Patent Publication Number: US-8969725-B2

Title: Shielded cable

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to Application No. 11 003 845.2, filed in the European Patent Office on May 11, 2011, which is expressly incorporated herein in its entirety by reference thereto. 
     FIELD OF THE INVENTION 
     The present invention relates to a preassembled cable, which, for example, includes a plug connector for transmitting HF signals. 
     BACKGROUND INFORMATION 
     Such cables can be used in motor vehicles or aircrafts, for example, and are frequently required in large quantities. Simple construction and simple preassembly are important factors in the economic supply of corresponding cables. In addition, such cables must have excellent electromagnetic shielding in order to ensure that radiated electromagnetic waves do not cause problems in the onboard electronics of the vehicle. Furthermore, such cables must be produced such that they can be used to transmit signals having very high frequencies, as required for a high-quality video signal transmission, for example. 
     A cable with a shielded design is described in German Published Patent Application No. 10 2007 047 436. A crimp connection is provided such that it has a so-called center recess. 
     European Published Patent Application No. 0 328 234 describes a shielded cable, which features a crimp connection between a sleeve and a shield that is said to be suitable for high electromagnetic shielding. 
     SUMMARY 
     Example embodiments of the present invention provide a cable that has excellent shielding, so that the radiated electromagnetic output is minimized, that is to say, high EMC impermeability is ensured. Nevertheless, the cable should also be able to be manufactured at relatively low production cost. 
     According to example embodiments of the present invention, the cable for the transmission of HF signals includes a shield, at least one wire and an electrically conductive sleeve. The sleeve in turn has a longitudinal axis and, viewed geometrically, is subdividable into a first geometrical sleeve half and a second geometrical sleeve half, by a longitudinal cross-sectional plane. In addition, the sleeve has a first section and a second section, which are disposed at a mutual offset in the direction of the longitudinal axis. The sleeve also encloses the shield and is connected to the shield by a crimp connection. The crimping is provided such that the sleeve has at least one crimp ridge within the first section in the first sleeve half and does not have a ridge in the second sleeve half. At the same time, the sleeve is provided without crimp ridge within the second section in the first sleeve half and has at least one crimp ridge in the second sleeve half. 
     A sleeve half provided without crimp ridges in certain sections, for example, denotes that the particular axial section of the sleeve half has an uninterrupted concave configuration on the inside, so that uniform press-fitting of the shield takes place there such that it largely extends without geometrical interruptions. The mere existence of press-fitting marks on the outside of the sleeve thus cannot establish that the particular region of the sleeve is to be considered free of crimp ridges. 
     HF signals denote signals produced with the aid of high frequency technology, including also UHF or VHF signals, for example. Especially digital signals having a transmission rate that is greater than or equal to 10 MBit/s are also among them. 
     The sleeve may have a third section, which is located at an offset in relation to the first and second sections in the direction of the longitudinal axis. The sleeve has at least one crimp ridge within the third section in the first half, and does not have any crimp ridges in the second sleeve half. 
     The sleeve may have at least one crimp ridge within a first cross-section in the first sleeve half, and may have no crimp ridges in the second half, and the sleeve may be without crimp ridges within a second cross-section in the first sleeve half and may have at least one crimp ridge in the second sleeve half. The cross-sections have an orthogonal orientation in relation to the longitudinal axis and are disposed at a mutual offset in the direction of the longitudinal axis. If a third section is present, this, too, may be considered a third cross-section. 
     The axial length of a section results from the length of the crimp ridges, so that a section is as long as its longest crimp ridge. All crimp ridges in a section are usually of equal length. The sections may directly abut each other, so that a crimp ridge in one of the halves is always present across the entire crimp region. 
     The second section of the sleeve may have a smaller diameter than in the first section. In the event that the sleeve also includes a third section, the second section may have the smallest diameter in comparison with the first and third sections. The second section having the smallest diameter may be located between the first and the third section in the direction of the longitudinal axis. 
     The sleeve may have a peripherally closed configuration at least within the sections, i.e., in the crimping region. In other words, there is no opening or slot in the sleeve. As a result, the sleeve completely encloses the shield in the radial direction. 
