Abstract:
A drive sprocket for driving a modular belt having a plurality of belt modules with intercalated link ends connected by transverse pivot members to form hinges. The belt modules may have transverse ribs. The drive sprocket is driven by a shaft. The drive sprocket has a central opening for receiving the shaft. The body has a plurality of teeth disposed in pairs along a periphery of the body. The body has a first opening formed between adjacent pairs of teeth and extending toward the center of the sprocket to provide access to the hinge area, when the belt engages with the sprocket, for application of cleaning fluid.

Description:
FIELD OF THE INVENTION 
       [0001]    The present application is a continuation of U.S. patent application Ser. No. 11/672,568, filed on Feb. 8, 2007, now pending, the disclosure of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to modular conveying apparatus. 
       BACKGROUND OF THE INVENTION 
       [0003]    Sprockets for driving modular belts are usually made from stainless steel or plastic that is machined or molded. In food processing applications, sprocket drives are a particularly critical area for cleaning. It is important to be able to periodically remove the residual matters totally from the sprockets and on the rear side of the belt, in order to avoid bacteria growth and spoilage of the food processed on the belt. For this purpose sprockets have been designed with large openings to allow cleaning fluid to pass from the side and reach the critical areas to be cleaned. Such sprockets are disclosed in U.S. Patent No. Re. 38,607. Typically, the sprocket rim and teeth are covering the hinges and hinder the fluid from reaching the hinge area for proper cleaning. Therefore the sprocket disclosed in the patent further provides pairs of teeth in a double row such that the teeth of a pair are offset. This arrangement allows better cleaning access to the rear belt side and easier release of residual matters collected on the rear belt side. But this design is only partially solving the problem since the critical hinge areas are still covered by the sprocket rim to a certain extent, when engaged on the sprocket. Therefore good access to these hinges is of primary importance. 
         [0004]    U.S. Patent Publication No. 2004/0222072 proposes to solve this problem by using a sprocket with an oblique shape as illustrated in  FIGS. 3A ,  3 B of the publication. With this design, the teeth will laterally change their position on the rear side of the belt and regularly expose another place on the belt for better cleaning access. Although this is improving cleanability, the proposed solution is still having the shortcoming of periodically covering the hinge completely in a certain position. Another typical feature of the disclosed sprocket is the tracking on the belt by additional teeth engaging in the hinge gaps ( FIG. 3B , reference no.  74 ). During sprocket engagement these teeth enter into the hinge gap between two links and thus push residual matter into this gap, making it again difficult to clean. Also, the drive pockets (reference  72  as shown in  FIG. 3A  of the publication) of the sprocket are engaging closely over the drive faces which are identical with the center cross bar on the rear side of the belt. The drive surfaces totally covered by the enclosing drive pocket are another place where residuals are physically squeezed in between thus making cleaning more difficult. 
         [0005]    Another patent proposing a similar solution is U.S. Pat. No. 6,740,172. The patent does not disclose the drive engagement but discloses sectional sprockets used to laterally shift the engagement area periodically. 
         [0000]    Accordingly, there is a need for an improved sprocket for easy cleaning that avoids the above described shortcomings. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention meets the above described need by providing a drive sprocket for driving a modular belt having a plurality of belt modules with intercalated link ends connected by transverse pivot members to form hinges. The belt modules may have transverse ribs. The drive sprocket is driven by a shaft. The drive sprocket has a central opening for receiving the shaft. The body has a plurality of teeth disposed in pairs along a periphery of the body. The body has a first opening formed between adjacent pairs of teeth and extending toward the center of the sprocket to provide access to the hinge area, when the belt engages with the sprocket, for application of cleaning fluid. 
         [0007]    The sprocket may also be provided with a curved recessed portion adjacent to the first opening. A plurality of second openings may be disposed in the body of the sprocket between the central opening and the first opening. 
         [0008]    The pairs of teeth may be arranged in offset fashion with respect to a central axis or the teeth may extend for the entire with of the sprocket. 
