JPH06300826A - Motor inspecting apparatus - Google Patents

Abstract

PURPOSE:To obtain a motor inspecting apparatus so designed as to make it possible to determine the quality of the motor on the basis of noise objectively and automatically at all times and to attain the determination of the quality and classification of a cause of abnormality highly accurately and mechanically. CONSTITUTION:A computer 14 having functions of retrieving and extracting a pertinent cause from an abnormality cause classification table 24 on the basis of a processing of comparison of representative values 16 and 18 stored beforehand with input values 15 and 17 and the results thereof is provided, and the vibration generated from a motor 10 to be tested which is operated under the control by an operation control device 26 is analyzed, being sorted into three kinds of states, a starting state, a state of steady-state operation and a state of stoppage (state of inertial rotation). Accordingly, determination of the quality of the motor and classification of the cause of abnormality are executed automatically on the basis of the vibration of the motor, and therefore inspection of high precision can be conducted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus for determining the quality of an electric motor to be inspected by analyzing the amount of state such as vibration noise generated by the electric motor, and particularly suitable for inspection of an induction motor. Regarding inspection equipment.

[0002]

2. Description of the Related Art Generally, in any motor (electric motor), efforts are being made to minimize the generation of noise (vibration) during operation at the stage of designing and manufacturing the motor, and therefore, there is nothing to manufacture. As long as there is no problem, the noise should be suppressed to a predetermined level or less when it is completed as a product, and the frequency distribution of noise should also be maintained in the predetermined state.

Therefore, an inspection method is conventionally known in which the noise of the motor is detected and the quality of the motor is judged from the state of the noise.
This will be described with reference to FIG.

In the prior art shown in FIG. 2, reference numeral 1 denotes a motor to be inspected, such as a general-purpose induction motor, which is installed on a predetermined inspection table and is supplied with electric power from a control device (not shown). It is supplied and operated. A vibration sensor (acceleration pickup) 2 is attached to the motor 1 by a magnet or the like.

Then, while the motor 1 is rotating, the vibration signal detected by the vibration sensor 2 is amplified by the preamplifier 3 and the speaker amplifier 4, converted into a sound by the speaker 5, and the inspector 6 hears the sound. , The distinction between good and bad products of the motor 1 and the cause of the abnormality were classified according to the sense of hearing.

In addition to this, or in combination with this, the vibration signal from the preamplifier 3 is frequency-analyzed by the frequency analyzer 7, and the frequency analysis result 8 is obtained by the inspector 6 as a motor which is a non-defective motor. By comparing with the frequency analysis result 9 according to the above, the cause of abnormality was discriminated from the non-defective / defective product by observation.

[0007]

The prior art has a problem that the objectivity of the inspection result is not sufficiently considered and the reliability is poor. In other words, in the prior art, the determination as to whether the motor is a good product or a defective product and the classification of the abnormal cause of the motor when it is determined as a defective product rely on the sensory judgment of the inspector. There are variations in judgment results due to differences in personnel, differences in results of categorization of abnormal causes, etc. Therefore, sufficient reliability cannot be obtained and highly accurate inspection cannot be expected.

An object of the present invention is to always objectively and automatically determine whether a motor is good or bad by noise or vibration without relying on human sensory judgment. An object is to provide a motor inspection device that can be mechanically obtained with high accuracy.

[0009]

In order to achieve the above object, an operation control means for controlling a motor to be inspected to a predetermined operation state such as a starting state, a rated operation state and a coasting rotation state, and a sensor means. The analysis of the detected operation state quantity is executed in the above-mentioned predetermined operation state, and an analysis processing means for giving an analysis result and an analysis result by this analysis processing means are compared with respective preset reference analysis results to determine an abnormality. And a cause search processing means for comparing the three types of abnormality determination results obtained by the comparison processing means with preset abnormality cause type classification results and making a pass / fail determination. Here, each of the above-mentioned means is generally composed of a computer that operates according to a predetermined program.

