JPH03148035A - Apparatus for detecting abnormality of bearing - Google Patents

Abstract

PURPOSE:To make it possible to arrange an apparatus in a limited space by providing means such as an acceleration sensor for detecting the vibration acceleration of a bearing, a device for measuring the mechanical vibration based on the detected value in a low frequency band from the sensor, and a device for measuring acoustic emission in a high frequency band. CONSTITUTION:A piezoelectric type acceleration sensor 10 is provided, and its output is supplied to band pass filters 5a and 5b through a broad-band preamplifier 11. The detected value from the sensor 10 is amplified in the amplifier 11. Thereafter, the low-frequency-band signal corresponding t mechanical vibration is extracted through the filter 5a. Meanwhile, the output from the amplifier 11 passes through the filter 5b, and the signal in the high-frequency band corresponding to acoustic emission AE is extracted. The peak value of the mechanical vibration generated in a bearing 1 is operated in a peak operator 7d based on the low-frequency band signal. The AE generating number per unit time is counted in an event counter 9 based on the high- frequency-band signal. In this way, the abnormality of the bearing at the final stage can be detected based on the results of the operations in the operators 7a and 7d. The abnormality of the bearing 1 at the initial stage can be detected based on the result of the operation of an effective value operator 7b and the counted value of the counter 9.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an improvement of a device for detecting abnormalities in a bearing based on mechanical vibration and acoustic emission (hereinafter referred to as AE). In particular, the space of the mounting portion can be saved and the labor involved in wiring and the like can be simplified.

[Conventional technology]

While AE is suitable for detecting initial damage (such as the occurrence of minute cracks), it cannot detect subsequent abnormalities unless the damage progresses after a crank occurs. Further, although mechanical vibration cannot detect early damage, it is useful for detecting terminal abnormalities such as occurrence of flaking. In other words, in order to accurately understand bearing abnormalities from the initial stage to the final stage, it is necessary to monitor both AE and mechanical vibration.

Therefore, as a conventional device for detecting abnormalities in a bearing by monitoring both mechanical vibration and AE, there is a device shown in FIG. 3.

This means that initial damage to bearing 1 is detected based on AE,
This device detects terminal damage based on mechanical vibration, and the bearing 1 includes, for example, an outer ring (not shown) of the bearing 1 or a housing (not shown) that supports the outer ring in close contact with the bearing 1. An acceleration sensor 2 and an AE sensor 3 are provided.

The detection signal of the acceleration sensor 2 is amplified by a preamplifier 4a, and is then amplified in a mechanical vibration frequency band (for example, 1 to 10
Filter processing is performed by a band pass filter 5a that extracts a signal of about kHz), and then a main amplifier 6
a and is further amplified and supplied to the effective value calculator 7a.

The effective value calculator 7a calculates the effective value of the supplied signal (that is, the mechanical vibration occurring in the bearing 1).

On the other hand, the detection signal of the AE sensor 3 is amplified by the preamplifier 4b, and then output to the 8E frequency band (for example, 200kHz).
Filter processing is performed by the bypass filter 5b which extracts the above signal, and the signal is further amplified by the main amplifier 6b and supplied to the effective value calculator 7b and the envelope detection circuit 7c.

The effective value calculator 7b calculates the effective value of the supplied signal (ie, the AE occurring in the bearing 1).

Further, the output of the envelope detection circuit 7c is compared with a reference value by a comparator 8, and based on the result of the comparison, an event counter 9
However, if the output of the envelope detection circuit 7c exceeds the reference value (
That is, the number of AEs occurring per unit time is counted.

Therefore, by monitoring the outputs of the effective value calculator 7b and the event counter 9, it is possible to detect the formation or growth of a small rank that occurs in the initial damage of the bearing 1, and the output of the effective value calculator 7a can be detected. By monitoring the output, it is possible to detect flaking or the like that occurs when the bearing 1 is damaged in its final stages.

[Problem to be solved by the invention]

However, the conventional device described above uses two sensors: an acceleration sensor 2 for detecting mechanical vibrations and an AB sensor 3 for detecting AE.
This increases the amount of sensor cable wiring, which poses a problem in that it is difficult to install it around the bearings of mechanical devices where it is difficult to obtain a large space.

The present invention has been made by focusing on the problems of the conventional technology, and provides a bearing abnormality detection device that can be easily installed even around the bearings of mechanical devices where it is difficult to obtain a large space. The purpose is to

[Failure to solve the problem]

In order to achieve the object -1-, the present invention provides an apparatus for detecting an abnormality in a bearing based on mechanical vibration and AE, which includes an acceleration sensor that detects vibration acceleration generated by the bearing, and an acceleration sensor that detects vibration acceleration generated by the bearing. vibration measuring means for measuring the mechanical vibration based on a detected value in a low frequency band of the acceleration sensor;
AE measurement means for measuring E was provided.

