JPS6338686A - Knocking control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To realize a proper knocking state quickly and to reduce frequent occurrence of knocking, torque loss or the like, by changing a feedback gain of knocking control elements in accordance with a knocking state. CONSTITUTION:An ignition timing control circuit 8 takes out knocking intensity values from a signal of a knock sensor 6 through a peak hold circuit 7 and discriminates whether a distribution shape obtained by effecting a multicycle sampling of the intensity values is equal to a prescribed shape. Then, an average knocking state over a plurality of cycles of an engine 1 is sensed in accordance with a result of the discrimination. When a knocking state is excessively large in controlling an ignition timing based on the sensed result, an amount of a delay angle per cycle is increased for quickly delaying an angle. On the contrary, when the knocking state is excessively small, an amount of an advance angle per cycle is increased for advancing the angle quickly.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a knock for an internal combustion engine that controls control factors such as ignition timing, air-fuel ratio, and boost pressure according to the state of occurrence of knock in the internal combustion engine. Regarding the control device.

[Conventional technology]

Conventionally, the state of occurrence of knock can be detected from the distribution shape of the value LOG (V) obtained by logarithmically converting the maximum value V of the knock sensor output signal during engine combustion, and by correcting the knock judgment level based on this. , a method for setting an appropriate knock determination level has been considered (for example, Japanese Patent Laid-Open Publication No. 60-243369 II). First, this basic idea will be explained.

When the maximum value V WAM of a predetermined section of the knock sensor signal is sampled over many cycles and plotted on log-normal probability paper, the results are shown in Figure 2 (al, ( (These are the characteristics of a 2000cc, 6-cylinder internal combustion engine with a supercharger, rotation speed 4000.p, throttle fully open, and the fifth cylinder.) In this way, there is no knocking. Internal combustion engines in general have the characteristic that the time distribution is a straight line, and the distribution of knock occurrences bends depending on the knock frequency.An example of a method for detecting a knock state that utilizes this characteristic. will be explained using Fig. 2. First, the median of the distribution, that is, the cumulative probability 50
% point■,. For, the upper and lower two thresholds ■0, VL
Set.

VH=AXDXVs.

V,=V,. /A Here, A is a variable that is adjusted so that V≦■ occurs with a predetermined frequency, and D is a constant slightly larger than 1. For these two thresholds, let the probabilities of V≧V, V≦VL be Pl and P, respectively.As is clear from Fig. 2, when there is no knock, Ph<Pt, l- At the time of race knock, it becomes Ph#P. Furthermore, if the knock becomes larger than the trace knock, the bending of the distribution becomes larger, and P,>PL. In other words, (i) Ph
<PL, the knock state is too small.

If (+1)Pb #Pt, the knock state is appropriate.

(Mountain) If Ph>p, the knock state is too large.

That will happen. Therefore, a knock state detection counter called PHL is prepared, and this counter is incremented if ■≧Vh, and decremented if V≦VI. If this is done for a predetermined period of time, a knock state can be detected from the magnitude of PHL.

Next, an example of a method for appropriately correcting the knock determination level is not shown. The appropriateness of the knock determination level cannot be determined based only on the knock state. That is, the fact that knocking has not occurred does not necessarily mean that the knock determination level is too low. Even if an appropriate knock detection level is set, for example, if high octane fuel is used, knock will not normally occur. Therefore, because the determination level is too low, it is necessary to identify whether the noise is mistakenly detected as a knock and the ignition timing is retarded more than necessary, causing the knock to occur, or whether the knock is caused by factors such as the fuel. be. Both of these can be distinguished by the frequency of knock determination or the amount of retardation. For example, when the knocking state is too small, if the knocking frequency is high, it can be determined that it is the former, and if it is low, it can be determined that it is the latter. The same idea can be used when the knock condition is too large.

Therefore, (i) if the knocking state is too large and the knocking judgment frequency is small, the knocking judgment level is judged to be too large;
Decrease the knock detection level.

(ii) If the knocking state is too small and the frequency of knocking determination is high, it is determined that the knocking determination level is too low, and the knocking determination level is shifted by a large amount.

The knock determination level may be corrected as follows.

[Problem that the invention seeks to solve]

It is true that by doing this, it is possible to set an appropriate knock detection level by taking into account manufacturing errors in the engine, knock sensor, etc., changes over time, etc., but until the inappropriate knock detection level is corrected to an appropriate value. During this period, an incorrect knock judgment will be made.

Therefore, during this period, there is a problem that the ignition timing may be over-advanced, causing frequent knocking, or conversely, the ignition timing may be over-advanced, leading to torque loss and an increase in exhaust temperature.

Therefore, the present invention aims to quickly achieve an appropriate non-king state, thereby reducing the occurrence of knocking, torque fluctuation, etc.

