JP3495487B2 - Vehicle exhaust system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system used in a vehicle such as a motorcycle.

[0002]

2. Description of the Related Art It is known that a perforated tapered tube is provided near the exhaust inlet inside a muffler to obtain a sound deadening effect.

It is also known to insert the rear end of the exhaust pipe into the muffler to form a double pipe structure in the vicinity of the exhaust inlet of the muffler, as shown in Japanese Patent Laid-Open No. 56-23513.

[0004]

Even in the case where the perforated tapered tube is used, it is necessary to make the perforated tapered tube relatively long in order to obtain a predetermined muffling effect, and as a result, the muffler. The whole tends to be long.

On the other hand, in terms of vehicle body design, it is desired that the muffler be as short and compact as possible.

Further, when the rear end of the exhaust pipe is inserted into the muffler, a support member for supporting the exhaust pipe is required inside the muffler, and a reinforcing plate is required because the perforated portion is relatively long. Become.

In addition, it is difficult to machine the rear end of the exhaust pipe into a perforated taper portion, and even if the perforated taper portion could be formed integrally, the shape would be limited.

[0008]

The invention according to claim 1 is
An exhaust pipe extending from the engine and a muffler connected to the rear end of the exhaust pipe are provided, and a plurality of perforated tapered pipes that are narrowed in the exhaust gas advancing direction are provided near the exhaust inlet of the muffler.
At least one of the exhaust systems for vehicles installed on the steps
Arrange a perforated tapered pipe inside the rear end of the exhaust pipe connection
At the same time, connect the rear end of this exhaust pipe connecting part to the muffler.
By continuing, the perforated tapered pipes near the exhaust inlet are provided in a plurality of stages.

According to a second aspect of the present invention, in the first aspect of the invention, the perforated tapered pipe is attached by spot welding.
Characterized in that it is.

According to a third aspect of the present invention, in the first aspect of the invention, the rear end portion of the exhaust pipe connecting portion is a rear end portion of the exhaust pipe.
It is equipped with an intermediate cylinder that fits into this
Accommodates a perforated tapered tube and has a mounting flange around it
Is provided, and with this mounting flange sandwiched, the front
Exhaust pipe and intermediate tube, and intermediate tube and the tapered taper tube with holes
Each is characterized by being welded .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an exhaust system configured for a motorcycle will be described with reference to the drawings. 1 is an enlarged cross-sectional view of a main part, FIG. 2 is an assembled state, FIG. 3 is an external view of a state in which an exhaust pipe and a muffler are connected, FIG. 4 is a longitudinal cross-sectional view thereof, and FIG. 5 is an exhaust pipe rear end. The external shape of each part is shown.

In FIGS. 3 and 4, the rear end of the exhaust pipe 1 extending rearward from an exhaust port of an engine (not shown) forms a rear end portion 2 and is located at a position lower than the front end by the size of the fitting portion. A mounting flange 3 is provided.

The rear end 2 has an exhaust inlet 5 (see FIG. 2) of the muffler 4.
(Refer to FIG. 3), and the flange 3 and the end surface of the muffler 4 are overlapped with each other and fastened by bolts 6 to be integrated.

The muffler 4 has an inner and outer double cylinder structure of an inner cylinder 7 and an outer cylinder 8, and a sound deadening material such as glass wool is interposed between the inner cylinder 7 and the outer cylinder 8.

Partition members 10, 11, 1 are provided inside the inner cylinder 7.
It is divided into first chamber 13 to fourth chamber 16 by 2.

A first taper pipe 20 is provided near the exhaust inlet 5.
Is supported by the support member 17 on the axial center portion, one end of which extends in the vicinity of the exhaust inlet 5 and the other end of which extends through the partition member 10
It communicates with the inside of the chamber 14.

The first taper pipe 20 is gradually narrowed to a tapered shape in the exhaust gas outflow direction (G in the drawing).
In addition, a large number of small holes 21 communicating with the first chamber 13 are formed in the periphery. The small holes 21 have different hole diameters depending on the formation location, and the small holes 21a on the downstream side in the outflow direction are formed to have a smaller diameter than the small holes 21b on the upstream side.

The support member 17 has a tubular portion 18 protruding toward the exhaust inlet 5, and the rear end portion 2 inserted from the exhaust inlet 5 is fitted into the tubular portion 18 to be connected to the first tapered pipe 20.

The second chamber 14 and the fourth chamber 16 have an intermediate pipe 22.
The fourth chamber 16 and the third chamber 15 communicate with each other through the intermediate pipe 23, and the exhaust inlet 5 communicates with the outside air through the tail pipe 24.

As is apparent from FIGS. 1, 2 and 5, a second taper pipe 30 is attached inside the rear end portion 2 of the exhaust pipe 1.

The second taper pipe 30 is also narrowed in the exhaust gas flow-out direction G, and a large number of small holes 31 are formed around it. The hole diameter of the small hole 31 is formed to be substantially the same as the hole diameter of the small hole 21b.

