WO2014196279A1

WO2014196279A1 - Engine

Info

Publication number: WO2014196279A1
Application number: PCT/JP2014/061046
Authority: WO
Inventors: 小原　徹也; 濱本　高行
Original assignee: 日産自動車株式会社
Priority date: 2013-06-03
Filing date: 2014-04-18
Publication date: 2014-12-11

Abstract

This engine is provided with: a cylinder head which has exhaust ports formed in each of four cylinders, said exhaust ports being an aggregate exhaust port, wherein two exhaust ports with non-continuous ignition order are aggregated, and two independent exhaust ports, which are the remaining two exhaust ports, and all three exhaust ports, i.e. the aggregate exhaust port and the two independent ports, being formed in the lateral surface of the cylinder head; a catalyst device for purifying harmful components in the exhaust; and an exhaust manifold for connecting the catalyst device and the three exhaust ports formed in the lateral surface of the cylinder head. The exhaust manifold is provided with three exhaust passages partitioned by a partition wall formed inside of the exhaust manifold in order to guide the exhaust discharged from the three exhaust ports to the catalyst device.

Description

engine

The present invention relates to an engine (internal combustion engine), and more particularly to a structure of an exhaust manifold that connects a cylinder head and a catalyst device.

In the in-line four-cylinder engine disclosed in JP2009-30555A, the exhaust ports of the # 2 and # 3 cylinders whose firing order is not continuous are gathered into one inside the cylinder head, and this gathered exhaust port, and Three exhaust ports of the two independent exhaust ports of the # 1 cylinder and the # 4 cylinder were opened at one end surface of the cylinder head. Then, engine exhaust is introduced into the catalyst device via an exhaust manifold connected to three exhaust ports opened at one end face of the cylinder head.

Here, the exhaust manifold is structured so that the exhaust from the collected exhaust ports and the exhaust from the two independent exhaust ports of the # 1 cylinder and # 4 cylinder are immediately gathered in the exhaust manifold. If this happens, there is a risk of exhaust interference. However, JP2009-30555A does not disclose any structure of the exhaust manifold.

The present invention has been made paying attention to such problems, and an object thereof is to provide an engine capable of reducing interference of exhaust.

An engine according to an aspect of the present invention includes an exhaust port that is opened to each of four cylinders, and an exhaust port that collects two exhaust ports that do not have an ignition sequence inside, and the remaining two independent independent exhausts. A cylinder head having three exhaust ports of a collective exhaust port and two independent exhaust ports open on the side surface, a catalyst device for purifying harmful components in the exhaust, and a side surface of the cylinder head An exhaust manifold for connecting the three exhaust ports opened to the catalyst device and the catalyst device. The exhaust manifold includes three exhaust passages partitioned by partition walls formed inside the exhaust manifold in order to guide the exhaust discharged from the three exhaust ports to the catalyst device.

FIG. 1 is a schematic plan view of a cylinder head according to a first embodiment of the present invention. FIG. 2 is a side view of the cylinder head on the side where the exhaust port opens. FIG. 3 is a schematic perspective view of the catalyst device and the exhaust manifold according to the first embodiment of the present invention. FIG. 4 is a schematic cross-sectional view of the exhaust manifold and the catalyst device viewed from the lateral side of the cylinder head according to the first embodiment of the present invention. FIG. 5 is a schematic cross-sectional view of a collection portion of the exhaust manifold according to the first embodiment of the present invention. FIG. 6 is a schematic cross-sectional view of the exhaust manifold and the catalyst device as seen from the lateral side of the cylinder head according to the second embodiment of the present invention. FIG. 7 is a schematic cross-sectional view of a collection portion of the exhaust manifold according to the second embodiment of the present invention. FIG. 8 is a schematic cross-sectional view of the exhaust manifold and the catalyst device viewed from the lateral side of the cylinder head according to the third embodiment of the present invention. FIG. 9 is a schematic cross-sectional view of a collection portion of the exhaust manifold according to the third embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
First, an engine 1 according to a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a schematic plan view of a cylinder head 2 according to a first embodiment of the present invention, showing a cylinder 3, an intake port 4, and an exhaust port 5 seen through. FIG. 2 is a side view of the cylinder head 2 on the side where the exhaust port opens. FIG. 3 is a schematic perspective view of the exhaust manifold 11 and the catalyst device 31 according to the first embodiment of the present invention. FIG. 4 is a schematic cross-sectional view of the exhaust manifold 11 and the catalyst device 31 as viewed from the side surface in the short direction of the cylinder head 2. FIG. 5 is a schematic cross-sectional view of the collecting portion 15 of the exhaust manifold 11.