[Means for solving problems]

Therefore, as shown in FIG. 1, the present invention provides a knock sensor for detecting the knock of an internal combustion engine, a determination level creating means for creating a determination level for determining the knock of the internal combustion engine, and a determination level and the above. a knock determining means for determining knock based on the output signal of the knock sensor; and determining the ignition timing of the internal combustion engine according to the determination result of the knock determining means.
In a knock control device comprising a control means for controlling knock control factors such as air-fuel ratio, the knock intensity value of this signal is determined from the signal of the knock sensor.
a knock intensity value detecting means for extracting the knock intensity value; a distribution shape determining means for determining whether the distribution shape obtained when sampling the knock strength value ■ over multiple cycles is a predetermined distribution shape; knock state detection means for detecting an average knock state over a plurality of cycles according to the knock state; and feedback gain variable means for changing the feed bank gain of the knock control factor according to the detection result of the knock state detection means. Among the features! ! !
, provides an engine knock control device.

[Effect]

As a result, the knock intensity value V is extracted from the signal of the knock sensor by the knock intensity value detecting means, and the distribution shape determining means determines whether the distribution shape obtained when multiple samples of this knock intensity value V are sampled is a predetermined distribution shape or not. The average knock state over a plurality of cycles is detected by the knock state detection means according to the result of the discrimination, and the feedback gain of the knock control factor is changed by the feed hack gain variable means according to the result.

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

FIG. 3 is a configuration diagram showing an embodiment of the present invention.

In FIG. 3, 1 is a 4-cylinder 4-stroke engine, 3 is an air flow meter that detects the intake air amount of the engine, and 5 is a 3HB angle sensor 5 that detects the reference crank angle position (for example, top dead center) of the engine. 8. This is a distributor incorporating 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., and 7 is a peak that holds the output of the knock sensor at its peak. This is the hold circuit section.

8 is an ignition timing control circuit for controlling the ignition timing of the engine according to the state of the human output signal from each sensor; 10
An igniter and an ignition coil receive an ignition timing control signal output from the control circuit 8 and cut off power to the ignition coil. The high voltage generated in the ignition coil is applied to the spark plug of a predetermined cylinder at an appropriate time by the power distribution aha L of the distributor 5.

Next, the detailed configuration of the peak hold circuit section 7 will be explained using FIG. 4. 701 in FIG. 4 is a filter such as a band pass or high pass filter for selecting and extracting only the knock frequency component from the output signal of the knock sensor 6; 702 is an amplifier;
Reference numeral 03 denotes a peak hold circuit that peak-holds the knock sensor signal output from the amplifier 702 in accordance with the signal from the control circuit 8 using, for example, a capacitor.

Next, the detailed configuration and operation of the control circuit 8 will be explained with reference to FIG. In FIG. 5, 8000 is a central processing unit (CPU) that calculates the ignition timing, and uses an 8-bit microprocessor. 8001 is a read-only memory unit (ROM) for storing control programs and control constants necessary for calculations, 8002 is a c
pus o.

O is a temporary storage unit (RAM) for temporarily storing calculation data during operation according to a program. 8003
8004 is a waveform shaping circuit for shaping the output signal of the reference angle sensor 5A, and 8004 is a waveform shaping circuit for shaping the output signal of the crank angle sensor 5B.

8005 is an interrupt control unit for causing the CPU to perform interrupt processing based on external or internal signals, and 8006 is a CPU
This is a 16-bint timer that is configured to increase the count value by one every cock cycle. is detected as follows. That is, each time an interrupt occurs due to the output signal of the reference angle sensor 5A, the CPU reads the count value of the timer. The count value of the timer increases every 3tll clock cycles (for example, 1μs). By calculating the difference between the count value at the time of the current interrupt and the count value at the time of the previous interrupt, the time interval of the reference angle sensor signal, that is, the time required for one revolution of the engine can be measured. The engine rotation speed is determined.The crank angle position is determined based on the top dead center signal of the reference angle sensor 5A, since the signal from the crank angle sensor 5B is output at every fixed crank angle (for example, 30° CA). You can know the crank angle in units of 30° CA.

This crank angle signal every 30° CA is used as a reference point for generating an 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 time is determined by the output port 801.
It is controlled by a control signal output from 0. In this embodiment, the output signal of the knock sensor signal from the peak hold circuit section 7 and the intake air amount signal from the air flow meter 3 are input as analog signals. 8008 is an A/D converter for converting an analog signal into a digital signal. 801O is an output port for outputting digital signals. From this output boat, igniter 1
Ignition timing control signal for 0, peak hold circuit section 7
A control signal for the multiplexer 8007 and a control signal for the multiplexer 8007 are output. 8011 is CPU Hass, C
The PU carries control signals and data signals on this bus signal line to control peripheral circuits and send and receive data.

