JP6435693B2 - Cylinder head of internal combustion engine - Google Patents

Description

  The present invention relates to a cylinder head of an internal combustion engine, and more particularly to a cylinder head of an internal combustion engine in which a plurality of exhaust ports communicating with a combustion chamber and an exhaust collecting portion that collects a plurality of exhaust ports are integrally formed.

An internal combustion engine mounted on a vehicle such as an automobile includes a cylinder head. As a conventional cylinder head of this type, there is known one in which a plurality of exhaust ports communicating with a combustion chamber and an exhaust collecting portion for collecting a plurality of exhaust ports are integrally formed (for example, Patent Document 1). reference).
This cylinder head is provided with a plurality of exhaust ports along the cylinder row direction, and each exhaust port has an inner diameter that gradually increases from the combustion chamber toward the exhaust collecting portion.

  Further, the exhaust port formed at the center in the cylinder row direction faces the exhaust collecting portion in a direction orthogonal to the cylinder row direction, and the passage length of the exhaust port formed at the center in the cylinder row direction is The passage length is shorter than the passage length of the exhaust port formed on both sides in the cylinder row direction.

  Each exhaust port has a curved bottom surface curved upward from the combustion chamber and an inclined bottom surface inclined obliquely upward from the curved bottom surface, and exhaust gas discharged from the combustion chamber is directed upward to the exhaust collecting portion. Collected.

JP 2000-161132 A

  In such a cylinder head of a conventional internal combustion engine, the passage length of the exhaust port formed on both sides in the cylinder row direction is longer than the passage length of the exhaust port formed in the center in the cylinder row direction. Therefore, the passage area of the exhaust port does not increase rapidly. Thereby, the exhaust gas discharged from the combustion chamber to the exhaust port is easily rectified in the process of reaching the exhaust collecting portion.

  On the other hand, the passage length of the exhaust port formed in the center in the cylinder row direction is shorter than the passage length of the exhaust port formed on both sides in the cylinder row direction. The passage area of the exhaust port increases rapidly.

  As a result, the exhaust gas exhausted to the exhaust port is difficult to be rectified in the process of reaching the exhaust collecting portion, and the exhaust gas may become turbulent on the bottom surface of the exhaust port or stagnation may occur. For this reason, the back pressure of the exhaust gas discharged from the combustion chamber to the exhaust port becomes high, and the exhaust gas discharge performance may be deteriorated.

  The present invention has been made paying attention to the above problems, and can prevent the back pressure of the exhaust gas discharged from the combustion chamber to the straight exhaust port from becoming high, and the exhaust gas discharge performance is improved. It is an object of the present invention to provide a cylinder head of an internal combustion engine that can prevent a decrease.

According to a first aspect of the present invention, a cylinder head is provided at an upper portion of a cylinder block of an internal combustion engine having cylinders, and has a plurality of combustion chambers along a cylinder row direction and a plurality of exhaust ports communicating with the combustion chambers. When the exhaust port is viewed from above, the plurality of exhaust ports are formed integrally with the cylinder head and extend in a direction perpendicular to the cylinder row direction, and then the cylinder row direction. A curved exhaust port that is curved in a straight line with the cylinder head, and a passage length that is shorter than a passage length of the curved exhaust port, in a direction orthogonal to the cylinder row direction. A linear exhaust port that extends, and an exhaust collecting portion that is formed integrally with the cylinder head and collects the curved exhaust port and a downstream portion of the linear exhaust port. And the straight exhaust port communicates with the combustion chamber, has a curved bottom surface that curves upward from the combustion chamber, and an inclined bottom surface that slopes obliquely upward from the curved bottom surface. The inner diameter gradually increases toward the portion, the bottom surface of the exhaust collecting portion is used as a reference surface, and the reference surface is provided with a virtual extension surface extending toward the upstream end side of the linear exhaust port. A bulging portion bulging upward from the virtual extension surface is formed on the bottom surface of the exhaust port, and the bulging portion is the virtual extension surface of the curved bottom surface in a direction orthogonal to the cylinder row direction. It is formed over the region to contact the bottom surface portion and the exhaust collector which is located above the, plane parallel to the straight exhaust port and the cylinder row direction parallel to the height direction of the cylinder head Cut off In cross section, and a what is formed to be a flat surface the bottom surface of the straight exhaust port constituted by the bulging portion over the entire area of the cylinder row direction.

