Abstract:
A conveyor  20  comprising a continuous conveyor belt  35 , driven at a constant speed, and configured for compression and expansion along the direction of travel of the continuous conveyor belt  35 . The continuous conveyor belt  35  passes over a drive pulley  32  and a secondary pulley  34  that freely rotates. At least one impulse linkage  37  engages the continuous conveyor belt  35 , the impulse linkage  37  extends beyond the continuous conveyor belt  35  such that it may be contacted by an impulse striker  49  that is configured to intermittently contact said impulse linkage  37 . By so contacting the impulse linkage  37 , a displacement of a portion of the continuous conveyor belt  35  relative to the rest of the continuous conveyor belt  35  is caused due to the subsequent expansion or compression of the continuous conveyor belt  35 , resulting in a localized acceleration.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to a conveyor system, and more particularly to a surface conveyor system with a variable delivery rate along the length of the conveyor. 
     BACKGROUND OF THE INVENION 
     Conveyor systems are well known in the prior art, including those where objects are conveyed at varying rates at different portions of the conveyor. This is often desired in that various processes may occur at different points along the conveyor that require more or less time to complete than would be provided by a conveyor operating at a constant rate. For example, it is common to have machines along a common conveyor that conduct their operations at varying rates. As well, in order to maximize efficiency, uniformity of product spacing along these conveyors is often desired. 
     In order to keep product at various points on the conveyor for required periods of time, prior art systems often have conveyors that operate intermittently (i.e., the conveyor would be indexed from one position to the next, remaining stationary for a period of time at discrete intervals). One problem that arises with an indexing system is that conveyor efficiency is adversely effected because product spacing tends to be non-uniform. For example, product congregates in the vicinity of slower processes, thereby causing a lack of product at other points along the conveyor. As well, these systems tend to be noisy and the components are generally subject to considerable wear. 
     Therefore, there is a need for improved systems and methods which address these and other shortcomings of the prior art. 
     SUMMARY OF THE INVENTION 
     The present invention is generally directed to a conveyor with a continuous conveyor belt, driven at a constant speed and being configured for compression and expansion along the direction of travel of the continuous conveyor belt. The continuous conveyor belt passes over a first and a second pulley, the first pulley being a drive pulley and the second pulley being a secondary pulley that freely rotates. At least one impulse linkage is disposed on the continuous conveyor belt, the impulse linkage has a portion that extends beyond the continuous conveyor belt in a plane perpendicular to the direction of travel of the continuous conveyor belt. Also, an impulse striker is configured to intermittently contact the impulse linkage, thereby causing a displacement of a portion of the continuous conveyor belt relative to the rest of the continuous conveyor belt due to the subsequent expansion or compression of the continuous conveyor belt. 
     The present conveyor also provides a method for conveying with varying rates of delivery along the conveyor length. The method includes the steps of driving a portion of a continuous conveyor belt at a constant rate, placing a product on the continuous conveyor belt, and accelerating a portion of the continuous conveyor belt in a direction parallel to the direction of travel of the continuous conveyor belt. 
     Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention. In the drawings: 
     FIG. 1 is a side view of a preferred embodiment of the present invention; 
     FIG. 2 is a side view of the conveyor of FIG. 1, showing detail of the conveyor; 
     FIGS. 3A and 3B are side views of the conveyor of FIG. 2, including the impulse conveyor and a cutaway portion of the primary conveyor in order to show how the striker of the impulse conveyor engages the impulse linkage of the primary conveyor to cause a localized acceleration in a preferred embodiment; and 
     FIGS. 4A and 4B are top schematic representations of the continuous conveyor belt sections of FIGS. 3A and 3B. 
     Reference will now be made in detail to the description of the invention as illustrated in the drawings. While the invention will be described in connection with these drawings, there is no intent to limit it to the embodiment or embodiments disclosed therein. On the contrary, the intent is to cover all alternatives, modifications and equivalents included within the spirit and scope of the invention as defined by the appended claims. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the drawings, FIG. 1 illustrates the general arrangement of a conventional bread bagger  10  that deposits bagged loaves  13  of bread onto the upper flight  22  of a surface conveyor  20 . An input conveyor  14  delivers freshly baked loaves  12  of bread to the bagger  10  that has lower and upper scoops  16  and  18 , respectively, for receiving the loaves  12 . A supply of bread bags (not shown) is maintained on the side of conveyor  20 , opposite scoops  16  and  18 . The loaves  12  are deposited by the input conveyor  14  on the lower scoop  16  of the bagger  10  and the upper scoop  18  and lower scoop  16  straddle the loaf  12  and enter the open end of an inflated bag at the side of the conveyor  20 . The scoops  16 ,  18  move apart to hold the mouth of the bag open. The scoops  16 ,  18  are then retracted to their starting position on the side of the conveyor  20  opposite the bread bags, during which time they pull the open end of the inflated bag about the loaf  12 . The scoops  16 ,  18  are withdrawn from the bag and the bagged loaf  13  is deposited on a conveyor  20 . The conveyor  20 , shown as a preferred embodiment of the present invention, then clears the bagged loaf  13  in order to allow further bagging. 
