JP2007032480A - Exhaust system for multi-cylinder engine for motorcycle - Google Patents

Abstract

A multi-cylinder engine for a motorcycle in which a downstream end of a throttle pipe connected to at least one downstream end of a plurality of exhaust pipes is inserted into at least one of a plurality of individual pipe parts provided in a merged exhaust pipe. In this exhaust system, the dimensional accuracy of the throttle pipe can be increased regardless of the exhaust pipe, and the design can be changed by the throttle pipe alone, thereby increasing the degree of design freedom.
A throttle pipe 41, which is a separate member from the exhaust pipes 22, 23, is fixed to the downstream end of at least one exhaust pipe 22.
[Selection] Figure 6

Description

  The present invention includes a plurality of exhaust pipes whose upstream ends are connected to an engine body of a multi-cylinder engine, a plurality of individual pipe portions that individually connect the downstream ends of the exhaust pipes, and a downstream end of each individual pipe portion. A throttle comprising a confluence exhaust pipe composed of a common confluence pipe section and an exhaust muffler connected to a downstream end of the confluence pipe section, and being connected to at least one downstream end section of each exhaust pipe The present invention relates to an exhaust device for a multi-cylinder engine for a motorcycle in which a downstream end of a pipe is inserted into at least one of the individual pipe portions.

A plurality of exhaust pipes extending from a multi-cylinder engine are connected in common to the merged exhaust pipe, and a throttle pipe connected to one downstream end of each exhaust pipe is inserted into the merged exhaust pipe. An exhaust device for a multi-cylinder engine for a motorcycle that improves the output characteristics in the low and medium speed ranges is known, for example, from Patent Document 1.
JP-A-62-99628

  In the above-mentioned conventional one, the throttle pipe is formed integrally with the exhaust pipe by processing so that the downstream end portion of one exhaust pipe is narrowed, and the throttle pipe inserted into the merged exhaust pipe is the junction pipe. It is welded and joined to the exhaust pipe.

  By the way, the length of the throttle pipe has a severe influence on the output characteristics of the engine, and the pipe length of the throttle pipe is required to have high dimensional accuracy, and the throttle pipe is easily designed according to the motion characteristics of the motorcycle. A high degree of design freedom is required to enable changes.

  However, since the throttle pipe is integrally formed with the exhaust pipe in the above-mentioned conventional type, it is difficult to improve the dimensional accuracy with the throttle pipe alone, and when trying to change the design of the throttle pipe, the entire exhaust pipe is side-designed. It is necessary to fix, design freedom is not high.

  The present invention has been made in view of such circumstances, and it is possible to increase the dimensional accuracy of the throttle pipe irrespective of the exhaust pipe and to increase the degree of design freedom by allowing the design change of the throttle pipe alone. An object is to provide an exhaust device for a multi-cylinder engine for a motorcycle.

  In order to achieve the above object, the invention according to claim 1 is a plurality of exhaust pipes whose upstream ends are connected to the engine body of a multi-cylinder engine, and a plurality of exhaust pipes individually connecting the downstream ends of the exhaust pipes. A merging exhaust pipe composed of a merging pipe part in which the downstream ends of the individual pipe parts and the individual pipe parts are connected in common; and an exhaust muffler connected to the downstream end of the merging pipe part, In an exhaust system for a multi-cylinder engine for a motorcycle, in which a downstream end of a throttle pipe connected to at least one downstream end is inserted into at least one of the individual pipes, the exhaust pipe is a separate member. The throttle pipe is fixed to a downstream end portion of at least one exhaust pipe.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, a sound absorbing means is provided in the merging exhaust pipe in the vicinity of the downstream end of the throttle pipe.

  According to a third aspect of the present invention, in addition to the configuration of the first or second aspect of the invention, the engine body having a pair of V-shaped banks has an upstream end connected thereto and a plurality of lengths different from each other. The upstream end of the throttle pipe is fixed to the downstream end of the shortest exhaust pipe among the exhaust pipes, and the downstream end of the throttle pipe is inserted into the shortest individual pipe section among the plurality of individual pipe sections and is the shortest. It is arrange | positioned rather than the downstream end of exhaust pipes other than the said exhaust pipe at the back side in alignment with the front-back direction of a motorcycle.

