JPH04101059A - Assist air type fuel injector - Google Patents

Abstract

PURPOSE:To prevent the generation of wall membrane flow effectively while atomizing injected fuel by jetting supercharged assist air from each air jetting nozzle toward fuel jetted from an jetting nozzle so as to collide with jetted fuel diagonally from the right and left sides, thereby dividing jetted fuel longitudinally into two. CONSTITUTION:This injector 11 is provided with an injector body 12, that is, a stepped cylindrical body, a valve body 13 with an injection nozzle 13A and a valve seat 13B formed at its bottom part center provided in line with the tip side of the injector body 12, and a needle valve 14 driven by an electromagnetic actuator so as to open/close the injection nozzle 13A. A cover 16 is further provided to partition an air chamber 17 between the cover 16 and the valve body 13. At the center of the bottom part 16A of the cover 16, an jetting nozzle 19 bored coaxially with the injection nozzle 13A and a spray nozzle 15B is formed as a tapered hole expanded gradually downward. Also on the inner peripheral surface side of tapered protruding parts 20 formed integrally on the outer peripheral side of the bottom part 16A, a pair of air exhaust nozzles 21, 21 are bored downward with the same inclination in laterally symmetrical positions to the jetting nozzle 19.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is suitable for use in, for example, 4-valve engines of automobiles, and is an assist air type that can promote atomization of injected fuel by supercharging assist air. Regarding fuel injectors.

[Conventional technology]

Generally, in a four-valve engine, each cylinder of the engine is provided with two intake valves and two exhaust valves, respectively, in the cylinder head.

Therefore, FIGS. 4 and 5 show a fuel injection device for a four-valve engine according to this type of prior art.

In the figure, reference numeral 1 indicates an engine main body (only the part corresponding to one cylinder of a multi-cylinder engine is shown), and the engine main body l has a cylinder head I on a cylinder (not shown).
A is mounted, and inside the cylinder head IA are two intake boats and two exhaust boats (none of which are shown) that communicate with the inside of the cylinder, and two ports that open and close each intake boat.
Two intake valves 2, 2 and two exhaust valves 3, 3 for opening and closing each exhaust boat are provided.

Reference numeral 4 indicates an intake pipe consisting of an intake manifold, etc., and the tip side of the intake pipe 4 is provided with, for example, two branch pipes 4A, 4A, and the tip of each branch pipe 4A is connected to each intake boat of the cylinder head IA. It is connected to the. The intake pipe 4 has an injector mounting portion 4 on the opposite side of each branch pipe 4A.
B (hereinafter referred to as attachment part 4B) is provided, and the attachment part 4
A fuel injector 6, which will be described later, is attached to B. In addition, a throttle valve (
(not shown) is provided to adjust the amount of intake air sucked into the cylinder according to the amount of depression of an accelerator pedal (not shown). Further, 5 indicates an exhaust pipe consisting of an exhaust manifold and the like connected to the exhaust boat of the cylinder head IA.

Reference numeral 6 indicates a fuel injector as a fuel injection valve attached to the attachment part 4B of the intake pipe 4 via a fixing member 7, etc., and the fuel injector 6 includes an injector body 6A containing an electromagnetic actuator, etc., and an injector body 6A. It consists of a valve body 6B provided on the tip side of the valve body 6A, and a valve body 6D (see FIG. 5), which is actuated by the electromagnetic actuator and is a needle valve or the like that opens and closes the injection port 6C of the valve body 6B. A bottle 6E is integrally formed at the protruding end of the valve body 6D. and,
The fuel injector 6 is a fuel pump (not shown)
The fuel supplied under pressure is injected from the injection port 6C.

In the conventional technology configured as described above, when an injection pulse is applied from the outside to the electromagnetic actuator in the injector body 6A, the valve body 6D is opened by the electromagnetic actuator as shown in FIG. Mouth 6
Fuel is injected and supplied from C into each branch pipe 4A. In this case, since a bottle 6E is provided at the tip of the valve body 6D, the fuel from the injection port 6C collides with the bottle 6E, is atomized into fine particles, and is ejected as shown in the figure. Then, this injected fuel mixes with the intake air in the intake pipe 4, becomes an air-fuel mixture, is sucked into the cylinder of the engine body 1, burns in this cylinder, and then becomes exhaust gas and enters the exhaust pipe 5. It is sequentially discharged to the outside.

