Linear motor

Abstract

A linear motor having a more preferable braking function is realized with a low cost. A linear motor has a slider and a stator. A driving winding is wound around the slider. A plurality of permanent magnets forming magnetic poles which invert at a predetermined period are provided on a surface of the slider opposing the stator. Teeth are formed on the stator with a predetermined spacing therebetween. The stator extends to a region outside of an effective movable range, and a braking winding is wound around the teeth in the extended portion. When the slider moves into a region outside of the effective movable range, an induced voltage is generated in the braking winding and a current flows. A thrust in a direction opposite to the movement direction of the slider is generated by the current.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will be described in detail by reference to the drawings, wherein:

FIG. 1 is an outer view of a linear motor according to a first preferred embodiment of the present invention;

FIG. 2 is a cross sectional view of a linear motor according to a second preferred embodiment of the present invention;

FIG. 3 is a structural diagram of a table portion of a machine tool which uses a linear motor according to related art; and

FIG. 4 is a diagram showing an example circuit when a dynamic brake is constructed using a relay in a linear motor according to related art.

Claims

1. A linear motor comprising: a stator having a plurality of fixed-side teeth placed with a predetermined spacing therebetween;a slider having moving-side teeth around which a driving winding to which a drive current is supplied is wound, and a plurality of permanent magnets forming magnetic poles which invert at a period corresponding to the fixed-side teeth; anda braking mechanism which blocks driving of the slider entering a region outside of an effective movable range, whereinthe braking mechanism is provided outside of the effective movable range and comprises one or more braking teeth around which a braking winding is wound.

2. A linear motor according to claim 1, wherein the braking teeth are fixed-side teeth provided on an extension portion of the stator extending outside of the effective movable range.

3. A linear motor according to claim 1, wherein the braking teeth are teeth dedicated to braking and provided separately from the fixed-side stator.

4. A linear motor according to claim 1, wherein a resistor is connected to at least one of the braking windings.

5. A linear motor according to claim 1, wherein circuit resistances of closed circuits formed by the braking windings differ from each other according to positions of the braking teeth around which the braking windings are wound.

6. A linear motor according to claim 1, wherein a switch which opens a closed circuit formed by the braking winding is provided in the braking winding, for releasing a braking force.