This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2017-167698, filed on Aug. 31, 2017, the entire contents of which are incorporated herein by reference.
The present invention typically relates to an air exhausting device coupled to an engine of a motorcycle.
Conventionally, for example, a muffler disclosed in Patent Document 1 includes a pipe-shaped muffler shell, an inlet pipe that introduces an exhaust gas into this muffler shell, and an outlet pipe that discharges the exhaust gas inside this muffler shell to the outside. The inlet pipe is inserted into this muffler shell from an end plate at one end of the muffler shell, and the outlet pipe is derived from an end plate at another end.
The conventional example as described above ensures silencing effect from a low-frequency range to a high-frequency range. However, it is substantially difficult to ensure reduction in exhaust gas pressure. Therefore, it is actually impossible to ensure the silencing effect and improvement in engine output at the same time.
To solve the actual conditions, an object of the present invention is to provide an air exhausting device that effectively ensures improvement in engine output and silencing effect at the same time.
An air exhausting device of the present invention includes an inlet pipe that couples an exhaust pipe of an engine to a muffler, an outlet pipe that is a path to discharge an exhaust gas inside the muffler to outside air, and the muffler divided into a plurality of chambers by a separator. The muffler is configured of a first expansion chamber, a second expansion chamber with which the outlet pipe is communicated, and a third expansion chamber. The inlet pipe is communicated with the first expansion chamber. The outlet pipe is communicated with the second expansion chamber. The first expansion chamber is adjacent to and communicated with the second expansion chamber via a first pipe. The second expansion chamber is communicated with the third expansion chamber via a second pipe. The first expansion chamber is communicated with the third expansion chamber via a third pipe.
The following describes preferred embodiments of an air exhausting device according to the present invention based on the drawings. An air exhausting device built into an engine of a motorcycle is exemplified as an application example of the present invention.
An air exhausting device according to one embodiment of the present invention includes an inlet pipe that couples an exhaust pipe of an engine to a muffler, an outlet pipe that is a path to discharge an exhaust gas inside the muffler to outside air, and the muffler divided into a plurality of chambers by a separator. The muffler is configured of a first expansion chamber, a second expansion chamber with which the outlet pipe is communicated, and a third expansion chamber. The inlet pipe is communicated with the first expansion chamber. The outlet pipe is communicated with the second expansion chamber. The first expansion chamber is adjacent to and communicated with the second expansion chamber via a first pipe. The second expansion chamber is communicated with the third expansion chamber via a second pipe. The first expansion chamber is communicated with the third expansion chamber via a third pipe.
In the air exhausting device of the present invention, in combination of two exhaust paths having different path lengths ensures an effect of reduction in exhaust gas pressure and an effect of reduction in exhaust noise at the same time.
Including
The motorcycle including the air exhausting device 10 in the first embodiment forms a framework of vehicle body with a vehicle body frame made of steel or of aluminum alloy. In
The engine 1 includes an air intake system where air purified by an air cleaner (not illustrated) is supplied to the engine 1 via an intake passage. In this case, a mixture at a predetermined mixing ratio formed of air and fuel is supplied from a throttle body arranged on the middle of the intake passage to an intake port (not illustrated) disposed on a back portion of the cylinder head 4. A combustion gas that has exploded and combusted inside the cylinder block 3 of the engine 1 in an exhaust system is discharged from the engine 1. That is, the combustion gas generated inside the engine 1, as an exhaust gas, passes through an exhaust pipe 6 coupled to an exhaust port (not illustrated) of the engine 1. Then, the combustion gas is discharged to the outside air from the air exhausting device 10 coupled to the exhaust pipe 6.
Next,
In this embodiment, the muffler 11 is divided into a plurality of chambers by separators 14 and 15.
The muffler 11 is divided by the separators 14 and 15 to be configured of a first expansion chamber 16, a second expansion chamber 17, and a third expansion chamber 18. The outlet pipe 13 is communicated with the second expansion chamber 17.
In this case, the inlet pipe 12 is communicated with the first expansion chamber 16. The outlet pipe 13 is communicated with the second expansion chamber 17.
