JPS61272613A - Magnetic rotary encoder - Google Patents

Abstract

PURPOSE:To obtain a high-precision, high resolution magnetic rotary encoder by providing a fixed and a rotary part to a bearing itself which determines the center of rotation of a servo-motor and increasing the concentricity between the rotary part and fixed part. CONSTITUTION:The stator housing 11 of the servo-motor holds plural discoid stator cores 12, which have a laminate structure of stator elements equipped with a spiral winding element. One of a couple of bearings 14 and 15, i.e. 14 which support a rotor shaft 13 on the housing 11 rotatably is a roller bearing and the other 14 is a cross roller bearing; and plural discoid rotors 16 arranged between discoid stator cores 12 are fixed to the rotor shaft 13 and each rotor 16 is equipped with plural permanent magnets 16b put in a nonmagnetic base 16a at circumferential intervals. The external ring 17 of the bearing 15 is fixed to the housing 11 and the internal ring 18 is fixed to the rotor shaft 13; and the ring-shaped fixed part 20 of the magnetic rotary encoder 19 is fixed to the external ring 17 and the ring-shaped rotary part 21 of the encoder 19 is fixed to the internal ring 18 coaxially.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotary encoder, and more particularly to a magnetic rotary encoder for detecting the rotational position and speed of a servo motor.

[Prior art and its problems]

BACKGROUND ART In recent years, as motors have become smaller and more precise, there has been a demand for low-return encoders for detecting the rotational position and speed of servo motors that are smaller, lighter, and have higher performance and resolution. In the case of a magnetic rotary encoder, in order to obtain high precision and high resolution, it is necessary to minimize the gap between the fixed part and the rotating part and to increase the concentricity of the fixed part and the rotating part as much as possible. Generally, the rotation center of the stator housing and rotor shaft of a motor is determined by a bearing provided between the stator housing and the rotor shaft. Bearings generally have high concentricity, but the fixed part and rotating part of conventional magnetic rotary encoders are attached to the stator housing and rotor shirt I- through couplings, respectively, at positions remote from the bearing. This causes eccentricity of the rotating part with respect to the fixed part of the rotary encoder.

[Means for solving problems]

In view of the above problems, the present invention includes a fixed part provided with a magnetic sensor on the inner circumferential surface and a rotating part provided with a magnetized pattern on the outer circumferential surface, and the fixed part is connected to the stator housing and rotor shaft of the servo motor. Provided is a magnetic rotary encoder, characterized in that the rotating section is coaxially fixed to an outer ring of a bearing provided between the two, and the rotating part is coaxially fixed to an inner ring of the bearing.

[Effect]

According to the above means according to the present invention, since the fixed part and the rotating part of the rotary encoder are provided on the bearing itself that determines the rotation center of the motor, the degree of concentricity between the rotating part and the fixed part is increased. Therefore, high precision and high resolution can be obtained. In addition, the fixed part and rotating part of the rotary encoder are directly mounted on the bearing, which reduces the number of parts and makes it smaller and lighter.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example in which a magnetic rotary encoder according to the present invention is applied to a servo motor equipped with a disk-shaped stator and rotor. Referring to the figure, a stator housing 11 of a servo motor holds a plurality of disc-shaped stator cores 12, and each disc-shaped stator core 12 has a stacked structure of stator elements including spiral winding elements. . The rotor shaft 13 is connected to the stator housing 11 through a pair of bearings 14.15.
is rotatably supported. A plurality of disc-shaped rotors 16 are fixed to the rotor shaft 13 and are arranged between the disc-shaped stator cores 12 . Each disc-shaped rotor 16 includes a plurality of permanent magnets 16b circumferentially spaced within a non-magnetic head 16a.

In the illustrated embodiment, one bearing 14 is a roller bearing and the other bearing 15 is a cross roller bearing. An outer ring 17 of the cross roller bearing 15 is fixed to the stator housing 11, and an inner ring 18 of the cross roller bearing 15 is fixed to the rotor shaft 13. The concentricity of the stator housing 11 and the rotor shaft 13 is determined by the bearing 1
It is determined based on 4°15. A ring-shaped fixed portion 20 of a magnetic rotary encoder 19 is coaxially fixed to the outer ring 17, and a ring-shaped rotating portion 21 of a rotary encoder 19 is coaxially fixed to the inner ring 18. The fixed part 20 and the rotating part 21 are made of non-magnetic material.

