Rotary Electric Machine Stator Cooling via Offset Laminations
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Solution Overview
Problem
Rotating electrical machines without a casing face challenges in cooling efficiency and safety due to sharp edges from fin cutting, while machines with a carcass are costly and create thermal barriers.
Innovation Solution
The use of overlapping, angularly offset sheets with closed channels within the stator laminations creates flow disturbances, enhancing heat exchange and eliminating sharp edges, allowing for improved cooling without a carcass, and optionally using a casing for further cooling and customization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a machine is designed without a casing to reduce cost and improve heat dissipation, then manufacturing cost decreases and thermal barrier is reduced, but sharp edges from fin cutting create safety hazards
Solution Approach 1:
The invention converts the harmful sharp edges created by fin cutting into a beneficial feature by using the cut edges to form closed cooling channels. The channels are defined by the fin structures themselves, where the cut edges are folded back or bent to create channel walls that are rounded and safe to touch, while still providing effective cooling pathways.
Solution Approach 2:
The invention uses thin metal sheets that are folded and bent to form the cooling channels. The flexibility of the thin sheets allows the sharp cut edges to be transformed into rounded, safe surfaces through folding and bending operations, while maintaining the structural integrity of the cooling channels.
2Ease of manufacture
If straight cooling channels are used in a casingless machine, then manufacturing is simplified, but cooling efficiency is reduced due to lack of turbulence
Solution Approach 1:
The invention introduces curvature and non-linear paths into the cooling channels by using alternating fin arrangements and angled folds. The channels follow curved trajectories rather than straight lines, creating turbulence in the coolant flow and improving heat exchange efficiency while maintaining manufacturability through standard sheet metal forming operations.
Solution Approach 2:
The invention creates dynamic flow conditions within the channels by designing alternating fin patterns and angled channel sections that induce turbulence. The channel geometry varies along its length, with changes in direction and cross-section that actively promote mixing and enhance convective heat transfer, transforming static straight channels into dynamic flow paths.
3Temperature
If fins are cut on the outside of the lamination package to create cooling channels, then cooling is improved, but sharp edges are created that pose safety risks
Solution Approach 1:
The invention converts the harmful sharp edges created by fin cutting into a beneficial feature by using the cut edges to form closed cooling channels. The channels are defined by the fin structures themselves, where the cut edges are folded back or bent to create channel walls that are rounded and safe to touch, while still providing effective cooling pathways.
Solution Approach 2:
The invention extracts the harmful sharp edges from the external surface by folding them inward to form the walls of closed cooling channels. The dangerous cut edges are removed from the exterior by bending them into the internal channel structure, eliminating the safety hazard while preserving the cooling function.
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 design improves cooling efficiency and safety by increasing turbulence within the channels, reducing the need for external carcass cooling and eliminating sharp edges, while allowing for customizable casings and various channel shapes.
Implementation Method 1
the disturbance of the flow within the channels at the transition between the sub-packages makes it possible to increase the heat exchange between the pack of sheets and the cooling fluid compared to a straight passage which only induces little turbulence
Data Source
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AI summary
The invention relates to an electric machine comprising a stator, said stator comprising a packet (10) of magnetic sheets made up of at least one first sub-packet (50) and at least one second sub-packet (60) adjacent to the first sub-packet, the sheets of the first and second sub-packets having overlapping portions, which each comprise at least one closed channel formed within the sheets, the sheets being identical but angularly offset relative to one another by an angle 360°/n about the axis of the machine, where n is an integer other than zero, the sheets being asymmetrical by a rotation of 360°/n so that the portions of the sheets thus offset that overlap are not identical and create said disruption of the flow at the transition between the channels of the first and second sub-packets.