JPH02204637A - Fuel injection valve - Google Patents

Abstract

PURPOSE:To secure good atomization without changing fuel pressure even in the case where a change area of supply fuel quantity is wide enough by installing a return passage which makes a cylinder, a needle valve, a swirling passage, a swirling slit and pressure at the upstream side of a control part act in the needle valve opening direction. CONSTITUTION:At the time of such a state that a request injection quantity is small, a return quantity is made much by control of a control valve 52 as a control part, and a needle valve 29 is seated on a hole part 26, fuel is swirled by a swirling passage 41 and a swirling slit 32 smaller in a total sectional area than the former, making it into a thin film, and it is sprayed out of a nozzle 27. When the request injection quantity is much and the return quantity is made smaller, the needle valve 29 is opened, and thereby the fuel comes to flow out at a taper part 31 even along not only the swirling slit 32 but also an outer circumferential surface of this taper part 31, but since the swirl takes place even in the swirling passage 42 large in the total sectional area, it is made into a thin film and sprayed out of the nozzle 27 likewise even at time of the injection quantity being much.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fuel injection valve for an engine, and more particularly to a fuel injection valve for a continuous combustion engine such as a gas turbine engine.

<Prior art> Conventional fuel injection valves of this type include those shown in Figs. Publication issue No. 239
Page-240, May 1980 8th Lecture on Liquid Atomization Lecture Paper r12. (Refer to ``Research on recirculation type swirl injection valve for EFI'').

That is, this is called a bypass injection valve, and the fifth
Referring to the figure, a roughly cylindrical fuel injection valve 10 receives fuel in a fuel tank from a base end side inlet 1, and part of it is injected into a combustor from a nozzle hole 2 at the tip, but the rest is It is returned into the fuel tank through the return port 3 in the side wall.

Specifically, a needle valve 6 is fitted so as to be movable back and forth into a substantially cylindrical cylinder 5 in which a tapered conical hole 4 is formed in the inner wall on the tip side and a nozzle hole 2 is formed in the tip. It's inserted. A tapered portion 7 is formed at the tip of the needle valve 6 so as to sit on the inner wall of the hole portion 4, and a turning slit 8 is further formed on the outer peripheral wall of the tapered portion.

Further, one end of a passage 9 for returning part of the fuel is open at the distal end surface of the tapered portion 7, and the other end is open as a return port 3 in the side wall.

This fuel injection valve 10 is connected as shown in FIG. In other words, the fuel in the fuel tank 11 is transferred to the constant pressure pump 1.
2, the supplied fuel is supplied from the inlet 1 to the fuel injection valve 10, and the supplied fuel is swirled through the swirling slit 8, and a part of the fuel is turned into a thin conical film by the swirling energy and is ejected from the nozzle hole 2. , the remainder passes through the passage 9 and further via the control valve 13 and is returned to the fuel tank 11 again.

The fuel involved in combustion is the fuel ejected from the nozzle hole 2, and this amount can be changed by adjusting the return amount using the control valve 13.

FIG. 7 shows the amount of fuel supplied from the fuel population (total flow) A with the pressure in the passage 9 (bypass pressure) on the horizontal axis when the fuel supply pressure is constant (high pressure: solid line, low pressure: broken line). , and the amount of fuel ejected from the nozzle hole 2 (nozzle flow) B on the vertical axis.

According to this, it can be seen that the lower the bypass pressure, the less the nozzle flow.

<Problems to be Solved by the Invention> However, in such a conventional fuel injection valve 10, since both the swirl slit 8 and the nozzle hole 2 are always kept at a constant area, the fuel injected from the nozzle hole 2 Even if the bypass amount is changed in order to change the amount, there is a problem in that the ratio between the minimum outflow amount and the maximum outflow amount of fuel ejected from the nozzle hole 2 cannot be expected to be more than about 1:5.

