Abstract:
A dishwasher is disclosed for the batch-wise washing of wash items. In at least one embodiment, the dishwasher includes a wash chamber, which is arranged to accommodate wash items and in which at least one sprayer for spraying out washing liquid and rinsing liquid are disposed; a wash tank, which is arranged to contain washing liquid which during a wash phase shall be supplied to the wash chamber via the at least one sprayer; a recirculating rinse tank, which is arranged to contain used rinsing liquid which during a rinse phase shall be supplied to the wash chamber via the at least one sprayer; a supplier for supplying final-rinse liquid which during a final-rinse phase shall be supplied to the wash chamber via the at least one sprayer; a collecting device, which is arranged to collect liquid which has been sprayed out into the wash chamber via the at least one sprayer; and a pump, which is arranged to pump used rinsing liquid from the collecting device to the recirculating rinse tank.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a dishwasher for the batch washing of wash items, wherein the dishwasher comprises a wash chamber with spray members for spraying out washing liquid and rinsing liquid; a wash tank for washing liquid; a recirculating rinse tank for used rinsing liquid; members for the supply of final-rinse liquid; and a collecting device, which is arranged to collect liquid which has been sprayed out into the wash chamber via the spray members. The present invention also relates to a process for the rinsing of wash items. 
       TECHNICAL BACKGROUND 
       [0002]    A washing operation for washing soiled wash items, for example kitchen utensils in the form of plates, glasses, cutlery, saucepans, usually comprises the steps: 
         [0003]    washing of the wash items with a detergent-containing washing liquid 
         [0004]    rinsing of the wash items with a rinsing liquid so that residues of the washing liquid, and any food remnants in the washing liquid, shall be rinsed away. 
         [0005]    For an effective rinse, the rinsing liquid is often heated. In addition, it is normal for it to contain a drying agent, which reduces the surface tension of the rinsing liquid and thus makes it easier for the rinsing liquid to run off the wash items after the rinse. The consumption of rinsing liquid, and, where appropriate, of rinsing liquid chemicals such as drying agent, as well as of energy for heating the rinsing liquid, accounts for an appreciable share of the operating costs for a dishwasher. 
         [0006]    WO2005/020782 describes a dishwasher with reduced rinsing liquid consumption. This is achieved by the dishwasher in WO2005/020782 being provided with a collecting device for used rinsing liquid, and with a recirculating rinse tank having an inlet connected to the collecting device. The collected rinsing liquid is used to rinse the wash items in a pre-rinse phase, whereafter a final rinse of the wash items is realized with new, clean final-rinse liquid in a final-rinse phase. A float valve with delayed opening ensures that the very first pre-rinse liquid, which is dirtiest, is not allowed to enter the recirculating rinse tank, but instead runs down into the wash tank. 
       SUMMARY OF THE INVENTION 
       [0007]    One object of the invention is to reduce the consumption of rinsing liquid. This object is achieved with the aid of a dishwasher for the batch washing of wash items, the dishwasher comprising a wash chamber, which is arranged to accommodate wash items and in which spray members for spraying out washing liquid and rinsing liquid are disposed; a wash tank, which is arranged to contain washing liquid which during a wash phase shall be supplied to the wash chamber via the spray members; a recirculating rinse tank, which is arranged to contain used rinsing liquid which during a rinse phase shall be supplied to the wash chamber via the spray members; members for the supply of final-rinse liquid which during a final-rinse phase shall be supplied to the wash chamber via the spray members; a collecting device, which is arranged to collect liquid which has been sprayed out into the wash chamber via the spray members; and a pump, which is arranged to pump used rinsing liquid from the collecting device to the recirculating rinse tank. By virtue of the fact that a pump is arranged to pump used rinsing liquid from the collecting device to the recirculating rinse tank, it is possible to relinquish an accurately controllable quantity of first rinsing liquid. The reused rinsing liquid can hence be kept cleaner, so that it is sufficient to supply a lesser quantity of clean final-rinse liquid. The quantity of rinsing liquid which is relinquished can also easily be varied in dependence on the chosen wash program, the number of dishes for which the washing liquid in the wash tank has been used, etc. By virtue of the invention, it is also possible to, with greater accuracy, clear space in the recirculating rinse tank for the final-rinse liquid, which reduces the risk of some of the collected final-rinse liquid being deprived of space in the recirculating rinse tank. This too helps to keep the reused rinsing liquid cleaner. All in all, the invention saves on rinsing liquid, as well as, where appropriate, on heating energy and rinsing liquid chemicals, for example drying agent. This implies, of course, both economic and environmental advantages. The advantages of the invention can also, of course, be realized in the form of a better wash result, i.e. cleaner dishes, instead of, or in combination with, the above-stated economic and environmental savings. 
