SPACER EXPANDER OF COMBINATION OIL RING

摘要

PROBLEM TO BE SOLVED: To provide a spacer expander for combination oil ring capable of enhancing its lubrication effect with a side rail and thereby reducing wear of these parts. SOLUTION: The spacer expander 1 of the combination oil ring includes a pair of side rails 2 installed in ring grooves formed in a piston and is configured with a side rail pressing part for pressing the peripheral surfaces 8 of the side rails 2 to the inside surface 5 of a cylinder by pressing the inside surfaces of the side rails 2 and a trapezoidal side rail supporting part 9 for pressing the outside surface 7 in circumferential direction of each side rail 2 to the side face 11 of the ring groove, wherein the side rail supporting part 9 has a side rail holding point P which is positioned between 6% and 40% from the peripheral end face 10 of the side rail supporting part 9.