JPS59168271A - Ignition timing control of engine - Google Patents

Abstract

PURPOSE:To permit optimum knocking control at all times by a method wherein the decision level of knocking is changed in accordance with the temperature of cooling water in the method wherein the ignition timing is controlled by comparing the output of a knock sensor with a predetermined decision level and judging the generation of knocking. CONSTITUTION:Upon operating the engine, a control circuit 34 inputs the output signal of the knock sensor 18, detecting the vibration of the engine, to compare with the predetermined decision level during a period in which the knocking can be generated and when it is decided that the knocking is generating, the circuit 34 effects the delay control of the ignition timing. In this case, the control circuit 34 inputs the output signal of a cooling water temperature sensor 24 and changes the above-described decision level in accordance with the temperature of the engine cooling water. When the temperature of engine cooling water is low, the circuit increased the decision level and, on the contrary, when the cooling water temperature is high, the circuit decreases the decision level. According to this method, the optimum knocking control may be effected in the whole area of the cooling water temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of the Invention The present invention relates to an engine ignition timing control method, and specifically, compares a knock sensor detection output with a predetermined determination level and determines whether knocking has occurred. The present invention also relates to an ignition timing control method for optimally controlling the ignition timing of an engine based on the determination result.

Conventional technology Knocking is detected by detecting engine vibration and comparing the engine vibration under conditions where no knocking occurs and the engine vibration during a period when knocking may occur.When the engine is busy and the engine speed is low. Under conditions where the engine vibration itself is small, the vibration level changes sharply relative to the absolute level of engine vibration (and the criterion for determining whether or not knocking occurs becomes unstable).

Therefore, under conditions of low engine vibration, such as when the engine speed is low, the presence or absence of knocking is determined based on the absolute value of the vibration level detected by the knock sensor during the period in which knocking can occur. knocking can be detected more accurately.

However, when the engine cooling water temperature is low, the fluctuations in engine rotation, etc. are large (and the changes in engine vibration are even larger than after the engine has been warmed up, so the knock is optimal when the engine is warmed up). If the determination level is set, there is a problem in that even though the button does not cause knocking, it is erroneously determined that knocking has occurred, and the ignition timing is retarded.

Conversely, the knock detection level is increased to suit the condition where the engine cooling water temperature is low (this results in the knock detection level being too high for the engine vibration level after the engine warms up, even though knocking occurs). However, it was determined that knocking had not occurred, and the ignition timing control was not performed properly.

OBJECTS OF THE INVENTION An object of the present invention is to provide an engine ignition timing control method that allows appropriate knock control over the entire range of engine cooling water temperatures.

Concept of the Invention The present invention compares the detection output of a knock sensor with a predetermined determination level, determines the presence or absence of knocking, and controls the ignition timing of an engine based on the determination result. This system is characterized in that the level is changed according to the engine cooling water temperature.

Embodiments of the Invention The overall configuration of an engine control device to which the present invention is applied is described in a first embodiment.
As shown in the figure. As shown in the figure, the engine main body 14 includes an air flow meter 2 as an intake air amount sensor provided downstream of an air cleaner (not shown).

The air flow meter 2 is composed of two convenion motion plates rotatably installed in the damping chamber and a potentiometer 2B that detects the opening 11 of the convention plate 2A (7). Therefore, the intake air amount Q is detected as 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 arranged downstream of the air flow meter 2, and a surge tank 8 is arranged downstream of the throttle valve 6.
is provided. An intake manifold 10 is connected to the surge tank 81C, 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 knock sensor 18 configured with a microphone or the like to detect vibrations of the engine.

In addition, 20 is a spark plug, and 22 is a 0.0. A sensor 24 is a coolant temperature sensor that detects the engine coolant temperature.

The engine main body 140 spark plug 20 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 and a signal rotor fixed to the distributor shaft. This cylinder discrimination sensor 3
0 outputs a cylinder discrimination signal to a control circuit 34 made up of a microcomputer or the like every 720 degrees of crank angle, and this engine rotation angle sensor 32 controls a crank angle reference position signal every 30 degrees of crank angle. Output to circuit 34.

