JP2016033015A - Exhaust system of motor cycle - Google Patents

Abstract

An exhaust pipe is compactly provided so as to be wound around a cylinder portion, and a radiator is increased in size so as not to protrude in a vehicle vertical direction. A lower end of the radiator 15 is disposed below the front end of the exhaust pipe 20 in the vehicle vertical direction in a side view, through a space formed behind the radiator 15 and in front of the engine 3. When viewed from the side, the cylinder axis line is L1, the line perpendicular to this forming the lower end of the cylinder block 24 is L2, the alignment line between the cylinder head 25 and the head cover 26 is L3, and the distance between the lines L2 and L3 is the vertical width H of the cylinder. Then, the circumferential portion of the cylinder portion 22 in the exhaust pipe 20 is disposed so as to be within the vertical width H, and the vertical width h of the exhaust pipe 20 in a direction parallel to the cylinder axis L1 in a side view is substantially equal. 1 / 2H. [Selection] Figure 2

Description

The present invention relates to an exhaust device for a motorcycle, and more particularly to a motorcycle having a sufficient exhaust pipe length in a motorcycle (hereinafter, referred to as a rear exhaust type) that exhausts from behind a tilted cylinder provided in an engine. The present invention relates to an exhaust pipe that is arranged around the engine while securing the mass and improves the output of the engine, and also can secure a space for arranging auxiliary equipment around the engine.

In rear exhaust type motorcycles, the distance from the rear of the cylinder to the muffler placement location at the rear of the vehicle must be laid out in a short placement space, so that sufficient exhaust pipe length is gained in such a short placement space. There is a layout in which the exhaust pipe is formed in the shape of a scissor winding below the seat (hereinafter referred to as a “tuna layout”).

JP 2008-207789 A

By the way, in order to concentrate the mass in the motorcycle, there is a demand to arrange not only the exhaust pipe but also other auxiliary machines around the engine arranged in the center of the vehicle. However, since the exhaust pipe is a member having a high temperature, it is difficult to dispose the auxiliary equipment in the vicinity of the periphery of the exhaust pipe. On the other hand, when the exhaust pipe is laid out under the seat as in the above-described conventional example, the auxiliary machine must be arranged in front and back to avoid the exhaust pipe, and the vehicle may be enlarged.
For this reason, when an exhaust pipe and auxiliary equipment are arranged around the engine in a rear exhaust type engine, the auxiliary equipment should be sufficiently separated from the exhaust pipe while maintaining the exhaust pipe length at a predetermined length in order to improve engine output. Securing space for auxiliary equipment that can be placed has been an issue.

In order to solve the above-mentioned problem, the invention described in claim 1 is a motorcycle equipped with a water-cooled engine having a cylinder portion between front and rear wheels and exhausting from an exhaust pipe having one end connected to the cylinder portion. In the exhaust system of
The exhaust pipe has an upstream end connected to the rear side of the cylinder part, extends around the cylinder part and extends to the rear side of the vehicle body,
A radiator (15) is provided in front of the engine (3),
Passing the exhaust pipe (20) behind the radiator (15) and the front of the engine (3);
In a side view, the lower end of the radiator (15) is disposed below the front end of the exhaust pipe (20) in the vehicle vertical direction,
The cylinder part (22) includes a cylinder block (24), a cylinder head (25), and a head cover (26).
In a side view, the cylinder axis (L1), a line (L2) perpendicular to the cylinder block (24) and the lower end of the cylinder block (24), a line of alignment (L3) between the cylinder head (25) and the head cover (26), If the distance between the line (L2) forming the lower end of the cylinder block and the mating line (L3) is the vertical width (H) of the cylinder, the circulation of the cylinder part (22) in the exhaust pipe (20) The part is arranged so as to be within this vertical width (H),
In a side view, the vertical width (h) of the exhaust pipe (20) in a direction parallel to the cylinder axis (L1) is approximately ½ (H).

In the invention described in claim 2, in the above-mentioned claim 1, an air cleaner (42) is disposed between the radiator (15) and the cylinder part (22),
A suction duct (43) provided in the air cleaner (42) protrudes forward of the radiator (15).

