JPH11141396A - Structure of cylinder head of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate formation of a water jacket at the periphery of the root of a plug tower, to prevent the increase of the thickness of the root part of the plug tower, to improve cooling ability of a cylinder head, and to sufficiently improve knocking resistance and durability. SOLUTION: Approximately the whole of a plug tower 12 consists of a cylindrical member 12A different from a cylinder head 13, and the cylindrical member 12A is integrally cast during casting of the cylinder head 13. For example, the root part 12B of the plug tower 12 is molded integrally with the cylinder head 13 made of casting, and the lower end part of the cylindrical member 12A is cast in the root part 12B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a cylinder head of an internal combustion engine, and more particularly to a technique for forming a plug tower in a cylinder head.

[0002]

2. Description of the Related Art In an internal combustion engine, cooling corresponding to the heat load is performed to optimize cooling of a cylinder head, to reduce cooling loss, to prevent knocking, to prevent heat cracks, and the like. It is necessary to improve the durability. By the way, for example, as shown in FIG.
In a four-valve internal combustion engine having two exhaust ports 3 and a plug tower 4 for mounting a spark plug at the center of these ports 2 and 3, a water jacket 5 around the base 4A of the plug tower 4 is provided. This has an important effect on the cooling performance of the cylinder head 1, particularly on the cooling performance of the combustion chamber wall.

[0003]

In the case of a cast cylinder head, the plug tower 4 is mounted on the cylinder head 1.
And are integrally formed by casting. However, when the plug tower 4 is integrally formed with the cylinder head 1 by casting, there are the following problems.

That is, if the lower inner peripheral portion of the core for forming the water jacket 5 has a thin, sharp or complicated shape, this portion is easily damaged and the yield is deteriorated. The lower part of the inner circumference needs to be thick and rounded or have a simple shape with as few steps as possible. When such a core is used, the fillet portion 6 where the plug tower 4 and the wall of the water jacket 5 continue becomes thick, and the base 4A of the plug tower 4 becomes thick.

The thick base 4A of the plug tower 4 becomes a thermally severe part, and the cylinder head 1
In particular, the cooling performance of the combustion chamber, particularly the cooling performance of the combustion chamber wall, is hindered, and the occurrence of knocking phenomena, heat cracks and the like cannot be suppressed. Conventionally, the following technology has been proposed as a technology for improving the cooling performance of an internal combustion engine.

For example, Japanese Unexamined Utility Model Publication No. 60-183249 discloses that a squish portion of a cylinder head forming an upper surface of a squish area of a combustion chamber is provided on an upstream side and a downstream side of a cooling water passage formed in the cylinder head. A technique is disclosed in which a hollow pipe having both ends communicating with each other is cast, and a squish portion is cooled by cooling water flowing in the hollow pipe.

However, if such a technique is applied to a cooling structure around the base of the plug tower,
It is difficult to secure an open end through which the cooling water of the hollow pipe flows, and it is not practically applicable. Also, Japanese Patent Application Laid-Open No.
In Japanese Patent Application Publication No. 18-182, there is disclosed a water flow control unit that extends over a region surrounded by a guide hole wall (plug tower) of a spark plug located at a central portion of each cylinder and surrounding intake valve guide hole walls and exhaust valve guide hole walls. A technology is disclosed in which a cooling water passage section is narrowed between the water flow control section and a combustion chamber wall facing the water flow control section so as to promote cooling of the combustion chamber wall. Have been.

However, in such a technique, although the cooling water flow is changed to enhance the cooling effect of the cylinder head, merely changing the flow of the cooling water merely changes the flow of the cooling water at the base of the plug tower. The local cooling effect of the thick part cannot be expected. In view of the above problems, the present invention facilitates the formation of a water jacket around the base of the plug tower, prevents the base of the plug tower from becoming thicker, and thereby reduces the cooling performance of the cylinder head. It is an object of the present invention to sufficiently improve knocking resistance, durability, etc.

[0009]

Therefore, according to the present invention, a plug tower for mounting a spark plug located at the center of each cylinder extends from the upper deck of the cast cylinder head to the upper surface of the combustion chamber. In a cylinder head of an internal combustion engine provided with a water jacket formed around the plug tower, substantially the entire plug tower is constituted by a cylindrical member separate from the cylinder head, and the cylindrical member is formed by casting the cylinder head. It is characterized in that it is sometimes cast integrally.

The invention according to claim 2 is characterized in that a root portion of a plug tower is integrally formed with the cylinder head, and a lower end portion of the tubular member is cast into the root portion. In the invention according to claim 3, the tubular member forms the entire plug tower, and the lower end surface of the tubular member is cast so as to be flush with the plug seat surface on the inner surface of the upper wall of the combustion chamber. It is characterized by the following.

