JP3284485B2 - Engine exhaust system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a first exhaust passage for guiding exhaust gas from an engine and a second exhaust passage such as an exhaust converter or a muffler.
The present invention relates to an engine exhaust device that connects an exhaust passage.

[0002]

2. Description of the Related Art For example, Japanese Unexamined Utility Model Publication No. Hei 3-25814 and Japanese Unexamined Utility Model Publication No. Hei 3-37230 have a plurality of exhaust passages and a flange formed with a plurality of through holes respectively corresponding to the exhaust passages. A first exhaust passage is known. It is necessary to further connect a second exhaust passage such as an exhaust converter and a muffler to such a first exhaust passage. Conventionally, however, the second exhaust passage is formed so as to cover each through hole on the downstream surface of the flange portion. And the outer peripheral surface at the end of the opening is welded to the downstream surface of the flange portion.

[0003]

However, if the upstream side opening of the second exhaust passage is simply welded to the flange of the first exhaust passage, the end of the opening and the flange are not welded. In some cases, a gap may be formed between the portion and the downstream surface of the portion, and if such a gap is formed, spatter generated by welding may enter the second exhaust passage. When the spatter enters the second exhaust passage as described above, for example, when welding an exhaust converter having a catalyst carrier therein as the second exhaust passage, the spatter is generated in the vent hole of the porous catalyst carrier in the exhaust converter. The problem of jamming occurs. Further, when the second exhaust passage is a muffler, the sputter is not discharged because it is hindered by the partition wall in the muffler, and the spatter remaining in the muffler collides with the wall surface of the muffler due to the exhaust gas flow or vibration, causing noise. Failure occurs.

Accordingly, the present invention has been made in view of the above-described problems, and is intended to prevent spatter from entering the second exhaust passage when welding a second exhaust passage such as an exhaust converter or a muffler to a flange portion of the first exhaust passage. The aim is to provide no exhaust system for the engine.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a first aspect of the present invention comprising a first exhaust port having a plurality of exhaust passages and a flange having a plurality of through holes corresponding to the exhaust passages. there is an exhaust passage, each on the downstream face of the flange portion
Abuts the upstream opening of the second exhaust passage so as to cover the through hole
And connecting the first exhaust passage and the second exhaust passage by welding, wherein the downstream surface of the flange portion surrounds the plurality of through holes and the inner peripheral surface of the upstream opening portion of the second exhaust passage. On the other hand, a step that protrudes closely over the entire circumference is protruded integrally,
And an outer peripheral surface of an upstream opening of the second exhaust passage and a flange portion
Characterized by being welded to the downstream surface .

[0006]

In the case where the second exhaust passage is welded by abutting against the surface of the first exhaust passage on the downstream side of the flange portion, spatter is generated in the second exhaust passage.
Even if an attempt is made to enter the exhaust passage, the stepped portion protruding from the flange portion is in close proximity to the inner peripheral surface of the second exhaust passage, so that spatter is generated between the inner peripheral surface of the second exhaust passage and the stepped portion. , So that spatter is prevented from entering the second exhaust passage.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 denotes a plate-like flange portion, and exhaust pipes 3a, 3b, 3c attached to an exhaust port of an engine (not shown) are connected to the flange portion 1. 1 and the exhaust pipes 3a, 3b, 3c form a first exhaust passage. An exhaust converter 2 serving as a second exhaust passage is welded to a surface on the downstream side of the flange portion 1 so that exhaust gas discharged through the exhaust pipes 3a, 3b, and 3c is collected in the exhaust converter 2. It is configured.
By the way, as shown in FIG. 2, through-holes 1a, 1 for inserting exhaust pipes 3a, 3b, 3c into the flange portion 1 respectively.
b · 1c are provided, and the exhaust pipes 3a · 3c are inserted into the through holes 1a · 1c respectively.
It is directly welded to the inner peripheral surface of c. On the other hand, since the exhaust pipe 3b is longer than the other exhaust pipes 3a and 3c, the amount of deformation due to thermal expansion is larger than the other exhaust pipes 3a and 3c. So the exhaust pipe 3
a bellows-like joint 31 to absorb the effect of thermal expansion
To connect the exhaust pipe 3b to the flange 1 by welding one end of the joint 31 to the outer periphery of the exhaust pipe 3b and welding the other end to the inner peripheral surface of the through hole 1b with the other end inserted into the through hole 1b. did.

On the other hand, the exhaust converter 2 is composed of a casing formed by joining a pair of half cases 21 and 22 and a catalyst carrier 24 sealed and held in the casing via a heat-resistant holding material 25. Be composed. Further, a base-like sensor port 23 for mounting an oxygen sensor for detecting the oxygen concentration in the exhaust gas, which is located on the upstream side of the catalyst carrier 24, is welded to one half case 21 in advance.

