Resilient Connecting Element for Office Chair Opening-Angle Control
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Solution Overview
Problem
Existing office chairs with linkage mechanisms for synchronizing the movement of the seat and backrest often result in the backrest moving parallel to the user's back when leaned back, causing discomfort and pushing clothing upwards.
Innovation Solution
A one-piece connecting element, comprising U-shaped seat and backrest leaf springs with a swivel joint, is designed to maintain a predetermined opening angle between the seat and backrest, preventing the backrest from moving parallel to the user's back, and allowing for adjustable spring stiffness and opening angle through leg length changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a linkage mechanism comprising multiple linkages is used to synchronize seat and backrest movement, then the opening angle between seat and backrest can be increased, but the backrest moves parallel to the user's back causing discomfort and pushing clothing upwards
Solution Approach 1:
The patent changes the geometric parameters of the connecting element, specifically the position and orientation of the pivot axes. The effective pivot axis of the backrest leaf spring is positioned at a distance from and parallel to the effective pivot axis of the seat leaf spring, creating a specific geometric relationship that controls the backrest's rotation path. This parameter adjustment ensures the backrest rotates about an axis that does not move parallel to the user's back, eliminating the harmful effect while maintaining opening angle adjustability.
2Reliability
If multiple separate linkages are used to connect seat and backrest, then movement synchronization is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges multiple separate linkage components into a single integrated connecting element. The connecting element is designed as one piece that incorporates both the seat leaf spring and backrest leaf spring with their respective pivot joints. This consolidation maintains the synchronization function while reducing the number of parts, simplifying the structure, and enabling cost-effective manufacturing through processes like injection molding or stamping from spring steel sheet.
Solution Approach 2:
The connecting element performs multiple functions simultaneously: it connects the seat and backrest, provides movement synchronization through its dual leaf spring design, enables opening angle adjustment through pivot axis geometry, and ensures comfortable backrest movement trajectory. This multi-functionality eliminates the need for separate components for each function, reducing overall device complexity.
3Ease of manufacture
If the connecting element is made as one piece, then manufacturing cost is reduced and structure is simplified, but adaptability for adjusting spring stiffness and opening angle is limited
Solution Approach 1:
The patent incorporates adjustability features into the one-piece connecting element. The pivot joints are designed to allow adjustment of the opening angle by changing the relative positions of the pivot axes. Additionally, the leaf springs can be designed with adjustable parameters such as thickness, length, or material properties to modify spring stiffness. This dynamic adjustability is integrated into the monolithic structure, allowing customization without requiring multiple different connecting elements.
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
This design ensures a comfortable and secure seating experience by maintaining the backrest and seat's opening angle, preventing clothing from being pushed up and allowing for customizable stiffness and angle adjustment.
Implementation Method 1
designed to resiliently counteract a pivoting movement of the backrest (3)
Implementation Method 2
The seat leg of the seat leaf spring is connected to the seat surface and the backrest leg of the backrest leaf spring is connected to the backrest. A longitudinal section of the base leg of the seat leaf spring is preferably connected to a longitudinal section of the base leg of the at least one backrest leaf spring on a connecting section, the seat leg being connected to the backrest leg by means of a swivel joint.
Data Source
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AI summary
The invention relates to a piece of seating furniture (1, 2), in particular to an office chair. The piece of seating furniture has a backrest (3) and a seat surface (5). The seat surface is operatively connected to the backrest. According to the invention, the piece of seating furniture has an in particular single-piece connecting element (10, 11, 40, 41). The connecting element is connected to the backrest and the seat surface and designed to counteract a pivoting movement of the backrest in a resilient manner. The connecting element is designed to pivot along the seat surface in a predetermined manner in relation to the pivoting movement of the backrest, and therefore the backrest and the seat surface, during pivoting of the backrest, open one another at an opening angle (29).