The Designs of Piston and Piston Ring to Reduce Lubricating Oil Flow into the Combustion Chamber

Using a modified engine with a transparent glass cylinder for motoring equipment, the effects of the structure in the vicinity of the oil ring groove drain back slots of the inside of the piston, the end clearance size of the oil ring side rail gaps and the shape of the top ring gap on the lubricating oil flow were examined.

The results indicate that the amount of undesirable oil flow was reduced by utilizing a piston with the covers installed under the drain back slots on the inside of the piston, the side rails with the optimized upper and lower side rail gap size and the top ring with a special joint (triangle step joint) as compared to a standard piston and standard piston rings. Furthermore, the amount of undesirable oil flow was considerably reduced by utilizing the combination of the modified piston and rings.