Vacuum Capacitor Shoulder Structure for Higher Voltage Capacity
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Solution Overview
Problem
Vacuum capacitors face a risk of uncontrolled discharge due to pointy shapes formed at the outer surfaces during the brazing process, which enhance the electric field and increase the risk of breakdown, especially when integrated into impedance matching networks.
Innovation Solution
The insulating element of the vacuum capacitor housing is modified with a shoulder feature that prevents the braze joints from contacting the outer surface, thereby blocking the flow of braze filler material and reducing the formation of pointy shapes, thus moving the brazing joints away from the highest electrical field area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the brazing process is used to connect collars to the insulating element, then the housing achieves hermetic sealing and structural integrity, but pointy shapes are formed at the outer surface which enhance the electric field and increase the risk of breakdown
Solution Approach 1:
The insulating element is divided into multiple surfaces: a first surface for brazing the collars and a second outer surface that remains free of braze material. This segmentation prevents the harmful pointy shapes from forming on the outer surface while maintaining the structural integrity provided by the brazed joints on the first surface.
Solution Approach 2:
The braze joints are extracted from the outer surface of the insulating element and relocated to a separate first surface. This removes the source of pointy shapes and electric field enhancement from the critical outer surface, eliminating the breakdown risk while preserving the hermetic sealing function.
2Ease of manufacture
If the insulating element is made with equal length at outer and inner diameters for simplicity, then manufacturing is easier, but the brazing joints must contact the outer surface creating safety risks
Solution Approach 1:
The insulating element is segmented into distinct functional surfaces: a first surface dedicated to brazing operations and a second outer surface dedicated to electrical safety. This allows the element to maintain simple manufacturing while achieving the reliability needed for high voltage operation, as the braze material is confined to the first surface and cannot contact the outer surface.
3Reliability
If additional protective means are added to prevent braze material contact with the outer surface, then the risk of uncontrolled discharge is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The functional surfaces are merged into a single integrally formed insulating element rather than using separate protective components. This achieves the reliability of preventing braze material contact with the outer surface while avoiding the additional complexity of separate protective means, as the prevention function is built into the element's geometry itself.
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 design allows for the manufacture of vacuum capacitors with higher voltage capabilities without additional protective means, simplifying the manufacturing process and enhancing safety during voltage conditioning, while reducing the risk of uncontrolled discharges.
Implementation Method 1
Vacuum capacitors are well known in the prior art: a first patent for a vacuum capacitor has been filed by Nikola Tesla in 1896. The original use of a vacuum as the dielectric for a capacitor was to enhance the properties of the capacitor, notably allowing higher voltages to be applied between the capacitor electrodes and higher AC currents to flow through the capacitor as compared to capacitors with other dielectrics. In particular, the electric losses of vacuum are zero
Implementation Method 2
the first conductive collar and the second conductive collar are connected to the insulating element in an air-tight manner by means of a braze material creating a first braze joint and a second braze joint
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
The present invention relates to a vacuum capacitor (100) comprising a housing (105) to contain a vacuum dielectric medium (108), a first electrode (106) and a second electrode (107) separated by said vacuum dielectric medium (108), the housing (105) comprising an insulating element (104), a first conductive collar (102) in electrical contact with the first electrode (106) and a second conductive collar (104) in electrical contact with the second electrode (107), wherein the first conductive collar (102) and the second conductive collar (104) are connected to the insulating element (103) in an air-tight manner by means of a braze material creating a first braze joint (113) and a second braze joint (114), in which the insulating element (103) comprises at least one shoulder (120) which is located so to prevent that the first braze joint (113) and/or the second braze joint (114) are in contact with the outer surface (103a) of the insulating element (103) of the housing (105).