[Problem to be solved by the invention]

However, in the above-mentioned conventional technology, the injected fuel from the injection port 6C is only atomized by colliding with the bottle 6E, and most of the injected fuel adheres to the wall surface 40 of the intake pipe 4 and forms a liquid wall. This results in a film flow, which has the drawback of lowering combustion efficiency and increasing the HC concentration in the exhaust gas.

In addition, as shown in FIG. 6, a separator 8 is attached to the tip of the valve body 6B, and the injected fuel is divided into two directions and ejected from two injection holes 8A, 8A formed in the separator 8. Other conventional techniques are also known in which fuel is prevented from adhering to the wall surface 4C of the intake pipe 4. However, in this case, the fuel is ejected in liquid form from each ejection hole 8A of the separator 8. In addition to poor fuel atomization and mixing properties, this ejected fuel adheres to the valve body of the intake valve 2 and forms a liquid film, and when the intake valve 2 is opened, large particle size particles enter the cylinder. This has the disadvantage that it is sucked in and adheres to the cylinder wall surface as a thick liquid film, increasing the flame-extinguishing area within the cylinder and increasing the FiC concentration in the exhaust gas.

Furthermore, as another conventional technique, there is also known an assist air type fuel injector that promotes atomization of the injected fuel by supplying supercharging assist air to the injected fuel. However, this type of assist air type fuel injector only atomizes the injected fuel, and when used in, for example, a 4-valve engine, the injected fuel cannot be divided into two directions. There is a drawback that fuel may adhere to and stagnate on the wall surface 40 of the intake pipe 4 shown in FIG. 4, etc., thereby forming a liquid wall flow.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and the present invention effectively prevents the generation of wall film flow by atomizing the injected fuel and dividing it into two parts. The purpose of the present invention is to provide an assist air type fuel injector that not only improves efficiency and exhaust gas characteristics but also has a compact overall structure, is small and lightweight, and has a rigid structure.

[Means for Solving the Problems J] In order to solve the above-mentioned problems, the present invention includes an injector body to which fuel is supplied from the outside, and an injector body provided at the tip side of the injector body to inject the fuel inside the injector body. A valve body for defining an air chamber between a valve body for injecting from the mouth, a dipping valve body driven by an actuator provided in the injector body to open and close the injection port of the valve body, and the valve body. A cylindrical cover with a bottom is provided on the outside of the valve body and is formed with an air inlet for introducing supercharging assist air into the air chamber from the outside; an ejection port for ejecting fuel injected from the port toward the outside together with the supercharging assist air in the air chamber; and a left side from the ejection port.

The supercharged assist air in the air chamber is obliquely formed on the bottom of the cover and spaced apart to the right, and collides obliquely from the left and right with the fuel ejected from the jet port together with the supercharged assist air. A configuration is adopted that includes a pair of air injection holes that divide the ejected fuel into two parts in the front-rear direction.

The cover includes an inner cylindrical body that defines an inner air chamber between the cover and the valve body, and an outer cylindrical body that defines an outer air chamber between the inner cylindrical body and the inner cylindrical body. The outlet may be communicated with the inner air chamber, and each of the air jet holes may be communicated with the outer air chamber.

[Effect]

With the above configuration, the supercharging assist air from each air nozzle and the fuel jetted from the nozzle are directed diagonally to the left.

By colliding from the right, the jetted fuel can be divided into two parts in the front and rear directions, and for example, the jetted fuel can be efficiently supplied to each intake boat of a four-valve engine.

In addition, if the air chamber is separated into an inner air chamber and an outer air chamber, and higher pressure supercharging assist air is ejected from the outer air chamber through each air ejection hole, the fuel ejected from the ejection port can be reduced. It can be divided into two parts more reliably.

【Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3. In this embodiment, the same components as those of the prior art shown in FIG. 4 described above are given the same reference numerals, and their explanations will be omitted.

Thus, FIGS. 1 and 2 show a first embodiment of the present invention.

