JPH01285665A - Knock control device - Google Patents

Abstract

PURPOSE:To perform correct knock detection over the whole rotating speed region of an engine by optionally changing and setting the start time and width of a knock gate indicating the angle where knocking is generated based on the rotating speed or the like of the engine. CONSTITUTION:The knock signal from a knock sensor 1 is inputted to a comparing circuit 3 via a BPF 2. The rotation signal from a distributor 7 is inputted to a microcomputer 6 via a wave-form shaping circuit 8. The microcomputer 6 outputs the noise level and the knock judgment level to the comparing circuit 3 via a DA converter or a ladder resistor 5 and a buffer 4. When the output signal of the comparing circuit 3 is inputted to the microcomputer 6 and the microcomputer 6 is interrupted by a knock gate, a knock is judged. In this case, the microcomputer 6 optionally changes and sets the start angle and completion angle and the width of the knock gate based on the rotating speed respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a knock control device that detects knocking in an internal combustion engine and controls the amount of retardation of ignition timing.

(Prior Art) Conventionally, this type of knock control device uses a microcomputer (hereinafter also referred to as microcomputer) in order to improve the accuracy of one ignition timing, and has a configuration as shown in Figure 1. . 1 is a knock sensor attached to the engine block.

2 is a load impedance of the sensor, a band pass filter, etc. (hereinafter referred to as BPF), and 3 is a comparison circuit.

4 is a buffer, 5 is a ladder resistor or OA converter,
6 is a microcomputer. 7 is a distributor, 8 is a waveform shaping circuit, and 9 is an igniter.

Next, the operation of the above conventional example will be explained. In FIG. 1, a knock sensor 1 converts engine vibration into an electric signal, and outputs it to a comparator circuit 3 via a BPF 2. On the other hand, the signal with rotation information from the distributor is passed through the waveform shaping circuit 8 and sent to the microcomputer 6 as a signal indicating the ignition and charging start on/off as shown in parentheses (,) in Fig. 2. is input.

The microcomputer 6 creates a knock gate indicating the angle at which knocking occurs and a noise gate indicating the angle at which knocking does not occur, as shown in FIG. 2(b), from the signal (a).
Depending on this, it is determined whether to permit the output of the comparison circuit 3 (an interrupt from the perspective of the microcomputer 6).

The noise level described above, in which a noise level is calculated based on the number of interruptions occurring in the noise gate, a knock judgment level is calculated from this noise level, and a knock judgment is performed based on the number of interruptions during the knock gate.

The knock determination level is sent as a digital value from the port of the microcomputer 6 to the ladder resistor or the DA converter 5, converted to an analog value, and sent as a signal (d) to the comparison circuit 3 via the buffer 4. The comparison circuit 3 compares the signal (C) from the knock sensor 1 and the signal (d) from the buffer 4 and sends an output signal (e) to the microcomputer 6.

The output signal (e) of the comparator circuit 3 is input to the microcomputer 6 and
When the interruption is permitted, the interruption at the knock gate is determined to be a knock, and the retard control is performed depending on the presence or absence of this knock, and the result is sent to the igniter 9 as a signal (f) as shown in Fig. 2. .

Figure 3 shows an outline of the operation flow. Information such as gates is stored in the ROM in the form of angles. Multiply the time per @ by the angle, and put the value in the register. When this register matches the free running counter, an internal interrupt is generated.

(Problem M to be solved by the invention) However, in the conventional knock control device described above, the angle of the knock gate is generally set at about 60' from top dead center, and then the noise gate is set at about 30 degrees. It is set. As the speed increases, the time delay for the knocking phenomenon inside the cylinder to transmit vibrations to the knock sensor increases in terms of angle, and the length of the tail of the signal due to the responsiveness of the knock sensor increases in terms of angle. There was a problem that knock detection could not be performed properly.

The present invention solves the above-mentioned conventional problems.

It is an object of the present invention to provide a knock control device that can accurately detect knocking over all rotational speeds.

(Means for Solving the Problems) In order to achieve the above object, the present invention is such that the starting angle, ending angle, and width of the knock gate are changed depending on the number of rotations.

(Function) The present invention has the following effects due to the above configuration. That is, at all rotational speeds and at the angle at which knocking occurs at the knock gate.

And noise other than knocking (e.g. ignition noise, etc.)
Since the angle can be set to a small number, knocking can be detected correctly over all rotational speeds, especially at high speeds.

(Example) The present invention is applied to the knock control device shown in FIG. 1, for example,
The control section of the microcomputer 6 is provided with a control means that can change and set the angle at which the knock gate starts and the width of the knock gate.

FIG. 4 shows an embodiment of the present invention, in which RO
The zero rotation speed or period, which is data contained in M (table), corresponds to a predetermined address. In the example shown in FIG. 4, when the address is n, the period is 3.75mXn, the period from one ignition to ignition is measured, and the value obtained by dividing this by 3.75m is used as the address.

Then, the corresponding gate information An”, Bn’
as data.

Take advantage of this.

According to the above embodiment, when an ignition interrupt occurs.

First, measure the cycle from the previous ignition to the current ignition.

Divide this period by 3.75ais. This result is an address, and the data corresponding to this address is used.

For example, if it is 7.5mm, the result of dividing by 3.75m is 2, so the rotation speed is 400Orpm, the distance from 1st ignition to the start of the knock gate is 20°, and the knock gate width is 60°.
becomes. By setting this data.

The knock gate can be set in advance in a place where knocking occurs and where there is little noise.

As described above, according to the fifth embodiment, the knock gate can be arbitrarily set according to each rotation speed, so that accurate knock detection can be performed over all rotation speeds.

In addition, the following points are considered to be the same as the present invention: (1) changing the starting angle of the noise gate and the noise gate width according to the rotation speed; (2) information other than the rotation speed 1, for example, intake pressure, etc. Change the angle 9 width at which the knock gate and noise gate start according to the value of.

etc.

(Effects of the Invention) As is clear from the above embodiments, the present invention changes the knock gate and noise gate based on information about the engine, such as the number of revolutions, so as to best meet the purpose.

This has the effect of accurately detecting knocking over the entire rotation speed.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a conventional knock detection device to which the present invention can be applied, FIG. 2 is a signal waveform diagram of each part of FIG. 1, FIG. 3 is a schematic flow chart, and FIG. 4 is a diagram of the present invention. FIG. 2 is a diagram showing the contents of a data table written in a ROM of a microcomputer in an embodiment of the present invention. 1...knock sensor, 2...sensor load circuit,
Bandpass filter, etc., 3... Comparison circuit, 4...
・Buffer, 5... Ladder resistor or DA converter, 6
... Microcomputer, 7 ... Distributor, 8 ... Waveform shaping circuit, 9 ... Igniter, Patent applicant Matsushita Electric Industrial Co., Ltd. No. 18 Fig. 2 Fig. 4

Claims (1)

[Claims] a means for detecting engine vibration; a means for extracting engine rotation information; and a signal representing a comparison result between the signal from the vibration detection means and a pre-calculated knock determination level, which is generated from the rotation information. A knock control device comprising: means for making a knock determination based on the number of interrupts input during a period of a knock gate indicating an angle and performing retarded advance angle control; A knock control device characterized in that it is provided with a control means for setting.