| 摘要 |
PROBLEM TO BE SOLVED: To provide a cylinder device capable of ensuring the sealability of a cup seal even when the pressure in a hydraulic fluid chamber is negative while ensuring the slidability of a piston.SOLUTION: A cup seal having a base part 10b abutted on a cylinder hole opening part sidewall 9g, an inner circumferential lip part 10c projected from an inner circumferential side of the base part 10b to a cylinder hole bottom part side, and abutted on an inner wall 9f, and an outer circumferential lip part 10a projected from an outer circumferential side of the base part 10b to a cylinder hole bottom part side, and abutted on a cylinder hole 3b, is attached to an annular seal groove consisting of the inner wall 9f formed in the outer circumferential direction of a piston 9, a cylinder hole bottom part sidewall 9h, and a cylinder hole opening part sidewall 9g. A cylinder hole bottom part sidewall 9111h of the seal groove has the outside diameter where the outer circumferential lip part 10a is abutted when the negative pressure is generated in a hydraulic fluid chamber 12. |
