Abstract:
The invention relates to an arrangement for holding a plurality of electric capacitor assemblies, particularly assemblies having live housings. The arrangement has a carrier having a through-passage for introducing one of the assemblies and further has at least one bearing ring for mounting an assembly. The bearing ring is matched to the dimensions of the through-passage and the assembly such that the assembly when extending through the through-passage, is in contact with the inner edge of the through-passage via the bearing ring, but not in direct contact with the inner edge of the through-passage.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an arrangement for holding a plurality of electric capacitor assemblies, particularly assemblies having live housings. The invention further relates to a method for holding a plurality of capacitor assemblies. One special aspect of the invention relates to the storage of electrical energy in a battery (that is, an arrangement with a plurality) of capacitor assemblies. 
     2. Description of Related Art 
     Capacitors have been used for some years to store electrical energy, particularly the braking energy of railway vehicles. The energy stored in the capacitors can be used, in particular, for the subsequent start-up or acceleration process. 
     Capacitor assemblies are usually manufactured and offered for sale in housings. In one customary structural shape, the housing is cylindrical and is connected to one of the two electrical potentials of the capacitor or of the plurality of capacitors arranged in the housing. The other potential is connected, for example, to a pin-shaped contact on the front of the housing. The invention also relates to other structural shapes, however. 
     In particular due to the live housing, the assemblies are usually mounted using plates made of electrically insulating material to be able to arrange a plurality of assemblies next to one another and to make the electrical connection in the manner desired. In particular, the assemblies may be connected electrically in series and/or in parallel. 
     The expenditure for manufacturing the insulating plates and for mounting the assemblies to the insulating plates is relatively high. A carrier to mount a plurality of capacitor assemblies would be beneficial where the carrier can be manufactured from any material, in particular, optionally of plastic or metal. Metal provides great stability and durability. 
     Consequently, it is the object of this invention to specify an arrangement and a method of the type cited at the beginning for holding a plurality of capacitor assemblies regardless of whether the capacitor assemblies are live around the circumference of their housing or not. 
     SUMMARY OF THE INVENTION 
     Using a carrier that provides a through-passage for each of the capacitor assemblies to be held on the carrier is proposed. The individual assemblies are arranged on the carrier such that they extend through the through-passage. In this respect, the assemblies are each combined with a bearing ring used to make contact with the inside edge of the through-passage. The bearing ring is a ring-shaped member used to mount the assembly in the through-passage. In this way, the outer circumference of the assembly does not make direct contact with the inside edge of the through-passage but rather only indirectly by way of the bearing ring. The bearing ring can, for example, be made of an electrically insulating material, for example, polypropylene or polyamide. Other electrically insulating materials may also be used. If the outer circumference of the assembly is not live, however, a bearing ring made of metal or another electrically conducting material may also be used. In all of these cases, the material of the carrier, for example, a plate-shaped carrier with a plurality of through-passages arranged next to one another, can be any material, for example, metal. The bearing ring, for example, running around the inside edge of the through-passage around the outside circumference of the assembly, allows simple installation of the assembly in the through-passage and also prevents, as mentioned, direct mechanical contact between the assembly in the carrier. 
     In particular, the following is proposed: An arrangement for holding a plurality of electric capacitor assemblies, particularly assemblies having live housings wherein the arrangement has the following: 
     a carrier with a through-passage to insert each of the assemblies, 
     at least one bearing ring for mounting one assembly wherein the bearing ring is matched to the dimensions of the through-passage and of the assembly so that the assembly, when extended through the through-passage, makes contact with the inside edge of the through-passage by way of the bearing ring but is not directly in contact with the inside edge of the through-passage. 
     In addition, a method for holding a plurality of electric capacitor assemblies is proposed, particularly assemblies having live housings wherein to install the assemblies: 
     one assembly in each case is inserted into one of the through-passages of a carrier having a plurality of through-passages such that the assembly extends through the through-passage, 
     before, during and/or after insertion of the assembly in the through-passage, a bearing ring is inserted in the through-passage so that it is arranged between the outside circumference of the assembly and the inside edge of the through-passage and holds the assembly to the carrier as soon as installation has been completed so that the assembly makes contact with the inside edge of the through-passage by way of the bearing ring but is not directly in contact with the inside edge of the through-passage. 