     The at least one crimp ridge may have a greater axial extension in the first section than the at least one crimp ridge in the second section. 
     The crimp ridges may be set apart from each other about the longitudinal axis, at a center angle that is smaller than 150°, e.g., smaller than 135°. A center angle, for example, denotes a center point angle about a point on the longitudinal axis within the particular section in which the individual crimp ridges are provided. 
     Furthermore, the outside of the sleeve half without crimp ridges may have a continuous convex form in the second section. As an alternative or in addition, the outside of the sleeve half without crimp ridges may have a continuous convex form in the first section. In particular, the sleeve halves without crimp ridges may have a round design on the outside across a center angle of at least 180°. 
     The cable may have four wires which are twisted together. The cable may be configured according to a star quad arrangement, for example. 
     The cable may have an electrically conductive support clamp both in the first and second section, the shield resting against the support clamp radially inside and also radially outside. This bilateral contact may be achieved by folding the shield over prior to the crimping operation. The shield may include a multitude of individual wires so as to form a shield mesh, causing the individual wires to rest against the support clamp both radially inside and radially outside, or to be press-fitted with the support clamp. The sleeve halves without crimp ridges are arranged such that, for example, they have an inner contour that extends substantially parallel to the outer contour of the support clamp. 
     The crimp device for producing a cable includes two crimping indenters. Each of the two crimping indenters is equipped with a crimper and an anvil. The crimper and the anvil of both crimping indenters are disposed at a mutual offset relative to the longitudinal axis. In order to crimp the sleeves, the two crimping indenters are arranged such that they are able to engage with one another, to the effect that a crimper cooperates with an anvil when the crimping indenters are moved relative to each other toward the longitudinal axis of the sleeve. 
     The crimping device may be arranged such that at least one of the crimping indenters includes a saddle for the plastic deformation of the sleeve, its contour extending according to a reference line. A reference line denotes a line along a reference circle, e.g., along an open (not closed) circular line that extends across an angle of less than 360°. 
     In the simplest case, a crimping indenter includes exactly one crimper and one anvil. The crimping device may include two identical crimping indenters. The first crimping indenter may be disposed point-symmetrically in relation to the other crimping indenter, with respect to a point on the longitudinal axis of the sleeve. The two identical crimping indenters in the crimping device thus are able to be used rotated relative to one another about their normal axis. Furthermore, all crimpers of the crimping device and/or all anvils of the crimping device may have the same configuration. 
     The crimping device may include two crimping indenters, one of the crimping indenters having two crimpers and an anvil. As an alternative or in addition, one of the crimping indenters may have one crimper and two anvils. The crimper and anvil of a crimping indenter are arranged at a mutual offset in relation to the longitudinal axis and may engage with one another for crimping purposes or for the press-fitting of the sleeve. 
     One of the crimping indenters may be configured such that an anvil is disposed between two crimpers, or a crimper is disposed between two anvils. The crimping device may include a crimping indenter, in which an anvil is situated between two crimpers, and it includes a crimping indenter in which a crimper is situated between two anvils. The sequence of crimper-anvil along the longitudinal axis is such that a crimper is able to cooperate with an anvil in each case. 
     The crimping device may be configured such that at least one crimping indenter has a configuration in which anvil and crimper constitute different components or different crimping inserts, which are joined to each other in detachable manner, for example. At least one of the anvils or crimpers includes a saddle for the plastic deformation of the sleeve, the contour of which extends parallel to the longitudinal axis across the entire thickness of the component. The different components may have different thicknesses. 
     All components of the crimping device that are used as anvils may be implemented with the same contour as the saddle. In the same manner, all components of the crimping device that are used as crimpers may be implemented with the same contour as the saddle. 
     Example embodiments of the present invention make it possible to increase the conductivity of the crimping connection or to reduce the transition resistance, which results in a better shielding effect. The cables are therefore immune to external electromagnetic radiation and also emit virtually no such radiation. Furthermore, in the production of the cables, the crimping height is able to be adjusted very finely, so that high quality cables are able to be produced with a high degree of reproducibility. 
