Abstract:
An electrical machine includes a basic bed having a opposite axial end sides and slots, wherein the slots an the end sides have each a slot end opening. A winding system has electrical conductors which are accommodated in the slots wherein the electrical conductors extend out on one of the end sides of at least one of the slot end openings. The electrical conductors are hereby laid within a bridging region extending in a circumferential direction on the at least one end side and are inserted into at least one other one of the slot end openings. Arranged on the at least one end side in the bridging region is a first guide element for guiding the electrical conductors of a first subwinding of the windings stem. An end late is arranged on the at least one end side and has at least one axially protruding separating element with the first guide element having a base bearing a against the separating element.

Description:
BACKGROUND OF THE INVENTION 
   The invention relates to an electrical machine with an axis of rotation and a basic body, which contains two axial end sides and slots for accommodating electrical conductors of a winding system. 
   Such an electrical machine is in the form of an electric motor, for example. In order to manufacture the winding system, the basic body, which is in particular in the form of a stator or a stator laminate stack, has recently been wound with a so-called needle winder, a winding nozzle of the needle winder laying an electrical conductor in the interior of a stator bore into one of the slots and progressing in the axial direction, i.e. in the direction of the axis of rotation. The winding nozzle (=needle) is first moved a bit further outwards in the axial direction at the end side. Then, the stator laminate stack is rotated about the axis of rotation until the slot end opening of that slot appears at the level of the winding nozzle at which the electrical conductor is guided back in the opposite direction within the stator bore. The process takes place in mirror-image fashion on the opposite end side. This is repeated corresponding to the desired turns number, so that winding heads form at the two end sides. 
   The winding system can comprise a plurality of subwindings, which are introduced into the stator laminate stack successively with the described method. In this case, the deflection path length at the end sides when the subwindings are subsequently introduced is greater than when the subwindings are first produced. As a result, the mean coil lengths of the individual subwindings differ from one another. In addition, the amount of material used when the subwindings are introduced subsequently increases, as a result of which the individual subwindings may also have differences as regards their electrical resistance. 
   SUMMARY OF THE INVENTION 
   The object of the invention therefore consists in specifying an electrical machine of the type mentioned at the outset which has a high-quality winding system. 
   This object is achieved according to the invention by an electrical machine in which
     a) the slots on the end sides each have a slot end opening,   b) the electrical conductors on one of the end sides,
       b1) are passed out of at least one of the slot end openings,   b2) are laid within a bridging region running in the circumferential direction on the end side, and   b3) are inserted into at least one other one of the slot end openings,   
       c) a first guide element for guiding the electrical conductors of a first subwinding of the winding system is arranged on the end side in the bridging region, and   d) an end plate with at least one axially protruding separating element is arranged on the end side and the first guide element bears against the separating element with a base.   

   The guide element used according to the invention permits very uniform and controlled winding even at the end side. In addition, effective utilization of space primarily also in the radial direction is achieved, so that a shorter axial extent in comparison with the known electrical machines also results. 
   The use of the guide element makes it possible to arrange the individual layers of the electrical conductors in a controlled manner, so that the winding head at the end side can be configured in a defined manner. In particular, successively produced subwindings with substantially identical turn lengths and subsequently identical electrical resistances can also be realized in this way. 
   Overall, the use according to the invention of the guide element therefore results in a very precise and high-quality winding. In particular, a reduction in the mean coil length is achieved in comparison with a winding without the guide element. This results in an improvement in the electrical operational data of the electrical machine with reduced use of material at the same time. 
   As a result of the first guide element bearing against the end side of the end plate, the guide element is secured in position and, as a consequence of this, a high degree of manufacturing accuracy is achieved. In particular, the electrical insulation between the electrical conductors of adjacent subwindings or between the electrical conductors and the basic body is ensured owing to the guide element which is fixed in position. 
