Abstract:
A pump arrangement, in particular a magnetic clutch pump arrangement, is provided. The pump arrangement includes a pump housing containing an impeller shaft, a containment shell which seals an enclosed chamber within the inner chamber of the pump housing, an impeller mounted on one end of the impeller shaft, an inner rotor mounted on the other end of the impeller shaft, an outer rotor which is mounted on the drive shaft and co-operates with the inner rotor, and an auxiliary impeller mounted in the chamber adjacent to a domed base of the containment can. The auxiliary impeller is secured to the inner rotor and includes vanes and impeller channels for circulation of media.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of PCT International Application No. PCT/EP2014/058706, filed Apr. 29, 2014, which claims priority under 35 U.S.C. §119 from German Patent Application No. 10 2013 007 849.0, filed May 8, 2013, the entire disclosures of which are herein expressly incorporated by reference. 
     
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
       [0002]    The invention relates to a pump arrangement, in particular magnetic clutch pump arrangement. The pump arrangement has an interior space formed by a pump casing a containment can which hermetically seals off a chamber surrounded by said containment can with respect to the interior space formed by the pump casing, an impeller shaft which can be driven in rotation about an axis of rotation, an impeller which is arranged on one end of the impeller shaft, an inner rotor arranged on the other end of the impeller shaft, an auxiliary impeller arranged in the chamber, and an outer rotor which interacts with the inner rotor. 
         [0003]    German patent document no. DE 27 54 840 A1 has disclosed a magnetic clutch pump arrangement of said type with an auxiliary impeller. The auxiliary impeller is of disk-shaped construction and is equipped with radial bores. However, said embodiment, with regard to its efficiency, constitutes an inefficient impeller or delivery variant, and lowers the overall efficiency of the pump arrangement. Furthermore, a not inconsiderable level of outlay is required to produce the auxiliary impeller. 
         [0004]    It is the object of the invention to provide a magnetic clutch pump arrangement with a forced-lubrication flow drive which is simple to produce and which exhibits improved efficiency. 
         [0005]    The object of the invention is achieved in that the auxiliary impeller is fastened to the inner rotor. 
         [0006]    Since the auxiliary impeller is fastened by way of its open side to that face side of the inner rotor which faces toward the base of the containment can, it is possible for the advantages of a closed channel-type impeller to be utilized by way of an open impeller, which is much easier to produce. Furthermore, the impeller does not have a hub and is easy to assemble and disassemble. 
         [0007]    In one refinement, the containment can has a main body with an open side and with a side which is situated opposite the open side and which is closed by way of a domed base, and the auxiliary impeller has a rear shroud, whose outer surface facing toward the base of the containment can has a domed form. 
         [0008]    By virtue of the fact that the domed form of the outer surface of the rear shroud substantially corresponds to the domed form of the base of the containment can, the dead space that is normally spanned by the domed base of the containment can is filled, whereby no additional axial structural space required by the magnetic clutch is taken up. Furthermore, the pressure resistance of the containment can is not unnecessarily reduced. 
         [0009]    To improve the flow guidance of the medium as it enters a fluid inlet region of the auxiliary impeller, a paraboloid-like elevation is ideally provided in the center of the rear shroud. 
         [0010]    In a further refinement, it is provided that, on the rear shroud, at a radial distance from the elevation, there are formed multiple raised portions which form vanes and corresponding impeller channels of the auxiliary impeller. 
         [0011]    In a further refinement, it is proposed that the impeller channels have a channel base which is similar in form to a rampant three-center arch. This leads to an improvement in flow guidance. 
         [0012]    In a further refinement of the invention, it is provided that the upper side of the vanes opposite the rear shroud, has a step close to the channel inlet edge. The step serves as an abutment shoulder and centering device for precise alignment of the auxiliary impeller fastened to the inner rotor. 
         [0013]    For simple and inexpensive production, the impeller shaft and the inner rotor form a cover shroud, situated opposite the rear shroud, of the auxiliary impeller. 
         [0014]    In a further advantageous refinement, in the raised portions which form the vanes, there are formed further impeller channels which extend in a radial direction from the outer lateral surface as far as a point close to the step. 
