High-Voltage Bushing Joints Using Ultrasonic Welding
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Solution Overview
Problem
High voltage bushings face failures due to high electrical impedance at internal joints, particularly with existing methods like soldering and mechanical fasteners, which are ineffective for connections involving foils and can cause partial electrical discharges.
Innovation Solution
The use of ultrasonic welding joints between electrically conductive elements, which form a mechanically and electrically sound connection without intermediate substances, allowing for connections in close proximity to plastics and reducing the risk of electrical failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soldering is used to connect conductive elements, then electrical connection is achieved, but it cannot be used on connections other than Cu-to-Cu joints and requires toxic flux and metals
Solution Approach 1:
The patent replaces the chemical soldering process with ultrasonic welding, which uses mechanical vibration energy to join conductive elements. This substitution eliminates the need for flux and solder materials, enabling universal application across different metal combinations including Cu-to-Al, Cu-to-Cu, and Al-to-Al connections without material compatibility restrictions.
Solution Approach 2:
The invention changes the joining parameters from thermal-chemical (soldering temperature and flux chemistry) to mechanical-vibrational (ultrasonic frequency and amplitude). This parameter transformation allows the process to work on any conductive material combination while eliminating toxic substances, achieving both universal adaptability and reliable electrical connection.
2Strength
If mechanical fasteners are used to connect conductive elements, then mechanical connection is achieved, but they cannot be used on foils due to large size relative to foil thickness and protrusions can cause partial electrical discharge
Solution Approach 1:
The patent replaces mechanical fastening systems with ultrasonic welding, which uses high-frequency mechanical vibrations to create metallurgical bonds. This eliminates the need for physical fasteners that protrude into electrically stressed areas, thereby preventing partial electrical discharge while maintaining strong mechanical and electrical connections, especially suitable for thin foil applications.
Solution Approach 2:
The invention applies mechanical vibration at ultrasonic frequencies to join conductive elements. The vibrational energy generates friction and heat at the contact interface, creating a strong metallurgical bond without requiring protruding fasteners. This vibration-based joining method produces flush, smooth joints that eliminate electrical discharge risks while providing adequate mechanical strength.
3Strength
If traditional welding methods are used, then strong joints are formed, but high temperatures can melt or burn foils
Solution Approach 1:
The patent employs ultrasonic vibration to generate localized friction and heat at the joint interface during welding. This concentrated vibrational energy creates strong metallurgical bonds with minimal overall temperature increase, preventing the melting or burning of thin foil materials while achieving joint strengths comparable to or exceeding traditional welding methods.
Solution Approach 2:
The invention uses periodic ultrasonic vibrations at high frequency (typically 20-40 kHz) to progressively build up the weld joint. The periodic nature of the vibration allows for controlled energy input, creating strong bonds through repeated friction cycles without causing thermal damage to temperature-sensitive materials like thin foils.
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 provides reliable, low-impedance connections that prevent high current transients and are effective for various conductive materials, including foils, enhancing the electrical integrity and durability of high voltage bushings.
Implementation Method 1
Ultrasonic welding involves high-frequency vibrations being transmitted into the conductive elements to be welded
Implementation Method 2
The resulting surface friction causes diffusion of the material of one of the conductive elements into the other
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
The bushing (100) comprises a plurality of electrically conductive elements (1, 2a..2c, 3, 4, 6) and at least one ultrasonic welding joint (10). 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.