JPH0621844B2 - Engine noise detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention determines whether or not an abnormal noise is generated in the final operation adjusting process of an automobile engine that has been assembled, for example. The device used for the determination, specifically, the detection signal from the detector that detects the operating noise of the engine is separated into signals in a predetermined frequency band, and the presence or absence of abnormal noise is determined based on each separated signal. Related to the device.

(Prior Art) Conventionally, an apparatus of this type is disclosed in, for example, Japanese Patent Application Laid-Open No. 57-196118, which will be described with reference to FIG.

In the figure, reference numeral 1 denotes, for example, an automobile engine for which the above-mentioned assembly has been completed.
It is fixed to the test bench as it is attached to the etc., and the rotation speed detector 2 and other detectors and instruments necessary for the operation inspection are attached here.

Reference numeral 4 denotes an operation sound detector such as a microphone mounted on a crankcase of the engine for detecting an operation sound of the engine 1, a vibration pick-up, and the like, and 5 an operation sound detector 4
Is a charge amplifier for amplifying the detection signal from the charge amplifier 5. When the engine 1 is operated, the charge amplifier 5 outputs signals including various frequency components corresponding to so-called engine rotation noise. 6 is a frequency analyzer, and this frequency analyzer 6 is, for example, 250Hz, 500H
Bandpass filters 6a and 6 with 1 octave configuration having center frequencies of z, 1KHz, 2KHz, 4KHz and 8KHz, respectively.
It is composed of b, 6c, 6d, 6e, and 6f, and the detection signal from the detector 4 via the charge amplifier 5 is input to each of the band pass filters 6a to 6f.
Reference numerals 7a to 7f are averaging circuits for averaging the signal waveforms of the respective frequency bands output from the band pass filters 6a to 6f of the frequency analyzer 6, and converting the signal waveforms into DC voltage levels, and 8a to 8f are meter relays. A DC threshold voltage corresponding to an abnormal signal level in each frequency band is set in each of the meter relays 8a to 8f. When each voltage level output from each averaging circuit 7a to 7f is less than or equal to the threshold voltage set in each meter relay 8a to 8f, the normal lamp of each display 9a to 9f lights up, while each of the above averages When the voltage levels from the digitization circuits 7a to 7f exceed the threshold voltages, the indicators 9a to 9f are displayed.
The abnormal lamp is turned on.

In the above-described machine operation sound determination device, when the engine 1 is making an abnormal noise, the voltage level obtained by averaging the signal waveforms in the band including each frequency component forming the abnormal noise is high. Therefore, the abnormal lamp of the display for the signal that has passed through the band pass filter of the frequency band is turned on. Therefore, by checking the lighting lamp of this indicator, it is possible to judge whether or not the engine 1 has an abnormal noise, and to judge whether or not the engine concerned.

(Problem) By the way, the discrimination device as described above is merely an inspection device for discriminating the presence / absence of the occurrence of abnormal noise and providing it for the judgment of the engine concerned, and therefore, the investigation of the troubles to be performed subsequently,
It did not provide any judgment material for the repair process.

That is, in the above investigation and rework process, in order to narrow down the generation source of the abnormal noise, whether the abnormal noise is continuous or intermittent, and if it is an intermittent abnormal noise, what is its generation period?
The starting point is to investigate the types of these abnormal sounds. As described above, the operating sound is separated into signals in a predetermined frequency band by the frequency analyzer 6, and then the separated signals are simply averaged to obtain the average level. If the generation of abnormal noise is determined based on the above, it may not be possible to determine the abnormal noise that occurs intermittently. This is because in the case of intermittent abnormal noise, the signal level in the frequency band that includes the frequency components that make up the abnormal noise becomes intermittently prominent, but when such a signal waveform is averaged, This is because the averaging level does not always become higher (than the threshold level).

Therefore, an object of the present invention is to make it possible to discriminate the presence or absence of an abnormal sound and the type of the abnormal sound.

