JP2003056343A - Cylinder head cooling structure for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder head cooling structure for internal combustion engine capable of effectively cooling a central part of a cylinder head and suitably distributing the flow of cooling water for a whole of the cylinder head so as to improve cooling efficiency. SOLUTION: A cooling water path 5 is provided with an intake side cooling path 6 formed between an intake port wall part and a cylinder head peripheral wall part 4, an exhaust side cooling path 8 formed between an exhaust port wall part and the cylinder head peripheral wall part 4, and a central cooling path 7 formed between the intake port wall part and the exhaust port wall part. A communication path 34 is formed for communicating the central cooling path 7 and at least one of the intake side cooling path 6 and the exhaust side cooling path 8. A large flow part and a small flow part are formed on the central cooling path 7 through the communication path 34. A ratio of the large flow part in a central part 37 of the central cooling path is higher than a ratio of the large flow part in an end part of the central cooling path 7 other than the central part 37.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A cylinder head of an internal combustion engine is provided with a cooling water passage for cooling against heating from a combustion chamber. The cooling water passage is usually formed so that the cooling water can flow around the wall portion forming the intake port and the exhaust port. However, it is difficult to form a cooling water path with sufficient space between the intake port and the exhaust port because it is restricted by the arrangement of the intake port, exhaust port, fuel injection valve insertion port, etc. The temperature between the exhaust port and the exhaust port is particularly high. Therefore, even if the cooling water is made to flow from the inflow portion provided at one end of the cylinder head to the outflow portion provided at the other end, sufficient cooling is provided for the portion having a large flow resistance between the intake port and the exhaust port. Since water does not flow, it is difficult to efficiently cool between the ports, which are likely to reach a high temperature as described above.

Therefore, in order to allow as much cooling water as possible to flow between the intake port and the exhaust port to cool the ports that are likely to reach a high temperature, for example, in JP-A-5-86969, each combustion chamber is partitioned by a partition wall. Then, a partition wall in which a projecting wall for guiding the flow direction of the cooling water is formed from the middle of the partition wall toward the ports is disclosed.

[0004]

However, in the above description, the cooling water path is subdivided for each combustion chamber to guide the cooling water between the ports that are likely to reach a high temperature, and as a whole, excessive pressure loss is produced. There is a problem that the structure is likely to be tight, the structure is complicated, and as a result, supplying sufficient cooling water between the ports is likely to be impaired.

Further, in an internal combustion engine in which a plurality of cylinders are arranged, since there is little restraint in the vicinity of the end portion in the cylinder arrangement direction, thermal stress is less likely to occur than between the ports of the cylinders located in the portions other than the end portion, and it is not always necessary. It was also discovered until the completion of the present invention that it is not necessary to flow a large amount of cooling water. From this point of view, it is possible to appropriately distribute the flow rate of the cooling water as the entire cylinder head and further efficiently cool the central portion of the cylinder head in which a large thermal stress is generated. It was suggested.

In view of the above situation, the present invention provides
(EN) A cylinder head cooling structure for an internal combustion engine capable of efficiently cooling the central portion of the cylinder head, and further increasing cooling efficiency by appropriately distributing the flow rate of cooling water as a whole cylinder head.

[0007]

A cylinder head cooling structure for an internal combustion engine according to claim 1, which solves the above problems, has a cylinder of an internal combustion engine having a row of ports in which a plurality of intake valves and exhaust valves are respectively arranged. A cooling liquid path formed in the head, a cylinder head cooling structure for cooling the cylinder head heated from the combustion chamber by flowing the cooling liquid from the inflow portion to the outflow portion, wherein the cooling liquid path, An intake side cooling passage formed between the intake port wall portion forming the intake port row and the cylinder head peripheral wall portion, and formed between the exhaust port wall portion forming the exhaust port row and the cylinder head peripheral wall portion. An exhaust side cooling passage and a central cooling passage formed between the intake port wall portion and the exhaust port wall portion, wherein the central cooling passage and the intake side cooling passage or the exhaust gas are provided. A communication passage communicating with at least one of the cooling passages is formed, and a large flow rate portion and a small flow rate portion are formed in the central cooling passage through the communication passage, and a central portion of the central cooling passage is formed. Is formed so that the proportion occupied by the large flow rate portion is higher than the proportion occupied by the large flow rate portion at the end portion other than the central portion of the central cooling passage.

Here, the internal combustion engine provided with a port row in which a plurality of intake valves and exhaust valves are provided includes an internal combustion engine having either a single cylinder or multiple cylinders, and each cylinder has an intake valve. 2 valve type with one exhaust valve and one exhaust valve, or 2
It also includes multiple types such as four-valve types. Further, it is intended that the communication passage herein may be provided with only one or a plurality of passages. The large flow rate portion and the small flow rate portion have one communication passage in the central cooling passage.
In the case of one, it is determined corresponding to the upstream and downstream parts of the communication passage, and when there are multiple communication passages, the part sandwiched between adjacent communication passages and the most upstream communication passage of the communication passages. It is determined corresponding to each portion between the upstream end and the portion between the most downstream communication passage and the downstream end of the communication passages. In the case where there are a plurality of communication passages, if the cooling liquid flows into the central cooling passage from the communication passage on the upstream side of the portion sandwiched by the adjacent communication passages or the communication passage on the most downstream side of the communication passages, The part sandwiched between the adjacent communication passages that flowed in, or the part between the most downstream communication passage and the downstream end of the communication passages is defined as a large flow rate portion, and the upstream side of the portion sandwiched between the adjacent communication passages. If the cooling liquid does not flow into the central cooling passage from the communication passage of the above or the communication passage on the most downstream side of the communication passage, the portion sandwiched between the adjacent communication passages in which the cooling liquid does not flow or the communication passage The portion between the most downstream communication passage and the downstream end is the small flow rate portion. As for the portion between the upstream end of the central cooling passage and the adjacent communicating passage, if the cooling liquid flows into the central cooling passage from the communicating passage adjacent to the upstream end, the upstream end and the communicating passage are separated from each other. The portion between them is a small flow rate part, and if the cooling liquid does not flow into the central cooling passage from the communication passage, the portion between the upstream end and the communication passage is a large flow rate portion.

