JPS5958118A - Combustion chamber for antechamber type engine - Google Patents

Abstract

PURPOSE:To prevent the occurence of an incomplete combustion that happens when a reduction in NOx is aimed at in delaying the fuel injection timing, by tilting a part around at least the opening part of a antechamber nozzle hole of the end face at the antechamber of a partition wall. CONSTITUTION:An antechamber nozzle hole 2 pierces a partition wall between an antechamber 1 and a main chamber 3, and the antechamber 1 is of semispheric type in structure at its upper part, while a bottom surface 1a of the end face at the antechamber side of the partition wall thickens the outward side of the partition wall and tilts it in addition. When the minimum angle between an axis center line of the antechamber nozzle hole 2 and the antechamber bottom surface 1a is set down to theta2, while another minimum angle between the axis center line of the antechamber nozzle hole 2 and the main chamber side end face is set down to theta1, the angle is formed into theta2<theta1 like that. With a tilt of the antechamber bottom surface 1a, fuel injection timing is delayed to some extent from the standpoint of reducing NOx whereby even if a piston 7 ignites inside the antechamber 1 during its descendent stroke, gas flowing from the antechamber 1 to the main chamber 3 is checked so that combustion inside the antechamber 1 is accelerated and stabilized in consequence. Afterward, with a pressure rise inside the antechamber 1, gas flows into the main chamber 3 and in addition, injection velocity is speedy so that the formation of a fuel-air mixture inside the main chamber 3 and the combustion both are accelerated.

Description

[Detailed description of the invention] The present invention relates to a combustion chamber of a pre-chamber engine.

The auxiliary combustion chamber (hereinafter referred to as the auxiliary chamber) of the conventional auxiliary chamber type engine is the first
As shown in the figure. In the figure, the auxiliary chamber 1 is recessed in the cylinder head 4, and its structure has a hemispherical upper part and a truncated conical or cylindrical lower part. show something The auxiliary chamber 1 is provided with a fuel injection valve 5 and a glow plug 6 for preheating the inside of the auxiliary chamber 1 when the engine is started, as necessary. Subchamber 1, top surface of piston 70,/cylinder 8. A main combustion chamber (hereinafter referred to as the main chamber) 3 consisting of the lower surface of the nozzle 4 in the cylinder is divided by a partition wall at the bottom of the mouthpiece 9, and is communicated with it through an auxiliary chamber nozzle 2 bored in the partition wall. ing. The end face of the partition wall on the subchamber 1 side, that is, the subchamber bottom surface 9a
and the end face on the main chamber 3 side are perpendicular to the sub-chamber center line A-A, and the minimum angle between the sub-chamber bottom surface 9a and the axis of the sub-chamber nozzle 2 is θ1.
When the minimum angle between the end face of the main chamber and the axis of the sub-chamber nozzle 2 is θ, then θ1-θ2.

During the compression stroke during engine operation, air in the main chamber 3 is compressed by the piston 7 and flows into the subchamber 1 through the subchamber nozzle 2 to generate a vortex S. Air flowing into the auxiliary chamber 1 and the fuel injection valve 5
Mixing with the fuel injected from the fuel is promoted by this vortex, and ignition occurs and combustion occurs.

Burned and unburned gas in the subchamber J passes through the subchamber nozzle 2.

It is ejected into the main chamber 3, works on the piston, and simultaneously mixes with the air in the main chamber 3 and causes combustion.

However, the above method has the following drawbacks.

If the fuel injection timing is delayed in order to reduce NOx in the sliding gas, the piston 7 will be on its downward stroke when the fuel spray starts to ignite and burn in the subchamber 1, so the gas in the subchamber 1 will be Because it flows out into the main chamber 3 through the chamber nozzle 2, the auxiliary chamber 1
The fuel inside flows out into the main chamber 3 with a large amount of unburned fuel. In this case, when the load is low, that is, the fuel injection amount is low, in the main chamber 3 there is too much air and the temperature level of the ejected gas is low, so incomplete combustion occurs in the main chamber 3 as well.

Emissions of unburned hydrocarbons, HC, etc. will increase. Furthermore, if the engine is in a high load operation range, that is, a large amount of fuel injection, there will be a lack of air in the main chamber 3, causing incomplete combustion and worsening smoke emissions.

