JPS622243B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an abnormality detection device for a rotating mechanism that improves the accuracy of abnormality detection.

As a conventional abnormality detection device for a rotating mechanism such as a gear, there is, for example, one that performs analysis using a frequency analyzer (spectrum analyzer).

This consists of a sound sensor that detects the rotational sound vibration generated from the transmission, which is a gear rotation mechanism, a frequency analyzer that analyzes the frequency of the rotational sound vibration and outputs a rotational sound signal in each frequency band, and a rotational sound signal. It is equipped with a conversion circuit that converts the data into a fast Fourier series, and a circuit that samples the fast Fourier series 50 times per second, and determines whether the data is normal or abnormal based on the data sampled by the sampling circuit and output.

However, with conventional abnormality detection devices, there is a risk that the sound sensor may detect noise other than the rotational sound of the transmission (for example, sudden noise in a factory), resulting in erroneous detection. In addition, it was not easy to determine whether something was normal or abnormal.

In view of the above, the present invention subtracts the count value by a noise sensor from the count value by a rotation sound sensor within a predetermined detection time in order to improve the accuracy of detecting abnormalities in rotating mechanisms such as gears. An object of the present invention is to provide an abnormality detection device for a rotating mechanism that makes it easy to determine whether the rotating mechanism is normal or abnormal by making a judgment based on a count value that has no influence.

The abnormality detection device for a rotating mechanism according to the present invention will be explained in detail below.

Figures 1A and 1B show an embodiment of the present invention, which is a transmission sound microphone using a parabola, which is installed close to the top of the transmission to input the rotational sound of the rotating mechanism, for example, the transmission. The band of the sensor 1, the amplifier 2 that amplifies the output of the transmission sound sensor 1 (hereinafter referred to as the rotation signal), and the signal separation unit 30 that separates the output of the amplifier 2 into electrical signals of a predetermined number of frequency bands. The filters 31, 32...35, the detection and counting circuits 41, 42...45 of the counting section which detects and counts rotational noise by inputting electric signals of each frequency band, and mainly detect sounds other than the rotational noise of the transmission, such as , a noise sensor 21 (installed approximately 2 m from the transmission sound sensor 1) detects sudden noise in the factory such as when a forklift passes by, and the output of the noise sensor 21 is (hereinafter referred to as a noise signal). Amplifier 2 that amplifies
2, bandpass filters 36, 37, ... 39 of the signal separation section that separates the output of the amplifier 22 into electrical signals of the predetermined number of frequencies, and the filters 36, 37.
...39, a detection and counting circuit 46 of a counting section that detects and counts sudden noise by inputting electric signals of each frequency band,
47...49, and the detection and counting circuits 41, 42...45
The count values from the detection and counting circuits 46, 47, .
... 45 and an arithmetic control circuit (for example, a microcomputer) 10 that controls the detection operations of the detection and counting circuits 46, 47, . . . 49. The detection and counting circuit 41 includes a rectifier circuit 4 that rectifies the output of the bandpass filter 31, a waveform shaping circuit 5 that shapes the waveform of the rectified signal, and a switch 6 having contacts a and b (this switch 6 is ), and a comparator circuit 7 that compares a reference signal at a level predetermined by a control signal from the arithmetic control circuit 10 with the signal output from the circuit 4 or the waveform shaping circuit 5. , and a counter 8 for counting the pulse output of the comparator circuit 7. Other detection and counting circuit 4
45 and 46, 47, . . . 49 also have the same configuration as the detection and counting circuit 41. In addition, the predetermined level of the reference signal mentioned above is set in the noise detection circuit to a level slightly higher than the background noise in the factory that is constantly occurring, and the comparator 7 is set to a pulse level when this background noise occurs. Set the pulse so that it does not generate pulses, and only generates pulses for sudden sounds. In addition, in a circuit that detects rotational noise, for example, a sine wave of the same magnitude is input to each frequency band of the signal separation unit 30, and each reference signal is set so that uniform pulses are generated. . In this way, the reference levels of the detection and counting circuits 41, 42...45 and the reference levels of the detection and counting circuits 46, 47...49 are set to different levels, respectively. Further, as shown in FIG. 1B, the arithmetic control circuit 10 inputs the count value of the counter 8 based on the rotation signal to the addition terminal, and calculates the count value of the counter 8 in the frequency band corresponding to the frequency band of the counter 8 based on the noise signal. (For example, the detection counting circuit 46
an addition/subtraction circuit 51 that adds and subtracts a counted value (included in ) by a constant input to a subtraction terminal (the reason will be explained later); and a determining means 90 that determines whether the added and subtracted value is within a predetermined width. have.

The reason why a certain constant is applied to the pulse determined according to the noise signal is that even if a sudden sound occurs and one noise pulse is counted, for example, that pulse is not necessarily counted as one pulse in the rotation signal. That is, since a parabola is used to input the rotation signal, the S/N ratio between the rotation signal and the noise signal can be increased.

Next, the arithmetic control circuit 10 will be explained with reference to FIG.

Components that are the same as in FIG. 1 are designated by the same numbers.
However, the interface 9 is omitted.

