JP3212457B2 - Combustion chamber of subchamber internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion chamber of a sub-chamber internal combustion engine.

[0002]

2. Description of the Related Art A combustion chamber of a conventional sub-chamber internal combustion engine is shown in FIGS.
7 will be described. 5 is a sectional view of a combustion chamber of a conventional sub-chamber internal combustion engine, FIG. 6 is a top view of a conventional piston, and FIG. 7 is a sectional view taken along line VII-VII of FIG. In the figure, reference numeral 1 denotes a main combustion chamber, which is a space surrounded by the upper surface of the piston 7, the cylinder 8, and the lower surface of the cylinder head 4. Reference numeral 2 denotes a sub-combustion chamber, which is recessed in the cylinder head 4 at a distance from the cylinder center line A-A and communicates with the main combustion chamber 1 via a sub-chamber injection hole 3 opened in a sub-chamber base 9. The shape of the sub-combustion chamber 2 is hemispherical at the top and frusto-conical at the bottom, with a fuel injection valve 5 installed at the top, and a glow plug 6 for preheating the inside of the sub-combustion chamber 2 when the engine is started. . A piston cavity is provided on an upper surface of a piston 7 which is a lower surface of the main combustion chamber 1. The shape of the piston cavity is formed deepest near the outlet of the sub-chamber injection port 3 and gradually becomes shallower toward the center of the cylinder, and eventually coincides with the piston top surface 10 and its width is constant.

The operation of the conventional example will be described. During operation of the engine, in the compression stroke, the air in the main combustion chamber 1 is compressed by the piston 7, flows into the sub-combustion chamber 2 through the sub-chamber injection port 3, and generates a vortex 5. The velocity of the vortex 5 increases as the piston 7 approaches the top dead center. When fuel is injected from the fuel injection valve 5 in the direction of the swirl 5, the fuel forms an air-fuel mixture while swirling in the sub-chamber 2 together with the swirl 5 and starts igniting from the vicinity of the glow plug 6. Burn. The combustion gas and unburned gas in the sub-combustion chamber 2 pass through the sub-chamber injection port 3 due to the pressure difference between the main combustion chamber 1 and the sub-combustion chamber (main combustion chamber pressure <sub-combustion chamber pressure) and the downward movement of the piston. Combustion chamber 1
Squirt to The ejected gas works on the piston 7 and at the same time mixes with the air in the main combustion chamber 1 to further diffuse combustion.

[0004]

In the sub-chamber internal combustion engine, the performance of the sub-chamber internal combustion engine is usually increased while reducing the throttling loss or heat loss of the sub-chamber to reduce the unburned exhaust gas. However, if the sub chamber injection port is too wide, the energy of the jet flow from the sub combustion chamber to the main combustion chamber during the expansion stroke tends to decrease, and the mixture in the main combustion chamber is insufficiently formed, so that the combustion becomes slow and the performance deteriorates.

[0005] It is an object of the present invention to promote the mixing of unburned burned gas spouted from the sub chamber injection port into the main combustion chamber at high speed and fresh air in the main combustion chamber, and to reduce the air utilization rate of the entire main combustion chamber. An object of the present invention is to provide a combustion chamber of a sub-chamber internal combustion engine in which the combustion period is shortened, the isovolume combustion efficiency is improved, and the medium and late diffusion combustion is promoted.

[0006]

According to the present invention, in the combustion chamber of a sub-chamber internal combustion engine, the shape of the piston cavity of the main combustion chamber is made shallow from near the sub chamber injection port outlet toward the cylinder center. It becomes, and both of the side walls of the width is moderately narrows it earlier than toward the cylinder center from the auxiliary chamber injection port exit vicinity sediment expanding moderately Conversely, and is becoming narrow least width of said piston cavity section
Bottom side the piston cavity is characterized by being configured to be tilted to the direction in which Hiroshiku.

[0007]

The unburned and burned gas ejected from the sub chamber injection port into the main combustion chamber travels mainly through the center of the cylinder in the piston cavity toward the cylinder wall. Penetration gradually decreases as it progresses while spreading to the surrounding area. Since the side wall of the piston cavity is inclined inward and the width of the piston cavity is narrowed, diffusion to the surroundings is reduced, and reduction in penetration is reduced. Mixing with air is promoted.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the present invention will be described with reference to FIGS. FIG. 5 is a sectional view of a combustion chamber of a sub-chamber internal combustion engine according to a first embodiment of the present invention, FIG. 1 is a top view of a piston according to the first embodiment of the present invention, and FIG. Sectional view, FIG. 3
1 is a sectional view taken along line III-III of FIG. 1, and FIG. 4 is a sectional view taken along line IV-IV of FIG. In the drawing, the parts other than the piston are the same as the conventional one. 1 is a main combustion chamber, an upper surface of a cylinder 8 and a piston 7,
This is a space surrounded by the lower surface of the cylinder head 4. Reference numeral 2 denotes a sub-combustion chamber, which is recessed in the cylinder head 4 and has a hemispherical upper part and a truncated conical lower part, and is communicated with the main combustion chamber 1 by a sub-chamber injection port 3. Reference numeral 9 denotes a sub-chamber base, which forms the lower part of the sub-combustion chamber 2 and is provided with a sub-chamber injection port 3. Reference numeral 5 denotes a combustion injection valve, and reference numeral 6 denotes a glow plug, all provided in the sub-combustion chamber 2.