     As shown in FIG. 2, the conveyor  20  includes a primary conveyor  30  having a drive pulley  32  and associated secondary pulley  34 . A continuous conveyor belt  35  is wrapped around the drive pulley  32  and secondary pulley  34  of the primary conveyor  30  and includes upper and lower flights  22  and  24 , respectively, and the intermittently spaced impulse linkages  37 . The impulse conveyor  40  has an impulse drive pulley  42 , a secondary impulse pulley  44 , a guide pulley  46 , and a continuous striker chain  48 . The guide pulley  46  is positioned so that the upper flight of the continuous striker chain  48  between the secondary impulse pulley  44  and the guide pulley  46  runs substantially parallel to the upper flight  22  of the continuous conveyor belt  35  of the primary conveyor  30 . This provides the impulse striker  49 , located on the continuous striker chain  48 , the opportunity to engage the impulse linkage  37  at any point along length of the continuous conveyor belt  35  as defined from the lowermost point of the secondary pulley  34  up to the point directly above the centerline of the impulse guide pulley  46 . Note, however, that in another embodiment of the present invention, the guide pulley  46  can be omitted so long as the impulse drive pulley  42  is positioned such that the impulse striker  49  can still engage the impulse linkage  37 . 
     In the preferred embodiment represented in FIG. 2, the continuous conveyor belt  35  includes a plurality of interlocking compressible conveyor segments  36  so that the continuous conveyor belt  35  may be compressed to effect a localized acceleration. At set intervals along the continuous conveyor belt  35  are placed impulse linkages  37 . In the preferred embodiment shown, the impulse linkages  37  have an upper portion  38  and a lower portion  39  that are attached to an interlocking compressible conveyor segment  36  of the continuous conveyor belt  35  so that the upper portion  38  extends outwardly from the continues conveyor belt  35 . The lower portion  39  of the impulse linkage  37  extends inwardly from the continuous conveyor belt  35 . This construction allows the upper portion  38  of the impulse linkage  37  to engage the product and help impart an acceleration thereon by preventing slippage of the product along the continuous conveyor belt  35  surface when the lower portion  39  of the impulse linkage  37  is contacted by the impulse striker  49 . However, the upper portion  38  may be excluded, as an acceleration may still be imparted on the product by way of the product&#39;s direct contact with the interlocking compressible conveyor segments  36  of the primary conveyor  30 . 
     Operation 
     The conveyor  20  of the present invention includes a primary conveyor  30  with variable delivery rate along the continuous conveyor belt  35  and may be used to move product placed on the surface of the continuous conveyor belt  35  during operations while maintaining uniform product spacing. The operation of the conveyor  20  will now be described. 
     A drive, such as an electric motor (not shown), rotates drive pulley  32  (FIG. 2) of the primary conveyor  30 , at a continuous rate. Teeth on the drive pulley  32  engage the continuous conveyor belt  35  so that the continuous rate of the drive pulley  32  is imparted on the continuous conveyor belt  35 . As shown in FIG. 3A, the continuous conveyor belt  35  passes about the secondary pulley  34  of the primary conveyor  30  and returns to the drive pulley  32  so that a continuous loop is formed by the continuous conveyor belt  35  about pulleys  32  and  34 . A drive, such as an electric motor (not shown), rotates impulse drive pulley  42 , which imparts motion to the continuous striker chain  48 . As previously noted, the continuous striker chain  48  passes about the secondary impulse pulley  44  and guide pulley  46 , forming a continuous loop. The secondary pulley  34  of the primary conveyor  30  and the secondary impulse pulley  44  rotate about a common shaft  45  that extends transverse to the direction of motion of the continuous conveyor belt  35 . However, both the secondary pulley  34  and the secondary impulse pulley  44  are free to rotate independently of the other, i.e. at different rates. 
     As previously noted (FIG.  1 ), loaves  12  of bread are transferred to the bagger  10  by an input conveyor  14  and deposited on the lower scoop  16 . The loaves  12  are then bagged as is known in the prior art and are lowered onto the conveyor  20  of the present invention. The continuous conveyor belt  35  is driven by drive pulley  32  at a constant rate. In order to keep the bagged loaves  13  uniformly spaced and prevent the bagging operation from causing a slow down in the overall operation of the conveyor  20 , it is desirable to transfer the bagged loaves  13  from the bagging area so as to provide space for the oncoming loaves  13 . This is accomplished by producing a localized acceleration of a portion of the continuous conveyor belt  35  in the vicinity of the bread bagger  10 . 