(Means of the Present Invention) In a device that separates a signal obtained by detecting an operating noise of an engine into signals in a predetermined frequency band and determines the presence or absence of abnormal noise based on each separated signal, Rotation speed detecting means for detecting (2)
An average value detecting means (12c) for averaging the signals in the predetermined frequency band rectified after separation every predetermined time to obtain an instantaneous signal voltage; and an average value of the signal voltage averaged every predetermined time. A peak value detecting means (14c) for detecting a high voltage value protruding from the signal waveform to be formed and a signal waveform formed by the signal voltage averaged at every predetermined time are averaged to obtain an average voltage value of the entire waveform. Averaging means (16c),
The output signal from the average value detecting means (12c) and the output signal from the averaging means (16c) are compared, and a pulse signal is output and integrated every time the former signal voltage exceeds the latter signal voltage. Peak frequency detection means (41) for obtaining the appearance frequency of a salient signal based on the number of pulse signals per unit time
c, 42c) and the respective output signals from the average value detecting means (12c) and the peak value detecting means (14c), the difference between the peak value and the average value and the ratio of the average value obtained by multiplying the coefficient are different. It is calculated as a sound factor (NF), and when the abnormal noise factor (NF) exceeds a set threshold value, it is determined that there is an abnormal operation sound, and the rotation speed detecting means (2) and the peak frequency detecting means (41c). , 42c) based on each output signal from the output discriminating means 42, 42c), and a calculation discriminating means (30) for calculating the peak frequency per one rotation as the peak occurrence frequency.

(Operation) According to the abnormal sound discriminating apparatus configured as described above, the average value detecting means (12c) converts the detected operating sound into an average signal for each predetermined frequency band, thereby reducing the average signal level. The signal waveform is obtained, and the peak value detecting means (14c)
Detects the level of a signal that is more prominent than the average level signal waveform, and when these levels exceed the normal values, the operation determination means (30) determines that the continuous abnormal noise is generated by the former,
It is assumed that intermittent noise is generated by the latter.

Then, when it is determined that the intermittent noise is generated, the calculation determining means (30) causes the peak frequency detecting means (41c, 42c).
In the relationship between the peak frequency obtained by (1) and the engine rotation speed detected by the rotation speed detecting means (2), the peak occurrence frequency, that is, the peak occurrence frequency in one operating cycle of the engine is obtained.

(Embodiment) In FIG. 1, reference numerals 1, 2 and 4 are the engine, the rotation speed detector and the operation sound detector, respectively, and the rotation speed detector 2 is arranged to face the starter ring gear 3 of the engine 1. A pulse signal corresponding to the number of teeth of the ring gear 3 is output every time the gear rotates once. Operating sound detector 4
The charge amplifier 5 for amplifying the detection signal from is similar to that of the conventional device shown in FIG. 6, and the frequency analyzer 6 having the bandpass filters 6a to 6f having the one octave structure is also the same as that of the conventional device. Similarly, the detection signal from the detector 4 via the charge amplifier 5 is input to each of the band pass filters 6a to 6f.

11c is a double-wave rectifier that double-wave rectifies the frequency signal that has passed through the bandpass filter 6c, 12c is an average value detector that averages the rectified signal from the double-wave rectifier 11c as an instantaneous level every predetermined time, and 13c is an average value detector. The auditory correction of the output signal from the detector 12c, specifically, the auditory corrector composed of a low-pass filter that cuts the fluctuations in the high frequency part to make the fluctuations in the audible sound region clear, 14c is the auditory corrector When the signal voltage value at a particularly prominent portion of the output signal waveform is detected, that is, when a signal showing a voltage that is particularly higher than the average voltage among the hearing-corrected signals is detected, the peak value detector that outputs the signal, 15c It is an averaging circuit that determines an average voltage value of each signal voltage value detected by the peak value detector 14c. Further, 16c is an averaging circuit for averaging (converting into a DC voltage value) the output signal waveform from the hearing compensator 13c, and this averaging circuit 16c is for averaging the signal of the frequency band through the band pass filter 6c. The level is averaged.

A double-wave rectifier 11c following the bandpass filter 6c, an average value detector 12c, an auditory sense corrector 13c, a peak value detector 14c,
The signal processing system including the averaging circuits 15c and 16c is provided for each of the other band pass filters.

Reference numeral 20 denotes an A / D conversion of the output voltage level from each signal processing system (referred to as a channel) following each band pass filter 6a to 6f, specifically, the output voltage level from the averaging circuit (15c, 16c) in each channel. A reference numeral 30 denotes an A / D converter, which is an arithmetic / discrimination unit composed of a microcomputer or the like for discriminating the occurrence of abnormal noise based on the output data from each channel via the A / D converter 20. Then, the discrimination result of the arithmetic / discrimination unit 30 is output to the printer 31 and displayed on the CRT display device 32.

Here, the arithmetic / discrimination unit 30 uses the peak value data from the averaging circuit (15c) in each channel and the averaging circuit (16c).
The average value data from c) is sampled a predetermined number of times in a predetermined cycle, and the average values are averaged to calculate average peak value data P and average average value data A. Then, based on the average peak value data P and the average average value data A, the intermittent abnormal noise factor NFd
Is calculated according to NFd = (PA) / A ... (1), while continuous abnormal noise factor NFr is calculated according to NFr = (A * 10) / (PA) ... (2). When each of the abnormal noise factors NFd and NFr exceeds a predetermined threshold (experimentally determined), various (intermittent and continuous) abnormal noises are discriminated.

