Foldable Chair Frame Geometry for Comfortable Backrest Angle
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Solution Overview
Problem
Conventional foldable chair frames often have backrests that are inclined at angles outside the comfort range, failing to provide adequate support and comfort to users.
Innovation Solution
The design includes a foldable chair frame with integrally formed front legs and backrest rods at an obtuse angle, along with pivotal connections that allow the front leg to be inclined backward and the rear leg to be inclined forward, resulting in a backrest rod inclination angle within a comfortable range, enhancing ergonomic seating and ease of folding/unfolding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the backrest rod is inclined at the same angle as the front leg, then the chair structure is simplified, but the backrest angle falls outside the comfort range and cannot provide adequate support
Solution Approach 1:
The backrest assembly is segmented into multiple components: the backrest rod (3), front leg (11), rear leg (12), and seat rod (2). Each segment has its own inclination angle and pivotal connection points, allowing independent optimization of structural simplicity and ergonomic comfort. The backrest rod is divided into a first section (31) and second section (32) with different orientations.
Solution Approach 2:
The chair frame employs dynamic pivotal connections at key joints (first pivotal point P1 on front leg, second pivotal point P2 on rear leg) that allow the backrest rod to achieve its optimal inclination angle when the chair is unfolded, while maintaining structural simplicity during folded and unfolded states.
2Reliability
If the backrest rod is inclined backward at a large angle, then the backrest provides strong support, but the chair becomes difficult to fold and unfold
Solution Approach 1:
The pivotal connections at P1 and P2 enable the backrest rod to dynamically adjust its position. During folding, the rod pivots at these points to reduce the overall chair dimension, while during use, it maintains the optimal backward inclination for support. This dynamic capability resolves the conflict between support strength and folding ease.
Solution Approach 2:
The inclination angle of the backrest rod is optimized to be less than that of the front leg, creating a specific geometric relationship that allows the chair to achieve both adequate backrest support and compact folded dimensions. The angle parameters are carefully selected to balance support reliability and folding operability.
3Ease of operation
If the front leg is inclined backward and rear leg is inclined forward, then ergonomic seating is improved, but the chair frame complexity increases
Solution Approach 1:
The backrest rod is integrally formed with the front leg, merging two components into one. This integral structure simplifies the overall frame while still allowing the necessary pivotal connections at P1 and P2 to achieve the ergonomic angles for both front and rear legs.
Solution Approach 2:
The front leg structure serves multiple functions: it provides the forward inclination for ergonomic seating, supports the integrally formed backrest rod, and acts as one of the load-bearing legs of the chair. This multi-functionality reduces the need for additional structural 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 configuration provides improved comfort and support by adjusting the backrest angle to be less than the front leg's inclination, promoting ergonomic seating while simplifying the folding and unfolding process, making the chair more compact and stable.
Implementation Method 1
pivotal connections that allow the front leg to be inclined backward and the rear leg to be inclined forward
Implementation Method 2
The upper end of the rear leg is configured to abut and support the front leg when the foldable chair frame is unfolded
Data Source
AI summary
Disclosed are foldable chair frames and foldable chairs. A foldable chair frame includes left and right side frames, each having a front leg, a backrest rod, a rear leg, and a seat rod. The backrest rod is integrally formed with the front leg and extended from the upper end of the front leg at an obtuse angle with respect to the front leg. The rear leg has an upper end configured to abut and support the front leg when the foldable chair frame is unfolded. The seat rod is pivotally connected to the front and rear legs. A foldable chair frame also includes front and rear supporting rods disposed between the left and right side frames at front and rear sides of the foldable chair frame. The front and rear supporting rods are pivotally connected to the left and right side frames.