JP3055629B2 - Air fuel injection device for in-cylinder injection engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air fuel injection device for a fuel injection engine in which fuel is directly injected into a cylinder, and more particularly to the promotion of atomization of the injected fuel. The present invention relates to an improvement in an injection method capable of improving the measurement accuracy of an injection amount per combustion.

[Conventional technology]

In recent years, attention has been paid to an in-cylinder injection two-cycle engine in which fuel is directly injected into a cylinder together with compressed air, since it is advantageous in terms of measures against exhaust gas, fuel efficiency, and the like. As such an air fuel injection device for a fuel injection engine, there is a conventional one disclosed in Japanese Utility Model Laid-Open No. 2-24067, for example. This is configured such that an engine side opening of an air chamber communicating with a compressed air source is opened and closed by a needle valve, and fuel is injected by a fuel injection valve toward the air chamber or the compressed air passage. I have.

In the above-described conventional air fuel injection device, fuel from the fuel injection valve is injected toward the compressed air passage or the inner wall surface of the air chamber, and then the needle valve is opened, so that the fuel adheres to the inner wall surface of the air chamber or the like. The compressed granular fuel or the fuel remaining in the air chamber is sent into the cylinder by compressed air.

[Problems to be solved by the invention]

However, in the above-described conventional air fuel injection device, the injected fuel is attached to an inner wall surface of an air passage or the like, and the attached particulate fuel or the fuel remaining in the air chamber is transported by compressed air. Therefore, there is a problem that atomization of the injected fuel is likely to be insufficient, and there is also a problem that there is no guarantee that all the injected fuel is always fed into the cylinder, and that the measurement accuracy of the injection amount is low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide an air-fuel injection device for a fuel injection engine, which can promote atomization of injected fuel and improve the measurement accuracy of injected fuel. And

[Means for solving the problem]

The present invention has an air injection mechanism that injects compressed air from an air injection nozzle, and a fuel injection mechanism that injects fuel from a fuel injection nozzle, and injects air directly into a cylinder. In the fuel injection device, a mixing chamber of air and fuel is formed so as to be located immediately adjacent to the fuel injection nozzle and has a larger diameter than the fuel injection nozzle and the air injection nozzle, and the fuel injection nozzle and the air injection nozzle are formed in the mixing chamber. And an orifice portion is formed between the mixing chamber and the injection nozzle that opens to the combustion chamber of the mixture passage following the mixing chamber, and after the air injection mechanism starts air injection, the fuel injection mechanism The fuel injection is started, and the air injection is ended after the fuel injection is ended.

[Action]

ADVANTAGE OF THE INVENTION According to the air fuel injection device of the fuel injection engine which concerns on this invention, while injecting the fuel from a fuel injection mechanism toward the airflow by an air injection mechanism, the mixing chamber of fuel and air, ie, the said fuel, Is provided immediately adjacent to the fuel injection nozzle of the fuel injection mechanism, so that the injected fuel immediately mixes with the compressed air immediately after the injection, resulting in finer fuel and atomization. Promoted.

Further, since the fuel injection is started after the start of the air injection and the air injection is ended after the end of the fuel injection, the fuel is injected into the air flow and only during a period in which the air flow is flowing. Thus, all of the injected fuel is reliably supplied to the cylinder, and accordingly, the accuracy of measuring the injection amount is improved.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 are views for explaining an air-fuel injection device of a fuel injection engine according to an embodiment of the present invention. FIG. 1 is a sectional side view thereof, and FIG. FIG. 2 is a cross-sectional side view of an engine provided.

In the drawing, reference numeral 1 denotes an in-cylinder injection type 2 equipped with the apparatus of the present embodiment.
The engine 1 has a structure in which a cylinder body 3 and a cylinder head 4 are stacked and fastened on a crankcase 2 and an air fuel injection device 13 is mounted on the cylinder head 4.

A piston 6 is slidably inserted into a cylinder liner 5 fixedly inserted into the cylinder body 3.
A small end 7a of a connecting rod 7 is connected to the piston 6 by a piston pin 8. A large end 7b of the connecting rod 7 is connected to a crank arm 9a of a crank shaft 9 by a crank pin 10. The crank arm 9a is accommodated in a crank chamber 2a of the crank case 2, and the crank chamber 2a is provided in a scavenging passage formed in the cylinder body 3.
The cylinder liner 5 communicates with the scavenging port 5a which is opened in the middle of the cylinder liner 5 via 3a. An exhaust port 5b formed at a position opposite to the scavenging port 5a of the cylinder liner 5 is led to a front wall of the cylinder body 3 through an exhaust passage 3b. An exhaust valve 11 is rotatably disposed near the exhaust port 5b of the exhaust passage 3b.
Numeral 11 is for controlling the exhaust timing by changing the upper edge position of the exhaust port 5b.

