JPS5813060Y2 - Heat-retaining exhaust pipe - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a heat-retaining exhaust conduit in which the front pipe connecting an exhaust manifold and a converter has a double pipe structure.

In general, the catalyst purification performance of a catalytic converter improves as the temperature increases, so in an automobile exhaust system, the exhaust pipe connecting the catalytic converter 1 and the Exis I-manifold 2 is connected internally, as shown in Figure 1. The tube 3 is covered with an outer tube 4 as a heat-retaining type exhaust conduit 5.

For example, in the heat-retaining type exhaust conduit 5 shown in FIG. 2, one end of the outer pipe 4 is welded to the inner pipe 3, and the other end is an open end 6.

The reason why the ends are open ends is that the temperature difference between the inner tube 3 and the outer tube 4 causes a difference in the amount of thermal expansion, so this open end 6 slides to absorb this difference. be.

However, at this open end 6, the sliding may cause wear of the tube and cause so-called backlash, so a spiral spring 7 as shown in FIG. 3 is fitted here to prevent the backlash. There is.

However, it is difficult and dangerous to insert the spiral spring 7 into the space 8 between the inner tube 3 and the outer tube 4, so the assembly process is difficult and costly. There is.

Further, the heat-retaining type exhaust pipe 5 also includes a type with both ends closed, as shown in FIGS. 4 and 5.

In this system, either the inner pipe 3 or the outer pipe 4 is divided into an upstream pipe 9 and a downstream pipe 10, and this side pipe 9
．． The connector portion 13 is formed by overlapping the ten mutually adjacent end portions 11j2 as illustrated in FIGS. 6a, l) and c.

However, since this connector part 13 is simply overlapped, it has the disadvantage that it is likely to rub against each other and wear due to repeated thermal expansion and contraction, and it is likely to generate abnormal noise due to vibration or the like.

Therefore, the object of the present invention is to provide a heat-retaining type exhaust pipe that eliminates the above-mentioned drawbacks, and its characteristics are that at least one of the inner pipe or the outer pipe is separated from the upstream pipe and the downstream pipe. A plurality of tongue pieces formed by making a plurality of cuts in the mutually adjacent ends of the side conduits in the axial direction are long enough to allow one conduit to slide in the axial direction with respect to the other conduit. This is because the connector part of the side conduit is formed by meshing with each other by the same amount as the connector part, so that the connector part elastically connects the side conduit. It is designed to prevent this.

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 7 is a perspective view showing an example of the heat-retaining exhaust conduit according to the present invention, with the connector portion 13 extracted.

This connector portion 13 is capable of sliding elastically and axially on mutually adjacent ends 11 and 12 when either the inner tube 3 or the outer tube 4 is composed of an upstream conduit 9 and a downstream conduit 10. It is for connecting to.

That is, in this connector part 13, a plurality of cuts are made in the mutually adjacent end portions 11 and 12 of the side conduits 9 and 10 from the axial direction to form a plurality of strip-shaped tongue pieces 14, and the tongue pieces 14 are separated by one interval. The tongues 14 are displaced inward in the radial direction by the thickness of the tongues 14, and are meshed with each other.

In particular, when making this mesh, each conduit 9, 10 thermally expands,
It is preferable that the base of the tongue of one conduit abuts the base of the tongue of the other conduit, and the connector portion 13 configured in this manner is desirably engaged for a length that does not cause distortion in the tongue or the conduit. For example, if it is provided on the inner tube 3 side, there is a risk of exhaust gas leaking from the connector portion 13, so the outer tube 4 needs to be of a type with both ends closed.

Further, when the connector portion 13 is formed on the outer tube 4 side, there is no need to worry about sealing performance, and it is sufficient to fix both ends of the outer tube 4 to the inner tube 3 by spot welding.

In particular, when the connector portion 13 is provided on the side of the outer tube 4, it is effective to provide it in the upstream region of the exhaust conduit 5 so that the amplitude when resonance occurs is small.

Next, the action will be explained.

