JP7095437B2 - Motorcycle exhaust system - Google Patents

Description

The present invention relates to an exhaust device for a motorcycle.

Usually, a motorcycle is equipped with an exhaust device having a muffler or the like in order to mute the exhaust noise generated when the exhaust from the internal combustion engine is discharged to the outside. On the other hand, since the back pressure is increased by providing the exhaust device, the output performance at high speed running may be suppressed. In order to improve the output performance at high speeds, it is conceivable to increase the passage area of the exhaust passage in the exhaust device or shorten the length of the exhaust passage, but conversely, the output performance deteriorates at low speeds. It will pass.

Japanese Patent No. 4749982

To solve such a problem, Patent Document 1 discloses a motorcycle having an exhaust valve in the exhaust device. In a motorcycle equipped with an exhaust valve, the output performance is improved by adjusting the exhaust passage area between high-speed driving and low-speed driving.
On the other hand, when traveling at low speeds, high muffling performance is desired because the vehicle is often traveling in a place where the influence of noise is large, such as an urban area or a residential area. In order to improve the muffling performance at low speeds, the exhaust valve may be closed, but if it is closed too much, the back pressure becomes too high, which is a contradictory problem. Although it may be possible to solve the problem by increasing the size of the muffler, there is a risk that the appearance, weight, bank angle, etc. of the vehicle will be adversely affected.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to improve the muffling performance at low speeds.

The exhaust device for a motorcycle according to the present invention includes a plurality of exhaust pipes connected to an exhaust port of an internal combustion engine, a collective pipe for collecting the plurality of exhaust pipes, and a joint pipe for connecting the collective pipe and the muffler. An exhaust device for a motorcycle provided with an exhaust control valve attached to the joint pipe to change the passage area of the exhaust passage, and a bypass pipe for communicating the exhaust passages on the upstream side and the downstream side of the exhaust control valve. The joint pipe is provided with a partition portion that divides the exhaust passage into a main passage and a sub passage, and is fixed in a state of being inserted into the connector member of the muffler. The bypass pipe has a downstream end of the joint. It is connected to the pipe and is connected to the sub-passage via a curved portion, and the partition wall portion has a first partition wall provided on the joint pipe and a second partition wall provided on the muffler. It is characterized by being .

According to the present invention, it is possible to improve the muffling performance at low speed traveling.

It is a right side view which shows an example of the structure of a motorcycle. It is a bottom view which shows an example of the structure of a motorcycle. It is a left side view which shows an example of the structure of an exhaust device. It is sectional drawing which shows an example of the structure of an exhaust device. It is a cross-sectional perspective view which enlarged a part of an exhaust device.

In the embodiment of the present invention, the plurality of exhaust pipes 21a to 21d connected to the exhaust port of the internal combustion engine, the collective pipe 23 for collecting the plurality of exhaust pipes 21a to 21d, and the collective pipe 23 and the muffler 35 are connected. The exhaust device 20 of the motorcycle 1 including the joint pipe 26 and the exhaust control valve 28 attached to the joint pipe 26 to change the passage area of the exhaust passage, on the upstream side and the downstream side of the exhaust control valve 28. The bypass pipe 55 has a bypass pipe 55 that communicates with the exhaust passage, and the downstream end of the bypass pipe 55 is connected to the joint pipe 26. Therefore, when the vehicle travels at a low speed, the exhaust control valve 28 can be closed more than before by exhausting the air through the bypass pipe 55. Therefore, the exhaust control valve 28 can shut off the exhaust noise and improve the muffling performance. Further, by closing the exhaust control valve 28 more than before, the exhaust gas mainly passes through the bypass pipe 55, so that the length of the exhaust passage can be lengthened and the muffling performance can be improved.

(Example)
Hereinafter, a preferred embodiment of the exhaust device for a motorcycle according to the present embodiment will be described with reference to the accompanying drawings.
FIG. 1 is a right side view showing an example of the configuration of the motorcycle 1. If necessary, the front side of the vehicle is indicated by the arrow "front" and the opposite is referred to as the rear side in the drawing. The left side of the vehicle is indicated by the arrow "left", and the opposite is the right side. In addition, the upper side of the vehicle is indicated by the arrow "upper", and the opposite is the lower side.

