Abstract:
An electrically commutated DC motor ( 1 ) for a liquid pump ( 2 ) with a pump housing ( 3 ) with a suction connector ( 4 ) and a pressure connector ( 5 ) for connection to a hydraulic circuit, an essentially disk-like pump rotor ( 6 ) mounted to rotate in the pump housing, consisting of an impeller ( 7 ) with several pump vanes and a permanent magnet ( 8 ), a partition ( 11 ) separating a pump space ( 9 ) from a dry space ( 10 ), the partition being arranged in an axial gap ( 12 ) between the pump rotor ( 6 ) and several axially aligned stator poles ( 14 ), each provided with an insulation element ( 15 ) and stator windings ( 16 ). The task of the present invention is to configure a DC motor, so that it can be installed simply and reliably, is designed particularly robust and therefore has very high lifetime.

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The invention concerns an electrically commutated DC motor for a liquid pump with a pump housing with a suction connector and a pressure connector for connection to a hydraulic circuit, an essentially disk-shaped pump rotor mounted to rotate in the pump housing, consisting of an impeller with several pump vanes and a permanent magnet, a partition separating a pump space from a dry space, the partition being arranged in an axial gap between the pump rotor and several axially aligned stator poles of the DC motor, each provided with an insulation element and a stator winding. 
     (2) Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98 
     A generic electronically commutated DC motor for a liquid pump is known from DE 196 46 617 A1. The connections in the known DC motor are only held in a plug cover without special securing measures and are in direct contact with a circuit board. The same circuit board is directly connected to the winding connections. This structure is not stable and under extreme loads and after a longer running time leads to damage and failures. 
     An object of the present invention is to configure a DC motor, so that it is simple and reliable to install, is designed particularly robust and therefore has a very high lifetime. 
     BRIEF SUMMARY OF THE INVENTION 
     The object is met according to the invention by the commutated DC motor for a liquid pump having a pump housing with a suction connector and a pressure connector for connection to a hydraulic circuit. The DC motor comprises a motor shaft; an essentially disk-shaped pump rotor mounted to the motor shaft to rotate in the pump housing, the rotor having of an impeller with several pump vanes and a permanent magnet; a plurality of axially aligned stator poles; an axial air gap between the pump rotor and the axially aligned wound stator poles; a partition separating a pump space from a dry space, the partition being arranged in the axial gap; a plurality of one piece insulation elements having moldings, the insulation elements being provided on each of the poles; first and second receptacles defined in each of the insulation elements; a stator return mated within each first receptacle; a plurality of stator windings each having first and second winding ends, the stator windings being wound on the poles, the first and second winding ends are mechanically fastened to the moldings; and a first circuit board fastened axially and radially to the second receptacles of the insulation elements. 
     Through the identically designed insulation elements, the number of parts is reduced, so that more reliable assembly is possible. The individual poles permit simple winding of the stator windings and handling of the wound poles and subsequent mounting of a circuit board are simplified by the moldings for fastening of the winding ends. The receptacles ensure simple assembly of a return. The return then assists in alignment of the individual stator poles with their insulation elements and improves the stability of the stator in the installed state. In addition, the robustness of the stator is ensured by radially and axially shape-mated connections between the insulation elements and a circuit board. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       A practical example of the invention is explained below further below with reference to the drawing. In the drawing; 
         FIG. 1  shows a three-dimensional view of a pump housing, 
         FIG. 2  shows the pump housing from  FIG. 1  with an assembled pump rotor, 
         FIG. 3  shows the arrangement from  FIG. 2  with a mounted partition, 
         FIG. 4  shows the arrangement of  FIG. 3  with mounted wound stator poles, 
         FIG. 5  shows the arrangement from  FIG. 4  with a mounted stator return, 
         FIG. 6  shows the arrangement from  FIG. 5  with the mounted contact support, 
         FIG. 7  shows the arrangement from  FIG. 6  with a mounted circuit board, 
         FIG. 8  shows the arrangement from  FIG. 7  with a mounted heat-conducting element, 
         FIG. 9  shows the arrangement from  FIG. 8  with an equipped circuit board, 
         FIG. 10  shows the arrangement from  FIG. 9  with a mounted motor housing, 
         FIG. 11  shows a view of the partition from an opposite perspective, 
         FIG. 12  shows a view of the stator poles from the same perspective, 
         FIGS. 13   a ,  13   b  show views of the heat-conducting element, 
         FIGS. 14   a ,  14   b  show views of the circuit board, 
         FIGS. 15   a ,  15   b  show views of the contact support, 
         FIG. 16  shows a view of a stator pole, 
         FIG. 17  shows the stator pole from  FIG. 16  with mounted insulation elements, 
         FIG. 18  shows the arrangement from  FIG. 17  with a winding, 
         FIG. 19  shows the arrangement from  FIG. 18  from another perspective, 
         FIG. 20   a  shows a second variant of the heat conducting element and 
         FIG. 20   b  shows a third variant of the heat-conducting element. 
