Abstract:
A reception unit is provided including a receiver coil for the contactless transfer of electric energy. The receiver coil includes a plurality of flux guiding elements ( 16   a,    16   b ) that are made of a highly permeable material and that are designed to concentrate the field lines. The flux guiding elements ( 16   a,    16   b ) form a continuous molded part that is embodied in a base body ( 18 ) and that is combined with the base body to form a component that can be completely prefabricated. The molded part is produced by casting and the base body ( 18 ) is used as a casting mold.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a United States National Phase application of International Application PCT/DE2007/001567 and claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2006 048 829.6 filed Oct. 11, 2006, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention pertains to a receiving unit with a receiver coil for the contactless transmission of electric power, wherein a plurality of flux-conducting elements, which are intended to concentrate lines of flux and which consist of a material with high permeability compared to that of air, are associated with the receiver coil and the present invention pertains to a process for manufacturing such a receiving unit. 
       BACKGROUND OF THE INVENTION 
       [0003]    Receiving units of this type are known (DE 10 2004 056 439 A1). They are used especially in magnetic levitation trains for the contactless, inductive transmission of electric power from a track to a vehicle. At least one primary conductor, which is designed as a transmitting coil and is connected to a power source, is provided for this purpose at the track and at least one secondary receiver coil is provided at the vehicle. This coil is preferably designed as part of a receiving unit and is fastened with this to a magnetic back box, which has the carrier magnets and is in turn connected to an undercarriage or body of the vehicle via frame straps. 
         [0004]    To improve the magnetic coupling between the primary conductor and the receiver coil and to avoid eddy current losses, the receiver coil is provided with means for concentrating the lines of magnetic flux generated by the primary conductor on its side facing away from the primary conductor. These means contain flux-conducting elements in the form of strips and connection elements, which connect the ends thereof and consist of a material having high permeability and high electrical resistance, preferably a ferrite, especially a soft ferrite. The strips and connection elements are connected into a grid frame to be placed on the receiver coil by bonding or according to another method. 
         [0005]    Flux-conducting elements are manufactured from a material such as ferrite or the like by pressing and subsequent sintering of a powder prepared from this material. The flux-conducting elements obtained as a result are comparatively brittle, mechanically delicate and are poorly processable. In addition, the joining together of the flux-conducting elements into a grid frame is very labor-intensive. 
       SUMMARY OF THE INVENTION 
       [0006]    Based on this, the basic technical object of the present invention is to simplify the manufacture of the receiving unit and to overcome the drawbacks resulting from the brittleness of the flux-conducting elements. 
         [0007]    According to the invention, a receiving unit is provided with a receiver coil for the contactless transmission of electrical energy (power), wherein a plurality of flux-conducting elements, which are intended to concentrate lines of flux and which are formed of a material with high permeability compared to that of air, are associated with the receiver coil. The receiving unit has a basic body with depressions intended for receiving the flux-conducting elements. The flux-conducting elements are formed of a contiguous shaped part, which is arranged in the depressions, and which is integrated with the basic body into a completely prefabricated assembly unit. 
         [0008]    According to another aspect of the invention, a process is provided for manufacturing a receiving unit provided with a receiver coil for the contactless transmission of electric energy (power), wherein a plurality of flux-conducting elements, which are intended to concentrate the field intensity and are made of a material with high permeability compared to that of air, are associated with the receiver coil. The flux-conducting elements are formed in a basic body used as a shaping part. The basic body is provided with depressions intended to receive the flux-conducting elements. A liquid mixture is prepared from a casting resin and a powder of a material with high permeability, and the liquid mixture is then poured into the depressions to form the flux-conducting elements. 
         [0009]    The present invention offers the advantage that an assembly unit, which contains the flux-conducting elements and which can be prefabricated as a complete unit in a simple manner, optionally with or without an associated receiver coil, is obtained. Since the individual flux-conducting elements are connected to one another by a casting operation and are placed in a basic body, the difficulties that have hitherto been associated with flux-conducting elements made of ferrite or the like do not occur any longer. 
