JPS58138264A - Detecting method of abnormality in knocking controller - Google Patents

Abstract

PURPOSE:To easily detect abnormality in the method of detecting the abnormality in a knocking controller, by supplying a false signal of knocking to a knocking sensor to detect whether ignition timing is delayed or not. CONSTITUTION:At idling time of an engine, a false signal of knocking is supplied to a knocking sensor to detect whether ignition timing is delayed or not. To perform such knocking control at idling time of the engine, the control is operated by deciding whether, for instance, an idle speed switch (IS switch) is turned on or not. Further a timing light or the like is used as an ignition timing detector. In this way, abnormality can be easily detected.

Description

Detailed Description of the Invention The present invention relates to a method for detecting an abnormality in a knocking control device, and particularly relates to a knocking control device that provides a knocking sensor for each cylinder group of an engine and performs knocking control for each cylinder when knocking occurs. The present invention relates to a method for detecting anomalies in.

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 kind of knocking causes unpleasant noises, and when severe knocking occurs, strong air column movement occurs within the cylinder, resulting in localized abnormal high temperatures within the cylinder, which can damage the engine. become. However, the knocking phenomenon itself does not have a negative effect on the engine, and even if knocking occurs by advancing the ignition timing, the fuel efficiency of the vehicle can be improved by increasing the combustion efficiency of the engine. From the viewpoint of improving fuel efficiency, allowing a moderate amount of knocking is suitable for rounding up the engine to obtain an operating state with an R overdrive rate. Therefore, knocking control is carried out in accordance with various conditions in order to optimize the operating efficiency of the engine and keep the knocking sound level below a predetermined level.

Conventionally, in performing such knocking control, multiple cylinders of an engine are divided into multiple cylinder groups, and each of these cylinder groups is equipped with a knocking sensor consisting of a microphone, etc. that detects knocking sound and outputs an electrical signal. is provided, and when the level of the electric signal exceeds a predetermined level in a high load region, the ignition timing of the cylinder corresponding to the knocking sensor exceeding the predetermined level is delayed, and when the level of the electric signal is below the predetermined level, the ignition timing is set to the predetermined level. Control is performed for each cylinder so that the ignition timing of the cylinder corresponding to the following knocking sensor is advanced to an angle that does not cause knocking. For example, in the case of a six-cylinder engine, the knocking sensors include a first knocking sensor that detects knocking in the first to third cylinders, and a knocking sensor that detects knocking in the fourth to sixth cylinders.
A second knocking sensor that detects cylinder knocking is attached to the engine body.

Note that in the light load range, knocking control is unnecessary, so ignition timing is not controlled.

However, the knocking sensors that detect knocking
If an abnormality such as wire breakage, sensor deterioration, or poor contact occurs, a knocking state cannot be detected, and an electrical signal of a predetermined level or higher will not be output even though the engine is knocking. In particular, if it is determined that there is no knocking even though the engine is knocking, the ignition timing will advance to a "moth avenue" state, causing the engine to violently knock or erect, and in the worst case scenario. Problems arise in that the spark plug and piston are melted and damaged, the gasket blows out, and the engine is destroyed.

The present invention has been made to solve the above-mentioned problems, and in particular, it is an object of the present invention to provide a method for detecting an abnormality in a knock control device, which can easily detect an abnormality in a knock sensor.

