JPH0666238A - Internal combustion engine control unit - Google Patents

Abstract

PURPOSE:To prevent hunting that could be caused by the feedback control of ignition timing, which is performed in order to control the speed of an internal combustion engine to a desired value, by canceling the feedback control should the misfire of the internal combustion engine be detected according to crank angle. CONSTITUTION:A crank angle detection means M2 produces a reference period signal Ttheta synchronously with rotation of an engine M1, the reference period signal Ttheta indicating a crank-angle position corresponding to ignition timing. A misfire detecting portion M3 detects the misfire of the engine M1 according to the ratio of time of a pulse period before the crank-angle position to that after it. An ignition-timing control portion computes the ignition timing from the reference period signal Ttheta. An ignition-timing feedback control portion controls the speed of the engine M1 to a desired value. In this case, the ignition- timing control portion makes the ignition-timing feedback control portion inoperative if the misfire detecting portion M3 detects a misfire. Hunting, which could be caused by the ignition-timing feedback control performed when a misfire is detected, is therefore prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine controller for controlling ignition timing based on a reference period signal synchronized with the rotation of an internal combustion engine and detecting a misfire. The present invention relates to an internal combustion engine control device that prevents the above.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a general internal combustion engine controller described in, for example, Japanese Patent Application No. 2-414000. In the figure, M1 is an engine which is a main body of an internal combustion engine, M2 is a crank angle detecting means for generating a pulse-shaped reference period signal Tθ corresponding to a crank angle position in synchronization with rotation of the engine M1, and M3 is a reference period signal Tθ. Is a misfire detection unit that detects a misfire based on the time ratio of the predetermined section or the acceleration of the time ratio.

The crank angle position corresponds to the ignition timing of the internal combustion engine and is used as a control reference for the ignition timing.
Used to detect engine speed. Further, as the predetermined section used for the calculation of the time ratio, for example, a pulse cycle section before and after the top dead center (TDC) is selected.

The misfire detecting section M3 has a time detecting means and a misfire determining means, and is included in an ECU (described later) which is a microcomputer for controlling ignition. The ECU
An ignition timing control unit that controls the ignition timing based on the reference period signal Tθ, an ignition timing feedback control unit that controls the rotational speed of the internal combustion engine to a target value, and a pulse period before and after the crank angle position are provided. A misfire detection unit M3 that determines misfire of the internal combustion engine based on the time ratio is provided, and ignition control during steady operation is performed based on the reference cycle signal Tθ, and the rotational speed is made to match the target rotational speed. It suppresses fluctuations.

FIG. 3 is a block diagram embodying FIG.
Is an engine (corresponding to M1) composed of # 1 cylinder 2 to # 4 cylinder 5, and 6 is a crank angle sensor (corresponding to M2) connected to the crankshaft or camshaft of the engine 1. 7
Is an ECU that takes in the reference period signal Tθ, and includes the function of the misfire detection unit M3.

The ECU 7 comprises an input interface 8 for taking in the reference period signal Tθ and a microcomputer 9. The microcomputer 9 counts up every fixed time clock with a memory 10 for storing various processing procedures and control information. A timer 11 for controlling the ignition timing and a CPU 12 for executing ignition timing calculation control, misfire detection calculation processing, ignition timing feedback control, and the like.

FIG. 4 is a timing chart showing various operating conditions with respect to each crank angle position of the reference cycle signal Tθ. (A) shows a change in cylinder pressure, (b) shows a waveform of the reference cycle signal Tθ, and (c) shows Change in angular velocity, (d) is change in time ratio for each predetermined crank angle section.

In FIG. 4 (a), TDC is the top dead center, BD
C is the bottom dead center, the solid line is the cylinder pressure of cylinder # 1, and the broken line is #
The in-cylinder pressure of the three cylinders, the one-dot chain line indicates the in-cylinder pressure of the # 2 cylinder, and the two-dot chain line indicates the in-cylinder pressure of the # 4 cylinder. #Cylinder pressure (solid line)
In the above, the waveform centered on the crank angle of 360 ° is normal combustion, and the waveform centered on the crank angle of 1080 ° is the waveform in the misfire state which occurs when ignition failure or the air-fuel ratio is inappropriate.

In FIG. 4B, the reference period signal Tθ is a pulse having a constant crank angle period, and TL is an H level section.
(Crank angle 70 °), TU is L level section (crank angle 110 °), T is one cycle of each pulse (crank angle 1
80 °) time. The falling timing of each pulse of the reference cycle signal Tθ corresponds to the ignition timing of each cylinder 2-5.

In FIG. 4C, the angular velocity increases in response to the torque increase due to the explosion process of each cylinder and decreases in response to the compression process. Here, as shown after the crank angle of 1080 °, when misfire occurs, the torque increase due to the explosion process cannot be obtained, so the angular velocity decreases and continues to decrease until the next explosion of the # 3 cylinder occurs. Therefore, the misfire detection unit M3 can determine the misfire from the time ratio of the predetermined crank angle section or the variation amount of the angular velocity.

Next, the misfire detection operation of the conventional internal combustion engine control system will be described with reference to the flow chart of FIG. 5 together with FIGS. First, it is determined whether the time ratio of crank angle sections before and after TDC is larger than a predetermined value.
(Step S1), if the time ratio> the predetermined value, it is determined that there is a misfire
(Step S2) If the time ratio is less than or equal to the predetermined value, it is determined to be normal (Step S3).

The time ratio used in the determination step S1 is
For example, it is a value corresponding to the angular acceleration α, the current value of the time TL and TU for each predetermined section is TL (i) and TU (i), the previous value is TL (i-1) and TU (i-1), Cycle T (= TL +
If the previous value of TU) is T (i-1), it is expressed as follows.

