WO2022210239A1

WO2022210239A1 - Pipe structure

Info

Publication number: WO2022210239A1
Application number: PCT/JP2022/013861
Authority: WO
Inventors: 靖人富永
Original assignee: いすゞ自動車株式会社
Priority date: 2021-03-29
Filing date: 2022-03-24
Publication date: 2022-10-06
Also published as: JP2022152711A; JP7416000B2

Abstract

A pipe structure 10 comprises a pipe 11 and a boss portion 12 into which a bolt 15 is inserted. The pipe 11 and the boss portion 12 are provided as one body with an overlap between a distal portion of the boss portion 12 and a part of a lower portion of the pipe 11 positioned immediately above the distal portion. A protruding length L1 of the boss portion 12 corresponds to a length such that a distal end 12a is located at a position beyond a lowest point 18 and before a most lateral point 19 in the inner peripheral surface of the pipe 11. The lower portion of the pipe 11 is structured such that a weir portion 21 where a pipe wall has a bulge 20 protruding from the outside to the inside in the pipe radial direction and a bypass portion 22 where the pipe wall forms an arc shape protruding from the inside to the outside in the pipe radial direction are arranged side by side across the lowest point 18.

Description

piping structure

The present disclosure relates to a piping structure, and more particularly, to a piping structure including piping and a boss for assembling the piping.

It is known that if condensed water accumulates in the middle of the EGR passage (exhaust recirculation passage), the condensed water containing exhaust components will corrode the pipes that make up the EGR passage. In relation to this, a technique has been disclosed in which the EGR passage is inclined downward from the upstream side to the downstream side to avoid accumulation of condensed water in the middle position (see, for example, Patent Document 1).

International publication number WO2013/021779

By the way, the pipes arranged along the wall surface of the engine are fixed by inserting screws such as bolts into the bosses (also called welding nuts) that are connected to the top and bottom of the pipes. If the boss is separated from the pipe in order to maintain the shape of the pipe, the boss may interfere with other parts. However, considering the fastening operation using screws such as bolts, the distance between the outer peripheral surface of the pipe and the outer peripheral surface of the boss portion cannot be increased.

On the other hand, in order to avoid interference with other parts, it is possible to shorten the distance between the bosses by changing the shape of the piping. However, if only the shape of the pipe around the boss portion is changed, the shape will be different from the shape of the pipe before and after that portion. Therefore, there is a risk that condensed water will accumulate in the boundary portion. In addition, applying the shape of the boundary portion to the shape of the entire pipe increases the cost, and in addition, it becomes impossible to incorporate a device for the shape of a cylindrical pipe in the middle of the pipe.

An object of the present disclosure is to provide a piping structure that prevents fluid from accumulating inside while avoiding interference with surrounding parts.

A piping structure according to one aspect of the present disclosure that achieves the above object includes a pipe arranged along a wall surface, and a pipe arranged below the pipe and protruding from the wall surface in a direction intersecting with the axial direction of the pipe. and a boss into which a screw is inserted from the tip thereof, wherein a portion of the lower part of the pipe located immediately above the tip of the boss and the tip of the pipe are integrated and overlapped, The protrusion length from the wall surface to the tip of the boss portion is such that the tip exceeds the lowest point on the inner peripheral surface of the pipe located directly above the boss portion and is farthest apart from the lowest point in the orthogonal direction. The lower part of the pipe is a weir part having a convex bulge from the outer side to the inner side in the pipe radial direction with the lowest point as a boundary. and a roundabout portion in which the pipe wall forms a convex arc from the inner side to the outer side in the pipe radial direction.

According to one aspect of the present disclosure, the piping and the boss portion are integrated and overlapped, so that the piping and the boss portion are close to each other, and interference with peripheral components can be avoided. Furthermore, according to one aspect of the present disclosure, a portion where the shape of the pipe is changed and a portion where the shape of the pipe is not changed due to the close proximity of the pipe and the boss exist on the boundary of the lowest point of the pipe. Therefore, since the fluid that tries to stay in the part whose shape has been changed flows into the part that has not been changed, it is possible to avoid the fluid from accumulating inside the pipe.

