Space-constrained hybrid linear actuator
First Claim
1. An hybrid linear actuator comprising:
- a first drive assembly comprising;
an electric drive motor having an output shaft;
a drive screw attached to the output shaft;
a drive nut threaded to the drive screw; and
an output rod having two ends, a first end attached to the drive nut so that rotation of the drive screw advances or retracts the output rod, and the second end capable of attachment to a linear actuated valve;
a second drive assembly comprising;
an hydraulic cylinder,a piston disposed in the hydraulic cylinder and linked to the output rod, anda hydraulic pump fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on either side of the piston to thereby vary a position of the piston within the hydraulic cylinder to thereby extend and retract the output rod;
wherein the drive screw is disposed at least partially within the hydraulic cylinder and is of unitary construction; and
wherein the actuator has a third drive assembly comprising first and second hydraulic accumulators fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on at least one side of the piston and wherein the first and second hydraulic accumulators are configured to be charged by the electric motor.
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Abstract
An electric motor-driven, rolling element screw linear actuator is presented which work in cooperation with an hydraulic actuator and share several components. This is achieved through the integration of a screw-driven integrated nut piston assembly. Combining the use of an electric screw driven actuator can also reduce the need for a redundant hydraulic system, resulting in the elimination of 50% of connections, valves, piping, pumps, filters etc., while still being 100% redundant. An additional advantage is that the two drive systems are technologically independent, and therefore will not both fail because of an identical component flaw or failure point. The systems may also be used at the same time if conditions require force in excess of that generated by the hydraulic actuator alone.
13 Citations
20 Claims
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1. An hybrid linear actuator comprising:
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a first drive assembly comprising; an electric drive motor having an output shaft; a drive screw attached to the output shaft; a drive nut threaded to the drive screw; and an output rod having two ends, a first end attached to the drive nut so that rotation of the drive screw advances or retracts the output rod, and the second end capable of attachment to a linear actuated valve; a second drive assembly comprising; an hydraulic cylinder, a piston disposed in the hydraulic cylinder and linked to the output rod, and a hydraulic pump fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on either side of the piston to thereby vary a position of the piston within the hydraulic cylinder to thereby extend and retract the output rod; wherein the drive screw is disposed at least partially within the hydraulic cylinder and is of unitary construction; and wherein the actuator has a third drive assembly comprising first and second hydraulic accumulators fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on at least one side of the piston and wherein the first and second hydraulic accumulators are configured to be charged by the electric motor. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A compact hybrid linear actuator comprising:
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an hydraulic cylinder having an inner chamber, a proximal end and a distal end; an output rod extending from the distal end the hydraulic cylinder, the output rod having a proximal end and a distal end; a piston on the proximal end of the output rod, the piston being disposed within the inner chamber of the hydraulic cylinder; the piston dividing the inner chamber of the hydraulic cylinder into a first pressure chamber and a second pressure chamber; a nut disposed in the first pressure chamber of the hydraulic cylinder; the nut disposed in a fixed, non-rotatable relationship with respect to the output rod; a drive screw disposed in the first pressure chamber and installed into the nut such that rotation of the drive screw moves the output rod; and wherein the actuator comprises a third drive assembly comprising a first accumulator fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on a first side of the piston and a second accumulator fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on a second side of the piston and wherein the electric motor driven screw pushes the integrated nut piston, to create fluid flow and pressure into at least one of the first accumulator and the second accumulator configured to charge at least one of said first or second accumulator. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A linear actuator having redundant power sources for use in space constrained areas comprising:
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an output rod having a proximal end and a distal end; the output rod having a hollow passage way extending from its proximal end toward its distal end; a first drive assembly comprising; a drive nut disposed in a non-rotatable and fixed position with respect to the output rod, a drive screw installed into the drive nut such that the drive screw extends into the hollow passage way of the output rod, and an electric drive motor having an output shaft linked to the drive screw such that rotation of the output shaft rotates the drive screw to thereby extend and retract the output rod; a second drive assembly comprising; a hydraulic cylinder, a piston disposed in the hydraulic cylinder and linked to the output rod, and an hydraulic pump fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on either side of the piston to thereby vary a position of the piston within the hydraulic cylinder to thereby extend and retract the output rod; and a third drive assembly comprising; a first accumulator fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on a first side of the piston; and a second accumulator fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on a second side of the piston; and
wherein at least one of the first accumulator and second accumulator is configured to be charged by the electric motor. - View Dependent Claims (16)
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17. A compact hybrid linear actuator comprising:
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an output rod; a first drive assembly comprising; a drive nut linked to the output rod, a drive screw installed into the drive nut, an electric drive motor having an output shaft linked to the drive screw such that rotation of the output shaft rotates the drive screw to thereby extend and retract the output rod, and a second drive assembly comprising; an hydraulic cylinder, a piston disposed in the hydraulic cylinder and linked to the output rod, and an hydraulic pump fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on either side of the piston to thereby vary a position of the piston within the hydraulic cylinder to thereby extend and retract the output rod, wherein the first drive assembly and the second drive assembly are individually capable of extending and retracting the output rod if the other drive assembly fails; and wherein the output rod comprises a hollow interior, and wherein the drive screw extends into the hollow interior of the output rod; and a third drive assembly comprising; a first accumulator fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on a first side of the piston; and a second accumulator fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on a second side of the piston. - View Dependent Claims (18, 19, 20)
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Specification