WO2023053996A1

WO2023053996A1 - Saddle-type vehicle

Info

Publication number: WO2023053996A1
Application number: PCT/JP2022/034613
Authority: WO
Inventors: 潤一中野; 祐樹鵜澤
Original assignee: 本田技研工業株式会社
Priority date: 2021-09-29
Filing date: 2022-09-15
Publication date: 2023-04-06

Abstract

In the present invention, an influence on engine output characteristics is reduced and a minimum ground clearance is easily ensured while facilitating early warming of a catalyst.　In the present invention, a catalyst 61 is covered with an outer cylinder 62 larger in diameter than an exhaust pipe (51). The outer cylinder 62 and the exhaust pipe (51) are connected by a diameter expansion part 63 expanded in diameter toward the outer cylinder 62. A rear wall 12W of an engine (12) extends rear upward or upward from the rear end of a bottom 12S of the engine (12). The diameter expansion part 63 is located rear downward from the rear wall 12W of the engine (12). An inclined surface 63M of the diameter expansion part 63 is along the rear wall 12W of the engine (12) in a side view of a vehicle body.

Description

saddle-riding vehicle

The present invention relates to a saddle-ride type vehicle.

A straddle-type vehicle is known which includes an engine supported by a vehicle body frame and an exhaust system having an exhaust pipe connected to the engine (for example, Patent Document 1). In this type of saddle-ride type vehicle, a configuration is disclosed in which a catalyst for purifying exhaust gas is arranged in front of or directly under the upright engine to achieve early warm-up of the catalyst (for example, Patent Document 2).

Japanese Patent Application Laid-Open No. 2020-015450 JP 2016-056790 A

However, if the catalyst is placed in front of the upright engine, the catalyst and the exhaust port will be close to each other, which may affect the output characteristics of the engine. In addition, when the catalyst is arranged directly under the engine, the ground clearance of the vehicle may become too low.
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to facilitate early warm-up of the catalyst, reduce the influence on the engine output characteristics, and facilitate securing the minimum ground clearance.

This specification includes all the contents of Japanese Patent Application/Japanese Patent Application No. 2021-159396 filed on September 29, 2021.
In order to achieve the above object, a straddle-type vehicle comprising an engine supported by a vehicle body frame and an exhaust system connected to the engine and having an exhaust pipe and a catalyst is provided, wherein the catalyst is larger than the exhaust pipe. The outer cylinder and the exhaust pipe are connected by an enlarged diameter portion that expands toward the outer cylinder, and the rear wall of the engine extends upward from the rear end of the bottom of the engine. Alternatively, it extends rearward and upward, the enlarged diameter portion is positioned rearward and downward of the rear wall of the engine, and the inclined surface of the enlarged diameter portion extends along the rear wall of the engine when viewed from the side of the vehicle body. It is characterized by

While making it easier to warm up the catalyst early, it reduces the impact on the engine output characteristics and makes it easier to secure the minimum ground clearance.

FIG. 1 is a side view of a straddle-type vehicle according to an embodiment of the invention. FIG. 2 is a side view showing the power unit together with its peripheral configuration. FIG. 3 is a bottom view of the power unit together with its peripheral configuration. FIG. 4 is a diagram showing a side cross-section of the catalytic converter and the sub-chamber together with the peripheral configuration.

Embodiments of the present invention will be described below with reference to the drawings. In the description, directions such as front, rear, left, right, and up and down are the same as the directions with respect to the vehicle body unless otherwise specified. In each figure, FR indicates the front of the vehicle body, UP indicates the upper side of the vehicle body, and LH indicates the left side of the vehicle body.

[Embodiment]
FIG. 1 is a side view of a straddle-type vehicle 10 according to an embodiment of the invention.
A straddle-type vehicle 10 includes a body frame 11, a power unit 12 supported by the body frame 11, a front fork 14 supporting a front wheel 13 in a steerable manner, a swing arm 16 supporting a rear wheel 15, and a passenger seat. The vehicle includes a seat 17 .
The saddle-ride type vehicle 10 is a vehicle in which an occupant sits astride a seat 17 . The seat 17 is provided above the rear portion of the body frame 11 .

The body frame 11 includes a head pipe 18 provided at the front end of the body frame 11 , a front frame 19 positioned behind the head pipe 18 , and a rear frame 20 positioned behind the front frame 19 . A front end portion of the front frame 19 is connected to the head pipe 18 .
Seat 17 is supported by rear frame 20 .

