JPH01271658A - Fuel injection device for engine - Google Patents

Abstract

PURPOSE:To improve the ignition performance of a mixture by providing a scavenging means for openingly controlling a control valve so as to feed fuel or a mixture around an ignition plug of a combustion chamber midway in a compression stroke while also openingly controlling the control valve so as to feed the mixture into the recessed portion of the combustion chamber during an intake stroke. CONSTITUTION:Due to the upwardly recessed shape of the recessed portion 2a of a combustion chamber 2, a dilution gas is liable to stagnate therein. In a fuel injection valve 16 provided in this place, at the time of a compression stroke, the operation of its fuel feeding portion 16a is continued for a minute period of time after the closing action of a poppet valve 16f, leaving the mixture of fuel and pressure air in a fuel feeding passage 16c. After that, midway in an intake stroke (start of intake), a scavenging means 31 is operated to injectingly feed the remaining mixture from the passage 16c into the recessed portion 2a accompanying the opening action of the valve 16f, thereby scavenging the dilution gas with the mixture. Therefore, the ignition performance of the mixture can be improved.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a fuel injection device for an engine, and in particular, it unevenly distributes a rich mixture around a spark plug in a combustion chamber to perform stratified combustion of the mixture. - Concerning the improvement of things.

(Prior art) Generally, when carrying out stratified combustion of an air-fuel mixture, a fuel injection valve is placed facing into the combustion chamber, and fuel is supplied from the fuel injection valve force to the area around the spark plug in the combustion chamber during the compression stroke. , the rich mixture is unevenly distributed around the spark plug. In this case, the position of the fuel injector facing into the combustion chamber may be the side or top of the combustion chamber, but if it is difficult to locate it on the side of the combustion chamber due to interference with engine auxiliary equipment, For example, as disclosed in Japanese Utility Model Application Publication No. 58-2363, it is arranged at the top of the combustion chamber.

(Problem to be Solved by the Invention) By the way, when the fuel injection valve is arranged at the top of the combustion chamber as described above, the intake valve and the exhaust valve are arranged near the top of the combustion chamber, and the spark plug is also arranged at the top. If it is difficult to arrange the fuel injector at the top of the combustion chamber due to the arrangement, the shape of the combustion chamber is changed and the top of the combustion chamber is recessed upward to form a recess. It is conceivable to place the spark plug and fuel injection valve in the

However, in this case, since the shape of the recess is upwardly recessed, dilution gas tends to accumulate in the recess, and as a result, the amount of air around the spark plug becomes extremely small, making it difficult to inject and supply fuel. However, the air-fuel mixture is difficult to ignite, resulting in a decrease in ignition performance.

The present invention has been made in view of the above, and an object thereof is to improve the ignition performance of the air-fuel mixture by appropriately scavenging the dilution gas present in the recessed portion. In that case, when scavenging with air, there is a disadvantage that an air layer is formed in the recessed part, and this air layer tends to inhibit the propagation of the flame during the explosion stroke, so it is preferable to scavenge with the mixture. In addition, if scavenging is performed when there is an intake or exhaust flow, scavenging will be effectively carried out along with this flow, but from the viewpoint of preferable scavenging in the air-fuel mixture as described above, when there is an exhaust flow When scavenging air (when the intake valve and exhaust valve overlap), the air-fuel mixture is released into the atmosphere as is, resulting in a decrease in emissions.
It is desirable to select the scavenging timing when intake air flow is present.

(Means for Solving the Problems) In light of the above, the solution of the present invention is to form an upwardly recessed recess at the top of the combustion chamber, and arrange the spark plug and fuel injection valve in the recess. . The fuel injection valve has a configuration including a fuel supply section that supplies fuel, a fuel injection passage for injecting the fuel supplied from the fuel supply section around the spark plug of the combustion chamber, and the fuel injection passage. The fuel supply system is configured to include a pressurized air passage that opens to supply pressurized air, and a control valve that opens and closes a fuel supply passage downstream of the confluence with the pressurized air passage. Further, the control valve is controlled to open during the compression stroke so as to supply fuel or air-fuel mixture to the vicinity of the spark plug in the combustion chamber, so that the rich mixture can be unevenly distributed around the spark plug. Further, a scavenging means is provided for controlling the opening of the control valve so as to supply the air-fuel mixture to the recessed portion of the combustion chamber during the intake stroke.

