JPH03202661A - Knocking control system - Google Patents

Abstract

PURPOSE:To enable of the precise judgement of knocking by making a knocking judgement by the use of a No.2 knock judging level depending upon whether there is a peak value output within the range of a certain multiple of the No.1 knock judging level obtained from the mean of the peak value output from a knock sensor. CONSTITUTION:While an engine is in operation, a gate signal is given to a signal processing circuit 15 from a processor circuit 13 in a certain knock sensing division, to turn on a gate switch 35. Thereby an output signal of a knock sensor 3 is given to a peak hold circuit 31 through a BPF 33. The peak value output in holding there is fed to the processor circuit 13 in the specified timing via an A/D converter 34. A No.1 judging level is set on the basis of the mean of the peak value output, while A No.2 judging level is set which increases when the peak value output lies within the range of a multiple predetermined by the No.1 judging level, and decreases when the output lies out of the range. The knocking judgement is thus performed by the use of this No.2 judging level.

Description

Detailed Description of the Invention Overview In determining the knock determination level, a first knock determination level is set based on the average value of the peak value output of the knock sensor, and the peak value output is determined by the first knock determination level. A second knock determination level is set that increases when the knock determination level is within a predetermined multiple of the determination level and decreases when it is outside the range, and an actual determination level is set based on this second knock determination level. , performs a knock determination, and when the second determination level is exceeded, it is determined that there is a knock.

As a result, even if relatively large peak value outputs are continuously detected and the first knock determination level becomes large,
Contrary to this, the second knock determination level becomes smaller. In this way, the actual determination level is maintained at a value based on the average value of the peak value output in the non-knock state, regardless of the presence or absence of knock, and highly accurate knock determination is performed.

INDUSTRIAL APPLICATION FIELD The present invention relates to a knock control method suitably implemented in an ignition timing control device for internal combustion engines.

Prior Art In a typical prior art knock control device, the output of a knock sensor is input to a peak hold circuit, the average value of the resulting peak value output is calculated, and this average value is multiplied by a predetermined multiple. is taken as a knock determination level, and when the peak value output exceeds this knock determination level, it is determined that there is a knock and the ignition timing is retarded.

Problems to be Solved by the Invention In the prior art described above, as the peak value output vpeak from the knock sensor increases, the average value bg also increases. This average value bg is, for example, the peak value output vp
When eak is greater than the previous average value b g i-, it is calculated from b g i -++ 1, and the average value b
If it is less than g i-+, it is determined from bgl-11. By updating the average value bg in this manner, the peak value of the frequency distribution of the average value bg becomes close to the peak of the frequency distribution of the peak value output vpeak.

Therefore, from the no-knock state shown in FIG. 8(1), to the moderate knock strength state shown in FIG. 8(2), and further to the high knock strength state shown in FIG. 8(3). 9 (1> to 9).
As shown in 3), the peak value of the frequency distribution of the average value bg shifts to the increasing side.

Along with this, the frequency of this average value bg is set to, for example, twice the peak knock intensity, and
The knock determination levels indicated by reference numerals 11 to 13 in FIG. 8 (3) also shift to the increasing side.

Note that in the shaded areas in FIG. 8(2) and FIG. 8(3), 5 knots have occurred, and originally,
This is a distribution area of knock intensity that should be determined to be a knock.

Therefore, as the average value bg increases as described above, the knock determination level also increases, so the area indicated by the diagonal line cannot be determined to be knocking, and the ignition timing is further advanced. , the peak value output v
peak increases, the average value bg increases, and knock detection cannot be performed, and this vicious cycle is repeated, and the average value bg continues to increase and diverge, making it impossible to perform knock determination. .

An object of the present invention is to maintain the knock determination level at a value based on the average value of the peak value output of the knock sensor in the non-knock state, regardless of the presence or absence of knock, and to perform highly accurate knock determination. The object of the present invention is to provide a knock M control method.

