JPH0689711B2 - Adiabatic engine structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to the structure of a heat insulating engine in a ceramic engine or the like.

[Conventional technology]

Conventionally, an engine member such as a heat insulating engine using a ceramic material as a heat insulating material or a heat resistant material is disclosed in, for example, JP-A-60-
It is disclosed in Japanese Patent Publication No. 90955. The structure of the heat insulation engine disclosed in Japanese Patent Laid-Open No. 60-90955 will be outlined with reference to FIG. In FIG. 2, the structure of the adiabatic engine is indicated generally by the numeral 30. In this heat insulating engine structure 30, a heat reflecting surface is formed on a circumferential wall 33 of a cylindrical portion 32 provided in the lower half of the cylinder head 31, and a reverse cup-shaped headliner made of ceramics is formed on the cylindrical portion 32 of the cylinder head 31. 34 is fitted with an empty portion 35 provided around this. A heat insulating material 36 such as a ceramic fiber or a glass fiber is housed in a space 35 between the cylinder portion of the cylinder head 31 and the head liner 34. Further, the upper end wall 41 of the headliner 34 is attached to the inner end wall 33 of the cylindrical portion 32 of the cylinder head 31 through the gasket 43, and the headliner
The lower end wall of 34 is pressed against the upper ends of the cylinder block 37 and the cylinder liner 39 via the elastic gasket 44, respectively, to alleviate stress concentration in the headliner 34 due to imbalance of tightening force and thermal deformation. Since the void portion 35 is formed, the headliner 34 that surrounds the combustion chamber 40 to the cylinder 31
The heat conduction to is blocked, and the heat dissipation can be suppressed. Further, heat radiation is reflected by the heat reflecting surface of the inner end wall 33, and heat transfer to the cylinder head 31 can be suppressed. Further, a heat insulating material 36 such as ceramics fiber is provided in the empty space 35.
By containing the above, it is possible to prevent convection of air in the vacant portion 35 and suppress heat transfer from the wall portion of the headliner 34 to the cylinder head 31. Therefore, it is possible to suppress the heat of the combustion chamber 40 from being dissipated from the headliner 34 to the outside, so that the exhaust gas can be sent to the exhaust turbocharger or the like through the exhaust passage in a high temperature state. It is possible to make maximum use of the heat energy of the. In the figure, reference numeral 38 indicates a piston.

[Problems to be solved by the invention]

However, it is extremely difficult to obtain sufficient heat insulating properties in a heat insulating engine member such as a cylinder head that uses the above ceramics as a heat insulating material or a heat resistant material, and the wall thickness increases in order to obtain sufficient heat insulating characteristics. There is a problem. That is, the part of the engine facing the combustion chamber is made of silicon nitride ceramics, which has excellent heat resistance, heat insulation, and heat shock resistance, and can withstand high-temperature combustion gas. Becomes too big,
There is a problem that inhalation efficiency is reduced.

By the way, regarding the structure of the heat insulation engine disclosed in the above-mentioned JP-A-60-90955, the upper end wall of the headliner 34 is
41 is the cylindrical portion 32 of the cylinder head 31 through the gasket 43.
The inner end wall 33, and the lower end wall of the head liner 34 is pressed against the upper ends of the cylinder block 37 and the cylinder liner 39 via an elastic gasket 44, respectively.
Since the vacant portion 35 is formed between the headliner 34 and the cylinder head 31, it is not always possible to obtain a heat insulating structure with excellent pressure resistance, and there are problems, and at the same time high temperatures are encountered. It does not have the technical idea of reducing the heat capacity of the exposed portion, and has the same problems as above.

An object of the present invention is to eliminate the above-mentioned problems, and the thickness of the cylinder head liner is configured to be as thin as possible, and the heat capacity of the cylinder head liner facing the combustion chamber and having a high temperature is configured to be small. Therefore, it is an object of the present invention to provide a structure of an adiabatic engine which improves the intake efficiency of the engine and also improves the strength deterioration due to the reduction of the wall thickness.

[Means for solving problems]

The present invention is configured as follows in order to solve the above problems and achieve the above objects. That is, the present invention relates to a structure of a heat insulating engine characterized in that a heat insulating sheet is arranged on the outer surface of a cylinder head liner made of ceramics, and a metal material is cast around the outer surface of the heat insulating sheet. More specifically, in order to reduce the heat capacity of the cylinder head liner, the cylinder head liner has a thin wall thickness, and an air layer is formed on the heat insulating sheet, and the heat insulating sheet is formed by laminating titanic acid paper. Or a heat-insulated engine characterized by being formed integrally by mixing potassium titanate whiskers with an organic binder, or by mixing potassium titanate whiskers, alumina fibers and an organic binder and molding. Concerning the structure of.

