WO2018061120A1

WO2018061120A1 - Exhaust device for saddled vehicle

Info

Publication number: WO2018061120A1
Application number: PCT/JP2016/078697
Authority: WO
Inventors: 亮輔木下; 加藤　達朗; 智則難波; 貞隆岡部; 和朗古川
Original assignee: 本田技研工業株式会社
Priority date: 2016-09-28
Filing date: 2016-09-28
Publication date: 2018-04-05
Also published as: JPWO2018061120A1; TW201819754A; TWI647382B; JP6720326B2; DE112016007276T5

Abstract

Provided is an exhaust device for a saddled vehicle, the exhaust device being configured such that, even if an exhaust pipe which has a catalyst containing pipe provided at the downstream end thereof is mounted at an angle of tilt relative to the front-rear direction of the vehicle in a plan view of the vehicle, sharp bending of the exhaust pipe near upstream of a section connected to an exhaust muffler is suppressed, and the capacity of the expansion chamber of the exhaust muffler is not sacrificed. This exhaust device for a saddled vehicle is provided with: an exhaust pipe 50 having an upstream end connected to an internal combustion engine 3; and an exhaust muffler 70 to which a catalyst containing pipe 60 interconnected in the direction in which the downstream end 50b of the exhaust pipe extends is connected, the exhaust muffler having an expansion chamber 90 provided therein. The connection surface 74A of the exhaust muffler, the connection surface 74A having connected thereto the catalyst containing pipe and facing the front of the vehicle, is disposed so as to extend in the left-right direction y-y of the vehicle, the catalyst containing pipe interconnected with the exhaust pipe is connected to the connection surface at a tilt angle θ relative to the front-rear direction x-x of the vehicle in a plan view of the vehicle, and, at the position where the catalyst containing pipe is connected to the connection surface, a part of the catalyst containing pipe is disposed extending into the expansion chamber.

Description

Exhaust system for straddle-type vehicles

The present invention relates to an exhaust system for a straddle-type vehicle provided with a catalyst internal pipe at the downstream end of an exhaust pipe and an exhaust muffler.

An arrangement in which a partition wall is disposed in the internal space of the exhaust muffler and the internal space is divided into a plurality of expansion chambers is shown, for example, in Patent Document 1 below. In the exhaust muffler shown in Patent Document 1, an exhaust pipe for introducing exhaust gas from an internal combustion engine to the exhaust muffler is vertically connected from the front to a connecting surface extending in the vehicle left-right direction in the exhaust muffler. The entire catalyst internal pipe continuously provided in the extending direction of the downstream end of the exhaust pipe is accommodated inside the exhaust muffler.
The exhaust muffler needs to secure the capacity of the expansion chamber in order to satisfy the muffling function, but in the case shown in Patent Document 1, the volume occupied by the catalyst internal pipe inside the exhaust muffler becomes large, and the expansion chamber There were problems in securing the capacity of
On the other hand, Patent Document 2 below shows that the exhaust pipe is vertically connected from the front to the connecting surface of the exhaust muffler extending in the lateral direction of the vehicle in plan view of the vehicle. Because it is biased, it forms a sharp bend and connects to the connecting surface of the exhaust muffler.
Although it is desirable to connect the exhaust pipe vertically to the connecting surface of the exhaust muffler, there has been a problem that an exhaust pipe shape having a sharp bend may affect the output.
Further, when the downstream end of the exhaust pipe has to be curved in the longitudinal direction of the vehicle due to the layout of the vehicle, if the connecting surface of the exhaust muffler is formed perpendicular to the exhaust pipe, the connecting surface of the exhaust muffler becomes the vehicle It inclines and retreats to the horizontal direction, and the capacity of the expansion chamber decreases accordingly.

Patent No. 5469821 (FIGS. 1, 3, 5, 7) JP, 2014-234750, A (Drawing 1-3)

The present invention has been made in view of the above-mentioned prior art, and in an exhaust system provided with a catalyst internal pipe at the downstream end of the exhaust pipe, the exhaust pipe is directed to the longitudinal direction of the vehicle in a plan view of the vehicle Even in the case of having an inclination angle, the sudden bending of the exhaust pipe in the vicinity of the connection portion with the exhaust muffler is suppressed, and the exhaust capacity of the expansion chamber of the exhaust muffler can be avoided from being sacrificed It aims at providing an apparatus.

