JP2020169576A - Exhaust structure of internal combustion engine - Google Patents

Abstract

To suppress the thermal deformation of an exhaust manifold.SOLUTION: An exhaust structure of an internal combustion engine in which at least three pieces of cylinders are arranged in parallel with one another comprises: a cylinder head (11) having a plurality of exhaust ports which are formed in response to the cylinders; an exhaust manifold (2) connected to the plurality of exhaust ports; and a reinforcing member (6) for reinforcing the exhaust manifold. The exhaust manifold has a plurality of exhaust branch pipes (21a to d) extending from the plurality of exhaust ports, an aggregation part (22) for aggregating downstream end sides of the plurality of exhaust branch pipes into one unit, and fixing parts (23) for fixing the reinforcing member. The fixing parts are arranged at upstream end sides of the two exhaust branch pipes which are arranged at both end sides out of the plurality of exhaust branch pipes. The reinforcing member extends in an alignment direction of the cylinders so as to cover the upstream end sides of the plurality of exhaust branch pipes, and end parts of the reinforcing member are fixed to the fixing part.SELECTED DRAWING: Figure 1

Description

The present invention relates to an exhaust structure of an internal combustion engine.

In a multi-cylinder engine used in a vehicle or the like, an exhaust manifold is connected to an exhaust port of a cylinder head. A heat-insulating sound-insulating cover for blocking heat and noise is attached to the exhaust manifold (see, for example, Patent Document 1).

The heat and sound insulation cover described in Patent Document 1 is formed so as to cover the entire exhaust manifold. One end of the heat / sound insulation cover is fixed to the flange on the cylinder head side, and the other end is fixed to the confluence of the cylinders.

JP-A-2002-235554

However, when the entire exhaust manifold is covered with a heat insulating sound insulating cover as in Patent Document 1, although it is possible to prevent the heat of the exhaust manifold from diffusing to the surroundings, the heat is transferred between the exhaust manifold and the heat insulating sound insulating cover. It will be easy to muffle. As a result, there is a problem that the exhaust manifold is thermally deformed and causes plastic strain at the connection portion with the cylinder head.

The present invention has been made in view of the above points, and an object of the present invention is to provide an exhaust structure of an internal combustion engine capable of suppressing thermal deformation of an exhaust manifold.

The exhaust structure of an internal combustion engine according to one aspect of the present invention is an exhaust structure of an internal combustion engine in which at least three cylinders are arranged in parallel, and includes a cylinder head having a plurality of exhaust ports provided corresponding to the cylinders. The exhaust manifold includes an exhaust manifold connected to the plurality of exhaust ports and a reinforcing member for reinforcing the exhaust manifold, and the exhaust manifold includes a plurality of exhaust branch pipes extending from the plurality of exhaust ports and the plurality of exhausts. It has a collecting portion that gathers the downstream end sides of the branch pipes into one, and a fixing portion that fixes the reinforcing member, and the fixing portions are arranged on both end sides of the plurality of exhaust branch pipes. Each of the reinforcing members is provided on the upstream end side of the exhaust branch pipe, and the reinforcing member extends in the arrangement direction of the cylinder so as to cover the upstream end side of the plurality of exhaust branch pipes, and each end is fixed. It is characterized in that it is fixed to a part.

According to the present invention, thermal deformation of the exhaust manifold can be suppressed.

It is a front view of the internal combustion engine which concerns on this embodiment. It is a right side view of the internal combustion engine which concerns on this embodiment. It is a left side view of the internal combustion engine which concerns on this embodiment. It is a top view of the internal combustion engine which concerns on this embodiment. It is a figure which omitted the reinforcing member in the internal combustion engine of FIG. It is a figure which omitted the reinforcing member in the internal combustion engine of FIG. It is a simple substance figure of the reinforcing member which concerns on this embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. For each direction shown in the attached drawings, the front of the vehicle is represented by the arrow FR, the rear of the vehicle is represented by the arrow RE, the upper part of the vehicle is represented by the arrow UP, the lower part of the vehicle is represented by the arrow LO, the left side of the vehicle is represented by the arrow L, and the right side of the vehicle is represented by the arrow R. I will decide. Further, in each of the following figures, some configurations are omitted for convenience of explanation.