     Moreover, the crimping connection has extremely high tensile strength between the sleeve and shield. 
     Further features and aspects of example embodiments of the present invention are described in more detail below with reference to the appended Figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view taken along a longitudinal cross-sectional plane through a sleeve for a shielded cable, prior to processing. 
         FIG. 2   a  is a plan view of a first crimp insert pair for producing the shielded cable. 
         FIG. 2   b  is a cross-sectional view of the first crimp insert pair illustrated in  FIG. 2   a , taken along the line Y-Y shown in  FIG. 2   a.    
         FIG. 3   a  is a plan view of a second crimp insert pair for producing the shielded cable. 
         FIG. 3   b  is a cross-sectional view of the second crimp insert pair illustrated in  FIG. 3   a , taken along the line Y-Y shown in  FIG. 3   a.    
         FIG. 4   a  is a plan view of a mounted crimping indenter for producing the shielded cable. 
         FIG. 4   b  is a perspective view of the mounted crimping indenter. 
         FIG. 5  is a lateral view of the end region of the cable. 
         FIG. 6  is an enlarged cross-sectional view of the cable, taken along a cross-sectional plane X-X, shown in  FIG. 5 , through the cable. 
         FIG. 7  is an enlarged detailed view of a sleeve half of the cable. 
         FIG. 8  is an enlarged detail view of the other sleeve half of the cable. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a one-piece electrically conductive sleeve  7 , which is produced by a deep-drawing process and includes a coupling end  7 . 7 , which is suitable for producing a mating connection together with an additional coupling part. Sleeve  7  has a substantially hollow-cylindrical configuration, especially in the particular region provided for later crimping. A longitudinal axis L, which in a first approximation represents an axis of symmetry, may be assigned to sleeve  7 . As for the rest, sleeve  7  has no interruptions, at least in its hollow-cylindrical tubular region, that is to say, it has no slot extending across the entire length of sleeve  7 . Sleeve  7  is provided with an adapter  8  made of plastic, which is situated on sleeve  7  and produced by extrusion coating. The mounting mandrels (not shown in greater detail in the figures) provide for a form-locked, correctly positioned seat between adapter  8  and sleeve  7 . 
     A first crimp insert pair  10 , which includes a crimper  11  and an anvil  12 , is shown in  FIGS. 2   a  and  2   b . Crimper  11  and anvil  12  each have a saddle  11 . 1 ,  12 . 1 , which is provided for the plastic deformation of sleeve  7 . In the exemplary embodiment shown, saddles  11 . 1 ,  12 . 1  have a contour that takes the form of a graduated-circle line. Radius R of the contour, or the graduated-circle line, has identical dimensions for crimper  11  and anvil  12  in the region of saddle  11 . 1 ,  12 . 1 . Crimper  11  also includes two flanks  11 . 2 ,  11 . 3 , which are arranged opposite each other and serve as an infeed region for sleeve  7  to be crimped. As illustrated in  FIG. 2   a , in terms of the sum of the length of the contour of saddle  11 . 1  and flanks  11 . 2  and  11 . 3 , crimper  11  thus has a longer concave contour than anvil  12 , where substantially only the contour of saddle  12 . 1  is present as a concave contour. In the exemplary embodiment shown, crimper  11  and anvil  12  of first crimp insert pair  10  have a thickness D of, e.g., 2 mm. 
       FIGS. 3   a  and  3   b  show a second crimp insert pair  20 . It also includes a crimper  21  and an anvil  22 , each of which has a saddle  21 . 1 ,  22 . 1 . In the region of saddle  21 . 1 ,  22 . 1 , radius r of the contour has the same dimensions for crimper  21  and anvil  22 . Crimp insert pair  20  differs from crimp insert pair  10  illustrated in  FIGS. 2   a ,  2   b , for example, in that radius r is slightly smaller than corresponding radius R in crimp insert pair  10 . In contrast to crimp insert pair  10  illustrated in  FIG. 2   b , crimper  21  and anvil  22  illustrated in  FIG. 3   b  have a thickness d of, e.g., only 1 mm. In terms of the sum of the length of the contour of saddle  21 . 1  and flanks  21 . 2  and  21 . 3 , crimper  11  has a longer concave contour than anvil  22 , where substantially only the contour of saddle  22 . 1  is provided as a concave contour. 
