Abstract:
The conveyor system includes a conveyor bed mounted on a frame and an endless conveyor belt moving between upper and lower flight pads relative to the conveyor bed. A separate drive unit for the belts includes an enclosed housing having an opening therein through which the conveyor bed passes. The housing contains a belt drive mechanism including a plurality of belt pulleys engaged with the belt for receiving the conveyor belt from one of the upper and lower flight pads, applying motor power to the belt, and returning it to the other of the flight pads. The enclosure also includes a UV irradiation light source interposed in the path of travel of the belt through the housing for disinfecting the surfaces of the belt and the interior of the housing as the belt passes therethrough.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to conveyor systems, and more particularly to a conveyor system using a continuous conveyor belt particularly adapted for the food service industry for transporting food trays and the like, including an ultraviolet irradiation system for disinfecting the conveyor belts at a position remote from the portion of the conveyor used to convey food products. 
   2. Background of the Invention 
   In hospitals and other institutions which have a centralized food preparation location, meals are often prepared along a conveyor belt carrying food trays across a series of stations at which appropriate meal portions, dishes or beverages are placed on the conveyor. Such conveyors typically have a straight flight path with an endless belt supported on pulleys defining the path. The belt typically will run in an upper flight path on which the trays are carried, and a lower flight path below a conveyor bed. The lower flight path is either exposed to whatever is below that flight path, or is contained within a support plate to try to prevent contamination of food products or the like that may be moved below the conveyor. 
   Because of the continuous operation of these belts in a large room where various food products are handled, it is possible for the conveyor belts to become contaminated with food products, bacteria or the like. Typically, in the past, such conveyors were periodically taken out of operation and sanitized using soaps and decontaminating chemicals. This is a time consuming and expensive process. To overcome that, it has been proposed in the past to devote a section of the conveyor&#39;s surface path of travel to passage through a hooded housing containing a plurality of UVC lights to expose the belt to irradiation from the lights for disinfection. Such previously proposed UV disinfection systems take up a substantial amount of space on the useful conveyor surface, and may require food products on the conveyor belt to pass through the UV light housing itself. 
   In addition, access to the belt in these housings is difficult and the housing size will vary depending on belt speeds. Thus, for example, the faster the belt speed the longer the housing must be in order to properly decontaminate the belt. 
   Some of the problems associated with prior art conveyor belts for the food service industry have been overcome by the conveyor system disclosed in U.S. Pat. No. 5,052,548, the disclosure of which is incorporated herein by reference. 
   As disclosed in that patent, the conveyor system is used for transporting food trays, soiled trays and the like. The system includes a frame which defines a conveyor path of travel of relatively great length, and typically having one or more horizontal curves or turns therein. A pair of corresponding conveyor beds are mounted on the frame and define upper flight paths to move the food trays or soiled trays thereon. In food preparation, a plurality of work stations are positioned along one side edge of each of the conveyor beds. A different item, such as food or beverage or their associative condiments are placed on the trays at each of the work stations. In soiled tray systems, soiled dishes are transported from the cafeteria to the ware-washing area. 
   The conveyor belt disclosed in U.S. Pat. No. 5,052,548 includes a pair of endless belts mounted in the frame for movement along a conveyor path of travel between corresponding upper and lower return flight paths. The drive mechanism of this system allows the return belt path to be positioned above the conveyor bed. The belts are constrained within a box channel on their lower return flight paths remote from the work stations, thereby to maintain a sanitary environment for food tray preparation or soiled trays. 
   Despite the advantages of that system, it is still possible for the conveyor belts to be contaminated with excess food products or bacteria, viruses or the like. While a conventional UV hood arrangement over the conveyor path of these belts would serve to partially decontaminate the belts, it would not be possible to decontaminate all sides of the belts using that system because both sides of the belts are not exposed in the conveyor flight path. Moreover, as with conventional systems, the UV hood arrangement would take up excess space in the useful conveyor flight path. Therefore, conventional UV systems would not be satisfactory for use with this type of conveyor system. 
