JPS59119067A - Abnormality detecting method for knocking controller - Google Patents

Abstract

PURPOSE:To enable to detect an abnormality in a knocking sensor, by supplying a pseudo-knocking signal to a vibration sensor at the time of idling of an engine. CONSTITUTION:In step 89, a predetermined value (e.g., 6) is added to the maximum value PMAX of peak values in a predetermined period of time, and the resultant value is made to be a pseudo-knocking judging level P. In the subsequent step 90, a peak value (a) obtained after a predetermined lapse of time and the pseudo-knocking judging level P are compared with each other, thereby judging whether or not a pseudo-knocking has occurred. Accordingly, an abnormality in the knocking sensor can be detected.

Description

[Detailed description of the invention] The present invention relates to a method for detecting an abnormality in a knocking control device.
Is there an abnormality in the knocking control device that retards the ignition timing by a predetermined amount to prevent knocking when knocking occurs? Concerning how to detect.

Conventional knock control devices are equipped with a vibration sensor (knock sensor) that is attached to the engine body and consists of a microphone that detects engine vibration caused by combustion and outputs an electrical signal corresponding to this vibration. It is constructed by connecting the output end of the sensor to an electronic control circuit such as a microcomputer. Then, in the electronic control circuit, it is determined whether or not the non-king control region is over a predetermined load, and the peak value of the electrical signal is compared with a judgment level obtained by multiplying the background level obtained by integrating the electrical signal by a constant K, and the peak value When the peak value exceeds the determination level, it is determined that knocking has occurred and the ignition timing is retarded by a predetermined amount, and when the peak value is below the determination level, it is determined that knocking has not occurred and the ignition timing is advanced by a predetermined amount. The igniter is controlled based on the calculation result. Note that the ignition timing is retarded by one degree by subtracting the corrected ignition retard amount that is changed in response to knocking from the basic ignition advance determined by the engine speed and load.

However, in the above-mentioned knocking control device, if an abnormality occurs in the knocking sensor, such as wire breakage, sensor deterioration, or poor contact, the knocking state cannot be detected and the knocking may occur even though the engine is knocking. If detection is no longer possible, the ignition timing will be advanced to the maximum, causing severe knocking and ignition.

Therefore, in order to detect an abnormality in the knocking control device as described above, it is necessary to pull out the vacuum hose of the pressure switch installed in the intake manifold or turn on an external switch in order to fully determine whether or not the knocking control area is reached. A method has been proposed in which knocking control is performed when the engine is idle and a pseudo-knocking signal is supplied by hitting the engine block with a hammer. According to this method, the ignition timing is retarded when the knock control device is normal, so use a timing light to check whether the top dead center mark engraved on the engine block and pulley has moved to the retarded side. By visually observing, it is possible to determine whether it is abnormal or normal. In other words, despite supplying a pseudo-knocking signal, when the engine is idling (low engine speed), as shown in Fig. , jmThe determination level is determined by making the constant Kt-larger than in the case of normal knocking control.If the constant K is increased, a knock ground occurs (as shown in B in FIG. 1).

If level b fluctuates, the determination level will fluctuate greatly as shown in A in the figure. There is a problem in that the engine block has to be hit hard.On the other hand, if the constant K is made small in order to reduce fluctuations in the judgment level, the engine speed must be kept at a constant value on the high speed side to avoid false judgments. The problem arises that the ground level needs to be raised, which makes inspection difficult.

The present invention has been made to solve the above problems.When the engine is idle, a judgment level is set based on the peak value within a predetermined time, and a pseudo knocking signal is supplied to the knocking sensor after a predetermined time has elapsed. This is to control knocking.

According to the configuration of the present invention described above, since the determination level is set using the peak value, the peak value can be easily detected even during idling, and the unique effect is that it is possible to obtain the determination level with less fluctuation. is obtained.

Next, FIG. 2 shows an example of an engine to which the present invention is applied. This engine is controlled by an electronic control circuit such as a microcomputer, and as shown in the figure, is equipped with an air meter 2 as an intake air amount sensor downstream of an air cleaner (not shown). The air flow meter 2 is - a conven motion plate 2A rotatably provided in the damping chamber! It consists of a knee compensation motion plate and a potentiometer 2B that detects the opening degree of the two people. Therefore, the amount of intake air is detected based on the voltage output from the potentiometer 2B.

Further, an intake air temperature sensor 4 is provided near the air flow meter 2 to detect the temperature of intake air.

