1. Technical Field
This disclosure relates to a linear motor.
2. Description of the Related Art
A linear motor includes, for example, a stator and an armature core. The stator includes a field core and a plurality of permanent magnets disposed at the field core. The armature core has an armature winding wire. The armature core is disposed so as to dispose a magnetic void with the permanent magnets. The linear motor generates a cogging thrust. This cogging thrust causes vibrations and a noise during driving the linear motor. Furthermore, this cogging thrust causes deteriorations in positioning performance and speed stability. Therefore, the cogging thrust in the linear motor is preferably small as much as possible. For example, JP-A-2003-299342 and JP-A-2004-364374 disclose techniques to reduce such cogging thrust in the linear motor.
With the technique disclosed in JP-A-2003-299342, a shape of auxiliary teeth (end teeth) of an armature core is shaped by cutting off an outer distal end of main teeth. This reduces a cogging thrust. With the technique disclosed in JP-A-2004-364374, a shape of main teeth to which winding wires are installed in an armature core and a shape of auxiliary teeth at both ends of the armature core differ from one another. This reduces a cogging thrust.
USPTO Backgrounds
USPTO Backgrounds