The front fork 14 is supported by a head pipe 18 so as to be steerable left and right. The front wheel 13 is supported by an axle 13 a provided at the lower end of the front fork 14 . A steering handle 21 gripped by a passenger is attached to the upper end of the front fork 14 .

The swing arm 16 is supported by a pivot shaft 22 supported by the vehicle body frame 11 . The pivot shaft 22 is a shaft extending horizontally in the vehicle width direction. A pivot shaft 22 is inserted through the front end of the swing arm 16 . The swing arm 16 swings up and down around the pivot shaft 22 .
The rear wheel 15 is supported by an axle 15 a provided at the rear end of the swing arm 16 .

Power unit 12 is arranged between front wheel 13 and rear wheel 15 and supported by body frame 11 .
Power unit 12 is an internal combustion engine. The power unit 12 includes a crankcase 23 and a cylinder portion 24 that houses reciprocating pistons. An exhaust device 25 is connected to an exhaust port of the cylinder portion 24 .
The output of power unit 12 is transmitted to rear wheels 15 by a driving force transmission member that connects power unit 12 and rear wheels 15 .

The straddle-type vehicle 10 also includes a front fender 26 that covers the front wheels 13 from above, a rear fender 27 that covers the rear wheels 15 from above, a step 28 on which the passenger puts his or her feet, and a fuel for storing the fuel used by the power unit 12. and a tank 29 .
A front fender 26 is attached to the front fork 14 . The rear fender 27 and step 28 are provided below the seat 17 . The fuel tank 29 is supported by the vehicle body frame 11 .

The saddle-ride type vehicle 10 includes a vehicle body cover 30 that covers each part of the vehicle body. The vehicle body cover 30 protects a front cowl 31 covering the front part of the vehicle body from the front, a side cowl 32 covering the front part of the vehicle body from the left and right, a rear cowl 33 covering the rear part of the vehicle body from the left and right, and the front part and lower part of the crankcase 23. and an undercover 34 . In addition, in FIG. 1, the undercover 34 is indicated by a two-dot chain line.

This straddle-type vehicle 10 employs a mono-cushion structure in which a single rear cushion 37 mitigates or absorbs the impact transmitted from the rear wheel 15 to the body frame 11 via the swing arm 16 . The rear cushion 37 is interposed between the swing arm 16 and the rear portion of the front frame 19 . An upper portion of the rear cushion 37 is connected to a cross member 16C (see FIG. 4 described later) that bridges the left and right swing arms 16. As shown in FIG. The configuration of the rear cushion 37 and the support structure thereof need not be limited to the above configurations.

FIG. 2 is a side view showing the power unit 12 together with its peripheral configuration.
The power unit 12 is located forward of the seat 17 and below the front frame 19 and between the front wheels 13 and the rear wheels 15 . The power unit 12 is a single-cylinder engine (internal combustion engine) called a forward tilting type or an upright type in which a cylinder portion 24 rises forward and upward from a front portion of a crankcase 23 . An oil pan 23</b>P is provided below the crankcase 23 .

The oil pan 23P is a portion that stores engine oil that lubricates each part of the power unit 12 corresponding to the engine, and is located at the bottom of the power unit 12. The bottom portion of the oil pan 23P constitutes the bottom portion 12S of the power unit 12, and the rear wall of the crankcase 23 including the rear wall of the oil pan 23P constitutes the rear wall 12W of the power unit 12.

In this configuration, the bottom portion 12S is a surface that extends substantially horizontally in the front-rear direction, and the rear wall 12W is a surface that extends rearward and upward. As viewed from the side of the vehicle body, the angle θ1 between the rear wall 12W and the bottom portion 12S is larger than 90° and smaller than 180° (that is, an obtuse angle). The angles of the bottom portion 12S and the like change depending on whether or not the occupant is seated on the seat 17, and each drawing shows a state in which the occupant is not seated.
However, depending on the power unit 12, the angles of the bottom portion 12S and the rear wall 12W and the angle θ1 may be changed as appropriate. For example, the rear wall 12W may extend upward (corresponding to the vertical direction), and the angle θ1 may be 90°. Reference numeral 28R in FIG. 2 denotes a brake pedal operated by the foot placed on the step 28. As shown in FIG.

