JP2011157955A - Air blast injector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air blast injector achieving atomization in the initial time of injection, promoting mixing property of pressurized air and a liquid fuel by improving the shearing ability, and improved in the sucking speed by raising the sucking ability. <P>SOLUTION: A second needle 9 is provided with a center hole 11, to which the liquid fuel is to be supplied, and an air flow passage 12, in which the pressurized air flows, is provided between the second needle 9 and a second nozzle body 8, and a venturi part 13 is provided on the way of the air flow passage 12. A pore 15 as a fuel outlet for sucking the liquid fuel is opened in a region, in which the flow speed exceeds Mach 1 (the sound speed) after passing through the venturi part 13. The liquid fuel sucked through the pore 15 is raised in the shearing ability by the pressurized air of the flow speed, which exceeds Mach 1, to promote the mixing property with the pressurized air, and the fuel atomized in the initial time of injection is injected into a cylinder from a second injection hole 7. A region, in which the pore 15 as the fuel outlet is provided, is raised in the sucking ability by the negative pressure to be generated with enlargement of the diameter. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention includes a first injector that injects pressurized liquid fuel, and a second injector that injects pressurized air supplied from the outside together with the liquid fuel injected from the first injector. The present invention relates to an air blast injector.

In a fuel injection device mounted on an engine (an internal combustion engine that generates rotational torque by the combustion energy of fuel), a technique for atomizing liquid fuel and injecting it from an injector is desired for the purpose of improving fuel consumption and reducing emissions.
An air blast injector is known as an injector for achieving atomization of liquid fuel. The air blast injector is a composite injector composed of a first injector that injects liquid fuel and a second injector that injects liquid fuel injected from the first injector and pressurized air together. When the air passes through the second injection hole (injection hole of the second injector), the speed of sound is increased so that the liquid fuel injected together with the pressurized air is atomized.

  The prior art of an air blast injector is demonstrated with reference to FIG. 8 (for example, refer patent document 1). In addition, the code | symbol used in background art attaches | subjects the same code | symbol with respect to the same function thing as [the form for inventing] and [Example] mentioned later.

The first injection hole 3 (fuel injection hole) of the first injector 1 is disposed opposite to the upper end of the center hole 11 provided in the second needle 9 of the second injector 2, and the first injection hole 3 is the center hole. The fuel is injected toward the upper end of 11.
On the other hand, in the space where the first injection hole 3 of the first injector 1 injects fuel (the lower space of the first injector 1), air pressurized from the outside via the air introduction passage 43 (pressurized by an air pump). Air) is supplied.
Thus, the injected fuel is supplied from the first injector 1 to the upper portion of the second injector 2 and pressurized air is supplied via the air introduction passage 43.

The fuel injected and supplied from the first injector 1 to the upper portion of the second injector 2 mainly passes through the center hole 11 and passes through the thick hole J1 formed on the lower side surface of the second needle 9 from the lower end of the center hole 11. Thus, it collects at the lower end of the air flow path 12.
And if the 2nd injection hole 7 opens, the liquid fuel collected at the lower end of the air flow path 12 will be pushed out and injected by pressurized air.
As a result, at the initial opening of the second injection hole 7 (initial injection), the liquid fuel collected at the lower end of the air flow path 12 is pushed out from the second injection hole 7 in a collective state, and the injection is performed. The initial spray particle size becomes large.

Therefore, as a means for reducing the spray particle size at the initial stage of injection, the technique shown in FIG.
The technique shown in FIG. 9 is provided with a venturi portion 13 that restricts the flow area of the pressurized air in the middle of the air flow passage 12 and a pore 15 that leads from the lower end of the center hole 11 to the venturi portion 13. The liquid fuel in the center hole 11 is sucked into the pressurized air passing through the venturi section 13 by the venturi effect (ejector effect).
Specifically, when the second injection hole 7 is opened, the liquid fuel is sucked into the pressurized air that passes through the venturi portion 13. As a result, the pressurized air that has sucked fuel in the venturi section 13 is injected from the second injection hole 7 from the beginning of injection. For this reason, the spray particle diameter can be atomized from the initial stage of injection of the second injector 2.

(Problem 1)
Here, in the reference example shown in FIG. 9, the fuel outlet of the pore 15 is opened in the middle of the venturi portion 13 for the purpose of obtaining the venturi effect.
However, when the flow velocity analysis of the pressurized air passing through the venturi portion 13 was performed {see FIG. 2A}, it was found that the fastest part of the passage speed of the pressurized air was not passing through the venturi portion 13. .
For this reason, the liquid fuel sucked out from the pores 15 has low shearing ability for the pressurized air passing through the venturi section 13 to shear, and there is room for improvement in the mixing property between the pressurized air and the liquid fuel.

(Problem 2)
Further, when the pressure analysis of the pressurized air in the vicinity of the venturi portion 13 was performed {see FIG. 2 (b)}, the venturi portion 13 is a portion where the pressurized air passes through a narrow flow path even if the flow velocity is high. Therefore, a large pressure drop was not obtained.
For this reason, the suction capacity of the pore 15 to suck out the liquid fuel in the center hole 11 is low, and the fuel suction speed is slow.
If the diameter of the pore 15 is increased in order to increase the suction capacity, the liquid fuel leaks from the pore 15 before the second injection hole 7 is opened, and the fine particles at the initial stage of injection of the second injector. It will not be possible to achieve.

JP 10-325383 A

The present invention has been made in view of the above problems, and the object thereof is an air blast injector that achieves atomization at the initial stage of injection of the second injector using the Venturi effect.
(I) enhance the shearing ability of the pressurized air to shear the liquid fuel sucked out from the pores to promote the mixing of the pressurized air and the liquid fuel;
(Ii) To improve the sucking speed by increasing the sucking ability of the fine holes to suck out the liquid fuel in the center hole.

[Means of claim 1]
The air blast injector of claim 1 achieves atomization at the initial stage of injection of the second injector using the venturi effect, and has the following effects.
When the second injection hole is opened, the pressurized air in the air passage that flows toward the second injection hole is throttled by a venturi portion provided in the middle of the air passage.
The flow rate of the pressurized air passing through the venturi section increases due to fluid compression by the venturi section. For example, the passage speed reaches Mach 1 (sonic speed) or a flow speed close to Mach 1.

In this way, the flow velocity increases during the passage of the venturi section, and, for example, pressurized air that has reached a flow velocity close to Mach 1 or Mach 1 is fluidized in a region where the flow area on the downstream side of the venturi section increases after the passage of the venturi section. The flow rate increases due to the expansion effect. That is, the fastest part of the pressurized air is generated in the air flow path after passing through the venturi part (the range in which the flow path area is most restricted).
On the other hand, in the region where the channel area on the downstream side of the venturi increases, the pressure rapidly decreases due to the negative pressure associated with the diameter expansion of the channel. Thereby, the suction capability of the liquid fuel by the pores is enhanced.

The liquid fuel sucked out from the pores is continuously divided at a high speed by pressurized air having a flow rate faster than that of the pressurized air passing through the venturi section. That is, the shearing ability of liquid fuel by pressurized air is enhanced. In this way, the liquid fuel sucked out from the pores mixes with the pressurized air while being very finely divided by the pressurized air at a high flow rate. As a result, the mixing property of pressurized air and liquid fuel is promoted.
Then, since the liquid fuel mixed with the pressurized air is injected through the second injection hole, the spray particle size can be atomized from the initial injection of the second injector.

