WO1992000035A1

WO1992000035A1 - Dishwasher with rotating flushing arm

Info

Publication number: WO1992000035A1
Application number: PCT/SE1991/000455
Authority: WO
Inventors: Lars-Göran KARLSSON
Original assignee: Asko Cylinda Ab
Priority date: 1990-06-29
Filing date: 1991-06-25
Publication date: 1992-01-09
Also published as: SE468114B; SE9002289L; AU8208191A; SE9002289D0

Abstract

A dishwater has a rotating spray arm (6), driven by the water jets, which is rotatably journalled in a fixed lead-in pipe in the bottom (1) of the dishwater. In the bottom of the dishwater a bottom well (2) with a fine strainer (3) is arranged. A flushing pump (14) sucks water from the well and supplies the arm with this flushing water via the lead-in pipe. At the bearing of the arm in the lead-in pipe, a collecting member (9) is arranged to capture leakage water from the bearing of the arm in the lead-in pipe and to direct this water towards the fine strainer for continuous flushing thereof.

Description

Dishwasher with rotating flushing arm

TECHNICAL FIELD

The present invention relates to a dishwasher with at least one rotating spray arm, which is rotatably mounted in a fixed lead-in pipe for supply of flushing liquid to the arm and has a number of outlet openings for the flushing liquid, and the rotary motion of which is driven by the reaction force from the flushing liquid flowing out through the out¬ let openings, the dishwasher having a bottom well, provided with a strainer, as well as a flushing pump, the inlet side of which is connected to the bottom well and the outlet side of which is connected to the spray arm via the lead-in pipe.

BACKGROUND ART

Dishwashers of the kind described above are previously known, which have a bottom well which is covered with a fine strainer. At the centre of the strainer a coarse strainer is arranged with its bottom at a lower level than the sur¬ face of the fine strainer. In operation of the dishwasher, a flushing pump sucks dishwater from that part of the bottom well which is covered by the fine strainer and supplies water to a rotating spray arm via a fixed lead-in pipe. The spray arm is provided with a number of outlet holes for the water. These are arranged such that the reaction force from the outflowing water provides a driving force for the move¬ ment of the spray arm. The dishwasher outlet is connected to the bottom well below the coarse strainer. Particles removed from the dishes remain in the fine strainer or the coarse strainer and are thereby prevented from being supp¬ lied to the spray arm and cause resoiling of the dishes.

In dishwashers of the above kind it has proved that the par¬ ticles strained off by the fine strainer remain, to an unde- sired extent, on the surface of the fine strainer. The par¬ ticles are removed for the most part from the dishes during

2 the prewash-up step or steps which initiate the washing-up procedure. Particles remaining on the surface of the fine strainer then tend to soil the washing liquid used during subsequent washing-up steps, for example during the main wash-up, thus obtaining an increased resoiling of the dishes. Further, particles located on the surface of the fine strainer will to a certain extent clog the fine strai¬ ner and cause a deterioration of its permeability. If parts of the surface of the fine strainer are in this way wholly or partially clogged, there is a risk that the flushing pump will suck air, which causes a deteriorated washing-up effect and increased sound level. A clogged fine strainer also requires more or less frequent manual cleaning, which is a considerable disadvantage.

To attain the best possible result of the washing-up with the lowest possible consumption of water, it is on the whole desirable that as large a part as possible of the dirt par¬ ticles present in the dishwasher are removed from the dishes and/or from the dish container as early as possible during the washing-up procedure, for example during the first washing-up step (the prewash-up) , and brought down into the coarse strainer, from where it will be effectively removed during the pumping out of the dishwasher prior to the next washing-up step.

It is previously known to arrange holes on the underside of the spray arm for flushing the strainer. However, this solution results in a high water consumption. Further, present-day dishwashers operate with low water levels in the dish container, and the jets from the arm which hit the strainer tend to cause formation of eddies and hence cause the flushing pump to suck air.

V It is further known to allow the filling water to flush the fine strainer clean. This method has the disadvantage that dirt particles from a preceding wash-up step remain in the dishwasher and hence increase the tendency to resoiling. It is also known to arrange one or more fixed spray nozzles which are directed towards the fine strainer for flushing the surface thereof. This method has the disadvantage of high water consumption and increased manufacturing cost.

