JPH0533739A - Assist air type fuel injector - Google Patents

Abstract

PURPOSE:To atomize injection fuel by means of assist air by forming a fuel injector of an inner-cylinder direct injection type with a simple structure and compactness. CONSTITUTION:An air chamber 36 is formed between an injection nozzle 31 and a cover 33. An assist air from the air chamber 36 is injected into a swirl chamber 37 in an tangential direction through air injection ports 35A, 35B. An injected fuel from an injection port 31A is under a turning condition, and directly injected into a cylinder of an engine from an injection port 35C. After injection of the fuel, the injection port 35C is blocked with a check valve 38 for preventing contraflow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assist air type fuel injector suitable for use in supplying fuel into a cylinder of an automobile engine in a state of being atomized by assist air.

[0002]

2. Description of the Related Art Generally, an electronically controlled fuel injection device mounted on an automobile or the like is a port injection type fuel injection device that injects fuel on the intake manifold side of the engine and mixes it with intake air to supply it into the cylinder of the engine. A fuel injector and an in-cylinder direct injection type fuel injector that directly injects fuel into a cylinder of an engine are used.

The in-cylinder direct injection type fuel injector is mounted on the cylinder head of the engine so that the tip side faces the inside of the cylinder of the engine, and the fuel supplied from the outside is directly injected into the cylinder of the engine from the tip side. Let

[0004]

By the way, in the in-cylinder direct injection type fuel injector according to the above-mentioned prior art, the valve body of the injector opens at the combustion pressure generated in the cylinder, and the combustion gas in the cylinder is generated. In order to prevent backflow into the injector, the injector is configured as an outward opening type injector.

Therefore, in the conventional technique, there is a problem that the seal structure and the valve structure of the fuel injector are complicated and the size of the entire injector is increased.

Further, it is difficult to uniformly mix the fuel directly injected from the fuel injector into the cylinder with the intake air in the cylinder, and there is a problem that the combustion stability cannot be improved.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention can prevent the valve structure and the like from becoming complicated, can be made compact as a whole, and can directly inject fuel into a cylinder. It is an object of the present invention to provide an assist air type fuel injector capable of promoting the atomization of the fuel and improving the combustion stability.

[0008]

The structure adopted by the present invention to solve the above-mentioned problems is an injector main body having a built-in electromagnetic actuator, and the injector main body is provided at the tip end side of the injector main body and is supplied into the injector main body. An injection nozzle for injecting the injected fuel from an injection port, and a valve element provided between the injection nozzle and the injector main body for opening and closing the injection port of the injection nozzle, and driven by an electromagnetic actuator in the injector main body And a bottomed cylindrical cover provided outside the injection nozzle to define an air chamber between the injection nozzle and an air inlet for introducing assist air from the outside into the air chamber. An air valve provided between an air introduction port of the cover and an assist air source, and a bottom of the cover so as to communicate with the injection port of the injection nozzle. A swirl chamber that is formed on the side of the cover and that allows the assist air in the air chamber to flow tangentially to give a swirl flow to the fuel from the injection port; It is composed of an ejection hole communicating with the outside and a check valve that allows the fuel in the swirl chamber to be ejected from the ejection hole toward the outside together with the assist air and blocks a reverse flow.

Further, it is preferable that the air valve is opened before the valve body is opened by the electromagnetic actuator, and is closed after the valve body is closed.

[0010]

With the above structure, even when used as a direct cylinder injection type fuel injector, the check valve can always close the injection hole, and the combustion gas from the cylinder is directed to the swirl chamber or the injection nozzle. Backflow can be prevented. Then, at the time of fuel injection, the check valve can be opened by the injection pressure or the like, and the fuel can be atomized by ejecting the fuel from the swirl chamber to the outside together with the assist air.

Further, if the air valve is opened before the valve body is opened and closed after the valve body is closed, the assist air can be stably supplied to the fuel injected from the injection nozzle into the swirl chamber. It can be applied, and the fuel can be surely atomized while giving a swirling flow to the fuel in the swirl chamber.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 4 by taking a fuel injection device provided with an assist air type fuel injector as an example.

In the figure, reference numeral 1 denotes an automobile engine body, which is, for example, a cylinder 2 of four cylinders.
(Only one cylinder is shown), a cylinder head 3 mounted on the cylinder 2, a piston 5 that reciprocates in the cylinder 2 and defines a combustion chamber 4 between the cylinder head 3 and the piston 5.
The cylinder 5 is roughly composed of a connecting rod 7 that connects the piston 5 to a crankshaft 6 and derives a reciprocating motion of the piston 5 as a rotational output of the crankshaft 6. An intake valve 8 and an exhaust valve 9 are provided in the cylinder head 3. It is provided.