As shown in FIG. 1, the engine 1 is an in-line four-cylinder engine having four valves per cylinder. The number of valves per cylinder is not limited to four, but at least one valve for intake and one for exhaust may be used.

The engine 1 includes four cylinders 3 formed in a line along the longitudinal direction of a rectangular parallelepiped cylinder head 2, four intake ports 4 and four exhaust ports 5 formed corresponding to each cylinder 3, Is provided.

In the following description, when it is necessary to distinguish each cylinder 3, each cylinder 3 will be referred to as # 1 cylinder 3A, # 2 cylinder 3B, # 3 cylinder 3C, # 4 cylinder 3D in order from the left in the figure. . When the exhaust ports 5 need to be distinguished from each other, the exhaust ports 5 will be referred to as an exhaust port 5A, an exhaust port 5B, an exhaust port 5C, and an exhaust port 5D in order from the left in the drawing.

The engine 1 is ignited in the order of # 1 cylinder 3A- # 2 cylinder 3B- # 4 cylinder 3D- # 3 cylinder 3C, and generates power for driving a vehicle, for example.

The intake port 4 is formed inside the cylinder head 2. The intake port 4 has one end branched into two branches and opened to the cylinder 3, and the other end opened to one side surface 2 A in the longitudinal direction of the cylinder head 2. The opening of the intake port 4 and the cylinder 3 is opened and closed by an intake valve.

The exhaust port 5 is formed inside the cylinder head 2.

Of these, the two

exhaust ports

5A and 5D formed at both ends of the cylinder head 2 have one end bifurcated to open to the

cylinders

3A and 3D, respectively, and the other end to the other of the cylinder head 2 in the longitudinal direction. It opens to the side surface 2B. As described above, the exhaust ports 5 A and 5 D are independent inside the cylinder head 2 without gathering with the other exhaust ports 5 inside the cylinder head 2. Therefore, in the following description, the

exhaust ports

5A and 5D are referred to as “independent exhaust ports” as necessary.

On the other hand, the two

exhaust ports

5B and 5C formed at the center of the cylinder head 2 are bifurcated at one end side and open to the

cylinders

3B and 3C, respectively, but the other end is inside the cylinder head 2 Are opened in the other side surface 2B in the longitudinal direction of the cylinder head 2 after being assembled together. That is, an end portion of an exhaust port (hereinafter referred to as “collected exhaust port”) 6 in which the

exhaust ports

5B and 5C are gathered into one is opened on the other side surface 2B in the longitudinal direction of the cylinder head 2.

Therefore, as shown in FIG. 2, the exhaust ports that open to the side surface 2B of the cylinder head 2, in other words, the side surface 2B on the exhaust port side of the cylinder head 2, are the independent exhaust port 5A, the collective exhaust port 6, the independent exhaust port. Three 5D. Further, the opening area of the collective exhaust port 6 that opens to the side surface 2B of the cylinder head 2 is larger than the opening area of the

independent exhaust ports

5A and 5D that open to the side surface 2B of the cylinder head 2.

