Railway Vehicle Bushing Structure for Compact Cable Insulation
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Solution Overview
Problem
Existing bushing units for railway vehicles are oversized due to the overlap of earth electrodes and arrangement surfaces, leading to space constraints in limited installation areas.
Innovation Solution
A bushing unit design with an embedded earth electrode and flange member configuration that reduces the protrusion into the equipment box, utilizing a tapered inner conductor and electric field shielding layer to minimize size and ensure electrical insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the earth electrode extends to overlap with the arrangement surface in the radial direction, then electrical field shielding is improved, but the bushing size increases
Solution Approach 1:
The earth electrode is repositioned from a radial overlap configuration to an axial extension configuration. The electrode now extends axially beyond the arrangement surface rather than radially overlapping it, maintaining shielding effectiveness while reducing the bushing's radial dimensions and overall size.
Solution Approach 2:
The spatial parameters of the earth electrode are changed by modifying its position and orientation relative to the arrangement surface. By extending the electrode axially rather than having it overlap radially, the bushing can be made more compact while preserving the electrical field shielding function.
2Volume of moving object
If the bushing size is reduced to fit smaller installation spaces, then space utilization is improved, but the electrical insulation performance may deteriorate
Solution Approach 1:
The design shifts from radial dimension optimization to axial dimension optimization. By extending the earth electrode axially, the bushing's radial size can be reduced for compact installation while the axial extension maintains sufficient electrical insulation distance and shielding effectiveness.
Solution Approach 2:
Different regions of the bushing are optimized for different functions: the radial dimension is minimized for compact installation space, while the axial dimension is extended to maintain electrical insulation performance. The earth electrode's axial extension provides localized shielding without increasing overall bushing volume.
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 a compact bushing unit that fits within smaller installation spaces, maintaining electrical insulation and reducing the need for larger attachment holes, suitable for railway vehicle applications.
Implementation Method 1
By providing the earth electrode, it is possible to shield an electric field on the inner circumferential side of the earth electrode and it is thereby possible to reduce electric field strength around the bushing
Data Source
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AI summary
A bushing unit (1) includes an inner conductor (22) adopted to be electrically connected to an end of a power cable (71), a bushing (21) covering the inner conductor, and an earth electrode (23) that is embedded in the bushing and surrounds the inner conductor. An inner circumferential surface of the bushing includes an arrangement surface (212) on which a stress cone (73) attached to the power cable is arranged. When one side of the inner conductor configured to be connected to the end of the power cable is defined as a proximal end side and a side opposite to the proximal end side is defined as a distal end side, an end of the earth electrode on the proximal end side is located on the distal end side relative to the arrangement surface.