JPH0364616A - Exhaust manifold for multi-cylinder engine - Google Patents

Abstract

PURPOSE:To shorten each branch passage section in length by forming the branch passage section of an exhaust manifold by means of joining divided molding members while the both sides of the major axis of an opening section described later is made to be a junction line in the side surface of an engine formed with the opening sections of respective exhaust ports, each of which is in a non-circular shape. CONSTITUTION:Exhaust ports 2 through 5 for respective cylinders 1 (1a through 1d) are communicated with port opening sections 2b through 5b each of which is in a non-circular shape and is opened to the side surface of an engine main body E, at their downstream ends wherein an exhaust manifold 7 is connected with said opening sections 2b through 5b. The exhaust manifold section 7 is made up out of No.1 through No.4 branch passage sections 9a through 9d communicated with the respective port opening sections 2b through 5b, a junction section 10 and of the like. In this case, No.2 and No.3 branch passage 9b and 9c, and the junction section 10 are formed by means of joining a front and a rear member 17 and 18 which are divided into both sides along the major axes of the opening sections 2b through 5b, and No.1 and No.4 branch passage section 9a and 9d are concurrently formed by means of widening and bending a pipe section member 21.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust manifold for a multi-cylinder engine such as a four-cylinder engine.

(Prior Art) Conventionally, in some multi-cylinder engines, the opening of the exhaust port in the engine body is not circular, but is formed in a non-circular shape such as an oval or an ellipse. For connecting the exhaust manifold to
The shape of the connecting portion of the branch pipe of the exhaust manifold must also be non-circular in accordance with the above-mentioned opening shape.

In particular, in an engine in which a plurality of exhaust valves are installed for each cylinder of the engine to increase exhaust efficiency, the opening shape of the exhaust port is non-circular. In addition, a technique for reducing weight by forming a branch pipe connected to the above-mentioned non-circular opening using a vibrator is disclosed, for example, in Japanese Patent Laid-Open No. 83-17.
This is known as seen in Japanese Patent No. 0515.

(Problem to be Solved by the Invention) However, when forming an exhaust manifold by bending the vibrator member as described above, a certain amount of pipe length is required to carry out the bending process. This increases the size of the exhaust manifold, which becomes an obstacle when trying to make the engine more compact.

In other words, in order to expand a circular vibrator as a raw material into a non-circular shape, bend it to deform it toward a gathering part, etc., a predetermined length is required to grasp the material in each process. If the length required for these is secured, the distance from the boat opening to the gathering part becomes longer, making the exhaust manifold larger, and at the same time, the engine becomes larger as it moves away from the side of the cylinder head.

In addition, normally, it is better to connect the branch passage part of the exhaust manifold to the gathering part in a circular shape rather than in a non-circular shape in terms of sealing performance and workability. It is difficult to do so and goes against the demands for compactness and cost reduction.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide an exhaust manifold for a multi-cylinder engine in which it is easy to form a non-circular passage and the length of the branch passage to the gathering part can be shortened. It is.

(Means for Solving the Problems) In order to achieve the above object, the exhaust manifold of the present invention has a non-circular opening of the exhaust port on the side surface of the engine body, and a branch of the exhaust manifold connected to the exhaust port. The passage portion is formed by joining separate molded members with joining lines on both sides of the long axis of the exhaust port opening.

In addition, in a four-cylinder engine in which the exhaust port opening is formed in an oval shape that is long in the direction of the cylinder row, the branch passage of the exhaust manifold that connects to the exhaust ports of the second and third cylinders is connected to the exhaust port opening. A branch passage section of the exhaust manifold that connects to the exhaust ports of the first and fourth cylinders is formed by molding the vibe members. It is composed of a collection of branch passages.

(Function) In the above-mentioned exhaust manifold, the branch passage section that connects to the non-circular opening of the exhaust port is formed by joining together the split molded members, and the length of the branch passage section can be easily formed. It is possible to shorten the length, and the structure is compact and easy to hang.

In particular, in a 4-cylinder engine, compactness is achieved by combining the branch passages of the second and third cylinders, which have a short distance to the converging part, while the distance between the first and fourth cylinders is a certain distance. Therefore, it is advantageous in terms of productivity and cost to form the branch passage portion with a vibrator member.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the planar structure of the exhaust manifold, FIG. 2 shows the front structure, and FIG. 3 shows the cross-sectional side structure.

The cylinder head (shown by imaginary lines) in the engine body E of an in-line four-cylinder engine has the first to fourth cylinders 1 inside.
Equipped with a to ld (combustion chamber), exhaust gas flows from exhaust port 2 to
Exhausted by 5. In the exhaust ports 2 to 5 of each cylinder 1a to 1d, valve opening portions 2a to 5a to each combustion chamber are respectively opened and closed by two exhaust valves (not shown), and both valve opening portions 2a of each cylinder 1a to 1d are opened and closed by two exhaust valves (not shown). 5a join together, and their downstream ends communicate with boat openings 2b to 5b opened on the side surface of the engine body E (cylinder head). The port openings 2b to 5b are formed in a horizontally long non-circular shape (ellipse) long in the cylinder row direction, and are arranged in parallel in the order of the first cylinder 1a to the fourth cylinder 1d.