The control circuit 34 includes one random e-access memory (RAM) 36 and a read-only memo!, as shown in FIG. J (ROM) 38, central processing unit (CPU) 40, clock 41, first input/output port 42, second input/output port 44, first output port 46, 2 output ports 48, R
AM36, ROM38, CPU40, CLOCK41,
The first input/output port 42, the second input/output port 44, the first output port 46, and the second output port 48 are connected by a path 50.

An air flow meter 2, a cooling water temperature sensor 24, an intake air temperature sensor 4, etc. are connected to the first input/output boat 42 via a buffer (not shown) multiplexer 54 and an analog-to-digital (A/D) converter 56. has been done. The multiplexer 54 and A/D converter 56 are controlled by a signal output from the first input/output port 42.

The second input/output port 44 is connected to 0.0 through a buffer (not shown) and a comparator 62. The sensor 22 is connected to the cylinder f-11 separate sensor 3 via the waveform shaping circuit 64.
0 and an engine rotation angle sensor 32 are connected.

Further, 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 is connected to a channel switching circuit 66 via an integrating circuit 63. This channel switching circuit 66 includes an input/output port 4 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.
4, and a reset signal from the second input/output port 44 is input to the peak hold circuit 61.

Further, the first output boat 46 is connected to the igniter 28 via a drive circuit 70, and the second output boat 4B is connected to the fuel injection valve 12 via a drive circuit 72.

The ROM 38 of the control circuit 34 stores in advance a map of the basic ignition advance angle θBASE expressed by the engine speed and intake air amount, the basic fuel injection amount, etc. 3
The basic ignition advance angle and basic fuel injection amount are successively outputted by the signals from 2, and the basic ignition advance angle and the basic fuel injection amount are continuously outputted by various signals including the signals from the cooling water temperature sensor 24 and the intake temperature sensor 4. A corrected ignition advance angle and a corrected fuel injection amount are added, and the igniter 28 and fuel injection valve 12 are controlled.

0! The air-fuel ratio signal output from the sensor 22 is used for air-fuel ratio control to control the air-fuel ratio of the air-fuel mixture to near the stoichiometric air-fuel ratio.

Next, an embodiment in which the present invention is applied to the engine as described above will be described in detail. □In addition, in explaining the present invention in detail, the main routines of fuel injection control, air-fuel ratio control, ignition timing control, etc. are the same as conventional ones, so their explanation will be omitted, and only the knocking control routine related to the present invention will be explained. Let me explain about K.

FIG. 3 shows the contents of an interrupt routine activated every 30° CA when the present invention is implemented using a microcomputer. First, in step 81, the engine rotation speed N is calculated from the rotation time based on the signal from the engine rotation angle sensor 32, and in step 82, the number of interruptions after the cylinder discrimination signal is input from the cylinder discrimination sensor 30 is counted. Sets a flag indicating the current crank angle.

Next, in step 83, it is determined whether the flag set in step 82 is a top dead center (TDC) flag.

If the current position is not the top dead center, the process proceeds to step 8B, and if the current position is the top dead center, it is determined in step 84 whether or not the knock gate is closed.

When the knock gate is open, the knock gate is closed in step 85, and when the knock gate is closed, the channel switching circuit 66 is switched in step 86, and the engine vibration signal output from the knock sensor 18 is passed through the band pass filter 60. ．． The signal is input to the A/D converter 68 via the integrating circuit 63 and the channel switching circuit 66, and starts A/D conversion of the average value of engine vibration, that is, the background level.

Subsequently, in step 87, the knock gate is turned to the closing side t.
I, that is, the next time to close the knock gate, is calculated and a time coincidence interrupt A is set.

Next, in step 88, based on the flag set in step 82, it is determined whether the crank angle has reached 906 CA, BTDC (before top dead center).

If the crank angle is not 90" CA% BTDC, the process proceeds to step 91; if it is 90° CA, BTDC', the correction advance amount θ is updated to step 89, and the co-pressure ignition timing calculation process is performed. (described below).

In step 90, the time to turn on the igniter 28 is determined based on the ignition timing calculated in step 89 and the current time, and time-monbetsu-include B is set, and an igniter-on flag is set.

Then, in step 91, the crank angle is 601'C.
A. Determine whether it has become BTDC, 60° CA, B
If it is not TDC, return to the main routine and step 6
If it is 0° CA and HTDC, the igniter off time is calculated in step 92, time-monbetsu-include B is set, and the igniter on flag set in step 90 is lowered.

