JP2001065340A - Exhauster of straight four-cylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhauster of a straight four-cylinder engine easy to manufacture, low in cost and simple in structure. SOLUTION: This is an exhauster 15 constituted of an exhaust manifold 17 having branch pipes 27, 29, 31, 33 connected to an exhaust port of a straight four-cylinder engine and a front tube 19 connected to it, the exhaust manifold 17 is constituted of an outside cylinder 25 forming a pair of half split outside cylinders 21, 23 which are stamped by wafering them and connected to the exhaust port of the engine and an inside cylinder 26 arranged in the outside cylinder 25 and welding an exhaust gas introduction port on an inner periphery of the branch pipes 29, 31 of the outside cylinder 25 connected to second and third exhaust ports, and an upstream part of the front tube 19 is structured in a double pipe of an outer pipe 53 to be connected to the outside cylinder 25 and an inner pipe 55 connected to the inside cylinder 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exhaust device for an in-line four-cylinder engine.

[0002]

2. Description of the Related Art In general, a vehicle exhaust system is provided with an exhaust manifold for collecting exhaust gas discharged from an engine into a single body and sending the exhaust gas to a downstream side. As disclosed,
2. Description of the Related Art Recently, many vehicles are equipped with an exhaust manifold (pipe exhaust manifold) using a plurality of metal pipes.

FIG. 4 shows an exhaust manifold of this type which is mounted on an in-line four-cylinder engine. In the figure, reference numerals 1 to 4 denote three-dimensionally bent metal pipes.
4 are connected to the head flange 5 respectively, and the head flange 5 is bolted to the cylinder head so that each of the pipes 1 to 4 communicates with the exhaust port of the engine.

[0004] Each of the pipes 1 to 4 is designed to have the same length as much as possible because it is preferable for the back pressure to be equal. Further, the downstream side of each of the pipes 1 to 4 is connected to a collecting pipe 6, and a front tube 9 is connected to the collecting pipe 6 via flanges 7 and 8, as shown in FIG. A partition wall 10 made of one sheet material is welded to the upstream portion of the front tube 9 to divide the exhaust gas passage into two, and the pipes 1 and 4 connected to the exhaust ports 1 and 4 are connected to one of the front tubes 9. Exhaust gas channel 9a
An exhaust device 11 is known in which pipes 2 and 3 connected to the second and third exhaust ports are opened in the other exhaust gas passage 9b to prevent exhaust interference.
Although it depends on the displacement of the engine, it is generally considered preferable to provide an exhaust gas collecting portion in the front tube 9 at a distance of 700 to 800 mm from the cylinder head from the viewpoint of measures against back pressure.

[0005]

However, in the conventional exhaust device 11 including the exhaust manifold 13 and the front tube 9, since the pipes 1 to 4 are designed to be as long as possible in a small space, The exhaust manifold 13 is manufactured by performing complicated three-dimensional processing on the pipes 1 to 4. As a result, it has been pointed out that the manufacturing cost is increased due to the complicated processing.

When welding a partition 10 made of a single plate to the upstream portion of the front tube 9, as a countermeasure for displacement during welding, a substantially Z-shaped cross section as shown in FIG. However, since such a plate material has an uneven strength, if a force is applied in the vertical direction during the bending process of the front tube 9, the partition wall 10 may be buckled.

The present invention has been devised in view of the above circumstances, and has as its object to provide an exhaust system for an in-line four-cylinder engine which is easier to manufacture and lower in cost than the conventional one and has a simple structure.

[0008]

In order to achieve the above object, an invention according to claim 1 is provided with four branch pipes mounted on a cylinder head of an in-line four-cylinder engine and connected to each exhaust port of the engine. An exhaust manifold having
An exhaust device for an in-line four-cylinder engine comprising a front tube connected to the exhaust manifold, wherein the exhaust manifold is formed by centering a pair of half-cut outer cylinders formed by pressing a metal plate. An outer cylinder having four branch pipes connected to the respective exhaust ports, and an exhaust gas inlet provided in the outer cylinder and having an exhaust gas introduction port formed on the inner circumference of the branch pipe connected to the second and third exhaust ports. Exhaust gas discharged from the first and fourth exhaust ports flows down in the outer cylinder, and exhaust gas discharged from the second and third exhaust ports flows in the inner cylinder. And the upstream portion of the front tube has a double tube structure composed of an outer tube and an inner tube. The outer tube is connected to the outer tube, and the inner tube is connected to the inner tube of the front tube. Are connected.

