JPH0689710B2 - Insulation 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 JP-A-60-90955 will be outlined with reference to FIG. In FIG. 6, 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, which has excellent heat resistance, heat insulation, and heat shock resistance, and can withstand high-temperature combustion gas, but if the wall thickness is too large, the heat capacity becomes large. However, there is a problem that the inhalation efficiency is lowered.

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 It has similar problems.

An object of the present invention is to eliminate the above-mentioned problems, to reduce the heat capacity of the cylinder head liner that faces the combustion chamber and has a high temperature by configuring the wall thickness of the cylinder head liner as thin as possible. It is to provide a structure of an adiabatic engine that can be constructed and thereby improve the intake efficiency of the engine.

The cylinder head liner here is a structure for cutting off heat only during a heat generation period during which combustion is active, and refers to a combination of the upper surface of the cylinder head and a part of the cylinder liner.

[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, the outer surface of the ceramic cylinder head liner,
Regarding the structure of a heat insulating engine covered with a heat insulating laminated gasket composed of a metal sheet and a sheet containing ceramic fiber as a main component, more specifically, in detail, the heat capacity of the cylinder head liner and the cylinder liner The cylinder head liner and the cylinder liner are made of silicon nitride ceramics, and an air layer is formed in the heat insulating laminated gasket. Is formed by laminating a ceramic fiber sheet such as potassium titanate whiskers and zirconia fibers and a metal sheet such as stainless steel, or the heat insulating laminated gasket is formed on top and bottom surfaces of ceramic fiber paper such as potassium titanate whiskers and zirconia fibers. The alumina A sheet reinforced by a fiber and a metal sheet such as stainless steel are laminated, or the heat insulating laminated gasket is a sheet obtained by mixing ceramic fibers such as potassium titanate whiskers or zirconia fibers with alumina fibers and stainless steel. The present invention relates to a structure of an adiabatic engine, which is configured by laminating the above-mentioned metal sheet.

[Action]

The structure of the heat insulation engine according to the present invention is configured as described above, and operates as follows. That is, according to the present invention, since the outer surface of the cylinder head liner made of ceramic is covered with the heat insulating laminated gasket composed of the metal sheet and the sheet containing the ceramic fiber as a main component,
The wall thickness of the cylinder head liner exposed to the high temperature combustion gas can be formed as thin as possible, and the heat capacity can be reduced, thus improving the intake efficiency of the engine. That is, in order to minimize the heat received from the inner wall of the cylinder of the adiabatic engine, it is important to minimize the heat capacity of the inner wall of the ceramics that becomes high temperature. The wall surface cools immediately, reducing the temperature difference between the intake air temperature and the wall surface temperature, thereby facilitating the inflow of intake air. Further, when the maximum temperature in the combustion chamber is reached, 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.
Minimize the thermal energy that escapes to the outside through the cylinder block, etc. By configuring in this way,
While improving the intake efficiency of the engine, the thermal energy in the combustion chamber is sent to the energy recovery device installed downstream through the exhaust port to the maximum extent. Moreover, as the organic binder is mixed into the ceramic fiber such as potassium titanate sheet or zirconia fiber to prevent the falling property, the thermal conductivity deteriorates, so that the compounding with the metal sheet prevents the falling property and the rigidity from decreasing. To do. That is, the rigidity is increased by the metal sheet, and the structure is made to have excellent pressure resistance. Further, since the heat insulating laminated gasket mainly composed of ceramic fibers such as potassium titanate and zirconia fiber is used, an excellent heat insulating structure is obtained. In addition, the air layer formed on the heat-insulating laminated gasket can provide a further excellent heat-insulating effect.

