Abstract:
A generator assembly ( 6 ) includes a crankshaft ( 10 ), an accessory pulley drive shaft ( 36 ) operatively coupled to the crankshaft ( 10 ), and a flexible drive coupling member ( 40 ) operatively coupling the accessory pulley drive shaft ( 36 ) and the crankshaft ( 10 ). The flexible drive coupling member ( 40 ) includes a plurality of flex drive rings ( 64 - 66 ) that are configured to transmit torque from the crankshaft ( 10 ) to the accessory pulley drive shaft ( 36 ) with substantially no torsional deflection while allowing the accessory pulley drive shaft ( 36 ) to deflect radially under radial load and deflect axially under axial load in order to accommodate misalignment of the accessory pulley drive shaft ( 36 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to the art of electrical generators and, more particularly, to a flexible drive coupling for an electrical generator. 
         [0002]    Many modern vehicles utilize electronic and other devices that possess large power demands. Commercial vehicles, such as semi-trailers, now include both computer and entertainment systems. Military vehicles include computer equipment as well as radars, communication equipment and weapon systems all of which possess high energy demands. In order to meet these increasing energy demands, many vehicles now include generator systems configured for use in conjunction with low speed reciprocating engines. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0003]    According to one aspect of the invention, a generator assembly includes a rotor, an accessory pulley drive shaft operatively coupled to the rotor, and a flexible drive coupling member operatively coupling the accessory pulley drive shaft and the rotor. The flexible drive coupling member includes a plurality of flex drive rings that are configured to transmit torque from the rotor to the accessory pulley drive shaft with substantially no torsional deflection while allowing the accessory pulley drive shaft to deflect radially under radial load and deflect axially under axial load in order to accommodate misalignment of the accessory pulley drive shaft. 
         [0004]    According to another aspect of the invention, a generator system includes an engine including a crankshaft, a rotor operatively coupled to the crankshaft, an accessory pulley drive shaft operatively coupled to the rotor, and a flexible drive coupling member operatively coupling the accessory pulley drive shaft and the rotor. The flexible drive coupling member includes a plurality of flex drive rings that are configured to transmit torque from the rotor to the accessory pulley drive shaft with substantially no torsional deflection while allowing the accessory pulley drive shaft to deflect radially under radial load and deflect axially under axial load in order to accommodate misalignment of the accessory pulley drive shaft relative to the crankshaft. 
         [0005]    According to yet another aspect of the exemplary embodiment, a flexible drive coupling member includes a plurality of flex drive rings. Each of the plurality of flex drive rings includes a main body having central opening and an outer edge portion. Adjacent ones of the plurality of flex drive rings are joined to form a resilient connection for transmitting torque from a driving member to a driven member with substantially no torsional deflection while allowing the driven member to deflect radially under radial load and deflect axially under axial load in order to accommodate misalignment of the driven member and the drive member. 
         [0006]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0007]    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: 
           [0008]      FIG. 1  is a cross-sectional perspective view of a motor generator assembly including a motor portion and a generator assembly in accordance with an exemplary embodiment; 
           [0009]      FIG. 2  is a cross-sectional elevational view of the generator assembly of the motor generator of  FIG. 1 ; 
           [0010]      FIG. 3  is a lower right perspective view of a flexible drive coupling member of the generator assembly of  FIG. 2  in accordance with an exemplary embodiment; 
           [0011]      FIG. 4  is a cross-sectional elevational view of the flexible drive coupling member of  FIG. 3 ; 
           [0012]      FIG. 5  is a cross-sectional elevational view of a generator assembly including a flexible drive member in accordance with another exemplary embodiment; 
           [0013]      FIG. 6  is a lower right perspective view of a flexible drive coupling member of the generator assembly of  FIG. 5  in accordance with an exemplary embodiment; and 
           [0014]      FIG. 7  is a cross-sectional elevational view of the flexible drive coupling member of  FIG. 6 . 
       
    
    
       [0015]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    With reference to  FIGS. 1 and 2 , a generator system shown in the form or a motor generator constructed in accordance with an exemplary embodiment is indicated generally at  2 . Motor generator  2  includes a motor portion  4  and a generator assembly  6 . Motor portion  4  takes the form of an internal combustion engine including a plurality of pistons (not shown) operatively connected to a driving member or crankshaft  10 . Motor portion  4  is also shown to include a plurality of accessory pulleys of  12  and  13  as well as an idler pulley  15  and a fan  16 . In further accordance with the exemplary embodiment shown, generator assembly  6  includes a housing  21  within which is positioned a rotor  24  and a stator  27  that includes a plurality or warnings (not shown). Generator assembly  6  includes a first accessory pulley  30  and a second accessory pulley  32 . Accessory pulley  32  is operatively connected to crankshaft  10  through a driven member or accessory pulley draft shaft  36  by a plurality of mechanical fasteners, one of which is indicated as  38 . Accessory pulley draft shaft  36  is operatively connected to crankshaft  10  via a flexible drive coupling member  40 . Flexible drive coupling member  40  allows for alignment variations between accessory pulley draft shaft  36  and crankshaft  10  in a manner that will be discussed more fully below. 
