JPH0220423Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> The purpose of this invention is to prevent spark plug misfires and improve combustion performance regarding the combustion chamber with pre-chamber of a spark-ignition four-stroke engine. .

To explain in more detail the application field of the technology that is the premise of the present invention, for example, as shown in FIG. 1 or FIG. The main combustion chamber 3 is recessed, and one end portion 6 of the inner surface 5 of the cylinder head 4
An auxiliary combustion chamber 7 is recessed in the main combustion chamber 3 and an auxiliary combustion chamber 7.
A communication chamber 8 is formed in communication with a part of the peripheral wall 9 of the main combustion chamber 3 at a position facing the sub-combustion chamber 7 to allow smooth gas flow between the sub-combustion chamber 7 and the ignition plug 10. The present invention relates to a combustion chamber with an auxiliary chamber for a spark-ignition four-cycle engine.

<Prior Art> In this type of conventional technology, as shown in FIG. 5, the terminal wall surface 11 of the communication chamber 8 is formed vertically,
By configuring the virtual extension surface 12 of the vertical end wall surface 11 to match the end wall surface 14 of the sub-combustion chamber 7, a strong swirl can be generated in the sub-combustion chamber 7 during the compression process. There is.

<Problems to be solved by the invention> However, in the above configuration, ignition is performed in the auxiliary combustion chamber where a strong swirl is generated.
This powerful swirl could blow out the spark or prevent the formation of a flame kernel, often causing misfires.

This also means that as the engine speeds up,
As the swirl becomes more powerful, it means that the tendency for the spark to be blown out increases more and more, especially in high-speed engines whose use is increasing these days. has become an urgent matter.

<Means for solving the problems> The present invention solves the above problems,
This was proposed with the aim of preventing misfires and smoothly swirling sparks to improve combustion performance. When the position B near the combustion start position A just before the top dead center is reached, the virtual extension surface 12 of the upwardly expanding inclined end wall surface 11 of the communication chamber 8 reaches the lower edge of the opening of the end wall surface 14 of the sub-combustion chamber 7. 1
5, the upper end edge 16 of the inclined end wall surface 11 of the communication chamber 8 is moved by a slight dimension toward the main combustion chamber 3 side than the opening lower end edge 15 of the end end wall surface 11 of the auxiliary combustion chamber 7. (The reference numerals are used in FIGS. 1 to 3 as reference examples.)

<Operations and Effects of the Invention> In the present invention, when the piston reaches the combustion start position before top dead center, the imaginary extension surface of the upwardly expanding and inclined terminal side wall of the communication chamber becomes the secondary Since the air-fuel mixture is shifted appropriately from the lower edge of the opening on the final wall surface of the combustion chamber, part of the air-fuel mixture guided by the main combustion chamber collides with the lower edge near the opening of the auxiliary combustion chamber, and this lower edge is, so to speak, a part of the air-fuel mixture. acts as a resistance to flow into the auxiliary combustion chamber.

Therefore, in the sub-combustion chamber, the swirl does not become stronger than a predetermined value, and the spark caused by ignition is not blown out by the swirl, allowing the flame kernel to grow smoothly.

Further, in the present invention, a small turbulence of the air-fuel mixture is actively generated throughout the combustion chamber during the swirl during a period before combustion spreads.

Moreover, at the combustion timing when combustion spreads, that is, at the moment when the piston rises to a position close to beyond the combustion start position just before top dead center, the virtual extension surface of the upwardly expanding and inclined end side wall surface of the communication chamber is Since it matches the lower edge of the opening on the final side wall of the combustion chamber, it is possible to guide the mixture into the auxiliary combustion chamber all at once and generate a strong swirl, thereby eliminating small turbulence in the mixture before the combustion process. By promoting the combustion gas and making it uniform throughout the entire area, flame propagation can be quickly achieved and combustion performance can be improved.

In other words, the present invention is capable of suppressing the generation of swirl to some extent during ignition to prevent misfires, while generating a strong swirl during the combustion process after ignition, and is compatible with the recent trend of increasing engine speed. In addition to meeting these requirements, the combustion performance of the engine can be significantly improved by eliminating the risk of misfire.

Moreover, the present invention has a simple structure in which the communication chamber connected to the main combustion chamber is formed into a shape that satisfies predetermined conditions in relation to the auxiliary combustion chamber.
In addition to being inexpensive to implement, it can also be easily applied to existing spark-ignition four-stroke engines by simply adding simple processing to the piston head.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. Figure 1 is a longitudinal sectional front view showing the combustion process around the combustion chamber of a spark-ignition four-stroke engine;
The figure is a diagram equivalent to Figure 1, also showing the ignition time, and Figure 3 is a schematic plan view showing the relationship between the piston head and the auxiliary combustion chamber, forming the central cylinder 20 of the four-stroke engine E, and showing the crankshaft. A piston 21 interlocked with is fitted into the cylinder 20 so as to be vertically slidable.

Further, the cylinder head 4 is mounted above the cylinder block 22, and the cylinder head 4 has intake/exhaust ports 23, 24 facing the cylinder 20, and intake/exhaust valves 25, 26 can be opened and closed at the ends of the ports. Install.

Furthermore, an auxiliary combustion chamber 7 is recessed in one end 6 of the inner surface 5 of the cylinder head 4 so as to face the cylinder 20, and an ignition plug 10 is screwed onto the upper end 7a of the inner wall of the auxiliary combustion chamber 7. The entire inner wall of the inner wall 7 is formed in a curved shape so as to easily generate a swirl, and in particular, the left end wall surface 14 is provided in an upwardly expanding inclined shape.