The exhaust gas flowing down from exhaust manifold 2 is
Passes through the inner pipe 3 and is purified in the catalytic converter 1,
It flows down the muffler etc. and is discharged into the atmosphere, but this inner pipe 3
Since a space 8 is formed between the outer periphery of the catalytic converter 1 and the outer pipe 4, the exhaust gas passing through this space is kept warm and flows into the catalytic converter 1.

However, the temperature experienced by the inner tube 3 is about 500° C. while the automobile is running, and the temperature experienced by the outer tube 4 is about 250° C., so there is a large difference in thermal expansion between the two tubes.

If the connector section 13 is provided on the inner tube 3 side, both ends of the outer tube 4 will be sealed and fixed, but even if the inner tube 3 undergoes a large thermal expansion, one side of the connector section 13 will be closed. One tongue piece simply slides on the other tongue piece, and no distortion is caused to the outer tube 4.

On the other hand, if the connector section 13 is provided on the outer tube 4 side, the inner tube 3 will extend together with the outer tube 4, but in this case as well, only sliding will occur between the tongues of the connector section 13. Therefore, no distortion occurs in both the inner and outer tubes.

In particular, since the tongue piece 14 of this connector part 13 is strip-shaped and has elasticity in the radial direction, this connector part acts as a knot against vibrations transmitted from the engine or body, etc. This is to prevent vibrations from propagating to equipment installed downstream of the exhaust system, such as equipment, as much as possible.

Also, the force acting on this exhaust pipe 5 is easily 1 g.
No staining or deformation of the conduit.

In addition, since this connector part 13 is displaced inwardly or outwardly by the thickness of the tongue piece at one interval, when the side conduits 9 and 10 are engaged, the gap in this engaged part is extremely small. This means that exhaust gas leakage can be prevented as much as possible.

As is clear from the above description, according to the present invention, the exhaust pipe connecting the exhaust pipe 1 to the manifold and the converter has a double pipe structure, and of the double pipe, either the inner pipe or the outer pipe Since a connector part that can be elastically and axially displaced is provided on one side, this connector part absorbs the difference in the amount of thermal expansion between the two pipes that occurs when exhaust gas flows, and this prevents distortion from occurring in the exhaust pipe. Moreover, since this connector part has elasticity, it is possible to maintain the exhaust conduit etc. even against vibrations or external forces.

In addition, this connector part is made by making a cut in the conduit, forming a number of strip-shaped tongue pieces, and displacing them radially inward or outward by a predetermined amount so that they mesh with each other, making it easy to manufacture. Since it is extremely easy to assemble, and the number of parts is small, it has extremely excellent effects such as being advantageous in terms of cost.

[Brief explanation of the drawing]

Fig. 1 is a front view showing the entire conventional exhaust system, Fig. 2 is an enlarged sectional view of the main part of Fig. 1, Fig. 3 is an enlarged sectional view of section A in Fig. 2, and Figs. 4 and 5 are the conventional exhaust system. FIG. 6 is a cross-sectional view showing various examples of a connector section provided in a conventional exhaust conduit; FIG. 7 is a cross-sectional view showing a connector section of an exhaust conduit according to the present invention. FIG. 1...Catalytic converter, 2...Exhaust manifold, 3...Inner pipe, 4...
... Outer pipe, 5 ... Exhaust pipe, 8 ... Space, 9 ... Upstream pipe, 10 ... Downstream pipe, 11.12. ... mutually adjacent ends, 13.
...Connector part, 14...Tang piece.

Claims (1)

[Claims for Utility Model Registration] ■ In an exhaust conduit in which both ends of the outer tube are fixed to the inner tube so as to form a space for heat retention between the inner tube and the outer tube, the inner tube or At least one of the outer tubes is made up of an upstream conduit and a downstream conduit, and a plurality of strip-shaped tongue pieces formed by making a plurality of cuts in the mutually adjacent ends of the side conduit in the axial direction are attached to one side. A heat-retaining type exhaust conduit in which one of the two conduits is engaged with the other conduit by a length sufficient to allow sliding in the axial direction, thereby forming a connector portion of this side conduit. 2. The connector portion is formed by displacing a large number of strip-shaped tongues radially inward or outward at one interval by the thickness of the tongues, as set forth in claim 1. Heat-retaining exhaust pipe.