JPH09119341A - Cylinder head excellent in heat resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat resistance as well as to prevent crack between valves of a cylinder head by forming an exhaust port of the cylinder head by means of an aluminum casting heat resistant material. SOLUTION: An exhausts port 4 of a cylinder head main body 2 is formed of an aluminum casting heat resistant material 16, particularly, it is constituted as an aluminum casting heat resistant cast steel exhaust port. Besides the exhaust port 4 constituted of the aluminum casting heat resistant material 16, a part or the whole of a pipe on the exhaust side, namely, the fire contact surface is also constituted by being frictionally pressure-welded with a heat resistant material 3. The frictionally pressure-welded heat resistant material is extended to the outside of an exhaust valve seat 6 and an intake valve seat as necessary. Therefore, the heat resistance of the exhaust port and the fire contact surface to be exposed to the high-temperature exhaust gas is improved. Aluminum casting of the heat resistant material is performed by setting the heat resistant material in the specified position to be taken as an exhaust port of a cast mold, and casting aluminum fused liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder head, and more particularly to a cylinder head suitable for a high-power engine having improved heat resistance in the exhaust port, or between the exhaust port and the valve, and in the vicinity thereof.

[0002]

2. Description of the Related Art A cylinder head of a cylinder for an internal combustion engine is arranged above a cylinder block and constitutes a combustion chamber together with a cylinder and a piston. An exhaust valve, an injection nozzle, a spark plug, and the like are provided, and a water jacket and the like are provided inside. There are various types of combustion chambers,
There are hemispherical type and wedge type in the case of gasoline engine, and direct injection type (single chamber type) and sub-chamber type such as pre-combustion chamber in the case of diesel engine. In particular, since the combustion surface of the cylinder head is exposed to the combustion gas, there is a problem that it is heated to a high temperature during high-speed operation and cracks occur in the intervalve portion.

Conventionally, as a countermeasure, a method of improving the cooling effect from the jacket side of the cylinder head to lower the temperature of the combustion surface or a method of forming the material of the cylinder head into a casting strong against high temperature has been studied, and Prevention of cracking has been attempted. However, recently, as the output of the engine has been increased, the temperature of the combustion surface has become higher and higher, and accordingly, further improvement of the high temperature strength of the cylinder head has been demanded. In response to this demand, as a measure against the latter material, improvement in high temperature strength is attempted by adding alloy elements such as Mo and Ni to cast iron. However, since expensive alloy elements such as Mo and Ni are contained, there is a problem that the cost becomes high. Further, since the hardness of a portion other than the combustion surface which is not exposed to high temperature becomes high, the workability becomes poor, and the casting There is a problem of poor sex.

In order to solve the above-mentioned problems, for example, in Japanese Patent Laid-Open No. 59-3145, a cylinder is attached to a cylinder block to close one end of the cylinder, thereby forming a combustion chamber consisting of a closed space. In the head, a heat-resistant plate is cast on the surface facing the combustion chamber, the tip of the heat-resistant plate is extended to the outside of the line connecting the opening edge portions of the intake port and the exhaust port, and the heat-resistant plate is provided in the combustion chamber. We have proposed a cylinder head that is exposed on the surface of the cylinder head. The contents of this proposal will be described in detail with reference to the drawings. FIG. 4 is a bottom view of this proposed cylinder head. 5 is a sectional view taken along the line YY of FIG. FIG. 6 is a perspective view of the heat resistant plate.

The cylinder head 21 is cast from cast iron. The cylinder head 21 is provided with an intake port 22 and an exhaust port 23, each of which has a cavity corresponding to each cylinder. An intake valve guide 24 and an exhaust valve guide 25 that support an intake valve (not shown) and an exhaust valve (not shown) are formed in the intake port 22 and the exhaust port 23, respectively. In addition, these intake port 22 and exhaust port 23
An intake-side valve seat 26 and an exhaust-side valve seat 27 are attached to the opening edge of the lower surface facing the combustion chamber. These valve seats 26 and 27 form the valve seats of the intake valve and the exhaust valve described above. Further, a heat-resistant plate 28 is cast between the opening edge portions of the intake port 22 and the exhaust port 23, as shown in FIG. The heat-resistant plate 28 is assumed to be made of a material having excellent heat resistance such as an ordinary rolled steel plate or a heat-resistant steel plate. Steps 39 (see FIG. 5) that engage with the valve seats 26 and 27 are formed on both sides of the heat-resistant plate 28, and a small hole 40 (see FIG. 5) into which the tip of the fuel injection nozzle is inserted. 5) is formed. In FIG. 4, the circle indicated by the chain line 31 indicates the effective diameter of the cylinder.

