JPH0555689B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the combustion chamber of an internal combustion engine, and particularly to an internal combustion engine that can use low cetane number and volatile fuel oil such as shaft oil, gasoline, and alcohol as fuel. Regarding the combustion chamber of.

[Prior Art] Generally, in engines such as diesel engines that inject fuel oil directly into the combustion chamber for combustion, it is difficult to improve the mixing of intake air (compressed air) and injected fuel oil. This is a condition for improving flammability. However, this is limited to fuel oil injected into the combustion chamber of the engine that has a high cetane number, such as light oil. In other words, when a low cetane number/volatile fuel oil such as gasoline or alcohol is used, it is vaporized and diffused at the same time as it is injected into the combustion chamber. It was difficult to generate a mixture of sufficient concentration to ignite and spread flame. Therefore, the amount of fuel injected has to be increased, which is undesirable from the viewpoint of fuel efficiency and output. One possible solution to this problem is to throttle the intake air, but this has not been used in direct injection engines because throttling the intake air increases the pumping loss of the engine.

Therefore, in order to solve the above-mentioned problems, the present applicant has proposed a combustion chamber for an internal combustion engine (Japanese Patent Application No. 106944/1982).

This proposal, shown in FIG. 7, involves recessing the piston top 1 and arranging a main combustion chamber 2 and a sub-combustion chamber 3 in parallel, which communicate with each other, and injecting fuel oil into the respective combustion chambers 2 and 3. A combustion chamber of an internal combustion engine is constructed by providing a fuel injection nozzle 4 for igniting the fuel oil, and a spark plug 15 for igniting the fuel oil in the auxiliary combustion chamber 3.

[Problems to be Solved by the Invention] The above proposal uses a spark plug to ignite and burn the air-fuel mixture trapped in the sub-combustion chamber with the swirl during light loads, and to ignite the flame within the sub-combustion chamber during medium and high loads. This allows flame propagation to the air-fuel mixture in the main combustion chamber via the bank part, thereby achieving stable combustion.

However, the presence of the bank part that attempts to confine volatile fuel oil in the sub-combustion chamber slightly slows down the speed of flame inflow into the main combustion chamber.
The output and fuel efficiency were reduced by the amount of this delay. Therefore, there has been a need for a combustion chamber for an internal combustion engine that solves this problem and provides combustion characteristics equal to or better than those of a gasoline engine.

[Object of the Invention] The present invention was created to solve the above problems.

An object of the present invention is to have a main combustion chamber and a sub-combustion chamber recessed in the top of the piston and installed side by side, and to quickly introduce flame from the sub-combustion chamber to the main combustion chamber through the bank portion that forms the peripheral side walls of each other. It is an object of the present invention to provide a combustion chamber for an internal combustion engine that can properly burn low cetane number, volatile fuel oil such as gasoline or alcohol in all operating load ranges including when starting the engine by providing a communication hole.

[Summary of the Invention] A main combustion chamber that is deeply recessed at the top of the piston, and a shallow recess that is provided at the top of the piston adjacent to the main combustion chamber, the volume of which is smaller than the main combustion chamber. The formed auxiliary combustion chamber, and a bank portion provided by recessing the upper part of each side wall between the auxiliary combustion chamber and the main combustion chamber from above in order to communicate the auxiliary combustion chamber and the main combustion chamber with each other. This is a fuel injection nozzle that is installed facing this bank and is configured to inject a spray of low cetane number, volatile fuel such as gasoline or alcohol. The injection direction is determined so that the atomized fuel collides with the inner wall outside the center of the sub-combustion chamber in the forward direction of the swirl to form a fuel film on the inner wall, and the injection direction exceeds a predetermined load. When this occurs, atomized fuel having a fuel particle size larger than the atomized fuel is collided in the forward direction of the swirl in the main combustion chamber and toward the inner wall outside the center of the main combustion chamber. a fuel injection nozzle configured with a main injection port whose injection direction is determined so as to form a combustion film on the inner wall; and an ignition means provided with an ignition part located within the auxiliary combustion chamber; A communication hole is provided at the lower part of the bank portion and is inclined downward so as to guide the flame of the auxiliary combustion chamber from the bottom of the auxiliary combustion chamber to the bottom of the main combustion chamber.

In other words, in the present invention, the auxiliary combustion chamber is subjected to combustion under any usage load, the auxiliary combustion chamber performs slow evaporative combustion, and when a predetermined load is exceeded, the main combustion chamber is combusted and the main combustion chamber is However, slow evaporative combustion is performed, and for this purpose, the volume of the sub-combustion chamber is made smaller than that of the main combustion chamber, and the sub-combustion chamber is filled with atomized fuel spray that has good evaporation under all operating loads. When a predetermined load is exceeded, a fuel spray with a larger fuel particle size than the atomized fuel spray is supplied to the combustion chamber, and a partition wall between the main combustion chamber and the sub-combustion chamber is provided. A bank part is provided above the bank part so as to communicate with the combustion chamber. The present invention does not aim to spread the fuel supplied to the bottom of the main combustion chamber by the flame moving from the bottom of the sub-combustion chamber to the bottom of the main combustion chamber and promote its evaporation; While confining the air-fuel mixture and performing slow combustion independently in the auxiliary combustion chamber, in order to eliminate the adverse effects of flame propagation to the main combustion chamber due to the bank part, the flame in the auxiliary combustion chamber is used for main combustion at the bottom of the bank part. A communicating hole is formed so as to be inclined downward so that it can be guided to the bottom of the chamber. In other words, the auxiliary combustion chamber is formed by recessing the top of the piston, and the auxiliary combustion chamber and the main combustion chamber are communicated with each other by the bank, so there is no hole in the communication hole that connects the main combustion chamber. It does not have the function of transmitting large pressures and only contributes to flame propagation.

[Embodiment] A preferred embodiment of a combustion chamber of an internal combustion engine according to the present invention will be described below with reference to the accompanying drawings.

In FIGS. 1 and 2, 1 is the top of the piston, 2 is the main combustion chamber, and 3 is the auxiliary combustion chamber.

As shown in the figure, a main combustion chamber 2 and a sub-combustion chamber 3
are recessed in the piston top portion 1 and are arranged side by side, and a part of the circumferential side wall that separates them from each other forms a bank portion 4 formed in an inclined shape. The main combustion chamber 2 and the sub-combustion chamber 3 are each open at the top, and the sub-combustion chamber 3 is recessed shallower than the main combustion chamber 2 with the piston top 1 as a reference plane. It is formed small relative to the volume of the combustion chamber 2. In this embodiment, the horizontal cross sections of the main combustion chamber 2 and the auxiliary combustion chamber 3 are formed, for example, in a circular shape.

Now, the feature of the internal combustion engine of the present invention is that it uses low cetane number and volatile fuel oil such as alcohol and gasoline to achieve good combustion during light loads, and that it is compatible with gasoline engines in all operating load ranges. The objective is to obtain a combustion chamber for an internal combustion engine that can achieve comparable output and fuel efficiency.

Therefore, the shape of the combustion chamber, the fuel injection nozzle, and the spark plug are related to each other as follows.

As shown in FIG. 3, the fuel injection nozzle 5 has a valve seat 8 on which the throttle portion 6a of the needle valve 6 is seated, at the tip of a nozzle body 7 that accommodates the needle valve 6 so as to be movable up and down. A fuel injection chamber 9 is formed which is raised in the axial direction from the seat 8 and is opened and closed by the throttle portion 6a.
However, a main injection port 13 is opened in the fuel injection chamber.

The nozzle diameter of the auxiliary nozzle 11 is formed to be extremely smaller than the nozzle diameter of the main nozzle 13, and the atomized fuel spray F ₁ with extremely small fuel particle diameter is sent from the auxiliary nozzle 11 to the main combustion chamber 2 from the main nozzle 13. Fuel spray F ₂ that has a predetermined penetration force for the created swirl S
The injection nozzle 5 is formed so that the needle valve 6 opens the sub-nozzle 11 when the lift value is below a predetermined lift value, and the main nozzle 13 is also opened when the lift value exceeds the predetermined lift value. It is a pintocks type structure.

On the other hand, a notch 12 is formed approximately in the upper center of the bank portion 4 to communicate the main combustion chamber 2 and the sub-combustion chamber 3 and to accommodate the fuel injection chamber 9 of the fuel injection nozzle 5.

In this embodiment, the nozzle body 7 of the fuel injection nozzle 5 is housed in a cylinder head (not shown), the sub-nozzle 11 faces approximately the center of the sub-combustion chamber 3, and the main nozzle 13 faces the main combustion chamber. It faces the inner wall 2a of No. 2 and the forward direction of the swirl S. In addition, a plug cap 15 is located approximately in the center of the sub-combustion chamber 3 and near the atomized fuel spray F1 from the sub-nozzle ₁₁ .
An ignition plug 15 is disposed at the position a and protrudes into the sub-combustion chamber 3.

On the other hand, the bank part 4 is opened from below the auxiliary combustion chamber 3 and communicates with the lower part of the main combustion chamber 2.
A communication hole 14 that allows the flame inside to flow into the main combustion chamber 2.
is formed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation of an embodiment of a combustion chamber of an internal combustion engine according to the present invention will be explained below based on the accompanying drawings.

When the engine is in a very low speed range when starting and under light load, the needle valve 6 of the fuel injection nozzle 5 shown in FIG. 3 is operated in the lift direction in accordance with the supplied fuel oil pressure. At the same time as this lift, the throttle portion 6a of the needle valve 6 moves away from the valve seat 8, and the sub-nozzle port 11 is opened. At this time, the stem portion 16 formed at the tip of the throttle portion 6a is defined to have a length l that forms a throttle period for closing the fuel injection chamber 9 until the needle valve 6 reaches a predetermined lift value. Therefore, the first
As shown in FIG. 2, atomized fuel spray F ₁ is injected into the sub-combustion chamber 3. When the needle valve 6 reaches a lift value exceeding the throttle period, the main injection port 13 is also opened and fuel spray F ₂ is injected into the main combustion chamber 2.