In this embodiment, especially, the first expansion chamber 16 is adjacent to and communicated with the second expansion chamber 17 via a first pipe 19.
The second expansion chamber 17 is communicated with the third expansion chamber 18 via a second pipe 20.
The first expansion chamber 16 is communicated with the third expansion chamber 18 via a third pipe 21.
With reference to
A part of the exhaust gas that has flowed into the first expansion chamber 16 flows into the third expansion chamber 18 via the third pipe 21 as an arrow g1, along an exhaust path 23 indicated by the dotted line in
In the first embodiment, the exhaust gas discharged from the engine 1 flows into the first expansion chamber 16 from the exhaust pipe 6 via the inlet pipe 12. Then, the exhaust gas branches off to the exhaust path 22 and to the exhaust path 23. Both are finally discharged to the outside air from the air exhausting device 10. The exhaust path 22 has a path length shorter than a path length of the exhaust path 23. An exhaust path 22 side contributes to reduction in exhaust gas pressure. On the other hand, an exhaust path 23 side whose path length is long contributes to reduction in exhaust noise. Such a combination of the two exhaust path 22 and exhaust path 23 having different path lengths, that is, a separate disposition of the exhaust path 22 having an effect of the reduction in exhaust gas pressure and the exhaust path 23 having an effect of the reduction in exhaust noise ensures effects of the reduction in the exhaust gas pressure (increase in engine output) and the reduction in exhaust noise at the same time in the muffler 11.
In the above-described case, adjusting diameters and lengths of the respective pipes ensures reduction in sound of a wavelength that is a target.
It is estimated that the exhaust noise is reduced such that a phase difference occurs in sound waves passing through different exhaust paths.
It is also estimated that the effect of the reduction in exhaust noise is ensured such that energy of the exhaust noise attenuates by occurrence of a difference in air pressure between inside the respective pipes and inside the respective expansion chambers and reflected sound inside the expansion chamber.
Further, in a cross-sectional view of the muffler 11, as the respective pipes in the respective expansion chambers are arranged more adjacent to one another, the exhaust gas preferentially flows.
Similarly, in the cross-sectional view, as a difference in amounts of projection between end parts of the respective pipes in the respective expansion chambers is small, the exhaust gas preferentially flows.
The following describes a second embodiment of the air exhausting device 10 according to the present invention.
In the second embodiment, in a cross section along a longitudinal direction of the muffler 11, the first pipe 19 is adjacent to the second pipe 20 such that their distal ends overlap one another in the longitudinal direction inside the second expansion chamber 17 (an area A indicated by the dotted line in
With reference to
A part of the exhaust gas that has flowed into the first expansion chamber 16 flows into the third expansion chamber 18 via the third pipe 21 as an arrow g1. Then, this exhaust gas flows into the second pipe 20 (an arrow g2) to flow into the second expansion chamber 17 via the second pipe 20 (an arrow g3). Further, this exhaust gas flows into the outlet pipe 13 (an arrow g4) to be discharged from the air exhausting device 10 through the outlet pipe 13 to the outside air (an arrow g5).
In the second embodiment, the first pipe 19 is adjacent to the second pipe 20 such that their distal ends overlap one another in the longitudinal direction. Thus, the exhaust gas that has passed through the first pipe 19 whose flow rate is fast collides with the separator 15 to prevent the flow into the third expansion chamber 18. This ensures a muffler structure that centers on the reduction in exhaust gas pressure.
The following describes a third embodiment of the air exhausting device 10 according to the present invention.
In the third embodiment, in a cross section along a longitudinal direction of the muffler 11, the first pipe 19 and the second pipe 20 are arranged at positions where their distal ends are approximately faced to one another in the longitudinal direction inside the second expansion chamber 17 (an area A indicated by the dotted line in
With reference to
A part of the exhaust gas that has flowed into the first expansion chamber 16 flows into the third expansion chamber 18 via the third pipe 21 as an arrow g1. Then, this exhaust gas flows into the second pipe 20 (an arrow g2) to flow into the second expansion chamber 17 via the second pipe 20 (an arrow g3). Further, this exhaust gas flows into the outlet pipe 13 (an arrow g4) to be discharged from the air exhausting device 10 through the outlet pipe 13 to the outside air (an arrow g5).