  Thus, according to the first aspect described above, in the linear exhaust port that is formed with a passage length shorter than the passage length of the curved exhaust port and whose inner diameter gradually increases from the combustion chamber toward the exhaust collecting portion. When a virtual extension surface is provided with the bottom surface of the exhaust collecting portion as a reference surface and the reference surface extending toward the upstream end of the linear exhaust port, the bottom surface of the linear exhaust port swells above the virtual extension surface. A bulging portion is formed.

  Thereby, it is possible to prevent the passage area from the upstream end portion of the linear exhaust port to the exhaust collecting portion from rapidly expanding. For this reason, even when the exhaust gas flowing while coming into contact with the curved bottom surface of the straight exhaust port from the combustion chamber is peeled off at the curved bottom surface, turbulence of the exhaust gas occurs at the bulging portion immediately after the peeling. And you can eliminate the grudge.

  Therefore, it is possible to prevent the turbulent flow of the exhaust gas from occurring on the inclined bottom surface of the straight exhaust port and to prevent the stagnation, and the exhaust gas can be rectified and flowed to the exhaust collecting portion. As a result, the back pressure of the exhaust gas can be prevented from increasing at the linear exhaust port, and the exhaust gas exhaust performance can be prevented from deteriorating.

FIG. 1 is a view showing an embodiment of a cylinder head of an internal combustion engine according to the present invention, and is a front view of the engine. FIG. 2 is a view showing an embodiment of the cylinder head of the internal combustion engine of the present invention, and is a top view of the engine. FIG. 3 is a view showing an embodiment of the cylinder head of the internal combustion engine of the present invention, and is a cross-sectional view taken along the line III-III in FIG. 4 is a view showing an embodiment of a cylinder head of the internal combustion engine of the present invention, and is a cross-sectional view taken along the IV-IV direction of FIG. FIG. 5 is a view showing an embodiment of the cylinder head of the internal combustion engine of the present invention, and is a front view of the cylinder head. 6 is a view showing an embodiment of a cylinder head of the internal combustion engine of the present invention, and is a cross-sectional view taken along the line VI-VI in FIG. FIG. 7 is a view showing an embodiment of a cylinder head of the internal combustion engine of the present invention, and is a view showing a flow of exhaust gas in an exhaust port in which a bulging portion is not formed. FIG. 8 is a view showing an embodiment of a cylinder head of the internal combustion engine of the present invention, and is a view showing a flow of exhaust gas in an exhaust port in which a bulging portion is formed.

Embodiments of a cylinder head of an internal combustion engine according to the present invention will be described below with reference to the drawings.
FIGS. 1-8 is a figure which shows the cylinder head of the internal combustion engine of one Embodiment based on this invention.
First, the configuration will be described.
1 to 3, an engine 1 as an internal combustion engine mounted on a vehicle such as an automobile is provided with a cylinder block 2, a cylinder head 3 provided on an upper part of the cylinder block 2, and an upper part of the cylinder head 3. And a cylinder head cover 4 and an oil pan 5 attached to the lower part of the cylinder block 2 for storing oil.

  2, the cylinder block 2 is provided with a plurality of cylinders 6A to 6C along the vehicle width direction, and pistons (not shown) are accommodated in the cylinders 6A to 6C so as to be movable up and down.

