| 摘要 |
PROBLEM TO BE SOLVED: To reduce noises and to secure sufficient strength in a rack assisting type electric power steering device. SOLUTION: The output of an electric motor is transmitted to a steering shaft through a speed reduction mechanism 22 including a small gear 30 and a large gear 31, and a ball screw mechanism. The teeth part 38 of the large gear 31 is formed of a synthetic resin material, and the teeth part 39 of the small gear 30 is formed of a metal material. Furthermore, the teeth part 38 of the large gear 31 is laterally displaced in a direction increasing dedendum thickness, and the teeth part 39 of the small gear 30 is laterally displaced in a direction decreasing the dedendum thickness. The impact of engagement between the small gear 30 and the large gear 31 is mitigated by the large gear 31 with the teeth part 38, thereby the noise of the speed reduction mechanism 22 is reduced. The arc dedendum thickness of the teeth part 38 of the large gear 31 is increased by the lateral displacement to further enhance the strength of the large gear 31. COPYRIGHT: (C)2005,JPO&NCIPI |
