JP4381916B2 - Silencer for internal combustion engine of motorcycle - Google Patents

Description

The present invention relates to a silencer for an internal combustion engine of a motorcycle .

Conventionally, as a silencer for an internal combustion engine, the cylindrical body has a double structure including an outer cylinder and an inner cylinder, and a space formed by using a gap between the cylinders is configured as a vacuum layer. Thus, there is one that suppresses the propagation of exhaust noise to the outside of the cylinder and improves the silencing performance (see, for example, Patent Document 1).
JP-A-61-294114

However, the silencer has a problem that the structure is complicated because the front and rear ends of the cylinder are divided to improve the silencing performance.
In addition, in the case of a silencer for an internal combustion engine applied to a vehicle, it is necessary to consider the exhaust sound quality in addition to the silencing performance. A configuration that can be expanded is expected.
Accordingly, the present invention provides a silencer for an internal combustion engine of a motorcycle that can simplify the structure, improve the noise reduction performance, and can widen the adjustment range of the exhaust sound quality.

As a means for solving the above problems, the invention described in claim 1 is an internal combustion engine in which a muffler chamber (for example, each chamber 45a, 45b, 45c of the embodiment) is formed in a cylinder (for example, the cylinder 42 of the embodiment). In the engine silencer (for example, the muffler device 40 of the embodiment), the cylinder body has at least a triple cylinder member (for example, the outer cylinder 51, the intermediate cylinder 52, and the inner cylinder 53 of the embodiment) on the inside and outside thereof. Further, at least two layers of space portions (for example, the space portions 54 and 55 in the embodiment) are formed by utilizing the gaps between the cylindrical members, and at least one of these space portions is formed as a vacuum layer (for example, the vacuum in the embodiment). Layer 54A), and at least one other is a sound-absorbing and heat-insulating material-filled layer (for example, the glass wool-filled layer 55A of the embodiment), and the vacuum layer is disposed on the outer peripheral side of the sound-absorbing and heat-insulating material-filled layer A cylindrical member on the outer peripheral side of the cylindrical body ( Example, if it was attached to the outer cylinder 51) to the seat frame of the embodiment (e.g. coupling member between the seat frame 9) Example (eg joint stay 56 in the embodiment) directly and said.

According to this configuration, it is possible to improve the noise reduction and heat insulation performance by suppressing the exhaust noise and heat propagation with the two layers of the vacuum layer and the sound absorbing heat insulating material filling layer.
Moreover, it is possible to widen the adjustment range of the exhaust sound quality by providing different sound deadening characteristics to the vacuum layer and the sound absorbing heat insulating material filling layer.
Furthermore, according to this configuration, it is possible to effectively suppress the temperature rise on the outer peripheral side by blocking the propagation of the exhaust heat itself on the outer peripheral side of the cylindrical body.
At this time, even if it is the structure which attached the connection member with a seat frame directly to the cylinder member of the outer peripheral side of the said cylinder, it can prevent that this connection member becomes high temperature.

In the invention described in claim 2 , the vacuum layer is arranged on the outer peripheral side of the cylindrical body, and the cylindrical member that forms the vacuum layer (for example, the outer cylinder 51 of the embodiment) is a single member. Features.
According to this configuration, the seam of the cylindrical member does not appear on the outer surface of the cylindrical body, and the airtightness of the vacuum layer can be easily ensured.

Here, as in the invention described in claim 3, it may be configured to be placed the silencer beneath (pillion seat 20 in the Examples) sheet.
That is, by arranging the silencer under the seat of the vehicle, the vehicle body width is narrowed and the propagation of exhaust heat to the seat is suppressed.

