| 摘要 |
PROBLEM TO BE SOLVED: To provide a thin width two-piece-type combined oil ring having the superior oil scraping function. SOLUTION: This combined oil ring is composed of an oil ring 1 and an expander 2. The oil ring 1 has an approximately I-shaped cross section, and outer peripheral faces of outer rail parts 6, 7 are provided with sliding faces 8, 9 kept into contact with a cylinder wall face. An expander accommodation groove 13 formed on an inner peripheral face of the oil ring 1 has a rectangular cross section, and the expander 2 formed of an axially wave-formed annular plate material is fitted in the expander accommodation groove 13. The expander 2 is formed by shaping the plate material of rectangular cross section into the waveform in the plate thickness direction, and further shaping the same into a ring. As the expander accommodation groove 13 of the oil ring 1, not only the groove having the rectangular cross section, but also, for example, that having a trapezoidal cross section where upper and lower faces are expanded toward an inner periphery, while using the plate material having an approximately rhombic cross section for the expander 2, can be also used.
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