If the

exhaust ports

5B and 5C are aggregated into one, exhaust interference becomes a problem, but in the present embodiment, the ignition order of the engine 1 is # 1 cylinder 3A- # 2 cylinder 3B- # 4. The order is cylinder 3D- # 3 cylinder 3C. Therefore, explosions are repeated at intervals of 360 [° CA] in the # 2 cylinder 3B and the # 3 cylinder 3C. In other words, the crank angle is 360 degrees apart between the explosion timing in the # 2 cylinder 3B and the explosion timing in the # 3 cylinder 3C. Therefore, even if the exhaust port 5B of the # 2 cylinder 3B and the exhaust port 5C of the # 3 cylinder 3C are gathered together in the cylinder head 2, no interference of exhaust occurs.

Thus, in the present embodiment, the

exhaust ports

5B and 5C that do not cause exhaust interference are gathered together in the cylinder head 2. According to the configuration of the present embodiment, the exhaust manifold is entirely outside the cylinder head, that is, the exhaust manifold having four branch pipes without collecting a part of the exhaust ports in the cylinder head. Compared to the configuration connected to the cylinder head, the overall length of the exhaust manifold can be shortened by assembling a part of the exhaust ports in the cylinder head, and the length of the exhaust passage from the cylinder head 2 to the catalyst device 31 is shortened. can do. As a result, when the engine 1 is cold started, the temperature of the exhaust discharged from the cylinder head 2 can be prevented from decreasing while passing through the exhaust manifold, so that the catalyst 35 can be activated early.

Further, according to the configuration of the present embodiment, since the entire length of the exhaust manifold can be shortened, the amount of heat escaping to the outside through the exhaust manifold can be reduced, so that the amount of heat escaping from the engine 1 can be reduced. Therefore, warm-up of the engine 1 can be completed early at the time of cold start.

Next, when designing the exhaust manifold 11 connected to the cylinder head 2 having the three exhaust ports of the

independent exhaust ports

5A and 5D and the collective exhaust port 6, there is an interference of exhaust within the exhaust manifold 11. It is required not to occur. Further, considering the mountability of the engine 1 on a vehicle or the like, it is also required to design the exhaust manifold 11 to be compact overall.

Therefore, in the present embodiment, the exhaust manifold 11 for guiding the exhaust discharged from the three exhaust ports of the

independent exhaust ports

5A and 5D and the collective exhaust port 6 to the inlet of the catalyst device 31 is replaced with the first branch portion 12. And a second branching section 13, a third branching section 14, and a collecting section 15.

The first branch portion 12, the second branch portion 13, and the third branch portion 14 of the exhaust manifold 11 are each provided with an independent exhaust port 5 A that opens to the side surface 2 B of the cylinder head 2 via a gasket 7 (see FIG. 3). Connected to the exhaust port 6 and the independent exhaust port 5D.

The collecting portion 15 of the exhaust manifold 11 is formed by collecting the first branch portion 12, the second branch portion 13, and the third branch portion 14 together, and is connected to the catalyst device 31.

The catalyst device 31 includes a cylindrical central portion 32, an upstream cone portion 33, and a downstream cone portion 34.

Inside the central portion 32, a catalyst 35 (see FIG. 4) such as a three-way catalyst is accommodated.

The upstream cone portion 33 is connected to the collecting portion 15 of the exhaust manifold 11. The upstream end 33A of the upstream cone portion 33 is circular. In order to smoothly connect the collecting portion 15 of the exhaust manifold 11 to the circular upstream end 33A, the downstream side of the collecting portion 15 is cylindrical. Further, a hole 36 (see FIG. 3) for attaching the air-fuel ratio sensor is formed in the upstream cone portion 33.

In FIG. 1, the catalyst device 31 is arranged in a plane in order to show the overall connection between the exhaust manifold 11 and the catalyst device 31, but this is not the case. Exhaust gas from the engine 1 passes under the floor of the vehicle on which the engine 1 is mounted, and then flows toward the rear of the vehicle. Therefore, as shown in FIG. 4, the catalyst device 31 is basically arranged in the vertical direction so that the exhaust gas flowing through the collecting portion 15 of the exhaust manifold 11 is directed downward in the vertical direction. More specifically, as shown in FIG. 3, the catalyst device 31 is disposed slightly tilted from the vertical direction.

