| 摘要 |
PROBLEM TO BE SOLVED: To improve the connection strength of a plate member rotating and engaging a sun gear, a ring gear, and a member and corresponding gears without changing the design of peripheral parts. SOLUTION: The tooth 2a of a sun gear 2 is removed in a non-use end part, and an enlarged cylindrical face 2c continuos with an original cylindrical face 2b is formed. A boss part 8a which is fitted in the cylindrical face 2c and abuts an end face of the tooth 2a is provided on a plate member 8, and a fitting part between the sun gear 2 and the plate member 8 is performed welding 15 from a side remote from the boss part 8a. Melting depth L of the welding is in a scope that is exceeds a plate thickness (d) of the plate member 8 and does not exceed the fitting part of the boss part 8a. Even if fitting allowance of the sun gear 2 and the plate member 8 is increased by a size of the fitting part between the boss part 8a and the cylindrical face 2c and melting depth L is set to correspond to the demand connection strength between the sun gear 2 and the plate member 8, it does not exceed the fitting part of the boss part 8a, and fusion length (b) becomes equal to the melting depth L so that the fusion length (b) is increased and the connection strength between the sun gear 2 and the plate member 8 can be improved without relying on increase of the plate thickness (d) of the plate member and welding diameter D and changing the design of peripheral parts.
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