The exhaust structure of the internal combustion engine according to the present embodiment will be described with reference to FIGS. 1 to 4. FIG. 1 is a front view of an internal combustion engine according to the present embodiment. FIG. 2 is a right side view of the internal combustion engine according to the present embodiment. FIG. 3 is a left side view of the internal combustion engine according to the present embodiment. FIG. 4 is a top view of the present embodiment. Further, in the present embodiment, the internal combustion engine applied to a vehicle such as a four-wheeled vehicle will be described, but the applicable vehicle is not limited to this and can be appropriately changed. For example, the exhaust structure of the internal combustion engine according to the present embodiment may be applied to another vehicle such as a two-wheeled vehicle.

As shown in FIGS. 1 to 4, the engine 1 as an internal combustion engine is composed of an in-line 4-cylinder engine. In the present embodiment, the alignment direction of each cylinder is directed to the vehicle width direction (left-right direction), and the advancing / retreating direction of the piston (not shown) is directed to the vertical direction.

Specifically, the engine 1 includes a cylinder block 10 that houses the main parts of the engine 1, such as a crankshaft and a piston (both not shown). The crankshaft extends in the vehicle width direction, and a gear for a cam chain is arranged on the right end side. Inside the cylinder block 10, four cylinders (cylinders) are formed (arranged) side by side in the vehicle width direction. A piston is slidably arranged up and down in the cylinder.

A cylinder head 11 in which an intake valve and an exhaust valve (both not shown) are housed is arranged above the cylinder block 10. The cylinder head 11 has a plurality of intake ports 11a (see FIG. 4) and a plurality of exhaust ports (not shown) provided corresponding to the cylinder. Four intake ports 11a are provided side by side in the vehicle width direction on the rear surface side of the vehicle. Four exhaust ports are provided side by side in the vehicle width direction on the front side of the vehicle.

A cylinder head cover 12 in which a part of the valve operating mechanism is housed is arranged above the cylinder head 11. An oil pan 13 for storing oil is arranged in the lower part of the cylinder block 10. Further, a cam chain chamber (not shown) in which a cam chain is arranged is formed on the right end side of the cylinder block 10 and the cylinder head 11. A gear cover 14 is arranged at the right end of the cylinder block 10 and the cylinder head 11 so as to close the cam chain chamber. The main housing portion of these engines may be referred to as an engine case or an engine body.

Further, on the front side of the cylinder head 11, exhaust manifolds 2 are connected to a plurality of exhaust ports. The exhaust manifold 2 has a flange portion 20 constituting a mounting portion for the cylinder head 11, four exhaust branch pipes 21ad extending from each of the four exhaust ports, and one on the downstream end side of the four exhaust branch pipes 21ad. It has a gathering unit 22 and a group 22 to be grouped together. The four exhaust branch pipes 21ad are indicated by reference numerals 21ad in order from the right side.

The flange portion 20 is formed of a plate-like body extending in the vehicle width direction facing the exhaust port. The upstream end of the exhaust branch pipe 21ad is connected to the flange portion 20 at a position corresponding to each exhaust port. The exhaust branch pipes 21ad project slightly forward from each exhaust port and then bend forward and downward. The collecting portion 22 is arranged so as to be biased to the left side when viewed from the front, and is located below the front of the exhaust branch pipe 21ad when viewed from the side.

More specifically, the gathering portion 22 is located below the exhaust branch pipe 21d on the left side and in front of the boundary portion between the cylinder block 10 and the cylinder head 11. The two exhaust branch pipes 21c and d on the left side are directly connected to the upstream side of the collecting portion 22. On the other hand, the exhaust branch pipe 21a on the right side is bent forward and downward, and then horizontally bent toward the left at the same height as the gathering portion 22. Then, the exhaust branch pipe 21a is connected to the side of the collecting portion 22 after being connected to the exhaust branch pipe 21b. As described above, the exhaust branch pipe 21b is connected to the horizontally bent exhaust branch pipe 21a after being bent forward and downward. As described above, the two exhaust branch pipes 21a and b on the right side have a longer exhaust flow path to the collecting portion 22 than the two exhaust branch pipes 21c and d located on the left side.

