JP2000321121A - Vibration sensing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration sensing apparatus of a low cost capable of preventing an erroneous alarm due to a vibration from an external another equipment by using a function of a general purpose vibration analyzer as a necessary minimum limit function. SOLUTION: The vibration sensing apparatus comprises a vibration sensing sensor mounted in a casing to sense a mechanical vibration to convert it into an electric signal, band pass filter circuits B, B' for amplifying the signal output from the sensor and then cutting an electric signal band corresponding to the vibration except a target, an integrating circuit 10 for rapidly calculating an acceleration only in the electric signal band to be a target, a comparing circuit 12 for comparing an output value of the circuit 10 with a preset alarm reference value, and an output circuit 14 for closing (opening) an output contact if the output value of the circuit 12 is the alarm reference value or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a vibration generated in a device, and more particularly, to monitoring an upper limit value of a vibration detected by the vibration detecting device, and opening a contact signal when the upper limit value is exceeded. (Close).

[0002]

2. Description of the Related Art A conventional vibration detecting device, as shown in FIG. 5, is a mechanical vibration detecting device 10 using a micro switch 101 which operates when vibration due to abnormal vibration exceeds a set value.
It has an amplification circuit, an arithmetic circuit, and an output circuit for electric signals obtained by zero and vibration sensors, amplifies and calculates the entire vibration frequency range, and issues an alarm when vibration acceleration due to abnormal vibration exceeds a set value. Electrical vibration detection device 200 as shown
There is. However, the mechanical vibration detecting device 100
Are mechanical contacts 102 such as microswitches 101
Therefore, false alarms are often generated by vibrations other than the specific frequency band to be monitored, which are generated due to rotational imbalance of the attached device. In addition, because it is not a measuring instrument, it was not possible to continuously indicate vibration acceleration. Further, the electric vibration detection device 200 has a vibration sensor, an amplification circuit, an arithmetic circuit, and an output circuit, and a method of amplifying and calculating the entire band of the vibration frequency is employed. As in the case, a false alarm is often generated by a vibration other than a specific frequency band to be monitored, which is generated due to a rotational imbalance of the attached device. Furthermore, an expensive fast Fourier transform frequency analyzer (FFT) is required to cut off the electric signal corresponding to the mechanical vibration other than the target, and the vibration detecting device has to be expensive.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and has the function of a general-purpose vibration analysis apparatus as a minimum necessary function, and has the advantage that it can be connected to other external devices. An object of the present invention is to provide an inexpensive vibration detection device capable of preventing a false alarm due to vibration.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the gist of the present invention is to provide a vibration detecting sensor A which is attached to a casing of an apparatus and detects mechanical vibration and converts it into an electric signal. And band-pass filter circuits B and B ′ for cutting the electric signal band corresponding to mechanical vibration other than the target after amplifying the electric signal output from the vibration detection sensor A; An integrating circuit 10 for calculating acceleration into speed, and a comparing circuit 1 for comparing an output value of the integrating circuit with a preset alarm reference value
2 and an output circuit 14 that closes (opens) an output contact when the output value of the comparison circuit 12 is equal to or greater than the alarm reference value. Here, the above-mentioned device means a device mainly having a rotary motion or a reciprocating motion, for example, a centrifuge or a compressor. The criteria for determining whether the vibration to be detected is abnormal
Instead of having an overall value that spans the entire vibration frequency band,
By providing a band filter with the center frequency of the natural vibration frequency generated when the rotating device or reciprocating device is operating normally, only the vibration value near the vibration frequency of the device whose vibration is to be monitored Can be monitored.

The gist of the invention according to claim 2 is that the set value of the band filter circuit can change the center frequency and the bandwidth.
The vibration detecting device according to the above. Since only the frequency in a specific frequency band is analyzed without analyzing the waveform such as the amplitude and frequency of the entire vibration, expensive measuring equipment is not required.

The gist of the invention according to claim 3 is that the comparison circuit is capable of setting a delay time to prevent a false alarm due to an instantaneous vibration change or disturbance. A vibration detecting device according to claim 1 or 2. Since the comparison circuit can set the delay time, it is possible to prevent an erroneous alarm due to an instantaneous vibration change or disturbance.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A vibration detecting device according to the present invention will be described with reference to the drawings. 1 is an external view of a vibration detection sensor according to the present invention, FIG. 2 is a block diagram of a signal path of the vibration detection sensor according to the present invention, and FIG. 3 is a signal path of a signal processing unit of the vibration detection device according to the present invention. FIG. 4 is a diagram showing a frequency response performance curve output when the frequency bandwidth is changed in nine steps using the band-pass filter of the vibration detecting device according to the present invention.

