (in the figure, a hot wire air flow meter) 8 is interposed immediately downstream of the air cleaner 7 in the intake pipe 6, and a throttle valve 5a provided in the throttle chamber 5 is provided. A throttle opening sensor 9a and an idle switch 9b for detecting a fully open throttle valve are connected to the throttle opening sensor 9a.

Further, an injector 10 is disposed immediately downstream of each intake boat 2a of each cylinder of the intake manifold 3. Furthermore, for each cylinder of the cylinder head 2,
A spark plug 11 is attached that exposes the ignition part at the tip to the combustion chamber. Note that an ignition coil 11a is integrally attached to the ignition plug 11.

Further, the injector 10 is communicated with a fuel tank 13 via the fuel passage, and a fuel pump 14 is interposed above the fuel passage.

Further, a crank rotor 15 is pivotally attached to the crankshaft 1b of the engine main body 1, and a crank angle sensor 16 consisting of an electromagnetic pickup or the like for detecting the crank angle is provided on the outer periphery of the rotor 15, and a crank rotor 15 is mounted on the crankshaft 1b. A cam rotor 17 is pivotally attached to a camshaft 1c that rotates by 1/2 relative to the camshaft 1c, and a cam angle sensor 18 is provided on the outer periphery of the cam rotor 17.

As shown in FIG. 3, projections 15a, 15b, and 15c are formed on the outer periphery of the crank rotor 15. These protrusions 15a, 15b, 15c are located before the compression top dead center of each cylinder (
BTDC) θ1. θ2. It is formed at the position θ3,
A periodic element 1.2 (here, child=1/ω ω: angular velocity) is calculated from the transit time between the protrusions 15a and 15b, and a period f2.3 is calculated from the transit time between the protrusions 15b and 15c. Further, the protrusion 15b indicates a reference crank angle when setting the ignition timing.

As shown in FIG. 6, the crank angles BTDCθ2. θ3 is set before and after the ignition timing during idling operation (time > ADV. Generally, the ignition timing during idling operation is around 20°C BTDC,
Even if the engine is ignited at this crank angle, the combustion pressure will not rise rapidly until about 10'CA.

Further, as shown in FIG. 6, in the embodiment, the opening timing of the exhaust valve of each cylinder is set to be slightly retarded than the ignition reference crank angle BTDCθ2 of the next combustion cylinder.
Generally, the combustion pressure immediately after the exhaust valve is opened drops rapidly, so at the crank angle BTDCθ3, there is almost no effect of the combustion pressure.

Therefore, the crank angle 03 of the protrusion 15c is set to BTD.
If set to the advance side from C10'CA, the above protrusion 15
The section between the crank angles BTDC θ2 and θ3 of b and 15c is almost unaffected by the combustion between the cylinders, that is, the section where no work is done by the combustion between one combustion stroke cylinder and the next combustion stroke cylinder. become.

Further, as shown in FIG. 4, cylinder discrimination protrusions 17a, 17b, and 17C are formed on the outer periphery of the cam rotor 17. The protrusion 17a is #3. It is formed at the position θ4 after the compression top dead center (ATDC) of the #4 cylinder, and the protrusion 17b
consists of three protrusions, the first of which is formed at the position θ5 after compression top dead center (ATDC) of the #1 cylinder, and furthermore, the protrusion 17c consists of two protrusions, the first of which is formed at a position θ6 after compression top dead center (ATDC) of #2 cylinder.

In addition, in the example shown in the figure, θ1=97℃A, θ2=65℃△
, θ3=10℃A1θ4=20℃A, θ5=5℃A1θ
6=20℃A1θ(2-3)=55℃A, and with this arrangement, as shown in FIG. It can be determined that the crank pulse detected by the crank angle sensor 16 is a signal indicating the crank angle of the #3 cylinder.

Also, after the cam pulse of θ5, θ4 (protrusion 23a
), it can be determined that the subsequent crank angle detected by the sensor 16 indicates the crank angle of the #2 cylinder. Similarly θ6
The crank pulse after detecting the cam pulse of (protrusion 17c) indicates the crank angle of the #4 cylinder, and
If a cam pulse of θ4 (protrusion 17a) is detected after the cam pulse of 06, it can be determined that the crank pulse detected thereafter does not indicate the crank angle of the #1 cylinder.

Further, after the cam pulse is detected by the cam angle sensor 18, it can be determined that the crank pulse detected by the crank angle sensor 16 indicates the reference crank angle (θ1) of the cylinder.

On the other hand, a knock sensor 19 is fixedly installed on the engine body 1 to detect knock from vibration of the engine body 1,
Further, a cooling water temperature sensor 20 faces a live cooling water passage (not shown) formed in the intake manifold 3.

Further, an 02 sensor 22 faces the exhaust pipe 21 communicating with the exhaust port 2b of the cylinder head 2. Note that 23 is a catalytic converter, and 24 is a vehicle speed sensor.

(Circuit configuration of control device) On the other hand, reference numeral 31 is a control device consisting of a microcomputer, etc., and a CPU (central processing unit) 32, ROM 33, RAM 34, and I10 interface 35 of this control device 31 are connected via a path line 36. Each sensor 8.9a, 16.18.19, 20 is connected to the input port of this I10 interface 35.
．． 22, 24, and the idle switch 9b are connected, and the spark plug 11 is connected to the output port of the I10 interface 35 via the igniter 25, and the injector 10 is connected via the drive circuit 38. ing.

The ROM 33 stores control programs, fixed data, and the like. Fixed data includes a basic ignition timing map MPθBAβF, which will be described later.

Further, the RAM 34 stores the output signals of the sensors after data processing and the data processed by the CPU 32.

Further, the CPU 32 calculates the fuel injection pulse width or ignition timing for the injector 10 based on various data stored in the RAM 34 according to the control program stored in the ROM 33.

(Functional configuration of control bag @ 31) As shown in FIG. 1, the functions related to ignition timing control of the control device 31 are sensor input data focusing means 41, combustion state detecting means 42, and ignition timing calculating means 43. It is made up of.

The sensor input data calculation means 41 is composed of cylinder discrimination means 41a1, crank pulse discrimination means 41b, period calculation means 41C, engine speed calculation means 41d, idle discrimination means 41e, and intake air ff1tX output means 41f. ing.

Further, the combustion state detection means 42 is connected to the differential rotational speed calculation means 4.
2a, an average difference rotational speed calculating means 42b, a combustion state estimation means 42c, and an average difference rotational speed updating means 42f, and the combustion state estimation means 42c comprises:
Fixed upper limit value determining means 42d, fixed lower limit value determining means 42e
Consists of.

Roughly speaking, the ignition timing setting means 43 includes an engine load setting means 43a, a basic ignition timing setting means 43b, a knock control value setting means 43C1, a learned value limit determining means 43
d, cylinder-specific learning correction value updating means 43Q, ignition timing setting means 43h, ignition time setting means 431, timer means 43j
, and the ignition selection means 43, and the learned value limit determination means 43d comprises the learned value retard limit determination means 4.
3e, and learning value advance angle limit determining means 43f.

:Functional configuration of the sensor input data calculation means 41: In the cylinder discrimination means 41a, the cam rotor 17 of the cam angle sensor 18
Based on the cam pulses that detect the protrusions 17a to 17c,
It is determined which cylinder # (i=1.3.2.4) the crank pulse detected by the crank angle sensor 16 indicates the crank angle.

The crank pulse determining means 41b determines which protrusion 15a to 15c is detected by the crank pulse output from the crank angle sensor 16 after the cam pulse output from the cam angle sensor 18.

The period calculating means 41c calculates the elapsed time t1 between the crank pulses that detect θ1 (protrusion 15a) and θ2 (protrusion 15b) determined by the crank pulse discriminating means 42.
．． 2, and the elapsed time t above and the angle (θ1−
Calculate the circumference f] f 1.2 from 02). Further, the period calculating means 41C calculates θ2 (protrusion 15b) and θ3 (protrusion 15C) determined by the crank pulse discriminating means 41b.
The elapsed time t2.3 between the crank pulses for detecting the period is determined from the elapsed time t2.3 and the angle (θ2-θ3) as described above. θ3 is a region where no work is done by combustion between the combustion stroke cylinder and the next combustion stroke cylinder, so the period f2.3 calculated from this interval θ2°θ3 is the rotational speed due to combustion. It is not affected by sudden fluctuations.

The engine rotation speed calculation means 41d calculates the engine rotation speeds N1.2 and NNEW, respectively, based on the Zhou Akiko 1.2 and Zhou Akiko 2.3 calculated by the cycle calculation means 41c (N1.2-60). , -Aa3.7-1NNE
The idle determination means 41e reads the output signal of the vehicle speed sensor 24 and the output signal of the idle switch 9b, and determines whether the vehicle speed S=O (stopped state) and the idle switch ON<throttle fully open). If so, it is determined that the vehicle is idling.

The intake air amount calculation means 41f calculates the intake air amount 1Q based on the output signal of the intake air amount sensor 8.

:Functional configuration of the combustion state detection means 42: In the differential rotation speed calculation means 42a, when the idle operation is determined by the idle determination means 41e, the current rotation speed is calculated based on the period f2.3 calculated by the engine rotation speed calculation means 41d. The engine rotation speed NNEIA and the storage means (R
AM) 34, which was calculated in the previous routine and which is stored in the predetermined address, reads the engine rotational speed NOLD based on the cycle CH2.3, and sets both engine rotational speeds NNEW.
, the differential rotational speed of the cylinder #i determined by the cylinder discriminating means 41a from the difference in NGLD, ! IIIN i (i=
1.3,2. ．． 4) Calculate (JN i =N
NEW-NOLD).

