JP3070186B2 - Insulated engine with sub-chamber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat insulating engine having a sub-chamber in which a cylinder head has a heat insulating structure.

[0002]

2. Description of the Related Art Conventionally, in a heat-insulated engine using ceramics as a heat insulating material or a heat-resistant material, when a sub-chamber type combustion chamber is formed, a sub-chamber and a suction / exhaust port are formed in a cylinder head structure. When the sub-chamber and the intake / exhaust port formed in the metal cylinder head are configured in a heat-insulating structure, the wall portion made of ceramics that insulates the sub-chamber and the wall portion made of ceramics that insulates the intake / exhaust port comprise a cylinder. In general, the head is configured to be incorporated in a head.

A heat-insulating engine using ceramics as a heat-insulating material or a heat-resistant material is disclosed, for example, in Japanese Patent Laid-Open Publication No. Hei 2-3
No. 3454 discloses this. The insulated engine is
A main combustion chamber composed of a high-density ceramic thin member fitted to the cylinder head via a heat insulating material, a sub-combustion chamber composed of a high-density ceramic thin member on the inner wall surface of a low-thermal-conductivity sub-chamber block; It comprises an access passage communicating the combustion chamber with the main combustion chamber, and a fuel injection nozzle arranged in the sub combustion chamber. In addition, the heat-insulated engine has a main combustion chamber formed integrally with a head lower surface thin plate made of high-density ceramic and a liner thin plate facing the lower surface of the cylinder head, and the liner thin plate is fitted to the upper portion of the cylinder made of a low thermal conductive material. ing.

[0004]

[SUMMARY OF THE INVENTION Incidentally, the adiabatic engine, because the cylinder inner wall becomes high, typically the combustion gas temperature is a high temperature compared to conventional water-cooled engine, therefore, also increases the amount of the NO _X I do. When fuel is burned in the combustion chamber, the generation of NO _X is determined by the combustion temperature and the fuel equivalence ratio between fuel and air, and NO _X is generated by burning the fuel at a low combustion temperature and rich in fuel. Can be reduced.

[0005] As described above, the adiabatic engine, since the combustion temperature is high, as a measure to reduce the production of NO _X, it is effective to combust the fuel-rich. In addition, when the combustion temperature is high, it is effective to use a sub-chamber engine as a type of engine structure in order to perform fuel-rich combustion. To increase the combustion speed of the sub-chamber to the same level as that of the direct-injection combustion chamber when the engine is configured as a sub-chamber,
It is necessary to increase the passage cross-sectional area of the communication hole that connects the sub-chamber and the main chamber. However, if the passage cross-sectional area of the communication hole is increased, the speed of jetting out from the sub-chamber to the main chamber is reduced, and combustion in the main chamber is not sufficiently performed.

Therefore, in order to cope with a decrease in the speed of jetting out of the sub-chamber to the main chamber, the sub-chamber is arranged at the center of the cylinder, the communication hole is opened at the center of the cylinder, and the communication hole is opened from the communication hole to the entire cylinder. When the distance and the distance are shortened and the flame and the air-fuel mixture ejected from the communication hole are mixed and burned with the fresh air existing in the main chamber, the combustion in the main chamber becomes effective and the combustion time can be shortened. However, in this case, since the sub-chamber is located at the center of the cylinder, the effective area of the intake / exhaust port in which the intake / exhaust valve is arranged becomes a problem. That is, since the sub-chamber is located at the center of the cylinder, it is necessary to arrange a wall surface that insulates the sub-chamber and a wall surface that insulates the air-intake and exhaust ports, respectively. However, the diameter becomes small, and a sufficient effective area cannot be secured.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and a sub-chamber and a port are formed in a heat insulating block made of low thermal conductivity ceramic such as aluminum titanate, and the sub-chamber and the port are connected to each other. It is an object of the present invention to provide a heat-insulating engine having a sub-chamber, characterized in that the wall to be formed is shared and made to correspond to a thin wall, and the port is formed as large as possible.

[0008]

The present invention is configured as follows to achieve the above object. That is, the present invention provides a heat insulating block made of a low heat conductive material which is fitted into a hole formed in a cylinder head and has a sub-chamber at a central portion and a plurality of ports formed around the sub-chamber. A head liner made of a high-temperature and high-strength ceramic formed of a head lower surface portion and a liner upper portion of an integrated structure fitted into the hole, and a sub-chamber lower portion communicating with the sub-chamber formed on the head lower surface portion; The present invention relates to a heat-insulated engine having a sub-chamber having a communication hole communicating therewith and a port lower portion having a valve seat communicating with the port.

