Practical Use of Two Piston Ring Set for Gasoline Engine
To obtain low friction engine through piston ring design, a set of two piston rings (two-ring set), one compression ring and one oil ring, has been recently developed. To reduce the number of compression rings from two to one, double angle step joint was employed for the shape of top ring gap, and taper face was introduced to O.D. surface shape. Major subjects of two-ring set were to reduce the oil consumption, to increase the durability, and to get the reliability of double angle step joint. The authors obtained the two piston ring design and the reliability of double angle step joint by rig tests and engine tests.