Further, in FIG. 1, it seems that the exhaust discharged from the three exhaust ports of the independent exhaust port 5A, the collective exhaust port 6 and the independent exhaust port 5D is immediately gathered inside the exhaust manifold 11. is not. In the present embodiment, in order to avoid exhaust interference that occurs when exhaust is immediately collected inside the exhaust manifold 11, the three exhaust ports of the independent exhaust port 5A, the collective exhaust port 6 and the independent exhaust port 5D are used. The discharged exhaust is not immediately collected inside the exhaust manifold 11.

In the present embodiment, as shown in FIGS. 4 and 5, three partition walls of a first partition wall 21, a second partition wall 22, and a third partition wall 23 are provided inside the exhaust manifold 11.

By these three partition walls, three exhaust passages (the first exhaust passages) that respectively lead the exhaust discharged from the three exhaust ports of the independent exhaust port 5A, the collective exhaust port 6 and the independent exhaust port 5D to the inlet of the catalyst device 31 independently. An exhaust passage 24, a second exhaust passage 25 and a third exhaust passage 26) are formed inside the exhaust manifold 11. As described above, the exhaust manifold 11 joins the exhaust gases independently discharged from the first exhaust passage 24, the second exhaust passage 25, and the third exhaust passage 26 at the inlet of the catalyst device 31 and introduces them into the catalyst device 31. It is configured.

This prevents the exhaust exhausted from the

independent exhaust ports

5A and 5D and the exhaust exhausted from the collective exhaust port 6 from interfering with each other inside the exhaust manifold 11.

Hereinafter, the three exhaust passages (the first exhaust passage 24, the second exhaust passage 25, and the third exhaust passage 26) formed inside the exhaust manifold 11 will be described in detail with reference to FIGS.

As shown in FIG. 4, the first exhaust passage 24 is a passage for guiding the exhaust discharged from the collective exhaust port 6 to the catalyst device 31, and is curved after rising obliquely upward in the vertical direction. Thus, it is formed so as to be directed downward in the vertical direction.

4 and FIG. 5, the downstream side of the first exhaust passage 24 is disposed on a relatively far side when viewed from the cylinder head 2.

That is, as shown in FIG. 5, the first partition wall 21 and the second partition wall 22 are arranged on the same surface on the downstream side of the collecting portion 15 of the exhaust manifold 11. Then, by the first partition wall 21 and the second partition wall 22 arranged side by side, the passage sectional area on the downstream side of the collecting portion 15 is divided into two equal parts, a relatively far side and a near side when viewed from the cylinder head 2, and the cylinder head The side far from 2 is the first exhaust passage 24.

In FIG. 5, the cross section of the collecting portion 15 of the exhaust manifold 11 is seen through from above, and the cylinder head 2 is placed at a position slightly away from the collecting portion 15 of the exhaust manifold 11 in the horizontal direction. .

The second exhaust passage 25 is a passage for guiding the exhaust discharged from the independent exhaust port 5A to the catalyst device 31. The third exhaust passage 26 is a passage for guiding the exhaust discharged from the independent exhaust port 5D to the catalyst device 31. As shown in FIG. 4, the second exhaust passage 25 and the third exhaust passage 26 are formed so as to bend downward in the vertical direction after extending in the horizontal direction.

As shown in FIGS. 4 and 5, the downstream side of the second exhaust passage 25 is located closer to the cylinder head 2 and closer to the # 1 cylinder 3A (left side in FIG. 5). Deploy. Further, the downstream side of the third exhaust passage 26 is disposed on the side relatively close to the cylinder head 2 and on the side close to the # 4 cylinder 3D (the right side in FIG. 5).

That is, as shown in FIG. 5, of the two passages inside the collecting portion 15 divided into two equal parts by the first partition wall 21 and the second partition wall 22, the passage on the side relatively close to the cylinder head 2 is cut off. The area is divided into two equal parts by the third partition wall 23, and the side close to the # 1 cylinder 3A is the second exhaust passage 25, and the side close to the # 4 cylinder 3D is the third exhaust passage 26.

