JP2019210865A - Exhaust device of saddle riding type vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust device for a saddle type vehicle in which heat and sound are hard to be transmitted from an inner case to an outer case. SOLUTION: The muffler 35 includes an inner case 46 having an expansion chamber EC formed therein, an outer case 48 that covers the inner case 46, and a sound absorbing material 50 that is interposed between the inner case 46 and the outer case 48. I have it. The inner case 46 is formed by joining a pair of inner case halves 46a and 46b, and the outer case 48 is formed by joining a pair of outer case halves 48a and 48b. A through hole 80 is formed in the inner case 46 to connect the expansion chamber EC and the sound absorbing material 50. An inner case 46 and an outer case 48 are joined to an inflow pipe 45 that introduces exhaust gas into the expansion chamber EC. The inner case 46 and the outer case 48 are joined to the outflow pipe 75 that guides the exhaust gas from the expansion chamber EC. [Selection diagram] Fig. 3

Description

  The present invention relates to a dual-structure exhaust device having an inner case and an outer case.

  Some straddle-type vehicles such as motorcycles include a dual-structure exhaust device having an inner case and an outer case (for example, Patent Document 1). Since the exhaust case has a double structure, it is possible to prevent the inner case from being exposed to the outside, so that the inner case does not become a design part and the degree of freedom in design is improved. .

JP, 2006-054082, A

  However, in Patent Document 1, since the outer case is joined to the inner case, the heat of the exhaust gas and the vibration noise of the exhaust gas are easily transmitted from the inner case to the outer case.

  An object of the present invention is to provide an exhaust device for a saddle-ride type vehicle, in which heat and sound are hardly transmitted from an inner case to an outer case.

  In order to achieve the above object, an exhaust device for a saddle-ride type vehicle according to the present invention includes an inner case in which an expansion chamber is formed, an outer case that covers the inner case, the inner case, and the outer case. The inner case is formed by joining a pair of inner case halves, and the outer case is formed by joining a pair of outer case halves, and the inner case The outer case is configured in a non-contact manner, the inner case is formed with a through hole that allows the expansion chamber and the sound absorbing material to communicate with each other, and the inner case and the outer are connected to an inflow pipe that introduces exhaust gas into the expansion chamber. A case is joined, and the inner case and the outer case are joined to an outflow pipe that leads exhaust from the expansion chamber. Here, the “exhaust device” refers to a device in which an expansion chamber is formed to silence the exhaust.

  According to this configuration, since the inner case and the outer case are not in contact with each other, the heat of the exhaust and the vibration sound of the exhaust are not transmitted from the inner case to the outer case. Thereby, while being able to prevent the heat damage by an exhaust apparatus effectively, deterioration of an outer case is suppressed.

  In the present invention, at least one of the inflow pipe and the outflow pipe has a reduced diameter portion that decreases in diameter from the outside of the outer case toward the expansion chamber, and a stepped portion is formed in the reduced diameter portion, The outer case may be joined to the outer surface on the large diameter side of the stepped portion, and the inner case may be joined to the outer surface on the small diameter side of the stepped portion. According to this configuration, an exhaust device in which the inner case and the outer case are not in contact can be formed with a simple configuration.

  In the present invention, a plurality of the expansion chambers may be formed inside the inner case, and the through hole may be formed in a portion other than the most upstream expansion chamber in the inner case. Since the exhaust from the engine first flows into the most upstream expansion chamber, the kinetic energy of the exhaust is large. Therefore, if a punch hole is provided in the most upstream expansion chamber, the sound absorbing material is scattered. According to this configuration, it is possible to obtain a sound absorbing effect by the sound absorbing material while suppressing the scattering of the sound absorbing material.

