GB2255592A

GB2255592A - Dishwasher emptying pump.

Info

Publication number: GB2255592A
Application number: GB9206515A
Authority: GB
Inventors: Ugo Favret
Original assignee: Zanussi Elettrodomestici SpA
Current assignee: Electrolux Zanussi Elettrodomestici SpA
Priority date: 1991-03-27
Filing date: 1992-03-25
Publication date: 1992-11-11
Anticipated expiration: 2012-03-25
Also published as: DE9203797U1; ES1020701Y; IT225639Y1; ITPN910008U1; ES1020701U; FR2674579B3; FR2674579A1; GB2255592B; GB9206515D0; ITPN910008V0

Abstract

The centrifugal pump 8 comprises a pressure chamber 14 with a central suction opening 13 shaped with at least one slit 16 with a gauged section extending radially as far as the inside top of the pressure chamber. At least one side edge of the gauged slit 16 is shaped throughout its length with a deflecting projection 18 protruding towards the side of the pressure chamber 14. <IMAGE>

Description

CENTRIFUGAL EMPTYING PUMP, PARTICULARLY FOR WASHING MACHINES The present invention relates to a centrifugal pump, particularly for a washing machine, able, for example, to empty the working liquid out of the tub of a washing machine through an emptying hose.

As is well known the emptying hose of a washing machine is normally flexible, and it may easily happen that it could be mounted in curved fashion with one or more elbows in which, at the end of an emptying phase, water remains, preventing the delivery of the emptying pump from communicating with the outside of the machine.

It is known, furthermore, that at the end of an emptying phase the water in the wash tub of the machine lies at a residual level which, generally, is lower than the top of the pressure chamber of the emptying pump.

Under such conditions, accordingly, the water collecting on the bottom of the wash tube of the machine traps inside the pump a volume of air which cannot be blown outwards through the emptying hose and prevents, therefore, a correct priming of the actual pump in a subsequent emptying phase.

To reduce such a drawback solutions have been proposed which provide for an additional bleeder tube suitably mounted and connected to the emptying pump for the latter to be primed more correctly. Such solutions, however, complicate to an undesirable extent the structure and the assembly of the machine.

The present invention has for its object to provide a simple centrifugal emptying pump of compact structure and of operation substantially such as not to be influenced by possible anomalous installation conditions.

According to the invention such an aim is achieved in a centrifugal emptying pump, particularly for washing machines, incorporating the characteristics of the attached claims.

The characteristics and advantages of the invention will be made clear by the following description, given only as a non-limitative example, with reference to the attached drawings, wherein: Fig. 1 shows in diagrammatic form the #principal working components of a washing machine using the pump of the invention; Fig. 2 shows diagrammatically a perspective of the centrifugal pump of the invention; Fig. 3 shows in diagrammatic form a top view of the pump of Fig. 2, in section along a plane A.

Referring to Fig. 1, the washing machine is, for example, a dishwasher, comprising mainly a wash tub 3 the bottom of which is connected with a sump 4 for collecting the washing water. A feed pump 5 is designed to suck water out of the sump 4 to feed at least one rotary sprayer 6 which is mounted in known manner in the tub 3 above a filter 7. Also in known manner the filter 7 is shaped as in Fig. 1 and substantially divides the inside of the tub 3, 4 into a hydraulic washing circuit and a hydraulic emptying circuit. The washing circuit comprises the rotary sprayer 6 and the feed pump 5, the suction of which communicates within the tub 3 through the filter 7.The emptying circuit comprises a centrifugal emptying pump 8 the suction 9 of which communicates directly with the tub 3 and the delivery 10 of which is connected with an emptying hose 11, preferably flexible.

For space reasons the emptying pump 8 has preferably a horizontal axis.

