JPH0759933B2 - Knock control device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a knock control device for an internal combustion engine that detects knock of the internal combustion engine and controls a knock control factor such as ignition timing.

[Conventional technology]

Conventionally, as this type, there has been considered a type in which a knock state is detected based on a distribution shape of intensity values of a knock sensor output to correct a knock determination level (for example, Japanese Patent Laid-Open No. Sho 60).
-243369 publication).

[Problems to be solved by the invention]

Fig. 2 shows the maximum value VPEAK of the knock sensor signal within the specified interval.
The cumulative% distribution when a large number of samples are sampled is plotted on a lognormal probability paper. The distribution (a) when the sensor signal is too small does not output below a certain value due to the characteristics of the signal processing circuit, so that the distribution that should be originally a straight line is broken as shown by the solid line as shown by the broken line. Further, in the distribution (b) when the sensor signal is excessive, since the output is saturated, the original break point shown by the broken line is hidden as shown by the solid line.

In such a situation, there is a problem that the knocking state cannot be accurately detected, and thus the determination level may be corrected in the wrong direction.

Therefore, it is an object of the present invention to prevent correction of the determination level when the knock intensity value becomes too small or too large, and to prevent the determination level from being corrected in the wrong direction.

[Means for solving problems]

Therefore, according to the present invention, as shown in FIG. 1, a knock sensor for detecting knock of the internal combustion engine, a knock intensity value detecting means for detecting a knock intensity value V in a predetermined section from a signal of the knock sensor, and the knock intensity detecting means. The presence or absence of knock is determined by comparing the knock intensity value V and the knock determination level V _ref with a determination level creating means for creating a knock determination level V _ref by multiplying a base value obtained by averaging the intensity values V by a predetermined value. In the knock control device for an internal combustion engine, the knock intensity value V is subjected to multi-cycle sampling in a knock control device including a knock determination means and a drive means for controlling a knock control factor such as an ignition timing or an air-fuel ratio according to the determination result. Knock state detection means for detecting the knock state depending on whether the obtained distribution shape is a predetermined shape or not Then, a knock determination level correction means for correcting the knock determination level by correcting the magnification when the base value is multiplied by a predetermined value so that the distribution shape becomes a predetermined shape, and the knock intensity value V is excessive or excessive. An under- / over-judgment means for judging at least one of the under-corrections, and a correction for prohibiting correction of the magnification according to the determination result of the distribution shape by the judgment level correction means when the knock intensity value V is over- or under-according to the result. Disclosed is a knock control device for an internal combustion engine, which is provided with a prohibiting means.

[Action]

As a result, the knock strength value V
If at least one of the above is judged to be excessive or small, the correction prohibiting means prohibits the correction of the magnification associated with the result of the determination of the distribution shape by the judgment level correcting means.

〔Example〕

The present invention will be described below with reference to embodiments shown in the drawings. FIG. 3 is a block diagram showing an embodiment of the present invention. In FIG. 3, 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 1 and outputs a signal corresponding to this, 4 is a throttle valve,
Reference numeral 5 denotes a distributor having a reference angle sensor 5A for detecting a reference crank angle position (for example, top dead center) of the engine 1 and a crank angle sensor 5B for generating an output signal at every constant crank angle of the engine 1. Reference numeral 6 indicates the vibration of the engine block corresponding to the knock phenomenon of the engine 1 by a piezoelectric element type (piezo element type), an electromagnetic type (magnet,
A knock sensor for detecting by a coil or the like, and a peak hold circuit unit 7 for peak holding the output of the knock sensor for each cylinder. 9 is a water temperature sensor that generates a signal according to the cooling water temperature of the engine, 12 is a fully closed switch (idle switch) for outputting a signal when the throttle valve 4 is fully closed, and 13 is the throttle valve 4 is almost fully opened. A full-open switch (power switch) for outputting a signal when the state is 14 depending on whether the air-fuel ratio (A / F) of the exhaust gas is richer or leaner than the stoichiometric air-fuel ratio. It is an O ₂ sensor that produces an output signal.

8 is an ignition timing control circuit for controlling the ignition timing and the air-fuel ratio of the engine according to the input / output signal states from the respective sensors and switches, and 10 is the ignition timing control signal output from the control circuit 8. They are an igniter and an ignition coil that cut off energization to the ignition coil. The high voltage generated in the ignition coil is applied to the ignition plug of a predetermined cylinder at an appropriate time through the power distribution unit of the distributor 5. Reference numeral 11 is an injector for injecting fuel into the intake manifold based on the fuel injection time (τ) determined by the control circuit 8.

