JP2000220451A - Cylinder head cooling structure for internal combustion engine - Google Patents

Abstract

(57) [Problem] To provide a cylinder head cooling structure of an internal combustion engine capable of efficiently cooling a high-temperature portion. SOLUTION: Cooling water flowing from a cooling water inflow section 32 is guided by a guide wall section 26, a flow path resistance section 32a, and the like, and is directed to a fourth cooling water path 10 in a cooling water path of a corresponding combustion chamber. Most amount flows. In this way, most of the cooling water surely flows between the exhaust port wall 18a and the fuel injection valve hole wall 4b. As a result, almost the center of the high-temperature portion can be cooled by the cooling water having a sufficient flow rate, and the high-temperature portion of the cylinder head can be efficiently cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to combustion by flowing cooling water from a cooling water inflow section to a cooling water outflow section through a cooling water path formed for each combustion chamber in a cylinder head of an internal combustion engine. The present invention relates to a cylinder head cooling structure for an internal combustion engine that cools a cylinder head heated from a chamber.

[0002]

2. Description of the Related Art In a cylinder head of an internal combustion engine such as a diesel engine or a gasoline engine, a portion corresponding to a central portion of a combustion chamber is particularly easily heated, and this portion becomes a high temperature portion. For this reason, it is necessary for the cooling structure of the cylinder head to efficiently cool the high-temperature portion.

[0003] Usually, in such a high-temperature portion, the walls forming the intake port and the exhaust port, the hole wall of the spark plug, the hole wall of the fuel injection valve, and the like are concentrated, and the cooling water path is greatly restricted. It becomes very narrow. For this reason, even if the cooling water simply flows from one end of the water jacket to the opposite side, the cooling water flows intensively in a portion where the flow path resistance is small, so that the flow rate in the high temperature portion becomes extremely small, and Efficient cooling of the part becomes difficult.

In order to allow as much cooling water as possible to flow to the high-temperature part, the inside of the water jacket of the cylinder head is divided by a partition wall for each combustion chamber, and the cooling water is directed from the center of the partition wall toward the center of the combustion chamber. (Japanese Patent Laid-Open Publication No. Hei 5-8696) has proposed a technique in which a protruding wall is formed to guide the flow direction.
No. 9).

[0005] In such a cylinder head, the cooling water supplied into the water jacket flows along the partition wall for each combustion chamber, and when the cooling water collides with the protruding wall, the flow of the cooling water is directed to the high-temperature portion. As a result, a large amount of cooling water flows even in high-temperature areas where the walls of the intake port and exhaust port, the hole wall of the ignition plug, and the hole wall of the fuel injection valve are concentrated, enabling efficient cooling. It is that.

[0006]

However, in the above-mentioned prior art, the flow direction of the cooling water in the water jacket is merely directed toward the high temperature portion. And the flow path cross-sectional area of the flow path sandwiched between the protruding walls cannot be said to be sufficiently small, and the flow rate of the cooling water in the high temperature part does not become high,
Further, the flow of the cooling water from the wall of the exhaust port to the wall of the hole cannot be said to be reliable depending on the flow path resistance, and the cooling water is returned from the protruding wall to the partition wall side. Therefore, it cannot be said that the cooling water has not been sufficiently flown to the high-temperature portion and the cooling has not been performed efficiently.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cylinder head cooling structure for an internal combustion engine that can efficiently cool a high-temperature portion.

[0008]

According to a first aspect of the present invention, there is provided a cylinder head cooling structure for an internal combustion engine, wherein cooling water flows from a cooling water inflow section to a cooling water path formed for each combustion chamber in the cylinder head of the internal combustion engine. By flowing cooling water toward the part,
A cylinder head cooling structure for an internal combustion engine that cools the inside of a cylinder head heated from a combustion chamber, wherein the cooling water path is configured to supply a high-temperature part in the cylinder head with cooling water supplied from the cooling water inflow part. It is characterized by having a high temperature part cooling path through which a main amount or the entire amount flows.

The cooling water path for each combustion chamber in the cylinder head has a high temperature section cooling path. The high-temperature part cooling path is for flowing a main amount or the entire amount of the cooling water supplied from the cooling water inflow part to the high-temperature part in the cylinder head.

As described above, the cooling water flowing through the cooling water path surely flows through the high temperature section due to the existence of the high temperature section cooling path. In addition, the main amount or the entire amount of the cooling water flows into the high temperature part cooling path. Thus, the high-temperature portion can be reliably cooled by the cooling water having a sufficient flow rate.

According to a second aspect of the present invention, there is provided a cylinder head cooling structure for an internal combustion engine according to the first aspect, wherein the high-temperature portion cooling path includes an exhaust port wall forming an exhaust port;
It is characterized in that it is formed between the exhaust port wall and a central wall provided at the center of the combustion chamber.

The space between the exhaust port wall and the central wall is a main portion of the high temperature section, and this position can be cooled by a sufficient flow of cooling water flowing through the high temperature section cooling path. In addition to the effects of the first aspect, more efficient cooling of the high-temperature portion can be performed.

According to a third aspect of the present invention, there is provided a cylinder head cooling structure according to the second aspect, wherein the central wall is a hole wall of a fuel injection valve, a wall of a sub-combustion chamber, or a spark plug. Characterized in that it is a wall portion of the hall.

The center wall includes a hole wall of a fuel injection valve or a wall of a sub-combustion chamber in the case of a diesel engine, and a hole wall of a spark plug in the case of a gasoline engine.

By providing the high temperature section cooling path between the central wall section and the exhaust port wall section, the function and effect of claim 2 can be obtained. According to a fourth aspect of the present invention, in the cylinder head cooling structure for an internal combustion engine, two or more exhaust ports are provided for one combustion chamber, and the high-temperature part cooling path is provided for the one or more combustion chambers. A cooling water flow path is formed between the exhaust port wall and the central wall in one direction from one end to the other end of the arranged exhaust port walls.

When two or more exhaust ports are provided in one combustion chamber, the cooling port is formed as a path through which cooling water flows in one direction from one end to the other end of the exhaust port wall where the high-temperature section cooling paths are arranged. The cooling water can be reliably flowed between the exhaust port wall and the central wall, and in addition to the function and effect of the second or third aspect, more efficient cooling of the high-temperature portion can be performed.

According to a fifth aspect of the present invention, there is provided a cylinder head cooling structure for an internal combustion engine, wherein the exhaust port wall is formed integrally with all the exhaust ports. A drilled passage is formed between the passages, and cooling water flows from the drilled passage toward the central wall.

