JPH01318744A - Device for detecting knocking of internal combustion engine - Google Patents

Abstract

PURPOSE:To simplify hardware for detecting knocking by a method wherein at least one of the maximum and the minimum within a specified crank angle range is compared with a signal value outside the specified crank angle range to identify existence of knocking. CONSTITUTION:When the output signal of a vibration detecting device A which detects vibration caused in an engine is input to a signal storage device C via an A/D converter B, the detection signal of a crank angle range whose knocking occurrence is frequently detected by a detecting device D is controlled by a conversion frequency controlling device E so that it is more frequently converted than those of other ranges. At least one of the maximum and the minimum within a specified crank angle range among said stored signals is identified and stored by an external value storing device F. The stored value and a signal value of a crank angle range outside the specified crank angle range are compared by a knocking identification device G so as to identify whether or not knocking occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a knocking detection device that detects the occurrence of knocking by processing a signal from a means for detecting engine vibration.

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

The cylinder head of the V-type six-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. Only the components are extracted by the bandpass filter 3.

Next, the rectifying/integrating circuit 4 integrates the signal from the pan-pass filter 3 only in a predetermined crank angle section where knocking occurs frequently, and does not integrate the signal in other sections, and performs A/D conversion in the next stage. Output to device 5.

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

When knocking occurs, the integral value of the signal in the integration interval exceeds the averaged value and it is determined that knocking is present, and at other times it is determined that there is no knocking.

Based on this determination, the ignition timing correction amount calculation unit 7 for each cylinder sets the ignition timing correction amount for each cylinder.

For example, as shown in the figure, if knocking is detected in the first and second cylinders, the ignition timing of these cylinders is retarded by a predetermined amount, and the ignition timing of the third cylinder, which was determined to have no knocking, is retarded by a predetermined amount. The ignition timing of cylinders, etc. is advanced by a predetermined amount.

Next, the ignition timing calculating section 8 determines the basic ignition timing ADV based on the basic injection amount Tp of fuel representing the engine load and the engine rotational speed N. is searched and determined from a map stored in advance in the ROM, and the final ignition timing is set by adding to this the correction amount calculated by the ignition timing correction amount calculation section 7.

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, the hardware for processing the knocking signal at the stage before the knocking determination unit 5 includes a bandpass filter, a rectifier/integrator circuit, and an A/D. A converter is required, which increases the cost of the hardware itself, and the manufacturing cost increases due to the increased man-hours required to adjust the bandpass filter, making the cost required for knocking control considerably large.

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

<Means for Solving the Problems> For this reason, the present invention, as shown in FIG. knocking occurrence section detection means for detecting the corner section; an A/D converter for A/D converting the signal from the vibration detection means; and the section detected by the knocking occurrence section detection means is selected from other sections. a conversion frequency control means for greatly controlling the frequency at which the signal from the vibration detection means is converted by the A/D converter; a signal storage means for storing the signal converted by the A/D converter; and the signal storage. extreme value storage means for determining and storing at least one of a maximum value and a minimum value in the predetermined crank angle section from among the signals stored in the means; and at least one of the determined and stored maximum value and minimum value. and a knocking determination means for determining the presence or absence of knocking by comparing A/D converted signal values in crank angle intervals other than the predetermined crank angle interval.

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

The knocking occurrence section detection means detects a predetermined crank angle section in which knocking occurs frequently, and the conversion frequency control means increases the frequency of A/D conversion by the A/D converter in the predetermined section. Control II: In other sections, the frequency of A/D variations is controlled to be small.

The A/D converted signal is stored in the signal storage means, and at least one of the maximum value and the minimum value in the predetermined crank angle section among the stored signals is stored in the extreme value storage means. It is determined and stored.

The knocking determination means compares at least one of the maximum value and minimum value stored for discrimination with an A/D conversion value in a crank angle section other than the predetermined crank angle section, and determines the knocking according to the magnitude of the deviation, etc. Determine whether there is knocking.

<Example> Embodiments of the present invention will be described below based on the drawings.

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

In the figure, a knocking sensor 2 as vibration detection means is shown.
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 at every predetermined crank angle of the engine 1, and detects when knocking occurs. A predetermined section with a high frequency is detected, and the A/D converter 11 performs the A/D conversion operation at a high frequency in the section, and performs the A/D conversion operation at 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 in the predetermined section where the knocking frequency is high is stored in the signal peak hold processing section 13 with the peak held (only the maximum value and minimum value are held).

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

Then, the maximum value and minimum value stored in the signal peak hold processing section 13 and the value averaged in the averaging processing section 14 are manually input to the knocking determination section 15.
The knocking determination unit 15 compares the two, and when there is a large deviation between the maximum value and the minimum value and the averaged value, it is determined that there is knocking,
In other cases, it is determined that there is no knocking.