  When the through hole is formed in a portion other than the most upstream expansion chamber, the inflow pipe is joined to the front portion of the exhaust device, the outflow pipe is joined to the rear portion of the exhaust device, and the expansion chamber is The uppermost upstream first expansion chamber, the downstream second expansion chamber, and the lowermost third expansion chamber are formed at the rear of the exhaust device, and the second expansion chamber. May be formed at a front portion of the exhaust device, and the third expansion chamber may be formed between the first expansion chamber and the second expansion chamber. Since the rear part of the exhaust device is likely to be complicated in shape, it is difficult to make a through hole. However, according to this configuration, a through hole is formed in a portion other than the most upstream first expansion chamber. Can be obtained efficiently.

  When the inflow pipe is joined to the front portion of the exhaust device and the first expansion chamber is formed at the rear portion of the exhaust device, a catalytic converter for purifying exhaust gas is disposed upstream of the exhaust device in the inflow pipe. It may be stored. Although it is preferable that the pipe on the downstream side of the catalytic converter is long, according to this configuration, since the first expansion chamber is in the rear part, the pipe length on the downstream side of the catalytic converter can be increased.

  In the present invention, the inner case is formed by joining the upper inner case half and the lower inner case half, and the outer case is formed by joining the upper outer case half and the lower outer case half. The through hole may be formed in the upper wall and the lower wall of the inner case. According to this configuration, since the inner case and the outer case are configured in a vertically divided structure, the upper wall and the lower wall can be made flat. Since the through hole is provided on such a flat surface, the formation of the through hole is easy.

  When the inner case and the outer case have a vertically split structure, the outer surface of the upper inner case half and the inner surface of the lower inner case half are joined in contact with each other, and the upper outer case half is joined. The outer surface of the lower outer case half and the inner surface of the lower outer case half may be in contact with each other. According to this configuration, both case halves can be joined in a state where the outer surface of the upper case half is fitted into the inner surface of the lower case half, so that assembly is easy.

  In the present invention, the straddle-type vehicle may be a motorcycle, and a drive chain may be disposed on the side of the exhaust device. When the drive chain is arranged on the side of the exhaust device, chain oil may adhere to the outer surface of the outer case. According to this structure, since the temperature rise of an outer case is suppressed, even if chain oil adheres, it is easy to remove.

  According to the exhaust system for a saddle-ride type vehicle of the present invention, it is possible to suppress heat and sound from being transmitted from the inner case to the outer case.

1 is a side view showing a motorcycle that is a kind of saddle riding type vehicle equipped with an exhaust device according to a first embodiment of the present invention. Fig. 3 is a plan view showing an exhaust system of the same motorcycle. It is sectional drawing along the III-III line of FIG. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. It is sectional drawing along the VV line of FIG. It is sectional drawing which shows the connection part of the muffler and inflow pipe of the same motorcycle. It is sectional drawing which shows the connection part of the same muffler and an outflow pipe.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, “upstream” and “downstream” refer to “upstream” and “downstream” in the exhaust flow direction. FIG. 1 is a side view showing a motorcycle which is a kind of saddle riding type vehicle equipped with an exhaust device according to a first embodiment of the present invention. The body frame FR of the motorcycle has a main frame 1 constituting the front half and a rear frame 2 constituting the rear half of the body frame FR. The rear frame 2 is connected to the rear portion of the main frame 1.

[Overall structure of vehicle]
A front fork 4 is supported at the front end of the main frame 1, and a front wheel 6 is supported at the lower end of the front fork 4. A handle 8 is attached to the upper end of the front fork 4. A swing arm bracket 10 is formed at the lower rear end of the main frame 1. A front end of a pair of left and right swing arms 12 is supported by the swing arm bracket 10 via a pivot shaft 14 so as to be swingable up and down. A rear wheel 16 is supported at the rear end of the swing arm 12. An engine E is supported at the lower center of the main frame 1. The engine E drives the rear wheel 16 via the drive chain 18.

  A rider's seat 20 and a passenger's seat 22 are supported on the rear frame 2. A fuel tank 24 is attached to the upper part of the main frame 1 between the handle 8 and the rider's seat 20.