SUMMARY OF THE INVENTION In view of these conventional problems, an object of the present invention is to provide a fuel injection valve that can vary the amount of fuel over a wide range.

Means for Solving the Problems> To achieve the above object, the present invention provides a fuel injection valve that injects a required amount of fuel by giving swirl to fuel and returning a part of the swirled fuel. A nearly cylindrical cylinder with a tapered conical hole formed in the inner wall on the tip side and a nozzle hole at the tip, and a tapered cylinder fitted into the cylinder so as to be movable back and forth. a needle valve whose portion is seated on the inner wall of the hole; a swirl passage formed in the wall of the cylinder at an angle with respect to a radial line of the needle valve and supplying fuel around the proximal end of the tapered portion of the needle valve; A turning slit formed in the shape of a groove at an angle to the generatrix of the tapered part on either the outer circumferential wall of the tapered part of the needle valve or the inner circumferential surface of the hole in which it is seated, and having a total cross-sectional area smaller than the total cross-sectional area of the turning passage. and a return passage which has an opening in the distal end surface of the taper part, the return amount is controlled by a control part in the middle, and which applies pressure on the upstream side of the control part in the needle valve opening direction. .

According to the above configuration, when the required injection amount is small and the return amount is increased by the control of the control unit and the needle valve is seated in the hole, the fuel flows through the swirl passage and the total amount. It is swirled by a swirling slit with a small cross-sectional area, and is ejected from the nozzle hole in a thin film.

In addition, when the required injection amount is large and the return amount is reduced by control of the control valve, the needle valve opens and the fuel flows out not only through the swirl slit in the taber section but also along the outer circumferential surface of the taber section. However, since it is swirled in a swirling passageway with a large total cross-sectional area, even when the injection amount is large, it is ejected from the nozzle hole in a thin film.

<Example> An example of the present invention will be described below based on FIGS. 1 to 4.

The present embodiment is a fuel injection valve provided in a combustor in a gas turbine engine, and is used to mix injected fuel with air from a compressor to generate combustion gas.

Referring to FIGS. 1 to 3, the roughly cylindrical nozzle body includes a body 22 having a flange 21 for attaching a combustor, a cylinder 23 on its tip side, and a holder 24 on its outer circumferential side. It is integrated by 25.

A conical hole 26 with a tapered end and an orifice 27 are formed in the inner wall on the front end side of the cylinder 23 located at the center of the nozzle body.

Further, a slider 28 and a needle valve 29 integrally formed on the distal end side of the slider 28 are fitted into the hollow portion of the nozzle body so as to be movable back and forth, and are located within the cylinder 23 . Furthermore, a tapered part 31 is formed at the tip of the cylindrical part 30 of the needle valve 29, and a plurality of groove-shaped turning slits 32 are formed on the outer peripheral surface thereof at an angle to the generatrix thereof, as shown in FIG. (Four in this embodiment) are formed. Slider 28
The other end of a spring 34 fixed by an adjustable spring holder 33 is applied to the base end side, and the slider 28
The tapered portion 31 is seated in the hole 26 by urging it toward the distal end side.

Further, a fuel reservoir 35 is formed between the cylinder stepped portion 23a and the tip side of the slider 28, and a return passage 36 is formed that passes through the needle valve 29 and communicates the tip surface of the tapered portion 31 and the fuel reservoir 35. There is. Further, an outlet passage 37 and an outlet vibrator 38 are connected from the fuel reservoir 35 through the cylinder 23 and the body 22.

Further, as shown in FIG. 3, a circumferential groove 39 is formed on the outer periphery of the cylindrical portion of the needle valve 29, and an annular groove 40 formed on the outer periphery of the cylinder 23 opens toward the circumferential groove 39. 29
A plurality of turning passages 41 are arranged at an angle with respect to the radial direction line of (
In this embodiment, two of them are formed to penetrate the wall of the cylinder 23. Furthermore, an inlet passage 42 and an inlet vibe 43 that pass through the body 22, cylinder 23, and holder 24 are connected to the annular groove 40.

