JPH0583924A - Linear motor - Google Patents

Abstract

PURPOSE:To prevent the attraction of magnetic substance powder and magnetic metallic foreign matters by forming an air gap between a permanent magnet and a stator at both ends in the direction of movement of a needle so as to be made larger than that between the needle and the stator. CONSTITUTION:A needle 1 and a stator 2 are supported rectilinearly movably in the directions of the arrows D, E by a linear way 10, the needle 1 is composed of a sliding table 3, a yoke 4 and a permanent magnet 5, and permanent magnets are arranged at both ends in the direction of movement of the yoke 4. Structure in which the air gap I between the permanent magnet 5 and a core 6 is reduced as much as possible and motor efficiency is improved is formed, and the permanent magnet 9 attracts dust from surrounding environment. When the needle 1 is moved, magnetic metallic foreign matters in motor surrounding environment are attracted to the permanent magnet 9 having a large air gap with the core 6 of the stator 2, thus preventing the attraction of the magnetic metallic foreign matters to the permanent magnet 5. Accordingly, the damage of the permanent magnet 5 or the core 6 and a coil 7 due to magnetic metallic foreign matters in the fine air gap I section can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor which produces thrust by electromagnetic force.

[0002]

2. Description of the Related Art FIG. 5 shows a cross-sectional view of a conventional linear motor having a structure in which a mover is made of a permanent magnet and an iron core is made of a coil and an armature is made of a stator.

In FIG. 5, 2 is a stator, 1 is a mover supported by the stator 2 so as to be movable in the directions of arrows A and B, and
The mover 1 includes a slide table 3, a yoke 4, and a permanent magnet 5.
The stator 2 includes an iron core 6, a coil 7,
It is composed of a stator base 8. Reference numeral 11 is a bellows which is provided at both ends of the slide table 3 in the moving direction and covers the permanent magnet 5, the iron core 6, and the coil 7.

The operation of the linear motor configured as above will be described below. In the permanent magnet 5 that constitutes the mover 1, thrust is generated by the electromagnetic force of the iron core 6 that constitutes the stator 2 and the coil 7 wound around the iron core 6, and the mover 1
Moves on the stator 2.

In this conventional linear motor, the permanent magnet 5 of the mover 1 adsorbs magnetic powder as dust or magnetic metal as foreign matter in the motor manufacturing process or the environment in which the motor is used. Magnetic substance powder or magnetic metal is formed in the minute gap I between the mover 1 and the stator 2 in the permanent magnet 5 of the mover 1.
Alternatively, the permanent magnet 5, the iron core 6, or the coil 7 may be damaged by colliding with the iron core 6 or the coil 7 of the stator 2.

In order to prevent this damage, the conventional permanent magnet 5 has been used.
Then, the bellows 11 that covers the iron core 6 and the coil 7 is attached, the motor use environment is limited, or the air gap I is increased even if the motor efficiency is reduced.

Incidentally, FIG. 5 is an example, and the same problem occurs in a linear motor having a structure having an iron core or an iron core coil instead of the permanent magnet on the mover side.

[0008]

That is, in the above-described conventional configuration, in a linear motor that generates a thrust force by an electromagnetic force through a minute gap, magnetic flux generated in the gap causes magnetic powder or magnetic metal foreign matter to be generated. There is a problem that the linear motor is damaged by being adsorbed in the air gap. Therefore, conventionally, methods such as mounting bellows on the motor, limiting the motor usage environment, and increasing the air gap I were taken. However, there is a new problem that the efficiency of the motor is reduced.

An object of the present invention is to prevent adsorption of magnetic powder or magnetic metallic foreign matter into voids by a simple method other than the above.

[0010]

In order to solve the above problems, the present invention provides permanent magnets at both ends in the moving direction of the mover, and the gap between the permanent magnet and the stator is the gap between the mover and the stator. It was set to be larger.

[0011]

When the mover linearly reciprocates on the stator, the permanent magnets at both ends of the mover attract magnetic particles such as dust in the surrounding environment and magnetic metal foreign matters, and the gap between the mover and the stator is increased. It is possible to prevent the magnetic powder and the magnetic metal foreign matter from entering the voids, and prevent the motor from being damaged.

