CN108952989B

CN108952989B - Cylinder head of internal combustion engine

Info

Publication number: CN108952989B
Application number: CN201810510689.0A
Authority: CN
Inventors: 金原隆一
Original assignee: Suzuki Motor Corp
Current assignee: Suzuki Motor Corp
Priority date: 2017-05-26
Filing date: 2018-05-24
Publication date: 2021-04-20
Anticipated expiration: 2038-05-24
Also published as: DE102018207348A1; JP6930220B2; JP2018200017A; FR3066786A1; FR3066786B1; CN108952989A

Abstract

Provided is a cylinder head of an internal combustion engine, which can realize the miniaturization and the weight reduction of the cylinder head and reduce the ventilation resistance of an exhaust passage formed in the cylinder head. According to the cylinder head (3), the 1 st exhaust passages (9A), (10A), (11A) and the 2 nd exhaust passages (9B), (10B), (11B) are formed so as to overlap in the axial direction (O) of the 1 st cylinder (2A), the center cylinder (2B) and the 3 rd cylinder (2C) in the upstream portion of the 1 st collecting passage (12), (13), (14) and the cross section of each exhaust passage is changed from 2 circular cross sections to 1 longitudinal cross section, and the downstream portion of the 1 st collecting passage (12), (13), (14) communicating with the 2 nd collecting passage 15 is formed into a longitudinal cross section.

Description

Cylinder head of internal combustion engine

Technical Field

The present invention relates to a cylinder head of an internal combustion engine mounted on a vehicle.

Background

A cylinder head structure of a multi-cylinder engine is known in which exhaust ports extending from combustion chambers are collected in a cylinder head (see patent document 1). In this cylinder head structure, a pair of exhaust ports extending from a combustion chamber are collected into 1 exhaust port on a plane orthogonal to a cylinder axis, and then the exhaust ports communicating with all cylinders are collected in a collection portion.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2001-115893

Disclosure of Invention

Problems to be solved by the invention

In the cylinder head structure of the internal combustion engine, a pair of branch ports communicating with the combustion chamber are arranged side by side on a single plane and collected as 1 exhaust port, and exhaust ports corresponding to the respective cylinders are arranged side by side on a single plane and collected at the collection portion. Therefore, the cross section of the exhaust port from the combustion chamber to the most downstream collecting portion largely changes, and the flow resistance of the exhaust gas flowing through the exhaust port becomes large with the change in the cross section.

Further, when the exhaust ports are viewed from the cylinder axial direction, the width of the exhaust port provided for each cylinder is larger than the height of the exhaust port, and therefore, the width of an exhaust port collecting portion (hereinafter referred to as a collecting port) where the adjacent exhaust ports on the upstream side of the collecting portion are collected becomes large.

Therefore, the exhaust gas flowing from the exhaust port of each cylinder to the collecting port is merged early, and the exhaust gas of each cylinder is likely to interfere with each other, and the ventilation resistance may further increase, and the exhaust gas may not be smoothly discharged.

In order to solve the above problem, it is necessary to dispose a collecting portion, which is an outlet of the exhaust port that opens to the side surface of the cylinder head, at a position that is apart from the cylinder in the direction orthogonal to the arrangement direction of the cylinders, and to move the collecting position of the exhaust ports to the downstream side. Thus, the cylinder head becomes large and heavy.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a cylinder head of an internal combustion engine, which can reduce the size and weight of the cylinder head and can reduce the air flow resistance of an exhaust passage formed in the cylinder head.

Means for solving the problems

The present invention is a cylinder head provided at an upper portion of a cylinder block of an internal combustion engine having a plurality of cylinders arranged in a row, the cylinder head having an exhaust passage formed therein for discharging exhaust gas from the plurality of cylinders, the cylinder head being characterized in that the exhaust passage includes: a 1 st exhaust passage and a 2 nd exhaust passage communicating with each of the cylinders; a 1 st collective passage provided downstream of the 1 st exhaust passage and the 2 nd exhaust passage, the 1 st exhaust passage and the 2 nd exhaust passage being collected for each of the cylinders; a 2 nd collecting passage provided downstream of the 1 st collecting passage and collecting the 1 st collecting passage; and an exhaust gas outlet connected to the 2 nd collecting passage and discharging exhaust gas from the cylinder head to the outside, wherein the 1 st exhaust passage and the 2 nd exhaust passage overlap each other in an axial direction of the cylinder in an upstream portion of the 1 st collecting passage, a cross section of each exhaust passage is changed from 2 circular cross sections to 1 longitudinal cross section, and a downstream portion of the 1 st collecting passage communicating with the 2 nd collecting passage is formed to have a longitudinal cross section.