According to this structure, the communication passage for guiding the cooling liquid to the central portion is formed, and the flow rate of the cooling liquid in the central portion is increased with respect to the end portion via the communication passage. Therefore, the flow resistance between the intake port and the exhaust port is high, and the central portion of the cylinder head where thermal stress is likely to occur can be efficiently cooled. Further, according to this configuration, the end portion that does not necessarily need to flow a large amount of cooling liquid can be diverted to the intake side cooling passage or the exhaust side cooling passage through the communication passage. As a result, in the central cooling passage having a high flow resistance, it is possible to intensively cool the central portion where thermal stress is likely to occur. That is, the central portion is efficiently cooled, and the flow resistance is high, but the end portion that does not necessarily require a large amount of cooling liquid is diverted, and the pressure loss is reduced and the flow amount is increased as a whole cooling liquid path. be able to. Therefore, it is possible to provide a cylinder head cooling structure for an internal combustion engine that can improve cooling efficiency by appropriately distributing the flow rate of the cooling liquid as the entire cylinder head.

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 at least one of the communication passages is connected to the central cooling passage by the intake side cooling passage. By providing a flow rate regulating portion on the downstream side of the communication passage or the exhaust side cooling passage, the cooling liquid is caused to flow into the central portion via the communication passage, and the cooling liquid is provided downstream of the communication passage in the central portion. The large flow rate portion is formed on the side.

According to this structure, a simple structure in which the flow rate restricting portion is provided in the middle of the intake side cooling passage or the exhaust side cooling passage communicating with the central cooling passage, is the same as the invention described in claim 1. The effect can be obtained. Here, the flow rate control part is not particularly limited in shape, and is formed so that a part of the port wall part or the cylinder head peripheral wall part protrudes, or the wall part in the middle of the cooling path. It is intended to mean various things provided for narrowing the cooling passage or for blocking the cooling passage, such as those independently provided so as to narrow the passage.

According to a third aspect of the present invention, there is provided a cylinder head cooling structure for an internal combustion engine according to the first or second aspect, in which at least one of the intake side cooling passage and the exhaust side cooling passage is provided with a flow rate regulating portion. A large flow rate portion is formed in the central portion, and the communication passage is provided on the downstream side of the flow rate regulating portion, so that the cooling liquid in the central portion flows into the communication passage, and the communication passage of the central cooling passage It is characterized in that a small flow rate portion is formed on the further downstream side.

According to this structure, the cooling liquid is surely flowed to the central portion where thermal stress is likely to occur, and the flow resistance is high,
Bypassing the end portion, which does not necessarily require a large amount of cooling liquid, can be easily realized. Therefore, it is possible to provide a cylinder head cooling structure for an internal combustion engine that can efficiently cool the central portion of the cylinder head and further increase cooling efficiency by appropriately distributing the flow rate of the cooling liquid as a whole of the cylinder head. .

According to a fourth aspect of the present invention, there is provided a cylinder head cooling structure for an internal combustion engine according to any one of the first to third aspects, wherein the central portion is occupied by the large flow rate portion and the end portion is occupied by the small flow rate portion. It is characterized by

According to this structure, the central portion where thermal stress is likely to occur can be efficiently cooled, and further, the cooling liquid flow rate can be appropriately distributed in the entire cylinder head to enhance the cooling efficiency. Can be provided.

A cylinder head cooling structure for an internal combustion engine according to a fifth aspect is the cylinder head cooling structure for an internal combustion engine according to any one of the second to fourth aspects, wherein there are a plurality of the inflow portions, and at least one of the inflow portions is on the upstream side of the flow rate regulating portion. And an intermediate inflow portion that forms a flow path through which the cooling liquid flows to the central portion through the communication passage.

According to this structure, by providing the intermediate inflow portion on the upstream side of the flow rate regulating portion, it is possible to more effectively assist the flow of the cooling liquid through the communication passage to the central portion. Therefore, the central portion of the cylinder head can be cooled more efficiently than in the second to fourth aspects.

A cylinder head cooling structure for an internal combustion engine according to a sixth aspect is the cylinder head cooling structure according to any one of the first to fifth aspects, wherein the cylinder head includes two intake ports and two exhaust ports in each combustion chamber. It is characterized in that it is used for an internal combustion engine in which cylinders or more are arranged.

According to this structure, even in the case of a cylinder head having a large number of intake ports and exhaust ports such as an internal combustion engine having four valves and three or more cylinders, the central portion of the cylinder head can be efficiently used. Can be cooled,
It is possible to provide a cylinder head cooling structure for an internal combustion engine that can improve cooling efficiency by appropriately distributing the flow rate of the cooling liquid as the entire cylinder head.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, the first embodiment will be described.