(Function) With the above configuration, in the present invention, since the recess is formed at the top of the combustion chamber, the ignition plug and fuel injection valve can be moved into the combustion chamber even though the intake valve and exhaust valve are nearby. can be easily placed.

When carrying out stratified charge combustion of the air-fuel mixture, the control valve is controlled to open during the compression stroke. The mixture with pressurized air from the air passage is supplied to the vicinity of the spark plug in the combustion chamber through the fuel supply passage, and the rich mixture is unevenly distributed around the spark plug in the combustion chamber.

In that case, dilution gas tends to accumulate in the recessed part of the combustion chamber, but since the control valve is controlled to open by the scavenging means during the intake stroke, the fuel supplied from the fuel supply section to the fuel injection passage, The air-fuel mixture with the pressurized air supplied to the fuel injection passage via the pressurized air passage is injected and supplied to the recessed portion of the combustion chamber during this intake stroke. As a result, this air-fuel mixture is diffused throughout the combustion chamber from the depression along with the flow of intake air, and the dilution gas is effectively scavenged. Moreover, due to the scavenging by the air-fuel mixture as described above, there is no air layer in the recess during the subsequent compression stroke.
When the fuel or air-fuel mixture is injected and supplied around the spark plug in the recessed portion during the compression stroke, the flame propagation during the explosion stroke is performed well, and the ignition performance of the air-fuel mixture is effectively improved.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of an engine fuel injection system according to the present invention, where 1 is an engine, 2 is a cylinder 3 of the engine 1, and 2 is a cylinder 3 of the engine 1.
A combustion chamber 5 whose volume is variable by a piston 4 slidably inserted into the combustion chamber 5 has one end communicating with the atmosphere via an air cleaner 6 and the other end opening into the combustion chamber 2 to supply intake air. The intake passage 7 is an exhaust passage with one end communicating with the combustion chamber 2 and the other end open to the atmosphere for discharging exhaust gas. The intake passage 5 is provided with a throttle valve 8 that adjusts the intake air amount, and a fuel injection valve 9 that injects and supplies fuel downstream of the throttle valve 8. A catalyst device 10 for purification is provided. Furthermore, in the combustion chamber 2, an intake valve 12 is disposed at the opening of the intake passage 5, an exhaust valve 13 is disposed at the opening of the exhaust passage 7, and the top of the combustion chamber 2 is disposed. A recessed portion 2a recessed upward is formed.

An ignition plug 15 for igniting the air-fuel mixture and another fuel injection valve 16 are arranged in the recess 2a.

In addition, 20 is an air flow sensor that detects the amount of intake air on the upstream side of the throttle valve 8, 21 is an intake air temperature sensor that detects the intake air temperature, 22 is an opening sensor that detects the opening of the throttle valve 8, and 23 is a throttle valve. 8 is a negative pressure sensor that detects the intake negative pressure on the downstream side; 24 is a water temperature sensor that detects the engine cooling water temperature; 25 is arranged on the upstream side of the catalyst device 10 in the exhaust passage 7; An air-fuel ratio sensor 26 is a rotational speed sensor that detects the rotational angle (that is, the engine rotational speed) of the signal disk plate 1a connected to the output shaft of the engine 1 and rotating synchronously.

The detection signals of each of the sensors 20 to 26 (intake air amount signal ISa, intake air temperature signal ISt, throttle valve opening signal ISh, intake negative pressure signal tsb, cooling water temperature signal ISs, air-fuel ratio signal ISo, % edge) The two rotational speed signals l5n) are each input to the controller 30.

Inside the controller 30, there are an input/output board 31 for each of the detection signals and control signals, a ROM 32, a RAM 33,
and a CPU 34, and the controller 30 controls the operation of the two fuel injection valves 9.16.

Next, the fuel injection valve 16 disposed in the recess 2a of the combustion chamber 2
The configuration is shown in detail in FIG. The fuel injection valve 16 includes a fuel supply section 16a that injects and supplies an amount of fuel according to a control signal (injection pulse) transmitted from the controller 30, and fuel supplied from the fuel supply section 16a. A supply control unit 1 that controls the supply to the combustion chamber 2 and its stop.
6b. The latter supply control section 16b has a fuel injection passage 16e formed in its central portion on an extension of the axis of the fuel supply section 16a, and the rear end of the fuel injection passage 16c is connected to the fuel supply section 16c. The front end of the portion 16a faces the recess 2a of the combustion chamber 2. The fuel injection passage 16c injects the fuel supplied from the fuel supply section 16a into the recessed part 2a of the combustion chamber 2 through the fuel supply passage 16c, and supplies this fuel around the spark plug 15. I try to do that.

