Abstract:
Brush holder assemblies are detailed. The assemblies permit on-line brush replacement and are interchangeable with devices currently provided by original equipment manufacturers. As well, they allow use of brushes longer than those employed in existing on-line replacement assemblies.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to brush holders and associated equipment and more particularly, but not exclusively, to brush holder assemblies compatible with existing riggings and which allow safer and easier on-line changes of brushes. The assemblies additionally may permit use of longer brushes than current commercially-available assemblies, increasing the time between brush changes. 
       BACKGROUND OF THE INVENTION 
       [0002]    U.S. Pat. No. 4,800,313 to Warner, et al., whose contents are incorporated herein in their entirety by this reference, details examples of brush holders for use with carbon brushes. These holders utilize ribbon springs so as to provide essentially constant biasing force to the brushes. They are, in at least this aspect, conventional, as the use of constant biasing force is known generally to reduce maintenance, prevent performance problems, and increase the useful lives of the brushes. 
         [0003]    Commutators or slip rings and associated carbon brushes and holders are used in numerous industrial contexts. Some such uses are for power generation. Collector brush riggings provided by original equipment manufacturers (OEMs) typically accept certain brush-holder designs, many of which are not designed to allow easy brush replacement while equipment is operating. Consequently, when a brush is worn such that its useful life has expired, the corresponding power-generation equipment must cease operation before the brush may be replaced safely. In practice, however, some equipment operators replace brushes without ceasing operation of the equipment, conduct carrying a high risk of injury. 
         [0004]    Efforts have been made to supply improved brush holders which permit on-line replacement of brushes. Currently-available holders of this type are expensive and cumbersome, however, or may require extensive or expensive modifications to the associated equipment (such as the brush holder support system). In many cases, the replacement brush holders accept brushes significantly shorter than the original-equipment brushes and are not interchangeable with existing OEM devices. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention resolves issues associated with these types of brush holders. Assemblies of the invention both permit safer and easier on-line brush replacement and are interchangeable with existing original-equipment devices. As well, they allow use of brushes with length equal to or, in most cases, longer than currently-available replacement brush holder assemblies, with preferred assemblies of the invention accepting brushes approximately four inches long. The brush holders also may be configured to accept original OEM brushes or brushes with improved terminations. 
         [0006]    The invention additionally may provide extra support to brushes, diminishing adverse effects of vibration on their wear. It is substantially less cumbersome than prior efforts and significantly less costly to produce. Handles forming part of the assemblies also are removable for reuse, so that only one handle is necessary regardless of the number of assemblies employed. 
         [0007]    It thus is an optional, non-exclusive object of the present invention to provide innovative brush holder assemblies. 
         [0008]    It is also an optional, non-exclusive object of the present invention to provide brush holder assemblies permitting safer and easier on-line replacement of brushes. 
         [0009]    It is an additional optional, non-exclusive object of the present invention to provide brush holder assemblies that are interchangeable with ones provided by OEMs. 
         [0010]    It is another optional, non-exclusive object of the present invention to provide brush holder assemblies adapted to accept brushes equal in length to or longer than corresponding conventional assemblies and which can be configured to be interchangeable with original-equipment brushes. 
         [0011]    It is a further optional, non-exclusive object of the present invention to provide brush holder assemblies capable of supplying enhanced vibrational support for brushes, reducing adverse effects of vibrations on their usefulness. 
         [0012]    Other objects, features, and advantages of the present invention will be apparent with reference to the remaining text and the drawings of this application. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0013]      FIG. 1  is a perspective view of an exemplary brush holder assembly of the present invention with a handle attached. 
           [0014]      FIG. 2  is a perspective view of the assembly of  FIG. 1  with the handle removed. 
           [0015]      FIG. 3  is an exploded view of the assembly of  FIG. 1 . 
           [0016]      FIG. 4  is a partial cut-away view of the assembly of  FIG. 1 . 
           [0017]      FIGS. 5-6  are close-up views of portions of the assembly of  FIG. 1  illustrating attachment of the handle. 
           [0018]      FIG. 7  is a close-up view of portions of the assembly of  FIG. 1  illustrating interaction of features of a brush holder and a support. 
           [0019]      FIG. 8  is a perspective view of the assembly of  FIG. 1  with the support being used to facilitate insertion of a brush. 
           [0020]      FIG. 9  is a close-up, cut-away view of aspects of the brush holder and support. 