(Embodiment 1) FIG. 1 is a horizontal sectional view of a cylinder head 1 of an internal combustion engine according to Embodiment 1, as viewed from the side opposite to a cylinder block (not shown), that is, from the upper side. The cylinder head 1 is shown for a four-valve in-line four-cylinder internal combustion engine. The cylinder head 1 is integrally formed as an aluminum alloy casting.

The cylinder head 1 is provided for each cylinder.
Two intake ports 11a and 11b, 12a and 12b, 13a and 13 are provided with an intake valve and an exhaust valve (not shown).
b, 14a and 14b, and two exhaust ports 21a and 2
1b, 22a and 22b, 23a and 23b, 24a and 24
and b. Then, all the intake ports and the exhaust ports are arranged in a line to form an intake port row 10 and an exhaust port row 20. The intake port row 10 and the exhaust port row 20 are closely opposed to each other. In the following description, for the intake port row 10, all the intake ports are also collectively referred to as the intake port 10, and for the exhaust port row 20, all the exhaust ports are also collectively referred to as the exhaust port 20.

Regarding the intake port 10, two intake port wall portions 11c, 1c are integrally formed for each cylinder.
2c, 13c, 14c, and the exhaust port 20 is formed of all the exhaust ports 21a to 24b.
Is formed by an exhaust port wall portion 20c that is integrally formed. The intake port 10 and the exhaust port 20 formed in this way are open on the lower surface side where the combustion chamber (not shown) is located. Each of these ports is formed by casting using a core when the cylinder head 1 is molded by casting or the like.

The intake port wall portions 11c, 12c,
The fuel injection valve insertion port 11 is provided in each of 13c and 14c on the side facing the exhaust port row 20 between the two intake ports.
d, 12d, 13d and 14d are formed. These fuel injection valve insertion ports 11d to 14d are provided by machining so as to open at the center of a cylinder (not shown) of each cylinder.

The intake port 10 and the exhaust port 20
Cooling the cylinder head 1 heated from the combustion chamber (not shown) between the cylinder head peripheral wall portion 4 which surrounds the cylinder head 1 and constitutes the outer shape of the cylinder head 1 and the periphery of the intake port wall portions 11c to 14c and the exhaust port wall portion 20c. A cooling water passage 5 is formed as a cooling liquid passage for performing the above. It should be noted that the cooling water path 5 is formed by punching out using a core when the cylinder head 1 is formed by casting or the like, and at this time, a part of the intake port wall portion or the exhaust port wall portion is formed. It is formed so as to be connected to the cylinder head peripheral wall portion 4. In the cylinder head 1 shown in FIG. 1, an example in which the exhaust port wall portion 20c is connected is illustrated.

The cooling water path 5 includes the intake port wall portions 11c to 11c.
Intake side cooling passage 6 formed between 14c and cylinder head peripheral wall portion 4, exhaust side cooling passage 8 formed between exhaust port wall portion 20c and cylinder head peripheral wall portion 4, and intake port wall portion A central cooling passage 7 formed between 11c to 14c and the exhaust port wall portion 20c is provided.

The cylinder head 1 is cooled by flowing cooling water as a cooling liquid from the inflow portion to the outflow portion in the cooling water passage 5 constructed as described above. A plurality of inflow portions are provided, and the intake-side inflow portions 30a and 30b provided near the intake port 11a, which is the most upstream side of the intake-side cooling passage 6 or the central cooling passage 7, as well as the uppermost stream of the exhaust-side cooling passage 8. The exhaust side inflow portion 31 provided near the exhaust port 21a on the side, and the intake side cooling passage 6 as described later.
Intermediate outflow part 3 which allows cooling water to flow in from the middle of
2a, 32b, 32c and 32d are provided. These inflow portions are formed as holes communicating with a cooling passage formed in a cylinder block (not shown). Further, the outflow portion 33 is formed at a position on the most downstream side of the intake side cooling passage 6 so as to form a communication port with the outside in a part of the cylinder head peripheral wall portion 4. As the cooling liquid, a cooling liquid other than cooling water, such as cooling oil, may be used.

Between the central cooling passage 7 and the intake cooling passage 6, a plurality of intake port wall portions are formed so as to be sandwiched between the central cooling passage 7 and the intake cooling passage 6. A communication path is formed. That is, the intake port wall portion 11c
And 12c, a communication passage 34a is formed between the wall portions 12c and 13c, and a communication passage 34c is formed between the wall portions 13c and 14c.

In addition, a plurality of flow rate regulating portions are provided in the middle of the intake side cooling passage 6 which communicates with the central cooling passage 7.
This flow rate restricting part is for suppressing the inflow of cooling water into the intake side cooling passage 6, and is formed so as to project from the cylinder head peripheral wall part 4 toward the intake port wall part. That is, in the cylinder head 1 shown in FIG. 1, the flow rate restricting portion 35a is formed so as to partially protrude from the cylinder head peripheral wall portion 4 toward the two integrally formed intake ports in the intake port wall portions 12c and 13c.
And 35b are formed.