     
    
    
     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 three-dimensional view of a pump housing  3 , consisting of plastic material with a suction connector  4 , a pressure connector  5  and screw mounting eyes  36 . 
       FIG. 2  shows the pump housing  3  from  FIG. 1  with a pump rotor  6  mounted in a pump space  9 , which is mounted to rotate on a shaft. The pump rotor  6  consists essentially of a permanent magnet  8  in the form of an alternating magnetized permanent magnet ring connected to an impeller  7 . 
       FIG. 3  shows the arrangement from  FIG. 2  with a mounted partition  11  that separates the pump space from a dry space  10 . The partition  11  also has screw mounting eyes  37  corresponding to the screw mounting eyes  36  of the pump housing  3 . The partition  11  has recesses  13  to accommodate stator poles, especially their pole shoes. The partition  11  also in one piece with three fastening bushings  30  provided with internal thread  42 , which extend parallel around a motor shaft  41  from the partition plane. 
       FIG. 4  shows the arrangement from  FIG. 3  with six mounted wound stator poles  14  aligned axially and parallel and uniformly distributed around the motor shaft  41 . The stator poles  14  are each enclosed by an insulation element  15  provided with a stator winding  16 . The windings are mechanically fastened to the insulation element  15  and their ends  17 ,  18  extend parallel to motor shaft  41 . First winding ends  17  end in a first pane, whereas second winding ends  18  are designed longer than the first winding ends  17  and end in a second plane. The insulation elements  15  are in one piece with receptacles  21   a ,  21   b  that extend pin-like axially and parallel from the side facing away from the pump. The further description of the stator poles  14  occurs relative to  FIGS. 16 to 19 . 
       FIG. 5  shows the arrangement of  FIG. 4  with a mounted stator return  20 , which consists of a laminated core of several identically designed return sheets. This stator return  20  has fastening devices  29 , consisting of three radial protrusions with disk-like punch-outs that are covered with the inside thread  42  of the fastening bushings  30 . Protrusions are provided on two fastening bushings  30 , in addition to internal thread  42 , which are dimensioned differently and are supposed to prevent incorrect assembly of the stator return  20 . Each pole has a mounting pin  19 , which engages in a correspondingly designed recess of the stator return  20 . The stator return  20  is designed ring-like and runs within the circle described by the receptacles  21   a  and  21   b . The stator return  20  is secured against loosening with the stator poles  14  by a deformation process, like caulking. 
       FIG. 6  shows the arrangement from  FIG. 5  with a mounted contact support  22 , consisting of plastic material. The contact support  22  is in one piece with contact receptacles  43 , mounting pins  23 , openings for the receptacles  21   a  and  21   b  of the insulation elements, openings for the winding end  17  with recesses  45  in the area of the fastening bushiness  30 , with a central recess  47  and centering pins  44   a ,  44   b . The mounting pins  23  are designed hollow and accommodate the second winding ends  18 , which, in the assembled state of the contact support, protrude significantly from the hollow mounting pins  23 . The contact supports are shaped so that U-shaped bent contacts can be sealed in them. Part of the U-shaped connection contacts  26  and, on one side, on a first side directed toward the motor shaft, and on the other side in a plug plane, and another part of the U-shaped connection contacts  26  and, on the one side, on a second side facing away from the motor shaft, and on the other side in the plug plane. 
       FIG. 7  shows the arrangement in  FIG. 6  with a mounted circuit board  24 , which is essentially formed with the same passages and recesses as the contact support  22 . In particular, the circuit board  24  has recesses  46  in the area of the fastening bushings  30 , central recess  48  and different openings for the receptacles  21   a ,  21   b  of the insulation elements, for the hollow mounting pins  23  of the contact support and for contact openings for electrical and mechanical connection of the first shorter winding end  17  to the circuit board, especially with soldering eyes that are partially connected to each other via conductor tracks  27 . An opening for the contact receptacles  43  and the centering pins  44   a  is also present. The receptacles  21   a  and  21   b  are shaped according to a heat deformation process, so that the circuit board  24  and the contact support  22  are firmly connected to the six insulation elements in shape-mated fashion, the receptacles  21   a ,  21   b  being deformed in the fashion of rivet heads. 
