JP2020101090A - cylinder head - Google Patents

Abstract

To provide a cylinder head that suppresses accumulation of exhaust gas in an exhaust port by reducing interference of exhaust gas passing through different exhaust ports, lowers the temperature of the exhaust gas efficiently, and thus improving cooling performance.SOLUTION: An exhaust port 18 comprises a fillet part 130 in which an end part of at least one of an upper wall surface and a lower wall surface on a partition wall 21 side is formed into a curved shape, and of the pair of exhaust ports 18 confluent at a confluence part 100, the port length of one exhaust port 18 is longer than the port length of the other exhaust port 18. In the one exhaust port 18, the confluence part 100 is provided with an enlarged fillet part 140 in which the radius of the fillet part 130 is made larger than the radius of the fillet part 130 of the other exhaust port.SELECTED DRAWING: Figure 4

Description

TECHNICAL FIELD The present invention relates to a structure of a cylinder head including a collective exhaust port including a plurality of exhaust ports connected to a plurality of cylinders and an exhaust collecting section in which the plurality of exhaust ports are assembled.

Conventionally, for example, in a multi-cylinder engine, a plurality of exhaust ports corresponding to each cylinder are formed in a cylinder head. An exhaust manifold having a plurality of exhaust passages connected to each exhaust port is connected to the cylinder head, and the exhaust passages are joined in the exhaust manifold.

Further, a multi-cylinder engine has been developed in which an exhaust collecting portion for collecting a plurality of exhaust ports corresponding to each cylinder is formed in the cylinder head, and a single exhaust pipe is connected to the cylinder head.

Such a cylinder head becomes hot due to the influence of exhaust gas passing through the inside. For this reason, a cooling water passage (water jacket) for circulating cooling water is formed in the cylinder head. In particular, in the cylinder head in which the exhaust gas collecting portion is formed as described above, the exhaust gas may collect inside and the temperature tends to be high. Therefore, in the cylinder head having the exhaust collecting portion, the cooling performance is improved by the cooling water passage (water jacket).

For example, in a cylinder head integrally provided with a collective exhaust conduit formed by merging a plurality of exhaust conduits, a lower cooling jacket arranged below the exhaust conduit and an upper part arranged above the exhaust conduit. There is one in which a cooling liquid jacket and a communication portion which communicates the lower cooling jacket and the upper jacket and functions as a passage for the cooling liquid are provided (for example, refer to Patent Document 1).

According to the configuration of Patent Document 1, the cooling performance can be improved as compared with the conventional cylinder head.

JP, 2008-309158, A

However, even with the structure described in Patent Document 1, the cooling performance of the cylinder head is not always sufficient, and further improvement is desired.

In recent years, a cylinder head has, as a cooling water passage (cooling liquid passage), an upper passage provided above the collective exhaust port, and a lower passage provided below the collective exhaust port independently of the upper passage. Providing a structure is also proposed. In the cylinder head having such a structure, the cooling water can be separately supplied to the upper passage and the lower passage, so that cooling can be performed as compared with the conventional cylinder head in which the upper passage and the lower passage are integrally formed. Performance can be improved.

Even in the structure in which the upper passage and the lower passage are independent from each other as described above, when the exhaust gas discharged from each cylinder interferes with each other without heading toward the exhaust collecting portion side (discharging direction), the flow of the exhaust gas Becomes worse and exhaust gas cannot be cooled efficiently. Therefore, further improvement in the shape of the exhaust port is desired.

The present invention has been made in view of such circumstances, and suppresses the retention of exhaust gas in the exhaust port by reducing the interference between the exhaust gases passing through different exhaust ports, and the temperature of the exhaust gas is reduced. An object of the present invention is to provide a cylinder head that is efficiently lowered and has improved cooling performance.

