JPS5929772A - Method of detecting abnormality in knocking control unit - Google Patents

Abstract

PURPOSE:To detect abnormalities by opening for at least a predetermined time a gate for an engine in idling to receive electric signal input and control knocking while giving a psuedoknocking signal to examine the presence of variation of ignition timing. CONSTITUTION:The outputs of an intake air amount sensor 2B, an intake air temperature sensor 4, an O2 sensor 22, a cooling water temperature sensor 24, a cylinder discriminating sensor 30, a rotational frequency sensor 32 and a knocking sensor 18 mounted on respective portions of an engine are applied to the input of CPU 34. CPU 34 controls an ignitor 28 and a fuel injection valve 12 with these inputs. The engine is set to the idling condition, a gate is opened between the top dead center TDC and CA 30 deg. ahead same and an engine body is hammered to produce pseudoknocking sounds so that whether or not ignition timing is retarded is detected by using a timing light. Thus, the operational condition of the unit can be easily inspected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting an abnormality in a knocking control device, and in particular, a method for detecting an abnormality in a knocking detection device used for knocking control that delays ignition timing to prevent the occurrence of knocking when knocking occurs. Concerning how to detect.

It is well known that the so-called knocking phenomenon occurs when an abnormal knocking sound occurs inside the engine while the vehicle is running. Strong knocking occurs when the ignition timing is too advanced in a high load range above a certain value. . This type of knocking causes unpleasant noises, and if the knocking is severe, strong air column vibrations occur within the cylinder, which can cause local abnormal high temperatures within the cylinder and damage the engine. become. However, in the case of slight knocking, even if knocking occurs by advancing the ignition timing, it is possible to improve the fuel efficiency of the vehicle by increasing the combustion efficiency of the engine. Therefore, it is preferable to allow a moderate amount of knocking in order to obtain an operating state at optimum efficiency of the engine. Therefore, in order to optimize engine operating efficiency and keep the knocking sound level below a predetermined level, knocking control is performed in accordance with various conditions.

Such knocking control involves installing several knocking sensors such as microphones in the engine body that detect knocking noise and outputting it as an electrical signal, open a gate for a predetermined period of time at every predetermined crank angle, and input this electrical signal. When the level of the signal exceeds a predetermined level, the ignition timing is delayed, and when the level of the input electrical signal is below the predetermined level, the ignition timing is controlled to be advanced to the maximum advance angle that does not cause knocking. This predetermined level (ma) is determined by multiplying the average value of the electric signal by a constant K. Note that in the light load region, knocking control is unnecessary, so ignition timing control may be performed.

However, knocking sensors, etc. that detect knocking,
If an abnormality occurs such as wire breakage, sensor deterioration, poor contact, or electrical noise superimposed on the sensor wire harness, the knocking condition cannot be detected and the engine may knock. An electrical signal of a predetermined level or higher may not be output, or an electrical signal of a predetermined one level or higher may be output even though the engine is not knocking. In particular, if it is determined that there is no knocking even though the engine is knocking, the ignition timing will advance to the maximum advance state, causing severe engine knocking or plaveing, and in the worst case scenario. However, there are problems in that the spark plug and piston may melt and damage, or the gasket may blow out, causing damage to the engine.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for detecting the outer shrine of a non-king control device that can easily detect an abnormality in a knocking detection device including a knocking sensor.