According to a fourth aspect of the present invention, a portion constituting a combustion chamber upper wall is integrally formed at a lower end portion of the cylindrical member, and the combustion chamber upper wall is formed by casting the cylindrical member. It is characterized by. The invention according to claim 5 is characterized in that a plurality of concave and convex portions for reinforcing the casting joint strength are formed on an outer peripheral surface of a casting portion of the cylindrical member into the cylinder head.

The invention according to claim 6 is characterized in that a flange for reinforcing the casting joint strength is formed on the outer peripheral surface of the casting portion of the cylindrical member to the cylinder head. The invention according to claim 7 is characterized in that a plurality of concave / convex portions for reinforcing and dissipating the casting joint strength are formed on the outer peripheral surface of the tubular member.

The invention according to claim 8 is characterized in that at least the convex portion of the concave and convex portion on the outer peripheral surface of the cylindrical member facing the inside of the water jacket is formed in a fin shape.
The invention according to claim 9 is characterized in that the tubular member is embedded in a core for forming the water jacket at the time of casting the cylinder head, and is integrally cast together with the core at the time of casting the cylinder head. And

The operation of the present invention will be described. If the lower part of the inner periphery of the core for forming the water jacket is made thin, sharp, or complicated in order to make the root of the plug tower thinner, this part is easily damaged. In the invention according to claim 1, since the plug tower is substantially entirely formed of a cylindrical member separate from the cylinder head, and the cylindrical member is integrally cast when the cylinder head is cast, the plug tower and the water jacket are formed. There is no fillet that connects to the wall.

Accordingly, the thickness of the base of the plug tower can be reduced. In the invention according to claim 2, the lower end portion of the tubular member is firmly cast into the root portion of the plug tower of the cylinder head. In the invention according to claim 3,
The entirety of the plug tower is formed of a cylindrical member, so that it is not necessary to form a root portion of the plug tower on the cylinder head side, and a thick portion is reduced.

In the invention according to claim 4, it is not necessary to provide not only the root of the plug tower but also the upper wall of the combustion chamber on the cylinder head side. In the invention according to claims 5 and 6, a plurality of irregularities or flanges on the outer peripheral surface of the cylindrical member bite into the cylinder head, and the casting strength is improved. In the invention according to claim 7, the casting joint strength is improved and the heat dissipation is also improved.

In the invention according to claim 8, the heat dissipation is further improved by the fin-shaped projections. In the invention according to claim 9, the core and the cylindrical member are integrally incorporated into the casting mold, and the core is held by the cylindrical member, so that damage to the core and the like are prevented, The incorporation of the core and the cylindrical member into the casting mold is improved.

[0018]

According to the first aspect of the present invention, the thickness of the root portion of the plug tower can be reduced, and the cooling performance of the cylinder head, particularly the cooling performance of the combustion chamber wall, can be improved. Generation, heat cracks and the like can be effectively suppressed.

According to the second aspect of the present invention, the tubular member can be constituted by a simple pipe or the like, and the casting strength of the tubular member is improved. According to the third aspect of the present invention, it is not necessary to form the root portion of the plug tower on the cylinder head side, and the thick portion is further reduced. As a result, the occurrence of a knocking phenomenon and the occurrence of a heat crack can be more effectively suppressed.

According to the fourth aspect of the invention, it is possible to improve the castability of the cylinder head. Claim 5
According to the inventions of (6) and (7), the casting strength of the tubular member is improved. According to the invention according to claim 7, the improvement of the casting joint strength of the tubular member and the improvement of the heat dissipation are simultaneously improved.

According to the eighth aspect of the invention, higher heat dissipation can be obtained. According to the ninth aspect, breakage of the core can be prevented, yield can be improved, and the manufacturability of cylinder head casting can be improved.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the attached drawings. 1 and 2, a spark plug mounting plug tower 12 located at the center of each cylinder 11 of a four-valve internal combustion engine 10 having two intake ports 16 and two exhaust ports 17 is a cast cylinder. Head 1
A water jacket 15 is formed around the plug tower 12 so as to extend from the upper deck portion 13 </ b> A to the upper surface of the combustion chamber 14.

Here, according to the present invention, substantially the entire plug tower 12 is formed in a cylindrical member 1 separate from the cylinder head 13.
2A, and the cylindrical member 12A is
3 is characterized in that it is cast integrally during casting. That is, the embodiment of FIG.
3, a base portion 12B of the plug tower 12 is integrally formed, and the lower end portion of the tubular member 12A is cast into the base portion 12B.

