JPH0561466B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine ignition timing control method,
In particular, the present invention relates to an improvement in an ignition timing control method for retarding ignition timing by a predetermined amount when a rapid engine acceleration state is detected.

Conventionally, an air flow meter has been used to measure the amount of air taken into the engine, and an _O2 sensor has been used to detect the residual oxygen concentration in the exhaust gas.
Controls the fuel injection amount so that the air-fuel ratio of the mixture reaches the required value, or causes knocking to occur by retarding the basic ignition angle from a predetermined basic ignition advance angle based on the intake air amount and engine speed. Engines are known that control the ignition timing by increasing or decreasing the ignition timing depending on the engine operating state. In this engine, when the throttle valve is suddenly opened due to sudden acceleration from the throttle valve closed state, the pressure between the throttle valve and the engine combustion chamber becomes lower than the pressure between the air flow meter and the throttle valve, and is instantaneously measured by the air flow meter. In addition to this, more air is supplied to the engine than the amount of intake air required for the engine, and as the pressure at the intake port increases, the amount of fuel adhering to the walls of the combustion chamber increases. Excessive amounts of fuel components will be inhaled. As a result, the air-fuel ratio becomes leaner than the required value, and the actual engine load becomes higher than the measured load expressed by the ratio of the intake air amount to the engine speed, making knocking more likely to occur.

Therefore, conventionally, a throttle sensor is attached to the throttle valve to detect sudden acceleration of the engine when the throttle valve is suddenly opened, and the ignition timing is immediately retarded by a predetermined amount when the engine suddenly accelerates. However, with this conventional method, the ignition timing remains retarded when the engine suddenly accelerates even if no knocking has actually occurred, resulting in an unnecessary drop in output and deterioration of acceleration feeling. Ta.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an engine ignition timing control method that does not perform unnecessary retard control when the engine suddenly accelerates and does not worsen the acceleration feeling. shall be.

In order to achieve the above object, the present invention provides a correction retard amount that retards the ignition timing when the occurrence of knocking is detected within the knocking control region and advances the ignition timing when the occurrence of knocking is not detected. In addition to calculating the sudden acceleration retardation amount, which retards the ignition timing when a sudden engine acceleration state is detected, and then gradually decreases the retardation amount at predetermined period intervals, the system calculates the sudden acceleration retardation amount that retards the ignition timing when a sudden engine acceleration state is detected, and then gradually decreases the retardation amount at predetermined intervals. The ignition timing of the engine is controlled using a value obtained by calculating the sum of the corrected retardation amount and the sudden acceleration retardation amount from a predetermined basic ignition advance angle. As a result, only when occurrence of knocking is detected within the knocking control region, the ignition timing is retarded by the sum of the corrected retard amount and the rapid acceleration retard amount. Note that outside the knocking control region, it is preferable that the values of the correction retard amount and the sudden acceleration retard amount be zero.

According to the present invention, the sudden acceleration retardation amount is first set to a predetermined value during sudden acceleration, especially within the knocking control region;
Then, by gradually decreasing the sudden acceleration retardation amount at predetermined intervals, the sudden acceleration retardation amount necessary when knocking occurs can be prepared according to the time from when sudden acceleration is detected until knocking occurs. When this occurs, the engine is controlled with the optimal ignition timing, resulting in the unique effect of improving acceleration feeling without reducing output.

Next, FIG. 1 shows an example of an engine to which the present invention is applied. This engine is controlled by an electronic control circuit such as a microcomputer.
As shown in the figure, an air flow meter 2 as an intake air amount sensor is provided downstream of an air cleaner (not shown). The air flow meter 2 includes a compensation plate 2A rotatably provided within the damping chamber, and a potentiometer 2B that detects the opening degree of the compensation plate 2A. Therefore, the amount of intake air is detected from the voltage output from the potentiometer 2B. Further, an intake air temperature sensor 4 is provided near the air flow meter 2 to detect the temperature of intake air.

