Twisted Heater Wire Design for Bending Capacity

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Solution Overview

Problem

Conventional heater wires face a trade-off between current carrying capacity and bending capacity, where increasing the cross-sectional area to enhance current carrying capacity significantly decreases bending capacity.

Innovation Solution

A heater wire design featuring multiple twisted heater element wires with a spirally wound rectangular wire around a core wire, accompanied by an insulating sheath, which allows for increased current carrying capacity without increasing the cross-sectional area of each wire, thereby improving bending capacity and maintaining flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the cross-sectional area of the rectangular wire is increased to increase the current carrying capacity, then the bending capacity decreases significantly

Engineering Contradiction:
Improvecurrent carrying capacityVSAvoidbending capacity
Core Design Contradiction:
Quantity of substanceVSStrength

Solution Approach 1:

The heater wire is divided into multiple rectangular wires (e.g., three wires) instead of using a single large wire. Each rectangular wire maintains a small cross-sectional area for good bending capacity, while the collective arrangement of multiple wires provides sufficient current carrying capacity. The wires are twisted together to form a unified heater element that combines the advantages of both small individual wires and large total heating capacity.

Inventive Principle:
Principle #1Segmentation

2Quantity of substance

If the rectangular wire winds tightly around the core wire, then the current carrying capacity increases, but the flexibility and bending capacity decrease

Engineering Contradiction:
Improvecurrent carrying capacityVSAvoidflexibility
Core Design Contradiction:
Quantity of substanceVSEase of operation

Solution Approach 1:

The winding of the rectangular wire around the core wire is designed with controlled looseness rather than tight winding. This dynamic approach allows the wire assembly to maintain flexibility and bendability while still providing sufficient current carrying capacity through the collective cross-sectional area of multiple rectangular wires. The twisted configuration of multiple wires further enhances flexibility while maintaining electrical performance.

Inventive Principle:
Principle #15Dynamics

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 design significantly enhances bending capacity while maintaining or improving current carrying capacity, preventing abnormal heating and maintaining flexibility by canceling internal stress and avoiding tight winding.

Implementation Method 1

A heater wire having a plurality of heater element wires which are arranged so that they twist

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2712265B1Heating wire
Publication Date: 2016.04.27 TOTOKU ELECTRIC CO LTD
  • EP2712265B1 patent drawingFigure 1~2(b)
  • EP2712265B1 patent drawingFigure 3~6
  • EP2712265B1 patent drawingFigure 7~8(b)

AI summary

A heater wire is obtained by twisting together a plurality of heating element wires (10) in which a rectangular wire (2) is spirally wound around a core wire (1), and forming an insulating sheath (3) on an outer peripheral surface of the twisted heating element wires (10). The current carrying capacity can be increased by increasing the number of the heating element wires (10) and there is no need of increasing the cross-sectional area of each of the rectangular wires (2). Therefore, a reduction in the bending capacity due to an increase in the cross-sectional area of the rectangular wires (2) can be avoided, and the bending capacity can be improved significantly.