On the other hand, a main combustion chamber 3 is recessed in the central part 2 of the piston head 1, and a communication chamber 8 is communicated with a part of the peripheral wall 9 of the main combustion chamber 3 at a position opposite to the auxiliary combustion chamber 7, so that the main combustion chamber Gas flows smoothly between the combustion chamber 3 and the sub-combustion chamber 7.

The communication chamber 8 has a left end wall surface 11 that is upwardly expanded and sloped, and when the piston 21 rises to a combustion process position after ignition, that is, a position B in the vicinity of the combustion start position A, Left end wall surface 11
The upper edge 16 is configured to be deviated to the right by a slight dimension toward the main combustion chamber 3 than the lower edge 15 of the opening of the left end wall surface 11 of the auxiliary combustion chamber 7 (see FIG. 1).

Therefore, in this case, the piston 21 is at the ignition position,
That is, when rising to the combustion start position A, the upwardly expanding inclined side wall surface 11 of the communication chamber 8 has its virtual extension surface 12 biased to the left side of the lower opening edge 15 of the left end wall surface 14 of the sub-combustion chamber 7. On the other hand, when the piston 21 further rises to the combustion process position B, the virtual extension surface 12 coincides with the lower edge 15 of the opening of the auxiliary combustion chamber 7.

Therefore, at the time of ignition, the inner surface 5 of the cylinder head near the lower edge 15 of the opening of the auxiliary combustion chamber 7 acts as a resistance, and the air-fuel mixture directed by the upwardly expanding inclined side wall surface 11 of the main combustion chamber 3 flows into the auxiliary combustion chamber 7. They are prevented from entering all at once, and the powerful generation of swirls is suppressed.

In addition, during the combustion process in which combustion spreads after ignition, the air-fuel mixture directed in the main combustion chamber 3 smoothly enters the auxiliary combustion chamber 7 and can generate a strong swirl, causing the air-fuel mixture to uniformizes and accelerates small disturbances in the flame, increasing the flame propagation speed,
Combustion performance can be improved.

FIG. 5 shows a second embodiment of the present invention.
The left end wall surface 14 of the auxiliary combustion chamber 7 is raised substantially vertically, and the communication chamber 8 is raised during combustion after ignition.
The imaginary extension surface 12 of the upwardly expanding inclined side wall surface 11 coincides with the lower edge 15 of the opening of the auxiliary combustion chamber 7.

Therefore, in the second embodiment, it is not necessary to finish the entire inner wall of the auxiliary combustion chamber 7 into a curved shape, and the machining work can be simplified, and the air-fuel mixture oriented in the main combustion chamber 3 is used for auxiliary combustion. Since the direction is slightly corrected by the perpendicular wall 14 of the chamber 7, the swirl strength at the time of ignition can be better suppressed, and the risk of misfire can be smoothly eliminated.

The present invention adjusts the intensity of the swirl in the sub-combustion chamber, so it can be applied to any spark ignition four-cycle engine, regardless of whether it is a gasoline engine or a gas engine.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is a longitudinal sectional front view showing the combustion process around the combustion chamber of a spark-ignition four-cycle engine, and FIG.
3 is a schematic plan view showing the relationship between the piston head and the auxiliary combustion chamber, FIG. 4 is a view equivalent to FIG. 1 showing the second embodiment, and FIG. FIG. 5 is a diagram corresponding to FIG. 1 showing a conventional example. 1... Piston head, 2... Near the center of 1, 3... Main combustion chamber, 4... Cylinder head, 5
...Inner surface of 4, 6...One end of 5, 7... Sub-combustion chamber, 8... Communication chamber, 9... Peripheral wall of 3, 10...
Spark plug, terminal wall surface of 11...8, virtual extension surface of 12...11, terminal wall surface of 14...7, 15...1
4, the lower edge of the opening, and the upper edge of 16...11.

Claims (1)

[Scope of utility model registration request] A main combustion chamber 3 is recessed in the vicinity of the center 2 of the piston head 1 of the spark-ignition four-cycle engine E, and a sub-combustion chamber 7 is recessed in the inner surface 5 of the cylinder head 4 near one end 6. 3 and the auxiliary combustion chamber 7 is formed by communicating with a part of the peripheral wall 9 of the main combustion chamber 3 at a position facing the auxiliary combustion chamber 7. Spark plug 10 in chamber 7
In the combustion chamber with a pre-chamber of a spark-ignition four-cycle engine, the terminal wall surface 11 of the communication chamber 8
is formed into an upwardly expanding inclined surface, and when the piston head 1 reaches a position B in the vicinity of the combustion start position A immediately before the top dead center, a virtual extension of the upwardly expanding inclined end side wall surface 11 of the communication chamber 8 is formed. Surface 12 is the final wall surface 1 of the sub-combustion chamber 7
The upper end edge 16 of the inclined end wall surface 11 of the communication chamber 8 is aligned with the lower end edge 15 of the opening of the communication chamber 8.
A combustion chamber with an auxiliary chamber of a spark-ignition four-cycle engine, characterized in that the auxiliary combustion chamber 7 has a slightly deviated dimension toward the main combustion chamber 3 side with respect to the opening lower edge 15 of the terminal side wall surface 14 of the auxiliary combustion chamber 7. .