Patent Publication Number: US-11024988-B2

Title: Conductor terminal with sheet metal part having arched root area from which clamping spring extends

Description:
This nonprovisional application is a continuation of International Application No. PCT/EP2017/071541, which was filed on Aug. 28, 2017, and which claims priority to German Patent Application No. 10 2016 116 510.7, which was filed in Germany on Sep. 2, 2016, and which are both herein incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a conductor terminal for clamping an electric conductor, which comprises an insulating material housing and a contact element, the contact element having a sheet metal part with at least one clamping spring arranged thereon. The insulating material housing has at least one insertion guide channel leading to a particular clamping spring. An opening is present in the sheet meal part for receiving an electric conductor inserted into an associated insertion guide channel. The invention also relates to a conductor terminal comprising a sheet metal part and at least one clamping spring protruding from the sheet metal part, which is connected to the sheet metal part in a root area of the sheet metal part. 
     Description of the Background Art 
     Conductor terminals are known, for example, in the form of a socket terminal, in which multiple electric conductors are electrically conductively connected to each other with the aid of a shared contact element. 
     EP 1 855 353 B1, which is incorporated herein by reference, describes a conductor terminal comprising a spring steel sheet and a busbar mounted in this spring steel sheet. The clamping points for clamping an electric conductor are each formed between the free ends of leaf spring tongues and the busbar. The leaf spring tongues are cut away from the spring steel sheet in such a way that their tongue roots are fixedly connected to the upper edge area of the spring steel sheet. The busbar is inserted into a V-shaped receiving space. The length of the leaf spring tongues are dimensioned in such a way that their tongue ends pass through the window recess of the spring steel sheet when the clamping point is closed and unoccupied and abut the underside of the busbar. 
     DE 40 03 701 A1, which corresponds to U.S. Pat. No. 5,098,316, which is incorporated herein by reference, shows an equipment terminal comprising a contact application sheet, which is bent in the shape of a V in the direction of the clamping limb section, forming a hollow. This forms a molded surface of the contact application sheet, which represents one lateral half of a socket part of a plug connection integrated into the equipment terminal. 
     DE 196 54 523 A1, which corresponds to U.S. Pat. No. 6,132,238, discloses a conductor terminal, which is formed from a busbar rod and a spring steel sheet, from which leaf springs are stamped in the manner of tongues, whose stamped-out tongue ends are oriented opposite the busbar rod. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide an improved conductor terminal, which improves, in particular, the clamping of multi-wire conductors. 
     In an exemplary embodiment, it is proposed that the insulating material housing can have channel side walls which delimit the insertion guide channel and extend into the opening. Due to the fact that the channel side walls now protrude into the opening of the sheet metal part, an improved guidance, in particular of multiwire conductors through the opening is facilitated. The strands are held together beyond the clamping point with the aid of these channel side walls. When clamping an electric conductor, a displacement of the strands is prevented, for example due to an application of force by the clamping spring, or at least the risk of displacement is reduced, in that the channel side walls provide a lateral guidance of the electric conductor to be clamped beyond the clamping point in the conductor insertion direction. 
     The sheet metal part may be bent in the area of the opening. The channel side walls then pass through the opening in the bent section of the sheet metal part. This facilitates a highly compact specific embodiment of the conductor terminal and a good guidance of the conductor. 
     Two channel side walls, which are spaced a distance apart, disposed at a distance from each other and inserted into the opening, may be present for each insertion guide channel. This makes it possible to guide the conductor on both sides. 
     The channel side walls may be T-shaped in cross section, in particular for the outer channel side walls, or they may be H-shaped in cross section, i.e. having a double T shape. These H-shaped channel side walls in cross section may be provided, in particular for the insertion guide channels situated side by side. These T- and H-shaped cross sections increase the stability of the channel side walls in a compact design. 
