JP2508701B2 - Knotting control device for internal combustion engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a knock control device (knock control system) for controlling knock generated in an internal combustion engine.

[Conventional technology]

In the conventional knock control system, the knock determination level for determining the presence or absence of knock is set improperly due to the variation of the engine and the knock sensor, and in order to solve this problem, the present inventors have already disclosed in JP-A-60. −243369
Japanese Patent Publication discloses a method and apparatus for automatically correcting a knock determination level in an appropriate direction by utilizing the statistical property of a knock sensor signal.

[Problems to be solved by the invention]

However, in such a system that corrects the knock determination level by learning, ensuring system safety becomes an important issue. That is, if erroneous learning is performed for some reason, the knocking noise becomes louder, or conversely, an erroneous retardation occurs and the output of the engine is reduced. It is of course necessary to improve the accuracy of learning control so that the probability of such mis-learning becomes sufficiently small,
It is necessary to consider the minimum safety guarantee even if erroneous learning occurs. That is, the knock determination level is erroneously learned toward the lower side, and the torque is reduced due to the erroneous retardation (the knock determination level is too low, so that even a non-knock is misjudged as a knock and the ignition timing is erroneously retarded). It is still good in the case, but the knock determination level is erroneously learned in the direction of high, and the knock determination level becomes too high, and knock detection becomes impossible (even though the knock determination level is too high, it is a knock. If the ignition timing is not retarded because it cannot be judged as a knock), preignition may be induced, which may lead to engine damage, which is a very safety issue. The present invention seeks to solve this.

This will be described with reference to FIG. Figure 13 (a)
Represents the conventional learning method. That is, the knock determination level V _{ref is set} to V _ref = K × V _mean (K is a proportional constant, V _mean
Is a sensor signal average value), and a proportional constant K (hereinafter referred to as K value) is learned from the initial table value within a range of ± ΔK. In such a conventional method, if the upper limit gart side is erroneously learned, it becomes a safety problem. Therefore, according to the present invention, as shown in FIG. 13B, the learning permission amount ΔK _up in the direction of increasing the knock determination level (that is, the direction in which the knock sound increases) decreases the knock determination level (that is, the knock sound decreases , If anything, by making it smaller than the learning permission amount ΔK _down toward the safe side),
It aims to ensure safety.

[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 the knock intensity value V from the signal of the knock sensor, and a knock determination level V _ref are set. Determination level creating means for creating, knock determination means for determining the presence or absence of knock by comparing the knock intensity value V and the knock determination level V _ref, and controlling knock control factors such as ignition timing according to the determination result. Drive means and a decision level learning correction means for making a learning correction of the knock determination level by judging the suitability of the knock determination level, and a learning permission amount in the direction in which the knocking sound of the learning correction means increases in the opposite direction. A knocking control device for an internal combustion engine, comprising: a determination level learning amount control means for limiting the learning permission amount to a value smaller than the learning permission amount.

[Action]

As a result, whether or not the knock determination level is appropriate is determined, and this knock determination level is learned and corrected by the determination level learning correction means, and the learning permission amount in the direction in which the knocking sound of the learning correction means increases is the determination level learning amount limit. It is limited to a value smaller than the learning permission amount in the reverse direction by the means.

〔Example〕

Hereinafter, the present invention will be described with reference to an embodiment shown in the drawings. FIG. 2 is a block diagram showing an embodiment of the present invention. In FIG. 2, 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. 701 in FIG. 3 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. 4, reference numeral 8000 is 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 80
00 is a temporary storage unit (RAM) for temporarily storing the operation data during operation according to the 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.

Reference numeral 8007 is a multiplexer for switching a plurality of analog signals at appropriate times to lead 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 section 7 of the knock sensor 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 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. In this embodiment, an idle signal from the idle switch 12 and a power switch are input to this port.
The power signal from 13 and the rich and lean signals from the O ₂ sensor 14 are input. 8010 is an output port for outputting a digital signal. Igniter from this output port
The ignition timing control signal for 10, the fuel injection signal for the injector 11, the cylinder switching signal for the peak hold circuit 7, and the 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.