  As shown in FIG. 4, combustion chambers 7 </ b> A to 7 </ b> C are formed at the bottom of the cylinder head 3 as indicated by broken lines, and the combustion chambers 7 </ b> A to 7 </ b> C are formed along the arrangement direction of the cylinders 6 </ b> A to 6 </ b> C. The cylinders 6A to 6C communicate with each other. Here, in FIG. 3, the combustion chamber 7B is formed at the bottom of the cylinder head 3, and the combustion chambers 7A and 7C are also formed at the bottom of the cylinder head 3 in the same shape as the combustion chamber 7B.

  In FIG. 2, an intake manifold 8 is connected to the rear portion of the cylinder head 3, and intake air is introduced into the intake manifold 8 from an intake pipe (not shown). In FIG. 4, a plurality of intake ports 9 are formed in the cylinder head 3, and intake air is introduced into the intake ports 9 through the intake manifold 8.

The intake port 9 communicates with the cylinders 6A to 6C through the combustion chambers 7A to 7C, respectively, and the air introduced into the intake port 9 is introduced into the cylinders 6A to 6C through the combustion chambers 7A to 7C.
A plurality of exhaust ports 10 are formed in the cylinder head 3. Each exhaust port 10 communicates with the cylinders 6A to 6C through the combustion chambers 7A to 7C, respectively.

  In FIG. 4, when the exhaust port 10 is viewed from above, the exhaust port 10 extends in a direction orthogonal to the arrangement direction of the cylinders 6A to 6C and then curves in the arrangement direction of the cylinders 6A to 6C. A straight exhaust port 13 having a passage length shorter than that of the curved exhaust ports 11 and 12 and extending in a direction orthogonal to the arrangement direction of the cylinders 6A to 6C; The exhaust ports 11 and 12 and the exhaust collecting portion 14 that collects the downstream portions of the linear exhaust ports 13 are configured. Here, the arrangement direction of the cylinders 6A to 6C corresponds to the cylinder row direction of the present invention.

The curved exhaust ports 11 and 12, the linear exhaust port 13 and the exhaust collecting portion 14 are formed integrally with the cylinder head 3. An opening 14 a is formed on the front surface of the cylinder head 3 (see FIG. 5), and the opening 14 a constitutes the downstream end of the curved exhaust port 11.
In FIG. 5, when the cylinder head 3 is viewed from a direction orthogonal to the arrangement direction of the combustion chambers 7 </ b> A to 7 </ b> C, the linear exhaust port 13 overlaps the opening 14 a from the combustion chamber 7 </ b> B to the exhaust collecting portion 14. It extends. For this reason, the total length of the linear exhaust port 13 is formed shorter than the total length of the curved exhaust ports 11 and 12.

  1 and 2, a turbocharger 15 is attached to the front surface of the cylinder head 3, and the inside of the turbocharger 15 communicates with the opening 14a. A catalytic converter 17 is connected to the turbocharger 15 via an exhaust pipe 16.

  In the engine 1 of the present embodiment, the exhaust gas discharged from the combustion chambers 7A to 7C is discharged to the exhaust collecting portion 14 through the curved exhaust ports 11 and 12 and the straight exhaust port 13 and is collected at the exhaust collecting portion 14. .

  A part of the exhaust gas collected at the exhaust collecting portion 14 is introduced into a turbine (not shown) of the turbocharger 15 to rotate the turbine. The remaining exhaust gas is introduced into the catalytic converter 17 through the exhaust pipe 16 and purified by the catalytic converter 17, and then discharged to the atmosphere through an exhaust pipe (not shown) connected to the downstream end of the catalytic converter 17.

  4 and 6, the straight exhaust port 13 communicates with the combustion chamber 7B, has a curved bottom surface 13a that curves upward from the combustion chamber 7B, and an inclined bottom surface 13b that slopes obliquely upward from the curved bottom surface 13a. The inner diameter of the exhaust port 13 gradually increases from the combustion chamber 7 </ b> B toward the exhaust collecting portion 14.

