JP2014196719A - Exhaust pipe for saddle riding type vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust pipe for a saddle riding type vehicle capable of easily ensuring excellence of exhaust discharge owing to pulsation effect and a reduction in ventilation resistance.SOLUTION: An exhaust pipe for a saddle riding type vehicle of a double pipe structure includes an inner pipe 21 to be built in an outer pipe 22 with a predetermined clearance interposed therebetween. The diameter of a downstream side end portion of the inner pipe 21 is enlarged, and the outer pipe 22 is formed longer by a predetermined length toward the downstream side than an enlarged diameter part 27 of the inner pipe 21. The diameter of an exhaust flow part for exhaust gas in the exhaust pipe is configured to be enlarged on the way.

Description

  The present invention relates to an exhaust pipe of a saddle type vehicle.

  An exhaust pipe having a double-pipe structure having an inner pipe and an outer pipe covering the inner pipe from the outside, the inner pipe being connected to the muffler, and the exhaust pipe passing through the inner pipe flows into the muffler Is conventionally known (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 7-189681

The output of the internal combustion engine changes depending on the characteristics of the exhaust pipe, and the characteristics of the exhaust pipe include a pulsation effect and ventilation resistance. Generally, the pulsation effect appears more effectively as the inner diameter of the exhaust pipe is smaller, and the effect is less likely to appear as it is larger.
On the other hand, the ventilation resistance becomes smaller as the inner diameter of the exhaust pipe becomes larger, and the desired pulsation effect may be difficult to appear. However, there is an advantage in that exhaust exhaust is improved.

  Here, the exhaust pipe disclosed in Patent Document 1 has a structure in which the inner diameter of the inner pipe is constant and is directly connected to the muffler, and the inner diameter of the inner pipe is constant, so that exhaust by reducing the pulsation effect and ventilation resistance. It is difficult to ensure one of the good omissions.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an exhaust pipe for a saddle-ride type vehicle that can easily ensure good exhaust loss due to reduced pulsation effect and ventilation resistance.

  As a means for solving the above-mentioned problems, the invention according to claim 1 is an exhaust pipe of a saddle-ride type vehicle having a double pipe structure having an inner pipe (21) that is installed in the outer pipe (22) through a required gap. The diameter of the downstream end of the inner tube (21) is increased, and the outer tube (22) is longer by a predetermined length than the diameter expanded portion (27) of the inner tube (21) toward the downstream side. It is formed, and the diameter of the exhaust circulation part of the exhaust in the exhaust pipe is increased in the middle.

  According to a second aspect of the present invention, a welding hole (28) is formed at a position facing the enlarged diameter portion (27) of the inner pipe (21) in the outer pipe (22), and the outer pipe (22) Welding is performed from the weld hole (28), and the enlarged diameter portion (27) is coupled to the inner peripheral surface of the outer tube (22), so that the downstream end of the inner tube (21) is the outer tube. (22).

  The invention according to claim 3 is characterized in that the enlarged diameter portion (27) is formed on the upper side and the lower side of the inner pipe (21) when mounted on a vehicle.

  According to a fourth aspect of the present invention, a muffler (15) is attached to the downstream end of the outer pipe (22), a catalyst (25) is attached in the muffler (15), and the outer pipe (22 ) Is bent from a position downstream of the downstream end of the inner pipe (21), and the downstream end of the outer pipe (22) is directed to the catalyst (25). It is characterized by.

  According to a fifth aspect of the present invention, the outer wall of the outer tube (22) has a recess (32) that is recessed toward the inner tube (21), and a bottom portion of the recess (32). A through hole (33) is formed in the collar, and a collar (31) for communicating the inside of the inner tube (21) and the outside of the outer tube (22) is inserted into the recess (32). (31) is welded to the peripheral portion of the through hole (33), and an oxygen sensor (30) for measuring the oxygen concentration in the exhaust pipe is attached to the exhaust pipe via the collar (31). To do.

  In the first aspect of the present invention, the exhaust flow part of the exhaust pipe enters the outer pipe from the downstream end of the inner pipe and expands the diameter, thereby reducing the ventilation resistance and improving the exhaust passage. It is possible to secure good exhaust evacuation while securing a desired pulsation effect by reducing the above. Here, the enlarged diameter portion of the exhaust circulation portion for reducing the airflow resistance is easily formed because it is formed by making the outer tube longer than the inner tube. For this reason, it is possible to easily ensure good exhaust passage due to the pulsation effect and the reduction in ventilation resistance.

