Patent Publication Number: US-2023162893-A1

Title: Grommet

Description:
TECHNICAL FIELD 
     The present disclosure relates to a grommet. 
     BACKGROUND 
     Conventionally, there are cases in which a grommet is used to waterproof an insertion hole provided in a vehicle body panel when a wire harness is inserted into the insertion hole. Such a grommet includes an annular mounting portion that is to be fixed to a portion around the insertion hole of the vehicle body panel, and a tubular insertion portion that comes into contact with the outer circumferential surface of the wire harness and covers the outer circumference of the wire harness. Furthermore, the mounting portion includes an annular seal portion that comes into close contact with a surrounding portion of the insertion hole of the vehicle body panel or with the inner circumferential surface of the insertion hole. 
     For example, the grommet disclosed in Patent Document 1 includes a flexible portion that connects a mounting portion and an insertion portion so as to close off the space between the mounting portion and the insertion portion. The flexible portion is provided so as to extend to the inner circumferential rim portion of the mounting portion from one of two axial end portions of the insertion portion that is located on the vehicle-body-panel side when the grommet is mounted to a vehicle body panel. Furthermore, the flexible portion is formed from one pleat that has a shape resembling a mountain protruding toward the opposite side from the vehicle body panel in a state in which the grommet is mounted to the vehicle body panel. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: JP 2016-210214 A 
     SUMMARY OF THE INVENTION 
     Problems to be Solved 
     Incidentally, a wire harness may be inserted into an insertion hole in a state in which the wire harness is inclined with respect to the insertion hole. Furthermore, in a vehicle, there may be an error in the arrangement position of a wire harness. In such cases, the insertion portion of a grommet may be pulled strongly away from the mounting portion of the grommet in the axial direction of the mounting portion, or may be significantly inclined with respect to the mounting portion. In such situations, the mounting portion may also deform due to the connection portion not being able to absorb the stress caused by the change in posture and position of the insertion portion solely by itself. If the mounting portion deforms, a gap may form between the mounting portion and the vehicle body panel. If a gap is formed between the mounting portion and the vehicle body panel, water may enter via the gap, and thus there is a concern that the waterproofing performance of the grommet may decrease. 
     In view of this, in the grommet disclosed in Patent Document 1 for example, it is conceivable to increase the number of pleats in a flexible portion in order for the flexible portion to absorb large amounts of stress generated by the insertion portion moving relative to the mounting portion. However, if a configuration is adopted in which the flexible portion has a plurality of pleats that are arranged in a direction that is orthogonal to the center axis of the mounting portion, the size of the grommet would increase in the direction that is orthogonal to the center axis of the mounting portion. An increase in grommet size is not desirable because space for disposing a grommet in a vehicle is limited. Thus, there is a demand to suppress a decrease in the waterproofing performance of a grommet while suppressing an increase in the size of the grommet. 
     An object of the present disclosure is to provide a grommet with which a decrease in waterproofing performance can be suppressed while suppressing an increase in size. 
     Means to Solve the Problem 
     A grommet according to the present disclosure is a grommet including: an annular mounting portion that is to be fixed to a surrounding portion of an insertion hole of an object to which the grommet is to be attached and which includes the insertion hole; a tubular stress-absorbing portion that includes a tubular side wall that extends from an inner circumferential rim portion of the mounting portion toward one side in an axial direction of the mounting portion, and a bottom wall that partially closes off the tubular side wall at a front end of the tubular side wall; and a tubular insertion portion that is provided integrally with the bottom wall, and that comes into contact with an the outer circumferential surface of a wire harness inserted into the insertion hole and covers the outer circumference of the wire harness, wherein the mounting portion includes an annular seal portion that comes into close contact with the surrounding portion of the insertion hole of the object to which the grommet is to be attached, or with an inner circumferential surface of the insertion hole, the side wall is flexible, and the insertion portion protrudes inside the stress-absorbing portion from the bottom wall toward the base-end side of the side wall. 
     Effect of the Invention 
     According to the grommet according to the present disclosure, a decrease in waterproofing performance can be suppressed while suppressing an increase in size. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a cross-sectional view of a grommet mounted to a vehicle body panel in one embodiment. 
         FIG.  2    is a perspective view of the grommet in one embodiment. 
         FIG.  3    is a cross-sectional view of the grommet in one embodiment. 
         FIG.  4    is a plan view of the grommet in one embodiment. 
         FIG.  5    is a cross-sectional view of a grommet in a modification. 
     
    
    
     DETAILED DESCRIPTION TO EXECUTE THE INVENTION 
     Description of Embodiments of Present Disclosure 
     First, aspects of the present disclosure will be listed and described. 
     [1] A grommet according to the present disclosure is a grommet including: an annular mounting portion that is to be fixed to a surrounding portion of an insertion hole of an object to which the grommet is to be attached and which includes the insertion hole; a tubular stress-absorbing portion that includes a tubular side wall that extends from an inner circumferential rim portion of the mounting portion toward one side in an axial direction of the mounting portion, and a bottom wall that partially closes off the tubular side wall at a front end of the tubular side wall; and a tubular insertion portion that is provided integrally with the bottom wall, and that comes into contact with an outer circumferential surface of a wire harness inserted into the insertion hole and covers the outer circumference of the wire harness, wherein the mounting portion includes an annular seal portion that comes into close contact with the surrounding portion of the insertion hole of the object to which the grommet is to be attached, or with an inner circumferential surface of the insertion hole, the side wall is flexible, and the insertion portion protrudes inside the stress-absorbing portion from the bottom wall toward the base-end side of the side wall. 
     According to this configuration, the insertion portion is provided integrally with the bottom wall of the stress-absorbing portion. Furthermore, the side wall of the stress-absorbing portion is flexible. Thus, if the insertion portion moves relative to the mounting portion due to an error in the arrangement position of the wire harness, a difference in lengths of wire harnesses, etc., the stress generated by the relative movement can be absorbed by the side wall bending. In this way, the stress that is generated by the insertion portion moving relative to the mounting portion is absorbed by the side wall, which extends from the inner circumferential rim portion of the mounting portion toward one side in the axial direction of the mounting portion. Accordingly, transmission, to the mounting portion, of the stress generated by the insertion portion moving relative to the mounting portion can be suppressed without an increase in the size of the grommet in a direction that is orthogonal to the axial direction of the mounting portion. Furthermore, because deformation of the mounting portion when the insertion portion moves relative to the mounting portion can be suppressed, deformation of the seal portion can be suppressed. Thus, a decrease in the waterproofing performance of the grommet can be suppressed while suppressing an increase in the size of the grommet. 
     In addition, the insertion portion is provided integrally with the bottom wall of the stress-absorbing portion. Furthermore, the insertion portion protrudes inside the stress-absorbing portion from the bottom wall toward the base-end side of the side wall. Thus, an increase in the size of the grommet in the axial direction of the side wall can be suppressed compared to a case in which the entire insertion portion protrudes to the outside of the stress-absorbing portion. Accordingly, an increase in the size of the grommet in the axial direction of the side wall can be suppressed even if the side wall extends from the inner circumferential rim portion of the mounting portion toward one side in the axial direction of the mounting portion. 
     [2] Preferably, the insertion portion has a portion that overlaps the side wall in a direction that is orthogonal to a center axis of the insertion portion in a cross-section taken along a plane including the center axis of the insertion portion. 
