JP3549796B2 - Muffler tail pipe structure - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a muffler (muffler) for a vehicle such as a motorcycle or a four-wheeled vehicle, and more particularly, to a structure of a tail pipe portion thereof.
[0002]
[Prior art]
For example, in a muffler for a motorcycle, the structure of the tail pipe portion is such that a straight tubular tail pipe 14 extends outward (rearward) from a rear portion of the muffler body 11, as schematically shown in FIG. A tail pipe 14 is surrounded by a large-diameter dummy pipe (also called a decorative pipe) 13. Similarly, the periphery of the muffler body 11 is also surrounded by a dummy muffler cover body 12, and the dummy pipe 13 is integrally connected to a rear end of the muffler cover body 12. In the case of a motorcycle, such a structure is exhibited because the muffler is mounted on the outside of the vehicle body, so that the dummy pipe 13 and the muffler cover body 12 are usually made of aluminum to improve the appearance. This is because it is necessary to be formed of a good-looking metal material such as an alloy or stainless steel. That is, the tail pipe 14 of the muffler body 12 is designed to surround the periphery of the tail pipe 14 with the dummy pipe 13, and the outlet end of the tail pipe 14 does not project from the opening end of the dummy pipe 13.
[0003]
A prior art of a muffler having the same structure as that described above is disclosed in Japanese Utility Model Publication No. 2-18260.
[0004]
[Problems to be solved by the invention]
The conventional muffler having the structure of the tail pipe portion has room for improvement in the following points.
[0005]
That is, when decelerating the vehicle while repeatedly accelerating and decelerating during operation of the engine, an unpleasant noise such as a humle may be generated from near the end of the tail pipe outlet, which is annoying to the driver. The phenomenon is that when the engine accelerates, the exhaust gas increases and the pressure inside the muffler increases, so the exhaust gas flows only outward from the tail pipe, but the amount of exhaust gas decreases when the engine decelerates. Exhaust gas is discharged or sucked from the tail pipe due to the influence of exhaust pulsation or the like. That is, it is considered that exhaust gas enters and exits near the end of the tail pipe outlet, and a so-called whistling phenomenon occurs. In particular, in the muffler having the dummy pipe around the tail pipe as described above, the exhaust gas is caught in the annular space (gap) between the tail pipe and the dummy pipe, so that the Hull-Hull sound is more easily generated.
[0006]
The present invention has been made in view of the above points, and by preventing the above-described Hühlühl noise from being generated, by improving the end of the tailpipe outlet so that the flow of exhaust gas becomes favorable, and In particular, when applied to a motorcycle (motorcycle), the purpose is to improve the appearance in appearance. In other words, the present invention provides a structure of a tailpipe portion of a muffler that does not generate a humming sound when the engine is decelerated and is excellent in design.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a tailpipe portion structure of a muffler according to the present invention includes a tailpipe at a rear end of the muffler, and a straight outer pipe having a slightly larger diameter on a rear outer peripheral surface of a straight pipe body. Are sequentially and stepwisely covered so as to protrude by a slight length from the rear end of the pipe main body in a stepwise manner, and the inner diameter of the tail pipe outlet end is gradually increased. And The inner diameter of the end of the outlet is gradually expanded to specifically mean that a pipe having a larger diameter is projected to the end of the outlet by a small length in a double or triple stepwise manner. The case where the diameter is increased by successively covering the diameters.
[0008]
According to the tailpipe structure having the above configuration, even if acceleration and deceleration are repeatedly performed during operation of the engine, exhaust gas flows from the tailpipe outlet end while flowing into the muffler body from the engine and being muffled. When the exhaust gas is discharged or when the exhaust gas is sucked from the outside into the tail pipe, the flow of the exhaust gas becomes smooth, so that the Hull-Hull sound which has conventionally occurred is not generated.
[0009]
In the tail pipe portion structure of claim 1, it is sufficient to form a triple tube to covered state a large straight tubular outer pipe slightly caliber on the outer peripheral surface of the straight tubular pipe, on top manufacture simple , to the extent that it is also confirmed that the step portion of the triple tube peek the muffler of the tail pipe from the rear, because appears to be composed of a single pipe, appearance is simple, also clean in design I have. On the other hand, if the end of the tail pipe outlet is tapered (cone-shaped) or trumpet-shaped, the processing becomes complicated, and when the tail pipe of the muffler is viewed from behind, Since the end of the outlet feels thick, the design is not good.
[0010]
As described in claim 2, it is preferable that the inclination angle of the enlarged diameter portion at the rear end of the tail pipe is approximately 45 ° to 65 °.
[0011]
According to the tail pipe structure of the second aspect, the degree of expansion from the end of the pipe main body to the end of the outer pipe (inclination angle α: see FIG. 1B) is in a relatively gentle range of about 45 ° to 65 °. Exhaust gas flows smoothly because it is suppressed.
