Abstract:
A radial pump for water has a drive motor, a pump chamber and an impeller revolving in the pump chamber. The impeller has a plurality of impeller blades which are designed, at least in regions, to be elastic and have a fixed mounting arranged in a region located near the impeller axis of rotation. They can bend elastically radially outward from this fixed mounting counter to a spring force.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a National Stage application, filed under 35 U.S.C. §371, of International Application PCT/EP2012/062049, filed Jun. 22, 2012, which claims priority to German Application No. 10 2011 078 017.3, filed Jun. 22, 2011, both of which are hereby incorporated by reference in their entirety. 
     
    
     TECHNOLOGICAL FIELD 
       [0002]    The invention relates to a pump for fluids, in particular to an impeller pump. 
       BACKGROUND 
       [0003]    WO 2010/034488 A1 discloses a pump for fluids which is designed as what is known as an impeller pump or radial pump. This pump has the particular feature that it can convey both water and air, for example in a dishwashing machine. Thus, it can convey, on the one hand, water for the cleaning operation and, on the other hand, air for the drying operation. So that this can be done efficiently in each case, it is generally described that a conveyor of the pump has compressor blades which have an adjustable angle of incidence. Furthermore, the rotational speeds between the conveyance of water, on the one hand, and the conveyance of air, on the other hand, differ considerably from one another and in the first case are markedly lower. 
       BRIEF SUMMARY 
       [0004]    The object on which the invention is based is to provide an initially mentioned pump, by means of which the problems of the prior art can be solved and, in particular, an advantageous possibility can be afforded of using such a pump with an impeller or compressor universally and in each case very efficiently. 
         [0005]    This object is achieved by means of a pump. Advantageous and preferred refinements of the invention are the subject matter of the further claims and are explained in more detail below. The wording of the claims is made the content of the description by explicit reference. 
         [0006]    There is provision whereby the pump is designed as a radial pump or as an impeller pump, with a rotating compressor or impeller revolving in a pump chamber. This compressor or impeller is designated hereafter as an impeller which has a plurality of impeller blades which are designed, at least in regions, to be flexible or elastic or be movable. In this case, they have a fixed mounting arranged near the impeller axis of rotation or in a radially inner region. In particular, here, they are firmly connected to the impeller, without a rotary joint having an axis or the like, by means of a material connection or adhesive bond or by being produced in one piece. The impeller blades can be bent or are movable radially outward from this fixed mounting, specifically counter to an antagonistic force or spring force. This spring force serves for pressing the impeller blades into a basic position which is explained in more detail hereafter. 
         [0007]    This basic position is advantageously the position in which the pump conveys a medium of very low density, preferably air, and may therefore also be designated as the air position. This therefore means that the abovementioned spring force attempts to press the impeller blades into the air position. In general, bending or movement of the impeller blades can then take place along the direction of rotation, especially advantageously in the direction of rotation of the impeller caused by the spring force. This therefore means that, in the normal state or in the abovementioned basic position, the impeller blades are in the air position, which is to be ensured by the spring force and in which the impeller blades are, as it were, set out to the maximum extent. 
         [0008]    Alternatively, however, it is also possible that the basic position is the position at which the pump conveys a medium of high density, preferably liquid or water, and may therefore also be designated as the water position. This therefore means that the abovementioned spring force attempts to press the impeller blades into the water position, that is to say opposite to the direction of rotation, in which case the impeller blades are, as it were, set out to only a minimum extent or are bent in to the maximum extent. 
         [0009]    In an advantageous refinement of the invention, the spring force is generated as a result of the elastic properties of the material of the impeller blade itself, that is to say inherently by the impeller blade itself For this purpose, the impeller blade is advantageously composed of an appropriate plastic, for example of an elastomer having the desired elastic properties. Attention must in this case also be given to the shape of the impeller blade. 
         [0010]    There is preferably provision whereby the impeller blades are curved monotonically radially outward from the abovementioned fixed mounting. This applies especially preferably to their entire course, in which case the curvature may vary slightly along the course, but their direction of curvature should not vary. The curvature is advantageously strictly monotonic and/or approximately uniform. In this case, as is customary per se for such impeller pumps, a curvature runs radially outward opposite to the direction of rotation. The curvature should be present in all positions and therefore also in the basic position or air position, even if it may be markedly lower here than in another position, for example for conveying a fluid of higher density, for example water, as is explained in more detail hereafter. 
