Weldable Fuel Tank Vent Mount Using Overmolded HDPE-Acetal Composite
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Solution Overview
Problem
Existing fuel tank venting systems fail to effectively manage air and fuel vapor flow while minimizing hydrocarbon emissions, leading to potential leakage and non-compliance with emission regulations.
Innovation Solution
A vent apparatus with a weldable outer cover made of high-density polyethylene (HDPE) and an interior base of acetal, overmolded to create a sealed venting outlet that couples with a vapor discharge hose, utilizing O-ring seals and frustoconical annular hose mounts to establish multiple seal connections, ensuring minimal hydrocarbon emission and secure attachment to the fuel tank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a vent apparatus is mounted in a fuel tank aperture to manage air and fuel vapor flow, then hydrocarbon emissions are reduced below regulatory limits, but the device complexity increases due to multiple seal connections and overmolded construction
Solution Approach 1:
The outer cover is constructed using composite materials with an HDPE exterior shell overmolded onto an acetal interior base, combining the weldability and chemical resistance of HDPE with the low permeability and structural stability of acetal. This composite construction enables effective vapor management while maintaining manufacturability through overmolding processes.
Solution Approach 2:
The vent apparatus is segmented into distinct functional components: an exterior shell for welding to the fuel tank, an interior base for structural support and vapor conduit integration, and integrated seal elements (O-ring seals and frustoconical annular hose mounts). This segmentation allows each component to be optimized for its specific function while simplifying assembly and manufacturing.
2Reliability
If an outer cover with overmolded construction is used to create a sealed venting outlet, then sealing reliability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The overmolded composite construction of the outer cover integrates multiple materials (HDPE exterior shell and acetal interior base) with complementary properties. The HDPE provides weldability and chemical resistance, while the acetal provides dimensional stability and low permeability. The overmolding process creates inherent sealing interfaces that improve reliability without requiring extremely tight tolerances.
Solution Approach 2:
The frustoconical annular hose mounts act as intermediary elements between the vent apparatus and vapor discharge hoses, providing self-aligning, self-sealing connections. The conical geometry allows for tolerance compensation while maintaining reliable sealing, reducing the precision requirements for both the mount and hose interface.
3Reliability
If multiple seal connections are established using O-ring seals and frustoconical annular hose mounts, then leak-proof attachment is ensured, but the device complexity increases
Solution Approach 1:
The frustoconical annular hose mounts serve as intermediary sealing elements that simplify connections to vapor discharge hoses. The conical geometry provides self-aligning and self-sealing characteristics, accommodating tolerance variations while ensuring leak-proof attachment. This intermediary design reduces the complexity of achieving reliable seals compared to direct rigid connections.
Solution Approach 2:
The O-ring seals and frustoconical annular hose mounts are designed to self-seal through their geometric features and material properties. The conical mounts compress the O-rings automatically upon assembly, creating reliable seals without requiring additional fastening operations or complex adjustment mechanisms. This self-service sealing approach ensures leak-proof attachment while minimizing device complexity.
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
The solution effectively manages fuel tank vapor flow, reduces hydrocarbon emissions below regulatory limits, and ensures a secure, leak-proof attachment to the fuel tank, enhancing compliance with environmental regulations.
Implementation Method 1
The weld pad is that outer and lower portion of the HDPE exterior shell that is mated with the top wall of the fuel tank (while the vent controller is located in the fuel tank aperture) and heated and melted during a welding operation
Implementation Method 2
The weld pad is that outer and lower portion of the HDPE exterior shell that is mated with the top wall of the fuel tank (while the vent controller is located in the fuel tank aperture) and heated and melted during a welding operation
Data Source
AI summary
A vent apparatus is adapted to be mounted in an aperture formed in a fuel tank. The vent apparatus includes a vent controller sized to extend through the fuel tank aperture and an outer cover coupled to the vent controller and welded to the fuel tank to support the vent controller in the fuel tank aperture.