Next, a specific operation will be described.

It is assumed that the engine 1 is in an idling state and the operation of the engine is accompanied by intermittent noise.

The frequency component corresponding to the engine operating sound is separated by the frequency analyzer 6 as a signal in each frequency band, and the separated signals are processed by the respective channels,
The peak value and the average value of the separated signals are output from the averaging circuits (15c) and (16c). At this time, the output signal from each average value detection circuit (12c) is, for example, an intermittent noise as shown in FIG. 2 when looking at the signal passing through the bandpass filters 6d to 6f (2KHz, 4KHz, 8KHz). Corresponding to the discontinuity of, the waveform becomes particularly prominent. Then, the peak value detector (14c) detects the signal levels Vp (1), Vp (2), ... Which are particularly prominent as described above, and the averaging circuit (15c) detects the peak value detector (14c). Detection value from Vp
(1), Vp (2), ... are averaged and the average value is output. On the other hand, each averaging circuit (16c) averages the signal waveform as shown in FIG.
Is output.

In the process in which the signals of the respective frequency bands separated by the frequency analyzer 6 are processed by the respective channels as described above, the arithmetic / discrimination unit 30 operates in the flow chart shown in FIGS. 3 and 4. Therefore, it operates. The flow shown in FIG. 3 is the main flow, and the flow shown in FIG. 4 is a subroutine corresponding to the data sample shown in FIG.

The output values from the averaging circuits (15c) and (16c) of each channel, that is, the peak value and the average value are sampled via the A / D converter 20. Specifically, as shown in FIG. 4, the register for storing the data from each channel is reset, and the peak value and the average value are set for each channel while inputting the peak value and the average value. Capture as data. Then, when the data acquisition is completed a preset number of times for all channels (returning from the subroutine to the main flow), the average peak value data P is calculated from the sampled peak value and the sampled average value is calculated. The average value data A is calculated. Then, based on the average peak value data P and the average average value data A, the intermittent abnormal noise factor NFd and the continuous abnormal noise factor NFr are calculated according to the equations (1) and (2).

When the intermittent abnormal noise factor NFd and the continuous abnormal noise factor NFr are calculated for each channel as described above, the intermittent abnormal noise factor NFd is compared for each channel with a predetermined threshold value,
When the factor value exceeds the threshold value, it is determined that there is an intermittent sound and a failure determination is made, while when the factor value is less than or equal to the threshold value, it is determined that there is no intermittent sound. And
After the above determination, the continuous abnormal noise factor NFr is compared with another predetermined threshold value, and when the factor value exceeds the threshold value, it is determined that there is a continuous sound and the rejection is determined.
When the factor value becomes less than or equal to the threshold value, it is determined that there is no continuous sound and the engine is judged to be acceptable.

When the comprehensive judgment for the intermittent abnormal noise and the continuous abnormal noise is completed in this way, the judgment result is printed out on the printer device 31 and displayed on the CRT display device 32.

Further, in FIG. 1, 41c is a peak frequency detector that outputs a pulse signal each time the instantaneous level of the output signal from the average value detector 12c exceeds the output signal level from the averaging circuit 16c, and 42c is the peak frequency detector. An F-V converter 43c for converting into an analog voltage value proportional to the number of pulses generated per unit time based on the pipulse signal from the frequency detector 41c
Is an averaging circuit for averaging the output signal waveform from the FV converter 42c to determine an average voltage value according to the peak frequency signal output. These peak frequency detectors 41c, F-
The signal processing system (channel) composed of the V converter 42c and the averaging circuit 43c is provided for each of the other band pass filters.

Further, 44c is an FV converter for converting the pulse signal from the rotation speed detector 2 into an analog signal, and 45c is this FV converter 4
This is an averaging circuit that averages the output signal waveform of 4c to determine an average voltage value according to the rotation speed of the engine 1.

The respective average voltage outputs from the averaging circuit 45c and the averaging circuit (43c) of the respective channels are digitally converted by the A / D converter.

The calculation / discrimination unit 30 calculates the peak occurrence frequency for those that fail the intermittent sound determination according to the main flow shown in FIG. 3 and the subroutine shown in FIG. That is, by resetting the register for storing the data from each channel, and designating the channels in which the intermittent noise factor NFd value exceeds the threshold value, the averaging circuit (43c) and rotation speed detection of the channels for each channel are detected. The output value from the averaging circuit 45c of the signal processing system subsequent to the device 2 is captured as peak frequency data Rn and rotation speed data E via the A / D converter 20, respectively, and the number of times set in advance for all channels specified by this capture is set. When only this is finished, the peak occurrence frequency Rn from these sampled data Rn and E
Calculate / E (Fig. 3). After this calculation is completed, the engine is subjected to the judgment of the continuous sound, and the calculation result is output together with the judgment result to output the CRT display device.
32, printer 31 etc. display and record.