One aspect of the present invention that solves the above-mentioned problems constitutes a multi-cylinder engine, and includes a plurality of exhaust ports connected to each of the plurality of cylinders, and an exhaust collecting portion in which the plurality of exhaust ports are collected. A cylinder head having a collective exhaust port including, a pair of adjacent exhaust ports being partitioned by a partition wall, and the pair of adjacent exhaust ports joining at a joining portion, wherein the exhaust port is an upper portion. At least one of the wall surface or the lower wall surface is provided with a fillet portion in which the end portion on the partition wall side is formed into a curved surface, and of the pair of exhaust ports that join at the joining portion, the port length of one exhaust port is the other. The one exhaust port is longer than the port length of the exhaust port, and the one of the exhaust ports is provided with an enlarged fillet portion in which the radius of the fillet portion is larger than the radius of the fillet portion of the other exhaust port, in the confluence portion. The cylinder head is characterized by.

Here, it is preferable that the enlarged fillet portion has the largest radius of the portion corresponding to the tip end portion on the downstream side in the exhaust flow direction of the partition wall.

Further, a projection portion protruding from at least one of the upper wall surface and the lower wall surface of the exhaust port into the exhaust port and extending from the tip end portion of the partition wall toward the exhaust gas collecting portion side is provided. The enlarged fillet portion is preferably provided in a region including a portion corresponding to the protruding portion.

Furthermore, it is preferable that the radius of the enlarged fillet portion is gradually reduced from the tip end side of the partition wall toward the tip end side of the ridge portion.

When the multi-cylinder engine is an in-line four-cylinder engine in which first to fourth cylinders are arranged in a line, the collective exhaust port is connected to the first to fourth cylinders from the first to the fourth cylinders. In addition to the four exhaust ports, the exhaust collecting portion is provided at the center of the cylinder in the row direction, and the first exhaust port and the second exhaust port are joined to each other at the merging portion. It is preferable that the exhaust port includes the enlarged fillet portion, and the fourth exhaust port includes the enlarged fillet portion at a confluence portion where the third exhaust port and the fourth exhaust port merge. ..

According to the cylinder head of the present invention, the temperature of the exhaust gas passing through the exhaust port can be efficiently lowered, and the cooling performance can be improved. Specifically, the flow of exhaust gas can be appropriately controlled by increasing the radius of the fillet portion of the exhaust port on the side where the port length is long in the confluence portion where adjacent exhaust ports merge.

Further, by appropriately controlling the flow of exhaust gas, it is possible to suppress exhaust interference between other exhaust ports, particularly between adjacent exhaust ports. That is, it is possible to prevent the exhaust gas flowing from the exhaust port having the longer port length from flowing into the exhaust port having the shorter port length.

Therefore, the temperature of the exhaust gas can be efficiently reduced, and the cooling performance of the cylinder head can be improved.

3A and 3B are a top view and a side view of the cylinder head according to the embodiment of the present invention. It is a sectional view of a cylinder head concerning one embodiment of the present invention. It is a figure which shows typically the collective exhaust port which concerns on one Embodiment of this invention. It is an enlarged view showing typically the collective exhaust port concerning one embodiment of the present invention. It is a sectional view of a cylinder head concerning one embodiment of the present invention. It is a sectional view of a cylinder head concerning one embodiment of the present invention. It is a figure which shows typically the water jacket which concerns on one Embodiment of this invention. It is a figure explaining the upper jacket which concerns on one Embodiment of this invention. It is a figure explaining the lower jacket which concerns on one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing an upper surface of a cylinder head (a surface opposite to a mounting surface on a cylinder block) and a side surface on a front side of the cylinder head. FIG. 2 is a sectional view taken along the line AA′ of the cylinder head. 3 is a diagram schematically showing the shape of the collective exhaust port as the shape of the sand core, and FIG. 4 is an enlarged view thereof. 5 and 6 are cross-sectional views schematically showing the cylinder head, FIG. 5 is a cross-sectional view corresponding to line BB′ in FIG. 4, and FIG. 6 is CC′ in FIG. It is sectional drawing corresponding to a line. FIG. 7 is a perspective view showing the shape of the water jacket as the shape of the sand core. FIG. 8 is a top view showing the shape of the water jacket, and FIG. 9 is a bottom view showing the shape of the water jacket.