[0012]

1 is a sectional view of a linear motor according to an embodiment of the present invention, and FIG. 2 is a sectional view of the linear motor according to an embodiment of the present invention taken along the line C--C in FIG.
In FIG. 1 and FIG. 2, the mover 1 and the stator 2 are indicated by arrows D and E by a linear way (air bearing, magnetic bearing) 10.
It is supported so that it can move linearly in any direction.

The mover 1 is composed of a slide table 3, a yoke 4 and permanent magnets 5, and permanent magnets 9 are installed at both ends of the yoke 4 in the moving direction.

Here, the permanent magnet 5 is the iron core 6 of the stator 2.
This is a main permanent magnet for generating thrust by the electromagnetic force of the coil 7 and the coil 7 wound around it, and has a structure in which the air gap I with the iron core 6 is made as small as possible to improve the motor efficiency.

Further, the permanent magnet 9 is for adsorbing magnetic powder as dust from the surrounding environment and magnetic metal foreign matter, and the gap χ between the permanent magnet 9 and the stator 2 is the same as the permanent magnet 5. It is arranged so as to be larger than the gap I with the stator 2. The first embodiment of the arrangement shape of the permanent magnets 9 is shown in FIG.
(A), the second embodiment in FIG. 3 (b), the third embodiment in FIG. 3 (c), and the fourth embodiment in which the thickness of the permanent magnet 9 is reduced and the air gap χ is increased. Examples are shown in FIGS. 4 (a) and 4 (b).

In this embodiment, the permanent magnet 5 is used for the mover 1. However, a similar attraction permanent magnet can be used even when the mover has only the iron core or a coil wound around the iron core. It can be configured to have.

When the mover 1 is moved in the above structure, the magnetic metal foreign matter in the environment surrounding the motor is attracted to the permanent magnet 9 having a large gap with the iron core 7 of the stator 2, and the magnetism to the permanent magnet 5 is increased. Adhesion of metal foreign matter can be prevented and micro voids I
It is possible to prevent the permanent magnet 5 or the iron core 6 and the coil 7 from being damaged by the foreign matter of the magnetic metal in the portion.

[0018]

As described above, according to the present invention, permanent magnets are provided at both ends in the moving direction of the mover so that the gap between the permanent magnet and the stator is larger than the gap between the mover and the stator. Thus, when the mover linearly reciprocates on the stator, the permanent magnets at both ends of the mover attract magnetic powder or magnetic metal foreign matter as dust in the surrounding environment, and the magnetic force between the mover and the stator increases. It is possible to prevent the magnetic powder or the magnetic metal foreign matter from entering the void, and prevent the motor from being damaged.

With this method, it is possible to use the motor in a bad environment without lowering the efficiency of the linear motor, and it becomes unnecessary to install bellows, and it is provided at both ends in the moving direction of the mover. The permanent magnet can increase the amount of magnetic flux of the motor and improve the motor performance.

[Brief description of drawings]

FIG. 1 is a sectional view of a linear motor according to an embodiment of the present invention.

FIG. 2 is a diagram of a linear motor according to an embodiment of the present invention.
Sectional view of the state of cutting off the line C-C

FIG. 3 (a) is a layout view of permanent magnets of a linear motor according to a first embodiment of the present invention, and (b) is a layout view of permanent magnets of a linear motor according to a second embodiment of the present invention. FIG. 7C is a diagram showing an arrangement shape of permanent magnets of the linear motor in the third embodiment of the present invention.

FIG. 4A is a cross-sectional view of a mover of a linear motor according to a fourth embodiment of the present invention, and FIG. 4B is an arrangement shape diagram of permanent magnets of a linear motor according to the fourth embodiment of the present invention.

FIG. 5 is a cross-sectional view of a conventional linear motor

[Explanation of symbols]

 1 Mover 2 Stator 3 Slider Table 4 Yoke 5 Main Permanent Magnet 6 Iron Core 7 Coil 8 Stator Base 9 Adsorption Permanent Magnet 10 Linear Way (or Air Bearing, Magnetic Bearing) 11 Bellows

Claims (1)

[Claims] 1. A linear motor having a stator and a mover that generate a thrust force by an electromagnetic force, the gap being larger than the gap between the stator and the mover at both ends in the moving direction of the mover. A linear motor characterized in that a permanent magnet is arranged so as to have.