Abstract:
A chiller comprises a vessel for coolant and an endless conveyor having transverse flights. The conveyor passes in a loop from one side to another of the vessel. An arrangement is provided to alter the path of the conveyor so as to shorten and lengthen the loop. In use, when the loop is lengthened articles are tumbled in the coolant by the flights, and when the loop is shortened articles are conveyed out of the vessel.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to chillers (which may alternatively be referred to as coolers), particularly for bagged food products, of the type in which the bags are made to tumble in a bath of liquid coolant. Liquid or semi-liquid food products, such as soups and sauces, may be packaged after cooking in sealed plastic bags. In order to reduce the temperature of the food product, the bags may be introduced into a tumble chiller consisting of a drum which contains a coolant such as water or brine which is maintained at a temperature of approximately 0° C. The drum rotates about a horizontal axis and serves to tumble the bags in the coolant and thereby promote cooling. After cooling, a door into the drum is opened. Some 20% of the bags fall out on their own, but the remainder must be removed manually.  
           [0002]    An object of the invention is to provide a chiller which enables bags of food product to be introduced into a coolant, tumbled, and then removed after cooling, without manual handling.  
         BRIEF SUMMARY OF THE INVENTION  
         [0003]    In accordance with the invention, a chiller comprises a vessel for containing a liquid coolant, an endless conveyor, means for circulating the conveyor, and means for supporting the conveyor such that a run thereof descends into the vessel to form a loop within a coolant. The means for supporting the conveyor as so defined allow the length of the loop-forming run to be lengthened and shortened, as required. When the run is lengthened it forms a loop of sufficient volume to allow bags of food product to be tumbled in the coolant in which the conveyor run is immersed. In this mode of operation, the angle of the run at each of its ends is so steep that it cannot entrain and remove bags from the coolant. Flights on the conveyor may thereby serve as the means for causing the coolant to circulate and tumble the bags within the confines of the loop. When the loop-forming run is shortened, the loop becomes relatively shallow, and the run may serve to entrain and remove the bags from the coolant.  
           [0004]    In a preferred embodiment of the invention, the loop-forming run passes over spaced-apart rollers, each of which is drivable in opposite directions, and at least one of which is drivable at two speeds at least, so as to allow a differential speed to be established between the two rollers. Rotation of the rollers so as to circulate the conveyor in one direction allows a second run of the conveyor (adjoining the loop-forming run) to be used to transport bags into the vessel during an initial phase of operation, where they accumulate in the space within the loop. Continued circulation of the conveyor may then be used to circulate the coolant and tumble the accumulated bags. Because of the steepness of the ends of the loop, the conveyor cannot entrain and remove the bags during this phase of operation. When the temperature of the bags has been reduced to a desired level, the rollers may be driven at different speeds so as to shorten the length of the run extending between them. When the desired reduction in the length of the run has been achieved, the rollers may again be driven at equal speeds. This reduction in the size of the loop and the gentle slope of the run at its ends during this latter phase allows the conveyor to entrain the bags and carry them out of the vessel. This latter phase of operation may be carried out with the conveyor circulating in the opposite direction to that during the first phase, in which case the bags are removed from the vessel on the same side as that at which they entered it. Alternatively, the latter phase may be carried out with the conveyor circulating in the same direction as during the initial phase, so that the bags are removed from the opposite side of the conveyor to that at which they entered it. Other arrangements may be used to lengthen and shorten the loop-forming run, and are contemplated by the invention. Thus, for example, one of the rollers supporting this run may be movable towards and away from the other roller.  
           [0005]    It will be appreciated that any reduction in the length of the loop-forming run will be accompanied by an increase in the length of another run of the conveyor, so necessitating some means for taking up slack. Conveniently, an hydraulic or pneumatic ram mechanism is provided to support a further roller over which the conveyor passes. As the loop is shortened, the ram is extended to displace the further roller by the appropriate distance and prevent slack forming. Although it is preferred to use the conveyor to cause circulation of the coolant, other means may be used for this purpose and the conveyor used just to load and unload (or even just unload) the chiller. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0006]    [0006]FIG. 1 is a diagrammatic vertical section through a first embodiment of chiller to illustrate operation in the loading and tumbling phases, FIG. 2 is a view similar to FIG. I but illustrating the unloading phase, FIG. 3 is a view similar to FIG. 1 but of a second embodiment during the loading phase. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0007]    Referring to FIG. 1 and FIG. 2 of the drawings, a first embodiment of chiller comprises a substantially semi-cylindrical vessel  2  supported on a frame  3 . The vessel contains coolant conveniently water  4  at 0° C. having a level L. The vessel  2  is provided with dimpled jacket  5  to promote heat exchange with a refrigerant passing through the jacket to maintain the water at this temperature. An endless conveyor  6  has transverse flights  8  projecting therefrom. The conveyor passes around a roller  10 , a roller  12  at one side of the vessel and a roller  14  at the other side of the vessel. The rollers  12  and  14  are journalled in the frame and are driven by independent, reversible electric motors  12   a  and  14   a  both mounted on the frame. Between the rollers  12  and  14  the conveyor falls in an unsupported, hanging loop  16  within vessel  2 . Between rollers  10  and  12  the conveyor passes beneath the vessel. Between the roller  10  and the roller  14 , the conveyor slopes upwardly in a run  18  extending from a bag filling station  22  to the vessel. The roller  10  is supported by a pair of pneumatic or hydraulic rams  16  mounted at one end on the frame.  
