Enhanced discharge pump for household appliances and washing machine or dishwasher comprising said discharge pump

Abstract

A discharge pump for household appliances comprising: an electric motor; an impeller; a volute chamber within which said impeller rotates; said volute chamber being delimited by: a top on which a fluid suction is present; a side wall on which a fluid supply opens; and a bottom provided with a transmission opening for the kinematic connection al electric motor; said impeller comprising a plate, a plurality of main blades arranged on a side of said plate facing the top, and at least one projection protruding from said plate toward said bottom; said bottom having a counter-projection protruding toward the plate of the impeller, arranged in a radially inner position with respect to the projection; said at least one projection and said at least one counter-projection forming a labyrinth fluid path between the volute chamber and the transmission opening.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to European Patent Application No. 25425004.6, filed Feb. 7, 2025, the entirety of which is incorporated herein by reference.FIELD OF APPLICATION

[0002] In its more general aspect, the present invention relates to a discharge pump for fluids. Said pump finds its preferential application as a discharge pump in household appliances.

[0003] Therefore, the invention finds a useful application in the field of household appliances, in particular as a component for large household appliances such as, by way of example, washing machines or dishwasher.

[0004] The invention also relates to a washing machine or dishwasher comprising the above discharge pump.Prior Art

[0005] As above mentioned, discharge pumps are traditionally used in the field of household appliances, in particular for draining dirty water at the end of a washing cycle.

[0006] In the pumps of the above type, permanent magnet synchronous electric motors are mainly used. Said motors comprise a stator, having a lamination pack electromagnet and related windings, and a rotor provided with one or more permanent magnets arranged between at least two polar expansions defined by the stator; the rotor is axially passed through by a motor shaft, integral thereto, rotatably connected to the pump casing.

[0007] The electric motor is coupled to the impeller, usually with interposition of a sliding rubber coupling system in order to overcome the problem of the starting torque, said impeller being arranged to send the fluid to be drained from a suction toward a delivery.

[0008] One of the known drawbacks of the discharge pumps according to the prior art is the possible pump malfunction due to debris entering the pump during the operation thereof. In particular, the presence of sand or contaminants with similar grain size in the incoming water is particularly critical. Indeed, the sand may be fine enough to pass through the filter upstream of the discharge pump, and risks to infiltrate into the space between the lower plate of the impeller and the bottom of the volute chamber.

[0009] The accumulation of sand and / or other small-grained particles may lead to a progressive reduction in the discharge pump flow, or to a worsening of the hydraulic efficiency which may lead to a real blockage of the pump.

[0010] Moreover, the accumulated sand, even before causing a blockage or compromising the restart of the pump, causes a substantial increase in noise during operation.

[0011] Several solutions have been proposed by prior art devices which, however, although partially advantageous, have not optimally solved the above problem.

[0012] Therefore, the technical problem of the present invention is to provide a discharge pump that solves the prior art drawbacks.

[0013] The main object is to provide a discharge pump with self-cleaning properties, namely that generates enough turbulence to keep the area underneath the plate of the impeller clear of debris.

[0014] Another object of the present invention is to avoid any risk of seizure due to the presence of debris, in particular due to restricted dimensions and / or geometries.

[0015] Still another object of the present invention is to increase the quietness of the device's rotation, even during the useful life thereof.

[0016] A further object of the invention is to provide an optimal solution also from a point of view of fluid dynamics operation of the discharge pump, thus creating a hydraulic balance that avoids impeller lifts.

[0017] Another object of the invention is to provide a structurally solid and robust solution over time, thus avoiding frequent maintenance interventions or pump replacement.

[0018] Still another object is to minimize the noise of the pump during its operation.

[0019] Finally, still an object of the invention is to provide a solution with low production costs and particularly suitable for large-scale production.SUMMARY OF THE INVENTION

[0020] The solution idea underlying the present invention is to create an impervious fluid path, optimally designed to prevent debris from infiltrating beneath the impeller, also minimizing the possibility of debris accumulation.

[0021] The above technical problem has been solved by means of a discharge pump for household appliances comprising:

[0022] an electric motor;

[0023] an impeller;

[0024] a volute chamber within which said impeller rotates; said volute chamber being delimited by: a top on which a fluid suction is present; a side wall on which a fluid supply opens; and a bottom provided with a transmission opening for the kinematic connection to the electric motor;

[0025] said impeller comprising a plate, a plurality of main blades arranged on a side of said plate facing the top, and at least one projection protruding from said plate toward said bottom;

[0026] said bottom having a counter-projection protruding toward the plate of the impeller, arranged in a radially inner position with respect to the projection;

[0027] said at least one projection and said at least one counter-projection forming a labyrinth fluid path between the volute chamber and the transmission opening.

