JP7151785B2 - cylinder head - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a cylinder head of a multi-cylinder engine, and more particularly to a structure of cooling water passages (water jackets) provided inside the cylinder head.

Conventionally, a plurality of exhaust ports corresponding to each cylinder were formed in the cylinder head of a multi-cylinder engine. 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 merged within the exhaust manifold.

In addition, a multi-cylinder engine was developed in which a single exhaust pipe is connected to the cylinder head by forming an exhaust collecting section that collects multiple exhaust ports corresponding to each cylinder in the cylinder head. It is
Such a cylinder head becomes hot due to the influence of the exhaust gas passing through it. For this reason, a cooling water passage (water jacket) for circulating cooling water is formed in the cylinder head. In particular, the cylinder head in which the exhaust collecting portion is formed inside as described above tends to become hot because the exhaust collects inside. Therefore, in a cylinder head having an exhaust collecting portion, cooling performance is improved by a cooling water passage (water jacket).

For example, in a cylinder head integrally provided with a collective exhaust duct formed by merging a plurality of exhaust ducts, a lower coolant jacket disposed below the exhaust duct and a coolant jacket disposed above the exhaust duct There is one that includes an upper cooling liquid jacket and a communicating portion that connects the lower cooling liquid jacket and the upper cooling liquid jacket and functions as a cooling liquid passage (for example, Japanese Patent Application Laid-Open No. 2008-309158). (see Gazette).

According to the configuration disclosed in Japanese Patent Application Laid-Open No. 2008-309158, the cooling performance can be improved as compared with the conventional cylinder head.
However, even with the configuration disclosed in Japanese Patent Application Laid-Open No. 2008-309158, the cooling performance of the cylinder head is not necessarily sufficient, and further improvement is desired.

In recent years, a structure in which a cylinder head is provided with an upper passage provided above the exhaust port and a lower passage provided below the exhaust port independently of the upper passage as cooling water passages (coolant passages) is also proposed. In the cylinder head with such a structure, cooling water can be supplied to the upper passage and the lower passage separately, so the cooling performance can be improved compared to the conventional cylinder head in which the upper passage and the lower passage communicate with each other. can be done.

Further, even with such a structure in which the upper passage and the lower passage are independent, the cooling performance of the cylinder head is still insufficient, and further improvement is desired.

The present disclosure provides a cylinder head in which cooling water is circulated in a cooling water passage, and in which cooling performance is further improved.

According to one aspect of the present invention, a cylinder head of a multi-cylinder engine includes: a plurality of exhaust ports respectively connected to a plurality of cylinders; an exhaust collecting portion configured to collect the plurality of exhaust ports; and a cooling water passage configured to flow cooling water in a row direction in which the plurality of cylinders are arranged side by side. The cooling water passage includes an upper passage provided above the collective exhaust port and a lower passage provided below the collective exhaust port facing the upper passage. The lower passage includes a port passage portion provided corresponding to the collective exhaust port, and a sub-passage portion extending along the row direction of the cylinders from the downstream side of the port passage portion. The lower passage communicates with the upper passage through the sub passage portion.

According to another aspect of the present invention, the sub passage has a large diameter portion that is larger in diameter than the diameter of the connection portion with the port passage. The large-diameter portion of the sub-passage is connected to the upper passage.

According to another aspect of the present invention, the upper passage includes a cylinder passage portion arranged corresponding to the plurality of cylinders arranged side by side, and a port passage portion arranged corresponding to the collective exhaust port. and an outlet passage portion extending in the row direction of the cylinders from the downstream side of the cylinder passage portion. The sub passage portion is connected to the outlet passage portion.

According to another aspect of the present invention, the upper passage has a branch passage extending from the outlet passage in a direction intersecting with the row direction of the cylinders. The sub passage portion is connected to the outlet passage portion through the branch passage portion.

According to another aspect of the invention, the subpassage portion of the lower passageway is formed by a skirting board on which a core forming the port passageway is supported.