         [0015]    To improve the flow guidance of the medium, the further impeller channels have a channel base which, at least in part, has a domed form which corresponds substantially to the domed form of the outer surface of the rear shroud. 
         [0016]    According to the invention, the impeller shaft has an axial channel which is connected to the fluid inlet region of the auxiliary impeller. 
         [0017]    In the context of the invention, it is proposed that, in a further embodiment, in the inner rotor, there are provided fluid channels which issue into the further impeller channels of the auxiliary impeller. 
         [0018]    Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0019]      FIG. 1  shows the longitudinal section through a magnetic clutch pump arrangement having an auxiliary impeller according to an embodiment of the invention, 
           [0020]      FIG. 2  shows the longitudinal section through the magnetic clutch pump arrangement as per  FIG. 1  in a plane rotated through 90° in relation to  FIG. 1 , 
           [0021]      FIG. 3  shows an auxiliary impeller, corresponding to  FIG. 1 , in an enlarged illustration, 
           [0022]      FIG. 4  is a detailed three-dimensional illustration of the auxiliary impeller as per  FIG. 3 , 
           [0023]      FIG. 5  is a detailed three-dimensional illustration of a further embodiment of the auxiliary impeller according to the invention, 
           [0024]      FIG. 6  shows a longitudinal section through a magnetic clutch pump arrangement having an auxiliary impeller according to the invention as per  FIG. 5 , 
           [0025]      FIG. 7  shows the longitudinal section through a magnetic clutch pump arrangement as per  FIG. 6 , with an inner rotor rotated through 45° in relation to  FIG. 6 , and 
           [0026]      FIG. 8  shows the longitudinal section through the magnetic clutch pump arrangement as per  FIG. 6 , in a plane rotated through 90° in relation to  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0027]      FIGS. 1 and 2  show a pump arrangement  1  in the form of a magnetic clutch pump arrangement. The pump arrangement  1  has a multi-part pump casing  2  of a centrifugal pump, which pump casing comprises a hydraulic casing  3  in the form of a spiral casing, a casing cover  4 , a bearing carrier cage  5 , a bearing carrier  6  and a bearing cover  7 . 
         [0028]    The hydraulic casing  3  has an inlet opening  8  for the intake of a delivery medium and has an outlet opening  9  for the discharge of the delivery medium. The casing cover  4  is arranged on that side of the hydraulic casing  3  which is situated opposite the inlet opening  8 . The bearing carrier cage  5  is fastened to that side of the casing cover  4  which is opposite from the hydraulic casing  3 . The bearing carrier  6  is mounted on that side of the bearing carrier cage  5  which is situated opposite the casing cover  4 . The bearing cover  7  in turn is fastened to that side of the bearing carrier  6  which is opposite from the bearing carrier cage  5 . 
         [0029]    A containment can  10  is fastened to that side of the casing cover  4  which is opposite from the hydraulic casing  3 , and said containment can extends at least partially through an interior space  11  delimited by the pump casing  2 , in particular by the casing cover  4 , by the bearing carrier cage  5  and by the bearing carrier  6 . The containment can  10  hermetically seals off a chamber  12 , which is enclosed by said containment can and by the casing cover  4 , with respect to the interior space  11 . 
         [0030]    An impeller shaft  13  which is rotatable about an axis of rotation A extends from a flow chamber  14 , which is delimited by the hydraulic casing  3  and by the casing cover  4 , into the chamber  12  through an opening  15  provided in the casing cover  4 . 
         [0031]    An impeller  16  is fastened to a shaft end, situated within the flow chamber  14 , of the impeller shaft  13 , and an inner rotor  17  arranged within the chamber  12  is arranged on the opposite shaft end, which has two shaft sections  13   a,    13   b  with increasing diameters in each case. The inner rotor  17  is equipped with multiple magnets  18  which are arranged on that side of the inner rotor  17  which faces toward the containment can  10 . An auxiliary impeller  20  is fastened to the inner rotor  17  by way of screws  19  or other suitable fastening means. 