     Developments of the method result from the following description of developments of the arrangement and from the included patent claims. 
     In one preferred development, the arrangement has a clamp ring that extends, when the assembly is installed, between the outside circumference of the assembly and the material of the carrier in such a way that the assembly, the clamp ring and the bearing ring are held to the inside edge of the through-passage by clamping action. 
     Holding the assembly by means of clamping action simplifies installation and still provides a reliable holding connection between the assembly and the carrier. In particular, one clamp ring is provided for every through-passage in which an assembly is held. 
     In a particular development, an axial direction is defined by the through-passage and extends from one side of the carrier through the through-passage to the opposite side of the carrier wherein the arrangement is designed such that the clamp ring is to be moved in the axial direction to generate the clamping action to install the assembly. Preferably, the clamp ring has a first thread and the bearing ring has a second thread that work together in such a way that, using a screwing motion of the bearing ring and/or of the clamp ring, the clamp ring is moved in the axial direction and, in this way, is brought into an axial position in which the clamp ring generates the clamping action. However, other embodiments are also possible in which the axial motion of the clamp ring is effected in some other manner. For example, the bearing ring may not have a thread and the mating thread is formed on the inside edge of the through-passage or on the outside circumference of the assembly. 
     In addition, the thread need not absolutely be formed on the clamp ring. Rather, for example, an axial movement that results in the generation of the clamping effect by the clamp ring using an appropriate screwing motion can be effected by the formation of mating threads on at least two of the following parts: carrier, bearing ring, assembly, some additional part. 
     The clamp ring, for example, has members running parallel to the axial direction that taper in size in the radial direction along their length. These members can interact with corresponding sections of the bearing ring to develop the clamping action with a relative axial motion of the bearing ring and the clamp ring. The tapering members of the clamp ring, however, need not absolutely interact with sections of the bearing ring specially designed for the clamping action. Rather, these sections of the clamp ring may also interact with the housing, some additional component of the arrangement and/or the inside edge of the through-passage. Furthermore, the sections of a single member tapering in the axial direction can be formed, for example, by a ring-shaped portion of the bearing ring. 
     For example, the through-passage may be a circular opening, that is, the opening may have a circular cross-section. Particularly in this case, the capacitor held in the through-passage may unintentionally rotate. For this reason, the following is preferably proposed: At least one recess extending in the radial direction is arranged on the inside edge of the through-passage wherein the bearing ring has a projection extending outward in the radial direction and wherein the projection engages in the recess in such a way that the bearing ring is secured against a rotational movement in the circumferential direction of the edge of the through-passage. 
     The bearing ring preferably extends in the axial direction over a length greater than the length of the through-passage. In this manner, holding the assembly in the through-passage can be further stabilized. 
     Furthermore, it is possible that the dimensions of the bearing ring in the axial direction are designed so that a subsection of the bearing ring can be inserted into the through-passage or the ring can even be moved through the through-passage but another subsection of the bearing ring has a larger cross-section than the through-passage or is at least wider than the through-passage so that the other subsection cannot be inserted into the through-passage. In this way, the holding connection of the assembly is additionally stabilized on the carrier. When using a clamp ring, in addition, the subsection of the bearing ring that was moved through the through-passage can be pressed radially outward as the clamping action develops so that this subsection is secured against being moved back again unintentionally in an axial direction through the through-passage. 
     Preferably, the assembly or the plurality of assemblies is held in one through-passage of the carrier via a bearing ring not just on one end but rather on a second section located at some distance in the axial direction. Consequently, the assembly is mounted in a particularly secure and permanent manner. Particularly, it is proposed that the arrangement have a second carrier with at least a second through-passage to insert an assembly wherein the assembly, when installed, extends through one of the through-passages in the first carrier and, in another section located at some distance in the axial direction from the first carrier, through the second through-passage and is held in the second through-passage by means of a second bearing ring. 
