FIXING STRUCTURE FOR COIL YOKE

摘要

PROBLEM TO BE SOLVED: To prevent fluctuation of magnetic characteristics while ensuring them sealing effect by eliminating the need for press fitting a coil yoke into a housing without complicating the structure. SOLUTION: A metal seal member 15 being press fitted to the inside of a housing 1 at the intermediate diameter part 1C thereof comprises a tubular part 15A having outer circumferential surface being fitted tightly to the inner circumferential surface of intermediate diameter part 1C, a ring part 15B extending radially inward from the end part of tubular part 15A on the side of small diameter part 1A, a small tubular part 15C extending toward the worm wheel 6 side from the inner circumferential part of ring part 15B, and a leaf spring part 15D extending radially inward from the end part of small tubular part 15C. The leaf spring part 15D is brought into tight contact with the end face 9b of a coil yoke 9B. A spring force F is induced in the leaf spring part 15D being fitted tightly to the end face 9b of coil yoke 9B by adjusting the shape of ring part 15B and small tubular part 15C appropriately under no-load, thus energizing the coil yokes 9A, 9B toward the receiving face 1D side.