JPH0692785B2 - Knock control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knock control device for a gasoline engine for automobiles and the like, and more particularly to a knock control device that enables accurate knock detection.

[Background of the Invention]

As the demand for higher engine performance has increased, it has become an important requirement to properly suppress knocking (knocking).

Therefore, even in the knock control device, it is necessary to always correctly detect whether or not the knock detecting means is always operating correctly. Therefore, for example, JP-A-57-35159 and JP-A-57-68559. A diagnosis method of the knock detecting means has been proposed in the publications and the like.

By the way, the clearance of the engine, especially the intake / exhaust valve, varies depending on the temperature, the engine vibration level is different, and the correction condition of the knock detection sensitivity depends on the operating condition of the engine. Is required.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and an object thereof is to change the engine vibration level caused by engine aging, change in knock detection sensitivity due to aging of control unit and knock sensor, etc. The object is to provide a knock control device for automatically correcting and controlling.

[Outline of Invention]

In order to achieve this object, the present invention diagnoses and corrects the knock detection level when the engine water temperature, oil temperature, etc. reach a steady level, and changes the intake air flow rate according to the engine manifold pressure change amount. Detect the condition,
When the amount of change within a predetermined time is less than or equal to a set value, it is judged as a steady operation mode, and the detection level is diagnosed and corrected, and the correction is made within one operation period (from start to stop). When the number of times that the knocking detection device determines that a knock has occurred is equal to or greater than the set value during a specific period so that the control is limited to a predetermined number of times, the correction control is performed again, and after the engine is stopped, the corrected result Is provided, and means for resetting the set number of times is provided at the next engine start.

Example of Invention

Hereinafter, a knock control device according to the present invention will be described in detail with reference to the illustrated embodiments.

First, FIG. 1 is a flow chart for explaining the operation in one embodiment of the present invention. Here, an embodiment in which the pressure T _{P of the} engine manifold is detected by a pressure sensor is shown. Instead of the sensor, it is also possible to use the supply and discharge of an intake air flow meter mounted between the air cleaner and the intake manifold. In this case, the symbols in the figure are as follows.

T _P → Q _P (Intake air flow rate) T _P1 → Q _P1 (Previous intake air flow rate) T _P2 → Q _P2 (Current intake air flow rate) The flow chart in FIG. 1 will be described later. Now, the control point of the present invention will be described with reference to FIG. In this embodiment, the case where the number of pulses is used as the reference signal will be described.

In FIG. 2, 103 is a hardware rewrite of the software part, which includes a counter 104, a previous count value 105, a current count value 106, a previous count value and a current count value. Comparator 10 that compares the count values
7, a reference signal unit 108 for inputting the output signal of the comparator 107 as a memory correction signal, and a comparator 109 for comparing the signal of the detection circuit 102 and the signal of the reference signal 108, the ignition timing when the knock occurs in the comparator 109 Outputs a retard signal.

Next, the entire operation will be described in more detail. Detection circuit 10
The output of 2 is input to the counter 104 and the comparator 109, and the other input of the comparator 109 is connected to the reference signal unit 108,
The reference signal for each cylinder (in this example, four cylinders) is compared with the output of the detection circuit 102, and an ignition timing retard signal is output when a knock occurs. On the other hand, the counter 104 advances the specific cylinder and counts the signal of the detection circuit 102 of the advanced cylinder, and the output of the detection circuit 102 of the specific cylinder that is advanced gradually (in this embodiment, (Pulse) and compare the previous count value with the current count value to determine whether the advanced cylinder is knocked or not, and if the current count value suddenly increases compared to the previous count value. It is determined that a knock has occurred in the advanced specific cylinder, and the reference signal (knock detection pulse number) of each cylinder of the reference signal unit 108 is corrected. That is, the reference signal of the reference signal unit 108 is rewritten according to the count value of the advanced specific cylinder.

FIG. 3 shows an ignition timing control portion of the internal combustion engine control device to which the present invention is applied. A central processing unit (hereinafter referred to as CPU) 12 performs digital arithmetic processing of various data including ignition timing of the internal combustion engine. The ROM 14 stores ignition timing control, other control programs, and fixed data. The RAM 16 is a readable / writable storage element. The backup RAM 17 is a RAM that retains memory even when the internal combustion engine is stopped. The CPU 12 uses various sensors (in this embodiment, a notking detection device 30, a crank angle sensor 40, a load sensor 50, a water temperature sensor 60, an oil temperature sensor 70, etc.) via an input / output interface circuit 20. Takes in the signal and, based on this signal, ROM1
Calculate the ignition timing according to the program stored in 4,
An ignition signal IGN is output via the input / output interface circuit 20. The ignition signal IGN is applied to the base of the power transistor 74 via the amplifier 72,
To drive. By shutting off the power transistor 74, an ignition current is generated in the secondary coil of the ignition coil 76.

