WO2019043869A1

WO2019043869A1 - Exhaust device for saddled vehicles

Info

Publication number: WO2019043869A1
Application number: PCT/JP2017/031360
Authority: WO
Inventors: 弘志間平
Original assignee: 本田技研工業株式会社
Priority date: 2017-08-31
Filing date: 2017-08-31
Publication date: 2019-03-07

Abstract

This exhaust device for saddled vehicles comprises: a catalyst that cleans exhaust gas discharged from an engine; a muffler chamber that muffles the exhaust noise of the engine downstream of the catalyst; an exhaust introduction pipe that has one end connected to an exhaust passage connected to the exhaust port of the engine and the other end projecting into the muffler chamber; and a downstream oxygen sensor that detects the oxygen concentration of the exhaust gas which passed through the catalyst. The bottom wall of the muffler chamber is surrounded on three sides by side walls and has a recessed part open at the top and on one side. The bottom wall of the recessed part declines toward the one side, the decline ending at the edge of the one side. The downstream oxygen sensor piercingly extends through the bottom wall of the recessed part and the exhaust introduction pipe and is attached to the recessed part. The oxygen detection unit of the downstream oxygen sensor is disposed so as to overlook a point along the exhaust introduction pipe which is downstream of the catalyst.

Description

Exhaust system for straddle-type vehicles

The present invention relates to an exhaust system for a saddle-ride type vehicle.

In a saddle-ride type vehicle such as a motorcycle, an exhaust passage is connected to an exhaust port of an engine, and an exhaust purification catalyst and a muffling chamber are connected to the exhaust passage. Upstream from the catalyst in the exhaust passage, an upstream oxygen sensor for detecting the oxygen concentration of the exhaust gas before passing through the catalyst is installed. The detection signal of the upstream oxygen sensor is output to the controller. The controller appropriately controls the air fuel ratio of the engine in response to the detection signal.

Further, in recent years, as an exhaust system of a saddle-ride type vehicle, one equipped with a downstream side oxygen sensor for detecting the oxygen concentration of exhaust gas which has passed through the catalyst has been developed separately from the upstream side oxygen sensor. The signal detected by the downstream oxygen sensor is output to the controller. The controller receives the detection signal to determine the state of the catalyst and the like.

As an exhaust device of this type, a catalyst is disposed inside the exhaust pipe and the muffling chamber on the upstream side of the muffling chamber, and is connected downstream to the connecting pipe that connects the muffling chamber and the main muffler on the downstream side of the muffling chamber. It is known that an oxygen sensor is installed.

However, in this exhaust system, since the detection of the oxygen concentration by the downstream oxygen sensor is performed on the downstream side of the muffling chamber, the oxygen concentration of the exhaust gas staying in the muffling chamber is detected by the downstream oxygen sensor Potential. Therefore, it is desirable to more accurately detect the oxygen concentration of the exhaust gas immediately after passing through the catalyst.

As another exhaust system, a depression is provided on the upper wall of the muffling chamber, and a downstream oxygen sensor is installed on the bottom wall of the depression so as to reach the inside of the exhaust introduction pipe in the muffling chamber. It has been issued. In this exhaust system, the catalyst is disposed on the upstream side of the exhaust gas introduction pipe, and the downstream oxygen sensor can detect the oxygen concentration of the exhaust gas immediately after passing through the catalyst.

However, in this exhaust system, since the depression for installing the downstream oxygen sensor is provided on the upper wall of the muffling chamber, there is a concern that foreign matter such as water droplets may stay in the depression on the muffling chamber. Ru.

Japanese Patent Application Publication No. 2007-8442 International Publication No. 2017/104098

Therefore, the present invention provides an exhaust system for a saddle-ride type vehicle, which can accurately detect the oxygen concentration of exhaust gas immediately after passing through a catalyst by means of the downstream oxygen sensor and can suitably arrange the downstream oxygen sensor. It is something to try.

The present invention comprises a catalyst (42) for purifying exhaust gas discharged from an engine (22), a muffling chamber (37) for muffling exhaust noise of the engine (22) downstream of the catalyst (42), and one end Are connected to the exhaust passage (36) connected to the exhaust port (35) of the engine (22), and the other end of the exhaust introduction pipe (43L, 43R) protrudes into the muffling chamber (37); (42) In the exhaust system of a saddle-ride type vehicle provided with a downstream oxygen sensor (48) for detecting the oxygen concentration of the exhaust gas, the muffling chamber (37) has a periphery of the bottom wall (47a) The bottom wall (47a) of the recess (47) has a recess (47) surrounded on three sides by a side wall (47b) and opened upward and on one side, and the bottom wall (47a) of the recess (47) extends downward toward the one side. Tip to the side edge The downstream oxygen sensor (48) is attached to the recess (47) by penetrating the bottom wall (47a) of the recess (47) and the exhaust introduction pipe (43L, 43R), and the downstream side The oxygen detection portion (48a) of the oxygen sensor (48) is characterized in that it is disposed to face the downstream position of the catalyst (42) in the exhaust gas introduction pipe (43L, 43R).

