Spiral Vacuum Capacitor Electrode Geometry for Stable Brazing
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Solution Overview
Problem
State-of-the-art vacuum capacitors face limitations in withstanding higher voltages without increasing size, as the use of high melting point materials for electrode units leads to collapse during the brazing process, restricting the use of highly conductive supporting materials like copper with spiral wound band-shaped capacitor plates made of materials like stainless steel.
Innovation Solution
An electrode unit design featuring a spiral wound band-shaped capacitor plate with an inclined edge forming an angle less than or equal to 45° with its longitudinal axis, allowing for the use of both highly conductive supporting materials and high melting point materials without collapsing during brazing, and employing non-overlapping braze filler materials for multiple brazing steps to ensure reliable assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high melting point materials are used for spiral wound band-shaped capacitor plates, then voltage withstanding capability is improved, but the electrode units collapse during the brazing process
Solution Approach 1:
The patent changes the geometric parameter of the capacitor plate by introducing an inclined edge with a specific angle range (10° to 45°). This parameter change allows the high melting point material to maintain structural stability during brazing while preserving its voltage withstanding capability, resolving the contradiction between strength and reliability.
2Temperature
If copper supporting parts are used, then heat conduction is improved, but thermal stress causes failure during brazing with high melting point materials
Solution Approach 1:
The patent creates a composite structure combining copper supporting parts with spiral wound band-shaped capacitor plates made of high melting point materials. The inclined edge geometry of the capacitor plate reduces thermal stress concentration at the interface, allowing the composite structure to maintain both excellent heat conduction from the copper and thermal stress resistance from the high melting point material configuration.
3Strength
If electrode separation is increased to withstand higher voltages, then voltage capability is improved, but the capacitor size increases
Solution Approach 1:
The patent changes the geometric parameters of the capacitor plate, specifically the inclined edge angle and the spiral winding configuration, to optimize the electric field distribution. This allows achieving higher voltage capability without proportionally increasing the capacitor size, as the inclined edge geometry enables more efficient voltage withstanding at compact dimensions.
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
Enables the creation of vacuum capacitors that can withstand higher working voltages and currents while maintaining compact size, avoiding thermal stress-induced failures and allowing for efficient heat transport, thus optimizing the performance and reliability of vacuum capacitors.
Implementation Method 1
copper is generally seen as a good material for electrodes or electrode units because it has low electric losses. Even with very high RF currents, vacuum capacitors generate only modest heat which can easily be transported away from the electrodes to the collars of the enclosure by heat conduction
Implementation Method 2
the band-shaped capacitor plate comprises a first longitudinal edge attached to a supporting part and a second longitudinal edge, the second longitudinal edge being free, wherein at the outer extremity of the spiral, the first longitudinal edge and the second longitudinal edge are connected by an inclined edge
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
The present invention relates to an electrode unit (10, 20) for an electric vacuum capacitor comprising a band-shaped capacitor plate (11, 21) with a height H, wherein the band-shaped capacitor plate (11, 21) is wound in a spiral with a maximum diameter Dmax and a constant distance between successive turns, wherein the band-shaped capacitor plate (11, 21) comprises a first longitudinal edge (11a, 21a) attached to a supporting part (12) and a second longitudinal edge (11b, 21b), the second longitudinal edge (11b, 21b) being free, wherein at the outer extremity of the spiral, the first longitudinal edge (11a, 21a) and the second longitudinal edge (11b, 21b) are connected by an inclined edge (11c, 21c) such that the first longitudinal edge (11a, 21a) is longer than the second longitudinal edge (11b, 21b), wherein the inclined edge (11c, 21c) forms with the longitudinal axis (B) of the band-shaped capacitor plate (11, 21) an angle α less than or equal to an angle αmax = (45°·π/180°). The invention relates also to a vacuum capacitor (30) comprising at least one electrode unit (10, 20) according to the present invention.