The above-mentioned intermediate inflow portions 32b to 32d are provided near the flow rate restricting portions 35a and 35b, and the intermediate inflow portion 3 is also provided near the intake port 11b.
2a is provided. That is, the intermediate inflow portion 32a
Is provided at a position where the cooling water is spouted from the upstream side of the communication passage 34a, and the intermediate inflow part 32b is located in the vicinity of the intake port 12a slightly upstream of the flow rate restricting part 35a.
The intermediate inflow portion 32c is provided on the downstream side of the flow rate regulating portion 35a, on the upstream side of the communication passage 34b, and the intermediate inflow portion 32d is provided on the upstream side of the flow rate regulating portion 35b, in the vicinity of the intake port 13a. All of these allow cooling water to flow out from the middle of the intake side cooling passage 6.

The above is the cooling structure of the cylinder head 1. Next, the cooling action will be described together with the flow state of the cooling water in the cylinder head 1.

First, the cooling water flows into the cylinder head 1 from the respective inflow portions. Although the inflow portions are provided at a plurality of locations as described above, the intake-side inflow portions 30a, 30b, which are provided on the upstream side of the intermediate inflow portions 32a to 32d,
And it mainly flows in from the exhaust side inflow part 31. However, the cooling water also flows in from the intermediate inflow portions 32a to 32d.

The cooling water flowing from the intake side inflow portion 30a mainly flows along the intake side cooling passage 6. This flow direction is indicated by arrow A2. Further, the cooling water that has flowed in from the intake-side inflow portion 30b partially flows toward the central cooling passage 7 along the arrow A1. However, since the central cooling passage 7 has a narrow passage space and a large flow resistance, it is less likely to flow into the central cooling passage 7 than the intake side cooling passage 6. Part of the cooling water that has flowed in from the intake side inflow portion 30b merges with the cooling water that has flowed in from the intake side inflow portion 30a and also flows into the intake side cooling passage 6. By the way, not only the intake side inflow portion 30a but also the intake side inflow portion 30a is provided, so that the inflow to the central cooling passage 7 is promoted. Note that, in FIG. 1, in order to facilitate understanding of the structure and the like of each cooling passage, it is shown slightly different from the actual dimension / shape ratio.

The cooling water flowing from the intake side inflow portion 30a flows along the arrow A2, joins the cooling water flowing from the intermediate inflow portion 32a, and flows further downstream. At this time, a flow rate restricting portion 35a is provided on the downstream side of the intake side cooling passage 6, and the flow resistance portion 6b which is a flow path formed between the flow rate restricting portion 35a and the intake port wall portion 12c. Since the pressure loss is large, the inflow of cooling water from the upstream side is suppressed in the flow path 6a which is the intake side cooling path 6 adjacent to the intake port 12a.

Since the cooling water also flows in from the intermediate inflow portion 32b located on the upstream side of the flow rate regulating portion 35a, the inflow of cooling water from the upstream side into the flow path 6a is further suppressed. A part of the cooling water that has flowed in from the intermediate inflow portion 32b flows in the direction in which the flow resistance on the side opposite to the flow resistance portion 6b on the downstream side is small, that is, in the direction of arrow A6.

In this way, the cooling water that has been suppressed from flowing into the flow path 6a and has flowed from the upstream side and the cooling water that has flowed from the intermediate inflow portion 32a join together and flow into the communication passage 34a. The cooling water flowing into the communication passage 34a passes through the communication passage 34a and then flows into the central cooling passage 7 as indicated by an arrow A5. At this time, it joins the cooling water flowing along the arrow A3 from the upstream side of the central cooling passage 7. Therefore, the cooling water that flows in and merges along A3 and A5 flows into the flow passage 7a that is the central cooling passage 7 formed by the intake port wall portion 12c and the exhaust port wall portion 20c.

The flow passage 7a is a portion (hereinafter, referred to as "central portion 37") located at the center of the port row in the central cooling passage 7 together with the flow passage 7b which will be described later, and excessive thermal stress is likely to occur. It is a part. Therefore, as described above, the structure that promotes the flow of the cooling water to the flow path 7a can be realized, so that a large flow rate portion in which the flow of the cooling water is large is formed in the flow path 7a, that is, the central portion 37, and the central portion 37 is It is possible to cool efficiently and suppress the generation of excessive thermal stress. As will be described later, this large flow rate part
It is formed in the central portion 37 formed by the flow paths 7a and 7b.

The cooling water flowing into the flow path 7a from the directions of arrows A3 and A5 passes through the flow path 7a and flows in the direction of arrow A7. Then, it joins with the cooling water flowing in from the communication passage 34b. The cooling water flowing into the communication passage 34b flows into the intake side cooling passage 6 from the intermediate inflow portions 32c and 32d. That is, the cooling water flowing from the intermediate inflow portion 32c partially flows in the direction of the arrow A8 because the flow rate restricting portion 35b is provided on the downstream side, and the cooling water flowing from the intermediate inflow portion 32d is downstream. Flow control unit 3 on the side
Since part 5b is provided, a part of the arrow A1 on the upstream side is provided.
It will flow in the 0 direction. In this way, the cooling water from the directions of the arrows A8 and A10 merges and flows into the communication passage 34b, and after passing through the communication passage 34b, flows into the direction of arrow A9 and merges with the cooling water from the direction of arrow A7.

