JPH06100172B2 - 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 identifying the presence or absence of knock is set improperly due to variations in the engine and the knock sensor. Japanese Patent Laid-Open No. 243369 discloses a method and apparatus for automatically correcting the knock determination level in an appropriate direction by using the statistical property of a knock sensor signal.

[Problems to be solved by the invention]

In this system, statistical calculations are executed, so basically the knock determination level is allowed to be corrected only in the steady state, but as a result of the subsequent investigation, the engine operating conditions suddenly changed and became post-steady. If it is reached, it has been found that malfunction occurs if correction of the determination level is allowed immediately after reaching steady state. The cause of this malfunction is that the calculated value itself has not reached the steady state value because the statistical calculation is delayed even if the engine reaches the steady state.

The present invention solves this.

[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 to be created, the knock intensity value V, and the knock determination level V
Knock determination means for determining the presence or absence of knock by comparing with _ref , drive means for controlling knock control factors such as ignition timing according to the determination result, steady state for determining whether or not the internal combustion engine is in a steady state A determination means, a knock determination level correction means for correcting the knock determination level when the internal combustion engine is in a steady state based on the statistical calculation result, and a steady state that prohibits the correction of the knock determination level for a predetermined period even after the internal combustion engine reaches the steady state. A knock control device for an internal combustion engine, comprising: a signal delay means.

[Action]

As a result, even if the internal combustion engine reaches the steady state, the knock signal level modification means prohibits the modification of the knock determination level by the steady signal delay means for a predetermined time, and the delay of the statistical calculation in the knock determination level modification means is compensated. .

〔Example〕

The present invention will be described below with reference to the embodiments 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,
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.

Reference numeral 8 is a 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 an ignition timing control signal output from the control circuit 8. These are an igniter and an ignition coil that cut off the power 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 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. 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 8000
Is a primary 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 count 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 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 parallel 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.

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 × 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 flowchart of FIG. 6, 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 4005, and it is determined whether or not there is no knocking for a predetermined period. If YES, the process proceeds to step 4006, 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 is determined in step 4002, the process proceeds to step 4008, and the retard amount R is set to the initial value RO.

In step 4009, this routine ends.

Step 500 in FIG. 5 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.

Next, step 600 of FIG. 5 will be described in detail with reference to the flowchart of FIG. This part is a characteristic part of the present invention.

When the determination routine for determining the determination level correction condition is started from step 6001, it is checked in step 6002 whether the knock determination level correction interval 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. Step 6
At 003, check if the engine is in steady state. For example the rate of change .DELTA.N _e of the engine speed N _e may be so regarded as constant when the predetermined value or less. 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). If it is determined to be steady, it is further checked in step 6004 whether 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).

That is, in FIG. 11, the statistical calculation value (for example, the distribution median value V50 of the sensor signals) shown in FIG. 11 (B) becomes steady from the time a when the engine speed N _e shown in FIG. 11 (A) reaches steady. By prohibiting correction of the knock determination level for a period T (for example, 1 second) until the time point b is reached, it is possible to prevent erroneous determination / correction due to delay in statistical calculation.

Using the flowchart of FIG. 9, step 70 of FIG.
0 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 the knock state is too large. For example, when CPHL> 0 or A ≧ A _max , it is determined that the knocked state is too large. If YES, the process proceeds to step 7003, and the determination level is reduced. For example,
KC is reduced by a predetermined amount ΔK.

If NO is determined in step 7002, the process proceeds to step 7004, 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 7005, and the determination level is increased. For example, KC is increased by a predetermined amount ΔK.

In step 7005, the judgment level is guarded within a predetermined range. For example, guard KC between KCmin and KCmax. this
It is desirable to have KCmin and KCmax in a table of engine speed.

In step 7007, it is determined whether the A flag of the target cylinder is set. If YES, then step 7008
If NO, go 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 knock state detection parameter initialization routine starts from step 8001, the process proceeds to step 8002, and the CPHL, A flag is cleared. 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.

In the embodiment described above, the knock determination level is corrected by the distribution shape of the maximum peak value of the knock sensor signal,
Another intensity value such as an integrated output value in a predetermined section of the knock sensor signal may be used. Further, the present invention can be similarly applied to all of those in which the knock determination level is corrected on the basis of a so-called statistical calculation result, even if it is not the intensity value of the knock sensor signal.

Further, in the above-described embodiment, the correction of the knock determination level is prohibited for a fixed time after the engine condition reaches the steady state, but the ignition cycle is counted and the knock determination level is knocked for a predetermined time corresponding to the number of engine rotations. The determination level correction may be prohibited.

〔The invention's effect〕

As described above, in the present invention, the delay of statistical calculation by the knock determination level correction means can be corrected by prohibiting the correction of the knock determination level for a predetermined time after the engine reaches the steady state, and the engine operation can be performed. Even when the steady state is reached after the condition changes suddenly, there is an excellent effect that it is possible to prevent erroneous correction of the determination level immediately after the steady state is reached.

[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.
(A) and (B) are an engine speed change characteristic diagram and a 50% point change characteristic diagram of a sensor signal corresponding to the engine speed variation characteristic diagram for explaining the operation of the device of the present invention. 1 ... Engine, 5 ... Distributor, 6 ... Knock sensor, 7 ... Peak hold circuit section, 8 ... Control circuit, 10 ... Igniter and ignition coil, 703 ... Peak hold circuit, 8000 ... Central processing unit, 8001 ... ROM, 8002 ... RAM.

Claims (1)

[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
A determination level creating means for creating V _ref , a knock determination means for determining the presence or absence of knock by comparing the knock intensity value V and the knock determination level V _rer, and knock control of ignition timing etc. according to the determination result. Driving means for controlling the factors, steady state determination means for determining whether the internal combustion engine is in a steady state, and knock determination level correction means for correcting the knock determination level during the steady state of the internal combustion engine based on the statistical calculation results, A knock signal control device for an internal combustion engine, comprising: a steady signal delay means for inhibiting correction of the knock determination level for a predetermined period even after the internal combustion engine reaches a steady state.