According to the first aspect of the present invention, it is not necessary to make the front and rear end portions of the cylindrical body divided as in the prior art, and the structure can be simplified. In addition, the product quality can be improved by widening the adjustment range of the exhaust sound quality.
Further , according to the present invention, it is not necessary to take measures against heat around the cylindrical body, and it is possible to improve the degree of design freedom by reducing the size and weight.
According to the second aspect of the present invention, the appearance can be improved and the product quality can be improved, and the airtightness can be easily secured to reduce the number of manufacturing steps.
According to the third aspect of the present invention, it is possible to provide a vehicle body structure in which the temperature rise of the seat is suppressed while narrowing the vehicle body width, and it is possible to reduce cost and weight by eliminating the need for a heat insulating cover or the like.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the directions such as front, rear, left and right in the following description are the same as those in the vehicle unless otherwise specified. In the figure, the arrow FR indicates the front of the vehicle, the arrow LH indicates the left side of the vehicle, and the arrow UP indicates the upper side of the vehicle.

  As shown in FIG. 1, a front fork 3 that pivotally supports a front wheel 2 of a motorcycle (vehicle) 1 is pivotally supported by a head pipe 6 provided at a front end portion of a vehicle body frame 5 via a steering stem 4 so as to be steerable. The A main frame 7 of the vehicle body frame 5 extends obliquely downward and rearward from the head pipe 6, and a rear end portion thereof is bent downward to be connected to the pivot plate 8. Further, a front end portion of a seat frame 9 extending obliquely upward and rearward is connected to the rear portion of the main frame 7.

  A pivot arm 8 is pivotally attached to the pivot plate 8 via a pivot shaft 11, and a rear wheel 12 is pivotally supported at the distal end of the swing arm 13. The upper end of the cushion unit 14 is attached to the upper part of the base end side of the swing arm 13, and the lower end of the cushion unit 14 is connected to the pivot plate 8 at a position below the pivot shaft 11 via the link mechanism 15. .

  A fuel tank cover 17 is mounted above the main frame 7, and a water-cooled in-line four-cylinder engine (internal combustion engine) 18 is mounted below the main frame 7. A driver seat 19 and a rear passenger pillion seat 20 are provided behind the fuel tank cover 17. A driver step 21 is attached to the rear part of the pivot plate 8, and a rear passenger step 22 is attached to the lower part of the seat frame 9. Inside the fuel tank cover 17, an air cleaner case 34 is disposed at the front thereof, and a fuel tank body 17a is disposed at the rear thereof.

  A handle 23 is attached to the upper end of the front fork 3. A brake caliper 24 is attached to the lower end portion of the front fork 3 via a caliper bracket, and a brake disc 25 corresponding to the brake caliper 24 is attached to the hub portion of the front wheel 2 so that the front disc brake of the motorcycle 1 is attached. 26 is configured. A rear disc brake (not shown) having the same configuration as that of the front disc brake 26 is provided on the right side of the rear wheel 12.

  The front part of the motorcycle 1 is covered with a front cowl 27, and the periphery of the seat frame 9 is covered with a rear cowl 28. A rear sprocket 29 is attached to the left side of the rear wheel 12, and a drive chain 31 is wound around the rear sprocket 29 and a drive sprocket 30 disposed on the left side of the rear portion of the engine 18. It is transmitted to the wheel 12.

  A downstream side of the throttle body 33 corresponding to each cylinder is connected to the upper rear side of the cylinder head 32 of the engine 18, and an upstream side of each throttle body 33 is connected to the air cleaner case 34. An exhaust pipe 35 corresponding to each cylinder is connected to the front portion of the cylinder head 32, and a radiator 38 for cooling the engine 18 is disposed in front of the exhaust pipe 35. The exhaust pipe 35 is curved downward from the front part of the cylinder head 32 and extends rearward below the crankcase 36. The exhaust pipe 35 is further bent upward in the vicinity of the seat frame 9 after being bent upward at the rear of the pivot plate 8. Bend backward. Such a rear end portion of the exhaust pipe 35 is connected to a front end portion of a muffler device (a silencer for an internal combustion engine) 40 supported by the seat frame 9 in the rear cowl 28.