Effects of the invention

As described above, according to the present invention, the cylinder head can be reduced in size and weight, and the ventilation resistance of the exhaust passage formed inside the cylinder head can be reduced.

Drawings

Fig. 1 is a left side view of a cylinder head of an internal combustion engine according to an embodiment of the present invention.

Fig. 2 is a sectional view of a cylinder head showing an exhaust passage formed inside the cylinder head of an internal combustion engine, and a cylinder and a piston formed inside the cylinder according to an embodiment of the present invention.

Fig. 3 is a sectional view taken in the direction III-III of fig. 2.

Fig. 4 is a perspective view of an exhaust passage of a cylinder head of an internal combustion engine according to an embodiment of the present invention.

Fig. 5 is an enlarged cross-sectional view of the 2 nd collecting passage of the cylinder head of the internal combustion engine and its periphery according to the embodiment of the present invention.

Fig. 6 is a sectional view taken along direction VI-VI of fig. 5.

Fig. 7 is a plan view of an exhaust passage for the 1 st cylinder of the cylinder head of the internal combustion engine according to the embodiment of the present invention.

Fig. 8 is a sectional view taken along line VIII-VIII of fig. 7.

Fig. 9 is a view in section from direction IX-IX of fig. 7.

Fig. 10 is a cross-sectional view taken along the X-X direction of fig. 7.

Fig. 11 is a cross-sectional view taken in the direction XI-XI of fig. 7.

Description of the reference numerals

1.. an engine, 2a.. 1 st cylinder (cylinder), 2b.. 2 nd cylinder (cylinder, center cylinder), 2c.. 3 rd cylinder, 3.. cylinder head, 8.. exhaust passage, 9A, 10A, 11a.. 1 st exhaust passage, 9B, 10B, 11b.. 2 nd exhaust passage, 12, 13, 14.. 1 st collective passage, 15.. 2 nd collective passage, 15a.. exhaust gas outlet.

Detailed Description

A cylinder head of an internal combustion engine according to an embodiment of the present invention is provided at an upper portion of a cylinder block of the internal combustion engine having a plurality of cylinders arranged in a row, and an exhaust passage for discharging exhaust gas from the plurality of cylinders is formed in the cylinder head, wherein the exhaust passage includes: a 1 st exhaust passage and a 2 nd exhaust passage communicating with each cylinder; a 1 st collective passage provided downstream of the 1 st exhaust passage and the 2 nd exhaust passage, the 1 st exhaust passage and the 2 nd exhaust passage being collected for each cylinder; a 2 nd collecting passage provided downstream of the 1 st collecting passage and collecting the 1 st collecting passage; and an exhaust gas outlet which is connected to the 2 nd collecting passage and discharges exhaust gas from the cylinder head to the outside, the 1 st exhaust passage and the 2 nd exhaust passage are formed to overlap in the axial direction of the cylinder in an upstream portion of the 1 st collecting passage and each exhaust passage is changed in cross section from 2 circular cross sections to 1 longitudinal cross section, and a downstream portion of the 1 st collecting passage communicating with the 2 nd collecting passage is formed in a longitudinal cross section.

Therefore, the cylinder head can be reduced in size and weight, and the ventilation resistance of the exhaust passage formed inside the cylinder head can be reduced.

[ examples ] A method for producing a compound

The cylinder head of an internal combustion engine according to an embodiment of the present invention will be described below with reference to the drawings.

Fig. 1 to 11 are diagrams showing a cylinder head of an internal combustion engine according to an embodiment of the present invention. In fig. 1 to 11, regarding the vertical, front, rear, and left and right directions, when the 1 st cylinder side described later is the front and the 3 rd cylinder side is the rear in the direction along the bank of the engine, the width direction orthogonal to the bank of the engine is the left and right direction, and the height direction of the engine is the vertical direction.

First, the configuration is explained.

In fig. 1, an engine 1 includes a cylinder block 2 and a cylinder head 3 provided at an upper portion of the cylinder block 2.