[Action]

The structure of the heat insulation engine according to the present invention is configured as described above, and operates as follows. That is, in the structure of this heat insulating engine, since the heat insulating sheet is arranged on the outer surface of the cylinder head liner made of ceramics, and the metal material is arranged around the outer surface of the heat insulating sheet, it is exposed to high temperature combustion gas. The wall thickness of the cylinder head liner and the cylinder liner can be made thin, the heat capacity can be made small, and therefore, the intake efficiency of the engine can be improved, and at the time of cooling after the cast metal is cast, the metal material can be cooled. Shrinks, the cylinder head liner made of ceramic is compressed, the heat insulating fiber serves as a cushioning material, and the heat insulating sheet receives a compressive force and is fixedly held,
Then, the cylinder head 1 is configured such that the metal material 2 exerts a compressive force on the cylinder head liner 3. At the same time, the outer peripheral surface of the cylinder head liner made of ceramics is configured to exert a compressive force, and therefore, a structure having excellent pressure resistance can be configured, and further, the heat insulating sheet containing potassium titanate as a main component is used. Therefore, excellent heat insulating properties can be obtained, and more excellent heat insulating effect can be obtained by the air layer formed on the heat insulating sheet. As described above, in order to improve the intake efficiency of the engine, it is important to minimize the heat capacity of the ceramic inner wall that becomes high temperature in order to minimize the heat received from the inner wall of the cylinder of the adiabatic engine. By reducing the heat capacity, the wall surface immediately cools during intake air, and the temperature difference between the intake air temperature and the wall surface temperature is reduced, thereby facilitating inflow of intake air. Also, at the maximum temperature in the combustion chamber, the amount of heat absorbed by the wall surface is reduced to reduce the temperature difference between the combustion gas temperature and the wall surface temperature, and the thermal energy that escapes to the outside through the cylinder head, cylinder block, etc. is minimized. .

〔Example〕

Hereinafter, embodiments of the structure of the heat insulation engine according to the present invention will be described in detail with reference to the drawings.

In FIG. 1, the structure of an adiabatic engine, which is an embodiment of the present invention, is generally indicated by reference numeral 10. Regarding the structure 10 of this heat insulating engine, only the technical idea of the heat insulating structure of the cylinder head in the heat insulating engine is disclosed, and the cylinder 12 other than the above,
Although the heat insulating structure for the piston 8 and the intake / exhaust valve 9 is not disclosed, that is, not shown, for the heat insulating engine, the cylinder, the piston, and the intake / exhaust valve are also made of silicon nitride ceramics, a heat insulating sealing material, or the like. Needless to say, the object can be achieved more reliably by using the heat insulating structure. As a general structure,
Inside the cylinder 12, a piston 8 including a piston head 13 and a piston skirt 14 is configured to reciprocate. An intake / exhaust port 11 is formed in the cylinder head 1, and the intake / exhaust port 11 is configured to be opened / closed by an intake / exhaust valve 9. The thickness of the cylinder head liner 3 in the cylinder head liner 1 is formed to be as thin as possible, and the outer surface of the cylinder head liner 3 is covered with a heat insulating sheet 4 having excellent heat insulating properties and pressure resistance. In the structure 10 of this heat insulation engine, the cylinder head 1 has a heat insulation sheet 4 which is titanate coated paper containing potassium titanate or the like as a main component on the outer surface of a cylinder head liner 3 made of ceramics such as silicon nitride. A metal material 2 such as an aluminum alloy is arranged around the outer surface of the heat insulating sheet 4 by casting. Metal material 2
By constructing the cylinder head 1 by casting, the heat insulating fiber serves as a buffer material to compress the ceramic cylinder head liner, which contracts when cast into metal, but is fixed and held by the compression force. It Then, the cylinder head 1 is configured such that the metal material 2 exerts a compressive force on the cylinder head liner 3. The ceramic cylinder head liner 3 is exposed to the high temperature combustion gas in the combustion chamber 5 of the engine, and the thickness of the cylinder head liner 3 is set to minimize heat reception from the inner wall of the combustion chamber 5. Is configured as thin as possible to reduce the heat capacity of the cylinder head liner 3. Further, in order to prevent the strength from being deteriorated by making the cylinder head liner 3 thin, the cylinder head liner 3 is provided on the outer peripheral portion with a heat insulating sheet 4.
It reinforces the strength and improves heat insulation. Further, a gasket 7 is interposed between the cylinder head 1 and the cylinder liner 12. Further, around the intake / exhaust port 11 of the cylinder head 1, a heat insulating gasket 6 in which potassium titanate or the like is coated with a metal material is provided, and a heat insulating sheet 4 is provided between the metal material 2 and the cylinder head liner 3. It prevents it from leaking. An air layer is formed in the heat insulating sheet 4, and this air layer has a further heat insulating effect. Heat insulation sheet 4
For the structure of, for example, laminated titanate paper, potassium titanate whiskers mixed with organic binder and integrally molded, or potassium titanate whiskers, aluminum fiber and organic binder mixed and molded. There are things. Regarding potassium titanate, for example, whisker-like potassium titanate (K ₂ Ti
₆ O ₁₃ , melting point 1370 ° C, specific gravity 3.2, thermal conductivity 0.00012 cal / cm
sec ° C). The thermal conductivity of the silicon nitride ceramics is 0.04 Cal / cm sec ° C, and the thermal conductivity of the ceramic sheet that is the heat insulating sheet 4 impregnated with potassium titanate is 0.0002 Cal / cm sec ° C. is there.