The exhaust manifold 2 is fixed to the cylinder head 11 by having the flange portion 20 face the exhaust port and bolting around each exhaust port. In the present embodiment, for example, as shown in FIG. 1, three exhaust branch pipes 21a-c on the right side are bolted to one exhaust port at one place. On the other hand, the exhaust branch pipe 21d on the left side is bolted at one place on the right side and two places on the left side up and down, for a total of three places.

An exhaust collecting pipe 3 is connected to the downstream end of the collecting portion 22. The exhaust collecting pipe 3 is composed of a catalyst portion 30 in which a catalyst (not shown) is arranged inside, and a tapered portion 31 which is continuous with the downstream end of the catalyst portion 30 and whose diameter is reduced. The catalyst unit 30 has a sufficiently large outer diameter as compared with the outer diameter of a single exhaust branch pipe. The catalyst unit 30 is inclined toward the outside (left side) of the vehicle as it goes downward in the front view (see FIG. 1), and is inclined toward the front of the vehicle as it goes downward in the side view. The catalyst unit 30 is arranged on the left front side of the cylinder block 10. The catalyst is composed of, for example, a three-way catalyst, and purifies by adsorbing pollutants (carbon monoxide, hydrocarbons, nitrogen oxides, etc.) in the exhaust gas and converting them into harmless substances (carbon dioxide, water, nitrogen, etc.). To do.

A fixing portion 32 for fixing the exhaust collecting pipe 3 at a predetermined position is provided on the outer surface of the catalyst portion 30. The fixing portion 32 is configured by bending both ends of a rectangular metal plate toward the outer surface of the catalyst portion 30 and welding the ends thereof to the outer surface of the catalyst portion 30.

The tapered portion 31 extends downward from the lower end of the catalyst portion 30, and the diameter is reduced toward the downstream. The tapered portion 31 is formed into a tubular shape by welding, for example, a pair of divided bodies divided in the vehicle width direction. The tapered portion 31 is arranged below the catalyst portion 30 and on the left front side of the cylinder block 10. A flange portion 33 for connecting the exhaust pipe 4 is welded to the lower end of the tapered portion 31. The flange portion 33 is formed of a ring-shaped plate member protruding radially outward from the lower end of the tapered portion 31. The flange portion 33 is located on the left front side of the engine body in the vicinity of the boundary portion between the cylinder block 10 and the oil pan 13 in front view.

The flange portion 33 is provided with a bracket 5 for fixing the lower end of the exhaust collecting pipe 3 to the engine body side. The bracket 5 is formed in a substantially L-shape in side view by bending or welding a metal plate. One end of the bracket 5 is bolted to the upper surface of the flange portion 33, and the other end of the bracket 5 is bolted to the front lower part of the cylinder block 10. In this way, the exhaust manifold 2 and the exhaust collecting pipe 3 are integrally fixed to the engine body. Specifically, the upstream end of the exhaust manifold 2 is fixed to the cylinder head 11 via the flange portion 20, and the downstream end of the exhaust collecting pipe 3 is fixed to the cylinder block 10 via the bracket 5.

By the way, the exhaust manifold of an internal combustion engine is a component that is exposed to a very high temperature due to exhaust heat. For this reason, conventionally, a dedicated cover (heat insulation sound insulation cover) is provided on the exhaust manifold for the purpose of heat insulation and sound insulation to the surroundings. The heat and sound insulation cover is formed so as to cover the entire outer surface shape of the exhaust manifold.

However, if the entire exhaust manifold is covered with the heat insulation and sound insulation cover, the heat of the exhaust manifold can be prevented from diffusing to the surroundings, but the heat tends to be trapped between the exhaust manifold and the heat insulation and sound insulation cover. As a result, there is a problem that the exhaust manifold is thermally deformed and causes plastic strain particularly at the connection portion with the cylinder head.