         [0008]    A controller  30  (FIG. 2) is provided in the electric circuit  32  for the electric motors  12   a  and  14   a , to selectably drive the rollers  12  and  14  at the same speed, to drive the roller  12  faster than roller  14  or to drive the roller  14  faster than the roller  12 , and to drive the motors in either direction. When the rollers  12  and  14  are driven at the same speed, whatever the length of the loop  16  is, that length is maintained. In the state shown in FIG. 1, the loop  16  is of substantial depth whereas in the state shown in FIG. 2 the loop  16  is relatively shallow. To progress from the state shown in FIG. 1 to that shown in FIG. 2 the trailing roller (considered in the direction of conveyer circulation) must be driven slower than the leading roller. When the transition has taken place, the speed of the rollers  12  and  14  is returned to matching values. To return from the state shown in FIG. 2 to that of FIG. 1, the trailing roller must be driven faster than the leading roller.  
         [0009]    In a first or loading phase of operation, depicted in FIG. 1, the rollers  12  and  14  are driven in rotation so as to cause the conveyor to circulate in a counter-clockwise direction. Bags B are filled with hot food product and sealed at filling station  22  and are loaded onto the run  18 , and conveyed upwardly by engagement with the conveyor flights until they pass over roller  14  and fall into the bath of coolant contained within the loop  16 . In this phase of operation, the ends of the run which constitutes the loop are generally vertical where they meet the rollers  12  and  14 , and the flights are so designed (either in terms of size or flexibility) that they cannot lift the bags out of the vessel over roller  12 . During a succeeding second or tumbling phase the flights cause the coolant to circulate and tumble the bags, or may cause the bags to tumble by making direct contact with them. This tumbling action promotes cooling. It will be appreciated that the first and second phases overlap, the bags being tumbled in the coolant immediately after they enter it.  
         [0010]    When the food product has been cooled to a desired temperature, the rollers are driven in reverse so as to circulate the conveyor in the clockwise direction, with the roller  12  rotating more slowly than roller  14  during a third phase of operation, thereby to shorten the run of the conveyor which constitutes the loop  16 . This results in the loop becoming shallower and its ends becoming less steep. At the same time, the rams  16  are extended so as to take up slack in the remainder of the conveyor. When the position depicted in FIG. 2 is reached, the rollers  12  and  14  are driven at the same speed and during this fourth or unloading phase (and, possibly, to some extent while the loop is being shortened) the conveyor flights (omitted from FIG. 2) entrain the bags and remove them from the vessel along run  18 . Of course, the conveyor may be circulated in the clockwise direction during the second phase after the chiller has been loaded, or it may be circulated alternately in one direction and then the other during the second phase.  
         [0011]    In the embodiment shown in FIG. 3, the arrangement is generally similar to FIGS. 1 and 2 but externally of the vessel the conveyor passes around a series of rollers  10 ,  10   a  and  10   b  and slack in the conveyor is taken up by biasing a roller  10   a  downwards along a track  24  disposed between rollers  10   a . Also, the conveyor continues to be driven in the counter-clockwise direction during all phases so that the bags are lifted out of the vessel at its left hand side and are conveyed away from the chiller along a chute  26  during the unloading phase.  
         [0012]    It will be understood that the rollers  12  and  14  may alternatively be driven from a single source of motive power, gearing being provided to vary the relative speeds of rollers  12  and  14 . The conveyor may be in the form of a continuous belt or, more preferably, assembled from inter-articulated plastics sections which are perforated so as to prevent coolant being carried out of the vessel as the conveyor emerges from it. Other means for changing the length of the loop  16  also fall within the scope of the invention, for example, an arrangement to adjust the position of one of the rollers  12 ,  14  relative to the other.  
         [0013]    Although the invention is preferably carried out using flights extending the width of the conveyor, it falls within the scope of the invention for the conveyor to be provided with any other type of formation which is capable of entraining the bags and introducing them into and removing them from the vessel and producing a tumbling action.  
         [0014]    The rollers may be of any construction suitable for interengaging with the conveyor, and the term “roller” is to be understood to include spaced-apart toothed wheels cooperating with racks on the conveyor, for example. Although it is convenient for the bags to be delivered to the chiller along a run of the conveyor, they may be delivered to the chiller in any other way, for example, by a separate conveyor or down a chute.