EP0178202A1 - Dish washer with a microfilter for the liquid - Google Patents

Abstract

1. A dish washer provided with means for performing microfiltration of the liquid, during all of the washing and rinsing cycles, such filtration being carried out on a liquid current flowing through an element (27) with a fine mesh as a microfilter (29), such means further causing, at the end of the washing and rinsing cycles, an emptying of the liquid with or without a short refilling operation with liquid followed by a short emptying operation, and with means making it possible to create a reverse current through the microfilter (2) and to evacuate to the outside this liquid and the microdebris retained by the microfilter, characterized in that said washing machine also comprises means making it possible to perform, in addition to the usual emptying operations at the end of the washing and rinsing cycles, one or more short intermediate emptying operations performed during all of the washing and rinsing cycles with a view to ensuring an efficient clearance of the said microfilter (29).

Description

The present invention relates to a liquid microfiltration dishwasher.

A dishwasher usually includes a filter designed to separate the waste removed from the dishes, the washing and rinsing liquid of the latter.

This filter is often placed in the tank of the machine, between the underside of the lowest spray arm and the inlet of the spray or rinsing liquid recycling pump. The washing or rinsing liquid falling from the dish baskets, passes through this filter under the effect of gravity before reaching the inlet of this watering or recycling liquid pump and the majority of the waste being in this liquid is retained by this filter. The filtered liquid is again discharged by this sprinkler or recycling pump, into the spray arms of the machine and projected onto the dishes in the dish baskets to clean them, and a new cycle of circulation of the liquid begins again. At the end of a wash or a rinse, the liquid is evacuated by a drain pump. Until now, known dishwashers make it possible to obtain clean dishes in each of their operating programs with a relatively large predetermined quantity of water admitted for the washing and rinsing phases.

It has been found that in such machines, when the volumes of water admitted for the washing and rinsing phases are reduced, consequently the corresponding volumes of washing and rinsing liquid, the dishes cleaned, leaving the machines are dirty, usually covered with small waste or micro-waste. The latter probably passed through the filter used in the machines and remained in suspension in the liquid of the last rinse.

Another observation made is that in such machines, when the filter used having a given mesh size is replaced by a filter having finer meshes to separate micro-waste from the washing or rinsing liquid, the dishes taken out of the machines after washing remain dirty. Indeed, the waste retained by the fine mesh filter impedes the passage of the liquid and the flow of washing liquid becomes insufficient to carry out a correct cleaning of the dishes. In addition, the micro-waste floating in the washing and rinsing liquids is not easily removed during the emptying and these often remain in the liquid of the last rinse and soil the dishes.

French patent application No. 84.00892 has provided a solution to the above problem relating to micro-waste in the dishwasher.

According to French patent application No. 84.00892, a dishwasher comprises in its tub during the washing and rinsing cycles of the dishes, on the one hand, for a microfiltration of micro-waste a stream of liquid passing through a microfilter, created by a drain pump which turns in a direction opposite to that allowing a discharge of the liquid towards the outside of the machine, and on the other hand, for a filtering of large and medium waste a stream of liquid passing through a standard medium filter, created by a recycling pump, and at the end of the washing and rinsing cycles of the dishes, a draining of the liquid from its tank by this drain pump which sucks liquid both through the microfilter and its inlet opening , discharges it towards the outside of the machine at the same time as the micro-waste found in this microfilter and makes it clean. _Jo

A statement made for the first time is that in the machine of French patent application N ° 84.00892, the cleaning or unclogging of the microfilter is done only at the end of the washing or rinsing cycles, by a stream of drained draining liquid by the drain pump through this microfilter loaded with micro-waste and in the opposite direction to the current of liquid subjected to microfiltration, that the clogging of this microfilter is rapid during the washing and rinsing cycles and that this clogging hinders the passage of the microfilter by the flow of liquid subjected to the microphone filtering and even prevents this microfiltration, and that the dishes washed in such a case remain dirty or have insufficient cleanliness.

The object of the present invention, with the aim of avoiding these drawbacks, is to produce an economical dishwasher in which the microfiltration of the liquid in its tank remains effective throughout the duration of the washing and rinsing cycles.