An exhaust manifold 7 is fastened to the side surface of the engine body E, which communicates with the port openings 2b to 5b of the exhaust ports 2 to 5 of the cylinders 1a to 1d, and collects the port openings 2b to 5b to discharge exhaust gas downstream. Ru. The exhaust manifold 7 includes a fastening flange 8 fastened to the engine body E, and first to fourth branch passages 9 communicating with the respective port openings 2b to 5b.
a to 9d, a gathering part 10 that gathers the branch passage parts 9a to 9d approximately in the center, and a connecting flange 11 connected to the gathering part 10 and connected to a downstream exhaust pipe (not shown). has been done.

port openings 3b of the second cylinder lb and the third cylinder 1c;
4b, second and third branch passage sections 9b, 9c connected to
The cross section is approximately elliptical in the vicinity of the port openings 3b and 4b, and the cross section changes to a circular shape while bending from both side port portions toward the center, and both branch passage portions 9b and 9c converge, and the cross section becomes oblique. It is bent downward and extends downward, and is configured to communicate from above with a gathering part 10 in which a volume chamber 12 is formed.

On the other hand, the first and t? 54 branch passage portions 9a, 9d have an elliptical cross section near the port openings 2b, 5b, respectively bend toward the center and change to a circular cross section, and further bend downward and curve toward the center. The downstream end is connected to the gathering part 10 so as to join from both sides.

The fastening flange 8 has non-circular (elliptical) first to fourth inlet ports 13a to 13d corresponding to the shapes of the port openings 2b to 5b formed in a plate member having a predetermined thickness, and has a circumferential edge. A bolt hole 14 for tightening is provided in the part. In addition, a window-shaped cutout hole 15 is formed in the portion between the cylinders of the introduction ports 13a to 13d for weight reduction.

Further, as shown in FIG.
It is formed by joining a front member 17 and a rear member 18, which are divided on both sides along the long axis of the elliptical shape of 5b. The front member 17 and the rear member 18 are formed by pressing a plate material into a half-split shape along the shapes of the branch passage parts 9b, 9c and the gathering part 10, and have seam parts 17a, 18a extending on both sides of the joining line. The fitting process is performed by welding. Further, the collecting portion 10 is connected to the first and fourth cylinders 1 on both sides.
Branch passage section 9a for a, ld.

Circular communicating holes 10a and 10b to which the connecting holes 9d are connected, and a communicating opening 10C for the connecting flange 11 at the bottom thereof are formed by the above-mentioned alignment process.

The upstream ends of the second and third branch passage parts 9b and 9c formed by the above-described alignment process are fixed to the fastening flange 8, and the seam parts 1 on both sides of the upstream ends are fixed to the fastening flange 8.
7a, 18a are removed, the ends of the passages 9b, 9c protrude in a cylindrical shape, and the cylindrical protrusions are inserted into the second and third introduction ports 13b, 13C of the fastening flange 8, and the cylindrical protrusions The tips of the sections and the inner circumferential surfaces of the introduction ports 13b and 13C are welded together.

Furthermore, as shown in FIG. 5, the seam portions 17a and 18a are formed so that the seam portion 17a of the front member 17 is narrower than the seam portion 18a of the rear member 18, and the formation of this stepped portion facilitates welding work. This allows for a large welding area. Further, the front part of the gathering part 10 is bulged forward, and one part is formed for mounting the 02 sensor 20.

Next, the first and fourth branch passage portions 9a and 9d are formed by expanding and bending the pipe member 21 to change the cross-sectional shape and bend the pipe member 21, and the non-circular upstream end 21a of the pipe member 21 is They are inserted into the first and fourth introduction ports 13a and 13d of the fastening flange 8, respectively, and the insertion tips and the inner circumferential surfaces of the introduction ports 13a and 13d are welded together. Further, the circular downstream end 21b of the pipe member 21 is a communication port 10a that is open on both sides of the gathering portion 10.

10b, and the periphery of the opening end and the outer periphery of the vibrator member 21 are welded and joined.

Further, in the connection flange 11, a circular exhaust gas outlet 22 is opened at the center of the substantially triangular flange portion 11a, and fastening bolts 23 are installed at each top. Further, as shown in FIG. 4, a sleeve 11b is fixed to the exhaust gas outlet 22 of the flange portion 11a and protrudes upward, and the tip of the sleeve 11b is connected to the collecting portion 10.
The entire exhaust manifold 7 is constructed by inserting the exhaust manifold into the communication port 10c that opens downward, and welding the exhaust manifold 7 while adjusting the height.

The height of the connecting flange 11 at the downstream end can be adjusted when the front attachment 17 is adjusted when the connecting portions of the second and third branch passages 9b and 9c with the inlets 13b and 13C to the fastening flange 8 are aligned. The precision of the pressing of the rear member 18 absorbs the error in the connection position that occurs in the connection flange 11 on the downstream side, thereby ensuring the precision of the connection with the exhaust pipe. In addition, the above-mentioned height adjustment sleeve 1
If a gap is created between the insertion end of the insertion portion 1b and the circumferential surface of the communication port 10C of the insertion portion, gas will flow into that portion and reliability will decrease.
The upper end and lateral communication hole 10a of the cylindrical part forming the
10b, and is located lower than the lower end of the first. Fourth branch passage section 9
It is formed so that the exhaust gas from a and 9d flows smoothly down.

