JP3026542B2 - Exhaust system for motorcycle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an exhaust system mounted on an engine of a motorcycle.

[0002]

2. Description of the Related Art A motorcycle is provided with an exhaust device for silencing exhaust of high-energy exhaust gas from an exhaust port of an engine (internal combustion engine) and discharging it to the atmosphere. As a method of reducing the energy of exhaust gas to obtain a noise reduction effect, a resistance type using friction resistance on the flow channel wall surface, an expansion type using speed reduction when flowing into the expansion chamber from the throttle section, A diffusion prevention type in which sound is absorbed by a sound absorbing member such as glass wool provided, or an interference type in which sounds having different phases in different passages interfere with each other to lower the sound pressure level are used.

[0003] The exhaust system for a motorcycle generally includes an exhaust pipe connected to an exhaust port of an engine cylinder, and a muffler (silencer) connected to a rear end of the exhaust pipe to muffle exhaust gas. , And is configured to discharge exhaust gas to the atmosphere from a rear end (for example, a tail pipe) of the muffler. In particular, in a motorcycle exhaust system connected to a multi-cylinder engine, the exhaust from each cylinder is processed in common or interferes with each other, so that the silencing is more efficient than in the case of processing individually. Various device configurations capable of performing processing have been proposed.

[0004] The structure of the exhaust system also affects the output characteristics of the engine (for example, torque-rotational speed characteristics).
In the exhaust device for a wheel, adjustment of output characteristics as well as improvement of a noise reduction effect is considered. For example, by adopting a configuration in which a plurality of exhaust pipes are merged and then introduced into a common muffler, or a configuration in which a plurality of exhaust pipes are connected to each other by a communication pipe, mutual interference of exhaust gas from cylinders having different explosion timings. A technique has been proposed which enhances the sound deadening effect without increasing the exhaust resistance by utilizing the action. Documents that disclose such prior art include, for example, Japanese Utility Model Laid-Open No.
No. 3133 (Japanese Utility Model Application No. 63-6971).

[0005]

However, in the conventional motorcycle exhaust system connected to a multi-cylinder engine, the noise reduction effect and the torque characteristic in a high engine speed region (high speed region) are not considered. Has a great improvement effect, but it is difficult to improve both the noise reduction effect and the torque characteristics in the middle and low speed range, and a configuration that can sufficiently achieve both the noise reduction function and the torque characteristics in the middle and low speed range is still realized. Not.

The present invention has been made in view of such prior art, and an object of the present invention is to easily improve both the noise reduction effect and the torque characteristic in a middle to low speed region with a simple and space-saving configuration. In addition, since the first-stage expansion chambers are connected by communication pipes, the pressure wave of one of the expansion chambers is used to promote the exhaust from the cylinder connected to the other expansion chamber, thereby improving the exhaust efficiency. It is an object of the present invention to provide a motorcycle exhaust device connected to a multi-cylinder engine.

[0007]

According to a first aspect of the present invention, there is provided an exhaust system for a motorcycle engine having a plurality of cylinders, wherein a plurality of exhaust pipes connected to each cylinder are provided. The first-stage expansion chambers are connected to the independent first-stage expansion chambers, and the first-stage expansion chambers are connected to each other via communication pipes. And the second-stage common expansion chamber is connected to a third-stage common expansion chamber via a throttle pipe, and then discharged to the outside through the throttle pipe after passing through the third-stage common expansion chamber. It is characterized by doing.

According to a second aspect of the present invention, the inside of the muffler outer cylinder is axially partitioned into three chambers, and two exhaust pipes from the two cylinders are connected to the first chamber and the second chamber. The third and third chambers and the second and third chambers are connected by respective throttle pipes, and the first and second chambers are connected by communication pipes,
By connecting a tail pipe leading to the outside to the third chamber, the exhaust pipe from each cylinder is connected to the independent first-stage expansion chamber, and each expansion chamber is connected to the second-stage expansion chamber via a throttle pipe. Wherein the first-stage expansion chambers are connected to each other by a communication pipe, and the common expansion chamber is exhausted to the outside through a throttle pipe. The above object is achieved by an apparatus.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a reference diagram showing a schematic configuration of the entire exhaust system for a motorcycle by taking a case where an engine is a single cylinder (single cylinder) as an example. In FIG. 1, an exhaust port 1 of an engine 10 is shown.
1 is connected to an exhaust pipe 12 having a predetermined length made of a steel pipe. The exhaust pipe 12 is connected to an inlet side of a muffler (muffler) 13. A tail pipe 14 for discharging to the atmosphere is provided.

