Patent ID: 8985008
Filing Date: 2015-03-24
Classification: F16F,F16J

Abstract:
1. A cylinder apparatus comprising: an outer tube including a chamber which has a hydraulic fluid sealed therein, the outer tube having a first end and a second end that is spaced from the first end in the axial direction of the outer tube, the first end being open; a piston provided in the chamber of the outer tube; a piston rod connected to the piston and projecting out of the outer tube through the first end of the outer tube; an annular seal case provided in the outer tube at a position closer to the first end, the seal case having an inner peripheral portion and an outer peripheral portion; a first outer peripheral seal disposed between the outer tube and the outer peripheral portion of the seal case, the first outer peripheral seal sealing between the outer tube and the seal case; a second outer peripheral seal disposed between the outer tube and the outer peripheral portion of the seal case, the second outer peripheral seal sealing between the outer tube and the seal case; an annular rod seal provided at the inner peripheral portion of the seal case in sliding contact with the piston rod; and an annular oil seal provided at a side of the seal case that is closer to the first end, the annular oil seal being in sliding contact with the piston rod; the piston rod sealed in two stages by the rod seal and the oil seal, the outer peripheral portion of the seal case being provided with an outer peripheral groove and secured to the outer tube by a first staked portion formed by staking the outer tube from outside into the outer peripheral groove in a radial direction of the outer tube; and wherein the outer peripheral portion of the seal case receives at a side thereof closer to the chamber a pressure which is the same as a pressure applied to the rod seal, the outer peripheral portion of the seal case receives at an opposite side thereof spaced apart from the chamber a pressure between the rod seal and the oil seal which is reduced by the rod seal, the first outer peripheral seal is disposed at a first side of the first staked portion closer to the first end of the outer tube, the second outer peripheral seal is disposed at an axially opposite second side of the first staked portion closer to the second end of the outer tube, the first outer peripheral seal and the second outer peripheral seal are spaced apart from the first staked portion in the axial direction of the piston rod, the first outer peripheral seal is arranged to prevent the pressure between the rod seal and the oil seal, which is reduced by the rod seal, from being applied between the first staked portion of the outer tube and the outer peripheral portion of the seal case, and the second outer peripheral seal is arranged to prevent the pressure, which is the same as the pressure applied to the rod seal, from being applied between the first staked portion of the outer tube and the outer peripheral portion of the seal case.