JPS6352690B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a detection circuit for knocking occurring in an internal combustion engine, and specifically to a circuit for detecting a cylinder in which knocking occurs and a knocking level in a multi-cylinder engine.

[Prior Art] Conventionally, knocking detection devices for internal combustion engines have been disclosed in Japanese Patent Application Laid-open No. 55-93028 and Japanese Patent Application Laid-Open No.
The invention disclosed in Publication No. 53-14208 has been proposed, but the former appropriately detects how often knocking occurs with respect to the number of engine ignitions, and the latter detects only the knocking waveform from the knocking vibration. In order to separate and extract noise, the method for separating noise is recognized as being ingenious.

[Problems to be solved by the invention] However, now that the timing of knocking occurrence and the frequency of knocking occurrence are known,
Improving the accuracy in measuring the knocking frequency as in the former case, or extracting the knocking waveform as in the latter case, is not necessarily effective for maintenance purposes, and it is not possible to easily detect the cylinder in which knocking occurs or the knocking level. There is a problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a knocking detection circuit that determines the presence or absence of knocking in each cylinder with a simple operation in a multi-cylinder engine, and determines the knocking level of the cylinder in which knocking occurs.

[Means for Solving the Problems] The present invention provides a knock sensor that detects knocking in a multi-cylinder engine and outputs a knocking signal, and a knock sensor that generates a pulse when the knocking signal output from the knock sensor is larger than a predetermined output. a comparator that outputs a signal; a pick-up that is movably installed to detect the discharge current of each spark plug of the multi-cylinder engine and generates an output signal in accordance with the discharge current of the spark plug; a monostable multivibrator that generates a pulse signal based on the output signal of the comparator, an AND circuit that generates a pulse signal when the respective pulse signals of the comparator and the monostable match vibrator are generated together, and from the AND circuit. and a display means for displaying a perceptible display based on the outputted pulse signal.

[Operation] In the present invention, when knocking occurs in a multi-cylinder engine, it is detected by the knock sensor, the knock sensor outputs a knocking signal, and the comparator responds to the knocking signal when the outputted knocking signal is larger than a predetermined output. Outputs a pulse signal.

On the other hand, the discharge current of each spark plug of a multi-cylinder engine is detected by a pick-up, and since the pick-up is installed so that its mounting position can be changed, the discharge current of each spark plug of a multi-cylinder engine is detected. An output signal is generated based on the output signal of the pickup, and a monostable multivibrator generates a pulse signal according to the output signal of the pickup.

When knocking occurs in a multi-cylinder engine, a pick-up is attached to each spark plug in turn, and when each pulse signal of the comparator and monostable multivibrator is generated together, a pulse signal is output from the AND circuit, and this output is Based on this, the display means performs a perceivable display.

[Effects of the Invention] In the present invention, the display means displays an indication only when knocking occurs in the cylinder of the spark plug to which the pickup is attached. Therefore, by changing the cylinder to which the pickup is attached while checking the display on the display means, it is possible to determine which cylinder is causing knocking. In addition, since the comparator generates a pulse signal only when the knocking signal output from the knock sensor exceeds a predetermined output, if knocking is not displayed on the display means even if knocking occurs, the set predetermined output It can be determined that the knotting is smaller.

[Example] Next, the present invention will be explained based on FIG. E is 4
A cylinder gasoline engine, V is a battery, C is an ignition coil, B is an interrupter, D is a distributor, and P1 to P4 are spark plugs installed in each cylinder. The knock sensor 1 is a piezoelectric or magnetostrictive vibration detector mounted on the cylinder block by a known method to measure engine vibration. In this embodiment, when knocking occurs, the engine vibrates as shown in FIG. 2A. Convert to voltage waveform. A knock sensor 1 is installed near a cylinder of a four-cylinder gasoline engine E to detect knocking. The filter 2 limits the input frequency of the knocking signal output from the knock sensor 1 to the comparator 3 to prevent malfunctions due to noise or the like. Comparator 3
As shown in FIG. 3, the reference voltage set by the voltage dividing circuit of the power supply voltage made up of the voltage dividing resistor 13 and the voltage dividing resistor 14 is compared with the output of the knock sensor 1 inputted through the filter 2. , when the output of the knock sensor 1 is large, a knocking pulse shown in FIG. 2B is output.

