JP2007315368A - Vehicle exhaust pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve thermal insulation of a pipe while maintaining manufacturing ease with a double pipe having a flexible inner pipe. <P>SOLUTION: An air space over the whole length is formed between the outer pipe and the inner pipe which is composed of an interlocking pipe, and a supporting means is extended from a flange firmly fixed to the both ends of the outer pipe. The both ends of the air space are blocked while supporting the both ends of the inner pipe. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exhaust pipe structure of a vehicle, and more particularly to a double pipe structure excellent in heat retention of exhaust gas.

  The exhaust pipes of recent automobiles are equipped with catalytic converters, diesel particulate filters, etc. as exhaust treatment devices, and in order to operate them efficiently above a predetermined temperature, the upstream exhaust pipe has a heat retaining function. Is required. In particular, when the distance from the internal combustion engine, which is an exhaust gas generation source, to the exhaust treatment device is long, in order to prevent the temperature of the exhaust gas from decreasing, an exhaust pipe having a two-layer structure consisting of a metal outer pipe and a thin inner pipe is provided. Often used.

  In order to improve the heat retention of the exhaust pipe having a two-layer structure, an exhaust pipe having a double-pipe structure in which the inner and outer pipes are separated from each other and an air gap is provided over the entire length so that the thin inner pipe is surrounded by an air layer (hereinafter originally referred to as a double pipe). Tube). On the other hand, in the vehicle mounted state, formation of a plurality of bent portions is unavoidable because the route setting avoids other parts. For this reason, the bending process of double pipes originally requires a special process of filling and bending ice, shot grains, special cored bar, etc. in the gap and inner pipe, including the preparation and post-processing processes, and the manufacturing process. It is inevitable that equipment becomes complicated and production time and costs increase accordingly.

  Therefore, as a measure that can be dealt with by the conventional bending method without requiring the above-mentioned special process, a pseudo-dual pipe in which an uneven flexible thin-walled inner pipe is closely attached inside the outer pipe and intermittent gaps are formed by the unevenness. An exhaust pipe with a structure has been proposed. For example, in Japanese Patent Application Laid-Open No. 2001-317350, an inner tube made of a bellows tube or an interlock tube is inserted after the outer tube is bent, or an inner tube made of a bellows tube or an interlock tube is inserted into the outer tube. A double pipe that is later bent is disclosed. Japanese Patent Laid-Open No. 2003-120285 discloses that after bending the outer tube, an inner tube made of a spiral interlock tube is inserted, and a fastening flange projects into the outer tube to hold the end of the inner tube. A double tube is disclosed.

JP 2001-317350 A JP 2003-120285 A

  However, both of the double-pipe structure exhaust pipes disclosed in Patent Document 1 and Patent Document 2 provide some heat insulation by the gap formed in an intermittent ring or a spiral, but the capacity of the gap itself is essentially Compared with the double pipe, it is a little, and the heat insulating air layer is insufficient, and it is difficult to secure a desired heat insulating property. In addition, heat transfer at the line contact portion between the inner tube and the outer tube is unavoidable, and the heat retention is deteriorated by the amount of loss. Further, in the exhaust pipe having a double pipe structure disclosed in Patent Document 2, a separate inner pipe is in deep contact with the inner pipe, or a fastening flange is deeply interposed between the inner pipe and the outer pipe. In addition, since heat transfer loss increases and voids cannot be formed in this portion, there is a problem that heat retention is further deteriorated.

  In order to solve this problem, it is conceivable to arrange a flexible inner tube by securing a gap in the outer tube as in the case of the double tube, but the inner tube cannot self-hold because of its flexibility. It will be in wide contact with the outer tube and will not solve the problem. Furthermore, since the inner tube moves freely due to vibration during operation, it makes contact with the outer tube to cause abnormal noise and deformation.

  The present invention has been made in view of the above-described circumstances, and even in an exhaust pipe having a double pipe structure in which an inner pipe is flexible, the heat insulating property equivalent to that of the double pipe is inherently obtained, and thus the exhaust gas heat retaining property is obtained. The purpose is to propose an exhaust pipe.

  In order to solve the above-described problems, the present invention provides a vehicle exhaust pipe in which a flexible inner pipe is provided in an outer pipe bearing strength, and an inner pipe made of an interlock pipe is used as an outer pipe. A space is formed to be separated from the entire length, an elastic support member is disposed in the space, the outer tube and the inner tube are compressed and sandwiched, and the support means is extended from the fastening flange fixed to both ends of the outer tube. Both ends of the tube are supported and both ends of the gap are closed.