FIG. 1 is a perspective view illustrating the piping structure of the embodiment. FIG. 2 is an enlarged cross-sectional view of the hatched cross section in FIG. 3 is a cross-sectional view of the bulge in FIG. 1 in the XZ plane.

An embodiment of the piping structure in the present disclosure will be described below. In the figure, the X direction is the pipe axis direction of the pipe 11, the Y direction is the direction perpendicular to the pipe axis direction of the pipe 11, the axial direction of each of the bosses 12 to 14 and the bolt 15, and the Z direction is the vertical direction. respectively. The white arrows in the figure indicate the flow of the recirculated exhaust. In the drawings, the dimensions of the members are changed so that the configuration is easy to understand, and they do not necessarily match those actually manufactured.

In the present disclosure, the term "screw" refers to a male screw having a helical groove on the side surface of a cylindrical body. In the embodiment, bolts 15 are employed as screws. The holes of the bosses 12 to 14 into which the screws are inserted are formed with spiral grooves directly on the cylindrical surface and have female threads to be screwed with the male threads, unless otherwise specified. A nut having an opening formed with an internal thread that engages with the external thread is shown fitted in the central portion.

As exemplified in FIG. 1, the piping structure 10 of the embodiment is assembled to the side of the engine by screwing bolts 15 onto bosses 12 to 14 of a piping 11 that constitutes part of an exhaust gas recirculation passage of an engine (not shown). It is. The exhaust gas recirculation passage is a passage for recirculating exhaust gas from an exhaust passage (not shown) to the intake passage. The recirculated exhaust gas flowing through the exhaust gas recirculation passage passes through the communication pipe 1 branched from the exhaust passage (not shown) and the flow rate control valve 2 and flows through the curved pipe 16 and the pipe 11 in this order. The communication pipe 1 slopes downward toward the flow control valve 2 . The flow control valve 2 is configured with a butterfly valve (not shown).

The piping structure 10 comprises a piping 11, bosses 12-14, a bent piping 16, and a flange 17. The pipe 11 is composed of a circular pipe extending in the X direction, and its tip communicates with a curved pipe 16 indicated by a dotted line in the drawing. Bosses 12-14 protrude from flange 17 in the Y direction. The boss portions 12 to 14 form a cylindrical cylindrical body when viewed in the X direction. A bolt 15 is inserted from the tip of each of the bosses 12 to 14 . Bosses 12 to 14 surround the tip of bent pipe 16 . The boss portion 12 is arranged directly below the pipe 11, the boss portion 13 is arranged directly above the pipe 11, and the boss portion 14 is arranged elsewhere. The flange 17 has a plate-like shape projecting radially from the entire periphery of the tip of the curved pipe 16 . In the present disclosure, the wall surface is the surface with which the outer peripheral surface of the pipe 11 is in contact, and indicates the surface from which the boss portions 12 to 14 protrude. In this embodiment, the wall surface is the surface facing the front side of the flange 17 in the Y direction. The pipe 11 and the bent pipe 16 and the communication pipe 1 are communicated with each other by fastening the flange 17 stacked in the Y direction, the housing of the flow control valve 2, and the flange 3 with bolts 15, respectively.

As illustrated in FIG. 2, in the piping structure 10, a part of the lower portion of the pipe 11 and the tip portion of the boss portion 12 are integrated and overlapped, and the lower portion of the pipe 11 swells with the lowest point 18 as a boundary. A dam portion 21 having 20 formed thereon and a detour portion 22 are arranged side by side.

The lower part of the pipe 11 indicates the lower part in the Z direction of the pipe 11, and the tip part of the boss part 12 indicates the left part in the Y direction including the tip 12a. The part of the lower portion of the pipe 11 is a portion located directly above the tip of the boss portion 12 .

