JPH0689736B2 - Knotting control device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a knocking control device for an internal combustion engine, and more particularly to an electronic engine ignition timing control device for an automobile or the like, which accurately detects knocking occurring in an engine and determines the ignition timing. The present invention relates to a knocking control device for controlling a vehicle.

[Conventional technology]

A conventional knocking control device (for example, JP-A-58-155283)
9), as shown in FIG. 9, a knocking detector 1 for detecting vibrations due to knocking of an internal combustion engine, and only a knocking frequency component (for example, 8 KHz) of a detection signal of the knocking detector 1 is passed. Filter circuit 2, average value output circuit 3-1 that outputs the average value of the detection signal that has passed through the filter circuit 2, determination level generation circuit 3-2 for creating a determination level of knocking based on the value, the detection signal And a knocking determination level are compared with each other to determine whether knocking occurs or not. Each of these circuits is composed of an analog element such as a linear IC, and knocking is detected by an analog method.

[Problems to be solved by the invention]

Therefore, the control content is limited to a specific range even though the circuit configuration is complicated, and it is difficult to apply to complicated control such as controlling the knocking determination signal according to the operating state such as the rotation speed, Consequently, it was difficult to accurately determine knocking.

By the way, as already known,
To some extent, this can be solved by using a digital knock detection device that includes an A / D converter that converts an analog signal into a digital signal and a microcomputer. However, in such a system, an extremely high-speed AD converter capable of finely tracing the waveform of the knocking detection signal is required in order to faithfully AD-convert the detection signal of the knocking detector. However, there is a problem in that the A / D converter is expensive and the cost of the device is increased.

Also, instead of tracing the waveform of the knocking detection signal, a method of performing A / D conversion after sample-holding each peak value of the knocking detection signal is conceivable. In this type of method, an extra peak hold circuit or the like is used. It is necessary to add various means, and the structure is inevitably complicated.

Also, in the digital method using a microcomputer, the knock determination level required to detect knocking is created by multiplying the average value of the knocking detector signal by a predetermined value as in the analog circuit. For this reason, in the transient state of the engine, the follow-up of the determination level is poor, and it is erroneously determined that knocking has occurred, or the transient state immediately after the transient state ends, even though knocking has not occurred. Due to the influence of the state, the determination level is set to a high level, and even if knocking occurs, it cannot be detected. In order to solve such a problem, there is a method of providing an acceleration detecting means other than the above to make an appropriate judgment level (for example, Japanese Patent Laid-Open No. 57-32065), but the cost is increased due to the addition of the acceleration detecting means. There is a problem that becomes large.

Therefore, it is an object of the present invention to provide a knocking control device having a remarkably simple structure, facilitating creation of a determination level, and excellent responsiveness in a transient state, as compared with the related art of this type. .

[Means for solving problems]

In order to achieve the above object, the present invention, as shown in FIG. 1, detects a knocking of an internal combustion engine and corrects the value of a knocking control factor such as ignition timing according to the knocking detection state. In the device, a filter means for passing only a knocking frequency component of the knocking detection signal from the knocking detector, and the knocking detection signal passing through the filter means are given to one of its inputs, and a reference level is applied to the other input. A comparison unit to which a signal indicating the above is given, and a pulse output from the comparison unit is input and the number thereof is counted, and the signal indicating the reference level is set to approximately the center of the knocking detection signal according to the count result. And the knocking is determined from the counting result, and the knocking is determined according to the determination result. Control means for correcting the value of the control factor, counter means for counting how many times the reference level is continuously corrected on the increasing side, and when the count value of the counter means exceeds a predetermined value, the reference A knocking control device for an internal combustion engine, comprising: a reference level increasing means for increasing a level correction amount.

[Action]

As a result, the counter means counts how many times the reference level is continuously corrected to the increasing side, and when the count value of the counter means becomes equal to or more than the predetermined value, it is determined that the vehicle is in the acceleration state and the reference level increasing means. Thus, the correction amount of the reference level is immediately increased so that an appropriate reference level can be obtained even during acceleration.

