GB2543767A

GB2543767A - Valve

Info

Publication number: GB2543767A
Application number: GB1518926.9A
Authority: GB
Inventors: Hussain Zahid
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2015-10-27
Filing date: 2015-10-27
Publication date: 2017-05-03
Also published as: GB201518926D0

Abstract

A butterfly valve comprises a housing 34 defining a fluid flow path and a valve member 32 pivotable relative to the housing for variably controlling fluid flow along the fluid flow path. An abradable layer 40 of epoxy resin is provided on an inner surface of the housing 34 in a region of the valve member 32. The valve member 32 can thus be made with a larger diameter since removal of the abradable layer 40 ensures that the required clearance between the valve member 32 and the housing 34 is provided.

Description

Valve

Technical Field

The present disclosure concerns a butterfly valve, a gas turbine engine, a method of manufacturing a valve and/or gas turbine engine, and/or a method of repairing a butterfly valve, for example a butterfly valve of a gas turbine engine.

Background

Gas turbine engines are typically employed to power aircraft. Typically a gas turbine engine will comprise an axial fan driven by an engine core. The engine core is generally made up of one or more turbines which drive respective compressors via coaxial shafts. The fan is usually driven off an additional lower pressure turbine in the engine core.

The fan comprises an array of radially extending fan blades mounted on a rotor and air travelling through the fan will provide a large percentage of the overall thrust generated by the gas turbine engine. The remaining portion of air from the fan is ingested by the engine core and is further compressed, combusted, accelerated and exhausted through a nozzle. The engine core exhaust mixes with the remaining portion of relatively high-volume, low-velocity air bypassing the engine core.

It is known to extract air from the working gas path of a gas turbine engine, either to manage the engine airflow and operating conditions or to provide an air supply for the passenger cabin or for other purposes. Generally, this air is extracted through one or more bleed valves in an engine casing, which are actuated (for example, by a solenoid or hydraulic actuator) to either an open position in which air can flow through it or a closed position in which no air can flow through it.

Air may be bled from the compressor to manage the operating conditions of the engine and/or for auxiliary functions such as providing air to a cabin of an aircraft. A valve is usually provided to control the bleed from the compressor.

Conventionally the valve is a binary valve, that is the valve is of the type where it is either open or closed.

In industries other than the gas turbine industry, variable valves such as butterfly valves are known. A butterfly valve has a valve member that is provided in a valve housing and is pivotable thereto so as to open or close and vary the flow of fluid through the butterfly valve. So as to reduce leakage through the seal, it is common practice to provide an elastomeric seal around the edge of the valve member. This elastomeric seal needs to be regularly replaced, and to do this it is necessary to disassemble the butterfly valve.

Summary of Disclosure

According to a first aspect there is provided a butterfly valve comprising a housing defining a fluid flow path and a valve member pivotable relative to the housing for variably controlling fluid flow along the fluid flow path. An abradable layer is provided on an inner surface of the housing in a region of the valve member.

The valve member may be pivotable between a closed position where fluid is substantially blocked from flowing along the fluid flow path, and an open position where a maximum cross sectional area of the fluid flow path is exposed to fluid flow therealong. The valve member may be pivotable to one or more positions between the closed position and the open position. For example, the valve member may be arranged such that fluid flow along the fluid flow path can be continually variable.

The abradable layer may be provided in a region of the housing opposite a circumferential face of the valve member when the valve member is in the closed position.

The housing may comprise a recess and the abradable layer may be provided in the recess.

The recess may have a maximum depth at a position opposite a circumferential face of the valve member when the valve member is in a closed position.

The recess may be shaped so as to have a gradual transition from a minimum depth to a maximum depth.

The abradable layer may be only provided in the recess.

The valve member may be pivotably connected to the housing. For example, the valve member may be pivotably connected to the housing at two opposing points. The axis extending between the two opposing points may define an axis of rotation.

The valve member may be disc shaped. The valve member may have one or more planar faces.

The butterfly valve may comprise an actuator configured to pivot the valve member. For example, to pivot the valve member between the open and closed position and/or any position therebetween.

The abradable layer may be made from an epoxy resin.

