Stackable Molded Plastic Rocking Chair with Rocker Stability Design
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Solution Overview
Problem
Existing stackable plastic rocking chairs fail to meet safety standards due to rocker instability and breakage under weight and rocking motion, as they diverge outwardly, leading to potential collapse or structural damage.
Innovation Solution
A stackable rocking chair design featuring spacers between the rockers and front legs, a cross member for additional support, and angled rear legs to enhance stability, allowing for secure stacking and compliance with safety standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the side walls, legs and rockers diverge outwardly from top to bottom to enable stacking, then the chairs can be stacked one on another for easy transport and storage, but the rockers splay outwardly when weight is applied or during rocking motion, causing instability and potential breakage
Solution Approach 1:
The patent applies preliminary anti-action by designing the rockers with a curved base that preemptively counteracts the outward splaying force. The curvature is specifically engineered so that when weight is applied or during rocking motion, the rockers naturally resist outward movement through their geometric shape, preventing instability before it occurs.
Solution Approach 2:
The patent changes the geometric parameter of the rockers from straight to curved with a specific base curvature. This parameter change transforms the rockers' behavior under load, allowing them to maintain stability while preserving the outward divergence needed for stacking. The curved base creates a mechanical advantage that prevents splaying.
2Reliability
If the rockers have a curved base to prevent splaying outward under weight, then rocker stability is improved, but the outward divergence needed for stacking is compromised
Solution Approach 1:
The patent segments the rocker structure into distinct functional zones: the upper portion maintains outward divergence to enable stacking, while the base portion features a curved geometry to prevent splaying. This segmentation allows each part to fulfill its specific function without compromising the other.
Solution Approach 2:
The patent resolves the contradiction by introducing a dimensional solution in the vertical plane. The rockers diverge outward in the horizontal dimension for stacking, while the curved base provides stability in the vertical dimension. This multi-dimensional approach allows both stacking capability and rocker stability to coexist.
3Ease of operation
If continuous rocking is performed on a chair with outwardly diverging legs, then the chair can be used for its intended rocking function, but the increased stress causes legs or rockers to break away
Solution Approach 1:
The patent applies beforehand cushioning by designing the rocker-leg connection with reinforced geometry and appropriate material selection that anticipates the stresses of continuous rocking. The structure is pre-engineered to absorb and distribute rocking forces, preventing breakage before it occurs.
Solution Approach 2:
The patent employs composite materials or composite construction methods to enhance structural integrity while maintaining the rocking function. The combination of materials or structural layers provides both the flexibility needed for rocking and the strength to prevent breakage under repeated stress.
Data Source
AI summary
A stackable rocking chair has a seat, a back, a right front leg and a left front leg attached to the seat, a right rocker and a left rocker, a right rear leg connected to the seat and the right rocker and a left rear leg connected to the seat and the left rocker, a right arm and a left arm that extend from the back and an arm support for each arm. The lower end of each arm support is attached to a rocker and the upper end of each arm support is attached to an arm. Each arm support is adjacent and substantially parallel to one of the front legs, such that there is a gap between the front leg and the arm support. One stackable rocker can be stacked on another stackable rocker by positioning the rockers of one chair within the gaps in the other chair.