Thereafter, the ignition timing correction amount calculation unit 7 sets the ignition timing correction amount for each cylinder depending on the presence or absence of knocking, and the ignition timing calculation unit 8 sets the basic ignition timing ADV. The final ignition timing is set by adding the correction amount to
The ignition timing drive circuit 9 outputs an ignition signal to the corresponding ignition cylinder of the engine, so that ignition is performed at the set ignition timing in the same manner as in the prior art.

Next, detection of knocking will be explained in more detail according to the flowchart shown in FIG.

In step (denoted as S in the figure) (2), based on the signal from the crank angle sensor 21, it is determined whether or not there is an interval 9 in which knocking occurs frequently, for example, a crank angle interval from 10° to 57° after top dead center. This portion corresponds to the knocking occurrence section detection means.

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

When they match, the process proceeds to step 3 where the voltage signal from the knocking sensor 2 is converted into an A/D converter 11.
At the same time, the A/D conversion value of the relevant section is sequentially RA
Store in M. That is, this function and the RAM correspond to signal storage means.

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

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

The functions from step 4 to step 7 correspond to the extreme value storage means.

If it is determined in step 1 that this is a section where the knocking frequency is low, the process proceeds to step 8, where it is determined whether or not the vehicle has just transitioned from a high frequency section to a low frequency section.

If the determination is No, the process proceeds to step 9, and it is determined whether or not the A/D conversion timing coincides with the A/D conversion timing set at a low frequency.

Note that the functions of steps 2 and 3.9 correspond to conversion frequency control means.

When they match, the process proceeds to step 10, where the voltage signal from the knocking sensor 2 is A/D converted by the A/D converter 11, and the A/D converted values of the relevant section are sequentially stored in the RAM.
to be memorized. That is, this function also corresponds to the signal storage means.

Next, the process proceeds to step 11, where the signal data in the relevant section is subjected to weighted average processing.

In step 12, the processed data is stored in the memory BG.
Note on L.

Further, if the determination in step 8 is YES, step 13
Proceed to the maximum value data DMA stored in step 5.
Compare X with the weighted averaged value BGL.

If the former value is greater than the latter value by a set value or more, the process proceeds to step 14, but if not, the process proceeds to step 15, where it is determined that there is no knocking.

Next, in step 14, the minimum value data DMIN stored in step 7 is compared with the weighted average value BGL. If the former value is greater than the latter value by a set value or more, the process proceeds to step 16 and it is determined that there is knocking; otherwise, the process proceeds to step 15 and it is determined that there is no knocking.

Here, the portions from step 11 to step 16 correspond to knocking determination means.

Since the weighted average value BGL outside the knocking generation section is 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 this is sufficiently high, it is determined that the amplitude of the engine vibration is equivalent to that which occurs when knocking occurs, and a determination is made that knocking has occurred. However, for the sake of simplicity, the weighted average value BGL may be compared with a previously known bias voltage without obtaining it, and in this case, A/D conversion is not required at all in a section where knocking frequency is low. That is, the present invention improves the A/
This includes cases in which the frequency of D conversion is 0.

With this configuration, apart from the A/D converter, all signal processing for knocking detection can be performed by software, and the frequency of A/D conversion can be increased only in specific sections where knocking is likely to occur. Therefore, there is enough room to perform calculations for other controls of the internal combustion engine in other sections.
There is no need to provide a dedicated A/D converter with high calculation speed.

Therefore, it is possible to significantly reduce the cost of hardware conventionally required for knocking detection and its adjustment, and also eliminate the need for adjustment.

In this example, by increasing the bias voltage of the knocking sensor, the presence or absence of knocking can be determined by capturing the maximum and minimum values, so high accuracy can be determined. A configuration may also be adopted in which knocking is determined by rectifying the waves and capturing only the maximum or minimum values.

<Effects of the Invention> As explained above, according to the present invention, the hardware for detecting knocking can be greatly simplified, the cost can be significantly reduced, and there is no need to adjust the hardware. It is.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 is a block diagram showing the configuration of the present invention.
FIG. 4 is a diagram showing the configuration of an embodiment of the present invention, a flowchart showing a knocking detection routine of the above embodiment, and FIG.
FIG. 2 is a diagram showing the configuration of a conventional example. l...■ type 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 Patent applicant Fujio Sasashima, agent of Japan Electronics Co., Ltd., patent attorney

Claims (1)

[Scope of Claims] Vibration detecting means for detecting vibrations occurring in an engine and outputting the detected vibrations as a voltage signal; Knocking occurrence section detecting means for detecting a predetermined crank angle section where knocking occurs frequently; and the vibration detecting means. an A/D converter that A/D converts a signal from the vibration detecting means; and an A/D converter that converts the signal from the vibration detecting means into an A/D converter; a conversion frequency control means for greatly controlling the frequency of conversion, a signal storage means for storing the signal converted by the A/D converter, and a conversion frequency control means for storing the signal converted by the A/D converter; extreme value storage means for determining and storing at least one of a maximum value and a minimum value; What is claimed is: 1. A knocking detection device for an internal combustion engine, comprising: knocking determination means for determining the presence or absence of knocking by comparing the /D-converted signal value.