Patent ID: 7501724
Filing Date: 2009-03-10
Classification: H02K

Abstract:
1. A movable assembly for a cylinder type linear motor, the cylinder type linear motor having a movable core fixed to one or more direct drive shafts and capable of performing a reciprocal, linear motion; wherein the movable core is constructed of a laminated yoke which is formed of a plurality of electromagnetic steel plates laminated in an axial direction of the direct drive shafts; wherein the laminated yoke has paired side surfaces which extend along the direct drive shafts, and are so disposed as to face each other with the direct drive shafts being therebetween; wherein a plurality of permanent magnets are so fixed to each of the paired side surfaces as to be juxtaposed in the axial direction of the direct drive shafts; wherein the plurality of permanent magnets on one of the paired side surfaces are arranged in such a manner that polarity appearing on an outer surface of one of the permanent magnets is different from that of the other permanent magnets adjacent to the one of the permanent magnets, and is also different from that of the opposing permanent magnets on the other of the paired side surfaces; wherein the one or more direct drive shafts each have a yoke mounting portion to which the movable core is fixed and paired supported portions provided at both axial ends of the yoke mounting portion and supported by bearings; wherein the one or more direct drive shafts are so shaped that the yoke mounting portion has a smaller cross section in a direction orthogonal to the axial direction than that of the supported portions; wherein the electromagnetic steel plates are each constructed of two divided electromagnetic steel plate pieces; and wherein the two divided electromagnetic steel plate pieces are so shaped, when combined to enclose the one or more direct drive shafts, as to be able to contact each other and to form one of the electromagnetic steel plates that constitutes one layer of the laminated yoke.