As described above, in the present embodiment, the first exhaust passage 24 through which the exhaust discharged from the collective exhaust port 6 flows is disposed on a relatively far side when viewed from the cylinder head 2 and is discharged from the

independent exhaust ports

5A and 5D. The second exhaust passage 25 and the third exhaust passage 26 through which the exhaust flows are arranged on the relatively close side when viewed from the cylinder head 2.

This is because the exhaust of two cylinders is introduced into the first exhaust passage 24, and therefore the surface area of the first exhaust passage per exhaust amount flowing through the first exhaust passage 24, the second exhaust passage 25 and the third exhaust passage. Comparing the surface areas of the second exhaust passage 25 and the third exhaust passage 26 per exhaust amount flowing through the first exhaust passage 26, the surface area of the first exhaust passage per exhaust amount flowing through the first exhaust passage 24 is greater. The first exhaust passage 24 is smaller in heat dissipation than the second exhaust passage 25 and the third exhaust passage 26.

Therefore, the first exhaust passage 24 is arranged on a relatively far side when viewed from the cylinder head 2, and the length of the passage through which the exhaust discharged from the collective exhaust port 6 flows is discharged from the

independent exhaust ports

5A and 5D. The length of the exhaust passage is longer than the length of the passage through which the exhaust flows, and the amount of heat released from the first exhaust passage 24, the second exhaust passage 25, and the third exhaust passage 26 is made uniform to flow into the catalyst device 31 from each cylinder 3A-3D. This is to make the temperature of exhaust gas to be uniform. Further, by disposing the second exhaust passage 25 and the third exhaust passage 26 on the relatively close side when viewed from the cylinder head 2, heat radiation is suppressed from the exhaust flowing through the second exhaust passage 25 and the third exhaust passage 26. Therefore, it is possible to reduce heat loss at the time of engine cold start and promote early activation of the catalyst 35 of the catalyst device 31.

In the present embodiment, as shown in FIG. 5, when the cross-sectional area S2 of the second exhaust passage 25 and the cross-sectional area S3 of the third exhaust passage 26 are 1, the cross-sectional area S1 of the first exhaust passage 24 is 2, the first exhaust passage 24, the second exhaust passage 25, and the third exhaust passage 26 are formed inside the exhaust manifold 11.

Actually, when the cross-sectional areas of the second exhaust passage 25 and the third exhaust passage 26 are all 1 from the upstream end to the downstream end of the exhaust manifold 11, the cross-sectional area of the first exhaust passage 24 is The exhaust manifold 11 having three first partition walls 21, second partition walls 22, and third partition walls 23 is designed so as to have a shape of 2.

Specifically, even if the cross-sectional area of the first exhaust passage 24 is twice the cross-sectional area of each of the second exhaust passage 25 and the third exhaust passage 26, the surface area per unit length of the first exhaust passage 24 is the second exhaust passage. 25 and the surface area per unit length of the third exhaust passage 26 is not doubled. Therefore, the surface area of the first exhaust passage 24 per flowing exhaust amount is smaller than that of the second exhaust passage 25 and the third exhaust passage 2. In other words, the second exhaust passage 25 and the third exhaust passage 26 have a surface area per flowing exhaust amount larger than that of the first exhaust passage 24.

Since the exhaust from the two cylinders # 2 cylinder 3B and # 3 cylinder 3A does not flow into the first exhaust passage 24 at the same time, the cross-sectional area of the first exhaust passage 24 is determined from the viewpoint of the flow path resistance. It is not necessary to double the cross-sectional area of 25 and the third exhaust passage 26. However, considering the distribution of the exhaust gas at the inlet of the catalyst device 31, the cross-sectional area of the first exhaust passage 24 is made twice the cross-sectional area of each of the second exhaust passage 25 and the third exhaust passage 26.

