JP2017072215A - nut - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nut capable of being properly fastened, and enabling a user to easily confirm that fastening has been properly done.SOLUTION: A nut is configured such that on an outer peripheral surface of an outside member 5; an opening part 55 opening in a radial direction is formed, in an inside member 2, a projection part 30 arranged at the opening part 55 is provided; when torque in a fastening direction less than a predetermined amount is added to the outside member 5, the inside member 2 and the outside member 5 rotate in an integrated manner, and the torque is transmitted from the outside member 5 to the inside member 2; and when torque in the fastening direction equal to or larger than the predetermined amount is added to the outside member 5, the inside member 2 does not rotate but the outside member 5 rotates, and the projection part 30 is arranged at a predetermined position of the opening part 55.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a nut.

  Conventionally, a sink such as a kitchen or a bathroom and a pipe such as a trap are connected using a nut. As such a piping nut, an internal screw member provided with a female screw fastened to a male screw provided on the sink side, and an internal screw member accommodated in the interior and rotational torque in the fastening direction to the internal screw member An outer shell member that conveys, a protrusion is provided on the outer side of the inner screw member, a plurality of protrusions are provided on the inner side of the outer shell member, and a ratchet portion that engages with the protrusion of the inner screw member is provided Has been proposed (see Patent Document 1 below). In this piping nut, when a rotational torque less than the reference in the fastening direction is applied to the outer shell member, the projecting piece and the ratchet portion mesh with each other, and the rotational torque is transmitted to the inner screw member, resulting in a rotational torque exceeding the reference. Is added, the engagement between the projecting piece and the ratchet portion is eliminated, and the outer shell member is configured to idle with respect to the inner screw member.

Japanese Patent No. 4756204

  However, in the piping nut described in the above-mentioned Patent Document 1, a user such as a contractor senses the idling of the outer shell member as to whether the inner screw member is properly fastened to the male screw of the sink. It can only be recognized and difficult to confirm. Furthermore, when inspecting whether it is fastened, there exists a problem that it cannot confirm visually. In particular, in the nut that connects the sink and trap of the kitchen, if the inner screw member is not fastened properly, there is a possibility of water leaking from the location, so it is easy for the user to confirm the fastening of the inner screw member Is desired.

  Therefore, the present invention has been made in view of the above circumstances, and provides a nut that can be properly tightened and visually confirmed that it has been properly tightened.

In order to achieve the above object, the present invention employs the following means.
That is, the nut according to the present invention is rotatable with respect to the inner member on the outer side in the radial direction of the inner member and the inner member having a female screw portion fastened to the male screw portion provided on the fastening object. An outer member attached to the outer member, and an outer circumferential surface of the outer member is formed with an opening that penetrates in the radial direction, and the inner member is disposed in the opening. The inner member and the outer member rotate as a unit when the outer member is applied with a torque in a fastening direction less than a predetermined amount, and the outer member is rotated from the outer member to the inner member. When torque is transmitted and a torque in the fastening direction that is greater than or equal to the predetermined amount is applied to the outer member, the inner member does not rotate but the outer member rotates, and the protrusion portion is a predetermined portion of the opening. It is arranged at the position of

  In the nut configured as described above, when a torque in a fastening direction less than a predetermined amount is applied to the outer member, the inner member and the outer member rotate as a unit, and torque is transmitted from the outer member to the inner member. Is done. Thereby, the internal thread part of an inner side member is fastened by the external thread part provided in the fastening target object. When the torque in the fastening direction of a predetermined amount or more is applied to the outer member, the inner member does not rotate but the outer member rotates. Therefore, the nut can be properly fastened to the fastening object with a predetermined amount of torque in the fastening direction. Further, at this time, since the protrusion of the inner member is disposed at a predetermined position of the opening formed on the outer peripheral surface of the outer member, the user visually confirms that the protrusion is disposed at the predetermined position. By confirming with, it can be grasped that the nut has been properly fastened to the fastening object.

  Moreover, it is preferable that the nut which concerns on this invention is provided with the marking part corresponding to the said predetermined position where the said projection part is arrange | positioned in the said opening part in the outer peripheral surface of the said outer member.

  In the nut configured as described above, the outer peripheral surface of the outer member is provided with a mark portion corresponding to a predetermined position where the protrusion is disposed in the opening. Therefore, if the nut is properly fastened to the fastening object, the protruding portion is arranged at a position corresponding to the mark portion, and thus the user can easily confirm that the fastening has been properly made.

