JPS58126421A - Main combustion chamber of subchamber type engine - Google Patents

Abstract

PURPOSE:To promote the mixing with air in a main combustion chamber equipped with a long and narrow state recessed part appearing in a subchamber jet, by forming an angle, produced between a side wall of the recessed part and a plane at a right angle with the center line of a piston, to 90 deg. or less. CONSTITUTION:A rectangular recess shaped with the side of a subchamber jet 7 to a semicircle is formed to the top surface of a piston 2, then the semicircle and a side wall connected to the semicircle are arranged such that an angle theta formed by the side wall of tye recess and a plane at a right angle with the center line A-A of the piston is <90 deg.. In this way, burned and unburned gases inflowing from a subcombustion chamber flow into the recess and can be prevented from an outflow to a small gap part formed between the top surface of the piston 2 and the bottom surface of a cylinder head. Accordingly, cooling and thermal loss of gas by a wall surface of the small gap part can be reduced further penetration of a jet stream can be improved then the mixing with air in a main combustion chamber, that is, the combustion can be promoted. In this way, fuel consumption, discharge of smoke and thermal loss can be decreased.

Description

[Detailed description of the invention] The present invention relates to improvements in the main combustion chamber of a subchamber engine.

Figure 1 shows the main combustion chamber of a conventional pre-chamber engine.

In the figure, the auxiliary combustion chamber 4 is recessed in the cylinder head 3. The structure of the sub-combustion chamber 4 has a hemispherical upper part.

The lower part can be truncated conical or cylindrical.
Fig. 1 shows the lower part having a truncated cone. The auxiliary combustion chamber 4 is provided with a fuel injection valve 5 and a glow plug 6 for preheating the inside of the auxiliary combustion chamber 4 when the engine is started, as necessary. The auxiliary combustion chamber 4 is connected to the top surface of the piston 2, the cylinder 8. It communicates with the main combustion chamber 1 formed from the lower surface of the cylinder head 3.

As a component of the main combustion chamber 1, the top surface of the piston 2 or the bottom surface of the cylinder head 3 has a concave portion, and FIG. 1 shows a component having a concave portion on the top surface of the piston 2.

If the angle between the recessed sidewall and a plane perpendicular to the piston center line A-A is θ, the recessed sidewall has an angle of θ≧90° (see FIG. 3). FIG. 1 shows the case where θ=90°.

During the compression stroke during engine operation, the main combustion chamber 1 is
The air inside is compressed and flows into the sub-combustion chamber 4 via the sub-chamber injection lower. The air flowing into the sub-combustion chamber 4 and the fuel injected from the fuel injection valve 5 mix.

Ignite and burn. The burnt and unburned gases in the auxiliary combustion chamber 4 are ejected into the main combustion chamber 1 through the auxiliary chamber injection lower, and at the same time work on the piston, they are mixed with the air in the main combustion chamber 1 and combusted. Close.

However, the above method has the following drawbacks.

When the burnt and unburned gas in the sub-combustion chamber 4 passes through the sub-chamber injection lower and is ejected into the main combustion chamber 1, most of it first passes through the piston 2.
It flows into the recess provided on the top surface.

At this time, the angle O between the recessed side wall and the plane perpendicular to the t-stone center line A-A is 0≧90°.

The jet flow inside the recess flows out over the side wall of the recess into a small gap formed between the top surface of the gear store 2 and the lower surface of the cylinder head 3, as shown by the hatched area in FIG. The outflowing gas (B) is cooled by the wall of the small gap, which worsens combustion and increases heat loss. In addition, the amount of gas flowing inside the recess is reduced due to the gas flowing out into the small gap, so the netration of the recess self-jet flow is reduced, and the mixing of unburned gas and air in the main combustion chamber 1 is weakened. As a result, combustion deteriorates, leading to poor smoke emissions and fuel efficiency. The above drawback is that when piston 2 is near top dead center,
This is noticeable because the gap between the top of the piston 2 and the bottom surface of the cylinder head 3 is small. Also, the above recess is located in the cylinder head 3.
The same applies to those provided on the lower surface.

The purpose of the present invention is to focus on the above points, and to solve the problem that burnt and unburned gas in the auxiliary combustion chamber 4 is removed from the top surface of the piston 2 or the cylinder head 3.
When flowing through the recess provided on the bottom surface.