         [0011]    An angle of the impeller blades to the radial direction may amount, in the state bent inward to the maximum extent, to slightly less than 90°, preferably to between 70° and 80°. This applies, above all, to the outer region of the impeller blades on account of the abovementioned curvature. In the radially inner region of the impeller blades, this angle may be considerably smaller, for example may amount to only about half or 30° to 45°. 
         [0012]    When the impeller blades are in the state bent outward to the maximum extent, that is to say in the abovementioned air position, their angle to the radial direction may amount to slightly more than 90°, preferably to between 100° and 110°. This is precisely because, above all, in this state which corresponds to the air position, the impeller blades bend when they are set out to a greater extent and they therefore change their course over their length. 
         [0013]    Admittedly, the abovementioned fixed mounting may to a certain extent enable an impeller blade to rotate in the manner of a turn-off However, it should, in itself, be essentially a torque-resistant mounting, that is to say not a rotary joint. This may be achieved, for example, in that the impeller blade is secured in a specific region of its length, preferably near the inner end, so as to have a certain longitudinal portion there. This securing may take place, for example, in that the impeller blade is firmly connected, by adhesive bonding or by being produced in one piece, to an impeller bottom disk or impeller cover disk. Although a portion adjoining the latter radially outward is then immovable per se, by contrast to the impeller blade projecting from it already extends radially outward over its length from the longitudinal portion. Such a longitudinal portion may have a length of, for example, 0.5 cm to 2 cm or may amount to 5% to 30% of the overall length, this being considered to be an adequate fastening of the impeller blade and being sufficient for stipulating a certain shape. 
         [0014]    Alternatively, it is possible, in actual fact, to provide a kind of axis of rotation for the impeller blade in the radially inner region or on the impeller. The disadvantage of this, however, is that the abovementioned spring force which attempts to press the impeller blades into a specific position, advantageously into one of the possible end positions, has to be generated via separate means. Furthermore, it is then not so easily possible for the impeller blades to bend over their length or to straighten somewhat under corresponding operating conditions. To be precise, in the case of a torque-resistant mounting of the impeller blade, the spring force can at the same time be achieved by means of the material properties of the impeller blade, as initially mentioned, and therefore by a more uniform curvature. 
         [0015]    In an advantageously simple refinement of the invention, the impeller blades run radially outward from the mounting without further guidance, that is to say are free. This means that an impeller for such a pump can be produced in a simple way with low susceptibility to faults. 
         [0016]    Alternatively to this, a guide of the impeller blades in the direction along the impeller axis of rotation may be provided. This guide should be provided radially outside the fastening of the impeller blade to the impeller, in particular as far to the outside as possible on the impeller or one of its impeller disks. It is possible that the impeller blade is arranged or projects between the impeller bottom disk and impeller cover disk and can execute a virtually guided movement along the direction of rotation if it has a certain thickness and therefore cannot be twisted or tilted in its longitudinal direction. In this case, it may come to bear against the disks or have only a very slight clearance with respect to these, so that it cannot also be deflected in an undesirable way in the direction along the impeller axis of rotation. 
         [0017]    A special possibility for guiding an impeller blade may be achieved in that the impeller blade has an elongate continuous longitudinal slot which is provided, at least in a radially outer region, in a direction parallel to the impeller axis of rotation. In this longitudinal slot, a sliding element, in particular a pin-like sliding element, may be arranged. This may, on the one hand, be movable in a slot in the impeller bottom disk and/or the impeller cover disk, advantageously along the circumferential direction, that is to say on an especially advantageously circular path. At the same time, the pin-like sliding element may be displaceable in the longitudinal slot in the impeller blade and then, in the case of the increasing or decreasing curvature of the latter, can move both in the longitudinal slot of the impeller blade and in the slot of the impeller disks, because, of course, the impeller blade is connected fixedly in terms of rotation to the impeller in the radially inner region. 
         [0018]    The provision of such a sliding element may, on the one hand, give rise to a certain additional sluggishness, which may sometimes be desirable, when the impeller blade bends up or bends in. Furthermore, tilting or twisting of the impeller blade along its longitudinal extent can be avoided. Finally, limit stops may thus be provided for the movement of the impeller blade, in particular for it to bend up and bend in. 
