JP3555431B2 - Structure of heat shield type engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a structure of a heat shield type engine comprising a ceramic port liner provided with a heat shield layer provided on a cylinder head.
[0002]
[Prior art]
In a normal engine cylinder head, the surface facing the combustion chamber and the mounting surface on which the intake manifold and exhaust manifold are mounted do not form the same surface, and the mounting surface is almost perpendicular to the surface facing the combustion chamber. Is formed. Therefore, in order to configure the port provided in the cylinder head as a heat shield structure, a port liner made of ceramics is manufactured in advance, and when the cylinder head is manufactured by casting from a metal material such as an aluminum alloy or Fc, the port liner is formed. And a port liner is arranged in the cylinder head by casting.
[0003]
However, when a port liner made of a low thermal conductive material such as aluminum titanate is cast into a metal material, a high compressive stress acts on the port liner due to a compressive force caused by shrinkage after casting into a metal material of Al or Fc. The port liner may be damaged by the compressive stress. Therefore, as a measure to prevent the port liner from being damaged due to shrinkage after casting, it is conceivable to wind the outer periphery of the port liner with a material such as alumina fiber. For example, a manufacturing method of forming an intake / exhaust port in a cylinder head is to form a heat insulating structure by piercing a ceramic port liner at the time of casting the cylinder head. In order to prevent the port liner from being damaged by compressive stress due to the contraction force of the metal material, a buffer layer is provided between the cylinder head and the port liner, and the port liner is manufactured by casting.
[0004]
The ceramic port liner disclosed in Japanese Patent Application Laid-Open No. 8-150463 prevents damage to the ceramic port liner due to contraction of metal during casting of the cylinder head, and encloses a stress buffer layer contained therein. is there. In the ceramic port liner, a shell is made of a port liner made of ceramics and a plate material, and the outer surface of the port liner is covered with a stress buffer layer made of a buffer material. Make a core by covering the shell with a shell, closing the openings at both ends of the port liner with plugs, placing the core in a cylinder head mold, casting the molten metal, and exposing the stress buffer layer that constitutes the heat shield layer The cylinder head is manufactured by cutting the open end surface of the outer shell and casting a port liner.
[0005]
[Problems to be solved by the invention]
By the way, the structure of the ceramic engine prevents the heat flow from dissipating to the outside by the heat shielding structure of the combustion chamber member, which is the main chamber, and the piston head. However, the combustion chamber member is provided between the intake manifold and the exhaust manifold. And an intake port and an exhaust port formed in the cylinder head that communicates with each other. However, for large engines mounted on large trucks, cast iron is mainly used for cylinder heads. Therefore, since the intake port and the exhaust port of the large cast iron cylinder head are configured to have a heat shielding structure, there is a problem that when the cylinder head is manufactured by casting the cast iron, the ceramic port liner cannot be arranged and manufactured. . That is, while the temperature of the molten iron of cast iron is about 1450 ° C. to 1500 ° C., the heat resistant temperature of Si ₃ N ₄ is about 1150 to 1200 ° C., the heat resistant temperature of alumina and Al ₂ O ₃ is about 900 ° C. The heat-resistant temperature is about 1400 to 1500 ° C, and the temperature of exhaust gas emitted from the engine is about 900 ° C. Therefore, various heat-resistant ceramics are thermally damaged at the temperature of the molten cast iron, and it is difficult to manufacture the port liner with ceramics.
[0006]
Also, when a bent port is formed in the cylinder head, the manifold communicating with the port is mounted on the cylinder head, making it difficult to form a flat cylinder head mounting surface, increasing the manufacturing cost. It was not always a preferred manufacturing method.
[0007]
Also, in the case where a buffer layer is provided between the cylinder head and the port liner and casting is performed, the joint processing and the end surface treatment are performed so that the molten metal material during casting does not flow into the alumina fiber part. And so on, which makes the process complicated, and there is a problem that mass production including dimensional tolerances cannot be performed. Also, a buffer layer such as alumina fiber is exposed at the end face of the cylinder head, and a part of the buffer layer falls off, resulting in deterioration of the performance of the heat shield layer and rattling of the ceramic port liner, leading to damage. There is.
[0008]
[Means for Solving the Problems]
An object of the present invention is to solve the above-mentioned problems by preparing a port liner made of ceramics in advance, casting a cylinder head into a shape having a straight port, and then manufacturing the ceramic head in the port in advance. An object of the present invention is to provide a structure of a heat shield type engine in which a port liner is inserted and arranged at a predetermined position so that the ceramic port liner is not thermally affected by casting.