In the present disclosure, integration indicates a state in which each member is seamlessly connected. The piping structure 10 of this embodiment is constructed by integrating the piping 11, the boss portions 12 to 14, the bent piping 16, and the flange 17, respectively. As the piping structure 10, a casting manufactured by pouring a liquid metal material into a mold is exemplified.

A portion of the lower portion of the pipe 11 and the tip portion of the boss portion 12 are integrated and overlapped means that the minimum value D1 of the thickness in the pipe radial direction of the integrated and overlapped portion is affected by the integration. It shows a state in which the thickness D2 of the pipe 11 and the ring width D3 of the boss portion 12 are smaller than the sum of the thickness D2 of the pipe 11 and the ring width D3 of the boss portion 12. The integrally overlapped portion becomes a shared portion of the pipe 11 and the boss portion 12, and has an inner peripheral surface of the pipe 11, a tip 12a of the boss portion 12, and a portion into which the bolt 15 of the boss portion 12 is inserted. . The minimum value D1 can be reduced to the larger value of the pipe thickness D2 and the ring width D3. In this embodiment, the ring width D3 is adopted as the minimum value D1.

The lowest point 18 is a point that indicates the lowest portion on the inner peripheral surface of the pipe 11 directly above the boss portion 12 in a cross-sectional view on the YZ plane. The lowest point 18 is a point that indicates the lowest position when the engine with the piping structure 10 is mounted on the vehicle. The most lateral point 19 is a point that indicates a portion located farthest in the Y direction from the lowest point 18 on the inner peripheral surface of the pipe 11 directly above the boss portion 12 in a cross-sectional view on the YZ plane, and is located on the leftmost side in the drawing. It is a point that indicates the site where it is located.

The bulge 20 is formed by the pipe wall of the pipe 11 protruding from the outside in the pipe radial direction to the inside. The pipe wall of the pipe 11 on which the bulge 20 is formed has a convex inner peripheral surface and a concave outer peripheral surface. The inner peripheral surface of the pipe 11 on which the bulge 20 is formed has a shape obtained by rotating an ellipse whose long axis is directed in the X direction around the long axis and halving a spheroid by a plane passing through the long axis. form. The bulge-formed outer peripheral surface forms a shape along the space so that the space forming a cylindrical body whose column axis direction is oriented in the X direction is held at the tip 12a of the boss portion 12 . The bulge 20 has an apex 23, a first slope 24, an end 25 of the first slope 24, and a second slope 26 on its inner peripheral surface. Bulge 20 has a flat surface 27 and a curved surface 28 on its outer peripheral surface.

The bulge 20 is formed by integrally overlapping the lower portion of the pipe 11 and the tip of the boss portion 12 with respect to the inner peripheral surface of other parts, and the protrusion length L1 of the boss portion 12 is such that the tip 12a is the lowest point 18 , and a length that does not exceed the most lateral point 19 of the pipe 11 . The bulge 20 is formed by forming a depression 20 on the outer peripheral surface of the pipe 11 to secure a space for fastening the bolt 15 .

The projection length L1 is the length from the left side of the flange 17 in the Y direction to the tip 12a of the boss portion 12. In the present disclosure, a position beyond the lowest point 18 is a position beyond a vertical line on the YZ plane passing through the lowest point 18 . A position not exceeding the sidemost point 19 is a position not exceeding a vertical line on the YZ plane passing through the sidemost point 19 .

The weir portion 21 is a portion where the bulge 20 is formed among the portions divided by the XZ plane where the lower portion of the pipe 11 passes through the lowest point 18 . The detour portion 22 is a portion where the bulge 20 is not formed among the portions divided by the XZ plane where the lower portion of the pipe 11 passes through the lowest point 18 . In the detour portion 22, the pipe wall of the pipe 11 forms a convex arc shape from the inner side to the outer side in the pipe radial direction. It is desirable that the detour portion 22 has a cylindrical inner peripheral surface of the pipe 11 .

