Electro-hydrostatic actuator
First Claim
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1. An electro-hydrostatic linear actuator that includes:
- a sealed housing mounted upon a base, said housing containing a reservoir for filling the interior of the housing with a dielectric fluid;
a motor having a rotor shaft that is connected to a pump;
said motor and said pump being immersed in said fluid reservoir so that said pump can draw fluid from said reservoir;
a hydraulic cylinder located outside of said housing that contains a piston attached to a piston rod that passes out of said cylinder, said piston dividing the cylinder in a first chamber and a second chamber;
means for biasing said piston rod into a home position;
a supply line for connecting the pump outlet to one of said chambers;
and a controller immersed in said fluid that contains circuitry for controlling said motor such that the pump raises the fluid pressure in said one chamber to move the piston rod to a selected operative position.
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Abstract
An electro-hydrostatic actuator having a sealed housing filled with a dielectric fluid. A motor driven pump and electronics for controlling the pump are all immersed in the fluid. The pump is arranged to deliver fluid from the housing to a hydraulic cylinder to control the positioning of the piston rod. A solenoid operated valve is integrated as a bypass or tip valve for quick fail safe position. The actuator is ideally suited to control various types of plunger valves. In one embodiment of the invention, the hydraulic cylinder is located outside of the housing and in another embodiment the cylinder is located inside of the housing.
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Citations
22 Claims
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1. An electro-hydrostatic linear actuator that includes:
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a sealed housing mounted upon a base, said housing containing a reservoir for filling the interior of the housing with a dielectric fluid;
a motor having a rotor shaft that is connected to a pump;
said motor and said pump being immersed in said fluid reservoir so that said pump can draw fluid from said reservoir;
a hydraulic cylinder located outside of said housing that contains a piston attached to a piston rod that passes out of said cylinder, said piston dividing the cylinder in a first chamber and a second chamber;
means for biasing said piston rod into a home position;
a supply line for connecting the pump outlet to one of said chambers;
and a controller immersed in said fluid that contains circuitry for controlling said motor such that the pump raises the fluid pressure in said one chamber to move the piston rod to a selected operative position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An electro-hydrostatic actuator that includes:
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a hermetically sealed housing having a base section, said housing containing a fluid reservoir for filling the interior of the housing with a dielectric oil;
a brushless motor mounted in a first compartment in said base section of the housing, said motor having a rotor shaft that extends upwardly into said housing;
a first access cover removably mounted in said base section for closing the first compartment;
a pump connected to the rotor shaft of said motor for drawing fluid from said reservoir and delivering the fluid at an elevated pressure to a supply line;
a hydraulic cylinder mounted in a second compartment in said base section of said housing adjacent said first compartment;
a second access cover removably mounted in said base section for closing the second compartment;
said cylinder having a piston mounted therein for dividing the cylinder into a first chamber and a second chamber and a piston rod connected to said piston, said piston rod passing out of said cylinder through said second access cover;
means for biasing said piston rod into a home position;
said supply line being connected into one of the cylinder chambers to providing fluid under pressure to said chamber; and
a controller being immersed in said fluid reservoir in the upper part of the housing that contains circuitry for controlling said motor such that the pump raises the pressure in said one chamber to move the piston rod to a selected operative position. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification