JPH0835427A - Combustion chamber of auxiliary chamber-type internal combustion engine - Google Patents

Abstract

PURPOSE:To decrease the gas flow loss, so as to promote gas outflow into a main combustion chamber, and so as to decrease the fuel consumption and NOx by largely inclining the side wall on the lower part of an auxiliary combustion chamber toward the upper part, in an auxiliary chamber-type internal combustion engine wherein the auxiliary combustion chamber is communicated with the main combustion chamber through a plurality of auxiliary chamber injection ports. CONSTITUTION:In an auxiliary chamber-type internal combustion engine wherein an auxiliary combustion chamber 2 in which a fuel injection valve 5 and a glow plug are installed are communicated with a main combustion chamber 1 through a plurality of auxiliary chamber injection ports 3, the side wall on the lower part 22 of the auxiliary combustion chamber is largely inclined in the direction of the auxiliary combustion chamber upper part 21. When gas in the main combustion chamber 1 is compressed and allowed to flow to the auxiliary combustion chamber lower part 22 from the auxiliary chamber injection port 3, gas is prevented from being rapidly expanded since the opening end side of the auxiliary chamber injection port 3 is contracted, and the gas flow loss is decreased. Since the side wall of the auxiliary combustion chamber lower part 22 is largely inclined, the gas flow velocity and the mixing combustion in the auxiliary combustion chamber 2 are restrained, and NOx can be prevented from being increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion chamber of an internal combustion engine of a subchamber type.

[0002]

2. Description of the Related Art FIG. 2 shows a combustion chamber of a conventional auxiliary chamber type internal combustion engine.
It will be explained by. FIG. 2 is a sectional view of a combustion chamber of a conventional sub-chamber internal combustion engine. In the figure, the auxiliary combustion chamber 2a is installed in the cylinder head 4a. The auxiliary combustion chamber 2a has various shapes based on a cylindrical shape, a spherical shape, a truncated cone shape, etc., but the auxiliary combustion chamber 2a is based on a cylindrical shape.
A fuel injection valve 5 is installed in the auxiliary combustion chamber 2a, and a glow plug (not shown) that preheats the auxiliary combustion chamber when the engine is started is installed as necessary. The sub combustion chamber 2a communicates with the main combustion chamber 1a formed by the top surface of the piston 6a, the cylinder 7a, and the lower surface of the cylinder head 4a through the sub chamber injection port 3a. The shape of the sub-combustion chamber lower portion 22a is cylindrical and the tip is spherical.

The operation of the conventional example will be described. Air in the main combustion chamber 1a is compressed by the piston 6a during the compression stroke during engine operation and flows into the sub combustion chamber 2a through the sub chamber injection port 3a. When fuel is injected from the fuel injection valve 5a into the auxiliary combustion chamber 2a, the fuel and air are mixed and ignited and burned. Sub combustion chamber 2a
Mixing of unburned fuel and fuel ejected from the main combustion chamber 1a with air is caused by gas ejection from the auxiliary combustion chamber 2a.

[0004]

Fuel consumption of a subchamber engine, N
To improve the O _X is mixture formation combustion control of the auxiliary combustion chamber fuel and air are important. When the diameter of the auxiliary combustion chamber bottom 22a to increase the gas flow velocity of the auxiliary combustion chamber 2a is suppressed, mixing and combustion of fuel and air takes place slowly is advantageous in low NO _X reduction. However, when the gas in the main combustion chamber during the compression stroke flows into the lower portion 22a of the auxiliary combustion chamber from the outlet of the auxiliary chamber, the gas expands rapidly, resulting in a large gas flow loss and a decrease in the gas flow velocity, and the fuel and air in the auxiliary combustion chamber are reduced. Inadequate mixing and combustion.

When the burnt and unburned gases in the auxiliary combustion chamber during the expansion stroke flow from the lower portion 22a of the auxiliary combustion chamber to the auxiliary chamber injection port 3a,
Since it shrinks abruptly, it will be difficult for it to flow out and fuel consumption will deteriorate. Reducing the diameter of the auxiliary combustion chamber bottom 22a Conversely, mixing and combustion of the auxiliary combustion chamber fuel and air are activated NO _X increases. Further, the gas in the sub-combustion chamber does not easily pass through the lower part of the sub-combustion chamber and is difficult to flow out from the sub-combustion nozzle, and the fuel efficiency deteriorates.

An object of the present invention is to improve the fuel economy of a sub-chamber internal combustion engine,
(EN) A combustion chamber capable of improving mixture-forming combustion of fuel and air in the auxiliary combustion chamber to reduce NO _X, reducing gas flow loss, and promoting gas outflow to the main combustion chamber.

