JP2015229952A - Muffler structure of motor cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a muffler structure of a motor cycle, which allows inner surface coating in a muffler body to be efficiently performed without causing increase of exhaust sound and deterioration of exhaust sound tone quality.SOLUTION: A muffler structure of a motor cycle comprises a muffler body 31 of a double wall structure with an annulus space 37 formed between an outer tube 35 and an inner tube 36, partition walls 43, 44 dividing the inside of the inner tube 36 of the muffler body 31 into plural expansion chambers 40, 41, 42, and end walls 45, 47 sectioning the front and rear of the muffler body 31. In a muffler 30 of the motor cycle, the inner tube 36 around the partition walls 43, 44 and the end walls 45, 47 of the muffler body 31 is formed with plural communication holes 60, 63, 70a, 72a for providing communication between the expansion chambers 40, 41, 42 and the annulus space 37.

Description

  The present invention relates to a muffler structure of a motorcycle.

  In motorcycles, the engine and engine exhaust system are exposed to the outside, so in the engine exhaust system of motorcycles where the appearance is important, the muffler connected to the exhaust pipe is plated to improve the aesthetics. ing.

  The muffler of a motorcycle uses an iron-based material that can be easily plated. However, the iron-based material muffler easily rusts the inner cylinder, and water containing rust comes out from the muffler drain hole, and the hole exit There is a problem that the surroundings are soiled or traces remain, for example, the stand is stained.

  As a countermeasure against this dirt, Japanese Patent Application Laid-Open No. 2003-259542 describes a technique for applying a rust prevention treatment to a muffler body of a motorcycle using a rust prevention paint on the inner surface of the muffler body. However, since the muffler is silenced, the inside of the muffler body is divided into a plurality of expansion chambers and has a complicated internal structure. For this reason, a special inner surface coating facility is required for the rust prevention treatment in the muffler.

  In the muffler structure of a motorcycle, in the inner surface coating using a rust preventive paint in the muffler, the rust preventive coating liquid is injected into the muffler body. The anti-corrosion coating liquid is discharged after coating, and a paint drain passage is required to remove the coating liquid from the muffler body.

  On the other hand, since the rust preventive coating liquid has a higher viscosity than the plating liquid, the coating liquid having a large viscosity cannot be sufficiently removed from the plating liquid drain hole. For this reason, as shown in FIG. 9, in the conventional muffler, the muffler body 1 has a double cylinder structure from the outer cylinder 2 and the inner cylinder 3, and the inside of the inner cylinder 3 is partitioned into a plurality of expansion chambers 4a, 4b, 4c. The diameter of the plating solution drain hole 6 of the baffle plate 5 is increased, or a paint removal notch 7 is provided to form a paint removal passage in the inner cylinder 3 of the muffler. Further, between the outer cylinder 2 and the inner cylinder 3 of the muffler, glass wool or the like is filled to form a soundproof structure.

JP-A-62-91614 Japanese Patent Laid-Open No. 11-247647

  In the conventional motorcycle muffler structure, the plating solution drainage hole is expanded to a large-diameter hole (for example, 10 mmφ) to serve as a paint removal passage, and the baffle plate 5 is provided with a paint removal notch 7 to provide a paint removal passage. Therefore, leakage due to a shortcut occurs in a part of the exhaust, and the exhaust noise increases and the exhaust sound quality deteriorates. For this reason, it has been difficult to obtain a high-quality, soft timbre exhaust sound.

  Furthermore, it is difficult for the antirust coating liquid to flow into and out of the annulus space 9 between the outer cylinder 2 and the inner cylinder 3, and it is difficult to discharge the coating liquid especially when the annulus space 9 is filled with glass wool or the like. there were.

  Further, in the muffler structure for motorcycles described in Patent Documents 1 and 2, exhaust gas that has flowed into the first-stage expansion chamber on the inflow side of the muffler is guided to the expansion chamber on the downstream side through the communication pipe. Since the communication pipe is open at the inlet end and a trumpet pipe is provided, exhaust noise due to exhaust pulsation passing through the communication pipe from the inflow side expansion chamber is large, and part of the exhaust is from the paint removal notch Since shortcuts (leakage) occur, exhaust noise increases and exhaust sound quality deteriorates, causing problems such as noise regulation and exhaust sound quality deterioration.

