JP3159285U - Exhaust device for saddle riding type vehicle and saddle riding type vehicle - Google Patents

Abstract

Disclosed is an exhaust device for a saddle-ride type vehicle that satisfies the requirements for noise reduction characteristics and is reduced in size. An exhaust system for a saddle-ride type vehicle includes an exhaust pipe connected to an engine and a silencer connected to the exhaust pipe. The exhaust pipe 20 includes a Helmholtz resonator 40, and the Helmholtz resonator 40 is filled with a sound absorbing material 45, and the Helmholtz resonator 40 further has an opening 42 communicating with the inside of the exhaust pipe 20. The opening 42 is formed at a location where the sound pressure inside the exhaust pipe 20 is high during engine operation. [Selection] Figure 5B

Description

  The present invention relates to a straddle-type vehicle exhaust device and a straddle-type vehicle.

  A muffler (exhaust device) used in a saddle-ride type vehicle (for example, a motorcycle) efficiently discharges exhaust gas discharged from an engine, and exhaust gas accompanying exhaust of high-pressure and high-temperature exhaust gas. It is required to satisfy two requirements of sound reduction or mute.

  In recent years when noise regulations have been tightened, there has been an increasing demand for noise reduction or silencing. Therefore, it is desired to achieve sound reduction or silencing while maintaining exhaust efficiency. A muffler for a motorcycle is disclosed in Patent Document 1, for example.

JP 2007-231784 A

  Considering the muffler design only from the exhaust efficiency, it is most preferable to extend the muffler (exhaust system) straight. However, this does not fit in the motorcycle body. Therefore, in order to reduce the exhaust resistance, the muffler is brought to the rear of the vehicle body so as not to bend as rapidly as possible. However, in practice, it is often difficult to get involved with the front wheels and the bank angle. Normally, the muffler with the ideal length for engine performance does not fit in the shape of the motorcycle as it is, and the muffler with the length close to the best in the performance is kept in the shape of the motorcycle while maintaining the smooth shape as much as possible. This design is very difficult compared to the muffler design of a passenger car.

  In addition to the exhaust efficiency, in motorcycles, the weight of the muffler has a great influence on maneuverability. In other words, the motorcycle has a light body, so even a weight of about 1 kg has a large effect on the motorcycle. In addition to the weight of the muffler, the fact that the center of gravity of the muffler is far is also a factor in handling the motorcycle Adversely affected.

  On the other hand, no matter how much the structure is devised, a certain amount of muffler capacity is required to enhance the silencing effect. In many cases, the muffler must be enlarged in order to meet the increasingly stringent noise regulations. In addition, if the metal plate constituting the muffler is thin, it vibrates and increases noise, so the muffler weight tends to be heavy. And the increase in the weight of the muffler deteriorates the maneuverability of the motorcycle.

  As described above, since the structure of the muffler of the motorcycle is determined based on various conflicting factors, it has been extremely difficult to realize a muffler that is miniaturized while satisfying the exhaust efficiency and the silencing characteristics.

  The present invention has been made in view of the above points, and a main object thereof is to provide a straddle-type vehicle muffler that is reduced in size while satisfying the requirements for the silencing characteristics.

  In US Pat. No. 3,263,772, a high-frequency silencing element (reference numeral 16 in FIG. 1 of the publication) is attached to a pipe (reference numeral 10 in FIG. 1) as an exhaust gas system for automobiles. Is not a resonator. Specifically, the high frequency component is silenced by air or a porous fibrous material in the cavity (reference numeral 22 in FIG. 2) of the high frequency silencing element.

  An exhaust system for a saddle-ride type vehicle according to the present invention includes an exhaust pipe connected to an engine and a silencer connected to the exhaust pipe, the exhaust pipe including a Helmholtz resonator, and The Helmholtz resonator is filled with a sound absorbing material, and the Helmholtz resonator is formed with an opening communicating with the interior of the exhaust pipe, and the opening is in the operation of the engine. It is formed in a place where the sound pressure inside the exhaust pipe is high.