The configuration of the apparatus for realizing the present invention has been described above, and the embodiments of the present invention will now be described using the flowchart of the sixth cabinet. Step 100 to knockcon 1
~ When the roll routine begins, in step 101, the maximum value of the knock sensor signal in a predetermined section is taken in as the knock intensity value V, for example, by the output of the peak hold circuit section 7. In step 102, the knock judgment level V r
ef, for example, by a constant K, a correction value Kc created in step 104 described later, and a median value VSO of the distribution of the knock intensity value ■, V ref = K X K CX 'J S.

and create. Next, the process advances to step 103, where knock determination and knock control factors are controlled. This step will be explained in detail later. Next, the process proceeds to step 104, in which a knock state is detected and a knock determination level is corrected. This step will also be explained in detail later. Next step 1
The process advances to 05, and the knock control routine ends.

Next, the steno knob 103, which is a feature of the present invention, is attached to the seventh
This will be explained in detail using the flowchart shown in the figure. In step 103-1, it is determined whether the engine is under knock control conditions, and if YES, step 103-1 is performed.
2. If NO, proceed to step 104. Step 10
In 3-2, the knock intensity value ■ is determined as the knock judgment level V, e
It is determined whether knock has occurred by comparing with r, and Y
In the case of ES, the process proceeds to step 103-3, and in the case of No, the process proceeds to step 103-4. In step 103-3, the ignition timing retard IR is increased by R, and a knock flag is set. In step 103-4, it is determined whether a predetermined period of time Ta has elapsed, and if YES, the process proceeds to step 103-5.
If NO, proceed to step 103-6. Step 10
In 3-5, the retard angle iR is canceled by R1. Step 103
-6, it is determined whether the retard amount is larger than the maximum guard value RMAX, and if YES, the process advances to step 103-7 to guard the retard amount; if No, step 103-8
Proceed to. In step 103-8, it is determined whether the retard amount is smaller than the minimum guard value RMIN. If YES, the process proceeds to step 103-9, where the retard amount is guarded.

Next, step 104 will be explained in detail using the flowchart of FIG. In step 104-1, the current knock intensity value ■ is the median value V of the distribution. A determination is made as to whether it is larger, and if YES, the process proceeds to step 104-2; if NO, the process proceeds to step 104-6. In step 104-2, the upper threshold value Vh is determined by the variable A and a number slightly larger than 1, such as V, =AxDxV.

and create. Next, proceed to step 101-3, and ■≧V1
1 is made, and if YES, the process proceeds to step 104-4; if No, the process proceeds to step 104-12. In step 104-4, a knock state detection counter PHL is incremented.

Next, the process proceeds to step 104-5, where the median value VSO of the distribution is increased by a predetermined amount Δ■. In step 104-6, V
<Determine whether V or O, and if YES, step 104
-7, if NO, proceed to step 104-12. In step 104-7, the lower threshold value V, is set as V,=V,. Create /A. Then, go to step 104-8 a,)V≦
vL is determined, and if YES, the process proceeds to step 104-9, and if No, the process proceeds to step 104-11. Step 1
At 04-9, the knock state detection counter PHL is decremented. In step 104-10, the variable A is increased by a predetermined amount of ■Δ8. In step 104-11, the median of the distribution ■.

is decreased by a predetermined amount ΔV. This step 104-1
V by 1. will converge to the median of the distribution.

In step 104-12, it is determined whether the predetermined period Tc has elapsed, and if YES, step.

Step 104-13; if No, step 105;

In step 104-13, variable A is decreased by a predetermined amount ΔA. Through this step and step 104-10, the variables are adjusted, and the frequency of V≦VL is 1 within a predetermined period T.
times. In step 104-14, it is determined whether the engine conditions are such that knock control is to be performed. If YES, proceed to step 104-15; if NO, proceed to step 104-2.
Proceed to step 4. In steps 104-15, it is determined whether the engine is in a steady state, and if YES, step 104
-16; if No, proceed to step 104-24. In step 104-16, it is determined whether the knock state is too large based on the count value of the knock state detection counter PHL, and if YES, that is, P HL >
If it is O, it is determined that the knocking condition is too large, and step 1
The process proceeds to step 04-17, and if No, the process proceeds to step 104-20.

In step 104-17, the predetermined period T is reached. In step 104-18, it is determined whether or not there was a knock determination based on whether the knock flag has been reset. If YES, it can be determined that the knock determination level is too large, so the process proceeds to step 104-18, and the correction value is set to a predetermined amount Δ. Make it smaller only. In step 104-19, the retard amount R, per step is corrected to the basic amount r, so that the retard angle can be quickly retarded.
Set r(to the value added).

