JPH1089062A - Exhaust manifold for a multi-cylinder internal combustion engine - Google Patents

Abstract

(57) [Summary] (Problem corrected) [PROBLEMS] To provide a sheet metal exhaust manifold that is rich in heat insulation, lightweight, and high in vibration resistance in an in-line multi-cylinder internal combustion engine mounted on an automobile or the like. An exhaust manifold (1) comprises a steel upstream flange (2), a downstream flange (3), a stainless steel exhaust manifold pipe (4) made of sheet metal, a stainless steel exhaust manifold chamber (5) made of sheet metal, and those pipes and chambers. And an exhaust manifold 6 made of sheet metal. The upstream flange is provided with four holes 10 connected to the exhaust port of the cylinder head, and a bolt hole 11 for inserting a bolt screwed into the head. The exhaust manifold chamber is formed by aligning two press-molded front and rear chamber halves 18 and 18 in the middle, and integrally joining the upstream end contact portions 20 to each other by welding. The downstream end 17 of the exhaust manifold pipe is fitted to the branch upstream opening end so as to be relatively movable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust manifold having high exhaust gas heat retention in a multi-cylinder internal combustion engine mounted on an automobile or the like.

[0002]

2. Description of the Related Art Cast exhaust manifolds have a large wall thickness and a large weight, which hinders the weight reduction of an internal combustion engine and, consequently, a vehicle body on which the exhaust manifold is mounted. Thus, there is a problem that the initial function of the exhaust gas purifying catalyst is reduced.

In order to solve such a problem, there is an exhaust manifold disclosed in Japanese Utility Model Publication No. 4-1292.

In the exhaust manifold described in that publication, the upstream end of a cylindrical guide pipe is attached to each mounting hole of a flange attached to the opening end of the exhaust port, and the outer periphery of the plurality of cylindrical guide pipes is set. The downstream end of the covering manifold case is mounted in the hole of the exhaust pipe mounting flange.

[0005]

In the exhaust manifold described in the above publication, the upstream end of the cylindrical guide pipe is fitted and fixed in a mounting hole of a flange, but the downstream end of the cylindrical guide pipe is connected to a manifold case. Because it is merely arranged with a space to it, it can freely move not only in the longitudinal direction of the cylindrical guide pipe but also in the direction perpendicular to the longitudinal direction of the cylindrical guide pipe in the manifold case. The cylindrical guide pipe vibrates due to vibration, periodic exhaust pressure fluctuations in the manifold case, and the like, and the cylindrical guide pipe comes into contact with the manifold case by external force such as gravity or acceleration force,
Vibration and noise generated in the cylindrical guide pipe are radiated into the atmosphere through the manifold case, so that there is a problem in that vibration and noise insulation are reduced. In addition, the cylindrical guide pipe comes into contact with the manifold case, heat in the exhaust gas is radiated from the cylindrical guide pipe to the atmosphere via the manifold case, and the exhaust gas temperature is lowered.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an improvement in an exhaust manifold of a multi-cylinder internal combustion engine which overcomes the above-mentioned drawbacks, and an upstream end of a thin branch pipe of an exhaust manifold is provided at an exhaust port of each cylinder of the internal combustion engine. In a multi-cylinder internal combustion engine exhaust manifold in which the downstream portions of the branch pipes are gathered and connected to a sheet metal gathering portion, a sheet metal case is mounted with a space around the branch pipe and the gathering portion, and the branching is performed. An upstream end of the pipe and the case is welded to an upstream flange, a downstream end of the collecting portion and the case is welded to a downstream flange, and the branch pipe and the collecting portion are branched by a slide portion. The slide portion is held so as to be relatively movable along the longitudinal direction, and the slide portion is pressed and held by the outside by the collecting portion and the case. It is characterized by that.

