Abstract:
A method for fixing an electrical element, in particular a diode ( 20 ), using an insert, in particular a diode socket ( 26 ) in a support body ( 23 ), is disclosed. The insert, in particular, the diode socket ( 26 ), is applied in an opening ( 35 ) in the support body ( 23 ). Said method is characterized in that, in a further step, material of the support body ( 23 ) around the insert is forced into the insert, in order to achieve a strong connection between the electrical element and the support body ( 23 ).

Description:
BACKGROUND INFORMATION  
         [0001]    The invention relates to a method for fixing an electrical element, in particular a diode, and a module according to the general class of the independent claim. It is made known in European patent publication 0 329 722 B1 that electrical elements, configured as diodes, for rectifier devices for three-phase generators are inserted, via pressing, into receptacle holes in support bodies. To accomplish this, a bore is created in a support body, which interacts with a diode socket to produce an interference fit. The diode socket and the diode are then pressed into said bore. The disadvantage of this configuration is that the bore must be relatively small in order to ensure that the diode is held securely in the bore and to ensure sufficient heat transfer from the diode to the support body. Associated with this is the fact that the high press-in forces can result in deformation of the diode socket and, therefore, to preliminary damage of the installed diode chip. Diodes that have been pressed in in this manner can fail relatively early. Moreover, mechanical tolerances at the diode socket and in the bore result in transitions between diodes and support bodies that are not entirely thermally optimal. This can result in high temperatures forming at the diodes and, as a result, operating failure.  
         ADVANTAGES OF THE INVENTION  
         [0002]    The method according to the invention for fixing an electrical element, in particular a diode, having the features of the main claim, has the advantage that the pressing between insert and bore in the support body can be further reduced, yet a good hold of the electrical element in the support body and an equally good thermal transition between electrical element and support body can be achieved.  
           [0003]    The failure rates of electrical elements is reduced, because the press-in forces are reduced.  
           [0004]    Advantageous further developments of the method for fixing an electrical element according to the main claim are possible due to the measures listed in the subclaims.  
           [0005]    If material of the support body is forced into the insert by a radial force using a punch, the method is simple and economical.  
           [0006]    If the punch has a generally conical shape, the effect of the displacement of the material into the insert is enhanced particularly well, and punching forces can be reduced. As a result, the amount of energy used in the production method is reduced, and the reliability of the displacement process is improved. If only the punch has a generally conical shape, material can be displaced in the area of the end surface, i.e., on the end surface of the insert that is furthest away from the connection wire. This is an area that, in the case of a diode, for example, is relatively far away from the diode chip, so that the danger of destroying said diode chip is particularly minimal here.  
           [0007]    If the axial force of the punch is absorbed by a counter punch, the position of the support body before and after the assembly procedure in the direction of the connection wire does not have to be changed, since the two punches press on the support body at the same time. A support body that is annular in shape, for example, need only be turned around its ring axis.  
           [0008]    A uniform displacement around the insert is achieved by the fact that the punch and counter punch are both configured annular in shape.  
           [0009]    A displacement of the material of the support body that is particularly uniform and central, i.e., symmetrical in terms of the plate strength of the support body, is achieved by the fact that the punch and the counter punch have a generally conical shape.  
           [0010]    A module for electrical machines that is produced according to the individual method steps has particularly reliable support bodies with electrical elements, since the electrical elements undergo a particularly minimal amount of preliminary damage. 
       
    
    
     DRAWING  
       [0011]    Exemplary embodiments of methods, according to the invention, for fixing electrical elements, in particular power diodes, in support bodies, and a module for electrical machines with electrical elements pressed in according to the method are shown in the drawing.  
         [0012]    [0012]FIG. 1 shows a power diode before it is pressed into a support body,  
         [0013]    [0013]FIG. 2 shows the power diode pressed into the support body,  
         [0014]    [0014]FIG. 3 shows the power diode before material is forced into the diode socket,  
         [0015]    [0015]FIG. 4 shows how material is forced into the diode socket by the punch,  
         [0016]    [0016]FIG. 5 shows a variant of the method, whereby the punch and the counter punch are both generally conical in shape,  
         [0017]    [0017]FIG. 6 shows a rectifier module for electrical machines with a support body in which at least one diode is fixed according to the method according to the invention.  
     