The heat-resistant plate 28 that is cast together with the cast iron cylinder head 21 is exposed on the lower surface of the cylinder head 21. After casting, the lower surface of the cylinder head 21 is machined together with the lower surface of the heat resistant plate 28. Further, as shown by a chain line 29 in FIG. 4, the heat-resistant plate 28 has its tip extending outwardly from the line connecting the peripheral portions of the openings of the pair of intake / exhaust ports 22 and 23. The cylinder head 21 is protected in a wide range. That is, the tip portion 3 of the heat-resistant plate 28
Nos. 2 and 33 extend to positions where the heat load is low, and therefore, no thermal cracks are generated in the cylinder head 21 at the boundary between the tip ends 32 and 33 and the cylinder head 21. Head 21
It is said that it will be possible to effectively prevent damage to the. In this proposal, a heat-resistant plate is cast on the surface of the cylinder head facing the combustion chamber so as to be exposed on this surface.
Moreover, the tip of the heat-resistant plate is extended outside the line connecting the opening edge portions of the intake port and the exhaust port to prevent intervalve cracks in the cylinder head. However, since the cylinder head is made of cast iron, there is a problem in weight reduction.

Further, in Japanese Utility Model Laid-Open No. 58-167764, as shown in FIG. 7 (bottom view), a heat-resistant material is provided on the surface of the cylinder facing the combustion chamber and including the intake port and the exhaust port. We have proposed a cylinder head that is cast. The cylinder head 21 has two intake ports 22 and two exhaust ports 23. Reference numeral 38 denotes a cast heat-resistant plate, which is a proposal to prevent intervalve cracks as a heat-resistant plate extending to the outside of the intake port 22, the exhaust port 23, and the fuel injection nozzle 30. Incidentally, 31 indicates an effective diameter of the cylinder.

As described above, various proposals have been made for improving the intervalve crack resistance of the cylinder head, but the problem of insufficient heat crack resistance has not been completely solved. As a result of earnest research on prevention of intervalve cracking and diffusion of combustion heat, the inventors of the present invention have found that when manufacturing a cylinder head by casting with an aluminum alloy, an exhaust port and, if necessary, a refractory surface with a heat-resistant material are made of aluminum. A cylinder head valve that has not yet been completely solved by forming it by casting with an alloy, or by constructing the exhaust port with an aluminum casting and using a heat-resistant material, and making the fire contact surface friction-welded with a heat-resistant material. The present invention has been conceived, paying attention to the fact that it is possible to obtain a cylinder head that is excellent in heat resistance and that is capable of preventing inter-cracking, is lightweight, and has improved hot rigidity. The heat-resistant material by friction welding in the present invention is a portion including the opening edge portion on the lower surface side of the exhaust port and the intake port facing the combustion chamber of the cylinder, and also including the valve seat, and outside the combustion injection nozzle (hereinafter referred to as “ It is called the "touch surface".) An object of the present invention is to provide a cylinder head that is excellent in heat resistance as well as being lightweight.

[0009]

DISCLOSURE OF THE INVENTION The present invention is a cylinder head made of a heat-resistant material which is cast in aluminum including the exhaust port of the cylinder head and, if necessary, the touch surface. Furthermore, the present invention is a cylinder head having a structure in which the exhaust port of the cylinder head is made of a heat-resistant material by being cast in aluminum and the ignition surface is friction-welded with the heat-resistant material. The heat resistant material is heat resistant cast steel or a light alloy composite material. The cylinder head is made of aluminum alloy.

The cylinder head itself is made of aluminum to reduce the weight thereof, and the exhaust port of the cylinder head is made of a heat-resistant material by aluminum casting. Alternatively, the exhaust port of the cylinder head is made of cast aluminum and is made of a heat-resistant material, and the fire contact surface is friction-welded with a heat-resistant material to obtain a cylinder head having excellent heat resistance such as intervalve crack resistance. be able to. As the aluminum forming the cylinder itself, AC2B (Al-Cu-Si alloy system), A
C4B (Al-Si-Cu alloy system), AC4C (Al-
It is manufactured by casting with an aluminum material such as Si-Mg alloy system). In addition, in the present invention, a cylinder head made of cast iron is naturally applicable instead of the cylinder head made of aluminum although the weight is increased.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a vertical cross-sectional view of a cylinder head (including a part of a cylinder block) of the present invention in which an exhaust port is cast in aluminum and made of a heat-resistant material. Also,
FIG. 2 is a vertical cross-sectional view of a cylinder head (including a part of a cylinder block) of the present invention in which the exhaust port of the cylinder head is made of cast aluminum and is made of a heat-resistant material, and the fire surface is friction-welded to the heat-resistant material. Is. In FIG. 1, the cylinder body 2 of the cylinder head 1 is made of cast aluminum for weight reduction. The structure itself of the cylinder head 1 is the same as that described in the related art.

