JPS58195066A - Ignition timing controller for internal-combustion engine - Google Patents

Abstract

PURPOSE:To eliminate the necessity for using an acceleration detector, by discriminating an accelerating condition through the interval of knocking generation in an ignition timing controller of an engine using a knocking feedback. CONSTITUTION:A knocking signal is input from an input port 8009 for a digital signal. An ROM8001 and RAM8002 are used by a CPU8000 to control ignition timing. An acceleration condition is decided, and a timing control speed of the ignition timing is charged in accordance with this result. The instant of an acceleration is judged by the status of generating knocking (for instance, the interval of generation) further whether the status reaches a steady condition or not is decided in accordance with the internal of generating knocking or the like thereafter. The timing control speed is increased only during this time. In this way, the necessity for an acceleration detector is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an ignition timing control device (hereinafter referred to as a knock control system) that has a function of detecting engine knock and advancing or retarding the ignition timing.

In recent years, various knock control systems have been studied that detect knock occurring in an engine and advance or retard the ignition timing depending on the state of the knock.

By using this knock control system, the ignition timing can always be controlled close to the knock limit, and engine variations, including engine variations, are not affected by changes over time, etc., and the engine's fuel efficiency and output performance are maximized. You can draw it out in the dark.

However, the conventional knock control system has a serious problem in that acceleration failure occurs when the engine accelerates. In other words, this is a sluggish acceleration that occurs after the ignition timing is significantly retarded due to knocks that occur continuously immediately after acceleration.

This occurs because the required ignition timing changes rapidly during transient conditions, particularly during rapid acceleration, and the advance operation speed of the knock control system cannot follow the change. It is generally known that the greater the amount of angle advanced per unit time or unit cycle (hereinafter referred to as advance angle speed) calculated in a fixed manner, the better the followability during transient times will be.

However, when the advance angle speed is increased, ignition timing fluctuations in steady state become larger, resulting in excessive torque fluctuations, and as a result, drivability in steady state deteriorates. Therefore, conventional knock control systems adopt a compromise between steady and transient performance (for example, advance angle speed of about 1°CA/1 second), so both constant and transient performance (particularly transient performance) is achieved.
I couldn't make it add up. Therefore, in order to fundamentally solve the sluggishness of acceleration, it is necessary to increase the advance angle speed only during acceleration and maintain a small advance angle speed during steady state.

One possible method for this is to determine the acceleration state by detecting the engine state (for example, rotational speed, manifold pressure, etc.) and change the advance angle speed in accordance with this result. However, the engine knock condition,
Therefore, the retard state of ignition timing is greatly affected by environmental conditions or changes over time, so if acceleration is judged based on information from engine conditions and the advance speed is carelessly increased, the ignition timing will almost always be at the required ignition timing in a steady state. Despite this, in order to advance the angle quickly, excessive knocking occurs repeatedly and torque fluctuations become excessive. This is due to the fact that the advance/retard angle speed is manipulated regardless of the knock state or retard state during acceleration and the subsequent knock state or advance state.

In view of the above-mentioned problems, the present invention determines when to accelerate based on the state of occurrence of knocks, and appropriately determines whether a steady state has been reached according to the interval between subsequent knock occurrences or knock intensity, and speeds up the acceleration/deceleration only during that time. The object of the present invention is to provide an ignition timing control device that solves sluggish acceleration and improves steady-state drivability by increasing the speed.

The technical rationale of the present invention will be explained below. First, three methods for determining acceleration based on the occurrence of knock will be explained.

The first method will be described below. The biggest difference between the knock occurrence patterns between the steady state and the accelerated state is the knock occurrence frequency. In other words, during steady state, knock occurs sporadically, so the knock frequency is low; on the other hand, when accelerating, knock occurs frequently, so the knock frequency is high. Regarding the knock interval (referred to as interval), the interval between knock occurrences is long during steady state, and short during acceleration.

However, when this was studied in detail, it was found that even in a steady state, there are cases where the knock occurrence interval is short, and in this case, increasing the advance/retardation angle deteriorates the drivability in the steady state.

In connection with this, the inventors have discovered that it is possible to accurately distinguish between acceleration and steady state by using whether or not a relatively strong knock has occurred in a short period of time. In other words, although the knock interval may be short during steady state,
There are no cases where relatively strong knocks occur consecutively in a short period of time, and such knocks occur only during acceleration.

Next, a second method for determining acceleration will be described.

If you look closely at the ignition timing control conditions during steady state and acceleration, there are important differences. This will be explained using FIG. 15. In FIG. 15, (a) shows the ignition timing control state during steady state, and (b) shows the ignition timing control state during acceleration. (c) In the figure, the sum of the retard amounts that are continuously retarded without ever advancing (S1, S2, S3
etc.) is found to be relatively small. Compared to this, 54Fi in the I cut is extremely large. Then, when the retarded state passes and a steady state is reached, it becomes smaller again (like S■).

In other words, if the sum S of the retard amounts that are continuously retarded without ever being advanced is used as the determining means, it is possible to accurately determine whether the engine is accelerating or not.

Next, a third method for determining acceleration will be described.

As mentioned above, when looking at the knock-to-hook interval or the ignition cycle interval (hereinafter referred to as knock occurrence interval), the knock occurrence interval is long during steady state, and becomes short during acceleration. If this characteristic is utilized as a means for determining whether the knock occurrence interval is short several times or not, it is possible to accurately determine whether the vehicle is accelerating or not. That is, while the knocking interval may be short during steady state, there are no cases where knocking occurs several times in a row, and such knocking only occurs during acceleration.