Further, the differential rotational speed calculation means 42a calculates the engine rotational speed N calculated by the engine rotational speed calculation means 41d.
NEW, the engine rotation speed NOLD stored at a predetermined address in the storage means 34 is updated (NOLo
4-NNE14).

As shown in FIG. 6, in the case of a 4-day 4-cylinder engine, the engine rotation speed N N is determined based on the period f2.3.
Since EW is executed every 180°C, the period f2.3 measured between cylinders is common.

Therefore, for example, when focusing on cylinder #i, by subtracting the previously calculated engine speed N0LD from the currently calculated engine speed NNEI4, the differential rotational speed ΔN1 of cylinder #1 is obtained; By setting the engine rotational speed NNEW of the cylinder #1 to NOLD, the differential rotational speed ΔN3 can be obtained from the subsequent engine rotational speed NNE- of the cylinder #3.

The engine speed of each common sliding cylinder is set to N4.
．． 1, N1.3, N3.2, and N2T-4, the differential rotational speed of each cylinder is as follows.

ΔN 1 = N1.3 - N4.1 ΔN5 = N3.2 - N1.3 ΔN 2 = N2.4 - N3.2 ΔN4 = N4.
1 - N1.3 By the way, experiments have revealed that the differential rotational speed 1JNi has a strong correlation with the indicated mean effective pressure and, of course, with the combustion state of the cylinder.

Therefore, as described above, by determining the differential rotational speed ΔNi, it is possible to estimate whether the combustion state (indicated mean effective pressure) of each cylinder #i is good or bad.

The relationship between the differential rotational speed ΔNi and the indicated average effective pressure is shown below.

First, the state in which the engine is rotating is expressed as the table size, I: moment of inertia N: engine rotation speed Ti: commanded torque Tr: friction torque, and simplifying this formula (1), Pi, PF: constants Further, when expressed in terms of pressure, Pi: Indicated mean effective pressure Pf: J! Xi! ! This is the effective pressure loss.

According to experiments, the crank angle for detecting the rotational speed and the crank angle width for calculating the speed were set to θ2.3 as described above.
In other words, if set before and after the combustion stroke, 4 cycles 4
In the case of a cylinder engine, based on the differential rotational speed ΔNi and the temporal change ΔT (180°C A),
) As a result of calculating dN/dt, a very strong correlation is obtained.

In this case, if we consider that the fluctuation of ΔT (180'CA) is negligible and the ByA loss effective pressure Pf is also constant, then from the above equation (3), ΔN=KXPi +PF...(4) holds. do.

Therefore, by determining the differential rotational speed ΔN of each cylinder, the indicated mean effective pressure Pi, that is, the combustion state can be estimated for each cylinder.

Then, the differential rotational speed ΔNi of each cylinder #i is individually “
If it approaches 0'', the combustion state for each cylinder can be made uniform.

On the other hand, in the above equation (3), assuming that the frictional average effective pressure P[ is constant and set it as a constant C, and the proportional constant as K, the following is obtained. Therefore, by determining K and C in advance, the indicated average effective pressure P1 can be calculated as follows. You can ask for it.

According to Equation (5), by differentiating the rotational speed difference ΔN with respect to time, the indicated mean effective pressure Pi can be estimated from the rotational speed difference ΔN with higher accuracy.

The average rotational speed difference calculation means 42b calculates the rotational speed difference ΔN of the cylinder #i calculated by the rotational speed difference calculation means 42a.
i and the previous average differential rotational speed ΔN81(-1) of the cylinder #1 calculated in the previous routine stored at a predetermined address in the storage means (RAM) 34. The current average difference rotational speed ΔNAi is calculated.

This average differential rotational speed aNAi is obtained from the weighted average of the following equation.

ΔNAi=((2-1)XΔNAi(-1)+ΔNi)
/2' r: Weighting coefficient However, the initial average differential rotational speed ΔNAi is assumed to be "OI+".

Note that this average rotational speed difference ΔNAi is calculated for each cylinder.

By determining the average differential rotational speed ΔNAi using a weighted average, it is possible to correct the measurement 2j difference of the cylinder and the variation due to temporal rotational speed fluctuations.

Calculations in the functional blocks described below are executed based on data for each cylinder.

The fixed upper limit value determining means 42d of the combustion state estimating means 42C compares the average differential rotational speed ΔN8 of the cylinder #i calculated by the average differential rotational speed calculating means 42b with the preset fixed limit differential rotational speed lower limit value ΔNU. Compare.

Further, in the fixed lower limit value determining means 42e of the combustion state estimating means 42c, the fixed upper limit value determining means 42d determines that 1U
When it is determined that NAi≦ΔNu, the average differential rotational speed calculation means 42b calculates the average differential rotational speed ΔNAi of the stopped cylinder #i and the preset fixed limit differential rotational speed lower limit value Δ.
Compare with NL.

The fixed limit difference rotational speed upper limit value ΔNu and the fixed limit difference rotational speed lower limit value ΔNL are set based on the upper limit judgment value and lower limit judgment value of the indicated average effective pressure, which are determined in advance through experiments and the like. be.

In the average differential rotation speed updating means 42f, the fixed upper limit value determining means 42d determines that 1UNAi≦ΔNLI, and the fixed lower limit value determining means 42e determines that ΔNAi≧ΔNL.
If it is determined that
If i is within the fixed limit difference rotational speed range (,4Nu≧
, dNAi≧N), or the learned value advance limit determining means 43f constituting the learned value limit determining means 43d of the ignition timing adjusting means 43, which will be described later, determines the learned correction value LADVi.
is on the retard side than the advance angle limit correction value LmtADV (LADVi<LmtADV), or the learned value retard limit determination means 43e determines that the learned correction value IADVi is the retard limit correction value. L mtRT When it is determined that the angle is more advanced than D (lADVt>LmtRTD
), the cylinder #i identified by the cylinder determining means 41a
The previous average differential rotational speed ΔNAi(
-1) is updated with the average difference rotational speed ΔNAi calculated by the average difference rotational speed calculation means 42b (ΔNAi(-1
)←ΔNAi＞.

Further, in the average difference rotation speed updating means 42f, the learned value retard limit determining means 43e1 or the learned value advance limit determining means 43f determines that l ADVi≦l mtRT
D, or l ADVi≧L mtA D When it is determined that V At the average differential rotational speed ΔNAi (i.e., φ), the storage means (RAM
) 34, the previous average differential rotation speed of the cylinder #i stored in the address corresponding to the cylinder #i, 6 N Ai(-
1) Update. Therefore, in this case, the average differential rotational speed l N Ai (-1) of the relevant cylinder is reset (
ΔNAi(-1)←φ).

That is, if the learning correction value LADVi of the cylinder #i exceeds the range of the learning limit correction values LmtRTD and LmtΔDV (lADVi≦lmtRTD, a certain value, LADVi≧LmtADV), the ignition timing described below Calculating means 430 Cylinder-specific learning correction value updating means 43C1
In order to set the learning limit correction values LmtRTD and LmtADV as the limit values of the learning correction value I ADVi (
l ADVi4-L mtRT D or LA
DVi+L mtADV), unless the average differential rotational speed ANA of the corresponding cylinder #i is reset, errors are likely to occur in subsequent calculation results by the average differential rotational speed calculating means 42b.

:Functional configuration of the ignition timing calculating means 43: In the engine load setting means 43a, the engine speed k
Based on the engine speed N1.2 outputted from the output means 41d1'g and the intake air ff1Q calculated by the intake air illll output 41f, the engine load Tp is set by calculation or map search.

In the example shown in the figure, the calculation (Tp = KXQ/
NK: constant).

The basic ignition timing setting means 43b uses the engine speed N1.2 calculated by the engine speed calculation means 41d,
The basic ignition timing map MP is set using the engine load TI) set by the engine load setting means 43a as a parameter.
Search θBASE and find the basic ignition timing (angle) IAsIE from the basic ignition timing data stored in this search area.
Set directly or by interpolation calculation.

As shown in FIG. 5, the basic ignition timing map MPθB
ASE is fixed data stored in the ROM 33, and is composed of a three-dimensional map with engine load Tp and engine speed N1.2 as parameters. Basic ignition timing θBASE
is memorized.

The knock control value setting means 43G compares the output voltage of the knock sensor 19 with a preset reference value for knock determination, and determines that there is no knock if the output voltage of the knock sensor 19 is lower than the reference value for knock determination. Then, the knock control value θNK is set to the advance side at a predetermined crank angle of 10 (θNK←+θ).

Additionally, if the output value of one of the knock sensors is higher than the reference value for knock determination, it is determined that a knock has occurred, and the knock control value θNK is set at a retard amount -〇 that is sufficient to avoid knocking (θNK←θ). .

Learning value retard limit determining means 4 of learning value limit determining means 43d
3e, the learning value advance limit determining means 43f stores the storage means (
Read the cylinder-specific learning correction value LADVi (i=1.3, 2.4) stored in the corresponding address of RAM) 34,
This learning correction value LADV i is compared with a retard angle limit correction value LaHRTD or an advance angle limit correction value L mtADV set in advance through experiments or the like.

In the cylinder-specific learning correction value updating means 43Q, the fixed upper limit value determining means 42d of the combustion state estimating means 42c determines that ΔN A
i> N u, it is determined that the combustion in the cylinder # is too good, and the cylinder-specific learning stored at a predetermined address in the storage means 34 corresponding to the cylinder #i determined by the cylinder determining means 41a is performed. The correction value I ADVi is updated with a value retarded by a predetermined crank angle C (for example, C=1° C.A) (LA port v=L ADVi-C').