In order to achieve the above object, the configuration of the present invention is such that when the engine is idling, the gate is opened for a time exceeding the predetermined time to input an electric signal to perform knocking control, and also to supply a pseudo knocking signal to a knocking sensor. , an abnormality in the knocking control device is detected by detecting whether or not the ignition timing is delayed. The knocking control described above retards the ignition timing when the level of the electrical signal output from the knocking sensor exceeds a predetermined level, and advances the ignition timing when the level of the electrical signal is below the predetermined level. In order to perform such knocking control when the engine is idling, for example, a short-circuiting idle speed switch (IS switch) used to stop calculating the ignition timing and fixing it at a desired set angle during idling is turned on. This is done by determining whether or not there is. Furthermore, the pseudo-knocking signal is supplied to the knocking sensor by, for example, hitting the engine body with a hammer. As a result, knocking control is performed when the engine is idle, and if the knocking detection device is normal, the ignition timing is controlled to be delayed by a pseudo-knocking signal.If the knocking detection device is abnormal, a pseudo-knocking signal is sent to the knocking sensor. Even if sand is supplied, the ignition timing cannot be controlled to be delayed, so by detecting whether the ignition timing is delayed, it is possible to detect whether or not the knocking detection device is abnormal. In addition, whether the ignition timing is delayed or not,
Detected using a timing light, etc.

In addition, in the present invention, in order to easily detect a delay in ignition timing, the amount of ignition timing delay when an abnormality is detected by the knocking detection device is set to be larger than the amount of ignition timing delay in knocking control. It is preferable to set the ignition timing delay holding time when the knocking detection device detects an abnormality to be longer than the ignition timing delay holding time in normal knocking control.Also, as mentioned above,
Since the gate opening time is set longer than in the case of normal knocking control, there is a risk that noise such as pulp hammering sound may be input. Higher (preferably) than a predetermined level for normal knock control.

Next, FIG. 1 shows a schematic diagram of an engine equipped with a knocking control device to which the present invention is applied. As shown in the figure, this engine is equipped with an air flow meter 2 as an intake air amount sensor provided downstream of an air cleaner (not shown).

The air flow meter 2 is a convention plate (2A, !) which is rotatably provided within the damping chamber.
:, a potentiometer 2B that detects the opening degree of the conventional brake 2A. Therefore,
The intake air current is detected as a voltage output from potentiometer 2B. An intake air flow sensor 4 is provided near the broken air flow meter 2 to detect the temperature of intake air.

A throttle valve 6 is arranged downstream of the air flow meter 2, and a surge tank 8 is arranged downstream of the throttle valve 6.
is straddled. An intake manifold 10 is connected to the surge connector 8, and a fuel injection device 12 is disposed protruding into the intake manifold 10.

The intake manifold 10 is connected to a combustion chamber 14A of the engine body 14, and the combustion chamber 14A of the engine is connected via an exhaust manifold 16 to a catalytic converter (not shown) filled with a three-way catalyst. The engine body 14 is provided with a knocking sensor 18, which is configured with a microphone or the like, and detects whether the engine (7) is knocking. In addition, 20 is a spark plug, 22 is 0 for controlling the air-fuel mixture near the stoichiometric air-fuel ratio,
A sensor 24 is a cold/hot water wetness sensor that detects the engine cooling water temperature, and 58 is an IS switch.

The spark plug 20 of the engine body 14 is connected to a distributor 26, and the distributor 26 is connected to an igniter 28. This distributor 2
6 is provided with a cylinder discrimination sensor 30 and an engine rotation speed sensor 32, which are composed of a pickup and a signal loaf fixed to the distributor shaft.

This cylinder discrimination sensor 30 outputs a generous discrimination signal to the electronic control circuit 34, for example, every 720 degrees of crank angle, and this engine rotation speed sensor 32 electronically controls a crank angle reference position signal, for example, every 30 degrees of crank angle. Output to circuit 34.

The electronic control circuit 34, as shown in FIG.
Access memory (RAM) 36, read only memory (ROM) 38, and central processing unit (CPU) 4
0, the first input/output boat 42, the second input/output boat 44, the first output boat 46, and the second output boat 4
RAM36, ROM38, CP
U40° First input/output boat 42, second input/output boat 44, first output boat 46, and second output boat 4
8 is connected to H-g by the bus 50. An air flow meter 2, a cooling water temperature sensor 24, and an intake temperature sensor 4 are connected to the first input/output boat 42 via buffers 52A, 152B, 52C, a multiplexer 54, and an analog-to-digital (A/D) converter 56. ing. Second entry/exit capo) to 44 &! , a buffer 60 and a comparator 62 to connect the Otsensor 22, and directly
Switch 58 is connected, cylinder discrimination sensor 30 and engine rotation speed sensor 32 are connected via waveform shaping circuit 64, and input circuit 66 and A/D converter 68 are connected.
A knocking sensor 18 is connected via. Further, the first output boat 46 is connected to the igniter 28 via a drive circuit 70, and the second output boat 48 is connected to the fuel injection device 12 via a drive circuit 72.