       FIG. 8  shows the arrangement of  FIG. 7  with a mounted heat-conducting element  25 . The heat-conducting element  25  consists of aluminum and is provided with recesses for hollow mounting pins  23 , centering pins  44   a  and the contact receptacles  43 . The heat-conducting element  25  is also in one piece with spacers  31   a , which engage in recesses  45  of the contact support  22  and recesses  46  of circuit board  24  and extend up to the return  20 . On the side of the heat-conducting element opposite the spacers  31   a , additional spacers  31   b  are provided, which serve to accommodate an additional circuit board. The heat conducting element consists of a first essentially disk-like area and a second essentially hollow cylindrical area, which is centrally connected to the disk-like area and extends over the central recess  48  of the circuit board  24  and the central recess  47  of contact support and a central recess of the stator return up to the partition  11 . 
       FIG. 9  shows the arrangement from  FIG. 8  with an equipped circuit board  28 . The circuit board  28  has contact openings for passage of the winding ends  18 , which are electrically and mechanically connected at soldering eyes to circuit board  28 . This circuit board  28  also has an opening for the contact receptacles  43 . The circuit board  28  lies axially against the spacers  31   b  and radially against the centering pins  44   a ,  44   b  and is screwed to the fastening bushings  30  with screws  49 , so that they also fasten heat conducting element  25  and the stator return, in addition to the circuit board  28 . 
       FIG. 10  shows the arrangement from  FIG. 9  with mounted motor housing  50 , which is in one piece with a plug housing  51 , into which a plug  52  is inserted. The motor housing is also in one piece with screw mounting eyes  38 , in which these agree with the screw mounting eyes  37  of partition  11  and the screw mounting eyes  36  of the pump housing. 
       FIG. 11  shows a view from the opposite perspective of the partition  11  with the motor housing connected to it. The partition  11  and the motor housing delimit the dry space, in which the stator of the DC motor is situated. The partition  11  is in one piece with a bearing mount  53  to accommodate an axial bearing to support the pump rotor. 
       FIG. 12  shows a view from the same perspective of the stator poles  14 , with the insulation elements  15 , windings  16  and the hollow cylindrical area of the heat-conducting element  25 . 
       FIGS. 13   a ,  13   b  show views of the heating conducting element  25  with an opening  55   a  for the centering pins  44   a , three openings  56   a  for the mounting pins  23  of the contact support, a plug recess  33 , spacers  31   a  and  31   b  and a hollow cylindrical area  54  arranged centrally on the heat conducting element. 
     In  FIG. 13   b , large recesses  57  and small recesses  58  are also provided for the soldering sites and rivet heads. 
       FIGS. 14   a ,  14   b  show views of the circuit board  24  with conductor tracks  27 , openings  59   a  for internal mounting of the insulation element, openings  59   b  for outer mounting of the insulation element, central recess  48 , opening  55   b  for the centering pins  44   a , openings  56   b  for the mounting pins  23  of the contact support, recesses  46  for the spacers of the heat conducting element, a plug recess  34  and additional openings for the winding ends. 
       FIGS. 15   a ,  15   b  show views of the contact support  22  with centering pins  44   a ,  44   b , the hollow mounting pins  23 , the contact receptacles  43  that are in one piece with the contact support, recesses  45  for the spacer of the heating conducting element, the central recess for accommodating the cylindrical part of the heat conducting element, openings  60   a  for the internal receptacles of the insulation elements, openings  60   b  for the external receptacles of the insulation elements and openings for the winding wire ends. Inner centering devices  61   a , outer centering devices  61   b  for mounting on the stator return and joining aids  62 , designed essentially conical, in order to be able to join the winding ends more simply during assembly of the contact support, are also shown in  FIG. 15   b.    
       FIG. 16  shows a view of a stator pole  14 , comprising a mounting hole  19  for connection to the stator return and a pole shoe  63 , having a roughly circular segment-like cross-sectional surface. The stator pole  14  in the present practical example consists of a magnetically conducting material pressed and sintered from the powder form. 