In the present invention, the exhaust port 4 of the cylinder head body 2 shown in FIG.
6, especially as an aluminum cast-in heat resistant cast steel exhaust port. As a result, excellent heat resistance of the exhaust port exposed to high-temperature exhaust gas can be ensured. The arrow at the tip of the fuel injection nozzle 8 in FIG. 1 indicates a state where fuel is being injected. In FIG. 1, 4 is an exhaust port, 5 is an exhaust valve, 7 is a combustion chamber, 9 is a piston, and 10 is a piston.
Is a cylinder block, 11 and 12 are water cooling jackets,
13 is a gasket. Although not shown, the aluminum cast heat resistant material 16 may be configured to include the exhaust port 4 and the fire surface. Similarly, in FIG. 2 showing the present invention, in addition to the exhaust port 4 made of the aluminum cast-in heat-resistant material 16, a structure in which the heat-resistant material 3 is friction-welded to a part or the whole of the exhaust side pipe, that is, the fire surface. And The heat-resistant material friction-welded extends to the outside of the exhaust valve seat 6 and the intake valve seat 14 (see FIG. 3). As a result, excellent heat resistance can be ensured for both the exhaust port exposed to high-temperature exhaust gas and the fired surface. In FIG. 3, 8a is a fuel injection nozzle mounting hole.

When the heat-resistant material is aluminum-encapsulated in the exhaust port portion of the aluminum cylinder head of the present invention, the heat-resistant material is set at a predetermined position to be the exhaust port of the mold, and the molten aluminum is cast (casting temperature: 670). ~ 700 ° C). In addition, in order to obtain the cylinder head of the present invention in which the exhaust port of the cylinder head is made of a heat-resistant material that is cast in aluminum and the touching surface is friction-welded with a heat-resistant material, when performing the cast-in-aluminum casting work and friction welding. As a matter of course, the work is performed in a separate process.

The friction pressure of the heat-resistant material on the fired surface of the aluminum cylinder head of the present invention is 5 to 50.
After the aluminum cylinder head and the heat resistant material are rubbed relative to each other at 15 MPa and a friction time of 25 to 50 seconds,
Upset pressure 10 to 30 MPa, upset time 3 to
Upset in 7 seconds.

As the heat resistant material applied in the present invention, a ferritic or austenitic heat resistant cast steel or a light alloy composite material is selected. As the austenitic heat-resistant cast steel, C0.15 to 0.60% by weight ratio and Si
2.0% or less, Mn 1.0% or less, Ni 8.0 to 20.
0%, Cr 15.0 to 30.0%, W 2.0 to 6.0
%, Nb 0.2 to 1.0%, B 0.001 to 0.01
%, The balance Fe and the unavoidable impurities, and a heat-resistant cast steel excellent in heat fatigue resistance is applied.

As the ferritic heat-resistant cast steel, C0.06 to 0.20% and N0.01 to 0.
10%, Si 0.4 to 2.0%, Mn 0.3 to 1.0
%, P0.04% or less, S0.04% or less, Cr15 to
A heat-resistant cast steel consisting of a basic composition of 22%, Nb 0.01 to 2.0%, balance Fe and unavoidable impurities is applied. The heat-resistant cast steel may further contain Mo 0.2 to 1.0% as a composition. In the heat-resistant cast steel of this basic composition, Ti0.
01 to 0.10%, Mo 0.2 to 1.0%, and Ni
A heat-resistant cast steel having a composition containing 0.01 to 1.0% may be used. Furthermore, in the heat resistant cast steel of this basic composition, Ti 0.01 to 0.10%, 0.2 to 1.0% M
It may be a heat-resistant cast steel having a composition containing o and 0.01 to 1.0% Ni.

