JP3370981B2 - 2-pass double 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 suitable for being connected between an exhaust manifold of a multi-cylinder engine and a catalytic converter, and having an exhaust passage for preventing exhaust interference between cylinders. An exhaust pipe that uses a so-called θ pipe that is divided into two passages with a partition plate, and that has a double pipe to prevent the temperature of the exhaust from dropping to the catalytic converter and to prevent heat damage. Regarding

[0002]

2. Description of the Related Art It is conventionally known to use a two-passage dual exhaust pipe in order to prevent exhaust interference and heat radiation in the exhaust pipe (for example, Japanese Patent Laid-Open No. 9-192727). An exhaust pipe of this kind is indicated by the symbol E in FIG. 8 and is connected to the flange f2 of the exhaust manifold M. The exhaust pipe E has an inner pipe a and an outer pipe b welded to a flange f1, and a diametrical partition plate c is provided inside the inner pipe a to form two exhaust passages d1 and d2. A heat insulating gap e is provided between the pipe a and the outer pipe b. In many cases, the partition plate c has a continuous piece c1 welded from the outside by a laser, and a small curvature R is attached to the base of the partition plate c in contact with the continuous piece c1 so that it is easily deformed. Is absorbed.

The portion of the partition plate c on the flange f1 side is
Compared to the inner pipe a and the flange f1, the most contact is made with the hot exhaust gas and it is heated to a high temperature and the maximum thermal expansion occurs.
Since the partition plate c is welded to the hole of the flange f1 together with the inner pipe a to suppress the diametrical expansion, the partition plate c is buckled or deformed to form the exhaust passages d1 and d2. It may be changed, causing a discrepancy with the passage on the exhaust manifold side. Also, as the partition plate c is deformed, the continuous piece c1
Even if the welded part of the welder is displaced, the side of the inner pipe a cannot follow it, and the welded part may peel off, resulting in a seal failure.Furthermore, repeated bending load due to thermal expansion and contraction causes fatigue fracture of the welded part and the partition plate. Fatigue failure of c may occur. In either case, the output and torque of the engine are reduced.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to prevent the partition plate of the inner pipe from being deformed or buckled due to thermal expansion, or from fatigue fracture or damage due to repeated bending load due to exhaust pulsation or the like. And

[0005]

The first means for solving the above-mentioned problems is, as described in claim 1, that a diametrical partition plate is provided in the inner pipe to form two passages, and the inner pipe has a heat insulating gap. In the two-passage dual exhaust pipe in which the outer pipe is fitted via the outer pipe, a connecting portion for connecting to another member is formed at one end portion in the axial direction of the outer pipe, and a partition plate for the inner pipe inside the connecting portion. A clearance is provided between the outer circumference in the vicinity of the base of the outer tube and the inner circumference of the outer tube, and one end portion of the inner tube in the axial direction is joined and fixed to the outer tube.

As described in claim 2, the second solving means is, in claim 1, characterized in that a connecting member for connecting to another component is connected to the connecting portion.

A third solving means is, as described in claim 3, in claim 1 or 2, the inner pipe of the connecting portion is a perfect circle, and the outer pipe of the connecting portion has a major axis in the direction of the partition plate. It is characterized in that a clearance is formed between the inner tube and the outer tube as an ellipse.

A fourth solving means is, as described in claim 4, in claim 1 or 2, wherein the inner pipe of the connecting portion is
It is characterized in that the partition plate is formed into an elliptical or oval shape having a minor axis in the direction thereof, and the outer pipe of the connecting portion is formed into a perfect circle, and a clearance is formed between the inner pipe and the outer pipe.

[0009]

In each of the above-mentioned means, the partition plate expands the inner tube by thermal expansion larger than that of the inner tube, but since the partition plate is deformed within the clearance, the inner tube has less resistance to deformation and less stress.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a tube body of a two-passage dual exhaust pipe of the present invention, 2 is an inner pipe, 3 is an outer pipe, 4 is a partition plate, and the partition plate 4 allows the inner pipe 2 to have two exhaust pipes. It is divided into passages 2a and 2b. At the left end of the pipe body 1, the outer pipe 3 is reduced in diameter and overlaps the inner pipe 2 to form a small-diameter connecting portion 5. Then, a flange 6 is attached to the connecting portion 5.
Are fitted and welded to each other so that they can be connected to a flange provided at the collecting portion of the exhaust manifold (not shown). On the right end side of the tubular body 1, inward projections 7 and 8 are partially provided on the outer tube 3,
A spacer 9 made of metal mesh is inserted between the inner pipe 2 and the outer pipe 3 between the protrusions 7 and 8, and a heat insulating gap 10 is formed by the spacer 9 and the connecting portion 5 at the left end.

