Abstract:
The invention proposes a transverse flux machine, in particular a unipolar transverse flux machine, with at least one stator module contained in a housing composed of two axially joined housing parts and having an annular coil disposed concentric to the housing axis as well as stator elements that embrace this annular coil from the outside and inside. For ease of assembly of the individual parts and for a precisely toleranced maintenance of a small air gap between the stator and the rotor, clamps that protrude axially from the respective housing parts oriented toward each other are provided for the stator elements and have positioning elements for securing them in the radial direction.

Description:
BACKGROUND OF THE INVENTION  
       FIELD OF THE INVENTION  
         [0001]    The invention is directed to an transverse flux machine, in particular a unipolar transverse flux machine.  
         DESCRIPTION OF THE PRIOR ART  
         [0002]    In a known unipolar transverse flux machine (DE 100 39 466 A1), the housing that contains the stator module is comprised of two identically designed half shells, which are placed against each other in mirror image fashion, with the stator module enclosed between them. Each half shell has a screen-like structure with an inner ring and a concentric outer ring, which are of one piece with each other and are connected to each other by means of radial fins. The half shells contain on the one hand, radial grooves to accommodate the stator yokes, which span the inner ring, radial fin, and outer ring, and on the other hand, radial grooves for the insertion of the stator fins, which span only the inner ring. In addition to these radial grooves, the two half shells that are placed against each other in mirror image fashion have opposing recesses that are disposed concentric to the housing axis and are for accommodating the annular coil of the stator module. The stator yoke and the radial grooves are matched to each other so that when the stator yokes and stator fins are inserted into the associated radial grooves, the two half shells of the housing are secured in a radially and axially stationary fashion. To this end, on both sides of their crosspiece, the stator yokes each have a hook protruding radially outward, which when the stator yoke is inserted into the radial groove, positively engages with a radial fin in the two half shells, at their rear end oriented away from the radial groove. At the end of each radial groove disposed in the outer ring, a radial recess is let into the groove bottom to accommodate the stator yokes and the radial depth of this radial recess is sized so that when the stator yoke is inserted into the radial groove in the proper position, the base of the hook comes into contact with the bottom of the recess. As a result, on the one hand, the stator yokes are positioned in a precisely toleranced fashion in the radial direction and on the other hand, the two half shells are clamped to each other axially.  
         OBJECTS AND SUMMARY OF THE INVENTION  
         [0003]    The transverse flux machine or unipolar transverse flux machine according to the invention has the advantage over the prior art of a simple assembly through simple joining processes of the individual parts, which assures the maintenance of the particularly small air gap between the rotor and stator that is required in this kind of motor design.  
           [0004]    According to an advantageous embodiment of the invention, the clamps protrude axially from radial plane surfaces of the housing parts that are oriented toward each other, and the radial leading edges of the stator elements are inserted into the clamps. Clamps that are designed in this way can easily be formed onto the housing parts by means of a simple injection mold formation when these parts are injection molded.  
           [0005]    According to an advantageous embodiment of the invention, the corresponding positioning elements for radially position the stator elements are constituted by acute-angled notches in the radial leading edges of the stator elements and by acute-angled protuberances that engage positively in the notches and are disposed on the clamps provided on the housing parts.  
           [0006]    According to a preferred embodiment of the invention, the annular coil is contained in a coil body that is provided with slots for the insertion of the stator elements. The slot width of the slots is greater than the thickness of the stator elements so that they are accommodated in the slots with a certain amount of play. The distance of the slots from one another in the circumferential direction corresponds to the spacing between the stator elements. These slots provided in the coil body permit the stator elements to be prepositioned on the annular coil during assembly so that by axially sliding the two housing parts onto the coil body, the stator elements are inserted with their radial leading edges into the associated clamps on the radial plane surfaces of the two housing parts, and after being pressed together with the two housing parts, are secured in an axially stationary fashion and are precisely positioned in the radial direction by means of the positioning elements. This prepositioning of the stator elements does not require the stator elements, which are usually comprised of a number of laminations, to be subjected to any bundling processes; they can instead be inserted loosely into the slots of the coil body.  
