Cable Gland with Segmented Strain Relief and Sealing
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Solution Overview
Problem
Existing cable glands face challenges such as complex designs, limited sealing effectiveness, suitability only for specific cable diameters, high manufacturing and assembly costs, and difficulty in achieving both effective strain relief and sealing, especially in industrial applications.
Innovation Solution
A cable gland design that spatially separates strain relief and sealing functions, using a one-piece clamping cage with film hinges and spherical pressure elements for strain relief, and a cylindrical sealing insert for sealing, both pressed onto the cable sheath by a pressure screw, allowing for adaptability to different cable diameters and independent selection of materials for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sealing element is used to provide both sealing and strain relief functions, then the device complexity is reduced, but the sealing effectiveness and strain relief performance deteriorate
Solution Approach 1:
The cable gland is divided into separate functional components: a sealing element (gland) and a clamping element (clamping cage with balls). The sealing element provides sealing through its elastic material deforming onto the cable, while the clamping element provides strain relief through balls pressed against the cable by a clamping screw. This segmentation allows each component to optimize its specific function without compromise.
Solution Approach 2:
The strain relief function is extracted from the sealing element and assigned to a separate clamping element. The sealing element is taken out from the combined sealing-strain relief structure and designed independently to focus solely on sealing, while the clamping element handles strain relief through its ball-and-screw mechanism.
2Manufacturing precision
If a cable gland is designed for a specific cable diameter, then the manufacturing precision is improved, but the adaptability to different cable diameters deteriorates
Solution Approach 1:
The clamping element uses spherical balls that can be selected in different diameters to match different cable diameters. The clamping screw mechanism allows adjustment of the clamping force and position. By changing the ball diameter parameter and the clamping force, the same basic structure can accommodate a range of cable diameters while maintaining precise sealing and strain relief performance.
3Strength
If balls are used for clamping the cable, then the strain relief is improved, but the risk of ball loss during assembly increases
Solution Approach 1:
Instead of trying to prevent ball loss through complex retention mechanisms, the design inverts the approach by making the balls an integral part of a modular clamping element assembly. The balls are contained within the clamping cage structure during assembly, and the assembly process is designed to guide components into place, reducing the risk of ball loss while maintaining effective strain relief through the ball-cable contact.
4Reliability
If the sealing element is made from soft material for effective sealing, then the sealing effectiveness is improved, but the strain relief performance deteriorates
Solution Approach 1:
The sealing function and strain relief function are segmented into different elements. The sealing element is made from elastic/soft material that deforms onto the cable to provide effective sealing, while the clamping element with rigid balls provides the strain relief function. This segmentation allows the sealing element to be soft without compromising strain relief, as the rigid clamping element handles that function.
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 simple, cost-effective, and easy-to-assemble cable gland with high strain relief and sealing efficacy, suitable for a wide range of cable diameters, maintaining tightness across varying temperatures and reducing material stress on the sealing insert, ensuring reliable performance.
Implementation Method 1
spherical pressure elements (8), which are displaced by the pressure screw (2) in the direction of the cable (4) and thus pressed against the cable (4)
Implementation Method 2
elastic sealing insert (5), through which the cable (4) is guided
Data Source
Figure 1~1a
Figure 2
Figure 3~4
AI summary
Cable gland with a base body 1 and a pressure screw 2, wherein the base body 1 has an external thread 3 matching an internal thread of the pressure screw 2 and an interior for the passage of a cable 4, wherein the cable 4 is guided through an elastic sealing insert 5 and a clamping cage 6, wherein the inner contour of the pressure screw 2 is pressed against the elastic sealing insert 5 and the clamping cage 6 when tightened, wherein the clamping cage 6 is formed in one piece and has film hinges 7 arranged along a circular ring, which are displaced by the pressure screw 2 in the direction of the cable 4, wherein spherical pressure elements 8 are arranged at the ends of the film hinges 7, which are pressed onto the cable 4 by a first pressure point in the pressure screw 2 when the pressure screw 2 is tightened, and the elastic sealing insert 5 is pressed onto the cable 4 by a second pressure point in the pressure screw 2.wherein the clamping cage 6 with the film hinges 7 and the spherical pressure elements 8 is designed as a one-piece molded part.