In this case, the cylindrical member 12A is provided to extend from the upper deck portion 13A of the cylinder head 13 to the combustion chamber 14 side, and a water jacket 15 is formed around the cylindrical member 12A. The embodiment of FIG.
A plurality of uneven portions 12a are formed on the outer peripheral surface of the 2A for reinforcing and dissipating the cast bonding strength.

FIG. 4 shows an embodiment in which the cylindrical member 12A is cast into the cylinder head 13, ie, the upper deck 13A.
The flanges 12b and 12c for reinforcing the casting bonding strength are formed on the outer peripheral surface of the casting portion to the root portion 12B. In the above embodiment, the portion of the plug tower 12 other than the base portion 12B is formed by the cylindrical member 12A, but the entire plug tower may be formed by a cylindrical member.

FIG. 5 shows this embodiment. In this embodiment, the lower end surface of the cylindrical member 12C constituting the entire plug tower 12 is the plug seat surface 1 on the inner surface of the upper wall of the combustion chamber 14.
It is cast so as to be flush with 8. In this case, the lower end side of the cylindrical member 12C is formed to have a smaller diameter than the others, and the outer peripheral surface of the casting portion to the upper wall of the combustion chamber 14 of the casting portion to the cylinder head 13 includes: A plurality of concave-convex portions 12d for reinforcing the cast bond strength are formed.

In the above embodiment, the cylindrical member 1
It is preferable that at least the protrusions of the concave and convex portions on the outer peripheral surface of the portion facing the inside of the water jacket 15 of the 2A and 12C are formed in a fin shape in order to further improve the heat dissipation. FIG.
Shows this embodiment, in which the entire plug tower 12 is formed of a cylindrical member 12C, and the outer surface of a portion of the cylindrical member 12C facing the inside of the water jacket 15 and an outer peripheral surface of a casting portion into the upper deck 13A. Many fins 1
9 are provided.

In the embodiment shown in FIG. 7, a portion 12E constituting the upper wall of the combustion chamber 14 is integrally formed at the lower end of the cylindrical member 12D, and the upper wall of the combustion chamber 14 is formed by casting the cylindrical member 12D. It is made to be done. In this case, the combustion chamber 1
4, an outlet 12 e of the exhaust port 17 and an opening 12 serving as an inlet of the intake port 16
In addition to the formation of f, a plurality of concave and convex portions 12g are formed on the outer peripheral surface of a portion to be cast into the bottom of the cylinder head 13 to reinforce casting joint strength.

In each of the above embodiments, when casting the tubular member, the tubular member is embedded in a core for forming the water jacket 15 at the time of casting the cylinder head 13, and the cylinder head is formed together with the core. It is preferable that the casting is performed integrally during the casting of No. 13. Although not shown, a female screw portion for screwing the spark plug is formed on the inner peripheral surface of the lower end portion of the cylindrical member or the inner peripheral surface of the plug tower root portion on the cylinder head 13 side.

Next, the operation and effect of this embodiment will be described. Substantially the entirety of the plug tower 12 (in the illustrated embodiment, the entirety, and in the illustrated embodiment, the entirety excluding the base)
Is composed of a cylindrical member separate from the cylinder head 13,
Since the cylindrical member is integrally cast when the cylinder head 13 is cast, the plug tower 12 and the water jacket 1 are cast.
There is no fillet that continues to the five walls.

Accordingly, it is possible to make the base of the plug tower 12 thinner. As described above, by reducing the thickness of the base of the plug tower 12, the cooling performance of the cylinder head 13 and particularly the cooling performance of the combustion chamber wall can be improved, and the occurrence of knocking and the occurrence of heat cracks can be suppressed. become able to. Further, each embodiment has the following advantages.

That is, according to the embodiment shown in FIG. 1, the cylindrical member 12A can be constituted by a simple pipe or the like.
Is firmly cast into the base portion 12B of the cylinder head 13 to improve the casting strength of the tubular member 12A. According to the embodiment of FIG.
Since a plurality of concave and convex portions 12a for reinforcing and dissipating the casting joint strength are formed on the outer peripheral surface of the 2A, the casting joint strength can be improved, and the heat dissipation can be improved, and the cooling of the cylinder head 13 can be improved. Properties can be further improved.

Further, according to the embodiment of FIG.
By forming the flanges 12b and 12c for reinforcing the casting joint strength on the outer peripheral surface of the casting portion of the 2A into the cylinder head 13, that is, the upper deck 13A and the casting portion to the root portion 12B. It is possible to further improve the casting bond strength. Further, according to the embodiment of FIG. 5, the lower end surface of the cylindrical member 12C is formed by the cylindrical member 12C so that the plug tower 12 is entirely formed.
Since the casting is performed so as to be flush with the plug seating surface 18 on the inner surface of the upper wall, the thick portion is further reduced, and the cooling performance of the cylinder head 13, particularly the cooling performance of the combustion chamber wall, can be further improved. , The plug tower 12 on the cylinder head 13 side
There is no need to provide a base for the cylinder head 1
3 can improve the castability.

