Patent Publication Number: US-2018041020-A1

Title: Seal structure for multiple-core cable

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of Japanese patent application JP2015-048398 filed on Mar. 11, 2015, the entire contents of which are incorporated herein. 
     Technical Field 
     The technology disclosed in this specification relates to a seal structure for a multiple-core cable. 
     Background Art 
     A multiple-core cable has a structure in which a plurality of electrical wires are covered by a sheath that is made of an insulating resin material, and, conventionally, a seal structure (water stop structure) for the terminal portion of a multiple-core cable is disclosed in JP 2012-182924A (referred to as Patent Document 1 hereinafter). In this seal structure, terminal processing is performed on the multiple-core cable to branch off each electrical wire from the terminal of the sheath, a hot-melt block that includes partition walls for partitioning the electrical wires from each other is attached to the branched-off electrical wires, and then a heat-shrink tube is placed over the group of electrical wires so as to surround the terminal of the sheath. Thereafter, heat processing is performed to melt the hot-melt block and fill the gaps between the electrical wires so as to waterproof the spaces between the electrical wires, and then the heat-shrink tube is heated so as to shrink, thus preventing the intrusion of water from the group of electrical wires into the terminal of the sheath. 
     SUMMARY 
     With this conventional seal structure, the process of heating and melting the hot-melt resin and then allowing cooling and hardening in particular is time-consuming, and therefore it cannot necessarily be said that this seal structure is satisfactory when taking operation efficiency into account. 
     The technology disclosed in this specification was achieved in light of the above-described situation. 
     A seal structure for a multiple-core cable disclosed by this specification includes: a multiple-core cable in which a plurality of electrical wires are enveloped by a sheath, and the plurality of electrical wires extend out from a terminal of the sheath; a rubber plug provided with a sheath covering portion that is fitted around the terminal of the sheath, and an electrical wire through-hole portion that has a plurality of through-holes through which the electrical wires respectively pass; and a clamping member that is attached to the sheath covering portion and the electrical wire through-hole portion of the rubber plug and can clamp the sheath covering portion and the electrical wire through-hole portion from an outer circumferential side. 
     The sheath covering portion provided in the rubber plug is fitted around the terminal of the sheath of the multiple-core cable, and the electrical wires that extend out from the terminal of the sheath are inserted into the through-holes of the electrical wire through-hole portion provided in the same rubber plug, and thereafter the sheath covering portion and the electrical wire through-hole portion are clamped by the clamping member from the outer circumferential side. Accordingly, the inner peripheral surface of the sheath covering portion is in close contact with the outer peripheral surface of the terminal of the sheath with a predetermined contact pressure over the entire circumference, and the inner peripheral surfaces of the through-holes of the electrical wire through-hole portion are in close contact with the outer peripheral surfaces of the electrical wires with a predetermined contact pressure over the entire circumference, consequently sealing the terminal of the sheath as well as the regions surrounding the electrical wires. By employing an assembly format that uses the rubber plug and the clamping member, it is possible to construct the seal structure in a shorter time, thus making it is possible to reduce manufacturing cost, and by including the clamping member in particular, it is possible to ensure reliable seal functionality. 
     Configurations such as the following are also possible. 
     The clamping member has a sheath covering portion clamping member that is attached to the sheath covering portion, and an electrical wire through-hole portion clamping member that is attached to the electrical wire through-hole portion, and the sheath covering portion clamping member and the electrical wire through-hole portion clamping member are provided integrally. Accordingly, the number of components is reduced, and the clamping member attachment operation is also simplified. 
     The clamping member is provided on a bracket for attachment to a vehicle. The seal structure is constructed with use of the bracket that specifies the attachment position of the terminal portion of the multiple-core cable, thus making it possible to achieve a more neatly organized multiple-core cable routing structure. 
     The clamping member is formed by a C-shaped clamping ring that includes an insertion groove extending along the axial direction and that is capable of elastic deformation in a diameter direction. 
     The clamping ring can be fitted around the sheath covering portion and the electrical wire through-hole portion while inserting the sheath covering portion and the electrical wire through-hole portion into the clamping ring in the diameter direction through the insertion groove. The clamping member attachment operation is simplified. 
     According to the technology disclosed by this specification, an assembly format is achieved for the seal structure, thereby making it possible to construct the seal structure in a shorter time, and thus making it is possible to reduce manufacturing cost, while also making it possible to ensure reliable seal functionality. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of the structure of a seal portion according to an embodiment. 
         FIG. 2  is a front view of the structure of the seal portion. 
         FIG. 3  is a side view of the structure of the seal portion. 