   OBJECTIVE OF THE INVENTION 
   It is an object of the present invention to provide an improved food service conveyor system with a self-contained UV disinfection system. 
   Another object of the invention is to provide an ultraviolet irradiation system for a food service conveyor system which exposes all sides of the conveyor to UV irradiation. 
   Yet another object of the invention is to provide a food service system with an ultraviolet irradiation system which is relatively simple in construction and easy to manufacture. 
   A further object of the present invention is to provide a food service conveyor system with a self-contained irradiation unit within an enclosure surrounding the drive path section of the conveyor&#39;s path of travel. 
   BRIEF SUMMARY OF THE INVENTION 
   In accordance with an aspect of the present invention, a food service conveyor is provided which includes a frame, a conveyor bed mounted on the frame, and at least one endless conveyor belt moving between upper and lower flight portions. A belt drive unit is provided to supply motive power to the belt, and includes an enclosed housing having an opening therein through which the belt passes. The housing further includes a drive mechanism for the belt consisting of a motor and a plurality of belt pulleys engaged with the belt. The pulleys guide the conveyor belt from one of the upper and lower flight paths to the drive motor, which applies motive power to the belt and then returns it to the other of the flight paths. 
   A UV-C irradiation lamp is positioned in the belt drive housing interposed in the portion of the path of travel of the belt or belts through the housing. In one embodiment of the invention, multiple light sources are positioned in the housing relative to the path of travel of the belts so that all surfaces of the belts are exposed to irradiation, along with the entire interior of the housing as the belts pass therethrough. In addition, the housing may contain a separation panel which will isolate the conveyor belts from the drive mechanism and other structures contained in the housing to avoid contamination of the belts by those structures. 
   The drive housing is also provided with an access opening and a door or panel for selectively opening and closing the housing. A safety switch is provided for deactivating the UV lights when the door is opened or the panel removed. 
   The light sources used in the present invention are similar in shape to tubular fluorescent light bulbs, but produce ultraviolet light. Such light sources or lamps produce UV-C irradiation at a wavelength of about 254 nm, with an intensity of about 142 μw/cm 2 . Preferably, the lights are positioned, as noted above, between the belts within the housing so as to expose all sides thereof. The path of travel of the belts in the drive mechanism, and the number of lights, can be varied so that without changing the size of the housing, there is sufficient an exposure time within the housing to adequately disinfect the belts. Accordingly, the system of the present invention is able to disinfect the belts and the interior of the drive housing in which the belts travel and inactivate common bacteria found in hospital and other institutional air, such as  escherichia coli, pseudomonas, fluoresces, serrapia marcescen, Micrococcus, luteus  and  bacillus subtilis.    
   The above, and other objects, features and advantages of this invention will be apparent in the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings, wherein: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front perspective view of a conveyor system constructed in accordance with the present invention; 
       FIG. 2  is a top plan view of an embodiment of a conveyor frame adapted to be used in the conveyor system of  FIG. 1 ; 
       FIG. 3  is a partial cross-sectional view taken along line  3 — 3  of  FIG. 2 ; 
       FIG. 4  is a front elevational view taken along line  4 — 4  of  FIG. 2  showing the interior of the conveyor bed drive path; 
       FIG. 5  is a side view taken along lines  5 — 5  of  FIG. 4 ; 
       FIG. 6  is a side perspective view of the drive unit and a portion of the conveyor bed shown in  FIG. 1 ; 
       FIG. 7  is a side elevational view with the doors removed to expose the interior of the drive mechanism; 
       FIG. 8  is a side view, in section, of the interior of the drive housing; 
       FIG. 9  is a side view, with the doors removed, of the side of the drive unit seen in  FIG. 7 ; and 
       FIG. 10  is a view similar to  FIG. 4 , showing another embodiment of the invention using a plurality of UV light sources. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring now to the drawings in detail, and initially to  FIG. 1  thereof, a conveyor system  10  constructed in accordance with the present invention includes a frame  12  (typically formed of stainless steel) that defines a conveyor path of travel  14 . The path of travel is of substantial length such as is used in the food service industry to transport food trays  16 , soiled trays, or the like, between different work stations. Although the illustrative embodiment relates to food service conveyor systems, the invention is readily adaptable to other objects, particularly objects which may cause undesirable contamination of the conveyor itself. 