    
     DESCRIPTION  
       [0018]    A diode, which is configured as a power diode  20 , and a support body  23  are shown in FIG. 1. Power diode  20  consists of three different sections. The first section is the insert that is configured as diode socket  26 —sometimes also referred to as a heat sink. The second section is the actual rectifier part  29 . Diode head lead  32 , as the connection wire, extends out of said rectifier module and forms the third section. Support body  23  has an opening  35  that is typically configured as a cylindrical bore. Diode socket  26  is usually configured as a cylindrical part and includes ribbing that is shown on its outer circumference. The diameter of opening  35  is usually slightly smaller than the diameter of diode socket  26 , so that a considerable amount of force is required to press power diode  20 , with its diode socket  26 , into opening  35 . In the case of the present invention, in the first exemplary embodiment, opening  35  is still configured with a diameter that is smaller than that of diode socket  26 . However, the fit dimension between opening  35  and diode socket  26  is modified in such a manner that the amount of force required to install diode socket  26  in opening  35  is reduced compared to the related art.  
         [0019]    In the first step, power diode  20 , with its diode socket  26 , is pressed into opening  35 , resulting in the condition shown in FIG. 2.  
         [0020]    With reference to FIGS. 3 and 4, it will now be explained hereinbelow how material of the support body  23  around diode socket  26  is forced into diode socket  26  in a further step. To this end, a punch  40  and a counter punch  43  are required in a first exemplary embodiment. Support body  23  with power diode  20  is brought to rest against counter punch  43  via a surface  46  of support body  23 . Counter punch  43  has a generally hollow-cylindrical shape, whereby rectifier part  29  and diode head lead  32  extend inside a hollow-cylindrical part  49 . Support body  23  has a counter surface  52  that is opposite to surface  46 . If support body  23  rests against counter punch  43 , material of support body  23  is forced into diode socket  26  using punch  40 , which is also configured hollow-cylindrical in shape. To this end, punch  40  is moved toward counter surface  52 , a generally conical, e.g., hollow-conical shape  55  of punch  40  ultimately penetrates the material of support body  23 , FIG. 4, and displaces material of support body  23  in the direction of an axis  58  of power diode  20  using the pitch of the conical shape of punch  40 . A radial force is produced by conical shape  55  of punch  40 , which ultimately brings about the displacement of material into diode socket  26 . A general axial force of punch  40 , which is ultimately required to displace material, is absorbed by counter punch  43 .  
         [0021]    In deviation from the exemplary embodiment according to FIG. 3 and FIG. 4, a second exemplary embodiment according to FIG. 5 will be discussed briefly.  
         [0022]    In this case, a punch  40  and a counter punch  43  bring about the displacement of material of support body  23  into diode socket  26  in similar fashion. In contrast to the previous exemplary embodiment, counter punch  43  is configured exactly like punch  40 , i.e., counter punch  43  also has a generally conical or hollow-cylindrical shape  55 , which is suited to applying a radial force with which material of support body  23  is forced into diode socket  26  from counter punch  43  outward. In a fashion that is similar to the exemplary embodiment according to FIG. 3 and FIG. 4, support plate  23  is first brought to rest against counter punch  43  in this case as well, and punch  40  is moved toward counter surface  52 . Punch  40 , with its conical shape  55 , penetrates the material of support body  23 . According to the general principle that, for every action there is an equal and opposite reaction, and due to the conical shape  55  of counter punch  43 , counter punch  43  also penetrates the material of support body  23  with its conical shape  55 , thereby also bringing about a displacement of the material of support body  23  from surface  46  into diode socket  26 . Finally, as with the exemplary embodiment according to FIG. 3 and FIG. 4, both punch  40  and counter punch  43  are lifted away from support body  23  and, ultimately, support body  23  with fully-installed power diode  20  is removed from the fabrication device.  
         [0023]    In principle, it is not necessary for punch  40  or counter punch  43  to both have a conical or hollow-conical shape  55 . In principle, it is possible to displace the material of support body  23  into diode socket  26  using a punch  40  that is configured exactly like counter punch  43  in FIG. 3, so that two basically blunt punches  40 ,  43  enable a displacement of material from surface  46  as well as counter surface  52 .  
         [0024]    [0024]FIG. 6 shows a rectifier module  65  in a schematic representation of a module of the type required for three-phase generators for motor vehicles. Rectifier module  65  includes at least one support body  23  on which a power diode  20  is mounted, whereby the at least one power diode  20  is fixed according to one of the methods described hereinabove. Power diodes  20  are surrounded by obvious pinches at a plurality of locations.  
         [0025]    As an alternative, the dimension of opening  35  and the diameter of diode socket  26  can also be configured as a clearance fit. The pressing between diode  20  and support body  23  is not produced until the support body material is displaced. The displacement can also be carried out in accordance with one of the exemplary embodiments described previously.