Seal assembly, and rolling bearing and hub unit assembled therewith

A rolling bearing for supporting a wheel of an automobile comprising:

• an inner race having an outer peripheral surface formed with an inner raceway;
• an outer race having an inner peripheral surface formed with an outer raceway;
• a plurality of rolling members provided between the inner raceway and outer raceway for relative rotation between the inner race and outer race;
• and
• a seal assembly having a support member and a seal member to cover a space between the outer peripheral surface at the end of the inner race and the inner peripheral surface at the end of the outer race,
• the support member being fixed to the inner peripheral surface at the end of the outer race,
• the seal member having three seal lips, including an inner seal lip, an intermediate seal lip and an outer seal lip, made of resilient material and a portion connected and fixed to the support member,
• the outer seal lip of the seal member being located at the outermost location in the three seal lips, the inner seal lip being located at the innermost location in the three seal lips and an intermediate seal lip being located adjacent to the inner seal lip on the axially outer side thereof,
• the outer peripheral surface at the end of the inner race supporting a member which is formed in a generally annular ring shape having an L-shaped cross section, a radially cylindrical portion fitted to the outer peripheral surface of the inner race, and an outer circular ring portion being bent in the radial direction from the edge at the axially outer end of the radially cylindrical portion,
• the radially cylindrical portion having a radially oriented peripheral surface, the inner seal lip and intermediate seal lip having a tip edge which comes into sliding contact with the radially oriented peripheral surface and the outer seal lip having a tip edge which comes into sliding contact with an inner surface of the outer circular ring portion,
• wherein the radially oriented peripheral surface has an outer diameter of about 40 mm to 70 mm,
• wherein, provided that d1 is the thickness of the tip edge of the intermediate seal lip, that d2 is the thickness of the base end of the intermediate seal lip, that D1 is the thickness of the tip edge of the inner seal lip, that D2 is the thickness of the base end of the inner seal lip, the relations in thickness of 0.2·d1≦d2≦0.8·d1 and of 0.5·D1≦D2<D1 are satisfied in at least a portion of the base end of the intermediate seal lip and inner seal lip,
• wherein the inner seal lip experiences no or slight resilient deformation with substantially zero interference when the tip edge of the inner seal lip and intermediate seal lip comes into sliding contact with the radially oriented peripheral surface.