Abstract:
An intermediate roller for driving a carrying roller of an accumulating roller conveyor and including a sprocket wheel for engaging a chain of the accumulating roller conveyor, a mating gear for engaging a gear connected with the carrying roller, the mating gear being arranged coaxially with the sprocket wheel and being fitted together with the sprocket wheel, with the sprocket wheel and the mating gear having cooperating form-locking elements defining a chamber for receiving a damping element for providing a limited circumferential backlash between the sprocket wheel and the mating gear.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an intermediate roller for driving carrying rollers of an accumulating roller conveyor. An accumulating roller conveyor is a conveyor that includes sectionally driven carrying rollers on which articles are transported. During their transportation, the articles act on a sensing element projecting in the conveyor path. The sensing element controls engagement or disengagement of the elements of a conveyor drive for changing the conveyor output in accordance with local conditions. 
     There exist accumulating roller conveyors which include an intermediate roller comprising a sprocket wheel, which engages a circulating chain. The driven wheel, which is drivingly connectable with the carrying roller, can be formed as a gear. This results in a twofold form-locking motion transmission. On one hand, such motion transmission advantageously insures a reliable and efficient transportation of articles but, on the other hand, it may cause a detrimental forcible slippage between the engaged drive elements if the conveying of articles is blocked. 
     The latter may result in the damage of conveyor parts and/or the articles, especially with a high power input. Further, during connection of the sprocket wheel with the driven wheel, difficulties exist in bringing the teeth of the two parts into engagement with each other, and a noticeable impact of teeth on each other can be observed. 
     German Patent No. 2,650,205 which discloses an accumulating roller conveyor, discloses a concept which insures a substantial insensitivity to disturbances during the starting period and, at the same time, provides for a high constant transmission of drive forces. 
     In German Patent No. 2,650,225, a combination of safety clutches and special toothing provides for a reliable overload protection during engagement and disengagement of form-locking parts with which drive force tansmission is effected. 
     German Patent No. 2,650,205 discloses an accumulating roller conveyor in which an intermediate roller, formed as a sprocket wheel, drives the article-carrying rollers and is displaced between its drive and free-running positions by a linkage which cooperates with a sensing element projecting in the conveyor path. 
     According to the German patent, the outer surface and the hub of the carrying roller, which is driven by the intermediate roller, form, in a per se known manner, a slide bearing, and the drive connection between the intermediate roller and the carrying roller is provided by flattened toothing. 
     In this accumulating roller conveyor, good results are achieved with regard to force transmission. However, with regard to the start, i.e., the time at which the carrying roller is set in rotation, start impacts can still be present. 
     Accordingly, an object of the invention is to provide an intermediate roller which would insure that the forces, generated at the beginning of driving of the conveyor, are dampened. 
     SUMMARY OF THE INVENTION 
     This and other objects of the invention are achieved by providing an intermediate roller comprising a sprocket wheel for engaging a chain of the accumulating roller conveyor, and a mating gear for engaging a gear connected with the carrying roller and arranged coaxially with and fitted together with the sprocket wheel, with the sprocket wheel and the mating gear having cooperating form-locking elements defining at least one chamber for receiving a damping element for providing at least a limited circumferential backlash between the sprocket wheel and the mating gear. 
     The intermediate roller, according to the present invention, insures a reliable conveying and pressureless accumulation of conveyed articles. 
     The sprocket wheel and the mating gear form together a slide bearing which provides for limited relative rotation therebetween. The limitation of their mutual relative rotation is insured by appropriate form-locking elements, which engage each other after the limited relative rotation between the two parts, the sprocket wheel and the mating gear. The delayed engagement of the form-locking elements, upon fitting of the two parts into each other, is insured by the appropriate geometry of the cooperating form-locking elements. To this end, the corresponding form-locking elements of the sprocket wheel and the mating gear are so dimensioned, that their thickness is less than the desired length of the relative rotation path. 
     The cooperating form-locking elements of the sprocket wheel and the mating gear form chambers the volume of which is reduced or increased during the relative rotation of the sprocket wheel and the mating gear. 
