JPH0596450U - Cylinder head of internal combustion engine - Google Patents

Abstract

(57) [Summary] [Purpose] To raise the maximum cylinder pressure,
It is necessary to make the span of the reinforcing ribs sufficiently small. A cylinder head which has such a small span structure, is easy to manufacture, and is excellent in strength. [Structure] The bottom wall portion 1 and the reinforcement portion 2 are formed as separate bodies, and the bottom wall portion 1 is formed of a material having higher temperature strength and poorer heat conduction than the reinforcement portion 2, and the joining surfaces of both are formed. The entire surface is made flat, and both are integrally bonded in a solid state in a metallic crystal state by a surface bonding means such as a diffusion bonding method.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a cylinder head for forming a combustion chamber by closing an end of a cylinder in an internal combustion engine.

[0002]

[Prior art and its problems]

 Specific examples of conventional cylinder heads include, for example, the cylinder head described in Japanese Utility Model Laid-Open No. 56-143539 and Motortechnische Zeitschrift Vol. 40 No. 1 (issued in January 1979), page 27. You can As shown in FIGS. 5 to 7, the cylinder head has a bottom wall portion 52 facing the combustion chamber 51, and a reinforcement portion 53 extending from the bottom wall portion 52 in the direction opposite to the combustion chamber 51. A reinforcing rib 54 is formed on the reinforcing portion 53, and a cooling water passage 55 is defined by the reinforcing rib 54. An air passage 56 and an exhaust passage 57, which communicate with the bottom wall portion 52, are formed in the reinforcing portion 53 by the reinforcing ribs 54. The cylinder head has such a complicated structure. Therefore, the entire conventional cylinder head is integrally formed of aluminum casting, cast iron, or the like.

By the way, in recent years, in order to improve the thermal efficiency of the internal combustion engine and improve the engine output, it has become necessary to increase the maximum pressure in the cylinder. Considering this with respect to the cylinder head, it means that in the cylinder head, the thermal response and the mechanical stress in the bottom wall portion 52 increase. Therefore, the thermal stresses σ _th and σ _m will be examined using a simple model shown in FIG.

First, regarding the thermal stress σ _th , σ _th ∝E · α · q · h / λ∝h. In the above equation, E is the longitudinal elastic modulus, α is the coefficient of linear expansion, λ is the thermal conductivity, q is the heat flow density, and h is the wall thickness, but since the above equation does not increase the thermal stress σ _th. Therefore, it is necessary to suppress the increase in the wall thickness h.

On the other hand, the mechanical stress σ _m is σ _m ∝p · (a / h) ² . In the formula, p represents the maximum pressure in the cylinder, and a represents the span of the reinforcing rib 54, but in order to prevent the mechanical stress σ _m from rising from the above formula, the span a of the reinforcing rib 54 should be small. In addition, it is necessary to increase the wall thickness h.

From the above equations, in order to increase the maximum pressure in the cylinder without increasing the thermal stress σ _th and the mechanical stress σ _m , the wall thickness h 1 of the bottom wall portion 52 of the cylinder head is increased. It will be apparent that the span a of the reinforcing rib 54 may be reduced without doing so.

However, in the cylinder head having the above-mentioned integrally cast structure, even if the span a of the reinforcing rib 54 is reduced as described above, there is a limit naturally in working, and therefore the maximum pressure in the cylinder is sufficiently increased. It was impossible to do.

The present invention has been made in view of the above, and an object thereof is to make it possible to sufficiently reduce the span of the reinforcing ribs, thereby making it possible to increase the maximum cylinder pressure. An object is to provide a cylinder head that can be easily manufactured.

[0009]

[Means and actions for solving the problem]

 Therefore, in the cylinder head of the present invention, as shown in FIG. 1 corresponding to the embodiment, the bottom wall portion 1 and the reinforcing portion 2 are separately formed, and the both are made of metal crystal by surface bonding means such as diffusion bonding. They are joined together in a solid state. Examples of the joining method in this case include, but are not limited to, a diffusion joining method, a joining method using a hot isostatic pressing method, and a friction welding method.