A throttle valve 6 is arranged downstream of the air flow meter 2;

A surge tank 8 is provided. This surge tank 8
The intake manifold 10 is connected to the
A solvent injection valve 12 is disposed to protrude into the intake manifold O. In f-1 manifold)'1
0 is connected to the combustion chamber 14A of the engine body 14, and the combustion chamber 14A of the engine is connected to the exhaust manifold 16.
The engine body 14A is connected to a catalyst connector (not shown) filled with a three-way catalyst via a knocking sensor 187, which is comprised of a microphone or the like and detects engine vibrations caused by combustion. !tE is provided. Note that 2o is a spark plug, 22 is an external switch such as a vacuum hose or idle speed switch for controlling knocking when the engine is idling, and 2
4 is a coolant temperature sensor that detects the engine coolant temperature.

A spark plug 20 attached to the engine body 14 is connected to a distributor 26, and the distributor 26 is connected to an igniter 28. The distributor 26 is provided with a cylinder discrimination sensor 30 and an engine rotation angle sensor 32, each of which includes a pickup fixed to the distributor housing, a jig fixed to the distributor shaft, and a null rotor. This cylinder discrimination sensor 3o outputs a cylinder discrimination signal to an electronic control circuit 34 made up of a microcomputer, etc., every 720 degrees of crank angle, and the engine rotation angle sensor 32 outputs a cylinder discrimination signal, for example, every 30 degrees of crank angle. A reference position signal is output to the electronic control circuit 34.

As shown in FIG. 3, the electronic control circuit 34 includes a random access memory (RAM) 36-read only memory (ROM) 38% central processing unit (CP[J) 40.
Clock (CLOCK) 41, first input/output port 42. Second input/output port 44 - first output port 4
6 and a second output port 48,
M36, ROM3EI CPU40. CLOCK41,
First input/output boat 42, second input/output boat 44. The first output port 46 and the second output port 48 are.

It is connected to a bus 50 such as a data bus or a control bus.

The first input/output boat 42 includes a buffer (not shown) -
Multiplexer 54. Analog-digital (A/D)
Via transducer 56, air flow meter 2. A cooling water temperature sensor 24, an intake air temperature sensor 4, etc. are connected. This multiplexer 54 and A/D converter 56
It is controlled by a control signal outputted from the input/output port 42 of. The second input/output boat 44 includes an external switch 2
2 is connected, and a cylinder discrimination sensor 30 and an engine rotation angle sensor 32 are connected via a waveform shaping circuit 64. The second input/output port 44IC also includes a bandpass filter 60. Peak hold circuit 61. Knocking sensor 18 is connected via channel switching circuit 66 and A/D converter 68. This bandpass filter is connected to a channel switching circuit 66 via an integrating circuit 63'i. This channel switching circuit 66 receives either the output of the peak hold circuit 61 or the output of the integrating circuit 63 (the control signal for inputting to the A/D converter 68 is input to the second input/output port 44). It has been input from υ
Further, a reset signal and a gate signal are inputted to the peak hold circuit 61 from the second input/output port 44 .

Further, the first output port 46 is connected to the igniter 28 via a drive circuit 70, and the second output port 4°8 is connected to the fuel injection valve 12 via a drive circuit 72'i.

The ROM 3 B of the electronic control circuit 34 stores in advance a basic map representing the engine speed and intake air side (or load), basic fuel injection amount, etc., and input from the air flow meter 2. The basic ignition advance angle and the basic fuel injection amount are read based on the signal input from the engine rotation angle sensor 32 and the signal input from the engine rotation angle sensor 32, and each signal including the signals from the cooling water temperature sensor 24 and the intake air temperature sensor 4 As a result, the corrected retard angle and corrected fuel injection amount are added to the basic ignition advance angle and basic fuel injection amount,
Igniter 28 and fuel injection valve 12 are controlled. 0
The air-fuel ratio signal output from the 2-senna 22 car is used for air-fuel ratio control to control the air-fuel ratio of the air-fuel mixture to near the stoichiometric air-fuel ratio.

Next, an embodiment in which the present invention is applied to the engine as described above will be described in detail. In addition, in explaining the present invention in detail, the main routines of fuel injection control, air-fuel ratio control, ignition timing control, etc. are the same as those of the conventional art, and therefore their explanations will be omitted.

FIG. 4 shows a predetermined crank angle (for example, 90° CAB TD
C) shows the interrupt routine that is executed every time.

-A/D converted in step 80 and RAMKg
The stored peak value at=reads from RAM. In step 81, it is determined whether the flag SW when the external switch 22 is on is 1, that is, whether it is set. When the flag sw is off, the maximum value P of the peak value
MAXtO is set (Step 82), a flag F indicating the presence of pseudo knocking is lowered (Step 83), and the count value of a counter is set to TkO, which is incremented by 1 every predetermined time (for example, 4 m5ec) (Step 84). When the flag SW is set, it is determined in step 85 whether or not a predetermined time has elapsed using the count value T. Step 8
The count value 1250 of 5 represents 5sec.

Before the predetermined time has elapsed.