     According to the invention, damping elements are placed in these chambers. These elements are formed of a compressible material. During run-on of the rollers, the damping element is compressed due to the relative rotation of the sprocket wheel and the mating gear, and absorbs the &#34;starting impact&#34;. The forces generated during the start are transmitted to the damping element and slightly compress it until form-locking is obtained. 
     According to one embodiment of the invention, the sprocket wheel is provided, on a side thereof adjacent to the mating gear, with a coaxial cylindrical bearing shoulder, which has a diameter smaller than the dedendum diameter of the sprocket wheel. The sprocket wheel hub is formed as a sleeve having an outer diameter smaller than the diameter of the bearing shoulder. 
     The form-locking elements are arranged on the bearing shoulder concentrically to the axis of the sprocket wheel. Preferably, the form-locking elements extend transverse to the bearing shoulder and are formed as webs, with the upper surface of the form-locking elements being somewhat set back with respect to the upper surface of the hub. 
     The sprocket wheel, the bearing shoulder, the hub, and the form-locking element are preferably formed as a one-piece part made of a plastic material. However, the hub may also be formed as a separate sleeve subsequently assembled with the sprocket wheel proper. 
     The mating gear is formed as a hollow body and has, at one side thereof, an opening communicating with the hollow space, through which the bearing shoulder and form-locking elements of the sprocket wheel are inserted. That provides for coaxial arrangement of the sprocket wheel and the mating gear. The side of the mating gear adjacent to the sprocket wheel is closed with an end wall through which a bore for receiving a bearing extends, in which bore the hub of the sprocket wheel is received. 
     Inside of the hollow space of the mating gear concentrically to the axis of the mating gear, there are provided radially extending, with respect to the bearing bore, form-locking elements. Preferably, the form-locking elements are formed as webs extending transverse to the end wall. 
     As in the sprocket wheel, the upper surface of the webs is set back with regard to the upper surface of the mating gear opening. The inner surfaces of the form-locking elements of the mating gear are aligned with the bearing bore so that both have substantially the same inner diameter. The mating gear and its form-locking elements are preferably formed as a one-piece part made of a plastic material. 
     The inner surfaces of the form-locking elements of the mating gear serve as bearing shell parts for the hub of the sprocket wheel. The inner diameter of the hollow space of the mating gear serves as a bearing shell which receives the bearing shoulder of the sprocket wheel and its form-locking elements. Thus, the two parts, the sprocket wheel and the mating gear, cooperate with each other to drive the carrying roller, while a limited relative rotation therebetween is provided by appropriate dimensioning of their form-locking elements, which form-lockingly engage each other after the limited relative rotation of two parts took place. This became possible by inserting damping elements between the form-locking elements of the two parts. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects and features of the present invention will become more apparent, and the invention itself will be best understood, from the following detailed description of the preferred embodiment when read with reference to the accompanying drawings, wherein: 
     FIG. 1 is an interior view of a frame for housing an intermediate roller, according to the present invention; 
     FIG. 2 is a cross-sectional view along line A--A in FIG. 1; 
     FIG. 3 is a side view of an intermediate roller, according to the present invention; 
     FIG. 4 is a view of the intermediate roller shown in FIG. 3 taken in the direction of arrow B; 
     FIG. 5 is a view of the intermediate roller shown in FIG. 3 taken in the direction of arrow C; 
     FIG. 6 is a front elevational view of a sprocket wheel; 
     FIG. 7 is a cross-sectional view of the sprocket wheel shown in FIG. 6 taken along line D--D; 
     FIG. 8 is a front elevational view of a mating gear; 
     FIG. 9 is a cross-sectional view of the mating gear shown in FIG. 8 taken along line E--E in FIG. 8; 
     FIG. 10 is a perspective view of the sprocket wheel; 
     FIG. 11 is a perspective view of the mating gear; 
     FIG. 12 is a cross-sectional view of the intermediate roller shown in FIG. 4 taken along line F--F and showing the connection of the sprocket wheel and the mating gear, which together form the intermediate roller according to the present invention; 
     FIG. 13 is a cross-sectional view of the intermediate roller shown in FIG. 12 taken along line G--G; and 
     FIG. 13a is a view showing a portion of an intermediate roller similar to the roller shown in FIG. 13. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2 show an intermediate roller 1, according to the present invention, which is mounted in an accumulating roller conveyer. As shown in FIG. 1, a frame 29 for housing the intermediate roller 1 is provided on the inner side of the accumulating roller conveyer. 