Of course, judging from the engine conditions, even if the engine is accelerating, if there are not many knocks due to environmental conditions, etc., these methods will determine that the engine is not accelerating, but in this case, the advance angle speed should be increased. These methods make sense because you don't have to do it. 'Next, a method for decreasing the advance angle speed when the steady state is reached after increasing the advance angle speed will be described. First, if the advance angle speed increases after acceleration, the target value of the advance angle is
The basic ignition timing determined by the pace map of the distributor or microcomputer (i.e., the ignition timing with 0 retardation amount by the knock control system), or the ignition timing that is slightly delayed from the basic ignition timing (i.e., the retardation amount is a predetermined amount α) ignition timing) is good.

However, in many cases, before the ignition timing is advanced to the target ignition timing, the knock limit ignition timing in the steady state is passed, so knocking occurs. Therefore, when a knock occurs and the knock interval becomes shorter than a predetermined time (average knock occurrence interval in steady state), or when a knock of a magnitude greater than a predetermined value occurs based on the knock intensity determination, the advance angle speed is decreased. If so, it is possible to smoothly shift to a stable control state at steady state.Furthermore, the time when the advance angle speed starts to increase as mentioned earlier.

The effect will be further improved if the knock generation pattern satisfies the above-mentioned conditions by a short amount of time (by a predetermined period of time or by a predetermined cycle).This will ensure that the knock during acceleration passes during the delay, and therefore reduce the overload speed. This is because the knock that occurs after increasing is definitely a steady state knock.

The present invention will be explained below with reference to embodiments shown in the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention. In Fig. 1, 1 is a 4-cylinder 4-cycle engine, 2 is an air cleaner, 3 is an air flow meter that detects the intake air amount of the engine and outputs a signal in accordance with this, 4 is a throttle valve, and 5 is a reference crank of the engine. This distributor incorporates a reference angle sensor 5A for detecting an angular position (for example, top dead center) and a crank angle sensor 5B that generates an output signal at every fixed crank angle of the engine.

6 is a knock sensor for detecting the vibration of the engine block corresponding to the engine knock phenomenon using a piezoelectric element type (piezo element type), electromagnetic type (magnet, coil), etc.; 7 is a knock sensor for detecting engine block vibration corresponding to the engine knock phenomenon; This is a knock detection circuit for detecting the occurrence of knock. 9 is a water temperature sensor that generates a signal according to the engine cooling water temperature; 12
13 is a fully closed switch (idle switch) for outputting a signal when the throttle valve 4 is fully open, and 13 is a fully open switch (power switch) for outputting a signal when the throttle valve 4 is almost fully open. , 14 is an O2 sensor that generates an output signal depending on whether the air-fuel ratio (AF) of the exhaust gas is richer or leaner than the stoichiometric air-fuel ratio.

Reference numeral 8 denotes a control circuit for controlling the ignition timing and air-fuel ratio of the engine according to input signal states from each sensor and each switch, and 10 receives an ignition timing control signal output from the control circuit 8 and sends it to an ignition coil. The high voltage optically transmitted by the ignition coil that cuts off the current flow passes through the power distribution section of the distributor 5 and ignites the spark plug of a predetermined cylinder at an appropriate time. Reference numeral 11 denotes an injector for injecting fuel into the intake manifold based on the fuel injection timing and fuel injection opening (t) determined by the control circuit 8.

Next, the detailed configuration of the knock detection circuit 7 will be explained using FIG. 2. 701 is a filter such as a bandpass or high-pass filter for selecting and extracting only the knock wave number component from the output of the knock sensor 6; 702 is a half-branch rectifier 703 for half-wave rectifying the output of the filter 701; 703 is the output of the half-wave rectifier 702; 704 is an amplifier for amplifying the output of the integrator 703 to create an appropriate knock judgment level. 705 is an amplifier for adding noise to the output of the amplifier 704. An offset voltage setter 706 consisting of a resistor and the like that shifts the voltage in order to obtain effects such as a margin adds the output of the amplifier 704 and the output of the offset voltage setter 705 to create the final knock judgment level. Adder 707 for half-wave rectification
02 and the output of the adder 706, the half-wave rectifier 702
This is a comparator that determines that knocking is occurring when the output of 708 is a counter that counts the number of pulses of this pulse signal and converts it into a parallel signal of 2 times, and is reset in synchronization with the ignition signal from the igniter 10, for example. 709
is a code converter (encoder) for dividing the parallel output of the counter 708 into cases according to the count value and converting it into a smaller number of connection lines.

The operation of this knock detection circuit will be explained using FIG. 3.

In FIG. 3, (a) shows the output signals of 74 to 701, and the knock frequency components (6 to 701) of the output of the knock sensor 6 are shown.
This is a signal extracted by selecting only 9KHz). (a)
In the figure, a2, a2, and a3 represent outputs corresponding to three different knock states. That is, a1 is a relatively small knock, a2 is a relatively large knock, and a3 is noise or an extremely small knock. (b) The figure is (a
) The signal after half-wave rectification by the rectifier 702, (
c) The figure shows the signal after integrating and amplifying the figure in (b) by an integrator 703 and an amplifier 704. (d) The figure is (c)
The figure shows the signal after the offset voltage 705 is added by the adder 706 (that is, the notch judgment level), and the output signal of the rectifier 702 (figure (b)) is also drawn for comparison. (■) The figure shows the output signal of the comparator 707.
It is a pulse signal that goes high when the output signal of the rectifier 702 (Figure (b)) is higher than the knock determination level (Figure (d)), and goes low when it is smaller. Since the number of pulses to be transmitted corresponds to the intensity of the knock (see the number of pulses for a1 and a2), the knock intensity is converted into the number of pulses by counting the number of pulses with the counter 708.

