JP2016023574A - Exhaust pipe for saddle-riding type vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress or control reflection waves of exhaust pressure without increasing an arrangement space or without deteriorating the degree of freedom in the layout of an exhaust pipe.SOLUTION: In an exhaust pipe 13 which is provided on a motor cycle and in which exhaust gas from an engine flows, a chamber structure 21 is provided in a portion of the exhaust pipe 13 near to the engine. The chamber structure 21 is configured to comprise an inner cylinder part 22, an outer cylinder 23 provided on the outer peripheral side of the inner cylinder part 22, a chamber space 24 formed between the inner cylinder part 22 and the outer cylinder part 23, and communication holes 25 formed in the inner cylinder part 22 and providing communication between the inside of the inner cylinder part 22 and the inside of the chamber space 24. The chamber space 24 absorbs increase and decrease of exhaust pressure and reflection waves of the exhaust pressure can be suppressed. Further, forming the chamber space 24 in a part of the exhaust pipe 13 makes it possible to save the space and secure the degree of freedom in the layout of the exhaust pipe 13.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a straddle-type vehicle exhaust pipe used in a straddle-type vehicle such as a motorcycle.

  A straddle-type vehicle such as a motorcycle includes an engine, an exhaust pipe connected to the engine, and an exhaust muffler connected to the exhaust pipe on the downstream side in the exhaust direction (see, for example, Patent Document 1 below) ). Exhaust gas generated by combustion in the engine flows out from the exhaust port of the engine, circulates in the exhaust pipe, and travels to the exhaust muffler. The exhaust pipe is required to have a function of efficiently circulating the exhaust gas.

JP 2012-122402 A

  However, in the exhaust pipe, a reflected wave of the exhaust pressure is generated, and if this works at a positive pressure with respect to the combustion chamber of the engine at the timing when the intake / exhaust valve open wraps, it interferes with the pressure in the combustion chamber. Reduce intake efficiency. As a result, a torque decrease occurs at a specific rotational speed, which may cause a deterioration in driving feeling and a decrease in fuel consumption.

  Patent Document 1 describes an exhaust device that can provide a chamber outside the exhaust pipe, provide a passage communicating with the chamber in the exhaust pipe, and allow exhaust gas to flow from the exhaust pipe into the chamber. According to this exhaust system, it is considered that the exhaust gas is allowed to flow through the chamber, thereby suppressing or controlling the reflected wave of the exhaust pressure and suppressing the influence of the reflected wave on the engine operation as described above.

  However, in a saddle-ride type vehicle, it is difficult to secure a space for providing a chamber having a constant volume outside the exhaust pipe, and the number of parts and weight increase by attaching the chamber to the outside of the exhaust pipe. There is a problem of doing.

  Further, the exhaust device described in Patent Document 1 employs a structure in which the chamber is directly attached to the exhaust pipe from the outside thereof, and efficiently secures a space for providing the chamber. There is a problem that the layout of the tube is limited.

  The present invention has been made in view of the above-described problems, for example, and an object of the present invention is to provide a reflected wave of the exhaust pressure without increasing the arrangement space or without impairing the flexibility of the exhaust pipe layout. An object of the present invention is to provide a straddle-type vehicle exhaust pipe that can be suppressed or controlled.

  In order to solve the above problems, a first saddle-riding vehicle exhaust pipe of the present invention is a straddle-type vehicle exhaust pipe that connects an engine and an exhaust muffler in the saddle-riding vehicle, A chamber structure is provided in at least a part of the exhaust pipe, and the chamber structure includes an inner cylinder part, an outer cylinder part provided on an outer peripheral side of the inner cylinder part, the inner cylinder part, and the outer cylinder. A chamber space formed between the inner cylinder portion and a communication hole formed in the inner cylinder portion and communicating between the inner cylinder portion and the chamber space.

  By causing a part of the exhaust gas to flow into the chamber space, it is possible to absorb the increase and decrease of the exhaust pressure and suppress or control the reflected wave of the exhaust pressure. Further, the exhaust pipe has a double cylinder structure, and a chamber space is formed between the two cylinder portions, whereby the chamber structure can be provided inside the exhaust pipe. Thereby, suppression or control of the reflected wave of the exhaust pressure can be realized without increasing the arrangement space, the number of parts and the weight, or without impairing the flexibility of the exhaust pipe layout.

  The second saddle type vehicle exhaust pipe of the present invention is the above-described first saddle type vehicle exhaust pipe of the present invention, wherein the exhaust pipe is a plurality of exhaust mufflers connected in series. The exhaust muffler arranged on the most upstream side in the exhaust direction is connected to the engine.

  Thereby, the chamber structure can be brought close to the engine, and the increase and decrease of the exhaust pressure can be easily absorbed.

