JPH07113352B2 - Knotting control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention detects the occurrence state of knocking (hereinafter referred to as knock) occurring in an internal combustion engine (engine), and knocks ignition timing, air-fuel ratio, intake pressure, etc. The present invention relates to a knocking control device that controls a control factor (hereinafter referred to as a knocking control system).

[Conventional technology]

In the conventional knock control system, the optimum value of the knock determination level for determining the presence / absence of knock varies depending on the variation of the engine / knock sensor, so that there is a problem that the knocking noise during control greatly varies from vehicle to vehicle. In order to solve this problem, the present inventors have already disclosed in Japanese Patent Laid-Open No. 60-243369 a method and apparatus for automatically correcting the knock determination level in an appropriate direction.

[Problems to be solved by the invention]

By the way, in this kind of thing, knock judgment level V _ref
Is generally made by multiplying an amount that changes according to the knock sensor signal (for example, the median value V ₅₀ of the knock intensity value V) by a fitting constant K (adding an offset value θ _s , V _ref = V ₅₀ × K + θ _s ), and the automatic correction of the determination level is performed by correcting the adaptation constant K.

However, in this conventional method, the amount (for example, V ₅₀ ) that changes in response to the knock sensor signal becomes the second value in the low speed rotation range.
As shown in the figure, the judgment level V _ref = V ₅₀
Even if the K value of × K is modified, the determination level itself is hardly modified, so that no matter how many K values are modified, the target knocking state cannot be reached.

Further, if the correction amount of the K value per one time is increased as a countermeasure against the low speed rotation range, the resolution is insufficient in the high speed rotation range, which causes problems of hunting at the determination level and variation of knocking sound. There is a problem of coming.

Then, this invention aims at solving the said problem.

[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 determination level creating means for creating a knock determination level for determining the knock, the knock determination level and the knock determination level Knock determination means for determining knock according to the signal from the knock sensor, control means for controlling the value of the knock control factor according to the result of this knock determination means, and knock determination for determining whether or not the knock determination level is appropriate A case where the level suitability judging means and a judgment level modifying means for modifying the knock judgment level by the judgment level suitability judgment change the multiplying factor K by which the amount of change according to the signal level of the knock sensor is multiplied;
The operation range identifying means is provided for selecting whether the determination level correction means changes the absolute amount determined regardless of the signal level of the knock sensor according to the operation area of the internal combustion engine.

[Action]

As a result, the correction of the determination level by the determination of the appropriateness of the knock determination level appropriateness determining means is changed by multiplying the amount K that changes according to the knock sensor signal level by the magnification K.
The case where the absolute amount determined regardless of the signal level of the knock sensor is changed is selected according to the operating state of the internal combustion engine identified by the operating area identifying 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, 5 is the engine 1 The distributor includes a reference angle sensor 5A for detecting a reference crank angle position (for example, top dead center) and a crank angle sensor 5B for generating an output signal at every constant crank angle of the engine 1. Reference numeral 6 denotes a knock sensor for detecting 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, coil) or the like, and is fixed to the side wall of the engine 1. . Reference numeral 7 denotes a peak hold circuit unit 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. The full-open switch (power switch) 14 for outputting a signal when in the state is output according to whether the air-fuel ratio (A / F) of the exhaust gas is richer or richer than the stoichiometric air-fuel ratio. It is an O ₂ sensor that generates a 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. In FIG. 4, 701 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 for peak-holding the output signal of the knock sensor by, for example, a capacitor.

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 8003 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 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 crank angle position are detected by the timer 8006 and the interrupt control unit 8005 as follows. That is, the CUP8000 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, 1μ
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.

The 8007 is an analog that switches multiple analog signals at appropriate times.
It is a multiplexer for guiding to a 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, a rich signal and a 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 mounts control signals and data signals 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) × V ₅₀ + O _s C where K is a constant written in advance in the ROM 8001 and is a table of engine speed. KC is V
_This is a K value for knock determination level correction that is multiplied by ₅₀ , O ₅ C is for correcting the knock determination level by an absolute amount, and both KC and O _s C are created in step 700. Also this K
C, O _s C are waiting and backed up in a map of engine speed and intake air amount Q / N per engine revolution. V ₅₀ is the median value of the distribution of V, and 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.

Step 400 will be described in detail with reference to the flowchart of FIG.

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.

Step 500 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 V _{50 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) × V ₅₀ Here, A is a cylinder-specific variable created in step 700. D is a predetermined constant, and may have various values as a table of engine speed, Q / N, and the like.

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 V ₅₀ by DV ₅₀ .

If NO in step 5002, the flow advances to step 5008 to determine V <V ₅₀ . Here, if YES is determined, the process proceeds to step 5009 to determine A × V ≦ V ₅₀ .
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 V ₅₀ is reduced by DV ₅₀ . 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, DV ₅₀ is set as follows.

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

Step 600 will be described in detail with reference to the flowchart of FIG.

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 time 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 the state is within the knock control region and is in a steady state.