Further, in the cylinder-specific learning correction value updating means 430, when the fixed lower limit value determining means 42e of the combustion state estimating means 42C determines that aNAi<ΔNL, it is determined that the combustion in the cylinder #1 is poor, and The cylinder-specific learning correction value L ADVi stored in the address of the storage means (RAM) 34 corresponding to the cylinder #i discriminated by the discriminating means 41a is advanced by a predetermined crank angle C (for example, C-1°C A). Update with the value set (LADVi4-L 8DVi+C)
.

Further, in the cylinder-specific learning correction value updating means 43g, the learning value retardation limit determining means 43e determines that DVi≦L t
ntRTD, that is, when it is determined that the learning correction value LADVi of the cylinder #i exceeds the retardation limit correction LmtRTD, the learning correction value LADVi of the cylinder #i is stored in the storage means (RAM) 34 corresponding to the cylinder #i. The cylinder-specific learning correction value 1-ADVi for the relevant cylinder #i is set as the retardation limit correction value 1 mt.
RT D T: Update (L ADVi4-L mtR
TD).

Further, in the cylinder-specific learning correction value updating means 43Q, the learning value advance limit determining means 43f determines that LADVi≧Li+
tA DV, t, corresponding cylinder #i (7)
Learning correction value I ADVi is advance angle limit correction value L mtA
If it is determined that it exceeds D V, the cylinder-specific learning correction value L ADVi of the cylinder #i stored in the storage means (RAM) 34 corresponding to the cylinder #i is set to the retard limit correction value L ltA. Update with DV ( l ADV
i←L mtA D■). Therefore, the learning correction value LADVi is the limit correction LmtRTD, LmtADV
The limit value is set within that area (LmtAD
V≧1−ADVi≧LmtRTD).

The ignition timing setting means 43h sets the basic ignition timing (angle) f) BAS set by the basic ignition timing setting means 43b.
E is corrected by the knock control value θNK set by the knock control value setting means 43C, and the corresponding cylinder #
Set the ignition timing (angle) θIG of i (θ TG
← θ BASE+ θ NK).

Further, in the ignition timing setting means 43h, when the idle operation is determined by the idle determination means 41e, the corresponding cylinder #i stored in the storage means (RAM) 34
(Cylinder-specific learning correction value L ADV for i = 1.3, 2.4>
i is read, and the basic ignition timing (angle) θBASE set by the basic ignition timing setting means 43b is corrected using the knock control value θNK set by the knock control value setting means 43C and the cylinder-specific learning correction value IADVi. Then, set the ignition timing (angle) θTG for the cylinder #i (θIG←θBASE+ θN + l−8 DVi
).

In the ignition time setting means 43i, the ignition timing setting means 4
Ignition timing (angle) θIG of the cylinder #i set in 3h
Then, the ignition time ADV is set from the cycle f1.2 calculated by the cycle calculation means 41c (ADV=θIGxchi1.2).
2).

The timer means 43j sets the ignition time ADV of the cylinder #i set by the ignition time setting means 43i, and starts timing by using the reference crank angle θ2 for setting the ignition timing detected by the crank pulse determination means 41b as a trigger. However, when the time has elapsed, an ignition signal is output to the ignition selection means 43.

The ignition selection means 43 receives the ignition signal from the timer means 43j and outputs a primary side cutoff signal for the ignition coil 11a to the igniter of the cylinder #i determined by the cylinder determination means 41a.

(Function): Combustion state estimation procedure: Next, the combustion state estimation procedure during idling with the above configuration will be explained according to the flowchart of FIG. Note that this control program is executed for each cylinder.

First, in step 5101, the vehicle speed S and the idle switch output are read, and in step 5102, the
It is determined whether the current driving state is idle based on the vehicle speed S read in step 101 and the idle switch output.

Vehicle speed S=φ, idle switch ON (throttle fully open)
In this case, it is determined to be idle and the process proceeds to step 5103.
Also, vehicle speed S≠φ or idle switch OFF
(throttle all rJIm excluded), it is determined that the vehicle is running and the routine is exited.

Proceeding to step 5103, combustion stroke cylinder #1 (-1, 3, 2
, 4). Next, in step 3104, the crank pulse for detecting BTDC02 and θ3 output from the crank angle sensor 16 is determined by the interruption of the cam pulse.

Then, in step 3105, the elapsed time t2, 3 between crank pulses for detecting BTDCO2, θ3 determined in step 5104, and the above θ2. Angle of θ3 (θ
2-θ3) to calculate the period Chi2.3 (child 2.3
= d t2.3 /d (θ2-θ3)).

Next, in step 3106, the engine rotation speed NNEW is calculated from the periodic element 2.3 calculated in step 5105 above.
).

Thereafter, in step 5107, work is done by combustion in the combustion stroke cylinder #i based on the difference between the engine speed NNEI calculated in step 8106 (and the engine speed N0LD of the cylinder #i calculated in the previous routine). Calculate the differential rotational speed 4Ni in the section where the
Ni4-NNE-NOLD>, in step 8108;
The previous engine rotation speed NOLD stored in a predetermined address of the storage means is updated with the current engine rotation speed NNE- calculated in step 8106 above (NOLD(
-NNE oath).

Then, in step 5109, the differential rotational speed O Ni calculated in step 5107 and the previous average differential rotational speed ΔNAi (-1
), the current average differential rotational speed, 6NAi, is calculated from the weighted average of the weighting coefficient r (aNA+←((2'-1
)XaNAi(-1)+aNi)/2).

Thereafter, in step $110, the average differential rotational speed ΔNAi of the cylinder #i calculated in step 5109 is compared with a preset fixed limit differential rotational speed upper limit value ΔNu, and dNAi>, INu, that is, Average differential rotational speed N
If it is determined that Ai is larger than the fixed limit difference rotational speed upper limit value ΔNu, it is determined that the combustion state of the cylinder #1 is not good, and in step 5111, the combustion state of the cylinder #i that is stored in the predetermined address of the RAM 34 is Learning correction value LADVi (
i=1.3.2.4>, a predetermined crank angle C (for example, C=1℃A) r u angle L ta value r further 1i t le (
LADVi+-LADVi-C).

Then, in step 51 above, the learning correction value 1-ADVi for the cylinder #j calculated in step 6111 above is compared with the preset retard limit correction ffffLmtRTD, and LADVi>LmtRTD in the case of,
Since the cylinder-specific learning correction value ADV i has not yet reached the retard limit, the process jumps to step 5119.

matc, above step 51 above r, LADVi≦1mt
If it is determined that it is RTD, this learning correction value I ADVi has reached the retard limit, so in step 5113, the learning correction value L ADVi of the corresponding cylinder #i stored in the predetermined address of the RAM 34 is adjusted to the retard limit correction. Value 1 +nt
Update with RTD (L ADVi+-LmtRTD).

On the other hand, in step 5110 above, the average differential rotational speed ANA
If it is determined that i is lower than the fixed limit difference rotational speed upper limit value ΔNu (ΔNAi≦ΔNL+), step 511
Proceed to step 4, compare the average differential rotational speed aNAi and the preset fixed limit differential rotational speed lower limit value -NL, and if the average differential rotational speed ΔNAi is lower than the fixed limit differential rotational speed lower limit value ΔNL. ΔNAi<dNL), it is determined that the combustion condition of the cylinder #1 is poor, and the process proceeds to step 5115.
Then, the learning correction value LADVi (i-1, 3, 2, 4) for the cylinder #1 stored at a predetermined address in the RAM 34
is updated with a value obtained by advancing the angle at a predetermined crank angle C (for example, C=1°C) (LADVi4-LADVi10G).

Further, in step 5114, the average differential rotational speed I
If JNAi is determined to be outside the fixed limit rotational speed lower limit value zNL (ΔNAi≧ΔN[), the above average difference rotational speed ΔN
Since Ai is within the setting range (ΔNu≧7NAi≧JN
L>, step 5119 is rejected without updating the learning correction value 1-ADVi.

Then, step 5113. Or step 5
When proceeding from step 117 to step 8118, the above step 5
The average differential rotational speed calculated in step 109, dNAi, is reset (ΔNAi←φ).

Thereafter, in step 5119, the previous average differential rotational speed ΔNAi (-1) stored at a predetermined address in the RAM 34 is converted to the current average differential rotational speed ΔNAi calculated in step 5109 above, or the value reset in step 3118 above. Update with and exit the routine (lUN
Ai(-1)←ΔNAi).

Two-point hole timing control procedure: Next, the ignition timing control procedure will be explained according to the flowchart of FIG. Note that this ignition timing control is executed for each cylinder.

First, in step 5201, the crank pulse and cam pulse are read, and in step 3202, the
Cylinder discrimination is performed from the crank pulse and cam pulse read in step 01.

Next, in step 5203, the BTDCθ1. The crank pulse for detecting θ2 is determined from the interruption of the cam pulse.

Then, in step 5204, the BTDCθ1. The elapsed time t1.2 between crank pulses for detecting θ2 and the angle between θ1 and 02 (θ
1-θ2) to calculate the period f1.2 (child 1.2
= d tl,2 /d (θ1-θ2)).

Next, in step 5205, the engine rotation speed N above is calculated based on the period Chi1.2 calculated in step 5204 (N1.2←(60/2π·fl, 2)×
ω1.2).

After that, in step 3206, intake air MQ is extracted based on the output signal of the intake air direction sensor 8, and in step 520
7, the intake air ωQ calculated in step 8206 above and the engine rotation speed N1 calculated in step 8205 above.
．． 2, calculate the engine load Tp (Tp −
KxQ/N1.2 K: constant).

