Abstract:
An electric machine ( 1 ), particularly used as an electric motor, has a rotor ( 2 ) comprising a plurality of disks ( 4 ). A disk ( 4 ) of the rotor ( 2 ) is divided in a circumferential direction ( 5 ) into a plurality of disk sectors ( 6, 7, 8 ) between which magnetic pockets ( 9, 10 ) are designed. Furthermore, the disk ( 4 ) has an inner fastening collar ( 15 ) and connecting members ( 20, 23, 24 ) connecting the disk sectors ( 6, 7, 8 ) to the fastening collar ( 15 ). Such a connecting member ( 20 ) comprises a main web ( 21 ), a side arm ( 30 ) branching off the main rib ( 21 ) in the circumferential direction ( 5 ), and a side arm ( 31 ) branching off the main web ( 21 ) opposite to the circumferential direction ( 5 ). High mechanical stability of the disk ( 4 ) can thus be ensured, wherein magnetic flow losses are reduced.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to an electrical machine, in particular an electric motor having a rotor and a shaft. In particular, the invention relates to the field of electric motors for motor vehicles, in particular electric motors which are used as electrical auxiliary drives for movement, operated by external power, or for assistance to movement, of elements of a motor vehicle. 
     US 2007/0252469 A1 discloses an electric motor having laminates, with magnets being provided in cutouts which extend through the rotor core in the axial direction. These cutouts also have a radial extent. The configuration of the rotor reduces the magnetic flux losses as much as possible. 
     The electric motor which is known from US 2007/0252469 A1 has the disadvantage that flux losses occur via the laminates, or the mechanical load capacity is considerably reduced, depending on the configuration. 
     SUMMARY OF THE INVENTION 
     The electrical machine according to the invention has the advantage that an embodiment is improved with respect to magnetic flux losses and mechanical load capacity. In particular, magnetic flux losses for a predetermined mechanical load capacity can be reduced, or a mechanical load capacity can be improved for predetermined magnetic flux losses. 
     The laminates of the rotor can be joined to a shaft individually, or preassembled as a laminate core, or by means of a plurality of laminate cores. For this purpose, the laminates and/or the laminate cores are at least indirectly connected to the shaft. A plurality of laminates of the rotor, in particular all or virtually all of the laminates of the rotor, have a plurality of laminate sectors in the circumferential direction, between which laminate sectors the magnet pockets are formed, with each of the laminates having an inner attachment crown, with each of the laminates having connection elements which connect the laminate sectors to the attachment crown, and with each of the connection elements having a main web, at least one side arm which branches off from the main web in the circumferential direction, and at least one side arm which branches off from the main web in the opposite direction to the circumferential direction. 
     It is advantageous that one and only one side arm branches off from the main web in the circumferential direction, and/or that one and only one side arm branches off from the main web in the opposite direction to the circumferential direction. This allows a robust configuration of the laminate. The production of the laminate is furthermore simplified and, for example, it may be formed by stamping from a metal sheet. The laminate, which comprises the attachment crown, the connection elements and the laminate sectors, is in this case preferably stamped integrally from a metal sheet. 
     However, another advantage is that a further side arm branches off from the main web at a distance from the side arm in the circumferential direction, and/or that a further side arm branches off from the main web at a distance from the side arm in the opposite direction to the circumferential direction. This allows the main web of the connection element to be connected in each case by two or more arms to the respective laminate sector, both in the circumferential direction and in the opposite direction to the circumferential direction. The configuration of the side arms may in this case be optimized for loads which occur, in particular stresses in the material. In particular, the material of the laminate can be omitted in areas which contribute only a small amount to the component strength, in order to minimize flux losses. 
     In this case, another advantage is that the side arm and the further side arm, which branch off from the main web in the circumferential direction, run together at least in places in the circumferential direction, and that the side arm and the further side arm, which branch off from the main web in the opposite direction to the circumferential direction, run together at least in places in the opposite direction to the circumferential direction starting from the main web. This results in an optimized geometry in which the material of the side arms contributes particularly well to the component strength. The side arms can therefore be made relatively thin, in order to minimize magnetic flux losses. 