The exhaust device 25 includes an upstream exhaust pipe 51 connected to the front surface of the cylinder portion 24, a catalytic converter 52 connected to the rear end corresponding to the downstream end of the exhaust pipe 51, a sub-chamber 53 connected downstream of the catalytic converter 52, a sub- A downstream side exhaust pipe 54 connected to the downstream side of the chamber 53 and a muffler 55 connected to the downstream side of the downstream side exhaust pipe 54 are provided. The sub-chamber 53 corresponds to the "expansion chamber" of the present invention, and the muffler 55 corresponds to the "silencing chamber" of the present invention. In FIG. 2, a muffler cover 56 that covers the muffler 55 is indicated by a chain double-dashed line.

The upstream exhaust pipe 51 is an exhaust pipe directly connected to the exhaust port in the cylinder portion 24 . The upstream exhaust pipe 51 extends downward from the front surface of the cylinder portion 24 and then bends rearward to extend rearward just below the power unit 12 .
FIG. 3 is a bottom view of the power unit 12 together with its peripheral configuration. A reference symbol C1 in FIG. 3 denotes a line extending longitudinally from the vehicle width center, and is referred to as "vehicle width center line C1". As shown in FIG. 3, the upstream exhaust pipe 51 is arranged directly under the power unit 12 at a position overlapping the vehicle width center line C1, and extends linearly toward the rear of the vehicle body. A rear end portion of the upstream exhaust pipe 51 is positioned rearwardly and downwardly of the power unit 12 .

The catalytic converter 52 includes a catalyst 61 that purifies exhaust gas through oxidation/reduction reactions, and a cylindrical outer cylinder 62 that covers the catalyst 61 . An enlarged diameter portion 63 is provided between the upstream side exhaust pipe 51 and the outer cylinder 62 . The diameter-enlarging portion 63 is formed in a tubular shape whose diameter increases from the upstream exhaust pipe 51 toward the outer cylinder 62, and functions as a connecting part for connecting the upstream exhaust pipe 51 and the outer cylinder 62 having different outer diameters. do.
In this configuration, as shown in FIG. 2, the catalytic converter 52 is disposed rearwardly and downwardly of the power unit 12, and the inclined surface 63M forming the outer peripheral surface of the enlarged diameter portion 63 is located on the power unit 12 when viewed from the side of the vehicle body. Along the rear wall 12W, it is close to the rear wall 12W.

With this catalyst layout, the enlarged diameter portion 63 and the catalytic converter 52 can be arranged by effectively utilizing the space left behind the power unit 12 . Furthermore, since the enlarged diameter portion 63 and the catalytic converter 52 can be arranged above the enlarged diameter portion 63 and the catalytic converter 52 compared to the case where the enlarged diameter portion 63 and the catalytic converter 52 are arranged directly below the power unit 12, it becomes easy to sufficiently secure the minimum ground clearance.
Also, the axis of the catalytic converter 52 coincides with the axis of the upstream exhaust pipe 51 directly below the oil pan 23P. Therefore, the exhaust path from the upstream side exhaust pipe 51 to the catalytic converter 52 can be shortened, and they can be arranged compactly. The internal structure of this catalytic converter 52 will be described later.

The sub-chamber 53 functions as an expansion chamber that expands the exhaust gas. This sub-chamber 53 is provided downstream of the catalytic converter 52 and expands the exhaust gas that has passed through the catalytic converter 52 .
As shown in FIGS. 2 and 3 , the sub-chamber 53 is continuous with the rear end of the outer cylinder 62 and is formed in a box shape that protrudes upward from the outer cylinder 62 in the vehicle width direction. Also, the lower surface of the sub-chamber 53 is substantially aligned with the lowest position of the outer cylinder 62 .
The sub-chamber 53 is located in the space behind the power unit 12, in front of the rear wheel 15, and below the swing arm 16, so that it is not located below the outer cylinder 62 and can create a large-capacity expansion chamber. It is advantageous for reducing the exhaust pressure, concentrating the mass, and the like.