  In FIG. 4, the curved exhaust ports 11 and 12 communicate with the combustion chambers 7A and 7C, and are curved bottom surfaces 11a and 12a that are curved upward from the combustion chambers 7A and 7C, and are slanted obliquely upward from the curved bottom surfaces 11a and 12a. The curved exhaust ports 11 and 12 have bottom surfaces 11b and 12b, and the inner diameters of the curved exhaust ports 11 and 12 gradually increase from the combustion chambers 7A and 7C toward the exhaust collecting portion 14.

  In FIG. 6, in the straight exhaust port 13, when the bottom surface of the exhaust collecting portion 14 is a reference surface 18, and the reference surface 18 is provided with a virtual extension surface 19 extending toward the upstream end side of the straight exhaust port 13, A bulging portion 20 bulging above the virtual extension surface 19 is formed on the bottom surface of the linear exhaust port 13.

  The bulging portion 20 is formed in a region between the upper portion 20a that is a portion located above the virtual extension surface 19 in the curved bottom surface 13a and the bottom surface of the exhaust collecting portion 14. That is, the inclined surface 13 b of the present embodiment has the bulging portion 20. Here, in FIG. 6, a range where the bulging portion 20 is formed is indicated by reference numeral 20. Further, upstream and downstream mean upstream and downstream in the direction in which the exhaust gas flows.

  Further, in the cylinder head 3 of the present embodiment, the combustion chamber 7A formed at one end (right end) in the arrangement direction of the cylinders 6A to 6C shown in FIG. 4 constitutes one end side combustion chamber of the present invention, and the cylinder The combustion chamber 7C formed at the other end (left end) in the arrangement direction of 6A to 6C constitutes the other end side combustion chamber of the present invention. Further, the combustion chamber 7B formed between the combustion chamber 7A and the combustion chamber 7C constitutes the intermediate combustion chamber of the present invention.

  Thus, in the cylinder head 3 of the present embodiment, the bulging portion 20 is formed in the linear exhaust port 13 extending from the combustion chamber 7B formed between the combustion chambers 7A and 7C.

  3 and 6, water jackets 21 </ b> A to 21 </ b> C and 22 </ b> A to 22 </ b> C are formed on the lower side and the upper side of the curved exhaust ports 11 and 12 and the linear exhaust port 13, respectively. , 12 and the linear exhaust port 13 are cooled by the cooling water W flowing through the water jackets 21A to 21C and 22A to 22C.

In FIG. 3, a cooling water inlet 24 is formed on the joint surface 23 of the cylinder block 2 in the cylinder head 3.
The coolant introduction port 24 communicates with the water jackets 21A to 21C of the cylinder head 3 and the water jackets 25A to 25C formed in the cylinder block 2, and the coolant introduction port 24 is discharged from the water jackets 25A to 25C. Cooling water is allowed to flow into the water jackets 21A to 21C.

  The cooling water that has flowed into the water jackets 21A to 21C is introduced from the water jackets 21A to 21C into the water jackets 22A to 22C.

  The cooling water introduction port 24 opens below the bulging portion 20 so as to overlap in the height direction of the engine 1, and the cooling water flowing into the water jacket 21 </ b> B from the cooling water introduction port 24 passes through the bulging portion 20. Collide directly with the bottom.

  As shown in FIG. 2, when the cylinder head 3 is cut along a cross section perpendicular to the arrangement direction of the cylinders 6A to 6C and along the arrangement direction of the cylinders 6A to 6C, as shown in FIG. The height position T1 of the bottom surface of the linear exhaust port 13 in the height direction is formed at a position higher than the height position T2 of the bottom surfaces of the curved exhaust ports 11 and 12 in the height direction of the engine 1.