A vertex 23 indicates a portion of the inner peripheral surface of the bulge 20 that is located furthest inside the pipe 11 .

The first slope 24 is the inner peripheral surface of the pipe 11 on which the bulge 20 is formed, and is a surface that slopes downward from the vertex 23 toward the lowest point 18 side terminal 25 of the terminal ends of the bulge 20 . The first slope 24 is a surface of a shape obtained by further cutting a halved spheroid along a plane passing through the major axis. As shown in the drawing, the first slope 24 is a surface that slopes downward from the vertex 23 toward the lowest point 18 in a cross section on the YZ plane passing through the vertex 23 .

A terminal end 25 of the first slope 24 is arranged before the lowest point 18 . The first slope 24 is the inner peripheral surface of the pipe 11 on which the bulge 20 is formed, and is a slope formed by the inner peripheral surface protruding from the outer side to the inner side in the pipe radial direction. The inner peripheral surface of another pipe 11 without the bulge 20 is a cylindrical surface formed by denting from the inner side to the outer side in the pipe radial direction. A terminal end 25 of the first slope 24 is a boundary between a portion where the inner peripheral surface of the pipe 11 protrudes toward the inside and a portion where the inner peripheral surface is recessed toward the outside.

The second slope 26 is the inner peripheral surface of the pipe 11 on which the bulge 20 is formed. It is a surface that slopes downward from the opposite end to the vertex 23 . The second slope 26 is a surface of a shape obtained by further cutting the halved spheroid by a plane passing through the major axis. As shown in the drawing, the second slope 26 is a surface that slopes downward toward the vertex 23 in a cross section on the YZ plane passing through the vertex 23 .

The weir portion 21 has a second slope 26 and a first slope 24 arranged in the pipe circumferential direction toward the lowest point 18 . The weir portion 21 forms a slope that slopes downward toward the lowest point 18 over the entire inner peripheral surface. When the apex 23 intervenes in the middle of the slope as shown in the figure, the slope similarly slopes downward toward the lowest point 18 .

The flat surface 27 is the outer peripheral surface of the pipe 11 on which the bulge 20 is formed, and is a flat surface perpendicular to the X direction. The flat surface 27 constitutes part of the tip 12 a of the boss portion 12 . The flat surface 27 is a surface that comes into contact with the bearing surface 15 a of the bolt 15 when the bolt 15 is inserted into the boss portion 12 .

The curved surface 28 is the outer peripheral surface of the pipe 11 on which the bulge 20 is formed, and forms a convex cylindrical surface from the bottom to the top in the Z direction. The curved surface 28 is a surface that does not protrude inside the space of the cylindrical body that is formed ahead of the tip 12a of the boss portion 12 . In other words, the curved surface 28 does not interfere with the bolt 15 that is inserted into and removed from the boss portion 12 .

The opening area of the pipe 11 in the section on the YZ plane where the bulge 20 is formed is equal to the opening area in the section on the YZ plane where the bulge 20 is not formed. The opening on the right side of the vertical line passing through the lowest point 18 has a semicircular shape, and the area of the opening is equal to the area of the semicircle. The opening shape on the left side of the drawing from the vertical line passing through the lowest point 18 has a bulge 20 formed, and the vicinity of the most lateral point 19 bulges from the inner side to the outer side in the pipe radial direction. The opening area is equal to the opening area on the right side of the vertical line passing through the lowest point 18 in the figure.

As illustrated in FIG. 3, it is desirable that the inner peripheral surface of the pipe 11 on which the bulge 20 is formed is streamlined in the X direction. In the present disclosure, the streamlined shape indicates a shape in which the flow of fluid flowing in the X direction inside the pipe 11 is not blocked. The inner peripheral surface on which the bulge 20 of the present embodiment is formed has the shape of a spheroid divided in half, and slopes downward from the vertex 23 toward the terminal end 29 of the bulge 20 . The distance between the ends 29 of the bulge 20 on the XZ plane is longer than the diameter of the boss portion 12 , and the ends 29 are positioned outside the outer periphery of the boss portion 12 .

