JPH0681925B2 - Knocking detection device for internal combustion engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knocking detection device that processes a signal from a means for detecting vibration of an engine to detect occurrence of knocking.

<Prior Art> Conventional knocking detection and ignition timing control based thereon are performed by a device as shown in FIG. 4 (see Japanese Patent Laid-Open No. 59-49369).

The cylinder head of the V-type 6-cylinder engine 1 is equipped with a knocking sensor 2 that detects the vibration of the cylinder head wall and outputs it as a voltage. The high-frequency wave corresponding to the middle knocking signal from the knocking sensor 2 Only the component is extracted by the bandpass filter 3.

Next, the rectifying / integrating circuit 4 integrates the signal from the bandpass filter 3 only in a predetermined crank angle section in which knocking frequently occurs, and does not perform integration in other sections, and performs A / D conversion in the next stage. Output to the container 5.

A knocking determination unit 6 compares a signal directly input from the A / D converter 5 with a signal obtained by averaging the signal for each cylinder according to the cylinder determination signal.

Then, when knocking occurs, the integrated value of the signal in the integration section exceeds the value obtained by averaging, and it is determined that knocking is present. In other cases, it is determined that knocking is absent.

Based on this determination, the ignition timing correction amount calculation unit 7 for each cylinder
However, the correction amount of the ignition timing is set for each cylinder. For example, when knocking is detected in the first cylinder and the second cylinder as shown in the figure, the ignition timings of these cylinders are retarded by a predetermined amount (retard), and it is determined that there is no knocking in the third cylinder.
The ignition timing of the cylinder or the like is set by advancing by a predetermined amount.

Next, in the ignition timing calculation unit 8, the basic ignition timing ADV ₀ is searched for from the map stored in advance in the ROM on the basis of the basic injection amount T _P of the fuel representing the load of the engine and the engine rotation speed N. In addition, the ignition timing correction amount calculation unit 7
The final ignition timing is set by adding the correction amount calculated in.

Based on the set ignition timing, the ignition timing drive circuit 9 outputs an ignition signal to the corresponding ignition cylinder of the engine.
As a result, ignition is performed at the set ignition timing.

<Problems to be Solved by the Invention> However, in such a conventional device, a bandpass filter, a rectifying / integrating circuit, and an A / D are provided as hardware for processing a knocking signal in a stage preceding the knocking determination unit 5. In addition to the need for a converter, the cost for the hardware itself is high, and the cost required for knocking control is considerably high due to factors such as an increase in manufacturing cost due to an increase in the number of bandpass filter adjustment steps.

The present invention has been made in view of such conventional problems, and provides a knocking signal processing device for an internal combustion engine that solves the above problems by executing knocking signal processing by software as much as possible. The purpose is to do.

<Means for Solving the Problems> Therefore, according to the present invention, as shown in FIG. 1, a vibration detecting means for detecting vibration generated in the engine and outputting it as a voltage signal, and a crank angle section in which knocking frequently occurs. Knocking occurrence section detection means for detecting, A / D converter for A / D conversion the signal from the vibration detection means, the section detected by the knocking occurrence section detection means, from the other section, the vibration Conversion frequency control means for largely controlling the frequency of converting the signal from the detection means by the A / D converter, signal storage means for storing the signal converted by the A / D converter, and the signal storage means Knocking discrimination means for averaging the stored signals to discriminate the presence or absence of knocking.

<Operation> The vibration detection means detects the vibration generated in the engine including the vibration caused by knocking, and outputs it as a voltage signal to the A / D converter.

The knocking occurrence section detection means detects a crank angle section in which knocking occurs at a high frequency, whereby the conversion frequency control means largely controls the frequency of A / D conversion by the A / D converter in the detection section. The frequency of A / D conversion is controlled to be small in other sections.

The signal thus A / D converted is stored by the signal storage means, the stored signal is averaged by the knocking determination means, and the presence or absence of knocking is determined based on the processed signal. .

<Example> Below, the Example of this invention is described based on drawing.

In FIG. 2 showing the structure of one embodiment, the same components as those shown in FIG. 4 are designated by the same reference numerals.

In the figure, a knocking sensor 2 as a vibration detecting means
The voltage signal from is output to the A / D converter 11.

The A / D conversion frequency control unit 12 inputs a signal from a crank angle sensor 21 (generally provided for fuel injection control etc.) that outputs a signal for each predetermined crank angle of the engine 1,
A section with a high knocking occurrence frequency is detected, and the A / D conversion operation by the A / D converter 11 is performed with a high frequency in the section, and is performed with a low frequency in other sections. That is, this function combines the functions of the knocking occurrence section detection means and the conversion frequency control means.

The converted digital signal is peak-held (holds only the maximum value) and stored in the signal peak-hold processing unit 13 at the next stage.