  Recently, noise regulations and exhaust sound quality are becoming a problem not only in developed countries but also in developing countries, and there is no need to increase exhaust noise noise or impair exhaust sound quality. There is a need for a muffler structure for a motorcycle that can efficiently coat the inner surface of the muffler without using the existing general inner surface coating equipment.

  The present invention has been made in consideration of the above-described circumstances, and has a muffler structure for a motorcycle that can efficiently perform the inner surface coating in the muffler body without causing an increase in exhaust noise or a decrease in exhaust sound quality. The purpose is to provide.

  Another object of the present invention is to provide a muffler structure for a motorcycle capable of efficiently and effectively applying the inner surface of the muffler body using a general inner surface coating facility.

  A muffler structure for a motorcycle according to the present invention includes a muffler body having a double wall structure in which an annulus space is formed between an outer cylinder and an inner cylinder, and an inner cylinder of the muffler body. In a muffler structure of a motorcycle having a partition wall that partitions the expansion chamber into a plurality of expansion chambers and an end wall that divides the front and rear of the muffler body, and the expansion chamber and the annulus are disposed in an inner cylinder around the partition wall and the end wall. A plurality of communication holes communicating with the space are provided.

  In the present invention, it is possible to efficiently coat the inner surface of the muffler body without causing an increase in exhaust sound or a decrease in exhaust sound quality. The inner surface of the muffler body can be efficiently and effectively performed using a general existing inner surface coating facility.

The whole external view which looked at the motorcycle provided with the muffler structure which concerns on this invention from the right side. The longitudinal cross-sectional view of the muffler body which shows embodiment of the muffler structure of a motorcycle. Sectional drawing which follows the AA line of FIG. Sectional drawing which follows the BB line of FIG. The rear view which follows the CC line of FIG. Sectional drawing which shows the inflow side edge part of the inner cylinder of a muffler body. The longitudinal cross-sectional view of the inflow tube provided in the inflow side end wall of the muffler body. The fragmentary sectional view in a muffler body which shows the communication structure of an annulus space and an expansion chamber. The fragmentary sectional view which shows the muffler body of the conventional muffler.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings.

  The embodiment of the present invention relates to a muffler structure of a motorcycle, and FIG. 1 is an overall external view of the motorcycle having the muffler structure as viewed from the right side. In the motorcycle 10, the front side of the vehicle is indicated by a symbol Fw, and the rear side of the vehicle is indicated by a symbol Rw.

  The motorcycle 10 includes a body frame 11 extending in the vehicle front-rear direction. The vehicle body frame 11 constitutes a main frame constituting a front frame of the front half of the vehicle and a rear frame of the rear half of the vehicle, and has a seat rail extending rearward and upward from the rear end of the main frame toward the rear of the vehicle. An engine (in this embodiment, a parallel 2-cylinder 4-cycle engine) 12 is mounted on the main frame. A fuel tank 13 is supported by the vehicle body frame 11 above the engine 12, and a seat 14 is provided behind the fuel tank 13. The seat 14 is, for example, a tandem type and is installed on the seat rail of the vehicle body frame 11.

  A head pipe 15 is provided at the front upper end of the vehicle body frame 11, and a front fork 16 is provided on the head pipe 15 via a steering mechanism so as to be steerable left and right. A front wheel 18 is rotatably supported at the lower end of the front fork 16. A swing arm 19 is attached to the rear portion of the main frame of the vehicle body frame 11 so as to be swingable up and down around the pivot shaft, and a rear wheel 20 is provided at the rear end portion of the swing arm 19. The rear wheels 20 are driven by the rear wheels by transmitting the power of the engine 12 through a known power transmission mechanism.

  The engine 12 has a cylinder assembly 23 extending obliquely forward and upward at the front upper part of the crankcase 22 constituting the engine case. The cylinder assembly 23 is provided with an intake port connected to the engine intake system 25 on the rear side of the cylinder head 24 and an exhaust port connected to the engine exhaust system 26 on the front side of the cylinder head 24.

