Abstract:
The invention relates to an electric motor, in particular for a pump in a motor vehicle. The electric motor has a housing, a stator and an armature. The electric motor also has a control unit which is preferably formed on a printed circuit board, wherein the printed circuit board is connected to the housing and/or to the stator via electrical connecting lines which are in particular in the form of wires and are solid. According to the invention, in the electric motor, the connecting points which each connect one connecting line to the printed circuit board are arranged together on one printed circuit board surface of the printed circuit board, on a contact area which is smaller than the printed circuit board area, such that mechanical deformation effects to the printed circuit board caused by temperature fluctuations and/or vibration at the connecting points are reduced to a minimum, or at least in comparison to an arrangement which is distributed in particular uniformly over the printed circuit board surface.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to an electric motor, in particular for a pump of a motor vehicle. The electric motor has a housing, a stator and an armature. The electric motor also has a control unit which is preferably formed on a printed circuit board, with the printed circuit board being connected to the housing and/or to the stator via, in particular, wire-like, preferably solid, electrical connecting lines. 
         [0002]    DE 10 2007 031 2461 discloses an electronic control apparatus for a power steering system, with the power steering system being designed to produce an assistance force for a steering system of a vehicle by means of a rotation force of an electric motor. The controller has a housing which accommodates a printed circuit board and press-in pins, with the printed circuit board being connected to the press-in pins. 
       SUMMARY OF THE INVENTION 
       [0003]    According to the invention, the connecting points in the case of the electric motor of the type cited in the introductory part, said connecting points in each case connecting a connecting line to the printed circuit board, are arranged together on a printed circuit board surface of the printed circuit board, in a contact area which is smaller than the printed circuit board surface, in such a way that mechanical deformation effects, which are caused by fluctuations in temperature and/or vibrations, on the printed circuit board at the connecting points are reduced to a minimum or at least in comparison to an arrangement which is distributed, in particular uniformly, over the printed circuit board surface. 
         [0004]    This arrangement of the electrical connecting lines has the advantageous effect that connecting points, which connect the printed circuit board to the electrical connecting lines, advantageously cannot be changed, destroyed or interrupted by, in particular, thermal expansions or mechanical vibrations which cause a relative movement between the printed circuit board and the housing and/or the stator. The connecting points preferably form a group in the contact area; the contact area is further preferably circular. 
         [0005]    In a preferred embodiment of the electric motor, the contact area is less than half the size of the printed circuit board surface, further preferably a third of the size of the printed circuit board surface, particularly preferably a quarter or a fifth of the size of the printed circuit board surface. This has the advantageous result that, in comparison to a contact area which corresponds to the printed circuit board surface, relative movements, which are caused by thermal expansions of the printed circuit board and/or of the connecting lines, are reduced to a minimum or at least in comparison to an arrangement which is distributed, in particular uniformly, over the printed circuit board surface. 
         [0006]    In an advantageous embodiment of the electric motor, at least some of the electrical connecting lines have at least one loop or at least one meander, said loop and meander in each case being designed to absorb a force which acts in the longitudinal direction of the connecting line, and preferably to at least partially store said force, in particular with a spring. As a result, thermal expansions of the printed circuit board can advantageously be at least reduced or not act on the electrical connecting point. The loop is preferably formed by a half-wave of a sinusoidal or square wave. In a preferred embodiment of the electric motor, the printed circuit board is mounted in a floating manner in such a way that the printed circuit board is supported at least predominantly or exclusively by the connecting lines. These embodiments have the advantageous effect that mechanical forces and/or forces which are caused by thermal expansion can be transmitted to the connecting points only at least partially or cannot be transmitted to the connecting points at all. 
         [0007]    The contact area is preferably arranged in the center of the printed circuit board surface. The floating mounting arrangement can be formed, for example, by the printed circuit board being connected to a housing of the electric motor by means of at least one coupling element, with the coupling element preferably having a lower modulus of elasticity than the printed circuit board and/or the housing. The coupling elements can be formed, for example, by an elastomer, for example silicone rubber or polyurethane. The printed circuit board is then advantageously mounted in a floating manner in such a way that the printed circuit board is supported at least predominantly by the connecting lines. 