[0010]

The state quantity generated at the start of the motor to be inspected and at the time of the rated operation, the inertial rotation and the like is detected by the sensor means, and the result detected by the sensor means is compared with the comparison processing means. Is compared with the reference analysis result to determine an abnormality, and this result is determined by comparing with the abnormality cause classification result, so that the determination process can be given as a calculation result, and an objective determination can be made automatically. can get.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A motor inspection device according to the present invention will be described in detail below with reference to the illustrated embodiments. FIG. 1 shows an embodiment of the present invention, in which a motor 1 to be tested (inspected) and a vibration sensor (acceleration pickup) 2 attached to the motor 1 by a magnet or the like are the same as those in the prior art. In FIG. 1, 12 is an amplifier (amplifier) and 13 is an analyzer. This analyzer 13 frequency-analyzes a signal (vibration signal) from the vibration sensor 2 input via the amplifier 12, and It works to convert to overall amplitude value.

Reference numeral 14 denotes a computer, which includes an arithmetic processing unit (not shown) and various storage devices (ROM, RAM, etc.), and is provided with a predetermined program, whereby a data comparison processing function 19 is provided. , 20 and a function 23 for performing a process of searching for a cause of abnormality from the comparison result after the comparison process.

Reference numeral 26 denotes an operation control device, which is a motor 1 under test.
It has a function of performing control such as starting, running, and stopping, and is interfaced with the computer 14 by means not shown. The computer 1
Other elements in 4 will be described in order.

Next, the operation of this embodiment will be described. After the motor under test 1 is set on a predetermined inspection table and the vibration sensor 2 is attached as shown in the figure, the motor under test 1 is started by the operation control device 26 and is operated for a predetermined time. After being brought to a steady operation state, the operation is controlled to a stop state. Here, the stopped state or the stop does not mean a state in which the motor under test 1 stops rotating, but the supply of electric power from the operation control device 26 to the motor under test 1 is stopped, and the motor under test 1 is stopped. The state in which the motor 1 is in the inertial rotation state (free running state) from the steady operation state until the rotation is stopped.

At this time, the vibration generated in the motor under test 1 is detected by the vibration sensor 2 and becomes a vibration signal, which is input to the analyzer 13 via the preamplifier 12,
At the time of start-up, at the time of steady operation and at the time of inertia rotation, they are respectively converted into the frequency analysis input value 15 and the overall input value 17 and input to the computer 14 and stored in a predetermined buffer (RAM). To be done.

On the other hand, at this time, whether the three types of vibration data input to the computer 14 are data at the time of starting, operating, or stopping is determined by the computer from the operation control device 26 via the above-mentioned interface. 14 are recognized at the same time.

FIG. 3 shows an example of the frequency analysis input value 15 and the overall input value 17 detected from the motor 1 under test at this time. And, with this overall input value 17, it is about 0.6 from the time 0.0 (second).
The period up to (sec) is the starting time, the period up to about 4.5 (sec) thereafter is the steady operation, and the period thereafter is the inertia rotation.

In the storage device of the computer 14, representative values (an average vibration frequency analysis value and an overall value in a non-defective motor) when the motor 1 is started, in operation, and when stopped are standardized in advance. The representative values 16 and 18 stored as the analysis result and the input values 15 and 17 stored in the buffer are compared processing function 1
9 and 20 are compared to determine whether or not there is an abnormal value for each operating state. The representative values 16 and 18 are prepared for each model of the motor under test 1 and are selected according to the model of the motor under test 1.

Therefore, the computer 14 uses the input value 1
The processing by the comparison processing functions 19 and 20 is started at a predetermined timing after the storage of the buffers 5 and 17 is completed.

First, in the comparison processing function 19, the frequency analysis input value 15 is compared with the representative value 16, and if there is a frequency in which the level between them exceeds a predetermined value and causes a difference, it is determined that there is an abnormality, and The frequency indicating the abnormal value is obtained, and stored as a comparison result 21 in a predetermined buffer together with the operating state at that time. On the other hand, if there is no difference in the level exceeding the predetermined value, no abnormal value (OK) is stored.

