JP3773597B2 - Motorcycle exhaust system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust device for a motorcycle, and more particularly to an exhaust device provided with a plurality of independent exhaust passages in a multi-cylinder engine.
[0002]
[Prior art]
In Japanese Patent Laid-Open No. 8-28244, the appearance of a single muffler is provided with a partition wall in the lengthwise direction, a plurality of expansion chambers are provided in a vertically split shape, and an exhaust pipe of a multi-cylinder engine is individually connected to each expansion chamber. Thus, there is shown an exhaust device for a motorcycle in which a plurality of independent exhaust passages are formed.
[0003]
In the present invention, the direction along the length direction of the muffler is referred to as a longitudinal direction, and a direction substantially perpendicular to the longitudinal direction is referred to as a laterally (circular) direction or a transverse direction.
[0004]
[Problems to be solved by the invention]
As described above, if the expansion chamber is formed in a vertically split shape, if the expansion chamber cross-sectional area ratio is increased in order to increase the silencing effect, the entire muffler must be thickened, and the appearance, vehicle body mounting, and bank angle are secured. There are many restrictions on this point.
[0005]
It is also desired to prevent the outer surface of the muffler from partially discoloring due to high temperature exhaust. The present invention aims to solve such problems.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, an exhaust device for a motorcycle according to the present invention comprises a plurality of exhaust pipes extending from a plurality of cylinders of an engine, and a muffler to which the downstream ends of these exhaust pipes are connected. A plurality of expansion chambers are defined by partition walls formed in the transverse direction inside the muffler, and these expansion chambers are connected to specific exhaust pipes, thereby forming an exclusive exhaust passage for each exhaust pipe. In a two-wheeled vehicle exhaust system, a plurality of expansion chambers are formed side by side in the length direction of the muffler, and each exhaust pipe is provided with an independent tail pipe and a dedicated exhaust passage is formed for each exhaust pipe. All of the expansion chambers are arranged in the length direction of the muffler .
[0007]
In this case, Ru can substantially match the blowing direction of the exhaust to the longitudinal direction of the muffler in each expansion chamber.
[0008]
Further, a muffler body mounting bracket can be attached to a portion of the muffler outer periphery where the outer peripheral portion of the partition wall abuts.
[0009]
【The invention's effect】
By arranging a plurality of expansion chambers in the muffler length direction and connecting each expansion chamber to a specific exhaust pipe, a dedicated exhaust passage is formed for each exhaust pipe.
[0010]
For this reason, although it is a single muffler in appearance, an individual exhaust sound can be generated for each exhaust pipe.
[0011]
In addition, by arranging the expansion chambers in the length direction, the usable portion of each expansion chamber is substantially the entire cross-sectional direction of the muffler, so the cross-sectional area ratio can be increased, and the silencing effect is improved without increasing the size of the muffler. it can.
[0012]
Further, when it is desired to increase the volume of the expansion chamber, it can be extended in the length direction of the muffler and is not subject to restrictions in securing the bank angle, and can be easily handled.
[0013]
In addition, since the exhaust blow-off in each expansion chamber substantially coincides with the length direction of the muffler, it is difficult for the discharged exhaust to directly contact the muffler wall surface, and the cooling efficiency of the exhaust due to the increase in the volume of the expansion chamber is reduced. Since it is good, partial discoloration on the outer surface of the muffler due to the heat of the exhaust is not easily generated.
[0014]
Further, since the expansion chamber forming one exhaust passage can be divided into a plurality of parts in the length direction of the muffler, the arrangement of the partition walls is facilitated, and the degree of freedom in setting the partition walls is increased.
[0015]
Therefore, it is possible to firmly attach the vehicle body mounting bracket to the outer surface of the muffler by arranging the partition wall at the mounting position of the vehicle body and using the partition wall for reinforcement.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 2 shows the right side surface of a motorcycle equipped with a front / rear V-type two-cylinder engine to which the present invention is applied. The front exhaust pipe 3 is connected to the front cylinder 2 of the engine 1 and the rear side is connected to the rear cylinder 4. Each exhaust pipe 5 extends rearward.
[0017]
A downstream end of each exhaust pipe is connected to a front end portion of a single muffler 6, and tail pipes 7 and 8 extend rearward from the rear end portion.
[0018]
The muffler 6 extends long in the front-rear direction so as to cross the side surface of the rear wheel 9, and is attached to the rear end portion of the muffler support stay 11 with a bolt 12 in a vehicle body mounting bracket 10 attached to an intermediate portion.