According to the aspect of the present invention, the port passage portion of the lower passage communicates with the upper jacket via the sub-passage portion extending from the downstream side of the port passage portion. The cooling water can be well circulated in the lower passage without obstructing the flow of the cooling water. Therefore, it is possible to improve the cooling performance of the cylinder head by circulating the cooling water through the cooling water passage.

It is a top view of a cylinder head concerning one embodiment of the present invention. It is a side 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. FIG. 4 is a diagram illustrating an upper jacket according to one embodiment of the present invention; It is a figure explaining the lower jacket which concerns on one Embodiment of this invention. FIG. 2 is a cross-sectional view taken along the line BB' of the cylinder head according to one embodiment of the present invention; FIG. 4 is an enlarged cross-sectional view of the vicinity of the intra-wall passage portion according to the embodiment of the present invention; It is a sectional view of a cylinder head concerning one embodiment of the present invention.

An embodiment of the present invention will now be described in detail with reference to the drawings.

FIG. 1A is a diagram showing the upper surface of the cylinder head (the surface opposite to the mounting surface to the cylinder block), and FIG. 1B is a diagram showing the front side surface of the cylinder head. FIG. 2 is a sectional view taken along the line AA' of the cylinder head. FIG. 3 is a perspective view showing the shape of the water jacket as the shape of the sand core. FIG. 4 is a top view showing the shape of the water jacket, and FIG. 5 is a bottom view showing the shape of the water jacket. 6A-6B and FIG. 7 are diagrams for explaining the in-wall passage, FIG. 6A being a sectional view taken along line BB' of the cylinder head, and FIG. 6B being an enlarged sectional view of the vicinity of the in-wall passage. . FIG. 7 is a cross-sectional view corresponding to line CC' of the cylinder head.

A cylinder head 10 according to the present embodiment shown in FIGS. 1A-B constitutes an air-cooled in-line four-cylinder engine having 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 11 are formed is attached to the lower surface 10a of the cylinder head 10. As shown in FIG.

On the other hand, a valve operating chamber 12 is formed in the upper surface 10b of the cylinder head 10. As shown in FIG. Although not shown, a valve mechanism for driving intake valves and exhaust valves is accommodated in the valve chamber 12 , and a cylinder cover is attached to the upper surface of the cylinder head 10 to cover the valve chamber 12 .

The present disclosure is characterized by the internal structure of the cylinder head 10 that constitutes such a water-cooled multi-cylinder engine, particularly the structure of the water jacket (cooling water passage) provided in the cylinder head 10 . Below, the internal structure of the cylinder head 10 will be described in detail.

As shown in FIGS. 1A-B and 2, the cylinder head 10 has two intake valve holes 13 (13a, 13b) and two exhaust valve holes 14 (14a, 14b) corresponding to each cylinder 11. is provided. That is, a total of eight intake valve holes 13 and eight exhaust valve holes 14 are provided in the cylinder head 10 .

Also, the cylinder head 10 is provided with four intake ports 15 corresponding to each cylinder 11 . One end 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 without assembling together, and open to one side surface 10c of the cylinder head 10, respectively. That is, four air intake ports 16 respectively connected to the cylinders 11 are formed in the side surface 10c of the cylinder head 10 (see FIGS. 1A and 1B).

The cylinder head 10 is also provided with a collective exhaust port 17 connected to each cylinder 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 collective portion 19 where these exhaust ports 18 (18a to 18d) are collectively assembled. ing.