The pick-up 4 is installed so that its mounting position can be changed in order to detect the spark signals shown in Fig. 2C from each of the spark plugs _P1 to _P4 installed in the four-cylinder gasoline engine E, and detects knocking. In some cases, the cylinder in which knocking occurs can be determined by determining in which cylinder ignition occurs.
Monostable match vibrator 5 is pick up 4
The pulse signal shown in FIG. 2D is generated as a spark discharge pulse from the spark signal detected in FIG. Here, the pulse width t ₂ of the spark discharge pulse needs to be set smaller than the spark discharge time t ₁ between the cylinders, and if t ₂ becomes larger than t ₁ , noise will be input and the cylinder in which knocking will occur cannot be accurately identified. It becomes impossible to distinguish.

The AND circuit 6 inputs the knocking pulse and the spark discharge pulse respectively output from the comparator 3 and the monostable match vibrator 5, and when knocking occurs in the cylinder in which the spark signal is detected, as shown in FIG. 2E. Outputs a pulse signal. this is,
This is because in the four-cylinder gasoline engine E, when knocking occurs in any cylinder, the cylinder in which the knocking occurs can be determined by knowing which spark plug caused the spark. Therefore, if the AND circuit 6 outputs a pulse signal when the mounting position of the pickup 4 is changed, it can be determined that knocking has occurred in the spark plug to which the pickup 4 is attached.

The monostable multivibrator 7 is an AND circuit 6
Figure 2 shows the pulse width of the pulse signal output from F.
As shown in FIG. 2, the output of the monostable multivibrator 7 is amplified to a level that can be detected by humans, and the lamp 9 is blinked via the inverter 8.

The knocking can be displayed by storing the output of the AND circuit 6 in the memory 10 and continuously lighting the lamp 9, but in this case, a reset switch 10A is installed. Further, a buzzer may be used as the display device.

The knocking level to be detected can be easily adjusted by adjusting the reference voltage of the comparator 3 using a variable resistor 13A as shown in FIG.

In FIGS. 3 and 4, the terminal 11 inputs the signal from the filter 2, the terminal 12 is the output to the AND circuit 6, and the terminal 15 is connected to the power supply circuit.

As described above, according to the present invention, it is easy to identify the cylinder in which knocking occurs, and the knocking level can also be easily determined.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the knocking detection device of the present invention, Figs. 2 A to F are waveform diagrams for explaining its operation, and Figs. 3 and 4 are partial circuit diagrams showing the voltage dividing circuit of the comparator. be. In the figure, 1...knock sensor, 3...comparator, 4...pickup, 5...monostable multivibrator, 6
...AND circuit, 9...lamp.

Claims (1)

[Scope of Claims] 1. A knock sensor that detects knocking in a multi-cylinder engine and outputs a knocking signal; and a comparator that outputs a pulse signal when the knocking signal output from the knock sensor is larger than a predetermined output. , a pick-up whose mounting position can be changed to detect the discharge current of each spark plug of the multi-cylinder engine, and which generates an output signal in accordance with the discharge current of the spark plug; and a pick-up which generates a pulse based on the output signal of the pick-up. a monostable multivibrator that generates a signal; an AND circuit that generates a pulse signal when the respective pulse signals of the comparator and the monostable multivibrator are both generated; and an AND circuit that generates a pulse signal based on the pulse signal output from the AND circuit. a knocking detection circuit for an internal combustion engine, comprising a display means for detectably displaying a knocking detection circuit for an internal combustion engine.