This is because the distribution of the exhaust gas at the inlet of the catalyst device 31 is equally divided. Thereby, the detection accuracy of the air-fuel ratio sensor attached to the hole 36 of the upstream cone portion 33 can be maintained.

Hereinafter, the function and effect of the engine 1 according to the present embodiment will be described.

The engine 1 according to the present embodiment includes a collective exhaust port 6 in which two

exhaust ports

5B and 5C that do not have a continuous ignition order among the exhaust ports 5A to 5D that respectively open to the four cylinders 3A to 3D are assembled. A cylinder head 2 having the remaining two independent

independent exhaust ports

5A and 5D, and the three exhaust ports of the collective exhaust port 6 and the two

independent exhaust ports

5A and 5D open on the side surface; A catalyst device 31 for purifying harmful components in the exhaust, and an exhaust manifold 11 for connecting the three

exhaust ports

6, 5A, 5D opened in the side surface of the cylinder head 2 to the catalyst device 31. Prepare.

Then, in order to individually guide the exhaust discharged from the three

exhaust ports

6, 5A, 5D to the catalyst device 31, three exhaust passages 24 partitioned by the partition walls 21-23 inside the exhaust manifold 11. -26 was formed.

Thereby, the exhaust pulsation of the two

cylinders

3B and 3C discharged from the collective exhaust port 6 can be reduced. Further, the exhaust interference between the exhaust discharged from the collective exhaust port 6 and the exhaust discharged from the two independent exhaust ports 5A and 5d can be reduced. Therefore, exhaust gas remaining in each cylinder 3A-3D can be reduced.

Further, since the surface area of the exhaust manifold 11 is smaller than that of the exhaust manifold having four branch pipes, the temperature of the catalyst device 31 can be raised earlier when the engine 1 is cold started.

Further, since the exhaust manifold 11 has three branch pipes, the exhaust manifold 11 itself becomes compact, and as a result, the entire engine 1 including parts (for example, the catalyst device 31) attached to the exhaust manifold 11 becomes compact. For this reason, for example, it can be mounted on a vehicle having limited vehicle space such as a 4WD specification vehicle.

Further, in the engine 1 according to the present embodiment, the first exhaust passage 24 in the exhaust manifold 11 through which the exhaust discharged from the collective exhaust port 6 flows is disposed on a relatively far side when viewed from the cylinder head 2, and independent exhaust is performed. Two exhaust passages (the second exhaust passage 25 and the third exhaust passage 26) in the exhaust manifold 11 through which the exhaust discharged from the

ports

5A and 5D flows are disposed on a relatively close side when viewed from the cylinder head 2. The

As a result, the temperature of the exhaust gas flowing into the catalyst device 31 from each cylinder 3A-3D can be made uniform, so that heat loss during cold start of the engine can be reduced, and the catalyst 35 housed in the catalyst device 31 can be reduced. Early activation can be promoted.

In the engine 1 according to the present embodiment, each of the two exhaust passages (the second exhaust passage 25 and the third exhaust passage 26) in the exhaust manifold 11 through which the exhaust discharged from the independent exhaust port flows has a cross-sectional area of 1 In this case, the cross-sectional area of the first exhaust passage 24 in the exhaust manifold 11 through which the exhaust discharged from the collective exhaust port 6 flows is 2.

Thereby, the distribution of the exhaust gas at the inlet of the catalyst device 31 is equally divided, and the detection accuracy of the air-fuel ratio sensor provided in the upstream cone portion 33 can be maintained.

(Second Embodiment)
Next, an engine 1 according to a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the first exhaust passage 24 is disposed on a relatively close side when viewed from the cylinder head 2, and the second exhaust passage 25 and the third exhaust passage 26 are disposed on a relatively far side when viewed from the cylinder head 2. It differs from the first embodiment in that it is arranged. Hereinafter, the difference will be mainly described. In each of the following embodiments, the same reference numerals are used for portions that perform the same functions as those of the first embodiment described above, and repeated descriptions are omitted as appropriate.