FIG. 4 shows a specific configuration of a portion of the input / output interface circuit 20 that contributes to ignition timing control. Position pulse signal from crank angle sensor 40 (abbreviated as POS)
Is added to AND circuits 216 and 220. A reference crank angle signal (referred to as REF) from the crank angle sensor 40.
Is the reset terminal of the first counter register 210 and R
S Flip Flop 218 applied to set terminal. First
The counter register 210 starts counting POS based on the rise of REF by the AND circuit 216 and RS flip-flop 218, and outputs the count value to the comparator 206.
The comparator 206 compares the count value of the first counter register with the ignition timing data θ _1g calculated by the CPU 12 and stored in the advance register 202, and when both match, RS
A set pulse is output to the flip-flop 214, and the RS flip-flop 218 is reset. When a set pulse is input to the RS flip-flop 214, the output output is cut off, the power transistor 74 of the ignition system is cut off, and the discharge current is output to the secondary coil of the ignition coil 76.

Next, the power supply start timing of the ignition coil will be described. Second
The counter register 212 of the above starts counting the position pulse POS via the AND circuit 220 based on the set pulse for turning on the RS flip-flop 222 determined by the comparator 206, and outputs the count value to the comparator 208. . The comparator 208 compares this count value with the value calculated by the CPU 12 and stored in the dwell register 204, and when both match, outputs a reset pulse to the RS flip-flop 214 and resets the RS flip-flop 222. In the RS flip-flop 214, an output is generated at the terminal based on the reset pulse, the power transistor 74 is turned on, and energization of the primary coil of the ignition coil 76 is started.

Next, the fetching of the knocking signal KNCKP into the CPU 12 will be described.

The output pulse KNCKP of the knocking detection device 30 is input to the counter register 234, and the number of KNCKP proportional to the intensity of the generated knocking is counted. When the count value of the counter register 234, which is interrupted at the time of completion of the counting, is taken into the CPU 12 via the path 18, the count value of the counter register 234 is cleared by the reset register 238 at the same time. Prepare for the next occurrence of knocking.

The pulse number NP taken into the CPU 12 is data corresponding to the intensity of knocking and is used for calculation of the ignition timing correction amount.

FIG. 5 is a timing chart showing the operation of the circuit shown in FIG. 3 described above. In the figure, A is a reference crank angle signal and B is a position pulse signal. C indicates the counting status of the first counter register 210, and C1 is the set value of the advance register 202. D indicates the output signal of the comparator 206, and the first counter register 210
Indicates that an output is generated when the count value of reaches the set value of the advance register 202. E indicates the counting status of the second counter register 212, and E1 is the set value of the dwell register 204. F is the output of the comparator 208, which is similar to the operation of the comparator 206. G is
The outputs of the comparators 206 and 208, that is, the outputs of the RS flip-flop 214 responding to D and F are shown. H represents the current of the ignition coil 66 that flows in response to this output, and I
Indicates the ignition timing.

Next, FIG. 6 shows a block diagram of the knocking detecting device 30 which responds to the occurrence of knocking and generates a number of pulses KNCKP corresponding to the intensity of the knocking. In the figure, a knocking sensor 401 is composed of a piezoelectric element and converts the knocking vibration of an engine cylinder into an electric signal. The output signal V _{IN of the} knotting sensor 4017 is input to the bandpass filter 403 via the input processing circuit 402. The bandpass filter 403 is provided for efficiently extracting the knocking signal except the parasitic vibration of the engine, and the band width is selected so as to match the frequency of the knocking signal.

2 knotting signals passed through the bandpass filter 403
The system is divided into systems and one system is input as a knock signal to the comparator 409, and one system is half-wave rectified by the half-wave rectification circuit 404 and smoothed by the smoothing circuit 406 and then input to the I / O 410. On the other hand, the comparison signal for comparison with the knock signal is output from the I / O to the comparator 409 through the D / A 412. The comparison signal may be not only a constant but also f (N), f (N, T _P ). In the comparator 409
The comparison signal from the D / A and the knock signal are compared and a knock pulse is output to the I / O 410.

FIG. 7 shows the signal waveform of each part of the block diagram shown in FIG. (1) is the output of the knotting sensor 401, (2) is the output waveform of the input processing circuit 402, and (3) is the output waveform of the bandpass filter 403. This waveform and D / A41
A knock pulse signal KNCP (6) is obtained by comparing the two signals. The bandpass filter output (3) is half-wave rectified ((4)) and smoothed ((5)) before being input to the I / O 410.