Next, the operation will be described.
In the cylinder head 3 of the present embodiment, when the exhaust port 10 is viewed from above, the exhaust port 10 extends in a direction orthogonal to the arrangement direction of the cylinders 6A to 6C and then extends in the arrangement direction of the cylinders 6A to 6C. Curved exhaust ports 11, 12 that are curved, and linear exhaust ports that are formed with a passage length shorter than the passage length of the curved exhaust ports 11, 12, and extend in a direction orthogonal to the arrangement direction of the cylinders 6A to 6C. 13 and the curved exhaust ports 11 and 12 and the exhaust collecting portion 14 that collects the downstream portions of the linear exhaust ports 13.

  Here, since the curved exhaust ports 11 and 12 having a long passage length do not rapidly expand the passage area, the exhaust gas discharged from the combustion chambers 7A and 7C to the curved exhaust ports 11 and 12 is It is easy to rectify in the process of reaching the exhaust collecting portion 14.

  On the other hand, the linear exhaust port 13 having a short passage length has a passage area that increases rapidly, so that the exhaust gas exhausted from the combustion chamber 7B to the linear exhaust port 13 reaches the exhaust collecting portion 14. It is difficult to be rectified in the process.

  For this reason, as shown in FIG. 7, the exhaust gas G1 flowing through the straight exhaust port 31 where the bulging portion 20 is not formed is turbulent as shown by the arrow A at the bottom surface of the straight exhaust port 31. Or itching may occur. As a result, the back pressure of the exhaust gas discharged from the combustion chamber to the linear exhaust port 31 becomes high, and the exhaust gas discharge performance may be deteriorated.

  On the other hand, according to the cylinder head 3 of this embodiment, the passage length is shorter than the passage length of the curved exhaust ports 11 and 12, and the inner diameter gradually increases from the combustion chamber 7B toward the exhaust collecting portion 14. In the expanding straight exhaust port 13, when the bottom surface of the exhaust collecting portion 14 is used as a reference surface 18 and the reference surface 18 is provided with a virtual extension surface 19 extending toward the upstream end side of the straight exhaust port 13, the straight exhaust port 13 is linear. A bulging portion 20 bulging upward from the virtual extension surface 19 was formed on the bottom surface of the exhaust port 13.

  Thereby, it is possible to prevent the passage area from the upstream end portion of the linear exhaust port 13 to the exhaust collecting portion 14 from rapidly expanding. For this reason, even if the exhaust gas flowing while coming into contact with the curved bottom surface 13a of the linear exhaust port 13 from the combustion chamber 7B is peeled off at the curved bottom surface 13a, the exhaust gas turbulence at the bulging portion 20 immediately after being peeled off. It is possible to eliminate the occurrence of flow and envy.

Therefore, it is possible to prevent the exhaust gas from being turbulent and stagnant at the inclined bottom surface 13b of the linear exhaust port 13, that is, the bulging portion 20, and to rectify and flow the exhaust gas to the exhaust collecting portion 14. it can. As a result, the back pressure of the exhaust gas can be prevented from increasing at the straight exhaust port 13, and the exhaust gas exhaust performance can be prevented from deteriorating.
FIG. 8 shows a state where the exhaust gas G2 flows smoothly by eliminating the turbulent flow of the exhaust gas and the stagnation of the swelled portion 20 of the linear exhaust port 13.

  Further, according to the cylinder head 3 of the present embodiment, the water jackets 21 </ b> A to 21 </ b> C into which the cooling water flows from the cylinder block 2 are formed below the curved exhaust ports 11 and 12 and the linear exhaust port 13.

  Accordingly, the volume of the water jackets 21A to 21C can be increased by the thickness of the bulging portion 20, and more cooling water can be circulated through the water jackets 21A to 21C. For this reason, the cooling property of the linear exhaust port 13 can be improved.

  Accordingly, it is possible to prevent the exhaust gas temperature from excessively rising at the exhaust collecting portion 14. In addition, since the cylinder head 3 can be cooled, the cylinder head 3 can be prevented from deteriorating and the life of the cylinder head 3 can be extended.

  Further, a cooling water inlet 24 that flows in from the cylinder block 2 is formed on the joint surface 23 of the cylinder block 2 in the cylinder head 3, and the bulging portion is formed so that the cooling water inlet 24 overlaps in the height direction of the engine 1. 20 was opened below.