FIG. 6 is a schematic view of the exhaust manifold 11 and the catalyst device 31 as viewed from the lateral side of the cylinder head 2 according to the second embodiment of the present invention. FIG. 7 is a schematic cross-sectional view of the collecting portion 15 of the exhaust manifold 11 according to the second embodiment of the present invention.

In this embodiment, as shown in FIG. 6, the first exhaust passage 24 is formed so as to extend downward in the horizontal direction and then bend downward in the vertical direction. Then, as shown in FIGS. 6 and 7, the downstream side of the first exhaust passage 24 is disposed on a relatively close side when viewed from the cylinder head 2.

That is, in the present embodiment, as shown in FIG. 7, the first partition wall 21 and the second partition wall 22 cause the passage cross-sectional area on the downstream side of the collecting portion 15 to be relatively far and closer to the side as viewed from the cylinder head 2. A side that is relatively close to the cylinder head 2 when divided into two equal parts is defined as a first exhaust passage 24.

In the present embodiment, as shown in FIG. 6, the second exhaust passage 25 and the third exhaust passage 26 are formed to extend in the horizontal direction and then bend downward in the vertical direction. Then, as shown in FIGS. 6 and 7, the downstream side of the second exhaust passage 25 is located on the side far from the cylinder head 2 and near the # 1 cylinder 3A (left side in FIG. 7). Deploy. Further, the downstream side of the third exhaust passage 26 is disposed on the side relatively far from the cylinder head 2 and on the side close to the # 4 cylinder 3D (the right side in FIG. 7).

That is, in the present embodiment, as shown in FIG. 7, of the two paths inside the collecting portion 15 divided into two equal parts by the first partition wall 21 and the second partition wall 22, the side relatively far from the cylinder head 2. Is divided into two equal parts by the third partition wall 23, and the side close to the # 1 cylinder 3A is referred to as a second exhaust passage 25, and the side close to the # 4 cylinder 3D is referred to as a third exhaust passage 26.

As described above, in the present embodiment, the first exhaust passage 24 is disposed on a relatively close side as viewed from the cylinder head 2, and the second exhaust passage 25 and the third exhaust passage 26 are relatively viewed from the cylinder head 2. Since it is arranged on the far side, it is not necessary to make the first exhaust passage 24 obliquely rise upward in the vertical direction and then bend downward in the vertical direction as in the first embodiment. . Therefore, the exhaust manifold 11 can be made more compact.

In the engine 1 according to the present embodiment described above, the first exhaust passage 24 in the exhaust manifold 11 through which the exhaust discharged from the collective exhaust port 6 flows is disposed on a relatively close side when viewed from the cylinder head 2 and is independent. Two exhaust passages (the second exhaust passage 25 and the third exhaust passage 26) in the exhaust manifold 11 through which the exhaust discharged from the

exhaust ports

5A and 5D flows are arranged on the relatively far side when viewed from the cylinder head 2. Is done.

Thereby, the exhaust manifold 11 can be made more compact.

(Third embodiment)
Next, an engine 1 according to a third embodiment of the present invention will be described with reference to FIGS. This embodiment is different from the first embodiment in that the second exhaust passage 25 and the third exhaust passage 26 are joined just before the entrance of the catalyst device 31. Hereinafter, the difference will be mainly described.

FIG. 8 is a schematic view of the exhaust manifold 11 and the catalyst device 31 as viewed from the lateral side of the cylinder head 2 according to the third embodiment of the present invention. FIG. 9 is a schematic cross-sectional view of the collecting portion 15 of the exhaust manifold 11 according to the third embodiment of the present invention.

In the first embodiment, the exhaust discharged from the collective exhaust port 6 and the

independent exhaust ports

5A and 5D is independently led to the inlet of the catalyst device 31 by the three exhaust passages 24-26.

On the other hand, in the present embodiment, the second exhaust passage 25 and the third exhaust passage 26 are gathered into one inside the gathering portion 15 of the exhaust manifold 11, and the exhaust discharged from the

independent exhaust ports

5A and 5D, respectively. Are guided independently until just before the entrance of the catalyst device 31.