  The third saddle type vehicle exhaust pipe according to the present invention is the above-described first or second saddle type vehicle exhaust pipe according to the present invention, wherein the communication hole extends in a circumferential direction of the inner cylinder portion. It is characterized in that a plurality are formed at intervals.

  Thus, by forming a plurality of communication holes and arranging these communication holes at intervals in the circumferential direction, noise generated when exhaust gas passes through the communication holes can be suppressed. .

  According to a fourth saddle-type vehicle exhaust pipe of the present invention, in any one of the first to third saddle-type vehicle exhaust pipes of the present invention described above, the communication hole is an extension of the inner cylinder portion. It is arranged in a portion closer to the engine than the middle in the direction.

  Thus, by making the communication hole approach the engine, it is possible to easily absorb the increase and decrease in the exhaust pressure.

  According to the present invention, it is possible to suppress or control the reflected wave of the exhaust pressure without increasing the arrangement space or without impairing the flexibility of the exhaust pipe layout.

It is explanatory drawing which shows the motorcycle provided with the exhaust pipe by embodiment of this invention. It is explanatory drawing which shows the exhaust apparatus which has an exhaust pipe by embodiment of this invention. It is a perspective view which shows the exhaust apparatus which has an exhaust pipe by embodiment of this invention. It is a longitudinal cross-sectional view which shows the part in which the chamber structure was formed in the exhaust pipe by embodiment of this invention. It is a cross-sectional view of the chamber structure seen from the arrow VV direction in FIG. It is explanatory drawing which shows the flow of the exhaust gas between an inner cylinder part and chamber space in the chamber structure of the exhaust pipe by embodiment of this invention.

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

  FIG. 1 shows a motorcycle as a specific example of a saddle-ride type vehicle. In FIG. 1, a motorcycle 1 includes a body frame 2, and an engine 3 is mounted on the body frame 2. A steering shaft 4 is provided on the front side of the body frame 2, a front wheel 6 is suspended on the lower side of the steering shaft 4 via a front fork 5, and a handle 7 is attached on the upper side of the steering shaft 4. . A swing arm 8 is provided on the rear side of the body frame 2, and a rear wheel 9 is attached to the rear part of the swing arm 8. Further, an exhaust device 11 is provided mainly under the body frame 2.

  FIG. 2 or 3 shows the exhaust device 11. In FIG. 2, the exhaust device 11 includes an exhaust pipe mouth 12, a first exhaust pipe 13, a first exhaust muffler 14, a second exhaust pipe 15, and a second exhaust muffler 16 that are embodiments of the present invention. I have. One end side of the first exhaust pipe 13 is connected to the exhaust port of the engine 3 via the exhaust pipe base 12, and the other end side of the first exhaust pipe 13 is connected to the inlet of the first exhaust muffler 14. ing. In addition, one end side of the second exhaust pipe 15 is connected to the outlet of the first exhaust muffler 14, and the other end side of the second exhaust pipe 15 is connected to the inlet of the second exhaust muffler 16. .

  In the exhaust device 11, the layout of the exhaust pipes 13 and 15 and the exhaust mufflers 14 and 16 is set as follows. That is, as shown in FIG. 3, the first exhaust pipe 13 protrudes from the exhaust port of the engine 3 toward the front side of the motorcycle 1, curves immediately downward, and then straightens toward the lower side of the body frame 2. Then, after gently curving backward, it reaches the inlet of the first exhaust muffler 14 disposed behind the engine 3 and below the vehicle body frame 2. The second exhaust pipe 15 protrudes from the outlet of the first exhaust muffler 14 toward the right side of the motorcycle 1 and then immediately curves backward, and is disposed at the lower right side of the rear part of the motorcycle 1. The inlet of the second exhaust muffler 16 is reached.

  FIG. 4 shows a longitudinal section of a chamber structure formed in a part of the first exhaust pipe 13. FIG. 5 shows a cross section of the chamber structure as seen from the direction of arrows V-V in FIG. FIG. 6 shows the action of suppressing the reflected wave of the exhaust pressure by the chamber structure.

  Of the plurality of exhaust mufflers 14, 16 arranged in series in the exhaust device 11, the first exhaust pipe 13 connecting the first exhaust muffler 14 arranged on the most upstream side in the exhaust direction and the engine 3. A chamber structure 21 is formed inside a part of the chamber. Further, the chamber structure 21 is formed in a portion closer to the engine 3 than the middle in the extending direction of the first exhaust pipe 13. Specifically, the first exhaust pipe 13 protrudes from the exhaust port of the engine 3 and immediately curves, and then extends downward linearly. In the first exhaust pipe 13, the first exhaust pipe 13 extends downward linearly. The chamber structure 21 is formed in a portion (a portion surrounded by a two-dot chain line in FIG. 2 or 3).