Since all the exhaust port walls are integrally formed as described above, the high-temperature portion cooling path can reliably flow cooling water in one direction from one end to the other end of the arranged exhaust port walls. It will be formed as a path. Furthermore, since the drilled passage allows the cooling water to flow toward the central wall, the high-temperature section cooling path can obtain a more sufficient flow rate, and a large amount of high-speed cooling water flows on the central wall surface. Become. Therefore, in addition to the operation and effect of the fourth aspect, the cooling water from the drilled passage enables more efficient cooling of the high-temperature portion, particularly, the central wall portion.

According to a sixth aspect of the present invention, there is provided a cylinder head cooling structure for an internal combustion engine, wherein the exhaust port wall is formed independently at each exhaust port. A gap through which the cooling water can flow is formed between the walls.

Since the exhaust port wall is independent for each exhaust port as described above, the cooling area of the exhaust port wall is increased in addition to the effect of the fourth aspect, and exhaust is more efficiently performed. The port wall can be cooled.

According to a seventh aspect of the present invention, there is provided a cylinder head cooling structure for an internal combustion engine according to any one of the second to sixth aspects, wherein the cooling water inflow portion is provided near the exhaust port wall. The water outlet is provided near an intake port wall forming an intake port.

By providing the cooling water inflow section and the cooling water outflow section of the cooling water path in this way, a sufficient flow of cooling water can flow through the high temperature section cooling path existing in the cooling water path. In addition, the cooling water flows from the exhaust port wall side to the intake port wall side, and can be cooled. Accordingly, in addition to the function and effect of any of claims 2 to 6, the entire exhaust port wall and the entire intake port wall are also efficiently cooled.

According to an eighth aspect of the present invention, in the cylinder head cooling structure for an internal combustion engine, the cooling water inflow is provided by a guide wall extending from the intake port wall to the vicinity of the cooling water inflow portion. A main amount or the entire amount of the cooling water flowing from the section into the cooling water path is introduced into the high temperature section cooling path.

As described above, since the guide wall extends from the intake port wall to the vicinity of the cooling water inflow section, the cooling water path is formed so that the main amount or the entire amount of the cooling water can be introduced into the high temperature section cooling path. It is possible to cool the high-temperature portion more efficiently in addition to the effect of the seventh aspect.

According to a ninth aspect of the present invention, there is provided a cylinder head cooling structure for an internal combustion engine, wherein the intake port wall and the central wall are integrated with each other.

By integrating the intake port wall and the center wall in this way, the guide wall described in claim 8 allows the cooling water to flow particularly between the exhaust port wall and the center wall. It will be concentrated and flow. Therefore, in addition to the effect of the eighth aspect, the high-temperature portion can be cooled more efficiently.

According to a tenth aspect of the present invention, in the cylinder head cooling structure according to the seventh aspect, the cooling water path is divided into two paths on both sides of the exhaust port wall. And a downstream path connected to the upstream path and surrounding the intake port wall, and one of the upstream paths is between the exhaust port wall and the central wall. And a high-temperature section cooling path passing through the upstream path, wherein the other path of the upstream path has a higher flow path resistance than the one path.

Although the upstream path of the cooling water path is divided into two paths, the path that does not include the high-temperature section cooling path in the upstream path is compared with the path that includes the high-temperature section cooling path. Since the resistance is increased, the main amount of the cooling water flows through the high-temperature part cooling path, and the operation and effect according to any one of claims 7 to 9 is produced.

Further, almost half of the exhaust port wall is cooled even by a path that does not include the high-temperature section cooling path through which a small amount of cooling water flows, so that the exhaust port wall, which tends to become hot, is more efficiently cooled. be able to.

The cylinder head cooling structure for an internal combustion engine according to the eleventh aspect is different from the configuration according to the tenth aspect in that the difference in the flow path resistance between the two paths in the upstream path is the difference in the flow path cross-sectional area of the paths. Characterized by the following.

As described above, in addition to the effect of the tenth aspect, the difference in flow path resistance between the two paths can be easily provided due to the difference in the cross-sectional area of the flow path, thereby suppressing the manufacturing cost of the cylinder head. Can be.

According to a twelfth aspect of the present invention, in the cylinder head cooling structure according to the eleventh aspect, a rib formed on a bolt boss of the cylinder head projects into the other of the upstream paths. Thereby, the flow path resistance of the passage is increased and the cylinder head is also reinforced.

Since the ribs also reinforcing the cylinder head are protruded into the path to increase the flow path resistance of the path, in addition to the function and effect of claim 11, an unnecessary increase in the weight of the cylinder head is reduced. Can be suppressed.

According to a thirteenth aspect of the present invention, in the cylinder head cooling structure of the internal combustion engine, a peripheral wall of a drilled passage for introducing cooling water into the cooling water path is provided within the upstream path. By protruding into the other path, the flow path resistance of the path is increased.

As described above, the peripheral wall of the drilled passage may be used to increase the flow path resistance. In addition to the effect of the eleventh aspect, since the peripheral wall of the drilled passage is also used, the wasted weight of the cylinder head is reduced. The increase can be suppressed.

According to a fourteenth aspect of the present invention, there is provided a cylinder head cooling structure according to any one of the first to thirteenth aspects, further comprising a cooling water collecting passage extending vertically through all the combustion chambers in the cylinder head. The cooling water outlet of the cooling water path is connected to the cooling water collecting path.

The cooling water that has flowed out of the cooling water outflow portion flows through the cooling water collecting passage that runs through all the combustion chambers in the cylinder head to further cool the cylinder head. In addition to the effects of any one of (1) to (13), the cooling efficiency of the entire cylinder head is further improved.

According to a fifteenth aspect of the present invention, in the cylinder head cooling structure according to the fourteenth aspect, the cooling water collecting passage is arranged so as to pass outside an intake port wall forming an intake port. It is characterized by having been done.

Since the cooling water collecting passage passes outside the intake port wall as described above, in addition to the function and effect of claim 14, heat from the combustion chamber outside the intake port wall can be efficiently removed. By absorbing, the cooling efficiency of the entire cylinder head can be improved.

According to a sixteenth aspect of the present invention, in the cylinder head cooling structure according to any one of the first to fifteenth aspects, the cooling water path is formed in a plurality of layers in the cylinder head of the internal combustion engine. The cooling water path is a lowermost layer of the cooling water path.