     Furthermore, a third crimp insert pair  30  (see  FIG. 4   b ) may be used in the exemplary embodiment, which also includes a crimper and an anvil  32 . The two crimp insert pairs  10 ,  30  have an identical configuration in the exemplary embodiment shown. Accordingly, the geometry of crimp insert  31  corresponds to the geometry of crimp insert  11  illustrated in  FIGS. 2   a  and  2   b , and the geometry of crimp insert  32  corresponds to the geometry of crimp insert  12  illustrated in  FIGS. 2   a  and  2   b.    
     Saddles  11 . 1 ,  12 . 1 ,  21 . 1 ,  22 . 1  of the six crimp inserts  11 ,  12 ,  21 ,  22 ,  31 ,  32  intended for the plastic deformation of sleeve  7  have a contour that extends parallel to longitudinal axis L across their entire thickness D, d. Accordingly, crimpers  11 ,  21 ,  31  and anvils  12 ,  22 ,  32  have no profile in the region of saddles  11 . 1 ,  12 . 1 ,  21 . 1 ,  22 . 1  in the direction of longitudinal axis L. 
     The three crimp insert pairs  10 ,  20 ,  30  are joined to form crimp indenters  100 ,  200 , in the shape of a sandwich as illustrated in  FIGS. 4   a  and  4   b , so that crimpers  11 ,  21 ,  31  and anvils  12 ,  22 ,  32  are disposed at a mutual offset in relation to longitudinal axis L. First crimping indenter  100  includes crimpers  11  and  31  and anvil  22 . In first crimping indenter  100 , anvil  22  is situated between the two crimpers  11 ,  31 . Second crimping indenter  200  is assigned anvils  12 ,  32  and crimper  21 . For crimping indenter  200 , crimper  21  is situated between the two anvils  12 ,  32 . 
     A cable, as illustrated in  FIGS. 5 to 8 , is to be produced with the aid of crimping indenters  100 ,  200  shown in  FIGS. 4   a  and  4   b . In the center, the cable has a filler  1  formed of an insulating material, about which four wires  2  enclosed by insulation  3  are disposed in twisted manner. A shield  4 , e.g., in the form of a shield mesh, is situated radially outside in relation to wires  2  provided with insulation  3 . Shield  4  is enclosed by an insulating jacket  6  (see  FIG. 5 ) over the majority of the cable length. Such cables are also frequently referred to as star quads. The four wires  2  including their insulations  3  are twisted together, which achieves high cross-talk damping. 
     In the course of the cable assembly, insulating jacket  6  is first removed in an end region of an electrical line, so that shield  4  is exposed in this end region. Next, an electrically conductive support clamp  5 , which has a slot  5 . 1  (see  FIG. 6 ), is press-fit around shield  4 , and shield  4  is folded over around support clamp  5 , e.g., inverted. Sleeve  7  is then slipped onto inverted shield  4 . Such a sleeve  7  may also be referred to as outer conductor sleeve. In the region where crimping is to be performed, the outer diameter of sleeve  7  is slightly larger than double the radius R, r of saddles  11 . 1 ,  12 . 1 ,  21 . 1 ,  22 . 1 . 
     A crimping process subsequently creates an electrical and mechanical connection between sleeve  7  and shield  4 . For this purpose sleeve  7  situated on the cable is placed between crimping indenters  100 ,  200 . Crimping indenter  100  illustrated in  FIG. 4   b  is then moved in the direction of second crimping indenter  200 , until the hollow-cylindrical part of sleeve  7  is press-fit against shield  4  to the desired extent. 