Note that the total cross-sectional area of the turning passage 41 is formed to be larger than the total cross-sectional area of the turning slit 32.

Further, the fuel in the fuel reservoir 35 is transferred to the slider 28 and the cylinder 23 through a passage 28a formed in the slider 28.
The liquid leaks onto the contact surface with the slider 28 and assists in smooth movement of the slider 28.

Further, the proximal ends of the artificial passageway 42 and the outlet passageway 37 are sealed with a blind plug 44 . Note that 45 and 46 are O-rings.

The fuel in the fuel tank 50 is fed into the fuel injection valve from the artificial vibrator 43 by the constant pressure pump 51, and is fed into the fuel injection valve through the inlet passage 42.
, a part of the liquid is ejected through the injection hole 27 through the annular groove 40, the turning passage 41, the circumferential groove 39, and the turning slit 32.

At this time, the fuel is swirled in the swirl passage 41 and the swirl slit 32, and a thin conical fuel is ejected from the nozzle hole 27.

The remaining fuel that has come out of the turning slit 32 passes through the return passage 36 from the opening at the tip end of the tapered part 31 to reach the fuel reservoir 35, and then passes through the exit passage 37 and the exit vibe 38 to the outside of the fuel injection valve. Get out.

The fuel is then returned to the fuel tank 50 via a control valve 52 serving as a control unit that adjusts the pressure of the returned fuel. The control valve 52 is duty-controlled.

Note that the leaked fuel that has assisted the movement of the slider 28 is returned into the fuel tank 50 through the hollow part of the fuel injection valve.

Here, a return passage 36, a fuel reservoir 35, an outlet passage 37
, the outlet vibrator 38, and the control valve 52 constitute a return passage.

Moreover, the fuel in the circumferential groove 39 does not directly flow into the fuel reservoir 35 due to the effect of the labyrinth seal 53 provided on the outer peripheral wall of the needle valve 29.

Here, the fuel pressure in the fuel reservoir 35 is adjusted by the valve opening time ratio (duty ratio) of the control valve 52, and this fuel pressure pushes the needle valve 29, which is integrated with the slider 28, toward the proximal end, and the slider 28 It is designed to compete with the spring 34 acting on the proximal end side.

In other words, when the required injection amount is small and the opening time ratio of the control valve 52 is large, the pressure in the fuel reservoir 35 is low, and the slider 28 is pressed to the right by the spring 34, so that the turning passage 41 The fuel passing through is swirled more strongly by the swirl slit 32 having a smaller total cross-sectional area.

A part of the fuel that has passed through the swirl slit 32 is then transferred to the nozzle hole 2.
7, it is ejected in a conical shape due to the swirling energy and becomes atomized, and the remainder passes through the return passage 36 and reaches the fuel reservoir.

Further, when the required injection amount is large and the valve opening time ratio of the control valve 52 is small, the pressure in the fuel reservoir 35 increases, so
The slider 28 moves to the left against the tension of the spring 34,
Since the fuel that has passed through the swirl passage 41 flows out along the outer wall of the tapered portion 31 other than the swirl slit 32, the swirl force applied at the swirl slit 32 is reduced. but,
Since the resistance in the swirl slit 32 is reduced and the passage area is increased, the amount of fuel flowing in from the inlet vibrator 43 by the constant pressure pump 51 increases, the flow velocity in the swirl passage 41 increases, and this portion also allows for sufficient swirl. Power is given.

Therefore, the fuel ejected from the nozzle hole 27 is also formed into a thin film and becomes atomized.

At this time, since the amount of fuel supplied to the fuel injection valve is increasing, the amount of fuel from the nozzle hole 27 also increases.

The above flow rate characteristics are shown in FIG.

According to this, until the slider 28 movement start pressure (P) is reached, the supply amount (total flow) and the injection amount (nozzle flow) are expressed as functions of the return side pressure (bypass pressure) as in the conventional example.