         [0008]    In one embodiment, the dishwasher is arranged to begin pumping used rinsing liquid from the collecting device to the recirculating rinse tank after the wash items have been rinsed with rinsing liquid from the recirculating rinse tank for at least 3 seconds. This has proved to be a suitable rough-rinsing time for the dirtiest washing liquid to manage to be rinsed properly out of the wash chamber. 
         [0009]    In one embodiment, the wash tank is situated beneath the wash chamber, and the collecting device comprises a collecting plate, which is inclined relative to a horizontal plane and which forms a lower limit surface for the wash chamber and is provided with an opening via which the wash chamber communicates with the wash tank, the wash tank being arranged to receive used washing liquid and rinsing liquid from the wash chamber via the collecting device and the said opening. This embodiment can be realized with few moving parts, and the fact that the, relatively speaking, cleaner rinsing liquid is allowed to dilute the, relatively speaking, dirtier washing liquid enables the washing operation to be shortened and/or rinsing liquid saved. Preferably, the collecting device comprises a trough extending along the periphery of the opening and the pump is connected to an outlet, disposed in the trough, for used rinsing liquid. This embodiment produces an effective collection with few moving parts. Preferably, the trough is inclined relative to the horizontal plane and the outlet of the trough is situated in the lowest portion of the trough. A greater recirculating flow can thereby be achieved. 
         [0010]    In one embodiment, the recirculating rinse tank is provided with an overflow for rinsing liquid. Hence it is always possible to pump the last, and therefore cleanest, rinsing water into the recirculating rinse tank, regardless of how full it is. Preferably, the overflow for rinsing liquid emerges in or above the wash tank. The rinsing liquid is hence reused as washing liquid. 
         [0011]    In one embodiment, the recirculating rinse tank is provided with a liquid level sensor. Such a sensor makes it easier to adjust the quantity of final-rinse liquid in a final-rinse phase to the space in the recirculating rinse tank, and vice versa. 
         [0012]    In one embodiment, the wash chamber is delimited at the top by a raisable and lowerable hood. 
         [0013]    According to another aspect of the invention, the object is achieved with the aid of a process for the batch rinsing of washed wash items in a wash chamber in a dishwasher, wherein the process comprises rinsing of the wash items with used rinsing liquid from a recirculating rinse tank in a rough-rinse phase; rinsing of the wash items with used rinsing liquid from a recirculating rinse tank in a recirculating rinse phase; rinsing of the wash items with final-rinse liquid in a final-rinse phase; and collection of rinsing liquid used in the recirculating rinse phase and the final-rinse phase, the process comprising the pumping of collected rinsing liquid to the recirculating rinse tank. As a result of this process, it is possible to relinquish an accurately controllable quantity of the first rinsing liquid which is used in the rough-rinse phase. The reused rinsing liquid can hence be kept cleaner, so that it is sufficient to supply a lesser quantity of clean final-rinse liquid. By virtue of the invention, it is also possible to, with greater accuracy, clear space in the recirculating rinse tank for the final-rinse liquid, which reduces the risk of some of the collected final-rinse liquid being deprived of space in the recirculating rinse tank. This too helps to keep the reused final-rinse liquid cleaner. All in all, the invention saves on rinsing liquid, as well as, where appropriate, on heating energy and rinsing liquid chemicals, for example drying agent. Preferably, the pumping of collected rinsing liquid is begun no sooner than at least three seconds after the commencement of the rough-rinse phase. 