  As shown in FIGS. 2, 3, and 4, the muffler device 40 has a main appearance formed by a cylinder body 42 having a muffler main body 41 extending substantially linearly along an axis C, and in a lateral direction (vehicle width direction). It has a wide irregular cross-sectional shape. Such a muffler device 40 is disposed in the rear cowl 28 in a posture in which the axis C is inclined slightly forward and downward (see FIG. 1). 2 to 4 indicate the forward direction in the direction along the axis C, and the arrow UP 'indicates the upper direction in the direction perpendicular to the axis C in a side view.

  The muffler main body 41 is provided with a front cap 43 and an end cap 44 at the front and rear end portions of the cylindrical body 42, respectively, and in the internal space formed by the front cap 43 and the end cap 44, the space serves as a chamber for three mufflers in the front-rear direction. (Expansion chambers) Two separators (partition walls) 46 and 47 partitioned into 45a, 45b and 45c are disposed, and three communication pipes 48a, 48b and 48c for appropriately communicating the respective chambers 45a, 45b and 45c are disposed. It has a basic configuration.

  The rear part of the cylindrical body 42 has a tapered shape in which both side parts and the lower part are inclined so as to reduce toward the rear. Hereinafter, the rear portion of the cylindrical body 42 will be described as a tapered portion 42b, and the front portion thereof will be described as a straight portion 42a. Such a cylindrical body 42 is arranged with an outer cylinder 51 forming an outer peripheral surface thereof, an intermediate cylinder 52 arranged with a predetermined gap inside thereof, and further with a predetermined gap inside thereof. A triple structure with the inner cylinder 53.

  And the outer peripheral side space part 54 formed between the outer cylinder 51 and the intermediate | middle cylinder 52 is comprised as a vacuum layer 54A by the evacuation in the muffler main body 41 manufacturing process. Further, the inner circumferential side space portion 55 formed between the intermediate cylinder 52 and the inner cylinder 53 is configured as a glass wool filled layer 55A filled with glass wool (sound absorbing heat insulating material) G in the same muffler body 41 manufacturing process. .

  A U-shaped connecting stay 56 that opens upward is joined to the upper portion of the outer cylinder 51 by welding or the like via a reinforcing patch 56a. The muffler device 40 is supported by the seat frame 9 of the motorcycle 1 through the connecting stay 56. It can be said that such a connecting stay 56 is directly attached to the cylindrical body 42 without using a heat insulating material or the like.

  The front cap 43 is inclined obliquely from the front end of the cylindrical body 42 toward the front of the lower right in order to connect the rear end portion of the exhaust pipe 35 extending from the lower right front of the muffler body 41 and the front end of the cylindrical body 42. It is bent and extended, and has a diffuser shape formed so as to expand from the front end side toward the rear end side. The front end of the front cap 43 circumscribes the rear end of the exhaust pipe 35 and is joined over the entire circumference by welding or the like, and the rear end of the front cap 43 is the front end of the cylindrical body 42 (in detail). Is inscribed in the intermediate cylinder 52) and joined over the entire circumference by welding or the like.

  The end cap 44 has a double structure including an end plate 57 disposed so as to be orthogonal to the axis C and a guide plate 64 disposed in front of the end plate 57 with a predetermined gap (inside the cylindrical body 42). . An outer peripheral wall that rises rearward is formed over the entire outer periphery of each of the plates 57 and 64, and the outer peripheral wall of the end plate 57 is inscribed in the outer peripheral wall of the guide plate 64 and is appropriately joined by welding or the like. At the same time, the outer peripheral wall of the guide plate 64 is inscribed in the rear end portion of the cylindrical body 42 (specifically, inscribed so as to straddle the rear end portions of the inner cylinder 53 and the intermediate cylinder 52), and is welded over the entire circumference. Be joined. A reinforcing bead is appropriately formed on each of the plates 57 and 64. A pair of left and right rear stays 59 for fixing the muffler end cover 58 is attached to the rear surface side of the end plate 57.

