Abstract:
A liquid pump has a rotor in a pump housing which has a pump chamber, a pump base, a pump-chamber wall and a cover. The rotor rotates just above the pump base, the pump-chamber wall being provided around the outside of and slightly spaced apart from the rotor and having a heating means thereon. An inlet to the rotor is provided centrally in the axial direction towards the rotor and an outlet from the pump housing is provided externally at the periphery of the pump-chamber wall. Blade-like guiding elements which are integrally injection-moulded thereon are arranged on the pump base, radially outside the impeller.

Description:
[0001]    This application is a National Stage application, filed under 35 U.S.C. §371, of International Application PCT/EP2011/069810, filed Nov. 10, 2011, which claims priority to German Application No. 10 2010 043 727.1, filed Nov. 10, 2010, both of which are hereby incorporated by reference in their entirety. 
     
    
     TECHNOLOGICAL FIELD 
       [0002]    The invention relates to a pump, in particular to a liquid pump, which comprises a rotor or an impeller in a pump housing. 
       BACKGROUND 
       [0003]    From U.S. Pat. No. 6,736,598 B2 a liquid pump is known, which comprises a pump housing having a rotor or impeller arranged therein. A heating element is provided at the exterior wall of the pump chamber or of the pump housing. 
         [0004]    WO 2010/034488 A1 describes another liquid pump including a rotor or impeller in a pump housing. In this case, a heating element can be provided in a pump chamber of the pump housing, or as an alternative also externally on a pump chamber wall. The rotor comprises a central inlet directed towards said rotor in axial direction. An outlet from the pump housing is provided on the outer periphery of the pump chamber wall in radial direction. 
       BRIEF SUMMARY 
       [0005]    The object underlying the present invention is to provide an aforementioned pump by means of which problems of the prior art can be prevented and in particular by means of which a very efficiently-working pump can be provided that can be produced by simple ways and means. 
         [0006]    The object is achieved by a pump. Advantageous as well as preferred embodiments of the invention are subject-matter of the dependent claims and will be explained in more detail in the following. The wording of the claims is incorporated into the content of the description by explicit reference. 
         [0007]    It is provided that the pump housing comprises a pump chamber including a pump bottom, a pump chamber wall as well as a cover thereon. The rotor rotates above the pump bottom, advantageously at a small distance thereto. The pump chamber wall extends around the rotor, advantageously at a certain distance thereto, and comprises a heating means. An inlet towards the rotor or the pump chamber is provided centrally and in axial direction towards the rotor. An outlet from the pump housing or the pump chamber is provided on the outer periphery of the pump housing or of the pump chamber wall. 
         [0008]    According to the invention, guide elements are provided at the pump bottom which are arranged radially outside of the rotor, i.e. surrounding the latter. The advantage of said guide elements is that they guide the liquid current inside the pump in an especially well manner, in particular towards a pump chamber wall heated by means of the heating means. Thus, an optimized input of heat from the heating means into the pumped liquid is effected. The guide elements can cause that the number of rotations or circulations of the water along the pump chamber wall and thus along the heating means is increased or that an additional rotation of the water inside the pump along the heated pump chamber wall takes place, respectively. Due to the fact that the pump chamber wall is flown against flatly and, so to say, with minimized transition, a current rupture can be prevented, wherein the angle is supposed to be very flat or acute by means of the configuration of the guide elements. In this case, the liquid current advantageously flows along the pump chamber wall towards the outlet. 
         [0009]    Advantageously, the guide elements are not only provided at the pump bottom, but even arranged thereon or fixed thereto. Advantageously, the pump bottom can be configured integrally and in one piece with the guide elements thereon. In this case, production in one piece from plastics lends itself. This way, indeed the production of the pump bottom is slightly more elaborate, however, an additional assembly step for the guide elements can be dispensed with. Furthermore, the position of the guide elements in relation to the rotor, which can also be supported at the pump bottom or at least be supported with reference thereto, can be improved or configured more exactly. This can increase the efficiency of the pump. Another advantage of such guide elements, besides the increased efficiency or heating effect of the pump, is that the noise generation inside the pump is reduced because of a current guided in a better manner. 
         [0010]    In a further embodiment of the invention, the guide elements can be configured in a curved manner in radial direction. In this case, they can be bent or curved in the rotation direction of the rotor. Thus, they can advantageously have the form of so-called guide blades for a particularly favorable guiding of the liquid current. 
         [0011]    In an embodiment of the invention, it is of advantage if the guide elements reach almost as far as up to the pump chamber wall. Thus, the internal face of the pump chamber wall is flown against as precisely as possible. A distance of a few millimeters up to one or two centimeters can be sufficient. Towards the inside, the guide elements can approach the rotor or impeller relatively closely. Here, a distance can be a few millimeters. 