       
    
    
     DETAILED DESCRIPTION  
       [0021]    Detailed in  FIGS. 1-4  is brush holder assembly  10  of the present invention. Assembly  10  comprises brush holder  14  and support  18 . At times, it additionally may comprise handle  22  and one or more fasteners such as bolts  26 . In use, assembly  10  is configured to receive and retain brush B while biasing the brush B toward a surface of a rotating device such as a commutator or slip ring. 
         [0022]    Included as part of holder  14  are brush box  30 , spring  34 , and back plate or section  38 . Box  30  is designed to receive at least a portion of brush B and to support and restrain some movement of the brush B during operation. It preferably is integrally formed with section  38 , although it need not necessarily be so formed. Instead, for example, box  30  may be a separate component fastened or otherwise connected to section  38 . Holder  14  additionally may be configured to accommodate various forms and dimensions of boxes presently in use in OEM holders. 
         [0023]    Spring  34 , as shown in  FIGS. 1-4 , may be a ribbon spring or other biasing means attached to either or both of box  30  or section  38 . When brush B is retained within assembly  10 , spring  34  contacts (nominally) top surface  42  and biases (nominally) bottom surface  46  of brush B toward a rotating device. As brush B wears, spring  34  tends to roll up, always supplying substantially constant bias force to the brush B. 
         [0024]      FIGS. 1-4  illustrate section  38  as of generally rectangular, elongated shape. Although it may be shaped in any suitable way, section  38  preferably includes groove  50  into which support  18  may be fitted. Section  38  additionally may include (nominally) top surface  54  with bore  58  formed therein as well as electrical connector  62 . Although shown as a quick-connect type terminal, connector  62  may be a terminal screw or any other suitable mechanism for providing an electrical connection to lead L of brush B. 
         [0025]    Bore  58  preferably has the complex shape shown especially in  FIG. 2 . Bore  58  receives handle  22  during removal and replacement of brush B. Unlike certain other holders, however, handle  22  is not necessarily permanently received by bore  58 . Instead, handle  22  may be removable therefrom when brush holder  14  is installed onto support  18 . Since handle  22  is suitably insulated with adequate distance between its grip  70  (see  FIG. 4 ) and adjacent equipment, handle  22  may be removed while the equipment is energized or rotating. This allows handle  22  to be used to replace brushes in other assemblies on the rigging and permits its insulation to remain clean, as it may be stored away from the rigging environment when not in use. 
         [0026]    As best illustrated in  FIGS. 3-4 , handle  22  may comprise guard or base  66 , grip  70 , shaft  74 , and coil spring  78 . Both base  66  and grip  70  are electrically insulated on their outer surfaces, and grip  70  is fastened to shaft  74  so they rotate together. When handle  22  is in use, base  66  abuts top surface  54  of brush holder  14  and grip  70  is configured to be grasped, pushed, and turned by an operator. Shaft  74 , which may include pin  82 , is designed to fit into bore  58 , with the pin  82  engaging slot  86  (see  FIG. 5 ) of the bore  58 . Those skilled in the art will recognize that other methods of connecting handle  22  and brush holder  14  may be used instead, however, if appropriate or desired. 
         [0027]      FIGS. 5-6  detail initial insertion and locking of handle  22  into brush holder  14 . As shown in  FIG. 5 , shaft  74  of handle  22  may be inserted into bore  58  so that pin  82  is aligned with slot  86 . Slot  86  communicates with second slot  90  of brush holder  14 , which is oriented generally perpendicular thereto. Because slot  86  communicates with second slot  90 , as shaft  74  is inserted further into bore  58 , pin  82  may travel down slot  86  until it reaches second slot  90 . 
         [0028]    Once pin  82  reaches second slot  90 , an operator may start to turn handle  22  and then cease pushing down on the handle  22  while continuing to turn (rotate) it. This rotation moves pin  82  into second slot  90  (preferably toward the center position thereof). The operator may continue turning handle  22  until pin  82  snaps into this center position (into the center lobe of slot  90 ; see  FIG. 6 ). This action effectively locks handle  22  to brush holder  14 . 
         [0029]    Support  18  preferably comprises an elongated, generally rectangular structure with T-shaped cross-section, such as that shown especially in  FIG. 3 . T-slot shaped groove  50  of brush holder  14  may be fitted onto support  18  so that support  18  fits within T-slot groove  50 . Contact spring  102  biases a surface of brush B or brush holder  14  against support  18 , thereby both precisely positioning the brush holder  14  and providing consistent electrical contact between brush holder  14  and support  18 . Brush holder  14  also may be removed from support  18  when appropriate. 