In order to achieve the above object, the present invention provides an exhaust pipe in which a power unit including an internal combustion engine is mounted on a straddle-type vehicle, and an upstream end is connected to the internal combustion engine to form an exhaust gas passage for discharging exhaust gas. And an exhaust muffler connected to a downstream end of the exhaust pipe connected to a catalyst internal pipe continuously provided in the extending direction, and an exhaust system of a straddle-type vehicle having an expansion chamber in an internal space of the exhaust muffler. ,
The exhaust muffler is configured such that the outer shell is constituted by a plurality of types of construction surfaces, and the construction surface facing the front of the vehicle is connected as the connection surface and extends in the vehicle lateral direction. The catalyst internal pipe continuously connected to the pipe is connected to the connecting surface with an inclination angle with respect to the longitudinal direction of the vehicle in plan view of the vehicle, and the catalyst internal pipe is connected to the connecting surface at the same position. According to another aspect of the present invention, there is provided an exhaust system for a straddle-type vehicle, wherein a portion of a catalyst internal pipe is disposed across the expansion chamber.
According to the above configuration, the exhaust pipe has an inclination angle with respect to the longitudinal direction of the vehicle in a plan view of the vehicle and is connected to the connecting surface of the exhaust muffler disposed so as to extend in the lateral direction of the vehicle. When the exhaust pipe is connected, the catalyst internal pipe continuously provided in the extension direction of the downstream end of the exhaust pipe protrudes upstream from the connection surface and a part is disposed across the expansion chamber, and in plan view of the vehicle By being connected to the connecting surface with an inclination angle with respect to the longitudinal direction of the vehicle, a sharp curve of the exhaust pipe near the upstream side of the catalyst internal pipe can be suppressed.
In addition, the connecting surface, which is the front surface of the outer shell of the exhaust muffler, is not inclined with respect to the left-right direction of the vehicle so as to be perpendicular to the inclination angle of the exhaust pipe. Can be avoided at the expense of

In the above configuration,
The internal combustion engine is a multi-cylinder internal combustion engine in which a plurality of cylinders are arranged in the left-right direction of the vehicle, and the exhaust pipe has a junction where the exhaust pipes of the plurality of cylinders merge. The catalyst internal pipe may be connected in the same direction as the downstream end, and may be extended at an inclination angle with respect to the longitudinal direction of the vehicle in plan view of the vehicle.
According to the configuration, the merging portion of the exhaust pipe and the internal pipe of the catalyst are connected and extended at an inclination angle in the same direction as the downstream end of the merging portion. Therefore, the exhaust pipe and the internal pipe of the catalyst As a result, the exhaust gas can be uniformly flowed throughout the catalyst provided in the inner pipe of the catalyst, and the purification performance can be sufficiently exhibited.

In the above configuration,
The outer shell of the exhaust muffler is formed by welding the left and right divided bodies by welding, and the catalyst internal pipe matches the central axis of the connecting pipe with the joint portion of the left and right divided bodies in a plan view of the vehicle It is integrated with the exhaust muffler by being sandwiched between and welded to the left and right divided bodies, and the joint portion of the left and right divided bodies is formed along the longitudinal direction of the vehicle, and the catalyst The edge sandwiching the internal pipe may form a pipe joint that extends obliquely outward in the central axial direction of the internal catalyst pipe along the surface of the internal catalyst pipe.
According to the configuration, the outer shell of the exhaust muffler is constituted by the left and right divided bodies, and in the connecting surface, the central axis of the catalyst internal pipe is made to coincide with the joint portion of the left and right divided bodies in plan view of the vehicle. The exhaust muffler and the catalyst internal pipe are integrated by sandwiching the catalyst internal pipe in the divided body by sandwiching the catalyst internal pipe, and further, the connecting portion of the divided body is along the vehicle longitudinal direction, and the left and right Since the end edge of the divided body is formed in a pipe joint portion that extends obliquely outward in the central axial direction of the catalyst internal pipe along the surface of the catalyst internal pipe, welding with the left divided body to the catalyst internal pipe The bond line and the weld bond line with the right divided body are arranged in equal parts, and it is possible to balance the bond strength with the exhaust muffler on the left and right of the catalyst internal pipe.

In the above configuration,
The catalyst internal pipe has a circular cross section, and the connection port formed on the connection surface of the exhaust muffler and connected to the catalyst internal pipe is formed in an elliptical shape and welded to the outer peripheral surface of the catalyst internal pipe It may be combined.
According to the configuration, the connection port with the catalyst internal pipe of circular cross section provided on the connection surface of the exhaust muffler is formed in an elliptical shape, so welding of the connection port with the outer peripheral surface of the catalyst internal pipe The length can be increased to improve the coupling stiffness.

In the above configuration,
The exhaust muffler may have upper and lower partitions dividing the expansion chamber into upper and lower portions above the catalyst internal pipe in a side view of the vehicle.
According to the configuration, when a plurality of expansion chambers in the exhaust muffler are formed, the expansion chambers can be divided up and down so as not to interfere with the catalyst internal pipe, and a part of the catalyst internal pipe can be divided into one expansion chamber It is possible to configure other expansion chambers while being able to be accommodated and arranged in the

In the above configuration,
The upper and lower partition walls may be curved toward the upper side of the catalyst internal pipe at an end on the catalyst internal pipe side.
According to the configuration, since the end portion of the upper and lower partition walls on the catalyst inner pipe side is curved upward, the distance between the catalyst inner pipe and the upper and lower partition walls increases, and from the catalyst inner pipe to the upper and lower partitions The thermal influence of the above can be suppressed, and the thermal expansion deformation of the upper and lower partition walls can be suppressed.

In the above configuration,
An exhaust conduit may be connected to the downstream side of the catalyst internal pipe, and the exhaust conduit may extend along the upper and lower partition walls in a side view of the vehicle.
According to the configuration, since the exhaust conduit extends along the upper and lower partitions below the upper and lower partitions, it is possible to increase the length of the exhaust conduit while preventing interference between the exhaust conduit and the upper and lower partitions.

