JP2003284296A - Method and apparatus for inspecting magnetization in enclosed compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compressor in which a permanent-magnet motor is incorporated and magnetized, wherein the magnetization rate is judged by grasp ing the number of revolutions in finished product inspection, in which external driving is difficult, and the designed performance is delivered to the full, and thereby solve a problem that it is difficult to grasp the number of revolutions in the process of finished product inspection and thus the magnetization rate is difficult to measure. <P>SOLUTION: In complete examination, power is externally applied and then the power application is interrupted. The waveform of induced voltage produced immediately thereafter is measured. The number of revolutions and the root- mean-square value are determined from the measured waveform, and the magnetization rate is thereby determined. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetization inspection method for a hermetic compressor using an electric motor having a permanent magnet, which is used in refrigeration and air conditioning equipment and the like, and a magnetization inspection device used therefor.

[0002]

2. Description of the Related Art A stator which generates a rotating magnetic field by energizing a coil mounted on a stator core made of a magnetic material, and a rotor which is rotatably arranged in the stator and has a permanent magnet arranged therein. A permanent magnet electric motor including a child has been well known in the past, and is often used as an electric motor of a compressor for an air conditioner from the viewpoint of energy saving. When the rotor is fitted into the stator when assembling such a permanent magnet motor, if the permanent magnet of the rotor is magnetized,
Due to the strong magnetic force, the rotor may be attracted to the inner circumference of the stator and fixed immovably, which makes it difficult to insert the rotor into the stator. For this reason, the so-called built-in magnetizing method is generally used in which the rotor is fitted into the stator in a state where the magnet is not magnetized, and then the magnetizing current is applied to the coil of the stator to magnetize the magnet. Has been adopted.

Whether or not the magnetization is good, that is, the magnetization rate affects the efficiency of the electric motor and naturally has a great influence on the efficiency of the compressor. Therefore, in order to ensure the high performance of the compressor, the permanent magnet of the electric motor is used. It is necessary to ensure that the magnet is fully magnetized. Therefore, it is necessary to inspect whether the permanent magnet is sufficiently magnetized after the magnetizing step. In the inspection immediately after magnetization, the electric motor is not yet sealed in the container, so the induced voltage generated by mechanically driving the rotor from the outside and rotating it at a constant speed is measured, and the induced voltage The effective value can be calculated from the waveform, and the magnetization ratio can be calculated by comparing with the effective value of the induced voltage in the 100% magnetized rotor, which is the reference, to determine whether the magnetization is good or bad.

However, when the compressor is a finished product, since it is a hermetically sealed type, it is impossible to rotate the rotor at a constant rotational speed by external mechanical driving, so that it is difficult to judge the quality based on the magnetization rate. is there. Therefore, an electric power is applied from the outside to rotate the electric motor, the induced voltage is measured immediately after the electric power is cut off, the peak value is extracted, and the magnetization rate is determined from the tendency. Further, conventionally, the peak value on the plus side and the peak value on the minus side are measured and judged, but the height (induced voltage) is already different between the first wave and the second wave, and thus accuracy is lacking.

Recently, rare earth magnets are sometimes used from the viewpoint of high efficiency, and their magnet characteristics demagnetize at high temperatures. Therefore, the final magnetization rate determination in the compressor manufacturing process after built-in magnetization is performed. Inspection is an important factor in ensuring product performance.

[0006]

However, in the above-mentioned conventional inspection method, since the number of rotations is not known, the magnetizability is not obtained, and it is difficult to guarantee the final magnetizability as a finished compressor product. The present invention solves such a conventional problem, and realizes the guarantee of the magnetization rate in a finished product of a high-performance compressor driven by a permanent magnet type electric motor, and provides a stable and high-performance compressor. The purpose is to do.

[0007]

In order to solve the above-mentioned problems, the present invention finds the rotation speed and the effective value of the induced voltage from the waveform of the induced voltage generated immediately after the power is cut off after the power is applied from the outside. By doing so, the magnetization rate of the permanent magnet in the rotor is measured. By measuring the magnetic susceptibility by the method as described above, it is possible to measure the magnetic susceptibility in the finished compressor product after undergoing various steps after built-in magnetization.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, a permanent magnet in a rotor is obtained by determining the rotation speed and the effective value of the induced voltage from the waveform of the induced voltage generated immediately after the power is applied from the outside in the finished product and immediately thereafter. This is to calculate the magnetizing rate of the magnet. In this way, since the magnetization rate of the finished product can be measured, it is possible to detect the presence or absence of irreversible demagnetization due to the thermal influence in various assembly steps after the built-in magnetization.

