Wheelchair Lock Pin Assembly with Remote Actuator
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Solution Overview
Problem
Traditional wheelchair wheel lock systems fail to prevent automatic engagement of the lock-pin with the lock plate during mechanical or operational failures, causing the wheelchair wheel to become immovable, and the cables are prone to ferrule displacement leading to system failures.
Innovation Solution
A wheelchair wheel lock system with a remote actuator and lock-pin assembly that does not use biasing members to force engagement, featuring a lock-pin assembly with a cylindrical metal lock-pin and a secure cable configuration using Bowden cables with ferrules locked in place by a locknut, preventing undesired engagement and enhancing cable security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a biasing member (spring) is positioned near or directly against the lock-pin to urge engagement, then the reliability of wheel lock engagement is improved, but the harmlessness in case of failure deteriorates because the wheel lock will automatically engage and become immovable during system failures
Solution Approach 1:
The patent removes the biasing member (spring) from the lock-pin assembly entirely. Instead of having a spring positioned near or directly against the lock-pin to urge engagement, the lock-pin is left un-biased and can only be moved by deliberate user action through the cable actuation system. This extraction of the harmful biasing element eliminates the automatic engagement problem while maintaining reliable engagement through proper cable tensioning and positioning.
Solution Approach 2:
The patent applies preliminary anti-action by designing the lock-pin to resist unintended movement through its mechanical configuration and cable routing. The lock-pin is positioned and oriented such that it requires deliberate cable actuation to engage, and the cable system is designed to prevent accidental activation. This preliminary design prevents the harmful automatic engagement before it can occur during system failures.
2Ease of manufacture
If traditional cable constraints (clamps or brackets) are used to secure ferrules, then the ease of manufacture is improved, but the reliability deteriorates because ferrules often pull out of their openings causing system failure
Solution Approach 1:
The patent segments the cable assembly into distinct functional components: the cable itself, the ferrule, and a dedicated retention mechanism. By separating the ferrule retention function from the cable constraint function, the design allows for more reliable ferrule securing while maintaining manufacturing simplicity. The segmented approach enables independent optimization of each component's performance.
Solution Approach 2:
The patent introduces an intermediary retention mechanism (such as a retention clip or locking feature) that mediates between the ferrule and the cable assembly. This intermediary component provides reliable ferrule retention without requiring complex manufacturing processes, bridging the gap between ease of manufacture and reliability by adding a simple but effective retention element.
Data Source
AI summary
A wheelchair wheel lock system for a wheelchair having a wheel lock plate with a locking face. The system includes a control cable, a lock-pin, a remote actuator and a biasing member. The control cable operatively connects the lock-pin with the remote actuator. The lock-pin is positioned proximate the locking face and selectively engages and disengages with the locking face when urged by the actuator. The biasing member urges the lock-pin to disengage from the locking face.