JPS58569B2 - Combustion device of internal combustion engine - Google Patents

Description

[Detailed description of the invention] The present invention relates to a combustion device for an internal combustion engine.

In internal combustion engines, CO and H are mainly removed from exhaust gas purification measures.
In order to reduce the amount of unburned harmful components of C, it is known to burn a lean mixture, but combustion with such a lean mixture has poor ignitability and unstable combustion. There is a drawback.

An object of the present invention is to provide a combustion device that is improved so that stable combustion with good ignitability can be obtained even when the above-mentioned lean mixture is used.

To this end, the present invention provides an internal combustion engine having a single overhead valve type combustion chamber structure, in which a partition wall is provided inside the top wall of the combustion chamber between the intake valve and the exhaust valve so as to separate the intake valve and the exhaust valve. is divided into a main combustion chamber communicating with the intake system via the intake valve and a sub-combustion chamber communicating with the exhaust system via the exhaust valve by the partition wall, and a top surface of the piston is fitted into the sub-combustion chamber. The auxiliary piston is formed to protrude, and when the auxiliary piston fits into the auxiliary combustion chamber near top dead center, the main combustion chamber and auxiliary combustion A plurality of communication passages are opened in the partition wall to communicate the main combustion chamber and the auxiliary combustion chamber, and the communication passages are connected to the auxiliary piston at least until the piston reaches the top dead center. The central part of the partition wall and the three sides on both sides thereof in an unobstructed position and on a plane perpendicular to the piston axis direction.
The center line of the communication passage on both sides of the passage is opened at one point.

Openings are made in a V-shape on both sides of the central communication passage so that they intersect with each other at the center in the auxiliary combustion chamber, and are oriented at a predetermined angle to the combustion chamber peripheral wall in the main combustion chamber. It is characterized by the fact that

An example of related prior art in which an auxiliary combustion chamber that is highly compressed during the compression stroke is described in Japanese Utility Model Application Publication No. 49-56303; In order to prevent this, the present invention is aimed at igniting in a highly compressed auxiliary combustion chamber, causing turbulence in the air-fuel mixture in the main combustion chamber, and igniting this turbulent air-fuel mixture. The technical philosophy is completely different.

In addition, as a split combustion engine with improved ignition performance, for example, the prior art described in Japanese Patent Application Laid-open No. 136008/1987, which was previously proposed by the applicant of the present invention, is known. It is characterized in that it has a high turbulence generating effect on the air-fuel mixture in the room, and has been improved to promote combustion in the sub-combustion chamber.

An embodiment of the present invention will be described below based on the drawings.

In the figure, numeral 1 is a cylinder and 2 is a piston.

3 is a cylinder head in which a combustion chamber is formed.

A partition wall 4 is provided in the combustion chamber between the intake valve 10 and the exhaust valve 11 so as to hang down from the top wall of the combustion chamber.

It is divided into a main combustion chamber 5 which communicates with the intake system via an intake valve 10 and a sub-combustion chamber 6 which communicates with the exhaust system via an exhaust valve 11.

On the other hand, a sub-piston 7 is provided protruding from the top of the piston 2, and as is clear in FIG. Three communication passages 8 are provided that communicate the combustion chambers 5 and 6.

As shown in FIG. 1, the communication passage 8 is provided at a position where it is not blocked by the sub-piston 7 at the top dead center.

Further, the three communication passages are opened at the middle part of the partition wall 4 and on both sides thereof on a plane perpendicular to the piston axial direction.

As is clear from FIG. 2, the communication passages on both sides are arranged so that their passage center lines intersect with each other at the center on the side of the auxiliary combustion chamber 6.
On the side of the main combustion chamber 5, it is opened in a V-shape in plan with both sides l of the central communication passage so as to be oriented at a predetermined angle with respect to the peripheral wall of the combustion chamber.

The main combustion chamber 5 is provided with an ignition plug 9, and is also provided with an intake port and an intake valve 10 as described above.

On the other hand, the sub-combustion chamber 6 is provided with an exhaust port and an exhaust valve 11.

In Figure 1, reference numeral 12 is an air cleaner, and 13 is a muffler.

With the above configuration, when the piston 2 approaches the top dead center during the compression stroke, the auxiliary piston 7 fits into the auxiliary combustion chamber 6.

