Nsk Corporation

Yoshiaki Sakajiri

Hiromichi Takemura

Susumu Tanaka

Yuuki Tsuchida

A ball bearing has an inner ring fitted on a rotational shaft and including an inner ring raceway on an outer circumferential surface thereof, an outer ring including an outer ring raceway on an inner circumferential surface thereof, a plurality of balls rotatably provided between the inner ring raceway and the outer ring raceway and a crown resin cage for retaining the balls at equal intervals in a circumferential direction. A bore diameter of the inner ring is 100 mm or more, and a radial clearance resulting in a state that the inner ring is assembled to the rotational shaft is 20 &#x3bc;n or more.

Ball bearing and supporting construction

When a minimum thickness of a part where an outer ring raceway is provided on a middle portion in the axial direction of an outer ring is h, and a diameter of each rolling element is Da, the relationship 0.4 Da&#x2266;h 0.8 Da is satisfied. As a result, even when the outer ringis fixed in a transmission case of low-rigidity, elastic deformation of the outer ring can be prevented without needlessly increasing the thickness h of the outer ring. When an outer diameter of an outer ring is D, a width of this outer ring in the axial direction is W, a minimum thickness of a part where the outer ring raceway is provided on a middle portion in the axial direction of the outer ring is h, and a diameter of each ball is Da, the respective dimensions are controlled such that a value K calculated by {(h&#xb7;W)/(Da&#xb7;.D)} satisfies the relationship 1.20&#x2266;K&#x2266;2.00. As a result, sufficient rigidity of the outer ring can be maintained, and early exfoliation based on elastic deformation of the outer ring can be prevented without needlessly increasing the size of the outer ring.

Growing community of inventors

Kanagawa, Japan

Yoshiaki Sakajiri