Next, the time-monbetsu included AK shown in FIG. 4 will be explained.

This interrupt routine is to find the peak value of engine vibration, and when the time set in step 87 in FIG. A/D conversion is started via 66 and the process returns to the main routine.

(11) FIG. 5 shows the time-monbetsu-include B routine, and an interrupt is made when the time set in step 90 and step 92 of FIG. 3 comes.

In step 94, it is determined whether the igniter on flag is set, that is, whether this flag is 1. If the flag is set, the igniter is turned on in step 96, and if the flag is off, the igniter is turned on in step 95. Turn off and return to the main routine.

FIG. 6 shows an A/D conversion completion interrupt routine, and this interrupt is performed when the background level A/D conversion and the peak hold value A/D conversion are completed. First, in step 97, it is determined whether the knock gate is currently open. When the knock gate is closed, in step 98, K stores the A/D conversion value converted in step 86 in FIG.
Open the knock gate and return to the main routine. On the other hand, when the check gate is open (12), the A/D conversion value converted in step 93 of FIG. 4 is stored in the memory of the RAM 36 and set as the peak value a.
In step IOI, the knock gate is closed and the process returns to the main routine.

FIG. 10 shows an interrupt routine that is performed every predetermined time (for example, 4m8eC) to count the time when no knocking occurs. First, in step 102, the count value of timer TIME10, which calculates the time when knocking does not occur, is increased by 1,
In the next step 103, the timer 'I' I M E
It is determined whether the count value of 1 is less than 12 (48 m5ec) or not.

When the count value exceeds 12, K goes to step 105.
, set the count value of timer TIM E 1 to 12.
When the count value is 12 or less, K returns to the main routine.

Next, the detailed routine of step 89 in FIG. 3 will be explained based on FIG. 8.

Fig. 8 shows the contents of the ignition timing control interrupt routine that is activated every 90 degrees of crank angle. It is determined whether or not.Step 20
If it is determined that /l Y e811 at 0, the peak value a of the detection output of the knock sensor 18 is determined in the next step 202.
It is determined whether or not is 5 Qmv or more, and if the determination in step 202 is "Yes", the button is further set in step 204 to the peak value a stored in step 100 in FIG. 6 and step 98 in the same figure. b is compared with the value obtained by multiplying the background level b stored in , by a constant K. Then, in step 204, it is determined that knocking has occurred in the engine when the peak value a exceeds the multiplied value -b, and in step 206, the correction retard amount θK is set to a predetermined angle (for example, 0
．． 4'CA) is set as the corrected retard amount θ, and the process moves to step 208.

On the other hand, if the determination in step 200 is "No", the process moves to step 212, where it is determined whether the peak value a is equal to or less than 7 Qmv.

If the determination in step 212 is "NO", the process moves to step 202 and a similar determination is made. On the other hand, if the determination in step 212 is #Yes II or if the determination in steps 202 and 204 is "II NO", the process moves to step 214, and in step 214, a timer 'r is set to measure the time during which no knocking occurs.
It is determined whether the content of I M El has reached 12, in other words, whether a predetermined period of time has elapsed without knocking. “Yes” in step 214
If it is determined that the corrected retard amount θK is subtracted by a predetermined angle (for example, 0.08 and CA), the corrected retard amount θ is set as the t-corrected retard amount θ, and the process proceeds to step 208. In step 208, the timer TIMEIY is reset, and the process moves to step 210. If it is determined in step 214 that LL No #, the process similarly moves to step 210, and in step 210, the ignition timing is determined by subtracting the correction retard amount from the basic ignition advance angle θBASE, and the process moves to another routine.

As explained above, in this embodiment, the knock determination level is lowered when the background level of the knock sensor 18 is small, and in order to prevent false detection of knocking, the engine cooling water temperature is set to 70 mV when the engine coolant temperature is low.

After warming up the engine, all knock sensor outputs below K 5 Q m v are determined to indicate that knocking has not occurred.

Next, FIG. 9 shows another embodiment of the ignition timing control interrupt routine. In the same figure, when the interrupt routine is started,
In step 300, it is determined whether the background level b of the background knock sensor 18 exceeds lQmv'4.

