Seal member for rolling bearing and rolling bearing assembly

A seal member for a rolling bearing, the rolling bearing having a pair of inner rings fitted on a rotational shaft in such a state that axial end portions abut against each other, an outer ring disposed radially outwards of the pair of inner rings, and an annular groove provided on an outer circumference of a portion where the end portions of the pair of inner rings abut against each other,

• wherein the seal member comprises an annular elastic portion made of an elastic material,
• wherein the seal member is mounted in the annular groove,
• wherein the elastic portion includes:
• an annular proximal end portion that is fixed to one axial end side of the annular groove;
• and
• an annular extending portion extending from the proximal end portion towards another axial end side of the annular groove, and having on an inner circumference thereof a sliding contact lip configured to be brought into sliding contact with the other axial end side of the annular groove,
• wherein the extending portion includes:
• a thin portion whose radial thickness is smaller than that of the proximal end portion along a circumferential direction, and which deforms radially outwards by virtue of a negative pressure generated in an interior of the rolling bearing to possibly cause the sliding contact lip to separate from the annular groove;
• and
• a thick portion whose radial thickness is greater than that of the thin portion, and
• wherein the thin portion and the thick portion are disposed alternately.