JP7413333B2 - Internal combustion engine exhaust system - Google Patents

Description

The present invention relates to an exhaust system for an internal combustion engine.

Conventionally, in an exhaust system for an internal combustion engine, for example, Patent Document 1 discloses a pipe joint in the middle of an exhaust pipe. In this pipe joint, a fixed flange is provided at each end of a pair of pipes, and the fixed flanges are connected to each other with bolts. A second biasing means is provided between the fixed flanges to urge them apart, and the second biasing means is in airtight and slidable pressure contact with the facing surface of the fixed flange.

Japanese Patent Application Publication No. 2007-154960

By the way, when using springs in pipe joints as in the conventional structure mentioned above, consideration must be taken such as arranging multiple springs evenly around the exhaust pipe in order to suppress the inclination of the pipes and prevent exhaust leakage. However, there is a risk that the number of parts and the number of assembly steps will increase, leading to higher costs.

Therefore, the present invention can provide an exhaust system for an internal combustion engine that can prevent exhaust leakage from an exhaust pipe joint portion while having an inexpensive structure.

As a means for solving the above problem, the invention described in claim 1 provides an exhaust pipe ( 21), each of the pair of independent pipes (22) has a divided part (22d) in the pipe length direction, and the divided part (22d) has a divided upstream pipe (24) and a downstream pipe. (25) are provided along the outer peripheral surfaces of the upstream pipe (24) and the downstream pipe (25). an annular engaging portion (31, 32); and a holding member (37) that holds together the annular engaging portions (31, 32) of both the upstream pipe (24) and the downstream pipe (25). In one of the pair of independent pipes (22), one of the upstream pipe (24) and the downstream pipe (25) has the annular engaging portion (31, 32) in the pipe longitudinal direction with respect to the pipe body. Each of the upstream pipe (24) and the downstream pipe (25) connects the annular engaging portion (31, 32) to the other of the pair of independent pipes (22). The exhaust pipe (21) is fixed to the main body, and the exhaust pipe (21) has a connecting part that connects the pair of independent pipes (22) to each other near each divided part (22d) of the pair of independent pipes (22). (23a).
According to this configuration, by making the annular engagement portion of one of the upstream pipe and the downstream pipe slidable in one of the plurality of independent pipes, even if a difference in thermal expansion occurs between the plurality of independent pipes, , the difference in thermal expansion can be absorbed in one divided portion of the plurality of independent tubes. Since the slidable pipe connection structure only needs to be one of the plurality of independent pipes, an increase in the number of parts can be suppressed. That is, it is possible to reduce the number of parts and achieve an inexpensive structure, while preventing exhaust leakage from the divided portion due to the difference in thermal expansion between the plurality of independent pipes.
Further, by using only one of the upstream pipe and the downstream pipe as the slidable pipe connection structure, an increase in cost can be suppressed.
Further, by providing a connecting portion near each divided portion of the plurality of independent pipes, the rigidity of the entire exhaust pipe can be improved. Therefore, it is possible to suppress the relative positions of the plurality of independent pipes from shifting, and to create a structure in which exhaust leakage can be easily prevented.

In the invention described in claim 2, in one of the pair of independent pipes (22), the other of the upstream pipe (24) and the downstream pipe (25) has the annular engaging portion (31, 32). ) is fixed to the tube body.
According to this configuration, only one of the upstream pipe and the downstream pipe has a slidable pipe connection structure, thereby suppressing an increase in cost.

In the invention described in claim 3 , the exhaust pipe (21) includes a merging part (26) where the pair of independent pipes (22) merge with each other, and a collecting pipe (27) connected to the merging part (26). An exhaust valve device (29) is provided.
According to this configuration, even if the exhaust pipe internal pressure is likely to rise due to the operation of the exhaust valve device, exhaust leakage from the divided portion can be prevented.