The crankcase 2 is formed with an intake port 2b communicating with the crank chamber 2a, and a reed valve 18 is mounted on the intake port 2b together with a joint 19. The reed valve 18 has a V-shaped cross section, a valve seat 20 having an inlet 20a formed on each inclined surface thereof, a valve plate 21 made of a spring steel plate for opening and closing the inlet 20a, and a valve plate 21. And a stopper 22 for regulating the opening. The joint 19 has a throttle body 23 having a throttle valve 23a.
Is connected.

Above the exhaust valve 11 of the cylinder body 3,
Combustion stabilizer 17 for stabilizing combustion at low load
Is installed. The stabilizing device 17 is configured such that a suction body 25 having a suction hole 25a communicating with a pressure release hole 5c formed in the cylinder liner 5 is screwed into the cylinder body 3, and the pressure release hole 5c is inserted into the suction hole 25a. A needle valve 26 for opening and closing the side opening is inserted, and the needle valve 26 is configured to move forward and backward by a lever 28a rotatably supported on a shaft. The lever 28a is housed in the case 24, one end of which is connected to the needle valve 26, and the other end of which is a drive cable.
28 are connected. The drive cable 28 is connected to the control mechanism 30
And is connected to an actuator 29 whose rotation is controlled. 32 is a changeover switch, and 31 is a battery.
The suction hole 25a of the suction body 25 communicates with the scavenging passage 3a via a suction passage 27.

The air fuel injection device 13 includes an air-fuel mixture injection valve 14 that functions as an air injection mechanism, and a fuel injection valve 15 that is attached to the injection body 35 and functions as a fuel injection mechanism. In addition, 14a is an air rail connected to an air pump as a compressed air source, and 15a is a fuel rail connected to a fuel pump as a fuel source.

An injection nozzle 40a, which will be described later, of the air-fuel mixture injection valve 14 faces a combustion chamber 12 formed by an upper surface of the piston 6 and a combustion recess 4a recessed in a lower surface of the cylinder head 4. An ignition plug 16 is mounted on the cylinder head 4 so as to aim at the fuel injected from the injection nozzle 40a. And the pressure release hole 5c of the combustion stabilizing device 17
Is located near the lower part of the ignition plug 16.

The air-fuel mixture injection valve 14 has a structure in which a valve element 36 is inserted into an injection body 35 and a valve operating mechanism 37 that drives the valve element 36 in the vertical direction is housed. The injection body 35 is of an upper / lower two-part type composed of an upper body 38 and a lower body 39. An injection hole (mixture passage) 39a is formed in the axis of the lower body 39. The valve body is inside the injection hole 39a.
36 valve stems 36a are inserted. In addition, the above-mentioned injection hole 39a
A nozzle cylinder 40 is inserted into a lower end of the nozzle cylinder 40, and an orifice plate 41 is disposed at an upper end of the nozzle cylinder 40. The large-diameter portion 36b formed on the valve stem 36a is located in the orifice plate 41, and an orifice action can be obtained by a gap between the two. Further, a valve plate 36c formed integrally with the lower end of the valve rod 36a opens and closes the injection nozzle 40a at the lower end of the nozzle cylinder 40. Reference numeral 36d denotes a guide portion that slides on the inner surface of the nozzle cylinder 40.

A retainer 42 is fixed to the upper end of the valve stem 36a, and a cylindrical coil 43 is provided below the retainer 42.
Are arranged. Thus, when the coil 43 is energized, the retainer 42 is pulled downward, the valve body 36 is lowered, and the above-described valve operating mechanism 37 that opens the injection nozzle 40a is configured.

A mixing chamber 44 is formed near the connection between the upper and lower bodies 38 and 39 so as to obliquely intersect the injection hole 39a. The fuel injection nozzle 15b of the fuel injection valve 15 is located at the upper end opening 44a of the mixing chamber 44. Further, near the upper end opening 44a of the mixing chamber 44, an air injection nozzle 44c is formed so as to intersect at right angles with the upper end opening 44a, and the air injection nozzle 44c is connected to the air rail via a compressed air passage 44b.
Communicates with 14a. Thus, the upper end opening 44a of the mixing chamber 44
The fuel injection nozzle 15b and the air injection nozzle 44c of the fuel injection valve 15 face the front, so that the fuel injected from the fuel injection valve 15 collides with the compressed air immediately after the injection and mixes with the compressed air. .

Furthermore, a mixing promoting body 45 is inserted and arranged in the mixing chamber 44. The mixing accelerator 45 is a bottomed cylindrical member made of a porous member, and the fuel mixed with the compressed air passes through the fine holes from the inner surface 45a of the mixing accelerator 45 to the outer surface 45b. leak.

 Next, the operation and effect of this embodiment will be described.

