Bellows-Centered Vacuum Interrupter Assembly for Vacuum Sealing

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Solution Overview

Problem

Existing vacuum switching tubes face challenges in simple and cost-effective mounting of the moving contact rod and fixing of the bellows, with complex centering and vacuum sealing requirements.

Innovation Solution

A vacuum switching tube design featuring a corrugated metal bellows with a bellows base that allows axial movement of the moving contact rod, integrated with a centering element and a through-opening for the rod, eliminating the need for additional centering devices and ensuring vacuum-tight sealing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the contact rod is made of copper or copper alloy to ensure good electrical conductivity, then the electrical conductivity is improved, but the oxidation resistance deteriorates

Engineering Contradiction:
Improveelectrical conductivityVSAvoidoxidation resistance
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The contact rod uses a composite structure with a copper or copper alloy core providing electrical conductivity, and an outer layer (such as nickel, chromium, or other oxidation-resistant materials) providing oxidation resistance. This composite material approach resolves the contradiction by combining materials with complementary properties - the copper core ensures good electrical conductivity while the outer protective layer prevents oxidation.

Inventive Principle:
Principle #40Composite materials

2Volume of moving object

If the vacuum interrupter is designed for compactness to reduce size, then the volume is reduced, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvevolume of vacuum interrupterVSAvoidmanufacturing precision
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The vacuum interrupter is divided into modular components including separate contact rods, insulating pillars, and arc extinguishing chambers. This segmentation allows each component to be manufactured and assembled independently, reducing the overall complexity and precision requirements while achieving compact dimensions through optimized spatial arrangement of the modular parts.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The contact rod employs a tapered design where the diameter varies along its length, with the arc contact portion having a smaller diameter than the upper portion. This dimensional variation optimizes the arc extinguishing performance while maintaining compact overall dimensions, and the gradual transition reduces manufacturing precision requirements compared to sharp geometric changes.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Length of moving object

If the contact rod diameter is reduced to minimize arc discharge distance, then the arc discharge distance is shortened, but the current carrying capacity deteriorates

Engineering Contradiction:
Improvearc discharge distanceVSAvoidcurrent carrying capacity
Core Design Contradiction:
Length of moving objectVSReliability

Solution Approach 1:

The contact rod features a tapered diameter design where the diameter varies along the length. The arc contact portion has a smaller diameter to minimize arc discharge distance, while the upper portion has a larger diameter to ensure sufficient current carrying capacity. This dimensional variation along the length dimension resolves the contradiction between short arc distance and high current capacity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The contact rod uses composite materials or coated structures where the arc contact region is optimized for minimal arc distance, while other portions of the rod maintain larger dimensions or use materials optimized for current carrying. This allows different sections to be optimized for different functions, resolving the contradiction between arc distance and current capacity.

Inventive Principle:
Principle #40Composite materials

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

Simplifies the mounting process, reduces manufacturing complexity and costs, and maintains vacuum integrity by integrating the bellows base and centering in a single step, avoiding gas leaks and additional components.

Implementation Method 1

a vacuum interrupter (1) having a insulating case (11) made of a transparent or translucent material

Methodology Applied
Scientific EffectVacuum: Vacuum

Implementation Method 2

an arc extinguishing chamber (21) provided with a pair of contacts (22, 23) for establishing or interrupting a current flow

Methodology Applied
Scientific EffectElectric Arc: Electric Arc

Data Source

PatentEP4244878B1Vacuum interrupter
Publication Date: 2026.04.15 SIEMENS AG
  • EP4244878B1 patent drawingFigure 1
  • EP4244878B1 patent drawingFigure 2
  • EP4244878B1 patent drawingFigure 3

AI summary

The vacuum interrupter (1) according to the invention has a cover bottom (16) which comprises an insertion opening (17) for a moving contact rod (9) which is axially movable and carries a moving contact (4). The moving contact rod (9) is guided out of the vacuum interrupter (1) in a vacuum-tight manner by means of a bellows (12). The bellows (12) has a centering shoulder (122) which is formed by a tubular end piece of the bellows (12) extending in parallel with the longitudinal axis (129) of the bellows (12) and which is inserted into the insertion opening (17). The bellows (12) additionally has a bellows bottom (123) which is located on the centering shoulder (122), extends substantially transversely to the longitudinal axis (129) of the bellows (12) and has a through-opening (126) for the moving contact rod (9).