In the above configuration,
The exhaust muffler may have front and rear partitions dividing the expansion chamber back and forth, and the front and rear partitions may be inclined such that the lower part is separated from the upper part in the catalyst internal pipe.
According to the configuration, the exhaust muffler has the front and rear partitions dividing the expansion chamber back and forth, and the upper and lower partitions dividing the expansion chamber above and below the catalyst internal pipe in the vehicle side view. The lower part is closer to the catalyst internal pipe from the upper part, and the lower part is inclined to the side away from the catalyst internal pipe from the upper part, so the distance from the internal catalyst pipe to the front and rear partition can be secured more The exhaust resistance of the exhaust gas is reduced, and the exhaust efficiency of the exhaust gas can be increased.

According to the exhaust system of the straddle-type vehicle of the present invention,
When connecting the exhaust pipe to the connecting surface of the exhaust muffler, which has an inclination angle with respect to the longitudinal direction of the vehicle in a plan view of the vehicle and extends in the lateral direction of the vehicle in plan view of the vehicle, because of the arrangement restriction of the vehicle. The catalyst internal pipe continuously arranged in the extension direction of the downstream end of the exhaust pipe protrudes upstream from the connection surface and a part is disposed across the expansion chamber, and in the vehicle front-rear direction in plan view of the vehicle By being connected to the connection surface with an inclination angle, a sharp curve of the exhaust pipe near the upstream side of the catalyst internal pipe can be suppressed.
In addition, the connecting surface, which is the front surface of the outer shell of the exhaust muffler, is not inclined with respect to the left-right direction of the vehicle so as to be perpendicular to the inclination angle of the exhaust pipe. Can be avoided at the expense of

FIG. 1 is a right side view of a motorcycle according to an embodiment of the present invention. It is a perspective view which takes out and shows the exhaust system of Embodiment 1 provided with four primary exhaust pipes, a collection exhaust pipe, a catalyst internal pipe, and an exhaust muffler. It is a left side view of the exhaust system of Embodiment 1 which omitted illustration of a muffler protector and a part of primary exhaust pipe. It is a top view of the same exhaust system by IV-IV arrow in FIG. FIG. 5 is a bottom view of the exhaust system in which a muffler protector and a part of the primary exhaust pipe are not shown according to arrows VV in FIG. 3. FIG. 6 is a cross-sectional view of the collecting exhaust pipe, the catalyst internal pipe, and the discharge conduit taken along the line VI-VI in FIG. 5; It is a left view of the exhaust system of Embodiment 2 which omitted illustration of a muffler protector and a part of primary exhaust pipe. FIG. 8 is a plan view of the same exhaust system as viewed along arrows VIII-VIII in FIG. 7; FIG. 8 is a bottom view of the exhaust system where the muffler protector and the primary exhaust pipe are not shown by arrows IX-IX in FIG. 7 FIG. 8 is a rear cross-sectional view of the rear portion of the exhaust muffler according to XX arrow in FIG. 7;

An exhaust system of a straddle-type vehicle according to a first embodiment of the present invention will be described based on FIGS. 1 to 6.
In the description of the specification and the claims, the directions such as front, rear, left, right, up, down, and the like conform to the direction of the straddle-type vehicle equipped with the exhaust system of the straddle-type vehicle according to the present embodiment. In the present embodiment, the straddle-type vehicle is a motorcycle.
Further, in the drawing, an arrow FR indicates the front of the vehicle, LH indicates the left of the vehicle, RH indicates the right of the vehicle, and UP indicates the upper side of the vehicle.
In the figure, small black arrows schematically show the flow of exhaust gas.
The same applies to the second embodiment described with reference to FIG. 1 and FIGS. 7 to 10.

FIG. 1 is a right side view of the motorcycle 1 of the embodiment.
As shown in FIG. 1, a vehicle body frame 2 of a motorcycle 1 has a head pipe 20 for steerably supporting a front fork 11 on which a front wheel 10 is supported, and a pair of left and right main tubes extending rearward and downward from the head pipe 20. A frame 21, a single engine hanger 22 extending backward from the head pipe 20 at a steeper angle than the main frame 21, a pair of left and right pivot frames 23 extending downward from the rear of the main frame 21, and a rear of the main frame 21 The seat frame 24 extends upward from the rear, and the main frame 21 and the pivot frame 23 are integrally formed.

A power unit 4 including an internal combustion engine 3 disposed below the main frame 21 is supported at the rear of the main frame 21 in the body frame 2, the lower part of the engine hanger 22 and the lower part of the pivot frame 23.
The internal combustion engine 3 is an in-line four-cylinder four-stroke cycle internal combustion engine in which four cylinders are arranged in the vehicle width direction, and a crankcase 30 rotatably supporting a crankshaft 31 having an axis directed in the vehicle width direction; A cylinder block 32 formed on the upper end of the front portion 70a of the crankcase 31 by tilting the cylinder axis forward, a cylinder head 33 fastened to the upper end of the cylinder block 32, and a head cover 34 fastened to the upper end of the cylinder head 33 The oil pan 35 is attached to the lower part of the crankcase 30.