According to the above configuration, the oxygen detection unit (48a) of the downstream side oxygen sensor (48) is disposed in the exhaust gas introduction pipe (43L, 43R). Therefore, the oxygen concentration of the exhaust gas immediately after passing through the catalyst (42) can be accurately detected by the downstream oxygen sensor (48). The downstream oxygen sensor (48) is attached to the recess (47) by penetrating the bottom wall (47a) of the recess (47) of the muffling chamber (37) and the exhaust introduction pipes (43L, 43R). The downstream oxygen sensor (48) can be stably installed while suppressing an increase in the number of points. In addition, the bottom wall (47a) of the recess (47) provided in the muffling chamber (37) is inclined downward to one side toward the open side to the one side end, so the recess (47) Foreign particles such as water droplets that have flowed into) can be suppressed from remaining in the recess (47). Furthermore, the entire upper wall of the muffling chamber (37) is lowered so that the mounting portion of the downstream oxygen sensor (48) is not close to the exhaust gas introduction pipe (43L, 43R), but the recess (47) in the muffling chamber (37) And the downstream oxygen sensor (48) is attached to the bottom wall (47a) of the recess (47), so that the internal volume of the muffling chamber (37) can be sufficiently secured in portions other than the recess (47). it can. In addition, since the recess (47) surrounded on three sides by the side wall (47b) is formed in the muffling chamber (37), at the time of thermal expansion of the muffling chamber (37), the three side walls (47b) of the recess (47) By expanding and contracting in the vertical direction, it is possible to suppress the thermal expansion in the direction along the extending direction of the exhaust introduction pipe (43L, 43R) of the muffling chamber (37). Further, since the muffling chamber (37) is downstream of the catalyst (42) and there is no catalyst (42) in the muffling chamber (37), a large internal volume for muffling of the muffling chamber (37) is secured. be able to.

The muffling chamber (37) is formed in a substantially flat cross-sectional shape having a horizontally long cross section substantially orthogonal to the extending direction of the exhaust introduction pipe (43L, 43R), and the exhaust introduction pipe (43L, 43R) and the recess (47) and the downstream side oxygen sensors (48) may be arranged two by two in the left and right symmetry in the muffling chamber (37).

In this case, since the muffling chamber (37) is formed in a horizontally long, substantially flat cross-sectional shape, the height of the muffling chamber (37) can be reduced while securing the internal volume for muffling. Therefore, when this configuration is adopted, it is advantageous for suppressing the occupied height of the muffling chamber (37) in the vehicle in the vertical direction. Further, in this case, the shape of the muffling chamber (37) and the arrangement of the exhaust introduction pipes (43L, 43R) and the downstream oxygen sensor (48) are symmetrical in the left-right direction. Measures can be taken advantageously. Further, since the shape of the muffling chamber (37) and the arrangement of the exhaust introduction pipes (43L, 43R) and the downstream oxygen sensor (48) are symmetrical, the deformation behavior of the muffling chamber (37) during thermal expansion is also possible. It becomes the same on both sides and becomes stable.

Joining pipes (41L, 41R) in which a plurality of exhaust pipes (40La, 40Lb, 40Ra, 40Rb) are joined and connected are respectively connected to the two exhaust introducing pipes (43L, 43R), and the respective joining pipes (41L, 41R) An upstream oxygen sensor (46) for detecting the oxygen concentration of the exhaust gas before passing through the catalyst (42) is attached to 41R), and the two upstream oxygen sensors (46) And the muffling chamber (37) are disposed behind the oil pan (28), and the two downstream oxygen sensors (48) are It may be arranged at the inside position in the vehicle width direction overlapping the oil pan (28).

In this case, the upstream oxygen sensor (46), whose upward protruding height from the junction pipe (41L, 41R) is high, is disposed on the left and right sides of the oil pan (28). The height above the ground of the left and right combined pipes (41L, 41R) can be increased without causing the interference between the upper part of the upper part and the oil pan (28). In addition, the muffling chamber (37) is disposed behind the oil pan (28), and the two downstream oxygen sensors (48) are disposed at an inner position in the vehicle width direction overlapping the oil pan (28) in the front-rear direction. Therefore, the left and right combined pipes (41L, 41R) can be moved to the inner side in the vehicle width direction and connected to the muffling chamber (37). Therefore, when this configuration is adopted, the lateral extension width of the connection portion of the muffling chamber (37) and the left and right joining pipes (41L, 41R) is increased while raising the height of the muffling chamber (37) above the ground. Since it can be narrowed, it becomes easy to secure a large bank angle of the vehicle.

The exhaust introduction pipe (43L, 43R) extends from the vehicle front side toward the vehicle rear side, and the center of the flow of exhaust gas flowing from the exhaust introduction pipe (43L, 43R) into the muffling chamber (37) It is provided in the muffling chamber (37) so that the axis (o1) is above the central axis (o3) of the flow of exhaust gas passing through the catalyst (42), and the bottom of the muffling chamber (37) The wall (37b) may be inclined upward toward the rear of the vehicle body.

In this case, the portion where the exhaust gas flows into the muffling chamber (37) of the exhaust introduction pipe (43L, 43R) is offset above the portion where the catalyst (42) is disposed, so the offset thereof In part, the bottom wall (37b) of the muffling chamber (37) can be above the bottom surface of the catalyst (42). Furthermore, in addition to this, the bottom wall (37b) of the muffling chamber (37) is inclined upward toward the rear of the vehicle body. Therefore, when this configuration is adopted, the space between the rear area of the bottom wall (37b) of the muffling chamber (37) and the road surface can be easily secured at the rear of the vehicle body where the distance to the road surface is required. .

Connected to the muffling chamber (37) is a connecting pipe (44) for leading the exhaust gas flowing into the muffling chamber (37) from the exhaust introduction pipe (43L, 43R) to the main muffler (38), and the connection The pipe (44) has a central axis (o1) of the flow of exhaust gas, the center (o2) of the connection to the muffling chamber (37) flowing from the exhaust gas introducing pipe (43L, 43R) into the muffling chamber (37). It may be connected to the muffling chamber (37) so as to be at a higher position than that.

