JPS5926772B2 - Pre-chamber internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving combustion performance in a pre-chamber internal combustion engine, particularly in a pre-chamber diesel engine in which fuel is injected into an air vortex generated in the pre-chamber for ignition and combustion.

An example of a conventional pre-chamber type diesel engine is shown in FIGS. 1 and 2.

In such an auxiliary chamber type diesel engine, a fuel injection valve 8 and a glow plug 4 that preheats the inside of the auxiliary combustion chamber 5 at the time of starting the engine are provided facing into the auxiliary combustion chamber 5 recessed in the cylinder head 1. At the same time, the sub-combustion chamber 5 communicates with a main combustion chamber 7 formed on the upper surface of the piston 2 via a communication hole 6 .

3 is a cylinder. During operation of the engine, air in the main combustion chamber T flows into the auxiliary combustion chamber 5 through the communication hole 6 during the latter half of the compression stroke of the piston 2, producing a vortex flow A.

When fuel is injected from the fuel injection valve 8 along the direction of the vortex A, the fuel swirls in the sub-combustion chamber 5 along with the vortex A.

In this case, since the mixture is generated using only the vortex A, the generation of the mixture tends to be delayed, which lengthens the ignition delay period and deteriorates the initial combustion.

In other words, since the air-fuel mixture generated during this long ignition delay period is instantaneously combusted, the maximum gas pressure in the auxiliary combustion chamber 5 and the rate of increase in gas pressure become large.

As a result, engine vibration and noise become excessive, and at the same time, soot becomes more likely to be generated.

Even if the spray angle α of the fuel injector 8 is increased to compensate for such drawbacks, most of the fuel is distributed near the center line of the spray, so a small portion around the spray is affected by the air vortex A. At present, the effect of promoting fuel dispersion and atomization is small and it is not possible to promote air-fuel mixture formation simply by intersecting with .

In view of the above, the present invention provides a pre-combustion internal combustion engine that suppresses the rise in maximum cylinder pressure and reduces engine vibration, noise, etc. by improving the mixing of air vortex and fuel spray in the sub-combustion chamber. It was developed with the purpose of This is because the center line intersects the streamline of the air vortex in the diagonal downstream direction.

One embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

1 is the cylinder head, 2 is the piston, 3 is the cylinder, 5
1 is a sub-combustion chamber recessed in the cylinder head, 7 is a main combustion chamber, and 6 is a communication hole that communicates the sub-combustion chamber 5 with the main combustion chamber 7, and these structures are conventional ones. It is similar to

Reference numeral 8 denotes a fuel injection valve for injecting fuel into the auxiliary combustion chamber 5, and the fuel injection valve 8 has a planar position within the auxiliary combustion chamber 5 that is deviated from the center line 6a of the communication hole 6, and is further away from the center line 6a of the communication hole 6. It is installed at a position where the center line of the injected fuel spray intersects the streamline of the air vortex A in the diagonally downstream direction.

That is, the fuel injection valve 8 is installed so that the center line of the fuel spray injected from the fuel injection valve 8 intersects the air vortex A in the downstream direction of the vortex A at an angle Y.

When operating a sub-combustion internal combustion engine with such a configuration, the air in the main combustion chamber 7 is compressed as the piston 2 rises during the compression stroke of the piston 2.・Because there is a difference in power between the sub-combustion chambers 5,
Air in the main combustion chamber 7 moves into the sub-combustion chamber 5 through the communication hole 6.

The moved air is stored in the sub-combustion chamber 5.
produces a vortex A along the inner wall of the

Fuel is injected into this vortex A from a fuel injection valve 8 installed with a fuel nozzle facing into the sub-combustion chamber 5.

The injected fuel spray intersects and collides with the air vortex A, causing small turbulence between the fuel and air, which promotes atomization and dispersion of the fuel spray.

FIG. 5 shows another embodiment of the present invention, in which two fuel injection valves 8ay sb are sandwiched between the center line 6a of the communication hole 6 in the auxiliary combustion chamber 5, and the individual fuel injection valves 8ap
Center line of fuel spray injected from sb Da p Db
are installed at positions where they intersect with the air vortex A in a diagonal downstream direction.

In this case, since the fuel spray collides with both sides of the air vortex A, atomization and dispersion of the fuel spray are further promoted than in the first embodiment.

As described above, the auxiliary chamber type internal combustion engine according to the present invention has a fuel injection valve whose planar position in the auxiliary combustion chamber is off the center line of the communication hole, and where the center line of the fuel spray is diagonally downstream with respect to the air vortex. (1) Near the end of the piston's compression stroke, the fuel collides with the air vortex in the sub-combustion chamber from an oblique direction, causing small turbulence and at the same time atomizing the fuel. , promotes dispersion, and improves air utilization efficiency for mixture formation, ignition, and mastication.

Therefore, the maximum inflow and inflow rate of rise in the cylinder are reduced, and vibration and noise of the engine can be reduced.

(2) Since mixture formation is promoted, fuel injection timing can be delayed, and from this point of view as well, engine vibration and noise are reduced.

(3) To reduce gas flow loss in the communication hole,
The weakening of the air vortex in the sub-combustion chamber, which occurs when the passage area of the communication hole is expanded, can be compensated for by utilizing the turbulence generated by causing the fuel spray to cross and collide diagonally downstream with the air vortex. can do.

This practical effect can be achieved.

[Brief explanation of the drawing]

Figures 1 and 2 show one example of a conventional pre-chamber diesel engine.
As an example, FIG. 1 is a cross-sectional view of the vicinity of the sub-combustion chamber, and FIG. 2 is a cross-sectional view taken along line BB in FIG. 1. 3 and 4 show one embodiment of the present invention, with FIG. 3 being a sectional view corresponding to FIG. 1, and FIG. 4 being a sectional view taken along the line CC in FIG. 3. FIG. 5 is a sectional view corresponding to FIG. 4 showing another embodiment of the present invention. 1... Cylinder head, 2... Piston, 3... Cylinder, 4... Glow plug, 5... Sub-combustion chamber, 6 ...Communication hole, 7...Main combustion chamber, 8, 8a. 8b...Fuel injection valve, A...Air vortex, Dt DayDb...Fuel spray center line.

Claims (1)

[Claims] 1. In an internal combustion engine comprising a sub-combustion chamber that communicates with a main combustion chamber via a communication hole and a fuel injection valve that injects fuel into an air vortex generated within the sub-combustion chamber, the fuel injection valve: The planar position in the auxiliary combustion chamber is located away from the center line of the communicating hole, and the center line of the fuel spray injected from the fuel injection valve intersects the vortex in a diagonal downstream direction. A pre-chamber internal combustion engine.