Since this counter 708 is reset in synchronization with the ignition signal, the intensity of one knock occurring for each ignition can be known for each ignition. A parallel signal corresponding to the count value of this counter 708 is input to an encoder 709. The encoder classifies the count value of the counter 708 into several groups and sends an output according to the classification to the control circuit 8. For example, if a 5-bit counter is used and two encoder output lines are used, the count values 0 to 31 are classified into four groups. In other words, there are four types of knock intensities (
No knock, small knock, knocking.

The information regarding the knock (large knock) is input to the control circuit 8. Due to the function of this encoder 709, the number of signal lines to the control circuit 8 can be significantly reduced, and the number of input ports to the control circuit 80 can be significantly reduced.

Next, the detailed configuration and operation of the control circuit 8 will be explained with reference to FIG. In Figure 4, 8000 is the central processing unit (CPU) that calculates the ignition timing and fuel injection timing.
A microgross processor with a bit configuration is used. 800
1 is a read-only memory unit (ROM) for storing control programs and control constants necessary for calculation; 8;
002 is a temporary storage unit (RA) for temporarily storing calculation data while the CPU 8000 is operating according to the program.
8003 is a waveform shaping circuit for shaping the magnetic pickup signal which is the output signal of the reference angle sensor 5A, and 8004 is also the crank angle sensor 5B.
This is a waveform shaping circuit for shaping the waveform of the output signal.

8005 is an interrupt control unit 8006 for causing the CPU to perform interrupt processing based on an external signal or an internal signal.
This timer 8006, which is a 16-bit timer configured to increase the count value by one at each clock cycle, which is the basic cycle of U operation, and the interrupt control unit 8005 determine the engine speed and crank angle position as follows. In this way, it is taken into the CPU. That is, the reference angle sensor 5A
Each time an interrupt occurs due to the output signal of By calculating the difference between the count value and the count value at the time of interruption, the time interval of the reference angle sensor signal, that is, the time required for one rotation of the engine can be measured. In this way, the engine speed is determined.

Furthermore, since the crank angle position is determined by the crank angle sensor 5B's signal being output at every fixed crank angle (for example, 30° CA), the crank angle at that time is 30° CA based on the top dead center signal of the reference angle sensor 5A. You can know it in units. This crank angle signal every 30° CA is used as a reference point for generating the ignition timing control signal.

8007 is a multiplexer for timely switching multiple analog signals and guiding them to an analog-to-digital converter (A/D converter) 8008, and the switching timing is determined by the output port 801.
It is controlled by a control signal output from 1. In this embodiment, an intake air amount signal from the air flow meter 3 and a water temperature signal from the water temperature sensor 9 are input as analog signals.

8008 is an A/D converter for converting an analog signal into a digital signal. 8009 is an input port for a digital signal, and in this embodiment, a knock signal from the knock detection circuit and an idle switch 12 are input to this port.
An idle signal from the engine, a power signal from the power switch 13, and a rich lean signal from the O2 sensor 14 are input.

801O is an output port for outputting a digital signal. An ignition timing control signal for the igniter 10, a fuel injection control signal for the injector 11, and a control signal for the multiplexer 8007 are output from this output port. 8011 is a CPU path, and the CPU puts control signals and data signals on this path signal line to control peripheral circuits and send and receive data.

Next, a method of calculating the ignition timing will be explained. 5 to 7 are flowcharts showing an example of an ignition timing calculation method.

In FIG. 5, first, the rotation speed N and load (Q/N) are determined from the signals from the reference angle sensor and air flow meter. Here, Q is the amount of intake air output from the air flow meter, and the load applied to the engine is proportional to the value obtained by dividing Q by the engine speed N (Q/N). Further, in this embodiment, the rotation speed N is measured using a reference angle sensor, but if the processing capacity of the microcomputer is sufficiently high, a crank angle sensor may be used.

Next, the basic ignition timing θ■ previously stored in the memory is calculated based on the obtained rotational speed N and load (Q/N).

This basic ignition timing θ■ is stored in the memory as a two-dimensional map of N and Q/N. Next, if the load Q/N is smaller than a predetermined value, it is determined that the load is light so that knocking does not occur, and the process branches to (2) in FIG. If the load is not light, then it is determined whether the current combustion cycle is a knock cycle based on the output from the knock detection circuit.

If no knock occurs, the process branches to (1) in FIG. If a knock occurs, it is determined whether the knock is a relatively large knock. In this embodiment, knocks are classified into three levels: large, medium, and small, and in this case, large knocks are used as large knocks.

Of course, a medium knock may be used as a relatively large knock.

Further, the knock intensity may be classified in any number of levels as long as it is two or more levels, and any knock other than the knock that is classified as the lowest level of relatively large knock may be used.