The motorcycle 1 has a body frame formed of a body frame 100 made of steel or an aluminum alloy. The body frame 100 supports components or parts such as the engine 10. A pair of front forks 103 that can be rotated left and right are supported on the front portion of the vehicle body frame 100 by a steering head pipe 102. A handlebar is fixed to the upper end of the front fork 103 via a steering bracket. A front wheel 104 is rotatably supported under the front fork 103. A front fender is attached to the upper side of the front wheel 104.

The vehicle body frame 100 is configured as a so-called twin spar type frame having a main frame portion 101a and a pivot frame portion 101b. The main frame portion 101a is integrally connected to the rear portion of the steering head pipe 102, and is bifurcated in pairs on the left and right toward the rear side. The pivot frame portion 101b extends from the main frame portion 101a toward the rear lower side. The vehicle body frame 100 has a three-dimensional structure having a space inside by the main frame portion 101a and the pivot frame portion 101b. The engine 10 as an internal combustion engine is mounted inside the vehicle body frame 100.

In the pivot frame portion 101b, the swing arm 106 is supported so as to be swingable in the vertical direction via the pivot shaft 105 at substantially the center in the vertical direction. A rear wheel 107 is rotatably supported at the rear end of the swing arm 106. A rear fender is attached to the front upper side of the rear wheel 107. The power of the engine 10 is transmitted to the rear wheels 107 via the power transmission chain, so that the rear wheels 107 rotate and the motorcycle 1 travels. A rear shock absorber 108 is mounted between the vehicle body frame 100 and the swing arm 106 via a link mechanism.
The seat rail 109 extends from the vicinity of the rear portion of the main frame portion 101a toward the upper side of the rear wheel 107 with an appropriate inclination toward the rear upper side. The seat rail 109 supports the seating seat. A fuel tank covered by a tank cover is mounted on the front side of the seat.

As the engine 10, for example, a water-cooled multi-cylinder 4-cycle gasoline engine is used. In this embodiment, a parallel 4-cylinder engine in which four cylinders are arranged side by side in the left-right direction (vehicle width direction) will be described, but the present invention is not limited to this case.
The engine 10 is configured by integrally coupling the crankcase 12, the cylinder block 13, the cylinder head 14, and the cylinder head cover 15 so as to sequentially overlap with each other so as to accommodate and support the crankshaft 11 along the left-right direction. Cylinder. An oil pan 16 is attached to the lower part of the crankcase 12. The engine 10 is supported by the vehicle body frame 100 in a state where the cylinder axis is appropriately inclined to the front side. The engine 10 is integrally coupled and supported inside the vehicle body frame 100 by being suspended via a plurality of engine mounts, and the engine 10 itself acts as a rigid member of the vehicle body frame 100.

A transmission case 17 is integrally formed at the rear of the crankcase 12. A counter shaft and a plurality of transmission gears are arranged inside the transmission case 17. The power of the engine 10 passes through the transmission from the crankshaft 11 and finally rotates the rear wheel 107 via the power transmission chain. The crankcase 12 and the transmission case 17 are integrally coupled to each other to form a casing assembly of the engine unit including the engine 10 as a whole. A plurality of auxiliary equipment such as a starter motor for starting an engine, a clutch device, etc. are coupled to appropriate positions in the casing assembly.

Further, the motorcycle 1 has an intake device for supplying an air-fuel mixture composed of an intake air supplied from an air cleaner and a fuel supplied from a fuel supply device, an exhaust device for discharging exhaust gas after combustion from the engine 10, and the like.
First, the intake device will be described.
The intake device includes an air cleaner, an intake pipe, a throttle body, and the like. Intake ports corresponding to a plurality of (here, four) cylinders are formed on the rear side of the cylinder head 14 of the engine 10, and a throttle body is connected to each intake port via an intake pipe. The throttle body has a throttle valve that opens and closes the intake passage according to the accelerator opening, and controls the amount of intake air supplied from the air cleaner. An injector for fuel injection is arranged on the downstream side of the throttle body. The injector injects fuel into the intake flow path in the throttle body at a predetermined timing to supply an air-fuel mixture to each cylinder of the cylinder head 14.