     Alternatively or in combination with this approach, it is proposed that the sheet metal part is arched in the root area. The arch has a groove base of a groove of the arch oriented transversely to the main extension direction of the clamping spring. This arch is present not only in the area of the tongue root of the clamping spring tongue but is also situated in the adjacent part of the sheet metal part, which transitions into side webs delimiting the opening. The spring elasticity of the clamping spring after stamping is improved with the aid of this arch. The clamping spring is namely first bent back against the spring force of the clamping spring in the arch and then elastically deformed. The length of the clamping spring may be shortened thereby, or a conductor terminal having a very low height may be implemented. When inserting a multiwire conductor in particular, the arch furthermore results in the fact that the conductor strikes the elastic part of the clamping spring, so that the clamping spring is already elastically deformed when the electric conductor is inserted. This reduces the risk of strands of a multiwire conductor becoming displaced, compared to a conductor terminal without an arch of this type. This is also achieved in that, due to the arch, the spring elasticity of the sheet metal part is increased in the root area of the sheet metal part, and the latter is spring-elastically deformable, together with the side webs, when an electrical conductor is clamped. 
     The middle extension of the clamping spring from the root area of the clamping spring to the clamping end of the clamping spring is viewed as the main extension direction of the clamping spring. The main extension direction of the clamping spring may be defined by the area of the clamping spring situated in the insertion guide channel between the root area and the supporting section of the sheet metal part. However, it is also conceivable that the main extension direction of the clamping spring is defined exclusively by the area of the clamping spring delimited by the side web and the supporting section of the sheet metal part in the insertion guide channel. 
     The sheet metal part can be provided with two arches in the root area. These two arches may abut each other and be formed counter to each other, i.e. in the shape of an S. This intensifies the elastic effect of the clamping spring. The second arch may abut the first arch essentially in the direction of the clamping end of the clamping spring. In the main extension direction of the clamping spring, a kind of parallelism of the course of the clamping spring occurs with respect to the transverse web or the surface of the transverse web facing the conductor insertion area, due to this S-shaped design. The course of the main extension direction of the clamping spring is essentially located in the insertion guide channel, i.e. in the area between the supporting section and the side web or the root area of the clamping spring. 
     The first arch and the second arch may thus be designed in such a way that, in the non-deflected state of the clamping spring, the main extension direction of the clamping spring is oriented in parallel, i.e. approximately in parallel +/−10°, to the surface of a transverse web of the sheet metal part abutting the root area or to the transverse orientation of the transverse web at right angles to the longitudinal extension direction of the transverse web or the lined-up direction of the clamping springs. 
     The groove of the first arch may be situated on the side of the sheet metal part which is opposite the side of the sheet metal part from which the clamping spring protrudes. 
     The at least one clamping spring may be formed as a single piece from the material of the sheet metal part. The clamping spring is then released from the sheet metal part (e.g. cut out or stamped out) and is bent away from the plane of the sheet metal part. An opening is then present in the plane of the sheet metal part. This opening is the window that remains due to the removal of the clamping spring from the sheet metal part and which is delimited by two side webs. 
     In this way, a highly material-conserving conductor terminal may be provided, in which the sheet metal part, together with the clamping spring formed therefrom, contributes to the spring-elastic clamping of an electric conductor. 
     The sheet metal part may carry an electrically conductive busbar opposite the free end of the clamping spring. The provision of a separate busbar of this type, on which the electric conductor rests and is clamped due to the spring force of the clamping spring, has the advantage that an improved current transfer may be ensured by selecting another electrically conductive material, e.g. having a higher copper content. Alternatively, the clamping point may also be formed between the clamping spring and a web of the sheet metal part opposite the clamping spring. 
     The conductor terminal may have an insulating material housing comprising a housing part, in which the sheet metal part is accommodated. The housing part is then closed by a cover part, which may engage, for example, with the housing part. The cover part then has at least one insertion guide channel leading to a particular clamping spring. 