More precisely, referring also to Figs. 2 and 3, the suction arrangements of the pump comprise an inlet duct 12 which extends substantially horizontally from a suction opening 13 provided centrally in the pressure chamber 14 of the emptying pump. Preferably, such a suction opening 13 is substantially placed at the bottom of the wash tub 3, 4, as a consequence of which the upper part of the pressure chamber 14 is situated above the residual level L which the water normally reaches in the tub 3, 4, in known manner, at the end of each emptying phase. Let it further be assumed that the emptying hose 11, extending towards the top of the pump 8, is positioned in such a manner as to form at least one elbow 15 Ushaped. In known manner, consequently, at the end of each emptying phase, in the elbow 15, a quantity of water collects which occludes the emptying tube 11.

According to an embodiment of the invention, the central suction opening 13 of the emptying pump 8 is shaped with at least one slit 16 of gauged cross-section which extends substantially radially up to the inside top of the pressure chamber 14. In addition, similarly to the suction opening 13, the gauged slit 16 extends substantially throughout the axial length of the inlet duct 12 which is preferably designed to be integral with the chamber 14 of the emptying pump. Preferably, however, the free end of the inlet duct 12 is made in the form of a hollow cylinder, with an annular edge 17 protruding axially from the suction opening 13 and from the slit 16 which are diametrically encompassed within the said edge 17. The annular edge 17 lends itself to being con veniently connected with a possible auxiliary duct (not shown) should it be desirable to extend the inlet duct 12 horizontally.

In operation, when water is admitted to the wash tub 3, 4, the water rises from the residual level L and the air trapped inside the emptying pump 8 cannot flow out along the emptying hose 11 if the latter is in the state described above and shown in Fig. 1. The trapped air, however, can flow out of the pressure chamber 14 towards the end 17 of the inlet duct 12 through the gauged slit 16. The bleeding of the air can take place until the water reaches a level equal to that of the inside top of the pressure chamber 14, as a consequence of which the latter is completely filled by the water admitted to the washing machine. Consequently, when the pump 8 is subsequently operated to perform an emptying phase, it becomes primed in optimum manner, sucking water through the opening 13.

Naturally, during the operation of the emptying pump 8, part of the pressurized water tends to flow back from the chamber 14, along the gauged slit 16, towards the end 17 of the inlet duct 12, correspondingly reducing the hydraulic performance.

According to another embodiment of the invention, such a drawback is substantially obviated due to the fact that at least one side edge of the gauged slit 16 is shaped throughout its length with a deflecting projection 18 protruding towards the side of the pressure chamber (Fig. 3). Preferably, should the impeller 19 of the centrifugal pump be actuatable in a predetermined direction of rotation (indicated by the arrow in Fig.

3), the deflecting projection 18 will be provided on the edge of the slit 16 arranged further upstream relative to the actual direction of rotation. In any event, it has been found, experimentally also, that the deflecting projection 18 deflects the flow of pressurized water circulating in the pressure chamber, advantageously preventing its flowing out through the gauged slit 16.

In chamber 14, indeed, downstream of the deflecting projection 18 there occurs a depression such as to permit a suction of water also through the gauged slit 16.

Obviously, the centrifugal emptying pump described may undergo numerous modifications falling within the scope of the invention. For example, the gauged slit 16 may have a curvilinear section, while the dimensions and the inclination of the deflecting projection 18 may easily be calculated by a specialist in this field, on the basis of the overall dimensioning of the centrifugal pump 8.

Claims

CLAIMS:

1. Centrifugal emptying pump, particularly for washing machines, comprising a pressure chamber with a central suction opening, characterized in that the said suction opening (13) is shaped with at least one slit (16) with gauged section extending substantially radially as far as the inside top of the said pressure chamber (14).

2. Centrifugal pump according to claim 1, characterized in that the said suction opening (13) and the said gauged slit (16) extend substantially throughout the axial length of an inlet duct (12) substantially horizontal designed integrally with the said pressure chamber (14).

3. Centrifugal pump according to claim 1, characterized in that at least one lateral side of the said gauged slit (16) is shaped throughout its length with a deflecting projection (18) protruding towards the inside of the said pressure chamber (14).

4. Centrifugal pump according to claim 1, characterized in that the free end of the said inlet duct (12) is designed as a hollow cylinder, with an annular edge (17) projecting axially from the suction opening (13) and from the gauged slit (16) which are diametrically inscribed in the said edge (17).