In the invention described in claim 4 , the holding member (37) has an annular shape along the circumferential direction of the divided portion (22d), and the holding member (37) has an inner surface in a cross section perpendicular to the circumferential direction. A pair of tapered portions (38 a , 38b), and the annular engaging portions (31, 32) are inclined in a cross section perpendicular to the circumferential direction so that the outer circumferential side is located closer to the connecting partner tube in the axial direction, and 30) includes a gasket (35) sandwiched between the annular engaging portions (31, 32) of both the upstream pipe (24) and the downstream pipe (25), and the gasket (35) includes: By tightening the divided portion (22d) by the holding member (37), it is axially sandwiched between the annular engaging portions (31, 32) of both the upstream pipe (24) and the downstream pipe (25).
According to this configuration, the holding member only tightens the divided part by the tapered part of the holding member and the inclined annular engaging parts in the upstream pipe and the downstream pipe, and the gasket between both the annular engaging parts is moved in the axial direction. The structure can be compressed to prevent exhaust leakage. In addition, the gasket and the holding member can be made into a common component by a plurality of independent tubes, resulting in an inexpensive structure.

In the invention described in claim 5 , the upstream pipe (24) or the downstream pipe (25) that makes the annular engaging part (31, 32) slidable is the annular engaging part (31, 32). A regulating portion (39) is provided to regulate the amount of sliding.
According to this configuration, since the amount of sliding of the annular engaging part is regulated, large positional displacement of the annular engaging part is suppressed, the holding member can be assembled easily and reliably, and the structure is easily prevented from exhaust leakage. I can do it.

According to the present invention, it is possible to provide an exhaust system for an internal combustion engine that can prevent exhaust leakage from an exhaust pipe joint portion while having an inexpensive structure.

FIG. 1 is a left side view of a motorcycle in an embodiment of the present invention. FIG. 3 is a right side view of the exhaust system of the motorcycle. It is a top view of the said exhaust device. It is an exploded perspective view of the pipe connection structure of the above-mentioned exhaust device. It is a sectional view along the axial direction of the above-mentioned pipe connection structure.

Embodiments of the present invention will be described below with reference to the drawings. Note that the directions such as front, rear, left, and right in the following description are the same as the directions of the vehicle described below unless otherwise specified. In addition, arrow FR indicating the front of the vehicle, arrow LH indicating the left side of the vehicle, and arrow UP indicating the upward direction of the vehicle are shown at appropriate locations in the drawing used in the following explanation. The term "middle" used in this embodiment is intended to include not only the center between both ends of the object, but also the inner range between both ends of the object.

<Motorcycle>
As shown in FIG. 1, a motorcycle (saddle-type vehicle) 1 according to the embodiment includes a front wheel 2, a rear wheel 3, a front fork 4 that supports the front wheel 2, a swing arm 5 that supports the rear wheel 3, and a front fork 4 that supports the front wheel 2. The vehicle includes a body frame 6 that supports a front fork 4 and a swing arm 5, and an engine 7 (internal combustion engine, prime mover) supported by the body frame 6.

The engine 7 of the embodiment is a V-type four-cylinder engine in which the rotation center axis of the crankshaft is aligned in the vehicle width direction (left-right direction). The engine 7 includes a crankcase 10, a forward tilting cylinder 11, and a backward tilting cylinder 12. The forward tilting cylinder 11 stands up diagonally upward and forward, and the backward tilting cylinder 12 stands up diagonally upward and backward.

An intake port and an exhaust port (not shown) are formed at the front and rear of the cylinder heads of the front and rear cylinders 11 and 12, respectively. Specifically, a pair of intake ports corresponding to a pair of left and right cylinders are formed at the rear of the forward-tilting cylinder 11, and a pair of exhaust ports corresponding to a pair of left and right cylinders are formed at the front of the forward-tilting cylinder 11. It is formed. A pair of intake ports corresponding to the pair of left and right cylinders are formed at the front of the backward-tilting cylinder 12, and a pair of exhaust ports corresponding to the pair of left and right cylinders are formed at the rear of the rear-tilting cylinder 12. . An intake device is connected to each intake port of the front and rear cylinders 11 and 12, and an exhaust device is connected to each exhaust port of the front and rear cylinders 11 and 12.

<Exhaust device>
The exhaust system includes an exhaust pipe including an independent upstream portion for each pair of left and right cylinders in the front and rear cylinders 11 and 12.
The exhaust pipe of the exhaust system of the forward-tilting cylinder 11 is appropriately curved in front of the cylinder, turned back and extended to the rear, and is connected to a muffler (not shown) disposed at the lower part of the vehicle body.
The exhaust pipe of the rearward-inclined cylinder 12 extends in an appropriately curved manner toward the rear of the cylinder, and is connected to a muffler disposed above the rear wheel 3 .

The exhaust device 20 for the backward tilting cylinder 12 will be described below with reference to FIGS. 2 and 3. Note that the following configuration can also be applied to the exhaust device of the forward-inclined cylinder 11.
The exhaust pipe 21 of the exhaust system 20 constitutes an upstream part of the exhaust pipe 21, and includes a pair of independent pipes 22 provided corresponding to a pair of left and right cylinders in the backward-inclined cylinder 12, and a downstream end of the pair of independent pipes 22. A single collecting pipe 27 that extends downstream (backwards) of the joining part 26 and a downstream end (rear end) of the collecting pipe 27 are connected to each other. A muffler 28 is provided.

Upstream ends 22a (front ends) of the pair of independent pipes 22 are respectively connected to the openings of the exhaust ports of the respective cylinders on the rear wall of the backward-inclined cylinder 12. The upstream end 22a of each independent tube 22 is provided with a fastening flange 22b around the opening of each exhaust port. A first connecting portion 23a and a second connecting portion 23b that connect the pair of independent tubes 22 are provided at an intermediate portion in the length direction (tube length direction) of the pair of independent tubes 22. The first connecting portion 23a and the second connecting portion 23b are spaced apart from each other in the length direction of each independent tube 22. The first connecting portion 23a on the cylinder 12 side is made of, for example, a solid connecting member. The second connecting portion 23b on the muffler 28 side is formed of, for example, a hollow connecting pipe, and allows the flow paths of the pair of independent pipes 22 to communicate with each other.

The independent pipes 22 extend rearward while being appropriately bent to adjust the pipe length behind the backward tilting cylinder 12, and after merging with each other at a merging portion 26 located above the rear wheel 3, are connected to a collecting pipe 27. At the rear of each independent pipe 22, a catalyst 22c is provided in a predetermined length range in front of the merging portion 26.

The collecting pipe 27 has a shorter pipe length than each of the independent pipes 22, and extends rearward above the rear wheel 3 in a slightly upwardly rearward direction. The collecting pipe 27 is provided with an exhaust valve device 29 .
A front end of a muffler 28 is connected to a rear end of the collecting pipe 27 . The muffler 28 extends rearward so as to be continuous with the collecting pipe 27, and has a rear end opening 28a (exhaust port) opening toward the rear of the vehicle at the upper rear end of the vehicle body.

The exhaust valve device 29 changes the flow path area within the exhaust pipe 21 (collecting pipe 27). The exhaust valve device 29 includes a valve body (not shown) disposed within the collecting pipe 27. The valve body has a drive shaft 29a that passes through the collecting pipe 27 in the radial direction, and a drive pulley 29b is attached to the end of the drive shaft 29a.A drive cable extending from an actuator (not shown) is connected to the drive pulley 29b. 29c is connected.

Each independent tube 22 has a portion of a predetermined tube length extending rearward from the front end and is configured as an upstream tube 24 separately from a downstream portion. Each upstream pipe 24 is attachable to and detachable from a portion rearward (downstream) of itself. Hereinafter, a portion of each independent pipe 22 that is rearward (downstream) of the upstream pipe 24 will be referred to as a downstream pipe 25. Reference numeral 22d in the figure indicates a dividing portion between the upstream pipe 24 and the downstream pipe 25.