In steps 86 and 87, the peak value a is compared with the maximum value PMAX of the peak values, and the one with the highest value is set as the maximum value PMAX. As a result, the maximum value of the peak values within a predetermined period of time is determined. Then, after a predetermined period of time has elapsed, a pseudo non-king signal is supplied to the knocking sensor.

When it is determined in step 185 that a predetermined period of time has elapsed, it is determined in step 88 whether the pseudo-knocking flag F is down, and if the 7 lag F is up, the process proceeds to step 92, and if the flag F is down, the process proceeds to step 92. Proceed to step 89.

In step 89, the maximum value PM of peak values within a predetermined time is
A predetermined value (for example, 6) is added to AX, and the value is set as the pseudo-knocking determination level P. In the next step 90, the peak value a after a predetermined period of time is compared with the pseudo-knocking determination level P to determine whether pseudo-knocking has occurred. When the peak value a is below the judgment level P, that is, when pseudo-knocking is not detected, the process proceeds to step 92, and when the peak value a exceeds the judgment level, that is, when pseudo-knocking is detected, 7 lags Fi are set in step 91. Proceed to step 92. Step 92 is to prevent the counter from overflowing, and is to prevent the count value T from exceeding a predetermined value.

In the routine shown in FIG. 4 above. pseudo-tsukking signal,
The relationship between the maximum peak value PMAX and the flags SW and F is shown in FIG.

FIG. 6 shows a knocking control routine following the routine of FIG. 4. In step 100, it is determined whether flag F is set, that is, whether pseudo-knocking has been detected. If the flag F is set, in step 103, a predetermined value of sleeve stop retardation value θKVC (for example, 0.4° CA) is added to make a new corrected retardation amount θ;
Proceed to step 104. If the flag F is off, it is determined in step 101 whether or not the count value of a timer TIME, which counts 1 sound during a period during which non-king does not occur, is greater than or equal to a predetermined value. This counter TIME increases the count value by 1 every predetermined time (for example, +m5ec), and the count value at step 101 is 48 m
5ec f is shown. When a predetermined period of time has elapsed without knocking.

In step 102, a predetermined value (for example, 0
．． 08°CA) Use the subtracted value as the new corrected retardation amount θ and proceed to step 104. In other cases, proceed to step 1.
Proceed to 05. In step 104, the counter T I ME
t-clear, and in step 105, the value obtained by subtracting the corrected ignition advance angle θ from the basic ignition advance angle θBA13K determined by the engine speed and load is set as the ignition advance angle θ, and in the next step 106, The igniter is controlled so that it is ignited at an ignition advance angle θ.

With the knocking control described above, when the nonkin/ft1j control device is normal, the ignition timing is controlled to be delayed, and when the knocking control device is abnormal, the ignition timing is controlled to be advanced even though pseudo-knocking has occurred. be done. Therefore, by detecting retardation of the ignition timing using a timing light, it is possible to detect whether or not the knocking control device is abnormal.

Furthermore, in the present invention, by making the amount of retardation from the basic ignition advance angle larger than the amount of retardation in normal knocking control when an abnormality is detected in the knocking control device, it is possible to easily detect the retardation state of the ignition timing. becomes possible. First, abnormality detection can be made easier by making the holding time for holding the retarded state of one ignition timing longer than the normal holding time of the knocking side leg when an abnormality is detected in the knocking control device. Furthermore, by outputting the detection result of pseudo-knocking to a display device such as a voltmeter, a timing light can be made unnecessary.

[Brief explanation of drawings]

Fig. ii is a diagram showing changes in sensor output with respect to engine speed, Fig. 2 is a schematic diagram showing an example of an engine to which the present invention is applied, Fig. 3 is a block diagram of the electronic control circuit in Fig. 2; FIG. 4 is a diagram 61e showing one embodiment of the present invention, FIG. 5 is a diagram showing timing in the previous gC addition embodiment, and FIG. 6 is a flowchart showing an example of the knocking control routine in the embodiment. 18...Knocking sensor, 22...External switch, 34...Electronic control circuit. Agent: Tatsuyuki Unuma (and 2 others) (1st drawing) Jean Tanaka's customization (Fig. 4) Fig. 5 F-11←8-K "1-"

Claims (1)

[Claims] (A vibration sensor that detects engine vibration and outputs a full electric signal corresponding to the engine vibration, and compares the peak value of the electric signal with a determination level to determine whether or not knocking has occurred. To detect an abnormality in the knocking control device, which includes an electronic control circuit that delays ignition timing when knocking occurs and advances ignition timing when knocking does not occur, it is necessary to A method for detecting an abnormality in a knocking control device, wherein a determination level is set based on a gb peak value, and a pseudo knocking signal is supplied to the vibration sensor after a predetermined period of time has elapsed to perform the knocking control as a t% indication.