〔Example〕

Next, an embodiment shown in the drawings will be described in order to clarify the specific configuration and operation of the knocking control device according to the present invention. In FIG. 2, reference numeral 1 is a knocking detector that detects a vibration sound due to engine knocking, 2 is a filter circuit that passes only a predetermined frequency component of the detection signal of the knocking detector 1, and 5 is a detection signal and a micro This is a comparator for comparing the digital signal from the computer 6 with the output signal of the resistance ladder 7 which has been D-A converted.
The microcomputer 6 counts the determination pulses from the comparator 5, sends a signal to the resistance ladder 7 according to the counting result, and sends a signal to the ignition control device 8 including an igniter. It is equipped with a central processing unit (CPU), storage devices (ROM, RAM), input / output devices (I / O), and the like.

The filter circuit 2 is composed of a capacitor and a resistor,
The detection signal from the knocking detector 1 is passed through the filter circuit 2 to remove high-frequency and low-frequency noise components, and only the knocking component of the engine near the frequency of 8 KHz passes.

The microcomputer 6 includes a well-known oscillator circuit 6-2, a power-on-reset circuit 6-3, and a power supply circuit (not shown) as peripheral circuits, and sets the reference position of the engine to an ignition signal from the ignition control device 8 ( The reference position waveform shaping signal (Ne) is received at the interrupt terminal (▲ ▼), the signal is retarded according to the judgment pulse count result, and the output terminal (Ro terminal) outputs the calculated ignition timing signal (igt). Output to the ignition control device 8.

On the other hand, in the microcomputer 6, the output from the comparator 5 that compares the knocking detection signal that has passed through the filter circuit 2 with the output of the resistor ladder 7 that DA converts the digital signal (8 bits) from the microcomputer is input. The comparison result is counted and processed by the central processing unit.

Next, the operation of this embodiment will be described with reference to FIGS. 3 (1) to 3 (4), the reference position signal, which indicates the most advanced angle position, which is determined according to the engine speed and the load shown as the waveform a, is a reference position such as the waveform b by the waveform shaping. The waveform shaping signal Ne is input to the ▲ ▼ terminal of the microcomputer 6 and operation calculation is performed. The knocking detection signal having the waveform c includes the abnormal combustion noise generated in the section τ of the waveform d, that is, in the vicinity of 10 ° C. to 90 ° C. after top dead center (ATDC) with respect to the reference position waveform shaping signal Ne.

4 (1) to (4), the section τ of the waveform d,
That is, for the knocking detection signal (waveform C) between ATDC 10 ° C. and 90 ° C., the D / A conversion value e as the reference level which is almost the center value of the knocking detection signal is output from the microcomputer through the resistance ladder 7. Then, the comparators 5 compare each other and output the determination pulse of the waveform f. Thus, the DA conversion value is increased or decreased according to the count value of the determination pulse f. Here, a method of increasing / decreasing the reference level according to the pulse count value will be described with reference to the flowchart of FIG. The reference level is increased / decreased by calculation of the microcomputer 6.

In FIG. 5, in step 501, it is determined whether or not it is the knock determination section, and if it is not the determination section, the process branches to NO and returns. If it is within the judgment section, branch to YES and go to step 5
At 02, the reference level V _th is output. Here, the reference level V _th to be outputted, and outputs stores the reference level V _th calculated at the end of the previous ignition determination section of the same cylinder. The reference level V _th is represented by a value obtained by dividing 5 V by 8 bits (256), and the minimum unit is LSB = 19.5 mV. This value is determined by the magnitude of the signal output from the knocking detector 1, and it is necessary to change the dynamic range or the resolution depending on the case. In this embodiment,
A value obtained by dividing the above-mentioned dynamic range of 5 V with 8 bits (256) was used as the optimum value.

After outputting the reference level V _th in step 502, step 50
In 3, it is checked whether or not there is a pulse output from the comparator 5, and if there is no output, the flow branches to NO, it is determined in step 505 whether or not the judgment section has ended, and if the judgment section is continuing, It branches to NO and returns to step 503 again. YES when it is determined that there is a pulse in step 503
The pulse counter is incremented by 1 in step 504, the process proceeds to step 505, and if the determination section continues, the process branches again to 503.

Steps 503 to 505 are continued as long as the judgment section continues,
The number of all pulses generated in the judgment section is counted.

When it is determined in step 505 that the determination section has ended, the process branches to YES and proceeds to step 506. In step 506, it is determined whether or not a pulse has occurred even once within the determination section, and if no pulse has occurred once, the flow branches to NO and step 510
Move to.

In step 510, the reference level V _th is decreased by ΔV (19.5 mV), and the process proceeds to step 511. In step 511, the value of the V _th up counter that counts how many times the reference level V _th has continuously increased is cleared. Then, the process proceeds to step 512.