As a result, the compression ratio of the air-fuel mixture in the auxiliary combustion chamber 6 is increased to that of the main combustion chamber 5.
The air-fuel mixture in the auxiliary combustion chamber 6 passes through the communication passage 8 and is ejected into the main combustion chamber 5.

In this case, the communication passage 8 is provided so that the communication passages on both the left and right sides of the central communication passage inject the air-fuel mixture at an appropriate angle to the wall surface of the main combustion chamber 5. Compared to the mixture that is injected linearly, the mixture that is injected from the communication passages on both sides is injected around the peripheral wall of the combustion chamber and intersects with the mixture that is injected from the center.
The effect of generating turbulence on the air-fuel mixture in the main combustion chamber is high, and turbulence is generated in the air-fuel mixture in the main combustion chamber 5.

Therefore, the air-fuel mixture can be mixed sufficiently, and the ignitability can be improved.

After ignition, during the expansion stroke, part of the flame in the main combustion chamber is injected into the auxiliary combustion chamber through the communication passage.

In this case, prior to torch ignition from the main combustion chamber to the auxiliary combustion chamber, the communication passage is opened so that the center line of the passage intersects at the center of the auxiliary combustion chamber, so that the air-fuel mixture in the main combustion chamber is Due to the increase in expansion pressure due to ignition and combustion, the air-fuel mixture in the main combustion chamber around the partition wall is injected vigorously into the center of the auxiliary combustion chamber through the communication passages in the center and on both left and right sides before the flame is injected. death.

Since turbulence is generated in the air-fuel mixture at the center of the sub-combustion chamber, combustion in the sub-combustion chamber can be promoted.

In the exhaust stroke, the combustion gas in the main combustion chamber 5 flows into the auxiliary combustion chamber 6 through the communication passage 8, and is discharged from the exhaust valve 11 together with the combustion gas in the auxiliary combustion chamber 6.

As is clear from the above, according to the present invention, the air-fuel mixture is ejected from the auxiliary combustion chamber into the main combustion chamber near top dead center, and the turbulent flow generation effect of the air-fuel mixture in the main combustion chamber can be enhanced, so that the air-fuel mixture becomes lean. Although it is possible to improve the ignitability of the air-fuel mixture and obtain stable combustion, it also promotes combustion in the auxiliary combustion chamber and improves the exhaust gas purification effect of split combustion. It is possible to avoid a decrease in output due to

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
It is a sectional view taken along ■-■ in the figure. 1...Cylinder, 2...Piston, 3
... Cylinder head, 4 ... Bulkhead, 5
...Main combustion chamber, 6...Sub-combustion chamber, 7.
・Concave piston, 8...Communication path, 9...
- Spark plug, 10...Curved intake valve, 11...Exhaust valve, 12...Air cleaner, 13...Curved muffler.

Claims (1)

[Claims] 1. In an internal combustion engine having an overhead valve type combustion chamber structure,
A partition wall is provided inside the top wall of the combustion chamber between the two valves to separate the intake valve and the exhaust valve. The partition wall divides the chamber into a main combustion chamber that communicates with the intake system via the intake valve, and a sub-combustion chamber that communicates with the exhaust system via the exhaust valve, and a sub-piston that fits into the sub-combustion chamber on the top surface of the piston. is formed in a protruding manner, and when the auxiliary piston fits into the auxiliary combustion chamber near top dead center, the compression ratio on the auxiliary combustion chamber side is higher than the compression ratio on the main combustion chamber side having one spark plug. and an auxiliary combustion chamber, and a plurality of communication passages are opened in the partition wall to communicate the main combustion chamber and the auxiliary combustion chamber, and the communication passages are connected at least until the piston reaches the top dead center. The communicating passages on both sides are opened at three locations in the center of the partition wall and on both sides thereof on a plane perpendicular to the axial direction of the piston at a position that is not blocked by the sub-piston, and the center line of the communication passage on both sides is the same as that on the sub-combustion chamber side. Openings are formed in a V-shape on both sides of the central communication passage so that they intersect with each other in the center and are oriented at a predetermined angle to the combustion chamber peripheral wall on the main combustion chamber side. Characteristics of internal combustion engine combustion equipment.