Rotating Electric Machine Radial Cooling Ducts
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Solution Overview
Problem
Conventional rotating electric machines face challenges in maintaining effective cooling of field coils, particularly in radial flow cooling systems where flow rate decreases towards the center, leading to higher temperatures, and in gap pick up diagonal flow systems where complex duct structures increase production costs.
Innovation Solution
A rotating electric machine design featuring a stator and rotor with radial cooling fluid ducts that form downward and upward flow paths, communicating through sub slots, allowing for efficient circulation of cooling fluid inwardly and outwardly in radial directions, effectively cooling the field coil while simplifying the rotor structure to reduce production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If radial flow cooling system is used, then cooling structure is simple, but cooling performance deteriorates toward the center of rotor
Solution Approach 1:
The rotor is divided into multiple independent cooling units along the axial direction, each with its own radial cooling ducts and sub slots. This segmentation allows each unit to independently cool its corresponding field coil region, ensuring uniform temperature distribution while maintaining simple radial duct structures that are easy to manufacture.
Solution Approach 2:
Different regions of the rotor are provided with locally optimized cooling configurations. Each cooling unit has radial cooling ducts and sub slots positioned to match the specific thermal requirements of its corresponding field coil region, achieving uniform cooling performance throughout the rotor while keeping each local structure simple and manufacturable.
2Productivity
If rotor capacity is increased by elongating rotor axially, then machine capacity increases, but cooling uniformity deteriorates
Solution Approach 1:
The elongated rotor is segmented into multiple cooling units along the axial direction, with each unit having independent radial cooling ducts and sub slots. This allows the rotor to be scaled axially while maintaining uniform cooling performance in each segment, as each unit independently manages the thermal conditions of its corresponding field coil region without affecting other regions.
Solution Approach 2:
The cooling system transitions from a single axial flow path to multiple radial flow paths distributed along the axial dimension. By providing radial cooling ducts and sub slots at different axial positions, the system achieves uniform cooling along the axial direction while allowing the rotor to be elongated for increased capacity.
3Temperature
If gap pick up diagonal flow cooling system is used, then cooling performance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of using complex diagonal flow paths that pick up cooling fluid from the air gap, the invention inverts the approach by using simple radial cooling ducts that directly conduct cooling fluid from sub slots radially outward. This inverted radial flow configuration achieves effective cooling while maintaining simple, easy-to-manufacture duct structures.
Solution Approach 2:
The invention extracts the essential cooling function from the complex diagonal flow system and implements it through simplified radial cooling ducts with sub slots. By taking out only the necessary radial conduction path and eliminating the complex diagonal geometry, the system achieves good cooling performance with much simpler manufacturing requirements.
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 design ensures uniform cooling performance along the axial direction of the field coil, enabling the elongation of the rotor and increased capacity without increasing production costs, while maintaining efficient cooling performance.
Implementation Method 1
cooling fluid such as air or hydrogen gas is passes through the ventilation ducts so that the coils and the iron cores heated up due to the generated joule loss and iron loss are cooled down
Implementation Method 2
An axial fan 5 installed near one end of the rotor shaft 4 generates the flow of cooling fluid 6 (depicted with arrows) passing through the various ventilation ducts in the rotating electric machine
Data Source
AI summary
A rotating electric machine wherein sub slots serving as cooling fluid ducts in the axial direction are provided at the bottoms of the coil slots formed in the rotor, radial cooling fluid ducts are formed through the field coil of the rotor in the radial direction of the rotor and juxtaposed in the axial direction of the rotor, so as to communicate the sub slots with the air gap, and radial cooling fluid ducts are formed through the stator in the radial direction of the stator and juxtaposed in the axial direction of the rotor, corresponding in position to the radial cooling fluid ducts in the rotor, so as to communicate the inner periphery of the stator with the outer periphery of the stator.