Wheelchair Knee Support Assembly With Releasable Flexible Harness

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Solution Overview

Problem

Existing wheelchair knee supports are difficult to engage and unlock, especially for users with physical impairments, and suffer from padding wear and discomfort due to compression, leading to poor performance and discomfort.

Innovation Solution

A knee support assembly with a flexible harness system that includes releasable harness holders connected to a base bracket, allowing easy placement or removal of legs, and features a spring-loaded locking mechanism and adjustable tightness for comfort and ease of use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a rigid bracket structure with padding is used for knee support, then structural strength and support capability are improved, but the padding wears down and hardens over time causing discomfort and poor performance

Engineering Contradiction:
Improvestructural strengthVSAvoidperformance consistency
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent replaces the rigid bracket structure with a flexible harness made of elastic material that wraps around the user's leg. This flexible harness maintains structural support capability while avoiding the wear and hardening issues of rigid padding, as the elastic material naturally conforms and redistributes pressure without degrading in performance.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the material properties from rigid to elastic, allowing the knee support to dynamically adapt its shape and pressure distribution. The elastic harness can stretch and recoil to accommodate different leg positions and sizes, maintaining consistent performance without the degradation experienced by compressed padding.

Inventive Principle:
Principle #35Parameter changes

2Strength

If laterally rotated knee supports are used to provide support, then knee support capability is improved, but the seat width increases significantly

Engineering Contradiction:
Improveknee support capabilityVSAvoidseat width
Core Design Contradiction:
StrengthVSArea of stationary object

Solution Approach 1:

The patent employs a flexible harness that can dynamically adjust its configuration rather than relying on fixed lateral rotation. The harness can be easily folded or removed when not in use, allowing the seat width to be minimized while still providing full knee support capability when activated.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The knee support function is extracted as a separate, removable flexible harness that can be independently deployed or stored. This allows the main seat structure to maintain a compact width while the support mechanism can be added or removed as needed, avoiding the permanent width increase caused by laterally rotated rigid supports.

Inventive Principle:
Principle #2Taking out (Extraction)

3Stability of the object's composition

If a complex locking mechanism is used to secure knee supports, then stability is improved, but ease of operation deteriorates for users with physical impairments

Engineering Contradiction:
ImprovestabilityVSAvoidease of engagement
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The flexible harness is designed to be self-securing through simple elastic tension and friction-based retention. The elastic material naturally tightens around the leg and maintains its position without requiring complex locking mechanisms, allowing users with physical impairments to easily engage and secure the support themselves.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The flexible elastic harness uses material properties (elasticity and friction) rather than mechanical locking components to achieve stability. This eliminates complex locking mechanisms while maintaining secure attachment, as the elastic material continuously adapts to maintain optimal tension and grip on the user's leg.

Inventive Principle:
Principle #30Flexible shells and thin films

4Ease of operation

If padding is added over rigid brackets for comfort, then user comfort is improved, but the padding compresses and hardens over time causing discomfort

Engineering Contradiction:
Improveuser comfortVSAvoidcomfort consistency
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent replaces compressed padding with a flexible elastic harness that inherently provides comfort through its material properties. The elastic material naturally conforms to the user's leg shape and distributes pressure evenly without compressing or hardening over time, maintaining consistent comfort throughout the product lifecycle.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent transitions from a static padding system to a dynamic elastic system that can change its physical parameters (shape, tension, pressure distribution) in response to user movement and positioning. This allows the harness to maintain optimal comfort characteristics without the degradation experienced by compressed foam or cushioning materials.

Inventive Principle:
Principle #35Parameter changes

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 flexible harness system provides reduced load on the user's knees, easy handling, and self-alignment, ensuring comfort and ease of use, while accommodating different leg sizes and positions.

Implementation Method 1

The harness holder is releasably connected to the base bracket assembly, to enable moving the flexible harness to the side relative to the base bracket assembly

Methodology Applied
Scientific EffectSpring mechanism: Spring

Data Source

PatentEP4445890B1Knee support assembly for a wheelchair
Publication Date: 2025.10.01 PERMOBIL
  • EP4445890B1 patent drawingFigure 1~2
  • EP4445890B1 patent drawingFigure 3~5
  • EP4445890B1 patent drawingFigure 6

AI summary

A knee support assembly (1) for a wheelchair, comprising: a knee support (3) comprising: a base bracket assembly (3a) configured to be mounted to a wheelchair (21), a first harness holder (3b) having a lower portion connected to the base bracket assembly (3a) at a first lateral side of the base bracket assembly (3a), a second harness holder (3c) having a lower portion connected to the base bracket assembly (3a) at a second lateral side of the base bracket assembly (3a), a flexible harness (3d) connected to and extending between the first harness holder (3b) and the second harness holder (3c), wherein the flexible harness (3d) is arranged to provide knee support, wherein at least one of the first harness holder (3b) and the second harness holder (3c) is releasably connected to the base bracket assembly (3a), to enable moving the flexible harness to the side relative to the base bracket assembly (3a) and thereby allow placement or removal of a leg between the base bracket assembly (3a) and the flexible harness (3d).