To provide a cylinder capable of reducing friction and oil consumption by securing excellent oil retention performance without declining productivity.
A crosshatch angle formed on a bore face 7 of the cylinder 2 is set within a range of 10±5° over the entire bore face 7. Groove width is set ≤30 μm, and the number of grooves per unit length when the bore face 7 is cut along a piston moving direction is set ≥20 grooves/mm. Compared to the case where the crosshatch angle exceeds 15°, oil retention performance is improved and friction can be reduced. Since the number of grooves per unit length is set ≥20 grooves/mm, and the width of a groove 9 is narrowly set ≤30 μm , oil is continuously retained between a piston ring 4 and the bore face 7 during movement of the piston 7. Therefore, lubricating performance of the piston ring 4 is improved, and seizure can be prevented.
Miyazaki Yoshio
Kaoru Onozuka
Akio Tagami
High Masahiro
Toshio Nakamura
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