Thus, the air blast injector according to claim 1 is:
O The atomization particle size is atomized from the initial injection of the second injector using the Venturi effect,
-Increase the shearing ability of pressurized air to shear liquid fuel sucked out from the pores to promote the mixing of pressurized air and liquid fuel,
○ The suction speed of the liquid fuel in the center hole can be increased by increasing the suction capacity of the pores.

[Means of claim 2]
The venturi forming part of the second aspect forms a venturi part between the second needle body and the second needle by bulging radially inward on the inner peripheral surface of the second nozzle body.
Thereby, the effect of the said Claim 1 can be obtained by providing the fuel outlet of a pore in the side surface of a 2nd needle.

[Means of claim 3]
The fuel outlet of the pore of claim 3 is provided between the end position on the second injection hole side in the venturi section and a position 5 mm away from the end position toward the second injection hole.
By providing in this way, the effect of Claim 1 can be obtained.

[Means of claim 4]
The air blast injector according to claim 4 comprises:
The venturi forming portion bulges radially outward on the outer peripheral surface of the second needle, thereby forming a venturi portion with the second nozzle body.
Thereby, the effect of the said Claim 1 can be obtained by providing the fuel outlet of a pore directly under the venturi part in a venturi formation part.

[Means of claim 5]
The fuel outlet of the pore of claim 5 is provided in a flow velocity range in which the flow velocity of the pressurized air that has passed through the venturi portion exceeds Mach 1 due to the rubber nozzle effect.
By providing in this way, the effect of Claim 1 can be obtained.

It is principal part explanatory drawing in a 2nd injector (Example 1). It is explanatory drawing which shows the velocity distribution of the pressurized air in the vicinity of a venturi part, and the pressure distribution of pressurized air. It is sectional drawing of an air blast injector. It is a time chart which shows the example of a drive of a 1st injector and a 2nd injector. It is explanatory drawing which shows the flow of the fuel in a 1st injector. It is explanatory drawing which shows the flow of the pressurized air in a 2nd injector. It is principal part explanatory drawing in a 2nd injector (Example 2). It is principal part sectional drawing of an air blast injector (conventional example). It is principal part sectional drawing of an air blast injector (reference example).

A basic configuration of an air blast injector in the embodiment will be described with reference to the drawings.
The air blast injector includes a first injector 1 that injects pressurized liquid fuel, and a second injector 2 that injects pressurized air together with the liquid fuel injected from the first injector 1.

The first injector 1 has a first nozzle body 4 having a first injection hole 3 for injecting liquid fuel pressurized and supplied from the outside to the inside, and is accommodated in the first nozzle body 4 so as to be accommodated in the first injection hole 3. The first needle 5 that opens and closes the first needle 5 includes a first electromagnetic drive unit 6 that drives the first needle 5 (an example of an actuator that drives the first injector 1).
The 2nd injector 2 has the 2nd injection hole 7 which injects the liquid fuel injected from the 1st injector 1 with the air pressurized and supplied from the outside. The second injector 2 includes a second needle 9 that opens and closes the second injection hole 7 and a second nozzle body 8 that accommodates the second needle 9, and drives the second needle 9. A second electromagnetic drive unit 10 (an example of an actuator that drives the second injector 2) is provided.

And the 2nd injector 2 employ | adopts the following structures.
A center hole 11 extending from the upper part of the second needle 9 to the lower side is provided inside the second needle 9.
Between the second needle 9 and the second nozzle body 8, an air flow path 12 through which pressurized air flows toward the second injection hole 7 when the second injection hole 7 is opened is defined.

In the middle of the passage of the air flow path 12, a venturi forming section 14 is provided that forms a venturi section 13 that throttles the pressurized air that flows toward the second injection hole 7 when the second injection hole 7 is opened.
The second needle 9 is provided with a pore 15 for sucking the liquid fuel in the center hole 11 into the pressurized air that has passed through the venturi portion 13.

The fuel outlet of the pore 15 is opened downstream of the air flow from the venturi portion 13 (the range in which the flow path area is most narrowed).
An example of a preferred embodiment of the fuel outlet of the pore 15 will be described.
The fuel outlet of the pore 15 opens at a position where it passes through the venturi portion 13 and then comes into contact with the pressurized air (see arrow α in FIG. 1) that flows while keeping straight travel along the gap of the venturi portion 13. And
(I) When the venturi forming portion 14 is provided on the inner peripheral surface of the second nozzle body 8 (see FIG. 1), the same diameter as that between the venturi portion 13 and the second injection hole 7 and the venturi portion 13 The fuel outlet of the pore 15 is provided on the side surface of the second needle 9 having a size,
(Ii) When the venturi forming portion 14 is provided on the outer peripheral surface of the second needle 9 (see FIG. 7), the fuel outlet of the pore 15 is provided immediately below the venturi portion 13 in the venturi forming portion 14.

  Hereinafter, a specific example (example) to which the present invention is applied will be described with reference to the drawings. The embodiment discloses a specific example, and it goes without saying that the present invention is not limited to the embodiment. In the following embodiments, the same reference numerals as those in the above-mentioned [Mode for Carrying Out the Invention] denote the same functional objects.

[Example 1]
The air blast injector is mounted on a direct injection engine. For example, fuel such as gasoline is directly injected into a cylinder (combustion chamber) of the engine and is mounted on each cylinder.
The air blast injector includes a first injector 1 that injects liquid fuel, and a second injector 2 that injects pressurized air together with the liquid fuel injected from the first injector 1.

(Description of the first injector 1)
In the first injector 1 of the first embodiment, the fuel pressurized by the fuel pump is supplied to the inside through a fuel inlet 21 provided at the upper end of the first injector 1 through a fuel supply pipe.
The fuel pump is disposed in the middle of a fuel supply pipe that guides fuel from the fuel tank to the first injector 1. The fuel pump sucks the fuel in the fuel tank and pressurizes the fuel to a predetermined pressure, toward the first injector 1. It is to be pumped. The fuel pump also includes a pressure regulator (such as a pressure regulator) that regulates the pressure of the fuel discharged toward the first injector 1 to a predetermined target pressure (for example, 550 kPa).

The first injector 1 has a substantially cylindrical shape, receives fuel from the upper end, and injects fuel from the lower end via an internal fuel passage.
The first injector 1 includes a first injection nozzle 22 that performs fuel injection and stop, a first spring 23 that applies a valve closing force (force to stop fuel injection) to the first injection nozzle 22, and the first spring. A first electromagnetic drive unit 6 for applying a valve opening force (a force for executing fuel injection) against the valve closing force 23, and a first lower body that has a substantially cylindrical shape and is inserted and fixed to the upper portion of the second injector 2. 24. The first upper body 25 has a substantially cylindrical shape and is coaxially disposed on the upper portion of the first lower body 24, and flows into the inside from a fuel inlet 21 provided at the upper end of the first upper body 25. The fuel thus supplied is supplied toward the lower end of the first injection nozzle 22 through the first lower body 24.