Various examples of these heat insulating sheets 4 will be described in detail. First, the heat insulating sheet 4 of one example is formed by laminating a ceramic sheet impregnated with potassium titanate. Another example of the heat insulating sheet 4 is a stack of sheets formed into a paper form by mixing potassium titanate whiskers as a main component with an organic binder. Further, as another example of the heat insulating sheet 4, a sheet formed by mixing an organic binder containing potassium titanate whiskers as a main component into a paper shape and laminating sheets reinforced by sandwiching the upper and lower surfaces with alumina fiber sheets is laminated. . Further, as still another example of the heat insulating sheet 4, an alumina fiber which is a short fiber of alumina containing potassium titanate whiskers as a main component and an organic binder are mixed and molded into a cup shape.
Although potassium titanate whiskers are used in the above example, it is needless to say that ceramic fibers such as zirconia fibers may be used instead of potassium titanate whiskers.

The structure 10 of the adiabatic engine according to the present invention is configured as described above, and can be manufactured, for example, as follows. A cylinder head liner 3 formed by integrally forming a cylinder head lower surface and a cylinder liner upper portion made of silicon nitride ceramics or the like is configured to have a wall thickness of about 2 to 3 mm, and a titanium acid molding is performed on an outer peripheral portion of the cylinder head liner 3. A heat insulating sheet 4 formed into a cup shape by a heat insulating material mainly composed of ceramic fibers such as paper, titanic acid coated paper, non-combustible paper, etc. is provided. After the cylinder head liner 3 and the heat insulating sheet 4 are integrated by an appropriate means, the integrally formed body is cast together with the metal material 2 such as an aluminum alloy, thereby forming the formed body around the metal material 2. . However, the aluminum alloy used for the cast metal is cooled after the cast metal, but the aluminum alloy shrinks during the cooling. Therefore, the heat insulating sheet 4 receives the compressive force and is fixed, and at the same time, the compressive force acts on the ceramic wall surface of the cylinder head liner 3. By the way, during combustion of the engine, high pressure is generated in the combustion chamber 5 by the combustion gas. Therefore, due to the high pressure of the combustion gas, a compressive force acts on the ceramics inner peripheral surface of the cylinder head liner 3, which is the wall surface of the combustion chamber. However, since the structure of the adiabatic engine according to the present invention is configured as described above, it is possible to withstand the high pressure at the time of engine combustion,
At the same time, it can exhibit high heat insulation even at high temperatures. That is,
With respect to the structure of the heat insulation engine according to the present invention, the heat insulation sheet 4 can exhibit high heat insulation.

