Patent Publication Number: US-2021167587-A1

Title: Hot melt block, cable manufacturing method, and cable

Description:
TECHNICAL FIELD 
     This specification discloses a technique for keeping water from entering the inside of a cable. 
     BACKGROUND 
     Conventionally, the technique for keeping water from entering the inside of a cable has been known. In Patent Document 1, a hot melt block with a cross-shaped cross-section is assembled between electric wires drawn out from a multi-core cable in which a plurality of electric wires are collectively surrounded by a sheath, and the hot melt block is provided with partition walls for partitioning the electric wires. Further, the multi-core cable includes a heat-shrinkable tube that covers outer circumferences of the electric wires to which the hot melt block is assembled and the outer circumference of the sheath. As a result of heat-treating the multi-core cable to melt the hot melt block and fill it between the wires, water is prevented from entering between the wires, and as a result of heat-shrinking the heat-shrinkable tube, water is prevented from entering between the outer circumferences of the electric wires and the outer circumference of the sheath. 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         Patent Document 1: JP 2012-182924A 
       
    
     SUMMARY OF THE INVENTION 
     Problems to be Solved 
     In the configuration disclosed in Patent Document 1, the position of the hot melt block assembled between the electric wires is held as a result of the partition walls being disposed between the electric wires, however, there is concern that, if the hot melt block is displaced during heat treatment, a gap in which a melted hot melt is not filled will be created between the electric wires and that waterproof performance of the cable will be reduced. 
     The technique described in this specification has been completed based on the above circumstances, and an object thereof is to suppress a reduction in waterproof performance due to displacement of the hot melt block. 
     Means to Solve the Problem 
     A hot melt block described in this specification is a hot melt block that is assembled at a portion where an insulating sheath of a cable in which a plurality of electric wires are collectively surrounded by the insulating sheath is removed and the electric wires are drawn out, and that is melted through heating. The hot melt block includes: an insertion portion that can be inserted between the electric wires surrounded by the sheath; and a spacer that is fixed to the insertion portion, and is disposed between the electric wires at the portion where the electric wires are drawn out. 
     A cable manufacturing method described in this specification is a cable manufacturing method in which a hot melt block is assembled at a portion where an insulating sheath of a cable in which a plurality of electric wires are collectively surrounded by the insulating sheath is removed and the electric wires are drawn out, and, in a state where a heat-shrinkable tube surrounds the electric wires to which the hot melt block is assembled, the hot melt block and the heat-shrinkable tube are heated to melt the hot melt block and shrink the heat-shrinkable tube to be brought into close contact with the electric wires. The hot melt block includes: an insertion portion that can be inserted between the electric wires surrounded by the sheath; and a spacer to which the insertion portion is fixed, and that is disposed between the electric wires in a state where the sheath is removed and the electric wires are drawn out. The cable manufacturing method includes: an assembling step of assembling the hot melt block to the cable so that the insertion portion is inserted between the cables surrounded by the sheath and the spacer is disposed between the electric wires in the state where the sheath is removed and the electric wires are drawn out; and a heating step of heating the hot melt block and the heat shrink tube in a state where the cable to which the hot melt block is assembled in the assembly step is inserted into the heat-shrinkable tube. 
     A cable described in this specification is a cable including: a plurality of electric wires; an insulating sheath that collectively surrounds the electric wires; a heat-shrinkable tube that covers an end portion of the sheath and the electric wires in a state where the sheath is removed and the electric wires are drawn out, in a close contact state; and a hot melt that is disposed between the electric wires to prevent water from the entering. The hot melt is in close contact with the electric wires surrounded by the sheath, and is filled between the electric wires in the state where the sheath is removed and the electric wires are drawn out. 
     According to the above configuration, by inserting the insertion portion of the hot melt block between the electric wires surrounded by the sheath, it is possible to suppress displacement of the hot melt block during heating. Thus, it is possible to suppress a reduction in waterproof performance due to displacement of the hot melt block. In addition, if the insertion portion is melted through heating, it is possible to fill the gap between the electric wires surrounded by the sheath, thereby keeping water from entering between the electric wires. 
     The following aspects are preferable embodiments of the technique described in this specification. 