One end side of each exhaust port 18 is connected to two exhaust valve holes 14 a and 14 b corresponding to each cylinder 11 , and the other end side of each exhaust port 18 is gathered at an exhaust gathering portion 19 . The exhaust collecting portion 19 is located in the central portion in the direction in which the cylinders 11 are arranged (the longitudinal direction of the cylinder head 10, the direction in which the cylinders 11 are arranged side by side), and the side surface 10c of the cylinder head 10 where the intake port 16 opens. is opened on the side surface 10d opposite to the side surface 10d. That is, the side surface 10d of the cylinder head 10 has one exhaust port 20 through which the exhaust collected by the exhaust collecting portion 19 flows out, and is formed in the central portion in the direction in which the cylinders are arranged (the longitudinal direction of the cylinder head 10). there is

Each exhaust port 18 is partitioned between adjacent exhaust ports 18 by partition walls 21 (21a to 21c). These partition walls 21 are provided with a predetermined length toward the exhaust collecting portion 19 . The length of these partition walls 21 may be determined as appropriate. Moreover, it is preferable that the lengths of these partition walls 21 are set so that exhaust interference between at least adjacent exhaust ports 18 can be suppressed.

For example, an exhaust port 18b corresponding to the second cylinder 11b located in the central part of the cylinder head 10 (located inside of the four cylinders in the row direction) and an exhaust port corresponding to the third cylinder 11c. It is preferable that the partition wall 21b that separates the air outlet 18c extends to the vicinity of the exhaust port 20. As shown in FIG. As a result, the partition wall 21b can suppress the exhaust interference between the adjacent exhaust ports 18b and 18c, and the exhaust port 18a corresponding to the first cylinder 11a and the exhaust port 18a corresponding to the fourth cylinder 11d. Exhaust interference with the port 18d can also be suppressed.

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

As shown in FIG. 3, the water jacket 30 according to the present embodiment includes an upper jacket (upper passage) 31 provided above the collective exhaust port 17 and a lower jacket (lower passage) provided below the collective exhaust port 17. 32 and .

3 and 4, the upper jacket 31 includes a cylinder passage portion 33 provided above each cylinder 11 and a port passage provided above the collective exhaust port 17 so as to cover the upper portion of the collective exhaust port 17. a portion 34; That is, in the upper jacket 31, two flows, which flow through the cylinder passage portion 33 and the port passage portion 34, are formed as main flows of cooling water.

The cylinder passage portion 33 and the port passage portion 34 are defined as the outside of the exhaust valve hole 14a corresponding to the first cylinder 11a, the outside of the exhaust valve hole 14b corresponding to the fourth cylinder 11d, and the adjacent exhaust valve holes. 14 are in communication with each other.

On the other hand, as shown in FIGS. 3 and 5, the lower jacket 32 is not provided in the portion corresponding to each cylinder 11, but is positioned below the collective exhaust port 17 so as to cover the lower portion of the collective exhaust port 17. It is configured by a port passage portion 35 provided.

Here, the upper jacket 31 and the lower jacket 32 are provided so as to face each other independently. That is, the cooling water is supplied to the upper jacket 31 and the lower jacket 32 through separate 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, cooling water is supplied from the upper inlet passage portion 36 into the upper jacket 31, 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 designed to be Note that the number of the upper outlet passage portions 37 may not necessarily be one, and a plurality of them may be provided.

On the other hand, the lower jacket 32 has a lower inlet passage portion 38 independent of the upper inlet passage portion 36 on the front side of the cylinder head 10 . 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 is discharged to the outside through the upper outlet passage portion 37 of the upper jacket 31 after passing through the port passage portion 35 .

Specifically, the lower jacket 32 includes a sub-passage portion 39 extending 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 this branch passage portion 40 . In this embodiment, the sub-passage portion 39 has a large-diameter portion 39a having a larger diameter than the diameter of the connection portion with the port passage portion 35, and the branch passage portion 40 of the upper jacket 31 at the large-diameter portion 39a. 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. It is designed to be discharged to the outside from the outlet passage portion 37 .

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

Thus, the port passage portion 35 that constitutes the lower jacket 32 communicates with the branch passage portion 40 of the upper jacket 31 via the sub-passage portion 39 that extends from the vicinity of the downstream end portion of the port passage portion 35 . Thus, the cooling water can be well 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 downstream of the cylinder passage portion 33 and the port passage portion 34 of the upper jacket 31, the cylinder passage portion 33 and the port passage portion 34 of the upper jacket 31 The cooling water can be well circulated in the upper jacket 31 without any obstruction of the flow.