In this case, since the connecting pipe (44) that easily vibrates when the vehicle travels is connected to the upper region of the muffling chamber (37), the distance between the connecting pipe (44) and the road surface can be easily secured during turning of the vehicle. can do. Therefore, when this configuration is adopted, it is possible to secure a large bank angle of the vehicle.

The recess (47) may be disposed at a substantially central position in the extending direction of the exhaust introduction pipe (43L, 43R) in the muffling chamber (37).

In this case, it is possible to prevent generation of abnormal noise (squeal) in the muffling chamber (37) while keeping the strength of the muffling chamber (37) well-balanced in the front-rear direction by the concave part (47).

The downstream oxygen sensor (48) may be surrounded by the side wall (47b) of the muffling chamber (37) in a range of one third or more in the height direction.

In this case, since the range of 1/3 or more of the height direction of the downstream oxygen sensor (48) is surrounded by the side wall (47b), the downstream oxygen sensor (48) is formed by the side wall (47b) of the recess (47) It can be advantageously protected from the outside.

A side stand (60) of the vehicle is attached to the vehicle body frame (F) so that it can pivot up and down, and the downstream oxygen sensor (48) is outside in the vehicle width direction by the side stand (60) in the bounce up position. It may be arranged at a position where at least a part is covered.

In this case, since the outside in the vehicle width direction of the downstream oxygen sensor (48) is covered by the side stand (60) at the flip-up position, the downstream oxygen sensor (48) is externally driven by the side stand (60) Can be protected.

In the exhaust system of the saddle-ride type vehicle according to the present invention, the downstream oxygen sensor is attached to the bottom wall of the recess of the muffling chamber, and the downstream oxygen sensor detection unit is disposed facing the downstream position of the catalyst in the exhaust introduction pipe Therefore, the oxygen concentration of the exhaust gas immediately after passing through the catalyst can be accurately detected by the downstream oxygen sensor.
Further, in the exhaust system of the saddle-ride type vehicle according to the present invention, since the bottom wall of the recess of the muffling chamber is inclined downward to one side, it is possible to suppress the retention of foreign matter such as water droplets on the recess. it can.

1 is a side view of a saddle-ride type vehicle according to an embodiment of the present invention. 1 is a front view of a portion of a saddle-ride type vehicle according to an embodiment of the present invention. It is a top view of the exhaust system and side step of an embodiment of the present invention. 1 is a bottom view of a part of a saddle-ride type vehicle according to an embodiment of the present invention. 1 is a side view of a part of a saddle-ride type vehicle according to an embodiment of the present invention. FIG. 1 is a rear view of a part of a saddle-ride type vehicle according to an embodiment of the present invention. It is a perspective view of the exhaust system of an embodiment of the present invention. It is a side view of the exhaust system of the embodiment of the present invention. FIG. 9 is a cross-sectional view of the exhaust system of the embodiment of the present invention taken along line IX-IX of FIG. 7; 1 is a side view of a part of a saddle-ride type vehicle according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, front and rear, upper and lower, and left and right mean front and rear, upper and lower, and left and right of the vehicle unless otherwise specified. Further, arrow FR in the figure points to the front of the vehicle, arrow UP points to the upper side of the vehicle, and arrow LH points to the left of the vehicle.

FIG. 1 is a left side view of a motorcycle 1 which is an embodiment of a saddle-ride type vehicle.
A steering stem (not shown) is rotatably supported by the head pipe 10 at the front of the vehicle body frame F of the motorcycle 1. The steering stem holds a pair of left and right front forks 13 via the top bridge 11 and the bottom bridge 12. A front wheel Wf is rotatably supported at the lower ends of the left and right front forks 13. A steering handle 14 is attached to the top of the top bridge 11.

The body frame F includes the head pipe 10, a pair of left and right main frames 15 extending obliquely downward from the top of the head pipe 10, a pair of left and right center frames 16 extending downward from the rear of the main frame 15, and the head pipe 10 A pair of left and right auxiliary frames 17 connecting the lower part of the main frame 15 and a pair of left and right down frames 18 extending downward from each auxiliary frame 17 and bent backward and extending substantially horizontally and connected to the lower end of the center frame 16; And. The body frame F further includes a pair of left and right seat frames (not shown) extending rearward from the upper ends of the left and right center frames 16 and a seat frame corresponding to a substantially central portion of the left and right center frames 16 in the vertical direction. And a pair of left and right rear frames 19 connecting the substantially central portion.

A fuel tank 20 is mounted on the upper side of the main frame 15, and a seat 21 for seating an occupant is mounted on a seat frame at the rear of the fuel tank 20. A power unit PU including an engine 22 and a transmission (not shown) is disposed in an area surrounded by the down frame 18 and the center frame 16 below the main frame 15. The power unit PU is attached to the left and right down frames 18 and the center frame 16 via a bracket, a stay, and the like.
In the rear area of the left down frame 18, a side stand 60 of the vehicle is attached so as to be pivotable.

The front end portions of the swing arms 23 are supported swingably in the vertical direction on the left and right center frames 16. At the rear of the swing arm 23, an axle 24 of the rear wheel Wr is rotatably supported. An output shaft (not shown) of the power unit PU and an axle 24 of the rear wheel Wr are linked in a power transmittable manner via a drive chain 25. The rear portion of the swing arm 23 is supported by the vehicle body frame F via the cushion unit 26.

