Abstract:
The invention relates to an electric motor having a permanent magnetic rotor supported in a rotatable fashion around a central axis, a wound stator with a cylindrical stator winding, claw poles, perpendicular in reference to the disc-shaped stator plates and arranged around the central axis, and a tubular return ring connected to the stator plates free from play. The object of the invention is to provide an electric motor, in which the stator is composed from as few parts as possible, with its assembly being simple, its construction being robust, and being provided with an optimum effectiveness, allowing a great freedom of design and space used and thus an economical structure. This object is attained according to the invention in the disc-shaped stator plates being in one piece with the claw poles and being calked to the return ring with the disc-shaped stator plates.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     (1) Field of the Invention  
         [0002]     The invention relates to an electric motor with a permanent magnetic rotor supported in a rotatable manner around a central axis, a wound stator with a cylindrical stator winding, claw poles arranged perpendicular in reference to the disc-shaped stator plates and arranged around the central axis and connected to a tubular return ring, connected to the stator plates free of play.  
         [0003]     The most frequently used way to produce claw pole stators consists of bending the claws pre-punched from a disc in the center of said disc. This way the maximum length of the claws in the axial direction is limited to approximately half the interior diameter of the stator. This limits the performance achievable by such motors and, if necessary, several stators have to be arranged in line with other.  
         [0004]     (2) Description of the Related Art  
         [0005]     From US 2002/2180302 A1, a generic electric motor is known. In the electric motor known the stator is composed of four parts. Here, the claw poles are punched from strip-shaped sheet metal and subsequently bent to a ring and the ends are connected to each other. Two of these bent claw pole sheet metals are subsequently assembled together with two additional stator plates. This method is relatively expensive and unreliable. The many seams additionally increase the magnetic resistance and thus reduce the effectiveness of the motor.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     The object of the invention is therefore to provide an electric motor, in which the stator comprises as few parts as possible, its assembly is easy, its structure is robust, and has an optimum effectiveness, with a large design freedom and usability of constructive space and thus an economical structure being possible.  
         [0007]     This object is attained according to the invention in that the disc-shaped stator plates and the claw poles are embodied in one piece and the return ring is calked to the disc-shaped stator plates. This way the magnetic resistance is low and accordingly the effectiveness is high and the assembly is facilitated.  
         [0008]     The return ring should be connected to the stator plates with as little play as possible, in order to yield a low magnetic resistance and thus a high effectiveness. Preferably the calking of the return ring with the stator plates is achieved such that the return ring has slots at several points in its axial edge region and sheet metal bars adjacent to the slot are deformed radially inward. By the deformation the return ring is pulled inwardly onto the disc-shaped stator plates, reducing the magnetic resistance in this area. Further, the sheet metal bars form a form-fitting connection between the return ring and the disc-shaped stator plates, and thus also the claw poles in the axial direction.  
         [0009]     From reasons of production technology V-shaped notches are provided in the disc-shaped stator plates, which are arranged at the radially exterior edge of the stator plates, with the notches converging in the direction of the center of the stator plate.  
         [0010]     Great freedom of design choice and use of construction space is provided. In this way, an economical structure for the stator and thus for the electric motor is possible when the length of the claw poles is distinctly larger in a direction parallel to the axis than half the interior diameter of the stator.  
         [0011]     In order to fix the claw pole and to maintain their distance from each other they shall be connected to each other via an electrically insulating plastic material. Preferably this is designed such that the claw poles are injection-molded with a plastically processed plastic material into the form of an insulating body for the stator winding.  
         [0012]     A further embodiment of this inventive concept is suggested to embody the insulating body with quick connectors with a protrusion being provided for each adjacent winding wires at the insulating body in the axial direction, having an accepting slot for a connection wire and an assembly recess for the contact pin.  
         [0013]     Advantageously, the insulating body is in one piece with the mounting means for a circuit board. The mounting means are here composed from a stop and a latching means. The stop determines the axial position of the circuit board in reference to the insulating body and the latching means ensure a secure fastening to the circuit board in this position, with them representing a form-fitting connection in the radial direction that can only be overcome axially with force. The circuit board is provided with recesses in their diameter adjusted to the latching means. This way the circuit board can easily and simply be fastened to the insulating body, with it being further provided that the contact pin on the one hand has a clamping-cutting geometry and on the other hand is a solder-free compression contact, electrically connected to the circuit board. By this embodiment of the contact pin, during assembly of the circuit board, simultaneously an electric connection can be created between the stator winding and the circuit board. Preferably the contact pins are compressed into it prior to the assembly of the circuit board.  
         [0014]     The invention also comprises a rotary pump driven by an electric motor of the above-described type. When using a rotary pump, it is suggested that the insulating body is embodied in one piece with the separating can, separating the wet chamber from a dry chamber of the rotary pump. This way the insulating body can be omitted as an additional component.  