If at least one pulse is counted in the determination section in step 506, the process branches to YES and proceeds to step 507. Step
In 507, it is determined whether to increase or hold the reference level V _th , based on the number of pulses generated in the determination section. In this embodiment, the pulse is held when the pulse is generated only once within the determination section.

Therefore, in the case of holding, the reference level V _th is not updated, and the process proceeds to step 511 to clear the reference level V _th up counter. When the number of pulses generated in the determination section is 2 or more, it is necessary to increase the reference level V _th , so the process proceeds to step 508. In step 508, the reference level V _th is increased by ΔV (19.5 mV). Then, in step 509, the V _th up counter is incremented by 1.

During these steps 506 to 511, the reference level V _th is updated, and the reference level V _th can obtain a level according to the magnitude of the output signal of the knock detector 1.

As described above, when the number of pulses in the judgment section is “0”, the reference level V _th is decreased by ΔV, when the number of pulses is “1” it is held, and when the number of pulses is 2 or more, it is increased by ΔV. By doing so, the level of the reference level V _th is determined by the knock detector 1
It is possible to take the median value when the magnitude of the signal output of is statistically viewed. The median value is a value at which 50% of the signal output exists above and below the median value.

In step 512, it is determined how many times the reference level V _th has continuously increased, and when the reference level V _th has continued for a predetermined number of times (16 times in this embodiment) or more, the reference level V _th is increased again by ΔV in step 513.

As a result, the amount of increase can be doubled when the reference level V _th continuously rises, and the followability of the reference level V _th can be improved. FIG. 6A shows the movement during acceleration when the reference level V _th is manipulated in this way. After rising continuously for a predetermined number of times, the rising rate doubles, and it is possible to follow the output signal of the knocking detector 1 which secondarily increases as shown in FIG. 6 (b).

Steps 514 to 516 are a routine for determining the presence or absence of knocking, and the determination is made based on the number of pulses generated in the determination section. The number of pulses when knocking occurs is the knocking detector 1
Since it is proportional to the duration of the output signal of, it occurs more often than usual. Therefore, it is possible to determine that knocking has occurred when more pulses than the predetermined value N have been generated. In this embodiment, the predetermined value N is set to "18", but this value needs to be set for each engine model.

Therefore, when the number of pulses generated in the determination section is larger than the predetermined value N in step 514, the process proceeds to step 515 and the knock flag is set. If the number of pulses is smaller than the predetermined value N, the process proceeds to step 516 and the knock flag is cleared. The retard amount of the ignition timing is controlled according to the knock flag.

Next, the calculation of the retard amount of the ignition timing will be described using the flowchart of FIG. In step 701, it is checked whether or not the knock flag is set, and if it is set, that is, knock is generated, the process branches to step 702.

In step 702, the advance angle timer ADT that counts time in order to determine the timing for advancing by decreasing the retard amount at regular time intervals from the occurrence of knocking is cleared. This advance timer starts counting again after being cleared.

After that, the routine proceeds to step 703, where the retard amount is calculated.
That is, the retardation amount ΔθR per knock is calculated as the total retardation amount θ.
Add to R. Therefore, the ignition timing is retarded by θR from the basic advance angle to ignite.

At step 704, the total amount of retard angle θR is compared with the maximum amount of retard angle θRmax, and if θR is larger, the process branches to step 705. The maximum retard amount is set in consideration of the rise in exhaust temperature when retarded and the change in knock limit depending on the season.
It is around 10 ° C. In step 705, the total retardation amount θR is reset to the maximum retardation amount and the process is returned.

Next, if the knock flag is not set in step 701, the process branches to step 706. In step 706, it is determined whether or not the value of the retard timer ADT has reached the advance angle setting time AT, and if this advance angle timer ADT is less than the setting time AT, the flow branches to NO and returns.

If the advance timer ADT is longer than the set time AT, the advance timer is cleared. For example, assuming that a set time (for example, 0.4 seconds) has elapsed from the ignition of the last knock occurrence,
The routine branches to step 707 to advance the ignition timing.

In step 707, the advance timer is cleared and the process proceeds to step 708. In step 708, the advance amount Δθ for each set time
A (for example, 0.25 ° C. A) is subtracted from the total retardation amount. Therefore, the ignition timing for the next ignition is advanced by ΔθA for ignition.