  According to the present invention, the Helmholtz resonator is provided in the exhaust pipe, and the Helmholtz resonator is filled with a sound absorbing material. The level of the generated resonance frequency peak can be reduced. As a result, the silencing effect can be enhanced even when the silencer capacity cannot be increased in order to suppress the increase in the muffler weight.

1 is a side view of a motorcycle 1000 including an exhaust device 100 according to an embodiment of the present invention. It is a figure which shows the exhaust apparatus 100 which concerns on embodiment of this invention. (A) And (b) is a partially expanded view of the exhaust device 100. 3 is a diagram for explaining a Helmholtz resonator 40. FIG. (A) is a perspective view showing the exhaust pipe 20 which concerns on embodiment of this invention. (B) is sectional drawing of the exhaust pipe 20 in (a), And (c) is sectional drawing along CC line of (b). (A) is a perspective view showing the exhaust pipe 20 which concerns on embodiment of this invention. (B) is sectional drawing of the exhaust pipe 20 in (a), (c) And (d) is sectional drawing along CC line and DD line of (b). (A) is a perspective view showing the exhaust pipe 20 which concerns on embodiment of this invention. (B) is sectional drawing of the exhaust pipe 20 in (a), And (c) is sectional drawing along CC line of (b). It is a graph for demonstrating the attenuation | damping characteristic of the structure which concerns on embodiment of this invention. It is a figure showing the exhaust apparatus 100A of a comparative example. It is a perspective view showing the exhaust pipe 20 of a comparative example. It is a figure showing the exhaust apparatus 100 which concerns on embodiment of this invention. It is a perspective view showing the exhaust pipe 20 which concerns on embodiment of this invention. (A) is sectional drawing of the exhaust pipe 20 which concerns on embodiment of this invention, and (b) is sectional drawing along the BB line of (a). It is a perspective view showing the exhaust pipe 20 which concerns on embodiment of this invention. (A) is sectional drawing of the exhaust pipe 20 which concerns on embodiment of this invention, and (b) is sectional drawing along the BB line of (a). It is a perspective view showing the exhaust pipe 20 which concerns on embodiment of this invention. (A) is sectional drawing of the exhaust pipe 20 which concerns on embodiment of this invention, and (b) is sectional drawing along the BB line of (a). It is a perspective view showing the exhaust pipe 20 which concerns on embodiment of this invention. (A) is sectional drawing of the exhaust pipe 20 which concerns on embodiment of this invention, and (b) to (d) is respectively the BB line, CC line, D- of (a). It is sectional drawing along D line. It is a perspective view showing the exhaust pipe 20 which concerns on embodiment of this invention. (A) is sectional drawing of the exhaust pipe 20 which concerns on embodiment of this invention, and (b) to (d) is respectively the BB line, CC line, D- of (a). It is sectional drawing along D line. It is a perspective view showing the exhaust pipe 20 which concerns on embodiment of this invention. (A) is sectional drawing of the exhaust pipe 20 which concerns on embodiment of this invention, and (b) to (d) is respectively the BB line, CC line, D- of (a). It is sectional drawing along D line. It is a perspective view showing the exhaust pipe 20 which concerns on embodiment of this invention. (A) is sectional drawing of the exhaust pipe 20 which concerns on embodiment of this invention, and (b) to (d) is respectively the BB line, CC line, D- of (a). It is sectional drawing along D line. It is a graph for demonstrating the attenuation | damping characteristic of the structure which concerns on embodiment of this invention. It is a graph for demonstrating the attenuation | damping characteristic of the structure which concerns on embodiment of this invention. It is a graph for demonstrating the attenuation | damping characteristic of the structure which concerns on embodiment of this invention. It is a graph for demonstrating the attenuation | damping characteristic of the structure which concerns on embodiment of this invention. It is a graph for demonstrating the attenuation | damping characteristic of the structure which concerns on embodiment of this invention.