In the case where the cooling water path is divided into a plurality of layers in the cylinder head as described above, by applying the configuration according to any one of claims 1 to 15 to the lowermost cooling water path, In addition to the functions and effects of any one of the first to fifteenth aspects, the cooling efficiency of the high-temperature portion and the entire cylinder head is further improved.

[0042]

[First Embodiment] FIG. 1 is a longitudinal sectional view (a sectional view taken along line BB in FIG. 2) of a cylinder head 2 in a diesel engine to which the above-described invention is applied. FIG. 2 is a horizontal sectional view of the cylinder head 2 (a sectional view taken along line AA in FIG. 1).

The cylinder head 2 is integrally formed as a casting of an aluminum alloy. The present diesel engine has a structure having four cylinders. However, since the structure is basically the same for each cylinder, a partial structure of the cylinder head 2 corresponding to one cylinder is mainly shown.

In the cylinder head 2, a fuel injection valve housing hole 4 for housing a fuel injection valve (not shown) is formed in the center in the vertical direction. Around the fuel injection valve housing hole 4, cooling water paths 5, 7, 8, 9, 10 constituting a water jacket are formed. Of these, the cooling water path 10 corresponds to a high temperature section cooling path.

The cylinder head 2 is provided with a two-layer water jacket, and the cooling water paths 5, 7 correspond to the upper layer, and the cooling water paths 8, 9, 10 correspond to the lower layer. In the cross-sectional view of FIG. 1, a portion 7 a in which the upper-layer cooling water path 7 projects to the position of the lower-layer cooling water path 8 is shown. Lower cooling water paths 8 to 10 and upper cooling water paths 5,
7 is separated. FIG. 2 shows the configuration of the lower cooling water paths 8 to 10.

In these lower cooling water paths 8 to 10,
Cooling water is supplied directly from a cylinder block (not shown) or via a drilled passage 12. At the height positions of the lower cooling water paths 8 to 10, the fuel injection valve hole wall 4b (corresponding to the central wall portion) forming the nozzle hole 4a at the tip of the fuel injection valve housing hole 4 is shown in FIG. As shown, the two intake ports 16 are formed integrally with the intake port wall 16a. In these wall portions 4b and 16a, glow plug storage holes 14 are provided.
Is formed.

Independently of the above-mentioned walls 4b and 16a,
Exhaust port wall 1 for providing two exhaust ports 18
8a are integrally formed. This exhaust port wall 18
A drilled passage 12 extends through the space between the two exhaust ports 18 to form an opening 12 a for the cooling water passage 10. The opening 12a is directed to the fuel injection valve hole wall 4b and the cooling water path 1
0 is inclined slightly obliquely in the downstream direction (upward in FIG. 2).

The four bolt bosses 2 are arranged outside the combustion chamber region so as to surround the above-mentioned walls 4b, 16a and 18a.
0, 21, 22, and 23 are provided. The guide wall 26 extends from the intake port wall 16a and is connected to one of the bolt bosses 22 on the exhaust port 18 side. Further, the other bolt boss 20 on the exhaust port 18 side is connected to the induction port wall 17a forming the intake port 17 belonging to the combustion chamber region (adjacent in FIG. 2) of the adjacent cylinder. The part 27 extends and connects. Due to the guide walls 26 and 27, the configuration of the combustion chamber region at the center in the drawing is separated from the same configuration in the other combustion chamber regions of the adjacent cylinders except for some paths.

In the vicinity of the bolt boss 22 to which the guide wall portion 26 extends and is connected, and outside the combustion chamber region (adjacent downward in FIG. 2) of the adjacent cylinder, the cooling water inflow portion 32
Is formed, and cooling water is supplied to the cooling water inflow portion 32 from the cylinder block side. Outside the combustion chamber region shown in the center of the figure, there is a cooling water inflow portion 33 at a similar position, but the main supply of cooling water to its own combustion chamber region is as follows.
Cooling water inlet 3 existing outside the combustion chamber region of the adjacent cylinder
From two.

Note that the cooling water outflow portion 36 is
Are set between the unconnected side (upper side in FIG. 2) intake port wall 16a and the intake port wall 17a in the combustion chamber region of the adjacent cylinder.

The cooling water path from the cooling water inlet 32 to the cooling water outlet 36 is as follows. That is, the cooling water that has flowed into the cylinder head 2 from the cooling water inflow portion 32 is connected to the bolt boss 22 on the exhaust port 18 side and the exhaust port 1.
It flows through the first cooling water path 40 between the cylinder head peripheral wall 38 on the eighth side and enters the adjacent combustion chamber region.

Here, the cooling water inflow section 33 (the same applies to the cooling water inflow section 32) hardly supplies cooling water to the cooling water path in the combustion chamber region of the same cylinder. this is,
At the portion indicated by cross-hatching on the combustion chamber region side with respect to the cooling water inflow portion 33, the upper portion is held down by the exhaust port wall portion 18a, and is surrounded by the cooling water passages 9, 46 having a small flow path cross-sectional area. This is because the passage resistance portion 33a (the passage resistance portion 32a in the cooling water inflow portion 32) has a high passage resistance so that the cooling water flows into the combustion chamber region of the same cylinder (the other cross-hatching is also similar to the passage passage). Resistance part). Thus, the first cooling water path 40 communicating with the combustion chamber region of the adjacent cylinder has a smaller flow path resistance than the flow path resistance part 32a. For this reason, most of the cooling water flows into the combustion chamber region of the adjacent cylinder than the same combustion chamber region.

Most of the cooling water flowing from the first cooling water path 40 flows from the first cooling water path 40 because the cooling water hardly flows into the second cooling water path 9 due to the presence of the flow path resistance portion 33a. The water flows into the third cooling water path 42 between the exhaust port wall 18a and the guide wall 26. Subsequently, the fluid flows into the fourth cooling water path 10 that is continuous with the third cooling water path 42.

Due to the presence of the flow path resistance portion 33a, the fifth connection between the intake port wall 16a and the guide wall 27 extending from the intake port wall 17a in the adjacent combustion chamber region.
It flows into the cooling water path 44. The fifth cooling water path 44
The cooling water slightly flows from the cooling water inlet 33 through the sixth cooling water path 46 between the exhaust port wall 18a, the bolt boss 20 and the guide wall 27.

The cooling water collecting passage 8 formed between the cylinder head peripheral wall 48 on the intake port 16 side and the intake port wall 16a from the fifth cooling water passage 44 via the cooling water outflow portion 36. Flow into The cooling water collecting passage 8 guides cooling water to a discharge port (not shown) provided at one end of the cylinder head 2 through the inside of the cylinder head 2.