  The engine exhaust system 26 has an exhaust pipe 28 whose base end is connected to the exhaust port of the cylinder head 24. Each exhaust pipe 28 extends from the front lower side of the cylinder head 24 to the lower side of the crankcase 22 (of the engine case) and extends to the vehicle rear side Rw, and a muffler 30 is connected to the rear end. The muffler 30 is configured by combining a cylindrical muffler body 31, a head cover 32 on the muffler head side, and a tail cover 33 on the muffler tail side.

  As shown in FIG. 2, the muffler 30 has a muffler body 31 that forms a cylindrical main body casing. The muffler body 31 is composed of an outer cylinder 35 of a cylindrical outer casing and an inner cylinder 36 of an inner casing. A cylinder having a cylinder (double wall) structure is formed. In the muffler body 31, an annulus (annular) space 37 is formed between a concentric outer cylinder 35 and an inner cylinder 36, and the annulus space 37 is filled with a metal mesh, glass wool, or stainless wool as necessary, and is soundproofed. Configured to structure. In the present embodiment, the annulus space 37 is filled with a metal mesh or is not filled with a filler, and is left as an annular space as a space, and the annulus space 37 is configured as a paint passage as described later. Also serves as a soundproof structure.

  The cylinder body of the muffler body 31 is formed in a cylindrical shape that gradually expands from the exhaust gas inflow side to the exhaust side from the engine 12, and has a plurality of expansion chambers (three expansion chambers in this embodiment) in the cylinder body. Partition walls 43 and 44 partitioned into 40, 41 and 42 are formed as baffle plates. End walls 45 and 47 are provided on the exhaust gas inflow side and the exhaust side of the muffler body 31 so that both ends of the muffler body 31 are closed.

  The inner cylinder 36 of the muffler body 31 is inflated at the inflow side end portion, fitted into the outer cylinder 35, and integrally joined. Further, the end wall 45 is inserted into and fitted into the inflow side end portion (expansion step portion) of the inner cylinder 36. Therefore, the outer cylinder 35, the inner cylinder 36 and the end wall 45 are fitted to each other at the inflow side end of the muffler body 31, and are integrally welded by welding means such as an iron filler rod. An inflow pipe 46 is inserted into the inflow side end wall 45, and exhaust gas flows into the first-stage expansion chamber 40 on the inflow side through the inflow pipe 46.

  Further, the outer cylinder 35 of the muffler body 31 is sandwiched so that the discharge side end portion is folded back to the inner peripheral side and the sleeve-like outer peripheral flange 48 of the discharge side end wall 47 is wrapped around the bent portion. The discharge side end wall 47 constitutes a rear end baffle plate and closes the rear end portion of the muffler body 31. Further, a dish-like step portion 49 that protrudes to the front end side of the muffler body 31 is formed on the inner peripheral side of the outer peripheral flange 48 of the discharge side end wall 47. The dish-like step portion 49 is inserted into the discharge side end portion of the inner cylinder 36, fitted and integrated by welding or the like, and the rear end of the inner cylinder 36 is closed.

  Further, the partition walls 43 and 44 for partitioning the inner cylinder 36 of the muffler body 31 into a plurality of expansion chambers 40, 41 and 42 are, in the present embodiment, the first partition wall 43 on the inflow side and the second partition wall 44 on the discharge side. It consists of. In the first partition wall 43, the reinforcing ribs 50 extending radially from the center portion of the baffle plate are formed in a concave shape or a convex shape, and the plate strength is reinforced. A sleeve-shaped outer peripheral flange 51 is integrally formed on the outer peripheral portion of the first partition wall 43. The outer peripheral flange 51 is inserted and fitted into the inner peripheral wall of the inner cylinder 36 from the opening side of the discharge side end portion and integrated. The first partition wall 43 is integrally joined to the inner peripheral wall of the inner cylinder 36 by press-fitting or welding. The communication hole 60 is, for example, a hole of 8 mmφ to 10 mmφ for coating liquid, and the intermediate expansion chamber 41 is communicated with the annulus space 36 through the communication hole 60. The outer peripheral flange 51 side of the partition wall 43 may be formed with a U-shaped or rectangular cutout instead of the communication hole.

