| 摘要 |
PROBLEM TO BE SOLVED: To ensure circularity of a bearing by projecting a plurality of ribs from the opposite sides, on the outer surface of a housing corresponding to the bearing, along the second diametral line of the housing in the direction orthogonal to the first diametral line and projecting a plurality of ribs on the side opposite to a coupler part along the first diametral line. SOLUTION: A coupler part 18c and a fourth rib 54 project from one side of a housing 18 at a part corresponding to a bearing 19 along the first diametral line L1 of the housing 18 and a plurality of first and second ribs 51, 52 project from the opposite sides along the second diametral line L2 of the housing 18 in the direction orthogonal to the first diametral line L1. Furthermore, a plurality of third ribs 53 project from the side opposite to the coupler part 18c along the first diametral line L1. Contraction of the housing 18 is suppressed as much as possible at the part corresponding to a bearing 19 by means of the coupler part 18c and the first throughfourth ribs 51-54 and the need of a jig for preventing deformation of the bearing 19 is eliminated thus sustaining circularity while preventing increase of labor. |