As described above, most of the cooling water flowing from the cooling water inflow portion 32 is discharged from the exhaust port wall portion 18.
a and the fourth cooling water passage 10 formed between the exhaust port wall 18a and the fuel injection valve hole wall 4b located at the center of the combustion chamber with respect to the exhaust port wall 18a. Further, the fourth cooling water path 10 has a drilled passage 12 at the center thereof.
Cooling water flows in from. In addition, since the opening 12a of the drilled passage 12 is inclined to the downstream side of the fourth cooling water path 10, the flow of the cooling water in the fourth cooling water path 10 is made stronger. For this reason, a large amount of cooling water flows into the fourth cooling water path 10.

The exhaust port wall 18a where the fourth cooling water path 10 is formed and the fuel injection valve hole wall 4b are formed.
Is substantially the center of a high-temperature portion that is heated from the combustion chamber and becomes particularly high in temperature.

According to the first embodiment described above, the following effects can be obtained. (I). Most of the cooling water flowing from the cooling water inflow portion 32 flows into the fourth cooling water passage 10 in the cooling water passage of the corresponding combustion chamber. In this way, most of the cooling water reliably flows between the exhaust port wall 18a and the fuel injection valve hole wall 4b due to the presence of the fourth cooling water path 10. As a result, the center of the high-temperature portion can be reliably cooled by the cooling water having a sufficient flow rate, and the high-temperature portion of the cylinder head 2 can be efficiently cooled.

(B). The cylinder head 2 according to the first embodiment is a cylinder head of a four-valve (two intake valves and two exhaust valves) diesel engine.
8a are provided in two rows. Fourth cooling water path 1
0 denotes the exhaust port wall 18a on one end of the arranged exhaust port wall 18a from the exhaust port wall 18a on the other end.
It is formed as a path through which cooling water flows in one direction. Therefore, it is possible to reliably supply the cooling water between the exhaust port wall 18a and the fuel injection valve hole wall 4b, and it is possible to cool the high-temperature portion more efficiently.

(C). Further, in the first embodiment, the two exhaust port walls 18a are formed integrally, and further, a drilled passage 12 is formed between the exhaust ports 18,
Cooling water also flows from the drilled passage 12 toward the fuel injection valve hole wall 4b. Since all of the plurality of exhaust port walls 18a are integrally formed in this manner, the fourth cooling water path 10 cools in one direction from one end of the arranged exhaust port walls 18a to the other end. It will be formed as a reliable path through which water flows. Further, the drilled passage 12 is provided on the fuel injection valve hole wall 4b.
Cooling water flows toward the fourth cooling water path 10
Thus, a more sufficient flow rate can be obtained, and a large amount of cooling water having a high flow velocity also flows on the surface of the fuel injection valve hole wall 4b. Therefore, the drilled passage 12
The cooling water from the above makes it possible to cool the high-temperature portion more efficiently and to cool the fuel injection valve hole wall 4b more efficiently.

(D). The cooling water inflow portion 33 is provided on one end side of the exhaust port wall portion 18a, and the cooling water outflow portion 36 is provided on one end side of a diagonal intake port wall portion 16a centered on the fuel injection valve hole wall 4b. . This allows a sufficient flow of cooling water to flow through the fourth cooling water path 10, and allows the cooling water to flow from the exhaust port wall 18a to the intake port wall 16a for cooling. Thus, the exhaust port wall 18a and the intake port wall 16a can also be efficiently cooled.

(E). The guide wall portion 26 is formed from the intake port wall portion 16a to the bolt boss 22 near the cooling water inflow portion 32. As described above, most of the cooling water can be reliably introduced into the fourth cooling water path 10 without leaking the cooling water by the guide wall portion 26, and the high-temperature portion can be cooled more efficiently.

(F). The intake port wall 16a and the fuel injection valve hole wall 4b are formed integrally. In this case, the cooling water flows intensively between the exhaust port wall 18a and the fuel injection valve hole wall 4b by the guide wall 26. Therefore, the high-temperature portion can be cooled more efficiently.

(G). The cooling water path around the exhaust port wall 18a includes a third cooling water path 42 and a fourth cooling water path.
In addition to the path composed of the cooling water path 10, the second cooling water path 9
And a path composed of a sixth cooling water path 46. Of these, the path composed of the second cooling water path 9 and the sixth cooling water path 46 has a flow rate smaller than the path composed of the third cooling water path 42 and the fourth cooling water path 10 due to the presence of the flow path resistance portion 33a. Road resistance has been increased. Therefore, the main amount of the cooling water flows through the third cooling water path 42 and the fourth cooling water path 10, but the second cooling water path 9 and the sixth cooling water path 4
Even through the path composed of 6, almost half of the exhaust port wall 18a is cooled by the flow of a small amount of cooling water. Therefore, it is possible to more efficiently cool the exhaust port wall portion 18a, which easily becomes high in temperature.

(H). Further, a path composed of the third cooling water path 42 and the fourth cooling water path 10 and a second cooling water path 9
The difference between the flow path resistance and the path formed by the sixth cooling water path 46 is formed by the difference in the flow path cross-sectional area of the path. Such adjustment of the cross-sectional area of the flow passage is performed by the cylinder head 2.
Can be easily realized by adjusting the thickness and diameter of the core at the time of casting. Therefore, the manufacturing cost of the cylinder head 2 can be reduced.

(I). In addition, the passage resistance portion 33a for adjusting the passage cross-sectional area has a drilled passage 1 under the passage resistance portion 33a.
2 has passed. That is, the flow path resistance part 33a utilizes the peripheral wall of the drilled passage 12. For this reason, even if the flow path resistance portion 33a is provided, since the peripheral wall of the drilled passage 12 is also used, the cylinder head 2
Wasteful weight increase can be suppressed.

(Nu). The cooling water flowing out of the cooling water outflow portion 36 is carried downstream along with the cooling water in the other combustion chamber regions in a cooling water collecting passage 8 which runs through the entire cylinder head 2 in the entire combustion chamber. Since the cylinder head 2 is also cooled by the cooling water collecting passage 8, the cooling efficiency of the entire cylinder head 2 is further improved.

(L). Further, since the cooling water collecting passage 8 is disposed so as to pass outside the intake port wall 16a, it efficiently absorbs heat from the combustion chamber outside the intake port wall 16a, and The overall cooling efficiency can be improved.

