Abstract:
An electric motor endshield includes a plate and a capacitor-mounting assembly particularly suitable for secure attachment to a capacitor. The mounting assembly includes a lug presenting a capacitor-engaging projection spaced outwardly from the endshield plate. The capacitor-engaging projection presents an inner face in an opposed relationship to the endshield plate to define a capacitor-retaining space therebetween. A peripheral lip of the capacitor housing is received within the capacitor-retaining space, and the housing lip engages the capacitor-engaging projection. The mounting assembly provides secure attachment of the capacitor to the endshield, thereby preventing inadvertent detachment of the capacitor during operation of motor.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention is broadly concerned with electric motors. More particularly, the present invention concerns a motor with an endshield permitting secure attachment of components, such as a run capacitor. Yet further, the invention is directed to an endshield which includes mounting structure specifically suitable in securing a modern-day, short-length capacitor to the endshield. 
         [0003]    2. Description of the Prior Art 
         [0004]    Small electric motors of the type used in household appliances and for powering pool or spa pumps generally include a rotor and stator windings received within a generally tubular motor housing. The ends of the housing are capped by endshields. In one class of these motors, a mounting endshield is provided at one end of the motor housing, with a component-supporting endshield at the opposite end of the housing. The latter may for example support a run capacitor which is energized while the motor is running and increases the efficiency of the motor. It is of course very important that such a capacitor be securely attached to the associated endshield, else motor vibrations and the like will cause the capacitor to separate from the endshield, leading to premature motor failure. 
         [0005]      FIGS. 1-4  illustrate one type of prior art motor endshield used for supporting a conventional run capacitor. Referring to these figures, it will be observed that the motor housing endshield  20  is of generally circular configuration and has a mounting assembly  22  for a relatively long capacitor  24 . As is common, the capacitor  24  has a tubular housing  26  with a peripheral lip  28 . A pair of circuit connectors  30  extend outwardly from the end wall  32  of housing  26 . 
         [0006]    The capacitor mounting assembly  22  includes a pair of spaced apart cradles  34  and  36 . Each of the cradles  34  and  36  has an arcuate surface  34   a  and  36   a,  respectively, which is complementally shaped and dimensioned with the capacitor housing  26 . A secondary support segment  38  is also provided between the cradles  34  and  36 , and similarly has an arcuate surface  38   a  complemental with the capacitor housing  26 . An upright, internally threaded stanchion  40  is positioned adjacent the support segment  38 . Finally, an outwardly extending abutment  42  is positioned proximal to the cradle  34 , as best seen in  FIGS. 1 and 2 . 
         [0007]    The capacitor  24  is mounted on the endshield  20  by positioning the housing  26  on the cradles  34  and  36  and segment  38 , followed by axially shifting the capacitor  24  until the lip  28  comes into contact with the abutment  42 . At this point, an arcuate connection strap  44  is positioned over the housing  26  and a screw  46  is used to attach the end of the strap  44  to the stanchion  40 . 
         [0008]    It will be observed that the abutment  42  of mounting assembly  22  provides no capacitor restraint or locking function, but rather serves merely to assist in positioning the capacitor  22  on the endshield  20 . The strap  44  serves as the only means of securing the capacitor in place on the endshield  20 . 
         [0009]    Recently, capacitor manufacturers have been able to reduce the length of motor run capacitors, as compared with the capacitor illustrated in  FIGS. 1-4 . However, existing mounting assemblies forming a part of motor endshields cannot properly accommodate these lesser length capacitors, and hence the capacitors cannot be secured to the existing endshields of  FIGS. 1-4  with the necessary degree of structural integrity. 
         [0010]    Accordingly, there is a need in the art for improved endshield capacitor mounting assemblies which can accept modern-day, shorter length capacitors, and secure these to endshields against vibrations and other forces tending to dislodge the capacitors. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention overcomes the problems outlined above and provides electric motor endshields, endshields in combination with short-length capacitors, and electric motors including the endshields and capacitors. 
