JP2003174751A - Electric motor - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide an electric motor capable of improving reliability against high heat, vibration shock, noise, and the like, and being usable up to high-speed rotation. SOLUTION: A bracket 4 on a detector 2 side of an electric or magnetic means is made of a magnetic material, and at least a detector 2 side of a rotating shaft 5 is made of a non-magnetic material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improving the reliability of an electric motor equipped with a detector.

[0002]

2. Description of the Related Art In recent years, robots as industrial equipment, N
C machine tools, semiconductor manufacturing equipment, etc.
With higher performance, the same demands are being made for electric motors (servo motors) mounted as drive sources.

In order to improve the portability of equipment and save energy and resources, electric motors are required to be downsized.
Higher speed is in progress to improve the tact of equipment,
Electric motors are required to achieve even higher speeds.

However, with the downsizing and higher performance of electric motors, high reliability is required for the electric motor and the detector mounted therein.

In order to deal with these problems, a conventional electric motor is
A means for performing control using an optical rotary encoder as a detector is generally used.

[0006]

However, the conventional optical encoder has a problem in terms of reliability in a high temperature range and reliability with respect to impact resistance.

Specifically, there is a possibility that the bearing grease may vaporize under high temperature and high speed rotation and adhere to the optical component, resulting in erroneous detection.

Further, a detector using an electric or magnetic means as a control detector is easily affected by the magnetic field of the electric motor main body, and there is a possibility that noise may be added to the detection signal to cause erroneous detection.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a motor capable of improving reliability against high heat, vibration shock, noise, and the like, and being usable up to high speed rotation.

[0010]

In order to solve the above problems, an electric motor according to the present invention includes a stator having a winding, a rotor having a magnet rotor and a rotary shaft, and a bearing rotatably via a bearing. A bracket that supports the rotor and a detector that is provided outside the bracket and that uses electrical or magnetic means are provided, and the bracket on the detector side is made of a magnetic material, and at least the detector side of the rotating shaft is It is composed of a non-magnetic material.

[0011]

In order to solve the above-mentioned problems, an electric motor according to a first aspect of the present invention includes a stator having a winding, a rotor having a magnet rotor and a rotary shaft, and a bearing so that the motor can rotate freely. A bracket that supports the rotor and a detector that is provided outside the bracket and that uses electrical or magnetic means are provided, and the bracket on the detector side is made of a magnetic material, and at least the detector side of the rotating shaft is provided. It is composed of a non-magnetic material, and a part of the rotating magnetic field generated by energizing the stator winding is leaked to the detector side. It is something to lose. Further, since at least the detector side of the rotating shaft is made of a non-magnetic material, the magnetic flux of the rotor magnet does not affect the detector through the rotating shaft.

Further, in the electric motor according to the present invention, the detector side bracket is provided with a hole for a lead wire for supplying electric power to the stator winding and a partition wall made of a magnetic material between the hole and the detector. Since the radiation noise generated by passing the switching current through the stator winding is shielded by the partition wall, the detector can be protected from the radiation noise.

[0013]

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

(Embodiment 1) In FIG. 1, 1 is an electric motor,
Reference numeral 2 is a detector, 3 is a stator having windings, 4 is a bracket on the detector side, and 5 is a rotating shaft of a magnet rotor.

The detector 2 is a brushless resolver that converts the rotor angular position into an electric signal by electromagnetic induction, and is composed of a stator section, a rotor section, and a rotary transformer section.

For example, a brushless resolver with two-phase input and one-phase output is composed of two stator windings with a stator portion spatially displaced by 90 °, and a rotary transformer portion is composed of a transformer fixed winding and a rotary winding. There is. The rotating winding and the winding of the rotor portion are connected to each other to form a closed loop and are fixed to the rotating shaft 5. In addition, the stator and transformer fixed winding are
It is centered on the basis of and is fixed to the bracket 4.

When a switching current is passed through the winding of the stator 3 to create a rotating magnetic field, a part of the magnetic flux is detected by the detector 2.
Try to leak to the side.

However, since the bracket 4 on the detector 2 side is made of a magnetic material, it exerts the action of a forced magnetic path and electromagnetic shielding. As a result, it is possible to prevent magnetic leakage and radiant noise from entering the detector 2.

The rotary shaft 5 is formed by pressure contact with the magnet rotor side being a magnetic material and the detector side being a non-magnetic material 5a, and the magnetic flux of the rotor magnet is passed through the rotary shaft 5 to the detector 2 side. It does not leak and does not adversely affect the signal detected by the detector 2. Further, in the case of a magnet rotor having an inner yoke, the entire rotary shaft 5 may be made of a non-magnetic material without being pressed against it.

As described above, by making the bracket on the detector side magnetic, it is possible to prevent the leakage flux of the rotating magnetic field from the stator winding from adversely affecting the resolver winding.

The brushless resolver is more resistant to heat and vibration impact than the optical encoder and does not use optical parts even if the grease vaporizes at high temperature and high speed rotation.
It can be used up to high speed without being affected by it.

The resolver as a detector can be replaced with a magnetic encoder, and the same effect can be obtained.

(Embodiment 2) The embodiment 2 protects the detector from the influence of the lead wire for supplying electric power to the stator winding. The difference from the embodiment 1 is the lead wire lead-out structure, and the same reference numeral is used. Will be explained.

In FIG. 2, a bracket 4 on the detector side is provided with a hole 4a for drawing out the lead wire 6 and a partition wall 4b made of a magnetic material between the hole 4a and the detector 2.

The partition wall 4b may be integrally formed with the magnetic bracket 4 or may be a separate body and fixed with a screw.

Since a shield line is generally used for the signal line of the detector 2, it is only necessary to prevent noise from directly entering the signal detection source. Therefore, the hole 4a of the magnetic bracket 4 and the partition wall. The leads are isolated from the detector by 4b.

Thus, radiation noise generated by supplying power to the stator winding can be shielded, and it is possible to prevent the noise from jumping into the detector 2.

[0028]

As is apparent from the above-described embodiment, according to the invention of claim 1, since it is equipped with an electrical or magnetic detector, it is resistant to heat and vibration impact and can be used up to high speed rotation. Moreover, the electric motor is highly reliable and is not easily affected by the leakage magnetic flux.

According to the second aspect of the invention, the radiation noise generated from the lead wire for supplying power to the detector stator winding can be shielded by the partition wall to prevent the noise from directly entering the detector.

As described above, since no optical parts are used, it is resistant to heat and vibration shock, and can be used even at high speeds. By effectively combining magnetic and non-magnetic parts, it is highly reliable against noise. An electric motor with a detector is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an electric motor according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an electric motor according to a second embodiment of the present invention.

[Explanation of symbols]

1 electric motor 2 Detector (resolver) 3 stator 4 bracket 4a hole 4b partition 5 rotation axes 5a Non-magnetic material (rotating shaft on the detector side) 6 lead wire

Claims (2)

[Claims] 1. A stator having a winding, a rotor having a magnet rotor and a rotating shaft, a bracket for rotatably supporting the rotor via a bearing, and an electric or magnetic rotor provided outside the bracket. An electric motor comprising: a detector using a mechanical means, wherein the detector-side bracket is made of a magnetic material, and at least the detector side of the rotating shaft is made of a non-magnetic material. 2. The electric motor according to claim 1, wherein the detector-side bracket is provided with a hole for a lead wire for supplying electric power to the stator winding, and a magnetic partition wall between the hole and the periphery of the hole.