Abstract:
A pump arrangement, in particular a magnetic clutch pump arrangement, is provided. The pump arrangement includes a pump housing containing an impeller shaft, an impeller, a casing cover adjacent to the impeller and supporting a plain bearing arrangement. The pump arrangement also includes a containment shell which seals an enclosed chamber within the inner chamber of the pump housing. The plain bearing arrangement includes first and second bearing sleeves connected to the impeller shaft, a first bearing bush which cooperates with the first bearing sleeve via a radial bearing surface and is connected to the pump housing or to a component secured to the pump housing a second bearing bush which cooperates with the second bearing sleeve via a radial bearing surface and is connected to the pump housing or to a component secured to the pump housing, and a retainer ring mounted between the first and second bearing sleeves. The retainer ring has, in the end surface facing the first bearing bush a first annular groove which receives a first axial bearing ring, and in the end surface facing the second bearing bush a second annular groove which receives a second axial bearing ring.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of PCT International Application No. PCT/EP2014/058669, filed Apr. 29, 2014, which claims priority under 35 U.S.C. §119 from German Patent Application No. 10 2013 208 460.9, 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 a magnetic clutch pump arrangement. 
         [0003]    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 is mounted by way of a plain bearing arrangement and which can be driven in rotation about an axis of rotation, having an impeller arranged on one end of the impeller shaft, a first bearing sleeve connected non-rotationally to the impeller shaft, a second bearing sleeve connected non-rotationally to the impeller shaft, a first bearing bushing which interacts by way of a radial bearing surface with the first bearing sleeve and which is connected non-rotationally to the pump casing or to a component fastened to the pump casing, a second bearing bushing which interacts by way of a radial bearing surface with the second bearing sleeve and which is connected non-rotationally to the pump casing or to a component fastened to the pump casing, and a retaining ring arranged between the first and second bearing bushings. 
         [0004]    European patent document no. EP 0 771 956 A1 has disclosed a magnetic clutch pump of said type with a plain bearing arrangement, in the case of which the static bearing parts are received in a bearing ring carrier, referred to as outer casing, and the bearing parts which rotate about the axis of rotation are positioned on the shaft. Here, the axial bearings are each assigned a static bearing part from the outside. This has the disadvantage that the impeller and the bearing bushing arranged closest to the impeller are spaced apart to a relatively great extent, and thus there is a relatively large spacing between said bearing bushing and the radial force that arises at the impeller. Furthermore, an exchange of the static bearing parts is possible only with great outlay and using special tools. 
         [0005]    It is the object of the invention to further develop a generic pump arrangement such that the lubrication of the axial bearing is further improved, the radial bearing forces under given loads are reduced, and ease of servicing is increased. 
         [0006]    The object of the invention is achieved in that a first ring groove, which receives a first axial bearing ring, is formed in the retaining ring on the face side facing toward the first bearing bushing, and a second ring groove, which receives a second axial bearing ring, is formed in the retaining ring on the face side facing toward the second bearing bushing. 
         [0007]    Owing to the positioning of the axial bearing rings between the first and second bearing bushings, the lubrication and cooling of the axial bearing arrangements thus formed is optimized in relation to the prior art. Likewise, the two axial bearing arrangements are thus situated at a position with the least shaft bending, whereby axial bearing tilting is reduced in relation to the prior art, and the contact ratio is increased. 
         [0008]    In an advantageous refinement, the first bearing sleeve and the first bearing bushing are arranged in an opening of the casing cover. 
         [0009]    In this way, it is possible for the first bearing sleeve and first bearing bushing to be positioned closer to the impeller, whereby the radial forces in the bearing can be reduced, and a lower likelihood of bearing failure at operating points that are critical with regard to radial thrust is realized. 
         [0010]    To achieve secure seating of the axial bearing rings, it is provided, in a preferred refinement of the invention, that the first axial bearing ring is clamped in the first ring groove by way of an undular washer, and the second axial bearing ring is clamped in the second ring groove by way of an undular washer. 