         [0017]    As best shown in  FIGS. 3 and 4 , flexible drive coupling member  40  includes a base plate  46  having a plurality of openings, one of which is indicated at  58 , for receiving mechanical fasteners  60  ( FIG. 2 ) that retain flexible drive coupling member  40  to crankshaft  10 . Flexible drive coupling member  40  is also shown to include a plurality of flex drive rings  64 - 66  which, as will be discussed more fully below, provide axial flexation about multiple axes in order to accommodate any misalignments between accessory pulley drive shaft  36  and crankshaft  10 . In addition, to flex drive rings  64 - 66 , flexible drive coupling member  40  includes a flexible drive ring that takes the form of a shaft attachment plate  68 . Shaft attachment plate  68  includes a main body portion  69  provided with a central hub  72  that includes a splined portion  75 . Splined portion  75  is configured to receive a corresponding splined portion (not shown) of accessory pulley drive shaft  36 . Of course it should be understood that central hub  72  can be joined to accessory pulley drive shaft  36  using a key, bolts, a press fit or the like. As each flex drive rings  64 - 66  is similarly formed, a detailed description will follow with respect to flex drive ring  64 , with an understanding that the remaining flex drive rings, i.e., flex drive rings  65  and  66 , include corresponding structure. 
         [0018]    As shown, flex drive ring  64  includes a main body  82  having a central opening  85  and an outer edge portion  87 . A pair of connection zones  91  and  92  are arranged on main body  82  between central openings  85  and  87 . Flex drive ring  64  also includes a second pair of connecting zones, namely connecting zone  94  and an opposing connecting zone (not shown) that are off-set 90 degrees from connecting zones  91  and  92 . With this arrangement, connecting zones  91  and  92  connect flex drive ring  64  to base plate  56  while connecting zone  93  and opposing connecting zone (not shown) couple flex drive ring  64  to adjacent flex drive ring  65 . In a similar manner, coupling is achieved between flex drive ring  65  and flex drive ring  66 , and between flex drive ring  66  and shaft attachment plate  68 . 
         [0019]    With this arrangement, multiple flex drive rings, connected at 90 degree intervals, allow shaft attachment plate  68  to radially deflect under radial load, and axially deflect under axial load. This is, flex drive rings  64 - 66  and shaft attachment plate  68  act as springs in the axial direction. In addition, by keeping stress below an infinite life stress strain curve for a particular material flex drive rings  64 - 66  and shaft attachment plate  68  are able to accommodate both axial and radial shaft misalignment without incurring wear. In any event, in the exemplary embodiment shown, flex drive rings  64 - 66  and shaft attachment plate  68  are joined at connector zones  91 - 93  through the use of mechanical fasteners such as indicated at  100 - 103  in  FIG. 4 . 
         [0020]    Reference will now be made to  FIGS. 5-7 , wherein like reference numerals represent corresponding parts in the respective views, in describing a flexible drive coupling member  140  constructed in accordance with another exemplary embodiment. As shown, flexible drive coupling member  140  includes a base plate  156  having a plurality of openings  158  for receiving mechanical fasteners, such as indicated at  160  in  FIG. 5 . Mechanical fastener  160  secures base plate  156  to crankshaft  10 . Flexible drive coupling member  140  is also shown to include a plurality of flex drive rings  164 - 167  as well as an additional flex drive ring that takes the form of a shaft attachment plate  168 . Shaft attachment plate  168  includes a main body portion  169  having a central hub  172  including a splined portion  175  that is configured to matingly receive corresponding splines on accessory pulley drive shaft  36 . Of course it should be understood that central hub  172  can be joined to accessory pulley drive shaft  36  using a keyed connection, bolts, a press fit, or the like. As each flex drive rings  164 - 167  is similarly formed, a detailed description will follow with regard to flex drive ring  164  with an understanding that the remaining flex drive rings  165 - 167  include similar structure. 
         [0021]    As shown, flex drive ring  164  includes a first flex member  182  and a second flex member  183 . First and second flex members  182  and  183  include corresponding inner edge portions  185 ,  186  that define central openings  188  and  189  respectively. In addition, first and second flex members  182  and  183  include outer edge portions  192  and  193  respectively. A flexible radial web  196  extends between inner edge  185  and outer edge  192  of first flex member. Similarly, a flexible radial web  197  extends between inner edge  186  and outer edge  193  of second flex member  183 . 
         [0022]    In accordance with the exemplary embodiment, first and second flex members  182  and  183  are secured one to the other at outer edges  192  and  193  through a mechanical joining process, such as welding. Inner edges  185  and  186  are secured to base plate  156  and adjacent flex drive ring  165  via flexible connecting members  203  and  204  respectively. With this arrangement, flexible drive coupling member  140  allows shaft attachment plate  168  to radially deflect under radial load and axially deflect under axial load. That is, each flex drive ring  164 - 167  and shaft attachment plate  168  act as springs. In a manner similar to that described above, by maintaining stress below an infinite like stress strain curve for a particular material, flex drive rings  164 - 167  and shaft attachment plate  168  are able to accommodate both radial and axial shaft misalignments without incurring wear. 
         [0023]    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.