Therefore, when the rear end portion 2 is inserted into the exhaust gas inlet 5, another step is provided in front of the first taper pipe 20, a total of 2 stages.
A tapered portion of the step is formed.

To make this second taper tube 30, first, a plate-like member is punched into a large number of small holes 31 at the same time by press-cutting into a substantially fan shape.

When this is rolled up and inserted into the inside of the rear end portion 2 and the hand is released, it is positioned on the inner circumference of the rear end portion 2 by its repulsive elasticity.

In this state, the outer peripheral portion of the rear end portion 2 can be easily formed by spot welding about 3 points.

Therefore, the workability is improved and the degree of freedom in the shape of the second tapered tube 30 is increased.

Next, the operation will be described. As shown in FIG. 2, the rear end 2 of the exhaust pipe 1 is fitted into the exhaust inlet 5 of the muffler 4, the tip of the rear end 2 is fitted into the tubular portion 18 of the support member 17, and the flange 3 is fitted into the muffler. Attach to base 4a of 4 with bolt 6.

As a result, the rear end portion 2 of the exhaust pipe 1 is connected to the tapered pipe 20, and as shown in FIG. 1, a two-stage perforated tapered pipe structure is formed near the exhaust inlet 5 of the muffler 4. .

Therefore, when the exhaust gas flows through the exhaust device, the exhaust gas reaching the rear end portion 2 from the exhaust pipe 1 is throttled by the second taper pipe 30 and the exhaust noise is absorbed by the many small holes 31. While proceeding, the inside of the first taper pipe 20 is advanced.

In the first taper pipe 20, exhaust noise is further absorbed by diffusing into the first chamber 13 through its own narrowed shape and a large number of small holes 21. Further, since the hole diameter of the small hole 21a on the downstream side is formed smaller than the hole diameter of the small hole 21b on the upstream side, the exhaust noise is more effectively silenced.

First taper pipe 20 and second taper pipe 3
After the taper portion by 0, a predetermined silencing effect is obtained by the same structure as the conventional one.

As described above, when the two-stage perforated tapered pipe is provided on the exhaust inlet 5 side of the muffler 4, the first tapered pipe 2
Since a sufficient muffling effect can be obtained without increasing 0, the overall length of the muffler 4 can be shortened to achieve compactness.

Moreover, since it is not necessary to lengthen the rear end portion 2 inserted into the exhaust gas inlet 5, a dedicated supporting member is not required, and the supporting member 17 can be shared with the first tapered pipe 20.

Moreover, by providing the second taper pipe 30 on the rear end portion 2 side, the second taper pipe 30 is inserted into the rear end portion 2.
Can be easily formed, and since such a two-stage perforated tapered pipe structure can be obtained only by fitting the rear end portion 2 into the exhaust inlet 5 of the muffler 4, manufacturing is facilitated.

The invention of the present application is not limited to the above-mentioned examples, but can be variously modified, and the perforated tapered tube may have a multiplicity of stages of three or more. Furthermore, it can be applied to various vehicles other than motorcycles.

Further, the rear end portion of the second taper pipe 30 is set to the first end.
The first taper tube 20 and the second taper tube 30 may be at least partially overlapped with the inside and the outside by being inserted into the taper tube 20. Further, at this time, the tip end side of the first taper pipe 20 may be welded and integrated around the second taper pipe 30.

Next, an exhaust system according to another embodiment will be described with reference to FIG. FIG. 6 is an enlarged cross-sectional view of the vicinity of the rear end portion 2 of the exhaust pipe 1, and shows the second tapered pipe 30 of the previous embodiment.
The second taper pipe 130 configured in the same manner as the above is provided with the rear end portion 2 of the exhaust pipe 1 via the intermediate cylinder 150 which is a separate cylindrical member.
Connected to.

The configuration shown in this drawing is only the rear end portion 2 of the exhaust pipe 1 and the second taper pipe 130 side.
The muffler 4 side is similar to that of the previous embodiment.

As is clear from this figure, the intermediate cylinder 15
0 is substantially the same diameter as the rear end portion 2 of the exhaust pipe 1, and the muffler 4
The large-diameter portion 152 is inserted into the inside, and the small-diameter portion 154 is fitted in the rear-end portion 2 and has a diameter smaller than that of the large-diameter portion 152 by the thickness of the rear-end portion 2 of the exhaust pipe 1. A step portion 156 is formed between the small diameter portion 154 and the small diameter portion 154.

A mounting flange 103 is provided on the outer periphery of the large diameter portion 152 near the step 156. The mounting flange 103 is similar to the mounting flange 3 of the previous embodiment.

A large number of small holes 131 are formed in the taper portion of the second taper pipe 130, which is inserted into the large diameter portion 152 and positioned by the step portion 156.
The intermediate cylinder 150 and the four places are fixed by spot welding. In the figure, 160 indicates a spot weld.

