Abstract:
A shroud is provided for a dynamoelectric device such as an electric motor comprising a rotor and a wire wound stator, where the shroud fully contains the end turns of the stator wire windings, provides terminal connections for winding leads, and includes a circuitry compartment to house a temperature and current protective device.

Description:
RELATED APPLICATION DATA  
       [0001]    This application is a continuation of application Ser. No. 09/422,831, filed Oct. 21, 1999, now pending.  
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    (1) Field of the Invention  
           [0003]    This invention relates generally to dynamoelectric devices, such as electric motors, and more particularly to the stator construction of the device where the stator assembly consists of a stator having a center bore with a plurality of stator poles circumferentially spaced around the center bore. The stator poles have wiring wrapped in windings around the stator poles and the windings have end turns arranged around the stator center bore at axially opposite sides of the stator. The end turns of the windings are laced and manually positioned at opposite ends of the stator to prevent their interference with the rotor assembly in the stator center bore, the motor housing, and/or with the end plates of the motor housing.  
           [0004]    (2) Description of the Related Art  
           [0005]    In a traditional dynamoelectric device such as a motor, the stator consists of a plurality of stator poles surrounding a rotor. Devices like this are well known in the art, and one is shown generally in FIG. 1. Because such devices are well known, their assembly is only generally discussed here. The stator can be a collection of individual poles as in a segmented stator, or can be formed together as a single unit. As shown in FIG. 1, the stator poles  10 , generally, have a “I”-shaped cross-section, which creates two channels on opposite sides of a central member  12  or web of the “I”-shaped cross section. A length of wire is wrapped around the central member of the “I”-shaped cross-section forming wire windings  14  that are partially contained within the channels on opposite sides of the central member  12 . Where the wire winding exits one channel at an end of the stator pole  10 , crosses over the central member  12 , and is redirected to enter the channel on the opposite side of the central member  12 , the wire winding creates an end turn  16 .  
           [0006]    End turns  16  of the wire windings  14  are created at both axial ends of each stator pole. At times windings are formed with the end turns  16  positioned at an axial distance from the opposite ends of the stator pole  10  to provide a smooth transition as they wrap around the end of the stator pole from one channel to the other channel. At this distance from the stator pole, the end turns are grouped and bound together with laces  18 . Grouping wire windings  14  with laces  18  prevents the wire windings from interfering with subsequent assembly operations. Generally, materials such as insulated tape or common nylon electrical tie wraps are used as laces  18 . After winding, the stator assembly is assembled into a housing  20 , a rotor assembly (not shown) is inserted into the stator center bore, and end plates or end bells (not shown) are assembled over the opposite ends of the housing with the rotor shaft supported by bearings in each of the end plates.  
           [0007]    There are many methods of motor construction, and the method described herein and shown in FIG. 1, demonstrates one technique where the inside of the housing  20  is fitted to the outer wall of the stator assembly  22 . By lacing the end turns  16 , the wire windings  14  are prevented from accidentally fouling areas adjacent to the stator poles where the housing  20 , rotor assembly (not shown), or end plates (not shown) are installed. As the stator is wound, winding leads  24  are brought from the wire windings  14  around the stator pole for connection outside the stator assembly  22 . The winding leads provide current input to the stator poles  10  for the development of electromotive force, and the winding leads  24  provide connection for other electrical switching devices used to regulate current and stator controls. Winding leads  24  must be sized in length for the particular connection to be made outside the stator assembly  22 , and the winding leads are often color coded to provide assembly personnel a reference during connection to external devices.  
           [0008]    This method of stator construction has many shortcomings. Lacing the end turns  16  and grouping the winding leads  24  is a manually intensive operation, requiring significant manipulation of the wire windings. The manipulation of wire windings  14  causes quality problems. Moreover, the process of generating winding leads  24  and installing winding lead connectors adds assembly time to motor manufacturing.  
           [0009]    Misplaced end turns  16  and wire windings  14  can compromise conductivity in the stator assembly  22 . As the end turns  16  are manually positioned to clear areas adjacent to the stator poles  10  for the housing  20 , the rotor assembly, or end plate installation, grounding of the wire windings can occur. Generally, the wound stator poles  10  are press fit into the housing  20 . During this operation, loose winding wires can be accidentally crimped or damaged against the housing  20 . End plates (not shown) are often mechanically fastened to the housing  20 . Similarly, during this phase of motor construction, loose winding wires can be accidentally crimped or damaged when the end plates are bolted to the housing. When the rotor assembly (not shown) is installed into the stator assembly bore it is critical that the wire windings  14  and end turns  16  do not foul the interface or air gap between the rotor assembly and the stator assembly bore. Often rotor assembly installation is a blind installation, where the end plates obscure viewing of the rotor assembly. It is important that the wire windings and end turns clear the rotor and shaft of the rotor assembly and the bearing assemblies to be fitted thereon.  
