JPH01209326A - Knocking detecting device for internal combustion engine - Google Patents

Abstract

PURPOSE:To detect the generation of knockings correctly by a simple device, by counting the frequency by which knockings detected by a sensor exceed the judging level, updating said judging level and comparing said updated level with knocking signals, thereby judging knockings. CONSTITUTION:A knocking sensor M1 detects the generation of knockings caused in an internal combustion engine, and outputs a signal to a judging level generating means M2. The generating means M2 counts the frequency by which the level of the knockings exceeds the incorporated judging level, updating the judging level and inputting the updated level to a comparing means M3. The comparing means M3 inputs the frequency of the knockings exceeding the updated level to a knocking judging means M4 to judge the knockings. Accordingly, knocking can be correctly judged by a simple circuit structure of the use of a microcomputer with its capacity reduced.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a knock detection device for an internal combustion engine that detects knocking occurring in the engine.

[Conventional Technique #F1] Conventionally, as a method for detecting knocking that occurs in an internal combustion engine, Japanese Patent Application Laid-Open No. 60-190832 discloses a method for determining the next cycle's noise level and knock determination by counting pulses in which the knocking signal exceeds the noise level. The level is updated in a time-division manner, knocking is determined according to the count of pulses in which the knock signal exceeds the knock determination level, and ignition timing retardation control of the internal combustion engine is performed. However, although microcomputers are used to create and update the knock detection level and to judge knocks based on the count of pulses exceeding the noise level, these calculations require a large amount of capacity and require the use of multiple people. The need for an output boat required an expensive microcomputer.

Therefore, the knocking signal and the knocking detection level are compared with a comparator, and the knocking detection level is updated to the median value of the knocking detection signal according to the result of counting the pulses, and the knocking is determined. Moreover, the device eliminates the need to set the magnification required to create knock judgment levels (
JP-A-62-7975) has been proposed.

[Problems to be solved by the invention] However, in such conventional devices, the problem as shown in Fig. 3 (b)
When a knocking signal e shown in Figure 3 (b) shows a noise with a waveform that does not have a very high peak value but has a long duration, the knock determination level d shown in Figure 3 (b) indicates that there is no knock. Figure 3 shows the knocking signal e that was determined to be knocking and exceeded the bell d even though no knocking had occurred.
It is output as the pulse signal i shown in (d). When the signal k shown in FIG. 3 (E) that is obtained by counting the pulse signals i exceeds a predetermined count value, the knock occurrence signal 1 shown in FIG. Therefore, there is a problem in that the ignition timing control of the internal combustion engine may result in a decrease in output due to incorrect timing retardation.

Therefore, the present invention aims to solve the above problems,
It is an object of the present invention to provide a knock detection device for an internal combustion engine which has a simple configuration and does not make an erroneous determination.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration as a means for solving the problems. That is, as illustrated in FIG. 1, there is a knock sensor M1 that detects knocking that occurs in an internal combustion engine, and a frequency at which the knocking signal detected by the knocking sensor M1 exceeds a knock determination level determined based on the knocking signal. a knocking signal detected by the knock sensor M1 and a knocking signal detected by the knock sensor M1; Comparing means M3 that compares the knocking signal with the knocking determination level obtained by M2 and outputting a knocking signal that exceeds the knocking determination level; and determining knocking based on the counting result of the knocking signal that exceeds the knocking determination level by the comparing means M3. This is the structure of a knock detection device for an internal combustion engine, which is characterized in that:

Further, the determination level generating means M2 includes a knock sensor M
After the knocking signal detected by No. 1 is amplified, the frequency of exceeding a knock determination level determined based on the amplified knocking signal is counted, and the knock determination level is updated according to the counting result.

Further, the determination level generating means M2 may be configured to update the knock determination level and then digitally increment and output the updated knock determination level.

[Operations] In the knock detection device for an internal combustion engine having the above configuration, the knock sensor M1 detects knocking occurring in the internal combustion engine, and the determination level generating means M2 detects the knocking signal detected by the knocking sensor M1. Counting the frequency of exceeding the knock determination level determined based on the signal, and updating the knock determination level according to the counting result,
Outputs the amplified knock judgment level and compares it to EFi M
3 compares the knock signal detected by the knock sensor M1 with the knock determination level by the determination level generating means M2, and outputs a knocking signal exceeding the knock determination level, and the knock determination means M4 compares the knock signal detected by the determination level generating means M2. A knock is determined based on the counting result of knocking signals exceeding a knock determination level.

Therefore, accurate knock determination can be performed with a simple configuration.

[Example code] Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 2 is a block diagram of a knock detection device for an internal combustion engine, which is an embodiment of the present invention.