   A favorable variant is one in which an end plate with at least one axially protruding separating element is arranged on the end side, and the first guide element bears with a base against the separating element. As a result, the guide element is secured in position and, as a consequence of this, a high degree of manufacturing accuracy is achieved. In particular, the electrical insulation between the electrical conductors of adjacent subwindings or between the electrical conductors and the basic body is ensured owing to the guide element which is fixed in position. 
   In further preferred configurations, the first guide element has a U or an L profile. As a result, particularly effective guidance of the electrical conductors is achieved. 
   Preferably, the first guide element can furthermore run in the circumferential direction and have the shape of a circular arc segment. In this case, it is matched particularly well to the generally cylindrical geometry of the basic body and to the bridging region, which is likewise in the form of a circular arc segment. 
   Furthermore, it is advantageous if a further guide element for guiding the electrical conductors of a further subwinding of the winding system is arranged axially adjacent to the first guide element. In this way, a plurality of subwindings can also be controlled and manufactured precisely and arranged in particular at the end sides in a very space-saving manner next to one another. 
   Preferably, the guide elements are then in addition designed to be stackable, so that a tightly adjacent and therefore space-saving arrangement is possible. 
   It is furthermore preferred that the first guide element has a limb and a base, which abut one another at a bending edge, and a cutout runs along the bending edge in an outer region facing away from the electrical conductors. A base of a further, in particular L-profiled guide element can be inserted into the cutout and thereby fixed in position. This favorable insertion one inside the other in addition also reduces the axial extent. 
   Another favorable configuration is characterized by the fact that the first guide element is designed to be electrically insulating. This increases the electrical safety and also the functional reliability of the electrical machine overall. In particular, the electrical insulation with respect to the basic body is also ensured when no electrically insulating end plate is used. 
   It is furthermore preferred that the first guide element is made from a plastic material. It can then be produced easily, for example by means of a conventional injection-molding process. In addition, many plastic materials meet the requirements for the electrical insulation capability. 
   Further features, advantages and details of the invention are given in the description below relating to exemplary embodiments with reference to the drawing, in which: 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  shows an exemplary embodiment of a basic body to be wound of an electrical machine with end plates arranged at the end sides, in a plan view, 
       FIG. 2  shows the basic body shown in  FIG. 1  in a cross-sectional illustration, 
       FIGS. 3 and 4  show an exemplary embodiment of a guide element and an auxiliary winding body which is positioned on the end plate shown in  FIG. 1  during a winding process, 
       FIG. 5  shows the auxiliary winding body, which has fastening apertures on its underside, as shown in  FIGS. 3 and 4 , 
       FIG. 6  shows an exemplary embodiment of a further guide element, which is used in conjunction with the auxiliary winding body shown in  FIGS. 3 to 5 , 
       FIG. 7  shows the guide element shown in  FIG. 6  in the wound state, 
       FIG. 8  shows an exemplary embodiment of two already wound guide elements shown in  FIG. 6  and a third guide element as shown in  FIG. 6  which is yet to be wound as well as an auxiliary winding body, which is positioned on the end plate shown in  FIG. 1  during a third subwinding process, 
       FIG. 9  shows an exemplary embodiment of an auxiliary winding body with a fastening protrusion on its underside, and 
       FIGS. 10 to 12  show exemplary embodiments of auxiliary winding bodies with different circular-arc covering. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Mutually corresponding parts are provided with the same reference symbols in  FIGS. 1 to 12 . 
     FIG. 1  illustrates an exemplary embodiment of an electrical machine  1  in the form of an electric motor with a basic body  2  to be wound and a rotor  4 , which is mounted such that it is capable of rotating about an axis of rotation  3 . The basic body  2  belongs to a stator of the electrical machine  1  and is in the form of a stator laminate stack. It has axial end sides  5  and  6 , on which in each case one electrically insulating end plate  7  and  8 , respectively, is arranged. The end plates  7  and  8  have axially protruding separating webs  9 , which are arranged so as to be uniformly distributed in the circumferential direction. 
