| 摘要 |
PROBLEM TO BE SOLVED: To provide an injection-molded plastic gear capable of securing high rigidity permitting smooth power transmission, and sufficiently coping with demand of recent years for reduction of noise. SOLUTION: Cavity portions 7 for thinning a thickness of tooth 2 are formed at both end sides in the tooth width direction of the tooth 2 by a prescribed depth L1 from side faces 5, 6 of the tooth 2 toward the tooth width direction, and a tooth thickness of the parts provided with the cavity portions 7 is thickened in comparison with a tooth thickness of a part free from the cavity portion 7, by differenceδin contraction after injection molding. The injection-molded plastic gear 1 is flexibly deformed in being engaged with the other gear at the parts provided with the cavity portions 7 to absorb impact shock in an initial period of the engagement with the other gear, thus the generation of noise can be reduced. Further when the teeth 2 of the injection-molded plastic gear 1 are deformed until the tooth thickness of the parts with the cavity portions 7 becomes equal to the tooth thickness of the part free from the cavity portion 7, the part of high rigidity free from the cavity portion 7 transmits high rotating torque. COPYRIGHT: (C)2007,JPO&INPIT |