         [0010]    Further advantageous features of the present invention are discussed further below. The present invention will be explained in more detail below in connection with the attached drawings. 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 
         [0011]    In the drawings: 
           [0012]      FIG. 1  is a schematic view showing a partial section through a usual magnetic levitation vehicle in the area of a track provided with a long stator; 
           [0013]      FIG. 2  is a schematic perspective and greatly enlarged view of a part of a receiving unit; 
           [0014]      FIG. 3  is a schematic view showing a cross section through a receiver coil and the primary conductor according to  FIG. 2 ; 
           [0015]      FIG. 4  is a perspective view of a basic body according to the present invention, which can be used to manufacture a receiving unit; 
           [0016]      FIG. 5  is and enlarged sectional view taken along lines V-V from  FIG. 4 ; 
           [0017]      FIG. 6  is and enlarged sectional view taken along lines VI-VI from  FIG. 4 ; 
           [0018]      FIG. 7  is a sectional view through the basic body corresponding to  FIG. 6  after the receiver coil has been mounted and after a flux-conducting material has been poured in; and 
           [0019]      FIG. 8  is a schematic exploded perspective view showing the formation of an assembly unit according to the present invention, which can be used to manufacture the receiving unit. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    Referring to the drawings in particular,  FIG. 1  schematically shows a cross section through a magnetic levitation vehicle  1 , which is mounted such that it can travel on a track, which extends in the longitudinal direction of a line and contains carriers  2  manufactured from steel and/or concrete and track panels  3  mounted on these. The magnetic levitation vehicle  1  is driven by means of a long-stator motor, which has stator packages  4  fastened under the track panel  3  and follow each other in the longitudinal direction of said track panel. The energizing field proper of the long-stator motor is generated by at least one magnet array, which is provided with carrier magnets and has magnet poles facing grooves of the stator packages  4 , which said grooves are open downwardly in  FIG. 1 . Not only does the carrier magnet  5  provide the energizing field, but it also assumes the carrying and levitating function by maintaining a preset gap between the carrier magnet  5  and the stator packages  4  during the operation of the magnetic levitation vehicle  1 . The magnet array containing the carrier magnets  5  is otherwise accommodated in a magnetic back box  6 , which is fastened to the magnetic levitation vehicle  1  via laterally arranged frame straps. 
         [0021]    A primary conductor  7 , which is designed as a transmitting coil, preferably contains a line section  7   a ,  7   b  running back and forth and preferably extends over the entire length of the track, is provided along the track. The two line sections  7   a ,  7   b  are fastened to the carrier  2 , e.g., by means of a bracket  8  consisting of an insulator. The primary conductor  7  is connected, in addition, to a power source  9  of, e.g., 200 A, which is preferably a high-frequency power source and is shown only schematically. 
         [0022]    A receiving unit with a receiver coil  10  is mounted on the magnetic levitation vehicle  1 . This [receiver coil] is preferably designed such that it does not extend around the primary conductor  7  but is located opposite same at a short distance only. The receiver coil  10  preferably comprises a plurality of parallel conductors, which are arranged relative to the primary conductor  7  such that they are passed through by the lines of magnetic flux generated by this [primary conductor] or the line sections  7   a ,  7   b  and the current of approx. 200 A supplied by the primary conductor  7  can be uncoupled at the terminal ends thereof, not shown. The two terminal ends, not shown, of the receiver coil  10  are connected in the known manner, e.g., with a voltage transformer, which is part of a usual power supply unit, which supplies the magnetic levitation vehicle  1  with the electric power necessary for its operation. It is clear that corresponding primary conductors  7  are preferably installed on both sides of the carrier  2  when the magnetic levitation vehicles  1  are provided with carrier magnets  5  on both longitudinal sides and that as many receiving units are provided in the longitudinal direction of the magnetic levitation vehicles  1  as are necessary for the operation of the magnetic levitation vehicles  1  or desirable for reasons of redundancy. 