         [0014]    In one embodiment, the rinsing water used in the rough-rinse phase is led to a wash tank. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The invention will be described in greater detail below with the aid of a preferred, but non-limiting embodiment and with reference to the appended drawings. 
           [0016]      FIG. 1  is a schematic side view of a dishwasher. 
           [0017]      FIG. 2  is a sectional view of the dishwasher in  FIG. 1 . 
           [0018]      FIG. 3  is a view of the section III-III in  FIG. 2 . 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0019]      FIG. 1  shows an example of an embodiment of a dishwasher for the washing and rinsing of wash items. The dishwasher  10  has a frame  12 , which is provided with lips  14  ( FIG. 2 ) arranged to support a wash basket  16  of standard 500 mm width. A raisable and lowerable hood  18  is arranged to, in raised position (unbroken line), allow the wash basket  16  containing soiled wash items  20  to be introduced into the machine  10  via a hood gap  22  and placed on the lips  14 . In the lowered position (dashed line), the hood  18  is arranged to shut tight against the frame  12 , and thereby form a closed wash chamber  24  ( FIG. 2 ). The hood  18  is arranged to be raised and lowered with a control member  26 . 
         [0020]      FIG. 2  is a sectional view of the dishwasher  10 . The machine  10  is shown with the hood  18  in the lowered position. The frame  12  comprises a wash tank  28 , which contains washing liquid in the form of, for example, water mixed with detergent, up to a level determined by an overflow pipe  30 . The overflow pipe  30  is connected to a drain  32  in a non-illustrated manner. 
         [0021]    An upper horizontal spraying arm  34   a  is situated on an upper part of the frame  12 , and is rotatable about a substantially vertical axis  36   a . The upper spraying arm  34   a  is provided with a plurality of nozzles (not shown), which are directed downwards to spray out washing and rinsing liquid towards the wash items  20  from above. A lower horizontal spraying arm  34   b  is situated beneath the lips  14 , and it too is rotatable about a substantially vertical axis  36   b . The lower horizontal spraying arm  34   b  is provided with a plurality of nozzles  38   b  ( FIG. 3 ), which are directed upwards to spray out washing and rinsing liquid towards the wash items  20  from below. A wash pump  40  is arranged to pump washing liquid from the wash tank  28  to the spraying arms  34   a - b . In the bottom of the wash tank  28  is found a bottom valve (not shown), which is connected to the drain  32  for emptying of the wash tank  28 , for example at the end of the working day or when it is wished to clean or service the machine  10 . 
         [0022]    A collecting plate  42 , for collecting washing and rinsing liquid which has been sprayed out from the spraying arms  34   a - b , covers the majority of the bottom of the wash chamber  24 , and inclines downwards towards an opening  44  ( FIG. 3 ) in the collecting plate  42 , through which opening  44  the wash chamber  24  communicates with the wash tank  28 . Running around the opening  44  is a collecting trough  46  with sloping bottom. A recovery pump  48  for used rinsing liquid is connected to a rinsing liquid outlet  50  at the lowest point of the collecting trough  46 . The recovery pump  48  is arranged to not be activated during the washing of the wash items  20 . The washing liquid which during a wash phase is sprayed out into the wash chamber  24  by means of the spraying arms  34   a - b  will hence be collected by the collecting plate  42 , spill over the collecting trough  46 , and run down into the wash tank  28  via the opening  44 . 
         [0023]    The recovery pump  48  is arranged to, when activated, pump liquid from the outlet  50  of the collecting trough  46  to a circular-cylindrical recirculating rinse tank  52 , which is situated in the wash tank  28 . The recirculating rinse tank  52  is delimited by a wall  54 , which extends up above the overflow  30  of the wash tank  28 . In addition, the recirculating rinse tank  52  is provided at the top with an opening  56 , so that rinsing liquid can spill over the upper edge of the wall  54  and run out into the wash tank. The opening  56  is covered by a cap  58 , which allows overspill from the recirculating rinse tank  52  down into the wash tank  28 , at the same time as it prevents liquid from the wash chamber  24  from being washed down into the recirculating rinse tank  52  from above. 
