Dynamic Anti-tip Wheel Assembly for Mobility Scooters

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Solution Overview

Problem

Existing anti-tip wheels on mobility scooters and powered wheelchairs can cause vehicles to become 'beached' when encountering obstacles like kerbs or slopes, leading to loss of traction and temporary loss of braking ability, which can result in difficulty moving the vehicle and potential accidents.

Innovation Solution

An anti-tip assembly featuring an idler wheel that engages with the driven ground-engaging wheels, allowing continued drive and braking by pivoting around a mounting point and utilizing a spring or biasing mechanism to return to its rest state, ensuring the vehicle remains operational over obstacles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If fixed anti-tip wheels are used to prevent vehicle toppling, then vehicle stability is improved, but the vehicle becomes prone to beaching and loss of traction

Engineering Contradiction:
Improvevehicle stabilityVSAvoidtraction reliability
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The anti-tip wheel assembly is made dynamic through a spring-biased mechanism that allows the anti-tip wheel to move between a retracted position (normal operation) and an engaged position (beaching prevention). The spring force enables the assembly to adapt to different terrain conditions, maintaining stability while preventing permanent beaching.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The anti-tip function is segmented from the main drive wheels through a separate mounted assembly. This segmentation allows the anti-tip mechanism to operate independently, engaging only when needed for stability, while the drive wheels maintain continuous ground contact for propulsion and braking.

Inventive Principle:
Principle #1Segmentation

2Stability of the object's composition

If anti-tip wheels contact the ground to prevent toppling, then vehicle stability is improved, but the vehicle becomes stuck and loses braking ability

Engineering Contradiction:
Improvevehicle stabilityVSAvoidvehicle maneuverability
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The spring-biased anti-tip assembly dynamically adjusts its position based on terrain conditions. During normal operation, the spring keeps the anti-tip wheel retracted, maintaining full maneuverability. When beaching occurs, the assembly naturally engages to provide stability, then can be disengaged to restore maneuverability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The spring mechanism provides self-service by automatically biasing the anti-tip assembly into the correct position based on terrain contact. The system self-regulates between engagement and disengagement states without external control, maintaining both stability and maneuverability as needed.

Inventive Principle:
Principle #25Self-service

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 anti-tip assembly maintains vehicle mobility and braking capability by transferring rotational and braking forces through the idler wheel, preventing beaching and ensuring continuous operation over various terrain features.

Implementation Method 1

utilizing a spring or biasing mechanism to return to its rest state

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

transferring rotational and braking forces through the idler wheel

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2211814B1Drivable Anti-tip castors
Publication Date: 2012.06.27 ADVANCED VEHICLE CONCEPTS
  • EP2211814B1 patent drawingFigure 1a~1d
  • EP2211814B1 patent drawingFigure 2a~3
  • EP2211814B1 patent drawingFigure 4~5b

AI summary

An anti-tip wheel (6) for a wheeled vehicle, particularly a mobility scooter, that is provided with means to drive it to prevent the vehicle from becoming beached upon its contact with the ground or an obstruction. The assembly containing the anti-tip wheel may pivot upon the anti-tip wheel's contact with an obstruction such that an idler wheel (8) held against the anti-tip wheel engages with a drive wheel (4) of the vehicle, such that the anti-tip wheel is driven by the drive wheel's motion, propelling the vehicle off the obstruction. Alternatively, the anti-tip wheel may be driven by a driveshaft, belt or have an independent motor.