Corrugated Fin Heat Transfer Structure for Electric Motor Rotor Cooling
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Solution Overview
Problem
Conventional cooling systems for high power electric motors, particularly those with compact designs, often fail to effectively manage high heat densities in rotors due to limited space for cooling air flow between the stator and rotor.
Innovation Solution
A heat transfer assembly featuring a corrugated fin sheet attached to the interior of the motor rotor shaft, which increases the surface area for convective cooling by forming a plurality of radially extending loops, enhancing both conductive and convective heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling schemes pass cooling fluid between the stator and rotor, then cooling is provided for the motor, but the cooling effectiveness is inadequate for high power motors due to high rotor heat density and limited available area
Solution Approach 1:
The patent transitions from a two-dimensional cooling surface (flat rotor interior) to a three-dimensional cooling structure by adding corrugated fins that extend radially outward. This dimensional transformation creates multiple cooling surfaces (fin surfaces) within the limited radial space, effectively increasing the heat transfer area without occupying additional axial or radial envelope space.
Solution Approach 2:
The patent divides the continuous rotor interior surface into multiple segmented cooling surfaces by adding corrugated fins. These fins create a series of radial extensions that segment the cooling path and provide multiple discrete heat transfer surfaces, allowing cooling fluid to access different portions of the rotor structure independently and efficiently.
2Volume of moving object
If the size of high power motors decreases to achieve compact design, then motor size is reduced, but the available area for passing cooling air between the stator and rotor also decreases
Solution Approach 1:
The corrugated fin structure utilizes the radial dimension to create extended cooling surfaces. By folding the fin material radially outward and back, the structure creates a three-dimensional heat transfer surface that occupies minimal axial space while providing maximum cooling area, enabling effective cooling in compact motor designs.
Solution Approach 2:
The corrugated fin structure is nested within the rotor interior space, with fins folding back on themselves to create a compact, space-efficient configuration. This nested arrangement allows the cooling structure to be contained within the existing motor envelope without requiring additional external space.
3Area of stationary object
If a corrugated fin heat transfer structure is added to the rotor shaft, then heat transfer surface area is increased, but device complexity increases
Solution Approach 1:
The patent employs thin corrugated fin sheets that are flexible enough to be inserted and expanded within the rotor interior. These thin film structures provide large surface area while minimizing material usage and structural complexity, as the fins can be made from thin-walled tubular sections or sheet metal that is easily formed and installed.
Solution Approach 2:
The patent replaces complex mechanical mounting systems with a simple expansion-based installation method. The corrugated fins are inserted in a compressed or folded state and then allowed to expand radially to their operational configuration, eliminating the need for complex fasteners, welds, or mechanical attachment systems.
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 significantly improves cooling efficiency, allowing for higher power densities, reduced motor size and weight, increased operational efficiency, and extended lifespan by effectively removing heat from the rotor.
Implementation Method 1
a corrugated fin heat transfer structure positioned within the shaft and configured to draw heat from the rotor assembly
Implementation Method 2
increases the surface area for convective cooling by forming a plurality of radially extending loops
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
An electric motor (12) comprises a housing, a stator assembly (28) mounted within the housing, a shaft (26A, 26B) extending axially through the stator assembly (28) and supported by the housing, and a rotor assembly (30) mounted to the shaft. A corrugated fin heat transfer structure (44) is positioned within the shaft (26A, 26B) and is configured to draw heat from the rotor assembly (30). The corrugated fin heat transfer structure (44) can comprise a sheet forming a plurality of radially extending loops (54), which may have radially outer crests (58) and radially inner troughs (54). The crests may be offset relative to the troughs.