  The engine E of the present embodiment is a 4-cylinder 4-cycle engine in which cylinders are arranged in the vehicle width direction. However, the format of the engine E is not limited to this. The engine E includes a crankcase 26 that supports a crankshaft (not shown), a cylinder 28 that protrudes upward from the crankcase 26, and a cylinder head 30 above the cylinder 28.

  Four exhaust pipes 32 are connected to an exhaust port (not shown) on the front surface of the cylinder head 30. The exhaust pipes 32 are gathered at a gathering portion 34 below the engine E after extending downward on the front side of the engine E. A muffler 35, which is a kind of exhaust device, is connected to the downstream end (rear end) of the collecting portion 34. The muffler 35 silences the exhaust. A tail pipe 36 is connected to the rear end of the muffler 35.

  The muffler 35 of the present embodiment is disposed between the rear surface of the engine E and the rear wheel 16. A support bracket 38 is joined to the upper surface of the muffler 35. The muffler 35 is supported on the lower end portion of the swing arm bracket 10 via a support bracket 38. In the present embodiment, the drive chain 18 is disposed above the muffler 35 in a side view of FIG. 1 and is disposed on the side of the muffler 35 in a plan view shown in FIG.

  The collecting portion 34 includes an exhaust manifold 41 at the upstream end, a catalyst pipe 43 at the downstream side, and an inflow pipe 45 at the downstream end. In the exhaust manifold 41, four exhaust pipes 32 are assembled. Specifically, the four exhaust pipes 32 are merged into two and further merged into one. However, the four exhaust pipes 32 may be gathered into one gathering portion 34. An oxygen sensor 40 is provided in the exhaust manifold 41. The oxygen sensor 40 detects the oxygen concentration in the exhaust. Specifically, the oxygen sensor 40 detects the oxygen concentration in the exhaust gas after being merged into one.

  A catalyst tube 43 is connected to the downstream end (rear end) of the exhaust manifold 41. A catalytic converter 42 is housed inside the catalyst tube 43. The catalytic converter 42 renders harmful exhaust components such as hydrocarbons and carbon monoxide contained in the exhaust gas harmless. In the present embodiment, two catalytic converters 42 are provided along the exhaust flow direction. However, the number of catalytic converters 42 may be one or three or more. Further, the catalytic converter 42 may be housed in the muffler 35.

  An inflow pipe 45 is connected to the downstream end (rear end) of the catalyst pipe 43. Specifically, the pipes 43 and 45 are connected to each other with the rear part of the catalyst pipe 43 fitted into the inflow pipe 45. A downstream end (rear end) of the inflow pipe 45 opens into the muffler 35. That is, the inflow pipe 45 introduces exhaust into the muffler 35. The inflow pipe 45 is joined to the front part of the muffler 35. Details of the structure of the inflow pipe 45 will be described later.

  The outer side (right side) of the muffler 35 is covered with a muffler cover 44. Specifically, the mounting bracket 35a is joined to the right side surface of the muffler 35, and the muffler cover 44 is detachably mounted to the mounting bracket 35a using a fastening member 47. The muffler cover 44 of the present embodiment covers an area from the front-rear direction intermediate portion to the rear end portion of the muffler 35 and the front portion of the tail pipe 36 from the outer side (right side).

[Muffler structure]
A reinforcing rib 39 is formed on the outer surface of the muffler 35. The reinforcing rib 39 is provided to prevent the outer wall of the muffler 35 from resonating due to exhaust. The reinforcing rib 39 of the present embodiment has a groove shape in which the outer surface of the muffler 35 is recessed inward, and extends in a band shape over the upper surface, the inner surface, and the lower surface. A plurality of reinforcing ribs 39 (five in this embodiment) are provided side by side in the front-rear direction. However, the shape and number of the reinforcing ribs 39 are not limited to this. Further, the reinforcing rib 39 may be omitted.