Next, the exhaust device 20 will be described with reference to FIGS. 1 to 5.
FIG. 2 is a bottom view showing an example of the configuration of the motorcycle 1.
The exhaust device 20 includes a first exhaust pipe 21a to a fourth exhaust pipe 21d, a first merging pipe 22a, a second merging pipe 22b, a collecting pipe 23, a catalyst case 24, a joint pipe 26, a muffler 35, and the like. .. The first exhaust pipe 21a to the fourth exhaust pipe 21d, the first merging pipe 22a, the second merging pipe 22b, the collecting pipe 23, the catalyst case 24, and the joint pipe 26 are integrally formed by welding, for example.

Exhaust ports corresponding to a plurality of (here, four) cylinders are formed on the front side of the cylinder head 14 of the engine 10, and the first exhaust pipes 21a to the fourth exhaust pipes 21d are connected to each exhaust port. Here, the first exhaust pipe 21a is the first from the left, the second exhaust pipe 21b is the second from the left, the third exhaust pipe 21c is the third from the left, and the fourth exhaust pipe 21d is the left. It is located at the 4th position from each. The first exhaust pipe 21a to the fourth exhaust pipe 21d extend downward from the exhaust port through the front side of the cylinder block 13 and the front side of the crankcase 12, respectively, and extend toward the rear side after being curved. Issue (see Figure 1).

The first exhaust pipe 21a and the second exhaust pipe 21b are connected to the first merging pipe 22a, and the third exhaust pipe 21c and the fourth exhaust pipe 21d are connected to the second merging pipe 22b (FIG. See 2). Each exhaust pipe and the merging pipe are connected by welding, for example. The first merging pipe 22a and the second merging pipe 22b are arranged side by side in parallel on the left and right sides, respectively. Further, the first merging pipe 22a and the second merging pipe 22b are located below the crankcase 12. The oil pan 16 attached to the crankcase 12 is located on the right side (one side) of the lower portion of the crankcase 12 in the vehicle width direction. Therefore, the first merging pipe 22a and the second merging pipe 22b are arranged unevenly on the left side (the other side) in the vehicle width direction from the vehicle center line C so as not to interfere with the oil pan 16.

The first merging pipe 22a and the second merging pipe 22b are connected to the collecting pipe 23. The first merging pipe 22a and the second merging pipe 22b and the collecting pipe 23 are connected by, for example, welding. The collecting pipe 23 is located below the crankcase 12. Similar to the first merging pipe 22a and the second merging pipe 22b, the collecting pipe 23 is also arranged unevenly from the vehicle center line C to the other side (here, the left side) in the vehicle width direction so as not to interfere with the oil pan 16. Will be done.

The collecting pipe 23 is connected to the catalyst case 24. The collecting pipe 23 and the catalyst case 24 are connected by welding, for example. The catalyst case 24 has a substantially pipe shape, and a catalyst converter for purifying harmful components of exhaust gas is arranged inside. The catalyst case 24 is located below the pivot frame portion 101b and is fixed to the pivot frame portion 101b via the bracket 25. As shown in FIG. 2, the collecting pipe 23 and the catalyst case 24 extend so that the axis line is inclined from the left side to the right side from the front side to the rear side.

The catalyst case 24 is connected to the joint pipe 26. The catalyst case 24 and the joint pipe 26 are connected by welding, for example. The joint pipe 26 connects the collecting pipe 23 and the muffler 35 via the catalyst case 24. As shown in FIG. 1, the joint pipe 26 extends so as to incline to the rear upper side from the front side to the rear side. Further, the joint pipe 26 is arranged so that a part thereof overlaps with the link mechanism. Further, as shown in FIG. 2, the joint pipe 26 extends so that the axis line is inclined from the left side to the right side from the front side to the rear side.

The joint pipe 26 of this embodiment is composed of a first joint pipe member 27a and a second joint pipe member 27b. The first joint pipe member 27a and the second joint pipe member 27b are connected to each other by welding, for example, to function as one joint pipe 26.
Here, the exhaust control valve 28 is attached to the inside of the first joint pipe member 27a. The exhaust control valve 28 can change the passage area of the exhaust passage in the joint pipe 26 by adjusting the opening / closing angle. That is, the exhaust control valve 28 controls the amount of exhaust gas flowing through the first joint pipe member 27a.