The downstream exhaust pipe 54 extends outward in the vehicle width direction from the sub-chamber 53 and is connected to a muffler 55 .
The muffler 55 is supported laterally of the rear wheel 15 and covered with a muffler cover 56 . The muffler 55 further reduces the exhaust pressure of the exhaust gas whose exhaust pressure has been reduced in the sub-chamber 53 and discharges it outside the vehicle. Since the sub-chamber 53 is provided, the volume of the muffler 55 can be reduced as compared with the case where the sub-chamber 53 is not provided, and the size of the muffler 55 can be reduced.
As shown in FIG. 2 , in this configuration, the muffler 55 is arranged below the seat 17 and on the front side of the rear wheel 15 . This is advantageous for mass concentration, and the downstream side exhaust pipe 54 can be shortened.

Here, in FIG. 2, the position of the lower end connecting portion of the rear cushion is indicated by P1, and the connecting portion between the muffler 55 and the downstream side exhaust pipe 54 is indicated by P2.
In this configuration, the connecting portion P2 between the muffler 55 and the downstream side exhaust pipe 54 is located behind the position P1 of the lower end connecting portion of the rear cushion 37. As shown in FIG. Therefore, even if the muffler 55 is arranged below and closer to the front than the seat 17, the muffler 55 does not become an obstacle when the occupant who straddles the seat 17 touches the ground. Therefore, it becomes easy to sufficiently secure the occupant's foot grounding ability while concentrating the mass and making the exhaust system compact.
Note that the layout of the downstream side exhaust pipe 54 and the position of the muffler 55 may be changed as appropriate within a range in which the occupant's feet can be satisfactorily secured.

FIG. 4 is a side cross-sectional view of the catalytic converter 52 and the sub-chamber 53 together with the peripheral configuration.
The catalytic converter 52 includes a plurality of (two in this configuration)

catalysts

61A and 61B as the catalyst 61 . Each

catalyst

61A, 61B is supported in a cylindrical cylinder 65, and the

catalysts

61A, 61B are arranged on the same axis by joining the cylinders 65A to each other.
The

catalysts

61A and 61B are, for example, porous honeycomb structures coated with platinum, palladium, rhodium, etc., and are also called honeycomb three-way catalysts. In this configuration, the

catalysts

61A and 61B are arranged on the same axis as the upstream side exhaust pipe 51 .

As shown in FIG. 4, a cylindrical body 65 supporting catalyst 61A is positioned inside outer cylinder 62 of catalytic converter 52, and cylindrical body 65 supporting catalyst 61B forms partition wall 53A that partitions the space within sub-chamber 53. supported by That is, the partition 53A also functions as a holder for the catalyst 61. As shown in FIG. The partition 53A may be configured to completely partition the space in the sub-chamber 53, or may be configured to not completely partition the space in the sub-chamber 53 by partially opening the partition 53A. . The rear part of the catalyst 61A and the entire catalyst 61B are located in the sub-chamber 53 by being located behind the outer cylinder 62 .
Thus, in this configuration, only the front catalyst 61 A is positioned within the outer cylinder 62 , and the rear part of the catalyst 61 A and the entire catalyst 61 B are positioned within the sub-chamber 53 .

As shown in FIG. 3, the

catalysts

61A and 61B are arranged with their vehicle width centers on the vehicle width center line C1 along the longitudinal direction of the vehicle when viewed from the top of the vehicle body, and when viewed from the side of the vehicle (see FIG. 4), the

catalysts

61A and 61B are arranged upstream. It is arranged on the same axis as the side exhaust pipe 51 . As a result, the path from the upstream side exhaust pipe 51 to the

catalysts

61A and 61B can be straightened and appropriately shortened, and the exhaust gas from the upstream side exhaust pipe 51 can be directed smoothly toward the

catalysts

61A and 61B. can flow to
The exhaust gas that has passed through the

catalysts

61A and 61B is expanded in the sub-chamber 53 and then passed through the downstream side exhaust pipe 54 and output to the muffler 55 .
A gap is provided between the cylinder 65 and the outer cylinder 62, and the high-temperature exhaust gas flows into this gap, so that the catalyst 61A can be quickly heated from the surroundings and kept warm. In addition, since high-temperature exhaust gas also flows around the catalyst 61B, the catalyst 61B can be quickly heated and kept warm. As a result, the

catalysts

61A and 61B can be brought to the activation temperature quickly, and the exhaust gas can be efficiently purified.