         [0012]    Advantageously, the rotor can be slightly more embedded into the pump bottom than lower or radially inner regions of the guide elements. This can in particular apply to a rotor bottom part so that rotor blades extending on the rotor bottom part are quasi continuously continued in their course by the guide elements. This continuation of the course applies to both the curvature along the rotation direction of the rotor and any other curvature. Said curvature can also be present such that both the rotor blades and the guide elements extend away from the pump bottom in a bent or curved course as from a certain point. Up to said point, the rotor blades can be curved as from a rotor central region downwards towards the pump bottom. 
         [0013]    In an embodiment of the invention, it can be provided that the pump chamber including the cover on top or its sealing extends upwards almost up to the rotor, namely into the direction towards the pump bottom. In this case, the cover of the pump is the region which limits the pump chamber around the inlet upwards or which is located inside the pump chamber wall, respectively. In this case, it can even be provided that the cover partially is below the topmost region of the rotor, preferably in the rotor central region thereof, so that the cover slightly follows the course of the rotor with its shape. Towards the outside, the cover bends away from the rotor and rises far above said rotor or the pump bottom in the direction towards the pump chamber wall. Said bending of the cover away from the rotor can advantageously be effected approximately at the external diameter of the rotor. Thus, above the guide elements, the cover ascends strongly again and releases a certain space above said guide elements, which space can be used by the liquid current to stream along the pump chamber wall. 
         [0014]    Approximately three to twenty of such guide elements can be provided at the pump. Advantageously, there are six to eight guide elements. It is possible to provide as many rotor blades as guide elements. However, this is not mandatory, in particular also more guide elements than rotor blades can be provided. 
         [0015]    In a further embodiment of the invention, the outlet of the pump chamber can be arranged on the radial outer periphery of the pump chamber. Said outlet can be formed by means of a course of the pump chamber that ascends more and more upwards away from the pump bottom. Here, in the upper region, the pump chamber has a ring-shape, since radially inwards, the cover of the pump chamber extends obliquely upwards. The outlet can lead out of the pump chamber in rotation direction or circumferential direction, quasi as tangential output of the liquid. 
         [0016]    Advantageously, the pump chamber wall is configured integrally or in one piece with the heat element thereon. If, here, a shock or the like can be prevented into the circumferential direction, the liquid can stream along a smooth surface and there will not be so many swirls. Indeed, compared to a swirled liquid current, the heat transfer slightly deteriorates. However, this can easily be counterbalanced in that especially also the guide elements can cause an additional circulation of the liquid current along the heated pump chamber wall so that a corresponding heat transfer or heating of the liquid can take place. 
         [0017]    These features and further features arise, besides from the claims, also from the description and the drawings, wherein the individual features can be realized in each case on their own or in the form of sub-combination of multiple features in an embodiment of the invention and on other fields and can represent advantageous embodiments as well as embodiments capable of being protected, for which protection is claimed in this case. The division of the application into individual sections and cross headings does not limit the general validity of the statements made therein. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0018]    One exemplary embodiment of the invention is schematically shown in the drawings and will be explained in more detail in the following. The drawings show in: 
           [0019]      FIG. 1  a section through a pump according to the invention, 
           [0020]      FIG. 2  an oblique plane view of a partially disassembled pump or a view into the housing thereof, and 
           [0021]      FIG. 3  a plane view of the illustration according to  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    In  FIG. 1 , a pump  11  is shown, which can be used particularly well for a dishwasher or a washing machine. The pump  11  comprises a pump housing  12 , the course of which can be seen from the checked and hatched illustration. In this case, it can be seen that a motor  14  for driving the pump  11  is arranged in or on a housing bottom  13 . 
         [0023]    A cover  15  of the pump housing  12  is configured with a depression  15 ′ extending from outside to downwards inside, which depression circumferentially has an approximately constant distance to the housing bottom  13 . Inside the depression  15 ′, there is an inlet tube  16  which is formed integrally to the cover  15 . Said tube is arranged exactly centrally above the dot-dashed central longitudinal axis of the pump  11 , along which also a rotational axis of the motor  14  is running. 
         [0024]    The housing bottom  13  and the cover  15  are interconnected by means of a side wall  17  or said three parts essentially form the pump housing  12 . As can be seen, without further explanation, the side wall  17  rests against the housing bottom  13  and the cover  15  in a sealed manner by means of multiple sealings  18 . 
         [0025]    In this case, the side wall  17  is configured as heating element. For this purpose, it advantageously consists of a support material such as metal, in particular stainless steel, where appropriate alternatively of temperature-resistant plastic. Onto said support material, a heating element is applied in a planar manner which can be effected, if applicable, as usual and with an insulation layer underneath. Advantageously, this is effected at the exterior side facilitating an electrical connection and reducing insulation problems. The heating elements can advantageously be applied using thick film technology, which is generally known to the person skilled in the art and which will therefore not be explained in more detail here. 
