Abstract:
A seal structure includes an insertion path which connects between a first opening and a second opening and through which a longitudinal member is inserted; and a seal part, formed at the intermediate section of the insertion path, which contacts with the outer circumference of the inserted longitudinal member. A discharge path is provided on a side wall section of the insertion path, and connects from the side surface of the side wall section to a section, of the insertion path, which is closer to an inflow opening through which flowing water is likely to flow than the seal part is to the inflow opening. The discharge path is structured in communication with a gap, formed between the outer circumference of the longitudinal member and the inner surface of the insertion path, which allows for inflow of flowing water along the direction in which the longitudinal member is inserted

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a seal structure and a control cable unit. 
       BACKGROUND ART 
       [0002]    In a vehicle such as an automobile, a control cable is routed to pass through between the inside and outside of the vehicle in order for a driver inside the vehicle to perform a pulling operation of an operation lever and to transmit the pulling operation to a device outside the vehicle. For this reason, a wall separating the inside and outside of the vehicle needs to have a hole for passing the control cable through the wall, and a structure is also needed in which no dust or water or the like enters from this cable-passing portion of the wall (see, e.g., Patent Literature (hereinafter, referred to “PTL”) 1). Grommets are mostly used for such a structure. 
       CITATION LIST 
     Patent Literature 
     PTL 1 
       [0000]    
       
         Japanese Patent Application Laid-Open No. 2009-68518 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    When misalignment between the axis of a grommet and the axis of a control cable occurs in arrangement of the control cable at the time of mounting to the vehicle, a gap is generated between the grommet and the control cable, and water enters inside the vehicle from the generated gap, however. Even when such misalignment between the axes is prevented, however, high pressure water flowing along the control cable that is exposed outside deforms the grommet and thereby enters from the gap between the grommet and the control cable in a case where the control cable and the grommet are lightly in contact with each other. 
         [0005]    Meanwhile, when an insertion passage of the grommet through which the control cable is inserted is formed so as to tightly hold the control cable, water entry can be prevented. With this configuration, however, insertion of the control cable becomes difficult. 
         [0006]    It is therefore an object of the present invention to provide a seal structure through which a long member such as a control cable is inserted and which seals the long member, and also to provide a control cable unit. This seal structure provided herein prevents water entry without forming an insertion passage for the long member to have a small inner diameter. 
       Solution to Problem 
       [0007]    A seal structure according to an aspect of the present invention is a structure including a long member and a seal member having an insertion portion through which the long member is inserted, in which: the insertion portion includes: a first opening from which the long member is inserted, a second opening from which the long member having been inserted from the first opening extends out, an insertion passage which connects between the first and the second openings and through which the long member is inserted, and an end wall portion which includes an end surface facing an insertion direction of the long member and which is provided with an inflow opening which is one of the first and the second openings and through which flowing water possibly flows in, a side wall portion including a side surface intersecting with the end surface of the end wall portion, and a seal portion formed at a middle portion of the insertion passage and coming into contact with an outer periphery of the inserted long member, in which: the end wall portion is provided to block the flowing water flowing along the insertion direction of the long member from directly hitting the side surface of the side wall portion, the side wall portion is provided with a drain passage connecting the side surface of the side wall portion to a portion in the insertion passage, the portion being closer to the inflow opening than the seal portion is, and the drain passage communicates with a gap which is formed between the outer periphery of the long member and an inner surface of the insertion passage and which is a space through which the flowing water possibly flows in along the insertion direction of the long member. 
       Advantageous Effects of Invention 
       [0008]    According to the present invention, it is made possible to prevent the water having entered between a long member and an insertion passage along a control cable from entering an inner side of a seal. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]      FIG. 1  is a top view illustrating a grommet according to an embodiment of the present invention; 
           [0010]      FIG. 2  is a cross-sectional view taken along line A-A of  FIG. 1 ; 
           [0011]      FIG. 3  is a partially enlarged cross-sectional view of an insertion portion of the grommet in the cross section of  FIG. 2 ; 
           [0012]      FIG. 4  is an explanatory diagram illustrating unevenness provided in a seal portion of  FIG. 3 ; 
           [0013]      FIG. 5  is a partially enlarged view illustrating the insertion portion before insertion of a control cable; 
           [0014]      FIG. 6  is a cross-sectional view taken along line A-A of  FIG. 1  in a case where a direction of a drain passage is changed; 
           [0015]      FIG. 7  is a cross-sectional view taken along line A-A of  FIG. 1  in a case where a direction of the drain passage is changed; and 
           [0016]      FIG. 8  is a cross-sectional view taken along line A-A of  FIG. 1  in a case where a position of the drain passage is changed. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0017]    Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
       Embodiment 
       [0018]      FIG. 1  is a top view illustrating a grommet according to an embodiment of the present invention.  FIG. 2  is a cross-sectional view taken along line A-A of  FIG. 1 . Note that, alternate long and two short dashes lines in the drawings represent control cable  1 . 