The front end of each independent pipe 22 (the front end of each upstream pipe 24) is fixed to the backward tilting cylinder 12 by a fastening flange 22b. The rear end of each upstream pipe 24 is connected to the front end of each downstream pipe 25, respectively.
The left and right cylinders in the backward-inclined cylinder 12 that are parallel to each other have the same thermal environment in their combustion chambers. The independent pipes 22 connected to each cylinder have the same length and are designed to cause the same thermal expansion.

<Pipe connection structure>
At the dividing portion 22d between the upstream pipe 24 and the downstream pipe 25, the upstream pipe 24 and the downstream pipe 25 are connected to each other by a pipe connection structure 30.
4 and 5, the pipe connection structure 30 includes a first annular engagement portion 31 provided along the outer circumference of the upstream pipe 24 and a second annular engagement portion provided along the outer circumference of the downstream pipe 25. A gasket 35 sandwiched between the joint part 32, the first annular engaging part 31 and the second annular engaging part 32, and a holding part that holds the first annular engaging part 31 and the second annular engaging part 32 together. A member 37 is provided.

The first annular engaging portion 31 is disposed at a position shifted forward from the rear end of the upstream pipe 24 by a predetermined amount. The first annular engaging portion 31 is a tapered flange that is inclined so as to be located toward the rear (downstream pipe 25 side) toward the outer circumference. A portion rearward of the first annular engagement portion 31 (rear end portion of the upstream tube 24 ) is a cylindrical insertion portion 33 that can be inserted into the front end portion of the downstream tube 25 .
The second annular engagement portion 32 is arranged so as to rise from the front end of the downstream pipe 25 toward the outer circumference. The second annular engaging portion 32 is a tapered flange that is inclined so that the outer circumferential side is located further forward (upstream pipe 24 side).

The angle of the first annular engaging portion 31 with respect to the outer peripheral surface of the upstream pipe 24 and the angle of the second annular engaging portion 32 with respect to the outer peripheral surface of the downstream pipe 25 are the same. What is the standing height (length) of the first annular engaging portion 31 from the outer peripheral surface of the upstream pipe 24 and the standing height (length) of the second annular engaging portion 32 from the outer peripheral surface of the downstream pipe 25? , are considered to be identical to each other.

The gasket 35 has an annular shape and is attached to the outer periphery of the insertion portion 33 of the upstream pipe 24 . Hereinafter, a cross section of the gasket 35 perpendicular to the circumferential direction will be described with reference to a cross-sectional view of the figure. In a cross section perpendicular to the circumferential direction of the gasket 35, the cross-sectional shape of the gasket 35 is approximately trapezoidal. The inner circumferential surface 35a of the gasket 35 is formed so as to be in surface contact with the outer circumferential surface 33a of the insertion portion 33. A front surface 35 b along the inclined side on the upstream pipe 24 side in the cross-sectional shape of the gasket 35 is formed so as to come into surface contact with the rear surface 31 a of the first annular engagement portion 31 of the upstream pipe 24 . A rear surface 35c along the inclined side on the downstream pipe 25 side in the cross-sectional shape of the gasket 35 is formed so as to be in surface contact with the front surface 32a of the second annular engagement portion 32 of the downstream pipe 25.

The holding member 37 functions as a band that tightens the first annular engaging portion 31, the second annular engaging portion 32, and the gasket 35 from the outer circumferential side. The holding member 37 has an annular shape along the circumferential direction of the divided portion 22d. The holding member 37 has a configuration in which, for example, an annular body is divided into halves and the divided bodies are connected to each other by a hinge 37a. The holding member 37 can be secured to the first annular engaging portion 31 and the second annular engaging portion 32 by tightening a tightening portion 37b provided on the opposite side in the radial direction from the hinge 37a with a bolt 37c along the tangential direction. Then, tighten the gasket 35 from the outer circumferential side.