The cylinder head 10 according to the present embodiment shown in FIG. 1 constitutes an air-cooled in-line four-cylinder engine including four cylinders (cylinders) arranged in series (one row) from the front side (vehicle front side). A cylinder block (not shown) in which first to fourth cylinders (cylinders) 11 (11a to 11d) are formed is attached to the lower surface 10a of the cylinder head 10.

On the other hand, a valve operating chamber 12 is formed on the upper surface 10b of the cylinder head 10. Although illustration is omitted, a valve operating mechanism for driving an intake valve and an exhaust valve is housed in the valve operating chamber 12, and a cylinder cover for covering the valve operating chamber 12 is attached to the upper surface of the cylinder head 10.

The present invention is characterized by the internal structure of the cylinder head 10 that constitutes such a water-cooled multi-cylinder engine. Hereinafter, the internal structure of the cylinder head 10 will be described in detail.

As shown in FIGS. 1 and 2, the cylinder head 10 is provided with two intake valve holes 13 (13a, 13b) corresponding to each cylinder 11 and two exhaust valve holes 14 (14a, 14b). ing. That is, the cylinder head 10 is provided with eight intake valve holes 13 and eight exhaust valve holes 14.

Further, the cylinder head 10 is provided with four intake ports 15 corresponding to each cylinder 11. One end side of each intake port 15 is connected to two intake valve holes 13 corresponding to each cylinder 11. These intake ports 15 are provided independently of each other without gathering, and open on one side surface 10c of the cylinder head 10, respectively. That is, four intake ports 16 connected to each cylinder 11 are formed on the side surface 10c of the cylinder head 10 (see FIG. 1).

Further, the cylinder head 10 is provided with a collective exhaust port 17 connected to each of the cylinders 11. The collective exhaust port 17 is configured to include four exhaust ports 18 (18a to 18d) connected to each cylinder 11 and an exhaust collecting unit 19 in which these exhaust ports 18 (18a to 18d) are assembled. There is.

One end side of each exhaust port 18 is connected to the two exhaust valve holes 14a and 14b corresponding to each cylinder 11, and the other end side of each exhaust port 18 is gathered at the exhaust gathering part 19.

More specifically, as shown in the schematic view of FIG. 3, each exhaust port 18 includes a pair of branch passage portions 181 and 182 connected to the exhaust valve holes 14a and 14b, and a pair of branch passage portions 181 and 182. It is configured with a trunk passage portion 183 that merges. The trunk passage portions 183 of the first to fourth exhaust ports 18 (18a to 18d) are gathered at the exhaust gathering portion 19.

The exhaust collecting portion 19 is located at the center of the cylinder 11 in the direction in which the cylinders 11 are arranged (the front-rear direction of the cylinder head 10), and is opened on the side surface 10d opposite to the side surface 10c where the intake port 16 of the cylinder head 10 is opened. There is. That is, on the side surface 10d of the cylinder head 10, one exhaust port 20 through which the exhaust gas collected in the exhaust collecting portion 19 flows is formed in the central portion in the cylinder arranging direction (the front and rear direction of the cylinder head 10). ing.

Further, the exhaust ports 18 (the trunk passage portions 183) are partitioned by the first partition wall 21 (21a to 21c), and the pair of adjacent exhaust ports 18 join at the joining portion 100 (100A to 100C). ing. In other words, the pair of adjacent exhaust ports 18 meet at the tip of the first partition wall 21 (the end on the exhaust collecting portion 19 side, the end on the downstream side in the exhaust flow direction). That is, the area near the tip of the first partition wall 21 becomes the merging portion 100 (100A to 100C) where the pair of adjacent exhaust ports 18 merge.

Here, each of the merging portions 100 is provided with a ridge portion 110 that projects into the exhaust port 18 from at least one of the upper wall surface and the lower wall surface of the exhaust port 18, and the ridge portion 110 includes each first partition wall. It extends from the tip of 21 toward the exhaust collecting portion 19 side. The protrusion 110 may be provided on one of the upper wall surface and the lower wall surface of the exhaust port 18, or may be provided on both. In the present embodiment, the protrusion 110 is provided on the upper wall surface of the exhaust port 18 (see FIG. 6). Exhaust interference between adjacent exhaust ports 18 is suppressed by the provision of the ridge 110.

