Abstract:
An alternator assembly powered by a pulley is made up of an outer housing that contains the stator and rotor assemblies, an inner housing and a rear cover which is retained by a fastening member that secures the inner housing and rear cover within the outer housing.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to an alternator, more particularly, the present invention is related to a housing for a motor vehicle alternator.  
         DESCRIPTION OF PRIOR ART  
         [0002]    Alternators are used in many modern-day industries to convert mechanical power to electrical power within an engine. In the motor vehicle industry, in particular, alternators have become a staple item. Alternators are now used in virtually every automobile produced. This translates into a large overall production cost for automotive manufacturers and automotive parts manufacturers.  
           [0003]    Furthermore, the technology boom of the last couple decades has had a significant impact on the automotive industry. As customers demand more gadgets and feedback on their vehicle performance, automobiles now contain a dramatically increased number of electronic devices. This trend has increased the electrical output demanded of the alternators used within the automobiles and has increased their size. With an increased number of components to be packaged and a larger alternator required to power them, the always tight packaging space in a vehicle has become even more of an issue.  
           [0004]    The housing unit is a large component of an alternator unit. Modern alternators generally include a housing comprised of at least two housing pieces. One function of this configuration is to contain the inner components of the alternator. The most common way of attaching the two housing pieces is by using a plurality of thru-bolts and nuts. In this configuration, the thru-bolts are inserted through cavities disposed in the two housing pieces and then threaded into cavities disposed in the other housing, thereby creating a rigid outer housing that retains and protects the internal components of the alternator.  
           [0005]    As a result of the well-known method and apparatus discussed above, the cost-efficiency as well as the space-efficiency of contemporary alternators is not optimized. More specifically, the use of thru bolts adds unnecessary weight to the assembly and consumes excessive space within and around the assembly. Furthermore, the space consumed by the thru-bolt and nut combination frequently interferes with the placement of other engine components.  
           [0006]    Therefore, there is a need in the automotive industry, as well as in other industries, for a smaller and improved housing assembly for retaining and protecting the internal components of an alternator.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    In accordance with the present invention, a housing means is provided to retain the internal components of an alternator without the use of thru-bolts to hold the front and rear housing together. An inner and outer housing is used where an internal thread is cut into the top of the outer alternator housing. The internal thread is capable of receiving an externally threaded packing nut. When the packing nut is tightened the inner housing is seated on a machined surface on the outer housing. The packing nut is tightened with a device such as a spanner wrench.  
           [0008]    The packing nut and housing combination replaces the commonly used thru-bolts, which require a boss on the exterior of the alternator and increase the packaging space in the vehicle required for the alternator.  
           [0009]    The packing nut retention of the can may be improved by a number of methods. An anaerobic locking compound can be added to the external threads on the packing nut prior to installation to improve retention. An mechanical crimp of the exterior of the outer housing can be made locking the outer housing to the fastener also to improve retention.  
           [0010]    Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a side view of a section through the alternator assembly of the present invention;  
         [0012]    [0012]FIG. 2 is a side view of a section through a prior art design of an alternator assembly; and  
         [0013]    [0013]FIG. 3 is a side view of an enlarged section through the alternator assembly of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0014]    The foregoing discussion discloses and describes the preferred embodiment of the invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that changes and modifications can be made to the invention without departing from the true spirit and fair scope of the invention as defined in the following claims. The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.  
         [0015]    Referring now to FIG. 1, an alternator assembly  10  is shown. The alternator assembly  10  includes a rotor  12  that is attached to a pulley  16  by a shaft  36  rotatably mounted within the assembly  10  on bearings  11 . As the vehicle engine runs a belt (not shown) coupled to the pulley  16  causes rotation of the pulley  16  and therefore the rotor  12 . Rotation of the rotor  12  producing a magnetic field in the rotor  12 . The rotor  12  is surrounded by a stator  14  that includes a set of coils and an iron core  18 . The stator  14  is stationary in the alternator assembly  10 . As the magnetic field from the rotor  12  sweeps through the stator  14 , it produces electrical current for use in the vehicle. Enclosing the coils at the stator  14  by an inner housing or stator cover  18 . The stator core  18  is in turn enclosed by and is fixed, possibly by a press fit, to a rear inner housing  21 . Rear inner housing  21  fits inside an outer housing  20 .  
