JP2785351B2 - Insulated engine with auxiliary combustion chamber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an insulated engine with a sub-combustion chamber.

[Conventional technology]

Conventionally, a heat insulating engine using a ceramic material as a heat insulating material or a heat resistant material is disclosed in, for example, Japanese Patent Application Laid-Open No. 59-46317. With respect to the combustion chamber components of the internal combustion engine disclosed in the publication, the combustion chamber components constituting the combustion chamber walls such as the sub-chamber constituent members, the cylinder head, the cylinder liner, the piston, and the intake / exhaust valves are replaced with ceramics having excellent heat insulating properties. It is constituted by The combustion chamber components are based on silicon-based non-oxide ceramics such as silicon nitride ceramics and silicon carbide ceramics. It is provided with a thin layer of, to improve the combustion by the catalytic action of the noble metal catalyst,
The aim is to reduce both unburned hydrocarbons in the exhaust gas and to combat white smoke in diesel engines.

An insulated engine in which a ceramic liner head having a cylinder liner is fitted inside a cylinder head is disclosed in, for example, Japanese Patent Application Laid-Open No. 59-122765.

Generally, there are two types of engine operating principles, that is, a four-stroke engine and a two-stroke engine. In a two-stroke engine, an intake process and an exhaust process are performed in a part of a combustion process and a compression process, and a piston is used. One cycle is completed in two strokes, that is, one rotation of the crankshaft. The two-stroke engine includes a head valve type and a uniflow type having an exhaust valve in a cylinder head. Some of the two-cycle engines are provided with a plurality of valves because the opening period of the valves is shorter than that of the four-cycle type.

[Problems to be solved by the invention]

Incidentally, the temperature of the intake port may be lower in order to improve the intake efficiency, and the temperature of the exhaust port may be higher. However, in an insulated engine such as a cylinder head using the above ceramics as a heat insulating material or a heat resistant material, if a sub-combustion chamber and an intake port for arranging an intake valve are formed in the cylinder head, the fire deck portion has heat resistance. In short, it is necessary to keep the temperature as low as possible due to the presence of the intake port, and there is a problem that the temperature distribution of the fire deck of the cylinder head becomes non-uniform and the strength of the fire deck part is deteriorated by thermal influence. Furthermore, it is extremely difficult to obtain sufficient heat insulating properties, and there are problems such as an increase in wall thickness in order to obtain sufficient heat insulating properties. That is, the part facing the combustion chamber of the engine, that is, the fire deck, is heat-resistant, heat-insulating,
Composed of ceramics such as silicon nitride with excellent heat shock properties, it can withstand high-temperature combustion gas, but it needs to be kept at a relatively low temperature near the intake port and at the boundary where the sub-combustion chamber is formed However, there is a problem that the thermal stress increases due to the non-uniformity of the mounting property, the sealing property, and the temperature distribution, thereby causing cracks and the like.

In addition, in the case of the above-described insulated engine, the combustion chamber including the cylinder formed in the cylinder head and the cylinder block has a heat-insulating structure made of a heat-insulating material, a ceramic material, etc., and the welding efficiency is reduced due to the high heat in the cylinder. And lowers the output. The reason is that the intake valve and the exhaust valve are arranged on the cylinder head and are arranged close to each other. In addition, in an insulated engine, the cylinder head and the upper part of the cylinder are insulated, so the upper part of the combustion chamber and the wall surface are hot. The temperature of the exhaust gas and the upper part of the combustion chamber is considerably higher. Therefore, the intake port and the intake air are easily thermally affected by the exhaust port, the upper wall of the combustion chamber, and the exhaust gas, and the fresh air sucked into the cylinder receives heat from the cylinder or the wall surface and expands by heating. Is expanded due to thermal influence, and the amount of intake air is extremely reduced, for example, to 20% or more, and the intake efficiency is reduced.