In addition, the space between the branch passages 181 and 182 forming each exhaust port 18 is partitioned by a second partition wall 22 (22a to 22d), and the vicinity region including the tip of the second partition wall 22 is The branch passages 181 and 182 of each exhaust port 18 serve as a branch merging portion 120.

The branch merging portion 120 is also provided with a ridge portion 111 that projects into the exhaust port 18 from at least one of the upper wall surface and the lower wall surface of the exhaust port 18, and the ridge portion 111 of the second partition wall 22 is provided. It extends from the tip end toward the exhaust collecting portion 19 side. The lengths of the protrusions 110 and 111 are not particularly limited and may be appropriately determined in consideration of the flow of exhaust gas.

Here, as shown in FIG. 4 and FIG. 5, each exhaust port 18 (stem passage 183) is formed in a substantially rectangular opening shape, and its four corners are rounded fillets. It is a part 130. That is, each exhaust port 18 is provided with fillet portions 130 at both ends of its upper wall surface and lower wall surface.

Then, in each merging portion 100 where the pair of exhaust ports 18 merge, when the port length of one exhaust port 18 (the length from the cylinder 11 to the exhaust collecting portion 19) is longer than the port length of the other exhaust port, As shown in FIGS. 4 and 6, the one exhaust port 18 is provided with an enlarged fillet portion 140 in which the radius of the fillet portion 130 is increased (enlarged). Specifically, the enlarged fillet portion 140 is larger than the radius of the fillet portion 130 of the other exhaust port 18 in each confluence portion 100.

In the present embodiment, the port length of the first exhaust port 18a is longer than the port length of the adjacent second exhaust port 18b, and the port length of the fourth exhaust port 18d is adjacent to the third exhaust port 18d. It is longer than the port length of the exhaust port 18c.

Therefore, in the merging portion 100A where the first exhaust port 18a (the main passage portion 183) and the second exhaust port 18b (the main passage portion 183) merge, the first exhaust port 18a forms the enlarged fillet portion 140. I have it. Similarly, in the merging portion 100C where the third exhaust port 18c and the fourth exhaust port 18d merge, the fourth exhaust port 18d includes the enlarged fillet portion 140 (see FIG. 3).

In the merging portion 100B where the second exhaust port 18b and the third exhaust port 18c merge, the port length of the second exhaust port 18b and the port length of the third exhaust port 18c are substantially the same. Therefore, the expanded fillet portion 140 is not provided on either the second exhaust port 18b or the third exhaust port 18c.

As described above, the first exhaust port 18a in the merging portion 100A includes the enlarged fillet portion 140, and the fourth exhaust port 18d in the merging portion 100C includes the enlarged fillet portion 140. The flow of the exhaust gas in the first exhaust port 18a and the fourth exhaust port 18d can be appropriately controlled. Therefore, exhaust interference with the other exhaust port 18 can be suppressed.

Specifically, it is possible to suppress the exhaust gas flowing from the exhaust port having the longer port length from flowing into the exhaust port having the shorter port length. Specifically, the exhaust gas discharged from the first exhaust port 18a and the fourth exhaust port 18d can be suppressed from flowing into the adjacent port.

Further, it is possible to prevent exhaust gas discharged from the port having a long port length from flowing in a direction different from that of the exhaust port 20. Specifically, the exhaust gas discharged from the first exhaust port 18a and the fourth exhaust port 18d can be controlled toward the exhaust port 20. For example, it is possible to prevent the exhaust gas flowing out from the first exhaust port 18a from flowing into the fourth exhaust port 18d. As a result, the exhaust gas discharged from the exhaust port 18 can be discharged from the exhaust port 20 relatively early.