In fig. 2, a plurality of 1 st, 2 nd, and 3

rd cylinders

2A, 2B, and 2C are provided in a cylinder block 2, and the 1 st, 2 nd, and 3

rd cylinders

2A, 2B, and 2C are arranged in a row. The engine 1 of the embodiment is a 3-cylinder engine.

The 1 st cylinder 2A, the 2 nd cylinder 2B, and the 3 rd cylinder 2C of the embodiment constitute the cylinders of the invention. The number of cylinders of the engine 1 of the embodiment is not limited to 3 cylinders.

Pistons 4 are respectively housed in the 1 st cylinder 2A, the 2 nd cylinder 2B, and the 3 rd cylinder 2C, and the pistons 4 reciprocate in the vertical direction with respect to the 1 st cylinder 2A, the 2 nd cylinder 2B, and the 3 rd cylinder 2C.

The piston 4 is coupled to a crankshaft, not shown, via a connecting rod, not shown, and the reciprocating motion of the piston 4 is converted into rotational motion of the crankshaft via the connecting rod. A combustion chamber 5 is formed between the top of the piston 4, the inner walls of the 1 st cylinder 2A, the 2 nd cylinder 2B, and the 3 rd cylinder 2C, and the bottom of the cylinder head 3.

In fig. 3, a plurality of intake passages 6 are formed in the cylinder head 3. The intake passage 6 has intake ports 7, a pair of intake ports 7 are provided for each of the 1 st cylinder 2A, the 2 nd cylinder 2B, and the 3 rd cylinder 2C, and the pair of intake ports 7 communicate with the 1 st cylinder 2A, the 2 nd cylinder 2B, and the 3 rd cylinder 2C, respectively.

The intake passage 6 communicates with an intake passage of an intake pipe, not shown, via an intake manifold, not shown. The intake pipe introduces intake air into the intake manifold, and the intake air introduced into the intake manifold is introduced into each of the cylinders 2A to 2C through the intake port 7. Fuel is introduced into each of the cylinders 2A to 2C together with intake air, and a mixture of intake air and fuel is combusted in the combustion chamber 5.

An exhaust passage 8 is formed in the cylinder head 3. In fig. 3 and 4, the exhaust passage 8 includes the 1

st exhaust passages

9A, 10A, and 11A and the 2

nd exhaust passages

9B, 10B, and 11B. The pair of 1 st and 2

nd exhaust passages

9A and 9B communicate with the 1 st cylinder 2A, the pair of 1 st and 2

nd exhaust passages

10A and 10B communicate with the 2 nd cylinder 2B, and the pair of 1 st and 2

nd exhaust passages

11A and 11B communicate with the 3 rd cylinder 2C.

The exhaust passage 8 has a 1 st

collective passage

12, 13, 14 and a 2 nd collective passage 15.

The 1 st collecting passage 12 is provided downstream of the 1 st exhaust passage 9A and the 2 nd exhaust passage 9B, and collects the 1 st exhaust passage 9A and the 2 nd exhaust passage 9B. The upstream and downstream indicate upstream and downstream in the flow direction of the exhaust gas.

The 1 st collecting passage 13 is provided downstream of the 1 st exhaust passage 10A and the 2 nd exhaust passage 10B, and collects the 1 st exhaust passage 10A and the 2 nd exhaust passage 10B. The 1 st collecting passage 14 is provided downstream of the 1 st exhaust passage 11A and the 2 nd exhaust passage 11B, and collects the 1 st exhaust passage 11A and the 2 nd exhaust passage 11B.

In this way, the 1 st collecting passage 12 to 14 collects the 1

st exhaust passages

9A, 10A, 11A and the 2

nd exhaust passages

9B, 10B, 11B for each of the 1 st cylinder 2A to the 3 rd cylinder 2C.

In fig. 3, the 1 st collecting passage 12 to 14 are adjacent to each other with

partition walls

16 and 17 interposed therebetween, and the

partition walls

16 and 17 extend from the

respective cylinders

2A, 2B, and 2C sides to the vicinity of the 2 nd collecting passage 15.

In fig. 5, the 2 nd collecting passage 15 is provided downstream of the 1 st collecting passages 12 to 14, and the 1 st collecting passages 12 to 14 corresponding to all the cylinders 2A to 2C are collected. An exhaust gas outlet 15A is provided downstream of the 2 nd collecting passage 15, and the exhaust gas outlet 15A opens on the left side surface of the cylinder head 3.

