Abstract:
A magnet pole, for magnetically levitated vehicles, includes a core ( 10 ) and a winding provided with winding disks that are arranged axially on top of each other. Both of the disks contain conduction band sections ( 6   a   , 6   b ) that are wound counter to the direction of winding and in several layers about the core ( 10 ). The conduction band sections are connected together in an electrically conductive manner by means of a connection part ( 1 ) on the core ( 10 ) near ends. The connection part ( 1 ) is bent in an outward manner on lateral longitudinal edges that are parallel to each other thus forming a curved outlet ( 12   a   , 12   b ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a United States National Phase application of International Application PCT/DE2007/001577 and claims the benefit of priority under 35 U.S.C. §119 of German Patent DE 10 2006 049 716.3 filed Oct. 12, 2006, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention pertains to a magnet pole for magnetic levitation vehicles with a core and with a winding, which is wound on same and has two disks located one on top of another, wherein the two disks contain two conduction band sections, which are wound around the core and are connected to one another in an electrically conductive manner by a middle connecting part forming a first layer on the core at ends located close to the core. 
       BACKGROUND OF THE INVENTION 
       [0003]    Magnet poles of this type are used in many different forms in magnetic levitation vehicles, e.g., as parts of carrier, guide or brake magnets. To reduce cooling and insulation problems, they contain at least two disks, which are located at spaced locations from one another in the axial direction of the core and are insulated by suitable insulation layers against each other and against the core (DE 10 2004 011 940 A1). It is advantageous for electrical reasons to connect the two disks to one another electrically in an area close to the core, because this eliminates the need for arranging electrical terminals led through inwardly and terminating between the core and the first layer. Magnet poles of the class described in the introduction are therefore also known (DE 10 2004 011 942 A1), which make possible a cost-effective connection between the two disks in the area of the core, which said connection can be established without complicated insulation measures. 
         [0004]    It was observed during the practical use of such magnet poles that the insulation of the disks against the core is not yet satisfactory. Electric breakdowns, which destroy the insulation, may occur when thin insulation layers are used in the area of the core, which would be favorable for heat dissipation over the core acting as a cooling body. By contrast, the cooling action is reduced if thick insulation layers are used, which reliably prevent electric breakdowns. 
       SUMMARY OF THE INVENTION 
       [0005]    Based on this, the basic technical object of the present invention is to design the magnet pole of the class described in the introduction such that no harmful potential increases leading to electric breakdowns will occur even when a comparatively thin insulation layer surrounding the core is used. 
         [0006]    According to the invention, a magnet pole is provided for magnetic levitation vehicles with a core and with a winding, which is wound on same and has two disks located one on top of another, wherein the two disks contain two conduction band sections, which are wound around the core in opposite winding directions and in a plurality of layers and are connected to one another in an electrically conductive manner by a middle connecting part forming a first layer on the core at ends located close to the core. The connecting part is bent over to the outside at mutually parallel, lateral longitudinal edges, forming an arc-shaped end each. 
         [0007]    The present invention is based on the assumption that at least part of the harmful potential increases is caused by the lateral edges of the first layer formed by the connecting part. By contrast, it is achieved by the bent-off edges of the connecting part according to the present invention that no harmful peak discharges will occur any more in the edge areas and the insulation layer is not therefore stressed more at its axial edges than in the middle parts of the core. It is therefore possible to use thin insulating films throughout, which has a favorable effect on heat dissipation. 
         [0008]    The connecting part may advantageously have two terminal ends which set the distance between the two disks and are connected to one of the conduction band sections each. 
         [0009]    The arc-shaped ends may have a somewhat greater length in the circumferential direction of the core than would correspond to the circumference of the core and may be placed with an overlap at the ends facing each other. 
         [0010]    The connecting part may advantageously be an essentially rectangular, flat shaped part, which has one of the terminal ends each at ends located opposite. 
         [0011]    The overlap of the arc-shaped ends may be obtained by an oblique cut of end edges of the connecting part, which end edges adjoin the end sections. 