FIG. 8 shows the general flow of the ignition timing control system in this embodiment. Interrupt request 600 in FIG.
Occurs, it is determined by the interrupt request analysis processing of the next step 602 whether it is a knock (KNOCK) reference (REF) or a timer interrupt. If it is a timer interrupt (TIMER), AD conversion of the input signal and input of the engine speed (606), calculation of ignition timing and energization time (608), digital input signal processing according to the instructions of the task schedule 604 (610) and each task of the correction processing (612) is executed.

If the result of the interrupt request analysis in step 602 indicates that an interrupt request has occurred due to a knock, a knock signal processing routine is executed in step 615.

This knock signal processing routine is shown in FIG.
At step 901, the contents N _P of the counter register 234 are fetched, and the fetched pulse number N _P is determined at step 90
At 2, it is compared with the set pulse number N _S. If it is equal to or more than the set value, the process proceeds to step 903, and if it is less than the set number, the process proceeds to step 904, and the value of Δθ is set in these steps. In addition,
N _P (I), N _S (I) at step 902 indicates that it is the No. I cylinder. In step 905, it is determined whether or not the fetched pulse N _P (I) is for a specific cylinder that is advancing, and if it is a specific cylinder, the process proceeds to step 906. On the other hand, in step 907, the pulse number of the advanced cylinder is compared with the previous pulse number of the cylinder. As a result of the comparison, if the pulse number increases rapidly, there is a knock in the advanced cylinder, and the difference between the previous and current pulse numbers (increase pulse number) compared is calculated in step 908. Then, in step 909, a knock pulse flag is set to report that the knock has occurred in the specific cylinder that has been advanced.

If the result of step 602 is an interrupt request by the reference signal, the rotation synchronization processing routine is executed in step 616.

In the routine of step 616, the data of the ignition timing at the time of advancing a specific one cylinder is set. That is, θ _adv is added to the ignition timing θ (N, P) determined by the engine speed N and the engine load T _P (step 808 in FIG. 10).

FIG. 9 shows an ignition timing control routine. In step 701, the normal ignition timing θ (N, T _P ) is calculated according to the engine speed N and the load T _P. In step 702, it is determined whether knock control is being performed. If the knock control is being performed, step 703 is used to correct the knock (θ _ig ← θ (N, T _P ) +
θ _KN ). θ _KN is determined in step 903. If the knock control is not being performed, step 704 determines whether or not the mode is to check the knock detection sensitivity. In the check mode, step 706 gradually advances the ignition timing of a specific cylinder to cause a knock. When a knock occurs, the number of knock detection pulses rapidly increases. The knock detection pulse of the other cylinder is corrected according to the number of pulses when this knock occurs.

On the other hand, if the mode is not the check mode in step 704, the advance angle control of the specific cylinder is canceled and the number of knock detection pulses of each cylinder is not corrected.

Next, a description corresponding to steps 704, 705 and 706 will be given with reference to FIG. . Step when not in knock control
At 801, it is determined whether the operating condition of the engine has changed suddenly. If there is a change, the check mode is released in step 811 and the advance correction for knock generation of a specific cylinder is released in step 812, and the number of knock detection pulses for each cylinder that determines the knock detection sensitivity is not corrected in step 813. Use the previous one. If there is no sudden change, proceed to step 802. A change in the operating state of the step 801 is detected by signals from the load sensor 50 and the load switch 80 shown in FIG.

In step 802, it is determined whether or not the check mode is for advancing the specific cylinder. If it is not the check mode, the routine proceeds to step 809, where it is judged if the ignition timing of the advanced cylinder is the normal ignition timing θ _S = θ (N, T _P ). If θ _S ≠ θ (N, T _P ), the advanced specific cylinder is advanced, and step 812 cancels the knocking advance correction. If θ _S = θ (N, T _P ) in step 809, the specific cylinder is not advanced (all cylinders have the same ignition timing), and the check mode is turned on to correct the knock detection sensitivity. . If it is the check mode in step 802, the operation proceeds to step 803.

