Ultrasonic-Welded Bushing Connections to Prevent Partial Discharge
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Solution Overview
Problem
Existing methods for forming internal connections in bushings, particularly high voltage bushings, face challenges such as the use of toxic flux in soldering and mechanical fasteners that are not suitable for all conductive elements, leading to electrical failures and partial discharge issues.
Innovation Solution
The use of ultrasonic welding joints to mechanically and electrically connect conductive elements without intermediate substances, allowing for connections between various metals and foils, including Cu-to-Cu and Al-to-Cu, with a structured welding tool to enhance joint integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soldering is used to form internal connections in bushings, then electrical conductivity is improved, but toxic flux and heating requirements cause reliability issues and limit applicability
Solution Approach 1:
The patent replaces the thermal-based soldering process with ultrasonic welding, which uses mechanical vibrations in the ultrasonic frequency range to join conductive elements. This substitution eliminates the need for toxic flux and avoids heating conductive elements near their melting points, thereby improving reliability while removing harmful thermal and chemical effects
Solution Approach 2:
The invention applies ultrasonic vibrations to the conductive elements during the joining process. These high-frequency mechanical vibrations generate friction and heat localized at the interface between elements, enabling metallurgical bonding without bulk heating. This resolves the contradiction by providing reliable electrical connections through mechanical vibration rather than thermal processing
2Ease of manufacture
If mechanical fasteners are used to connect conductive elements, then assembly is simplified, but protrusions cause partial electrical discharge in electrically stressed areas
Solution Approach 1:
The patent replaces mechanical fastening systems with ultrasonic welding, which creates direct metallurgical bonds between conductive elements. This eliminates protruding fastener components that could cause partial electrical discharge, while the welding process itself remains relatively simple to implement. The solution resolves the contradiction by substituting a different joining mechanism that avoids the discharge problem entirely
Solution Approach 2:
The ultrasonic welding process creates localized bonds at the interface between conductive elements without requiring protruding components. The joint area has different properties (direct metal-to-metal contact) compared to the surrounding areas, ensuring smooth surfaces that prevent electrical discharge while maintaining ease of manufacture through a streamlined process
3Strength
If conventional welding is used on foils, then strong joints are achieved, but the foil melts or burns due to high temperature
Solution Approach 1:
The patent uses ultrasonic vibrations to generate localized friction and heat at the foil interface during welding. The high-frequency mechanical energy is converted to heat only at the contact surfaces, enabling strong metallurgical bonds without raising the bulk temperature of the foil. This resolves the contradiction by confining thermal effects to the immediate joint area while maintaining overall low temperature
Solution Approach 2:
The invention changes the welding parameters by using ultrasonic frequency vibrations instead of conventional thermal heating. This parameter change allows the welding process to occur at temperatures well below the melting point of the foil material, achieving strong joints without thermal damage. The process transforms the welding mechanism from thermal diffusion to vibration-induced friction and localized bonding
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
Ultrasonic welding reduces the risk of electrical failure by maintaining low impedance and preventing partial discharge, enabling reliable connections even in proximity to plastics, with lower impedance compared to solder joints.
Implementation Method 1
an at least partially by means of application of vibrations in the ultrasonic bandwidth from an external energy source
Implementation Method 2
The resulting surface friction causes diffusion of the material of one of the conductive elements into the other
Implementation Method 3
The resulting surface friction causes diffusion of the material of one of the conductive elements into the other
Data Source
AI summary
The bushing includes a plurality of electrically conductive elements and at least one ultrasonic welding joint. The at least one ultrasonic welding joint is formed between one electrically conductive element and another electrically conductive element and mechanically and electrically connects the electrically conductive elements with each other.