According to the arrangement shown in FIG. 1, high-energy exhaust gas (exhaust gas) from the exhaust port 11 is introduced into the silencer 13 through the exhaust pipe 12, and is subjected to the above-mentioned silencing mechanism in the silencer 13. Thus, the sound pressure level of exhaust gas (exhaust gas) is effectively reduced. After being silenced to a predetermined level in this way, it is released from the tail pipe 14 to the atmosphere.

FIG. 2 shows an automatic 2 suitable for applying the present invention.
It is the schematic which shows the structure of the exhaust device for wheeled vehicles. 2, the exhaust port 2 of each cylinder 21, 21 of the two-cylinder engine 20
Exhaust pipes 23 and 23 are connected to 2 and 22, and independent first-stage expansion chambers 24 and 24 are connected to the rear ends of the exhaust pipes 23 and 23, respectively. Further, each of the expansion chambers 24, 24 is connected to a second-stage common expansion chamber 26 via respective throttle pipes 25, 25.

The outlet of the common expansion chamber 26 is a throttle pipe 27.
Through to the open air. In some cases, such as when it is desired to further enhance the noise reduction effect, as shown by a two-dot chain line, the throttle pipe 27 from the outlet of the common expansion chamber 26 may be used.
May be further connected to a common expansion chamber 28 at the third stage, and may be connected to the outside air through a throttle pipe (tail pipe) 29 connected to the outlet of the expansion chamber 28 at the third stage.

FIG. 4 is a schematic view of a first embodiment of a motorcycle exhaust system to which the present invention is applied. In this embodiment, in addition to the configuration shown in FIG. 2, the first-stage expansion chambers 24, 24 are connected to each other by a communication pipe 30. This communication pipe 30
By causing the exhaust from each cylinder to interfere with each other,
This is for canceling the wave energy of the exhaust gas to improve the sound deadening function. The first embodiment of FIG. 4 differs from the configuration of FIG. 2 in that the communication pipe 30 is provided, but has substantially the same configuration in other respects, and corresponding portions are denoted by the same reference numerals. The detailed description of is omitted.

According to the first embodiment shown in FIG.
In the exhaust device of the motorcycle engine 20 having the first and second cylinders 21 and 21, the plurality of exhaust pipes 23 and 23 connected to the respective cylinders 21 and 21 are respectively provided with independent first-stage expansion chambers 24 and 2
4 and the first-stage expansion chambers 24, 24 are connected to each other by a communication pipe 30, and the first-stage expansion chambers 24, 24 are connected to each other.
24 are connected to the second-stage common expansion chamber 26 via throttle pipes 25 and 25, respectively.
Is connected to a third-stage common expansion chamber 28 via a restriction pipe 27, and after passing through the third-stage common expansion chamber 28, the restriction pipe 2
9 so that both the noise reduction effect and the torque characteristic in the middle to low speed region can be easily improved by a simple and space-saving configuration, and each of the first-stage expansion chambers is connected by a communication pipe. Because of the connection, the pressure wave of one of the expansion chambers is used to promote the exhaust from the cylinder connected to the other expansion chamber, thereby improving the exhaust efficiency. Since the common expansion chamber of the stage is provided, the exhaust from each cylinder can be made to interfere with each other in the second expansion chamber, and then the contraction and expansion can be further repeated. An exhaust system for a vehicle is provided.