[0008] The vibration detecting device according to claim 1 of the present invention comprises:
A vibration detection sensor A that is attached to the casing of the device and detects mechanical vibration and converts it into an electric signal; and an electric signal corresponding to mechanical vibration other than the target after amplifying the electric signal output from the vibration detection sensor A. Band filter circuits B and B 'for cutting a band, an integration circuit 10 for calculating acceleration of only a target electric signal band into a speed, and comparing an output value of the integration circuit 10 with a preset alarm reference value. A comparison circuit 12 and an output circuit 1 that closes (opens) an output contact when an output value of the comparison circuit 12 is equal to or greater than an alarm reference value.
4 constitutes a main part.

The vibration detecting sensor A will be described with reference to FIGS. This vibration detection sensor A
As shown in FIG. 1, a box-shaped box 1 containing an acceleration sensor 1a and the like inside and having an output terminal 7 on the outside, and a box having a rotating motion, for example, for mounting the box 1 on a casing of a centrifuge. A box flange 4 provided with a plurality of holes 5, a truncated cone-shaped cable folder 2 screwed at a substantially central portion of the box 1 on the opposite side of the box flange 4, and protruding to the outside; The main part is composed of a cylindrical power plug 3 connected to the power supply 2 via a cable 6.

An electric signal including a low-frequency vibration frequency output from the acceleration sensor 1a accommodated in the box 1 in response to the mechanical vibration is provided in the box 1 as shown in FIG.
After being amplified by the amplifier 1b as shown in (1), it is applied to the low-pass filter 1c, further amplified by the subsequent amplifier 1d, and output from the output terminal 7. Here, by applying a low-pass filter 1c to the electric signal output from the acceleration sensor 1a, high-frequency noise of the device can be attenuated.

Next, a signal processing section for processing an electric signal output from the output terminal 7 will be described with reference to FIGS. 3 (a) and 3 (b). The signal processing unit for the electric signal includes a band-pass filter setting unit 8 or a band-pass filter setting unit 9 that is a band-pass filter circuit B or B ′, and an electric signal that has passed through the band-pass filter setting unit 8 or the band-pass filter setting unit 9. An integration circuit 10 for integration and an electrical signal corresponding to the mechanical vibration integrated by the integration circuit 10 are set by a reference electrical signal setting unit 11 for setting a comparison reference electrical signal corresponding to the mechanical vibration during steady operation. And a comparison circuit 12 for comparing with a reference value obtained by the comparison circuit 12. In order to determine whether the result is a "temporary abnormality" or a "real abnormality" even if the result of comparison by the comparison circuit 12 is determined to be "abnormal". A delay timer circuit 13 for setting the duration of the "abnormality" and an output circuit 14 having an on / off contact for transmitting the output signal of the comparison circuit 12 to an alarm circuit (not shown). But composed.

The above-mentioned band filter setting section 8 is provided with the configuration shown in FIG.
As shown in the figure, the transmission circuits 8a and 8a 'and the high-pass filter 8
b (hereinafter, referred to as HPF) and a low-pass filter 8c (hereinafter, referred to as “LPF”). Center frequency f, which is the vibration frequency inherent in the machine that monitors the vibration
The setting of c can be performed by setting rotary code switches 8d and 8d 'provided in the transmission circuits 8a and 8a'. It can be set in steps of 2 Hz in the range of 2 to 198 Hz.

After setting the center frequency fc,
Next, a pass band and an attenuation band before and after the cutoff frequency are determined. By setting the LPF as the attenuation band on the higher frequency side than the cutoff frequency and the HPF as the attenuation band on the lower frequency side than the cutoff frequency, it is possible to set a bandpass filter similar to the bandpass filter 9b described later.

On the other hand, the band filter setting unit 9
As shown in (b), it is composed of a transmission circuit 9a whose center frequency fc can be changed by a setting rotary code switch 9d, and a band-pass filter 9b (hereinafter referred to as "BPF"). When a bandpass filter is constituted by a BPF alone instead of a combination of an LPF and an HPF as shown in FIG. 3A, the bandwidth can be set in a plurality of stages by a rotary code switch 9c for setting a band frequency. FIG. 4 shows a frequency response performance curve when the frequency bandwidth is changed in nine steps using the BPF. The vertical axis in FIG. 4 is the gain, and the horizontal axis is the vibration frequency.

The electric signal passing through the band filter setting section 8 or the band filter setting section 9 is an acceleration signal, and is integrated by the integration circuit 10 and converted into a speed signal. The converted speed signal enters a comparison circuit 12 and is compared in magnitude with a voltage of a reference electric signal setting unit 11 for setting a voltage (−15 V to +15 V) which is an alarm reference value in advance. Only the upper limit value of the voltage is compared, but even if the voltage exceeds the upper limit value, it is conceivable that instantaneous values or temporarily large vibrations of peripheral devices are picked up as a signal.
2, a delay timer circuit 13 is connected.