     It is also advantageous that the main web of the connection element leads to the attachment crown. In this embodiment, the side arms of the connection elements lead to the individual laminate sectors. 
     In this case, it is advantageous that the side arms of each connection element each lead to one laminate sector, and that the side arms of a connection element and the laminate sector to which the side arms of the connection element lead surround a cutout in the laminate. Specifically, in this embodiment, it is advantageous that the connection element together with the main web and the side arms is at least approximately Y-shaped. In this embodiment, flux losses are reduced in that the flux which runs from a laminate sector having a magnetic north pole to a laminate sector having a magnetic south pole has to travel over a particularly long distance through the metal laminate sheet. In this case, it has to run not only through the upper part of the Y-shaped connection element but also through the lower part of the Y-shaped connection element, specifically the main web, and then further through the attachment crown. The path is therefore particularly long, and the magnetic flux losses are low. 
     It is also advantageous that the side arms of each connection element each lead to adjacent laminate sectors. It is also advantageous here that the main web of the connection element at least approximately on a radial axis of a magnet pocket, which is arranged between the adjacent laminate sectors to which the side arms of the connection element lead. This ensures that the connection of adjacent laminate sectors via the connection elements can be made highly mechanically robust. Furthermore, in this embodiment, a clamping projection can advantageously be provided on the main web, which clamping projection extends along the radial axis to the magnet pocket, with a magnet which is arranged in the magnet pocket being held in the magnet pocket by the clamping projection. The magnet is in this case preferably held in the magnet pocket by a plurality of such clamping projections of a plurality of laminates which are arranged one behind the other. 
     Advantageously, the attachment crown of the laminate can rest at least indirectly on the shaft, and/or can be at least indirectly attached to the shaft. In this case, clamping lugs and centering lugs may be formed on the attachment crown, which face the shaft and are used for alignment of the laminate on the shaft, and for attachment of the laminate to the shaft. 
     It is advantageous that the laminate sectors are connected to one another on a circumference of the laminate on the magnet pockets via webs which are arranged on the outside, or that the laminate sectors are not connected to one another on the circumference of the laminate at the magnet pockets, and holding stops are provided, on which magnets which are arranged in the magnet pockets are supported. This allows optimization to be carried out for the respective application, with respect to mechanical robustness and minimizing flux losses. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred exemplary embodiments of the invention will be explained in more detail in the following description with reference to the attached drawings, in which corresponding elements are provided with matching reference symbols, and in which: 
         FIG. 1  shows a rotor of an electrical machine having a laminate and a shaft, in the form of a schematic illustration corresponding to a first exemplary embodiment; 
         FIG. 2  shows the laminate illustrated in  FIG. 1 , illustrated in the form of a detail corresponding to a second exemplary embodiment, 
         FIG. 3  shows the laminate illustrated in  FIG. 1 , illustrated in the form of a detail corresponding to a third exemplary embodiment, 
         FIG. 4  shows the laminate illustrated in  FIG. 1 , illustrated in the form of a detail corresponding to a fourth exemplary embodiment, and 
         FIG. 5  shows the laminate illustrated in  FIG. 1 , illustrated in the form of a detail corresponding to a fifth exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an electrical machine  1  having a rotor  2  and a shaft  3 , in the form of a schematic illustration corresponding to one exemplary embodiment. In particular, the electrical machine  1  may be in the form of an electric motor and may be used for a motor vehicle. Specifically, the electrical machine  1  is suitable for movement operated by external power of elements of a motor vehicle, for example a sliding roof, a window or a seat element. Furthermore, the electrical machine  1  can be used as an electric motor for steering power assistance. The electrical machine  1  according to the invention is, however, also suitable for other applications. 
     The electrical machine  1  is preferably in the form of a permanent-magnet electrical drive, in which case the rotor  2  may be configured in the form of spokes or as a collector. In this exemplary embodiment, the rotor  2  has a laminate  4  and a multiplicity of further laminates which correspond to the laminate  4 . The laminate  4  is in this exemplary embodiment mounted directly on the shaft  3 . The laminate  4  is subdivided in a circumferential direction  5  into a plurality of laminate sectors  6 ,  7 ,  8 , between which magnet pockets  9 ,  10  are formed. In this case, only the laminate sectors  6 ,  7 ,  8  and the magnet pockets  9 ,  10  are identified, in order to simplify the illustration. 