A throttle valve 6 is disposed downstream of the air flow meter 2, a throttle sensor 22 for detecting sudden acceleration of the engine is attached to the throttle valve 6, and a surge tank 8 is disposed downstream of the throttle valve 6. ing. An intake manifold 10 is connected to the surge tank 8, and a fuel injection valve 12 is disposed protruding into the intake manifold 10. The intake manifold 10 is connected to a combustion chamber 14A of the engine body 14, and the combustion chamber 14A of the engine is connected via an exhaust manifold 16 to a catalytic converter (not shown) filled with a three-way catalyst. The engine body 14 is provided with a knocking sensor 18 that is composed of a microphone or the like and detects engine vibrations caused by combustion. Note that 20 is a spark plug, and 24 is a coolant temperature sensor that detects the engine coolant temperature.

Spark plug 2 attached to engine body 14
0 is connected to a distributor 26, and the distributor 26 is connected to an igniter 28. The distributor 26 is provided with a cylinder discrimination sensor 30 and an engine rotation angle sensor 32, each of which includes a pickup fixed to the distributor housing and a signal rotor fixed to the distributor shaft. . This cylinder discrimination sensor 30 outputs a cylinder discrimination signal to an electronic control circuit 34 composed of a microcomputer or the like every 720 degrees of the crank angle, and the engine rotation angle sensor 32 outputs a cylinder discrimination signal based on the crank angle every 30 degrees of the crank angle. A position signal is output to the electronic control circuit 34.

As shown in FIG. 2, the throttle sensor 22 includes a substantially L-shaped rotating piece 80 whose base end is connected to the rotating shaft 6a of the throttle valve 6. One end of a first contact 82 is fixed to the base end of the rotating piece 80 so as to extend in the direction of the distal end of the rotating piece 80 and not come into contact with the distal end of the rotating piece 80 . Furthermore, one end of a second contact 86 is fixed to the tip of the rotating piece 80 via an insulating material 84 so as to be parallel to the first contact 82 . This second contact 86 is grounded. Comb-shaped first electrode 88
and a comb-shaped second electrode 90 are arranged to face the first contact 82 with the teeth of the other electrode interposed between the teeth of the electrodes. 1st
One end of the electrode 88 and the second electrode 90 is connected to a resistor 9, respectively.
2. Connected to the power supply via the resistor 94,
Each is connected to an electronic control circuit 34.

In this throttle sensor, when the throttle valve 6 is rotated in the opening direction (in the direction of the arrow in the figure), the rotating piece 80 rotates and the first contact 8
2 and the second contact 86 are in contact with each other, the tip of the first contact 82 is connected to the first electrode 88 and the second electrode 90.
Since the wire is alternately contacted and grounded, a pulse signal having a waveform as shown in FIG. 3 is output. Note that when the throttle valve is rotated in the closing direction, the first contact 82 and the second contact 86 are rotated in a non-contact state, so that no pulse signal is output.

As shown in FIG. 4, the electronic control circuit 34 includes a random access memory (RAM) 36, a read-only memory (ROM) 38, a central processing unit (CPU) 40, a clock (CLOCK) 41,
First input/output port 42, second input/output port 4
4, a first output port 46 and a second output port 48, RAM 36, ROM 3
8. The CPU 40, CLOCK 41, first input/output port 42, second input/output port 44, first output port 46, and second output port 48 are connected by a bus 50 such as a data bus or a control bus. There is.

The first input/output port 42 is connected to an air flow meter 2, a cooling water temperature sensor 24, an intake air temperature sensor 4, etc. via a buffer (not shown), a multiplexer 54, and an analog-to-digital (A/D) converter 56. has been done. This multiplexer 54
The A/D converter 56 is controlled by a control signal output from the first input/output port 42.
A first electrode 88 and a second electrode 90 of the throttle sensor 22 are connected to the second input/output port 44, and a cylinder discrimination sensor 30 and an engine rotation angle sensor 32 are also connected via a waveform shaping circuit 64. ing. Furthermore, the knocking sensor 18 is connected to the second input/output port 44 via a bandpass filter 60, a peak hold circuit 61, a channel switching circuit 66, and an A/D converter 68. This bandpass filter 60 is connected to a channel switching circuit 66 via an integrating circuit 63. A control signal for inputting either the output of the peak hold circuit 61 or the output of the integrating circuit 63 to the A/D converter 68 is input to the channel switching circuit 66 from the second input/output port 44. and the peak hold circuit 61
A reset signal and a gate signal are inputted from the second input/output port 44.

