Patent ID: 8857647

Claim:
A connecting structure which connects a first member and a second member, wherein: a first member comprises a connecting upright portion which is projected in a substantially cylindrical shape and comprises two or more groups of locking flanges whose locking forces vary, composed of a plurality of locking flanges provided to extend outwards along a circumferential direction of an outer side surface of the connecting upright portion; and a second member comprises a connecting side-wall portion which overlies said connecting upright portion and a plurality of locking projections provided to extend inwards from an inner side surface of the connecting side-wall portion, wherein said a plurality of locking flanges comprise no groove, and bottom faces thereof distend downwards in a convex curved shape and are continuously arranged so that a continuous track is formed along a circumferential direction of said connecting upright portion, and when said second member overlies said first member to be rotated, upper faces of said locking projections slide and contact with convex curved bottom faces of said locking flanges to be guided on said track and locked at a lowermost position of the convex curved bottom faces; wherein the locking flange is not held between two locking projections of the second member in a locked position; wherein a lower end of the locking projection is not in contact with the first member while the second member is rotating with respect to the first member, and wherein the plurality of locking flanges are provided in positional relationship to be reciprocally engageable with said locking projections, and each of the groups of locking flanges is continuously arranged so that all convex curved bottom faces form a continuous track along the circumferential direction of said connecting upright portion, and formed so that a dimension from an upper end surface of said connecting upright portion to the lowermost position of said convex curved bottom faces varies according to groups of locking flanges.