     In addition, the laminate  4  has an attachment crown  15 , on which a plurality of clamping lugs  16  and centering lugs  17  are formed. The clamping lugs  16  and the centering lugs  17  allow the laminate  4  to be positioned on the shaft  3 , and the laminate  4  on the attachment crown  15  to be attached to the shaft  3 . 
       FIG. 1  shows a radial axis  18  of the laminate sector  7 . The figure also shows a radial axis  19  of the magnet pocket  10 . The laminate sector  7  is symmetrical with respect to the radial axis  18 . The magnet pocket  10  is symmetrical with respect to the radial axis  19 . 
     The laminate sector  7  is connected to the attachment crown  15  via a connection element  20 . In this exemplary embodiment, the connection element is formed from a main web  21 . In this case, the main web  21  extends along the radial axis  18  of the laminate sector  7 . The main web  21  is in the form of an elongated and relatively narrow main web  21 . This results in a certain distance between the laminate sector  7  and the attachment crown  15 . A cavity  22  between a magnet arranged in the magnet pocket  10  and the attachment crown  15  is thus relatively large. Furthermore, this results in a relatively long distance between a magnet such as this and the shaft  3 . 
     Furthermore, the laminate sectors  6 ,  8  are connected to the attachment crown  15  via connection elements  23 ,  24 . In this exemplary embodiment, the connection elements  23 ,  24  are designed in a corresponding manner to the connection element  20 . However, it is also possible for the connection elements  20 ,  23 ,  24  to be formed in two or more different ways. 
       FIG. 2  shows the laminate  4  illustrated in  FIG. 1  in the form of a detail illustration corresponding to a second exemplary embodiment. In this exemplary embodiment, connection elements  20 ,  23  are illustrated which, together with further connection elements, connect the laminate sectors  6 ,  7 ,  8  to the attachment crown  15 . In this case, the laminate sector  7  is connected to the attachment crown  15  both via the connection element  20  and via the connection element  23 . 
     The connection element  20  has the main web  21  as well as a side arm  30  and a side arm  31 . In this case, the side arm  30  branches off from the main web  21  in the circumferential direction  5 , while the side arm  31  branches off from the main web  21  in the opposite direction to the circumferential direction  5 . In this exemplary embodiment, the side arm  30  of the connection element  20  is connected to the laminate sector  7 . The side arm  31  of the connection element  20  is connected to the laminate sector  6 . The connection element  23  is designed in a corresponding manner to the connection element  20  and has a main web  32  and side arms  33 ,  34 . In this case, the side arm  33  branches off from the main web  32  in the circumferential direction  5 , while the side arm  34  branches off from the main web  32  in the opposite direction to the circumferential direction  5 . 
     Therefore, in this exemplary embodiment, the laminate sector  7  is connected on the one hand via the side arm  30  and the main web  32  of the connection element  20  to the attachment crown  15 , and is connected on the other hand via the side arm  34  and the main web  32  of the connection element  23  to the attachment crown  15 . The laminate sector  7  is therefore connected directly to the attachment crown  15  via two connection elements  20 ,  23 . 
     The laminate sector  7 , the side arms  30 ,  34 , the main webs  21 ,  32  and the attachment crown  15  surround a cutout  35  in the laminate  4 . 
     Permanent magnets  36 ,  37  are arranged in the magnet pockets  9 ,  10 , with the magnetic polarity of the permanent magnets  36 ,  37  being illustrated by the letters “N” for north pole and “S” for south pole. Magnetic flux losses occur because of flux through the material of the laminate  4  from north to south. For example, flux occurs from the laminate sector  7 , to which the north poles of the magnets  36 ,  37  are adjacent, to the laminate sectors  6 ,  8 , to which, inter alia, the south poles of the magnets  36 ,  37  are adjacent. 
