Exhaust device

Abstract

To provide an exhaust device enabling both of output improvement and muffling effects when opening an exhaust valve.SOLUTION: An exhaust device (30) includes: a muffler (34) having an expansion chamber (A); a discharge exhaust pipe (55) for discharging combustion gas (G) from the muffler (34); and an exhaust valve mechanism (40) that regulates a flow rate of the combustion gas (G) by using an opening / closing type exhaust valve (42). The discharge exhaust pipe (55) is coupled to the expansion chamber (A), and the exhaust valve (42) is provided in an upstream side exhaust pipe (50) for introducing the combustion gas (G) to the expansion chamber (A). The exhaust device is configured to introduce the combustion gas (G) to the expansion chamber (A) even while the exhaust valve (42) is closed.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an exhaust system, and more particularly to an exhaust system equipped with an exhaust valve mechanism that adjusts the flow rate of combustion gas with an exhaust valve that opens and closes. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in an exhaust system that purifies and silences combustion gas from an internal combustion engine before discharging it, a configuration that includes an exhaust valve mechanism that adjusts the flow rate of the combustion gas with an exhaust valve such as a butterfly valve has been known.

[0003] Patent Document 1 discloses an exhaust device in which an exhaust valve mechanism is attached to a connecting pipe that is connected to the upstream side of a muffler that has an expansion chamber for combustion gas. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-85954 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the configuration of Patent Document 1, when the exhaust valve is opened, the combustion gas is discharged to the outside of the muffler through a straight pipe without passing through the expansion chamber inside the muffler. This makes it easy to improve output at high speeds, etc., but it also poses the problem of loud exhaust noise.

[0006] An object of the present invention is to provide an exhaust device which overcomes the problems of the conventional technology and which is capable of achieving both improved output and a silencing effect when the exhaust valve is open. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the present invention provides an exhaust system (30) having a muffler (34) provided with an expansion chamber (A), an exhaust pipe (55) for discharging combustion gas (G) from the muffler (34), and an exhaust valve mechanism (40) for adjusting the flow rate of the combustion gas (G) with an open / close exhaust valve (42), wherein the exhaust pipe (55) is connected to the expansion chamber (A), and the exhaust valve (42) is provided in an upstream exhaust pipe (50) that introduces the combustion gas (G) into the expansion chamber (A). A first feature of the present invention is that the exhaust pipe (55) is connected to the expansion chamber (A), and the exhaust valve (42) is provided in an upstream exhaust pipe (50) that introduces the combustion gas (G) into the expansion chamber (A).

[0008] A second feature of the present invention is that the combustion gas (G) is introduced into the expansion chamber (A) even when the exhaust valve (42) is closed.

[0009] A third feature is that the exhaust device (30) is attached to a vehicle (1) having a step holder (20) that supports a step bar (19) on which an occupant places his / her feet, and at least a portion of the exhaust valve mechanism (40) overlaps with the step holder (20) in the fore-and-aft direction when viewed from the side of the vehicle body of the vehicle (1).

[0010] A fourth feature is that a cylindrical outer shell member (60) that houses the upstream exhaust pipe (50) is inclined so that the rear side of the vehicle body is located further outward in the vehicle width direction than the front side of the vehicle body when viewed in a plan view of the vehicle (1).

[0011] A fifth feature is that, when viewed from the upstream side of the flow path of the combustion gas (G), the upstream exhaust pipe (50) and the discharge exhaust pipe (55) at least partially overlap each other. Effect of the Invention

[0012] According to a first feature, in an exhaust system (30) having a muffler (34) provided with an expansion chamber (A), an exhaust exhaust pipe (55) for discharging combustion gas (G) from the muffler (34), and an exhaust valve mechanism (40) for adjusting the flow rate of the combustion gas (G) with an open / close exhaust valve (42), the exhaust exhaust pipe (55) is connected to the expansion chamber (A), and the exhaust valve (42) is provided in an upstream exhaust pipe (50) for introducing the combustion gas (G) into the expansion chamber (A). Therefore, by opening the exhaust valve, the combustion gas is introduced into the expansion chamber via the upstream exhaust pipe, and is further discharged to the outside of the muffler from the exhaust exhaust pipe connected to the expansion chamber. Therefore, when the exhaust valve is opened, the combustion gas flows linearly to increase the output of the internal combustion engine, and the combustion gas expands in the expansion chamber to increase the silencing effect.