Furthermore, by exhausting the exhaust gas discharged from the exhaust port having a long port length from the exhaust port 20 relatively early, it is possible to suppress mixing with the exhaust gas flowing out from different exhaust ports having a short port length. Becomes

The expanded fillet portion 140 may be provided in each confluence portion 100, and its installation range is not particularly limited, but it is preferable that the enlarged fillet portion 140 is provided in a range including a portion corresponding to the ridge portion 110. Accordingly, the ridge 110 and the enlarged fillet 140 can appropriately control the flow of exhaust gas toward the exhaust port 20 side.

Further, the enlarged fillet portion 140 has a larger radius at each portion than the radius of the fillet portion 130 of the other exhaust port 18 provided at the confluence portion 100. However, the radii of the respective portions of the enlarged fillet portion 140 are not the same, and in the present embodiment, the portion corresponding to the tip end portion of the first partition wall 21 is the maximum. By forming the enlarged fillet portion 140 in such a shape, it is possible to suppress the exhaust gas flowing from the exhaust port having the longer port length from flowing into the exhaust port having the shorter port length, and to further increase the flow of the exhaust gas. It can be controlled appropriately.

In addition, the radius of the enlarged fillet portion 140 is gradually reduced from the portion corresponding to the tip end portion of the first partition wall 21 toward the tip end portion side (downstream side) of the protrusion 110. By forming the enlarged fillet portion 140 in such a shape, the flow of exhaust gas can be further appropriately controlled to the exhaust port side.

In the present embodiment, the radius of the enlarged fillet portion 140 is gradually reduced toward the downstream side. However, the radius of each part of the enlarged fillet portion 140 is not particularly limited, and for example, the enlarged fillet portion 140 may be used. The size may be the same in each part of. The size of the radius of each portion of the enlarged fillet portion 140 may be appropriately determined in consideration of the flow of exhaust gas and the like.

As described above, in the cylinder head 10 according to the present embodiment, when one of the adjacent exhaust ports 18 has a longer port length than the other, the enlarged fillet portion 140 is provided in the merging portion 100. It is possible to properly control the flow of exhaust gas passing through the vicinity. Therefore, it is possible to suppress exhaust interference and the like between the adjacent exhaust ports 18, and it is possible to suppress the temperature rise of the exhaust gas. Accordingly, the cooling performance of the cylinder head 10 can be improved.

Further, as described below, the cylinder head 10 is provided with the water jacket 30, and the expansion fillet portion 140 appropriately controls the flow of the exhaust gas, so that the cooling water flowing through the water jacket 30 can also be used. Exhaust gas can be cooled efficiently. Therefore, the cooling performance of the cylinder head 10 can be further improved.

The cylinder head 10 is integrally formed with a water jacket (cooling water passage) 30 for circulating cooling water in the direction in which the cylinders 11 are arranged. In the present embodiment, cooling water is circulated through the water jacket 30 from the front side to the rear side of the cylinder head 10, so that the temperature rise in the vicinity of each cylinder (combustion chamber) 11 and the collective exhaust port 17 due to exhaust heat. Is suppressed.

As shown in FIG. 7, the water jacket 30 according to this embodiment includes an upper jacket (first passage) 31 provided above the collective exhaust port 17 and a lower jacket (first passage) provided below the collective exhaust port 17. 2) 32).

As shown in FIGS. 7 and 8, the upper jacket (first passage) 31 covers a cylinder passage portion 33 provided above each cylinder 11 and an upper portion of the collective exhaust port 17 above the collective exhaust port 17. And the port passage portion 34 provided as described above. That is, in the upper jacket 31, two main flows of the cooling water are formed, which flow through the cylinder passage portion 33 and the port passage portion 34.

It should be noted that the cylinder passage portion 33 and the port passage portion 34 are disposed outside the exhaust valve hole 14a corresponding to the first cylinder 11a and outside the exhaust valve hole 14b corresponding to the fourth cylinder 11d, and adjacent to the exhaust valve hole. 14 communicate with each other.

On the other hand, the lower jacket (second passage) 32 is not provided in the portion corresponding to each cylinder 11 as shown in FIGS. 7 and 9, and is provided below the collective exhaust port 17 under the collective exhaust port 17. The port passage portion 35 is provided so as to cover the lower part of the.

