JP3168583B2 - Engine with subchamber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine with a sub-chamber in which a main chamber is formed in a piston head and a sub-chamber is formed in a cylinder head.

[0002]

2. Description of the Related Art Conventionally, a combustion chamber of an engine is represented by a direct injection type and a sub-chamber type. The combustion chamber of the sub-chamber type achieves the mixing of fuel oil droplets and air by the high swirl formed in the sub-chamber, forming a fuel-rich mixture.
Combustion that can suppress generation of NO _X can be ensured.

Further, Japanese Utility Model Laid-Open No. 49-36315 discloses an internal combustion engine with a sub-combustion chamber in which the injection hole area of the sub-combustion chamber is variably controlled. The internal combustion engine with a sub-combustion chamber has a fixed orifice at a crank angle other than the top dead center and before and after the top dead center due to a projection or recess provided on the upper surface of the piston and a recess or projection provided on the cylinder head itself. The area with the area is reduced to the area reduced at the top dead center of the crank angle or the nozzle is closed, and after the top dead center is restored to the original nozzle area, or the crank angle before and after the top dead center is fixed. During the period, the nozzle has a certain reduced orifice area or closes the orifice, and then recovers based on the orifice area.

[0004]

However, in the combustion chamber of a conventional engine with a sub-chamber, the area of the communication hole that communicates between the sub-chamber formed in the cylinder head and the main chamber formed on the piston side is limited. A variable throttle structure that is constant or simply increased by the downward movement of the piston. In addition, the conventional combustion chamber structure of the engine with the sub-chamber has a structure in which the timing of the outflow of the partial combustion gas, that is, the flame and the air-fuel mixture from the sub-chamber to the main chamber cannot be controlled.

Further, the internal combustion engine with a sub-combustion chamber in which the injection hole area of the sub-combustion chamber is variably controlled as disclosed in Japanese Utility Model Laid-Open Publication No. 49-36315 discloses that the communication hole is opened when the piston descends. It has the effect of delaying the outflow of gas from the sub-chamber to the main chamber until a certain time, but it cannot be closed again after opening the communication hole when the piston descends. When the communication hole is opened again, the direction in which the partial combustion gas is blown out cannot be changed.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem. The area of a communication hole communicating a sub-chamber with a main chamber is variably configured as the piston descends, and the sub-chamber is connected to the main chamber. The timing of the outflow of the flame and the mixture, ie, the partial combustion gas, is controlled. In particular, the outflow timing from the sub-chamber to the main chamber is delayed to ensure a sufficient combustion period in the sub-chamber, and the fuel is burned in the sub-chamber in a fuel-rich manner. , auxiliary chamber to the main by air flow in the room to facilitate mixing to ensure the relative speed between the fresh air in the main chamber and the effluent gas to reduce the generation of the NO _X to maintain good combustion and engine performance To provide an engine with

[0007]

The present invention is configured as follows to achieve the above object. That is,
The present invention relates to a sub-chamber formed on a cylinder head and having a fuel injection nozzle, and a sub-chamber having a cylinder head-side annular protruding portion formed in a circumferential direction and having a slit protruding from the lower surface of the cylinder head and communicating between the inside and the outside. A piston-side annular protrusion provided in a piston head having a slit formed in a circumferential direction and capable of being fitted to the cylinder-head-side annular protrusion near the top dead center of the piston and communicating the inside and the outside; And a main chamber formed in the piston head outside the piston-side annular protrusion, wherein the slit is one of the slits formed in the cylinder-head-side annular protrusion and the piston-side annular protrusion. Are formed in two rows in the reciprocating direction of the piston, and are formed on one of the annular protrusion on the cylinder head side and the annular protrusion on the piston side. Two rows wherein the slits of the related sub-chamber with the engine consisting be formed in different positions in the circumferential direction.