         FIG. 4  is a cross-sectional view taken along line IV-IV in  FIG. 2 . 
         FIG. 5  is a cross-sectional view taken along line V-V in  FIG. 2 . 
         FIG. 6  is a cross-sectional view taken along line VI-VI in  FIG. 2 . 
         FIG. 7  is a cross-sectional view taken along line VII-VII in  FIG. 3 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiment 
     An embodiment will be described below with reference to  FIGS. 1 to 7 . In the present embodiment, a four-core cable is given as an example of a multiple-core cable  10 , and application as, for example, a wire harness for an electrical parking brake installed in a vehicle is possible. 
     As shown in  FIG. 1 , a seal structure is constructed by attaching a rubber plug  20  to a terminal portion of the multiple-core cable  10 , and attaching the rubber plug  20  to a bracket  30  for attachment to a predetermined position in a vehicle. 
     The multiple-core cable  10  is a four-core round cable as described above, and has a structure in which four electrical wires  11  (referred to as a group of electrical wires  14  when appropriate) are enveloped by a sheath  15  that is made of an insulating resin. The electrical wires  11  are each a sheathed electrical wire (see  FIG. 4 ) constituted by a metal core wire  12  that is covered by an insulating covering  13  made of a synthetic resin, and the electrical wires  11  include two each of two types of electrical wires  11 L and  11 S that have different outer diameters. The two first electrical wires  11 L that have a larger diameter function as connection wires for connection to a motor for an electrical parking brake, and the two second electrical wires  11 S that have a smaller diameter function as signal lines for sensors in an anti-lock brake system. 
     The terminal portion of the multiple-core cable  10  is subjected to predetermined terminal processing such as stripping so as to have a structure in which the four electrical wires  11 L and  11 S are lead out and branched off from a terminal  15 A (see  FIG. 6 ) of the sheath  15 , and the rubber plug  20  is attached to the terminal portion of the multiple-core cable  10  having this structure. 
     As shown in  FIGS. 2, 6, and 7 , the rubber plug  20  is shaped as a horizontally elongated circular column having an outer diameter dimension that is a predetermined amount larger than the multiple-core cable  10 . 
     A sheath covering portion  21 , which is shaped as a cylinder that is open at the rear face, is formed in a region having a predetermined length (approximately ⅔ of the total length) in the rear portion side (right side in  FIG. 6 ) of the rubber plug  20 , and this sheath covering portion  21  can be substantially tightly fitted around the terminal  15 A of the sheath  15 . 
     A solid electrical wire through-hole portion  23  is formed in the remaining front end portion of the rubber plug  20 . As shown in  FIGS. 5 to 7 , two first through-holes  25 L and two second through-holes  25 S, through which the larger-diameter first electrical wires  11 L and the smaller-diameter second electrical wires  11 S substantially tightly pass individually, are formed in the electrical wire through-hole portion  23 . 
     Regarding the formation locations of the first through-holes  25 L and the second through-holes  25 S, as shown in  FIG. 5 , the two first through-holes  25 L are formed vertically side-by-side with a predetermined gap therebetween in a region approximately on one side of the center line (vertical line) in the diameter direction of the electrical wire through-hole portion  23 , and the two second through-holes  25 S are formed vertically side-by-side with a predetermined gap therebetween on the other side. 
     Also, a bracket  30  is provided in order for the terminal portion of the multiple-core cable  10 , which is provided with the seal structure, to be attached to a predetermined location in a vehicle. This bracket  30  is formed with the shape shown in  FIGS. 1 to 3  by performing press processing on a metal plate that has elasticity, such as a spring steel plate. 
     The bracket  30  includes an attachment base plate  31  in which an attachment hole  32  (bolt insertion hole) is formed, and two clamping rings  35  (one example of a clamping member) are formed so as to protrude in a forked manner from a peripheral edge on the leading end side (upper end) of the attachment base plate  31 . 
     The clamping rings  35  include a sheath covering portion clamping ring  35 A that is attached to the sheath covering portion  21 , and an electrical wire through-hole portion clamping ring  35 B that is attached to the electrical wire through-hole portion  23 . The clamping rings  35  are constituted by belt-like pieces  34  that extend parallel to each other from the upper end of the attachment base plate  31 , and the leading ends of the belt-like pieces  34  are bent over toward the base end side so as to form a C-shaped cross-section that has a diameter dimension somewhat smaller than the outer diameter of the rubber plug  20 . An insertion groove  36  that extends in the axial direction is formed between the base end and the bent-over leading ends of the belt-like pieces  34  so as to allow insertion of the rubber plug  20  (sheath covering portion  21  and electrical wire through-hole portion  23 ) in the diameter direction. A guide portion  37  that extends in a diagonally outward direction is formed at the leading end of each of the clamping rings  35  (belt-like pieces  34 ). 