In the figure, reference numeral 11 indicates an assist air type fuel injector that is attached to the attachment part 4B of the intake pipe 4 via the fixing member 7, etc. The injector 11 is formed in a stepped cylindrical shape, and has an annular flange on the outer circumferential side. 12A, and a valve body 13, which is provided on the injector body 12 so as to protrude downward from the tip side of the injector body 12, and has an injection port 13A and a valve seat 13B formed in the center of the bottom. , the injection port 1 of the valve body 13
3A, a needle valve 14 as a valve body which is movably provided within the valve body 13 and driven by an electromagnetic actuator (not shown) provided within the injector main body 12, and a cover 16 to be described later. The injection port 13 of the valve body 13 is located at the tip of the needle valve 14.
A small-diameter protrusion 14A is formed that protrudes downward through A.

Further, a protector 15 is fixed to the distal end surface of the valve body 13, and a needle valve 1 is attached to the inner peripheral side of the protector 15.
A small diameter cylindrical portion 15A that protrudes downward is provided to protect the protrusion 14A of No. 4 and to promote atomization of fuel by supercharging assist air, which will be described later. A small-diameter spray port 15B communicating with the injection port 13A is formed at the tip of the small-diameter cylindrical portion 15A, and the spray port 15B transfers fuel injected from the injection port 13A to the needle valve 14 when the needle valve 14 is opened. The liquid is sprayed to the outside in a predetermined spray pattern via between the projection 14A and the small diameter cylindrical portion 15A. Also,
The outer peripheral side of the tip of the small diameter cylindrical portion 15A becomes a tapered surface 15C,
Supercharging assist air, which will be described later, is led out in the direction of arrow A in FIG.

Reference numeral 16 indicates a cover defining an air chamber 17 between it and the valve body 13, and the cover 16 has a bottom portion 16A and a cylindrical portion 16B.
The cylindrical portion 16B is formed into a cylindrical shape with a stepped bottom, and a caulking portion 16C that is caulked and fixed to the flange portion 12A of the injector body 12 is provided on the upper end side of the cylindrical portion 16B. The cover 16 is fixed to the injector main body 12 via a caulked portion 16C so as to surround the valve body 13, and a part of the air chamber 17 is formed between the bottom portion 16A of the cover 16 and the protector 15. A gap of a predetermined size is formed. Further, an air introduction port 16D is provided in the cylindrical portion 16B of the cover 16 in a radial direction and inclined upward for introducing supercharging assist air at a predetermined pressure into the air chamber 17 from the outside. 16D is connected via an air conduit 18 to a source of pressurized air (not shown).

19 has an injection port 13A in the center of the bottom 16A of the cover 16;
A nozzle 19 is shown coaxially with the nozzle 15B, and the nozzle 19 is formed as a tapered hole that gradually expands downward in the axial direction of the bottom 16A.
The fuel injected from A through the spray nozzle 15B is ejected to the outside, and the supercharging assist air in the air chamber 17 is led out in the direction of arrow A.

Reference numeral 20 indicates a tapered protrusion that is radially spaced apart from the spout 19 of the cover 16 and integrally formed on the outer peripheral side of the bottom 16A, and the inner peripheral surface of the protrusion 20 is radially outward from the bottom 16A. , and expands downward at a predetermined angle of inclination, and has a conical shape so as to surround the fuel jetted from the jet port 19 together with the supercharging assist air from the outside in the radial direction. Also,
A pair of air ejection holes 21.21 are bored on the inner peripheral surface side of the protrusion 20 at positions symmetrical to the left and right with respect to the ejection port 19, and each air ejection hole 21 has the same downward slope. It is elongated with corners and has a relatively small diameter. Each of the air jet holes 21 jets out the supercharged assist air in the air chamber 17 at a high flow velocity in the direction of arrow B, and directs the jetted supercharged assist air diagonally toward the fuel F jetted from the jet nozzle 19. By colliding from the left and right, this injected fuel F is divided into two in the front and back direction as shown in FIG.

The assist air type fuel injector 11 according to this embodiment has the above-mentioned configuration, and its operation will be explained next.