  The design of the exhaust system of a motorcycle (muffler design) was performed under various constraints, but in fact, the silencing effect could not be increased unless the volume of the silencer was increased, The phenomenon that the increase in the volume of the silencer leads to a decrease in the controllability of the motorcycle could not be avoided. For example, in the current four-cycle motocross motorcycle (especially for racing cars), the capacity of the silencer is increased, thereby satisfying both noise reduction and driving performance, so the muffler is large and heavy. Is the actual situation. Since noise is regulated, it is impossible to ignore the noise factor and make the muffler small and light.

  More specifically, due to the attenuation characteristics of the exhaust system, there are many peaks that occur due to the length of the exhaust pipe from low frequencies. In noise regulation, exhaust noise often becomes a problem due to resonance of each peak caused by the length of the exhaust pipe. As a countermeasure, the overall attenuation characteristic level has been lowered in order to lower each peak level of the exhaust pipe length. Specifically, the overall attenuation characteristic level can be lowered by enlarging the silencer body to increase the expansion ratio or performing multistage expansion. However, in the multistage expansion, the resonance of the lumped parameter system may occur at a low frequency, and conversely, the noise may be increased, and therefore the attenuation efficiency is poor. If the silencer body is enlarged to increase the expansion ratio, the maneuverability of the motorcycle is reduced.

  Under such circumstances, the inventor of the present application introduced a new technical idea to the exhaust pipe while satisfying the running performance and noise characteristics, thereby creating an exhaust system (muffler) with a small and lightweight silencer. As a result of trying to realize it and earnestly examining it, the present invention was reached.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, components having substantially the same function are denoted by the same reference numerals for the sake of brevity. In addition, this invention is not limited to the following embodiment.

  FIG. 1 shows a motorcycle 1000 equipped with an exhaust device 100 according to an embodiment of the present invention. The exhaust device 100 according to the present embodiment includes an exhaust pipe 20 connected to the engine 50 and a silencer 10 connected to the exhaust pipe 20. In the configuration example shown in FIG. 1, a tail pipe 30 is disposed at the rear end (downstream side) of the silencer 10. The tail pipe 30 is covered with a tail cap 35. For convenience, the engine 50 side may be referred to as “upstream”, and the atmosphere side (the rear end side of the silencer 10) may be referred to as “downstream”.

  When the exhaust device 100 of this embodiment is removed from the motorcycle 1000, it is as shown in FIG. The exhaust pipe 20 of the exhaust device 100 shown in FIG. 2 is provided with a protector 22 for preventing contact. FIG. 3A shows the periphery of the upstream end 20 </ b> A of the exhaust pipe 20. FIG. 3B shows the structure shown in FIG. 3A with the contact prevention protector 22 removed.

  The muffler 100 of this embodiment is a muffler for a four-cycle engine, and the motorcycle 1000 shown in FIG. 1 is an off-road vehicle. The silencer 10 is a silencer attached to the rear part of the exhaust device 100 (specifically, the rear part of the exhaust pipe 20).

  The exhaust pipe 20 of the present embodiment includes a Helmholtz resonator 40, and the Helmholtz resonator 40 is filled with a sound absorbing material. The Helmholtz resonator may be simply referred to as “resonator” or “resonator”.

A schematic diagram of the Helmholtz resonator is shown in FIG. The resonance frequency f ₀ of the Helmholtz resonator shown in FIG.

なお、ヘルムホルツ共鳴器は、首部の直径や長さ、空洞部の容積によって共振周波数の調整ができるので、用途が広いという特徴を持っている。

The Helmholtz resonator has a feature that it can be used widely because the resonance frequency can be adjusted by the diameter and length of the neck and the volume of the cavity.

  When sound near the resonance frequency enters the resonator, a large air vibration is generated by the resonance. This intense air vibration is changed to heat (friction loss) by the viscous resistance of the medium (air), and sound absorption (sound absorption, attenuation) is accompanied. Here, “resonance (or resonance)” means that vibration energy of a certain object is absorbed by another object and the object vibrates.