〔The invention's effect〕

Since the structure of the heat insulation engine according to the present invention is configured as described above, it has the following effects. That is, in the structure of this heat insulating engine, since the heat insulating sheet is arranged on the outer surface of the cylinder head liner made of ceramics, and the metal material is arranged around the outer surface of the heat insulating sheet, it is exposed to high temperature combustion gas. The wall thickness of the cylinder head liner can be configured to be as thin as possible, the heat capacity can be reduced, and therefore the engine intake efficiency can be improved, and at the time of cooling after the cast metal is cast, the metal material can be Because of the shrinkage, the heat insulating sheet is fixed by receiving a compressive force, and at the same time, the outer peripheral surface of the cylinder head liner made of ceramics is made to exert a compressive force, so that a structure having excellent pressure resistance can be configured. In addition, since the heat insulating sheet containing potassium titanate as a main component is used, excellent heat insulating property can be obtained, and the heat insulating sheet can be obtained. It is possible to obtain a more excellent thermal insulation effect by the air layer formed. As described above, in order to improve the intake efficiency of the engine, it is important to minimize the heat capacity of the ceramic inner wall that becomes hot in order to minimize the heat received from the inner wall of the cylinder of the adiabatic engine. Is. The reason is that by reducing the heat capacity, the wall surface immediately cools at the time of intake air, and the temperature difference between the intake air temperature and the wall surface temperature is reduced, thereby facilitating the inflow of intake air. Also, at the time of the maximum temperature in the cylinder, the amount of heat absorbed by the wall surface is reduced to reduce the temperature difference between the combustion gas temperature and the wall surface temperature, and the thermal energy escaping to the outside through the cylinder head and the cylinder block is minimized. With this configuration, the intake efficiency of the engine can be improved, and the thermal energy in the combustion chamber can be sent to the energy recovery device provided downstream through the exhaust port, thus maximizing the thermal energy. Can be collected. For example, in an adiabatic engine, by configuring the heat capacity of the portion in contact with high-temperature gas, that is, the cylinder headliner to be small, thermal energy is not retained in the cylinder headliner during the explosion process and exhaust process of the engine, In other words,
Most of the thermal energy can be sent to the energy recovery device provided downstream via the exhaust port without the thermal energy remaining in the combustion chamber. Also,
In the intake process of the engine, the portion of the cylinder head liner that is in contact with the high temperature gas, that is, the cylinder head liner, has a small heat capacity, so it is immediately cooled to an appropriate temperature, and intake air is not blocked from flowing into the combustion chamber. The phenomenon that the inhalation efficiency is lowered does not occur. That is, by reducing the heat capacity, the wall surface immediately cools during intake air, and the temperature difference between the intake air temperature and the wall surface temperature is reduced, which facilitates the inflow of intake air. Also, at the maximum temperature in the combustion chamber, the amount of heat absorbed by the wall surface is reduced to reduce the temperature difference between the combustion gas temperature and the wall surface temperature, and the thermal energy that escapes to the outside through the cylinder head and cylinder block is minimized. You can With this configuration, the intake efficiency of the engine can be improved and the thermal energy in the combustion chamber can be maximally recovered. Moreover, since the heat insulating sheet contains potassium titanate as a main component, it can be formed into an excellent heat insulating structure,
Moreover, the air layer formed on the heat insulating sheet, the heat insulating sheet itself or the air layer formed on the contact portion between the heat insulating sheet and the metal sheet can obtain a further excellent heat insulating effect, and the heat energy can be converted into the combustion energy. Can be locked in a room. Therefore, the energy recovery device can effectively recover the thermal energy.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the structure of an adiabatic engine according to the present invention, and FIG. 2 is a sectional view showing the structure of a conventional adiabatic engine. 1 ... Cylinder head, 2 ... Metal material, 3 ... Cylinder head liner, 4 ... Insulation sheet, 5 ... Combustion chamber, 6
…… Insulation gasket, 7 …… Gasket, 8 …… Piston, 9 …… Intake / exhaust valve, 10 …… Insulation engine structure, 11 ……
… Intake and exhaust ports, 12 …… Cylinder, 13 …… Piston head, 14 …… Piston skirt.

Claims (6)

[Claims] 1. A structure of an adiabatic engine, characterized in that a heat insulating sheet is provided on the outer surface of a cylinder head liner made of ceramics, and a metal material is cast around the outer surface of the heat insulating sheet. 2. The structure of an adiabatic engine according to claim 1, wherein the cylinder head liner has a thin wall thickness to reduce the heat capacity. 3. The structure of the heat insulation engine according to claim 1, wherein an air layer is formed on the heat insulation sheet. 4. The structure of the heat insulating engine according to claim 1, wherein the heat insulating sheet is formed by laminating titanate paper. 5. The structure of the heat insulating engine according to claim 1, wherein the heat insulating sheet is formed by mixing potassium titanate whiskers with an organic binder and integrally molding them. 6. The structure of the heat insulating engine according to claim 1, wherein the heat insulating sheet is formed by mixing potassium titanate whiskers, alumina fibers and an organic binder and molding the mixture.