     The accumulating roller conveyor is formed of two parallel frames 29 between which a carrying roller 33 is rotatably supported. The carrying roller is supported on an axle 34 on which a gear 35 is also mounted. For simplicity, the gear 35 is designated with its addendum &#34;dkz&#34; and dedendum &#34;dfz&#34; circles, which are shown with dash-dot lines. 
     The axle 34 is fixed in the frame 29, and the carrying roller 33 and the gear 35 are rotatably mounted on the axle 34. A transporting means, a chain 32, is continuously movable in the space between the carrying roller 33 and the gear 35 and a lower flange 36 of the frame 29. A sprocket wheel 2, which forms a part of the intermediate roller 1, engages the chain 32. For simplicity, the sprocket wheel 2 in FIG. 1 is also designated with its addendum &#34;dkk&#34; and dedendum &#34;dfk&#34; circles shown with dash-dot lines. 
     The intermediate roller 1 also includes a mating gear 3 which engages the gear 35. The mating gear 3, like the sprocket wheel 2 and the gear 35, is designated with its addendum &#34;dkg&#34; and dedendum &#34;dfg&#34; circles likewise shown with dash-dot lines. 
     The sprocket wheel 2 and the mating gear 3 together form the intermediate roller 1. The intermediate roller 1, together with combined axles 8 and 19 of the sprocket wheel 2 and the mating gear 3, is rotatably supported inside a housing 31. The housing 31, together with the intermediate roller 1, formed of sprocket wheel 2 and the mating gear 3, is pivotable about a pivot axis 30. An adjusting member 37, which is actuated by a sensing element (not shown) arranged in the conveyor path of the accumulating conveyor and which is secured to the housing 31, provides for engagement and disengagement of the mating gear 3 of the intermediate roller 1 and the gear 35 of the carrying roller 33. 
     Due to such cooperation of the driving and driven elements, the sprocket wheel 2 remains in constant engagement with the chain 32. FIGS. 3-5 shown the intermediate roller 1 taken out of the frame 29. As it has already been discussed above, the intermediate roller is formed of the sprocket wheel 2 and the mating gear 3. The sprocket wheel 2 and the mating gear 3 are formed as separate parts which fit into each other with their respective axes being coaxial with each other. 
     A hub 12 of the sprocket wheel 2 projects outwardly from an end surface 38 of the sprocket wheel 2 and forms an elongate bearing support. The hub 12 extends from an opposite end surface 9 of the sprocket wheel 2, which is adjacent to the mating gear 3, to serve as a bearing for the mating gear 3. The mating gear 3 is provided on its end wall 20, which is remote from the sprocket wheel 2, with a bearing shoulder 39. As a result, a portion of the hub 12 projecting from the end surface 38 of the sprocket wheel 2 defines an end collar 40, and another end collar is formed by the bearing shoulder 39 on the end wall 20 of the mating gear 3. 
     FIG. 4 shows that the addendum &#34;dkk&#34; of the sprocket wheel represents the largest dimension of the intermediate roller 1, and that the mating gear 3 or its addendum diameter &#34;dkg&#34; is located inside the dedendum diameter &#34;dfk&#34; of the sprocket wheel 2. In FIG. 4, the end surfaces of the hub 12 of the sprocket wheel 2 and the bearing shoulder 39 of the mating gear 3 are shown as surrounding the bearing bore 21. 
     The sprocket wheel 2, which forms a part of the intermediate roller 1 according to the present invention, is shown in detail in FIGS. 6 and 7. The sprocket wheel 2 has, on an end surface 9 thereof, adjacent to the mating gear 3, a bearing shoulder 10 coaxial with the axis of the sprocket wheel 2. The diameter &#34;d&#34; of the bearing shoulder 10 is noticeably smaller than the diameter &#34;dfk&#34; of the dedendum 11 of the sprocket wheel 2. The hub 12 of the sprocket wheel 2 extends transversely to the bearing shoulder 10. 