As is apparent from FIGS. 2 and 3, the inner pipe 2 and the partition plate 4 are formed of a single plate material, and the plate material is bent into an S-shape when viewed from the end face in the longitudinal direction, The semi-cylindrical portion, the flat surface portion, and the semi-cylindrical portion are continuous, and the narrow connecting pieces 11 are bent at both ends, and the connecting pieces 11, 11 are brought into close contact with both ends of the flat surface portion so that the base 4a of the partition plate 4 is welded. By joining together at 12, a perfectly circular inner tube 2 and a flat partition plate 4 are formed.

On the other hand, the outer tube 3 of the connecting portion 5 is formed into an elliptical shape having a reduced diameter, an inner diameter D1 in the direction of the partition plate 4 as a major axis, and an inner diameter D2 in a direction orthogonal to this as a minor axis. When fitted to the pipe 2, a clearance 1 is provided between the outer peripheral surface of the inner pipe 2 and the inner peripheral surface of the outer pipe 3 in the vicinity of the base 4a of the partition plate 4.
3 occurs, but the other portions are in close contact with each other and are fixed by the welded portions 14 provided on each side of the short diameter portion. The maximum clearance width C is set to a value that takes thermal elongation into consideration,
For example, if the inner diameter of the inner tube 2 is 66 mm, 0.55 to 0.7
It is set to 5 mm. The connecting portion 5 is inserted into the perfect circular insertion hole 6a of the flange 6 and welded, but the outer pipe 3 is welded to the flange 6 while maintaining the elliptical shape, and the outer diameter of the outer diameter of the outer pipe 3 is reduced. The gap between the insertion holes 6a of the flange 6 is sealed by welding. However, the clearance 13 remains and the partition plate 4
Makes it easier to heat. This clearance 13
Since it is extremely narrow, the amount of exhaust gas inflow is small, and the exhaust gas that has flowed in flows out to the catalytic converter.

When the engine operates, the exhaust gas is exhausted through the exhaust passage 2.
The semi-cylindrical surface of the inner pipe 2 is intermittently heated by flowing into a and 2b alternately, but the partition plate 4 is heated continuously from the front and back by the exhaust gas passing through the exhaust passages 2a and 2b and is heated most. The temperature becomes high, and the heat expands greatly in the width direction as compared with the inner tube 2 and the outer tube 3. As a result, the inner pipe 2 near the base 4a is pushed outward, but bends in the clearance 13, so that the resistance against thermal expansion of the partition plate 4 is small and the stress generated in the partition plate 4 or the root 4a is small. Buckling, deformation,
There is little risk of damage such as peeling.

In the embodiment shown in FIG. 4, the outer tube 3 is a perfect circle,
The inner tube 2 is an ellipse whose outer diameter D _{3 in the} direction of the partition plate 4 is smaller than the outer diameter D _{4 in the} direction orthogonal to this, and a clearance 13 is formed on the extension of the partition plate 4 as shown in FIGS. The same action as that of.

In the embodiment shown in FIG. 5, the vicinity of the root 4a of the partition plate 4 in the inner pipe 2 has a flat surface 15 and has an oval cross section, and the operation is the same as that of each of the above embodiments.

The shape of the outer tube at the connecting portion 5 is changed to the elliptical outer tube 3 shown in FIGS. 1 to 3, and the vicinity of the major axis portion of the ellipse shown in the figure has a slight step difference from other cylindrical portions. The large-diameter cylindrical surface may have a shape having a clearance corresponding to the step.

Two-passage double exhaust pipe 21 shown in FIGS. 6 and 7.
Includes an inner pipe 22 and an outer pipe 23, and the inner pipe 22 is a partition plate 4
Is divided into two exhaust passages 22a, 22b, and a heat insulating clearance 25 is formed between the inner pipe 22 and the outer pipe 23. The left side of the exhaust pipe 21 is the upstream part, and the outer pipe 23
A flange 26 is welded to the left end of the to form an exhaust pipe,
It can be connected to an exhaust manifold (not shown).

A ring-shaped reduced diameter portion 27 is provided at a portion of the outer pipe 23 slightly downstream of the flange 26, and the reduced diameter portion 27 is provided.
Is formed in close contact with the inner pipe 22 and holds the inner pipe 22 and the outer pipe 23. In the holding portion 28, the inner pipe 2
2 and the outer tube 23 are appropriately welded. Then, the holding portion 28 and the spacer 29 on the downstream side allow the heat insulating clearance 2
5 is formed, and an upstream clearance 25a having an open end is formed on the upstream side of the holding portion 28.

The two exhaust passages 22a and 22b are shown in FIG.
As shown in FIGS. 7A and 7B, a partition plate 24 can be formed by welding the inner pipe 22 having a circular cross section in the diameter direction, and FIG.
As shown in (d), one plate can be bent into an S-shape to make the circular pipe portion and the partition plate portion continuous, and the plate end can be welded to the partition plate portion.