   As seen in  FIG. 3 , the conveyor frame  12  includes a conveyor bed panel  21  which is made of stainless steel and shaped to provide two conveyor beds  22 ,  24  along which the conveyor elements, described hereinafter, move. 
   As seen in  FIG. 1 , a plurality of work stations  17  are provided adjacent to the longitudinal side edges  27   a ,  27   b , of conveyor bed  21 . In food preparation, at each work station a different food or beverage container or food item is placed on each tray as it moves along the conveyor bed. For soiled tray systems, soiled dishes are transported, for example, from the cafeteria area to a ware-washing area. 
   In a food tray preparation system as shown, the work station  17  may include a heated plate dispenser  38 , an ice-cream dispenser  40 , a coffee urn stand  42 , and a mug dispenser  44 . At the forward end  46  of the conveyor there could be a tray dispenser  26 , a heated underliner dispenser  28 , a second heated plate dispenser  30 , a food unit  32 , a beverage dispenser  34 , a cold food unit  36 , and a toaster caddy  37 . In some cases, in order to conserve space, portions of the work stations are positioned underneath the conveyor bed  21 . 
   Referring again to  FIG. 3 , it is seen that the conveyor bed sections  22 ,  24  define the upper flight paths  64   a ,  64   b  for the conveyor elements  76   a ,  76   b . In the illustrative embodiment, the trays  16  sit on these portions of these two conveyor elements in those upper flight paths and are moved thereby as the conveyor passes along the conveyor bed. 
   As seen in  FIG. 1 , the trays move along each conveyor bed from the front end  46  thereof to the discharge or drive end  48 . The tray sides are constrained within the conveyor bed by the retention surfaces  54   a  and  54   b  formed therein. The inner edges  56   a ,  56   b  of the conveyor bed sections  22 ,  24  are joined to a central box channel  68 , which receives the lower or return flight paths of the conveyors elements  76   a ,  76   b.    
   As seen in  FIG. 3 , central box channel  68  is located below the edges  56   a ,  56   b  of the conveyor beds, and define a trough which constrains the conveyor belts  76   a ,  76   b  during their lower return flight paths. 
   The conveyor belts  76   a ,  76   b  move between their corresponding upper and lower return flight paths, as seen in  FIG. 3 , in the manner described in U.S. Pat. No. 5,052,548. Preferably, these belts are circular in cross section, and have approximately a ½ inch diameter, being made of flexible polymeric material. In contrast to conventional chain link conveyor belts, the round belts of the present invention are conveniently removable from the conveyor system and, because they have no corners, are advantageous for food handling systems and trays which are not resistant to substantial wear. 
   At the drive end  48  of the conveyor bed, as seen in  FIG. 1 , the trays are removed from the conveyor bed as the belts pass into a drive enclosure  50  through openings formed in the slanted wall  53  formed in the conveyor bed at the end  48  thereof (See FIG.  5 ). The housing contains a belt drive arrangement or transmission which applies motive power to the belt and returns it to the conveyor bed for return along the lower flight path of the central box channel  68 . 