         [0012]    The present invention will be explained in more detail below in connection with the attached drawings on the basis exemplary embodiments. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    In the drawings: 
           [0014]      FIG. 1  is a top view of a first exemplary embodiment of a connecting part according to the present invention, which is suitable for connecting two disks intended for the winding of a magnet pole; 
           [0015]      FIG. 2  is a top view of a detail of the connecting part according to  FIG. 1  with a conduction band section fastened to this for a first disk of a winding; 
           [0016]      FIG. 3  is a top view of the connecting part, which view corresponds to  FIG. 1 , but with an insulating film placed on this connecting part; 
           [0017]      FIG. 4  is a top view corresponding to  FIG. 2 , but with an additionally inserted insulating film corresponding to  FIG. 3 ; 
           [0018]      FIG. 5  is a schematic and perspective partial view of the connecting part according to  FIGS. 1 through 4  in the area of a butt joint; 
           [0019]      FIG. 6  is a schematic sectional view through a magnet pole with a winding prepared corresponding to  FIGS. 1 through 5 ; and 
           [0020]      FIG. 7  is a top view of a second exemplary embodiment of the connecting part according to the present invention, which top view corresponds to  FIG. 1 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    Referring to the drawings in particular, Magnet poles that have a core and windings consisting of two disks are generally known. These two disks are located one on top of another in the axial direction of an axis of the core and preferably have the same number of layers. These are electrically insulated against one another by insulating films, on the one hand, and against the core by an additional insulating layer, on the other hand. In addition, the layers of one disk are preferably wound around the core in an opposite winding direction compared to the other disk. The disks are electrically connected to one another by a connecting part at their layers located innermost. 
         [0022]    According to  FIG. 1 , such a connecting part  1  intended for connecting two disks of a winding has a middle section  2  with a central or longitudinal axis  3  and with a width that corresponds essentially to the height of a core, not shown, and is measured at right angles to the longitudinal axis  3 . The middle section  2  ends at end edges  2   a  and  2   b  each extending at right angles to the longitudinal axis  3 . In addition, the middle section  2  has a first terminal end  4   a  at the right end according to  FIG. 1  and in its upper half according to  FIG. 1  and a second terminal end  4   b  at its left-hand end and in its lower half in  FIG. 1 . Both terminal ends  4   a ,  4   b  are of a strip-shaped design, directed opposite each other, extend beyond the corresponding end edge  2   a ,  2   b  and in parallel to the longitudinal axis  3  and are somewhat less wide than half the width of the middle section  2 . 
         [0023]    The terminal ends  4   a ,  4   b  end, corresponding to  FIG. 1 , at end edges  2   c  and  2   d  extending at right angles to the longitudinal axis  3  and are used in the known manner to connect a line band section each. This is shown in  FIG. 2  on the basis of a line band section  6   b  connected to the terminal end  4   b . It is clear that the other terminal end  4   a  is connected to a corresponding line band section  6   a  (e.g.,  FIG. 5 ). 
         [0024]    The connecting part  1  and the conduction band sections  6   a ,  6   b  consist of a material with good conductivity, e.g., aluminum, and are preferably connected to one another by welding. This is indicated in  FIG. 2  by weld points  7 , which are formed in short overlapping areas between the terminal ends  4   a ,  4   b  and the conduction band sections  6   a ,  6   b . Broken lines  6   c  and  6   d  (cf.  FIG. 5 ) indicate the end edges of the conduction band sections  6   a ,  6   b , which said end edges end at the connecting part  1 . Since  FIGS. 1 and 2  show a top view of a surface of the connecting part  1  facing away from the core, the broken lines  6   c ,  6   d  indicate, furthermore, that the conduction band sections  6   a ,  6   b  in  FIGS. 1 through 5  are located under the terminal ends  4   a ,  4   b.    
         [0025]    The two terminal ends  4   a ,  4   b  and consequently also the conduction band sections  6   a ,  6   b  connected to them are located at right angles to the longitudinal axis  3  at a distance a ( FIG. 1 ) that corresponds to the distance between the two disks in the finished state of the winding. The distance between the disks is therefore defined unambiguously by the design of the connecting part  1 . 
         [0026]    In the direction of the longitudinal axis  3  the middle section  2  has a length  1  ( FIG. 1 ) measured between the two end edges  2   a ,  2   b , which is preferably equal to the circumference of the wound-over core after application of the insulating layer surrounding it. 