  In the nut according to the present invention, when a torque in the fastening direction is applied to the outer member in a state where the protrusion is disposed at the predetermined position of the opening, the protrusion is The configuration may be such that the torque is transmitted from the outer member to the inner member by engaging with the rear end of the fastening direction.

  In the nut configured as described above, when a torque in the fastening direction is applied to the outer member in a state where the protrusion is disposed at a predetermined position of the opening, the protrusion is a rear end portion of the opening in the fastening direction. The torque is transmitted from the outer member to the inner member. Therefore, after the nut is properly fastened to the fastening object, the nut can be further tightened.

  According to the nut according to the present invention, it can be properly fastened and can be visually confirmed that it has been fastened properly.

It is a side view of the tank body of the kitchen with which the nut concerning one embodiment of the present invention was fastened. It is the disassembled perspective view which removed the nut which concerns on one Embodiment of this invention from the tank body of the kitchen, and was seen from upper direction. It is the disassembled perspective view which removed the nut which concerns on one Embodiment of this invention from the tank of the kitchen, and was seen from the downward direction. In one embodiment of the present invention, the right side of the nut in a state where torque in the fastening direction is not applied to the outer member is a plan view, and the left side is a horizontal sectional view. In one Embodiment of this invention, it is a side view of the nut in the state where the torque to a fastening direction is not applied to the outer side member. In the nut which concerns on one Embodiment of this invention, it is a figure which shows the locus | trajectory of the downward protrusion part at the time of fastening. In one embodiment of the present invention, the right side of the nut in a state where torque in the fastening direction is applied to the outer member is a plan view, and the left side is a horizontal sectional view. The right side of the nut in a state where the outer member is further rotated in the fastening direction than FIG. 7 is a plan view, and the left side is a horizontal sectional view. In one Embodiment of this invention, it is a side view of the nut of the state in which the torque to the fastening direction was applied to the outer side member. In the nut which concerns on one Embodiment of this invention, it is a figure which shows the locus | trajectory of the downward protrusion part at the time of loosening. In one embodiment of the present invention, the right side of the nut in the middle of relaxation is a plan view and the left side is a horizontal sectional view.

Hereinafter, as a nut according to an embodiment of the present invention, a nut used for a tank body such as a sink of a kitchen will be described as an example.
FIG. 1 is a side view of a kitchen tank body to which a nut according to an embodiment of the present invention is fastened. FIG. 2 is an exploded perspective view of the nut according to the embodiment of the present invention, which is removed from the kitchen tank and viewed from above. FIG. 3 is an exploded perspective view of the nut according to the embodiment of the present invention, which is removed from the kitchen tank and viewed from below.
As shown in FIGS. 1 to 3, the tank body 100 is connected to a trap 110 by a nut 1.

  As shown in FIG. 2, a connecting body (fastening object) 102 extending downward in a cylindrical shape is fixed to the bottom 100 </ b> B of the tank body 100 provided on the top plate 101 (see FIG. 1) of the kitchen. A male screw portion 102 </ b> X is provided on the outer peripheral surface of the lower portion of the coupling body 102.

  As shown in FIGS. 2 and 3, the nut 1 includes an inner member 2 that is fastened to the coupling body 102 of the tank body 100 and forms an annular shape, and an outer member 5 that is mounted on the radially outer side of the inner member 2. I have. In the present embodiment, the inner member 2 and the outer member 5 are made of resin. Hereinafter, the nut 1 is demonstrated as what is arrange | positioned along the axis line O direction which makes an up-down direction.

  The inner member 2 includes an inner ring body 20 formed in an annular shape, an engagement claw portion (protrusion section) 30 projecting radially outward from the outer peripheral surface 20P of the inner ring body 20, and an upper surface 20T of the inner ring body 20. And an upward convex portion 40 protruding upward.

  On the inner peripheral surface of the inner annular body 20, a female screw portion 20X that is fastened to the male screw portion 102X of the coupling body 102 of the tank body 100 is formed. On the inner peripheral surface of the inner annular body 20, a packing 21 made of a soft resin is fitted on the upper part.

  A lower fitting portion 22 that is recessed in an annular shape upward is formed in the lower portion of the inner annular body 20. The upper end portion of the trap 110 is fitted into the lower fitting portion 22.

