Linear motor

• US 5,602,431 A
• Filed: 09/29/1994
• Issued: 02/11/1997
• Est. Priority Date: 09/29/1993
• Status: Expired due to Fees

• Current Assignee: Oriental Motor Company Limited
• Original Assignee: Oriental Motor Company Limited
• Inventors: Iwasa, Takao, Satomi, Hirobumi
• Primary Examiner(s): Dougherty, Thomas M.
• Assistant Examiner(s): JONES, JUDSON
• Application Number:
  US08/315,063
• Time in Patent Office: 866 Days
• Field of Search: 310/12, 310/13, 310/14, 310/68 B, 310/49 R, 318/135
• US Class Current: 310/14
• CPC Class Codes: H02K 41/02 Linear motors; Sectional motors
• CPC Class Codes: H02K 41/031 of the permanent magnet type

Abstract

A linear motor is operated as an m-phase linear pulse motor or a brushless DC linear motor capable of producing large driving force. The linear motor includes an even number N of salient poles 11, 12, . . . disposed at an equal pitch angle and includes a stator 1 having a plurality of permanent magnet poles disposed on inner peripheral surfaces of the salient poles to have polarities different from each other in the shaft direction and a mover 3 disposed movably in the shaft direction. The salient poles are constituted by pairs of the salient poles adjacent to each other and include m sets of salient pole groups each composed of (N/m) salient poles disposed at an angle of (720 m/N) degrees and windings W1, W2, . . . wound on (N/m)-1 or (N/m)-2 salient poles belonging to the salient pole groups are connected to have opposite polarities between the pair of salient poles and are connected to have the same polarity between the salient poles which do not constitute the pair of salient poles and are disposed to interpose the salient poles for the other phase to constitute phase windings for m phases. Remaining salient poles of the salient pole group are caused to detect a position and a movement direction of the mover 3 as sensor poles S_A and S_B.

Claims

1. A linear motor comprising a stator including a stator core having an even number of salient poles disposed at an equal pitch angle radially inward and windings wound on said salient poles individually and a mover including a mover core disposed within said stator to be supported movably in the shaft direction and having a plurality of mover teeth disposed on an outer peripheral surface thereof in the shaft direction, characterized in that

a plurality of permanent magnet poles magnetized radially to have polarities different alternately in the shaft direction are disposed at an equal pitch on inner peripheral surfaces of said salient poles of said stator core and said mover teeth are disposed at a pitch equal to twice the disposition pitch of said permanent magnet poles, said mover core being formed by laminating mover core elements each formed by laminating a predetermined number of mover iron plates of said mover core with said mover core elements being rotated sequentially by an angle determined by an arrangement of teeth disposed on outer peripheral portions of said mover iron plates, said stator salient poles being constituted by pairs of said salient poles adjacent to each other and including m sets of salient pole groups each composed of (N/m) salient poles disposed uniformly at an angle of (720 m/N) degrees where the number of salient poles is N and the phase number of said motor is m, said windings wound on (N/m)-1 or (N/m)-2 salient poles belonging to said salient pole groups being connected to have opposite polarities to each other between said pair of salient poles and being connected to have the same polarity to each other between said salient poles which do not constitute said pair of salient poles and are disposed opposite to each other to interpose said salient pole pair belonging to other salient poles therebetween to constitute phase windings for m phases, remaining salient poles which do not participate in phase configuration of said salient pole group for the phases being caused to detect a position in the shaft direction and a movement direction of said mover as sensor poles, whereby said linear motor can be operated as an m-phase linear pulse motor or a brushless DC linear motor.

2. A linear motor according to claim 1, wherein said stator core includes 8k salient poles when the phase number m is 2 and k is an integer larger than or equal to 1, and k sets of tooth groups each set having two teeth disposed with an angle of (135/k) degrees therebetween are disposed on an outer peripheral portion of said mover iron plate, said tooth groups being disposed with an angle of (360/k) degrees one another, said mover core being formed by said mover core elements laminated with sequential rotation by (135/k) degrees, a disposition pitch of said permanent magnet poles disposed on said stator core being 4t when a thickness of said stator core element in the shaft direction is t.

3. A linear motor according to claim 1, wherein said stator core includes 12k salient poles when the phase number m is 3 and k is an integer larger than or equal to 1, and k sets of tooth groups each set having two teeth disposed with an angle of (150/k) degrees therebetween are disposed on an outer peripheral portion of said mover iron plate, said tooth groups being disposed with an angle of (360/k) degrees one another, said mover core being formed by said mover core elements laminated with sequential rotation by (150/k) degrees, a disposition pitch of said permanent magnet poles disposed on said stator core being 6t when a thickness of said stator core element in the shaft direction is t.