Here, the upper jacket 31 and the lower jacket 32 are provided independently. That is, the upper jacket 31 and the lower jacket 32 are formed so that the cooling water is supplied from different paths.

The upper jacket 31 has one upper inlet passage portion 36 to which cooling water is supplied on the front side of the cylinder head 10 and an upper outlet passage portion 37 on the rear side of the cylinder head 10. That is, the cooling water is supplied into the upper jacket 31 from the upper inlet passage portion 36, and the supplied cooling water is discharged to the outside from the upper outlet passage portion 37 after passing through the cylinder passage portion 33 and the port passage portion 34. It is supposed to be done. The upper outlet passage portion 37 does not necessarily have to be one, and a plurality of upper outlet passage portions 37 may be provided.

On the other hand, the lower jacket 32 has a lower inlet passage portion 38, which is independent of the upper inlet passage portion 36, on the front side of the cylinder head 10. Inside the lower jacket 32, cooling is performed from the lower inlet passage portion 38. Water is supplied. The lower jacket 32 is connected to the upper jacket 31 on the rear side of the cylinder head 10 (downstream side in the flow direction of the cooling water). That is, the cooling water supplied into the lower jacket 32 passes through the port passage portion 35 and is then discharged to the outside through the upper outlet passage portion 37 of the upper jacket 31.

Specifically, the lower jacket 32 includes a sub passage portion 39 that extends from the vicinity of the downstream end portion of the port passage portion 35 along the direction in which the cylinders 11 are arranged. On the other hand, the upper jacket 31 has a branch passage portion 40 that branches from the upper outlet passage portion 37 and extends toward the sub passage portion 39. The sub passage portion 39 of the lower jacket 32 is connected to the branch passage portion 40. In the present embodiment, the sub passage portion 39 has a large diameter portion 39a having a diameter larger than the diameter of the connection portion with the port passage portion 35, and at the large diameter portion 39a, the branch passage portion 40 of the upper jacket 31. It is connected to the.

That is, in the cylinder head 10 according to the present embodiment, the cooling water supplied into the lower jacket 32 passes through the port passage portion 35 and the sub passage portion 39, and then passes through the branch passage portion 40 of the upper jacket 31 to the upper portion. It is designed to be discharged from the outlet passage portion 37 to the outside.

The sub passage portion 39 of the lower jacket 32 is a space formed by a skirting board that supports a core for forming the port passage portion 35 when the cylinder head 10 is cast. Therefore, the front end portion (downstream end portion) of the sub passage portion 39 is open, but the opening of the sub passage portion 39 is sealed by a sealing member (expansion plug) not shown.

In this way, the port passage portion 35 constituting the lower jacket 32 is communicated with the branch passage portion 40 of the upper jacket 31 via the sub passage portion 39 extending from the vicinity of the downstream end portion of the port passage portion 35. Thus, the cooling water can be satisfactorily circulated in the lower jacket 32 without obstructing the flow of the cooling water in the port passage portion 35 in the lower jacket 32.

Further, since the sub passage portion 39 is connected to the branch passage portion 40 on the downstream side of the cylinder passage portion 33 and the port passage portion 34 of the upper jacket 31, the sub passage portion 39 of the cylinder passage 33 and the port passage portion 34 of the upper jacket 31 is connected. The cooling water can be satisfactorily circulated in the upper jacket 31 without obstructing the flow.

That is, since the cooling water can be satisfactorily circulated in each of the upper jacket 31 and the lower jacket 32, the cooling performance of the cylinder head 10 can be improved.

Further, since the upper jacket 31 and the lower jacket 32 are provided independently, it is necessary to process the cylinder head 10 after casting in order to connect the upper jacket 31 and the lower jacket 32. That is, at the time of casting, the sub passage portion 39 and the branch passage portion 40 are separated from each other. Therefore, it is necessary to process the cylinder head 10 after that so that the sub passage portion 39 and the branch passage portion 40 communicate with each other.

