WO1994015084A1

WO1994015084A1 - Flow distributor valve

Info

Publication number: WO1994015084A1
Application number: PCT/GB1993/002653
Authority: WO
Inventors: Geoffrey Charles Todd
Original assignee: Lucas Industries Plc
Priority date: 1992-12-23
Filing date: 1993-12-23
Publication date: 1994-07-07
Also published as: GB9226886D0

Abstract

A fluid flow distribution valve (2) has a fluid flow input (3), two fluid flow outputs (4, 6), a valve member (9) movable between an initial and a main flow position and which controls two main flow paths between the input (3) and each of the two outputs (4, 6) by blocking said main flow paths when in the initial position, and by splitting the flow from the input in a predetermined ratio between the two outputs when in the main flow position. A flow restrictor (21) is connected in an initial flow path between the input (3) and an initial flow output (4). The initial flow path includes the valve member (9) so that it passes an initial flow from the input (3) to the initial flow output (4) when the valve member (9) is in the initial flow position, and blocks said initial flow path when the valve member (9) is in the main flow position. The valve member (9) is subject to the pressure differential across the flow restrictor (21) so that it moves from the initial to the main flow position when the rate of flow through the restrictor (21) exceeds a predetermined level corresponding to a maximum initial flow rate. Preferably, the flow outputs (4', 6') are subdivided into a plurality of outputs (4', 6') each controlled individually by the valve member (9) to produce an output flow.

Description

FLOW DISTRIBUTOR VALVE

Technical Field

This invention relates to a fluid flow distribution valve, especially one adapted to control an input fluid flow so as to pass this flow to one output or set of outputs at flow rates up to a predetermined maximum flow rate, and to split this flow in predetermined proportions between two outputs or sets of outputs at flow rates above said predetermined maximum flow rate. In a typical application, a valve of this type is used to control the supply of fuel to the injectors of an aero engine so that some only are supplied with fuel at a low flow rate during engine start-up conditions before the fuel is supplied to all of the injectors at a higher fuel flow rate for normal running conditions.

Disclosure of Invention

According to the present invention, a fluid flow distribution valve has a fluid flow input, two fluid flow outputs, a valve member movable between an initial flow position and a main flow position and which controls two main fluid flow paths between the input and each of the two fluid flow outputs by blocking said main fluid flow paths when in the initial position and by splitting the fluid flow from the input in a predetermined ratio between the two outputs when in the main flow position, and a fluid flow restrictor connected in an initial fluid flow path between the input and an initial flow output, the initial

1 fluid flow path including the valve member so that it passes an initial fluid flow from the input to the initial flow output when the valve member is in the initial flow position and blocks said initial fluid flow path when the valve member is in the main flow position, the valve member being subject to the pressure differential across the fluid flow restrictor so that it moves from the initial flow position to the main flow position when the rate of fluid flow through the restrictor exceeds a predetermined level corresponding to a maximum initial flow rate.

Preferably, the initial flow output is one of the two outputs, particularly that one of the two outputs which passes the lesser fluid flow.

Preferably, the valve member comprises a spring-loaded spool valve with opposite sides connected to the input and initial flow output downstream of the valve member. Further, a fluid flow restrictor is preferably provided between the valve member and the initial flow output.

Preferably, the valve member communicates with the two main fluid flow paths via shaped ports which open progressively more rapidly as the valve member moves from the initial flow position to the main flow position.

Each of the fluid flow outputs may be subdivided into a plurality of outputs, each controlled individually by the valve member to produce an output flow. Also, additional flow restrictors may be provided downstream of the first mentioned flow restrictor so as to control the initial flow of fuel to the initial outputs.

Description of the Drawings

The invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a schematic section through a fluid flow distribution valve according to the invention;

Figure 2 is a section on the line 2-2 in Figure 1;

Figure 3 is a plan view of one of the shaped ports in the spool valve shuttle of Figure 1;

Figure 4 is a schematic diagram of an aero engine fuel distribution system including the distribution valve of Figures 1 to 3;

Figure 5 is a schematic section through an alternative embodiment of the invention;

Figure 6 is a schematic diagram of an aero engine fuel distribution system including the distribution valve of Figure 5; and Figure 7 is a schematic section through another alternative embodiment of the invention.