Reference numeral 10 denotes an intake pipe connected to the intake side of the cylinder head 3. The intake pipe 10 is constructed to include an intake manifold and the like, and an air cleaner 11, an air flow meter 12, a throttle valve 13 and the like are provided in the middle thereof. It is provided. Reference numeral 14 denotes an exhaust pipe connected to the exhaust side of the cylinder head 3. The exhaust pipe 14 is configured to include an exhaust manifold and the like, and exhaust gas from the combustion chamber 4 is exhausted by an exhaust valve 9
It is discharged to the outside when the valve is opened.

Reference numeral 15 denotes a fuel tank provided in the rear part of the vehicle, and 16 denotes a fuel pump provided in the fuel tank 15. The fuel pump 16 feeds the fuel F in the fuel tank 15 into the supply pipe 17. It is discharged and injected from an injector 29, which will be described later, into the combustion chamber 4. Reference numeral 18 denotes a pressure regulator for adjusting the fuel pressure in the supply pipe 17, and the pressure regulator 18 guides the intake air pressure in the intake pipe 10 through the control pressure conduit 19 to adjust the fuel pressure to the intake air pressure. , The excess oil of the fuel F is returned to the piping 20
It returns to the inside of the fuel tank 15 via.

Reference numeral 21 denotes an air pump which serves as an assist air source. The air pump 21 is driven by the rotation of the crankshaft 6 via pulleys 22 and 23, a belt 24, and the like.
The intake air in the intake pipe 10 is sucked from the air conduit 25 side and discharged to the air conduit 26 side. The tip end side of the air conduit 26 is connected to an air inlet 34B of the injector 29, which will be described later, so that the intake air from the air pump 21 is supplied to the injector 29 as assist air.

Reference numeral 27 denotes a pressure regulator serving as a pressure control valve provided in the middle of the air conduit 26. The pressure regulator 27 has substantially the same structure as the pressure regulator 18, and the intake air pressure in the intake pipe 10 is controlled by the control pressure. Conduit 19
Guided through. Then, the pressure regulator 27 controls the air pressure of the assist air supplied to the injector 29 to a pressure slightly lower than the fuel pressure in the supply pipe 17, and the surplus assist air is removed from the air conduit 28 to one of the intake air. As a part, it is returned to the inside of the intake pipe 10.

Reference numeral 29 denotes an in-cylinder direct injection type injector as an assist air type fuel injector attached to the cylinder head 3 so as to face the inside of the combustion chamber 4.
As shown in FIG. 2, the injector 29 is an injector main body 30 incorporating an electromagnetic actuator (not shown).
And a cylindrical injection nozzle 31 provided on the tip side of the injector main body 30 for injecting the fuel F supplied from the fuel pump 16 into the injector main body 30 from the injection port 31A, and a valve seat of the injection nozzle 31. 31B is slidably inserted into the injection nozzle 31 so as to be separated from and seated on the injection nozzle 31B, and is driven by an electromagnetic actuator in the injector main body 30 to open and close the injection port 31A of the injection nozzle 31. The needle valve 32 and the needle valve 32 are included.

Reference numeral 33 denotes a bottomed cylindrical cover which covers the periphery of the injection nozzle 31 and constitutes a part of the injector 29. As shown in FIG. 2, the cover 33 is a caulking portion 34A on the upper end side of the injector main body 30. And a lid 35 screwed to the inner periphery of the lower end side of the injection nozzle 31 at the tip end side of the injection nozzle 31, and is fixed to the injection nozzle 31. An air chamber 36 is defined between them. Further, an air inlet 34B extending obliquely upward is formed on the upper side of the cylindrical body 34, and the tip end side of the air conduit 26 is connected to the air inlet 34B. The assist air from the air conduit 26 is supplied to the air valve 42 described later.
When the valve is opened, the air is supplied into the air chamber 36, and a swirl (swirl flow) is given to the injected fuel in a swirl chamber 37 described later.

On the other hand, the cover 35 of the cover 33 is formed so as to cover the tip end surface of the injection nozzle 31, and a swirl chamber 37 having a stepped shape is formed on the inner peripheral side thereof.
Further, two sets of air ejection holes 35A, 35A, ..., 35 that extend in the tangential direction of the swirl chamber 37 in the lid 35 and communicate the inside of the swirl chamber 37 with the inside of the air chamber 36.
B, 35B, ... Are formed so as to be spaced apart from each other on the upper and lower sides, and the respective air ejection holes 35A, 35B are oriented in a direction perpendicular to each other so as to form a set of four as illustrated in FIG. The lid 35 is located below the swirl chamber 37, and the swirl chamber 37 is provided in the combustion chamber 4 of the engine body 1.
An ejection hole 35C communicating with the ejection hole 35C is formed.
Causes the fuel, which is injected from the injection port 31A and is swirled by the assist air in the swirl chamber 37, to be ejected into the combustion chamber 4 together with the assist air.