  In invention of Claim 2, since the inner tube | pipe and outer tube | pipe which concern on this invention can be latched easily, productivity can be improved.

  According to the third aspect of the present invention, the welded portion or the like is located at a position that is difficult to see in appearance, and the appearance can be maintained.

  In the invention according to the fourth aspect, the exhaust gas that is expanded by expanding the diameter of the outer tube relative to the inner tube is discharged toward the catalyst, so that the exhaust gas can easily strike the catalyst evenly.

  In the invention according to claim 5, since the oxygen sensor is simply attached, productivity can be improved.

1 is a right side view of a main part of a motorcycle equipped with an exhaust pipe of a saddle-ride type vehicle according to an embodiment of the present invention. It is a right view of the said exhaust pipe and the muffler connected to this. It is a left view of the principal part of the said exhaust pipe and a muffler. It is an enlarged view of the joint part of the inner pipe and outer pipe in the exhaust pipe. It is sectional drawing in alignment with the exhaust pipe radial direction of the connection part of the inner pipe and outer pipe in the said exhaust pipe. It is the figure which showed the installation part of the oxygen sensor in the said exhaust pipe. It is sectional drawing in alignment with the exhaust pipe radial direction of the installation part of the oxygen sensor in the said exhaust pipe.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings used for the following description, the arrow FR indicates the front of the vehicle, and the arrow UP indicates the upper side of the vehicle.

FIG. 1 is a right side view of a main part of a motorcycle 1 equipped with an exhaust pipe of a saddle-ride type vehicle according to the present embodiment.
In the motorcycle 1, an engine 4 is disposed between a front wheel 2 and a rear wheel 3, and the engine 4 includes a crankcase 5 and a cylinder portion 6 erected upward from the upper front side of the crankcase 5, It has.

The body frame 7 of the motorcycle 1 includes a head pipe 8 located at the front end, a main frame 9 extending rearward from the head pipe 8, and extending downward from the head pipe 8, and a down frame 10 extending downward from the head pipe 8. .
In the engine 4, the rear portion of the crankcase 5 is supported by a pivot plate 11 provided at the lower end portion of the main frame 9, and the front portion of the crankcase 5 is supported by the lower end portion of the down frame 10.
A swing arm 12 extending rearward is supported on the pivot plate 11. The swing arm 12 is supported by the pivot plate 11 so that the front end of the swing arm 12 can swing in the vertical direction, and the rear wheel 3 at the rear of the swing arm 12 can swing.

  An intake system member 13 is connected to the rear part of the cylinder part 6, and an exhaust pipe 14 is connected to the front part of the cylinder part 6. Specifically, the cylinder portion 6 includes a cylinder block that is directly coupled to the crankcase, a cylinder head that is coupled to the cylinder block and has a combustion chamber formed therein, and a head cover that covers the cylinder head. The intake system member 13 and the exhaust pipe 14 are coupled to the cylinder head of the cylinder portion 6 and can communicate with the combustion chamber.

  The exhaust pipe 14 extends obliquely downward and forward from the front portion of the cylinder portion 6, then curves obliquely downward and rearward, and extends substantially straight rearward below the crankcase 5. Further, the exhaust pipe 14 changes its angle at a position on the outer side in the vehicle width direction of the front end of the rear wheel 3 and is bent obliquely rearward and upward, and a muffler 15 is connected to the rear end portion thereof. The muffler 15 extends obliquely rearward and upward from the rear end portion of the exhaust pipe 14 and is located on the outer side in the vehicle width direction of the rear wheel 3. The exhaust pipe 14 and the muffler 15 constitute an exhaust device for the motorcycle 1.

The exhaust pipe 14 is welded to a bracket 16 projecting upward from an outer peripheral portion of a portion extending in the front-rear direction below the crankcase 5, and the upper portion of the bracket 16 is fixed to the rear lower side of the crankcase 5. It is supported by the case 5.
The muffler 15 is supported by the frame member 18 by welding the bracket 17 to the front side and fixing the upper portion of the bracket 17 to the frame member 18 extending obliquely rearward and upward from the pivot plate 11.

