JPH0583805B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fuel injection valve, in particular a fuel injection valve with a swirl chamber suitable for gas turbine engines.

Prior Art In gas turbine engines, fuel injection valves equipped with a swirl chamber are often used. This type of fuel injection valve has excellent atomization performance, but its usable flow rate range is narrow. That is, the injection flow rate Q is proportional to the square root of the pressure difference Δp before and after. Therefore, in order to widen the flow range, the pressure difference Δp must be increased. This means that the pressure on the inlet side must be varied over a wide range, from high pressure at high flow rates to low pressure at low flow rates. However, when the pressure on the inlet side is lowered, the speed of the swirling flow in the vortex chamber, that is, the strength of the vortex, decreases.
This increases the thickness of the liquid film from the nozzle and increases the particle size of the spray. As a result, the atomized state becomes poor and it does not function satisfactorily at low flow rates. if,
If the required flow rate range of the fuel injection valve is narrow, it would be possible to make the pressure difference Δp sufficiently large by reducing the size of the inlet to the swirl chamber, but this is subject to significant processing constraints. In any case, fuel injection valves with a swirl chamber are not suitable for low flow rates.

Purpose of the Invention The present invention has been made in view of the above-mentioned drawbacks of the prior art, and it is possible to achieve sufficiently good atomization characteristics even in a low flow rate range, and to easily maintain the required flow rate even in a high flow rate range. you can get
As a result, it is an object of the present invention to provide a fuel injection valve with a swirl chamber that can be adapted to a wide range of required flow rates.

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. A fuel return passage is opened only in the first swirl chamber at a position opposite to its nozzle, and a fuel control mechanism having a flow rate control throttle is installed in the fuel return passage.

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 the second 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. In the present invention, two large and small swirl chambers are provided, and when the flow rate is small, the smaller swirl chamber takes charge of the injection, and when the flow rate is large, this swirl chamber and the larger swirl chamber take charge of the injection, respectively. . 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 attached to the O-ring 22.
are inserted into the nozzle body 12 via the outer cylinder 24, and are mutually fastened by the outer cylinder 24. The flange 241 of the outer cylinder 24 serves as a mounting portion to the wall surface of the combustion chamber.

As shown in an enlarged view in FIG. 4, 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. 2, 34 is a fuel supply connector 36
and a fuel return connector 38, which is fixed to the main body 10 by a cap 40 via an O-ring 41. 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 disposed within the cylindrical portion 401.
will be installed. 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 keeps the valve 42 open and the valve seat 4 at all times.
It is exerting an urging force that closes down 4. The valve hole of the valve seat 44 is the vertical hole 4 in the cap 40.
02, fuel supply connector 3 via horizontal hole 403
It communicates with the fuel hole 361 of No. 6. Backflow prevention valve 4
The combustion chamber 50 formed downstream of 2 includes 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, and an annular passage 54 in the valve body 18. the annular passage 5 between the valve body 18 and the vortex plate 16;
6 and the first swirl chamber 2 via the first inlet 58
6 (see Figure 4).

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. 4).

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. The swirl chamber 26 of the inlet 58 or 70 in such a tangential direction
or 28 by opening into the swirl chamber 26 or 28
It is well known that a swirling flow occurs within the air.

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 in the wall surface on the opposite side from the jet port 30. opening 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. Swirl chamber 26 includes opening 185 and restrictor member 74 , hole 207 in valve plate 20 , annular passage 76 between body 10 and valve plate 20 , body 10
Through the passages 105 and 106 inside, and the vertical holes 381 and horizontal holes 382 inside the fuel return connector 38,
It is connected to the pipe 7 in FIG. opening 18
5. Orifice 741 of throttle member 74, hole 20
7, annular passage 76, passages 105, 106, hole 38
1,382, pipe 7 constitutes the fuel return passage of the present invention. As shown in FIG. 2, the restricting member 74 is formed into a cup shape and is screwed into the bore 187 of the main body 18 and fixed therein. Throttle member 74 has an orifice 741 on its lower end surface, which sets the amount of fuel to be returned from swirl chamber 26 . The communication hole 185 that opens into the first swirl chamber 26 is equipped with a second check valve 80, which is normally operated by a spring 82 and an adapter 84 to prevent the valve seat 188 adjacent to the communication hole 185 from being closed. It exerts a blocking force.