To achieve the above object, the present invention has a configuration in which a knocking sensor that detects engine knocking and outputs a signal No. 16 is provided for each cylinder group of the engine, and each cylinder is detected based on the electrical signal. In detecting an abnormality in a knocking control device that controls ignition timing, knocking control is performed for the specific cylinder to delay the ignition timing when the specific cylinder of the engine is turned on, and a pseudo-knocking signal is sent to the knocking sensor when the engine is idle. This is useful for detecting whether or not the ignition timing is delayed. In order to perform such knocking control when the engine is idling, for example, an idle speed switch (Is switch) for short circuiting is used to stop calculating the ignition timing and fix it at a desired set angle during idling.
This is done by determining whether the switch is turned on or not. Further, the pseudo knocking signal is supplied to the knocking sensor by, for example, hitting the engine body with a hammer. As a result, an abnormal or normal state of the knocking sensor appears as a change in the ignition timing of a specific cylinder, so by detecting the ignition timing of a specific cylinder, it is possible to detect whether the cedar knocking sensor is normal or abnormal. . Note that a timing light or the like that blinks depending on the crank angle is used as the ignition timing detection device.

Here, from the viewpoint of easily detecting an abnormality in the knocking sensor, a pseudo-knocking signal is supplied to the knocking sensor when the engine is idling, and knocking control is performed to determine the ignition timing using an ignition timing detection device such as a timing light. Although it is possible to detect the ignition timing of each cylinder by determining the cylinder to be controlled for each knocking sensor, the ignition timing detection device may be used to detect the ignition timing of each cylinder.

Problems arise in that the connection must be changed to detect the timing, and a timing mark must be placed at the top dead center of each cylinder.

According to the above configuration of the present invention, an effect of %N can be obtained in that the connection change of the ignition timing detection device and the addition of a timing mark, which are applied to the above-described modified product, are not lost.

Next, FIG. 1 shows an example 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 rotatably installed in the damping chamber.
It consists of a potentiometer that detects 11 degrees t, and 2B. Therefore, the amount of intake air is determined by potentiometer 2.
It is detected as the voltage output from B. 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, and a surge tank 8 is arranged downstream of the throttle valve 6.
is provided. An intake manifold 10 is connected to the surge tank 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 first knocking sensor 18 and a second knocking sensor 19, which are configured with a microphone or the like and detect engine knocking. The sensor 24 for controlling the air to near the stoichiometric air-fuel ratio is a cold/hot water temperature sensor that detects the engine cooling water temperature.

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 3o and an engine rotation speed sensor 32, each of which includes a pickup and a signal rotor fixed to a distributor shaft.

This cylinder discrimination sensor 30 outputs a cylinder discrimination signal to the electronic control circuit 34 to which the Is switch 58 is connected, for example, every 720 degrees of crank angle, and the engine rotation speed sensor 32
outputs a crank angle reference position signal to the electronic control circuit 34, for example, every 30 degrees of crank angle.

The electronic control circuit 34, as shown in FIG.
It is configured to include an access memory (RAM) 36, two output ports 44, a first output port 46, and a second output port 48.
The CPU 40, the first input/output boat 42, the second input/output port 44, the first output port 46, and the second output port 48 are connected by a bus 50. The first input/output boat 42 includes buffers 52A, 52B, 52C1
Multiplexer 54, analog-digital (A/D)
The air flow meter 2 , the cooling water temperature sensor 24 , and the intake air temperature sensor 4 are connected via the converter 56 . The multiplexer 54 and A/D converter 56 are controlled by signals output from the first input/output port. The second input/output boat 44 is connected to the O sensor 22 via a buffer 60 and a comparator 62, directly connected to the Is switch 58, and connected to the cylinder discrimination sensor 30 and the engine speed via a waveform shaping circuit 64. sensor 32
are connected to the knocking sensors 18 and 19 via an input circuit 66 and an A/D converter 68. The input circuit 66 and A/D converter 68 are controlled by signals output from the second input/output boat 44, and take in electrical signals output from one of the knocking sensors at predetermined time intervals. (9) The first output port 46 is connected to the igniter 28 via a drive circuit 70, and the second output port 48 is connected to the fuel injection device 12 via a drive circuit 72.

