| 摘要 |
A cover member is to cover a cylinder and includes a plurality of peaks, a plurality of valleys, and coupling portions, which couple the plurality of peaks to the plurality of valleys. The cover member is expandable and contractable in an alignment direction in which the plurality of peaks and the plurality of valleys are aligned. Each peak of the plurality of peaks includes a depression depressed from an apex of the peak in a direction toward the cylinder, and each valley of the plurality of valleys includes a protrusion protruding from a bottom of the valley in a direction opposite to the cylinder. |