The valve may comprise an actuator configured to pivotally move the valve member relative to the housing.

According to a second aspect there is provided gas turbine engine comprising a bleed duct for receiving bleed flow (e.g. bleed flow from a compressor of the gas turbine engine) and a valve member pivotable relative to the bleed duct for variably controlling fluid flow along the bleed duct. An abradable layer is provided on an inner surface of the bleed duct in a region of the valve member.

The gas turbine engine may comprise the valve according to the first aspect.

The housing may define a portion of the bleed duct.

In such an embodiment, the valve member of the second aspect is the same valve member as the valve member of the first aspect, and the abradable layer of the second aspect is the same abradable layer as the first aspect.

The bleed duct may have a larger diameter downstream of the valve than upstream of the valve.

The gas turbine engine may comprise a bypass duct and a compressor. The bleed duct may extend to bleed air from the compressor to the bypass duct. A pair of bleed ducts and corresponding valve members may be provided at a plurality of circumferentially spaced locations. A single actuator may be provided to actuate both valve members of the pair. In exemplary embodiments, a single actuator may be provided to operate the valve members provided in two or more pairs of bleed ducts.

According to a third aspect there is provided a method of manufacturing a butterfly valve. The method comprises providing a housing that defines a fluid flow path, providing a layer of abradable on an inner surface of the housing, and pivotally mounting a valve member to the housing (e.g. after the abradable layer has been provided on an inner surface of the housing).

The method may comprise providing a recess (e.g. machining a recess) in the inner surface of the housing, and providing abradable material in the recess to form the abradable layer.

The valve member may be mounted to the housing. The method may comprise removing the abradable material from the butterfly valve, whilst the valve member is mounted to the housing. The method may further comprise providing a new layer of abradable material, whilst the valve member is mounted to the housing.

The skilled person will appreciate that except where mutually exclusive, a feature described in relation to any one of the above aspects may be applied mutatis mutandis to any other aspect.

Description of the drawings

Embodiments will now be described by way of example only, with reference to the Figures, in which:

Figure 1 is a sectional side view of a gas turbine engine;

Figure 2 is a sectional schematic of a bleed arrangement between a bypass duct and compressor of the engine of Figure 1;

Figure 3A is a view of a valve assembly of the bleed arrangement of Figure 2 in a closed position when viewed from an axial end of the valve assembly;

Figure 3B is a view of a valve assembly of the bleed arrangement of Figure 2 in an open position when viewed from an axial end of the valve assembly;

Figure 4A is a sectional side view of the valve assembly of Figure 3A and 3B in the closed position;

Figure 4B is a sectional front view of the housing of the valve assembly of Figure 4A; and

Figure 4C is a perspective view of a section of the housing of Figure 4B. Detailed Description

With reference to Figure 1, a gas turbine engine is generally indicated at 10, having a principal and rotational axis 11. The engine 10 comprises, in axial flow series, an air intake 12, a propulsive fan 13, an intermediate pressure compressor 14, a high-pressure compressor 15, combustion equipment 16, a high-pressure turbine 17, and intermediate pressure turbine 18, a low-pressure turbine 19 and an exhaust nozzle 20. A nacelle 21 generally surrounds the engine 10 and defines both the intake 12 and the exhaust nozzle 20.

The gas turbine engine 10 works in the conventional manner so that air entering the intake 12 is accelerated by the fan 13 to produce two air flows: a first air flow into the intermediate pressure compressor 14 and a second air flow which passes through a bypass duct 22 to provide propulsive thrust. The intermediate pressure compressor 14 compresses the air flow directed into it before delivering that air to the high pressure compressor 15 where further compression takes place.

The compressed air exhausted from the high-pressure compressor 15 is directed into the combustion equipment 16 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive the high, intermediate and low-pressure turbines 17, 18, 19 before being exhausted through the nozzle 20 to provide additional propulsive thrust. The high 17, intermediate 18 and low 19 pressure turbines drive respectively the high pressure compressor 15, intermediate pressure compressor 14 and fan 13, each by suitable interconnecting shaft.

Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. By way of example such engines may have an alternative number of interconnecting shafts (e.g. two) and/or an alternative number of compressors and/or turbines. Further the engine may comprise a gearbox provided in the drive train from a turbine to a compressor and/or fan.

Referring now to Figure 2, a bleed arrangement from the compressor, in this case the intermediate pressure compressor 14 is indicated generally at 24. The bleed arrangement includes a bleed duct 26 for receiving a bleed flow from the compressor. A flexible seal 28 is provided and circumferentially surrounds a portion of the bleed duct. The flexible seal is provided to prevent leakage of bypass air into a fire zone that is located around the bleed duct, and to prevent leakage of fire zone ventilation air into the bypass duct 22. A valve assembly 30 is provided between an engine casing 29 proximal to the compressor and the bypass duct 22.

The cross sectional area of the bleed duct 26 is greater downstream of the valve assembly 30 than upstream of the valve assembly (upstream and downstream referring to the general direction of air flow through the bleed duct). The walls of the bleed duct are substantially parallel, but in alternative embodiments the walls may converge towards the bypass duct 22. In the present embodiment the bleed duct is open directly to the bypass duct 22, however in alternative embodiments a barrier may be provided between the bypass duct 22 and the bleed duct 26. The barrier may be a perforated sheet or a wire mesh. The perforations in the sheet or the holes formed in the mesh may be small enough to prevent debris such as bolts entering the bleed duct. In some embodiments the barrier may be a “pepperpot”. In such embodiments, the perforations or holes may be small enough to reduce noise (for example they may have a diameter of approximately 3mm).

Referring now to Figures 2 to 4C, the valve assembly 30 will be described in more detail. The valve assembly 30 is a butterfly valve. The valve assembly includes a valve member 32 and a housing 34. The housing 34 defines a fluid flow path for fluid flow through the valve assembly, and defines a portion of the bleed duct 26. In the present example the housing is cylindrical.

The valve member 32 is disc shaped. In the present example the faces of the valve member are planar, but in alternative embodiments the faces of the valve member may have any suitable profile.

The valve member 32 is pivotally connected to the housing 34. The valve member is connected to the housing at two diametrically opposed positions. The valve member 32 is connected to the housing 34 such that the valve member is pivotable about a rotational axis 36. The rotational axis 36 extends between the two positions of connection with the housing.

An actuator 38 is provided. The actuator 38 is configured to move the valve member 32 between an open and a closed position. In the present example the actuator is a ram, e.g. a hydraulic or pneumatic ram. In example embodiments multiple bleed ducts and valve assemblies may be provided. Multiple actuators may be provided to move the valve members between the open and closed positions. In some embodiments, a single actuator may be operable to move two or more valve members.

The closed position of the valve member 32 is illustrated in Figure 3A. In the closed position the valve member substantially blocks the fluid flow path defined by the housing 34. It could be considered that in the closed position, when the valve assembly 30 is viewed from an axial end, the valve member is concentric the fluid flow path (or bore) of the housing. The open position of the valve member 32 is illustrated in Figure 3B. In the open position the valve member is positioned so as to block the fluid flow path by a minimal amount. In the present example, the valve member 32 is positioned orthogonal to the closed position. When the valve assembly is viewed from an axial end, in the open position only a portion of the circumferential face of the valve member is visible.

Referring now in particular to Figures 4A, 4B and 4C, an abradable layer 40 is provided on an inner surface of the housing 34. The abradable layer can be considered to define a portion of the fluid flow path through the housing. The abradable layer 40 is provided in a region of the valve member 32. That is, the abradable layer is directly opposite the circumferential face of the valve member when the valve member is in the closed position. In the present example, the abradable layer extends axially forward and axially rearward of the valve member. A recess 42 is provided in the housing 34. The recess extends circumferentially around the housing. In the present example, the recess extends around the full circumference of the housing. The abradable layer 40 is provided in the recess 42. The abradable layer is only provided in the recess. The recess is positioned directly opposite the circumferential face of the valve member when the valve member is in the closed position, and the recess extends axially forward and axially rearward of the valve member (when the valve member is in the closed position).

