JPH0681924B2 - 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, as shown in FIG. 1, the present invention detects a vibration occurring in an engine and outputs it as a voltage signal, and a predetermined crank that frequently causes knocking. Knocking occurrence section detecting means for detecting an angular section, an A / D converter for A / D converting the signal from the vibration detecting means, and a section detected by the knocking occurrence section detecting means are other sections, Conversion frequency control means for largely controlling the frequency of converting the signal from the vibration detection means by the A / D converter, signal storage means for storing the signal converted by the A / D converter, and the signal storage An extreme value storage means for discriminating and storing at least one of the maximum value and the minimum value in the predetermined crank angle section from the signal stored in the means; and the maximum value and the maximum value stored for the discrimination. And at least one value, configured to include a, a knocking determining means for determining whether knocking by comparing the A / D converted signal value at a crank angle interval other than the predetermined crank angle interval.

<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 predetermined crank angle section in which knocking is frequently generated, whereby the conversion frequency control means increases the frequency of A / D conversion by the A / D converter in the predetermined 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, and among the stored signals, at least one of the maximum value and the minimum value in the predetermined crank angle section is stored by the extreme value storage means. It is determined and stored.

The knocking determination means compares at least one of the maximum value and the minimum value determined and stored with the A / D converted value in a crank angle section other than the predetermined crank angle section, and determines the magnitude of the deviation or the like. Determine if there is knocking.

<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 predetermined section with a high knocking occurrence frequency is detected, and the A / D conversion operation by the A / D converter 11 is performed with high frequency in the section and is performed with 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.

Among the converted digital signals, those in a predetermined section in which the knocking occurrence frequency is high are stored in the signal peak hold processing unit 13 after being peak-held (holding only the maximum value and the minimum value).

On the other hand, the signals stored in the sections other than the predetermined section are averaged by the averaging unit 14.

Then, the maximum value and the minimum value stored in the signal peak hold processing unit 13, and the value averaged in the averaging processing unit 14 are input to the knocking determination unit 15, and in the knocking determination unit 15, both Are compared, and if there is a large deviation between the maximum and minimum values and the averaged value, it is determined that knocking is present, and otherwise, it is determined that there is no knocking.

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 process proceeds to step 3, where the voltage signal from the knocking sensor 2 is A / D converted by the A / D converter 11, and the A / D conversion value of the section is sequentially stored in the RAM.
That is, this function and the RAM correspond to the signal storage means.

In step 4, it is determined whether or not it is the maximum value in the digital signals converted in this section. If it is determined to be the maximum value, the process proceeds to step 5 and the value is stored in the memory DMAX.

When the determination in step 4 is NO, the process proceeds to step 6, and it is determined whether or not it is the minimum value in the converted digital signals. If it is determined to be the minimum value, the process proceeds to step 7 and the value is determined. Is stored in the memory DMIN.

The functions of these steps 4 to 7 correspond to the extreme value storage means.

When it is determined in step 1 that the frequency of occurrence of knocking is low, the process proceeds to step 8 and it is determined whether or not it is immediately after shifting from a frequency of high frequency to a frequency of low frequency.

Then, if the determination is NO, the process proceeds to step 9, and it is determined whether or not the A / D conversion timing set at a low frequency matches.

The functions of steps 2, 3, and 9 correspond to conversion frequency control means.

When they match, proceed to step 10 and knock sensor 2
The voltage signal from is A / D converted by the A / D converter 11, and the A / D conversion value of the section is sequentially stored in the RAM. That is,
This function also corresponds to the signal storage means.

Next, in step 11, the signal data of the section is weighted and averaged.

In step 12, the processed data is stored in the memory BGL.

If the determination in step 8 is YES, the process proceeds to step 13, and the maximum value data DMAX stored in step 5 is compared with the weighted average processed value BGL. If the former value is larger than the latter value by the set value or more, the process proceeds to step 14, but if not, the process proceeds to step 15 and it is determined that there is no knocking.

Next, at step 14, the minimum value data DMIN stored at step 7 is compared with the weighted average processed value BGL. When the former value is smaller than the latter value by the set value or more, the routine proceeds to step 19, where it is determined that knocking is present, and when not, the routine proceeds to step 15 where it is determined that there is no knocking.

Here, the part from step 11 to step 16 corresponds to knocking determination means.

Since the weighted average value BGL outside the knocking occurrence section is a value close to the bias voltage from the knocking sensor when no vibration occurs, the maximum value DMAX is a sufficiently large value and the minimum value DMIN. When is sufficiently small, it is determined that the amplitude of the engine vibration has a magnitude corresponding to that generated when knocking occurs, and it is determined that knocking is present. However, for simplicity, the weighted average value BGL
It is also possible to compare with a bias voltage which is known in advance without obtaining the above, in which case A / D conversion in the section where the knocking occurrence frequency is low need not be performed at all. That is, the present invention is
0 in the frequency of A / D conversion in the section where the knocking frequency is low
It includes the following.

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.

In the case of the present embodiment, the bias voltage of the knocking sensor is set to a large value to determine the presence or absence of knocking by capturing the maximum value and the minimum value. The configuration may be such that the knock is determined by rectifying the wave and capturing only the maximum value or the minimum value.

<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 THE DRAWINGS FIG. 1 is a block diagram showing the configuration of the present invention, and FIG.
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 …… Averaging processing section, 15 …… 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 predetermined crank angle section in which knocking frequently occurs, and the vibration detecting means. A / D converter for A / D converting the signal of, and the section detected by the knocking occurrence section detection means, the signal from the vibration detection means is converted by the A / D converter from other sections. The conversion frequency control means for controlling the frequency to a large degree, the signal storage means for storing the signal converted by the A / D converter, and the maximum in the predetermined crank angle section among the signals stored in the signal storage means. An extreme value storage means for discriminating and storing at least one of a value and a minimum value, at least one of the maximum value and the minimum value discriminated and stored, and other than the predetermined crank angle section. Device for detecting knocking in an internal combustion engine, characterized in that configured to include a knocking determining means for determining whether knocking by comparing the A / D converted signal values at rank angle intervals.