According to the present invention, as described above, the exhaust gas flowing out of the exhaust port from each cylinder of the internal combustion engine passes through the branch pipe and then flows into the collecting section. Since the exhaust gas merges with the exhaust gas that has passed through the other branch pipes and is discharged to the exhaust pipe, the exhaust gas can flow smoothly without disturbing the flow, and the engine output and efficiency are maintained at a high level.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention shown in FIGS. 1 to 6 will be described below. The exhaust manifold 1 is an exhaust manifold used for an in-line four-cylinder, four-stroke internal combustion engine mounted on a passenger car (not shown). The exhaust manifold 1 includes a steel upstream flange 2, a steel downstream flange 3, and a steel downstream flange 4. A stainless steel exhaust manifold 4 serving as a branch pipe, a stainless steel exhaust manifold chamber 5 serving as a sheet metal collecting portion, and a stainless exhaust manifold case 6 serving as a case covering the exhaust manifold 4 and the exhaust manifold 5;
As shown in FIG. 1, the upstream flange 2 includes:
Four holes 10 each connected to a downstream opening of an exhaust port of a cylinder head (not shown) of the internal combustion engine, and bolt holes for passing bolts screwed to the cylinder head.
The downstream flange 3 has a hole 12 connected to an exhaust pipe (not shown), a screw hole 14 into which a male screw 13 that passes through a flange at the upstream end of the exhaust pipe is screwed, and a cylinder (not shown). A bolt hole 15 for connecting to the block via a bracket is formed.

In the exhaust manifold chamber 5, two press-molded front and rear chamber halves 18 and 19 are aligned in the middle, and their upstream ends 20 are joined together by welding. The downstream end 17 of the exhaust manifold 4 is relatively slidably fitted into each of the branch upstream opening ends 21 of the exhaust manifold 5.

Further, the exhaust manifold case 6 also includes two press-molded front and rear case halves 24 and 25 joined together in the middle, and as shown in a thick line in FIG. The entire outer peripheral portion is integrally joined by welding, and its branch upstream end 26 is connected to the exhaust pipe 4
Communication hole of the upstream flange 2 close to the outer periphery of the upstream end 16
10, and as shown by the bold lines in FIGS. 4 and 5,
The holes 10 of the upstream flange 2, the upstream end 16 of the exhaust manifold 4, and the branch upstream end 26 of the exhaust manifold 6 are welded together.
And the collecting downstream end 27 is closely fitted to the outer peripheral surface of the collecting downstream opening end 22 of the exhaust manifold 5 and is fitted into the hole 12 of the downstream flange 3. The communication hole 12 of the flange 3, the collecting downstream opening end 22 of the exhaust manifold 5, and the collecting downstream end of the exhaust manifold 6.
27 are integrally connected to each other, and outside the fitting portion between the exhaust manifold pipe 4 and the exhaust manifold chamber 5, the outer case half 24 and the rear case half 25 of the exhaust manifold 6 are curved inward. It is pushed by the inward bending portion 28 and the inward bending portion 29.

Further, the front side of the exhaust manifold 5
The chamber half 18 is located downstream of the
When the attachment hole 23 is formed, the front side of the exhaust manifold case 6
Attach the sensor to the case half 24 at the corresponding position
Drilled holes 30 are formed, and these sensor mounting holes 23 and 30 are formed.
Not shown in the exhaust manifold 5 through _Two
The detection part of the sensor is configured to protrude.

In addition, the internal combustion engine 1, 2,
1, 2, which are respectively connected to the exhaust ports of the third and fourth cylinders
Holes 1,2,3,4 in holes 3 ₁ , 10 ₂ , 10 ₃ , 10 ₄
Although exhaust manifold pipe 4 ₁ turn, 4 _2, 4 _3, 4 ₄ are connected, as is clear from FIG. 1, the hole 10 ₁ of the No. 1, 4, 10
_4, the result is located away against hole 12 of the downstream flange 3, 1,4 No. exhaust manifold pipe 4 _1, 4 ₄ of the downstream end 17 _1, 17 ₄ is a front view of FIG. 1 , as compared to the exhaust manifold pipe 4 _2, 4 ₃ of the downstream end 17 _2, 17 ₃ of 2, the third, and is opened in the exhaust manifold chamber 5 at a position away from the hole 12 of the downstream flange 3.

A heat-absorbing sound-absorbing material 32 such as glass wool is applied to the outer peripheral surface of the exhaust manifold case 6 and its outer surface is covered with exhaust manifold covers 33 and 34, and both are integrally connected by bolts and nuts 35. ing.