     The invention further relates not only to the arrangement for holding a plurality of capacitor assemblies but also to such an arrangement where the capacitor assemblies are in fact present. In particular, this can include an energy storage device for storing electrical energy in the various capacitor assemblies. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the invention are now described with reference to the accompanying drawing. The individual figures of the drawing are as follows: 
         FIG. 1  shows an initial exemplary embodiment for an arrangement with one carrier, one bearing ring and one capacitor assembly, 
         FIG. 2  depicts the bearing ring as per  FIG. 1 , 
         FIG. 3  illustrates a mounting ring of the arrangement as per  FIG. 1 , 
         FIG. 4  is a sectional view through a part of the arrangement as per  FIG. 1 , 
         FIG. 5  shows a second arrangement with carriers and a capacitor assembly arranged in the through-passages of the carriers, 
         FIG. 6  depicts an axial sectional view through a subsection of the arrangement shown in  FIG. 5  wherein the figure represents a state prior to generating a clamping action by way of the axial motion of a clamp ring, 
         FIG. 7  shows a sectional view as in  FIG. 6  wherein the figure, however, represents the finished installation state of the capacitor assembly in the through-passage, 
         FIG. 8  shows a bearing ring of the arrangement depicted in  FIG. 5 , 
         FIG. 9  shows a clamp ring of the arrangement depicted in  FIG. 5 , 
         FIG. 10  depicts a subsection of the arrangement illustrated in  FIG. 5  with a ring-shaped tool for producing a screwing motion, 
         FIG. 11  is a third exemplary embodiment of an arrangement with one bearing ring and one carrier, 
         FIG. 12  shows the bearing ring of the arrangement in  FIG. 11 , 
         FIG. 13  illustrates a perspective view of the mounting of a capacitor assembly to two carriers, each having a bearing ring, 
         FIG. 14  shows an arrangement with a plurality of capacitor assemblies that are electrically connected to one another, 
         FIG. 15  is a subsection of the arrangement as per  FIG. 14  wherein, however, the electrical connecting member for connecting two capacitor assemblies is not yet in contact with the capacitor assemblies, and 
         FIG. 16  illustrates an axial longitudinal view through a capacitor assembly and a bearing ring of the third exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows an initial embodiment of an arrangement with a capacitor assembly  3 , a bearing ring  5  and a carrier  1 . The carrier  1 , which is not shown completely in  FIG. 1 , has a plurality of circular through-passages  4  that are arranged in rows and columns next to one another. A bearing ring  5 , preferably made of electrically insulating material, is arranged in one of these through-passages  4 , namely the bottom left through-passage  4  shown in  FIG. 1 , so that the bearing ring  5  extends through the through-passage  4  (in the axial direction) wherein one subsection  6   a  of the bearing ring  5  is located in the illustration in front of the through-passage  4  and an additional subsection  6   b  is located in the illustration behind the through-passage  4 . 
     Using this bearing ring  5 , one preferred arrangement of bearing rings is described that could also be implemented differently. The bearing ring has on its outside circumference in at least one subsection  6   a  a plurality of slots  7  located around the circumference. This facilitates the manual installation of the holding connection. 
     As an alternative or in addition to this, a subsection  6   a  of the bearing ring  5  is designed so that the subsection  6   a  cannot be inserted through the through-passage  4  because the diameter of the subsection  6   a  is greater than the inner diameter of the through-passage  4 . It can be seen in  FIG. 4  that the material  9  at the end of the subsection  6   a  defines a contact surface  10  running around the through-passage  4  and making contact with the material of carrier  1  without being present inside the through-passage  4 . 
     The design of the bearing ring  5  can also be seen in  FIG. 2  that depicts the bearing ring  5  alone. 
     The arrangement as per  FIG. 1  includes a mounting ring  15 , which cannot be seen in  FIG. 1 , that is made of metal for example and that has a plurality of projections  16  tapering to a point at their free end distributed on the radially inner side of the ring around the inner circumference. In this respect, the projections  16  do not extend only radially inward but also in an axial direction. This weir  15  is pressed into a slot  19  (see  FIG. 4 ) in a section  20  of the bearing ring  5  projecting radially inward by inserting additional projections  17  distributed around the circumference of the weir  15  and extending in the axial direction opposite to the direction that the projections  16  extend. Next, the bearing ring  5  prepared in this way with the weir  15  on the one hand and the assembly  3  to be held on the other hand are moved in an axial direction relative to one another (wherein the assembly  3  is inserted inside the bearing ring  5 ) such that the projections  16  dig into the surface of the assembly  3  and the desired axial relative position on the external circumference of the assembly  3  as shown in  FIG. 4 . 
