초록 ▼

A hydraulic actuator comprising a pair of pressure oil chambers each of which has a cushioning port, the two cushioning ports being connected to each other through a cushioning means. The cushioning means includes a pair of cracking valves whose closing pressure is lower than its opening pressure an

A hydraulic actuator comprising a pair of pressure oil chambers each of which has a cushioning port, the two cushioning ports being connected to each other through a cushioning means. The cushioning means includes a pair of cracking valves whose closing pressure is lower than its opening pressure and a pair of restricting means for restricting the flow of a pressure oil provided with regard to said cracking valves. This structure permits an output means for the actuator to be stopped smoothly as a result of fully absorbing the inertial energy that accompanies the output means.

대표청구항 ▼

A hydraulic actuator comprising a main body, output means reciprocably disposed within said main body and first and second chambers defined by said output means within said main body, said first chamber having a first main port which is closed when said output means approaches one end of its stroke

A hydraulic actuator comprising a main body, output means reciprocably disposed within said main body and first and second chambers defined by said output means within said main body, said first chamber having a first main port which is closed when said output means approaches one end of its stroke and a first cushioning port disposed so that it remains open after said first main port has been closed, said second chamber having a second main port which is closed when said output means approaches the other end of its stroke and a second cushioning port disposed so that it remains open after said second main port has been closed, and said first and second main ports being connected by control valve means to a source of pressurized fluid including a reservior, cushioning means for connecting said first cushioning port and said second cushioning port to each other independently of said control valve means, and said cushioning means comprise a first cracking valve responsive to open at a first predetermined pressure and is responsive to close at a second predetermined pressure lower than said first predetermined pressure, first restricting means including a relief valve whose rated pressure is lower than the first predetermined pressure, said first restricting means, in series with said first cracking valve means which restricts the flow of pressurized fluid from said first cushioning port to said second cushioning port while said first cracking valve is open, a second cracking valve responsive to open when the pressure on the side of said second cushioning port reaches said first predetermined pressure and is responsive to close at a pressure lower than said first predetermined pressure, and a second restricting means including a relief valve whose rated pressure is lower than the first predetermined pressure, said restricting means in series with the said second cracking valve which restricts the flow of the fluid from said second cushioning port to said first cushioning port whiLe said second cracking valve is open.