JP2017111873A - Wiring harness - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring harness capable of exhibiting reliable whirl stop action when fastening a connection terminal, without providing any special whirl stop shape on the fixing object side of the connection terminal.SOLUTION: In a wiring harness where a connection terminal 13 is fastened to the car body side earth member 15 by means of a fastening bolt 17, the connection terminal 13 includes an annular plate terminal 32 having a wire coupling part 31, and a compression surface 32a onto which a screw fastening force from the fastening bolt 17 is applied, and a connection surface 32b coming into pressure contact with the car body side earth member 15, and a through hole 32c penetrating at least the male screw side member out of the fastening bolt 17 and car body side earth member 15, and a whirl stop claw 33 supported integrally with any one of the plate terminal 32 and wire coupling part 31, coming into local pressure contact with the car body side earth member 15, when the screw fastening force is applied from the fastening bolt 17 to the plate terminal 32, and performing whirl stop of the plate terminal 32 and wire coupling part 31 for the car body side earth member 15.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wire harness, and more particularly to a wire harness having a terminal detent structure suitable for fastening a connection terminal to an object to be connected by fastening means such as an electric tool.

  In a production line of an automobile or the like that mounts a wire harness, when fixing a connection terminal attached to an electric wire of the wire harness to a connection object that is an object of electrical connection, screw fastening, particularly bolt fastening, with an electric tool or the like There are many.

  In such a case, the bolt (or nut) that is driven to rotate with a required tightening torque by an electric tool or the like rotates in the screw tightening direction while contacting the connection terminal, so that the bolt and the connection terminal are rotated around the rotation center. Easy to do. Therefore, in order to prevent unreasonable force from acting on the wire due to the connection terminal being rotated when the bolt is tightened, a rotation prevention structure that can prevent the connection terminal from rotating with the bolt has been proposed. Has been.

  As a wire harness having this type of terminal detent structure, for example, a concave / convex engagement between a connection terminal that does not have a detent shape and a bolt head so that it can be detented against the panel around the fastening portion of the connection terminal In addition, there is known one in which an anti-rotation metal fitting that multi-guides the outer periphery of the connection terminal is interposed (for example, see Patent Document 1).

JP 2002-50417 A

  However, in the conventional wire harness as described above, in addition to the need for a component for preventing rotation separately from the connection terminal, a through hole for preventing rotation is provided on the side of the connection object such as the vehicle body panel. Since it was necessary to form the unevenness which forms or a level | step difference surface, the manufacturing cost required for wiring of a wire harness was high.

  In addition, in order to provide such a detent shape on the connection object side, there are restrictions on the fixing position of the connection terminal and the layout of the wire harness, or it is not possible to provide a detent shape on the connection object side. In order to perform the detent work together with the fastening work, it takes time to fix the connection terminal.

  The present invention has been made in order to solve such a conventional problem, and is reliable when the connection terminal is fixed by the screw fastening member without providing a special detent shape on the fixed object side of the connection terminal. An object of the present invention is to provide a wire harness that can exert a detent action.

  In order to achieve the above object, a wire harness according to the present invention includes an electric wire and a connection terminal coupled to the electric wire, and the connection terminal is screwed to a mating member for electrical connection by a fastening member. A wire harness that is fastened to a member, wherein the connection terminal has a wire coupling portion that is coupled to the electric wire, a pressure surface to which a screw fastening force from the fastening member is applied, and a connection surface that is in pressure contact with the mating member. And an annular plate terminal portion having a through hole for penetrating at least the male screw side member of the fastening member and the counterpart member, and is integrally supported by any of the plate terminal portion and the wire coupling portion, When the screw fastening force is applied from the fastening member to the plate terminal portion, the plate terminal portion and the wire coupling portion are locally pressed against the mating member of the electrical connection. Characterized in that it has a, a local pressure contact portion for detent to the mating member of the electrical connection.

  With this configuration, when a screw fastening force is applied from the fastening member to the plate terminal portion of the connection terminal, the local pressure contact portion of the connection terminal is locally pressed against the mating member of the electrical connection, and the plate terminal portion and the electric wire coupling The part exerts a locking force or a gripping force due to a spike effect or the like with respect to the counterpart member. Therefore, the rotational resistance force of the connection terminal against the mating member is sufficiently increased against the frictional force applied in the rotational direction from the fastening member to the plate terminal portion of the connection terminal, and the connection terminal can be prevented from rotating.