Further, since the exhaust gas immediately after the combustion of the air-fuel mixture flows into the exhaust manifold, thermal expansion occurs in the exhaust manifold while the engine is being driven. On the other hand, when the engine is stopped, the exhaust gas does not flow into the exhaust manifold, so that the exhaust manifold gradually contracts to return to its original shape. When thermal expansion and contraction are repeated in this way, plastic strain tends to accumulate and increase in the mounting portion with respect to the cylinder head.

In the exhaust device in which the exhaust manifold 2 and the exhaust collecting pipe 3 are integrated as in the above-described embodiment, the upstream end of the exhaust manifold 2 is fixed to the cylinder head 11 via the flange portion 20, and the exhaust collecting pipe 3 The downstream end is fixed to the cylinder block 10 via the bracket 5. By fixing the upstream end and the downstream end of the exhaust device to the engine body in this way, movement due to deformation in the vicinity of the fixed portion is restricted. That is, the exhaust manifold 2 and the exhaust collecting pipe 3 expand forward and upward so as to be separated from the engine body (cylinder block 10 and cylinder head 11) in the side view shown in FIG. 3, and in the top view shown in FIG. , Expands outward in the vehicle width direction (left-right direction). As a result, of the plurality of exhaust branch pipes 21a-d arranged in parallel, relatively large plastic strain may occur on the upstream end side of the two exhaust branch pipes 21a and d on both outer sides.

Therefore, the present inventors have focused on the fact that a relatively large plastic strain occurs in the vicinity of the exhaust ports arranged corresponding to the cylinders on both outer sides in the exhaust manifold of the parallel multi-cylinder engine, and came up with the present invention. .. Specifically, in the present embodiment, the reinforcing member 6 for reinforcing the exhaust manifold 2 extends in the direction of arranging the cylinders so as to cover the upstream end side of the four exhaust branch pipes 21. Of the four exhaust branch pipes 21ad, fixing portions 23 for fixing the ends of the reinforcing members 6 are provided on the upstream end sides of the two exhaust branch pipes 21a and d arranged on both ends. ..

According to this configuration, by connecting the two outer exhaust branch pipes 21a and d, which are relatively easily deformed, with a reinforcing member, it is possible to suppress the deformation of the exhaust manifold 2 due to thermal expansion and contraction. .. Further, the reinforcing member 6 covers the front upper part on the upstream end side of the exhaust branch pipe 21ad. As described above, the exhaust branch pipe 21ad can move forward and upward and outward in the vehicle width direction due to thermal expansion. In this way, by arranging the reinforcing members 6 facing each other in the direction in which the exhaust branch pipes 21ad can move due to thermal expansion, it is possible to suppress the deformation of the exhaust branch pipes 21ad and the movement due to the deformation. is there. Further, since the reinforcing member 6 does not cover the entire exhaust manifold 2 but a part of the exhaust branch pipe 21ad, it is difficult for heat to be trapped between the reinforcing member 6 and the exhaust manifold 2. As described above, it is possible to suppress the thermal deformation of the exhaust manifold.

Next, with reference to FIGS. 1 to 7, the exhaust structure of the internal combustion engine according to the present embodiment, particularly the fixed configuration of the reinforcing member will be described in detail. FIG. 5 is a diagram in which the reinforcing member is omitted in the internal combustion engine of FIG. FIG. 6 is a diagram in which the reinforcing member is omitted in the internal combustion engine of FIG. FIG. 7 is a single view of the reinforcing member according to the present embodiment. FIG. 7A is a developed view of the reinforcing member, and FIG. 7B is a front view of the reinforcing member.

As shown in FIGS. 5 and 6, the fixing portion 23 is formed in a substantially U-shape in side view by bending both ends of the rectangular metal plate toward the outer surfaces of the exhaust branch pipes 21a and d. Both ends of the bent fixing portion 23 are welded to the outer surfaces of the exhaust branch pipes 21a and d. As a result, the fixed portion 23 is formed with a flat plate-shaped facing portion 24 facing the outer surfaces of the exhaust branch pipes 21a and d. A screw hole 25 penetrating in the thickness direction is formed in the center of the facing portion 24.

