Distal Lock Mechanism for Prosthetic Vacuum Suspension
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Solution Overview
Problem
Existing distal lock systems for prosthetic limbs, particularly those using vacuum suspension, fail to maintain a sealed environment, allowing air to leak into the hard socket and compromising the vacuum seal, which is undesirable during normal use or when significant vacuum is established.
Innovation Solution
A distal lock mechanism that connects the liner pin to the hard socket using a latch system with a cammed handle, preventing air flow through the lock mechanism by using a sliding shaft and blade design that biases the lock blade to engage the liner pin, ensuring a secure seal even under vacuum conditions, and allowing easy unlatching without radial pushing or pulling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional distal lock system is used to connect the liner to the hard socket, then the connection is achieved, but air leaks into the hard socket compromising the vacuum seal
Solution Approach 1:
The patent employs an elastomeric diaphragm as a flexible sealing element within the distal lock mechanism. This diaphragm forms a barrier that prevents air from passing through the lock mechanism into the hard socket, thereby maintaining the vacuum seal integrity while allowing the mechanical connection to function.
Solution Approach 2:
The patent introduces an intermediary sealing structure (the diaphragm and associated sealing surfaces) between the internal and external environments of the distal lock. This intermediary element mediates the connection between the liner pin and the hard socket while blocking the harmful air leakage path.
2Reliability
If a sealed distal lock mechanism is implemented to prevent air flow, then vacuum seal integrity is improved, but the complexity of the lock mechanism increases
Solution Approach 1:
The distal lock mechanism is designed to perform multiple functions: mechanical connection between liner and socket, prevention of air leakage through integrated sealing, and maintenance of vacuum pressure. By combining these functions into a single integrated assembly, the patent avoids the need for separate sealing components and mounting hardware, thereby reducing overall complexity.
Solution Approach 2:
The patent merges the sealing function with the mechanical locking function by integrating the elastomeric diaphragm directly into the lock mechanism housing and engagement surfaces. This consolidation eliminates the need for separate sealing gaskets or O-rings that would require additional installation steps and adjustment.
3Strength
If a vacuum pump is used to establish significant vacuum inside the socket, then suspension effectiveness is improved, but air leakage through the lock mechanism compromises the vacuum
Solution Approach 1:
The elastomeric diaphragm provides a flexible yet effective barrier that maintains its sealing properties under the pressure differential created by the vacuum pump. The flexibility of the elastomeric material allows it to conform to slight variations in the mechanical components while maintaining the vacuum seal, preventing air infiltration even under significant vacuum conditions.
4Ease of operation
If the lock mechanism is designed to be easily actuated by a lever system, then ease of operation is improved, but the sealing reliability may be compromised
Solution Approach 1:
The distal lock mechanism is segmented into distinct functional components: the lever actuation system, the blade engagement mechanism, and the diaphragm sealing system. This segmentation allows the sealing function to be independently optimized and protected from the mechanical stresses of actuation, maintaining seal integrity while enabling easy operation through the lever system.
Data Source
AI summary
A lock connects the distal end of a liner to the distal end of the hard socket of a prosthetic leg, and limits or prevents air flow into the hard socket through the distal lock mechanism, even when vacuum is established inside the socket. The distal lock normally is latched, but can be conveniently unlatched by swinging a cammed latch handle. The liner pin may be inserted and locked into the distal lock, without the distal lock being unlatched and without losing the internal air seal preventing air flow through passages of the lock. A slidable, biased lock blade, and interaction between slanted surfaces of the blade and the liner pin, allow the pin to slide down, but not up, past the blade. The latch handle does protrude radially outward a significant distance, when the lock is unlatched, but, as soon as the lock is latched, the handle resides against and/or near the outer surface of the lock housing.