         [0011]    In a preferred refinement of the invention, for optimum lubrication and cooling of the plain bearing arrangement, it is provided that, in the retaining ring, there is formed at least one bore which connects the first ring groove to a further ring groove formed in the retaining ring in a region facing toward the impeller shaft. 
         [0012]    For the same reason, according to the invention, in the retaining ring, there is formed at least one bore which connects the second ring groove to the ring groove formed in the retaining ring in the region facing toward the impeller shaft. 
         [0013]    For simple and inexpensive assembly, in an advantageous refinement of the invention, an opening in a casing cover of the pump casing has an opening region of increased diameter, in which opening region there is formed an encircling groove which receives a tolerance ring, and in which opening region the first bearing bushing is positioned and connected non-rotationally to the casing cover by way of the tolerance ring. 
         [0014]    Furthermore, it is expediently the case that an opening in the bearing ring carrier has an opening region of increased diameter, in which opening region there is formed an encircling groove which receives a tolerance ring, and in which opening region the second bearing bushing is accommodated and connected non-rotationally to the bearing ring carrier by way of the tolerance ring. 
         [0015]    An arrangement of the first bearing bushing in the casing cover and of the second bearing bushing in the bearing ring carrier has the advantage that the plain bearing arrangement or parts thereof can be exchanged in an easy manner with regard to servicing, without the use of special tools. 
         [0016]    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 
         [0017]      FIG. 1  shows a longitudinal section through a magnetic clutch pump arrangement having a plain bearing arrangement according to an embodiment of the invention, and 
           [0018]      FIG. 2  shows a plain bearing arrangement corresponding to  FIG. 1  in an enlarged illustration. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  shows 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 hydraulics 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 . 
         [0020]    The hydraulics 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 hydraulics 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 hydraulics 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 . 
         [0021]    A containment can  10  is fastened to that side of the casing cover  4  which is opposite from the hydraulics 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, with respect to the interior space  11 . 
         [0022]    An impeller shaft  13  which is rotatable about an axis of rotation A extends from a flow chamber  14 , which is delimited by the hydraulics casing  3  and by the casing cover  4 , into the chamber  12  through an opening  15  provided in the casing cover  4 . 
         [0023]    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 . 
         [0024]    Between the impeller  16  and the inner rotor  17  there is arranged a plain bearing arrangement  19  which is operatively connected to the impeller shaft  13 , which can be driven in rotation about the axis of rotation A. 
         [0025]    A drive motor, preferably an electric motor, which is not illustrated drives a drive shaft  20 . The drive shaft  20 , which can be driven about the axis of rotation A, is arranged substantially coaxially with the impeller shaft  13 . The drive shaft  20  extends through the bearing cover  7  and through the bearing carrier  6  and is mounted in two ball bearings  21 ,  22  which are accommodated in the bearing carrier  6 . On the free end of the drive shaft  20  there is arranged an outer rotor  24 , which bears multiple magnets  23 . The magnets  23  are arranged on that side of the outer rotor  24  which faces toward the containment can  10 . The outer rotor  24  extends at least partially over the containment can  10  and interacts with the inner rotor  17  such that the rotating outer rotor  24 , by way of magnetic forces, sets the inner rotor  17  and thus likewise the impeller shaft  13  and the impeller  16  in rotation. 
         [0026]    The plain bearing arrangement  19  illustrated on an enlarged scale in  FIG. 2  comprises a first retaining ring  25 , which is arranged on the impeller shaft  13  and which bears by way of one side against the impeller  16 . A first bearing sleeve  26 , which has likewise been pushed onto the impeller shaft  13 , bears against that side of the retaining ring  25  which is situated opposite the impeller  16 . The first bearing sleeve  26  is surrounded by a first bearing bushing  27 , which is connected non-rotationally to the casing cover  4 . The first bearing sleeve  26 , which is situated close to the impeller  16 , and the first bearing bushing  27 , which is situated close to the impeller  16 , are in this case arranged entirely, or at least partially or predominantly, in the opening  15  of the casing cover  4 . The opening  15  of the casing cover  4  has an opening region  28  of increased diameter, in which opening region there is formed an encircling groove  30  which receives a tolerance ring  29 , wherein the bearing bushing  27  positioned in the opening region  28  is connected non-rotationally to the casing cover  4  in a secure manner by way of the tolerance ring  29 . 