  3 is a sectional view taken along line III-III in FIG. 2, FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, and FIG. 5 is a sectional view taken along line V-V in FIG. As shown in FIG. 3, the muffler 35 is interposed between an inner case 46 in which an expansion chamber EC is formed, an outer case 48 that covers the outer side of the inner case 46, and the inner case 46 and the outer case 48. Sound absorbing material 50. In the present embodiment, the inner case 46 and the outer case 48 are made of stainless steel. However, the material of the inner case 46 and the outer case 48 is not limited to this.

  The muffler 35 is a so-called “middle structure” configured by integrating the upper case half and the lower case half by welding. The muffler 35 has an upper surface extending rearward and a tail pipe 36 is connected to the rear end. As described above, the muffler 35 has a complicated shape particularly at the rear portion, but can be molded because it has a “main structure”. As shown in FIG. 5, the inner case 46 is formed by joining an upper inner case half 46a and a lower inner case half 46b, and the outer case 48 includes an upper outer case half 48a and a lower outer case 46a. It is formed by joining the case half 48b.

  The inner case 46 is joined with the outer surface of the upper inner case half 46a and the inner surface of the lower inner case half 46b in contact with each other. Similarly, the outer case 48 is joined with the outer surface of the upper outer case half 48a and the inner surface of the lower outer case half 48b in contact with each other.

  The sound absorbing material 50 is also composed of a two-piece molded body. Specifically, the sound absorbing material 50 includes an upper molded body 50a and a lower molded body 50b. The sound absorbing material 50 has heat resistance, impact resistance, and attenuation. The sound absorbing material 50 of this embodiment is glass wool. However, the sound absorbing material 50 is not limited to glass wool, and may be, for example, a suspension mesh or an aluminum foil. The assembly structure of the muffler 35 will be described later.

  As shown in FIG. 3, in the present embodiment, three expansion chambers 52, 54, and 56 are formed inside the inner case 46. Specifically, the inner case 46 is partitioned into three chambers in the front-rear direction by the first and second partition walls 58, 60, and the most upstream first expansion chamber 52 is formed at the rearmost, A second expansion chamber 54 is formed in the front, and a third expansion chamber 56 on the most downstream side is formed in the middle. However, the number and arrangement of the expansion chambers are not limited to this.

  As shown in FIG. 4, the first expansion chamber 52 is formed between the second partition wall 60 and the rear wall 46 r of the inner case 46. The second expansion chamber 54 is formed between the front wall 46 f of the inner case 46 and the first partition wall 58. The third expansion chamber 56 is formed between the first partition wall 58 and the second partition wall 60. The first partition wall 58 and the second partition wall 60 are joined to the inner wall of the inner case 46.

  An introduction pipe 62 of the muffler 35 is connected to the inflow pipe 45 at the downstream end of the collecting portion 34. Specifically, the inflow pipe 45 has a reduced diameter portion 69 that decreases in diameter from the outside of the outer case 48 of the muffler 35 toward the expansion chamber EC. A stepped portion 70 is formed in the reduced diameter portion 69. A large diameter portion 72 is formed on the upstream side (front side) with the stepped portion 70 interposed therebetween, and a small diameter portion 74 is formed on the downstream side (rear side). The upstream end of the introduction pipe 62 is press-fitted into the inner surface of the downstream end 45 a of the inflow pipe 45. If there is no problem in assembly, the inflow pipe 45 and the introduction pipe 62 may be formed of a single member.

  The introduction pipe 62 passes through the front wall 48 f of the outer case 48, the front wall 46 f of the inner case 46, the first partition wall 58, and the second partition wall 60, and opens into the first expansion chamber 52. In other words, the introduction pipe 62 passes through the second expansion chamber 54 and the third expansion chamber 56 to connect the inside of the collecting portion 34 and the first expansion chamber 52. The introduction pipe 62 is fixed to the first partition wall 58 and the second partition wall 60 by press fitting.

