JPH0583806B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fuel injection valve used in a continuous combustion device such as a gas turbine engine.

BACKGROUND ART Fuel injection valves for combustors such as gas turbines that include swirl chambers are known. Although this type of fuel injection valve has good atomization characteristics, a certain level of pressure, ie, flow rate, to the swirl chamber is required for atomization. Conversely, this means that it is not applicable when the pressure or flow rate to the swirl chamber is low. In order to improve the characteristics of a fuel injection valve equipped with a swirl chamber at low flow rates, it is conceivable to connect the swirl chamber to a return pipe through a throttle. That is, the difference between the amount of fuel entering the swirl chamber and the amount of fuel being returned is the actual injection amount. That is, the amount of fuel that is returned is added to the amount of fuel that enters the swirl chamber. Therefore, the fuel pressure will increase by that amount,
Sufficient vortex strength can be obtained in the vortex chamber,
As a result, it is possible to improve spray characteristics at low flow rates. However, simply returning some fuel from the swirl chamber does not provide control over a wide range of flow rates and wastes energy at high flow rates.

Purpose of the Invention The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel injection valve that can obtain good spray characteristics over a wide flow rate range while suppressing wasteful energy consumption. be.

Structure of the Invention The fuel injection valve of the present invention includes a first swirl chamber with a small volume connected to a fuel supply pump and a second swirl chamber with a large volume, and the second swirl chamber and the fuel supply pump are connected to each other. A control valve is provided that opens when the fuel pressure is above a predetermined value and guides the fuel to the second swirl chamber, and the first swirl chamber and the second swirl chamber each have a nozzle for injecting fuel. Only the first swirl chamber is provided with a relief hole at a position opposite to its nozzle, and the fuel return passage from the relief hole is throttled in the middle, and the throttle is connected to the pressure of the first swirl chamber. The valve has a needle that opens and closes accordingly, and includes a non-return valve that is biased to close the relief hole by a weak spring between the needle and the relief hole, and is opened by the fuel pressure in the first swirl chamber. ing.

Operation When the fuel pressure does not reach a predetermined value, the control valve is closed, so fuel is supplied from the fuel supply pump only to the first swirl chamber, which has a small volume, and fuel is injected from this first swirl chamber. However, at this time, part of the fuel introduced into the first swirl chamber from the fuel supply pump is returned from the fuel return passage.

On the other hand, after the fuel pressure reaches a predetermined value, the control valve is opened, and fuel is also supplied from the fuel supply pump to the second vortex chamber, which has a large volume, so that the necessary amount of fuel can be injected. Since the second swirl chamber is not provided with a return passage, no fuel is returned from this second swirl chamber.

The needle throttles the orifice in response to an increase in pressure in the first swirl chamber, and the amount of returned fuel is gradually reduced as the fuel pressure increases.

The anti-reflux valve prevents backflow of fuel from the first swirl chamber.

Embodiment An embodiment will be described below. In FIG. 1, reference numeral 1 denotes a fuel injection valve, which is attached to a wall surface 2 of a combustion chamber of a gas turbine engine. Fuel from the fuel tank 3 is introduced into a flow control device 5 by a pump 4. The flow rate control device introduces fuel into the fuel injection valve 1 via the pipe 6 at a pressure (flow rate) depending on the operating conditions of the engine. 7 returns excess fuel to the tank with a return pipe.

FIG. 2 specifically shows the structure of the fuel injection valve 1 of the present invention. The embodiment shown in Fig. 2 has two large and small vortex chambers, and when the flow rate is small, the injection is received by the smaller vortex chamber, and when the flow rate is large, the injection is received by this vortex chamber and the larger vortex chamber. I try to have it. In the figure, 10 is a main body, and 12 is a nozzle holder. The nozzle holder 12 has a cylindrical shape,
Vortex holder 14, vortex plate 16, valve body 18, and valve plate 2
0s are inserted sequentially. In this inserted state, the main body 10 is inserted into the nozzle main body 12 via the O-ring 22, and the outer cylinder 24 brings them into a mutually fastened state.