         [0019]    While the above-described air position of the impeller blade corresponds to a minimally curved state and the impeller blade in this case protrudes as far as possible out of the impeller and is close to a radial direction with a relatively straight course, the impeller blade, when in a water position curved to a maximum extent, may extend laterally out of the impeller less far or even not at all. Furthermore, it may in this case be held by an additionally provided stop or may bear against this. This may, in particular, be counter to the initially mentioned spring force, since, when water or another fluid of high density is conveyed, the impeller blades are automatically curved to a greater extent opposite the direction of rotation and are pressed inward into the impeller. The abovementioned spring force may therefore, of course, also be provided and then, precisely when fluid of low density is conveyed, again presses them outward into the air position, as it is known. 
         [0020]    Alternatively, there may also be provision whereby a spring force presses the impeller blades into the abovementioned water position, but not particularly strongly. If a fluid of lower density is to be conveyed and the impeller is to assume the air position for this purpose, it rotates at considerably higher rotational speed. Considerably higher centrifugal forces thereby act upon the impeller blades, and these are set further up or bend up, even counter to the abovementioned inwardly pressing spring force, and project further out of the impeller and thus assume the air position. This may also be reinforced in that regions of larger mass or even additional weights are provided on the outer regions of the impellers. 
         [0021]    In a further refinement of the invention, an abovementioned inner spring force of the impeller blade may be afforded over a substantial part of its length, advantageously over its entire length. It is possible to manufacture the entire impeller blade from a single material, and it may also have essentially a constant cross section over its length. Easier bending or specific spring properties of an impeller blade may be set both by the choice of its production material and by the cross section, for example also by recesses being provided, in particular along the impeller blade. 
         [0022]    When the impeller blade projects out of the impeller in the air position, this may take place, for example, with about 20% to 50% of its length. In this case, a sufficient amount of room must be provided radially in the pump chamber of the pump. In the state curved to the maximum extent, in particular in the water position, an impeller blade should project out of the impeller only slightly or not at all. 
         [0023]    This and further features may be gathered not only from the claims, but also from the description and drawings, while the individual features may be implemented in each case independently or severally in the form of subcombinations in an embodiment of the invention and in other fields and may constitute advantageous and independently patentable versions for which protection is claimed here. The subdivision of the application into subheadings and individual sections does not restrict the general validity of the statements made under these. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0024]    An exemplary embodiment of the invention is illustrated diagrammatically in the drawings and is explained in more detail hereafter. In the drawings: 
           [0025]      FIG. 1  shows a diagrammatic illustration of a pump with an impeller according to the invention, 
           [0026]      FIG. 2  shows an oblique view of the impeller with impeller blades both in an air position and in a water position, 
           [0027]      FIG. 3  shows a sectional illustration through the impeller from  FIG. 2  with a more detailed illustration of the course of the impeller blades in the air position and in the water position, and 
           [0028]      FIG. 4  shows a top view of a modification of the impeller blades, similar to  FIG. 3 , with solid impeller blades without longitudinal slots. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]      FIG. 1  illustrates in a highly diagrammatic illustration a pump arrangement  11  according to the invention. This pump arrangement  11  is installed in a water-carrying domestic electrical appliance, in particular into a dishwasher or washing machine, advantageously under the washing chamber of the latter. 
         [0030]    The pump arrangement  11  has a pump  12  which has a pump casing  13  and a motor  15 , the motor axle  16  of which extends into the pump casing  13  and carries a conveyor  18  which rotates inside the pump casing  13  in a pump chamber  19 . The connection of the pump casing  13  and motor  15  is advantageously fixed, for example by means of a releasable screw connection. 
         [0031]    In the version illustrated here, the conveyor  18  is advantageously of conventional design and corresponds, for example, to a conveyor, such as is known from DE 19903951 A1, to which express reference is made in this regard. Furthermore, here too, the illustration of the dimension of the pump casing  13  and of the other components is not true to scale. 
         [0032]    The pump casing  13  or pump chamber  19  has a central and axial pump inlet  21 . Furthermore, a pump outlet  23  is provided, which is arranged laterally and radially. A heating system  28  runs inside the pump chamber  19  and has heating connections  29  which are led out of the pump casing  13 . The heating system  28  illustrated is of an essentially cylinder-like design, so as to run around near to or on the wall of the pump chamber  19 , with the exception of an appropriate interruption, not illustrated, for the pump outlet  23 . The heating system may be an initially mentioned thick-film heating system, heating elements being arranged on at least one of its sides, advantageously on the outside, if appropriate also on the other or on both sides. 