         [0008]    In a preferred embodiment, the connection between the printed circuit board and the connecting line is pressed. The pressed connection has the advantageous effect that both a mechanical connection and an electrical connection are established by the pressed arrangement between the connecting line and the printed circuit board. 
         [0009]    In an advantageous embodiment, the connection between the printed circuit board and the connecting line is soldered. The soldered connection advantageously establishes an electrical connection between the printed circuit board and the connecting line. In this embodiment of the soldered connection, a mechanical connection between the printed circuit board and the connecting line is formed at least by the soldered point. In the case of the soldered connection, the printed circuit board is preferably connected to the housing and/or to the stator of the electric motor in such a way that the printed circuit board is supported at least predominantly by the connection between the printed circuit board and the housing. As a result, a mechanical loading on the soldered point is advantageously low. 
         [0010]    In a preferred embodiment of the electric motor, the printed circuit board is substantially or exactly circular and is arranged transverse to a motor shaft axis. The motor shaft axis preferably runs through the contact area, in particular a center of gravity of the contact area. The contact area is advantageously arranged in the center of the printed circuit board surface. 
         [0011]    The arrangement of the contact area in such a way that the motor shaft axis runs through the contact area has the advantageous effect that oscillations of the housing of the electric motor, which are caused by rotation of the motor shaft, in particular with a motor armature, advantageously act only slightly on the connecting points or do not act on the connecting points. 
         [0012]    In a preferred embodiment of the electric motor, the connecting points of connecting lines of a component are arranged on a radial, with the radial extending from a point of the contact area to an edge of the printed circuit board. The point of the contact area is preferably a center of gravity of the contact area, a center of gravity of the surface of the printed circuit board, a center point of the contact area or a point through which the motor shaft axis runs. The above-described arrangement has the advantageous effect that connecting lines, in particular connections of a component, which connect the component to the printed circuit board, are preferably slightly mechanically loaded or are not mechanically loaded in the event of thermal expansions and/or mechanical deformations of the printed circuit board. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The invention will now be described below with reference to figures and further exemplary embodiments. 
           [0014]      FIG. 1  shows an exemplary embodiment of a pump for a motor vehicle having an electric motor. In the pump, a printed circuit board is connected to electrical contacts of the electric motor in such a way that mechanical deformation effects, which are caused by fluctuations in temperature, on the printed circuit board at the connecting points are reduced in comparison to a uniform distribution over the printed circuit board surface; 
           [0015]      FIG. 2  shows an exemplary embodiment of connecting lines which has looped and meandering longitudinal sections; 
           [0016]      FIG. 3  shows an exemplary embodiment of a Hall sensor which has connecting lines which are designed to electrically connect the Hall sensor and which have at least one loop in each longitudinal section; 
           [0017]      FIG. 4  shows an exemplary embodiment of an electric motor, in which contacts of connecting lines are connected to a printed circuit board, with the printed circuit board being connected to a housing of the electric motor by means of a connecting web; 
           [0018]      FIG. 5  shows a plan view of an exemplary embodiment of the electric motor shown in  FIG. 4  without the printed circuit board; 
           [0019]      FIG. 6  shows an electric motor, in which the printed circuit board is supported in a floating manner by connecting lines which are in each case connected to a housing and/or stator of the electric motor and are in each case in the form of press-in pins. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  shows an exemplary embodiment of a pump  1 . The pump  1  has a housing  3 , with the housing  3  surrounding an electric motor. The electric motor has a stator comprising at least one stator coil  5 . The electric motor also has an armature  7  which is permanently magnetic in this exemplary embodiment. The armature  7  is connected to an impeller  10  which is integrally formed on the armature  7  in this exemplary embodiment. The armature  7 , which forms a rotor of the electric motor in this exemplary embodiment, is mounted so as to rotate about a motor shaft axis  20  by means of a bearing  21  and a bearing  22 . 
         [0021]    The pump  1  also has a pump housing  24  which is accommodated by the housing  3 . The pump  1 , in particular the electric motor of the pump  1 , also has a printed circuit board  14 . The printed circuit board  14  is accommodated and arranged by the housing  3  in such a way that a printed circuit board plane of the printed circuit board  14  runs transverse to the motor shaft axis  20 . 
