JPH0730935Y2 - Fuel injector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a fuel injector used in, for example, an internal combustion engine for an automobile, and more particularly to a fuel injector of a type that atomizes injected fuel by using assist air.

[Conventional technology]

FIGS. 6 and 7 show a fuel injector of this type according to the prior art. In the figure, 1 is an injector main body having an electromagnetic actuator provided therein, 2 is an injection nozzle projectingly provided on the axial front end side of the injector main body 1, and a fuel injection hole 2A is formed at the front end thereof, and 3 is the injection nozzle. A needle valve provided in a state where a pin-shaped pintle 3A is projected outside from the fuel injection hole 2A in the nozzle 2, or a valve body composed of a poppet valve, the valve body 3 being operated by an electromagnetic actuator, Injection control.

Reference numeral 4 denotes a cylindrical agitator that is inserted from the outside of the injection nozzle 2 to the injector body 1, and the agitator 4 has a cylindrical fitting portion 4A that fits into the injector body 1 and an inner diameter of the injection nozzle 2. A hollow cylindrical guide portion 4B which is formed to have a slightly larger diameter, has an axial length that projects in the axial direction from the tip of the injection nozzle 2, and has an open tip.
Female screw 4C engraved on the inner circumference of the distal end side of the tubular guide portion 4B
And an air blowing port 4D formed between the tubular fitting portion 4A and the tubular guide portion 4B and formed as an opening. The agitator 4 is assembled with the tubular fitting portion 4A fitted to the injector body 1, and communicates with the air blowing port 4D between the injection nozzle 2 and the tubular guide portion 4B. An annular flow path 5 is formed. Further, an air supply pipe 6 that guides air on the outside air side into the annular flow path 5 at the time of idling is connected to the air blowing port 4D.

Reference numeral 7 denotes a scoop-shaped air ejection hole forming member screwed to the cylindrical guide portion 4B of the agitator 4, and the air ejection hole forming member 7
Is a hollow cylindrical part 7B with a small diameter whose center is the fuel outlet 7A,
Is protruding from the hollow tubular portion 7B in the axial direction, and the flare tube portion 7C having a vertical front end surface 7C ₂ inside inclined surface 7C ₁ and axis diameter increases gradually along the axial direction, the enlarged-diameter tubular portion It is integrally formed with a male screw 7D formed on the outer peripheral surface of the tip side of 7C, and the inside of the air ejection hole forming member 7 is a substantially conical mixing chamber 8.

, 9 are a plurality of air ejection holes formed in the expanded diameter cylindrical portion 7C of the air ejection hole forming member 7, and the axis of each air ejection hole 8 is from the outer surface of the expanded diameter cylindrical portion 7C. It is inclined in the circumferential direction toward the inner inclined surface 7C ₁ so that the assist air B is jetted in the tangential direction of the injected fuel A scattered in the mixing chamber 8 in a conical shape.

The conventional technique is configured as described above, and the operation of injecting fuel will be described next.

Fuel is supplied into the injection nozzle 2 at a predetermined fuel pressure. When an electromagnetic actuator in the injector body 1 is excited by an injection signal from a control unit (not shown) and the valve body 3 in the injection nozzle 2 is attracted in a direction to open the fuel injection hole 2A, the fuel in the injection nozzle 2 is injected. Is injected from the fuel injection hole 2A to the outside.

On the other hand, during idling, the inside pressure of the intake manifold becomes negative, so that the air sucked into the annular flow path 5 from the outside air side through the air supply pipe 6 enters the mixing chamber 8 through each air ejection hole 9. It is blown out as assist air B in the tangential direction of the injected fuel A. As a result, the injected fuel A flows as a swirling flow in the mixing chamber 8 and is mixed with the assist air B during this period and atomized into fine particles.

By atomizing the injected fuel A with the assist air B as described above, the rotational fluctuation during idling is reduced and the idling stability is improved.

[Problems to be solved by the invention]

Thus, in the prior art, the air ejection hole 9 for the assist air B is formed in front of the fuel injection hole 2A of the injection nozzle 2 in the injection direction and toward the inside of the mixing chamber 8. Therefore, the injected fuel A injected from the fuel injection hole 2A into the mixing chamber 8 adheres to the inner inclined surface 7C ₁ of the air injection hole forming member 7 by the assist air B so as to be sprayed. Then, the fuel adhering to the inner inclined surface 7C ₁ gradually becomes an oil droplet A ′, flows down to the tip surface 7C ₂ side and stays there, and then falls into the intake manifold, resulting in a rapid air-fuel ratio. However, there are drawbacks such as a change in the rotation speed during idling and an increase in exhaust gas concentration.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and it is possible to atomize the injected fuel by the assist air, and prevent the injected fuel from dropping into oil droplets and improving the idle stability. It aims at providing the fuel injector which was made into.