Since the embodiments shown in FIGS. 1 to 6 are configured as described above, when the internal combustion engine (not shown) starts operating, the high-temperature exhaust gas generated in the combustion chamber of each cylinder is exhausted (not shown). Upstream flange 2 from port
Communication hole 10, exhaust manifold 4, exhaust manifold 5
The exhaust gas is discharged to an exhaust pipe (not shown) through the communication hole 12 of the downstream flange 3.

When the internal combustion engine is started, the exhaust manifold 1 is in a low temperature state and tends to absorb the heat of the exhaust gas to cool the exhaust gas.
The exhaust manifold 5 and the exhaust manifold 6 are both made of thin sheet metal, have a small heat capacity, and have a double structure in which the exhaust manifold 6 has a space with respect to the exhaust manifold 4 and the exhaust manifold 5, so that the exhaust manifold is rich in heat insulation. Therefore, the exhaust gas is not cooled down to a low temperature, the exhaust gas purifying catalyst in the exhaust pipe (not shown) can be immediately activated, and the initial function of the exhaust gas purifying catalyst at the time of start-up is reduced. can avoid.

The exhaust passage in the exhaust manifold 6 of the exhaust manifold 1 is composed of an exhaust manifold 4 and an exhaust manifold 5 divided in two along the direction of the exhaust passage, and a downstream end 17 of the exhaust manifold 4 is connected to the exhaust manifold 5. Of the exhaust manifold 4 and the exhaust manifold 5
However, as a result of being heated to a higher temperature than the exhaust manifold 6,
Even if the amount of thermal expansion of the exhaust manifold 4 and the exhaust chamber 5 is larger than the amount of thermal expansion of the exhaust manifold 6, the difference in thermal expansion is absorbed by the relative sliding between the exhaust manifold 4 and the exhaust manifold 5. A large thermal stress is prevented from being generated in the exhaust manifold 4, exhaust manifold chamber 5, and exhaust manifold case 6.

Further, even if the downstream end 17 of the exhaust manifold 4 is slidably fitted into the upstream opening end 21 of the exhaust manifold 5, the front case half 24 of the exhaust manifold 6 and Since it is pressed inward by the outwardly curved portion 28 and the inwardly curved portion 29 of the rear case half 25, even if vibration generated in the internal combustion engine (not shown) is transmitted to the exhaust manifold 1, Downstream end 17
The vibration of the fitting portion between the pump and the upstream end 21 of the exhaust manifold 5 is reliably suppressed.

Further, in the four cylinders of the internal combustion engine (not shown), combustion occurs at equal intervals in the order of the first, third, fourth, and second cylinders, and the _first and fourth exhaust manifolds 4 ₁ , 4 _Four
The open ends 17 ₁ , 17 ₄ and 2, the third exhaust manifold pipe 4 ₂ ,
4 for _{the third} and the open end 17 _2, 17 ₃ are arranged by shifting the position, without causing exhaust interference is dynamic effect is sufficiently exhibited exhaust, intake efficiency is indirectly increased , Engine power and efficiency can be improved.

Further, the downstream end 17 of the exhaust manifold 4 is slidably fitted into the upstream open end 21 of the exhaust manifold 5, and even if this fitting portion is not airtight, the outer periphery of the exhaust manifold 4 and the outer periphery of the exhaust manifold 5 are provided. Since the surface is hermetically sealed by the exhaust manifold 6, leakage of exhaust gas can be prevented beforehand.

Each downstream end 17 of the exhaust manifold 4 is
The exhaust manifold protrudes to the vicinity of the center in the exhaust manifold chamber 5 whose space is reduced toward the downstream, and is opened toward the downstream end of the collection, so that the exhaust gas is rectified and the exhaust manifold is smoothly operated without causing large turbulence. Exhaust gas can flow through the inside 1 and the suction efficiency can be improved by lowering the exhaust resistance.

Further, an air heat insulating layer is formed between the exhaust manifold 4 and the exhaust manifold 5 and the exhaust manifold 6, and a fitting portion between the exhaust manifold 4 and the exhaust manifold 5 that generates a higher temperature and generates a loud noise. Since the outside of the exhaust manifold 1 is covered with the sound absorbing material 32 and the exhaust manifold covers 33 and 34, the heat insulation and heat insulation of the exhaust manifold 1 are ensured, and the sound absorbing effect is high.

