Patent ID: 7448806

Claim:
A rotation support device for a compressor pulley comprising: a rotatable shaft of a compressor; a stationary supporting member located round the rotatable shaft; a rolling bearing supported by the supporting member; and the pulley rotationally supported around the supporting member by the rolling bearing for entraining an endless belt therearound; the rolling bearing being provided with one of a first combination of an inner race having an inner raceway whose outer peripheral surface is shaped to come in contact with a rolling contact surface of a ball at one point and an outer race having an outer raceway whose inner peripheral surface is shaped to come in contact with the rolling contact surface of the ball at two points, and a second combination of an inner race having an inner raceway whose outer peripheral surface is shaped to come in contact with a rolling contact surface of a ball at two points and an outer race having an outer raceway whose inner peripheral surface is shaped to come in contact with the rolling contact surface of the ball at one point, the ball rollingly supported between the inner raceway and the outer raceway, the rolling bearing being a single-row three-point contact type radial ball bearing, wherein the cross sectional profile of the inner raceway other outer raceway which is in contact with the rolling contact surface of the ball at one point is formed in a composite arc by smoothly joining a plurality of arcs having different curvature radii in order that the curvature radius of the composite arc is small in the center side in the width direction while the curvature radius of the composite arc in the width direction is large near the opposite edges; and wherein a groove depth of one of the inner raceway and the outer raceway which is in contact with the rolling constant surface of the ball at two points is 18% to 40% of a diameter of the ball, and an offset amount in the axial direction between the center in the position in the width direction of the endless belt and the center position in the width direction of the radial ball bearing is up to 40% of the diameter of a pitch circle of the radial ball bearing.