Further, in the heat insulating engine having the sub chamber, a heat insulating gasket is interposed between the heat insulating block and the headliner.

In the adiabatic engine having the sub-chamber, in the type operating in four strokes, the ports formed in the cylinder head function as an exhaust port and an intake port.

In the adiabatic engine having the sub-chamber, in the type operating in two strokes, the port provided in the cylinder head is an exhaust port, and the scavenging port is formed below the cylinder of the cylinder block.

[0012]

The present invention is configured as described above and operates as follows. That is, since the heat-insulated engine having this sub-chamber has a sub-chamber and a plurality of ports formed around the sub-chamber at the center in the hole formed in the cylinder head and fitted with the heat-insulating block made of a low heat conductive material. The heat insulation block can be formed so as to share the wall of the sub-chamber and the wall of the port, and the port can be formed as large as possible. A headliner made of a high-temperature and high-strength ceramic is fitted into the hole below the heat-insulating block via a gasket, so that the heat-insulating block is securely and firmly fixed in the hole of the cylinder head. can do. Moreover, a communication hole having a sufficiently large passage cross-sectional area can be formed in the headliner.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a heat insulating engine having a sub-chamber according to the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of an insulated engine having a sub-chamber according to the present invention, and is a cross-sectional view taken along line BB of FIG. 2, and FIG. 2 shows the headliner of the insulated engine of FIG. It is sectional drawing.

The insulated engine having the sub-chamber shown in FIG.
It is operated in a stroke, that is, in four cycles, and four functions of a suction stroke, a compression stroke, a combustion stroke, and an exhaust stroke are performed in four strokes of the piston. The insulated engine having this sub-chamber is a cylinder block 6 made of a metal material such as aluminum or an aluminum alloy, and a cylinder made of a metal material such as an aluminum alloy fixed to the cylinder block 6 with a gasket 19 such as a metal gasket interposed therebetween. It has a head 5. Holes 26 corresponding to the number of cylinders of the engine are formed in the cylinder block 6, and a cylinder liner 29 forming the cylinder 23 constituting the main chamber 1 is fitted into the hole 26. The cylinder head 5 has holes 2 corresponding to the number of cylinders of the engine, that is,
0 is formed. A piston (not shown) is incorporated in the cylinder 23 formed by the cylinder liner 29 so as to reciprocate. A fuel injection nozzle 10 having multiple injection holes 24 is attached to the cylinder head 5.

The heat-insulated engine having the sub-chamber has a feature in the structure of the cylinder head 5. A number of holes 20 corresponding to each cylinder are formed in the cylinder head 5, and the heat insulating blocks 4 made of a low heat conductive material are formed in the holes 20.
Is inserted. The heat insulating block 4 has a sub-chamber 2 in the center, a plurality of (two in FIG. 2) exhaust ports 11 and intake ports 16 around the sub-chamber 2, and fuel is injected into the sub-chamber 2. A hole 30 through which the fuel injection nozzle 10 penetrates is formed so as to open the multi-injection hole 24 at the upper center in the sub-chamber 2. Further, the headliner 3 constituting the main chamber 1 is fitted in the hole 20 located below the heat insulating block 4. The head liner 3 is made of a high-temperature, high-strength ceramic integrally formed with a head lower surface portion 9 and a liner upper portion 8. In the head lower surface 9, a sub-chamber lower part 13 communicating with the sub-chamber upper part 12 of the sub-chamber 2 and a communication hole 7 communicating with the sub-chamber lower part 13 are formed, and communicate with the exhaust port 11 and the intake port 16. And a valve seat 25 formed under the port. In this embodiment, the effective passage area of the communication hole 7 is formed as large as possible. Therefore, the multiple injection holes 2 of the fuel injection nozzle 10
The fuel injected from 4 collides with the wall surface of the upper subchamber 12, rides on a swirl flow formed in the subchamber 2, and promotes mixing. It can reduce the occurrence of the NO _X in the combustion.

In the heat insulating engine having this sub chamber, a heat insulating gasket 18 is interposed between the heat insulating block 4 and the headliner 3. A gasket 28 is interposed between the periphery of the ends of the intake / exhaust ports 11 and 16 of the heat insulating block 4 and the cylindrical side surface of the hole 20 of the cylinder head 5. Is communicated to. Further, a gasket 17 is interposed between the inner wall surface of the cylinder head 5 and the outer wall surface of the head liner 3,
In addition, a heat insulating air layer 27 is formed. Exhaust port 11
An exhaust valve 14 that is operated by a valve guide guided by a valve guide 21 is disposed on a valve seat 25 of the intake port 1. An intake valve 1 that is operated by a valve guide guided by the valve guide 21 is disposed on a valve seat 25 of the intake port 16.
5 are arranged.