  In addition to the configuration of the invention described in claim 3, the invention according to claim 4 is characterized in that an upstream end is provided at an exhaust port provided on the opposite side surfaces of the banks disposed in the front-rear direction of the motorcycle. A downstream end of the exhaust pipe to be connected is disposed below the engine body and between the exhaust ports of both banks, and the merged exhaust pipe is connected to the downstream end of the exhaust pipes below the engine body, A catalyst is disposed in an exhaust passage downstream of the merged exhaust pipe.

  According to the first aspect of the present invention, the throttle pipe is a separate member from the plurality of exhaust pipes and is fixed to the downstream end portion of at least one exhaust pipe, so that the throttle pipe is independent of the exhaust pipe. The dimensional accuracy of the pipe can be increased, and the design change can be made possible by changing the design of the throttle pipe alone.

  According to the second aspect of the invention, since the throttle tube has a high degree of freedom in shape, it is possible to provide a sound absorbing means in the merged exhaust pipe in the vicinity of the downstream end of the throttle pipe. By appropriately determining the above, it is possible to obtain an excellent sound absorbing effect by the sound absorbing means.

  According to the third aspect of the present invention, the configuration and length of the exhaust pipe are particularly limited due to the arrangement space and layout associated with the multi-cylinder engine mounted on the motorcycle being a V-type multi-cylinder engine. However, the throttle pipe is fixed to the downstream end portion of the shortest exhaust pipe to improve the output characteristics in the middle and low speed ranges, and the output characteristics of the engine can be easily changed.

  Furthermore, according to the invention of claim 4, the length of the exhaust pipe from the pair of banks to the merged exhaust pipe is set as short as possible, the temperature difference of the exhaust gas merged in the merged exhaust pipe is reduced, and the combined exhaust pipe The purification performance by the downstream catalyst can be stabilized. In addition, the distance from each exhaust pipe to the catalyst can be secured, the temperature of the exhaust gas in contact with the catalyst can be made uniform, and the reduction in purification efficiency at the catalyst can be suppressed.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

  1 to 11 show an embodiment of the present invention, FIG. 1 is a side view of a motorcycle, FIG. 2 is a front view of an engine and an exhaust device viewed from the direction of arrow 2 in FIG. Is a plan view of a part of the exhaust device viewed from the direction of the arrow 4 in FIG. 3 while omitting the engine, and FIG. 5 is a view of the exhaust device in the direction of the arrow 5 in FIG. 6 is an enlarged sectional view taken along line 6-6 in FIG. 5, FIG. 7 is a sectional view taken along line 7-7 in FIG. 6, FIG. 8 is a sectional view taken along line 8-8 in FIG. 5 is an enlarged sectional view taken along line 9-9 in FIG. 5, FIG. 10 is a sectional view taken along line 10-10 in FIG. 5, and FIG. 11 is an output characteristic diagram of the engine.

  First, in FIG. 1, a front fork 16 that pivotally supports a front wheel WF is supported on the front end of a body frame 15 of the motorcycle so that it can be steered, and a rear wheel WR is pivotally supported at a rear portion of the body frame 15. The front portion of the swing arm 17 is supported so as to be swingable up and down. An engine main body 18 of a V-type multi-cylinder engine E is disposed between the front wheel WF and the rear wheel WR. The engine main body 18 is suspended on the vehicle body frame 15, and the power from the multi-cylinder engine E is partially Is transmitted to the rear wheel WR via a shaft drive type transmission mechanism (not shown) accommodated in the swing arm 17.

  2 and 3, the engine main body 18 has a pair of first and second banks BA and BB in the front-rear direction of the motorcycle and is configured in a two-cylinder V-shape. , BB, exhaust devices 21 are connected to exhaust ports 20A, 20B, one on each of the opposite side surfaces of cylinder heads 19A, 19B.