  A first communication pipe 64 that penetrates through the second partition wall 60 and the first partition wall 58 and connects the first expansion chamber 52 and the second expansion chamber 54 is provided. One end (upstream end) of the first communication pipe 64 opens into the first expansion chamber 52, passes through the third expansion chamber 56, and the other end (downstream end) opens into the second expansion chamber 54. The first communication pipe 64 is fixed to the second partition wall 60 by welding and is fixed to the first partition wall 58 by press fitting.

  A second communication pipe 66 is provided through the first partition wall 58 to allow the second expansion chamber 54 and the third expansion chamber 56 to communicate with each other. The second communication pipe 66 has one end (upstream end) opened to the second expansion chamber 54 and the other end (downstream end) opened to the third expansion chamber 56. The second communication pipe 66 is fixed to the first partition wall 58 by welding. Instead of the second communication pipe 66, an opening may be provided in the first partition wall 58 to allow the second expansion chamber 54 and the third expansion chamber 56 to communicate with each other.

  A lead-out pipe 68 connected to the tail pipe 36 is provided through the second partition wall 60, the rear wall 46 r of the inner case 46 and the rear wall 48 r of the outer case 48. One end (upstream end) of the outlet pipe 68 opens into the third expansion chamber 56, passes through the first expansion chamber 52, and the other end (downstream end) is connected to the tail pipe 36. That is, the outlet pipe 68 communicates the third expansion chamber 56 and the inside of the tail pipe 36. The outlet pipe 68 is fixed to the second partition wall 60 by welding. In the present embodiment, the outlet pipe 68 and the tail pipe 36 constitute an outflow pipe 75 that guides exhaust gas from the expansion chamber EC. If there is no problem in assembly, the outlet pipe 68 and the tail pipe 36 may be formed of a single member.

  The inner case 46 and the outer case 48 are configured in a non-contact manner. Specifically, the inner case 46 and the outer case 48 are joined to the inflow pipe 45, and the inner case 46 and the outer case 48 are joined to the outflow pipe 75. That is, the inner case 46 and the outer case 48 are connected via the inflow pipe 45 and the outflow pipe 75, but are not connected at other locations. Specifically, the inner case 46 and the outer case 48 are in contact with each other through the sound absorbing material 50 at locations other than the inflow pipe 45 and the outflow pipe 75, and are not in direct contact with each other.

  The inflow pipe 45 is joined to the front wall 48f of the outer case 48 and the front wall 46f of the inner case 46 by welding. Specifically, as shown in FIG. 6, the outer case 48 is joined to the outer surface of the large diameter portion 72 of the stepped portion 70 of the inflow pipe 45, and the inner case 46 is joined to the outer surface of the small diameter portion 74 of the stepped portion 70. Yes. In the present embodiment, the inflow pipe 45, the outer case 48, and the inner case 46 are directly joined, but may be joined indirectly via a connecting member.

  As shown in FIG. 7, the outflow pipe 75 is joined to the rear wall 46r of the inner case 46 and the rear wall 48r of the outer case 48 by welding. Specifically, the rear wall 46 r of the inner case 46 is joined to the outer peripheral surface of the outlet pipe 68 in the outflow pipe 75 via an annular connecting member 76. In the present embodiment, the connecting member 76 is joined to the rear wall 46 r of the inner case 46 by welding, and the outlet pipe 68 is press-fitted to the inner peripheral surface of the connecting member 76.

  In the outflow pipe 75, the downstream end of the outlet pipe 68 is press-fitted into the inner peripheral surface of the tail pipe 36. A rear wall 48r of the outer case 48 is joined to the outer peripheral surface of the tail pipe 36 by welding. In the present embodiment, the connecting member 76 is joined to the rear wall 46 r of the inner case 46 by welding, and the outlet pipe 68 is press-fitted to the inner peripheral surface of the connecting member 76.

