JP2000145445A - Exhaust manifold structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a welding state and improve airtightness and strength by forming a manifold body by bonding a manifold upper case and a manifold lower case, and forming an exhaust-collecting portion only in the manifold lower case. SOLUTION: A manifold body 28 is formed like a wafer by bonding a manifold upper case 28-1 and a manifold lower case 28-2 which are made of a sheet metal. An exhaust-collecting portion 26 is formed only in the manifold lower case 28-2. An end of the exhaust-collecting portion 26, i.e., an end 34 facing a pipe, has such a shape that is obtained by gathering the manifold lower case 28-2 at the center thereof. Thus, the exhaust-collecting portion 26 is formed only in the manifold lower case 28-2, and specifically; two separate sheet- members are not joined at the exhaust-collecting portion 26. Accordingly, roundness of the exhaust-collecting portion 26 is easily obtained. Moreover, a stable welding state can be obtained, whereby airtightness and strength can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust manifold structure for an internal combustion engine, and more particularly to an exhaust manifold structure for an internal combustion engine comprising a plurality of exhaust branch pipes and a manifold body provided with an exhaust manifold.

[0002]

2. Description of the Related Art In a multi-cylinder internal combustion engine of a vehicle,
An exhaust manifold is mounted on the cylinder head so that exhaust from each cylinder is led to an exhaust pipe. For this exhaust manifold, a plurality of exhaust branch pipes connected to the cylinder head and corresponding to the respective cylinders are provided, and a manifold body provided in an exhaust collecting section for combining exhaust flowing into each of the exhaust branch pipes is provided. It is configured.

[0003] Such an exhaust manifold structure for an internal combustion engine is disclosed, for example, in Japanese Utility Model Publication No. 8-7055. That is, as shown in FIGS. 9 and 10, the exhaust manifold 102 described in this publication is made of a sheet metal material and has a plurality of pipe-shaped exhaust branch pipes 104 and 10.
4, 104, 104 and these exhaust branch pipes 104, 10
A head-side mounting flange 106 for integrally mounting one end of each of the four, 104, 104 to a cylinder head (not shown) and one end of each of a pair of exhaust branch pipes 104, 104 on both sides are assembled. And a pair of exhaust branch pipes 10 on the center side.
The other exhaust manifold 108-2 having a forked shape that collects the other end of each of the exhaust manifolds 4 and 104;
And a pipe-side mounting flange 110 that integrally connects the other exhaust collecting part 108-1 to an exhaust pipe (not shown). Since the exhaust collecting section 108 connects the plurality of exhaust branch pipes 104 collectively, the exhaust collecting section 10
It is difficult to simply form 8 with a pipe,
For this reason, the two plate members 112-1 and 112-2 formed in two along the axial direction face each other, and the respective side portions 112-1 of the plate members 112-1 and 112-2 are opposed to each other.
a, 112-2a are fixed by side welds 114 to form the exhaust collecting part 108, and FIG.
As shown in FIG. 11, the pipe-side end portion 1 of the exhaust collecting portion 108
16 is inserted into a collecting portion mounting hole 118 having an inner diameter d formed in the pipe-side mounting flange 110 and welded by a flange-side welding portion 120 from the outside, so that the pipe-side end portion 116 of the exhaust collecting portion 108 is connected to the pipe-side mounting portion. The flange 110 is fixed. In such a case, as shown in FIG. 11, a stress concentration portion X of stress and thermal stress due to engine vibration exists at the boundary between one side of the flange side welded portion 120 and the outer surface of the pipe side end portion 116. A first heat affected zone Y-1 by welding exists at the pipe side end portion 116 near the stress concentration portion X, and the pipe side mounting flange 110 and the pipe side end portion 11 near the other side of the flange side welded portion 120.
At 6, there is a second heat affected zone Y-2 due to welding. The heat affected zones Y-1 and Y-2 are portions where the base metal strength is reduced due to the influence of welding heat.