         [0022]    The printed circuit board  14  has a plurality of conductor tracks—not illustrated in this figure—which connect contacts of components, in particular electronic components, to one another, with the components being arranged on the printed circuit board  14 . A module  16  which is connected to the printed circuit board  14  is illustrated. The module  16  is, for example, a SMD module (SMD=Surface−Mounted Device). 
         [0023]    The electric motor also has a Hall sensor  18 . The Hall sensor  18  is arranged in such a way that a rotational frequency of the armature  7  can be detected by the Hall sensor  18 . The Hall sensor  18  is designed to generate an output signal as a function of the rotation of the armature  7 , said output signal representing the rotational frequency. The Hall sensor  18  has three connecting lines for making electrical contact with the Hall sensor  18 , specifically a connecting line  30 , a connecting line  31  and a connecting line  32 . The connecting lines  30 ,  31  and  32  are in each case arranged in a region  15  with the printed circuit board  14 . The region  15  forms a contact area which is smaller than a printed circuit board surface of the printed circuit board  14 . A diameter  17  of the printed circuit board  14  is also illustrated. 
         [0024]    The at least one stator coil  5  is connected to the printed circuit board  14  in the region  15  by means of connecting lines  33 ,  34  and  35 . 
         [0025]    The pump  1  also has an electrical connection, with the electrical connection comprising three connecting lines, specifically a connecting line  36 , a connecting line  37  and a connecting line  38 . The connecting lines  36 ,  37  and  38  are in each case in the form of contact pins in the electrical connection, and therefore a plug can make contact with the connecting lines  36 ,  37  and  38  at least in sections in the region of one end. The connecting line  36  is connected to the printed circuit board  14  in the region  15  in the region of another end  60 . A looped region  50 , which is described in greater detail in  FIG. 2 , is also identified. The connecting line  37  is connected to the printed circuit board  14  by means of another end  62  in the region  15 . The connecting line  38  is connected to the printed circuit board  14  in the region of another end  64  in the region  15 . The connecting lines  30 ,  31 ,  32 ,  33 ,  34 ,  35 ,  36 ,  37  and  38  can in each case be connected to the printed circuit board  14  both by means of a pressed connection and a soldered connection. 
         [0026]    The housing  3  of the pump  1  also has a connection flange  12  which is designed to connect the pump  1 —for example to a cooling system of an internal combustion engine—such that it carries fluid. The housing  3  also has a holding apparatus  23  which is integrally formed on said housing and is designed to accommodate and firmly hold the Hall sensor  18 . 
         [0027]    The connecting line  36  has, in one section, a loop—illustrated in greater detail in FIG.  2 —which is designed to absorb forces which act in the longitudinal direction of the connecting line  36 . 
         [0028]    FIG.  2 —schematically—shows an exemplary embodiment of the connecting lines  36 ,  37  and  38  which have already been illustrated in  FIG. 1 . The connecting line  36  has a loop  50  in the region of a longitudinal section, said loop being semicircular in this exemplary embodiment. The loop  50  merges with a further section of the connecting line  36 , with the connecting line  36  being designed for mechanical and/or electrical connection to the printed circuit board  14 , which has already been illustrated in  FIG. 1 , in the region of one end  60 . The connecting line  36  has a start section and an end section, said sections in each case being angled—so as to point in the same direction. 
         [0029]    The connecting line  37  has a meandering section  52 . The meandering section  52  resembles a sinusoidal wave in this exemplary embodiment. The meandering section  52  of the connecting line  37  is designed to store forces—which are caused, for example, by thermal expansion—which act in the longitudinal direction of the connecting line  37 , and thus to relieve the mechanical load on the connecting points of the connecting line  37 . The connecting line  37  has two ends which are in each case angled so as to point in the same direction. The meandering section  52  turns into an end section  62  of the connecting line  37  which is designed for connection to a printed circuit board, for example the printed circuit board  14  which is illustrated in  FIG. 1 . The connecting line  38  has two ends, with one end  64  being designed for connection to a printed circuit board, and with the ends in each case being angled so as to point in the same direction. A longitudinal section which forms a loop  54  extends between the ends of the connecting line  38 . The loop  54  is designed to absorb forces which act in the longitudinal direction of the connecting line  38 , and thus to relieve the mechanical load at least on the end  64  which is designed for connection to a printed circuit board. 
