Axial Magnetic Coupling With Thermal Isolation for Hermetic Pumps
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Solution Overview
Problem
Existing magnetic couplings for hermetic pumps face challenges such as high cost, complex assembly, increased permeation rates, and inadequate thermal management, particularly in axial configurations, which can lead to excessive heating and reduced magnetic field strength.
Innovation Solution
An axial magnetic coupling assembly with a labyrinth seal and asymmetrical magnets, featuring a sealing gap to limit gas conductance and thermal isolation, along with balancing magnets to counteract axial forces, is implemented to address these issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hermetic barrier material is placed in the air gap of a magnetic coupling, then hermeticity is improved, but excessive power loss and heat build-up occur due to eddy currents in conductive materials
Solution Approach 1:
A non-conductive hermetic barrier material is introduced as an intermediary between the drive and driven magnets in the air gap. This mediator maintains hermetic separation while preventing eddy current formation, thus blocking the harmful energy loss pathway without compromising the magnetic coupling function.
Solution Approach 2:
The electrical conductivity parameter of the hermetic barrier material is changed from conductive to non-conductive. This parameter change eliminates eddy current losses while maintaining the hermetic sealing function, resolving the contradiction between hermeticity and energy loss.
2Loss of energy
If a non-conductive hermetic barrier material is used in the air gap, then power loss is reduced, but permeation resistance may be compromised
Solution Approach 1:
A composite hermetic barrier material is used that combines non-conductive properties (to prevent eddy currents) with low permeation characteristics (to maintain hermeticity). The composite structure integrates multiple material properties to simultaneously address both requirements that would be conflicting in single-material solutions.
3Temperature
If thermal isolation is implemented for the magnetic coupling, then operational temperature is reduced, but device complexity increases
Solution Approach 1:
The magnetic coupling assembly provides its own thermal isolation through the non-conductive hermetic barrier material already present in the air gap. This existing component serves dual functions: maintaining hermeticity and providing thermal isolation. No additional dedicated thermal management components are required, as the system uses its inherent structure to manage heat.
4Volume of moving object
If axial magnetic coupling configuration is used, then space efficiency is improved, but excessive heating occurs
Solution Approach 1:
The non-conductive hermetic barrier material acts as a thermal mediator in the axial magnetic coupling configuration. It maintains the compact axial design while introducing thermal resistance that prevents excessive heat transfer, thus mediating between the space efficiency requirement and thermal management need.
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 cost-effective, thermally isolated, and structurally stable magnetic coupling with reduced axial forces, enhancing the operational efficiency and longevity of hermetic pumps.
Implementation Method 1
the sealing gap has a size effective to limit gas conductance therethrough and thereby thermally isolate the chamber from a region external to the sealing gap and the chamber
Implementation Method 2
A magnetic coupling includes one or more drive magnets and one or more driven magnets separated by an air gap, thereby establishing magnetic fields in the air gap between the drive magnet(s) and driven magnet(s). The associated magnetic forces are utilized in a known manner to transfer the torque from the drive shaft to the driven shaft
Data Source
AI summary
A magnetic coupling assembly includes a thermal isolation system that isolates the assembly from a heat source such as a pump coupled to a driven side of the assembly, thereby enabling the assembly to operate at a reduced temperature. The system may include a labyrinth seal that reduces convective heat transfer to the assembly. The seal may include a sealing gap defined between a rotating component and a stationary component. The gap is sized to limit gas conductance therethrough. The system may also include one or more spacers positioned to reduce or eliminate conductive heat transfer from one component to another. The assembly may be utilized in a pump for contactless coupling of a motor shaft to a pump shaft.