Crown-type retainer for ball bearings, and ball bearing

A crown type cage for a ball bearing comprising:

• an annular main portion;
• a plurality of pillar portions protruding in an axial direction from an upper surface of the main portion at predetermined intervals in a peripheral direction;
• and
• a spherical pocket formed between the adjacent pillar portions and having a spherical recessed surface capable of holding a ball, wherein:
• the pillar portion has a pair of claw portions of which tip end portions are spaced apart from each other and a connection portion that connects the pair of claw portions;
• an inlet having a width shorter than a diameter of the ball and for inserting the ball is provided between the tip end portions of the two adjacent claw portions forming the pocket,
• a radius of curvature of the spherical recessed surface of the pocket is greater than a radius of curvature of a rolling surface of the ball;
• an outer diameter of the claw portion is smaller than an outer diameter of the main portion;
• a radial width of the claw portion is ½ or less of a radial width of the main portion;
• an axial width H1 from an upper surface of the connection portion of the pillar portion to a bottom surface of the main portion is ½ or less of an axial width H2 of the crown type cage for a ball bearing;
• in the main portion, an opening portion that opens in the axial direction is provided between the adjacent pockets, the claw portion and the opening portion are provided offset in a radial direction, and the opening portion is positioned on a radially outer side of the claw portion;
• the bottom surface of the main portion has a projection portion protruding in the axial direction between the adjacent opening portions;
• and
• the axial width H1 from the upper surface of the connection portion of the pillar portion to the bottom surface of the main portion, the axial width H2 of the crown type cage for a ball bearing, an axial width H3 of the main portion at a bottom portion of the pocket, and an axial width H4 from the upper surface of the main portion to the bottom surface of the main portion, satisfy:
• H3<H4<H1≤(H2/2).