In fig. 1, a flange portion 3F surrounding the outer periphery of the exhaust gas outlet 15A is formed on the left side surface of the cylinder head 3, and a plurality of screw holes 3F are formed in the flange portion 3F. A flange portion of an exhaust pipe, not shown, is joined to the flange portion 3F, and in a state where the flange portion of the exhaust pipe is joined to the flange portion 3F, a screw, not shown, is attached to the screw hole 3F, thereby connecting the exhaust pipe to the cylinder head 3.

The exhaust gas outlet 15A communicates with an exhaust passage of an exhaust pipe, and exhaust gas burned in the combustion chamber 5 is collected from the 1 st cylinder 2A to the 1 st collecting passage 12 through the 1 st exhaust passage 9A and the 2 nd exhaust passage 9B.

The exhaust gas burned in the combustion chamber 5 is collected from the 2 nd cylinder 2B to the 1 st collecting passage 13 through the 1 st exhaust passage 10A and the 2 nd exhaust passage 10B. The exhaust gas burned in the combustion chamber 5 is collected from the 3 rd cylinder 2C to the 1 st collecting passage 14 through the 1 st exhaust passage 11A and the 2 nd exhaust passage 11B.

The exhaust gas collected in the 1 st collecting passage 12 to 14 is collected in the 2 nd collecting passage 15 from the 1 st collecting passage 12 to 14, and then discharged from the exhaust gas outlet 15A to the exhaust pipe and discharged from the cylinder head 3.

The 1

st exhaust passages

9A, 10A, 11A and the 2

nd exhaust passages

9B, 10B, 11B are formed to overlap in the axial direction O of the cylinder in the upstream portion of the 1 st

collective passage

12, 13, 14 and each exhaust passage is changed in cross section from 2 circular cross sections to 1 oblong longitudinal cross section. The axial direction O of the cylinders is the axial direction O of each of the cylinders 2A to 2C.

Fig. 6 shows a state in which the 1 st exhaust passage 11A and the 2 nd exhaust passage 11B overlap in the axial direction of the 3 rd cylinder 2C in the upstream portion of the 1 st collecting passage 14. In the cylinder head 3 of the present embodiment, the axial direction O (see fig. 2) of the cylinder is the same direction as the vertical direction (vertical direction) of the engine 1.

Fig. 7 to 10 show a cross section from the upstream side of the 1 st exhaust passage 9A and the 2 nd exhaust passage 9B to the 1 st collective passage 12. As shown in fig. 8, the 1 st exhaust passage 9A and the 2 nd exhaust passage 9B are formed with 2 circular cross sections on the upstream side thereof, and as shown in fig. 9, the 2 circular cross sections gradually overlap as going from upstream to downstream.

Further downstream, as shown in fig. 10, the 1 st exhaust passage 9A and the 2 nd exhaust passage 9B overlap in the axial direction O of the 1 st cylinder 2A in the upstream portion of the 1 st collecting passage 12 so as to have 1 longitudinal cross section.

The downstream portions of the 1 st collecting passages 12 to 14 communicating with the 2 nd collecting passage 15 are formed in a longitudinal cross section. For example, as shown in fig. 11, the downstream side of the 1 st collecting passage 12 communicating with the 2 nd collecting passage 15 is formed in an oblong longitudinal cross section in the up-down direction. Although not shown, the downstream side of the 1

st collecting passage

13, 14 communicating with the 2 nd collecting passage 15 is also formed to have a vertically long cross section in the same manner. Further, the oblong is an oblong that is long in the up-down direction.

In fig. 10 and 11, the lateral width W1 of the 1 st collecting passage 12 is formed to be the same as the lateral width W2 of the downstream portion of the 2 nd exhaust passage 9B when viewed from the axial direction O of the 1 st cylinder 2A.

Although not shown, the lateral width W1 of the 1

st collecting passage

13, 14 is also formed to be the same as the lateral width W2 of the downstream portion of the 2

nd exhaust passage

10B, 11B when viewed in the axial direction O of the 2 nd cylinder 2B and the 3 rd cylinder 2C.

The lateral width W1 of the 1 st collecting passage 12 may be formed to be the same as the lateral width W2 of the 1

st exhaust passages

9A, 10A, 11A when viewed from the axial direction O of the cylinder. It is also possible to form the lateral width W1 of the 1 st collective passage 12 to be the same as the lateral width W2 common to the 1 st and 2

nd exhaust passages

9A, 9B, the lateral width W2 common to the 1 st and 2

nd exhaust passages

10A, 10B, and the lateral width W2 common to the 1 st and 2

nd exhaust passages

11A, 11B.