  The engaging claw 30 has a height that is substantially the same as the vertical height of the inner annular body 20. The engaging claw portions 30 are provided at four locations at substantially equal intervals in the circumferential direction of the inner annular body 20.

FIG. 4 is a plan view on the right side and a horizontal cross-sectional view on the left side of the nut 1 in a state where the torque in the fastening direction X is not applied to the outer member 5. FIG. 5 is a side view of the nut 1 in a state where no torque in the fastening direction X is applied to the outer member 5. FIG. 6 is a diagram illustrating a locus of the downward projecting portion 70 when the nut 1 is fastened.
In addition, the direction rotated when the nut 1 is tightened is referred to as a fastening direction X, and the direction rotated when the nut 1 is loosened is referred to as a relaxation direction Y. The fastening direction X and the relaxation direction Y are also referred to as circumferential directions.
As shown in FIGS. 4 and 6, each upward convex portion 40 is formed continuously on the inner support surface 41 formed rearward in the fastening direction X and the radially outer end of the inner support surface 41. And an outer side surface 42. Further, the upward convex portion 40 is continuous with the inner engagement surface 43 formed continuously at the front end portion in the fastening direction X of the outer surface 42 and the radially inner end portion of the inner engagement surface 43. And an inner sliding surface 44 formed in this manner.

  The inner support surface 41 is formed to be inclined with respect to the radial direction so as to go to the outer side in the radial direction and therefore gradually toward the front in the fastening direction X. The outer side surface 42 is formed along the circumferential direction. The inner engagement surface 43 is formed along the radial direction. In the inner sliding surface 44, the front side in the fastening direction X is formed to be slightly inclined with respect to the circumferential direction so as to gradually go inward in the radial direction toward the rear of the fastening direction X. The rear side of the fastening direction X in the inner sliding surface 44 is formed along the circumferential direction.

  A corner 41C formed by the inner support surface 41 and the outer surface 42, a corner 42C formed by the outer surface 42 and the inner engagement surface 43, and an inner engagement surface 43 and an inner sliding surface 44 are formed. The corners 43C and the corners 44C formed by the inner sliding surface 44 and the inner support surface 41 are each formed in a curved shape.

  As shown in FIGS. 2 and 3, the outer member 5 is formed in an annular shape, and is formed on an outer annular body 50 disposed on the outer side in the radial direction of the inner member 2, and is formed on a lower end of the outer annular body 50. And a flange 51 extending outward.

  A concave portion 52 that is recessed inward in the radial direction is formed on the outer peripheral surface of the outer annular body 50. The recess 52 is formed in an arc shape in plan view. By forming a plurality of concave portions 52 in the circumferential direction, a convex portion 53 that swells radially outward is formed between the concave portions 52. Since the concave portion 52 and the convex portion 53 are continuously arranged, the structure is configured to prevent slipping when the user grips and fastens the outer member 5.

  As shown in FIGS. 3 and 5, an opening 55 that penetrates in the radial direction is formed in the lower portion of the outer annular body 50. The opening 55 has a rectangular shape when viewed from the circumferential direction. In the opening 55, the engaging claw 30 of the inner member 2 is disposed. In a state where the torque in the fastening direction X is not applied to the outer member 5, the engaging claw portion 30 is disposed on the front side of the opening portion 55 in the fastening direction X. The openings 55 are provided at four locations at substantially equal intervals in the circumferential direction of the outer annular body 50.

  On the outer peripheral surface of the outer annular body 50, a mark portion 56 that is recessed in the radial direction is provided above the opening 55. The mark portion 56 forms a downward triangle as viewed from the circumferential direction. The lower vertex 56A of the downward triangle points to one end side in the width direction of the opening 55 (the rear side in the fastening direction X).

  As shown in FIGS. 2 and 4, the outer member 5 further has an arm body 60 protruding from the inner peripheral surface 50 </ b> Q of the outer annular body 50. The arm bodies 60 are provided at four locations at substantially equal intervals in the circumferential direction of the outer annular body 50.

  The arm body 60 includes a base portion 61 provided on the inner peripheral surface 50Q of the outer annular body 50 and an arm portion 65 that extends forward from the base portion 61 in the fastening direction X. The base portion 61 and the arm portion 65 are integrally formed. The lower surface of the base 61 is in contact with the upper surface 20T of the inner annular body 20.