     FIGS. 3A and 3B show how the present invention creates a localized acceleration of the continuous conveyor belt  35 . In order to create the localized acceleration on the continuous conveyor belt  35 , the impulse conveyor  40  is operated at a faster rate than that of the primary conveyor  30 . The rate chosen for the impulse conveyor  40  is dependent upon a number of factors, such as desired product spacing, the period of time it takes to perform a given process, spacing of the impulse linkages  37 , and the rate at which the continuous conveyor belt  35  is driven. The secondary impulse pulley  44  is configured such that the impulse striker  49  contacts the lower portion  39  of the impulse linkage  37  as the impulse striker  49  rotates about the secondary impulse pulley  44 . In so doing, the impulse striker  49  exerts force on the lower portion  39  of the impulse linkage  37 . As shown, the impulse striker  49  makes contact with the impulse linkage  37  at a point (Point A) directly above the centerline of both the secondary pulley  34  and secondary impulse pulley  44 , which is the beginning of the upper flight  22  of the continuous conveyor belt  35  of the primary conveyor  30 . Note that at the moment the impulse striker  49  contacts the impulse linkage  37 , the smallest possible overlap regions  41  exist between adjacent interlocking compressible conveyor segments  36 . This is because the continuous conveyor belt  35  is being pulled by the drive pulley  32  (FIG. 2) of the primary conveyor  30 , thereby causing maximum extension of the interlocking compressible conveyor segments  36 . Also note Point A was chosen for convenience of description and that the initial point of contact between the impulse striker  49  and the impulse linkage  37  may vary. 
     In that the impulse conveyor  40  is operating at a faster rate than that of the primary conveyor  30 , the impulse striker  49  maintains contact with the impulse linkage  37  until the impulse striker  49  reaches Point B, as shown in FIG.  3 B. Point B lies on the centerline of the guide pulley  46 . The result of the engagement of the impulse striker  49  with the impulse linkage  37  between Points A and B is a localized acceleration of the continuous conveyor belt  35 . As the impulse striker  49  travels from Point A to Point B, the impulse striker  49  urges the impulse linkage  37  and the interlocking compressible conveyor segment  36  to which the impulse linkage  37  is attached at the faster rate of the impulse conveyor  40 . By so urging the impulse linkage  37 , the impulse conveyor  40  causes relative motion between the interlocking compressible conveyor segments  36  forward of the impulse linkage  37  relative to the direction of motion. The resultant relative motion of the interlocking compressible conveyor segments  36  results in greater overlap regions  41  between the interlocking compressible conveyor segments  36  closest to the front of the impulse linkage  37 . Note that the overlap regions  41  between adjacent interlocking compressible conveyor segments  36  become smaller as one moves farther away from the impulse linkage  37 . Overlap between adjacent interlocking compressible conveyor segments  36  results in an overall compression of the continuous conveyor belt  35 , and hence, a localized acceleration. In turn, a product in contact with this portion of the continuous conveyor belt  35  will undergo an acceleration as well. The upper portion  38  of the impulse linkage  37  is not a required element of the present invention, however, in the preferred embodiment, the upper portion  38  helps align the slices of the loaves  12  (FIG.  1 ), serves to prevent product slippage and helps ensure that the localized acceleration is imparted on the product. By exerting either a greater or lesser force on the impulse linkage  37  via the impulse striker  49 , due to the speed difference therebetween, a greater or lesser compression of interlocking compressible conveyor segments  36  will take place. Hence, a greater or lesser localized acceleration is imparted on the continuous conveyor belt  35 . 
     Note that although the primary conveyor  30  is driven at a continuous rate during steady state operation, it is possible to vary the rate at which the primary conveyor  30  is driven without affecting the performance of the conveyor  20  (FIG.  2 ). A new continuous rate for steady state operation can be achieved so long as the ratio of the speeds at which the drive pulley  32  (FIG. 2) and the impulse drive pulley  42  are driven remains constant. 
     FIG. 4A is a top view schematic of FIG. 3A, when the impulse striker  49  has made initial contact with the impulse linkage  37  at Point A. Note that all of the overlap regions  41  are of equal size, and their smallest possible values. This is because, as previously discussed, no force has been exerted on the impulse linkage  37  by the impulse striker  49  as of yet. Rather, the continuous conveyor belt  35  is being pulled in the direction indicated by the drive pulley  32  (FIG. 2) of the primary conveyor  30 . Therefore, the continuous conveyor belt  35  is under tension and adjacent interlocking compressible conveyor segments  36  are extended to their maximum extent. FIG. 4B is a top view schematic of FIG. 3B, showing the effect of the force exerted by the impulse striker  49  on the impulse linkage  37  between Points A and B. The overlap regions  41  forward of the impulse linkage  37  are greatest closest to the impulse linkage  37 , and gradually get smaller as one moves away from the impulse linkage  37  and the force imparted by the impulse striker  49  on the impulse linkage  37  is dissipated. Again note that the overlap regions  41  aft of the impulse linkage  37  are uniform and the smallest possible size due to that segment of the continuous conveyor belt  35  being under tension. Note that the distance between Points A and B is selected by determining the position at which the guide pulley  46  (FIGS. 3A and 3B) is located. 
     It should be emphasized that the above-described embodiments of the present invention, particularly, any preferred embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiment(s) of the invention without departing substantially from the spirit and principles of the invention. For example, alternate embodiments of the present invention could include a device such as a pneumatic striker rather than the impulse conveyor  40  to impart a localized acceleration on the primary conveyor  30 . All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.