Further, a front end portion of a swing arm 13 pivotally supporting a rear wheel 12 driven by power generated by the internal combustion engine 3 at a rear end portion is supported by a lower portion of the pivot frame 23 so as to be vertically pivotable.
A fuel tank 14 is mounted on the main frame 21 above the internal combustion engine 3, and a passenger seat 15 disposed behind the fuel tank 14 is supported by a seat rail 24.

The head pipe 20 is covered from the front by the front cover 16, and the lower front of the fuel tank 14 and the front 70a of the vehicle body frame 2 are covered from both sides by the pair of left and right front side covers 17. The rear portion of the vehicle body frame 2 is covered from both sides by a pair of left and right rear side covers 18 disposed below the passenger seat 15.

In the exhaust device 5 of the present embodiment, the four primary exhaust pipes (the main exhaust pipe that connects the upstream end 50a to the four exhaust ports 33a on the front side surface of the cylinder head 33 and that discharges exhaust gas) From the “exhaust pipe” in the invention 50A and one collective exhaust pipe commonly connected to the downstream end of the four primary exhaust pipes 50A (the “joining portion” in the “exhaust pipe” in the present invention) 50B The exhaust pipe 50, the catalyst internal pipe 60 continuously provided in the extension direction of the downstream end 50b of the collecting exhaust pipe 50B, and the exhaust muffler 70 to which the catalyst internal pipe 60 is connected are provided.

In the motorcycle 1 of the present embodiment, since the internal combustion engine 3 is disposed horizontally with the crankshaft 31 oriented in the vehicle width direction, also with reference to FIG. 2, the four primary exhaust pipes 50A are It is connected to the four exhaust ports 33a opened on the front side surface of the cylinder head 33 corresponding to the cylinders individually, and bent from the front to the lower side and extended so as to wrap around the right lower side of the crankcase 30. And extends rearward along the right side surface of the oil pan 35 and is connected to the collecting exhaust pipe 50B.

An internal exhaust pipe 70 is connected to the downstream end 50b of the collecting exhaust pipe 50B in the extending direction, and an exhaust muffler 70 connected to the internal exhaust pipe 60 is located behind the oil pan 35 in the lower part of the internal combustion engine 3 And it is arrange | positioned ahead of the rear wheel 12, and forms what is called a belly lower muffler.
Most of the exhaust muffler 70 is covered with the muffler protector 71 from the right side, and the tail pipe 72 of the exhaust muffler 70 is disposed at the opening 71 a provided in the muffler protector 71.
FIG. 2 is a perspective view showing an exhaust device 5 including four primary exhaust pipes 50A, a collective exhaust pipe 50B, a catalyst internal pipe 60, and an exhaust muffler 70. The muffler protector 71 is shown removed from the exhaust muffler 70.

In the exhaust muffler 70, the outer shell 73 is composed of a plurality of types of constituent surfaces 74, and the internal surface 60 connected to the integrated exhaust pipe 50B is connected and the constituent surface 74 facing the front of the vehicle serves as the connecting surface 74A. The catalyst internal pipe 60 is connected to the connection surface 73A at an inclination angle θ with respect to the vehicle longitudinal direction xx in plan view of the vehicle (FIG. 4). reference).
In FIG. 2, reference numeral 75 denotes a mounting bracket for mounting the exhaust muffler 70 on the vehicle body frame 2, and reference numeral 76 denotes a mounting stay for mounting the muffler protector 71 on the exhaust muffler 70.

FIG. 3 is a left side view of the exhaust device 5 in which the muffler protector 71 and a part of the primary exhaust pipe 50A are not shown, and FIG. 4 is a plan view of the same exhaust device 5 taken along line IV-IV in FIG. It is.
As shown in FIG. 3, an expansion chamber 90 is provided in the internal space of the exhaust muffler 70, and as shown in FIG. 4, the catalyst internal pipe 60 is connected to the connecting surface 74A at the connecting surface 74A. It projects more upstream and is partially disposed in the expansion chamber 90.

Therefore, as shown in FIG. 4, the exhaust pipe 50 in the plan view of the vehicle, in the present embodiment, the downstream end 50b of the collective exhaust pipe 50B has an inclination angle θ with respect to the vehicle longitudinal direction xx. When the collecting exhaust pipe 50B is connected to the connecting surface 74A of the exhaust muffler 70 arranged to extend in the vehicle left-right direction yy, it is continued in the extending direction of the downstream end 50b of the collecting exhaust pipe 50B. A catalyst internal pipe 60 provided on the upstream side protrudes from the connection surface 74A and is partially disposed across the expansion chamber 90, and has an inclination angle θ with respect to the vehicle longitudinal direction xx in a plan view of the vehicle By being connected to the connecting surface 74A, a sharp curve of the collective exhaust pipe 50B in the vicinity of the upstream of the catalyst internal pipe 60 can be suppressed.
Further, the connection surface 74A, which is the front surface of the outer shell 73 of the exhaust muffler 70, is not inclined with respect to the vehicle lateral direction yy so as to be perpendicular to the inclination angle θ of the collecting exhaust pipe 50B. It is avoided to sacrifice the capacity of the expansion chamber 90 of the exhaust muffler 70.