  The base 61 has a pair of extending wall portions 62 that extend radially inward from the inner peripheral surface 50Q of the outer annular body 50 and are spaced apart from each other in the circumferential direction. The radially inner ends of the pair of extending wall portions 62 are connected by a connecting wall portion 63.

  The arm portion 65 is continuously formed on the upper portion of the connecting wall portion 63. In other words, a space portion 65S (see FIG. 2) is formed between the arm portion 65 and the upper surface 20T of the inner annular body 20. As described above, since the thickness of the arm portion 65 in the vertical direction is thinner than the thickness of the base portion 61 in the vertical direction, the arm portion 65 is easily bent.

As shown in FIG. 3, a downward projecting portion 70 extending downward is provided at the distal end portion of the arm portion 65.
As shown in FIG. 6, each downward protrusion 70 is continuously formed on the outer engagement surface 71 formed rearward in the fastening direction X and the radially outer end of the outer engagement surface 71. It has the 1st outer side sliding surface 72 and the 2nd outer side sliding surface 73 continuously formed in the front edge part of the fastening direction X of the 1st outer side sliding surface 72. As shown in FIG. Further, the downward projecting portion 70 is formed on the outer support surface 74 formed continuously at the front end portion in the fastening direction X of the second outer sliding surface 73 and the radially inner end portion of the outer support surface 74. And an inner side surface 75 formed continuously.

  In a state where the torque in the fastening direction X is not applied to the outer member 5 (the hatched state shown in FIG. 6), the outer engagement surface 71 is formed along the radial direction. The first outer sliding surface 72 is formed to be slightly inclined with respect to the circumferential direction so as to gradually go inward in the radial direction toward the rear in the fastening direction X. The second outer sliding surface 73 is formed along the circumferential direction. The outer support surface 74 is formed to be inclined with respect to the radial direction so as to go to the outer side in the radial direction and thus gradually toward the front in the fastening direction X. The inner side surface 75 is formed along the circumferential direction.

  2 and 3, the trap 110 includes a main body 111 formed in a bottomed cylindrical shape, and a discharge pipe 112 connected to an outlet (not shown) formed in a side portion of the main body 111. Have.

  A flange 113 extending outward in the radial direction is provided at the upper end portion of the main body 111 portion. An upper part of the flange 113 is provided with a trap-side fitting portion 114 that extends upward and is formed in an annular shape. The trap side fitting portion 114 is fitted into the lower fitting portion 22 of the inner member 2. Further, the flange 113 of the trap 110 and the flange 51 of the outer member 5 are connected so as not to be separated from each other in the vertical direction by a band 120 (see FIG. 1).

Next, a method of connecting the tank body 100 and the trap 110 of the kitchen with the nut 1 will be described.
First, as shown in FIG. 4, the nut 1 in which the inner member 2 is fitted to the outer member 5 is disposed outside the connecting body 102 of the tank body 100, and the outer ring of the outer member 5 of the nut 1 is arranged. The outer peripheral surface of the body 50 is gripped and rotated in the fastening direction X.

  Then, only the outer member 5 rotates, and the outer support surface 74 of the downward projecting portion 70 of the outer member 5 becomes the inner support surface 41 of the upward convex portion 40 of the inner member 2 as shown by a two-dot chain line in FIG. Abut. As a result, the outer member 5 and the inner member 2 rotate as a unit, and torque applied to the outer member 5 is transmitted to the inner member 2, so that the female screw portion 20X of the inner member 2 (see FIG. 2; the same applies hereinafter). .) Is screwed into the male screw portion 102X (see FIG. 2; the same applies hereinafter) of the coupling body 102.

  When the inner member 2 is screwed into the connecting body 102 by a predetermined amount and the torque applied to the outer member 5 is increased, the inner member 2 does not rotate, and the outer support surface 74 of the downward projecting portion 70 of the outer member 5 becomes inner. Only the outer member 5 rotates while sliding on the support surface 41 radially outward.

