Stator Three-Layer Oil Cooling for High-Power-Density Motors
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Solution Overview
Problem
Conventional stator cooling structures in electric vehicle motors face challenges in achieving high heat dissipation capabilities to cope with increasing power density, leading to insufficient cooling and complex manufacturing processes.
Innovation Solution
A stator design with three-layer cooling channels, including a first channel between the yoke part and housing, a second channel between tooth parts, and a third channel at the stator slot opening, facilitated by a flow guiding assembly, to enhance coolant oil flow and contact area for improved heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single-layer cooling channel is disposed at the root of stator teeth, then the cooling structure is simple, but the cooling capability is insufficient to meet high power density requirements
Solution Approach 1:
The cooling structure is segmented into three distinct cooling channels: a first cooling channel at the outer edge of the yoke part, a second cooling channel at the root of stator teeth, and a third cooling channel at the slot opening. This segmentation allows each channel to independently cool different regions, significantly improving overall heat dissipation capability while maintaining reasonable structural complexity through modular design
Solution Approach 2:
The cooling structure transitions from a single-layer planar design to a multi-layer spatial configuration. The three cooling channels are arranged at different radial positions and depths within the stator, creating a three-dimensional cooling network that increases the contact area between coolant and stator surfaces, thereby enhancing heat dissipation efficiency
2Temperature
If a cooling pipe is inserted into the stator, then two layers of cooling channels are achieved, but the structure becomes complex resulting in complex manufacturing process and high costs
Solution Approach 1:
The flow guiding assembly integrates multiple functions into a single component: it serves as a structural support, a flow distributor for the coolant, and a connector between the three cooling channels. By merging these functions, the design eliminates the need for separate cooling pipes and multiple assembly steps, simplifying the manufacturing process while achieving effective multi-layer cooling
Solution Approach 2:
The flow guiding assembly is designed to automatically distribute coolant flow to the three cooling channels based on pressure gradients and flow paths, without requiring external control mechanisms or complex valve systems. This self-regulating flow distribution simplifies the manufacturing process and reduces costs while maintaining effective cooling across all channels
3Temperature
If an oil passage is disposed in the middle of the stator tooth, then cooling is provided, but electromagnetic performance of the stator is affected
Solution Approach 1:
The cooling channels are strategically positioned in regions that do not interfere with the electromagnetic active zones. The first cooling channel is located at the outer edge of the yoke part, the second at the root of teeth between adjacent teeth, and the third at the slot opening. This local placement ensures that cooling functionality is provided without compromising the magnetic flux paths and electromagnetic performance
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 three-layer cooling design effectively increases the contact area between coolant oil and the stator, enhancing heat dissipation capabilities to meet cooling requirements in both low-speed high-torque and high-rotation-speed conditions, while maintaining electromagnetic performance.
Implementation Method 1
a first cooling channel is disposed between a radially outer edge of the yoke part and the housing. The first cooling channel may cool an outer surface of the iron core punching sheet. In addition, a second cooling channel is disposed on a radially inner edge of the yoke part, and the second cooling channel is located between adjacent tooth parts
Implementation Method 2
The three-layer oil-injection cooling design can increase a contact area between the coolant oil and the stator, to improve a heat dissipation capability of the stator
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A stator, a motor, and an electric vehicle are provided. The stator includes: a housing, where the housing has an accommodation space, and an oil inlet that communicates with the accommodation space is disposed on the housing; a ring-shaped iron core punching sheet, where the iron core punching sheet is disposed in the accommodation space, and abuts against an inner wall of the housing, the iron core punching sheet includes a yoke part and a plurality of tooth parts, the plurality of tooth parts are evenly distributed on an inner side of the yoke part in a circumferential direction, a stator slot is disposed between adjacent tooth parts, a first cooling channel is disposed between an outer edge of the yoke part and the housing, and a second cooling channel located between adjacent tooth parts is disposed on an inner edge of the yoke part; a spacer sleeve, where the spacer sleeve is sleeved in the iron core punching sheet, an outer surface of the spacer sleeve abuts against a side that is of the tooth part and that faces away from the yoke part, and a slot opening of the stator slot fits with the spacer sleeve to form a third cooling channel; and a flow guiding assembly, where the flow guiding assembly is disposed in the accommodation space, and is configured to guide, in a direction from the first cooling channel to the second cooling channel and then to the third cooling channel, coolant oil flowing out of the oil inlet. The three-layer oil-injection cooling design can improve a heat dissipation capability of the stator.