JPH066190Y2 - Direct injection internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an internal combustion engine, and more particularly to a direct injection internal combustion engine of the type in which fuel is directly injected into a combustion chamber.

[Conventional technology]

In the direct injection type engine, it is necessary to efficiently generate the air-fuel mixture in a short time, and the production efficiency of the air-fuel mixture greatly affects the combustibility of the engine. As a method of improving combustion in a direct injection diesel engine, an auxiliary cylinder is formed in the cylinder head, and an auxiliary piston that is reciprocally movable inside this is pushed into the air combustion chamber at the end of fuel injection to generate air flow. A method has already been proposed (Japanese Patent Laid-Open No. 59-110829).

[Problems to be solved by the invention]

However, in the conventional method as described above, the force for pushing the air into the combustion chamber is due to the movement of the auxiliary piston, and since the speed of the auxiliary piston is limited, the air flow generated in the combustion chamber is weak, and There was a problem that sufficient combustion improvement could not be obtained.

[Means for solving problems]

In order to solve such problems, according to the present invention,
In a direct injection internal combustion engine having a fuel injection nozzle for forming a combustion chamber between a top of a piston that reciprocates in a cylinder and a cylinder head, and injecting fuel directly into the combustion chamber from the cylinder head side, An auxiliary cylinder is formed inside the auxiliary cylinder, and an auxiliary piston is provided in the auxiliary cylinder so as to be able to reciprocate. The auxiliary piston communicates only near the top dead center and the bottom dead center, and shuts off during the stroke of the auxiliary piston. Is provided with a drive means for communicating the working chamber of the auxiliary cylinder with the combustion chamber by means of a passage means that reciprocates the auxiliary piston in synchronism with the stroke of the engine, and strokes the air sucked into the working chamber at one end of the stroke of the auxiliary piston. Is compressed while moving to the other end side of the auxiliary cylinder, and is compressed from the working chamber of the auxiliary cylinder at the end of fuel injection through the passage means opened at the other end side. Direct injection type internal combustion engine so as to push the air into the chamber are provided.

[Action]

Near the top dead center of the auxiliary piston, the air in the combustion chamber flows into the working chamber of the auxiliary cylinder through the passage means, and while the auxiliary piston is descending, the air in the working chamber is compressed, and when it is near the bottom dead center, the compressed operation is performed. The air in the room suddenly flows into the combustion chamber at a high speed, and a strong air flow is generated in the combustion chamber to improve combustion.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, a cylinder 2 is formed in a cylinder block 1 of a diesel engine, in which a piston 3 that is reciprocally slid by a crank mechanism (not shown) is arranged. A cylinder head 4 is attached to the upper part of the cylinder block 1, and a combustion chamber 5 is formed between the top of the piston 3 and the cylinder head 4. A fuel injection nozzle 6 for directly injecting fuel from the cylinder head 4 side toward the combustion chamber 5 is attached to the cylinder head 4. In addition, 7 is an injection pipe for supplying fuel to the fuel injection nozzle 6, 8 is an exhaust valve for opening and closing an exhaust port, 9 is an exhaust port for exhausting combustion gas, and an intake port for introducing fresh air into the combustion chamber 5. Are not shown. Further, an intake valve that opens and closes the intake port is also omitted in the drawing.

In the present invention, the auxiliary cylinder 11 is provided inside the cylinder head 4.
The auxiliary piston 12 is disposed in the auxiliary cylinder 11 so as to be capable of reciprocating sliding. The auxiliary cylinder 11 below the auxiliary piston 12 is defined as a working chamber 11a. The upper portion of the auxiliary piston 12 extends upward and contacts one end of a rocker arm 14 swingably attached to the shaft 13. The other end of the rocker arm 14 is in contact with the push rod 15, and the operation of the cam shaft (not shown) is transmitted. A spring 16 is provided to urge the auxiliary piston 12 upward so as to maintain constant contact with the rocker arm 14.

As shown in FIG. 1, when the auxiliary piston 12 is in the position near the top dead center, the first communication hole provided inside the cylinder head 4 for communicating between the combustion chamber 5 and the working chamber 11a of the auxiliary cylinder 11. 21 has one end opened to the combustion chamber 5 and the other end opened to the side surface of the auxiliary cylinder 11. In addition, the second communication hole 2
2 has one end opening to the lower surface of the auxiliary piston 12, that is, the working chamber 11a of the auxiliary cylinder 11, and the other end opening to the side surface of the auxiliary piston 12, and as shown in FIG. The positions of the first communication hole 21 and the first communication hole 21 are mutually aligned. The working chamber 11a of the auxiliary cylinder 11 is sealed by an oil ring 16.

During the intake stroke of the engine, the piston 3 moves downward, an intake valve (not shown) opens, and fresh air is introduced into the cylinder 2 through an intake port (not shown). Fresh air is given a swirling motion (swirl) due to the shape of the intake port, as is normally done in direct injection diesel engines. During this intake stroke, the auxiliary piston 12 slowly moves upward due to the movements of the spring 16 and the rocker arm 14, and the lower working chamber 11 of the auxiliary cylinder 11 moves.
Fresh air also flows into a through the first communication hole 21.