According to a third aspect of the present invention, in the second aspect of the invention, the air cleaner (42) is accommodated between the left and right main frames (6) that support the engine (3), and is disposed at an upper end portion of the air cleaner (42). The provided flange (44) overlaps the left and right main frames (6).

According to a fourth aspect of the present invention, in any one of the second or third aspects, a support stay (45) protruding upward from an upper end portion of the radiator (15) passes through the suction duct (43). The protruding end is attached to the main frame (6).

According to a fifth aspect of the present invention, in any one of the third or fourth aspects, the engine hanger (7) is located behind the radiator (15) and in front of the cylinder part (22). It is characterized by extending downward from.

According to a sixth aspect of the present invention, in the fifth aspect, the rear portion of the engine hanger (7) is curved forward, the curved portion of the engine hanger (7), the front surface of the cylinder portion (22), and A space (29) surrounded by an upper front end of the crankcase (23) is provided, and the exhaust pipe (20) is disposed in the space (29).

According to the first aspect of the present invention, since the exhaust pipe is circulated around the cylinder portion, it is not necessary to lay out the seat under the seat in order to secure the exhaust pipe length necessary for obtaining a desired engine output. It is possible to lay out the exhaust pipe in the same way as extending the exhaust pipe forward from the front of the conventional cylinder while earning the exhaust pipe length, and lay out the exhaust pipe around the engine while securing the space for arranging auxiliary equipment. As a result, the increase in size of the vehicle can be suppressed.
In addition, the exhaust pipe can be laid out using the empty space between the engine and the radiator, and passing through the rear of the radiator makes it difficult for the heat from the exhaust pipe to reach the radiator during travel, thereby suppressing the influence on the radiator it can.

Whole side view of motorcycle according to first embodiment. Enlarged side view around the engine according to the first embodiment The principal part top view view of the engine periphery which concerns on 1st Example The principal part perspective view around the engine which concerns on 1st Example The figure corresponding to FIG. 2 which concerns on 2nd Example. The figure corresponding to FIG. 3 which concerns on 2nd Example. Diagram corresponding to FIG. 5 according to the first reference example Diagram corresponding to FIG. 4 according to the first reference example Diagram corresponding to FIG. 7 according to the second reference example Figure corresponding to Figures 3 and 6 for the second reference example The figure corresponding to FIG. 2 which concerns on 3rd Example The figure corresponding to FIG. 3 which concerns on 3rd Example The figure corresponding to FIG. 9 which concerns on a 3rd reference example The figure corresponding to Drawing 10 concerning the 3rd reference example

Embodiments according to the present invention will be described below with reference to the drawings. In the present application, the front / rear, left / right, and upper / lower directions are based on the vehicle to which the present invention is applied.
FIG. 1 is an overall side view of a motorcycle according to a first embodiment. In this motorcycle, an engine 3 is disposed between a front wheel 1 and a rear wheel 2 and supported by a body frame 4. The body frame 4 has a pair of left and right main frames 6 extending from the head pipe 5 obliquely downward and rearward, a pair of left and right engine hangers 7 extending downward and obliquely downward from the head pipe 5 to the main frame 6, and the main frame. A pair of left and right pivot plates 8 extending downward from the rear end of the main frame 6 and a pair of left and right seat rails 9 extending obliquely upward from a seat stay 6a provided at the rear of the main frame 6 and projecting upward. Reference numeral 9 a denotes a back stay that reinforces the seat rail 9.

A pair of left and right front forks 10 that rotatably support the front wheel 1 are rotatably supported at the lower end of the head pipe 5, and the front wheel 1 is steered by a handle 11. The pivot plate 8 supports the pivot shaft 12 so that the front end of the rear swing arm 13 is swingable. The rear wheel 2 is rotatably supported by the rear wheel axle 2a at the rear end of the rear swing arm 13, and the rear swing arm 13 and the seat stay 6a are connected by a shock absorber 14 (an example of an auxiliary machine). Yes.