     By way of example, a magnetic flux occurs from the laminate sector  7  via the side arm  30  and the side arm  31  of the connection element  20 . However, the side arms  30 ,  31  are relatively thin, as a result of which any flux loss relating to them is reduced. A flux via the shaft  3  is reduced by the relatively large cutout  35  and the relatively small main webs  21 ,  32  of the connection elements  20 ,  23 . Flux losses are therefore reduced, thus improving the method of operation of the electrical machine  1 . 
     In the exemplary embodiment illustrated in  FIG. 2 , the connection elements  20 ,  23  are Y-shaped. This results in particularly high strength. Furthermore, a long distance from the shaft  3  can be achieved in this way. 
     With respect to a specific distance along the radial axis  19 , which is ensured by the connection element  23 , the side arms  33 ,  34  are preferably relatively long, while the main web  32  is relatively short. This applies in a corresponding manner to the connection element  20 . This makes it possible to further reduce flux losses since the path of the magnetic flux from the laminate sector  7  to the laminate sectors  6 ,  8  via the connection elements  20 ,  23  can be lengthened in this way. 
     In this exemplary embodiment, the laminate sectors  6 ,  7 ,  8  are not connected to one another on a circumference  40  of the laminate  4  at the magnet pockets  9 ,  10 . However, holding stops  41 ,  42  are provided on the magnet pocket  9 , on which holding stops  41 ,  42  the magnet  36  which is arranged in the magnet pocket  9  is supported on the outside. Correspondingly, holding stops  43 ,  44  are provided on the magnet pocket  10 , and are used to hold the magnet  37 . The holding stop  41  is formed on the laminate sector  6 . The holding stops  42 ,  43  are formed on the laminate sector  7 . The holding stop  44  is formed on the laminate sector  8 . 
       FIG. 3  shows the laminate  4 , as illustrated in  FIG. 1 , of a rotor  2  in the form of a detailed illustration corresponding to a third exemplary embodiment. In this exemplary embodiment, each of the laminate sectors  6 ,  7 ,  8  is individually connected to the attachment crown  15  via a connection element  20 ,  23 ,  24 . By way of example, the laminate sector  7  is connected directly to the attachment crown  15  only via the connection element  20 . The main web  21  of the connection element  20  is arranged at least approximately on the radial axis  18  of the laminate sector  7 . The side arms  30 ,  31  of the connection element  20  lead to the laminate sector  7 , with the side arms  30 ,  31  and the laminate sector  7  to which the side arms  30 ,  31  lead surrounding a cutout  45  in the laminate  4 . The cutout  45  is symmetrical with respect to the radial axis  18 . Furthermore, the cutout  45  is in the form of a droplet, because of the V-shaped arrangement of the two side arms  30 ,  31 . However, the cutout  45  can also be formed in a different manner, in particular in the form of a triangular cutout  45 . 
     The Y-shaped configuration of the connection element  20  with the main web  21  and the side arms  30 ,  31  results in high mechanical strength. This mechanical strength can be optimized in particular by a relatively short main web  21  and correspondingly long side arms  30 ,  31 . The flux losses in this configuration are considerably reduced. This is because flux losses resulting from magnetic flux from the laminate sector  7  to, for example, the laminate sector  6  can pass only over a particularly long path length through the material of the laminate  4 . This path runs not only through the two side arms  30 ,  31  of the connection element  20  but also through the main web  21 . In addition, a certain path length must be traveled via the attachment crown  15  and then via the entire connection element  23 . The path length in this embodiment is therefore particularly long, and the flux losses are correspondingly low. 
       FIG. 4  shows the laminate  4 , as illustrated in  FIG. 1 , of the rotor  2  in the form of a detail illustration corresponding to a fourth exemplary embodiment. By way of example, in this exemplary embodiment, the laminate sector  7  is connected via the connection elements  20 ,  23  to the attachment crown  15  and to the other laminate sectors  6 ,  8 . 
