To prevent the surface area of a cam face from being reduced by preventing a narrow part between a lift face and a base circle face from being fused by high heat during induction hardening.
This cam structure comprises a drive shaft 13 rotatingly driven by a crankshaft and having a drive cam 15 on its outer periphery and a rocking cam 17 to which a rocking force is transmitted from the drive cam through a rocker arm 23 and opening and closing an intake valve 2 by the rocking force. Both side parts 30a and 30b of the narrow part 29 formed between the base circle face 22a and the lift face 22b of a cam face 22 formed on the lower surface of the rocking cam are formed in a smooth circular arc shape gradually from the lift face to the base circle face to dissipate corner parts easily molten by high heat.
Hiromichi Kobayashi
Tomioka Kiyoshi