Patent Document

FIELD OF THE INVENTION 
       [0001]    The invention relates generally to stator assemblies and more particularly to stator assemblies for use in fluid cooled motors. 
       BACKGROUND OF THE INVENTION 
       [0002]    An electric motor generates heat during operation. If the heat is not adequately dissipated, a performance and a reliability of the motor may be impaired. It has been an object of prior art motors to provide efficient and cost effective methods for dissipating heat generated by the motors to maximize the performance and the reliability thereof. 
         [0003]    One such method is disclosed in commonly owned U.S. Pat. No. 7,002,267, hereby incorporated herein by reference in its entirety. The &#39;267 patent illustrates a motor including a rotor and a stator assembly. The stator assembly, such as that disclosed in commonly owned U.S. Pat. No. 4,076,989, incorporated herein by reference in its entirety, typically includes a hollow main body portion disposed around a rotor or shaft, end plates, and a cooling means. A magnetic field generated by the stator assembly causes a rotation of the rotor to produce mechanical energy. The motor disclosed in the &#39;267 patent includes a plurality of coolant apertures. A pressurized coolant is caused to flow through the coolant apertures to cool the stator. 
         [0004]    The manufacture of stator assemblies can be a timely and expensive process. Typical manufacturing steps include: shrink fitting an aluminum layer having machined fluid channels onto a stator, shrink fitting a cooling jacket over the aluminum layer, and finishing the assembly with aluminum end plates. It has been a continuing challenge to minimize the complexity and cost of manufacturing stator assemblies while maximizing a performance thereof. 
         [0005]    It would be desirable to produce a stator assembly for use in a fluid cooled motor, wherein a complexity and a cost of manufacture of the stator assembly are minimized, and a performance and a cooling capability of the stator assembly are maximized. 
       SUMMARY OF THE INVENTION 
       [0006]    Harmonious with the present invention, a stator assembly for use in a fluid cooled motor, wherein a complexity and a cost of manufacture of the stator assembly are minimized, and a performance and a cooling capability of the stator assembly are maximized, has surprisingly been discovered. 
         [0007]    In one embodiment, a stator assembly comprises a hollow main body adapted to receive a rotor therein; and a cooling jacket disposed around the main body, wherein the cooling jacket includes at least one conduit adapted to receive a coolant therein. 
         [0008]    In another embodiment, a stator assembly for use in a fluid-cooled motor comprises: a hollow main body having a first end and a second end and adapted to receive a rotor therein; a cooling jacket disposed around the stator, wherein the cooling jacket includes at least one conduit adapted to receive a coolant therein; a first end plate disposed on the first end of the main body; and a second end plate disposed on the second end of the main body. 
         [0009]    A method for producing a stator assembly for use in a fluid-cooled motor comprises the steps of: providing a main body having a hollow interior adapted to receive a rotor therein; and forming a cooling jacket around the main body; wherein the cooling jacket includes at least one conduit. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0010]    The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: 
           [0011]      FIG. 1  is a front sectional view of a stator assembly in accordance with an embodiment of the invention; 
           [0012]      FIG. 2  is a side cross sectional view of the stator assembly illustrated in  FIG. 1  taken along line  2 - 2 ; and 
           [0013]      FIG. 3  is a front sectional view of a stator assembly in accordance with another embodiment of the invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0014]    The following detailed description and appended drawings describe and illustrate various exemplary embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. In respect of the methods disclosed and illustrated, the steps presented are exemplary in nature, and thus, the order of the steps is not necessary or critical. 
         [0015]      FIGS. 1 and 2  show a stator assembly  10  in accordance with an embodiment of the invention. The stator assembly  10  is adapted to be used in a motor (not shown). 
         [0016]    The stator assembly  10  includes a cylindrical hollow main body portion  12  having a longitudinal axis X. In the embodiment shown, the main body portion  12  is formed from an iron alloy. It is understood that other materials can be used to form the main body portion  12  without departing from the scope and spirit of the invention. The main body portion  12  is disposed around a rotor assembly  14  which is coupled to a driven member (not shown) such as a traction drive, a pump impeller, or a compressor impeller, for example, by a shaft  16 . 
         [0017]    The stator assembly  10  also includes a cooling jacket  18  disposed around and in thermal communication with the main body portion  12 . In the illustrated embodiment, the cooling jacket  18  is formed from aluminum. However, other materials can be used to form the cooling jacket  18  as desired. The cooling jacket  18  includes a plurality of fluid conduits  20  formed therein. In the embodiment shown, the fluid conduits  20  are formed substantially parallel to the longitudinal axis X of the main body portion  12 . It is understood that the fluid conduits  20  can be formed between the cooling jacket  18  and the main body portion  12  or otherwise, and can be formed in different directions and orientations as desired. The fluid conduits  20  are adapted to receive a coolant (not shown) from a source of coolant (not shown) therein. 
         [0018]    A first end plate  22  is disposed on a first end  24  of the stator assembly  10 . The first end plate  22  forms a substantially fluid tight seal with the first end  24  of the stator assembly  10 . A pair of apertures (not show) is formed in the first end plate  22  for receiving one of an inlet fitting  23  and an outlet fitting  25  therein. The fittings  23 ,  25  are in fluid communication with the fluid conduits  20  formed in the cooling jacket  18  and the source of coolant. The first end plate  22  also includes a central groove  26  formed in a first surface  28  thereof. The central groove  26  receives a first bearing  30  that rotatingly supports the shaft  16 . It is understood that the first bearing  30  can be any type of bearing as desired such as an air bearing and a ball bearing, for example. Optionally, one or more coolant channels (not shown) can be formed in the first end plate  22 . The coolant channels formed in the first end plate  22  can be in fluid communication with the inlet fitting  23 , the outlet fitting  25 , and/or the fluid conduits  20  formed in the cooling jacket  18  as desired. 