As described above, according to the piping structure 10 of the present disclosure, the lower portion of the pipe 11 and the tip portion of the boss portion 12 are integrated and overlapped, so that the pipe 11 and the boss portion 12 can be brought closer to each other. Therefore, interference with peripheral components can be avoided. Furthermore, according to the piping structure 10 of the present disclosure, the weir portion 21 that changes the shape of the pipe 11 and the detour portion 22 that does not change the shape, which are generated by bringing the pipe 11 and the boss portion 12 close to each other, are located at the bottom of the pipe 11. It exists with the point 18 as a boundary. Therefore, the fluid that tries to stay in the weir portion 21 flows into the detour portion 22 , so that it is possible to prevent the fluid from accumulating inside the pipe 11 .

The fluid will be explained as condensed water from recirculated exhaust. Condensed water, which is obtained by condensing water contained in the recirculated exhaust gas, flows toward the flow control valve 2 along the communication pipe 1 inclined downward, passes through the flow control valve 2, and flows into the bent pipe 16 and the pipe 11. The condensed water that has passed through the curved pipe 16 flows into the lowest point 18 of the pipe 11 avoiding the bulge 20 without being hindered even if it collides with the tip of the bulge 20 of the pipe 11.例文帳に追加In this way, since it is possible to avoid accumulation of condensed water, corrosion of the inside of the pipe 11 due to condensed water can be suppressed.

According to the piping structure 10, the piping 11 and the boss portion 12 are brought close to each other, and the piping 11 has a shape close to that of a cylindrical pipe. The target device can be installed in the middle of the piping. In this embodiment, the device intended for the shape of the cylindrical pipe is the flow control valve 2 with a built-in butterfly valve.

When the protruding length L1 is such that the tip 12a is arranged at a position not exceeding the lowest point 18, in order to secure a space for fastening the bolt 15, the lower part of the pipe 11 including the lowest point 18 is required. It is necessary to deform most of the inner peripheral surface upward. Therefore, the deformed portion acts as a weir against the upstream portion, and the condensed water flowing from the curved pipe 16 is accumulated. Further, when the protruding length L1 is such that the tip 12a is arranged at a position exceeding the sidemost point 19, the lengths of the bolt 15 and the boss portion 12 in the Y direction are extended. Therefore, the weight increases by the amount of extension. Further, the elongated boss portion becomes longer than the other boss portion 14 not integrated with the pipe 11, so that the common bolt 15 cannot be used for each of the boss portions 12 to 14. - 特許庁

Therefore, in the piping structure 10 of the present disclosure, the protruding length L1 of the boss portion 12 is set to a length such that the tip 12a exceeds the lowest point 18 and does not exceed the most lateral point 19 . As a result, it becomes possible to form the weir portion 21 and the detour portion 22 with the lowest point 18 as a boundary, thereby avoiding accumulation of condensed water as described above. Also, an increase in the weight of the piping structure 10 can be suppressed. In addition, a common bolt 15 can be used for each boss 12-14.

The protruding length L1 is the length at which the tip 12a is arranged at a position on the lowest point 18 side of the vertical line passing through the midpoint between the vertical line passing through the lowest point 18 and the vertical line passing through the most lateral point 19. more preferred. As a result, the lengths of the bolt 15 and the boss portion 12 are shortened, which is advantageous for weight reduction.

