Linear actuator for asymmetric power generation and dissipation

Patent metadata

Field	Value
Publication number	US-11213408-B2
Application number	US-202117144418-A
Country	US
Kind code	B2
Filing date	Jan 8, 2021
Priority date	Jan 13, 2017
Publication date	Jan 4, 2022
Grant date	Jan 4, 2022

Abstract

An asymmetric linear actuator is provided which integrates a hydraulic dissipater and an electric motor and power screw which generates small forces. The actuator is configured so that an electric motor drives a power screw which drives a rod through a cylinder to provide linear actuation. The cylinder is fluid-filled and incorporates a piston that separates the cylinder into a first and second fluid chamber which are filled with a first and second volume of working fluid. Movement of the piston and rod assembly results in fluid movement between the first and second volumes of working fluid and through the fluidic restriction. The fluidic restriction can be proportionally controllable via an electric motor which enables controllable power dissipation via control of the fluidic restriction motor and controllable power generation via control of the power screw motor.

First claim

What is claimed is:

1. An actuator for exerting a controllable force between a first and second attachment point, comprising:
an actuator body;
a piston assembly;
a power screw assembly connecting the actuator body to the piston assembly;
wherein the actuator body includes a cylinder bore configured for holding a working fluid, the cylinder bore having a first cylinder end and second cylinder end, wherein the piston assembly includes a piston that slides linearly within the cylinder bore and a piston rod that extends from the piston through the second cylinder end to a piston rod end, which is located outside the actuator body, wherein the actuator body includes a first attachment point affixed to the actuator body and a second attachment point affixed to the piston rod end;
wherein the power screw assembly comprises a power screw connected to the actuator body to allow rotation and prevent translation, a power screw nut affixed to the piston assembly, and a first rotary motor disposed in the actuator body and configured to drive the power screw assembly;
wherein the piston assembly divides the cylinder bore into a first volume of the working fluid and a second volume of the working fluid,
wherein sliding of the piston causes rotation of the power screw and first motor,
wherein the actuator further comprises a first fluid port and a second fluid port, the first fluid port allowing fluid to enter or leave the first volume of the working fluid, the second fluid port allowing fluid to enter or leave the second volume of the working fluid,
wherein the first and second fluid ports are connected exclusively via at least one fluidic restriction.

2. The actuator of claim 1 , wherein the actuator further comprises:
a hydraulic accumulator in fluid communication with at least one of the first volume of working fluid and the second volume of working fluid.

3. The actuator of claim 1 , configured within an ankle prosthesis, further comprising:
a first leg member and second leg member, wherein the first and second leg members are rotationally coupled at the ankle joint and the first and second attachment points of the actuator are connected between the first and second leg members.

4. The actuator of claim 1 , configured within a knee prosthesis, further comprising:
a first leg member and second leg member, wherein the first and second leg members are rotationally coupled at the knee joint and the first and second attachment points of the actuator are connected between the first and second leg members.

Assignees

• Univ Vanderbilt

Inventors

• Goldfarb Michael
• Bartlett Harrison
• Lawson Brian

Classifications

• F15B2015/1495

  with screw mechanism attached to the piston · CPC title

• A61F2/68 Primary

  Operating or control means · CPC title

• F15B2211/40515

  with variable throttles or orifices · CPC title

• F15B2015/206

  Combined actuation, e.g. electric and fluid actuated · CPC title

• F15B2211/212

  the pressure sources being accumulators · CPC title