JPH0583807B2 - - 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 first control valve is provided which opens when the fuel pressure is equal to or higher than a predetermined value and guides the fuel to the second swirl chamber, and the first swirl chamber and the second swirl chamber each control the injection of fuel. A fuel return passage is opened only in the first vortex chamber at a position opposite to the nozzle, and the opening area of the fuel return passage is controlled according to the fuel pressure in the first vortex chamber. A second control valve is provided.

Operation When the fuel pressure does not reach a predetermined value, the first control valve is closed, so fuel is supplied from the fuel supply pump only to the first vortex chamber, which has a small volume, and this first control valve is closed.
Fuel is injected from the first swirl chamber, and at this time, a portion 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 first 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 required 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 second control valve throttles its opening in accordance with the increase in pressure in the first swirl chamber to gradually reduce the amount of returned fuel.

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 rate 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 the return pipe.

FIG. 2 specifically shows the structure of the fuel injection valve 1 of the present invention. According to the present invention, the fuel injection valve 1 is provided with two large and small swirl chambers, and when the flow rate is small, the smaller swirl chamber injects, and when the flow rate is large, this swirl chamber and the larger swirl chamber inject the fuel. I'm trying to make them take charge. In the figure, 10 is a main body, and 12 is a nozzle holder. The nozzle holder 12 has a cylindrical shape, and a vortex holder 14, a vortex plate 16, a valve body 18, and a valve plate 20 are inserted in this order. In this inserted state, the main body 10 is inserted into the nozzle main body 12 via the O-ring 22, and the two are mutually fastened by the outer cylinder 24.

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 acts on the valve 42 to exert a biasing force that constantly closes the valve seat 44. 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 first control valve;
Constructed as a ball valve. The control valve 60 has a spring 62
Through the adapter 64, which receives this force, it receives a biasing force that causes it to sit on the valve seat 202 formed on the valve plate 20. Valve seat 2
The valve hole 02 opens into the annular passage 54 through a hole 204 in the valve seat 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. 7
0 into the second swirl chamber 28 (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 the opening of the inlet 58 into the swirl chamber 26 in such a tangential direction causes a swirling flow F within the swirl chamber 26 .

According to the present invention, the vortex chamber 26, which takes charge of injection when the flow rate is small, is provided with a relief opening 185 on the wall surface on the side opposite to the nozzle. An opening 185 is drilled in the vortex plate 16 to return some 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 includes an opening 185, a bore 187 in the valve body 18, a throttle member 74, a hole 207 in the valve plate 20,
The annular passage 76 between the body 10 and the valve plate 20, the passages 105, 106 in the body 10, and the vertical holes 381 and horizontal holes 3 in the fuel return connector 38.
It is connected to the pipe 7 in FIG. 1 via a pipe 82. Opening 185, bore 187, orifice 741 of the throttle member, hole 207, annular passage 76, passage 10
5, 106, holes 381, 382, and pipe 7 constitute the fuel return passage of the present invention. As shown in FIG. 3, the aperture member 74 has a cylindrical shape,
It is threaded into thread 187A in bore 187. The aperture member 74 has a hexagonal hole 740 at one end, and by inserting a tool into the hole and turning it, the amount of return described below can be adjusted. The throttle member 74 has an orifice 741 at the other end. A second control valve 75 is provided as a needle so as to face this orifice.
The needle 75 is connected to the orifice 74 by the spring 76.
It is under an urging force that blocks the The communication hole 185 that opens into the first swirl chamber 26 is provided with a second check valve 80 , which the lower end of the needle 75 abuts against, and which is moved by a spring 82 via an adapter 84 to a valve seat 188 . It exerts a biasing force that normally closes the communication hole 185.

To describe the operation of the device of the present invention described above, when the device is stopped, the first non-return valve 42 closes the valve seat 44 by the force of the spring 48, while the second non-return valve 42 closes the valve seat 44 by gravity. backflow prevention valve 80
A downward force is applied to close the opening 185. This prevents fuel from dripping out of the nozzle when stopped. It should be noted that during this stop, the upper end 761 of the spring 76 is configured to have some distance S from the throttle member 74 when the second check valve 80 is in the closed state. This appropriate
The axial position of the throttle member 74 is adjusted in advance so that the distance S is obtained.