According to the embodiment shown in FIG. 6, when the entire plug tower 12 is formed of a cylindrical member 12C, a large number of fins are formed on the outer peripheral surface of a portion of the cylindrical member 12C facing the water jacket 15. As a result of providing the portion 19, it is possible to further improve the heat dissipation. Further, according to the embodiment of FIG. 7, a portion 12E constituting the upper wall of the combustion chamber 14 is integrally formed at the lower end of the cylindrical member 12D, and the upper wall of the combustion chamber 14 is formed by casting the cylindrical member 12D. As a result, it is not necessary to provide not only the root of the plug tower 12 but also the upper wall of the combustion chamber 14 on the cylinder head 13 side, and the castability of the cylinder head 13 can be further improved.

When the cylindrical member is cast, the cylindrical member is embedded in a core for forming the water jacket 15 and is cast together with the core when the cylinder head 13 is cast. Since the inner peripheral portion of the core is held by the tubular member, breakage of the core can be prevented, and the incorporation of the core and the tubular member into the casting mold can be improved. .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a structure of a cylinder head of an internal combustion engine of the present invention, and is a sectional view taken along the line AA in FIG.

FIG. 2 is a view taken in the direction of arrow B in FIG. 1;

FIG. 3 is a longitudinal sectional view of another embodiment.

FIG. 4 is a longitudinal sectional view of still another embodiment.

FIG. 5 is a longitudinal sectional view of still another embodiment.

FIG. 6 is a longitudinal sectional view of still another embodiment.

FIG. 7 is a longitudinal sectional view of still another embodiment.

FIG. 8 is a longitudinal sectional view showing a conventional plug tower structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Internal combustion engine 11 Cylinder 12 Plug tower 12A Cylindrical member 12B Root part 12C Cylindrical member 12D Cylindrical member 13 Casting cylinder head 13A Upper deck part 14 Combustion chamber 15 Water jacket 16 Intake port 17 Exhaust port

Claims (9)

[Claims] An internal combustion engine having a spark plug mounting plug tower located at the center of each cylinder extending from an upper deck of a cast cylinder head to an upper surface of a combustion chamber, and having a water jacket formed around the plug tower. In an engine cylinder head, an internal combustion engine characterized in that substantially the entire plug tower is formed of a cylindrical member separate from the cylinder head, and the cylindrical member is integrally cast when the cylinder head is cast. Cylinder head structure. 2. The plug head according to claim 1, wherein a base portion of the plug tower is integrally formed with the cylinder head, and a lower end portion of the tubular member is cast into the base portion.
The structure of the cylinder head of the internal combustion engine described in the above. 3. The cylindrical member constitutes an entire plug tower, and the lower end surface of the cylindrical member is cast so as to be flush with the plug seat surface on the inner surface of the upper wall of the combustion chamber. The structure of a cylinder head for an internal combustion engine according to claim 1, wherein 4. A combustion chamber upper wall is formed by integrally molding a portion constituting a combustion chamber upper wall with a lower end portion of the cylindrical member, and casting the cylindrical member. The structure of the cylinder head of the internal combustion engine according to any one of claims 1 to 3. 5. A plurality of projections and depressions for reinforcing casting joint strength are formed on an outer peripheral surface of a casting portion of the cylindrical member to a cylinder head. The structure of the cylinder head of the internal combustion engine according to any one of the above. 6. A method according to claim 1, wherein a flange portion for reinforcing the casting bonding strength is formed on the outer peripheral surface of the casting portion of the cylindrical member to the cylinder head. Or 1
The structure of the cylinder head of the internal combustion engine according to any one of the first to third aspects. 7. The cylindrical member according to claim 1, wherein a plurality of projections and depressions are formed on the outer peripheral surface of the tubular member for reinforcing and dissipating the casting joint strength. 3. The structure of the cylinder head of the internal combustion engine according to 1. 8. The structure of a cylinder head for an internal combustion engine according to claim 7, wherein the projections of the concave and convex portions on the outer peripheral surface of at least a portion of the cylindrical member facing the inside of the water jacket are formed in a fin shape. . 9. The method according to claim 1, wherein the tubular member is embedded in a core for forming the water jacket at the time of casting the cylinder head, and is cast together with the core at the time of casting the cylinder head. Item 9. The structure of a cylinder head of an internal combustion engine according to any one of Items 1 to 8.