The holding member 37 has a U-shaped cross section that opens toward the inner circumference in a cross section perpendicular to the circumferential direction. A pair of tapered portions 38a and 38b are provided on both sides of the cross-sectional shape of the holding member 37 in the axial direction, and the tapered portions 38a and 38b are inclined so as to open outward in the axial direction toward the inner circumference. Hereinafter, the tapered part 38a on the front side (upstream pipe 24 side) will be referred to as a first taper part 38a, and the tapered part 38b on the rear side (downstream pipe 25 side) will be referred to as a second taper part 38b.

To assemble the exhaust pipe 21, first attach the gasket 35 to the front part of the insertion part 33 of the upstream pipe 24, insert the rear part of the insertion part 33 into the front end of the downstream pipe 25, and then connect the first annular engaging part 31 and the first annular engaging part 31 to the front end of the downstream pipe 25. A gasket 35 is sandwiched between the two annular engaging portions 32. In this state, the holding member 37 is attached so as to cover the first annular engaging portion 31, the second annular engaging portion 32, and the gasket 35 together from the outer circumferential side. The holding member 37 is in a state separated from the outer peripheral surfaces of the upstream pipe 24 and the downstream pipe 25 before the gasket 35 is crushed. Further, the inner surfaces of the first tapered portion 38a and the second tapered portion 38b of the holding member 37 are in contact with the front surface of the first annular engagement portion 31 and the rear surface of the second annular engagement portion 32, respectively.

By tightening the bolt 37c of the holding member 37 from this state, the inner surfaces of the first tapered portion 38a and the second tapered portion 38b of the holding member 37 are connected to the front surface of the first annular engagement portion 31 and the second annular engagement portion. The first annular engaging portion 31 and the second annular engaging portion 32 approach each other along the rear surface of the portion 32 . As a result, the gasket 35 is compressed and crushed in the axial direction between the first annular engaging part 31 and the second annular engaging part 32, and the gasket 35 is also pressed against the outer peripheral surface 33a of the insertion part 33. be crushed. By tightening the holding member 37, the gasket 35 is crushed, thereby preventing exhaust leakage from the divided portion 22d of each independent pipe 22.

The exhaust device 20 includes a first annular engaging portion 31 of one of the upstream pipe 24 and the downstream pipe 25 (the upstream pipe 24 in the embodiment) in one of the plurality of independent pipes 22 (on the near side in the figure, on the lower side in the figure). is slidable in the pipe length direction with respect to the cylindrical main body (pipe main body) of the upstream pipe 24. The first slidable annular engagement portion 31 is bent and stands up from one axial end of the cylindrical portion 31b that fits onto the upstream pipe 24 . The first annular engaging portion 31 and the cylindrical portion 31b are configured as a collar member 31c (slide collar) separate from the upstream pipe 24.

By providing the slidable annular engagement portion (collar member 31c), even if a difference in thermal expansion occurs between the plurality of independent pipes 22 in the pipe length direction during operation of the engine 7, this difference in thermal expansion can be reduced between the plurality of independent pipes 22. It becomes possible to absorb the water at one divided portion 22d of the independent tube 22. The upstream pipe 24 and the downstream pipe 25 of the independent pipe 22 are made of different metal materials, and therefore have different coefficients of thermal expansion. Further, the upstream pipe 24 and the downstream pipe 25 have different distances from the exhaust port, and also have different coefficients of thermal expansion in this respect.

The slidable annular engagement portion (collar member 31c) may be provided on both upstream pipes 24 of the plurality of independent pipes 22. Furthermore, the collar member 31c may be provided not only in the upstream pipe 24 but also in the downstream pipe 25. In the embodiment, among the four annular engaging portions 31 and 32 of each upstream pipe 24 and each downstream pipe 25 of a pair of independent pipes 22, the one independent pipe 22 that had the largest thermal effect in actual measurements was A movable annular engagement portion (collar member 31c) is provided.