[0013] According to the second feature, since the exhaust device is configured so that the combustion gas (G) is introduced into the expansion chamber (A) even when the exhaust valve (42) is closed, it is possible to obtain an exhaust device in which the combustion gas is introduced into the expansion chamber regardless of whether the exhaust valve is open or closed. This makes it possible to manufacture exhaust devices having an exhaust valve mechanism and exhaust devices not having an exhaust valve mechanism separately while using many common parts, thereby reducing manufacturing costs.

[0014] According to a third feature, the exhaust device (30) is attached to a vehicle (1) having a step holder (20) that supports a step bar (19) on which an occupant places his / her feet, and at least a portion of the exhaust valve mechanism (40) overlaps with the step holder (20) in the fore-and-aft direction when viewed from the side of the vehicle body of the vehicle (1). Therefore, when viewed from the side of the vehicle body, a valve drive cable extending upward and forward from the exhaust valve device is easily hidden by the step holder, thereby improving the appearance of the vehicle.

[0015] According to a fourth feature, the cylindrical outer shell member (60) that houses the upstream exhaust pipe (50) is inclined so that the rear side of the vehicle body is positioned more outward in the vehicle width direction than the front side in a plan view of the vehicle (1), so that an exhaust valve mechanism can be attached by utilizing the space generated on the inner side in the vehicle width direction by the inclination of the outer shell member. This makes it possible to prevent the exhaust device from becoming large.

[0016] According to the fifth feature, when viewed from the upstream side of the flow path of the combustion gas (G), the upstream exhaust pipe (50) and the exhaust exhaust pipe (55) at least partially overlap each other. Therefore, when an exhaust valve is opened, the combustion gas tends to flow linearly from the upstream exhaust pipe to the exhaust exhaust pipe, thereby obtaining even better output characteristics. [Brief description of the drawings]

[0017] [Figure 1] 1 is a right side view of a motorcycle to which an exhaust device according to an embodiment of the present invention is applied. [Diagram 2] FIG. 2 is a partially enlarged view of FIG. [Diagram 3] FIG. 4 is a left side view showing the internal structure of the muffler. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] 3 is a cross-sectional view taken along line VV in FIG. 2. [Figure 6] 6 is a cross-sectional view taken along line VI-VI in FIG. 2. [Figure 7] FIG. 4 is a left side view showing the internal structure of a muffler that does not have an exhaust valve mechanism. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] A preferred embodiment of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a right side view of a motorcycle 1 to which an exhaust device 30 according to one embodiment of the present invention is applied. Fig. 2 is a partially enlarged view of Fig. 1. The motorcycle 1 is a saddle-ride type vehicle that travels by transmitting the driving force of a power unit P, which is an integral configuration of an internal combustion engine and a transmission, to a rear wheel WR via a drive chain 18.

[0019] A head pipe F1 that rotatably supports a steering stem (not shown) is provided at the front end of a pair of left and right main frames F2 that constitute the body frame F. A top bridge 8 and a bottom bridge 5 that support a pair of left and right front forks 2 are fixed to the upper and lower ends, respectively, of the steering stem.

[0020] A front wheel WF is rotatably supported at the lower end of the front fork 2. A front fender 3 that covers the upper part of the front wheel WF is attached to the front fork 2. A steering handle 10 that supports a pair of left and right rearview mirrors 9 is fixed to the upper part of the top bridge 8. A headlight 4 and a meter device 7 are disposed in front of the head pipe F1.

[0021] A fuel tank 11 is disposed on the upper part of the main frame F2. A pivot frame F3 supporting a pivot 22 that pivotally supports a swing arm 17 so that it can swing freely is connected to the rear end of the main frame F2, which extends rearward and downward from the head pipe F1. A step holder 20 supporting a step bar 19 on which the rider places his / her feet is attached to a position toward the lower side of the pivot frame F3. The step holder 20 includes a heel guard 20a that supports the heels of the rider. A power unit P to which an exhaust device 30 is attached is suspended below the main frame F2 and in front of the pivot frame F3.

[0022] The swing arm 17, which rotatably supports the rear wheel WR, is suspended at a position toward the front from the main frame F2 by a rear cushion 24. A rear frame (not shown) that supports the seat 12 on which the rider sits and the rear cowl 14 in which the taillight unit 15 is embedded is connected to the rear end of the main frame F2. A pair of left and right tandem step holders 13 and a rear fender 16 that covers the upper part of the rear wheel WR are supported on the lower part of the rear cowl 14.

