| 摘要 |
PROBLEM TO BE SOLVED: To suppress vibration in operation and improve the durability. SOLUTION: Different material is used for the balls 13 of the second ball bearing 8 from those of the first ball bearing 7, which support a rotary shaft 2 on a bearing housing 6. Specifically, the material of the balls 13 of the second ball bearing 8 located on the side of an impeller 4 provides a larger linear expansion coefficient than that of the balls 13 of the first ball bearing 7 located on the side of a turbine 3. Such a construction reduces the contact angle of the second ball bearing 8 in operation and prevents the rolling contact surface of the balls 13 of the second ball bearing from running onto shoulders of the outer raceway and inner raceway, resulting in suppressed vibration and improved durability. |