As shown in an enlarged view in FIG. 3, a first vortex chamber 26 is formed between the vortex plate 16 and the valve body 18, and below the first vortex chamber 26, the vortex plate 16 and the vortex holder are connected. 14, a second swirl chamber 28 is formed between the two. The first swirl chamber 26 opens into a second swirl chamber 28 by a first jet orifice 30 . Also, the second
The vortex chamber opens into the combustion chamber of the gas turbine engine by a second jet orifice 32 . The first nozzle 30 is located above the second nozzle 32 so as to face it.

In FIG. 1, 34 is a fuel supply connector 36
and a fuel return connector 38, and a cap 40 connects O-rings 41, 4.
1' to the main body 10. The cap 40 includes a cylindrical portion 401 that is fitted into the hole 101 of the main body 10, and a backflow prevention valve 42 is installed within the cylindrical portion 401. This check valve 42 is formed as a ball valve and is disposed between a valve seat 44 fitted into the cylindrical portion 401 and a spring seat 46. The spring 48 exerts a biasing force that causes the valve 42 to close the valve seat 44 at all times. The valve hole of the valve seat 44 communicates with the fuel hole 361 of the fuel supply connector 36 via a vertical hole 402 and a horizontal hole 403 in the cap 40. The combustion chamber 50 formed downstream of the check valve 42 is
A passage 102 in the main body 10, an annular passage 52 between the main body 10 and the nozzle holder 12, an annular passage 54 between the valve body 18, the valve plate 20 and the nozzle holder 12, a fuel hole 181 in the valve body 18, a valve body 18 and the vortex plate 16. through an annular passageway 56 between and a first inlet 58.
It opens into a swirl chamber 56 (see FIG. 3).

In FIG. 2, 60 is a control valve, which is configured as a ball valve. The control valve 60 is connected to the valve plate 2 by an adapter 64 which receives the force of a spring 62.
The valve seat 202 is biased to sit on the valve seat 202 formed at 0. The valve hole in the valve seat 202 opens into the annular passage 54 through a hole 204 in the valve plate 20 and receives fuel supply therefrom. The space 66 above the valve seat includes a passage 206 in the valve plate, a fuel passage 184 in the valve body 18, a passage 161 in the vortex plate 16, an annular passage 67 between the vortex plate and the vortex holder, and a second inlet. It opens into the second swirl chamber 28 via 70 (see FIG. 3).

A first inlet 58 into the first swirl chamber 26 opens tangentially thereto, as schematically shown in FIG.
Similarly, the second inlet 70 to the second swirl chamber 28 is also open tangentially. It is well known that such a tangential opening of the inlet into the swirl chamber results in a swirling flow in the swirl chamber.

According to the present invention, the relief hole 185 is provided in the wall surface of the vortex chamber 26, which takes charge of injection when the flow rate is small, on the side opposite to the injection port. Relief hole 18
5 is bored in the vortex plate 16 and returns some of the fuel from the vortex chamber 26 as described below. By installing it on the side opposite to the nozzle 26, part of the fuel can be returned without affecting the swirling flow within the swirl chamber 26 in the slightest. The swirl chamber 26 has a relief hole 185 and a valve body 18.
Bore 187 inside, throttle member 74, hole 207 inside valve plate 20, main body 10 and valve plate 2
an annular passage 76 between 0 and 10 in the body 10;
5, 106, and a vertical hole 381 and a horizontal hole 382 in the fuel return connector 38, the fuel return connector 38 is connected to the pipe 7 in FIG. The bore 187, the orifice 741 of the throttle member, the hole 207, the annular passage 76, the passages 105, 106, the holes 381, 382, and the pipe 7 constitute the fuel return passage of the present invention. Third
As shown in the figure, the throttle member 74 has a cylindrical shape and is threaded into a thread 187A within the bore 187. The aperture member 74 has a hexagonal hole 740 at one end.
By inserting a tool here and turning it, you can adjust the return amount as described below. The throttle member 74 has an orifice 741 at the other end. A needle 75 is provided so as to face this orifice. The needle 75 is biased away from the orifice 741 by a spring 76. The communication hole 185 that opens into the first swirl chamber 26 is equipped with a second non-return valve 80 , and this valve 80 has a valve seat 188 adjacent to the communication hole 185 that is closed by a very weak spring 77 whose upper end abuts against the needle 75 . It exerts an urging force that constantly blocks it.