  According to a second aspect of the present invention, it is preferable that the elastic support member is a ring-shaped metal fiber complex, and a plurality of elastic support members are dispersedly arranged in the gap.

  According to a third aspect of the present invention, the elastic support member may be substantially umbrella-shaped in a cross section parallel to the central axis.

  According to the present invention, while maintaining the manufacturability of the flexible inner tube type double tube, the heat insulating property, and thus the desired exhaust gas heat retention property, can be essentially equal to the double tube.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall side view of an exhaust pipe 1 having a double-pipe structure according to the present invention. A flexible inner pipe 3 made of an interlock pipe is supported inside an outer pipe 2 that bears the overall strength of the exhaust pipe 1, and a heat insulating air layer extends between the inner pipe 3 and the outer pipe 2 over substantially the entire length. A ring-shaped void 4 is formed. Further, flanges 5 and 6 for fastening with the mating parts are externally fitted and fixed to both ends of the outer tube 2 by welding.

  In the gap 4, annular elastic support members 20 made of a metal complex (wire mesh or the like) are arranged at three locations. As shown in detail in FIG. 3, the annular elastic support member 20 having a substantially umbrella-shaped cross section that faces outward in a cross section parallel to the central axis contacts the top portion 21 with the inner surface of the outer tube 2, and the leg portions 22, 23 are arranged. In contact with the outer surface of the inner tube 3, the inner tube 3 is compressed and sandwiched between the inner surface of the outer tube 2 and the outer surface of the inner tube 3. As a result, a gap 4 having a certain thickness is secured between the inner tube 3 and the outer tube 2 to form a desired heat insulating layer.

  Since the elastic support member 20 has an umbrella-shaped cross section that is convex in the radial direction, the inner tube 3 follows the various vibrations caused by the engine and the vehicle by the deformation of the umbrella-shaped cross section in addition to the compression deformation of the complex body. Hold and damp vibrations. Therefore, the malfunction of the inner tube 3 can be prevented. Although the outer tube 2 and the top portion 21 are in line contact, there is slight heat transfer, but the number of elastic support members 20 is small (2 to 4 in a normal use state), so that the overall heat retention is hardly affected. The number of elastic support members 20 is desirably the minimum number that can support the inner tube dynamically and in a durable manner, but may be set as appropriate according to the requirements of design, manufacture, use, and the like.

  In manufacturing, when bending the outer tube 2 after inserting the inner tube 3 fitted with each elastic support member 20 into the outer tube 2, the inner tube 3 which is a flexible interlock tube is bent. In addition, the elastic support members 20 serve as spacers to secure the gap 4 between the inner tube 3 and the outer tube 2. Alternatively, even when the inner tube 3 in which each elastic support member 20 is externally fitted is inserted into the outer tube 2 that has been previously bent, the inner tube 3 follows the bent shape of the outer tube 2 and each The elastic support member 20 serves as a spacer, and the desired gap 4 can be secured between the inner tube 3 and the outer tube 2.

  In any step, when inserting the inner tube 3 fitted with each elastic support member 20 into the outer tube 2, as shown in FIG. It is preferable that the diameter is reduced by a plurality of turns of the combustible adhesive tape 50 or the like and temporarily fixed to the inner tube 3. Accordingly, each elastic support member 20 is fixed at a predetermined position and the outer diameter D is kept smaller than the inner diameter of the outer tube 2, so that it is possible to prevent an obstacle at the time of insertion. After insertion into the outer tube 2, the combustible adhesive tape is thermally decomposed or burned down by the high-temperature exhaust gas during the first operation, and each elastic support member 20 is restored to its original diameter to create the gap 4 and the inner tube 3. Delivers an elastic holding function. In addition, the winding method of the combustible adhesive tape 50 is arbitrary. Further, the outer diameter D may be set as appropriate in consideration of the clearance with the outer tube 2 necessary for facilitating insertion work. As the combustible adhesive tape 50, for example, a commercially available cellophane adhesive tape, a masking tape, or the like is suitable.