As a specific configuration, a position where the partition wall 23 is formed is set to a position that enters the upstream side in the collecting portion 15 of the exhaust manifold 11 by a predetermined length from the inlet of the catalyst device 31, and from that position of the catalyst device 31. No partition wall 23 is provided between the entrances. For this reason, as shown in FIG. 8, the second exhaust passage 25 and the third exhaust passage 26 are gathered together on the downstream side where the partition wall 23 is removed to form a collective exhaust passage 27, and the collective exhaust passage 27 is formed in the catalyst device 31. Will be connected to.

That is, as shown in FIG. 9, on the downstream side of the collecting portion 15 of the exhaust manifold 11, the first partition wall 21 and the second partition wall 22 are arranged on the same surface. By the partition wall 22, the passage sectional area on the downstream side of the collecting portion 15 is divided into two equal parts, that is, a relatively far side and a near side when viewed from the cylinder head 2. Of the passages in the collecting portion 15 that are divided into two equal parts, the side far from the cylinder head 2 is the first exhaust passage 24, and the near side is the collecting exhaust passage 27.

In the engine 1 according to the present embodiment described above, since the second exhaust passage 25 and the third exhaust passage 26 merge immediately before the entrance of the catalyst device 31, there is no partition immediately before the entrance of the catalyst device 31. The design flexibility of the exhaust manifold 11 is increased, and the exhaust manifold 11 can be made more compact than the first embodiment.

The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

For example, in the first embodiment, the exhaust discharged from the three exhaust ports of the independent exhaust port 5A, the collective exhaust port 6 and the independent exhaust port 5D is independently led to the inlet of the catalyst device 31, but the catalyst device You may make it guide to just before the entrance of 31.

This application claims priority based on Japanese Patent Application No. 2013-117066 filed with the Japan Patent Office on June 3, 2013, the entire contents of which are hereby incorporated by reference.

Claims

Among the exhaust ports that open to the four cylinders, respectively, there are a collective exhaust port in which two exhaust ports that are not in the ignition order are gathered inside, and the remaining two independent independent exhaust ports, A cylinder head in which three exhaust ports of the collective exhaust port and the two independent exhaust ports are opened on a side surface;
A catalytic device for purifying harmful components in the exhaust;
An exhaust manifold for connecting the three exhaust ports opened to the side surface of the cylinder head and the catalyst device;
An engine comprising
The exhaust manifold is
In order to guide the exhaust discharged from the three exhaust ports to the catalyst device, respectively, three exhaust passages partitioned by partition walls formed in the exhaust manifold are provided.
engine.
The exhaust passage in the exhaust manifold through which the exhaust discharged from the collective exhaust port flows is disposed on a relatively far side when viewed from the cylinder head,
The two exhaust passages in the exhaust manifold through which the exhaust discharged from the independent exhaust port flows are disposed on a relatively close side when viewed from the cylinder head.
The engine according to claim 1.
Exhaust in the exhaust manifold through which the exhaust discharged from the collective exhaust port flows when the cross-sectional area of each of the two exhaust passages in the exhaust manifold through which the exhaust discharged from the independent exhaust port flows is 1. The cross-sectional area of the passage is 2,
The engine according to claim 1 or 2.
The three exhaust passages guide the exhaust discharged from the three exhaust ports independently to the inlet of the catalyst device,
The engine according to any one of claims 1 to 3.
The two exhaust passages in the exhaust manifold through which the exhaust discharged from the independent exhaust port flows joins immediately before the inlet of the catalyst device;
The engine according to any one of claims 1 to 3.
The exhaust passage in the exhaust manifold through which the exhaust discharged from the collective exhaust port flows is disposed on a relatively close side when viewed from the cylinder head,
The two exhaust passages in the exhaust manifold through which the exhaust discharged from the independent exhaust port flows are disposed on a relatively far side when viewed from the cylinder head.
The engine according to claim 1.