The stored signal, in the knocking determination unit 14,
Averaging processing, which will be described later, is performed on the ones stored in the sections with high A / D conversion frequency and those stored in other sections, and the processed ones are compared with each other to knock. It is determined whether or not is generated.

Thereafter, the ignition timing correction amount calculation unit 7 sets the correction amount of the ignition timing for each cylinder according to the presence or absence of knocking, and the ignition timing calculation unit 8 adds the correction amount to the basic ignition timing ADV _0. The final ignition timing is set according to the above, and the ignition timing drive circuit 9 outputs an ignition signal to the corresponding ignition cylinder of the engine to control the ignition at the set ignition timing as in the conventional case. Done.

Next, the detection of knocking will be described in more detail with reference to the flowchart shown in FIG.

In step (denoted as S in the figure) 1, the crank angle sensor
Based on the signal from 21, it is determined whether or not a section with a high knocking frequency, for example, a crank angle section of 10 ° to 57 ° after top dead center. This part corresponds to knocking occurrence section detection means.

If it is determined that the section has a high knocking occurrence frequency, the process proceeds to step 2, and it is determined whether or not it coincides with the high-frequency A / D conversion timing set in accordance with the section.

Then, when they match, the routine proceeds to step 3, where the voltage signal from the knocking sensor 2 is A / D converted by the A / D converter 11.

In step 4, each maximum value in the digital signal converted into this section is stored in the memory N _i . The determination of the maximum value is performed when the change in the signal value changes from increasing to decreasing.

When it is determined in step 1 that the frequency of knocking occurrence is low, the process proceeds to step 5 and it is determined whether or not it is immediately after the transition from the high frequency interval to the low frequency interval.

Then, when the determination is NO, the process proceeds to step 6 and it is determined whether or not the A / D conversion timing set at a low frequency matches.

If they match, proceed to step 7 and knock sensor 2
The voltage signal from the A / D converter 11 is A / D converted.

Next, in step 8, the signal data in the section is weighted and averaged.

In step 9, the processed data is stored in the memory BGL.

If the determination in step 5 is YES, the process proceeds to step 10, and the average value N _iMEAN of the i pieces of data N _i stored in step 4 is calculated.

Next, in step 11, the weighted average value BGL is compared with the average value N _iMEAN .

If the latter value is larger than the former value by the set value or more, the routine proceeds to step 12, where it is determined that knocking is present, and if not, the routine proceeds to step 13 where it is determined that there is no knocking. Since the weighted average value BGL in a region other than the knocking occurrence section is a value close to the bias voltage from the knocking sensor 2 when vibration does not occur, there is knocking when the average value N _iMEAN is sufficiently large. Can be determined. However, for the sake of simplicity, the weighted average value BGL may not be calculated and may be compared with a known bias voltage. In this case, A / D conversion may not be performed at all in the section where the knocking occurrence frequency is low. That is, the present invention includes one in which the frequency of A / D conversion is set to 0 in the section where the knocking occurrence frequency is low.

Here, the steps 2, 3, 5, 6, and 7 correspond to the conversion frequency control means, the step 4 corresponds to the signal storage means,
Steps 8, 9, 10, 11, 12, and 13 correspond to knocking determination means.

With such a configuration, in addition to the A / D converter, all signal processing for knocking detection can be performed by software, and the frequency of A / D conversion is limited to a specific section where knocking easily occurs. Since it can be increased, there is a margin to sufficiently perform calculations for other control of the internal combustion engine in other sections, and it is not necessary to provide a dedicated A / D converter with a high calculation speed.

Therefore, it is possible to significantly reduce the cost which was conventionally required for detecting the knocking and the cost for adjusting the hardware, and the adjustment is not necessary.

<Effects of the Invention> As described above, according to the present invention, the hardware for knocking detection can be greatly simplified, the cost can be significantly reduced, and the hardware adjustment is not required. Is.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 is
FIG. 3 is a diagram showing a configuration of an embodiment of the present invention, FIG. 3 is a flowchart showing a knocking detection routine of the same embodiment, and FIG. 4 is a diagram showing a configuration of a conventional example. 1 ... V-6 cylinder engine, 2 ... knocking sensor, 11 ...
… A / D converter, 12 …… A / D conversion frequency control section, 13 …… Signal peak hold processing section, 14 …… Knocking judgment section

Claims (1)

[Claims] 1. A vibration detecting means for detecting a vibration generated in an engine and outputting it as a voltage signal, a knocking occurrence section detecting means for detecting a crank angle section in which knocking frequently occurs, and a signal from the vibration detecting means. A / D converter for A / D conversion, the section detected by the knocking occurrence section detection means, from other sections, the frequency of converting the signal from the vibration detection means by the A / D converter. A conversion frequency control means for largely controlling, a signal storage means for storing the signal converted by the A / D converter, and a knocking for averaging the signals stored in the signal storage means to determine the presence or absence of knocking. A knocking detection device for an internal combustion engine, comprising: a determination means.