The engine 3 is a four-cycle water-cooled type and is supported by the main frame 6, the engine hanger 7 and the pivot plate 8. Reference numeral 15 denotes a radiator which is supported in a vertically suspended manner in front of the engine hanger 7. Reference numeral 16 denotes a front fender. A fuel tank 17 is supported on the main frame 6.
Reference numeral 18 denotes a seat, which is supported by the seat rail 9, and a sufficient space for allowing the rear wheel 2 to move up and down is secured between the seat 18 and the engine 3. A rear fender 19 is provided below the seat 18. The rear fender 19 is located above the rear wheel 2 and forms a part (bottom part) of the rear cowl.

20 is an exhaust pipe, and 21 is a muffler (silencer). The muffler 21 is disposed below the seat 18 with its length direction facing front and rear, and the front end overlaps with a seat stay 6a that is the rear of the engine 3 in a side view, and the rear end is rearward of the rear wheel axle 2a at a front position. It partially overlaps with the wheel 2 and contributes to mass concentration by arranging the muffler 21 close to the vicinity of the engine 3.
At the rear end of the muffler 21, an exhaust port 21a (see FIG. 4) is opened rearward and downward to exhaust the vehicle rearward. The position of the exhaust port is set at a position where there is little thermal influence on the rider (not shown) seated on the seat 18, and consideration is given so that heat is not trapped in the space below the seat 18.

2 is an enlarged side view of the engine 3 portion, FIG. 3 is a plan view thereof, and FIG. 4 is a perspective view of the engine and some main peripheral components thereof.
In these drawings, the engine 3 includes a rearwardly inclined cylinder portion 22 and a crankcase 23 that stand up with the upper side slightly inclined rearward in a side view. The cylinder part 22 includes a cylinder block 24, a cylinder head 25, and a head cover 26.
The cylinder head 25 includes an exhaust passage 27 (see FIG. 3) on the rear side. The exhaust upstream end of the exhaust pipe 20 is connected to the exhaust passage 27.

As shown in FIG. 3, the exhaust pipe 20 includes a first rear extension 30, a front extension 31, a lateral extension 32, a second rear extension 33, and a muffler connection 34 in order from the exhaust upstream side. And is wound around the cylinder portion 22 in a plan view in FIG. Strictly speaking, it is not a state in which it makes a complete turn, but this state that is wound so as to make a full turn is called a turn. That is, the exhaust pipe 20 circulates around the cylinder portion 22 in a plan view.
The exhaust pipe 20 is a pipe line connected by connecting a plurality of divided pipes, and the division is appropriately performed from the formability considering the bending of each part.

The first rearward extending portion 30 is a portion disposed on the rear rear side of the cylinder portion 22, and its upstream end is connected to the exhaust passage 27 of the cylinder head 25 and extends rearward along the vehicle body center line C. It is the part that turns back to the front in a substantially U shape. In plan view, it curves convex rearward and extends to the left side of the vehicle body, and curves downward in side view and continues to the front extension 31.

The front extension portion 31 is a portion that extends to the front side of the vehicle body across the left side outer surface of the cylinder portion 22, and the rear half portion continuously protrudes outward in plan view from the first rear extension portion 30. While curving, it extends forward in an open shape, crosses under the left main frame 6 and projects outward from the left main frame 6, and extends laterally at the front left corner of the cylinder portion 22. Continue to 32.
The front extension portion 31 crosses the left side surface of the cylinder block 24 obliquely upward in a side view, and is substantially along the joining line between the upper surface of the crankcase 23 and the cylinder block 24.

The laterally extending portion 32 is a portion that bends from the forwardly extending portion 31 and crosses the front surface of the cylinder portion 22 while curving the front front of the cylinder portion 22 from the left side of the vehicle body to the right side of the vehicle body. Further, it passes below the intake passage 28 protruding forward from the front surface of the cylinder part 22.
The engine hanger 7 extends downward from the main frame 6 behind the radiator 15 and in front of the cylinder part 22, and supports the upper part of the front end of the crankcase 23 at the lower end part. A rear portion of the engine hanger 7 is curved forward, and a space 29 surrounded by the curved portion of the engine hanger 7, the front surface of the cylinder portion 22, and the upper front end of the crankcase 23 is provided. An outlet 32 is provided.