Further, the engine 22 is an in-line four-cylinder four-stroke engine, and a transmission is housed at the rear in the crankcase 27. A cylinder portion 31 including a cylinder block 29 and a cylinder head 30 is attached to a front upper portion of the crankcase 27 with a slight front inclination. Further, an oil pan 28 for storing lubricating oil is attached to the lower surface of the crankcase 27.

An intake port (not shown) of each cylinder is provided on the rear surface side of the cylinder head 30, and an intake device 34 including a throttle body 32 and an air cleaner 33 is connected to the intake port.
Further, an exhaust port 35 of each cylinder is provided on the front side of the cylinder head 30, and an exhaust device 39 including an exhaust passage 36, a muffling chamber 37 and a main muffler 38 is connected to each exhaust port 35. .

FIG. 2 is a view of the power unit PU and the exhaust system 39 as viewed from the front of the vehicle. FIG. 3 is a view of the exhaust system 39 and the side stand 60 as viewed from above the vehicle, and FIG. 4 is a view of the rear area of the power unit PU and the exhaust system 39 as viewed from below the vehicle. 5 is a left side view of the exhaust device 39 and the rear area of the power unit PU, and FIG. 6 is a rear view of the power unit PU and the exhaust device 39. As shown in FIG.
The exhaust passage 36 includes four exhaust pipes 40La, 40Lb, 40Ra, and 40Rb connected to the exhaust ports 35 of the cylinders of the engine 22, and a left joining pipe 41L joining and connecting the two left exhaust pipes 40La and 40Lb. , And a right merging pipe 41R connecting the right two exhaust pipes 40Ra and 40Rb by merging. The left and right merging

pipes

41L and 41R are connected to the front of the muffling chamber 37 in left-right symmetry. Further, a catalyst 42 for purifying the exhaust gas discharged from the engine 22 through the exhaust pipes 40La, 40Lb, 40Ra and 40Rb is internally provided in the merging

pipes

41L and 41R. Therefore, the muffling chamber 37 muffles the exhaust noise of the engine 22 downstream of the catalyst 42. In the case of this embodiment, since the muffling chamber 37 is downstream of the catalyst 42 and there is no catalyst 42 in the muffling chamber 37, a large internal volume for muffling of the muffling chamber 37 can be secured.

The muffling chamber 37 is formed in a slightly rounded substantially rectangular shape, and the inside thereof is a muffling chamber. On the front wall of the muffling chamber 37, a pair of left and right

exhaust introduction pipes

43L, 43R projecting into the muffling chamber 37 are attached. The left and right

exhaust introduction pipes

43L, 43R are connected to the corresponding left and right merging

pipes

41L, 41R, and extend substantially in the longitudinal direction of the vehicle body in the muffling chamber 37. The left and right

exhaust introduction pipes

43L, 43R are disposed symmetrically inside the muffling chamber 37, and the tip end portion thereof extends to the vicinity of the rear wall 37r of the muffling chamber 37. Further, a connection pipe 44 connecting the muffling chamber 37 and the main muffler 38 is connected to a rear position of the right side wall of the muffling chamber 37. The connecting pipe 44 extends obliquely from the right side wall of the muffling chamber 37 to the rear upper side. The main muffler 38 is connected to the rear upper side of the connection pipe 44. The connection pipe 44 guides the exhaust gas, which has flowed into the muffling chamber 37 from the

exhaust introduction pipes

43L and 43R, to the main muffler 38.

As shown in FIG. 5, the bottom wall 37b of the muffling chamber 37 is directed from the front end to which the

exhaust introduction pipes

43L and 43R are connected toward the rear wall 37r (rear of the vehicle) (to the side where the connection pipe 44 is connected). Tilt upwards). Further, the left and right

exhaust introduction pipes

43L, 43R extend from a substantially central position in the height direction of the front wall of the muffling chamber 37 toward the rear side of the vehicle body.

Here, the left and right

exhaust introduction pipes

43L, 43R are a downstream pipe portion 43a opened in the muffling chamber 37, and an upstream pipe portion 43b connecting the downstream pipe portion 43a and the corresponding left and right joining

pipes

41L, 41R, have. The upstream pipe portion 43b is gradually reduced in diameter from the base side connected to the merging

pipes

41L and 41R toward the tip end side (downstream side), and the axial center portion is gradually offset upward. Therefore, the central axis o1 of the flow of exhaust gas flowing from the downstream pipe portion 43a into the muffling chamber 37 is offset above the central axis o3 of the flow of exhaust gas passing through the catalyst 42 in the merging

pipes

41L and 41R. There is.

Further, as shown in FIG. 5, in the connection pipe 44, the central axis of the flow of exhaust gas in which the center o2 of the connection portion to the muffling chamber 37 flows from the

exhaust introduction pipes

43L and 43R (downstream pipe part 43a) It is connected to the muffling chamber 37 so as to be positioned above o1.