To describe the operation of the device of the present invention described above, fuel from the flow control device 5 is introduced into the fuel supply connector 36 of the fuel injection valve 1 through the pipe 6, and
61, push open the check valve 42 through the holes 403 and 402, and enter the fuel chamber 50. From chamber 50, fuel enters passages 102, 52, 54, 56 and is introduced tangentially through first inlet 58 into first swirl chamber 26, creating a swirling flow therein. The swirling fuel flow flows from the first nozzle 30 to the second nozzle 32.
The liquid is then sprayed into the combustion chamber in the form of a thin conical liquid film F (Fig. 7). When the conical liquid film formed thinly in this way reaches a certain flight distance, it becomes finely atomized as shown in G. 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 represented by the solid line _l1 in FIG. In this pressure state, the fuel pressure acting on the control valve 60 is small, so the control valve 60 is closed and no fuel is supplied to the second swirl chamber 28.

When the fuel pressure reaches the set value _p1 , the fuel pressure acting on the control valve 60 overcomes the spring 62, and the valve 60 moves away from the valve seat 202, and the fuel flows 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, a swirling flow of fuel is generated in the second vortex chamber 28, and the fuel is sprayed from the injection port 32 into the combustion chamber. In this case as well, the spray is formed as a thin conical liquid film stream as explained in FIG. In this manner, at high pressure, the spray from the second swirl chamber 28 is generated in addition to the spray from the first swirl chamber 26, and the flow rate characteristics are as shown in FIG. A curve such as l ₂ is obtained by superimposing the flow rate characteristic from the second swirl chamber 28 on the flow rate characteristic.

The fuel pressure supplied in the first swirl chamber 26 acts on the ball 80 and forces it against the spring 82 into the valve seat 188.
Displace it more. That is, the first swirl chamber 26 includes the communication passage 185, the orifice 741, the passages 207, 1
05, 106, and communicates with the return pipe 7 through 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, even in a region where the injection amount is small, sufficient swirling flow intensity can be achieved in the swirl chamber 26, and sufficient atomization can be achieved even in this region. Conventionally,
Such a return piping system is not installed, and the spray amount characteristics from the first swirl chamber 26 at this time are shown in Fig. 6.
m ₁ street. For the same spray volume, for example g ₁ , according to the invention the pressure at the inlet of the swirl chamber is pl, whereas conventionally it is pm. As a result, the flow velocity within the vortex chamber 26 was lower than in the present invention, and this resulted in worsening of atomization.

The check valves 42 and 60 are returned to the closed position by the springs 48 and 82, respectively, after the fuel supply is stopped. This prevents fuel from flowing backwards and dripping from the nozzle during shutdown. Spring 4
8 and 82 are set to have an appropriately weak force so as to exhibit such a backflow prevention function, but not to impede the smooth flow of fuel during operation.

In the embodiment of FIG. 2 shown in FIGS. 8 and 9, the structure of the fuel injection valve 1 is the same as that in FIGS. 2 and 3. In addition, a second flow control device 80 is installed in the pipe 7', which corresponds to the return pipe 7 in FIG.
The flow rate control device 80 is configured as a valve device that makes the return flow rate in the pipe 7' zero or decreases in a large flow rate region. By setting up such a flow rate control device, as shown by the broken line in Fig. 6, the characteristic l 2 ' in the large flow rate region is equal to that of the conventional device without restriction (m ₂ ), and the characteristic l ₂ ' in the small flow rate region is In the region l ₁ ', the characteristics can be made equivalent to the characteristics (l ₁ ) of the present invention in which a diaphragm is installed. The pressure of the pump 4 shown in FIG. 1 can be lowered by not providing relief in the high flow rate range, and the pump power can be reduced.

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. 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 required flow rate can be obtained without increasing the output so much, and the diameter of the inflow hole to the swirl chamber can be increased, which facilitates processing.

[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 of FIG. 1, FIG. 3 is a top view of FIG. 2, and FIG. 1st
Figure 5 is a plan view of the swirl chamber, Figure 6 is a partially enlarged view of the figure.
The figure is a flow rate characteristic diagram of the fuel injector of the present invention, Figure 7 is an explanatory diagram showing the state of spray from the nozzle, Figure 8,
FIG. 9 is a diagram similar to FIGS. 2 and 3 showing a second embodiment of the present invention, and FIG. 10 is a diagram similar to FIG. 2 or 8 showing a third embodiment. 1, 1'...Fuel injection valve, 7...Return pipe,
26, 28... vortex chamber, 30, 32... nozzle, 7
4... Throttle member, 741... Orifice.

Claims (1)

[Claims] 1. A first vortex chamber with a small volume connected to a fuel supply pump and a second vortex chamber with a large volume, and between the second vortex chamber and the fuel supply pump, a fuel A control valve is provided that opens when the 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. A fuel injection valve in which a fuel return passage is opened only in the first swirl chamber at a position opposite to its nozzle, and a fuel control mechanism having a flow rate control throttle is installed in the fuel return passage. 2. The fuel injection valve according to claim 1, wherein the flow rate control mechanism includes a throttle having a fixed size and a check valve that suppresses or eliminates the return flow rate passing through the fixed throttle.