Mode of Carrying out the Invention

The aero engine fuel distribution system illustrated in Figure 4 comprises a fuel control unit 1 which delivers fuel at a required flow rate to the input 3 of a flow distribution valve 2. Under engine start-up conditions, the control unit 1 delivers fuel at a low flow rate, and whilst this flow rate remains below a predetermined maximum initial flow rate, the fuel is delivered by the distribution valve 2 via an output 4 and manifold 5 to a set of seven fuel injectors 28. Thus, although the fuel flow rate is low, the full supply to these seven fuel injectors is sufficient to ensure efficient combustion.

As the control unit 1 increases the fuel flow rate above said predetermined maximum initial flow rate, the distribution valve

2 operates to split the flow in a predetermined ratio between the output 4 and a second output 6. The output 6 is connected via a manifold 7 to a set of seventeen fuel injectors 28, and the ratio of the fuel supplied to the manifolds 5 and 7 is 7:17 so as to ensure that fuel is delivered at the same rate to all of the injectors of both manifolds.

The flow distribution valve 2 is illustrated in Figures 1 to

3 and comprises a valve body 8 in which is slidably mounted a spool valve 9. The spool valve has an elongate tubular portion 10 closed at one end 27, and a piston head 11 formed at its other end. The tubular portion 10 slides in a bore 12, and the piston head 11 slides in bore 13 which contains a helical coil spring 14 that surrounds the tubular portion 10 and acts between the valve body 8 at one end of the bore 13 and the underside of the piston head 11.

The input 3 of the flow distribution valve 2 is connected to the bore 13 on the topside of the piston head 11, and thence via a central aperture 15 in the piston head to the inside of the tubular portion 10 of the spool valve. One ring of ports 16 is formed in the tubular portion 10 at an intermediate point in its length and cooperates with an annular gallery 17 formed in the bore 12 that communicates with the second output 6 of the flow distribution valve 2. A second ring of ports 18 is formed in the tubular portion 10 near its closed end 27 and cooperates with the adjacent end of the bore 13 where it opens out into a chamber 19 connected to the output 4 of the flow distribution valve 2.

The chamber 19 is connected to the input 3 via a passage 20 which includes a flow restrictor 21 and a filter 22. The passage 20 opens into the chamber 19 at a port 23 at the end of the bore 12 so that the end of the tubular portion 10 cooperates with the port 23.

A passage 24 connects the chamber 19 to the bore 13 on the underside of the piston head 11 via a flow restrictor 25. In operation, when the fuel control unit 1 delivers no fuel to the input 3 of the flow distribution valve 2, the spool valve 9 is urged by the spring 14 against a stop 26. When the fuel control unit 1 delivers fuel to the input 3 at a flow rate below said predetermined initial flow rate, fuel flows through the filter 22, flow restrictor 21, port 23, and chamber 19 to the output 4. This is the initial fluid flow path which delivers an initial fluid flow via the output 4 to the manifold 5 and the seven injectors connected to it.

The pressure drop caused by the flow restrictor 21 creates a pressure differential across the spool valve 9 acting on both sides of the closed end 27 and both sides of the piston head 11. Up to the predetermined maximum initial flow rate, this pressure differential is insufficient to move the spool valve 9 against the action of the spring 14. However, at the predetermined maximum initial flow rate, the pressure differential is just sufficient to move the spool valve 9 against the action of the spring 14, and this causes the closed end of the tubular portion 10 to move across the port 23 as it extends into the chamber 19. As the port 23 is closed, the pressure in the chamber 19 falls, increasing the pressure differential across the spool valve 9, and thereby urging it to move more rapidly to fully close the port 23.

The movement of the piston head 11 and closed end 27 displaces fuel into the chamber 19 to maintain fuel flow to outlet 4 and manifold 5 at the same level as at the input 3.

Following closure of the port 23, continued movement of the spool valve 9 serves to open the two rings of ports 16,18 simultaneously as they move into overlapping relationship with the gallery 17 and the end of bore 12, respectively. Once these ports 16,18 open, fuel flows through each to their respective outputs 6,4 and thence on to the injectors connected to the manifolds 7,5.

The extent of opening of the ports 16,18 is determined by the flow rate delivered by the fuel control unit 1, the spool valve 9 moving to increase the opening to accommodate higher flow rates.

The relative proportions in which fuel is delivered to the two outputs 4,6 is determined by the relative areas of the ports 18,16, and is fixed for all positions of the spool valve once the ports 18,16 are opened.

As shown in Figure 3, the ports 16,18 are substantially triangular in shape so that they open from the point of the triangle, and thus produce a progressively increasing rate of opening with a constant rate of movement of the spool valve 9.

