Adjustable Chair Backrest Ratchet Lock for Safe Reclining
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Solution Overview
Problem
Conventional chairs with adjustable backrests lack a reliable mechanism for safe and controlled reclining adjustment, which can lead to unintentional movements and instability, particularly in highchairs where safety is a concern.
Innovation Solution
A chair design featuring a pivotally connected backrest with a positioning unit, an operating unit, and a safety mechanism that includes ratchet-teeth positioning blocks and a limiting mechanism to control the reclining angle, preventing sudden movements and ensuring stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional control component with springs and pins is used to adjust the backrest, then the backrest can be adjusted to different inclinations, but the mechanism lacks reliability and can lead to unintentional movements and instability
Solution Approach 1:
The patent employs a dynamic ratchet mechanism where the positioning member can move freely in one direction (allowing backrest reclining) but is locked in discrete positions by engagement with stop portions. This dynamic design provides both ease of adjustment and stability, resolving the contradiction between operational ease and reliability.
Solution Approach 2:
The positioning member acts as an intermediary between the operating unit and the backrest. It translates the operating unit's movement into controlled positioning actions, mediating the adjustment process to ensure both ease of operation and reliable positioning through its engagement with the stop portions.
2Adaptability or versatility
If the backrest is allowed to recline freely to a horizontal position, then maximum adjustment range is achieved, but safety is compromised due to potential accidental movement
Solution Approach 1:
The safety mechanism preemptively prevents the backrest from reaching the horizontal position by using stop portions that physically block further reclining. This preliminary anti-action eliminates the safety hazard before it can occur, while still allowing a substantial useful reclining range for normal operation.
Solution Approach 2:
The patent converts the potential harmful factor (uncontrolled reclining to horizontal position) into a beneficial safety feature. The stop portions, which could be seen as limiting the adjustment range, actually provide the benefit of preventing accidental movement to dangerous positions, thus converting a limitation into a safety advantage.
3Reliability
If a positioning mechanism with multiple stop portions is implemented, then controlled positioning is achieved, but the device complexity increases
Solution Approach 1:
The positioning mechanism is segmented into discrete, simple elements: multiple stop portions at different heights and a positioning member with engagement features. This segmentation allows for reliable multi-position control while keeping each individual component simple and easy to manufacture, thus managing overall device complexity.
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 allows for controlled adjustment of the backrest to multiple positions while preventing unintentional reclining to a horizontal position, enhancing safety by limiting the reclining distance and preventing overturning, thus ensuring secure seating for users.
Implementation Method 1
A spring 37 connects a corresponding coupling seat 28 to the corresponding box structure 17 in order to provide a restoring force
Data Source
AI summary
A chair includes a positioning unit that is provided in a receiving portion of an armrest and that includes shorter and taller stop portions. A positioning member is retained movably on a rear side of a backrest, and has one end extending into the receiving portion to abut against a selected one of the stop portions. An operating unit is connected to and is operable to move the positioning member for selectively disengaging and engaging the stop portions. A safety mechanism is provided on the backrest and the operating unit, and is operable in either a limiting state, where the positioning member is unable to move past the taller stop portion, or a non-limiting state, where the positioning member is able to move past the taller stop portion.