     Either the bearing ring  5  with the weir  15  it contains is inserted in the through-passage  4  of the carrier  1  before inserting the assembly  3  in the bearing ring  5  or after inserting the assembly  3 . The completely installed arrangement can be seen in the illustration of  FIG. 4 . 
     Optionally, the subsection  6   b  that is moved through the through-passage  4  to reach the completely installed position can also have sections projecting outward that, however, still allow the section  6   b  to move through. For example, these sections may allow slight elastic deformation and/or be moved through the through-passage  4  by scraping under radial pressure so that unintended movement of the bearing ring  5  in the opposite direction is hindered or impossible. 
     A second embodiment is shown in the  FIGS. 5 to 10 . The arrangement has one carrier  31 . A bearing ring  45  extends through the carrier  31 . The held capacitor assembly  3  extends inside the bearing ring  45  through a through-passage  4  in the carrier  31 . In the same manner, the assembly  3  can be mounted at its back end in a second carrier. 
     A clamp ring  36  is provided in the through-passage  4  for the secure and permanent mounting of the assembly  3  but this ring (as shown in  FIGS. 6 and 7 ) does not extend into the through-passage  4 . Despite this, when installed, it generates a clamping action, that is, forces that act particularly in the radial direction and that hold the assembly  3  to the carrier  31  by means of the clamping action. In this process, the clamping force is transferred from the radial outside to the radial inside first from the carrier to the bearing ring  45 , then from this ring to the clamp ring  36  and then from this ring to the outer surface on the circumference of the assembly  3 . A clamping force is not transferred directly from the bearing ring  45  to the assembly  3 . 
       FIG. 8  depicts an exemplary embodiment of a bearing ring  45  that, with regard to the shape of the outer circumference, may be designed like the bearing ring  5  as per  FIG. 2 . Particularly, the bearing ring may have a first section  46   a  and a second section  46   b  wherein only the second section  46   b , but not the first section  46   a , can be inserted through the through-passage  4  of the carrier  31 . Even more characteristics described using  FIG. 2  or the description of the bearing ring  5  may be present either individually or in any combination with the bearing ring as per  FIG. 8 , too. As shown in  FIG. 8 , the exterior design, that is, the design on the outside circumference of the bearing ring  45  may deviate from the design of the bearing ring  5 . In particular, this bearing ring has engaging members  48  on the transition section between the first section  46   a  and the second section  46   b  that project in an axial direction from the first section  46   a . Two of these are visible in  FIG. 8 . For example, two additional engaging members are located at the same angular intervals around the longitudinal axis on the outer circumference of the bearing ring  45 . The quantity of such projections, however, is not limited to four. Rather, one single such projection is sufficient in principle. However, a plurality of such projections may also be provided at different angular intervals. In each case, the inside edge of the through-passages or at least one through-passage of the carrier  31  (as indicated, for example, by the reference number  39  on carrier  31  in  FIG. 5 ) has at least one corresponding notch so that all projections on the bearing ring can fit into one of the notches  39  and, in this way, prevent unintended rotation of the bearing ring about the longitudinal axis running in the axial direction. 
     Similar to the bearing ring  5  as per  FIG. 2 , sections  49  projecting radially outward may be formed on the outer circumference of the second section  46   b , these sections, for example directed in the axial direction to the first section  46   a , rising from the level of the outer circumference  46   b  and having an edge extending in the radial direction on their end adjacent to the first section  46   a . In this respect, the distance of the edge from the first section  46   a  is preferably as large as the thickness of the through-passage in the carrier  31  in the axial direction. In this way, the bearing ring  45 , with the free end of the second section  46   b  in front, can be inserted through the through-passage  4  until the face area of the first section  46   a  makes contact with the material of the carrier  31 . In this case, the projection  49  with its edge prevents the bearing ring  45  from being unintentionally removed from the through-passage again or from moving in an axial direction within the through-passage. 