In the plan view of FIG. 3, the laterally extending portion 32 is bent inwardly from the front extending portion 31 and extends obliquely forward, and further bent at a substantially right angle with respect to the vehicle body center line C. Passing below (described below) to the right side of the vehicle.
The right side portion of the laterally extending portion 32 extends while curving forward from below the intake pipe 41 toward the right side of the vehicle body, and overlaps below the right main frame 6 on the right side of the front end portion of the cylinder portion 22. Here, it continues to the upstream end of the second rearward extension 33.

The second rearward extending portion 33 is a portion that bends from the tip of the laterally extending portion 32 and extends rearward substantially linearly across the outer side of the right side surface of the cylinder portion 22. 22 is connected to the muffler connecting portion 34 at the side of the rear end of the right side surface.
The muffler connecting portion 34 bends inward in plan view and extends obliquely rearward, enters the vehicle body inside the right main frame 6, and extends rearward longer than the first rear extending portion 30 to connect to the muffler 21. . The front end position of the muffler 21 is substantially the same as the rear end position of the crankcase 23. In addition, the side view of the muffler connecting portion 34 extends substantially linearly continuously from the second rear extending portion 33 and forms an extension portion of the second rear extending portion 33.

In a side view, the cylinder axis line is L1, the line perpendicular to the cylinder block 24 is L2, the alignment line between the cylinder head 25 and the head cover 26 is L3, and the distance between L2 and L3 is the vertical width of the cylinder. Is H, the surrounding portion of the cylinder portion 22 of the exhaust pipe 20 (the portion including the first rear extension portion 30, the front extension portion 31, the lateral extension portion 32, and the second rear extension portion 33). , It is within this vertical width H.
Further, in a side view of the portion composed of the first rear extension 30 and the front extension 31, the vertical width of the exhaust pipe 20 in the direction parallel to the cylinder axis L1, that is, the first in the direction parallel to the cylinder axis L1. The width h between the uppermost portion of the rear extension 30 and the lowermost portion of the front extension 31 is approximately 1 / 2H.

In this way, the exhaust pipe 20 can be arranged compactly around the cylinder portion 22. In addition, the exhaust pipe 20 can ensure a sufficient exhaust pipe length, and the second rearward extending portion 33 does not bend so much, but extends substantially linearly to the rear to form a substantially linear extension portion. Since it can be connected to the muffler 21 via the connecting portion 34, the piping can be linearly performed below the seat 18.

For this reason, it is not necessary to lay out the bottom of the seat 18 under the seat 18 as in the prior art, and the exhaust pipe length of a sufficient length can be obtained without making a complicated bent shape (circular shape) by rotating the cylinder portion 22. It can be secured.
In addition, since it is not laid out in the space below the seat 18 where heat is likely to be trapped, a sufficient space is secured between the seat 18, the rear fender 19 and the shock absorber 14 and measures against heat damage caused by the exhaust pipe in the tent layout are unnecessary. Thus, the layout of auxiliary equipment such as the shock absorber 14 in the space below the seat 18 can be facilitated. The auxiliary machine is not limited to the shock absorber 14 and includes an auxiliary machine that needs to avoid the influence of the exhaust heat of the exhaust pipe 20.

Further, since the exhaust pipe is not laid out in the space below the seat 18, the muffler 21 can be disposed forwardly in this space and can be disposed close to the cylinder portion 22 of the engine 3, thereby concentrating the mass. In addition, by circulating the exhaust pipe 20 to the cylinder portion 22, the mass can be further concentrated in the vicinity of the engine 3 where the center of gravity of the vehicle body is located. For this reason, the turning performance (turning performance) of the vehicle body can be improved.
In addition, since the exhaust pipe can be laid out in the same way as when the exhaust pipe is extended forward from the front part of the conventional cylinder part, the space around the engine 3 can be secured while securing the space for arranging the shock absorber 14 (auxiliary machine). The exhaust pipe 20 can be centrally laid out, and the shock absorber 14 (auxiliary machine) can be disposed at the front of the vehicle body as compared with the case where the shock absorber is disposed at a predetermined interval for countermeasures against heat behind the hole layout portion. Therefore, it is possible to reduce the size of the vehicle by shortening the front-rear direction of the vehicle body.

