JP2022127073A - Bolt and bolt tightening structure - Google Patents

Abstract

To provide a bolt which can avoid influence caused by heat strain of a tightened body and prevent breakage without being protruded significantly by using a collar etc., and to provide a bolt tightening structure.SOLUTION: A bolt 10 has: a columnar shaft part 30; and a head part 20 provided at one end of the shaft part 30. The shaft part 30 has a second yoke part 40 connected to the head part 20. The head part 20 has a first yoke part 60 connected to the shaft part 30. The second yoke part 40 and the first yoke part 60 are connected through a cross pin 50 as an oscillating mechanism so as to allow the head part 20 to swing relative to the shaft part 30 and function as a universal joint. The oscillating mechanism allows a seating surface 22a of the head part 20 of the bolt 10 to follow a flange surface of an exhaust manifold. Thus, even if stress which causes the head part 20 to swing is repeatedly applied, the head part 20 is not broken.SELECTED DRAWING: Figure 1

Description

The present invention relates to a bolt provided with an oscillating mechanism and a bolt tightening structure using the bolt.

For example, in an exhaust system of an automobile engine, an exhaust manifold that joins the exhaust gas from each cylinder is attached to the engine by bolting. When the engine is stopped and left for a long time, the temperature of the exhaust manifold drops to the ambient temperature (the temperature of the air). Further, when the engine is in operation, the temperature of the exhaust manifold rises to, for example, 800[° C.] or higher. Therefore, when the engine is repeatedly operated and stopped, the exhaust manifold may repeat expansion and contraction due to the temperature difference, and may repeat deformation and restoration due to thermal strain caused by the temperature difference. When the exhaust manifold repeatedly deforms and restores due to the occurrence of thermal strain, the inclination angle of the surface of the exhaust manifold with which the bearing surface of the bolt that fastens the exhaust manifold is in contact increases or decreases. sometimes. In this case, the stress that rocks the head of the bolt is repeatedly applied to the shank of the bolt, and there is a possibility that the head of the bolt will break.

For this reason, it is conventionally known to attach a collar to the bolt. Specifically, by sandwiching the collar between the exhaust manifold flange and the bolt, the bearing surface of the bolt is separated from the exhaust manifold flange, thereby avoiding the influence of thermal strain on the exhaust manifold flange. For example, Patent Literature 1 discloses a technique for reducing the influence of thermal strain of the flange of the exhaust manifold on the bolt by providing a gap between the inner peripheral surface of the collar and the shaft of the bolt.

JP-A-8-246868

However, using collars to fasten the bolts has the advantage of avoiding the effects of thermal strain on the flange of the exhaust manifold, but the disadvantage is that the bolts that protrude greatly from the collars interfere with other parts. Occur. Recent engines are designed to be extremely tight, so it is not very desirable for the bolt to protrude greatly.

The present invention has been devised in view of this point, and it is possible to avoid the influence of thermal strain on the tightened body and prevent breakage without using a collar or the like to make the bolt protrude greatly. It is an object of the present invention to provide a bolt and a bolt tightening structure capable of achieving this.

In order to achieve the above object, a first invention of the present invention is a bolt having a cylindrical shaft portion and a head portion provided at one end of the shaft portion, wherein the shaft portion has a The side has a shaft side connecting portion that is connected to the head portion, and the other end side has a threaded portion. It has a large-diameter portion with a large outer diameter, and has a head-side connecting portion connected to the shaft portion on the other end side, so that the head portion can swing with respect to the shaft portion. , in which the shaft side connecting portion and the head side connecting portion are connected as a swinging mechanism.

Next, a second invention of the present invention is the bolt according to the first invention, wherein the outer diameter of the head-side connecting portion is set smaller than the outer diameter of the shaft portion. is.

Next, a third invention of the present invention is the bolt according to the first invention or the second invention, wherein the swing mechanism is a universal joint.

Next, a fourth invention of the present invention is a bolt tightening structure for tightening an object to be tightened against a mating member to be tightened using the bolt according to the first to third inventions, The mating member is provided with a threaded hole into which the threaded portion of the shaft portion is screwed, and the member to be fastened is provided with a communication hole through which the shaft portion is inserted and which communicates with the threaded hole. In a state in which the shaft portion of the bolt is inserted through the communication hole, the threaded portion is screwed into the screw hole, and the bolt is used to tighten the object to be tightened to the mating member, the The bolt tightening structure, wherein the inner diameter of the communication hole at the head-side connecting portion is set larger than the outer diameter of the head-side connecting portion and smaller than the outer diameter of the large-diameter portion. be.

