Abstract:
A combination run capacitor/positive temperature coefficient resistor/overload (CAP/PTCR/OL) module is described. The cover of the combination housing includes a capacitor compartment and terminal openings for receiving blade terminals of a run capacitor. The terminal openings in the cover align with blade receiving receptacles coupled to the PTCR start circuit. The blade terminals of a run capacitor are inserted into the receptacle openings and into electrical engagement with the blade receiving receptacles. The capacitor is supported and protected by a potting mixture filling the capacitor compartment.

Description:
BACKGROUND OF INVENTION  
         [0001]    This invention relates generally to electric motors, and more particularly, to a motor starting device.  
           [0002]    At least some known electric motors include a start or auxiliary winding and a run winding. Either the start or run winding may be used to initiate rotation of a motor rotor. More specifically, when the start and run windings are energized, a geometric and time phase relationship between magnetic fields generated by the run and start windings, and the magnetization of the rotor, cause the rotor to begin rotating from a standstill condition. Once the rotor has sufficient torque to attain its normal running speed, the start winding is disconnected from the motor circuit.  
           [0003]    Start and run capacitors are sometimes used to change the time phase relationship between magnetic fields generated by the run and start or auxiliary windings. If a run capacitor is connected in series with the start winding, rather than disconnecting the start winding once sufficient rotor torque is attained, the start winding may be utilized as an auxiliary run winding after motor start-up. More specifically, an auxiliary run winding facilitates improving motor efficiency and power factor. A motor starting switch may be used to control energizing and de-energizing the motor start winding or start capacitor. At least some known motors include a positive temperature coefficient resistor/over load (PTCR/OL) used to perform this switching function.  
           [0004]    In at least some hermetic compressor applications, a separate PTCR/OL and run capacitor are externally mounted to the compressor housing. The PTCR/OL and capacitor are then electrically coupled to the motor circuit. Accordingly, the capacitor and PTCR/OL must be assembled separately, and as such manufacturing costs are increased. Additionally, over time, the electrical and mechanical connection between the PTCR/OL and capacitor may deteriorate when exposed to adverse conditions.  
         SUMMARY OF INVENTION  
         [0005]    In one aspect, a method of fabricating a run capacitor/positive temperature coefficient resistor/overload (CAP/PTCR/OL) assembly for an electric motor is provided. The method includes providing a base formed of electrically insulative material and including a surface and sidewalls extending from the surface to form a compartment, positioning a positive temperature coefficient resistor at least partially within the base compartment, positioning an overload at least partially within the base compartment, forming a cover from an electrically insulative material and including a first surface, an opposite second surface and a plurality of sidewalls extending from the first surface, the sidewalls are integrally formed with the first surface wherein the sidewalls extend from the first surface and form a compartment which is sized to at least partially receive a run capacitor, forming at least one aperture that extends through the cover internal to the compartment, and a plurality of projections that extend from the second surface, and coupling the cover to the base enclosing a plurality of components within the base compartment.  
           [0006]    In another aspect, a run capacitor/positive temperature coefficient resistor/overload (CAP/PTCR/OL) assembly is provided. The assembly includes a base formed of electrically insulative material and includes a first surface and a plurality of sidewalls extending therefrom to form a compartment with the first surface, a positive temperature coefficient resistor at least partially contained within the base compartment, an overload at least partially contained within the base compartment, and a cover formed of electrically insulative material, the cover coupled to the base enclosing the components within the base compartment and comprising a first surface, an opposite second surface and a plurality of sidewalls extending from the first surface and are integrally formed with the first surface, the sidewalls extend from the first surface and form a compartment sized to at least partially receive a run capacitor assembly therein, at least one aperture extending through the cover internal to the compartment, and a plurality of projections extending from the second surface.  
           [0007]    In yet another aspect, a run capacitor/positive temperature coefficient resistor/overload (CAP/PTCR/OL) assembly cover is provided. The cover is configured to couple to a PTCR/OL base. The cover includes a first surface, a plurality of sidewalls that extend from the first surface and are integrally formed with the first surface, the sidewalls extend from the first surface and form a compartment that is sized to at least partially receive a run capacitor assembly therein, at least one aperture extending through the cover internal to the compartment, a second surface, opposite to the first surface and a plurality of projections extending from the second surface.  