Now, if the current knock is determined to be a large knock, the large knock flag is turned on. This large knock flag is used to return the advance angle speed to its original small value if a large knock occurs when the advance angle speed is increased. In this embodiment, the flag is turned on when a large knock occurs, but any knock may be used as long as it is limited to a large knock and is not classified as the minimum knock. Next, set the retardation amount for this knock to a relatively large value (△θ=△θ3 and Δθ3 is 1.5°C
A), that is, the retardation amount Δθ depends on the intensity of the knock.
Set. (For example, if there is a small knock, △θ=0.5°C
A. For medium knock, Δθ=1°CA, for large knock, Δθ=
1.5°CA) Retard amount Δθ1 for each knock intensity (for example, Δθ1=0.5°CA).

Δθ2=1°CA, Δθ3=1.5°CA) are stored as constants in the ROM. Next, it is determined whether the knock occurrence interval is longer or shorter than a predetermined value (for example, 4 cycles). This knock occurrence interval can be known by reading the value of the cycle counter C allocated in the RAM. In other words, the counter on this software is cleared when a relatively large knock occurs, and functions to count the ignition cycles until the next relatively large knock occurs. This counter is programmed to hold that value when it counts up to a predetermined value C0. This is to prevent the counter from overshooting and jilowing.

Now, when the knock occurrence interval is long, the process proceeds to the step of calculating the corrected ignition timing, and when it is short, the value of the cycle counter C is reset to 0 and the retard amount Δθ is corrected. The reason why the retard amount Δθ is corrected when the knock occurrence interval is short is to greatly retard the angle during acceleration to enhance the effect of suppressing knock noise during acceleration. For example, by doubling the retardation amount Δθ (γ=2), the noise reduction effect during acceleration can be greatly improved.

Also, if the current knock is not a big knock.

Turn off the large knock flag and set the retard amount for medium knock and small knock (for example, Δθ1=0.5CA, Δ
θ2=1°CA). Of course, there are two types: a big knock and a small knock.
If there is only classification, it is sufficient to simply set the retard amount for small knocks. Next, the cycle counter C is counted up by one within a range not exceeding a predetermined value C0.

Next, the total amount of retardation from the basic ignition timing, that is, the corrected ignition timing θC is determined (θC=θC−Δθ).

An upper limit value θcmax is set for this corrected ignition timing θC, and the corrected ignition timing θC functions as a limiter to prevent further retardation. Then, the final ignition timing θ for the next ignition is set as θ=θ
(2) Calculate by -θC and set the value in the ignition timer. Next, the acceleration advance angle counter AC, delay counter DC, and steady advance angle counter A, which are counters on the software, are all cleared to 0.

Next, it is checked by the acceleration retardation flag whether or not the advance angle series is currently increasing. This acceleration retardation flag remains ON (ON) only while the advance angle speed is increasing. If this flag is ON and the advance angle speed change is increasing, check whether a large knock has occurred or not.
Judge with N or OFF. When ON, the advance angle speed is returned to the small value at steady state. For this reason, turn off the acceleration advance angle hook and delay flag. If a large knock did not occur (
(Large knock flag is OFF) is the knock occurrence interval (KT)
It is determined whether the timer that measures the time is shorter than a predetermined time (KT.). This time (KT■) is set to the average knock occurrence interval in steady state (for example, 0.8 seconds). If a knock occurs in a time shorter than this time (KT■), it is determined that the knock eye field in the steady state has been reached, and the advance angle speed is returned to the small value in the steady state. Further, this timer is cleared only when a knock occurs when the advance angle speed increases; otherwise, the timer is held after counting for a certain period of time (a value larger than KT■). Therefore, since the knock occurrence interval after the first knock occurrence when the advance angle speed increases is measured, the first knock (when it is smaller than the large knock)
In this case, the advance angle velocity does not return to the small value at steady state. The current knock is the second or subsequent knock when the advance angle speed increases, and the time (KT) from the previous knock occurrence is the predetermined time (K
T■), the advance angle speed is returned to the small value at steady state. For this purpose, turn off the acceleration advance angle flag and delay flag.
Make it. In addition, the knock occurrence interval (KT) is a predetermined time (KT
■) Clear the knock interval timer (K
T=0).

After that, or when the acceleration advance flag in the above judgment is OFF, the cycle counter C is set as the next step.
Find out the value of . If the value of the cycle counter C is 0, the interval between occurrences of relatively large knocks is short, so it is determined that acceleration is occurring, and preparations are made to increase the advance angle speed. That is, the delay flag is turned on and then the process returns to the main program.

Now, the calculation method when the current psyche N is not a knock cycle will be explained using FIG. In FIG. 6, it is first checked whether the acceleration lead angle flag is ON or OFF. When ON, the acceleration advance angle counter AC is counted up by one in order to perform advance angle operation at a large turning angular velocity for acceleration. This counter AC is a software counter that repeatedly counts from 0 to a predetermined value AC0. AC is a predetermined value Ac
If the current corrected ignition timing θ has not reached 0 (for example, 2 cycles), the current corrected ignition timing θ is maintained as it is. If AC0 has been reached, the counter AC is reset and a predetermined angle θ■■ (for example, 0.5° CA) is subtracted from the corrected ignition timing θC. Therefore, the ignition timing is corrected by θ■■ in the advance direction. In this case, when knock is likely to occur and acceleration advance is executed, in this example, every two cycles (AC0
If the primary corrected ignition timing θC becomes negative, this value is corrected to 0. At the same time, the acceleration advance angle flag and delay flag are turned OFF. This prevents the ignition timing from advancing beyond the basic ignition timing θ■, and also reduces the evolution speed to a small value when the basic ignition timing θ is reached (i.e., when the amount of retardation due to knock control θc = 0). This is to restore the value.

