Abstract:
A motor that includes a motor frame, an end-bell assembly, a stator assembly, and filling material is described. The stator assembly is placed within the frame such that at least one open area is defined between an inner diameter of the stator assembly and an inner diameter of the motor frame. The at least one end-bell assembly is attached to the motor frame, forming an inside area adjacent the motor frame and the stator assembly. The motor also includes a material configured to fill the at least one open area and the inside area of the at least one end-bell assembly for the purpose of sealing the stator assembly and the inside area associated with the at least one end-bell assembly. The material assists in a bonding and attachment between any two or more of the stator assembly, the motor frame, and the at least one end-bell assembly.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to electric motors, and more specifically, to methods and apparatus that configure motors for application in a high moisture environment. 
         [0002]    It is known that certain electric motors tend to fail in wet or high moisture applications. Examples of such applications include those where there is an exposure to saltwater or where there are frequent cleanings and wash-downs near the motor with caustic solvents, such as might be found in food processing areas. In such applications, bearing and stator failures are common. 
         [0003]    One known approach to mitigating these motor failures is to use gaskets, o-rings, sealing washers, and seals on assembled joints and on the motor shaft to control the amount of contaminates that are able to enter the motor. In other applications, a hydrophobic breather may be used to allow the motor to “breathe”, without pulling in moisture. 
         [0004]    Another known approach is to apply an encapsulating material on the stator to protect stators or stators inside frames. However, these motors do not incorporate the encapsulating material such that end-bell joints are sealed. Nor is the encapsulating material utilized to hold parts of the motor together or reduce the amount of air inside the motor for purposes of minimizing breathing. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    In one aspect, a motor that includes a motor frame, at least one end-bell assembly, a stator assembly, and a filling material is provided. The stator assembly is placed within the motor frame such that at least one open area is defined at a location between an inner diameter of the stator assembly and an inner diameter of the motor frame. At least one end-bell assembly is attached to the motor frame, thereby forming an inside area adjacent the motor frame and the stator assembly. The motor includes a material configured to fill the at least one open area and the inside area of the at least one end-bell assembly for the purpose of sealing the stator assembly and the inside area associated with the at least one end-bell assembly. The material assists in a bonding and attachment between any two or more of the stator assembly, the motor frame, and the at least one end-bell assembly. 
         [0006]    In another aspect, a method for assembling a motor is provided. The method includes inserting a stator assembly, including a rotor bore, within a motor body, inserting a bore plug into the rotor bore, attaching an end-bell assembly to the motor body, and filling any open areas of the stator assembly, any open areas between the motor body and stator assembly, and any open areas between the end-bell assembly and the motor body with a material to seal the stator assembly and to seal or bond an interface between the end-bell assembly and the motor body. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is an illustration of an electric motor. 
           [0008]      FIG. 2  is side cross-sectional view of a stator assembly within a motor body. 
           [0009]      FIG. 3  is an end view of the motor body of  FIG. 2 . 
           [0010]      FIG. 4  is an exploded, perspective view of an end-bell assembly. 
           [0011]      FIG. 5  is a side cross-sectional view of a rotor assembly configured for insertion into the motor body of  FIG. 2 . 
           [0012]      FIG. 6  is a side cross-sectional view of a rotor assembly inserted into the motor body, and the end-bell assembly attached to the motor body. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]      FIG. 1  is an illustration of an electric motor  14 . Electric motor  14  includes a motor shell  16 , which is sometimes referred to as a frame. Electric motor  14  may be, for example, but not limited to, a direct current motor, an alternating current motor, a split-capacitor motor, a capacitor-start motor, an electronically commutated motor, and a brushless direct current motor. Within motor shell  16 , electric motor  14  includes a stator assembly  18  and a rotor  20 . A shaft  22  extends through rotor  20 . A power supply (not shown in  FIG. 1 ) and/or a control module (not shown in  FIG. 1 ) are coupled to electric motor  14  through a cable  24 . However as described above, motors such as electric motor  14  have been known to fail in high moisture environments. 