         [0015]     In a particularly preferred further embodiment for laser light of a wave length or a wavelength range, the separating can, as a part of a second housing part, being welded to a first housing part and the separating can as a part of a second housing part being welded to a motor housing part. The first housing part or the motor housing part comprises a material absorbing the same laser light. By this arrangement it is possible to tightly and in a sealed fashion weld the first housing part with the second housing part and the second housing part with the motor housing part using the laser penetrating welding method.  
         [0016]     The preferred method for producing claw poles has the following steps:—deep-drawing a can made from a magnetically conducting sheet metal,—radially punching out claw poles from the can, deforming the claw poles into an exact form. Here, it is advantageous that a sufficient roundness of the disc-shaped stator plates can be yielded so that a low magnetic resistance can be produced in reference to the return ring.  
         [0017]     An advantageous method for producing claw pole stators includes the following steps:—punching out flat claw poles connected to each other via a continuous sheet metal strip,—roll-bending of the sheet metal strip,—welding the ends of the sheet metal strips together,—injection-molding the claw poles using a plastic material in the form of an insulating material body,—radially punching out bars connecting the sheet metal strips to each other,—winding the insulating body,—assembling the return ring, and calking it to the roll-bent stator part. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     In the following, an exemplary embodiment is explained in greater detail using the drawing. It shows:  
         [0019]      FIG. 1 a  circular disc-shaped stator plate with claw poles,  
         [0020]      FIG. 2  two stator plates separated from each other,  
         [0021]      FIG. 3  two stator plate-sections connected to each other by sheet metal bars,  
         [0022]      FIG. 4 a  side view (from the right) of a tubular return ring,  
         [0023]      FIG. 5 a  front view of the return ring,  
         [0024]      FIG. 6 a  spatial representation of the return ring,  
         [0025]      FIG. 7 a  side view (from the left) of the return ring,  
         [0026]      FIG. 8 a  stator prior to a deformation process,  
         [0027]      FIG. 9 a  stator after the deformation process,  
         [0028]      FIG. 10  the stator after the deformation process from a different perspective, and  
         [0029]      FIG. 11 a  cross-section through a rotary pump according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]     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.  
         [0031]      FIG. 1  shows a circular disc-shaped stator plate  420  with four claw poles  42 , bent at a right angle away from the stator plates  420 , with the stator plates  420  having ends  421  welded to each other, overlapping. The circular disc  420  is provided at its perimeter with V-shaped recesses  422 , which are arranged evenly distributed over the perimeter. The claw poles are shaped trapezoidal for reducing a detent torque, narrowing towards their free end.  
         [0032]     In a first exemplary embodiment  FIG. 2  shows two circular disc-shaped stator plates  420  with their claw poles  42  in an opposite position, with each claw pole  42  of the first stator plate  420  following a claw pole of the second stator plate  420 . The two stator plates  420  are shown in their correct position; however, they are not contacting each other. In the assembled state the sheet metals are fastened by an insulating body. The insulating body, made from a material that can be processed by injection molding, is here molded around the sheet metal, with additional connecting and fasting means being formed.  
         [0033]      FIG. 3  shows a second embodiment of the invention, in which the stator plates  420  with the claw poles  42  are punched out of a single sheet metal strip, with the claw poles  42  being connected to each other via sheet metal bars  423 . The sheet metal bars may remain in the stator in the final assembly state, if they are embodied sufficiently thin; however, they reduce the effectiveness of the motor. Here, it would be more advantageous to remove the bars. This results in a higher production expense. The geometry of the stator, with the exception of the sheet metal bars  423 , is equivalent to the arrangement of  FIG. 2 . Two claw poles  42  are not connected to each other via sheet metal bars, but they form the ends of the sheet metal strip mentioned. The circular disc-shaped stator plates  420  are welded to each other at their ends  421  similar to  FIGS. 1 and 2 . The welding can occur in a device in which the interior diameter of the claw pole ring is calibrated.  
         [0034]      FIG. 4  shows a right side view of a tubular return ring  43 , punched out of a sheet metal strip and rolled. The two ends of the sheet metal strip are connected to each other at a seam  437 .  
         [0035]     The seam is formed in the shape of form-fitting and button-shaped matching connection means  438 . The return ring (here seen at its rear) is provided at the perimeter of the return and has slots  431  arranged in its edge region, narrowing towards the center and being provided at their ends with radii. As clearly discernible in  FIGS. 6 and 7 , two slots  431  are provided arranged in the same circumferential area but at opposite brims  435 ,  436 . The two slots  431  are each connected to each other by a connecting slot  432 , each beginning at the center of the slots  431 . The slots  431  and  432  together form an H-shape. The slots  431  each separate a bar  430  from the return body. Further,  FIGS. 4 and 6  show open slots  433 , open towards a recess  434 . Sheet metal tongues  439  form by the slots  433 , serving for the axial fastening of the stator plates  420  by a radial bending (inwardly). The sheet metal bars  430  serve both for the axial fastening of the stator plates  420  as well as the reduction of the diameter of the return. By a radial deformation of the sheet metal bars  430  the connection slot  432  narrows, if necessary until the two edge regions of the connection slot  432  contact.  
