Eddy Current Torque Transmission for Sealed Submerged Motors
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Solution Overview
Problem
Existing generators and motors face challenges in preventing fluid leakage into their chassis, especially when used in submerged environments, where ferrous particles can damage internal components and require frequent maintenance to maintain sealing integrity.
Innovation Solution
An electric apparatus comprising a stator and two rotors, where the second rotor is made of conductive material and positioned adjacent to the first rotor, generating eddy currents due to rotational speed differences, allowing torque transmission without mechanical contact and thus preventing fluid leakage by maintaining the stator and first rotor in a sealed enclosure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing dispositive is positioned around the shaft to prevent fluid leakage, then fluid intrusion is prevented, but the sealing dispositive wears out over time requiring maintenance
Solution Approach 1:
The invention extracts the shaft from the system by using magnetic coupling between two rotors. The first rotor is sealed within the chassis while the second rotor remains external, eliminating the need for a shaft penetrating the chassis and the associated sealing dispositive that requires maintenance.
Solution Approach 2:
The invention replaces the mechanical shaft connection with a magnetic field-based torque transmission system. Torque is transmitted through eddy currents induced in the second rotor by the rotating magnetic field of the first rotor, eliminating mechanical contact and the need for seals at the chassis boundary.
2Productivity
If the shaft is directly coupled with the turbine to transmit mechanical power, then power transmission efficiency is improved, but the shaft rotation wears out the sealing dispositive allowing fluid leakage
Solution Approach 1:
The invention introduces a magnetic field as an intermediary between the first rotor (sealed) and the second rotor (external). This magnetic coupling allows torque transmission without direct mechanical connection, preventing wear of the sealing dispositive while maintaining efficient power transmission from the turbine to the generator.
Solution Approach 2:
The direct mechanical coupling between shaft and turbine is replaced with magnetic coupling. The first rotor rotates with the turbine, generating a rotating magnetic field that induces eddy currents in the second rotor, which then rotates to drive the generator. This substitution eliminates mechanical wear at the seal interface.
3Adaptability or versatility
If ferrous particles are present in the fluid, then magnetic attraction causes particles to accumulate on internal walls, but this damages the motor/generator components
Solution Approach 1:
The invention extracts the vulnerable internal components (stator and first rotor) from the fluid environment by sealing them within the chassis. Only the external second rotor contacts the fluid, preventing ferrous particles in the fluid from reaching and damaging the sensitive internal components through the sealed boundary.
Solution Approach 2:
The invention uses a sealed chassis enclosure as a protective barrier between the fluid environment containing ferrous particles and the internal motor/generator components. This sealing prevents particle intrusion while allowing the system to operate in submerged or fluid-filled environments.
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 solution effectively transmits torque between rotors without mechanical contact, reducing maintenance needs and preventing fluid intrusion, making it suitable for submerged applications like hydrokinetic turbines by using eddy currents to synchronize rotor speeds and generate electricity.
Implementation Method 1
A rotational speed difference between the first and second rotors generates eddy currents in the second rotor so that a torque is transmitted between the first and second rotors
Implementation Method 2
Rotation of the turbine creates a rotational speed difference between the first and second rotors. This rotational speed difference generates eddy currents in the second rotor, creating a torque transmitted from the second rotor to the first rotor
Implementation Method 3
Upon rotation of the rotor, a magnetic field of its permanent magnets energizes the coils of the stator to produce current by electromagnetic induction
Data Source
AI summary
An electric apparatus comprises a stator having an array of coils positioned within its periphery and a first rotor having an array of magnet pairs positioned within its periphery. The first rotor has one face adjacent to the stator. A second rotor made of conductive material is positioned adjacent to another face of the first rotor. A coupling mechanism may be connected to the second rotor. The electric apparatus may be connected to an electric power source and act as a motor for driving a mechanical load attached to the coupling mechanism. The electric apparatus may alternatively be connected to an electric load, a turbine being attached to the coupling mechanism for generating electric power. An enclosure may protect components of the electric apparatus against external elements, for example to allow underwater operation.