[0004] The exhaust manifold structure of an internal combustion engine is disclosed in, for example, Japanese Patent Application Laid-Open Nos. 10-89064 and 9-280045. JP Hei 10
The exhaust manifold described in JP-A-89064 is constituted by three sheet metal members of a front half, a partition, and a back half, and the exhaust manifold is formed by a front half and a back half. It was done. Japanese Unexamined Patent Publication No. 9-280045 discloses a joint for welding by a pair of outer edges of upper and lower halves of a steel plate manifold body which are located on outermost sides in the arrangement direction of branch pipes and are opposed to each other. On the other hand, a stepped lap joint for welding is constituted by the insides of the upper and lower halves facing each other facing the gap between the adjacent branch pipe portions.

[0005]

However, conventionally, in the exhaust manifold 102 as shown in FIGS. 9 and 10, the exhaust collecting portion 108 is divided into two plate members 112-1 and 112.
-2, the pipe-side end portion 116 of the exhaust collecting portion 108 and the pipe-side mounting flange 110 are welded and fixed from the outside, and the exhaust collecting portion 10
8 has two plate members 112-1 and 112-2 formed in a shape divided into two along the axial direction, facing each other. The clearance from the inner diameter d of the mounting hole 118 is not stable, so that it is difficult to obtain a stable welding state, and there is a disadvantage that airtightness is impaired.

Further, as shown in FIG.
Pipe side end part 116 and pipe side mounting flange 110
In the lap welding portion 120a which is a part of the flange-side welded portion 120 for fixing the welded portion, the welded portion between the side welded portion 114 of the exhaust gas collecting portion 108 and the flange-side welded portion 120 is a seam between the welds. In addition, it is difficult to obtain a stable welding state, whereby the airtightness is impaired, and the two-part welding is greatly affected by the heat.

[0007]

Therefore, in order to eliminate the above-mentioned disadvantages, the present invention provides a plurality of exhaust branch pipes connected to the cylinder head of a multi-cylinder internal combustion engine and corresponding to each cylinder. In an exhaust manifold structure of an internal combustion engine provided with a manifold body provided with an exhaust collecting part for combining exhaust flowing into each exhaust branch pipe, the manifold body is joined to a manifold upper case and a manifold drawer case, and the exhaust gas is formed. The assembly part is formed only in the manifold drawer case.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, the manifold body is constituted by a manifold upper case and a manifold drawer case, and the exhaust gathering portion is formed only in the manifold drawer case. Therefore, even if the mounting flange is fixed to the exhaust collecting part, the roundness is impaired, and the seam between the welds is lost, so that a stable welding state can be obtained.
Thereby, airtightness and strength can be improved.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; 1 to 7 show a first embodiment of the present invention. 6 and 7, 2 is a vehicle,
4 is a multi-cylinder (4-cylinder) internal combustion engine, 6 is a transmission, 8 is a radiator, 10 and 10 are front wheels, and 12 and 1
2 is a rear wheel.

A cylinder head (not shown) of the internal combustion engine 4
, An exhaust manifold 14 made of sheet metal is attached. The exhaust manifold 14 has a first exhaust pipe 16-1.
, A second exhaust pipe 16-2 and a third exhaust pipe 16-3 are sequentially and sequentially provided. The first to third exhaust pipes 16-1
The catalyst 18, the sub-chamber 20, and the main chamber 22 are provided in the middle of ~ 16-3.

In the exhaust manifold 14, a plurality of pipe-shaped exhaust branch pipes 24, 24, 24, 24 connected to the cylinder head to form a plurality of exhaust branch passages (not shown) corresponding to each cylinder. And an exhaust collecting section 2 that combines exhaust flowing into each exhaust branch pipe 24.
6 is provided.

A head-side mounting flange 32, which is mounted on the cylinder head, is fixed to each head-side end portion 30 on one end side of each exhaust branch pipe 24 on the cylinder head side. Further, a pipe-side mounting flange 36 for attaching the first exhaust pipe 16-1 is fixed to a pipe-side end portion 34 which is an end portion of the exhaust collecting portion 24.