  In the wire harness of the present invention, the local pressure contact portion is in a specific region on the outer peripheral side of the connection surface of the plate terminal portion and in a specific seat surface region separated from the center of the through hole by an outer peripheral radius or more. The projection is projected in a direction from the pressure surface to the connection surface in at least one of the regions, and is crushed by the screw fastening force applied from the fastening member to the plate terminal portion. May be.

  In addition, when the screw fastening force is applied from the fastening member to the plate terminal portion on the pressure surface of the plate terminal portion adjacent to the through hole, the material on the pressure surface side of the connection terminal with respect to the fastening member An annular sliding contact portion that slides in contact with the fastening member with a friction coefficient smaller than that of the surface may be provided.

  ADVANTAGE OF THE INVENTION According to this invention, the wire harness which can exhibit a reliable anti-rotation effect at the time of fixation of the connection terminal by a screw fastening member can be provided, without providing a special anti-rotation shape in the fixed object side of a connection terminal.

It is a side view near the connecting terminal of the wire harness according to the first embodiment of the present invention. (A) is a top view of the principal part of the connection terminal in the wire harness which concerns on the 1st Embodiment of this invention, (b) is a bottom view of the principal part. It is explanatory drawing of the local press-contact part in the connection terminal of the wire harness which concerns on the 2nd Embodiment of this invention. It is a side view near the connection terminal of the wire harness which concerns on the 3rd Embodiment of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(First embodiment)
1 and 2 show a first embodiment of a wire harness according to the present invention. In addition, although this Embodiment applies this invention to the wire harness which has a connection terminal for earth connection mounted in a motor vehicle, this invention is applicable also when it has a connection terminal other than for earth connection. Of course, it can be applied. In addition, here, the main part of the connection terminal is exemplified as a circular plate terminal portion, but it can also be applied to a polygonal or other non-circular plate terminal portion.

  As shown in FIG. 1, the wire harness 10 according to the present embodiment includes a wire harness body 11 mainly composed of an insulation-coated electric wire 12 and a round plate terminal that is crimp-connected to one end of the electric wire 12. It is comprised including the connection terminal 13 which is.

  Although the wire harness main body 11 may be comprised including the some electric wire which is not illustrated other than the electric wire 12, only the electric wire 12 is shown in the figure.

  The electric wire 12 is a covered electric wire having, for example, a core wire portion 21 made of a conductor wire such as an annealed copper wire or an aluminum electric wire, and a covering material 22 that insulates the core wire portion 21 over almost the entire length direction. The electric wire 12 is connected to, for example, a vehicle auxiliary machine (a part of the vehicle electrical component) outside the figure on the other end side opposite to the one end side to which the connection terminal 13 is crimped.

  The connection terminal 13 is fastened by a fastening bolt 17 (screw fastening member) to a vehicle body side ground member 15 which is a counterpart member for electrical connection.

  The connection terminal 13 includes an electric wire coupling portion 31 coupled to the core wire portion 21 of the electric wire 12 and a plate terminal portion 32 formed integrally with the electric wire coupling portion 31. Further, in the vicinity of the outer peripheral edge of the plate terminal portion 32, a plurality of detent locking claw portions 33 (local pressure contact portions) that exhibit a function of preventing the plate terminal portion 32 from rotating with respect to the vehicle body side ground member 15 are attached. .

  As shown in FIG. 1, FIG. 2 (a) and FIG. 2 (b), for example, the wire coupling portion 31 is crimped or exposed to the exposed end portion 21a of the core wire portion 21 exposed by stripping the end portion of the electric wire 12. It is a welded wire barrel part and is firmly coupled to the core part 21 of the electric wire 12. Of course, in addition to the wire barrel portion, the wire coupling portion 31 may be provided with a resin barrel portion that holds the end portion of the covering material 22 of the wire 12 together with the core wire portion 21.

  The plate terminal portion 32 is a component that is pressed using a metal plate such as an oxygen-free copper plate having good conductivity. When the fastening bolt 17 is screwed, the plate terminal portion 32 has a downward pressing force (screw fastening force) and circumferential friction in FIG. A pressing surface 32a to which a force is applied and a connection surface 32b that presses against the vehicle body side ground member 15 with a contact pressure corresponding to a screw fastening force from the pressing surface 32a.