In the present embodiment, the sub passage portion 39 of the lower jacket 32 is a space formed by the skirting board that supports the core, and the tip portion thereof is in the open state, so the sub passage portion 39 and the branch passage portion 40 are provided. The process for communicating with and can be performed relatively easily.

As described above, the cylinder head 10 can suppress the temperature rise of the cylinder head 10 by the cooling water flowing through the water jacket 30, but the predetermined exhaust port 18 further includes the enlarged fillet portion 140 at the confluence portion 100. Therefore, the temperature rise of the cylinder head 10 can be suppressed more effectively.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. The present invention can be appropriately modified without departing from the spirit thereof.
For example, in the above-described embodiment, the enlarged fillet portion is provided in one of the exhaust ports in the merging portion 100, but it goes without saying that the branch merging portion 120 may also be provided with the enlarged fillet portion as necessary. ..

Further, for example, in the above-described embodiment, the present invention has been described by exemplifying an inline 4-cylinder engine as the engine, but the cylinder head according to the present invention is, of course, a cylinder head constituting an engine other than an inline 4-cylinder engine. Is also applicable.

10 cylinder head 11 cylinder (cylinder)
12 Valve Chamber 13 Intake Valve Hole 14 Exhaust Valve Hole 15 Intake Port 16 Intake Port 17 Collective Exhaust Port 18 Exhaust Port 19 Exhaust Collecting Port 20 Exhaust Port 21 First Partition Wall 22 Second Partition Wall 30 Water Jacket 31 Upper Jacket 32 Lower Jacket 33 Cylinder Passage 34, 35 Port Passage 36 Upper Entrance Passage 37 Upper Outlet Passage 38 Lower Inlet Passage 39 Sub Passage 40 Branch Passage 100 Confluence 110,111 Projection 120 120 Branch Confluence 130 Fillet part 140 Expanded fillet part 181,182 Branch passage part 183 Trunk passage part

Claims (5)

Configuring a multi-cylinder engine,
A collective exhaust port including a plurality of exhaust ports connected to each of the plurality of cylinders, and an exhaust collecting portion in which the plurality of exhaust ports are assembled is provided, and a pair of adjacent exhaust ports are partitioned by a partition wall. In addition, the pair of adjacent exhaust ports is a cylinder head that joins at a joining portion,
The exhaust port includes a fillet portion in which at least one of an upper wall surface and a lower wall surface, the end portion on the partition wall side is formed into a curved surface,
Of the pair of exhaust ports that join at the merging portion, the port length of one exhaust port is longer than the port length of the other exhaust port,
The cylinder head, wherein the one exhaust port is provided with an enlarged fillet portion in which the radius of the fillet portion is larger than a radius of the fillet portion of the other exhaust port, in the confluence portion. The cylinder head according to claim 1, wherein
The cylinder head, wherein the enlarged fillet portion has the largest radius at a portion corresponding to a tip end portion on the downstream side in the exhaust flow direction of the partition wall. The cylinder head according to claim 1 or 2, wherein
A protrusion extending from at least one of the upper wall surface and the lower wall surface of the exhaust port into the exhaust port and extending from the tip end of the partition wall toward the exhaust collecting portion side;
The cylinder head, wherein the enlarged fillet portion is provided in a region including a portion corresponding to the protruding portion. The cylinder head according to claim 3,
The cylinder head, wherein the radius of the enlarged fillet portion is gradually reduced from the tip end side of the partition wall toward the tip end side of the ridge portion. The cylinder head according to any one of claims 1 to 4,
The multi-cylinder engine is an in-line four-cylinder engine in which first to fourth cylinders are arranged in a line.
The collective exhaust port includes first to fourth exhaust ports connected to the first to fourth cylinders, and the exhaust collecting section is provided at the center of the cylinder in the row direction,
In the merging portion where the first exhaust port and the second exhaust port merge, the first exhaust port includes the enlarged fillet portion, and the third exhaust port and the fourth exhaust port are In the merging portion that merges, the fourth exhaust port includes the enlarged fillet portion.

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