           [0008]    In another aspect, a run capacitor/positive temperature coefficient resistor/overload (CAP/PTCR/OL) assembly cover is provided. The cover is configured to couple to a PTCR/OL base. The cover includes a first surface, a plurality of sidewalls that extend from the first surface and are integrally formed with said first surface, the sidewalls extend from the first surface and form a platform that is sized to at least partially receive a run capacitor assembly thereon, at least one aperture extending through the platform, a second surface, opposite to the first surface and, a plurality of, projections extending from the second surface. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0009]    [0009]FIG. 1 is a cut away side view of a run capacitor/positive temperature coefficient resistor/overload (CAP/PTCR/OL) module.  
         [0010]    [0010]FIG. 2 is a bottom plan view of the run capacitor/positive temperature coefficient resistor/overload (CAP/PTCR/OL) module cover.  
         [0011]    [0011]FIG. 3 is a side view of a run capacitor/positive temperature coefficient resistor/overload (CAP/PTCR/OL) module cover.  
         [0012]    [0012]FIG. 4 is a plan view of a (CAP/PTCR/OL) module cover base with capacitor compartment cover removed.  
         [0013]    [0013]FIG. 5 is an exploded view of (CAP/PTCR/OL) module cover base with capacitor compartment cover removed.  
     
    
     DETAILED DESCRIPTION  
       [0014]    [0014]FIG. 1 is a cut away side view of a run capacitor/positive temperature coefficient resistor/overload (CAP/PTCR/OL) module  10  including a base  12  coupled to a cover  14 . In the exemplary embodiment, base  12  is a base PTCR/OL, model 3ARR55 PTCR/OL base available from GE Industrial Systems, Morrison, Ill. Base  12  includes a base surface  16  and a plurality of sidewalls  18 ,  20 ,  22  and  24  extending from base surface  16 . Sidewall  24  is cut away in FIG. 1. More specifically, sidewalls  18 ,  20 ,  22  and  24  define a partial compartment  26  with base surface  16 . Mounted within base compartment  26  is a PTCR  28  and an overload  30 . PTCR  28  is a disk type PTCR. In one embodiment, PTCR  28  is a PTCR disk available from Vishay Cera-Mite, Grafton, Wis. Terminal receiving connectors  32  and  34  are also positioned within base compartment  26 .  
         [0015]    Cover  14  couples to base  12  to form an enclosure with base  12 . Cover  14  is secured to base  12  using a rivet and/or heat staking treatment, for example, such that external contaminants which might damage PTCR disk  28  or overload  30  are prevented from entering into module  10 . In addition, cover  14  facilitates containing any failure that may occur within module  10 .  
         [0016]    Cover  14  includes a top surface  41  and a plurality of power lead openings  42  and  44 . Openings  42  and  44  are sized to receive leads from a power source (not shown). The specific configuration of openings  42  and  44  is variable depending on a user&#39;s preference. For example, in one embodiment, a dual receptacle plug is used. In the exemplary embodiment, power lead openings  42  and  44  are circumscribed by walls  43  and  45 , respectively. Walls  43  and  45  extend from cover top surface  41  and facilitate preventing an inadvertent reversed polarity connection of a power connector (not shown). In the exemplary, sidewalls  43  and  45  include a tab  46 . Tab  46  engages a pawl (not shown) on a power connector (not shown) to facilitate securely coupling the power connector to the power lead openings  42  and  44 .  
         [0017]    Cover  14  also includes a plurality of run capacitor terminal lead apertures  47  and  48  (shown in FIG. 2) circumscribed by a plurality of sidewalls  49 ,  50 ,  52  and  54  which are integrally formed with cover  14 . Sidewall  54  is cut away in FIG. 1. Sidewalls  49 ,  50 ,  52  and  54  extend from cover top surface  41  and form a partial compartment  56 . When cover  14  is fully assembled to base  12 , a run capacitor  58  and potting material (not shown) are contained within compartment  56 . A height of sidewalls  49 ,  50 ,  52  and  54  is variably sized depending on a size of capacitor used in the particular application. The potting compound covers run capacitor  58  and fills the entire compartment  56  and to facilitate protecting run capacitor  58  from moisture which may accumulate as a result of splashing or condensation. In one embodiment, the potting compound is UR-330, parts A and B, commercially available from Thermoset, Lord Chemical, Indianapolis, Ind.  