[0028] Advantageously, the labyrinth fluid path thus devised has been experimentally proven to be particularly effective in allowing the optimal evacuation of debris and in particular of sandy residues, thanks to the turbulence that is created at the external edge of the impeller.

[0029] The labyrinth path formed between projection and counter-projection has a reduced section since it moves outwardly, thus creating an acceleration of the fluid that determines a curtain of water that prevents the entry of sandy debris. In particular, the distance between the lower surface of the plate and the counter-projection defines the minimum-section passage.

[0030] Preferably, said bottom is substantially planar between the counter-projection and the side wall of the volute chamber.

[0031] A technical prejudice of the prior art instead considers it preferable to shape the bottom with a tilted surface, so that the lower level of said bottom is substantially lower than the pump delivery.

[0032] The planar conformation has surprisingly proven to be more effective in debris evacuation when combined with a labyrinth path of the previously discussed type. Therefore, the planar bottom and the labyrinth path have proven to be synergetic in improving the performance of the pump in the presence of sand in the evacuated water.

[0033] Preferably, and still with the purpose of obtaining a better evacuation of the sandy debris, the fluid supply opens at a level equal to that of said bottom. Conversely to the prior art, therefore, the volume below the plate of the impeller is at the same level as the delivery mouth.

[0034] According to a particularly advantageous aspect of the invention, the impeller also comprises a plurality of auxiliary blades arranged on the side of said plate facing the bottom.

[0035] The auxiliary blades are useful to balance the fluid dynamics of the impeller, thus avoiding the lifting thereof during operation.

[0036] Preferably, each of said auxiliary blades is radially protruding with respect to a hub of the impeller. This positioning of the auxiliary blades avoids reducing the levels at the periphery of the plate, so as to avoid the risks of seizure.

[0037] The auxiliary blades moreover define, along with projection and counter-projection, the labyrinth path which prevents the accumulation of debris beneath the impeller.

[0038] Preferably, said auxiliary blades are also radially projecting with respect to the plate of the impeller.

[0039] Preferably, each of said auxiliary blades has a cross section increasing in the radial direction from said hub toward the end.

[0040] Said tilted conformation of the lower profile of the auxiliary blades concentrates the fluid flow toward the radial axis, thus avoiding promoting a suction action that could lead to debris accumulation under the impeller plate.

[0041] Preferably, the cross section of the auxiliary blades increases outwardly according to an angle of inclination with respect to the horizontal plane greater than 0° and lower than 15°, preferably equal to 7.5°.

[0042] Still preferably, said auxiliary blades stop in a radially inner position with respect to the counter-projection.

[0043] Preferably, the auxiliary blades develop toward the bottom, thus reaching a lower level with respect to the maximum level of the counter-projection.

[0044] Therefore, preferably the auxiliary blades are radial blades with a rectangular or, preferably, trapezoidal conformation.

[0045] Preferably, the auxiliary blades are equally spaced and in a number comprised between six and twelve; in the preferred embodiment, they are eight, spaced apart from each other by 45°.

[0046] Preferably, said projection develops toward the bottom, thus reaching a lower level with respect to the maximum level of the counter-projection.

[0047] Preferably, said projection and said counter-projection are annular, or at least they have a closed profile. Still preferably, they are concentrical.

[0048] Preferably, said projection is peripheral with respect to the plate of the impeller, namely it is formed at the lower edge of the plate itself.

[0049] Preferably, said main blades have a radial extension grater than the plate. In particular, they can connect to the plate underneath by means of a tilted connection portion.

[0050] In a particularly advantageous manner, said bottom may be defined by a flange of the pump body casing, whereas said top and said side wall are defined by a cover coupled to said casing.

[0051] The previously defined technical problem is also solved by a washing machine or dishwasher comprising at least one discharge pump of the previously discussed type.

[0052] It is noted that the main blades are preferably straight blades.

[0053] The main blades are preferably angularly equally spaced.

[0054] In the preferred embodiment, the main blades are four in number.

[0055] Advantageously, the present solution also well fits into predefined production processes, and can be implemented without excessive cost increases compared to the current solutions.

