Rotor Shaft Cooling Path for Electric Machine Heat Management
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Solution Overview
Problem
Rotating electric machines experience reduced rotation efficiency due to excessive heat generation and rotary reaction forces caused by cooling mediums, leading to demagnetization and inefficiency, particularly in designs with axial oil paths and leakage issues.
Innovation Solution
A rotor design with a cylindrical rotor core and shaft featuring a cooling medium flow space within the rotor shaft, where the cooling medium is supplied and discharged through strategically positioned openings to minimize rotary reaction forces and leakage, allowing for efficient cooling of the permanent magnet without the need for additional leakage prevention structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling medium flows through core axial oil path, then permanent magnet is cooled, but cooling medium leaks into gap between rotor and stator causing drag and rotation loss
Solution Approach 1:
The invention extracts the cooling medium flow path from the core axial oil path and relocates it to the rotor shaft axial oil path. The cooling medium is supplied to the rotor shaft axial oil path and flows along the circumferential face of the rotor shaft, then discharged to cool the coil ends, completely separating the cooling medium flow from the core area to prevent leakage into the gap between rotor and stator.
Solution Approach 2:
The rotor shaft axial oil path serves as an intermediary structure that enables cooling of the permanent magnet and coil without requiring the cooling medium to flow through the core axial oil path. The cooling medium flows through this intermediary path and is discharged to cool the coil ends, preventing direct contact with the gap between rotor and stator.
2Temperature
If cooling medium is supplied to rotor shaft axial oil path, then cooling effect is achieved, but rotary reaction force from cooling medium reduces rotor rotation efficiency
Solution Approach 1:
Instead of having the cooling medium flow radially outward from the center (which creates significant rotary reaction force), the invention inverts the flow direction by supplying the cooling medium to the rotor shaft axial oil path and allowing it to flow along the circumferential face toward the discharge hole. This inverted flow path reduces the rotary reaction force and improves rotation efficiency.
Solution Approach 2:
The invention changes the cooling medium flow from a radial direction (creating high rotary reaction force) to an axial direction along the rotor shaft (creating minimal rotary reaction force). The cooling medium flows in the axial dimension rather than the radial dimension, significantly reducing the harmful rotary reaction force while maintaining cooling effectiveness.
3Reliability
If additional structures are added to prevent cooling medium leakage, then leakage is prevented, but manufacturing cost and complexity increase
Solution Approach 1:
The invention extracts the cooling medium flow path from the core area and relocates it to the rotor shaft axial oil path. This extraction eliminates the need for additional leakage prevention structures such as seals or barriers in the core area, as the cooling medium now flows through a separate path that naturally prevents leakage into the gap between rotor and stator.
Solution Approach 2:
The rotor shaft axial oil path serves multiple functions: it supplies cooling medium to cool the permanent magnet, provides a discharge path for the cooling medium to cool the coil ends, and prevents leakage into the gap between rotor and stator. This multi-functional design eliminates the need for additional leakage prevention structures, reducing both complexity and manufacturing cost.
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 rotation efficiency by reducing kinetic energy consumption and maintaining effective cooling of the rotor core and permanent magnet, while lowering manufacturing costs and preventing coolant leakage.
Implementation Method 1
The cooling medium is supplied to the rotor shaft axial oil path, and the cooling medium flows along the circumferential face of the rotor shaft axial oil path due to the centrifugal force generated by the rotation of the rotor shaft
Implementation Method 2
An inner circumferential face of the rotor core is in heat-transferable contact with the rotor shaft
Data Source
AI summary
In a rotor for the dynamo, the interior circumference face of a rotor core main body makes contact in a thermally transmissible manner with a rotor axle, and the rotor axle includes a cooling medium circulation space. The rotor is provided with a cooling medium supply member, which supplies the cooling medium to the cooling medium circulation space. The cooling medium supply member is provided with a cooling medium supply path that extends in the rotor axle direction, and cooling medium supply holes that extend externally in the direction of the rotor diameter. The cooling medium supply holes are provided with supply apertures that open toward the cooling interior circumference face. The rotor axle is provided with cooling medium discharge holes that extend externally in the direction of the rotor diameter. The cooling medium discharge holes are provided with discharge apertures that open externally in the diameter direction.