Oil-Cooled Rotor Laminations With Closed-Loop Shaft Channels
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current electric motor cooling systems, especially for high-power motors above 15 kW, face inefficiencies due to non-uniform cooling and increased weight from air cooling systems, and volume changes in phase change materials, while liquid cooling systems can be unbalanced and ineffective in transferring heat uniformly.
Innovation Solution
A closed-loop oil cooling system where oil is pumped through a hollow rotor shaft and directed to balance plates, which distribute it to channels within the lamination stack using centrifugal force, ensuring uniform heat transfer and reduced thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If air cooling system is used for high-power motor (15-20 kW or more), then motor can operate at high power output, but cooling efficiency becomes insufficient and temperature control deteriorates
Solution Approach 1:
The patent transitions from air cooling to liquid (oil) cooling by introducing a closed-loop coolant pathway with channels in the rotor shaft, balance plates, and lamination stack. The coolant circulates through these channels to efficiently remove heat from high-power motor components, solving the insufficient cooling efficiency problem while maintaining high power output capability.
2Reliability
If water cooling system or oil cooling system is used to prevent degradation and demagnetization, then motor reliability increases, but system complexity and weight increase
Solution Approach 1:
The patent integrates the cooling function directly into the motor structure by incorporating coolant channels within the rotor shaft, balance plates, and lamination stack themselves. This merging of cooling pathways with structural components eliminates the need for separate external cooling systems, thereby maintaining motor reliability while reducing overall system complexity.
Solution Approach 2:
The rotor shaft and balance plates serve dual functions: they provide mechanical structural support for motor operation and simultaneously act as coolant conduits for thermal management. This multi-functionality reduces the number of separate components needed, thereby reducing system complexity while maintaining reliable cooling for high-power operation.
3Reliability
If liquid cooling system is used to improve cooling efficiency, then heat transfer improves, but cooling uniformity deteriorates due to unbalanced cooling
Solution Approach 1:
The patent divides the cooling function into multiple segmented channels distributed throughout the rotor shaft, encoder-end balance plate, and output-end balance plate. These segmented coolant pathways are strategically positioned to distribute cooling uniformly across different regions of the motor, preventing hot spots and ensuring balanced temperature distribution while maintaining high cooling efficiency.
Solution Approach 2:
The patent implements location-specific cooling channels tailored to the thermal requirements of different motor components. The rotor shaft contains axial and radial channels positioned to cool specific high-heat-generation zones, while the balance plates have channels configured to address local thermal conditions at their respective ends, thereby achieving uniform overall cooling through localized optimization.
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 system provides effective and uniform cooling to electric motor laminations, maintaining temperature within specified limits without significant weight or cost increases, enhancing motor performance and reliability.
Implementation Method 1
cooling laminations of a rotor of an electric motor... uniform heat transfer and reduced thermal resistance
Implementation Method 2
directed to balance plates, which distribute it to channels within the lamination stack using centrifugal force
Data Source
AI summary
Various methods and systems are provided for a system for cooling an electric motor that includes a rotor shaft rotatably mounted inside a motor housing, a lamination stack integrally connected to the rotor shaft, an encoder-end balance plate integrally connected to a first end of the lamination stack and a first end of the rotor shaft, an output-end balance plate integrally connected to a second end of the lamination stack and a second end of the rotor shaft, an oil supply coupled to the output-end balance plate and the rotor shaft. A closed-looped coolant pathway is formed between the transmission, the rotor shaft, the encoder-end balance plate, the lamination stack, and the output-end balance plate.