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a measurement waveform of an induced voltage in one embodiment of the present invention. The vertical axis represents the induced voltage and the horizontal axis represents time. Reference numeral 1 is a period during which power is supplied, 2 is a time point when the power is cut off, and 3 is a period during which the motor rotates by inertia. It can be seen that the motor is stably rotating in the period of 1 and the electric power is cut off at the time of 2, so that in the period of 3 the rotation speed decreases as time passes and the induced voltage also decreases accordingly. . At this time, since the magnitude of the induced voltage is proportional to the magnetic flux density and the rotation speed of the motor, the effective value and the rotation speed are measured in advance from the induced voltage waveform after the power is cut off by the reference compressor, and the ratio is calculated. Every time, it is possible to judge the quality of magnetization by comparing it with that of the compressor to be measured.

In the normally rotated compressor, the waveform rotating by inertia maintains axial symmetry up to the fourth waveform with the peaks or troughs of the waveform as the axis, and up to the eighth waveform. It has been confirmed by the inventors' experiments that the high axial symmetry is maintained. Therefore, by grasping the tendency of the decrease in the symmetry of the waveform, it is possible to detect a compressor whose rotation is heavy. Further, conventionally, the peak value on the plus side and the peak value on the minus side are measured and judged, but the height (induced voltage) is already different between the first wave and the second wave, and thus accuracy is lacking.

FIG. 2 shows the first one of the induced voltage waveforms immediately after the power is cut off. In this range, the decay of the rotational speed is negligible as described above, that is, the range where the symmetry of the waveform is maintained. The magnetization rate in the finished product can be measured by obtaining the rotation speed and the effective value from the waveform. Further, if the temperature is measured at this time, the magnetization rate can be determined by correcting the demagnetization due to the temperature.

(Second Embodiment) FIG. 3 is an outline of an inspection apparatus according to an embodiment of the present invention. Reference numeral 5 denotes a drive inverter as a power supply device of the compressor, which has a built-in energization control means for intermittently controlling energization. 6 is a digital multimeter for finding the period and effective value of the induced voltage,
7 is the finished product of the compressor. After driving the finished compressor 7 with a constant rotation speed by the drive inverter 5, the drive inverter 5 is cut off, and only the first waveform is extracted from the waveform of the induced voltage measured by the digital multimeter 6 and rotated from the waveform. It is a device that measures the magnetic susceptibility by calculating the number and the effective value of the induced voltage. Further, by measuring the temperature of the compressor to be inspected, it is possible to correct the demagnetization due to the temperature and determine the magnetization rate.

[0014]

As is apparent from the above description, according to the invention of the present application, in the finished product of the compressor, the induced voltage after the drive power is cut off is measured, and the rotation speed and the effective value are obtained from the waveform, so that the finished product can Since the magnetic susceptibility can be accurately obtained, it is possible to guarantee the performance of the permanent magnet electric motor which is built in and magnetized through the manufacturing process of the compressor.

[Brief description of drawings]

FIG. 1 is a diagram showing an induced voltage waveform according to an embodiment of the present invention.

FIG. 2 is a diagram showing a first induced voltage waveform after power-off in the embodiment of the present invention.

FIG. 3 is a configuration diagram of an inspection device according to an embodiment of the present invention.

FIG. 4 is a diagram showing a conventional induced voltage determination method.

[Explanation of symbols]

1 power supply period 2 When power is cut off 3 Rotating by inertia 4 Time between points where the induced voltage of 0 V intersects the axis 5 drive inverter 6 Digital multimeter 7 Compressed product 8 Peak-to-peak measurement position of induced voltage

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2G016 BA03 BD06                 2G017 CA08                 5H621 BB07 GA01 GA04 HH01 JK13                 5H622 AA04 CA02 CA10 CB05 QB01

Claims (3)

[Claims] 1. A method for inspecting magnetization of a hermetic compressor, wherein a hermetically-sealed container contains a compression mechanism and an electric motor for driving the same, and the electric motor comprises a rotor having a permanent magnet and a stator to which a coil is mounted. A first step of energizing the coil to rotate the electric motor; a second step of measuring the period and the effective value of the induced voltage waveform generated in the coil after the energization of the coil is cut off; A method for inspecting magnetization of a hermetic compressor, comprising: a third step of comparing the period and the execution value of the induced voltage waveform with a reference value. 2. The method for inspecting the magnetization of a hermetic compressor according to claim 1, wherein the period and the effective value are measured for at least the same number of induced voltage waveforms as the number of magnetic poles of the rotor in the second step. A method for inspecting the magnetization of a hermetic compressor. 3. A magnetization inspection device for a hermetic compressor driven by an electric motor having a permanent magnet, wherein a power supply device for supplying a current for driving the electric motor and a current for the power supply device are intermittently controlled. An energization control unit, a measurement unit that measures the period and the effective value of the voltage waveform induced in the power supply terminal of the electric motor for a predetermined period after the current from the power supply device is cut off by the energization control unit, and the measured voltage. A magnetization inspection device for a hermetic compressor, comprising: a determination unit that compares a waveform period and an execution value with a reference value to determine whether the magnetization is good or bad.