Wheelchair Leg Rest Pivot Locking for Adjustable Angles
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Solution Overview
Problem
Existing wheelchair leg rest adjustment solutions require replacing the entire leg rest to change the angle, which is inefficient and lacks flexibility for user-specific needs, as they typically offer fixed angles like 70°, 80°, or 90°, and existing mechanisms are overly complex.
Innovation Solution
A device with a supporting column featuring a pivot joint and circular-arc shaped parts with adjustment holes, allowing for adjustable leg rest angles by aligning and locking bolt holes for predefined positions, enabling easy adjustment between fixed angles without the need for replacing the leg rest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the entire leg rest is replaced to change the angle, then the desired angle can be achieved, but the device complexity and time consumption increase
Solution Approach 1:
The leg rest is divided into a stationary part and a movable part that can be independently adjusted. The movable part includes a support element with adjustment holes that can be positioned at different angles relative to the stationary part, allowing angle adjustment without replacing the entire leg rest assembly.
Solution Approach 2:
The leg rest transitions from a fixed static structure to a dynamic adjustable structure. The support element can be rotated to different positions and locked at desired angles using the adjustment holes and locking mechanism, providing continuous adaptability while maintaining structural integrity.
2Measurement precision
If a toothed rack and locking mechanism are used for angle adjustment, then precise angle positioning is achieved, but the device complexity increases significantly
Solution Approach 1:
The complex toothed rack and side-shifting locking mechanism are removed entirely. Instead, a simplified system using adjustment holes positioned along an arc and a basic bolt-locking mechanism is implemented, achieving sufficient angle positioning precision without the excessive complexity of the toothed rack system.
3Adaptability or versatility
If multiple fixed angle leg rests are provided, then different user needs are met, but the quantity of components and storage space requirements increase
Solution Approach 1:
A single leg rest assembly is designed to perform multiple functions by accommodating different angle configurations. The adjustable support element can be positioned at various angles to serve different user needs, replacing the requirement for multiple separate fixed-angle leg rests.
4Device complexity
If a simple hinge connection is used, then the structure is simple, but angle adjustment and locking capability are lost
Solution Approach 1:
Adjustment holes are pre-positioned at specific angles along an arc on the support element. These holes are prepared in advance at precise locations, allowing the locking mechanism to engage at predetermined stable positions without requiring complex real-time calculation or adjustment during use.
Data Source
Figure 1~4
AI summary
A device (1) for adjusting a wheelchair leg rest, comprising a supporting column (2) to the upper end (3) of which is attached a forward, upper part (4) of a wheelchair and to the lower end (5) of which is attached a footrest (6), wherein at least a lower part (2") of the supporting column (2) is hinge-connected at a link (7), and where to the lower part (2") of the supporting column (2), at a distance from the link (7), there is attached a first, preferably circular-arc-shaped part (8) having a plurality of adjustment holes (9) arranged along a circular arc with origo at the pivotal point of the link (7), and where to a forward, lower part (10) of the wheelchair there is attached a second, preferably circular-arc-shaped part (11) for locking cooperation with the first part (8), a plurality of adjustment holes (9) also being provided on the second part (11) along a similar circular arc as for the first part (8), and where the locking advantageously is effected by a locking bolt (12) passed through two adjustment holes (9) on their respective parts (8, 11) aligned with each other by turning the lower part (2") of the supporting column (2) about the link (7).