         [0032]    Between the impeller  16  and the inner rotor  17  there is arranged a bearing arrangement  21  which is operatively connected to the impeller shaft  13 , which can be driven in rotation about the axis of rotation A. 
         [0033]    A drive motor, preferably an electric motor, which is not illustrated drives a drive shaft  22 . The drive shaft  22 , which can be driven about the axis of rotation A, is arranged substantially coaxially with respect to the impeller shaft  13 . The drive shaft  22  extends through the bearing cover  7 , through the bearing carrier  6 , and at least partially into the bearing carrier cage  5 . The drive shaft  22  is mounted in two ball bearings  23 ,  24  which are accommodated in the bearing carrier  6 . On the free end of the drive shaft  22  there is arranged an outer rotor  26 , which bears multiple magnets  25 . The magnets  25  are arranged on that side of the outer rotor  26  which faces toward the containment can  10 . The outer rotor  26  extends at least partially over the containment can  10  and interacts with the inner rotor  17  such that the rotating outer rotor  26 , by way of magnetic forces, sets the inner rotor  17  and thus likewise the impeller shaft  13  and the impeller  16  in rotation. 
         [0034]    The containment can  10 , illustrated on an enlarged scale in  FIG. 3 , has a substantially cylindrical main body  27 . The main body  27  is open on the side facing toward the casing cover  4 , and is closed by way of a domed base  28  on the side situated opposite the open side. On the open side, there is arranged a ring-like attachment flange  29  which is formed integrally with the main body  27  or which is fastened to the latter by welding or other suitable fastening means or devices, for example screws, rivets or the like. The attachment flange  29  has multiple bores  30  which extend parallel to the axis of rotation A and through which screws  31  can be passed and screwed into corresponding threaded bores in the casing cover  4 . The base  28  of the containment can  10  is formed by a substantially spherical segment-shaped spherical cap region  32  and an outer rim region  33  which forms the transition region between main body  27  and spherical cap region  32 . 
         [0035]    As can be seen from  FIGS. 3 and 4 , the auxiliary impeller  20  has a rear shroud  34 , whose outer surface, facing toward the base  28  of the containment can  10 , has a domed form. The domed form of the outer surface of the rear shroud  34  substantially corresponds to the domed form of the base  28  of the containment can  10 . In the center of the rear shroud  34 , a paraboloid-like elevation  35  is provided in a fluid inlet region  36 . Furthermore, multiple raised portions are formed on the rear shroud  34  at a radial distance from the elevation  35 , which raised portions form vanes  37  with a channel inlet edge  38 , facing toward the elevation  35 , and corresponding impeller channels  39  of the auxiliary impeller  20 . The elevation  35  is conducive to improving the flow guidance of the medium as it enters the impeller channels  39  of the auxiliary impeller  20 . In the exemplary embodiment shown, the vanes  37  extend in curved fashion from the fluid inlet region  36  to an outer lateral surface  40  of the auxiliary impeller  20 . The impeller channels  39  have a channel base  41 , which in turn has a domed form substantially corresponding to the domed form of the outer surface of the rear shroud  34 . The channel base  41  of the impeller channels  39  is, in the longitudinal section shown, similar in form to a rampant three-center arch, as illustrated in  FIG. 6 . The impeller channels  39  have a first width W 1  at the fluid inlet region  36  and have a second width W 2  at the outer lateral surface  40 , wherein the second width W 2  is greater than the first width W 1  or at least corresponds to the first width W 1 . 
         [0036]    The upper side of the vanes  37  has a step  42  close to the channel inlet edge  38 , which step serves as an abutment shoulder and centering device for the auxiliary impeller  20  fastened to the inner rotor  17 . A cover shroud which is situated opposite the rear shroud  34  and which closes off the impeller channels  39  formed between the vanes  37  can be dispensed with, as the impeller shaft  13  and the inner rotor  17  form the cover shroud of the auxiliary impeller  20 . Owing to its semi-open construction, the auxiliary impeller  20  is easy to produce both by casting, as it is easily demoldable, and by mechanical machining, as the impeller channels can be easily milled out. 