[Means for solving problems]

Means for Solving the Problems The present invention, which is configured to solve the above-mentioned problems, includes an injection nozzle projecting from an injector body and having a fuel injection hole formed at a tip thereof to be opened and closed by a valve body, and an outer circumference of the injection nozzle. Has a cylindrical guide member that is inserted into the injection nozzle and guides assist air to the tip end side of the injection nozzle, and an opening into which the tip end side of the injection nozzle fits, and the tip end surface is the fuel injection hole opening end of the injection nozzle. An air ejection hole forming member provided on the front end side of the cylindrical guide member so as to be located on the same plane or rearward in the injection direction, and a fuel injection hole of the injection nozzle formed in the air ejection hole forming member. And an air ejection hole for ejecting the assist air in the tangential direction of the fuel injected in a conical shape.

[Action]

The tip surface of the air ejection hole forming member is disposed on the same plane as the fuel injection hole opening end of the injection nozzle or at the rear of the injection direction. Therefore, the injected fuel diffused when the assist air is blown It is possible to prevent the phenomenon that the atomized fuel is atomized without adhering to the tip end surface of the air ejection hole forming member, and the injected fuel drops.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5.

1 and 2 show a first embodiment of the present invention, in which the fuel injector is a needle valve type. In the figure, 11 is a cylindrical injector main body having a built-in electromagnetic actuator, 12 is an injection nozzle that is provided on the injector main body 11 so as to project in the axial direction, and has a large-diameter cylindrical portion 12A and a small-diameter tip portion 12B on the tip side. A fuel injection hole 12C is provided in the small-diameter tip portion 12B.
Are formed. A needle valve 13 is axially movably provided in the injection nozzle 12 with a pintle 13A protruding outward from a fuel injection hole 12C.

Reference numeral 14 denotes a cylindrical guide member fitted from the tip of the injector body 11 to the outer periphery of the injection nozzle 12, and the guide member 14 is a cylindrical fitting portion 14A fitted to the injector body 11.
And a hollow cylindrical guide portion whose inner diameter is formed to be slightly larger than the outer diameter of the injection nozzle 12 and whose front end surface has an axial length that is flush with the small diameter front end portion 12B of the injection nozzle 2.
14B and an air blowing port 14C that is formed between the tubular guide portion 14B and the tubular fitting portion 14A, and is integrally formed between the tubular guide portion 14B and the injection nozzle 12. An annular flow path 15 communicating with the air blowing port 14C is formed therein.
An air supply pipe 16 that guides the outside air into the annular flow path 15 at the time of idling is connected to the air blowing port 14C.

Reference numeral 17 denotes a circular flat plate-shaped air ejection hole forming member fitted to the tip end side of the guide member 14, and a stepped fitting hole 17C is formed at the center of the air ejection hole forming member 17 from an upper surface 17A to a lower surface 17B.
Are formed. The fitting hole 17C is fitted with the small diameter tip portion 12B from the tip of the large diameter cylinder portion 12A of the injection nozzle 12, and the end face of the small diameter tip portion 12B where the fuel injection hole opens and the air ejection hole forming member. The lower surface 17B of 17 has the same surface.

, 18, are four air ejection holes formed in the air ejection hole forming member 17 at intervals of 90 degrees in the circumferential direction, and each of the air ejection holes 18 is formed on the upper surface 17A of the forming member 17. By forming the inflow port 18A side that opens and the outflow port 18B side that opens in the lower surface 17B by shifting in the circumferential direction, the axis of the air ejection hole 18 is the tangent line of the injected fuel A that is conically injected from the fuel injection hole. Is oriented.

In the figure, 19 is interposed between the fitting hole 17C of the air ejection hole forming member 17 and the injection nozzle 12 in order to prevent the air supplied into the annular flow path 15 from leaking to the fuel injection hole side. Dressed O
It's a ring.

The present embodiment is configured as described above, and the electromagnetic solenoid in the injector body 11 opens the needle valve 13 to inject the fuel from the fuel injection hole of the injection nozzle 2, and the pintle 13A causes the fuel to flow from about 28 to 40. There is no difference from the prior art in that the light is diffused into a conical shape within a range of degrees.

Thus, according to the present embodiment, the air ejection hole forming member 17 is formed by a flat plate body whose lower surface 17B is located on the same plane as the opening end of the fuel injection hole 12C of the injection nozzle 12, The conical mixing chamber 8 is not provided, and each air ejection hole 18 has a flat lower surface 17B of the forming member 17.
It is formed by opening it. Even with this configuration, the assisted air B is injected from each air ejection hole 18 into the injected fuel A that is injected from the fuel injection hole, collides with the pintle 13A, and diffuses into a conical shape.
2 is sprayed in the tangential direction as shown by the arrow in FIG. 2, the injected fuel A is swirled by the assist air B and is mixed and atomized while flowing as a swirling flow.