     According to this configuration, an insertion portion that protrudes toward the base-end side of the side wall inside the stress-absorbing portion can be easily provided. 
     [3] Preferably, the side wall includes a plurality of pleat portions that extend along a direction that intersects a center axis of the side wall when seen from a direction that is orthogonal to an axial direction of the side wall, and the plurality of pleat portions are displaced from one another in the axial direction of the side wall. 
     According to this configuration, the plurality of pleat portions are displaced from one another in the axial direction of the side wall. Thus, a plurality of pleat portions can be provided in the stress-absorbing portion while suppressing an increase in the size of the stress-absorbing portion in a direction that is orthogonal to the axial direction of the mounting portion compared to a case in which a plurality of pleat portions are arranged in the direction that is orthogonal to the axial direction of the mounting portion. Furthermore, the stress generated by the insertion portion moving relative to the mounting portion can be more readily absorbed by the side wall including the plurality of pleat portions due to the pleat portions deforming in an expanding or contracting fashion. Accordingly, because deformation of the mounting portion when the insertion portion moves relative to the mounting portion can be suppressed to a greater degree, deformation of the seal portion can be suppressed to a greater degree. Thus, a decrease in the waterproofing performance of the grommet can be suppressed to a greater degree. 
     [4] Preferably, the pleat portions each have an annular shape encircling the center axis of the side wall, and the plurality of pleat portions are arranged from the mounting-portion side toward the bottom-wall side and form a bellows portion in which adjacent ones of the pleat portions are continuously connected. 
     According to this configuration, the plurality of pleat portions in the side wall form a bellows portion. Thus, in addition to the plurality of pleat portions deforming in an expanding or contracting fashion, portions between adjacent pleat portions can also deform in an expanding or contracting fashion. Accordingly, the stress generated by the insertion portion moving relative to the mounting portion can be more readily absorbed by the side wall including the bellows portion. Hence, because deformation of the mounting portion when the insertion portion moves relative to the mounting portion can be suppressed to a greater degree, deformation of the seal portion can be suppressed to a greater degree. Thus, a decrease in the waterproofing performance of the grommet can be suppressed to a greater degree. Furthermore, because the side wall allows the insertion portion to move even more relative to the mounting portion, a decrease in the waterproofing performance of the grommet can be suppressed even more. 
     [5] Preferably, the entire insertion portion is positioned closer to the mounting portion than an outer surface of the bottom wall is in the axial direction of the mounting portion. 
     According to this configuration, an increase in the size of the grommet in the axial direction of the mounting portion can be more readily suppressed compared to a case in which the insertion portion has a portion that protrudes from the bottom wall to the outside of the stress-absorbing portion. Accordingly, an increase in the size of the grommet in the axial direction of the mounting portion can be suppressed more readily even if the side wall extends from the inner circumferential rim portion of the mounting portion toward one side in the axial direction of the mounting portion. 
     Details of Embodiments of Present Disclosure 
     Specific examples of the grommet according to the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, and is intended to include all modifications that are indicated by the claims and are within the meaning and scope of equivalents of the claims. 
     One embodiment of the grommet will be described below. Note that some components may be exaggerated or simplified in the attached drawings for the sake of description. Also, the dimensional ratio of some parts may differ from their actual ratio. 
     A grommet  20  according to the present embodiment illustrated in  FIG.  1    is for waterproofing an insertion hole  12  that is formed in a vehicle body panel  11  that partitions the interior and the exterior of an automobile. Specifically, the grommet  20  is for ensuring waterproofness between the insertion hole  12  and wire harnesses  13  and  14  that are inserted into the insertion hole  12 . Furthermore, the grommet  20  also fulfills the role of protecting the wire harnesses  13  and  14 . 
     For example, the vehicle body panel  11  is a panel that partitions an underfloor space and an engine room of the vehicle. The insertion hole  12  extends through the vehicle body panel  11 . In the present embodiment, the insertion hole  12  has a circular shape when seen from the direction in which the insertion hole  12  extends. 
     Configuration of Grommet  20   
     As illustrated in  FIGS.  1  and  2   , the grommet  20  includes an annular mounting portion  21  that is to be fixed to a surrounding portion of the insertion hole  12  of the vehicle body panel  11 , and a stress-absorbing portion  22  that is provided integrally with the inner circumferential rim portion of the mounting portion  21 . Furthermore, the grommet  20  includes a tubular first insertion portion  23  and a tubular second insertion portion  24  that respectively cover the outer-circumferential surfaces of the wire harness  13  and the wire harness  14  inserted into the insertion hole  12 . The grommet  20  is made of a flexible material. For example, an elastomer, such as highly-flexible ethylene propylene diene monomer (EPDM) rubber, can be used as the material of the grommet  20 . 
     Configuration of Mounting Portion  21   
     As illustrated in  FIGS.  1 ,  2 , and  4   , the mounting portion  21  has an annular shape with a circular outer shape. Note that, in the following, a direction that is parallel with a center axis L 1  of the mounting portion  21 , or in other words an axial direction of the mounting portion  21 , is referred to as an axial direction X 1 . Furthermore, the term “radial direction” or “radially”, when used independently, indicates a radial direction of the mounting portion  21  that is orthogonal to the center axis L 1 . Also, the term “circumferential direction”, when used independently, indicates a circumferential direction of the mounting portion  21  about the center axis L 1 . 
     The inner circumferential rim portion of the mounting portion  21  has an oval shape that is concentric with the outer shape of the mounting portion  21  when seen from the axial direction X 1 . The outer diameter of the mounting portion  21  is larger than the inner diameter of the insertion hole  12 . When the grommet  20  is mounted to the vehicle body panel  11 , the mounting portion  21  faces a surrounding portion of the insertion hole  12  of the vehicle body panel  11 . 
     As illustrated in  FIGS.  1  and  3   , the mounting portion  21  includes a seal portion  31  on one surface thereof in the axial direction X 1 . This surface is the surface of the mounting portion  21  that faces the vehicle body panel  11  in the axial direction X 1  when the grommet  20  is mounted to the vehicle body panel  11 . When the grommet  20  is mounted to the vehicle body panel  11 , the seal portion  31  comes into close contact with the surrounding portion of the insertion hole  12  of the vehicle body panel  11 . Note that  FIG.  3    is a cross-sectional view taken along line  3 - 3  in  FIG.  4   . 
     The seal portion  31  includes a first lip portion  32  and a second lip portion  33 . The first lip portion  32  and the second lip portion  33  each protrude in the axial direction X 1  from the one surface of the mounting portion  21  facing the vehicle body panel  11  in the axial direction X 1 . Furthermore, the first lip portion  32  and the second lip portion  33  each form a protrusion that extends continuously along the circumferential direction. The first lip portion  32  has an annular shape that is slightly larger than the inner diameter of the insertion hole  12 . The second lip portion  33  has an annular shape that is slightly larger than the first lip portion  32 . In a cross-section of the grommet  20  taken along a plane including the center axis L 1 , the first lip portion  32  and the second lip portion  33  are arranged in the radial direction. Note that the cross-sectional views of the grommet  20  shown in  FIGS.  1  and  3    are cross-sectional views of the grommet  20  taken along a plane including the center axis L 1 . 