Next, the routine proceeds to step 709, where it is judged whether or not θR becomes 0. If it is larger than 0, the routine branches to NO and returns. When it is determined that θR is smaller than 0, the process branches to step 710 to clear θR and return.

As described above, the output signal of the knocking detector 1 is updated by comparing the reference level V _th with the output signal of the knocking detector 1 and updating the reference level to be output next according to the number of pulses output at that time. The median of can be obtained. Further, it becomes possible to detect the occurrence of knocking from the time when the output signal of the knocking detector 1 exceeds the reference level V _th , that is, the magnitude of the pulse number. Further, in a situation where the knocking detection signal continuously rises, such as during acceleration, the tracking performance can be improved by increasing the update of the reference level V _th .

Therefore, since the appropriate reference level V _th is always obtained, knocking can be accurately determined.

Next, the schematic logic of this embodiment is shown in FIGS. 8 (1) to 8 (6).
Shown in. In the figure, the Ne signal (8-1) is counted down (8-
3) and (8-2) are performed, and the operation signal igt indicating the energization timing and ignition timing delayed by a predetermined angle according to the knocking amount
(8-4) is obtained. The actual ignition is performed by the calculation signal igt. Further, a predetermined angle masking (8-6) is performed by a post-ignition timer. The microcomputer 6 calculates the ignition timing and the like during the masking section (8-6). And
After masking, during the first determination section (8-7), the number of knock waveforms exceeding the reference level according to the pulse number, that is, the knock pulse number KNP is obtained.

Then, according to the knock pulse KNP, knock determination is performed as described above, the retard amount is determined, and the reference level is updated as described above (8-8). All operations are controlled by a timer (8-5) initialized by overflow.

〔The invention's effect〕

As described above, the present invention utilizes the fact that the peak value of the signal waveform output from the knocking detector, its duration, and the generation timing carry information necessary for knocking detection. Direct technology A-D
Without conversion, the number of pulses output when the knocking detector signal exceeds the reference level in a predetermined determination section is counted without conversion, and the reference level is set according to the count value of the pulses. While updating, it is possible to determine whether or not knocking has occurred, and by controlling the knocking control factor in accordance with the knocking detection result, it is possible to control to a target knocking sound.

In addition, during acceleration when the knocking detector signal continuously rises, the acceleration state is detected from the movement of the reference level that is updated according to the magnitude of the knocking detector signal, and the update amount of the reference level is automatically changed. As a result, the followability of the reference level can be improved. Therefore, it is possible to determine the acceleration state without using any other means for detecting acceleration, and it is possible to always accurately detect the occurrence of knocking.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention, FIG. 2 is an electric circuit diagram showing an embodiment of the device of the present invention, and FIGS.
FIG. 5 is a signal waveform diagram of a main part of the apparatus shown in FIG. 5, FIG. 5 is a flowchart showing updating of the reference level and calculation of knocking determination in the apparatus shown in FIG.
(B) is a graph showing the movement of the reference level at the time of acceleration in the device shown in FIG. 2 and a graph showing the movement of the peak value of the signal output of the knocking detector. FIG. 7 is a knocking determination result in the device shown in FIG. 8 is a flow chart showing a delay angle calculation based on FIG. 8, FIG. 8 is a timing chart for explaining the operation of the embodiment shown in FIG. 2, and FIG. 9 is a block diagram showing a prior art of a knocking detection system using analog technology. Is. 1 ... knocking detector, 2 ... filter circuit, 5 ... comparator, 6 ... microcomputer, 7 ... resistance ladder, 8 ... ignition control device.

Claims (1)

[Claims] 1. A knocking control device for an internal combustion engine, which detects knocking of an internal combustion engine and corrects a value of a knocking control factor such as ignition timing according to the knocking detection state, wherein a knocking detection signal from a knocking detector is detected. Filter means for allowing only a knocking frequency component to pass, a knocking detection signal passed through the filter means is given to one of its inputs, and a comparator means for giving a signal representing a reference level to the other input; The output pulse is input and the number is counted, and according to the counting result, the signal representing the reference level is increased / decreased so as to be substantially the center value of the knocking detection signal, and knocking is determined from the counting result. And a control means for correcting the value of the knocking control factor according to the determination result, Counter means for counting how many times the quasi-level is continuously corrected on the increasing side; and reference level increasing means for increasing the correction amount of the reference level when the count value of the counter means exceeds a predetermined value. A knocking control device for an internal combustion engine, comprising: