Liquid-Insulated Bushing With Internal Ribs for Leakage Control
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Solution Overview
Problem
Existing bushings for liquid insulated electrical apparatuses face challenges in providing reliable operation with efficient insulation, mechanical support, and resistance to contamination, while requiring minimal material usage and manufacturing time.
Innovation Solution
A bushing design featuring a thermoplastic insulator body with internal projecting ribs that provide mechanical reinforcement, reduce surface leakage currents, and facilitate easy cleaning, combined with an elastomeric outer cover for enhanced hydrophobicity and chemical bonding, ensuring robust insulation and quick manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the insulator body uses a thin wall structure to reduce material usage, then manufacturing time and material cost are reduced, but mechanical strength and structural stability deteriorate
Solution Approach 1:
The insulator body is segmented into a thin-walled main part and separate reinforcing elements (projecting ribs and circumferential reinforcement elements) that are integrated during molding. This segmentation allows the main structure to use minimal material while strength is provided by discrete reinforcement features.
Solution Approach 2:
The insulator body uses composite construction combining thermoplastic material with reinforcing elements (glass fiber reinforcement or metal inserts) in the reinforcement zones. This creates a composite structure where the thin thermoplastic walls provide insulation while the reinforced zones provide mechanical strength.
2Reliability
If the insulator body has a large external circumference to provide sufficient insulation, then electrical insulation performance is improved, but surface leakage current increases and contamination resistance decreases
Solution Approach 1:
The reinforcement elements extend in the axial dimension rather than requiring increased radial or circumferential dimensions. This allows the insulator to maintain a compact external circumference while achieving the required mechanical strength through axial reinforcement features.
Solution Approach 2:
The insulator body has non-uniform wall thickness and reinforcement distribution - the walls are thinnest where mechanical stress is lowest and thickest where reinforcement elements are located. This local variation in quality provides strength exactly where needed without increasing overall external dimensions.
3Strength
If the insulator body includes outer ribs for reinforcement, then mechanical strength is improved, but contamination resistance and ease of cleaning deteriorate
Solution Approach 1:
The reinforcing elements are nested inside the insulator body rather than protruding outward. The thin-walled main part contains internal reinforcement structures (projecting ribs and circumferential reinforcement elements) that strengthen the insulator without exposing additional surfaces to contamination.
4Strength
If the insulator body uses ceramic material for high strength and temperature resistance, then mechanical strength and thermal stability are improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the material parameter from traditional ceramic to thermoplastic material with glass fiber reinforcement. This parameter change enables the use of injection molding technology, transforming the manufacturing process from complex multi-step ceramic fabrication to a single-step thermoplastic molding process while maintaining adequate mechanical and thermal properties.
Solution Approach 2:
The injection molding process merges multiple functions into a single manufacturing step - the thermoplastic material is molded into the final insulator shape with integrated reinforcement elements, sealing features, and mounting structures all in one operation, eliminating the need for separate assembly steps required by ceramic insulators.
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 achieves reliable mechanical support, reduced surface leakage, and efficient insulation with minimal material usage, while allowing for faster manufacturing and improved contamination resistance.
Implementation Method 1
The thin wall structure of the thermoplastic material makes the time needed for heat transfer through the wall thickness short, in particular the time needed to cool down the molten thermoplastic material until it solidifies in the mold.
Implementation Method 2
combined with an elastomeric outer cover for enhanced hydrophobicity and chemical bonding
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A bushing (100) for a liquid-insulated electrical apparatus (200) is disclosed. The bushing (100) comprises an electrical conductor (101) and an insulator body (110) through which the electrical conductor (101) extends, wherein the insulator body (110) comprises a main part (112) and a plurality of projecting ribs (130), wherein the main part (112) comprises a hollow cylinder shape (113) and wherein the projecting ribs (130) each project radially inwards from the main part (112) and wherein the projecting ribs (130) comprise a main extension (131) along a longitudinal axis (102) of the conductor (101).