〔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 liner, the piston, and the intake / exhaust valve also have silicon nitride ceramics, a heat insulating sealing material, or the like. Needless to say, this can be achieved more reliably by using a heat insulating structure. In this heat insulating engine structure 10, a cylinder head liner 1 facing a combustion chamber 5 of the engine includes a head liner portion 2 and a cylinder liner portion 3. The cylinder head liner 1 is made of silicon nitride ceramics. The cylinder head liner 1 is connected to a cylinder 12 via a gasket 7. 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 liner 1, and this intake / exhaust port 11 is connected to the intake / exhaust valve 9
It is configured to be opened and closed by. The cylinder head liner 1 is formed so that the wall thickness of the cylinder head liner 1 is as thin as possible, and the outer surface of the cylinder head liner 1 is made of a laminated gasket having excellent heat insulation and pressure resistance, that is, heat insulation laminated gaskets 4 and 6. To cover. Specifically, the headliner portion 2 of the cylinder headliner 1 is covered with a heat insulating laminated gasket 6, and the cylinder liner portion 3 is covered with a heat insulating laminated gasket 4.

Next, referring to FIG. 2, FIG. 3, FIG. 4 and FIG.
An example of the heat insulating laminated gasket will be described in detail. FIG. 2 shows an example of the heat insulating laminated gaskets 4 and 6 applied to the structure 10 of the heat insulating engine according to the present invention. The heat-insulating laminated gaskets 4 and 6 are configured by alternately laminating or stacking heat-insulating sheets 19 and metal sheets 15 such as stainless steel, and an air layer 18 is provided at a contact portion between the heat-insulating sheets 19 and the metal sheet 15. Has been formed. It is preferable that the metal of the metal sheet 15 has a coefficient of thermal expansion substantially the same as that of silicon nitride, which is a material of the cylinder head liner 1. The heat insulating sheet 19 is composed of, for example, a mixture of about 80% potassium titanate whiskers 16 as a main component and about 20% alumina fibers 17 as a subcomponent, and the fibers of these whiskers and fibers. Are not consecutive,
An air layer 18 is formed inside so that a further excellent heat insulating effect can be obtained. 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 0.00012ca
l / cm sec ℃).

In FIG. 3, an example of the heat insulating laminated gaskets 4 and 6 is partially shown. The heat insulating laminated gaskets 4 and 6 are obtained by laminating a metal sheet 15 on a heat insulating sheet 20 which is composed of potassium titanate whiskers 16 as a main component and mixed with an organic binder to have a paper shape.

In FIG. 4, another example of the heat insulating laminated gaskets 4 and 6 is partially shown. This heat insulation laminated gasket 4,6
A sheet formed by mixing an organic binder containing potassium titanate whiskers 16 as a main component to form a paper is reinforced by sandwiching the upper and lower surfaces with an alumina fiber sheet 22 to form a heat insulating sheet 21, and the heat insulating sheet 21 and a metal sheet 15 And is laminated.

In FIG. 5, yet another example of the heat insulating laminated gaskets 4 and 6 is partially shown. This insulation laminated gasket 4,6
Has a structure similar to that of the heat insulating sheet 19 shown in FIG. 2, in which the alumina fiber 17 which is an alumina short fiber is mixed with the potassium titanate whiskers 16 as a main component,
It is composed of a heat insulating sheet 19 configured in a paper shape, and the heat insulating sheet 19 and the metal sheet 15 are laminated to improve the strength.

Although an example using potassium titanate whiskers is shown for each of the above heat insulating laminated gaskets 4 and 6, ceramic fibers such as zirconia fibers may be used as a main component, and the invention is not limited to potassium titanate whiskers. .