         [0023]    The receiver coil  10  is preferably manufactured as a prefabricated assembly unit together with the necessary contacting elements, e.g., plug-type connectors, and mounted on the magnetic back box  6 . It is especially advantageous to mount the receiver coil  10  at or in a shell-like cover element  11 , which is fastened to a rear side of the magnetic back box  6 , which said rear side faces the primary conductor  7 . 
         [0024]    The receiver coil  10  is preferably designed in the manner of a so-called layer winding. As is shown in  FIG. 2 , it contains a plurality of layers located in one plane. The individual layers are preferably made of a conductor with round or square cross section and have essentially straight first and second longitudinal sections  10   a ,  10   b , which extend in parallel to one another and along the magnet array, as well as end windings  10   c , which connect the ends thereof. The longitudinal sections  10   a ,  10   b  extend in parallel to the line sections  7   a ,  7   b  of the primary conductor  7  and are used to generate voltage. The first longitudinal sections  10   a  are associated with the line section  7   a  and the second longitudinal sections  10   b  are associated with line section  7   b  of the primary conductor  7  such that the line sections  7   a ,  7   b  are arranged approximately in the middle of the layer part formed by the associated longitudinal sections  10   a ,  10   b , as is shown especially in  FIG. 3 . By contrast, the conductors of the receiver coil  10  extend in the area of the end windings  10   c  essentially at right angles to the line sections  7   a  and  7   b , respectively. 
         [0025]    To increase the magnetic coupling between the primary conductor  7  and the receiver coil  10  and to avoid eddy current losses, the receiving unit has, furthermore, on the side of the receiver coil  10  facing away from the primary conductor  7 , a means for concentrating the field intensity generated by the primary conductor  7 , as it is schematically indicated by lines of magnetic flux  14   a ,  14   b  in  FIG. 3 . This means contains flux-conducting elements, which consist of a material with high permeability and high electrical resistivity. An especially preferred material for this purpose is ferrite, especially soft ferrite, which is, however, comparatively brittle, mechanically delicate and therefore poorly processable because it is manufactured from ferromagnetic powders by pressing and subsequent sintering. The flux-conducting elements are therefore composed of many, comparatively small strips of material and connection elements, which are connected to one another by bonding or according to other methods to form grid frames. 
         [0026]    A plurality of first material strips  15   a , which are arranged essentially at right angles to the line section  7   a  and in parallel to the winding plane formed by the longitudinal sections  10   a , are provided, e.g., on a side of the receiver coil  10  facing away from line section  7   a  in a construction likewise shown in  FIGS. 2 and 3 . A plurality of second material strips  15   b , which are preferably located in the same plane as the first material strips  15   a , are provided in a corresponding arrangement on a side of the receiver coil  10  facing away from line section  7   b . Both material strips  15   a ,  15   b  have a length that is somewhat greater than the height of the layer parts formed by the longitudinal sections  10   a ,  10   b , without overlapping with the ends facing each other. The individual material strips  15   a ,  15   b  are arranged in a grid-like pattern and in parallel to one another at preselected distances. 
         [0027]    The ends of the first material strips  15   a  are connected to one another by first connection elements  16   a , which are arranged essentially in parallel to line section  7   a . The ends of the second material strips  15   b  are correspondingly connected by second connection elements  16   b . Components designed in the manner of grid frames are formed as a result, which are fastened to the magnetic back box  6 . 
