Patent Publication Number: US-11394132-B2

Title: Cable assembly

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority under 35 U.S.C. § 119 from Japanese Patent Application No. 2020-105749 filed on Jun. 19, 2020, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present application relates to a cable assembly of a shield connector such as a high-speed transmission connector. 
     BACKGROUND 
     Japanese Patent Application Publication No. 2018-63795 discloses a shielded twisted pair (STP) connector as a shield connector provided with a shielded twisted pair cable. 
     SUMMARY 
     However, in the case of the STP connector disclosed in Japanese Patent Application Publication No. 2018-63795, when a tensile force is applied in a direction in which the STP cable is relatively separated from the outer conductor, there is a possibility that a shield conductor such as a braided wire is misaligned from a barrel portion, and in the worst case, the shield conductor may fall out from the barrel portion. Therefore, there is a concern that the electrical connection reliability between the outer conductor and the shield conductor such as a braided wire in the STP cable may be reduced due to misalignment. 
     An object of the present application is to provide a cable assembly with high electrical connection reliability capable of preventing a cable from relatively separating from a shield terminal even when a tensile force is applied in a direction in which the cable is relatively separated from the shield terminal. 
     According an embodiment of the present application, a cable assembly comprises a shield terminal including a braided crimping piece and a sheath crimping piece, a cable including a braid and a sheath, and a sleeve attached to an outer periphery of the braid. In the cable assembly, the sleeve is disposed on the outer periphery of the braid by crimping, the braid is folded back at a front end side of the sleeve by a folding-back portion, the braid folded back by the folding-back portion covers an outer periphery of the sleeve, the braided crimping piece of the shield terminal is crimped to the outer periphery of the sleeve via the braid folded back by the folding-back portion, and the braid folded back by the folding-back portion is held between the sleeve and the braided crimping piece, a sheath crimping piece of the shield terminal is crimped to an outer periphery of the sheath of the cable, and when a tensile force is applied in a direction in which the cable is relatively separated from the shield terminal, the sleeve is moved in a tensile direction, so that a rear end edge of the sleeve and a front end edge of the sheath crimping piece are brought into abutment with each other. 
     It is preferable that the sheath crimping piece is crimped to the outer periphery of the sheath such that an inner diameter of the braid in a crimped portion of the sheath crimping piece is the same or substantially the same as an inner diameter of the braid in an uncrimped portion of the sheath. 
     It is preferable that the sleeve is formed in a C-shaped plate, and the C-shaped sleeve is cylindrically crimped to the outer periphery of the braid. 
     It is preferable that the sleeve includes an engagement recess at one end side and an engagement protrusion at the other end side, and the engagement protrusion is fitted into the engagement recess when the sleeve is crimped to the outer periphery of the braid. 
     It is preferable that the cable assembly further comprises an inner housing to which a terminal connected to an exposed internal wire is attached to an end of the cable and a matching member for impedance adjustment having an insertion hole into which the internal wire is inserted, and the inner housing and the matching member are integrally housed in a shield connecting portion of the shield terminal. 
     According to the above configuration, it is possible to provide a cable assembly with high electrical connection reliability capable of preventing a cable from relatively separating from a shield terminal even when a tensile force is applied in a direction in which the cable is relatively separated from the shield terminal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing an example of a shield connector using a cable assembly according to an embodiment of the present application. 
         FIG. 2  is an exploded perspective view of the cable assembly. 
         FIG. 3  is a perspective view showing a state before assembling an inner housing and a matching member of the cable assembly. 
         FIG. 4  is a perspective view showing a state before assembling a terminal to an end of a cable of the cable assembly. 
         FIG. 5  is a front view of the cable assembly. 
         FIG. 6  is a cross-sectional view taken along line VI-VI in  FIG. 5 . 
         FIG. 7  is a cross-sectional view taken along line VII-VII in  FIG. 5 . 
         FIG. 8  is an enlarged cross-sectional view of a main portion of the cable assembly. 
     
    
    
     DETAILED DESCRIPTION 
     A cable assembly according to an embodiment of the present application will be described in detail below with reference to the drawings. 
     As shown in  FIG. 1 , a shield connector  1  includes a cable assembly  2  for high-speed transmission and connected to an end of a shielded twisted pair (STP) electric wire which is a cable  10 , and an outer housing  3  for housing the cable assembly  2 . That is, the shield connector  1  is a high-speed transmission connector for differential communication and has an electromagnetic shield structure. 