         [0026]    Just marginally above the housing bottom  13 , an impeller  20  is supported as rotor on a shaft of the motor  14 , the shape of which impeller is also known per se. Said impeller comprises impeller blades  21  which cannot be seen very well in the sectional view of  FIG. 1 , which is why reference is made to the oblique view of  FIG. 2 . 
         [0027]    Regarding the configuration of the cover, it is to be noted that the upper edge thereof gradually extends upwards in the circumferential direction as far as up to the elevation  15 ″. Said elevation then merges into an outlet tube  19  as generally known per se from such impeller pumps. 
         [0028]    The three parts of the pump housing  12  are held together via two external connectors  22 . According to the illustrations in  FIGS. 2 and 3 , four such connectors  22  are provided. 
         [0029]    On the upper side of the housing bottom  13 , which is composed of plastic, multiple guide elements  24  are provided. As can be seen from the right guide element  24  in sectional view of  FIG. 1 , the seven guide elements  24  are integrally formed to the housing bottom  13 , in particular injection-molded. This is not a problem in case of a production of plastics. The elongate and curved or bent shape of the guide elements  24  can also well be seen from the  FIGS. 2 and 3 . Towards the inside, they extend almost up to the impeller  20 , and towards the outside they have a slight distance to the side wall  17 , for example several millimeters. In this case, it is obvious that seven guide elements  24  are provided and five impeller blades  21 . The latter are shown in the plane view with dashed lines. Furthermore,  FIG. 3  shows that the curvature of the impeller blades  21  is inverse to the curvature of the guide elements  24 . However, this is also generally known to the person skilled in the art. 
         [0030]    Furthermore, as can be seen from  FIGS. 1 and 2 , the guide elements  24  are configured such that in the region towards the impeller  20 , they have approximately the height of said blades or slightly surpass the height of the impeller blades  21 . The height of the guide blades can vary in the course of the blades, it can, for example, decrease towards the outside and even become zero, if appropriate. 
         [0031]    It can also be seen from  FIG. 1  that the housing bottom  13  in the region the guide elements  24  rest on it or are integrally shaped thereto, extends upwards towards the outside, that is extending upwards outside of the impeller  20 . As a result, also a transport of the water supplied by the pump  11  upwards is facilitated or effected. The water supplied effects multiple circulations inside the pump housing  12  before it is transported that high that it leaves the pump  11  again through the elevation  15 ′ and the outlet tube  19 . A kind of deflection plate helps to transport the water upwards. However, said plate does not contribute to the number of circulations of the water. It can also be seen from  FIG. 1 , that the interior of the pump housing actually essentially forms a circular ring-type volume. In particular, it is to be observed in case of said shape of the pump housing  12  or the internal space respectively, that the ratio between volume and area of the side wall  17  is relatively small, i.e. that the side wall  17  is relatively large compared to the volume. This can quasi be seen from the distance between the side wall  17  and the cover  15  above the depression  15 ′ of the cover. In case the entire pump housing  12  is filled with the water to be transported, a water volume streaming along the side wall  17  can very well be heated by means of the heating element function of said wall. The fact that the water transported indeed is subject to several circulations inside the pump housing  12 , as explained above, even improves said effect. 
         [0032]    For transporting or directing the water, the aforementioned guide elements  24  are of major importance. Said elements additionally put the water into circulation and direct it towards the side wall  17  in the aforementioned flat angle. Thus, the result is a very good and rapid nestled current. This can hardly be achieved that well only by means of the impeller  20  alone or the impeller blades  21  thereof. 
         [0033]    The additional advantage according to the invention of the preferred integral molding of the guide elements  24  to the housing bottom  13  is the simpler producibility, since in this case the housing bottom  13  can be produced as injection molded part entirely. As a result, the guide elements  24  are also fixed to the housing bottom  13  in a significantly more stable manner. Furthermore, they can be provided with smooth transitions and without gaps or the like at the housing bottom  13 , so that here the liquid current can be guided as good as possible and to the desired extent. As a result of the impeller  20  being embedded slightly more into the housing bottom  12  according to  FIG. 1 , it can be achieved that radially outside thereof, the housing bottom  13  is guided outwards exactly in the lower regions of the impeller blades  21 . This way, the liquid current can likewise be guided most advantageously. 
         [0034]    The side wall  17  can, as can be seen from  FIGS. 2 and 3 , be configured as closed circular ring, that is to say without a joint or the like. Said wall can either be composed of a seamless tube or been cut off from a longer tube of such type. As an alternative, it can be bent from a metal sheet strip, the end edges of which are connected as butt joint, however smooth or in a manner, that the abutting is closed and smoothened afterwards. The subsequent application of the heating device thereon is not a problem, since mainly also thick film heating elements can be applied on curved faces by means of corresponding printing methods.