JPS60183529A - Detector for knock - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a knock sensor for detecting engine vibration;
The present invention relates to a knock detection device comprising a knock filter that can pass in the frequency band of at least one expected knock signal, and a comparator connected to the knock filter at one input side.

BACKGROUND OF THE INVENTION A method and a device for detecting an engine knock are already known from DE 32 15 683 A1. With this installation, the vibration of the engine was measured 1. flj
It has a knock sensor that converts the determined vibration into a corresponding electric signal, a knock filter whose frequency band of this electric signal is a pass band, and a knock detection device 1 that converts the measured knock phenomenon into an effective measurement value. A comparator is provided which sends a signal to the output side when it is identified as such.

Problems to be Solved by the Invention Conventional devices have problems in that the suppression of background noise is uneven, especially at low rotational speeds, and that the dynamic characteristics are poor at relatively high rotational speeds. There is. This is because a bank ground noise component is inevitably included in the engine knock signal on the input side of the comparator due to the bandpass filter and rectifier. On the other hand, the background signal supplied to the other input side of the comparator includes a signal integrated by the second smoothing circuit and delayed with respect to the knock signal, and this is This causes insufficient dynamic characteristics as described in -1-.

According to the present invention, in the knock detection device π of the type mentioned at the beginning, the knock filter is connected to the 7-trick sensor, and the input end is connected to the knock sensor, and the comparison This problem is solved by providing a rectifier with the output 1i111 connected to the other input side of the device.

Embodiment In the embodiment of the present invention shown in FIG. (The output 111j &:I'- of the knock filter 4 is connected to the non-inverting input side of the ratio I interrupter 5, and the inverting input side is connected to the rectifier 9. The output side of the comparator 5 is connected to the background noise terminal 10.The output side of the comparator 5 is connected to a retriggerable monostable multivibrator 7 via a knock signal terminal 6. 7 output Qt
jl k1 Connected to the input side of the microcomputer 8. The output side of the microcomputer 8 is the test line 12
It is connected to the test signal terminal 3 via. An error reporting stage 13 is connected to the ground noise terminal 10, and the error reporting stage itself is connected to the microcomputer 8 via a reporting line 14', t.

The device 1 evaluates the output of the Tsukusen M1 which was missed in the engine block and sends out a logic signal when knock occurs during combustion to the signal terminal -r.6vc. For this purpose, an output signal containing a background noise component and a knock noise component at the same time is transmitted to a knock filter 4 tuned to the mechanical resonance frequency of the engine during combustion.
According to 11.4. wave. The knock filter 4 has a fixed amplification degree. In addition, the output signal of the knock sensor 1 is also supplied to the rectifier 9. The rectification obtained by this (J is the level of the inverting input side of the comparator 5, and is shifted in the positive direction depending on the sensor output voltage amplitude.The ratio I section 5 applies a certain reset characteristic to its output signal. The knock filter 4 has a small input off point 1 to obtain 1. Due to the hysteresis characteristic, the background noise signal of the knock filter 4 is suppressed.In other words, the comparator 5 forms an amplitude filter L2,
The passage area depends on the amplitude of the output signal of the knock sensor 1.

The level shift due to the background noise rectification value on the inverting input side of the ratio I component 5 is caused by temporal changes in engine noise such as changes in bearing play or valve play, and by the product '7) of sensor 1. The function is to automatically adapt the response sensitivity of foil manufacturing to fluctuations in the output signal amplitude of the knock sensor 1 that inevitably occur due to aging or the like. The level shift is then carried out in parallel in such a way that the change in the background noise at the output of the knock filter 4 counteracts the proportional level shift at the input of the comparator 5. As a result, background noise is suppressed as much as necessary so as not to lower the response sensitivity more than necessary. By correspondingly adjusting the amplification degree of the knock filter 4, an optimum condition between detection accuracy and error probability can be found.

Therefore, a pulse-like signal is applied to the knock signal terminal 6 during knock combustion, and this signal triggers the retriggerable monostable multivib break 7.

The time constant of the multivibrator 7 is selected in such a way that at least the lowest passing frequency of the knock filter 4 keeps this multivibrator active. Therefore, the output signal of the multi-pipe rake 7, ie the pulse width, is a suitable measure of the duration of the knocking process or the strength of the knocking. This signal is processed by the microcomputer 8 (4
``! is issued and the duration is totaled.The microcomputer 8 can of course be directly connected to a comparator 5vC, and the hardware or software can judge whether or not the measured non〃 is valid. 1
You can also sing. Via one interrupt input, the pulse length or the number of oscillation sequences of the output signal of the comparator 5 is then 3
1 and compared with a predetermined threshold. At this time, the microcomputer 8 serves as a part of the vehicle's computer, and this computer performs functions of each engine 11 that are modified for engine operation, such as knock control related to changes in ignition timing. This embodiment is not shown in the figure for the sake of simplicity.

The microcomputer 8 is connected to the test signal terminal 3 via a test line 12, and every 100 combustions a cyclic v
Send one test signal to test signal terminal 3vc. Based on this, when the microcomputer 8 detects one pulse of the multiplier 7, the knock detection function of the device is checked. In the case of inspection in a factory, a predetermined type of signal may be applied to the test signal terminal 3 to inspect the frequency characteristics, sensitivity, etc. of the device.

Error notification stage 1 from background noise terminal 10
3 takes out the output signal of the rectifier 9. The error reporting stage detects a failure of the knock sensor or a disconnection of the sensor cable by the absence of a 10vC bank ground noise at the background noise terminal. In case of failure,
The error notification stage 13 emits an optical or acoustic signal to the driver and sends the notification via the 1rII signal line 14 to the vehicle's computer (C
tell. In response to this, knock control is interrupted for a total of nine engines, and the internal combustion engine is adjusted to an operating state that is not dangerous in any case by adjusting the ignition lυJ delay. The technical aspects of such an error reporting stage, such as the smoothing of background noise at the input of a threshold switch, are well known to those skilled in the art and are therefore not shown in FIG. j for the sake of brevity.