In FIG. 4, the length from the front end of catalyst 61A to the rear end of catalyst 61B is indicated by value LA. The length required for arranging these

catalysts

61A and 61B includes the length of the cylindrical body 65, so it is the value LB (length LB>length LA). The length LB is greater than the length LC of the sub-chamber 53 in side view of the vehicle body (length LB>LC).
In this configuration, the length LC required for arranging the

catalysts

61A and 61B in the side view of the vehicle body is longer than the sub-chamber 53, so the large-sized catalyst 61 can be arranged regardless of the size of the sub-chamber 53. is.

In addition, since the cylinder 65 supporting the catalyst 61 is supported by the outer cylinder 62 and the partition wall 53A of the sub-chamber 53 with a space therebetween in the front-rear direction, it is possible to sufficiently secure the support strength of the

catalysts

61A and 61B. Further, since the partition wall 53A of the sub-chamber 53 is used to support the cylindrical body 65, dedicated parts for supporting the cylindrical body 65 can be omitted or reduced, and the number of parts required for supporting the catalyst 61 can be reduced.

In this configuration, the case where the

catalysts

61A and 61B have the same size is exemplified, but they do not have to have the same size. In the present invention, the

catalysts

61A and 61B may differ in size, object to be purified, structure, shape, or the like. Also, the number of catalysts 61 is not limited to two, and may be one or three or more. Moreover, a known catalyst can be widely applied to the catalyst 61 .

In general, this type of catalyst has a higher purification performance when it reaches its activation temperature.
In this configuration, since the catalytic converter 52 is arranged at a position close to the power unit 12 serving as a heat source, the heat from the power unit 12 makes it easier for the catalyst 61 to reach the activation temperature.
Moreover, since the inclined surface 63M of the enlarged diameter portion 63 for connecting the catalytic converter 52 and the upstream side exhaust pipe 51 is arranged along the rear wall 12W of the power unit 12, the enlarged diameter portion 63 can be It can be arranged close to the power unit 12 . As a result, catalyst 61 can be warmed up quickly while catalyst converter 52 including enlarged diameter portion 63 is arranged at a higher position than when it is arranged directly under power unit 12 .

In addition, since the catalyst 61 can be arranged at a position away from the exhaust port of the power unit 12, a situation in which the catalyst 61 greatly affects the output characteristics of the power unit 12 can be avoided.
Reference numeral 12M shown in FIG. 4 denotes an engine mount provided on the rear wall 12W of the power unit 12. As shown in FIG. The power unit 12 is supported by the body frame 11 via the engine mount 12M and the like.

As described above, in the saddle-ride type vehicle 1 of the present embodiment, the enlarged diameter portion 63 connecting the catalytic converter 52 to the upstream exhaust pipe 51 is disposed rearwardly and downwardly of the rear wall 12W of the power unit 12, and The inclined surface 63M of the expanded diameter portion 63 is arranged along the rear wall 12W of the power unit 12 when viewed from the side of the vehicle body. With this configuration, as described above, the catalyst 61 can be arranged close to the power unit 12 and the catalyst 61 can be arranged away from the exhaust port of the power unit 12 . Therefore, while facilitating early warm-up of the catalyst 61, the influence on the output characteristics of the power unit 12 is reduced, and the minimum ground clearance is easily ensured.

Further, the upstream exhaust pipe 51 extends rearward from the exhaust port of the power unit 12 through the lower portion of the power unit 12 and the center of the width of the vehicle, and extends to the catalyst 61 . According to this configuration, the exhaust path from the power unit 12 to the catalyst 61 can be easily straightened or moderately shortened while the catalytic converter 52 having the catalyst 61 is arranged at a position that is difficult to see from the outside.

The exhaust device 25 also includes a sub-chamber 53 provided downstream of the catalyst 61 and functioning as an expansion chamber, and a muffler 55 provided downstream of the sub-chamber 53 and functioning as a muffler chamber. At least part of the sub-chamber 53 is positioned below the swing arm 16 and between the power unit 12 and the rear wheel 15 . Furthermore, a portion of the catalyst 61 has entered the sub-chamber 53 . According to this configuration, the space below the swing arm 16 and between the power unit 12 and the rear wheel 15 can be effectively used, making it easier to increase the capacity of the sub-chamber 53 and facilitate the placement of a large-sized catalyst 61. Become.