Means for Solving the Problems The present invention sets a first knock determination level based on the average value of the peak value output of the detected knock sensor within a detection period set corresponding to the ignition timing, setting a second knock determination level that increases when the peak value output is within a range of a predetermined multiple of the first knock determination level and decreases when it is outside the range; Further, in the present invention, which is a knock control method characterized in that knock determination is performed using a level, the detected peak value output is VPEAK, and the previous force value of the first knock determination level is Vmean−+
Then, the current value Vmeani is: When VPEAK≧Vmeani−+, V m
eani= V-ean+-+ 1, and when V P E A K < V mean-, V weani= V weani-1-1
Also, the previous value of the second knock judgment level is determined from BQ i−
+, the current value BGi is VPEAK>1.5
When *V*eani, B G 1 =B G
l − (calculated from 1, 1, 5 * Vmeani≧VPEAK≧V me
When an i, B G i = B G i −+ +
1, and when V P E A K < V mean i, it is characterized in that it is found from BGi=BGi-+ 1 .

According to the present invention, in determining the knock determination level, first, the first knock determination is performed based on the average value of the peak value output of the detected knock sensor within the detection interval set corresponding to the ignition timing. Find the level.

That is, for example, if the detected peak value output is VP
EAK, and when the previous value of the first knock determination level is Vmeani-+, the current value Vmeani is V5 when VPEAK≧Vmeani-+.
eani=Vmeani-1+1, and when VPEAK<Vmeani-+, Vmeani=Vmeani,-1.

When the first knock detection level is determined in this way, using the first knock detection level, when the peak value output is within a range of a predetermined multiple of the first knock detection level, the peak value output is increased; A second knock determination level is set that decreases when the outside.

That is, for example, when the previous value of the second knock determination level is BGi-, the current value BGi is: When VPEAK>1.5*Vmeani, B
Determined from G i = B G i −11, 1, 5 * Vmean≧VPEAK≧Vmean
When Vmeani, it is calculated from BGi=BGi-,+1, and when VPEAK<Vmeani, it is calculated from BGi=BGi--1.

Using the second knock detection level obtained in this way, the actual knock detection level is set to, for example, about 2 to 3 times the second knock detection level, and the peak value output exceeds this knock detection level. When this occurs, it is determined that there is knocking, and retard control is performed.

Therefore, even if a relatively large peak value output is continuously detected and the first knock determination level increases, the second knock determination level goes against it and decreases. As a result, the knock determination level can be maintained at a value based on the average value of the peak value output in the non-knock state, regardless of the presence or absence of knock.

Embodiment FIG. 1 is a block diagram showing the electrical configuration of a knock control device W1 according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the structure of an internal combustion engine 2 whose ignition timing is controlled by the knock control device I. It is a diagram. This knock control device l includes a knock sensor 3, an intake pressure sensor 4, a cooling water temperature sensor 5, a crank angle sensor 6, and other sensors such as an intake air temperature sensor 7a, a throttle valve opening sensor 7b, an exhaust temperature sensor 7c ( An ignition signal is derived to the ignition plug 10 via the igniter 9 based on the detection results (hereinafter collectively referred to as reference numeral 7).

Outputs from the sensors 4 to 7 are input from an input interface circuit 11 to a processing circuit 13 via an analog/digital converter 12. Further, the output from the sensor 6 is input to the processing circuit 13 via an input interface circuit 14. Furthermore, the output from the knock sensor 3 is input to the processing circuit 13 after filtering of the knock signal component and peak value detection are performed in a signal processing circuit 15, which will be described later. The knock sensor 3 is realized by, for example, an acceleration sensor, and is fixed to the cylinder block 21 between the internal combustion engines 2.

The processing circuit 13 is realized by, for example, a microcomputer, and includes a built-in memory 16 for storing various control maps, learned values, and the like. This processing circuit 1
Power from a battery 17 is supplied to the power input terminal Vee of No. 3 via a constant voltage circuit 18. The ignition signal from the processing circuit 13 is provided to the igniter 9 via an output interface circuit 19. Furthermore, when the knock control device 1 malfunctions, the processing circuit 13 turns on the warning light 32 via the output interface circuit 19.

The signal processing circuit 15 includes a bandpass filter 33,
It is configured to include a gate switch 35, a peak hold circuit 31, and an analog/digital converter 34. The center frequency of the bandpass filter 33 is selected to be about 7 kHz, so that only the knock signal component is extracted from the output signal of the knock sensor 3.

As shown in FIG. 3 (1) from the gate terminal P1, the processing circuit 13 receives the signals from time tl to t2 and from time t3 to t4.
Gate switch 3 only during the knock detection section WO between
5, and in response to this gate signal, the gate switch 35 becomes conductive. 6. The knock detection period WO
is set to a period in which no ignition signal is derived and is not affected by vibrations caused by opening and closing of the intake and exhaust valves.