Further, the first output port 46 is connected to the igniter 28 via a drive circuit 70, and the second output port 48 is connected to the fuel injector 12 via a drive circuit 72.
It is connected to the.

The ROM 38 of the electronic control circuit 34 stores in advance a map of the basic ignition advance angle expressed by the engine speed and the amount of intake air (or load), the basic fuel injection amount, etc., and is inputted from the air flow meter 2. Signal and engine rotation angle sensor 32
The basic ignition advance angle and the basic fuel injection amount are read based on the signals input from A corrected retard amount and a corrected fuel injection amount are added to the injection amount, and the igniter 28 and fuel injection valve 12
is controlled.

Next, an embodiment in which the present invention is applied to the engine as described above will be described in detail. In addition,
In describing the embodiments of the present invention, the main routines of fuel injection control, air-fuel ratio control, ignition timing control, etc. are the same as those in the prior art, and therefore their descriptions will be omitted.

First, a routine for calculating the sudden acceleration retard amount θ _AC for retarding the ignition timing when a sudden engine acceleration state is detected will be described.

FIG. 5 shows an interrupt routine that is interrupted at the fall of the pulse signal output from the first and second electrodes of the throttle sensor. In step 100, it is determined whether the interrupt is caused by a falling edge of the pulse signal output from the first electrode. If the interrupt is due to a signal from the first electrode, the step
After clearing the sudden acceleration judgment timer T _AC in step 101, proceed to the main routine. On the other hand, if the interrupt is caused by a fall of the pulse signal output from the second electrode, it is determined in step 102 whether or not the sudden acceleration determination timer T _AC is below a predetermined value (for example, 12), that is, whether or not there is a sudden acceleration. to decide. This timer T _AC counts the time between the fall of the pulse signal output from the first electrode and the fall of the pulse signal output from the second electrode, and the count value of the timer T _AC is The smaller the value, the more rapid the acceleration. Timer T _AC
When the count value exceeds the predetermined value, the engine is not suddenly accelerating, and the process returns to the main routine.
When the count value of timer T _AC is less than the predetermined value,
Since the engine is rapidly accelerating, the value of the sudden acceleration retardation amount θ _AC is set to a predetermined value (for example, 8° C.A.) in step 103, and the process returns to the main routine.

FIG. 6 shows a routine starting from the middle of an interrupt routine that is executed every predetermined time (for example, 4 msec). In step 104, the count value of the sudden acceleration determination timer T _AC is increased by 1, and in step 105
, the count value of timer T _AC is a predetermined value (e.g.
12) Determine whether the following has occurred. Timer T _AC
When the count value of timer T AC is less than a predetermined value, the rapid acceleration retardation amount θ _AC is decreased by a predetermined amount (for example, 0.1°C A) in step 107, and when the count value of timer T _AC exceeds a predetermined value, an overflow is prevented. After setting the count value to a predetermined value (for example, 13) in step 106,
Proceed to 107. In the next step 108, it is determined whether the value of the sudden acceleration retardation amount θ _AC is greater than or equal to 0°C A. If it is greater than or equal to 0°C A, the routine proceeds to the next routine, and if the sudden acceleration retardation amount θ _AC is a negative value. If so, in step 109, the value of the rapid acceleration retardation amount θ _AC is set to 0°C A and the process proceeds to the next routine. This calculated sudden acceleration retardation amount θ _AC is stored in the RAM.

As a result of the above, as shown by the chain line in Fig. 8, when sudden engine acceleration is detected, the sudden acceleration retardation amount θ _AC is set to a predetermined value (8°C A), and when no sudden engine acceleration is detected, the sudden acceleration retardation amount θ AC is set to a predetermined value (8°C). The rapid acceleration retardation amount θ _AC is decreased by a predetermined amount (0.01°C) every 4 msec) to 0°C.