The first injection nozzle 22 is fixed to the lower part of the first lower body 24 and is inserted and arranged in the second injector 2. The first injection nozzle 22 is accommodated in the first nozzle body 4 and is vertically moved. And a first needle 5 that is slidably supported.
A first nozzle hole 26 is formed in the axial center of the first nozzle body 4 to guide fuel from above to below, and at the center of the valve seat provided at the lower end of the first nozzle hole 26, A first injection hole 3 for injecting fuel from the tip of the first nozzle body 4 toward the inside of the second injector 2 is formed.

The first nozzle hole 26 forms a fuel passage between the first needle 5 and guides the fuel supplied from above to the valve seat side.
The first injection hole 3 is one through-hole penetrating in the vertical direction at the axial center of the lower end of the first nozzle body 4, the inlet is open on the upper surface of the valve seat, and the outlet is the tip of the first nozzle body 4. Open to the outer surface of the part.

The first needle 5 has a shaft shape extending in the vertical direction, and is supported at the center of the first nozzle hole 26 so as to be slidable in the vertical direction.
Specifically, the upper end of the first needle 5 is coupled to the center of a first movable core 27 (an armature in the first electromagnetic drive unit 6) that is slidably supported by the inner peripheral surface of the first lower body 24 in the vertical direction. As a result, the upper end of the first needle 5 is supported inside the first lower body 24 so as to be movable in the vertical direction. The first movable core 27 is formed with a fuel passage 27 a that communicates in the vertical direction, and is provided so as to guide the fuel on the upper side of the first movable core 27 to the lower side of the first movable core 27. Yes.

  On the other hand, a first large-diameter sliding portion 28 bulging outward in the radial direction is formed below the first needle 5, and the first large-diameter sliding portion 28 is formed in the first nozzle hole 26. It is slidably supported by the peripheral surface. The first large-diameter sliding portion 28 is provided with a communicating portion (chamfered portion, groove portion) 28a that communicates in the vertical direction. It is provided so as to lead to the lower side of the large-diameter sliding portion 28.

The lower end of the first needle 5 is provided with a seat portion that can be seated on a valve seat provided at the lower end of the first nozzle hole 26. When the seat portion is seated on the valve seat, the communication between the first nozzle hole 26 and the first injection hole 3 is blocked, and when the seat portion is separated from the valve seat, the first nozzle hole 26 and the first nozzle hole 26 are separated from each other. The fuel is injected from the first injection hole 3 in communication with the injection hole 3.
Here, a contact portion (seat portion) between the valve seat and the seat portion is provided with a line seal portion (oil-tight function portion) for stopping injection when the seat portion is seated on the valve seat. .
Note that the shape of the seat portion is not limited to a substantially conical shape, and may be any shape as long as the shape can be line-sealed, such as a substantially truncated cone shape or a substantially hemispherical shape. Further, the sealing method of the valve seat and the seat portion is not limited to the line seal, but may be a seal by contact with a conical surface.

  The first spring 23 presses the first needle 5 downward and generates a force (valve closing force) for seating the seat portion on the valve seat. In the first embodiment, a compression coil spring is used. Specifically, the first spring 23 is assembled in a compressed state between the first movable core 27 and the cylindrical first spring stopper 29. Here, the first spring stopper 29 is fixed to the inner peripheral surface of a first magnetic attracting cylinder 34 (described later) fixed to the inner peripheral surface of the first upper body 25 by press-fitting or screwing.

  The first electromagnetic drive unit 6 drives the first needle 5 upward (in the valve opening direction) by a magnetic force. The first coil 31 wound in a cylindrical shape that generates a magnetic force when energized, the first coil. The first movable core 27 is provided on the inner periphery of the first movable core 27 and is slidably supported in the vertical direction. The first stator forms a magnetic path for magnetically attracting the first movable core 27 upward.

The first stator has a first nonmagnetic cylinder 32 disposed between the first lower body 24 and the first upper body 25, and a diameter of the first movable core 27 at the lower portion of the first nonmagnetic cylinder 32. A first magnetic transfer cylinder 33 for transferring the direction of magnetism, a first magnetic attraction cylinder 34 for magnetically attracting the first movable core 27 upward, and a first yoke 35 covering the periphery of the first coil 31.
Of the members constituting the first stator, all the members other than the first nonmagnetic cylinder 32 (the first magnetic delivery cylinder 33, the first magnetic attraction cylinder 34, and the first yoke 35) are all magnetic metal. (For example, iron).
Here, the first stator uses a part of the first lower body 24 and the first upper body 25, and the upper portion of the first lower body 24 is used as the first magnetic delivery tube 33, and the first upper body is used. 25 is used as a member for magnetically coupling the first magnetic suction cylinder 34 and the first yoke 35.

The first non-magnetic cylinder 32 is a cylinder having the same diameter as the first upper body 25, and the first magnetic attraction cylinder 34 and the first magnetic delivery cylinder 33 (a part of the first lower body 24) are the first movable. This is to prevent direct magnetic coupling (magnetic path formation) without going through the core 27.
The first magnetic attraction cylinder 34 has a cylindrical shape coupled to the inner peripheral surface of the first upper body 25, and a main gap (magnetic) is formed between the lower surface of the first magnetic attraction cylinder 34 and the upper surface of the first movable core 27. (Suction gap). That is, when the first coil 31 is energized, the first magnetic attraction cylinder 34 magnetically attracts the first movable core 27.

  The first yoke 35 is a member that covers the outer periphery of the first coil 31 and forms a magnetic path around the first coil 31. When the first coil 31 is energized, the first yoke 35 → the first upper. Body 25 and first magnetic attraction cylinder 34 → first movable core 27 → first magnetic delivery cylinder 33 (a part of the first lower body 24) → magnetic path returning to the first yoke 35 (the direction of flow of magnetic flux is opposite) May be formed).

  The first yoke 35 is molded with an insulating first resin member 36, and a first connector 37 for external connection is provided on a part of the first resin member 36 that molds the first yoke 35. Yes. The first connector 37 is a connection means for making an electrical connection via a connection line with an ECU (engine control unit: not shown) that controls the operation of the first injector 1. Terminals 37a connected to both ends of the first coil 31 are molded.

(Description of the second injector 2)
In the second injector 2 of the first embodiment, the air pressurized by the air pump is supplied to the inside from the upper side surface of the second injector 2 through the compressed air supply pipe.
The air pump sucks air in the atmosphere, pressurizes it to a predetermined pressure, and pumps it toward the second injector 2. The air pump adjusts the pressure of the air discharged toward the second injector 2 to a predetermined target pressure (pressure lower than the fuel pressure supplied from the fuel pump to the first injector 1; for example, 300 kPa). A pressure regulator (pressure regulator, etc.) is provided.

  The second injector 2 has a substantially cylindrical shape arranged coaxially with the first injector 1 on the lower side of the first injector 1 and receives injected fuel from the first injector 1 arranged on the upper side. Pressurized air is supplied from the air pump. The second injector 2 includes pressurized air and liquid fuel supplied to the upper portion of the second injector 2 (hereinafter, pressurized air supplied to the second injector 2 and liquid injected from the first injector 1. The fuel is combined with the fuel and described as an air-mixed fuel) through the internal passage to the lower end and injected from the lower end.