     Another characteristic also explained using the exemplary embodiment as per  FIG. 8  just like the other characteristics described before but also present in other embodiments individually or in combination with other characteristics is an internal thread in the portion of the first section  46   a  extending from the free end of the bearing ring  45  in the direction of the second section  46   b . The internal thread is identified in  FIG. 8  by the reference number  50 . Corresponding to the internal thread, the clamp ring  36  shown in  FIG. 9  has an external thread on its outer circumference. However, in the exemplary embodiment shown in  FIG. 9 , the external thread  51  does not extend to the free end of the clamp ring  36  in the axial direction. Rather, the clamp ring  36  has a plurality of ring-shaped segments  54  on this free end that are each separated from the adjacent segments  54  by a notch  55 . As shown in  FIG. 10 , one projection  59  of an assembly tool  58  can be inserted into each of these notches  55 . The assembly tool  58  is designed to be circular and has a through-passage  61  in its center area wherein the through-passage  61  is formed by a hexagonal-shaped material to allow, for example, the placement of a wrench. If the assembly tool is used, a contact pin  30  projecting in an axial direction (also see  FIG. 1 ,  FIG. 5  and  FIG. 10 ) extends at least into the through-passage  61 . This contact pin  30  of the capacitor assembly  3  serves as the electrical connection for the assembly  3 . 
     Using the assembly tool  58 , the clamp ring  36  can be screwed into the bearing ring  45  in an axial direction whereby members  69 , located on the front end in the axial direction facing the rear end in the axial direction with the segments  54 , said members being tongue-shaped, i.e., running to a point (as shown in  FIGS. 6 and 7 ), are forced between the material of the bearing ring  45  and the assembly  3 , generating the desired clamping action in this manner. 
     In general, not just in the embodiment of the clamp ring shown in  FIGS. 6 ,  7  and  9 , a clamp ring may have at its front end in the axial direction at least one section that tapers in the direction of the free end, in particular, tapers such that the thickness of the free end measured in the radial direction decreases. Such a tongue-like design allows generation of the desired clamping action in a simple way. 
     Optionally and, for example, as shown in the exemplary embodiment as per  FIGS. 6 and 7 , the bearing ring can have on its inner circumference a surface section running in an axial longitudinal sectional view obliquely from radially outside to radially inside and, the same time, in the axial direction, the tongue-like free end of the clamp ring moving along this section during its axial motion. Such a beveled surface section is identified in  FIGS. 6 and 7 , for example, using the identification number  64 . In the completely installed position shown in  FIG. 7 , the free end of the clamp ring  52  even extends beyond the beveled section of the bearing ring  45 . 
     In the exemplary embodiment shown in  FIG. 9 , the tongue-like members  69  are distributed uniformly around the circumference and are in each case separated from one another by a notch  70  around the circumference. In particular, if the plastic material used, for example, undergoes plastic deformation due to the clamping pressure, the notches  70  may be eliminated. 
     Another embodiment of a bearing ring and a corresponding arrangement are now described using  FIGS. 11 and 12 . The bearing ring  85  has two areas  86   a ,  86   b  located one behind the other in the axial direction. The area  86   b  of the bearing ring is inserted in the axial direction through the corresponding through-passage  4  of a carrier  81  until an abutment surface  91  of the first area  86   a  contacts the material of the carrier  81 . 
     As can easily be seen particularly in  FIG. 12 , the bearing ring  85  has on its inner circumference a plurality of sections  98  projecting linearly in the axial direction. The ends lying inside in the radial direction of these sections  98  are positioned such that a capacitor assembly  3  held by the bearing ring  85  is held by the clamping action of the sections  98  (also see  FIG. 16 ). 
     In addition, the section  86   b  immediately in front of the abutment surface  91  around its outer circumference has a plurality of sections  99  projecting radially outward that the bearing ring  85  uses for support by creating a clamping action on the inner edge of a through-passage  4  of the carrier  81  when the bearing ring is installed in the through-passage  4 . Both the material of the sections  99  and of the sections  98  may undergo elastic deformation during the creation of the clamping action. 
     On its free end, the section  86   b  has sections  92   a ,  92   b  running radially inward. In the exemplary embodiment, two such sections  92  are formed facing each other on opposite sides in the radial direction. The sections  92  prevent a capacitor mounted in the bearing ring  85  from escaping from the free end of the second section  86   b.    
