JPS5990019A - Knocking detector for internal combustion engine - Google Patents

Abstract

PURPOSE:To secure processing such as A-D conversion and to improve the ability in knocking detection by detecting a frequency characteristic of the knocking, and deciding on it by a microcomputer and controlling an ignition point. CONSTITUTION:Only a frequency component which is characteristic of the knocking in the detection signal of a knocking detector 1 is extracted by a filter circuit 2. Then, the A-D conversion is performed almost at each peak value of a sine wave and the microcomputer 6 which is equipped with a central processing unit, storage device, input/output device, etc., and generates a timing signal for the start of the A-D conversion according to a signal from a comparing function for the threshold level given to an A-D converter 5 averages the output signal of the A-D converter. Then, a knocking decision level is calculated and a maximum value in a specific period is compared with the knocking decision level to decide whether it is a knocking or not; when the maximum is less than the specific level, the indication of the forcible conversion start is sent to the A-D converter and the decision result is outputted to an ignition point controller.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a knocking detection device for detecting knocking in an internal combustion engine.

As an improvement to the conventional knocking detection device using a °7 analog circuit, the present applicant has previously proposed an invention in which the knocking detection device uses a digital circuit with a convex precision (Japanese Patent Application No. 59424/1982). In the invention proposed earlier, the knocking detection signal is classified into a low-frequency vibration component derived from engine vibration, a high-frequency dynamic component derived from combustion, etc., and a high-frequency vibration component derived from ignition. By passing this detection signal through a filter circuit, low and high frequency components are removed.
Focusing on the fact that it is detected as a sine wave (KHz), the information necessary for a knocking detection device is not the entire knocking waveform, but its peak value, and the peak value of the sine wave is also the necessary information. Taking advantage of the fact that the slope of the neighborhood is constant and gentle compared to the slope of the rising edge and the falling edge, the sine wave knocking detection signal is delayed by a predetermined time from the point when the knocking detection signal crosses a predetermined threshold. -U, near each peak value of the sine wave, Δ
-1] J on which the conversion is performed.

That is, when the program of Δ-1) conversion is started,
The mode of the comparator in the microphone +1 combination is specified, and the threshold level TI+ is set for the 0 level. And start the comparator.
Threshold level Th of the horn kink signal which is a sine wave
After recognizing the rising F from (K+-), we move on to the routine to detect the rising F from (K+-).
1 break is looped with -u' to detect rise -1 and gap, and then a delay time [Delta]1] is set, and the immediate vicinity of the peak 1 is converted to [Delta]-I). However, if the knocking signal becomes so small that it does not reach the threshold level Tt+, such as at low speeds and light loads or when there is an error in the p-sensor, the above logic will not perform the conversion (8-1), and the knocking detection accuracy will decrease. ``Improve your health'' is not a big deal.

Therefore, the present invention makes it possible to forcibly perform 8-1 conversion if the rising edge of the 42-nogging signal is not detected within a predetermined time, thereby preventing processing such as 8-1) conversion from being performed. The purpose of this is to further improve the ability to detect knocking.

Below, a knocking detection device according to the present invention will be explained according to an embodiment. FIG. 2 is a block diagram of an embodiment of the present invention. In Figure 2, 1 is vibration due to engine knocking;
Knocking detector that detects sounds, etc., 2 and 1 knocking l
Out of the detection signal of output device 1, only the frequency component peculiar to knocking is passed through the filter 1 circuit, and 5 converts the detection signal 1d from an analog signal to a digital signal (Δ-1).
It is a variable 1 negative instrument. 6 is a microphone 11 computer,
Central processing unit (CPU), storage W (ROM,
RAM), input/output device (Ilo), etc., and Δ-T
) Eight conversion amount depending on the signal from the comparison function that comes with the converter! +11 timing signal is applied, the output signal (digital signal) of the A-D converter is averaged to calculate the knocking judgment level, and the maximum value of the digital signal within a predetermined period is calculated.

It is determined whether or not there is knocking by comparing with the king determination level, and the °ζ determination result is output to the ignition timing control device based on the ignition signal from the JI control device at the time of ignition shown in the figure.