         [0027]      FIGS. 3 and 4  show that a strip-shaped insulating film  8   a  and  8   b  each also comes to lie under the conduction band sections  6   a ,  6   b  and the corresponding terminal ends  4   a ,  4   b . In particular,  FIG. 3  shows only the respective terminal ends  4   a  and  4   b  and the insulating films  8   a  and  8   b , which end on the side of the middle section  2  at end edges  8   c ,  8   d  indicated by broken lines. By contrast,  FIG. 4  also shows, in addition to the left-hand insulating film  8   b , the conduction band section  6   b  connected to the terminal end  4   b  analogously to  FIG. 2 . The insulating films  8   a  and  8   b  are used to mutually insulate the layers of the winding to be prepared with the conduction band sections  6   a ,  6   b , on the one hand, and to insulate the end sections thereof against the connecting part  1 , on the other hand. The end edges  8   c ,  8   d  of the insulating films  8   a ,  8   b  are located for this reason farther inwardly in the middle section  2  compared to the end edges  6   c ,  6   d  of the conduction band sections  6   a ,  6   b.    
         [0028]      FIG. 5  schematically shows the winding of a core  10  with the winding according to  FIGS. 1 through 4 . The middle section  2  is placed first on the core  10  for this purpose and wound once around this. The terminal ends  4   a ,  4   b  begin in the area of a joint site  11  or of a narrow gap between the two end edges  2   a ,  2   b  of the middle section  2 , which said gap is shown as an exaggeratedly large gap in  FIG. 5 , and the conduction band sections  6   a  and  6   b  connected to these terminal ends begin somewhat farther on the outside, while the insulating films  8   a ,  8   b  inserted end closer to the gap  11  and overlap the gap area. It can be clearly recognized from  FIG. 5  that the connecting part  1  also sets, based on the described design, that the conduction band section  6   a  is to be wound counterclockwise and the conduction band section  6   b  clockwise around the core  10 , i.e., the connecting part  1  sets not only the distance a ( FIG. 1 ) but also the direction of winding of the two conduction band sections  6   a ,  6   b.    
         [0029]    Magnet poles of this type are known, e.g., from DE 10 2004 011 940 A1 (corresponding to US2008143467) and DE 10 2004 011 942 A1 (corresponding to US2009021335). Reference is therefore made to these documents to avoid repetitions of further details, and these are hereby made the subject of the present disclosure by reference (corresponding U.S. patent applications US2008143467 and US2009021335 are hereby incorporated by reference). Only the features of such magnet poles that are essential for the present invention will be explained in more detail below. 
         [0030]    According to the present invention, the middle section  2  of the connecting part  1  has two lateral longitudinal edges  2   e  and  2   f , which extend in parallel to the longitudinal axis  3  and are bent over to the outside, forming arc-shaped ends  12   a ,  12   b . The ends  12   a ,  12   b  are limited in  FIGS. 1 through 4  by lines  14  extending in parallel to the longitudinal axis  3  and are indicated above all in  FIG. 5  by areas drawn in broken lines. The ends  12   a ,  12   b  extend, like the middle section  2 , over a length that corresponds essentially to the circumference of core  10 . Therefore, the ends  12   a ,  12   b  end likewise, as is shown in the lower part of  FIG. 5 , at the gap  11 . 
         [0031]    As is also shown in  FIGS. 1 through 4 , the connecting part  2  ends at the respective end edges  2   a  and  2   b  extending at right angles to the longitudinal axis  3 . Since, moreover, the distance a is present between the terminal ends  4   a ,  4   b , an open slot  15 , which is not covered either by the terminal ends  4   a  and  4   b  or by the conduction band sections  6   a  and  6   b  and the insulating films  8   a ,  8   b , is formed after the core  10  has been wound around in the area of the joint site  11 . This slot  15  is needed, however, for avoiding mutual contacts between the two terminal ends  4   a ,  4   b  and hence electric breakdowns. In order to nevertheless avoid undesired potential increases in this area, slot  15  is advantageously covered with a partially conductive film  16 , which lies on the insulating layer of the core  10  and is schematically indicated by a circle drawn in broken line in  FIG. 5 . The partially conductive film  16  consists, e.g., of an organic insulating material mixed with carbon black and is suitable for draining off capacitive currents without letting through operating currents. The risk of peak discharges in this area is further reduced hereby. 
