Decoupled Frame for Rotomolded Spa Shell
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Solution Overview
Problem
Rotomolded spas face challenges in incorporating structural support while maintaining efficiency and minimizing material usage, leading to potential deformation under weight and thermal stress, which affects sealing, energy efficiency, and material longevity.
Innovation Solution
A decoupled frame system comprising individual components assembled within the spa shell via openings in the peripheral wall, providing superior structural support and minimizing deformation while accommodating thermal expansion, with a panel assembly mechanism for enhanced sealing and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the rotomolded shell is over-designed with increased structural thickness to withstand water weight and bather weight, then the structural strength is improved, but the amount of plastic material used increases significantly, affecting costs
Solution Approach 1:
The spa structure is divided into two functional segments: a rotomolded shell providing waterproof containment and a separate modular frame structure providing structural support. The frame consists of multiple independent components (corner posts, side rails, cross members) that can be separately manufactured and assembled, allowing structural strength to be achieved without increasing plastic material usage in the shell.
Solution Approach 2:
The invention employs a composite structure combining rotomolded plastic shell with a frame made of different materials (metal or rigid plastic). This composite approach allows each material to perform its optimal function - the plastic shell for waterproofing and chemical resistance, and the frame for structural support and rigidity - without requiring the plastic shell to be over-engineered.
2Strength
If the rotomolded shell is over-designed with increased structural thickness to support spa cover weight in cold climates, then the structural strength is improved, but the manufacturing cost increases due to excessive material usage
Solution Approach 1:
The support function for spa cover weight is segregated from the rotomolded shell to a dedicated frame structure. The frame's corner posts and cross members are specifically designed to bear the cover weight, allowing the shell to be manufactured with standard thickness without reinforcement, thus maintaining manufacturing efficiency.
Solution Approach 2:
The frame structure acts as an intermediary between the rotomolded shell and the spa cover. Instead of the shell directly supporting the cover weight, the frame serves as a mediating structure that distributes and bears the load, protecting the shell from excessive stress while maintaining manufacturing simplicity.
3Stability of the object's composition
If the rotomolded shell is designed with increased structural thickness to prevent deformation under load, then the structural stability is improved, but the total amount of plastic material used increases, affecting costs
Solution Approach 1:
The structural stability function is segmented from the rotomolded shell to a separate frame structure. The frame provides the rigid skeleton that prevents deformation under load, while the shell maintains its standard thickness for cost-effectiveness. The frame's modular components (corner posts, side rails, cross members) work together to distribute loads and maintain structural integrity.
4Reliability
If the rotomolded shell is over-designed to prevent warping and maintain straight profile, then the sealing performance is improved, but the amount of plastic material used increases significantly
Solution Approach 1:
The function of preventing warping and maintaining straight profile is assigned to the frame structure rather than the rotomolded shell. The frame's rigid members provide the structural backbone that keeps the spa upright and prevents shell distortion, ensuring proper sealing with the cover without requiring excessive plastic material in the shell.
Data Source
AI summary
A spa having a rotomolded unibody shell defining a basin, an upper edge surrounding the basin, a peripheral wall, a cavity between the basin and the peripheral wall. The peripheral wall having at least one opening leading to the cavity. The spa including a frame, decoupled from the spa shell, in the form of a plurality of individual components introducible into the cavity within the shell via the opening in the shell, and assemblable to one another inside the shell. The frame including side beams and couplers in continuous abutment with the upper edge of the shell, offering a superior structure and support.