Coreless linear motor

Abstract

A coreless linear motor includes a fixed member and a movable member. The fixed member has groups of permanent magnets arranged in a yoke. The movable member has a coil assembly. The groups of permanent magnets include first and second groups of permanent magnets arranged so as to face each other. Each of the first and second groups of permanent magnets has a plurality of magnets along a longitudinal direction of the yoke. In the plurality of magnets, magnetic poles of magnets facing along the longitudinal direction of the yoke alternate. Magnetic poles of the permanent magnets along the longitudinal direction of the yoke are the same. The coil assembly has at least three coils arranged movably relative to the first and second groups of permanent magnets along the longitudinal directions of the yoke between the first and second groups of permanent magnets.

1 . A coreless linear motor comprising:
 a fixed member; and   a movable member moving relatively with respect to the fixed member;   the movable member having groups of permanent magnets arranged at the yoke;   the fixed member having a coil assembly;   the yoke having first and second facing yoke parts facing each other across a first distance and formed by magnetic materials and a connection yoke part connecting first ends of the first and second facing yoke parts;   the groups of permanent magnets including first and second groups of permanent magnets arranged so as to face the facing surfaces of the first and second facing yoke parts, each of the first and second groups of permanent magnets having a plurality of magnets along the longitudinal direction of the yoke, in the plurality of magnets of each of the first and second groups of permanent magnets, the magnetic poles of magnets facing each other along the longitudinal direction of the yoke differing from each other, and the magnetic poles of the permanent magnets along the longitudinal direction of the yoke being the same;   the coil assembly having at least three coils positioned between the facing first and second groups of permanent magnets, the at least three coils being arranged and wound solidly in multiple layers, then fastened by a binder, the end surfaces of adjacent coils connected with each other via an electrical insulation member;   the fixed member further having a nonmagnetic and electrically conductive reinforcing member fit in solid parts of said coils,   the movable member having first and second groups of permanent magnets facing the coil assembly and the yoke moving along the longitudinal direction of the coil assembly.   
     
     
         2 . A coreless linear motor as set forth in  claim 1 , wherein in the cross-sectional shape of each coil, a length facing the first and second groups of permanent magnets is longer than a length perpendicular to the first and second groups of permanent magnets. 
     
     
         3 . A coreless linear motor as set forth in  claim 1 , wherein
 in the cross-sectional shape of the reinforcing member, a length of a side facing the first and second groups of permanent magnets is longer than a length of a side perpendicular to the first and second groups of permanent magnets.   
     
     
         4 . A coreless linear motor as set forth in  claim 3 , wherein a hole through which a cooling agent passes is formed inside the reinforcing member. 
     
     
         5 . A coreless linear motor as set forth in  claim 4 , wherein heat radiating fins are formed in a hole inside the reinforcing member. 
     
     
         6 . A coreless linear motor as set forth in  claim 3 , wherein the reinforcing member is produced by aluminum or an aluminum alloy. 
     
     
         7 . A coreless linear motor as set forth in  claim 3 , wherein
 the fixed member further comprises a holding member and spacers, and   the two ends of the reinforcing member inserted into the coil assembly are held by the holding member via the spacers.   
     
     
         8 . A coreless linear motor as set forth in  claim 7 , wherein the reinforcing member and the spacers are formed by materials having a high heat conductivity and light weight. 
     
     
         9 . A coreless linear motor as set forth in  claim 8 , wherein the reinforcing member and the spacers are formed by aluminum or an aluminum alloy. 
     
     
         10 . A coreless linear motor as set forth in  claim 3 , wherein the reinforcing member is arranged spaced from the surfaces of the first and second groups of permanent magnets by exactly the distance whereby the density of the magnetic flux incident upon the surface of the reinforcing member becomes 1/2 or less of the magnetic flux density of the magnets at the center of the surfaces of the facing first and second groups of permanent magnets. 
     
     
         11 . A coreless linear motor as set forth in  claim 1 , wherein the length of the three coils in the longitudinal direction of the yoke and the length of two adjoining magnets of the first group of permanent magnets are equal. 
     
     
         12 . A coreless linear motor as set forth in  claim 1 , wherein
 the coil assembly forming an armature has a first set of 3-phase coils and a second set of 3-phase coils generating magnetic fields of opposite phases, and   the different phase coils corresponding to the first and second sets of 3-phase coils are arranged adjoining each other.   
     
     
         13 . A coreless linear motor as set forth in  claim 1 , wherein
 the yoke has a square or rectangular cross-section and has first and second facing yoke parts formed by magnetic materials and third and third facing yoke parts perpendicularly intersecting the first and second facing yoke parts and formed by magnetic materials;   the groups of permanent magnets have   first and second groups of permanent magnets arranged facing surfaces of the first and second facing yoke parts, and   third and fourth groups of permanent magnets arranged facing surfaces of the third and fourth facing yoke parts;   each of the first and second groups of permanent magnets has a plurality of magnets along a longitudinal direction of the yoke, in the plurality of magnets of the first and second groups of permanent magnets, the poles of the magnets facing each other along the longitudinal direction of the yoke being alternately different, and the poles of the permanent magnets along the longitudinal direction of the yoke being the same; and   each of the third and fourth groups of permanent magnets has a plurality of magnets along a longitudinal direction of the yoke, in the plurality of magnets of the third and fourth groups of permanent magnets, the poles of the magnets facing each other along the longitudinal direction of the yoke being alternately different, and the poles of the permanent magnets along the longitudinal direction of the yoke being the same.