  The second injector 2 includes a second injection nozzle 38 that executes injection and stop of air-mixed fuel, a second spring 39 that applies a valve closing force (force to stop fuel injection) to the second injection nozzle 38, 2nd electromagnetic drive part 10 which gives valve opening force (force which performs fuel injection) against the valve closing force of 2 springs 39, the 2nd which is inserted in a cylinder head etc. of an engine in the shape of a cylinder, etc. The lower body 40 is provided with a second upper body 41 that has a substantially cylindrical shape and is coaxially disposed on the upper portion of the second lower body 40.

The second upper body 41 has a substantially cylindrical shape as described above, and the lower portion of the first injector 1 is inserted and disposed on the upper portion thereof. As an example of fixing the first injector 1 to the second upper body 41, in this embodiment, a flange portion 24a is provided on the outer periphery of the first lower body 24, the upper surface of the second upper body 41, and the upper surface of the second upper body 41. The first injector 1 is fixed to the second upper body 41 by sandwiching the flange portion 24 a between the mounting plate 42 and the mounting plate 42. Note that the fixing means of the first injector 1 can be changed as appropriate.
In addition, an air introduction passage 43 that guides air pressurized by an air pump to the inside is formed on the side surface of the second upper body 41. The pressurized air supplied to the inside of the second upper body 41 is supplied and supplied to the second injection nozzle 38.

The second injection nozzle 38 is fastened and fixed to the lower portion of the second lower body 40 using a retaining nut 44, and is housed in the second nozzle body 8 so as to be slidable in the vertical direction. The second needle 9 is supported by the second needle 9.
The second nozzle body 8 is inserted and arranged so that the tip portion is exposed in the cylinder, and a cylindrical second nozzle hole 45 penetrating from the upper side to the lower side is formed at the axial center thereof. ing.
The second injector 2 includes a second injection hole 7 at the lower end of the second nozzle body 8 for supplying air-mixed fuel into the cylinder. The second injection hole 7 is formed between the second needle 9 and the lower end of the second nozzle hole 45 (opening hole having a tapered shape whose diameter is expanded downward and communicating with the outside). The second needle 9 is opened and closed.

The second nozzle hole 45 forms a cylindrical air passage 12 that communicates with the second needle 9 in the up-down direction. The second nozzle hole 45 receives the pressurized air and liquid fuel supplied to the air passage 12 in the first direction. 2 It leads to the injection hole 7.
The second needle 9 has a shaft shape extending in the vertical direction, and is supported at the center of the second nozzle hole 45 so as to be slidable in the vertical direction.

  Specifically, the upper end of the second needle 9 is at the center of the second movable core 46 (the armature in the second electromagnetic drive unit 10) supported by the inner peripheral surface of the second upper body 41 so as to be slidable in the vertical direction. As a result, the upper end of the second needle 9 is supported so as to be movable in the vertical direction inside the second upper body 41. The second movable core 46 is not formed with a passage for communicating in the vertical direction, and the liquid fuel adhering to the outer periphery of the second needle 9 due to some factor is present on the outer peripheral surface of the second movable core 46. By being transmitted downward through the sliding clearance, it is guided to the lower air flow path 12.

On the other hand, the second large-diameter sliding portion 47 for slidably supporting the lower side of the second needle 9 is formed on the inner peripheral surface of the second nozzle body 8. This is because the first embodiment employs a structure in which a later-described venturi forming portion 14 is formed on the inner peripheral surface of the second nozzle body 8.
Specifically, the second large-diameter sliding portion 47 according to the first embodiment bulges inward in the radial direction at an intermediate portion in the vertical direction of the second nozzle hole 45 in the second nozzle body 8. The inner peripheral surface of the large-diameter sliding portion 47 supports the outer peripheral surface of the second needle 9 so as to be slidable. The second large-diameter sliding portion 47 is provided with a communicating portion (groove portion or the like) 47a that communicates in the vertical direction, and the pressurized air supplied to the upper side of the second large-diameter sliding portion 47 is lowered. It is provided to guide to the side.

Inside the second needle 9, the inside of the needle includes a center hole 11 that guides the fuel injected by the first injector 1 and the pressurized air supplied from the air introduction passage 43 to the inside of the second upper body 41 downward. A passage is provided.
The upper end of the center hole 11 opens on the same axis as the first injection hole 3 of the first injector 1, and the liquid fuel injected by the first injector 1 and pressurized air supplied from outside are supplied to the center hole 11. It functions as an introduction port leading to the inside of the.

Here, as a means for supplying fuel from the first injection hole 3 to the inside of the center hole 11, all liquid fuel injected from the first injection hole 3 is positively supplied to the first injector 1 of this embodiment. A fuel nozzle 48 for supplying to the center hole 11 is provided. The fuel nozzle 48 is a hollow thin pipe that extends from the first injection hole 3 to the inside of the center hole 11, and the lower end of the fuel nozzle 48 extends to the inside of the center hole 11.
The liquid fuel injected from the first injector 1 is supplied to the center hole 11 through the fuel nozzle 48, and the pressurized air supplied from the air introduction passage 43 to the inside of the second upper body 41 is the fuel nozzle. It is supplied to the center hole 11 through an annular passage formed between the outer wall of 48 and the inner wall of the center hole 11.

  The fuel nozzle 48 is integrally provided with a cap-shaped cap portion that is attached to the lower end of the first nozzle body 4. The fuel nozzle 48 extends downward at the center of the cap portion. Yes. Then, the cap portion is fitted to the lower end of the first nozzle body 4 and fixed to the first nozzle body 4 by a fixing technique such as welding, so that the fuel nozzle 48 communicates with the first injection hole 3 in the first state. It is attached to the injector 1.

In this way, by fixing the cap portion to the end portion of the first nozzle body 4, the periphery of the first injection hole 3 is sealed between the cap portion and the first nozzle body 4 over the entire circumference. As a result, it is possible to avoid a problem that the fuel injected from the first injector 1 leaks from a location different from the tip of the fuel nozzle 48 (the end inserted into the center hole 11).
In this embodiment, an example in which a substantially cup-shaped cap portion is used as a means for attaching the fuel nozzle 48 to the first nozzle body 4 is shown. However, the fuel is applied to the first nozzle body 4 by using another shape fixing means. The nozzle 48 may be fixed.

Here, the passage area inside the fuel nozzle 48 is provided larger than the passage area of the first injection hole 3. Thereby, the malfunction which the fuel nozzle 48 influences the fuel injected from the 1st injector 1 can be avoided.
The amount of overlap between the center hole 11 and the fuel nozzle 48 in the axial direction ensures that the fuel injected from the first injector 1 does not spill outside from the upper end opening of the center hole 11. However, since the passage resistance of the pressurized air passing through the annular passage is increased by setting the overlap amount to be long, the overlap amount in the axial direction of the center hole 11 and the fuel nozzle 48 is longer than necessary. It is set not to do so.

  By using this fuel nozzle 48, all the liquid fuel injected from the first injector 1 can be stably guided to the second injection hole 7 through the center hole 11 and injected from the first injector 1. The time and amount until all the fuel is guided to the second injection hole 7 is stabilized. As a result, it is possible to inject fuel with high accuracy while the second injection hole 7 is being opened, and it is possible to improve fuel injection accuracy.

