Abstract:
A tensioning device ( 10 ) is provided. The tensioning device ( 10 ) includes a housing ( 15 ) and a first pulley ( 16 ) removably coupled to the housing for selective positioning of the first pulley ( 16 ) relative to a second pulley ( 16 ) to adjust tension associated with a drive element ( 18 ) extending between the first and second pulleys ( 16 ).

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 11/454,606, filed Jun. 16, 2006, which claims the benefit of Provisional Application No. 60/691,005, filed Jun. 16, 2005, the disclosures of which are hereby expressly incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    A conventional drive system often includes a flexible drive element, or drive belt that interconnects at least two drive elements, such as drive sheaves. The drive system requires maintenance to ensure satisfactory performance and durability of the belt. Correct operating tension is a factor in the satisfactory performance and life of any drive belt. In fact, drive belts wear at an increased rate if they are allowed to run with insufficient tension. As drive belts wear they seat themselves deeper in the sheave grooves. This seating, along with belt stretch, lessens the initial tension. The result is vibration, slippage, and loss in horsepower capacity unless some form of take-up is used to restore and maintain the original tension. On the other hand, too much tension in the belt can lead to excessive belt and bearing wear. 
         [0003]    One way to adjust the belt tension is through the use of a tensioning device. A tensioning device may be used to bias one or both of the drive belt runs inwardly toward the other run at a point intermediate the drive sheaves. The tensioning device may instead bias one or both of the drive belt runs outwardly away from the other run at a point intermediate the drive sheaves. Using a tensioning device to constantly provide a suitable amount of tension to the drive belt increases the life of the drive system. 
       SUMMARY 
       [0004]    A tensioning device is provided. The tensioning device includes a housing and a first pulley removably coupled to the housing for selective positioning of the first pulley relative to a second pulley to adjust tension associated with a drive element extending between the first and second pulleys. 
         [0005]    This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0006]    The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
           [0007]      FIG. 1  is an isometric view of a tensioning device coupled to a drive system; and 
           [0008]      FIG. 2  is a partially exploded isometric view of the tensioning device of  FIG. 1  coupled to a drive system. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]      FIGS. 1 and 2  illustrate a preferred embodiment of a tensioning device  10  constructed in accordance with the present disclosure. Referring to  FIG. 1 , the tensioning device  10  is used in connection with a conventional drive system  11 . Although the tensioning device  10  may be used with any conventional drive system, the illustrated drive system  11  includes a driving element  20  and a driven element  22  interconnected by a flexible drive element  18 . The flexible drive element  18  may be any standard belt, such as a V-belt, a flat drive belt, a grooved belt, etc. 
         [0010]    The flexible drive element  18  is preferably a V-belt having two ribs formed on the interior of the belt. The drive element  18  is formed as a complete loop and passes around the first driving element  20  and the second driving element  22  to provide continuous driving force. The drive element  18  includes an upper run  19  extending between the upper sides of the elements  20  and  22 , and a lower run  21  extending between the lower sides of the elements  20  and  22 . 
         [0011]    The driving element  20  and driven element  22  may be any suitable element such as a pulley, sheave, etc. Preferably, the driving and driven elements  20  and  22  are sheaves having two grooves formed along the exterior perimeter thereof for receiving the ribs of the drive element  18 . The drive element or drive sheave  20  drives the drive element  18 , and the drive element  18  drives the driven element or driven sheave  22 . 
         [0012]    Referring to  FIG. 2 , the tensioning device  10  includes a housing  15  having a first end plate  12  and a second end plate  14  and a gap defined therebetween. The first and second end plates  12  and  14  preferably have a substantially similar rectangular shape; however, other shapes are also within the scope of this disclosure. A plurality of apertures  24  are formed in each corner of the first and second end plates  12  and  14 , wherein a first group of apertures  24 A are formed in a first corner, a second group of apertures  24 B are formed in a second corner, a third group of apertures  24 C are formed in a third corner, and a fourth group of apertures  24 D are formed in a fourth corner. Preferably, the apertures  24  formed in each respective corner of the first end plate  12  substantially mirror the apertures  24  formed in each respective corner of the second end plate  14 . 
         [0013]    A plurality of pulleys  16  are rotatably mounted between the first and second end plates  12  and  14  of the housing  15 . Preferably, four standard V-belt pulleys  16 A,  16 B,  16 C, and  16 D are mounted within the housing  15 , wherein each pulley includes two pulley grooves  30  formed around its exterior circular perimeter. Each V-belt pulley  16 A,  16 B,  16 C, and  16 D includes a central through-bore  26  that houses a bushing or bearing assembly (not shown). V-belt pulley  16 A is rotatably fastened between the first and second end plates  12  and  14  by passing a suitable fastener, such as a screw, shaft, bolt, etc., through one of the apertures  24 A in the first end plate  12 , through the central bore  26  of pulley  16 A, and through one of the apertures  24 A in the second end plate  14 . The other V-belt pulleys  16 B,  16 C, and  16 D are rotatably fastened between the first and second end plates  12  and  14  in a similar fashion. The bushing or bearing assembly permits rotation of each V-belt pulley  16 A,  16 B,  16 C, and  16 D about its center axis defined by the central through-bore  26 . 