  A stepped portion 78 is formed at the upstream end (front end) of the tail pipe 36, the outlet pipe 68 is press-fitted into the front side (upstream side) of the stepped portion 78, and the outer case 48 is joined to the rear side (downstream side). Yes. That is, the outer case 48 is joined to the outer surface on the large diameter side downstream of the stepped portion 78 in the outflow pipe 75, and the inner case 46 is joined to the outer surface on the small diameter side upstream of the stepped portion 78. In the present embodiment, the joining structure to the muffler 35 is different between the inflow pipe 45 side shown in FIG. 6 and the outflow pipe 75 side shown in FIG. 7, but may be the same.

  As shown in FIG. 4, a large number of through holes 80 are formed in the inner case 46 to allow the expansion chamber EC and the sound absorbing material 50 to communicate with each other. In the present embodiment, the through hole 80 is formed in a portion other than the most upstream first expansion chamber 52 in the inner case 46. As shown in FIG. 3, in the present embodiment, the through holes 80 are formed in the upper wall and the lower wall of the inner case 46. However, the through holes 80 may be provided in walls other than the upper wall and the lower wall in the inner case 46. The through hole 80 is composed of, for example, a plurality of punch holes.

[Assembly of muffler]
Next, an assembling method of the inner case 46 and the outer case 48 of the present embodiment will be described. First, partition walls 58 and 60 and pipes 62, 64, 66 and 68 are arranged / fixed in the inner case 46 shown in FIG. 68 is press-fitted. In this state, the inner case 46 is joined to the inflow pipe 45 and the outflow pipe 75, and the upper inner case half 46a and the lower inner case half 46b are joined.

  Further, the upper outer case half 48a and the lower outer case half 48b of the outer case 48 in a state where the upper molded body 50a and the lower molded body 50b of the sound absorbing material 50 are interposed on the outer surface of the inner case 46. And put it on. In this state, the outer case 48 is joined to the inflow pipe 45 and the outflow pipe 75, and the upper outer case half 48a and the lower outer case half 48b are joined. At this time, the sound absorbing material 50 is pressed and compressed on the inner surface of the outer case 48 and is uniformly disposed in the space between the cases 46 and 48 without a gap. As described above, the muffler 35 is assembled.

[Exhaust flow]
Next, the flow of exhaust in the present embodiment will be described. When the engine E shown in FIG. 1 starts and the motorcycle travels, the exhaust G burned in the cylinder 28 of the engine E is led to the exhaust pipe 28. The exhaust G is collected by the collecting portion 34 shown in FIG. 2 and then purified through the catalytic converter 42.

  The exhaust G that has passed through the catalytic converter 42 flows into the first expansion chamber 52 of the muffler 35 from the introduction pipe 62 shown in FIG. The exhaust G expands in the first expansion chamber 52 and then flows into the second expansion chamber 54 from the first communication pipe 64. The exhaust G expands in the second expansion chamber 54 and is absorbed by coming into contact with the sound absorbing material 50 through the through holes 80. The exhaust G in the second expansion chamber 54 flows from the second communication pipe 66 into the third expansion chamber 56.

  The exhaust G expands in the third expansion chamber 56 and is absorbed by contacting the sound absorbing material 50 through the through holes 80. The exhaust G in the third expansion chamber 56 is discharged to the outside from the outlet pipe 68 through the tail pipe 36. In this way, the exhaust G is muffled by repeatedly expanding and contracting inside the muffler 35, and is muffled by the sound absorbing material 50.

[Action / Effect]
As shown in FIG. 3, the muffler 35 having the above-described configuration has a double “middle structure”, and thus has high rigidity and can suppress vibration and resonance of the outer case 48. Moreover, since the through hole 80 is provided in the inner case 46 and the exhaust gas G is silenced by the sound absorbing material 50, the silencing effect is great.

  In general, in the double “mona structure” muffler 35, a boss (support member) is erected on one case and the other case is welded to the boss. Providing such a support member complicates the configuration of the muffler 35 and also requires a hole in the sound absorbing material 50. Further, the heat of the inner case 46 is transmitted to the outer case 48 through the support member, and the outer case 48 is easily heated and deteriorated.

