Caster Wheel Lift-Off Switch for Wheelchair Tip Prevention
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Solution Overview
Problem
Powered mobility wheelchairs are prone to tipping, which poses safety risks due to their lightweight design and the inability of existing anti-tip solutions to effectively manage motor power and prevent momentum buildup before the wheelchair tips over.
Innovation Solution
A caster-wheel assembly with a switch-actuating mechanism that detects when the front wheels leave the ground, automatically disengaging motor power and engaging a braking system to prevent tipping, ensuring safety and stability by cutting power as soon as the wheels start to lift off the ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trailing anti-tip wheel is added to prevent tipping, then tipping prevention is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The patent extracts the tipping prevention function from a separate mechanical anti-tip device and integrates it into the existing caster wheel assembly through an electrical switch mechanism. This eliminates the need for additional trailing wheels and complex mechanical structures while maintaining safety functionality.
Solution Approach 2:
The patent replaces the mechanical anti-tip wheel system with an electrical control system. Instead of using a physical trailing wheel to prevent tipping, the invention uses a switch that detects wheel lift-off and electronically controls motor power, thereby substituting a complex mechanical system with a simpler electrical one.
2Reliability
If a trailing anti-tip wheel is added to prevent tipping, then tipping prevention is improved, but ease of operation deteriorates
Solution Approach 1:
The patent removes the cumbersome trailing anti-tip wheel structure that interferes with manual pushing and step navigation, retaining only the essential tipping prevention function through a compact switch mechanism integrated into the caster assembly.
3Productivity
If motor power is not cut when wheels leave ground, then vehicle propulsion is maintained, but safety deteriorates due to momentum buildup
Solution Approach 1:
The patent implements preliminary action by detecting the onset of wheel lift-off through the switch mechanism and preemptively cutting motor power before the vehicle can gain dangerous momentum. This prevents the harmful effect of continued motor torque during tipping rather than merely reacting after tipping has progressed.
Solution Approach 2:
The patent establishes a feedback loop where the switch detects the physical state of the caster wheels (on or off the ground) and automatically adjusts motor power accordingly. When wheels leave the ground, the switch signals the control system to reduce or cut power, creating a self-regulating safety mechanism that responds to actual vehicle conditions.
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 effectively prevents tipping by immediately reducing motor power and engaging a braking system when the wheels begin to lift, thereby reducing the risk of accidents and providing a safer user experience by addressing the momentum buildup issue.
Implementation Method 1
biasing means configured to provide a biasing force such that the wheel bracket is biased away from the housing
Data Source
AI summary
A caster-wheel assembly (100; 200) for a vehicle, for example a wheelchair or powered wheelchair. The caster-wheel assembly comprises a switch (13) coupled to a housing (3); a castering wheel bracket (9) configured to receive a wheel (10), wherein the bracket is rotatably mounted about a caster pivot axis (28) with respect to the housing; biasing means (15) configured to provide a biasing force such that the wheel bracket is biased away from the housing; and a switch-actuating member (13) coupled to the wheel bracket such that movement of the wheel bracket towards the housing and against the biasing force causes the switch-actuating member to actuate the switch.