〔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, according to the present invention, since the outer surface of the ceramic cylinder head liner is covered with the heat insulating laminated gasket including the metal sheet and the sheet containing ceramic fiber as a main component, the cylinder head liner exposed to high temperature combustion gas is used. Can be made as thin as possible and the heat capacity can be reduced, thus improving the intake efficiency of the engine. That is, the heat capacity of the cylinder head liner, which is brought into contact with the high temperature gas in the engine combustion chamber and becomes high in temperature, can be configured to be as small as possible, and the intake efficiency of the engine can be improved. 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 through the exhaust port without the thermal energy remaining in the combustion chamber. Further, in the intake process of the engine, since the portion contacting the high temperature gas, that is, the cylinder head liner has a small heat capacity, it is immediately cooled to an appropriate temperature, and intake air is prevented from flowing into the combustion chamber. And there is no phenomenon that the inhalation efficiency is lowered. 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 time of the maximum temperature in the cylinder, the amount of heat absorbed by the wall surface can be 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 can be minimized. it can. With this configuration, it is possible to improve the intake efficiency of the engine and to maximize the thermal energy in the combustion chamber through the intake port to the energy recovery device provided downstream to maximize the thermal energy recovery. it can. Moreover, the metal sheet can increase the rigidity of the heat insulating laminated gasket and improve the pressure resistance, and further, the heat insulating laminated gasket mainly comprises ceramic fibers such as potassium titanate whiskers and zirconia fibers, so that it has an excellent heat insulating structure. The air layer formed on the heat insulating laminated gasket, the heat insulating sheet itself or the air layer formed on the contact portion between the heat insulating sheet and the metal sheet can achieve a further excellent heat insulating effect,
Thermal energy can be trapped in the combustion chamber.
Therefore, the energy recovery device can effectively recover the thermal energy.

[Brief description of drawings]

1 is a sectional view showing an embodiment of the structure of the heat insulating engine according to the present invention, FIG. 2 is a cross sectional view showing an example of the heat insulating laminated gasket of FIG. 1, and FIG. 3 is a heat insulating laminated gasket of FIG. FIG. 4 is a sectional view partially showing an example of the heat insulating sheet, FIG. 4 is a sectional view partially showing another example of the heat insulating sheet in the heat insulating laminated gasket in FIG. 1, and FIG. 5 is in the heat insulating laminated gasket in FIG. Sectional drawing which partially shows another example of a heat insulation sheet, and FIG. 6 is sectional drawing which shows the structure of the conventional heat insulation engine. 1 ... Cylinder headliner, 2 ... Headliner part,
3 ... Cylinder liner part, 4, 6 ... Insulating laminated gasket, 5 ... Combustion chamber, 7 ... Gasket, 8 ... Piston, 9 ... Intake / exhaust valve, 10 ... Insulation engine structure, 11 ...
… Intake and exhaust ports, 12 …… Cylinder, 15 …… Metal sheet, 16 …… Potassium titanate whiskers, 17 …… Alumina fiber, 18 …… Air layer, 19,20,21 …… Insulation sheet,
22 …… Alumina fiber sheet.

Claims (7)

[Claims] 1. A structure of an adiabatic engine characterized in that an outer surface of a ceramic cylinder head liner is covered with an adiabatic laminated gasket composed of a metal sheet and a sheet containing ceramic fibers as a main component. 2. The structure of an adiabatic engine according to claim 1, wherein the cylinder head liner is configured to be as thin as possible in order to reduce the heat capacity. 3. The structure of an adiabatic engine according to claim 1, wherein the cylinder head liner is made of silicon nitride ceramics. 4. The structure of the heat insulation engine according to claim 1, wherein an air layer is formed on the heat insulation laminated gasket. 5. The heat insulating laminated gasket is formed by laminating a ceramic fiber sheet and a metal sheet such as stainless steel.
The structure of the heat insulation engine according to the item. 6. The heat insulating laminated gasket is formed by laminating a sheet in which upper and lower surfaces of ceramic fiber paper are reinforced by alumina fibers and a sheet made of metal such as stainless steel are laminated. Structure of the heat insulation engine described in. 7. The heat insulating laminated gasket is formed by laminating a sheet made of a mixture of ceramic fibers and alumina fibers and a metal sheet made of stainless steel or the like. Structure of adiabatic engine.