         [0037]    At a distance radially outward from the steps  42 , installation holes  43  are provided which extend through the rear shroud  34  and the vanes  37 , through which installation holes the screws  19  are passed and screwed into the threaded bores  44  formed on that side of the inner rotor  17  which faces toward the base  28  of the containment can  10 . The auxiliary impeller  20  can thus be fastened by way of its open side to that face side of the inner rotor  17  which faces toward the base  28  of the containment can  10 . On the side situated opposite the channel inlet edge  38 , each vane  37  preferably has at least one recess  45 . An additional pressure increase is generated in this way. 
         [0038]    As shown in  FIG. 2 , in the casing cover  4 , there are provided at least one passage opening  46  and, in a bearing ring carrier  47  which fixes the bearing arrangement  21 , at least one radial passage opening  48 . The passage opening  48  extends through a flange-like region  49  by which the bearing ring carrier  47 , which is positioned coaxially with respect to the axis of rotation A and which extends into the chamber  12 , is fastened to the casing cover  4  by way of a screw connection (not illustrated). The passage openings  46  and  48  connect the flow chamber  14  to an inner region  50  of the bearing ring carrier  47 . 
         [0039]    Thus, for the cooling and lubrication of the bearing arrangement  21 , delivery medium can be extracted from the flow chamber  14  and supplied by the passage openings  46  and  48  to the bearing arrangement  21 . Via at least one radial bore  51 , the delivery medium is delivered from the inner region  50  into an axial channel  52 , which extends from a region of the impeller shaft  13  surrounded by the bearing arrangement  21  to that end of the impeller shaft  13  which is situated within the chamber  12 , and thus to the auxiliary impeller  20 . The axial channel  52  is thus connected to the fluid inlet region  36  of the auxiliary impeller  20 . If necessary, at least one further radial bore  53  is formed which is likewise connected to the axial channel  52  formed in the impeller shaft  13 . The auxiliary impeller  20  delivers the medium used for cooling and lubrication radially outward into the chamber  12 , from where said medium is delivered back into the flow chamber  14  via multiple axial passage openings  54  formed in the flange-like region  49  and passage openings  55  formed in the casing cover  4 , said passage openings being shown in  FIG. 1 . 
         [0040]      FIGS. 5 to 8  show a further exemplary embodiment of the invention. The auxiliary impeller  20 , illustrated in detail in  FIG. 5 , has vanes  37  which are formed by raised portions on the rear shroud  34  and which define impeller channels  39  which extend radially outward from the fluid inlet region  36 . In the exemplary embodiment shown, the vanes  37  extend rectilinearly from the fluid inlet region  36  to the outer lateral surface  40  of the auxiliary impeller  20 . The impeller channels  39  have a first width W 1  at the fluid inlet region  36  and a second width W 2  at the outer lateral surface  40 , wherein the second width W 2  is greater than the first width W 1  or at least corresponds to the first width W 1 . 
         [0041]    Further impeller channels  56  are formed in the raised portions which form the vanes  37 , which further impeller channels extend in the radial direction likewise in substantially straight form, that is to say without a curvature or without a significant curvature, from the outer lateral surface  40  to a point close to the step  42 , and which further impeller channels have a channel base  57  which, at least in part, has a domed form which substantially corresponds to the domed form of the outer surface of the rear shroud  34 . As viewed in longitudinal section, the channel base  57  of the impeller channels  56  is similar in form to a rampant three-center arch, as illustrated in  FIG. 7 . The impeller channels  56  widen toward the outer lateral surface  40  proceeding from the region adjacent to the step  42 , and said impeller channels have a first width W 3  at a fluid inlet region  56   a  and a second width W 4  at the outer lateral surface  40 , wherein the second width W 4  is greater than the first width W 3  or at least corresponds to the first width W 3 . 
         [0042]      FIGS. 6 to 8  show a pump arrangement  1  which is equipped with an auxiliary impeller  20  as illustrated in  FIG. 5 . Here, the view in  FIGS. 6 and 7  corresponds to the view in  FIG. 1 . The view in  FIG. 8  corresponds to the view in  FIG. 2 . As can be seen from  FIG. 6 , the at least one radial bore  53  leads into an axial channel  52  which is shorter than in  FIGS. 1 and 2 . Furthermore, the bearing ring carrier  47  has fluid channels  58  running parallel to the axis of rotation A, which fluid channels connect the inner region  50  of the bearing ring carrier  47  to the chamber  12  which is enclosed by the containment can  10  and by the casing cover  4 . 