         [0018]    Run capacitor  58 , is a film capacitor with terminals  60  and  62  (shown in FIG. 2) electrically and mechanically attached to run capacitor  58 . Run capacitor terminal lead apertures  47  and  48  (shown in FIG. 2) extend through cover top surface  41 , and when cover  14  is coupled to base  12 , apertures  47  and  48  align with terminal receiving connectors  32  and  34  located in base  12 . Additionally, when cover  14  is coupled to base  12 , run capacitor terminals  60  and  62  are aligned with apertures  47  and  48  and connectors  32  and  34  such that connectors  32  and  34  receive terminals  60  and  62  in sliding engagement. In one embodiment, cover top surface  41  is shaped to extend arcuately into compartment  56  and facilitates reducing an amount of potting compound required to fill compartment  56 . A shape of top surface  41  is selected to substantially reduce an overall volume of compartment  56  while still permitting run capacitor  58  to be received therein.  
         [0019]    Cover  14  also includes a fastener opening  70  which, when cover  14  is coupled to base member  12 , aligns with an opening  72  formed in base  12 . In one embodiment, a rivet may be inserted through aligned openings  70  and  72  and crimped to maintain cover  14  secured to base  12 . In another embodiment, a plastic post replaces the eyelet to secure cover  14  to base  12  with heat stake of the plastic post. In still another embodiment, the cover  14  is secured to base  12  with an adhesive compound disposed along the upper edge of sidewalls  18 ,  20 ,  22  and  24 .  
         [0020]    [0020]FIG. 2 is a bottom plan view of the run capacitor/positive temperature coefficient resistor/overload (CAP/PTCR/OL) module cover  14  and illustrates an internal structure of cover  14 . More particularly, cover  14  includes a bottom surface  78 , opposing top surface  41 , an overload cavity  80  for receiving a portion of overload  30  and a PTCR cavity  82  for receiving a portion of PTCR disk  28 . An electrical barrier  85  provides spacing between power leads (not shown) which may be inserted through openings  42  and  44 . A plurality of platforms  88 ,  91 , and  94  are configured to be in substantial surface-to-surface contact with platforms (not shown) of base  12  and provide additional support for assembled module  10 . Electrical barriers  97  and  100  circumscribe apertures  47  and  48  and facilitate electrically isolating run capacitor terminals  60  and  62  from each other and overload  30 . Opening  70  extends through cover  14  to provide access to a similarly aligned fastener connection in base  12 . In another embodiment, opening  70 , is replaced by an alignment post.  
         [0021]    Cover  14  and base  12  may be formed from many different types of materials. In one embodiment, cover  14  and base member  12  are formed from electrically insulative plastic materials such as thermoplastic or thermoset materials utilizing an injection molding process. Terminals  60  and  62  may be formed, for example, from stainless steel, copper, brass or other well known conductive materials. Many different variations and modifications of module  10  are contemplated. For example, overload  30  could include one of many various other switches or cut-out controls. Also, rather than PTCR disk  28 , various other motor starter switches could be utilized.  
         [0022]    [0022]FIGS. 3, 4, and  5  show an alternative embodiment of the run capacitor/positive temperature coefficient resistor/overload (CAP/PTCR/OL) module cover. FIG. 3 is a side view of a run capacitor/positive temperature coefficient resistor/overload (CAP/PTCR/OL) module cover  214 . Cover  214  includes a base  215  coupled to a capacitor compartment cover  216 . FIG. 4 is a plan view of cover base  215  with capacitor compartment cover  216  removed. FIG. 5 is an exploded view of cover base  215  with capacitor compartment cover  216  removed. Identical components in FIGS. 3, 4 and  5  are numbered using the same reference numerals in each figure.  
         [0023]    When fully assembled, cover  214  is configured to couple to base  12  (shown in FIG. 1) in a similar manner as cover  14  (shown in FIG. 1).  