     Configuration of Stress-Absorbing Portion  22   
     As illustrated in  FIGS.  1  to  3   , the stress-absorbing portion  22  has a tubular shape and includes a tubular side wall  41  that extends from the inner circumferential rim portion of the mounting portion  21  toward one side in the axial direction X 1 , and a bottom wall  42  that partially closes off the side wall  41  at the front end of the side wall  41 . The side wall  41  and the bottom wall  42  are flexible. 
     The side wall  41  extends from the inner circumferential rim portion of the mounting portion  21  in the direction away from the vehicle body panel  11  when the grommet  20  is attached to the vehicle body panel  11 , or in other words, in the opposite direction from the direction in which the first lip portion  32  and the second lip portion  33  protrude from the mounting portion  21 . In the present embodiment, the side wall  41  is formed coaxially with the mounting portion  21 . That is, a center axis L 2  of the side wall  41  is positioned on the same straight line as the center axis L 1  of the mounting portion  21 . Thus, the axial direction of the side wall  41  is the same direction as the axial direction X 1 . 
     The side wall  41  includes a tubular first tubular portion  51  that extends along the axial direction X 1  from the inner circumferential rim portion of the mounting portion  21 , a second tubular portion  52  that is positioned on the opposite axial end portion of the side wall  41  from the first tubular portion  51 , and a bellows portion  53  that is provided so as to connect the first tubular portion  51  and the second tubular portion  52 . Note that the first tubular portion  51  and the second tubular portion  52  respectively form the base end portion and the front end portion of the side wall  41 . 
     As illustrated in  FIG.  4   , when seen from the axial direction X 1 , the first tubular portion  51  is formed in a tubular shape that has an oval shape corresponding to the inner circumferential rim portion of the mounting portion  21 . The second tubular portion  52  has a tubular shape whose outer shape is smaller than the outer shape of the first tubular portion  51 . Thus, the outer shape of the end portion of the stress-absorbing portion  22  that is located on the bottom-wall- 42  side is smaller than the outer shape of the end portion of the stress-absorbing portion  22  that is located on an opening side of the stress-absorbing portion  22 . When seen from the axial direction X 1 , the second tubular portion  52  is positioned radially inward of the first tubular portion  51 . The second tubular portion  52  is formed in a tubular shape having a rounded rectangular shape (in other words, the shape of a race track) when seen from the axial direction X 1 . Note that the first tubular portion  51  and the second tubular portion  52  are formed so as to be concentric when seen from the axial direction X 1 . 
     As illustrated in  FIGS.  2  to  4   , the bottom wall  42  closes off the end portion of the second tubular portion  52  on the opposite side from the bellows portion  53 . The bottom wall  42  has the shape of a plate that is orthogonal to the axial direction X 1 . When seen from the axial direction X 1 , the bottom wall  42  has the shape of a rounded rectangle corresponding to the shape of the front end portion of the side wall  41 . 
     The bellows portion  53  includes a plurality of first wall portions  54  that are inclined with respect to the center axis L 2 , and a plurality of second wall portions  55  that are inclined with respect to the center axis L 2  at an angle that is different from that of the first wall portions  54 . In the present embodiment, the bellows portion  53  includes four first wall portions  54  and also includes four second wall portions  55 . The first wall portions  54  and the second wall portions  55  each have an annular shape encircling the center axis L 2 . In the present embodiment, the first wall portions  54  and the second wall portions  55  each have an oval shape or a rounded rectangular shape when seen from the axial direction X 1 . In a cross-section of the grommet  20  taken along a plane including the center axis L 2 , the first wall portions  54  and the second wall portions  55  are arranged alternately from the mounting-portion- 21  side toward the bottom-wall- 42  side. That is, the first wall portions  54  and the second wall portions  55  are arranged alternately along the direction of the center axis L 2 , or in other words, along the axial direction of the side wall  41 . 
     Here, the four first wall portions  54  are referred to as first wall portions  54   a,    54   b,    54   c,  and  54   d  in order from the one positioned on the base-end side of the side wall  41 . Furthermore, the four second wall portions  55  are referred to as second wall portions  55   a,    55   b,    55   c,  and  55   d  in order from the one positioned on the base-end side of the side wall  41 . The four first wall portions  54  and the four second wall portions  55  are arranged from the base-end side toward the front-end side of the side wall  41  in the order of the first wall portion  54   a,  the second wall portion  55   a,  the first wall portion  54   b,  the second wall portion  55   b,  the first wall portion  54   c,  the second wall portion  55   c,  the first wall portion  54   d,  and the second wall portion  55   d.  The first wall portion  54   a  extends from the end portion of the first tubular portion  51  on the opposite side from the mounting portion  21  in the axial direction X 1 . Furthermore, the second wall portion  55   d  extends from the end portion of the second tubular portion  52  on the opposite side from the bottom wall  42  in the axial direction X 1 . 
     The first wall portions  54   a  to  54   d  are each inclined with respect to the center axis L 2  so that the diameter thereof increases as they approach the bottom wall  42  along the axial direction of the side wall  41  (the same direction as the axial direction X 1  in the present embodiment). On the other hand, the second wall portions  55   a  to  55   d  are each inclined with respect to the center axis L 2  so that the diameter thereof decreases as they approach the bottom wall  42  along the axial direction of the side wall  41 . In this way, the first wall portions  54  and the second wall portions  55  are inclined in opposite directions. Furthermore, in regard to a first wall portion  54  and a second wall portion  55  that are adjacent to one another in the axial direction of the side wall  41 , an end portion of the first wall portion  54  on one side in the axial direction of the side wall  41  and an end portion of the second wall portion  55  on the other side in the axial direction of the side wall  41  are connected to one another. 
     A first wall portion  54  and a second wall portion  55  that are adjacent to one another in the axial direction of the side wall  41  form a pleat portion  56  that extends along a direction that intersects the center axis L 2  when seen from a direction that is orthogonal to the axial direction of the side wall  41 . Specifically, a pleat portion  56   a  is formed by the first wall portion  54   a  positioned closest to the mounting portion  21  and the second wall portion  55   a,  which is positioned between the first wall portion  54   a  and the bottom wall  42  and is adjacent to the first wall portion  54   a  in the axial direction of the side wall  41 . The first wall portion  54   a  and the second wall portion  55   a  form an annular groove that is open toward the inside of the side wall  41 , and also form an annular protrusion that protrudes toward the outside of the side wall  41 . Thus, the pleat portion  56   a  has a shape in which a groove that extends in the same direction as the protrusion is included behind the protrusion. Note that, in the present embodiment, the pleat portion  56   a  extends in a direction that is orthogonal to the center axis L 2  when seen from a direction that is orthogonal to the axial direction of the side wall  41 . Furthermore, in the present embodiment, a cross-section of the pleat portion  56   a  taken along a plane including the center axis L 2 , or in other words, a cross-section of the pleat portion  56   a  taken along a plane that is orthogonal to the circumferential direction, has a V-shape. Furthermore, the pleat portion  56   a  extends continuously without any breaks so as to encircle the center axis L 2 , and has an oval shape when seen from the axial direction of the side wall  41 . That is, the pleat portion  56   a  has an annular shape encircling the center axis L 2 . 