         [0036]     In  FIG. 5 a  front view of the return ring  43  is shown with a recess  434 .  FIG. 6  shows a spatial view of the return ring  43  and  FIG. 7 a  side view (from the left).  
         [0037]     In  FIG. 8  the return ring  43  is on a wound stator structure made from stator plates  420  (hidden) with claw poles  42 , insulating body  46 , injection molded around the stator plates, with the insulating body being provided with protrusions  466  having a receiving slot  461 , in which a wire end of a stator winding is inserted and contacts a contact pin  62 . In  FIG. 8 a  stator  40  is shown prior to the deformation process, having slots  431 , the connection slot  432 , the sheet metal bars  430 , and the sheet metal tongues  439 . A distinct distance between the two borders of the connection slot  432  is discernible in the circumferential direction of the return ring  43 .  
         [0038]      FIG. 9  shows the stator after the deformation process, with the sheet metal bars  430  being deformed radially inwardly, thus the tensile forces in the sheet metal bars  430  ensure a narrowing of the connection slot  432 . Depending on the tolerance ratios of the stator structure, onto which the return is mounted, the connection slot  432  can be closed entirely or may still show a slight gap. Sheet metal tongues  439  are also bent inwardly and together with the deformed sheet metal bridges  430  form an axial fixture for the stator structure.  
         [0039]      FIG. 10  also shows the stator after the deformation process, with sheet metal tongues  439  also being discernible from a different perspective, again bent inwardly in the deformation process. The sheet metal tongues  439  form, together with the inwardly deformed sheet metal bars  30 , a reliable axial fastening of the stator structure. The slots  431  and  433  are expanded during the deformation process.  
         [0040]      FIG. 11  shows a cross-section through a rotary pump  100  according to the invention, having a pump housing  102 , comprising a first housing part  103  and a second housing part  104  adjacent thereto. A housing part  44  limits a dry chamber filled by a stator ( 40 ) of an electronically commuted direct-current motor and its control electronics. The motor housing part  44  abuts to the second housing part  102 . The first and the second housing part  103 ,  104  limit a wet chamber  101  of the rotary pump. The second housing part  104  is formed in one piece with a separating can  116 , which the wet chamber  101  from a dry chamber  99 .  
         [0041]     The wet chamber  101  includes an axis  49  implemented in a fixed manner between an axial recess  48  at the side of the separating can and an axial recess  47  at the side of the intake-socket. A beading at the end of the axle prevents a distortion of the axle  49  during the pump operation. A fixed bearing  54  is supported in a rotatable fashion on the axle  49 , which is impressed into a hollow shaft  51  of the rotor  50 . The shaft  51  is made in one piece with a pump wheel  59 , comprising several approximately helically shaped blades  591  for transporting liquids. The faces of the fixed bearing  54  may be axially supported against the axial recess  48  at the side of the separating can and against the axial recess  47  at the side of the intake-socket, with spacers positioned intermediately. A hollow-cylindrical ferrite magnet  52  is adhered onto the hollow shaft  51 , with an elastic adhesive being used inserted into four or five of the grooves  511  formed parallel to the axle in the hollow shaft.  
         [0042]     The dry chamber  99  receives the stator  40  of the electronically commuting direct current motor  10 , embodied in the form of a hollow-cylindrical stator winding  41 , with their magnetic field being guided during operation via claw poles in an alternating fashion at the perimeter of the separating can  116  and interacting with the hollow cylindrical permanent magnets  52  in the wet chambers  101 . The magnetic circuit is closed by a return ring  43 , connected to the claw poles  42 . The claw poles  42  are provided with an insulating body  46  by way of injection molding, connecting the claw poles  42  to each other mechanically but not magnetically. In the present example the stator  40  has four pairs of poles. The insulating body  46  is geometrically shaped such that the winding wires of the stator winding  41  can be connected with contact pins  62  provided with quick connectors and these quick connectors can be fastened mechanically in the insulating body  46 .  
         [0043]     At their end opposite the quick connectors  63  the contact pins  62  are formed as combination contacts and are impressed into a circuit board  61  and thus contact it. Here, the contact pins  62  include one or two compression zones that can be deformed. The circuit board  61  includes a Hall sensor  71 , an integrated circuit  70  IC for switching the stator coil and a PTC for the winding protection and plug pins  64  for the power supply. The motor housing part  44  includes a plug housing  65 , in which the plug pins  64  are arranged. Electronic parts with a high heat loss are cooled via heat conducting foils  67  towards the wet chamber  101 .  