Further, as shown in FIG. 2, the laterally extending portion 32 is disposed in the left-right direction below the intake passage 28. A throttle body 40 is attached to the intake passage 28. The throttle body 40 is provided with an intake pipe 41 protruding upward. The intake pipe 41 extends through the throttle body 40 and the lower end opening communicates with the intake passage 28 to form an extension of the intake passage 28.
The intake pipe 41 projects obliquely upward and enters the interior from the back of the air cleaner 42 and opens into a clean room in the air cleaner 42 from which purified air is sucked into the intake passage 28.

Thus, by passing the laterally extending portion 32 of the exhaust pipe 20 between the air cleaner 42 and the cylinder portion 22 and below the intake passage 28, the exhaust pipe 20 can be routed at a position as low as possible. The influence of exhaust heat on the rider can be suppressed.
Further, the exhaust pipe 20 circulates within the vertical width H of the cylinder portion 22, and in particular, circulates around the cylinder head 25 and the cylinder block 24 having the combustion chamber and is warmed by the exhaust pipe 20. You can promote the opportunity.

The air cleaner 42 is disposed between the radiator 15 and the cylinder part 22, and a suction duct 43 provided at the front part protrudes forward on the radiator 15 and protrudes rearward and in the vicinity of the head pipe 5 (see FIG. 2). Outside air that is not affected by the radiator 15 is introduced into the air cleaner 42.
The air cleaner 42 is accommodated between the left and right main frames 6, and a flange 44 provided at the upper end of the air cleaner 42 overlaps the left and right main frames 6, whereby the air cleaner 42 is supported by the left and right main frames 6. ing.

A support stay 45 protruding upward from the upper end portion of the radiator 15 passes through the suction duct 43, and the protruding end portion is attached to the main frame 6.
The radiator 15 is disposed in front of the air cleaner 42 and the cylinder portion 22 so as to be obliquely rearwardly lowered in a side view, and a lower end portion thereof is positioned in the vicinity of an upper portion on the front side of the crankcase 23.

Further, since the radiator 15 is provided in front of the engine 3 and the laterally extending portion 32 of the exhaust pipe 20 is passed to the rear of the radiator 15 and to the front of the engine 3, the exhaust space is exhausted using the empty space between the engine 3 and the radiator 15. The laterally extending portion 32 of the pipe 20 can be laid out, and since the heat from the exhaust pipe 20 does not easily reach the radiator 15 when traveling by passing behind the radiator 15, the influence on the radiator 15 can be suppressed.

Next, a second embodiment will be described with reference to FIGS. In this example, the laterally extending portion 32 is divided from the previous embodiment, and FIG. 5 corresponds to FIG. 2 and FIG. 6 corresponds to FIG. Note that common parts are denoted by common reference numerals, and redundant description is omitted (the same applies to the following examples and reference examples).
In this example, the intermediate portion in the longitudinal direction of the laterally extending portion 32 is divided into a left portion 51 and a right portion 52 by the dividing portion 50, and the joining flanges 53 and 54 provided at the respective opposing end portions are combined to form a bolt. By being fastened with the nut 55 and the nut 56, continuous integration is achieved.

The exhaust pipe 20 is divided into a left half 20L from the first rear extension 30 to the left part 51 and a right half 20R from the right part 52 to the muffler connection part 34 by the dividing part 50 (FIG. 6). reference).
The left half portion 20L and the right half portion 20R may be configured such that each length direction is further divided into a plurality of portions and connected. Of course, the left half 20L and the right half 20R may each have a single tube configuration.

Thus, by dividing the laterally extending portion 32 into left and right, the assembly becomes easy, and the maintenance can be improved because it can be easily divided and removed during maintenance.
Further, since the tightly bent portion is divided, the exhaust pipe 20 can be easily formed, and the left half 20L and the right half 20R can be easily formed as a single pipe.
Furthermore, the same effect as the previous embodiment can be enjoyed.