  According to the above configuration, the inner case 46 and the outer case 48 are not in direct contact with each other. That is, since the inner case 46 and the outer case 48 are not in contact with each other, the heat of the exhaust G and the vibration sound of the exhaust are not transmitted from the inner case 46 to the outer case 48. Thereby, while being able to prevent the heat damage by the muffler 35 effectively, deterioration of the outer case 48 is suppressed.

  The inflow pipe 45 has a reduced diameter portion 69 that is reduced in diameter from the outside of the outer case 48 toward the expansion chamber EC, and the outer case 48 is joined to a large diameter portion 72 of the stepped portion 70 in the reduced diameter portion 69. The inner case 46 is joined to the small diameter portion 74 of the portion 70. Thereby, it is possible to realize a structure in which the inner case 46 and the outer case 48 are not in contact with each other with a simple configuration.

  A rear portion of the catalyst pipe 43 in which the catalytic converter 42 is accommodated is fitted inside the upstream end of the inflow pipe 45. The straight pipe portion on the downstream side of the catalytic converter 42 is preferably long. In the present embodiment, since the introduction pipe 62 extends from the front end of the muffler 35 to the rear part, a sufficient length can be secured. Moreover, since the rear part of the catalyst pipe 43 is fitted inside the upstream part (front part) of the inflow pipe 45, the upstream part (front part) of the inflow pipe 45 has a large diameter. On the other hand, since the introduction pipe 62 passes through the second expansion chamber 54 and the third expansion chamber 56, the introduction pipe 62 has a small diameter so that the space of each of the expansion chambers 54, 56 is not narrowed. For this reason, the inflow pipe 45 is formed with a reduced diameter portion 69 that decreases in diameter from the outside of the outer case 48 toward the expansion chamber EC. In the above embodiment, such a reduced diameter portion 69 is used to realize a structure in which the cases 46 and 48 are not in contact with each other.

  Further, a through hole 80 is formed in a portion other than the first expansion chamber 52 on the wall surface of the inner case 46. Since the exhaust G from the engine E first flows into the most upstream first expansion chamber 52, the kinetic energy of the exhaust G is large. Therefore, if a through hole is provided in the most upstream first expansion chamber 52, the sound absorbing material 50 is scattered due to a large impact of the exhaust G. According to the above configuration, since there is no through hole 80 in the wall surface of the first expansion chamber 52 with large exhaust energy, the sound absorbing effect by the sound absorbing material 50 can be obtained while the scattering of the sound absorbing material 50 is suppressed.

  The rear part of the muffler 35 has a complicated shape and it is difficult to open the through hole 80. However, in the above configuration, the through hole 80 is formed in a portion other than the first expansion chamber 52 at the rear part. Therefore, the sound absorption effect by the sound absorbing material 50 can be obtained efficiently.

  The through holes 80 are provided in the upper and lower walls of the inner case 46 and the outer case 48. Since the inner case 46 and the outer case 48 have a vertically divided structure, the upper wall and the lower wall can be flat. Since the through hole 80 is provided on such a flat surface, the formation of the through hole 80 is easy. Further, since the exhaust G flows into the second and third expansion chambers 54 and 56 from the front-rear direction, the exhaust G does not directly hit the upper wall and the lower wall.

  As shown in FIG. 5, the inner case 48 is joined in a state in which the outer surface of the upper inner case half 48a and the inner surface of the lower inner case half 46b are in contact with each other. Similarly, the outer case 48 is joined with the outer surface of the upper outer case half 48a and the inner surface of the lower outer case half 48b in contact with each other. As described above, both case halves 46 and 48 can be joined in a state in which the outer surfaces of the upper case halves 46a and 48a are fitted into the inner surfaces of the lower case halves 46b and 48b. .

  As shown in FIG. 2, the drive chain 18 is disposed on the side of the muffler 35. In this case, the chain oil may adhere to the outer surface of the outer case 48. However, according to the above configuration, since the temperature rise of the outer case 48 is suppressed, the chain oil may adhere to the outer surface of the outer case 48. Easy to remove.