Referring to FIG. 2, magnetic powder 2 is provided on the outer peripheral surface of the rotating part 21.
2 is applied, and its surface is magnetized in a predetermined pattern (eg, N poles and S poles are arranged alternately in the circumferential direction). A magnetic sensor, for example, a magnetoresistive element 2 made of a permalloy thin film pattern is mounted on the inner peripheral surface of the fixed part 20.
3 is set up.

Here, the annular spigot parts 20a, 21a provided on the sides of the fixed part 20 and the rotating part 21 and the outer ring 17
A high level of concentricity is ensured by fitting into parts of the spigots provided on the sides of the inner ring 18, respectively. The fixed part 20 and the rotating part 21 can be fixed to the outer ring 17 and the inner ring 18, respectively, by screwing, gluing, welding, brazing, or the like. Since the fixed part 20 and the rotating part 21 can be integrally machined after being fixed to the outer ring 17 and the inner ring 18, the concentricity of the fixed part 20 and the rotating part 21 can be increased.

The bearing 15 integrated with the rotary encoder 19 is attached to the rotor shaft 13 by means such as press fitting, and then the outer ring 17 of the bearing 15 is fitted into the boss portion of the stator housing 11. The outer ring 17 may be fixed to the stator housing 11 by press fitting;
The outer ring 17 may be fixed to the stator housing 11 by engaging the tips of screws, pins, etc. provided in the outer ring 7 with recesses provided on the outer periphery of the outer ring 7. A presser foot holder 24 screwed onto the stator housing 11 comes into contact with the outer end of the fixed portion 20 of the rotary encoder 19 to prevent the rotary encoder 19 bearing 15 from moving in the axial direction. Here, since the bearing 15 integrated with the row encoder 19 is a cross roller bearing with no play in the axial direction, sufficient rigidity can be ensured with one bearing 15, and the simplest structure can be achieved. be able to.

In order to improve the accuracy and resolution of the low-resolution encoder 19, it is necessary to make the gap between the fixed part 20 and the rotating part 21 as small as possible. - According to the above configuration, the fixing part 2
Since the concentricity between 0 and the rotating part 21 can be increased,
A high-resolution rotary encoder can be obtained. Further, since the rotary encoder 19 can be assembled to the motor while being fixed to the bearing 15, damage to the fixed part 20 and the rotating part 21 can be prevented.

Although the illustrated embodiments have been described above, the present invention is not limited to only the embodiments of the above embodiments, and various changes can be made to the constituent elements within the scope of the invention described in the claims. .

For example, the fixing part 20 is not limited to a ring-shaped member, but may be an arc-shaped member obtained by cutting out a part of a ring.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, since the fixed portion and the rotating portion are provided in the bearing itself that determines the rotation center of the servo motor, the concentricity between the rotating portion and the fixed portion can be increased. Therefore, a high-precision and high-resolution low-resolution encoder can be provided. Moreover, since the fixed part and the rotating part are directly mounted on the bearing, it is possible to provide a small and lightweight magnetic rotary encoder with a small number of parts.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a servo motor in which a magnetic rotary encoder according to the present invention is incorporated into a servo motor, and FIG. 2 is an exploded perspective view of the rotary encoder shown in FIG. 1. DESCRIPTION OF SYMBOLS 11... Stator housing, 13... Rotor shaft, 15... Cross hair ring bearing, 17... Outer ring of bearing, 18... Inner ring of bearing, 19... Magnetic rotary encoder, 20... - Fixed part, 21... Rotating part, 20a, 21a... Inro part 22... Magnetic powder, 23... Magnetic resistance element (magnetic sensor). Figure 1

Claims (1)

[Claims] 1. A fixed part provided with a magnetic sensor on the inner circumferential surface and a rotating part provided with a magnetized pattern on the outer circumferential surface, and the fixed part is provided between the stator housing and the rotor shaft of the servo motor. A magnetic rotary encoder, wherein the rotary encoder is coaxially fixed to an outer ring of a bearing provided in the rotary encoder, and the rotating part is coaxially fixed to an inner ring of the bearing. 2. The magnetic rotary encoder according to claim 1, wherein the bearing is a cross roller bearing. 3. The fixed part and the rotating part are ring-shaped, and each of the fixed part and the rotating part has a spigot part that fits into a side part of the outer ring and the inner ring, respectively. A magnetic rotary encoder according to claim 1.