  The separators 46 and 47 are disposed so as to be orthogonal to the axis C at the front and rear portions of the straight portion 42a of the cylindrical body 42, and an outer peripheral wall that rises rearward extends over the entire periphery of the outer periphery. The outer peripheral wall is inscribed in the cylindrical body 42 (inner cylinder 53) and appropriately joined by welding or the like. Hereinafter, the front separator 46 is disposed at the front portion of the cylindrical body 42, the rear separator 47 is disposed at the rear portion of the cylindrical body 42, and the space ahead of the front separator 46 is defined as the first chamber 45 a, the rear side A space behind the separator 47 will be described as a second chamber 45b, and a space between both separators will be described as a third chamber 45c.

  The first chamber 45a communicates with the internal space of the front cap 43. The first chamber 45a and the second chamber 45b are a first series of pipes 48a penetrating the separators 46 and 47 on the left side in the cylindrical body 42. Communicate via The second chamber 45 b and the third chamber 45 c communicate with each other via a second communication pipe 48 b that penetrates the rear separator 47 on the right side in the cylindrical body 42. Further, the third chamber 45 c and the external space (atmosphere) behind the end cap 44 communicate with each other via a third communication pipe 48 c that penetrates the rear separator 47 and the end cap 44 in the center of the cylindrical body 42.

  Accordingly, the exhaust gas from the engine first flows into the first chamber 45a from the exhaust pipe 35 through the front cap 43, and then flows into the second chamber 45b via the first series pipe 48a, and further to the second communication. After flowing into the third chamber 45c through the pipe 48b, it is discharged out of the muffler body 41 through the third communication pipe 48c. As described above, the high-temperature and high-pressure exhaust gas introduced into the muffler body 41 is cooled and decompressed through the process of passing through the plurality of chambers 45a, 45b, and 45c, thereby effectively reducing the exhaust noise. The

Each of the communication pipes 48a, 48b, 48c is an upstream end portion of a cylindrical pipe disposed in parallel with the axis C (specifically, the front end portion and the second communication portion in the first series pipe 48a and the third communication pipe 48c). The rear end portion of the pipe 48b is formed in a funnel shape. The front end portion of the third communication pipe 48 c is a separate configuration for the convenience of manufacturing the muffler body 41.
An inner peripheral wall that rises forward is formed on the inner peripheral portion of the through hole for the communication pipe in each separator 46, 47, and the inner peripheral wall circumscribes the corresponding communication pipe and is joined by welding or the like. Is done. A reinforcing bead is appropriately formed on the right side portion of the front separator 46.

  Further, an inner peripheral wall that rises rearward is formed on the inner peripheral portion of the through hole for the third communication pipe 48 c in the end plate 57 and the guide plate 64 of the end cap 44, The peripheral wall circumscribes the inner peripheral wall of the guide plate 64, and the inner peripheral wall of the guide plate 64 circumscribes the third communication pipe 48c and is joined over the entire circumference by welding or the like. The inner peripheral wall of the guide plate 64 rises gently so as to form a guide surface when the third communication pipe 48c is inserted into the through hole.

  The rear end portion of the third communication pipe 48 c is a tail pipe 48 d that protrudes rearward from the end cap 44 and forms an exhaust outlet from the muffler body 41. A peripheral portion of the tail pipe 48d is covered with a muffler end cover 58 attached to a rear end portion of the muffler main body 41. The muffler end cover 58 is fixed to the rear stay 59 provided on the end cap 44 with a bolt or the like.

  A punching portion 49a having a large number of small-diameter holes is formed in a portion of the third communication pipe 48c located in the second chamber 45b and immediately after the end cap 44. A diffuser pipe 49b is attached to cover the gap. The front and rear end portions of the diffuser pipe 49b are formed so as to smoothly reduce the diameter, and the front and rear end portions are circumscribed to the third communication pipe 48c and appropriately joined by welding or the like. At this time, part of the exhaust noise of the exhaust gas passing through the third communication pipe 48c is obtained by forming the glass wool filling layer 49A by inserting the glass wool G between the third communication pipe 48c and the diffuser pipe 49b. Is absorbed.