To describe the operation of the device of the present invention described above, when the device is stopped, the first check valve 42 closes the valve seat 44 by the force of the spring 48, while the spring 7
A downward force is applied to the second check valve 80 by the force 7, and the valve seat 1 near the opening 185 is
Block 88. This prevents fuel from dripping out of the nozzle when stopped.

When the device starts operating, fuel from the pump 4 and then the flow control device 5 is introduced from the pipe 6 to the fuel supply connector 36 of the fuel injection valve 1, and the check valve 42 is pushed open through the passage 361 and holes 403 and 402.
Enter the fuel chamber 50. The fuel from the chamber 50 flows through the passage 1
02, 52, 54, 181, 56 and is introduced tangentially into the first swirl chamber 26 through the first inlet 58, producing a swirling flow therein. The swirling fuel flow flows from the first nozzle 30 to the second nozzle 3.
2 and is sprayed into the combustion chamber in the form of a thin, conical liquid film. When the conical liquid film formed thin in this way reaches a certain flight distance, it becomes finely atomized. The spray from the first vortex chamber 26 is responsible for spraying when the pressure of the fuel from the flow control device 5 is low, that is, in the low flow region, and its flow rate characteristics are determined by the inlet pressure (i.e., from the flow control device 5). (fuel pressure) p is expressed by the solid line l ₁ in FIG. Note that in this pressure state, the fuel pressure acting on the control valve 60 is small, so it closes and the second
No fuel is supplied to the vortex chamber 28 of. In this low flow rate region, the pressure of the fuel supplied into the first swirl chamber 26 acts on the check valve 80 and pushes it open from the valve seat 188 against the spring 77. on the other hand,
At this pressure, the spring 76 is set so that the needle 75 does not move, ie, opens the orifice 741. That is, the first swirl chamber 26 is
Relief hole 185, orifice 741, passage 20
7, 105, 106, and the return pipe 7 via holes 381, 382. The return flow rate at this time is determined by the diameter of the orifice 741. As described above, since fuel is always flowing out from the first swirl chamber 26, the desired injection amount from the nozzle 30 cannot be obtained unless the flow rate introduced into this chamber 26, that is, the pressure p is increased. There will be no. As a result, sufficient swirling flow strength can be achieved in the swirl chamber 26 even in a region where the injection amount is small, and sufficient atomization can be achieved even in this region. Unlike the present invention, when such a return piping system is not installed, the spray amount characteristics from the first swirl chamber 26 are as shown in FIG.
m ₁ street. By installing a return piping system for the same spray amount, the swirl chamber inlet pressure can be increased. This allows good atomization to be maintained at low flow rates.

When the pressure in the first swirl chamber 26 reaches p ₁ in FIG. Therefore, the needle 75 is lifted, and the opening area of the orifice 741 is gradually reduced in accordance with the increase in pressure in the swirl chamber. Therefore, the amount of returned fuel gradually decreases. Since the amount of returned fuel decreases as the pressure increases, the injection amount gradually approaches the characteristic m ₁ when there is no orifice, as indicated by x in FIG. 5. At the time of pressure p ₂ , the needle 75 completely closes the orifice 741, and as a result, the amount of returned fuel becomes zero, and the injection amount characteristics become
m ₁ .

When the fuel pressure reaches the set value _p3 , the fuel pressure acting on the control valve 60 overcomes the spring 62, causing the valve 60 to move away from the valve seat 202 and the fuel flowing into the passages 206, 184, 1.
61 and 67 to a second inlet 70, from which it is introduced tangentially into the second swirl chamber 28. Therefore, the second swirl chamber 28
In addition to the injection from the first swirl chamber 26, the flow rate characteristic is represented by m ₂ in FIG. In the present invention, in the same figure,
From flow rate Q ₁ at minimum pressure pmin to Q ₂ at maximum pressure
A wide range of flow rate changes can be obtained. When l ₁ and l ₂ shown by the two-dot chain lines in the figure are the orifice 741 fixed aperture, the one-dot chain lines m ₁ and m ₂ are the orifice 741.
This is the characteristic when no fuel recirculation is installed, that is, when fuel recirculation is not performed. In the low flow range, a small flow rate equivalent to that with a fixed orifice (l ₁ ) can be obtained, and in the high flow range, a large flow rate equivalent to that without an orifice (m ₂ ) can be obtained.