  The exhaust device 21 includes a pair of first and second exhaust pipes 22 and 23 whose upstream ends are connected to the exhaust ports 20A and 20B of the cylinder heads 19A and 19B in the engine body 18, and the first and second exhaust pipes 22 respectively. , 23 are connected to each other and a pair of first and second individual pipe parts 24a, 24b and a combined exhaust part 24c in which the downstream ends of both individual pipe parts 24a, 24b are connected in common. A pipe 24, a catalytic converter 25 connected to the downstream end of the merging pipe portion 24 c in the merging exhaust pipe 24, and an exhaust muffler 26 connected to the downstream end of the catalytic converter 25.

  Referring also to FIG. 4, the first exhaust pipe whose upstream end is connected to the exhaust port 20 </ b> A on the front side surface of the cylinder head 19 </ b> A in the first bank BA on the front side of both banks BA and BB included in the engine body 18. 22 hangs downward from the exhaust port 20A in front of the engine body 18 and further extends to the rear side on the lower right side of the engine body 18 with the motorcycle facing forward in the front-rear direction.

  The second exhaust pipe 23 whose upstream end is connected to the exhaust port 20B on the rear side of the cylinder head 19B in the second bank BB on the rear side of both banks BA and BB provided in the engine body 18 is a longitudinal direction of the motorcycle. It is bent so as to face the right side of the engine body 18 from the exhaust port 20 </ b> B while facing forward, and extends downward on the right side of the engine body 18, and then extends rearward below the engine body 18.

  Thus, the downstream ends of the first and second exhaust pipes 22 and 23 are disposed below the engine body 18 and between the exhaust ports 20A and 20B of the banks BA and BB. That is, as clearly shown in FIG. 3, in the side view, the downstream ends of the first and second exhaust pipes 22 and 23 are between the vertical lines LA and LB hanging downward from the centers of the opening ends of the exhaust ports 20A and 20B. Be placed.

  A merged exhaust pipe 24 is connected to the downstream ends of the first and second exhaust pipes 22 and 23 below the engine body 18. Moreover, the length of the first exhaust pipe 22 is set shorter than the length of the second exhaust pipe 23.

  5 and 6, the merged exhaust pipe 24 includes a pair of half members 27 and 28 coupled to each other and a pair of side wall forming members 29 and 30 provided between the half members 27 and 28. The first and second individual pipe portions 24a, 24b having both side wall forming members 29, 30 as inner side walls and the downstream ends of the first and second individual pipe portions 24a, 24b are used in common. It has a converging pipe portion 24c connected to each other and is formed in a substantially Y shape. Moreover, the length of the first individual pipe portion 24a is set to be shorter than the length of the second individual pipe portion 24b, and the upstream ends of the first and second individual pipe portions 24a and 24b can be expanded and contracted. First and second mouthpieces 31 and 32 each having a pair of slits 33... 34 are formed in a cylindrical shape, and are joined to the inner surfaces of the first and second mouthpieces 31 and 32. An annular stepped portion 31a, 32a facing the side opposite to 24 is formed.

  Ring-shaped stoppers 35 and 36 are fixed to the outer peripheries near the downstream ends of the first and second exhaust pipes 22 and 23, and the downstream end of the first exhaust pipe 23 to which the annular gasket 37 is attached is arranged on the outer periphery. The fastening band 39 is fitted into the first mouthpiece 31 together with the stopper 35 and the gasket 37 while the gasket 37 is sandwiched between the step portion 31a and the stopper 35, and the first mouthpiece 31 is wound around the outer periphery thereof. The downstream end of the first exhaust pipe 23 is connected to the first individual pipe portion 24a of the merging exhaust pipe 24 by tightening at. Further, the downstream end of the second exhaust pipe 23 to which the annular gasket 38 is mounted on the outer periphery is arranged in the second mouthpiece 32 together with the stopper 36 and the gasket 38 while sandwiching the gasket 38 between the stepped portion 32a and the stopper 36. The downstream end of the second exhaust pipe 23 is connected to the second individual pipe portion 24b of the merged exhaust pipe 24 by fastening the second mouthpiece 32 with a fastening band 40 wound around the outer periphery of the second mouthpiece 32. .