When the compression stroke is entered and the intake valve (not shown) is closed,
As the piston 3 rises, the pressure inside the engine cylinder 2 begins to rise. The auxiliary piston 12 remains at the position of the top dead center during this compression stroke. Therefore, as the pressure in the cylinder 2 rises, the pressure in the working chamber 11a of the auxiliary cylinder 11 also rises. Since the pressure value is slightly lower than the pressure value in the cylinder 2 because of the presence of the first communication hole 21, it is almost equal to the pressure in the cylinder 2. Immediately before the piston 3 fully rises,
At a proper crank angle, the high-pressure fuel pressure-fed from the injection nozzle 6 through the injection pipe 7 from the injection pump (not shown) is injected into the combustion chamber 5. The injected fuel begins to burn from a portion having an appropriate temperature and oxygen concentration, but as is well known, in a portion lacking oxygen, the fuel causes incomplete combustion and produces black smoke. The generated black smoke is oxidized and recombusted when it comes out with high temperature oxygen in the cylinder 2. Only the difference between the produced black smoke and the oxidized black smoke is emitted from the engine during the exhaust stroke. This state is shown in the third.
The amount of black smoke emitted from the engine largely depends on the combustion period of the engine, and if combustion is slow and combustion continues even when the exhaust valve 8 is opened, the amount of black smoke produced is as shown in FIG. Increase, and the exhaust smoke concentration increases sharply. It is well known that air flow is effective for faster combustion.

In the present invention, as described above, the air accumulated in the auxiliary cylinder 11 is lowered by the movement of the rocker arm 14 by the action of the cam (not shown) of the auxiliary piston 12 which has risen in the auxiliary cylinder 11, and during the first period Also, both the second communication holes 21 and 22 are compressed by being blocked by the auxiliary piston 12 and the auxiliary cylinder 11. Further, when the auxiliary piston 12 descends, the first communication hole 21 and the second communication hole 22 communicate with each other, and as shown in FIG. 2, the compressed air is vigorously stronger than the working chamber 11a of the auxiliary cylinder 11. To inject.

[Effect of device]

As described above, according to the present invention, the air compressed at the end of the stroke of the auxiliary piston is injected from the working chamber of the auxiliary cylinder into the combustion chamber all at once, so that a sufficient amount of auxiliary air can be secured and the combustion period Since a strong air flow can be provided inside the combustion chamber 5, the swirl provided by the intake port in the intake stroke can be low, which can increase the volumetric efficiency. Since the swirl ratio at the time of fuel injection is low, the amount of combustible air-fuel mixture prepared during the ignition delay period is small, and the amount of fuel burned at one time during ignition is small, so the NO generation amount is reduced. For the same reason, combustion impact is reduced and combustion noise is reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a combustion chamber of a direct injection internal combustion engine according to the present invention, FIG. 2 is a diagram showing a state when an auxiliary piston is descending, and FIG. 3 is a diagram showing a black smoke producing state at the time of combustion. . 2 ... Cylinder, 3 ... Piston, 4 ... Cylinder head, 5 ... Combustion chamber, 6 ... Fuel injection nozzle, 11 ... Auxiliary cylinder, 12 ... Auxiliary piston, 21, 22 ... Communication holes.

Claims (3)

[Scope of utility model registration request] 1. A direct injection internal combustion engine having a fuel injection nozzle for forming a combustion chamber between a top of a piston that reciprocates in a cylinder and a cylinder head, and injecting fuel directly into the combustion chamber, An auxiliary cylinder is formed in the cylinder head, and an auxiliary piston is provided in the auxiliary cylinder so as to be able to reciprocate, and the auxiliary piston communicates only near the top dead center and the bottom dead center of the auxiliary piston and in the middle of the stroke of the auxiliary piston. In this case, a drive means for connecting the working chamber of the auxiliary cylinder and the combustion chamber to each other by a passage means that is shut off and reciprocating the auxiliary piston in synchronism with the stroke of the engine is provided. Air is compressed in the process of moving to the other end side of the stroke, and is combusted from the working chamber of the auxiliary cylinder at the end of fuel injection through the passage means opened at the other end side. Direct injection type internal combustion engine so as to push the air to. 2. The passage means has a first communication hole formed inside a cylinder head, one end of which is opened to the combustion chamber and the other end of which is opened to a side surface of the auxiliary cylinder, and one end is opened to the auxiliary cylinder working chamber and the other end is The second communication hole is formed inside the piston and is opened to the side surface of the piston. The first communication hole directly communicates with the auxiliary cylinder working chamber near the top dead center of the auxiliary piston, and the second communication hole near the bottom dead center. The internal combustion engine according to claim 1, wherein the utility model is registered so as to communicate with the auxiliary cylinder working chamber via the. 3. The internal combustion engine according to claim 1, wherein the driving means for the auxiliary piston is operated in synchronization with the camshaft.