           [0010]    Protective sealant is applied to the stator assembly  22  and housing to prevent humidity from damaging the wire windings  14  when the motor is de-energized after a period of operation. The protective sealant also provides electrical insulation for the wire windings  14  from other components and debris. This sealant can become cracked if manual manipulation of the end turns  16  and wire windings  14  is needed when the stator assembly  22  is assembled with the housing, the end shields, and the rotor assembly.  
           [0011]    Generation of the winding leads  24  is another manual operation required when winding the stator poles. Winding leads  24  must be properly sized in length after winding to allow proper connection to switching devices outside the stator assembly. The winding leads  24  must be specially marked for terminal points, which vary depending upon customer requirements and motor configuration. The length of the winding leads  24  must be sufficient to allow connection to the terminal points, and the ends of the winding leads  24  must be fitted with connectors. These connectors must be specifically configured for the specific terminal point and connector style required for the customer application. Often, winding leads  24  and connectors are color coded to assist assembly personnel in making proper connections. In the prior art mechanical connectors and shrink caps on winding leads  24  have been used to provide connections to terminal points. However, the preparation of winding leads  24  in this manner creates non-standard interfaces for motor construction. This creates inflexibility in the manufacturing lines and slows overall motor production rates.  
           [0012]    The winding leads  24  and the connectors attached thereon are frequently used during inspection and testing. Manual connection and disconnection at these points during this phase of the manufacturing process is also labor-intensive. Quality can be compromised as protective sealant is sometimes damaged from the areas of the leads where connection and re-connection was made.  
           [0013]    The problems set forth above could be overcome by a device that attaches to the stator assembly  22  of the motor and contains the winding leads  24  and end turns  16  therein, thus eliminating manual lacing of the winding end turns. The device would also have a terminal container to provide uniform connector styles for winding leads. Additionally, the device would be provided with a compartment for housing protectors such as temperature and current overload circuitry.  
         SUMMARY OF THE INVENTION  
         [0014]    The shortcomings of the prior art of FIG. 1 are overcome by the present invention which provides a device that contains the end turns of a stator and provides a convenient mechanism for the connection of winding leads of the stator. In general, the invention will be used on the stator assembly such as that shown in FIG. 1, comprising a plurality stator poles, which are wound with wire and arranged in a cylindrical orientation to create an outer diameter adapted for accepting a housing and an inner diameter shaped to accept a rotor assembly (not shown). The wire windings will have end turns positioned at the opposite axial ends of the stator poles. Comprised with the wire windings are the winding leads.  
           [0015]    [0015]FIG. 4 shows the apparatus of the invention installed on one end of a stator such as that shown in FIG. 1 and described earlier. It should be understood that this particular stator shown and described is only one illustrative environment in which the apparatus of the invention may be employed. The apparatus may be employed with other types of stators. Furthermore, the description of the apparatus to follow is not intended to limit the combinations of configurations of the invention, but to describe the most detailed embodiment. Depending upon style of dynamoelectric device and customer requirements, certain features of the invention can be eliminated without departing from the scope of the invention.  
           [0016]    The apparatus of the invention comprises a generally circular shroud that has a “U” shaped cross-section. In the preferred embodiment, the shroud is molded of an insulating plastic, although other materials may be used. The cross section is shaped to entirely contain the end turns and winding leads. The shroud is connected to an axial end of the stator assembly by means of stator slot posts, which are press fit into slots created by adjacent stator poles. Molded to the shroud is a terminal container to which the winding leads are attached. Molded into the shroud is a circuitry compartment that houses current and temperature sensing devices. Above the circuitry compartment is a protector cover to hold the temperature and current sensing devices inside the circuitry compartment. Across the protector cover is a clamp that holds the protector cover to the shroud.  
