Abstract:
A connection structure includes a shield shell enclosing a part of a plurality of wires, a braided shield collectively covering the plurality of wires, a belt-shaped clamping member sandwiching the braided shield between it and an outer surface of the shield shell so as to press the braided shield against the shield shell by a clamping force thereof, and an annular member disposed between the braided shield and the clamping member and having an elasticity to be deformed by the clamping force of the clamping member. The clamping member presses the braided shield against the shield shell through the annular member.

Description:
[0001]    The present application is based on Japanese patent application No.2012-116512 filed on May 22, 2012, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a connection structure between a shield shell and a braided shield and to a wire harness using the connection structure. 
         [0004]    2. Description of the Related Art 
         [0005]    A structure for fixing a braided shield to a shield shell is known that the braided shield is formed by braiding plural conductive wires and covers plural wires (see, e.g., JP-A-2005-339933). 
         [0006]    The structure for fixing a braided shield described in JP-A-2005-339933 is configured such that the braided shield with an enlarged inner diameter is fitted to an oval ring portion of the shield shell and is clamped by a band. The band has a racetrack shape corresponding to an outer surface of the ring portion and presses the braided shield toward the ring portion of the shield shell by diameter reduction caused by fastening a bolt and a nut which are provided at a longitudinal end of the belt. 
       SUMMARY OF THE INVENTION 
       [0007]    In securing the braided shield to the shield shell, it is desirable that a clamping force of the band be applied to the braided shield (conductive wires) in an area as large as possible in order to ensure electrical connection between the braided shield and the shield shell and to prevent the braided shield from slipping off. However, the fixing structure disclosed in JP-A-2005-339933 is configured such that the braided shield is pressed against the shield shell by contact with the band. Therefore, even if the clamping force of the band is increased, the clamping force is concentrated on a portion of the braided shield and it is poorly effective to apply the clamping force of the band to the braided shield in a large area. 
         [0008]    It is an object of the invention to provide a connection structure between a shield shell and a braided shield that allows a clamping force of a clamping member to act on the braided shield in a larger area than the case of pressing the braided shield against the shield shell by contact with the clamping member, as well as a wire harness using the connection structure.
   (1) According to one embodiment of the invention, a connection structure comprises:
       a shield shell enclosing a part of a plurality of wires;   a braided shield collectively covering the plurality of wires;   a belt-shaped clamping member sandwiching the braided shield between it and an outer surface of the shield shell so as to press the braided shield against the shield shell by a clamping force thereof; and   an annular member disposed between the braided shield and the clamping member and having an elasticity to be deformed by the clamping force of the clamping member,   wherein the clamping member presses the braided shield against the shield shell through the annular member.   
       
 
         [0015]    In the above embodiment (1) of the invention, the following modifications and changes can be made.
       (i) The annular member comprises a tape wound several times so as to surround the braided shield.   (ii) A region of the shield shell facing an inside of the annular member comprises a convex arc shape at an entire circumference thereof and an outer surface thereof in a cross section orthogonal to an extending direction of the wires.   (iii) The annular member comprises a tape with an adhesive layer formed on one surface thereof.       (2) According to another embodiment of the invention, a wire harness comprises:
       a plurality of wires;   a shield shell enclosing a part of the plurality of wires;   a braided shield collectively covering the plurality of wires and contacting an outer surface of the shield shell;   a belt-shaped clamping member sandwiching the braided shield between it and the an outer surface of the shield shell so as to press the braided shield against the shield shell by a clamping force thereof; and   an annular member disposed between the braided shield and the clamping member and having an elasticity to be deformed by the clamping force of the clamping member.   
