JPS58118923A - Knocking detector - Google Patents

Abstract

PURPOSE:To detect knocking surely for a wide range of number of revolutions by controlling the gain of an amplifier circuit which amplifies the detection signal for engine oscillations by a pickup according to the number of revolutions of the engine. CONSTITUTION:The gain of an amplifier circuit 12 which amplifies the detection signal for engine oscillations from a pickup is controlled with a detecting part 17 for the number of revolutions controlled a t required timings, a multiplexer 16, a gain control circuit 15, etc. Then, the detection signal for oscillations of the engine differing in frequency over a wide range of the number of revolutions at easy to process levels is applied to a knocking deciding part 13, by which the knocking is detected accurately for a wide range of number of revolutions.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a knocking detection device for detecting knocking in an engine of an automobile, etc., and an object of the present invention is to accurately detect knocking over a wide range of rotational speeds.

Engine knocking in automobiles and the like is one of the factors that increases fuel consumption and impairs vehicle safety. Such knocking can be detected by observing engine vibrations.

Therefore, knocking can be detected by detecting engine vibration by vibration piston pickup and processing the output signal of the vibration piston.

By the way, FIG. 1 shows an example of the vibration level of the output signal of the vibration pickup. FIG. 1 shows the average vibration level and range of vibration levels of knocking vibration when knocking occurs. From FIG. 1, the dynamic range of the vibration level is about 50 dB. As shown in FIG. 1, the level of the vibration pink-up output signal varies greatly depending on the rotational speed. FIG. 2 shows an example of a conventional knocking detection device. In Fig. 2, 1 is the input end of the vibration pickup signal, 2 is the amplifier circuit, 3 is the )/soaking determination section, 4 is the output end of the knocking detection pulse, 6 is the input end of the ignition timing signal, and 6 is the waveform shaping section. , 7 is a timing generator.

The vibration pickup signal applied to input end 1 is approximately 50d
B changes, so if the amplification degree of the amplifier circuit 2 is constant, the level of the vibration pickup signal is small during low speed rotation, making it difficult for the knocking judgment section 3 to determine knocking, and the level of the vibration pickup signal during high speed rotation is small. Since this is large, the output signal of the amplifier circuit 2 may become saturated, making it impossible to make an accurate knocking determination. Further, since the battery voltage of a general automobile varies over a range of 8 to 16 V, it is difficult to make the output level of the amplifier circuit 2 appropriate over a wide range of rotational speeds.

As described above, conventional devices have the drawback of not being able to cope with a wide dynamic range of vibration pickup signal levels.

The present invention aims to maintain a signal level that is easy to process over a wide range of rotation speeds by controlling the amplification degree of the amplifier circuit according to the rotation speed, and to accurately detect knocking from low to high speed rotations. It is.

An embodiment of the present invention will be described with reference to FIGS. 3 and 4. 11 is an input terminal for a vibration pickup signal, 12 is an amplifier circuit, 13 is a knocking determination section, 14 is an output terminal for a knocking detection pulse, 15 is a gain control circuit, 16 is a multiplexer, 17 is a rotation speed detection section, and 18 is an ignition timing The input terminal, 19 is a waveform shaping section, and 2o is a timing generation section.

The vibration picker knob signal applied to the input end 11 is amplified by the amplifier circuit 12 and processed by the non-king determining section 13 to determine whether there is excessive knocking. The ignition timing signal 18 is shaped by a waveform shaping section 19 and then enters the timing generating section 2o. The rotation speed detection section 17 detects the rotation speed, and the multiplexer 16 sends an output corresponding to the rotation speed to the gain control circuit 15 to control the degree of amplification.

An example of the gain control circuit 15 is shown in FIG. The gain control circuit 16 consists of n resistors and analog switches, and by closing only one analog switch according to the signal from the multiplexer 16 according to the rotation speed, the feedback resistance of the amplifier circuit 12 is determined, and the amplification degree is determined. It is decided. That is, an appropriate amplification degree is determined by providing a necessary number of resistors and switches in advance and selecting them using the multiplexer 16 according to the rotational speed. In this way, the amplifier circuit 12 amplifies the vibration pickup signal from low speed rotation to high speed rotation to a signal level that is easy for the knock/socking determination section 13 to process, so knocking can be determined over a wide range of rotation speeds. becomes.

The present invention has the above configuration, and according to the present invention, since the gain of the amplifier circuit is controlled according to the rotation speed, it has the advantage that accurate knocking detection can be performed over a wide range of rotation speeds. It is.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between engine speed and vibration level due to vibration pickup, Fig. 2 is a diagram of a conventional knocking detection device, and Fig. 3 is a diagram of a non-knocking detection device according to an embodiment of the present invention. Block Diagram FIG. 4 is a block diagram of the main parts of the device. 11...Input end, 12...Amplification circuit,
13...Knocking determination section, 14...
Output terminal, 15...Gain control circuit, 16...
...Multiplexer, 17...Rotation speed detection section,
18...Ignition timing signal input terminal, 19.
... Waveform shaping section, 2゜ ... Timing generation section. Name of agent: Patent attorney Toshio Nakao and 1 other person11
Figure Crep) @Number 2 Figure 13 Figure 4

Claims (1)

[Claims] (1) A vibration pickup that detects engine vibration, an amplification circuit that amplifies the output signal of the vibration pickup, a knocking determination section that determines knocking based on the output of the amplification circuit, and a knocking determination section that determines knocking based on the output of the amplification circuit; A knocking detection device equipped with a gain control circuit that controls the gain of the circuit. (2. In the knocking detection device according to claim 1, a gain control circuit is configured by connecting a plurality of series circuits of a resistor and an analog switch in parallel, and the plurality of analog switches are A knocking detection device characterized in that one of the switches is closed.