Ufa University of Science and Technology (UUNiT) has patented a design for an electric machine with liquid cooling for both the rotor and stator. The utility model, described in the FIPS database, details a system that supplies coolant through a hollow shaft, passes it through the magnetic core channels, and directs it to the end windings of the stator.
A distinctive feature of the design is the internal cavities in the rotor end discs, connected to the hollow shaft channels and the axial channels of the magnetic core. The radial holes in the discs are angled at 15–45 degrees to the axis of rotation and directed towards the stator winding sections extending beyond the core.
The coolant enters through the hollow shaft at a pressure of up to 0.1 MPa. The internal cavities of the end discs act as distribution manifolds: part of the coolant passes through the axial channels of the magnetic core, and part enters the radial holes. As the rotor rotates, centrifugal force helps to spray the liquid, which washes over the end windings and is then drained into the lower part of the housing or through a drainage system.
The patent claims that the design should increase cooling efficiency due to a more uniform distribution of coolant and the coordinated operation of the system's channels. The use of cavities in the end discs also eliminates the need for a separate distribution plate located in the middle of the magnetic core.
The patent states that the design can be used in electric vehicle traction drives, aviation starter-generators, high-speed industrial motors, and compressors.