In the second injector 2 shown in this embodiment, as a means for guiding the pressurized air supplied into the second upper body 41 to the air flow path 12, it is not necessary to provide the upper and lower through holes in the second movable core 46. The center hole 11 inside the second movable core 46 is used.
Specifically, the second needle 9 has a lateral hole that communicates with the air passage 12 (the outer space of the second needle 9) below the second movable core 46 and in the middle of the passage in the vertical direction in the center hole 11. 49 is provided. The lateral hole 49 is an air branch hole that divides the pressurized air supplied into the center hole 11 and supplies it to the air flow path 12, and the pressurized air passes through the center hole 11 and the lateral hole 49. 12 is filled and supplied.

In addition, the inner diameter dimension of the horizontal hole 49 is set large so that the amount of pressurized air flowing through the air flow path 12 is not restricted by the horizontal hole 49.
Further, the internal volume of the center hole 11 below the horizontal hole 49 is set larger than the fuel injection amount (maximum injection amount) at one time, and the liquid fuel injected from the first injector 1 is allowed to flow below the horizontal hole 49. It is provided so that it can be stored in the center hole 11 on the side.
Thereby, even at the time of the maximum injection, there is no problem that the liquid fuel overflows from the side hole 49 to the air flow path 12, and the liquid fuel overflowing from the air flow path 12 is gathered together at the initial stage of the injection to the second injection hole. There is no problem injecting from 7 to the outside.

A valve umbrella 51 that opens and closes the second injection hole 7 is provided at the lower end of the second needle 9. The outer diameter dimension of the valve umbrella 51 is larger than the outer diameter dimension of the second injection hole 7, and when the valve umbrella 51 is seated on the opening edge of the second injection hole 7, the air flow path 12. Is disconnected from the outside (inside the cylinder), and the valve head 51 is separated from the opening edge of the second injection hole 7, whereby the air flow path 12 and the outside communicate with each other, and the air is discharged from the second injection hole 7. The mixed fuel is injected into the cylinder.
Here, at the opening edge of the second injection hole 7 in contact with the valve umbrella 51, a line seal portion (oil-tight function) for stopping injection when the valve umbrella 51 is seated on the opening edge of the second injection hole 7. Part). In addition, the form of the 2nd injection hole 7 and the form of the valve body (valve part which opens and closes the 2nd injection hole 7) in the 2nd needle 9 are not limited to what is shown in this Example, It changes suitably. It is possible.

  The second spring 39 generates a force (valve closing force) that pushes the second needle 9 upward and seats the valve umbrella 51 on the opening edge of the second injection hole 7. In the first embodiment, the second spring 39 is compressed. A coil spring is used. Specifically, the second spring 39 is assembled in a compressed state between the second spring stopper 52 attached to the outer peripheral surface of the second needle 9 and the upper end surface of the second nozzle body 8. is there. The second spring stopper 52 is supported by a clip ring (E ring, C ring, etc.) 52 a attached to the outer peripheral surface of the second needle 9.

  The second electromagnetic drive unit 10 drives the second needle 9 downward (in the valve opening direction) by a magnetic force, and a second coil 53 wound in a cylindrical shape that generates a magnetic force when energized, the second coil. The second movable core 46 is disposed on the inner periphery of the second movable core 46 and is slidably supported in the vertical direction. The second movable core 46 includes a second stator that forms a magnetic path for magnetically attracting the second movable core 46 downward.

The second stator has a second non-magnetic cylinder 54 disposed between the second lower body 40 and the second upper body 41, and a diameter of the second movable core 46 and the upper diameter of the second non-magnetic cylinder 54. A second magnetic transfer cylinder 55 that transfers the direction of magnetism, a second magnetic attraction portion 56 that magnetically attracts the second movable core 46 downward, and a second yoke 57 that covers the periphery of the second coil 53.
Of the members constituting the second stator, all members other than the second non-magnetic cylinder 54 (second magnetic delivery cylinder 55, second magnetic attraction portion 56, second yoke 57) are all magnetic metal. (For example, iron).
Here, the second stator uses a part of the second lower body 40 and the second upper body 41, and the upper part of the second lower body 40 is used as the second magnetic attraction portion 56, and the second upper body is used. The lower part of 41 is used as the second magnetic delivery cylinder 55.

The second nonmagnetic cylinder 54 is a cylinder having the same diameter as the lower part of the second upper body 41, and includes a second magnetic attraction portion 56 (a part of the second lower body 40) and a second magnetic delivery cylinder 55 (second upper body). This is to prevent a part of the body 41 from being directly magnetically coupled (magnetic path formation) without the second movable core 46 being interposed.
The second magnetic attraction unit 56 is a member that is disposed opposite to the lower surface of the second movable core 46 and forms a main gap (magnetic attraction gap) between the lower surface of the second movable core 46. That is, when the second coil 53 is energized, the second magnetic attraction unit 56 magnetically attracts the second movable core 46.

  The second yoke 57 is a member that covers the outer periphery of the second coil 53 and forms a magnetic path around the second coil 53. When the second coil 53 is energized, the second yoke 57 → second magnetic field. Attraction section 56 (part of second lower body 40) → second movable core 46 → second magnetic delivery cylinder 55 (part of second upper body 41) → magnetic path returning to second yoke 57 again (flow direction of magnetic flux) May be reversed).

  The second yoke 57 is molded by an insulating second resin member 58, and a second connector 59 for external connection is provided on a part of the second resin member 58 that molds the second yoke 57. Yes. The second connector 59 is a connection means for making an electrical connection with the ECU for controlling the operation of the second injector 2 through a connection line, and terminals connected to both ends of the second coil 53 inside thereof. 59a is molded.

The ECU includes a CPU for performing control processing and arithmetic processing, a storage device for storing various programs and data (memory such as ROM, RAM, SRAM or EEPROM), an input circuit, an output circuit, a power supply circuit, and the like. A microcomputer having a structure and an injector driving circuit for performing energization control of the first coil 31 and the second coil 53 in accordance with an instruction of the microcomputer.
The microcomputer controls energization of the first and second coils 31 and 53 in accordance with signals of sensors read by the ECU (engine parameters: signals corresponding to the operating state of the occupant, the operating state of the engine, etc.). An injector control program is installed.

The injector control program calculates the injection mode, injection timing, and fuel injection amount according to the driving state from the driving state of the vehicle read into the ECU, and calculates the calculated injection mode, injection timing, and fuel injection. The energization control of the first and second coils 31 and 53 is performed so that the amount can be obtained.
Specifically, the injector control program controls the energization period of the first coil 31 so that the calculated injection amount is obtained, and the second coil 53 is controlled so that fuel injection is performed at the calculated injection timing. Control the energization start time. That is, in the second injector 2, the energization control of the first and second injectors 1 and 2 is performed so that the pressurized air is injected together with the liquid fuel injected from the first injector 1.

For example, as shown in FIG. 4, first, a drive signal for the first injector 1 is output to the first coil 31 to supply fuel from the first injector 1 into the second injector 2, and then the second A drive signal for the second injector 2 is output to the coil 53 to inject the air-mixed fuel from the second injector 2 into the cylinder.
4 is merely an example, and unlike FIG. 4, there may be an overlap period in which the first injector 1 and the second injector 2 are driven simultaneously, or the first injector 1 and the first injector 1 The two injectors 2 may be driven simultaneously.

