JP2003169436A - Motor fitted with optical encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor fitted with an optical encoder which is highly reliable against oil mist. <P>SOLUTION: The vicinity of the external periphery of a disc 28 has a small space from a ball bearing 25 and a bracket 24 on an anti-load side. When a motor 21 rotates, an air current arises on the side of the disc 28 by the existence of the disc 28, and air flows in from an outer communication hole 24b to the disc 28, so that the disc 28 is provided on an anti-encoder side and the air current is circulated positively in the vicinity of the ball bearing 25 where oil mist generates, so as to prevent the oil mist from adhering to the optical parts of the encoder. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor with an optical encoder used for high speed rotation.

[0002]

2. Description of the Related Art Conventionally, servo motors have been the mainstream of motors used in industrial equipment because high positioning accuracy is required.

This servo motor is equipped with a high-resolution detector for detecting the rotational speed and rotational position, and an inner rotor type motor with a small rotational inertia is used for highly accurate positioning.

A servo motor is generally provided with a high-resolution optical encoder on the side opposite to the load side, and the outside thereof is covered with a protective cover to prevent foreign matter from flying.

[0005]

However, when the motor rotates at a high temperature, the ball bearing produces oil mist in which the lubricating grease is vaporized. This oil mist scatters along with the air flow caused by the rotation of the rotor and the rotary code plate and adheres to the optical components and the high-resolution code plate,
There has been a problem that the amount of light received and emitted decreases, and detection becomes impossible in the worst case.

Therefore, a labyrinth seal is provided near the ball bearing on the encoder side or an adsorbing means is provided to prevent the oil mist from adhering.

However, due to the increase in speed of equipment such as semiconductor devices and spindle motors of machine tools, motors are used at higher speeds, the bearing temperature rises, and the amount of oil mist generated increases. Then, the flow of air around the rotating part also increases in the sealed space. The generated oil mist scatters along with this air flow and adheres to the optical components of the optical encoder. Therefore, the conventional labyrinth structure cannot protect the oil mist from the oil mist.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a motor with an optical encoder having high reliability against oil mist at a low cost.

[0009]

In order to solve the above problems, a motor with an optical encoder according to the present invention comprises a motor,
An optical encoder is provided in a space separated from the motor, and a communication hole is provided at a specific portion different in the radial direction of the partition wall between the motor and the optical encoder to circulate the air flow.

[0010]

In order to solve the above-mentioned problems, a motor with an optical encoder according to a first aspect of the present invention includes a motor and an optical encoder in a space separated from the motor. The air flow is circulated by providing communication holes at different points in the radial direction of the partition wall between the encoders.Because communication holes are provided at different points in the radial direction, the difference in air flow caused by the difference in rotation radius is used. You can control the air flow.

According to another aspect of the motor with an optical encoder of the present invention, there is provided a motor in which a ball bearing in which an inner rotor is housed in a bracket is rotatably supported, and a rotating portion provided on an anti-load side rotating shaft outside the motor. An optical encoder configured with a fixing portion provided on the anti-load side bracket, and a protective cover that covers the optical encoder and fixes the anti-load side bracket, and the anti-load side bracket includes a space for the motor and the encoder. A connection hole is provided to circulate the air flow in the space between the motor and encoder.The air flow can be forcibly circulated through the connection hole at a specific location.If the connection hole is moved away from the ball bearing, the oil mist It is less likely to be affected by this air flow, and it is possible to prevent it from adhering to the optical section.

The motor with an optical encoder according to a third aspect of the invention is provided with a disc having a larger outer diameter than the outer ring of the ball bearing, the disc being in contact with the inner ring of the ball bearing of the anti-load side bracket and fixed to the rotating shaft. Since the communication hole is provided near the outer circumference of the ball bearing and the airflow is actively circulated near the ball bearing on the non-load side, it is possible to prevent oil mist from adhering to the optical component.

Further, in the motor with an optical encoder according to a fourth aspect, the communication hole is provided in the vicinity of the outer circumference of the rotor. By positively separating the position of the communication hole from the rotating portion of the encoder, the circulating air flow Can be less affected.

Furthermore, the motor with an optical encoder according to a fifth aspect is mounted on a spindle drive, and is most suitable for high speed rotation drive of a spindle of a machine tool or the like.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) In FIG. 1, 11 is a motor, 12 is an inner rotor, 13 is a rotating shaft, 14 is an anti-load side bracket, 15 is a ball bearing, 16 is an optical encoder, and 17 is a protective cover. Is.

In the optical encoder 16, a fixed portion 16a including a light emitting / receiving portion is attached to the anti-load side bracket 14, and a rotary portion 16b having a code plate is fixed to the rotary shaft 13.
It is obtained by fixing with a gap. Further, the protective cover 17 covers the entire optical encoder 16 to protect foreign matter from entering from the outside.

The motor space 11a and the encoder space 16c are separated from each other by the partition wall 14a of the anti-load side bracket 14.
It is divided by. By providing the partition walls 14a with the communication holes 14b and 14c that connect the two spaces at different positions in the radial direction, an air flow difference occurs between the inside and the outside, and the air in the two spaces circulates through the communication holes 14b and 14c. To do.

The positions of the communication holes 14b and 14c are set at specific positions depending on the outer diameter of the ball bearing, the outer diameter of the rotor and the positions of the optical parts of the encoder.