In addition, each branch passage portion 9 in the exhaust manifold 7
Attachment fittings 24 for attaching an insulator as a heat insulating member are provided on the front side and back side of a to 9d and the gathering portion 10.

According to the embodiment described above, the exhaust manifold 7 for a four-cylinder engine is connected to the collecting part 1 for the second and third branch passage parts 9b and 9C, which have short distances to the collecting part 10.
0, the front member 17 and the rear member 18 are formed by press molding, and it is easy to form a non-circular shape on the inflow side, and the integral formation of both can be made compact. Further, the first and fourth branch passage sections 9a and 9d have a long distance to the gathering section 10, and can be formed by the pipe member 21, thereby improving productivity and reducing costs.

Further, the branch passage portions 9a to 9d are assembled from above on the upstream side of the 2.3 branch passage portions 9b and 9c for the 2.3 cylinders lb and lc, and then the 1.4 cylinders 1a and 1c are assembled from above.
By merging the 1.4th branch passage parts 9a and 9d from the side, the volume chamber 12 of the gathering part 10 becomes smaller, and furthermore, the ignition order of the second cylinder 1b and the third cylinder IC is not consecutive. Therefore, even if the second and third branch passage portions 9b and 9c are merged quickly, the exhaust pressure will not increase.

Furthermore, an 02 sensor 20 is installed at the gathering section 10, and since the volume chamber 12 as an internal space of the gathering section 10 is narrow, it is possible to detect the averaged air-fuel ratio in each cylinder 1a to 1d. In addition, the exhaust gas temperature to the catalyst device is high, and good reaction purification performance can be obtained.

In addition, the second and third branch passage portions 9b are formed by the above-mentioned alignment process.
, 9c and the front member 17 and rear member 18 that form the gathering portion 10, the thickness of the front member 17, which has a high thermal load, is set to 2.
The rear member 18 has a thickness of 0 mm and has a smaller heat load.
The plate thickness may be set to 1.5 mri to reduce weight.

In addition, the pipe member 21 forming the first and fourth branch passages 9a and 9d may be formed integrally as in the embodiment, or if the expansion rate of the non-circular portion near the fastening flange is large, the pipe member 21 may have a different diameter. The member may be divided into two parts, one on the gathering part side and the other on the fastening flange side, and then connected.

(Effects of the Invention) According to the present invention as described above, the branch passage portion of the exhaust manifold connected to the non-circular opening of the exhaust port to the side surface of the engine body is arranged so that the branch passage portion of the exhaust manifold is connected to the non-circular opening of the exhaust port on the side of the engine body. By forming the joining line by joining the split molded members, it is possible to easily form a non-circular cross-section, and the length of the branch passage can be shortened, making it possible to construct a compact exhaust manifold. be.

In addition, in a 4-cylinder engine, the branch passages of the 2nd and 3rd cylinders, which have a short distance to the converging part, are combined by machining to achieve compactness, while the 1st and 4th cylinders have a certain distance. Therefore, by forming the branch passage portion with a pipe member, it is possible to improve the productivity and cost of the exhaust manifold as a whole.

[Brief explanation of drawings]

FIG. 1 is a plan view of an exhaust manifold according to an embodiment of the present invention, FIG. 2 is a front view thereof, FIG. 3 is a cross-sectional side view taken along the line ■-■ in FIG. 2, and FIG. 4 is a f? A cross-sectional view along the IV-IV line in Figure S1, Figure 5 is the 1st
It is a cross-sectional end view along the VV line of a figure. E...Engine body, 1a to 1d...
Cylinder, 2-5...Exhaust port, 2b-5b...
... Port opening, 7 ... Exhaust manifold, 8 ... Fastening flange, 9a to 9d ...
... Branch passage section, 10... Gathering section, 11...
... Connection flange, 12 ... Volume chamber, 13a
~13d...Introduction port, 17...Front member, 18...Rear member, 17a, 17b...
- Seam part, 21...Pipe member.

Claims (2)

[Claims] (1) In a multi-cylinder engine in which the exhaust port opening opens in a non-circular shape on the side of the engine body, the branch passage section of the exhaust manifold connected to the exhaust port joins both sides of the long axis of the exhaust port opening. An exhaust manifold for a multi-cylinder engine, characterized in that it is formed as a wire by joining together split molded members. (2) In a four-cylinder engine in which the exhaust port opening is formed in an oval shape extending in the direction of the cylinder row, the branch passage section of the exhaust manifold connected to the exhaust ports of the second and third cylinders has the exhaust port opening. The branch passage section of the exhaust manifold, which is connected to the exhaust ports of the first and fourth cylinders, is formed by molding the pipe members. An exhaust manifold for a multi-cylinder engine characterized by a collection of branch passages.