If it is determined "Yes" in step 300, it is determined in the next step 302 whether or not the knock sensor peak value a exceeds the value obtained by multiplying the background level bK multiplier K by @b. In step 304 where the determination is "Yes", the corrected retard amount θK is added by a predetermined angle (for example, 0.4 CA), and the result is determined as the corrected retard amount, and the process moves to step 306. On the other hand, #No# in step 300
If it is determined that
6) It is determined whether or not the following is true, and in step 310 #Ye8
If it is determined as "NO" in step 310, the background level of the knock sensor 18 is biroomv, and the process moves to step 320.If it is determined as "NO" in step 310, it is further determined in step 314 whether or not the water temperature is below 00C. is determined, and if it is determined as "Yes" in step 314, b-(water temperature/-30'X5) is determined in step 316.
0+50) mv, and the process moves to step 320. On the other hand, if the determination in step 314 is #No'', the background level b of the knock sensor 18 is set to 59mv in step 318, and the process moves to step 320. In step 320, the peak value a of the knock sensor 18 and the background level b are If the peak value a is greater than the background level b, step 3 is performed.
Move to 04. On the other hand, if the peak value a is smaller than b, and if the determination in step 302 is "No", then in step 320 it is determined whether or not the content of the timer TIMEI, which measures the time during which no knocking occurs, has reached 12, i.e. A determination is made as to whether a predetermined period of time has elapsed without knocking. In step 322 #
If it is determined that "Y e s", the corrected retard amount is determined by subtracting a predetermined angle (for example, 0.08 CA) from the corrected retard amount θK in step 324, and the process moves to step 306.In step 306, the timer T I M E 1'
& reset, and proceed to step 308. Step 3
Similarly, if the determination in step 20 is “No”, proceed to step 3.
Move to 08. In step 308, the basic ignition advance angle θB
The ignition timing is determined by subtracting the corrected retardation amount θK from ASE, and the process proceeds to another routine.

In this embodiment, the background level b of the knock sensor 18 is changed according to the engine cooling water temperature as shown in FIG. Even if the knock sensor 18 detects 50 mv or more, it is treated as if no knocking occurs if it is determined that knocking does not occur with normal knock footing. - It is configured to determine that knocking has occurred under certain conditions.This embodiment is suitable for engines where the engine vibration level fluctuates significantly depending on the engine cooling water temperature. The knocking detection accuracy is superior to that of the embodiment shown in FIG.

Effects of the Invention According to the present invention, it is possible to appropriately control knocking over the entire engine cooling water temperature range, thereby improving the durability of the engine.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of an engine control device to which the present invention is applied, Fig. 2 is a block diagram showing a specific configuration of the control circuit in Fig. 1, and Fig. 3 is an interrupt activated every 30° CA. Flowchart showing the contents of the routine, FIG. 4 is a 74-chart of time coincidence interrupt A, FIG. 5 is a flowchart showing the contents of time coincidence interrupt B, and FIG.
Flowchart showing the contents of the D completion interrupt routine, No. 7
The figure shows the interrupt routine (
19) FIG. 8 is a flowchart showing the contents of the ignition timing control interrupt routine, FIG. 9 is a flowchart showing the contents of another embodiment of the ignition timing control interrupt routine, and FIG. 10 is a flowchart showing the contents of the ignition timing control interrupt routine. It is a figure which shows the relationship between the background level b of a knock sensor with respect to water temperature. 2... Air flow meter, 12... Fuel I'll'
, 18... Knock sensor, 28... Igniter, 3
4...Control circuit, 36...RAM, 38...RO
M. 56・68...A/D converter. Agent Tatsuyuki Unuma (and 2 others) (20) Figure 4 Figure 5゜Figure 6 Figure 8 Figure 9

Claims (2)

[Claims] (1) The detection output of the knock sensor is compared with a predetermined determination level, the presence or absence of knocking is determined, and the ignition timing of the engine is controlled based on the determination result. An engine ignition timing control method characterized by changing the ignition timing according to the engine cooling water temperature. (2) The engine ignition according to claim (1), wherein the determination level is set high when the engine cooling water temperature is low (and conversely set low when the engine cooling water temperature is high). Timing control method.