Now, in the step of determining the acceleration advance angle flag in FIG. 6, if the acceleration valve flag is OFF, the delay flag is ON or OFF.
Check FF. When the delay flag is ON, it is a preparation period for increasing the advance angle speed. In other words, the current corrected ignition timing value is maintained until the delay counter DC reaches a predetermined value DC■ (for example, 4 cycles), and when the delay counter DC reaches the predetermined value DC■, the acceleration advance angle plug is turned ON to perform the rapid advance described above. Get on the journey. Therefore, in the case of this embodiment, rapid advance starts after a delay of four cycles. If a knock occurs during this delay period, after the knock ends, there is another delay period, and then rapid advance is performed.

Further, when the delay flag is OFF, a small value for the steady state is used as the advance angle speed. This steady advance angle counter is a steady advance angle counter A. This counter A counts up by one for each non-knock cycle and is reset in a knock cycle.

This counter A is a predetermined value A0 (for example, 30 cycles)
When the ignition timing θC is reached, the corrected ignition timing θC is corrected in the advance direction by a predetermined value θ■ (for example, 0.5° CA) (θc=θ
c-θ■). Therefore, in this dormitory example, the advance angle adjustment during steady state is performed by 0.5° CA every 30 cycles y. Note that the correction ignition timing θC is prevented from becoming negative in the same way as in the case of acceleration. In the case of a non-knock cycle, the ignition timing θ is corrected in the advance direction as described above.

This value (θ=θ, -θc) is then set in a timer and the ignition countdown begins. Thereafter, the value of the cycle count C is incremented by one and the process returns to the main program.

Now, the calculation method in the case of light load will be explained using FIG. If the load is light, set the delay flag and acceleration advance angle flag to O.
By performing FF, the advance angle speed is returned to a small value for steady state. Then, various counters (acceleration advance counter, etc.) are reset or initialized, and the corrected ignition timing θc is set to zero. In this case, the ignition timing θ becomes equal to θ■, resulting in the most advanced state. This is to prevent performance loss due to retardation by quickly bringing the angle to its most advanced state when the load is light. The ignition timing is calculated in two or more ways, and the engine is ignited through the igniter and ignition coil.

FIG. 8 shows the ignition timing control state when the device of the present invention is used. The horizontal axis represents the progress of the ignition cycle, and the vertical axis represents the corrected ignition timing θC (ie, the total retardation amount due to knock control). In the eighth cylinder, 1 is the invention, 2
represents the state of conventional ignition timing control. It also represents a section in the present invention, a steady advance angle section. It can be seen that the present invention returns to the knock limit ignition timing in a steady state more quickly than the conventional system. the result.

The sluggishness during acceleration is eliminated, and a good acceleration ridge can be obtained. Further, since a knock occurs at the end of section b, and then another knock occurs within a predetermined time (at the end of section b'), the advance angle speed returns to the steady state, and as a result, stability in the steady state is also ensured.

Next, FIGS. 9, 10, and 11 show flowcharts of a second embodiment of the present invention. In this second embodiment, this is used as a means to distinguish between acceleration and steady state.

The above-mentioned sum total S of the retard amounts that are continuously retarded without ever being advanced is used. This sum S differs greatly between the steady state and the accelerated state, and is relatively small during the steady state and relatively large during the accelerated state. Therefore, by using this sum S, it is possible to distinguish between acceleration and steady state. The process will be explained below according to the flowchart. After determining whether it was a big knock or not,
The retardation amount Δθ is set depending on the knock intensity. (For example, if there is a small knock, △θ=0.5°CA (crank angle),
For medium knock, Δθ1=1°CA, for large knock, Δθ=1
．． 5° CA). The retardation amount Δθ1 for each knock intensity (for example, Δθ1=0.5°CA, Δθ2=1°CA, Δθ2
=1.5° CA) is stored as a constant in the ROM.

Next, the knock occurrence interval is a predetermined value (for example, 4 cycles)
Find out if it is longer or shorter than. This knock occurrence interval is R
This can be known by reading the value of the cycle counter C allocated in AM. In other words, when a knock occurs, the counter on this software is cleared to 0 and reset to 1.
It functions to count the ignition cycles until the next knock occurs. This counter is programmed to count up (UP) to a predetermined value Cn and hold that value. This is to prevent counter overflow. Now, when the interval between knock occurrences is long, the sum S of the pushing angle amounts that are successively retarded after L7, which never advances the angle, is calculated. On the other hand, if it is short, correct the push angle △θ and then calculate the sum S. If the knock occurrence interval is short, correct the push angle θ by significantly retarding the push angle during acceleration to reduce the knock during acceleration. This is intended to improve the sound deadening effect. For example, by doubling the retardation amount Δθ, the extinction effect during acceleration can be significantly improved.

Then, as in the first embodiment, the total retardation amount from the basic ignition timing, that is, the corrected ignition timing θC is determined (θC=θC
+Δθ). This corrected ignition timing θC has an upper limit value θcmax.
is set to act as a limiter that prevents the angle from being delayed any further. Then, the final ignition timing 0 for the next ignition is calculated as 0=θ■-θC, and that value is set in the ignition timer.

Next, the acceleration advance angle counter AC, which is a counter on the software,
1 Clear the delay counter DC1, steady advance angle counter A, and cycle counter C to 0.