Further, an exhaust manifold 4 and an exhaust manifold 5 forming an exhaust gas passage are provided with an upstream end 16,
Except for the collecting downstream opening end 22 and the curved portions 28 and 29, the exhaust manifold 4 is completely separated from the exhaust manifold 6, and an air heat insulating layer is formed between the exhaust manifold 4 and the exhaust manifold 5 and the exhaust manifold 6. The heat transfer from the exhaust manifold 4 and the exhaust manifold 5 to the exhaust manifold 6 is suppressed, a decrease in exhaust gas temperature immediately after the start of the internal combustion engine is avoided, and radiant heat from the exhaust manifold 6 to the outside is suppressed. The temperature is kept low.

Moreover, each exhaust manifold pipe 4, _1, 4, _2, 4, _3, 4 ₄
Can be freely slid with respect to the exhaust manifold 5, so that thermal stress generation due to thermal shrinkage is suppressed and stress generation due to vibration is also prevented, so that the durability of the exhaust manifold 4 and the exhaust manifold 5 is improved.

Further, since the sound absorbing material 32 and the exhaust manifold covers 33 and 34 are covered on the outer periphery of the exhaust manifold chamber 5 where the exhaust gas from each cylinder gathers at the highest temperature and generates a loud noise,
The noise level in the engine room is greatly reduced.

As shown in FIGS. 7 and 8, the branch upstream portion 37 of the exhaust manifold 5 in the exhaust manifold 36 is protruded outward, and the branch upstream portion 37 and the downstream end 17 of the exhaust manifold 4 are connected to each other. In addition to the steel mesh 38 interposed between the upstream manifold 37 and the exhaust manifold 6, the steel mesh 39 may be interposed between the branch upstream portion 37 and the exhaust manifold 6. The sliding of the fitting portion of the pipe 4 and the exhaust manifold 5 can be performed more smoothly.

When attaching the meshes 38 and 39,
Perform spot welding, or place mesh 3 on exhaust manifold 6, exhaust manifold 4, or exhaust manifold 5.
Forming recesses that can accommodate 8, 39, meshes 38, 39
Can be securely fixed to prevent falling off.

Further, as shown in FIGS. 9 and 10, a reinforcing short pipe 40 may be integrally fitted to the outer periphery of the branch upstream opening end 21 of the exhaust manifold 5 and welded. The strength of the branch upstream open end 21 can be increased, and its durability can be improved.

[0028]

As described above, according to the present invention, since the branch pipe and the gathering portion are held by the slide portion so as to be relatively movable along the longitudinal direction of the branch pipe, the branch pipe is directly contacted with the high-temperature exhaust gas and is connected to the branch pipe. Even if the collecting portion is heated to a high temperature, and these branch pipes and the collecting portion expand and contract significantly along the flow direction of the exhaust gas, the expansion and contraction is caused by the relative movement of the branch pipe and the collecting portion by the slide portion. The absorption is suppressed, and the generation of thermal stress in the branch pipe, the collecting portion and the case is suppressed, and the durability of the exhaust manifold is improved.

In the present invention, since the branch pipe is thin and the collecting portion is made of sheet metal, the heat capacity of both is small, and the branch pipe and the collecting portion are covered with the case with a space. Therefore, even when the internal combustion engine is started immediately, the branch pipe and the collecting portion are rapidly heated to a high temperature, so that the exhaust gas is maintained at a high temperature, and the exhaust gas purification catalyst Is immediately activated, and the exhaust gas can be sufficiently purified even immediately after starting. In addition, since the exhaust manifold has excellent heat insulating properties, radiant heat radiated from the exhaust manifold is reduced, and the ambient temperature in the engine room is kept low.

Further, in the present invention, the branch pipe and the gathering portion are movably held along the longitudinal direction of the branch pipe by a slide portion, and the slide portion is pressed from the outside by the gathering portion and the case. Even if the exhaust manifold receives the vibration generated in the internal combustion engine or the vibration of the vehicle equipped with the internal combustion engine, the slide portion is stably held in a stationary state, The generation of stress in the slide portion is suppressed, and the durability of the slide portion and the branch pipe is improved.

