Vacuum Suspension Pump Mechanism for Prosthetic Sockets
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Solution Overview
Problem
Conventional vacuum suspension systems for prosthetic sockets are cumbersome, difficult to use, and unreliable, leading to suboptimal suction control and increased risk of the prosthesis disconnecting during ambulation or weight-bearing activities.
Innovation Solution
A pump mechanism with separate fluid chambers that allows for independent regulation of air differential, enabling quick and reliable adjustment of suction levels, and can be placed at various locations relative to the socket, using pneumatic or hydraulic pressure to create vacuum pressure for air expulsion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional vacuum systems with valves are used to expel air from the socket, then air can be removed from the distal end area, but air trapped in other areas remains and suction strength is diminished
Solution Approach 1:
The pump mechanism is divided into two separate fluid chambers: a first fluid chamber for receiving pressurized fluid and a second fluid chamber for creating vacuum pressure. This segmentation allows each chamber to perform its specific function independently, with the first chamber generating mechanical expansion force and the second chamber creating the vacuum effect needed to expel air from all socket areas.
Solution Approach 2:
A compressible fluid (gas or liquid) acts as an intermediary between the pressurized fluid source and the socket interior. The pressurized fluid expands the first chamber, which mechanically expands the second chamber, creating vacuum pressure that draws air out of the socket through the valve assembly, effectively removing air from all areas.
2Reliability
If conventional vacuum pumps are used to create vacuum pressure, then suction can be maintained, but the pumps are large, heavy, and difficult to use
Solution Approach 1:
The system uses pneumatic or hydraulic pressure from an external source to expand the first fluid chamber, which in turn mechanically expands the second fluid chamber to create vacuum pressure. This eliminates the need for a heavy electric motor-driven vacuum pump, reducing weight while maintaining reliable suction through fluid pressure mechanisms.
Solution Approach 2:
The pump mechanism uses a compressible fluid to dynamically expand and contract the first chamber, which mechanically expands and contracts the second chamber. This dynamic volume change creates the vacuum effect needed for suction, allowing the system to be lightweight yet effective.
3Reliability
If a valve is used to allow air expulsion during weight-bearing activities, then suction can be maintained, but the valve expels air when the limb is pushed further into the socket
Solution Approach 1:
The valve assembly includes a check valve that responds to pressure differential changes. When the limb is pushed into the socket during weight-bearing activities, the increasing pressure automatically triggers the check valve to open and expel excess air, then closes to maintain suction when pressure normalizes. This automatic feedback mechanism eliminates the need for manual operation.
Solution Approach 2:
The pump mechanism and valve assembly work together as a self-regulating system. The check valve automatically opens to expel air when pressure increases during limb insertion, and automatically closes to maintain vacuum when pressure stabilizes, without requiring user intervention or complex control mechanisms.
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
Provides superior control over suction levels, reducing air leakage and discomfort, allowing for secure attachment of the prosthesis during use and improving user confidence by ensuring a consistent fit.
Implementation Method 1
An increase in volume of the first fluid chamber mechanically expands the second fluid chamber, which, in turn, creates a vacuum pressure in the second fluid chamber
Implementation Method 2
creates a vacuum pressure in the second fluid chamber. The resulting vacuum pressure can draw air out of the socket interior and into the pump mechanism
Data Source
AI summary
A vacuum suspension system includes a pump mechanism operatively connectable to a prosthetic socket. The pump mechanism has a first member and a second member. An inflatable bladder is disposed between the first and second members. A fluid chamber is located between the first and second members and fluidly separate from the inflatable bladder. Inflation of the inflatable bladder mechanically separates the first and second parts to create a vacuum pressure in the fluid chamber.