In the second embodiment shown in FIG.
An adjuster 90 is screwed into the thread 187A of the bore 187 below the adjuster 90.
The lower end of the needle 75 is in contact with the upper end of the needle 75. The adjuster 90 also serves as a seat for the return spring 77. The adjuster 90 has an opening 901 in the center.
and the lower end flange 7 of the needle 75
52 has a groove 752A, which allows the return oil to flow smoothly when the needle 75 is closed. In this embodiment, by adjusting the adjuster 90, the initial lift of the needle 75, that is, the pressure _p1 shown in FIG. becomes.

In the present invention, as shown in the graph of FIG. 5, in the low flow rate range, the diameter of the orifice is changed by the needle according to the pressure of the vortex chamber, and this compares with the case where the orifice is not variable. The flow rate range in the low flow rate region can be widened.
In addition, as in the example, when two large and small vortex chambers are used together, the switching from the l ₁ characteristic to the m ₁ characteristic is p ₁
This occurs smoothly between the pressures from p2 to _p2 , and the sudden change in flow rate that would occur if switching was made at switching point _p3 is suppressed. Furthermore, by installing a spring 77 that closes the check valve 80, it is possible to prevent fuel from dripping regardless of the mounting orientation of the fuel injection valve.

Effects of the Invention Two swirl chambers, a first swirl chamber and a second swirl chamber, are provided, and the supply of fuel to the second swirl chamber is controlled by a control valve that opens when the fuel pressure is higher than a predetermined value. In addition, the fuel is returned only from the first swirl chamber through the relief hole. Therefore, when the fuel flow rate is low, fuel is injected from the first vortex chamber and the fuel is returned to increase the pressure in the first vortex chamber, improving atomization by increasing the flow rate, and increasing the flow rate. By injecting fuel from the second vortex chamber during operation with a large amount of fluid, it is possible to inject the desired amount of fuel, and since there is no return of fuel from the second vortex chamber, the fuel supply pump The effect is that the necessary flow rate can be obtained without increasing the output so much. In addition, since it is equipped with a needle that controls the return amount, it is possible to obtain a good fuel atomization state over a wide flow rate range. This has the effect of smoothing the transition between the flow rate region and the high flow rate region where injection is also performed from the second swirl chamber. Further, by providing a check valve that biases the relief hole to close with a weak force, backflow of fuel from the return passage to the relief passage can be avoided.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic configuration diagram of a device including a fuel injection valve of the present invention, FIG. 2 is a detailed sectional view of the fuel injection valve in FIG. 1, FIG. 3 is a partially enlarged view of FIG. 1, and FIG. 4 is a plan view of the swirl chamber, FIG. 5 is a flow characteristic diagram of the fuel injector of the present invention, FIG. 6 is a partially detailed enlarged view of the second embodiment, and FIG. 7 is taken along the - line in FIG. 6. ,
Bottom view of the needle. 1...Fuel injection valve, 7...Return pipe, 26,
28... Vortex chamber, 30, 32... Nozzle, 74...
Throttle member, 77... spring, 80... backflow prevention valve.

Claims (1)

[Claims] 1 Equipped with a first vortex chamber with a small volume connected to a fuel supply pump and a second vortex chamber with a large volume, the fuel pressure is greater than a predetermined value between the second vortex chamber and the fuel supply pump. A control valve is provided that opens when the valve is opened and guides the fuel to the second swirl chamber, and the first swirl chamber and the second swirl chamber each have a nozzle for injecting fuel. Only the chamber is provided with a relief hole at a position opposite to its nozzle, and has a needle that throttles the fuel return passage from the relief hole in the middle and opens and closes the throttle in accordance with the pressure of the first swirl chamber, and A fuel injection valve having a swirl chamber and a check valve that is biased to close the relief hole by a weak spring between the needle and the relief hole and is opened by the fuel pressure in the first swirl chamber.