[0012]
According to a third aspect of the present invention, a large-diameter dummy pipe surrounding the periphery of the tail pipe is provided by blackening the tail pipe, and an outlet end of the tail pipe coincides with or is withdrawn from the dummy pipe. Position can be set.
[0013]
According to the tail pipe structure of the third aspect , the dummy pipe is generally formed of a good-looking metal material, which is called a decorative pipe, and the black tail pipe is disposed in the dummy pipe. So inconspicuous. Therefore, it is most suitable for disposing the muffler entirely outside the vehicle body like a motorcycle (motorcycle).
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a tailpipe structure of a muffler according to the present invention will be described with reference to the drawings.
[0015]
FIG. 1A is a cross-sectional view showing an outline of the entire structure showing a reference example of a muffler, and FIG. 1B is an enlarged cross-sectional view showing a tail pipe portion of the muffler of FIG. 1A. As shown in FIG. 1 (a), the muffler 1 has a cylindrical shape, a rear end face 1C is narrowed down toward a central exhaust port 1B, and a large-diameter dummy pipe 1A is integrally connected to the exhaust port 1B. Has been extended to. The inside of the main body 1 'of the muffler 1 is partitioned by two partition walls 2.3 arranged at intervals in the axial direction, and divided into three chambers of a front chamber 1c, an intermediate chamber 1d, and a rear chamber 1e. An exhaust pipe 4 is connected to the center of the front surface of the muffler 1, the front chamber 1c and the rear chamber 1e are connected by a communication pipe 5 penetrating the partition walls 2.3, and the rear chamber 1e and the intermediate chamber 1d form the partition wall 3. They are connected by a penetrating communication pipe 6. A tail pipe 7 is provided so as to extend from the intermediate chamber 1d to the center of the rear chamber 1e. The tail pipe 7 passes through the center of the partition wall 3, the center of the rear wall 8, and the exhaust port 1B. The dummy pipe 1A extends to the vicinity of the outlet end of the dummy pipe 1A.
[0016]
As shown in FIG. 1B, the tail pipe 7 has a double pipe structure in which a straight outer pipe 7b having a slightly larger diameter is provided on the outer peripheral surface of the rear part of the straight pipe body 7a. The open end of the pipe 7b protrudes from the open end (discharge end) of the pipe body 7a. In the present example, the thickness (t) of the pipe body 7a and the thickness (t) of the outer pipe 7b are each equal to 1 mm, and the amount of protrusion (length) of the open end of the outer pipe 7b from the open end of the pipe body 7a is , About 1.2 mm, which is almost equal to the thickness (t).
[0017]
The muffler 1 of this embodiment is constructed as described above. The muffler 1 of this embodiment is for a motorcycle, and the muffler 1 has a double structure, and as shown in FIG. An iron muffler main body 1 'is inserted into the portion 1 ". The dummy pipe 1A is also made of an aluminum alloy, and is integrally connected to (the exhaust port 1B of) the muffler exterior portion 1". On the other hand, the tail pipe 7 and the muffler main body 1 ′ are made of a metal material having excellent heat resistance (in this example, made of iron) because the high-temperature exhaust gas comes into direct contact therewith, and are black-baked. Although not shown, the inner peripheral surface of the muffler main body 1 'is covered with a heat insulating material such as glass wool and then covered with a perforated plate such as a punching plate. Although not shown, the communication pipes 5 and 6 are similarly covered with a perforated plate after a heat insulating material is wound around the inner peripheral surface. FIG. 2 is a perspective view showing the entire appearance of the muffler 1 as viewed from the rear side, and a bracket 9 to be attached to a motorcycle body is fixed by welding.
[0018]
The muffler 1 of the present embodiment has the above-described configuration, and exhaust gas from an engine (not shown) flows from an exhaust pipe 4 into a front chamber 1c in the muffler 1, and as shown in FIG. After sequentially flowing into the intermediate chamber 1d and being silenced, it is discharged from the tail pipe 7 to the outside. The exhaust gas from the tail pipe 7 flows out smoothly so as to spread outward from the step at the end of the outlet as shown in FIG. Further, when the engine is decelerated, the exhaust gas once discharged from the tail pipe 7 may be sucked into the tail pipe 7, but smoothly flows through the step portion at the end of the tail pipe 7, and the conventional exhaust gas may be exhausted. On the contrary, the exhaust gas does not get caught in the annular space between the tail pipe 7 and the dummy pipe 1A. For this reason, even if the engine is repeatedly accelerated and decelerated, no humming noise is generated.
[0019]
FIG. 3 is a partial sectional view showing a tail pipe portion according to the embodiment of the present invention, and corresponds to FIG.
[0020]
As shown in FIG. 3, the discharge port end 7c of the tail pipe 7 'of this example is bent and formed in a trumpet shape so that the diameter gradually increases outward. The remaining configuration is the same as that of the first embodiment, such as a dummy pipe 1A provided around the rear portion of the tail pipe 7 '. Therefore, common members are shown and described using the same reference numerals. Is omitted. The outlet end portion 7c in the form of a trumpet is formed by pressing or the like. For example, the outlet end portion 7c is formed in a triple pipe structure, and the inner peripheral surface side is gradually tapered outward or gradually expanded by cutting. It may be formed in a shape. The length p of the outlet end 7c is the same (t) to about 3 times (3t) as the thickness (t) of the tail pipe 7 ', and the inclination angle β of the enlarged diameter bent portion is 45 ° or more. It may be set to about 65 °.
