Patent ID: 9352759
Filing Date: 2016-05-31
CPC Classification: B61F,F15B,Y10T

Claim Text:
1. A cylinder device comprising: a cylinder; a piston slidably inserted into the cylinder; a rod inserted into the cylinder and connected to the piston; a rod-side chamber and a piston-side chamber partitioned by the piston within the cylinder; a tank; a first on-off valve provided in the middle of a first passage allowing the rod-side chamber to communicate with the piston-side chamber; a second on-off valve provided in the middle of a second passage allowing the piston-side chamber to communicate with the tank; a pump for supplying liquid to the rod-side chamber; a discharge passage to connect the rod-side chamber to the tank; a variable relief valve capable of changing valve opening pressure, said variable relief valve being provided in the middle of the discharge passage; a suction passage permitting only the flow of liquid from the tank to the piston-side chamber; and a flow straightening passage permitting only the flow of liquid from the piston-side chamber to the rod-side chamber, said variable relief valve being composed of a solenoid variable relief valve capable of adjusting the valve opening pressure by a proportional solenoid, said variable relief valve including the proportional solenoid, a damping passage connected to the middle of the discharge passage, a relief passage juxtaposed with the damping passage, a selector valve element biased to open the damping passage and set to close the damping passage in current-carrying to the proportional solenoid, and a relief valve element biased to close the relief passage, the valve opening pressure of the relief valve element being reduced according to the current-carrying amount in the current-carrying to the proportional solenoid, the selector valve element providing a resistance to the flow of liquid when the damping passage is opened, wherein thrust is controlled by controlling the valve opening pressure of the variable relief valve.