[Effect]

In the present invention, mechanical vibration is measured based on the detected value in the low frequency band of the acceleration sensor, and AE is measured based on the detected value in the high frequency band of the acceleration sensor.
By simply providing one acceleration sensor, abnormalities in the bearing from the initial stage to the final stage can be detected.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. Note that the same components as in FIG. 3 are designated by the same reference numerals.
The redundant explanation will be omitted.

That is, in this embodiment, a piezoelectric type acceleration sensor 10 is provided, and the output of the acceleration sensor 10 is sent to a broadband preamplifier 1.
1 to a bandpass filter 5a and a bypass filter 5b.

Note that the wideband preamplifier 11 needs to have performance capable of wideband signal amplification ranging from the mechanical vibration frequency band (about 1 to 10 kHz) to the AE frequency band (about several hundred kHz).

FIG. 2 is a graph showing the frequency response in a high frequency band of the acceleration sensor 10 (see solid line) and the AE sensor (see broken line).

Conventionally, the acceleration sensor 10 has a high frequency band (several hundred kHz).
) have received little attention. However, as shown in FIG. 2, the response sensitivity of the acceleration sensor 10 in the high frequency band is slightly inferior to that of the AE sensor, but it has a certain degree of response sensitivity, and the difference in performance with the AE sensor is as follows. This can be sufficiently covered by increasing the amplifier gain in the latter stage.

Therefore, in this embodiment, the detected value of the acceleration sensor 10 is
After being amplified by the wideband preamplifier 11, a low frequency band signal corresponding to mechanical vibration is extracted by the bandpass filter 5a, and this is further amplified by the main amplifier 6a.
Based on the output of the main amplifier 6a, the effective value calculator 7a calculates the effective value of the mechanical vibration occurring in the bearing 1, and the peak value calculator 7d calculates the effective value of the mechanical vibration occurring in the bearing 1. Calculate the peak value of

On the other hand, the output of the wideband preamplifier 11 is filtered in a bypass filter 5b to extract a high frequency band signal corresponding to AE, similar to the conventional technique described above, which is further amplified in the main amplifier 6b to produce an effective The signal is supplied to a value calculator 7b and an envelope detection circuit 7c. Then, the A occurring in the bearing 1 in the effective value calculator 7b
The effective value of E is calculated, passes through an envelope detection circuit 7C and a comparator 8, and then an event counter 9 counts the number of AE occurrences per unit time.

Therefore, it is possible to detect the terminal abnormality of the bearing l based on the calculation results of the effective value calculation unit 7a and the peak value calculation unit 7d, and the calculation results of the effective value calculation unit 7b and the event counter 9
An initial abnormality in the bearing 1 can be detected based on the count value of .

In this way, in the above embodiment, the acceleration sensor 10
Since the mechanical vibration and AE generated in the bearing 1 are measured from the detected values, abnormalities in the bearing 1 from the initial stage to the terminal stage can be detected. The number of sensors arranged around the I can be reduced, and the amount of wiring such as sensor cables can also be reduced accordingly, so it can be used even around the bearing 1 of a mechanical device where it is difficult to obtain a large space. , can be installed relatively easily.

Furthermore, since it is possible to simultaneously measure four mechanical vibrations and AE, it becomes possible to detect a wide range of abnormalities in the bearing 1 from the initial stage to the final stage with one device.

Here, in the above embodiment, the broadband preamplifier 11, the bandpass filter 5a, and the main amplifier 6a.

A vibration measuring means is constituted by the effective value calculator 7a and the peak value calculator 7d, which includes a wideband preamplifier 11, a bypass filter 5b, a main amplifier 6b, and an effective value calculator 7a.
, the envelope detection circuit 7c, the comparator 8, and the event counter 9 constitute an AE measuring means.

In the above embodiment, a case where a piezoelectric type acceleration sensor IO is provided has been described, but other types of acceleration sensors may be used.

〔Effect of the invention〕

As explained above, according to the present invention, mechanical vibration and AE of the bearing are measured using one acceleration sensor, and abnormalities of the bearing from the initial stage to the terminal stage are detected. Compared to equipment, fewer sensors are installed around the bearing, and the amount of wiring such as sensor cables is also reduced, so it can be used even around the bearing of a mechanical device where it is difficult to find a large space. It has the advantage that it can be arranged relatively easily.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention;
The second part is a graph showing the frequency response of the acceleration sensor and the A and E sensors in a high frequency band, and FIG. 3 is a block diagram showing the configuration of a conventional device. ■...Bearing, 5a...Band pass filter, 5b...
... Bypass filter, 6a, 6b... Main amplifier, 7a, 7b... Effective value calculator, 7C... Envelope detection circuit, 7d... Peak value calculator, 8... Comparator,
9...Event counter.

Claims (1)

[Claims] (1) A device that detects abnormalities in a bearing based on mechanical vibration and acoustic emissions, which includes an acceleration sensor that detects vibration acceleration generated by the bearing, and a detection value of the acceleration sensor in a low frequency band. A bearing comprising: a vibration measuring means for measuring the mechanical vibration; and an acoustic emission measuring means for measuring the acoustic emission based on a detection value in a high frequency band of the acceleration sensor. Anomaly detection device.