         [0027]    A second retaining ring  31 , which has been pushed onto the impeller shaft  13 , bears against that side of the bearing sleeve  26  which is situated opposite the retaining ring  25 . In the retaining ring  31  there is formed a first ring groove  32  which points toward the first bearing bushing  27  and in which a first axial bearing ring  33  is arranged. The first bearing bushing  27  and first axial bearing ring  33  are arranged so as to be situated substantially opposite one another. On the side situated opposite the first ring groove  32 , the retaining ring  31  has a second ring groove  34  in which a second axial bearing ring  35  is accommodated. In the embodiment shown, the retaining ring  31  is of single-part form. In an alternative embodiment, the retaining ring  31  may be formed in two parts, wherein both retaining ring parts have in each case only one ring groove  32  and  34  respectively. The first axial bearing ring  33  is clamped in the first ring groove  32  by way of an undular washer  36 . In the same way, the second axial bearing ring  35  is clamped in the second ring groove  34  by way of a further undular washer  37 . 
         [0028]    A second bearing sleeve  38  arranged on the impeller shaft  13  bears against that side of the retaining ring  31  which is situated opposite the first bearing sleeve  26 , and said second bearing sleeve is surrounded by a second bearing bushing. The second bearing bushing  39  and second axial bearing ring  35  are arranged so as to substantially face one another. A third retaining ring  40 , which has been pushed onto the impeller shaft  13 , bears, at the side facing away from the retaining ring  31 , against the second bearing sleeve  38 . 
         [0029]    As can be seen from  FIGS. 1 and 2 , the plate spring pack  41  is arranged between the retaining ring  40  and the shaft section  13   a  and exerts a spring force on the clamped assembly composed of impeller  16 , an impeller nut  43  which fastens the impeller  16  to the impeller shaft  13  via a disk  42 , retaining ring  25 , first bearing sleeve  26 , retaining ring  31 , second bearing sleeve  38 , retaining ring  40  and inner rotor  17  in such a way that the clamped assembly is held in abutment, in particular by way of the inner rotor  17 , with a certain degree of elasticity against an abutment surface  44  which arises owing to the different diameters of the shaft sections  13   a  and  13   b , wherein the diameter of the shaft section  13   b  is greater than the diameter of the shaft section  13   a  and the diameter of the shaft section  13   a  is greater than the diameter of that part of the impeller shaft  13  which adjoins the shaft section  13   a  at the side facing away from the shaft section  13   b . The clamped assembly comprises substantially the components which rotate with the impeller shaft  13  about the axis of rotation A. 
         [0030]    Owing to differently acting axial thrust forces during the operation of the pump arrangement  1 , either the first axial bearing ring  33  abuts against the first bearing bushing  27 , wherein first axial bearing ring  33  and first bearing bushing  27  form a first axial bearing arrangement  45 , or the second axial bearing ring  35  abuts against the second bearing bushing  39 , wherein second axial bearing ring  35  and second bearing bushing  39  form a second axial bearing arrangement  46 . 
         [0031]    A bearing ring carrier  47  is fastened, coaxially with respect to the axis of rotation A, by way of a flange-like region  48  to the casing cover  4  by means of a screw connection (not illustrated), and said bearing ring carrier extends into the chamber  12 . Here, said bearing ring carrier substantially surrounds the retaining ring  31  with the axial bearing rings  33 ,  35 , the second bearing sleeve  38 , the second bearing bushing  39  and, at least in part, the retaining ring  40 . From the flange-like region  48  to its free end  49 , the outer diameter of the bearing ring carrier  47  decreases in sections. The bearing ring carrier  47  has an interior region  50  within which the retaining ring  31  is arranged. On the free end  49 , the bearing ring carrier  47  has an opening  51  through which the impeller shaft  13  extends, which opening has an opening region  52  of increased diameter situated adjacent to the interior region  50 , in which opening region there is formed an encircling groove  54  which receives a tolerance ring  53 . The second bearing bushing  39 , which is accommodated in the opening region  52 , is connected rotationally conjointly to the bearing ring carrier  47  in a secure manner by way of the tolerance ring  53 . 