     The insertion portion is formed in a tapered shape. 
     In this way, the insertion portion can be easily inserted when assembling the hot melt block. 
     The insertion portion is provided with an insertion wall that partitions the electric wires adjacent to each other. 
     In this way, positioning accuracy of the insertion portion can be improved by the insertion wall that separates the adjacent electric wires. 
     The spacer includes a main body disposed between the electric wires, and an overhang that projects radially from a rear end portion of the main body and partitions the electric wires. 
     In this way, the distance between the adjacent electric wires can be maintained by the overhang. 
     The electric wires include a signal line and a power line with an outer diameter larger than that of the signal line. 
     In this way, because the outer diameters of the electric wires are different, displacement of the hot melt block can be suppressed by the insertion portion inserted between the electric wires in a configuration in which the hot melt block is likely to be displaced between the electric wires. 
     Effect of the Invention 
     According to the technique described in this specification, it is possible to suppress a reduction in waterproof performance due to displacement of the hot melt block. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a waterproof portion of a cable of Embodiment 1. 
         FIG. 2  is a cross-sectional view illustrating the waterproof portion of the cable. 
         FIG. 3  is an exploded perspective view of the cable. 
         FIG. 4  is a perspective view illustrating a state in which a hot melt block is assembled to a cable and inserted into a heat-shrinkable tube. 
         FIG. 5  is a cross-sectional view of the state of  FIG. 4 . 
         FIG. 6  is a perspective view illustrating a hot melt block of Embodiment 2. 
         FIG. 7  is a perspective view illustrating a hot melt block of Embodiment 3. 
         FIG. 8  is a perspective view illustrating a hot melt block of Embodiment 4. 
         FIG. 9  is a perspective view illustrating a hot melt block of Embodiment 5. 
     
    
    
     DETAILED DESCRIPTION TO EXECUTE THE INVENTION 
     Embodiment 1 
     A cable  10  ( FIG. 1 ) of the present embodiment can be, for example, routed between a power source such as a battery and a load such as an in-vehicle electrical component or a motor, in a vehicle such as an automobile. The cable  10  can be disposed extending in any direction, but in the following, the left side of  FIG. 2  will be described as the front side and the right side will be described as the rear side. 
     As illustrated in  FIGS. 2 and 3 , the cable  10  includes a cable body  10 A in which a sheath  16  is removed and a plurality of electric wires  11  and  12  are drawn out to the rear side, a hot melt  18  that prevents water from entering at a portion where the electric wires  11  and  12  are drawn out, and a heat-shrinkable tube  19  that covers a region between an end portion of the sheath  16  and the electric wires  11  and  12  drawn out to the rear side, in a close contact state. 
     The cable body  10 A includes the electric wires  11  and  12 , the sheath  16  that collectively surrounds the electric wires  11  and  12 , and a filling member  17  disposed in a gap between the electric wires  11  and  12  and the sheath  16 . In the present embodiment, the electric wires  11  and  12  are four electric wires each with a circular outer circumference, and include two power lines  11  through which a driving current of the motor or the like flows and two signal lines  12  through which a smaller current than that of the power line  11  flows, the outer diameter of the signal line  12  being smaller than that of the power line  11 . Each of the electric wires  11  and  12  includes a core wire  13  and an insulating coating  14  made of an insulating synthetic resin that covers the outer circumference of the core wire  13 . The core wire  13  is made of, for example, a metal such as aluminum, an aluminum alloy, copper, or a copper alloy, and a stranded wire made by twisting together fine metal wires, a single core wire made of a single metal, or the like can be used. Note that, at an end portion of each of the electric wires  11  and  12 , a terminal (not shown) to be connected to a mating terminal (not shown) is attached through crimping or the like to the core wire  13  exposed by removing the insulating coating  14 . 
     The sheath  16  is made of an insulating synthetic resin, has a cylindrical shape that collectively surrounds the electric wires  11  and  12 , and has an end  16 A formed by removing a rear end portion of the sheath  16 , and the electric wires  11  and  12  inside the sheath  16  are drawn out to the rear side of the end  16 A. The filling member  17  is formed by packing, for example, an insulating thread or paper tape between the electric wires  11  and  12  and the sheath  16 , and fills the gap between the electric wires  11  and  12  and the sheath  16  to hold the positions of the electric wires  11  and  12 , and suppresses deformation such as bending of the electric wires  11  and  12 . The electric wires  11  and  12  surrounded by the sheath  16  extend rearward from a rear end surface of the filling member  17 . 