         [0024]    Capacitor compartment cover  216  is a hollow body that includes a plurality of sidewalls  218  (not shown),  220  (not shown)  222  and  224 . The sidewalls extend to an upper semi-cylindrical top  226  integrally formed with the sidewalls.  
         [0025]    Cover  214  includes a top surface  241  and a plurality of power lead openings  242  and  244 . Openings  242  and  244  are sized to receive leads from a power source (not shown). The specific configuration of openings  242  and  244  is variable depending on a user&#39;s preference. For example, in one embodiment, a dual receptacle plug is used. In the exemplary embodiment, power lead openings  242  and  244  are circumscribed by walls  243  and  245 , respectively. Walls  243  and  245  extend from cover top surface  241  and facilitate preventing an inadvertent reversed polarity connection of a power connector (not shown). In the exemplary embodiment, sidewalls  243  and  245  include a tab  246 . Tab  246  engages a pawl (not shown) on a power connector (not shown) to facilitate securely coupling the power connector to the power lead openings  242  and  244 .  
         [0026]    Cover  214  also includes a plurality of run capacitor terminal lead apertures  247  and  248  circumscribed by a plurality of sidewalls  249 ,  250 ,  252  and  254  which are integrally formed with cover  214 . Sidewalls  249 ,  250 ,  252  and  254  extend from cover top surface  241  and form a capacitor platform  256 . When cover  214  is fully assembled to capacitor compartment cover  216 , a run capacitor  258  and potting material (not shown) are contained within capacitor compartment cover  216 . A height of capacitor compartment cover sidewalls  218 , 220 ,  222  and  224  is variably sized depending on a size of capacitor used in the particular application. The potting compound covers run capacitor  258  and fills the entire capacitor compartment cover  216  to facilitate protecting run capacitor  258  from moisture which may accumulate as a result of splashing or condensation. In one embodiment, the potting compound is UR-330, parts A and B, commercially available from Thermoset, Lord Chemical, Indianapolis, Ind.  
         [0027]    Run capacitor  258 , is a film capacitor with terminals  260  and  262  electrically and mechanically attached to run capacitor  258 . Run capacitor terminal lead apertures  247  and  248  extend through cover top surface  241 , and when cover  214  is coupled to base  12  (shown in FIG. 1), apertures  247  and  248  align with terminal receiving connectors  32  (shown in FIG. 1) and  34  (shown in FIG. 1) located in base  12 . Additionally, when cover  214  is coupled to base  12 , run capacitor terminals  260  and  262  are aligned with apertures  247  and  248  and connectors  32  and  34  such that connectors  32  and  34  receive terminals  260  and  262  in sliding engagement.  
         [0028]    Cover  214  also includes a fastener opening  270  which, when cover  214  is coupled to base member  12 , aligns with an opening  72  (shown in FIG. 1) formed in base  12 . In one embodiment, a rivet  271  may be inserted through aligned openings  270  and  72  and crimped to maintain cover  214  secured to base  12 . In another embodiment, a plastic post replaces rivet  271  to secure cover  214  to base  12  with heat stake of the plastic post. In still another embodiment, the cover  214  is secured to base  12  with an adhesive compound disposed along the upper edge of sidewalls  18 ,  20 ,  22  and  24  (shown in FIG. 1).  
         [0029]    During assembly, capacitor  258 , and capacitor terminals  260  and  262  are coupled to capacitor platform  256  with terminal  260  extending through aperture  247  and terminal  262  extending through aperture  248 . Rivet  271  extends through aperture  270 . Capacitor compartment cover  216  is coupled to base  215  such that sidewalls  218 ,  220 ,  222  and  224  circumscribe capacitor platform  256 . Assembled cover  214  is inverted wherein capacitor compartment cover  216  forms a cup and potting material (not shown) is poured into cover  216  to a level sufficient to encapsulate capacitor platform  256 .  
         [0030]    The combination run capacitor, PTCR and overload module embodiments described herein provide the advantage that the motor run capacitor, PTCR and overload are disposed within one housing. The combination eliminates the need for a capacitor mounting post on the cover, which is the most impact sensitive structure on the cover. Further, the module can be easily and quickly coupled to an electric motor. Such a configuration reduces the expense associated with mounting such a run capacitor, PTCR and overload combination to an electric motor.  
         [0031]    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.