JPH04314967A - Electronic controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent an abnormal delayed angle due to sharp acceleration in cases where the aimed ignition timing is set to a delayed angle side in comparison with SGTT. CONSTITUTION:When an aimed ignition timing is set to a delayed angle side in comparison with SGTT, the lapse time +alpha from SGTT to the aimed ignition timing is determined as limit time T0, and it is confirmed if an ignition signal is generated after the lapse of the limit time T0 from the actual detection of SGTT, and if no ignition signal is generated, an ignition signal is forcedly generated.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention detects a first crank angle position SGTT and a second crank angle position SGTL on the advanced side of this in an internal combustion engine, and calculates and sets a target ignition timing for each SGTL. This invention relates to an electronic control device for an internal combustion engine.

0002

2. Description of the Related Art Conventionally, this type of electronic control device uses a crank angle sensor disposed in an internal combustion engine (hereinafter simply referred to as the engine) to detect a 4-cylinder internal combustion engine, as shown in FIG. Obtaining crank angle signal. That is, every time the crankshaft rotates 1/2 (180 degrees), a pulsed electrical signal as shown in FIG. 6 is obtained from the crank angle sensor. P1 shown in the figure is the detection point of the first crank angular position SGTT, and P2, which is more advanced than this, is the detection point of the second crank angular position SGTL. In addition, in the same figure, P3 is the top dead center of the engine, and in this example, S
GTT is set at 6 degrees before top dead center, and SGTL is set at 76 degrees before top dead center. Then, the above-mentioned electronic control device measures the SGTL detection period T1 from this crank angle signal,
Based on the engine speed determined from this period T1 and the intake air amount determined from the signal from the air flow sensor, the ignition timing optimal for the operating condition is set as the target ignition timing.
Calculate and set for each TL. FIG. 7(a) shows the above-mentioned crank angle signal, and FIG. 7(b) shows the ignition signal. In this example,
This shows a case where the target ignition timing is set to be more advanced than SGTT, and ignition is performed when the elapsed time from SGTL reaches the set timing t1 responsive to the target ignition timing. If the SGTT detection timing t2 suddenly moves to t2' due to rapid acceleration, as shown in FIG. There is a risk of a misfire. Therefore, conventionally, when the target ignition timing is set to the advanced side of the SGTT, when sudden acceleration occurs, the ignition is stopped at the SGTT detection timing t2' as shown in FIG. This is done to ensure that the ignition timing does not become abnormally retarded. An example of this type of electronic control device is ``Electronic Ignition Control Device for Internal Combustion Engines'' disclosed in Japanese Patent Publication No. 58-51155.

0003

[Problems to be Solved by the Invention] However, in such a conventional electronic control device for an internal combustion engine, it is difficult to prevent abnormal ignition retardation due to sudden acceleration when the target ignition timing is set to the advanced side of the SGTT. However, no measures have been taken to prevent abnormal ignition retardation due to sudden acceleration when the target ignition timing is set to the retard side than the SGTT. That is, it is now assumed that ignition is performed at timing t4 on the retarded side of SGTT, as shown in FIGS. 8(a) and 8(b) showing the crank angle signal and ignition signal. Here, due to rapid acceleration, SGT
As shown in the figure (c), the detection timing t3 of T is t
If it suddenly moves to 3', the next ignition will be performed at the same timing as t4, as shown in FIG.

0004

[Means for Solving the Problems] The present invention has been made to solve the above problems, and in the above-mentioned electronic control device, when the target ignition timing is set to the retard side than the SGTT, the SGTT The time from to the target ignition timing (
Regarding Fig. 8, set a time limit according to TM), wait for the elapse of the above-mentioned time limit after SGTT is actually detected, check whether an ignition signal has been generated, and check whether an ignition signal has been generated. In one example, an ignition signal is forcibly generated.

[0005]

[Operation] Therefore, according to the present invention, when the target ignition timing is set to the retarded side than the SGTT, if the ignition signal is not generated even after the time limit has elapsed after the SGTT is actually detected, the forced An ignition signal is generated automatically.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electronic control device for an internal combustion engine according to the present invention will be explained in detail below.

FIG. 2 is a block diagram showing one embodiment of this electronic control device. In the figure, 1 is a control device;
2 is a crank angle sensor, and 3 is an ignition device. The control device 1 includes an input interface 11, an output interface 12, and a microcomputer 13. The input interface 11 shapes the waveform of the signal from the crank angle sensor 2 and supplies it to the microcomputer 13 as a crank angle signal shown in FIG. The output interface 12 receives an ignition signal from the microcomputer 13 and drives the ignition device 3. The microcomputer 13 is a well-known one, and includes a timer 131 and a ROM 1.
32, RAM 133 is included.

