Patent Publication Number: US-10323642-B2

Title: Pump motor with a fixed bearing

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates to a pump motor and its internal construction. The pump motor has a permanent magnet rotor, a containment shell, a wound stator, a motor housing, a pump head, and a shaft, which is secured in the containment shell on the one hand and in the pump head on the other hand, and a fixed bearing, which is pressed or injected into the permanent magnet rotor and rotatably mounts it on the shaft. 
     (2) Description of Related Art Including Information Disclosed Under 37 CFR 197 and 1.98 
     In combustion engines of motor vehicles, mechanical pumps driven by the crankshaft via a gear belt are generally provided as main cooling water pump. As a support or an alternative in a shut-off combustion engine, electric ancillary cooling water pumps are used, which are generally designed as electronically commutated direct-current motors. Main cooling water pumps can also be operated electrically. From DE 10 2011 079 226 B4 is known a generic pump, in which bearing bushes are used to mount the permanent magnet rotor on the shaft. In doing so, a running surface of the bearing can be deformed by a press-fitting process of the bearing bush into the permanent magnet rotor such that punctual or linear contacts of the bush with the shaft result. This effect is particularly pronounced in bearing bushes with different material thicknesses, as is the case in collar bushes. Such deformations generally result in increased bearing noises. For economic reasons, the tolerances for bearing bushes cannot be arbitrarily small, which is why undefined bearing pairings can occur, in which the shaft abuts non-uniformly over the bearing length and non-uniformities also occur during a rotation. 
     SUMMARY OF THE INVENTION 
     The task of the present invention is therefore to provide for a reliable and economically producible bearing of the permanent magnet rotor on the shaft in a generic pump motor, in which the bearing abutting uniformly against the shaft over the entire bearing length and during a complete rotation can be achieved, small angle errors can be compensated, and noises can be reduced. 
     According to the invention, the bearing consists of a press ring pressed into the permanent magnet rotor, a thrust ring accommodated rotatably on the shaft, and a ring disk-shaped hub. This results in a function separation of the individual bearing components. The press ring can and may deform slightly during the press-fitting process, the thrust ring retains its optimum shape for the running properties, and the ring disk-shaped hub constitutes the connecting element between the press ring and the thrust ring. The hub can deform slightly in a region close to the press ring but retains its shape in a region close to the thrust ring and does not transfer any deformation forces onto the thrust ring. 
     The fixed bearing can be particularly economically produced because the press ring, the thrust ring, and the hub form an integral component. In order to protect the thrust ring against deformations, it is advantageous to design the hub to be resilient so that its stiffness is not sufficient to transfer the press-fitting forces to the thrust ring. In order to ensure the resilience of the hub, the fixed bearing comprises an H-shaped or U-shaped ring cross section. The thickness of the disk-shaped hub can be selected according to the requirements. 
     In order to ensure good sliding properties even during axial force application, a thrust washer can be provided, which is accommodated on the shaft between the fixed bearing and the bearing accommodation sleeve. The thrust ring of the fixed bearing is located axially opposite the bearing accommodation sleeve or, if applicable, the thrust washer. 
     The fixed bearing is arranged between a hollow shaft and a bearing accommodation sleeve. When axial forces occur, the hub can act in a dampening manner as a result of its resilience since the press ring is radially offset to the thrust ring and only the press ring abuts against the hollow shaft. The fixed bearing is generally mounted up to the hollow shaft. The thrust ring is located freely opposite the hollow shaft. 
     The fixed bearing is preferably arranged radially between a permanent magnet and the shaft. In doing so, the fixed bearing is directly pressed into the permanent magnet. 
     The permanent magnet itself is connected in a form-fitted matter to the hollow shaft. The permanent magnet preferably consists of a plastic bonded rare-earth magnet, which is master molded directly on the hollow shaft. The form fit is established by a groove on the outer circumference of the hollow shaft or by recesses suitably formed in another manner. 
     The hollow shaft is connected to a pump impeller or integrally master molded with it. The impeller comprises pump vanes and can comprise a cover plate to improve efficiency. 
     In the region of the pump impeller, the hollow shaft comprises a spherical slide bearing, which interacts with a spherical counter bearing, which is held in a seat in the pump head. During operation, the spherical bearing surfaces function in such a way that self-centering takes place so that the bearing pairing assumes both an axial bearing function and a radial bearing function. This bearing type significantly improves the running smoothness. 
     It is suggested to construct the fixed bearing according to the invention from one bearing material. This can be a plastic interspersed with carbon fibers, a graphite material, a sintered metal, or something else. 
    
    
     
       DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The invention is better understood by reading the following Detailed Description of the Preferred Embodiments with reference to the accompanying drawing figures, in which like reference numerals refer to like elements throughout, and in which: 
         FIG. 1  is a sectional view of a pump motor according to the invention, and 
         FIG. 2  a spatial representation of the pump motor. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In describing preferred embodiments of the present invention illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. 
       FIG. 1  shows a sectional view of a pump motor  1  according to the invention, having a wound stator  4 , a permanent magnet rotor  2 , a containment shell  3 , a pump head  11 , a circuit board  20 , a support plate  21 , and a motor housing  10 . The stator  4 , the circuit board  20 , and the support plate  21  are located in a dry chamber  25 . The permanent magnet rotor  2  is rotatably mounted in a wet chamber  26  around a shaft  5 , which is secured on the one hand in the containment shell  3  and on the other hand in the pump head  11 . 
     The containment shell  3  comprises a containment shell flange  22 , and the pump head  11  comprises a pump head flange  23 . The motor housing  10  is designed to be pot-like and comprises a housing flange  24  and a connector shaft  29 . The pump head flange  23 , the containment shell flange  22 , and the housing flange  24  comprise screw eyes  27  with screws  28 , by means of which the pump head  11  and the containment shell  3  are screwed to the motor housing  10 . On both sides of the containment shell flange  22 , O-rings  30  are arranged as sealing elements. The circuit board  20  is populated with a plurality of SMD components. 
     Larger components, such as an electrolytic capacitor  31  and a choke coil  32 , are mechanically held on the support plate  21  but electrically connected on the circuit board  20 . The circuit board  20  and the support plate  21  are axially secured between the stator  4  and the motor housing  10 . The circuit board  20  is axially and radially secured between the stator  4  and the support plate  21 . In the support plate  21 , a contact element  33  is mechanically mounted, which is also electrically connected to the circuit board  20 . A bottom  34  of the pot-like motor housing  10  comprises an indentation  35 , which is adapted to the shape of the electrolytic capacitor  31 . 
     Illustrated furthermore is a pump impeller  16 , which is integral with a hollow shaft  12 . The pump impeller  16  comprises a cover plate  36 . The permanent magnet rotor  2  with the pump impeller  16  is rotatably mounted via a fixed bearing  6  and a spherical bearing  17  on the shaft  5  and between the pump head  11  and the containment shell  3 . The fixed bearing  6  is arranged between a hollow cylindrical permanent magnet  15  injected around the hollow shaft  12  and consisting of a plastic bonded material and the shaft  5 . The fixed bearing  6  mounts the pump impeller  2  radially as well as axially via the end of the hollow shaft  12  and a thrust washer  14 , which abuts against a bearing accommodation sleeve  13  integral with the containment shell  3 . The fixed bearing  6  comprises a press ring  7 , a thrust ring  8 , and a disk-shaped hub  9 . The thickness of the hub  9  is selected such that a radial deformation force, which acts on the hub  9  during a press-fitting process of the fixed bearing  6  into a central hollow space  37  of the permanent magnet  15 , is not transferred as far as the thrust ring  8  but brings about a deformation of the hub  9 . The hollow cylindrical shape of the thrust ring  8  is for the most part retained.  FIG. 1  furthermore shows a stator sheet package  38 , insulating elements  39 , and a stator winding  40 . The pump head  11  comprises a suction nozzle  41  and a discharge nozzle  42 . Spokes  43  in the suction nozzle  41  constitute a permeable connection between the suction nozzle  41  and the seat  19 . 
       FIG. 2  shows a spatial representation of a pump motor  1 , with the pump head  11  with suction nozzle  41  and discharge nozzle  42  and a pump head flange  23 , a containment shell flange  22  integral with the containment shell, the motor housing  10  with the housing flange  24 , the bottom  34 , the connector shaft  29 , and the indentation  35  for accommodating an electrolytic capacitor. Screw eyes  27  can also be seen, which are formed as extensions in the pump head flange  23 , the containment shell flange  22 , and the housing flange  24  and allow for a screw connection. On the motor housing  10  is formed an axial securing device  44 , which serves to axially secure an annular mounting device positioned around the motor housing  10 . 
     It is to be understood that the present invention is not limited to the illustrated embodiments described herein. Various types and styles of user interfaces may be used in accordance with the present invention without limitation. Modifications and variations of the above-described embodiments of the present invention are possible, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described. 
     LIST OF REFERENCE SYMBOLS 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                 1 
                 Pump motor 
               
               
                 2 
                 Permanent magnet rotor 
               
               
                 3 
                 Containment shell 
               
               
                 4 
                 Stator 
               
               
                 5 
                 Shaft 
               
               
                 6 
                 Fixed bearing 
               
               
                 7 
                 Press ring 
               
               
                 8 
                 Thrust ring 
               
               
                 9 
                 Hub 
               
               
                 10 
                 Motor housing 
               
               
                 11 
                 Pump head 
               
               
                 12 
                 Hollow shaft 
               
               
                 13 
                 Bearing accommodation sleeve 
               
               
                 14 
                 Thrust washer 
               
               
                 15 
                 Permanent magnet 
               
               
                 16 
                 Pump impeller 
               
               
                 17 
                 Spherical slide bearing 
               
               
                 18 
                 Spherical counter bearing 
               
               
                 19 
                 Seat 
               
               
                 20 
                 Circuit board 
               
               
                 21 
                 Support plate 
               
               
                 22 
                 Containment shell flange 
               
               
                 23 
                 Pump head flange 
               
               
                 24 
                 Housing flange 
               
               
                 25 
                 Dry chamber 
               
               
                 26 
                 Wet chamber 
               
               
                 27 
                 Screw eye 
               
               
                 28 
                 Screw 
               
               
                 29 
                 Connector shaft 
               
               
                 30 
                 O-ring 
               
               
                 33 
                 Contact element 
               
               
                 34 
                 Bottom 
               
               
                 35 
                 Indentation 
               
               
                 36 
                 Cover plate 
               
               
                 37 
                 Hollow space 
               
               
                 38 
                 Stator sheet package 
               
               
                 39 
                 Insulating element 
               
               
                 40 
                 Stator winding 
               
               
                 41 
                 Suction nozzle 
               
               
                 42 
                 Discharge nozzle 
               
               
                 43 
                 Spoke 
               
               
                 44 
                 Axial securing device