         [0012]    According to a first aspect of the present invention, an electric motor assembly includes a rotor rotatable about an axis and a stator spaced radially from the rotor. The motor assembly further includes a case defining an internal motor chamber in which the stator and rotor are housed, with the case presenting axial margins. The case includes an endshield adjacent one of the axial margins. The endshield includes a plate with a capacitor-mounting assembly thereon. The capacitor-mounting assembly includes a lug presenting a capacitor-engaging projection spaced outwardly from the endshield plate. The capacitor-engaging projection presents an inner face in an opposed relationship to the endshield plate to define a capacitor-retaining space therebetween. The motor assembly further comprises a capacitor including a housing with a peripheral lip. The housing lip is located within the capacitor-retaining space, with the housing lip engaging the capacitor-engaging projection. 
         [0013]    The present invention similarly concerns the combination of an endshield to be positioned adjacent an axial margin of a motor case and a capacitor mounted on the endshield. 
         [0014]    The endshield includes a plate with a capacitor-mounting assembly thereon. The capacitor-mounting assembly includes a lug presenting a capacitor-engaging projection spaced outwardly from the endshield plate. The capacitor-engaging projection presents an inner face in an opposed relationship to the endshield plate to define a capacitor-retaining space therebetween. The capacitor includes a housing with a peripheral lip. The housing lip is located within the capacitor-retaining space, with the housing lip engaging the capacitor-engaging projection. 
         [0015]    In yet a further aspect of the present invention, an electric motor endshield is configured to be positioned adjacent an axial margin of a motor case and is operable to support a capacitor thereon. The endshield comprises a plate with a capacitor-mounting assembly thereon. The capacitor-mounting assembly includes a lug presenting a capacitor-engaging projection spaced outwardly from the endshield plate. The capacitor-engaging projection presents an inner face in an opposed relationship to the endshield plate to define a capacitor-retaining space therebetween. The capacitor-retaining space is configured to receive the housing lip of a capacitor, with the capacitor-engaging projection engaging the housing lip. 
         [0016]    The endshield mounting assembly is particularly well-suited to support a short-length capacitor having the peripheral lip at an end of the housing. In preferred forms, the capacitor mounting assembly includes a pair of capacitor-supporting segments adjacent and on opposite sides of the lug, as well as a support segment spaced from the lug. Each of the lugs preferably has a support surface complemental with the capacitor housing. In use, the housing wall is placed on the support segments and shifted so that the lip is received within the space between the lug projection and endshield plate. A clamping strap is then placed over the capacitor sidewall and attached to the endshield plate, firmly securing the capacitor to the endshield. 
         [0017]    This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description of the preferred embodiments. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. 
         [0018]    Various other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments and the accompanying drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0019]    A preferred embodiment of the present invention is described in detail below with reference to the attached drawing figures, wherein: 
           [0020]      FIG. 1  is an exploded perspective view of a prior art motor endshield and capacitor; 
           [0021]      FIG. 2  is a perspective view similar to that of  FIG. 1 , but depicting the run capacitor installed on the prior art endshield; 
           [0022]      FIG. 3  is an elevational view of the prior art assembly illustrated in  FIG. 2 ; 
           [0023]      FIG. 4  is a sectional view taken along the line  4 - 4  of  FIG. 3 ; 
           [0024]      FIG. 5  is a perspective view of an electric motor including an endshield constructed in accordance with a preferred embodiment of the present invention, wherein the endshield is installed adjacent one end of the motor case, with a short-length capacitor secured to the endshield; 
           [0025]      FIG. 6  is an exploded perspective view of the endshield and capacitor depicted in  FIG. 5 ; 
           [0026]      FIG. 7  is a greatly enlarged, fragmentary perspective view depicting the capacitor connection lug assembly of the preferred endshield; 
           [0027]      FIG. 8  is an enlarged, fragmentary perspective view similar to that of  FIG. 7 , but depicting the side of the endshield opposite that of  FIG. 7 ; 
           [0028]      FIG. 9  is an elevational view of the preferred endshield and capacitor assembly; and 
           [0029]      FIG. 10  is a sectional view taken along line  10 - 10  of  FIG. 9 . 