Α = [TL (i) / {T (i−1)} ³ ] × {TU (i) / TL (i) −TU (i−1) / TL (i−1)} (1 )

From the equation (1), the TU / T decreases as the angular velocity decreases.
Since the value of L increases, it can be seen that the time ratio (the angular acceleration equivalent value α) increases according to the decrease amount of the angular velocity. Therefore, when the time ratio exceeds a predetermined value, abnormal angular velocity (torque) decrease, that is, misfire is determined.

Further, as described above, in the internal combustion engine control device, the ignition timing feedback is performed regardless of the misfire determination result. FIG. 6 is a waveform diagram showing a temporal change in the engine speed, and shows a state in which the engine speed fluctuation is suppressed by the ignition timing feedback.

FIG. 7 is a characteristic diagram showing the engine generated torque with respect to the ignition control timing. The ignition timing is set to the top dead center TD.
It can be seen that the torque becomes maximum when the crank angle is set to 12 ° in front of C (B12 °).

Therefore, when the rotational speed becomes higher than the target value, the ECU 7 controls the ignition timing to be on the retard side of, for example, B12 ° to reduce the torque so that the rotational speed becomes lower than the target value. If it also becomes low, the ignition timing is controlled so as to be on the advance side in the vicinity of B12 °, and the torque is increased.

However, if the ignition timing feedback control is performed at the time of misfire determination, fluctuations in the rotational speed due to misfire are attempted to be suppressed by the advance control of the ignition timing, which causes hunting to the contrary. Because the reference period signal T
This is because the current rotation speed fluctuation is detected based on the cycle fluctuation of θ.

For example, as shown in the waveform diagram of the engine speed of FIG. 8, the time t at which the engine speed is actually higher than the target value.
If the occurrence of misfire is determined in 1, the ECU 7
Since the cycle of the reference cycle signal Tθ becomes long, it is determined that the current rotation speed is low, and the ignition timing feedback control is performed in the direction of further increasing the rotation speed.

When the occurrence of misfire is no longer determined, the ignition timing feedback control is performed in the direction of decreasing the rotational speed, and when the occurrence of misfire is determined again, the ignition timing feedback control is performed in the direction of increasing the rotational speed. By repeating this, as shown in FIG. 8, a hunting state results.

[0021]

As described above, the conventional internal combustion engine control device performs the ignition timing feedback control regardless of whether or not there is a misfire, so that there is a problem that hunting of the number of revolutions occurs at the time of misfire determination. was there.

The present invention has been made in order to solve the above problems, and an object thereof is to obtain an internal combustion engine control device which prevents hunting due to ignition timing feedback control at the time of misfire determination.

[0023]

The internal combustion engine control apparatus according to the present invention is such that the ignition timing feedback control section is invalidated when the misfire detection section determines a misfire.

[0024]

In the present invention, the ignition timing feedback control is normally performed, and the ignition timing feedback is not performed when the misfire is determined.

[0025]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a flow chart showing the operation of the first embodiment of the present invention. The configuration of the internal combustion engine controller according to the present invention, and the normal misfire determination operation and ignition timing feedback control operation are the same as those described above, and are as shown in FIGS.

In FIG. 1, first, it is determined whether or not a misfire has occurred (step S10). At this time, it is assumed that the misfire determination is performed in advance according to the routine of FIG. if,
If there is no misfire, the ignition timing control unit in the ECU 7
The ignition timing feedback control unit is enabled, the ignition timing feedback is performed as usual (step S11), and the process ends.

On the other hand, if it is determined in step S10 that a misfire has occurred, the ignition timing control section invalidates the ignition timing feedback control section and terminates the processing without executing the ignition timing feedback (step S11). This prevents erroneous determination of the engine speed and prevents hunting due to ignition timing feedback control.

[0028]

As described above, according to the present invention, the ignition timing feedback control unit is disabled when the misfire detection unit determines the misfire. Therefore, the internal combustion engine prevents hunting due to the ignition timing feedback control. The engine control device can be obtained.

[Brief description of drawings]

FIG. 1 is a flowchart showing the operation of Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a configuration of a general internal combustion engine control device.

FIG. 3 is a configuration diagram specifically showing the internal combustion engine control device of FIG. 2.

FIG. 4 is a timing chart showing the operation of a general internal combustion engine controller.

FIG. 5 is a flowchart showing a misfire detection operation of a general internal combustion engine controller.

FIG. 6 is a waveform diagram showing a variation of a general engine speed.

FIG. 7 is a characteristic diagram showing a general relationship between ignition timing and torque.

FIG. 8 is a waveform diagram showing hunting of engine speed by a conventional internal combustion engine control device.

[Explanation of reference signs] M1, 1 engine M2, 6 crank angle detecting means M3 misfire detecting section 7 ECU Tθ reference cycle signal TL, TU pulse section S11 ignition timing feedback step

Claims (1)

[Claims] 1. A crank angle detection means for generating a reference cycle signal indicating a crank angle position corresponding to an ignition timing of the internal combustion engine in synchronization with the rotation of the internal combustion engine, and the ignition timing based on the reference cycle signal. And an ignition timing feedback control unit for controlling the rotation speed of the internal combustion engine to a target value, and the internal combustion engine based on a time ratio corresponding to pulse cycles before and after the crank angle position. In an internal combustion engine control device including: a misfire detection unit that determines misfire, the ignition timing control unit disables the ignition timing feedback control unit when the misfire detection unit determines misfire. A characteristic internal combustion engine control device.