     The hub 12 is formed as a bearing sleeve and is provided with a bore 21. The diameter &#34;dn&#34; of the hub is smaller than the diameter &#34;d&#34; of the bearing shoulder 10. The outer circumference 26 and the outer surface 27 define a plurality of separate form-locking elements 4 radially extending on the bearing shoulder 10 around the hub 12 and which form, in cooperation with respective elements of the mating gear 3, corresponding slide bearing elements. 
     In the embodiment shown in FIGS. 6 and 7, the form-locking elements 4 are formed as webs arranged transversely to the bearing shoulder 10. A step 15 is formed between an outer surface 13 of the form-locking elements 4 and an outer surface 14 of the hub 12. The form-locking elements 4 define respective chambers 6 therebetween, which will be discussed in more detail below. 
     FIGS. 8 and 9 show an embodiment of the mating gear 3 which forms part of the intermediate 1, according to the present invention. The mating gear 3, as clearly shown in the drawings, is a hollow body. The mating gear 3 has, at a side 16 thereof adjacent ot the sprocket wheel 2, a hollow space 17 communicating with an opening 18. About the axis of the mating gear 3 in the end wall 20 of the mating gear 3, there are provided, transverse to the end wall 20, webs defining form-locking elements 5 of the mating gear 3. 
     The form-locking elements 5 also form separate chambers 6. A step 41 is formed between the outer surface 22 of the mating gear 3 and the outer surface 23 of the form-locking elements 5. The inner surfaces 24 of the form-locking elements 5 are aligned with an inner diameter &#34;di&#34; of the mating gear bore 42. The inner circumference 28 of the mating gear 3 is aligned with an outer circumference 27 of the form-locking elements 4 of the sprocket wheel 2 and to an outer circumference 26 of the bearing shoulder 10. The inner surfaces 24 of the form-locking elements 5 correspond to a circumference 25 of the hub 12 of the sprocket wheel 2. Thereby, a sliding bearing is formed. 
     FIGS. 10 and 11 show, respectively, perspective views of the sprocket wheel 2 and the mating gear 3, and FIG. 12 shows a cross-sectional view of the sprocket wheel 2 and the mating gear 3 in their assembled condition in which they form the intermediate roller 1, according to the present invention. In FIGS. 10-12, elements identical with respective elements shown in FIGS. 1-9 are designated with the same reference numerals. In FIG. 12, reference numeral 7 designates a damping element. 
     FIG. 13, which represents a cross-sectional view of the intermediate roller 1 shown in FIG. 12, shows a relative position and a circumferential backlash of the sprocket wheel 2 and the mating gear 3. 
     In the assembled condition, the sprocket wheel 2 and the mating gear 3 define spaces 43 in which the damping elements 7 are located. In the position shown in FIG. 13, the damping element 7 is not compressed as no power transmission takes place. When the mating gear 3 engages the gear 35 of the carrying roller 33, the form-locking elements 4 and 5 are rotated toward each other until a form-locking connection is obtained. 
     In the absence of the damping element 7, the form-locking elements 4 and 5 would have impacted on each other. The damping element 7 dampens the power transmission force applied to the form-locking elements 4 and 5, and no deceleration takes place so that the driving movement is transmitted without any delay. 
     As shown in FIG. 13a, the form-locking elements 4 and 5 can have a conical shape which insures a uniform application of compression forces to the damping element. 
     The intermediate roller, according to the present invention, which drives the carrying roller of an accumulating roller conveyor, insures reliable conveying and pressureless accumulation of conveyed articles by including a damping element between form-locking elements of the sprocket wheel and the mating gear, which together form the intermediate roller which damping element eliminates starting impact forces, thereby preventing any drive deceleration. 
     While the present invention was shown and described with reference to the preferred embodiment, various modifications will be apparent to those skilled in the art and, therefore, it is not intended that the invention be limited to the disclosed embodiment and/or details thereof, and departures can be made therefrom within the spirit and scope of appended claims.