     In the region of sleeve  7 , the cable produced in this manner has three circumferential sections I, II, III, which are disposed at an axial offset relative to the direction of longitudinal axis L of sleeve  7 . The axial length of each section I, II, III results from thickness D, d of crimpers  11 ,  21 ,  31  or anvils  12 ,  22 ,  32  (see  FIGS. 7 and 8 ). In the exemplary embodiment illustrated, sections I and III have an axial length of 2 mm, while center section II has an axial length of 1 mm. Sections I, II, III may thus be considered virtual disks in geometrical terms, which have thicknesses D and d and end faces that have an orthogonal orientation to longitudinal axis L. 
     It is possible to geometrically subdivide sleeve  7  into two sleeve halves  7   a ,  7   b , a longitudinal section plane M, which is located in the center in relation to sleeve  7  in this case, geometrically separating the two sleeve halves  7   a ,  7   b . Sleeve halves  7   a ,  7   b  thus are arranged in the approximate shape of tubular half-shells. Considered in geometrical terms, longitudinal axis L therefore is located on longitudinal section plane M, so that longitudinal section plane M thus simultaneously constitutes the drawing plane of  FIG. 7  and  FIG. 8 . 
     In the assembled cable, sleeve  7  encloses shield  4 , so that shield  4  is resting against support clamp  5  both on the radially inner side of support clamp  5  and on the radially outer side of support clamp  5 . 
     Due to the slightly smaller radius r of saddles  22 . 1 ,  22 . 2  of second crimp insert pair  20 , a constriction is produced in second section II, e.g., crimped sleeve  7  has a smaller diameter in second section II. 
     The crimping produces crimp ridges  7 . 1  to  7 . 6  in sleeve  7  as a result of the crimping operation, so that, within first and third axial sections I, III in first sleeve half  7   a , sleeve  7  has two crimp ridges  7 . 1 ,  7 . 2 ;  7 . 5 ,  7 . 6  in first sleeve half  7   a . In second sleeve half  7   b , sleeve  7  is free of crimp ridges in first and third axial sections I, III, e.g., concave throughout on the inside, so that uniform press-fitting, largely without geometrical interruptions, of the shield takes place there. Furthermore, sleeve  7  is provided without crimp ridges within second section II in first sleeve half  7   a , while it has two crimp ridges  7 . 3 ,  7 . 4  in second sleeve half  7   b . In the exemplary embodiment shown, crimp ridges  7 . 1 ,  7 . 2  in first section I, crimp ridges  7 . 3 ,  7 . 4  in second section II, and crimp ridges  7 . 5 ,  7 . 6  in third section III are disposed about longitudinal axis L at a distance from each other, at a center angle β. In this case, the center angle β amounts to, e.g., 120°. A center angle denotes the central angle about a point on longitudinal axis L within the particular section I, II, III. It should be understood that the shortest distance is meant as relevant center angle and not, for example, the complementary angle (in this case, 240°) in relation to the 360° circumference. Sleeve half  7   a  has a convex shape throughout at its outer side in second section II. It has radius r there, while sleeve half  7   b  has a convex shape throughout at its outer side in first section I and third section III, these sections I, III having radius R. An excellent electrical connection is obtained between shield  4  and sleeve  7  due to the special arrangement of the crimping. In addition, increased mechanical tensile strength is provided as well. 
     The cable may be used in motor vehicles, for example, for the purpose of transmitting HF signals (high frequency signals). In particular, the cable may be used for establishing a so-called FAKRA (Fachkreis Automobil) mating connection. Adaptor  8  illustrated in  FIGS. 1 and 5  may be used to affix a secondary locking mechanism in the correct position. Due to the high data transmission rates such as 480 MBit/s, high voltage frequencies on the order of magnitude of 40 MHz, for example, arise in the cable. A conventional cable may cause relatively high radiation levels. The high radiation levels may trigger interference in the onboard electronics of a vehicle, in particular, which must be avoided under all circumstances, especially in the case of safety-relevant functions of the onboard electronics. The configuration of the cable described herein may achieve extremely satisfactory EMC impermeability, so that radiation levels of the cable in the region of the mating connector or sleeve  7  are sharply reduced.