Patent ID: 7837391
Filing Date: 2010-11-23
Classification: F16C,H02K

Abstract:
1. A bearing retainer unit, for application in an electric motor furnished with a rotor that rotates centered on a rotational axis, the bearing retainer unit comprising: a metal bearing bushing of cylindrical form including a bushing inner surface and a bushing outer surface, and defining a communicating hole extending laterally therethrough and by which the inside and outside of the bushing communicate; and a molded part having a molded cylinder portion covering the bushing outer surface, a cylindrical bearing-positioning portion disposed inside of the bushing and covering the bushing inner surface, and a linking portion that closes off the communicating hole and links the molded cylinder portion and the bearing positioning portion, the cylindrical bearing-positioning portion having upper and lower end surfaces facing in opposite directions axially with respect to the cylindrical bearing-positioning portion, and frustum-shaped inner circumferential surfaces extending into the cylindrical bearing-positioning portion from the upper and lower end surfaces, respectively, the frustum-shaped inner circumferential surfaces meeting along a die-parting line which extends circumferentially along an axially inner part of the cylindrical bearing-positioning portion, and wherein the inner diameter of the cylindrical bearing-positioning portion is smallest at the die-parting line; whereby said molded part can be formed and integrated with said bearing bushing by an insert molding technique employing at least a pair of mold dies made up of a first die having a frustum-shaped outer circumferential surface corresponding to one of the inner frustum-shaped inner circumferential surfaces of said bearing positioning portion, and a second die having a frustum-shaped outer circumferential surface corresponding to the other of the inner frustum-shaped inner circumferential surfaces of said bearing positioning portion, such that