           [0007]    According to an advantageous embodiment of the invention, in the housing, which is made of magnetically nonconductive material, the one housing part is cup-shaped, the other housing part is disc-shaped, and each housing part contains a central recess. Since for reasons of a reliable run-up of the transverse flux machine, usually at least two stator modules are disposed next to each other axially and are optionally rotated by 90° electrically in relation to each other, the two disc-shaped housing parts rest directly against each other with their disc surfaces oriented away from the clamps and are embraced by the cup-shaped housing parts of the two stator modules, with the circular ring-shaped cup edges of the cup-shaped housing parts contacting each other. This has the advantage that in a two-strand embodiment of the machine, the housing parts for the two stator modules can be produced identically and need only be rotated in relation to each other in order to produce a relative rotation angle position of 90° in relation to each other. If rotor modules of the machine disposed axially next to each other are already rotated by a rotation angle offset of 90° electrically in relation to each other, then the two disc-shaped housing parts of the stator modules can be joined together without being rotated and are held against each other when the two cup-shaped housing parts are attached to each other by an axial pressing force. Naturally the two disc-shaped housing parts can also be additionally connected to each other or can be of one piece with each other. The latter case, however, eliminates the above-described manufacturing advantage of identically embodied housing parts.  
           [0008]    According to a preferred embodiment of the invention, the electrical supply to the two annular coils in the stator modules is disposed between the two disc-shaped housing parts in the form of a pressed screen. This makes it easier to route the electric coil connections from the two stator modules. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawings, in which:  
         [0010]    [0010]FIG. 1 shows part of a longitudinal section through a two-strand transverse flux machine, in a perspective depiction,  
         [0011]    [0011]FIG. 2 is a perspective depiction of the two-strand transverse flux machine in FIG. 1, after the removal of the two cup-shaped housing parts of the housings of the stator modules,  
         [0012]    [0012]FIG. 3 shows a detail of the same depiction as FIG. 2, with the stator yokes removed,  
         [0013]    [0013]FIG. 4 shows the same depiction as in FIG. 3, with the annular coil removed,  
         [0014]    [0014]FIG. 5 shows an exploded view of the housing of the stator module that is disposed at the rear in FIG. 2, and  
         [0015]    [0015]FIG. 6 is a longitudinal section through half of a two-strand unipolar transverse flux machine. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]    The transverse flux machine partly shown in FIG. 1 and the unipolar transverse flux machine partly shown in FIG. 6 each have a stator  11  and a rotor  12  that rotates in the stator  11  and is supported in a rotationally fixed manner on a rotor shaft  13 . The stator  11  includes two stator modules  14  resting directly against each other in the axial direction (also see FIG. 2), and the rotor  12  includes two rotor modules  15  disposed axially one after the other in a rotationally fixed manner on the rotor shaft  13 . Each stator module  14  is contained in a housing  16  made of magnetically nonconductive material, e.g. aluminum or plastic, which is composed of an outer, cup-shaped housing part  161  and an inner, disc-shaped housing part  162  (FIG. 5). As can be seen in FIG. 5 and particularly in FIG. 6, the two disc-shaped housing parts  162  of the two housings  16 , each of which contains a stator module  14 , rest directly against each other and are embraced by the two cup-shaped housing parts  161  of the housings  16 , which rest against each other with their circular ring-shaped cup edges. Each housing part  161 ,  162  has a central opening  17  or  18 ; the central openings  17  of the two outer, cup-shaped housing parts  161  each accommodate a bearing plate  19  in which the rotor shaft  13  is supported in rotary fashion by means of a pivot bearing  20 .  
         [0017]    The design of a stator module  14  is described in detail in DE 100 39 466 A1 and is therefore only discussed briefly here. The stator module  14  has an annular coil  21 , which is disposed concentric to the axis of the stator, rotor, or housing and is contained in a coil body  22 . The annular coil body  22  has a U-shaped cross section, whose U-opening points outward, i.e. is oriented toward the cup-shaped housing part  161 . As depicted in FIGS. 1, 2, and  3 , the coil body  22  has two parallel, annular legs  221  and  222  and an annular crosspiece  223  that is of one piece with these two legs and connects them together. The annular coil  21  is accommodated between the legs  221  and  222  and is wound onto the crosspiece  223 . The coil body  22  with the annular coil  21  inside it is embraced from the outside by U-shaped stator yokes  23  that are disposed equidistantly in the circumference direction of the annular coil  21 , while on the inner circumference of the coil body  22 , stator fins  24  that are also equidistantly spaced span the coil body  22  in the axial direction. The distance of the stator yokes  23  from each other and the distance of the stator fins  24  from each other are the same, and the stator fins  24  are disposed rotated by half this distance in relation to the stator yokes  23 . The stator yokes  23  and the stator fins  24  constitute the n stator poles of the transverse flux machine or the unipolar transverse flux machine, the spacing between the n/2 stator yokes  23  and the n/2 stator fins  24  corresponding to a pole pitch. The stator yokes  23  and stator fins  24  are shifted by half a pole pitch in relation to one another. Each stator yoke  23  and each stator fin  24  is comprised of a number of sheet metal laminations resting against one another.  