  As shown in FIG. 4, the chamber structure 21 includes a cylindrical inner cylinder portion 22, a cylindrical outer cylinder portion 23 provided on the outer peripheral side of the inner cylinder portion 22, and the inner cylinder portion 22 and the outer cylinder portion 23. And a plurality of communication holes 25 that are formed in the inner cylinder portion 22 and communicate between the inner cylinder portion 22 and the chamber space 24.

  The inner cylinder part 22 and the outer cylinder part 23 are formed of a material generally used for an exhaust pipe of a motorcycle, such as iron, stainless steel, and titanium. Further, the inner cylinder part 22 and the outer cylinder part 23 are arranged concentrically, and the inner diameter of the outer cylinder part 23 is larger than the outer diameter of the inner cylinder part 22. Thereby, an annular chamber space 24 is formed between the inner cylinder part 22 and the outer cylinder part 23. Further, the inner cylinder part 22 and the outer cylinder part 23 are respectively coupled at both ends 26 and 27 in the length direction of the region where the chamber structure 21 is arranged in the first exhaust pipe 13. Thereby, the chamber space 24 is a closed space except for the communication hole 25. The inner cylinder portion 22 has an inner diameter of, for example, approximately 20 mm to 30 mm, and the radial separation distance between the inner cylinder portion 22 and the outer cylinder portion 23, that is, the width dimension of the chamber space 24 is, for example, approximately 5 mm to 10 mm.

  Further, each communication hole 25 is disposed in a portion closer to the engine 3 than the middle in the extending direction of the inner cylinder portion 22. In other words, each communication hole 25 is disposed in a portion closer to the engine 3 than the middle in the length direction of the region where the chamber structure 21 is disposed in the first exhaust pipe 13. Further, each communication hole 25 is arranged in parallel in the circumferential direction of the inner cylinder portion 22 at one location close to the engine 3 in the extending direction of the inner cylinder portion 22. As shown in FIG. 5, the respective communication holes 25 are arranged at predetermined intervals in the circumferential direction of the inner cylinder portion 22, specifically, radially arranged at equal intervals in the circumferential direction of the inner cylinder portion 22. Has been. In the present embodiment, for example, four communication holes 25 are arranged at intervals of 90 degrees. The diameter of each communication hole 25 is, for example, about 4 mm to 6 mm.

  In the chamber structure having such a configuration, the reflected wave of the exhaust pressure can be suppressed by absorbing the increase and decrease of the exhaust pressure by the chamber space 24. That is, as shown in FIG. 6, most of the exhaust gas exhausted from the engine 3 circulates in the inner cylinder portion 22 in the exhaust direction. On the other hand, when a part of the exhaust gas flowing in the inner cylinder portion 22 flows in the direction opposite to the exhaust direction due to the reflected wave of the exhaust pressure, a part of the exhaust gas in the reverse direction passes through each communication hole 25. Into the chamber space 24. As a result, the exhaust pressure in the direction opposite to the exhaust direction decreases, and the reflected wave of the exhaust pressure is suppressed. When the pressure in the inner cylinder portion 22 is lower than the pressure in the chamber space 24, the exhaust gas in the chamber space 24 returns to the inner cylinder portion 22 through the communication holes 25.

  As described above, according to the first exhaust pipe 13 according to the embodiment of the present invention, the first exhaust pipe 13 has a double cylinder structure including the inner cylinder part 22 and the outer cylinder part 23, and the communication hole 25 is provided between the two cylinder parts. Since the chamber structure 21 in which the chamber space 24 communicating with the inside of the inner cylinder portion 22 is defined is formed in a part of the exhaust pipe 13, the reflected wave of the exhaust pressure is suppressed or controlled. The function can be imparted to the motorcycle 1 without increasing the arrangement space.

  Further, according to the first exhaust pipe 13 of the embodiment of the present invention, the function of suppressing or controlling the reflected wave of the exhaust pressure can be provided to the motorcycle 1 without increasing the number of parts and the weight of the motorcycle 1. Can be granted. That is, some motorcycles already employ an exhaust pipe having a double cylinder structure at the present time. In the case of such a motorcycle, the chamber structure 21 can be added to the exhaust pipe only by making a small design change such as forming a communication hole in the inner cylinder of the exhaust pipe having a double cylinder structure that is currently employed. Can be formed. Therefore, the chamber structure 21 can be formed in the exhaust pipe without adding new parts. Since no new parts are added when forming the chamber structure 21, the weight of the motorcycle does not increase.

  Further, according to the first exhaust pipe 13 of the embodiment of the present invention, since the chamber space 24 can be formed inside the exhaust pipe 13, other parts mounted on the motorcycle 1, Interference with the apparatus can be prevented, and thereby the degree of freedom in layout of the exhaust pipe 13 can be ensured.