Another problem in connection with dishwashers with rotating spray arms driven by the outflowing water is the mounting of the spray arm. Since the reaction force from the water is low, it is of great importance that the rotational resis- tance is very low. A simple bearing with low rotational resistance requires a certain play between the arm and the lead-in pipe. To prevent the gap between the arm and the lead-in pipe from being clogged, the gap must not be too small. This results in a not inconsiderable part of the total water flow consisting of the leakage flow from the bearing of the spray arm. Therefore, in prior art dish¬ washers, a considerable and quite useless increase of the water consumption is obtained, which requires a more power¬ ful flushing pump, which on the one hand increases the anu- facturing cost and the power consumption and on the other hand increases the risk of the pump sucking air at low water levels. Arranging seals to reduce the water leakage between the arm and the lead-in pipe tends unavoidably to increase the manufacturing cost, to increase the rotational resis- tance and to increase the risk of shutdown because of the gradually increasing rotational resistance resulting from the unavoidable soiling of the seal caused by dirt particles in the dishwater.

SUMMARY OF THE INVENTION

The present invention aims to provide a dishwasher of the kind described in the introductory part of the description, which affords the following advantages:

a low water consumption, 4 an effective and continuous flushing of the fine strai¬ ner and hence a considerable reduction of the risk of resoiling of the dishes and of the flushing pump suck¬ ing air,

a considerable reduction or complete elimination of the need for manual cleaning of the fine strainer,

an effective flushing early during the washing-up process of other objects present in the dishwasher, such as cutlery and the like, and thus a considerable reduction of the risk of resoiling of the dishes,

a simple construction, which is thus advantageous from the points of view of manufacturing and maintenance.

The above aim is achieved by giving the dishwasher according to the present invention the characteristic features desc¬ ribed in the appended claims .

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in the following with reference to the accompanying Figures 1- . Figure 1 shows a section through the bottom well and the lead-in pipe in a dishwasher according to the invention. Figure 2 shows the lead-in pipe and the fine and coarse strainers of the dish¬ washer, seen from above. Figure 3 shows in more detail a section through the lead-in pipe and the spray arm. Figure 4 shows another embodiment of the dishwasher, which has an upper and a lower spray arm, leakage liquid from the bearing of the upper spray arm being used for flushing of cutlery and leakage liquid from the bearing of the lower spray arm being used for flushing of the fine strainer. DESCRIPTION OF THE PREFERRED EMBODIMENTS

The figures show a dishwasher according to one embodiment of the invention. The dishwasher container has a bottom 1 in which a bottom well 2 is arranged. The well has around its edge a channel 22 against which a fine strainer 3 makes sea¬ ling contact. The fine strainer has an upper surface 31, which is somewhat sloping towards the central part of the strainer, where a coarse strainer 4 is arranged. The strai- ner surface 31 is provided with a large number of fine holes 33 through which the dishwater is able to run down to the part of the well located outside the stub tube 32 of the strainer. The stub tube 32 seals against the bottom of the well, and inside the stub tube is the coarse strainer, at the bottom of which a strainer 41 for retaining larger objects is arranged. Below the stub tube 32 the well has a drainage pipe 21, which via a schematically shown conduit 10 is connected to the discharge pump 11 and the discharge pipe 12 of the dishwasher. Adjacent to and outside the stub tube 32, the well has a stub tube 23, which via a schematically shown conduit 13 is connected to a flushing pump 14, the outlet side of which via a conduit 15 is connected to a fixed lead-in pipe 5 at the bottom of the dishwasher. The flushing water is passed via the lead-in pipe to the arm 6 of the dishwasher. This arm is rotatably journalled around a vertical shaft 7. The arm has a number of outlet holes, of which the holes 61, 62 and 63 are shown. The holes - or at least some of the holes - are directed obliquely back¬ wards in the desired direction of rotation of the arm, a .. reaction force thus being obtained which drives the arm around.

During the washing-up procedure, the flushing pump 14 operates and sucks water from the main part of the bottom well located outside the stub tube 32. The flushing water from the pump flows through the lead-in pipe out into the arm and out through its outlet openings, the dishes thus being flushed and the arm driven around. Thereafter, the 6 flushing water runs down into the bottom of the dishwasher and through the fine strainer 3, where dirt particles are separated, to the bottom well, whereupon the flushing water is again sucked to the flushing pump and so on.

The lead-in pipe 5 has a flange 51 which, possibly with an intermediate sealing ring or the like, makes contact with the upper side of the bottom plate 1 of the dishwasher. The lower part of the lead-in pipe is threaded and has a nut 8, by means of which the lead-in pipe is kept in position.

Between the arm 6 and the bottom plate 1 a collecting member 9 is arranged to collect leakage water from the bearing of the arm in the lead-in pipe 5 and to direct this leakage water towards the fine strainer for continuous flushing thereof during the washing-up process. This collecting mem¬ ber will be described in greater detail with reference to Figure 2, which shows the lead-in pipe seen from above, and to Figure 3, which shows a section through the lead-in pipe 5 and the member 9 in a vertical plane through the centre line of the lead-in pipe and parallel to the connecting line between the centres of the lead-in pipe and the coarse strainer.