       
    
    
       [0030]    The drawing figures do not limit the present invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the preferred embodiments. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0031]    The present invention is susceptible of embodiment in many different forms. While the drawings illustrate, and the specification describes, certain preferred embodiments of the invention, it is to be understood that such disclosure is by way of example only. There is no intent to limit the principles of the present invention to the particular disclosed embodiments. 
         [0032]    Turning now to the drawings, an overall electric motor  48  in accordance with a preferred embodiment of the present invention is illustrated in  FIG. 5 . The motor  48  broadly includes a motor case  50  receiving the usual rotor/stator motor mechanism  52  therein. In the illustrated embodiment, one end of the case  50  is equipped with a metallic plate-like mounting endshield  54  equipped with corner mounting apertures  56  allowing the entire motor  48  to be secured within a machine or the like. The other end of case  50  has a component-supporting endshield  58 . The endshield  58  is also preferably made of metal and, in the illustrated embodiment, is particularly designed to support a capacitor  60 . Although the illustrated capacitor  60  is depicted as a modern, short-length motor run capacitor, it will be understood that the principles of the present invention are not necessarily limited to such a component (e.g., it is within the ambit of the present invention to mount an alternative capacitor on the endshield  58 ). Although not shown, it will be appreciated that endshield  58  and capacitor  60  may be covered by a removable end cap, which may be of the general type illustrated in U.S. Pat. No. 5,278,469. 
         [0033]    The endshield  58  includes a central plate section  62  supporting a capacitor-mounting assembly  64 . The preferred mounting assembly  64  includes an outwardly extending support segment  70  having an arcuate support surface  72 . In addition, the mounting assembly  64  has a lug  74  (see  FIGS. 7 and 8 ) spaced from the segment  70 . In the illustrated embodiment, the lug  74  has an inverted, generally L-shaped configuration, although other lug shapes and dimensions are within the scope of the present invention, as will be subsequently described. The illustrated lug  74  includes a leg  76  extending outwardly from plate section  62  and a transversely extending, capacitor-engaging projection  78  spaced from the section  62 . The projection  78  has a pair of opposed side edges  80  and  82 , between which an inner surface  78   a  of the projection  78  is defined. A capacitor-retaining space  84  is thus defined between the inner surface  78   a  and the plate section  62 . Again, the shape and configuration of the lug  74  may be altered without departing from the scope of the present invention, as long as the lug  74  presents the inner surface  78   a  spaced from the plate section  62  so as to define the capacitor-retaining space  84 . For example, the leg  76  may alternatively extend obliquely from the plate section  62  or be replaced entirely with alternative structure that spaces the inner surface  78   a  from the plate section  62 . Furthermore, the inner surface  78   a  may also be alternatively configured without departing from the spirit of the present invention. For example, it is not necessary for the inner surface  78   a  to have the generally rectangular, flat configuration that is generally parallel to the plate section  62 , as depicted in the preferred embodiment. For example, if desired, the inner surface  78   a  could be provided with corrugations, angled relative to the plate section  62 , be non-polygonal in shape, etc. 
         [0034]    The illustrated endshield  58  is preferably formed of a casting process. More preferably, the endshield  58  is cast of metal and, most preferably, of aluminum. However, the endshield may alternatively be formed of other suitable techniques (e.g., stamped) and materials (e.g., non-metals, such as synthetic or composite materials). Inasmuch as the illustrated lug  74  is formed by a casting procedure, an opening  86  is preferably formed in the plate section  60  immediately adjacent the lug. A pair of outwardly extending support segments  88  and  90  are provided on opposite sides of the opening  86  and in close adjacency to lug  74 . In order to complement the shape of the illustrated capacitor  60 , the segments  88  and  90  preferably have outer arcuate support surfaces  92  and  94 , respectively. The overall mounting assembly  64  also includes an upstanding, internally threaded stanchion  96  spaced from lug  74 . An arcuate clamping strap  98  is preferably secured to the stanchion by an attachment screw  100 . With the stanchion  96 , and therefore the strap  98 , being spaced from the lug  74 , the capacitor is preferably clamped at a point spaced from the lug  74 . And in the case of the illustrated modern, short-length capacitor  60 , it is clamped adjacent the end opposite the lug  74 . 