  The vehicle body-side ground member 15 is a member that forms a portion serving as a ground point in the vehicle body of an automobile. Although shown in FIG. 1 as a thick plate, a thinner vehicle body panel or any shape supported by it A conductive member or the like may be used.

  Further, the plate terminal portion 32 has a through hole 32c through which the screw shaft portion 17b of the fastening bolt 17 (a member on the male screw side at least among the mating members) passes. In addition, when the vehicle body side grounding member 15 has a male thread part and the nut replaced with the fastening bolt 17 is employ | adopted, the male thread part of the vehicle body side grounding member 15 will penetrate the through-hole 32c.

  Further, the locking stopper claw portion 33 is locally provided on the seating surface region 13 b of the connection terminal 13 facing the terminal connection side surface 15 a of the vehicle body side ground member 15, and is connected to the plate terminal portion 32 from the fastening bolt 17. When a screw fastening force is applied, it is locally pressed against the vehicle body side ground member 15 to be a local pressure contact portion that prevents the wire coupling portion 31 and the plate terminal portion 32 from rotating with respect to the vehicle body side ground member 15.

  More specifically, each rotation-stopping claw portion 33 is formed in the specific region Ra on the outer peripheral side of the connection surface 32b of the plate terminal portion 32 that is a predetermined radius r1 or more from the center of the through hole 32c and the center of the through hole 32c. The protrusion 33a protrudes in the plate thickness direction from the pressure surface 32a toward the connection surface 32b in at least one of the specific seating surface regions Rb separated from the outer peripheral radius r2 of the connection surface 32b. The predetermined radius r1 is larger than the radius r0 of the through hole 32c and smaller than the outer peripheral radius r2 of the connection surface 32b.

  Further, the protrusions 33a of the respective locking stopper claws 33 have, for example, the above-described protruding heights in the plate thickness direction in the radially outer side and the one circumferential side of the plate terminal portion 32 (in FIG. 2B). It has a substantially triangular pyramid shape that becomes higher as it goes counterclockwise. When a screw fastening force is applied to the plate terminal portion 32 from the fastening bolt 17, the projection 33 a is in pressure contact with the vehicle body side ground member 15 locally, and together with the fastening bolt 17, the plate terminal portion. It functions as a locking claw for restricting the rotation to one side in the circumferential direction. In addition, each protrusion 33a shown in FIG. 1 has a cut-and-raised shape with an adjacent concave portion 33b like a grater shape, but is welded to the connection terminal 13 or protruded. It may be.

  Furthermore, the wire coupling portion 31, the plate terminal portion 32, and the locking stopper claw portion 33 of the connection terminal 13 are subjected to a vehicle body side ground member 15 when a screw fastening force of a predetermined value or more is applied from the fastening bolt 17 to the plate terminal portion 32. The protrusion 33a that is locally press-contacted with respect to is crushed from the tip side. As a result, when a screw fastening force of a predetermined value or more is applied from the fastening bolt 17 to the plate terminal portion 32, a sufficient contact surface pressure that is stable over substantially the entire connection surface 32b of the plate terminal portion 32 until the screw fastening is completed. It has come to be obtained.

  On the other hand, on the pressure surface 32a adjacent to the through hole 32c of the plate terminal portion 32, when a screw fastening force is applied from the fastening bolt 17 to the plate terminal portion 32, the connection terminal 13 is applied to the head portion 17a of the fastening bolt 17. An annular sliding contact portion 35 that slides in contact with the head 17a of the fastening bolt 17 with a friction coefficient smaller than that of the material surface 13a on the pressure surface 32a side is provided.

  For example, the sliding contact portion 35 is coated with a friction coefficient stabilizer in an annular thin plate shape in the inner peripheral region Rc that is less than the predetermined radius r1 from the center of the through hole 32c in the pressing surface 32a of the plate terminal portion 32. It is a dry film.

  The coefficient of friction stabilizer that forms the sliding contact portion 35 is known as an emulsion state in which, for example, a wax-like friction reducing material, a surfactant, a water-miscible synthetic resin for film formation, or the like is dissolved in an aqueous solvent. (See, for example, “Made Co., Ltd., trade name“ Neo Tolker ”, JP-A-6-80983). Of course, the sliding contact portion 35 may be formed of another resin film or a dry lubricating film that has a low friction coefficient with respect to the fastening bolt 17.