The fixing portion 23 is arranged so as to be inclined toward the outside of the exhaust branch pipes 21a and d, respectively. Specifically, the fixing portion 23 located on the right side is arranged on the outer surface of the bent portion bent forward and downward on the upstream end side of the exhaust branch pipe 21a. The surface (upper surface) of the facing portion 24 is oriented in a direction of inclining upward to the right front. On the other hand, the fixing portion 23 located on the left side is arranged on the outer surface of the bent portion bent forward and downward on the upstream end side of the exhaust branch pipe 21d. The surface (upper surface) of the facing portion 24 is directed in a direction of inclining upward to the left front.

Although details will be described later, the distance L1 between the connecting portion (flange portion 20) and the fixing portion 23 (screw hole 25) of the exhaust branch pipe 21ad with respect to the cylinder head 11 is the downstream end of the collecting portion 22 and the fixing portion. It is smaller than the distance L2 from 23 (screw hole 25).

Further, as shown in FIGS. 1 to 4, the reinforcing member 6 is formed by bending both ends of a long plate-like body extending in the vehicle width direction. Specifically, the reinforcing member 6 includes a flat portion 60 having a flat surface extending in the arrangement direction of the cylinders, and a bent portion 61 bent so as to face the fixed portion 23 (opposing portion 24) from both ends of the flat portion 60. Have.

In particular, as shown in FIG. 7, the bending line L of the reinforcing member 6, which is the boundary between the flat portion 60 and the bent portion 61, extends back and forth so as to intersect the longitudinal direction of the reinforcing member 6. More specifically, the pair of left and right bending lines L are inclined inward in the vehicle width direction from the rear of the vehicle to the front. Further, the bent portion 61 is formed with a through hole 62 penetrating in the thickness direction at a position corresponding to the screw hole 25 of the facing portion 24.

In the reinforcing member 6 configured in this way, a pair of left and right bent portions 61 are arranged so as to face the facing portions 24, a bolt B is inserted into each through hole 62, and the tip of the bolt B is screwed into the screw hole 25. It can be attached by.

When the reinforcing member 6 is attached to the exhaust manifold 2, the flat portion 60 is arranged so as to cover the upper side of the upstream end side of the two inner exhaust branch pipes 21b and c among the four exhaust branch pipes 21ad. ing. The bent portion 61 on the right side is arranged so as to cover the upper side of the upstream end side of the exhaust branch pipe 21a on the right side. The bent portion 61 on the left side is arranged so as to cover the upper side of the upstream end side of the exhaust branch pipe 21d on the left side. Further, the flat portion 60 is located above the fixed portion 23 in the front view. Further, the flat portion 60 is located at substantially the same height as the upper end of the flange portion 20.

In the exhaust structure of the internal combustion engine configured as described above, since the reinforcing member 6 is formed of a plate-shaped elongated body, the material yield is improved. Further, since the reinforcing member 6 is formed only by bending both ends of the plate-shaped elongated body, the manufacturing process is simplified. As a result, the reinforcing member 6 can be manufactured at low cost. Further, since the reinforcing member 6 has a simple plate-like structure, it is possible to increase the rigidity of the exhaust manifold 2 with a simple configuration. Therefore, it is not necessary to form the exhaust manifold 2 itself to be thick in order to secure the rigidity, and the weight of the exhaust manifold 2 can be reduced.

Further, since the fixing portion 23 is formed by bending both ends in the front-rear direction, the rigidity in the left-right direction is increased. Further, since the bending line L of the reinforcing member 6 is inclined and extends so as to intersect the longitudinal direction of the reinforcing member 6, both the front-rear direction which is the lateral direction of the reinforcing member 6 and the left-right direction which is the longitudinal direction are both directions. Therefore, the rigidity of the reinforcing member 6 itself is increased.