Further, the internal combustion engine 3 of this embodiment is a four-cylinder internal combustion engine in which four cylinders are arranged in the vehicle left-right direction yy. As shown in FIG. 4, the exhaust pipe 50 is a primary exhaust pipe of each cylinder 50A and the collecting exhaust pipe 50B where they merge, the catalyst internal pipe 60 is connected to the downstream end 50b of the collecting exhaust pipe 50B in the same direction as the downstream end 50b, and the vehicle longitudinal direction x- It is extended at an inclination angle θ with respect to x.
Therefore, no bending occurs at the connection between the collective exhaust pipe 50B and the catalyst internal pipe 60, and as a result, the exhaust gas can be flowed evenly over the entire catalyst 65 provided in the catalyst internal pipe 60. And the purification performance can be fully exhibited.

As shown in FIG. 4, the outer shell 73 of the exhaust muffler 70 is configured by welding and connecting left and right divided

bodies

73L and 73R.
The catalyst internal pipe 60 is sandwiched between the left and right divided

bodies

73L and 73R in such a manner that the central axis P thereof coincides with the connecting portion 80 of the left and right divided

bodies

73L and 73R in the vehicle plan view It is integrated with the exhaust muffler by being welded and welded together.
In addition, although the joint portion 80 of the left and right divided

bodies

73L and 73R is formed along the vehicle longitudinal direction xx, the edge 81 sandwiching the catalyst internal pipe 60 is the catalyst internal pipe 60. A pipe joint 81 is formed to extend obliquely outward in the direction of the central axis P of the catalyst internal pipe 60 along the surface of the above.
Therefore, the weld joint line between the catalyst internal pipe 60 and the left divided body 73L and the weld joint line between the right divided body 73R are arranged equally, and the exhaust muffler 70 on the left and right of the catalyst internal pipe 60 The balance of the bond strength with.
Reference numeral 77 in FIGS. 4 and 3 denotes a heat shield plate.

As the cross-sectional shape 60a of the catalyst internal pipe 60 is shown in FIG. 4 by a two-dot chain line, the catalyst internal pipe 60 is a circular cross section. On the other hand, a connection port 82 which is formed on a connecting surface 74A extending in the vehicle left-right direction yy in the exhaust muffler 70 and connected to the catalyst internal pipe 60 having an inclination angle θ with respect to the vehicle longitudinal direction xx 4 is formed in an elliptical shape because the circular cross-section is obliquely inserted as shown by the opening shape 82a in FIG. 4 by a two-dot chain line, and the connection port 82 is provided inside the catalyst at the pipe joint portion 81. Welded to the outer peripheral surface of the tube 60 At that time, since the connection port 82 for inserting the catalyst internal pipe 60 is formed in an elliptical shape, the weld length between the connection port 82 and the outer peripheral surface of the catalyst internal pipe 60 is increased, and the coupling rigidity is improved. ing.

As shown in FIG. 3, the front part 70 a of the exhaust muffler 70 is formed to have a small vertical height and the rear part 70 b has a large vertical height. In the first embodiment, the rear part 70 b has a large vertical height. The inside of the expansion chamber 90 is divided up and down by the upper and lower partitions 91, and a lower expansion chamber 90A and an upper expansion chamber 90B are formed.
A welding flange 91a formed by bending around the upper and lower partition 91 is fixed to the inner surface of the outer shell 93 of the exhaust muffler 70 above the catalyst internal pipe 60 in a side view of the vehicle.

That is, since the exhaust muffler 70 has upper and lower partitions 91 dividing the expansion chamber 90 up and down above the catalyst internal pipe 60 in a side view of the vehicle, a plurality of expansion chambers 90 in the exhaust muffler 70 are provided. The expansion chamber 90 can be divided up and down so as not to interfere with the catalyst internal pipe 60, and a part of the catalyst internal pipe 60 can be accommodated and arranged in one expansion chamber 90, and another expansion chamber is configured. It becomes possible.
Specifically, the upper expansion chamber 90B can be configured above the lower expansion chamber 90A while arranging a part of the catalyst internal pipe 60 in the lower expansion chamber 90A.

Further, a discharge conduit 61 is connected to the downstream side of the catalyst internal pipe 60 partially disposed in the lower expansion chamber 90A, and the discharge conduit 61 is extended along the upper and lower partitions 91 in a side view of the vehicle . As such, since the exhaust conduit 61 is extended along the upper and lower partitions 91 below the upper and lower partitions 91, the length of the exhaust conduit 61 can be increased while preventing interference between the exhaust conduit 61 and the upper and lower partitions 91. it can.

The upper and lower partition walls 91 are curved toward the upper side of the catalyst internal pipe 60 at the end 91b on the side of the catalyst internal pipe 60. Therefore, the distance between the catalyst internal pipe 60 and the upper and lower partition walls 91 is In addition, the thermal influence from the catalyst internal pipe 60 to the upper and lower partition walls 91 is suppressed, and the thermal expansion deformation of the upper and lower partition walls 91 is suppressed.

Further, as shown in FIG. 3, referring also to FIG. 4, communication pipe 92 is provided to penetrate upper and lower partition walls 91, and inlet opening 92a of communication pipe 92 opens toward lower expansion chamber 90A.
The outlet opening 61b of the discharge conduit 61 in the lower expansion chamber 90A and the inlet opening 92a of the communication pipe 92 are spaced apart to increase the gas flow distance to increase the muffling effect.
The downstream side of the communication pipe 92 is curved backward in the upper expansion chamber 90B, and the downstream end 92b is supported by a support stay 93 erected on the upper and lower partition walls 91, and the front end of the downstream end 92b The communication pipe 92 is provided with a porous portion 92 c.