By adopting the structure as described above, the span distance of the reinforcing rib 9 provided in the reinforcing portion 2 in advance can be freely set. Therefore, the span of the reinforcing rib 9 can be made sufficiently small, It is possible to increase the maximum pressure in the cylinder and increase the output of the engine without increasing thermal stress and mechanical stress. Further, the reinforcing portion 2 is to be open at one end side before joining, and therefore, when the reinforcing portion 2 is manufactured by, for example, a casting method, its manufacturing is easy. Becomes

Further, the bottom wall portion 1 is made of a heat-resistant metal having a higher temperature strength and a lower heat conduction than the reinforcement portion 2, for example, a nickel alloy (Nimonic 80A), austenitic stainless steel, martensitic stainless steel, etc. As a result, the bottom wall portion 1 facing the combustion chamber is significantly improved in mechanical and thermal strength and has heat insulation properties, so that the cylinder head and hence the engine are improved in durability and thermal efficiency. Is possible. Further, the joint surface between the bottom wall portion 1 and the reinforcing portion 2 is made flat over the entire surface, and both are integrally joined in a solid state in a metallic crystal state by a surface joining means such as diffusion joining. The joint strength is improved, and also in this respect, it is possible to increase the maximum cylinder pressure.

[0012]

【Example】

 Next, specific examples of the cylinder head of the internal combustion engine of the present invention will be described in detail with reference to the drawings.

First, FIG. 1 schematically shows a first embodiment. This cylinder head has a bottom wall portion 1 and a reinforcement portion 2. The bottom surface of the bottom wall portion 1 is arranged in the combustion chamber, and the reinforcement portion 2 is a portion arranged in the opposite direction to the combustion chamber. is there. The bottom wall portion 1 is a plate-shaped member, and has a plurality of through holes, that is, the intake valve holes 3 and 3, the exhaust valve holes 4 and 4, the fuel valve hole 5, the start valve hole 6 and the safety valve. The holes 7 are provided respectively. On the other hand, the reinforcing portion 2 has an outer cylinder 8 having a substantially cylindrical shape and a reinforcing rib 9 that partitions the inside of the outer cylinder 8. The reinforcing rib 9 allows the air supply passage 10, the exhaust passage 11, the fuel passage 12 and the The cooling water passages 13 and the like are sectioned and formed.

As the material used to form the bottom wall portion 1 in the above, since the lower surface of the bottom wall portion 1 is located in the combustion chamber, a high-strength material having low heat conductivity and heat resistance is used. It is preferable to use, for example, a nickel alloy (Nimonic 80A: 20Cr-1Co-2.5Ti-1.3Al), austenitic stainless steel (25Cr-20Ni), martensitic stainless steel (17Cr-7Ni), etc. It is not particularly limited to these, and other steel types can be used. Further, the bottom wall portion 1 can be formed in the above-described shape by subjecting the plate-shaped body to mechanical processing such as machining, but a casting method or a forging method may be adopted.

On the other hand, since the structure of the reinforcing portion 2 is complicated, it is preferable that the reinforcing portion 2 is made of cast iron, cast steel or the like. However, a welded sheet metal structure formed by welding a steel plate or a steel block is used as a machine. It is also possible to form it by processing.

Then, in a state where the holes 3 ... 7 and the passages 10 ... 12 are aligned with each other, the lower end of the reinforcing portion 2, that is, the outer cylinder 8 and The lower end surface of the reinforcing rib 9 is integrally joined by diffusion joining, hot isostatic pressing, friction welding, or the like. Then, if necessary, the joined body is further machined to form a cylinder head.

In the cylinder head as described above, since there is no dimensional limitation as in the cylinder head manufactured by the conventional casting method, the span distance of the reinforcing rib 9 is free, that is, sufficiently small. Therefore, it is possible to increase the maximum pressure in the cylinder without increasing the thermal stress σ _th and the mechanical stress σ _m of the bottom wall portion 1 of the cylinder head, thereby improving the output of the engine. is there. In addition, since the end of the reinforcing portion 2 is open in the state before being joined to the bottom wall portion 1, it is easy to manufacture by casting or the like, and moreover, casting defects or the like are not formed before the joining. Since it can be inspected and repaired in advance, it is possible to provide a high quality cylinder head. Further, as described above, since the bottom wall portion 1 facing the combustion chamber is made of a high-strength material having low heat conductivity and heat resistance, the mechanical and thermal strength of the bottom wall portion 1 is significantly improved. In addition to having heat insulation properties, it is possible to improve the durability and thermal efficiency of the cylinder head and thus the entire mechanism.

