ELECTRIC POWER STEERING DEVICE AND MANUFACTURING METHOD FOR WORM WHEEL

摘要

PROBLEM TO BE SOLVED: To make a contact area of a worm and a tooth flank of a worm wheel relatively large, to educe a bearing pressure of the tooth flank and to enhance a durability. SOLUTION: A tooth part 7a of a worm wheel 7 in which at least tooth part 7a is made of synthetic resin is molded such that a tooth bottom surface 74 becomes a circular arc along an outer edge at a rotation area of a worm 6. A contact area can be made relatively larger and a bearing pressure of the tooth flank can be reduced by making a gap between the worm 6 and the tooth flank of a worm wheel 7 to an appropriate gap.