Dynamo-Electric Machine Stator Cooling Passage Design
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Solution Overview
Problem
In rotating electric machines using indirect cooling methods, the temperature rise at the stator end portion is higher than at the central portion due to uneven heat transfer and cooling liquid temperature variations, leading to reduced cooling performance near the outlet.
Innovation Solution
The cooling liquid passage in the housing has varying heights in the radial direction depending on the axial position, with larger cross-sectional areas at the inlet and smaller areas at the outlet to enhance heat transfer and mitigate temperature rises at the stator end and central portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If indirect cooling method is used with uniform cooling liquid passage, then cooling structure is simple, but temperature rise at stator end portion becomes higher than at central portion
Solution Approach 1:
The cooling liquid passage is designed with different heights in the radial direction at different axial positions. Specifically, the passage height is larger at the end portions of the stator and smaller at the central portion, creating local variations in cooling capacity that match the local heat generation patterns. This resolves the contradiction by making the cooling structure non-uniform to address the temperature rise problem while maintaining overall structural simplicity.
2Ease of manufacture
If cooling liquid passage has constant cross-sectional area, then manufacturing is easy, but cooling performance deteriorates near cooling liquid outlet
Solution Approach 1:
The cooling liquid passage cross-sectional area is varied along the axial direction, with larger areas at the inlet side and smaller areas at the outlet side. This local variation compensates for the temperature rise of cooling liquid as it flows through the system, maintaining effective cooling performance throughout the stator length while keeping the manufacturing process relatively simple through standardized forming techniques.
3Loss of energy
If cooling liquid temperature rises along flow direction, then heat absorption is effective, but heat radiation performance decreases near outlet
Solution Approach 1:
The cooling liquid passage is designed with larger cross-sectional area at the inlet portion where cool liquid enters, maximizing heat absorption capacity. As the cooling liquid flows toward the outlet and its temperature rises, the passage area gradually decreases, which maintains the temperature gradient and heat transfer efficiency. This local adaptation of passage dimensions resolves the contradiction between effective heat absorption and maintaining heat radiation 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
This configuration improves cooling performance by maintaining lower temperatures at the stator end and central portions, effectively reducing temperature rises and enhancing overall cooling efficiency.
Implementation Method 1
the copper loss generated at the stator coil thick portion is transferred to the stator core in contact therewith and the heat is radiated to the cooling liquid via the housing
Implementation Method 2
the cooling liquid absorbs the heat radiated from the stator while flowing in the passage in the housing
Data Source
AI summary
A dynamo-electric machine reduces the increase in temperature of a stator close to a cooling liquid outlet and a stator end portion, and that has excellent cooling performance. The dynamo-electric machine is provided with: a stator, a rotor that is held on the inner-diameter-side of the stator across a predetermined gap so as to be capable of rotating; and a housing that is located on the outer-diameter-side of the stator and holds the stator and the rotor. The housing is provided with a cooling liquid channel through which a cooling liquid flows, the radial height of the cooling liquid channel within the housing differing depending on the axial position of the rotor.