  When a Helmholtz resonator is installed in a pipeline (in this case, the exhaust system), although an attenuation improvement effect is obtained near the resonance frequency, a new resonance is generated by the installation, resulting in a secondary problem. Arise.

  In addition, when sound is incident on a sound absorbing material (stainless wool (SUS wool), glass wool, porous metal, etc.), air vibrations are directly transmitted to the air in the gaps and bubble portions inside the material, and the air on the surface of the fibers and bubbles The sound is absorbed by the viscous friction of the fiber, the vibration of the fiber or bubble film itself, and the like. Therefore, when the resonator is filled with a sound absorbing material, the sound absorbing effect of the resonator itself is suppressed.

  Here, in the configuration of the present embodiment, a structure that suppresses a new peak level of resonance is realized by using the point that the sound absorbing effect of the resonator itself is suppressed by the sound absorbing material. Therefore, according to the exhaust device 100 of the present embodiment, the silencing effect can be enhanced even when the capacity of the silencer cannot be increased in order to suppress an increase in the muffler weight.

  Next, the configuration and effects of the exhaust device 100 according to the embodiment of the present invention will be described with reference to FIGS. 5A to 5D.

  FIG. 5A is a diagram showing the periphery of the resonator 40 of the exhaust device 100 of the present embodiment. FIG. 5A (a) is a perspective view of the exhaust pipe 20 including the resonator 40. FIG. FIG. 5A (b) is a cross-sectional view of the exhaust pipe 20 shown in FIG. 5A (a). FIG. 5A (c) is a cross-sectional view taken along the line CC in FIG. 5A (b).

  In the exhaust device 100 shown in FIG. 5A, a Helmholtz resonator 40 is provided on the exhaust pipe 20. The Helmholtz resonator 40 is filled with a sound absorbing material (for example, SUS wool). The resonator 40 is constructed by a space formed by the outer pipe 41 located on the outer periphery of the exhaust pipe 20 and the exhaust pipe 20. In the example shown in FIG. 5A, an opening (hole) 42 communicating with the inside of the exhaust pipe 20 is formed on the upstream side (end portion 20 </ b> A side) in the resonator 40. The opening 42 is formed at a location where the sound pressure inside the exhaust pipe 20 is high during operation of the engine 50 (that is, the location of the “antinode” of the standing wave).

  Here, the location where the sound pressure inside the exhaust pipe 20 is high will be described. In terms of acoustic characteristics, the sound wave oscillates sinusoidally (pressure fluctuation) due to the dense wave of air. A predetermined resonance frequency (standing wave) is generated inside the tubular member. In view of the state of pressure fluctuation, the part of the static pressure state is referred to as a “node”, while the part in a higher state than the joint (particularly a locally high part) and the part in a low state that is the opposite phase (particularly in particular) , A locally low portion) is referred to as “belly”. In other words, a static pressure portion of a sound wave (standing wave) that vibrates sinusoidally is referred to as a “node”, and a portion where the pressure is high (and a portion in the opposite phase) is referred to as an “antinode”.

  In particular, the exhaust pipe 20 can be modeled as a tubular part having one end closed and the other end open, and the opening 42 is formed at a place where the sound pressure of the standing wave generated in the exhaust pipe is high (that is, an antinode part). Is preferably formed. By doing so, it becomes possible to intentionally reduce the predetermined frequency peak. For example, by forming the opening 42 in the exhaust pipe in at least one antinode of the third peak to the sixth peak, a predetermined peak corresponding to the opening 42 can be reduced. Since the vicinity of the end 20A of the exhaust pipe 20 often becomes a place (the antinode of the standing wave) where the sound pressure inside the exhaust pipe 20 is high, it is also preferable to form the opening 42 in that region.

  In the example shown in FIG. 5A, three openings 42 are formed on the upstream side (end portion 20 </ b> A side) in the resonator 40. In the example shown in FIG. 5B, three openings 42 are formed on the upstream side in the resonator 40, and three openings 42 are formed on the downstream side in the resonator 40.