The invention according to claim 2 is the invention according to claim 1.
In the described exhaust device of the in-line four-cylinder engine, the inner cylinder is
The invention according to claim 3 is characterized by comprising a pair of half-split inner cylinders formed by pressing a metal plate. In the exhaust system for an in-line four-cylinder engine according to claim 1, the inner cylinder is made of a metal pipe. It is characterized by consisting of. According to a fourth aspect of the present invention, there is provided an exhaust system for an in-line four-cylinder engine according to any one of the first to third aspects.
The distance from the cylinder head to the confluence of the exhaust gas discharged from the No.
The distance from the cylinder head to the confluence of the exhaust gas discharged from the numbered exhaust port in the inner cylinder is substantially equal in length.

(Effect) According to the exhaust system of each claim, the exhaust gas sequentially discharged from the first and fourth exhaust ports as the engine is driven flows into the outer cylinder from the branch pipe. The gas flows down the outer tube of the outer tube and the front tube while merging at the gap formed between the inner tube and the outer tube. Flow down the inner tube of the front tube.

[0011] Then, the exhaust gas flowing out from the downstream end of the inner pipe into the outer pipe gathers with the exhaust gas flowing down in the outer pipe and flows down to the downstream catalytic converter and the silencer. . According to the exhaust device of the fourth aspect,
The distance from the cylinder head to the junction of the exhaust gas discharged from the No. 1 and No. 4 exhaust ports in the outer cylinder,
Since the distance from the cylinder head to the junction of the exhaust gas discharged from the second and third exhaust ports in the inner cylinder is substantially equal, exhaust interference is prevented.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIGS. 1 to 3 show an exhaust device according to one embodiment of claims 1, 2 and 4.
As in the conventional example shown in FIG.
5 also has an exhaust manifold 17 mounted on a cylinder head of an in-line four-cylinder engine, and the exhaust manifold 17
And a front tube 19 connected to the front tube 19.

As shown in the figure, the exhaust manifold 17 comprises an outer cylinder 25 formed by pressing a pair of upper and lower half-cylinder outer cylinders 21 and 23 formed by press-forming a metal plate, and an outer cylinder 25. The outer cylinder 25 includes four branch pipes 27, 29, 31, and 33 each having a circular cross section communicating with each exhaust port of the engine. It has a left-right symmetric structure integrally formed with the cylinder main body 35.

The branch pipes 27, 29, 31, 33
Flange 37 is welded upstream of the outer cylinder body 3
5 on the downstream side of the connection flange 3 of the front tube 19
9 are welded. On the other hand, the inner cylinder 26 is formed by a pair of upper and lower symmetrical substantially Y-shaped half-broken inner cylinders 41 and 43 formed by press-molding a metal plate. Then, as shown in FIG. 2, one of the exhaust gas introduction ports of the forked pipes 45 and 47 formed at the upstream portion of the inner cylinder 26 has an entire circumference on the inner circumference of the branch pipe 29 communicating with the second exhaust port of the cylinder head. The exhaust gas introduction port of the other forked pipe 47 is welded to the entire circumference of the branch pipe 31 communicating with the third exhaust port of the cylinder head, and is discharged from the second and third exhaust ports. Exhausted exhaust gas is distributed to branch pipes 29 and 31.
And downstream from the inner cylinder 26 via the forked pipes 45 and 47, and from the first and fourth exhaust ports to the branch pipe 2
Exhaust gas introduced through the inner cylinder 26 and the outer cylinder main body 35 as shown in FIG.
Flows down through the outer cylinder 25.

The front tube 19 connected to the exhaust manifold 17 via a flange 51 has a double pipe structure including an outer pipe 53 and an inner pipe 55 at the upstream portion. Outer cylinder 25 of manifold 17
And the inner pipe 55 is connected to the exhaust manifold 17.
And the downstream end 5 of the inner pipe 55.
The exhaust gas flowing out of the outer pipe 53 from the outer pipe 53 gathers with the exhaust gas flowing down in the outer pipe 53. The length from the cylinder head of the engine to the downstream end 55a of the inner tube 55 is 700 to 800 mm.

Since the exhaust device 15 according to the present embodiment is configured as described above, the exhaust gas sequentially discharged from the first and fourth exhaust ports with the driving of the engine is supplied to the branch pipes 27 and 33, respectively. Flows into the outer cylinder 25 from FIG.
As shown in FIG. 5, the outer tube 25 and the outer tube 53 of the front tube 19 flow down while being merged in the gap 49 formed between the inner tube 26 and the outer tube 53 and are sequentially discharged from the second and third exhaust ports. Exhaust gas is discharged from the forked pipes 45 and 47 to the inner cylinder 26, respectively.
The inner tube 55 of the front tube 19 flows down while merging inside. Then, the exhaust gas flowing out from the downstream end 55a of the inner pipe 55 into the outer pipe 53 gathers with the exhaust gas flowing down in the outer pipe 53 and flows down to the downstream catalytic converter and the silencer. It will be.