3 to 5 are flowcharts for explaining the functions of the microcomputer 13. The microcomputer 13 executes the flow shown in FIG. 3 in synchronization with the crank angle signal SGTL. That is, first, in step 301, the period T1 of the SGTL is measured. Then, the process proceeds to step 302, where a map is searched based on the rotational speed determined from the period T1 and the amount of intake air determined from the signal from the air flow sensor (not shown), and the optimal ignition timing for the operating condition is determined at the target ignition timing. Find it as. Then, the process proceeds to step 303, where the ignition timer setting value T2 is calculated. That is, the time T2 from SGTL to the target ignition timing is calculated using the following equation (1). T2=T1×(76°-θ)/180°・
(1) However, in equation (1), θ is the angle from top dead center to the target ignition timing, with the advance side being positive (+) and the retarding side being negative (-).

Next, the process advances to step 304, and the time T2 obtained in the previous step 303 is set in the timer 131. Thereby, the timer 131 outputs the ignition signal after T2 time has elapsed from the detection point P2 of the SGTL.

The process then proceeds to step 305, in which a timer setting value (time limit) T0 is calculated using the following equation (2) in order to limit the ignition timing from being retarded. This time limit T0 is set in the timer 131 in synchronization with the crank angle signal SGTT. T0=T1×A/180°+α...(2) However, in equation (2), A is 6°-θ when 6°-θ>0, and A is 6°-θ when 6°-θ≦0. It is set to 0°. Further, in equation (2), α is an appropriately determined minute time.

Note that the period T1 used in the above equations (1) and (2) is a period that has been corrected to account for period fluctuations.

Next, the microcomputer 13 executes the flow shown in FIG. 4 in synchronization with the crank angle signal SGTT. Here, the time limit T0 obtained in the previous step 305 is set in the timer 131 (step 40
1). As a result, the timer 131 generates an interrupt signal after the time T0 has elapsed from the detection point P1 of the SGTT.

When the timer 131 generates an interrupt signal, the microcomputer 13 first determines whether ignition has ended in synchronization with the interrupt signal, according to the flowchart shown in FIG. 5 (step 501). That is,
It is checked whether or not an ignition signal has been generated, and if an ignition signal has been generated, the process is terminated. If no ignition signal is generated, it is determined that the crank angle signal has suddenly changed (sudden acceleration), and an ignition signal is forcibly generated in step 502 to prevent abnormal lag.

That is, as shown in FIGS. 1(a) and 1(b), the SGTT
It is assumed that ignition is performed at timing t6, which is on the retarded side. Here, when the SGTT detection timing t5 suddenly moves to t5' due to rapid acceleration, ignition is forcibly performed at t7 after T0 time has elapsed from t5', as shown in FIG. This will prevent abnormal retardation.

[0015]

As is clear from the above explanation, according to the present invention, when the target ignition timing is set to the retarded side than the SGTT, the time limit has elapsed since the SGTT was actually detected. If no ignition signal is generated, an ignition signal will be forcibly generated, and the target ignition timing will be set to SG.
It becomes possible to prevent abnormal angle retardation due to sudden acceleration when the angle is set to the retarded side than TT.

[Brief explanation of drawings]

FIG. 1 is a timing chart for explaining characteristic operations of the electronic control device shown in FIG. 2;

FIG. 2 is a block diagram showing an embodiment of an electronic control device for an internal combustion engine according to the present invention.

FIG. 3 is a flowchart for explaining processing performed in synchronization with SGTL in this electronic control device.

FIG. 4 is a flowchart for explaining processing performed in synchronization with SGTT in this electronic control device.

FIG. 5 is a flowchart for explaining timer interrupt processing in this electronic control device.

FIG. 6 is a diagram showing a crank angle signal.

[Figure 7] In a conventional electronic control device, the target ignition timing is S.
5 is a timing chart for explaining an operation to prevent abnormal retardation due to sudden acceleration when the angle is set to the advance side than GTT.

[Figure 8] In a conventional electronic control device, the target ignition timing is S.
FIG. 4 is a timing chart for explaining abnormal retardation caused by sudden acceleration when the angle is set to the retard side than GTT. FIG.

[Explanation of symbols]

1 Control device 2 Crank angle sensor 3. Ignition device 13. Microcomputer 131 Timer 132 ROM 133 RAM

Claims (1)

[Claims] 1. An electronic device for an internal combustion engine that detects a first crank angle position SGTT and a second crank angle position SGTL that is more advanced than the first crank angle position SGTT in the internal combustion engine, and calculates and sets a target ignition timing for each SGTL. In the control device, S
When the target ignition timing is set to the retarded side than GTT,
A time limit is set according to the time from SGTT to the target ignition timing, and after the SGTT is actually detected, it is checked whether an ignition signal has been generated after the time limit has elapsed. An electronic control device for an internal combustion engine, comprising ignition signal generating means for forcibly generating an ignition signal if the ignition signal is not present.