In the upper expansion chamber 90B, the upstream side of the tail pipe 72 is provided through the outer shell 93 of the exhaust muffler 70, and the inlet opening 93a is opened. Further, the downstream end 72b of the tail pipe 72 is opened to the outside air to release the exhaust gas.
That is, the exhaust gas passes from the exhaust pipe 50 (50A, 50B) through the catalyst internal pipe 60, is purified by the catalyst 65 in the catalyst internal pipe 60, and enters the lower expansion chamber 90A from the outlet opening 61b of the exhaust conduit 61 From the inside of the lower expansion chamber 90A through the communicating pipe 92, the porous portion 92c passes through the inside of the lower expansion chamber 90C, enters the upper expansion chamber 90B, is muffled, and is released through the tail pipe 72 to the outside air.
The lower expansion chamber 90A can be referred to as a first expansion chamber, and the upper expansion chamber 90B can be referred to as a second expansion chamber.

FIG. 5 is a bottom view of the exhaust device 5 in which the muffler protector 71 and a part of the primary exhaust pipe 50A are not shown, as viewed in the direction of arrows VV in FIG. In FIG. 5, only the inside of the lower expansion chamber 90A is shown in the exhaust muffler 70, and the exhaust conduit 61 on the downstream side of the catalyst internal pipe 60 is curved to the right, and the outlet opening 61b of the exhaust conduit 61 is Is increased to the right side, and the gas flow distance between the inlet opening 92a of the communication pipe 92 opened to the lower expansion chamber 90A is increased to increase the muffling effect.
Reference numeral 78 shown in FIGS. 5 and 3 is a protective cover plate.

FIG. 6 is a cross-sectional view of the collecting exhaust pipe 50B, the catalyst internal pipe 60, and the discharge conduit 61 taken along line IV-IV in FIG. A catalyst 65 is loaded inside the catalyst internal pipe 60, and the catalyst 65 is an exhaust gas purification catalyst, for example, a three-way catalyst supported on a honeycomb metal carrier.
Although the catalyst internal pipe 60 of this embodiment has a multi-pipe structure as shown in FIG. 6, the catalyst shown by broken lines in FIG. 3 to FIG. 5 and FIG. 7 to FIG. In the internal pipe 60, the outermost shell pipe 60b in FIG. 6 is not shown.

A exhaust system for a straddle-type vehicle according to a second embodiment of the present invention will be described based on FIGS. 1 and 7 to 10.
In the second embodiment, the structure of the two-wheeled vehicle 1 as a straddle-type vehicle, the structural relationship and exhaustion relationship between the exhaust pipe 50 (the primary exhaust pipe 50A and the collecting exhaust pipe 50B), the catalyst internal pipe 60 and the exhaust muffler 70. The second embodiment is the same as the first embodiment described above, except for the structure in the exhaust muffler.
The structure of the catalyst internal pipe 60 is also the same as that of the first embodiment.
Therefore, parts similar to those of Embodiment 1 are assigned the same reference numerals, and explanations of similar functions and effects with similar constructions will be omitted and simplified, and differences will be mainly described below.

FIG. 7 is a left side view of the exhaust device 5 of the second embodiment in which the muffler protector 71 and a part of the primary exhaust pipe 50A are not shown, and FIG. 8 is a similar exhaust according to arrows VIII-VIII in FIG. FIG. 5 is a plan view of the device 5;
As shown in FIG. 7, an expansion chamber 90 is provided in the internal space of the exhaust muffler 70, and as shown in FIG. 8, the catalyst internal pipe 60 has a connecting surface with an inclination angle θ similar to that of the first embodiment. At a position connected to 74 A, it protrudes upstream from the connecting surface 74 A and a part thereof is disposed in the expansion chamber 90.

Further, the front part 70a of the exhaust muffler 70 has a small vertical height, and the rear part 70b has a large vertical height. In the second embodiment, the expansion chamber is located in front of the rear part 70b having a large vertical height. It has front and back partitions 95 which divide 90 into the front and back.
The front and rear partitions 95 are fixed by welding a welding flange portion 95a bent around the periphery thereof to the inner surface of the outer shell 73 of the exhaust muffler 70.

In the exhaust muffler 70, the inside of the expansion chamber 90 is divided back and forth by the front and rear partitions 95 extending in the vertical direction, and a front expansion chamber 90C is formed in front of the front and rear partitions 95.
The rear of the front and rear partition 95 is further divided up and down by the upper and lower partitions 96 to form a rear upper expansion chamber 90D and a rear lower expansion chamber 90E.
A welding flange 96a formed by bending the upper and lower partitions 96 above the catalyst internal pipe 60 in a side view of the vehicle is welded and fixed to the inner surface of the outer shell 73 of the exhaust muffler 70.
In the second embodiment, the catalyst internal pipe 60 is connected to the front expansion chamber 90C in the same arrangement as the first embodiment, but the discharge conduit 61 as in the first embodiment is not provided.