The purpose of the present invention is to provide a structure that can prevent part of the gas from flowing out over the concave side wall into the small gap formed between the top surface of the piston 2 and the bottom surface of the cylinder head 3. In the main combustion chamber of a pre-chamber engine, which has an elongated concave part on the top surface of the piston or the bottom surface of the cylinder head, one end of which faces the sub-chamber nozzle, the side wall of the concave part and a plane perpendicular to the piston center line. When the angle formed by the two is θ, the angle is θ<900.

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

FIGS. 5(a), 5(b), and 5(c) show indentations in one embodiment of the present invention.

There is a recess on the top surface of the piston 2, and the shape of the piston 2 when viewed from above is a combination of a semicircle and a rectangle (the one closer to the subchamber injection lower is a semicircle), and most of the side walls of the semicircle and rectangle is the angle between the concave side wall and a plane perpendicular to the piston center MA-A. <9 o.

The case is shown below.

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

By forming the above-mentioned concave side wall, the burned and unburned gases flowing from the sub-combustion chamber 4 can flow inside the concave and can be prevented from flowing into the small gap formed between the top surface of the piston 2 and the bottom surface of the cylinder head 3. .

Therefore, it is possible to reduce gas cooling and heat loss due to the small gap wall, and also to improve the jet netration.
Mixing with the air in the main combustion chamber 1 and therefore combustion can be promoted.

For the above reasons, reductions in fuel consumption, smoke exhaust, and heat loss of the nine engines are achieved.

FIGS. 6(a), (b) and (c) show indentations of other embodiments according to the present invention.

In the above embodiment, the side wall of the half inside of the recess at the top of the piston 2 is also inclined, so that the burned and unburned gases flowing from the auxiliary combustion chamber 4 flow from the half inside over the side wall and into the small gap. (5) However, in order to facilitate the machining of the dents, the angle θ of the side wall inside the half is set to θ-90°.

In this case, it is not possible to prevent the gas from flowing out from the inside of the semicircle to the small gap, but considering that the rate of gas leakage is relatively small, it is possible to improve the machining process and the effect (except for the semicircular part, which has the same effect as the previous example). are the same) are large.

FIG. 7 is a sectional view showing a combustion chamber provided with a recess according to still another embodiment of the present invention.

There is a recess on the bottom surface of the cylinder head 3.
As shown in FIG. 8, the shape of the recess connected to the subchamber jet lower when viewed from the bottom is rectangular, with most of the side walls of the rectangle forming a plane perpendicular to the side wall and the piston center line A-A. This is a case where the angle θ<9oo is formed.

Its action and effect are the same as those of the embodiment described above.

Among the concave shapes in each of the above embodiments, if the rectangular part is made into a trapezoid (gradually decreasing in the direction of outflow from the sub-combustion chamber 4), penetration of the jet flow will be further improved and combustion in the main combustion chamber 1 will be promoted. Therefore, the effect (a) is large.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the combustion chamber of a conventional pre-chamber engine;
The figure is the ■-■ arrow view of Figure 1, and Figure 3 is the III of Figure 1.
-III arrow sectional view, FIG. 4 is an explanatory view showing a gas outflow state into a small gap portion, and FIG. 5(b) is a sectional view taken along the line 1) in FIG. 5(a), FIG. 5(c) is a sectional view taken along the line c-c in FIG. ) is a top view showing the recess on the top surface of the piston of another embodiment according to the present invention, FIG. 6(b) is a sectional view taken along the line bb in FIG. 6(a), a cross-sectional view taken along the line CC in FIG. The perspective view, FIG. 9, is a sectional view taken along the line IX-IX in FIG. 8. DESCRIPTION OF SYMBOLS 1... Main combustion chamber, 2... Piston, 3... Cylinder head, 4... Sub-combustion chamber, 7... Sub-chamber nozzle, 8...
...Simpa ° sip?
1.59; Patent Attorney Machine fBiT-BeL (7) No. 1 Kisei 9 Diagram Fang 3 Eyes 74 Diagram C3 Moan 0 Continued from page 1 0 Applicant Mitsubishi Motors Corporation 5 Shiba, Minato-ku, Tokyo
Chome 33-8

Claims (1)

[Claims] 1. In the main combustion chamber of a pre-chamber engine which has an elongated concave portion on the top surface of the piston or the bottom surface of the cylinder head, one end of which faces the pre-chamber nozzle, the side wall of the concave portion and a plane perpendicular to the piston center line. When the angle formed by is 0, θ〈90°
The main combustion chamber of a pre-chamber type engine is characterized by being formed.