Electric Machine Rotor Cooling via Segmented Stator Passages
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Solution Overview
Problem
Existing electric machine rotors with laminated cores and magnets face inefficiencies in heat removal due to long cooling paths through the laminated core and shaft, leading to reduced cooling performance, especially during dynamic operations.
Innovation Solution
Incorporating multiple coolant passages around the center of the borehole in each plate or partial laminated core, aligned with the staggering angle, to create a large number of axial cooling ducts that are closer to the heat source, allowing for efficient heat transfer and maintaining cooling performance during dynamic operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If coolant passages are arranged in the shaft for cooling the rotor, then cooling is provided, but the heat removal path is long from the exterior region through the laminated core and shaft-hub connection to the cooled inner surface
Solution Approach 1:
The invention divides the cooling system into multiple segments by providing multiple coolant passages distributed around the circumference of each plate or partial laminated core. This segmentation creates multiple parallel heat removal paths, reducing the effective heat removal distance from the outer circumference to the coolant passages, thereby improving cooling efficiency without requiring a longer shaft structure.
Solution Approach 2:
The invention transitions from a single-dimensional cooling path through the shaft hub to a multi-dimensional cooling architecture. By arranging coolant passages radially distributed around the borehole center in each plate, the cooling system accesses heat sources directly at multiple radial positions, creating short heat removal paths in the radial direction rather than relying on axial heat transfer through the shaft.
2Temperature
If multiple coolant passages are arranged around the center of the borehole in each plate, then a large cooled surface area is provided with short heat removal paths, but the plate design becomes more complex
Solution Approach 1:
The invention makes the coolant passage arrangement universal across all plates or partial laminated cores. The same pattern of multiple coolant passages distributed around the borehole center is replicated in every plate, allowing standardized manufacturing processes. This universality maintains cooling efficiency while simplifying production through standardization, offsetting the initial design complexity with manufacturing simplicity.
3Temperature
If the angle offset of coolant passages corresponds to the pivot angle of plates, then coolant passages align to form axial cooling ducts, but the manufacturing precision requirement increases
Solution Approach 1:
The invention incorporates the pivot angle offset into the preliminary design and manufacturing of the coolant passages. By pre-calculating and pre-positioning the coolant passages with the exact angle offset corresponding to the plate pivot angle, the alignment of cooling ducts is achieved automatically during assembly. This preliminary action eliminates the need for high-precision alignment during final assembly, as the offset is already built into the plate geometry.
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 enhances cooling efficiency by providing a large cooled surface area with short heat removal paths and maintains cooling performance even during acceleration, as the coolant passages are strategically positioned to align with the heat generation areas.
Implementation Method 1
the coolant passages are formed on the side of the plate or partial laminated core and are accordingly located significantly closer to the location of the lost energy introduction and thus the strong heating than would be the case with shaft cooling
Implementation Method 2
a correspondingly large number of cooling ducts or cavities extending axially through the rotor as such can be formed, so that because of the plurality of these individual ducts, a large cooled surface is provided in total inside the rotor
Data Source
AI summary
A rotor for an electric machine, having a laminated core, which is arranged on a shaft and provided with magnets. Multiple individual adjoining plates pushed onto a shaft or of partial laminated cores having multiple plates have a central borehole accommodating the shaft. At least a part of the plates or partial laminated cores are pushed onto the shaft pivoted by a predetermined pivot angle (α). Every plate or partial laminated core includes multiple coolant passages arranged distributed around the center (Z) of the borehole. The angle offset of two adjacent coolant passages corresponds to the pivot angle (α).