         [0028]    Both the material strips  15   a ,  15   b  and the connection elements  16   a  and  16   b  preferably consist of a ferrite. In addition, they are arranged close behind the longitudinal sections  10   a ,  10   b  and are arranged such that they bring about a concentration of the lines of flux  14   a  and  14   b  generated by the line sections  7   a ,  7   b , as this is schematically indicated in  FIG. 3 . It is assumed in  FIG. 3  that the current flows through line section  7   a  momentarily in a direction exiting from the drawing plane and it flows through line section  7   a  momentarily in a direction entering the drawing plane. Because of the high permeability of the material strips  15   a ,  15   b , the lines of flux  14   a ,  14   b  are closed directly behind the line sections  10   a ,  10   b , as is schematically indicated by arrows, as a result of which the magnetic coupling is greatly increased. Higher eddy current losses are at the same time prevented from developing because the material strips  15   a ,  15   b  and connection elements  16   a ,  16   b  magnetically shield the parts of the magnetic back box  6  located behind them because of their high permeability. Finally, the connection elements  16   a ,  16   b  shall bring about an extensively uniform distribution of the magnetic flux within the grid frame structure. The length of the material strips  15   a ,  15   b  and of the connection elements  16   a ,  16   b  is therefore preferably selected to be such that the largest possible number of lines of flux  14   a ,  14   b  are collected or concentrated. 
         [0029]    The connection elements  16   a ,  16   b  are preferably fastened on the sides of the material strips  15   a ,  15   b  facing the line sections  7   a ,  7   b . This leads to the advantage that they come to like essentially in the same plane as the longitudinal sections  10  [sic- 10   a ? Tr. Ed.],  10   b  of the receiver coil  10 , as is shown especially in  FIG. 3 . As a result, no additional space is required for them, especially if their thickness, which is sufficient from a magnetic point of view, is approximately equal to the thickness of the longitudinal sections  10   a ,  10   b.    
         [0030]    Receiving units of the type described are known from the document DE 10 2004 056 439 A1, which is made into the subject of the present disclosure by reference to avoid further repetitions. 
         [0031]    To simplify the manufacture of the grid frame comprising the strips  15   a ,  15   b  and connection elements  16   a ,  16   b , a basic body  18  ( FIG. 4 ) is used according to the present invention as a starting component, which is provided with depressions in the form of grooves or the like wherever the flux-conducting elements are to come to lie and can therefore be considered to be an organizing auxiliary means. Webs left in place between the depressions are designed such that their surfaces can also be used, at least partially, as contact surfaces for the receiver coil  10 . In addition, the flux-conducting elements do not consist of individual strips and connection elements, but a contiguous shaped part, which is arranged in the depressions and which is integrated with the basic body  18  into a completely prefabricated assembly unit. 
         [0032]    As is apparent from  FIGS. 4 through 6 , the basic body  18  is manufactured in the exemplary embodiment from an originally plane-parallel panel, which has, like the receiver coil  10 , an essentially rectangular outer contour and has accordingly two long longitudinal sides  18   a  arranged in parallel to one another and two short, likewise essentially parallel front sides  18   b  arranged at right angles thereto. In addition, the basic body  18  is divided by a middle web  19  extending in parallel to the longitudinal sides  18   a  into two halves, which are essentially mirror-symmetrical in relation to this. 
         [0033]    To form the strips  15   a ,  15   b  ( FIG. 2 ), each half of the basic body  18  is provided, from its broad side that is the upper broad side in  FIGS. 4 through 6 , with a plurality of first depressions  20 , whose lower limitations or bottoms are indicated by broken lines in  FIGS. 6 and 7 . The depressions  20  extend into a first plane  21  of the basic body  18  and are arranged at right angles to the longitudinal sides  18   a  and to the middle web  19 , on the one hand, and in parallel to one another, on the other hand. The number and size of these depressions  20  correspond to the number and size of the strips  15   a  and  15   b  to be prepared. 
         [0034]    Webs  22  left in place between the depressions  20  are provided according to  FIGS. 5 and 6 , at their ends adjoining the longitudinal sides  18   a  and the middle web  19 , with second depressions  23 , which likewise extend into the first plane  21  and are thus connected to the first depressions  20 . 