     Similarly, the first wall portion  54   b  and the second wall portion  55   b  adjacent to one another in the axial direction of the side wall  41  form a pleat portion  56   b  that is similar to the pleat portion  56   a.  Also, the first wall portion  54   c  and the second wall portion  55   c  adjacent to one another in the axial direction of the side wall  41  form a pleat portion  56   c  that is similar to the pleat portion  56   a.  In addition, the first wall portion  54   d  and the second wall portion  55   d  adjacent to one another in the axial direction of the side wall  41  form a pleat portion  56   d  that is similar to the pleat portion  56   a.  Furthermore, the pleat portion  56   a,  the pleat portion  56   b,  the pleat portion  56   c,  and the pleat portion  56   d  are arranged in this order from the mounting-portion- 21  side toward the bottom-wall- 42  side. The pleat portions  56   a  to  56   d  are displaced from one another in the axial direction of the side wall  41 . 
     Furthermore, because ends, in the axial direction X 1 , of the second wall portion  55   a  and the first wall portion  54   b  adjacent to one another in the axial direction of the side wall  41  are connected to one another, the pleat portion  56   a  and the pleat portion  56   b  adjacent to one another in the axial direction of the side wall  41  are provided so as to be continuous. Similarly, because ends, in the axial direction X 1 , of the second wall portion  55   b  and the first wall portion  54   c  adjacent to one another in the axial direction of the side wall  41  are connected to one another, the pleat portion  56   b  and the pleat portion  56   c  adjacent to one another in the axial direction of the side wall  41  are provided so as to be continuous. Also, because ends, in the axial direction X 1 , of the second wall portion  55   c  and the first wall portion  54   d  adjacent to one another in the axial direction of the side wall  41  are connected to one another, the pleat portion  56   c  and the pleat portion  56   d  adjacent to one another in the axial direction of the side wall  41  are provided so as to be continuous. Furthermore, the bellows portion  53 , in which adjacent pleat portions  56  are continuously connected, is formed by these pleat portions  56   a  to  56   d.    
     Among the plurality of pleat portions  56 , the closer a pleat portion  56  is to the bottom wall  42  in a cross-section of the grommet  20  taken along a plane including the center axis L 2 , the shorter the length of the pleat portion  56  in a direction that is orthogonal to the center axis L 2  is. Note that the length of a pleat portion  56  in a direction that is orthogonal to the center axis L 2  in a cross-section of the grommet  20  taken along a plane including the center axis L 2  corresponds to the left-right direction length of the pleat portion  56  in  FIG.  3   . 
     Configuration of Insertion Portions  23  and  24   
     As illustrated in  FIG.  1   , the first insertion portion  23  and the second insertion portion  24  are provided integrally with the bottom wall  42 . When seen from the axial direction of the side wall  41 , the first insertion portion  23  and the second insertion portion  24  are arranged in the longitudinal direction of the bottom wall  42 . The first insertion portion  23  and the second insertion portion  24  each have a cylindrical shape extending along the axial direction of the side wall  41 . In the present embodiment, the first insertion portion  23  and the second insertion portion  24  each have a cylindrical shape extending along the axial direction X 1 . In addition, the first insertion portion  23  and the second insertion portion  24  each protrude inside the stress-absorbing portion  22  from the bottom wall  42  toward the base-end portion side of the side wall  41 . Furthermore, in a cross-section of the grommet  20  taken along a plane including a center axis L 3  of the first insertion portion  23 , the first insertion portion  23  overlaps the side wall  41  in a direction that is orthogonal to the center axis L 3 . In a cross-section of the grommet  20  taken along a plane including a center axis L 4  of the second insertion portion  24 , the second insertion portion  24  overlaps the side wall  41  in a direction that is orthogonal to the center axis L 4 . Note that the cross-sections of the grommet  20  illustrated in  FIGS.  1  and  3    are cross-sections that are taken along a plane including the center axis L 3  and are also cross-sections that are taken along a plane including the center axis L 4 . The entire first insertion portion  23  is positioned closer to the mounting portion  21  than an outer surface  42   a  of the bottom wall  42  is in the axial direction X 1 . The entire second insertion portion  24  is positioned closer to the mounting portion  21  than the outer surface  42   a  of the bottom wall  42  is in the axial direction X 1 . 
     The first insertion portion  23  comes into contact with the outer circumferential surface of the wire harness  13  inserted into the first insertion portion  23  and covers the outer circumference of the wire harness  13 . Furthermore, the second insertion portion  24  comes into contact with the outer circumferential surface of the wire harness  14  inserted into the second insertion portion  24  and covers the outer circumference of the wire harness  14 . 
     As illustrated in  FIG.  3   , a flange portion  23   a  that protrudes from the outer circumference of the first insertion portion  23  is provided at the front end portion of the first insertion portion  23 , or more specifically, the front end portion of the portion of the first insertion portion  23  protruding inside the stress-absorbing portion  22 . The flange portion  23   a  forms a protrusion that extends along the circumferential direction about the center axis L 3 . Similarly, a flange portion  24   a  that protrudes from the outer circumference of the second insertion portion  24  is provided at the front end portion of the second insertion portion  24 , or more specifically, the front end portion of the portion of the second insertion portion  24  protruding inside the stress-absorbing portion  22 . The flange portion  24   a  forms a protrusion that extends along the circumferential direction about the center axis L 4 . In the present embodiment, the flange portions  23   a  and  24   a  are toric in shape. 
     A fixing member  61  suppresses relative movement between the first insertion portion  23  and the wire harness  13  inserted into the first insertion portion  23 , in the center axis L 3  direction. For example, the fixing member  61  is a piece of adhesive tape that is wrapped around the outer circumferential surfaces of the first insertion portion  23  and the wire harness  13 , a zip tie that is attached to the outer circumferential surface of the first insertion portion  23 , or the like. In the present embodiment, the fixing member  61  is a piece of adhesive tape. When attaching the fixing member  61  to the first insertion portion  23  and the wire harness  13 , the first insertion portion  23  is moved toward the opening of the stress-absorbing portion  22  as a result of being pulled toward the mounting portion  21 . At this time, the first insertion portion  23  can be easily moved toward the opening of the stress-absorbing portion  22  due to bending of the side wall  41 . In this state, the fixing member  61  is attached to the first insertion portion  23  and the wire harness  13 . Note that, when the wrapping of the fixing member  61 , which is a piece of adhesive tape, around the first insertion portion  23  is begun, the flange portion  23   a  is used to position an end portion of the fixing member  61  relative to the first insertion portion  23  in the center axis L 3  direction. 
     A fixing member  62  similar to the fixing member  61  suppresses relative movement between the second insertion portion  24  and the wire harness  14  inserted into the second insertion portion  24 , in the center axis L 4  direction. The fixing member  62  is attached to the second insertion portion  24  and the wire harness  14  in the same manner as the fixing member  61  is attached to the first insertion portion  23  and the wire harness  13 . Furthermore, when the wrapping of the fixing member  62 , which is a piece of adhesive tape, around the second insertion portion  24  is begun, the flange portion  24   a  is used to position an end portion of the fixing member  62  relative to the second insertion portion  24  in the center axis L 4  direction. 