The inner peripheral surface of the pipe 11 on which the bulge 20 is formed preferably has a first slope 24 that slopes downward from the vertex 23 of the bulge 20 toward the terminal end 25 on the lowest point 18 side. As a result, when the piping structure 10 is manufactured by casting, the core stuffed inside the piping 11 can be easily taken out, and the manufacturing of the piping 11 having the bulge 20 is not troublesome, and the time required for the manufacturing is reduced. increase can be avoided. Similarly, the second slope 26 on the opposite side of the first slope 24 of the bulge 20 slopes downward from its terminal end toward the vertex 23, thereby facilitating removal of the core.

It is desirable that the terminal end 25 of the first slope 24 on the side of the lowest point 18 be positioned before the lowest point 18 . When the terminal end 25 of the first slope 24 is located before the lowest point 18 , the inner peripheral surface of the pipe 11 from the terminal end 25 to the lowest point 18 extends from the inner side to the outer side in the pipe radial direction similarly to the detour portion 22 . becomes a convex cylindrical surface. If the terminal end 25 is positioned at the lowest point 18 , the condensed water that has flowed into the pipe 11 may be blocked by the weir section 21 and may not flow into the detour section 22 . Therefore, by positioning the terminal end 25 before the lowest point 18 , it is possible to reliably flow the condensed water to the detour portion 22 . Since the terminal end 25 is positioned in front of the lowest point 18 on the YZ plane passing through the vertex 23 , the terminal ends 25 before and after the X direction are positioned further in front of the lowest point 18 .

It is desirable that the weir portion 21 has a slope that slopes downward toward the lowest point 18 over the entire inner peripheral surface of the pipe 11 . As a result, even if the condensed water collides vigorously with the tip of the bulge 20 and rides on the bulge 20, the condensed water that rides on the bulge 20 flows toward the lowest point 18 due to the slope. As a result, a state in which condensed water accumulates in the weir portion 21 can be avoided.

The inner peripheral surface of the pipe 11 on which the bulge 20 is formed is preferably streamlined in the X direction. The streamlined shape of the inwardly protruding portion allows the condensed water to flow smoothly and reduces resistance to the recirculated exhaust gas.

The contact of the flat surface 27 of the weir portion 21 with the bearing surface 15a of the bolt 15 means that the pipe 11 and the boss portion 12 are close to each other. By bringing the pipe 11 and the boss portion 12 close to each other so that the flat surface 27 constitutes a part of the tip 12a of the boss portion 12, the pipe structure 10 becomes compact.

Since the outer peripheral surface of the pipe 11 of the weir portion 21 does not interfere with the insertion and removal of the bolt 15 into and out of the boss portion 12, the tightening operation of the bolt 15 is avoided.

Although the embodiment of the present disclosure has been described above, the piping structure 10 of the present disclosure is not limited to a specific embodiment, and various modifications and changes are possible within the scope of the gist of the present disclosure.

The piping structure 10 of the present disclosure is not limited to piping in which the piping 11 constitutes a part of the exhaust gas recirculation passage, but can be applied to piping through which a fluid that causes corrosion of the inside of the piping 11 flows. . For example, an exhaust manifold is exemplified as such piping. It should be noted that the piping structure 10 is not limited to being mounted on an engine, and can be applied to other engines such as a boiler as long as the boss portion for attaching the piping to the wall surface is positioned below the piping. .

If the piping structure 10 is configured with a pipe 11 and a boss portion 12 arranged below this pipe 11,

other boss portions

13, 14, bent pipe 16, and flange 17 exemplified in the embodiment can be used. is not necessarily required. As long as the bolt 15 can be inserted into and removed from the boss portion 12, the shape of the outer circumference is not particularly limited. The axial direction of the bolt 15 inserted into and removed from the boss portion 12 is not limited to the direction perpendicular to the pipe axis direction of the pipe 11, and any direction that intersects the pipe axis direction can be applied.

