Asymmetric Traction Reactor Core for Lower Train Noise
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Solution Overview
Problem
Current traction reactors exhibit high noise radiation due to their fully symmetric mechanical structure and symmetric force distribution, which strongly excite a structural vibration mode around 2500 Hz, leading to poor sound environments in train compartments.
Innovation Solution
A structurally asymmetric reactor core is introduced, where the arrangement of air gaps and connecting joints is asymmetrical with regard to at least one center plane, transforming the monopole-like vibration mode into a less noise-efficient dipole-like mode, thereby reducing noise emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a symmetric mechanical structure with symmetric force distribution is used, then the reactor core is mechanically stable and easy to manufacture, but it strongly excites a structural vibration mode around 2500 Hz leading to high noise radiation
Solution Approach 1:
The patent applies asymmetry by introducing an asymmetric arrangement of air gaps in the reactor core structure. Specifically, the air gaps are positioned at different locations and/or have different dimensions on opposite sides of the core, breaking the symmetric force distribution while maintaining mechanical stability. This asymmetric configuration prevents the excitation of the problematic three-fold symmetric vibration mode around 2500 Hz, thereby reducing noise radiation without compromising manufacturability
2Strength
If a symmetric force distribution is maintained, then the structural integrity is preserved, but the acoustic monopole-like mode vibration pattern produces very high radiation efficiency
Solution Approach 1:
The patent introduces asymmetric air gap arrangements that create asymmetric force distributions within the reactor core. This asymmetry transforms the acoustic monopole-like vibration mode into a dipole-like mode, which has lower radiation efficiency. The asymmetric configuration is designed to maintain structural integrity by keeping the air gaps within acceptable dimensional tolerances and ensuring proper mechanical support, while effectively reducing the radiation efficiency of vibrational modes
3Object-generated harmful factors
If the air gaps are arranged asymmetrically, then the monopole-like vibration mode is transformed into a dipole-like mode reducing noise emissions, but the structural asymmetry increases manufacturing complexity
Solution Approach 1:
The patent implements a controlled asymmetric arrangement of air gaps where the asymmetry is deliberately designed to transform the vibration mode from monopole-like to dipole-like, reducing noise emissions. The complexity is managed by maintaining a limited number of asymmetric features (specifically the air gap positions and dimensions) rather than making the entire structure asymmetric, thus achieving noise reduction with minimal increase in manufacturing complexity
4Stability of the object's composition
If symmetric coil arrangement is used, then the magnetic field distribution is uniform, but it generates symmetric force distributions that excite high-noise vibration modes
Solution Approach 1:
The patent maintains the symmetric coil arrangement for uniform magnetic field distribution but introduces asymmetric air gap arrangements in the magnetic circuit. This creates asymmetric magnetic force distributions that prevent the excitation of symmetric vibration modes. The asymmetric air gaps are positioned and dimensioned to create differential magnetic forces that counteract the symmetric force distribution from the coils, thereby reducing vibration mode excitation while preserving magnetic field uniformity
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 structural asymmetry significantly reduces noise emissions from traction reactors by converting the acoustically efficient monopole-like mode into a less efficient dipole-like mode, improving the sound environment in train compartments.
Implementation Method 1
The asymmetry transforms the monopole-like mode of vibration of an operating traction reactor comprising the reactor core, into a less noise-efficient dipole-like mode of vibration, thereby reducing noise emissions from a traction reactor comprising the reactor core
Data Source
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AI summary
A reactor core (1) for a traction reactor (2) of an electric power device (3), the reactor core (1) comprising a first limb (10) and a second limb (12) comprising a plurality of gaps (14), a first yoke (16) and a second yoke (18), a plurality of connecting joints (20) formed by connections between the first yoke (16) and each of the first limb (10) and the second limb (12), and by connections between the second yoke (18) and each of the first limb (10) and the second limb (12). The reactor core (1) further comprises an asymmetry with regard to a first center plane (A) and/or with regard to a second center plane (B) by an asymmetrical arrangement of the plurality of gaps (14), and/or by an asymmetrical arrangement of the plurality of connecting joints (20), with regard to the first center plane (A) and/or with regard to the second center plane (B).