     In other words, the bracket  30  is shaped such that the two clamping rings  35  having the same above-described shape protrude in a forked manner from a peripheral edge (upper edge) of the attachment base plate  31  with a predetermined gap therebetween on the same axis. Note that a rotation stop piece  39 , which is L-shaped and is for preventing rotation, is formed on a peripheral edge (lower edge) on the side of the attachment base plate  31  that is opposite to the side where the clamping rings  35  are provided. 
     Next, an example of an assembly procedure according to the present embodiment will be described. 
     First, terminal processing is performed on the multiple-core cable  10 , that is to say a predetermined length of the sheath  15  is stripped such that the four electrical wires  11 L and  11 S are lead out from the terminal  15 A of the remaining sheath  15  in an appropriately separated state. 
     In this state, the terminals of the first electrical wires  11 L and the second electrical wires  11 S are placed inside the sheath covering portion  21  of the rubber plug  20  from the rear, then inserted into the corresponding first through-holes  25 L and second through-holes  25 S formed in the electrical wire through-hole portion  23 , and pushed forward from the front surface of the electrical wire through-hole portion  23 . Subsequently, the terminal  15 A of the sheath  15  is inserted into the sheath covering portion  21  while pulling the protruding electrical wires  11 L and  11 S forward. As shown in  FIGS. 6 and 7 , when the terminal  15 A of the sheath  15  reaches the vicinity of the deep-side surface of the sheath covering portion  21 , the pulling of the electrical wires  11 L and  11 S and the pushing of the terminal  15 A of the sheath  15  is stopped. This thus obtains a state in which the rubber plug  20  is attached to the terminal portion of the multiple-core cable  10 . 
     Subsequently, the rubber plug  20 , which is attached to the terminal portion of the multiple-core cable  10  as described above, is attached to the bracket  30 . Specifically, the rubber plug  20  is brought into contact with the attachment base plate  31  of the bracket  30  and then pressed toward the two front and rear clamping rings  35 . When the portion of the rubber plug  20  located toward the rear end side of the sheath covering portion  21 , and the electrical wire through-hole portion  23  come into contact with the guide portions  37  of the corresponding clamping rings  35 , and are then further pressed, they cause the clamping rings  35  to elastically increase in diameter so as to open the insertion groove  36 , and are pushed inside. 
     When these portions are pushed farther and pass through the insertion groove  36 , as shown in  FIGS. 4 and 5 , the clamping rings  35  decrease in diameter due to elastic restoration force, and the portion of the sheath covering portion  21  toward the rear end and the electrical wire through-hole portion  23  are clamped by the corresponding clamping rings  35  from the outer circumferential side over substantially the entire circumference. Accordingly, the inner peripheral surface of the sheath covering portion  21  is in close contact with the outer peripheral surface of the terminal  15 A of the sheath  15  with a predetermined contact pressure over the entire circumference, and the inner peripheral surfaces of the through-holes  25 L and  25 S of the electrical wire through-hole portion  23  are in close contact with the outer peripheral surfaces of the electrical wires  11 L and  11 S with a predetermined contact pressure over the entire circumference, consequently sealing the terminal  15 A of the sheath  15  as well as the regions surrounding the electrical wires  11 L and  11 S. 
     The bracket  30  with the rubber plug  20  attached thereto in this way is arranged at a set attachment location in the vehicle and fixed by screwing a bolt (not shown) through the attachment hole  32 . Accordingly, the terminal portion of the multiple-core cable  10  with the constructed seal structure is attached at a predetermined attachment location set in the vehicle. 
     Actions and effects such as the following can be obtained with the present embodiment. The sheath covering portion  21  of the rubber plug  20  is fitted around the terminal  15 A of the sheath  15  of the multiple-core cable  10 , the electrical wires  11 L and  11 S extending from the terminal  15 A of the sheath  15  are inserted through the through-holes  25 L and  25 S of the electrical wire through-hole portion  23  of the rubber plug  20 , and thereafter the sheath covering portion  21  and the electrical wire through-hole portion  23  are clamped from the outer circumferential side by the clamping rings  35  provided on the bracket  30 . Accordingly, the inner peripheral surface of the sheath covering portion  21  is in close contact with the outer peripheral surface of the terminal  15 A of the sheath  15  with a predetermined contact pressure over the entire circumference, and the inner peripheral surfaces of the through-holes  25 L and  25 S of the electrical wire through-hole portion  23  are in close contact with the outer peripheral surfaces of the electrical wires  11 L and  11 S with a predetermined contact pressure over the entire circumference, consequently sealing the terminal  15 A of the sheath  15  as well as the regions surrounding the electrical wires  11 L and Ss. 
