Symmetric Can Sealing for Thin-Walled Electric Rotating Machines
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Solution Overview
Problem
Existing electric rotating machines face challenges in achieving high power density due to issues with heat dissipation and polymer insulation failure in stator windings, particularly under liquid cooling conditions.
Innovation Solution
A seal design for the can of an electric rotating machine that minimizes stress on thin-walled cans by using symmetrically arranged sealing elements on both sides of the can, balancing forces and reducing internal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the wall thickness of the can is reduced to minimize magnetic losses, then the magnetic properties of the electric rotating machine are improved, but the can becomes more susceptible to deformation under external pressure from the liquid cooling system
Solution Approach 1:
The can is segmented into multiple circumferential sections that can deform independently under pressure. This segmentation allows the can to accommodate pressure loads without excessive deformation, maintaining dimensional stability while keeping wall thickness minimal to reduce magnetic losses.
Solution Approach 2:
The can is constructed using composite materials that provide high strength-to-weight ratio and pressure resistance. The composite structure enables the can to withstand external pressure from the liquid cooling system with reduced wall thickness, thereby minimizing magnetic losses while maintaining structural integrity.
2Strength
If the wall thickness of the can is increased to improve dimensional stability and buckling resistance, then the structural strength is improved, but the magnetic losses increase
Solution Approach 1:
The can is divided into multiple circumferential segments that can deflect independently under pressure. This segmentation provides buckling resistance without requiring increased wall thickness, thus maintaining low magnetic losses while improving structural stability.
Solution Approach 2:
The can features a curved or spherical cross-sectional shape instead of a flat design. This curvature provides inherent buckling resistance and distributes pressure evenly, allowing for thinner walls that reduce magnetic losses while maintaining high buckling stability.
3Device complexity
If sealing elements are placed only on one side of the can, then the sealing structure is simpler, but the can experiences uneven stress distribution and deformation
Solution Approach 1:
The sealing structure uses asymmetric placement of sealing elements that are compensated by corresponding structural features on the opposite side. This asymmetric design with compensation achieves uniform stress distribution without requiring symmetric sealing elements on both sides, maintaining simplicity while improving stress uniformity.
Solution Approach 2:
The can includes counterbalancing structural features that compensate for the asymmetric placement of sealing elements. These counterweight features distribute the stress evenly across the can structure, preventing deformation despite the simpler one-sided sealing configuration.
4Power
If the can is designed with minimal wall thickness to reduce magnetic losses, then the power density and compactness are improved, but the can becomes more vulnerable to pressure-induced deformation and failure
Solution Approach 1:
The can is segmented into multiple circumferential sections that can deform independently under pressure. This segmentation allows the thin-walled can to accommodate pressure loads without catastrophic failure, maintaining high power density through minimal wall thickness while improving reliability under pressure.
Solution Approach 2:
The can employs a curved cross-sectional shape that provides inherent pressure resistance. This geometric feature allows the can to withstand liquid cooling system pressures with minimal wall thickness, achieving high power density without compromising reliability.
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 proposed seal design effectively reduces stress on the can, allowing for thinner wall thicknesses and improved sealing reliability, which enhances the thermal service life and power density of electric rotating machines.
Implementation Method 1
a cooling liquid, in particular an oil with good cooling properties, circulates on the inside of the coil
Implementation Method 2
the forces acting at the axial end of the can (1) due to the seal are equalized
Data Source
AI summary
Various embodiments of the teachings herein include an electric rotating machine or liquid pump. An example includes: a first liquid-free area; a second liquid-containing area; a can separating the first area from the second area, the can defining a stator-side and a rotor-side; and a sealing element at an axial end of the can. The sealing element is arranged symmetrically with respect to force effect on the can so that forces acting at the axial end of the can due to the seal are equalized.