         [0033]      FIG. 2  shows an impeller  18  in an enlarged oblique illustration from above. It can be seen here that the impeller  18  has an impeller bottom disk  30  and an impeller cover disk  32 , as is known per se. The impeller bottom disk  30  is of essentially flat form and the impeller cover disk  32  is designed to rise, as can be seen in the side illustration from  FIG. 1 . An intake port  33  is located in the middle of the impeller cover disk  32 , as is known per se. The above-described motor axle  16  is fastened in the impeller bottom disk  30 . The direction of rotation of the impeller  18  in  FIG. 2  is counterclockwise. 
         [0034]    The impeller  18  has five impeller blades  35  which are illustrated in  FIG. 2 , on the one hand, as impeller blades  35  in a state bent out to the maximum extent. This state corresponds to an initially mentioned air position of the impeller blades  35 . On the other hand, however, the impeller blades are also illustrated, at least in the lower region, by reference symbol  35 ′. It becomes clear, in conjunction with  FIG. 3 , that, here, these impeller blades  35 ′ are in the water position and are bent as far as possible inward or curved to the maximum extent. In this case, on account of a stop, not illustrated here, they reach only insignificantly beyond the diameter of the impeller  18  or of the impeller disk  30 ,  32 . In this case, care must be taken, in the design of the impeller  18  or of the overall pump  12 , in particular with the heating system  28 , to ensure that the impeller blades  35 , in the position bent out to the maximum extent according to  FIG. 2 , do not brush on the inside against the pump casing  13  or heating system  28 . 
         [0035]      FIG. 3  illustrates in a slight enlargement how the impeller blades  35  are designed, without illustrating the impeller cover disk  32 . In the radially inner region or at the radially inner end, they have a fastening region  37  in which they are firmly connected over a certain length to the impeller bottom disk  30 . This firm connection may, on the one hand, be produced in one piece and, on the other hand, be a firm bonding or other stable and permanent fastening, for example by means of a positive connection, such as plugging in or the like. The impeller blade  35  extends outward from the fastening region  37 , illustrating by hatching, and is in this case no longer connected to the impeller bottom disk  30 . The free region of the impeller blade  35  may in this case have a very slight clearance with respect to the impeller bottom disk  30 , in particular also with respect to the impeller cover disk  32 , above all in the radially outer region, for example in the amount of a few tenths of a millimeter. 
         [0036]    As regards the impeller blade  35 , a shaping or stipulated curvature, as in the air position, is illustrated by reference symbol  35 . This means that the impeller blade  35  is in the air position, without being influenced by external force. When it is bent in the direction of rotation of the impeller  18  counterclockwise opposite to this direction of rotation, that is to say to the right, it assumes the more highly curved water position  35 ′. The curvature illustrated arises, in particular, when the impeller  18  conveys water in the pump  12  and the water resistance or the considerably higher force necessary for this curves the impeller blade  35  to a greater extent. As soon as this higher force lapses, the impeller blade  35  moves back into the air position again as the impeller blade  35  due to its intrinsic spring force. 
         [0037]    As a guide device for guiding the impeller blade  35 , there is provided in the impeller bottom disk  30  a slot  39  which extends over a region near the outer circumference and at the same time reaches virtually to the impeller blade  35  in the air position and to the impeller blade  35 ′ in the water position. A pin-like sliding element  40  is mounted in the slot  39  and can be moved along the slot  39 . Advantageously, a corresponding slot is located above the slot  39  on the underside of the impeller cover disk  32 , so that the sliding element is secured on both sides. For safe and tilt-free guidance, the sliding element  40  may have a kind of elongate carriage body slightly curved correspondingly to the slot  39  and having a pin, for guidance in one or in both slots of the impeller disks  30  and  32 , two carriage bodies then being connected by the pin. This pin of the sliding element  40  runs, as illustrated, in a longitudinal slot  36  in the impeller blades  35 . The slots  36  and  39  may in this case, together with a sliding element  40 , be designed such that, in the air position of the impeller blade  35 , the sliding element  40  is located at the very bottom of the slot  39  and as far radially inward as possible on the longitudinal slot  36  of the impeller blade  35 . In the water position of the impeller blade  35 ′, the sliding element  40  is located at the very top of the slot  39  and as far to the outside as possible on the longitudinal slot  36 . This therefore defines the state curved to the maximum extent of the impeller blade  35 ′. In possible intermediate positions, the sliding element  40 , on the one hand, defines a certain guidance or stipulated shape of the impeller blade  35 . Furthermore, as illustrated in  FIG. 3 , it may, above all, represent as it were limit stops for the water position, on the one hand, and the air position, on the other hand. To be precise, the impeller blade  35  cannot be bent more sharply either in the direction of rotation or opposite to the direction of rotation of the impeller  18 . 
