Eccentric Pin Joint for Prosthetic Limb Noise Reduction
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Solution Overview
Problem
Conventional articulating connections in prosthetic and orthotic devices experience undesirable wear and noise due to cyclical loading and clearance issues between pins and bushings, leading to increased manufacturing costs and reduced wear life.
Innovation Solution
An articulating connection system with a spring-loaded pin that eccentrically aligns and maintains continuous contact between the pin and bushing, reducing impact loading and noise through a preloaded condition that ensures constant surface contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If clearance is increased between pin and bushing, then ease of manufacture and assembly is improved, but noise and wear during operation increase
Solution Approach 1:
The spring applies a preliminary force to the pin, pre-positioning it to maintain continuous contact with the bushing bearing surface. This preliminary action ensures that during cyclical loading, the pin remains eccentrically aligned and prevents impact between the pin and bushing, thereby eliminating noise while allowing larger clearance for easier manufacture.
2Ease of manufacture
If clearance is increased between pin and bushing, then ease of manufacture is improved, but wear of interacting members increases
Solution Approach 1:
The spring applies a preliminary force to the pin, pre-positioning it to maintain continuous contact with the bushing bearing surface. This preliminary action ensures that during cyclical loading, the pin remains eccentrically aligned and prevents impact between the pin and bushing, thereby reducing wear while allowing larger clearance for easier manufacture.
3Object-generated harmful factors
If clearance is decreased between pin and bushing, then noise and wear are reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The spring acts as an intermediary element between the pin and the external forces. It applies a continuous preliminary force to the pin, maintaining its eccentric alignment and continuous contact with the bushing. This intermediary spring allows the use of larger clearance (simpler manufacturing) while still achieving the goal of reduced noise and wear through maintained surface contact.
4Object-generated harmful factors
If clearance is decreased between pin and bushing, then noise and wear are reduced, but risk of seizing increases
Solution Approach 1:
The spring applies a preliminary force to the pin, pre-positioning it to maintain continuous contact with the bushing bearing surface. This preliminary action ensures that during cyclical loading, the pin remains eccentrically aligned and prevents impact between the pin and bushing, thereby eliminating noise while allowing larger clearance for easier manufacture.
Solution Approach 2:
The design creates an asymmetric force distribution where the spring applies a unidirectional preliminary force to the pin, causing it to rest against one side of the bushing. This asymmetric pre-loading ensures continuous contact during operation while maintaining larger clearance, preventing both noise and seizing risk.
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 solution significantly reduces noise generation and increases the wear life of the articulating connection components while allowing for greater manufacturing flexibility and reduced friction, thereby improving the performance and durability of prosthetic and orthotic devices.
Implementation Method 1
at least one spring member disposed about at least a portion of the load bearing pin and at least a portion of the bushing, the at least one spring member configured to apply a preload to the load bearing pin
Implementation Method 2
The preloaded condition reduces the friction between the pin and bushing
Data Source
AI summary
An articulating connection or joint for a limb support device having a first support member and a second support member pivotably couples together the first support member and the second support member. The articulating connection can include one or more first articulating connection member, or load-bearing pin, and one or more second articulating connection member, or bushing, disposed about the first and second support members. The load-bearing pin is coupled to one of the support members and the bushing is coupled to another of the support members. The bushing is configured to rotatingly receive the load-bearing pin and interacts with an actuation member configured to apply a force on the load-bearing pin to eccentrically align the load-bearing pin relative to the bushing so that the load-bearing pin continuously follows and contacts a bearing surface of the bushing during use of the limb support device, thereby inhibiting noise generation from the interaction of the bushing and load-bearing pin.