Reference numeral 1 is a knock sensor that uses a piezoelectric element to detect finger movements caused by internal combustion engine knocking. A filter 2 that passes only a frequency component (for example, 8ktlZ) is manually inputted. This filter 2
The output signal is input to an amplifier 4 that amplifies the knocking signal that has passed through the filter 2 by a predetermined amplification factor (in this embodiment, twice). In addition, by comparing the knocking signal amplified by the amplifier 4 with a knock judgment level, which will be described later, and which is input from the D/A converter 6,
A comparator 8 is provided that outputs a pulse signal every time the knocking signal exceeds a knock determination level. The output signal from the comparator 8 is input to a counter 10 that counts the pulse signal output from the comparator 8 over a predetermined period of time. This counter 10 can detect engine firing without being affected by ignition noise, etc., based on the ignition timing signal IGt (signal a shown in FIG. 3 (a)) calculated by ignition timing control. A masking signal generation circuit 12 that outputs a determination interval signal as shown in FIG. The pulse signal is counted based on the determination interval signal output from the pulse signal, and a count value C is output.

The output signal of this counter 10 is manually inputted to an up/down controller 14 which outputs a signal for updating the "C knock determination level" according to the counted value C. This up/down controller 14 determines, for example, when the count value C is C=0 based on the count result of the counter 10, -
XmV, when the count value C is C=1, OmV, the count value C
When C=2 to 14, +Yrr+V, and the count value C is C
When ≧15, an 8-bit digital update signal corresponding to +ZmV is output. The update signal from the up-down controller 14 is manually input to the knock judgment level register 16, and the knock judgment level register 16 is updated to the previous knock stored in the knock judgment level register 16 based on the update signal from the up-down controller 14. Update the judgment level. The updated knock determination level in the knock determination level register 16 is output as a knock determination level converted into an analog signal by the D/A converter 6 formed from a resistance ladder.

The amplifier 4, D/A converter 6, comparator 8, counter 10, up/down controller 14, and knock judgment level register 16 function as judgment level generating means.

On the other hand, the knocking signal e that has passed through the filter 2 is manually inputted and compared with the knocking judgment level from the D/A converter 6, and a pulse signal is output every time the knocking signal exceeds the knocking judgment level. A comparator 18 is provided as a comparator. This comparator 1
8 is the pulse signal output from the comparator 18,
It is connected to a counter 20 that counts pulse signals during this predetermined time based on the determination interval signal outputted from the masking signal generation circuit 12. The output signal from this counter 20 is input to a knock determination circuit 22, and the knock determination circuit 22 outputs a knock determination signal when the counted value 02 by the counter 20 becomes a predetermined value or more. This knock determination circuit 22 is connected to a synthesizer 24 that synthesizes and outputs human power signals. This synthesizer 24
Furthermore, there is a fail judgment for making a fail judgment when an abnormality occurs in the knock sensor 1, filter 2, amplifier 4, comparator 8, counter 10, etc. and an abnormal signal is output based on the signal from the up-down controller 14. A circuit 26 is connected. The synthesizer 24 synthesizes the output signals of the knock determination circuit 22 and the fail determination circuit 26 and outputs the combined signals to a microcomputer that controls knock control factors (ignition timing, air-fuel ratio, supercharging pressure, etc.) (not shown).

Note that the counter 20 and the knock determination circuit 22 function as knock determination means.

Next, the operation of the internal combustion engine knock detection device of this embodiment will be explained.

When the internal combustion engine is operated, vibrations and the like are detected by the knock sensor 1, filtered by the filter 2, and inputted to the amplifier 4 and the comparator 18 as a knocking signal e as shown in FIG. 3(b). The amplifier 4 amplifies this knocking signal e with a predetermined amplification factor to obtain the knocking signal e as shown in FIG.
The amplified knocking signal g shown in is output to the comparator 8.

The comparator 8 compares this amplified knocking signal g with a knocking determination level C manually inputted from the D/A converter 6, and outputs a knocking signal g that exceeds the knocking determination level C.
is output to the counter 10 as a pulse signal l as shown in FIG. 3(d). The counter 10 counts this pulse signal i during the judgment period of the judgment period signal S as shown in FIG. Output. The up-down controller 14 is based on this count value C, and for example, when the count value C is C=0, -Xm
V, when the count value C is C=1, OmV, when the count value C is C
When C=2 to 14, an 8-bit digital update signal corresponding to +YmV is output to the knock determination level register 16, and when the count value C is C≧15, an 8-bit digital update signal corresponding to +ZmV is output to the knock determination level register 16.

The knock determination level register 16 calculates based on the digital update signal, updates the previous knock determination level, and outputs it to the D/A converter 6. The D/A converter 6 converts the updated contents into an analog signal, determines a knock, and outputs a bell C to the comparator 8. That is, after amplifying the knocking signal e, a knock judgment is made based on the amplified knocking signal g to determine a bell C, and this knock judgment bell C is updated by feedback control and compared by a comparator 8.

On the other hand, the D/A converter 6 also outputs the updated knock determination bell C to the comparator 18. Comparator 18
As shown in Figure 3 (b) and (d), the filter 2
The knocking signal e filtered by is compared with the knock determination level C, and the knocking signal e that exceeds the knock determination level C is outputted to the counter 20 as a pulse signal. The counter 20 counts the pulse signals during the determination period of the determination period signal outputted from the masking signal generation circuit 12 as shown in FIG. When the count result exceeds a predetermined value, the knock determination circuit 22 determines that a knock has occurred and outputs a knock occurrence signal 1 to the synthesizer 24.