Next, an example of a detailed circuit diagram of the configuration shown in FIG. 3 is shown. The filter circuit 2 includes a bypass filter circuit consisting of a capacitor 21, a resistor 22, a resistor 23, and a capacitor 924.
The pan 1 pass filter circuit 118 is composed of a low pass filter circuit consisting of the following. The noise detection signal of the non-king detector 1 passes through the soil recess 1182 to remove the noise component and becomes a sine wave with a knocking frequency near frequency 8Ktlz, which is transmitted to the A-D converter 5 and the microphone 11 combination cork 6. It is input to the analog end 7-AN of the built-in 1-chip mark 11:I monitor 61. In this embodiment, an M 88 B 4.1.3 manufactured by Tomi 13M Co., Ltd. is used as a one-depth micro combi coater. The 1f-Nopma microcomputer 61 includes a well-known oscillator 62, a power supply reset circuit 63, and a +1
864 is connected. Also, ignition timing i1a not shown in the figure
The ignition signal (iGt) from the control device is a human resistance 65,
It is connected through an input circuit consisting of a collector resistor 66 and a transistor 67 to an interrupt terminal iRQ of a 1-deep microcomputer. The output from the computer 61 passes through the 1-chip microphone ladder 69.
]- and is supplied to the ignition timing control device by an electric IE current converter 68.

Next, the operation of this embodiment 1-11 will be explained using FIGS. 4 to 7. The m4 diagram shows the knocking detection, 'I'11 constant, and timing signal of the j-kunku-yaku calculation output in this embodiment.
Figure 5 is Feature 1 showing the basic program flow. Starting step 220
In the main routine starting from , the built-in timer calculates the ignition period 1' l 80 i1 (step 221). Based on that I, the delay time (masking time) until the start of conversion (Δ-L) 'I' 1, 8- 1) Time to perform the negative change (judgment time) 'r2, 8-1) 5 & Multiplication factor CK value for multiplying the average value of the knocking detection signal to obtain the judgment level to be compared with the conversion value), the average value Add a predetermined value (i.e., judge / \ average value x l (value 4 - n
(step 222).

1 When ignition is input to iRQ, which is the interrupt input terminal of Combibutaro 1! ! II 1lil
The ignition signal '1 (iGt) from the control device is input to the transistor 67 (210 in FIG. 4), and the microphone 1. l twot
Since input signal is input to input processor 61, the falling signal (FF14, Figure 221) causes an interrupt to the microphone [1 computer, - evening (F65, Figure 211-1) o After starting the interrupt routine, interrupt processing ( During the masking time Tl (FIG. 4, 213), the microphone 11 computer has an A-1) conversion (FIG. 5, 213-1).

After the masking time is over, the above-mentioned Δ-1] change is repeated based on the value of time 'F2 (FIG. 4, 214) (ffi5, FIG. 214-1, 214-2). After the conversion is completed, A-1) The maximum value and average value of the converted values are calculated in Figure 4.21.
As mentioned above, the judgment value is calculated at the timing of step 5, and the offset value is calculated using the offset value (Fig. 5, 215-1
．． 215-2), and its value is further compared with the maximum value among the 8-I) transformations (NS5 diagram 215-3).

The judgment result is that the 8-person boat of the microcomputer is connected to the 41st PJ 216 terminal I min 7”r output sale (i
s5r212 ] 6-1) It is also converted one by one by passing through a resistance ladder, and its analog value is converted into a current by a voltage-current converter and output to an ignition timing control unit device (not shown). The judgment output is expressed as a retard amount.

Next, an outline of each control step in this embodiment will be explained. trout,
1-Conversion time 'I''l, 8-1) Conversion judgment time'■゛2
is a value proportional to the period I'1180 (masking time'■
1 is, for example, l m s to 2.51 TIS, and the determination time is, for example, 2 m s to 5 m s). A-1
) The average value of the converted values is averaged by rough 1 wear. There are 3 levels of judgment, the 1st level is (average value) x (1 (value) - (offseno L value), the r62 level is (1st level) x 2.13 level is (ffil level is 3 at level 3)
Two knocking determinations are made, and the determined results (strength) are output as a retard amount to the ignition timing control device (not shown). In this example, the ignition timing retard width is 0 to 16° CA (
crank angle).

Next, the main part of the present invention, il of the △-1] conversion part
'P Detailed explanation of operation in 6 lines using Figures 6 and 7).

301 in FIG. 6 corresponds to one period of the detection signal.

As mentioned above, the detection signal is an 8 KHz sine wave. A-L) Unusual catch 11g starts (step 32)
0), the mode of the 21 amparator, which is the comparison function in the 1-chip microphone 11:1 nviewer, is specified.
A threshold F level Th is set for the level (step 321). Then, the inverter is started (step 322), and the falling time 'l''Do of the sine wave 301 from 1'11 is detected in step 323-.
1), M'! Further check the TI+ level to prevent activation (step 323-2).