As is well known, the ignition sequence of a four-cylinder engine is as follows: first cylinder → third cylinder → fourth cylinder → second cylinder or first cylinder → second cylinder → fourth cylinder → third cylinder In this embodiment, the outer cylinder 25 and the inner cylinder 26 formed symmetrically to each other form a double-pipe structure to constitute the exhaust manifold 17, so that the conventional exhaust manifold Thus, the outer cylinder of the exhaust gas discharged from the first and fourth exhaust ports without arranging these branch pipes by performing three-dimensional complicated processing so that the plurality of branch pipes become as long as possible. The distance from the cylinder head to the junction in the cylinder 25 and the distance from the cylinder head to the junction in the inner cylinder 26 of the exhaust gas discharged from the second and third exhaust ports are as follows: Approximately equal length And the downstream end 55a of the inner pipe 55 from the cylinder head of the engine.
By setting the length to 700 to 800 mm, there is no exhaust interference, and it is preferable for measures against back pressure.

As described above, the exhaust device 15 according to this embodiment is
4 and 5, it is possible to prevent exhaust interference and prevent a decrease in engine output, as in the conventional exhaust device 11 shown in FIGS. Length up to 55a is 700-800
mm, it is preferable in terms of countermeasures against back pressure.However, in the present embodiment, a plurality of pipes are three-dimensionally bent to form an exhaust manifold as in the conventional example, or a front tube is formed. Since an operation of welding a partition made of a single plate material to the upstream portion is not required, it is possible to provide a simple exhaust device having a structure that is easier to manufacture and lower in cost than the conventional example.

In the above-described embodiment, the inner cylinder 26 of the exhaust manifold 17 is formed by fitting the pair of half-split inner cylinders 41 and 43 in the middle, but not shown in claims 1, 3 and 4 not shown. As in one embodiment of the invention according to the above, the inner cylinder may be formed symmetrically with a metal pipe and disposed in the outer cylinder 25 as in the above embodiment. Thus, according to such an embodiment, it is possible to achieve the intended purpose, similarly to the above-described embodiment.

[0020]

As described above, the series 4 according to each claim is described.
According to the exhaust device for a cylinder engine, it has become possible to provide a simple exhaust device having a structure that is easier to manufacture and has a lower cost than before. According to the exhaust device of the fourth aspect, it is possible to prevent exhaust interference and prevent a decrease in engine output.

[Brief description of the drawings]

FIG. 1 is a cutaway plan view of a main part of an exhaust device for an in-line four-cylinder engine according to one embodiment of claims 1, 2 and 4. FIG.

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

FIG. 3 is a sectional view taken along line III-III of FIG. 1;

FIG. 4 is an overall perspective view of a conventional exhaust device of an in-line four-cylinder engine.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 15 Exhaust device 17 Exhaust manifold 19 Front tube 21, 23 Half-shell outer cylinder 25 Outer cylinder 26 Inner cylinder 27, 29, 31, 33 Branch pipe 35 Outer cylinder main body 37 Head flange 41, 43 Half-shell inner cylinder 45, 47 Forked pipe 53 outer pipe 55 inner pipe

Claims (4)

[Claims] 1. A four-cylinder engine mounted on a cylinder head of an in-line four-cylinder engine and connected to each exhaust port of the engine.
Exhaust manifold (17) having two branch pipes (27, 29, 31, 33), and the exhaust manifold (17)
An exhaust device (15) for an in-line four-cylinder engine, comprising: a front tube (19) connected to the exhaust tube (19); ), And has four branch pipes (27, 29, 31, 33) connected to respective exhaust ports of the engine.
5) and an exhaust gas inlet is welded to the inner circumference of the branch pipe (29, 31) of the outer cylinder (25) which is disposed in the outer cylinder (25) and connected to the second and third exhaust ports. The exhaust gas discharged from the first and fourth exhaust ports flows down in the outer cylinder (25), and the exhaust gas discharged from the second and third exhaust ports is formed. The inner tube (26) has a double tube structure flowing down, and the upstream portion of the front tube (19) is an outer tube (53).
The outer tube (25) is connected to the outer tube (53), and the inner tube (26) is connected to the inner tube (55) of the front tube (19).
An exhaust device for an in-line four-cylinder engine, characterized in that: 2. An exhaust system for an in-line four-cylinder engine according to claim 1, wherein said inner cylinder comprises a pair of half-cylinder inner cylinders formed by press forming a metal plate. 3. The exhaust system for an in-line four-cylinder engine according to claim 1, wherein the inner cylinder is made of a metal pipe. 4. The distance from the cylinder head to the junction of the exhaust gas discharged from the first and fourth exhaust ports to the junction in the outer cylinder (25) and the exhaust gas discharged from the second and third exhaust ports. 4. The apparatus according to claim 1, wherein the distance from the cylinder head to the confluence of the exhaust gas in the inner cylinder (26) is substantially equal to each other. An exhaust device for an in-line four-cylinder engine according to the description.