When the gate switch 35 is turned on, the output signal of the knock sensor 3 shown in FIG. 3(2) is input to the peak hold circuit 31 via the band pass filter 33.

As a result, the peak hold circuit 31
At time t5., when the reset signal derived from the reset terminal P2 of the terminal P2 and shown in FIG. 3(4) is input. Until t6, the peak value of the output signal from the knock sensor 3 is held as shown in FIG. 3 (3).

The peak value output VPEAK held in the peak hold circuit 31 is generated at, for example, time t7 before the reset signal is output. At timing t8, the signal is digitally converted by the analog/digital converter 34 and read into the processing circuit 13. The processing circuit 13 calculates the average value Vmean, which is the maximum frequency of the peak value output VPEAK, in the following manner.

That is, when the previous average value is Vmeani-+ and the current average value is Vmeani, VPEAK≧
When V meani−+, V meani=
V mean-+ + 1- (1).

When V'P E A K < Va+eani-+, Va+eani=Vmeani-+ 1
=12).

The average value Vmeani obtained in this manner is set as the first knock determination level, and the second knock determination level is determined as follows. When the previous value of this second knock judgment level is BGi-, and the current value is BGi, when VPEAK>1.5*Vmeani, BGi=BGi--1...(3) From demand.

1, 5 *Vmeani≧VPEAK≧V*ea
When ni, B G i = B G i −+ + 1
...Determine from (4).

When V P E A K < V + *eani, it is determined from the third equation.

The frequency distribution of the peak value output VPEAK changes from FIG. 8(1) to FIG. 8(3) as the knock intensity increases.
), the frequency distribution shifts toward the increasing side of the knock intensity, that is, the frequency distribution in the state without knocking is indicated by the reference mark fil in Fig. 4, and the frequency distribution in the state where the knock intensity is large is It is indicated by reference numeral 112.

However, the second knock determination level BGi obtained from the average value Vmeani is
In the frequency distribution of PEAK, among the knock occurrence regions indicated by reference mark A, the region indicated by reference mark At is
As indicated by reference numeral B, this can be considered to be equivalent to moving to the decreasing side of the knock intensity symmetrically to the knock intensity of the maximum frequency indicated by reference numeral Z13.

Therefore, the distribution of the second knock determination level BGi is always stable near the maximum frequency of the peak value output VPEAK in the no-knock state, which is indicated by the reference numeral 111. In this way, the peak value output VPEAK becomes the average value Vmean
When it exceeds 1.5 times i, the second knock determination level BGi is updated to the decreasing side, so 1/2 of the frequency representing the occurrence of knock is moved to the decreasing side of the knock intensity, The increasing side and the decreasing side of knock intensity can be targeted around the vicinity of the maximum frequency indicated by reference numeral Z13.

This allows the actual knock judgment level to be set to the peak value output VP in the non-knock state, regardless of the presence or absence of knock.
The value can be maintained at a value based on the average value of EAK, and a highly accurate knock determination can be performed.

FIG. 5 is a flowchart for explaining the knock determination operation described above. In step n1, the knock sensor 3
The peak value output VPEAK is the previous average value Vmeani
It is determined whether or not the current average value V is greater than or equal to
Meani is required, otherwise step n
In step n2.3, the average value V+*eani is determined based on the second equation, and thus in step n2. Average value Va+e at n3
Once ani is calculated, the process moves to step n4.

At step n4, the average value Vmeani is multiplied by 1.5 and stored in register D. In step n5, it is determined whether the peak value output VPEAK exceeds the stored contents of register D, and if not, the process moves to step n6. In step n6, the peak value output VPE
It is determined whether AK is greater than or equal to the average value Viean1, and if so, the knock determination level BGi is updated in step n7 based on the fourth equation.

When the peak value output VPEAK exceeds the stored contents of the register D in step n5, and in step n6, the peak value output VPEAK exceeds the average value Vmeini.
If the knock determination level BGi is less than the third equation, the knock determination level BGi is updated in step n8 based on the third equation.

The knock determination level BGi updated in step n7 or n8 is multiplied by a constant K, for example 2 to 3, determined corresponding to the rotational speed of the internal combustion engine 2 in step n9,
In this way, the actual knock determination level is determined and stored in register E.