At step 803, it is determined whether to advance a specific cylinder based on the current engine speed N and the load T _P. Although the advance angle determination rotation speed N _W and the advance angle determination load T _PW of the step 803 are specific values in this embodiment, they can be searched by a map. If the engine speed N and the load T _P cannot satisfy N _W and T _W in step 803, the control for the correction of the knock detection sensitivity cannot be performed, and therefore the process proceeds to step 813. In step 803, for example, the knock detection sensitivity correction in the idle state is not performed. If the engine speed NN _W and the load T _P T _PW are satisfied in step 803, the process proceeds to step 804 to read the knock pulse. In reading the knock pulse of step 804, the pulse numbers of all cylinders before the advance angle of step 808 are stored. In step 805, it is determined whether or not the number of detected knock pulses has rapidly increased (= determination whether or not a knock has occurred). This flag is set at step 909, and the flag is cleared at 910. If the knock pulse flag is not 1, there is no knock, so the ignition timing of the specific cylinder is gradually advanced.

_Let θ _S = θ (N, T _P ) + θ _adv . Although θ _adv is a specific value in this embodiment, it is also possible to retrieve a map value based on the engine speed N ₁ engine load T _P. That is, θ _adv = θ _adv (N, T _P ).

If the knock pulse flag = 1 in step 805 (that is, when a knock occurs), the number of knock pulses in each cylinder (step
The number of pulses read in step 804) is corrected to the number of pulses in step 908, and the corrected number of knock pulses is set as the number of knot detection pulses. It means that the knock pulse correction is made at step 806. In 807, the check mode is turned off because the knock pulse is corrected.

The process of knock detection will be described with reference to FIG. FIG. 12 (1) shows a cylinder, and the number in (2) shows the number of cylinders. That is, 1 indicates the first cylinder, and 3 indicates the third cylinder. Although a specific cylinder is advanced in this embodiment, FIG. 12 shows a case where only the first cylinder is advanced in a 4-cylinder engine.
FIG. 12 BCDE shows the state before the advance of the first cylinder. That is, the 12th
The number in the figure (4) represents the number of knock pulses in the state where no knock occurs before advance. It is 4 shots in the first cylinder, 5 shots in the 3rd cylinder, 3 shots in the 4th cylinder, 2 shots in the 2nd cylinder. It has been detected. The pulse number of each cylinder is read in step 804. In this state, no knock has occurred. When the first cylinder is advanced in accordance with step 808, a knock occurs in the first cylinder and the number of knock detection pulses rapidly increases as indicated by G in FIG. 12 (4). With G, there are 9 shots. Here, the number of pulses to be corrected for each cylinder is ΔN _S = 9−4 = 5. If the knock detection pulse number set value N _S (I) of each cylinder is obtained in step 806 due to occurrence of knock, the first cylinder N _S (1) =
5 + ΔN _S = 9. Hereinafter, the third cylinder N _S (3) = 5 +
ΔN _S = 10, 4th cylinder N _S (4) = 3 + ΔN _S = 8, 2nd
The cylinder N _S (2) = 2 + ΔN _S = 7. Step 806
Then, N _S (1) to N _S (4) are set as the corrected number of knock detection pulses. FIG. 12 (5) is a detailed view of (3) A.

FIG. 13 shows the first of the four cylinders shown in FIG. 11 which is advanced.
Only the cylinder is extracted. Only the first cylinder is gradually advanced to. (2) is the knock signal and BG
The relationship of L is shown, and (3) shows the number of knock detection pulses. Even if the first cylinder is gradually advanced, the number of knock detection pulses does not change at 4 up to. Tsuwari knock has not yet occurred in the first cylinder. The number of knock pulses increases rapidly.

That is, the knock occurs in the first cylinder. Here, the difference 5 between the number 9 of knock detection pulses and the number 4 of pulses before advancement is the correction of the number of knock detection pulses to each cylinder in this case, and the number of knock detection pulses of each cylinder is rewritten.

By the way, the check of knocking detection sensitivity is that the engine starts and the water temperature, oil temperature, etc. are in a steady state (for example, the water temperature 60
℃, oil temperature of 60 ℃), each structural component of the engine (Shaft, spring etc. that determines the valve clearance)
Need to be carried out in a temperature stable state,
Also, the number of checks should not be too large. For example, in one hour or one day of running, a certain one cylinder is advanced several times (when one cylinder is completed, another one cylinder is further executed, and each cylinder is not executed at the same time). Should do

Therefore, this check correction is performed once or twice after the engine is fully warmed up after the engine is started, and after that, the data is not changed until the engine is stopped, and even after the engine is stopped, It is necessary to memorize the corrected judgment level in the battery backed up RAM and prepare for restart. However, after checking the knock determination level, if the frequency of knock correction is extremely high (when the C / V determines that there is a high number of occurrences of knock) under operating conditions in a specific region, or vice versa. If the frequency of knock correction is very low in the load area (when C / V continues to determine that no knock has occurred), perform this knock determination level check at intervals of several seconds or minutes. Is required.