         [0044]     Conductors serving to contact the parts to be cooled are sized such that conduits  66  as wide as possible are provided on the circuit board  61  for an easier heat removal. In order to utilize the circuit board  61  as well as possible and to achieve an optimum heat removal the different conductors  66  are embodied in different widths, depending on the amount of heat developing in the part the connectors contact. In the shaft  51  a longitudinal groove is formed as a cooling channel between a bottom  117  of the separating can  116  and the pump rotor  59 , forcing a continuous circulation of the transportation medium even inside the separating can  116 . The circuit board is arranged between a face  45  of the motor housing  44  and the bottom  117  of the separating can  116  and is held to the bottom  117  in a heat conducting contact by the head conducting foil  67 .  
         [0045]     The first housing part  103  has a first flange  130  and a first ring  131  adjacent thereto. The second housing part  104  has a second flange  140  and a second ring  141  adjacent thereto. The motor housing part is provided with a third ring  441 . The second flange  140  and the second ring  141  together form a T-shape in the cross-section. Four sealing areas  133 ,  144 ,  145 , and  444  are provided. The first sealing area is located on the radially exterior side of the first ring  131  at the first housing part  103 . Opposite to the radially inward located side of the second ring  141  and the second housing part  104  the second sealing area  144  is located. Also the third sealing area  145  is located at the radially inward side of the second ring  141  and the second housing part  104 . The fourth sealing area  444  is located opposite thereto on the radially exterior of the third ring  441  and the motor housing part  44 . The second housing part  104  comprises a material permeable by laser light with a wavelength or a wavelength range. The first housing part  103  and the motor housing part  44  comprises a material absorbing the same laser light. This way, a laser beam can be guided to the seam without heating the transparent material. Here, the beam impinges the material absorbing the light and converting it into heat, thus melting the plastic and creating an intimate connection with the neighboring material.  
         [0046]     Due to the fact that the sealing areas to be welded together are located at close proximity to each other it is easily possible to create the two seams in one device and in one processing step. The welding device may be provided with two lasers, with each laser creating one welding seam, or it may be provided with a single laser, its output beam being split into two radiation beams by a beam splitter, each of which creating one welding seam. In the example shown the laser beams are radially deflected to the pump housing.  
         [0047]     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 CHARACTERS  
       [0000]    
       
           10  electric motor  
           20  air gap  
           40  stator  
           41  stator winding  
           42  claw pole  
           420  disc-shaped stator plates  
           421  end  
           422  recess  
           423  bar  
           424  air gap  
           43  return ring  
           430  sheet metal bar  
           431  slot  
           432  connecting slot  
           433  open slot  
           434  free space  
           435  first brim  
           436  second brim  
           437  seam  
           438  connecting means  
           439  sheet metal tongue  
           44  motor housing  
           45  face (of the motor housing)  
           46  insulating body  
           461  accepting slot  
           462  assembly recess  
           463  fastening means  
           464  stop  
           465  latching means  
           466  protrusion  
           467  fastening (for connector pins)  
           47  axial recess at the side of the injection-socket  
           48  axial recess at the side of the separating can  
           49  axis  
           50  rotor  
           51  shaft  
           511  notch  
           512  disc  
           52  hollow-cylindrical permanent magnet  
           521  operating magnetization  
           522  sensor track—magnetization  
           523  face (of the permanent magnet)  
           524  safety gap  
           53  elastic connection means  
           531  first area (wide)  
           532  second area (narrow)  
           54  fixed bearing  
           58  longitudinal groove (for secondary liquid circuit)  
           59  pump rotor  
           591  blade  
           60  electronics  
           61  circuit board  
           611  recesses  
           62  contact pin  
           63  quick connector  
           64  contact pin  
           641  formed protrusions  
           65  plug housing  
           66  conductor  
           67  heat conducting foil  
           70  integrated circuit (IC)  
           71  Hall sensor  
           99  dry chamber  
           100  rotary pump  
           101  wet chamber  
           102  pump housing  
           103  first housing part  
           104  second housing part  
           105  injection socket  
           106  pressure socket  
           109  pump chamber  
           111  round contour  
           112  mandrel  
           113  transfer area  
           114  perimeter wall  
           115  sharp edge  
           116  separating can  
           117  bottom  
           118  rotor chamber  
           119  indentation  
           120  helical interior contour  
           121  recess  
           122  pump fastening means  
           123  rounding  
           130  first flange  
           131  first ring  
           133  first sealing area  
           140  second flange  
           141  second ring  
           144  second sealing area  
           145  third sealing area  
           150  swallow-tail contour  
           151  complementary contour  
           152  V-shaped recess  
           441  third ring  
           444  fourth sealing area