JPS6239308Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a knocking detection device to be applied to an ignition timing control device for an internal combustion engine that detects knocking that occurs in an internal combustion engine and optimally controls the ignition timing, particularly in a multi-cylinder internal combustion engine. The present invention relates to a knocking detection device that detects knocking from pressure pulsations in cooling water caused by knocking that occurs in each cylinder.

The knocking detector, which detects knocking from the pressure pulsations of the cooling water, is mounted on the cylinder block so that the vibrating body of the detector is exposed to the cooling water in the water jacket 6 of the internal combustion engine 1, as shown by reference numeral 2 in FIG. The knocking detector 2 is installed by screwing, and as shown in the block diagram of the knock feedback ignition system shown in FIG. 1, an output signal corresponding to knocking from the knocking detector 2 is input to a knocking detection circuit 3. The ignition timing control device 4 advances or retards the ignition timing in accordance with the output of the detection circuit 3 to control it to the optimum position, and the output signal of the ignition timing control device 4 is connected to the engine 1 via the ignition device 5. The mixture is ignited by the spark plug.

By the way, the water-cooled cooling system for an internal combustion engine is as shown in FIG.
0 with a hose, and water pump 11
The cooling water is forcibly circulated as shown by the arrow to cool the cylinder 7 and cylinder head 8 inside the water jacket, and the warmed cooling water is led to the radiator and cooled by outside air. Note that a thermostat 12 is provided between the water jacket 6 and the radiator 10 to maintain the temperature of the cooling water at an appropriate temperature.

Cooling water in the water jacket 6 of the cylinder block 9 of a multi-cylinder, for example, six-cylinder internal combustion engine flows from the front of the engine to the rear, as indicated by arrows in the schematic cross-sectional view of the cylinder block in FIG.

When detecting knocking in a multi-cylinder internal combustion engine with a single detector, generally a number 2 is used in Fig. 4.
It will be installed at the center of the multi-cylinder as shown in the figure.

The configuration of one embodiment of the knocking detector used in this case, attached to the engine block, is shown as a cross-sectional view in FIG. 21 is a threaded portion 21a
A metal cylindrical housing integrally formed with 2
Reference numeral 2 denotes a disc-shaped vibrating body made of a conductive material, whose entire circumference is fixed to the housing 21, and forms a pressure-receiving surface.
23 is a piezoelectric body fixed to the surface of the vibrating body 22; 24
is the lead wire, 25 is the output terminal, 26 is the output terminal 2
A connector made of an insulator integrally molded with 5, 27
is an O-ring for sealing, and 28 is a gasket for mounting.

The operation of the knocking detector shown in FIG. 5 will be explained. When knocking occurs in the cylinder 7, the cylinder 7 vibrates and the pressure pulsation is transmitted to the cooling water in the water jacket 6 and then to the vibrating body 22 of the detector 2 attached to the cylinder block 9.
When the vibrator 22 moves in response to the pressure pulsation of the cooling water, an AC voltage is generated in the piezoelectric element 23 and a voltage signal is output to the output terminal 25 .

As shown in FIGS. 4 and 5 above, the knocking detector 2 is installed at the center of the six cylinders so that the vibrating body is approximately flush with the wall surface of the cylinder block 9, and knocking occurs from each cylinder. The results of measuring the pressure pulsations are shown in FIG. In Fig. 6, #1 to #6 indicate the cylinder numbers sequentially from the front to the rear of the engine, and S indicates the number of engine cooling water pressure pulsations caused by combustion in a certain knocking state for each cylinder. Take the peak value, find its distribution, and take 5% from the larger peak value. N is the distribution of the peak value of the pressure pulsation coming from each cylinder without knocking. S/M represents the knocking detection sensitivity of each cylinder, and as shown in Figure 6, the knocking detection sensitivity of the cylinder downstream of the flow of cooling water is calculated by taking 3% from the largest value. It was found that the knocking detection sensitivity was inferior to that of the upstream cylinder.

In view of the above points, the present invention averages the knocking detection sensitivity of each cylinder when detecting the knocking of each cylinder from the pressure pulsation of the engine cooling water generated by the knocking of each cylinder in a multi-cylinder internal combustion engine. It is an object of the present invention to provide a knocking detection device that improves the accuracy of knocking detection.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention shown in the drawings will be described. FIG. 7 is a schematic cross-sectional view showing the configuration of an embodiment of the knocking detection device for an internal combustion engine according to the present invention.
The knocking detector 2 is installed at a position downstream from the center position of the six cylinders, between the #4 cylinder and the #5 cylinder, so that the vibrating body is substantially flush with the wall surface of the cylinder block 9. The configuration of the knocking detector 2 may be the same as that shown in FIG.

In the knocking detection device according to the present invention described above, the knocking detection sensitivity characteristics of each cylinder according to the present invention were measured using the same measuring method as the method of measuring the knocking detection sensitivity characteristics of each cylinder shown in FIG. 6, and the results are as follows. As shown in Figure 8, compared to the characteristics shown in Figure 6 above, the knocking detection sensitivity of cylinders #5 and #6 is improved, the knocking detection sensitivity is averaged as a whole, and the knocking detection accuracy is improved. There is.

As mentioned above, the knocking detection device according to the present invention can easily improve the knocking detection sensitivity by installing the knocking detector on the cylinder block at a position downstream of the flow of cooling water from the center position of the multi-cylinder. This has the great effect of improving the knocking detection sensitivity of cylinders with poor performance, and improving the knocking detection accuracy of multiple cylinders.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the knock feedback ignition system, Fig. 2 is a diagram of the installation state of the knocking detector, Fig. 3 is a vertical cross-sectional schematic diagram of a water-cooled cooling system for an internal combustion engine, and Fig. 4 is a 6-cylinder internal combustion engine. FIG. 5 is a schematic cross-sectional view of a cylinder block of an engine, and FIG. 5 is a cross-sectional view of a knocking detector attached to the engine block for explaining the present invention. FIG. 6 is a schematic cross-sectional view of the knocking detector shown in FIG. The knocking detection sensitivity characteristics of each cylinder measured by the detector at the center position of the six cylinders for each cylinder. Figure 7 shows the knocking detection device for an internal combustion engine according to the present invention, and Figure 8 shows the knocking detection according to the present invention. FIG. 3 is a knocking detection sensitivity characteristic diagram of each cylinder measured in the apparatus. 2... Knocking detector, 6... Water jacket, 7... Cylinder, 9... Cylinder block, 22... Vibrating body, 23... Piezoelectric body, 21...
Housing, 21a...screw part.

Claims (1)

[Scope of utility model registration request] In a knocking detection device that detects knocking in a multi-cylinder internal combustion engine based on pressure pulsations in the engine cooling water, the mounting position of the pressure detection means for detecting pressure pulsations on the engine block is adjusted from the center position of the multi-cylinder to the engine cooling water flow. A knocking detection device for an internal combustion engine, characterized in that the knocking detection device is located downstream.