Air Duct Cuff Overmolding for Leak-Resistant Seals
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Solution Overview
Problem
Existing automotive air ducts face issues with weight, bulkiness, and connection reliability, particularly due to the tendency of rubber molded ducts to tear under shear loads and leak at flex points, leading to increased costs and manufacturing complexities.
Innovation Solution
An air duct cuff assembly comprising a tubular body with an internal cuff made of a softer material and an external cuff made of a harder material, both overmolded using injection molding, providing a robust and leak-free seal that resists tearing and can withstand high internal pressures, secured using a mechanical clamp for enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a rubber molded air duct is used, then the duct is flexible and effective, but it is too heavy and bulky for vehicles requiring lighter weight
Solution Approach 1:
The air duct uses a composite construction combining a rigid thermoplastic tubular body with a soft elastomeric cuff material. This composite approach reduces overall weight compared to full rubber construction while maintaining the sealing and flexibility benefits of the soft cuff at the connection port.
Solution Approach 2:
The air duct is divided into two distinct components: a rigid thermoplastic tubular body and a separate elastomeric cuff. This segmentation allows each part to be optimized independently - the rigid body for structural integrity and weight reduction, and the soft cuff for sealing reliability.
2Weight of moving object
If a two-piece construction with thermoplastic tubular body and injection molded rubber seal is used, then the duct is lighter and more compact, but the connection between tubular body and seal breaks after repeated detachment and re-attachment
Solution Approach 1:
The elastomeric cuff is overmolded directly onto the thermoplastic tubular body, creating a unified two-layer structure. This merging eliminates the separate connection interface that would fail under repeated stress, as the cuff and body become integrally bonded through the overmolding process.
Solution Approach 2:
The overmolded composite structure combines the rigid thermoplastic body with the flexible elastomeric cuff in a single integrated component, eliminating weak connection points and improving durability through repeated attachment cycles.
3Ease of operation
If the cuff is made of soft elastomeric polymer material, then the seal is flexible and effective, but the cuff tears under shear-type load due to engine motion or high internal air pressures
Solution Approach 1:
The solution combines soft elastomeric material for flexibility with rigid thermoplastic material for strength. The elastomeric cuff provides sealing flexibility while the rigid thermoplastic tubular body and overmolded structure provide the strength to resist tearing under shear loads and high internal pressures.
Solution Approach 2:
Different regions of the air duct have different material properties optimized for their specific functions: the elastomeric cuff at the connection port provides local flexibility for sealing, while the rigid thermoplastic body provides overall structural strength and tear resistance.
4Manufacturing precision
If overmolding is used to attach the cuff to the hard polymer duct, then a uniform melt bond is created, but the cuff and seal tend to tear under shear-type load because of their soft nature
Solution Approach 1:
The overmolded structure creates a composite material system where the rigid thermoplastic body provides structural strength while the elastomeric cuff provides sealing flexibility. The uniform melt bond from overmolding ensures strong adhesion between the layers, and the rigid thermoplastic reinforcement prevents tearing under shear loads.
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 offers a lightweight, cost-effective air duct configuration that maintains a secure seal under shear loads and high pressures, preventing leaks and tears, while reducing manufacturing complexity and costs.
Implementation Method 1
both overmolded using injection molding
Implementation Method 2
Overmolding is the most robust process for forming the cuff because it creates a uniform melt bond to the hard polymer duct
Data Source
AI summary
A method for manufacturing an air duct includes providing a tubular body having at least one open end which is inserted into an internal cuff mold to form an internal cuff that is secured to and axially extends from the tubular body. The tubular body and the internal cuff are removed from the internal cuff mold and then inserted into an external cuff mold to form an external cuff that is secured to and radially extends from at least the internal cuff. The tubular body with the internal cuff and the external cuff is then removed from the external cuff mold.