2 and 3 schematically show a second embodiment of the cylinder head of the present invention. This is different from the first embodiment in that a plurality of ribs 14, ..., 14 are additionally provided on the reinforcing portion 2 side in addition to the above-described reinforcing ribs 9 and the cooling water passages 13 are subdivided. ing. Since the structure of the other parts and the effect of the structure are the same as those of the first embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted. The cooling water passage 13 is particularly subdivided by the ribs 14 ... In the vicinity of the bottom wall portion 1 as shown in FIG. By subdividing the cooling water passage 13 in this way, the span distance between the ribs 9 and 14 can be further reduced, and the flow velocity of the cooling water passing through the passage 13 can be further increased to cool the cooling water. It is possible to improve the effect as well.

In each of the above-described embodiments, the flat bottom wall portion 1 is used, and the tip surfaces of the ribs 9 and 14 are butt-joined to the upper surface of the bottom wall portion 1. However, as shown in FIG. It is also possible to form a smoothly protruding protrusion 15 on the wall portion 1 and to join the end faces of the outer cylinder 8 and the ribs 9 and 14 to this protrusion 15 to improve the fatigue strength of the joint. is there.

In each of the above embodiments, the cylinder head is schematically illustrated, but in practical use, it is needless to say that a cylinder liner, a mounting portion to a cylinder block and the like are added. Is.

[0021]

[Effect of the device]

In the cylinder head of the present invention, the bottom wall portion and the reinforcing portion are formed separately, and the bottom wall portion is formed of a material having higher temperature strength and poorer heat conduction than the reinforcing portion, and these two are integrally formed. Since it is constructed by joining, it is possible to freely set the span distance of the reinforcing ribs installed in advance in the reinforcing portion.Therefore, the span of the reinforcing ribs can be made sufficiently small to reduce thermal stress and mechanical stress. It is possible to raise the maximum pressure in the cylinder without increasing it and improve the output and thermal efficiency of the engine. Furthermore, the joint surface between the bottom wall portion and the reinforcement portion is made flat over the entire surface, and the two are integrally joined in a solid state in a metallic crystal state by surface joining means such as diffusion joining. It is possible to raise the maximum cylinder pressure even in this respect. That is, in a diesel engine with a high output rate, the maximum cylinder pressure reaches 150 to 200 kg / cm ² G, the combustion temperature exceeds 2000 ° C, and the cylinder head member temperature reaches 500 ° C. The brazing method has no durability and cannot be put to practical use.However, if a solid-state bonding method such as diffusion bonding is adopted as in the present application, the entire surface can be reliably This is because sufficient bonding strength can be obtained because they can be bonded. Further, the reinforcing portion is open at one end side before joining, and therefore, when the reinforcing portion is manufactured by, for example, a casting method, the manufacturing becomes easy. ..

[Brief description of drawings]

FIG. 1 is an explanatory view of a first embodiment of a cylinder head of the present invention.

FIG. 2 is an explanatory diagram of a second embodiment.

FIG. 3 is a vertical sectional view of a main part of the above embodiment.

FIG. 4 is an explanatory diagram showing an example of changing the shape of the joint portion.

FIG. 5 is a central longitudinal sectional view showing a conventional example.

FIG. 6 is a sectional view taken along line VI-VI in the previous figure.

7 is a sectional view taken along the line VII-VII in FIG.

FIG. 8 is an explanatory diagram of an analytical model of stress acting on the cylinder head.

[Explanation of symbols]

 1 Bottom wall 2 Reinforcement 9 Reinforcement rib

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tadahiro Ozu 3-1, 1-1 Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo Kawasaki Heavy Industries Ltd. Kobe factory (72) Toshio Atsuta Toshio Atsuta Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo 3-1-1 Kawasaki Heavy Industries, Ltd. Kobe factory (72) Takeshi Yamada 3-1-1 1-1 Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo Kawasaki Heavy Industries Ltd. Kobe factory

Claims (1)

[Scope of utility model registration request] 1. A cylinder head of an internal combustion engine having a bottom wall portion facing a combustion chamber and a reinforcement portion extending from the bottom wall portion in a direction opposite to the combustion chamber, wherein the bottom wall portion and the reinforcement portion are separate bodies. In addition, the bottom wall is made of a material having higher temperature strength and poorer thermal conductivity than the reinforcing portion, and the joint surface of both is flat over the entire surface, so that the two can be joined by diffusion bonding or the like. A cylinder head for an internal combustion engine, characterized in that it is integrally joined in a solid state in a metallic crystal state by a joining means.