         [0035]    In one exemplary embodiment, which is considered to be the best so far and is shown in  FIGS. 4 through 7 , the height of the parts  22   a  of the webs  22  ( FIG. 6 ) that remain after the second depressions  23  have been formed and face the longitudinal sides  18   a  is reduced, so that these parts reach only a second plane  24 , which has a distance that corresponds to the thickness of the strips  15   a  and  15   b  to be prepared from the first plane  21 . Third depressions  25 , which are used to mount the longitudinal sections  10   a ,  10   b  of the receiver coil  10 , are formed as a result. Depressions  25  extend at right angles to the longitudinal sides  18   a  of the basic body  18  from the second depressions  23  to the steps  22   b  of the webs  22  and have a length in the direction of extension that corresponds to the width of the receiver coil  10  to be inserted, whose longitudinal sections  10   a ,  10   b  can be seen in  FIG. 7 . 
         [0036]    The surfaces of parts  22   c  of the webs  22 , whose height is reduced, are located in a third plane  26  of the basic body  18 . The surfaces of an edge section  27  of the basic body  18 , which extends all around, as well as of the middle web  19  are also located in this plane  26 , which has a distance from the second plane  24  that corresponds essentially to the thickness of the receiver coil  10 . 
         [0037]    The basic body  18  is provided with additional depressions  28  ( FIG. 4 ) extending into the second plane  24  in an area each adjoining the front sides  18   b . The size of these depressions is selected to be such that they can receive the end windings  10   c  ( FIG. 2 ) of the receiver coil  10 . In addition, the height of the different layers of the receiver coil  10  is selected to be such that after it has been placed on the upper surfaces or bottoms of the depressions  25  and  28 , it closes flush with the third plane  26 , as is shown in  FIG. 7 . 
         [0038]    The receiving unit is advantageously manufactured in the manner shown in FIG.  8  as follows: 
         [0039]    The basic body  18  is first provided with the depressions  20 ,  23 ,  25  and  28  and webs  22  shown in  FIGS. 4 through 6  by subjecting a plane-parallel panel, e.g., to a machining process, especially various milling steps. The depressions  25  and  28  then form a space intended for receiving the receiver coil  10 . This space is dimensioned such that, on the one hand, the receiver coil  10  comes into contact with step  22   b  with its inner contour  10   d  when it is inserted into the basic body  18  ( FIG. 7 ) and is hereby positioned in the transverse direction of the basic body  18  and, on the other hand, it abuts against the free ends of the middle web  19  and is thus oriented in the longitudinal direction of the basic body  18 . This state is shown in the lowermost picture in  FIG. 8 . In other words, steps  22   b  and the ends of the middle web  19  form stop and positioning means for exactly positioning the receiver coil  10  in the basic body  18 . 
         [0040]    The respective last webs designated by reference number  22   a  in  FIG. 4  are designed without depressions  23  in the two halves of the basic body  18  in the exemplary embodiment, so that they extend to the third plane  26  in the area of the depressions  23  and have only the depressions  25  intended for inserting the receiver coil  10 . 
         [0041]    The receiver coil  10  is now inserted into the basic body  18  in a subsequent process step, as this is shown in  FIGS. 7 and 8 . The receiver coil  10  is now in contact with the steps  22   b , so that the depressions  23  remain free. 
         [0042]    A liquid mixture, which contains a curable casting resin and a powder, which consists of a material having high permeability, is prepared in another process step. A powder of ferrite, preferably a soft ferrite, is used for this, in particular. This mixture may, of course, also have been prepared already before the manufacture of the basic body  18  and/or before the insertion of the receiver coil  10  in this. 