  Here, the outer cylinder 51 is configured as a single member across the cylinder body 42, whereas the intermediate cylinder 52 and the inner cylinder 53 have a boundary portion between the straight portion 42a and the taper portion 42b of the cylinder body 42. In FIG. Hereinafter, the portion on the straight portion 42a side in the intermediate tube 52 and the inner tube 53 is described as the front intermediate tube 52a and the front inner tube 53a, and the portion on the taper portion 42b side is described as the rear intermediate tube 52b and the rear inner tube 53b. The front end of the inner cylinder 53 a is supported by the intermediate cylinder 52 via the first guide plate 61, and the vicinity of the rear end is supported by the intermediate cylinder 52 via the second guide plate 62. On the other hand, the front inner end of the rear inner cylinder 53 is supported by the intermediate cylinder 52 via the third guide plate 63, and the rear end thereof is supported by the intermediate cylinder 52 via the guide plate (hereinafter referred to as the fourth guide plate) 64. 52.

The first guide plate 61 has an annular shape, and its rear portion is formed to have a stepped diameter with respect to the front portion, while the rear portion is inscribed in the intermediate cylinder 52 and appropriately joined by welding or the like, The front portion is supported in close contact with the intermediate cylinder 52 from the inside via a mesh-like spacer S joined to the outer periphery thereof.
Similarly, the second guide plate 62 also has an annular shape, and its front part is formed to have a stepped diameter with respect to the rear part. The front part circumscribes the inner cylinder 53 and is appropriately welded or the like. In addition to being joined, the rear part is inscribed in the intermediate cylinder 52 and joined appropriately by welding or the like.

Similarly, the third guide plate 63 has an annular shape, and its rear part is formed to have a stepped diameter with respect to the front part. The rear part is inscribed in the inner cylinder 53 and appropriately joined by welding or the like. The front part is inscribed in the intermediate cylinder 52 and is appropriately joined by welding or the like.
The fourth guide plate 64 is formed such that the front portion of the outer peripheral wall thereof is reduced in a stepped shape with respect to the rear portion, and the front portion is inscribed in the inner cylinder 53 and appropriately joined by welding or the like. The rear part is inscribed in the intermediate cylinder 52 and is appropriately joined by welding or the like.

The front portion of the third guide plate 63 extends forward from the front end of the rear intermediate tube 52, and the front portion is fitted in and inscribed in the rear end portion of the front intermediate tube 52, The butted end portions of both intermediate cylinders 52 together with the third guide plate 63 are integrally joined over the entire circumference by welding or the like. The weld bead at the part is indicated by reference sign Z in FIGS.
As described above, the intermediate cylinder 52 and the inner cylinder 53 are divided into the straight portion 42a side and the taper portion 42b side because the parts are attached to the taper portion 42b from the reduced side (rear side) or the axis C This is for avoiding the work of attaching components from the front side of the cylindrical body 42 in the tapered portion 42b which is the rear part of the cylindrical body 42 extending in the direction along the line. Here, when the intermediate | middle cylinder 52 and the inner cylinder 53 are assembled | assembled integrally, the glass wool filling layer 55A is comprised by interposing glass wool G between these.

Annular front and rear spacers 65 and 66 are disposed at the front and rear ends of the intermediate cylinder 52, and the outer cylinder 51 is supported by the intermediate cylinder 52 through the spacers 65 and 66.
The front spacer 65 is formed with a folded portion that rises from the rear end portion of the base portion that circumscribes the intermediate cylinder 52 toward the outer peripheral side and then folds forward. The folded portion is inscribed in the outer cylinder 51. Similarly, the rear spacer is formed with a folded portion that rises from the front end portion of the base portion circumscribing the intermediate cylinder 52 toward the outer peripheral side and then folds back toward the rear. The folded portion is inscribed in the outer cylinder 51.