(ヲ). As described above, the fourth cooling water path 10
The configuration in which the high-temperature portion can be efficiently cooled is realized as the configuration of the lowermost layer cooling water path among the cooling water paths formed in a plurality of layers (here, two layers) in the cylinder head 2. Therefore, the cooling efficiency of the high-temperature portion and the entire cylinder head 2 is further improved.

[Second Embodiment] The second embodiment is different from the first embodiment in that the two exhaust ports 118 are independent at the height position of the lower cooling water path as shown in FIG. This is a point formed by the exhaust port wall portion 118a, and a related point is that no drilled passage is provided between the exhaust ports 118. Unless otherwise specified, in the second embodiment, components having the same functions as those of the first embodiment are denoted by reference numerals obtained by adding “100” to the reference numerals assigned to the corresponding configurations of the first embodiment. Is shown.

With such a configuration, the cooling water inlet 13
The cooling water flowing in from the second cooling water path 140, the third cooling water path 142, the fourth cooling water path 110 (corresponding to the high-temperature part cooling path), and the fifth cooling water path are the same as in the first embodiment. Through the cooling water path 144 and the cooling water outflow portion 136,
There is a cooling water path leading to the cooling water collecting path 108. Then, the first cooling water path 140 passes through the second cooling water path 109 and the sixth cooling water path 146 to the fifth cooling water path 144.
There is a cooling water path that joins the cooling water.

Further, in the second embodiment, the gap between the two exhaust port walls 118a is used as the second cooling water passage 109.
Cooling water path 1 that communicates with the fourth cooling water path 110
There are 50.

According to the second embodiment described above, the following effects can be obtained. (I). (A), (b), and (b) according to the first embodiment.
The effects of (d) to (h) and (nu) to (ヲ) are produced.

(B). Since the exhaust port wall 118a is independent for each exhaust port 118, the exhaust port wall 1
The seventh cooling water path 150 is formed as a gap 18a, and the cooling water can flow. Thus, the cooling area of the exhaust port wall 118a increases, and the exhaust port wall 118a can be cooled more efficiently.

[Third Embodiment] The third embodiment differs from the first embodiment in that, as shown in FIG. 4, the guiding wall portion 226 is on the opposite side to the first embodiment (FIG. 4). (Upper side in the figure) extending from the intake port wall portion 216a to the bolt boss 220. Further, bolt bosses 220 and 222
Is that the cooling water path does not exist between the bolt bosses 220 and 222 and the cylinder head peripheral wall portion 238 integrated with the cylinder head peripheral wall portion 238 on the exhaust port 218 side. In addition, unless otherwise specified, in the third embodiment, components having the same functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment.
00 ”.

As a result, the upper bolt boss 2
Cooling water is introduced from a cooling water inflow portion 233 closer to 20 into a cooling water path in the combustion chamber region of the same cylinder. Most of the cooling water from the cooling water inflow portion 233 flows through the first cooling water passage 246, the second cooling water passage 210 (corresponding to the high-temperature portion cooling passage), the third cooling water passage 244, and the cooling water outflow portion 236. After that, the cooling water collecting passage 208 is reached. Also, a small amount of cooling water joins the third cooling water path 244 from the cooling water inflow section 233 via the fourth cooling water path 209 and the fifth cooling water path 242 for the flow path resistance section 233a.

As in the first embodiment, cooling water joins from drilled passage 212 to second cooling water passage 210. According to the third embodiment described above,
The following effects can be obtained.

(A). (B) according to the first embodiment.
~ (ヲ) effect is produced. (B). Cooling water outflow section 2 which flows in from cooling water inflow section 233
Since the cooling water flowing out of 36 passes through an independent path for each combustion chamber region, each high-temperature portion can be cooled reliably and uniformly without any difference between the combustion chamber regions. Therefore, the cooling efficiency of the entire cylinder head can be further improved.

[Fourth Embodiment] The fourth embodiment is different from the third embodiment in that the two exhaust port walls 318a are independent as shown in FIGS.
The sixth cooling water passage 350 is formed as a gap between the two exhaust port walls 318a.

Further, in the fourth cooling water path 309, a substantially triangular rib is formed from the bolt boss 352 on the exhaust port wall 318 a side (the lower side in FIGS. 5 and 6) away from the cooling water inflow section 333. 354 project. This rib 35
4 is formed at the base of the bolt boss 352 in a state of being connected to the bottom surface of the fourth cooling water path 309. This is different from the third embodiment in that the fourth cooling water path 309 is largely closed with a small flow path left.

FIG. 5 is a cross-sectional view taken at the same height as FIGS. 2 to 4 of each embodiment described above.
Is a cross-sectional view cut slightly above it. Unless otherwise specified, in the fourth embodiment, components having the same functions as those of the third embodiment are denoted by reference numerals obtained by adding “100” to the reference numerals assigned to the corresponding configurations of the third embodiment. Is shown.

With such a configuration, the cooling water inflow portion 33
The cooling water flowing in from the third cooling water path 346, the second cooling water path 310, the third cooling water path 344, and the cooling water outflow part 336 is the same as in the third embodiment. Flows to And the cooling water inflow section 333
And a fourth cooling water path 309, and a cooling water path merging from the fifth cooling water path 342 to the third cooling water path 344.

Further, in the fourth embodiment, the space between the two exhaust port walls 318a is used as the fourth cooling water passage 309.
Cooling water path 3 communicating with the second cooling water path 310 from
There are 50.

As a result, the upper bolt boss 3
Cooling water is introduced from the cooling water inflow section 333 closer to 20 to the cooling water path in the combustion chamber region of the same cylinder. Most of the cooling water from the cooling water inflow section 333 passes through the first cooling water path 346, the second cooling water path 310, the third cooling water path 344, and the cooling water outflow section 336 to the cooling water collecting path 308. Reach. Further, the flow path resistance portion 333a and the rib 3
Due to 54, a small amount of cooling water from the fifth cooling water path 342 joins the third cooling water path 344. Furthermore, rib 3
A larger amount of cooling water guided to the cooling water passage 54 than through the fifth cooling water passage 342 is supplied to the fourth cooling water passage 350 through the fourth cooling water passage 350.
The cooling water flows from the cooling water path 309 to the second cooling water path 310.

According to the fourth embodiment described above, the following effects can be obtained. (I). (B) and (B) according to the second embodiment.
Produces the effect of (B). The effect (b) of the third embodiment is obtained.