         [0016]    The outer housing  20  is generally cylindrical in shape and is composed of sides  22  and  24 , a closed end  26  and an open end  28 . The closed end  26  is open near its middle and shaft  36  extends therethrough locating the pulley  16  outside the housing  20 . On the open end  28  of the outer housing  20  are internal threads  30  and inboard of the internal threads  30  is a machined shoulder  32 . The shoulder  32  operates as a seat where flange  33  of the rear inner housing  21  is received. The rear cover  34  is a generally fiat component with a flat surface  40  with stepped flange  38  that is bent downward then extend outward from the flat surface  40 . The stepped flange  38  sit atop the flange  33  and the rear inner housing  21 . The rear cover  34  encloses the open end  28  of the outer housing  20 .  
         [0017]    The rotor  12  and stator  14  and all other internal components of the alternator assembly  10  are thus enclosed within the outer housing  20 .  
         [0018]    Retaining rear cover  34  and inner housing  21  within outer housing  20  is a packing nut  42 . The packing nut  42  is generally a ring shape and fits atop the stepped flange  38  of the rear cover  34 . The packing nut  42  is provided with external threads  44  that matingly engage the internal threads  30  of the outer housing  20 .  
         [0019]    Now referring to FIG. 2, the alternator assembly  110  of the prior art is shown. The internal components of the alternator assembly  110  are surrounded by an outboard housing  112  and an inboard housing  114 . Outboard housing  112  is generally cylindrical in shape and consists of a closed end  120 , and an open end  126 . Inboard housing  114  is also generally cylindrical in shape and consists of a closed end  124  and open end  128 . Outboard housing  112  meets inboard housing  114  at open end  126  and open end  128 , respectively.  
         [0020]    Housing  112  also contains bosses  130  and  132  on the outer edges of top  120 . Thru bolts  116  and  117  fit into bosses  130  and  132 . Thru bolts  116  and  117  contain threaded portions  136  and  138  at their ends, respectively. Thru bolts  116  and  117  fit through top housing  112  at thru holes  140  and  142  threaded end portions  136  and  138  of thru bolts  116  and  117 , respectively, engage threaded bores  144  and  146  of inboard housing  114 . The upper housing  112  and lower housing  114  are thus fastened together, thus securing the internal components of the alternator assembly  10 .  
         [0021]    Referring to FIG. 3, the alternator assembly  10  is shown after the installation of the packing nut  42  in a close-up sectional view. The stator core  18  is positioned within rear inner housing  21 . The rear cover  34  sits atop the rear inner housing  21 . The packing nut  42  secures the rear cover  34  as well as the rear inner housing  21  and the stator assembly  14  to the outer housing  20 .  
         [0022]    The packing nut  42  preferably includes multiple spanner slots  60  such that a spanner wrench may engage the spanner slots  60  to rotate or tighten packing nut  42 . As a result of being tightened, external threads  44  are in contact with the internal threads  30  of outer housing  20  and rotor  12  and stator  14  are secured within the outer housing  20 , rear inner housing  21  and rear cover  34 .  
         [0023]    A retaining compound may be applied between external threads  44  and internal threads  30 . The retaining compound is preferably a liquid that is applied to one or both of external threads  44  and internal threads  30  before packing nut  42  is tightened. The retaining compound functions to prevent movement of packing nut  42  and outer housing  20  relative to one another. Multiple suitable retaining compounds will be known to persons of ordinary skill in the art.  
         [0024]    As an alternative to the retaining compound, a mechanical stake may be used to secure packing nut  42  and outer housing  20 . For example, once packing nut  34  has been tightened, external threads  44  and internal threads  30  may be deformed in corresponding locations to prevent relative rotation between packing nut  42  and outer housing  20 . Alternatively, other suitable methods of forming a mechanical stake known to persons of ordinary skill in the art may be used.  
         [0025]    While the above description constitutes the preferred embodiments of the present invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope and fair meaning of the accompanying claims.