Superconducting Cable Terminal With Three-Stage Metal Sleeve

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Solution Overview

Problem

Conventional terminal structures for superconducting cable conductors suffer from mechanical damage due to stress concentration and thermal expansion, leading to flexure and potential fracture at the connection region between the superconducting layers and insulating sheath, especially under bending and thermal cycling.

Innovation Solution

A terminal structure featuring a metal sleeve with a three-stage cylindrical design, where the first portion is in close contact with the central support, the second portion is soldered around the superconducting layers, and the third portion securely contains the insulating layer, preventing flexure and stress concentration, and accommodating thermal expansion through a diameter-increasing and potentially slitted design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the insulating layer and superconducting layer are removed to expose the central support and superconducting layer for terminal connection, then electrical connection is enabled, but mechanical damage occurs due to stress concentration and thermal expansion

Engineering Contradiction:
Improveelectrical connection reliabilityVSAvoidmechanical strength at connection region
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent employs a nested structure where the metal sleeve is divided into three cylindrical portions that fit concentrically around the central support, superconducting layer, and insulating layer respectively. This nested arrangement allows each layer to be contained and protected within the terminal structure, preventing mechanical damage while maintaining electrical connection. The first cylindrical portion fits around the central support, the second around the superconducting layer, and the third around the insulating layer, creating a protective nested configuration.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent applies different functional properties to different portions of the metal sleeve. The first cylindrical portion is designed for close contact with the central support to provide mechanical stability, the second cylindrical portion is soldered to the superconducting layer for electrical connection, and the third cylindrical portion contains the insulating layer for insulation. This local differentiation of properties allows each region to fulfill its specific function while collectively solving the contradiction between electrical connection and mechanical strength.

Inventive Principle:
Principle #3Local quality

2Reliability

If solder is applied to connect superconducting layers with Cu electrode, then low connection resistance is achieved, but large force is applied to superconducting tape during thermal shrinkage and installation

Engineering Contradiction:
Improveelectrical connection qualityVSAvoidmechanical stress on superconducting tape
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The nested three-stage cylindrical structure distributes mechanical stress across multiple concentric layers. The central support bears the primary mechanical load from thermal shrinkage and installation tension, while the superconducting layer is protected within the second cylindrical portion. This nested configuration isolates the superconducting tape from direct mechanical stress while maintaining the solder connection for electrical conductivity.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The central support acts as an intermediary that absorbs and transfers mechanical forces away from the superconducting layer. During thermal shrinkage and installation, the central support bears the tensile stress, preventing direct force application to the brittle superconducting tape. The metal sleeve serves as another intermediary, providing a flexible connection that accommodates thermal expansion and contraction while maintaining electrical contact.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 mechanically robust and electrically reliable connection with low resistance, preventing damage from stress and thermal expansion, ensuring stable current flow and maintaining structural integrity under varying temperatures.

Implementation Method 1

a second cylindrical portion which is soldered around an exposed portion of the superconducting layer

Methodology Applied
Scientific EffectSoldering: Soldering

Implementation Method 2

a superconducting cable which transmits electricity with low loss

Methodology Applied
Scientific EffectSuperconductivity: Superconductivity

Implementation Method 3

high tensile stress is applied to the electrode and the superconducting cable conductor due to a thermal shrinkage of the superconducting cable

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentEP2565987B1Terminal structure and terminal member of superconducting cable conductor
Publication Date: 2016.05.04 FURUKAWA ELECTRIC CO LTD
  • EP2565987B1 patent drawingFigure 1~2
  • EP2565987B1 patent drawingFigure 3A~3B
  • EP2565987B1 patent drawingFigure 3C~3D

AI summary

Disclosed are a terminal structure and a terminal member for a superconducting cable conductor, wherein the mechanical strength is increased and electric connection resistance is decreased in the connecting part between the superconducting cable conductor and the terminal member. In the structure connecting a terminal part (10) of a superconducting cable conductor with a metal sleeve (30) which also serves as a terminal member for a good conductor, the terminal part (10) is provided with a superconducting layer (12) arranged on the outer periphery of a center supporting body (11) and an insulating body layer (13) surrounding the superconducting layer, wherein the insulating layer (13) and the superconducting layer (12) are stripped such that the center supporting body (11) and the superconducting layer (12) are exposed in order from the end part. The metal sleeve (30) is provided with a first cylinder part (31) the inner surface (3a) of which comes into close contact with the exposed part of the center supporting body (11), a second cylinder part (32) the inner surface (3b) of which is soldered to the exposed part of the superconducting layer (12), and a third cylinder part (33) into the inside of which is inserted the insulating body layer (13).