The ROMa 8 of the electronic control circuit 34 stores in advance a basic ignition advance angle map expressed by engine speed and intake air amount, basic fuel injection amount, etc.
The basic ignition advance angle and the basic fuel injection amount are continuously outputted by the signals from the meter 2 and the engine speed sensor beak 32, and by various signals including the signals from the cooling water sensor 24 and the intake temperature sensor 4. , a corrected ignition advance angle and a corrected fuel injection amount are added to the basic ignition advance angle and basic fuel injection amount, and the igniter 28 and the fuel injection device 12 are controlled. 0! 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 a normal air-fuel ratio.

Further, when the level of the electric signal output from the knocking sensor 18, 19 exceeds a predetermined level, it is determined that knocking has occurred, and the igniter 28 is controlled to delay the ignition timing. Conversely, when the level of the electrical signal output from the knocking sensor 18, 19 is below a preset level, it is determined that no knocking occurs, 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 the knocking sensor used in the engine as described above is abnormal. Third @ is a flowchart of an interrupt routine performed every time the top dead center occurs when an embodiment of the present invention is implemented by an electronic control circuit.

First, in step 81, based on the signals from the air flow meter 2 and the engine speed sensor 32, it is determined whether the vehicle is in a high load region or a low load region, that is, in a region where knocking control is required. If it is determined in step 81 that the knocking control is required, then in step 82 it is determined which cylinder the knocking control is for, based on the signal output from the cylinder discrimination sensor. Then, in step 83, it is determined whether the electrical signal output from the knocking sensor exceeds a preset predetermined level, that is, whether or not knocking has occurred, and if knocking has occurred, In step 84, knocking control is performed to retard the ignition timing by 01L crank angle. Further, if it is determined that knocking is not occurring, the ignition timing is advanced to a dovetail advance angle that does not cause knocking.

If it is determined in step 81 that the area is not in the JliL area where knocking control is required, in step 85
It is determined whether the switch 58 is on. If the Is switch is not on, the interrupt routine shown in Figure 3 is terminated, and if the I8 switch is on,
In step 86, it is determined whether pseudo-knocking has occurred, that is, whether a pseudo-knocking signal is supplied to the knocking sensor and an electrical signal corresponding to the pseudo-knocking signal is input to the electronic control circuit. Similar to step 83, this determination is made based on whether the level of the electrical signal exceeds a predetermined level. If there is no pseudo-knocking, this interrupt routine tg is completed, and if there is pseudo-knocking, in step 87, the ignition timing of only a specific cylinder (for example, the first cylinder) is delayed by # degrees in terms of crank angle. Then, using an ignition timing detection device such as a timing light, it is detected whether or not the ignition timing is actually delayed. Here, if the ignition timing is delayed, the knocking sensor is normal, and if the ignition timing is not delayed, knocking occurs.If the knocking control is not performed despite the ignition timing, it is To9, and the knocking sensor is abnormal. means. Therefore, it is possible to detect whether or not the knock sensor is abnormal.

In this embodiment, the crank angle in step 87 is made larger than the crank angle in step 84, and the crank angle in step 87 is held longer than the crank angle in step 84. It is preferable to make it longer than the holding time.

Furthermore, if the amount of retardation of the ignition timing or the retardation holding time is made different for each knocking sensor in step 87, it is possible to detect which of the eight knocking sensors is abnormal.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an engine kyr< to which the present invention is applied; FIG. 2 is a block diagram showing a single child control circuit in FIG. 1; 18.19 Knocking sensor, 32 Distributor, 34 Electronic control circuit.

Claims (1)

[Claims] (1) A knocking sensor that detects engine knocking and outputs an electrical signal is provided for each group of the engine, and detects abnormalities in the knocking control device that controls ignition timing for each cylinder based on the electrical signal. Specifically, when the engine exceeds a specific temperature, knocking control is performed on the specific cylinder to delay the ignition timing, and a pseudo knocking signal is supplied to the knocking sensor during the engine idle time to determine whether or not the ignition timing is delayed. A method for detecting an abnormality in a knocking control device in which the detection is performed as a characteristic.