When the pressure at which the slider 28 starts moving is reached, the supply amount rapidly increases because the rotation slit 32 is no longer restricted while the supplied fuel pressure remains constant.

However, since the returned fuel amount does not change much, the subtracted injection amount also increases dramatically.

Finally, when the pressure on the fuel reservoir side reaches a certain level and the area increase effect caused by the movement of the slider 28 is saturated, the supply amount and injection amount are determined by the balance between the opening time ratios of the nozzle hole 27 and the control valve 52. It becomes like this.

It can be said that the characteristics when the bypass pressure is high in FIG. 4 are those of a fuel injection valve with a large flow rate compared to when the bypass pressure is low.

For these reasons, when the needle valve 29 is seated in the hole 26 under the control of the control valve 52, the fuel is swirled by the swirl passage 41 and the swirl slit 32, which has a smaller total cross-sectional area. When the needle valve 29 is moving in the opening direction,
Fuel flows out not only from the swirl slit 32 in the tapered portion 31 but also along the outer circumferential surface of the tapered portion 31, but since the fuel is swirled in the swirl passage 41, which has a large total cross-sectional area, it is similarly thinned and flows out from the nozzle hole 27. More erupts.

Therefore, the amount of injected fuel can be varied over a wide range.

<Effects of the Invention> As explained above, according to the present invention, the swirl slit that gives swirl to the fuel can be opened and closed, and the swirl passage that has a larger total cross-sectional area and also gives swirl to the fuel is provided upstream of the swirl slit. A portion of the fuel is returned without being ejected downstream of the swirl slit, and the pressure of the returned fuel is used to open and close the swirl slit.When the amount of injection is small, the swirl slit is A swirl can be applied in the slit, and when the amount of ejection is large, a swirl can be applied mainly in the swirl passage.

Therefore, even when the range of variation in the amount of fuel supplied is wide, such as in a fuel injection valve used in a combustor for an automobile engine, it is possible to obtain a good spray without changing the supplied fuel pressure. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a fuel injection valve showing an embodiment of the present invention, FIG. 2 is a view of the tapered portion seen from the tip side, and FIG. FIG. 4 is a flow rate characteristic diagram of the fuel injection valve of this embodiment, FIG. 5 is a sectional view of a conventional fuel injection valve, FIG. 6 is a connection diagram of the fuel injection valve, and FIG. 7 is a flow rate characteristic diagram. 23... Cylinder 26... Hole 27...
Nozzle hole 28...Slider 29...Needle valve 3
1...Tapered part 32...Swivel slit 35...
・Fuel reservoir 36...Return passage 37...Outlet passage 38...Outlet vibe 41...Swivel passage 51...Constant pressure pump 52...Control valve

Claims (1)

[Scope of Claims] A fuel injection valve that injects a required amount of fuel by swirling the fuel and returning a portion of the swirled fuel, the fuel injection valve having a tapering conical hole in the inner wall on the tip side. a substantially cylindrical cylinder with a nozzle hole formed at its tip, a needle valve that is fitted into the cylinder so as to be movable back and forth and whose tapered tip is seated on the inner wall of the hole, and a wall of the cylinder. a swirling passage formed at an angle with respect to the radial direction of the needle valve and supplying fuel around the proximal side of the tapered part of the needle valve; and an outer circumferential wall of the tapered part of the needle valve or an inner circumferential surface of the hole in which it is seated. A rotating slit is formed in a groove shape at an angle with respect to the generatrix of the tapered part, and has an opening at the tip surface of the tapered part, and has a total cross-sectional area smaller than the total cross-sectional area of the rotating passage, and has an opening on the tip surface of the tapered part, 1. A fuel injection valve characterized by having a return passage whose return amount is controlled by the control part and which causes pressure upstream of the control part to act in the needle valve opening direction.