Hollow Rotor Shaft Cooling via Centrifugal Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cooling systems for electrical machines with hollow rotor shafts are either inefficient in heat dissipation due to small coolant cross-sections or heavy due to large coolant volumes, and often require additional components and complex designs that increase weight and manufacturing complexity.
Innovation Solution
A hollow rotor shaft design featuring a large-volume cylindrical cavity with a distribution element that uses centrifugal force to efficiently distribute a small amount of coolant evenly across the inner surface of the cylinder jacket, minimizing weight and coolant usage while maximizing heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If small coolant cross-sections are used, then the volume requirement is reduced, but the heat dissipation efficiency deteriorates and the rotor weight is hardly reduced
Solution Approach 1:
The invention transitions from linear channel cooling to radial spray cooling by introducing a distribution element with multiple outlet openings arranged radially. This dimensional change allows coolant to be distributed across a large circumferential area of the rotor shaft surface, achieving effective heat dissipation with minimal coolant volume.
Solution Approach 2:
The cooling system is segmented into multiple outlet openings distributed around the circumference of the rotor shaft. This segmentation allows the limited coolant volume to be distributed to multiple cooling zones simultaneously, improving overall heat dissipation efficiency while maintaining low coolant consumption.
2Area of stationary object
If large line cross-sections and cavities are used, then a large surface for heat transfer and light construction are realized, but the hollow cylinder must be almost completely filled with coolant which increases the moving mass
Solution Approach 1:
The distribution element utilizes the kinetic energy of the incoming coolant flow itself to generate the radial spray pattern. The coolant's own momentum drives the distribution process without requiring additional pumps or complex mechanisms, achieving efficient cooling with minimal coolant volume and no increase in moving mass.
3Ease of operation
If forced guidance of coolant through channels is used, then the coolant can be directed to specific areas, but high pressure loss occurs and coolant pumps are necessary
Solution Approach 1:
Instead of forcing coolant through restrictive channels from the center outward, the invention inverts the approach by allowing coolant to enter and then distributing it radially through outlet openings. This inversion leverages the natural radial flow pattern and centrifugal forces to achieve distribution without high pressure losses or additional pumping requirements.
4Temperature
If additional cooling components are integrated into the rotor, then cooling effectiveness is improved, but the design complexity and manufacturing complexity increase
Solution Approach 1:
The distribution element is merged with the rotor shaft structure itself, with outlet openings formed directly in the rotor shaft. This integration eliminates the need for separate cooling channels, seals, and additional components, achieving effective cooling while maintaining simple design and manufacturing.
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 achieves efficient cooling with minimal weight increase, allowing for higher rotor performance and power-to-weight ratio, reduced pressure losses, and simplified manufacturing, while maintaining a lightweight construction.
Implementation Method 1
uses centrifugal force to efficiently distribute a small amount of coolant evenly across the inner surface of the cylinder jacket
Implementation Method 2
a cooling liquid enters the shaft cavity and the inner surface of the cylinder jacket... to achieve sufficient interaction of the cooling liquid with the rotor jacket and good heat transfer
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a hollow rotor shaft for the rotor of an electric motor, comprising a cylindrical casing which is closed at both ends by end flanges and surrounds a shaft cavity, wherein a shaft journal is formed on each of the end flanges and wherein in one of the shaft journals an inlet is provided, through which a cooling liquid enters the shaft cavity and reaches the inner surface of the cylinder, said rotor shaft also comprising a distribution element which is disposed in the shaft cavity and receives the cooling liquid entering via the inlet, guides said liquid over a rotationally symmetrical diverting surface in the direction of the inner surface of the cylindrical casing, and passes said liquid via a mouth region onto the inner surface.