In the piping structure 10, a portion of the upper portion of the piping 11 located directly below the tip of the boss portion 13 and the tip thereof are integrated and overlapped. In the piping structure 10 , the protrusion length of the boss portion 13 is the same as that of the boss portion 12 . In the piping structure 10, the upper part of the piping 11 has a portion where the pipe wall protrudes from the outer side to the inner side in the pipe radial direction and the pipe wall protrudes from the inner side to the outer side in the pipe radial direction. , and the arc-shaped portion of . In the piping structure 10 of the embodiment, the boss portion 13 arranged above the pipe 11 is also brought close to the pipe 11 like the boss portion 12 . By narrowing the space between the upper and

lower boss portions

12 and 13 of the pipe 11 in this way, it is advantageous to avoid the pipe structure 10 from interfering with other members. The bulge formed by integrating and overlapping the pipe 11 and the boss portion 13 does not accumulate condensed water, so the shape is not particularly limited.

The shape of the bulge 20 is limited to the shape of the embodiment as long as the tip disposed on the upstream side with respect to the flow of the fluid flowing through the pipe 11 does not block the fluid and the shape facilitates removal of the casting core. not something. For example, the shape of the bulge 20 is a semi-cylindrical shape in which the column axis direction is directed to the pipe axis direction, and the semicircular tip surface is inclined toward the lowest point 18 when viewed from the inside to the outside in the pipe radial direction. are exemplified. Also, the end of the bulge 20 does not collide with the fluid, and the shape of that portion is not particularly limited. The inner peripheral surface of the pipe 11 on which the bulge 20 is formed is desirably formed with a curved surface, but it does not have to be formed with a curved surface as long as the above conditions are satisfied.

This application is based on a Japanese patent application (Japanese Patent Application No. 2021-055577) filed on March 29, 2021, the contents of which are incorporated herein by reference.

The piping structure according to the present disclosure prevents fluid from accumulating inside while avoiding interference with surrounding components.

10 Piping structure 11 Piping 12-14 Boss portion 15 Bolt 17 Flange 20 Bulge 21 Weir portion 22 Detour portion 23 Vertex 24 First slope 25 End 26 Second slope 27 Flat surface 28 Curved surface

Claims

A pipe comprising a pipe arranged along a wall surface and a boss portion arranged below the pipe and protruding from the wall surface in a direction intersecting with the pipe axial direction of the pipe, into which a screw is inserted from the tip of the boss portion. in structure,
a portion of the lower portion of the pipe located directly above the tip of the boss portion and the tip of the pipe are integrated and overlapped;
The protrusion length from the wall surface to the tip of the boss portion exceeds the lowest point on the inner peripheral surface of the pipe where the tip is positioned directly above the boss portion and is the longest in the direction orthogonal to the lowest point. A length that is arranged at a position that does not exceed the most lateral point on the inner peripheral surface of the spaced pipe,
The lower portion of the pipe includes a weir portion having a bulging portion of the pipe wall that protrudes from the outer side to the inner side in the pipe radial direction, and an arc-shaped pipe wall that protrudes from the inner side to the outer side in the pipe radial direction. A piping structure characterized by lining up with a detour part forming a line.
The piping structure according to claim 1, wherein the inner peripheral surface of the pipe on which the bulge is formed has a first slope that slopes downward from the top of the bulge to the terminal end on the lowest point side.
The piping structure according to claim 2, wherein the terminal end of the first slope is arranged between the lowest points.
The pipe structure according to claim 2 or 3, wherein the weir part has a slope that slopes downward toward the lowest point over the entire inner peripheral surface of the pipe.
The pipe structure according to any one of claims 1 to 4, wherein the inner peripheral surface of the pipe on which the bulge is formed forms a streamlined shape in the direction of the pipe axis.
The dam portion has a flat surface perpendicular to the crossing direction on the outer peripheral surface of the pipe, and the flat surface constitutes a part of the tip of the boss portion, and the bearing surface of the screw abuts thereon. The piping structure according to any one of claims 1 to 5.
The pipe structure according to any one of claims 1 to 6, wherein the weir portion is configured such that the outer peripheral surface of the pipe does not interfere with the screw that is inserted into and removed from the boss portion.