Next, it is checked by the acceleration advance angle flag whether or not the advance angle speed is currently increasing. This acceleration advance angle flag remains ON (ON) only while the advance angle speed is increasing.

If this flag is ON and therefore the advance angle speed is increasing, whether or not a large knock has occurred is determined by whether the large knock flag is ON or OFF.

When ON, the advance angle speed is returned to the small value at steady state. Therefore, the acceleration advance angle flag and the delay flag are turned OFF. If no major knock occurs (major knock flag is OFF)
) determines whether a timer that measures the knock occurrence interval (KT) is shorter than a predetermined time (KT0). This time (KT0) is set to the average knock occurrence interval in steady state (for example, 0.8 seconds). If knocking occurs in a time shorter than this time (KT0), it is determined that the knock limit in steady state has been reached, and the advance angle speed is returned to the small value in steady state. Further, this timer is cleared only when a knock occurs when the advance angle speed is increased; otherwise, the timer is held after counting for a certain period of time (a value greater than KT■). Therefore, since the knock occurrence interval after the first knock occurrence when the advance angle speed increases is measured, the advance angle speed does not take a small value at a steady state at the first knock (when it is smaller than a large knock). If the current knock is the second or subsequent knock when the advance angle speed increases, and the time (KT) from the previous knock occurrence is shorter than a predetermined time (KT0), the advance angle speed is returned to a small value at a steady state. For this purpose, the acceleration advance angle flag and delay flag are turned ON. Also, knock occurrence interval (
When KT) is longer than a predetermined time (KT0), the knock interval timer is cleared (KT=0).

After that, or when the acceleration advance angle flag is OFF, the next step is to check the value of the sum S. The total sum S is the predetermined value S
If the value exceeds 0 (for example, 4° CA), it is determined that acceleration is occurring, and preparations are made to increase the advance angle speed. That is, the delay flag is turned on and then the process returns to the main program.

Next, the calculation method when the current cycle is not a knock cycle will be explained using FIG. 10, although it is almost the same as the first embodiment. In FIG.

First, check whether the acceleration advance angle flag is ON or OFF.

When ON, the acceleration advance angle counter AC is counted up by one in order to perform advance angle operation with a large advance angle brightness for acceleration. This counter AC ranges from 0 to a predetermined value AC0.
This is a software counter that repeatedly counts up to. If AC has not reached the predetermined value AC0 (for example, 2 cycles), the current corrected ignition timing θC is maintained as it is. If A
If C■ has been reached, the counter AC and the sum S are reset to 0 and the predetermined angle θ■■ (
For example, reduce the height by 0.5° CA). Therefore, the ignition timing is corrected by θ■■ in the advance direction. In this case, when knock does not occur and the acceleration advance is continued, in this example, 0.5° CA (θ■
(2) The advance angle is rapidly advanced in increments of 0.5° CA).

Next, if the corrected ignition timing θC becomes negative, set this value to 0.
and turn off the acceleration advance angle flag and delay flag.
Make it F. This prevents the ignition timing from advancing beyond the basic ignition timing θ■, and also prevents the ignition timing from advancing beyond the basic ignition timing θ■ (i.e., the amount of advance due to knock control θC=
This is to return the advance angle speed to a small value in the case of O).

Now, in FIG. 10, when the acceleration advance angle flag is OFF, it is checked whether the delay flag is ON or OFF.

When the delay flag is ON, it is a preparation period for increasing the advance angle speed. In other words, the current corrected ignition timing value is maintained until the delay counter DC reaches a predetermined value DC0 (for example, 4 cycles), and when the delay counter DC reaches the predetermined value DO■, the acceleration advance flag is turned ON.
By turning on the rapid turning flag, the vehicle enters the rapid turning process. Therefore, in the case of this embodiment, the rapid turn starts after a delay of four cycles.

Further, when the delay flag is OFF, a small value for the steady state is used as the advance angle speed. This steady advance angle counter is a steady advance angle counter A. This counter A counts up by one in each non-knock cycle, and is reset in a knock cycle.

This counter A is a predetermined value A0 (for example, 30 cycles)
When the value reaches 0, the counter A and the sum S are reset to 0, and the corrected ignition timing θc is set to a predetermined value θ, (for example, 0
．． 5°CA) Correct in the height advance direction (θC = θC - θ
■). Therefore, in this embodiment, the advance angle correction during steady state is 3.
It is performed by 0.5°cA every 0 cycles. Note that preventing the corrected ignition timing θC from becoming negative is the same as in the case of the advance angle during acceleration. In the case of a non-knock cycle, the ignition timing θ is adjusted in the advance direction as described above.

This value (θ=θ■-θ■) is then set in a timer and the ignition countdown begins. Thereafter, the value of the signal counter C is incremented by one and the process returns to the main program.

Note that the calculation method in the case of a light load is shown in FIG. 11, and is the same as the first embodiment except that the sum S is reset to 0.

Next, FIGS. 12, 13, and 14 show flowcharts of a third embodiment of the present invention. In this third embodiment, as a means of determining whether the vehicle is accelerating or not, it is determined whether or not the above-mentioned knock occurrence interval is short consecutively. This does not occur continuously when the knock occurrence interval is short during steady state, and when the knock occurrence interval is short during acceleration.

