Rotating Electric Machine Cooling Oil Channel Design
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Solution Overview
Problem
Conventional rotary electric machines face issues with temperature control and size due to inadequate cooling oil distribution, leading to increased thermal ratings and pumping power requirements, which result in larger machine sizes.
Innovation Solution
The design features an annular cooling oil channel with an open surface facing the coils and oil flow direction changing projections that convert axial flow into radial flow, ensuring uniform cooling oil distribution between coils, reducing pressure loss and pumping power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling oil spraying portions are disposed on the vertically upper portions of the coil ends, then the cooling oil can be supplied to the upper portions of the coils, but the temperature of the vertically lower portions of the coil ends increases due to inadequate cooling
Solution Approach 1:
The invention changes the cooling oil flow direction from vertical (single dimension) to axial direction (another dimension) by using oil flow direction changing projections. This allows cooling oil to be supplied uniformly to all portions of the coils including the previously under-cooled lower portions, improving overall temperature control and thermal rating.
2Loss of energy
If the openings of the circumferential oil channels are covered by the oil channel covers, then the oil channels are protected, but the pressure loss in the oil channels is increased requiring increased pumping power
Solution Approach 1:
The invention extracts the oil channel cover that causes pressure loss and removes it entirely. By making the cooling oil channel surface an opening without a cover, the invention eliminates the source of pressure loss while still achieving effective cooling, thereby reducing the pumping power requirement.
3Loss of energy
If the nozzles are separated from the coils, then the nozzle positioning is simplified, but large pumping power is required to provide sufficient spraying pressure
Solution Approach 1:
The invention merges the nozzle function with the cooling oil channel by making the channel surface an opening that directly faces the coils. This integration eliminates the need for separate nozzles and reduces the distance between the cooling oil source and the coils, thereby reducing pressure loss and pumping power requirements.
4Loss of energy
If the cooling oil channel surface facing the coils is made into an opening, then the pressure loss is reduced and pumping power is minimized, but the cooling oil flow direction control becomes more challenging
Solution Approach 1:
The invention segments the cooling oil channel surface into multiple opening portions that face different coil regions. By dividing the opening into specific segments positioned at different locations, the invention achieves both pressure loss reduction and effective flow direction control to different coil areas.
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 configuration reduces the size of the rotary electric machine by minimizing pressure loss and pumping power, while effectively cooling the coils and improving thermal ratings.
Implementation Method 1
a plurality of oil flow direction changing projections that are respectively disposed inside the cooling oil channel and are arranged circumferentially so as to face gaps between coils among the plurality of coils and such that cooling oil receiving surfaces face upstream in a direction of flow of the cooling oil so as to change the cooling oil that flows through the cooling oil channel to an axial flow so as to be supplied to the gaps between the coils
Implementation Method 2
a nozzle that sprays cooling oil that is conveyed under pressure from the oil pump into the cooling oil channel from above
Implementation Method 3
cooling oil that is sprayed from the first and second cooling oil spraying portions and is supplied to the upper portion of each of the first and second coil ends
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention provides a rotary electric machine that reduces pressure loss and minimizes pumping power by making a surface of a cooling oil channel that faces a coil into an opening, and that also suppresses temperature increases in the coil and enables reductions in size to be achieved by changing cooling oil that flows through the cooling oil channel into an axial flow so as to be supplied between the coils using oil flow direction changing projections. The rotary electric machine according to the present invention includes: an annular cooling oil channel that is configured inside an externally mounted frame so as to face axially toward a plurality of coils that are arranged in an annular shape and such that a surface that faces the plurality of coils is made into an opening; an oil pump; a nozzle that sprays cooling oil that is conveyed under pressure from the oil pump into the cooling oil channel from above; and a plurality of oil flow direction changing projections that are respectively disposed inside the cooling oil channel and are arranged circumferentially so as to face gaps between the coils and such that cooling oil receiving surfaces face upstream in a direction of flow of the cooling oil so as to change the cooling oil that flows through the cooling oil channel to an axial flow so as to be supplied to the gaps between the coils.