| 摘要 |
PROBLEM TO BE SOLVED: To enhance the mounting accuracy, heighten the mounting strength, and establish a lightweigt construction by equipping a crankshaft at its end with a rotary coupling part to couple the crank in the rotating direction, and furnishing at least behind it, an aligning part for generating alignment of the crank. SOLUTION: An aligning part 52 is provided at each end of a crankshaft 5 in such a tapered shape as thinning toward the end, wherein the taper angle is 2-3deg. At that end part still nearer the extremity than the aligning part 52, male serration 51 having eight teeth is provided, and the outside surfaces of the teeth constitute a surface continued to the periphery of the aligning part 52. The tooth form of serration 51 is square and the two flanks are approx. parallel, and rattling is not likely because the coupling force in the rotating direction is received by the plane approx. perpendicular to the force applied. Female threads 53 for crank fixation are furnished on the end face of the crankshaft 5, and because of hollow pipe shape, the central part has a still smaller wall thickness. The adopted material of aluminum contributes to lightweight construction along with the hollow structure. |