       FIG. 17  show the stator pole from  FIG. 16  with the mounted insulation element  15 , with the contact flange  67 , a collar  35 , grooves  64  in the base of the insulation element, which serve to achieve regular arrangement of the winding wires, a wire guide  65 , in order to bring the wire ends in defined fashion against molding  66  after the winding process, and then to wind around the corresponding fastening devices, in which one winding is sufficient. After production of the winding, both winding ends  17  are aligned axial and parallel to the pole axis, and later also the motor axis. The insulation element also has receptacles  39  and  40  to accommodate the stator return  20 . The inner pin-like receptacle  21   a  and the outer pin-like receptacle  21   b  are connected to the receptacles  39  and  40 . Both are aligned axial and parallel. 
       FIG. 18  shows the arrangement from  FIG. 17  wound with a winding  16 . It is readily apparent here how the wire guide is positioned with the winding wire and how the winding wire end is wound around the fastening device. 
       FIG. 19  shows the arrangement from  FIG. 18  from another perspective. It is readily apparent here that the pole has a polygonal cross section  12 . This primarily serves to prevent rotation and finally also for better utilization of space. 
       FIG. 20   a  shows a second variant of the heat-conducting element  25 , in which the disk-like area  69  is provided centrally with a central opening  72  and the hollow cylindrical area  54  is closed by a bottom  70  on its side facing the pump impeller. Through this embodiment, the possibility is obtained of accommodating a capacitor  68  arranged on circuit board  28  in space-saving fashion in a mounting space  74  of the heat-conducting element  25 . 
       FIG. 20   b  shows a third variant of the heat-conducting element  25 , in which the hollow cylindrical area  54  is open on both sides, but a partition  71  is provided in its center area, which separates the dry space from the wet space. In this variant, the partition  11  (not shown here) is also perforated, so that an additional wet space  75  extends to partition  71 . The third variant combines the first two variants of the heat conducting element  25  with each other. In the first place, an installation space for the capacitor  68  is present and, in the second place, part of the hollow cylindrical area  54  can also be used as a cooling channel. On the end of the hollow cylindrical area  54 , there is a receiving space  73  for a bearing. 
     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 disclosed. 
     LIST OF REFERENCE NUMBERS 
     
         
           1  DC motor 
           2  Liquid pump 
           3  Pump housing 
           4  Suction connector 
           5  Pressure connector 
           6  Pump rotor 
           7  Pump impeller 
           8  Permanent magnet 
           9  Pump space 
           10  Dry space 
           11  Partition 
           12  Polygonal cross section 
           13  Recesses 
           14  Stator pole 
           15  Insulation element 
           16  Stator winding 
           17  First winding end 
           18  Second winding end 
           19  Mounting pin 
           20  Stator return 
           21   a  Receptacle 
           21   b  Receptacle 
           22  Contact support 
           23  Hollow mounting pin 
           24  First circuit board 
           25  Heat conducting element 
           26  Connection contact 
           27  Circuit 
           28  Conductor track 
           29  Equipped circuit board 
           30  Fastening device 
           31  Fastening bushing 
           31   a  Spacer 
           31   b  Spacer 
           33  Plug recess 
           34  Plug recess 
           35  Collar 
           36  Screw connection eye 
           37  Screw connection eye 
           38  Screw connection eye 
           39  Receptacle for return 
           40  Receptacle for return 
           41  Motor shaft 
           42  Internal thread 
           43  Contact receptacle 
           44   a  Centering pin 
           44   b  Centering pin 
           45  Recesses in contact support 
           46  Recesses in circuit board 
           47  Central recess in support 
           48  Central recess in circuit board 
           49  Screw 
           50  Motor housing 
           51  Plug housing 
           52  Plug 
           53  Bearing mount 
           54  Hollow cylindrical area 
           55   a  Opening for centering pin 
           55   b  Opening for centering pin 
           56   a  Opening for mounting pin 
           56   b  Opening for mounting pin 
           57  Large recess 
           58  Small recesses 
           59   a  Opening for receptacle inside 
           59   b  Opening for receptacle outside 
           60   a  Opening for receptacle inside 
           60   b  Opening or receptacle outside 
           61   a  Internal centering device 
           61   b  External centering device 
           62  Joining aid 
           63  Pole shoe 
           64  Groove 
           65  Wire guide 
           66  Moldings 
           67  Contact flange 
           68  Capacitor 
           69  Disk-like area 
           70  Bottom 
           71  Partition 
           72  Central opening 
           73  Receiving space for bearing 
           74  Receiving space for capacitor 
           75  Additional wet space