However, in an engine with an intake port provided below the cylinder liner, air exchange involves a phenomenon in which when an exhaust valve opens and exhaust is performed through the exhaust port, a pressure wave or pulse wave is generated in the cylinder and the exhaust gas is pushed out. Become. As a result, fresh air flows into the negative pressure zone generated downstream of the exhaust gas from the lower part of the cylinder, but since the lower part of the cylinder is not so hot compared to the cylinder head, the fresh air is Insensitive to wall temperature. This has the advantage that the scavenging air amount or the intake air amount does not decrease particularly when the fresh air is sucked in from the lower part of the cylinder in the adiabatic engine.

An object of the present invention is to solve the above-described problem. In an insulated engine in which a combustion chamber including a cylinder head and a cylinder is configured to have an insulated structure, the temperature of a cylinder head portion becomes high, but a lower portion of the cylinder farther from the cylinder head has a lower portion. Focusing on the fact that the temperature is not relatively high, the intake port is eliminated from the cylinder head, and the intake port is provided below the cylinder liner separated from the exhaust port to perform two-cycle or four-cycle operation to improve intake efficiency. Since the intake port is not provided in the cylinder head, the cooling system from the cylinder head is eliminated to maintain a high temperature state, and the wall of the sub combustion chamber, the fire deck of the cylinder head, that is, the lower surface of the cylinder head and the upper portion of the cylinder liner are made of ceramic material. To secure heat resistance and reduce the number of parts. To improve the mounting and sealability, particularly, to provide a secondary combustion chamber with a heat insulating engine which can prevent the occurrence of cracks due to thermal stress by eliminating the non-uniformity of the temperature distribution.

[Means for solving the problem]

The present invention is configured as follows to achieve the above object. That is, according to the present invention, a lower surface portion of a cylinder head serving as a fire deck of a cylinder head, an inner wall of a sub-combustion chamber provided on the cylinder head, and an upper portion of a cylinder liner are integrally formed of a ceramic material, and an outer surface of the integrated structure is formed. Is covered with a heat insulating gasket to form a heat insulating structure,
The present invention relates to an adiabatic engine with a sub-combustion chamber in which an exhaust valve is disposed in an exhaust port formed in the cylinder head and an intake port is formed below a cylinder liner.

[Action]

The adiabatic engine with a sub-combustion chamber according to the present invention is configured as described above, and operates as follows. That is, in the heat-insulated engine with the sub-combustion chamber, the lower surface portion of the cylinder head, the inner wall of the sub-combustion chamber, and the upper portion of the cylinder liner are formed of a ceramic material into an integrated structure, and the outer surface of the integrated structure is covered with an insulating gasket. Since the exhaust valve is arranged in the exhaust port formed in the cylinder head and the intake port is formed in the lower part of the cylinder liner, the air taken in from the intake port is heated to the high temperature of the exhaust port, the combustion chamber wall and the exhaust gas. It is possible to prevent the intake air flow from decreasing due to the thermal expansion of the intake air without being affected by the heat of the region. The combustion chamber wall and the upper part of the cylinder liner are made of ceramic material so that they have an integral structure. There is no boundary between the sub-combustion chamber and the like, and there is no problem in sealing.The mounting property of the sub-combustion chamber and the sealing property of the exhaust valve seat can be improved, and the temperature distribution can be uniform and the thermal stress can be reduced. The occurrence of cracks and the like can be prevented.

〔Example〕

Hereinafter, an embodiment of an insulated engine with a sub-combustion chamber according to the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of an adiabatic engine with a sub-combustion chamber according to the present invention. The adiabatic engine with the sub-combustion chamber can be operated in two cycles, and in some cases, in four cycles, and is configured as a uniflow type in which the exhaust valve 1 is disposed in the cylinder head 3 to perform a scavenging action or an exhaust action. This is performed by an airflow in a certain direction with respect to the cylinder center line to increase the efficiency of the engine. A valve seat 17 is disposed at the inlet of the exhaust port 2, and the exhaust valve 1 has a valve face of the valve seat 17. It is arranged so as to be able to open and close so that it can be separated from and connected to. Further, a sub-combustion chamber 20 provided with a fuel injection nozzle 18 is formed in the cylinder head 3. A cylinder liner 9 is fitted into a cylinder formed in the cylinder block 4, and a number of intake ports 12 are formed in a lower part of the cylinder liner 9 in a circumferential direction. The formed annular intake port 11 communicates. Further, the intake port 11 is connected to a supercharger 21 such as a turbocharger or a compressor. Therefore, if the boost pressure is improved by the supercharger 21, the torque at the time of low speed of the engine can be increased. In the case of 4-cycle operation, the turbocharger
By the control of 21, the exhaust gas can be prevented from flowing back to the intake port in the explosion step and the exhaust step, and a four-cycle operation can be established.

Regarding the structure of the upper part of the combustion chamber 8 in the adiabatic engine with a sub-combustion chamber, in particular, the cylinder head lower surface part 6 of the cylinder head 3, the cylinder liner upper part 7 constituting the cylinder, and the sub-combustion chamber 20 provided in the cylinder head 3 The sub-combustion chamber wall 14 to be formed is made of a ceramic material such as silicon nitride (Si ₃ N ₄ ) or silicon carbide (SiC) and has a structure with high heat resistance as an integrated structure 5. Further, the integral structure 5 composed of the cylinder head lower surface portion 6, the cylinder liner upper portion 7, and the sub-combustion chamber inner wall portion 14 is made of a heat insulating material made of a low heat conductive material such as aluminum titanate and potassium titanate. It is covered with a heat insulating gasket 10 made of and has a heat insulating structure. Further, a fuel injection nozzle 18 is disposed above the inner wall 14 forming the sub-combustion chamber 20, and an access passage 19 is formed in the sub-combustion chamber wall 14. Further, the inflow / outflow passage 19 is set in an inclined state so that swirl is promoted in the sub-combustion chamber 20 by the inflow and outflow of the fluid, and further, in order to promote mixing of fuel spray and air in the sub-combustion chamber 20, The axis of the inlet / outlet passage 19 and the axis of the fuel injection nozzle 18 are deviated, and are arranged to face each other.

Further, at the boundary between the lower end surface of the cylinder liner upper part 7 of the head liner 5 and the upper end surface of the lower part of the cylinder liner 9,
In order to prevent the generation of heat flow from the upper part 7 of the liner to the lower part of the liner 9, an insulating gasket 15 made of an insulating material is interposed. The cylinder liner 9 can be made of a metal material or a ceramic material. By disposing the heat insulating gasket 15 at the boundary between the upper portion 7 of the cylinder liner and the lower portion of the cylinder liner 9, the temperature distribution at the boundary constituting the combustion chamber 8 is as shown in FIG. For example, assuming that the temperature of the cylinder head lower surface portion 6 constituting the fire deck of the cylinder head 3 is 600 ° C., the temperature of the boundary where the heat insulating gasket 15 is arranged is 300 ° C., and the cylinder liner in which the intake port 12 is formed. 9 Lower temperature is 20
0 ° C or less. Therefore, the combustion state can be improved by maintaining the upper part of the combustion chamber at a high temperature, and the suction efficiency can be improved by maintaining the lower part of the combustion chamber at a low temperature.

Although not shown, the piston 13 reciprocating in the cylinder has a heat insulating structure made of a heat insulating layer, a ceramic material, and the like disposed in the piston head. In the figure, reference numeral 16 denotes a piston ring.

Further, in the adiabatic engine with the sub-combustion chamber, the exhaust valve 1 can be opened and closed by an electromagnetic force. The opening and closing operation of the exhaust valve 1 is independent of the rotation of the crank, and the stroke position of the piston, that is, the crank angle. The opening and closing timing of the exhaust valve 1 can be controlled to be in an optimal state in response to a detection signal from a position sensor for detecting the pressure. That is, the electromagnetic valve driving device of the exhaust valve 1 opens and closes the valve by an electromagnetic force, and includes a rotation sensor for detecting the number of revolutions of the engine, a load sensor for detecting the load of the engine, and a stroke position of the piston 13, that is, a crank position. Receives each detection signal from the position sensor that detects the angle, and the intake flow rate sensor that detects the amount of intake air,
It can be controlled by a controller that issues a command in response to each of these detection signals.

〔The invention's effect〕

The adiabatic engine with a sub-combustion chamber according to the present invention is configured as described above, and has the following effects.