According to the invention, a dishwasher provided during washing and rinsing cycles with liquid microfiltration by a current of liquid passing through a microfilter, created by a drain pump rotating in a direction opposite to that allowing a discharge of liquid outside the machine, and a filtering of large and medium waste, by a stream of liquid passing through a standard filter, created by a recycling pump and at the end of the washing and rinsing cycles of a draining of the liquid by this drain pump which creates a reverse current of the liquid through this microfilter and its intake opening and discharges this liquid and the micro-waste retained by this microfilter to the outside, is characterized in that it comprises in its operation during the washing and rinsing cycles, in addition to the usual oil changes at the end of these cycles, one or more brief intermediate oil changes.

• - la figure 1 représente une vue en perspective schématique et partielle d'un lave-vaisselle réalisé selon l'invention,
• - la figure 2 représente à une autre échelle, une vue schématique en perspective et en coupe partielle de la partie inférieure de la cuve du lave-vaisselle de la figure 1,
• - la figure 3 représente, à une autre échelle, une vue éclatée des filtres du dispositif de filtrage monté dans la partie inférieure de la cuve montrée dans la figure 2, et
• - la figure 4 représente à une autre échelle, une vue partielle, du circuit de la pompe de vidange du lave-vaisselle de la figure 1.

To better understand the invention, a number of embodiments are described below, illustrated by the appended drawings, including:

• FIG. 1 represents a schematic and partial perspective view of a dishwasher produced according to the invention,
• FIG. 2 represents, on another scale, a schematic perspective view and in partial section of the lower part of the tank of the dishwasher of FIG. 1,
• FIG. 3 represents, on another scale, an exploded view of the filters of the filtering device mounted in the lower part of the tank shown in FIG. 2, and
• - Figure 4 shows on another scale, a partial view, of the circuit of the drain pump of the dishwasher of Figure 1.

A dishwasher 1 produced according to the invention and illustrated in the Figures 1 and 2 includes outside, a body 2, and inside, a tank 3 in which are mainly mounted dish baskets 4 and 5, sprinklers 6 and 7, a pumping device 8 , on the one hand, means carrying out standard simultaneous filtering of all of the liquid to rid it of large and medium waste and, on the other hand, means carrying out progressive micro-filtration of this liquid to rid it of micro-waste or low-level waste dimension.

The pumping device 8 comprises in the example illustrated on the one hand a pump 10 intended for recycling of liquid which consists in sucking up liquid accumulated in the bottom of the tank 3 and in discharging it into the sprinkler reels 6 and 7 which spray liquid on the dishes to clean or rinse them and on the other hand a pump 11 intended for the emptying of the dishwasher 1, in other words the evacuation of the liquid and a motor 12 with two directions of rotation ensuring a drive of these two pumps, the wheels of which are fixed to a common shaft 13.

The recycling pump 10 is a pump of the centrifugal type. This pump 10 comprises a body 14, a impeller 15, an inlet opening 16 and a discharge line 17 extended by hydraulic circuits from the dishwasher 1 to the sprinkler reels 6 and 7. The drain pump 11 is a vane type pump which comprises a body 18, an intake opening 19, an intake pipe 20, a chamber 21, a vane wheel 22 which is fixed on the same shaft 13 as that of the wheel 15 thread the centrifugal pump, a discharge line 23 and a non-return valve 24.

The intake opening 19 of the drain pump 11 and the intake manifold 16 of the pump 10 open into the same space 25 formed in the lowest part of the bottom of the tank 3 and which is located between the two pumps 10 and 11. The common shaft 13 of the wheels 15 and 22 of the two pumps 10 and 11 is mounted through this space 25.

The wheels 15 and 22 of the two pumps can have shafts independent and be driven by independent motors rotating in both directions, not shown, or the two pumps 10 and II may be equivalent pumps of another known type than those described above, without departing from the scope of the present invention .

In the dishwasher 1, the means carrying out standard filtering of the liquid and the means carrying out microfiltration are constituted by a filtering device 9 of liquid which comprises at least two independent filters, one of which is an average filter carrying out standard filtering which rids or separates this liquid, large and medium waste and the other a microfilter used to rid or separate the liquid from the maximum of micro-waste or small size waste which have passed through the medium filter. The means carrying out standard filtering can comprise either a medium filter or a coarse filter for ridding or separating this liquid from large waste and a medium filter for ridding or separating this liquid from large and medium waste. A coarse filter is a filter having large meshes of the order of 5 millimeters, a medium filter is a filter having medium meshes of the order of one millimeter and a microfilter is a filter having fine meshes of the order of a few tenths of a millimeter, for example two tenths of a millimeter.