     By employing this assembly format that uses the rubber plug  20  and the clamping rings  35 , the seal structure can be constructed in a shorter time than in the conventional case of using hot-melt resin, for example, thus making it possible to reduce manufacturing cost. In particular, the sheath covering portion  21  and the electrical wire through-hole portion  23  of the rubber plug  20  are clamped by the clamping rings  35  in a later step, thus making only low insertion force necessary for inserting the terminal  15 A of the sheath  15  into the sheath covering portion  21  and inserting the electrical wires  11  into the through-holes  25 L and  25 S of the electrical wire through-hole portion  23 , and ultimately making it possible to achieve close contact with high contact pressure, and to achieve improved seal functionality. 
     The sheath covering portion clamping ring  35 A and the electrical wire through-hole portion clamping ring  35 B are integrated with the bracket  30  for attachment to the vehicle, thereby reducing the number of components and also simplifying the operation of fitting the clamping rings  35 A and  35 B to the rubber plug  20  (sheath covering portion  21  and electrical wire through-hole portion  23 ). 
     In particular, this seal structure is constructed with use of the bracket  30  that specifies the attachment position of the terminal portion of the multiple-core cable  10 , thus making it possible to achieve a more neatly organized multiple-core cable  10  routing structure. 
     The clamping rings  35  are formed with a C-shaped cross-section that includes the insertion groove  36  extending in the axial direction and is capable of elastic deformation in the diameter direction. For this reason, the clamping rings  35  can be fitted around the sheath covering portion  21  and the electrical wire through-hole portion  23  while the sheath covering portion  21  and the electrical wire through-hole portion  23  are inserted into the clamping rings  35  in the diameter direction through the insertion groove  36 . In other words, the operation of fitting the clamping rings  35  can be performed easily. 
     Other Embodiments 
     The technology disclosed in the present specification is not intended to be limited to the embodiment described using the above descriptions and drawings, and aspects such as the following are also encompassed in the technical scope. 
     The assembly procedure illustrated in the above embodiment is merely one example, and other procedures may be included, such as first attaching the bracket to the vehicle, then attaching the rubber plug to the terminal portion of the multiple-core cable, and then attaching the rubber plug to the clamping rings. 
     The sheath covering portion clamping member and the electrical wire through-hole portion clamping member may be provided as members that are separate from each other. 
     As one example in which the sheath covering portion clamping member and the electrical wire through-hole portion clamping member are provided integrally, a structure is possible in which a sheath covering portion clamping ring and an electrical wire through-hole portion clamping ring are formed on two end portions of a long and narrow tubular body that has a C-shaped cross-section. 
     The clamping members may be provided as members that are separate from the bracket. 
     The clamping members may have another structure, such as a structure in which a bolt is provided, and the clamping members are reduced in diameter by tightening the bolt. 
     The number of electrical wires arranged in the multiple-core cable is not limited to the four wires illustrated in the above embodiments, and any number of wires greater than or equal to two may be included. 
     Although the case of providing two types of electrical wires that have different outer diameters is illustrated in the above embodiment, three or more types of electrical wires may be provided, or only one type of electrical wire may be provided. 
     Examples of the sheathed electrical wires that constitute the electrical wires include an electrical wire in which the core wire is a stranded wire in which a plurality of metal strands are twisted together, and a so-called single core wire constituted by a metal bar member. Also, the electrical wires may be shielded electrical wires. 
     The multiple-core cable may be a cable in which the sheath is filled with a filling material. 
     The multiple-core cable may be a so-called cab tire cable, or may be a multiple-core shielded wire in which a plurality of electrical wires are enveloped by a shielding layer. 
     It is to be understood that the foregoing is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims. 
     As used in this specification and claims, the terms “for example,” “e.g.,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation. 
     List of Reference Numerals 
       10  Multiple-core cable 
       11  Electrical wire 
       11 L First electrical wire 
       11 S Second electrical wire 
       15  Sheath 
       15 A Terminal (of sheath  15 ) 
       20  Rubber plug 
       21  Sheath covering portion 
       23  Electrical wire through-hole portion 
       25 L First through-hole 
       25 S Second through-hole 
       30  Bracket 
       35  Clamping ring (clamping member) 
       36  Insertion groove