[0008]

Since the sub-chamber engine according to the present invention is constructed as described above, it is possible to sufficiently delay the outflow of gas from the sub-chamber to the main chamber while ensuring a sufficient combustion period in the sub-chamber. NO _X and maintain can be, favorable combustion and performance
Can be reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an engine with a sub-chamber according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of an engine with a sub-chamber according to the present invention, FIG. 2 is a schematic perspective view for explaining the relationship between a piston and a communication hole in FIG. 1, and FIG. 3 is a main chamber in FIG. FIG. 2 is a schematic plan view illustrating a combustion state in the fuel cell.

As shown in FIG. 1, this engine with a sub-chamber comprises a cylinder block 9, a cylinder head 3 fixed to the cylinder block 9 via a head gasket, and a cylinder fitted in a hole formed in the cylinder block 9. 10
, A piston 1 reciprocating in a cylinder 10 formed by the cylinder liner, a main chamber 2 formed in a piston head 8 of the piston 1, a hole 16 of a cylinder head 3 and a sub-chamber 5. And a fuel injection nozzle 4 arranged in the sub-chamber 5 and a communication hole 7 for communicating the sub-chamber 5 with the main chamber 2. The cylinder head 3 has an intake port and an exhaust port. An intake valve is disposed at the intake port, and an exhaust valve is disposed at the exhaust port.

In this engine with a sub-chamber, in particular, as shown in an enlarged manner in FIG. 6, the communication hole 7 communicating the main chamber 2 and the sub-chamber 5 is extended so as to protrude from the lower surface 18 of the cylinder head. A slit 12 is provided with an annular protrusion 17 on the head side, which communicates inside and outside with the annular protrusion 17 on the cylinder head side.
Are formed in the circumferential direction, and slits 13 and 14 that can be fitted to the cylinder head-side annular protrusion 17 near the top dead center of the piston 1 and communicate with the inside and outside are provided in the piston head 8 formed in the circumferential direction. It has a piston-side annular protrusion 9. The main chamber 2 is formed in the piston head 8 outside the piston-side annular protrusion 9.

In FIG. 1, the slits 12 are formed in the annular protrusion 17 on the cylinder head side in one step or one row, and the slits 13 and 14 are formed in the annular protrusion 9 on the piston side in two steps or two in the reciprocating direction of the piston. Formed in columns. Piston 1
The slit 12 is first aligned with the slit 14 to open the communication hole 7, ie, the sub-chamber 5, to the main chamber 2, and then the slit 12 is aligned with the slit 13, and the communication hole 7, ie, the sub-chamber 5 is aligned with the main chamber 2. Open to Or, in some cases,
Although not limited to the above structure, not shown, for example, slits are formed in the piston-side annular protrusion 9 in one step, that is, in one row in the reciprocating direction of the piston, and the cylinder head-side annular protrusion 1 is formed.
7, the slits can be formed in two stages, that is, two rows in the reciprocating direction of the piston. In this case, the slit of the piston-side annular protrusion 9 is formed by the cylinder head-side annular protrusion 17.
To the upper slit, and then to the lower slit.

Further, in FIG. 1, the slits 12 are formed in one row in the annular protrusion 17 on the cylinder head side, and the slits 13 and 14 are formed in two rows in the annular protrusion 9 on the piston side. Are formed at different positions in the circumferential direction. In this case, the circumferential length of the slit 12 is increased, ie, the slit 13 and the slit 14 are increased.
The slit 12 is aligned with both the slit 13 and the slit 14 so that the sub-chamber 5 and the main chamber 2 can communicate with each other. Therefore, as shown in FIG. 3, the position of alignment with the slit 12 differs depending on the position where the slit 13 and the slit 14 are formed, and the flame and air-fuel mixture blown out from the sub-chamber 5, that is, the communication hole 7 to the main chamber 2. The air is blown out to different areas of the main room 2. Or, in some cases, not limited to the above structure,
Although not shown, for example, slits are formed in the piston side annular protrusion 9 in one row, and slits are formed in the cylinder head side annular protrusion 17 in two rows. They may be formed at different positions in the circumferential direction.