  Further, the communication hole 60 is not necessarily formed through the overlapping portion of the outer peripheral flange 51 of the first partition wall 43 and the inner peripheral wall of the inner tube 36, and the inner tube 36 near the vicinity of the first partition wall 43. It may be formed. However, the communication hole 60 provided in the inner cylinder 36 around the partition wall portion is installed at at least one position where the muffler body 31 faces the vehicle body width direction inner side and the vehicle body lower side when the muffler 30 is attached to the vehicle body of the motorcycle 10. May be. In the present embodiment, in the overlapping portion of the inner cylinder 36 of the muffler body 31 and the outer peripheral flange 51 of the first partition wall 43, the communication hole 60 is formed at both the inner side in the vehicle body width direction and the lower side of the vehicle body. Show.

  In addition, the second partition wall 44 is also formed with a sleeve-shaped outer peripheral flange 52 on the outer peripheral portion, and the outer peripheral flange 52 is inserted into the inner peripheral wall of the inner cylinder 36 from the opening of the discharge side end portion and integrated. Similarly to the one partition wall 43, they are joined together. Similar to the communication holes 60 and 63 in the periphery of the first partition wall 43, a communication hole 63 is also provided in the overlapping portion of the outer peripheral flange 52 of the second partition wall 44 and the inner peripheral wall of the inner cylinder 36. The communication holes 60 and 63 are formed in a plurality of places, for example, two places, in portions where the outer peripheral flanges 51 and 52 of the partition walls 43 and 44 and the inner peripheral wall of the inner cylinder 36 overlap.

  The first partition wall 43 and the second partition wall 44 are formed with through holes for insertion support of the communication pipe 55. For example, the communication pipe 55 is inserted from the through hole of the second partition wall 44 through the through hole of the first partition wall 43 and fixed integrally by welding or the like. The communication pipe 55 protrudes from the through hole of the first partition wall 43 into the first-stage expansion chamber 40 on the inflow side, and a hole region 57 in which a large number of punching holes 56 are formed in the protruding portion. The punching hole 56 is formed with a hole of several mmφ, for example, about 3 mmφ or 4 mmφ in this embodiment. The inflow end of the communication pipe 55 is fixed with an end plug 58. A hole having the same diameter as the punching hole 56 is formed in the end plug 58, and the discharge side of the communication pipe 55 opens into the expansion chamber 42 in the next stage.

  The communication pipe 55 is formed into a tubular shape by extrusion molding or pultrusion molding. However, in this embodiment, as shown in FIGS. 2 and 3, the plate member is rolled and formed into a tubular shape, and the butted surface or the overlapped surface is welded by TIG welding or the like, and is integrally formed into a tubular shape. Before the plate member is formed into a tubular shape, punching is performed in which a punching hole 56 is formed in the hole region 57.

  Further, as shown in FIGS. 2 and 4, three through holes are formed in the second partition wall 44. The through hole at the center of the second partition wall 44 is a hole for supporting the insertion of the tail pipe 61. The hole for supporting the insertion of the communication pipe 55 is formed below the central through hole, and the baffle pipe is formed on the opposite upper side. 62 insertion support holes are formed. The communication pipe 55 and the baffle pipe 62 are inserted into the through-hole from the second expansion chamber 42 on the discharge side and fixedly supported by welding or the like, while the tail pipe 61 is inserted from the inflow side expansion chamber 40 to the discharge side end. The wall 47 is supported through a central through hole. The rear end of the tail pipe 61 projects from the discharge-side partition wall 47 and ends, and the projecting portion is covered with the tail cover 33.

  The second partition wall 44 is formed with a sleeve-like outer peripheral flange 52 at the outer peripheral portion, and the outer peripheral flange 52 is press-fitted or welded to the inner peripheral wall of the inner cylinder 36 (of the muffler body 31) from the opening of the discharge side end portion. Integrated. A plurality of communication holes 63 are formed in a portion where the outer peripheral flange 52 and the inner cylinder 36 of the second partition wall 44 are overlapped, and in this embodiment, two holes are formed by drilling. The communication hole 63 is a hole of, for example, 8 mmφ to 10 mmφ for draining the coating liquid, and communicates the second stage expansion chamber 42 and the annulus space 37. The outer peripheral flange 52 side may be a U-shaped or rectangular cutout instead of the communication hole.