[0023] The exhaust device 30 is composed of an exhaust pipe 31 connected to an exhaust port of the internal combustion engine constituting the power unit P, a catalyst storage section 32 connected to the rear of the exhaust pipe 31, a connecting pipe 33 connected to the rear of the catalyst storage section 32, and a muffler 34 connected to the rear of the connecting pipe 33. The muffler 34 is suspended from the tandem step holder 13 on the right side in the vehicle width direction by an attachment stay 36. A plate-shaped heat guard 35 is attached to the upper part of the muffler 34 to protect the feet of the passenger from heat. An exhaust valve mechanism 40 that adjusts the flow rate of the combustion gas by an open / close exhaust valve is provided in the small diameter section located at the front end of the muffler 34. The exhaust valve mechanism 40 is composed of a rotating shaft 41 that supports an exhaust valve (see FIG. 3).

[0024] In this embodiment, in a side view of the vehicle body, the rear end of the heel guard 20a, which is a part of the step holder 20, is located rearward of the front end of the rotation shaft 41 that supports the exhaust valve. In other words, at least a part of the exhaust valve mechanism 40 is configured to overlap with the step holder 20 in the front-rear direction.

[0025] 3 is a left side view showing the internal structure of muffler 34. The outer shell of muffler 34, which is mainly made up of thin metal plate members and pipe members, consists of a front outer shell 60 that forms a small diameter portion, a tapered outer shell 61 connected to the rear part of front outer shell 60, a large diameter main outer shell 62 connected to the rear part of tapered outer shell 61, and a rear outer shell 63 connected to the rear part of main outer shell 62.

[0026] An upstream exhaust pipe 50 is disposed inside the front shell 60 and the tapered shell 61. A punched pipe 53 having a plurality of through holes is connected to the front end of the upstream exhaust pipe 50, and a connecting member 54 for connecting a muffler 34 to the rear end of the connecting pipe 33 (see FIGS. 1 and 2) is connected to the front end of the punched pipe 53.

[0027] The exhaust valve mechanism 40 makes it possible to adjust the flow rate of the combustion gas G flowing through the upstream exhaust pipe 50 by means of the exhaust valve 42 that opens and closes by the driving force of an actuator. The exhaust valve 42 is a butterfly valve made of a circular thin plate member, and is fixed to a rotating shaft 41 that rotates by the driving force of an actuator.

[0028] A first partition wall 51 having an annular shape is disposed between the upstream exhaust pipe 50 and the front outer shell 60 at a position downstream of the exhaust valve mechanism 40. The first partition wall 51 is provided with a plurality of curved, elongated through-holes 52 through which the combustion gas G passes when the exhaust valve 42 is closed. Meanwhile, a second partition wall 37 having a vertically elongated shape is disposed at a position toward the rear of the tapered outer shell 61. As a result, a front expansion chamber C is formed between the first partition wall 51 and the second partition wall 37.

[0029] The rear end of the upstream exhaust pipe 50 and the front end of the second pipe 57 each penetrate through the second partition 37. A third partition 58 having a vertically elongated shape is disposed inside the main outer shell 62, and a fourth partition 59 having a vertically elongated shape is disposed inside the rear outer shell 63.

[0030] The rear side of the second pipe 57 penetrates the third partition 58 at a position close to the lower side of the main outer shell 62, and extends rearward to a position close to the fourth partition 59. A third pipe 56 extending in the front-rear direction penetrates the third partition 58 at a position close to the upper side, and a front end of an exhaust pipe 55 penetrates approximately the center of the third partition 58. The front end of the third pipe 56 extends forward to a position close to the second partition 37, and the rear end of the third pipe 56 extends rearward to a position close to the fourth partition 59. The rear end of the exhaust pipe 55 penetrates the fourth partition 59 and faces outward from an opening provided in the rear outer shell 63.

[0031] With the above-described configuration, a central expansion chamber A is formed between the second partition 37 and the third partition 58, and a rear expansion chamber B is formed between the third partition 58 and the fourth partition 59. When the exhaust valve 42 is closed during low speed rotation of the internal combustion engine, the combustion gas G passes through the through hole of the punching pipe 53 and flows rearward on the outside of the upstream exhaust pipe 50, and is introduced into the front expansion chamber C through the through hole 52 of the first partition 51.