More specifically, as shown in FIGS. 4 and 5, the atomized fuel spray F ₁ in the sub-combustion chamber 3 is instantaneously vaporized upon contact with the high-temperature compressed air in the sub-combustion chamber 3. It is trapped together with the swirl S and generated in a moderately dense fuel vapor layer _E1 . This fuel vapor layer E ₁ is quickly combusted by the ignition of the spark plug 15 . At this time, the flame generated here flows into the main combustion chamber 2 through the communication hole 14.

On the other hand, while the needle valve 6 exceeds the predetermined lift value,
During high load, the fuel spray F ₂ is also injected into the main combustion chamber 2, so a part of the spray F ₂ flows into the fuel film flowing downstream of the swirl S along the inner wall 2a of the main combustion chamber 2. f, and the remaining part collides with the inner wall 2a of the main combustion chamber 2, is scattered, and is further atomized.
It is vaporized by the compressed air in the main combustion chamber 2. At this time, the outer surface of the fuel film f is also vaporized by the wall heat, so that a fuel vapor layer E ₂ of an appropriate concentration is generated in the main combustion chamber 2.

Now, the fuel vapor layer E ₂ in this main combustion chamber 2 is
The flame inflow from the communication hole 14 quickly ignites the flame, and as shown in FIG.
4 to the lower side of the main combustion chamber 2, and then further upward along the inner wall 2a of the main combustion chamber 2 to complete combustion.

Here, since the timing at which the flame propagates from the auxiliary combustion chamber 3 to the main combustion chamber 2 is such that the piston is set at approximately the top dead center position as shown in FIG. The lowering of the piston leads it to the squish area 17 formed between the cylinder head 18 and the piston top 1. That is, the reverse
S ₂ occurs. At this time, the flame in the main combustion chamber 2 is propagated from below the combustion chamber, so that the unburned air-fuel mixture being moved is completely combusted. Further, during light load, a small amount of steam in the sub-combustion chamber 3 is guided into the main combustion chamber through the communication hole 14, but it can be combusted by the oxidation catalyst and EGR (exhaust gas reburning).

Therefore, the low cetane number/volatile fuel oil can be burnt efficiently and rapidly in all operating load ranges including when starting the engine, thereby improving engine output and fuel efficiency.

[Effects of the Invention] As is clear from the detailed description above, the combustion chamber of the internal combustion engine of the present invention can exhibit the following excellent effects.

(1) In addition to stably burning low cetane number/volatile fuel oils such as alcohol and gasoline, the flame in the auxiliary combustion chamber can be quickly guided into the main combustion chamber, so it can be used under any operating load, including when starting the engine. It is possible to obtain high output and high fuel efficiency in this area.

(2) It is possible to obtain the same fuel efficiency as a diesel engine using light oil as fuel, and the same output performance as a gasoline engine using gasoline as fuel.

(3) Unburnt substances in the exhaust such as HC and aldehydes can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a preferred embodiment of a combustion chamber of an internal combustion engine according to the present invention, FIG. 2 is a schematic vertical sectional view of FIG. 1, FIG. 3 is a schematic sectional view of a fuel injection nozzle, and FIG.
6 to 6 are schematic diagrams showing the combustion process, and FIG. 7 is a schematic diagram showing the combustion chamber of a conventional internal combustion engine. In the figure, 1 is the piston top, 2 is the main combustion chamber, 3 is the sub-combustion chamber, 4 is the bank part, 5 is the fuel injection nozzle,
11 is a sub-nozzle, 13 is a main nozzle, 14 is a communication hole, 1
5 is a spark plug.

Claims (1)

[Claims] 1. A main combustion chamber that is deeply recessed at the top of the piston, and a sub-combustion chamber that is adjacent to the main combustion chamber and that is shallowly recessed at the top of the piston and whose volume is smaller than that of the main combustion chamber. A combustion chamber, a bank portion provided by recessing the upper part of each side wall between the auxiliary combustion chamber and the main combustion chamber from above in order to communicate the auxiliary combustion chamber and the main combustion chamber with each other, and the bank. A fuel injection nozzle is a fuel injection nozzle that is configured to inject a spray of low cetane number volatile fuel such as gasoline or alcohol. The injection direction is determined so that the atomized fuel collides with the inner wall outside the center of the sub-combustion chamber in the forward direction to form a fuel film on the inner wall. Atomized fuel having a fuel particle size larger than the atomized fuel is collided into the combustion chamber in the forward direction of the swirl and toward the inner wall outside the center of the main combustion chamber to form a combustion film on the inner wall of the main combustion chamber. a fuel injection nozzle configured with a main nozzle whose injection direction is determined so as to form a fuel injection nozzle, an ignition means provided with its ignition part located within the auxiliary combustion chamber, and a lower part of the bank part. A combustion chamber for an internal combustion engine, comprising: and a communication hole formed to be inclined downward so as to guide the flame of the auxiliary combustion chamber from the bottom of the auxiliary combustion chamber to the bottom of the main combustion chamber.