JPH02205727A - Apparatus for detecting abnormality of bearing - Google Patents

Abstract

PURPOSE:To obtain a detecting apparatus which can be used in a broad range regardless of the kind of machines, the kinds of bearings, number of rotations and the like by using an automatic-gain-control amplifier whose gain is controlled by an electric signal which is an object to be judged. CONSTITUTION:A pickup 1 transduces the mechanical vibration of a bearing into an electric signal and outputs the signal. Said output is inputted into an automatic-gain-control amplifier 2. The output of the amplifier 2 is inputted into a bandpass filter 3. The output of the filter 3 is inputted into a means for judging the presence or absence of the bearing comprising an envelop circuit 4, an effective value operating device 6 and an alarm circuit 7. The output of the filter 3 is inputted into an effective value operating device 5, and appropriate operation is performed. The result is supplied to the gain control terminal of the amplifier 2. When the vibration of the bearing is large, the gain of the amplifier 2 becomes small automatically, and the amplifier 2 is not saturated. When the vibration of the bearing is small, the gain of the amplifier 2 becomes large automatically. Thus the output of the amplifier that is sufficient for judgement and the specified S/N are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an abnormality detection device that detects flaking, scratches, etc. on a bearing.

(Prior art) Conventionally, as this type of abnormality detection device, for example,
There is a "bearing flaw detection device" disclosed in Japanese Patent No. 8-127142. FIG. 2 is a block diagram of the device.

In the figure, 2! 22 is an amplifier that amplifies the output of this pickup 21, and 23 is a drive system from the output of the amplifier 22. This is a bandpass filter that removes noise generated from other mechanical systems.

The output of the bandpass filter 23 is supplied to an envelope circuit 24 and an effective value calculator 26 having the configuration shown in FIG. 3, and the output of the envelope circuit 24 is supplied to an effective value calculator 25.

In the divider 27, an operation is performed to divide the output of the effective value calculator 25 by the output of the effective value calculator 26, and the output is supplied to the indicator 28 and the alarm circuit 29.

With this configuration, the output of the divider 27 is approximately constant during normal times even for bearings of different types of machines, and in the event of an abnormality such as a scratch on the bearing, the output of the band pass filter 2
On the output side of 3, a waveform in which pulses with large amplitudes are intermittently added to the normal vibration waveform is obtained, the output of the effective value calculator 25 increases, and the output of the divider 27 increases beyond the above-mentioned constant value. Then, the bearing abnormality is displayed on the indicator 28 and the alarm circuit 2
Announcement will be made at 9.

(Problems to be Solved by the Invention) However, with the conventional device, depending on the machine to be diagnosed, the vibration of the bearing may be too large and the amplifier may be saturated, or the vibration of the bearing may be too small and the amplifier may not be able to be used for diagnosis. There is a problem in that the vibration range of the bearing that can actually be diagnosed is limited and the objects of diagnosis are limited because the output cannot be obtained or the predetermined S/distance cannot be obtained.

The present invention has been made to solve such problems, and an object of the present invention is to provide a bearing abnormality detection device that can be used over a wide range of applications regardless of the type of machine, type of bearing, rotation speed, etc. It is.

[Means to solve the problem]

In order to achieve the above object, the present invention uses an automatic gain control amplifier whose gain is controlled by an electric signal to be determined. Specifically, a bearing abnormality detection device is configured as follows. .

That is, a pickup that converts the mechanical vibration of the bearing into an electrical signal and outputs it, an automatic gain control amplifier that inputs the output of the pickup, and a band-pass filter or high-pass filter that inputs the output of the automatic gain control amplifier. a means for inputting the output of the filter to determine whether there is an abnormality in the bearing; and a stage for inputting the output of the filter, performing appropriate calculations, and supplying the output to the gain control terminal of the automatic gain control amplifier. Be prepared.

With the above configuration, when the vibration of the bearing is large, the gain of the automatic gain control amplifier is automatically reduced so that the amplifier does not become saturated, and when the vibration of the bearing is small, the gain of the automatic gain control amplifier ( q is automatically increased to obtain an amplifier output sufficient for determination and a predetermined S/interval.