[0056] Further features and advantages of the present invention will become clearer from the following description of an embodiment thereof with reference to the appended drawings, given by way of indicative and non-limiting example.BRIEF DESCRIPTION OF THE DRAWINGS

[0057] FIG. 1 shows a frontal view of a discharge pump according to the present invention;

[0058] FIG. 2 shows a side view of the discharge pump;

[0059] FIG. 3 shows a top view of the discharge pump;

[0060] FIG. 4 shows a side view of the discharge pump sectioned along a plane passing through the rotation axis of the impeller shaft;

[0061] FIG. 5 shows a perspective view of the discharge pump;

[0062] FIG. 6 shows a perspective view of the discharge pump with the volute removed to show the inner impeller;

[0063] FIG. 7 re-proposes the perspective view of FIG. 6 with the impeller extracted from its seat;

[0064] FIG. 8 shows a sectioned side view of the sole casing of the main body and of the impeller;

[0065] FIG. 9 shows a top view of the discharge pump devoid of volute;

[0066] FIG. 10 shows a top view of the discharge pump devoid of volute and impeller;

[0067] FIG. 11 shows a perspective view of the discharge pump impeller;

[0068] FIG. 12 shows a perspective view of the discharge pump impeller according to a different perspective from that of claim 11;

[0069] FIG. 13 shows a bottom view of the discharge pump impeller;

[0070] FIG. 14 shows a top view of the discharge pump impeller;

[0071] FIG. 15 shows a side view of the discharge pump impeller;

[0072] FIG. 16 shows a detail of the impeller in the context of FIG. 4.DETAILED DESCRIPTION

[0073] With reference to the appended figures, and in particular to FIG. 1, reference number 1 identifies a discharge pump for a large household appliance, in particular for a washing machine or a dishwasher.

[0074] It is noted that the orientation of the pump illustrated in FIG. 1 is merely illustrative and is in no way intended to represent a preferential assembly orientation of the pump. Terms describing the relative arrangement of pump elements, such as upper or lower or similar terms, must refer to this orientation.

[0075] The pump 1 comprises an electric motor 2, which, in the example illustrated, is of the synchronous type with an permanent magnet internal rotor 20 and an external stator 21. The external stator comprises, in a per se known way, a pack of U-shaped laminations 22, on whose arms windings 23 are arranged. The windings are housed in a box-like body attached to a main pump body.

[0076] Said main pump body is defined by a substantially cylindrical casing 10 for a permanent magnet rotor 20 contained therein. The casing 10, as highlighted in FIG. 8, comprises a flange 11, which, as in the example illustrated, may be made as a unique body with the casing 10, adapted to allow the connection with a cover 42 that defines the volute.

[0077] Therefore, between the flange 11 and the cover 42 a volute chamber 4 is defined, on which a fluid suction 40 and a fluid supply 41 open. The fluid suction 40 is obtained below in the cover 42, whereas the delivery is obtained laterally in the cover 42 itself.

[0078] Therefore, the volute chamber 4 has a bottom 46, defined by the flange 11, a drop-shaped side wall 44 on which the fluid supply 41 opens and a top 43 on which the fluid suction 40 opens. At the center of the bottom 46 a transmission opening 47 opens, through which the end of the motor shaft 24 extends.

[0079] As illustrated in FIG. 4, the rotor 20, enclosed in the casing 10, is passed through a motor shaft 24, which is supported and centred by opposite bushings, according to a per se known configuration which ensures the seal closure of the volume in which the rotor 20 is housed. The motor shaft 24 is rotatable about a rotation axis x of the electric motor 2.

[0080] The motor shaft 24 protrudes with an end from the rotor housing volume and is kinematically coupled to an impeller 3.

[0081] Preferably, the kinematic coupling is mediated by a coupling system which allows a free stroke of the rotor 20 upon starting before dragging the impeller along 3, to allow reaching the synchronization speed. The coupling system may be made according to several modes known to the skilled person, for instance via eccentric teeth integral to the rotor 20 and to the impeller 3, with possible interposition of an intermediate body which is free to slide.

[0082] In any case, a direct coupling between the motor shaft 24 and the impeller 3 cannot be ruled out.

[0083] The impeller 3 comprises a hub 31 divided into two upper and lower portions by a plate 39.

[0084] The upper portion of the hub31 is structured as two overlapping domes. A plurality of main blades 30 develop in projection from the lower dome.

[0085] Such main blades 31, which in the embodiment herein described are four straight blades, define a fluid dynamic action on the washing fluid of the washing machine, radially expelling said flow through the fluid supply 41.

[0086] According to a preferred embodiment, the main blades 30 have a perimetral edge that is substantially rectangular and extend radially outside the plate 39, being connected to the lower edge thereof through a tilted portion 34.

[0087] Advantageously, the impeller 3, according to the present invention, comprises auxiliary blades 33 protruding from the lower portion of the hub 31, namely that develop beneath the plate 39.

[0088] The auxiliary blades 33 have a trapezoidal configuration, their lower profile being tilted so as to space apart from the bottom 46 when it gets closer to the hub 31. The inclination of the profile is preferably slightly less than 10°, in the example illustrated 7.5°.

[0089] The auxiliary blades 33 do not extend up to the peripheral end of the plate 39, ending at a distance therefrom.