Next, the detailed configuration of the peak hold circuit section 7 will be described with reference to FIG. 701 in FIG. 4 is a filter such as a band pass or a high pass for selecting and extracting only the knock frequency component of the output signal of the knock sensor 6, 702 is an amplifier, 703 is based on the cylinder switching signal from the control circuit 8 It is a peak hold circuit that holds the output signal of the knock sensor by a capacitor or the like.

Next, the detailed configuration and operation of the control circuit 8 will be described with reference to FIG. In FIG. 5, reference numeral 8000 denotes a central processing unit (CPU) for calculating the ignition timing and the fuel injection amount, which uses an 8-bit microprocessor. 8001 is a read-only storage unit (ROM) for storing control programs and control constants necessary for calculation, 8002 is a CPU 8000
Is a temporary storage unit (RAM) for temporarily storing operation data during operation according to a program. Reference numeral 8002 is a waveform shaping circuit for shaping the output signal of the reference angle sensor 5A, and 8003 is a waveform shaping circuit for shaping the output signal of the crank angle sensor 5B.

8005 is an interrupt control unit that causes the CPU 8000 to perform interrupt processing by an external or internal signal, and 8006 is a 16-bit timer configured to increase the counter value by one every clock cycle that is the basic cycle of CPU operation. is there. The engine speed and the Cronck angle position are detected by the timer 8006 and the interrupt control unit 8005 as follows. That is, the CPU 8000 reads the count value of the timer each time an interrupt is generated by the output signal of the reference angle sensor 5A. The count value of the timer is the clock cycle (for example 1 μ
s), the time interval of the reference angle sensor signal, that is, one revolution of the engine, is calculated by calculating the difference between the count value at this interrupt and the count value at the previous interrupt. Time can be measured. In this way, the engine speed is obtained. The crank angle position is determined by the crank angle sensor 5B having a constant crank angle (for example, 30 ° C).
Since it is output every time, the crank angle at that time can be known in units of 30 ° C. based on the top dead center signal of the reference angle sensor 5A. The crank angle signal for every 30 ° C. is used as a reference point for generating the ignition timing control signal and a cylinder switching signal of the peak hold circuit 703.

Reference numeral 8007 is a multiplexer for switching a plurality of analog signals at appropriate times and leading them to an analog-digital converter (A / D converter) 8008, and the switching timing is controlled by a control signal output from the output port 8010. In this embodiment,
An output signal from the peak hold circuit unit 7 of the knock sensor signal as an analog signal, an intake air amount signal from the air flow meter 3 and a water temperature signal from the water temperature sensor 9 are input. 8008 is an A / D converter for converting an analog signal into a digital signal. 8009 is an input port for a digital signal. In this embodiment, an idle signal from the idle switch 12, a power signal from the power switch 13, and a rich / lean signal from the O ₂ sensor 14 are input to this port. It 8010 is an output port for outputting a digital signal. From this output port, an ignition timing control signal for the igniter 10, a fuel injection signal for the injector 11, a cylinder switching signal for the peak hold circuit 7, and a control signal for the multiplexer 11 are output.
Reference numeral 8011 denotes a CPU bus, and the CPU 8000 puts a control signal and a data signal on this bus signal line to control peripheral circuits and send and receive data.

Now that the configuration of the device for implementing the present invention has been described, the content of knock control will be described using the flowchart of FIG.

When the knock control routine is started from step 100, the knock intensity value V is fetched in step 200. The intensity value V is, for example, the maximum peak value in a predetermined section of the knock sensor signal.

In step 300, knock determination level V _ref is created as follows.

V _ref = K × KC × V50 Here, K is a constant written in ROM in advance, and is a table of engine speed. KC is a K value for judgment level correction, and is created in step 700.
Further, it is desirable that this KC also be backed up while waiting in the table of engine speed and intake air amount Q / N per engine revolution. V50 is the median of the distribution of V,
It is created in step 500 for each cylinder.

In step 400, knock determination and retard amount calculation are performed.

In step 500, the knock state detection parameter is updated.

In step 600, it is judged whether the judgment level correction condition is satisfied.

