| 摘要 |
PROBLEM TO BE SOLVED: To securely bring a side rail in contact with a cylinder bore by the pushing force of each lug part of a spacer expander forming a combination oil ring. SOLUTION: A spacer expander 1 of a combination oil ring is provided with a projection 4 projected in a piston axial direction from a peripheral part 1a so as to support side rails 2 and 3, and a lug part 5 projected in the piston axial direction from an inner peripheral part 1b so as to push the side rails 2 and 3 outward in the radial direction. Since the lug part 5 is formed in the inner peripheral part 1b of the space expander 1 with a space by one or two waveform of the spacer expander 1, a distance between the adjacent lug parts 5 is larger in comparison with a lug part 5 of a conventional space expander 1, and the rigidity is relatively low. As a result, separate moving property of each lug part 5 is improved, and the dynamic influence between the adjacent lug parts 5 is reduced.
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