         [0014]      FIG. 2  is a cross-sectional view of a fully filled or potted motor body  100 , or motor frame, which is configured for operation in a high moisture environment. Potted motor body  100  includes a plurality of materials, for example, a potting material  102  that is utilized to fill one or more open areas associated with a stator assembly  104  and a potting material  106  that is utilized to fill an area defined by the motor body  100  that is not occupied by the stator housing  104  or a rotor assembly (not shown in  FIG. 2 ). When the various potting materials  102  and  106  are to be injected into their designated locations, a bore plug  110  is inserted into an area of the motor body  100  associated with a rotor (not shown). The bore plug  110  is utilized to maintain a placement of the potting materials  102  and  106 , for example, during a curing process. As further explained herein, once the bore plug  110  is removed, a rotor assembly can be inserted into the motor body  100 . While described herein as a potting material, it should be understood that such descriptions also refer to a resin compound or other material that could be utilized in the application described herein. 
         [0015]    Stator leads  130  are used for connecting the stator assembly  104  to a power source located within an end-bell assembly (shown in  FIG. 4 ). The stator leads  130 , in one embodiment, extend from the stator assembly  104 , through the potting material, and exit stator assembly  104  at a potted lead exit, denoted by  132 . With such a configuration, outside contaminates and moisture cannot enter the motor body  100  through the potted lead exit  132 . 
         [0016]      FIG. 3  is an end view of a motor body  100  to which a motor end-bell assembly  150  (shown in  FIG. 4 ) is to be attached. The motor end-bell assembly  150  includes electronic components utilized in the operation of a motor of which motor body  100  forms a part. As illustrated, a layer of potting material  120  (also shown in side view in  FIG. 2 ) is incorporated into an end  130  of motor body  100  to seal an interface between a motor end-bell and motor body  100 . 
         [0017]      FIG. 4  is an exploded, perspective view of an end-bell assembly  150  that includes an end-bell cover  152 , an o-ring  154 , an end-bell  156  (containing the aforementioned electronic components), and a layer of potting material  158 . In the exemplary embodiment, one end-bell assembly  150  is attached to motor body  100 , however, multiple end-bell assemblies  150  may be included. Potting material  158  is utilized to seal an inside area of the end-bell assembly  150  that is, upon completion of motor assembly, adjacent to the motor body or frame  100  (shown in  FIG. 2 ). End-bell  156  includes a port  159  through which a user of the motor makes their electrical connections. 
         [0018]    The end-bell assembly houses capacitors  160  and  162 , electronic switches  164 , and any other auxiliary components, controls, and electrical connections necessary for motor operation, accessible by removing a threaded cover (e.g., end-bell cover  152 ), allowing for easy access for installation and servicing of the motor and auxiliary components. With this configuration, no additional junction box is required, at least for certain motor configurations, eliminating extra places for contaminates to get trapped within the motor. Additionally,  FIG. 4  also illustrates mechanical assemblies  168  which are utilized for mechanical mounting of switches  164 . As described above, the stator leads  130  (shown in  FIG. 2 ) used for connecting to a power source are fully potted within connection area  170  utilizing potting material, so outside contaminates and moisture cannot enter the motor through this connection area  170 . 
         [0019]    In one embodiment, end-bell cover  152  is a threaded stainless steel cover for accessing the electrical connections that are utilized in a motor application. As described above, such connections are made through port  159 . Such a configuration eliminates cover fasteners, which might be misplaced during motor installation. As mentioned above, one embodiment of the cover  152  incorporates o-ring  154  in addition to threads, to fully seal out contaminates from entering the conduit connection area. 