The intermediate cylinder 52 and the base portions of the spacers 65 and 66 are joined over the entire circumference by brazing, for example, and the outer cylinder 51 and the folded portions of the spacers 65 and 66 are similarly joined by brazing, for example. By joining over the entire circumference, the outer peripheral space portion 54 formed between the outer cylinder 51 and the intermediate cylinder 52 is sealed.
Here, when performing the brazing, first, the outer cylinder 51, the intermediate cylinder 52, and the spacers 65, 66 are temporarily assembled with a brazing material interposed therebetween, and this assembly Is put into a vacuum brazing furnace maintained at about 10 ⁻³ Pa, for example, so that the outer cylinder 51, the intermediate cylinder 52, and the spacers 65 and 66 are brazed by heat treatment in the furnace atmosphere. At the same time, evacuation of the outer space 54 is performed.

  As shown in FIGS. 1 and 4, the muffler device 40 is disposed in the rear cowl 28 and directly below the pillion seat 20. A tail lamp 71 located above the rear end of the muffler device 40 is disposed at the rear end of the rear cowl 28. From the rear part of the seat frame 9, a pair of fender stays 72 positioned on both sides of the muffler device 40 extend obliquely downward and rearward, and the lower end part of the fender stay 72 supports the upper end part of the rear fender 73 and both sides thereof. The left and right rear turn signals 74 are supported on the left and right sides. In addition, a license lamp 75 positioned below the rear end of the muffler device 40 is disposed above the rear fender 73, and the license plate 75 illuminates the license plate 76 attached to the rear rear side of the rear fender 73. A rear reflector 77 is attached to the rear surface of the license lamp 75 housing.

  A bulging portion 78 is formed on both sides of the rear cowl 28 so as to project to the left and right. The air introduced from the air guide port 79 passes through the periphery of the muffler device 40 in the rear cowl 28 and is then discharged rearward from the rear end of the rear cowl 28. Therefore, when the motorcycle 1 travels, the muffler device 40 is satisfactorily cooled by the travel wind introduced from the air guide port 79.

  As described above, the muffler device 40 in the above embodiment is formed by forming the chambers 45a, 45b, 45c as the muffler chamber in the cylinder body 42, and the cylinder body 42 overlaps inside and outside. The outer cylinder 51, the intermediate cylinder 52, and the inner cylinder 53 are provided, and two layers of space portions 54, 55 are formed using the gaps between the tubes 51, 52, 53. , 55 is a vacuum layer 54A, and the other is a glass wool filled layer 55A.

According to this configuration, it is possible to improve the noise reduction and heat insulation performance by suppressing the exhaust noise and heat propagation by the two layers of the vacuum layer 54A and the glass wool filled layer 55A. The front and rear end portions do not need to be divided, and the structure can be simplified.
Moreover, since the adjustment range of the exhaust sound quality can be widened by giving the vacuum layer 54A and the glass wool filled layer 55A different sound-reducing characteristics, the muffler device 40 and consequently the merchandise of the motorcycle 1 can be improved. Can do.

  Further, in the muffler device 40, the vacuum layer 54A is arranged on the outer peripheral side of the glass wool filled layer 55A, so that the propagation of exhaust heat itself on the outer peripheral side of the cylindrical body 42 is cut off and the temperature on the outer peripheral side is reduced. Since it is possible to effectively suppress the rise, it is necessary to provide a separate heat insulating means (such as a heat guard) even when the muffler device 40 is disposed below the pillion seat 20 as in the motorcycle 1. In addition, the muffler device 40 can be reduced in size and weight, and the degree of freedom in designing the vehicle body can be improved.

  At this time, even if the connecting stay 56 to the seat frame 9 is directly attached to the outer cylinder 51 of the cylindrical body 42, the connecting stay 56 can be prevented from becoming hot, and the same effect as described above can be obtained. be able to.