The collecting member 9 consists of a cup-shaped or channel- shaped member extending around the lead-in pipe 5. The bottom 91 of the member 9 adjoins the tubular main part of the lead-in pipe 5. The cup or channel has a substantially vertical, curved wall 92 which extends around the part of the channel facing away from the fine strainer. On the part of the channel facing the fine strainer there is a V-shaped wall 93. In this way, two orifices 94, 95, directed obliquely towards the fine strainer, are formed in the channel. The bottom 91 of the channel is inclined in a direction towards the fine strainer.

The arm 6 is shown in Figure 3 in a section perpendicular to the longitudinal direction of the arm. The arm is made of sheet metal and has a bushing 64 of a suitable material with low friction, for example nylon, arranged at the centre of rotation of the arm. The lead-in pipe 5 has a centre part 53, in which a shaft 54 is arranged. The center part is supported by four radial beams 52, between which the flush¬ ing water is able to flow up to the arm. A nut 65 retains the arm in position, and between the nut and the arm there is arranged a washer of, for example, ceramics to reduce the friction. The underside of the arm has a hole concentric with the lead-in pipe 5, and there is a gap, designated by arrows 67, between the edge of the hole and the lead-in pipe. The arm plate is folded up around the hole in the manner shown in Figure 3, such that the plate edge nearest the gap 67 is obliquely upwardly-directed and makes an angle with the surface of the lead-in pipe, which has proved to be a mechanically stable design which is simple from the manu¬ facturing point of view.

During the washing-up process of the dishwasher, the flush- ing pump is operating and supplies water to the arm through the lead-in pipe. A small part of this water flows out through the gap 67 between the arm and the lead-in pipe as leakage water. This water is captured by the member 9 and is directed by the member in two flows towards the parts of the surface 31 of the fine strainer which are located on both sides of the coarse strainer . Dirt particles emana¬ ting from the dishes are continuously flushed by these water flows down into the coarse strainer and are thus prevented from adhering to the fine strainer surface. The water flows from the collecting member 9 are directed approximately parallel to the fine strainer surface and therefore provide efficient flushing of the strainer surface. For the same reason, these water flows do not give rise to any mentio- nable formation of eddies in the dishwater and thus to no risk of the flushing pump sucking air.

In this way, the fine strainer surface will all the time be kept clean, which reduces the risk of resoiling and the risk 8 of the flushing pump sucking air. Dirt removed from the dishes is continuously flushed down into the coarse strai¬ ner, remains there and is efficiently removed during the pumping out prior to the next washing-up step. The risk of this dirt soiling the water supplied during the next washing-up step is thus practically completely eliminated. In the same way, the need for manual cleaning of the fine strainer is reduced or eliminated.

Since the leakage water from the bearing of the spray arm is utilized for flushing of the fine strainer, no complicated sealing is needed to reduce the leakage water flow. As will be clear from the figures, the sealing connection between the arm and the lead-in pipe may be formed in an extremely simple manner, only by forming the arm with a hole, concen¬ tric with the lead-in pipe, the diameter of which is made so much larger than that of the lead-in pipe that a gap with a suitable width is obtained between the arm and the lead-in pipe. This completely eliminates the rotational resistance from any seals and the arm and the lead-in pipe may be manu¬ factured with small demands for tolerance, which renders the manufacturing less expensive. Further, the flushing water flowing out through the gap keeps the gap free from soiling, and the increase of the rotational resistance with time caused by the soiling, occurring in prior art seals, is eliminated.

Figure 4 shows a further embodiment of a dishwasher accor¬ ding to the invention. It has a lower dish basket 101 and an upper dish basket 103. The lower basket has a cutlery basket 102 intended for placing cutlery therein. The cut¬ lery basket may be a fixed part of the basket 101 or a de¬ tachable basket arranged for location at a certain place in the basket 101.

The lead-in pipe, connected to the outlet side of the flushing pump 14, for feeding the spray arms with washing liquid has a first part 5b, which is designed in the manner shown in Figures 1-3 as a vertical stub tube, the lower part of which is connected to the flushing pump and at the upper part of which a lower flushing arm 6b is journalled. In this embodiment, the lead-in pipe also comprises a second part 5a as well as a connecting tube 105. In the same way as the first part, the second part of the lead-in pipe is designed as a vertical stub tube, in the upper part of which an upper arm 6a is journalled. The bottom of the stub tube is closed. The connecting tube 105 interconnects the two parts 5a and 5b of the lead-in pipe and supplies the upper spray arm with washing liquid.

The upper spray arm 6a journalled in the upper part 5a of the lead-in pipe is designed and journalled in, for example, the same way as the spray arm shown in Figures 1-3 and is arranged primarily for flushing of dishes located in the upper dish basket 103.