Further, the collecting portion 22 of the exhaust manifold 2 is arranged unevenly on the left side, which is one side in the vehicle width direction, with respect to the center of the engine body in the vehicle width direction. Further, the exhaust collecting pipe 3 connected to the collecting portion 22 is also unevenly arranged on the left side of the engine body. Therefore, the center of gravity of the exhaust device including the exhaust manifold 2 and the exhaust collecting pipe 3 is biased to the left side in the vehicle width direction with respect to the engine body. Correspondingly, the number of bolt fastening points is increased to three around the exhaust branch pipe 21d on the left end side of the flange portion 20. In this way, by partially increasing the number of fastening points of the flange portion 20 in consideration of the weight balance of the exhaust device, the exhaust device can be stably fixed to the cylinder head 11.

Further, in the present embodiment, the four exhaust branch pipes 21ad are bent downward from the exhaust port. The reinforcing member 6 is arranged so as to cover the upper part of the bent portion of the four exhaust branch pipes 21ad. According to this configuration, since the reinforcing member 6 is provided at a position where the four exhaust branch pipes 21ad can be thermally expanded and moved, the deformation of the exhaust branch pipe 21ad and the movement due to the deformation are effectively suppressed. It is possible to do.

Further, the distance L1 between the flange portion 20 and the fixing portion 23 is smaller than the distance L2 between the downstream end of the gathering portion 22 and the fixing portion 23. According to this configuration, the reinforcing member 6 can be arranged on the upstream end side of the exhaust branch pipe 21ad, and the rigidity of the upstream end side of the exhaust branch pipe 21ad which easily expands thermally can be effectively increased. Is possible.

Further, the flat portion 60 is located above the fixed portion 23. Further, the flat portion 60 covers the upper part of the two exhaust branch pipes 21b and c arranged inside among the four exhaust branch pipes 21ad. Further, the bent portion 61 covers the upper part of the two exhaust branch pipes 21a and d arranged on both end sides of the four exhaust branch pipes 21ad. According to these configurations, the reinforcing member 6 can be arranged away from the exhaust branch pipes 21ad while increasing the rigidity of the exhaust manifold 2. Therefore, a gap between the reinforcing member 6 and the exhaust branch pipe 21ad is secured, and it is possible to improve the ventilation of the gap. As a result, it is possible to prevent heat from being trapped between the exhaust branch pipe 21ad and the reinforcing member 6, and to suppress the occurrence of further plastic strain in the exhaust manifold 2.

As described above, according to the present embodiment, in the exhaust manifold 2 of the parallel multi-cylinder engine, of the plurality of exhaust branch pipes 21ad, the two exhaust branch pipes 21a and d arranged on both ends are provided. By providing the reinforcing member 6 so as to be connected and arranging the reinforcing member 6 so as to cover the upstream end side of the exhaust branch pipe 21ad, it is possible to suppress thermal deformation of the exhaust manifold 2 with a simple configuration. is there.

In the above embodiment, in the in-line 4-cylinder engine, an exhaust manifold 2 in which an exhaust port is arranged for each cylinder and four exhaust branch pipes 21ad are provided corresponding to each exhaust port will be described as an example. However, it is not limited to this configuration. The number of cylinders of the engine may be at least three. Similarly, there may be at least three exhaust ports and three exhaust branch pipes.

Further, in the above embodiment, the case where the engine arrangement is the FR layout has been described, but the present invention is not limited to this configuration. The arrangement of the engines may be, for example, an FF layout.

Further, in the above embodiment, the case where the reinforcing member 6 is formed by bending both ends of the plate-shaped elongated body has been described, but the present invention is not limited to this configuration. The reinforcing member 6 may have a shape that is entirely curved, for example.

Further, in the above embodiment, the case where the fixing portion 23 is formed by bending the metal plate has been described, but the present invention is not limited to this configuration. The fixing portion 23 may be formed by welding a metal block (block body) to the exhaust branch pipe.