     As shown in  FIG. 1 , an outer housing  3  is formed in a box shape made of resin and includes an assembly housing portion  3   a  for housing the cable assembly  2 . A lock arm  3   c , which maintains a fitting state when the outer housing  3  is fitted to a mating connector (not shown), is provided on an upper surface  3   b  side of the outer housing  3 . 
     As shown in  FIGS. 1 and 2 , the cable assembly  2  includes a cable  10 , a metal female terminal (terminal)  15 , a sleeve  16 , a shield terminal  17 , an inner housing  18 , and a matching member for impedance adjustment  19  as component elements. 
     As shown in  FIGS. 2, 4, and 7 , the cable  10  includes two twisted internal wires  11 , a metal braid  13  covering the two internal wires  11  via a shield foil  12 , and a sheath  14 , which is a resin outer coating, for covering the braid  13 . Each internal wire  11  includes a metal core wire  11   a  and a resin insulating film  11   b  covering the core wire  11   a . The two internal wires  11  exposed on the end  10   a  side of the cable  10  are untwisted, and a pair of core wire crimping pieces  15   b  of a female terminal  15  are crimp-connected to the core wire  11   a  exposed from the respective insulating films  11   b . The female terminal  15  includes a contact portion  15   a  to which a tab of a male terminal of a mating connector (not shown) is electrically connected to the front side of the pair of core wire crimping pieces  15   b . In the female terminal  15  shown in  FIGS. 2 and 4 , the pair of core wire crimping pieces  15   b  are shown in a crimped shape. 
     As shown in  FIGS. 2 and 4 , a sleeve  16  is made of metal and formed in a C-shaped plate before being crimped, and is attached to an outer periphery of the braid  13  where a part of a sheath  14  of the cable  10  is cut off and exposed. The C-shaped sleeve  16  includes a plurality of protrusions  16   a  at the center, an engagement recess  16   b  at one end, and an engagement protrusion  16   c  at the other end. As shown in  FIGS. 6 and 8 , when a braided crimping piece  17   b  of a shield terminal  17  to be described later is crimped to a folded-back braid  13 A of the cable  10 , the folded-back braid  13 A is disposed at a position adjacent to a front end edge  17   d  of a sheath crimping piece  17   c  from the front side in the braided crimping piece  17   b . That is, as shown in  FIGS. 4 and 7 , the C-shaped sleeve  16  is disposed on the outer periphery of the braid  13  by being crimped in a cylindrical shape, while being covered with the folded-back braid  13 A with the engagement protrusion  16   c  fitted into the engagement recess  16   b . That is, as shown in  FIGS. 6 to 8 , the braid  13  is folded back toward a rear end edge  16   e  side by a folding-back portion  13   a  at a front end  16   d  of the sleeve  16  which is crimped in a cylindrical shape, and the braid  13 A folded back at the folding-back portion  13   a  covers an outer periphery of the cylindrical sleeve  16 . 
     As shown in  FIG. 2 , the shield terminal  17  is formed by sheet metal working using a sheet metal material. The shield terminal  17  includes a cylindrical housing portion  17   a , serving as a shield connecting portion, for housing an inner housing  18  and a matching member  19 . The shield terminal  17  includes a pair of braided crimping pieces  17   b  for crimping and connecting the braid  13  exposed by cutting off a part of the sheath  14  of the cable  10 , and a pair of sheath crimping pieces  17   c  for crimping and connecting the sheath  14  of the cable  10 . As shown in  FIG. 6 , the braided crimping piece  17   b  of the shield terminal  17  crimps the sleeve  16  crimped to the outer periphery of the braid  13  exposed from the sheath  14 , while crimping and connecting the braid  13 A folded back by the folding-back portion  13   a  covering the outer periphery of the sleeve  16 . That is, the braided crimping piece  17   b  is crimped to the outer periphery of the sleeve  16  via the braid  13 A folded back by the folding-back portion  13   a . The braid  13 A folded back by the folding-back portion  13   a  is held by the sleeve  16  and the braid crimping piece  17   b , and the shield terminal  17  and the braid  13  are electrically connected. 