Reference numeral 38 denotes a check valve provided in the lid 35 to open and close the ejection hole 35C of the lid 35. The check valve 38
Is fixed to the valve shaft 39A of the valve body 39 in the swirl chamber 37, which is an outward-opening type valve body that is separated from and seats on the valve seat 35D formed on the outer surface of the lid body 35, and the injection nozzle 31
Spring receiver 40 arranged below the injection port 31A of the
In order to constantly urge valve 9 in the valve closing direction, swirl chamber 37
It comprises a spring 41 disposed between the step portion 35E of the lid 35 and the spring receiver 40, and the spring 41 is easily compressed by the injection pressure of the fuel injected from the injection port 31A. When the fuel is injected, the check valve 38 causes the fuel in the swirl chamber 37 to be ejected into the combustion chamber 4 through the ejection holes 35C together with the assist air, so that the combustion gas or the like from the combustion chamber 4 is ejected into the swirl chamber 37. Prevent backflow.

Further, 42 is an air introduction port 34 of the cylindrical body 34.
Located between B and the pressure regulator 27, the air conduit 2
6 shows an air valve provided in the middle of 6, and the air valve 42 is opened by exciting a solenoid 42A and is normally closed by a spring 42B as shown in FIG. The air valve 42 is opened by a control signal from the outside as shown in FIG. 4 before the needle valve 32 is opened, and is closed after the needle valve 32 is closed.

The fuel injection system according to this embodiment has the above-mentioned construction, and its operation will be described below.

First, in the engine body 1, the piston 5 reaches the top dead center at time t1 as shown by the characteristic line in FIG.
Then, the intake stroke is performed until the bottom dead center is reached. At this time, the intake valve 8 opens and intake air is sucked into the combustion chamber 4 from the intake pipe 10. Then, in the middle of the intake stroke, first, the air valve 42 is opened to supply the assist air from the air pump 21 into the air chamber 36, and the needle valve 32 is opened with a time delay Δt1 of, for example, about several ms to open the fuel pump. The fuel F from 16 is injected into the swirl chamber 37.

Next, after the piston 5 reaches the bottom dead center at the time t2, the compression stroke is performed until it reaches the top dead center at the time t3. In the middle of the compression stroke, the needle valve 32 is first closed. State, and then a time delay Δt of about several ms
2, the air valve 42 is closed, and the fuel directly injected with the assist air into the combustion chamber 4 is compressed by the piston 5 while being mixed with the intake air. Then, before the piston 5 reaches the top dead center at the time t3, the air-fuel mixture in the combustion chamber 4 is ignited with a predetermined advance angle, and the expansion stroke is performed until the piston 5 reaches the bottom dead center at the time t4. Become. Further, the exhaust valve 9 is opened before reaching the time point t4, and
From 4 to the time t5, the exhaust stroke is performed until the piston 5 reaches the top dead center, and the engine body 1 sequentially repeats the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke to derive the rotation output from the crankshaft 6. Let

The assist air supplied into the air chamber 36 by opening the air valve 42 as described above is tangentially ejected into the swirl chamber 37 from the air ejection holes 35A and 35B formed in the lid 35. While giving a swirl flow to the fuel injected from the ejection port 31A in the swirl chamber 37, the injected fuel is directly ejected from the ejection hole 35C into the combustion chamber 4 together with the assist air in a swirled state. At this time, the check valve 38 separates the valve body 39 from the valve seat 35D by the fuel injection pressure or the like, and allows the injected fuel to be ejected into the combustion chamber 4 in the state of being atomized by the assist air.

The opening time of the air valve 42 is delayed by the time Δt1 and Δt2 from the opening time of the needle valve 32.
The swirl chamber 37 is set longer than
In the inside, fuel is injected in a state where the assist air is constantly ejected, and this injected fuel flows from the ejection hole 35C to the combustion chamber 4 in a state where atomization is promoted by the assist air in the swirl chamber 37. It is possible to effectively prevent the fuel from being jetted and staying in the swirl chamber 37 in the form of liquid droplets.