〔Example〕

The present invention will be explained below with reference to Examples.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

In the figure, 1 is a pickup that converts the mechanical vibration of the bearing into electrical vibration and outputs it, and 2 is an automatic gain control amplifier (VCAIOIA manufactured by Tokyo Musen Kizai Co., Ltd.) that amplifies the output of this pickup 1. 3 is the amplifier 2. 1 to 15k1 removes noise generated from the drive system and other mechanical systems from the output
1□ band pass filter, 5 band pass filter 3
This is an effective value calculator that calculates the effective value of the output of the automatic gain control amplifier 2 and supplies it to the gain control terminal of the automatic gain control amplifier 2.

4 is an envelope circuit configured as shown in FIG. 3 which inputs the output of the band-pass filter 3; 6 is an effective (a) calculator which inputs the output of the envelope circuit 4; and 7 is an input which inputs the output of the effective value calculator 6. 4.6.7 constitutes a means for determining the presence or absence of an abnormality in the alarm if1 circuit which issues an alarm by lamp or contact output when the value exceeds a predetermined value.

Resistor 33 in envelope circuit 4. The time constant of the capacitor 32 is selected to be semi-fixed, for example, about 1 to 10 m5ec, which is larger than the period of the vibration waveform during normal times and smaller than the period of pulses during abnormal times.

With this configuration, under normal conditions, an output signal with a constant effective value path is obtained on the output side of the bandpass filter 3, and when there is an abnormality such as flaking or scratches on the bearing, the bandpass filter 3 3, a waveform in which large amplitude pulses are intermittently added to the normal vibration waveform is obtained, the envelope of the output of the envelope circuit 4 swells, and the output of the effective value calculator 6 increases.

When the output of the effective value calculator 6 exceeds a predetermined value, the alarm circuit 7
This will cause notifications such as lighting up a lamp and outputting a contact output, and an abnormality in the bearing will be detected. Note that the predetermined value is determined in advance through experiments.

When the vibration of the bearing to be determined is large, the gain of the automatic gain control amplifier 2 is reduced, and when the vibration of the bearing is small, the gain of the amplifier 2 is increased, so there is no need to manually switch the measurement range. , the vibration of the bearing is too large and the amplifier 2 is saturated.

Abnormalities cannot be detected because the bearing vibration is too small and a sufficient signal cannot be obtained or a predetermined S/N ratio cannot be obtained, and the output side of the bandpass filter 3 has an approximately constant effective value. Since only a signal of 1 is obtained, there is no need to use a divider, and the circuit for determining the presence or absence of an abnormality is simplified.

In the above embodiments, the effective value is calculated by the calculator 5.6, but it is not limited to the effective value, but is an average value.

It is also possible to calculate the root mean value, etc., or the filter 3
In addition to the band pass filter, a high pass filter may be used.

(Effects of the Invention) As explained above, according to the present invention, since the automatic gain control amplifier whose gain is controlled by the filter output is used, it is possible to Regardless of the situation, it is possible to detect an abnormality in the bearing, and since the filter output is approximately constant, the circuit for determining the presence or absence of an abnormality can be of a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment, FIG. 2 is a block diagram of a conventional example, and FIG. 3 is a circuit diagram of an envelope circuit. In the figure, 1 is a pickup, 2 is an automatic gain control amplifier, and 3
is a bandpass filter, 5 is an effective value calculator, 4, 6.7
is a means for determining the presence or absence of an abnormality.

Claims (1)

[Claims] (1) A pickup that converts the mechanical vibration of the bearing into an electrical signal and outputs it, an automatic gain control amplifier that inputs the output of the pickup, and a bandpass filter or high-pass that inputs the output of the automatic gain control amplifier. A filter, a means for inputting the output of the filter to determine whether there is an abnormality in the bearing, and a means for inputting the output of the filter, performing appropriate calculations, and supplying the output to the gain control terminal of the automatic gain control amplifier. A bearing abnormality detection device characterized by comprising: