JPH07109176B2 - 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, engine members such as adiabatic engines using a ceramic material as a heat insulating material or a heat resistant material are disclosed in
-192647 and Japanese Patent Laid-Open No. 60-90955.

First, the cylinder liner of the heat insulation engine disclosed in Japanese Utility Model Laid-Open No. Sho 59-192647 will be outlined with reference to FIG.

The cylinder liner of the adiabatic engine has a cylinder head inner wall portion 26 and a cylinder liner upper portion 28 formed integrally with each other.
Although it is configured to be larger than the inner diameter of 27, it is installed on the cylinder head through a heat insulating gasket on the outer surface of the liner upper portion 28, which is not shown in the figure, and therefore, is not attached to the cylinder liner upper portion 28 of the liner head 25. Piston head 29
It is possible to operate smoothly and with good durability without contact with.

Next, the structure of the adiabatic engine disclosed in JP-A-60-90955 will be outlined with reference to FIG. In FIG. 4, the structure of the adiabatic engine is indicated generally by the numeral 30.

The structure 30 of the adiabatic engine has a heat-reflecting surface formed on the inner peripheral wall 33 of a cylindrical recess 32 provided in the lower half of the cylinder head 31, and an inverted cup-shaped headliner made of ceramics in the cylindrical recess 32 of the cylinder head 31. 34 is fitted with an empty portion 35 provided around this. A heat insulating material 36 such as ceramic fiber or 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 head liner 34 is connected to the inner end wall 33 of the cylindrical recess 32 of the cylinder head 31 via the gasket 43, and the lower end wall of the head liner 34 is inserted to the cylinder block 37 and the cylinder liner via the elastic gasket 44. The upper ends of 39 are pressed respectively to alleviate stress concentration in the headliner 34 due to imbalance of tightening force and thermal deformation, and
Since the void 35 is formed, the headliner 34 surrounding the combustion chamber 40
The heat conduction from the cylinder head to the cylinder head 31 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, by accommodating the heat insulating material 36 such as ceramic fiber in the void 35, it is possible to prevent convection of air in the void 35 and suppress heat transfer from the wall portion of the headliner 34 to the cylinder head 31.

Therefore, since the heat of the combustion chamber 40 is suppressed from being dissipated to the outside from the headliner 34, the exhaust gas can be sent to the exhaust turbocharger or the like through the exhaust passage in a high temperature state, and the exhaust gas has The heat energy can be used to the maximum extent. 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 portion facing the combustion chamber of the engine is made of ceramics such as silicon nitride having excellent heat resistance, heat insulation, and heat shock resistance, and can withstand high temperature combustion gas, but if the wall thickness is too large, There is a problem in that the heat capacity becomes large and thus the inhalation efficiency decreases.

The liner head 25 including the cylinder head inner wall portion 26 and the cylinder liner upper portion 28 in the cylinder liner of the heat insulating engine disclosed in the above-mentioned Japanese Utility Model Publication No. Sho 59-192647, and the above-mentioned Japanese Patent Laid-Open Publication No. 60-90955. A headliner composed of an upper end wall 41 and a lower end wall in the structure of an adiabatic engine
34 is made of a relatively thick ceramic material, and has a large heat capacity in the same manner as described above, and does not reduce the heat capacity of a portion exposed to a high temperature.

The upper end wall 41 of the headliner 34 is connected to the inner end wall 33 of the cylindrical recess 32 of the cylinder head 31 via the gasket 43, and the lower end wall of the headliner 34 is connected to the cylinder block 37 and the cylinder liner via the elastic gasket 44. Since they are installed by being pressed against the upper end of 39 respectively, and a void 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. Can not.

The purpose of this invention is to solve the above problems,
A structure in which the thickness of the ceramic member facing the combustion chamber side of the cylinder head liner, in which the lower surface of the cylinder head and the upper portion of the cylinder liner are integrated, can be made as thin as possible,
The heat capacity of the cylinder head liner facing the combustion chamber side, which is high in temperature, is configured to be small, thereby improving the intake efficiency of the engine and improving the strength deterioration due to the decrease in the thickness of the ceramic material and improving the sealing performance. And to provide a structure of an adiabatic engine configured to improve the adiabatic function.

[Means for solving problems]

The present invention is configured as follows to achieve the above object. That is, according to the present invention, in the structure of an adiabatic engine in which the cylinder head liner is fitted in the cylindrical recess formed in the cylinder head, the cylinder head liner has a cylinder head lower surface portion and a cylinder liner upper portion that are integrally structured. A cylinder head liner body, and a thin ceramic member disposed in the cylinder head liner body via a heat insulating material and forming a combustion chamber, between the upper end surface of the ceramic member and the lower surface of the cylinder head. A heat insulating sheet is interposed between the cylinder head liner main body and the ceramic member, and the ends of the cylinder head liner body and the ceramic member are fixed to each other by a coupling member.

Further, in the structure of this adiabatic engine, the cylinder head liner body is made of a material having a thermal expansion coefficient substantially equal to that of a ceramic material. The upper portion of the cylinder liner is made of a ceramic material. Further, a ceramic coating layer is formed on the valve intake and exhaust holes of the cylinder head liner body.

[Action]

The structure of the adiabatic engine according to the present invention is configured as described above and operates as follows. That is, in the structure of this adiabatic engine, the cylinder head liner is formed in a cylindrical recess formed in the cylinder head, and the cylinder head lower surface portion and the cylinder liner upper portion are integrally formed, and the cylinder head liner body. A thin ceramic member that is disposed inside via a heat insulating material to form a combustion chamber, and a heat insulating sheet is interposed between the upper end surface of the ceramic member and the lower surface of the cylinder head, and the thin lid head Since the end portions of the liner body and the ceramic member are fixed by a connecting member such as a metal packing, the thickness of the ceramic member forming the combustion chamber exposed to the high temperature combustion gas can be made as thin as possible. The heat capacity can be reduced, and the positioning and sealing properties of both can be improved.

Further, since the ceramic coating layer is formed in the valve intake / exhaust holes of the main body of the thin lid head liner, it is possible to improve the heat insulating function also in the valve intake / exhaust holes made of a metal material.

That is, in order to improve the intake efficiency of the engine, it is important to minimize the heat capacity of the ceramics inner wall that becomes hot in order to minimize the heat received from the inner wall of the cylinder of the adiabatic engine. By making it small, the wall surface immediately cools at the time of intake of the engine, and the temperature difference between the intake air temperature and the wall surface temperature becomes small, thereby facilitating 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, cylinder block, etc. is minimized. be able to.

〔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.

The structure 10 of this heat insulating engine discloses only the technical concept of the heat insulating structure of the cylinder head and the cylinder liner, and the heat insulating structure of the cylinder, piston and intake / exhaust valves 9, 9 ′ other than the above. Although not disclosed and shown, these cylinders, pistons, and intake / exhaust valves 9, 9'for the adiabatic engine,
It is needless to say that the object of heat insulation can be more surely achieved by forming the heat insulation structure with a ceramic material such as silicon nitride, a heat insulation sealant or the like.

The structure of the adiabatic engine according to the present invention has a cylinder head liner fitted in a cylindrical recess (corresponding to reference numeral 32 in FIG. 4) formed in the cylinder head (corresponding to reference numeral 31 in FIG. 4) shown in FIG. (Corresponding to reference numeral 34 in FIG. 4), the cylinder head liner includes a cylinder head liner body 1 in which a cylinder head lower surface portion 2 and a cylinder liner upper portion 3 are integrally structured, and the cylinder head liner body 1 And a thin ceramic member 4 which is disposed inside via a heat insulating material and forms a combustion chamber 5.

The cylinder head liner body 1 is made of a material having a thermal expansion coefficient approximately equal to that of a ceramic material, for example, a heat-resistant alloy such as nickel-chromium alloy. The ceramic member 4 is made thin from a ceramic material such as silicon nitride or silicon carbide, and has a small heat capacity. The liner portion of the ceramic member 4 is formed in a structure having a step portion 14.

Further, the heat insulating material interposed between the thin ceramic member 4 and the cylinder head liner body 1 is made of a molded product such as ceramic fiber, and is provided at a portion 15 below the step portion 14 of the ceramic member 4. Has a heat insulating pipe 8 as a heat insulating material, a heat insulating fiber 13 as a heat insulating material at a portion 16 above the stepped portion 14, and a heat insulating sheet 6 as a heat insulating material at the upper surface of the ceramic member 4. . Moreover, the ceramic member 4 and the cylinder liner upper portion 3
The joints at the ends of and are fixed to each other by a coupling member 7 such as a composite metal packing of copper or stainless steel and a heat insulating material in order to improve the gas sealability.

Therefore, the ceramic member 4 forming the combustion chamber 5 and the metal cylinder head liner body 1 are positioned at the liner end portion, that is, the lower end portion, and the cylinder head lower surface portion 2 except for the valve seats 17 and 17 ′ is located between them. Since the heat insulating material is interposed therebetween, the ceramic member 4 is installed in a substantially floating state.

By the way, the valve seats 17 and 17 'for the intake / exhaust valves are composed of a metal portion of the cylinder head lower surface portion 2 of the cylinder head liner body 1, and no heat insulating material or ceramic member is provided in this portion. Further, the valve intake / exhaust holes 11 and 11 'formed in the lower surface 2 of the cylinder head are provided with a ceramic coating layer such as a zirconia coating layer.
Forming twelve.

The heat insulating fiber 13, which is a heat insulating material, is made of a ceramic fiber made of a mixture with potassium titanate whiskers, alumina fibers, or the like, and in some cases, a heat insulating air layer can be formed in the ceramic fiber.

As for the heat insulating sheet 6 and the heat insulating pipe 8 which are heat insulating materials, for example, one in which potassium titanate paper is laminated, one in which an organic binder is mixed with potassium titanate whiskers, and which is integrally formed, or potassium titanate whiskers, alumina. For example, it may be formed by mixing fibers and an organic binder.

In addition, as examples of these heat insulating materials, a ceramic sheet impregnated with potassium titanate is laminated, that is, laminated, or an organic binder containing potassium titanate whiskers as a main component is mixed to form a paper form. The sheet laminated as described above, a sheet formed by mixing an organic binder containing potassium titanate whiskers as a main component with an organic binder and reinforced by sandwiching the upper and lower surfaces with alumina fiber sheets, and potassium titanate whiskers. Alumina fibers which are alumina short fibers containing as a main component and an organic binder are mixed and molded into a cup shape, or not limited to potassium titanate whiskers, but ceramic fibers such as zirconia fibers may be used. Of course.

By constructing the structure of the heat insulation engine according to the present invention as described above, the ceramic member 4 arranged on the inner surface of the cylinder head liner body 1 is provided with the combustion chamber 5 of the engine.
Although it is exposed to the high temperature combustion gas inside, the thickness of the ceramic member 4 can be made as thin as possible in order to minimize the heat received from the inner wall of the combustion chamber 5, and the heat capacity should be reduced. You can

Further, in order to prevent the strength from being deteriorated by making the ceramic member 4 thin, the strength is reinforced by the metal cylinder head liner main body 1 via the heat insulating material on the outer surface of the ceramic member 4, and the heat insulating material is used. The heat insulating property is improved by this, and the positioning and sealing property are improved by connecting both ends.

Next, another embodiment of the structure of the adiabatic engine according to the present invention will be described with reference to FIG. The structure 20 of this adiabatic engine is the same structure as the structure 10 of the adiabatic engine except that the structure of the cylinder head liner body is different, and therefore, the same parts are designated by the same reference numerals. The description of their configurations and functions is omitted.

In the structure 10 of the adiabatic engine, the cylinder head liner body 1 including the cylinder head lower surface portion 2 and the cylinder liner upper portion 3 is made of a metal material having a thermal expansion coefficient substantially equal to that of the ceramic material. On the other hand, in the structure 20 of this adiabatic engine, the cylinder head liner body 21 is composed of the cylinder head lower surface portion 22 and the cylinder liner upper portion 23. The lower surface portion 22 of the cylinder head is made of a metal material having a thermal expansion coefficient approximately equal to that of the ceramic material, and
The cylinder liner upper portion 23 is made of a ceramic material such as silicon nitride or silicon carbide. In this case, to install the ceramic member 4 on the inner peripheral surface of the cylinder liner upper portion 23,
A powder of aluminum titanate and alumina may be enclosed as a heat insulating material 24 between the upper portion 23 of the cylinder liner and the ceramic member 4 and sintered at a low temperature to be fixed.

〔The invention's effect〕

The structure of the heat insulation engine according to the present invention is configured as described above and has the following effects. That is, the structure of this adiabatic engine is a cylinder head liner body in which the cylinder head liner in the cylindrical recess of the cylinder head has a cylinder head lower surface portion and a cylinder liner upper portion integrally formed, and a heat insulating material in the cylinder head liner body. A thin ceramic member that forms a combustion chamber with a heat insulating sheet interposed between the upper end surface of the ceramic member and the lower surface of the cylinder head, and the cylinder head liner body and the ceramic member. Since the ends of and are fixed by the connecting member, the thickness of the ceramic member forming the combustion chamber exposed to the high temperature combustion gas can be formed as thin as possible,
The heat capacity can be reduced and therefore the intake efficiency of the engine can be improved.

Moreover, since the ends of the both are fixed by a coupling member such as a metal packing, the ceramic member can be positioned extremely firmly and accurately with respect to the cylinder head liner body, and the hermeticity can be improved. Can solve problems. Further, since a ceramic coating layer such as a zirconia coating layer is formed in the valve intake / exhaust holes on the upper surface of the thin lida head, it is possible to improve the heat insulating function also in the valve intake / exhaust holes made of a metallic material.

In this way, 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 as much as possible, so that the thermal energy can be maximally recovered. .

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 stroke and exhaust stroke 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.

Also, in the intake stroke of the engine, the portion that comes into contact with the high temperature gas, that is, the cylinder head liner, has a small heat capacity, so that 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 of the thin ceramic member forming the combustion chamber, 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 fuel 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 material is mainly composed of a ceramic material such as potassium titanate, it can be formed into an excellent heat insulating structure, and the air layer formed in the heat insulating material can further improve the heat insulating effect. A limited amount of heat energy can be sent from the combustion chamber through the exhaust port to the energy recovery device installed downstream, and therefore, the energy recovery device can effectively recover the heat energy.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the structure of the heat insulation engine according to the present invention, FIG. 2 is a sectional view showing another embodiment of the structure of the heat insulation engine according to the present invention, and FIG. 3 is a view of the conventional heat insulation engine. FIG. 4 is a sectional view showing an example of a cylinder liner, and FIG. 4 is a sectional view showing an example of the structure of a conventional adiabatic engine. 1 ... Cylinder head liner body, 2 ... Cylinder head lower surface part, 3 ... Cylinder liner upper part, 4 ... Ceramic member, 5 ... Combustion chamber, 6 ... Insulating sheet, 7 ... Coupling member, 8 ... Insulation pipe, 9, 9 '... intake and exhaust valves, 10,
20 …… Insulation engine structure, 12 …… Ceramic coating layer, 13 …… Insulation fiber, 17,17 ′ …… Valve seat, 22 …… Cylinder head bottom surface, 23 …… Cylinder liner upper part, 24 …… Insulation material .

Claims (4)

[Claims] 1. In a structure of an adiabatic engine in which a cylinder head liner is fitted in a cylindrical recess formed in a cylinder head, the cylinder head liner has a cylinder head lower surface portion and a cylinder liner upper portion integrally formed. A cylinder head liner main body and a thin ceramic member disposed inside the cylinder head liner main body via a heat insulating material to form a combustion chamber are provided, and between the upper end surface of the ceramic member and the cylinder head lower surface portion. A heat insulating engine structure, wherein a heat insulating sheet is interposed, and ends of the cylinder head liner body and the ceramic member are fixed to each other by a connecting member. 2. The structure of the heat insulation engine according to claim 1, wherein the cylinder head liner body is made of a material having a thermal expansion coefficient substantially equal to that of a ceramic material. 3. The cylinder liner upper portion is made of a ceramic material.
The structure of the heat insulation engine according to the item. 4. The structure of the adiabatic engine according to claim 1, wherein a ceramic coating layer is formed in the valve intake and exhaust holes of the cylinder head liner body.