JPH06100173B2 - Knock control device for internal combustion engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a knock control device for an internal combustion engine for controlling knocking of the internal combustion engine.

[Prior Art] FIG. 6 is a block configuration diagram showing a configuration of a conventional knock control device for an internal combustion engine. In the figure, (1) is a knock sensor that is attached to an engine and detects knocking of the engine, (2) is a bandpass filter that filters the band of the output signal from the knock sensor (1), and (3) is a gate circuit. Then, the output signal from the band pass filter (2) is gated by the mask signal from the microcomputer (9). (4) is a BGL circuit, which forms a background level (BGL) based on the output signal from the gate circuit (3). A comparator (5) compares the output signal from the gate circuit (3) with the output signal from the BGL circuit (4).
(6) is an integrator, which integrates the output signal from the comparator (5) and is reset by a reset signal from a microcomputer (9) described later.

The knock detection circuit (7) is configured by means of the above means except the knock sensor (1).

Reference numeral (8) is an A / D converter, which converts an analog signal from the integrator (6) into a digital signal so as to be taken into the microcomputer (9). Microcomputer (9)
Includes a delay angle correction processing means (10) for performing a delay angle correction process based on the output signal from the A / D converter (8).

FIG. 7 is a diagram showing operation waveforms of the respective parts of FIG.

The conventional knock control device for an internal combustion engine is configured as described above, and the detection signal from the knock sensor (1) (Fig. 7 (a)) is used.
The reference signal is input to the band pass filter (2), a predetermined band is filtered, and the filtered signal is supplied to the gate circuit (3). Since the mask signal (see FIG. 7B) is applied to the gate circuit (3) from the microcomputer (9), the output signal of the bandpass filter (2) is masked for a predetermined period, and the gate circuit (3) is masked. The output signal of (3) is as shown in FIG. 7 (c). The output signal of the gate circuit (3) is applied to one input of the comparator (5). The output signal of the gate circuit (3) is applied to the BGL circuit (4),
A predetermined background level is formed as shown in FIG. This background level is applied to the other input of the comparator (5) and compared with the output signal of the gate circuit (3). The signals obtained from the comparator (6) are integrated by the integrator (6) to obtain an integrated value as shown in FIG. 7 (e). Since the integrated value is obtained for each cylinder, a reset signal is supplied to the integrator (6) from the microcomputer (9) for each cylinder. Integrator (6) obtained in the integral value voltage digital signal (V _R) of the microcomputer with an A / D conversion by the A / D converter (8) (9)
Then, the knock correction delay angle control angle (Δθ _R ) is obtained by the delay angle correction processing means (10) from the following equation and controlled.

Δθ _R = V _R × NN: correction factor [Problems to be solved by the invention] In the conventional knock control device for an internal combustion engine as described above, the circuit is complicated because the hardware performs signal processing up to knock determination. Therefore, the burden on the hardware for control is large,
There was a problem that the cost was high.

The present invention has been made in order to solve the above problems, and has a small load on the hardware part, a simple circuit, and a knock determination process performed by a microcomputer. The purpose is to obtain a knock control device.

[Means for Solving the Problems] A knock control device for an internal combustion engine according to the present invention includes a detector for detecting a knocking state of the engine, a peak hold means for obtaining a peak value signal from the detector output, and the detector. Averaging means for obtaining an averaged signal from the output, threshold setting means for setting a knock determination threshold from the averaged signal from the averaging means, and knock determination by comparing the peak value signal level with the threshold. , A calculation means for calculating a knock control amount based on the difference between the peak value signal level and the threshold, and a retard correction processing means for retarding the ignition timing based on the knock control amount. .

[Operation] In the present invention, the knock control amount calculated by the calculation means is determined by normalizing the difference between the peak value and the threshold with a coefficient obtained according to the threshold level.

[Embodiment] FIG. 1 is a block diagram showing a knock control device for an internal combustion engine according to an embodiment of the present invention. In the figure, (1),
(2), (8) and (10) are the same as the conventional ones.
(11) is a peak hold circuit, which peak-holds the output signal from the bandpass filter (2) to obtain a peak value signal. Further, a reset signal is applied to the peak hold circuit (11) from a microcomputer (9A) described later only during a period when knock does not occur. (12) is an averaging circuit, which averages the output signals from the bandpass filter (2) to obtain an average value signal. Bandpass filter (2),
A knock interface circuit (13) is composed of the peak hold circuit (11) and the averaging circuit (12).
(14) is amplification / offset addition means, which is an averaging circuit (1
The signal (V _A ) obtained by converting the average value from 2) by the A / D converter (8) is amplified and offset is added to form the knock discrimination threshold (V _TH ). Reference numeral (15) is a comparison means, which is a signal (V _P ) obtained by converting the peak value from the peak hold circuit (11) by the A / D converter (8) and the knock discrimination threshold (V _TH ). And are compared and knock discrimination processing is performed. The microcomputer (9A)
Amplification / offset addition means (14) and comparison means (15)
And a retard correction processing means (10).

FIG. 2 is a diagram showing operation waveforms of each part of FIG.

FIG. 3 is a diagram showing an operation flowchart of the microcomputer.