According to the first invention, even if the object to be tightened, for example, an exhaust manifold, is repeatedly deformed and restored due to the occurrence of thermal strain, the bearing surface of the head of the bolt is caused to move to the exhaust manifold by the swing mechanism. Since the head follows the flange surface of the head, the head is not broken even if the stress for rocking the head is repeatedly applied. Therefore, without using a collar or the like to protrude the bolt greatly, it is possible to avoid the effects of thermal strain on the object to be fastened and prevent breakage and the like.

According to the second invention, when the object to be fastened is tightened to the mating member by the bolt, the mating member has a threaded hole into which the shank of the bolt is screwed, and the shank is inserted into the threaded hole in the to-be-tightened body. Communicating holes leading to are provided respectively. In such a case, even if the inner diameters of the communication hole and the screw hole are the same, the outer diameter of the head-side connecting portion is within the outer diameter of the shaft even if the head is rocked. Therefore, interference between the head-side connecting portion and the inner wall of the communication hole can be avoided.

According to the third aspect of the invention, with the universal joint, the torque received by the head of the bolt can be transmitted to the shaft while the head of the bolt is held swingably with respect to the shaft. It is suitable as a mechanism.

According to the fourth invention, even if the object to be fastened is repeatedly deformed and restored due to thermal strain, the bearing surface of the bolt head follows the surface of the object to be fastened by the swing mechanism. Therefore, the head is not broken even if stress for rocking the head is repeatedly applied. In addition, due to the size relationship between the diameters of the communication hole and the head-side connecting portion provided in the object to be fastened, interference between the head-side connecting portion and the inner wall of the communication hole is avoided when the head swings. be able to.

1 is an exploded perspective view of a bolt according to a first embodiment; FIG. FIG. 3 is a view showing an exhaust manifold, which is a tightening target of a bolt, and a cylinder head, which is a tightening partner. FIG. 3 is a cross-sectional view along the line III-III in FIG. 2 when the bolt according to the first embodiment is used for tightening; FIG. 5 is a diagram for explaining the rocking of the head of the bolt according to the first embodiment when thermal strain occurs in the flange; FIG. 8 is an exploded perspective view of a bolt according to a second embodiment; FIG. 3 is a cross-sectional view along the line III-III in FIG. 2 when the bolt according to the second embodiment is used for tightening; FIG. 10 is a diagram for explaining the rocking of the head of the bolt according to the second embodiment when thermal strain occurs in the flange; FIG. 10 is a diagram showing a modification of the bolt having a swingable swing mechanism; FIG. 11 shows a socket for turning a modified bolt;

<First embodiment>
A method according to an embodiment of the present invention will be described below.

FIG. 1 is an exploded perspective view of a bolt 10 according to this embodiment. As shown in FIG. 1 , the bolt 10 has a cylindrical shaft portion 30 and a head portion 20 provided at one end of the shaft portion 30 . The shaft portion 30 includes a threaded portion 31 having a male thread and a cylindrical portion 32 having no external thread. The head portion 20 has a large diameter portion 25 consisting of a hexagonal portion 21 and a seat portion 22 that receives torque from the tool. has 40. The outer diameter A of the large diameter portion 25 is set larger than the outer diameter B of the shaft portion.

In the bolt 10, the first yoke portion 60 and the second yoke portion 40 are connected to form a universal joint 70 as a swing mechanism so that the head portion 20 can swing with respect to the shaft portion 30. there is Specifically, the universal joint 70 includes a cross pin 50 having four pins 51 to 54 that protrude in a cross shape, and two coaxial pins 52 and 54 in the cross pin 50 that are rotatable as a first axis. It is composed of a first yoke portion 60 for support and a second yoke portion 40 for rotatably supporting the remaining two coaxial pins 51 and 53 as a second axis.

Specifically, the first yoke portion 60 is composed of two projections 61 and 62 projecting from the upper surface 32a of the cylindrical portion 32 of the shaft portion 30. The outer surface 61a of the projection 61 and the outer surface 62a of the projection 62 is continuous with the outer peripheral surface 32b of the .