     As illustrated in  FIG. 2 , the hot melt  18  has an embedded portion  18 A embedded between the electric wires  11  and  12  in the sheath  16 , and a filling portion  18 B filled inside the heat-shrinkable tube  19  in a region in which the electric wires  11  and  12  are drawn out. Note that the hot melt  18  on the rear side of the filling portion  18 B is a bulging portion  18 C protruding from the sheath  16 . The hot melt  18  is made of a solid thermoplastic adhesive (for example, PA (polyamide), EVA (ethylene vinyl alcohol), polyester-based adhesive, olefin or the like) at a predetermined temperature (for example, 25° C.), and a solid hot melt block  20  is softened or melted through heating to develop adhesiveness, and then solidified to form the hot melt  18 . 
     As illustrated in  FIG. 3 , the hot melt block  20  includes an insertion portion  21  that can be inserted from the rear side (outside) between the electric wires  11  and  12  surrounded by the end  16 A of the sheath  16 , and a cross-shaped spacer  24  that is integrally formed with the insertion portion  21  and is disposed between the electric wires  11  and  12  rearward of the end  16 A of the sheath  16 . 
     The insertion portion  21  has a conical tapered portion  21 A having an outer diameter that decreases in size toward its leading end, and a columnar pillar portion  22  connected to the rear side of the tapered portion  21 A. When the insertion portion  21  is inserted between the electric wires  11  and  12  surrounded by the sheath  16  and then solidified, it becomes the embedded portion  18 A that is in close contact with the electric wires  11  and  12  in the sheath  16  (see  FIG. 2 ). As illustrated in  FIG. 3 , the spacer  24  includes a core portion  24 A connected to the rear side of the insertion portion  21  and partition walls  25  that extend from the core portion  24 A in a cross shape in four directions and partition the electric wires  11  and  12 . Each partition wall  25  has a rectangular plate shape, and the electric wires  11  and  12  are arranged in an aligned state in a space between adjacent partition walls  25 . 
     The hot melt block  20  can be integrally formed through molding in which a molten resin is injected into a mold. The molding of the hot melt block  20  is not limited to this, and the insertion portion  21  and the spacer  24  may be formed separately, and the insertion portion  21  may be fixed to a front end portion of the spacer  24  by adhesion or the like. 
     The heat-shrinkable tube  19  is a tubular member that shrinks when heated, and has a size that surrounds the end portion of the sheath  16  and the electric wires  11  and  12  drawn out from the end portion of the sheath  16  before heating. Once heated, the heat-shrinkable tube  19  shrinks and its front end side (one end side) comes into close contact with the outer peripheral surface of the sheath  16  and its rear end side (other end side) comes into close contact with the outer peripheral surfaces of the electric wires  11  and  12  drawn out to the outside. The heat-shrinkable tube  19  can be formed of, for example, a two-layer synthetic resin material, in which an outer layer  19 B can be, for example, a polyolefin resin and a variant thereof, and an inner layer  19 A can be an adhesive made of, for example, EVA (ethylene vinyl alcohol), PA (polyamide), a polyester-based adhesive, or the like. The adhesive can be a thermoplastic adhesive that develops adhesiveness due to softening or melting as a result of being heated. Note that as illustrated in  FIG. 2 , a front side of the inner layer  19  is a protruding portion  19 AA protruding on the forward side of the outer layer  19 B. 
     Next, a manufacturing process of the cable  10  according to the present embodiment will be described. 
     The end portion of the sheath  16  of the cable  10  in which the electric wires  11  and  12  are collectively surrounded by the sheath  16  is stripped off so that the electric wires  11  and  12  are drawn out to the outside in an exposed state ( FIG. 3 ). 