In addition, since the mixing chamber 8 is not provided in front of the air ejection hole 18 in the ejection direction as described above, the injected fuel A sprayed with the assist air B remains in the atomized state without forming oil droplets. Since it scatters in the teach manifold, it is possible to completely eliminate the fuel drop phenomenon that has occurred in the prior art.

Next, FIGS. 3 and 4 show a second embodiment of the present invention. The same components as those of the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

The feature of this embodiment is that the air ejection hole 1
A plurality of air ejection holes 21 having a smaller diameter than the air ejection holes 18 are provided in the circumferential direction on the outer peripheral side of the air ejection hole forming member 17 so as to surround 8, 18 ,.

According to the present embodiment having the above-described structure, a part of the air supplied from the outside air side into the annular flow path 15 through the air supply pipe 16 at the time of idling is ejected from each air ejection hole 18 to assist air B. The remaining part is the injection nozzle from each air outlet hole 21.
An air curtain C that blows out in the axial direction of 12 and surrounds the conical injected fuel A in a cylindrical shape is formed.

As a result, the injected fuel A that has been conically injected from the injection nozzle 2 is surrounded by the air curtain C, so that even if the assist air B is sprayed from the tangential direction, the injected fuel A diffuses to the surroundings. As a result, a swirling flow occurs in the air curtain C, so that the air can be sufficiently mixed with the assist air and atomization can be promoted.

In each of the above embodiments, the lower surface 17B of the air ejection hole forming member 17 is located on the same plane as the end surface of the small diameter tip portion 12B of the injection nozzle 12, so that the fuel injection hole 12C and the air ejection hole 1
Although 8 has been described as opening on the same plane, as shown in FIG. 5, the end surface of the small diameter tip portion 12B of the injection nozzle 12 is projected to the lower surface 17'B of the air ejection hole forming member 17 '. By doing so, the air ejection hole 18 may be located rearward in the injection direction with respect to the opening end of the fuel injection hole 12C.

Further, in each of the embodiments, four air ejection holes 18 are described in the air ejection hole forming member 17, but the number and the diameter of the air ejection holes 18 can be appropriately selected. Further, the number of the air blow-out holes 21 for forming the air curtain C is not limited to the embodiment, of course, and an arc-shaped blow-out port may be formed instead of the round hole.

[Effect of device]

The present invention has been described in detail above, and since the tip surface of the air ejection hole forming member is configured to be located on the same plane as the opening end of the fuel injection hole of the injection nozzle or rearward in the injection direction, Similar to the technology, the injected fuel can be atomized by the assist air, and the mixing chamber, which caused the injected fuel to drop into oil drops, can be eliminated, resulting in stable idle speed stability. It can be improved and the phenomenon that the exhaust gas concentration becomes high can be prevented.

[Brief description of drawings]

1 and 2 relate to a first embodiment of the present invention.
FIG. 1 is a longitudinal sectional view of a main part of a fuel injector, FIG. 2 is a bottom view of FIG. 1, FIGS. 3 and 4 are related to a second embodiment of the present invention, and FIG. 3 is a main part of the fuel injector. FIG. 4 is a vertical cross-sectional view, FIG. 4 is a bottom view of FIG. 3, FIG. 5 is a vertical cross-sectional view of a main part of a fuel injector according to a third embodiment of the present invention, and FIGS. 6 is a longitudinal sectional view of a main part of the fuel injector, and FIG. 7 is a partially enlarged view of FIG. 11 ... Injector body, 12 ... Injection nozzle, 12C ... Fuel injection hole, 14 ... Cylindrical guide member, 17 ... Air injection hole forming member,
17B, 17'B ... Outer surface, 18 ... Air ejection hole, A ... Injection fuel, B
… Assist air.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Osamu Sakurai, 1671 Kasukawa-cho, Isesaki-shi, Gunma 1 1 Nippon Electric Equipment Co., Ltd. Co., Ltd. (72) Inventor, Masaru Kurihara, 1671 Kasukawa-cho, Isesaki-shi, Gunma Nippon Electric Equipment Co., Ltd. (56) References , U) Actual development Sho 59-172267 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. An injection nozzle (12) projecting from an injector main body (11), having a fuel injection hole (12C) opened and closed by a valve body (13) at its tip, and the injection nozzle (12). A cylindrical guide member (14) which is inserted into the outer periphery of the injection nozzle (12) and guides the assist air (B) to the tip side of the injection nozzle (12), and an opening (17C, 17'C)
And the cylindrical guide member (14) such that the tip surface (17B, 17'B) is located on the same plane as the fuel injection hole (12C) opening end of the injection nozzle (12) or behind the injection direction. ) Air ejection hole forming members (17, 17 ') provided on the tip side of
And the assist in the tangential direction of the injected fuel (A) which is provided in the air ejection hole forming member (17, 17 ') and is conically injected from the fuel injection hole (12C) of the injection nozzle (12). A fuel injector including an air ejection hole (18) for ejecting air (B).