(Background of Example 1)
In the conventional air blast injector shown in FIG. 8, the liquid fuel injected and supplied from the first injector 1 to the center hole 11 passes through the thick hole J1 from the lower end of the center hole 11 and accumulates at the lower end of the air flow path 12. And if the 2nd injection hole 7 opens, the liquid fuel collected at the lower end of the air flow path 12 will be pushed out and injected by pressurized air.
As a result, at the initial opening of the second injection hole 7 (initial injection), the liquid fuel collected at the lower end of the air flow path 12 is pushed out from the second injection hole 7 in a collective state, and the injection is performed. The initial spray particle size becomes large.

  As a means for avoiding this problem, as shown in the reference example of FIG. 9, a venturi portion 13 that restricts the flow area of the pressurized air is provided in the middle of the passage of the air flow passage 12, and the venturi portion extends from the lower end of the center hole 11. It is conceivable that the atomized particle diameter is atomized from the initial stage of injection by providing the pore 15 leading to 13 and sucking fuel from the pore 15 into the pressurized air passing through the venturi section 13.

However, when analyzing the flow state of the pressurized air passing through the venturi section 13,
(I) As shown by the arrow α in FIG. 1, the pressurized air that has passed through the venturi portion 13 flows while maintaining straightness along the gap of the venturi portion 13,
(Ii) As shown in FIG. 2A, the passing speed of the pressurized air after passing through the venturi section 13 is faster than the passing speed of the pressurized air passing through the venturi section 13. I found.
Specifically, after passing through the venturi section 13, the flow velocity of the pressurized air in the venturi section 13 is higher than that in the venturi section 13 in a wide range where the straight flow is maintained along the gap of the venturi section 13.
In particular, it has been found by speed analysis that the passing speed of the pressurized air immediately after passing through the venturi section 13 exceeds Mach 1 (sound speed) due to the Rubbers nozzle effect.
In addition, the number with the code | symbol S attached | subjected to the arrow in Fig.2 (a) shows that speed is so quick that the number attached | subjected to the code | symbol S is large.

On the other hand, when analyzing the pressure state of the pressurized air around the venturi portion 13,
(Iii) As shown in FIG. 2 (b), the pressure in the air flow path 12 on the downstream side (lower side) of the venturi section 13 is lower than the pressure in the venturi section 13.
In addition, the number with the code | symbol P which shows the inside of a broken-line boundary in FIG.2 (b) shows that a pressure is so high that the number attached | subjected to the code | symbol P is large.

(Characteristic technology of Example 1)
Therefore, in view of the above analysis results, the air blast injector of this Example 1 is
(I) The basic configuration is to achieve atomization at the initial stage of injection of the second injector 2 using the Venturi effect,
(Ii) The liquid fuel is sucked out from the pores 15 by the pressurized air having a flow velocity faster than that of the venturi section 13, and the shearing ability of the pressurized air to shear the liquid fuel sucked out from the pores 15 is increased.
(Iii) Further, the liquid fuel is sucked out from the pores 15 in a lower pressure range than the venturi portion 13 so as to enhance the sucking ability of the pores 15 to suck out the liquid fuel accumulated in the center hole 11.

Specifically, the air blast injector according to the first embodiment employs the following configuration in order to achieve the above.
(A) A center hole 11 through which the fuel injected from the first injector 1 is supplied is provided inside the second needle 9.
(B) Between the 2nd needle 9 and the 2nd nozzle body 8, the air flow path 12 into which pressurized air flows toward the 2nd injection hole 7 at the time of valve opening of the 2nd injection hole 7 is divided. .
(C) A venturi forming portion 14 for forming a venturi portion 13 for restricting pressurized air is provided in the middle of the passage of the air flow path 12.
(D) The second needle 9 is provided with pores 15 for sucking the liquid fuel supplied into the center hole 11 into the pressurized air that has passed through the venturi portion 13.
(E) The fuel outlet of the pore 15 opens on the downstream side of the air flow with respect to the venturi portion 13 (the range in which the flow path area is most restricted). Specifically, the fuel outlet of the pore 15 is provided at a position where the fuel outlet is in contact with the pressurized air that flows while maintaining straight advanceability along the gap of the venturi portion 13 after passing through the venturi portion 13.

The above configuration will be specifically described with reference to FIG.
The pores 15 are a plurality of inner and outer communication holes that are provided radially from the lower end of the center hole 11 toward the radially outer side, and are provided as inclined holes that are inclined downward from the center side toward the outer side. Further, the inner diameter dimension of the pore 15 is set to a diameter dimension that suppresses the liquid fuel accumulated in the center hole 11 from leaking to the outer peripheral portion of the second needle 9 due to gravity.

Further, the lowermost end portion of the center hole 11 is provided so as to communicate with the pore 15. That is, a conical bottom end formed when the center hole 11 is drilled from the upper end of the second needle 9 with a drill is provided in communication with the pore 15.
In this way, by communicating the lowermost end portion of the center hole 11 with the pore 15, the liquid fuel at the lowermost end portion of the center hole 11 is sucked out through the pore 15 when the second injector 2 is operated. Thus, it is possible to avoid the problem that the liquid fuel is stored in the center hole 11 after the injection of the second injection hole 7.

The venturi forming portion 14 of the first embodiment bulges radially inward on the inner peripheral surface of the second nozzle body 8 at a position below the second large-diameter sliding portion 47, so that the outer peripheral surface of the second needle 9 A venturi portion 13 that functions as a flow path restriction for the air flow path 12 is formed between the two. The upper side of the venturi forming portion 14 is provided on a tapered surface that gradually squeezes pressurized air from above toward the maximum throttle portion of the venturi portion 13. Further, the lower side of the venturi forming portion 14 is provided on a tapered surface that gradually expands the pressurized air squeezed by the maximum throttle portion of the venturi portion 13.
The clearance distance between the venturi portion 13 (the clearance amount between the second needle 9 and the venturi forming portion 14) and the axial distance of the venturi portion 13 (the vertical length within the range forming the minimum throttle portion) are determined by the venturi portion 13. The flow rate of the pressurized air passing therethrough is set to be the fastest (Mach 1 or a speed close to Mach 1).

On the other hand, the outer peripheral surface of the second needle 9 facing the venturi forming portion 14 is a cylindrical surface that is linear in the axial direction at least in the range from the upper portion of the venturi portion 13 to the lower portion of the venturi portion 13 (the outer peripheral surface is straight in the axial direction). Is provided on a cylindrical surface).
Specifically, as for the outer peripheral surface of the second needle 9 in the first embodiment, the upper side of the valve head 51 is all provided on a cylindrical surface that is linear in the axial direction.

With the above configuration, as indicated by an arrow α in FIG. 1, the pressurized air that has passed through the venturi portion 13 flows while maintaining straightness so as to follow the gap between the venturi portions 13. That is, the pressurized air that has passed through the venturi portion 13 flows along the outer peripheral surface of the second needle 9. Therefore, a fuel outlet (outer radial outlet) of the pore 15 is provided on the side surface of the second needle 9 between the venturi portion 13 and the second injection hole 7.
By providing in this way, after passing through the venturi part 13, the position where it comes into contact with the pressurized air (pressurized air whose flow velocity is higher than that of the venturi part 13) that flows straightly along the gap of the venturi part 13. A fuel outlet for the pores 15 can be provided.
A preferable exit position of the pore 15 will be described later.

