Sealed ball bearing and bearing device

A sealed ball bearing comprising:

• an inner ring and an outer ring between which a bearing inner space is defined;
• balls disposed between the inner ring and the outer ring;
• a cage having pockets circumferentially retaining the respective balls;
• and
• a seal member closing an axial end opening of the bearing inner space,
• wherein the sealed ball bearing is used in an environment of a dmn value of 700,000 or more, the dmn value being defined by:
• dms
• =
• {
• (
• D
• +
• d
• )
• /
• 2
• }
• ×
• n
• ,
• D:
• Bearing outer diameter,
• d:
• Bearing inner diameter, and
• n:
• Rotational speed,
• wherein the seal member comprises a seal lip that is fixed to one of the inner ring and the outer ring, and that is in sliding contact with a seal sliding surface of the other of the inner ring and the outer ring,
• wherein the seal lip includes a plurality of protrusions circumferentially spaced apart from each other such that gaps are defined between respective circumferentially adjacent pairs of the protrusions, and such that, during rotation of the bearing, a lubricating oil is dragged from the gaps to between the protrusions and the seal sliding surface so as to form an oil film therebetween, thereby achieving a fluid lubrication regime between the seal lip and the seal sliding surface,
• wherein the cage is a crown-shaped cage containing an engineering plastic, and comprising an annular base;
• and a plurality of pillars protruding unidirectionally from the base,
• wherein a dimensional relationship among φx, Ry, and Rz satisfies φx<2Ry<2Rz, wherein φx is a diameter of each of the balls, Ry is a radius of a radially inner peripheral surface of each of the pockets on a cross section passing through a pocket center of the pocket and including a center axis of the bearing, and Rz is a radius of a circumferentially inner peripheral surface of each of the pockets on a cross section taken through the pocket center in a direction orthogonal to a bearing radial straight line passing through the pocket center, and
• wherein the circumferential inner peripheral surface of each of the pockets has a first inner peripheral surface portion on a side of the base;
• and a second inner peripheral surface portion extending toward distal ends of corresponding ones of the pillars beyond the first inner peripheral surface portion, and a center of the second inner peripheral surface portion is offset toward the base relative to a center of the first inner peripheral surface portion.