  Thereby, the low-temperature cooling water flowing into the cylinder head 3 from the cylinder block 2 through the cooling water inlet 24 can be directly collided with the lower portion of the bulging portion 20. For this reason, the cooling property of the linear exhaust port 13 can be improved more effectively.

  Further, according to the cylinder head 3 of the present embodiment, the bulging portion 20 is located in the region between the upper portion 20a positioned above the virtual extension surface 19 in the curved bottom surface 13a and the bottom surface of the exhaust collecting portion 14. Formed. Thereby, it is possible to prevent the passage area of the straight exhaust port 13 between the curved bottom surface 13a and the exhaust collecting portion 14 from rapidly expanding.

  For this reason, it is possible to prevent the turbulent flow of the exhaust gas from occurring in the bulging portion 20 of the linear exhaust port 13 or to stagnate it, and to rectify and flow the exhaust gas to the exhaust collecting portion 14. In addition to this, the volume of the water jacket 21B can be increased more effectively, and more cooling water can be circulated through the water jacket 21B. For this reason, the cooling property of the linear exhaust port 13 can be improved more effectively.

  Further, according to the cylinder head 3 of the present embodiment, the combustion chamber 7A formed at one end (right end) of the cylinders 6A to 6C and the other end (left end) of the cylinders 6A to 6C in the arrangement direction. The bulging part 20 was formed in the linear exhaust port 13 extended from the combustion chamber 7B formed between the combustion chambers 7C formed.

  Accordingly, the height position T1 of the bottom surface of the linear exhaust port 13 in the height direction of the engine 1 is set to the bottom surface of the curved exhaust ports 11 and 12 in the height direction of the engine 1 by the thickness of the bulging portion 20. It can be formed at a position higher than the height position T2.

  For this reason, the passage area of the straight exhaust port 13 can be made smaller than the passage area of the curved exhaust ports 11 and 12. Therefore, it is possible to prevent the turbulent flow of the exhaust gas from occurring at the bulging portion 20 of the linear exhaust port 13 or prevent the stagnation of the exhaust gas and rectify the exhaust gas to flow to the exhaust collecting portion 14.

  In addition to this, the exhaust gas can be rectified without reducing the passage area of the curved exhaust ports 11, 12 with the curved exhaust ports 11, 12 without a rapid expansion of the passage area. For this reason, it is possible to reliably prevent the back pressure from increasing at the curved exhaust ports 11 and 12.

  Further, according to the cylinder head 3 of the present embodiment, the linear exhaust port 13 which is formed between the curved exhaust ports 11 and 12 and becomes higher in temperature than the curved exhaust ports 11 and 12 is cooled by the cooling water. can do. In addition, the volume of the water jacket 21B can be increased by the thickness of the bulging portion 20 formed in the linear exhaust port 13, and more cooling water can be circulated through the water jacket 21B. The cooling property of 13 can be improved.

  Further, as described above, when the cylinder head 3 is cut in a cross section perpendicular to the arrangement direction of the cylinders 6A to 6C and along the arrangement direction of the cylinders 6A to 6C, a linear shape in the height direction of the engine 1 is obtained. The height position T1 of the bottom surface of the exhaust port 13 is formed at a position higher than the height position T2 of the bottom surfaces of the curved exhaust ports 11 and 12 in the height direction of the engine 1.