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

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

In this embodiment, the sub-passage portion 39 of the lower jacket 32 is a space formed by the baseboard that supports the core, and the tip portion thereof is open. It is possible to relatively easily perform processing for communicating with.

By the way, at least one of the upper jacket 31 and the lower jacket 32 that constitute the water jacket 30 has an in-wall passage provided in the partition wall 21 and extending toward the other jacket. In this embodiment, each of the upper jacket 31 and the lower jacket 32 has an in-wall passage portion as described below.

As shown in FIGS. 6A-B and 7, the port passage portion 35 of the lower jacket 32 extends toward the upper jacket 31 within the partition wall 21b separating the exhaust port 18b and the exhaust port 18c. It has an intra-wall passage portion 42 that is connected to the wall. The port passage portion 35 mainly extends below the collective exhaust port 17 along the direction in which the cylinders are arranged. It has an extended in-wall passageway 42 . The in-wall passage portion 42 extends along the inner surface of each of the two adjacent exhaust ports 18b and 18c to near the center in the height direction of the partition wall 21b.

On the other hand, the port passage portion 34 of the upper jacket 31 also extends mainly above the collective exhaust port 17 along the direction in which the cylinders are arranged. It has an in-wall passage portion 43 extending downwardly. The in-wall passage portion 43 also extends to the vicinity of the center in the height direction of the partition wall 21b.

The temperature of the partition wall 21b is likely to rise because it is affected by the heat of the exhaust gas passing through the plurality of exhaust ports 18. It is possible to effectively suppress the temperature rise of the partition wall 21b due to heat.

In other words, according to the structure of the cylinder head 10 according to the present embodiment, the partition wall 21 can suppress exhaust interference, and the cooling performance of the cylinder head 10 can be improved by circulating cooling water through the water jacket 30. can be done.

Further, the partition wall 21b is formed with a communication hole 44 that communicates between the in-wall passage portion 42 of the lower jacket 32 and the upper jacket 31. As shown in FIG. In the present embodiment, a communication hole 44 is formed at the boundary between the in-wall passage portion 42 of the lower jacket 32 and the in-wall passage portion 43 of the upper jacket 31 to communicate the two. That is, the uppermost portion of the in-wall passage portion 42 of the lower jacket 32 communicates with the in-wall passage portion 43 of the upper jacket 31 through the communication hole 44 .

Since the in-wall passage portion 42 of the lower jacket 32 extends toward the upper jacket 31 (upward), when the cooling water contains air bubbles, the air bubbles tend to stay in the in-wall passage portion 42. . However, since the communicating hole 44 is provided, air bubbles are discharged to the in-wall passage portion 43 side of the upper jacket 31 through the communicating hole 44 .

The communication hole 44 is a hole for venting air, and is formed with a relatively small diameter so that the air remaining in the in-wall passage portion 42 of the lower jacket 32 can escape. Therefore, air bubbles pass through the communication hole 44 , but the amount of cooling water flowing through the in-wall passage portion 42 that passes through the communication hole 44 is extremely small. In other words, even though the communication hole 44 is formed, the upper jacket 31 and the lower jacket 32 are kept independent, and the cooling water is supplied to the upper jacket 31 and the lower jacket 32 through separate paths as described above. circulate.

Therefore, since the communication hole 44 is formed, the cooling water can be well circulated to each of the lower jacket 32 including the in-wall passage portion 42 and the upper jacket 31 including the in-wall passage portion 43. Each part of the cylinder head 10 including the partition wall 21b can be cooled more appropriately.