[0032] Next, the combustion gas G introduced into the front expansion chamber C passes through the second pipe 57 and is introduced into the rear expansion chamber B, and is further introduced into the central expansion chamber A through the third pipe 56. Then, the combustion gas G introduced into the central expansion chamber A passes through the exhaust pipe 55 and is discharged to the outside of the muffler 34.

[0033] On the other hand, when the internal combustion engine is rotating at high speed, etc., and the exhaust valve 42 is opened, the combustion gas G is introduced directly into the central expansion chamber A through the upstream exhaust pipe 50. Then, the combustion gas G introduced into the central expansion chamber A is exhausted to the outside of the muffler 34 through the exhaust exhaust pipe 55. In other words, the combustion gas G introduced from the front of the muffler 34 is mainly discharged through the central expansion chamber A to the rear of the muffler 34.

[0034] Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 2. The same reference numerals as those mentioned above indicate the same or equivalent parts. The upstream exhaust pipe 50 penetrates substantially the center of the second partition wall 37, and the exhaust exhaust pipe 55 (see Fig. 3) is disposed at a position overlapping with the upstream exhaust pipe 50 when viewed from the upstream side of the flow path of the combustion gas G. As a result, when the exhaust valve 42 is opened, the combustion gas G flows linearly from the upstream exhaust pipe 50 to the exhaust exhaust pipe 55, and further improved output characteristics can be obtained.

[0035] 5 is a cross-sectional view taken along line VV in FIG. 2. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. The same reference numerals as those in the above-mentioned drawings indicate the same or equivalent parts. The muffler 34 is disposed on the right side in the vehicle width direction of the motorcycle 1, and the front outer shell 60 constituting the small diameter part of the muffler 34 is disposed at an incline so that the rear side of the vehicle body is positioned more outward in the vehicle width direction than the front side of the vehicle body in a plan view of the vehicle body. The exhaust valve mechanism 40 is attached to the left side in the vehicle width direction of the front outer shell 60. This makes it possible to attach the exhaust valve mechanism 40 by utilizing the space generated on the inner side in the vehicle width direction by the inclination of the front outer shell 60, and thus makes it possible to prevent the exhaust device 30 from becoming large.

[0036] The exhaust valve mechanism 40 includes a rotating shaft 41 to which an exhaust valve 42 is attached, a disk-shaped pulley 47 fixed to the end of the rotating shaft 41, and a return spring 46 that returns the pulley 47 to its initial position (closed state). Two valve drive cables 44, 45 wound around the pulley 47 extend upward and forward from the top surface of a case member 43 that houses the pulley 47 and the return spring 46.

[0037] As described above, the step holder 20 supporting the step bar 19 on which the rider places his / her foot is attached to the rear of the pivot frame F3 on the right side in the vehicle width direction. The brake pedal 21 is pivotally supported on the inner side of the step holder 20 in the vehicle width direction so as to be freely swingable. In this embodiment, the rear end of the heel guard 20a constituting a part of the step holder 20 is located rearward of the front end of the rotation shaft 41 of the exhaust valve 42 in a side view of the vehicle body. In other words, at least a part of the exhaust valve mechanism 40 is configured to overlap the step holder 20 in the front-rear direction. As a result, the valve drive cables 44, 45 extending upward and forward from the case member 43 are easily hidden by the step holder 20 and the heel guard 20a in a side view of the vehicle body, and the appearance of the motorcycle 1 can be improved.

[0038] 7 is a left side view showing the internal structure of the muffler 34a that does not have the exhaust valve mechanism 40. The muffler 34a is configured to accommodate different specifications of the power unit of the same model, without the exhaust valve mechanism 40, while maintaining a common external appearance. With the removal of the exhaust valve mechanism 40, the upstream exhaust pipe 50 is also removed.

[0039] 3 and 4, the shapes and structures of the punching pipe 53a, the front shell 60a, the second partition wall 37a, and the exhaust pipe 55a are slightly different, and the other parts are common to achieve a significant reduction in manufacturing costs. Note that the exhaust pipe 55a according to this embodiment has an extended overall length to adjust the exhaust sound.

[0040] In this muffler 34a, the combustion gas G introduced from the connecting pipe 33 is introduced directly into the front expansion chamber C, then passes through the second pipe 57 into the rear expansion chamber B, and further passes through the third pipe 56 into the central expansion chamber A. Then, the combustion gas G introduced into the central expansion chamber A is discharged to the outside of the muffler 34a through the exhaust pipe 55a.