The microfilter is placed in communication with the drain pump through a fraction of the surface of the intake opening thereof. As a result, the liquid entering the drain pump 11 is emptied both through the intake opening of this pump, through the microfilter and through the passage opening for the shaft of this pump.

In the dishwasher, microfiltration is preferably intended for filtering liquid which is already subjected to filtering with a medium filter.

In the dishwasher tank, during the washing or rinsing of the dishes, two independent streams of liquid are created to filter it. One of these liquid streams flows through the medium filter to get rid of large and medium waste, and the other liquid stream passes through the microfilter to free itself from micro-waste. The liquid stream passing through the medium filter is preferably created by the recycling pump while the liquid stream passing through the microfilter is preferably created by the drain pump.

In the example illustrated in FIGS. 2 and 3, the filtering device 9 comprises a medium filter 26, a coarse filter 28 and a microfilter 29. The filtering device 9 is mounted in the lower part of the tank 3 under the reel lower watering hose or the lower reel 6 to completely separate the inlets or inlets 16 and 19 from the pumps, washing or rinsing liquid which has fallen from the dishes, so that all the recycling liquid cannot be admitted into the recycling pump 10 only after having been disposed of its large or medium-sized waste and progressively with its micro-waste. This liquid is then discharged by the recycling pump 10 into the watering reels 6-7 and sprayed from these reels onto the dishes to clean or rinse them before falling back to the bottom 3 of the tank for a new filtering, and a new liquid cycle.

The medium filter 26 can be removable or fixed and have a flat or slightly conical active surface. The medium filter 26 comprises in its active surface a depression 31 for receiving a removable assembly 32 consisting of a microfilter 29, and a coarse filter 28. This coarse filter or drain filter 28 comprises a receptacle 34 whose bottom is a large mesh element. The receptacle 34 of the large filter 28 is itself housed in a well 35 arranged in one end of the depression 31. This well 35 is in direct and exclusive communication with the inlet opening 19 of the drain pump. The coarse filter 28 is intended to retain coarse waste which could hamper the operation of the drain pump 11. The microfilter 29 comprises a microfiltration pot 33 consisting of a closed box provided with an inlet pipe 36, including at at least a portion of the wall consists of an element to very fine mesh 27. In the example illustrated, the upper wall of the microfilter pot consists of the fine mesh element 27 of the order of a few tenths of a millimeter, for example two tenths of a millimeter, while the side walls and bottom are solid walls, and the inlet tube 36 communicates the microfiltration pot 33 with the outside. This inlet manifold 36 has its free end 37 facing downwards, so that when the removable assembly 32 is placed in the depression 31 of the medium filter 26 which is already mounted in the bottom of the tank 3 , this free end 37 of the inlet pipe 36 covers and encloses a connection pipe 38 of a liquid guide channel 39 formed in the opening 19 and the intake pipe 20 of the drain pump 11.

In the dishwasher 1, the drain pump 11 during washing and rinsing rotates in one direction to suck the liquid located in the bottom 25 of the tank 3, through the passage opening of its shaft, and the discharge through the liquid guide channel 39, the connecting pipes 38 and inlet pipes 36, the microfiltration jar 33 and the fine mesh element 27 of the microfilter 29 and return part of the liquid to the tank 3 in the bottom of the tank 3, the micro-waste then being retained in the microfiltration jar 33 by the fine mesh element 27 of the microfilter 29, and during the emptying rotates in the opposite direction to suck liquid through its opening inlet 19 and the fine mesh element 27 of the microfilter 29, the connection tube 38, the liquid guide channel 39 and discharge it through the discharge line 23, the non-return valve 24 towards the outside of the machine.

The liquid in the tank 3 is thus gradually freed of micro-waste and the dishes cleaned with a liquid thus filtered requires only a reduced quantity of water in the washing and rinsing sequences of the operating programs of the dishwasher 1, compared to those required in known devices, while obtaining clean cleaned dishes when removed from the machine, the dishwasher operating programs being controlled by a programmer or an electronic control device indicated at 50, which, produced according to a known technique, will not be described in detail.

In the dishwasher 1 of the example illustrated, during the washing and rinsing of the dishes, the recycling 10 and drain 11 pumps mounted on a common shaft 13 rotate in the direction of arrow 40. The recycling pump 10 sucks up a large part of the liquid which has passed through the medium filter 26 and discharges it into the sprinkler reels 6 and 7 while the drain pump. 11, because of the presence of the non-return valve 24 on the discharge line, sucks through a passage opening 42 of the shaft of its wheel 22 a part of the liquid which has passed through the filter 26 and discharges it through the microfilter 29 in tank 3 for microfiltration of the liquid. The two pumps 10 and 11 thus create in the tank 3, two independent streams of liquid for filtering the latter.