  Furthermore, the discharge side end wall 47 of the muffler body 31 is configured as shown in FIGS. A through hole for insertion support of the tail pipe 61 is formed at the center of the end wall 47. A plurality of mounting brackets 65 for attaching the tail cover 33 are attached to the rear end face of the end wall 47, and three in the present embodiment are fixed by welding or the like at equal intervals in the circumferential direction. As shown in FIG. 6, a screw hole nut 66 is fixed to the attachment bracket 65, and the tail cover 33 is attached via the attachment bracket 65. The tail cover 33 covers the protruding portion of the tail pipe 61 to improve the appearance of the muffler 30.

  In FIG. 5, reference numeral 67 is a mounting bracket for mounting the muffler 30 to the rear frame side of the vehicle body frame 11, and reference numeral 68 is a hole of 4 mmφ for removing the plating solution.

  3 and 4, the first and second partition walls 43 and 44 are also provided with holes of, for example, 6 mmφ for removing the plating solution as indicated by reference numeral 69, respectively. The hole 68 for the plating solution is closed by plug welding after the muffler 30 is treated with the plating solution.

  Further, as shown in FIG. 6, the inner cylinder 36 of the muffler 30 has an inflow side end portion that is expanded to form a stepped portion 36a, and a plurality of (in this embodiment) the outer periphery of the inflow side end portion 36a. 4) notches 70 are formed at equal intervals in the circumferential direction. The notch 70 has a groove width of several millimeters and a width direction length of several tens of millimeters (in this embodiment, the groove width is 4 mm and the axial direction length is 17 mm), and the inflow side step portion 36a of the inner cylinder 36 is connected to the outer cylinder 35. When fitted and overlapped, a U-shaped, oval or rectangular through hole 70a is formed as a communication hole for communicating the inflow side expansion chamber 40 to the annulus space 37 in the overlapped portion.

  Furthermore, as shown in FIG. 7, the inflow pipe 46 to the inflow side expansion chamber 40 of the muffler body 31 is formed with a plurality of oval holes and elliptical through holes 71 (three in this embodiment). The The through hole 71 opens from the end surface on the expansion chamber 40 side of the inflow side end wall 45 into the inflow side (first stage) expansion chamber 40 and functions as a paint liquid draining hole. Has an opening larger than the hole.

  On the other hand, the first partition wall 43 and the second partition wall 44 in the muffler body 31 include overlapping portions of the outer peripheral flanges 51 and 52 and the inner peripheral wall of the inner cylinder 36 as shown in FIGS. The communication holes 60 and 63 are formed in the first and second holes. The communication holes 60 and 63 are formed as shown in FIG. 8, and the expansion chambers 41 and 42 (second stage and third stage) communicate with the annulus space 37. The diameters of the communication holes 60 and 63 are formed to be larger than the hole for the plating solution (8 mmφ to 10 mmφ in this embodiment) in consideration of the viscosity of the coating solution.

  Further, as shown in FIG. 2, the inner cylinder 36 of the muffler body 31 is formed with a plurality of cutouts 72 (four in this embodiment) at equal intervals in the circumferential direction at the discharge side end. The notch 72 is formed in a U shape or a rectangular shape and extends in the axial direction and terminates. When the discharge side end portion of the inner cylinder 36 is fitted and closed to the end wall 47 of the rear end baffle plate, the expansion chamber 42 is connected to the discharge side end portion of the inner cylinder 36 via the through hole (communication hole) 72a. 37 is communicated.

  When the muffler body 31 of the muffler 30 is assembled, an annulus (annular) space 37 is formed between the outer cylinder 35 of the outer casing and the inner cylinder 36 of the inner cylinder casing. The wall 45 is closed and closed with a metal filler rod such as iron. Further, the discharge side end portion of the muffler body 31 is closed and closed together with the end wall 47 which is a discharge side baffle plate by a filler rod. The annulus space 37 formed between the outer cylinder 35 and the inner cylinder 36 of the muffler body 31 is closed and closed at the inflow side end and the outflow side end, and is blocked from the outside air.