Next, a first reference example will be described with reference to FIGS. In this example, the length of the exhaust pipe is made longer than in the previous embodiments, and the layout position of the laterally extending portion 32 is also lower than in the previous embodiments.
The front extension part 31 is bent in a substantially U shape in a side view (FIG. 7), and has bending points P1, P2, and P3 in order from the upstream side.
The bending point P1 is in the vicinity of the rear portion of the left side surface of the cylinder block 24, which is in the vicinity of the connection portion with the first rearward extension portion 30.
The bending point P2 is an intermediate portion in the longitudinal direction of the front extending portion 31 and is near the front upper portion of the crankcase 23. The bending point P2 is bent from here and extends downward at a steep angle.
The bending point P3 is in the vicinity of the lower end on the front side of the crankcase 23, from which the laterally extending portion 32 bends downward and inward of the vehicle body.

The forward extension portion 31 forms an upstream portion 31A and a downstream portion 31B across the bending point P2.
The upstream portion 31A is a portion between the bending points P1 and P2, and the downstream portion 31B is a portion between the bending points P2 and P3. The upstream part 31A and the downstream part 31B form a continuous single pipe.
The upstream portion 31A has a gentler inclination than the downstream portion 31B and obliquely crosses the upper left side surface of the cylinder block 24 and the crankcase 23.
The downstream portion 31B has a steeper slope than the upstream portion 31A, and extends downward in front of the front surface 23a of the crankcase 23.
The front surface 23a has a vertical standing wall shape, and by forming a space in front of this, the downstream portion 31B and the laterally extending portion 32 are easily laid out.

The laterally extending portion 32 extends in the left-right direction while convexly curving downward so that the middle portion in the left-right direction is the lowest. The lowermost portion of the laterally extending portion 32 projects downward from the lowermost end portion 23b of the front surface 23a. The bending point P <b> 2 is located near the lower end of the radiator 15, and most of the downstream portion 31 </ b> B and the laterally extending portion 32 are located below the lower end of the radiator 15.
Further, the lower part of the laterally extending part 32 may be provided with a divided part similar to the previous example, and may be joined by the joining flanges 53 and 54. The effect of facilitating attachment and maintenance can be expected.

The second rearward extending portion 33 has a substantially U-shape similar to that of the frontward extending portion 31 and is formed longer. From the vicinity of the lowermost end portion 23b of the front surface 23a upward, the crankcase 23 and the cylinder portion 22 are formed. Is crossed diagonally from the lower front to the rear upper. In this way, the exhaust pipe length can be made sufficiently longer than in the previous embodiments.

Further, the laterally extending portion 32 is piped using a space below the lower end portion of the radiator 15 and in front of the front surface 23a. In this way, the exhaust pipe 20 can be routed and laid out by effectively utilizing the empty space below the radiator 15 and in front of the crankcase 23, and most of the exhaust pipe 20 that is relatively high in temperature is disposed in the radiator 15. Since the dead space is effectively used, the heat of the exhaust pipe 20 can be made difficult to reach the radiator 15, and the influence of the exhaust heat on the radiator 15 can be suppressed.

Further, although not shown, the exhaust pipe 20 is configured to circulate around the cylinder portion 22 in a plan view, as in the previous embodiments. Therefore, it is possible to enjoy the same effects as those of the preceding embodiments, such as ensuring a sufficient exhaust pipe length and mass concentration, while avoiding complicated bending and securing an auxiliary machine arrangement space based on this circuit configuration.

Next, a second reference example will be described based on FIGS. 9 corresponds to FIG. 7, and FIG. 10 corresponds to FIG. In this example, an expansion chamber 60 composed of a large-diameter cylindrical chamber or the like is provided in the laterally extending portion 32 with respect to the exhaust pipe 20 of the previous reference example.
The expansion chamber 60 is a catalyst chamber or a sub-muffler chamber, has a cylindrical shape larger than the lateral extension portion 32, and is disposed in front of the crankcase 23 and below the lower end portion of the radiator 15 with the length direction directed to the left and right. Is done. In addition, the shape of the expansion chamber 60 is free, and a chamber structure in which the volume of not only a cylindrical shape but also a rectangular tube shape or the like is expanded is possible.