An alternative embodiment of the invention is illustrated in Figures 5 and 6 in which the flow distribution valve 2 is further adapted to supply fuel separately to individual portions of the manifolds feeding the injectors 28. The same reference numerals are used for similar components in Figures 1 and 5, and Figures 4 and 6. As shown in Figure 6, the manifold supplying the injectors 28 used for engine start-up is sub-divided into three shorter manifolds 5' each connected to three injectors 28. The manifold supplying the other injectors 28 is sub-divided into five shorter manifolds 7' each connected to three injectors.

The distribution valve 2 has a spool valve 9 with a ring of ports 16 which each cooperate with a respective one of five outputs 6' each connected to one of the manifolds 5'.

The distribution valve 2 also has a second ring of ports 18 which control the flow of fuel to the remaining injectors 28 connected to the manifolds 7'. However, the tubular portion 10 of the spool valve 9 is extended beyond these ports 18 and includes additional flow control ports that further control the flow to the manifolds 7' as follows.

A ring of small diameter ports 29 in the tubular portion 10 cooperate with an annular galley 30 in the bore 12 so that they communicate with the gallery when the spool valve 9 is in the initial flow position, shown in Figure 5, and are closed when the spool valve moves to the main flow position. An insert 31 within the tubular portion 10 against the end wall 27 incorporates a filter 22 and a flow restrictor 21 which lie in an initial fluid flow path from the input 3, through the valve member 9, and out through the ring of ports 29 into the gallery 30.

The gallery 30 is connected via a passage 33 to a further gallery 34 surrounding the tubular portion 10' that extends beyond the end wall 27. A ring of ports 35 in the extended tubular portion 10' are in constant communication with the gallery 34 and conduct fuel on through the initial fluid flow path.

Two further rings of ports 36,37 in the extended tubular portion 10' finally control communication of the interior of the extended tubular portion 10' with a set of three outputs 4' which are each connected to one of the manifolds 5' . The ring of ports 36 consists of ports of short axial length and high circumferential width which each communicate with one of the outputs 4' when the spool valve is in the initial flow position, as shown in Figure 1. An insert 38 within the extended tubular portion 10' includes a filter 39 and individual flow restrictors 40, which each lie in the initial fluid flow path to one of the outputs 4' .

Thus, when the spool valve 9 is in the initial flow position, fuel flows from the input 3, through the tubular portions 10, 10' and both inserts 31,38 to the outputs 4'. The pressure drop across the flow restrictor 21 in insert 31 serves to control the position of the spool valve by virtue of the connection 24 from the gallery 30 through the damping restrictor 25 to the underside of the pistol head 11. The pressure drop across the individual flow restrictors 40 in insert 38 serve to ensure an even flow distribution between the three outputs 4' .

The ring of ports 37, like the ring of ports 16 and 18, are closed when the spool valve 9 is in the initial flow position. However, these ports all open together when the spool valve moves to its main flow position, a respective one of each of the ports 37 then communicating with one of the three outputs ' . Fuel then flows from the input 3 through the tubular portion 10 and ports 16 to the outputs 6', and on through the ports 18, gallery 30, passage 33, gallery 34, ports 35, and ports 37 to the outputs 4'. The input flow of fuel is split between the outputs 4',6' according to the relative effective areas of the ports 16, and of the ports 18 and 37 combined through which the output flows pass.

An alternative embodiment of the invention is illustrated in Figure 7, which like the embodiment of Figures 5 and 6, is adapted to supply fuel separately to individual portions 5' ,7' of the manifolds shown in Figure 6. The same reference numerals are used for equivalent components in Figures 5 and 7.

The distributor valve 2 has a coaxial fuel input 3 at one end which supplies fuel through a sieve 22 to the central aperture 15 of the tubular portion 10 of the spool valve 9. The input 3 communicates with the top of the piston head 11 of the spool valve. A first ring of ports 16 each cooperate with a respective one of five outputs 6' (only one shown in Figure 7) each connected to one of the manifolds 7'. A second ring of ports 18 cooperate with ports 41 in a fixed sleeve 42 around the tubular portion 10 of the spool valve so as to control the flow of fuel into an outer gallery 30.

A cup-shaped member 43 is connected to the end of the tubular portion 10 where it projects from the sleeve 42, and this has an annular wall 44 which surrounds the end of the tubular portion 10 and defines part of the outer gallery 30. The annular wall 44 cooperates with an outer fixed sleeve 45 within the valve body 8, and the wall 44 is formed with a ring of ports 37 which each cooperate with a respective port 46 in the sleeve 45 which is connected to a respective output 4' and manifold 5' .