Similarly, in the comparison processing function 20, the overall input value 17 is compared with the representative value 18, and if there is a difference between these levels exceeding a predetermined value, it is determined that there is an abnormality, and that level is determined to be abnormal. The comparison result 22 is stored in a predetermined buffer together with the operating state. On the other hand, if there is no difference in the level exceeding the predetermined value, no abnormal value (OK) is stored.

Here, the overall value will be described. This is the maximum value (level) at each frequency within the range of the noise (vibration) measurement frequency calculated by the following (Equation 1) formula. is there.

[0023]

[Equation 1]

As an example, when a 1/3 octave analyzer is used as the analyzer 13 and the center frequency is measured from 31.5 Hz to 10,000 Hz, the sound pressure level x ₀
The center frequencies of ˜x _n are as shown in (Table 1).

[0025]

[Table 1]

Therefore, the overall value can be obtained by substituting the values of these sound pressure levels x _{0 to} x _{n into} the equation (1).

Next, the computer 14 starts the processing by the cause search processing function 23 at a predetermined timing after the comparison results 21 and 22 are stored in a predetermined buffer.

The processing by the cause search processing function 23 is
Abnormal cause classification table 2 based on the comparison results 21 and 23
4 is a process for extracting the cause corresponding to the abnormality, and the abnormality cause classification table 24 used here is prepared in advance for each motor type (A), (B), (C), ... It is a table in which abnormal frequencies, ... The table 24 can be obtained by calculation in advance or by accumulating data actually collected from the motor.

For example, when the motor 1 is an induction motor,
The fundamental frequency of the electromagnetic vibration in that is obtained by Formula 1.

[0030]

[Equation 2]

Therefore, in steady operation, when the values at these frequencies exceed the typical values and are judged to be abnormal, while on the other hand, when they are judged to be normal at stop (during free run), the cause is electromagnetic vibration. It can be said that it is necessary to investigate the air gap or slot relation of the motor as a result.

Further, by calculating the natural frequency of each part of the motor and grasping the relationship between each natural frequency and the fundamental frequency obtained by the formula 1, the operating state when an abnormal value occurs Alternatively, the frequency at which the abnormal value is generated can be classified as the cause of the resonance of the component caused by the electromagnetic vibration, which is the fundamental frequency of the equation 2.

Of the mechanical vibrations, regarding the vibration of the bearing of the motor, the natural frequency in the axial direction will be described as an example.

[0034]

[Equation 3]

When there is an abnormality in the bearing, even when the motor power is cut off (free running state), vibrations due to the abnormality always occur during rotation, so the value at the frequency obtained from Equation 3 is obtained. If the abnormality is judged to exceed the representative value both during operation and during stop (during free run), it can be easily classified that the cause is the bearing.

FIG. 4 shows the vibration frequency analysis result of the motor, and the frequency analysis result 27 in the normal motor is shown.
And the frequency analysis result 28 of the motor having an abnormality in the bearing, it can be seen that there is a difference in the value between 2 kHz and 20 kHz.

Although the analysis result of FIG. 4 shows a case where a significant difference is found between the normal motor and the abnormal motor, according to this embodiment, a slight difference or a specific frequency is detected. Even when an abnormal value occurs, the difference can be accurately detected, and the cause of the abnormality can be automatically classified.

In this way, when the processing by the cause search processing function 23 is completed and a result is obtained, the computer 14 performs the display processing of the result display 25 at the timing after that point. As the display processing, screen display processing and printout processing can be considered, but either one may be selected and, of course, they may be used in combination.

Therefore, according to this embodiment, the motor 1 to be tested is placed on the test stand, the vibration sensor 2 is attached, and then the operation control device 26 is instructed to start the inspection. Since the inspection process is executed and the results are displayed, it is possible to obtain inspection results based on sufficiently objective criteria, which is completely different from the sensory judgment results by the tester. It can be done easily.

In the above embodiment, the vibration sensor 2 is used to detect the vibration of the motor under test 1, but a microphone is used instead of the vibration sensor 2 to emit the motor under test 1. Noise may be detected and input to the amplifier 12.

