Patent ID: 7404675

Claim:
A retainer for a ball bearing formed in a generally annular shape and having a plurality of pockets arranged in a circumferential direction to rollably hold a plurality of balls along a pitch circle, respectively; the pockets each having an opening on outer and inner sides in the radial direction of the retainer; the balls having a diameter and a rolling surface; the pockets each having an inner peripheral surface comprising a radially inner section which is located inward of the pitch circle of the balls in the radial direction of the retainer and a radially outer section which is located outward of the pitch circle of the balls in the radial direction of the retainer, the inner surface having a cylindrical surface which has an inner diameter being larger than the diameter of the balls at least on the radially inner section, and the radially outer section has a spherical concave surface or a pair of protruding pieces on an end section thereof, such that the gap between the radially inner section of the inner peripheral surface of the pockets and the rolling surface of the balls gradually increases toward the opening of the pockets on the inner side in the radial direction of the retainer, and that the maximum inscribing circle with respect to the opening of the pockets on the outer side in the radial direction of the retainer has a diameter smaller than the diameter of the balls; wherein the retainer is of the crown-shape, and comprises an annular main portion and a plurality of elastic pieces provided on one side in the axial direction of the annular main portion to define a pocket between a pair of the circumferentially adjacent ones of the resilient pieces, such that the main portion and elastic pieces define an inner peripheral surface which is formed in a partial conical concave shape that is inclined such that the diameter of the inner peripheral surface closer to the tip ends of the resilient pieces is larger than the diameter of the inner peripheral surface closer to the other side in the axial direction of the annular main portion.