That is, in the adiabatic engine with the sub-combustion chamber, the lower surface portion of the cylinder head serving as the fire deck of the cylinder head, the inner wall of the sub-combustion chamber provided on the cylinder head, and the upper portion of the cylinder liner are formed into an integral structure with a ceramic material. The outer surface of the integrated structure is covered with a heat-insulating gasket to form a heat-insulating structure, an exhaust valve is arranged at an exhaust port formed in the cylinder head, and an intake port is formed below the cylinder liner, so that air is sucked from the intake port. The air is not affected by the heat of the exhaust port, the combustion chamber wall and the high temperature region of the exhaust gas, and the intake air flow does not decrease due to the thermal expansion of the intake air, so that a high output of the engine can be obtained. In addition, since the portion that becomes high in temperature by combustion, that is, the lower surface portion of the cylinder head where the exhaust port is formed, the inner wall of the sub-combustion chamber, and the upper portion of the cylinder liner are integrally formed of a ceramic material, a structure that is rich in heat resistance with a ceramic material There is no mounting boundary such as a sub-combustion chamber, and there is no sealing problem, the mounting of the sub-combustion chamber and the sealing performance of the exhaust valve seat can be improved, and the temperature distribution becomes uniform and the thermal stress is reduced. It is possible to reduce the occurrence of cracks and the like. In addition, since there is no intake port in the head, the cooling system from the head can be eliminated, and the cooling system from the body can be eliminated, making the engine structure simpler. In the manufacture, a core or the like is not required, and the manufacturing cost can be reduced. In addition, the number of parts is reduced by the blocking, and the manufacturing cost can be further reduced.

Further, in this case, the exhaust gas is efficiently exhausted from the exhaust port provided in the cylinder head, and then the intake air is blown in a state in which the area of the negative pressure is filled in the wake of the pulse wave of the exhaust gas. The direction becomes a single direction, and therefore, even if the wall temperatures of the cylinder head and the upper portion of the cylinder are high, the suction efficiency in the suction process can be improved without the intake air being thermally affected.

Further, by providing the sub-combustion chamber, the temperature is increased in a short time to quickly execute the mixing of the fuel spray and the air, the combustion in the smoke generation temperature zone is immediately cleared, and the It is possible to provide an insulated engine capable of providing combustion in the NO _X generation temperature zone without blowing the introduced air as swirl into the main combustion chamber and reducing the intake efficiency of the introduced air.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining an embodiment of an insulated engine with a sub-combustion chamber according to the present invention, and FIG. 1 (A) is an explanatory diagram showing a temperature distribution of the insulated engine of FIG. 1 ... exhaust valve, 2 ... exhaust port, 3 ... cylinder head, 4 ... cylinder block, 5 ... integrated structure,
6 ... Cylinder head lower part, 7 ... Cylinder liner upper part, 8 ... Combustion chamber, 9 ... Cylinder liner, 10,15 ...
Insulated gasket, 11 ... intake port, 12 ... intake port, 13
… Piston, 14… wall of sub combustion chamber, 18… fuel injection nozzle, 20… sub combustion chamber, 21… supercharger.

Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI F02F 1/24 F02F 1/24 E (56) References JP-A-2-291421 (JP, A) JP-A-2-286857 (JP, A JP-A-59-122765 (JP, A) JP-A-63-255547 (JP, A) Japanese Translation of PCT International Publication No. Sho 62-501720 (JP, A) Japanese Utility Model Showa 60-141470 (JP, U) Japanese Utility Model Utility Model Sho 60- 82525 (JP, U) Patent 135889 (JP, C1) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02F 1/00 F02F 1/24 F02F 1/22 F02B 19/16 F02B 31/02

Claims (1)

(57) [Claims] A lower surface portion of a cylinder head serving as a fire deck of a cylinder head, an inner wall of a sub-combustion chamber provided on the cylinder head, and an upper portion of a cylinder liner are integrally formed of a ceramic material, and an outer surface of the integrated structure is formed of a ceramic material. An insulated engine with a sub-combustion chamber, wherein the engine is configured to be insulated by covering with an insulating gasket, an exhaust valve is arranged in an exhaust port formed in the cylinder head, and an intake port is formed below a cylinder liner.