FIG. 2 is a right side view of only the exhaust pipe 14 and the muffler 15, and the exhaust pipe 14 includes a connecting portion 20 with the cylinder portion 6, an inner pipe 21 extending from the connecting portion 20 and indicated by a broken line in the drawing, and a connecting portion. 20 and an outer tube 22 that covers the inner tube 21 from the outside with a required gap. In other words, the inner tube 21 is housed in the outer tube 22 through a required gap.
Exhaust gas flows from the cylinder portion 6 through the connecting portion 20 and the inner pipe 21 to the muffler 15 and is discharged from the muffler 15. Hereinafter, in the exhaust pipe 14, in the exhaust flow direction, the connecting portion 20 side is referred to as an upstream side, and the muffler 15 side is referred to as a downstream side. Also in the muffler 15, the exhaust inflow side is referred to as the upstream side, and the exhaust side is referred to as the downstream side.

The exhaust pipe 14 has a downstream end (not shown) of the outer pipe 22 inserted into an opening at the front end of the muffler 15, and the outer peripheral portion of the front end of the muffler 15 is tightened by a clamp 23, whereby the muffler 15 It is linked to.
In the present embodiment, the inner tube 21 and the outer tube 22 are pipe members having a circular cross section, and the inner diameters thereof are substantially constant from the upstream end to the downstream end. In addition, the direction orthogonal to the central axis of the inner tube 21 and the outer tube 22 is hereinafter referred to as a radial direction.

The muffler 15 communicates with the downstream end portion of the outer tube 22, and is connected to the downstream end portion of the outer tube 22 and the downstream end portion of the connecting tube 24 and extends rearward. The catalyst 25 is accommodated inside.
The connecting cylinder 24 is a member that receives the exhaust discharged from the rear end portion of the outer tube 22 and sends it to the catalyst 25, and is formed in a truncated cone shape that gradually increases in diameter toward the downstream side.
The catalyst 25 is formed in a cylindrical shape, purifies the exhaust gas that has passed through the connecting cylinder 24, and supplies it to the expansion chamber located behind the exhaust gas. Description of the configuration of the expansion chamber is omitted. Further, the outer diameter of the downstream end portion of the connecting cylinder 24 and the outer diameter of the upstream end portion of the catalyst 25 are substantially the same.

  FIG. 3 shows a left side view of the exhaust pipe 14. In the exhaust pipe 14, the outer pipe 22 is formed to be longer than the inner pipe 21 by a predetermined length toward the downstream side (rear side). The diameter of the exhaust gas distribution part from the part 20 to the muffler 15 is enlarged in the middle. That is, in the exhaust pipe 14, the downstream end portion of the outer tube 22 is positioned behind the downstream end portion of the inner tube 21, and the exhaust discharged from the downstream end portion of the inner tube 21 is exhausted from the outer tube 22. It expands in the downstream side end portion and flows to the muffler 15 side. In detail, the downstream end of the inner tube 21 is positioned away from the connection position (clamping position of the clamp 23) with the muffler 15 in the downstream portion of the outer tube 22 to the downstream side.

With reference to FIGS. 3 to 5, the downstream end of the inner tube 21 has a diameter-expanded portion 27 formed by partially expanding the diameter, and the diameter of the downstream end of the inner tube 21 is increased. Two portions 27 are formed so as to face each other across the central axis L1 (intake axis) of the inner pipe 21 (see FIG. 5).
On the other hand, a weld hole 28 is formed in each of the outer pipes 22 at a position facing the enlarged diameter portion 27 in the radial direction. A portion located radially outward in the enlarged diameter portion 27 is formed in an arc shape, and its curvature is substantially the same as that of the inner peripheral surface of the outer tube 22, and is located radially outward in the enlarged diameter portion 27. The portion to be in contact with the inner peripheral surface of the outer tube 22 by surface contact.

  And in this embodiment, it welds toward the inner side from the outer side of the welding hole 28, forms the welding bead 29 on the inner periphery and the enlarged diameter part 27 of the welding hole 28 so that these may be straddled, and an enlarged diameter part 27 is coupled to the inner peripheral surface of the downstream end of the outer tube 22, so that the downstream end of the inner tube 21 is coupled to the outer tube 22.

  Here, referring to FIG. 2, when the vehicle is mounted, in this exhaust pipe 14, the enlarged diameter portion 27 is formed so as to be positioned on the upper side and the lower side of the inner pipe 21. Accordingly, when the vehicle is mounted, the welding holes 28 are located on the upper side and the lower side of the outer tube 22 and are located at positions that are difficult to see in appearance.

  Further, referring to FIG. 3, the outer tube 22 is bent from a position downstream (backward) from the downstream end of the inner tube 21, and the downstream end of the outer tube 22 faces the catalyst 25. Yes.

