JP2002317630A - Inner-outer double-tube type exhaust pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a chattering sound in an exhaust pipe of inner-outer double-tube type exhaust pipe caused by wear generated between a separate protrusion and its contact part due to long-time use. SOLUTION: An inner-outer double-tube type structure is provided by constituting an exhaust pipe 1 of an outer pipe 10 and an inner pipe 11 coaxially arranged inside it, and at its rear end, a separate protrusion 15 is protruded inward from the outer pipe 10 and brought into contact with the inner pipe 11, and the inner pipe 11 is made capable of sliding. The separate protrusion 15 is provided in plural in the circumferential direction, and a suppressing member 18 is slightly pressed into a clearance 17 of an outward projection 16 formed between the adjacent separate protrusions 15 and plug welded to the outer pipe 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal / external double pipe type exhaust pipe used for motorcycles and the like, and more particularly to an exhaust pipe which does not generate chattering noise even when used for a long time.

[0002]

2. Description of the Related Art An exhaust pipe connecting between an engine and a muffler has an inner / outer double pipe structure, and a separate projection is formed on an outer pipe at a rear end thereof so as to protrude radially inward.
The separate projection is brought into contact with the inner tube to support the inner tube so as to keep a predetermined distance from the outer tube, and to extend the inner tube relative to the outer tube by elongation due to thermal expansion (hereinafter referred to as thermal elongation). A structure in which an inner pipe is slidably supported in order to allow it is known (JP-A-11-303632).
No.).

[0003]

However, even in the above-mentioned structure, a minute wear gap due to abrasion occurs between the separate projection and the inner pipe due to long-term use, and the inner pipe self-oscillates due to the abrasion gap. Chattering noise may be generated. Therefore, an object of the present invention is to effectively prevent the generation of such chattering sound.

[0004]

In order to solve the above-mentioned problems, an inner / outer double pipe type exhaust pipe according to the present invention has a separate projection which projects from one side of an outer pipe or an inner pipe to the other side and abuts thereon. A plurality of inner and outer duplex members are provided at predetermined intervals in the direction, and the inner protrusion is held at a predetermined interval inside the outer tube by the separate protrusions, and the contact partner is slidably supported at the contact portion of the separate protrusions. In a tubular exhaust pipe, a suppressing member for press-fitting the inner pipe to the separate projection is press-fitted into a gap formed in the inner and outer pipes.

At this time, the separate protrusion may be formed from the outer tube toward the inner tube, and the holding member may be fixed to the outer tube by welding.

[0006]

When the holding member is press-fitted into the gap between the outer tube and the inner tube, the inner tube is strongly pressed against the separate projection by the holding member. When used in this state for a long period of time, even if wear occurs between the separate protrusion and the contact partner, the inner tube and the separate protrusion are kept in close contact by pressing the suppressing member, so that the inner tube does not generate self-excited vibration, As a result, generation of chattering sound can be prevented.

At this time, if the holding member is welded to the outer tube, the holding member can be reliably positioned, and press-fitting of the holding member can be simplified. In addition, since no welding marks remain on the sliding surface, it is not necessary to perform a special finishing process on the sliding surface of the holding member to secure the sliding of the inner tube.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment will be described with reference to the drawings. FIG. 1 is a side view of a motorcycle to which the inner / outer double pipe type exhaust pipe of this embodiment is applied, FIG. 2 is a side view of an exhaust system including the inner / outer double pipe exhaust pipe of this embodiment, FIG. Is 3 in FIG.
3 is a sectional view taken along line 3-4, FIG. 4 is a sectional view taken along line 4-4 in FIG. 3, FIG. 5 is a view showing a welded portion of the holding member, and FIG. 6 is an enlarged sectional view showing the welded structure.

As shown in FIG. 1, an exhaust pipe 1 has an exhaust upstream end (hereinafter referred to as a front end) connected to an exhaust port of an engine 2, and a portion extending therefrom extends downward from the front of the engine 2. It extends around the rear of the vehicle body, connects the downstream end of the exhaust (hereinafter, referred to as the rear end) to the muffler 3, and connects the engine 2
The exhaust gas is guided to the muffler 3 and further discharged from the exhaust gas into the rear space of the vehicle body.

In the drawing, reference numeral 4 denotes a head pipe, 5 denotes a body frame, 6 denotes a pivot shaft, and 7 denotes a front end portion which is swingably supported by the vehicle body by a pivot shaft 6 and a rear wheel (not shown) is provided at a rear end portion. The supporting rear swing arm 8 is a rear cushion unit provided between the vehicle body frame and the rear swing arm.

In FIG. 2, the exhaust pipe 1 has an inner / outer double pipe structure of an outer pipe 10 and an inner pipe 11. A flange 12 is provided at the front end of the exhaust pipe 1, and is attached to an exhaust port of the engine 2 here. The rear end of the exhaust pipe 1 is fitted and connected to the joint pipe 13.