In the manifold body 28, a so-called Monaca type is formed by joining a manifold upper case 28-1 and a manifold drawer case 28-2 made of sheet metal, and exhaust is performed only in the manifold drawer case 28-2. An aggregation 26 is formed. That is, this exhaust collecting part 2
6 has a volume substantially formed only by the manifold drawer case 28-2, and the remaining part of the opening is closed by the manifold upper case 28-1. The connection port to the main exhaust pipe connected to the exhaust collecting section 26 is formed only in the manifold drawer case 28-2.

That is, in the manifold upper case 28-1, as shown in FIGS.
Upper connecting portions 38 for connecting the upper halves of the other ends of the
The upper part is provided with a sensor mounting boss 40 and a pair of main body side cover mounting brackets 42.

Further, in the manifold drawer case 28-2, as shown in FIGS.
8, each lower-side connecting portion 44 for connecting the lower half of each other end of each exhaust branch pipe 24 is formed, and the exhaust collecting portion 26 is formed downward with a required space. Have been.

The manifold upper case 28-1 and the manifold drawer case 28-2 are integrally fixed at their peripheral edges by welding at side welds 46, and the other ends of the exhaust branch pipes 24 are integrated. Connect the sides.

As shown in FIG. 4, a pipe-side end portion 34, which is an end portion of the exhaust collecting portion 26, has a shape in which the position of the center C of the manifold drawer case 28-2 is narrowed, that is, the outer diameter D1 of the other portion. Is formed to have a small outer diameter D2, and is inserted into the collecting portion mounting hole 48 of the inner diameter D3 formed in the pipe-side mounting flange 36.

As shown in FIG. 4, the pipe-side end portion 34 of the exhaust collecting portion 26 and the pipe-side mounting flange 36 are connected to the pipe-side end portion 3 of the manifold drawer case 28-2.
4 is fixed by welding at the flange side welded portion 50 from the inside of the opening.

1, 3 and 5, reference numeral 52
52 is a pair of flange side cover mounting brackets, and 54 is an EGR pipe provided on the head side mounting flange 32 and one exhaust branch pipe 24.

Next, the operation of the first embodiment will be described.

Exhaust gas from each cylinder of the internal combustion engine 4 is merged from each exhaust branch pipe 24 at an exhaust collecting section 26, guided from the first to third exhaust pipes 16-1 to 16-3, and discharged to the outside. I do.

Incidentally, in the manifold body 28 of the first embodiment, the manifold upper case 2 made of sheet metal is used.
8-1 and a manifold drawer case 28-2, and the exhaust collecting portion 26 is formed only in the manifold drawer case 28-2, and the pipe-side end portion 34 of the exhaust collecting portion 26 of the manifold drawer case 28-2. Is squeezed to the center C side and the pipe side mounting flange 36 from the inside.
And are fixed by welding. As a result, as shown in FIG. 4, a stress concentration portion A-1 due to engine vibration exists at the boundary between the pipe-side mounting flange 36 and the outer surface of the pipe-side end portion 34 of the exhaust gas collecting portion 26. Part 50
Is located at the boundary between the first side and the inner surface of the pipe-side end portion 34 of the exhaust collecting portion 26. Further, a stress concentration portion A-2 due to heat exists. A first heat-affected zone B-1 exists in the pipe-side end portion 34 between the pipe-side mounting flange 3 and the gathering-portion mounting hole 48 on the other side of the flange weld 50.
6 has a second heat affected zone B-2.

As a result, the exhaust collecting part 26 is formed only in the manifold drawer case 28-2, and the plate material divided in the exhaust collecting part 26 is not combined. , Pipe side mounting flange 3
6 stabilizes the clearance with the inner diameter D3 of the gathering portion mounting hole 48, and eliminates the seam between the welds, so that a stable welding state can be obtained, thereby improving the airtightness, Strength can be improved.

Further, the pipe side end portion 3 of the exhaust collecting portion 26
Since it is inserted into the collecting portion mounting hole 48 with the shape of 4 narrowed, the thermal stress generated by the thermal expansion acting on the exhaust collecting portion 26 can be absorbed, and the durability can be improved.