The communication hole 44 may be provided at any position of the in-wall passage portion 42, but is preferably provided at the uppermost portion. As a result, air bubbles in the in-wall passage portion 42 can be more reliably discharged to the upper jacket 31 side. In this embodiment, an example in which the in-wall passage portions 42 and 43 are provided in the partition wall 21b has been described, but these in-wall passage portions 42 and 43 may be provided in other partition walls 21a and 21c.

While one embodiment of the invention has been described as described above, the disclosure is not limited to the above-described embodiment. The present disclosure can be modified as appropriate without departing from its gist.

For example, in the above-described embodiment, the sub-passage portion of the lower jacket is connected to the branch flow-path portion of the upper jacket, but the sub-passage portion may be connected to any part of the upper jacket. good.

In the above-described embodiment, the upper jacket and the lower jacket each have an in-wall passage in the partition wall, but only the lower jacket may have the in-wall passage, or the upper jacket may Only the wall may have an intra-wall passage. Further, when the lower jacket has an in-wall passage portion, it is preferable to provide a communication hole for communicating between the in-wall passage portion of the lower jacket and the upper jacket.

Further, in the above-described embodiment, the present disclosure has been described by exemplifying an in-line four-cylinder engine as a multi-cylinder engine, but the cylinder head according to the present disclosure can also be applied to multi-cylinder engines other than in-line four-cylinder engines. is.

This application is based on Japanese Patent Application No. 2018-237725 filed on December 19, 2018, the contents of which are incorporated herein by reference.

10 cylinder head 11 cylinder (cylinder)
11a to 11d first to fourth cylinders 12 valve chamber 13 (13a, 13b) intake valve hole 14 (14a, 14b) exhaust valve hole 15 intake port 16 intake port 17 collective exhaust port 18 (18a to 18d) exhaust port 19 exhaust collecting portion 20 exhaust port 21 (21a to 21c) partition wall 30 water jacket 31 upper jacket 32 lower jacket 33 cylinder passage portion 34, 35 port passage portion 36 upper inlet passage portion 37 upper outlet passage portion 38 lower inlet passage portion 39 Sub passage portion 39a Large diameter portion 40 Branch passage portion 41 Plug member 42, 43 In-wall passage portion 44 Communication hole

Claims (5)

a collective exhaust port including a plurality of exhaust ports respectively connected to a plurality of cylinders; and an exhaust collecting portion configured to collect the plurality of exhaust ports;
a cooling water passage configured to flow cooling water in a row direction in which each of the plurality of cylinders is arranged side by side;
The cooling water passage is
an upper passage provided above the collective exhaust port to which cooling water is supplied from one side in the row direction and discharged to the other side ;
a lower passage provided below the collective exhaust port facing the upper passage, to which cooling water is supplied from one side in the row direction and discharged to the other side ;
The lower passage includes a port passage portion provided corresponding to the collective exhaust port, and a sub-passage portion extending along the row direction of the cylinders from the downstream side , which is the other side of the port passage portion. ,
having an outlet passage portion extending in the row direction of the cylinders on the downstream side, which is the other side of the upper passage,
A cylinder head for a multi-cylinder engine, wherein the lower passage communicates with the outlet passage through the sub passage. The sub-passage portion has a large-diameter portion having a larger diameter than the diameter of the connection portion with the port passage portion,
2. The cylinder head according to claim 1, wherein said large diameter portion of said sub-passage is connected to said upper passage. The upper passage has a cylinder passage portion arranged corresponding to the plurality of cylinders arranged side by side, and a port passage portion arranged corresponding to the collective exhaust port,
3. The cylinder head according to claim 1, wherein said outlet passage portion is downstream of said cylinder passage portion. The upper passage has a branch passage extending from the outlet passage in a direction intersecting the row direction of the cylinders,
4. The cylinder head according to claim 3, wherein said sub passage portion is connected to said outlet passage portion via said branch passage portion. 5. A cylinder head according to any one of claims 1 to 4, wherein the sub-passage portion of the lower passage is formed by a skirting board on which cores forming the port passage portion of the lower passage are supported.

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