  In the wire harness 10 of the present embodiment, the friction in the tightening direction of the fastening bolt 17 is thus reduced on the pressure surface 32a side of the plate terminal portion 32 of the connection terminal 13, and for example, against the fastening bolt 17 that is electrogalvanized. The coefficient of friction is about 0.09. On the other hand, on the connection surface 32b side of the plate terminal portion 32, for example, a friction coefficient of 0.35 or more with respect to the vehicle body panel or the like due to a spike effect or the like at the time of the pressure contact of the protrusion 33a of the rotation stop claw portion 33 to the vehicle body side ground member 15 A large rotational resistance force corresponding to the frictional resistance with a sufficiently high friction coefficient is generated to prevent the connection terminal 13 from rotating.

  Next, the operation will be described.

  In the wire harness 10 of the present embodiment configured as described above, when a screw fastening force is applied from the fastening bolt 17 to the plate terminal portion 32 of the connection terminal 13, the rotation locking claw portion 33 of the connection terminal 13 is The wire-bonding portion 31 and the plate terminal portion 32 exert a locking force due to a spike effect or the like on the vehicle body-side ground member 15 by locally pressing against the vehicle-body-side ground member 15.

  Therefore, the rotational resistance force of the connection terminal 13 to the vehicle body side ground member 15 is sufficiently increased against the low frictional force in the tightening rotation direction applied from the fastening bolt 17 to the plate terminal portion 32 of the connection terminal 13. It can be stopped.

  Further, in the present embodiment, the locking stopper claw portion 33 is separated from the inside of the specific region Ra on the outer peripheral side of the connection surface 32b of the plate terminal portion 32 and the outer periphery radius r2 of the connection surface 32b from the center of the through hole 32c. Within at least one of the specific seating surface regions Rb, a plurality of projections 33a projecting in the direction of the plate thickness t from the pressure surface 32a toward the connection surface 32b are formed. By the screw fastening force applied to the terminal part 32, it is crushed on the outer peripheral side of the connection surface 32b.

  Therefore, a stable and sufficient contact surface pressure with respect to the vehicle body-side ground member 15 is obtained over substantially the entire area of the connection surface 32b of the plate terminal portion 32, and reliable electrical connection performance is ensured.

  Furthermore, in the present embodiment, since the annular sliding contact portion 35 is provided on the pressure surface 32 a of the plate terminal portion 32, the rotation resistance of the plate terminal portion 32 against the vehicle body side ground member 15 by the detent locking claw portion 33. In combination with increasing the length of the connection terminal 13, the connection terminal 13 is reliably prevented from rotating with respect to the fastening bolt 17 when the connection terminal 13 is fastened.

  As a result, in the present embodiment, it is necessary to provide the vehicle body side ground member 15 with a rotation prevention shape such as a punch hole or a butting portion, or to provide the connection terminal 13 with a bending portion that engages with the rotation prevention shape portion. In addition, since it is not necessary to increase the types of connection terminals 13, the number of parts and the number of processing steps can be reduced. Further, since the punching hole or the like is not required for the vehicle body side ground member 15, the machining cost can be reduced. Furthermore, since the anti-rotation shape is provided on the vehicle body side, the installation posture of the connection terminal 13 and the layout of the wire harness 10 are not limited, and it is difficult to provide the anti-rotation shape. The problem of taking time and effort is also eliminated.

As described above, in the present embodiment, the connection terminal 13 is fastened and fixed to the vehicle body side ground member 15 without providing a special anti-rotation shape to the vehicle body side ground member 15 that is the object to be fixed to the connection terminal 13. Thus, it is possible to provide the wire harness 10 capable of exhibiting the 13 reliable detent action.
(Second Embodiment)
FIG. 3 shows a wire harness according to the second embodiment of the present invention.

  Each embodiment described below is different from the first embodiment described above in the form of the local pressure contact portion attached to the plate terminal portion 32 of the connection terminal 13, but the other configurations are the first. This is similar to the first embodiment. Therefore, hereinafter, the same or similar configurations as those of the first embodiment are referred to by using the reference numerals of corresponding components in the first embodiment shown in FIG. 1 and FIG. Differences between this embodiment and the first embodiment will be described.