Here, to further explain the input circuit 66 with reference to FIG. 3, the input circuit 66 includes a filter amplifier 66A connected to the knocking sensor 18, and this filter amplifier 66A includes an integrator 66B and a peak hold circuit. It is connected to the A/D converter 68 via a parallel circuit with 66C. The peak hold circuit 66C is provided with a reset terminal and, for example, a gate (not shown) on the input side, and is reset by a reset signal output from the input/output boat 44 and opened/closed by a gate signal. . Further, a timing signal output from the input/output boat 44 is input to the A/D converter 68.
Starting and stopping of A/D conversion is controlled.

The electronic control circuit 340 ROM 38 stores in advance a basic ignition advance angle map expressed by engine speed and intake air amount, basic fuel injection amount, etc., and a signal from the air flow meter 2 and the engine speed sensor 32. The basic ignition advance angle and basic fuel injection amount are read out by the signal, and various signals including those from the cooling water temperature sensor 24 and the intake air temperature sensor 4 read out the basic ignition advance angle and basic fuel injection amount. A corrected ignition advance angle and a corrected fuel injection amount are added to control the igniter 28 and the fuel injection system 2. The air-fuel ratio signal output from the sensor 22 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.

Furthermore, when the level of the electrical signal output from the knocking sensor 18 exceeds a predetermined level,
It is determined that knocking has occurred, and the igniter 28 is controlled so that the ignition timing is delayed. When this reverse Vζ and the level of the electrical signal output from the knocking sensor 18 are below a preset level, it is determined that knocking is not occurring, and the ignition timing is controlled to the maximum advance angle that does not cause knocking. be done.

Next, a detailed explanation will be given of the present invention for detecting whether or not a knocking sensor or the like used in the engine as described above is abnormal. A first embodiment of the present invention is shown in FIGS. 4 to 6. In this embodiment, the gate is opened for a period of 30° CA from top dead center (TIC) to before top dead center (BTDC), and a pseudo knocking signal is input to detect an abnormality in the knocking sensor, etc. It is something. FIG. 4 shows the interrupt process interrupted by TDC, FIG. 5 shows the interrupt process interrupted by BTDC600CA, and FIG. 6 shows the interrupt process interrupted by BTDC30°CA. Note that the pseudo knocking signal is supplied to the knocking sensor by hitting the engine body with a hammer.

First, when the engine piston reaches TDC due to a crank angle reference signal or the like, the interrupt process shown in FIG. 4 is performed, and in step 40, the gate is opened and the process returns to the main routine. As a result, the operation of the peak hold circuit 66C is completed, and the filter amplifier 66
The peak value of the pseudo knocking signal that has passed through A is held. Next, when the crank angle reaches BTDC600, the interrupt process shown in FIG. 5 is performed, and in step 5o it is determined whether or not the abnormality detection mode is in effect, that is, whether or not the Is switch 58 is on. If it is determined in step 50 that the mode is abnormality detection mode, the process returns to the main routine.

On the other hand, if it is determined in step 50 that the mode is not abnormality detection mode, the gate is closed in step 52, the A/D converter 68 is activated, and the peak hold signal outputted from the peak hold circuit 66C is A/D
Start the exchange and return to the main routine. In the main routine, the A/D converted peak value is compared with a predetermined level obtained by multiplying the average level obtained by the integrator 66B and A/D converted by the A/D converter 68 by a constant K. and performs normal knocking control. Subsequently, when the crank angle reaches 30° BTDC, the interrupt process shown in FIG. 6 is performed, and in step 6°, it is determined whether or not the abnormality detection mode is in effect, that is, whether or not the Is switch is on. If it is determined in step 60 that the mode is not abnormality detection mode, the process returns to the main routine.