(C). By projecting the rib 354 that also serves as a reinforcement for the cylinder head into the fourth cooling water path 309, the flow path cross-sectional area is reduced in a part of the fourth cooling water path 309 to increase the flow path resistance. Therefore, the rigidity of the lower surface of the cylinder head can be improved without significantly increasing the weight of the cylinder head.

[Other Embodiments] In the above embodiments, an example of a diesel engine has been described, but the present invention may be applied to a gasoline engine. When applied to a gasoline engine, a spark plug hole is formed at the position of the fuel injection valve housing hole, and there is no glow plug housing hole.

In the case of a diesel engine, a structure in which an auxiliary combustion chamber is provided instead of the fuel injection valve housing hole may be used. In the first embodiment, the cooling water is taken in from the cooling water inflow portion existing in the combustion chamber region of the adjacent cylinder.
By changing the distribution of the flow path resistance of the flow path resistance section around the cooling water inflow section, the cooling water may be taken in from the cooling water inflow section existing in the combustion chamber region of the same cylinder.

Although the embodiments of the present invention have been described above, the embodiments of the present invention include the following various technical items in addition to the technical items described in the claims. It should be noted that it has.

(1) The cooling water inflow portion and the cooling water outflow portion are located at opposite positions with respect to the high temperature portion in each combustion chamber.
A cylinder head cooling structure for an internal combustion engine according to any one of the above.

(2) The cylinder head cooling structure for an internal combustion engine according to any one of claims 4 to 6, wherein the cooling water outflow portion substantially exists on a center line in the arrangement direction of the intake ports.

(3) A surrounding wall having the central wall as a part is formed around the exhaust port wall with a cooling water passage therebetween, and the cooling water flows into the surrounding wall into the surrounding wall. Cooling water, which has one inlet and one outlet which flows out of the surrounding wall, and which does not include the high-temperature part cooling path among the two cooling water paths divided by the positions of the inlet and the outlet. The cylinder of an internal combustion engine according to any one of claims 2 to 7, wherein the flow path resistance of the path portion is set to be larger than the flow path resistance of the cooling water path portion including the high temperature portion cooling path. Head cooling structure.

Here, as an example of the third embodiment, the fuel injection valve hole wall 204b, the intake port wall 216a,
The bolt bosses 220 and 222, the guide walls 226 and 227, and the cylinder head peripheral wall 238 correspond to the surrounding wall in (3). In the fourth embodiment, the fuel injection valve hole wall 304b, the intake port wall 316a, the bolt bosses 320 and 322, the guide walls 326 and 327, and the cylinder head peripheral wall 338 correspond to the surrounding wall in (3).

(4) A surrounding wall having the central wall as a part is formed around the exhaust port wall with a cooling water passage therebetween, and the cooling water flows into the surrounding wall into the surrounding wall. A plurality of inlets, and one outlet for flowing out of the surrounding wall, wherein the cooling water path is divided into two by the position of the inlet and the outlet having the smallest flow path resistance among the inlets. 3. The flow path resistance of the cooling water path portion not including the high temperature part cooling path is set to be larger than the flow path resistance of the cooling water path part including the high temperature part cooling path. 8. The cylinder head cooling structure for an internal combustion engine according to any one of claims 7 to 7.

Here, for example, in the first embodiment, the fuel injection valve hole wall 4b, the intake port wall 16a, the bolt bosses 20, 22, the guide walls 26, 27, and the cylinder head peripheral wall 38 are surrounded by (4). Equivalent to a wall. In the second embodiment, the fuel injection valve hole wall 104b,
Intake port wall 116a, bolt bosses 120 and 122,
Guide walls 126 and 127 and cylinder head peripheral wall 1
38 corresponds to the surrounding wall in (4).

[0096]

According to the first aspect of the present invention, the cooling water path for each combustion chamber has a high temperature section cooling path. The high-temperature part cooling path is for flowing a main amount or the entire amount of the cooling water supplied from the cooling water inflow part to the high-temperature part in the cylinder head. As described above, the cooling water flowing through the cooling water path surely flows through the high temperature section due to the presence of the high temperature section cooling path. In addition, the main amount or the entire amount of the cooling water flows into the high temperature part cooling path. Thus, the high-temperature portion can be reliably cooled by the cooling water having a sufficient flow rate.

According to a second aspect of the invention, there is provided a cylinder head cooling structure for an internal combustion engine, wherein the high-temperature portion cooling path includes an exhaust port wall forming an exhaust port and the exhaust port wall. And a central wall portion provided at the center of the combustion chamber rather than the central portion. The portion between the exhaust port wall and the central wall is a main portion of the high temperature section, and this position can be cooled by a sufficient flow of cooling water flowing through the high temperature section cooling path. In addition to the effect, more efficient cooling of the high-temperature portion is enabled.

According to a third aspect of the present invention, in the cylinder head cooling structure for an internal combustion engine according to the second aspect, the center wall is a hole wall of a fuel injection valve, a wall of a sub-combustion chamber, or an ignition. It is the wall of the plug. By providing the high-temperature section cooling path between the central wall section and the exhaust port wall section, the function and effect of claim 2 can be achieved.

According to a fourth aspect of the present invention, there is provided a cylinder head cooling structure for an internal combustion engine, wherein two or more exhaust ports are provided for one combustion chamber with respect to the configuration of the second or third aspect. The path is formed between the exhaust port wall and the central wall as a path through which cooling water flows in one direction from one end to the other end of the arranged exhaust port walls. When the high-temperature section cooling path is formed as a path in which cooling water flows in one direction from one end of the arranged exhaust port walls to the other end, cooling is reliably performed between the exhaust port walls and the central wall. Water can be flowed, and in addition to the effects of the second or third aspect, more efficient cooling of the high-temperature portion can be performed.

According to a fifth aspect of the present invention, in the cylinder head cooling structure for an internal combustion engine, the exhaust port wall is formed integrally with all the exhaust ports. A drilled passage is formed between the ports, and cooling water flows from the drilled passage toward the central wall. Since all the exhaust port walls are integrally formed in this way, the high temperature section cooling path is a reliable path through which cooling water flows in one direction from one end to the other end of the arranged exhaust port walls. Will be formed. Furthermore, since the drilled passage allows the cooling water to flow toward the central wall, the high-temperature section cooling path can obtain a more sufficient flow rate, and a large amount of high-speed cooling water flows on the central wall surface. Become. Therefore, in addition to the operation and effect of the fourth aspect, the cooling water from the drilled passage enables more efficient cooling of the high-temperature portion, particularly, the central wall portion.