     The channel side walls can be formed on a cover part. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes, combinations, and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein: 
         FIG. 1  shows a sectional side view of an embodiment of a conductor terminal; 
         FIG. 2  shows the sectional side view from  FIG. 1 , including a clamped electric conductor; 
         FIG. 3  shows a sectional side view of a contact element for the terminal conductor from  FIGS. 1 and 2 ; 
         FIG. 4  shows a sectional side view of an embodiment of the conductor terminal; 
         FIG. 5  shows a perspective view of the contact element from  FIG. 3 ; 
         FIG. 6  shows a perspective view of the cover part of the conductor terminal from  FIGS. 1, 2 and 4 ; 
         FIG. 7  shows a perspective front view of the housing part for the conductor terminal; 
         FIG. 8  shows a perspective rear view of the housing part of the conductor terminal; 
         FIG. 9  shows a longitudinal sectional view of the housing part from  FIG. 7 ; 
         FIG. 10  shows a longitudinal sectional view of the cover part from  FIG. 6 ; 
         FIG. 11  shows a front view of the cover part from  FIG. 6 ; 
         FIG. 12  shows a top view of the sheet metal part of the contact element from  FIG. 5 ; 
         FIG. 13  shows a perspective view of an embodiment of a contact element for a two-row conductor terminal; 
         FIG. 14  shows a side view of the contact part from  FIG. 13 ; 
         FIG. 15  shows a front view of the contact part from  FIGS. 13 and 14 ; 
         FIG. 16  shows a sectional side view of a two-row embodiment of the conductor terminal, including the contact part from  FIGS. 13 through 15 ; 
         FIG. 17  shows a perspective rear side view of the conductor terminal from  FIG. 16 ; 
         FIG. 18  shows a front view of the conductor terminal from  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a sectional side view of a first, single-row conductor terminal  1  for clamping electric conductors. Conductor terminal  1  has an insulating material housing  2 , which is formed from a housing part  3  and a cover part  4 , which closes housing part  3  on the front side. Cover part  4  is inserted into housing part  3  and is engaged therewith. A contact element  5 , which has a sheet metal part  6  and a busbar  7 , is introduced into housing part  3 . Sheet metal part  6  has a clamping spring  8 , which is released from sheet metal part  6  (e.g. cut out or stamped out) and is bent away from the plane of sheet metal part  6 . By bending away clamping spring  8 , an opening delimited by side webs  9  remains in sheet metal part  6 . The freely movable end of clamping spring  8  forms a clamping end, which rests upon busbar  7 , e.g. in the unoccupied idle state, and together with busbar  7  forms a clamping point for clamping an electric conductor clamped between clamping end  10  and busbar  7 . 
     It is clear that the sheet metal part is bent in the shape of a U and has a supporting section  11  for busbar  7  adjacent to clamping end  10 . 
     Cover part  4  has an insertion guide channel  12 , which is delimited by channel side walls  13 . Channel side walls  13  of cover part  4  extend laterally beyond clamping spring  8  into the opening of sheet metal part  6 . Channel side walls  13  may project behind sheet metal part  6  in conductor insertion direction L and protrude into a conductor capture pocket  14 . However, they may also end at side webs  9  of sheet metal part  6 . In this way, a lateral guidance of an electric conductor to be clamped beyond the clamping point is provided. In addition, clamping spring  8  is centered and laterally guided. 
     Conductor terminal  1  from  FIG. 1  is now apparent in  FIG. 2 , in this case including an inserted and clamped electric conductor  15 . This electric conductor  15  has an insulating material sheath  16 , which surrounds electrically conductive conductor core  17 . The stripped end of electric conductor  15  is guided through the opening delimited by side webs  9  of sheet metal part  6  laterally along channel side walls  13  and dips into conductor capture pocket  14 . It is apparent that clamping spring  8  is now displaced away from busbar  7  and rests with its clamping edge  10  on electric conductor  15 . Electric conductor  15  rests with its stripped end on the side of busbar  7  which is diametrically opposed to clamping edge  10 . Electric conductor  15  is pressed against busbar  7  by the spring force of clamping spring  8 , and electric conductor  15  is prevented from being pulled out by sharp-edged clamping edge  10  of clamping spring  8 . 
     It is clear that clamping spring  8  has a convex arch in root area  18 , i.e. in the transition to frame-like sheet metal part  6 , in this clamping position of busbar  7 . Root area  18  having this arched section greatly contributes to the spring elasticity and to the application of the necessary spring force. 