FIG. 3 shows the torque characteristics (curve A) of the engine using the exhaust system described in FIG. 2 or 4 and the torque characteristics (curve B) of the engine using the conventional exhaust system independent for each cylinder. It is a chart shown in comparison. 2 to 4
As is apparent from the above, by implementing the present invention, it is possible to obtain an exhaust device capable of easily improving torque characteristics in a middle to low speed region with a simple and space-saving configuration. Further, according to the present invention, the noise reduction effect in the middle to low speed region can be significantly improved. Further, according to the first embodiment of FIG. 4, since the first-stage expansion chambers are connected by the communication pipe, the exhaust from the cylinder connected to the other expansion chamber using the pressure wave of one expansion chamber. And the third stage common expansion chamber is provided after the second stage common expansion chamber, so that exhaust from each cylinder interferes with each other in the second expansion chamber. After joining, the contraction and expansion can be further repeated, and the decompression and silencing can be efficiently performed.

Although the configuration of FIG. 2 and the first embodiment of FIG. 4 illustrate the case where the present invention is applied to a two-cylinder engine, the present invention is applicable to a multi-cylinder engine having three or more cylinders. The same operation and effect can be obtained for each cylinder or for each group of more cylinders.

FIG. 5 is a longitudinal sectional view showing a specific example of a structure suitable for implementing the exhaust device of FIG. 2, and FIG. 6 is a sectional view taken along line 6-6 in FIG. 7 is a line 7- in FIG.
FIG. 7 is an end view seen from 7. In FIG. 5 to FIG. 7, the inside of a muffler outer cylinder 35 formed of an airtight cylindrical container having a predetermined length is divided into three chambers 38, 39, and 40 in the axial direction (length direction) by baffle plates (partition walls) 36 and 37. The rear end of one (first) exhaust pipe 23A of the exhaust pipes from the two cylinders 21 and 21 is connected to the first chamber 38, and the other end of the other (second) exhaust pipe 23B. The rear end is the second room 3
9. The first chamber 38 and the second chamber 39 constitute the first-stage expansion chambers 24, 24 in FIG.

The first chamber 38 and the third chamber 40 are connected by a pipe 41, and the second chamber 39 and the third chamber 40 are connected by a pipe 42. These pipes 41 and 42 constitute the throttle pipes 25 and 25 in FIG. 2, and the third chamber 40 constitutes the common expansion chamber 26 in the second stage in FIG. Further, the third chamber 40 communicates with the outside air through a pipe 43 fixed to the rear end. This pipe 43 constitutes the throttle pipe (tail pipe) 27 in FIG. In the illustrated example, the tail pipe 43 is attached with a sound absorbing material 45 interposed. If necessary, a sound absorbing material layer may be joined to the inner surface of the muffler outer cylinder 35.

FIG. 8 is a longitudinal sectional view showing a specific example of a structure suitable for implementing the exhaust device of FIG. 4, and FIG. 9 is a sectional view taken along line 9-9 in FIG. 10 is line 1 in FIG.
It is the end elevation seen from 0-10. 8 to 10 provide an exhaust system for a motorcycle according to a second embodiment of the present invention. In this embodiment, in addition to the configuration shown in FIGS. 5 to 7, a pipe 4 is provided between the first chamber 38 and the second chamber 39.
4. The communication pipe 3 connects the first-stage expansion chambers 24, 24 shown in FIG.
0, which is to improve the noise reduction function by canceling out the wave energy of the exhaust by causing the exhaust from each of the cylinders 21 and 21 to interfere with each other.

The exhaust system according to the second embodiment shown in FIGS. 8 to 10 is different from the exhaust system shown in FIGS. 5 to 7 in that the first chamber 38 and the second chamber 39 are communicated by a pipe 44. In other respects, they have substantially the same configuration. Corresponding portions are denoted by the same reference numerals, and detailed description thereof will be omitted.