Further, according to the present invention, since the slide portion is directly held by the inwardly protruding portions formed on the collecting portion and the case, the support rigidity is improved with a simple configuration. In addition, heat conduction from the branch pipe and the collecting portion heated to a high temperature in contact with the exhaust gas to the case is suppressed, and the exhaust gas is maintained at a sufficiently high temperature.

Further, according to the present invention, the slide portion is held by the meshes disposed between the branch pipe and the collecting portion and between the collecting portion and the case. In addition, the heat insulating property is maintained at a high level, and smoother movement against thermal expansion or thermal contraction becomes possible.

[Brief description of the drawings]

FIG. 1 is a front view of an embodiment of an exhaust manifold of a multi-cylinder internal combustion engine according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a side view of FIG. 1;

FIG. 4 is a vertical sectional side view taken along line IV-IV in FIG. 1;

FIG. 5 is a vertical sectional side view taken along line VV of FIG. 1;

FIG. 6 is a vertical cross-sectional side view taken along line VI-VI of FIG. 1;

FIG. 7 is an enlarged vertical sectional side view of a main part of still another embodiment.

FIG. 8 is a cross-sectional view taken along line VIII-VIII of FIG. 7;

FIG. 9 is an enlarged front view of a main part of another embodiment with an exhaust manifold case removed.

FIG. 10 is a vertical sectional side view of a relevant part taken along line XX of FIG. 9;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Exhaust manifold, 2 ... Upstream flange, 3 ... Downstream flange, 4 ... Exhaust pipe, 5 ... Exhaust chamber, 6 ... Exhaust case, 10 ... Hole, 11 ... Bolt hole, 12
... Hole, 13 ... Male thread, 14 ... Screw hole, 15 ... Bolt hole, 16 ... Upstream end, 17 ... Downstream end, 18 ... Front chamber half, 19 ... Back chamber half, 20 ... Upstream end, 21 ... Branch upstream Open end,
22: assembly downstream opening end, 23: sensor mounting hole, 24: front case half, 25: back case half, 26: branch upstream end,
27 ... downstream end of assembly, 28 ... outward curved part, 29 ... inward curved part,
30 ... Sensor mounting hole, 32 ... Sound absorbing material, 33 ... Exhaust manifold cover, 34 ... Exhaust manifold cover, 35 ... Bolt nut, 36 ... Exhaust manifold, 37 ... Upstream branch, 38 ... Mesh, 39 ... Mesh, 40 ... Reinforced short pipe .

Continuing from the front page (72) Inventor Taku Komatsuda 1-4-1 Chuo, Wako-shi, Saitama Pref. Inside Honda Research Institute (72) Inventor Kazuo Ishii 1-4-1 Chuo, Wako-shi, Saitama Co., Ltd. Honda Technical Research Institute

Claims (3)

[Claims] In an exhaust manifold of a multi-cylinder internal combustion engine, an upstream end of a thin-walled branch pipe of an exhaust manifold is connected to an exhaust port of each cylinder of the internal combustion engine, and a downstream portion of the branch pipe is gathered and connected to a sheet metal assembly. A sheet metal case is attached to the outer circumference of the branch pipe and the collecting portion with a space, and an upstream end of the branch pipe and the case is welded to an upstream flange, and a downstream end of the collecting portion and the case. The part is welded to the downstream flange, and the branch pipe and the gathering part are held by the slide part so as to be relatively movable along the longitudinal direction of the branch pipe, and the slide part is separated from the outside by the gathering part and the case. An exhaust manifold for a multi-cylinder internal combustion engine, which is held down and held. 2. The exhaust manifold for a multi-cylinder internal combustion engine according to claim 1, wherein said slide portion is directly held by inwardly protruding portions respectively formed on said collecting portion and said case. 3. The apparatus according to claim 1, wherein the slide portion is held by meshes disposed between the branch pipe and the collecting portion and between the collecting portion and the case. Exhaust manifold for a multi-cylinder internal combustion engine.