  Further, according to the first exhaust pipe 13, since the chamber space 24 is formed between the inner cylinder portion 22 and the outer cylinder portion 23, the volume of the chamber space 24 can be adjusted and the arrangement of the chamber space can be adjusted. Easy to select. For example, if the chamber space 24 is formed long along the first exhaust pipe 13, the volume can be increased, and if it is formed short, the volume can be reduced. This makes it possible to easily control the reflected wave of the exhaust pressure.

  Further, according to the first exhaust pipe 13, since the chamber space 24 surrounds the inner cylinder portion 22, the exhaust temperature is hardly lowered, and the temperature rise of the catalyst at the time of cold start can be promoted.

  In addition, according to the embodiment of the present invention, the chamber structure 21 is provided in a part of the first exhaust pipe 13 that connects the first exhaust muffler 14 disposed on the most upstream side in the exhaust direction and the engine 3. By forming or forming the chamber structure 21 in a portion closer to the engine 3 than in the middle of the extension direction of the first exhaust pipe 13, it is possible to easily absorb the increase and decrease in the exhaust pressure. The effect of suppressing the reflected wave of pressure can be enhanced. Further, in the chamber structure 21, each communication hole 25 is arranged closer to the engine 3 than the middle in the extension direction of the inner cylinder portion 22, so that the increase and decrease in the exhaust pressure can be more easily absorbed. The effect of suppressing the reflected wave can be further enhanced.

  Further, in the chamber structure 21, by forming a plurality of communication holes 25 in the inner cylinder portion 22, it is possible to suppress noise generated when exhaust gas passes through the communication holes 25. Further, by arranging the plurality of communication holes 25 radially, it is possible to enhance the absorption effect of the increase / decrease of the exhaust pressure and the noise suppression effect.

  In the above-described embodiment, in the chamber structure 21, the case where the four communication holes 25 are radially arranged at one location in the extending direction of the inner cylinder portion 22 is described as an example. The arrangement is not limited to this. One to three, or five or more communication holes may be provided in the inner cylinder portion 22. Further, the communication holes may be provided at two or more locations in the extending direction of the inner cylinder portion 22. Further, the communication holes may not be arranged radially over the entire circumference of the inner cylinder part 22, but may be arranged only in a part of the inner cylinder part 22 in the circumferential direction.

  Further, in the above-described embodiment, the case where the chamber structure 21 is arranged in a portion extending linearly downward in the first exhaust pipe 13 has been described as an example. However, the chamber structure 21 is the first exhaust pipe. You may arrange | position in 13 other places. Further, the chamber structure may be formed over the entire length of the first exhaust pipe 13.

  Further, in the above-described embodiment, the case where one first exhaust pipe 13 is provided between the engine 3 and the first exhaust muffler 14 is taken as an example. The present invention can also be applied to a motorcycle in which a plurality of exhaust pipes are arranged in parallel with a muffler. In this case, a chamber structure may be provided for each of these exhaust pipes.

  Further, the exhaust device or the exhaust pipe of the present invention can be applied not only to a motorcycle but also to other straddle-type vehicles such as an automatic tricycle, an automatic four-wheel vehicle such as a buggy.

  The present invention can be modified as appropriate without departing from the spirit or concept of the invention which can be read from the claims and the entire specification, and the exhaust pipe for a straddle-type vehicle with such a modification is also described in this document. It is included in the technical idea of the invention.

1 Motorcycle (saddle-ride type vehicle)
3 Engine 11 Exhaust device 12 Exhaust pipe opening 13, 15 Exhaust pipe 14, 16 Exhaust muffler 21 Chamber structure 22 Inner cylinder part 23 Outer cylinder part 24 Chamber space 25 Communication hole 26, 27 Both ends

Claims (4)

  A straddle-type vehicle exhaust pipe that connects between an engine and an exhaust muffler in a straddle-type vehicle, wherein a chamber structure is provided in at least a part of the exhaust pipe, and the chamber structure includes an inner cylinder Part, an outer cylinder part provided on the outer peripheral side of the inner cylinder part, a chamber space formed between the inner cylinder part and the outer cylinder part, and the inner cylinder formed in the inner cylinder part A straddle-type vehicle exhaust pipe comprising a communication hole communicating between the inside of the chamber and the chamber space.   2. The straddle type according to claim 1, wherein the exhaust pipe is connected between the engine and an exhaust muffler disposed upstream in the exhaust direction among a plurality of exhaust mufflers connected in series. Exhaust pipe for vehicles.   3. The straddle-type vehicle exhaust pipe according to claim 1, wherein in the chamber structure, a plurality of the communication holes are formed at intervals in a circumferential direction of the inner cylinder portion.   4. The straddle-type vehicle according to claim 1, wherein, in the chamber structure, the communication hole is disposed at a portion closer to the engine than an intermediate direction of extension of the inner cylinder portion. 5. Exhaust pipe.

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