JPH0216033Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> The present invention relates to the structure of a combustion chamber of a spark-ignition engine, and particularly relates to a combustion chamber of an engine in which a dome-shaped auxiliary combustion chamber is formed in the cylinder head. .

<Prior art> In order to suppress the generation of nitrogen oxides and carbon monoxide in a spark-ignition engine, a dome-shaped sub-combustion chamber is formed in the cylinder head, and an ignition plug is placed in this sub-combustion chamber. It is known that the auxiliary combustion chamber opens into the cylinder chamber (main combustion chamber) and the air-fuel mixture is made turbulent during the compression stroke and pushed into the dome-shaped auxiliary combustion chamber (Japanese Patent Publication No. 51-38001
Publication No.).

<Problems to be solved by the invention> However, in engines with this type of dome-shaped sub-combustion chamber, the upper surface of the piston is formed in a flat shape, so that the mixture flowing into the dome-shaped sub-combustion chamber during the compression stroke is The problem is that the airflow becomes a large vortex, making it impossible to sufficiently increase the mixing ratio of fuel and air.

On the other hand, in a diesel engine having a spiral combustion chamber, a dome-shaped recess for forming a spiral chamber is formed in the cylinder head, and a sub-chamber mouthpiece is fitted into the entrance of this dome-shaped recess to reduce the swirl. By omitting the auxiliary chamber cap and using the dome-shaped recess as the dome-shaped auxiliary combustion chamber, the cylinder head of the spark ignition engine can be made into a common part with the cylinder head of the diesel engine mentioned above. In some cases, manufacturers are trying to increase mass productivity and reduce manufacturing costs.

However, in such a case, the location, shape, size, etc. of the dome-shaped secondary combustion chamber of the spark ignition engine are restricted in order to make it common with the spiral chamber of the diesel engine. Therefore, there is a problem that the conditions for mixing fuel and air deteriorate, and the mixing ratio further deteriorates.

<Means for solving the problems> The present invention is intended to increase the mixing ratio of fuel and air in an engine having a dome-shaped auxiliary combustion chamber formed in the cylinder head. The main combustion chamber is recessed in the central part of the head, and a communication groove is formed in the part of the wall surrounding the main combustion chamber that faces the dome-shaped sub-combustion chamber, and the bottom of the communication groove is connected to the main combustion chamber. It is characterized by being positioned higher than the bottom of the chamber in a stepped manner.

<Function> In this invention, the main combustion chamber is recessed in the piston head, and a communication groove is formed in the part of the wall surrounding the main combustion chamber that faces the sub-combustion chamber, and the bottom of the communication groove is used as the main combustion chamber. Since the chamber is formed in a stepped manner higher than the bottom of the chamber, during the compression process, the air-fuel mixture flows centripetally from inside the cylinder into the main combustion chamber near the center of the piston head, passes through the communication groove, and undergoes secondary combustion. pushed into the room.

At this time, the air-fuel mixture is accelerated before and after passing through the communication groove and bends three times in a step-like manner.
A large amount of fine vortices are generated in the flow. As a result, the air-fuel mixture is vigorously stirred and mixed while being forced into the sub-combustion chamber.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.

Main Embodiment (See FIGS. 1 to 3) FIG. 1 is a longitudinal sectional front view of the vicinity of a combustion chamber of a spark-ignition four-stroke engine, and FIG. 2 is a sectional view taken along the line taken in FIG. 1. In the figure, 1 is a piston, 2 is a cylinder block, 3 is a cylinder liner, and 4 is a cylinder head.

The intake/exhaust ports 5, 6 formed in the cylinder head 4 face the inside of the cylinder 7, and the intake/exhaust ports 5, 6 formed in the cylinder head 4 are placed at the ends thereof.
Exhaust valves 8 and 9 are installed. Further, an auxiliary combustion chamber 10 is recessed in a dome shape near one end of the inner surface of the cylinder head 4 and faces into the cylinder 7.
An ignition plug 11 is screwed onto the upper end of the inner wall of 0.

The present invention is characterized in that, in an engine having such a structure, the combustion chamber has a structure as described below.

That is, the main combustion chamber 13 is recessed in a central portion of the head portion 12 of the piston 1, and a communication groove 15 is formed in the peripheral wall 14 of the recessed main combustion chamber 13 so as to face the sub-combustion chamber 10. It has been done.

The dome-shaped auxiliary combustion chamber 10 stands upright substantially parallel to the cylinder 7, and a portion thereof overhangs the inner peripheral surface of the cylinder 7 in plan view. The combustion chamber 13 is located eccentrically toward the dome-shaped auxiliary combustion chamber 10 with respect to the piston head 12.

As shown in FIG. 2, this communication groove 15 is formed parallel to a line connecting the piston axis P and the auxiliary combustion chamber 10 in plan view, and its width is equal to the diameter of the opening of the auxiliary combustion chamber 10 into the cylinder 7. slightly larger than, and
Its depth is made shallower than the recess depth of the main combustion chamber 13, so that the groove bottom 16 of the communication groove 15 is higher than the chamber bottom 17 of the main combustion chamber 10 in a stepped manner.

