Ceramic PTC Heating Cable Chip Tabs for Overheat Disconnect
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional heating cables that utilize perfluoroalkyl or polyfluoroalkyl substances (PFAS) for embedding positive temperature coefficient (PTC) materials face inefficiencies and environmental concerns, and there is a need for a self-regulating heating solution that mitigates thermal runaway and overheating without relying on polymer-based materials.
Innovation Solution
A self-regulating heating cable design that employs ceramic PTC chips suspended between bus wires using a frame structure, with a frame that includes chip tabs to retain and electrically connect the PTC chips, and incorporates a switch mechanism to disconnect them in case of overheating, all while using inorganic materials for jackets and jackets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If perfluoroalkyl or polyfluoroalkyl substances (PFAS) are used to embed PTC materials, then the heating cable can be manufactured with conventional materials, but environmental concerns arise and the solution relies on polymer-based materials that may contribute to thermal runaway
Solution Approach 1:
The patent changes the material parameter from polymer-based (PFAS) to inorganic-based (ceramic) PTC materials. This parameter change eliminates the environmental harm and thermal runaway risks associated with polymer decomposition while maintaining the heating functionality. The ceramic PTC particles are suspended in an inorganic carrier, fundamentally altering the material composition to be more environmentally benign and thermally stable.
Solution Approach 2:
The patent employs a composite structure combining ceramic PTC particles with an inorganic carrier material. This composite approach allows the beneficial properties of ceramic PTC materials (high temperature stability, environmental benignity) to be integrated into a functional heating cable structure, replacing the conventional polymer-based composite while maintaining manufacturability.
2Power
If chip tabs are used to retain and electrically connect PTC chips, then the heating cable achieves efficient thermal output, but the structure becomes more complex
Solution Approach 1:
The chip tab structure serves multiple functions simultaneously: it provides mechanical retention for the PTC chip, establishes electrical connection between the chip and conductive wires, and maintains structural integrity of the heating element. This multi-functionality reduces the need for separate components, thereby managing complexity while achieving efficient thermal output.
Solution Approach 2:
The patent merges the retention and electrical connection functions into a single integrated chip tab structure. By combining what would traditionally be separate components (retention mechanisms and electrical connectors) into one unified element, the design achieves efficient thermal output without proportionally increasing structural complexity.
3Reliability
If a switch mechanism is incorporated to disconnect PTC chips in case of overheating, then thermal runaway is prevented, but the device complexity increases
Solution Approach 1:
The switch mechanism is designed to automatically respond to temperature conditions without external control. When overheating is detected, the switch automatically opens to disconnect the PTC chip, and can automatically close when temperature normalizes. This self-service capability provides thermal runaway prevention while minimizing the need for complex control systems, external sensors, or manual intervention.
Solution Approach 2:
The switch mechanism utilizes temperature-induced parameter changes in the switching element (such as thermal expansion, phase change, or temperature-dependent conductivity) to automatically open or close the circuit. This parameter-based switching mechanism provides reliable thermal runaway prevention while keeping the overall device complexity manageable, as the switching action is directly coupled to the thermal condition rather than requiring separate sensing and control systems.
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 cable provides efficient thermal output, higher temperature resistance, and effective thermal management by avoiding PFAS, with the switch mechanism preventing thermal runaway and enhancing safety.
Implementation Method 1
current is allowed to flow through the PTC material, thereby generating heat by resistive conversion of electrical energy into thermal energy
Implementation Method 2
As the temperature of the PTC material increases, so does its resistance, thereby reducing the current therethrough and, therefore, the heat generated via resistive heating
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Self-regulating heating cables and associated production methods are provided. A self-regulating heating cable (10) includes a first frame element (32a) coupled to a first conductive wire (12a), with a first chip tab (36a) that extends from the first frame element toward a second conductive wire (12b) at least to a midpoint between the first and second conductive wires. A second frame element (32b) is coupled to the second conductive wire, with a second chip tab (36b) that extends from the second frame element toward the first conductive wire. A ceramic positive temperature coefficient (PTC) chip (14) is disposed between the first conductive wire and the second conductive wire, and is retained between the first conductive wire and the second conductive wire by the first chip tab and the second chip tab.