  By the way, the downstream end of at least one of the first and second exhaust pipes 22 and 23, in this embodiment, the downstream of the first exhaust pipe 22 having the shorter length of the first and second exhaust pipes 22 and 23. The upstream end of the throttle pipe 41 which is a member different from the first exhaust pipe 22 is fixed to the end portion. Further, the downstream end of the throttle pipe 41 protruding from the downstream end of the first exhaust pipe 22 is inserted into at least one individual pipe part of the first and second individual pipe parts 24a and 24b included in the merged exhaust pipe 24. In this embodiment, the downstream end of the throttle tube 41 is inserted into the shortest first individual tube portion 24a among the first and second individual tube portions 24a, 24b.

  The throttle pipe 41 is formed in a stepped cylindrical shape having an enlarged diameter portion 41 a at the upstream end, and the enlarged diameter inserted into the first exhaust pipe 22 from the downstream end of the first exhaust pipe 22. The portion 41a is fixed to the inner surface near the downstream end of the first exhaust pipe 22 by welding or the like. In addition, the throttle pipe 41 is fixed to the first exhaust pipe 22 so as to partially protrude from the downstream end of the first exhaust pipe 22.

  A cylindrical collar 42 penetrating the throttle pipe 41 is fixed to the inner periphery of the downstream end of the first exhaust pipe 22 by welding or the like so that a part thereof protrudes from the first exhaust pipe 22. The outer periphery of 41 is fixed to the inner periphery of the collar 42 by welding or the like.

  Thus, a portion of the throttle pipe 41 protruding from the downstream end of the first exhaust pipe 22 is inserted into the first individual pipe portion 24a. Moreover, the downstream end of the throttle pipe 41 is disposed behind the downstream end of the second exhaust pipe 23 connected to the second individual pipe portion 24b.

  Referring to FIGS. 7 and 8 together, the first sound absorbing means 44 is provided in the merged exhaust pipe 24 in the vicinity of the downstream end of the throttle pipe 41. The first sound absorbing means 44 is filled with a sound absorbing material 45 made of, for example, stainless steel, allowing the flow of exhaust gas from the individual tube portions 24a, 24b between the first and second individual tube portions 24a, 24b. It is made up of.

  That is, the side wall forming members 29, 30 forming the inner side walls of the first and second individual pipe portions 24a, 24b are made of a perforated plate having a large number of small holes 46, 47, and the side walls thereof. A sound absorbing material 45 is filled in a sound absorbing chamber 48 formed between the half members 27 and 28 and the side wall members 29 and 30 outside the forming members 29 and 30.

  In FIG. 9, a second sound absorbing means 49 is provided at an intermediate portion of the merging pipe portion 24 c in the merging exhaust pipe 24. The second sound absorbing means 49 is formed in a cylindrical shape by a perforated plate having a whole circumference bulging portion 50 swelled radially outward over the whole circumference and formed in the merging pipe portion 24 c and a large number of small holes 52. An annular sound absorbing chamber 53 formed between the cylindrical member 51 and the cylindrical member 51 fixed to the inner surface of the merging pipe portion 24c is filled with a stainless steel sound absorbing material 54.

  In FIG. 10, a sensor mounting pipe 55 for attaching an oxygen sensor (not shown) is fixed to the upper part of the merging pipe portion 24c on the downstream side of the second sound absorbing means. Below, the third sound absorbing means 56 is provided in the junction pipe portion 24c. The third sound-absorbing means 56 is a perforated plate having an arc-shaped cross section that has a lower bulging portion 57 that bulges outward in the radial direction and is formed at the lower portion of the merging pipe portion 24c, and a large number of small holes 59. The sound absorbing chamber 60 formed between the bent member 58 and the bent member 58 fixed to the inner surface of the junction pipe portion 24c is filled with a sound absorbing material 61 made of stainless steel.