[0007]

According to the present invention, in a sub-chamber internal combustion engine in which the sub-combustion chamber communicates with the main combustion chamber through a plurality of sub-chamber injection holes, the side wall of the lower portion of the sub-combustion chamber is the sub-combustion chamber. It is characterized by being enlarged and inclined in the upper direction.

[0008]

Since the present invention is constructed as described above, when the gas in the main combustion chamber during the compression stroke of the engine flows from the sub chamber injection port to the sub combustion chamber lower part, the sub chamber injection port opening end of the sub combustion chamber lower part is Since the size is reduced, rapid expansion of gas can be prevented and gas flow loss can be reduced. Further, since the side wall of the lower portion of the auxiliary combustion chamber is enlarged and inclined toward the upper portion of the auxiliary combustion chamber, the gas flow velocity is suppressed and the mixing and combustion of the fuel and air in the auxiliary combustion chamber are suppressed.
An increase in the O _X can be prevented.

Further, since the upper end of the lower part of the auxiliary combustion chamber is expanded and the lower end thereof is contracted, unburned burnt gas in the auxiliary combustion chamber is likely to flow into the main combustion chamber and at the same time, gas flow loss is also caused. Get smaller.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the present invention will be described with reference to FIG. FIG. 1 is a sectional view of a combustion chamber of a first embodiment according to the present invention. The sub combustion chamber 2 is installed in the cylinder head 4. The auxiliary combustion chamber 2 has various shapes based on a cylindrical shape, a spherical shape, a truncated cone shape, and the like, but the auxiliary combustion chamber 2 is an example based on the cylindrical shape. A fuel injection valve 5 is installed in the sub-combustion chamber 2, and a glow plug for preheating the inside of the sub-combustion chamber 2 when the engine is started is also installed if necessary, but the glow plug is not shown.

The sub-combustion chamber 2 is connected to the main combustion chamber 1 composed of the top surface of the piston 6, the cylinder 7 and the bottom surface of the cylinder head 4 through a plurality of sub-chamber injection holes 3. The side wall of the sub-combustion chamber lower part 22 is configured to be enlarged and inclined toward the sub-combustion chamber upper part 21.

The operation of the first embodiment will be described. When the gas in the main combustion chamber 1 is compressed by the piston 6 in the compression stroke during engine operation and flows into the sub combustion chamber lower part 22 from the sub chamber injection port 3, the opening end of the sub chamber injection port of the sub combustion chamber lower part 22 is reduced. Therefore, the rapid expansion of the gas can be prevented and the gas flow loss can be reduced. The side wall of the sub combustion chamber lower part 22 is the upper side of the sub combustion chamber 2
Since expanding inclined in one direction, the gas flow rate can prevent mixing combustion is inhibited NO _X increasing of fuel and air in the auxiliary combustion chamber 2 is suppressed.

During the expansion stroke, the unburned burned gas in the sub-combustion chamber 2 expands at the upper end of the sub-combustion chamber lower part 22 and at the lower end of the sub-combustion chamber lower part 22 (near the opening end of the sub-combustion nozzle). Since the size is reduced, it easily flows into the main combustion chamber 1, and the gas flow loss at this time is also reduced. Therefore, the mixture forming combustion of the unburned fuel and the air in the main combustion chamber 1 can be promoted.

[0014]

The present invention can improve the mixture forming combustion of the fuel and air in the sub-combustion chamber, reduce the gas flow loss in the lower part of the sub-combustion chamber, promote the outflow of gas into the main combustion chamber, and thus the unburned fuel. It is possible to promote the mixture forming combustion with air. The present invention by can improve fuel economy, NO _X, the吐煙.

[Brief description of drawings]

FIG. 1 is a sectional view of a combustion chamber of a first embodiment according to the present invention.

FIG. 2 is a cross-sectional view of a combustion chamber of a conventional sub-chamber internal combustion engine.

[Explanation of symbols]

1 ... Main combustion chamber, 2 ... Sub combustion chamber, 21 ... Upper part of sub combustion chamber, 2
2 ... Lower part of auxiliary combustion chamber, 3 ... Injection port of auxiliary chamber, 4 ... Cylinder head, 6 ... Piston, 7 ... Cylinder.

Claims (1)

[Claims] 1. In a sub-chamber internal combustion engine in which the sub-combustion chamber communicates with the main combustion chamber through a plurality of sub-chamber nozzles, the side wall of the sub-combustion chamber lower part (22) is connected to the sub-combustion chamber upper part (21). A combustion chamber of a sub-chamber type internal combustion engine, characterized in that it is enlarged and inclined in a direction.