     Configuration of Bracket  71   
     As illustrated in  FIG.  1   , the grommet  20  is attached to the vehicle body panel  11  using a bracket  71  that is to be fixed to the vehicle body panel  11 . The bracket  71  is made using a metal plate member. The bracket  71  includes an annular sandwiching portion  72  and fixing portions  73  that are provided integrally with the sandwiching portion  72  in the outer circumferential rim of the sandwiching portion  72 . 
     The outer diameter of the sandwiching portion  72  is larger than the inner diameter of the insertion hole  12 . The fixing portions  73  are provided in the outer circumferential rim portion of the sandwiching portion  72  at a plurality of positions that are separated from one another in the circumferential direction of the sandwiching portion  72 . In the present embodiment, the fixing portions  73  are provided at two positions in the outer circumferential rim portion of the sandwiching portion  72 . Furthermore, the two fixing portions  73  are separated from one another by 180° in the circumferential direction of the sandwiching portion  72 . Each fixing portion  73  is provided with a fixing hole  74  that extends through the fixing portion  73 . 
     Attachment of Grommet  20  to Vehicle Body Panel  11   
     Two bolts  75  (i.e., a same number of bolts  75  as the number of fixing portions  73 ) on the vehicle body panel  11  are fixed to the surrounding portion of the insertion hole  12 . The head portions of the bolts  75  are fixed to the vehicle body panel  11  through welding or the like. The two bolts  75  are separated from one another by 180° in the circumferential direction of the insertion hole  12 . 
     When attaching the grommet  20  to the vehicle body panel  11 , first, the grommet  20  is positioned relative to the vehicle body panel  11 . The grommet  20  is positioned so that the mounting portion  21  faces the surrounding portion of the insertion hole  12  of the vehicle body panel  11  in the axial direction X 1 . At this time, the seal portion  31  comes into contact with the surrounding portion of the insertion hole  12  of the vehicle body panel  11 . Next, the bracket  71  is positioned relative to the vehicle body panel  11 . The bracket  71  is positioned relative to the vehicle body panel  11  in a manner such that the stress-absorbing portion  22  is inserted into the sandwiching portion  72  from the bottom-wall- 42  side, and the bolts  75  are inserted into the fixing holes  74 . Accordingly, the mounting portion  21  is positioned between the sandwiching portion  72  and the surrounding portion of the insertion hole  12  of the vehicle body panel  11 . 
     Then, the bracket  71  is fixed to the vehicle body panel  11  by screwing nuts  76  onto the bolts  75 . Thus, the grommet  20  is attached to the vehicle body panel  11 . When the nuts  76  are fastened, the mounting portion  21  is sandwiched between the sandwiching portion  72  and the surrounding portion of the insertion hole  12  of the vehicle body panel  11 . Furthermore, the nuts  76  are tightened until the first lip portion  32  and the second lip portion  33  come into liquid-tight close contact with the surrounding portion of the insertion hole  12  of the vehicle body panel  11 . Note that  FIG.  1    illustrates a state in which the nuts  76  have been tightened to a point immediately before the first lip portion  32  and the second lip portion  33  are pressed against the vehicle body panel  11 . 
     The operation of the present embodiment will be described. 
     Infiltration of liquids such as water from between the grommet  20  and the surrounding portion of the insertion hole  12  of the vehicle body panel  11  is suppressed by the first lip portion  32  and the second lip portion  33  that are in close contact with the surrounding portion of the insertion hole  12  of the vehicle body panel  11 . 
     If the first insertion portion  23  and the second insertion portion  24  move relative to the mounting portion  21  due to displacement or the like of the wire harnesses  13  and  14  relative to the vehicle body as illustrated in  FIGS.  1  and  3   , the stress generated by the movement of the first insertion portion  23  and the second insertion portion  24  relative to the mounting portion  21  can be absorbed by the side wall  41  due to the side wall  41  bending. In the present embodiment, the stress generated by the insertion portions  23  and  24  moving relative to the mounting portion  21  can be absorbed by the bellows portion  53  as a result of the degree of expansion of each pleat portion  56  changing, or in other words, as a result of the angle formed by a first wall portion  54  and a second wall portion  55  that are adjacent to one another changing. 
     For example, if the insertion portions  23  and  24  move relatively closer to the mounting portion  21  in the axial direction X 1 , the bellows portion  53  deforms such that the pleat portions  56  contract, or in order words, such that the angle formed by a first wall portion  54  and a second wall portion  55  that are adjacent to one another decreases. Thus, the stress generated by the insertion portions  23  and  24  moving relative to the mounting portion  21  in the axial direction X 1  can be absorbed by the bellows portion  53 . Therefore, deformation of the mounting portion  21 , which is connected to the end portion of the side wall  41  on the opposite side from the insertion portions  23  and  24 , is suppressed. Furthermore, the bellows portion  53  allows the insertion portions  23  and  24  to move relative to the mounting portion  21  in the axial direction X 1 . Note that, if the insertion portions  23  and  24  move relatively away from the mounting portion  21  in the axial direction X 1 , the stress generated by the relative movement can be absorbed by the bellows portion  53  as a result of the bellows portion  53  deforming such that the pleat portions  56  expand, or in order words, such that the angle formed by a first wall portion  54  and a second wall portion  55  that are adjacent to one another increases. 
     Furthermore, for example, if the wire harnesses  13  and  14  are inclined with respect to the axial direction X 1 , or in other words, if the insertion portions  23  and  24  are inclined with respect to the axial direction X 1 , the bellows portion  53  deforms as a result of the degree of expansion of each pleat portion  56  changing, or in order words, the bellows portion  53  deforms such that the angle formed by a first wall portion  54  and a second wall portion  55  that are adjacent to one another changes. Thus, the stress generated by the insertion portions  23  and  24  being inclined with respect to the axial direction X 1  can be absorbed by the bellows portion  53 . Thus, deformation of the mounting portion  21  is suppressed. Furthermore, the bellows portion  53  allows the insertion portions  23  and  24  to be inclined with respect to the axial direction X 1 . 
     The effects of the present embodiment will be described. 
     (1) The grommet  20  includes an annular mounting portion  21  that is to be fixed to a surrounding portion of an insertion hole  12  of a vehicle body panel  11  that includes the insertion hole  12 . In addition, the grommet  20  includes a tubular stress-absorbing portion  22  that includes a tubular side wall  41  that extends from an inner circumferential rim portion of the mounting portion  21  toward one side in an axial direction X 1 , and a bottom wall  42  that partially closes off the side wall  41  at a front end of the side wall  41 . Furthermore, the grommet  20  includes a tubular first insertion portion  23  that is provided integrally with the bottom wall  42 , and that comes into contact with an outer circumferential surface of a wire harness  13  inserted into the insertion hole  12  and covers the outer circumference of the wire harness  13 . In addition, the grommet  20  includes a tubular second insertion portion  24  that is provided integrally with the bottom wall  42 , and that comes into contact with an outer circumferential surface of a wire harness  14  inserted into the insertion hole  12  and covers the outer circumference of the wire harness  14 . The mounting portion  21  includes an annular seal portion  31  that comes into close contact with the surrounding portion of the insertion hole  12  of the vehicle body panel  11 . The side wall  41  is flexible. The first insertion portion  23  protrudes inside the stress-absorbing portion  22  from the bottom wall  42  toward the base-end side of the side wall  41 . The second insertion portion  24  protrudes inside the stress-absorbing portion  22  from the bottom wall  42  toward the base-end side of the side wall  41 . 