For example, when the optical component is located outside the outer diameter of the rotor, the communication holes 14b and 14c are provided near the outer circumference of the rotor away from the ball bearing 15, and the airflow is forcibly circulated near the outer circumference of the rotor. . In other words, the oil mist is less likely to be affected by this air flow and stays in the vicinity of the ball bearing 15. Even if the oil mist is affected by the air flow, the air flow circulates inside the optical component, so that the optical components such as the light emitting / receiving element and the code plate. It is possible to prevent the oil mist from adhering to the.

(Embodiment 2) In Embodiment 2, a disk and a communication hole are provided in the vicinity of a ball bearing, and an air flow is forcibly circulated in the vicinity of the ball bearing which is a source of oil mist.

In FIG. 2, reference numeral 21 is a motor, 22 is an inner rotor, 23 is a rotating shaft, 24 is an anti-load side bracket, 25 is a ball bearing, 26 is an optical encoder, 27 is a protective cover, and 28 is a disk. Is.

The differences from the first embodiment will be mainly described below.

The outer diameter of the disc 28 is larger than the outer diameter of the ball bearing 25, and the inner diameter is fixed to the rotating shaft 23 and abuts on the inner ring of the ball bearing 25. Then, communication holes 24a and 24b are provided in the outer periphery of the disk 28, that is, in the vicinity of the outer periphery of the ball bearing 25.

Around the outer periphery of the disc 28, there is a small gap between the ball bearing 25 and the anti-load side bracket 24, and when the motor 21 rotates, the disc 28 will be present depending on the presence or absence of the disc 28.
An airflow is generated on the side, and the air flows into the disk 28 side from the outer communication hole 24b.

This structure is effective when the position of the optical component and the outer diameter of the rotor are close to the ball bearing, and the disc 28 is provided on the side opposite to the encoder so that the disc 28 is positively positioned near the ball bearing where oil mist is generated. It is better to circulate the airflow.

This makes it possible to prevent the oil mist from adhering regardless of the outer diameter of the rotor and the position of the optical parts of the encoder.

Generally, ball bearings are provided with shield plates fixed to the outer ring at both ends, but there is a gap on the inner ring side, and when seen microscopically, there is a gap in the axial direction. Since this gap can be regarded as a communication hole, a plurality of communication holes provided in the vicinity of the outer circumference of the ball bearing may be provided at the same radial position in the circumferential direction.

If the second embodiment and the first embodiment are used together,
The optical components can be more reliably protected from oil mist.

As described above, by connecting the two partitioned spaces with the communication hole and controlling the air flow, it is possible to prevent oil mist from adhering to the optical parts of the encoder.

[0031]

As is apparent from the above-described embodiments, according to the inventions of claims 1 and 2, a communication hole is provided at a specific location different in the radial direction of the partition wall to circulate the air flow. It is possible to control the air flow by utilizing the difference in air flow caused by the difference in the above, and it is possible to suppress the oil mist from adhering to the optical component by moving the communication hole away from the ball bearing.

According to the third aspect of the present invention, the airflow is positively circulated in the vicinity of the anti-load side ball bearing, so that it is possible to prevent oil mist from adhering to the optical parts of the encoder.

According to the fourth aspect of the present invention, by positively separating the position of the communication hole from the rotary portion of the encoder, it is possible to prevent oil mist from adhering to the rotary portion of the encoder.

Further, according to the invention of claim 5, it is possible to prevent the oil mist from adhering to the optical parts of the encoder as in the above effect, so that it is particularly reliable for high-speed rotation applications such as spindle drive of machine tools. A highly efficient motor with an optical encoder can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a motor with an optical encoder according to a first embodiment of the present invention.

FIG. 2 is a sectional view of an essential part of a motor with an optical encoder according to a second embodiment of the present invention.

[Explanation of symbols]

11,21 motor 11a motor space 12,22 rotor 13,23 rotating shaft 14,24 Anti-load side bracket 14a partition wall 14b, 14c, 24a, 24b Communication hole 15,25 ball bearings 16,26 Optical encoder 16a Fixed part 16b rotating part 16c Encoder space part 17,27 Protective cover 28 discs

Claims (5)

[Claims] 1. A motor, and an optical encoder provided in a space separated from the motor, wherein communication holes are provided at specific portions different in a radial direction of a partition wall between the motor and the optical encoder to circulate an air flow. A motor with an optical encoder characterized by. 2. A motor, which rotatably supports an inner rotor with a ball bearing housed in a bracket, a rotating portion provided on the anti-load side rotating shaft outside the motor, and a fixed portion provided on the anti-load side bracket. Optical encoder, and a protective cover that covers the optical encoder and is fixed to the anti-load side bracket, and a communication hole that connects the motor and the space portion of the encoder is provided in the anti-load side bracket. The motor with an optical encoder according to claim 1, wherein the air flow is circulated. 3. A disc having a larger outer diameter than an outer ring of the ball bearing, which is in contact with the inner ring of the ball bearing of the anti-load side bracket and is fixed to the rotating shaft, and a communication hole is provided near the outer periphery of the ball bearing. The motor with an optical encoder according to claim 2. 4. The motor with an optical encoder according to claim 2, wherein a communication hole is provided near the outer circumference of the rotor. 5. A machine tool equipped with the motor with an optical encoder according to claim 1 for driving a spindle.