  As shown in FIG. 3, in the wire harness 10 of the present embodiment, a plurality of slips spaced apart in the circumferential direction are used instead of the anti-rotation locking claw portion 33 and the annular slide contact portion 35 in the first embodiment. A stop portion 43 (local pressure contact portion) and a sliding contact portion 45 are provided.

  The plurality of non-slip portions 43 have, for example, a plurality of serrated projections 43 a in a substantially half-circumferential section on the distal end side of the plate terminal portion 32 that is separated from the wire coupling portion 31, and the plate terminal portion 32 extends from the fastening bolt 17. When a screw fastening force is applied to the vehicle body side ground member 15, the plurality of protrusions 43 a are locally pressed against the vehicle body side ground member 15 so as to prevent the wire coupling portion 31 and the plate terminal portion 32 from rotating with respect to the vehicle body side ground member 15. It has become.

  More specifically, the plurality of protrusions 43a of each rotation preventing portion 43 are pressed surfaces within a specific region Ra on the outer peripheral side of the connection surface 32b of the plate terminal portion 32 that is a predetermined radius r1 or more from the center of the through hole 32c. It projects in the plate thickness direction from 32a toward the connection surface 32b.

  Further, the protrusions 43a of the respective rotation stoppers 43 become higher as, for example, the protrusion height in the plate thickness direction described above becomes closer to one side in the circumferential direction of the plate terminal portion 32, and the predetermined height from the fastening bolt 17 to the plate terminal portion 32 is increased. When a screw fastening force greater than the value is applied, the projection 43a that is locally pressed against the vehicle body side ground member 15 is set to have a radial width and a projection height that are crushed from the tip side. As a result, when a screw fastening force of a predetermined value or more is applied from the fastening bolt 17 to the plate terminal portion 32, a sufficient contact surface pressure that is stable over substantially the entire connection surface 32b of the plate terminal portion 32 until the screw fastening is completed. It has come to be obtained.

  On the other hand, the sliding contact portion 45 is formed in the inner peripheral region Rc of the pressing surface 32a of the plate terminal portion 32 that is less than the predetermined radius r1 from the center of the through hole 32c. Contrary to 43 a, for example, the protrusion height in the plate thickness direction described above increases as it goes to the other side in the circumferential direction of the plate terminal portion 32.

  The sliding contact portion 45 is coated with the above-described coefficient of friction stabilizer or a lubricant film, and when a screw fastening force is applied from the fastening bolt 17 to the plate terminal portion 32, the sliding contact portion 45 becomes the head of the fastening bolt 17. The sliding contact with the head 17a of the fastening bolt 17 is made with a friction coefficient smaller than that of the material surface 13a on the pressing surface 32a side of the connection terminal 13 with respect to the portion 17a.

Also in the present embodiment, a reliable detent action of the connection terminal 13 can be exhibited when the connection terminal 13 is fastened and fixed, without providing a special detent shape to the vehicle body side ground member 15 that is the fixing object of the connection terminal 13. The wire harness 10 can be provided.
(Third embodiment)
FIG. 4 shows a wire harness according to the third embodiment of the present invention.

  As shown in FIG. 4, in the wire harness 10 of the present embodiment, the connection surface 32 b is formed from the center of the through hole 32 c of the plate terminal portion 32 in place of the anti-rotation locking claw portion 33 in the first embodiment. An elastic non-slip portion 53 (local pressure contact portion) located in the specific seating surface region Rb separated by an outer radius r2 or more is provided. Moreover, the connection terminal 13 has the level | step-difference part 33 of the plate | board thickness direction in the connection end part side of the plate terminal part 32 with respect to the electric wire coupling part 31 among the specific seat surface area | regions 13b.

  The elastic slip preventing portion 53 in the present embodiment is disposed, for example, immediately below the wire coupling portion 31 in FIG. 4, and has a plurality of quadrangular pyramid-shaped protrusions on the lower surface side in FIG. 53a. These protrusions 53a are the same as a large number of quadrangular pyramid-shaped protrusions formed by, for example, so-called cross-cutting on a metal surface.

