| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball bearing unit for a supercharger, of low frictional torque and low heat generation.SOLUTION: A ball bearing unit includes an outer ring composed of a single cylinder and having double row outer ring raceway surfaces, two inner rings having inner ring raceway surfaces respectively opposed to the double row outer ring raceway surfaces, balls of two rows rollable between the outer ring raceway surfaces and the inner ring raceway surfaces, and a cage for holding the balls at equal intervals in the circumferential direction. The outer ring is provided with a lubricant supply hole inclined to the radial direction of the outer ring toward the ball sides. As the balls of two rows are not preloaded, and are provided with positive gaps, the low frictional torque and low heat generation can be realized in a bearing operation. |
