JPH05231361A - Method and device for diagnosing oil-free screw compressor - Google Patents

Abstract

PURPOSE:To easily and quantitatively diagnose contact with the counter rotors of an oil-free screw compressor based on an AE wave and a rotational pulse. CONSTITUTION:An AE wave from a compressor 1 is detected by an AE sensor 2, detected to be amplified by a preamplifier 3 and a main amplifier 4 and frequency-analyzed and addition mean-processed by a processing device 6, to compare an AE voltage level, synchronized with a rotatioal pulse from a rotor rotational pulse detector 5 of this compressor, with the decision reference in an evaluation output device 7, and to perform a diagnosis output of such as whether rotor contact is provided or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-free screw compressor diagnostic method and apparatus for diagnosing whether or not a male rotor and a female rotor rotating inside a non-contact oil-free screw compressor are in contact with each other.

[0002]

2. Description of the Related Art A conventional method for diagnosing an oil-free screw compressor determines whether or not rotors of a screw compressor are in contact with each other based on the vibration value or noise value of the compressor during operation, or the shaft vibration value of the rotor, or It was usual to judge by the human sense of hearing with a sound stick. Related to this type of diagnostic method and apparatus is, for example, Japanese Laid-Open Patent Publication No. 58-143, which is used as bearing diagnostics for turbine rotors in power plants.
222 and JP-A-58-150859.

[0003]

In the above-mentioned prior art, when the vibration of the oil-free screw compressor or the shaft vibration of the rotor is detected and a certain level is exceeded, it is determined that the rotors are in contact with each other, or the sound-acquiring rod is used. Since the rotor contact was judged by the audible feeling, there was a problem that it was difficult to quantitatively evaluate the contact between the rotors.

An object of the present invention is to solve the above-mentioned problems of the prior art and to easily and quantitatively evaluate the contact between rotors during operation of the oil-free screw compressor, and to diagnose the oil-free screw compressor. And to provide the device.

[0005]

In order to achieve the above object, a method and apparatus for diagnosing an oil-free screw compressor according to the present invention includes a male rotor and a female rotor when a rotor of a non-contact oil-free screw compressor rotates. The AE wave generated by the contact and the rotor rotation signal at that time are detected,
The rotor contact is diagnosed based on the detected AE signal and rotation signal, and the AE signal is amplified and detected, and its output is subjected to frequency analysis and arithmetic averaging.
Compare the result with the criterion based on the rotation signal,
The diagnosis is made for the presence or absence of rotor contact.

[0006]

The above-described method and apparatus for diagnosing the oil-free screw compressor detects the AE (acoustic emission) wave generated when the rotors inside the non-contact oil-free screw compressor come into contact with each other by the AE sensor, and at the same time. The rotor rotation pulse signal is detected by the rotor rotation pulse detector, and the rotor contact pulse detector detects the AE signal and the rotation signal as input to diagnose the rotor contact. The AE signal is amplified and detected by an amplifier, and the amplifier is detected. The output is subjected to frequency analysis and addition and averaging processing by Fast Fourier Transform (FFT), and the component synchronized with the above rotation (rotation speed) signal is extracted from the processed value and compared with the judgment reference value inside the microcomputer. Whether the rotors are in contact with each other is determined based on the magnitude of and output.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an overall system configuration diagram showing an embodiment of an oil-free screw compressor diagnosis method and apparatus according to the present invention. In FIG. 1, 1 is a non-contact type oil-free compressor (main body), 2 is a compressor (main body) 1
An AE sensor for detecting the AE wave from 3 is a noise resistant preamplifier for amplifying its output, 4 is a wide band main amplifier for amplifying and detecting its output, and 5 is a sensor for detecting a rotation signal of a rotor in the compressor 1. A rotor rotation pulse (rotation speed) detector for converting and outputting to a rotation pulse, 6 inputs the output of the main amplifier 4 and analyzes two signals individually to perform a frequency analysis and an averaging process and a rotor rotation pulse. A frequency analysis and averaging processor (FFT analyzer) that inputs the output of the detector 5 and counts the number of rotation pulses to obtain the rotation frequency, and 7 is an output of the processor 6 for evaluating rotor contact in the compressor 1. And an evaluation and output device (rotational synchronization determination device) which generally comprises a computer, a display and a printer for outputting.

