Wheelchair Cable Traction Drive with Angular Recovery Spring
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Solution Overview
Problem
Traditional wheelchairs require external assistance for propulsion and direction control, limiting user independence, especially in sports and social situations, and are prone to dirt accumulation and mobility issues due to the design of traction rings.
Innovation Solution
A wheelchair with an angular recovery spring and flexible tension element that allows users to operate the wheelchair through cable traction, enabling independent movement and direction control without increasing the overall dimensions or weight, and can be retrofitted onto existing models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional traction rings are used for wheelchair propulsion, then the wheelchair can be pushed by an accompanying person, but the user cannot maintain independence and social interaction is limited
Solution Approach 1:
The wheelchair propulsion system enables the user to propel and steer the wheelchair independently through self-service mechanisms. The user operates the wheelchair using arm levers that connect to the wheel axles, eliminating the need for an accompanying person and enabling independent mobility and social interaction.
2Productivity
If the user uses both arms to operate traditional traction rings, then the wheelchair can move in a straight line, but the user cannot hold objects or engage in social gestures
Solution Approach 1:
The wheelchair propulsion system enables the user to propel and steer the wheelchair independently through self-service mechanisms. The user operates the wheelchair using arm levers that connect to the wheel axles, eliminating the need for an accompanying person and enabling independent mobility and social interaction.
3Ease of operation
If traditional armrests are positioned far from the wheel axis, then the user has comfortable arm support, but the user cannot effectively propel the wheelchair
Solution Approach 1:
The armrest assembly is segmented into a support portion and a propulsion portion. The support portion provides comfortable arm support positioned away from the wheel axis, while the propulsion portion extends closer to the wheel axis to enable effective propulsion. This segmentation allows both comfort and effectiveness to coexist.
Solution Approach 2:
The armrest assembly is designed to be movable between a support position (far from wheel axis for comfort) and a propulsion position (closer to wheel axis for effectiveness). This dynamic repositioning allows the user to switch between comfortable support and effective propulsion as needed.
4Ease of operation
If a cable traction system is implemented, then user independence and speed are improved, but the overall dimensions and weight may increase
Solution Approach 1:
The arm lever assembly serves multiple functions: it provides structural support as part of the wheelchair frame, acts as a lever for propulsion, and connects to the cable traction system. This multi-functionality reduces the need for separate components, thereby minimizing weight increase while maintaining independence and speed benefits.
Solution Approach 2:
The cable traction system uses flexible cables instead of rigid mechanical linkages. These cables can be routed through the existing wheelchair frame structure without requiring additional heavy support components, thereby minimizing weight increase while enabling independent propulsion and steering.
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
Enhances user independence and speed in sports activities while maintaining compactness and portability, allowing users to navigate various terrains and perform precise directional changes without external help.
Implementation Method 1
a recovery spring (M) acting on the recovery pulley (12) and the hub (16) are coaxial
Implementation Method 2
the flexible tension element rewinds for a variable working angle, which has a value maximum of one revolution, around the recovery pulley
Implementation Method 3
a cable (9) tensioned by the user in a reciprocating way to advance the wheelchair (1)
Implementation Method 4
a freewheel (14) for connecting the pulley (12) to interface unit (13) and allowing traction of the traction wheels (4) through the interface unit (13) and the cable (9) when the latter is tensioned by the user
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A wheelchair (1) comprises a first and a second traction wheel (4) and a traction device (8) having a freewheel (14), a recovery pulley (12) angularly connected to the traction wheels (4) by the freewheel (14), a flexible tension element (9) manually operable via a handle (34) by a user sit on the wheelchair and connected to the recovery pulley (12) to provide a traction torque to the traction wheels ( 4), and a recovery angular spring (M) acting on the recovery pulley (12) for rewinding the flexible tension element (9) along a variable working angle about the recovery pulley (12) when released by a user