  The present invention is not limited to the above-described embodiments, and various additions, modifications, or deletions can be made without departing from the gist of the present invention. For example, in the above embodiment, the example in which the present invention is applied to the muffler 35 disposed at the downstream end of the exhaust passage has been described. However, the exhaust apparatus of the present invention has an expansion chamber formed therein and silences the exhaust. Applicable in general. For example, the exhaust device of the present invention can be applied to an exhaust chamber disposed on the upstream side of the muffler. Therefore, such a thing is also included in the scope of the present invention.

18 Drive chain 35 Muffler (exhaust device)
42 Catalytic converter 45 Inflow pipe 46 Inner case 46a Upper inner case half (inner case half)
46b Lower inner case half (inner case half)
48 Outer case 48a Upper outer case half (outer case half)
48b Lower outer case half (outer case half)
50 Sound absorbing material 52 First expansion chamber 54 Second expansion chamber 56 Third expansion chamber 69 Reduced diameter portion 70 Stepped portion 75 Outflow pipe 80 Through hole EC Expansion chamber

Claims (8)

An inner case in which an expansion chamber is formed;
An outer case covering the inner case;
A sound absorbing material interposed between the inner case and the outer case,
The inner case is formed by joining a pair of inner case halves, and the outer case is formed by joining a pair of outer case halves,
The inner case and the outer case are configured to be non-contact,
A through hole is formed in the inner case to communicate the expansion chamber and the sound absorbing material,
The inner case and the outer case are joined to an inflow pipe for introducing exhaust gas into the expansion chamber,
An exhaust system for a saddle-ride type vehicle, wherein the inner case and the outer case are joined to an outflow pipe for exhausting air from the expansion chamber. 2. The exhaust device according to claim 1, wherein at least one of the inflow pipe and the outflow pipe has a reduced diameter portion that decreases in diameter from the outside of the outer case toward the expansion chamber,
A stepped portion is formed in the reduced diameter portion,
An exhaust system for a saddle-ride type vehicle, wherein the outer case is joined to an outer surface on the large diameter side of the stepped portion, and the inner case is joined to an outer surface on the small diameter side of the stepped portion. The exhaust device according to claim 1 or 2, wherein a plurality of the expansion chambers are formed inside the inner case,
An exhaust system for a saddle-ride type vehicle in which the through hole is formed in a portion other than the most upstream expansion chamber in the inner case. The exhaust device according to claim 3, wherein the inflow pipe is joined to a front portion of the exhaust device, and the outflow pipe is joined to a rear portion of the exhaust device,
The expansion chamber is composed of a most upstream first expansion chamber, a downstream second expansion chamber, and a most downstream third expansion chamber,
The first expansion chamber is formed at the rear portion of the exhaust device, the second expansion chamber is formed at the front portion of the exhaust device, and the third expansion chamber is between the first expansion chamber and the second expansion chamber. An exhaust device for a saddle-ride type vehicle formed in   5. The exhaust system according to claim 4, wherein a catalytic converter for purifying exhaust gas is housed upstream of the exhaust system in the inflow pipe. 6. The exhaust device according to claim 1, wherein the inner case is formed by joining an upper inner case half and a lower inner case half, and the outer case is an upper outer case half. Formed by joining the body and the lower outer case half,
An exhaust system for a saddle-ride type vehicle, wherein the through hole is formed in an upper wall and a lower wall of the inner case.   The exhaust device according to claim 6, wherein the outer surface of the upper inner case half and the inner surface of the lower inner case half are joined in contact with each other, and the outer surface of the upper outer case half and the lower side are joined. An exhaust device for a saddle-ride type vehicle that is joined in contact with the inner surface of the outer case half. The exhaust system according to any one of claims 1 to 7, wherein the straddle-type vehicle is a motorcycle, and a drive chain is disposed on a side of the exhaust system.

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