The lower spray arm 6b journalled in the lower part 5b of the lead-in pipe is arranged primarily for flushing of dishes located in the lower dish basket 101. The arm 6b is designed and journalled in, for example, the way shown in Figures 1-3.

Around the two parts 5a and 5b of the lead-in pipe, collec¬ ting members 9a and 9b are arranged for collection of leak¬ age liquid from the bearing of the arms in the lead-in pipes. The collecting members may, for example, be designed in the manner shown in Figures 1-3.

The upper collecting member 9a directs the leakage liquid from the bearing of the upper arm towards the cutlery basket 102. This provides, early during the washing-up procedure, preferably during the first prewash-up step, a very effec- tive flushing of objects located in the basket 102. Dirt removed from these objects are -flushed down towards the bottom of the dishwasher and end up in the coarse strainer 4 (see Fig. 1), from where it is removed during the pumping out prior to the immediately following washing-up step. The risk of resoiling of the dishes is thereby considerably reduced.

The lower collecting member 9b is adapted for flushing of the fine strainer in the manner described with reference to Figures 1-3.

Tests performed have shown that in a dishwasher according to the invention, an effective flushing of the fine strainer and/or cutlery basket can be obtained at an early stage during the washing-up procedure, and hence a considerable improvement of the washing-up result .

The above-described collecting member for leakage liquid from the bearing of the arm or arms may, of course, be designed for flushing of other objects, located in the dishwasher, than those described as examples above (the fine strainer and the cutlery basket) .

The above-described collecting member for leakage water is only one example of an embodiment according to the inven¬ tion. In the embodiment described above, the collecting member is designed as an integral part of the lead-in pipe, which provides for simple manufacturing and mounting.

Alternatively, however, the collecting member may be desig¬ ned as a separate member mounted at the lead-in pipe. The embodiment described above with two orifices of the collec¬ ting member facing the fine strainer and the cutlery basket, respectively, has also proved to be advantageous, but, alternatively, the member may be designed with only one orifice or with more than two orifices . In the foregoing, the invention has been described in connection with a dish¬ washer in which water is used as washing liquid, but other washing liquids may, of course, be used. In a similar manner, the suspension, bearing arrangement and sealing of the arm or arms against the lead-in pipe may be designed in other ways than that described above.

Claims

1. A dishwasher with at least one rotating spray arm (6), which is rotatably journalled in a fixed lead-in pipe (5) for supply of flushing liquid to the arm and has a number of outlet openings (61, 62, 63) for the flushing liquid and the rotary movement of which is driven by the reaction force from the flushing liquid flowing out through the outlet openings, the dishwasher having a bottom well provided with a strainer (3) as well as a flushing pump (14), the inlet side of which is connected to the bottom well and the outlet side of which is connected to the spray arm via the lead-in pipe, characterized in that the dishwasher has at least one collecting member (9) for collection of leakage liquid from the bearing of the spray arm in the lead-in pipe and for directing the leakage liquid towards an object (3, 102) , present in the dishwasher, for flushing said object.

2. A dishwasher according to claim 1, characterized in that the collecting member (9) consists of a cup-shaped member, surrounding the lead-in pipe, with a bottom (91) adjoining the lead-in pipe and with an upwardly-directed wall (92, 93) which is provided with a number of openings (94, 95) facing the object.

3. A dishwasher according to claim 2, characterized in that the bottom (91) of the _.member is inclined downwards in a direction towards the object.

4. A dishwasher according to any of the preceding claims, characterized in that the underside of the spray arm has a hole, surrounding the lead-in pipe, with a larger diameter than that of the lead-in pipe, thus creating a gap (67) between the arm and the lead-in pipe.

5. A dishwasher according to claim 4, characterized in that that part of the arm which is located nearest the gap (67) consists of a plate edge arranged at an angle to the lead-in pipe.

6. A dishwasher according to any of the preceding claims, characterized in that the collecting member (9) is arranged to direct the leakage liquid towards the strainer (3) for flushing said strainer.

7. A dishwasher according to any of claims 1-5, which comprises a cutlery basket (102) , characterized in that the collecting member is arranged to direct the leakage liquid towards the Cutlery basket for flushing objects present therein.

8. A dishwasher according to claims 6 and 7, which has an upper (6a) and a lower (6b) spray arm, each of which is rotatably journalled in a lead-in pipe (5a, 5b) , characterized in that the dishwasher has a first collecting member (9a) for collecting leakage liquid from the bearing of the upper spray arm in its lead-in pipe (5a) and for directing said leakage liquid towards the cutlery basket (102), and a second collecting member (9b) for collecting leakage liquid from the bearing of the lower spray arm in its lead-in pipe (5b) and for directing said leakage liquid towards the strainer (3) for flushing thereof.