Thus, the cooling water from the directions of the arrows A7 and A9 is supplied to the intake port wall portion 13c and the exhaust port wall portion 20c.
The flow path 7b formed by being sandwiched between and, that is, the central portion 3
It flows into the latter half of 7. This allows the central portion 37
In the latter half of the flow path, the large flow rate part where the flow of cooling water is large is the flow path 7a
And the flow passage 7b is efficiently cooled like the flow passage 7a, the central portion 37 can be prevented from excessively high temperature, and the occurrence of excessive thermal stress can be suppressed. .

A part of the cooling water that has passed through the flow path 7b flows downstream along the narrow central cooling path 7 (arrow A1).
3 directions), the remaining portion flows into the communication passage 34c (direction of arrow A11), passes through the communication passage 34c and flows into the intake side cooling passage 6 (direction of arrow A12). This allows
A small flow rate part where the flow of the cooling water is small is formed in the flow path 7c which is sandwiched between the intake port wall part 14c and the exhaust port wall part 20c on the downstream side of the communication passage 34c. The cooling water flowing downstream through the central cooling passage 7 via the flow passage 7c flows out in the arrow A14 direction, and the cooling water flowing downstream in the intake side cooling passage 6 flows out in the arrow A15 direction. As described above, the cooling water flowing from the exhaust-side cooling passage 8 joins with the cooling water, and the outflow portion 3
3 flows out of the cylinder head 1.

Regarding the cooling water flowing through the exhaust side cooling passage 8, first, the cooling water flowing from the inflow portion 31 located on the most upstream side of the exhaust side cooling passage 8 flows in the direction of the arrow B1 and remains as it is on the exhaust side. It flows through the cooling passage 8, that is, between the exhaust port wall portion 20c and the cylinder head peripheral wall portion 4 to the downstream. Then, it flows out from the exhaust side cooling passage 8 in the direction of the arrow B2, merges with the cooling water from the arrows A14 and A15, and flows out from the outflow portion 33 to the outside. The cooling water flowing out to the outside is circulated through a radiator (not shown) or the like and used again for cooling the cylinder head 1.

As described above, according to the cylinder head cooling structure for the internal combustion engine of the first embodiment, the communication passage 34a for guiding the cooling water to the central portion 37 is formed,
Further, the intake side cooling passage 6 is provided by the flow rate control unit 35a and the like.
Since the inflow of cooling water into the central portion 37 is suppressed through the communication passage 34a and the like, the inflow of cooling water into the central portion 37 is promoted. As a result, the intake port 10 and the exhaust port 20
A large flow rate portion is formed in the central portion 37 where the flow resistance is high between the two and the large thermal stress is likely to occur, and the central portion 37 can be efficiently cooled.

Further, according to the cylinder head 1, a communicating passage is provided to the flow passage 7c which is one of the downstream sides of the end portion other than the central portion 37 of the central cooling passage 7 which does not necessarily need to flow a large amount of cooling water. Intake side cooling passage 6 through 34c
Can be diverted to. As a result, in the central cooling passage 7 having a high flow resistance, the central portion 37 where large thermal stress is likely to occur can be intensively cooled. That is, the central portion 37 is efficiently cooled, and the flow resistance is high, but the end portion of the central cooling passage 7 that does not necessarily require a large amount of cooling water is diverted, and a small flow rate portion is formed in this portion. As a whole of the path 5, the pressure loss can be reduced and the flow rate can be increased. Therefore, it is possible to provide a cylinder head cooling structure for an internal combustion engine that can improve cooling efficiency by appropriately distributing the flow rate of cooling water as the entire cylinder head. In the cylinder head 1, the central portion 3 of the end portions is
Not only the flow passage 7c on the downstream side of 7 but also the upstream side of the central cold portion 37 which is the other end portion, that is, the central cooling passage 7 sandwiched between the intake port wall portion 11c and the exhaust port wall portion 20c. A small flow rate portion is also formed in the flow passage 7d.

The cylinder head 1 has a structure in which the intake side cooling passage 6 communicates with the central cooling passage 7 through the communication passage 34a or the like, but this is not always the case, and, for example, in FIG. In the cylinder head 1,
It may be configured such that the left and right are inverted. That is, the intake port wall portion is configured as an intake port wall portion integrally forming all the intake ports, and one end of the upstream side thereof is connected to the cylinder head peripheral wall portion, and the exhaust side cooling passage 8 is the central cooling passage. It may be a structure or the like communicated with 7. Further, both the intake side cooling passage 6 and the exhaust side cooling passage 8 may be structured to communicate with the central cooling passage 7.

Example 2 Next, Example 2 of the present embodiment.
A cylinder head cooling structure for an internal combustion engine according to the present invention will be described. FIG. 2 is a schematic horizontal sectional view of a cylinder head 2 of an internal combustion engine according to a second embodiment, as viewed from the side opposite to a cylinder block (not shown), that is, from the upper side. The cylinder head 2 is an example in which the present invention is applied to the case of a two-valve in-line three-cylinder internal combustion engine. In the description of the embodiments, elements having the same structure and function as those of the cylinder head 1 will be denoted by the same reference numerals, and overlapping description will be appropriately omitted. .