[0019]
The muffler support stay 11 is a substantially L-shaped member formed by aluminum die casting or the like, and is arranged to extend in the front-rear direction below the muffler 6 so as to substantially follow the muffler 6.
[0020]
The front end 13 side of the muffler support stay 11 is bent upward and is attached to the rear side surface of the crankcase 14 by two bolts 15 a and 15 b at the upper and lower portions, and the lower end of the pivot plate 16 is bolted to the lower end of the pivot plate 16 near the bent portion. Installed.
[0021]
In the figure, reference numerals 16a and 16b denote engine mounts attached to the pivot plate 16, respectively, 18 a rear swing arm, 19 a rear stay, 20 a rear cushion unit, 21 a rear fender, 22 a seat, and 23 a seat. Rail, 24 is a rear down frame, 25 is a main frame, 26 is a fuel tank, 27 is a front down frame, 28 is a radiator, and 29 is a front fork.
[0022]
FIG. 3 is a view showing a detailed mounting structure of the muffler support stay 11 from the rear of the vehicle body. The upper end of the front end 13 is shared with the engine mount 16a by a bolt 15a penetrating the upper end of the rear end of the crankcase 14 to the left and right. It is tightened.
[0023]
A fastening seat surface 13a is formed at the lower portion of the front end portion 13, and is fastened together with a vibration isolating bush 16b by bolts 15b penetrating the lower portion of the rear end portion of the crankcase 14 to the left and right.
[0024]
An intermediate portion of the muffler support stay 11 is attached to a pivot plate 16 below the rear stay 19 by a bolt 17a at a connecting portion 16c at one end and a lower end portion of the pivot plate 16 by a bolt 17b at the other end via a link 16d. Yes.
[0025]
Reference numeral 9a in the figure is the axle of the rear wheel, L is a line indicating the bank angle θ, and the bank angle θ is sufficiently large.
[0026]
FIG. 4 is a diagram showing the attachment structure of the link 16d in detail. As is apparent from this figure, the connecting portion 16c at one end is formed by a collar 16g fitted around the bolt 17a and a washer 16f sandwiching the left and right ends. The periphery of the bolt 17a is rotatably connected.
[0027]
The bolt 17a passes through the collar 16g, the washer 16f, the pivot plate 16 and the collar 16h which is welded to the pivot plate 16 at the penetration portion, and is fastened by a nut 17c.
[0028]
An anti-vibration bush 16e is press-fitted into the other end of the link 16d, and this is sandwiched between the washer 16i and the end face of the boss portion 11a of the muffler support stay 11, and a bolt 17b penetrating the anti-vibration bush 16e is attached to the boss portion 11a. Are fastened to the screw holes 11b.
[0029]
FIG. 1 shows a longitudinal section of the muffler 6, and FIG. 5 shows a section taken along line 5-5 of FIG.
[0030]
The inside of the muffler 6 is divided into six expansion chambers from the first expansion chamber 40 to the sixth expansion chamber 45 by partition walls 30 to 34 provided in the transverse direction, and these expansion chambers are in the length direction of the muffler 6. Are arranged in series.
[0031]
The first expansion chamber 40 is formed between the partition wall 30 and the front wall 35, the rear end of the front exhaust pipe 3 is connected to a joint 36 provided on the front wall 35, and the rear of the rear exhaust pipe 5 is connected to a joint 37. The ends are connected.
[0032]
The rear end portion of the joint 36 is opened into the first expansion chamber 40 immediately after passing through the front wall 35, and serves as a blowout port for exhausting air.
[0033]
The rear end portion of the joint 37 is connected to the front end of the first communication pipe 50 in the first expansion chamber 40, and the first communication pipe 50 passes through the first expansion chamber 40, penetrates the partition wall 30, and is second. Opened into the expansion chamber 41.
[0034]
In addition, the 1st expansion chamber 40 part is the taper part 38 which swells toward back among the surrounding wall parts of the muffler 6. FIG.
[0035]
Thereafter, the structure of each expansion chamber is the same. Reference numeral 51 is a second communication pipe, 52 is a third communication pipe, 53 is a fourth communication pipe, and 54 is a fifth communication pipe.
[0036]
A front end portion of each communication pipe forms a discharge port, and a rear end portion forms a blow-out port, and the blow-out direction substantially coincides with the length direction of the muffler 6.