The heat insulating block 4 is made of a ceramic having a low thermal conductivity such as aluminum titanate Al ₂ TiO ₅ . That is, the heat-insulating block 4 is formed as a block having an integral structure in which the sub-chamber 2 and the intake / exhaust ports 11 and 16 are formed, and the wall that separates the sub-chamber 2 and the intake / exhaust ports 11 and 16 is shared. It is structured to be. In the heat-insulated engine having the sub-chamber, the size of the sub-chamber 2 is determined by the compression ratio or the volume ratio between the main chamber 1 and the sub-chamber 2, and the boundary wall can be formed as thin as possible. Therefore, the passage cross-sectional area of the intake / exhaust ports 11, 16 can be made as large as possible, and a sufficient effective area can be secured. Therefore, in the heat-insulated engine having this sub-chamber, sufficient air can be introduced through the intake port 16, and exhaust gas can be reliably and rapidly discharged through the exhaust port 11.

Further, in the heat-insulated engine having this sub-chamber,
The communication hole 7, which communicates the sub-chamber 2 formed in the heat insulating block 4 and the main chamber 1 formed in the head liner 3, can have a large passage cross-sectional area, and can increase the combustion speed as compared with the direct injection combustion chamber. Can be equally fast. Therefore, the combustion speed can be increased with fuel rich in the sub-chamber 2,
Combustion that reduces the generation of NO _X can be performed.
In addition, the speed at which the combustion gas of the flame and the air-fuel mixture flowing from the sub-chamber 2 to the main chamber 1 through the communication hole 7 is discharged from the communication hole 7
However, since the communication hole 7 is located at the center with respect to the main chamber 1, the distance from the communication hole 7 to the entire cylinder 23 decreases, and The flame and air-fuel mixture ejected through the communication hole 7
The combustion speed can be shortened by mixing with fresh air around the inside in a short time. Therefore, it is possible to perform the combustion to reduce the generation of the NO _X in the combustion in the main combustion chamber 1.

Next, another embodiment of a heat insulating engine having a sub-chamber according to the present invention will be described with reference to FIG. The insulated engine of this embodiment is different from that of the above embodiment in that the cylinder liner 7 fitted in the hole 26 of the cylinder block 6
Since the structure is the same except that the scavenging port 22 is formed in the lower part of the drawing, the same components are denoted by the same reference numerals, and redundant description will be omitted. This adiabatic engine is operated in two strokes, that is, two cycles, and four functions of suction, compression, combustion, and scavenging / exhausting are performed in two strokes of the piston. In the heat-insulated engine having this sub-chamber, the four ports formed in the cylinder head 5 function as the exhaust ports 11. An exhaust valve 14 is disposed in a valve seat 25 formed at an inlet of the exhaust port 11 formed in the headliner 3. Also,
A scavenging port 22 is formed below the cylinder liner 29 fitted in the hole 26 of the cylinder block 6.

In this two-stroke adiabatic engine, the exhaust valve 14 is disposed on the cylinder head 3 so that the scavenging action is performed by airflow in a certain direction with respect to the cylinder center line.
This is applied to the uniflow type with improved engine efficiency. In this two-stroke engine,
A plurality of scavenging port openings, that is, scavenging ports 22 are formed in the lower part of the cylinder liner 29 fitted in the cylinder block 6 in the circumferential direction.
Numeral 2 communicates with an annular transfer passage formed in the cylinder block 6. The scavenging port 22 is always in communication with the annular scavenging passage. Further, the annular transfer passage communicates with the intake passage. The air from an air cleaner, a crankcase, a turbocharger, a mechanical supercharger, or the like is fed into the intake passage. The piston is configured to reciprocate in a cylinder 23 formed by the cylinder liner 29. The top surface of the piston head is the scavenging port 22
Of the cylinder 2
3 is introduced. In the adiabatic engine of this embodiment, N
The function of reducing the generation of O _X are the same as those of the above embodiment.

