Movable Joint Dust Boot Sealing with Interference Fit Lip
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Solution Overview
Problem
Existing dust boot sealing methods for movable joint assemblies are cumbersome, prone to tearing, and require costly machining or crimping processes, which can lead to inadequate seals and increased costs due to material compression set over time.
Innovation Solution
A flexible and elastic dust boot with a radially inwardly extending lip in an interference fit engagement with the housing, combined with a metal insert to resist pull-out and maintain a fluid-tight seal, eliminating the need for external rings and ensuring durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal or plastic rings are placed around the dust boot for biasing, then the seal between housing and dust boot is improved, but the installation becomes cumbersome and the risk of unintentional tearing increases
Solution Approach 1:
The patent removes the external metal or plastic biasing rings from the sealing system. Instead, the dust boot itself is designed with an interference fit configuration that directly engages with the housing, eliminating the need for separate biasing components and their associated installation complexities.
Solution Approach 2:
The sealing and biasing functions are merged into a single integrated structure. The dust boot incorporates both the sealing lip and the biasing engagement features, combining what were previously separate components (seal + external ring) into one unified element that performs both functions simultaneously.
2Reliability
If the outer surface of the housing is machined to provide a surface configuration for sealing, then the seal quality is improved, but the manufacturing cost increases
Solution Approach 1:
The patent applies the interference fit sealing configuration only where needed - at the interface between the dust boot and housing. This localized approach provides effective sealing without requiring extensive machining of the entire housing surface, thereby reducing manufacturing costs while maintaining seal quality.
3Ease of manufacture
If the dust boot is crimped or spun onto the housing to establish a seal, then the installation process is simplified, but the seal may become inadequate over time due to compression set
Solution Approach 1:
The patent employs an interference fit design that allows the dust boot to dynamically adapt to thermal expansion, contraction, and compression set over time. The elastic material maintains continuous contact pressure against the housing surface, ensuring the seal remains effective throughout the service life even as the material properties change.
4Strength
If overspinning or over crimping is performed to compensate for compression set, then the initial seal strength is improved, but the dust boot material is forced to vacate the sealing area causing other problems
Solution Approach 1:
The patent carefully controls the interference fit parameters - the amount of radial interference and the resulting contact pressure - to achieve optimal sealing without excessive force. This balanced design provides sufficient initial seal strength while preventing material displacement and ensuring consistent sealing performance throughout the component's life.
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 provides a strong, durable fluid-tight seal that maintains throughout the life of the movable joint assembly, reducing waste and labor costs while ensuring effective lubricant retention and distribution.
Implementation Method 1
A radially inwardly extending lip which is at least partially spaced axially from the insert and is in an interference fit engagement with the outer surface of the housing for establishing a fluid tight seal
Implementation Method 2
A boot, which is made of a flexible and elastic material, is sealed against the outer surface of the housing and against the ball stud
Implementation Method 3
A metal insert is at least partially embedded within the boot adjacent an end of the boot for resisting pull out of the boot from the housing
Data Source
AI summary
The movable joint assembly includes a housing which extends along an axis and has an outer surface and an open interior. A ball stud is partially disposed in the open interior and projects out of the housing. A flexible and elastic boot is sealed against the outer surface of the housing and against the ball stud. A metal insert is at least partially embedded within the boot adjacent an end of the boot for resisting pull out of the boot from the housing. The boot includes a lip which is at least partially spaced axially from the insert and extends radially inwardly and is in an interference fit engagement with the outer surface of the housing for establishing a fluid tight seal of the housing and for maintaining the fluid tight seal in response to injection of a lubricant into the open interior of the housing.