Composite Lattice CNG Vessel for Weight Reduction
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Solution Overview
Problem
Conventional CNG storage vessels are heavy and unwieldy due to their steel construction, making them unsuitable for unobtrusive placement in vehicles, and previous solutions, such as internal I-beams or multi-layer sheet metal designs, either add weight or compromise safety.
Innovation Solution
A lightweight storage vessel design featuring a lattice frame of fiber-reinforced composite material with internal supports that counteract high internal pressures, integrated with a fluid-impermeable outer shell and a valve module, allowing for desired geometries and safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional steel construction is used for CNG storage vessels, then strength and pressure resistance are improved, but weight increases making the vessel heavy and unwieldy
Solution Approach 1:
The patent employs fiber-reinforced composite materials (such as carbon fiber, glass fiber, or aramid fiber reinforced polymers) to construct the storage vessel walls and internal supports. These composite materials provide high strength-to-weight ratio, enabling the vessel to withstand high CNG pressures (typically 200-300 bar) while significantly reducing overall weight compared to conventional steel construction. The composite structure maintains structural integrity through the reinforcement fibers distributed throughout the polymer matrix.
Solution Approach 2:
The vessel is divided into multiple structural components including a cylindrical or spherical pressure hull, internal support rings, longitudinal stiffeners, and end closures. This segmentation allows each component to be optimized for its specific function while collectively providing the required pressure resistance. The modular structure also facilitates easier manufacturing, assembly, and maintenance compared to monolithic steel vessels.
2Shape
If internal I-beams are added to form different shapes, then shape conformability is improved, but weight increases and welding creates failure points compromising safety
Solution Approach 1:
Internal support structures are constructed using composite materials matching the pressure hull, eliminating the need for heavy metal I-beams. The composite supports can be molded into complex geometries directly during manufacturing, providing structural reinforcement while maintaining low weight. This approach avoids the weight penalty and safety concerns associated with welding metal supports to the pressure hull.
Solution Approach 2:
The internal support structures are integrated with the pressure hull as a unified composite structure rather than separate components requiring assembly. The supports and hull are manufactured together as a single piece or pre-bonded using adhesive joints, eliminating welding operations and reducing the number of potential failure points. This merging of structures maintains geometric flexibility while improving safety.
3Strength
If multi-layer sheet metal with diffusion bonds is used, then structural reinforcement is improved, but weight increases due to heavy sheet metal and diffusion bonds
Solution Approach 1:
The patent replaces heavy multi-layer sheet metal construction with fiber-reinforced composite materials that provide equivalent or superior structural reinforcement at a fraction of the weight. The composite layers are bonded using lightweight adhesive joints rather than diffusion bonding of metal sheets. This substitution maintains the multi-layer reinforcement concept while dramatically reducing the overall vessel weight through the inherent lightness of polymer matrix composites compared to metal sheets.
4Strength
If conventional cylindrical or spherical vessels are used, then pressure resistance is improved, but volume and weight increase making them unsuitable for unobtrusive placement in vehicles
Solution Approach 1:
The use of high-strength fiber-reinforced composite materials allows the vessel to maintain pressure resistance capabilities while adopting compact, space-efficient geometries. The composite structure's high specific strength enables the design of smaller-diameter vessels that can fit within vehicle constraints. Common configurations include compact cylindrical tanks with optimized length-to-diameter ratios, or even complex multi-chamber arrangements that maximize storage density while minimizing overall volume for unobtrusive vehicle integration.
Data Source
AI summary
A vessel for storing pressurized gas. The storage vessel may be manufactured in a variety of predetermined shapes. Plural frame members are interconnected with each other, collectively forming a lattice frame. A network of internal supports is disposed within the interior of the lattice frame, the internal supports being made of a carbon-reinforced composite material. The storage vessel has an outer shell made up of layers of carbon-reinforced composite material sheets enveloping the exterior of the lattice frame.