The cylinder head 2 includes a cylinder head peripheral wall portion 4, an intake port row 10 including intake ports 11, 12, and 13, an exhaust port row 20 including exhaust ports 21, 22, and 23, and an upstream side. Inflow part 30 provided
a, 30b, 31 and an outflow portion 33 provided on the downstream side. The intake ports 11, 12, 13 are formed by the intake port wall portions 11c, 12c, 13c, respectively, and the exhaust ports 21-23 are formed by the exhaust port wall portion 20c.
The exhaust port wall portion 20c has one upstream end connected to the cylinder head peripheral wall portion 4. An exhaust side cooling passage 8 is provided between the cylinder head peripheral wall portion 4 and the exhaust port wall portion 20c, and an intake side cooling passage 6 is provided between the cylinder head peripheral wall portion 4 and the intake side port wall portions 11c to 13c.
The exhaust port wall portion 20c and the intake port wall portion 1 are formed.
A central cooling passage 7 is formed between 1c and 13c. A communication passage that connects the central cooling passage 7 and the intake-side cooling passage 6 is provided between the intake port wall portions. That is, the communication passage 34 is provided between the intake port wall portions 11c and 12c.
a is a communication passage 3 between the intake port wall portions 12c and 13c.
4b is provided. Further, in the middle of the intake side cooling passage 6, a flow rate restricting portion 35 is provided at a position corresponding to the intake port wall portion 12c so as to project from the cylinder head peripheral wall portion 4 and narrow the intake side cooling passage 6.

The main flow directions of the cooling water in the cylinder head 2 are shown by arrows A1 to A8, B1 and B2. The cooling water that has flowed in from the inflow portions 30a and 30b flows in the directions of arrows A2 and A1, respectively. However, a large amount of cooling water flows in the direction of arrow A2 where the flow path is wide and the flow resistance is small. The cooling water flowing in the direction of arrow A2 is prevented from flowing into the downstream side of the intake side cooling passage 6 by the flow rate restricting portion 35 located on the downstream side thereof, and a part of the cooling water flows into the communication passage 34a. After flowing through the communication passage 34a in the direction of arrow A3,
It merges with the cooling water from the direction of arrow A1 and flows in the direction of arrow A4. A portion where the flow in the direction of the arrow A4 is formed, that is, a portion of the central cooling passage 7 sandwiched between the intake port wall portion 12c and the exhaust port wall portion 20c (hereinafter, "central portion 37").
Is a portion in the cylinder head 2 where a large thermal stress is likely to occur. By thus promoting the flow in the direction of arrow A4, a large flow rate portion in which a large amount of cooling water flows is present in the central portion 37. Formed, this central portion 37
Will be cooled efficiently.

Part of the cooling water that has passed through the central portion 37 flows downstream of the central cooling passage 7 (flows in the direction of arrow A8 through the direction of arrow A6), and the rest flows in the communication passage 34b ( Flow in the intake side cooling passage 6 downstream (direction of arrow A7). As a result, a small flow rate portion is formed in a portion of the end portion of the central cooling passage 7 other than the central portion 37 located on the downstream side. Then, the cooling water from the arrow A8 direction and the cooling water from the arrow A7 direction merge and flow out from the outflow portion 33 to the outside.

The cooling water flowing from the inflow part 31 is
It flows in the direction of arrow B1 and flows downstream in the exhaust side cooling passage 8 (direction of arrow B2), merges with the cooling water from the directions of arrows A6 and A7, and flows out from the outflow portion 33 to the outside.

As described above, also in the cylinder head 2 of the internal combustion engine having two valve type three cylinders, the central portion of the cylinder head can be efficiently cooled, and the flow rate of the cooling water is appropriately distributed as the whole cylinder head. As a result, it is possible to provide a cylinder head cooling structure for an internal combustion engine that can improve cooling efficiency.

(Example 3) Finally, a cylinder head cooling structure for an internal combustion engine according to Example 3 of the present embodiment will be described. FIG. 3 schematically shows a horizontal cross-sectional view of the cylinder head 3 of the internal combustion engine according to the third embodiment, as viewed from the side opposite to the cylinder block (not shown), that is, from the upper side. The cylinder head 3 is an example in which the present invention is applied to a four-valve, two-cylinder internal combustion engine. In the description of the embodiments, elements having the same structure and function as those of the cylinder head 1 or 2 will be described with the same reference numerals, and overlapping description will be omitted as appropriate. And

The cylinder head 3 includes a cylinder head peripheral wall portion 4, an intake port row 10 composed of intake ports 11, 12, 13, 14 and exhaust ports 21, 22, 23 ,.
The exhaust port row 20 is composed of 24, inflow portions 30a, 30b, 31 provided on the upstream side of the cooling water path 5, and an outflow portion 33 provided on the downstream side. Intake port 1
1 to 14 are intake port wall portions 11c, 12c, 13c,
14c, respectively, and exhaust ports 21-2
3 is integrally formed by the exhaust port wall portion 20c,
One end on the upstream side of the exhaust port wall portion 20c is connected to the cylinder head peripheral wall portion 4. The intake ports 11, 1
2, exhaust ports 21 and 22 are in one cylinder, intake port 1
3, 14 and the exhaust ports 23, 24 correspond to one cylinder.

An exhaust side cooling passage 8 is provided between the cylinder head peripheral wall portion 4 and the exhaust port wall portion 20c, and an intake side cooling passage 6 is provided between the cylinder head peripheral wall portion 4 and the intake side port wall portions 11c to 14c. And the central cooling passage 7 is formed between the exhaust port wall portion 20c and the intake port wall portions 11c to 14c. A communication passage that connects the central cooling passage 7 and the intake-side cooling passage 6 is provided between the intake port wall portions. That is, the communication passage 34a is provided between the intake port wall portions 11c and 12c, the communication passage 34b is provided between the intake port wall portions 12c and 13c, and the communication passage 34c is provided between the intake port wall portions 13c and 14c. Has been. Further, in the middle of the intake side cooling passage 6, at the positions corresponding to the intake port wall portions 12c and 13c, the flow rate restricting portion 3 is projected from the cylinder head peripheral wall portion 4 so as to narrow the intake side cooling passage 6.
5a and 35b are provided.