The joint pipe 13 extends inside the muffler 3 to the exhaust downstream side, and guides the exhaust gas into the main body of the muffler 3. The small diameter portion 14 formed on the front end side of the muffler 3 covers the connection between the exhaust pipe 1 and the joint pipe 13, and is welded to the outer surface of the outer pipe 10 together with the joint pipe 13.

As shown in FIGS. 3 and 4, each of the outer pipe 10 and the inner pipe 11 is a round pipe made of an appropriate metal such as iron, and the inner pipe 11 is spaced from the outer pipe 10 by a predetermined gap. D is maintained substantially concentrically, and a separate projection 15 for maintaining the concentricity is formed at the rear end of the exhaust pipe 1 so as to project from the outer pipe 10 toward the inner pipe 11.

The separate projection 15 is formed by integrally projecting the rear end of the outer tube 10 inward in the radial direction by press molding and supporting the outer tube 10 in contact with the outer periphery of the inner tube 11. Four pipes 10 are formed at equal intervals in the circumferential direction, and the protrusion height thereof is substantially the same as the gap D between the outer pipe 10 and the inner pipe 11. The contact portion of the separate projection 15 with the inner tube 11 is slidable to enable expansion and contraction due to thermal expansion of the inner tube 11.

As apparent from FIG. 4, the outer tube 10 and the inner tube 1
1 is integrated at the rear end portion at the separate projection 15 portion, but at the front thereof, the inner tube 11 is concentrically arranged inside the outer tube 10 to maintain a predetermined interval D.

As shown in FIG. 3, an outer projection 16 projects radially outward from the inner tube 11 between the adjacent separate projections 15, and a gap 17 is formed inside the outer projection. . The outer projection 16 is a representation when the outer tube 10 is viewed from the inner tube 11 side, and is a portion of the rear end of the outer tube 10 that remains as a non-molded portion when the separate projection 15 is formed. Therefore, the outer peripheral portion of the outer projection 16 is the original outer diameter portion of the outer tube 10, and the width of the gap 17 in the radial direction is a predetermined interval D.

The holding member 18 is inserted into one of the gaps 17.
Is press-fitted and plug-welded to the outer projection 16 by a plug 19. The holding member 18 is made of an appropriate metal material such as iron, and the thickness T is set so as to be slightly larger than the radial width of the gap 17, that is, a predetermined distance D between the outer tube 10 and the inner tube 11. Pressed in by light press-in to the extent that it is pushed.

As is apparent from FIGS. 4 and 6, the end of the pressing member 18 which is press-fitted is formed into a thin shape such as a round shape or a tapered shape to facilitate press-fitting, and FIG.
As shown in FIG. 3, the length is slightly shorter than the length of the separate protrusion 15, and as shown in FIG. 3, it is bent in an arc shape so as to slide on the outer periphery of the inner tube 11.

FIG. 5 is a view showing the separate projection 15 and the holding member 18 of the outer tube 10 from the direction indicated by the arrow Y in FIG. 4, and the holding member 18 is attached to the outer projection 16 which is the rear end of the outer tube 10. The outer tube 10 is plug-welded via the plug 19 inserted into the formed through hole 20. FIG. 6A is a cross-sectional view taken along the line 6-6 in FIG. 5 schematically showing the welding structure.

The fixing of the holding member 18 is not limited to plug welding, and other appropriate welding methods can be used. In FIG. 6B, fillet welding is performed between the end faces of the holding member 18 and the outer tube 10.
Even in this case, there is no problem as long as the weld bead does not reach the inner pipe 11, and the sliding of the holding member 18 and the inner pipe 11 is enabled.

Next, the operation of this embodiment will be described. As shown in FIG. 3, by pressing the holding member 18 into the gap 17, the inner pipe 11 is pressed against the separate projection 15 on the opposite side with some elastic deformation. In this state, when the inner tube 11 is relatively elongated with respect to the outer tube 10 due to thermal expansion, the inner tube 11 slides on the separate protrusion 15 and the pressing member 18 and contracts when cooled, and slides again.

Therefore, if the inner tube 11 is used for a long period of time, the contact portion between the separate projection 15 and the holding member 18 of the inner tube 11 will be worn. The inner tube 11 is pressed against the separate protrusion 15 by the pressing suppressing member 18 to maintain the contact. For this reason, since there is no abrasion gap between the inner tube 11 and the separate protrusion 15 and self-excited vibration of the inner tube 11 is not generated, it is possible to prevent chattering noise that may be caused by long-term use.

Further, by forming the separate projection 15 integrally with the outer tube 10, the separate projection 15 can be easily formed. Further, chattering noise can be prevented with a simple structure in which only one pressing member 18 is pressed into the gap 17 generated by the formation of the separate projection 15.