Next, the operation of the air blast injector employing the above configuration will be described.
The ECU operates the first injector 1 when fuel injection is performed in the cylinder of the engine.
The operation of the first injector 1 will be described with reference to FIG. When energization of the first coil 31 is started by the ECU, the first movable core 27 is magnetically attracted upward by the magnetic force. Then, when the magnetic attractive force that drives the first movable core 27 upward overcomes the valve closing direction load applied to the first needle 5, the first movable core 27 moves upward and is coupled to the first movable core 27. The first needle 5 is starting to lift up. When the first needle 5 is separated from the valve seat, the pressurized fuel supplied to the first nozzle hole 26 of the first nozzle body 4 is injected from the first injection hole 3.
The fuel injected from the first injection hole 3 passes through the fuel nozzle 48 and is supplied to the inside of the center hole 11 of the second injector 2. That is, the fuel injected from the first injector 1 is injected only into the center hole 11 of the second injector 2 by the fuel nozzle 48.

  When energization of the first coil 31 is stopped by the ECU, the magnetic force that magnetically attracted the first movable core 27 upward is lost. Then, the first movable core 27 and the first needle 5 start to descend by the urging force of the first spring 23. When the first needle 5 is lowered and seated on the valve seat, the communication between the first nozzle hole 26 and the first injection hole 3 is cut off, the fuel injection from the first injection hole 3 is stopped, and the center hole 11 is stopped. The fuel supply (fuel injection) to the inside of is stopped.

The ECU operates the second injector 2 in addition to the first injector 1 when performing fuel injection into the cylinder of the engine.
The operation of the second injector 2 will be described with reference to FIG. When energization of the second coil 53 is started by the ECU, the second movable core 46 is magnetically attracted downward by the magnetic force. When the magnetic attractive force that drives the second movable core 46 downward overcomes the valve closing direction load applied to the second needle 9, the second movable core 46 moves downward and is coupled to the second movable core 46. The second needle 9 is started to descend. And if the valve head 51 provided in the lower end of the 2nd needle 9 leaves | separates from the opening edge of the 2nd injection hole 7, the lower end of the air flow path 12 and the inside of a cylinder of an engine will communicate, and the inside of the 2nd injector 2 The liquid fuel stored in the center hole 11 is injected into the cylinder of the engine through the second injection hole 7 together with the pressurized air filled in the engine.

This state (injection of the liquid fuel stored in the center hole 11) will be described with reference to FIG.
When the second injection hole 7 is opened, the pressurized air filled in the air flow path 12 flows into the cylinder through the second injection hole 7. For this reason, a flow of pressurized air from the upper side of the venturi portion 13 toward the lower second injection hole 7 is generated in the air flow path 12, and the pressurized air is throttled by the venturi portion 13.
The flow rate of the pressurized air passing through the venturi section 13 increases due to fluid compression by the venturi section 13, and the passing speed reaches Mach 1 (or a flow speed close to Mach 1).

The pressurized air that has reached Mach 1 (or a flow velocity close to Mach 1) during the passage of the venturi section 13 has a fluid expansion effect in a region where the flow area on the downstream side of the venturi section 13 increases after the passage of the venturi section 13. Increases the flow rate. That is, the fastest part of the pressurized air that passes through the venturi portion 13 is generated in the air flow path 12 after passing through the venturi portion 13.
On the other hand, in the region where the flow channel area on the downstream side of the venturi portion 13 increases, the pressure rapidly decreases due to the negative pressure accompanying the expansion of the flow channel.

Therefore, the fuel outlet of the pore 15 is provided at a position where it touches the pressurized air (arrow α in FIG. 1) that flows through the venturi portion 13 and flows straightly along the gap of the venturi portion 13. Yes.
The air flow path 12 at the portion where the fuel outlet of the pore 15 is provided has a pressure lower than that of the venturi portion 13, and the liquid fuel suction capability by the pore 15 is enhanced.

Further, the liquid fuel sucked out from the pores 15 is continuously divided at a high speed by pressurized air having a flow velocity faster than that of the pressurized air passing through the venturi section 13. That is, the shearing ability of liquid fuel by pressurized air is enhanced.
Then, the liquid fuel sucked out from the pores 15 is mixed with the pressurized air while being very finely divided, thereby promoting the mixing of the pressurized air and the liquid fuel, and passing through the second injection hole 7 to the cylinder. Injected in.
Thus, since the liquid fuel sucked out from the fine holes 15 is injected from the second injection holes 7 in a state of being mixed with the pressurized air, it is possible to atomize the spray particle diameter from the initial injection of the second injector 2. it can.

  When the injection of the liquid fuel supplied to the second injector 2 is completed, the energization of the second coil 53 is stopped by the ECU. Then, the magnetic force that magnetically attracted the second movable core 46 downward is lost. As a result, the second movable core 46 and the second needle 9 start to rise due to the urging force of the second spring 39. When the second needle 9 is raised and the valve head 51 is seated on the opening edge of the second injection hole 7, the communication between the air flow path 12 and the cylinder of the engine is cut off, and the engine is connected to the engine from the second injection hole 7. The injection of the air mixed fuel into the cylinder is stopped.

(Effect of Example 1)
As described above, the second injector 2 in the air blast injector according to the first embodiment performs the injection while mixing the liquid fuel sucked out from the pores 15 with the pressurized air using the venturi effect. The sprayed particle diameter can be atomized from the initial stage of injection without injecting a liquid fuel. That is, the spray particle diameter can be atomized in the entire injection period from the initial injection of the second injector 2 to the end of the injection.
Further, since the shearing ability of the pressurized air to shear the liquid fuel sucked out from the pores 15 is enhanced, the mixing property between the pressurized air and the liquid fuel immediately before the injection can be promoted. As a result, the division of the fuel injected from the second injection hole 7 can be further promoted, and the atomization of the fuel spray in the cylinder can be improved.
Furthermore, since the suction ability of the liquid fuel sucked out by the pores 15 is enhanced, the liquid fuel in the center hole 11 can be sucked out in a short time. Further, it is possible to avoid the problem that the liquid fuel remains in the center hole 11.

(Feature Technology 2 of Example 1)
The pressurized air immediately after passing through the venturi section 13 has a flow velocity exceeding Mach 1 (sound speed) due to the rubber nozzle effect generated by the passage area of the air flow path 12 being expanded after passing through the venturi section 13.
Therefore, in the first embodiment, as shown in FIG. 1, the fuel outlet of the pore 15 is provided in a region where the flow rate of the pressurized air exceeds the Mach 1.

Thus, by providing the fuel outlet of the pore 15 in the region where the flow rate of the pressurized air exceeds Mach 1, the shearing ability of the pressurized air to shear the liquid fuel sucked out from the pore 15 is very high. Can be bigger.
As a result, the mixing property of pressurized air and liquid fuel can be promoted, and atomization of fuel spray can be improved.

(Feature Technology 3 of Example 1)
The range where the flow velocity exceeds Mach 1 cannot be specified without a special analysis device.
Therefore, in the case of an air blast injector used in a gasoline engine for a vehicle, a position between the lower end position (0 mm) of the venturi section 13 and a position 5 mm away from the lower end position {range where the flow velocity exceeds Mach 1: Within the range indicated by L1 in FIG. 2A, the fuel outlet of the pore 15 is provided.
Between the lower end position (0 mm) of the venturi portion 13 and 5 mm downward, the flow velocity is particularly high among the pressurized air that flows straight through the venturi portion 13 and passes along the gap of the venturi portion 13. Therefore, by providing the fuel outlet of the pore 15 in this range, the shearing ability of the pressurized air to shear the liquid fuel sucked out from the pore 15 is greatly increased. And mixing of liquid fuel can be promoted.

