Patent ID: 11927243
Assignee: HITACHI ASTEMO, LTD.
Field: Mechanical elements (Mechanical engineering)
Classification: CPC F  B | IPC B  F

Claim 3:
4. A shock absorber comprising:
a cylinder that is filled with a working liquid;
a piston that is slidably fitted in the cylinder and divides an inside of the cylinder into two chambers;
a piston rod that is connected to the piston and extends to an outside of the cylinder;
a seal member that slidably contacts with the piston rod to prevent the working liquid from leaking from the cylinder to the outside;
a friction member that is provided further inside of the cylinder than the seal member, and is formed of an annular elastic rubber section which slidably contacts with the piston rod and an annular base section configured of a perforated disk-shaped bottom section, to which the elastic rubber section is fixed, and a tube section, which extends in the axial direction from an outer peripheral side of the bottom section and to which the elastic rubber section is fixed; and
a communication path that reduces pressure difference between both sides of the friction member in an axial direction,
wherein the elastic rubber section is provided with, on an inner peripheral side, a minimum inner diameter section, a first enlarged diameter section whose diameter is enlarged toward a side opposite to a cylinder inner chamber from the minimum inner diameter section, and a second enlarged diameter section whose diameter is enlarged toward the cylinder inner chamber from the minimum inner diameter section,
wherein the friction member applies a force to the piston rod such that movement of the piston rod in an outward direction of cylinder becomes difficult and the movement of the piston rod in an inward direction of the cylinder becomes easy,
wherein a first abutting surface, which abuts the piston rod, of the first enlarged diameter section of the elastic rubber section has a small frictional force, as compared with a second abutting surface, which abuts the piston rod, of the second enlarged diameter section, and
wherein the first abutting surface is formed of a coating layer having a smaller frictional force than the second abutting surface.