In addition, a plurality of

catalysts

61A and 61B are provided in the exhaust system 25, and as shown in FIG. big. According to this configuration, the

catalysts

61A and 61B that are long in the front-rear direction can be arranged using the sub-chamber 53 . In other words, the

long catalysts

61A and 61B can be arranged in the front-rear direction without being restricted by the length of the sub-chamber 53 .
The number of

catalysts

61A and 61B may be one, or three or more. Even when a single catalyst 61 is arranged, the long catalyst 61 can be arranged in the front-rear direction without being restricted by the length of the sub-chamber 53 .

Here, the length LB required for arranging the catalyst 61 is the length of the cylindrical body 65 required for supporting the catalyst 61 in this configuration, but is not limited to this. In some cases, it is the total length of the catalyst 61 . For example, if the catalyst 61 is configured by supporting a catalytic material such as platinum, palladium, rhodium, etc. on a punched pipe, the total length of the catalyst 61 can be longer than the sub-chamber 53. is.

As shown in FIGS. 3 and 4, the

catalysts

61A and 61B are arranged along the longitudinal direction of the vehicle body at the center of the vehicle width, and the sub-chamber 53 is formed in a shape that extends laterally beyond the outer cylinder 62. there is According to this configuration, the

catalysts

61A and 61B can be compactly arranged in the vehicle width direction, and it becomes easy to secure the capacity of the sub-chamber 53 while securing the minimum ground clearance.

Further, as shown in FIG. 2, it has a downstream exhaust pipe 54 extending outward in the vehicle width direction from the sub-chamber 53 and connected to a muffler 55, and a connecting portion P2 between the muffler 55 and the downstream exhaust pipe 54 is It is located behind the position P1 of the lower end connecting portion of the rear cushion 37 when viewed from the side of the vehicle body. According to this configuration, it is possible to prevent the muffler 55 from hindering the occupant's ability to put his/her feet on the ground, thereby making it easier to improve the occupant's ability to put the feet on the ground.

It should be noted that the above-described embodiment shows one aspect of the present invention, and the present invention is not limited to the above-described embodiment. For example, although the case where the present invention is applied to the motorcycle shown in FIG. It can be applied to vehicles.

[Configuration supported by the above embodiment]
The above embodiment supports the following configurations.

(Arrangement 1) A straddle-type vehicle comprising an engine supported by a vehicle body frame and an exhaust system connected to the engine and having an exhaust pipe and a catalyst, wherein the catalyst has an outer cylinder having a larger diameter than the exhaust pipe. and the outer cylinder and the exhaust pipe are connected by an enlarged diameter portion that expands toward the outer cylinder, and the rear wall of the engine extends upward or rearward from the rear end of the bottom of the engine Extending, the enlarged diameter portion is positioned rearwardly and downwardly of the rear wall of the engine, and the inclined surface of the enlarged diameter portion extends along the rear wall of the engine as viewed from the side of the vehicle body. A saddle-riding vehicle.
According to this configuration, the catalyst can be arranged close to the engine, and the catalyst can be arranged away from the exhaust port of the engine. And it becomes easy to secure the minimum ground clearance.

(Arrangement 2) The saddle-riding type according to Arrangement 1, wherein the exhaust pipe extends rearward from the exhaust port of the engine through the lower portion of the engine and through the center of the width of the vehicle, and extends to the catalyst. vehicle.
According to this configuration, the exhaust path from the engine to the catalyst can be easily straightened or moderately shortened while arranging the catalyst at a position that is difficult to see from the outside.

(Configuration 3) The exhaust system includes an expansion chamber provided downstream of the catalyst and a silencer chamber provided downstream of the expansion chamber, and at least a portion of the expansion chamber is attached to the vehicle body frame. A structure characterized in that the catalyst is positioned below a swing arm that supports a rear wheel and between the engine and the rear wheel, and that a portion of the catalyst enters the expansion chamber. 3. A straddle-type vehicle according to 1 or 2.
According to this configuration, the space below the swing arm and between the engine and the rear wheels can be effectively used, making it easier to increase the capacity of the expansion chamber and to mount a large catalyst.

(Arrangement 4) Arrangement 3, wherein one or more catalysts are provided in the exhaust system, and the length required for arranging the catalysts is longer than the expansion chamber when viewed from the side of the vehicle body. saddle-type vehicle.
According to this configuration, it is easy to dispose a long catalyst in the front-rear direction without being restricted by the length of the expansion chamber.