An addition/subtraction circuit 51 (similar to Addition and subtraction circuits 52 to 55) are provided for each frequency band. The count value subtracted by the addition and subtraction circuits is sent to the addition and subtraction circuits 51 to 55.
is held in the holding circuits 61 to 65 of the determination means 90 correspondingly, and is compared for each frequency band with master values 71 to 75, which are predetermined with a range depending on the rotating machine to be measured. If there is a value exceeding this value, the arithmetic control circuit 10 determines that there is an abnormality.

In the above configuration, FIGS. 1, 2, 3,
This will be explained using FIG. The sound (mainly rotational sound) detected by the transmission sound sensor 1 is amplified to several volts by the amplifier circuit 2 as a rotational signal. This amplified rotational signal is separated into signals in 10 frequency bands by, for example, 10 stages of bandpass filters 31, 32, . do. For example, 500 Hz to 1 input to the detection and counting circuit 41
The rotation signal in the kilohertz frequency band is sent to the rectifier circuit 4.
The signal is rectified by the converter 6 and inputted to the comparator 7 either directly by the switch 6 or via the waveform shaping circuit 5.
The waveform shaping circuit 5 is used when the filtering effect by the first-stage bandpass filter 31 is insufficient. The comparator 7 compares the input electric signal V with the aforementioned reference signal V _R at a predetermined level, and outputs a pulse when V>V _R . The counter 8 counts the pulses and outputs the counted value to the addition terminal of the addition/subtraction circuit 11 . On the other hand, the noise signal converted from the sound (mainly sudden noise in the factory) detected by the noise sensor 21 is amplified by the amplifier circuit 22, and the noise signal is amplified by the 10-stage bandpass filter 3.
6, 37, . . . , 39, the signal is separated into signals of 10 frequency bands shown in FIG. Among these, 500
The signal in the frequency band from Hertz to 1 kilohertz is compared with a reference signal by the detection/counting circuit 46, and based on the comparison, the count value of the output pulse is sent from the detection/counting circuit 46 to the subtraction terminal of the addition/subtraction circuit 11. input. The addition/subtraction circuit 51 is a pulse counter that adds and subtracts the pulse P count value based mainly on the transmission rotation sound and the pulse count value mainly based on the sudden noise to cancel out the sound due to the influence of the sudden noise from the transmission rotation sound. The determination means 90 outputs a numerical value, and when the pulse count value is outside a value with a predetermined width, the determination means 90 outputs a signal, and this is performed for each frequency band.

The final determination of normality or abnormality is based on the type of rotating machine (e.g. engine, transmission) or
In the case of transmission, it differs depending on whether it is 1st stage, 2nd stage, etc., and is determined in advance for each case.

When a more detailed inspection is desired, the count values of each frequency band are sampled several times as shown in FIG. 5 and printed out. In other words, if the abnormality in the rotating machine is a "beating sound", the count value of 4KHz or more will increase, and the difference in the number of pulse counts when sampling several times in the same frequency band will be large. At this time, it can be determined that there is a "beat".

As explained above, according to the abnormality detection device for a rotating mechanism according to the present invention, determination is made based on the count value obtained by subtracting the count value by the noise sensor from the rotation sound count value by the rotation sound sensor within a predetermined detection time. As a result, it is possible to eliminate the influence of sudden noise in the factory and improve the accuracy of abnormality detection.

[Brief explanation of the drawing]

FIG. 1A is an explanatory diagram showing one embodiment of the present invention. FIG. 1B is an explanatory diagram showing the arithmetic control circuit of FIG. 1A.
FIG. 2 is a detailed view of FIG. FIG. 3 is an explanatory diagram showing signal separation by a bandpass filter. FIG. 4A is an explanatory diagram of a method for detecting an abnormal sound signal, and FIG. 4B is an explanatory diagram showing pulses output by this detection. FIG. 5 is an example of a printout format. Explanation of symbols, 1, 21...Sound sensor, 2, 22...
Amplifier circuit, 4... Rectifier circuit, 5... Waveform shaping circuit, 6
...Switcher, 7...Comparator, 8...Counter, 9...Interface, 10...Arithmetic control circuit, 51...Addition/subtraction circuit, 30...Signal separation section, 31, 32, 35,
36, 37, 39...band filter, 40...counting section,
41, 42, 45, 46, 47, 49...detection counting circuit, 51-55...addition/subtraction circuit, 61-65...holding circuit, 90...judgment means.

Claims (1)

[Scope of Claims] A first input section that is provided near a rotating mechanism and outputs a rotation signal corresponding to the rotational sound of the rotating mechanism; and a noise signal that corresponds to sudden noise around the first input section. a second input section that outputs the rotation signal and the noise signal, a signal separation section that separates the rotation signal and the noise signal into corresponding frequency bands, and an output of the signal separation section that is lower than a predetermined level for each frequency band. a counting section that counts a large number of times; a subtraction section that subtracts a count value based on the noise signal from a count value based on the rotation signal for each corresponding frequency band; and a subtraction section that subtracts a count value of at least 1 1. An abnormality detection device for a rotating mechanism, comprising: determination means for determining an abnormality when the frequency is outside a predetermined width in one frequency band, and outputting an abnormality signal.