In the engine 1 of this embodiment, the fuel is directly injected into the cylinder together with the compressed air at a predetermined timing by the air fuel injection device 13 in the compression stroke. In this case, at the injection start timing, first, the valve element 36 is driven by the valve mechanism 37 and descends, the injection nozzle 40a is opened, and the compressed air flows through the air injection nozzle 44c, the mixing chamber 44, and the injection hole 39a. Injection nozzle
Injection into the combustion chamber 12 is started from 40a. With the compressed air flowing in this way, the fuel injection nozzle of the fuel injection valve 15
15b is opened, and the injected fuel is injected from the nozzle 15b into the air flow. Therefore, immediately after the injection, the injected fuel collides with the compressed air in the mixing chamber 44 and is mixed with the air. Thereafter, the air-fuel mixture passes through the mixing promoting body 45, passes through the injection hole 39a, and flows from the injection nozzle 40a to the combustion chamber 40a. Supplied within 12. At the injection end timing, first, the fuel injection by the fuel injection valve 15 is stopped, and thereafter, the valve body 36 is raised by the valve operating mechanism 37, and the injection nozzle 40a is closed.

On the other hand, in the engine 1 of the present embodiment in which the above-described fuel injection operation is performed, in the low-speed rotation and low-load operation region such as the idling operation, the needle valve 26 of the combustion stabilization device 17 moves forward in the compression stroke. Open the suction hole 25a.
This allows the air in the cylinder to move from the pressure release hole 5c to the suction hole 25c.
a, it is sucked into the scavenging passage 3a via the suction passage 27, so that the fuel injected from the air fuel injection device 13 is drawn toward the pressure release hole 5c, that is, toward the electrode side of the ignition plug 16.

As described above, in the engine 1 of the present embodiment, by starting the fuel injection after the start of the injection of the compressed air, the fuel is injected into the air flow and the mixing chamber of the air flow and the fuel
Since 44 is provided in the vicinity of the injection nozzle 15b of the fuel injection valve 15, the injected fuel collides with the compressed air immediately after the injection and is mixed, so that the fuel is fined and the atomization is promoted. Further, in the present embodiment, since the mixing promoting body 45 is disposed in the mixing chamber 44, the atomization of the injected fuel can be promoted from this point as well.

Further, in the present embodiment, the fuel is injected with respect to the air flow and only during the period in which the air flow is flowing, so that all of the injected fuel flows into the combustion chamber 12 without fail. The accuracy of weighing is improved.

Furthermore, in this embodiment, in the low-speed rotation and low-load regions such as idling, the combustion stabilizing device 17 partially sucks the air in the cylinder to the electrode side of the ignition plug 16 during the compression stroke. Is attracted to the electrode side, ignition is ensured, and the combustion state is stabilized. In addition, the compression ratio will be substantially reduced by the depressurization,
Since the fuel injection amount can be increased while maintaining the idling rotation by that amount, the combustion state is also stabilized from this point. Here, since the sucked air contains unburned gas, if it is discharged into the exhaust pipe as it is, there is a problem in terms of exhaust gas countermeasures, but in this embodiment, the scavenging passage 3a
Such a problem does not occur.

〔The invention's effect〕

As described above, according to the air fuel injection device for a fuel injection engine according to the present invention, fuel is started after air injection is started, and air injection is ended after fuel injection is completed, so that fuel is converted into an air flow. On the other hand, the fuel is injected only during the period when the air is flowing, and the mixing chamber of the fuel and the air is provided in the immediate vicinity of the fuel injection nozzle, so that the atomization of the fuel can be promoted and the measurement accuracy of the injected fuel is improved. There is an effect that can be done.

[Brief description of the drawings]

FIG. 1 is a sectional side view of an air fuel injection device according to one embodiment of the present invention, and FIG. 2 is a fuel injection type 2 equipped with the embodiment device.
It is a sectional side view of a cycle engine. In the figure, 1 is an in-cylinder injection engine, 13 is an air fuel injection device, 14 is an air-fuel mixture injection valve (air injection mechanism), 15 is a fuel injection valve (fuel injection mechanism), 15b is a fuel injection nozzle, and 44 is a mixing chamber. It is.

Claims (1)

(57) [Claims] An in-cylinder injection engine having an air injection mechanism for injecting compressed air from an air injection nozzle and a fuel injection mechanism for injecting fuel from a fuel injection nozzle, wherein fuel is directly injected into a cylinder. In the air fuel injection device, a mixing chamber of air and fuel is formed so as to be located immediately adjacent to the fuel injection nozzle and larger in diameter than the fuel injection nozzle and the air injection nozzle. A nozzle is opened, and an orifice portion is formed between the mixing chamber and an injection nozzle which opens to a combustion chamber in a mixture passage following the mixing chamber, and after the air injection is started by the air injection mechanism, the fuel injection mechanism is started. A fuel injection device for a direct injection engine, characterized in that the fuel injection is started and the air injection is ended after the fuel injection is ended.