[0021]
Although the embodiment of the tail pipe portion structure of the present invention has been described above, the present invention can be implemented as follows.
[0022]
a) Around the end of the outlet of the tail pipe 7, a plurality of (three or more) pipes are superimposed in a double tube, and are arranged so as to project stepwise from the inside to the outside of the outlet.
[0023]
b) The rear part of the tail pipe 7 is exposed to the rear of the muffler by omitting the dummy pipe 1A and the exterior part 1 ″ around the tail pipe 7. In this case, too, the exhaust gas does not get caught in the gap with the dummy pipe 1A. As a result, the effect of preventing the generation of the sound of the sound is improved.
[0024]
c) The structure inside the muffler body 1 'is not limited to the structure shown in FIG. 1A, but various structures are applied.
[0025]
d) In the tail pipe structure of the first embodiment, the protrusion amount s (FIG. 1B) of the open end of the outer pipe 7b from the open end of the pipe body 7a is set to about 1.2 mm. It is not limited to. That is, the protrusion amount s is preferably the same (t) to about twice (2t) as the thickness t of the pipe body 7a. However, strictly speaking, the flow of exhaust gas changes depending on the structure inside the muffler body 1 '. It is better to determine the optimum protrusion amount s. Further, the length p and the inclination angle β of the outlet end portion 7c of the tail pipe 7 'of the second embodiment can be tested to determine the optimum numerical values.
[0026]
【The invention's effect】
As is apparent from the above description, the tail pipe structure of the present invention has the following effects.
[0027]
(1) According to the first aspect of the invention, since the flow of the exhaust gas at the tail pipe, particularly at the end of the exhaust port, becomes smooth, the exhaust gas from the engine is exhausted even if acceleration and deceleration are repeated during operation of the engine. After flowing into the main body, when the exhaust gas is exhausted from the end of the tail pipe or when the exhaust gas is sucked into the tail pipe from the outside, the conventional noise does not occur.
Further, Runode be slightly formed by sequentially covered state a large outer pipe diameter than the triple pipe on the outer peripheral surface of the straight tubular pipe, simple to manufacture, excellent in productivity, it can be manufactured at low cost. In addition, even if you look into the tail pipe from behind, you can see the triple pipe or the stepped part of the triple pipe or more , and it looks like it is composed of a single pipe, so the appearance is simple and the design is clean ing.
[0028]
(2) According to the second aspect of the present invention, the degree of expansion (inclination angle α: see FIG. 1B) from the end of the pipe body to the end of the outer pipe can be suppressed to a relatively gentle range of about 45 ° to 65 °. , The exhaust gas flows smoothly.
[0029]
(3) According to the invention of claim 3 , the dummy pipe is formed of a good-looking metal material, and the black tail pipe is arranged in the dummy pipe. This is ideal for placing the muffler completely exposed outside the vehicle body.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view showing an outline of an entire structure of an embodiment of a muffler of the present invention, and FIG. 1B is an enlarged view of a tail pipe portion of the muffler of FIG. 1A. FIG.
FIG. 2 is a rear perspective view showing the appearance of the entire muffler of FIG. 1 (a).
FIG. 3 is a partial sectional view showing another embodiment of the tail pipe portion of the present invention, corresponding to FIG. 1 (b).
FIG. 4 is a sectional view schematically showing a structure of a tail pipe portion of a conventional general muffler.
[Explanation of symbols]
1: Muffler 1 ': Muffler body 1A: Dummy pipe 1B: Exhaust port 1c: Front room 1d: Intermediate room 1e: Rear room 2.3: Partition wall 4: Exhaust pipe 5.6: Communication pipe 7.7': Tail Pipe 7a: Pipe body 7b: Outer pipe 7c: Discharge end 8: Rear wall 9: Bracket

Claims (3)

The tail pipe at the rear end of the muffler is placed on the outer peripheral surface of the rear part of the straight tubular pipe body, and the straight tubular outer pipe with a slightly larger diameter is stepped in a double or triple step length slightly smaller than the rear end of the pipe body. A tail pipe portion structure of a muffler, wherein the tail pipe portion is sequentially covered so as to protrude only, and an inner diameter of an end portion of the tail pipe is gradually increased. The tailpipe structure of a muffler according to claim 1, wherein the inclination angle of the enlarged diameter portion at the rear end of the tailpipe is approximately 45 to 65 ° . A large-diameter dummy pipe surrounding the periphery of the tail pipe is provided in black, and an outlet end of the tail pipe is set at a position corresponding to the dummy pipe end or at a position retracted from the dummy pipe. The tailpipe structure of the muffler described.

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