     The main webs  21 ,  32  of the connection elements  20 ,  23  are connected to the attachment crown  15 . The side arms  30 ,  31 ,  33 ,  34  of the connection elements  20 ,  23  are connected to the laminate sectors  6 ,  7 ,  8 . Therefore, the main webs  21 ,  32  lead to the attachment crown, while the side arms  30 ,  31 ,  33 ,  34  lead to the laminate sectors  6 ,  7 ,  8 . In this case, the side arms  30 ,  31  of the connection element  20  lead to mutually adjacent laminate sectors  6 ,  7 . Correspondingly, the side arms  33 ,  34  of the connection element  23  lead to mutually adjacent laminate sectors  7 ,  8 . 
     By way of example, in this exemplary embodiment, the main web  32  of the connection element  23  is arranged on the radial axis  19  of the magnet pocket  10 , and therefore of the magnet  37 . Furthermore, the main web  32  has a clamping projection  46 , which extends along the radial axis  19  of the magnet pocket  10 . In this case, the clamping projection  46  extends as far as the magnet  37  which is arranged in the magnet pocket  10 . 
     In this exemplary embodiment, the laminate  4  has a closed circumference  40 . In this case, the laminate  4  has webs  47 ,  48  which are arranged on the outside on the circumference  40  on the magnet pockets  9 ,  10 . The magnets  36 ,  37  are supported radially on the outside on the webs  47 ,  48 . The magnet  37  is therefore clamped in between the clamping projection  46  and the web  48 . In this case, further clamping projections on further laminates, together with the clamping projection  46 , can hold the magnets  37  in the magnet pocket  10 . 
     Correspondingly, the main web  21  of the connection element  20  has a clamping projection  49 . The configuration of the connection element  20  with respect to the clamping projection  49  and the function for holding the magnet  36  in the magnet pocket  9  are implemented in a corresponding manner. 
     In this exemplary embodiment, the connection elements  20 ,  23  are only partially Y-shaped. In this case, the main web  21  together with the side arms  30 ,  31  of the connection element  20  are Y-shaped, with the clamping projection  49  being provided in addition. 
       FIG. 5  shows a laminate  4  of a rotor  2  of the electrical machine  1  as illustrated in  FIG. 1 , corresponding to a fifth exemplary embodiment. In this exemplary embodiment, the laminate sectors  6 ,  7  are connected to the attachment crown  15  via the connection element  20 . Furthermore, the laminate sectors  7 ,  8  are connected to the attachment crown  15  via the connection element  23 . In this case, the connection element  20  has the side arms  30 ,  31 . In this case, the side arm  30  branches off from the main web  21  in the circumferential direction  5 , while the side arm  31  branches off from the main web  21  in the opposite direction to the circumferential direction  5 . Furthermore, further side arms  30 ′,  31 ′ are provided. In this case, the side arm  30 ′ branches off from the main web  21  in the circumferential direction  5 . The side arm  31 ′ branches off from the main web  21  in the opposite direction to the circumferential direction  5 . In this case, the side arms  30 ,  30 ′ which branch off from the main web  21  in the circumferential direction  5  branch off from the main web  21  at a distance from one another. Furthermore, the two side arms  30 ,  30 ′ run together at least in places, and in this exemplary embodiment completely, in the circumferential direction  5 . The side arms  30 ,  30 ′ and the main web  21  therefore enclose a cutout  50 , which is in the form of a distorted triangle. 
     Correspondingly, the side arms  31 ,  31 ′ of the connection element  20  branch off from the main web  21  at a distance from one another in the opposite direction to the circumferential direction  5 . In this case, the side arms  31 ,  31 ′ run together in the opposite direction to the circumferential direction  5 . 
     The connection element  23  likewise has further side arms  33 ′,  34 ′. The connection element  23  is designed in a corresponding manner to the connection element  20 . In addition, the connection elements  20 ,  23  have short clamping projections  46 ,  49  on their main webs  21 ,  32 , in order to hold the permanent magnets  36 ,  37  in the magnet pockets  9 ,  10 . 
     In this exemplary embodiment, the connection elements  20 ,  23  are approximately Y-shaped, as a result of which mechanical loads which occur in and in the opposite direction to the circumferential direction  5 , in particular mechanical stresses, can advantageously be transmitted from the laminate sectors  6 ,  7 ,  8  to the attachment crown  15 . Furthermore, the mechanical stresses can be transmitted between the laminate sectors  6 ,  7 ,  8 . This results in the laminate  4  having a high mechanical load capacity during operation of the electrical machine  1 , with any stray flux which occurs being reduced. 