[0037]
The sixth expansion chamber 45 is formed between the partition wall 34 and the rear wall 39, and the front end of the tail pipe 7 that passes through the rear wall 39 passes through the sixth expansion chamber 45 and passes through the partition wall 34, thereby expanding the fifth expansion chamber. Opened into the chamber 44, the front end of the tail pipe 8 is opened into the sixth expansion chamber 45.
[0038]
A silencer cylinder 55 is attached to a portion of each tail pipe 7, 8 in the sixth expansion chamber 45, and the inside thereof is filled with glass wool 56, as shown by breaking the tail pipe 8 side. A small hole 57 is provided on the side surface.
[0039]
The rear end portions of the tail pipes 7 and 8 extend at an equal length from the rear wall 39, so that the appearance is improved.
[0040]
Further, as is apparent from FIG. 5, a recess 60 is formed inside the front portion of the muffler 6 in order to avoid interference with the vehicle body during installation, and the positions of the outlet and outlet in each expansion chamber are shifted laterally. The exhaust path in the expansion chamber is bent.
[0041]
As is apparent from the enlarged portion of FIG. 1, each partition wall (partition wall 33 in the illustrated enlarged portion) has a flange 61 on the outer peripheral portion, and this portion is in contact with the inner surface of the peripheral wall of the muffler 6 to form a double-sided reinforcing portion structure. It has become.
[0042]
A vehicle body mounting bracket 10 is superimposed on the outer surface of the reinforcing portion and is attached by welding.
[0043]
Next, the operation of this embodiment will be described. The exhaust from the front exhaust pipe 3 enters the first expansion chamber 40 from the joint 36 and expands, enters the second communication pipe 51, passes through the second expansion chamber 41, and then expands in the third expansion chamber 42 again. Further, it enters the fourth communication pipe 53 and passes through the fourth expansion chamber 43 and then expands in the fifth expansion chamber 44. Finally, it enters the tail pipe 7 and passes through the sixth expansion chamber 45 and is discharged to the atmosphere. .
[0044]
Exhaust gas from the rear exhaust pipe 5 expands in the second expansion chamber 41 through the first communication pipe 50 from the joint 37, passes through the third expansion chamber 42 through the third communication pipe 52, and then returns to the fourth. It expands in the expansion chamber 43, passes through the fifth expansion chamber 44 through the fifth communication pipe 54, expands again in the sixth expansion chamber 45, and is finally discharged from the tail pipe 8 into the atmosphere.
[0045]
Therefore, although the muffler 6 has a single appearance, the exhaust passages of the front exhaust pipe 3 and the rear exhaust pipe 5 are independently formed, and as a result, exhaust sounds for each cylinder are individually generated. Can be made.
[0046]
Moreover, since each expansion chamber is used exclusively for one of the exhaust passages, almost the entire cross section of the muffler 6 can be used as the cross section of the expansion chamber, and the cross-sectional area ratio can be increased.
[0047]
Therefore, since it is not necessary to make the muffler 6 thicker, it is possible to maintain a good appearance and to reduce restrictions when mounting the vehicle body.
[0048]
In particular, since it is not necessary to make the muffler 6 thick, the bank angle θ (FIG. 3) can be increased, which is advantageous in improving the running performance.
[0049]
Also, if you want to increase the volume of the expansion chamber, extend the expansion chamber in the length direction of the muffler 6 or divide it into multiple pieces and connect them in the length direction according to the number of exhaust passages. This can be expected to improve the silencing effect.
[0050]
Further, since the degree of freedom in the installation position of the partition wall is increased, for example, the partition wall 31 and the partition wall 33 are provided so as to be the mounting position of the vehicle body mounting bracket 10, and the vehicle body mounting bracket 10 is moved to the outer surface of the muffler 6. If it welds, the attachment part of the bracket 10 for vehicle body attachment will be reinforced with the partition 31 and the partition 33, Therefore Attachment strength can be raised.
[0051]
In addition, since the exhaust direction of the exhaust gas in each expansion chamber substantially coincides with the length direction of the muffler 6, it becomes difficult for high-temperature exhaust gas to directly contact the muffler 6, and partial discoloration of the muffler 6 surface is easily prevented. .
[0052]
At this time, since the positions of the outlet and the outlet are shifted in the transverse direction, the exhaust is not exhausted without being expanded, and sufficient expansion can be expected. Moreover, such a positional relationship between the blowout port and the discharge port can be easily realized by arranging the expansion chambers of the present invention in the length direction so that the cross section of each expansion chamber can be widened.