     According to this configuration, the insertion portions  23  and  24  are provided integrally with the bottom wall  42  of the stress-absorbing portion  22 . Furthermore, the side wall  41  of the stress-absorbing portion  22  is flexible. Thus, if the insertion portions  23  and  24  move relative to the mounting portion  21  due to an error in the arrangement position of the wire harnesses  13  and  14  with respect to the vehicle body, a difference in the lengths of the wire harnesses  13  and  14 , etc., the stress generated by relative movement can be absorbed as a result of the side wall  41  bending. In this way, the stress that is generated by the insertion portions  23  and  24  moving relative to the mounting portion  21  is absorbed by the side wall  41 , which extends from the inner circumferential rim portion of the mounting portion  21  toward one side in the axial direction X 1 . Accordingly, transmission, to the mounting portion  21 , of the stress generated by the insertion portions  23  and  24  moving relative to the mounting portion  21  can be suppressed without an increase in the size of the grommet  20  in a direction that is orthogonal to the axial direction X 1 . Furthermore, because deformation of the mounting portion  21  when the insertion portions  23  and  24  move relative to the mounting portion  21  can be suppressed, deformation of the seal portion  31  can be suppressed. Thus, a decrease in the waterproofing performance of the grommet  20  can be suppressed while suppressing an increase in the size of the grommet  20 . 
     In addition, the insertion portions  23  and  24  are provided integrally with the bottom wall  42  of the stress-absorbing portion  22 . Furthermore, the first insertion portion  23  protrudes inside the stress-absorbing portion  22  from the bottom wall  42  toward the base-end side of the side wall  41 . Similarly, the second insertion portion  24  protrudes inside the stress-absorbing portion  22  from the bottom wall  42  toward the base-end side of the side wall  41 . Thus, an increase in the size of the grommet  20  in the axial direction of the side wall  41  can be suppressed compared to a case in which the insertion portions  23  and  24  protrude in their entirety to the outside of the stress-absorbing portion  22 . Accordingly, an increase in the size of the grommet  20  in the axial direction of the side wall  41  can be suppressed even if the side wall  41  extends from the inner circumferential rim portion of the mounting portion  21  toward one side in the axial direction X 1 . 
     (2) In a cross-section of the grommet  20  taken along a plane including a center axis L 3  of the first insertion portion  23 , the first insertion portion  23  overlaps the side wall  41  in a direction that is orthogonal to the center axis L 3 . Furthermore, in a cross-section of the grommet  20  taken along a plane including a center axis L 4  of the second insertion portion  24 , the second insertion portion  24  overlaps the side wall  41  in a direction that is orthogonal to the center axis L 4 . By adopting this configuration, the insertion portions  23  and  24  protruding toward the base-end side of the side wall  41  inside the stress-absorbing portion  22  can be easily provided. 
     (3) The side wall  41  includes a plurality of pleat portions  56  that extend along a direction that intersects a center axis L 2  of the side wall  41  when seen from a direction that is orthogonal to an axial direction of the side wall. The plurality of pleat portions  56  are displaced from one another in the axial direction of the side wall  41 . 
     According to this configuration, the plurality of pleat portions  56  are displaced from one another in the axial direction of the side wall  41 . Thus, the plurality of pleat portions  56  can be provided in the stress-absorbing portion  22  while suppressing an increase in the size of the stress-absorbing portion  22  in a direction that is orthogonal to the axial direction X 1  compared to a case in which a plurality of pleat portions are arranged in the direction that is orthogonal to the axial direction X 1 . Furthermore, the stress generated by the insertion portions  23  and  24  moving relative to the mounting portion  21  can be more readily absorbed by the side wall  41  including the plurality of pleat portions  56  due to the pleat portions  56  deforming in an expanding or contracting fashion. Accordingly, because deformation of the mounting portion  21  when the insertion portions  23  and  24  move relative to the mounting portion  21  can be suppressed to a greater degree, deformation of the seal portion  31  can be suppressed to a greater degree. Thus, a decrease in the waterproofing performance of the grommet  20  can be suppressed to a greater degree. 
     (4) The pleat portions  56  each have an annular shape encircling the center axis L 2  of the side wall  41 . The plurality of pleat portions  56  are arranged from the mounting-portion- 21  side toward the bottom-wall- 42  side and form a bellows portion  53  in which adjacent ones of the pleat portions  56  are continuously connected. 
     According to this configuration, the plurality of pleat portions  56  in the side wall  41  form the bellows portion  53 . Thus, in addition to the plurality of pleat portions  56  deforming in an expanding or contracting fashion, portions between adjacent pleat portions  56  can also deform in an expanding or contracting fashion. Accordingly, the stress generated by the insertion portions  23  and  24  moving relative to the mounting portion  21  can be more readily absorbed by the side wall  41  including the bellows portion  53 . Hence, because deformation of the mounting portion  21  when the insertion portions  23  and  24  move relative to the mounting portion  21  can be suppressed to a greater degree, deformation of the seal portion  31  can be suppressed to a greater degree. Thus, a decrease in the waterproofing performance of the grommet  20  can be suppressed to a greater degree. Furthermore, because the side wall  41  allows the insertion portions  23  and  24  to move even more relative to the mounting portion  21 , a decrease in the waterproofing performance of the grommet  20  can be suppressed even more. 
     (5) The insertion portions  23  and  24  are positioned in their entirety closer to the mounting portion  21  than an outer surface  42   a  of the bottom wall  42  is in the axial direction X 1 . 
     According to this configuration, an increase in the size of the grommet  20  in the axial direction X 1  can be more readily suppressed compared to a case in which the insertion portions  23  and  24  have portions that protrude from the bottom wall  42  to the outside of the stress-absorbing portion  22 . Accordingly, an increase in the size of the grommet  20  in the axial direction X 1  can be suppressed more readily even if the side wall  41  extends from the inner circumferential rim portion of the mounting portion  21  toward one side in the axial direction X 1 . 
     (6) The outer shape of the end portion of the stress-absorbing portion  22  that is located on the bottom-wall- 42  side is smaller than the outer shape of the end portion of the stress-absorbing portion  22  that is located on an opening side of the stress-absorbing portion  22 . Thus, the size of the stress-absorbing portion  22  in a direction that is orthogonal to the center axis L 2  can be reduced near the bottom wall  42 . Moreover, the size of the grommet  20  in the direction that is orthogonal to the center axis L 2  can be reduced. Furthermore, in the present embodiment, it is easier to insert the stress-absorbing portion  22  into the sandwiching portion  72  when attaching the grommet  20  to the vehicle body panel  11 . 
     (7) The grommet  20  includes a plurality of insertion portions  23  and  24 . Generally speaking, if the grommet  20  is provided with a plurality of insertion portions  23  and  24 , the portions between the mounting portion  21  and the insertion portions  23  and  24  when seen from the axial directions of the insertion portions  23  and  24  tend to become narrower. Even in such a case, by adopting the configuration according to the present embodiment, a decrease in the waterproofing performance of the grommet  20  can be suppressed while suppressing an increase in the size of the grommet  20  in a direction that is orthogonal to the axial direction X 1 . 
