Gas Leakage from Piston-Ring of Small Out-put Diesel Engine

A small out-put industrial diesel engine was used and the conditions of its piston-rings were changed, for the study of phenomena on the piston-ring leakage. And the following conclusions were obtained mainly : (1) Leakage occurs at three passages which are the clearance spaces at the lower, outer side and gap of the ring. And the rates of leakage through each passage are nearly equal when these passages are of the similiar shape and size. (2) Angle and step joint cannot reduce the increase of the leakage as same as straight joint when the gap is enlarged. (3) When rings of the good and bad tightness are used together, the good ring only makes the gas-tight. (4) the greater part of the gas that leakes out is air, and it is believed that the harmfully incomplete combustion products are caused by combustion of the oils on the gas passages. (5) For reducing the specific fuel consumption, a smaller number of rings of good-tightness must be used.