That is, in FIG. 3, reference symbol C <b> 1 indicates the center point of the downstream portion of the outer tube 22 whose angle is changed with respect to the downstream end of the inner tube 21, and reference symbol L <b> 2 indicates the center of the downstream portion. The central axis of the downstream end portion of the outer tube 22 extending downstream through the point C1 and the center point of the downstream end portion of the outer tube 22 is shown.
Here, as is clear from the figure, the downstream side end portion of the outer tube 22 has its center axis L 2 aligned with the center axis of the catalyst 25. Therefore, the downstream end of the outer tube 22 is bent so as to be directed to the center of the catalyst 25.

  On the other hand, referring to FIGS. 2, 6, and 7, in this embodiment, an oxygen sensor 30 is provided at a site upstream of the exhaust pipe 14.

  A circular recess 32 that is recessed toward the inner tube 21 is formed on the outer wall of the upstream portion of the outer tube 22, and an outer tube-side through hole 33 is formed at the bottom of the recess 32. ing. In addition, an inner tube side through hole 34 having a smaller diameter than the outer through hole 33 is formed coaxially with the outer tube side through hole 33 at a portion located inside the outer tube side through hole 33 in the radial direction in the inner tube 21. Has been.

  A collar 31 that allows communication between the inside of the inner tube 21 and the outside of the outer tube 22 is inserted into the recess 32, and the collar 31 passes through the outer tube side through hole 33 and the inner tube side through hole 34 and passes through the collar 31. One end is fitted to the inner peripheral surface of the inner tube side through hole 34.

  In this embodiment, a weld bead 35 is formed across the outer peripheral surface of one end of the collar 31, the peripheral portion of the inner tube side through hole 34, and at least the inner peripheral surface of the outer tube side through hole 33. The oxygen sensor 30 is fixed to the other end of the collar 31 and attached to the exhaust pipe 14 via the collar 31.

  As described above, the exhaust pipe 14 of the present embodiment has a double pipe structure having the inner pipe 21 that is built in the outer pipe 22 via a required gap, and the downstream end portion of the inner pipe 21 is enlarged in diameter. Thus, the enlarged diameter portion 27 is formed, and the outer tube 22 is formed longer than the enlarged diameter portion 27 of the inner tube 21 toward the downstream side, and the diameter of the exhaust gas circulation portion of the exhaust tube 14 is increased. The diameter was expanded on the way.

  For this reason, since the exhaust circulation part of the exhaust pipe 14 enters the outer pipe from the downstream end of the inner pipe and expands the diameter from the middle, the ventilation resistance is reduced and the exhaust passage is improved, so the inner diameter of the inner pipe 21 is reduced. While ensuring the desired pulsation effect, it is possible to ensure good exhaust passage. Here, the enlarged diameter portion of the exhaust circulation portion for reducing the airflow resistance is easily formed because the outer tube 22 is formed longer than the inner tube 21. For this reason, according to the exhaust pipe 14 of the present embodiment, it is possible to easily ensure good exhaust passage due to a pulsation effect and a reduction in ventilation resistance.

Further, in the exhaust pipe 14 of the present embodiment, a weld hole 28 is formed at a position facing the enlarged diameter portion 27 of the inner pipe 21 in the outer pipe 22, and welding is performed from the weld hole 28 of the outer pipe 22 to increase the enlarged diameter portion. 27 is coupled to the inner peripheral surface of the outer tube 22 so that the downstream end of the inner tube 21 is coupled to the outer tube 22.
According to this, since the inner pipe 21 and the outer pipe 22 can be easily locked in the exhaust pipe 14, productivity can be improved.

  Further, in the exhaust pipe 14 of the embodiment, when the vehicle is mounted, the enlarged diameter portion 27 is formed so as to be positioned on the upper side and the lower side of the inner pipe 21, so that a welded portion or the like is difficult to see in the external view. Positioned and maintain good appearance.

Further, in the exhaust pipe 14 of the present embodiment, the muffler 15 is attached to the downstream end of the outer pipe 22, the catalyst 25 is attached to the muffler 15, and the outer pipe 22 is the downstream end of the inner pipe 21. It is bent from a position on the downstream side, and is formed so that the downstream end portion of the outer tube 22 faces the catalyst 25.
According to this, the exhaust gas expanded by the diameter expansion of the outer tube 22 with respect to the inner tube 21 is discharged toward the catalyst 25, so that the exhaust gas can easily strike the catalyst 25 evenly. Thereby, the catalyst 25 can be activated efficiently.