  On the other hand, an annulus space 37 between the outer cylinder 35 and the inner cylinder 36 is provided with each expansion chamber 40, 41, 42 in the inner cylinder 36 and a through hole (communication hole) 70a in the inflow side step portion 36a of the inner cylinder 36. The first and second partition walls 43, 44 communicate with each other through the communication holes 60, 63 in the outer flanges 51, 52 (regions) and through holes (communication holes) 72a at the end on the outflow side of the inner cylinder 36. Is done. Each of the plurality of communication holes (through holes 36a, 72a, communication holes 60, 63) is formed in a size that allows a coating liquid having a high viscosity to flow smoothly, and has a diameter larger than that of the plating liquid holes 68, 69 having a low viscosity. Is big.

  Therefore, the components of the plated body 31 (the outer cylinder 35 and the inner cylinder 36, the inflow and discharge end walls 45 and 47, the first and second partition walls 43 and 44, the communication pipe 55, the baffle pipe 62, the tail pipe) 61, etc.), the annulus space 37 between the double walls of the outer cylinder 35 and the inner cylinder 36 can constitute a coating (paint) liquid passage, as shown in FIGS.

[Painting inside the muffler]
In the inner surface coating of the muffler 30 using the anticorrosive coating liquid, an annulus space 37 having a double wall structure of the outer cylinder 35 and the inner cylinder 36 of the muffler body 31 is configured as a passage for the coating liquid, and a plurality of annulus spaces 37 are formed. These coating holes (through holes 70a, 72a and communication holes 60, 63) communicate with the respective expansion chambers 40, 41, 42, and the coating liquid can be circulated. The anticorrosive coating liquid that has flowed into the muffler body 31 can flow smoothly and freely as an annulus space 37 between the outer cylinder 35 and the inner cylinder 36, a coating liquid passage, and a coating liquid drainage passage. Painting with the coating liquid flowing into the muffler 30 can be easily performed by rotating the muffler body 31 around the central axis in the state of the coating liquid flowing. The coating liquid is discharged from the inflow side end 36a of the inner cylinder 36 and the outflow side end of the inner cylinder 36 through the expansion chamber from the U-shaped, oval, rectangular through holes 70a, 72a, etc. It is discharged to the outside through the through hole 71 of the inflow pipe 46.

  For this reason, it becomes easy for the anti-corrosion coating liquid to flow into and out of the muffler body 31, and the annulus space 37 between the outer cylinder 35 and the inner cylinder 36 serves as a coating liquid passage. Distribution is smooth. Since the coating liquid is easily removed from the muffler body 31, the inner surface of the muffler body 31 can be dipped in the existing general-purpose inner surface coating equipment without using a special dedicated coating equipment. it can. In addition, in the case of providing an inner surface dedicated interior coating facility such as rotating the muffler 30 around the longitudinal (center) axis for coating, the muffler 30 is sprayed by a small amount of coating liquid from the spray nozzle of the dedicated inner surface coating facility. Can be rotated and painted.

  In addition, with the muffler 30 attached to the motorcycle 10, the positions of the communication holes 60 and 63 formed in the first and second partition walls 43 and 44 which are baffle plates in the inner cylinder 36 (of the muffler body 31). Is formed at a position facing the inner side in the vehicle body width direction and the lower part of the vehicle body, and in a portion where the outer peripheral flanges 51 and 52 and the inner peripheral wall of the inner cylinder 36 overlap each other, even if a discoloration portion due to heat is generated in the muffler body 31. , It can be formed in an inconspicuous portion.

  The muffler 30 of the present embodiment can smoothly and reliably circulate the coating liquid in the annulus space 37 between the double wall of the outer cylinder 35 and the inner cylinder 36 of the muffler body 31, and can perform the inner surface coating. Since the coating liquid reliably travels to the annulus space 37 in the muffler body 31, coating failure can be prevented and rust-proof coating can be reliably applied.

  By the way, the annulus space 37 between the outer cylinder 35 and the inner cylinder 36 of the muffler body 31 constituting the muffler 30 is a portion that is least corroded. When the engine 12 is stopped and cooled after traveling, the muffler 30 is a portion where the outer cylinder 35 is likely to form dew and does not generate rust. However, in this embodiment, the annulus space 37 between the outer cylinder 35 and the inner cylinder 36 of the muffler body 31 can be used as a flow path for the coating liquid, and the coating liquid can be applied to the annulus space 37 for coating. It is possible to prevent poor coating.