         [0009]    A cleaning system may be arranged proximate to the sprockets such that cleaning fluids are sprayed through the curved recessed portion into the opening disposed adjacent to the hinge of the belt when the belt engages with the sprocket. The cleaning system may include a manifold in combination with spray heads pointed toward the sprocket. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The invention is illustrated in the drawings in which like reference characters designate the same or similar parts throughout the figures of which: 
           [0011]      FIG. 1  is a side elevational view of a sprocket according to a first embodiment of the present invention; 
           [0012]      FIG. 2  is an end elevational view of the sprocket shown in  FIG. 1 ; 
           [0013]      FIG. 3  is a side elevational view of the sprocket shown in  FIG. 1  with a modular belt engaged thereon; 
           [0014]      FIG. 4  is a perspective view thereof; 
           [0015]      FIG. 5  is another perspective view thereof; 
           [0016]      FIG. 6  is an alternate embodiment of the sprocket of the present invention; 
           [0017]      FIG. 7  is a side elevational view of another alternate embodiment of the present invention; 
           [0018]      FIG. 8  is an end elevational view of the sprocket shown in  FIG. 7 ; 
           [0019]      FIG. 9  is a perspective view of the sprocket shown in  FIG. 7  with a belt engaged thereon; 
           [0020]      FIG. 10  is a side elevational view of another alternate embodiment of the present invention; 
           [0021]      FIG. 11  is an end elevational view of the sprocket of  FIG. 10 ; 
           [0022]      FIG. 12  is a side elevational view of the sprocket of  FIG. 11  with a modular belt engaged thereon; 
           [0023]      FIG. 13  is perspective view thereof; 
           [0024]      FIG. 14  is a schematic view of sprockets of the present invention in combination with a spraying system; and, 
           [0025]      FIG. 15  is a side elevational view of another alternate embodiment of the present invention; 
           [0026]      FIG. 16  is an end elevational view of the sprocket shown in  FIG. 15 ; and, 
           [0027]      FIG. 17  is a perspective view of the sprocket of  FIG. 15  with a belt engaged thereon. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    Referring initially to  FIG. 1 , a drive sprocket  20  has a plurality of sprocket teeth  23 ,  26  disposed in pairs  27  around the periphery of the sprocket  20 . The sprocket  20  also has a central opening  29  that is formed in the shape of a square. The square shaped opening  29  is sized to receive a square shaft  30  ( FIG. 14 ) for rotating the sprocket  20  to drive a modular belt  32  ( FIG. 3 ). The central opening  29  may be formed in other shapes to accommodate different shaft geometries as will be evident to those of ordinary skill in the art based on this disclosure. A large first opening  35  which may be oval-shaped as shown is formed in the body of the sprocket  20 . The first opening  35  is located between adjacent pairs  27  of teeth and is arranged such that it aligns with the hinge area of the module belt  32  when the belt  32  is engaged with the sprocket  20  as best shown in FIG.  3 . As shown the teeth  23  are formed by a pair of side walls  38 ,  41  (opposite to wall  38 ); a pair of end walls  44 ,  47 ; and a top wall  50 . The teeth  26  are formed by a pair of side walls  53 ,  56  (opposite to wall  53 ); a pair of end walls  59 ,  62 ; and a top wall  65 . The top walls  50  and  65  are angled relative to their respective side walls such that the top walls  50  and  65  are disposed in spaced apart relation and somewhat aligned with respect to their planar top surfaces. The sprocket  20  also has recessed curved portions  68  extending from the end of the first openings  35  toward the center of the sprocket  20 . The curved recessed portions  68  extend toward the teeth  23 ,  26  and terminate at a shelf-like portion  71  between the respective teeth. 
         [0029]    Turning to  FIG. 2 , the teeth  23 ,  26  are disposed in two rows along the periphery of the drive sprocket  20 . The teeth  23 ,  26  are offset along the circumference of the sprocket and are disposed on opposite sides of a central axis  28  such that during driving of the modular belt  32  one of the teeth engages with one of the link ends  33  of the belt  32  and another tooth engages with the transverse rib  34  on the belt  32 . The shelf portion  71  extends between adjacent teeth  23 ,  26  and is bordered on opposite sides by the curved recessed portions  68 . 
         [0030]    Turning to  FIG. 3 , the sprocket  20  is shown engaged with the modular belt  32 . The teeth  23 ,  26  engage with the link ends  33  and transverse rib  34  of the respective belt modules  36 . The teeth  23 ,  26  fit on opposite sides of the transverse rib  34  and provide tracking for the belt  32 . Also, the first openings  35  provide large openings and improved access to the hinge areas for cleaning when the belt  32  passes over the drive sprocket  20 . The curved recessed portions  68  also provide room near the hinge and guide the cleaning fluid into the critical hinge area. 
         [0031]    Turning to  FIGS. 4 and 5 , the end wall  47  of the tooth  23  may be disposed at an angle such that the face of the tooth  23  reduces the contact surface to the belt  32  and “squeezes” away residuals that may become trapped between the belt  32  and the sprocket  20 . 
         [0032]    In  FIG. 6 , an alternate embodiment of the sprocket  20  is shown. Sprocket  60  has the same design for the teeth  23 ,  26  and the first openings  35  and curved, recessed portions  68  but also includes openings  63  which are relatively large and are positioned around the periphery of the central shaft opening. The openings  63  may be desired to improve the accessibility for water jets applied from the sides of the sprocket  60 . This alternate design does not necessarily improve the cleaning of the hinge areas. 