FIG. 3 is a left side view showing an example of the configuration of the exhaust device 20. FIG. 4 is a cross-sectional view showing an example of the configuration of the exhaust device 20. FIG. 5 is an enlarged cross-sectional perspective view of a part of the exhaust device 20.
As shown in FIG. 3, the exhaust control valve 28 rotates about a rotation shaft 29 orthogonal to the extension direction of the first joint pipe member 27a. The rotation of the exhaust control valve 28 in the opening direction increases the passage area of the exhaust passage, and the rotation of the exhaust control valve 28 in the closing direction reduces the passage area of the exhaust passage. The exhaust control valve 28 is connected to the actuator via a wire or cable on the outside of the first joint pipe member 27a. The ECU provided in the motorcycle 1 acquires information such as the engine speed, and controls the actuator based on the acquired information to rotate the exhaust control valve 28.

The joint pipe 26 is connected to the muffler 35 via a connector member 39 described later. The muffler 35 extends so as to incline to the rear upper side from the front side to the rear side. Further, the muffler 35 is fixed to the seat rail 109 via a mounting bracket 52 coupled to the upper part of the main body 45. As shown in FIG. 4, the muffler 35 has a cone portion 36, a main body portion 45, a baffle pipe 60, and the like.

The cone portion 36 has a double structure and has an outer cone member 37a and an inner cone member 37b. The outer diameters of the outer cone member 37a and the inner cone member 37b are gradually increased from the front side to the rear side, respectively. A linear and substantially cylindrical connecting portion 38 is formed on the front end side of the outer cone member 37a (see also FIG. 5). The connector member 39 is connected to the connecting portion 38. The connector member 39 is connected to the rear end of the joint pipe 26 to connect the joint pipe 26 and the muffler 35. Since the inner diameter of the connector member 39 is larger than the outer diameter of the joint pipe 26, the joint pipe 26 is connected in a state of being fitted in the connector member 39. In the state where the connector member 39 and the joint pipe 26 are connected, the gasket is interposed between the inner circumference of the connector member 39 and the outer circumference of the joint pipe 26 to prevent the exhaust gas from leaking to the outside. ..

The main body 45 has a double structure and has an outer cylinder member 46a and an inner cylinder member 46b (see FIG. 4). A gap is formed between the outer cylinder member 46a and the inner cylinder member 46b, and various sound absorbing materials such as glass wool are provided in this gap.
The main body 45 is closed by the rear wall 47 and is partitioned by the baffle plate 48 as a partition to form a plurality of expansion chambers. The main body 45 of this embodiment is formed with two chambers, a first expansion chamber 49a located on the front side and a second expansion chamber 49b located on the rear side. In the baffle plate 48, the main body portion 45 is divided into approximately 3: 5 on the front side and the rear side, so that the volume of the first expansion chamber 49a is smaller than the volume of the second expansion chamber 49b.

A communication pipe 50 communicates between the first expansion chamber 49a and the second expansion chamber 49b. The communication pipe 50 is arranged linearly so that the extension direction is parallel to the extension direction of the main body 45. Specifically, the communication pipe 50 is fixed in a state of being inserted into a hole formed slightly above the center of the baffle plate 48. By arranging the communication pipe 50 in this way, the exhaust gas of the first expansion chamber 49a flows through the communication pipe 50 to the second expansion chamber 49b.
Further, the second expansion chamber 49 and the outside are communicated with each other by a tail pipe 51. The tail pipe 51 is arranged linearly so that the extending direction is parallel to the extending direction of the main body 45. Specifically, the tail pipe 51 is fixed in a state of being inserted into a hole formed slightly above the center of the rear wall 47. By arranging the tail pipe 51 in this way, the exhaust gas of the second expansion chamber 49b is discharged to the outside through the tail pipe 51.
The inner diameters of the communication pipe 50 and the tail pipe 51 are substantially the same, and the central axes of the communication pipes 50 and the tail pipe 51 substantially coincide with each other in a straight line. Further, the rear end of the communication pipe 50 and the front end of the tail pipe 51 face each other through a gap in the second expansion chamber 49.

Next, in the exhaust device 20 of the present embodiment, a structure capable of improving the output performance at high speed running and improving the muffling performance at low speed running will be described.
The exhaust device 20 of this embodiment has a bypass pipe 55 for exhaust gas to bypass a part of the exhaust passage in the joint pipe 26. The inside of the bypass pipe 55 functions as an exhaust passage for exhaust gas. The inner diameter (or outer diameter) of the bypass pipe 55 is larger than the inner diameter (or outer diameter) of the joint pipe 26. Therefore, the passage area of the bypass pipe 55 is smaller than the passage area of the joint pipe 26.
As shown in FIG. 3, the bypass pipe 55 is formed in a substantially U shape. The bypass pipe 55 includes an upstream portion 56a, an intermediate portion 56b, and a downstream portion 56c integrally. The upstream portion 56a and the downstream portion 56c are gently curved, and the intermediate portion 56b is formed in a substantially linear shape. Here, the upstream portion 56a and the downstream portion 56c correspond to an example of the curved portion.