The engine with a sub-chamber according to the present invention is configured as described above, and operates as follows. In this sub-chamber engine, fresh air is introduced into the sub-chamber 5 from the cylinder 10 through the communication hole 7 when the piston 1 rises in the compression stroke, and the intake air is compressed. Fuel from the fuel injection nozzle 4 is injected into the auxiliary chamber 5 at the compression stroke end of the piston 1, combustion while suppressing the occurrence of the NO _X in the fuel-rich condition progresses. At this time, the flow velocity and the outflow timing of the gas flowing out of the sub chamber 5 to the main chamber 2 follow the trajectory of the outflow gas indicated by the symbol C in FIG. That is, the sub-chamber 5 and the main chamber 2 are initially in a state in which the slits 12 and the slits 14 are slightly communicated, and the communication hole 7 is in a state where the opening is narrowed.
Then, when the piston 1 descends, the alignment between the slits 12 and the slits 14 is completed, the opening area increases, and the flow velocity also increases. As shown by the symbol A in FIG. The flame and the air-fuel mixture are blown into the chamber 2 through the communication hole 7 and the opening formed by the slits 12 and 14.

As the piston 1 continues to descend, the slit 12 and the slit 14 are brought into a non-aligned state,
And the main chamber 2 are temporarily in a non-communicating state, that is, a closed state, and the slits 12 and 13 start to be aligned. Accordingly, the combustion period in the sub chamber 5 is sufficiently ensured, and the outflow timing of the flame and the mixture, that is, the partial combustion gas, to the main chamber 2 can be sufficiently delayed. Therefore, the combustion period in the sub-chamber 5 is extended, so that the combustion in which NO _X is suppressed can be performed for a long time. Then, as indicated by reference numeral E in FIG. 3, the gas flowing out of the sub chamber 5 into the main chamber 1 is diffused in the main chamber 2 and generates a good air-fuel mixture while entraining fresh air existing in the main chamber 2. perform combustion in the main chamber 2 in a state in which the temperature was reduced Te, continued combustion with suppressing generation of NO _X.

FIG. 7 plots the outflow timing T on the horizontal axis and the flow velocity V on the vertical axis, and shows the relationship between the outflow timing T and the flow velocity V. Reference symbol F relates to a fuel injection nozzle having a single communication hole, such as a conventional fuel injection nozzle, reference symbol C indicates the relationship between the outflow gas of the fuel injection nozzle according to the present invention, and reference symbol D.
FIG. 4 shows the relationship of the late outflow gas of the fuel injection nozzle according to the present invention. Then, as the piston 1 continues to descend, the trajectory of the late outflow gas indicated by the symbol D in FIG. 7 follows, and the slit 12 and the slit 13 are completely aligned, and the sub chamber 5 and the main chamber 2 Means slit 12
To the main chamber 2 from the auxiliary chamber 5 again through the communication hole 7 and the slit 1.
It is blown out through the opening of the slit 2 and the slit 13. At this time, the outflow gas diffuses into the main chamber 2 and forms a return flow toward the center in a state where the flow velocity is reduced while the direction is changed by the outer peripheral wall 20 of the main chamber 2. . Therefore, the late-stage outflow gas of the flame and the air-fuel mixture blown out from the sub-chamber 5 to the main chamber 2 through the opening formed by the alignment of the slit 12 and the slit 13 is generated during the return flow of the first-stage outflow gas, that is, during the gas flow. The gas is blown out, the relative velocity between the late effluent gas and the early effluent gas is ensured, a relative flow is formed between the two gases, and the mixing is promoted and the combustion is performed well. Moreover, since the combustion temperature is reduced, it is possible to ensure the combustion while suppressing the generation of NO _X.

On the other hand, in the case of a structure having a single communication hole, such as a conventional fuel injection nozzle, the pattern is as shown by the symbol F in FIG. 7, and almost no relative speed is generated.