After detecting the 1'h level, the routine moves to detect the rise from the Th level (step 325), and the delay from the rising detection time TZl by a predetermined time ΔI] U (step 32G>, time 'l ``S1 is reached.In addition, in the rising edge detection routine (step 325), 1 judgment is arranged in series, and if a rising edge is not detected (but eventually in step 32
Let's move on to 6.), so that the calculation process does not fall into an infinite loop. Then, from time 'T' S L to A-1) conversion is started at peak 3 of the sine wave 301.
It is set around 10-1. At that time, the sine wave 30
The peak of 1 is considered to be almost constant compared to the slope of the rising edge of the sine wave, and the slope of the falling edge of the sine wave.
The peak value VP of 01 is (). I'll lr) Irregular start time 'rsl! '4 Obtained value VS L end time 1' F 1 - Cji The obtained value VFI is extremely small in difference compared to the peak value VP, and furthermore, in this example, A-1) conversion is a successive approximation method. Since the Δ-1) conversion is used, the obtained eight-way conversion values are VS], VF], l-
This is close to ρ. The resulting conversion value is read and placed in memory (step 32B) and the next operational step 329 is entered.

Next, other embodiments of the present invention will be shown. This embodiment will be explained according to FIG. The detection signal obtained by passing through the knocking detector 1 and the filter circuit 1132 by 1JJl is sent to the Δ-D converter 5.
And, the register 1 level] is manually input to the micro combi coater 6 at 2 through an amplifier 7 which determines whether the beam is erect - 1 or 1. The detection signal (,1) is input to the interrupt terminal r- of the microcomputer, and the interrupt is synchronized to +'r-1-re or falling from the threshold level TI+ of the detection signal.In that case, Compared to the software-based 21 amparator in the previous embodiment, this embodiment improves the response speed by using a hardware interrupt terminal.After synchronization is detected, the Δ-D converter 5 is output from the microcomputer 6.・Send \ star 1 signal Δ
-1] Start conversion. As shown in FIG. 9, the falling point τ■ of the 1 Imade signal to the I'h level
] is detected.

Thereafter, the microphone +, 11-ampputer 6 detects Δ-■] conversion time τ[]. After that, the Ma-Iku II combination Gotaro predicts the Δ-D conversion point τZ and passes through Δ-I]
The conversion is performed using the speed of the converter, the frequency of the detected waveform, and ζ
, its starting point can be made variable, thereby making it possible to obtain a peak (111110) of the detection signal.

8-1) The present invention starts conversion after a predetermined time delay from the point in time when a knocking detection signal having a frequency specific to knocking crosses a predetermined level. lt
; Δ−■] conversion is performed near each peak value of the s/u1 sine wave, and further Δ−I) conversion is performed.
llJ] If the knocking detection signal does not reach the predetermined threshold within a predetermined period of time, Δ
-1) Weird 1! ! ! The amount of conversion of the knocking signal into a digital value! 'ti is specified as 4), ・), and the knocking state is determined from these 8-1) converted values, making it easy to convert each peak value of the knocking detection signal into a digital signal. Therefore, accurate knocking can be detected, and if the knocking detection signal is very small, processing such as Δ-I) conversion will not be necessary (and the peak bold circuit vr is unnecessary). This has the excellent effect of simplifying the configuration.

[Brief explanation of drawings]

FIG. 1 is a main flowchart 1 showing the processing procedure of Δ-1 conversion related to the present invention, FIG. 2 is an overall configuration diagram showing an embodiment of the present invention, and FIG. dIII block diagram, FIG. 4 is a timing chart schematically showing the timing of processing in the apparatus shown in FIG. 2, and FIGS. 5 and 7 are
The figure is a flowchart showing the processing procedure for the computer shown in FIG.
〇 A diagram showing the timing of conversion, FIG. 8 is an overall configuration diagram without showing other embodiments of the present invention, and FIG. 9 is a diagram showing the timing of /l-D conversion in the apparatus shown in FIG. 8. be. ■ Knocking detector, 2 Filter circuit, 5
...Δ-D converter, 6...Micro combi coater. Representative Patent Attorney Takashi Okabe 132 Figure 1 Figure 2 Figure 6 Figure 8

Claims (1)

[Claims] a knocking detector for detecting knocking in the internal combustion; and a knocking detection signal having a frequency specific to horn kink detected by the knocking detector, which digitally converts the knocking detection signal with a predetermined time delay from the point in time when the knocking detection signal has a frequency specific to the horn kink and crosses a predetermined level. an A-D converter for converting the knocking detection signal into a digital value; and a microcomputer for determining the 4L state of the
n; 1 within a predetermined time during the conversion period.
If the knocking detection signal does not reach the predetermined value in 111, the microcombi go to the
A knocking detection device for an internal combustion engine characterized by instructing a D converter to start converting a knocking detection signal into a digital value.