     Compared to  FIG. 1 , it is also clear that sheet metal part  6  with its root area  18  is bent slightly farther away from opposite busbar  7 . Root area  18 , including abutting side webs  9 , also noticeably contributes to the spring elasticity. 
     Opposite root area  18 , sheet metal part  6  is folded over with two bends spaced a distance apart in such a way that side webs  9 , which delimit the opening, extend transversely (90 degrees+/−10 degrees) to the longitudinal extension direction of clamped electric conductor  15 . Clamping end  10  of clamping spring  8  moves out of the idle position ( FIG. 1 ) into the clamping position ( FIG. 2 ) upstream from this horizontal section of side webs  9 , viewed in conductor insertion direction L. 
     It is also clear that clamping spring  8  extends in a main extension direction H, which is defined by the middle orientation of clamping spring  8  in insertion guide channel  12  in the area of clamping spring  8  delimited by side web  9  and supporting section  11  of sheet metal part  6 . 
       FIG. 3  shows a sectional side view of sheet metal part  6 . Clamping spring  8  is in the idle state, in which sharp-edged clamping end  10  rests on supporting section  11 . 
     It is clear that sheet metal part  6  is arched in root area  18 , i.e. in the transition from transverse web  20  to clamping spring  8 . This arch is S-shaped, i.e. it is made up of first arch  29  and a second arch  30 , which is formed in the opposite direction. At least one of these arches  29 ,  30  has a groove  19 , whose groove base is oriented transversely to main extension direction H of clamping spring  8 . First arch  29  is not only present on clamping spring  8  but also on adjacent side webs  9 . A third arch  40  is present in the transition between transverse web  20  and side webs  9 . First and third arches  29 ,  40  are also S-shaped, i.e. oriented in opposite directions from each other. 
     Clamping spring  8  is first bent in root area  18  at angle α in the idle state, starting from clamping end  10 , and then bent at angle ß. These two bending radii a and ß are different. Angle α may have, for example, an angle in the area of 38 degrees+/−2 degrees, and angle ß may have an angle of 41.5 Grad+/−1 degree. 
     Adjacent to clamping spring  8 , side web  9  is first bent downward once in the direction of the plane of support leg  11  and then curved. This curvature angle may be greater than 90 degrees and should be in the area of approximately 120 degrees+/−20 degrees. 
     When releasing clamping spring  8  (e.g. spring tongue), for example by stamping, the necessary stabilization of clamping spring  8  in root area  18  is achieved by this described arch. Bending clamping spring  8  back at illustrated bending angles α, ß results in an elastic predeformation, which improves the spring forces of clamping spring  8  and makes it possible to shorten clamping spring  8 . This makes it possible to implement a conductor terminal  1  having a very low height. In addition, an inserted electric conductor  15  strikes clamping spring  8  only in a released area of sheet metal part  6  through a slit in remaining sheet metal part  6 , the clamping spring then yielding in a spring-elastic manner upon the striking of inserted electric conductor  15 . 
     It is furthermore apparent that transverse web  20  of sheet metal part  6  abutting root area  18  is inclined at an angle γ with respect to the plane of supporting section  11 . This angle γ may be in the area of, for example, 38 degrees+/−2 degrees. 
     Transverse web  20  has a surface  41 , which faces insertion guide channel  12 . Surface  41  and main extension direction H of clamping spring  8  have an approximately parallel position with respect to each other. The transverse direction of transverse web  20  at right angles to its longitudinal extension direction and the main extension direction are essentially in parallel to each other. 
     It is furthermore apparent that main extension direction H of clamping spring  8  is situated between root area  18  and supporting section  11  of sheet metal part  6  in the area of insertion guide channel  12 , i.e. of the conductor receptacle. 
     A second specific embodiment of conductor terminal  1  is apparent in  FIG. 4 . Reference may essentially be made to the description of the first exemplary embodiment. In contrast thereto, contact element  5 , however, includes only sheet metal part  6  without a separate additional busbar  7 . Electric conductor  15  is clamped to supporting section  11  of sheet metal part  6  with the aid of clamping spring  8 . 