  In FIG. 9 again, the catalytic converter 25 has a casing 63 connected to the downstream end of the merging pipe portion 24c in the merging exhaust pipe 24, and an exhaust passage 65 formed in the casing 63 through the merging pipe portion 24c. A catalyst 64 is disposed on the surface.

  Next, the operation of this embodiment will be described. At the downstream end portion of the first exhaust pipe 22 which is at least one of the first and second exhaust pipes 22 and 23, a throttle which is a separate member from the first exhaust pipe 22 is provided. The pipe 41 is fixed so as to partially protrude from the downstream end of the first exhaust pipe 22, and the portions of the throttle pipe 41 protruding from the downstream end of the first exhaust pipe 22 have different lengths from each other. The first and second individual pipe portions 24a and 24b provided in the merged exhaust pipe 24 are inserted into the shortest first individual pipe portion 24a.

  That is, the throttle pipe 41 is a separate member from the first exhaust pipe 22 and is fixed to the downstream end of the first exhaust pipe 22, so that the size of the throttle pipe 41 is independent of the first exhaust pipe 22. The accuracy can be increased, and the design can be changed by the throttle tube 41 alone, thereby increasing the degree of design freedom.

  In addition, since the first sound absorbing means 44 is provided in the merging exhaust pipe 24 in the vicinity of the downstream end of the throttle pipe 41 and the throttle pipe 41 has a high degree of freedom in shape, the merging is performed in the vicinity of the downstream end of the throttle pipe 41. The first sound absorbing means 44 can be provided in the exhaust pipe 24, and an excellent sound absorbing effect by the first sound absorbing means 44 can be obtained by appropriately determining the downstream end position of the throttle pipe 41.

  In addition, the upstream ends of the first and second exhaust pipes 22 and 23 having different lengths are connected to the engine body 18 having a pair of banks BA and BB having a V shape. The upstream end of the throttle pipe 41 is fixed to the downstream end portion of the shorter first exhaust pipe 22 of 22 and 23, and the downstream end of the throttle pipe 41 is closer to the motorcycle than the downstream end of the second exhaust pipe 23. It is arranged on the rear side along the front-rear direction. Thereby, in view of the arrangement space and layout associated with the multi-cylinder engine E mounted on the motorcycle being a V-type multi-cylinder engine, the shape and length of the first and second exhaust pipes 22 and 23 are particularly limited. Although restricted, the throttle pipe 41 is fixed to the downstream end of the shortest first exhaust pipe 22 so as to improve the output characteristics in the middle and low speed ranges, and the engine output characteristics can be easily changed. Can do.

  That is, as shown by the solid curve in FIG. 11, the throttle pipe 41 fixed to the downstream end of the first exhaust pipe 22 is throttled to the downstream end of the first exhaust pipe 22 as shown by the broken line in FIG. Compared with the case where the tube is not fixed, the shaft torque and output in the middle and low speed ranges can be increased.

  Further, in the engine body 18, first and second exhaust pipes having upstream ends connected to exhaust ports 20A, 20B provided on opposite sides of both banks BA, BB arranged in the front-rear direction of the motorcycle. The downstream ends of 22 and 23 are disposed below the engine body 18 and between the exhaust ports 20A and 20B of both banks BA and BB, and below the engine body 18 at the downstream ends of the first and second exhaust pipes 22 and 23. A combined exhaust pipe 24 is connected, and a catalyst 64 is disposed in an exhaust passage 65 on the downstream side of the combined exhaust pipe 24.

  According to such an arrangement, the length of the exhaust pipes 22 and 23 from the pair of banks BA and BB to the merged exhaust pipe 24 is set as short as possible, and the temperature difference of the exhaust gas merged in the merged exhaust pipe 24 is reduced. Thus, the purification performance of the catalyst 64 on the downstream side of the merged exhaust pipe 24 can be stabilized. Moreover, the distance from the first and second exhaust pipes 22 and 23 to the catalyst 64 can be secured, the temperature of the exhaust gas contacting the catalyst 64 can be made uniform, and the reduction in purification efficiency at the catalyst 64 can be suppressed. Can do.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.