FIG. 7 is a plan view on the right side and a horizontal sectional view on the left side of the nut 1 in a state where torque in the fastening direction X is applied to the outer member 5.
As shown in the two-dot chain line in FIG. 6 and FIG. 7, when the outer support surface 74 of the downward projection 70 gets over the inner support surface 41 of the upward projection 40, the outer support surface 74 and the inner surface 75 of the downward projection 70. The corner portion 75 </ b> C slides forward in the fastening direction X on the outer surface 42 of the upward convex portion 40. At this time, the arm portion 65 of the outer member 5 is elastically deformed so as to bend outward in the radial direction.

  After the corner portion 75C reaches the corner portion 42C between the outer surface 42 and the inner engagement surface 43 of the upward convex portion 40, when the outer member 5 is further rotated, the upward convex portion 40 is a space portion below the arm portion 65. The arm portion 65 of the outer member 5 is elastically deformed so as to return to the original state, that is, radially inward. At this time, the arm portion 65 of the outer member 5 tends to return to the original state, and the outer engagement surface 71 of the downward projecting portion 70 collides (engages) with the inner engagement surface 43 of the upward convex portion 40, A collision sound is generated.

FIG. 8 is a plan view on the right side of the nut 1 and a horizontal cross-sectional view on the left side of the nut 1 in a state where the outer member 5 is further rotated in the fastening direction X as compared with FIG.
As shown in the two-dot chain line in FIG. 6 and FIG. 8, when the outer member 5 further rotates, the downward projecting portion 70 is disposed in front of the upward projecting portion 40 in the fastening direction X and radially inward.

FIG. 9 is a side view of the nut 1 in a state where torque in the fastening direction X is applied to the outer member 5.
As the outer member 5 is rotated relative to the inner member 2 in the fastening direction X, the engaging claw portion 30 of the inner member 2 is arranged on the front side of the opening portion 55 of the outer member 5 in the fastening direction X. From the state (see FIG. 5), the inside of the opening 55 is moved to the state where it is disposed at the rear end (predetermined position) 55B in the fastening direction X of the opening 55 shown in FIG. The engaging claw portion 30 is disposed below the apex 56 </ b> A on the lower side of the downward triangle of the mark portion 56 provided on the outer peripheral surface of the outer member 5. At this time, the engaging claw 30 collides with the rear end 55B of the opening 55, and a collision sound is generated.

  In this state, the engaging claw portion 30 is engaged with the rear end portion 55 </ b> B of the fastening portion X in the opening portion 55. Therefore, when further torque is applied to the outer member 5, the outer member 5 and the inner member 2 rotate together, the torque applied to the outer member 5 is transmitted to the inner member 2, and the inner member 2 is tightened. Is done.

  Next, the trap-side fitting portion 114 (see FIG. 2) of the trap 110 is fitted into the lower fitting portion 22 (see FIG. 3) of the inner member 2. And the flange 51 of the outer side member 5 and the flange 113 of the trap 110 are connected with the band 120 (refer FIG. 1). A pipe (not shown) is connected to the discharge pipe 112 of the trap 110.

Next, the case where the nut 1 is relaxed will be described.
FIG. 10 is a diagram illustrating a locus of the downward projecting portion 70 when the nut 1 is relaxed. FIG. 11 is a plan view on the right side of the nut 1 in the middle of relaxation, and a horizontal sectional view on the left side.
As shown in FIGS. 10 and 11, when torque in the relaxation direction (direction opposite to the fastening direction X) Y is applied to the outer member 5, the outer member 5 rotates in the relaxation direction Y, and the first of the downward projecting portions 70. The outer sliding surface 72 slides along the inner sliding surface 44 of the upward convex portion 40. When the outer member 5 further rotates, the second outer sliding surface 73 slides along the inner sliding surface 44 and returns to the position before fastening. At this time, the front side in the fastening direction X of the first outer sliding surface 72 and the inner sliding surface 44 is slightly in the circumferential direction so as to gradually go inward in the radial direction toward the rear of the fastening direction X. Therefore, it is easy to relax without applying a large torque.

