JPH041429A - Gasoline injection engine with auxiliary combustion chamber - Google Patents

Abstract

PURPOSE:To make good combustion regardless of engine load by specifying the volume of an auxiliary combustion chamber to that of a whole combustion chamber, and also specifying a partial gasoline injection direction and injection timing respectively to expand a uniform combustible mixed gas region according to the increase of an engine load. CONSTITUTION:Main and auxiliary combustion chambers 5 and 10 are formed between the flat top surface of a piston 3 and the flat internal wall surface of a cylinder head 4, and in the cylinder head 4 respectively. In this case, the volume of the auxiliary combustion chamber 10 is formed almost equal to that of the main combustion chamber 5, and the volume of the auxiliary combustion chamber 10 is formed so as to be an degree from 30 - 70% of that of a whole combustion chamber. A gasoline injection direction from a fuel injection valve 13 is directed in the main combustion chamber 5 through an injection port 11. An injection period is relatively short at the time of engine low load operation, consequently injection is made when the air flow velocity in the injection port 11 is considerably fast. Meantime the injection is conducted when the air flow velocity in the injection port 11 is slow at the time of engine high load operation.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a gasoline injection engine with a sub-combustion chamber.

[Conventional technology]

A two-cycle gasoline injection engine with a sub-combustion chamber material, which is equipped with a sub-combustion chamber that communicates with the main combustion chamber through a nozzle, and a fuel injection valve and a spark plug are arranged in the sub-combustion chamber so that gasoline is injected from the fuel injection valve. is publicly known (Japanese Unexamined Patent Publication No. 49-1337
(See Publication No. 06). In this two-stroke engine, the sub-combustion chamber occupies most of the volume of the entire combustion chamber, and therefore, in this two-stroke engine, substantially all combustion takes place within the sub-combustion chamber.

[Problem to be solved by the invention]

By the way, in an open chamber type combustion chamber, when the engine is operated at low load, a homogeneous combustible mixture area is formed around the spark plug a, as shown in FIG. As the engine load increases, the homogeneous combustible mixture area is expanded and the area consisting only of air is reduced, and the engine is operated under high load. It is known that if it is possible to create a homogeneous combustible mixture within the entire combustion chamber, extremely good combustion can be achieved regardless of the engine load. However, in reality, it is difficult to form a homogeneous combustible mixture region only in a partial area of the oven chamber type combustion chamber, as shown in FIG. Because it spreads throughout the room, the air-fuel mixture becomes diluted and difficult to ignite.In this case, if a rich mixture area is successfully formed around spark plug a, ignition is possible, but the mixture is not in the rich air-fuel mixture area. Since the mixture becomes extremely thin around the combustible mixture, it is not possible to achieve good combustion as in the case where a uniform combustible mixture region is formed as shown in FIG. 9(A). 1337
The two-cycle engine described in the 06 publication also has the same oven chamber type combustion chamber, and cannot form a homogeneous combustible mixture region as shown in Figure 9 (A) during low engine load operation. , thus it is difficult to obtain good combustion.

However, as shown in Figures 9 (D) to (F), in an internal combustion engine equipped with a sub-combustion chamber d, the space is closed to the extent that the sub-combustion chamber d is formed, so when the engine load is low and the (D)
As shown in (E), a uniform combustible mixture region is formed around the spark plug a, and a region C consisting only of air is easily formed around this uniform combustible mixture region. In this case, it is actually quite difficult to form a homogeneous combustible mixture region in a part of the auxiliary combustion chamber d as shown in FIG. 9(D), but as shown in FIG. 9(E), It is quite possible to form a homogeneous combustible mixture region in the sub-combustion chamber d.

Although it is difficult to continuously and gradually expand the homogeneous combustible mixture region as shown in FIGS. 9(D) to (F) in response to an increase in engine load, the present invention aims to achieve this goal to some extent. As the engine load increases, the homogeneous air-fuel mixture region is gradually changed from only in the sub-combustion chamber d to as shown in FIG. 9(F), as shown in FIG. 9(E). The purpose is to expand the combustion chamber f, thereby achieving as close to ideal combustion as possible.

