Stand-up Wheelchair Seat Backrest Angle Coordination
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Solution Overview
Problem
Existing stand-up wheelchairs face issues with user comfort and stability, particularly when transitioning between sitting and standing positions, as the angle between the seat and backrest does not adjust adequately, leading to physical discomfort and increased risk of decubitus due to inadequate adaptation to the user's anatomical needs.
Innovation Solution
The wheelchair's design allows for adjustable vertical distance between front pivot points to change the angle of inclination of the seat, with a telescopic frame and sliding guide mechanism that adjusts the angle between the seat and backrest, ensuring the user's upper body remains vertical and reducing shearing movements, and includes a mechanism to adjust the backrest's angle and position relative to the seat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the angle between the seat and backrest is reduced when the seat tilts, then the user can take a more comfortable sitting position, but the user is constrained and suffers physical discomfort such as shortness of breath and nausea
Solution Approach 1:
The patent applies dynamics by making the angle between the seat and backrest adjustable rather than fixed. The articulated parallelogram mechanism allows the angle to dynamically change based on the seat's inclination state, enabling the system to adapt to different user needs and positions automatically.
Solution Approach 2:
The patent changes the geometric parameter (angle between seat and backrest) based on the seat's inclination angle. When the seat tilts, the angle between seat and backrest is automatically adjusted to a larger value, preventing the user from being squeezed and eliminating physical discomfort while maintaining comfort.
2Object-affected harmful factors
If the backrest cushion is displaced vertically in accordance with the angular inclination of the seat, then the shearing movement between the user's body and the backrest is avoided, but the angle between the seat and backrest is reduced causing user constraint
Solution Approach 1:
The system dynamically adjusts both the vertical position of the backrest cushion and the angle between seat and backrest based on the seat's inclination. This dynamic coordination ensures that the backrest remains properly positioned relative to the user's body while maintaining sufficient angular space to prevent constriction.
Solution Approach 2:
The patent changes multiple parameters simultaneously: the vertical displacement of the backrest cushion and the angle between seat and backrest. Both parameters are adjusted in coordination with the seat's inclination angle to achieve the optimal balance between preventing shearing movement and maintaining user freedom.
3Device complexity
If the vertical distance between front pivot points is fixed, then the structure is simple, but the angle between the seat and backrest cannot be adjusted adequately when the seat tilts
Solution Approach 1:
The patent introduces dynamic adjustability to the vertical distance between front pivot points through the telescopic chassis section. This allows the distance to change automatically with the seat's inclination, enabling adequate angle adjustment between seat and backrest while maintaining relative structural simplicity.
Solution Approach 2:
The patent changes the physical parameter (vertical distance between pivot points) to enable adequate angle adjustment. By making this distance variable through the telescopic mechanism, the system achieves the versatility needed to adjust the seat-backrest angle while keeping the overall structure relatively simple.
Data Source
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AI summary
A stand-up wheelchair, comprising an undercarriage (40) and a stand-up frame (41) that is fastened to the front part of the undercarriage (40), a seat (10) that is pivotally fastened to the front part (5, 20) of the undercarriage (40) being connected to said stand-up frame, the seat being displaceable from a sitting position into a standing position by way of an actuator (6), further comprising a backrest (24) that is connected to the seat (10) in an articulated manner, disposed at an angle (a) thereto and has a back cushion (17), and comprising at least one articulated parallelogram (45) pivotally arranged beneath the seat (10) on the front part (5, 20) of the undercarriage (40), characterized in that the angle of inclination (?) of the seat (10) can be varied, and during a change of the angle of inclination (?) of the seat (10) out of the horizontal line (H) the angle (ai) between the backrest (24) and the seat (10) is changed at an angle (a2).