JP3062808B2 - Exhaust pipe - 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 pipe provided with a double pipe section composed of an inner pipe and an outer pipe body and connecting between an engine and a muffler.

[0002]

2. Description of the Related Art Conventionally, a structure in which a double pipe portion is provided rigidly in an exhaust pipe is known, for example, from Japanese Utility Model Laid-Open Publication No. 48-110523. A body in which at least a part of the body is formed of a bellows-shaped flexible tube is known, for example, from Japanese Utility Model Laid-Open No. 49-46113.

[0003]

In the former, the vibration generated due to the rotation and combustion of the engine is directly transmitted to the downstream exhaust system through the double pipe portion of the exhaust pipe.
There is a disadvantage that vibration noise is likely to occur in the exhaust pipe and the exhaust system on the downstream side thereof, and in the latter case, the exhaust resistance is greatly increased due to the unevenness of the inner peripheral surface of the bellows-like flexible pipe portion of the inner pipe body, and Disadvantageously, such as lowering the output of the device.

[0004] The present invention has been proposed in view of the above,
An object of the present invention is to provide an exhaust pipe capable of solving the above-mentioned conventional problems.

[0005]

According to the present invention, there is provided an exhaust pipe having a double pipe section for connecting between an engine and a muffler, wherein the double pipe section has a bellows shape. An outer pipe body having a flexible pipe portion, and an inner pipe body surrounded by the outer pipe body and having an inner diameter uniform along the length of the exhaust pipe, and an outer peripheral surface of the inner pipe body. Outside
When the outer pipe body expands and contracts,
Cylindrical shape that rubs against the outer pipe body and suppresses vibration of the outer pipe body
A vibration suppressing member is interposed, and the inner pipe body includes first and second inner pipe parts adjacent to each other along the length direction of the pipe body, and between the two inner pipe parts, Said shake
An annular discontinuous portion that is surrounded by the movement suppressing member and that allows the flexible tube portion to expand and contract is formed, and edge portions of the first and second inner tube portions that face each other across the discontinuous portion. Are characterized by having substantially the same inner diameter.

[0006] According to a feature of this, the outer pipe, in particular the deformation of the bellows-shaped flexible tube portion, vibrations transmitted from the engine to the exhaust pipe can be effectively absorbed, transmission of vibration of the downstream side to the exhaust system Since this is effectively suppressed, it is possible to effectively prevent the generation of vibration noise in the exhaust pipe and the exhaust system on the downstream side thereof. Also, most of the irregularities formed on the inner periphery of the bellows-shaped flexible tube are covered by the inner pipe body and are not exposed to the exhaust passage. The increase in resistance is minimized. Furthermore, to the inner pipe body,
Even if a discontinuous portion that allows expansion and contraction of the flexible tube portion is specially provided, first and second inner tube portions constituting the inner pipe body are opposed to each other across the discontinuous portion. Since the inner diameters are substantially the same, an increase in exhaust resistance due to the presence of the discontinuous portion can be effectively suppressed.

Further, the bellows-like flexible tube portion of the outer pipe body is extended.
The vibration suppressing member suppresses the vibration during the contraction deformation.
The bellows-like flexible tube
Effectively reduces vibration noise generated from the part due to expansion and contraction
can do. In addition, the vibration suppression member
Since the discontinuous portion of the ip body is covered, the shape of the discontinuous portion is
The increase in exhaust resistance due to the formation is suppressed as much as possible.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below based on embodiments of the present invention illustrated in the accompanying drawings.

FIG. 1 is an overall view of a first embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a main part of the first embodiment, and FIG.
FIG. 4 is an overall view of a second embodiment of the present invention, and FIG.

First, in FIGS. 1 and 2 showing the first embodiment, a muffler M is connected to an engine E mounted on a scooter V via an exhaust pipe 1 extending from the upper front surface thereof. M is supported by the engine E via elastic support means (not shown).

The exhaust pipe 1 extends from the exhaust port 6 of the engine E and is bent short downward. The exhaust pipe 1 is connected to the downstream end of the exhaust pipe 1 and is bent substantially in an L-shape to extend rearward. A long downstream exhaust pipe 1B is formed, and a front end of the muffler M is connected to a rear end of the downstream exhaust pipe 1B.