As shown in FIG. 4, the bottom wall 28a of the oil pan 28 is formed at the lowest position in the central region in the vehicle width direction, and the left and right side walls 28l and 28r connected to the bottom wall 28a are formed obliquely in the upward direction. . An oil element 45 is attached substantially at the center of the bottom wall 28 a of the oil pan 28. Further, the two left exhaust pipes 40La and 40Lb extend downward along the left front surface of the engine 22, and then extend toward the vehicle rear side through the left side of the side wall 28l of the oil pan 28. . The two exhaust pipes 40La and 40Lb do not extend to the vehicle rear side at the same height below the side portion of the oil pan 28, but the left outer exhaust pipe 40La is obliquely above the inner exhaust pipe 40Lb It is placed out of alignment. The two right exhaust pipes 40Ra and 40Rb extend downward along the front surface of the engine 22 to the right, and then extend to the vehicle rear side through the right side of the side wall 28r of the oil pan 28. The right outer exhaust pipe 40Ra is disposed obliquely upward of the inner exhaust pipe 40Rb. Therefore, the two left exhaust pipes 40La and 40Lb and the two right exhaust pipes 40Ra and 40Rb are disposed along the inclined left and right side walls 28l and 28r of the oil pan 28, respectively. For this reason, the motorcycle 1 of the present embodiment can easily maintain the distance between the exhaust pipes 40La, 40Lb, 40Ra, 40Rb and the road surface during turning of the vehicle, which is advantageous in securing the bank angle.

The front area of the left joint pipe 41L is disposed on the left side of the side wall 28l of the oil pan 28, and the front area of the right joint pipe 41R is disposed on the right of the side wall 28r of the oil pan 28. There is. In addition, rear regions of the left and right combined

pipes

41L and 41R and the muffling chamber 37 are disposed behind the oil pan 28. An upstream oxygen sensor 46 for detecting the oxygen concentration of the exhaust gas before passing through the catalyst 42 is attached to each front region of the left and right merging

pipes

41L and 41R. The upstream oxygen sensor 46 is connected to a controller (not shown) for engine control. The controller receives the detection signal of the upstream oxygen sensor 46 and controls the engine 22 so that the air-fuel ratio of the engine becomes appropriate.

The upstream side oxygen sensor 46 penetrates the peripheral wall of the merging

pipes

41L, 41R and is attached to the merging

pipes

41L, 41R. In the upstream side oxygen sensor 46 attached to the left joining pipe 41L, the wiring connection portion of the main body protrudes toward the upper left of the joining pipe 41L. In the upstream side oxygen sensor 46 attached to the right joining pipe 41R, the wiring connection portion of the main body protrudes toward the upper right of the joining pipe 41R. The upstream side oxygen sensors 46 connected to the left and right merging

pipes

41L and 41R are disposed at respective side positions of the left and right side walls 28l and 28r of the oil pan 28.

FIG. 7 is a view of the muffling chamber 37 of the exhaust device 39 as viewed from the rear upper side, and FIG. 8 is a view of the muffling chamber 37 as viewed from the left side. FIG. 9 is a cross-sectional view of the portion of the muffling chamber 37 taken along the line IX-IX of FIG.
On the upper surface of the muffling chamber 37, two recesses 47 having a substantially rectangular shape in top view are formed. The recess 47 is formed at a substantially central position (in the extending direction of the exhaust

gas introduction pipes

43L, 43R) in the front-rear direction of the left side edge and the right side edge of the upper surface of the muffling chamber 37. The recess 47 has a bottom wall 47a having a square top view and three side walls 47b surrounding three sides around the bottom wall 47a. The side wall 47b is disposed on the front and rear of the bottom wall 47a and on the central side in the width direction of the muffling chamber 37, and the upper side and the outer side (one side) in the width direction are released. Further, the bottom wall 47a of each of the left and right recessed portions 47 is not substantially horizontally formed over the entire area, but is inclined downward toward the outer side (one side) in the width direction. The bottom wall 47 a of each recess 47 is inclined downward to a position where the end of the widthwise outer side (one side) of the muffling chamber 37 is reached.

On the bottom wall 47a of each of the left and right recesses 47, a downstream oxygen sensor 48 is attached that detects the oxygen concentration of the exhaust gas after passing through the catalyst 42. The left and right downstream side oxygen sensors 48 pass through the bottom wall 47a of the corresponding left and right recesses 47 and the

exhaust introducing pipes

43L and 43R (downstream pipe portion 43a), and the oxygen detection portions 48a on the tip side correspond to the left and right. It faces the inside of the exhaust

gas introduction pipes

43L, 43R (downstream pipe portion 43a). In the case of the present embodiment, since the catalyst 42 is disposed in the left and right merging

pipes

41L and 41R, the left and right downstream oxygen sensors 48 are configured to receive the exhaust gas immediately after passing through the catalyst 42 as the exhaust introducing pipe 43L, It can be detected inside 43R. The downstream oxygen sensor 48 outputs a detection signal to a controller for engine control. The controller receives the detection signal of the downstream side oxygen sensor 48 to determine the state of the catalyst 42 and the like. Further, as shown in FIG. 9, each downstream side oxygen sensor 48 is fixed to the corresponding bottom wall 47a and the peripheral wall of the

exhaust introduction pipes

43L, 43R by welding or the like.

In the downstream side oxygen sensor 48 attached to the bottom wall 47a of the corresponding recess 47 on the left and right, the main body 48b exposed to the outside of the muffling chamber 37 slightly protrudes outward in the width direction and protrudes upward. The main body portion 48 b is surrounded by the side wall 47 b of the recess 47 around a range of one third or more in the height direction.

Here, the muffling chamber 37 is formed in a substantially flat cross-sectional shape in which the cross section in the width direction (the cross section orthogonal to the extending direction of the exhaust

gas introduction pipes

43L, 43R) is horizontally long. The left and right recesses 47 are formed symmetrically with respect to the widthwise center C of the muffling chamber 37 in FIG. 7. Further, the left and right

exhaust introduction pipes

43L, 43R and the downstream side oxygen sensor 48 are disposed symmetrically with respect to the widthwise center C of the muffling chamber 37.