         [0030]    Included within or as part of support  18  are bushing  94 , return spring  98 , contact spring  102 , and pin  106  (see  FIG. 4 ). Also included as part of support  18  may be pin  110  ( FIG. 7 ) together with one or more bores  114  (see  FIG. 3 ). Depending on the function of support  18 , a bore  114  may receive either a bolt  26  (or other fastener) or a brush-changing handle  118  ( FIG. 8 ). Pin  110  may move brush retainer  130  of brush holder  14  away from a surface of brush B immediately before holder  14  is fully seated onto support  18 . Release of retainer  130  (which preferably is a spring) allows brush B to move freely in brush box  30 , which is essential for proper brush operation. Before retainer  130  is moved off the surface of brush B, brush holder  14  securely holds brush B against unwanted movement during installation or removal. 
         [0031]    To install a new or replacement brush B, an operator may use changing handle  118  attached to support  18  (thereby converting these parts to a brush-changing fixture). This configuration need not be as shown in  FIG. 8 , however. Instead, it may comprise any lever or other object able to facilitate lifting of retainer  130  when the object is inserted into brush holder  14  to facilitate installation of a new brush. 
         [0032]    This brush-changing fixture may be slid into groove  50  of holder  14 . Typically, the brush-changing fixture will be placed on a flat surface and brush holder  14  slid down over the fixture along its length until they are seated together. This approach is not mandatory, however; instead, for example, the brush-changing fixture may simply be slid upward into T-slot groove  50  of holder  14  until they are seated together. 
         [0033]    After fully inserting support  18  into holder  14 , an operator may rotate handle  22  again so as to lock support  18  to holder  14 . Suitably rotating handle  22  causes shaft  74  to engage and rotate bushing  94  and pin  82  to be positioned as shown in  FIG. 9 , effectively locking support  18  and holder  14  together. As well, full insertion of support  18  into holder  14  causes pin  110  to lift brush retainer  130  (see  FIG. 7 ), permitting insertion of brush B into box  30  of holder  14 . 
         [0034]    Once support  18  and holder  14  are locked together, brush B may be inserted through end  134  of box  30 . Usually (although again not necessarily), bottom surface  46  of brush B is placed on a flat surface and box  30  slid over brush B. This action causes spring  34  to contact top surface  42  of brush B and to begin to unroll. When brush B is adequately inserted into box  30  (i.e. when bottom surface  46  is approximately flush with end  134  of box  30 ), handle  22  may be rotated so as to unlock support  18  from holder  14 . Changing handle  118  may then be grasped and support  18  removed from holder  14 , which disengages pin  110  from brush retainer  130 . Disengagement of pin  110  allows brush retainer  130  to move toward its normal (relaxed) position; however, an edge of retainer  130  contacts brush B before retainer  130  reaches its relaxed position, thereby causing retainer  130  to be biased against brush B to restrain unwanted brush movement. Lead L of brush B then may be connected to connector  62 . 
         [0035]    All of these above-described activities may occur away from any rotating or energized device. After installation of brush B into brush holder  14 , holder  14  may be re-installed on support  18  which is mounted on the equipment, reseating the T-slot groove  50  onto the T-section of the equipment support  18 . After this seating, handle  22  may be turned again to lock brush holder  14  to support  18  and then may be removed for use elsewhere or for storage. Bolts  26  may be used to fasten support  18  to the equipment rigging; however, this is done only during initial installation of the support  18  and need not occur during normal operation, normal brush changing, or maintenance of brushes. 
         [0036]    Because assembly  10  permits replacement of brush B away from a rotating or energized device, the device need not be de-energized while replacement occurs. (As noted earlier, this is because the brush holder is removed from the rotating or energized device using an insulated handle  22 , then specific operations to replace the brush B are completed away from device.) Further, because preferred versions of assembly  10  are sized similarly to existing brush holders, they may readily be interchanged with such existing holders. Accordingly, retrofit of existing power-generation or other systems may occur with little or no modification to the brush holder support systems. Assembly  10  also is cost-effective to produce (and thus lowers initial cost to the purchaser) and to operate and maintain and is configured to accept longer brushes B than are generally employed with current replacement offerings. Indeed, assembly  10  as configured can permit further growth in the length of section  38  along with a longer spring  34  to allow an even longer brush B with accompanying longer brush life and reduced maintenance of collector systems. Assembly  10  can also provide enhanced vibrational and other support for longer brushes B, since the brush box  30  is longer than in most conventional holders. 
         [0037]    The foregoing is provided for purposes of illustrating, explaining, and describing exemplary embodiments and certain benefits of the present invention. Modifications and adaptations to the illustrated and described embodiments will be apparent to those skilled in the relevant art and may be made without departing from the scope or spirit of the invention.