JPS63302755A - Linear motor - Google Patents

Abstract

PURPOSE:To cool coils simply and effectively by cooling said coils through air suction means generating air flow in the vicinity of said coil. CONSTITUTION:Permanent magnet 1B, 1C and yokes 2B, 2C are arranged in opposition to each other via non-magnetic material spacers 3, and coils 5 wound on a bobbin 4 move in a levitated state through a space between them. Air flow is generated in the vicinity of said coils 5 by a negative pressure generated through a vacuum source 8, the coils 5 are cooled by said air flow, and the air flow changed into warm air by warming is drawn outward of a linear motor via a through hole 6 and piping 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multipolar linear motor in which a coil moves in a magnetic field formed by a magnet, and particularly to a cooling device for the motor.

[Prior art]

A linear motor generally has a primary side (fixed side) consisting of a field magnet (permanent magnet) and a yoke forming a magnetic circuit, and a secondary side having a moving coil wound around a bobbin, and a position detector. and said 2 in a closed loop control circuit.
Configured to control the position and speed of the next side.

FIG. 2 is a partial perspective view of a conventional multipolar linear motor.

In Figure 2, the negative permanent magnet (field magnet) I
A and the yoke 2A and the permanent magnet 1B%IC and the corks 2B and 2C on the other side face each other with a non-magnetic spacer 3.3 interposed therebetween, and the coil 5 wound on the bobbin 4 is passed through the space between them. Configured to move.

The position and speed of the coil 5 is controlled by the current and frequency supplied to the coil.

[Problem that the invention seeks to solve]

In the linear motor described above, when a current is passed through the coil 5, Joule heat is generated and the coil temperature increases, so that the following problem may occur.

(i) When a linear motor is used in a precision device such as a head drive motor for an optical disk, the accuracy of the precision device may be disrupted due to temperature changes.

(ii) The electrical characteristics of the linear motor change due to the rise in temperature of the coil 5.

(1i) Magnet lA11B placed near the coil 5,
As the temperature of the IC increases, the life of the magnet is shortened.

[Means for solving problems]

The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to provide a linear motor that can simply and effectively cool a coil and solve the problems of the prior art described above.

The present invention achieves the above object by transporting the heat of the coil to the outside by means of an air suction means that generates an air flow in the vicinity of the coil, and suppressing the rise in temperature of the coil.

〔Example〕

FIG. 1 is a cross-sectional view of one embodiment of a linear motor according to the present invention, and the present invention will be specifically described below with reference to FIG.

In FIG. 1, the overall structure of the motor is the same as in FIG.
C are arranged to face each other with a non-magnetic spacer 3.3 in between, and the coil 5 wound around the bobbin 4 is moved in a floating state through the space therebetween.

The gap (air gap) between the magnet IAS IB, IC and the coil 5 is set to a relatively small value (for example, about 0.5 mm).

As shown in the figure, the bobbin 4 is formed with a hole 6 that passes through it vertically and communicates the air gap with the upper surface of the bobbin, and the outer opening of the through hole 6 is connected to a suction pump, etc. is connected to a vacuum source 8.

In this way, by activating the vacuum source 8, air is sucked from the air gap around the coil 5, and an air flow is generated near the coil 5 as shown by the arrow in FIG. It is configured to transport heat to the outside to cool the coil 5 and prevent its temperature from rising.

That is, an air flow is generated in the vicinity of the coil 5 by the negative pressure generated by the vacuum source 8, and the coil 5 is cooled by this air flow, and the air flow is warmed and turned into warm air, and the through hole 6 and the piping 7 are heated. It is configured so that it is sucked out of the linear motor through the linear motor.

According to the embodiment structure of the linear motor described above, the following effects can be achieved.

(i) Since the air gap between the coil 5 and the magnets IA, IB, and IC is generally set to be narrow (for example, 0.5 sn), an air flow with a relatively high velocity will occur near the coil 5.

Therefore, a high heat transfer coefficient was obtained between the coil 5 and the air flow, and the coil 5 could be efficiently cooled.

(11) Since the coil 5 is cooled by suction rather than blowing air, it does not scatter dirt or dust, and it was possible to obtain a linear motor that would not cause any problems even when installed in precision equipment in a clean room. .

(■1) A normal cooling circuit requires at least two pipes, one on the low temperature side and one on the high temperature side, but in the example structure, only one pipe 7 is required, resulting in an extremely simple structure. The coil 5 could be effectively cooled.

(Effects of the Invention) As is clear from the above description, according to the present invention, the coil is cooled by an air suction means that generates an air flow near the coil. A linear motor can be obtained that can effectively prevent temperature rise.

In addition, since the rise in temperature of the coil is suppressed, thermal deformation of the equipment to which the linear motor is installed is prevented, the electrical characteristics of the linear motor are maintained stably and well, and the life of the linear motor's magnets is extended. It becomes possible to achieve effects such as:

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment of a linear motor according to the present invention, and FIG. 2 is a partial perspective view of a conventional linear motor. IA% IB, IC・・・−１−−・・Magnet, '4・
−−1−−−・−・Bobbin, 5−・・−・−1−−− Coil, 6・−・−・・−Through hole, 7・−−−−−
・・・−・Piping, 8−・−・−Vacuum source. Agent Patent Attorney Yasushi Ooto Figure 1

Claims (2)

[Claims] (1) A linear motor characterized in that the coil is cooled by air suction means that generates an air flow near the coil. (2) A through hole is provided in the bobbin of the coil, and air is sucked through the through hole.
Linear motor as described in section.