Another Embodiment (See FIGS. 3 to 6) FIGS. 3 and 4 show another embodiment in which the arrangement of the auxiliary combustion chamber 10 is changed. In what is shown in FIG. 3, the auxiliary combustion chamber 10 is formed so as to be inscribed in the cylinder liner inner circumferential surface 18 in plan view. In the case shown in FIG. 4, the auxiliary combustion chamber 10 is formed in an inclined shape so that the inlet side of the sub-combustion chamber 10 approaches the center of the cylinder 7.

5 and 6 show modified examples of the communication groove 15. FIG. In the one shown in FIG. 5, one side wall 19 of the communication groove 15 is formed into a parallel groove that tangentially connects the inner circumferential surface of the main combustion chamber 13 and the inner circumferential surface of the auxiliary combustion chamber 10. . What is shown in FIG. 6 is the communication groove 15.
is formed in a groove that tapers toward the outside of the cylinder.

<Effects of the invention> In the present invention, in the combustion chamber of a spark ignition engine in which a dome-shaped auxiliary combustion chamber is formed in the cylinder head, the main combustion chamber is recessed near the center of the piston head, and the main combustion chamber is recessed. A communication hole is formed in a portion of the surrounding wall facing the dome-shaped sub-combustion chamber, the groove bottom of which is positioned higher than the bottom of the main combustion chamber in a stepped manner. Therefore, during the compression stroke, the air-fuel mixture sucked into the cylinder flows centripetally from inside the cylinder into the main combustion chamber near the center of the piston head, and when it flows into the auxiliary combustion chamber through the communication groove, it accelerates. As it bends three times in a step-like manner, a large amount of fine vortices are generated in the flow, which improves the agitation and mixing of the air and fuel in the air-fuel mixture.
In addition to improving mixing performance, flame propagation speed also increases,
Combustion performance can be improved. This not only improves the fuel efficiency of the engine, but also increases the engine output.

Furthermore, it is possible to actively generate small turbulence in the air-fuel mixture throughout the combustion chamber during the swirl.
It is possible to use a lean mixture, completely burn the mixture, and prevent the generation of harmful exhaust gas components.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a longitudinal sectional front view of the vicinity of the combustion chamber of a spark-ignition four-cycle engine, Fig. 2 is a sectional view taken along the line shown in Fig. 1, and Figs. 3 and 4 are separate views. FIG. 1 is a view corresponding to the embodiment, and FIGS. 5 and 6 are views corresponding to FIG. 2 showing modified examples of the communication groove. 4...Cylinder head, 7...Cylinder, 10
... Sub-combustion chamber, 11 ... Spark plug, 12 ... Piston head, 13 ... Main combustion chamber, 15 ... Communication groove,
16... Groove bottom of the communication groove, 17... Chamber bottom of the main combustion chamber.

Claims (1)

[Scope of claims for utility model registration] 1. Main combustion chamber 13 in cylinder 7 of a spark ignition engine
An engine with a dome-shaped sub-combustion chamber of a spark ignition engine configured by communicating a dome-shaped sub-combustion chamber 10 recessed with the cylinder head 4 in a part near the periphery of the engine, and providing a spark plug 11 in the dome-shaped sub-combustion chamber 10. It's hot,
The main combustion chamber 1 is located near the center of the piston head 12.
3 is recessed, and among the peripheral walls of the main combustion chamber 13,
A communication groove 15 is formed in the wall portion facing the dome-shaped auxiliary combustion chamber 10, and the groove bottom 16 of the communication groove 15 is positioned higher than the chamber bottom 17 of the main combustion chamber 13 in a stepped manner. A combustion chamber with a dome-shaped subchamber for a spark ignition engine. 2. Combustion of a spark ignition engine with a dome-shaped sub-combustion chamber as set forth in claim 1, in which a part of the dome-shaped sub-combustion chamber 10 overhangs the inner circumferential surface of the cylinder 7 to the outside in plan view. Room. 3. A spark ignition engine with a dome-shaped auxiliary chamber as set forth in claim 1 of the utility model registration claim, in which the inner circumferential surface of the inlet of the dome-shaped auxiliary combustion chamber 10 is substantially inscribed in the inner circumferential surface of the cylinder in plan view. combustion chamber. 4. A combustion chamber with a dome-shaped sub-combustion chamber for a spark ignition engine according to claim 1, in which the dome-shaped sub-combustion chamber 10 stands upright substantially parallel to the cylinder 7. 5. A combustion chamber with a dome-shaped auxiliary chamber for a spark ignition engine as set forth in claim 3 of the utility model registration, in which the dome-shaped auxiliary combustion chamber 10 is inclined toward the cylinder 7 as the inlet side approaches the cylinder 7. 6. The combustion chamber with a dome-shaped auxiliary chamber for a spark ignition engine as set forth in claim 1 of the utility model registration claim, in which the communication groove 15 is formed in a tapered shape in plan view. 7. A combustion chamber with a dome-shaped auxiliary chamber for a spark ignition engine as set forth in claim 1 of the utility model registration claim, in which the communication groove 15 is oriented in a radial direction with respect to the main combustion chamber 13. 8. A combustion chamber with a dome-shaped auxiliary chamber for a spark ignition engine according to claim 1, in which the communication groove 15 is oriented tangentially to the main combustion chamber 13. 9 The main combustion chamber 13 is connected to the piston head 12,
A combustion chamber with a dome-shaped auxiliary chamber for a spark ignition engine as set forth in claim 1 of the utility model registration claim, which is located eccentrically on the dome-shaped auxiliary combustion chamber 10 side.