Wheelchair Wheel Hub and Hand-Rim Coupling for Low-Clearance Braking
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Solution Overview
Problem
Existing wheelchair wheel systems suffer from clearance issues due to movable shaft portions, leading to reduced controllability and insecurity in braking, and require complex mounting solutions that involve adapting shafts and disassembling the entire system for replacement.
Innovation Solution
A wheelchair wheel system with a tubular element and freewheel clutch design that allows for a single main shaft to be used, reducing clearance and simplifying mounting by integrating the freewheel clutch, brake shoe, and blocking part through the tubular element, enabling easy assembly and disassembly without modifying the shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If two shaft portions are used with a coupling member movable in axial translation, then the wheel system can achieve forward motion and braking functions, but clearance and lost motion increase, reducing controllability
Solution Approach 1:
The patent merges two separate shaft portions into a single integrated shaft structure. The first shaft portion and second shaft portion are combined into one shaft that extends through the hub, eliminating the coupling member and reducing the number of moving parts. This integration directly reduces clearance and lost motion while maintaining the wheel system's ability to achieve forward motion and braking functions.
Solution Approach 2:
The single shaft structure serves multiple functions simultaneously: it supports the hand-rim extension portion, accommodates the freewheel clutch, and provides mounting for the blocking part. This multi-functional design eliminates the need for separate shaft portions and coupling mechanisms, reducing complexity while maintaining full operational capability.
2Ease of manufacture
If extension portion of hand-rim, inner ring of freewheel clutch and blocking part are mounted directly on shaft portions, then mounting is simplified, but shaft portions require adaptation with recesses, notches, flats
Solution Approach 1:
The patent combines the mounting functions for the extension portion, freewheel clutch, and blocking part into a single integrated shaft structure. Instead of requiring separate shaft portions with individual adaptations, the single shaft provides a unified mounting platform that reduces the overall number of adaptations needed while simplifying the mounting process.
Solution Approach 2:
The single shaft structure is designed to universally accommodate multiple components: the extension portion of the hand-rim, the inner ring of the freewheel clutch, and the blocking part. This universal mounting approach eliminates the need for multiple specialized shaft portions and their associated adaptations.
3Ease of repair
If distinct mounting solutions are selected for extension portion, inner ring of freewheel clutch and blocking part, then each element can be optimized, but the wheel system requires substantial disassembly for shaft replacement
Solution Approach 1:
The patent merges all mounting functions into a single shaft structure, which can be replaced as one unit. This eliminates the need to disassemble and replace multiple separate shaft portions and their associated mounting components, significantly simplifying the repair process while maintaining optimized mounting for each element.
4Ease of operation
If coupling member is movable in axial translation between first and second positions, then forward driving and braking are enabled, but angular travel and axial movement clearance increase
Solution Approach 1:
The patent extracts and eliminates the movable coupling member from the system. Instead of having a coupling member that translates axially between positions, the single shaft provides a fixed, stable mounting structure that eliminates clearance and lost motion while maintaining the ability to engage braking functions immediately through the integrated design.
Data Source
AI summary
Wheel system comprising a wheel having a hub with a main axis (X), the hub comprising an inner face with an inner conical surface; a tubular element; a main shaft inserted into the tubular element; a hand-rim comprising an extension portion having a threaded portion; a braking pad having a braking surface and a first conical surface; a coupling member translatably movable axially between a first position in which it rotatably links the hand-rim and the hub, and a second position for braking the hub; a freewheel arranged between the tubular element and the hub; and a blocking part for blocking the rotation of the tubular element relative to the frame.