In step 104-20, it is determined whether the knocking state is too small, and if YES (PHL<O), step 1
If the answer is No, the process proceeds to step 104-24. In step 104-21, it is determined whether the knock flag is set, and if YES, it can be determined that the knock judgment rail is too small, so the process proceeds to step 104-22, and the correction value is increased by a predetermined amount Δ. do.

In step 104-23, 1
The advance angle IR per step is changed to the basic amount r1 by the correction amount r,
Set to the value plus . In step 104-24 l
Set the advance/retard amount per step to the basic amount. In step 104-25, the knock state detection counter P I
Reset IL and knock flag.

In the above embodiment, if the knock state is too large, 1
Increase the retard amount Rr per step to enable quick retardation (step 104-19); conversely, if the knock state is too small, increase the advance angle IR per step,
Increased the angle so that it can advance quickly (Ste, B1
04-23), it is also effective to do as shown in FIG. FIG. 9 shows only the changed portion of the steps in FIG. 8. Figure 9 (Al is designed to reduce the advance angle IR□ to prevent unnecessary advance angle when the knock condition is too large, and to prevent unnecessary advance angle by reducing the retard angle iR when the knock condition is too small. FIG. 9 (bl): If the knocking state is too large, advance time T3 is lengthened by adding correction time 1. to basic time 1a (step 104-19).
By this, the advance angle speed is slowed down, and if the knocking state is too small, the advance angle time T is shortened (step 104-
23), the advance angle speed is made faster, and when the knock state is appropriate or when the knock state cannot be detected, the advance time is set to T1 (step 1).
01-24).

Of course, these three embodiments (Fig. 6, Fig. 9 (al,
(b)) may be used in combination.

Further, in this embodiment, the amount of retardation of ignition timing is used as a knock control factor, but the air-fuel ratio, boost pressure, etc. may be changed in conjunction with this.

Further, in this embodiment, the maximum value of a predetermined section of the knock sensor signal is used as the knock intensity value, but a value obtained by integrating the knock vibration output, an effective value of the knock vibration output, etc. may be used as the knock intensity value.

〔Effect of the invention〕

As described above, in the present invention, it is possible to quickly realize an appropriate knocking state by changing the feed hack gain of the knock control factor according to the knocking state.
It has the excellent effect of reducing frequent knocks, torque loss, etc. in the low range.

[Brief explanation of the drawing]

Figure 1 is a diagram corresponding to the claims of the present invention, Figure 2 (a)
, tb+ is a cumulative distribution diagram of the logarithmically converted value of the knock sensor output signal, FIG. 3 is a partial cross-sectional configuration diagram showing one embodiment of the device of the present invention, and FIG. 4 is a more detailed diagram of the peak hold circuit section in FIG. 3. 5 is a more detailed block diagram of the ignition timing control circuit shown in FIG. 3, FIG. 6 is a flowchart explaining the operation of the circuit shown in FIG. 5, and FIG. 7 is a step diagram of the circuit shown in FIG. 103, r'f"flTI flowchart, FIG. 8 is a more detailed flowchart of step 104 in FIG. 6, and FIG. 9(a) is a flowchart of step 1 in FIG.
04-19. A flowchart showing another embodiment of 104-23, FIG. 9fb) shows step 104-1 in FIG.
9.104-23.104-2 ii is a flowchart showing still another embodiment. DESCRIPTION OF SYMBOLS 1... Engine, 6... Knock sensor, 7... Peak hold circuit part, 8... Ignition timing control circuit, 80
00...cpu.

Claims (3)

[Claims] (1) A knock sensor for detecting knock of an internal combustion engine, a determination level creation means for creating a determination level for determining knock of the internal combustion engine, and a knock sensor for detecting knock by using this determination level and the output signal of the knock sensor. A knock control device comprising a knock determination means for making a determination, and a control means for controlling knock control factors such as ignition timing and air-fuel ratio of an internal combustion engine according to the determination result of the knock determination means, from the signal of the knock sensor. Knock intensity value V of this signal
a knock intensity value detecting means for extracting the knock intensity value V; a distribution shape determining means for determining whether the distribution shape obtained when the knock strength value V is sampled multiple times is a predetermined distribution shape; and a feedback gain variable means for changing the feedback gain of the knock control factor according to the detection result of the knock state detection means. Knock control device for internal combustion engines. (2) The knock control factor is the ignition timing, and the feedback gain changed by the feedback gain variable means is the retard amount per step for retarding the ignition timing when a knock is determined, and the ignition timing. The internal combustion engine according to claim 1, wherein the internal combustion engine is at least one of an advance time for advancing the ignition timing and an advance amount per step for advancing the ignition timing. knock control device. (3) The judgment level creation means includes judgment level correction means for correcting the judgment level according to the detection result of the knock state detection means.
The knock control device for an internal combustion engine according to item 1 or 2.