Abstract:
The invention relates to a method and device for producing an electric machine, an electric machine with a commutator, having commutator hooks for fixing electric wire windings with solder arranged between the commutator hooks and the wire winding and two electrodes arranged adjacent to each other which are pressed against the commutator hooks. An electric current is passed through the commutator hooks by means of electrodes such that the solder melts and forms a connection to the wire winding.

Description:
TECHNICAL FIELD 
     The invention is based on a procedure and a device for producing an electric machine according to the type of the independent claims. 
     BACKGROUND 
     Due to G 89 02 562.8 an ultra sound welding device for fixing wire ends of wire windings at terminal lugs of a commutator became known. Thereby a sonotrode of the ultra sound welding device presses the wire against a terminal lug of the commutator. Thereby ultra sound energy is directly inserted into the wire, which warms up so much that it creates a welding connection with the terminal lug of the commutator. Such an ultra welding procedure has the disadvantage that the material of the wire and the terminal lug are selectively melted in order to create a strong connection. Such a strong heat input can cause a damaging of the components that are adjoining the terminal lug. 
     SUMMARY 
     In contrast the procedure and the device according to the invention with the characteristics of the independent claims has the advantage that a good mechanic and electric connection between the wire winding and the commutator is created by inserting the solder between the wire winding and the commutator hooks, without melting the core material of the wire winding and the commutator hook. Thereby components that are for example alloyed to the commutator hook or adjoining plastic parts are protected from excessive heating. The current, which flow through the commutator hook over the electrodes, can be measured in such a way that the solder is melted for creating a solder connection between the wire winding and the commutator without creating a welding connection between the wire winding and the commutator. 
     Due to the measures that are listed in the dependent claims advantageous improvements and upgrades of the characteristics that are listed in the independent claims are possible. In order to create a mechanically strong connection between the wire winding and the commutator the wire is favorably arranged inside of the bending area, at which the commutator hook is formed at a corresponding counter surface. Thereby the free end of the commutator hook is pressed against the counter surface so that the wire windings are firmly embraced by the commutator hooks. 
     The free shank of the commutator hook can advantageously be pressed against the counter surface by the electrodes, after the wire windings have been inserted in the u-formed or v-formed opened commutator hook. During this first press phase the electrodes are not yet energized in order to minimize the heat input into the commutator hook. 
     By the subsequent aimed energizing of the electrodes heat can be inserted into the commutator hook in such a big amount that the isolation of the wire winding is removed, the solder melts and the free shank of the commutator is formed warmly under the pressure of the electrodes. 
     It is very favorable to press the electrodes still against the commutator hooks after creating the solder connection without a current supply in order to allow an effective heat discharge by the electrodes. 
     Expediently the electrodes abut on the commutator hook in a distance of ca. 0.5 to 3 mm in order to prevent a short circuit between the electrodes during the connecting procedure according to the invention. By covering the electrodes as far as possible with the commutator hook it can be pressed on the one hand with its entire surface against the counter surface and on the other hand energy can be transported fast into the commutator hook and out of it. Silver or tin qualify best as solder material or an alloying with these materials, which melts or alloy approximately between 200 and 300° C.—preferably between 210 and 240° C. Thereby a damaging of the components that adjoin the counter surface can be prevented. 
     The solder can be arranged at low-cost by layering the commutator hook together with the counter surface on the entire surface with the solder. The solder can be then melted selectively in the area, in which the commutator hook lies after the pressing against the counter surface, by which electrode current can be melted. 
     The commutator hook with the counter surface is advantageously made of copper-bearing material, which has a significantly higher melting point than the solder. 
     The procedure according to the invention is especially applicable for creating a flat-commutator, at which the counter surface provides a radial extension, which is connected with a carbon-running surface for the electric sliding contacts. The connection layer between the radial extension and the carbon-running surface can be effectively protected by the producing procedure according to the invention from an overheating. 
     When implementing the procedure according to the invention the electrode device provides for example two adjusting cylinders, with which the two electrodes can be linearly independent from each other. Thereby the two electrodes can be pressed on the commutator hook with a small distance from each other whereby the pressing forces or the adjusting ways of both electrodes can be adjusted differently. 
     By the producing procedure according to the invention an electric machine can be produced, at which the wire wiring is connected with the commutator and the counter surface by a solder connection. Thereby a bead and/or a heel is created at the radial outer circumferential surface of the commutator hook, which runs transversely to the armature wave and which has been formed by the adjoining electrodes that are pressed against the commutator hook. 
     According to the invention at the electric machine one or two or three or several wire windings can be connected with the commutator hook by the solder connection. The wire windings connect the commutator hook with the armature lamellae stack, on which the wire windings are coiled especially for creating a rotor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments of the invention are shown in the drawings and further explained in the subsequent description. 