  As a result, as shown in FIG. 3, the height direction gap t1 of the water jacket 21B can be made larger than the height direction gap t2 of the water jackets 21A and 21C. Therefore, the volume of the water jacket 21B can be increased more than the volume of the water jackets 21A and 21C. In the cylinder head 2 of the present embodiment, the bulging portion 20 is formed along the length direction of the inclined bottom surface 13b. The bulging portion 20 extends from the curved bottom surface 13a to the length direction of the inclined bottom surface 13b. It may be formed in a certain range.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine), 2 ... Cylinder block, 3 ... Cylinder head, 6A-6C ... Cylinder, 7A ... Combustion chamber (one end side combustion chamber), 7B ... Combustion chamber (intermediate combustion chamber), 7C ... Combustion chamber (other end side combustion chamber), 10 ... Exhaust port, 11, 12 ... Curved exhaust port, 13 ... Linear exhaust port, 13a ... curved bottom surface, 13b ... inclined bottom surface, 14 ... exhaust collecting portion, 18 ... reference surface, 19 ... virtual extension surface, 20 ... bulging portion, 23 ... bonding Surface, 21B ... Water jacket, 24 ... Cooling water inlet

Claims (4)

A cylinder head provided at an upper part of a cylinder block of an internal combustion engine having cylinders, having a plurality of combustion chambers along a cylinder row direction, and a plurality of exhaust ports communicating with the combustion chambers;
When the exhaust port is viewed from above, a plurality of the exhaust ports are formed integrally with the cylinder head and curved in the cylinder row direction after extending in a direction perpendicular to the cylinder row direction A linear exhaust port formed integrally with the cylinder head and having a passage length shorter than a passage length of the curved exhaust port and extending in a direction orthogonal to the cylinder row direction A port and an exhaust collecting part that is formed integrally with the cylinder head and collects the curved exhaust port and the downstream part of the linear exhaust port;
The linear exhaust port communicates with the combustion chamber, has a curved bottom surface that curves upward from the combustion chamber, and an inclined bottom surface that slopes obliquely upward from the curved bottom surface, and is directed from the combustion chamber to the exhaust collecting portion. The inner diameter gradually expands according to
When a bottom surface of the exhaust collecting portion is used as a reference surface, and the reference surface is provided with a virtual extension surface extending toward the upstream end side of the linear exhaust port, the bottom surface of the linear exhaust port is more than the virtual extension surface. Has a bulge that bulges upward,
The bulging portion is formed over the region to contact the bottom surface of the imaginary extension portion and the exhaust collector located above the surface of the curved bottom surface in a direction orthogonal to the cylinder row direction ,
In a cross section obtained by cutting the linear exhaust port along a plane parallel to the height direction of the cylinder head and parallel to the cylinder row direction, the bottom surface of the linear exhaust port constituted by the bulging portion is the cylinder row. A cylinder head for an internal combustion engine, wherein the cylinder head is formed so as to be a flat surface over the entire direction . A water jacket into which cooling water flows from the cylinder block is formed below the curved exhaust port and the linear exhaust port,
Forming a cooling water inlet that flows from the cylinder block on the joint surface of the cylinder block in the cylinder head,
2. The cylinder head of the internal combustion engine according to claim 1, wherein the cooling water introduction port is opened below the bulging portion so as to overlap in a height direction of the internal combustion engine. The combustion chamber has one end side combustion chamber formed at one end in the cylinder row direction, the other end side combustion chamber formed at the other end in the cylinder row direction, the one end side combustion chamber, and the other. An intermediate combustion chamber formed between the end side combustion chamber and
The curved exhaust port is composed of an exhaust port extending from the one end side combustion chamber and an exhaust port extending from the other end side combustion chamber,
The linear exhaust port is composed of an exhaust port extending from the intermediate combustion chamber;
Forming the bulging portion only in the linear exhaust port extending from the intermediate combustion chamber ;
The cylinder head of the internal combustion engine according to claim 1 or 2, wherein the bulging portion is smoothly connected to the exhaust collecting portion .   When the cylinder head is cut in a cross section perpendicular to the cylinder row direction and along the cylinder row direction, the height position of the bottom surface of the linear exhaust port in the height direction of the internal combustion engine is 4. The cylinder head of the internal combustion engine according to claim 3, wherein the cylinder head is formed at a position higher than a height position of a bottom surface of the curved exhaust port in the height direction of the internal combustion engine.

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