       
 
         [0025]    Points of the Invention 
         [0026]    According to one embodiment of the invention, a connection structure is constructed such that a braided shield, an annular member and a clamping member are sequentially provided on the outer surface of an accommodating portion of a shield shell. Thus, due to the elasticity of the annular member, the clamping force of the clamping member can be applied even to such a region that the clamping force of the clamping member would not be applied in the absence of the annular member. Thereby, the braided shield can be pressed against the outer surface of the accommodating portion of the shield shell. Therefore, a force of pressing the braided shield against the shield shell can be equalized by the annular member so as to increase an area of the braided shield to which the clamping force of the clamping member is applied. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    Next, the present invention will be explained in more detail in conjunction with appended drawings, wherein: 
           [0028]      FIG. 1  is a structural view showing a connection structure between a shield shell and a braided shield in an embodiment of the present invention and an example of a wire harness provided with such a connection structure; 
           [0029]      FIG. 2  is an exploded view of the wire harness shown in  FIG. 1 ; 
           [0030]      FIGS. 3A and 3B  are explanatory cross sectional views showing structures of a seal retainer, a housing and a shield shell; 
           [0031]      FIG. 4A  is a cross sectional view taken on line A-A of  FIG. 1  and  FIG. 4B  is an enlarged view showing a major portion in  FIG. 4A ; and 
           [0032]      FIG. 5  is a further enlarged view of the cross section of an annular member  5  in  FIGS. 4A and 4B . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiment 
       [0033]      FIG. 1  is a structural view showing a connection structure between a shield shell and a braided shield in the embodiment of the invention and an example of a wire harness provided with such a connection structure.  FIG. 2  is an exploded view of the wire harness shown in  FIG. 1 . 
         [0034]      FIGS. 3A and 3B  are explanatory cross sectional views showing structures of a seal retainer  2 , a housing  3  and a shield shell  4 , wherein  FIG. 3A  is a cross sectional view showing the seal retainer  2 , the housing  3  and the shield shell  4  taken along a second wire  12  and  FIG. 3B  is a cross sectional view showing a first member  31  constituting the housing  3 , together with the seal retainer  2 , the shield shell  4  and first to third wires  11  to  13 .  FIG. 4A  is a cross sectional view taken on line A-A of  FIG. 1  and  FIG. 4B  is an enlarged view showing a major portion in  FIG. 4A .  FIG. 5  is a further enlarged view of the cross section of an annular member  5  in  FIGS. 4A and 4B . 
         [0035]    A wire harness  1  is provided with the first to third wires  11  to  13 , a braided shield  10  covering the first to third wires  11  to  13 , the seal retainer  2  for inserting the first to third wires  11  to  13  and also for holding a sealing member  21  on an outer peripheral surface thereof, the housing  3  for holding the first to third wires  11  to  13 , the shield shell  4  for accommodating a portion of the housing  3 , the annular member  5  arranged so as to sandwich the braided shield  10  between itself and the shield shell  4  and a clamping member  6  arranged on an outer periphery of the annular member  5 . The wire harness  1  is used for connecting, e.g., an inverter to a motor as a driving force for moving a vehicle. 
         [0036]    The first to third wires  11  to  13  are wires for supplying, e.g., three-phase AC to a motor and have connecting terminals  110 ,  120  and  130  crimped and fixed at respective end portions on one side. In addition, the first to third wires  11  to  13  are respectively composed of cores  112 ,  122  and  132  and coverings  111 ,  121  and  131  formed of an insulating resin and covering the cores  112 ,  122  and  132 , as shown in  FIG. 4A . 
         [0037]    The braided shield  10  is formed by braiding, e.g., conductive wires formed of metal such as copper alloy and covers the first to third wires  11  to  13  all together. At an end portion of the braided shield  10  to be connected to the shield shell  4 , the inner diameter is enlarged by stretching mesh of the braid in a circumferential direction. 
         [0038]    The shield shell  4  is formed of a conductive metal and integrally has a cylindrical accommodating portion  41  for accommodating a portion of the housing  3  and a flange  42  used for attaching the shield shell  4  to an attachment target device (a motor or an inverter, etc.). In the present embodiment, the shield shell  4  is formed of a tin-plated steel sheet. Two attachment through-holes  420  are formed on the flange  42 , as shown in  FIG. 4A . 
         [0039]    The clamping member  6  is formed of a belt-shaped metal (e.g., stainless steel or iron) which is a different material from the shield shell  4 , and is arranged so as to sandwich the braided shield  10  between itself and the outer surface  41   a  of the accommodating portion  41  of the shield shell  4 . At one end of the clamping member  6 , plural (two) openings  61  are formed. And at another end, protrusions  62  are formed as many as the number of the openings  61 . 