  FIG. 5B (a) is a perspective view of the configuration of the present embodiment, and FIG. 5B (b) is a cross-sectional view of the exhaust pipe 20 including the resonator 40 shown in FIG. 5B (a). 5B (c) and 5 (d) are cross-sectional views taken along lines CC and DD in FIG. 5B (b).

Furthermore, in the example shown in FIG. 5C, six openings 42 are formed on the upstream side in the resonator 40. The relationship between the cross-sectional views of FIGS. 5C (b) and (c) is as described above with respect to the perspective view shown in FIG.

  Next, the effect of the exhaust device 100 of the present embodiment will be described with reference to FIG. 5D. FIG. 5D is a result (simulation result) of the inventors of the present invention examining the exhaust device 100. FIG. 5D is a graph showing attenuation characteristics, where the vertical axis represents the attenuation level (dB) and the horizontal axis represents the frequency (Hz).

The configuration example examined here is the example shown in FIGS. 5A to 5C (Ex. 5A, Ex. 5B, Ex. 5C). The comparative example in which the resonator 40 does not exist in the configuration shown in FIG. .1). In addition, the density (apparent density) of the SUS wool 45 with which the Helmholtz resonator 40 of each example was filled is the same. Here, the apparent density of the sound absorbing material (SUS wool) 45 refers to the density expressed by the mass (kg) of the sound absorbing material 45 filled with respect to the volume (m ³ ) of the resonator 40. For reference, in the examples shown in FIGS. 5A to 5C (Ex. 5A, Ex. 5B, Ex. 5C), a comparative example without a sound absorbing material is described in Ref. 5A, Ref. 5B, Ref. Shown as 5C.

  Although a more detailed description will be given in an embodiment to be described later, the opening 42 is formed in the exhaust pipe 20 so as to be located at a location (antinode) where the sound pressure corresponding to a predetermined frequency peak is high. . In addition, the location where the sound pressure is high (the belly location) is based on the position where the sound pressure is high in the exhaust pipe 20 before the opening 42 is formed.

  As can be understood from FIG. 5D, the attenuation level (dB) of the frequency peak to be reduced can be lowered by forming the opening 42 at a predetermined position. 5D (Ex. 5A to Ex. 5C) exhibits better attenuation characteristics than the comparative example (Ref. 1) or other comparative examples (Ref. 5A to 5C). I understand. The point of reducing the attenuation level of the frequency peak to be reduced will be further described. In the example shown in FIGS. 5A and 5C, the opening 42 is formed on the upstream side in the resonator 40, but the opening 42 is not formed on the downstream side in the resonator 40. On the other hand, in the example shown in FIG. 5B, an opening 42 is formed on the downstream side in the resonator 40. Here, referring to FIG. 5D, at frequency peak f6, Ex. It can be seen that the result of 5B can effectively reduce the attenuation level.

  Next, the configuration and effects of the exhaust device 100 according to the embodiment of the present invention will be further described with reference to FIGS.

  In the configuration shown in FIGS. 5A to 5C described above, the Helmholtz resonator 40 is designed first, and a structure in which the opening 42 is formed at a predetermined position of the exhaust pipe 20 in the region occupied by the resonator 40 is intended. On the other hand, the configuration of the embodiment described below is intended to have a structure in which the opening 42 is first formed in the exhaust pipe 20 at the location where the sound pressure is high (the belly location), and then the Helmholtz resonator 40 is formed. Thus, the effect of the present embodiment can be obtained even with such a structure.

  First, FIG. 6 is a diagram showing an exhaust device 100A (comparative example) as a basic configuration. FIG. 7 is a perspective view of the exhaust pipe 20 constituting the exhaust device 100A (comparative example). The exhaust device 100A includes an exhaust pipe 20 having an end portion 20A connected to the engine side, a catalyst storage portion 15 connected to the exhaust pipe 20, and a silencer 10 connected thereto. A tail pipe 30 is located downstream of the silencer 10.