[Means to solve the problem]

In order to achieve the above object, the present invention includes an auxiliary combustion chamber that communicates with the main combustion chamber through a nozzle, a fuel injection valve and a spark plug are arranged in the auxiliary combustion chamber, and gasoline is injected from the fuel injection valve. In such a gasoline injection engine with an auxiliary combustion chamber, the volume of the auxiliary combustion chamber is approximately 30% to 70% of the total volume of the combustion chamber, and at least part of the gasoline injection direction from the fuel injection valve is directed through the nozzle. The fuel is directed into the main combustion chamber, and when the engine is running at low load, the airflow flowing into the auxiliary combustion chamber from the nozzle substantially remains in the auxiliary combustion chamber so that all the injected gasoline remains within the auxiliary combustion chamber when the airflow velocity is relatively high. Gasoline is injected from the injector, and when the engine is running at high load, the injection timing is advanced so that some of the injected gasoline flows into the main combustion chamber. Gasoline is injected from the injection valve.

[For production]

As the engine load increases, the homogeneous combustible mixture region expands from only the auxiliary combustion chamber to the main combustion chamber.

〔Example〕

Referring to FIGS. 1 to 3, 1 is a two-stroke internal combustion engine body, 2 is a cylinder block, 3 is a piston, 4 is a cylinder head, and 5 is a gap between the flat top surface of the piston 3 and the flat inner wall surface of the cylinder head 4. 6 is a pair of intake valves, 7 is an intake boat, 8 is a pair of exhaust valves, 9 is an exhaust boat, 10 is a sub-combustion chamber formed in the cylinder head 4, 11 is a main combustion chamber formed in the cylinder head 4; A nozzle port communicating the auxiliary combustion chamber 10 and the main combustion chamber 5, 12 a spark plug disposed within the auxiliary combustion chamber 10, and 13 a fuel injection valve disposed at the top of the auxiliary combustion chamber 10,
As shown in FIG. 3, a mask wall 14 is formed on the inner wall surface of the cylinder head 4 to cover the opening of the air intake valve 6 on the exhaust valve 8 side during the period when the air intake valve 6 is substantially fully open. In the embodiment shown in FIGS. 1 to 3, the volume of the sub-combustion chamber 10 is approximately equal to the volume of the main combustion chamber 5;
The zero volume can be formed to be about 30% to 70% of the total combustion chamber volume. In addition, in the embodiments shown in FIGS. 1 to 3, the compression ratio is approximately T0, and the ratio of the volume of the auxiliary combustion chamber 10 to the area of the nozzle 11 (volume of the auxiliary combustion chamber 10 (cd)/nozzle nozzle Area of 11 (c
d)) ranges from 5 cm to 50 m or less.

In the embodiment shown in FIGS. 1 to 3, the exhaust valve 8 opens before the intake valve 6 and closes before the intake valve 6, as shown in FIG. When the intake valve 6 opens, fresh air flows into the combustion chamber 5 from the opening of the intake valve 6 on the opposite side of the mask wall 14, and then this fresh air flows along the inner wall surface of the cylinder bore below the intake valve 6. After descending, it advances along the top surface of the piston 3 as shown by the arrow W in FIG. By providing the mask wall 14 in this way, fresh air flows in a loop inside the combustion chamber 5,
In this way, good scavenging will be achieved. Then, a while after the piston 3 begins to rise past the bottom dead center BDC, the exhaust valve 8 closes. By the time the exhaust valve 8 closes, the opening area of the air supply valve 6 has become considerably smaller.
Therefore, when the exhaust valve 8 is about to close, the compression of the air in the main combustion chamber 5 is started by the upward movement of the piston 3. When the compression action of the air in the main combustion chamber 5 is started and the pressure in the main combustion chamber 5 becomes higher than the pressure in the sub-combustion chamber 10, the air in the main combustion chamber 5 flows through the nozzle 11 into the sub-combustion chamber 10. begins to flow inside. The pressure difference between the compressed air pressure in the main combustion chamber 5 and the pressure in the auxiliary combustion chamber 10 gradually increases as the piston 3 rises, and this pressure difference is BTDC before top dead center.
It reaches its maximum at about 30°. Therefore, as shown in FIG. 5, the flow velocity V of the air flowing through the nozzle 11 from the main combustion chamber 5 to the auxiliary combustion chamber 10 gradually increases as the piston 3 rises from around the time when the exhaust valve 8 closes. The flow velocity V reaches its maximum at about 30 degrees BTDC before the top dead center.

By the way, in the embodiment shown in FIGS. 1 to 3, the direction of gasoline injection from the fuel injection valve 13 is directed into the main combustion chamber 5 through the nozzle 11, and therefore the direction shown in FIGS.
As indicated by F in the figure, gasoline is injected from the fuel injection valve 13 into the main combustion chamber 5 through the nozzle 11. In FIG. 5, T1 indicates the injection period during low engine load and low speed operation, and T2 indicates the injection period during engine low load and high speed operation. Furthermore, T indicates the injection period during high-load, low-speed operation of the engine, and T4 indicates the injection period during high-speed operation of the engine with high load. Note that, between low-load engine operation and high-load engine operation, the injection timing becomes earlier as the engine load increases.