The supply control section 16b also includes a fuel injection passage 16c.
A pressurized air passage 16d that intersects the axis of the fuel supply portion 16a at a predetermined narrow angle is opened at the rear end, and pressurized air is constantly supplied to the pressurized air passage 16d.

Further, at the tip of the fuel injection passage 16c (that is, on the downstream side of the confluence with the pressurized air passage 16d), a tip opening 16c1 having a shape that opens diagonally outward is opened and closed to open and close the fuel supply passage.
A control valve 16e is arranged to open and close the valve 6c. The control valve 16e includes a poppet valve 16f that opens and closes the tip opening 16c1.
It has a spring 16f2 that urges f1 in the seating direction. Further, a hollow suppressing member 16g is disposed at the rear end of the valve body 16f1 of the poppet valve 16f, and the pressing member 16g is moved in the front and rear direction by electromagnetic force on the outside of the pressing member 16g. An excitation coil 16h is arranged to cause the When the excitation coil 16h is energized, the suppressing member 16g is moved forward by electromagnetic force to close the poppet valve 16.
The poppet valve 16f is opened by disengaging the valve body 16F+ of the valve f against the biasing force of the spring 16f2, thereby opening the tip opening 16c1 of the fuel supply passage 16c and supplying fuel or air-fuel mixture. While spraying is supplied from the tip opening 16c1 to the recess 2a of the combustion chamber 2 at a wide spray angle,
When the excitation coil 16h is de-energized, the valve body 16ft of the poppet valve 16f is moved rearward together with the pressing member 16g by the biasing force of the spring 16'2, and is seated to close the poppet valve 16f, thereby opening the fuel supply passage 16c. The tip opening 16c+ of the combustion chamber 2 is closed to stop the injection supply to the recess 2a of the combustion chamber 2.

As indicated by the symbol A in the fuel injection timing characteristics shown in FIG. 3, the control valve 16e controls the poppet valve 16f to be opened by the controller 30 during the compression stroke (particularly at the end of the compression stroke) to control the air-fuel mixture. It is controlled to open so that it is supplied to the recessed part 2a (around the spark plug 15) of the combustion chamber 2. As shown in FIG. 4, the detailed settings are such that the poppet valve 16f is first controlled to open, then the fuel supply section 16a is controlled to operate with a slight delay, and even after the poppet valve 16f is controlled to close, the operation is controlled for a short period of time. Operation control of the fuel supply section 16a continues. That is, in order to unevenly distribute the rich mixture around the spark plug 15, the mixture is injected into the recess 2a of the combustion chamber 2 during the compression stroke, and the fuel supply passage 1
6c is closed, the fuel supply from the fuel supply section 16a is continued, and a predetermined amount of fuel is left in the fuel supply passage 16c to be mixed with pressurized air and left as an air-fuel mixture.

Further, the fuel injection valve 9 disposed in the intake passage 5 is
As shown by symbol B in the figure, during the intake stroke, especially at the beginning of intake where the intake flow velocity is high, the controller 30 controls the operation so as to inject and supply fuel in an amount that should result in a lean mixture corresponding to the amount of intake air. It is something that will be done. Furthermore, the poppet valve 16f of the control valve 16e is controlled to open in synchronization with the fuel injection timing of the fuel injection valve 9 of the intake passage 5, and the air-fuel mixture remaining in the fuel supply passage 16c is controlled to flow during this period (symbol in the figure). The operation is controlled by the controller 30 so that the fuel is injected into the recess 2a of the combustion chamber 2 during the period indicated by B).

With the above configuration, the air-fuel mixture remaining in the fuel supply passage 16c is transferred to the recessed part 2a of the combustion chamber 2 (around the spark plug 15) by opening the poppet valve 16f during the intake stroke (particularly at the beginning of intake).
A scavenging means 31 is configured to control the opening of the control valve 16e so that the air is supplied to the air.

Therefore, in the above embodiment, during the intake stroke (at the beginning of intake), fuel is injected and supplied from the fuel injection valve 9 of the intake passage 5, and a uniform lean mixture corresponding to the amount of fuel is supplied to the combustion chamber 2. At the same time, during the compression stroke (especially at the end), the fuel injection valve 16 disposed in the recess 2a of the combustion chamber 2
The poppet valve 16f of the fuel supply section 16 is opened.
A small amount of fuel is supplied from the tip opening 16c1 of the fuel supply passage 16c to the recess 2a at a wide spray angle.