  FIG. 8 is a view showing the exhaust device 100 of the present embodiment. In the exhaust device 100 shown in FIG. 8, a Helmholtz resonator 40 is provided in the exhaust pipe 20. The Helmholtz resonator 40 is filled with a sound absorbing material (for example, SUS wool).

  FIG. 9 is a perspective view of the exhaust pipe 20 constituting the exhaust device 100 shown in FIG. FIG. 10A is a cross-sectional view of the exhaust pipe 20 including the resonator 40 shown in FIG. In addition, FIG.10 (b) is sectional drawing along the BB line in Fig.10 (a). As described above, the resonator 40 is constructed by the space formed by the outer pipe 41 located on the outer periphery of the exhaust pipe 20 and the exhaust pipe 20.

  In the example shown in FIG. 9, an opening (hole) 42 communicating with the inside of the exhaust pipe 20 is formed on the upstream side (end portion 20 </ b> A side) in the resonator 40. The opening 42 is formed at a location where the sound pressure inside the exhaust pipe 20 is high during operation of the engine 50 (that is, the location of the “antinode” of the standing wave). As described above, the vicinity of the end portion 20A of the exhaust pipe 20 is often a place where the sound pressure inside the exhaust pipe 20 is high (standing wave antinode), so the opening 42 is formed in that region. Is preferred.

  A sound absorbing material 45 is filled in the resonator 40. The sound absorbing material 45 is a material that can absorb sound waves. For example, SUS wool (stainless steel wool), glass wool, aluminum wool, ferrite, asbestos, and the like can be used. In this example, SUS wool is used as the sound absorbing material 45. The sound absorbing material 45 absorbs high frequency sound well, but is less effective for low frequency sound. Therefore, it is preferable to design the exhaust device 100 in view of this point.

  When the Helmholtz resonator 40 shown in FIG. 9 is applied to the relationship shown in FIG. The neck cross-sectional area S is the sum of the opening areas of the through holes 42, and the neck length l is the thickness of the exhaust pipe 20. The volume V is a volume surrounded by the exhaust pipe 20 and the outer pipe 41.

  Next, a configuration example of the exhaust device 100 of the present embodiment will be described with reference to FIG. 11 and subsequent drawings.

  In the example shown in FIG. 11, an opening (hole) 42 communicating with the inside of the exhaust pipe 20 is formed in the middle flow in the resonator 40. 12 (a) is a cross-sectional view of the exhaust pipe 20 including the resonator 40 shown in FIG. 11, and FIG. 12 (b) is a cross-sectional view taken along the line BB in FIG. 12 (a). FIG.

  In the example shown in FIG. 13, an opening (hole) 42 communicating with the inside of the exhaust pipe 20 is formed on the downstream side in the resonator 40. 14A is a cross-sectional view of the exhaust pipe 20 including the resonator 40 shown in FIG. 13, and FIG. 14B is a cross-sectional view taken along line BB in FIG. 14A. FIG.

  Further, in the example shown in FIG. 15, the opening 42 is formed on the upstream side, the downstream side, and the midstream between them in the resonator 40. In other words, the resonator 40 is formed with three openings 42 communicating with the exhaust pipe 20. 16 (a) is a cross-sectional view of the exhaust pipe 20 including the resonator 40 shown in FIG. 15, and FIGS. 16 (b) to 16 (d) show the BB line in FIG. 16 (a), respectively. It is sectional drawing along a CC line and a DD line.

  Further, in the example shown in FIG. 17, two openings 42 are respectively formed on the upstream side, the downstream side, and the middle stream between them in the resonator 40. In other words, the resonator 40 is formed with six openings 42 communicating with the exhaust pipe 20. 18 (a) is a cross-sectional view of the exhaust pipe 20 including the resonator 40 shown in FIG. 17, and FIGS. 18 (b) to 18 (d) are respectively taken along line BB in FIG. 18 (a). It is sectional drawing along a CC line and a DD line.

