Rotor Balancing Crown with Radial Cooling Ducts
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Solution Overview
Problem
The accumulation of coolant in the mechanical retaining crowns of wound-rotor electric machines leads to friction between the stator and rotor, reducing efficiency due to capillary infiltration into the air gap, which is not effectively addressed by existing cooling methods.
Innovation Solution
A mechanical retaining ring with a concave radial section and integrated evacuation ducts is designed to encircle the rotor windings, allowing for radial ejection of coolant under centrifugal force, featuring reinforcing tie rods to enhance structural integrity and facilitate coolant circulation and exit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If coolant is sprayed onto the coil heads for cooling, then cooling efficiency is improved, but coolant accumulates in the crown and infiltrates the air gap causing friction losses
Solution Approach 1:
The invention extracts the harmful accumulated coolant from the crown interior through specifically designed evacuation ducts. These ducts provide dedicated pathways for the coolant to exit the crown structure, preventing it from infiltrating the air gap and causing friction losses, while still allowing the coolant to perform its cooling function on the coil heads.
Solution Approach 2:
The evacuation ducts act as intermediary structures that mediate between the coolant accumulation problem and the air gap. They provide a controlled pathway for coolant evacuation, preventing direct contact between the accumulated coolant and the air gap, thus eliminating the harmful capillary infiltration while maintaining the cooling function.
2Stability of the object's composition
If material is removed from the crown for balancing, then rotational balance is improved, but structural strength is reduced
Solution Approach 1:
The invention segments the crown structure by introducing reinforcing tie rods that divide the crown into distinct sections. These tie rods are strategically positioned to provide structural reinforcement in areas where material has been removed for balancing, thereby maintaining both rotational balance and structural strength simultaneously.
Solution Approach 2:
The invention employs composite construction by combining the crown material with reinforcing tie rods made of high-strength material. This composite structure allows the crown to achieve the required rotational balance through selective material removal while the reinforcing tie rods compensate for the lost strength, maintaining overall structural integrity.
3Strength
If the crown structure is reinforced to maintain strength, then structural integrity is improved, but coolant circulation is hindered
Solution Approach 1:
The invention applies local quality by providing reinforcing tie rods only in specific locations where structural strength is critical, rather than uniformly reinforcing the entire crown. This localized reinforcement approach maintains structural integrity in key areas while leaving other areas open for effective coolant circulation and evacuation.
Solution Approach 2:
The reinforcing tie rods are arranged in specific three-dimensional configurations that provide structural strength without blocking the radial and axial pathways needed for coolant circulation. The spatial arrangement of the tie rods allows coolant to flow around them, maintaining productivity while achieving the required structural integrity.
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 improves cooling efficiency by preventing coolant accumulation and reducing friction, thereby enhancing the performance of wound-rotor electric machines by ensuring effective liquid distribution and exit, thus maintaining motor efficiency.
Implementation Method 1
radially evacuate the cooling liquid ejected by centrifugal force from the rotor windings
Implementation Method 2
creates a smooth surface against the internal circumferential wall of the crown which by capillarity infiltrates into the air gap
Data Source
Figure 1~3
AI summary
The invention relates to a crown (10) for mechanically holding rotor windings, which defines: - a holding ring (2), the ring having a concave radial section so as to define an annular recess (11) towards the inside of the ring (11), the recess (11) being provided for covering an end portion of rotor windings; and - a central opening (5). The crown (10) is moulded as a single piece of metal alloy, and includes at least two discharge pipes (7) capable of radially discharging cooling liquid ejected by centrifugal force from rotor windings.