As shown in FIGS. 3 and 4, the bypass pipe 55 is coupled to the joint pipe 26. Specifically, the upstream portion 56a of the bypass pipe 55 communicates with the first opening 30 formed in the lower portion of the first joint pipe member 27a and upstream of the exhaust control valve 28. They are joined by welding, for example. The upstream portion 56a is coupled from a direction substantially orthogonal to the extending direction of the first joint pipe member 27a. On the other hand, the downstream portion 56c of the bypass pipe 55 is joined, for example, by welding so as to communicate with the second opening 31 formed in the substantially center and lower portion of the second joint pipe member 27b in the extending direction. The downstream portion 56c is coupled from a direction substantially orthogonal to the extending direction of the second joint pipe member 27b.
By connecting the bypass pipe 55 to the joint pipe 26 in this way, the upstream and downstream exhaust passages of the exhaust control valve 28 among the exhaust passages formed by the joint pipe 26 communicate with each other. Here, since the upstream portion 56a and the downstream portion 56c of the bypass pipe 55 are curved, when compared in the range L shown in FIG. 4 (the range from the first opening 30 to the second opening 31). , The length of the exhaust passage of the bypass pipe 55 is longer than the length of the exhaust passage of the joint pipe 26.

Further, as shown in FIG. 2, the bypass pipe 55 is located below the joint pipe 26, and a part (or all) of the bypass pipe 55 overlaps with the joint pipe 26. Further, the bypass pipe 55 is located inside the vehicle with respect to the outer end (outer outline) of the joint pipe 26. Therefore, it is possible to suppress the influence on the appearance and the bank angle of the exhaust device 20. Further, the bypass pipe 55 can prevent interference with, for example, the legs of an occupant who has touched the ground.
Further, as shown in FIGS. 4 and 5, the second joint pipe member 27b of the joint pipe 26 has a first partition wall 32 that divides the exhaust passage into two passages. Specifically, the first partition wall 32 has a substantially plate shape curved so as to project upward, and extends over the inner peripheral surface on the right side and the inner peripheral surface on the left side of the second joint pipe member 27b. It is combined so that it can be crossed over. Therefore, inside the second joint pipe member 27b, the first main passage 33a is formed on the upper side and the first sub passage 33b is formed on the lower side by being partitioned by the first partition wall 32. The passage area of the first main passage 33a is larger than the passage area of the first sub passage 33b. The passage area of the first sub-passage 33b is larger than the passage area of the bypass pipe 55.
Here, the front end of the first partition wall 32 is located on the downstream side of the exhaust control valve 28. Further, the front end side of the first partition wall 32 covers the second opening 31 of the bypass pipe 55 from the inside and the upper side of the second joint pipe member 27b. Therefore, the exhaust passage of the bypass pipe 55 and the first sub-passage 33b of the second joint pipe member 27b communicate with each other. That is, the exhaust gas flowing through the bypass pipe 55 does not flow into the first main passage 33a but flows into the first sub-passage 33b. On the other hand, the rear end of the first partition wall 32 is located at the rear end of the second joint pipe member 27b.

Further, as shown in FIG. 5, a baffle pipe 60 is connected to the connection portion 38 of the outer cone member 37a and the front end of the inner cone member 37b by, for example, welding. The baffle pipe 60 is arranged linearly so that the extending direction is parallel to the extending direction of the muffler 35.
The baffle pipe 60 has a front side portion 61a located on the front side and a rear side portion 61b located on the rear side. The front side portion 61a is joined by welding, for example, in a state of being sandwiched between the connection portion 38 and the connector member 39. Further, in the rear side portion 61b, the front end of the inner cone member 37b is joined to the outer peripheral surface by welding, for example. The rear side portion 61b extends from the front side portion 61a toward the inside of the muffler 35 and reaches the inside of the cone portion 36 and the inside of the main body portion 45 of the muffler 35.
As shown in FIG. 4, the central axes of the rear side portion 61b and the communication pipe 50 substantially coincide with each other in a straight line. Here, the rear end of the rear side portion 61b and the front end of the communication pipe 50 face each other through a gap in the first expansion chamber 49a. The inner diameter of the rear side portion 61b is larger than the inner diameter of the communication pipe 50. Further, the rear side portion 61b has substantially the same inner diameter as the inner diameter of the second joint pipe member 27b, and the respective central axes substantially coincide with each other in a straight line.
An opening 62 is formed in the rear side portion 61b of the baffle pipe 60 at a portion located in the muffler 35, specifically, in the cone portion 36. The opening 62 functions as an exit of the second sub-passage 33b and faces in a direction orthogonal to the extending direction of the baffle pipe 60, in this case toward the lower side of the vehicle, with the first expansion chamber 49a. Communicate.