         [0019]    A long member refers to control cable  1 , in particular, outer casing  1   o . Control cable  1  includes inner cable  1   i  and outer casing  1   o  covering this inner cable  1   i . However, the long member is not limited to any particular configuration and may be inner cable  1   i , a power transmission line, a communication line, and/or the like, for example. As for the long member, it is possible to employ a member having a predetermined length and disposed to pass through inner and outer sides such as the inside and outside of a vehicle, and it is preferable that an outer peripheral surface of this member be a smooth and flat surface. 
         [0020]    Grommet  2  (corresponding to a seal member) is configured to hold control cable  1  in a state of being attached to a wall or the like that separates the inside and outside of an automobile. Grommet  2  includes body portion  21  and insertion portion  22  provided at this body portion  21 . Note that, grommet  2  is formed of an elastic material (such as ethylene-propylene-diene (EPDM) rubber). However, the material of grommet  2  is not limited to any particular material, and may be, for example, nitrile rubber (NBR) or chloroprene rubber (CR) or the like. In addition, a material obtained by incorporating an elastic material into some part of a non-elastic material may be adopted. In this case, one that is obtained by attaching insertion portion  22  formed of rubber to body portion  21  formed of metal, for example, by baking may be adopted. As an elastic member, any member may be used as long as the member has an elastic function so that the member can come into close contact with outer casing  1   o . In this embodiment, a structure including control cable  1  (long member), and grommet  2  (seal member) having the insertion portion through which control cable  1  is inserted is referred to as a seal structure. 
         [0021]    Body portion  21  refers to a flat and broad portion of grommet  2 . Body portion  21  is formed in a polygonal shape and covers a cable hole provided in the wall separating the inside and outside of the automobile. In addition, body portion  21  is provided with two bolt holes  21   h  and fixed to the wall by bolts passed through these two bolt holes  21   h.    
         [0022]    Insertion portion  22  is a portion where control cable  1  is inserted through, and in this embodiment, insertion portion  22  includes a portion where cylindrical portion  23  is formed in grommet  2 . Cylindrical portion  23  includes insertion passage  23   h  extending in an axial direction of cylindrical portion  23  and holds control cable  1  arranged up to the cable hole and inserted through insertion passage  23   h . In addition, insertion passage  23   h  includes seal portion  24  provided at an inner wall of insertion passage  23   h  and seals control cable  1  by this seal portion  24 . More specifically, insertion passage  23   h  includes seal portion  24  at the inner wall of insertion passage  23   h  and seals an outer periphery of outer casing  1   o  by protruding portions of seal portion  24 . 
         [0023]    Insertion portion  22  includes openings  23   o , and openings  23   o  include first opening  23   o   1  and second opening  23   o   2 . Moreover, insertion portion  22  includes end wall portion  23   t  and side wall portion  23   s . End wall portion  23   t  includes end surface  23   t   1  facing an insertion direction of control cable  1  and is provided on a side of first opening  23   o   1  which is an opening side located outside the vehicle among both openings  23   o . In this embodiment, first opening  23   o   1 , which is the opening located outside the vehicle, is an inflow opening through which flowing water Wt possibly flows in. Accordingly, when flowing water Wt flows along control cable  1  toward first opening  23   o   1 , which is the inflow opening, flowing water Wt hits end surface  23   t   1 . Furthermore, side surface  23   s   1  of side wall portion  23   s  is provided so as to intersect with end surface  23   t   1  of end wall portion  23   t , and end wall portion  23   t  blocks the flowing water that flows along the insertion direction of control cable  1  from directly hitting side wall  23   s   1  of side wall portion  23   s . However, end surface  23   t   1  of end wall portion  23   t  and side surface  23   s   1  of side wall portion  23   s  may be orthogonal to each other or an angle formed by these surfaces may be an acute angle. With this configuration, flowing water Wt mainly hits end surface  23   t   1  of end wall portion  23   t  and thus can be suppressed from directly hitting side surface  23   s   1 , which faces the outside of the vehicle, of side wall portion  23   s  forming at least part of a cylindrical side surface. Moreover, side wall portion  23   s  is provided with drain passage  23   d  for draining the water that has entered insertion passage  23   h.    