  In the example shown in FIG. 19, the volume V of the resonator 40 in the configuration example shown in FIG. 15 is approximately doubled. 20 (a) is a cross-sectional view of the exhaust pipe 20 including the resonator 40 shown in FIG. 19, and FIGS. 20 (b) to 20 (d) are BB lines in FIG. 20 (a), respectively. It is sectional drawing along a CC line and a DD line.

  In the example shown in FIG. 21, the volume V of the resonator 40 in the configuration example shown in FIG. 17 is approximately doubled. 22 (a) is a cross-sectional view of the exhaust pipe 20 including the resonator 40 shown in FIG. 21, and FIGS. 22 (b) to 22 (d) show the BB line in FIG. 22 (a), respectively. It is sectional drawing along a CC line and a DD line.

Next, the effect of the exhaust device 100 of the present embodiment will be described with reference to FIG. FIG. 23 shows a result (simulation result) of the inventors of the present invention examining the exhaust device 100. FIG. 23 is a graph showing attenuation characteristics, where the vertical axis represents the attenuation level (dB) and the horizontal axis represents the frequency (Hz). The configuration example examined here includes the comparative example (Ref. 7) shown in FIG. 7, the example (Ex. 9) shown in FIG. 9, the example (Ex. 11) shown in FIG. It is the example (Ex. 13) shown and the example (Ex. 15) shown in FIG. In addition, the density (apparent density) of the SUS wool 45 with which the Helmholtz resonator 40 of each example was filled is the same. Here, the apparent density of the sound absorbing material (SUS wool) 45 refers to the density expressed by the mass (kg) of the sound absorbing material 45 filled with respect to the volume (m ³ ) of the resonator 40.

  Here, the upstream-side opening 42 in the resonator 40 is formed in the exhaust pipe 20 so as to be located at a portion (antinode) where the sound pressure corresponding to the peaks of the frequencies f3 and f6 in the figure is high. Yes. Further, the downstream opening 42 is formed in the exhaust pipe 20 so as to be located at a location (stomach location) where the sound pressure corresponding to the peak of the frequency f4 in the drawing is high. Then, the midstream opening 42 is formed in the exhaust pipe 20 so as to be located at a location (stomach location) where the sound pressure corresponding to the peak of the frequency f5 in the figure is high. Here, the location where the sound pressure is high (the belly location) is based on the position where the sound pressure is high in the exhaust pipe 20 before the opening 42 is formed.

  As can be understood from FIG. 23, by forming the opening 42 at a predetermined position, it is possible to reduce the attenuation level (dB) of the frequency peak to be reduced. And it turns out that the example (Ex.15) shown in FIG. 15 shows a favorable attenuation | damping characteristic compared with a comparative example (Ref.7).

  24, in addition to the results shown in FIG. 23, there are also comparative examples (Ref. 9, 11, 13, 15) in which the sound absorbing material 45 is not filled in the resonator 40 in each configuration example of the present embodiment. Show. Specifically, the comparative example without the sound absorbing material 45 in the example shown in FIG. 9 (Ref. 9), the comparative example without the sound absorbing material 45 in the example shown in FIG. 11 (Ref. 11), and shown in FIG. The results of the comparative example (Ref. 13) without the sound absorbing material 45 in the example and the comparative example (Ref. 15) without the sound absorbing material 45 in the example shown in FIG. Hereafter, the number of the comparative example without the sound absorbing material 45 (for example, Ref. 11) will be indicated by the same number as the example with the sound absorbing material 45 (for example, Ex. 11).

  As can be seen from FIG. 24, in the comparative example (Ref. 9, 11, 13, 15) in which the resonator 40 is not filled with the sound absorbing material 45, the attenuation level of the specific frequency f can be greatly reduced. New peaks occur on both sides, which worsens the attenuation characteristics.

  Reference is now made to FIG. 25 shows the attenuation characteristics of the configuration example (Ex. 17) shown in FIG. 25, in addition to the comparative example (Ref. 17) without the sound absorbing material 45 in the example shown in FIG. 7, Ex. 15 and Ref. 15 results are also shown.

  As can be seen from FIG. 25, the configuration example (Ex. 17) with six openings 42 has the same or better attenuation characteristics than the configuration example (Ex. 15) with three openings 42.