In the exhaust pipe 14 of the present embodiment, the outer wall of the outer tube 22 is formed with a recess 32 that is recessed toward the inner tube 21, and the outer tube side through hole 33 is formed at the bottom of the recess 32. The oxygen sensor 30 that is formed, the collar 31 is inserted into the recess 32, the collar 31 is welded to the peripheral portion of the outer tube side through hole 33, and the oxygen concentration in the exhaust pipe 14 is measured via the collar 31. It is attached to the exhaust pipe 14.
According to this, since the oxygen sensor 30 is easily attached, productivity can be improved.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above embodiment, the present invention is mounted on the motorcycle 1, but the vehicle is not limited to a motorcycle but may be a tricycle or a four-wheel vehicle. The engine is not limited to a single cylinder engine, and may be connected to a multi-cylinder engine.

Further, for example, in the above-described embodiment, the example in which the two enlarged diameter portions 27 are formed so as to face each other with the central axis L1 (intake axis) of the inner pipe 21 interposed therebetween is described. Good.
For example, when two enlarged diameter portions 27 are formed, one enlarged diameter portion 27 is formed in the semicircular region on one side of the inner tube 21 and one is formed on the other side. It does not have to be. Further, the number of the enlarged diameter portions 27 formed may be one or three or more.

  In addition, a protector may be provided on the outer peripheral portion of the downstream end portion of the outer tube 22 that is located downstream from the downstream end portion of the inner tube 21 and into which exhaust gas directly flows. In this case, the driver can be protected from the heat source, and appearance can be prevented from deteriorating due to the discoloration caused by heat.

  Moreover, in the said embodiment, although the exhaust pipe 14 is curved from the cylinder part 6 suitably and is extended toward back, the aspect of bending etc. is not limited to the said embodiment, In other aspects There may be.

1 Motorcycle (saddle-ride type vehicle)
14 Exhaust pipe 15 Muffler 21 Inner pipe 22 Outer pipe 25 Catalyst 27 Expanded part 28 Welding hole 30 Oxygen sensor 31 Collar 32 Recess 33 Outer pipe side through hole (through hole)

Claims (5)

In the exhaust pipe of a straddle-type vehicle having a double-pipe structure having an inner pipe (21) installed in the outer pipe (22) via a required gap,
The diameter of the downstream end of the inner pipe (21) is increased, and the outer pipe (22) is formed longer than the diameter enlarged portion (27) of the inner pipe (21) toward the downstream side. And
An exhaust pipe of a straddle-type vehicle, characterized in that a diameter of an exhaust circulation part of the exhaust in the exhaust pipe is increased in the middle. A welding hole (28) is formed at a position facing the enlarged diameter portion (27) of the inner pipe (21) in the outer pipe (22),
Welding is performed from the weld hole (28) of the outer pipe (22), and the enlarged-diameter portion (27) is coupled to the inner peripheral surface of the outer pipe (22), whereby the downstream of the inner pipe (21). The exhaust pipe of a saddle-ride type vehicle according to claim 1, wherein a side end portion is coupled to the outer pipe (22).   The exhaust of a straddle-type vehicle according to claim 2, wherein the enlarged-diameter portion (27) is formed so as to be positioned on an upper side and a lower side of the inner pipe (21) when mounted on the vehicle. tube. A muffler (15) is attached to the downstream end of the outer pipe (22),
A catalyst (25) is mounted in the muffler (15),
The outer pipe (22) is bent from a position downstream of the downstream end of the inner pipe (21), and the downstream end of the outer pipe (22) is directed toward the catalyst (25). The exhaust pipe of a straddle-type vehicle according to any one of claims 1 to 3, wherein the exhaust pipe is formed as follows. The outer wall of the outer tube (22) is formed with a recess (32) that is recessed toward the inner tube (21), and a through hole (33) is formed at the bottom of the recess (32). ,
A collar (31) for communicating the inside of the inner tube (21) and the outside of the outer tube (22) is inserted into the recess (32), and the collar (31) is inserted into the through hole (33). Welded to the periphery of
The saddle type according to any one of claims 1 to 4, wherein an oxygen sensor (30) for measuring an oxygen concentration in the exhaust pipe is attached to the exhaust pipe via the collar (31). Vehicle exhaust pipe.

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