The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 27, 1990
Filed:
Aug. 12, 1988
Tetsuo Oishi, Ise, JP;
Shinko Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
Since the DC linear brushless motor is constructed based on a principle that an ordinary DC brushless motor is developed into a linear shape, it is inevitable that its stator should have a large number of permanent magnets arrayed linearly and the adjacent poles of which are separated by many gaps, in addition, that its armature core has a finite length at each end in the direction of the travel of the moving member. Both the gaps or boundaries between adjacent magnetic poles of the stator and the teeth slots as well as the both ends in the armature core result in synthesized detent thrusts, and these detent thrusts are not preferable for applying this type linear motor to OA devices or precise measuring device. Though it is possible to reduce the detent thrust due to the gaps or boundaries between poles in the stator and the parallel slots between the teeth of the armature core by arraying the permanent magnets in skewed manner with respect to the lengthwise axis of the stator, there has not been suitable and effective way to reduce or eliminate the detent thrust caused by the end effect of the armature core. In view of this, the linear DC brushless motor of this type has solved the problem by reducing the unit volume of the tooth or teeth at the axial ends of the armature core by either cutting out a part of the tooth or teeth, attaching a rightangled triangular pillar(s) or by slantly cutting the teeth at each end of an armature core in the direction of travel.