The embodiment of FIG. 2 has largely the same construction as the embodiment of FIG. 1, and these are designated by the same symbols. The wooden difference lies in that a filter 11 is connected between the input Mj element 2 and the input end of the rectifier 9. This filter 11 is tuned to the frequency band of bank ground noise.

The increase in resonance no longer interferes with the amplitude filtering action of the comparator 5.

The knock detection device for an internal combustion engine of the present invention can be used for both an external ignition type internal combustion engine and a self-ignition type internal combustion engine. According to a particularly advantageous embodiment of the invention, the actual value of the knock control acts, for example, on the ignition timing or the injection time F, or on the intake pressure of the intake air of the internal combustion engine. It is preferable to combine the device of the invention into one casing and install it together with the knock sensor 1 on the engine.In this case, the knock signal can be transmitted through one line to many automatic sensors.
[Not used in 1F] It is supplied to the 5 transistor ignition device to adjust the 1JIJ delay at the time of ignition.

Effects of the Invention The knock detection device of the present invention has an advantage over the prior art in that it does not integrate the output signal of the knock sensor. 6, which results in significantly better background noise suppression, especially at low engine speeds.A further advantage is that the production costs are lower than before. The device of the invention can be easily integrated.

In an uninvented embodiment, the hysteresis characteristic of the comparator is
It affects the output circular wave number of the knock filter and suppresses the bank ground noise signal. If the offset of the comparator is
There is an advantage that this offset can be used to achieve a constant recency characteristic of the comparator output signal.

By tuning the filter to a passband above the engine's resonant frequency, sudden, resonance-induced rises in the bank ground noise signal no longer interfere with the detected VC. The filter can be constructed very simply with one short circuit or buffer amplifier. The test signal terminal makes it extremely easy to test the knock detection function in the factory.
Alternatively, the knock detection function can be monitored during engine operation by periodically generating a test signal by the vehicle's computer. A retriggerable monostable multi-bibreak at the output of the comparator generates a pulse as an output signal that can be directly applied to processing by a microcomputer, the duration of which is a good measure of the strength of the knock. Become. The error reporting stage connected to the background noise terminal a has the advantage of easily monitoring the knock sensor or its lead wire. If no pressure is applied to the background noise terminal, send an error notification stage or optical signal or an audible signal to the driver of the vehicle, and apply a signal to the vehicle's A1 calculator. In response, the computer interrupts knock control and shifts the ignition timing to a safe value.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a first embodiment of a knock detection device comprising a trigger stage and a microcomputer, and FIG. FIG. 2 is a block circuit diagram of an embodiment. 1. Knock sensor, 3. Test signal qz'-34.
...Knock filter, 5...Comparator, 7...14i
Stabilizer/'Chiba brake, 9... rectifier, 10...
・Bank ground noise 'I: Ia child, 11... Filter, 13... Error notification stage 1st page continuation @ Inventor Beter Ruth・Ter Kej, Buchsl-24 Schwieherteingen, Federal Republic of Germany, 7 Lesslauer Strasse 5I

Claims (1)

[Claims] 16. A knock sensor (1) that detects engine vibration, a knock filter (4-) capable of passing 1 m in the frequency band of at least one expected knock signal, and the knock filter (4). c Comparator with one input connected (
5), the knock filter (4) is connected to the knock sensor (1), the knock sensor (1) is connected to the vc input side, and the ratio gear (5) is connected to the knock sensor (1).
) whose output side is connected to the other input end of the rectifier (9)
A knock detection device, characterized in that it is provided with a. 2. The knock detection device according to claim 1, wherein the comparator (5) has a hysteresis characteristic. The knock detection device according to claim 1 or 2, wherein the comparator (5) has an offset. 4 A filter (11) is connected between the knock sensor (1) and the rectifier PFi (9).
The knock detection device according to any one of the first to sixth peaks of the range of j. 5. The knock detection device according to claim 4, wherein the filter (11) is tuned to the bank ground noise of the engine. 6. The test signal terminal (3) is connected to the knock filter (4). The knock detection device according to any one of claims 1 to 5, wherein the test signal is supplied to the knock detection device via the terminal. 7. The test signal is supplied via the test line (12). 81. The knock detection device according to claim 6, wherein the signal is supplied to the knock detection device, and the failure or function of the knock detection device is checked from the response of the differential comparator (5) to this signal. (5) The output side of the trigger stage (7) is connected to the trigger stage (7). ) is a retriggerable but stable circuit, and the time constant of the trigger stage (7) is selected in such a way that the trigger stage is kept activated by the lowest cutoff frequency of the knock filter (4). The knock detection device according to claim 8. 10 The output (flu K bank ground noise terminal (10) of the rectifier (9) is connected, and the background noise terminal (10) +c error notification stage (13)
is connected, and the error im 8 stage (13) indicates that if the level of the bank ground noise terminal (10) falls below a predetermined level, the knock sensor (1) will fail and/or the lead of the knock sensor (,1) will occur. A knock detection device 6゜11 according to any one of claims 1 to 9, which generates at least one notification that a fault has occurred in the line, generates a pulse from the output signal of the comparator (5). The claimed invention is provided with a device for determining whether a measured knock can be detected as a valid value by summing the length or the number of a series of oscillations of the output signal and comparing it with a predetermined threshold value. The knock detection device according to scope 10.