Abstract:
A rotating machine has a shaft rotatable about an axis, a rotor rotatable with the shaft, and a rotor end winding at an axial end of the rotor. A stator is spaced from the rotor and forms a gap therebetween. The stator comprises a stator winding. A fluid system directs fluid through to the stator. A baffle to diverts fluid away from the gap and toward the stator.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 14/568,148, which was filed Dec. 12, 2014. 
     
    
     BACKGROUND 
       [0002]    This application relates to improvements in cooling rotating electrical machines. 
         [0003]    One type of rotating electrical machine is a generator. A generator includes a rotor driven by a power source to rotate relative to a stator. The relative rotation of the rotor adjacent to the stator generates electrical power, thus converting mechanical energy into electrical energy. The electrical power is utilized for various purposes. 
         [0004]    Another rotating electrical machine may be a motor. A motor includes a rotor having conductors for carrying current to interact with magnetic fields in a stationary stator. This electromagnetic interaction between the rotor and stator generates forces that turn a shaft, converting electrical energy into mechanical energy for various purposes. 
         [0005]    Both generators and motors have air gaps between their respective rotors and stators. 
         [0006]    Rotating electrical machines may rotate at high speeds and generate significant heat. The machines may be cooled by cooling liquid. For liquid cooled high speed machines, there is a propensity for cooling fluid to enter the air gap between the rotor and stator. Fluid in the air gap may result in frictional loss causing reduced efficiency and reduced reliability. 
       SUMMARY 
       [0007]    A rotating machine has a shaft rotatable about an axis, a rotor rotatable with the shaft, and a rotor end winding at an axial end of the rotor. A stator is spaced from the rotor and forms a gap therebetween. The stator comprises a stator winding. A fluid system directs fluid to the stator. A baffle diverts fluid away from the gap and toward the stator. 
         [0008]    These and other features may be best understood from the following drawings and specification. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  schematically shows an example rotating machine. 
           [0010]      FIG. 2  shows a sectional view of the example rotating machine. 
           [0011]      FIG. 3  schematically shows the fluid path through the rotor end winding of the example rotating machine. 
           [0012]      FIG. 4  schematically shows the fluid path with a baffle. 
           [0013]      FIG. 5 a    shows a front view of an example baffle. 
           [0014]      FIG. 5 b    shows a cross-sectional view of the example baffle in  FIG. 5   a.    
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Referring to  FIG. 1 , an example rotating electrical machine  10  includes a shaft  12  that rotates about an axis “A.” A rotor  14  rotates with the shaft  12  relative to a stator  16  radially outward of the rotor  14 . The stator  16  may include stator windings  18  on its inner diameter. A gap  20  is provided radially between the rotor  14  and the stator  16  allowing for rotation of the rotor. Through this rotation, the electrical machine  10  converts mechanical energy into electrical energy. Although the example electrical machine  10  is a generator, the electrical machine  10  could be any rotating machine, including a motor. 
         [0016]    Because the operation generates significant heat, the example rotating electrical machine  10  is liquid cooled. As shown in  FIG. 2 , cooling fluid flows (flowpath F) through a hollow interior  22  of the shaft  12 . The shaft  12  includes an orifice  24 . Centrifugal force from rotation causes the fluid to exit the shaft  12  through the orifice  24 . 
         [0017]    That fluid then flows radially outward through and around the rotor end windings  26  (See  FIG. 3 ), including between the plurality of coils  28 , to cool the rotor end windings  26 . The rotor end windings  26  are provided at an axial end of the rotor windings  30  of rotor  14 . Electromagnetic interaction between the rotor windings and the stator windings  18  converts mechanical energy into electrical energy, as is known by one of ordinary skill in the art. In the example, fluid continues to travel radially outward toward the stator windings  18  to provide cooling to the stator windings  18 . 
         [0018]    Referring to  FIG. 4 , the fluid has a propensity to flow into the gap  20  between the rotor  14  and the stator  16 . Fluid in the gap  20  would cause frictional (windage) loss due to viscous shearing of the fluid within the gap during rotation, greatly reducing efficiency. A baffle  32  is thus placed adjacent to the gap  20  to divert fluid away from the gap  20 . 
         [0019]    The example baffle  32  is attached to the inner diameter of the stator winding  18  and is axially outward of the rotor  14  and the gap  20 . The baffle  32  includes an edge  34  extending radially outward as it extends axially away from the gap  20  to deflect fluid axially away from the gap  20  and radially toward the stator winding  18 . The cross section of the example baffle  32  may be triangular in shape. The baffle  32  is thus positioned such that the edge  34  is provided by the hypotenuse of the triangular cross section, which is angled to deflect fluid axially away from the gap  20  and toward the stator winding  18 . The radially inner end  35  of edge  34  is radially inward of the radially outward surface  37  of rotor  14 . While a triangular shape is shown, other shapes are contemplated. In one embodiment, the edge  34  may be curved. 
         [0020]    As shown in  FIGS. 5 a  and 5 b   , the example baffle  32  extends around the entire circumference of the stator winding  18 . As one alternative embodiment, the baffle  32  may extend around a partial circumference of the stator winding  18 . 
         [0021]    In the example, referring back to  FIG. 2 , fluid exits the orifice  24  and flows radially outward through the end winding support  36  attached to the axial end of the rotor  14 . The end winding support  36  provides support for the rotor end windings  26  and is radially between the shaft  12  and the rotor end windings  26 . The end winding support  36  includes a channel  38  aligned with the orifice  24  for directing fluid radially outward toward the rotor end windings  26 . 
         [0022]    After the fluid travels around and through the rotor end windings  26 , it continues to flow radially outward toward an end ring  40  configured to hold the rotor end winding assembly together. The fluid then flows radially outward of the end ring  40  toward the stator winding  18 , flowing either axially inward (flowpath fi) or axially outward (flowpath fo) of the end ring  40 , as shown in  FIG. 4 . The fluid fi has a propensity for entering the gap  20 . Thus, the baffle  32  is placed between fluid path fi and the gap  20  to divert fluid away from the gap and toward the stator winding  18 . 
         [0023]    Although the example disclosed is an electrical machine having wound rotors and stators, the features described are not limited to those types of machines and may be used in any rotating machines. 
         [0024]    Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.