     (Assembly Step) 
     Next, as illustrated in  FIGS. 4 and 5 , the hot melt block  20  is assembled between the electric wires  11  and  12  in a state of being drawn out to the rear side of the sheath  16 , and the sheath  16  and the electric wires  11  and  12  that are drawn out are passed through the tubular heat-shrinkable tube  19  before being shrunk, to a predetermined position. In the assembly of the hot melt block  20 , the insertion portion  21  of the hot melt block  20  is inserted between the electric wires  11  and  12  surrounded by the end  16 A of the sheath  16 , and each of the electric wires  11  and  12  is inserted into a space between the adjacent partition walls  25  of the hot melt block  20 . 
     (Heating Step) 
     Then, the cable  10  is inserted into a heating apparatus (not shown) to undergo heat treatment. As a result of performing heat treatment, the melted hot melt block  20  permeates to be filled between the electric wires  11  and  12  and then solidifies, thus preventing water from entering between the electric wires  11  and  12 , and the heat-shrinkable tube  19  is heat-shrunk, thus preventing water from entering from the outer peripheral side of the sheath  16  and the outer peripheral side of the electric wires  11  and  12 . 
     According to the above embodiment, the following operations and effects are obtained. 
     Provided is the hot melt block  20  that is assembled at a portion where an insulating sheath  16  of the cable  10  in which the electric wires  11  and  12  are collectively surrounded by the insulating sheath  16  is removed and the electric wires  11  and  12  are drawn out, and that is melted through heating. The hot melt block  20  includes: an insertion portion  21  that can be inserted between the electric wires  11  and  12  surrounded by the sheath  16 ; and a spacer  24  that is fixed to the insertion portion  21 , and is disposed between the electric wires  11  and  12  at the portion where the sheath is removed and the electric wires are drawn out. 
     According to the present embodiment, because the position of the hot melt block  20  is held by inserting the insertion portion  21  of the hot melt block  20  between the electric wires  11  and  12  surrounded by the sheath  16 , displacement of the hot melt block during heating can be suppressed. Thus, a gap is less likely to occur between the electric wires  11  and  12  due to displacement of the hot melt block  20  and a reduction in waterproof performance can be suppressed. Further, when the insertion portion  21  is melted through heating, the gap between the electric wires  11  and  12  surrounded by the sheath  16  can be filled, thereby keeping water from entering between the electric wires  11  and  12 . 
     Further, the insertion portion  21  is formed in a tapered shape. 
     In this way, the insertion portion  21  can be easily inserted when assembling the hot melt block  20 . 
     The electric wires  11  and  12  include the signal line  12  and the power line  11  that has an outer diameter larger than that of the signal line  12 . 
     In this way, since the outer diameters of the electric wires  11  and  12  are different, in a configuration in which the hot melt block  20  is likely to be displaced between the electric wires  11  and  12 , displacement of the hot melt block  20  can be suppressed by the insertion portion  21  inserted between the electric wires  11  and  12 . 
     Embodiment 2 
     Next, Embodiment 2 will be described with reference to  FIG. 6 . Embodiment 2 is different from Embodiment 1 in the shape of an insertion portion  31  of a hot melt block  30 . Since the other components are the same as those in Embodiment 1, the same components as those in Embodiment 1 are denoted by the same reference numerals and a description thereof will be omitted. 
     The hot melt block  30  includes an insertion portion  31  that can be inserted between the electric wires  11  and  12  surrounded by the end  16 A of the sheath  16 , and a spacer  24 . The insertion portion  31  includes a first insertion wall  32 A that partitions the electric wires  11  and  12  surrounded by the sheath  16 , and a second insertion wall  32 B that extends in a direction intersecting the first insertion wall  32 A. 
     The leading end of the first insertion wall  32 A and the leading end of the second insertion wall  32 B are connected via a recessed surface  34  extending along the outer peripheral surface of each of the electric wires  11 . A pair of recessed surfaces  35  extending along the outer peripheral surfaces of a pair of electric wires  12  are formed on a lower surface of the second insertion wall  32 B. The leading end of each of the first insertion wall  32 A, the second insertion wall  32 B, and the recessed surfaces  34  and  35  is a tapered portion  36  having a thickness dimension decreasing in an inclined manner toward the forward side. 
     According to the second embodiment, accuracy of positioning of the insertion portion  31  can be improved by the insertion walls  32 A and  32 B that partition the adjacent electric wires  11  and  12 . 
