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.
1. A cover member to cover an object and comprising:
a plurality of peaks;
a plurality of valleys; and
coupling portions coupling the plurality of peaks to the plurality of valleys,
wherein the cover member is expandable and contractable in an alignment direction in which the plurality of peaks and the plurality of valleys are aligned,
wherein each peak of the plurality of peaks comprises a depression depressed from an apex of the peak in a direction toward the object, and each valley of the plurality of valleys comprises a protrusion protruding from a bottom of the valley in a direction opposite to the object, each of the coupling portions being connected at the depression and the protrusion,
wherein the depression has a U-shape in a cross-section, and includes edges of two sides of the U-shape in the direction opposite to the object, and the protrusion has a reverse U-shape in a cross-section, and includes bases of the reverse U-shape in the direction toward the object,
wherein when the cover member contracts in the alignment direction, the depression of the peak is deformed to enlarge an opening of the depression large enough to make the adjacent edges of adjacent two of the peaks touch each other, and the protrusion of the valley is deformed to enlarge a reverse opening of the protrusion large enough to make the adjacent bases of the adjacent two of the valleys touch each other, and
wherein connection of the coupling portion to the depression and the protrusion is thicker than a thickness of the coupling portion in a direction perpendicular to an outer surface thereof.
2. The cover member according to claim 1 , wherein when the cover member contracts in the alignment direction, a width of the peak in the alignment direction is equal to a width of the valley in the alignment direction.
3. The cover member according to claim 1 , wherein when the cover member contracts in the alignment direction, the U-shaped depression deforms into an arcuate shaped depression defined by non-parallel side walls and the reverse U-shaped protrusion deforms into an arcuate shaped protrusion defined by non-parallel sides.
4. The cover member according to claim 3 , wherein the U-shaped depression deforms in a direction perpendicular to the U-shaped depression resulting in enlargement of an opening of the U-shaped depression and the reverse U-shaped protrusion deforms in a direction perpendicular to the reverse U-shaped protrusion resulting in enlargement of the bases of the reverse U-shaped protrusion.
5. The cover member according to claim 1 , wherein the U-shaped depression is defined by a pair of side walls having parallel inner surfaces in an expanded position of the cover member and the reverse U-shaped protrusion is defined by a pair of side walls having parallel inner surfaces in the expanded position of the cover member.
6. The cover member according to claim 1 , wherein in an expanded position of the cover member, adjacent coupling portions extend along axes that intersect one another at a point that is along a center axis that extends along an opening of one of the depression and the protrusion.
7. The cover member according to claim 1 , wherein the edges and the bases are formed to have a curved shape.
8. The cover member according to claim 1 , wherein the coupling portion has an outer surface that extends linearly.
9. A cover member to cover an object comprising:
a plurality of peaks;
a plurality of valleys; and
coupling portions coupling the plurality of peaks to the plurality of valleys,
wherein the cover member is expandable and contractable in an alignment direction in which the plurality of peaks and the plurality of valleys are aligned,
wherein each peak of the plurality of peaks comprises a depression depressed from an apex of the peak in a direction toward the object, and each valley of the plurality of valleys comprises a protrusion protruding from a bottom of the valley in a direction opposite to the object,
wherein the depression has a U-shape in a cross-section, and includes edges at two sides of the U-shape in the direction opposite to the object, and the protrusion has a reverse U-shape in a cross-section, and includes bases at two sides of the reverse U-shape in the direction toward the object,
wherein when the cover member contracts in the alignment direction, the adjacent edges of two adjacent peaks are in touch with each other, and the adjacent bases of two adjacent valleys are in touch with each other,
wherein the apex is formed at a portion where extensions of outer surfaces of two adjacent coupling portions meet,
wherein the bottom is formed at a portion where extensions of inner surfaces of two adjacent coupling portions meet, and
wherein the depression is connected to the coupling portion at a first connection portion, whose thickness is greater than a thickness of the coupling portion in a direction perpendicular to an outer surface thereof.
10. The cover member according to claim 9 , wherein the protrusion is connected to the coupling portion at a second connection portion, whose thickness is greater than the thickness of the coupling portion in the direction perpendicular to the outer surface thereof.