Further, as shown in FIGS. 2 and 4, the two merging

pipes

41L and 41R of the exhaust passage 36 are connected to the front wall of the muffling chamber 37 with the rear side inclined inward in the vehicle width direction. That is, the two

joint pipes

41L and 41R are connected to the muffling chamber 37 by inclining so that the overhanging width in the vehicle width direction is gradually narrowed.

Further, as shown in FIG. 6, the muffling chamber 37 is disposed at the rear side position of the oil pan 28 so that most of the upper region is higher than the lower end of the oil pan 28. The downstream side oxygen sensors 48 disposed in the left and right recessed portions 47 of the muffling chamber 37 are disposed at the rear side position of the oil pan 28 and at the inside position in the vehicle width direction overlapping the oil pan 28 in the front-rear direction.

FIG. 10 is a view of the mounting portion of the side stand 60 and a part of the exhaust device 39 as viewed from the left side of the vehicle.
The side stand 60 is attached to a rear area of the down frame 18 on the left side of the vehicle body frame F and a cross pipe (not shown) via a support bracket 61. The side stand 60 is pivotally displaceable between an upright position and a flip-up position about a pivot shaft 62 provided on the support bracket 61.

In the standing position, the side stand 60 stands up in a state where the stand frame 63 contacts the ground portion 63a at the lower end on the road. At this time, the vehicle is kept upright by the stand frame 63 while being slightly inclined to the left. Further, at the flip-up position, the lower end of the stand frame 63 is flipped up to the rear side of the vehicle body with the pivot shaft 62 as the center. As a result, the vehicle does not touch the stand frame 63, and the driver can travel.

In the case of the exhaust system 39 of the present embodiment, the left downstream oxygen sensor 48 attached to the muffling chamber 37 is covered at least in part at the outer side in the vehicle width direction by the stand frame 63 of the side stand 60 in the flipped up position. Is located in Therefore, when the side stand 60 is in the flip-up position, the outside in the vehicle width direction of the left downstream oxygen sensor 48 is protected by the stand frame 63.

Note that, as shown in FIG. 10, a support stay 65 is provided in the muffling chamber 37 so as to project obliquely upward at the front. The end of the stay 65 is fixed to a bracket 66 provided at the lower end of the center frame 16 by a bolt 67. The brackets 66 are provided on the left and right center frames 16 respectively, and the bolts 67 are attached across the left and right brackets 66. Therefore, the muffling chamber 37 is supported by the lower ends of the left and right center frames 16 via the stays 65.

As described above, in the exhaust device 39 of the present embodiment, the oxygen detection portions 48a of the downstream oxygen sensors 48 attached to the muffling chamber 37 are located downstream of the catalyst 42 in the

exhaust introduction pipes

43L and 43R. It is arranged to face. Therefore, the oxygen concentration of the exhaust gas immediately after passing through the catalyst 42 in each of the merging

pipes

41L and 41R can be accurately detected by the downstream side oxygen sensor 48.

In the exhaust device 39 of the present embodiment, the respective downstream oxygen sensors 48 are attached to the recess 47 by penetrating the bottom wall 47 a of the recess 47 of the muffling chamber 37 and the

exhaust introducing pipes

43L, 43R. Therefore, the downstream oxygen sensor 48 can be stably installed without adding a separate mounting part such as a bracket. Therefore, when the configuration of the present embodiment is adopted, the downstream side oxygen sensor 48 can be provided in the

exhaust introduction pipes

43L and 43R and can be stably installed while reducing the product cost.

In the case of the exhaust system 39 of the present embodiment, the bottom wall 47a of each recess 47 provided in the muffling chamber 37 is an end on one side downward toward the opened one side (outside in the vehicle width direction) It is tilted up. Therefore, foreign matter such as water droplets flowing into the respective recesses 47 on the muffling chamber 37 can be discharged to the outside of the recesses 47 quickly along the inclination of the bottom wall 47 a of the recesses 47. For this reason, it is possible to prevent foreign matter such as water droplets from staying in the recess 47 on the muffling chamber 37.

Furthermore, in the exhaust device 39 of the present embodiment, the downstream oxygen sensor 48 is attached to the bottom wall 47a of the recess 47 on the muffling chamber 37, so the entire upper wall of the muffling chamber 37 is lowered to obtain downstream oxygen. Unlike in the case where the mounting portion of the sensor 48 is brought close to the exhaust

gas introducing pipes

43L and 43R, the internal volume of the muffling chamber 37 can be sufficiently secured in portions other than the concave portion 47 of the muffling chamber 37. Therefore, when the configuration of the present embodiment is adopted, noise due to exhaust gas can be advantageously reduced.

Further, in the exhaust device 39 of the present embodiment, since the recess 47 whose three sides are surrounded by the side wall 47 b is formed in the muffling chamber 37, when the muffling chamber 37 is thermally expanded, the three side walls 47 b of the recess 47 are vertically By expanding and contracting, it is possible to suppress the thermal expansion of the muffling chamber 37 in the front-rear direction (the direction along the extending direction of the exhaust

gas introducing pipes

43L, 43R). Therefore, when this embodiment is adopted, it can be suppressed that a large stress acts on the connection portion of the muffling chamber 37 and the joining

pipes

41L, 41R.