  Moreover, the communication holes 60 and 63 with the annulus space 37 formed around the partition walls 43 and 44, which are baffle plates in the muffler body 31, are provided so that the hole positions are on the lower side (vehicle width direction) inside of the motorcycle. Thus, when the engine 12 is running at a high load, even if hot exhaust gas blows out from the communication holes 60 and 63 toward the outer cylinder 35 and changes color, the communication hole forming position is provided at a position where it is difficult to be exposed to the outside. Less adversely affects the appearance.

  Moreover, even if a special dedicated inner surface coating facility is not provided, the muffler 30 can be produced with a general thick inner surface coating facility, and the muffler 30 can be efficiently produced without increasing the cost. Can do.

[Muffler noise problem]
In the motorcycle 10, exhaust gas from the engine 12 is discharged to the engine exhaust system 26 and sent to the muffler 30. When passing through the expansion chambers 40, 41, and 42 having a multi-stage structure (three stages in this embodiment) in the muffler 30, pressure pulsations are sequentially smoothed by the muffler effect due to expansion, airflow noise is silenced, and exhaust noise is reduced. Exhausted from the tail pipe 61 to the outside.

  The muffler body 31 of the muffler 30 has multi-stage (three-stage in this embodiment) expansion chambers 40, 41, and 42 therein, and the expansion chambers 40, 41, and 42 are pipes 55, 62, and 61 (communication pipe 55, The baffle pipe 62 and the tail pipe 61) communicate with each other. In the first-stage expansion chamber 40 on the inflow side of the muffler body 31, the engine exhaust gas is sent directly from the inflow pipe 46, so the pressure pulsation of the exhaust gas is larger than the other expansion chambers 41 and 42, and the air flow noise (noise) is large. . In order to make the airflow sound due to the exhaust pressure from the first stage expansion chamber 40 a soft tone, the inlet side of the communication pipe 55 is closed with an end plug 58, while a hole region 57 is provided to provide a number of punching holes (3 mmφ in this embodiment). Alternatively, 4 mmφ) 56 is provided. By providing a large number of punching holes 56, the tone of the exhaust pressure is such that the exhaust sound quality is “pa, pat,...”, “Open” at the inlet end of the communication pipe 55 or the bell mouth shape. The exhaust sound quality is prevented from deteriorating so that the exhaust sound quality becomes a soft tone such as “Poor, Poor” or “Poor, Poor” instead of the sound of “bo, bo,.

  The cross-sectional area and volume of each expansion chamber 40, 41, 42, the diameter and length of the pipe are set so as to enhance the muffler effect by silencing and at the same time not increase the outlet loss. At the inlets of the pipes (baffle pipes and tail pipes) 62, 61 on the next stage side, airflow noise generated by the exhaust gas flow is reduced to some extent, so that the baffle pipe 62 and the tail pipe 61 are not provided with punching holes. The inlet resistance of the baffle pipe 62 and the tail pipe 61 is reduced while the outlet loss of the exhaust pressure is sucked without opening the opening or by providing a bell mouth to provide a punching hole.

  Further, the annular space 37 having a double tube (wall) structure composed of the outer tube 35 and the inner tube 36 is closed at both ends in the axial direction to form an expansion chamber, so that airflow noise does not leak to the outside. In addition, it is constructed in a soundproof structure by airflow sound silencing.

  The muffler 30 of the motorcycle 10 is exposed to the outside like the exhaust pipe 28 and is an important part in appearance, but discoloration and rust are likely to occur due to the heat of exhaust gas. In the muffler structure of the motorcycle 10 of the present embodiment, the inner surface coating including the annulus space 37 between the outer cylinder 35 and the inner cylinder 36 is performed in the muffler body 31 of the plating muffler 30 subjected to chrome plating, and corrosion is applied. Is suppressed.

  In addition, in the muffler structure of the motorcycle of the present invention, the example in which the inner surface coating is applied to the plating muffler has been described, but the muffler for heat-resistant coating is also developed to the same inner surface coating structure so as to enhance the rust prevention effect of the muffler. Also good. Moreover, in the muffler structure of a motorcycle, an iron-based material that can be downgraded can be used as the muffler material in addition to the aluminum-plated steel plate and the stainless steel plate by coating the muffler with the inner surface.