Further, in the above embodiment, the case where the gathering portion 22 is unevenly arranged on the left side in the vehicle width direction has been described, but the present invention is not limited to this configuration. The gathering portion 22 may be arranged unevenly on the right side or may be arranged in the center of the engine body.

Further, in the above embodiment, the case where the reinforcing member 6 is fixed to the exhaust manifold 2 by the bolt B has been described, but the present invention is not limited to this configuration. The reinforcing member 6 may be fixed to the exhaust manifold 2 by welding.

In addition, although a plurality of embodiments and modifications have been described, other embodiments of the present invention may be a combination of the above embodiments and modifications in whole or in part.

Further, the embodiment of the present invention is not limited to the above-described embodiment, and may be variously modified, replaced, or modified without departing from the spirit of the technical idea of the present invention. Furthermore, if the technical idea of the present invention can be realized in another way by the advancement of the technology or another technology derived from it, it may be carried out by using that method. Therefore, the scope of claims covers all embodiments that may be included within the scope of the technical idea of the present invention.

As described above, the present invention has the effect of suppressing thermal deformation of the exhaust manifold, and is particularly useful for the exhaust structure of an internal combustion engine.

1: Engine 2: Exhaust manifold 3: Exhaust collecting pipe 4: Exhaust pipe 5: Bracket 6: Reinforcing member 10: Cylinder block 11: Cylinder head 11a: Intake port 12: Cylinder head cover 13: Oil pan 14: Gear cover 20: Flange 21ad: Exhaust branch pipe 22: Collecting part 23: Fixed part 24: Facing part 25: Screw hole 30: Catalyst part 31: Tapered part 32: Fixed part 33: Flange part 60: Flat part 61: Bending part 62: Penetration Hole B: Bolt L: Bending line

Claims (6)

The exhaust structure of an internal combustion engine in which at least three cylinders are arranged in parallel.
A cylinder head having a plurality of exhaust ports provided corresponding to the cylinder,
Exhaust manifolds connected to the plurality of exhaust ports and
A reinforcing member for reinforcing the exhaust manifold is provided.
The exhaust manifold
A plurality of exhaust branch pipes extending from the plurality of exhaust ports and
A gathering part that brings together the downstream end sides of the plurality of exhaust branch pipes,
It has a fixing portion for fixing the reinforcing member and
The fixing portion is provided on the upstream end side of each of the two exhaust branch pipes arranged on both end sides of the plurality of exhaust branch pipes.
The reinforcing member extends in the arrangement direction of the cylinders so as to cover the upstream end side of the plurality of exhaust branch pipes, and each end is fixed to the fixed portion of the exhaust gas of the internal combustion engine. Construction. The plurality of exhaust branch pipes are bent downward from the exhaust port.
The exhaust structure of an internal combustion engine according to claim 1, wherein the reinforcing member is arranged so as to cover the upper part of the bent portion of the plurality of exhaust branch pipes. Further having an exhaust collecting pipe connected to the downstream end of the collecting part,
The exhaust structure of an internal combustion engine according to claim 1 or 2, wherein the downstream end of the exhaust collecting pipe is fixed to the engine body by a bracket. Claims 1 to 3 are characterized in that the distance between the connection portion of the plurality of exhaust branch pipes to the cylinder head and the fixed portion is smaller than the distance between the downstream end of the collecting portion and the fixed portion. The exhaust structure of the internal combustion engine according to any one of. The fixed portion is arranged so as to be inclined toward the outside of the exhaust branch pipe.
The reinforcing member is
A flat portion having a flat surface extending in the alignment direction of the cylinders
It has bent portions bent so as to face the fixed portion from both ends of the flat portion.
The exhaust structure of an internal combustion engine according to any one of claims 1 to 4, wherein the flat portion is located above the fixed portion. The flat portion covers the upper part of the exhaust branch pipe arranged inside among the plurality of exhaust branch pipes.
The exhaust structure of an internal combustion engine according to claim 5, wherein the bent portion covers the upper part of two exhaust branch pipes arranged on both end sides of the plurality of exhaust branch pipes.

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