According to the exhaust system for a motorcycle according to the second embodiment described with reference to FIGS. 8 to 10, the inside of the muffler outer cylinder 35 is divided into three chambers 38, 39, and 40 in the axial direction. The two exhaust pipes 23A and 23B from the cylinder are connected to the first chamber 38.
Is connected to the second chamber 39, the first chamber 38 and the third chamber 40, and the second chamber 39 and the third chamber 40 are connected by the throttle pipes 41 and 42, respectively. By connecting the second chamber 39 with a communication pipe 44 and connecting the third chamber 40 with a tail pipe 43 leading to the outside, FIG.
Exhaust pipes 23, 2 from each cylinder 21, 21 as shown in FIG.
3 are connected to independent first-stage expansion chambers 24, 24, respectively.
It is connected to a common expansion chamber 26 of the first stage, the expansion chambers 24, 24 of the first stage are connected to each other by a communication pipe 30, and the common expansion chamber 26 is evacuated to the outside through a restrictor 27. An exhaust device for a motorcycle is provided.

According to the present invention according to the second embodiment shown in FIGS. 8 to 10, both the noise reduction effect and the torque characteristic in the middle to low speed range can be easily improved by a simple and space-saving structure. Since each of the expansion chambers of the stage is connected by the communication pipe, the pressure wave of one of the expansion chambers is used to promote the exhaust from the cylinder connected to the other expansion chamber, thereby improving the exhaust efficiency. 2 using the inside of one muffler
Since the exhaust system silencer of the present invention can be configured, an exhaust system for a motorcycle that can further save space can be obtained.

5 to 7 and FIGS. 8 to 10
According to the configuration described above, both the silencing effect and the torque characteristic in the middle and low speed range as described in the chart of FIG. 3 are connected to a multi-cylinder engine that can be easily improved with a simple and space-saving configuration. A motorcycle exhaust device is provided. In addition, in the configuration of FIGS.
Similarly, the throttle pipe 43 from the outlet of the common expansion chamber 40 is further connected to the third-stage common expansion chamber (2 in FIG. 4).
8), and may be configured to communicate with the outside air through a throttle pipe (tail pipe) connected to the outlet of the third-stage expansion chamber. Further, the configurations of FIGS. 5 to 7 and FIGS.
In the configuration of No. 0, the case where the present invention is applied to a two-cylinder engine has been exemplified. However, even in a multi-cylinder engine of three or more cylinders, these configurations may be used for each group of two or more cylinders. Can be implemented as well,
A similar effect can be obtained. Further, the present invention can be similarly applied to a three- or four-wheeled vehicle having an engine similar to that of a two-wheeled vehicle, and can achieve the same effect.

[0024]

As is apparent from the above description, according to the first aspect of the present invention, in the exhaust system for a motorcycle engine having a plurality of cylinders, a plurality of exhaust pipes connected to each cylinder are provided. The first-stage expansion chambers are connected to the independent first-stage expansion chambers, and the first-stage expansion chambers are connected to each other via communication pipes. And the second-stage common expansion chamber is connected to a third-stage common expansion chamber via a throttle pipe, and then discharged to the outside through the throttle pipe after passing through the third-stage common expansion chamber. Because it is configured to perform both, the noise reduction effect and the torque characteristic in the middle and low speed region can be easily improved by a simple and space-saving configuration, and since the first-stage expansion chambers are connected by the communication pipe, Connected to the other expansion chamber using the pressure wave of one expansion chamber Exhaust from the cylinders is promoted to improve the exhaust efficiency, and the third-stage common expansion chamber is further provided after the second-stage common expansion chamber. Thus, an exhaust system for a motorcycle is provided which can repeat contraction and expansion after interference with each other, and can efficiently reduce pressure and mute.