The upstream exhaust pipe 1A is formed of a double pipe section W composed of inner and outer pipe bodies Pi and Po fitted to each other, and the outer pipe body Po has a bellows shape having elasticity. A flexible tube portion 3 and a flange-shaped first portion 3a to be welded to the end portion 3a on the upstream side (that is, the engine E side) of the flexible tube portion 3
A ring portion F _1, composed of the downstream side (i.e. muffler M side) second ring portion F ₂ Metropolitan flange-like welded to the end portion 3b of the. In addition, a metal plate such as a rolled steel plate, a stainless steel plate, and an aluminum plate is selected as a constituent material of the flexible tube portion 3.

The inner pipe body Pi is formed by replacing a normal cylindrical pipe whose inner diameter is uniform along the pipe length direction with the outer pipe body Pi.
The outer pipe body Po is formed with a gap s as a discontinuous portion that allows the bellows-shaped flexible tube portion 3 to expand and contract in the longitudinal direction of the outer pipe body Po. It is provided near the downstream end of the body Po. Thus, the inner pipe body Pi
Is a relatively long first inner pipe portion 2 upstream of the gap s.
m and a relatively short second inner pipe portion 2s on the downstream side, and the upstream end portion 2ma of the first inner pipe portion 2m and the downstream end portion 2sb of the second inner pipe portion 2s (that is, the inner pipe portion 2s). Both ends of the body Pi) are the first and second ring portions F of the outer pipe body Po.
₁ and F ₂ (that is, both ends of the outer pipe body Po). In addition, the first inner pipe 2m and the second inner pipe 2s,
Edges opposed to each other across the gap s (ie, the downstream end 2mb of the first inner pipe 2m and the upstream end 2s of the second inner pipe 2s)
The inner diameter of a) is formed substantially the same. In addition, the inner pipe body Pi
As the constituent material, a metal plate such as a rolled steel plate, a stainless steel plate, and an aluminum plate is selected.

Between the inner and outer pipes Pi, Po, frictional resistance is given to the outer pipe Po (particularly, the flexible tube portion 3) during the expansion and contraction deformation in the pipe length direction to suppress vibration. As a member, a stainless steel tubular mesh body 4 is sandwiched , and this mesh body 4 covers the entire outer circumferential side of the gap s.
It surrounds over. At the time of assembling, the mesh body 4 is fitted to the inner periphery of the flexible tube portion 3 in a single state, while the first and second ring portions F ₁ and F ₂ in the single state are connected to the first and second inner tubes. The outer ends 2ma and 2sa of the portions 2m and 2s are welded, and then the inner ends of the first and second inner tube portions 2m and 2s are inserted into the flexible tube portion 3 through the openings at both ends thereof. Respectively, and thereafter, both ends 3 of the flexible tube portion 3 are inserted.
a, 3b of the first and second ring portions F _1, F ₂ and respectively welded. By doing so, it is not necessary to perform a special fixing work such as welding to the mesh body 4, and the manufacturing process can be simplified.

[0015] hitting the assembly of the upstream exhaust pipe 1A is a front end portion of the collar 5 which is integrally projected from the end face of the first ring portion F _1, which is formed in the exhaust port 6 opening of the engine E fitted via a mounting recess 6a in the seal ring 7, a stud bolt 8 planted on the engine E side, a nut 9 screwed to thereby fix the ring portion F ₁ to the engine E. The second ring portion F ₂ other is a downstream exhaust pipe 1B to abut the mounting flange portion F ₃ which is fixed to the upstream end of, between both F _2, F ₃ which, volt (not shown)
Connect with nuts.