[0009]
The present invention relates to a cylinder head made of metal formed by casting and having a straight port, a combustion chamber member provided to face the cylinder head, and having a combustion chamber and a port opened to the combustion chamber by a valve. A port liner made of heat-resistant ceramics, which is inserted into the port of the cylinder head so as to communicate with the port of the combustion chamber member and extends straight at a predetermined angle and extends straight; The present invention relates to a structure of a heat shield type engine comprising a heat shield layer formed between the cylinder head and the port, and gaskets disposed at both ends of the port liner.
[0010]
In the structure of the heat shield type engine, an outlet opening surface of the port formed in the cylinder head is formed on a surface inclined with respect to a lower surface of the cylinder head, and the port liner inserted into the port is provided with the port liner. It is arranged to communicate with the port formed in the combustion chamber member.
[0011]
A reinforcing member made of metal, ceramic fiber, or carbon fiber coated with ceramic is provided on an outer periphery of the port liner inserted into at least one of the ports on the exhaust side. The ceramic forming the port liner has a low thermal conductivity, but has a low strength. Therefore, the outside thereof may be reinforced with a reinforcing material to reinforce the strength of the port liner.
[0012]
A reinforcing pipe made of a metal double pipe is provided on an outer periphery of the port liner inserted into at least the exhaust port of the ports. Further, the hollow portion of the double pipe of the reinforcing pipe is substantially evacuated, and a support member for maintaining the shape is disposed in the hollow portion of the double pipe. That is, since the port liner is formed straight, a metal double tube whose inside is evacuated can be arranged outside the port liner, so that the port liner can be reinforced and the heat shielding property can be improved. .
[0013]
The gasket is formed of a ceramic fiber gasket. Further, a gasket made of ceramic fiber is arranged in a region of a valve hole formed in the port liner through which a valve formed in the port liner passes.
[0014]
The port liner may have a two-part structure. If the port liner is divided, the port liner can be easily inserted into the port of the cylinder head. However, the port liner needs to be configured to prevent gas leakage.
[0015]
The structure of this heat shield type engine is such that the combustion chamber member is arranged through a heat shield layer in a hole of a spacer arranged between the cylinder head and a cylinder block attached to the cylinder head. The chamber member has a port formed by the port liner and a port communicating the combustion chamber, and a valve seat on which a valve for opening and closing the port is disposed.
[0016]
The structure of this heat shield type engine allows the cylinder head to be manufactured without placing a ceramic port liner when casting the cylinder head, and then the ceramic port liner is placed in the port formed by casting in the cylinder head. In addition, the port liner is not thermally affected by the molten metal at the time of casting, and no thermal damage occurs during casting at the port liner. Therefore, the ceramic port liner arranged in the cylinder head can be constructed with high durability. In addition, in the present invention, the port formed in the cylinder head is not formed in a bent shape as in the prior art, but is formed in a straight shape, so that a straight ceramic port liner can be easily inserted into the straight port. If the fiber gasket is arranged at both ends of the ceramic port liner, the fiber gasket can absorb the pressure difference generated in the port when the engine is operating, thereby damping the ceramic port liner. It is possible to prevent damage due to the pressure difference of the ceramic port liner.
[0017]
The conventional heat shield type engine has a structure in which the combustion chamber has a mounting part on the horizontal surface, and the port liner and the manifold communicate with each other vertically. In the structure of the heat shield type engine according to the present invention, as described above, the outlet-side opening surface of the port formed in the cylinder head is formed on a surface inclined with respect to the lower surface of the cylinder head. The port liner can be securely attached to the cylinder head.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the structure of a heat shield type engine according to the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the structure of the heat shield type engine according to the present invention, and FIG. 2 is a sectional view showing another embodiment of the port liner applied to the structure of the heat shield type engine of FIG. is there.
[0019]
As shown in FIG. 1, the structure of a heat shield type engine according to the present invention can be applied to a heat shield type engine such as a diesel engine, a gas engine, a gasoline engine and the like. However, it can also be applied to a type with a main chamber and a sub chamber as a combustion chamber. The heat shield type engine mainly fits into the cylinder block 14, the cylinder head 3 fixed to the upper surface of the cylinder block 14 through the gaskets 29 and 36, and the cylinder spacer 15, and the hole 24 formed in the cylinder block 14. A cylinder liner 26 constituting the cylinder 25, a combustion chamber member 10 disposed in a hole 37 of a cylinder spacer 15 constituting a part of the cylinder head 3, and a piston 20 reciprocating in the cylinder 25 formed in the cylinder liner 26. have. The end of the port 7 formed in the cylinder head 3 on the side facing the combustion chamber member 10 extends horizontally, and the end on the side facing the exhaust manifold 16 and the intake manifold 18 has an inclined surface 42. Is formed. An exhaust port liner 17 is formed on an inner surface of the exhaust manifold 16 so as to form an air layer 43, and an intake port liner 19 is formed on an inner surface of the intake manifold 18 so as to form an air layer 44.