         [0024]    A recirculating rinse pump  60  is arranged to pump used rinsing liquid from the recirculating rinse tank  52  to the spraying arms  34   a - b . In addition, the dishwasher  10  is provided with an inlet  62  for clean final-rinse liquid, and a final-rinse pump (not shown) for pumping the clean final-rinse liquid to the spraying arms  34   a - b  during a final-rinse phase. 
         [0025]    The outlet  64  of the recovery pump  48  emerges in an upper portion of the recirculating rinse tank  52 , and the inlet  66  of the recirculating rinse pump  60  emerges in a lower portion of the recirculating rinse tank  52 . The last collected rinsing liquid will hence be that which is last pumped to the spraying arms  34   a - b  with the recirculating rinse pump  60 . This means that the very last used final-rinse liquid, which also is cleanest, will not be sprayed out from the spraying arms  34   a - b  during a first rough-rinse phase in a next washing operation, but is saved for a recirculating rinse phase, and thus is at least partially recovered. 
         [0026]    An alternative embodiment would be to have the outlet of the recovery pump  48  emerge in a lower portion of the recirculating rinse tank  52 , and to have the inlet of the recirculating rinse pump  60  emerge in an upper portion of the recirculating rinse tank  52 . This embodiment means, on the one hand, that a minimum of the last recovered rinsing liquid is lost in the event of any overflowing of the recirculating rinse tank  52 , yet, on the other hand, that it is necessary to ensure that there is a sufficient quantity of rinsing liquid present in the recirculating rinse tank  52  during the rough-rinse and recirculating rinse phases. 
         [0027]    The recirculating rinse tank is further provided with a liquid level sensor (not shown) for measuring the quantity of rinsing liquid in the recirculating rinse tank. The quantity of final-rinse liquid which is sprayed out via the spraying arms  34   a - b  in a final-rinse phase can hence easily be adjusted to the vacant space in the recirculating rinse tank  52 , so that none or only a little of the collected, relatively clean final-rinse liquid spills over the recirculating rinse tank  52  and down into the wash tank  28 . Conversely, the liquid level sensor can also be used, during a recirculating rinse phase, to provide adequate space in the recirculating rinse tank  52  for a certain predetermined quantity of used final-rinse liquid for collection in a final-rinse phase. 
         [0028]    The dishwasher  10  can also be provided with a filter (not shown) in the opening  44  between the wash chamber  24  and the wash tank  28 . Any food remnants in the washing liquid can hence be collected and removed effectively. 
         [0029]      FIG. 3  is a view of the section III-III in  FIG. 2 . For reasons of clarity, the wash basket  16  and the wash items  20  are not shown. The view shows the lips  14 , the lower spraying arm  34   b , the collecting plate  42 , the opening  44 , the collecting trough  46 , the outlet  50  of the trough  46 , and the cap  58  over the recirculating tank  52  (dashed). 
         [0030]    The dishwasher in  FIGS. 1-3  is arranged to execute a washing operation as follows: 
         [0031]    First the wash items are washed in a wash phase, during which washing liquid is pumped from the wash tank  28  to the spraying arms  34   a - b  with the aid of the wash pump  40 . The washing liquid is sprayed onto the wash items  20  with the aid of the spraying arms  34   a - b  and is subsequently allowed to run back down into the wash tank  28  via the collecting trough  46 , which overflows. The wash phase continues for about 90 seconds; during this time, washing liquid circulates between the wash chamber  24  and the wash tank  28 . 
         [0032]    The wash phase is followed by a short pause of about 8 seconds to allow washing liquid to run off the wash items. 