Further, in the exhaust system 39 of the present embodiment, a cross section in the vehicle width direction of the muffling chamber 37 (a cross section substantially orthogonal to the extending direction of the

exhaust introduction pipes

43L, 43R) is formed into a horizontally long substantially flat cross sectional shape Two

exhaust inlet pipes

43L and 43R, two recesses 47 and two downstream oxygen sensors 48 are disposed symmetrically in the right and left direction in the muffling chamber 37, respectively. In the case of this embodiment, since the muffling chamber 37 is formed in a horizontally long, substantially flat cross-sectional shape, the occupied height in the vertical direction of the muffling chamber 37 can be suppressed low while securing the internal volume for muffling. . Further, in the exhaust system 39 of the present embodiment, since the shape of the muffling chamber 37 and the arrangement of the

exhaust introducing pipes

43L and 43R and the downstream oxygen sensor 48 are symmetrical, the rigidity maintenance of the muffling chamber 37 and the abnormal noise countermeasure are taken. It can be done advantageously. Furthermore, when the configuration of the present embodiment is adopted, the deformation behavior of the muffling chamber 37 at the time of thermal expansion also becomes the same on both sides and is stable.

Furthermore, in the exhaust system 39 of the present embodiment, the upstream oxygen sensor 46 is attached to each of the merging

pipes

41L and 41R of the exhaust passage 36, and the two upstream oxygen sensors 46 are arranged on the left and right sides of the oil pan 28, respectively. The noise reduction chamber 37 is disposed at the rear of the oil pan 28 and the two downstream oxygen sensors 48 are disposed at an inner position in the vehicle width direction overlapping the oil pan 28 in the front-rear direction. In this case, since the upstream oxygen sensor 46 protruding largely upward from the merging

pipes

41L and 41R is disposed on the left and right sides of the oil pan 28, interference between the upper portion of the upstream oxygen sensor 46 and the oil pan 28 is caused. Accordingly, the height above the ground of the left and right combined

pipes

41L and 41R can be increased.

Further, in the case of the exhaust device 39 of the present embodiment, the muffling chamber 37 is disposed behind the oil pan 28, and the two downstream oxygen sensors 48 are disposed at an inner position in the vehicle width direction overlapping the oil pan in the front and rear direction. Therefore, the left and right combined

pipes

41L and 41R can be moved to the inner side in the vehicle width direction and connected to the muffling chamber 37. Therefore, when the configuration of the present embodiment is adopted, it is possible to narrow the protruding width in the left-right direction of the connection portion of the muffling chamber 37 and the left and right joining

pipes

41L and 41R while increasing the height of the muffling chamber 37 above the ground. it can. Therefore, it is advantageous in securing the bank angle of the vehicle.

In particular, in the case of the exhaust system 39 of the present embodiment, the muffling chamber 37 is located on the rear side of the oil pan 28 and the upper portion (upper side area of the axial center of the exhaust

gas introduction pipes

43L and 43R) It is disposed at a position higher than the lower end of the engine 22 (oil pan 28). Therefore, it is possible to prevent the stepping stones and the like from hitting the muffling chamber 37 and the downstream side oxygen sensor 48 by the engine 22 (oil pan 28) when the vehicle is traveling.

Furthermore, in the exhaust device 39 of the present embodiment, the downstream pipe portion 43a (portion into which the exhaust gas flows into the muffling chamber 37) of the

exhaust introduction pipes

43L, 43R is above the merging

pipes

41L, 41R in which the catalyst 42 is disposed. Because of the offset on the side, the bottom wall 37 b of the muffling chamber 37 can be above the bottom surface of the catalyst 42 by the offset. In addition to the fact that the bottom wall 37b of the muffling chamber 37 can be made higher than the bottom surface of the catalyst 42 as described above, the bottom wall 37b of the muffling chamber 37 is directed toward the rear of the vehicle body. Since the vehicle is inclined upward, the space between the rear area of the bottom wall 37b of the muffling chamber 37 and the road surface can be easily secured at the rear of the vehicle body where a distance to the road surface is required.

Further, in the exhaust device 39 of the present embodiment, the center o2 of the connection portion of the connection pipe 44 to the muffling chamber 37 is positioned above the central axis o1 of the flow of exhaust gas flowing from the exhaust

gas introduction pipes

43L and 43R into the muffling chamber 37. The connection pipe 44 is connected to the muffling chamber 37 so that For this reason, the connecting pipe 44 that easily vibrates when the vehicle travels is connected to the upper region of the muffling chamber 37, and as a result, the distance between the connecting pipe 44 and the road surface during the turning of the vehicle is easily secured. It becomes possible.
Therefore, when the exhaust system 39 of this embodiment is employed, a large bank angle of the vehicle can be secured.

Further, in the exhaust device 39 of the present embodiment, the concave portion 47 is disposed at a substantially central position in the front-rear direction of the muffling chamber 37 (the extending direction of the

exhaust introduction pipes

43L, 43R). Therefore, it is possible to prevent generation of abnormal noise (squeal) in the muffling chamber 37 while keeping the strength of the muffling chamber 37 well-balanced in the front-rear direction by the left and right recesses 47.

Furthermore, in the exhaust system 39 of the present embodiment, the downstream oxygen sensor 48 is surrounded by the side wall 47b of the muffling chamber 37 in the range of 1/3 or more in the height direction. The side walls 47b of 47 can be advantageously protected from the outside.