           [0017]    The shroud can be fitted to both axially opposite ends of the stator assembly. When a shroud is fitted to both ends of the stator assembly, it is possible one shroud may be constructed without the terminal container, circuitry compartment, or protector cover.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    Further objectives and features of the invention are revealed in the following detailed description of the preferred embodiment of the invention and in the drawing figures wherein:  
         [0019]    [0019]FIG. 1 is an end view of an opened housing, exposing the stator poles and wire windings showing prior art methods of lacing end turns and grouping winding leads.  
         [0020]    [0020]FIG. 2 is an exploded view of the apparatus of the invention.  
         [0021]    [0021]FIG. 3 is an assembled view of the apparatus of the invention.  
         [0022]    [0022]FIG. 4 is a view of the apparatus of the invention fully assembled on the stator assembly of FIG. 1.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]    [0023]FIGS. 2 and 3 show the apparatus of the invention that is basically comprised of a shroud  25  having a terminal container  26 , a terminal container top  28 , a circuitry compartment  30 , a protector cover  31  for the circuitry compartment  30 , and a clamp  32  for the protector cover  31 . The shroud  25  is made from a high temperature, insulating plastic and is formed with a “U”-shaped cross section. The “U”-shaped cross section of the shroud  25  consists of an outer diameter surface shown as the outer wall  36  and inner diameter surface shown as the inner wall  38 . The outer wall  36  and the inner wall  38  are connected via an annular end wall  40 . The inner wall  38 , outer wall  36 , and end wall  40  are molded as an integral piece, and the interior surface of the shroud&#39;s “U”-shaped cross section forms an annular channel  42 . This annular channel houses the winding leads  24  and end turns  16  shown in FIG. 1. In FIG. 4, the shroud  25  is shown installed on the stator assembly  22  of FIG. 1 with the winding leads  24  and end turns  16  fully contained within the annular channel  42  formed by the interior of the “U”-shaped cross section of the shroud.  
         [0024]    In FIGS. 2 and 3, the shroud  25  has a plurality of arcuate slots  44  in the end wall  40 . The arcuate slots are radially centered on the end wall and circumferentially spaced in such a manner to provide structural integrity to the shroud  25 . The regular pattern of circumferential spacing of the arcuate slots  44  is interrupted in areas adjacent to the circuitry compartment  30  and the terminal container  26 . The slots provide the exterior surface of the end wall  40  with communication to the interior of the annular channel  42 . These arcuate slots  44  provide cooling paths from the end shields of the motor to the stator assembly  22 .  
         [0025]    In FIGS. 2 and 3, the inner wall  38  of the shroud  25  is shown with axial slots  46  through the inner wall  38  and partially through the end wall  40 . The axial slots  46  are circumferentially spaced about the inner wall  38 , providing communication between both the exterior surfaces of the inner wall  38  and end wall  40 , and the annular channel  42 . These inner wall axial slots  46  provide additional cooling paths from the end shields of the motor to the stator assembly  22 . The circumferential spacing of the axial slots  46  is interrupted in areas adjacent to the circuitry compartment  30  and the terminal container  26  to maintain structural integrity of the shroud  25  in these areas.  
         [0026]    In FIGS. 2 and 3, the outer wall  36  of the shroud  25  is shown with axial slots  48  through the outer wall  36  and partially through the end wall  40 . The axial slots  48  are circumferentially spaced about the outer wall  36 , providing communication between both the exterior surfaces of the outer wall  36  and end wall  40 , and the annular channel  42 . These outer wall axial slots  48  provide additional cooling paths from the end shields of the motor to the stator assembly  22 . The circumferential spacing of the axial slots  48  is interrupted in areas adjacent to the circuitry compartment  30  and the terminal container  26  to maintain structural integrity of the shroud  25  in these areas.  
         [0027]    [0027]FIGS. 2, 3, and  4  show the terminal container  26  integrally molded with the shroud  25 . The terminal container  26  is dimensioned to project radially outward from the shroud  25  to a position outside the housing  20  when the shroud  25  is positioned in the housing. In this configuration, the housing is provided with a notch  50  to accommodate the terminal container  26 . However, the terminal container  26  may be molded to project axially from the shroud. In that configuration, a notch  50  in the housing  20  need not be provided. Winding leads  24  are directed to the terminal container  26  to facilitate connection to an external apparatus of the motor. The terminal container  26  is rigged with a system of plug and socket quick-disconnects that provides a standard connection system to other components of the motor. As shown in FIG. 4, a single terminal container connector  52  can be used as a standard interface to an external motor apparatus. The terminal container arrangement enables the stator assembly  22  of the motor to be completed in manufacture without the need for winding leads  24  to be sized for a specific terminal point or fitted with a specific connector.  