After the air valve 42 is closed, the pressure in the swirl chamber 37 decreases, so that the valve element 39 of the check valve 38 is seated on the valve seat 35D by the spring 41 and closes the ejection hole 35C. As a result, it is possible to prevent the combustion gas and the like in the combustion chamber 4 from flowing back toward the swirl chamber 37 in the latter half of the compression stroke and the expansion stroke, so that the injection port 31A and the air ejection holes 35A due to impurities and the like in the combustion gas. , 35B
It can solve problems such as being blocked.

Therefore, according to the present embodiment, the injection nozzle 31 is provided on the tip side of the injector main body 30 and the needle valve 32 is driven in the injection nozzle 31 to inject the fuel from the injection port 31A. The port injection type fuel injector is provided with the cover 33 to provide the air chamber 36.
And a swirl chamber 37 and the like, and a check valve 38 that opens and closes the swirl chamber 37 with respect to the combustion chamber 4 can be provided to configure an in-cylinder direct injection type assist air fuel injector 29. The structure of the injector 29 can be greatly simplified and made compact, and atomization of the fuel can be promoted by the assist air, and this fuel can be uniformly mixed with the intake air in the combustion chamber 4.

Further, since the air valve 42 is opened earlier than the needle valve 32 and is closed with a predetermined time delay Δt2 after the needle valve 32 is closed, the air valve 42 is always assisted during fuel injection in the swirl chamber 37. The air can be continuously applied, the atomization of the fuel can be effectively promoted, and the fuel can be prevented from staying in the form of droplets on the stepped portion 35E of the lid 35 or the like. It is possible to achieve various effects such as reliably improving combustion stability by eliminating the above.

In the above-mentioned embodiment, the needle valve 32 has been described as being opened with a predetermined valve opening time as shown by the characteristic line in FIG. 4, but the needle valve 32 is actually intermittent by the injection pulse. The valve is repeatedly opened and closed for a predetermined time, and the air valve 42 may be similarly opened and closed.

[0032]

As described in detail above, according to the present invention, a bottomed cylindrical cover is provided outside the injection nozzle, and a swirl chamber into which assist air flows in the tangential direction is formed on the bottom side of the cover. While the fuel is swirling in the swirl chamber, the fuel is ejected to the outside from the ejection hole, and the check valve is provided in the ejection hole. Therefore, the cylinder direct injection type assist air fuel injector is simple. With such a structure, it can be formed compactly and can be miniaturized. Further, atomization of the fuel directly injected into the cylinder can be effectively promoted, and combustion stability can be improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a fuel injection device according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of an essential part showing an injector of FIG. 1 in an enlarged manner.

FIG. 3 is an enlarged sectional view taken along the line III-III in FIG.

FIG. 4 is a characteristic diagram showing opening / closing characteristics of an intake valve, an exhaust valve, an air valve and a needle valve.

[Explanation of symbols]

1 engine body 2 cylinders 3 cylinder head 4 Combustion chamber 5 pistons 10 Intake pipe 15 Fuel tank 16 Fuel pump 21 Air pump (assist air source) 29 injectors 30 injector body 31 injection nozzle 31A injection port 32 Needle valve (valve body) 33 cover 34B air inlet 35A, 35B Air ejection holes 35C spout hole 36 Air chamber 37 Swirl chamber 38 Check valve 42 Air valve

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Kiyomura             Gunma Prefecture Isesaki City Kasukawa Town 1671-1 Nidec             Child Equipment Co., Ltd.

Claims (2)

[Claims] 1. An injector main body having an electromagnetic actuator built therein, and an injector main body provided at a front end side of the injector main body.
An injection nozzle for injecting fuel supplied into the injector body from an injection port, and an electromagnetic actuator provided in the injector body for opening and closing the injection port of the injection nozzle, the electromagnetic actuator being provided between the injection nozzle and the injector body. A valve body driven by the injection nozzle and the injection nozzle so as to define an air chamber between the injection nozzle and an air inlet for introducing assist air from the outside into the air chamber. A bottom cylindrical cover, an air valve provided between an air introduction port of the cover and an assist air source, and a bottom portion of the cover so as to communicate with the injection port of the injection nozzle, and the air chamber. Assist air is introduced tangentially into the swirl chamber to give a swirl flow to the fuel from the injection port, and the swirl chamber is provided at the bottom side of the cover. Of the swirl chamber and a check valve that allows the fuel in the swirl chamber to be ejected from the spout hole toward the outside together with the assist air and blocks a reverse flow. Assisted air fuel injector. 2. The assist air type fuel injector according to claim 1, wherein the air valve is configured to be opened before the valve body is opened by the electromagnetic actuator and closed after the valve body is closed. .