According to a sixth aspect of the present invention, in the cylinder head cooling structure for an internal combustion engine, the exhaust port wall is formed independently at each exhaust port, so that each exhaust port wall is formed independently. A gap is formed between the port walls so that the cooling water can flow. Thus, claim 4
In addition to the function and effect, the cooling area of the exhaust port wall is increased, and the exhaust port wall can be more efficiently cooled.

According to a seventh aspect of the present invention, in the cylinder head cooling structure for an internal combustion engine, the cooling water inflow portion is provided near the exhaust port wall in the structure of the second aspect. The cooling water outflow portion is provided near the intake port wall forming the intake port. By providing the cooling water inflow section and the cooling water outflow section of the cooling water path in this manner, a sufficient flow of cooling water can flow through the high temperature section cooling path existing in the cooling water path, and furthermore, the exhaust port Cooling water flows from the wall side to the intake port wall side and can be cooled. Accordingly, in addition to the function and effect of any of claims 2 to 6, the entire exhaust port wall and the entire intake port wall are also efficiently cooled.

In the cylinder head cooling structure according to the eighth aspect, in addition to the structure according to the seventh aspect, the guide wall extends from the intake port wall to the vicinity of the cooling water inflow portion, and the main cooling water is provided. A large amount or the entire amount is introduced into the high temperature section cooling path. This makes it possible to cool the high-temperature portion more efficiently in addition to the effect of the seventh aspect.

In the cylinder head cooling structure for an internal combustion engine according to the ninth aspect, the intake port wall and the central wall are integrated with the structure according to the eighth aspect. As a result, the cooling water flows particularly concentrated between the exhaust port wall and the central wall by the guide wall described in claim 8. Therefore, in addition to the effect of the eighth aspect, the high-temperature portion can be cooled more efficiently.

According to a tenth aspect of the present invention, in the structure for cooling a cylinder head of an internal combustion engine, the cooling water path is divided into two paths on both sides of the exhaust port wall. An upstream path that divides around and a downstream path that is connected to the upstream path and circulates around the intake port wall, and one of the upstream paths is formed by the exhaust port wall and the central wall. Including a high-temperature section cooling path that passes between them, the other path of the upstream path has a higher flow path resistance than the one path. As described above, the upstream path of the cooling water path is divided into two paths, but the path that does not include the high-temperature section cooling path in the upstream path is compared with the path that includes the high-temperature section cooling path. Since the resistance is increased, the main amount of the cooling water flows through the high-temperature part cooling path, and the operation and effect according to any one of claims 7 to 9 is produced. Further, since almost half of the exhaust port wall is cooled even by a path that does not include the high-temperature section cooling path through which a small amount of cooling water flows, the exhaust port wall that easily becomes hot can be more efficiently cooled. .

In the cylinder head cooling structure for an internal combustion engine according to the eleventh aspect, the difference in the flow path resistance between the two paths in the upstream path is different from the configuration according to the tenth aspect.
It is formed by the difference in the flow path cross-sectional area of the path. In this way, in addition to the effects of the tenth aspect, a difference in flow path resistance between the two paths can be easily provided by a difference in flow path cross-sectional area, and the manufacturing cost of the cylinder head can be suppressed.

According to the cylinder head cooling structure of the twelfth aspect, the rib formed on the bolt boss of the cylinder head protrudes into the other of the upstream paths in the structure of the eleventh aspect. By doing
In addition to increasing the flow path resistance of the passage, it also serves to reinforce the cylinder head. Since the rib which also serves as a reinforcement for the cylinder head is protruded into the path to increase the flow path resistance of the path, in addition to the function and effect of claim 11, it is possible to suppress an unnecessary increase in the weight of the cylinder head. Can be.

According to a thirteenth aspect of the present invention, in the cylinder head cooling structure for an internal combustion engine, a peripheral wall of a drilled passage for introducing cooling water into the cooling water path is provided inside the upstream path. By projecting into the other path, the flow path resistance of the path is increased. As described above, the peripheral wall of the drilled passage may be used to increase the flow path resistance. In addition to the effects of the eleventh aspect, since the peripheral wall of the drilled passage is also used, unnecessary weight increase of the cylinder head is suppressed. can do.

According to a fourteenth aspect of the present invention, there is provided a cylinder head cooling structure according to any one of the first to thirteenth aspects, wherein a cooling water collecting passage extending longitudinally across all combustion chambers in the cylinder head is provided. The cooling water outlet is connected to the cooling water passage. The cooling water that has flowed out of the cooling water outlet in this way flows through the cooling water collecting passage that runs through all the combustion chambers in the cylinder head, thereby further cooling the cylinder head. In addition to any of the functions and effects, the cooling efficiency of the entire cylinder head is further improved.

In the cylinder head cooling structure according to a fifteenth aspect, the cooling water collecting passage passes outside the intake port wall forming the intake port. Are located. Since the cooling water collecting passage passes outside the intake port wall as described above, in addition to the function and effect of claim 14, heat from the combustion chamber outside the intake port wall is efficiently absorbed. ,
The cooling efficiency of the entire cylinder head can be improved.

[0111] In the cylinder head cooling structure of the sixteenth aspect, the cooling water path is formed in a plurality of layers in the cylinder head of the internal combustion engine in the structure of any one of the first to fifteenth aspects. This is the lowermost cooling water path of the cooling water paths. When the cooling water path is divided into a plurality of layers in the cylinder head as described above, the configuration according to any one of the above-described claims 1 to 15 is applied to the lowermost cooling water path. In addition to the effects of any one of (1) to (15), the cooling efficiency of the high-temperature portion and the entire cylinder head is further improved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a cylinder head of a diesel engine according to a first embodiment.

FIG. 2 is a horizontal sectional view of the cylinder head shown in FIG.

FIG. 3 is a horizontal sectional view of a cylinder head according to a second embodiment.

FIG. 4 is a horizontal sectional view of a cylinder head according to a third embodiment.

FIG. 5 is a horizontal sectional view of a cylinder head according to a fourth embodiment.

FIG. 6 is a horizontal cross-sectional view of a cylinder head at different heights according to a fourth embodiment.