  Further, the elastic anti-slip portion 53 is formed in a plate shape from an elastic synthetic resin such as rubber, rubber, or the like, and the plurality of protrusions 53a are lower than the connection surface 32b of the plate terminal portion 32 in FIG. It protrudes slightly to the side.

  The elastic non-slip portion 53 has the plurality of protrusions 53a in the specific seating surface region Rb that is separated from the center of the through hole 32c by the outer peripheral radius r2 of the connection surface 32b. When a screw fastening force is applied, the plurality of protrusions 53a are locally pressed against multiple points on the vehicle body side ground member 15 to prevent the wire coupling portion 31 and the plate terminal portion 32 from rotating relative to the vehicle body side ground member 15. The required grip can be demonstrated.

  In addition, although the range which can install the elastic slip prevention part 53 is in the specific seat surface area | region Rb of the connection terminal 13, as shown in FIG. 4, the electric wire coupling | bond part 31 of the connection terminal 13 from the vehicle body side ground member 15 is shown. Needless to say, the installation range is limited to a range in which the elastic slip preventing portion 53 can be pressed against the vehicle body side ground member 15. Further, the plurality of protrusions 53a may be different in hardness from the plate-like portion 53b of the elastic slip-preventing portion 53, and may be formed of particles or fibers partially embedded in the plate-like portion 53b.

  Also in the present embodiment, a reliable detent action of the connection terminal 13 can be exhibited when the connection terminal 13 is fastened and fixed without providing a special detent shape to the vehicle body side grounding member 15 that is an object to be fixed to the connection terminal 13. The wire harness 10 can be provided.

  In each of the above-described embodiments, the connection terminal 13 is a terminal for ground connection, but it goes without saying that the connection application may be different.

  As described above, the present invention can provide a wire harness that can reliably prevent rotation when a connection terminal is fixed by a screw fastening member without providing a special rotation prevention shape on the fixed object side of the connection terminal. It is useful for all wire harnesses having a terminal detent structure suitable for fastening a connection terminal to a connection object by fastening means such as an electric tool.

10 Wire harness 12 Electric wire (Coated wire)
13 Connection terminal 13a Material surface 13b Seat surface area 15 Car body side ground member (mating side member for electrical connection, connection object)
17 Fastening bolt (fastening member, male screw side member)
17a head 21 core wire portion 21a exposed end portion 31 electric wire coupling portion 32 plate terminal portion 32a pressure surface 32b connection surface 32c through hole 33 detent locking claw portion (polar contact portion)
33a, 43a, 53a Protrusion (plural protrusions)
35, 45 Sliding contact part 43 Non-slip part (extreme pressure contact part)
53 Elastic non-slip part (Polar pressure contact part)
r1 predetermined radius r2 outer radius Ra specific area Rb specific bearing surface area Rc inner peripheral area

Claims (3)

An electrical wire and a connection terminal coupled to the electrical wire, wherein the connection terminal is a wire harness that is fastened to the counterpart member by a fastening member that is screwed to the counterpart member of electrical connection,
The connection terminal is
A wire coupling portion coupled to the wire;
An annular shape having a pressurizing surface to which a screw fastening force from the fastening member is applied and a connection surface that is in pressure contact with the counterpart member, and having a through hole through which at least the male screw side member passes through the fastening member and the counterpart member. A plate terminal,
When the screw fastening force is applied from the fastening member to the plate terminal portion, the plate terminal portion and the wire coupling portion are integrally supported, and locally pressed against the mating member of the electrical connection. And a local pressure contact portion that prevents the plate terminal portion and the wire coupling portion from rotating with respect to the mating member of the electrical connection.   The local pressure contact portion is in a specific region on the outer peripheral side of the connection surface of the plate terminal portion and in a specific seating surface region separated from the center of the through hole by an outer peripheral radius of the connection surface or more. 2, and is formed by a protrusion protruding in a direction from the pressure surface toward the connection surface, and is crushed by the screw fastening force applied to the plate terminal portion from the fastening member. Wire harness.   When the screw fastening force is applied from the fastening member to the plate terminal portion on the pressure surface of the plate terminal portion adjacent to the through hole, the material surface on the pressure surface side of the connection terminal with respect to the fastening member The wire harness according to claim 1 or 2, further comprising an annular sliding contact portion that makes sliding contact with the fastening member with a friction coefficient smaller than a friction coefficient.

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