   As shown in the cross-sectional illustration in  FIG. 2 , the basic body  2  has a stator inner bore, in which the rotor  4 , which is not illustrated in  FIG. 2 , is placed. Axially running slots  10 , which are distributed uniformly over the circumference, are provided in the basic body  2  adjacent to an inner wall of this stator inner bore. If appropriate, the slot profile can have a slight incline deviating from the precisely axial direction. Slot webs  11  are arranged between the slots  10 . 
   The insulating end plates  7  and  8  are arranged on the end sides  5  and  6 , respectively, in such a way that their separating webs  9  are aligned with the slot webs  11 . The number of separating webs  9  and slot webs  11  is the same. 
   Electrical conductors  12  of an electrical winding system  13  to be introduced into the basic body  2  are placed within the slots  10 . In the exemplary embodiment shown in  FIG. 2 , the basic body is shown in a partially wound state. Electrical conductors  12  are arranged only in some of the slots  10 . At the end sides  5  and  6 , the slots  10  have slot end openings  14 , from which the electrical conductors  12  protrude in order to be deflected outside the basic body  2  at the end sides  5  and  6  and be guided to another one of the slots  10 . This deflection and guidance of the electrical conductors  12  takes place in the exemplary embodiment shown in  FIGS. 1 and 2  by means of the insulating end plates  7  and  8 . In  FIG. 2 , this deflection and conductor guidance is indicated schematically. 
   The end plates  7  and  8  can be used universally. They can be used to realize winding systems  13  for various pole numbers. When winding the basic body  2  and also the end plates  7  and  8  with the electrical conductors  12 , high tensile stresses and a high degree of friction between the separating webs  9  and the electrical conductors  12  can arise. 
   This may firstly lead to bending of and/or damage to the separating webs and secondly to damage to the electrical conductors, for example their electrical insulation. 
   In order to prevent these disadvantageous effects during the winding process, the separating webs  9  are covered in a bridging region  15  by means of an auxiliary winding body  16  shown in  FIGS. 3 to 6  and are therefore protected. The auxiliary winding body  16  is in the form of a winding shoe and has the shape of a circular arc segment. Its outer wall  17  is smooth and has rounded-off outer wall edges  18 . It has a rounded-off surface contour and, in the exemplary embodiment, is produced from aluminum. 
   When winding the basic body  2 , the deflection and guidance of the electrical conductors  12  no longer takes place by means of the separating webs  9  of the end plates  7  or  8 , but by means of the auxiliary winding body  16 . In order to produce a subwinding with a plurality of turns, in each case one auxiliary winding body  16  is arranged on one of the two end sides  5  and  6  in such a way that it covers the slot end openings  14  which are not to be wound during this subwinding process within the bridging region  15  running in the circumferential direction. The electrical conductor  12  is inserted into one of the slots  10 , whose slot end opening  14  lies on a side of the bridging region  15  which points in the circumferential direction, and is guided out through the associated uncovered slot end opening  14 . Then, it is deflected at the relevant end side  5  or  6  by means of the auxiliary winding body  16  and guided to a further uncovered one of the slot end openings  14 , which lies on the other side of the bridging region  15  which points in the circumferential direction, in order to be inserted into the associated slot  10  there and to be guided to the other end side  6  or  5 . There, the process is repeated in mirror-image fashion, so that a complete turn is produced. Depending on the turns number envisaged, this process described for one turn is repeated. Once this subwinding process has come to an end, the auxiliary winding bodies  16  which have been arranged in auxiliary fashion on both end sides  5  and  6 , are removed again. The described winding operation can be carried out in particular automatically by means of a needle winder. 