         [0014]    The cross-section of the pulley grooves  30  substantially conform in shape and size to the cross-section of the ribs of the drive element  18  so that the V-belt pulleys  16 A,  16 B,  16 C, and  16 D are engageable with the drive element  18 . The tensioning device  10  can be located between the upper and lower runs  19  and  21  on the drive element  18  intermediate the sheaves  20  and  22 . As an example, the tensioning device can be positioned such that pulleys  16 B and  16 C engage the ribs on the upper run  19  and pulleys  16 A and  16 D engage the ribs on the lower run  21 . The tensioning device  10  pushes the upper and lower runs  19  and  21  of the drive element  18  away from each other. In this manner, the slack is removed from the drive element  18 , thereby decreasing belt wear and substantially reducing the possibility that the belt  18  will come off one of the sheaves  20  or  22 . 
         [0015]    The tensioning device  10  is free floating in that it is held in position solely by the tension in the upper and lower runs  19  and  21  of the drive element  18 . In this manner, the tensioning device  10  dampens shock and vibration rather than adding to the vibration generated from the sheaves  20  and  22 . Moreover, the free floating design of the tensioning device  10  allows for easy installation, adjustment, and removal. 
         [0016]    The tensioning device  10  may be adjusted while remaining positioned on the drive element  18  to increase or decrease the tension of the drive element  18 . To adjust the tension, the V-belt pulleys  16 A- 16 D may be repositioned within the housing  15  to either increase or decrease the spacing between the pulleys  16 A- 16 D disposed within the tensioning device  10 . As shown in  FIGS. 1 and 2 , each corner of the first and second end plates  12  and  14  include a vertical row of apertures  24 . The pulley position may be adjusted by passing the fastener  28  through an aperture  24  either closer to or further away from the corner of the end plates  12  and  14 . When the pulleys  16 A- 16 D are repositioned closer to the corner of the end plates  12  and  14 , the spacing between the pulleys is increased. The tensioning device  10  therefore pushes the upper and lower runs  19  and  21  further away from each other, and the tension in the drive element  18  is increased. When the pulleys  16 A- 16 D are repositioned further away from the corner of the end plates  12  and  14 , the spacing between the pulleys is decreased. As such, the tensioning device  10  does not exert as much force against the upper and lower runs  19  and  21 , and the tension in the drive element  18  is decreased. 
         [0017]    The pulley positions may also be horizontally repositioned within the housing  15  to either increase or decrease the width between the pulleys. The width between the pulleys may need adjustment to ensure that the tensioning device  10  is properly positioned between the sheaves  20  and  22 . As shown in  FIGS. 1 and 2 , each corner of the first and second end plates  12  and  14  includes a horizontal row of apertures  24 . The pulley position may be adjusted by passing the fastener  28  through an aperture  24  either closer to or further away from the corner of the end plates  12  and  14 . 
         [0018]    By only adjusting one pulley  16  at a time, the tensioning device  10  does not need to be removed from the drive element  18 . The pulleys  16 A- 16 D can be adjusted as needed on the tensioning device  10  so as to constantly apply a suitable tensioning force to the drive element  18 . 
         [0019]    It should be appreciated that the tensioning device  10  can also be positioned such that pulleys  16 B and  16 C engage the outer surface of the upper run  19  and pulleys  16 A and  16 D engage the outer surface of the lower run  21 . For instance, if the drive system  11  included a flexible drive element  18  that had the same inner and outer surface shape, such as a flat drive belt, the drive element  18  could be received within flat-grooved pulleys  20 ,  22 ,  16 A,  16 B,  16 C, and  16 D on either side of the belt. The tensioning device  10  would again be free floating in that it would be held in position solely by the tension in the upper and lower runs  19  and  21  of the drive element  18 . Moreover, the tensioning device  10  would push the upper and lower runs  19  and  21  inwardly towards each other to remove the slack in the drive element  18 . This arrangement maintains a greater surface area of the drive belt in contact with the outer surface of the sheaves  20  and  22  at any given time. 
         [0020]    The tensioning device  10  may be similarly adjusted while remaining positioned on the outer surface of the drive element  18  to increase or decrease the tension of the drive element  18 . To adjust the tension, the V-belt pulleys  16 A- 16 D may be vertically repositioned within the housing  15  to either increase or decrease the distance between pulleys  16 A and  16 B and between pulleys  16 C and  16 D. The pulley position may be adjusted by passing the fastener  28  through an aperture  24  either closer to or further away from the corner of the end plates  12  and  14 . When the pulleys  16 A- 16 D are repositioned further away from the corner of the end plates  12  and  14 , the distance between pulleys  16 A and  16 B and between pulleys  16 C and  16 D is decreased and, therefore, the tension in the drive element  18  is increased. When the pulleys  16 A- 16 D are repositioned closer to the corner of the end plates  12  and  14 , the distance between pulleys  16 A and  16 B and between pulleys  16 C and  16 D is increased and, therefore, the tension in the drive element  18  is decreased. The pulley positions may be horizontally repositioned within the housing  15  to either increase or decrease the width between the pulleys, as described above. 
         [0021]    While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.