1 is a side view of a motorcycle. FIG. 2 is a front view of the engine and the exhaust device viewed from the direction of arrow 2 in FIG. 1. FIG. 3 is a view taken in the direction of arrow 3 in FIG. 2. It is the top view which looked at a part of exhaust system from the arrow 4 direction of FIG. 3, omitting an engine. FIG. 5 is an enlarged view of the portion indicated by the arrow 5 in FIG. 3 in the exhaust device, and an enlarged view of the portion indicated by the arrow 5 in FIG. 3. FIG. 6 is an enlarged sectional view taken along line 6-6 in FIG. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 6. FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 6. FIG. 9 is an enlarged cross-sectional view taken along line 9-9 in FIG. 5. FIG. 10 is a sectional view taken along line 10-10 in FIG. It is an output characteristic figure of an engine.

Explanation of symbols

18 ... Engine main bodies 20A, 20B ... Exhaust ports 22, 23 ... Exhaust pipe 24 ... Merged exhaust pipes 24a, 24b ... Individual pipe part 24c ... Merged pipe part 26 ... Exhaust Muffler 41 ... throttle tube 44 ... sound absorbing means 64 ... catalyst 65 ... exhaust passage BA, BB ... bank E ... multi-cylinder engine

Claims (4)

  A plurality of exhaust pipes (22, 23) whose upstream ends are connected to the engine body (18) of the multi-cylinder engine (E) and a plurality of exhaust pipes (22, 23) that are individually connected to the downstream ends thereof A combined exhaust pipe (24) comprising an individual pipe section (24a, 24b) and a merging pipe section (24c) in which downstream ends of the individual pipe sections (24a, 24b) are connected in common, and the merging pipe section (24c) And an exhaust muffler (26) connected to the downstream end of each of the exhaust pipes (22, 23), and the downstream end of the throttle pipe (41) connected to at least one downstream end of each of the exhaust pipes (22, 23). In the exhaust device for a multi-cylinder engine for a motorcycle inserted into at least one of the pipe portions (24a, 24b), the throttle pipe (41), which is a separate member from the exhaust pipe (22, 23), has at least one. Two exhaust pipes (22) at the downstream end thereof. Exhaust system for a motorcycle for a multi-cylinder engine, characterized in that it is.   The exhaust system for a multi-cylinder engine for a motorcycle according to claim 1, wherein a sound absorbing means (44) is provided in the merging exhaust pipe (24) in the vicinity of the downstream end of the throttle pipe (41).   The shortest exhaust pipe (22, 23) of the plurality of exhaust pipes (22, 23) having an upstream end connected to the engine body (18) having a pair of banks (BA, BB) having a V shape and different lengths from each other. 22) the upstream end of the throttle pipe (41) is fixed to the downstream end of the throttle pipe (41), and the downstream end of the throttle pipe (41) is the shortest individual pipe section (24a) among the plurality of individual pipe sections (24a, 24b). Or the rear end of the other exhaust pipe (23) other than the shortest exhaust pipe (22), the rear end along the front-rear direction of the motorcycle. 2. An exhaust device for a multi-cylinder engine for a motorcycle according to 2.   Of exhaust pipes (22, 23) whose upstream ends are connected to exhaust ports (20A, 20B) provided on opposite sides of both banks (BA, BB) arranged in the front-rear direction of the motorcycle. The downstream end is disposed below the engine body (18) and between the exhaust ports (20A, 20B) of the banks (BA, BB), and the engine body is disposed at the downstream end of the exhaust pipes (22, 23). The merging exhaust pipe (24) is connected below (18), and a catalyst (64) is disposed in an exhaust passage (65) downstream of the merging exhaust pipe (24). 3. An exhaust device for a multi-cylinder engine for a motorcycle according to 3.

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