         [0024]    Drain passage  23   d  communicates between a portion in insertion passage  23   h  which is closer to the inflow opening than seal portion  24  is, and the outside of side surface  23   s   1  of side wall portion  23   s . More specifically, drain passage  23   d  communicates between a gap formed between the outer periphery of control cable  1  and an inner surface of insertion passage  23   h , and the opening formed in an outer surface of side surface  23   s   1 . Flowing water Wt can flow in this gap along the insertion direction of control cable  1  from first opening  23   o   1 , which is the inflow opening. Drain passage  23   d  drains flowing water Wt that has flown in this gap. Drain passage  23   d  is provided so as to extend in a direction orthogonal to the insertion direction of control cable  1 . As described above, providing drain passage  23   d  allows the water that has entered insertion passage  23   h  to be drained from drain passage  23   d , thus making it possible to reduce pressure in insertion passage  23   h . Accordingly, no water pressure is applied to seal portion  24 , and thus the seal efficiency can be maintained. 
         [0025]    Next, a detailed description will be given of insertion portion  22  using  FIGS. 3 and 4 .  FIG. 3  illustrates insertion portion  22  of grommet  2 .  FIG. 4  illustrates unevenness provided in seal portion  24 . 
         [0026]    As described above, insertion portion  22  includes a portion where cylindrical portion  23  is formed in grommet  2 . Cylindrical portion  23  includes openings  23   o  at both ends thereof (see  FIG. 2 ). Openings  23   o  are each formed to have a size that allows control cable  1  to be inserted, and in this embodiment, each opening  23   o  is formed in a circular shape although it is not limited to any particular shape. In addition, insertion passage  23   h  is formed so as to communicate between first opening  23   o   1  and second opening  23   o   2 . More specifically, cylindrical portion  23  has a shape in which insertion passage  23   h  is formed to pass through a space between one of openings  23   o  and the other one of openings  23   o . In cylindrical portion  23  formed in the manner described above, control cable  1  is inserted from one of openings  23   o , and then inserted control cable  1  passes through insertion passage  23   h  and extends out from the other one of openings  23   o . Insertion passage  23   h  is provided with seal portion  24  at a middle portion of the inner wall thereof and seals an outer periphery of outer casing  1   o  by protruding portions  24   p  of this seal portion  24  in contact with the outer periphery of outer casing  1   o . Seal portion  24  is provided in such a manner that protruding portions  24   p  are axially apart from each other, and seals the outer periphery of outer casing  1   o  so that moisture is prevented from moving along the outer periphery of outer casing  1   o  to an inner side, thereby making it possible to exert waterproofing performance Note that, how insertion passage  23   h  is provided is not limited to any particular manner as long as insertion passage  23   h  is provided to allow control cable  1  to be routed through the inside and outside of an automobile, and in this embodiment, insertion passage  23   h  is formed in a cylindrical shape. 
         [0027]    In this grommet  2 , seal portion  24  includes unevenness, and recess portions  24   c  each provided between protruding portions  24   p  are formed in a ring shape about center axis L of insertion passage  23   h . All recess portions  24   c  have an identical depth. Meanwhile, protruding portions  24   p  of the unevenness are formed in a ring shape about center axis L of insertion passage  23   h . Moreover, protruding portions  24   p  are provided in parallel along insertion passage  23   h . However, it is not necessary that all protruding portions  24   p  have an identical height. More specifically, protruding portions  24   p  in grommet  2  may include two types of protruding portions  24   p , which are one with a higher height and the other with a lower height. In this embodiment, protruding portion  24   p  with a higher height is defined as “first protruding portion  25  (corresponding to primary seal portion)” and protruding portion  24   p  with a lower height is defined as “second protruding portion  26  (corresponding to secondary seal portion).” 