Further, in the case of the exhaust system 39 of the present embodiment, the downstream oxygen sensor 48 attached to the recess 47 on the left side of the muffling chamber 37 is covered at least in part at the outer side in the vehicle width direction It is placed in position. Therefore, when the configuration of the present embodiment is adopted, the left downstream oxygen sensor 48 can be protected from the outside by the side stand (60) when the vehicle is traveling or the like.

The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the invention.

In addition, the saddle-ride type vehicle according to the present invention is not limited to motorcycles (including motor bikes and scooter type vehicles), but also three wheels (including front two wheels and rear two wheels as well as one front and rear two wheels) Or four-wheeled small vehicles are also included.

1 Motorcycles (saddle type vehicles)
Reference Signs List 22 engine 28 oil pan 35 exhaust port 36 exhaust passage 37 muffling chamber 37b bottom wall 38 main muffler 39 exhaust system 40La, 40Lb, 40Ra,

40Rb exhaust pipe

41L, 41R combined pipe 42

catalyst

43L, 43R exhaust introduction pipe 44 connecting pipe 46 upstream Side oxygen sensor 47 Recess

47a Bottom wall

47b Side wall 48 Downstream oxygen sensor 48a Oxygen detector F Body frame o1 Center axis of exhaust gas flow o2 Center of connection o2 Center of exhaust gas flow passing catalyst

Claims

A catalyst (42) for purifying exhaust gas discharged from the engine (22);
A muffling chamber (37) for muffling exhaust noise of the engine (22) downstream of the catalyst (42);
An exhaust introduction pipe (43L, 43R) having one end connected to an exhaust passage (36) connected to the exhaust port (35) of the engine (22) and the other end projecting into the muffling chamber (37);
A downstream oxygen sensor (48) for detecting the oxygen concentration of the exhaust gas having passed through the catalyst (42);
In the exhaust system of a saddle-ride type vehicle provided with
The muffling chamber (37) has a recess (47) which is surrounded on three sides around the bottom wall (47a) by a side wall (47b) and is open at one side and the upper side.
The bottom wall (47a) of the recess (47) is inclined downward toward the one side to the one end of the one side,
The downstream oxygen sensor (48) is attached to the recess (47) by penetrating the bottom wall (47a) of the recess (47) and the exhaust introduction pipe (43L, 43R);
The oxygen detection portion (48a) of the downstream oxygen sensor (48) is disposed to face the downstream position of the catalyst (42) in the exhaust introduction pipe (43L, 43R). Exhaust system for riding type vehicles.
The muffling chamber (37) is formed in a substantially flat cross-sectional shape in which the cross section substantially orthogonal to the extending direction of the exhaust gas introducing pipe (43L, 43R) is horizontally long.
The exhaust gas inlet pipe (43L, 43R), the recess (47), and the downstream oxygen sensor (48) are arranged two by two in a symmetrical manner in the muffling chamber (37). An exhaust system for a saddle-ride type vehicle according to claim 1.
Connecting pipes (41L, 41R) formed by connecting a plurality of exhaust pipes (40La, 40Lb, 40Ra, 40Rb) are respectively connected to the two exhaust introducing pipes (43L, 43R),
An upstream oxygen sensor (46) for detecting the oxygen concentration of the exhaust gas before passing through the catalyst (42) is attached to each of the merging pipes (41L, 41R),
Two of the upstream oxygen sensors (46) are disposed at each of the left and right side positions of the oil pan (28) of the engine (22),
The muffling chamber (37) is disposed behind the oil pan (28),
The exhaust system of a saddle-ride type vehicle according to claim 2, wherein the two downstream oxygen sensors (48) are disposed at an inner position in the vehicle width direction overlapping the oil pan (28).
The exhaust introduction pipe (43L, 43R) extends from the vehicle front side toward the vehicle rear side, and the center of the flow of exhaust gas flowing from the exhaust introduction pipe (43L, 43R) into the muffling chamber (37) Provided in the sound deadening chamber (37) such that the axis (o1) is located above the central axis (o3) of the flow of exhaust gas passing through the catalyst (42);
The exhaust system of a saddle-ride type vehicle according to any one of claims 1 to 3, wherein a bottom wall (37b) of the muffling chamber (37) is inclined upward toward the rear of the vehicle body. .
Connected to the muffling chamber (37) is a connecting pipe (44) for leading the exhaust gas, which has flowed into the muffling chamber (37) from the exhaust introduction pipe (43L, 43R), to the main muffler (38).
The connection pipe (44) has a central axis (o2) of the flow of exhaust gas, the center (o2) of the connection to the muffling chamber (37) flowing from the exhaust gas introduction pipe (43L, 43R) into the muffling chamber (37). The exhaust system for a saddle-ride type vehicle according to any one of claims 1 to 4, wherein the exhaust system is connected to the muffling chamber (37) so as to be located above the o1).
The said recessed part (47) is arrange | positioned in the approximate center position of the extension direction of the said exhaust gas introduction pipe (43L, 43R) among the said muffling chambers (37). An exhaust system for a saddle-ride type vehicle according to any one of the preceding claims.
The downstream oxygen sensor (48) is characterized in that a range of one third or more in the height direction is surrounded by the side wall (47b) of the muffling chamber (37). An exhaust system for a saddle-ride type vehicle according to any one of the preceding claims.
On the vehicle body frame (F), the side stand (60) of the vehicle is attached so as to be pivotable
The downstream oxygen sensor (48) is disposed at a position where at least a part of the downstream side in the vehicle width direction is covered by the side stand (60) in the flip-up position. An exhaust system for a saddle-ride type vehicle according to any one of the preceding claims.