         [0019]    A second end plate  32  is disposed on a second end  34  of the stator assembly  10 . The second end plate  32  forms a substantially fluid tight seal with the second end  34  of the stator assembly  10 . The second end plate  32  includes a central groove  36  formed in a first surface  38  thereof adapted to receive a second bearing  40  that rotatingly supports the shaft  16 . It is understood that the second bearing  40  can be any type of bearing as desired such as an air bearing and a ball bearing, for example. A central aperture (not shown) is formed in the second end plate  32 . The shaft  16  extends through the central aperture to the driven member. Optionally, one or more coolant channels (not shown) can be formed in the second end plate  32 . In this case, the fluid conduits  20  formed in the cooling jacket  18  would extend to the second end  34  of the stator assembly  10  and be in fluid communication with the coolant channels formed in the second end plate  32 . 
         [0020]    To produce the stator assembly  10 , a mold (not shown) for the cooling jacket  18  is disposed around the main body portion  12  and the cooling jacket  18  is cast directly over the main body portion  12 . As the cooling jacket  18  is being molded, the fluid conduits  20  are injection molded into the cooling jacket  18 . It is understood that the cooling jacket  18  can be formed prior to disposal over the main body portion  12  as desired. It is also understood that the fluid conduits  20  can be formed in the cooling jacket  18  subsequent to the molding of the cooling jacket  18  as desired. It is further understood that the mold for the cooling jacket  18  may include structure for forming the fluid conduits  20  as desired. 
         [0021]    The main body portion  12  and the cooling jacket  18  are disposed around the rotor assembly  14  and the shaft  16 . The first end plate  22  including the first bearing  30  is sealed to the first end  24  of the stator assembly  10  and the shaft  16  is rotatably secured in the first bearing  30 . It is understood that the first end plate  22  can be sealed to the first end  24  of the stator assembly  10  by any means, such as with tie rod screws (not shown), for example. The inlet fitting  23  and the outlet fitting  25  are disposed in the apertures formed in the first end plate  22  to communicate with the fluid conduits  20  formed in the cooling jacket  18 . 
         [0022]    The shaft  16  is inserted through the central aperture formed in the second end plate  32 . The second end plate  32 , including the second bearing  40 , is sealed to the second end  34  of the stator assembly  10 , and the shaft  16  is rotatably secured in the second bearing  40 . It is understood that the second end plate  32  can be sealed to the second end  34  of the stator assembly  10  by any means, such as with tie rod screws (not shown), for example. 
         [0023]    In use, the shaft  16  is coupled to the driven member. A magnetic field is generated by the stator assembly  10 , which causes the rotor assembly  14  and the shaft  16  to rotate about the longitudinal axis X of the main body portion  12 . The rotation of the rotor assembly  14  and shaft  16  is transferred to the driven member. Heat is produced during operation of the stator assembly  10 . Coolant from the coolant source is caused to flow into the inlet fitting  23  and through the first end plate  22  into the fluid conduits  20  formed in the cooling jacket  18 . The coolant absorbs heat energy from the main body portion  12  to cool the main body portion  12 . If coolant channels are formed in the endplates  22 ,  32 , coolant flowing therethrough can be used to cool the first end  24  and the second end  34  of the stator assembly  10 . The coolant then flows out of the stator assembly  10  through the outlet fitting  25 . The coolant can be recirculated between the coolant source and the fluid conduits  20  formed in the cooling jacket  18  to maintain the temperature of the stator assembly  10  within a desired range. 
         [0024]      FIG. 3  shows a stator assembly  110  in accordance with another embodiment of the invention. Similar structure discussed above for  FIGS. 1 and 2  includes the same reference numeral followed by a prime “′” symbol. A conduit  111  is disposed in a mold (not shown) for forming a cooling jacket  118 . In the embodiment shown, the conduit  111  is formed from a stainless steel alloy. It is understood that other materials may be used to form the conduit  111 , such as an aluminum alloy or brass, for example. The conduit  111  includes a fluid inlet  123  and a fluid outlet  125  in fluid communication with a source of coolant. Although the conduit  111  is shown, as a helically wound coil, other conduit shapes and flow patterns can be used as desired. 
         [0025]    To form the cooling jacket  118 , the conduit  111  is disposed around a main portion  12 ′ of the stator assembly  110 . The cooling jacket  118  is molded around the conduit  111 . The fluid inlet  123  and the fluid outlet  125  are then connected to the source of coolant to provide fluid communication between the source of coolant and the conduit  111 . The remaining assembly process for the stator assembly  110  is substantially the same as described above for  FIGS. 1 and 2 . 
         [0026]    In use, the stator assembly  110  is coupled to a driven member (not shown) as described above for  FIGS. 1 and 2 . A magnetic field is generated by the stator assembly  110  which results in the generation of heat. Coolant from the coolant source is caused to flow through the conduit  111 . The coolant absorbs heat energy from the main body portion  12 ′. The coolant can be recirculated between the coolant source and the piping  111  disposed in the cooling jacket  118  to maintain the temperature of the stator assembly  110  within a desired range. 
         [0027]    From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.

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