As described above, since the exhaust muffler 70 has the upper and lower partitions 96 dividing the expansion chamber 90 up and down above the catalyst internal pipe 60 in a side view of the vehicle, a plurality of expansion chambers 90 in the exhaust muffler 70 are configured. In this case, the expansion chamber 90 can be divided up and down so as not to interfere with the catalyst internal pipe 60, and a part of the catalyst internal pipe 60 can be accommodated and arranged in one expansion chamber 90, while the other expansion chambers can be It is possible to configure.

As shown in FIG. 7, in the second embodiment, the exhaust muffler 70 has front and rear partitions 95 that divide the expansion chamber 90 back and forth, and the front and rear partitions 95 have a lower part 95 b from the upper part 95 c through the catalyst internal pipe 60 It is inclined to leave.
Since the exhaust muffler also has upper and lower partitions 96 dividing the expansion chamber 90 up and down above the catalyst internal pipe 60 in a side view of the vehicle, the lower part 95b of the front and rear partition 95 is closer to the catalyst internal pipe 60 than the upper part 95c. On the other hand, since the lower part 95b is inclined more to the side away from the catalyst internal pipe 60 than the upper part 95c, the distance from the catalyst internal pipe 60 to the front and rear partition 95 can be further secured. Flow resistance is reduced, and the exhaust gas emission efficiency is enhanced.

In the exhaust muffler 70 according to the second embodiment, as shown in FIG. 7, referring also to FIG. 8, the catalyst internal pipe 60 is connected to the connection surface 74A of the front exhaust muffler 70 to be in the front expansion chamber 90C. The first communication pipe 97 which is open and penetrates the front and rear partition 95 from the front expansion chamber 90C to the rear upper expansion chamber 90D, and the upper and lower partitions 96 from the rear upper expansion chamber 90D to the rear lower expansion chamber 90E A second communication pipe 98 penetrating is provided.
In the lower rear expansion chamber 90E, the upstream side of the tail pipe 72 is provided to pass through the outer shell 73 and the upper and lower partitions 96 of the exhaust muffler 70 and pass through the upper rear expansion chamber 90D, and the inlet opening 72a is opened. Do. Further, the downstream end 72b of the tail pipe 72 is opened to the outside air to release the exhaust gas.

That is, the exhaust gas passes from the exhaust pipe 50 (50A, 50B) through the catalyst internal pipe 60, is purified by the catalyst 65 in the catalyst internal pipe 60, enters the front expansion chamber 90C, and is in the front expansion chamber 90C. Then, it passes through the first communication pipe 97, enters the rear upper expansion chamber 90D, passes through the second communication pipe 98, enters the rear upper expansion chamber 90D, is muted, and is released through the tail pipe 72 to the outside air.
The front expansion chamber 90C may be referred to as a first expansion chamber, the rear upper expansion chamber 90D may be referred to as a second expansion chamber, and the rear lower expansion chamber 90E may be referred to as a third expansion chamber.

FIG. 9 is a bottom view of the exhaust device 5 with the muffler protector 71 and the primary exhaust pipe 50A omitted in FIG. 7 as viewed in the direction of arrows IX-IX. In FIG. 9, only the inside of the front expansion chamber 90C and the rear lower expansion chamber 90E are shown in the exhaust muffler 70, and the downstream side of the catalyst internal pipe 60 is not provided with the discharge conduit 61 of the first embodiment. It is shown opening into the expansion chamber 90C.
In FIG. 9 and FIG. 7, reference numeral 79 denotes a soundproof material storage unit.

FIG. 10 is a rear cross-sectional view of the rear portion 70B of the exhaust muffler 70 as viewed in the direction of arrows XX in FIG. The rear portion 70b is divided into a rear upper expansion chamber 90D and a rear lower expansion chamber 90E by upper and lower partitions 96 dividing the expansion chamber 90 up and down, and the outlet opening 97b of the first communicating pipe 97 in the rear upper expansion chamber 90D; The inlet port 98a of the second communication pipe 98 is spaced apart from the inlet port 98a to increase the gas flow distance to increase the muffling effect.
Although the outlet opening 98b of the second communication pipe 98 extends to the right in the lower rear expansion chamber 90E, as shown in FIG. 8, the outlet of the second communication pipe 98 in the lower rear expansion chamber 90E The gas flow distance is also increased between the opening 98 b and the inlet opening 72 a of the tail pipe 72.

As mentioned above, although Embodiment 1 and Embodiment 2 of this invention were demonstrated, the aspect of this invention is not limited to the said embodiment, What contains in various aspects within the range of the summary of this invention is included Of course. For example, the internal combustion engine is not limited to an in-line four-cylinder engine, and the straddle-type vehicle is not limited to a motorcycle, and includes a buggy vehicle and the like.
Although the internal combustion engine has been specifically described in the embodiment in the left and right arrangement shown in the embodiment for the sake of convenience of the description, the present invention is also included in the present invention even if the left and right arrangement is different.