The main flowing directions of the cooling water in the cylinder head 3 are shown by arrows A1 to A9, B1 and B2. The cooling water that has flowed in from the inflow portions 30a and 30b flows in the directions of arrows A2 and A1, respectively. However, a large amount of cooling water flows in the direction of arrow A2 where the flow path is wide and the flow resistance is small. The cooling water flowing in the direction of the arrow A2 is prevented from flowing into the downstream side of the intake side cooling passage 6 by the flow rate restricting portion 35a located on the downstream side thereof, and a part of the cooling water flows into the communication passage 34a. And, a part of the communication passage 34 is in the direction of arrow A3.
After flowing through a, it merges with the cooling water from the direction of arrow A1 and flows in the direction of arrow A4. The remaining cooling water flows through the flow control unit 35.
It passes between a and the intake port wall portion 12c and flows along the intake side cooling passage 6.

Further, since the flow rate regulating section 35b is also provided on the downstream side of the flow rate regulating section 35a, the inflow of cooling water into the intake side cooling passage 6 during this time is suppressed. Therefore, most of the cooling water from the arrow A4 direction flows in the arrow A5 direction. These portions where the flow in the arrow A4 direction is formed and the portions where the flow in the arrow A5 direction is formed, that is, the central cooling passage 7 sandwiched between the intake port wall portions 12c and 13c and the exhaust port wall portion 20c. Part (below,
The "central portion 37" is a portion of the cylinder head 3 where large thermal stress is likely to occur, but the flow of cooling water is promoted in this way, so that a large amount of cooling water flows in the central portion 37. A large flow rate portion is formed, and this central portion 37 is efficiently cooled. That is, the upstream side flow control unit 35a and the downstream side flow control unit 3
5b makes it possible to guide the cooling water to the central portion 37 so that the cooling water flows sufficiently.

A part of the cooling water that has passed through the central portion 37 flows downstream of the central cooling passage 7 (flows in the direction of arrow A8 through the direction of arrow A7), and the rest flows in the communication passage 34c ( (Direction of arrow A6), and flows downstream through the intake side cooling passage 6 (direction of arrow A9). As a result, a small flow rate portion is formed in a portion of the end portion of the central cooling passage 7 other than the central portion 37 located on the downstream side. Then, the cooling water from the arrow A8 direction and the cooling water from the arrow A9 direction merge and flow out from the outflow portion 33 to the outside.

The cooling water flowing from the inflow part 31 is
It flows out in the direction of arrow B1 and flows downstream in the exhaust side cooling passage 8 (direction of arrow B2), merges with the cooling water from the directions of arrows A7 and A9, and flows out from the outflow portion 33 to the outside.

As described above, also in the cylinder head 3 of the internal combustion engine having the four-valve type two-cylinder, the central portion of the cylinder head can be efficiently cooled, and the cooling water flow rate is appropriately distributed as the whole cylinder head. As a result, it is possible to provide a cylinder head cooling structure for an internal combustion engine that can improve cooling efficiency.

The above is a description of the present embodiment. Note that the embodiment is not limited to the above, and may be modified as follows, for example. (1) In the present embodiment, the case where the present invention is applied to a four-valve type four-cylinder, two-valve type three-cylinder, four-valve type two-cylinder internal combustion engine is exemplified, but The internal combustion engine is not limited to the embodiment, and includes a port row in which a plurality of intake valves and exhaust valves are arranged,
The present invention can be applied.

(2) In the present embodiment, all the flow rate control portions have a structure in which they partially project from the cylinder head peripheral wall portion, but this does not necessarily have to be the case. It may be formed continuously along the portion or the port wall portion so as to have a length corresponding to the central portion of the central cooling passage.

(3) It is not always necessary to provide a plurality of communication passages. For example, when the length of the port row in the valve arrangement direction is short, a communication passage for guiding the inflow to the central cooling passage is provided. Alternatively, only one location may be provided on the upstream side.

[0062]

According to the first aspect of the present invention, the communication passage for guiding the cooling liquid to the central portion is formed, and the flow rate of the cooling liquid in the central portion is changed to the end portion via the communication passage. Therefore, the flow resistance between the intake port and the exhaust port is high, and the central portion of the cylinder head where thermal stress is likely to occur can be efficiently cooled. Further, according to this configuration, the end portion that does not necessarily need to flow a large amount of cooling liquid can be diverted to the intake side cooling passage or the exhaust side cooling passage through the communication passage. As a result, in the central cooling passage having a high flow resistance, it is possible to intensively cool the central portion where thermal stress is likely to occur. That is, the central portion is efficiently cooled, and the flow resistance is high, but the end portion that does not necessarily require a large amount of cooling liquid is diverted, and the pressure loss is reduced and the flow amount is increased as a whole cooling liquid path. be able to. Therefore, it is possible to provide a cylinder head cooling structure for an internal combustion engine that can improve cooling efficiency by appropriately distributing the flow rate of the cooling liquid as the entire cylinder head.