When the knock determination level check is performed when the engine load is stable, the correction error is small. Therefore, for example, it may be performed when the CPU determines that steady operation has been reached. This steady operation condition is, for example, the load T _P
When the change amount of is less than or equal to 500 mmHg for 100 msec, it may be determined as a steady state. In particular, when using a pressure sensor or the like as the load sensor to detect the internal pressure of the engine manifold, there is a response delay of this pressure sensor,
It is absolutely necessary to correct the knock determination level in steady operation (the above-mentioned conditions). However, even when another sensor having a quick response is used, the knock detection sensitivity becomes better as a result when the correction control is performed while the engine is stable.

Further, in this method, since the check is performed only a few times (this is also only one specific quito) during the driving state for several hours, the driver does not feel uncomfortable.

FIG. 14 shows a knock occurrence frequency detecting task in one embodiment of the present invention, and FIG. 15 shows a processing by a knock signal interrupt for that purpose. In FIG. 15, f _n (N, L): Map advance value of n cylinder θ _TR : Total amount of retard angle due to knocking up to now θ _TA : Total amount of advance angle against advance speed up to now θ _KW : This time This is the total amount of delay angle due to knock.

〔The invention's effect〕

As described above, according to the present invention, since the knock detection sensitivity is corrected only when the engine has reached the stable state, or only when the engine has reached the stable state, the knock detection sensitivity can always be kept in the optimum state. The engine performance can be maximized.

Further, according to the present invention, the knock detection sensitivity is corrected only during a predetermined number of times and when necessary in one driving period, so that the driver does not feel uncomfortable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart showing the operation of an embodiment of a knock control device according to the present invention, FIG. 2 is a software conceptual diagram of an embodiment of the present invention, and FIG. A block diagram showing an example of the applied control system, FIG. 4 is a block diagram showing the input / output interface part in FIG. 3, FIG. 5 is a time chart for explaining the operation, and FIG. 6 is a knock detection device. Block diagram, FIG. 7 is a waveform diagram for explaining the operation of FIG. 6, FIG. 8 is an explanatory diagram of the general flow in one embodiment of the present invention, and FIG. 9 is a flow chart showing an ignition timing control routine. Figure 10 shows the flow chart of the knock correction routine,
Fig. 11 is a flowchart for knock interrupt, Figs. 12 and 13 are explanatory diagrams for correcting the knock detection pulse, Fig. 14 is a flowchart for task for detecting frequency of knock occurrence, and Fig. 15 is a flowchart for knock interrupt. Is.

Claims (7)

[Claims] 1. A vibration sensor for detecting a vibration of an internal combustion engine including a knocking vibration, a knocking detection device for discriminating the knocking vibration by comparing an output signal of the sensor with a predetermined level signal, and a knocking detection device for the knocking detection device. A diagnostic means for diagnosing the detection sensitivity of the knocking detection device having an ignition timing control device for controlling the ignition timing based on the output, and a knocking control device for correcting and controlling the knocking detection sensitivity of the knocking detection device based on the diagnostic result. In the above, a means for detecting the end of warming up of the engine is provided, the above diagnosis is performed after the end of warming up of the engine, and the correction control of the knock detection sensitivity is provided with a means for detecting that it has been performed a specific number of times, and it is preset. After reaching the number of times, the correction control is stopped until the engine is stopped, and the knocking detector is knocked for a specific period. When the number of times it is judged to be raw is equal to or more than the set value, the correction control is performed again, and means for holding the corrected result is provided after the engine is stopped, and the set number of times is set again at the next engine start. A knock control device provided with a repairing means. 2. A knock control device as set forth in claim 1, characterized in that the end of warm-up of the engine is judged by an engine cooling water temperature. 3. A knock control device according to claim 1, characterized in that the end of warm-up of the engine is judged by the oil temperature of the engine. 4. The method according to claim 1, wherein a change in the intake air flow rate of the engine over a predetermined time is calculated, and when the change amount is less than or equal to a predetermined value, it is determined that the engine warm-up has ended. A knock control device having the above-mentioned configuration. 5. The device according to claim 1 or 4, further comprising means for detecting that the knock detection level correction control has been performed a specific number of times, and the correction is performed after the preset number of times is reached. A knock control device provided with means for stopping control. 6. The apparatus according to claim 5, further comprising means for holding the corrected result after the engine is stopped and means for resetting the set number of times at the next engine start. A unique knock control device. 7. The knock control according to claim 1, wherein the correction control is performed again when the number of times that the knocking detection device determines that a knock has occurred is a set value or more during a specific period. apparatus.