JPH1130121A - Exhaust manifold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust manifold capable of restraining generation of high-frequency sound to be generated caused by high-frequency vibration. SOLUTION: An SUS-made exhaust manifold 1 is provided with respective pipe parts 2a, 2b, 2c, 2d for each cylinder, into which exhaust gas of respective cylinders in a four-cycle engine is to be introduced, and a collective part 3 for collecting respective pipe parts 2a, 2b, 2c, 2d into one. A contact part 9 in which respective pipes 2a to 2d are to be brought in contact with one another is formed on this side (the upstream) of the collective part 3 across the length L, flat parts 10 are formed on the contact part 9, and flat parts in respective pipe parts 2a, 2b, 2c, 2d are brought in contact with one another. Respective pipe parts 2a to 2d are fastened by constricting bands 12, 13 in a state where the flat parts in the pipe parts 2a, 2b, 2c, 2d are brought in contact with one another.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust manifold which is a component of an exhaust system of a multi-cylinder engine.

[0002]

2. Description of the Related Art Recently, an exhaust manifold of a stainless steel (SUS) pipe type has been used. In the case of SUS exhaust manifolds, when the cast iron exhaust manifold was mainly used, the material of the exhaust manifold was changed to SUS (stainless steel) due to requirements for exhaust gas regulations, high heat resistance, light weight, etc. As a result, a SUS exhaust manifold composed of SUS pipes has been used.

FIG. 6 shows an example of the configuration of this SUS exhaust manifold. The SUS exhaust manifold 30 has four pipe sections 3 corresponding to four engine cylinders.
1 and an assembly portion 32 in which all the pipe portions 31 are assembled, and are directly bolted to a cylinder head of a four-cylinder engine by a flange 33. Also, this SUS
The exhaust manifold 30 is fixed by a flange 34 to a front pipe 35 and bolts / nuts 36 and 37 and connected to the muffler side.

[0004] With this structure, the exhaust gas discharged from each cylinder of the four-cylinder engine passes from the exhaust port through the pipe portion 31 of the SUS exhaust manifold, gathers at the collecting portion 32, and then collects the front pipe 3.
5. Discharged to muffler.

[0005]

However, this SUS
Since the exhaust manifold 30 is made of a SUS pipe having a shape shown in FIG. 6 and having a thickness of about 2 mm, compared with a cast iron exhaust manifold, the high frequency vibration damping is slow and the high frequency vibration is easily generated. Therefore, there is a problem that the vibration generated in the bent portion P10 and the gathering portion 32 is transmitted to the entire manifold, and the same level of high-frequency sound (radiated sound) is simultaneously generated from the entire manifold.

An object of the present invention is to provide an exhaust manifold capable of suppressing generation of high-frequency sound due to high-frequency vibration.

[0007]

According to a first aspect of the present invention, there is provided an exhaust manifold wherein a flat portion is formed in each pipe portion of each cylinder, and the flat portions in each pipe portion are brought into contact with each other.

With such a configuration, the pulsation of the exhaust gas discharged from each cylinder of the multi-cylinder engine hits a bent portion or a collective portion of the pipe portion of the exhaust manifold, generating vibration, and the vibration is transmitted to the flat portion. I do. At this time, since the pipe portions are in contact with each other at the flat portion, the above-described vibration is attenuated, and high-frequency vibration transmitted to the entire manifold is suppressed. As a result, high-frequency sound (radiated sound) generated from the entire manifold can be reduced.

In this case, when each pipe portion is tightened with a restraining band in a state where the flat portions in each pipe portion of each cylinder are in contact with each other, the vibration damping effect by the contact is maximized. Drawn to.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an exhaust manifold 1 made of SUS in this embodiment. This SUS exhaust manifold 1 is mounted on a four-cylinder engine. The exhaust manifold 1 has the same basic structure as the SUS exhaust manifold 30 shown in FIG. 6, but has pipe sections 2a, 2b, 2 for each cylinder.
There is a characteristic in a portion where c and 2d gather.

The details will be described below. The SUS exhaust manifold 1 has four SUS pipe sections 2a, 2b, 2c, and 2 corresponding to four cylinders of the engine, similarly to the SUS exhaust manifold 30 shown in FIG.
d, and a SUS collecting section 3 in which all the SUS pipe sections 2a, 2b, 2c, 2d are gathered into one. The pipe sections 2a, 2b, 2c, 2d are cylinders in the four-cylinder engine ({1, {from the left in FIG. 1}, respectively).
2, # 3, # 4 cylinder) exhaust gas is introduced. A flange 4 is provided at an end of each of the four pipes 2a, 2b, 2c, 2d, so that the flange 4 can be directly bolted to a cylinder head of the engine. Further, a flange 5 is provided at an end of the collecting part 3, and the flange 5 allows the front pipe 6 and the bolt
The SUS exhaust manifold 1 is fixed by nuts 7 and 8 and connected to the muffler side.