In the knock control device for an internal combustion engine configured as described above, the output signal of the knock sensor (1) shown in FIG. 2 (b) is band-pass filtered by the band pass filter (2) and the peak hold circuit ( 11) and averaging circuit (12)
Thus, the peak value as shown in FIG. 2 (c) and the average value as shown in FIG. 2 (d) are obtained for each cylinder. Since the peak hold reset signal as shown in FIG. 2 (a) is supplied from the microcomputer (9A) only during the period when knock does not occur, this peak value is obtained only during the period when knock occurs.

In response to the peak value and the average value, the microcomputer (9A) performs processing steps as shown in FIG.
Performs knock determination and retard correction processing.

First, in step S1 in FIG. 3, the peak hold signal is converted by the A / D converter (8) to obtain the signal (V _P ). Next, in step S2, a reset signal is supplied from the microcomputer (9A) to the peak hold circuit (11). Then, in step S3, the above-mentioned averaged signal is converted by the A / D converter (8) to obtain the signal (V _A ). This conversion signal (V _A ) is amplified K times by the amplification / offset addition means (14), and V _ofs offset is added to the knock discrimination threshold.
Calculate V _TH = V _A × K + V _ofs ). Threshold V that in step S5 obtained in V _P and S4 determined at step S1
Knock discrimination processing is performed by comparing with _TH . When this comparison (V _K = V _P −V _TH ) is positive in step S6, it is determined that there is knocking, the process proceeds to step S8, the retard correction processing is performed, and the knock retard control angle (retard amount) Δθ _R = V _K × L = (V _P −V _TH ) × L (where L is a correction factor) is calculated. If the above comparison is not positive in step S6, it is determined that there is no knocking, and the process proceeds to step S7, in which the retard angle amount Δθ _R = O is set. Next, step S9
Then, the knock correction delay amount θ _R = θ _R + Δθ _R is calculated based on the delay amount obtained in the above step.

Fig. 4 shows the characteristics of the threshold (V _TH ) obtained from the peak hold output signal ( _VP ) and the averaged signal ( _VA ) at the same knock intensity with respect to the rotational speed. As can be seen from this characteristic, V _K = V _P −V _TH is higher at high rotation than at low rotation, and the calculation of the control amount Δθ _R is performed as described above with Δθ _R = V _K × L = (V _P If −V _TH ) × L, the control amount Δθ _{R at the} same knock strength is large at high rotation and small at low rotation, and good controllability cannot be obtained.
Therefore, in order to obtain good controllability as in the present invention, instead of step S8 in FIG. 3, the retard correction processing by the knock determination threshold in step S8A in FIG. 5 may be performed. That is, the knock control amount Δθ
_R is determined and controlled by the difference between the peak hold value ( _VP ) and the threshold ( _VTH ) and the coefficient (L '/ _VTH ) normalized by the threshold level as shown in the following formula.

_{Δθ R = V K × (L} '/ V TH) = (V P -V TH) × (L' /
V _TH ) [Effects of the Invention] As described above, the present invention provides a detector for detecting the knocking state of an engine, a peak hold means for obtaining a peak value signal from the detector output, and an averaging signal from the detector output. And threshold setting means for setting a knock discrimination threshold from the averaging signal from the averaging means, knock comparison by comparing the peak value signal level with the threshold, and the peak value The comparison means, the threshold generation means, the delay means, the calculation means for calculating the knock control amount on the basis of the difference between the level and the threshold, and the retard correction processing means for correcting the ignition timing on the basis of the knock control amount. Since the angle correction means and the like are configured by a microcomputer, the load on the hardware part is small, the circuit is simple, and Since the microcomputer performs the knock discrimination processing, the knock discrimination control for each cylinder can be performed at a low cost, and a device with high controllability such as fine-grained retard correction according to the knock signal can be provided. There is an effect that can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a knock control device for an internal combustion engine according to an embodiment of the present invention, FIG. 2 is an operation waveform diagram of each part in FIG. 1, and FIG. 3 is an example of an operation flowchart of a microcomputer. , Fig. 4 is a characteristic diagram for the engine speed of the threshold at the same knock intensity, Fig. 5
FIG. 6 is a diagram showing another example of the operation flow chart of the microcomputer, FIG. 6 is a block diagram of a conventional knock control device for an internal combustion engine, and FIG. 7 is an operation waveform diagram of each part of FIG. In the figure, (1) ... knock sensor, (2) ... bandpass filter, (9A) ... microcomputer,
(8) ... A / D converter, (10) ... delay angle correction processing means,
(11) …… Peak hold circuit, (12) …… Averaging circuit, (13) …… Knock interface, (14) …… Amplification / offset / addition means, (15) …… Comparison means. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A detector for detecting a knocking state of an engine.
And the peak signal that obtains the peak value signal from this detector output.
Means for obtaining an averaged signal from the detector output
Knock from the averaging means and the averaging signal from this averaging means
Threshold setting means to set the discrimination threshold
And the peak value signal level and the threshold
Knock discrimination is performed by comparison, and the peak value signal level and
Knock control amount is calculated based on the difference between the thresholds
And an ignition timing based on the knock control amount.
And a delay angle correction processing means for correcting the delay angle.
The controlled variable is the difference between the peak value and the threshold.
It is possible to normalize with the coefficient obtained according to the threshold level.
Internal combustion engine characterized by being determined by
Seki knock control device.