Abstract:
The invention relates to a method for separating solid particles from a liquid in a dish-washer. For the separation a filter ( 19 ) of expanded metal is provided, which forms openings ( 21 ) the bounding surfaces ( 22 ) of which are inclined in relation to the plane of the filter. The liquid with particles entrained therein is directed towards descending bounding surfaces in the filter for guiding the liquid flow through the filter under separation of the particles from the liquid.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the invention  
           [0002]    The present invention relates to a method for separating solid particles from a liquid in a dish-washer.  
           [0003]    The invention is proposed primarily for a granule dish-washer with a condenser in order to separate granules from the condensation water  
           [0004]    However, the method according to the invention can be applied also to the separation of food residues from circulating liquid in a dish-washer in order to facilitate the cleaning of a filter used for this separation.  
           [0005]    2. Problem involved  
           [0006]    Granules which during a previous dish washing step have collected in the condenser may be carried along by the condensation water to the drain and eventually may clog the filter and as a consequence thereof prevent the outflow of the condensation water.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    The purpose of the invention is to provide a method of the kind referred to above wherein granules entrained in the condensation water are returned to the liquid tank for use in following dishwashing operations.  
           [0008]    For this purpose the invention provides a method for separating solid particles from a liquid in a dish-washer, wherein there is provided for said separation a filter of expanded metal which forms openings the bounding surfaces of which are inclined in relation to the plane of the filter, and wherein the liquid with particles entrained therein is directed towards descending bounding surfaces in the filter for guiding the liquid flow through the filter under separation of the particles from the liquid. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0009]    Embodiments of the invention will be described in order to explain the invention in more detail, reference being made to the accompanying drawing in which  
         [0010]    [0010]FIG. 1 is a diagrammatic side view of a granule dishwasher,  
         [0011]    [0011]FIG. 2 is a perspective view of a condenser in the dish-washer,  
         [0012]    [0012]FIG. 3 is an enlarged fragmentary plan view of a filter consisting of expanded metal and mounted in the condenser,  
         [0013]    [0013]FIG. 4 is a cross sectional view along line IV-IV in FIG. 3,  
         [0014]    [0014]FIG. 5 is a diagrammatic view illustrating the function of the filter consisting of expanded metal, and  
         [0015]    [0015]FIG. 6 is a diagram disclosing the dishwashing cycle in the granule dish-washer. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    [0016]FIG. 1 discloses diagrammatically a granule dish-washer which in a typical embodiment comprises a cabinet  10  for receiving the goods  11  to be cleaned. A number of spray nozzles  12  are provided in the cabinet, and the lower portion of the cabinet forms a liquid tank  13 . On the outside of the cabinet a condenser  14  is mounted which is permanently connected with the interior of the cabinet by upper and lower sleeve couplings  15 ,  16 . The condenser has a connection  17  for supply of cooling water at the top and a closable outlet  18  connected to the lower sleeve coupling  16  for draining off cooling water at the bottom via a filter  19  mounted in the sleeve coupling  11 . The filter slopes downwards towards the mouth of the sleeve coupling  16 . The central portion  20  of the condenser forms a venturi tube for producing an injection effect in the condenser while cooling water is being supplied through the connection  17 .  
         [0017]    The filter  19  consists of expanded metal according to FIGS. 3 and 4, i.e. a close-meshed net with openings  21 , which is made by tensioning (expanding) a slotted metal sheet. The openings  21  are defined by bounding surfaces  22  which are inclined in relation to the plane of the filter as will be seen in FIG. 4. The filter is mounted in the sleeve coupling  16  in such a way that liquid which enters the coupling  16  from the condenser meets descending bounding surfaces  22  of the filter as will be seen in FIG. 5 wherein liquid arriving from the condenser is indicated by arrows  23 .  
         [0018]    A dishwashing cycle in a granule dish-washer is illustrated in FIG. 6 wherein the several steps are marked on a time axis. In a first step  24 , the dish washing step, liquid at about 65° C. together with granules is pumped from the tank  13  to the nozzles  12 , and the jets emanating therefrom are directed towards the goods  11  to be washed, and then the liquid and accompanying granules are returned to the tank in order to be circulated again in the manner described.  
         [0019]    In the second step  25  the granules are separated from the liquid and only liquid at 65° C. is circulated in order to rinse the goods. Then, a final rinsing step  26  with clean water at 85° C. is initiated in order to heat and disinfect the goods, and this water is allowed to flow into the tank  13  in order to be mixed with the liquid therein the volume of which as a consequence thereof will increase existing surplus being drained off to an outlet conduit via an overflow carrying away solid particles, grease etc. from the surface layer in the tank.  
         [0020]    During dish washing and rinsing liquid and granules will enter the condenser  14  because the condenser is permanently connected with the interior of the cabinet, an insignificant amount of liquid being collected in the sleeve coupling  16  below the filter  19  because the outlet  18  is kept closed during these operations. Moreover, some granules adhere to the walls of the condenser by the surface tension of the liquid.  
         [0021]    When the final rinsing step  26  has been terminated the machine in its entirety is warm inside and also the goods that has been cleaned is warm. The interior of the cabinet is filled with hot steam. This must be removed before the cabinet is opened for removing the goods, which is effected in a following step  27  by cooling water being sprayed into the condenser  14  at the connection  17  and being allowed to pass through the condenser to the sleeve coupling  16  where the water is drained off through the outlet conduit  18  now open. At the passage through the venturi tube  20  of the condenser the cooling water provides an injector effect generating a suction through the condenser so that steam is sucked from the interior of the cabinet into the condenser through the sleeve coupling  15 . When moving downwards through the condenser the steam will condense. The condensate is drained off together with the cooling water through the conduit  18 . Granules which during the dish washing and rinsing steps  24 ,  25 ,  26  due to surface tension of the liquid have adhered to the surfaces in the condenser may be entrained in the condensation water, and it is of course desired to retrieve these granules for use in following dish washing cycles. Therefore, they are prevented from being carried along by the water to the outlet  18  by the filter  19  the openings of which are sufficiently small in order that the granules cannot pass therethrough. The water hits the filter from the left as seen in FIGS. 4 and 5 so that it rams the descending inclined bounding surfaces of the filter openings  21  in order to be guided through the openings of the filter and be drained off through the outlet  18  while accompanying granules as well as the granules which have collected on the filter during previous operations will be repelled towards the interior of the cabinet as illustrated in FIG. 5 in order to be received by the tank  18  for reuse in following dish washing steps.  
         [0022]    In the embodiment described the filter of expanded metal is mounted in connection with a condenser but it can also be mounted in the circulation system of the granule dish-washer in order to separate granules from liquid circulating in step  24  with granules entrained therein. In that case the filter can be mounted in inclined position in a conduit for the liquid with granules entrained therein so that granules trapped by the filter will roll from the filter through a side outlet connecting to the filter surface, into a drained collection container while the liquid separated from granules passes through the filter and continues to circulate for effecting rinsing with liquid, step  25 . The separated granules can then be returned to the liquid for reuse in the dish washing step  24 .  
         [0023]    A filter of expanded metal preferably is provided also in the overflow from the tank  13  in the dish-washer the outflow from the tank being directed towards the descending bounding surfaces of the filter in the manner described above. Solid particles such as food residues which are separated from the liquid by means of the filter and collect on the surface thereof then can be easily removed from the filter by rinsing the filter with liquid in a direction opposite to that of the outflow from the tank such that this rinsing flow hits the ascending surfaces of the filter. As a consequence thereof the rinsing flow will have a component directed from the surface of the filter, which lifts collected material from the surface of the filter so that the rinsing flow more easily removes the material from the filter.