The small-diameter portion 154 is fitted into the step portion 156 until the open end of the rear end portion 2 of the exhaust pipe 1 is locked, and the plug holes 162 are provided at four positions in the rear end portion 2 in the circumferential direction. It is plug-welded with the exhaust pipe 1. In the figure, reference numeral 164 indicates a plug welded portion.

The step portion 156, the flange 103, and the open end of the rear end portion 2 are welded all around the entire three members.
Reference numeral 6 denotes an entire circumference welded portion, and this entire circumference welded portion 166 is formed on the opposite side of the welded portion 160 with the mounting flange 103 interposed therebetween.

Next, the operation of this embodiment will be described. Second
The taper tube 130 is inserted into and fixed to the intermediate tube 150 having a relatively short tube length. Therefore, the insertion work becomes easier than the case of directly inserting the exhaust pipe 1 having a long pipe length. Further, since the step portion 156 is provided, the positioning of the second tapered tube 130 is easy and reliable.

Further, the intermediate cylinder 150 is connected to the rear end portion 2 of the exhaust pipe 1.
Even when assembled by fitting and welding, the welded portion 160 and the entire circumference welded portion 166 are formed so as to sandwich the flange 103, so that stress concentration on these welded portions can be relieved.

In addition, the mounting flange 103 is the exhaust pipe 1
Since the rear end 2, the intermediate cylinder 150, and the second tapered pipe 130 are fixed at the portions where the three members are joined together, the attachment of the attachment flange 103 to the exhaust pipe 1 side becomes firm. Therefore, with these structures, the connecting portion between the exhaust pipe 1 and the muffler 4 is strengthened, and the durability of the exhaust device as a whole is improved.

[0047]

According to the exhaust system of the present invention, a sufficient muffling effect can be obtained by providing a plurality of perforated tapered pipes in the vicinity of the exhaust inlet, so that the overall length of the muffler can be shortened to be compact. You can

[0048] Also, since the forming at least one perforated tapered tube inside the exhaust pipe connecting rear end portion, the muffler of the exhaust inlet by connecting the rear end portion of the exhaust pipe to the muffler
It is possible to easily provide a tapered pipe structure having a plurality of holes in the vicinity of the mouth . Furthermore, if the perforated tapered tube is attached by spot welding, the manufacturing can be made easier. Also, make sure that the rear end of the exhaust
It is equipped with an intermediate tube that fits in it, and the hole is
It accommodates an open taper pipe and has a mounting flange around it.
It is provided and sandwiches this mounting flange,
Install the exhaust pipe and the intermediate pipe, and the intermediate pipe and the tapered pipe with holes.
Welding each reduces the stress concentration on these welds.
Can be harmonized. Moreover, the exhaust pipe side of the mounting flange
Since the mounting against the
The connecting part is strengthened and the durability of the exhaust system as a whole is improved.
To do.

[Brief description of drawings]

[FIG. 1] Enlarged sectional view of main parts

FIG. 2 is an enlarged sectional view of an essential part for explaining an assembled state.

[Figure 3] Overall appearance

FIG. 4 is a longitudinal sectional view of a muffler having an exhaust pipe connected thereto.

FIG. 5 is a perspective view of a main part

FIG. 6 is an enlarged sectional view of an essential part of an exhaust pipe according to another embodiment.

[Explanation of symbols]

1: Exhaust pipe, 2: Rear end part, 4: Muffler, 5: Exhaust inlet, 20: First taper pipe, 30: Second taper pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-173633 (JP, A) JP-A-61-275519 (JP, A) Practical development Sho-61-187909 (JP, U) (58) Investigation Field (Int.Cl. ⁷ , DB name) F01N 1/08

Claims (3)

(57) [Claims] 1. An exhaust pipe extending from an engine and a muffler connected to a rear end portion of the muffler, wherein a plurality of tapered tapered pipes are provided near an exhaust inlet of the muffler, the perforated tapered pipe being narrowed in a traveling direction of exhaust gas. in the exhaust system of the vehicle it was, small
At least one perforated tapered pipe in the rear end of the exhaust pipe connection
And the rear end of this exhaust pipe connecting part
An exhaust system for a vehicle , wherein the perforated tapered pipe near the exhaust inlet is provided in a plurality of stages by connecting to a muffler . 2. A tapered pipe having a hole is attached by spot welding.
Exhaust device for a vehicle according to claim 1, characterized in that eclipsed. 3. A rear end of the exhaust pipe connecting portion is a rear end of the exhaust pipe.
It is equipped with a part and an intermediate tube that fits in this
The perforated taper pipe is housed and the surrounding mounting bracket
And the mounting flange is sandwiched.
, The exhaust pipe and the intermediate cylinder, and the intermediate cylinder and the perforated taper
Exhaust device for a vehicle according to claim 1, characterized in that the over tube was welded.