The delay timer circuit 13 is a circuit for setting a delay time, and determines whether the signal exceeding the upper limit value in the comparison circuit 12 is finally "normal" or "abnormal". It can be determined by time. The delay time is set to 0 to 9 using the setting rotary code switch 13a.
Seconds can be set.

If the signal is finally judged as "abnormal" in the comparison circuit 12, the output signal of the comparison circuit 12 is transmitted to an alarm circuit (not shown). Output the signal.

As described above, by connecting the delay timer circuit 13 to the comparison circuit 12, it is possible to prevent a false alarm due to an instantaneous vibration change or disturbance.

According to the above-described configuration, (1) an electric signal output from a vibration detection sensor is generated by a band filter setting unit of a signal processing unit when a rotary device, a reciprocating device, and the like are operating normally. By providing a bandpass filter with the specific vibration frequency as the center frequency, only the vibration value near the vibration frequency of the device whose vibration is to be monitored can be monitored. As a result, false alarms due to vibrations from other external devices can be prevented. (2) Since only the frequency in a specific frequency band is analyzed without performing the waveform analysis of the amplitude and frequency of the whole vibration as in the related art, an expensive measuring instrument is not required. As a result, the vibration detection device is inexpensive, and can be used as an inexpensive machine vibration detection device. (3) By connecting a delay timer circuit to the comparison circuit so that the delay time can be set, it is possible to prevent a false alarm due to an instantaneous vibration change or disturbance.

[0020]

According to the vibration detecting device of the present invention described above, the following effects can be obtained. (1) The electric signal output from the vibration detection sensor is converted into a band-pass filter setting unit of the signal processing unit by using a unique vibration frequency generated when the rotating device or the reciprocating device or the like is operating normally as a center frequency. By providing the bandpass filter, it is possible to monitor only the vibration value near the vibration frequency of the device whose vibration is to be monitored. As a result, false alarms due to vibrations from other external devices can be prevented. (2) Since only the frequency in a specific frequency band is analyzed without performing the waveform analysis of the amplitude and frequency of the whole vibration as in the related art, an expensive measuring instrument is not required. As a result, the vibration detection device is inexpensive, and can be used as an inexpensive machine vibration detection device. (3) By connecting a delay timer circuit to the comparison circuit so that the delay time can be set, it is possible to prevent a false alarm due to an instantaneous vibration change or disturbance.

[Brief description of the drawings]

FIG. 1 is an external view of a vibration detection sensor according to the present invention.

FIG. 2 is a block diagram of a signal path of the vibration detection sensor according to the present invention.

FIG. 3 is a block diagram of a signal path of a signal processing unit of the vibration detection device according to the present invention.

FIG. 4 is a diagram showing a frequency response performance curve output when the frequency bandwidth is changed in nine steps using the band-pass filter of the vibration detection device according to the present invention.

FIG. 5 is an explanatory diagram of a conventional mechanical vibration detection device.

FIG. 6 is an explanatory diagram of a conventional electric vibration detection device.

[Explanation of symbols]

 Reference Signs List 1 box 2 cable folder 3 power plug 1a acceleration sensor 1b amplifier 1c low-pass filter 1d amplifier 4 box flange 5 hole 6 cable 7 output terminal 8,9 band filter setting section 8a, 8a 'transmission circuit 8b HPF (high-pass filter) 8c LPD (low-pass filter) 8d, 8d 'Rotary code switch for setting 9a Oscillator 9b BPF (bandpass filter) 9c Rotary code switch for setting band frequency 9d Rotary code switch for setting 10 Integrator circuit 11 Reference electric signal setting unit 12 Comparison circuit 13 Delay timer circuit 13a Rotary code switch for setting 14 Output circuit 15 Power supply A Vibration detection sensor B, B 'Band filter circuit fc Center frequency

Claims (3)

[Claims] 1. A vibration detection sensor that is attached to a casing of an apparatus and detects mechanical vibration and converts the vibration into an electric signal. After the electric signal output from the vibration detection sensor is amplified, the vibration detection sensor responds to mechanical vibration other than a target. A band-pass filter circuit that cuts an electric signal band to be processed, an integration circuit that calculates an acceleration of only a target electric signal band into a speed, and a comparison circuit that compares an output value of the integration circuit with a preset alarm reference value. An output circuit that closes (opens) an output contact when an output value of the comparison circuit is equal to or more than an alarm reference value. 2. The vibration detecting device according to claim 1, wherein a set value of the band filter circuit can change a center frequency and a bandwidth. 3. The vibration detection device according to claim 1, wherein the comparison circuit is capable of setting a delay time to prevent a false alarm due to an instantaneous vibration change or disturbance. apparatus.