         [0028]    First protruding portions  25  each come into close contact with control cable  1  and seal control cable  1 . More specifically, first protruding portion  25  comes into close contact with outer casing  1   o  of control cable  1 , and thereby seals against moisture such as rain water moving along outer casing  1   o . First protruding portions  25  may have resistance to insertion that does not deteriorate the insertability of grommet for outer casing to and may be configured to have a shape capable of coming into close contact with an outer shape of outer casing  1   o . Note that, the term “come into close contact with” means a state where first protruding portion  25  having elastically deformed presses hard against an outer periphery of outer casing  1   o , so that the pressure of the contact portion increases. In terms of functionality, this term means a state where it is possible to surely seal against moisture such as rain water. Note that, since first protruding portions  25  have a role of sealing against moisture such as rain water, first protruding portions  25  are always formed in a circumferentially ring shape and do not include a spiral. 
         [0029]    In first protruding portion  25 , a cross-sectional shape of base portion  25   b  is substantially rectangular. Furthermore, top portion  25   a  has a substantially wedge shape in which top portion  25   a  is tapered as a cross-sectional shape of top portion  25   a  nears center line L. More specifically, the cross-sectional shape of first protruding portion  25  extends perpendicularly toward center line L from a bottom of recess portion  24   c  and is tapered starting from a predetermined height. This shape is adopted for the purpose of adequately suppressing rigidity of a root portion and of reducing a contact area with control cable  1 . This increases flexibility of first protruding portion  25  and simultaneously achieves an improvement in the sealing function. Meanwhile, the flexibility of first protruding portion  25  can be increased by forming recess portion  24   c  with a greater depth. Note that, inner diameter φx of top portion  25   a  of first protruding portion  25  is between 99% and 65% of outer diameter φc of control cable  1  (see  FIG. 5 ). The numerical value of inner diameter φx is calculated by the following expression. 
         [0000]      φ x/φc× 100=99 to 65(%)  Expression:
 
         [0030]    A ratio of inner diameter φx to outer diameter φc can be practically within a range of 65% to 99% both inclusive. However, in order to improve workability while securing the seal efficiency, the ratio is preferably within a range of 87% to 95% both inclusive. 
         [0031]    Note that, the term “top portion” means a portion around a top of first protruding portion  25 , which is closest to an axis side in a portion of first protruding portion  25  protruding in the axial direction of insertion passage  23   h . This portion is a portion which comes into contact with the outer periphery of outer casing  1   o  and where elastic deformation of first protruding portion  25  occurs at the time of insertion of control cable  1 . In this embodiment, as described above, this portion is configured to have a protruding shape, and in cases of first protruding portions  25  as well as second protruding portions  26  to be described hereinafter, the inner diameter is defined with reference to a leading end of the protruding portion. 
         [0032]    Second protruding portions  26  each come into contact with control cable  1  and seal control cable  1 . More specifically, second protruding portion  26  comes into contact with outer casing  1   o  of control cable  1 , and thereby seals against moisture such as rain water moving along outer casing  1   o . Note that, the term “come into contact with” means a state where second protruding portion  26  having elastically deformed lightly presses against the outer periphery of outer casing  1   o , so that the pressure of the contact portion somewhat increases. In terms of functionality, this term means a state where it is possible to auxiliary seal against moisture such as rain water while insertion of control cable  1  is made easy. Note that, since second protruding portions  26  have a role of sealing against moisture such as rain water, second protruding portions  26  are preferentially formed in a circumferentially ring shape about center axis L of insertion passage  23   h . However, as long as first protruding portions  25  can secure the sealing function, second protruding portions  26  are not necessarily formed in a ring shape. 
         [0033]    In second protruding portion  26 , a cross-sectional shape of base portion  26   b  is substantially rectangular. Furthermore, top portion  26   a  has a substantially wedge shape in which top portion  26   a  is tapered as a cross-sectional shape of top portion  26   a  nears center line L. More specifically, the cross-sectional shape of second protruding portion  26  extends perpendicularly toward center axis L from a bottom of recess portion  24   c  and is tapered starting from a predetermined height. This shape is adopted for the purpose of adequately suppressing rigidity of a root portion and of reducing the contact area with control cable  1 . This increases flexibility of second protruding portion  26  and simultaneously achieves an improvement in the sealing function. Meanwhile, the flexibility of second protruding portion  26  can be increased by forming recess portion  24   c  with a greater depth. Regarding the height of second protruding portion  26  from the bottom of recess portion  24   c  of second protruding portion  26 , second protruding portion  26  is configured to have a height that allows second protruding portion  26  to come into contact with the outer periphery of outer casing  1   o  which is a direct seal target and configured not to generate resistance to insertion and not to elastically deform at the time of insertion of control cable  1  by setting inner diameter φy of second protruding portion  26  to be larger than inner diameter φx of first protruding portion  25 . Note that, inner diameter φy of top portion  26   a  of second protruding portion  26  is between 100 percent and 92 percent of outer diameter φc of control cable  1  (see  FIG. 5 ). This numerical value of the inner diameter φy is calculated by the following expression. 
