Rotating Electric Machine Case Flow Path for Uniform Stator Cooling
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Solution Overview
Problem
Existing rotating electric machines experience uneven cooling effects due to temperature rise and variation of the refrigerant flowing through the flow path, leading to inconsistent cooling efficiency across the stator.
Innovation Solution
A rotating electric machine case with a flow path design that maintains a constant inner diameter and increases the outer diameter and wall thickness downstream, ensuring even cooling by managing the refrigerant's temperature gradient and heat capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the refrigerant flows through the flow path from upstream to downstream, then cooling effect is provided to the stator, but the refrigerant temperature rises causing uneven cooling
Solution Approach 1:
The patent applies local quality by making the wall thickness of the case variable along the flow path. Specifically, the wall thickness is smaller at the upstream side and larger at the downstream side of the flow path. This creates different thermal characteristics in different locations: the thinner upstream wall allows better heat transfer to cool the incoming refrigerant, while the thicker downstream wall compensates for the heated refrigerant by providing additional thermal mass and cooling capacity, thereby achieving uniform cooling throughout the stator despite the refrigerant temperature rising along the flow path.
2Manufacturing precision
If the wall thickness is increased downstream to compensate for temperature rise, then cooling uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the wall thickness parameter of the case along the flow path direction. Instead of maintaining a uniform wall thickness, the wall thickness parameter is varied continuously or stepwise from upstream to downstream. This single parameter change (wall thickness) achieves the dual benefit of compensating for refrigerant temperature rise and maintaining cooling uniformity, while avoiding the need for complex multi-component structures or active control systems.
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
Prevents uneven cooling by maintaining consistent refrigerant temperature and cooling efficiency throughout the flow path, enhancing the machine's thermal management and assembly ease.
Implementation Method 1
Cooling the stator from the outside by cooling the case with the refrigerant prevents overheating of the rotating electric machine
Implementation Method 2
the temperature of the refrigerant flowing through the flow path may rise as progress from the inflow side toward the outflow side of the flow path
Data Source
AI summary
A rotating electric machine case includes: a body in a hollow shape; and a flow path, provided between an inner circumferential portion and an outer circumferential portion of the body, configured to allow a refrigerant to pass from one end portion toward the other end portion in an axial direction of the body. In addition, an inner diameter of the body is constant in the axial direction of the body, and a dimension from the inner circumferential portion of the body to the outer circumferential portion of the body is larger on a downstream side of the flow path than on an upstream side of the flow path.