With the above structure, when the internal male rotor and the female rotor (not shown) come into contact with each other during operation of the non-contact type oil-free screw compressor (main body) 1, an AE wave is generated. ) Is transmitted from the compressor (main body) 1 to the AE sensor 2 and converted into an electric signal. The AE signal generated by the AE sensor 2 is amplified by the noise resistant preamplifier 3 and further amplified and detected by the wideband main amplifier 4. One rotor rotation pulse detector 5 is a compressor (main body)
The rotor rotation signal of No. 1 is detected and converted into a rotor rotation pulse (rotation pulse signal). Using the outputs of the main amplifier 4 and the rotor rotation pulse detector 5 as inputs, a frequency analysis and averaging processing device (FFT analyzer) 6 performs frequency analysis and averaging processing by FFT of the amplifier output and counts the number of rotation pulses. . The evaluation and output device (rotation synchronization determination device) 7 receives the output of the processing device 6 as an input, synthesizes the frequency analysis and addition and averaging process results of the AE signal and the count processing result of the rotation signal, and detects the rotor contact in the compressor 1. Evaluate and output the rotation synchronization frequency such as presence or absence.

FIG. 2 is an explanatory diagram showing the evaluation determination contents of the evaluation and output device (rotation synchronization determination device) 7 of FIG. In FIG. 2, the horizontal axis represents frequency (Hz) and the vertical axis represents processing device 6.
Shows the AE signal voltage (V) after the frequency analysis and the averaging process, and the horizontal axis also shows the rotor rotation frequency after the rotation pulse number is counted by the processing device 6. The evaluation and output device (rotation synchronization determination device) 7 is a male rotor obtained from the rotor rotation pulse and the frequency component of the AE signal voltage resulting from the frequency analysis and averaging of the AE signal from the compressor 1 of FIG. And the interrelationship with the rotation frequency of the female rotor are examined to obtain the rotation synchronization voltage level synchronized with the rotation pulse of the AE signal. Further, when the rotors contact each other once for rotation and rotate, an AE signal synchronized with the primary of the rotation pulse is generated, and the AE signal voltage of FIG. When a component is generated, and when the contact is made twice for one rotation, an AE signal synchronized with the secondary of the rotation pulse is generated, and a component of the rotation secondary synchronization frequency is generated in the AE signal voltage of FIG. Therefore, the presence or absence of rotor contact is determined by comparing the rotation synchronization voltage level of the AE signal voltage in FIG. 2 with a predetermined determination criterion (threshold value) or a determination criterion (threshold value) determined for each frequency component. Then, the judgment result is output. Further, it is possible to determine the degree of rotor contact based on the magnitude of the rotation synchronization voltage level, and determine the form of rotor contact based on the frequency component of the rotation synchronization order of the AE signal voltage, and output the result.

[0010]

According to the present invention, from the AE signal and the rotor rotation signal during the operation of the non-contact type oil-free compressor,
By examining the voltage level of the rotational synchronization order of the AE signal, it is possible to evaluate whether or not the rotors are in contact with each other, the degree, the form, etc., and to easily perform a quantitative diagnostic test. In addition, by miniaturizing this diagnostic device and mounting it on an oil-free compressor product, it is possible to detect contact between rotors early and prevent accidents due to rotor contact.

[Brief description of drawings]

FIG. 1 is an overall system configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the evaluation determination content of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor (main body), 2 ... AE sensor, 3 ... Noise-resistant preamplifier, 4 ... Wideband main amplifier, 5 ... Rotor rotation pulse detector, 6 ... Frequency analysis and averaging processing device, 7 ... Evaluation and output device (Rotation synchronization determination device)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kaya Sato 1168 Moriyama-cho, Hitachi City, Ibaraki Prefecture, Hitachi Energy Research Institute Co., Ltd. (72) Inventor Minoru Yanagibashi 3-2-2 Sachimachi, Hitachi City, Ibaraki Hitachi Engineering Service Co., Ltd.

Claims (3)

[Claims] 1. An AE wave generated by contact between a male rotor and a female rotor during rotation of a rotor of a non-contact type oil-free screw compressor and a rotation signal of the rotor at that time are detected, and the detected AE signal and rotation signal are detected. A method for diagnosing an oil-free screw compressor, which comprises diagnosing rotor contact based on the method. 2. Amplifying and detecting the AE signal, subjecting the output to frequency analysis and averaging processing, and comparing the result with a determination standard based on the rotation signal to diagnose the presence or absence of rotor contact. The method for diagnosing an oil-free screw compressor according to claim 1. 3. An AE sensor for detecting an AE wave generated by contact between a male rotor and a female rotor during rotation of a rotor of a non-contact type oil-free screw compressor, and the detected AE sensor.
An amplifier for amplifying and detecting a signal, a device for performing frequency analysis and an averaging process on the output of the amplifier, a rotor rotation pulse detector for detecting a rotation signal of the rotor and converting it into a rotation pulse, and a rotation result for the processing result. A diagnostic device for an oil-free screw compressor, comprising: a device that evaluates and outputs the presence or absence of rotor contact based on a signal in comparison with a determination standard.