Wheelchair Suspension Force Distribution for Curb Climbing

Solution Overview

Problem

Wheelchairs face difficulties in traversing obstacles such as curbs and inclines due to the limitations of their front and rear caster configurations, which can lead to tipping and instability.

Innovation Solution

A wheelchair suspension system that includes a frame, a drive assembly, a front caster pivot arm, and a spring and shock absorbing assembly, allowing for independent or selective coupling to enhance the vehicle's ability to overcome obstacles by applying force effectively to the drive wheel and front caster.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the front casters are made smaller to improve stability, then the wheelchair becomes more stable, but the ability to traverse obstacles is reduced

Engineering Contradiction:

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The front caster assembly is segmented into a caster wheel, a pivot arm, and a suspension mechanism. This allows the caster to independently navigate obstacles while maintaining overall wheelchair stability through the suspension system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The front caster pivot arm is made movable rather than fixed, allowing it to pivot and adjust its position dynamically. This enables the caster to adapt to obstacles while the suspension system maintains stability during normal operation.

Inventive Principle:

Principle #15Dynamics

2Stability of the object's composition

If the suspension is made more rigid to prevent tipping, then stability is improved, but the suspension effectiveness is reduced

Engineering Contradiction:

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The suspension system uses adjustable parameters including spring stiffness, damper coefficients, and pivot point positions. These parameters can be optimized to provide sufficient rigidity for stability while maintaining enough flexibility to prevent tipping on inclines and obstacles.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If the suspension is made more flexible to improve obstacle traversal, then the ability to traverse obstacles is improved, but stabilization is compromised

Engineering Contradiction:

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The suspension system merges multiple functions into a single assembly: the spring provides flexibility for obstacle traversal, the damper provides stabilization, and the pivot arm provides both suspension and steering capability. This combination achieves both flexibility and stabilization simultaneously.

Inventive Principle:

Principle #5Merging (Combining)

4Adaptability or versatility

If the casters are made larger to improve obstacle traversal, then the ability to traverse obstacles is improved, but the stability is reduced

Engineering Contradiction:

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The suspension mechanism acts as an intermediary between the larger front casters and the wheelchair frame. It absorbs the instability generated by large casters while maintaining their obstacle-traversing capability, transmitting only smoothed forces to the frame.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 system improves the wheelchair's ability to traverse obstacles and maintain stability by distributing force effectively, reducing tipping and enhancing ride quality.

Implementation Method 1

a spring and shock absorbing assembly pivotally connected between the drive assembly pivot arm and the front caster pivot arm

Methodology Applied

Scientific EffectShock absorption: Damping

Implementation Method 2

a spring and shock absorbing assembly pivotally connected between the drive assembly pivot arm and the front caster pivot arm

Methodology Applied

Scientific EffectSpring mechanism: Spring

Data Source

PatentUS11234875B2Wheelchair suspension

Publication Date: 2022.02.01

AI summary

A wheelchair suspension includes a frame, a drive assembly pivot arm, a drive assembly, a front caster pivot arm, a front caster, and a spring and shock absorbing assembly. The drive assembly pivot arm is pivotally connected to the frame. The drive assembly includes a drive wheel and is mounted to the drive assembly pivot arm. The front caster pivot arm is pivotally mounted to the frame and coupled to the drive assembly pivot arm. The front caster is coupled to the at least one front caster pivot arm. The spring and shock absorbing assembly is pivotally connected to the drive assembly pivot arm at a first pivotal connection and pivotally connected to the front caster pivot arm at a second pivotal connection. The first and second pivotal connections are positioned such that a majority of the force applied by the spring and shock absorbing assembly is applied to the drive wheel when the suspension is on a flat, horizontal support surface.