     A perspective view of sheet metal part  6  of conductor terminals  1  described above is apparent in  FIG. 5 . It is clear that multiple clamping springs  8 , situated side by side, are released from sheet metal part  6  and are bent away from the plane adjacent to particular root area  18  and spanned by side webs  9  toward opposite supporting section  11 . It is clear that side webs  9  remaining due to the release of clamping spring  8  delimit an opening  21 . Side webs  9  are bent at right angles to the plane of side webs  9  adjacent to root area  18  and then folded back against conductor insertion direction L together with supporting section  11 . Clamping spring  8  (clamping tongue) is movable within a range, viewed in conductor insertion direction L, in front of the plane spanned by the vertical sections of side webs  9 . 
     It is furthermore clear that supporting section  11  has a protruding nose  22  (material tab) behind particular clamping end  10  of clamping spring  8 , viewed in conductor insertion direction L, on which busbar  7  may be supported. Busbar  7  may be held in a form-fitting manner in the intermediate space between these noses  22  and side webs  9 . 
       FIG. 6  shows a perspective view of cover part  4 , including channel side walls  13 , which laterally delimit a particular insertion guide channel  12 . It is clear that two adjacent channel side walls  13  of insertion guide channels  12  arranged side by side are each connected to each other by a connecting web  23 . Connecting web  23  then ends before narrower lugs  24 , which are inserted into an opening in sheet metal part  6  delimited by a side web  9 . Webs  9  are then positioned between lugs  24  connected to each other by connecting web  23  of cover part  4 . 
     This cover part  4  is formed from a plastic material made from insulating material and has suitable latching elements for latching cover part  4  to housing part  3 . It is clear that the two outer channel side walls  13  are T-shaped in cross section. The intermediate pairs of channel side walls  13 , including connecting webs  23 , are H-shaped, i.e. double T-shaped, in cross section. The observed cross section is in the main area behind lugs  24 . 
       FIG. 7  shows a perspective front view of housing part  3  of single-row conductor terminal  1 . It is clear that latching protrusions  25  are present on the inside of housing part  3 , which are used to latch cover part  4 . Latching tabs  26  also project from the end face of housing part  3 , which dip into the corresponding latching opening of cover part  4 . The contact element formed from sheet metal part  6  illustrated in  FIG. 5  and possibly a busbar  7 , is inserted into the interior of housing part  3 . Housing part  3  is then closed by cover part  4  illustrated in  FIG. 6 . 
       FIG. 8  shows a perspective rear side view of housing part  3  from  FIG. 7 . It is clear that a test opening  27  is present on the back of housing part  3 , which leads to side webs  9  of sheet metal part  6 . The electrical potential present at the contact element may be measured by inserting an electrically conductive test tool. 
       FIG. 9  shows a longitudinal sectional view of housing part  3 , viewed from above. It is clear that housing part  3  has multiple conductor capture pockets in the rear area, which are arranged side by side. Test opening  27 , which leads into the interior of housing part  3 , is also apparent. 
       FIG. 10  shows a longitudinal sectional view of cover part  4 , viewed from above. It is clear that insertion guide channels  12  extend from the front side to the end of cover part  4 . Insertion guide channels  12  first have an expanded section and then transition into a tapered section in a conically tapered manner. Insertion guide channels  12  are delimited by channel side walls  13 , which extend farther beyond the conically tapering part and end in narrower lugs  24 . The material thickness of channel side walls  13  expands from lugs  14  to the front side. Diametrically opposed channel side walls  13  of adjacent insertion guide channels  12  are each connected to each other to form a single piece by connecting webs  23 . Since connecting web  23  and channel side walls  13  are formed from the same insulating material, channel side walls  13  and connecting webs  23  do not appear to be separate in the sectional representation but are visible as a widened section, including the channel side walls, on the opposite surfaces of this material section. 
       FIG. 11  shows a front view of cover part  4  with a view of insertion guide channels  12 . It is clear that, in this cover part  4  for a three-pole conductor terminal  3 , insertion guide channels  12  are arranged side by side and spaced a distance apart by channel side walls  13  with connecting web  23 . Each insertion guide channel  12  leads to a clamping point formed by a clamping spring  8  and shared busbar  7  extending transversely to the extension direction of insertion guide channels  12  for the purpose of clamping an electric conductor  15  inserted into a particular insertion guide channel  12 . 
