Abstract:
A roller conveyor using a motorized drive roller has the drive roller located other than in the terminal roller position of conveyor zones. Damage to the motorized drive roller from overheating or impact loads is minimized.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation in part of Schmutzler Ser. No. 60/698,825 filed Jul. 13, 2005. 

   BACKGROUND OF THE INVENTION 
   A roller conveyor may be powered by a motor housed in a cylindrical roller. In such a conveyor the rollers are typically arranged in sections or zones of 8 or more rollers, with one or two motorized drive rollers. One or both of the terminal rollers of the zone is a drive roller. The rollers between the terminal rollers may be driven from the motorized drive roller as by O-ring-like belts. One or more conveyor belts may extend around the terminal rollers and across the intermediate carrying rollers for better traction, or to carry small products. The conveyor belts restrict air flow to the motorized terminal rollers which can lead to overheating and damage to the motor. The terminal roller, particularly at the transition between an inclined zone and a horizontal or level zone, is subject to impacts from conveyed articles which may damage the motor. 
   BRIEF SUMMARY OF THE INVENTION 
   The motorized drive roller of a roller conveyor zone is located other than at the terminal position of the zone and is preferably in the plane of the zone rollers, adjacent the terminal roller and serves as a carrying roller. The motorized drive roller has a drive connection to at least the adjacent terminal roller. A conveyor belt extends around the terminal roller. The motorized drive roller is not subject to impact loads which are absorbed by the terminal roller; and the surface of the motorized drive roller is substantially completely exposed to air, enhancing cooling. 

   
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is a perspective view of a roller conveyor zone with a motorized drive roller in accordance with the invention; 
       FIG. 2  is a plan view thereof as indicated by line  2 - 2  of  FIG. 1 ; 
       FIG. 3  is an end view thereof looking from the left end of  FIG. 1 ; 
       FIG. 4  is a side view thereof as indicated by line  4 - 4  of  FIG. 3 ; 
       FIG. 5  is a side view of a modified motorized roller drive; 
       FIG. 6  is a fragmentary side view of a roller conveyor showing the transition from a horizontal zone to an ascending incline zone. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A conveyor  10  has spaced apart side plates  12 ,  14  between which are mounted plurality of rollers that form a level conveying surface. Terminal rollers  16 ,  18  define a run-on-demand conveyor zone, the operation of which may be controlled to accumulate and move product. In the embodiment shown in  FIG. 1-4 , motorized drive rollers  20 ,  22  serve also as product carrying rollers and are located adjacent terminal rollers  16 ,  18 . The motorized drive rollers may be secured from Itoh Denki, USA or other suppliers. Several carrying rollers,  24 , are located between motorized drive rollers  20 ,  22 , depending on the length of the zone. The rollers have axles at each end received in openings in the side plates and isolated by plastic bushings (not shown) as described in Houghton U.S. Pat. No. 5,645,155, to reduce noise and wear. 
   A drive connection, as an O-ring-like drive belt, connects each motorized drive roller,  20 ,  22  with the adjacent terminal roller,  16 ,  18 . Motor controls  28 ,  30  are mounted on side plate  14  and connected through electrical cables  32 ,  34  with the motors (not shown) inside motorized rollers  20 ,  22 . Drive connections (not shown) may also be provided to carrying rollers  24  with O-ring-like drive belts. 
   Conveyor belts  38 ,  40  and  42  extend around the terminal rollers  16 ,  18  and across the motorized rollers  20 ,  22  and carrying rollers  24 . The conveyor belts provide additional traction for conveyed product which is particularly important on an inclined conveyor. The belts also prevent small articles falling between rollers. As noted above, were the motorized roller in the terminal roller position a conveyor belt extends around 180° of the roller surface. This blocks airflow to the roller and leads to overheating which can damage the roller. Where the motorized roller located other than in the terminal position the likelihood of overheating is reduced. 
   A modified embodiment of the invention is illustrated in  FIG. 5  where the motorized rollers  20   a ,  22   a  are off-set below terminal rollers  16   a ,  18   a.    
   The transition from a horizontal conveyor zone,  46 , to an up-incline zone  48  is illustrated in  FIG. 6 . An article  50 , passing through the transition as indicated by arrow  52  strikes the terminal roller  54  of the up-incline zone  48 . If the terminal roller  54  were a motorized drive roller, the motor might be damaged by the impact and require replacement. Here, however, the motorized drive roller  56  is not the terminal roller and is isolated by the terminal roller  54  so as not to be subject to the impact load from article  50 . Similarly, a source of damage to the motorized drive roller is eliminated.