  The inner tube 3 supporting method at both ends will be described in detail with reference to FIG. Inside the annular seating surface 13 which is a recess formed in the fastening flange 5, the flange portion 11 of the outer holder 7 and the flange portion 12 of the inner holder 8 are fixed in a laminated state by spot welding or the like. Then, the straight pipe portion 9 continues to the flange portion 11, and the straight pipe portion 10 extends to the outer tube 2 continuously to the flange portion 12, and the straight pipe portions 9 and 10 connect the end portion of the inner tube 3. The lap portion 14 is fixed by spot welding or the like in the sandwiched state. As a result, the inner tube 3 is securely supported by the fastening flange 5 via the outer holder 7 and the inner holder 8, and the gap 4 is also separated. The same applies to the other end. The outer holder 7 and the inner holder 8 serving as support means are preferably made of a thin plate (for example, t1.0) with a limit to ensure the support strength from the viewpoint of heat mass reduction, and the collar portion and the straight pipe portion are formed into an integral hat shape. What is necessary is just to form by press work. Further, the outer tube 2 may not be integrated but may be cut as appropriate, or may have a non-circular cross section or a shape in which the cross section gradually changes. Further, in the wrap portion 14, the end portion of the inner tube 3 may be slid without being fixed.

  Since the exhaust pipe 1 has such a configuration, the heat insulation and heat retention can be made equal to or higher than that of the double pipe while maintaining the merit of the flexible inner pipe type double pipe that is easy to manufacture. . In particular, since the gap 4 is reliably separated by the holder at both ends of the inner tube 3 and the both ends of the gap 4 are blocked by the flanges, the blocked heat insulating air layer extends over the substantially entire length of the outer tube 2. It can be secured to the maximum.

  In addition, in the case of a double pipe, the limit of thinning the inner pipe (single pipe) is about t0.8 due to problems of wrinkles and cracks during bending, but according to the present invention, the flexible inner The tube 3 can be further thinned (for example, t0.3 to 0.5). Therefore, since the heat mass of the inner pipe 3 can be reduced compared to the double pipe, and the exhaust gas temperature drop at the beginning of every operation (during cold operation) can be minimized, the operation of the exhaust treatment device can be accelerated to purify the exhaust gas. Contribute further.

  FIG. 4 shows a second embodiment of holding the inner tube 3 by an elastic support member. An annular elastic support member 30 made of a metal complex (wire mesh or the like) disposed in the gap 4 has a substantially rectangular cross section. Since the support load can be set larger than that of the umbrella-shaped cross section of the first embodiment, it is suitable when the inner tube 3 is heavy or when the vibration is large. As in the first embodiment, the elastic support member 30 may be temporarily fixed to the inner tube 3 at the time of manufacture.

  FIG. 5 shows a third embodiment of holding the inner tube 3 by an elastic support member. An annular elastic support member 40 made of a metal complex (wire mesh or the like) disposed in the gap 4 has a substantially Ω-shaped cross section. The same support effect as that of the umbrella-shaped cross section of the first embodiment is achieved, and the leg portions 41 and 42 are fixed to the inner tube 3 by spot welding, TIG welding, or the like, so that temporary fixing for positioning is unnecessary. . In addition, axial movement (displacement) can be prevented especially when vibration is severe.

    As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, Even if there is a change of the range which does not deviate from the meaning of this invention, it is included by this invention. The applied vehicle type and the internal combustion engine are not particularly limited, but are particularly suitable for exhaust pipes for large diesel vehicles having a large diameter, a large size, and difficult to bend specially.

It is a side view of the exhaust pipe which concerns on 1st Embodiment. It is an edge part detailed sectional view concerning a 1st embodiment. It is a detailed sectional view of the inner pipe support part concerning a 1st embodiment. It is a detailed sectional view of an inner pipe support part concerning a 2nd embodiment. It is a detailed sectional view of an inner pipe support part concerning a 3rd embodiment. It is a figure which shows the temporary fix | stop state of the elastic support member 20. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust pipe 2 Outer pipe 3 Inner pipe 4 Space | gap 5,6 Fastening flange 7,8 Holder 9,10 Straight pipe part 11,12 collar part 13 Annular seating surface 14 Lap part 20,30,40 Elastic support member 21 Top part 22 , 23,41,42 Leg 50 Flammable adhesive tape D Outer diameter

Claims (3)

In an exhaust pipe of a vehicle in which a flexible inner pipe is installed in an outer pipe that bears strength,
A space is formed by separating the inner pipe made of the interlock pipe from the outer pipe,
An elastic support member is sandwiched between the outer tube and the inner tube in the gap,
A fastening flange is fixed to both ends of the outer tube and a supporting means is extended from the fastening flange to the inside of the outer tube,
The support means supports both ends of the inner tube and closes both ends of the gap.
An exhaust pipe for a vehicle. The elastic support member is a ring-shaped metal fiber complex,
A plurality are dispersedly arranged in the gap.
The exhaust pipe of a vehicle according to claim 1. The elastic support member is substantially umbrella-shaped in a cross section parallel to the central axis.
The exhaust pipe for a vehicle according to claim 2.

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