         [0033]    After this, the wash items  20  are rinsed in a rough-rinse phase, during which used rinsing liquid from the recirculating rinse tank  52  is pumped to the spraying arms  34   a - b  with the aid of the recirculating rinse pump  60 . The rinsing liquid from the recirculating rinse tank  52  is sprayed onto the wash items  20  with the aid of the spraying arms  34   a - b  and is subsequently allowed to run down into the wash tank  28  via the collecting trough  46 , which overflows. The rinsing liquid which is used during the rough-rinse phase will rinse most of the wash water remaining in the wash chamber  24  and the collecting trough  46  down into the wash tank  28 . The rough-rinse phase continues for about 5 seconds. 
         [0034]    There then follows a recirculating rinse phase, during which used rinsing liquid from the recirculating rinse tank  52  is pumped to the spraying arms  34   a - b  with the aid of the recirculating rinse pump  60 . The rinsing liquid from the recirculating rinse tank  52  is sprayed onto the wash items  20  with the aid of the spraying arms  34   a - b  and is subsequently led via the collecting plate  42  to the collecting trough  46 . The recovery pump  48  is active during the recirculating rinse phase and pumps back collected, used rinsing liquid from the collecting trough  46  to the recirculating rinse tank  52 . A certain quantity of rinsing liquid can also run from the wash chamber  24  down into the wash tank  28  via the opening  44 . 
         [0035]    During a final-rinse phase, clean final-rinse liquid is pumped from the inlet  62  for final-rinse liquid to the spraying arms  34   a - b  with the aid of the final-rinse pump (not shown). The rinsing liquid from the inlet  62  is sprayed onto the wash items  20  with the aid of the spraying arms  34   a - b  and is subsequently led via the collecting plate  42  to the collecting trough  46 . The recovery pump  48  is active during the final-rinse phase and pumps collected, used final-rinse liquid from the collecting trough  46  to the recirculating rinse tank  52 . 
         [0036]    The recovery pump  48  is arranged to be active for about 10 more seconds following the conclusion of the final-rinse. Hence, the last, clean final-rinse liquid which runs off the wash items  20  after the final-rinse is also recovered. 
         [0037]    The first rinsing liquid which is used in the rough-rinse phase will be mixed during the rough-rinse with the dirty washing liquid remaining on the wash items  20  and in the collecting trough  46 . The inactivity of the recovery pump  48  during the rough-rinse phase means that this first rinsing liquid is not recovered, but is instead allowed to dilute the washing liquid. A certain quantity of detergent should therefore be added to the washing liquid prior to the next washing operation to compensate for the dilution. 
         [0038]    To sum up, a dishwasher with a recirculating rinse tank has been described above, wherein the dishwasher is arranged to execute a washing operation comprising at least the following phases:
       a wash phase, in which washing liquid bathes the wash items;   a rough-rinse phase, during which used rinsing liquid from the recirculating rinse tank bathes the wash items, but is not returned to the recirculating rinse tank;   a recirculating rinse phase, during which used rinsing liquid from the recirculating rinse tank bathes the wash items, is collected and pumped to the recirculating rinse tank; and   a final-rinse phase, in which the final-rinse liquid bathes the wash items, is collected and pumped to the recirculating rinse tank.       
 
         [0043]    It will be appreciated that the invention can be variously modified within the scope of the patent claims. For example, it is not necessary that the member for supplying final-rinse liquid shall comprise a connection on the outer side of the dishwasher  10 . The member for supplying final-rinse liquid can equally well comprise a tank for final-rinse liquid inside the machine; this tank can be arranged to be filled up arbitrarily at any time prior to, during or after a final-rinse, and the machine can be arranged to automatically supply chemical additives and heat to the rinsing liquid in this tank. 
         [0044]    Even though the spray members in the shown example are used for both washing and rinsing liquid, it is possible, of course, to have separate spray members for washing liquid and rinsing liquid. The dishwasher can also, for example, be provided with separate spray members for used rinsing liquid and final-rinse liquid. 
         [0045]    Nor is it necessary for the wash chamber  14  to be delimited by a raisable and lowerable hood; the dishwasher can equally well be of the front-loaded type.