[0041] As described above, according to the exhaust device 30 of the present invention, the exhaust device 30 has the muffler 34 provided with the central expansion chamber A, the exhaust exhaust pipe 55 that exhausts the combustion gas G from the muffler 34, and the exhaust valve mechanism 40 that adjusts the flow rate of the combustion gas G with the open / close exhaust valve 42. Since the exhaust exhaust pipe 55 is connected to the central expansion chamber A and the exhaust valve 42 is provided in the upstream exhaust pipe 50 that introduces the combustion gas G into the central expansion chamber A, by opening the exhaust valve 42, the combustion gas G is introduced into the central expansion chamber A via the upstream exhaust pipe 50, and is further exhausted to the outside of the muffler 34 from the exhaust exhaust pipe 55 connected to the central expansion chamber A. When the exhaust valve 42 is opened, the combustion gas G flows linearly to increase the output of the internal combustion engine, and the combustion gas G expands in the central expansion chamber A to enhance the silencing effect.

[0042] Furthermore, since the exhaust device 30 is configured so that the combustion gas G is introduced into the central expansion chamber A even when the exhaust valve 42 is closed, it is possible to obtain an exhaust device 30 in which the combustion gas G is introduced into the central expansion chamber A regardless of whether the exhaust valve 42 is open or closed. This makes it possible to separately manufacture the exhaust device 34 having the exhaust valve mechanism 40 and the exhaust device 34a not having the exhaust valve mechanism 40 while using many common parts, thereby reducing manufacturing costs.

[0043] Furthermore, when viewed from the upstream side of the flow path of the combustion gas G, the upstream exhaust pipe 50 and the exhaust exhaust pipe 55 at least partially overlap each other, so that when the exhaust valve 42 is opened, the combustion gas G tends to flow linearly from the upstream exhaust pipe 50 to the exhaust exhaust pipe 55, thereby obtaining even better output characteristics.

[0044] The form of the motorcycle, the number of cylinders of the internal combustion engine, the shape and structure of the exhaust device, the shell and partitions constituting the muffler, the material and shape of the pipe material, the arrangement and structure of the exhaust valve mechanism, the shape and structure of the exhaust valve, the volume ratio of the front expansion chamber, the central expansion chamber and the rear expansion chamber, etc. are not limited to the above embodiment and can be variously modified. For example, the total number of expansion chambers may be four or more. The exhaust device according to the present invention is not limited to motorcycles and can be applied to various vehicles such as three-wheeled vehicles and four-wheeled vehicles that use a power unit including an internal combustion engine as a drive source. [Explanation of symbols]

[0045] Reference Signs List 1...motorcycle (vehicle), 30...exhaust system, 34...muffler, 40...exhaust valve mechanism, 42...exhaust valve, 50...upstream exhaust pipe, 55...discharge exhaust pipe, 51...first partition, 37...second partition, 58...third partition, 59...fourth partition, 57...second pipe, 56...third pipe, 60...front outer shell (outer shell member), A...central expansion chamber (expansion chamber), B...rear expansion chamber, C...front expansion chamber, G...combustion gas

Claims

1. An exhaust system (30) having a muffler (34) provided with an expansion chamber (A), an exhaust pipe (55) for discharging a combustion gas (G) from the muffler (34), and an exhaust valve mechanism (40) for adjusting a flow rate of the combustion gas (G) with an open / close exhaust valve (42), The exhaust exhaust pipe (55) is connected to the expansion chamber (A), The exhaust valve (42) is provided in an upstream exhaust pipe (50) that introduces the combustion gas (G) into the expansion chamber (A).

2. The exhaust system according to claim 1 , wherein the combustion gas (G) is introduced into the expansion chamber (A) even when the exhaust valve (42) is closed.

3. The exhaust device (30) is attached to a vehicle (1) having a step holder (20) that supports a step bar (19) on which a passenger places his / her feet, 3. The exhaust system according to claim 1, wherein at least a portion of the exhaust valve mechanism (40) overlaps with the step holder (20) in a front-rear direction in a side view of the vehicle body of the vehicle (1).

4. 4. The exhaust system according to claim 1, wherein a cylindrical outer shell member (60) that houses the upstream exhaust pipe (50) is inclined so that a rear side of the vehicle body is positioned more outward in the vehicle width direction than a front side of the vehicle body when viewed in a plan view of the vehicle (1).

5. 3. The exhaust system according to claim 1, wherein the upstream exhaust pipe and the discharge exhaust pipe at least partially overlap each other when viewed from the upstream side of the flow path of the combustion gas.

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