Then, in step 8208, the basic ignition timing map MPθBASE is searched using the engine load Tp calculated in step 5207 and the engine rotation speed N1.2 calculated in step 5205 as parameters, and the basic ignition timing θBASE is set.

Further, in step 5209, a knock control value θNK is set according to the output signal of the knock sensor 19.

Then, in step 5210, the vehicle speed sensor output and the idle switch output are read, and in step 5211, the vehicle speed S
≠0, or if the idle switch is FF (throttle fully closed and released), it is determined that the idle is released and the process proceeds to step 52 above, and if the vehicle speed is S-0 and the idle switch is ON <throttle fully open) , and the process proceeds to step 5213.

Step 52 In the above step, the basic ignition timing θBASjE set in the step 8208 is corrected by the knock control value θNK set in the step 5209 to calculate the ignition timing θIG (θIG←θB+θN).

On the other hand, if it is determined that the engine is idling and the process proceeds to step 5213, the learning correction value I ADVi of the corresponding cylinder #i set in the combustion state estimation program described above is read out, and the process proceeds to step 5213.
14, the basic ignition timing θBAS[ set in step 5208 above is corrected by the knock control value θNK set in step 5209 above and the learning correction value LADVi read out in step $213 above to determine the ignition timing θ.
Calculate IG (θIG←θBASE+θNK+L
ADVi).

Then, in step 5215, the step 52 described above,
Alternatively, the ignition timing θIG calculated in step 5214
and the period f1.2 calculated in step 5204 above, the ignition time ADV is set (ADV←θIGx fl
, 2).

Next, in step 8216, a timer is set to the ignition time ADV set in step 5215, and step 5
In step 217, time measurement is started using the θ2 pulse as a trigger, and in step 8218, when the ignition time has been reached, an ignition signal is output to the igniter 25 of the corresponding cylinder #i.

In this way, in ignition timing control during idling operation, the learning correction value 1 - ADVir basic ignition timing θB 8 SE, which is the estimated combustion state, is corrected to stabilize the idling rotation speed and significantly reduce vibrations. be done.

In addition, for the combustion state of each cylinder, an average value ΔNAi is determined for each cylinder based on the difference rotational speed ΔNi before and after the combustion stroke of combustion stroke cylinder #i, and this average value ΔNAi and a fixed limit value NU
, NL. Therefore, when determining the combustion state of the cylinder #i, the combustion factors of other cylinders are not included, and therefore, the combustion state of the cylinder can be accurately detected. be able to.

In particular, the burden on the control unit is reduced because the rotational speed detection crank angle is shared in the sections where no work is being done by combustion.

(Second Embodiment) FIGS. 9 to 11 show a second embodiment of the present invention, in which FIG. 9 is a functional block diagram of the control device, FIG. 10 is a flowchart showing the combustion state detection procedure, and FIG. is a time chart of crank pulses, cam pulses, engine speed, and angular acceleration. Note that the means and steps having the same functions as those in the first embodiment are given the same reference numerals as in the first embodiment, and a description thereof will be omitted.

In this embodiment, the combustion state is estimated from the engine angular acceleration instead of the engine rotational speed as in the first embodiment.

Reference numeral 52 in FIG. 9 is a combustion state detection means, which is composed of an angular acceleration calculation means 52a, a difference angular acceleration calculation means 52b, an average difference angular acceleration calculation means 52C, a combustion state estimation means 52d, and an average difference angular acceleration updating means 52g. .

The angular acceleration calculating means 51a calculates the angular acceleration (d14/d
t) Calculate NEW.

In the difference angular acceleration calculation means 52b, the idle determination means 41
If the idling operation is determined by e, the current angular acceleration (dN/dt) NE calculated by the angular acceleration calculation means 52a
- and the angular acceleration (dN/d
t) OLD, and calculate this bidirectional angular acceleration (dN/dt).
14EW, (d14/dt)OL[l] The difference angular acceleration Δ(dN/dt)i (i=1.3.2.4) of the cylinder #i determined by the cylinder discriminating means 41a is expressed as No. 7. (Δ(dN/dt)i = (dN/dt)
NE-(dN/dt)OLD>.

Further, the difference angular acceleration calculation means 42b calculates the angular acceleration (dN/dt) N calculated by the angular acceleration calculation means 518ri.
In the EW, update the angular acceleration (dN/old) 0 [D ((dN/d)
t)OLD←(dN/dt)NEW).

The average difference angular acceleration calculation means 52 cr stores the difference angular acceleration Δ(dN/dt)i of the cylinder #i calculated by the difference angular acceleration calculation means 52b at a predetermined address of the storage means (RAM) 34. Previous average difference acceleration B (dN/dt) A of the cylinder #i calculated in the previous routine
The current average differential angular acceleration Δ(dN/dt)Ai for the cylinder # is calculated from the weighted average with i(-1).

This average difference angular acceleration 1 (dN/dt)Ai is obtained from the weighted average of the following equation.

Δ(dN/dt)Ai= ((2-1) XΔ(dN/
dt)A(-1)) + J (dN/dt)i')
/ 2 'r: Weighting coefficient However, the initial average difference angular velocity Δ(dN/dt) Ai is '
“Set as OI+.

Note that this average differential angular acceleration IJ (dN/dt)Ai is calculated for each cylinder.

Calculations in the functional blocks described below are executed based on data for each cylinder.

The fixed upper limit value determining means 52e of the combustion state estimating means 52d calculates the average differential angular acceleration of the cylinder #i calculated by the average differential angular acceleration calculating means 52c, 4 (dN/dt)Ai,
Preset fixed limit difference angular acceleration upper limit value B (dN/dt
) compare with u.

Further, in the fixed lower limit value determining means 52f of the combustion state estimating means 52d, the fixed upper limit value determining means 52e determines that Δ(
When it is determined that dN/dt)Ai≦Δ(dN/dt)u, the average differential angular acceleration Δ(dN/dt)Ai of the cylinder #i calculated by the average differential angular acceleration calculation means 52C and the preset Fixed limit difference angular acceleration lower limit value Δ(dN/dt)L
Compare with. In addition, the above fixed limit difference angular acceleration upper limit value Δ
(dN/dt)u and the above fixed limit difference angular acceleration lower limit value Δ
(dN/dt)L is set based on an upper limit determination value and a lower limit determination value of the sushi average effective pressure determined in advance through experiments or the like.

In the average difference angular acceleration updating means 52g, the fixed upper limit value determining means 52e determines that 1,5 (dN/dt)Ai≦Δ(dM
/dt)u, and the fixed lower limit determining means 52f determines that Δ(dN/dt)Ai≧Δ(dN/dt)L, that is, the average difference angular acceleration Δ(dN
/dt) If Ai is within the fixed limit difference angular acceleration range (
Δ(dN/dt)u≧1U(dN/dt)^1≧,6
(dN/dt)L ), or in the learned value advance limit determining means 43f that constitutes the learned value limit determining means 43d of the ignition timing calculating means 43, the learned correction value LADVi is determined from the advance limit correction value 1-itADV. If it is determined that the angle is on the retard side (LADV<l-mtADV), or the learned value retard limit determining means 43e sets the learned correction value I ADVi.
is on the advance side than the retard limit correction value Ll1ltRTD]-ADVi>LmtRTD), a predetermined address of the storage means (RAM>34) corresponding to the cylinder #i determined by the cylinder determining means 41a. The previous average difference angular acceleration Δ(dN/dt)A of the relevant cylinder #i stored in
i(-1) is updated with the average difference rotational speed ΔNAi calculated by the average difference angular acceleration calculation means 52c (ΔNAi
(-1)←ΔNAi).

Further, when the average difference angular acceleration updating means 52q determines that 1ADVi≦LmtRTD or L Aov+≧LmtADV in the learned value retard limit determining means 43e or the learned value advance limit determining means 43f,
The average differential angular acceleration Δ(dN/dt)A+ of the cylinder #i calculated by the average differential angular acceleration calculation means 52c should be reset (Δ(dN/dt)Ai←φ), and the reset average differential angular acceleration Δ( dN/dt)Ai (that is, φ), the previous average difference angular acceleration 1 (dN/dt)Ai( -1) is updated. Therefore, in this case, the average differential angular acceleration Δ(
dN/dt) Ai (-1) is reset (Δ(dN
/dt)Ai(-1)←φ).

On the other hand, in the cylinder-specific stroke correction value updating means 43g in the ignition timing calculation means 43, the fixed upper limit value determination means 52e of the combustion state estimation means 52d determines that Δ(dN/dt)Ai>
If it is determined that Δ(dN/dt)u, it is determined that the combustion in the cylinder #1 is too good, and the cylinder #1 is stored at a predetermined address in the storage means 34 corresponding to the cylinder #i determined by the cylinder determining means 41a. The cylinder-specific learning correction value L ADVi is updated with a value that is retarded by a predetermined crank angle C (for example, C = 1°C A) ( L ADVi4-L ADVi-C
).

Further, in the cylinder-specific learning correction updating means 43o, the fixed lower limit value determining means 52f of the combustion state estimating means 52d calculates Δ
When it is determined that (dN/dt)Ai<Δ(dN/dt)L, it is determined that combustion in the cylinder #i is poor, and the storage means (RAM) corresponding to the cylinder #i determined by the cylinder determination means 41a is ) 34 address is set at a predetermined crank angle C (for example, C=
Update with a value advanced by 1℃△) (L ADVi
-IADVi+G).