[0090] At the perimeter of the plate 39, it has a projection 32 beneath, namely an annular rim, oriented toward the bottom 46 of the volute chamber 4.

[0091] The impeller 3 also has an inner cavity 37 engaged by transmission means connected to the shaft 24 and closed by a sealing washer adapted, possibly, to contain a viscous fluid in the inner cavity 37 to dampen and / or absorb any knocks and noises generated by the transmission means.

[0092] At the impeller, the bottom 46 of the volute chamber 4, defined by the flange 11, has a counter-projection 48, which in this case takes up the form of an annular wall raised above the bottom 46.

[0093] As well visible in FIG. 16, said counter-projection 48 is arranged between the auxiliary blades 33 and the projection 32 of the plate 39 above. The counter-projection 48 reaches a level greater than the minimum level of the projection and of the auxiliary blades 33.

[0094] In a diametric section, the auxiliary blades 44, the counter-projection 48 and the projection 32 define, along with the plate 39, the bottom 46 and the transition opening 47, a labyrinth path that has noticeable narrowing in the passage between counter-projection 48 and plate 39 above.

[0095] In particular, it is noted that the distance between the upper end of the counter-projection 48 and the plate 39 may be comprised between 1 mm and 2 mm, whereas the distance between the bottom 46 and the lower end of the projection 32 is significantly higher, preferably greater than 2 mm.

[0096] Said labyrinth path causes a perimeter turbulence about the impeller, which creates a self-cleaning effect, i.e. a water barrier along the lower external perimeter of the plate 39.

[0097] Therefore, an advantage of the pump according to the present invention derives from the fact that the above self-cleaning effect avoid the infiltration of debris, in particular sandy debris, beneath the plate of the impeller.

[0098] Another advantage of the pump is that it is extremely silent over time.

[0099] Another advantage of the pump made according to the present invention having an impeller with blades and auxiliary blades made integrally is that of obtaining an optimal balance of the impeller, thus allowing the reduction of any wear and tear thereof.

[0100] A further notable advantage of the impeller made according to the present invention is that it is possible to produce it at low prices in large and very large series, an advantage not least for an item intended for use in mass-market products.

[0101] Obviously, a skilled person can make several changes and variants to the above described discharge pump, in order to meet contingent and specific needs, all of them by the way contained in the scope of protection of the invention as defined by the following claims.

Claims

1. A discharge pump for household appliances comprising:an electric motor;an impeller;a volute chamber within which said impeller rotates; said volute chamber being delimited by: a top on which a fluid suction is present; a side wall on which a fluid supply opens; and a bottom provided with a transmission opening for the kinematic connection to the electric motor;said impeller comprising a plate, a plurality of main blades arranged on a side of said plate facing the top, and at least one projection protruding from said plate toward said bottom;said bottom having a counter-projection protruding toward the plate of the impeller, arranged in a radially inner position with respect to the projection;said at least one projection and said at least one counter-projection forming a labyrinth fluid path between the volute chamber and the transmission opening.

2. The discharge pump for household appliances according to claim 1, wherein said bottom is substantially planar between the counter-projection and the side wall of the volute chamber.

3. The discharge pump for household appliances according to claim 2, wherein said fluid supply opens up to a level equal to that of said bottom.

4. The discharge pump for household appliances according to claim 1, wherein said impeller comprises a plurality of auxiliary blades arranged on the side of said plate facing the bottom.

5. The discharge pump for household appliances according to claim 4, wherein each of said auxiliary blades is radially protruding with respect to a hub.

6. The discharge pump for household appliances according to claim 5, wherein each of said auxiliary blades has an increasing cross section in a radial direction from said hub toward the end.

7. The discharge pump for household appliances according to claim 6, wherein the cross section of the auxiliary blades grows according to an inclination angle greater than 0° and lower than 15°.

8. The discharge pump for household appliances according to claim 4, wherein said auxiliary blades stop in a radially inner position with respect to the counter-projection.

9. The discharge pump for household appliances according to claim 4, wherein said auxiliary blades develop toward the bottom reaching a lower level with respect to the maximum level of the counter-projection.

10. The discharge pump for household appliances according to claim 1, wherein said projection develops toward the bottom reaching a lower level with respect to the maximum level of the counter-projection.

11. The discharge pump for household appliances according to claim 1, wherein said projection and said counter-projection are annular.

12. The discharge pump for household appliances according to claim 1, wherein said projection is peripheral with respect to the plate of the impeller.

13. The discharge pump for household appliances according to claim 1, wherein said main blades have a radial extension greater than the plate.

14. The discharge pump for household appliances according to claim 1, wherein the passage between plate and counter-projection has a cross section smaller than the other passages of the labyrinth fluid path.

15. A washing machine or dishwasher comprising at least one discharge pump according to claim 1.

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