Therefore, whether the vehicle is accelerating or not is determined by whether or not the knock occurrence interval is short. The process will be explained below according to the flowchart. After determining whether or not it is a large knock, a retard amount Δθ is set according to the strength of the knock. (For example, if the knock is small, Δθ=0.5°cA, if the knock is medium, Δθ=1°c
If A large knock, Δθ1.5°cA) Retard amount Δθ1 for each knock intensity (for example, Δθ+1=0.5°cA, Δθ
2=1cA, Δθ2=1.5°cA) are stored as constants in the ROM. Next, it is determined whether the knocking interval is longer or shorter than a predetermined value (for example, 4 cycles). This knock occurrence interval can be known by reading the value of the cycle counter C allocated in the RAM. In other words, the counter on this software functions to count the ignition cycles until knock occurs. This counter counts up (up) to a predetermined value C0.
) and then the programming is done to hold that value. This is to prevent counter overflow.

Next, when the knock occurrence interval is long, the continuous counter CC on the software is reset to 0, and when it is short, the continuous retard amount Δθ is corrected by incrementing the value of the continuous counter CC by one. Here, the continuous counter CC is a counter for determining how many times the knock occurrence interval is short. Furthermore, the reason why the retard amount Δθ is corrected when the knock occurrence interval is short is to greatly retard the angle during acceleration to enhance the effect of eliminating knock during acceleration. For example, by doubling the retardation amount △θ (γ = 23), the extinction effect during acceleration is greatly improved.Next, find the total retardation amount from the basic ignition timing, that is, the linear pressure ignition timing θC. (θc = θc - △θ), an upper limit value θCmax is set for this corrected ignition timing θC, and it acts as a limiter to prevent further retardation.Then, the final ignition timing θ for the next ignition is set to θ =0■-θ■, and set the value in the ignition timer.Next, set the counters on the software: acceleration collapse angle counter AC, delay counter DC, steady advance angle counter A, and cycle counter C. Clear all to 0.

Next, it is checked by the acceleration advance angle flag whether or not the advance angle speed is currently increasing. This acceleration advance angle flag remains ON (ON) only while the advance angle speed is increasing. If this flag is ON and the overload speed is increasing, the large knock flag's O
Judge with N or OFF. When ON, the advance angle speed is returned to the small value at steady state. Therefore, the acceleration overload flag and delay flag are turned OFF. In case 1, when a large knock does not occur (the large knock flag is OFF), the knock occurrence interval (KT
) is shorter than a predetermined time (KT0). The current opening (KT0) is set to the average knock occurrence interval during steady state (for example, 0.8 seconds).

If knocking occurs in a time shorter than this time (TK■), it is determined that the knock limit in steady state has been reached, and the advance angle speed is returned to the small value in steady state. Further, this timer is cleared only when a knock occurs when the angular velocity increases; otherwise, the timer is held after counting for a certain period of time (a value greater than KT■). However, since the interval between knock occurrences after the first knock occurrence when the advance angle speed increases is measured, the first knock (when it is smaller than the large knock)
In this case, the advance angle velocity does not return to the small value at steady state. The current knock is the second or subsequent knock when the advance angle speed increases, and the time (KT) from the previous knock occurrence is the predetermined time (K
T■), the advance angle speed is returned to the small value at steady state. For this purpose, set the acceleration advance angle flag and delay flag to 0FF.
Make it. In addition, the knock occurrence interval (KT) is a predetermined time (KT
0), clear the knock interval timer (K
T=0). After that, or the acceleration corner flag is turned off.
When , the next step is to check the value of the continuous counter CC. Continuity counter CC is set to predetermined value CC0 (CC0≧2)
If this occurs, it is determined that the engine is accelerating because short knock occurrence intervals have occurred continuously, and preparations are made to increase the advance angle speed. That is, the delay flag is turned on and then the process returns to the main program.

Now, the calculation method when the current cycle is not a knock cycle is shown in FIG. 13, but since it is the same as that in FIG. 6, the part between the arms is omitted.

Further, the calculation method in the case of light load is shown in FIG. 14, and is the same as the first embodiment except that the continuous counter CC is reset to 0.

In the above-described embodiment, the retardation amount Δθ per knock is changed depending on the knock intensity and the knock occurrence interval, but it is also possible to change only one of them or not change it at all. However, it is impossible to increase the silencing effect when the pressure is accelerated by changing the retardation amount Δθ in this way.

Further, in the above embodiment, the advance angle counter and the delay counter are counted up as the ignition cycle progresses, but any or all of them may be performed in units of time. For example, the timer 800 shown in FIG.
You can use function 6.

Further, in the above embodiment, the knock occurrence interval when the advance angle speed increases is measured in units of time using a timer, but it can also be measured in units of time as the ignition cycle progresses.

Further, in the above embodiment, the increase in advance angle speed is delayed for a certain period of time before increasing the advance angle speed, but it is not necessarily necessary to delay the increase in advance angle speed. However, it is more effective if it is delayed.

Further, in the above embodiment, the advance angle target value after increasing the advance angle speed is set to the basic ignition timing θ■ (that is, the total retardation due to knock is 0), but θ. Even if the ignition timing (θ■ - β) is retarded by a certain angle β than
−γ).

Alternatively, the past retard amount may be stored in a memory and the stored retard amount may be used as the target ignition timing.

In these cases, if the ignition timing at the time of increasing the advance angle speed is on the advance side than the target ignition timing, if the right angle speed is increased, the knock interval threshold value C■ More fine-grained control can be achieved by changing constants such as the following in accordance with engine conditions such as engine speed and load.