Specifically, the second yoke portion 40 is composed of two protrusions 41 and 42 that protrude from the seat surface 22a of the seat portion 22 of the head portion 20, and has an outer diameter C that is the maximum width from the outer surface 41a to the outer surface 42a. , is the same as the outer diameter B of the shaft portion 30 . By inserting the pins 51 to 54 of the cross pin 50 into the respective pin holes provided in the protrusions 41, 42 and the protrusions 61, 62, the universal joint 70 functions. The outer surfaces 41a and 42a of the projections 41 and 42 and the outer surfaces 61a and 62a of the projections 61 and 62 are curved surfaces, and the tips of the pins 51 to 54 inserted into the respective pin holes are aligned with the curved surfaces. shape.

FIG. 2 is a diagram showing an exhaust manifold 100 corresponding to a tightened body of the bolt 10 and a cylinder head 130 corresponding to a mating member to be tightened. FIG. 3 is a cross-sectional view along line III--III in FIG. 2, the bolts 10 that fasten the flange 110 to the cylinder head 130 are omitted. As shown in FIGS. 2 and 3, the exhaust manifold 100 has a flange 110 and is attached to the cylinder head 130 with a gasket 120 sandwiched between the flange 110 and the cylinder head 130 .

The cylinder head 130 is provided with a plurality of threaded holes 132 into which the threaded portion 31 of the shaft portion 30 is screwed. 121 are provided respectively. When the shaft portion 30 of the bolt 10 is inserted into the communication holes 111 and 121 and the threaded hole 132 and screwed, the bearing surface 22a of the head portion 20 comes into contact with the surface 113 of the flange 110, and further screwing causes the cylinder to rotate. The flange 110 is tightened together with the gasket 120 against the head 130 .

As shown in FIG. 3, the cylinder head 130 is provided with the threaded hole 132 into which the threaded portion 31 of the shaft portion 30 of the bolt 10 is screwed, as described above. Communication holes 111 and 121 corresponding to the screw holes 132 are provided in the flange 110 and the gasket 120 . Here, the inner diameter R of the communication holes 111 and 121 is set larger than the outer diameter C of the second yoke portion 40 . Therefore, the threaded portion 31 of the shaft portion 30 of the bolt 10 is screwed into the threaded hole 132 through the communication holes 111 and 121, and the flange 110 and the gasket 120 are pressed against the cylinder head 130 by the bearing surface 22a of the head portion 20. In this case, a gap L exists between the second yoke portion 40 and the inner wall 112 of the communication hole 111 .

4A and 4B are diagrams for explaining the rocking of the head portion 20 of the bolt 10 when the flange 110 is thermally strained. As shown in FIG. 4, when the engine is running, the cylinder head 130, the gasket 120, and the flange 110 are all heated to a high temperature, and thermal expansion causes thermal strain. , the surface 113 of the flange 110 is deformed. Then, when the engine stops, the thermal expansion subsides and the flange 110 restores its original shape. In the case of conventional bolts, such deformation and restoration of the surface 113 of the flange 110 causes stress to concentrate under the neck of the bolt, which may lead to serious problems such as breakage of the bolt.

There are various ways in which the surface 113 of the flange 110 is deformed. In the first place, the processing accuracy of the flange 110 and the gasket 120 is poor. It is also said to return to In any case, the shape of the flange 110 and the gasket 120 arranged around the engine changes depending on the state during cooling and the state during heating, and the surface 113 of the flange 110 deforms (restores). A collar was used without the face 22a directly contacting the flange 110. FIG.

However, in the bolt 10 according to the present embodiment, the head portion 20 is joined to the shaft portion 30 by the universal joint 70, so that the bolt 10 has a swinging mechanism. The head 20 can be moved to follow the surface 113 of the flange 110 while maintaining the force. Moreover, at that time, due to the clearance L, the protrusions 41 and 42 and the inner wall 112 of the communication hole 111 do not interfere with each other. That is, when the head 20 swings as shown in FIG. 4 , the root portion of the protrusion 41 and the tip portion of the protrusion 42 protrude from the extension line of the cylindrical portion 32 of the shaft portion 30 . Therefore, if there is no gap L and the projections 41 and 42 are close to the inner wall 112, interference will occur. The gap L is provided to avoid such interference.

