Vacuum Interrupter Lever Mechanism for Low-Friction Contact Switching

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Solution Overview

Problem

Existing mechanisms for transmitting motion from a driving cam to the contact rod of a vacuum interrupter in power diverter switches face challenges in ensuring stable and reliable switching of electrical contacts due to alignment issues, wear, and friction-related problems.

Innovation Solution

A system utilizing a main driving shaft coupled to a control cam, with a transmission unit comprising a lever mechanism and rollable guiding elements, including a fork-shaped lever and rolling bearings, to transmit motion to the contact rod, providing precise guidance and reducing friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional transmission mechanism is used to transmit motion from the driving cam to the contact rod, then the structure is simpler, but the alignment precision and reliability of contact rod movement deteriorate due to friction and wear

Engineering Contradiction:
Improvereliability of contact switchingVSAvoidcomplexity of transmission mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The transmission mechanism is segmented into distinct functional components: the driving cam, the fork-shaped lever, and the rollable guiding elements. This segmentation allows each component to perform its specific function optimally - the cam generates motion, the lever transmits and directs it, and the guiding elements ensure precise alignment while reducing friction through rolling contact.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent replaces sliding friction-based mechanical transmission with rolling friction-based transmission by introducing rollable guiding elements. These elements convert harmful sliding friction into beneficial rolling friction, significantly reducing wear and improving reliability while maintaining a relatively simple mechanical structure.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Stability of the object's composition

If sliding friction-based transmission is used, then the structure is simpler, but wear and alignment stability deteriorate

Engineering Contradiction:
Improvealignment stability of contact rodVSAvoidmanufacturing complexity of transmission unit
Core Design Contradiction:
Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The rollable guiding elements act as intermediaries between the fork-shaped lever and the contact rod. These intermediary elements mediate the force transmission while maintaining stable alignment through their rolling motion, preventing direct sliding contact that would cause wear and misalignment.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Volume of moving object

If a compact design is pursued, then the space requirement is reduced, but the mechanism complexity increases to achieve precise guidance

Engineering Contradiction:
Improvevolume of transmission mechanismVSAvoidcomplexity of guiding mechanism
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The patent merges multiple functions into the fork-shaped lever and rollable guiding elements combination. The lever provides both force transmission and directional guidance, while the guiding elements simultaneously constrain motion and reduce friction. This merging achieves precise guidance in a compact configuration without requiring separate complex guiding mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

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

Enables secure and reliable switching of electrical contacts with reduced friction, allowing for misalignment compensation and easy adjustment, resulting in a compact and simple design with improved manufacturing and assembly efficiency.

Implementation Method 1

a rotation of the control cam 13 generated by the main driving shaft 10 causes a movement of the contact rod 31 due to a guided rotation of the fork-shaped lever 22 by means of rolling of the guiding elements

Methodology Applied
Scientific EffectRolling friction: Friction

Data Source

PatentEP3989252B1System for controlling a vacuum interrupter for a power diverter switch, a power diverter switch and an on-load tap changer
Publication Date: 2026.02.25 HITACHI ENERGY LTD
  • EP3989252B1 patent drawingFigure 1
  • EP3989252B1 patent drawingFigure 2
  • EP3989252B1 patent drawingFigure 3

AI summary

A system (1) for controlling a vacuum interrupter (30) for a power diverter switch comprises a main driving shaft (10) which is configured to drive the control cam (13). The system (1) further comprises the vacuum interrupter (30) which is configured to separate electrical contacts in a vacuum by use of a contact rod (31), and a transmission unit (20) which is configured to transmit the force generated by the main driving shaft (10) to the contact rod (31). The transmission unit (20) comprises a lever mechanism with a plurality of rollable guiding elements (25, 26) and a rotatable forkshaped lever (22), the lever mechanism is coupled to both the control cam (13) and the contact rod (31) of the vacuum interrupter (30) such that a rotation of the control cam (13) generated by the main driving shaft (10) causes a movement of the contact rod (31) due to a guided rotation of the forkshaped lever (22) by means of rolling of the guiding elements (25, 26).