Further, the baffle pipe 60 has a second partition wall 63 that divides the internal exhaust passage into two passages, similarly to the first partition wall 32 provided on the second joint pipe member 27b. Specifically, the second partition wall 63 has a substantially plate shape curved so as to project upward, and spans the inner peripheral surface on the right side and the inner peripheral surface on the left side of the baffle pipe 60. It is combined so that it can be used. Therefore, by partitioning the inside of the baffle pipe 60 into the second partition wall 63, the second main passage 64a is formed on the upper side and the second sub passage 64b is formed on the lower side. The passage area of the second main passage 64a is larger than the passage area of the second sub passage 64b. The passage area of the second sub-passage 64b is larger than the passage area of the bypass pipe 55.
Here, the rear end side of the second partition wall 63 covers the opening 62 from the inside and the upper side of the baffle pipe 60. Therefore, the second sub-passage 64b and the first expansion chamber 49a communicate with each other. On the other hand, the front end of the second partition wall 63 is located at the front end of the rear side portion 61b of the baffle pipe 60.

Here, the second partition wall 63 is curved with substantially the same radius of curvature as the first partition wall 32, and is partitioned in substantially the same manner as the first partition wall 32. Therefore, the first main passage 33a and the second main passage 64a communicate with each other with substantially the same cross-sectional shape. Similarly, the first sub-passage 33b and the second sub-passage 64b communicate with each other in substantially the same cross-sectional shape. Therefore, the exhaust gas from the first main passage 33a flows directly to the second main passage 64a, and the exhaust gas from the first sub-passage 33b flows to the second sub-passage 64b as it is.
The rear end of the first partition wall 32 and the front end of the second partition wall 63 face each other through a gap without contacting each other. However, the gap between the first partition wall 32 and the second partition wall 63 is small, and the gap is located so as not to intersect the flow of exhaust gas. Therefore, it is possible to prevent the exhaust gas from leaking from the first main passage 33a to the second sub-passage 64b or leaking from the first sub-passage 33b to the second main passage 64a through the gap. ..
Here, the first partition wall 32 and the second partition wall 63 correspond to an example of a partition wall portion that divides the exhaust passage into a main passage and a sub passage. In this way, by separating the partition wall portion between the first partition wall 32 on the joint pipe 26 side and the second partition wall 63 on the muffler 35 side, the manufacturability and assemblability are improved as compared with the integral configuration. Can be improved.

Next, a case where the joint pipe 26 and the muffler 35 are connected will be described. First, the joint pipe 26 and the muffler 35, which have been completed as a unit in advance, are prepared. Here, the parts included on the joint pipe 26 side are the first partition wall 32 and the like. A gasket is attached to the outer periphery of the portion of the joint pipe 26 connected to the muffler 35. On the other hand, the parts included on the muffler 35 side are the connector member 39, the baffle pipe 60, the second partition wall 63, and the like.
The operator inserts the rear end of the joint pipe 26 into the connector member 39 of the muffler 35. At this time, the rear end of the first partition wall 32 of the joint pipe 26 and the front end of the second partition wall 63 of the muffler 35 are aligned so as to face each other with a slight gap. Therefore, the first partition wall 32 and the second partition wall 63 communicate the first main passage 33a of the joint pipe 26 and the first main passage 64a of the baffle pipe 60, and the first sub of the joint pipe 26. The passage 33b and the second sub-passage 64b of the baffle pipe 60 communicate with each other. Finally, the operator fixes the outer periphery of the connector member 39 with the crank member, so that the joint pipe 26 and the muffler 35 are connected.