As can be seen from FIG. 5, when the engine is operating at low load, the injection action is completed at 30° BTDC before top dead center, that is, near the point where the air flow velocity V in the nozzle 11 is at its maximum.

When the engine is operating at low load, the injection period is relatively short, and therefore the injection is performed when the air flow velocity V in the nozzle 11 is quite high. If injection is performed when the air flow velocity V in the nozzle 11 is quite high as described above, the injected gasoline F will flow from the nozzle 11 into the auxiliary combustion chamber 10 as shown in FIG.
The inward air flow Z is prevented from entering the main combustion chamber 5. Therefore, at this time, the injected gasoline F remains in the sub-combustion chamber 10 and forms a homogeneous combustible mixture within the sub-combustion chamber 10. On the other hand, at this time, the main combustion chamber 5 is filled only with air, in fact only with air containing residual burnt gas, and therefore a homogeneous combustible mixture region is formed in a part of the combustion chamber during low engine load operation. will be done. This homogeneous combustible mixture is ignited by the spark plug 12, thus achieving good combustion.

On the other hand, as shown in FIG. 5, when the engine is operating under high load, the injection timing is earlier than when operating under low load, and the injection action is completed, for example, at about 80° BTDC at the top dead center. Therefore, during high-load engine operation, the nozzle 1 is smaller than during low-load operation.
Injection takes place when the air flow velocity V within 1 is slow. If injection is performed when the air flow velocity V in the nozzle 11 is slow as described above, a part of the injected gasoline F will enter the main combustion chamber 5 as shown in FIG. A homogeneous combustible mixture is formed within the combustion chamber 10 and the main combustion chamber 5.

Therefore, when the engine is operated under high load, the entire combustion chamber is filled with a uniform air-fuel mixture, so that good combustion can be achieved.

In this way, the present invention utilizes changes in the air flow velocity V flowing through the nozzle 11 to expand the homogeneous combustible mixture region as the engine load increases, albeit in stages. Even when gasoline is injected into the cylinder, good combustion can be obtained regardless of the engine load.

FIG. 8 shows a case where the gasoline injection angle is made relatively wide so that only a portion of the injected gasoline F passes through the nozzle 11 and heads into the main combustion chamber 5. Even in this case, the injection timings are T+ and T2 in FIG.

T3 is set as shown by T-.

〔Effect of the invention〕

Since the homogeneous combustible mixture region can be expanded in stages as the engine load increases, good combustion can be achieved regardless of the engine load.

[Brief explanation of drawings]

Figure 1 is a side sectional view of the two-stroke engine taken along line I-I in Figure 2, Figure 2 is a bottom view of the cylinder head in Figure 1, and Figure 3 is when the piston is at bottom dead center. ■ in Figure 2 of
A cross-sectional view taken along the line - ■, Figure 4 is a diagram showing the opening timing of the supply and exhaust valves, Figure 5 is a diagram to explain the injection timing, and Figure 6 is a diagram showing low load operation. FIG. 7 is a diagram showing a high-load operation, FIG. 8 is a side sectional view of another embodiment, and FIG. 9 is a diagram for explaining the combustion method. 5... Main combustion chamber, 10... Sub-combustion chamber, 11.
...Nozzle port, 12... Spark plug, 13... Fuel injection valve. Body i! Figure l-2 Figure 3 Figure 2 Figure Figure (A) (D) (B) (E) (C) (F) Figure

Claims (1)

[Claims] In a gasoline injection engine with a sub-combustion chamber, the sub-combustion chamber communicates with the main combustion chamber through a nozzle, and a fuel injection valve and a spark plug are arranged in the sub-combustion chamber so that gasoline is injected from the fuel injection valve. The volume of the auxiliary combustion chamber is set to about 30% to 70% of the volume of the entire combustion chamber, and at least part of the gasoline injection direction from the fuel injection valve is directed into the main combustion chamber through the nozzle, thereby reducing the engine temperature. During load operation, gasoline is injected from the fuel injection valve when the flow velocity of the air flow is relatively high so that all the injected gasoline substantially remains in the sub-combustion chamber due to the air flow flowing into the sub-combustion chamber from the nozzle, thereby reducing the engine height. During load operation, the injection timing is advanced so that some of the injected gasoline flows into the main combustion chamber, and gasoline is injected from the fuel injection valve when the air flow velocity is slower than when the engine is running at low load. Gasoline injection engine with combustion chamber.