During a draining of the liquid in the tank 3, the two pumps 10 and 11 rotate in the opposite direction to the previous one, indicated by an arrow 41. The recycling pump 10 is in this case deactivated, following an entry of the air through an air intake chimney 45, while the drain pump 11 sucks the liquid and discharges it outside through its discharge pipe 23 and its non-return valve 24. ^- When the drain pump 11 sucks , the liquid sucked comes from two different circuits: on the one hand the liquid sucked results from a suction of liquid from the bottom of the tank 3 through the large filter 28 in its intake opening 19 and its suction pipe 20, on the other hand the liquid sucked results from a suction of liquid through the fine mesh element 27, the microfiltration pot 33 of the microfilter 29, the pipes 36, 38, the liquid guide channel 39, in the pipe. suction 20. The second suction liquid circuit has several advantages. This second circuit of aspirated liquid which crosses the microfiltration pot 33 makes it possible to entrain the micro-waste which are retained there and to evacuate them. Aspiration following a circuit independent of the micro-waste retained in the microfiltration pot 33 gives the dishwasher 1 the advantage of evacuating these micro-wastes without causing a re-pollution of the liquid in the tank 3. The second circuit of aspirated liquid allows unclogging of the fine mesh element 27 of the microfilter 29.

According to an important characteristic, the washing and rinsing cycles comprises, in addition to the usual emptying at the end of these cycles, one or more brief intermediate emptying. These brief intermediate empties ensure a drive of the micro-waste retained by the microfilter 29 to reject them outside and consequently unclogging or cleaning of the fine mesh element 27 of the microfilter 29, to give the latter all its effectiveness in the microfiltration of the liquid during the entire washing and rinsing cycles of the dishwasher. These brief intermediate empties may or may not be followed by compensatory water filling.

It then remains after each emptying, that possibly some waste retained by the large filter 28 in the receptacle 34 and waste retained by the medium filter 26, which can be easily removed from the tank 3 at the end of the operation of the washer dishes.

The brief intermediate drainings during the washing and rinsing cycles of the dishwasher are carried out either at regular intervals during these washing and rinsing cycles or at shorter intervals at the end of these cycles than those at the beginning of these cycles. the means of the programmer or control device 50 (FIG. 1) which also executes in its main function, the usual selected operating programs.

In an alternative embodiment, the brief intermediate empties during the washing and rinsing cycles of the dishwasher are triggered each time one or more predetermined gradual thresholds of liquid temperatures in the tank 3 of the dishwasher are exceeded. In this variant embodiment, a temperature sensor of a known type 51 (FIG. 2), placed in the liquid bath at the bottom of the tank 3 of the dishwasher, is associated with the programmer or control device 50 for implementing these brief intermediate drainings.

In another alternative embodiment, the brief intermediate emptying operations during the washing and rinsing cycles of the dishwasher are carried out each time the pressure of the stream of liquid inside the microfiltration pot 23 of the microfilter 29 exceeds a threshold of predetermined pressure. As the retained micro-waste covers the surface of the fine-mesh element 27 and hinders the passage of the stream of liquid subjected to microfiltration, the pressure of this stream of liquid increases in the microfiltration pot 33. The pressure of the current of liquid inside the microfiltration pot 23 thus reflects the degree of clogging of the fine mesh element. For the microfiltration of the liquid to be effective during these washing and rinsing cycles, it is necessary that the clogging of the fine mesh element 27 by the micro-waste does not exceed a predetermined degree. In this variant embodiment, a pressure sensor of a known type 52 (FIG. 3) having an adjustable threshold of liquid pressure and disposed in the microfiltration pot 33 of the microfilter 29, is associated with the programmer or control device 50 for trigger a brief intermediate drain each time this threshold is exceeded by the liquid pressure in this microfiltration pot 33.