The more locations the collar member 31c is provided, the more parts the exhaust device 20 will have, the more likely the axial position of the pipe connection structure 30 will shift, and the greater the risk of exhaust leaking from the sliding portion of the collar member 31c. do. For this reason, as in the embodiment, it is preferable that the collar member 31c is provided at one location, and the annular engaging portions 31 and 32 at other locations are fixed to the exhaust pipe 21. "Fixing the annular engagement part" means fixing the annular engagement part immovably to the pipe body of the target upstream pipe 24 or downstream pipe 25 by welding, etc., or fixing the annular engagement part integrally with the pipe body. Also includes.

In addition, "slidable" in the embodiment means that it is movable by a predetermined or more axial load, for example, even when the holding member 37 is fastened. For example, the fitting between the collar member 31c and the upstream pipe 24 may be a loose fit before the holding member 37 is fastened, and when the holding member 37 is fastened, the collar member 31c may come into pressure contact with the upstream pipe 24 and become slidable. Alternatively, the fitting between the collar member 31c and the upstream pipe 24 may be a tight fit before the holding member 37 is fastened, and the collar member 31c may be configured to be slidable with respect to the upstream pipe 24.

A regulating portion 39 that protrudes toward the outer circumferential side of the outer circumferential surface 33a of the insertion portion 33 is provided at a portion of the upstream pipe 24 in front of the collar member 31c. The regulating portion 39 is, for example, an annular convex portion along the outer circumferential surface 33a of the insertion portion 33, and regulates the amount of forward movement of the collar member 31c.

As described above, the exhaust system for an internal combustion engine in the above embodiment includes an exhaust pipe 21 including a plurality of independent pipes 22 that each independently guide exhaust gas from a plurality of cylinders arranged in parallel with each other in the engine 7. Each of the plurality of independent pipes 22 has a divided part 22d in the pipe length direction, and the divided part 22d is provided with a pipe connection structure 30 that connects the divided upstream pipe 24 and downstream pipe 25 to each other in a detachable manner. The pipe connection structure 30 includes annular engagement parts 31 and 32 provided along the outer peripheral surfaces of the upstream pipe 24 and the downstream pipe 25, and annular engagement parts 31 and 32 provided along the outer circumferential surfaces of the upstream pipe 24 and the downstream pipe 25, and the annular engagement parts of both the upstream pipe 24 and the downstream pipe 25. a holding member 37 that holds the joining parts 31 and 32 together, and in one of the plurality of independent pipes 22, one of the upstream pipe 24 and the downstream pipe 25 holds the annular engaging part 31 together with the pipe main body. It is possible to slide in the longitudinal direction of the pipe.

According to this configuration, by making the annular engagement portion 31 of one of the upstream pipe 24 and the downstream pipe 25 slidable in one of the plurality of independent pipes 22, the thermal expansion difference between the plurality of independent pipes 22 is increased. Even if this occurs, the difference in thermal expansion can be absorbed in one divided portion 22d of the plurality of independent tubes 22. Since the slidable tube connection structure 30 only needs to be one of the plurality of independent tubes 22, an increase in the number of parts can be suppressed. That is, it is possible to reduce the number of parts and achieve an inexpensive structure, while preventing exhaust leakage from the divided portion 22d due to the difference in thermal expansion between the plurality of independent pipes 22.

Further, in the exhaust system for an internal combustion engine, in one of the plurality of independent pipes 22, the other of the upstream pipe 24 and the downstream pipe 25 has the annular engaging portion 32 fixed to the pipe body. ing.
According to this configuration, since the slidable pipe connection structure 30 is provided only in one of the upstream pipe and the downstream pipe, it is possible to suppress an increase in cost.

Further, in the exhaust system for an internal combustion engine, each of the upstream pipe 24 and the downstream pipe 25 has the annular engaging portions 31 and 32 relative to the pipe main body in the other of the plurality of independent pipes 22. Fixed.
According to this configuration, the slidable pipe connection structure 30 is provided in one of the plurality of independent pipes 22 and only in one of the upstream pipe and the downstream pipe, thereby making it possible to suppress an increase in cost.