The configuration of the device for implementing the present invention has been described above, and the contents of knock control will be described with reference to 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 ₀ + ΔK) × V ₅₀ Here, K ₀ is a constant written in ROM in advance, and is a table of engine speed. This K ₀ becomes the learning initial value of the knock determination level. ΔK is a determination level correction K value (that is, a learning amount), and has positive and negative signs. Therefore, the final K value (= K ₀ + ΔK) can move in the plus direction and the minus direction around the initial value K ₀ . This ΔK is stored and backed up in a RAM area divided into engine condition areas (for example, engine speed and intake air amount Q / N).

Here, the initial value of ΔK may be 0, but it is better to set it to the negative side (that is, the side where the knocking noise is reduced) because the side where the knocking noise is reduced is controlled. This initial value is applied only when the product is shipped. After that, ΔK stored in the backup RAM is turned on by the key switch.
Later used as initial value. Therefore, it seems that the initial value of ΔK is applied only once at the time of product shipment and has no significant meaning, but it is reset when the value of backup RAM is destroyed due to battery removal. This consideration is also important because it can be used as a value. 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 learning correction of the determination level is performed for each engine state classification.

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

At step 900, the knock control routine ends.

Using the flow chart of FIG. 6, the steps of FIG.
The 400 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 4005, 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 4007. In step 4006, the retard amount R is reduced by a predetermined amount ΔR. In step 4007, 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 in FIG. 5 will be described in detail with reference to FIG.

When the update of the knock state detection parameter starts from step 5001, V fetched this time is V in step 5002.
If it is larger than ₅₀ , if YES, the process proceeds to step 5003. 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 . Here, if YES is determined, the process proceeds to step 5010, and the knock state detection counter CPHL is decremented. Next, the process proceeds to step 5011, and V ₅₀ is reduced by DV ₅₀ . Next, proceeding to step 5012, the A flag of the cylinder currently being processed is set.

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.

Next, step 600 of FIG. 5 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, it is checked in step 6002 whether the correction interval of the knock determination level has elapsed. That is, the correction of the knock determination level is executed at predetermined time intervals. If NO, the process branches to step 900 in FIG. 5, but if YES, the process proceeds to the next step 6003. In step 6003, it is checked whether the engine is in a steady state. For example, when the rate of change ΔNe of the engine speed N ₀ is less than or equal to a predetermined value, it may be regarded as steady. If it is determined that the operation is unsteady in step 6003, the knock determination level is not corrected (branch to step 7007 in FIG. 9). Further steps 6004 if considered stationary
Check whether or not the steady state has continued for a predetermined time. If the engine does not continue for a predetermined time, it is determined that the statistical calculation value for determining the suitability of the knock determination level has not reached the steady state even if the engine itself reaches the steady state, and the correction of the knock determination level is prohibited. (Branch to step 7007).

Using the flow chart of FIG. 9, the steps of FIG.
The 700 will be described in detail.

When the judgment level correction routine is started from step 7001, it proceeds to step 7002 to judge whether the knock state is too large (ignition timing due to the fact that the knock level cannot be judged as knock even though the knock level is too high. However, the knocked state becomes too large by not being retarded). For example, when CPHL> 0 or A ≧ A _max , it is determined that the knocked state is too large. Then, in the case of YES, the process proceeds to step 7003, and ΔK corresponding to the engine speed region at that time is reduced by a predetermined amount DK in order to reduce the determination level.

If NO is determined in step 7002, the process proceeds to step 7004, and it is determined whether or not the knock state is too small. The knocked state becomes too small by being too much). For example, when CPHL <0, it is determined that the knocked state is too small. If YES, the process proceeds to step 7005, and in order to increase the determination level, ΔK corresponding to the engine speed region at that time is increased by a predetermined amount DK.

In step 7006, the judgment level is guarded within a predetermined range.

That is, the learning amount ΔK of the K value is set to −ΔK _down ≦ ΔK ≦ +
Guard within the ΔK _up range. Here, ΔK _down is the maximum learning permission amount in the direction of decreasing the knock determination level,
ΔK _up is the maximum learning permission amount in the direction of increasing the knock determination level. In this embodiment, safety is ensured by setting ΔK _up <ΔK _down .