(Arrangement 5) The saddle-riding type according to Arrangement 4, wherein the catalyst is arranged along the longitudinal direction of the vehicle body at the center of the width of the vehicle, and the expansion chamber has a shape that expands laterally beyond the outer cylinder. vehicle.
According to this configuration, the catalyst can be compactly arranged in the vehicle width direction, and it becomes easy to secure the capacity of the expansion chamber while securing the minimum ground clearance.

(Arrangement 6) A single rear cushion that reduces impact transmitted from the rear wheel to the vehicle body frame via the swing arm, and a downstream exhaust pipe that extends outward in the vehicle width direction from the expansion chamber and connects to the muffling chamber. 6. Any one of configurations 3 to 5, wherein a connecting portion between the muffling chamber and the downstream side exhaust pipe is positioned rearward of a lower end connecting portion of the rear cushion when viewed from the side of the vehicle body. A saddle-riding vehicle according to the preceding paragraph.
According to this configuration, it is possible to prevent the sound deadening chamber from hindering the occupant's ability to put his feet on the ground, thereby making it easier to improve the occupant's ability to put his feet on the ground.

10 Saddle type vehicle 11 Body frame 12 Power unit (engine)
12S Bottom of power unit 12W Rear wall of power unit 13 Front wheel 15 Rear wheel 16 Swing arm 23 Crankcase 23P Oil pan 24 Cylinder part 25 Exhaust device 37 Rear cushion 51 Upstream exhaust pipe 52 Catalytic converter 53 Sub-chamber (expansion chamber)
54 downstream exhaust pipe 55 muffler (silencing chamber)
61 Catalyst 62 Outer cylinder 63 Expanded diameter portion 63M Inclined surface 65 Cylindrical body

Claims

A straddle-type vehicle comprising an engine (12) supported by a body frame (11) and an exhaust system (25) connected to the engine (12) and having an exhaust pipe (51) and a catalyst (61),
The catalyst (61) is covered with an outer cylinder (62) having a diameter larger than that of the exhaust pipe (51),
The outer cylinder (62) and the exhaust pipe (51) are connected by an enlarged diameter portion (63) that increases in diameter toward the outer cylinder (62),
The rear wall (12W) of the engine (12) extends upward or rearward upward from the rear end of the bottom (12S) of the engine (12),
The enlarged diameter portion (63) is located rearwardly and downwardly of the rear wall (12W) of the engine (12), and the inclined surface (63M) of the enlarged diameter portion (63) is the above-described A straddle-type vehicle characterized by being along the rear wall (12W) of an engine (12).
The exhaust pipe (51) extends rearward from an exhaust port of the engine (12) below the engine (12) and through the center of the width of the vehicle, and extends to the catalyst (61). A straddle-type vehicle according to claim 1.
The exhaust device (25) includes an expansion chamber (53) provided downstream of the catalyst (61) and a silencer chamber (55) provided downstream of the expansion chamber (53),
At least a portion of the expansion chamber (53) is located below a swing arm (16) that is swingable on the vehicle body frame (11) and supports the rear wheel (15), the engine (12) and the rear wheel ( 15) is located between
A straddle-type vehicle according to claim 1 or 2, wherein a portion of said catalyst (61) enters said expansion chamber (53).
one or more catalysts (61) in the exhaust system (25);
A straddle-type vehicle according to claim 3, characterized in that a length (LB) required for disposing the catalyst (61) is longer than the expansion chamber (53) when viewed from the side of the vehicle body.
The catalyst (61) is arranged along the longitudinal direction of the vehicle body at the center of the vehicle width,
The straddle-type vehicle according to claim 4, wherein the expansion chamber (53) has a shape that expands laterally beyond the outer cylinder (62).
a single rear cushion (37) for absorbing impact transmitted from the rear wheel (15) to the body frame (11) through the swing arm (16);
a downstream exhaust pipe (54) extending outward in the vehicle width direction from the expansion chamber (53) and connected to the silencer chamber (55),
A connection portion (P2) between the noise reduction chamber (55) and the downstream exhaust pipe (54) is positioned rearward of a lower end connection portion of the rear cushion (37) as viewed from the side of the vehicle body. A straddle-type vehicle according to any one of claims 3 to 5.