[Explanation of symbols]

2 ... cylinder head, 4 ... fuel injection valve storage hole, 4a ... nozzle hole, 4b ... fuel injection valve hole wall, 5 ... upper layer cooling water path, 7 ... upper layer cooling water path, 7a ... cooling water path 7 projection Part, 8: cooling water collecting passage, 9: second cooling water passage, 10
... 4th cooling water path, 11 ... boundary wall, 12 ... drilled passage, 12a ... opening, 14 ... glow plug storage hole, 14a ... tip hole, 16 ... intake port, 16a ... intake port wall, 17 ... intake Port, 17a: intake port wall, 18: exhaust port, 18a: exhaust port wall, 2
0, 21, 22, 23: bolt boss, 26, 27: guide wall, 32: cooling water inflow, 32a: flow resistance, 3
DESCRIPTION OF SYMBOLS 3 ... Cooling water inflow part, 33a ... Flow path resistance part, 36 ... Cooling water outflow part, 38 ... Cylinder head peripheral wall part, 40 ... 1st cooling water path, 42 ... 3rd cooling water path, 44 ... 5th cooling water Path: 46: sixth cooling water path, 48: cylinder head peripheral wall, 108: cooling water collecting path, 109: second cooling water path
110: fourth cooling water path, 118: exhaust port, 118
a: exhaust port wall portion, 132: cooling water inflow portion, 136 ...
Cooling water outlet 140, first cooling water path 142, third cooling water path 144: fifth cooling water path 146: sixth
Cooling water path, 150: seventh cooling water path, 208: cooling water collecting path, 209: fourth cooling water path, 210: second cooling water path, 218: exhaust port, 218a: exhaust port wall, 220: bolt boss 226 ... guide wall part, 233 ...
Cooling water inflow section, 233a ... flow path resistance section, 236 ... cooling water outflow section, 238 ... cylinder head peripheral wall section, 242 ... fifth
Cooling water path, 244: third cooling water path, 246: first cooling water path, 308: cooling water collecting path, 309: fourth cooling water path, 310: second cooling water path, 318a: exhaust port wall section, 320: bolt boss, 333: cooling water inflow section, 3
33a: flow path resistance section, 336: cooling water outflow section, 342 ...
Fifth cooling water path, 344: third cooling water path, 346: first cooling water path, 350: sixth cooling water path, 352: bolt boss, 354: rib.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahisa Nagata 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Takanori Kawazu 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation ( 72) Inventor Tomoaki Suzuki 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Ryo Fujii 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Satoru Omoto Osaka F-1 term (reference) in Daihatsu Kogyo Co., Ltd. 1-1 Daihatsu-cho, Ikeda-shi, Fukuoka (Reference) 3G024 AA02 AA04 AA12 BA05 CA05 CA26 DA01 DA02 DA06 FA00 FA01 FA13 FA14 GA01 HA07

Claims (16)

[Claims] 1. A cylinder heated from a combustion chamber by flowing cooling water from a cooling water inflow section to a cooling water outflow section through a cooling water path formed for each combustion chamber in a cylinder head of an internal combustion engine. A cylinder head cooling structure for an internal combustion engine that cools the inside of a head, wherein the cooling water path is a
A cylinder head cooling structure for an internal combustion engine, comprising: a high temperature section cooling path through which a main amount or the entire amount of cooling water supplied from the cooling water inflow section flows. 2. The high-temperature section cooling path is formed between an exhaust port wall forming an exhaust port and a central wall provided at a center of the combustion chamber with respect to the exhaust port wall. The cylinder head cooling structure for an internal combustion engine according to claim 1, wherein: 3. The cylinder head cooling of an internal combustion engine according to claim 2, wherein the central wall is a hole wall of a fuel injection valve, a wall of a sub-combustion chamber, or a hole wall of a spark plug. Construction. 4. The exhaust port wall is provided two or more for one combustion chamber, and the high-temperature section cooling path is arranged between the exhaust port wall and the central wall. 3. A cooling water flow path is formed in one direction from one end to the other end.
4. A cylinder head cooling structure for an internal combustion engine according to claim 3. 5. The exhaust port wall is formed integrally with all exhaust ports, a drilled passage is formed between the exhaust ports, and the drilled passage extends from the drilled passage toward the central wall. The cylinder head cooling structure for an internal combustion engine according to claim 4, wherein cooling water is introduced. 6. The exhaust port wall portion is formed independently in each exhaust port, so that a gap through which cooling water can flow is formed between each exhaust port wall portion. 5. The cylinder head cooling structure for an internal combustion engine according to 4. 7. The cooling water inflow portion is provided near the exhaust port wall portion, and the cooling water outflow portion is provided near an intake port wall portion forming an intake port. 7. A cylinder head cooling structure for an internal combustion engine according to any one of claims 6 to 6. 8. A guide wall extending from the intake port wall to the vicinity of the cooling water inflow portion, the main or entire amount of the cooling water flowing from the cooling water inflow portion to the cooling water path is cooled by the high temperature portion cooling. The cylinder head cooling structure for an internal combustion engine according to claim 7, wherein the cylinder head cooling structure is introduced into a passage. 9. The cylinder head cooling structure for an internal combustion engine according to claim 8, wherein said intake port wall and said central wall are integrated. 10. The cooling water path has an upstream path that divides both sides of the exhaust port wall into two paths, and a downstream path that is connected to the upstream path and circulates around the intake port wall, One of the upstream paths includes a high-temperature section cooling path that passes between the exhaust port wall and the central wall, and the other of the upstream paths is compared with the one of the paths. The cylinder head cooling structure for an internal combustion engine according to any one of claims 7 to 9, wherein the flow passage resistance is increased. 11. The cylinder head cooling structure for an internal combustion engine according to claim 10, wherein a difference in flow path resistance between the two paths in the upstream path is formed by a difference in flow path cross-sectional area of the paths. . 12. A rib formed on a bolt boss of a cylinder head protrudes into the other of the upstream paths to increase the flow path resistance of the path and to reinforce the cylinder head. The cylinder head cooling structure for an internal combustion engine according to claim 11, wherein: 13. A flow path resistance of the passage is increased by projecting a peripheral wall of a drilled passage for introducing cooling water into the cooling water passage into another of the upstream passages. The cylinder head cooling structure for an internal combustion engine according to claim 11, wherein 14. A cooling water collecting passage which extends through all the combustion chambers in the cylinder head, and a cooling water outflow portion of the cooling water passage is connected to the cooling water collecting passage. Item 14. A cylinder head cooling structure for an internal combustion engine according to any one of Items 1 to 13. 15. The cylinder head cooling structure for an internal combustion engine according to claim 14, wherein the cooling water collecting passage is arranged to pass outside an intake port wall forming an intake port. 16. The cooling water path of a lowermost layer of the cooling water paths formed in a plurality of layers in a cylinder head of an internal combustion engine.
A cylinder head cooling structure for an internal combustion engine according to any one of the above.