Further, in the above embodiment, the basic ignition timing θ■ is determined from the map in the memory, but it may also be determined by the governor and vacuum advancer in the distributor.

Further, in the above embodiment, the signal after the knock determination by the knock detection circuit is inputted to the microcomputer.

It is also possible to make knock judgments inside the microcomputer. For example, the peak hold signal of the maximum value of the output signal of the knock sensor may be extracted by a peak hold circuit, and the peak hold signal may be A/D converted and input to the microcomputer. In this case, the knock judgment level can be created by numerically averaging the peak hold signal over many cycles.

In addition, in the above embodiment, the number of ignition cycles (or holding time) to maintain the same ignition timing in order to change the advance speed
Although the number of ignition cycles (or holding time) is not changed, the amount of advance per cycle may be changed. (For example, the acceleration advance angle is 3° CA/30 ignition, the steady advance angle is 1° CA/30 ignition, etc.). Of course, it is more effective to change the advance angle speed by changing both the number of ignition cycles to be held (or hold time) and the amount of advance angle per cycle. For the acceleration advance angle, it is better to reduce the number of ignition cycles to be held (or the holding time) and slightly reduce the amount of advance per cycle, so that the acceleration angle reaches the knock limit at steady state more smoothly. Because it connects.

Of course, in any case, the advance angle speed during acceleration must be greater than during steady state. (For example, the advance angle during acceleration is 0.2°cA/1 ignition, and the one angle during steady state is 1°CA/30
like ignition).

Further, in the above embodiment, a microcomputer is used as the control circuit 8, but it can also be constructed from an analog circuit.

For example, a capacitor and a constant current source are used, and the charging and discharging characteristics of the capacitor are used to retard the angle by one angle. In this case, since one angle is performed continuously, the advance angle speed can be changed by changing its slope. That is, by changing the plurality of constant current sources, the charging/discharging characteristics of the capacitor can be changed, and the slope of the advance angle can be changed.

As explained above, in the present invention, the acceleration state is determined according to the knock occurrence status, the advance angle speed is increased, and it is determined whether a steady state has been reached based on the subsequent knock occurrence interval or knock intensity information. Since the advance angle speed is reduced, the advance angle speed is not unnecessarily reduced due to a one-off meter that tends to occur in unstable conditions during transient conditions, ensuring stable drivability during steady state and sluggishness during acceleration. It has an excellent effect of eliminating the problem.

Furthermore, since no special acceleration detector is required, there is an added cost advantage, and there is also the excellent effect of being able to perform stable control unaffected by environmental conditions and changes over time.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing the first embodiment of the present invention, and FIG.
1 is a block diagram of the knock detection circuit in FIG. 1, FIG. 3 is a signal waveform diagram for explaining the operation of the knock detection circuit, and FIG. 4 is a block diagram of the control circuit in FIG. 1. 5, 6, and 7 are flowcharts showing the arithmetic processing procedure in the control circuit, FIG. 8 is a diagram showing the control state of the ignition timing in this embodiment, and FIG. 9. 1O and 11 are flowcharts showing arithmetic processing procedures in a control circuit according to a second embodiment of the present invention, and FIGS. 12, 13, and 14 are flowcharts showing a control circuit according to a third embodiment of the present invention. 15th flowchart showing the arithmetic processing procedure in
The figure is a diagram for explaining the control state of the ignition timing in the second embodiment. 1...Engine, 3...Air flow meter, 5A,
5B...Reference angle sensor and crank angle sensor, respectively. 6... Knock sensor, 7... Knock detection circuit, 8.
...Control circuit including advance angle speed control means, 10...Igniter and ignition coil, 8000...C
P.U. 8001...ROM, 8002...RAM. Representative Patent Attorney Takashi Oka S911 Figure rn 14 t=q

Claims (5)

[Claims] (1) A knock sensor that detects knocking of an internal combustion engine. Ignition timing control for an internal combustion engine, including an ignition timing control means that generates an ignition timing control signal that is advanced or retarded according to the output signal from the knock sensor, and an ignition device that generates an ignition signal based on the ignition timing control signal. In the device, the ignition timing control means determines the acceleration state according to the knock, increases the advance speed of the ignition timing, and when the advance speed is increased, the subsequent ignition timing reaches a predetermined target ignition timing. An internal combustion engine characterized by comprising an advance angle speed control means for reducing the advance angle speed when a knock has previously occurred and the interval between the knock occurrences has become shorter than a predetermined time, or when a knock with a predetermined knock intensity or more has occurred. Ignition timing control device for use. (2) The target ignition timing is an ignition timing retarded by a predetermined value β° crank angle (β≧0) from the most advanced value of the ignition timing determined according to the engine speed and load. An ignition timing control device according to claim 1. (3) The target ignition timing is an ignition timing that is turned by a predetermined value γ° crank angle (γ0) from the ignition timing at the time when the advance angle speed increases. ignition timing control device. (4) The ignition timing control device according to claim 1, wherein the target ignition timing is an ignition timing calculated based on past ignition timings stored in memory. (5) The advance angle speed control means increases the advance angle speed at a point delayed by a predetermined number of cycles or a predetermined time from the time when the knock occurrence interval continues to be shorter than a predetermined value a plurality of times; According to any one of claims 1 to 4, when a knock occurs during a knocking period, the advance angle speed is increased after a delay period occurs again after the knocking ends. Ignition timing control device.