Next, the flow of the exhaust gas in the high-speed running and the low-speed running of the exhaust device 20 configured as described above will be described.
When traveling at high speed, that is, when the engine speed is within a predetermined high speed range, the actuator rotates in the direction of opening the exhaust control valve 28 in response to an instruction from the ECU to open the exhaust control valve 28. In this case, as shown by the white arrow in FIG. 4, the exhaust gas from the engine 10 mainly flows from the first main passage 33a of the joint pipe 26 to the second main passage 64a of the baffle pipe 60, and then the baffle. The pipe 60 is exhausted straight through the first expansion chamber 49a, the communication pipe 50, the second expansion chamber 49b, and the tail pipe 51. That is, since most of the exhaust gas does not pass through the bypass pipe 55 coupled to the joint pipe 26, the length of the exhaust passage is shortened, and the output performance at high speed traveling can be improved. In particular, since the rear end of the baffle pipe 60 and the front end of the communication pipe 50 are arranged so as to face each other, most of the exhaust gas from the first main passage 64a is directly in the communication pipe 50 from the baffle pipe 60. It flows.

On the other hand, when traveling at a low speed, that is, when the engine speed is within a predetermined low speed range, the actuator rotates the exhaust control valve 28 in the closing direction in response to an instruction from the ECU to close the exhaust control valve 28. In this case, as shown by the black arrow in FIG. 4, the exhaust gas from the engine 10 mainly passes through the bypass pipe 55 from the first sub-passage 33b of the joint pipe 26 to the second sub-passage 64b of the baffle pipe 60. Is subsequently exhausted through the first expansion chamber 49a, the communication pipe 50, the second expansion chamber 49b, and the tail pipe 51. That is, since most of the exhaust gas passes through the bypass pipe 55, the length of the exhaust passage becomes longer by the amount that the bypass pipe 55 is curved, and the muffling performance at low speed traveling can be improved. In particular, the opening 62 of the second sub-passage 64b does not face the front end of the communication pipe 50 and points toward the lower side of the vehicle. The first expansion chamber 49a is located on the side facing the opening 62, and most of the exhaust gas from the bypass pipe 55 passes through the first expansion chamber 49a from the baffle pipe 60, so that the first expansion chamber 49a Can be effectively used to mute the sound. Further, by having the bypass pipe 55, the exhaust control valve 28 can be closed more than before when traveling at a low speed, so that the muffling performance can be further improved.

As described above, according to the exhaust device 20 of the present embodiment, the bypass pipe 55 has a bypass pipe 55 that communicates the exhaust passages on the upstream side and the downstream side of the exhaust control valve 28, and the bypass pipe 55 is the end portion of the downstream portion 56c. The downstream end) is connected to the joint pipe 26.
Therefore, when the vehicle travels at a low speed, the exhaust control valve 28 can be closed more than before by exhausting the air through the bypass pipe 55. Therefore, the exhaust control valve 28 can shut off the exhaust noise and improve the muffling performance. Further, by closing the exhaust control valve 28 more than before, the exhaust gas mainly passes through the bypass pipe 55, so that the length of the exhaust passage can be lengthened and the muffling performance can be improved. Further, since it is not necessary to increase the size of the muffler 35, it is possible to eliminate adverse effects such as the appearance and weight of the vehicle and the bank angle.

Further, since the bypass pipe 55 is connected to the joint pipe 26 without being connected to the muffler 35, the joint pipe 26 and the muffler 35 can be easily connected, and the manufacturability can be improved and the sealing property can be improved. be able to. If both the joint pipe 26 and the bypass pipe 55 are connected to the muffler 35, it is not easy to manufacture, the sealing property is deteriorated, and there is a risk of exhaust leakage.

Further, according to the exhaust device 20 of the present embodiment, the joint pipe 26 is provided with a first partition wall 32 that divides the exhaust passage into the first main passage 33a and the first sub passage 33b, and the bypass pipe 55 is provided with a first partition pipe. It is connected to the first sub-passage 33b via a downstream portion 56c as a curved portion. Therefore, when traveling at a low speed, the exhaust gas mainly passes through the bypass pipe 55 and passes through the first sub-passage 33b having a small exhaust passage area, so that the muffling performance can be improved. Further, since the bypass pipe 55 has a curved portion, the length of the exhaust passage can be lengthened, and the muffling performance can be improved. Further, by providing the second sub-passage 33b in the joint pipe 26, it is possible to suppress the influence on the appearance and the bank angle of the exhaust device 20.