     (8) The mounting portion  21  faces the surrounding portion of the insertion hole  12  of the vehicle body panel  11 , and is sandwiched between the vehicle body panel  11  and a bracket  71  that is to be fixed to the vehicle body panel  11 . In other words, the grommet  20  according to the present embodiment is mounted to the vehicle body panel  11  using the bracket  71 . In the grommet  20  characterized as such, a decrease in the waterproofing performance of the grommet  20  can be suppressed while suppressing an increase in the size of the grommet  20 . 
     The present embodiment may be modified as described below upon implementation. The present embodiment and the modifications below can be implemented in combination with one another as long as there no technical contradiction arises therebetween. 
     In the above-described embodiment, the grommet  20  is mounted to the vehicle body panel  11  using the bracket  71 . However, the grommet  20  may be mounted to the vehicle body panel  11  without using the bracket  71 . In this case, the mounting portion  21  includes an annular mounting groove that is open radially outward in the outer circumferential surface of the mounting portion  21 . Furthermore, the grommet  20  including the mounting groove is mounted to the vehicle body panel  11  by pressing the mounting portion  21  into the insertion hole  12  such that the surrounding portion of the insertion hole  12  of the vehicle body panel  11  is inserted into the mounting groove. In this grommet  20 , the bottom surface of the mounting groove corresponds to an annular seal portion that comes into close contact with the inner circumferential surface of the insertion hole  12 . 
     In the above-described embodiment, the grommet  20  includes two insertion portions, namely the first insertion portion  23  and the second insertion portion  24 . However, the number of insertion portions in the grommet  20  is not limited to this. For example, the grommet  20  may include only one insertion portion. Alternatively, for example, the grommet  20  may include three or more insertion portions. 
     The outer shape of the end portion of the stress-absorbing portion  22  that is located on the bottom-wall- 42  side may have the same size as the outer shape of the end portion of the stress-absorbing portion  22  that is located on the opening side of the stress-absorbing portion  22 . 
     In the above-described embodiment, the insertion portions  23  and  24  are positioned in their entirety closer to the mounting portion  21  than the outer surface  42   a  of the bottom wall  42  is in the axial direction X 1 . However, the position of the insertion portions  23  and  24  in the axial direction X 1  is not limited to this. It is sufficient that the first insertion portion  23  protrudes inside the stress-absorbing portion  22  from the bottom wall  42  toward the base-end side of the side wall  41 . In other words, it is sufficient that the first insertion portion  23  includes a portion that protrudes from the bottom wall  42  toward the base-end side of the side wall  41  and that is positioned inside the stress-absorbing portion  22 . In this case, the first insertion portion  23  preferably includes a portion that overlaps the side wall  41  in a direction that is orthogonal to the center axis L 3  in a cross-section taken along a plane including the center axis L 3 . Furthermore, it is sufficient that the second insertion portion  24  protrudes inside the stress-absorbing portion  22  from the bottom wall  42  toward the base-end side of the side wall  41 . In other words, it is sufficient that the second insertion portion  24  includes a portion that protrudes from the bottom wall  42  toward the base-end side of the side wall  41  and that is positioned inside the stress-absorbing portion  22 . In this case, the second insertion portion  24  preferably includes a portion that overlaps the side wall  41  in a direction that is orthogonal to the center axis L 4  in a cross-section taken along a plane including the center axis L 4 . In any case, the portion of the first insertion portion  23  to which the fixing member  61  is to be attached and the portion of the second insertion portion  24  to which the fixing member  62  is to be attached are positioned closer to the mounting portion  21  than the outer surface  42   a  of the bottom wall  42  is in the axial direction X 1 . For example, the insertion portions  23  and  24  may include portions protruding from the outer surface  42   a  of the bottom wall  42 . 
     The number of pleat portions  56  forming the bellows portion  53  is not limited to four, and it is sufficient that a plurality of pleat portions  56  form the bellows portion  53 . 
     In the above-described embodiment, the plurality of pleat portions  56  form the bellows portion  53  by adjacent ones of the pleat portions  56  being continuously connected. However, the plurality of pleat portions  56  do not necessarily need to form the bellows portion  53 . For example, pleat portions  56  that are adjacent to one another in the axial direction of the side wall  41  may be connected by a tubular portion that is a part of the side wall  41  and that extends in the axial direction X 1  but does not have the shape of a pleat. 
     As long as the side wall  41  has a tubular shape that extends from the inner circumferential rim portion of the mounting portion  21  toward one side in the axial direction X 1 , the shape of the side wall  41  is not limited to that in the above-described embodiment. For example, the side wall  41  may have a tubular shape that has a circular shape, a polygonal shape, etc., when seen from the axial direction of the side wall  41 . Also, for example, the side wall  41  may be formed from one tubular wall that does not have any bumps or dips between the mounting portion  21  and the bottom wall  42 . 
     Furthermore, for example, a stress-absorbing portion  22 A of a grommet  20 A illustrated in  FIG.  5    includes a side wall  41 A that includes a staircase portion  81  that has the shape of a staircase. Note that, in  FIG.  5   , the same reference symbols are given to configurations that are identical to or correspond to those in the above-described embodiment. The staircase portion  81  is formed so that the diameter thereof gradually decreases from the mounting-portion- 21  side toward the bottom-wall- 42  side. The staircase portion  81  includes a plurality of first wall portions  82  that have annular flat-plate-shapes and are perpendicular to the axial direction X 1 , and a plurality of second wall portions  83  that have tubular shapes and extend in parallel with the axial direction X 1 . The first wall portions  82  and the second wall portions  83  are provided alternately from the mounting-portion- 21  side toward the bottom-wall- 42  side. A step-like pleat portion  84  in which the diameter of the side wall  41 A decreases slightly is formed by a first wall portion  82  and a second wall portion  83  that are adjacent to one another in the axial direction X 1 . In the example illustrated in  FIG.  5   , the staircase portion  81  is formed by four pleat portions  84 . The pleat portions  84  each have an annular shape encircling a center axis L 21  of the side wall  41 A. 
     In the above-described embodiment, the pleat portions  56  do not necessarily need to have an annular shape encircling the center axis L 2 . It is sufficient that the pleat portions  56  extend in a direction intersecting the center axis L 2  when seen from a direction that is orthogonal to the axial direction of the side wall  41 . 
     In the above-described embodiment, the side wall  41  includes four pleat portions  56 . However, the number of pleat portions  56  in the side wall  41  is not limited to four. Furthermore, the side wall  41  does not necessarily have to include pleat portions  56 . 
     The mounting portion  21  is not limited to having a circular outer shape when seen from the axial direction X 1 . For example, the mounting portion  21  may have an annular shape whose outer shape, when seen from the axial direction X 1 , has the shape of an oval, a rounded rectangle, a keyhole, a polygon, or the like. 
     The flange portion  23   a  is not limited to having an annular shape encircling the center axis L 3 , and may have an arcuate shape extending along the circumferential direction about the center axis L 3 . The flange portion  24   a  is not limited to having an annular shape encircling the center axis L 4 , and may have an arcuate shape extending along the circumferential direction about the center axis L 4 . Furthermore, the first insertion portion  23  may not include the flange portion  23   a.  The second insertion portion  24  may not include the flange portion  24   a.    