The embodiment is as described above.

In this embodiment, the presence or absence of abnormal noise is determined by the abnormal noise factors NFr and NFd, that is, the fluctuation rate of the waveform level as is clear from the equations (1) and (2). Even if the detection signal output fluctuates due to improper mounting of the device 4 or the detection system thereof changes over time, the abnormal noise factor is rarely affected. Therefore, in addition to improving discrimination accuracy, low speed, high speed, acceleration,
By adding inspection items such as deceleration, the assurance accuracy of the engine can be increased and the analysis of abnormal noise sources can be made easier.

In the present embodiment, even for continuous abnormal sounds, the abnormality determination is made based on the difference between the peak value and the average value and the ratio of the average value, but in order to realize an actual device, ,
As for the continuous abnormal noise, the abnormality determination may be performed based on only the average value as in the conventional case.

The average value output in the averaging circuit (15c, 16c) shown in FIG. 1 is not limited to a simple average, and various well-known average output values may be obtained. The same applies to the average value of the input data (peak value, average value) in the abnormal sound discrimination unit 30.

(Effect) As described above, according to the present invention, the average value detecting means (12c) obtains the signal waveform of the operating sound for each predetermined frequency band, and the peak value detecting means (14)
c) detects the level of the signal that is more prominent than the average level signal waveform, and when these levels exceed the normal value,
The operation determining means (30) can determine that a continuous abnormal noise is generated by the signal waveform and that an intermittent abnormal noise is generated by the protruding signal, and when the intermittent abnormal noise is generated, a calculation is performed. The discriminating means (30), in the relationship between the peak frequency obtained by the peak frequency detecting means (41c, 42c) and the engine rotational speed detected by the rotational speed detecting means (2), shows the peak occurrence frequency, that is, one operating cycle of the engine. The frequency of peak occurrence in the inside can be obtained.

As described above, the presence or absence of abnormal noise is discriminated based on the fluctuation rate of the waveform level, so that it is less affected by the mounting state of the detector, the temporal change of the detection system, etc., and the discrimination accuracy is improved. be able to.

[Brief description of drawings]

1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram showing an example of the output signal waveform of the average value detector in FIG. 1, FIG. 3, FIG. 4 and FIG. FIG. 6 is a flow chart showing the operation of the abnormal sound discriminator in FIG. 1, and FIG. 6 is a block diagram showing an example of a conventional device. 1 ... Engine, 2 ... Rotation speed detector 4 ... Operating noise detector, 6 ... Frequency analyzer 12c ... Average value detector, 14c ... Peak value detector 15c, 16c ... Averaging circuit 20 …… A / D converter, 30 …… Calculator / discrimination unit 41c …… Peak frequency detector 43c, 45c …… Averaging circuit

Claims (1)

[Claims] 1. A device for separating a signal obtained by detecting an operating noise of an engine into signals in a predetermined frequency band and determining the presence or absence of abnormal noise based on the separated signals, the rotational speed of the engine being detected. Rotation speed detecting means (2)
An average value detecting means (12c) for obtaining an instantaneous signal voltage by averaging the signals of the predetermined frequency band rectified after separation, and an average value of the signal voltage averaged every predetermined time. A peak value detecting means (14c) for detecting a high voltage value protruding from the signal waveform to be formed and a signal waveform formed by the signal voltage averaged every predetermined time are averaged to obtain an average voltage value of the entire waveform. The output signal from the averaging means (16c) and the average value detecting means (12c) is compared with the output signal from the averaging means (16c), and each time the former signal voltage exceeds the latter signal voltage. A peak frequency detecting means (41) for outputting a pulse signal, integrating the pulse signal, and obtaining the appearance frequency of the protruding signal based on the number of pulse signals per unit time.
c, 42c) and each output signal from the average value detecting means (12c) and the peak value detecting means (14c), the difference between the peak value and the average value and the ratio of the average value obtained by multiplying the coefficient are different. It is calculated as a sound factor (NF), and when the abnormal noise factor (NF) exceeds a set threshold value, it is determined that there is an abnormal operation sound, and the rotation speed detecting means (2) and the peak frequency detecting means (41c). , 42c) based on the respective output signals from the output discriminating means, and the operation discriminating means (30) for computing the peak frequency per one rotation as the peak occurrence frequency.