In an alternative embodiment not shown, the lower spray reel 6 of the dishwasher is provided, in the surface of its lower half facing the medium filters 26, coarse, 28 and microfilter 29 of the filtering device 9, with a with several nozzles creating one or more unclogging water jets directed more or less perpendicularly on the surface of the fine mesh element 27 of the microfilter 29. This or these water jets allow, by their periodic passages on the microfilter 29 , periodically take off the micro-waste which, being in the microfiltration pot 33, tends to cling to the fine mesh element 27. The unclogging effects of the microfilter 29 by these water jets sent from the watering reel lower 6, thus adding to the effects of unclogging by brief intermediate emptying, described in previous paragraphs, to make the microfiltration of liquid in the dishwasher even more effective 1.

A dishwasher produced according to the invention is not only economical but also provides clean dishes with a relatively reduced amount of water used during washing and rinsing compared to that used in known dishwashers.

In the dishwasher 1, since it occupies only a fraction of the surface of the bottom of the tank 3, the microfilter 29 does not hinder the recycling of the liquid carried out by the recycling pump 10 and therefore the cleaning of the dishes, while allowing a progressive microfiltration of this liquid. The meshes of the medium filter 26 which occupies the majority of the surface of the bottom of the tank 3 of the dishwasher, have been determined so that the flow of recycling liquid is sufficient for effective washing and rinsing of the dishes, despite the presence of waste retained by these filters.

As a result, in each of the operating programs of the dishwasher 1, the quantity of liquid consequently the quantity of liquid provided for each phase of the operating programs is thus advantageously reduced compared to that required in a known dishwasher, without compromising the efficiency of the machine. In addition, a reduction in the quantity of liquid results in an advantageous lowering of the consumption of electrical energy in the implementation of each of the operating programs of the dishwasher 1. The dishwasher 1 produced according to the invention is of this economic fact in its operation.

In an alternative embodiment not shown, the microfilter 29 can be mounted in the tank 3 below the medium filter 26, and placed in communication with the drain pump 11 for an operation similar to that of the microfilter of the example illustrated. and described in the previous paragraphs. In this case the liquid discharged through the microfilter 29 by the drain pump 11, following the washing and rinsing of the dishes, is discharged into the tank 3 in the space below the medium filter 26 instead of being returned to the tank 3 in the space above this medium filter 26.

Claims (9)

1. Dishwasher provided, during the washing and rinsing cycles, with liquid microfiltration by a current of liquid passing through a fine mesh element (27) of a microfilter (29), and at the end of these washing and rinsing cycles of a liquid drain creating a reverse current of the liquid through this microfilter (29) and discharging towards the outside this liquid and the micro-waste retained by this microfilter, characterized in that it comprises in its operation during the washing and rinsing cycles, in addition to the usual oil changes at the end of these cycles, one or more brief intermediate oil changes. 2. Dishwasher according to claim 1, characterized in that in its operation during the washing and rinsing cycles the brief intermediate drainings are carried out at regular intervals. 3. Dishwasher according to claim 1, characterized in that in its operation during the washing and rinsing cycles the brief intermediate drainings are carried out at shorter intervals at the end of these cycles than those at the start of these. 4. Dishwasher according to claim 1, characterized in that in its operation during the washing and rinsing cycles, the brief intermediate empties are triggered each time one or more predetermined gradual thresholds of liquid temperatures in the tank are exceeded. dishwasher. 5. Dishwasher according to claim 1, characterized in that in its operation during the washing and rinsing cycles the brief intermediate drainings are carried out each time the pressure of the liquid stream inside the microfilter (29) exceeds a predetermined pressure threshold. 6. Dishwasher according to one of claims 2 and 3, characterized in that it comprises a programmer or device for electronic control (50) which executes both the usual chosen operating programs of a dishwasher, and the brief intermediate changes during the wash and rinse cycles. 7. Dishwasher according to claim 4, characterized in that it comprises a temperature sensor (51) which, associated with a programmer or electronic control device (50) of the machine, and arranged in the liquid bath the tank (3) has one or more adjustable temperature thresholds and triggers a brief intermediate drain during the washing and rinsing cycles, each time each of these thresholds is exceeded, by the temperature of the liquid in the machine, entered by this sensor. 8. Dishwasher according to claim 4, characterized in that it comprises a liquid pressure sensor (52) which, associated with a programmer or electronic control device (50) of the machine and arranged in the microfiltration pot (33) of the microfilter (29), has an adjustable pressure threshold and triggers a brief intermediate emptying during the washing and rinsing cycles, each time this threshold is exceeded by the liquid pressure in this microfiltration pot (33). 9. Dishwasher according to one of claims 1 to 8, characterized in that it comprises in its operation of brief intermediate emptying followed by compensatory filling with water from the machine.

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