Next, the procedure for estimating the combustion state during idling according to this embodiment will be explained with reference to the flowchart of FIG. 10. Note that this control program is executed for each cylinder.

When the engine rotation speed N NEW is calculated from the periodizer 2.3 in step 8106, the process advances to step 5301.
Angular acceleration k (dN
/dt) calculate NEW.

Thereafter, in step 5302, the engine angular acceleration (dN/dt) NEWO obtained in step 5301,
Combustion stroke cylinder # from the difference between the engine angular acceleration (LdN/dt) D of the cylinder #i calculated in the previous routine;
Δ(dN/d)
t) i←(dN/dt) NEW −(dN/dt)OL
D), in step 5303, the previous engine angular acceleration (dN/
dt) Update OLD with the current engine angular acceleration (dN/dt) NEW calculated in step 5301 above (
(dN/dt)OLD←(dN/dt)NEW)
.

Then, in step 5304, the difference angular acceleration Δ(dN/dt)i calculated in the above step 5302 and the previous average difference angular acceleration Δ(dN/dt)Ai ( -1), calculate the current average difference angular acceleration Δ(dN/dt)Ai by calculating the weighted average of the weighting coefficient r<1 (dN/dt)Ai←((2r
-1) xd(dN/dt)Ai (-1) 10Δ(
dN/d()i)/2).

Thereafter, in step 5305, the average difference angular acceleration Δ(dN/dt
)^1 and the preset fixed limit difference angular acceleration upper limit value Δ(
dN/dt)u, and Δ(dN/dt)Ai >
Δ(dN/dt)tl, i.e., the average difference angular acceleration Δ
(dN/dt)8 is the fixed limit difference angular acceleration upper limit value Δ(dN
/old) If it is determined that RΔ
A value obtained by retarding the academic regulation correction value I ADVi (i −1, 3, 2, 4>) of the cylinder #i stored at a predetermined address of M34 by a predetermined crank angle C (for example, C=1°C) Updated with 6 (L ADVi4-L ADVi -
C).

Then, the learning correction value I ADVi of the cylinder #i calculated in step 31 r and step 5111 above is compared with the preset retard limit correction value L mtRT D, and if L ADVt > L mtRT D, Since the cylinder-specific learning correction value LADi has not yet reached the retard limit,
Step 8308: Hedging.

In addition, in step 51 above, F, LADVi≦1mtR
If it is determined to be TD, this learning correction value IADVi has reached the delay limit, so in step 5113, the above RA
The learning correction (irll ADVi) for the cylinder #i stored in the predetermined address of M34 is set to the above-mentioned retardation limit correction value 1mtR.
Update with TD (LADVi←LmtRTD).

On the other hand, in step 5305 above, the average difference angular acceleration Δ(d
N/dt)8i is the fixed limit difference angular acceleration upper limit value Δ(
If it is determined that it is lower than dN/dt)u, <A (dN/
dt) Ai≦Δ(dN/dt)u), Step 83
Proceed to 06 and calculate the above average difference angular acceleration Δ(dN/dt)Ai
and the preset fixed limit difference angular acceleration lower limit value Δ(dN/
dt)L, and calculate the average difference angular acceleration Δ(dN/d
t) Ai is the fixed limit angular acceleration lower limit value Δ(LdN/d
t) If lower than L (Δ(dN/dt)Ai <Δ
(d14/dt)L), it is determined that the combustion condition of the cylinder #i is poor, and in step 5115, the cylinder #(7) science 1 correction value I stored at a predetermined address of the storage means is
ADVi (i=1.3, 2.4) at a predetermined crank angle C
(For example, update with the value corrected for the advance angle by C=1℃Δ) (
L ADVi4-L ADVi + Q).

Further, in step 5306, the average difference angular acceleration Δ
(dN/dt) Ai is the fixed limit difference angular acceleration lower limit Δ(d
If it is determined that it is within the range of N/dt)L (Δ(dN/dt)
)＾i≧Δ(dN/dt)L), since the above average difference angular acceleration Δ(dN/dt)8i is within the setting range, <l
(dN/dt)u >Δ(dN/dt)81≧Δ(dN
/dt)L), without updating the learning correction value LADVi, step 5308 is carried out.

Then, when the process proceeds from step 5113.3117 to step 5307, the average difference angular acceleration Δ(dN/dt)Ai(-1) calculated in step 5304 is reset (Δ(dN/dt)Ai ←φ). , in step 5308, the previous average differential angular velocity Δ(dN/dt)Ai(
-1) with the current differential angular acceleration Δ(dN/dt)Ai calculated in step 5304 or the value reset in step 5307, and the routine ends (1 (dN/dt)Ai( −1)←l (d
N/dt)Ai).

Note that the ignition timing control procedure is the same as in the first embodiment.

FIG. 11 shows the correlation between the engine speed and the engine angular acceleration. As mentioned above, by using the angular acceleration obtained by time-differentiating the engine speed, the time element is taken into consideration, so in this example, Accuracy is improved.

(Third Embodiment) The above figure and FIG. 13 show a third embodiment of the present invention,
The above figure is a functional block diagram of the control device, and FIG. 13 is a flowchart showing a combustion state detection procedure. Note that the means and steps having the same functions as those in the first embodiment are given the same reference numerals as in the first embodiment, and a description thereof will be omitted.

In this embodiment, the combustion state is estimated from the engine cycle instead of the engine rotation speed as in the first embodiment.

Reference numeral 62 in the above figure represents a combustion state detection means, which is comprised of a difference period calculation means 62a, an average difference period calculation means 62b1, a combustion state estimation means 62c, and an average difference period update means 62f.

In the difference cycle generation means 62a, when the idle operation is determined by the idle determination means 41e, the cycle calculation means 41c calculates the cycle f2, 38E- in the current routine,
The cycle f2.30LD calculated in the previous routine stored in a predetermined address of the storage means (RAM) 34 is read, and the cylinder discriminating means 41a reads the cycle f2.30LD calculated in the previous routine and uses the difference between the two cycles f'2.3NE and f2.30LD. The identified cylinder #i
The difference period Δfi (i=1.3.2゜4>) is 1H
H78 (, dft = child 2.3 NEW - child 2.30LD
).

Further, the difference period calculation means 62a calculates the period 1l11.
The periodic element 2.38E- calculated by the calculating means 41G is the periodic element 2.38E- calculated by the calculating means 41G.
Update 30LD (child 2.30LD←2,3NEW)
.

In the average difference period calculation means 62b, the difference period calculation means 6
The difference period Δt i of the cylinder #1 calculated in Step 2a and the previous average difference period Δt At ( -1), the current average difference period ΔAi of the cylinder #i is calculated from the weighted average.

This average difference period ΔfAi is obtained from the weighted average of the following equation.

lfA:= ((2'-1) XJfAi(-1)+
ΔI)/2' r: Weighting coefficient However, the initial average differential rotational speed ΔN8i is set to "0".

Note that this average rotational speed difference ΔfAt is calculated for each cylinder.

Calculations in the functional blocks described below are executed based on data for each cylinder.

The fixed lower limit value determining means 62d of the combustion state estimating means 62c calculates the average difference period ΔAi of the cylinder #1 calculated by the average difference period calculation means 62b and the preset fixed limit difference period lower limit value ΔC Compare.

Further, in the fixed upper limit value determining means 62e of the combustion state estimating means 62C, the fixed lower limit value determining means 62d determines that z-Ai≧Δ[, the above-mentioned average difference circumference)! 1Jt
1 The average difference period Δ of the cylinder #: calculated by the output means 62b
fAi and the preset fixed limit difference cycle upper limit value, 6fU
Compare with.

Note that the fixed limit difference cycle lower limit value Δ<i>[ and the above fixed limit difference cycle upper limit value Δfu are set based on the upper limit judgment value and lower limit judgment value of the indicated average effective pressure obtained from experiments etc. in advance. be. Furthermore, since the period Q is the reciprocal of the engine rotation speed, the upper limit and lower limit determinations are opposite to the case where the engine rotation speed is used.

In the average difference cycle updating means 62, the fixed lower limit value determining means 62d determines that ΔAi≧Δf, and the fixed upper limit value determining means 62e determines that Δ−1−Ai≦ΔU. In other words, the above average difference circumference O1] fAi
is within the fixed limit difference period range (Δf1−≦ΔfA
i≦ΔfLI>, or the learned value advance limit determining means 43 forming the learned value-limit determining means 43d of the ignition timing calculating means 43 determines that the learned correction value L8DVi is retarded from the advance limit correction value LmtADV. If it is determined that it is on the side (L
ADVi<LmtADV), or the learned value advance angle limit determining means 43e determines the learned correction value L ADV
When it is determined that i is on the advance side than the advance angle limit correction value L mtRTD (L ADVi > L mtRTD),
The previous average difference in frequency I (IlΔchi81−1
) is updated with the average difference period Δ child ^i calculated by the average difference period calculation means 62b (to Δ child 1 (-1) ← Δ child Ai
).

Further, the average difference cycle updating means 62f, the learned value retard limit determining means 43e1 or the learned value advance limit determining means 43f determine that l ADVi≦1mtRTD, Aruiha, and L ADVi≧L mtA DV. In this case, i should be reset to the average period Δ of the cylinder #1 calculated by the average difference period calculating means 62b.
), its reset average difference period 2fAi (i.e.,
φ), the previous average difference period ΔfAi (-1) of the cylinder #i stored in the address corresponding to the cylinder #i of the storage means (RAM) 34 is updated. Therefore, the average difference period Δf Ai (-1) of the cylinder is reset (Δもi(-1)←φ).