         [0043]      FIG. 7  shows the pump arrangement  1  shown in  FIG. 6  with an inner rotor  17  rotated through 45° about the axis of rotation A. In the inner rotor  17  there are provided fluid channels  59  which are arranged approximately at the same radial distance from the axis of rotation A as the fluid channels  58  of the bearing ring carrier  47 , and which are thus substantially in alignment with said fluid channels  58  at least in the position illustrated. The fluid channels  59  issue into the impeller channels  56  of the auxiliary impeller  20 , which is arranged on that face side of the inner rotor  17  which faces toward the base  28  of the containment can  10 . 
         [0044]    For the cooling and lubrication of the bearing arrangement  21 , delivery medium is extracted from the flow chamber  14  and, as shown in  FIG. 8 , is supplied to the bearing arrangement  21  via the at least one passage opening  46  in the housing cover  4  and via the at least one passage opening  48  in the flange-like region  49  of the bearing ring carrier  47 . Via the at least one radial bore  53 , the delivery medium is delivered from the inner region  50  of the bearing ring carrier  47  into the axial channel  52  and to the auxiliary impeller  20 . By way of the impeller channels  39 , the auxiliary impeller  20  delivers the medium used for cooling and lubrication radially outward into the chamber  12 . 
         [0045]    At the same time, as per  FIG. 7 , the delivery medium extracted from the flow chamber  14  is delivered from the inner region  50  of the bearing ring carrier  47 , via the fluid channels  59  formed in the inner rotor  17 , into the impeller channels  56  of the auxiliary impeller  20 , and radially outward into the chamber  12 . 
         [0046]    From the chamber  12 , the medium is delivered back into the flow chamber  14  via the at least one passage opening  55  (shown in  FIGS. 6 and 7 ) formed in the casing cover  4 . 
         [0047]    In the exemplary embodiments shown, the auxiliary impeller  20  is shown either with the impeller channels  39  or with the impeller channels  39  and the impeller channels  56 . It is self-evident that the auxiliary impeller  20  may also be equipped only with the impeller channels  56 . 
         [0048]    The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof. 
       LIST OF REFERENCE DESIGNATIONS 
       [0000]    
       
           1  Pump arrangement 
           2  Pump casing 
           3  Hydraulic casing 
           4  Casing cover 
           5  Bearing carrier cage 
           6  Bearing carrier 
           7  Bearing cover 
           8  Inlet opening 
           9  Outlet opening 
           10  Containment can 
           11  Interior space 
           12  Chamber 
           13  Impeller shaft 
           13   a  Shaft section 
           13   b  Shaft section 
           14  Flow chamber 
           15  Opening 
           16  Impeller 
           17  Inner rotor 
           18  Magnet 
           19  Screw 
           20  Auxiliary impeller 
           21  Bearing arrangement 
           22  Drive shaft 
           23  Ball bearing 
           24  Ball bearing 
           25  Magnet 
           26  Outer rotor 
           27  Main body 
           28  Base 
           29  Attachment flange 
           30  Bore 
           31  Screw 
           32  Spherical cap region 
           33  Rim region 
           34  Rear shroud 
           35  Elevation 
           36  Fluid inlet region 
           37  Vane 
           38  Channel inlet edge 
           39  Impeller channel 
           40  Outer lateral surface 
           41  Channel base 
           42  Step 
           43  Installation hole 
           44  Threaded bore 
           45  Recess 
           46  Passage opening 
           47  Bearing ring carrier 
           48  Passage opening 
           49  Flange-like region 
           50  Inner region 
           51  Radial bore 
           52  Axial channel 
           53  Radial bore 
           54  Passage opening 
           55  Passage opening 
           56  Impeller channel 
           57  Channel base 
           58  Fluid channel 
           59  Fluid channel 
         A Axis of rotation