         [0040]    The clamping member  6  is wound around the annular member  5  so that the end portion having the openings  61  covers an outer periphery of the other end portion having the protrusions  62 , and the clamping member  6  is clamped by a tool in a state that the protrusions  62  are fitted to the openings  61  so as to protrude therefrom, thereby generating a clamping force. A clamped portion  60  formed by the clamping is shaped into an Ω-shape which protrudes outward and curves in lateral view, as shown in  FIGS. 4A and 4B . 
         [0041]    The clamping member  6  presses the braided shield  10  against the accommodating portion  41  of the shield shell  4  by the clamping force thereof. Accordingly, the braided shield  10  comes into contact with the outer surface  41   a  of the shield shell  4  and is electrically connected to the shield shell  4 . 
         [0042]    The annular member  5  has elasticity to be deformed by the clamping force of the clamping member  6 . An inner peripheral surface of the annular member  5  is in contact with the braided shield  10  and an outer peripheral surface is in contact with the clamping member  6 . In the present embodiment, the annular member  5  is formed of a tape which is wound several times so as to surround the braided shield  10 . The tape is, e.g., an acetate cloth tape. The thickness of the tape is, e.g., 0.2 mm, and accordingly, the annular member  5  in case of winding the tape  5  times has a thickness of 1 mm. 
         [0043]    The annular member  5  is composed of a belt-shaped body  50  and an adhesive layer  51  which is tacky and is formed on a back surface  50   a  of the belt-shaped body  50 . Note that, the thickness of the adhesive layer  51  is exaggeratingly shown in  FIG. 5  for the purpose of explanation. 
         [0044]    The annular member  5  is wound around the braided shield  10  so that the back surface  50   a  faces toward the braided shield  10 . Accordingly, plural conductive wires  101  constituting the braided shield  10  sticks to the belt-shaped body  50  by the adhesive layer  51 . In addition, the adhesive layer  51  is in contact with the outer surface  41   a  of the accommodating portion  41  of the shield shell  4  through the mesh formed between the plural conductive wires  101  and the belt-shaped body  50  thus sticks to also the shield shell  4 . 
         [0045]    The clamping member  6  presses the braided shield  10  against the shield shell  4  (the outer surface  41   a  of the accommodating portion  41 ) via the annular member  5 . The annular member  5  has higher elasticity than the clamping member  6 . In addition, the belt-shaped body  50  of the annular member  5  has a wider width than the clamping member  6 . 
         [0046]    The seal retainer  2  has three insertion holes  20  for respectively inserting the first to third wires  11  to  13 , as shown in  FIG. 3B . A sealing member  22  for sealing between an outer peripheral surface of the first, second or third wire  11 ,  12  or  13  and an inner peripheral surface of the insertion hole  20  is held on an inner surface of the insertion hole  20 . 
         [0047]    As shown in  FIGS. 3A and 4A , the housing  3  is formed by coupling a first member  31  and a second member  32  which are formed of resin. The first member  31  has holding grooves  310  formed so as to respectively correspond to the first to third wires  11  to  13  and the second member  32  has holding grooves  320  formed so as to respectively correspond to the first to third wires  11  to  13  in the same manner. The holding grooves  310  and  320  have a semi-circular shape such that holding grooves  310  and holding grooves  320  form holding holes  30  (see  FIG. 3A ) for respectively holding the first to third wires  11  to  13  when the first member  31  is coupled to the second member  32 . 
         [0048]    As shown in  FIG. 4A , two engaging pieces  314  of the first member  31  are engaged with two engaging protrusions  325  of the second member  32  and two engaging pieces  324  of the second member  32  are engaged with two engaging protrusions  315  of the first member  31 , thereby coupling the first member  31  to the second member  32 . 
         [0049]    In region of the shield shell  4  (the accommodating portion  41 ) located inside the annular member  5 , the outer surface  41   a  has a convex arc shape throughout the entire circumference in a cross section orthogonal to an extending direction of the first to third wires  11  to  13 . The shape of the outer surface  41   a  is an oval shape having a major axis in an array direction of the first to third wires  11  to  13  (a vertical direction in  FIG. 4A ). In addition, a width in a minor axis direction orthogonal to the array direction (a horizontal width direction in  FIG. 4A ) is longest at the center of the major axis corresponding to a position of the second wire  12  and is gradually narrowed toward both end portions in the array direction. The outer surface  41   a  of the accommodating portion  41  is formed in a semi-circular shape at both end portions in the array direction of the first to third wires  11  to  13 . 