   The pulley system which guides the conveyor belts  76  between their flight paths is described in detail in U.S. Pat. No. 5,052,548, and that description need not be repeated herein. However,  FIGS. 4 and 5  do show the pulley and drive arrangement in the drive enclosure or cabinet  50 . Included therein is a set of drive pulleys  84  and a belt drive unit  85  mounted in the base of the enclosure or housing  50 . The pulleys  84  are generally in vertical parallel alignment and positioned just below the top  51  of the housing. Apertures or ports formed in the surface  53  allow the belts to pass through the conveyor bed into the interior of the housing to limit contamination entering into the enclosure. The outer pulleys  84   a  and  84   b  receive the belts  76   a  and  76   b  respectively from the upper flight path of the conveyor, and direct the belts to another set of pulleys  87   a  and  87   b  of the belt drive unit  85 . Belts  76   a  and  76   b  are then directed upwardly through the inner pulleys  84   c  and  84   d , which in turn direct the belts to the lower return flight path  70  of the box channel  68  towards the pulley arrangement at the front end  46  of the conveyor flight path. 
   As seen in  FIG. 5 , the central axis  93  of the outer pulleys  84   a  and  84   b  is mounted to be slightly higher than the central axis  92  of the inner drive pulleys  84   c  and  84   d  so that the portions of the belt from the upper flights received by the outer drive pulleys of the portions of the belts returning to the lower flights by the inner drive pulleys will enter the box channel  64  and be located, as seen in  FIG. 3 , at a lower level than the upper flight portions  76   a  and  76   b.    
   As seen in  FIGS. 4 and 7 , the pulleys  87   a  and  87   b  are connected to a speed reducer  91  which is connected between the pulleys  85  and a DC electric motor  92  to drive the conveyor belts. 
   As noted above, the conveyor drive path of travel, illustrated in  FIG. 4 , is contained within a housing  50 . This housing is divided into two sections  95 ,  96 . As seen in  FIGS. 5 and 7 , the section  95  contains the pulleys  84 ,  85 ,  87 , the conveyor drive flight portions of the belts, and the speed reducer  91 . It is separated from the section  96  by a partition  98 . The section  96  contains the electric motor  92  and electrical service connections for the system. 
   The side walls of enclosure  50  have openings  100 ,  102  formed therein, which are closed by pivotally mounted doors or removable panels  104 ,  106 , respectively. These panels provide selective access to the interior of the housing  50  for servicing. They are pivotally or removably mounted in any known or convenient manner. This arrangement gives the operator the option of independently accessing each of the chambers  95 ,  96 , while at the same time keeping the chamber  96  free of contamination from the conveyor belts and free from exposure to the UV lights. 
   In accordance with the present invention, an ultraviolet light source  110  is provided within the chamber  95 . This light source in the embodiment of the invention illustrated in  FIGS. 4 and 7  is a single UV-C irradiation lamp, similar to a fluorescent lamp. The lamp may be of the type which can be mounted only at one end by a conventional socket  112  supported on the central panel  98 , or it can be of the type having two ends, each of which is separately supported on an electrical socket mounted on the central panel  98  and the front wall  114  of the housing  50 . 
   As seen in  FIG. 8 , a power pack and ballast  118  may be mounted on the panel  98  within the chamber  96 , again for servicing. 
   In another embodiment of the present invention, illustrated in  FIG. 10 , three UV-C lighting elements  110  may be provided, as illustrated. In this embodiment, all surfaces of the belts  76  are exposed to irradiation from the lamps  110  to insure complete disinfection thereof. The lamps simultaneously disinfect the air contained within the space  95 . Constructing the enclosure as described, access to the motor chamber  96  of the enclosure can be had by opening its associated door or doors while the conveyor is operating without having the chamber or the individuals working within the chamber exposed to the UV light. 
   On the other hand, chamber  95  is provided with a contact switch  120 , as illustrated in  FIGS. 7 and 9 , so that when the panels covering the openings to that chamber are opened or removed, the lamps will automatically be shut off. Likewise, when the panels are reinstalled or the doors closed, the contact switch is closed so that the lamps are illuminated, providing electrical power is supplied to the system. Moreover, the construction of the enclosure with the compartment and the entry panel  53  described above, essentially conceals the UV lighting from any line of sight. 
   While the present invention has been particularly shown and described with reference to the preferred embodiments, it is understood that various changes and modifications may be affected therein by those skilled in the art without departing from the scope or spirit of the invention.