When this exhaust pipe is connected to an exhaust manifold having two outlets, the partition plate 24 is heated continuously and alternately by the exhaust gas passing through the two exhaust passages 22a and 22b alternately, and intermittently. The temperature becomes higher than that of the heated cylindrical portion, and the front end side thereof becomes particularly high in temperature and thermally expands, so that the inner tube 22 is deformed into an elliptical shape by thermal expansion in the width direction. But,
Since the deformation of the inner pipe 22 is performed in the upstream clearance 25a, the restraining force does not act, and the partition plate 24 is deformed.
Since only the deformation resistance that the inner tube 22 is deformed into an elliptical shape by the thermal expansion of the partition plate 24 acts, the stress applied to the partition plate 24 is small and the risk of damage is small.

[0022]

As is apparent from the above description, according to the means of claims 1 and 2, there is a clearance between the vicinity of the base of the partition plate of the inner pipe and one end of the outer pipe. The heat expansion of the plate is hardly impeded, and the partition plate is effectively prevented from being damaged by the stress. Further, according to the means of claim 3, since the shape of the outer tube of the connecting portion is elliptical,
There is an advantage that it can be easily deformed from a circular cylinder and is easy to manufacture. According to the means of claim 4, since the outer pipe is a perfect circle, there is an advantage that welding with the flange becomes easy.
According to the means of claim 5, since there is a clearance between the inner pipe and the outer pipe on the side of the connection portion of the exhaust pipe, the thermal expansion of the partition plate is hardly impeded and the partition plate is prevented from being deformed. It has the effect of preventing damage due to stress.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention.

[Figure 2] Similarly, an end view

FIG. 3 is an enlarged view of part A of FIG.

FIG. 4 is an end view of another embodiment.

FIG. 5 is an end view of still another embodiment.

FIG. 6 is a vertical sectional view of an embodiment of the present invention.

7 (a) is a sectional view taken along line aa in FIG. 6, and (b) is b- in FIG.
Sectional view along line b, (c) and (d) are sectional views at the same positions as (a) and (b) in the modified example.

FIG. 8 is a conventional example of an exhaust pipe, in which (a) is a front view and (b) is
(a) bb line sectional view

[Explanation of symbols]

2,22 Inner pipe 3,33 Outer pipe 4,24 Partition plate 5 Connection part 6 Flange 10 Adiabatic gap 1 Continuously installed piece 12 Welded part 13,25a Clearance 28 Holding part

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Furuhashi 1 share at 508 Toyomachi, Hamamatsu, Shizuoka Yutaka Giken (72) Inventor Hiroto Yanagibayashi 1 share at 508 Toyomachi, Hamamatsu, Shizuoka Company Yutaka Giken (72) Inventor Kazuo Ishii 1-4-1 Chuo, Wako-shi, Saitama Prefectural Technology Research Institute (72) Inventor Takeshi Somura 4-1-1 Chuo, Wako-shi, Saitama Stock Company Honda Inside the Technical Research Institute (72) Inventor Masayuki Uekane 1-4-1 Chuo, Wako-shi, Saitama Co., Ltd. Within the Technical Research Institute of Honda (72) Inventor Yoshihiko Eguchi 1-4-1 Chuo, Wako-shi, Saitama Co., Ltd. In the laboratory (56) Reference JP-A-9-264128 (JP, A) Actual development Sho 53-35313 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F01N 7/08 F01N 7/14 F16L 9/18 F16L 59/06

Claims (4)

(57) [Claims] 1. An inner pipe is provided with a diametrical partition plate to form two passages, and an outer pipe is fitted to the inner pipe through a heat insulating gap.
In the passage double exhaust pipe, a connecting portion for connecting to another member is formed at one end portion in the axial direction of the outer pipe, and the inner periphery of the inner pipe of the outer pipe near the base of the partition plate and the inner portion of the outer pipe. A two-passage dual exhaust pipe, characterized in that a clearance is provided between the inner pipe and the outer pipe to join and fix one end portion in the axial direction of the inner pipe to the outer pipe. 2. The double-passage dual exhaust pipe according to claim 1, wherein a connecting member for connecting to another component is connected to the connecting portion. 3. The inner pipe of the connection portion according to claim 1 or 2, wherein the inner pipe of the connection portion is a perfect circle, and the outer pipe of the connection portion is an ellipse having a major axis in the direction of the partition plate. A two-passage dual exhaust pipe having a clearance. 4. The inner pipe of claim 1 or 2, wherein the inner pipe of the connecting portion is an ellipse or an oval shape having a minor axis in the direction of the partition plate, and the outer pipe of the connecting portion is a perfect circle. A two-passage dual exhaust pipe having a clearance formed between the pipes.