Asymmetric Linear Actuator With Hydraulic Dissipation and High-Force Locking
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Solution Overview
Problem
Conventional actuators are symmetric in power generation and dissipation, making them inefficient for applications requiring high power dissipation at high forces and low power generation at low forces, leading to a need for a compact and lightweight actuator that can also lock at high forces.
Innovation Solution
A power-asymmetric actuator design incorporating a hydraulic cylinder with a piston assembly and two motors, where one motor drives a power screw for low-force power generation and the other controls fluidic restriction for high-force power dissipation and locking, with a hydraulic accumulator to manage fluid volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a standard power-symmetric actuator is used to meet large power dissipation requirements at high force magnitudes, then the actuator can dissipate large amounts of power, but the actuator becomes both large and heavy relative to the power generation requirements
Solution Approach 1:
The actuator is divided into two separate subsystems: a power generation subsystem with a first motor optimized for low-force generation, and a power dissipation subsystem with a second motor optimized for high-force dissipation. Each subsystem is independently sized and controlled, allowing the actuator to meet power dissipation requirements without oversizing the entire system for generation needs.
Solution Approach 2:
The patent implements asymmetric power handling by designing the actuator with different motor configurations for generation and dissipation modes. The first motor (generation) has different torque and speed characteristics than the second motor (dissipation), creating an asymmetric system that optimizes performance for each function rather than using a symmetric design for both.
2Power
If a standard power-symmetric actuator is used to meet large power dissipation requirements at high force magnitudes, then the actuator can dissipate large amounts of power, but the actuator becomes large relative to the power generation requirements
Solution Approach 1:
The actuator is divided into two separate subsystems: a power generation subsystem with a first motor optimized for low-force generation, and a power dissipation subsystem with a second motor optimized for high-force dissipation. Each subsystem is independently sized and controlled, allowing the actuator to meet power dissipation requirements without oversizing the entire system for generation needs.
3Weight of stationary object
If a power-asymmetric actuator design with two motors and hydraulic system is implemented, then the actuator achieves compact and lightweight structure, but the device complexity increases
Solution Approach 1:
The patent combines electric motor technology with hydraulic fluid dynamics in an integrated actuator system. The first and second motors work together with the hydraulic fluid volumes and compressibility to achieve both power generation and dissipation functions, merging multiple technologies into a unified compact system that reduces overall weight and volume.
Solution Approach 2:
The patent uses hydraulic fluid volumes trapped between the piston and cylinder ends to provide spring-like forces and energy storage. The compressibility of the hydraulic fluid enables passive force generation during retraction while the active motors provide controlled power for extension and dissipation, combining hydraulic principles with active motor control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The actuator achieves high power dissipation and locking capabilities while maintaining a compact and lightweight structure, suitable for applications like prosthetic joints that require asymmetric power handling.
Implementation Method 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
Implementation Method 2
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
Implementation Method 3
the first and second fluid ports being connected via a fluidic restriction, the fluidic restriction being an adjustable fluidic restriction controlled by a second motor
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
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.