On the other hand, the fail determination circuit 26 performs fail determination based on the signal from the up-down controller 14 and outputs a fail determination signal to the synthesizer 24.

The synthesizer 24 synthesizes the knock occurrence signal and the fail determination signal and outputs the synthesized signal to the microcomputer. The microcomputer detects knock sensor 1 based on the fail judgment.
When it is determined that there is no abnormality and a knock occurrence signal is manually input, control such as retarding the ignition timing is performed in ignition timing control, air-fuel ratio control, supercharging pressure control, etc.

As described above, in the internal combustion engine knock detection device of this embodiment, the knock sensor 1 detects knocking occurring in the internal combustion engine, the amplifier 4 amplifies the knocking signal g, and the comparator 8 and the counter 10 detect the knocking signal g. The frequency of knock determination determined based on the above value is counted, and the knock determination level C is determined according to the counted value by the up-down controller 14 and the knock determination level register 16.
and update the amplified knock detection level C to D/
It is converted by the A converter 6 and output. Comparator 18
compares the knocking signal e with the knock judgment level C and outputs the knocking signal e that exceeds the knock judgment level C, and the counter 20 counts the knocking signal e that has been judged as a knock and exceeds the knock judgment level C. A determination circuit 22 determines knocking based on the counting results.

Therefore, according to the knock detection device for an internal combustion engine of this embodiment, knock determination can be performed with a simple configuration without exchanging signals with a microcomputer, and even when noise with a long-duration waveform occurs, However, since the knock determination level C is set to a high level, only the knock signal is accurately detected without detecting noise. Furthermore, since the microcomputer only needs to control the knock control factor based on the knock judgment signal l, the capacity of the microcomputer is minimized, and the human output is also minimized, so it is possible to use an inexpensive microcomputer or D It can be constructed using only a small number of digital means such as /A converters.

Next, regarding other embodiments different from the embodiments described above,
This will be explained with reference to FIG. Components that are the same as those in the embodiment shown in FIG. 2 will be denoted by the same reference numerals and detailed explanations will be omitted.

The output signal of the filter 2 is input to one side of the comparator 8. Further, the knock determination level C in the knock determination level register 16 is shifted by one bit and the knock determination level C is digitally carried forward, and the knock determination level C is manually inputted to the D/A converter 28. The D/A converter 28 converts this knock determination level into an analog signal and outputs it to the 'C comparator 18.

Therefore, the knocking signal e filtered by filter 2
is input directly to the comparator 8, and the comparator 8 compares this knocking signal e with the knock determination bell d from the D/A converter 6. Further, the knock determination level register 16 outputs a knock determination bell d to the D/A converter 6, and also outputs the knock determination level d.
Knock judgment level C, which is doubled, is manually applied to the D/A converter on the second day. In this way, instead of amplifying the knocking signal e, it is possible to perform the same operation by determining a knock and amplifying the bell d.

Therefore, according to this embodiment, although there is no degree of freedom such as setting the magnification by the amplifier 4 as in the above-mentioned embodiment, it is possible to create a highly accurate knock judgment bell C with no tolerances with a simple configuration.

Although the embodiments of the present invention have been described above, the present invention is not equally limited to these embodiments, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

As described above in detail, the knock detection device for an internal combustion engine of the present invention has the advantage of being able to detect knock with a simple configuration and to make accurate knock determination. Furthermore, the capacity of the microcomputer that controls the knock control factors is minimized, and the human output board is also minimized, so cheap microcomputers and digital
It also has the advantage that it can be constructed using only a small number of digital means such as A converters.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a knock detection device for an internal combustion engine illustrating the basic configuration of the present invention, FIG. 2 is a block diagram of a knock detection device for an internal combustion engine according to the present embodiment, Ml...knock sensor M2... - Judgment level generation means M3... Comparison means M4... Knock judgment means 1... Knock sensor 4... Amplifier 6.28
...D/A converter 8.1 day...Comparator 10.20...Counter 14...Up/down controller 16...Knock judgment level register

Claims (1)

[Scope of Claims] 1. A knock sensor that detects knocking occurring in an internal combustion engine, and a method for counting the frequency with which a knocking signal detected by the knocking sensor exceeds a knock determination level determined based on the knocking signal; a determination level generating means that updates the knock determination level according to the result and outputs the amplified knock determination level; and a comparison between the knocking signal detected by the knock sensor and the knock determination level generated by the determination level generating means. and a comparison means for outputting a knocking signal exceeding the knock determination level; and a knock determination means for determining a knock based on the counting result of the knocking signal exceeding the knock determination level by the comparison means. A knock detection device for an internal combustion engine, characterized by: 2. The determination level generating means amplifies the knocking signal detected by the knock sensor, then counts the frequency of exceeding a knock determination level determined based on the amplified knocking signal, and adjusts the knock determination level according to the counting result. A knock detection device for an internal combustion engine according to claim 1, characterized in that the knock detection device for an internal combustion engine is updated. 3. The knock for an internal combustion engine according to claim 1, wherein the determination level generating means updates the knock determination level and then digitally increments the updated knock determination level and outputs the same. Detection device.