         [0050]    As shown in  FIG. 4A , the braided shield  10 , the annular member  5  and the clamping member  6  are arranged in this order on the outer side of the outer surface  41   a  of the accommodating portion  41 . The annular member  5  shrinks by tightening the clamping member  6  so that the diameter thereof is reduced. The shrinkage is large at a portion receiving a large clamping force and is small at a portion receiving a small clamping force. In the present embodiment, the shrinkage is large at the both end portions in the array direction of the first to third wires  11  to  13  and decreases with an increase in distance from the both end portions. 
         [0051]    As described above, even in such a region that the clamping force of the clamping member  6  would not act when the annular member  5  was not provided, the clamping force of the clamping member  6  is applied by elasticity of the annular member  5  and the braided shield  10  is pressed against the outer surface  41   a  of the accommodating portion  41  of the shield shell  4 . As such, a force of pressing the braided shield  10  against the shield shell  4  is equalized by the annular member  5 , which increases an area of the braided shield  10  on which the clamping force of the clamping member  6  acts. 
         [0052]    Functions and Effects of the Embodiment 
         [0053]    The following functions and effects are obtained in the first embodiment. 
         [0054]    (1) The area of the conductive wires  101  constituting the braided shield  10  on which the clamping force of the clamping member  6  acts is increased by elasticity of the annular member  5 . This allows the braided shield  10  to be more surely in contact with the shield shell  4  as compared to the case of not providing the annular member  5  and suppresses slip-off of the braided shield  10 . 
         [0055]    (2) The annular member  5  is interposed between the braided shield  10  and the clamping member  6 , whereby the braided shield  10  is not directly in contact with the clamping member  6 . Therefore, it is possible to prevent corrosion caused by contact between dissimilar metals. 
         [0056]    (3) The annular member  5  is formed of a tape wound several times so as to surround the braided shield  10  and is thus easily assembled. In addition, since the inner surface of the annular member  5  sticks to the braided shield  10 , slippage of the annular member  5  is suppressed at the time of clamping the clamping member  6  and it is thus possible to easily clamp the clamping member  6 . 
         [0057]    (4) Since the shape of the outer surface  41   a  in a cross section orthogonal to the extending direction of the first to third wires  11  to  13  is a convex arc shape throughout the entire circumference, a force of pressing the braided shield  10  against the shield shell  4  is more equalized than, e.g., the case of the outer surface  41   a  partially having a flat shape or a concave arc shape. 
         [0058]    (5) Since the annular member  5  has the adhesive layer  51  on the back surface  50   a  of the belt-shaped body  50 , an adhesive force acts between the annular member  5  and the shield shell  4  as well as the braided shield  10 . As a result, it is possible to reduce wrinkles of the annular member  5  which are generated at the time of applying the clamping force of the clamping member  6  to the annular member  5 , which allows the braided shield  10  to be more surely in contact with the shield shell  4 . That is, wrinkles generated on the annular member  5  may create a region where the annular member  5  is not appropriately in contact with the conductive wires  101  of the braided shield  10 . However, in the present embodiment, generation of wrinkles is suppressed by the adhesive layer  51  and this allows the braided shield  10  to be more surely in contact with the shield shell  4 . 
         [0059]    Although the embodiment of the invention has been described, the invention according to claims is not to be limited to the above-mentioned embodiment. Further, please note that all combinations of the features described in the embodiment are not necessary to solve the problem of the invention. 
         [0060]    In addition, the invention can be appropriately modified and implemented without departing from the gist of the invention. For example, although the annular member  5  formed by winding a tape has been described in the embodiment, it is not limited thereto and a material of the annular member  5  may be, e.g., rubber or resin. In addition, the clamping member  6  is not limited to a member to be clamped and may be a member to be tightened by a bolt and a nut. In addition, the number of the wires is not limited to three and may be two or four. In addition, the intended purpose of the wire harness  1  is not specifically limited.