As a particularly preferred form, between a position 1 mm away from the lower end of the venturi 13 and a position 3 mm away from the lower end of the venturi 13 {within the range indicated by L2 in FIG. 2 (a)} It is desirable to provide a fuel outlet for the pores 15.
Between 1 mm downward from the lower end position of the venturi part 13 and 5 mm downward from the lower end position of the venturi part 13, after passing through the venturi part 13, the straight flow is maintained along the gap of the venturi part 13. Since it is the range where the flow velocity is the fastest among the pressurized air, by providing the fuel outlet of the pore 15 in this range, the shearing ability of the pressurized air to shear the liquid fuel sucked out from the pore 15 Can be maximized and the mixing of pressurized air and liquid fuel can be promoted.

[Example 2]
Embodiment 2 will be described with reference to FIG. In the following second embodiment, the same reference numerals as those in the first embodiment denote the same functional objects.
In the first embodiment, an example in which the venturi forming portion 14 is provided on the inner peripheral surface of the second nozzle body 8 has been described.
On the other hand, in the second embodiment, the venturi forming portion 14 is provided on the outer peripheral surface of the second needle 9.
Specifically, the venturi forming portion 14 of the second embodiment bulges radially outward on the outer peripheral surface of the second needle 9 at a position below the second large-diameter sliding portion 47, so that the second nozzle body 8 The venturi portion 13 is formed between the inner peripheral surface of the first and second inner surfaces.
In the second embodiment, the second large-diameter sliding portion 47 for slidably supporting the lower side of the second needle 9 as the venturi forming portion 14 is provided on the outer peripheral surface of the second needle 9. Is formed on the outer peripheral surface of the second needle 9.

  On the other hand, the inner peripheral surface of the second nozzle body 8 facing the venturi forming portion 14 is a cylindrical surface that is linear in the axial direction at least in the range from the upper portion of the venturi portion 13 to the lower portion of the venturi portion 13 (the inner peripheral surface is an axis). (Cylindrical surface that forms a straight line in the direction).

In the second embodiment, the fuel outlet of the pore 15 is provided immediately below the venturi portion 13 in the venturi forming portion 14 (the portion where the diameter expansion of the flow path is started).
By providing the fuel outlet of the pore 15 at this position (directly below the venturi section 13), after passing through the venturi section 13, it touches the pressurized air that flows straight along the gap of the venturi section 13. The fuel outlet of the pore 15 can be set at the position.
Even if it provides in this way, the effect similar to Example 1 can be acquired.

  In the above embodiment, the second injection hole 7 is arranged on the lower side (ground side) of the air blast injector so that the fuel supplied into the center hole 11 is guided toward the second injection hole 7 by gravity. However, the mounting direction of the air blast injector is not limited.

  In the above embodiment, the pressurized air does not pass through the second movable core 46, and the pressurized air is guided to the lower side of the second movable core 46 through the inside of the center hole 11 of the second needle 9 and the lateral hole 49. Although an example is shown, the supply path of the pressurized air is not limited, and a flow path and a groove part for guiding the upward pressurized air downward are formed in the inside or the outer periphery of the second movable core 46, and the first 2 The pressurized air may be guided to the lower air flow path 12 via the movable core 46.

  In the above embodiment, an example in which an air blast injector is used for a direct injection engine has been described. However, an injector that injects fuel into an intake passage (such as an intake port formed in a cylinder head) that supplies intake air into a cylinder is shown. An air blast injector to which the present invention is applied may be used.

  In the above-described embodiment, an example in which an electromagnetic actuator (first electromagnetic driving unit 6) is used as a driving unit for the first injector 1 is shown. However, the driving unit for the first injector 1 is not limited to an electromagnetic actuator. Other driving means such as a piezoelectric actuator may be used. Similarly, in the above-described embodiment, the example in which the electromagnetic actuator (second electromagnetic driving unit 10) is used as the driving unit of the second injector 2 is shown, but the driving unit of the second injector 2 is limited to the electromagnetic actuator. Instead, other driving means such as a piezoelectric actuator may be used.

DESCRIPTION OF SYMBOLS 1 1st injector 2 2nd injector 3 1st injection hole 4 1st nozzle body 5 1st needle 7 2nd injection hole 8 2nd nozzle body 9 2nd needle 11 Center hole 12 Air flow path 13 Venturi part 14 Venturi formation part 15 pores

Claims (5)

A first nozzle body (4) having a first injection hole (3) for injecting liquid fuel pressurized and supplied from the outside. The first nozzle hole (3) is accommodated in the first nozzle body (4). A first injector (1) comprising a first needle (5) for opening and closing
A second injection hole (7) for injecting liquid fuel injected from the first injector (1) together with air pressurized and supplied from the outside, and a second needle (9) for opening and closing the second injection hole (7) ), A second injector (2) comprising a second nozzle body (8) for accommodating the second needle (9);
In an air blast injector comprising:
(A) Inside the second needle (9), there is provided a center hole (11) to which the injected fuel of the first injector (1) is supplied,
(B) Between the second needle (9) and the second nozzle body (8), pressurized air enters the second injection hole (7) when the second injection hole (7) is opened. An air flow path (12) flowing toward the
(C) In the middle of the passage of the air flow path (12), a venturi section (13) for restricting the pressurized air flowing toward the second injection hole (7) when the second injection hole (7) is opened. A venturi forming part (14) is formed,
(D) The second needle (9) is provided with a pore (15) for sucking the liquid fuel in the center hole (11) into the pressurized air that has passed through the venturi section (13). ,
(E) An air blast injector characterized in that the fuel outlet of the pore (15) opens downstream of the venturi section (13). The air blast injector according to claim 1,
The venturi forming portion (14) bulges radially inwardly on the inner peripheral surface of the second nozzle body (8), thereby disposing the venturi portion (13) between the second needle (9). To form,
The fuel outlet of the fine hole (15) is the second needle (9) having the same diameter as the venturi part (13) between the venturi part (13) and the second injection hole (7). An air blast injector characterized by opening on the side surface of the air blast. In the air blast injector according to claim 1 or 2,
The fuel outlet of the fine hole (15) is 5 mm away from the end position of the venturi section (13) on the second injection hole (7) side and from the end position to the second injection hole (7) side. An air blast injector characterized by opening between the two positions. The air blast injector according to claim 1,
The venturi forming portion (14) bulges radially outward on the outer peripheral surface of the second needle (9), thereby forming the venturi portion (13) with the second nozzle body (8). Is what
The air blast injector characterized in that the fuel outlet of the fine hole (15) opens immediately below the venturi part (13) in the venturi forming part (14). In the air blast injector according to any one of claims 1 to 4,
The air blast injector, wherein the fuel outlet of the pore (15) opens in a flow velocity range in which the flow velocity of the pressurized air that has passed through the venturi section (13) exceeds Mach 1 due to a rubber nozzle effect.

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