As described above, when the seat surface 22a of the bolt 10 is brought into direct contact with the flange 110, even if the surface 113 of the flange 110 is deformed due to the heat of the engine, the universal joint 70 can absorb the deformation. Since the stress is absorbed, the stress is not concentrated under the neck of the bolt 10. - 特許庁Therefore, according to the bolt 10 according to the present embodiment, the influence of the thermal strain of the exhaust manifold 100, which is the object to be tightened, can be avoided without making the bolt 10 protrude greatly using a collar or the like, and the head portion of the bolt 10 can be reduced. 20 can be prevented from being broken.

<Second embodiment>
Next, a bolt 200 according to a second embodiment of the invention will be described. The bolt 200 according to the present embodiment is different from the first embodiment in that the outer diameter W of the second yoke portion 240 is smaller than the outer diameter B of the shaft portion 30 . It should be noted that descriptions of matters already described in the first embodiment will be omitted as appropriate.

FIG. 5 is an exploded perspective view of the bolt 200 according to this embodiment. As shown in FIG. 5, the second yoke portion 240 consists of two protrusions 241 and 242 protruding from the seat surface 22a of the head portion 20, as in the first embodiment. The outer diameter W from the outer surface 241a of the projection 241 to the outer surface 242a of the projection 242 is set smaller than the outer diameter B of the shaft portion 30 unlike the first embodiment.

The first yoke portion 260 includes two protrusions 261 and 262 protruding from the upper surface 32a of the cylindrical portion 32 of the shaft portion 30, as in the first embodiment. The width from the outer surface 261a of the protrusion 261 to the outer surface 262a of the protrusion 262 is matched with the outer diameter W from the outer surface 241a of the protrusion 241 to the outer surface 242a of the protrusion 242. As shown in FIG. By inserting the pins 251 to 254 of the cross pin 250 into the respective pin holes provided in the protrusions 241, 242 and the protrusions 261, 262, the universal joint 75 functions. The lengths of the pins 251 to 254 of the cross pin 250 are set shorter than those in the first embodiment so as to match the widths described above.

FIG. 6 is a cross-sectional view along line III--III in FIG. 2 when bolt 200 is used. As shown in FIG. 6, the cylinder head 130 is provided with a threaded hole 132 into which the threaded portion 31 of the shaft portion 30 of the bolt 200 is screwed. Communication holes 115 and 125 corresponding to the screw holes 132 are provided in the flange 110 and the gasket 120 . Here, the inner diameter R1 of the communication holes 115 and 125 is set to be the same as the inner diameter R2 of the screw hole 132 . However, as described above, the outer diameter W from the outer surface 241a of the protrusion 241 to the outer surface 242a of the protrusion 242 is set to be smaller than the outer diameter B of the shaft portion 30, so naturally the second yoke portion 240 and the communicating hole A gap L is provided in the inner wall 116 of 115 .

7A and 7B are diagrams for explaining the rocking of the head portion 20 of the bolt 200 when the flange 110 is thermally strained. As shown in FIG. 7, the bolt 200 according to the present embodiment has a head portion 20 that is joined to the shaft portion 30 by a universal joint 70, as in the first embodiment. As a result of having the mechanism, it is possible to move the head 20 following the surface 113 of the flange 110 while maintaining the pressing force of the seat surface 22 a of the bolt 200 .

Moreover, at that time, the protrusions 241 and 242 do not interfere with the inner wall 116 of the communication hole 115 due to the clearance L. In other words, the base portion of the protrusion 241 and the tip portion of the protrusion 242 are originally located inside the extension line of the columnar portion 32 of the shaft portion 30, so even if the head portion 20 swings, they do not protrude from the extension line. .

As described above, when the bolts 200 are used to tighten the exhaust manifold 100, which is the object to be tightened, to the cylinder head 130, which is the mating member, the cylinder head 130 has the screw holes 132 into which the shaft portions 30 of the bolts 200 are screwed. The flange 110 and the gasket 120 of 100 are provided with communication holes 115 and 125 through which the shaft portion 30 is inserted and communicated with the screw hole 132, respectively. Even if the communication holes 115 and 125 and the screw hole 132 have the same diameter, the outer diameter W of the second yoke portion 240 is within the outer diameter B of the shaft portion 30, so that the second yoke portion Interference between 240 and the inner wall 116 of the communication hole 115 can be avoided.

