Stator Coil Axial Overlap for Liquid Coolant Flow
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Solution Overview
Problem
Existing rotating electric machines for motor vehicles face efficiency issues due to heat generation in stator coils, leading to potential insulation failure if liquid coolant does not effectively flow through the coil end parts, causing excessive temperature increases.
Innovation Solution
The design incorporates axially-overlapping pairs of long-pitch and short-pitch turn portions in the stator coil, with the short-pitch turn portions located inside the long-pitch turn portions, creating a void space for coolant flow, and features rounded corners and arc-shaped surfaces to enhance coolant flow and surface tension, ensuring effective cooling across the entire circumferential range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid coolant is supplied to cool the stator coil, then temperature control is improved, but cooling effectiveness deteriorates when coolant cannot flow through coil end parts
Solution Approach 1:
The coil end part is segmented into multiple turn portions (first through fourth turn portions) arranged in different axial layers. This segmentation creates multiple flow paths for the coolant, ensuring that cooling effectiveness is maintained even if some paths are blocked. Each turn portion can be cooled independently, preventing hot spots and ensuring reliable temperature control throughout the coil end part.
Solution Approach 2:
The invention extends the cooling structure into the axial dimension by arranging turn portions in multiple axial layers. The coolant flows through void spaces between these axially-stacked turn portions, creating a three-dimensional cooling network. This dimensional extension ensures comprehensive cooling coverage of the coil end part, addressing the limitation of conventional two-dimensional cooling approaches.
2Reliability
If turn portions are arranged to create void spaces for coolant flow, then cooling effectiveness is improved, but structural complexity increases
Solution Approach 1:
Multiple turn portions (first through fourth turn portions) are merged into a single integrated coil structure where the turn portions are electrically connected in series. This merging approach creates void spaces for coolant flow while maintaining a unified electromagnetic structure, avoiding the need for separate cooling components and reducing overall system complexity.
Solution Approach 2:
The turn portions serve dual functions: they provide the necessary electrical winding structure for electromagnetic operation and simultaneously create void spaces that enable coolant flow. This multi-functionality eliminates the need for separate cooling channels, reducing structural complexity while maintaining effective cooling.
3Ease of operation
If axially-overlapping pairs of turn portions are created, then coolant flow distribution is improved, but manufacturing complexity increases
Solution Approach 1:
The turn portions are pre-formed with specific geometries and insulating coat configurations during the coil manufacturing process. The insulating coats are applied in advance to the turn portions, and the axially-overlapping arrangement is built into the coil structure before installation. This preliminary preparation simplifies the overall manufacturing process by avoiding complex post-assembly operations.
Solution Approach 2:
The invention varies the axial positions and geometrical parameters of different turn portions to create the axially-overlapping configuration. By controlling parameters such as turn portion length, axial position, and radial dimensions, the design achieves optimal coolant flow distribution while maintaining manufacturability through standardized winding processes.
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 allows for effective cooling of the stator coil, preventing insulation failure and maintaining efficiency by ensuring consistent coolant flow through the void spaces between overlapping turn portions, thereby managing heat effectively.
Implementation Method 1
liquid coolant dropped on the coil end part, thereby cooling the stator coil
Implementation Method 2
liquid coolant dropped on the coil end part flows through the void space
Implementation Method 3
features rounded corners and arc-shaped surfaces to enhance coolant flow and surface tension
Data Source
AI summary
In a rotating electric machine, a stator includes a stator core having slots formed therein and a stator coil comprised of phase windings each of which includes in-slot portions and turn portions. The turn portions of the phase windings together constitute a coil end part of the stator coil. Further, a cooling mechanism is provided to drop liquid coolant onto the coil end part. Moreover, the turn portions of the phase windings include long-pitch turn portions and short-pitch turn portions. In the coil end part, there are axially-overlapping pairs of the long-pitch and short-pitch turn portions over an entire circumferential range of the stator coil. For each axially-overlapping pair of the long-pitch and short-pitch turn portions, the short-pitch turn portion is located axially inside the long-pitch turn portion and faces the long-pitch turn portion through a void space formed therebetween over entire lengths of the long-pitch and short-pitch turn portions.