When the spool valve is in the initial flow condition, shown in Figure 7, both rings of ports 16 and 18 are closed. However, a galley 47 in the tubular portion 10, which is connected to the central aperture 15 through port 48, is aligned with a ring of flow restrictors 29 in the outer fixed sleeve 42; and a ring of restrictors 36 in the annular wall 44 are each aligned with a respective port 46 in the outer sleeve 45. Thus, there is an initial fluid flow path through the input 3, port 48, gallery 47, restrictors 29, gallery 30, restrictors 36 and ports 46 to respective outputs 4' and manifolds 5'. The pressure drop across the restrictors 29 serves to control the position of the spool valve by virtue of the connection 24 from the outer galley 30 to the underside of the piston head 11.

As the fuel pressure at the input 3 increases, the spool valve 9 moves to the right, to the main flow position, in which the ports 16 and 18 in the spool valve are aligned with respective outputs 6' and ports 41 in the outer sleeve 42, and the ports 37 in the annular wall 44 are aligned with respective outputs 4' , thereby allowing fuel to flow to the outputs 4' ,6' and respective manifolds 5' ,7' .

Claims

1. A fluid flow distribution valve has a fluid flow input, two fluid flow outputs, a valve member movable between an initial flow position and a main flow position and which controls two main fluid flow paths between the input and each of the two fluid flow outputs by blocking said main fluid flow paths when in the initial position and by splitting the fluid flow from the input in a predetermined ratio between the two outputs when in the main flow position, characterised in that a fluid flow restrictor (21) is connected in an initial fluid flow path between the input (3) and an initial flow output (4), the initial fluid flow path includes the valve member (9) so that it passes an initial fluid flow from the input (3) to the initial flow output (4) when the valve member (9) is in the initial flow position and blocks said initial fluid flow path when the valve member (9) is in the main flow position, and the valve member (9) is subject to the pressure differential across the fluid flow restrictor (21) so that it moves from the initial flow position to the main flow position when the rate of fluid flow through the restrictor (21) exceeds a predetermined level corresponding to a maximum initial flow rate.

2. A fluid flow distribution valve as claimed in claim 1 further characterised in that the initial flow output (4) is that one of the two outputs which passes the lesser fluid flow.

3. A fluid flow distribution valve as claimed in claim 1 or 2 further characterised in that the valve member (9) comprises a spring-loaded spool valve with opposite sides connected to the input (3) and initial flow output (4) downstream of the valve member (9) .

4. A fluid flow distribution valve as claimed in claim 3 further characterised in that a fluid flow restrictor (25) is provided in a connection (24) between the valve member (9) and the initial flow output (4).

5. A fluid flow distribution valve as claimed in any one of the preceding claims further characterised in that the valve member (9) communicates with the two main fluid flow paths (4,6) via shaped ports (18,16) which open progressively more rapidly as the valve member (9) moves from the initial flow position to the main flow position.

6. A fluid flow distribution valve as claimed in any one of the preceding claims further characterised in that either or both of the fluid flow outputs (4',6') is subdivided into a plurality of outputs (4'6'), each controlled individually by the valve member (9) to produce an output flow.

7. A fluid flow distribution valve as claimed in claim 6 further characterised in that the initial flow output (4') is sub-divided into a plurality of outputs, and an additional flow restrictor (39) is provided for each initial flow output (4') downstream of the first mentioned flow restrictor (21) so as to control the initial flow of fuel to the initial outputs (4').

8. A fluid flow distribution valve as claimed in claim 6 or 7 further characterised in that the valve member (9) has a valve portion (10' or 35) with individual ports (37) to control the main fluid flow to each of the initial flow outputs (4').

9. A fluid flow distribution valve as claimed in claim 8 further characterised in that said valve portion comprises an annular member (35) which surrounds one end of the valve member (9).

10. A fluid flow distribution valve as claimed in any one of the preceding claims further characterised in that the valve member (9) is movably axially of itself between the initial flow and main flow positions and said fluid flow input (3) is located at one axial end of the valve member (9) remote from the initial flow output.

11. A fluid flow distribution valve as claimed in claim 10 in which the valve member (9) has an axial aperture (15) through which fluid flows to the fluid flow outputs (4,6).

12. A fuel supply system for an aero engine including a fluid flow distribution valve as claimed in any one of the preceding claims.

13. A fluid flow distribution valve substantially as herein described with reference to Figures 1 to 4, or Figures 5 and 6, or Figure 7 of the accompanying drawings.