Patent Application
20130076169
The subject matter disclosed herein relates to electrical machines. More specifically, the subject matter disclosed herein relates to liquid coolant flow through electrical machines.
A typical liquid cooled electric machine, in this case, a generator 100, is shown in
An electrical machine includes a rotor located at a central shaft and a stator located radially outboard of the rotor and secured at a back iron. A first baffle is coupled to the central shaft at one axial end of the rotor, the baffle extending radially outwardly from the shaft toward a baffle cavity at the back iron. A flow of coolant is urged toward the baffle cavity along the baffle via centrifugal force.
In another embodiment, an electrical machine includes two or more rotors arranged axially along a central shaft and two or more stators located at a back iron, each stator positioned radially outboard of a rotor of the two or more rotors. The machine includes a plurality of baffles, each baffle located at an axial end of a rotor of the two or more rotors. Each baffle of the plurality of baffles extends radially outwardly from the shaft toward a plurality of baffle cavities at the back iron. A flow of coolant is urged toward the plurality of baffle cavities along the plurality of baffles via centrifugal force.
A method of flowing coolant through an electrical machine includes injecting a flow of coolant substantially radially into an electrical machine cavity. The flow of coolant is urged radially outwardly along a rotating baffle located at one axial end of a rotor of the electrical machine via centrifugal force and into a baffle cavity disposed at the back iron at a radial end of the baffle.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
Shown in
The rotors 12 are located at a central shaft 18 that rotates about a shaft axis 20 and are secured thereto such that the rotors 12 rotate about the shaft axis 20 with the shaft 18. Each rotor 12 includes a rotor core 22 with one or more rotor windings 24 having a plurality of rotor conductors located at the rotor core 22. The stators 14 are located radially outboard of the respective rotors 12, and are secured to a stator back iron 26, or housing. The stators 14 include one or more stator windings 28 having a plurality of stator conductors located at a stator core 30.
As the shaft 18 rotates, a flow of coolant, for example oil 32, is urged through the shaft 18 and into a machine cavity 34 through a plurality of coolant spray openings 36 in the shaft 18. Rotation of the shaft 18 forces the oil 32 radially outwardly toward the rotor winding 24 end turns 40 and stator winding 28 end turns 42. As the oil 32 flows past or impacts rotor end turns 40 and stator end turns 42 (and other components) of the electrical machine 10, thermal energy is transferred to the oil 32 from the rotor end turns 40 and stator end turns 42 (and other components) thus cooling them.
At each rotor end 44 of each rotor 12, a baffle 46 is affixed to the shaft 18 and rotates with the shaft 18. The baffle 46 extends radially outwardly from the shaft 18 toward the back iron 26, and into a baffle cavity 48 in the back iron 26. The baffle 46 contains and directs the oil 32 toward the baffle cavity 48, via centrifugal force due to the rotation of the baffle 46. When the oil 32 flows to the baffle cavity 48, the oil 32 flows to a scavenge core 50 in the back iron 26 via gravity. The oil 32 may then reject the thermal energy gained via, for example, a heat exchanger (not shown) and may be recirculated through the electrical machine 10. The baffles 46 located between adjacent rotors 12 additionally prevent cross-flow of coolant from adjacent rotors 12, thus preventing an increased temperature at those near ends 44 of the rotors 12.
Referring now to
Referring to
The baffle 46 directing the oil 32 to the baffle cavity 48 for scavenging substantially improves scavenge performance, thus reducing a level of oil 32 in a sump thereby reducing windage and friction losses during operation of the electrical machine 10.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