  Reference is now made to FIG. 26 shows the attenuation characteristics of the configuration example (Ex. 19) shown in FIG. 26 also shows a comparative example (Ref. 19) without the sound absorbing material 45 in the example shown in FIG. 7, Ex. 15 and Ref. 15 results are also shown.

  As can be seen from FIG. 26, the configuration example (Ex. 19) in which the volume of the resonator 40 is increased has the same or better attenuation characteristics than the other configuration example (Ex. 15). In addition, as shown in FIG. 27, the configuration example (Ex. 21) in which the volume of the resonator 40 shown in FIG. 21 is increased also has an attenuation characteristic equal to or greater than that of the other configuration example (Ex. 17). It is good. 27 also shows a comparative example (Ref. 21) without the sound absorbing material 45 in the example shown in FIG.

  According to the configuration of the present embodiment, the exhaust pipe 20 is provided with the Helmholtz resonator 40, and the Helmholtz resonator 40 is filled with the sound absorbing material 45. Therefore, while the damping characteristic is improved by the Helmholtz resonator 40 and the sound absorbing material 45 is filled in the Helmholtz resonator 40, the sound absorption effect by the Helmholtz resonator 40 is suppressed, and a new one is generated by the Helmholtz resonator 40. The level of the resonance frequency peak can be suppressed. As a result, the silencing effect can be enhanced even when the silencer capacity cannot be increased in order to suppress the increase in the muffler weight.

In FIG. 1, an off-road type motorcycle is shown as an example of the motorcycle 1000, but the motorcycle 1000 may be an on-road type. The “motorcycle” in the present specification means a motorcycle, and includes a motorbike and a scooter, and specifically refers to a vehicle that can turn by tilting the vehicle body. . Therefore, even if at least one of the front wheels and the rear wheels is two or more and the number of tires is counted as a tricycle / four-wheel vehicle (or more), it can be included in the “motorcycle”. The present invention can be applied not only to motorcycles but also to other vehicles that can utilize the effects of the present invention. For example, in addition to motorcycles, four-wheel buggy (ATV: All Terrain Vehicle)
And so-called saddle riding type vehicles including snowmobiles.

  As mentioned above, although this invention was demonstrated by suitable embodiment, such description is not a limitation matter and can be variously modified | changed naturally.

  According to the present invention, it is possible to provide a straddle-type vehicle muffler that is reduced in size while satisfying the requirements for the silencing characteristics.

DESCRIPTION OF SYMBOLS 10 Silencer 15 Catalyst accommodating part 20 Exhaust pipe 30 Tail pipe 35 Tail cap 40 Helmholtz resonator 41 Outer pipe 42 Opening part 45 Sound absorbing material 50 Engine 100 Exhaust device 1000 Motorcycle (saddle-type vehicle)

Claims (6)

An exhaust device for a saddle-ride type vehicle,
An exhaust pipe connected to the engine;
A silencer connected to the exhaust pipe,
The exhaust pipe includes a Helmholtz resonator, and the Helmholtz resonator is filled with a sound absorbing material,
The Helmholtz resonator has an opening communicating with the interior of the exhaust pipe,
The exhaust device is an exhaust device that is formed at a location where the sound pressure inside the exhaust pipe is high during operation of the engine.   2. The exhaust system according to claim 1, wherein the portion where the sound pressure is high is a position corresponding to an antinode based on a standing wave from a third peak to a sixth peak inside the exhaust pipe.   The exhaust device according to claim 1, wherein the sound absorbing material is SUS wool or glass wool.   The exhaust device according to claim 1, wherein the sound absorbing material suppresses a sound absorbing effect of the Helmholtz resonator and reduces a level of a resonance frequency peak caused by the Helmholtz resonator.   A straddle-type vehicle comprising the exhaust device according to any one of claims 1 to 4.   The saddle riding type vehicle according to claim 5, wherein the saddle riding type vehicle includes a four-cycle engine.

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