On the other hand, in the cylinder-specific learning correction value updating means 43Q in the ignition timing calculating means 43, when the fixed lower limit value determining means 62d of the combustion state estimating means 62c determines that dfAi<ΔfL, the combustion in the cylinder #i is not good. It is determined that the cylinder #i is too high, and the cylinder-specific learning correction value LADVi stored at a predetermined address in the storage means 34 corresponding to the cylinder #i discriminated by the cylinder discriminating means 41a is set at a predetermined crank angle C (for example, C
Update with a value delayed by -1℃A) (L ADV
i←LADVt −C).

Further, the cylinder-specific learning correction value updating means 43Q, the fixed upper limit value determining means 62e of the combustion state estimating means 62c,
If it is determined that dfAi>lfu, it is determined that combustion in the cylinder #i is poor, and the storage means corresponding to the cylinder #i determined by the cylinder determining means 41a (by cylinder stored at the address of RAM>34) Update the learning correction value L ADVi with a value that advances it by a predetermined crank angle r*c (for example, C=1℃A) (L ADVi4-L ADVi+
C).

Next, the procedure for estimating the combustion state during idling according to this embodiment will be explained according to the flowchart of FIG. 13. Note that this control program is executed for each cylinder separately.

When the cycles f2, 3 are calculated in step 5ios, the process advances to step 5401, and in step 5105, the cycle f2.3NEW calculated in this routine and the RAM 34
The relevant cylinder #1 calculated in the previous routine read out
Based on the difference between the periods of 2 and 30LD, the outer periphery 4f of the section where combustion stroke cylinder # is not doing work is determined by i (Δ
(-f2.3NEW-2.30LD), in step 5402, the previous cycle f2.3010 stored in a predetermined address of the RAM 34 is set in step 51.
Update with the current cycle f2.3NEW issued in 05 (f2.30LD+-f2,3NE匈).

Then, in step 5403, based on the outer period Δchii calculated in step 5401 and the previous average difference period of the cylinder #i calculated in the previous routine, dfAi (-1), the current average difference period is calculated. Δ%Ai is calculated from the weighted average of the weighting coefficient r (z child Δi←((2r-1)×Δf
81-1)+Δfi)/2).

Thereafter, in step 5404, the average difference period of the cylinder #i calculated in step 5403, 4-1-Ai,
Compare with the preset fixed limit outer period lower limit fL,
If it is determined that dfAi<ΔfL, J, that is, the average difference period Ai is less than the fixed limit outer period lower limit value ΔfL, it is determined that the combustion state of the cylinder #i is not good, and step 511
1, the learning correction value LADVi (i=1.3.2.4
) is updated with a value retarded by a predetermined crank angle C (for example, C=1°C) (L ADVI4-L ADVI
-C).

Then, in step 51 above, the learning correction value I ADVi for the cylinder #i calculated in step 5111 above is compared with the preset retard limit correction value L mtRT D, and L ADV+> l mtRT D (7) In this case, since the cylinder-specific learning correction value LADVi has not yet reached the retard limit, step 5407 is performed.

Mata, step 51 above, l ADVi≦L m
If it is determined that tRTD, this learning correction value L ADVi
has reached the retard limit, so in step 5113, the learned correction value 1-ADVi of the cylinder # stored in the predetermined address of R8M34 is set to the retard limit correction value LIIlt.
Update with RTD (L ADVi←LmtRTD).

On the other hand, in step 5404 above, the average outer circumference wJΔfAi
is determined to be greater than or equal to the fixed limit outer period lower limit value afL (,6fAi≧jf), the process advances to step 5405,
The above average difference period, jfAi, is compared with the preset fixed limit outer circumference upper limit Ofu, and the above average difference period Δ is calculated.
is larger than the above fixed limit outside upper limit value Δfu, <Af
A'+>lfu), it is determined that the combustion state of the cylinder #i is poor, and in step 5115, the learning correction value 1-A of the cylinder #i that is stored at a predetermined address in the RAM 34 is determined.
DVi (i=1.3, 2.4) is expressed as a predetermined crank angle C (
For example, update the value with the advance angle corrected by C=1°C△) (
LADVi←LΔDVi+C) Also, in the step $405 above, if it is determined that the average difference period ΔAi is less than the fixed limit outer period upper limit value ΔU (−CHAt≦ΔfU)
, since the above average difference period Δchi^i is within the setting range (Δ
child≦, dfAi≦, 4fu>, the above learning correction value LAD
Step 5407 is rejected without updating Vi.

Then, when the process proceeds from steps 3113 and 3117 to step 8406, the average difference period Δ<i>^i calculated in step 5403 is reset (Δ<i>Ai←φ).

Thereafter, in step 5407, the previous average difference period ΔfAi (-1) stored in the predetermined address of the RAM 34 is transferred to the current average difference period d calculated in step 5403 above.
1 or update it with the value reset in step 5406 above and end the routine (,6fAi(-1)-
Δ子＾＾).

In this embodiment, the engine rotation speed N NEW obtained by dividing Shu Tomoko 2 and 3 is not used, and the period f2.
Since the combustion state is estimated using No. 3, the burden on the operator due to the division n process in estimating the combustion state is reduced, and the calculation time for estimating the combustion state is shortened.

(Fourth embodiment) Figures 14 to 16 show a fourth embodiment of the present invention,
FIG. 14 is a functional block diagram of the tiIItIl device,
Figure 5 is a flowchart showing the combustion state detection procedure, No. 16.
The figure is a flowchart showing the ignition timing control procedure. Note that means having the same functions as those in the first embodiment and block diagrams are given the same reference numerals as those in the first embodiment, and explanations thereof will be omitted.

In this embodiment, the combustion state is estimated from the engine angular velocity instead of the engine rotational speed in the first embodiment.

Reference numeral 41a in FIG. 14 is an angular velocity calculating means in the sensor input data calculating means 41, and the θ1 (protrusion 15a) and θ2 determined by the crank pulse determining means 41b are
(Protrusion 15b)
Fllll t 1,2 was measured, and this elapsed time t1.2
Then, calculate the angular velocity ω1,2 from the included angle (θ1-02) (ω1,2 - d(θ1-θ2 /dt1,2
).

The angular velocity calculating means 41q also calculates the θ2 (protrusion 15b) determined by the crank pulse determining means 41b.
The elapsed time t2.3 between the crank pulses that detect and θ3 (protrusion 15C) is measured, and this elapsed time t2
．． 3 and the pinch angle (θ2-θ3), the angular velocity ω2,3
Calculate (ω2,3 = d(θ2-θ3/dt2,
3).

Further, the engine speed calculation means 41d calculates the engine speed NNE- based on the angular speed ω1゜2 output from the angular speed calculation means 41QT:0 (N1.2 -6
0ω1,2/(2π)).

Further, the ignition time setting means 43i of the ignition first period calculation means 43
Now, the relevant cylinder #i set by the ignition timing setting means 43h
ignition timing (angle) θIG and the angular velocity calculation means 41
The ignition time ADV is set from the angular velocity ω1,2 determined at g (ADV-θrG/ω1.2).

On the other hand, reference numeral 72 denotes a combustion state detection means, which includes a difference angular velocity calculation means 72a, an average difference angular velocity calculation means 72b, a combustion state estimation means 72C1, and an average difference angular velocity update means 72f.

The difference angular velocity calculating means 72a uses the above-mentioned idling judgment). When the separate means 41e judges that the engine is idling, the engine angular speed calculating means 41q calculates the angular velocities ω2, 3NE- calculated in the current routine and the storage means (RAM>3).
Read the predetermined address of 4 and the stored angular velocity ω2, 30LD calculated in the previous routine, and set both angular velocities ω2.
, 3NEW, ω2, 3010, the cylinder discrimination means 41a discriminates the cylinder's differential angular velocity Δωi (i=
1.3,2.4> (Aωi−ω2,3NEW
-ω2,30LD).

Further, the difference angular velocity calculation means 72a updates the angular velocity ω2, 3010 stored at a predetermined address of the storage means (RAM) 34 with the angular velocity ω2, 3NEW calculated by the angular velocity calculation means 410 (ω230LO←ω2, 3
NEllI).

The average angular velocity difference calculation means 72b calculates the difference angular velocity Δωi of the cylinder #i calculated by the difference angular velocity calculation means 62a,
The weighted average force 1 of the previous average difference angular velocity ΔωAi (-1) of the cylinder #i calculated in the previous routine stored in a predetermined address of the storage means (RAM) 34 is the current average of the cylinder #1. The difference angular velocity ΔωAi is calculated.

This average difference angular velocity ΔωAi is obtained from the weighted average of the following equation.

dωAi-((2-1) XaωAi(-1)+Δωi
)/2' r: Weighting coefficient However, the initial average difference angular velocity ΔωAi is 110 I+
shall be.

Note that this average differential angular velocity ΔωAi is calculated for each cylinder.

Calculations in the functional blocks described below are executed based on data for each cylinder.

The fixed upper limit value determining means 72d of the combustion state estimating means 72G compares the average differential angular velocity Zω81 of the cylinder #i calculated by the average differential angular velocity calculating means 72b with a preset fixed limit differential angular velocity upper limit value ΔωAυ. do.

Further, in the fixed lower limit value determining means 72e of the combustion state estimating means 72C, the fixed upper limit value determining means 72d determines that Ja
) When it is determined that Ai≦ΔωU, the average differential angular velocity P3Δ of the cylinder #i calculated by the average differential angular velocity calculation means 72b
ωAi and the preset fixed limit difference angular velocity lower limit value Δω[
Compare with.