During the operation of the engine E, high frequency vibration is generated due to the rotation and combustion of the engine E, and the vibration is transmitted to the muffler M through the exhaust pipe 1. In this case, the bellows-shaped flexible tube portion 3 of the outer pipe body Po in the upstream side exhaust pipe 1A (that is, the double tube portion W) expands and contracts and elastically deforms when the high-frequency vibration acts on the outer pipe body Po. The outer pipe body P is effectively absorbed and receives a relatively greater frictional resistance than the mesh body 4 which rubs against the flexible tube part 3 when deformed.
o The vibration of itself is suppressed, so-called so-called noise of the outer plate is avoided.
Thus, the vibration transmitted from the engine E to the upstream exhaust pipe 1A is effectively absorbed, and the vibration transmission to the exhaust system Ex (ie, the downstream exhaust pipe 1B and the muffler M) on the downstream side is effectively suppressed. Generation of vibration noise in the exhaust pipe 1A and the exhaust system Ex can be effectively prevented. In addition, most of the concave and convex portions formed on the inner periphery of the outer pipe Po due to the flexible pipe portion 3 having the bellows shape are formed in the inner pipe P.
Since the exhaust pipe is not covered with i and does not become exposed, the increase in exhaust resistance is suppressed as much as possible irrespective of the use of the bellows-like flexible tube section 3, and a decrease in engine output is avoided.

Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, a part of the upstream exhaust pipe 1A is a double pipe part W. The outer pipe body Po of the double pipe part W has a bellows-like flexible pipe part 3 having elasticity, and a short cylindrical first ring welded to the upstream end 3a of the flexible pipe part 3. and parts 10 ₁ and a short cylindrical second ring portion 10 ₂ which is welded to an end portion 3b on the downstream side.

The inner pipe body Pi is formed of a normal cylindrical straight pipe having an inner diameter uniform along the length of the pipe. The inner pipe body Pi is formed of a bellows-like flexible pipe portion 3 of the outer pipe body Po. A gap s is provided near the upstream end of the outer pipe body Po as a discontinuous portion that allows for elastic deformation in the length direction. Therefore, the inner pipe body Pi is divided into a relatively shorter first inner pipe portion 2m upstream of the gap s and a relatively longer second inner pipe portion 2s downstream of the gap s. The upstream end of the portion 2m and the downstream end of the second inner pipe portion 2s (that is, both ends of the inner pipe body Pi) are connected to the first and second ring portions 10 ₁ and 10 ₂ of the outer pipe body Po (that is, (Both ends of the pipe body Po). The first inner pipe section 2m
Is formed to have the same diameter as the pipe main body 1Aa on the upstream side of the double pipe section W of the upstream exhaust pipe 1A and is seamlessly connected to the downstream end of the main body 1Aa. Part 2s
Is seamlessly connected to the tapered upstream end of the pipe body 1Ab on the downstream side of the double pipe portion W of the exhaust pipe 1A.

A member is provided between the inner and outer pipes Pi, Po for applying frictional resistance to the outer pipe Po (particularly, the flexible tube portion 3) when the pipe is deformed in the pipe length direction to suppress vibration. , A cylindrical mesh body 4 made of stainless steel is sandwiched. In addition, between the upstream end of the upstream exhaust pipe 1A and the engine E and between the upstream exhaust pipe 1A and the downstream exhaust pipe 1B are integrally connected as in the first embodiment. .

Thus, also in this embodiment, the same operation and effect as in the above-described embodiment can be achieved by the double pipe portion W composed of the inner and outer pipes Pi and Po.

In each of the above embodiments, the double pipe portion W is provided at or near the bent portion of the exhaust pipe. However, the double pipe portion of the present invention is provided at the straight portion of the exhaust pipe. It is also possible. It is also possible to combine a large displacement flexible pipe (four-wheel type) on the downstream side of the double pipe part of the present invention. Further, each of the embodiments is an exhaust pipe for a scooter, but the present invention is also applicable to an exhaust pipe for a motorcycle, a three-wheeled vehicle, and even a four-wheeled vehicle.

[0022]

As described above, according to the present invention, the extension of the outer pipe body of the double pipe portion, particularly the bellows-like flexible pipe portion, in the exhaust pipe is performed.
The compression deformation effectively absorbs the vibration transmitted from the engine to the exhaust pipe, and effectively suppresses the transmission of vibration to the exhaust system downstream of the engine. It is effective in preventing the occurrence of. In addition, since the flexible pipe portion of the outer pipe body is formed in a bellows shape, most of the uneven portion formed on the inner circumference thereof is covered with the inner pipe body and does not become exposed in the exhaust passage. Despite the adoption of the flexible tube portion, an increase in exhaust resistance can be suppressed as much as possible, and a decrease in engine output can be prevented.

