Vacuum Interrupter Twist Protection via Plastic Ring
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Solution Overview
Problem
Existing vacuum interrupters with twist protection mechanisms are costly and do not provide optimal performance in reducing friction and torque-related issues during the assembly and operation of contactor and load break switches.
Innovation Solution
A ring-shaped plastic part with complementary spanner flats is used to guide the movable contact stem, fixed externally to the vacuum interrupter, and secured to the metal lid using a self-tapping screw, allowing for effective twist protection without the need for additional tooling and enhancing the structural fixation through a circular ring slot and tube-like section design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a twist protection mechanism with spanner flats and grease application is implemented, then friction reduction and guidance are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the twist protection function from the complex assembly of spanner flats, grease application, and alignment features, implementing it through a simple ring-shaped plastic part with a central opening that guides the movable contact stem without requiring additional tools or materials
Solution Approach 2:
The patent replaces expensive and complex metal components with grease application with a simple, inexpensive ring-shaped plastic part that provides the same guidance and friction reduction function without requiring maintenance or special assembly tools
2Reliability
If deep drawn metal parts are brazed together for vacuum tight sealing, then reliability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent incorporates an annular entry pilot directly into the deep drawn metal lid during the forming process, which preliminary centers the lid on the ceramic tube before brazing occurs, eliminating the need for separate alignment operations and tooling
Solution Approach 2:
The patent combines the centering function and sealing function into a single integrated metal lid structure with the annular entry pilot, eliminating the need for separate alignment features and reducing the number of assembly steps
3Adaptability or versatility
If a self-tapping screw is used to fix the plastic part at arbitrary angular positions, then adaptability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs a self-tapping screw that creates its own thread in the plastic ring part, allowing the plastic part to be fixed at any angular position without requiring pre-drilled holes, pre-tapped threads, or precise angular alignment features
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
This solution reduces friction and torque-related issues, improving the performance of vacuum interrupters by providing effective twist protection without increasing costs, allowing for assembly without specialized tooling and ensuring a secure fixation of the plastic part using a self-tapping screw, which can be applied at arbitrary angular positions.
Implementation Method 1
the aforesaid self-tapping screw is screwed into the circular slot at an arbitrary angularity
Implementation Method 2
the movable contact stem is guided through an opening of the opposite metal lid via axially extendable vacuumtight bellows
Implementation Method 3
the metal lids are brazed vacuumtightly and circumferentially to the end faces of the insulating tube
Data Source
Figure 1
Figure 2
AI summary
A vacuum interrupter with a movable contact (4) fixed on a movable contact stem (5) and a fixed contact (2) with a fixed contact stem (3) located in an electrically insulating tube (8), which is closed by metal lids (7, 7') at boths ends. The fixed contact stem is placed on one of the metal lids, and the movable contact stem is guided through an opening of the opposite metal lid via an axially extendable bellow (6). In order to create twist-protection of the movable contact stem (4), a ring disc shaped plastic part (11) with a central opening through which the movable contact stem (4) is guided is connected externally to the vacuum interrupter such that inner spanner flats (12) inside the opening of the plastic part (11) complementarily fit external spanner flats (10) of the movable contact stem (5). The plastic part may be fixed by a self-tapping screw (14), and getter-material strips (15) may be arranged in the inner volume of the hollow metal lid (7, 7').