In step nlO, it is determined whether the peak value output VPEAK exceeds the stored contents of register E,
If this is the case, that is, if it is determined that knocking has occurred, then in step nll, the retardation correction term AKNK is
is 1 crank angle (below).

After the knock is incremented and updated, the process moves on to another operation. If not, in step n12, it is determined that there is no knock, and the process moves on to another operation.

FIG. 6 is a flowchart for explaining the operation of calculating the advance angle amount, and this operation is performed during the period in which it is determined that there is no knock in step n12, for example, 0.
．． This is done every 5 seconds. In step m1, the retard correction term AKNK is updated by subtracting 1°CA, and in step m2, it is determined whether the updated retard correction term AKNK is 0 or more, and if not, step m3 Then, after the retard correction term AKNK is reset to O, the process moves to other operations, and if so, moves to the direct function operation.

FIG. 7 is a flowchart for explaining the ignition timing calculation operation. In step S1, the crank angle sensor 6
The basic advance term ABSE is determined from the rotational speed and the intake air flow rate calculated based on the rotational speed of the internal combustion engine 2 detected by the engine 2 and the intake pressure detected by the intake pressure sensor 4.

In step s2, an advance angle correction term ACLD is determined from the coolant temperature detected by the coolant temperature sensor 5. In step S3, the sum of the basic road angle term ABSE obtained in step S1 and the advance angle correction term ACLD obtained in step s2 is calculated and stored in register B as an advance angle amount.

In step s4, from the stored contents of the register B,
The retard angle correction term AKNK obtained in step nil or m3 is subtracted, the final advance angle AOP is calculated, and the operation ends.

Effects of the Invention As described above, according to the present invention, the first knock determination level is determined from the average value of the peak value output of the knock sensor, and the peak value output is within a predetermined multiple range of the first knock determination level. Since the knock detection level is determined using the second knock detection level, which increases when the knock is within the range and decreases when the knock is outside the range, the actual detection level is set to the knock detection level when there is no knock, regardless of whether there is a knock or not. The value can be maintained at a value based on the average value of the peak value output of the sensor, and highly accurate knock determination can be performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the electrical configuration of a knock control device 1 according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of the knock control device 1 and an internal combustion engine 2 related thereto, and FIG.
The figure is a timing chart for explaining the knock detection operation, FIG. 4 is a graph showing the concept of the knock detection level according to the present invention, FIG. 5 is a flow chart for explaining the knock detection operation, and FIG. 6 is a graph for explaining the ignition timing. FIG. 7 is a flowchart for explaining the calculation operation of the advance angle amount, FIG. 7 is a flowchart for explaining the ignition timing calculation operation, FIG. 8 is a graph showing the frequency distribution of the peak value output vpeak of the knock sensor, and FIG. Average value b of the peak value output vpeak
It is a graph showing the frequency distribution of g. DESCRIPTION OF SYMBOLS 1... Knock control device, 2... Internal combustion engine, 3-7.
...Sensor, 10...Spark plug, 13...Processing circuit, 15...Signal processing circuit, 31...Peak hold circuit, 33...Bad pass filter, 35...
gate switch

Claims (1)

[Scope of Claims] (1) A first knock determination level is set based on the average value of the detected peak value output of the knock sensor within a detection period set corresponding to the ignition timing, and the peak setting a second knock determination level that increases when the value output is within a range of a predetermined multiple of the first knock determination level and decreases when it is outside the range; A knock control method is characterized in that a knock determination is performed using a knock determination method. (2) Let the detected peak value output be VPEAK,
The previous value of the first knock determination level is Vmeani
When it is set as ____1, the current value Vmeani is VPE
When AK≧Vmeani_−_1, Vmea
It is calculated from ni=Vmeani_-_1+1, and when VPEAK<Vmeani_-_1, V
Meani=Vmeani_-_1, and the previous value of the second knock judgment level is BGi_-
_1, the current value BGi is VPEAK>1.
When 5*Vmeani, BGi=BGi_-
_1-1, and when 1.5*Vmeani≧VPEAK≧Vmeani, BGi=BGi_-_1+1, and when VPEAK<Vmeani, BGi=B
2. The knock control method according to claim 1, wherein the knock control method is determined from Gi_-_1-1.