Leisure Chair Linkage for Stable Reclining and Legrest Extension
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Solution Overview
Problem
Leisure chairs with telescopic legrests tend to tip over when shifted from a sitting to a lying position due to a rearward shift in center of gravity, and separate control mechanisms for backrest inclination and legrest extension increase costs and operational complexity.
Innovation Solution
A leisure chair design featuring a single control rod to adjust both backrest inclination and legrest extension, utilizing pivotal rod units, link units, and a driving mechanism with springs and rods to maintain stability and reduce component costs, with a base structure that counterbalances the center of gravity when lying down.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the backrest rearward inclination angle is increased and the legrest is extended to provide a comfortable lying position, then the user comfort is improved, but the chair becomes apt to tip over due to rearward shift of center of gravity
Solution Approach 1:
The patent employs a counterbalancing mechanism where the base structure and its positioning are designed to counteract the rearward shift of center of gravity when the user lies down. The base is positioned and dimensioned to provide a counterbalancing moment that prevents the chair from tipping over, directly resolving the stability issue while maintaining the comfortable lying position.
2Manufacturing precision
If two separate control rods or buttons are used to control backrest inclination and legrest extension, then the adjustment precision is improved, but the device complexity and component costs increase
Solution Approach 1:
The patent combines the control functions for backrest inclination adjustment and legrest extension into a single control rod. This control rod is linked through a mechanical transmission system that simultaneously actuates both adjustment mechanisms, thereby reducing component count and operational complexity while maintaining precise adjustment capability through the interconnected mechanical linkages.
Solution Approach 2:
The single control rod serves multiple functions: it controls both the backrest inclination angle and the legrest extension. This multi-functional control mechanism allows one component to perform what previously required two separate controls, simplifying the user interface and reducing overall system complexity while preserving adjustment precision through its mechanical design.
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
Enhances stability and convenience by allowing synchronized adjustment of the backrest and legrest, reducing the risk of tipping and simplifying operation while maintaining cost-effectiveness.
Implementation Method 1
Each of the two pivotal rod units is pivotably connected to and movable relative to one of the lower coupling plates
Implementation Method 2
an adjusting unit including a driving rod pivotably connected to a rear end of the legrest unit
Data Source
AI summary
A leisure chair includes a backrest pivotably connected to a seat. A connection seat is mounted between a base and the seat and includes a lower coupling portion mounted to the base, an upper coupling portion mounted to the seat, and two pivotal rod units pivotably connected to two sides of the lower coupling portion, respectively. The upper coupling portion is pivotably connected to the pivotal rod units. When a control rod moves rearwards, a push portion on the control rod actuates a pull rod to control a pneumatic rod for adjusting a rearward inclination angle of the backrest. When the control rod moves forwards, a pressing portion of the control rod presses against two swaying rods to extend the legrest unit, and the center of gravity of the upper coupling portion can be located in front of the center of gravity of the base to provide enhanced lying stability.