According to the invention of claim 2, the flow rate regulating portion is provided in the middle of the intake side cooling passage or the exhaust side cooling passage communicating with the central cooling passage, and the invention according to claim 1 is provided. The same effect as can be obtained.

According to the third aspect of the present invention, it is possible to reliably flow the cooling liquid to the central portion where thermal stress is likely to occur and to bypass the end portion that has a high flow resistance but does not necessarily require a large amount of cooling liquid. It can be realized easily. Therefore, it is possible to provide a cylinder head cooling structure for an internal combustion engine that can efficiently cool the central portion of the cylinder head and further increase cooling efficiency by appropriately distributing the flow rate of the cooling liquid as a whole of the cylinder head. .

According to the fourth aspect of the invention, the cylinder of the internal combustion engine can efficiently cool the central portion where thermal stress is likely to occur, and further appropriately distribute the cooling liquid flow rate as the entire cylinder head to enhance the cooling efficiency. A head cooling structure can be provided.

According to the fifth aspect of the present invention, by providing the intermediate inflow portion on the upstream side of the flow rate regulating portion, it is possible to more effectively assist the flow of the cooling liquid to the central portion through the communication passage. it can. Therefore, the central portion of the cylinder head can be cooled more efficiently than in the second to fourth aspects.

According to the sixth aspect of the invention, even in the case of a cylinder head having a large number of intake ports and exhaust ports such as an internal combustion engine having four valves and three or more cylinders, the central portion of the cylinder head is used. Can be cooled efficiently,
Further, it is possible to provide a cylinder head cooling structure for an internal combustion engine, which can enhance cooling efficiency by appropriately distributing the flow rate of the cooling liquid as a whole cylinder head.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view of a cylinder head of an internal combustion engine according to a first embodiment of the present embodiment.

FIG. 2 is a horizontal sectional view of a cylinder head of an internal combustion engine according to a second example of the present embodiment.

FIG. 3 is a horizontal sectional view of a cylinder head of an internal combustion engine according to Example 3 of the present embodiment.

[Explanation of symbols]

1-3 cylinder head 4 Cylinder head peripheral wall 5 Cooling water route 6 Intake side cooling passage 7 Central cooling channel 8 Exhaust side cooling passage 10 Intake port row 11-14 Intake port 11c-14c Intake port wall 20 exhaust port row 20c Exhaust port wall 21-24 Exhaust port 30a, 30b intake side inflow section 31 Exhaust side inlet 33 Outflow section 34a-34c communication passage 35a, 35b Flow rate control unit A1-15, B1, B2 Flow direction arrow 37 Central part

Claims (6)

[Claims] 1. By flowing a cooling liquid from an inflow portion to an outflow portion in a cooling liquid passage formed in a cylinder head of an internal combustion engine having a port row in which a plurality of intake valves and exhaust valves are respectively arranged. A cylinder head cooling structure for cooling the cylinder head heated from a combustion chamber, wherein the cooling liquid passage is formed between an intake port wall portion forming an intake port row and a cylinder head peripheral wall portion. A cooling passage, an exhaust side cooling passage formed between the exhaust port wall portion forming the exhaust port row and the cylinder head peripheral wall portion, and formed between the intake port wall portion and the exhaust port wall portion. A central cooling passage is provided, and a communication passage that communicates the central cooling passage and at least one of the intake-side cooling passage or the exhaust-side cooling passage is formed, and the central passage is formed through the communication passage. cold A large flow rate portion and a small flow rate portion are formed in the passage, and a ratio of the large flow rate portion in the central portion of the central cooling passage is at an end portion other than the central portion of the central cooling passage. A structure for cooling a cylinder head of an internal combustion engine, wherein the structure is formed so as to have a higher ratio than the ratio occupied by the large flow rate portion. 2. At least one communication passage of the communication passages, wherein a flow rate restriction is provided downstream of the communication passage in the intake side cooling passage or the exhaust side cooling passage communicated with the central cooling passage by the communication passage. By providing the portion, the cooling liquid is caused to flow into the central portion via the communication passage, and the large flow rate portion is formed on the downstream side of the communication passage in the central portion. A cylinder head cooling structure for an internal combustion engine as described. 3. A large flow rate portion is formed in the central portion by providing a flow rate regulating portion in at least one of the intake side cooling passage or the exhaust side cooling passage, and at the downstream side of the flow rate regulating portion, 2. The cooling fluid in the central portion is caused to flow into the communication passage by providing the communication passage, and a small flow rate portion is formed on the downstream side of the communication passage in the central cooling passage. Item 3. A cylinder head cooling structure for an internal combustion engine according to Item 2. 4. The cylinder head cooling structure for an internal combustion engine according to claim 1, wherein the large flow rate portion occupies the central portion and the small flow rate portion occupies the end portion. . 5. A plurality of the inflow sections, at least one of the inflow sections being provided on the upstream side of the flow rate regulating section,
The cooling structure for a cylinder head of an internal combustion engine according to any one of claims 2 to 4, which is an intermediate inflow portion that forms a flow path through which the cooling liquid flows through the communication passage to the central portion. 6. The cylinder head is provided with two intake ports and two exhaust ports in each combustion chamber and is used for an internal combustion engine in which three or more cylinders are arranged. 6. A cylinder head cooling structure for an internal combustion engine according to any one of items 5 to 5.