Further, in the exhaust system for an internal combustion engine, the exhaust pipe 21 includes a merging section 26 where the plurality of independent pipes 22 merge with each other, and an exhaust valve device 29 provided in a collecting pipe 27 connected to the merging section 26. We are prepared.
According to this configuration, even if the internal pressure of the exhaust pipe 21 is likely to increase due to the operation of the exhaust valve device 29, exhaust leakage from the divided portion 22d can be prevented.

Furthermore, in the exhaust system for an internal combustion engine, the exhaust pipe 21 is provided with a connecting portion 23a that connects the plurality of independent pipes 22 to each other in the vicinity of each dividing portion 22d of the plurality of independent pipes 22.
According to this configuration, the rigidity of the exhaust pipe 21 as a whole can be improved by providing the connecting portion 23a near each divided portion 22d of the plurality of independent pipes 22. Therefore, it is possible to suppress the relative positions of the plurality of independent pipes 22 from shifting, and to create a structure in which exhaust leakage can be easily prevented.

Further, in the exhaust system for an internal combustion engine, the holding member 37 has an annular shape along the circumferential direction of the divided portion 22d, and the holding member 37 is open to the inner circumferential side in a cross section perpendicular to the circumferential direction. It has a U-shaped cross-sectional shape, and is provided with a pair of tapered portions 38a and 38b on both sides of the cross-sectional shape in the axial direction, forming inner surfaces that are inclined such that the inner circumferential side opens outward in the axial direction. In a cross section orthogonal to the circumferential direction, the annular engaging portions 31 and 32 are inclined so that the outer circumferential side is located closer to the connecting partner pipe in the axial direction, and the pipe connecting structure 30 A gasket 35 is provided which is held between both the annular engaging parts 31 and 32 of the pipe 25, and the gasket 35 is secured to the upstream pipe 24 and the downstream pipe by tightening the dividing part 22d by the holding member 37. 25 is sandwiched between the annular engaging portions 31 and 32 in the axial direction.
According to this configuration, the holding member 37 only tightens the divided portion 22d by the tapered portions 38a, 38b of the holding member 37 and the inclined annular engaging portions 31, 32 in the upstream pipe 24 and the downstream pipe 25, and both The gasket 35 between the annular engaging portions 31 and 32 can be compressed in the axial direction to prevent exhaust leakage. Moreover, the gasket 35 and the holding member 37 can be made into a common part by a plurality of independent tubes 22, and an inexpensive structure can be achieved.

Further, in the exhaust system for an internal combustion engine, the upstream pipe 24 that allows the annular engaging portion 31 to slide is provided with a regulating portion 39 that restricts the amount of sliding of the annular engaging portion 31 .
According to this configuration, since the amount of sliding of the annular engaging part 31 is regulated, large displacement of the annular engaging part 31 is suppressed, the holding member 37 can be easily and reliably assembled, and the structure facilitates preventing exhaust leakage. It can be done.

Note that the present invention is not limited to the above-described embodiments; for example, in the above-described embodiments, the present invention is applied to a V-type four-cylinder engine, but the scope of application of the present invention is not limited thereto. That is, the present invention may be applied to various internal combustion engines having an exhaust system. Further, the present invention may be applied to an internal combustion engine with a separate transmission.
The internal combustion engine of this embodiment may be applied to saddle-ride type vehicles other than motorcycles. The saddle-riding type vehicle includes all types of vehicles in which the driver rides astride the body of the vehicle, and includes not only motorcycles (including motorized bicycles and scooter-type vehicles) but also three-wheeled vehicles (including one front wheel and two rear wheels). , vehicles with two wheels in the front and one wheel in the rear) or vehicles with four wheels (four-wheel buggy, etc.) are also included.
The present invention may be applied to a vehicle that includes an electric motor as a prime mover. Furthermore, the present invention may be applied to vehicles other than saddle-ride vehicles (passenger cars, buses, trucks, etc.).
Furthermore, although the internal combustion engine of this embodiment is applied to a vehicle, the present invention is not limited to application to vehicles, and can be applied to various transportation equipment such as aircraft and ships, as well as various vehicles such as construction machinery and industrial machinery. It may also be applied to mobile objects. Furthermore, the present invention is widely applicable to devices other than vehicles that include an internal combustion engine, such as hand-operated lawn mowers and cleaning machines.
The configuration in the embodiment described above is an example of the present invention, and various changes can be made without departing from the gist of the present invention, such as replacing the constituent elements of the embodiment with well-known constituent elements.