As a result, the spray (air mixture) supplied from the fuel supply passage 16'c has a short flight distance, is well atomized, and remains in the recessed part 2a of the combustion chamber 2, and when viewed from the entire combustion chamber 2, The rich mixture will be unevenly distributed in the depression 2a,
Good stratification of the air-fuel mixture is achieved.

In this case, since the recess 2a of the combustion chamber 2 has an upwardly recessed shape, dilution gas tends to accumulate in the recess 2a. However, in the fuel injection valve 16 disposed in the recessed portion 2a, during the compression stroke, the fuel supply portion 16
The operation a continues for a short time even after the poppet valve 16f closes, and a mixture of fuel and pressurized air remains in the fuel supply passage 16c. Then, during the subsequent intake stroke (at the beginning of intake), the scavenging means 31 operates, and the remaining air-fuel mixture is injected and supplied from the fuel supply passage 16c to the recess 2a of the combustion chamber 2 as the poppet valve 16f opens. Therefore, the dilution gas stagnating in the recessed portion 2a is scavenged with this air-fuel mixture.

Here, since scavenging is performed during the intake stroke (at the beginning of intake), scavenging by this air-fuel mixture is effectively carried out along with the flow of intake air, and as a result, almost no dilution gas is present in the recessed portion 2a. cease to exist. Furthermore, since the scavenging air-fuel mixture is not directly released into the atmosphere, good emission performance can be ensured. Moreover, since the scavenging is performed by the air-fuel mixture and there is no air layer in the recessed portion 2a, the flame propagation in the subsequent explosion stroke is performed well without being inhibited, and the ignition performance of the air-fuel mixture is improved. .

In the above embodiment, pressurized air is constantly supplied to the pressurized air passage 16d of the fuel injection valve 16 disposed in the recessed part 2a to form an air-fuel mixture in the fuel supply passage 16c. Although the fuel is supplied around the spark plug 15 during the compression stroke (at the end), it is of course possible to supply only fuel instead of supplying the air-fuel mixture during the compression stroke.

(Effects of the Invention) As explained above, according to the fuel injection device for an engine of the present invention, when forming an upwardly recessed part in which a spark plug and a fuel injection valve are to be disposed at the top of a combustion chamber, the above-mentioned A pressurized air passage is provided in the fuel injection valve, and the mixture is supplied from the fuel injection valve to the recessed portion during the intake stroke, which prevents the mixture from being released into the atmosphere and improves emission performance. It is possible to effectively scavenge the diluted solar gas that accumulates in the recessed part of the combustion chamber according to the flow of intake air, while ensuring that the flame during the explosion stroke does not form an air layer in the recessed part. It is possible to improve the propagation of the air and improve the ignition performance of the air-fuel mixture.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a general schematic diagram, FIG. 2 is a cross-sectional view of main parts showing a specific configuration of a fuel injection valve disposed in a recessed part of a combustion chamber, and FIG. 3 is a fuel injection valve. FIG. 4 is a diagram showing the temporal operational relationship between the fuel supply section of the fuel injector and the poppet valve disposed in the recessed part of the combustion chamber. DESCRIPTION OF SYMBOLS 1... Engine, 2... Combustion chamber, 2a... Recessed part, 15... Spark plug, 16... Fuel injection valve, 16
a...Fuel supply section, 16e...Fuel supply passage, 16
d... Pressurized air passage, 16e... Control valve, 16r.
...Poppet valve, 30...Controller, 31...
Scavenging means. Figure 3Δ Figure 4

Claims (1)

[Claims] 1) An upwardly recessed recess is formed at the top of the combustion chamber, and a spark plug and a fuel injection valve are disposed in the recess,
The fuel injection valve includes a fuel supply section that supplies fuel, a fuel injection passage for injecting the fuel supplied from the fuel supply section around the spark plug of the combustion chamber, and a fuel injection passage that is opened to the fuel injection passage and is It includes a pressurized air passage to which pressurized air is supplied, and a control valve that opens and closes a fuel supply passage on the downstream side of the confluence with the pressurized air passage. The scavenging means is controlled to open so as to supply the air-fuel mixture to around the ignition plug of the combustion chamber, and also includes a scavenging means that controls the control valve to open so as to supply the air-fuel mixture to the recessed portion of the combustion chamber during the intake stroke. fuel injection system for the engine.