Spiral Conductive Shield for Flexible Heating Cable
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Solution Overview
Problem
Existing heating cables for underfloor applications face challenges in meeting safety standards for earthing sharp objects and withstanding impacts while being cost-effective and flexible, as they often require expensive braiding or inflexible metal sheaths to achieve the necessary current carrying capacity and mechanical resilience.
Innovation Solution
A heating cable design featuring a conductive shield formed in a spiral configuration with a conductive conduit, where the spiral turns are separated by less than 2mm and 0.1mm, allowing for a flexible and cost-effective earth shielding that meets safety standards by ensuring a pin is earthed before contacting the core conductor and providing sufficient current carrying capacity, along with a conductive conduit that enhances mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic braiding is used for earth shielding, then current carrying capacity and flexibility are improved, but manufacturing cost and time consumption increase
Solution Approach 1:
The earth shielding is divided into multiple discrete spiral turns rather than continuous braiding. Each turn is separated by a small gap (0.1-2mm), creating a segmented structure that maintains electrical continuity through the gaps while simplifying manufacturing. This segmentation allows the shield to meet current carrying capacity requirements without requiring complex continuous braiding processes.
Solution Approach 2:
The shielding structure transitions from static continuous braiding to a dynamic spiral configuration where turns can be spaced apart. This dynamic arrangement allows flexibility in manufacturing while maintaining functional integrity, enabling easier production without compromising the earth shielding effectiveness or current carrying capacity.
2Ease of manufacture
If continuous metal sheath is used for earth shielding, then manufacturing cost is reduced, but flexibility deteriorates
Solution Approach 1:
Instead of a continuous rigid metal sheath, the earth shielding is segmented into discrete spiral turns with gaps between them. This segmentation transforms the structure from rigid and inflexible to flexible and adaptable, while still providing continuous electrical grounding through the closely spaced turns (0.1-2mm separation).
Solution Approach 2:
The spiral configuration with small gaps between turns creates a flexible shielding structure that can bend and flex like thin films, unlike rigid continuous metal sheaths. This flexible spiral structure maintains electrical continuity while enabling the cable to adapt to various installation configurations and movements.
3Adaptability or versatility
If spiral configuration with separated turns is used, then flexibility and manufacturing ease are improved, but electrical continuity may be compromised
Solution Approach 1:
The local quality of the spiral turns is optimized by controlling the gap size (0.1-2mm) to ensure electrical continuity. The turns are positioned and sized such that each local segment provides sufficient grounding capability, while the cumulative effect of multiple segments ensures overall electrical continuity along the cable length without requiring direct physical contact between turns.
Solution Approach 2:
The spiral configuration uses more turns than a single continuous sheath would provide, creating redundant grounding paths. This excessive action ensures that even with gaps between turns, the cumulative electrical continuity is sufficient to meet safety standards, while the partial coverage of each individual turn maintains flexibility.
4Reliability
If sufficient current carrying capacity is achieved through traditional methods, then safety standards are met, but cable flexibility and cost-effectiveness deteriorate
Solution Approach 1:
The earth shielding is segmented into discrete spiral turns rather than requiring continuous heavy braiding. This segmentation reduces the total amount of conductive material needed while maintaining safety compliance through the cumulative effect of multiple closely spaced turns (0.1-2mm separation), thereby reducing cost and improving flexibility.
Solution Approach 2:
The design changes key parameters of the shielding structure: turning from continuous braiding to discrete spiral turns, controlling turn separation distance (0.1-2mm), and optimizing turn density. These parameter changes enable the cable to meet safety standards with less material, reducing complexity and cost while maintaining or improving flexibility.
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 results in a heating cable that is both flexible and cost-effective, meeting safety standards for earthing and impact resistance without the high material costs and manufacturing complexities of traditional braiding methods, while maintaining the ability to withstand significant impacts without compromising insulation integrity.
Implementation Method 1
a conductive shield extending along the cable and surrounding said at least one conductor, at least a portion of said conductive shield comprising a shielding conductor extending in a spiral around said at least one conductor
Implementation Method 2
In some types of heating cable, the conductors act as resistive heating elements
Data Source
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AI summary
A heating cable (10) and a method of manufacturing a heating cable (10). The heating cable (10) comprises at least one conductor (12a,12b) extending along the cable (10), a conductive shield extending along the cable (10), and surrounding said at least one conductor (12a,12b); and at least one insulating separation layer (14a,14b) separating the conductive shield from said at least one conductor (12a,12b). At least a portion of said conductive shield comprises a shielding conductor (16) extending in a spiral around said at least one conductor (12a,12b), the spiral comprising a plurality of turns (16a-e), each turn (16a-e) being physically separated from a corresponding portion of an adjacent turn (16a-e).