     The insertion portions  23  and  24  are not limited to having the shape of a cylinder, and it is sufficient that the insertion portions  23  and  24  have a tubular shape. For example, the insertion portions  23  and  24  may have a tubular shape having the shape of an oval, a rounded rectangle, a polygon, or the like when seen from the axial directions of the insertion portions  23  and  24 . 
     In the above-described embodiment, the vehicle body panel  11  was mentioned as one example of an object to which the grommet  20  is to be attached. However, as long as the object to which the grommet  20  is to be attached is a member that includes an insertion hole into which a wire harness is inserted, the object is not limited to the vehicle body panel  11 . 
     As illustrated in  FIG.  3   , the grommet  20  may be formed as an integrated component. 
     The vehicle body panel  11  in the illustrated examples may be referred to as a panel surface that includes a through-hole. 
     The seal portion  31  in the illustrated examples may be referred to as an annular waterproof seal that is configured to come into waterproofing contact with the vehicle body panel  11 , and the mounting portion  21  in the illustrated example may be referred to as an annular base. 
     The stress-absorbing portion  22  in the illustrated examples, which includes the side wall  41  and the bottom wall  42 , may be referred to as a stress-absorbing dome of the grommet  20 . The first tubular portion  51  in the illustrated examples may be referred to as a dome base end of the grommet  20 . The bottom wall  42  in the illustrated examples may be referred to as a dome ceiling of the grommet  20 . The bellows portion  53  in the illustrated examples may be referred to as a bellows-shaped intermediate portion of the stress-absorbing portion  22  (stress-absorbing dome) of the grommet  20 . The staircase portion  81  in  FIG.  5    may be referred to as a step-shaped intermediate portion of the stress-absorbing portion  22  (stress-absorbing dome) of the grommet  20 . The side walls  41  and  41 A in the illustrated examples may be referred to as a radially outermost dome wall of the grommet  20 . The tubular first insertion portion  23  and the tubular second insertion portion  24  in the illustrated examples may be referred to as one or more linear sleeves or radially inner tubes that extend radially inward of the stress-absorbing portion  22  (stress-absorbing dome) of the grommet  20  along the center axis L 2  from the bottom wall  42  (dome ceiling) toward the mounting portion  21  (annular base), and that include a first opening end that is continuous with the bottom wall  42  (dome ceiling) and a second opening end (flange portion  23   a  or  24   a ) that is a free end. In the examples illustrated in  FIGS.  1 ,  3 , and  5   , the inner surface of the bottom wall  42  (dome ceiling) and the radially outer surface of each of the tubular first insertion portion  23  and the tubular second insertion portion  24  may be connected to one another so that a corner portion with a predetermined angle is formed therebetween. The axial length of the tubular first insertion portion  23  and the tubular second insertion portion  24  may be less than the protruding height of the stress-absorbing portion  22  (stress-absorbing dome) of the grommet  20 . For example, the tubular first insertion portion  23  and the tubular second insertion portion  24  may each include the free end (flange portion  23   a  or  24   a ) at a predetermined intermediate height position between the bottom wall  42  (dome ceiling) and the mounting portion  21  (annular base). The free end (flange portion  23   a  or  24   a ) of each of the tubular first insertion portion  23  and the tubular second insertion portion  24  need not be in contact with the radially inner surface of the stress-absorbing portion  22  (stress-absorbing dome) of the grommet  20 . 
     Accordingly, the grommet ( 20 ) according to one aspect of the present disclosure may include: 
     an annular base ( 21 ) that includes an annular waterproof seal ( 31 ) that is configured to come into waterproofing contact with a panel surface ( 11 ) that includes an insertion hole ( 12 ); 
     a stress-absorbing dome ( 41 ,  41 A) that protrudes by a dome height from the annular base ( 21 ), the stress-absorbing dome ( 41 ,  41 A) including a dome base end ( 51 ) that is continuous from the annular base ( 21 ), a dome ceiling ( 42 ), and a center axis (L 2 ); and 
     one or more linear sleeves ( 23 ,  24 ) that allow wire harnesses ( 13 ,  14 ) to extend through the dome ceiling ( 42 ) of the stress-absorbing dome ( 41 ,  41 A), the one or more linear sleeves ( 23 ,  24 ) extending radially inward of the stress-absorbing dome ( 41 ,  41 A) along the center axis (L 2 ) of the stress-absorbing dome ( 41 ,  41 A) from the dome ceiling ( 42 ) of the stress-absorbing dome ( 41 ,  41 A) toward the annular base ( 21 ). 
     Technical concepts that can be understood from the above-described embodiment and modifications will be described. 
     (a) In the grommet, the outer shape of the end portion of the stress-absorbing portion that is located on the bottom-wall side is smaller than the outer shape of the end portion of the stress-absorbing portion that is located on the opening side of the stress-absorbing portion. 
     According to this configuration, the size of the stress-absorbing portion in a direction that is orthogonal to the center axis of the side wall can be reduced near the bottom wall. Moreover, the size of the grommet in the direction that is orthogonal to the center axis of the side wall can be reduced. 
     (b) In the grommet, a plurality of the insertion portions are provided. 
     According to this configuration, if the grommet is provided with a plurality of insertion portions, the portions between the mounting portion and the insertion portions when seen from the axial directions of the insertion portions tend to become narrower. Even in such a case, a decrease in the waterproofing performance of the grommet can be suppressed while suppressing an increase in the size of the grommet in a direction that is orthogonal to the axial direction of the mounting portion. 
     (c) In the grommet, the mounting portion faces the surrounding portion of the insertion hole of the object to which the grommet is to be attached, and is sandwiched between the object and a bracket that is to be fixed to the object. 
     According to this configuration, in regard to a grommet that is to be attached to an object using a bracket, a decrease in the waterproofing performance of the grommet can be suppressed while suppressing an increase in the size of the grommet. 
     LIST OF REFERENCE NUMERALS 
       11  Vehicle body panel (object to which grommet is to be attached) 
       12  Insertion hole 
       13  Wire harness 
       14  Wire harness 
       20  Grommet 
       20 A Grommet 
       21  Mounting portion 
       22  Stress-absorbing portion 
       22 A Stress-absorbing portion 
       23  First insertion portion (insertion portion) 
       23   a  Flange portion 
       24  Second insertion portion (insertion portion) 
       24   a  Flange portion 
       31  Seal portion 
       32  First lip portion 
       33  Second lip portion 
       41  Side wall 
       41 A Side wall 
       42  Bottom wall 
       42   a  Outer surface 
       51  First tubular portion 
       52  Second tubular portion 
       53  Bellows portion 
       54  First wall portion 
       54   a  to  54   d  First wall portion 
       55  Second wall portion 
       55   a  to  55   d  Second wall portion 
       56  Pleat portion 
       56   a  to  56   d  Pleat portion 
       61  Fixing member 
       62  Fixing member 
       71  Bracket 
       72  Sandwiching portion 
       73  Fixing portion 
       74  Fixing hole 
       75  Bolt 
       76  Nut 
       81  Staircase portion 
       82  First wall portion 
       83  Second wall portion 
       84  Pleat portion 
     L 1  Center axis (center axis of mounting portion) 
     L 2  Center axis (center axis of side wall) 
     L 3  Center axis (center axis of insertion portion) 
     L 4  Center axis (center axis of insertion portion) 
     L 21  Center axis (center axis of side wall) 
     X 1  Axial direction