The bolts 10 and 200 of the present invention are not limited to the appearance, configuration, structure, etc. described in the present embodiment, and various modifications, additions, and deletions are possible without changing the gist of the present invention. Also, although the cylinder head 130, the exhaust manifold 100, and the gasket 120 have been described as examples of the objects to be tightened by the bolts 10 and 200 and their counterparts, the objects are not limited to these. For example, even if the processing accuracy of the object to be fastened is poor and the surface of the object to be fastened against which the bearing surface 22a of the bolt 10, 200 abuts is not perpendicular to the screw hole before thermal strain. Since variation can be absorbed by the swinging motion of the head 20, even such an object to be tightened can be tightened.

Further, in each of the above-described embodiments, the bolt head and the shaft are joined by a universal joint. Specifically, as shown in FIG. 8, a ball portion 310 (shaft portion side connecting portion) is provided on the upper surface 32a of the cylindrical portion 32 of the shaft portion 30, and a ball receiver 320 is provided on the bearing surface 22a of the head portion 20. By providing the (head side connecting portion), the bolt 300 can also be configured such that the head portion 20 swings with respect to the shaft portion 30 .

In addition, a hexagonal hole 330 is provided from the head 20 to the ball 310 so that torque can be applied to both the head 20 and the shank 30 using a socket 400 as shown in FIG. That is, the socket 400 has hexagonal faces 410 corresponding to the hexagonal portion 21 of the head 20 and has a hexagonal rod 420 corresponding to the hexagonal hole 330 . The socket 400 can be attached to a separately prepared handle and used as a tool for turning the bolt 300 .

In addition, although a cross-shaped cross pin is exemplified as the shape of the cross pin, any cross pin may be used as long as it has four pins protruding in a cross shape. A cross pin may be used. Also, bearings can be incorporated into pin holes in the first yoke portion 60 and the second yoke portion 40 in order to swing the head 20 more smoothly.

Also, although the large-diameter portion 25 of the head portion 20 has been described as being composed of the hexagonal portion 21 and the seat portion 22, it may be composed of only the hexagonal portion 21. FIG. In this case, the outer diameter of the hexagonal portion 21 is made larger than the outer diameter B of the shaft portion 30, the surface of the hexagonal portion 21 on the shaft portion 30 side is used as a bearing surface, and the second yoke portions 40 and 240 are formed from the bearing surface. It should be.

10 Bolt 20 Head 21 Hexagonal portion 22 Seat 22a Seat surface 25 Large diameter portion 30 Shaft 31 Threaded portion 32 Cylindrical portion 32a Upper surface 32b Peripheral surface 40 Second yoke portion 41 Projection 41a External surface 42 Projection 42a External surface 50 Cross pin 60 First Yoke portion 61 Projection 61a Outer surface 62 Projection 62a Outer surface 70 Universal joint 100 Exhaust manifold 110 Flange 111 Communication hole 112 Inner wall 113 Surface 120 Gasket 130 Cylinder head

Claims (4)

A bolt having a cylindrical shaft and a head provided at one end of the shaft,
The shaft has a shaft-side connecting portion connected to the head on one end side and a threaded portion on the other end side,
The head has, on one end side, a large-diameter portion having an outer diameter larger than the outer diameter of the shaft portion, and on the other end side, a head-side connecting portion connected to the shaft portion. has
The shaft-side connecting portion and the head-side connecting portion are connected as a swing mechanism so that the head can swing with respect to the shaft,
bolt. A bolt according to claim 1,
The outer diameter of the head-side connecting portion is set smaller than the outer diameter of the shaft portion,
bolt. 3. The bolt according to claim 1 or 2,
The swing mechanism is a universal joint,
bolt. A bolt tightening structure that uses the bolt according to any one of claims 1 to 3 to tighten an object to be tightened to a mating member to be tightened,
The mating member is provided with a threaded hole into which the threaded portion of the shaft portion is screwed,
The object to be fastened is provided with a communication hole through which the shaft portion is inserted and which communicates with the screw hole,
In a state in which the shaft portion of the bolt is inserted through the communication hole, the threaded portion is screwed into the threaded hole, and the bolt is used to tighten the object to be tightened to the mating member,
The inner diameter of the communication hole at the location of the head-side connecting portion is set larger than the outer diameter of the head-side connecting portion and smaller than the outer diameter of the large-diameter portion.
Bolt tightening structure.

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