         [0000]      φ y/φc× 100=100 to 92(%)  Expression:
 
         [0034]    In this embodiment, while outer diameter φc of outer casing  1   o  is 7.1 mm, inner diameter φx of first protruding portion  25  is set to 6.4 mm, and inner diameter φy of second protruding portion  26  is set to 6.8 mm 
         [0035]    As described above, drain passage  23   d  is provided in the seal structure of this embodiment. This drain passage  23   d  connects between side surface  23   s   1  of side wall portion  23   s  that forms insertion passage  23   h  and a portion in insertion passage  23   h  which is closer to the inflow opening than seal portion  24  is. This structure allows the water that has entered insertion passage  23   h  to be drained from drain passage  23   d  to reduce pressure in insertion passage  23   h  and thereby prevents seal portion  24  from being applied with water pressure, thus making it possible to maintain the sealing efficiency. For this reason, it is made possible to prevent the water that has entered between control cable  1  and insertion passage  23   h  from entering an inner side of seal portion  24  without forming insertion passage  23   h  to have a small inner diameter. 
         [0036]    &lt;Variation&gt; 
         [0037]    In the embodiment described above, a case has been described where the drain passage is provided so as to extend orthogonally to the insertion direction of control cable  1 . The present invention is not limited to this case, however. As illustrated in  FIG. 6 , for example, drain passage  23   d  may be provided such that angle θ 1  formed by direction f 1  of the drain passage in a direction from a side of insertion passage  23   h  toward a side of side surface  23   s   1  and direction f 2  of insertion passage  23   h  in a direction from a side of inflow opening  23   o  toward a side of opening  23   o  at the other end is an acute angle. 
         [0038]    Moreover, as illustrated in  FIG. 7 , for example, drain passage  23   d  may be provided such that angle θ 2  formed by direction f 1  of the drain passage in the direction from a side of insertion passage  23   h  toward a side of side surface  23   s   1  and direction f 2  of insertion passage  23   h  in the direction from a side of inflow opening  23   o  toward a side of opening  23   o  at the other end is an obtuse angle. 
         [0039]    In the embodiment described above, a case has been described where drain passage  23   d  is connected to insertion passage  23   h  at a position closer to the inflow opening than seal portion  24  that is closest to the inflow opening is. The present invention is not limited to this case, however. More specifically, as illustrated in  FIG. 8 , drain passage  23   d  ( 23   d   1 ,  23   d   2 ) may be connected to a portion in insertion passage  23   h  that is closer to the inflow opening than at least one of a plurality of protruding portions  24   p  forming seal portion  24  is. 
         [0040]    In the embodiment described above, the case has been described where drain passage  23   d  is connected to insertion passage  23   h  at a position closer to the inflow opening than seal portion  24  that is closest to the inflow opening is. The present invention is not limited to this case, however. More specifically, drain passage  23   d  may be connected to insertion passage  23   h  at a position closer to the inflow opening than at least one of a plurality of primary seal portions is. 
       INDUSTRIAL APPLICABILITY 
       [0041]    The present invention is applicable to a seal structure and a control cable unit. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1  Control cable (long member) 
           1   i  Inner cable 
           1   o  Outer casing 
           2  Grommet (elastic member) 
           21  Body portion 
           22  Insertion portion 
           23  Cylindrical portion 
           23   t  End wall portion 
           23   s  Side wall portion 
           23   d  Drain passage 
           23   h  Insertion passage 
           24  Seal portion 
           24   c  Recess portion 
           24   p  Protruding portion 
           25  First protruding portion 
           26  Second protruding portion 
         Wt Flowing water 
         φx Inner diameter of top portion of first protruding portion 
         φy Inner diameter of top portion of second protruding portion 
         φc Outer diameter of control cable