Patent ID: 7325974

Claim:
A pulley rotation support apparatus, comprising a fixed support part, a rolling bearing supported on the fixed support part, and a pulley on which an endless belt is disposed: the rolling bearing being a single-row three-point- or four-point-contact radial ball bearing including an inner ring having an inner raceway on the outer peripheral surface thereof, the inner raceway contacting with the rolling surface of a rolling element at one or two points, an outer ring having an outer raceway on the inner peripheral surface thereof, the outer raceway contacting with the rolling surfaces of the rolling element at one or two points, a plurality of rolling elements rotatably interposed between the inner raceway and outer raceway, a retainer with pockets for holding the rolling elements therein, and a seal plate having the outer peripheral edge portion secured to the inner peripheral surface of the outer ring and a leading end portion of a seal lip formed in the inner peripheral edge portion thereof, the seal lip slidably contacting with the inner ring, wherein the rolling bearing is lubricated by a lubricant, and at least one of the inner raceway and outer raceway is contacted with the rolling surfaces of the rolling element at two points respectively, and wherein an offset quantity being an axial-direction distance between the width-direction central port ion position of the outer peripheral surface of the pulley to be contacted with the endless belt and the center of the radial ball bearing is 40% or less of the pitch circle diameter of the radial ball bearing, the radial clearance of the radial ball bearing in an unloaded state is 0.2% or less of the pitch circle diameter of the radial ball bearing, and the seal plate has, of the inner surfaces thereof, at least a portion adjacent the outside-diameter portion thereof close to the inner peripheral surface of the outer ring, the portion adjacent the outside-diameter portion is formed as an inclined surface or a concavely curved surface inclined inwardly in the axial direction as it goes outwardly in the diameter direction.