When the four-cylinder engine is driven, exhaust gas is exhausted from each cylinder through an exhaust port, and the exhaust gas is introduced into the pipe portions 2a, 2b, 2c, 2d of the SUS exhaust manifold, and the pipe portions 2a, 2d
The exhaust gas passes through b, 2c, and 2d and gathers at the gathering section 3,
Then, it is discharged to the front pipe 6 and the muffler.

In the exhaust manifold 1 made of SUS, a contact portion 9 with which the pipe portions 2a to 2d come into contact is formed over the length L in front (upstream side) of the collecting portion 3. That is, the upstream part of the collecting part 3 is formed to be long as the contact part 9. In this contact part 9, 4
The pipe portions 2a, 2b, 2c, 2d are bundled and come into contact with each other.

A cross section of the contact portion 9, that is, AA in FIG.
The cross section is shown in FIG. Pipe portions 2a, 2b, 2 of each cylinder
In c and 2d, flat portions 10 are provided on adjacent pipe portions. That is, two flat portions 10 are formed in each of the pipe portions 2a, 2b, 2c, 2d.
The flat portion 10 is formed over the entire area (length L) of the contact portion 9 in FIG. 1, and the pipe portions are in surface contact with each other at the flat portion 10. In FIG. 2, an arc portion 11 is formed between the flat portions 10 in one pipe portion 2a, 2b, 2c, 2d.

The pipe sections 2a, 2b, 2c, 2d
Has a circular cross section from immediately after the exhaust port of the four-cylinder engine to just before the contact portion 9. In addition, as shown in FIG.
In a state in which a, 2b, 2c, and 2d are bundled, binding bands 12, 13 are provided at two locations on the outer peripheral surface.
The four pipe parts 2a,
2b, 2c, and 2d are tightened to positively promote the contact between the flat portions 10 described above. That is, restraint band 1
The contact portions 9 are provided at two places in the contact portion 9 to assist the contact between the pipe portions.

FIG. 3 shows a cross section of the contact portion 9 at a position where the restraining bands 12, 13 are installed, that is, a cross section taken along line BB of FIG. The restraining bands 12, 13 are semicircular strips 14, 15,
It consists of. The strip plates 14 and 15 are manufactured by bending a single plate material into a semicircular shape. At the time of mounting, the two band plates 14, 15 are arranged to be pressed from the outer peripheral side of the bundled pipe portions 2a, 2b, 2c, 2d, and the end portions of the band plates 14, 15 are brought into contact with each other. The tips of the strips 14 and 15 are welded. In FIG. 3, welds are indicated by 16a and 16b. In this manner, the four pipe sections 2a, 2b, 2c, 2
d is tightened.

Next, the operation of the exhaust manifold 1 configured as described above will be described. As described above, the exhaust gas discharged from each cylinder of the four-cylinder engine is S
US exhaust manifold pipes 2a, 2
Exhaust gas passes through b, 2c, and 2d, passes through the contact portion 9, reaches the collecting portion 3, and is collected, and then is discharged to the front pipe 6 and the muffler.

As described above, the exhaust gas passes through the exhaust manifold 1, and the exhaust gas passes through the pipe section 2.
A high frequency vibration is generated by the exhaust pulsation at the bent portions (portions indicated by P1 in FIG. 1) and the collecting portion 3 at the portions a, 2b, 2c, and 2d. That is, the bent portion P
1 and the gathering unit 3 are the excitation sources. The vibration thus generated is transmitted to the flat portion 10. At this time, the high-frequency vibration is attenuated by friction caused by contact between the pipes, and the high-frequency vibration transmitted to the entire manifold is reduced. As a result, high-frequency sound generated from the entire manifold is reduced.

As described above, the SUS exhaust manifold 1 of the present embodiment has a curved portion P1 and a gathering portion 3 which are vibration sources.
, The transmission system of the high-frequency vibration, that is, the high-frequency sound (6 kHz to
By devising a transmission system of 20 kHz), the vibration generated by the vibration source is suppressed from being transmitted to the entire SUS exhaust manifold. Therefore, the pipe portions 2a and 2a are connected to the SUS exhaust manifold 30 shown in FIG.
Since the generation of high-frequency sound can be reduced by changing the method of assembling b, 2c, and 2d, a high-frequency sound reduction effect can be obtained at low cost and with minimum additional weight. In other words, if the thickness of the exhaust manifold is increased to reduce the high-frequency noise level, the overall weight of the manifold will increase.
And low cost.