DESCRIPTION OF SYMBOLS 1 ... Motorcycle, 3 ... Internal combustion engine, 4 ... Power unit, 5 ... Exhaust system, 30 ... Crankcase, 33 ... Cylinder head, 33a ... Exhaust port, 35 ... Oil pan, 50 ... Exhaust pipe, 50a ... Upstream end, 50b ... downstream end, 50A ... primary exhaust pipe ("exhaust pipe" in the present invention), 50B ... collective exhaust pipe ("joining portion" in "exhaust pipe" in the present invention) 60 ... catalyst internal pipe, 60a ... cross section Shape, 61: discharge conduit, 61b: outlet opening, 65: catalyst, 70: exhaust muffler, 70a: front, 70b: rear, 72: tail pipe, 72a: inlet opening, 72b: downstream end, 73: outer shell, 73L: left divided body, 73R: left divided body, 74: construction surface, 74A: connection surface, 80: coupling portion, 81: end edge, pipe joint portion, 82: connection port, 82a: opening shape, 90: Expansion chamber 90A lower expansion chamber 90B upper expansion chamber 90C front expansion chamber 90D rear upper expansion chamber 90E rear lower expansion chamber 91 upper and lower partition walls 91b ... end part, 92 ... communication pipe, 95 ... front and back partition, 95a ... lower part, 95b ... top, 96 ... upper and lower partition, 97 ... first communication pipe, 98 ... second communication pipe, xx ... vehicle longitudinal direction, y-y ... vehicle left-right direction, P ... central axis of the catalyst internal pipe 60, θ ... inclination angle

Claims

A power unit (4) including an internal combustion engine (3) is mounted on a straddle-type vehicle (1),
An exhaust pipe (50) is connected to the internal combustion engine (3) to form an exhaust gas passage which is connected at the upstream end thereof to discharge the exhaust gas, and is connected to the downstream end (50b) of the exhaust pipe (50) in the extending direction And an exhaust muffler (70) to which the catalyst internal pipe (60) is connected,
In an exhaust system of a straddle-type vehicle having an expansion chamber (90) in the internal space of the exhaust muffler (70),
In the exhaust muffler (70), the outer shell (73) is composed of a plurality of types of component surfaces (74), the component internal pipe (60) is connected, and the component surface (74) facing the front of the vehicle is a connection surface The catalyst internal pipe (60) which is disposed to extend in the vehicle left-right direction (yy) as (74A) and continuously provided to the exhaust pipe (50) connected to the connection surface (74A) with an inclination angle (θ) with respect to -x),
At a position where the catalyst internal pipe (60) is connected to the connection surface (74A), a part of the catalyst internal pipe (60) is disposed across the inside of the expansion chamber (90). Exhaust system for straddle-type vehicles.
The internal combustion engine (3) is a multi-cylinder internal combustion engine in which a plurality of cylinders are arranged in the left-right direction (y-y) of the vehicle.
The exhaust pipe (50) has a junction (50B) where the exhaust pipes (50A) of the plurality of cylinders merge, and the downstream end (50b) of the junction (50B) is the same as the downstream end (50b) The catalyst internal pipe (60) is connected in a direction and extended at an inclination angle (θ) with respect to a vehicle longitudinal direction (x-x) in plan view of the vehicle. Exhaust system of a straddle-type vehicle according to claim
The outer shell (73) of the exhaust muffler (70) is constructed by welding the left and right divided bodies (73L, 73R) together,
In the catalyst connection pipe (60), the central axis (P) of the connection surface (74A) is made to coincide with the coupling portion (80) of the left and right divided members (73L, 73R) in a plan view of the vehicle. It is integrated with the exhaust muffler (70) by being sandwiched between and welded to the left and right divided members (73L, 73R),
The connecting portion (80) of the left and right divided bodies (73L, 73R) is formed along the longitudinal direction (x-x) of the vehicle and is an edge (81) sandwiching the internal catalyst pipe (60) The present invention is characterized in that a pipe joint (81) is formed to extend obliquely outward in the central axis (P) direction of the catalyst internal pipe (60) along the surface of the catalyst internal pipe (60). The exhaust system for a straddle-type vehicle according to claim 1 or 2.
The catalyst internal pipe (60) has a circular cross section, and a connection port (82) formed on the connection surface (74A) of the exhaust muffler (70) and connected to the catalyst internal pipe (60) is The exhaust system for a saddle-ride type vehicle according to any one of claims 1 to 3, wherein the exhaust system is formed in an elliptical shape and welded to an outer peripheral surface of the catalyst internal pipe (60).
The exhaust muffler (70) has upper and lower partition walls (91, 96) dividing the expansion chamber (90) up and down above the catalyst internal pipe (60) in a vehicle side view. An exhaust system for a straddle-type vehicle according to any one of claims 1 to 4.
6. The crucible according to claim 5, wherein the upper and lower partition walls (91) are curved toward the upper side of the catalyst internal pipe (60) at an end portion on the catalyst internal pipe (60) side. Exhaust system for riding vehicles.
An exhaust conduit (61) is connected to the downstream side of the catalyst internal pipe (60), and the exhaust conduit (61) extends along the upper and lower partitions (91) in a side view of the vehicle. The exhaust system for a straddle-type vehicle according to claim 5 or 6, characterized in that
The exhaust muffler (70) has front and rear partitions (95) for dividing the expansion chamber (90) back and forth, and the front and rear partitions (95) have the lower part (95b) closer to the upper part (95c). 6. Exhaust system according to claim 5, characterized in that it is inclined away from the tube (60).