     When the crimping connection between the cable  10  and the shield terminal  17  is described in detail, as shown in  FIGS. 6 to 8 , the sheath crimping piece  17   c  of the shield terminal  17  is crimped to the outer periphery of the sheath  14  of the cable  10 . The cable  10  is held (fixed) to the shield terminal  17  by crimping the braided crimping piece  17   b  to the sleeve  16  via the braid  13 A folded back at the folding-back portion  13   a  and further crimping the sheath crimping piece  17   c  to the sheath  14 . In this case, as shown in  FIGS. 6 and 8 , the rear end edge  16   e  of the sleeve  16  and the front end edge  17   d  of the sheath crimping piece  17   c  are adjacent to each other. That is, there is some clearance t in the axial direction between the rear end edge  16   e  of the sleeve  16  and the front end edge  17   d  of the sheath crimping piece  17   c . In the shield terminal  17  shown in  FIG. 2 , the pair of braided crimping pieces  17   b  and the pair of sheath crimping pieces  17   c  are shown in a crimped shape. 
     As shown in  FIG. 2 ,  FIG. 3 , and  FIG. 6 , an inner housing  18  is formed of synthetic resin in an elliptical cylindrical shape, and includes a pair of right and left terminal housing chambers  18   a  on both sides of the inner housing  18 . Each female terminal  15 , which is connected to the end of the cable  10 , is inserted into the pair of right and left terminal housing chambers  18   a . The female terminal  15  housed in the respective terminal housing chambers  18   a  is held by locking means (not shown). In the center of the rear side of an upper surface  18   b  and a lower surface  18   c  of the inner housing  18 , an engagement groove (engagement recess)  18   d  into which a pair of engagement protrusions  19   b  and  19   b  of the resin matching member  19 , which will be described later, are press-fitted is formed. 
     As shown in  FIGS. 6 and 7 , the matching member  19  is a dielectric for impedance adjustment, and is interposed between the inner housing  18  and the sleeve  16  to suppress impedance mismatch and improve the transmission performance of the cable assembly  2  of the shield connector  1 . As shown in  FIGS. 2 and 3 , the matching member  19  for impedance adjustment is formed in a resin cylindrical shape having a pair of insertion holes  19   a  into which untwisted portions of the internal wires  11  crimp-connected to the two female terminals  15  are inserted. Further, at the front of the center of the upper and lower portions, the matching member  19  is provided with an engagement protrusion (engagement portion)  19   b  which is press-fitted into the upper and lower engagement grooves  18   d  of the inner housing  19 . The engagement groove  18   d  and the engagement protrusion  19   b  constitute engagement means for integrating the inner housing  18  and the matching member  19 . As shown in  FIG. 7 , in the cylindrical housing portion  17   a  of the shield terminal  17 , the integrated inner housing  18  and the matching member  19  are housed, and are held by locking means including a locking piece portion  17   e  and a locking recess portion  19   d . Instead of the matching member  19  which is a dielectric, a metallic member which is a conductor may be used. 
     Next, the assembling procedure of each component constituting the cable assembly  2  described above will be described. 
     First, a part of the sheath  14  of the end  10   a  of the cable  10  is cut off to expose the braid  13 , and the sleeve  16  is cylindrically crimped to the outer periphery of the exposed braid  13 . As shown in  FIG. 4 , an end portion of the braid  13  is folded back toward the rear end edge  16   e  so that the braid  13 A folded back at the folding-back portion  13   a  of the braid  13  covers the outer periphery of the cylindrical sleeve  16 . 
     Next, the core wire crimping piece  15   b  of the female terminal  15  is crimp-connected to the core wire  11   a  exposed from each insulating film  11   b  of the two internal wires  11  exposed to the end  10   a  side of the cable  10 . Thereafter, the two female terminals  15  and  15  are inserted into the pair of insertion holes  19   a  of the matching member  19  for impedance adjustment and housed in the pair of terminal housing chambers  18   a  of the inner housing  18 . 
     Then, the engagement protrusion  19   b  of the matching member  19  is press-fitted and held in the engagement groove  18   d  of the inner housing  18 , and the inner housing  18  integrated with the matching member  19  is housed in the housing portion  17   a  of the shield terminal  17 . Thereafter, the braided crimping piece  17   b  of the shield terminal  17  is crimped to the braid  13 A folded back at the folding-back portion  13   a  of the braid  13  of the cable  10 , and the sheath crimping piece  17   c  is crimped to the sheath  14  of the cable  10  to complete the cable assembly  2  shown in  FIGS. 1 and 6 . 