In the nut 1 configured as described above, when a torque in the fastening direction X that is less than a predetermined amount is applied to the outer member 5, the inner member 2 and the outer member 5 rotate as a unit, and the outer member 5 Torque is transmitted to the inner member 2. As a result, the female screw portion 20X of the inner member 2 is fastened to the male screw portion 102X provided on the connecting body 102 of the tank body 100. When the torque in the fastening direction X equal to or greater than a predetermined amount is applied to the outer member 5, the inner member 2 does not rotate but the outer member 5 rotates. Therefore, the nut 1 can be properly fastened to the connecting body 102 of the tank body 100 with a predetermined amount of torque in the fastening direction X.
Further, at this time, the engaging claw portion 30 is disposed at the rear end portion in the fastening direction X of the opening portion 55 formed on the outer peripheral surface of the outer member 5. In addition, on the outer peripheral surface of the outer member 5, a lower vertex 56 </ b> A of the downward triangle of the mark portion 56 is provided so as to indicate the rear side of the fastening direction X of the opening 55. Therefore, the user visually confirms that the engaging claw portion 30 is disposed below the lower vertex 56 </ b> A of the downward triangle of the mark portion 56, so that the nut 1 is attached to the connecting body 102 of the tank body 100. It can be grasped that it was concluded properly.

  In addition, when the engaging claw 30 is disposed at the rear end of the fastening direction X of the opening 55 and the torque in the fastening direction X is applied to the outer member 5, the engaging claw 30 opens to the opening 55. Is engaged with the rear end portion 55B of the fastening direction X, and torque is transmitted from the outer member 5 to the inner member 2. Therefore, after the nut 1 is properly fastened to the connecting body 102 of the tank body 100, the nut 1 can be further tightened.

  The various shapes and combinations of the constituent members shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the embodiment described above, the mark portion 56 is provided above the opening 55 in the outer annular body 50, but the mark portion 56 may not be provided. When the nut 1 is fastened, it is only necessary that the user can grasp that the engaging claw portion 30 is disposed at a predetermined position.

  In the embodiment described above, when the nut 1 is fastened, the engaging claw 30 is engaged with the rear end 55B of the opening 55 in the fastening direction X, but the engagement claw 30 is engaged with the rear end 55B. It does not have to match.

  Moreover, in embodiment shown above, although the engaging claw part 30 arrange | positioned at the opening part 55 and the opening part 55 is each provided in four places, this invention is not limited to this, Even in 1-3 places. It may be provided at five or more locations. When the tank body 100 and the trap 110 are provided in the lower box of the kitchen and the opening 55 is arranged on the back plate side of the lower box, it is difficult to check the opening 55 from the front. It is preferable to provide 30 at two or more locations.

DESCRIPTION OF SYMBOLS 1 ... Nut 2 ... Inner member 5 ... Outer member 20 ... Inner annular body 20X ... Female thread part 21 ... Packing 22 ... Lower fitting part 30 ... Engagement claw part (projection part)
40 ... Upward convex portion 41 ... Inner support surface 42 ... Outer surface 43 ... Inner engagement surface 44 ... Inner sliding surface 50 ... Outer annular body 51 ... Flange 55 ... Opening 56 ... Marking portion 60 ... Arm body 61 ... Base 65 ... arm part 65S ... space 70 ... downward projection 71 ... outer engagement surface 72 ... first outer sliding surface 73 ... second outer sliding surface 74 ... outer support surface 75 ... inner side surface 100 ... tank body 101 ... top Plate 102 ... Connector (fastening object)
102X ... male screw part 110 ... trap 111 ... main body 112 ... discharge pipe 114 ... trap side fitting part 120 ... band O ... axis X ... fastening direction Y ... relaxation direction

Claims (3)

An inner member having a female screw portion fastened to a male screw portion provided on the fastening object;
An outer member that is rotatably mounted to the inner member on a radially outer side of the inner member;
On the outer peripheral surface of the outer member, an opening that penetrates in the radial direction is formed,
The inner member has a protrusion disposed in the opening,
When a torque in a fastening direction less than a predetermined amount is applied to the outer member, the inner member and the outer member rotate as a unit, and the torque is transmitted from the outer member to the inner member,
When the torque in the fastening direction equal to or greater than the predetermined amount is applied to the outer member, the inner member does not rotate, the outer member rotates, and the protrusion is disposed at a predetermined position of the opening. A nut characterized by that.   The nut according to claim 1, wherein a mark portion corresponding to the predetermined position where the protrusion portion is disposed in the opening is provided on an outer peripheral surface of the outer member.   When torque in the fastening direction is applied to the outer member in a state where the protrusion is disposed at the predetermined position of the opening, the protrusion is placed at the rear end of the opening in the fastening direction. The nut according to claim 1 or 2, wherein the nut is engaged and the torque is transmitted from the outer member to the inner member.

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