A piston cavity is provided on the upper surface of the piston 7 and has a wedge shape with a depth that is deepest and shallow toward the center of the cylinder below the sub chamber injection port 3. The width of the piston cavity is adjusted in the direction of travel of the gas injected into the main combustion chamber 1 by the cylinder center line A-.
It gradually narrows to around A, and then gradually expands. Further, the side wall of the piston cavity is perpendicular to the piston top surface 10 (θ = 0) in the vicinity of the opening of the sub-chamber injection port. θ ≦ 60
°.

The operation of the first embodiment will be described. In the compression stroke during operation of the engine, the compressed air flows from the main combustion chamber 1 through the sub chamber injection port 3 into the sub combustion chamber 2 to generate a vortex 5.
Fuel is injected from the fuel injection valve 5 along the flow direction of the vortex S, and the fuel is ignited near the glow plug 6.

Burned gas and unburned gas ignited and burned in the sub-combustion chamber 2 are spouted into the main combustion chamber 1 at high speed through the sub-chamber injection port 3. The jet gas collides with the deepest part of the piston cavity, travels along the bottom surface of the piston cavity, through a very small gap surrounded by the lower surface of the cylinder head 4 and the top surface 10 of the piston, and reaches the wall surface of the cylinder 8. At the same time, diffusion combustion is performed while mixing with air in the main combustion chamber 1, and the pressure pushes down the piston 7 to perform work.

However, in order to improve the performance by reducing the throttle loss of the sub chamber injection port, the sub chamber injection port 3 is expanded to some extent. For this reason, the penetration force of the gas injected at high speed through the sub chamber injection port 3 to the main combustion chamber 1 is also considerably reduced from the cylinder center line AA to the cylinder 8 wall. Therefore, the width of the piston cavity is gently reduced and then expanded in the traveling direction of the gas ejected at a high speed, and the side wall angle θ of the piston cavity is inclined inward with respect to the traveling direction of the gas within the range of 0 <θ ≦ 60 °. Thus, the jet gas is prevented from protruding out of the piston cavity and is restrained.

By restricting the flow of the jet gas, the dispersion of the jet gas from the vicinity of the cylinder center to the wall of the cylinder 8 and a decrease in penetration are suppressed. This effect is particularly large when the piston 7 is at the top dead center. As described above, the gas ejected into the main combustion chamber 1 travels while decreasing the kinetic energy and the penetration force, so that the main combustion chamber 1 including the air introduction around the piston cavity and the air on the peripheral wall of the cylinder 8 is included.
The air-fuel mixture in the inside becomes active, and the air utilization rate of the entire main combustion chamber 1 is improved. In addition, it is necessary to set the degree of reduction of the piston cavity width to an appropriate degree which does not impair the performance.

[0014]

According to the present invention, mixing of unburned and burned gas spouted from the sub chamber injection port into the main combustion chamber at high speed and fresh air in the main combustion chamber is achieved at an early stage, and the air utilization rate of the main combustion chamber is improved. I do. Therefore, the combustion period is shortened, the isovolume combustion efficiency is improved, and the later-stage diffusion combustion in the main combustion chamber is promoted. In other words, the startability and output of the engine are improved, and the emission of smoke, unburned hydrocarbons and the like can be reduced.

[Brief description of the drawings]

FIG. 1 is a top view of a piston according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG. 1;

FIG. 4 is a sectional view taken along line IV-IV in FIG. 1;

FIG. 5 is a cross-sectional view of a combustion chamber of a sub-chamber internal combustion engine according to a first embodiment of the present invention and a conventional example.

FIG. 6 is a top view of a conventional piston.

FIG. 7 is a sectional view taken along the line VII-VII in FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main combustion chamber, 2 ... Sub combustion chamber, 3 ... Sub chamber injection port, 4 ... Cylinder head, 5 ... Fuel injection valve, 6 ... Glow plug, 7 ...
Piston, 8: Cylinder, 9: Sub chamber base, 10: Piston top surface, AA: Cylinder center line, θ: Side wall angle of piston cavity.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-58-126421 (JP, A) JP-A-6-336928 (JP, A) JP-A-6-159134 (JP, A) 118220 (JP, A) JP-A-6-264744 (JP, A) JP-A 54-178806 (JP, U) JP-A 62-18329 (JP, U) Patent 3080816 (JP, B2) (58) Field (Int.Cl. ⁷ , DB name) F02B 19/00-19/18

Claims (1)

(57) [Claims] In a combustion chamber of a sub-chamber internal combustion engine, the shape of a piston cavity of a main combustion chamber becomes shallower from a vicinity of an outlet of a sub-chamber toward a center of a cylinder from an outlet of a sub-chamber.
And moderately narrows it earlier than its width is toward the cylinder center from the auxiliary chamber injection port exit vicinity sediment expanding moderately Conversely, and said both side walls of at least the piston cavity width is becoming narrower interval piston combustion chamber of the subchamber type internal combustion engine in which the bottom of the cavity is characterized by being configured to be tilted to a direction that Hiroshiku.