First, when supercharging assist air at a predetermined pressure is supplied from a pressure source into the air chamber 17 through the air conduit 18, this supercharging assist air is ejected from the ejection port 19 of the cover 16 in the direction of arrow A, and A portion of the air is ejected from each air ejection hole 21 in the direction of arrow B in the form of a high-speed jet.

Further, when an injection pulse is applied from the outside to the electromagnetic actuator inside the injector body 12, the needle valve 14 repeatedly opens and closes, and the fuel supplied from the outside into the injector body 12 is transferred from the injection port 13A of the valve body 13 to the rotifer. 15 spray ports 15B, the cover 1
6 along with the supercharging assist air from the jet port 19 shown by the arrow A.
Spout in the direction. At this time, this ejected fuel F is
When injected from 5B, it is atomized by colliding with the supercharged assist air in the direction of arrow A, and its particle size becomes smaller (becomes) and atomization is promoted.

After this atomized jetted fuel F is jetted out from the jetting port 19, the supercharging assist air jetted out from each air jetting hole 21 in the direction of arrow B diagonally downward from the left and right. Due to the collision, the state of the jetted fuel F shown by the solid line in FIG.
, F+ state, for example, the injected fuel F is divided in the front and back direction, and each injected fuel F is gradually given an independent injection force, and as shown in FIG. .

Afterwards, it becomes a spray pattern divided into two parts and is ejected in a mist form.
This further promotes atomization.

Thus, according to this embodiment, the fuel injected from the injection port 13A of the valve body 13 through the spray port 15B is ejected from the injection port 19 to the outside together with the supercharging assist air in the air chamber 17. In addition to being able to atomize the injected fuel F, this injected fuel F can be split into two injected fuels F, , F by colliding with the supercharging assist air from each air injection hole 21, so that the fuel injector 11 can be
Attachment part 4B of intake pipe 4 instead of injector 6 shown in the figure
By attaching each injected fuel F+ to each branch pipe 4A
can be supplied in an atomized state into the cylinders of the engine main body L through the fuel pump, which can improve the atomization mixing property with the intake air and improve the combustion efficiency. It is possible to effectively prevent the adhesion and formation of a wall film flow, and it is possible to reliably reduce harmful components in the exhaust gas.

Further, since the fuel injector 11 can jet the supercharging assist air in a jet form from each air jet hole 21 formed on the cover 16 and divide the jetted fuel F into two, for example, the assist air type fuel described in the prior art can be used. A single injector 11 can provide substantially the same effect as when two injectors are provided, and the overall structure can be significantly simplified to achieve a reduction in size and weight, and various other effects are achieved.

Next, FIG. 3 shows a second embodiment of the present invention. In this embodiment, the same components as those in the first embodiment are given the same reference numerals, and their explanations will be omitted. The feature of this embodiment is that the cover 31 provided on the outside of the valve body 13 is
An inner cylindrical body 32 formed into a stepped cylindrical shape, and an outer cylindrical body 33 located outside the inner cylindrical body 32 and formed into a stepped bottomed cylindrical shape from a bottom portion 33A and a cylindrical portion 33B. An inner air chamber 34 is defined between the inner cylindrical body 32 and the valve body I3, and an outer air chamber 35 is defined between the inner cylindrical body 32 and the outer cylindrical body 33.

Here, the outer cylindrical body 33 surrounds the valve body 13 together with the inner cylindrical body 32, and a caulked portion (not shown) on the upper end thereof is fixed to the flange 12A (see FIG. 1) of the injector main body 12. , the inner cylindrical body 32 is connected to the valve body 1
It is positioned around 3. Further, an air introduction port 32A is formed on the upper side of the inner cylinder 32.
2A is connected to an air source (not shown) at a predetermined pressure via an air conduit 18 extending through the outer cylindrical body 33. The air inlet 32A introduces supercharged assist air from a pressurized air source into the inner air chamber 34, and the air in this air chamber 34 is led out from the jet port 19 in the direction of arrow A. .

In addition, other air introduction 03 is provided to the cylindrical portion 33B of the outer cylindrical body 33.
3C is formed, and the air inlet 33G is connected to another pressurized air source (
(not shown). Then, the air conduit 33
C introduces supercharging assist air having a higher pressure than the inner air chamber 34 into the outer air chamber 35, and blows out this air from the outer air chamber 35 through each air jet hole 21 in the direction of arrow B. ing.