FIG. 7 shows a routine for controlling the ignition timing using the sudden acceleration retardation amount θ _AC calculated as described above. This routine is executed by an interrupt every predetermined crank angle (120°A). In step 110, the ratio of the intake air amount to the engine speed, that is, the load, is determined, and it is determined whether or not this load is greater than a predetermined value, that is, whether or not it is in the knocking control region. If it is not in the knocking control region, in steps 111 and 112, the rapid acceleration retardation amount θ _AC1 that actually controls the ignition timing and the corrected retardation amount _θK depending on the presence or absence of knocking are set to 0° C.A, and the process proceeds to step 118. In step 113, a predetermined crank angle range (for example, 10°C
ATDC~50℃A near ATDC), bandpass filter 60, peak hold circuit 61,
Channel switching circuit 66 and A/D converter 68
Predetermined frequency band (7~8KHz) input via
A constant k is applied to the peak value a of the electric signal of Compare with the judgment level kb multiplied by . When the peak value a exceeds the judgment level kb, it is determined that knocking has occurred, and in step 114, the correction retard amount θ _K is set to a predetermined amount (for example, 0.4°C A).
Increase it and proceed to step 115. Further, when the peak value a is less than the determination level kb, it is determined that knocking does not occur, and the corrected retard amount θ _K is decreased by a predetermined amount (for example, 0.08°C A) in step 116.
In step 117, it is determined whether the sudden acceleration retardation amount θ _AC1 subtracted from the basic ignition advance angle θ _BASE in the previous interrupt is 0°C. When the sudden acceleration retardation amount θ _AC1 is 0°C, the process directly proceeds to step 118. On the other hand, when the sudden acceleration retardation amount θ _AC1 is not 0℃A, the step
The process proceeds to step 118 by using the value of the sudden acceleration retardation amount θ _AC calculated in step 115 as the sudden acceleration retardation amount θ _AC1 that actually controls the ignition timing. In step 118, ignition is performed at a value obtained by subtracting the sum of the correction retard amount θ _K and the sudden acceleration retard amount θ _AC1 from the basic ignition advance angle θ _BASE stored in the ROM in advance according to the engine speed and load. Let the advance angle be θ. Then, the igniter is controlled so that it is ignited at the ignition advance angle θ in the next rechin.

As described above, when the engine suddenly accelerates, the ignition timing is retarded only when the occurrence of knocking is detected. Incidentally, the relationship between the occurrence of knocking and the sudden acceleration retardation amounts θ _AC and θ _AC1 is shown in FIG.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an engine to which the present invention is applied, FIG. 2 is a circuit diagram showing details of a throttle sensor, and FIG. 3 is a diagram showing a signal waveform output from the throttle sensor. Figure 4 is a block diagram showing details of the electronic control circuit in Figure 1, Figure 5 is a flowchart showing a routine for detecting sudden acceleration and determining the amount of sudden acceleration retardation, and Figure 6 is a flowchart showing the sudden acceleration retardation amount. FIG. 7 is a flow chart showing a routine of an embodiment of the present invention, and FIG. 8 shows the relationship between the occurrence of knocking and the sudden acceleration retardation amounts θ _AC and θ _AC1 . It is a line diagram. 6...throttle valve, 22...throttle sensor, 34...electronic control circuit.

Claims (1)

[Scope of Claims] 1. Calculates a correction retard amount that retards the ignition timing when the occurrence of knocking is detected within the knocking control region and advances the ignition timing when the occurrence of knocking is not detected, and When a sudden acceleration condition is detected, the ignition timing is retarded by a predetermined amount,
Thereafter, at every predetermined period, a sudden acceleration retardation amount is calculated to gradually reduce the retardation amount, and when the occurrence of knocking is detected, the correction retardation amount and the sudden acceleration retardation amount are calculated from a predetermined basic ignition advance angle. An engine ignition timing control method that controls the ignition timing using a value calculated by adding the angular amount. 2. The engine ignition timing control method according to claim 1, wherein the values of the correction retard amount and the sudden acceleration retard amount are set to zero outside the knocking control region.