         [0018]    The stator yokes  23  and the stator fins  24 —referred to below jointly as stator elements—are disposed radially opposite from the rotor module  15 , with a very small air gap  25  left between them (FIG. 6). The designs of the rotor module  15  of the transverse flux machine in FIG. 1 and the rotor module of the unipolar transverse flux machine according to FIG. 6 are not discussed in detail here because they are not relevant. In this connection, the reader is referred to Michael Bork, “Development and Optimization of a Production-Oriented Transverse Flux Machine” [Entwicklung und Optimierung einer fertigungsgerechten Transversalfluβmaschine], Diss. 82, RWTH Aachen, Shaker Verlag, Aachen, 1997, p. 8 ff. for the transverse flux machine, and to DE 100 39 466 A1 for the unipolar transverse flux machine. In both machines, it is necessary that the air gap  25  between the stator module  14  and the rotor module  15  be as small as possible, thus requiring the stator elements  23 ,  24  to be positioned very precisely in the radial direction.  
         [0019]    For the sake of a simple production of the stator module  14  by means of joining techniques, which can be automated very easily, in each housing  16 , the radially extending plane surfaces  161   a  and  162   a  of the two housing parts  161 ,  162  oriented toward each other are each provided with an inner row  26  of equidistantly disposed clamps  27  concentric to the housing axis and an outer row  28  of equidistantly disposed clamps  29  concentrically encompassing the first row  26  of clamps. Between the clamps  27  of the inner row  26 , positioning elements  31  are provided, which correspond to positioning elements  32  embodied on the radially extending leading edges of the stator fins  24  in such a way that they secure the stator fins  24  in the radial direction. Between the clamps  29  of the outer row  28 , positioning elements  33  are provided, which correspond to positioning elements  34  on the radially extending leading edges of the stator yokes  23  or their yoke legs in such a way that they radially secure the stator yokes  23  in the same fashion. As FIGS. 4 and 5 depict for the disc-shaped housing part  162 , the clamps  27 ,  29  in the two rows  26 ,  28  are embodied identically and are each comprised of two retaining slats  35  that are spaced apart from each other and protrude axially from the plane surface  161   a  of the disc-shaped housing part  162 , whose spacing is slightly greater than the thickness of the stator fins  24  and the stator yokes  23 . The clamps  27 ,  29  on the plane surface  161   a  of the cup-shaped housing part  161  (FIGS. 1 and 6) that are not shown in FIGS.  2  to  5  are embodied identically to the clamps  27 ,  29  on the disc-shaped housing part  162 . The positioning elements  32 ,  34  disposed on the stator elements, i.e. the stator fins  24  on the one hand and the stator yokes  23  on the other, are constituted by acute-angled notches  36  in the radially extending leading edges of the stator elements  24 ,  23 , while the positioning elements  31 ,  33  disposed in the clamps  27 ,  29  are constituted by acute-angled protuberances  37  that extend between the retaining slats  35 . As FIG. 4 shows only for the stator fins  24  in connection with the disc-shaped housing part  162 , after the assembly of the stator module  14 , the stator elements  24 ,  23  are positively engaged by the clamps  27 ,  29  and are fixed in a manner that prevents them from moving in the circumferential direction. At the same time, as shown in FIGS. 1 and 6, the positioning elements  31  and  32  on the one hand and  33  and  34  on the other, positively engage with one another so that a highly precise fixing of the stator elements  24 ,  23  in the radial direction is assured particularly if the stator fins  24  and stator yokes  23  are axially pressed against both of the housing parts by an axial joining force F exerted on the housing parts (FIG. 6).  