   Fastening apertures  20  are provided on an underside  19  of the auxiliary winding body  16  and reach into the auxiliary winding body  16  starting from the underside  19 . The fastening apertures  20  are used for accommodating the separating webs  9 . Even on its two side cheeks pointing in the circumferential direction, the auxiliary winding body  16  has in each case one lateral aperture  21 , by means of which in each case one of the two separating webs  9 , which are arranged at the edge of the bridging region  15 , is held and protected. 
   The outer wall  17  has a projection  22 , which reaches beyond the underside  19  and does not extend over the entire circular arc segment in the circumferential direction, which circular arc segment is covered by the remaining auxiliary winding body  16 . The projection  22  acts in the same way as the smooth outer wall  17  for targeted guidance of the electrical conductors  12 . The electrical conductor  12  which is just to be introduced is guided, in combination with the deflection in the outer region of the basic body  2 , over the smooth outer wall  17  of the auxiliary winding body  16  and, as indicated in  FIGS. 4 and 6  by the directional arrows, is drawn downwards. The projection  22 , which is provided at the end in this movement direction, allows the electrical conductor  12  to slide into a U-profiled guide element  23  ( FIGS. 3 and 4 ) or L-profiled guide element  24  ( FIG. 6 ), which guide element  23  or  24  is arranged between the auxiliary winding body  16  and the end plate  7 , in a targeted manner. The U-profiled guide element  23  has two U limbs  23   a  and  23   b  and a U base  23   c . The L-profiled guide element  24  has an L limb  24   a  and an L base  24   b . Both guide elements  23  and  24  are also designed to be in the form of circular arcs. In the state shown in  FIGS. 4 and 6 , in each case one turn of the electrical conductor  12  is already located in the respectively associated guide element  23  or  24 , while the next turn is being produced, the electrical conductor  12  being guided along the smooth outer wall  17  of the auxiliary winding body  16 . 
   A bearing face  25  for the guide element  23  or  24  is provided adjacent to the projection  22  on the underside  19  of the auxiliary winding body  16 . By means of the bearing face  25 , the guide element  23  and  24  is fixed in its position in such a way that it does not experience any undesirable shift in position during the winding process. The guide elements  23  and  24  have an electrically insulating function which, owing to this advantageous positional fixing, is ensured to the full extent after the winding process. With other known types of insulation for subwindings of the winding system  13  a shift in the insulation can take place under the influence of tensile stresses during the winding process and therefore an impairment of the insulating properties may result. This disadvantage is circumvented by the positional fixing of the guide element  23  or  24 . 
   The auxiliary winding body  16  permits a largely uniform winding of the guide elements  23  and  24  with the individual turns of the electrical conductor  12 . The dimensions of a subwinding  26  produced in this way and shown in  FIG. 7  can be preset in advance via a corresponding dimensioning of the auxiliary winding body  16  and the guide element  23  or  24 . In particular, effective utilization of space primarily in the radial direction is achieved thereby. In other winding processes which operate without the auxiliary winding body  16  and the guide elements  23  or  24 , the resulting subwindings extend more in the axial and less in the radial direction. This results in an axially longer overall design. In contrast, the electrical machine  1  which is wound with the favorable winding process and using the favorable guide elements  23  and  24  is characterized by clearly improved utilization of space and therefore a shorter axial extent. The favorable winding process and the favorable guide elements  23  and  24  can in this case either be used in combination or else as an individual measure, i.e. either the winding process or the guide elements  23  and  24 . 
   In addition, the thus resulting winding system  13  bears very tightly against the basic body  2  even in the region of the end sides  5  and  6 , in which winding heads (not illustrated in any more detail) are formed, with the result that good thermal coupling is provided. This has a favorable effect on the dissipation of the heat produced in the electrical conductors  12  in the region of the winding heads, via the stator laminate stack of the basic body  2 . 
