Prostheses with Externally Positioned Worm Mechanisms
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Solution Overview
Problem
Conventional hand prostheses with electromechanical components are cumbersome and unsuitable for children due to size constraints, particularly in providing powerful motors and suitable gear ratios for short prosthetic fingers.
Innovation Solution
The prosthesis design positions the worm mechanism outside the digit member, allowing for a more compact arrangement by relocating electromechanical components, including the drive motor, and utilizing a semi-circular worm gear wheel to reduce longitudinal space, enabling the creation of shorter digit members suitable for children.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the worm means is disposed within the digit member, then the transmission is compact, but the longitudinal space required within the digit member increases, making it unsuitable for short prosthetic fingers
Solution Approach 1:
The patent extracts the worm means from the digit member and positions it externally, allowing the digit member to be shorter while maintaining the necessary transmission functionality. This extraction resolves the space constraint within the digit member that previously prevented use in children with short fingers.
Solution Approach 2:
The patent repositions the worm means in a different spatial dimension - from inside the digit member to an external location where it engages with the worm gear wheel means. This dimensional change allows the transmission system to function without occupying longitudinal space within the digit member.
2Power
If powerful motors and suitable gear ratios are provided for short prosthetic fingers, then the prosthesis becomes more functional, but the size and complexity of electromechanical components increase
Solution Approach 1:
By extracting the worm means from the digit member, the patent creates space within the digit member to accommodate more powerful motors and larger gear components that were previously too large to fit, thereby enabling functional prostheses for children with short fingers.
3Reliability
If the prosthesis is designed for precise alignment between motor and transmission system, then the transmission efficiency is improved, but the arrangement becomes cumbersome and space requirements increase
Solution Approach 1:
The patent introduces the worm means as an intermediary component that engages with the worm gear wheel means. This intermediary allows for reliable power transmission while accommodating the external positioning of the motor, reducing the need for precise alignment between the motor and the final output.
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
This design results in a more compact and powerful prosthesis that can accommodate smaller digit members, such as those needed for children, while maintaining functionality and aesthetic appeal.
Implementation Method 1
a drive motor operable to drive a worm means
Implementation Method 2
The worm means being in engagement with the worm gear wheel means so that when the drive motor is operated, in use of the prosthesis, the digit member moves around the worm gear wheel means
Data Source
AI summary
A prosthesis (1) for providing at least one mechanically operable digit member. The prosthesis (1) has at least one digit member (3) extending generally tangentially with respect to a fixed worm gear wheel means (5) on a support member of the prosthesis and mounted for rotation about the worm gear wheel means axis (8). The digit member has a drive motor (7) operable to drive a worm means (13). The worm means (13) is in engagement with the worm gear wheel means (5) so that when the drive motor is operated, in use of the prosthesis, the digit member (3) moves around the worm gear wheel means (5), in which the worm means (13) is disposed outwith the digit member (3).