     According to the cable assembly  2  of the above embodiment, as shown in  FIG. 6 , even if a tensile force is applied in the direction P in which the cable  10  is separated from the shield terminal  17 , the cable  10  is prevented from being separated from the sheath crimping piece  17   c  of the shield terminal  17 . 
     Specifically, as shown in  FIG. 6 , when the cable assembly  2  is conveyed or mounted on a vehicle as a shield connector  1  for a high-speed transmission connector, a tensile force may be applied in the direction P in which the cable  10  is relatively separated from the shield terminal  17 . In this case, when the sleeve  16  moves in the tensile direction P, the rear end edge  16   e  of the sleeve  16  and the front end edge  17   d  of the sheath crimping piece  17   c  of the shield terminal  17  are brought into abutment with each other. This abutment occurs when the cable  10  is pulled, the folding-back portion  13   a  of the braid  13  pushes the rear end of the sleeve  16  in the tensile direction P, and the sleeve  16  is displaced in the tensile direction P. By crimping the braided crimping piece  17   b  to the sleeve  16  via the folded-back braid  13 A and crimping the sheath crimping piece  17   c  to the sheath  14 , the cable  10  is fixed to the shield terminal  17  to secure a holding force of the cable  10 . Therefore, even if a tensile force is applied to the cable  10  by the abutment, the cable  10  can be prevented from being relatively separated (misaligned) from the shield terminal  17 . As a result, the electrical connection reliability between the shield terminal  17  and the braid  13  in the cable  10  is prevented from being deteriorated due to misalignment, thereby enhancing the electrical connection reliability. Further, since the misalignment is prevented, the holding force of the cable  10  of the cable assembly  2  is also improved. 
     In this way, in the cable assembly  2 , when a tensile force is applied to the cable  10 , the rear end edge  16   e  of the sleeve  16  and the front end edge  17   d  of the sheath crimping piece  17   c  of the shield terminal  17  are brought into abutment with each other, whereby the holding force of the cable  10  is further secured. 
     As shown in  FIG. 8 , in the crimped state of the sheath  14  in the sheath crimping piece  17   c , an inner diameter B of the braid  13  in the crimped portion of the sheath crimping piece  17   c  is the same as an inner diameter A of the braid  13  in the uncrimped portion of the sheath  14 . Alternatively, the sheath crimping piece  17   c  is crimped to the outer periphery of the sheath  14  so as to be substantially equivalent. That is, the sheath crimping piece  17   c  is crimped to the outer periphery of the sheath  14  so as to be “inner diameter B of the braid  13 =inner diameter A of the braid  13  or inner diameter B of the braid  13 ≈inner diameter A of the braid  13 ”. Further, as the crimping amount of the sheath crimping piece  17   c  is increased, the inner diameter B of the braid  13  becomes smaller and the holding force becomes higher, but “inner diameter B of the braid  13 &lt;inner diameter A of the braid  13 ”, so that the impedance of the cable  10  is mismatched in the axial direction. However, since in the cable assembly  2 , the fact is that “inner diameter B of the braid  13 =inner diameter A of the braid  13  or inner diameter B of the braid  13 ≈inner diameter A of the braid  13 ”, it is possible to prevent the impedance from being mismatched while securing the holding force of the cable  10 . 
     Next, a comparative example of the present application will be described. A shielded twisted pair (STP) connector according to a comparative example of the present application is provided with an outer conductor (shield terminal) in an STP dielectric. In the outer conductor, a shield conductor such as a braided wire which surrounds and shields a pair of twisted wires of the STP cable is crimped and crimp-connected at a barrel portion. 
     However, in the STP connector according to the comparative example, when a tensile force is applied in a direction in which the STP cable is relatively separated from the outer conductor, the shield conductor such as the braided wire may be misaligned from the barrel portion, and in the worst case, the shield conductor may be removed from the barrel portion. Therefore, there is a concern that the electrical connection reliability between the outer conductor and the shield conductor such as the braided wire in the STP cable may be reduced due to misalignment. 
     Although the present embodiment of the present application has been described above, the present embodiment is not limited thereto, and various modifications can be made within the scope of the gist of the present embodiment. 
     That is, according to the present embodiment, the sleeve has a C-shaped plate before being crimped and is formed in a cylindrical shape after being crimped, but may have a cylindrical shape before being crimped. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.