         [0020]    In order to simplify the joining process of the stator elements  23 ,  24 , the coil body  22  of the annular coil  21  is used to fix the position of the stator elements  23 ,  24  ahead of time in such a way that when the two housing parts  161 ,  162  are slid onto the prepositioned stator elements  23 ,  24 , these elements  23 ,  24  are automatically inserted into the clamps  27 ,  29  in the two rows  26 ,  28  on each housing part  161 ,  162 . To this end, the coil body  22  is provided with slots  38  for the insertion of the stator fins  24  and with slots  39  for the insertion of the stator yokes  23  (FIG. 3). The distance of the slots  38  and  39  from one another corresponds to the pole pitch, the slots  38  once again being shifted in the circumferential direction of the coil body  22  by one half pole pitch in relation to the slots  39 . The slot width is designed to be slightly greater than the thickness of the stator fins  24  and stator yokes  23  so that these have a slight play when they are disposed in the slots  38 ,  39 . Preferably, for each stator fin  24  or each stator yoke  23 , a packet of sheet metal laminations is inserted into the slots  38  and slots  39 , and these laminations are preferably not attached to one another in advance, but can also be press-bundled ahead of time. Depending on the form of the stator yokes  23  or the stator fins  24 , the slots  39  extend along the annular legs  221 ,  222  and across the free, outer end surfaces of the legs  221 ,  222  of the coil body  22 , while the slots  38  are let as axial slots into the annular crosspiece  223  of the coil body  22 .  
         [0021]    The assembly of the stator module  14  occurs with the simple joining technique of the stator elements  23 ,  24  in that first, the stator yokes  23  are inserted into the coil body  22  and then are slid with their one yoke leg into the clamps  29  of the outer second row  28  of one of the two housing parts, e.g. the disc-shaped housing part  162 . Then the stator fins  24  are slid through the slots  38  into the clamps  27  of the inner row  26 . Then the other housing part, e.g. the cup-shaped housing part  161 , is slid onto the coil body  22  with the prepositioned stator elements  23 ,  24  so that the clamps  29  embrace the other yoke leg of the stator yokes  23  and the clamps  27  embrace the other radial leading edge of the stator fins  24 , and the protuberances  37  between the clamps  29 ,  27  protrude into the notches  36  on the stator yokes  23  and stator fins  24 . The second stator module  14  is assembled in the same manner. The two stator modules  14  are placed axially against each other in the correct position so that the housing axes are aligned with each other. The one housing  16  is possibly rotated by 90° electrically in relation to the other housing  16 . Then the two outer, cup-shaped housing parts  161 , which axially embrace the two inner, disc-shaped housing parts  162  and are oriented with their annular housing edges toward each other, are pressed together by means of an axial joining force F (FIG. 6), causing the stator elements  23 ,  24  to be pressed axially into the clamps  29 ,  27  and the protuberances  37  to be pressed with no tolerance into the notches  26 . The joining force F is maintained while the two housing parts  161  are attached to each other, for example by means of laser welding or ultrasonic welding.  
         [0022]    Naturally it is possible to embody the two disc-shaped housing parts  162  of the two housings  16  that each enclose a stator module  14 , as being of one piece with each other. In this case, the clamps  27 ,  29  and the positioning elements  31  and  33  must be embodied on the two opposite planar disc surfaces of the disc-shaped housing part  162  that is shared by the two housings  16 . If it is necessary for the stator modules  14  to be shifted by 90° electrically in relation to each other, then the clamps  27 ,  28  on the one disc surface of the shared housing part  162  must be disposed rotated by 90° in relation to the position of the clamps  27 ,  29  on the other disc surface. The assembly of such a two-strand transverse flux machine or unipolar transverse flux machine occurs in the same manner as described previously, in which first, the one stator module  14  is assembled and covered by the cup-shaped housing part  161  and then the second stator module  14  is assembled and covered by the second cup-shaped housing part  161 , whereupon the two outer housing parts  161  are welded to each other during exertion of an axial joining force F on the two housing parts  161 .  
         [0023]    It is particularly advantageous if the strip conductors for electrically connecting the two annular coils  21  in the two stator modules  14  are routed between the two disc-shaped housing parts  162  that rest against each other or, in the case of the one-piece disc-shaped housing part  162  that is shared by the two housings  16 , are routed inside the shared housing part  162 . These strip conductors are preferably produced in the form of a stamped screen, which is either clamped between the two disc-shaped housing parts  162  or is cast into the shared disc-shaped housing part  162 . The housing parts  161 ,  162  are made of plastic or aluminum, through the use of a molding or casting process.  
         [0024]    The foregoing relates to preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.