The laterally extending portion 32 is composed of a short left portion 61 and a right portion 62 that are divided into left and right with the middle portion cut away by the length of the expansion chamber 60 (see FIG. 10), and each end portion is enlarged. Connect to the left and right ends of the chamber 60. However, the lateral extension portion 32 may be omitted, and the downstream end portion of the downstream portion 31B and the upstream end portion of the second rear extension portion 33 may be directly connected to the expansion chamber 60, respectively.

The expansion chamber 60 functions as a catalyst chamber by disposing the catalyst therein, and the exhaust gas flowing from the first rear extension 30 and the front extension 31 is purified here, and the second rear extension 33 To the muffler 21. Further, since the expansion chamber 60 has a large-diameter cylindrical shape with respect to the front and rear exhaust pipe 20 portions, a large-capacity space is formed therein. Exhaust energy can be reduced by expanding the exhaust from the front extending portion 31. Therefore, the expansion chamber 60 can function as a sub-muffler chamber for the muffler 21.

Thus, by providing the large-diameter enlarged chamber 60 in the laterally extending portion 32, it can be used as a catalyst chamber or a sub-muffler chamber that requires a large capacity. In addition, these catalyst chambers and sub-muffler chambers are both large-sized ones that require a relatively large capacity, but by comparing them by laying out the front part of the crankcase 23 where a relatively large space is easily secured. The large catalyst chamber or sub-muffler chamber can be efficiently laid out, and the size of the motorcycle can be suppressed.

Further, by disposing the expansion chamber 60 below the radiator and in front of the engine, it is possible to prevent interference with the radiator and to efficiently use the empty space and to efficiently arrange the space. In addition, the effects of the previous reference example such as suppressing the thermal influence of the exhaust pipe 20 on the radiator 15 can also be enjoyed.

Next, a third embodiment will be described with reference to FIGS. In this example, a dividing portion is provided for the exhaust pipe 20 of the first embodiment. FIG. 11 corresponds to FIG. 2 and FIG. 12 corresponds to FIG. 3, and only the points where the exhaust pipe is provided with a dividing portion are changed.
In this example, the exhaust pipe 20 is divided on the left and right sides of the cylinder portion 22. On the left side of the vehicle body, the downstream end of the first rear extension 30 and the upstream end of the front extension 31 are coupled to the rear side of the cylinder 22. This coupling is the same as that of the second embodiment (FIGS. 5 and 6), and the joining flanges provided at the opposing end portions in the split portion 50A of the first rear extension portion 30 and the front extension portion 31. By combining 53 and 54 and fastening them with bolts 55 and nuts 56, they are detachably coupled. If the first rear extension 30 and the front extension 31 are divided, the first rear extension 30 with a tight bend can be manufactured separately from the front extension 31, which is advantageous in manufacturing. Similarly, the laterally extending portion 32 having a tight bend may be divided and coupled to the forward extending portion 31.

On the right side of the vehicle body, the second rearward extending portion 33 is divided into a front portion 33A and a rear portion 33B by a split portion 50B, and joint flanges 53 and 54 provided at respective end portions facing each other at the split portion 50B are combined as in the left side. The bolts 55 and the nuts 56 are connected so as to be separable. This connecting portion is a tightly bent portion in the second rearward extending portion 33, and is near the front right corner portion of the cylinder portion 22. If it does in this way, since the 2nd back extension part 33 with comparatively bend | curve can be divided | segmented into the front part 33A and the rear part 33B, and it can manufacture separately, respectively, manufacture becomes easy.
In addition, you may couple | bond together so that a division | segmentation part may be provided between the 2nd back extension part 33 and the muffler connection part 34, and to be separable.

As described above, by providing the exhaust pipe 20 with the divided structure on the side of the engine 3 (cylinder portion 22), it is easy to assemble and remove, so that maintainability is improved. The divided structure may be at least one of the left and right sides of the engine 3 around which the exhaust pipe 20 circulates, and the number thereof may be one or more.