In the above, the vibration and noise are detected and analyzed, and the cause of the abnormality is categorized. However, if the state quantity changes depending on the cause of the abnormality, not limited to the vibration and noise, this state Quantities can be detected and analyzed, as well as causal categorization.

[0042]

According to the present invention, the measurement of the state quantity generated corresponding to the rotation state of the motor, the comparison of the result with the representative value, and the determination of the cause classification based on the comparison result are all mechanized. Since it is processed in the above manner, there is no fear of the variation of the quality judgment due to the difference of the inspector and the difference of the classified result of the cause of the abnormality, so that the inspection accuracy and the reliability can be greatly improved. Further, according to the present invention, since the inspection of the motor is automated, it becomes possible to perform the in-line inspection in the production line of a general-purpose induction motor or the like, which greatly contributes to the quality improvement and the cost reduction.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of an electric motor inspection device according to the present invention.

FIG. 2 is an explanatory diagram showing a conventional example of an inspection method by vibration of an electric motor.

FIG. 3 is a characteristic diagram showing an example of a frequency analysis input value and an overall input value according to an embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a difference in a frequency analysis input value according to an embodiment of the present invention.

[Explanation of symbols]

 1 Motor under test 2 Vibration sensor (acceleration pickup) 12 Preamplifier 13 Analyzer 14 Computer 15 Input value of frequency analysis value 16 Representative value of frequency analysis value 17 Input value of overall value 18 Representative value of overall value 19 Comparison of frequency analysis value Processing function 20 Overall value comparison processing function 21 Frequency analysis value comparison result 22 Overall value comparison result 23 Cause search processing function 24 Model-specific error cause classification table 25 Result display 26 Operation control device 27 Normal motor vibration frequency analysis result 28 Vibration frequency analysis result of bearing abnormal motor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigeru Nomoto, 7-1, 1-1 Higashi Narashino, Narashino, Chiba, Chiba Prefecture Inside the Hitachi Narashino Factory (72) Inventor Hideo Tada, 7-1, Higashi Narashino, Narashino, Chiba Hitachi Ltd. Narashino Plant (72) Inventor Masao Taniguchi 7-1, Higashi Narashino, Narashino City, Chiba Prefecture Hitachi Ltd. Narashino Plant

Claims (3)

[Claims] 1. A sensor means for detecting a state quantity generated corresponding to a rotation state of an electric motor to be inspected, and a quality judgment of the electric motor to be inspected based on an analysis result of the state quantity detected by the sensor means. In the electric motor inspection device of the method, the operation control means for controlling the electric motor to be inspected to a predetermined operation state and the analysis result of the state quantity are compared with a preset reference analysis result to make an abnormality determination. A processing means and a cause search processing means for performing a pass / fail judgment by comparing the abnormality determination result by the comparison processing means with a preset abnormality cause classification result are provided. An inspection device for an electric motor, characterized in that it is configured to automatically give a pass / fail judgment result. 2. An inspection device for an electric motor, comprising: a sensor means for detecting vibration of the electric motor to be inspected; and a device for judging whether the electric motor to be inspected is good or bad based on an analysis result of the vibration detected by the sensor means. The operation control means for controlling the target electric motor to the starting state, the rated operating state and the inertial rotation state, and the analysis of the vibration detected by the sensor means, at each time point at the starting, rated operation and inertial rotation of the inspection target electric motor. And an analysis processing means for executing three kinds of analysis results to give three kinds of analysis results, and a comparison processing means for comparing the three kinds of analysis results by the analysis processing means with respective preset standard analysis results to make an abnormality determination. The cause search processing means is provided which compares the three types of abnormality determination results by the comparison processing means with the preset abnormality cause type classification results and executes the quality determination. An inspection apparatus for an electric motor, characterized in that the cause search processing means is configured to automatically give a quality judgment result of the inspection target electric motor. 3. The invention according to claim 2, wherein the three types of analysis results by the analysis processing means are provided as analysis results of both the frequency distribution state and the amplitude value of the vibration, respectively. Characteristic electric motor inspection device.