Further, the second sub-passage 64b of this embodiment is provided up to the inside of the muffler 35. Therefore, the length of the exhaust passage of the second sub-passage 64b can be lengthened, and the muffling performance during low-speed traveling can be improved.
Further, the joint pipe 26 of this embodiment is fixed in a state of being inserted into the connector member 39 of the muffler 35, and has a first partition wall 32 provided on the joint pipe 26 and a second partition wall 63 provided on the muffler 35. Has. Since the joint pipe 26 is fixed in a state of being inserted into the connector member 39 of the muffler 35, the manufacturability and the sealing property can be improved. Further, by making the joint pipe 26 and the muffler 35 separate partition walls, the manufacturability of the exhaust device 20 can be improved.

Further, the opening 62 as an exit of the second sub-passage 64b in the muffler 35 of this embodiment faces the lower side of the vehicle. That is, by not facing the outlet of the second sub-passage 64b with the communication pipe 50, the length of the exhaust passage passing through the second sub-passage 64b can be lengthened, and the muffling performance can be improved.
Further, the bypass pipe 55 of this embodiment is located on the lower side of the joint pipe 26 and inside the vehicle from the outer end of the joint pipe 26. Therefore, even if the bypass pipe 55 is newly provided, the influence on the appearance and the bank angle can be suppressed.

Although the examples according to the present invention have been described above, the present invention is not limited to the above-mentioned examples, and changes can be made within the scope of the present invention.
In the above-described embodiment, the case where the engine 10 is a parallel 4-cylinder engine and the exhaust device 20 has the first exhaust pipe 21a to the fourth exhaust pipe 21d has been described, but the present invention is not limited to this case. That is, it may be a multi-cylinder engine, and the exhaust device 20 may have two or more exhaust pipes. For example, in the case of two exhaust pipes, the above-mentioned merging pipes 22a to 22b can be eliminated and the two exhaust pipes can be directly connected to the collecting pipe 23.

In the above-described embodiment, the case where the collecting pipe 23 is connected to the catalyst case 24 and the catalyst case 24 is connected to the joint pipe 26 has been described, but the present invention is not limited to this case. The catalyst case 24 may be arranged at any position in the exhaust passage in the exhaust device 20.
In the above-described embodiment, the case where the joint pipe 26 is composed of the first joint pipe member 27a and the second joint pipe member 27b has been described, but the case is not limited to this case. The joint pipe 26 may be composed of one pipe member or three or more pipe members.

1: Motorcycle 10: Engine (internal combustion engine) 20: Exhaust device 21a-21d: Exhaust pipe 24: Collective pipe 26: Joint pipe 28: Exhaust control valve 31: Second opening 32: First partition 33a: First 1 main passage 33b: 1st sub passage 35: muffler 39: connector member 55: bypass pipe 62: opening (exhaust) 63: second partition 64a: second main passage 64b: second sub passage

Claims (4)

A plurality of exhaust pipes connected to the exhaust port of the internal combustion engine, a collective pipe for collecting the plurality of exhaust pipes, a joint pipe for connecting the collective pipe and the muffler, and a passage of the exhaust passage attached to the joint pipe. An exhaust device for a motorcycle equipped with an exhaust control valve that changes the area.
It has a bypass pipe that communicates the exhaust passages on the upstream side and the downstream side of the exhaust control valve.
The joint pipe is provided with a partition wall portion that divides the exhaust passage into a main passage and a sub passage, and is fixed in a state of being inserted into the connector member of the muffler.
The bypass pipe has a downstream end connected to the joint pipe and is connected to the sub-passage via a curved portion.
An exhaust device for a motorcycle , wherein the partition wall portion has a first partition wall provided on the joint pipe and a second partition wall provided on the muffler . The exhaust device for a motorcycle according to claim 1 , wherein the sub-passage is provided up to the inside of the muffler. The motorcycle exhaust device according to claim 1 or 2 , wherein the outlet of the sub-passage in the muffler faces the lower side of the vehicle. The automatic according to any one of claims 1 to 3 , wherein the bypass pipe is located below the joint pipe and inside the vehicle with respect to the outer end of the joint pipe. Motorcycle exhaust system.

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