         FIG. 1  shows schematically a cut through an electrode arrangement according to the invention with a commutator, 
         FIG. 2  is a variation of the schematically shown producing procedure, and 
         FIG. 3  is a section of an electric machine that has been produced according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a commutator  12  as part of the electric machine  10 , which is fixed on a rotor spindle  16  by a commutator hook  14 . The commutator  12  is in  FIG. 1  construed as drum commutator  18  or as flat commutator  19 , at whose outer circumference several commutator hooks are arranged. The commutator hook  20  provides a free shank  22 , which is connected over a bending area  24  with the counter surface  26  of the commutator hook  20 . For winding up an electric wire winding  28  onto the electric machine  10  the commutator hook  20  is designed in a V-form or a U-form, so that the wire windings  28  can be simply inserted into the open lug  30  of the commutator hook  20 . The counter surface  26  and the inside  32  of the free end  22  are layered with a solder  34  even before the wire winding  28  is inserted into the open lug  30 . In order to connect the wire winding  28  electrically and mechanically with the commutator  12  after finishing the winding process of the electric machine  10 , a solder connection is created with the aid of two electrodes  40 . Therefore the two electrodes  40  are pressed against the free shank  22  of the commutator hook  20  with a distance  42  to each other. In the embodiment in  FIG. 1  the two electrodes  40  are pressed parallel to each other against the commutator hook  20 , whereby the distance  42  amounts for example to 0.5 to 3 mm. During the pressing of the electrodes  40 —approximately vertically to the counter surface  26 —the free shank  22  is pressed against the counter surface  26 . During this procedure step the electrodes  40  are not yet energized so that an reforming of the commutator hook  20  is a cold reforming Subsequently the two electrodes  40  are energized so that a current flows over the electrodes  40  through the commutator hook  20 . Thereby the commutator hook  20  is warmed up so strong that an isolation layer  29  on the wire windings  29  evaporates and that solder  34  between the free shank  22  and the counter surface  26  melts. In this state the commutator hook  20  is so warm that it can be easily reformed by the pressing pressure  44  of the electrodes  40  and therefore it is simply minted. 
     Such a procedure step is for example shown in  FIG. 2 , at which the left electrode  40  is adjusted a little stronger against the counter surface  26  than the right electrode  40 . Thereby a heel  46  is formed at the outer circumferential surface  48  of the commutator hook  20  in the area of the free shank  22 . Due to the pressing pressure of the two electrodes  40  a bead  50  is created, which spans in circumferential direction  68  and which provides a width  52 , which corresponds approximately with the distance  42  between the electrodes  40 . The melted solder  34  creates now a tight fit between the wire windings  28  and the commutator hook  20  or the counter surface  26 . Thereby a mechanically stabile connection on the one hand and an electrically well conducting contact between the wire windings  28  and the commutator  12  on the other hand is created. In the embodiment of  FIG. 2  the left electrode  40  for example is not adjusted parallel to the right electrode  40 , but under an angle  53 . At this solution more installation space for the electrode connections or a not shown adjusting device of the electrodes  40  is available between the two electrodes  40 . The solder  34  is arranged in this embodiment only in the area of the commutator hook  20  and does not span over the entire axial area of the counter surface  26 . The counter surface  26  is here connected with a radial extension  54 , which is designed as carrier  56  for a carbon running surface  58 . The commutator  12  is hereby construed as flat commutator  19  so that the carbon running surfaces  58  are connected with a heat sensitive connection layer  82  with radial extension  54  and that it is surrounded at the outer circumference  48  with a plastic layer  64 . The electrodes  40  are still pressed against the commutator hook  20  for a certain time after turning off the filament current in order to discharge the heat from the commutator  12 . The wire windings  28  connect the commutator  12  with an armature lamellae stack  66 , on which the wire windings  28  are winded up. Depending on the configuration of the electric machine  10  a different amount of winding strands are arranged on the armature lamellae stack  66 , which are connected with a different amount of commutator hooks  20 . Therefore the amount of individual wire winding  28 , which are soldered with the individual commutator hooks  20 , wary correspondingly so that for example one or two or three or several wire windings  28  are lead through the lug  30 . The amount of the commutator hooks  20  corresponds with the amount of different commutator lamellae, whereby all commutator hooks  20  are connected with the wire winding  28  after each other or at least almost simultaneously according to the invention. 
       FIG. 3  shows an extract of a collector  12 , which has been connected with a wire winding  28  by the producing procedure according to the invention. The free shank  22  lies thereby at the counter surface  26  and is connected with it by the solder  34 . The solder  34  also creates a mechanic and electric connection between the wire winding  28  and the counter surface  26 , as well as the inside  32  of the free shank  22 . At the outer circumference  48  of the commutator hook  20  the bead  50  is created, whose width  52  is equivalent to a distance  42 , with which the two electrodes  40  have been pressed against the commutator hook  20 . The bead  50  spans here over the entire circumferential surface  69  of the free shank  22  and creates simultaneously a heel  46  with regard to the axial direction  70  as an option. The commutator hook  20  is hereby construed narrower in circumferential direction  68  than the opposing counter surface  26 . 
     The electrodes  40  are for example designed as wolfram—electrodes, whereby one electrode  40  is put on the end of the free shank  22  and the other electrode  40  covers the bending area  24  of the commutator hook  20 . During the energization of the electrodes  40  they are tracked towards the counter surface  26  so that the free shank  22  lies on at the wire windings  28  as well as on the counter surface  26  due to the heat forming. 
     It shall noted that with regard to the embodiments that have been shown in the figures and the description various combination possibilities of the individual characteristics are possible. Thus the arrangement of the solder  34  or example can be varied according to the application and if necessary be inserted point by point in the contact area between the wire winding  28  and the commutator hook  20 . Also different materials can be used as a solder  34 , whose melting temperature prevents a melting of the commutator hook  20  and/or the wire windings  28 . Moreover a concrete form and connection of the commutator hook  20  at the commutator  12  can be varied, whereby in particular the axial construction length of the commutator can be reduced by the producing procedure according to the invention. Preferably the electrodes  40  are used with a square-shaped contact face. The forming of the electrodes  40  as well as their pressing device can also be adjusted to the electric machines that have to be produced. Preferably the procedure according to the invention is applicable for the production of a rotor of an electromotor for movable parts in the motor vehicle.