         [0032]    An abutment surface  55  is realized owing to the transition from the opening  15  to the opening region  28  of increased diameter, and an abutment surface  56  is realized owing to the transition from the opening  51  to the opening region  52  with increased diameter, which abutment surfaces hold the plain bearing arrangement  19  in its intended position. 
         [0033]    Passage openings  57 ,  58  are provided in the casing cover  4 , and passage openings  59 ,  60  are provided in the bearing ring carrier  47 . The passage openings  57 ,  58  connect the flow chamber  14  to the chamber  12  which is substantially surrounded by the containment can  10  and the casing cover  4 , and the passage openings  59 ,  60  connect the chamber  12  to the interior region  50  of the bearing ring carrier  47 . In the retaining ring  31  there is formed at least one bore  61  which connects the first ring groove  32  to a further ring groove  62  which is formed in the retaining ring  31  in the region facing toward the impeller shaft  13 . At least one bore  63  connects the second ring groove  34  likewise to the ring groove  62 . Furthermore, at least one axial groove  64  running parallel to the axis of rotation is situated in the first bearing bushing  27  on the radial bearing surface which interacts with the first bearing sleeve  26 , and an axial groove  65  is situated in the second bearing bushing  39  on the radial bearing surface which interacts with the second bearing sleeve  38 . 
         [0034]    Thus, for the cooling and lubrication of the plain bearing arrangement  19 , delivery medium can be extracted from the flow chamber  14  and supplied via the passage openings  57 ,  58 ,  59 ,  60  to the axial bearing rings  33 ,  35  and to the mutually assigned surfaces of the bearing sleeves  26 ,  38  and bearing bushings  27 ,  39 . Via the bores  61 ,  63 , the delivery medium is delivered into the ring groove  62 . Via at least one radial bore  66  formed in the impeller shaft  13 , the delivery medium is delivered into an axial duct (not illustrated), which extends through the entire impeller shaft  13  from one end to the other, and then back into the flow chamber  14 . If required, at least one further radial bore  67  is formed in the impeller shaft close to the retaining ring  40  or disk spring pack  41 , which at least one further radial bore is likewise connected to the axial duct extending through the impeller shaft  13 . Via at least one radial bore (not illustrated in the figures) in the retaining ring  40 , the delivery medium is delivered from the interior region  50  of the bearing ring carrier  48  to the at least one radial bore  67 . By virtue of the fact that the radial bores  66 ,  67  are arranged relatively far away from the impeller  16 , greater fatigue strength of the impeller shaft  13  is realized. 
         [0035]    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  Hydraulics 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  Plain bearing arrangement 
           20  Drive shaft 
           21  Ball bearing 
           22  Ball bearing 
           23  Magnet 
           24  Outer rotor 
           25  Retaining ring 
           26  First bearing sleeve 
           27  First bearing bushing 
           28  Opening region 
           29  Tolerance ring 
           30  Groove 
           31  Retaining ring 
           32  First ring groove 
           33  First axial bearing ring 
           34  Second ring groove 
           35  Second axial bearing ring 
           36  Undular washer 
           37  Undular washer 
           38  Second bearing sleeve 
           39  Second bearing bushing 
           40  Retaining ring 
           41  Plate spring pack 
           42  Disk 
           43  Impeller nut 
           44  Abutment surface 
           45  First axial bearing 
           46  Second axial bearing 
           47  Bearing ring carrier 
           48  Flange-like region 
           49  Free end 
           50  Interior region 
           51  Opening 
           52  Opening region 
           53  Tolerance ring 
           54  Groove 
           55  Abutment surface 
           56  Abutment surface 
           57  Passage opening 
           58  Passage opening 
           59  Passage opening 
           60  Passage opening 
           61  Bore 
           62  Ring groove 
           63  Bore 
           64  Axial groove 
           65  Axial groove 
           66  Radial bore 
           67  Radial bore 
         A Axis of rotation