Further, a discontinuous portion is specially provided in the inner pipe body in order to allow the expansion and contraction deformation of the flexible tube portion without difficulty, and the first and second inner pipe portions constituting the inner pipe body are not provided with a discontinuous portion. Since the inner diameters of the edge portions opposed to each other across the discontinuous portion are substantially the same, an increase in exhaust resistance due to the special provision of the discontinuous portion can be effectively suppressed.

Further, the outer peripheral surface of the inner pipe and the inner
When the outer pipe body expands and contracts, the outer pipe body
Cylindrical vibration suppression part that suppresses vibration of the outer pipe body by rubbing with
Since the material is interposed, the bellows-like flexible tube of the outer pipe body is
The vibration suppressing member is configured to vibrate at the time of expansion and contraction deformation of the vibration.
Can be suppressed more effectively, thus allowing bellows
Vibration noise generated from the flexible tube due to expansion and contraction
Can be effectively reduced. Moreover, the vibration suppression member
It can cover the discontinuous part of the inner pipe body
To minimize the increase in exhaust resistance due to the formation of the discontinuous part.
Exhaust gas to flow more smoothly
it can. Also, as described above, the vibration suppression unit for the outer pipe body
Material covers the discontinuity of the inner pipe body and suppresses the increase in exhaust resistance.
Simplifies the structure as it also functions as
Can be

[Brief description of the drawings]

FIG. 1 is an overall view of a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of the first embodiment.

FIG. 3 is an overall view of a second embodiment of the present invention.

FIG. 4 is an enlarged sectional view taken in the direction of arrow 4 in FIG.

[Explanation of symbols]

 E: engine M: muffler Pi: inner pipe body Po: outer pipe body s: gap as a discontinuous portion W: double pipe section 1 ... · Exhaust pipe 2m ··· 1st internal pipe 2mb ··· Downstream end (edge) of first internal pipe 2s ··· 2nd internal pipe 2sa ··· Upstream end of second internal pipe (Edge) 3 ··· Bellows-like flexible tube

──────────────────────────────────────────────────続 き Continuing from the front page (72) Katsunori Sudo, 1-4-1 Chuo, Wako-shi, Saitama Pref. Honda Technical Research Institute Co., Ltd. (56) References Real Open 63-166614 (JP, U) Real Open Akira 57-36311 (JP, U) Japanese Utility Model Showa 57-158921 (JP, U) Japanese Utility Model Application Hei 3-61117 (JP, U) Japanese Utility Model Utility Model 4-69621 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) F01N 7/08

Claims (1)

(57) [Claims] An engine (E) having a double pipe portion (W).
In the exhaust pipe connecting between the muffler (M) and the muffler (M), the double pipe (W) includes an outer pipe (Po) having a bellows-shaped flexible pipe (3), and an outer pipe (Po) Po) and an inner pipe body (Pi) surrounded by the exhaust pipe (1) and having a uniform inner diameter along the length direction of the exhaust pipe (1), and an outer peripheral surface of the inner pipe body (Pi) and an outer pipe body (Po). )
When the outer pipe (Po) is stretched and deformed,
Rubs against the outer pipe (Po) and shakes the outer pipe (Po)
Cylindrical vibration suppression member suppressing the dynamic (4) is interposed, said pipe body (Pi), the first and second inner pipe portion adjacent to each other along the length of the pipe body (Pi) (2
m, 2s) and both inner tubes (2, 2s)
m, 2s), surrounded by the vibration suppressing member (4).
Is the flexible tube section (3) an annular discontinuity to allow expansion and contraction deformation (s) are formed, the first and second inner pipe portion (2m, 2s) of said discontinuity (s) (2mb, 2sa)
An exhaust pipe, wherein the inner diameter of the exhaust pipe is substantially the same.