Note that the fixed limit difference angular velocity upper limit value ΔωU and the fixed limit difference angular velocity lower limit value 2ωL are set based on the upper limit judgment value and lower limit judgment value of the indicated average effective pressure, which are determined in advance through experiments or the like.

In the average difference angular velocity updating means 72f, when the fixed upper limit value determining means 72d determines that ΔωAi≦ΔωU and the fixed lower limit value determining means 72e determines that ΔωAi≧Δω[, that is, the average difference angular velocity 2ω If ^1 is within the range of fixed limit difference angular velocity (7!llωU≧Δω
Ai≧Δω[), or the learning value advance limit determining means 43f constituting the learned value limit determining means 43d of the ignition timing calculating means 43 determines that the learned correction value LADVi is slower than the advance limit correction value LmtADV. If it is determined that it is on the corner side (L ADVi < L mtADV), or the learned value retard limit determining means 43e determines the learned correction value L AD
When it is determined that Vi is on the advance side than the retard limit correction value 1mtRTD (LADV>l-mtRTD), the cylinder determining means 41ar selects a predetermined address of the storage means (RAM) 34 corresponding to the cylinder #i determined by the cylinder determining means 41ar. The previous average difference angular velocity ΔωAi (-1) of the relevant cylinder # stored in is equal to the average difference angular velocity Δω calculated by the average difference angular velocity updating means 72b.
Update with Ai (ΔωAi(-1)←ΔωAi).

Further, in the average difference angular velocity updating means 72-f-, the L learned value retard limit determining means 43e or the learned value advance limit determining means 43f determines that IAovr≦L111tRT.
D, or when it is determined that 1ADVi≧L +ntA D Angular velocity ΔωA
i (i.e., φ), the above storage means <8M in 1) 34
The previous average differential angular velocity 2ωAi (-1) of the cylinder #i stored in the address corresponding to the cylinder #i is updated. Therefore, the average differential angular velocity Δω81(-1
) is reset〈ΔωA+(-1)←φ).

On the other hand, in the cylinder-specific learning correction value updating means 43q in the ignition timing calculating means 43, the fixed upper limit value determining means 72d of the combustion state estimating means 72c determines that Aω8>Δω^i>zω
If it is determined that the combustion is too good for the cylinder #i, it is determined that the combustion of the cylinder #i is too good, and the cylinder-specific learning correction value IADVi stored at a predetermined address of the storage means 34 corresponding to the cylinder #i determined by the cylinder determining means 41a is determined. is updated with a value retarded by a predetermined crank angle C (for example, C=1°C
DVi←l ADVi+ C).

Further, in the cylinder-specific learned correction value updating means 43q, when the fixed lower limit value determining means b2e of the combustion state estimating means 62G determines that ωAi<, 4ωL, the cylinder #i
It is determined that combustion is poor in the cylinder #i, and the cylinder-specific learning correction value LADVi stored in the address of the storage means (RAM>34) corresponding to the cylinder #i discriminated by the cylinder discriminating means 41a is set at a predetermined crank angle C (for example, Update with a value advanced by C=1℃A) (L ADVi←l ADVi+ C
).

Next, the procedure for determining the combustion state during idling according to this embodiment will be explained according to the flowchart of FIG.

After determining the crank pulse in step 5104, step 5
soi, BTDCθ determined in step 5104 above
2.3 The elapsed time between the crank pulses for detecting θ2 and θ3 and the angle between θ2 and θ3 (θ2-0
3) Calculate the angular velocity ω2,3 from (ω2,3
←d(02-θ3)/dt2,3).

After that, in step 5502, the engine angular velocity ω2,3N[ of the current routine calculated in step 5501 above]
From the difference between the engine angular speed ω2.30LD of the cylinder #1 and the engine angular speed ω2.30LD of the cylinder #1 calculated in the previous routine, the difference angular speed It! Δωi
Calculate Δωi←ω2,3NEW−ω2,3010)
, in step 5503, the previous engine angular velocity ω2,30LD stored in a predetermined address of the RAM 34 is changed to the current engine angular velocity ω calculated in step 5soi above.
Update with 2,3NE oath (ω2,30LD←ω2,3N
EW).

Then, in step 5504, the current average differential angular velocity ΔωAi is calculated based on the differential angular velocity Δωi calculated in step 5502 and the previous average differential angular velocity ΔωAi (-1) of the cylinder #i calculated in the previous routine. Obtained from the weighted average of the coefficient r (Δω^i←((2r-1)x, j
ωAi(-1)+dωi)/2').

Thereafter, in step 5505, the average differential angular velocity ΔωAi of the cylinder #i calculated in step 5504 is compared with a preset fixed limit differential angular velocity upper limit value ΔωU, and
If it is determined that ω^i>Δωu1, that is, the average differential angular velocity ΔωAi is larger than the fixed limit differential angular velocity upper limit value ΔωU, it is determined that the combustion state of the cylinder #i is not good, and in step 5111, the data is stored at a predetermined address in the RAM 34. The stored learning correction value LADVi (i=1.3
．． 2.4) at a predetermined crank angle C (for example, C=1°C)
A) is updated with the retarded value (L ADVi+-L A
DVi-C).

Then, in step 51 above, the learning correction value LADVi for the cylinder #i calculated in step 5111 above is compared with the preset retard limit correction value LmtRTD, and L
ADVi> L mtRT D (1) If 8, cylinder-specific learning correction value is determined and ADV i has not yet reached the delay limit, so step 3508 is proceeded to.

Mata, Stellaf 51 above, L ADVi≦L 1
If it is determined that it is ltRTD, this learning correction value I ADV
Since i has reached the retard limit, in step 5113,
The learning correction value 1-ADCi of the relevant cylinder # stored in the predetermined address of the RAM 34 is set as the retardation limit correction value L mt.
It updates with RTD (lADVi←LmtRTD) and proceeds to step 5507.

On the other hand, in step 5505 above, the average difference angular velocity Δω^i
is lower than the fixed limit differential angular velocity upper limit value ΔωU (ΔωAi≦Δω0), the process advances to step 3506, and the average differential angular velocity r! 3ΔωAi and a preset fixed limit difference angular velocity lower limit value Δω are compared, and if the average difference angular velocity Δω^i is lower than the fixed limit difference angular velocity lower limit value Δω[(ΔωAi<ΔωL), the corresponding cylinder #1 It is determined that the combustion condition of the RAM 34 is poor, and in step 5115,
The learning correction value LADVi (i=1°3.2.4) for the cylinder #i stored in a predetermined address of is advanced by a predetermined crank angle C (for example, C-1℃A). Update (LADVi←LADVi+C).

Further, in step 55 (16), the average difference angular velocity Δ
If ω^1 is determined to be greater than or equal to the fixed limit difference angular velocity lower limit value 2ωL (Aω^i≧Δω[), the above average difference angular velocity ΔωAi
is within the setting range (ΔωU≧Δω＾i≧Δω[)
, jumps to step 8508 without updating the learning correction value LADVi.

Then, step 5113 or step 5
When proceeding from step 117 to step 5507, the above step 5
In step 504, the average differential angular velocity ΔωAi produced by the whale is reset (ΔωAi←φ).

Thereafter, in step 8508, the previous average differential angular velocity Δω81 (-1) stored in a predetermined address of the RAM 34 is converted to the current average differential angular velocity 7ω calculated in step 5504 above.
^i, or update it with the value reset in step 5507 above, and end the routine (to Δω8 (-1
)←To Δω8i.

On the other hand, in the ignition timing control procedure, step 3203
After determining the crank pulse in step 5250, the elapsed time t1,2 between the crank pulses for detecting the BTDC θ1 θ2 determined in step 5203, and the above θ
From the included angle (θ1-θ2) of 1 and θ2, the angular velocity ω1
,2 (ω1,2 ←d(θ1−θ2
)/dt1.2>.

Next, in step 5251, the engine rotation speed N is determined based on the angular velocity ω1,2 calculated in step 3250 above.
Calculate 1.2 ( N 1,2 ← (60/2π)
×ωabove).

In addition, in step 8206, the step 52 described above,
Alternatively, the ignition timing OEG calculated in step 5214
and the angular velocity ω1,2 calculated in step 3250 above.
Set the ignition poetry ADV from (△D■←θrG/
ω1.2).

According to this embodiment, since the combustion state is estimated using the angular velocity ω2.3 as a substitute for the engine rotational speed NNE-, the calculation time for estimating the combustion state is shortened compared to the first embodiment.

(Other Embodiments) In each of the above-mentioned embodiments, an example using a 4-cycle 4-cylinder engine has been described, but any combustion stroke that does not overlap may be used. Cylinder engine, 4 cycle 3
It can also be applied to cylinder engines, 2-stroke single-cylinder engines, and 2-stroke 2-cylinder engines.

[Effects of the Invention] As explained above, according to the present invention, the following effects are achieved.

(1) According to the engine combustion state detection device described in claims 1, 2, and 3.4, a difference rotational speed or a difference angular acceleration having a correlation with the combustion state of each cylinder, or
Since the outer period or the average value of the differential angular velocity is compared with the fixed limit value, the quality of one combustion state can be judged as an absolute quantity, so the combustion state of each cylinder can be accurately grasped.

In addition, since the combustion state is estimated based on the output signals of the sensors installed in the engine, there are no parts costs and it can be immediately applied to existing engines, making it highly versatile. There is.

(2) According to the engine ignition timing control device recited in claim 5.6.7.8, in addition to the above-mentioned effects, the ignition timing can be adjusted accurately for each cylinder in accordance with the combustion state of each cylinder. In particular, the idle speed can be stabilized, and noise and vibration can be significantly reduced.