In step 700, the judgment level is corrected.

In step 800, the knock state detection parameter is initialized.

At step 900, the knock control routine ends.

Using the flow chart of FIG. 7, step 40 of FIG.
0 will be described in detail.

When the routine for knock determination and retard amount calculation starts from step 4001, it is determined in step 4002 whether the engine is in the knock control region, and if YES, the process proceeds to step 4003. In step 4003, it is determined whether or not there is a knock based on the magnitude relation between V and V _ref . If YES (V ≧ V _ref ), the process proceeds to step 4004. In step 4004, the retard amount R is increased by the predetermined amount ΔR.

If NO is determined in step 4003, the process proceeds to step 4007, and it is determined whether or not there is no knocking for a predetermined period. If YES, the process proceeds to step 4008, and if NO, the process proceeds to step 4009. In step 4008, the retard amount R is reduced by a predetermined amount ΔR. At step 4009, the retard amount R is guarded within a predetermined range.

If NO in step 4002, the flow advances to step 4010 to set the retard amount R to an initial value RO.

This routine ends at step 4011.

The step 500 in FIG. 6 will be described in detail with reference to FIG.

When the update of the knock state detection parameter is started from step 5001, V fetched this time is V50 in step 5002.
If it is larger than YES, the process proceeds to step 5003 if YES.
In step 5003, the level Vh is created as follows.

Vh = (A + D) × V50 Here, A is a cylinder-specific variable created in step 700. D is a predetermined constant, but may have various values as a table of engine speed and Q / N.

In the next step 5004, Vh is guarded below a predetermined value. Next, the routine proceeds to step 5005, where V ≧ Vh is judged, and if YES, it proceeds to step 5006, and if NO, it proceeds to step 5007. In step 5006, the knock state detection counter CPHL (for each cylinder) is incremented. Then proceed to step 5007,
Increase V50 by DV50.

If NO in step 5002, the flow advances to step 5008 to make a determination of V <V50. Here, if YES is determined, the process proceeds to step 5009 to determine A × V ≦ V50.
If YES is determined here, the process proceeds to step 5010,
Decrement the knock state detection counter CPHL. Next, the process proceeds to step 5011, and V50 is reduced by DV50. Next, the processing proceeds to step 5012, and A of the cylinder currently being processed
Set the flag.

If NO in steps 5008 and 5009, the process advances to step 5013.

In step 5013, DV50 is set as follows.

Next, the routine proceeds to step 5014, where the DV 50 is guarded within a predetermined range. In step 5015, this routine ends.

Using the flowchart of FIG. 9, step 60 of FIG.
0 will be described in detail.

When the routine for determining whether the determination level correction condition is satisfied is started from step 6001, in step 6002, the previous step 6003
It is determined whether or not a predetermined engine has elapsed from the time when the processing of all the subsequent cylinders is completed. If YES, then step 6003
If NO, go to step 900. By doing so, the process of step 6003 is executed every predetermined period.

In step 6003, it is determined whether V50min ≦ V50 ≦ V50max. If YES, the process proceeds to step 6004, and if NO, the process proceeds to step 800. Here, V50min and V50max are constants set in the ROM in advance.

In step 6004, it is judged whether or not it is in the knock control area. If YES, the process proceeds to step 6005, and if NO, step 7010
Go to.

This routine ends in step 6005, and proceeds to step 700.

Using the follow chart in FIG. 10, the steps in FIG.
The 700 will be described in detail. When the judgment level correction routine starts from step 7001, the routine proceeds to step 7002, where it is judged whether or not the knock state is large. For example, when CPHL> 0 or A ≧ Amax, it is determined that the knock state is too large.
If YES, the process proceeds to step 7005, and the determination level is reduced. Specifically, KC is reduced by a predetermined amount DK.

If NO is determined in step 7002, the process proceeds to step 7006, and it is determined whether the knocked state is too small. For example, CP
When HL <0, it is judged that the knocked state is too small. If YES, the process proceeds to step 7008, and the determination level is reduced. Specifically, KC is increased by a predetermined amount DK.

In step 7009, the judgment level is guarded within a predetermined range. Specifically, KC is guarded between KCmin and KCmax. It is desirable to have KCmin and KCmax in a table of engine speed.