[0021]

The heat-insulating engine having the sub-chamber according to the present invention is configured as described above, and has the following effects. The heat-insulating engine having this sub-chamber has a sub-chamber in the center and a heat-insulating block made of a low thermal conductive material having a plurality of ports formed around the sub-chamber, which is fitted into a hole formed in the cylinder head. Since the head liner made of high-temperature and high-strength ceramics integrally formed with the lower surface of the head and the upper portion of the liner is fitted into the lower hole, a structure that shares the wall separating the sub-chamber and the port can be configured. The wall can be formed thin to increase the effective passage area of the port.

Therefore, in this heat-insulated engine, the effective area of the communication hole communicating the sub-chamber and the main chamber can be made large, and the combustion state in the sub-chamber is fuel-rich and is equivalent to that of the direct injection combustion chamber. Combustion speed can be secured, and generation of NO _X can be suppressed. In addition, since the auxiliary chamber is formed in the center of the cylinder and the distance between the flame and the air-fuel mixture ejected from the auxiliary chamber becomes shorter than the fresh air existing on the entire circumference of the cylinder, the mixing in the main chamber is reduced. Is promoted, the combustion speed can be increased, the combustion period can be shortened, and combustion capable of suppressing the generation of NO _X can be performed. In particular, by sharing the wall separating the sub-chamber and the port, a sufficient passage cross-sectional area of the port can be ensured, sufficient air can be introduced into the cylinder in the suction stroke, and the exhaust stroke in the exhaust stroke. It is possible to provide a structure that can discharge gas reliably and promptly and that can respond sufficiently.

In the heat-insulating engine having the sub-chamber, since the heat-insulating gasket is interposed between the heat-insulating block and the headliner, the cylinder head and the cylinder block are separated from each other by the heat-insulating block and the headliner. By inserting and fixing, the heat-insulating gasket can absorb the gap between the heat-insulating block and the headliner, there is no play, and both can be securely and firmly fixed in the cylinder head. .

The heat-insulating engine having this sub-chamber
When operated by a stroke, the plurality of ports formed in the cylinder head can be configured to function as a plurality of exhaust ports and a plurality of intake ports, sufficiently taking in intake air into the cylinder, and Exhaust gas can be discharged reliably and quickly.

Alternatively, the insulated engine having this sub-chamber
When operated in two strokes, all of the ports provided in the cylinder head function as exhaust ports, and the scavenging port is formed below the cylinder of the cylinder block. Although necessary, the effective area of the passage can be sufficiently ensured, the exhaust gas can be reliably and quickly discharged, and sufficient intake air can be taken into the cylinder from the scavenging port.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a heat insulating engine having a sub-chamber according to the present invention, taken along line BB of FIG. 2;

FIG. 2 shows a liner AA of the headliner of the heat-insulated engine of FIG.
It is sectional drawing seen from.

3 shows another embodiment of the heat-insulated engine having a sub-chamber according to the present invention, and is a cross-sectional view taken along line BB of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main chamber 2 Sub chamber 3 Head liner 4 Insulation block 5 Cylinder head 6 Cylinder block 7 Communication hole 8 Upper liner 9 Head lower part 10 Fuel injection nozzle 11 Exhaust port 12 Upper sub chamber 13 Lower sub chamber 14 Exhaust valve 15 Intake valve 16 Intake port 18 Insulated gasket 20 Hole 22 Scavenging port 23 Cylinder 25 Valve seat

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification code FI F02B 19/14 F02B 19/14 B 19/16 19/16 C (58) Fields investigated (Int.Cl. ⁷ , DB name) F02F 1/24 F01L 1/00 F01L 3/02 F02B 19/14 F02B 19/16

Claims (4)

(57) [Claims] 1. A heat insulating block which is fitted into a hole formed in a cylinder head and is made of a low heat conductive material having a sub-chamber at a center portion and a plurality of ports formed around the sub-chamber, and the hole below the heat insulating block. A head liner made of a high-temperature and high-strength ceramic formed of an integrated lower surface portion of the head and an upper portion of the liner, and a lower sub-chamber communicating with the sub-chamber formed on the lower surface portion of the head, and communicating with the lower sub-chamber. An insulated engine having a sub-chamber having a communication hole and a lower port having a valve seat communicating with the port. 2. The heat-insulating engine having a sub-chamber according to claim 1, wherein a heat-insulating gasket is interposed between the heat-insulating block and the head liner. 3. The adiabatic engine having a sub-chamber according to claim 1, wherein in a type operating with four strokes, the ports formed in the cylinder head are an exhaust port and an intake port. 4. The sub-chamber according to claim 1, wherein in the two-stroke type, the port provided in the cylinder head is an exhaust port, and the scavenging port is formed in a lower portion of the cylinder of the cylinder block. Insulated engine.