FIGS. 4 and 6 show another embodiment of the engine with a sub-chamber according to the present invention. The engine with the sub-chamber of this embodiment has the same configuration and the same structure as the engine with the sub-chamber except that the insertion relationship between the cylinder head side annular projection and the piston side annular projection is reversed. Since they have the same function, the same parts are denoted by the same reference numerals, and redundant description will be omitted.

[0019]

The engine with a sub-chamber according to the present invention is constructed as described above, so that the slit of the cylinder head side annular projection and the piston of the piston side annular projection are aligned with each other. The opening area of the communication hole communicating the sub-chamber and the main chamber can be made variable as the piston descends, and the outflow timing of the flame and the mixture, that is, the partial combustion gas, from the sub-chamber to the main chamber can be adjusted. You can control. In particular, the outflow time from the sub-chamber to the main chamber is delayed to secure a sufficient combustion period in the sub-chamber, fuel-rich combustion is performed in the sub-chamber, and the outflow gas and fresh air in the main chamber are caused by the air flow in the main chamber. to promote mixing to ensure the relative speed between the, as well as reduce the occurrence of the NO _X to maintain good combustion and engine performance, unburned gas, generation of carbon or the like can be suppressed.

In particular, one of the slits formed in the cylinder-head-side annular protrusion and the piston-side annular protrusion is formed in two rows in the reciprocating direction of the piston. The former effluent gas and the latter effluent gas are formed in the effluent gas blown to the air, and the latter effluent gas is blown out in the return flow of the former effluent gas in the main chamber to form a relative flow between the two, and the blown flame And the mixture of air and the partial combustion gas with air is promoted, and good combustion can be performed.

Furthermore, the two rows of slits formed in either the cylinder head-side annular protrusion or the piston-side annular protrusion are formed at different positions in the circumferential direction from each other, so By changing the region and the blowout region of the late outflow gas, the late outflow gas can be reliably blown out in the return flow of the first outflow gas, and the partial combustion gas and air can be mixed well.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an engine with a sub-chamber according to the present invention.

FIG. 2 is a schematic perspective view for explaining a relationship between a piston and a communication hole in FIG. 1;

FIG. 3 is a schematic plan view illustrating a combustion state in a main chamber of FIG.

FIG. 4 is a sectional view showing another embodiment of the engine with a sub-chamber according to the present invention.

FIG. 5 is an enlarged sectional view of a portion of a communication hole in FIG. 1;

FIG. 6 is an enlarged sectional view of a portion of a communication hole in FIG. 4;

FIG. 7 is a graph showing a relationship between a gas flow rate flowing from a sub chamber to a main chamber and an outflow timing.

[Explanation of symbols]

 Reference Signs List 1 piston 2 main chamber 3 cylinder head 4 fuel injection nozzle 5 sub chamber 6 sub chamber wall 7 communication hole 8 piston head 9 piston side annular protrusion 10 cylinder 12, 13, 14 slit 17 cylinder head side annular protrusion 18 cylinder head Bottom

Claims (1)

(57) [Claims] 1. A sub-chamber formed in a cylinder head and provided with a fuel injection nozzle, and a sub-chamber provided with a cylinder head-side annular protruding portion formed from a lower surface of the cylinder head and formed in a circumferential direction with a slit communicating between the inside and the outside. A communication hole communicating with the cylinder side, a piston-side annular protrusion formed in a piston head having a slit formed in the circumferential direction and capable of being fitted to the cylinder head-side annular protrusion near the top dead center of the piston and communicating the inside and the outside. , and has a main chamber which is formed outside of the piston head of the piston-side annular projecting portion, said Siri
And the piston-side annular protrusion and the piston-side annular protrusion
One of the slits formed in the
Are formed in two rows in the reciprocating direction of the piston.
And the piston-side annular protrusion and the piston-side annular protrusion
The two rows of slits formed in any one of
An engine with a sub-chamber that is formed in different positions in the direction .