[0053]
FIG. 6 is a schematic cross-sectional view in the length direction according to the second embodiment having three exhaust passages. However, this embodiment is an example when the number of exhaust passages is three or more, and the present invention can naturally be applied even when there are four or more.
[0054]
First to third expansion chambers 75 to 77 are formed in the muffler 70 by first to fourth partition walls 71 to 74 that divide the inside in a ring shape in order from the upstream side to the downstream side of the exhaust. .
[0055]
The first system exhaust pipe 80 expands in the first expansion chamber 75, and then passes through the other second and third expansion chambers 76 and 77 by the first communication pipe 81 and is discharged downstream.
[0056]
The second system exhaust pipe 82 passes through the first expansion chamber 75 and expands in the second expansion chamber 76, and then passes through the third expansion chamber 77 by the second communication pipe 83 and is discharged downstream.
[0057]
The third system exhaust pipe 84 passes through the first expansion chamber 75 and the second expansion chamber 76, expands in the third expansion chamber 77, and is then discharged downstream by the third communication pipe 85.
[0058]
Note that the illustrated expansion chamber shows the first unit corresponding to the number of exhaust systems, and this unit can be repeatedly provided in the length direction of the muffler 70 if necessary.
[0059]
In this way, even when three exhaust pipes are connected, it is not necessary to increase the diameter of the muffler 70 as in the prior art, and it can be as thick as a muffler in a single cylinder engine.
[0060]
At this time, the exhaust direction in each expansion chamber is substantially the same as the length direction of the muffler 70, and the effects associated therewith can be similarly expected. Moreover, the other effect in previous embodiment can be anticipated similarly.
[0061]
The present invention is not limited to the above embodiment and can be variously modified. For example, even in a front and rear V-type engine, the rear end portions of the front exhaust pipe 3 and the rear exhaust pipe 5 are extended. The position can be matched by adjusting the expansion chamber.
[0062]
In addition, if a small hole or a small-diameter pipe is provided in the partition wall so that expansion chambers of different exhaust passages communicate with each other, the engine output characteristics and the tone of the exhaust sound can be adjusted.
[0063]
Thus, the exhaust passages separated for each exhaust pipe in the present invention are not completely independent as in the above-described embodiment, but may be substantially independent.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an exhaust system according to the present invention. FIG. 2 is a right side view of a motorcycle to which the present invention is applied. FIG. 3 is a view showing a muffler support structure from the rear of the vehicle body. FIG. 5 is a sectional view taken along line 5-5 in FIG. 1. FIG. 6 is a schematic sectional view in the length direction according to the second embodiment.
3: front exhaust pipe, 5: rear exhaust pipe, 6: muffler 6, 30: partition, 31: partition, 32: partition, 33: partition, 34: partition, 40: first expansion chamber, 41: second expansion Chamber: 42: third expansion chamber, 43: fourth expansion chamber, 44: fifth expansion chamber, 45: sixth expansion chamber

Claims (4)

A plurality of exhaust pipes extending from a plurality of cylinders of the engine and a muffler to which the downstream ends of these exhaust pipes are connected, and a plurality of expansion chambers are defined by partition walls formed in a transverse direction inside the muffler. In the exhaust device of a motorcycle, by connecting each of these expansion chambers to a specific exhaust pipe, a dedicated exhaust passage is formed for each exhaust pipe.
These multiple expansion chambers are arranged side by side in the length direction of the muffler, and each exhaust pipe has an independent tail pipe ,
An exhaust system for a motorcycle , wherein a plurality of expansion chambers that form dedicated exhaust passages for each of the exhaust pipes are arranged all at once in the length direction of the muffler .   2. The exhaust system for a motorcycle according to claim 1, wherein a direction in which exhaust gas is blown out in the expansion chamber is substantially coincident with a length direction of the muffler.   The exhaust device for a motorcycle according to claim 1 or 2, wherein the muffler mounting bracket is attached to a portion of the outer periphery of the muffler where the outer peripheral portion of the partition wall abuts. A plurality of expansion chambers that form a dedicated exhaust passage for each exhaust pipe are all arranged in the muffler lengthwise direction, and the first expansion chamber portion that is on the exhaust upstream side of the peripheral wall portion of the muffler 2. The exhaust device for a motorcycle according to claim 1, wherein the taper portion is tapered toward the rear .

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