JPH09119342A - Cylinder head excellent in crack resistance between valves - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve crack resistance between valves as well as to achieve the light weight of a cylinder head by forming the combustion surface of the cylinder head and the vicinity of it into the structure in which heat resistant materials are frictionally pressure-welded. SOLUTION: A heat resistant cast steel plate (or a light alloy composite material plate) 3 is provided on the combustion surface of a cylinder head main body 2 and the vicinity of it by frictional pressure-welding. The frictionally pressure-welded heat resistant material 3 is extended to the outside of an exhaust valve seat 6 and an intake valve seat as necessary. Manufacture of the cylinder head is performed by upsetting the aluminum cylinder head 1 and the heat resistant material 3 with the upset pressure in the range of 10 to 30MPa and in the upset time in the range of 3 to 7 minutes after they are relatively moved while rubbing them with friction pressure in the range of 5 to 15MPa and in the friction time in the range of 25 to 50 minutes. As the heat resistant material, a ferrite or austenite group heat resistant case steel or a light allay composite material is used.

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 specifically, to a cylinder suitable for a high-power engine by improving the high temperature strength of the combustion surface of the cylinder head to prevent cracks between the combustion surfaces of the valves. Regarding the head.

[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. 3 is a bottom view of the proposed cylinder head. 4 is a sectional view taken along the line YY of FIG. FIG. 5 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. 3, a circle indicated by a 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, this 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 as indicated by the chain line 29 in FIG. 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. 6 (bottom view), a heat-resistant material is provided on the surface facing the combustion chamber of the cylinder, 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.

Further, in Japanese Unexamined Patent Publication No. 61-244859, a heat-resistant metal plate for heat insulation is press-fitted into the meat of the cylinder head so as to cover a portion of the contact surface of the cylinder head where thermal cracks are likely to occur. With such a configuration, it is proposed to increase the thermal fatigue strength of the cylinder head.

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. The present inventors have earnestly studied about prevention of inter-valve cracking property and diffusion of combustion heat, and as a result of friction welding the heat resistant material to the aluminum cylinder head side between the aluminum cylinder head and the combustion chamber, it is lightweight. The present invention has been conceived, paying attention to the fact that intervalve cracks do not occur and hot rigidity can be improved. An object of the present invention is to provide a cylinder head that is excellent in intervalve crack resistance as well as being lightweight.

[0010]

SUMMARY OF THE INVENTION The present invention is a cylinder head having a structure in which a combustion surface of the cylinder head and its vicinity are friction-welded with a heat resistant material. The heat resistant material is heat resistant cast steel. The heat resistant material is a light alloy composite material.

By making the cylinder head itself of aluminum to reduce the weight and joining the heat-resistant material by friction welding, a cylinder head having excellent intervalve crack resistance can be obtained. As aluminum, AC2B (Al-Cu-
Si alloy system), AC4B (Al-Si-Cu alloy system),
It is manufactured by casting using an aluminum material such as AC4C (Al-Si-Mg alloy system).

[0012]

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.
2 is a partial sectional view taken along the line AA of FIG. FIG.
In the above, the cylinder body 2 of the cylinder head 1 is made of cast aluminum, which is lightweight. The structure itself of the cylinder head 1 is the same as that described in the related art. In the present invention, the heat-resistant cast steel plate or the light alloy composite material plate is formed on the combustion surface of the cylinder head body 2 shown in FIG. 1 and its vicinity by using friction welding. The heat-resistant material frictionally welded is extended to the outside of the exhaust valve seat 6 and the intake valve seat 14 (see FIG. 2). 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, 10 is a cylinder block, 11 and 12 are water cooling jackets, and 13 is a gasket. Further, in FIG. 2, 8a is a nozzle mounting hole.

In order to obtain the cylinder head of the present invention, after the aluminum cylinder head and the heat-resistant material are rubbed relative to each other at a friction pressure of 5 to 15 MPa and a friction time of 25 to 50 seconds, the upset pressure is 10 to 30 MPa. Upset is performed with an upset time of 3 to 7 seconds.

In the present invention, a ferritic or austenitic heat-resistant cast steel or a light alloy composite plate is formed by friction welding at the site where intervalvular cracking occurs due to thermal fatigue. As the austenitic heat-resistant cast steel, C0.15 to 0.60%, Si2.0% or less, and Mn in weight ratio.
1.0% or less, Ni 8.0 to 20.0%, Cr 15.0
.About.30.0%, W2.0 to 6.0%, Nb0.2 to 1.
A heat-resistant cast steel having a composition of 0%, B 0.001 to 0.01%, the balance Fe and unavoidable impurities and having excellent heat fatigue resistance is applied.

As for 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, the weight ratio is C0.05 to 0.45.
%, 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 further have 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 combustion surface of the cylinder head and its vicinity are absorbed by the heat resistant material plate by friction welding.
With the structure including the exhaust port and extending to the outside of the intake / exhaust valve seat, it is possible to obtain a cylinder head with excellent intervalve crack resistance and contribute 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 sectional view taken along the line AA of FIG.

FIG. 3 is a bottom view of a conventional cylinder head.

FIG. 4 is a view taken in the direction of arrows YY in FIG. 3;

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

FIG. 6 is a bottom view of a conventional cylinder head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Cylinder head main 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 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 Chain line 30 Fuel injection nozzle hole 31 Effective diameter of cylinder 32 Tip of heat-resistant plate 33 Tip of heat-resistant plate 38 Cast heat-resistant plate 39 Step 40 Fuel-injection nozzle insertion hole

Claims (3)

[Claims] 1. A cylinder head having a structure in which a combustion-resistant surface of the cylinder head and its vicinity are friction-welded with a heat-resistant material. 2. The cylinder head according to claim 1, wherein the heat resistant material is heat resistant cast steel. 3. The cylinder head according to claim 1, wherein the heat resistant material is a light alloy composite material.