1 Motorcycle (saddle type vehicle)
7 Engine (internal combustion engine)
20 Exhaust device 21 Exhaust pipe 22 Independent pipe 22d Divided part 23a Connection part 24 Upstream pipe 25 Downstream pipe 26 Merging part 27 Collecting pipe 29 Exhaust valve device 30 Pipe connection structure 31 First annular engaging part (annular engaging part)
32 Second annular engagement part (annular engagement part)
35 Gasket 37 Holding member 38a First tapered part (tapered part)
38b Second tapered part (tapered part)
39 Regulatory Department

Claims (5)

An exhaust pipe (21) including a pair of independent pipes (22) each independently guiding exhaust from a pair of cylinders arranged in parallel with each other in an internal combustion engine (7),
Each of the pair of independent pipes (22) has a divided part (22d) in the pipe length direction, and the divided part (22d) has a divided upstream pipe (24) and a downstream pipe (25) connected to each other. A pipe connection structure (30) for removably connecting is provided,
The pipe connection structure (30) includes annular engaging portions (31, 32) provided along the outer peripheral surfaces of the upstream pipe (24) and the downstream pipe (25), and a holding member (37) that holds both the annular engaging portions (31, 32) of the tube (25) together;
In one of the pair of independent pipes (22), one of the upstream pipe (24) and the downstream pipe (25) slides the annular engaging portion (31, 32) relative to the pipe body in the pipe length direction. It is possible ,
In the pair of independent tubes (22), each of the upstream tube (24) and the downstream tube (25) has the annular engaging portion (31, 32) fixed to the tube body. and
The exhaust pipe (21) is equipped with a connecting part (23a) that connects the pair of independent pipes (22) to each other in the vicinity of each divided part (22d) of the pair of independent pipes (22). Engine exhaust system. In one of the pair of independent pipes (22), the other of the upstream pipe (24) and the downstream pipe (25) fixes the annular engaging portion (31, 32) to the pipe body. The exhaust system for an internal combustion engine according to claim 1. The exhaust pipe (21) is
a merging portion (26) where the pair of independent pipes (22) merge with each other;
The exhaust system for an internal combustion engine according to claim 1 or 2 , further comprising an exhaust valve device (29) provided in a collecting pipe (27) connected to the merging section (26). The holding member (37) is annular along the circumferential direction of the divided portion (22d),
The holding member (37) has a U-shaped cross-sectional shape that opens toward the inner circumferential side in a cross section perpendicular to the circumferential direction, and has a U-shaped cross-sectional shape that opens toward the inner circumferential side, and has a U-shaped cross-sectional shape that opens toward the inner circumferential side on both sides of the cross-sectional shape in the axial direction. A pair of tapered portions (38a, 38b) forming an inner surface that slopes outward,
The annular engaging portion (31, 32) is inclined in a cross section perpendicular to the circumferential direction so that the outer circumferential side is located closer to the connecting partner pipe in the axial direction,
The pipe connection structure (30) includes a gasket (35) held between the annular engaging portions (31, 32) of both the upstream pipe (24) and the downstream pipe (25),
The gasket (35) locks the annular engaging portions (31, 32) of both the upstream pipe (24) and the downstream pipe (25) by tightening the divided portion (22d) with the holding member (37). The exhaust system for an internal combustion engine according to any one of claims 1 to 3 , wherein the exhaust system is axially sandwiched between the exhaust system. The upstream pipe (24) or the downstream pipe (25) that allows the annular engaging part (31, 32) to slide has a regulating part (24) that regulates the amount of sliding of the annular engaging part (31, 32). 39). The exhaust system for an internal combustion engine according to any one of claims 1 to 4 .

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