In fig. 3, a 2 nd exhaust passage 10B communicating with a 2 nd cylinder 2B (hereinafter, this cylinder is referred to as a center cylinder 2B) provided at a center portion of the cylinder head 3 in the cylinder arrangement direction L extends from the center cylinder 2B in a direction orthogonal to the cylinder arrangement direction L. The direction L in which the cylinders are arranged is a direction in which the cylinders 2A to 2C are arranged, and is the same direction as the front-rear direction of the engine 1.

The 1 st exhaust passage 10A is curved from the center cylinder 2B toward the 2 nd exhaust passage 10B and is collected in the 2 nd exhaust passage 10B, and the exhaust gas outlet 15A is provided at a position offset toward the 2 nd exhaust passage 10B side with respect to the center axis of the center cylinder 2B (the same axis as the axial direction O of the center cylinder 2B).

Further, the arrangement of the 1 st exhaust passage 10A and the 2 nd exhaust passage 10B may be reversed. That is, the 1 st exhaust passage 10A may be extended in a direction orthogonal to the direction L in which the cylinders are arranged, and the 2 nd exhaust passage 10B may be bent from the center cylinder 2B toward the 1 st exhaust passage 10A and collected in the 1 st exhaust passage 10A.

In this way, according to the cylinder head 3 of the present embodiment, the 1

st exhaust passages

9A, 10A, 11A and the 2

nd exhaust passages

9B, 10B, 11B are formed so as to overlap in the axial direction O of the cylinder in the upstream portion of the 1 st

collective passage

12, 13, 14 and the cross section of each exhaust passage changes from 2 circular cross sections to 1 longitudinal cross section.

Therefore, it is possible to prevent the cross-sectional area of the exhaust passage 8 from largely changing before and after the 1

st exhaust passages

9A, 10A, and 11A and the 2

nd exhaust passages

9B, 10B, and 11B are collected by the 1

st collecting passages

12, 13, and 14. Therefore, the ventilation resistance of the exhaust passage 8 can be reduced.

Further, since the downstream portions of the 1

st collecting passages

12, 13, 14 communicating with the 2 nd collecting passage 15 are formed to have a longitudinal cross section, the downstream portions of the 1

st collecting passages

12, 13, 14 can communicate with the 2 nd collecting passage 15 in a longitudinal cross section.

Accordingly, the

partition walls

16 and 17 formed between the 1

st collecting passages

12, 13, and 14 adjacent to each other can be extended to the vicinity of the 2 nd collecting passage 15. Therefore, the exhaust gas discharged from the 1 st cylinder 2A, the center cylinder 2B, and the 3 rd cylinder 2C to the 1

st exhaust passages

9A, 10A, 11A and the 2

nd exhaust passages

9B, 10B, 11B can be guided to the 2 nd collecting passage 15 without interference. Therefore, the ventilation resistance of the exhaust passage 8 can be reduced more effectively.

Further, by forming the 1

st collecting passage

12, 13, 14 to have a vertically long cross section, the 1

st collecting passage

12, 13, 14 can be freely bent in a direction horizontally intersecting the axial direction O of the cylinder.

Accordingly, the 1

st collecting passage

12, 13, 14 can be bent in the direction horizontally intersecting the axial direction O of the cylinder and can communicate with the 2 nd collecting passage 15, the downstream ends thereof can be brought closer to the

cylinders

2A, 2B, 2C side in the direction horizontally intersecting the axial direction O of the cylinder, and the exhaust gas outlet 15A can be brought closer to the

cylinders

2A, 2B, 2C side. As a result, the dimension of the cylinder head 3 in the vehicle width direction (the lateral direction of the vehicle) can be reduced, and the cylinder head 3 can be made smaller and lighter.

In addition, according to the cylinder head 3 of the present embodiment, the 1 st longitudinal cross section formed by overlapping the downstream portions of the 1

st exhaust passages

9A, 10A, 11A and the 2

nd exhaust passages

9B, 10B, 11B in the axial direction of the cylinder and the 1 st longitudinal cross section of the 1

st collecting passage

12, 13, 14 are formed in long circles in the vertical direction.