On the other hand, if it is determined in step 6o that the mode is abnormality detection mode, the gate is closed in step 62, and A/D conversion of the peak bold signal is started.
Return to main routine.

The main routine compares the peak value with a predetermined level,
Performs knocking control. Then, while knocking control is being performed based on the pseudo-knocking signal, a timing light is used to detect whether or not the ignition timing is delayed. Here, if the ignition timing is delayed, it means that knocking control is being performed, that is, the knocking sensor is normal. Conversely, if the ignition timing is not delayed, it means that knocking control is not being performed even though knocking is occurring, that is, the knocking sensor is abnormal.

FIG. 7 shows the signal timing of each part in the above embodiment. In Fig. 7, (a) kl crank angle, (b) pseudo knocking signal, (C) gate signal when performing normal knocking control, (d) gate signal in abnormality detection mode, and (e) k'f indicates the peak hold signal.

8 to 10 show flowcharts of the operation of the second embodiment of the present invention. In this embodiment, when an abnormality is detected, the gate is kept open at all times and a pseudo knocking signal is input. Note that FIGS. 8 and 9 of this embodiment are the same as FIGS. 4 and 5 of the first embodiment, so the same parts are denoted by the same reference numerals and the explanation thereof will be omitted.

When the crank angle reaches 30 degrees BTDC, the interrupt process shown in FIG. 10 is performed, and in step 80 it is determined whether or not the abnormality detection mode is in place. If the aN detection mode is 1, the process returns to the main routine. . On the other hand, if it is determined in step 80 that the mode is abnormality detection mode, in step 82, the A/
Df conversion is activated and A/D conversion of the peak hold signal is started. Then, in step 84, a reset signal is input to the reset terminal of the peak hold circuit to reset the peak bold value before starting A/D conversion, and then the process returns to the main routine.

FIG. 11 shows the timing of signals of each part in the above embodiment. In FIG. 11, (,) shows the crank angle, (b) shows the pseudo knocking signal, (C) shows the 7-bit signal, and (d) shows the peak hold signal.

According to the present invention, as explained above, the gate.

A unique effect can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an engine to which the present invention is applied;
FIG. 2 is a block diagram showing the electronic control circuit in FIG. 1, FIG. 3 is a block diagram showing details of the knocking detection device, and FIGS. 4 to 6 show the first embodiment of the present invention. The flowchart, FIG. 7 is a diagram showing the timing of signals of each part in the above embodiment, and FIGS.
FIG. 11, a flowchart showing the embodiment, is a diagram showing the timing of signals of each part in the above embodiment. 18...Knocking sensor, 32...Distributor, 34...Electronic control circuit, 5B...IS switch. Agent Tatsuyuki Unuma (and 2 others) Figure 3 Figure 6L (1 Figure 7 Figure 7 ¥81 1 Figure 9 10 2] D 11th 1 (0) Knee Lnee Lnee Keyaki Kyo - (d ) - Higo - Tsubotyo DC ^ to ~ ~ V

Claims (1)

[Claims] (1) Equipped with a knocking sensor that detects engine knocking and outputs an electrical signal, opens a gate for a predetermined period of time at every predetermined crank angle to input the electrical signal, and when the level of the input electrical signal exceeds a predetermined level. In order to detect an abnormality in the knocking control device that controls the ignition timing to be delayed when the engine is idle, the gate is opened for a period exceeding the predetermined time period when the engine is idle, and the electric signal is inputted. When the level of the engine exceeds a predetermined level, knocking control is performed to delay the ignition timing, and a knocking signal similar to the knocking sensor 4 is supplied when the engine is idle, and it is detected whether or not the ignition timing is delayed. A method for detecting abnormalities in knocking control devices.