  Furthermore, in the muffler device 40, the vacuum layer 54A is disposed on the outer peripheral side of the cylindrical body 42, and the outer cylinder 51 that forms the vacuum layer 54A is formed as a single member. Since the seam of the outer cylinder 51 does not appear on the outer surface, and the airtightness of the vacuum layer 54A can be easily secured, the appearance can be improved, the merchantability of the muffler device 40 and thus the motorcycle 1 can be improved, and the airtightness can be improved. It is easy to secure the manufacturing process and the number of manufacturing steps can be reduced.

Here, the muffler device 40 is applied to the motorcycle 1, and in other words, the muffler device 40 has its outer surface exposed under the pillion seat 20 of the motorcycle 1, in other words. By disposing the heat insulation cover as it is without providing a heat insulation cover or the like, for example, the vehicle body width of the motorcycle 1 is narrower than that when the muffler device 40 is disposed on the side of the vehicle body, and the heat insulation is provided by the vacuum layer 54A and the glass wool filling layer 55A. Propagation of exhaust sound to the pillion seat 20 can be suppressed without using a cover or the like.
That is, it is possible to provide a vehicle body structure in which the temperature of the pillion seat 20 is suppressed while narrowing the vehicle body width of the motorcycle 1, and it is possible to reduce cost and weight by eliminating the need for a heat insulating cover or the like.

The present invention is not limited to the above-described embodiment. For example, the cylindrical body 42 has a quadruple or more cylindrical member, and a triple or more space portion is formed in the cylindrical body 42. It may be a configuration. At this time, a plurality of vacuum layers 54A and glass wool filled layers 55A may be formed. Conversely, the cylinder 42 may have a double cylinder member, and the space formed in the cylinder 42 may be a vacuum layer 54A.
Further, felt or foam material may be used as a sound-absorbing heat insulating material instead of glass wool G.
Further, these supporting members can be directly attached to the outer cylinder 51 so that the muffler device 40 supports the lighting device such as the tail lamp 71 and the rear turn signal 74 and the license plate 76.
Furthermore, it goes without saying that the intermediate cylinder 52 and the inner cylinder 53 are preferably composed of a single member in the same manner as the outer cylinder 51.
And the structure in the said Example is an example, and it cannot be overemphasized that a various change is possible in the range which does not deviate from the summary of invention .

1 is a side view of a motorcycle according to an embodiment of the present invention. It is side explanatory drawing of the muffler apparatus of the said motorcycle. It is upper surface explanatory drawing of the said muffler apparatus. It is a rear view of the muffler device.

Explanation of symbols

20 Pillion sheet (sheet)
40 Muffler device (silencer for internal combustion engine)
42 cylinder 45a first chamber (silence room)
45b Second chamber (silence room)
45c Third chamber (silence room)
51 Outer cylinder (cylinder member)
52 Intermediate cylinder (cylinder member)
53 Inner cylinder (cylinder member)
54 Outer peripheral side space (space)
55 Inner circumference space (space)
54A Vacuum layer 55A Glass wool packing layer (sound absorbing heat insulating material packing layer)
56 Connection stay (connection member)

Claims (3)

In a silencer for an internal combustion engine of a motorcycle having a silencer chamber formed in a cylinder, the cylinder has at least a triple cylinder member inside and outside thereof, and at least using a gap between the cylinder members Two space portions are formed, and at least one of these space portions is a vacuum layer, and at least one other is a sound absorbing heat insulating material filling layer ,
Arranging the vacuum layer on the outer peripheral side than the sound-absorbing heat insulating material filling layer,
A silencer for an internal combustion engine of a motorcycle, wherein a connecting member to a seat frame is directly attached to a cylindrical member on an outer peripheral side of the cylindrical body . Disposing said vacuum layer on the outer peripheral side of the cylindrical body, and the vacuum layer for an internal combustion engine muffler of the motorcycle according to claim 1, characterized in that the tubular member forming the a single member. The muffler for an internal combustion engine of a motorcycle according to claim 1 or 2, wherein the muffler is disposed directly under the seat.

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