According to the invention of claim 2, the inside of the muffler outer cylinder is axially partitioned into three chambers, and two exhaust pipes from the two cylinders are connected to the first chamber and the second chamber, The first chamber and the third chamber, and the second chamber and the third chamber are each connected by a restrictor, the first chamber and the second chamber are connected by a communication pipe, and the third chamber is connected to the outside. By connecting the tail pipes that communicate with each other, the exhaust pipes from each cylinder are connected to independent first-stage expansion chambers, and each expansion chamber is connected to the second expansion chamber via a throttle pipe.
An exhaust system for a motorcycle which is connected to a common expansion chamber of the first stage, connects each of the expansion chambers of the first stage to each other through a communication pipe, and exhausts the common expansion chamber to the outside through a throttle pipe. Therefore, both the noise reduction effect and the torque characteristic in the middle and low speed range can be easily improved with a simple and space-saving configuration. Using the pressure wave of the expansion chamber, the exhaust from the cylinder connected to the other expansion chamber can be promoted to increase the exhaust efficiency, and furthermore, the muffler of two exhaust systems can be silenced using the inside of one muffler. There is provided an exhaust system for a motorcycle, which is capable of constructing the device and thereby further saving space.

[Brief description of the drawings]

FIG. 1 is a reference diagram showing a schematic configuration of an entire motorcycle exhaust system, taking a case where an engine is a single cylinder as an example.

FIG. 2 is a schematic diagram showing a configuration of a motorcycle exhaust device suitable for applying the present invention.

FIG. 3 is a table showing the torque characteristics of an engine using the configuration of FIG. 2 or the exhaust device according to the present invention in comparison with a conventional example.

FIG. 4 shows a first example of a motorcycle exhaust system to which the present invention is applied.
It is the schematic of an Example.

FIG. 5 is a longitudinal sectional view showing a specific example of a structure suitable for implementing the exhaust device of FIG. 2;

FIG. 6 is a sectional view taken along lines 6-6 in FIG. 5;

FIG. 7 is an end view taken along line 7-7 in FIG. 5;

FIG. 8 is a longitudinal sectional view showing a specific structural example (second embodiment) suitable for implementing the exhaust device of FIG. 4;

FIG. 9 is a cross-sectional view taken along line 9-9 in FIG.

FIG. 10 is an end view taken along line 10-10 in FIG. 8;

[Explanation of symbols]

 Reference Signs List 20 engine 21 cylinder 23 exhaust pipe 24 first-stage expansion chamber 25 throttle pipe 26 second-stage common expansion chamber 27 throttle pipe 28 third-stage common expansion chamber 29 throttle pipe (tail pipe) 30 communication pipe 35 muffler Outer cylinder 36 Partition wall 37 Partition wall 38 First chamber 39 Second chamber 40 Third chamber 41 Restrictor pipe 42 Restrictor pipe 43 Restrictor pipe 44 Communication pipe

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-66722 (JP, A) JP-A 62-66214 (JP, U) JP-A 4-134624 (JP, U) JP-A 63-662 143713 (JP, U) Japanese Utility Model Showa 60-128921 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01N 1/08 F01N 1/06 F01N 1/24 F01N 7/04

Claims (2)

(57) [Claims] In an exhaust system for a motorcycle engine having a plurality of cylinders, a plurality of exhaust pipes connected to each cylinder are connected to independent first-stage expansion chambers, respectively, and the first-stage expansion chamber is connected to each of the first-stage expansion chambers. Each expansion chamber is connected to each other by a communication pipe, the first-stage expansion chamber is connected to a second-stage common expansion chamber via a throttle pipe, and the second-stage common expansion chamber is connected to a throttle pipe. An exhaust system for a motorcycle, characterized in that the exhaust system is connected to a third-stage common expansion chamber through the third-stage common expansion chamber, and then discharged outside through a throttle pipe after passing through the third-stage common expansion chamber. 2. The interior of the muffler outer cylinder is axially partitioned into three chambers, two exhaust pipes from the two cylinders are connected to the first chamber and the second chamber, and the first chamber and the third chamber are connected. Room and 2
The third and third chambers are connected by a throttle pipe, the first and the second chambers are connected by a communication pipe, and the third chamber is connected by a tail pipe leading to the outside. Are connected to independent first-stage expansion chambers, each expansion chamber is connected to a second-stage common expansion chamber via a throttle pipe, and the first-stage expansion chambers are connected to each other. An exhaust system for a motorcycle, wherein the exhaust system is connected by a pipe and exhausted from the common expansion chamber to the outside through a throttle pipe.