JPH0323752B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for an internal combustion engine of the type that corrects the ignition timing of the engine using a knocking indication signal outputted by a knocking sensor in an internal combustion engine, and particularly to a device for controlling the ignition timing of an internal combustion engine. This invention relates to a device with improved control when a condition occurs.

The signal generation period is synchronized with the rotation of the internal combustion engine, the ignition system has an ignition timing control function, and the vibration of the engine.
and an arithmetic circuit that detects knocking factors such as noise by a knocking sensor and calculates a correction amount for correcting the basic ignition timing instructed by the signal generator, and the ignition device ignites the ignition at the corrected ignition timing. According to a conventional ignition timing control device of the type that performs the following, the correction amount is calculated and output for each knocking display signal (referred to as a knocking signal) output from a knocking sensor, and the ignition timing is delayed by a predetermined amount. When the knocking signal interval becomes longer than a predetermined time (the knocking interval becomes longer than a certain amount or the knocking state disappears), the ignition timing is advanced by a predetermined amount at fixed intervals, and abnormalities such as wire breaks, short circuits, and breakdowns are detected. When a condition occurs, that is, when the knock signal becomes a fail condition, the ignition timing is controlled to be maximum retarded after a predetermined period of time. Therefore, there is no problem when the knock signal generation is detected normally, but even if the knock signal temporarily fails due to a momentary disconnection of the knock signal, the ignition timing will be controlled to the maximum retard. However, the disadvantage was that the torque of the internal combustion engine was unnecessarily reduced.

In order to eliminate this drawback, the present invention provides an ignition timing control device that is configured to retard the ignition timing to the maximum after a predetermined period when a failure condition occurs. Thereby, even if the knock signal temporarily fails, the torque of the internal combustion engine can be prevented from decreasing unnecessarily. The present invention will be explained below with reference to the drawings.

In FIG. 1 showing a block diagram of an embodiment of the present invention, 1 indicates a knocking sensor that detects knocking factors occurring in the engine cylinder through vibration, pressure, etc. and converts it into an electrical signal, and 100 indicates a basic ignition timing. 2 is an arithmetic circuit that calculates the correction amount from the sensor signal 21 obtained by the knocking sensor 1,
A frequency filter 3 that passes only frequency components containing a knocking component determines whether or not there is a knocking component in the output signal of the frequency filter 2, and generates a knock signal (used as a retard timing signal) in response to the knocking component. A knocking determination circuit 5 is connected to a frequency filter to determine whether the signal from the knocking sensor 1 is in an abnormal state such as a disconnection or short circuit, that is, in a fail state, and outputs a fail response signal. The fail determination circuit 7 includes a first timer, which is reset when the knocking determination circuit 3 determines that there is knocking, and serves as an advance timing signal generating means for outputting an advance timing signal at first predetermined time intervals.
Reference numeral 6 denotes a fail determination circuit 5, and when the fail determination circuit 5 determines that the failure has occurred, a second timer serving as fail detection signal output means outputs a fail detection signal after a second predetermined time period that is longer than the first predetermined time period. A gate circuit that transmits or not transmits an input signal to the output side according to a control signal from
is a retard timing signal, an advance timing signal,
An up-down counter calculates the ignition timing correction amount based on the fail detection signal, and 10 represents a D/A conversion circuit that converts the digital output signal 9 into an analog ignition timing correction amount. 11 is
A basic ignition timing display signal 31 outputted from a signal generator 12 synchronized with the engine is transmitted to a D/A conversion circuit 10.
This is an ignition device that determines the ignition timing by correcting it according to the output signal of the ignition system.

The operation will be explained with reference to FIG. 2 which shows a timing chart of the signal waveform of the main part of the configuration in FIG. The components are separated from noise and become the filter output signal 22. The filter output signal 22 is sent to a knocking detection circuit 3, which detects the presence or absence of a knocking component as a knock signal (retard timing signal) 23.
The ignition timing correction amount calculation circuit 9 calculates to retard the ignition timing. On the other hand, the first timer 7 counts the advance timing from the time when the knock signal 23 is generated, and when the knock signal interval is longer than a predetermined time, outputs the advance timing signal 26, passes through the gate 8, and starts the ignition. It is input 27 to the timing correction amount calculating circuit 9 and is calculated to advance the angle (see section A in Figure 2).Here, if the signal from the knocking sensor 1 is in a fail state, the signal from the knock sensor 1 is in a fail state or the knock sensor is in a fail state. When an abnormality is detected, the timing is not immediately retarded, but is delayed for a second predetermined time, which is longer than the first predetermined time, to reach the maximum retardation. If the engine returns to normal immediately after the engine failure, if a knock signal continues to occur, retard angle control is continued, and if neither knock signal nor fail response signal 25 is detected, advance angle control is performed to maintain the engine state. This is to perform appropriate control.

In this embodiment, a gate 8 is provided between the first timer 7 and the arithmetic circuit 9, and when the fail determination circuit 5 determines that the failure has occurred, the fail response signal 25 is output.
The gate 8 is immediately closed to prevent the advance timing signal 26 from being applied to the ignition timing correction amount calculation circuit 9, thereby prohibiting the advance angle calculation of the circuit. Note that if the fail state is instantaneous or temporary and is no longer a fail state and returns to a normal state, the fail response signal also returns and the gate circuit 8 is also opened to allow the advance timing signal 26 to pass.

When the gate 8 is closed and the advance timing signal is blocked, the fail detection signal 28 generated by the second timer 6 after a predetermined time is input to the ignition timing correction amount calculation circuit 9, and the maximum retardation amount is calculated. It is controlled so that (Refer to the solid line of signal 30 in Figure 2)
Therefore, in this embodiment, the sensor signal 21
Advance control is not performed from the time when the engine fails until the ignition timing correction amount reaches its maximum retard, so even if knocking occurs in the engine during this period, damage to the engine can be reduced. .

As described above, in the present invention, the ignition timing correction amount is not controlled in the direction of maximum retardation until a predetermined period has elapsed from the time when the sensor signal 21 becomes in a fail state. This has the effect of preventing the torque of the internal combustion engine from decreasing unnecessarily even if the engine temporarily fails.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 shows a timing chart of the main signal waveforms of FIG. 1. 1: Notking sensor, 2: Frequency filter,
3: knocking determination circuit, 5: fail determination circuit, 6: second timer, 7: first timer, 8: gate, 9: ignition timing correction amount calculation circuit, 31: ignition device, 100: calculation circuit.

Claims (1)

[Scope of Claims] 1. An ignition timing control device that corrects the ignition timing of an ignition device of an internal combustion engine based on a knocking sensor output signal, which determines the presence or absence of knocking based on the knocking sensor output signal, and when knocking is present. knocking determination means for outputting a knock signal; fail determination means for detecting whether or not the knocking sensor output signal is in a fail state and outputting a fail response signal; A lead angle timing signal generation means for outputting an advance timing signal; a fail detection signal output means for outputting a fail detection signal after a second predetermined period longer than the first predetermined period after receiving the fail response signal; When the angular timing signal is input, the ignition timing correction amount is changed in the advance direction, when the fail detection signal is input, the ignition timing correction amount is changed in the maximum retard direction, and when the knock signal is input, the ignition timing correction amount is changed in the maximum retard direction. a calculation means for changing an ignition timing correction amount in a retard direction; and receiving a fail response signal from the fail determination means, and inputting the advance timing signal to the calculation means while the fail response signal is being outputted. An ignition timing control device for an internal combustion engine, comprising a gate means for inhibiting the ignition timing.