         [0033]    Turning to  FIGS. 7-9 , an alternate embodiment of the sprocket body that is particularly suitable for molding is shown. Sprocket  80  has a central opening  81  and has larger curved, recessed portions  83  that follow the offset (with respect to the circumference as best shown in  FIG. 8 ) arrangement of the sprocket teeth pairs  86 ,  89 . The teeth are disposed in pairs  91  with each tooth on opposite sides of a central axis  94 . The curved recessed portion  83  extends from the end wall  92  of one tooth  86  to the end wall  95  of the next tooth  86  on the same side of the sprocket  80 . A first opening  98  formed between adjacent teeth  86 ,  89  provides an opening around the hinge area. The pairs  91  of sprocket teeth  86 ,  89  provide for engagement of the transverse rib  34  and link end  33  of belt  32  as shown in FIG.  9 . The recessed portion  83  is disposed at an angle β with respect to the radial axis  93 . The angle β may be altered as necessary to improve the flow of cleaning fluid. 
         [0034]    Turning to  FIGS. 10-13 , an alternate embodiment of the sprocket is shown. Sprocket  110  has a central opening  114 . Sprocket  110  increases the open space between the sprocket  110  and the hinge of the belt  32 . The sprocket  110  may be used where tracking is not needed such as where the belt  32  is guided by guiding profiles on the edge of the belt  32 . As best shown in  FIG. 11 , the sprocket  110  has a single row of teeth pairs  113 ,  116  without any offset. Due to the wider teeth  113 ,  116  and the closed V-shape of the space  118  between the teeth  113 ,  116 , the sprocket  110  contact area is larger and may negatively effect the cleaning properties of the sprocket  110 . The sprocket  110  also includes a curved, recessed portion  121 . The recessed portion  121  extends to a first opening  124  that aligns with the hinge area of belt  32  as shown in  FIG. 12 . 
         [0035]      FIG. 14  illustrates an arrangement of a spraying system include a manifold  150  with spray heads  153  arranged adjacent to sprockets  20  such that cleaning fluid  156  can be sprayed through the curved recessed portions  68  into the first openings  35  below the hinge areas of the modular belts  32  as they pass over the drive sprocket  20 . 
         [0036]    Turning to  FIG. 15 , another embodiment of the sprocket is shown. A drive sprocket  200  has a plurality of sprocket teeth  203 ,  206  disposed in pairs  207  around the periphery of the sprocket  200 . The sprocket  200  also has a central opening  209  that is formed in the shape of a square. The square shaped opening  209  is sized to receive a square shaft  30  ( FIG. 14 ) for rotating the sprocket  200  to drive a modular belt  32  as shown in  FIG. 17 . A plurality of first openings  215  are disposed around the periphery of the sprocket  200  between the pairs  207 . The first openings  215  extend inward toward the center of the sprocket  200  and terminate along a curved inner wall  218 . A plurality of second openings  221  are disposed between the first openings  215  and the central opening  209 . The second openings  221  may be desired to improve the accessibility of water jets applied from the sides of the sprocket  200 . Sprocket  200  does not include recessed portions or grooves below the first opening  215 . The sprocket  200  is intended to have smooth surfaces with large openings to provide access to the hinge area of the belt and to allow easier cleaning of the sprocket itself. 
         [0037]    In  FIG. 16 , the teeth  203 ,  206  are disposed in two rows along the periphery of the drive sprocket  200 . The teeth  203 ,  206  are offset along the circumference of the sprocket  200  and are disposed on opposite sides of a central axis  230 . During driving of the modular belt  32  one of the teeth engages with one of the link ends  33  of the belt  32  and another tooth engages with the transverse rib  34  on the belt  32 . The transverse rib  34  on the belt  32  fits in the space  238  between the teeth  203 ,  206 . 
         [0038]    Turning to  FIG. 17 , the sprocket  200  is shown engaged with the modular belt  32 . The teeth  203 ,  206  engage with the link ends  33  and transverse rib  34  of the respective modules  36 . The teeth  203 ,  206  fit on opposite sides of the transverse rib  34  and provide tracking for the belt  32 . Also, the first openings  215  provide large openings and improved access to the hinge areas for cleaning when the belt  32  passes over the drive sprocket  200 . As indicated by arrow  250  the first openings  215  align with the hinge areas of the belt  32  as the belt  32  passes over the sprocket  200 . 
         [0039]    While the invention has been described in connection with certain embodiments, it is not intended to limit the scope of the invention to the particular forms set forth, but, on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.