As shown in FIG. 3, the flange portion 1 is provided on the opposite side of the surface where the exhaust pipes 3a, 3b and 3c are inserted, ie, on the downstream side, with the upstream opening of the exhaust converter 2. The step portion 11 having the same shape as the peripheral surface 26 has the through holes 1a, 1b,
It protrudes so as to surround 1c. After the respective exhaust pipes 3a, 3b, 3c are welded and connected to the flange portion 1 as described above, the inner peripheral surface 26 of the exhaust converter 2 and the step portion 11 of the flange portion are connected as shown in FIG. The exhaust converter 2 is positioned with respect to the flange portion 1 so as to face each other. At this time, since the upstream opening of the exhaust converter 2 is fitted to the step portion 11, the positioning of the exhaust converter 2 with respect to the flange portion 1 can be performed accurately and easily. Then, the flange portion 1 and the outer peripheral surface of the opening end of the exhaust converter 2 are welded to each other in the positioned state. Even if spatter attempts to enter the exhaust converter 2 during this welding, the wall portion 11 facing the inner peripheral surface 26 serves as a barrier to prevent the intrusion of spatter. Further, when the casing is formed by joining the pair of half cases 21 and 22 as in the present embodiment, a gap is easily generated at the opening end side of the joint surface between the two half cases 21 and 22, and Converter 2
When welding the open end of the opening to the flange 1, spatter may enter the exhaust converter 2 from this gap. In this embodiment, however, this gap is hidden by the step 11 from the inside, so Intrusion of spatter can also be prevented.

In this embodiment, as shown in FIG. 3, the entire area surrounded by the step 11 of the flange 1 is made thicker than the peripheral edge of the flange 1. It is also possible to provide an annular projection having a predetermined width with the step portion 11 as the outer surface, so as to reduce the weight of the flange portion 1. As shown in FIG. 5, one surface of the plate-like flange portion is recessed by pressing to form a recess 12.
May be provided so that the step 11 is formed on the other surface to reduce the number of processing steps of the flange 1. In any case, all the through holes 1a, 1b, and 1c for the exhaust pipe are accommodated in a region surrounded by the step portion 11, and the step portion 11 serves as a kind of reinforcing rib, and the through holes 1a, 1b, and 1c.
The lowering of the strength of the flange portion 1 due to the formation of the adjacent portions 1c can be prevented. As a result, the through holes 1a, 1b, 1c
Can be reduced to reduce the size of the apparatus.

As shown in FIG. 3, in the above embodiment, the center of the large-diameter through-hole 1b connecting the bellows-shaped joint 31 is divided into two half cases 2 with respect to the centers of the other through-holes 1a and 1c.
Offset to two sides, half case 2 of flange 1
The through-holes 1a, 1b,.
1c were arranged so that the side edge L did not protrude toward the sensor port 23 side. This is because the insertion direction of the oxygen sensor (not shown) is set at a predetermined angle as shown in FIG.
3 must be attached to the inclined surface of the half case 21. At this time, if the side edge L is overhanging, the sensor port 23
Is difficult to weld to the half case 21.

Although the embodiment in which the exhaust converter 2 is welded to the flange portion 1 has been described above, the present invention is similarly applied to a case where another second exhaust passage such as an exhaust muffler is welded to the flange portion. it can.

[0013]

As is apparent from the above description, according to the present invention, since the flange is provided with the stepped portion, spatter enters the second exhaust passage when the second exhaust passage is welded to the flange. When the exhaust converter is welded as the second exhaust passage, the internal catalyst carrier is not clogged, and when the muffler is welded as the second exhaust passage, noise generated due to the collision of spatter with the inner wall of the muffler is reduced. Can be prevented. Further, since the strength of the flange is increased by this step, the mutual interval between the first exhaust passages can be narrowed and the entire exhaust device can be downsized.

[Brief description of the drawings]

FIG. 1 is a diagram showing an entire configuration of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II.

FIG. 3 is a sectional view taken along the line III-III.

FIG. 4 is a view showing details of a wall portion;

FIG. 5 is a view showing details of a wall portion in another embodiment.

FIG. 6 is a diagram showing details of a welding state of a sensor port.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flange part 2 Exhaust converter (2nd exhaust passage) 1a, 1b, 1c Through-hole 3a, 3b, 3c Exhaust pipe 11 Wall part 23 Sensor port 24 Catalyst carrier 31 Joint

Claims (1)

(57) [Claims] A first exhaust passage having a plurality of exhaust passage portions and a flange portion having a plurality of through holes respectively corresponding to the exhaust passage portions, wherein a first exhaust passage is provided on a downstream surface of the flange portion; Open the upstream opening of the second exhaust passage so as to cover each through hole.
An abutting surface for welding the first exhaust passage and the second exhaust passage, wherein the inner surface of the upstream side opening of the second exhaust passage surrounds the plurality of through holes on a downstream surface of the flange portion; A stepped portion facing and contiguous over the entire circumference is integrally formed, and the outer peripheral surface of the upstream opening of the second exhaust passage and the downstream surface of the flange are welded to each other. Engine exhaust system.