Therefore, when the 1

st collecting passages

12, 13, 14 are collected in the 2 nd collecting passage 15, the intervals in the lateral direction (arrangement direction) of the 1

st collecting passages

12, 13, 14 can be further shortened as compared with the case where the 1

st collecting passages

12, 13, 14 are formed in a circular shape in cross section, and the cylinder head 3 can be more effectively reduced in size and weight.

In addition, according to the cylinder head 3 of the present embodiment, the lateral width W1 of the 1

st collecting passage

12, 13, 14 is formed to be the same width as the lateral width W2 of the downstream portion of the 1

st exhaust passage

9A, 10A, 11A or the downstream portion of the 2

nd exhaust passage

9B, 10B, 11B when viewed from the axial direction O of the cylinder.

Therefore, the 1

st exhaust passages

9A, 10A, and 11A and the 2

nd exhaust passages

9B, 10B, and 11B can be more effectively prevented from largely changing in cross-sectional area before and after being collected by the 1

st collecting passages

12, 13, and 14, and the ventilation resistance of the exhaust passage 8 can be more effectively reduced.

In addition, according to the cylinder head 3 of the present embodiment, the 2 nd exhaust passage 9B communicating with the center cylinder 2B provided at the center portion of the cylinder head 3 in the arrangement direction L of the cylinders extends from the center cylinder 2B in the direction orthogonal to the arrangement direction L of the cylinders.

The 1 st exhaust passage 9A is curved from the center cylinder 2B toward the 2 nd exhaust passage 9B and is collected in the 2 nd exhaust passage 9B, and the exhaust gas outlet 15A is provided at a position offset toward the 2 nd exhaust passage 9B side with respect to the center axis O (the same as the axial direction O) of the center cylinder 2B.

Accordingly, the 1 st exhaust passage 10A and the 2 nd exhaust passage 10B can be collected in the vicinity of the center cylinder 2B, and the exhaust gas outlet 15A can be brought closer to the center cylinder 2B side accordingly. As a result, the cylinder head 3 can be more effectively reduced in size and weight.

Although the present embodiment of the invention has been disclosed, it is apparent that modifications can be made by those skilled in the art without departing from the scope of the invention. All such modifications and equivalents are intended to be included within the scope of the appended claims.

Claims

1. A cylinder head of an internal combustion engine, which is provided at an upper portion of a cylinder block of the internal combustion engine having a plurality of cylinders arranged in a row, the cylinder head being formed with an exhaust passage for discharging exhaust gas from the plurality of cylinders,

the exhaust passage includes:

a 1 st exhaust passage and a 2 nd exhaust passage communicating with each of the cylinders;

a 1 st collective passage provided downstream of the 1 st exhaust passage and the 2 nd exhaust passage, the 1 st exhaust passage and the 2 nd exhaust passage being collected for each of the cylinders;

a 2 nd collecting passage provided downstream of the 1 st collecting passage and collecting the 1 st collecting passage; and

an exhaust gas outlet connected to the 2 nd collecting passage and discharging exhaust gas from the cylinder head to the outside,

the 1 st exhaust passage and the 2 nd exhaust passage are formed to overlap in the axial direction of the cylinder in an upstream portion of the 1 st collective passage and a cross section of each exhaust passage changes from 2 circular cross sections to 1 longitudinal cross section,

the downstream portion of the 1 st collecting passage communicating with the 2 nd collecting passage is formed to have a vertically long cross section,

the longitudinal cross section of the upstream portion of the 1 st collection passage and the longitudinal cross section of the downstream portion of the 1 st collection passage, in which the 1 st exhaust passage and the 2 nd exhaust passage overlap in the axial direction of the cylinder, are oblong in the axial direction of the cylinder.

2. The cylinder head of an internal combustion engine according to claim 1,

the lateral width of the 1 st collecting passage is formed to be the same as the lateral width of the downstream portion of the 1 st exhaust passage or the lateral width of the downstream portion of the 2 nd exhaust passage when viewed from the axial direction of the cylinder.

3. The cylinder head of the internal combustion engine according to claim 1 or 2,

in the case where a cylinder provided at the center of the cylinder head in the direction of arrangement of the cylinders is a center cylinder, one of the exhaust passages 1 and 2 communicating with the center cylinder extends from the center cylinder in a direction orthogonal to the direction of arrangement of the cylinders, and the other exhaust passage curves from the center cylinder toward the one exhaust passage and merges into the one exhaust passage,

the exhaust gas outlet is provided at a position offset toward the one exhaust passage with respect to the center axis of the center cylinder.