In the third embodiment, the first pipe 19 and the second pipe 20 are arranged at the positions where their distal ends are approximately faced to one another in the longitudinal direction. Thus, the exhaust gas that has passed through the first pipe 19 whose flow rate is fast collides with the exhaust air that has passed through the second pipe 20 whose flow rate is slow to flow into the third expansion chamber 18. This ensures a muffler structure that centers on the reduction in exhaust noise.
The following describes a fourth embodiment of the air exhausting device 10 according to the present invention.
In the fourth embodiment, in a cross section along a longitudinal direction of the muffler 11, the second pipe 20 and the outlet pipe 13 are arranged at positions where their distal ends are approximately faced to one another in the longitudinal direction inside the second expansion chamber 17 (an area A indicated by the dotted line in
With reference to
A part of the exhaust gas that has flowed into the first expansion chamber 16 flows into the third expansion chamber 18 via the third pipe 21 as an arrow g1. Then, this exhaust gas flows into the second pipe 20 (an arrow g2) to flow into the second expansion chamber 17 via the second pipe 20 (an arrow g3). Further, this exhaust gas flows into the outlet pipe 13 (an arrow g4) to be discharged from the air exhausting device 10 through the outlet pipe 13 to the outside air (an arrow g5).
In the fourth embodiment, the second pipe 20 and the outlet pipe 13 are arranged at the positions where their distal ends are approximately faced to one another in the longitudinal direction. Thus, the exhaust gas easily flows into the outlet pipe 13 from the second pipe 20. This ensures a muffler structure that centers on the reduction in exhaust gas pressure.
The following describes a fifth embodiment of the air exhausting device 10 according to the present invention.
In the fifth embodiment, in a cross section along a longitudinal direction of the muffler 11, the inlet pipe 12 is adjacent to and between the third pipe 21 and the outlet pipe 13.
In this case, a difference d1 in amounts of projection from the separator 14 of respective end portions of the third pipe 21 and the inlet pipe 12 inside the first expansion chamber 16 is set smaller than a difference d2 in amounts of projection from the separator 14 of respective end portions of the first pipe 19 and the inlet pipe 12 inside the first expansion chamber 16.
With reference to
A part of the exhaust gas that has flowed into the first expansion chamber 16 flows into the third expansion chamber 18 via the third pipe 21 as an arrow g1. Then, this exhaust gas flows into the second pipe 20 (an arrow g2) to flow into the second expansion chamber 17 via the second pipe 20 (an arrow g3). Further, this exhaust gas flows into the outlet pipe 13 (an arrow g4) to be discharged from the air exhausting device 10 through the outlet pipe 13 to the outside air (an arrow g5).
In the fifth embodiment, the difference d1 in the amounts of projection of the third pipe 21 and the inlet pipe 12 is set smaller than the difference d2 in the amounts of projection of the first pipe 19 and the inlet pipe 12. At the end portions of the first pipe 19 and the third pipe 21 that are adjacent to the inlet pipe 12, as it is closer to the end portion of the inlet pipe 12 into which the exhaust gas flows, that is, with respect to a third pipe 21 side, the exhaust gas further easily flows. This ensures a muffler structure that centers on the reduction in exhaust noise in combination with the reduction in exhaust gas pressure.
Here, in deformation of the present invention, between the adjacent expansion chambers may be coupled by holes formed on the separators 14 and 15 not the pipes (the first pipe 19, the second pipe 20, and the third pipe 21). In this case, although the effect of the reduction in the exhaust gas pressure is obtained, the effect of the reduction in exhaust noise slightly decreases.
While the present invention has been described using various embodiments above, the present invention is not limited only to these embodiments. Changes and similar modification are possible within the scope of the present invention.
The present invention functions as an air exhausting device with respect to an engine mounted on another vehicle and the like similarly to the above description, not limited to the engine mounted on the motorcycle.
With the present invention, effects of reduction in exhaust gas pressure (increase in engine output) and reduction in exhaust noise are ensured at the same time.
Number | Date | Country | Kind |
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2017-167698 | Aug 2017 | JP | national |