Wheelchair Seat Pivot Layout for Low-Force Height and Tilt Adjustment
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Solution Overview
Problem
Existing wheelchairs with adjustable seat height and inclination are structurally complex, heavy, and costly, which impairs handling properties and increases the risk of decubitus due to high operating forces required for adjustment.
Innovation Solution
A wheelchair design featuring telescopic tubes for height adjustment and a locking plate mechanism with an arc-shaped detent for inclination adjustment, where the axis of rotation is above the seat frame, allowing the seat system's pivot axis to align with the overall center of gravity, reducing the need for high operating forces and simplifying the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a telescopic cylinder is used to facilitate seat system adjustability, then the adjustability of the seat system is improved, but the wheelchair becomes more expensive, heavier, and more complex
Solution Approach 1:
The patent extracts the complex telescopic cylinder mechanism from the wheelchair design and replaces it with a simpler manual adjustment system consisting of a seat frame mounted on the base frame with direct pivot connection. This removes the unnecessary complexity while retaining the essential adjustability function through manual operation.
Solution Approach 2:
The patent employs simple, inexpensive components such as a basic pivot connection and manual locking mechanism instead of expensive telescopic cylinders. The design prioritizes cost-effective solutions that achieve the required functionality without over-engineering the adjustment system.
2Adaptability or versatility
If a telescopic cylinder is used to facilitate seat system adjustability, then the adjustability of the seat system is improved, but the wheelchair weight increases and handling properties are impaired
Solution Approach 1:
The heavy telescopic cylinder is removed from the design and replaced with a lightweight manual adjustment mechanism. The seat frame is directly mounted on the base frame with a simple pivot connection, eliminating the weight penalty associated with powered or semi-powered adjustment systems.
3Ease of operation
If the axis of rotation is shifted to the common center of gravity to reduce actuating forces, then the operating forces are reduced, but the wheelchair becomes structurally very complex
Solution Approach 1:
The patent positions the pivot axis of the seat frame at or near the center of gravity of the combined seat system and user. This creates an equipotential condition where the moment arm for the user's weight is minimized, naturally reducing the actuating forces required for inclination adjustment without requiring complex mechanical advantage systems.
4Object-affected harmful factors
If the seat frame is made height-adjustable and inclination-adjustable, then the risk of decubitus is reduced, but the structure becomes more complex and heavier
Solution Approach 1:
The patent implements dynamic adjustability of the seat frame, allowing both height and inclination to be modified according to the user's needs. The seat frame can be adjusted to different positions and angles to optimize pressure distribution and prevent decubitus, while maintaining a relatively simple overall structure through the use of direct mounting and manual adjustment mechanisms.
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 design results in a lightweight, structurally simple wheelchair with easy manual adjustment of the seating system, reducing the risk of decubitus by distributing body weight effectively and minimizing the forces required for inclination changes.
Implementation Method 1
the seat frame being connected to the underframe via at least two telescopic tubes each consisting of a lower and an upper tube
Implementation Method 2
a seat frame which is attached to the underframe in a height-adjustable manner, which is pivotably mounted about an axis of rotation and whose inclination relative to the horizontal and its height can be adjusted
Implementation Method 3
a locking plate is attached to the longitudinal tubes to adjust the inclination of the seat frame
Data Source
AI summary
The invention relates to a wheelchair which comprises: a underframe (1) to which front steerable wheels (6) and rear drive wheels (7) are fixed at a distance from one another; a seating frame (3) which is height-adjustably fixed to said underframe (1), mounted so as to be able to pivot about a rotational axis (D), and which can be incline-adjusted with regard to the horizontal line (H) as well as height-adjusted; and a backrest frame which is connected to the seating frame (3) consisting of two longitudinal tubes (9) lying opposite each other and at least one transverse tube (10) which interconnects these longitudinal tubes (9); a) said seating frame (3) being connected to the underframe (1) by means of at least two telescopic tubes (2) each formed from one lower (2b) and one upper (2a) tube; b) the lower ends of these lower tubes (2b) being rigidly fixed to said underframe (1), and the invention being characterised in that: c) the upper ends of the upper tubes (2a) are connected to the seating frame (3) in the rotational axis (D); d) a detent plate (14) is arranged on each of the longitudinal tubes (9) and connected to the upper tubes (2a), for the purpose of adjusting the incline of the seating frame (3); and e) the rotational axis (D) is provided above said seating frame (3).