  Furthermore, this muffler structure is applied not only to motorcycles but also to vehicles of the type in which the muffler is exposed to the outside.

  As mentioned above, although embodiment of this invention was described, this embodiment is shown as an example and is not intending limiting the range of invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

10 motorcycle 11 body frame 12 engine 13 fuel tank 14 seat 15 head pipe 16 front fork 17 handle 18 front wheel 19 swing arm 20 rear wheel 22 crankcase (engine case)
23 Cylinder assembly 24 Cylinder head 25 Engine intake system 26 Engine exhaust system 28 Exhaust pipe 30 Muffler 31 Muffler body 32 Head cover 33 Tail cover 35 Outer cylinder (outer casing)
36 Inner cylinder (inner casing)
36a Inflow side step (inflow side end)
37 Annulus space 40, 41, 42 Expansion chamber 43, 44 Partition (baffle plate)
45 (inflow side) end wall 46 inflow pipe 47 (discharge side) end wall (rear end baffle plate)
48, 51, 52 Outer peripheral flange 49 Dish-shaped step portion 50 Reinforcement rib 55 Communication pipe 56 Punching hole 57 Hole region 58 End plug 60, 63 Communication hole 61 Tail pipe 62 Baffle pipe (communication pipe)
65 Mounting Bracket 66 Nut 67 Mounting Bracket 68, 69 Hole (Plating Solution (Removal) Hole)
70 Notch 70a Through hole (communication hole)
71 Through-hole 72 Notch 72a Through-hole (communication hole)

Claims (9)

A muffler body having a double wall structure in which an annulus space is formed between the outer cylinder and the inner cylinder, a partition wall that partitions the inner cylinder of the muffler body into a plurality of expansion chambers, and an end wall that partitions the front and rear of the muffler body In the muffler structure of a motorcycle equipped with
A muffler structure for a motorcycle, wherein a plurality of communication holes for communicating the expansion chamber and the annulus space are provided in an inner cylinder around the partition wall and the end wall. The communication hole provided in the inner cylinder around the partition wall is located at least one of the muffler body in the vehicle width direction and the vehicle body lower side when the muffler is attached to the motorcycle body. The muffler structure of a motorcycle. 3. The muffler structure for a motorcycle according to claim 2, wherein the communication hole provided in the inner cylinder around the partition wall is formed through an overlapping portion between an inner peripheral surface of the inner cylinder and an outer peripheral flange of the partition wall. The muffler structure for a motorcycle according to any one of claims 1 to 3, wherein a communication hole provided in an inner cylinder around the partition wall is located on one side of the partition wall and has a diameter of 8mmφ to 10mmφ. The muffler structure for a motorcycle according to claim 1 or 2, wherein a plurality of communication holes provided in an inner cylinder around the end wall are provided along a circumferential direction. The communication hole provided around the end wall is provided with a circumferential interval in the inflow side end portion and the discharge side end portion of the inner cylinder and extends in the longitudinal axis direction, or an oval shape, The muffler structure for a motorcycle according to claim 5, comprising a rectangular cutout. The muffler structure for a motorcycle according to claim 1 or 5, wherein an inflow pipe provided in an end wall of the muffler body is provided with a paint hole that also serves as a water drain hole. Both ends of the annulus space formed between the outer cylinder and the inner cylinder of the muffler body are closed, and this annulus space is connected to each expansion chamber in the inner cylinder of the muffler body and the plurality of communication holes. The muffler structure for a motorcycle according to claim 1 or 6, wherein the annulus space is formed with a passage for an anticorrosive paint liquid. The partition wall that partitions the inner cylinder of the muffler body into a plurality of expansion chambers is provided with a communication pipe that communicates the first-stage expansion chamber on the inflow side and the second-stage expansion chamber on the wake side, and the communication pipe 2. The motorcycle muffler structure according to claim 1, wherein an opening on the inlet side of the motorcycle is closed by an end plug, a hole region is formed on the inlet side of the communication pipe, and a number of punching holes are formed in the hole region.

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