Elastomeric Prosthetic Pump for Air Expulsion
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Solution Overview
Problem
Prior prosthetic devices face issues with air expulsion, weight distribution, and fluid loss due to the location of relief valves and use of metal components, leading to noise, weight, and packaging limitations, as well as the need for batteries and complex assembly.
Innovation Solution
An air expulsion pumping system using elastomeric components with a valve housing and internal elastomeric spring member, featuring one-way valves and a central passageway for efficient air removal without physical fasteners, allowing for easy installation, replacement, and manufacture with few moving parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a relief valve is mounted in the outer socket away from the distal end, then the valve can be accessed for air expulsion, but the residual limb blocks the valve and prevents complete air expulsion
Solution Approach 1:
The valve is repositioned from a lateral position in the socket wall to a distal extension protruding from the end of the socket. This dimensional change allows the valve to be located at the most distal point of the socket, clear of the residual limb, enabling complete air expulsion while maintaining ease of operation through the extended valve structure
2Strength
If metal components are used in the pump assembly, then structural strength is achieved, but noise and weight increase
Solution Approach 1:
The material composition of the pump components is changed from metal to elastomeric material. This parameter change maintains the structural integrity needed for pump operation while eliminating the harmful effects of noise and excessive weight associated with metal components
Solution Approach 2:
The pump assembly utilizes elastomeric composite materials that combine flexibility, durability, and noise-dampening properties. The elastomeric pump housing and spring member provide the necessary structural strength while inherently reducing noise generation compared to traditional metal constructions
3Reliability
If a vacuum pump is attached to the upright assembly, then suction is created to hold the liner to the socket, but the system becomes more complex and heavier
Solution Approach 1:
The vacuum pump function is extracted from the upright assembly and integrated directly into the distal extension of the socket. This extraction simplifies the overall system by eliminating separate pump components and mounting structures, reducing complexity while maintaining the suction seal reliability needed to hold the liner to the socket
Solution Approach 2:
The pump mechanism is merged with the socket structure by integrating it into the distal extension. This combination consolidates multiple components into a single unified assembly, reducing the number of separate parts and simplifying the overall device while maintaining effective suction for securing the liner
4Reliability
If the residual limb volume decreases due to fluid loss, then the prosthesis fit deteriorates, but the amputee must remove the limb and don additional socks to compensate
Solution Approach 1:
The elastomeric spring member in the pump system provides a feedback mechanism that responds to changes in residual limb volume. As the limb volume decreases due to fluid loss, the spring member automatically adjusts its compression state, maintaining consistent suction pressure and prosthesis fit without requiring amputee intervention or additional socks
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 system ensures continuous total contact between the residual limb and socket, reduces fluid loss, and improves weight distribution by efficiently expelling air, eliminating the need for batteries and complex assembly, while being lightweight and quiet.
Implementation Method 1
an internal elastomeric spring member, the elastomeric spring member having upper and lower surfaces in sealing engagement with the internal surfaces of the pump housing
Implementation Method 2
Within the central passageway are first and second one-way valves; the first one-way valve being located upstream of the at least one lateral passageway, and the second one-way valve being located downstream of the at least one lateral passageway
Implementation Method 3
Mounted within the well is an air expulsion pump having a valve housing made of elastomeric components having outer surfaces complementally configured to the inside surfaces of the well such that the pump housing fits in sealing relationship within the distal extension
Data Source
AI summary
An air expulsion pump for a prosthetic socket adapted to be worn on a residual limb of an amputee. The pump includes an elastomeric housing which fits snugly in a well defined in the lower end of the socket. The pump is easy to install by simply sliding it into the well. The pump has an upper surface commensurate with the inside surface of the socket in that both surface have the same radius of curvature. The pump includes an elastomeric spring member and two check valves that together with the elastomeric housing exert a continuous vacuum within the prosthetic socket. When donned by the user, the pump provides continuous total contact between the socket and the residual limb of the user as the user ambulates.