Vacuum-Assisted Prosthetic Suspension Pump Mechanism
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Solution Overview
Problem
Existing vacuum-assisted suspension systems in prosthetics face challenges in maintaining consistent negative air pressure due to incomplete compression cycles and air leakage, leading to inefficient attachment of prosthetic limbs.
Innovation Solution
A vacuum-assisted suspension system that utilizes a compression transfer element to increase and decrease the volume of a fluid chamber within the prosthetic socket, ensuring each pump cycle is fully utilized by expelling all fluid, thereby maintaining consistent negative pressure through a movable wall and spring element, and a tensioned cable mechanism to enhance the vacuum effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vacuum pump is used to create negative air pressure in the prosthetic socket, then attachment between the socket and residual limb is improved, but air leakage through the seal weakens the vacuum effect
Solution Approach 1:
The patent extracts the harmful air leakage problem by introducing a one-way valve that selectively blocks air from entering the socket while allowing the vacuum pump to remove air. The valve is positioned at the inlet to prevent backflow and maintain the vacuum seal integrity.
Solution Approach 2:
The one-way valve acts as an intermediary component between the external environment and the socket interior. It mediates the air flow by permitting extraction during pumping while preventing intrusion during vacuum maintenance, thus protecting the vacuum system from leakage.
2Productivity
If the pump is completely compressed to expel air in each cycle, then the pump capacity is maximized, but complete compression is difficult to achieve consistently with user gait
Solution Approach 1:
The spring element is pre-loaded to store potential energy before compression. When the pump is compressed during gait, the spring absorbs the compressive force and automatically returns the pump to its original position, ensuring complete expansion and air intake without requiring consistent user input.
Solution Approach 2:
The system converts the periodic compressive forces from natural gait into periodic pump cycles. Each step or heel strike provides a brief compression impulse, and the spring mechanism ensures that each impulse completes a full pump cycle (compression and expansion), maintaining consistent vacuum generation despite variable user input.
3Reliability
If the pump volume is increased to draw more air out, then vacuum creation is improved, but the pump size and weight increase
Solution Approach 1:
The pump chamber volume is made dynamic rather than static. The flexible diaphragm allows the chamber to expand and contract with each cycle, increasing the effective pumping volume during expansion without requiring a permanently larger pump housing. This dynamic volume adjustment maintains vacuum effectiveness while minimizing pump size and weight.
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 system achieves more efficient and consistent vacuum creation, reducing air pressure fluctuations, improving blood flow, wound healing, and providing better attachment between the socket and residual limb, resulting in a lighter and more stable prosthetic solution.
Implementation Method 1
The force applied on the first end of the compression transfer element causes the volume of the fluid chamber to increase via a second end of the compression transfer element connected to a movable wall of the fluid compartment
Implementation Method 2
A spring element which is compressed by the movable wall upon application of a compressive force and configured to expand in the absence of force on the movable wall to assist in expelling our out of the fluid compartment
Implementation Method 3
A suspension system usually relies on creating a vacuum or negative air pressure in the space between the socket and the surface of the residual limb
Data Source
AI summary
A vacuum assisted suspension system includes a prosthetic foot and a pump mechanism connected to the foot and fluidly couplable to a prosthetic socket. The pump mechanism includes an elongate pivoting member rotatable relative to the prosthetic foot about a joint and including a distal recess. A piston is connected to the foot and is movably received in the recess. A fluid chamber is defined between the piston and the interior of the recess. When no weight is placed on the foot a volume of the fluid chamber is zero or near-zero and when weight of a user is placed on the prosthetic foot the pivoting member rotates away from the piston and expands the volume of the fluid chamber to draw fluid into the fluid chamber from the prosthetic socket.