Further, the pipe-side end portion 3 of the exhaust collecting portion 26
4 and the pipe-side mounting flange 36 are welded from the inside, so that the stress concentration portion A-1 generated by engine vibration and the stress concentration portion A-2 due to heat are separated from each other.
Each stress can be dispersed, and the durability can be improved.

FIG. 8 shows a second embodiment of the present invention.

In the second embodiment, parts having the same functions as those in the first embodiment are denoted by the same reference numerals.

The features of the second embodiment are as follows. That is, the manifold main body 28 is configured by joining a manifold upper case 28-1 having an upper inclined joint surface 28-1a and a manifold drawer case 28-2 having a lower inclined joint surface 28-2a. Further, the manifold upper case 28-1 is formed with a circular branch pipe connecting portion 56 into which the entire other end of each exhaust branch pipe 24 is inserted. Also, the manifold drawer case 28-
In No. 2, an exhaust collecting part 26 was formed.

According to the structure of the second embodiment, since the branch pipe connecting portion 56 for connecting the other ends of the exhaust branch pipes 24 is not divided into upper and lower portions, a welding portion from the side is unnecessary. Also, the airtightness and strength can be improved on each exhaust branch pipe 24 side.

[0030]

As is apparent from the above detailed description, according to the present invention, the manifold body is formed by joining the manifold upper case and the manifold drawer case, and the exhaust collecting portion is formed only in the manifold drawer case. Even if the mounting flange is attached to the exhaust collecting portion, the roundness is impaired, the seam between the welds is eliminated in the exhaust collecting portion, a stable welding state can be obtained, and the airtightness and strength can be improved.

[Brief description of the drawings]

FIG. 1 is a front view of an exhaust manifold.

FIG. 2 is a partial sectional view from the left side of the exhaust manifold of FIG. 1;

FIG. 3 is a plan view of the exhaust manifold of FIG. 1;

FIG. 4 is an enlarged view according to arrow 〓 of FIG. 2;

FIG. 5 is a perspective view of an exhaust manifold.

FIG. 6 is a side view of the vehicle.

FIG. 7 is a bottom view of the vehicle of FIG. 6;

FIG. 8 is a sectional view of an exhaust manifold according to a second embodiment.

FIG. 9 is a front view of a conventional exhaust manifold.

FIG. 10 is an exploded view of the exhaust collecting section in FIG.

FIG. 11 is a diagram illustrating a stress concentration portion in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 2 Vehicle 4 Internal combustion engine 14 Exhaust manifold 16 Exhaust pipe 24 Exhaust branch pipe 26 Exhaust collecting part 28 Manifold main body 34 Pipe side end part 48 Collecting part mounting hole 50 Flange side welding part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akira Mamoru Watari 1069 Toyatsuka-cho, Isesaki-shi, Gunma F-term in Gunma Works, Sankei Giken Co., Ltd. 3G004 BA05 DA02 DA12 GA02 GA04 GA06

Claims (3)

[Claims] 1. A plurality of exhaust branch pipes connected to a cylinder head of a multi-cylinder internal combustion engine and corresponding to each cylinder are provided.
In an exhaust manifold structure of an internal combustion engine provided with a manifold body provided with an exhaust collecting part for combining exhaust flowing into each exhaust branch pipe, the manifold body is joined to a manifold upper case and a manifold drawer case, and the exhaust gas is formed. An exhaust manifold structure for an internal combustion engine, wherein a collecting portion is formed only in the manifold drawer case. 2. An end portion of the exhaust manifold formed on the manifold drawer case to which a mounting flange is attached,
2. An exhaust manifold structure for an internal combustion engine according to claim 1, wherein said manifold drawer case is formed in a shape narrowing a center position. 3. An end portion of the exhaust collecting portion to which the mounting flange is mounted, and the mounting flange are fixed by welding from an inside of an end portion opening of the manifold drawer case. Exhaust manifold structure of internal combustion engine.