[0020]
The combustion chamber member 10 is formed from a heat-resistant material such as a ceramic such as Si ₃ N ₄ or a heat-resistant alloy. The combustion chamber member 10 includes a head liner including a head lower surface portion 28 and a liner upper portion 27 integrally formed therewith. The combustion chamber member 10 forms a heat shield air layer 13 between the outer peripheral surface of the cylinder spacer 15 located between the cylinder head 3 and the cylinder block 14 and the hole 37 formed in the cylinder spacer 15. The combustion chamber 23 is arranged in the hole 37 of the cylinder spacer 15 with the gasket 38 interposed therebetween, and the combustion chamber 23 is configured as a heat shield structure. Ports 5 and 6 and a combustion chamber 23 are formed in the lower surface portion 28 of the head of the combustion chamber member 10.
[0021]
In one port 7 formed in the cylinder head 3, a ceramic port liner 1 forming an exhaust port 8 is disposed so as to form a heat shielding air layer 40, and in the other port 7, an intake port is formed. The ceramic port liner 2 forming 9 forms a thermal barrier air layer 40. The port 5 communicates with an exhaust port 8 formed in the port liner 1. The port 6 communicates with an intake port 9 formed in the port liner 2. A reinforcing member 4 is wound around the outer periphery of the exhaust port liner 1. An exhaust-side port 5 and an intake-side port 6 are formed in the head lower surface portion 28 of the combustion chamber member 10.
[0022]
An exhaust valve 11 is disposed on a valve seat 51 provided at the port 5 of the combustion chamber member 10, and an intake valve 12 is disposed on the valve seat 51 provided at the port 6. A valve spring retainer 41 is fixed to the upper part of the exhaust valve 11 and the intake valve 12 by a cotter, and a valve spring 32 is disposed between the valve spring retainer 41 and the upper surface of the cylinder head 3. The mechanism is guided by a valve guide 31 provided on the cylinder head 3 so as to be vertically movable.
[0023]
The piston 20 includes a piston head 21 formed of a heat-resistant material such as ceramics such as Si ₃ N ₄ or a heat-resistant alloy, and a piston skirt 22 fixed to the piston head 21 and formed of a metal material such as an Al alloy. ing. A gasket 33 is interposed between the piston head 21 and the piston skirt 22 to form a heat shield air layer 34. The piston head 21 and the piston skirt 22 are fixed by a connecting ring 35 by metal flow or the like. The combustion chamber 23 is formed on the lower surface 39 of the head lower surface portion 28 of the combustion chamber member 10, a region surrounded by the cylinder 25 formed by the cylinder liner 26 and the liner upper portion 27, and the upper surface of the piston head 21, and on the upper surface. It is formed by a recess.
[0024]
The structure of this heat shield type engine is manufactured by casting a cylinder head 3 made of a metal such as cast iron, aluminum, or an alloy thereof so as to form a straight port 7. In the port 7 of the cylinder head 3, straight ceramic port liners 1 and 2 are arranged so as to form a heat shielding air layer 40. The ceramic port liners 1 and 2 are made of heat-resistant ceramic and are inserted into the ports 7 of the cylinder head 3. The ceramic port liners 1 and 2 are inserted to extend straight at a predetermined inclination angle so as to communicate with the ports 5 and 6 of the combustion chamber member 10, respectively. That is, the outlet side openings of the exhaust manifold 16 and the intake manifold 18 of the port 7 formed in the cylinder head 3 are formed on the inclined surface 42 inclined with respect to the lower surface 45 of the cylinder head 3, and the port 7 is provided in the combustion chamber. It extends straight in an inclined state so as to communicate with ports 5 and 6 formed in the member 10.
[0025]
A heat shield layer 40 is formed between the port liners 1 and 2 and the port 7 of the cylinder head 3, and between one end of the port liners 1 and 2 and the combustion chamber member 10 and between the port liners 1 and 2. A fiber gasket 30 is disposed between the other end of the gasket and the exhaust manifold 16 and the intake manifold 18. The fiber gasket 30 is formed of a ceramic fiber gasket such as heat-resistant alumina fiber, alumina whisker, and alumina long fiber. A ceramic fiber gasket 30 is arranged in a valve hole 50 formed in the port liners 1 and 2 through which the intake valve 12 and the exhaust valve 11 pass. A reinforcing member 4 made of ceramic fiber or carbon fiber coated with ceramic is provided on at least the outer periphery of the port liner 1 inserted into the exhaust port 8 of the ports 7.