In addition, since the holding member 18 is fixed to the outer tube 10 by plug welding, the holding member 18 needs to be lightly press-fitted, and the assembling work becomes easy. In addition, the holding member 18 can be reliably positioned by plug welding to the outer pipe 10 side, and the outer pipe 10 can be fitted inside the joint pipe 13 without special post-processing, and can be connected to the inner pipe 11. No welding marks remain on the sliding surface of the holding member 18, so that it is not necessary to perform a special finishing process on the sliding surface of the holding member 18 to secure the sliding of the inner tube 11.

FIG. 7 is a view showing the same parts as in FIG. 3 according to the second embodiment. In this example, three separate projections 15 are formed at equal intervals in the circumferential direction, and as a result, the restraining member 18 is press-fitted into one of the three gaps 17. The structure and fixing structure of the holding member 18 are the same as those in the previous embodiment (illustration of the welded portion is omitted). Note that common parts with the previous embodiment use common codes. The same applies to the following embodiments.

FIG. 8 relates to a third embodiment, in which the outer tube 10 and the inner tube 11 are the same as in the first embodiment (FIG. 3). , 18
Is press-fitted. By doing so, the inner tube 11 can be pressed more strongly against the separate protrusions 15 located on the opposite side of the holding members 18 with the center thereof interposed therebetween.

FIG. 9 shows a fourth embodiment. In this embodiment, two separate projections 15 are formed at 180 ° intervals at opposing positions across the center of the outer tube 10. However, the separate protrusion 15 is curved so as to protrude inward in the radial direction and protrudes inward from the inner diameter R11 of the inner tube 11, and the corresponding portion of the inner tube 11 also moves inward from the inner diameter R11. The separate protrusion 15 and the curved portion 21 are in close contact with each other.

The outer projection 16 and the gap 17 are arranged opposite to each other at a position different from the separate projection 15 by 90 ° at 180 ° intervals, and the pressing members 18, 18 are pressed into the respective gaps 17, 17. I have. R10 is the outer diameter of the outer tube 10, and the inner tube 11 is arranged concentrically inside the outer tube 10 at a predetermined interval except for the rear end portion where the separate protrusion 15 is formed, as in the previous examples.

By doing so, the close contact between the outer tube 10 and the inner tube 11 can be improved in the separate projection 15 and the curved portion 21, and even when used for a long time, the holding members 18, 18 which are arranged to face each other can provide Since the separate projections 15 and 15 and the curved portions 21 and 21 that are opposed to each other are kept in close contact with each other, chattering noise can be prevented as in the previous embodiments.

The present invention is not limited to the above embodiment, and various modifications and applications can be made within the same principle. For example, the application of the exhaust pipe is not limited to motorcycles,
Applicable to cars and other engines. Holding member 18
The number of used is not limited as long as it is 1 or more, and can be press-fitted into all or a part of the gap 17 as shown in each of the above embodiments. The material is not limited to metal, and any material having a certain degree of hardness, durability and heat resistance can be used.
The degree of press-fitting includes various types, such as direct press-in by hand or light press-fitting with a hand tool such as a hammer to press-fitting with a large pressure by a power unit. Further, the holding member 1
8 may be fixed to the inner pipe 11, and the fixing method is not limited to welding.

The formation of the separate projections 15 depends on the outer tube 1.
It is not limited to the 0 side, and may be provided on the inner tube 11 side. Further, the separate protrusion 15 may be formed separately from the outer tube 10 and the inner tube 11. In this case, it is preferable to fix the separate projection to either the outer tube 10 or the inner tube 11.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle to which a double-pipe exhaust pipe according to the present invention is applied.

FIG. 2 is a side view of an internal / external double pipe exhaust pipe.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 in FIG. 3;

FIG. 5 is a view showing a welded portion of a holding member.

FIG. 6 is an enlarged sectional view showing the welding structure.

FIG. 7 is a diagram according to a second embodiment.

FIG. 8 is a diagram related to a third embodiment.

FIG. 9 is a diagram related to a fourth embodiment.

[Explanation of symbols]

1: exhaust pipe, 2: engine, 3: muffler, 10: outer pipe, 11: inner pipe 15: separate projection, 16: outer projection, 17: gap, 18: holding member

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Naofumi Kurako 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3G004 AA02 BA02 DA14 DA21 GA06 3H111 AA01 BA01 CA14 CA16 CC17 DA10 DA13 DB11 DB20 EA09

Claims (2)

[Claims] An inner / outer double tube structure is provided, and a plurality of separate protrusions are provided at predetermined intervals in a circumferential direction so as to protrude from one side of the outer tube and the inner tube to the other side and abut on the inner tube. In the inner / outer double pipe type exhaust pipe, which is held at a predetermined interval inside the outer pipe and slidably supports a contacting partner side at a contact portion of the separate projection, a gap formed in the inner / outer pipe is provided. An inner / outer double-pipe exhaust pipe, wherein a pressing member for press-fitting the inner pipe to the separate projection is press-fitted. 2. The inner / outer double tube type according to claim 1, wherein the separate projection is formed from the outer tube toward the inner tube, and the holding member is fixed to the outer tube by welding. Exhaust pipe.