Rotating Electric Machine Inclined Discharge Grooves
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Solution Overview
Problem
In rotating electric machines where coolant is supplied to the gap between the stator and rotor for cooling, the coolant tends to remain in the small clearance, increasing drag friction and loss during rotor rotation.
Innovation Solution
The design incorporates inclined discharge grooves on the stator teeth, which direct the coolant radially outward from the coolant supply position, preventing it from remaining in the gap and enhancing cooling efficiency while minimizing drag loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If coolant is supplied to the gap between stator and rotor for cooling, then cooling efficiency is improved, but drag friction increases due to coolant remaining in the gap
Solution Approach 1:
The gap between stator and rotor is segmented into multiple regions by inclined discharge grooves on stator teeth. These grooves divide the coolant flow path into multiple discharge channels, preventing coolant accumulation and reducing drag friction while maintaining effective cooling across different zones of the gap.
Solution Approach 2:
The discharge grooves are inclined at an angle relative to the radial direction, introducing a circumferential component to the coolant discharge direction. This angular discharge pattern utilizes the rotational motion of the rotor to甩 out coolant more effectively from the gap, preventing stagnation and reducing drag loss.
2Temperature
If coolant is ejected toward the distal end face of teeth, then coolant reaches the gap for cooling, but coolant may stagnate in the small clearance
Solution Approach 1:
The discharge grooves are designed with asymmetric inclination angles relative to the radial direction. This asymmetric geometry creates non-uniform coolant flow distribution that leverages the rotational speed variation across the gap, promoting continuous coolant movement and preventing stagnation in the clearance zone.
Solution Approach 2:
The inclined discharge grooves utilize the dynamic rotational motion of the rotor to generate centrifugal forces that actively甩 out coolant from the gap. The coolant flow is transformed from a static accumulation problem to a dynamic discharge process, where rotational speed enhances coolant ejection and prevents stagnation.
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 solution effectively reduces coolant retention in the gap, improving cooling efficiency and minimizing drag loss during rotor rotation, with the grooves' design minimizing performance deterioration.
Implementation Method 1
The discharge groove is inclined radially outwardly of the stator, from a coolant supply position that is an axial position of the stator facing the coolant outlet, toward one edge of the distal end face of the corresponding tooth
Data Source
AI summary
A rotating electric machine includes a stator, a rotor, and a coolant supply passage. Coils are wound on the teeth of the stator. The rotor is disposed coaxially with the stator, and has an outer circumferential surface that faces respective distal end faces of the teeth with a constant gap formed therebetween. The coolant supply passage is disposed inside the rotor, and is configured to eject a coolant from a coolant outlet of the outer circumferential surface of the rotor toward the distal end face of a corresponding one of the teeth so as to supply the coolant to the gap. A discharge groove is formed in the distal end face of the corresponding tooth. The discharge groove is inclined radially outwardly of the stator, from a coolant supply position as an axial position of the stator facing the coolant outlet, toward one edge of the distal end face of the corresponding tooth.