[0026]
Next, another embodiment of the structure of the heat shield type engine according to the present invention will be described with reference to FIG. First, the port liner 2 can be configured to have a structure in which a reinforcing pipe 46 composed of a metal double pipe 47 is provided on the outer periphery thereof. The hollow portion 49 of the double pipe 47 of the reinforcing pipe 46 is substantially evacuated, and a corrugated support member 48 for maintaining the shape is disposed in the hollow portion 49 of the double pipe 49. In this case, the double tube 49 and the convex portion of the support member 48 are only in local contact, and a sufficient heat shield layer can be formed by the vacuum layer of the hollow portion 49.
[0027]
Alternatively, the structure of the heat shield type engine is not shown, but the port liner may be configured in a split structure. When the port liner has a two-part structure, the cylinder head 3 can be easily inserted into the port 7. Alternatively, when the port 7 is formed to have a bent shape in the cylinder head 3, the openings on both sides, that is, the openings on the combustion chamber member 10 side, the intake manifold 18 side, and the exhaust manifold are formed in the cylinder head 3. It is also possible to configure so that a straight port liner can be inserted from the opening on the 16 side.
[0028]
【The invention's effect】
In the structure of the heat shield type engine according to the present invention, the cylinder head and the port liner are manufactured in separate processes, and then the port liner is inserted into the port of the cylinder head to form the exhaust port liner and the intake port liner. The port liner is not affected by the heat during the casting of the cylinder head, and the port liner is free from cracks and cracks, and a highly durable heat shield type engine can be manufactured. In addition, the structure of this heat shield type engine can provide a good heat shield structure, so that heat dissipation in the cylinder head area can be suppressed, and exhaust gas is supplied to the turbocharger and engine recovery device provided downstream of the port liner. The heat energy can be sufficiently recovered by feeding. Further, since heat-resistant gaskets are disposed at both ends of the port liner, the port liner is buffered against changes in pressure inside and outside of the port liner, so that the port liner is not damaged.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of the structure of a heat shield type engine according to the present invention.
FIG. 2 is a sectional view showing another embodiment of the port liner applied to the structure of the heat shield type engine of FIG. 1;
[Explanation of symbols]
1, 2 port liner 3 cylinder head 4 reinforcing material 5, 6, 7 port 8 exhaust port 9 intake port 10 combustion chamber member 11, 12 valve 13 heat shielding air layer 14 cylinder block 15 cylinder spacer 23 combustion chamber 30 fiber gasket 37 Hole 40 Heat shielding air layer 42 Inclined surface 45 Cylinder head lower surface 46 Reinforcement pipe 47 Double tube 48 Support member 49 Hollow portion 50 Valve hole 51 Valve seat

Claims (9)

A cylinder head made of metal produced by casting and having a straight port, a combustion chamber member disposed opposite to the cylinder head and having a combustion chamber and a port opened to the combustion chamber by a valve, and the combustion chamber A port liner made of a heat-resistant ceramic, which is inserted into the port of the cylinder head so as to communicate with the port of the member and which extends straight at a predetermined angle and is inclined between the port liner and the cylinder head; A structure of a heat shield type engine comprising: a heat shield layer formed between the port liner; and gaskets disposed at both ends of the port liner. An outlet-side opening surface of the port formed in the cylinder head is formed on a surface inclined with respect to a lower surface of the cylinder head, and the port liner inserted in the port is formed in the combustion chamber member. 2. The structure of a heat-shielded engine according to claim 1, wherein the structure is arranged so as to communicate with the engine. The reinforcing member made of metal, ceramic fiber, or carbon fiber coated with ceramic is provided on an outer periphery of the port liner inserted into at least one of the ports on the exhaust side among the ports. The structure of the heat shield type engine. 2. The structure of the heat shield type engine according to claim 1, wherein a reinforcing pipe made of a metal double pipe is provided on an outer periphery of the port liner inserted into at least one of the ports on the exhaust side of the ports. . 5. The reinforcing pipe according to claim 4, wherein the hollow portion of the double tube of the reinforcing pipe is substantially evacuated, and a support member for maintaining the shape is disposed in the hollow portion of the double tube. The structure of the heat shield type engine. The structure of a heat shield type engine according to any one of claims 1 to 5, wherein the gasket comprises a ceramic fiber gasket. 7. The gasket according to claim 1, wherein a ceramic fiber gasket is disposed in a region of a valve hole formed in the port liner through which a valve formed in the port liner passes. The structure of the heat shield type engine. The structure of the heat shield type engine according to any one of claims 1 to 7, wherein the port liner has a split structure. The combustion chamber member is disposed in a hole portion of a spacer disposed between the cylinder head and a cylinder block attached to the cylinder head via a heat shield layer, and the combustion chamber member is formed of the port liner. The heat shield type according to any one of claims 1 to 8, further comprising a port that communicates the port to be connected with the combustion chamber, and a valve seat on which a valve that opens and closes the port is disposed. Engine structure.

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