   As shown in the illustration in  FIG. 7 , the L-profiled guide element  24  has a cutout  27  in the outer region of the bending edge between the L limb  24   a  and the L base  24   b , into which cutout an L base  28   b  of a further L-profiled guide element  28  can engage. Thus, a positionally fixed construction of a plurality of guide elements  24  and  28  which is stacked in the axial direction can be realized. By way of example,  FIG. 8  shows an embodiment with three guide elements  24 ,  28  and  29  stacked adjacent to one another. In this case, the L bases  28   b  and  29   b  of the guide elements  28  and  29 , respectively, are fixed in the cutout  27  of the guide element  24  and  28 , respectively, lying therebeneath and the L base  24   b  of the lowermost guide element  24  is fixed in a similarly designed cutout  30  of the end plate  7 . 
   The exemplary embodiment shown in  FIG. 8  shows a state in which the guide elements  24  and  28  have already been wound completely with the subwinding  26  or with a subwinding  31 . In contrast, the third guide element  29  is just being wound with the electrical conductors  12  of a further subwinding  32 . 
   The guidance of the electrical conductors  12  takes place by means of an auxiliary winding body  33 , which is positioned onto the separating webs  9  of the end plate  7 . In contrast to the auxiliary winding body  16 , however, its engage-over width is matched to the longer dimension in the axial direction of the stack construction comprising the three guide elements  24 ,  28  and  29 . In addition, the bearing face  25  for the third guide element  29  is formed by means of a depression  34  on the underside  19  of the auxiliary winding body  33 . This results in very effective positional fixing of the third guide element  29 . 
     FIG. 9  illustrates a further exemplary embodiment of an auxiliary winding body  35 . In contrast to the auxiliary winding bodies  16  and  33 , the auxiliary winding body  35  has, on its underside  19 , instead of the fastening apertures  20  at least one fastening protrusion  36 , which extends axially downwards away from the underside  19  and is used for engaging in one of the slots  10  of the basic body  2 . The auxiliary winding body  35  is therefore plugged in directly at the basic body  2  for the duration of the winding process. An end plate  7  or  8  as in the above-described exemplary embodiments is not required. 
     FIGS. 10 to 12  show further exemplary embodiments of auxiliary winding bodies  37 ,  38  and  39 , respectively, which are used in conjunction with the end plate  7  or  8  during the winding process. They differ from one another in terms of the size of the respective covered circular arc segment. The auxiliary winding bodies  37  to  39  are each intended for different embodiments of the electrical machine  1 . In particular, winding systems  13  with various pole numbers can therefore be realized. The auxiliary winding bodies  37  to  39  each have a different covering region  40 ,  41  and  42 , respectively. In each case a different number of slot end openings  14  is covered and bridged for the purpose of guiding the electrical conductor  12 . The guide elements which are also used but are not shown in  FIGS. 10 to 12  cover the same circular arc segment as the auxiliary winding bodies  37  to  39 . 
   Owing to the use of the auxiliary winding bodies  16 ,  33 ,  35 ,  37 ,  38  or  39  and in particular also the guide elements  23 ,  24 ,  28  or  29 , precise shaping of the winding system  13  in the region of the end sides  5  and  6 , i.e. precise shaping of the winding heads, is achieved. In particular, it is possible in this way for winding heads with a comparatively large radial and short axial dimension to be realized. In particular, the radial space up to the outer circumference of the basic body  2  is virtually completely used. Owing to this good utilization of space in the radial direction, the shortening in the axial direction results, with the result that other components of the electrical machine  1  such as the housing and/or the mounting plates, for example, can also be designed to be axially shortened. This results in a reduction in the use of materials. In addition, the electrical operational data of the electrical machine are improved. For example, the efficiency is increased as a result of lower copper losses. 
   In addition, the use of the auxiliary winding bodies  16 ,  33 ,  35 ,  37 ,  38  or  39  and in particular also of the guide elements  23 ,  24 ,  28  or  29  permits a comparable configuration of the various subwindings  26 ,  31  and  32  of the winding system  13 . In particular, these subwindings  26 ,  31  and  32  have a virtually identical or at least very similar mean coil length and a substantially identical electrical resistance.