     In a particular embodiment of the sections  92 , at least one section  92  has a projection  94  on its radially inward edge and this section can move in the axial direction if an appropriate pressing force is applied by the mounted capacitor assembly on the projection  94 . In this respect, the free end of the projection  94  is not under stress if no axial force is being exerted on it in an axial position in front of (in the illustration of  FIG. 12 , below) the section  92 . For this reason, the capacitor assembly, if it cannot exert the force required to deform the projection  94  or if it can only exert part of this force, can touch only the projection  94  but not the section  92 . Depending on the axial force, the capacitor assemblies may be mounted in a different axial position in the bearing ring  85 . For example,  FIG. 15  shows a capacitor assembly  3   a  on the left that also makes contact with the section  92  while a capacitor assembly  3   b  is shown on the right in  FIG. 15  that only makes contact with the projections  94  but not the section  92 . In this way, it is possible to implement reliable reverse voltage protection (that is, protection against connecting the incorrect electrical connections of different capacitor assemblies). For example, the connector  30   a  of the capacitor assembly  3   a  is equipped with a projecting contact pin as well as a ring-shaped section  96  having a larger outer diameter than the contact pin  95 . This ring  96  indicates that this involves the terminal post of the first type (for example, the positive post). 
     On the other hand, the terminal post  97  of the capacitor shown on the right in  FIG. 15  does not have such an additional ring. An electrical terminal post of the other type (for example, the negative post) is identified in this way. 
     For example, the capacitors  3   a ,  3   b  are to be connected in series. To do this, the connecting member  100  illustrated above in  FIG. 15  is used and this member has one through-passage for each of the contact pins  95 ,  97 . For example,  FIG. 14  shows the installed state. As the front, free end of the ring-shaped section  96  is located at a different axial position (higher, in  FIG. 15 ) than the front surface of the capacitor  3   b , the connecting member  100  has two bends in its central area along its length so that while both ends  101   a ,  101   b  run parallel to one another but are not in the same plane. 
     The bends are identified by the reference numbers  102   a ,  102   b . This design of the connecting member  100  also contributes to reverse voltage protection. If the two capacitor assemblies to be connected in series were positioned with the same post next to one another (for example, the positive post) differently than shown in  FIG. 15 , this situation would be obvious because both posts would have either one ring-shaped section  96  or none at all. When fastening the connecting member  100  with the bent center section to the contact pins (for example, by screwing nuts onto the outer thread of the contact pins), the surface of the connecting member  100  would not make contact with as complete a surface as possible either on the front end of the ring-shaped sections or the front end of the assembly housing and would thus be easy to recognize. Expressed in other terms, the design with two bends for the connecting members to the axial ends of the assemblies with the opposite circumstances would lead to the situation that the assemblies are brought into an appropriate axial position because of the fastening of the connecting members to the contact posts. If the assemblies are of incorrect polarity, that is, mounted in an inverted position, the surface of at least one of the contact members would not make as complete a surface contact as possible on one of the assemblies. 
     It can be seen in  FIG. 15  that the sections  92  of the bearing rings  85  extending inward in the radial direction leave some free space open between them over which the connecting member  100  can extend when installed. 
     It can be seen in  FIG. 13  how a capacitor assembly  3  with the help of two bearing rings, for example, of the type of bearing rings that were described using  FIG. 11  and  FIG. 12 , and with the help of two carriers  81   a ,  81   b  can be held securely. The carriers  81  have additional through-passages  106  between the through-passages  4  for installing the capacitor assemblies. For example, using stud bolts  107  and nuts  108 , the carriers  81   a ,  81   b  are screwed to one another so that the assemblies cannot escape unintentionally from the bearing rings  85 . 
       FIG. 14  shows the installed state with a total of four installed capacitor assemblies  3  of which the assemblies above one another are connected electrically to one another on the axial side at the front by means of a connecting member  100  with two bends. In this figure, the connecting members  100  have not yet been screwed tight or fastened in another manner to the front contact surfaces of the assemblies  3 . 
       FIG. 16  shows an axial longitudinal view through an axial end section of a capacitor assembly  3  and a bearing ring  85  arranged in this end section. On the left in the figure can be seen the section  92  extending inward in the radial direction with the projection  94  being slightly offset in the axial direction. In general, it is valid that the projections  94  make it possible for the capacitor assembly to be shifted slightly in the axial direction, in particular if one or more such projections are located on both opposite axial ends of the assembly. For example, the shift in the axial direction, as mentioned, is effected by the connecting members  100  when these are fastened to the contact pins.