It is desirable to change ΔK _up and ΔK _down for each engine condition. (For example, as shown in FIG. 13 (b), the table of engine speed is used.) Next, in step 7007, it is determined whether or not the A flag of the target cylinder is set. If YES, the process proceeds to step 7008, and if NO, the process proceeds to 7007. In Step 7008, A
Is increased by a predetermined amount DA, and in step 7009, A is decreased by a predetermined amount DA. Next, the routine proceeds to step 7010, where A is guarded within a predetermined range.

The above steps 7002 to 7010 are executed for all cylinders, and this routine ends in step 7011.

Step 800 of FIG. 5 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 CPHL, A
Clear the flag. Next, the process proceeds to step 8003, and it is determined whether the processing for all cylinders is completed. If NO, the process of step 8002 is performed for the next cylinder. If YES, this routine ends in step 8004.

It should be noted that in the above-described embodiment, ΔK _up <ΔK _down is set in all engine speed regions, but the knock determination level becomes too large and engine damage is a concern on the relatively high speed side. Therefore, it is possible to set ΔK _up <ΔK _down only in the high rotation region as shown in FIG.
(C and d regions in FIG. 11).

Further, although the proportional constant K value is used to change the knock determination level in the above-described embodiment, it is also possible to directly learn at the absolute level. In this case, the 12th
As shown in the figure, the upper limit guard may be set closer to the initial value than the lower limit gart.

Further, in FIG. 9, even if the learning correction amounts DK in steps 7003 and 7005 are not the same value, the amount of DK on the side of increasing the determination level in step 7005 is smaller than the amount of DK on the side of decreasing the determination level in step 7003. Alternatively, the rate of change of the DK on the side of increasing the determination level may be slower than the rate of change of the DK on the side of decreasing the determination level to further improve safety.

Further, in the above-described embodiment, the average knock state is detected from the statistical processing of the intensity value of the knock sensor signal, and the suitability of the knock determination level is determined by this. Method is also conceivable (for example, it may be possible based on information such as how the ignition timing moves by knock control, knock determination frequency, etc.), and the present invention can be applied to all learning control at the knock determination level. .

〔The invention's effect〕

As described above, in the present invention, the learning permission amount of the knock determination level in the direction of increasing knock is limited to a value smaller than the learning permission amount in the opposite direction. Prevent undetectable,
It has an excellent effect of preventing engine damage.

[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 diagram showing an embodiment of the device for implementing the present invention, and FIG. 3 is a peak in FIG. FIG. 4 is a block diagram of the hold circuit section, and FIG. 4 is a detailed block diagram of the control circuit in FIG.
FIG. 5 is a flow chart showing a knock control procedure in the present invention, and FIGS. 6 to 10 are flow charts showing concrete examples of steps 400 to 800 in FIG.
FIGS. 12 and 13 are engine speed-knock determination level characteristic diagrams in another embodiment of the device of the present invention, FIG. 13 (a),
(B) is an engine speed-knock determination level characteristic diagram of the conventional device and the device of the present invention. 1 ... Engine, 5 ... Distributor, 6 ... Knock sensor, 7 ... Peak hold circuit section, 8 ... Control circuit, 10
...... Ignitioner and ignition coil, 703 ...... Peak hold circuit, 8000 ...... Central processing unit, 8001 ......
ROM, 802 ... RAM.

 ─────────────────────────────────────────────────── --Continued from the front page (56) References JP 59-224467 (JP, A) JP 60-27834 (JP, A) JP 62-32281 (JP, A)

Claims (1)

(57) [Claims] 1. A knock sensor for detecting knock of an internal combustion engine, and a knock intensity value V from a signal of the knock sensor.
For detecting knock intensity value and knock determination level
Determination level creating means for creating V _ref , knock determination means for determining the presence or absence of knock by comparing the knock intensity value V and the knock determination level V _ref, and knock control of ignition timing etc. according to the determination result. The driving means for controlling the factors, the judgment level learning correction means for judging and correcting the knock judgment level by judging the suitability of the knock judgment level, and the learning permission amount in the direction in which the knocking sound of the learning correction means increases are reversed. A knocking control device for an internal combustion engine, comprising: a judgment level learning amount limiting means for limiting the learning permission amount in a direction to a value smaller than the learning permission amount.