         [0030]      FIG. 3  schematically shows an exemplary embodiment of a Hall sensor  18 . The Hall sensor  18  has three electrical connections, specifically an electrical connection  30 , an electrical connection  31  and an electrical connection  32 . The electrical connections  30 ,  31  and  32  are in each case in the form of connection legs. The connections  30 ,  31  and  32  in each case have a longitudinal section  58  which is in each case formed by a loop  56 . The loop  56  is identified, by way of example, on the connection  30 . The loop  56  has a half-wave shape in this exemplary embodiment. The loop  56  is designed to store a deformation which acts in the longitudinal direction of the connection  30 , and thus to relieve the mechanical load on a connecting point, for example a soldered point, which connects the connection  30  to a printed circuit board. 
         [0031]      FIG. 4  shows an exemplary embodiment of an electric motor in which connections of electrical connecting lines, which are, in particular mechanically, connected to a housing of the electric motor, are connected to a printed circuit board  13  by means of a soldered connection on a contact area  42  and combined to form a group in such a way that mechanical forces, which are caused by fluctuations in temperature in particular, on the connections are minimal. The plan view illustrated in  FIG. 4  shows the connections of the connecting lines  30 ,  31  and  32  of the Hall sensor  18  which is illustrated in  FIG. 1 , said connections in each case projecting out of the printed circuit board  13  and being routed through said printed circuit board. 
         [0032]    Connections of the connecting lines  33 ,  34 ,  35 ,  36 ,  37  and  38  which have already been illustrated in  FIG. 1 , are in each case routed through the printed circuit board  13  and project out of the printed circuit board  13  are also illustrated. The contact area  42  is, for example, circular. 
         [0033]    The printed circuit board  13  is mechanically connected to the housing of the electric motor by means of a bayonet pin  40 . 
         [0034]      FIG. 5  shows a plan view of the electric motor, of which a section has already been illustrated in  FIG. 4 . The electric motor has a housing  3 , with a connection  44  for electrical connection of the electric motor—for example to a control unit or to a supply voltage source—being integrally formed on the housing  3 . The plan view which is illustrated in  FIG. 5  shows the electric motor without the printed circuit board  13  which is illustrated in  FIG. 4 . The bayonet pin  40 , the connecting lines  30 ,  31 ,  32 ,  33 ,  34 ,  35 ,  36 ,  37  and  38 , which are in each case mechanically connected to the housing  3  of the electric motor, can be seen. 
         [0035]      FIG. 6  shows an exemplary embodiment of an electric motor in which—as in FIG.  1 —a printed circuit board  14  is supported by electrical connecting lines, with the electrical connecting lines being connected to a housing of the electric motor, in this exemplary embodiment to a stator  75 . In this exemplary embodiment, the printed circuit board surface of the printed circuit board  14  has, at least in sections or predominantly, a circular circumference. The printed circuit board  14  has a contact area  72  which is arranged in the center of the printed circuit board  14 , with the printed circuit board  14  being supported in the region of the contact area  72  by means of the electrical connecting lines  76 . 
         [0036]    The electric motor also has guide webs which are in each case mechanically connected to the stator  75  and which engage in corresponding cutouts in the printed circuit board  14 . The printed circuit board  14  is held by the connections  76  in such a way that the printed circuit board  14  is mounted in a floating manner and does not touch the guide webs. A guide web  70  is identified by way of example. 
         [0037]    The electric motor also has electrical connections for electrically connecting the electric motor to a supply voltage source or a control unit. In this exemplary embodiment, the electric motor has three electrical connections, of which the connection  74  is identified by way of example. In this exemplary embodiment, the electrical connections are in each case in the form of split contacts, it being possible for provision to be made for connecting lines for connecting the electric motor—for example the connecting lines  36 ,  37  and  38  in FIG.  1 —to be connected to the split contacts. To this end, the connecting lines  36 ,  37  and  38  can in each case be connected to a housing cover, it being possible for one end of the connecting lines  36 ,  37  and  38  to engage in a tongs-like connection  74 . A further section of the connecting lines, which are in each case routed through the printed circuit board  14  by way of an end section and—like the connecting line  46 —project out of the printed circuit board  14  and make both mechanical and electrical contact with said printed circuit board, runs between the tongs-like connection  74  and the printed circuit board  14 . The connecting lines  36 ,  37  and  38  can in each case be in the form of press-in pins.