         [0032]      FIG. 6  shows a partial cross section through a magnet pole, which has the core according to  FIG. 5 , a central axis  17  and a disk  18  of a winding, which said disk is shown only partially. Core  10  is surrounded at first by an insulating layer  19 , on which the connecting part  1  is wound corresponding to  FIGS. 1 through 5 . Clearly visible here is the upper end  12   a , which has an arc-shaped course and ends approximately at the level of the upper longitudinal edge of the conduction band section  6   a  forming the disk  18  or even somewhat above it. Arrows  20  in  FIG. 6  indicate that the core  10  and the connecting part  1  form the two electrodes of a plate capacitor, which has an essentially constant plate distance in an area located between the ends  12   a ,  12   b  ( FIG. 5 ), so that a homogeneous electrical field develops there during the operation of the magnet pole. The two ends  12   a  and  12   b  ensure according to the present invention at the upper and lower edges of this plate capacitor that the electrical field is not increased there by edge effects, but is rather decreased continuously. This leads to the advantage, described in the introduction, that the insulation layer  19  is not exposed to higher stresses at the lateral edges than in the inner, homogeneous part. 
         [0033]    A further reduction of the stress on the insulation layer  19  during operation is achieved according to the present invention by an oblique cut of the end edges  2   a  and  2   b , as it is shown in  FIG. 7  on the basis of the exemplary embodiment of the connecting part  1  according to the present invention that is currently considered to be the best. The end edges  2   a ,  2   b  are beveled, starting from the longitudinal edges  2   e  and  2   f , especially towards the center of the middle section  2 , so that they form an acute angle α with the end edges  2   e ,  2   f  and end at the corresponding terminal ends  4   a ,  4   b , forming corresponding acute angles β. In particular, the arrangement is selected to be such that the ends  12   a ,  12   b  are located closer opposite each other after the core  10  has been wound around according to  FIG. 5  than the gap  11  shown in  FIG. 5 . In addition, the two end edges  2   a  and  2   b  extend here to the outside, starting from a smallest possible slot  15 , obliquely rather than at right angles to the longitudinal axis  3 . Based on this design of the end edges  2   a ,  2   b , it is even possible to place the two ends  12   a ,  12   b  with a preselected overlap  21  indicated schematically in  FIG. 5  for the end  12   a  in the area of gap  11 , and a dotted line  22  is to indicate the end edge  2   a  extending obliquely here. At the same time, the insulating films  8   a  and  8   b  can be used in this case to electrically insulate the two overlapped parts in order to avoid short-circuits in this area. On the whole, it is achieved by the measures described on the basis of  FIG. 7 , which are taken preferably in addition to the partially conductive film  16 , that the insulating layer  19  ( FIG. 6 ) will not be stressed excessively by potential increases inevitably occurring in the area of gap  11  and of slot  15 . 
         [0034]    The present invention is not limited to the exemplary embodiments described, which can be varied in many different ways. This applies especially to the shape of the connecting part  1  selected in the particular case, which may comprise, e.g., a shaped part prepared by punching. The ends  12   a ,  12   b  may also be prepared, in principle, as desired. It is advantageous for the purposes of the present invention to prepare the bent parts by cold working of the edge areas of the connecting part  1  in a compression mold or the like. The radii of curvature in the area of the bent parts are to be selected depending on the particular case. Furthermore, the potential increases can be reduced in an area close to the core  10  by imparting a gradually increasing width on the conduction band sections  6   a  and  6   b  starting from the terminal ends  4   a  and  4   b , as this is indicated in  FIGS. 2 and 4  at the left-hand end of the conduction band section  6   b . The edges of the layers located innermost are flatly covered as a result in the area of the ends  12   a ,  12   b  of the finished winding by additional layers located farther to the outside (cf.  FIG. 6 ), as this was already described, in principle, e.g., in DE 10 2004 011 941 A1 and DE 10 2004 011 942 A1. Furthermore, it is possible to form the magnet pole in an analogous design from more than two disks located one on top of another in the direction of the axis of the core  10 . Finally, it is obvious that the different features may also be used in combinations other than those described and shown. 
         [0035]    While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.