     The described exemplary embodiments therefore result in magnetic flux being guided mainly via an air gap on the circumference  40  of the laminate  4  and the stator of the electrical machine  1 . Any stray flux which occurs in this case is largely prevented. 
     Different laminate shapes of the individual laminates which are in layers one behind the other of the shaft  3  can be used for the configuration of the rotor  2  of the electrical machine  1 . In particular, some of the laminates of the rotor  2  may be open on the circumference  40 , as is the case in the exemplary embodiments described with reference to  FIGS. 1 ,  2 ,  3  and  5 . Other laminates may be closed on the circumference  40 , as is the case in the exemplary embodiment described with reference to  FIG. 4 . A single laminate  4  is in this case preferably either closed completely on its circumference  40 , or is open at each magnet pocket, in particular the magnet pockets  9 ,  10 . In this case, holding stops  41  to  44  or webs  47 ,  48  are provided on all the magnet pockets  9 ,  10 . 
     A single laminate  4  of the rotor  2  is preferably formed integrally. In this case, a laminate  4  such as this is preferably stamped from sheet metal, in which case all the structures can be formed by stamping, and in particular the connection elements  20 ,  23 ,  24 , which are described in a different form on the basis of  FIGS. 1 to 5 , can be formed by stamping. In this case, modifications are also possible, depending on the application. In particular, a configuration with more than two side arms  30 ,  31 , for example a configuration with side arms  30 ,  30 ′,  31 ,  31 ′ as is illustrated in  FIG. 5 , can also be used for the arrangement of the connection element  20  as shown in  FIG. 3 , in which in each case one of the laminate sectors  6 ,  7 ,  8  is connected to the attachment crown  15  via one and only one connection element  20 ,  23 ,  24 . 
     The pole linking is also suitable for a consequent-pole arrangement. In this case, only every second rotor pole is formed by a permanent magnet  36 ,  37 . The rotor poles without magnets are in this case necessarily formed by the magnetic return path. 
     Furthermore, the pole linking can also be combined with other measures. For example, a combination with any desired combinations of webs above and below the magnets  36 ,  37  which are inserted into the rotor  2  in the axial direction is feasible, and it is also possible for webs to be omitted. Specifically, a configuration with internal webs can also be implemented in order to hold the magnets  36 ,  37  in the magnet pockets  9 ,  10 , corresponding to the external webs  47 ,  48  on the magnet pockets  9 ,  10  which are illustrated in  FIG. 4 . Furthermore, other measures can also be implemented for clamping the magnets  36 ,  37  in the magnet pockets  9 ,  10 . Furthermore, the attachment crown  15  may be formed in a different manner, in order to form an interface between the laminate  4  and the shaft  3 . 
     It is also possible for remaining openings or gaps to be filled with plastic or a clamping substance. Specifically, the magnets  36 ,  37  can be fixed by adhesive bonding, extrusion coating with plastic or the like. However, additional components can also be used for attachment of the magnets  36 ,  37 , in particular spring elements. Holding stops which are in the form of internal holding stops on the laminate  4  can also be used for attachment of the magnets  36 ,  37 . 
     In addition, the laminate  4  may have contours in a different form on the circumference  40 . Specifically, a suitable contour can be provided in order to reduce the locking torque, for example a sinusoidal pole contour. 
     In order to further reduce the flux losses, that is to say a stray flux, it is also possible to use laminates  4  during construction of the rotor  2  in which the pole linking is dispensed with in one or more metal sheets in the axial direction. The metal laminate sheets, which are then loose, may, for example, be mounted in the laminate core of the rotor  2 , for example, by packaging points or via closed external webs. Correspondingly, the magnet attachment may be provided in only some metal sheets. In addition, it is not necessary to provide every connection element  20 ,  23 ,  24  in a laminate  4 . Specifically, only every second or third connection element may be provided. In this case, laminate sectors  6 ,  7 ,  8  can be attached to the attachment crown  15  via other laminates. 
     The invention is not restricted to the described exemplary embodiments.