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

Step 700 will be described in detail with reference to the flowchart of FIG.

When the knock state determination and the determination level correction routine start from step 7001, it is determined in step 7002 whether the knock state is too large, for example, CPHL> 0 or A ≧ A.
_{The maximum value} is obtained. If YES, the process proceeds to step 7003, and if NO, the process proceeds to step 7008. In step 7003, it is judged whether the engine condition at that time is equal to or higher than a predetermined rotation speed, and YE
If S, in step 7004, multiply K ₅₀ by V ₅₀ by a predetermined amount ΔKC
Subtract and reduce the determination level, and proceed to step 7005.
If NO, the determination level is reduced by subtracting the predetermined amount Δθ _s from the absolute amount θ _s C in step 7006, and the process proceeds to step 7007. In step 7008, it is determined whether or not the knocked state is too small, for example, by CPHL <0. If YES, the process proceeds to step 7009, and if NO, the process proceeds to step 7012.
In step 7009, it is determined whether the engine condition at that time is equal to or higher than a predetermined rotation speed. If YES, in step 7010 the constant KC of V ₅₀ is increased to increase the determination level, and then in step 7005
Go to. If NO, the absolute amount θ _s C is increased in step 7011 to increase the determination level, and the process proceeds to step 7007.
Step 7005 is a guard for correcting KC within a predetermined range, step 7007 is a guard for correcting θ _s C within a predetermined range, and then the process proceeds to the next step 7012.

In step 7012, it is determined whether the A flag of the target cylinder is set. If YES, then step 7013
If NO, go to 7014. In step 7013, A is increased by a predetermined amount DA, and in step 7014, A is decreased by a predetermined amount DA. Next, the processing proceeds to step 7015, and after executing guard for correcting A within a predetermined range, step 7016
Then, it is determined whether the processing for all the cylinders is completed. Then, if YES, the process proceeds to step 7017, and if NO, the process of the next cylinder is started from step 6003.

In step 7017, this routine ends.

Step 800 will be described in detail with reference to FIG. When the initialization routine of the knock state detection parameter starts from step 8001, the process proceeds to step 8002 and the CPHL and A flags are cleared. 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.

The determination level in the above-described embodiment is the median value V ₅₀ of the distribution of the knock intensity values V, as shown in step 300 of FIG.
However, it may be an amount that changes according to other knock sensor signal levels (for example, the average value V _{mean of} the sensor signal,
Or the number of pulses of the sensor signal above a predetermined level).

Further, in steps 7003 and 7009 of FIG. 10, the correction of the judgment level (whether θ _s or K) is selected by the predetermined engine speed, but as shown in FIG.
You may select in the engine operating area determined by a dimensional map.

Further, in steps 7002 and 7008 of FIG. 10, the determination of suitability of the determination level is performed by detecting the knock state, but as shown in steps 7002A and 7008A of FIG. 13, the knock intensity is detected to determine the determination level. Correction may be performed, or the knock frequency may be similarly detected to correct the knock determination level.

〔The invention's effect〕

As described above, in the present invention, for example, in the engine operating region where the sensor signal level is small, the determination level is corrected by an absolute amount that is unrelated to the sensor signal, and in the engine operating region where the sensor signal level is large, the sensor signal level is set to the sensor signal level. Since the determination level is modified by K that is multiplied by the amount that changes accordingly, the determination level is appropriately modified in all engine regions, and there is an excellent effect that knocking can be accurately controlled.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram for clarifying the configuration of the device according to the present invention, FIG. 2 is a characteristic diagram showing the relationship between the engine speed and an amount that changes according to a knock sensor signal, and FIG. FIG. 4 is a diagram showing an embodiment of an apparatus for carrying out the present invention, FIG. 4 is a block diagram of the peak hold circuit section in FIG. 3, and FIG.
FIG. 6 is a detailed configuration diagram of a control circuit in the figure, FIG. 6 is a flowchart showing a knock control procedure in the invention, and FIG.
FIGS. 11 to 11 are flowcharts showing steps 400 to 800 in FIG. 6 in more detail, and FIG. 12 is a determination region diagram for determining an operating region for determination level correction in another embodiment of the present invention. 13 is a flow chart of the main part showing another embodiment of step 700 in FIG. 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 (1)

[Claims] 1. A knock sensor for detecting knock of an internal combustion engine, a knock determination level creating means for creating a knock determination level for determining knock, and a knock determination level and a signal from the knock sensor according to the knock determination level. Knock determination means for determining the knock, a control means for controlling the value of the knock control factor according to the knock determination result, a knock determination level suitability determination means for determining whether the knock determination level is appropriate, and this determination The correction of the determination level by the level suitability determination is changed by multiplying the amount K that changes according to the signal level of the knock sensor by a magnification K, and by changing the absolute amount that is determined regardless of the signal level of the knock sensor. Of the internal combustion engine, the operating region identifying means for selecting the operating region according to the operating region of the internal combustion engine. Grayed control device.