Co-molded Strain Relief for Liquid-Tight Cable Sealing
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Solution Overview
Problem
Existing liquid-tight strain reliefs for cables, wires, and tubing do not effectively provide both liquid-tight sealing and strain relief protection, especially when cables or rods are inserted through orifices in work pieces, as they often fail to maintain a secure grip and seal.
Innovation Solution
A co-molded strain relief system comprising a tubular bushing with resilient outer and inner fingers, and a dome-shaped gland with a membrane, which provides a unitary construction for secure engagement with work pieces and cables, ensuring liquid-tight sealing and strain relief through frictional engagement and flexible finger action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional strain relief is used, then cable protection is provided, but liquid-tight sealing is not effectively achieved
Solution Approach 1:
The patent combines the sealing function and strain relief function into a single integrated component. The bushing structure includes both sealing elements (lip seal, gasket) and strain relief elements (resilient fingers, gripping surfaces) merged into one unitary construction, eliminating the need for separate sealing components and strain relief components while achieving both functions simultaneously.
Solution Approach 2:
The bushing is designed as a multi-functional component that performs multiple roles: it provides liquid-tight sealing through integrated seals, strain relief through resilient gripping fingers, cable guidance through the aperture, and structural support through the flange. This universal design replaces multiple specialized components with one versatile element.
2Adaptability or versatility
If multiple components are assembled, then functionality is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent merges multiple previously separate components (bushing, seal, strain relief elements, flange) into a single co-molded unitary construction. This eliminates assembly steps, reduces part count, and simplifies manufacturing while maintaining all necessary functionalities of strain relief, sealing, and cable guidance.
Solution Approach 2:
The bushing is constructed using composite materials with different properties in different regions - resilient elastomeric material for the gripping fingers, softer seal material for liquid-tight sealing, and harder structural material for the flange and aperture. These composite materials are co-molded into a single integrated component, achieving multi-functionality without complex assembly.
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 co-molded strain relief system effectively secures cables and rods within work pieces, providing both liquid-tight sealing and strain relief by engaging the work piece and cable with resilient fingers, ensuring durability and reliability in maintaining the seal and protecting against strain.
Implementation Method 1
the resilient inner fingers of the bushing flex outwardly to enable the cable to pass through, while engaging and digging into the cable to clasp it and provide strain relief
Implementation Method 2
The outer fingers frictionally engage the work piece
Implementation Method 3
A cable is inserted within the strain relief by piercing the membrane, which stretches and provides a seal against the cable
Data Source
AI summary
A liquid-tight strain relief includes a tubular-shaped bushing and a dome-shaped gland. The bushing includes a flange with arcuate slots, a centrally-located aperture, a plurality of resilient outer fingers, and a shoe slideably received within a lateral groove of the bushing. The gland includes a head having a centrally-located membrane. The head is co-molded with and encapsulates the flange, resulting in a strain relief having a unitary construction. The strain relief is adapted to be inserted within an orifice of a work piece, and the outer fingers frictionally engage the work piece. A cable is inserted within the strain relief by puncturing the membrane, which then stretches and provides a seal against the cable. The cable is gripped to the strain relief when the shoe is pressed against the cable. The shoe is held against the cable by teeth on the shoe, which engage opposing locking ribs on the bushing.