[Brief explanation of the drawing]

1 to 8 show a first embodiment of the present invention;
Figure 2 is a conceptual diagram of the engine control system; Figure 3 is a front view of the crank rotor and crank angle sensor; Figure 4 is a front view of the cam rotor and cam angle sensor; The figure is a conceptual diagram of the basic ignition timing map, and Figure 6 shows the internal pressure fluctuations, crank pulses, cam pulses, and
7 is a flowchart showing the combustion state estimation procedure, FIG. 8 is a flowchart showing the ignition timing control procedure, and FIGS. 9 to 11 are the second flowchart of the present invention. 9 is a functional block diagram of the control device, FIG. 10 is a flowchart showing the combustion state detection procedure, FIG. 11 is a time chart of crank pulses, cam pulses, engine speed, and angular acceleration, and the above-mentioned 13 and 13 show a third embodiment of the present invention, the above figure is a functional block diagram of the control device, FIG. 13 is a flowchart of the combustion state detection procedure, and FIGS. 14 to 16 are the third embodiment of the present invention. FIG. 14 is a functional block diagram of the control device, FIG. 15 is a flowchart showing a combustion state detection procedure, and FIG. 16 is a flowchart showing an ignition timing control procedure. 41a...Difference rotational speed locking means, 42b...Average difference rotational speed calculation means, 42c, 52d, 62c, 72C.
... Combustion state estimating means, 43a... Engine load setting means, 43b... Basic ignition timing setting means, 43q...
・Cylinder-specific learning correction value update means, /13h...at ignition +
! II setting means, 52b... difference angular acceleration calculation means, 5
2C... Average difference angular acceleration 91 output means, 62a... Outer period 9 output means, 62b... Average outer circumference m calculation means, 7
2a...Difference angular velocity calculation means, 72b...Average difference angular velocity calculation means. 387-

Claims (8)

[Claims] (1) Compare the engine rotation speed in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder with the engine rotation speed in the section where no work is being done by combustion in the previous combustion stroke. a rotational speed difference calculation means for calculating the rotational speed difference of the cylinder, the current rotational speed difference of the cylinder calculated by the rotational speed difference calculation means, and the previous average rotational speed difference of the cylinder of the cylinder. An average difference rotational speed calculation means for calculating an average difference rotational speed compares the average difference rotational speed of the cylinder calculated by the average difference rotational speed calculation means with a preset fixed limit difference rotational speed of the cylinder. A combustion state detection device for an engine, comprising a combustion state estimating means for estimating a combustion state. (2) Compare the engine angular acceleration in the section where no work is being done due to combustion between the current combustion stroke cylinder and the next combustion stroke cylinder with the engine angular acceleration in the section where no work is being done due to the previous combustion. a difference angular acceleration calculation means for calculating the difference angular acceleration of the cylinder, the current difference angular acceleration of the cylinder calculated by the difference angular acceleration calculation means, and the previous average difference angular acceleration of the cylinder. An average difference angular acceleration calculation means for calculating an average difference angular acceleration compares the average difference angular acceleration of the cylinder calculated by the average difference angular acceleration calculation means with a preset fixed limit difference angular acceleration of the cylinder. A combustion state detection device for an engine, comprising a combustion state estimating means for estimating a combustion state. (3) Compare the engine cycle in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder with the engine cycle in the section where no work is being done by combustion in the previous combustion stroke. a difference period calculation means for calculating the difference period of the cylinder; and an average for calculating the average difference period of the cylinder from the current difference period of the cylinder calculated by the difference period calculation means and the previous average difference period of the cylinder. A difference period calculation means; and a combustion state estimation means for estimating the combustion state of the cylinder by comparing the average difference period of the cylinder calculated by the average difference period calculation means with a fixed limit difference period set in advance. An engine combustion state detection device characterized by: (4) The engine angular velocity in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder,
difference angular velocity calculation means for calculating the differential angular velocity of the relevant cylinder by comparing the engine angular velocity in a section where no work is being done due to previous combustion; average difference angular velocity calculation means for calculating the average difference angular velocity of the cylinder from the previous average difference angular velocity of the cylinder; the average difference angular velocity of the cylinder calculated by the average difference angular velocity calculation means; and a preset fixed limit difference angular velocity. What is claimed is: 1. A combustion state detection device for an engine, comprising: combustion state estimating means for estimating the combustion state of the cylinder by comparing the combustion state of the cylinder. (5) An engine load setting means for setting the engine load based on the engine speed and intake air amount, and setting basic ignition timing for each cylinder based on the engine load set by the engine load setting means and the engine speed. The basic ignition timing setting means, the engine rotational speed in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder, and the engine rotational speed in the section where no work is being done due to the previous combustion. a difference rotational speed calculation means that calculates a difference rotational speed of the cylinder by comparing the difference rotational speed of the cylinder, the current difference rotational speed of the cylinder calculated by the difference rotational speed calculation means, and the previous average difference rotational speed of the cylinder. an average differential rotational speed calculating means for calculating an average differential rotational speed of the cylinder from the above, and a comparison between the average differential rotational speed of the cylinder calculated by the average differential rotational speed calculation means and a preset fixed limit differential rotational speed. combustion state estimating means for estimating the combustion state of the cylinder; and when the combustion state estimating means determines that the average differential rotational speed is lower than the fixed limit differential rotational speed, advancing the ignition timing by a set angle; and cylinder-specific learning correction value updating means for updating the learning correction value of the cylinder with a correction value that retards the ignition timing by a set angle when it is determined that the average differential rotational speed is higher than the fixed limit differential rotational speed; ignition timing setting means for setting the ignition timing of the cylinder by correcting the basic ignition timing set by the basic ignition timing setting means using the learning correction value updated by the cylinder-specific learning correction value updating means. Ignition timing control device for engines. (6) An engine load setting means for setting the engine load based on the engine speed and intake air amount, and setting basic ignition timing for each cylinder based on the engine load set by the engine load setting means and the engine speed. The basic ignition timing setting means, the engine angular acceleration in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder, and the engine angular acceleration in the section where no work is being done due to the previous combustion. a difference angular acceleration calculation means that calculates a difference angular acceleration of the cylinder by comparing the difference angular acceleration of the cylinder, the current difference angular acceleration of the cylinder calculated by the difference angular acceleration calculation means, and the previous average difference angular acceleration of the cylinder. an average difference angular acceleration calculation means for calculating an average difference angular acceleration of the cylinder from a combustion state estimating means for estimating the combustion state of the cylinder, and when the combustion state estimating means determines that the average difference angular acceleration is lower than the fixed limit difference angular acceleration, advancing the ignition timing by a set angle; and cylinder-specific learning correction value updating means for updating the learning correction value for the cylinder with a correction value that retards the ignition timing by a set angle when it is determined that the average differential angular acceleration is higher than the fixed limit differential angular acceleration; ignition timing setting means for setting the ignition timing of the cylinder by correcting the basic ignition timing set by the basic ignition timing setting means using the learning correction value updated by the cylinder-specific learning correction value updating means. Ignition timing control device for engines. (7) An engine load setting means for setting the engine load based on the engine speed and intake air amount, and setting basic ignition timing for each cylinder based on the engine load set by the engine load setting means and the engine speed. The basic ignition timing setting means, the engine cycle in the section where no work is being done by combustion between the current combustion stroke cylinder and the next combustion stroke cylinder, and the engine cycle in the section where no work is being done due to the previous combustion. A difference period calculation means for calculating a difference period of the cylinder by comparing the current difference period of the cylinder calculated by the difference period calculation means and the average difference period of the cylinder from the previous average difference period of the cylinder. an average difference period calculation means for calculating the average difference period, and a combustion state estimation for estimating the combustion state of the cylinder by comparing the average difference period of the cylinder calculated by the average difference period calculation means with a fixed limit difference period set in advance. means, if the combustion state estimating means determines that the average difference period is lower than the fixed limit difference period, the ignition timing is retarded by a set angle, and if the average difference period is higher than the fixed limit difference period; If determined, cylinder-specific learning correction value updating means updates the learning correction value for the cylinder with a correction value that advances the ignition timing by a set angle; 1. An ignition timing control device for an engine, comprising ignition timing setting means for correcting the ignition timing of the cylinder by correcting it using the learning correction value updated by the learning correction value updating means. (8) An engine load setting means for setting the engine load based on the engine speed and intake air amount, and setting basic ignition timing for each cylinder based on the engine load set by the engine load setting means and the engine speed. The basic ignition timing setting means, the engine angular speed in the section where no work is being done due to combustion between the current combustion stroke cylinder and the next combustion stroke cylinder, and the engine angular speed in the section where no work is being done due to the previous combustion. A difference angular velocity calculation means for calculating a difference angular velocity of the cylinder by comparison, and an average difference angular velocity of the cylinder based on the current difference angular velocity of the cylinder calculated by the difference angular velocity calculation means and the previous average difference angular velocity of the cylinder. and a combustion state estimation unit that estimates the combustion state of the cylinder by comparing the average difference angular velocity of the cylinder calculated by the average difference angular velocity calculation means with a preset fixed limit difference angular velocity. means, if the combustion state estimating means determines that the average differential angular velocity is lower than the fixed limit differential angular velocity, the ignition timing is advanced by a set angle, and if the average differential angular velocity is higher than the fixed limit differential angular velocity, If determined, cylinder-specific learning correction value updating means updates the learning correction value of the cylinder with a correction value that retards the ignition timing by a set angle; 1. An ignition timing control device for an engine, comprising ignition timing setting means for correcting the ignition timing of the cylinder by correcting it using the learning correction value updated by the learning correction value updating means.