         [0035]    It is noted that the endshield  58  is also provided with a cradle  101  that is spaced further from the lug  74  than the segment  70 . Those of ordinary skill in the art will appreciate that the cradle  101  permits the endshield  58  to also be used with the more traditional capacitor  24 , as depicted in  FIGS. 1-4 . 
         [0036]    The relatively short, run capacitor  60  has a substantially cylindrical sidewall  104  and an end plate  106 . Projecting axially beyond the end plate  106  is a peripheral lip  108 . That is, the end plate  106  is slightly recessed, with the lip  108  providing a circumferential, axial projection. If desired, the lip  108  may have alternative forms without departing from the spirit of the present invention (e.g., the lip  108  need not extend continuously about the circumference of the capacitor, the sidewall and lip need not be circular in cross-sectional shape, etc.). The capacitor  60  also has conventional, internal capacitive components  109  and outwardly projecting circuit connectors  110 , as shown in  FIG. 10 . 
         [0037]    In order to mount the capacitor  60  to the endshield  58 , the capacitor  60  is placed on segments  70 ,  88 , and  90 , with the respective support surfaces  72 ,  92 , and  94  complementally mating with the capacitor sidewall  104 . It is noted that if the capacitor  60  is provided with an alternatively shaped and/or dimensioned sidewall, the surfaces  72 ,  92 , and  94  are appropriately modified to complement the alternative design. Because the illustrated lip  108  also projects somewhat radially relative to the sidewall  104 , the capacitor  60  may need to be oriented and moved at a slight angle relative to the endshield  58  so that the lip can be positioned both under the inner surface  78   a  (within the capacitor-retaining space  84 ) and the sidewall onto the support surfaces  72 ,  92 , and  94 . Once the capacitor  60  is resting on the surfaces  72 ,  92 , and  94 , the capacitor  60  is preferably shifted axially so that the lip  108  is moved into engagement with the leg  76  (see,  FIG. 10 ). Next, the clamping strap  98  is positioned in overlying relationship to the housing  104  and is secured to stanchion  96  by screw  100 . 
         [0038]    In this regard, when the capacitor  60  is secured to the endshield  58 , the peripheral lip  108  comes into bearing contact with the side edges  80  and  82  of the projection  78 . Because the illustrated lip  108  is circular in shape, while the inner surface  78   a  is flat, the portion of the lip  108  between the side edges  80  and  82  extends within the space  84  but does not contact the inner surface of the projection  78 . If desired, however, the inner surface  78   a  and lip  108  may alternatively be designed to have a complemental shape (e.g., the inner surface may alternatively have an arcuate shape with the same radius of curvature as the peripheral lip  108 ) so that the surface  78   a  and lip  108  continuously engage one another between the side edges. Returning to the illustrated embodiment, the lug  74  provides essentially tangential point contact with the lip  108  at spaced locations thereon. It has been found that this type of point contact, together with the compressive force generated by the clamping strap  98 , serves to firmly secure the capacitor  60  in place on the endshield  58  against all normal vibrations and shocks attendant to operation of motor  48 . 
         [0039]    While the invention has been described in the context of mounting a run capacitor on an electric motor endshield, it will be appreciated that the mounting assembly hereof could also be used for the support of a start capacitor, if desired. 
         [0040]    The preferred forms of the invention described above are to be used as illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention. 
         [0041]    The inventor hereby states his intent to rely on the Doctrine of Equivalents to determine and access the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention set forth in the following claims.