       FIG. 12  shows a top view of sheet metal part  6  of conductor terminals  1  described above. It is clear that clamping springs  8  are cut out of sheet metal part  6 , forming clamping tongues, while side webs  9  remain. These side webs  9  are connected to each other in the root area via a shared transverse web  28 , so that sheet metal part  6  has a frame-like structure. 
     It is also clear that side webs  9  are folded upward at right angles in a vertical section and transition into supporting section  11 . This supporting section  11  also includes a transverse web connecting side webs  9 , on which noses  22  between side webs  9  are optionally arranged in particular opening  21 . 
       FIG. 13  shows another specific embodiment of a sheet metal part  36  for a two-row conductor terminal  31 . Reference may essentially be made to the embodiments discussed above. In this specific embodiment, however, supporting section  11  is arranged in the plane of vertical opening  21  or vertical section of side webs  9  and connects two groups of clamping springs  8 , which are connected to each other by a particular transverse web  28  and are arranged to mirror each other. Clamping tongues  8  of opposite groups of clamping springs  8  protrude diagonally toward each other and are oriented in the direction of supporting section  11 . 
     The arch illustrated in  FIG. 3  is present on both sides. 
       FIG. 14  shows a side view of sheet metal part  36  from  FIG. 13 . It is clear that in each case two clamping springs  8  are arranged one above the other and oriented toward central supporting section  11  in the vertical section of sheet metal part  36 . 
       FIG. 15  shows a view of sheet meta part  36  in  FIGS. 13 and 14  with a view of central supporting section  11 . It is very clearly apparent that clamping end  10  of clamping springs  8  is arranged at an obtuse angle in a centrally tapering manner. Clamping end  10  of clamping spring  8  thus does not have a straight clamping edge but rather a triangular clamping edge. If an attempt is made to twist out a clamped electric conductor, the latter then slides onto one or the other edge sides of the clamping end, depending on the rotation direction, so that spiral shape tending to lead in the conductor insertion direction results. It is thus difficult to twist out an electric conductor. This specific embodiment of clamping end  10  may be used for each conductor terminal  1 ,  31  regardless of the number of poles and also regardless of the design of contact element  5  and insulating material housing  2 ,  32 . 
     It is also clear that two rows of spring clamping connections for electric conductors  15  are provided by opposite clamping springs  8 . 
       FIG. 16  shows a sectional side view of a two-row conductor terminal  31  of this type. Insulating material housing  32 , in turn, has a two-part design, comprising a housing part  33  and a cover part  34 . It is now approximately twice the height of the single-row specific embodiment. It is clear that cover part  34  has two insertion guide channels  12  disposed one above the other and, depending on the number of poles, multiple such side-by-side pairs of insertion guide channels  12 . 
     Channel side walls  13  are again present on cover part  34 , which project through the opening in sheet metal part  6 . 
     It is furthermore apparent that busbar  37  in the illustrated exemplary embodiments of a two-row conductor terminal  31  is no longer plate-shaped but is designed as a sheet metal part bent into the shape of a U. This busbar  37  is then built into vertical supporting section  11  in such a way that supporting section  11 , including material tabs  22 , is surrounded on both sides by busbar  37 . 
       FIG. 17  shows a rear view of two-row conductor terminal  31  from  FIG. 16 . It is clear that once again a test opening  27  is present in housing part  33 , which leads to sheet metal part  36 . 
       FIG. 18  shows a front view of two-row conductor terminal  31  from  FIG. 16 . It is apparent that multiple insertion guide channels  12  are introduced into cover part  34  consecutively in a row and two such rows of insertion guide channels are introduced therein one above the other. As a result, a six-pole conductor terminal  31 , for example, is provided. 
     However, variants of two-pole, four-pole, eight-pole etc. conductor terminals are also conceivable, i.e. conductor terminals having other integral numbers of poles. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims