Permanent Magnet Eddy Current Rail Brake Weight Reduction
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Solution Overview
Problem
Existing rail brakes, including adhesion-type and eddy current types, face challenges in generating stable braking forces, especially in adverse weather conditions, and increase the weight of railway vehicles due to the need for electromagnets and large emergency power supplies, while also potentially damaging rails through friction.
Innovation Solution
An eddy current rail brake using permanent magnets with a ferromagnetic support member and a series arrangement of magnets with alternating polarities, allowing for controlled braking force generation without a pole core, reducing weight and improving mountability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If electromagnets are used to generate braking force, then braking force can be generated, but the weight of the rail brake increases due to the need for large emergency power supplies
Solution Approach 1:
The patent extracts and eliminates the power supply system (battery and control circuit) from the rail brake by using permanent magnets instead of electromagnets. The permanent magnets generate the necessary magnetic field without requiring external power, thereby removing the weight of the power supply components while maintaining braking force generation capability through eddy currents in the rail.
Solution Approach 2:
The permanent magnets serve themselves by generating the magnetic field required for braking without needing external power supply. The system uses the kinetic energy of the moving vehicle to generate eddy currents in the rail, which in turn produce the braking force, creating a self-sufficient system that does not require additional power sources.
2Force
If brake shoes are pressed against the rail to generate friction braking force, then braking force is obtained, but the rail is damaged over time
Solution Approach 1:
The patent replaces the mechanical friction-based braking system with an electromagnetic braking system. Instead of pressing brake shoes against the rail to generate friction, the system uses permanent magnets to generate a magnetic field that induces eddy currents in the rail, producing braking force through electromagnetic interaction without mechanical contact, thereby eliminating rail damage from friction.
Solution Approach 2:
The magnetic field acts as an intermediary between the permanent magnets and the rail, transferring energy and producing braking force without direct mechanical contact. The eddy currents induced in the rail serve as the intermediary mechanism that converts magnetic energy into braking force, avoiding the need for physical contact between brake components and the rail.
3Force
If the number of windings of electromagnets is increased to compensate for lack of friction braking force, then braking force is maintained, but the weight of the rail brake increases
Solution Approach 1:
The patent eliminates the need for multiple windings by removing the electromagnet system entirely and replacing it with permanent magnets. The permanent magnets provide the necessary magnetic field strength without requiring winding coils, thereby avoiding the weight increase that would result from increasing the number of windings to compensate for insufficient braking force.
4Force
If adsorption/eddy current rail brake is used, then braking force is generated, but stable braking force cannot be obtained during rain or snow due to friction
Solution Approach 1:
The patent replaces the friction-based mechanical braking component with an electromagnetic braking mechanism using permanent magnets. Since the braking force is generated through eddy currents induced in the rail by the magnetic field rather than through friction between brake shoes and rail, the braking performance remains stable and consistent regardless of weather conditions such as rain or snow.
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 solution provides a lightweight, efficiently controlled braking system that maintains braking force consistency across varying conditions without rail damage, reducing the overall weight of the rail brake and minimizing magnetic leakage.
Implementation Method 1
eddy currents C shown in Figure 8(c) are generated in the rail 5 due to the relative speed of the bogie frame and the rail 5
Implementation Method 2
A braking force which acts on the bogie frame is produced by the electromagnetic attraction force which is generated between the rail 5 and the cores of the electromagnets 4a
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(d)
Figure 3~4
AI summary
A lightweight eddy current rail brake 11 to be mounted on a bogie frame of a railway car comprises a magnet unit 12 which generates an electromagnetic attraction force with respect to a rail 5 and which comprises an elongated support member 15 and a plurality of permanent magnets 17. The support member 15 is ferromagnetic and extends generally parallel to the direction in which a side beam of a bogie frame extends, and it is rotatable about a shaft which is generally parallel to this direction. A plurality of permanent magnets 17 are arranged on the support member 15 in series and are spaced above a rail 5. At least two adjoining permanent magnets 17 of the plurality of permanent magnets 17 are arranged so as to have different polarities from each other.