     Embodiment 3 
     Next, Embodiment 3 will be described with reference to  FIG. 7 . Embodiment 3 is different from Embodiment 1 in the shape of a spacer  41  of a hot melt block  40 . Since the other components are the same as those in Embodiment 1, the same components as those in Embodiment 1 are denoted by the same reference numerals and a description thereof will be omitted. 
     The hot melt block  40  includes the insertion portion  21  and the spacer  41  fixed to the insertion portion  21  and disposed between the electric wires  11  and  12  drawn out rearward at the end  16 A of the sheath  16 . The spacer  41  has a columnar shape, and its front end portion has an outer peripheral surface cut out in a tapered shape. The axial center of the spacer  41  is disposed at a central portion between the electric wires  11  and  12  drawn out rearward at the end  16 A. 
     Embodiment 4 
     Next, Embodiment 4 will be described with reference to  FIG. 8 . Embodiment 4 is different from Embodiment 3 in that an overhang  53  is provided at a rear end portion of a hot melt block  50 . Since the other components are the same as those in Embodiment 3, the same components as those in Embodiment 3 are denoted by the same reference numerals and a description thereof will be omitted. 
     A spacer  51  of the hot melt block  50  includes a columnar main body  52  disposed between the electric wires  11  and  12 , and the overhang  53  that projects radially with respect to an axial direction of the hot melt block  50  and partitions the electric wires  11  and  12 . The overhang  53  has a plate shape in which a partition portion  54  for partitioning the electric wires  11  and  12  extends in a cross shape in the radial direction, and is integrally formed with a rear end portion of the main body  52 . 
     According to Embodiment 4, the distance between the adjacent electric wires  11  and  12  can be maintained by the overhang  53 . Further, when assembling the hot melt block  50 , the overhang  53  can be used for positioning the hot melt block  50  in a front-rear direction (direction of insertion direction into the heat-shrinkable tube  19 ). 
     Embodiment 5 
     Next, Embodiment 5 will be described with reference to  FIG. 9 . Embodiment 5 is different from Embodiment 4 in the shape of an overhang  62  of a hot melt block  60 . Since the other components are the same as those in Embodiment 4, the same components as those in Embodiment 4 are denoted by the same reference numerals and a description thereof will be omitted. 
     A spacer  61  of the hot melt block  60  includes the main body  52  and the overhang  62  that projects radially with respect to the axial direction of the hot melt block  60  and partitions a pair of electric wires  11 . The overhang  62  has a rectangular plate shape and stands upward (radially) from the rear end portion of the main body  52 . 
     Other Embodiments 
     The technique described in the present specification is not limited to the embodiments described in the above description and drawings, and for example, the following embodiments are also included in the technical scope of the technique described in the present specification. 
     (1) The number of electric wires  11  and  12  is not limited to four, and can be changed as appropriate. Further, the cable is not limited to a cable including both the power line  11  and the signal line  12 , and may be a cable including only one of the power line  11  and the signal line  12 . 
     (2) Combinations of the insertion portions  21  and  31  and the spacers  24 ,  41 ,  51  and  61  are not limited to the combinations of the above-described embodiments, and can be appropriately changed. Further, the shapes of the insertion portions and the spacers can also be changed as appropriate. For example, the tapered portions  21 A and  36  may not be formed in the insertion portions  21  and  31 . 
     LIST OF REFERENCE NUMERALS 
     
         
         
           
               10  Cable 
               11  Power line (Electric wire) 
               12  Signal line (Electric wire) 
               13  Core wire 
               14  Insulating coating 
               16  Sheath 
               17  Filling member 
               18  Hot melt 
               19  Heat-shrinkable tube 
               20 ,  30 ,  40 ,  50  Hot melt block 
               21 ,  31  Insertion portion 
               21 A,  36  Tapered portion 
               22  Pillar portion 
               24 ,  41 ,  51 ,  61  Spacer 
               24 A Core portion 
               25  Partition wall 
               30  Hot melt block 
               32 A First insertion wall (Insertion wall) 
               32 B Second insertion wall (Insertion wall) 
               53 ,  62  Overhang 
               62  Overhang