In an engine designed to improve the engine output, it is considered that it is desirable to make the pipe portion of each cylinder of the exhaust manifold longer and equal in length. Therefore, in the exhaust manifold 1 of FIG. 1, since the pipe portions 2a, 2b, 2c, 2d are long and equal in length, the exhaust manifold 1 has a structure having both an output improving effect and a high frequency sound reducing effect.

As described above, this embodiment has the following features. (A) A flat portion 10 is formed in each of the pipe portions 2a, 2b, 2c, 2d for each cylinder, and each of the pipe portions 2a, 2b, 2c, 2d.
In the exhaust manifold 1 made of SUS, the exhaust gas impinges on the bent portion P1 and the gathering portion 3 in FIG. 1 to generate vibration due to exhaust pulsation. , 2
Since c and 2d are in contact with each other, high-frequency vibration is attenuated at the contact portion 9, and high-frequency vibration transmitted to the entire manifold is suppressed. As a result, high-frequency sound (radiated sound) generated from the entire manifold can be reduced. (B) Each of the pipe sections 2 in a state where the flat sections 10 of the pipe sections 2a, 2b, 2c and 2d of each cylinder are in contact with each other
Since a, 2b, 2c and 2d are fastened by the restraint bands 12 and 13, the vibration damping effect by contact can be maximized. (Second Embodiment) Next, a second embodiment will be described with reference to the first embodiment.
The following description focuses on the differences from this embodiment.

FIG. 4 shows an exhaust manifold according to this embodiment. 4 corresponds to FIG. 2 and corresponds to a cross section of the contact portion 9 in FIG. 1, that is, a cross section taken along the line AA in FIG.

In the contact portion 9 of the exhaust manifold, a flat portion 17 extending at a right angle is used in this embodiment as a shape of the flat portion where the pipe portions contact each other. The four pipe portions 2a, 2b, 2c, 2d are in contact with the flat portion 17 without any gap. That is, in FIG. 2, the circular arc portion 11 is formed between the flat portions 10 of the one pipe portion 2a, 2b, 2c, 2d, and the four pipe portions 2a, 2b, 2c,
In the state where 2d is bundled, a space 18 is formed at the center thereof, but in the present example of FIG. 4, the space is formed at the center of the four pipes 2a, 2b, 2c and 2d while being bundled. Four pipe sections 2a, 2b, 2 without being formed
c and 2d are in contact with no gap.

As described above, in this embodiment, the area of the flat portion 17 is increased, and the contact area between the pipes is further increased. Thereby, high frequency vibration can be further attenuated by contact friction.

The other structure is the same as that of FIG. (Third Embodiment) Next, a third embodiment will be described with reference to the first embodiment.
The following description focuses on the differences from this embodiment.

FIG. 5 shows an exhaust manifold according to this embodiment. FIG. 5 corresponds to FIG. 3 and shows a contact portion 9 at a position where the restraining bands 12 and 13 of FIG.
, That is, the cross section taken along the line BB in FIG.

As the restraining bands 12 and 13, strips 19 and 20 shaped so as to be in contact with the outer peripheral surfaces of the pipes 2a, 2b, 2c and 2d for the entire cylinder are used.
9 and 20 have fastening plate portions 21a and 21b at their ends. Then, the fastening plate portions 21a, 21b
Are fastened and fixed by bolts and nuts 22 and 23.

The restraining bands 12, 13 thus configured
By using, the high frequency vibration can be further attenuated by tightening the flat portions 10 of the pipe portions 2a to 2d in a state where the flat portions 10 are in contact with each other more reliably.

In the above description, an exhaust manifold mounted on a four-cylinder engine has been described. However, the present invention may be embodied as an exhaust manifold suitable for a two-cylinder engine, a three-cylinder engine, or an engine having five or more cylinders. . That is, the number of pipes may be two, three, five or more, in addition to four.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an exhaust manifold according to a first embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

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

FIG. 4 is a cross-sectional view of an exhaust manifold according to a second embodiment.

FIG. 5 is a cross-sectional view of an exhaust manifold according to a third embodiment.

FIG. 6 is a configuration diagram of a conventional exhaust manifold.

[Explanation of symbols]

1. Exhaust manifold, 2a, 2b, 2c, 2
d: pipe portion, 3: collecting portion, 10: flat portion, 12, 13
… Restricted band

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kenichi Yamamoto 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (2)

[Claims] 1. An exhaust manifold comprising: a pipe section for each cylinder into which exhaust gas of each cylinder is introduced in a multi-cylinder engine; and an collecting section for collecting the pipe sections into one. An exhaust manifold, wherein a flat portion is formed in a pipe portion, and the flat portions in each pipe portion are brought into contact with each other. 2. The exhaust manifold according to claim 1, wherein each pipe portion is tightened with a restraining band in a state where the flat portions of each pipe portion are in contact with each other.