Wheelchair Backrest Shock Absorber With Lockable Recline Control
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Solution Overview
Problem
Conventional wheelchairs lack a mechanism to safely allow users to recline the backrest for stretching while ensuring safety during movement, as they may inadvertently recline, posing a risk of falling.
Innovation Solution
A shock absorber system for wheelchairs comprising a base tube, resilient member, supporting member, and outer sleeve, where the outer sleeve is rotatable between a limited and retractable position, allowing the backrest to pivot rearwardly when in the retractable position and preventing recline when in the limited position, using a compression spring and sliding slots to control movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the backrest portion is made pivotally connected to allow reclining for stretching, then user comfort and stretching capability are improved, but the risk of accidental recline during movement increases, compromising safety
Solution Approach 1:
The shock absorber system dynamically transitions between two states: a locked state during wheelchair movement that prevents backrest recline, and an unlocked state during stationary use that allows backrest reclining for stretching. This dynamic switching resolves the contradiction by adapting the system's rigidity based on operational context.
Solution Approach 2:
The outer sleeve acts as an intermediary component that controls the engagement between the supporting member and the resilient member. Through rotational movement, the outer sleeve mediates between the locked and unlocked states, enabling safe transition between movement and stretching modes.
2Reliability
If a locking mechanism is added to prevent accidental recline during movement, then safety is improved, but the device complexity increases
Solution Approach 1:
The locking mechanism is merged with the shock absorber's existing structure. The outer sleeve integrates the locking function by utilizing its rotational movement to engage or disengage the limiting protrusion with the limiting slot, combining the safety lock with the backrest adjustment mechanism rather than adding a separate independent locking system.
Solution Approach 2:
The system employs self-service locking through the outer sleeve's rotational movement. When the outer sleeve rotates to the limited position, the limiting protrusion automatically engages with the limiting slot to lock the backrest, without requiring external actuators or complex control systems. The resilient member also provides automatic reset functionality.
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
Enables users to safely recline the backrest for stretching while maintaining safety during wheelchair movement by allowing controlled pivoting of the backrest and preventing accidental recline during transit.
Implementation Method 1
a resilient member (2), disposed in the accommodating space, a supporting member (3)... such that the supporting member is movable relative to the base tube along the axis against a resilient force of the resilient member when the backrest portion pivots relative to the seat portion to incline rearwardly
Data Source
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AI summary
A shock absorber is mounted on a wheelchair (90), and includes a base tube (1) connected to a seat (91) of the wheelchair (90) and formed with an elongated slot (13), a resilient member (2) disposed in the base tube (1), a supporting member (3) for interconnecting a backrest (92) of the wheelchair (90) and the resilient member (2), and an outer sleeve (5) sleeved on the base tube (1) and the supporting member (3). The supporting member (3) is formed with a slot unit including a sliding slot (32), and a limiting slot (33) extending transversely from a bottom end of the sliding slot (32) and parallel to the elongated slot (13). The outer sleeve (5) includes a limiting protrusion (531) extending through the elongated slot (13) into the slot unit, and rotatable relative to the base tube (1) and the supporting member (3) from a limited position to a retractable position where the supporting member (3) is immovable and movable relative to the base tube (1), respectively.