Next, a third reference example will be described with reference to FIGS. In this example, a dividing portion is provided with respect to the exhaust pipe of the second reference example. FIG. 13 corresponds to FIG. 9 and FIG. 14 corresponds to FIG. It is.
That is, the left portion 61 and the right portion 62 that are formed with the laterally extending portion 32 and sandwiching the expansion chamber 60 that is the catalyst chamber or the sub-muffler chamber are respectively connected to the front extending portion 31 and the second rear extending portion 33. It is a separable combination. A split portion 50C is provided between the left portion 61 and the front extending portion 31, and the joining flanges 53 and 54 provided at the opposing ends are combined and fastened with bolts 55 and nuts 56, whereby the expansion chamber 60 is provided. It is separably connected on the left side of.
The right portion 62 is provided with a split portion 50D between the second rearward extending portion 33, and is joined by fastening the joint flanges 53, 54 provided at the opposite end portions with bolts 55 and nuts 56, thereby expanding the right portion 62. It is connected to the right side of the chamber 60 in a separable manner.

In this way, in the vicinity of the left and right sides of the expansion chamber 60, the left portion 61 and the front extension portion 31, and the right portion 62 and the second rear extension portion 33 are separated, so that the expansion chamber 60 and the engine 3 are separated. The other part of the exhaust pipe 20 that circulates can be easily separated to facilitate assembly, and the ease of removal improves maintenance. In addition, it is free to combine the structure which divides | segments the front extension part 31 and the 2nd back extension part 33 in a previous Example by the side of the engine 3. FIG.
The present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the invention described in the claims.

3: engine, 15: radiator, 20: exhaust pipe, 21: muffler, 22: cylinder part, 23: crankcase, 24: cylinder block, 25: cylinder head, 26: head cover, 27: exhaust passage, 28: intake passage , 30: first rear extension part, 31: front extension part, 32: lateral extension part, 33: second rear extension part, 50: division part, 51: left part, 52: right part, 60: Cylindrical chamber

Claims (6)

An exhaust system for a motorcycle equipped with a water-cooled engine (3) having a cylinder part (22) between the front and rear wheels and exhausting from an exhaust pipe (20) having one end connected to the cylinder part (22). In
The exhaust pipe (20) has an upstream end connected to the vehicle rear side of the cylinder part (22), circulates around the cylinder part (22) and extends to the vehicle body rear side,
A radiator (15) is provided in front of the engine (3),
Passing the exhaust pipe (20) behind the radiator (15) and the front of the engine (3);
In a side view, the lower end of the radiator (15) is disposed below the front end of the exhaust pipe (20) in the vehicle vertical direction,
The cylinder part (22) includes a cylinder block (24), a cylinder head (25), and a head cover (26).
In a side view, the cylinder axis (L1), a line (L2) perpendicular to the cylinder block (24) and the lower end of the cylinder block (24), a line of alignment (L3) between the cylinder head (25) and the head cover (26), If the distance between the line (L2) forming the lower end of the cylinder block and the mating line (L3) is the vertical width (H) of the cylinder, the circulation of the cylinder part (22) in the exhaust pipe (20) The part is arranged so as to be within this vertical width (H),
The exhaust of a motorcycle, characterized in that, in a side view, the vertical width (h) of the exhaust pipe (20) in a direction parallel to the cylinder axis (L1) is approximately 1/2 (H). apparatus. An air cleaner (42) is disposed between the radiator (15) and the cylinder part (22);
The exhaust system for a motorcycle according to claim 1, wherein a suction duct (43) provided in the air cleaner (42) protrudes forward of the radiator (15). The air cleaner (42) is accommodated between left and right main frames (6) that support the engine (3), and a flange (44) provided at an upper end of the air cleaner (42) is provided on the left and right main frames (6). The exhaust device for a motorcycle according to claim 2, wherein the exhaust device overlaps with the motorcycle. A support stay (45) protruding upward from the upper end of the radiator (15) passes through the suction duct (43), and the protruding end is attached to the main frame (6). The exhaust device for a motorcycle according to any one of 2 and 3. An engine hanger (7) extends downward from the main frame (6) behind the radiator (15) and in front of the cylinder part (22). The motorcycle exhaust apparatus described. The rear portion of the engine hanger (7) is curved forward, and is a space surrounded by the curved portion of the engine hanger (7), the front surface of the cylinder portion (22), and the upper front end of the crankcase (23) ( 29. The exhaust system for a motorcycle according to claim 5, wherein 29) is provided, and the exhaust pipe (20) is disposed in the space (29).

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