Thus, in this embodiment configured in this way, it is possible to obtain substantially the same effects as in the first embodiment, but in particular, in this embodiment, the inner air chamber 3 is provided in the outer air chamber 35.
Since supercharging assist air with a higher pressure than 4 is introduced and this air is blown out from each air outlet 21 in the direction of arrow B, the flow velocity of the air blown out in the direction of arrow B can be effectively increased. , this air can be made to collide with the jetted fuel F,
The ejected fuel F can be reliably divided into two ejected fuels F,,F.

In addition, in each of the above embodiments, the bottom part 1 of the cover 16 (31)
6A (33A), the protrusion 20 is formed in a tapered shape, but the protrusion 20 is formed on the bottom 16A (33A).
A) It does not necessarily have to be formed on the outer periphery of the lower surface over the entire circumference; for example, a pair of protrusions may be provided at positions spaced apart to the left and right from the ejection port 19, and an air ejection hole 21 may be formed in each of the protrusions. It may also be formed.

[Effects of the Invention] As detailed above, according to the present invention, an air chamber is defined between the valve body and the cover, and the supercharging assist air is injected together with the fuel from the injection port in the air chamber. Since the injected fuel is split into two parts by colliding supercharging assist air with the injected fuel, for example, the two parts of the injected fuel can be supplied to each intake boat of a 4-valve engine in an atomized state, and combustion within the cylinders is possible. In addition to improving efficiency, the generation of wall film flow can be effectively prevented, and exhaust gas characteristics can be improved.

Furthermore, if the air chamber is separated into an inner air chamber and an outer air chamber, and higher pressure air is ejected from the outer air chamber through each air outlet, the ejected fuel can be divided into two parts more reliably. This makes it possible to achieve various effects such as being able to more reliably prevent the occurrence of wall flow.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the present invention. FIG. 1 is an enlarged vertical cross-sectional view of the main part of an assist air type fuel injector, and FIG. An explanatory diagram showing different states of division, FIG. 3 is a vertical cross-sectional view similar to the first one showing the second embodiment, FIGS. 4 and 5 show the prior art, and FIG. 4 shows a fuel injection device. FIG. 5 is a longitudinal sectional view of the essential parts of the injector, and FIG. 6 is a longitudinal sectional view similar to FIG. 5 showing another prior art. 1...Engine body, IA...Cylinder head, 4
...Intake pipe, 4B...Injector mounting part, 11.
・・Assist air type fuel injector, 12・・
・Injector body, 13... Valve body, 13A
... Injection port, 14... Needle valve (valve body), 16.
31... Cover 16D, 32A, 33C... Air inlet, 17, 34. 35... Air chamber, 19... Air outlet, 21... Air outlet, 32... Inner cylinder body ,3
3... Outer cylinder, F, F,... Injected fuel. Figure 1

Claims (2)

[Claims] (1) An injector body to which fuel is supplied from the outside,
A valve body that is provided on the tip side of the injector body and injects the fuel in the injector body from the injection port, and is driven by an actuator provided in the injector body to open and close the injection port of the valve body. A bottomed cylindrical shape provided on the outside of the valve body to define an air chamber between the valve body and the valve body, and formed with an air inlet for introducing supercharging assist air into the air chamber from the outside. a cover, an ejection port formed at the center of the bottom of the cover for ejecting the fuel injected from the injection port of the valve body toward the outside together with the supercharging assist air in the air chamber; The supercharged assist air in the air chamber is obliquely formed on the bottom of the cover at a distance to the right, and collides diagonally from the left and right with the supercharged assist air in the air chamber toward the fuel ejected from the jet port together with the supercharged assist air.
The assist air type fuel injector is composed of a pair of air injection holes that divide the ejected fuel into two parts in the front and rear directions. (2) The cover includes an inner cylindrical body that defines an inner air chamber between the cover and the valve body, and an outer cylindrical body that defines an outer air chamber between the inner cylindrical body and the inner cylindrical body. The assist air type fuel injector according to claim (1), wherein the ejection port is communicated with an inner air chamber, and each of the air ejection holes is communicated with an outer air chamber.