In order to suppress the outflow of gas from the sub-chamber 1 to the main chamber 3 during the period of backfire in the sub-chamber 1, when the sub-chamber nozzle angle 02 (-θ1) is reduced, the sub-chamber nozzle 2 moves towards the sub-chamber nozzle 9. Otherwise, the swirling radius r8 of the vortex flow inside the auxiliary chamber 1 cannot be secured. The former protrusion of the sub-chamber nozzle 2 occurs when the vortex swirl radius r8 is secured, and is not permissible due to the cylinder head structure.

The latter occurs when the position of the pre-chamber nozzle 2 is moved away from the cylinder centerline B-B to cover the former drawback, and the vortex swirl radius r becomes excessive, making it difficult to obtain a good vortex flow in the pre-chamber 1. combustion will worsen.

An object of the present invention is to focus on the above-mentioned points and provide a combustion chamber that can prevent incomplete combustion that occurs when NOx reduction is attempted by delaying the fuel injection timing.

The feature is that in a sub-chamber type internal combustion engine having a sub-chamber nozzle that is bored in a partition wall that partitions the main chamber and sub-chamber and communicates the main chamber and sub-chamber, the axis of the sub-chamber nozzle is The minimum angle between the line and the end surface of the partition wall on the subchamber side is represented by 02,
When the minimum angle between the axis of the subchamber nozzle and the main chamber side end surface of the partition wall is θl, at least a portion of the subchamber side end surface of the partition wall around the opening of the subchamber nozzle is inclined. Therefore, θ2<θ1.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view showing the subchamber of the first embodiment of the present invention.

In the figure, 1 is an auxiliary chamber, 2 is an auxiliary chamber nozzle, 3 is a main chamber, 4 is a cylinder head, 5 is a fuel injection valve, 6 is a glow plug, 7 is a piston, and 8 is a cylinder.

The auxiliary chamber nozzle 2 passes through the partition between the auxiliary chamber 1 and the main chamber 3 and communicates with the compartment 1.3.

The sub-chamber (2) has a hemispherical upper structure, and the sub-chamber bottom surface 1a, which is the end surface of the partition wall on the sub-chamber side, is made thicker on the outer side of the partition wall and inclined as a whole, as shown in the figure.

That is, the minimum angle between the axial line of the sub-chamber nozzle 2 and the sub-chamber bottom surface 1a is set to 02, and the angle of the sub-chamber nozzle 2 is calculated as follows. If the minimum angle between the first conductor and the main chamber side end surface of the second partition wall is 01, then the angle is θ2 by θi due to the above-mentioned inclination.

The functions and effects of the above configuration will be described.

When the sub-chamber bottom surface 1a is inclined as shown in the figure.

This is because, in order to reduce NOx, even if the fuel injection timing is delayed and ignition occurs in the subchamber 1 when the piston 7 is on its downward stroke, the outflow of gas from the subchamber 1 to the main chamber 3 is suppressed.

Combustion within the pre-chamber 1 is promoted and becomes stable.

Thereafter, due to the pressure increase in the sub chamber 1, the gas flows out into the main chamber 3, and at this time, the ejection speed is high.

Air-fuel mixture formation and combustion within the main chamber 3 are promoted.

In the case of the present invention as described above, there are two NOx engines.

It is possible to reduce HC and smoke emissions, and also to reduce noise.

FIG. 3 is a sectional view showing the subchamber of another embodiment of the present invention.

A part of the bottom surface of the sub-chamber 1, that is, a portion 1b around the opening of the sub-chamber nozzle 2, is tilted to an angle of θ2 θ! The operation and effect are the same as in the embodiment described above.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the subchamber of a conventional subchamber type engine. FIG. 2 is a sectional view showing the subchamber of one embodiment of the present invention, and FIG. 3 is a sectional view of the subchamber of another embodiment of the invention. ■...Subchamber, 2...Subchamber nozzle, 3...Main chamber + 1
819 B... Bottom of the sub-chamber, 1b... Part of the bottom of the sub-chamber. Rice 1 diagram

Claims (1)

[Claims] (2) In a sub-chamber type internal combustion engine having a sub-chamber nozzle that is bored in a partition wall that partitions the main chamber and the sub-chamber and communicates the main chamber and the sub-chamber, the axial line of the sub-chamber nozzle and the When the minimum angle between the sub-chamber side end face and the sub-chamber side end face is represented by θ2, and the minimum angle between the axial line of the sub-chamber nozzle and the main chamber-side end face of the partition wall is θ1, at least the sub-chamber side end face of the partition wall A combustion chamber for a pre-chamber type engine, characterized in that a portion around the opening of the pre-chamber nozzle is tilted so that the angle is θ2 - θ1.