| 摘要 |
<p>PURPOSE:To prevent core sand from falling outside of a camshaft and lubricant from intruding into the camshaft by casting the camshaft in the core sand into a hollow having openings at both ends thereof, and disposing a blind plug at the opening end on one side of the hollow while providing a camshaft driving means at the opening end on the other side, to be thus closed. CONSTITUTION:A camshaft 21 is cast in core sand contained into a hollow 22 having openings at both ends thereof. The camshaft 21 comprises a shaft portion having the hollow 22 and cam portions 21c formed on the outer periphery of the shaft portion. The hollow 22 is provided at the cam portions 21c with expanding portions 22c expanded outward. A metallic hard ball 24 is press-fitted to an opening end 22a on one side of the hollow 22, to be thus closed, where the hard ball 24 functions as a blind plug. A screw is formed at the inner circumferential surface of an opening end 22b on the other side of the hollow 22, where a timing belt pulley 3 as a camshaft driving means is fixingly screwed by a bolt 4. Consequently, it is possible to eliminate the possibility that the core sand falls outside during operation of an engine even if the core sand remains inside the hollow camshaft.</p> |