In step 7010, it is determined whether the A flag of the target cylinder is set. If YES, then step 7011
If NO, go to 7012. In step 7011, A is increased by a predetermined amount DA, and in step 7012, A is decreased by a predetermined amount DA. Next, the routine proceeds to step 7014, where it is determined whether the processing for all cylinders has been completed. If YES, step 7
If NO in 015, the process for the next cylinder is started from step 6003. In step 7015, this routine ends.

The step 800 of FIG. 6 will be described in detail with reference to FIG. When the knock state detection parameter initialization routine starts from step 8001, the process proceeds to step 8002 and CPHL, A
Clear the flag. Next, the process proceeds to step 8003, and it is determined whether the processing for all cylinders is completed. Then, if YES, the process proceeds to step 8004, and if NO, the process of step 8002 is performed for the next cylinder. In step 8004, this routine ends.

In the embodiment described above, as a condition for permitting the judgment level correction as shown in step 6003 of FIG.
Although ≦ V50 ≦ V50max is set, Vmin ≦ V50 / A and Vh ≦ Vmax may be set. Here, Vmin and Vmax are constants set in advance. In some cases, correction of the determination level may be prohibited only when the knock intensity value is too large or too small.

Further, in the above-described embodiment, the ignition timing is controlled according to the presence / absence of knock, but other knock control factors such as the air-fuel ratio and the boost pressure may be controlled.

〔The invention's effect〕

As described above, according to the present invention, when the knock intensity value becomes excessively large or excessively small, the correction of the magnification due to the determination result of the distribution shape by the determination level correcting means is prohibited, and the knock intensity value V is sampled in multiple cycles. When the knock determination level is corrected so that the distribution shape obtained at times becomes the predetermined distribution shape, the determination level is corrected in the wrong direction when the distribution shape cannot be determined when the knock sensor signal is too large or too small. And an erroneous knock determination due to correction of the determination level in the wrong direction can be prevented.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram for clarifying the configuration of the device according to the present invention, FIGS. 2 (a) and 2 (b) are cumulative% distribution diagrams of the maximum value V of the knock sensor output signal, and FIG. FIG. 4 is a diagram showing an embodiment of an apparatus for carrying out the invention, FIG. 4 is a block diagram of a peak hold circuit section in FIG. 3, and FIG. 5 is a detailed block diagram of a control circuit in FIG. FIG. 7 is a flowchart showing the procedure of knock control in the present invention, and FIGS. 7 to 11 are flowcharts showing the steps 400 to 800 in FIG. 6 in more detail. 1 ... Engine, 5 ... Distributor, 6 ... Knock sensor, 7 ... Peak hold circuit section, 8 ... Ignition timing control circuit, 10 ... Igniter and ignition coil, 70
3 ... Peak hold circuit, 8000 ... Central processing unit, 8
001 ... ROM, 8002 ... RAM.

Claims (3)

[Claims] 1. A knock sensor for detecting knock of an internal combustion engine, a knock intensity value detecting means for detecting a knock intensity value V in a predetermined section from a signal of the knock sensor, and an average of the knock intensity values V. Determination level creating means for creating a knock determination level V _ref by multiplying the base value by a predetermined value, knock determination means for determining the presence or absence of knock by comparing the knock intensity value V with the knock determination level V _ref, and this determination result. In a knock control device having a driving means for controlling a knock control factor such as an ignition timing or an air-fuel ratio, depending on whether the distribution shape obtained when the knock intensity value V is multicycle sampled is a predetermined shape or not. Knocking state detecting means for detecting the knocking state in accordance with the above, and the above-mentioned vector so that the distribution shape becomes a predetermined shape according to the detection result of the average knocking state. A determination level correction means for correcting the knock determination level V _ref by correcting the magnification for a predetermined multiple of the scan values, and under-- excessive determining means for determining at least one of an excessive or too small of the knock intensity value V ,
According to this result, when the knock intensity value V is too large or too small, there is provided a correction prohibiting means for prohibiting the correction of the magnification associated with the determination result of the distribution shape by the determination level correcting means. Knock control device. 2. The knock control device for an internal combustion engine according to claim 1, wherein the base value is a median value of a distribution obtained when the knock intensity value V is subjected to multi-cycle sampling. 3. The internal combustion engine according to claim 1 or 2, wherein the under- or over-judgment means judges at least one of over- or under-knocking of the knock intensity value V based on the base value. Knock control device for engines.