Further, as a heat-resistant cast steel having a ferritic and other composition, C0.05 to 0.45 in weight ratio.
%, Si 0.4 to 2.0%, Mn 0.3 to 1.0%, C
r16.0 to 25.0%, W1.0 to 5.0%, Nb and / or V0.01 to 1.0% (each 0.5% or less), heat resistance composed of the balance Fe and unavoidable impurities Apply cast steel.

Similarly, a heat-resistant cast steel of ferritic type and having another composition, having a weight ratio of C0.15.
~ 1.20%, C-Nb / 8 is 0.05-0.45%,
Si 2% or less, Mn 2% or less, Cr 16.0 to 25.0
%, W and / or Mo 1.0 to 5.0%, Nb0.4
0-6.0%, Ni 0.1-2.0%, N 0.01-
It has a composition of 0.15%, balance Fe and unavoidable impurities, and has an α'phase transformed from the γ phase to (α + carbide) in addition to the normal α phase, and has an area ratio of α '{α' /
Heat resistant cast steel having (α + α ′)} of 20 to 70% is applied. In the present invention, the heat-resistant cast steel metal plate described above is applied, but these heat-resistant cast steels show high-temperature tensile strength, heat fatigue resistance, and oxidation resistance that are superior to those of conventional heat-resistant cast steels, and also room temperature strength. It has excellent ductility, castability, and workability, and exhibits excellent heat cracking resistance by being formed by friction welding between and near the valves of the cylinder head.

As the light alloy composite material, a fiber reinforced FRM which is an aluminum alloy reinforced with fibers such as boron, alumina and alumina-silica which have been put into practical use, or a composite material in which ceramic particles such as aluminum and SiC are dispersed. Apply.

As described above, in the present invention, the cylinder head is made of aluminum, and the exhaust port and, if necessary, the ignition surface are also made of a heat-resistant material by aluminum casting. Alternatively, the exhaust port is made of cast aluminum and made of heat-resistant material, and the fire surface is friction-welded with a heat-resistant material or light alloy composite material to extend to the outside of the intake / exhaust valve seat including the intake / exhaust port. Due to the different structure,
It is possible to obtain a cylinder head having excellent heat resistance such as intervalve crack resistance. Also, since the cylinder head itself is made of aluminum, it contributes to weight reduction.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of a cylinder head (including a part of a cylinder block) of the present invention.

FIG. 2 is a vertical sectional view of a cylinder head (including a part of a cylinder block) of the present invention.

FIG. 3 is a sectional view taken on line AA of FIG. 2;

FIG. 4 is a bottom view of a conventional cylinder head.

FIG. 5 is a view taken in the direction of arrows Y in FIG. 3;

6 is a perspective view of a heat-resistant plate cast in the cylinder head of FIG.

FIG. 7 is a bottom view of a conventional cylinder head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Cylinder head body 3 Heat-resistant material friction-welded 4 Exhaust port 5 Exhaust valve 6 Exhaust valve seat 7 Combustion chamber 8 Fuel injection nozzle 8a Fuel injection nozzle mounting hole 9 Piston 10 Cylinder block 11 Water cooling jacket 12 Water cooling jacket 13 Gasket 14 intake valve seat 15 intake port 16 aluminum cast heat resistant material 21 cylinder head 22 intake port 23 exhaust port 24 intake valve guide 25 exhaust valve guide 26 intake side valve seat 27 exhaust side valve seat 28 heat resistant plate 29 pair of intake and exhaust ports 30 A fuel injection nozzle hole 31 An effective diameter of a cylinder 32 A tip of a heat-resistant plate 33 A tip of a heat-resistant plate 38 A cast-in heat-resistant plate 39 A step 40 A fuel injection nozzle insertion hole

Claims (6)

[Claims] 1. A cylinder head, characterized in that the exhaust port of the cylinder head is made of a heat-resistant material by aluminum casting. 2. The cylinder head according to claim 1, wherein the cylinder head includes a touch surface and is made of a heat-resistant material that is cast in aluminum. 3. A cylinder head, characterized in that the exhaust port of the cylinder head is made of aluminum and is made of a heat-resistant material, and the fire surface has a structure in which a heat-resistant material is friction-welded. 4. The cylinder head according to claim 1, wherein the heat resistant material is heat resistant cast steel. 5. The cylinder head according to claim 1, wherein the heat resistant material is a light alloy composite material. 6. The cylinder head of claim 1, wherein the cylinder head is made of aluminum alloy.
The cylinder head according to any one of items.