Mobility Device Symmetrical Force Transfer
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Solution Overview
Problem
Conventional mobility devices, such as wheelchairs, face challenges in reducing torsional stiffness, size, weight, and complexity due to the need for high force transfer from a central actuating device to the backrest, which is exacerbated by the presence of a bulky battery pack and requirements for low seat height and adequate ground clearance.
Innovation Solution
A mobility device design featuring a main frame with a central longitudinal axis in the median plane, utilizing a rotation transfer member that extends transversely through a T-shaped body support member, allowing symmetrical force transfer from a medial location to bilateral locations, thereby reducing torsional stiffness and simplifying the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If force is transmitted from one side to control the backrest, then the backrest can be actuated, but the torsional stiffness requirement increases and the physical dimension and weight are adversely affected
Solution Approach 1:
The patent applies asymmetry by positioning the actuating device centrally on the chassis rather than laterally on one side. This central positioning creates a symmetrical force distribution to both backrest sides, eliminating the need for high torsional stiffness and reducing the overall structural weight requirement.
Solution Approach 2:
The patent uses a tilt/lift system arranged centrally to pre-position the backrest and seating system, enabling the actuating device to work from a central location. This preliminary positioning action allows force transmission without requiring excessive torsional stiffness in the backrest structure.
2Ease of operation
If force is transmitted from one side to control the backrest, then the backrest can be actuated, but the device complexity increases
Solution Approach 1:
By positioning the actuating device centrally rather than laterally, the patent simplifies the force transmission path. The symmetrical arrangement eliminates complex lateral force transfer mechanisms and reduces the overall device complexity.
3Use of energy by moving object
If the chassis contains a large battery pack centrally arranged, then power is available, but the chassis becomes bulky
Solution Approach 1:
The central chassis structure serves multiple functions: it houses the battery pack, provides structural support, and acts as the mounting location for the actuating device. This multi-functionality reduces the need for additional structural components, thereby reducing overall chassis volume despite the large battery pack.
4Adaptability or versatility
If ground clearance requirements are met, then the device can navigate terrain, but the seat height increases
Solution Approach 1:
The patent employs a dynamic tilt/lift system that can adjust the seating system angle and position. This dynamic adjustment allows the device to maintain adequate ground clearance for terrain navigation while keeping the seat height low for user accessibility, as the system can tilt the entire seating assembly rather than requiring fixed high clearance.
Data Source
Figure 1~2
Figure 3a~4
Figure 5~6c
AI summary
A mobility device (l) comprising: a main frame (3) having a central longitudinal axis which coincides with the median plane of the mobility device (1), an elongated body support member (13b) which has a central longitudinal axis (At) that is contained in a median plane of the mobility device (1), the body support member (13b) being pivotally connected to the main frame (3) via a medial pivot connection (17), and an elongated rotation transfer member (13c) rotatably connected to the body support member (13b), wherein the rotation transfer member (13b) has a central longitudinal axis (A2) which extends transversally relative to the central longitudinal axis (At) of the body support member (13b).