         [0043]    The finished mixture, which preferably contains a multicomponent casting resin provided with a curing agent, is now poured into the depressions  23  left free by the receiver coil  10  by means of pouring nozzles, not shown. As an alternative, a pouring spout, which passes over the length of the depressions  23 , may be used for this as well. The casting resin penetrates during the casting operation not only into the depressions  23 , but also into the depressions  20 , which extend between these and are partly under the receiver coil  10 , and fills these completely. The basic body  18  is thus used as a casting mold. The casting resin is prevented from running out into the depressions  28  by raised webs  22   a  at the lateral ends of the web rows. 
         [0044]    The casting operation is concluded when the level of casting resin has reached the third plane  26  ( FIG. 7 ). As a result, the casting resin can rise up to level  26  in the areas located between the parts  22   c  of the webs  22 , as this is indicated in  FIG. 3  by a broken line  29 . However, this does not compromise the function of the strips  15   a ,  15   b  as flux-conducting elements. 
         [0045]    One advantage of the process described is that a shaped part of the type of a grid form is formed, which contains the strips  15   a ,  15   b  and connection elements  16   a ,  16   b  shown in  FIGS. 2 and 3  with the difference that these are manufactured in one piece and form a one-piece, contiguous grid frame, which is arranged recessed in the basic body  18 . Special measures for connecting the strips  15   a ,  15   b  and connection elements  16   a ,  16   b  are therefore unnecessary. Furthermore, it is advantageous that the receiver coil  10  is also already inserted into the basic body  18  and is firmly embedded in same by the casting operation. The basic body  18 , receiver coil  10  and flux-conducting elements  15   a ,  15   b ,  16   a ,  16   b  therefore form a receiving and assembly unit, which is completely preassembled or can be completely preassembled and which is connected as a whole to the cover  11  ( FIG. 1 ) of the magnetic back box  6  or can be integrated in same as a whole. 
         [0046]    It may be advantageous when the casting process described on the basis of  FIGS. 5 through 8  is used to design the flux-conducting elements  15   a ,  15   b  ( FIG. 2 ) as panels passing over the length of the receiver coil  10 . The webs  22  ( FIGS. 5 through 7 ) may be eliminated in this case altogether and the depressions may be designed as continuous depressions in the longitudinal direction of the basic body  18 . For example, the entire lower space of the basic body  18  up to level  24  ( FIG. 6 ) would then be filled with the casting resin mixture, the receiver coil would then be inserted, and the space occupied by the flux-conducting elements  16   a  and  16   b  in  FIG. 7  would finally be filled with the casting resin mixture. 
         [0047]    The basic body  18  is preferably prepared from a plastic, especially a foam, e.g., polyurethane, and especially advantageously from a foam with damping action. However, it is also possible, as an alternative to machining, to prepare the basic body  18  as a whole by casting, foaming or pressing using a corresponding die. 
         [0048]    The present invention is not limited to the exemplary embodiment described, which can be varied in many different ways. This applies, in particular, to the grid frame-like structure of the flux-conducting elements shown in  FIGS. 2 and 3 , because these may also be arranged in other advantageous patterns and can be made larger or smaller than described. It is, furthermore, possible if necessary to provide the basic body  18  only with the flux-conducting elements  15   a ,  15   b ,  16   a ,  16   b  and to fill the depressions  25  during the casting of the flux-conducting elements with a displacement body, which is designed corresponding to the receiver coil  10  in order to prevent hereby the casting resin from entering the depressions  25 . The same procedure may be followed when the basic body  18  is manufactured by casting, pressing or the like in order to keep the depressions  25  and  28  free for the receiver coil  10 . The receiver coil  10  would then be inserted into the assembly unit formed from the basic body  18  and the flux-conducting elements  15   a ,  15   b ,  16   a ,  16   b . The complete receiving unit would be of a two-part design in this case. Furthermore, it is clear that the receiver coil  10  is provided with connection contacts, not shown, at suitable points and the depressions  28  may be absent altogether, especially when it is desirable to bend off the end windings  10   c  to the rear analogously to DE 10 2004 056 439 A1. Finally, it is obvious that the different features may also be used in combinations other than those described and shown. 
         [0049]    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.