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 (arrow F), creating a swirling flow therein. The swirling fuel flow is sprayed from the first nozzle 30 through the second nozzle 32 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 flying distance, it is finely atomized. When the pressure of the fuel from the flow rate control device 5 is low, the spray from the first swirl chamber 26 is
That is, it shares the responsibility of spraying in the low flow rate region, and its flow rate characteristics are expressed by the solid line _l1 in FIG. 6 with respect to the inlet pressure (that is, the fuel pressure from the flow rate control device) p. Note that in this pressure state, the first control valve 60
Since the fuel pressure acting on the vortex chamber 28 is small, it is closed and no fuel is supplied to the second vortex chamber 28.
In this low flow rate region, the pressure of the fuel supplied into the first vortex chamber 26 is increased by the pressure of the fuel supplied into the first vortex chamber 26 against gravity, since there is a gap S between the spring 76 and the throttle member 74. Push open the check valve 80 and eliminate the gap S. However, since the spring 76 is set to be stronger than the pressure in the swirl chamber 26 in this state, the needle 75 serving as the second control valve maintains the orifice 741 in the open state. That is, the first vortex chamber 26 includes the communication passage 185 and the orifice 7.
41, passage 207, 105, 106, hole 381,
It communicates with the return pipe 7 via 382. The return flow rate at this time is determined by the diameter of the orifice 741 and the distance between the needle valve and 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. If such a return piping system is not installed, the spray amount characteristics from the first swirl chamber 26 will be as _m1 . For the same amount of spray, the pressure at the inlet of the vortex chamber can be increased by installing a return pipe. 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 approaches the characteristic m ₁ when there is no orifice, as indicated by x in FIG. 5. At the time of pressure _p2 , the needle 75 completely closes the orifice 741, and as a result, the amount of returned fuel becomes zero and the injection amount characteristic becomes _m1 .

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. Indicated by the thin line in the diagram
l ₁ and l ₂ are the characteristics when the orifice 741 is a fixed throttle, and m ₁ and m ₂ are the characteristics when the orifice 741 is not 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.

FIGS. 6 and 7 show a modification, which is equipped with a control valve 90 that integrates a check valve part 80' and a needle part 75'. There is virtually no change in the effect.

In the present invention, as shown in the graph of FIG. 5, in the low flow rate range, the area 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 characteristics of l ₁ to the characteristics of m ₁ occurs smoothly between the pressures of p ₁ and p ₂ , and if the switching point
This suppresses the sudden change in flow rate that would occur if the switch was made at _p3 .

Effects of the Invention Two swirl chambers, a first swirl chamber and a second swirl chamber are provided, and a first control valve opens the supply of fuel to the second swirl chamber when the fuel pressure is higher than a predetermined value. The fuel is returned only from the first swirl chamber through the return passage. 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 a second control valve is provided to control the amount of return, it is possible to obtain a good fuel atomization state over a wide flow rate range, and to increase efficiency, it is possible to obtain a good fuel atomization state over a wide flow rate range. This has the effect of making it possible to smoothly transition between the low flow rate area where injection is performed and the high flow rate area where injection is also performed from the second vortex chamber.

[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 FIG. 5 is a flow rate characteristic diagram of the fuel injection valve of the present invention, and FIGS. 6 and 7 are a sectional view and a plan view showing a second embodiment of the present invention. 1...Fuel injection valve, 7...Return pipe, 26,
28... Vortex chamber, 30, 32... Nozzle, 74...
Aperture member, 741... Orifice, 75, 90...
...control 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 first control valve is provided that opens when the valve is opened to guide fuel to a second swirl chamber, and the first swirl chamber and the second swirl chamber each have a nozzle for injecting fuel. Only one swirl chamber has a fuel return passage opened at a position opposite to its nozzle, and is provided with a second control valve that controls the opening area of the fuel return passage according to the fuel pressure in the first swirl chamber. fuel injection valve.