         [0020]    The construction of a motor utilizing the potting materials as described with respect to  FIGS. 2-4  reduces points of entry for contaminates, while also reducing the need for additional components used for sealing the motor, such as additional o-rings, gaskets, and sealing washers. Such construction further minimizes the amount of air inside the motor, so it is less likely to “breathe” and pull in moisture from the outside thereby protecting internal components, such as bearings and stator windings, from premature failure due to excessive moisture exposure. 
         [0021]    Additionally, the potting materials described herein assist in bonding the stator assembly  104  and/or the end-bell assembly  150  to the frame (e.g., motor body  100 ), reducing the number of fasteners required to hold the motor together, while also extending the ability of the motor to handle increased mechanical vibration and shock loads. 
         [0022]    As described with respect to  FIGS. 2-4 , the stator leads  130  used for connecting to a stator power source are fully potted utilizing the potting material  132 , so outside contaminates and moisture cannot enter the motor body  100  through the conduit connection area. This motor configuration uses the end-bell assembly  150  as a form for the potting material, simplifying the tooling necessary for holding the potting materials in place during a curing process. The above described bore plug  110  is the only tooling needed for the potting material step of the motor fabrication process. 
         [0023]      FIG. 5  is a side cross-sectional view of an exemplary rotor assembly  200  configured for insertion into the motor body  100  described with respect to  FIG. 2 . Rotor assembly  200  incorporates a rotor core  201 , a bearing carrier  202 , bearings  204  and  206 , and a shaft  208 . Shaft  208  may be, for example, and not limited to, a two piece shaft and a press-fit shaft. In one embodiment, bearing carrier  202  provides an ease of motor assembly as well as ease in motor service and bearing replacement, while maintaining the above described sealing integrity of the motor frame  100  and end-bell assembly  150  enclosure. 
         [0024]      FIG. 6  is a side cross-sectional view of rotor assembly  200  inserted into the motor body  100 , and the end-bell assembly  150  attached to the motor body  100 . The bearing carrier  202  is configured such that it fits inside an end cap pilot  209 , protecting the joint with the customer&#39;s mounting (gearbox, pump, etc.) when applicable. Bearing carrier  202  also incorporates an o-ring  210 , and a shaft seal  212 . The o-ring  210  engages the motor body  100  for sealing purposes. 
         [0025]    The above described configuration helps prevent contaminates from entering the inside area of the motor. The o-ring  210  engages the motor body  100 , and an end cap  214  engages the potting materials  102  and  106  for sealing purposes. 
         [0026]    With respect to the above described embodiments, the number of points of entry for contaminates have been greatly reduced, as compared to other motor configurations, by using a resin based or other potting material to affix the end-bell assembly  150  and end cap  214  to the motor housing or body  100 . This potting material seals the joints between the motor body  100  and the end-bell assembly  150  and the rotor assembly  200 . The potting materials described herein minimize the amount of air inside the motor, so the motor is less likely to “breathe” and pull in moisture from the outside. The potting materials also assist in bonding the stator assembly  104  and end-bell assembly  150  to the motor body  100 , which may extend the ability of the motor to handle increased vibration and shock loading, and also reduces the number of fasteners required for holding the motor together. 
         [0027]    The configuration described herein uses the end-bell assembly  150  and the end cap  214  associated with the rotor assembly as a form for the resin, simplifying the tooling necessary for holding the potting material in place during curing. A simple bore plug  110 , described above, is the only tooling for potting of the stator assembly  104 . The rotor assembly  200 , which is sometimes referred to as a cartridge, which includes the bearings  204  and  206 , seals, shaft  208 , and rotor core  201  can be removed from the motor body  100  and/or replaced as a single assembly. The configuration described herein may be applied to motors that include motor mounts, flanges, and/or motor feet for positioning and/or stabilizing the motor. Such a combination of features results in an improved motor design to improve the ability of the motor to survive hostile environments such as those where caustic solvents and frequent wash downs are likely to be utilized, such as in food processing applications. 
         [0028]    While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.