         [0028]    In the shroud, in the area adjacent to the terminal container  26 , a terminal container arcuate slot  54  is provided in the end wall  40 . The terminal container arcuate slot  54  provides an opening for assembly operators to connect the winding leads  24  of FIG. 1 to the terminal points in the terminal container  26 . The terminal container  26  has a terminal container top  28 , which forms the external casing of the terminal container  26 . When removed, the terminal container top  28  exposes the inside of the terminal container and ports to which winding leads  24  of FIG. 1 can be connected. With the terminal container top  28  removed, assembly operators can connect winding leads to the terminals without a need to color code the ends of winding leads, and without the need to ensure the winding leads have sufficient length to connect to external motor apparatus. After connections are made to the required port inside the terminal container  26 , the terminal container top  28  snaps into place to form the external surface of the terminal container  26 . The terminal container top  28  can be removed to expose terminal connections and their ports for later testing and inspection without damaging winding leads or the protective sealant affixed thereon.  
         [0029]    The circuitry compartment  30  is molded into the shroud  25  as a rectangular slot in the end wall  40 . Positioned above the circuitry compartment  30  is a protector cover  31 . The protector cover is a resilient member that has an “L”-shaped cross-section as seen in FIG. 2. The “L”-shaped cross section permits the protector cover  31  to span over the circuitry compartment  30  in a radial direction across the end wall  40 . With the protector cover  31  having a “L”-shaped cross section, the portion of the cover that spans over the circuitry compartment  30  can be resiliently flexed away from the circuitry compartment a short distance to permit insertion of the protective temperature and current limiting devices in the circuitry compartment. The protector cover  30  is firmly attached to the shroud  25  at the interface of the inner wall  38  and the end wall  40  so as to form an integral unit with the shroud  25 . At the interface of the outer wall  36  and the end wall  40 , the edge of the protector cover  31  is suspended above the end wall and the circuitry compartment  30 . The edge of the protector cover  31  is provided with a lip  56  that engages a side of the protector device  58  and holds it in place. As a rectangular slot in the end wall  40 , the circuitry compartment  30  provides communication between the exterior surface of the end wall  40  and the annular channel  42 .  
         [0030]    As shown in FIG. 4, the circuitry compartment  30  and protector cover  31  serve as a storage location for standard protective temperature and current sensing devices  58 . Depending on the particular device intended to be used with the stator, the shape and size of the circuitry compartment would change to accommodate the device. Recessed shoulders  60  are formed inside the circuitry compartment at circumferentially opposite ends of the circuitry compartment. The recessed shoulders  60  provide seating surfaces for the temperature and current sensing devices  58 . With this arrangement, the device  58  is held in place inside the circuitry compartment  30  and on top of the recessed shoulders  60  by the protector cover  31 , while the opening between the recessed shoulders  60  of the circuitry compartment  30  provides a passage for directing the leads or other types of connections of the temperature and current sensing device  58  into the annular channel  42  and to the windings of the stator. The device  58  can be installed in the shroud  25  by lifting up the protector cover  31  and placing the device in the circuitry compartment  30 . Preferably, the device is held in place in the circuitry compartment by the resiliency of the protector cover.  
         [0031]    To ensure the positive location of the contents of the circuitry compartment  30 , a clamp  32  is used to hold down the suspended edge of the protector cover  31 . The clamp  32  is configured in a general “U”-shape and is fully detachable from the shroud  25 . The clamp  32  has a hook  62  on one end used to anchor the clamp to the shroud at the exposed edge of the inner wall  38 . On the other end, the clamp  32  is configured with a series of barbs  64  that enable the clamp to be anchored to the exposed edge of the outer wall  36 .  
         [0032]    In FIGS. 2 and 3, a plurality of stator slot posts  66  are shown projecting axially away from the shroud  25 . The posts are integral with the shroud and connected at the exposed edge of the inner wall  38 . The stator slot posts  66  are circumferentially spaced so as to engage inside several of the slots between the stator poles on the stator assembly  22 . The length of the stator slot posts  66  is determined to provide radial support and alignment of the shroud  25  with the stator assembly  22 . The radial thickness of the stator slot posts is set so as not to interfere with the stator bore or the annular channel  42 .  
         [0033]    While the present invention has been described by reference to a specific embodiment, it should be understood that modifications and variations of the invention may be constructed without departing from the scope of the invention defined in the following claims.