Prosthesis Joint Wedging Clutch for Automatic Locking
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Solution Overview
Problem
Existing limb prostheses lack a compact and efficient mechanism to prevent the folding of the leg under the thigh, especially when weight transfer occurs, and to allow natural movement and stair climbing, while existing solutions are bulky and heavy.
Innovation Solution
An articulation mechanism with a wedging clutch and control wheel system that uses a tilting pallet and elastic linkages to automatically block and unlock the joint based on ground contact, allowing for adjustable locking and unlocking phases during walking and stair climbing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic locking cylinders or mechanical transmission devices are used to block the joint, then the joint can maintain angulation under torque, but the volume and weight of the prosthesis increase significantly
Solution Approach 1:
The patent extracts the essential locking function from complex hydraulic or mechanical systems and implements it through a simplified cable-rod mechanism that actuates a wedge-shaped locking element, removing unnecessary components while maintaining the core functionality of joint stabilization
Solution Approach 2:
The patent replaces complex hydraulic locking cylinders with a purely mechanical cable-rod actuation system that uses tension and wedge geometry to achieve locking, eliminating hydraulic components and reducing system complexity and weight
2Reliability
If hydraulic locking cylinders or mechanical transmission devices are used to block the joint, then the joint can maintain angulation under torque, but the volume of the prosthesis increases significantly
Solution Approach 1:
The patent extracts the essential locking function from complex hydraulic or mechanical systems and implements it through a simplified cable-rod mechanism that actuates a wedge-shaped locking element, removing unnecessary components while maintaining the core functionality of joint stabilization
Solution Approach 2:
The patent nests the locking mechanism components within each other, with the cable-rod system integrated into the existing joint structure and the wedge-shaped locking element positioned within the joint's natural geometry, minimizing additional volume
3Ease of operation
If a cable or rod actuated upon contact with the ground is used for mechanical transmission, then the locking can be achieved, but the device becomes more complex
Solution Approach 1:
The patent implements a self-actuating system where the cable-rod mechanism is automatically tensioned by ground contact forces during normal walking, eliminating the need for external actuators, sensors, or control systems while achieving automatic locking functionality
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 mechanism ensures the leg prosthesis remains stable and prevents unintended folding, enabling natural movement and stair climbing with a lightweight and compact design, improving user mobility and safety.
Implementation Method 1
one end of this link being fixed to the element secured to the leg by an elastic fixing acting on this link in the clutch release direction
Implementation Method 2
a compression spring interposed between the pallet and the body to continually tend to move the pallet away from the body
Implementation Method 3
the inner ring which comprises at least one peripheral surface facing the inner surface of the outer ring forming a wedge in which, under the effect of a spring, a roller or a ball is lodged and prevents any relative rotation of the rings in the direction of the thrust of the spring
Data Source
AI summary
The mechanism has an inner ring (6) and an outer ring (2) that are carried by an articulation piece (1) secured to a thigh of a subject. A control wheel indexing coupler i.e. cable (12), has an end that is fixed to a tilting tab (14) of another articulation piece (4) secured to a leg of the subject by a spindle drive tape roller (19) so as to allow supporting of a heel of a foot on a floor for folding the tab to block articulation of an orthosis and allow supporting of a tip of the foot on the floor for moving away the tab from the body to unblock articulation of the orthosis.