         [0038]    Furthermore, regarding the two positions according to  FIG. 3 , it must be said that, because of the lever arm resulting from force being applied to the impeller blade, the bend or curvature of the latter mainly takes place in the inner region near the fastening region  37 . The exact form of the curvature or the course of the curvature can be influenced by various adjustable material properties of the impeller blade  35  and also by shaping, for example by the longitudinal slots  36  or the like, for example also by the cross section changing along the longitudinal course. 
         [0039]    For the impeller blades  35 , care must also be taken to ensure that, as can be seen from  FIG. 1 , they should, on the one hand, have a shape such that they run essentially near to the impeller bottom disk  30  and impeller cover disk  32 , specifically in both positions. For this purpose, however, care should then be taken to ensure that the clearance between the two impeller disks  30  and  32  in the region in which the impeller blades  35  curve in and out between them is such that the movement of the impeller blades is not impaired. 
         [0040]    Alternatively to a curvature, stipulated virtually by shaping, of the impeller blade  35  into the air position according to  FIG. 3  with minimum curvature, there could also be provision whereby, in the normal or nonloaded state, the impeller blade  35 ′ assumes the water position and is therefore curved to the maximum extent. If air is to be conveyed by the pump  12 , the rotational speed at the motor  15  is greatly increased, for example doubled or tripled, which greatly increases the centrifugal forces acting upon the impeller blades  35  and may in this case have the effect that, according to  FIG. 3 , they bend or are set up into the air position to a greater extent. This may sometimes also be reinforced in that regions of higher mass are provided or even additional weights are attached in the region of the outer free ends of the impeller blades  35 . If water is then conveyed again in the pump  12  with a lower rotational speed, the impeller blades  35  move back into the highly curved water position again, on the one hand, because of the diminishing centrifugal force and, on the other hand, on account of the stipulated shape. 
         [0041]      FIG. 4  illustrates, in a modification for an impeller  118 , how the impeller blades  135  arranged on an impeller bottom disk  130  may be designed to be solid or without the longitudinal slots according to  FIG. 3 . This therefore means that the impeller blades  135  have no guidance of their movement between the minimally curved air position set out as far as possible, on the one hand, and the water position curved to the maximum extent to the right, as impeller blades  135 ′. Only a first stop  141  for the air position is provided on the impeller bottom disk  130 . Similarly, a second stop  142  for the water position is provided on the impeller bottom disk  130 . These stops  141  and  142  have the effect that the movement or curvature of the impeller blade  135  is limited in a similar way to that by the sliding element  40 , together with the slot  39 , according to  FIG. 3 . 
         [0042]    This design of the impeller disks  130  and  132  and of the impeller blades  135  themselves is somewhat simpler than according to  FIG. 3 . The stops  141  and  142  may either extend only a little way over the impeller bottom disk  130 , in order to bring about water resistance or give rise to turbulences as little as possible. Alternatively, they may also run over the substantial height or overall height of the impeller blades  135 , in particular toward the opposite impeller cover disk  132 . Thus, on the one hand, they ensure good distortion-free bearing contact of the impeller blades  135 . On the other hand, they can also serve for connecting the two impeller disks  130  and  132  to one another. 
         [0043]    As regards a possible preshaping or precurving of the guide blades of the exemplary embodiment of  FIG. 4 , the same can be said as for  FIG. 3 , that is to say they have the same possibilities. The guidance, omitted in the exemplary embodiment according to  FIG. 4 , by means of a sliding element and slot changes nothing in that regard.