The recess 42 has a curved profile. The depth of the recess is greatest (in an axial direction) at a position opposite the circumferential face of the valve member when the valve member is in the closed position. In the present example the depth of the recess continuously increases to be greater at a position furthest from a position where the valve member is connected to the housing. However, in alternative embodiments the depth of the recess may be constant in a circumferential direction (but may still vary in an axial direction). In further alternative embodiments the recess may be a channel of substantially constant depth in an axial direction. In a yet further alternative embodiment the sides of the channel may be planar or angled instead of being curved.

The recess is completely filled with abradable layer, and as such, before any wear has occurred, the thickness of the abradable varies similarly to the depth of the recess.

To manufacture the valve assembly 30, the recess 42 is machined into the bore (or inner surface) of the housing 34. Abradable material is then provided in the recess. In the present embodiment, the abradable material is an epoxy resin.

Provision of the recess and abradable material means that the valve member 32 can be made to a larger relative diameter than comparable valve members in the related art, which means that the clearance between the housing 34 and the valve member 32 can be significantly reduced so as to reduce leakage. Conventionally the gap between the valve member and the housing may be expected to be between 0.25 and 0.5 mm. In the present embodiment, the gap can be reduced to less than or equal to 0.3 mm.

During use of the gas turbine engine 10 and/or valve assembly 30, the actuator 38 is used to control a flow of bleed air along the bleed duct 26 from the compressor by moving the valve member 32 between the open and closed positions and various positions therebetween. Using a butterfly valve in the bleed arrangement means that the bleed flow can be continuously varied, rather than only having an open or closed configuration (and none in between), as with bleed arrangements of gas turbine engines of the prior art.

As the valve member 32 moves between the open and closed position, the circumferential face of the valve member may rub against the abradable layer and abrade a portion of the abradable layer. In this way the valve member can be made with a larger diameter than would otherwise be possible because removal of the abradable layer ensures the required clearance is provided between the valve member and the housing.

Provision of an abradable layer instead of an elastomeric seal that is provided with butterfly valves of the related art means that the seal can be capable of operating in higher pressure and/or higher temperature environments.

Furthermore, in butterfly valve assemblies of the related art, when an elastomeric seal is provided around the valve member, the valve assembly needs to be disassembled to replace the elastomeric seal which will typically wear at a greater rate than the remainder of the valve assembly. However, in the described example of a butterfly assembly, the filler material can be removed and replaced without the need to disassemble the valve assembly.

It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and subcombinations of one or more features described herein.

Claims

1. A butterfly valve comprising: a housing defining a fluid flow path; a valve member pivotable relative to the housing for variably controlling fluid flow along the fluid flow path; and an abradable layer provided on an inner surface of the housing in a region of the valve member.

2. The butterfly valve according to claim 1, wherein the housing comprises a recess and the abradable layer is provided in the recess.

3. The butterfly valve according to claim 2, wherein the recess has a maximum depth at a position opposite a circumferential face of the valve member when the valve member is in a closed position.

4. The butterfly valve according to claim 3, wherein the recess is shaped so as to have a gradual transition from a minimum depth to a maximum depth.

5. The butterfly valve according to any one of claims 2 to 4, wherein the abradable layer is only in the recess.

6. The butterfly valve according to any one of the previous claims, wherein the abradable layer is made from an epoxy resin.

7. The butterfly valve according to any one of the previous claims comprising an actuator configured to pivotally move the valve member relative to the housing.

8. A gas turbine engine comprising: a bleed duct for receiving bleed flow (e.g. bleed flow from a compressor of the gas turbine engine); a valve member pivotable relative to the bleed duct for variably controlling fluid flow along the bleed duct; and an abradable layer provided on an inner surface of the bleed duct in a region of the valve member.

9. The gas turbine engine according to claim 8 comprising the valve according to any one of claims 1 to 7, wherein the housing defines a portion of the bleed duct.

10. The gas turbine engine according to claim 8 or 9, wherein the bleed duct has a larger diameter downstream of the valve than upstream of the valve.

11. The gas turbine engine according to any one of claim 8 to 10, wherein the gas turbine engine comprises a bypass duct and a compressor, and wherein the bleed duct extends to bleed air from the compressor to the bypass duct.

12. The gas turbine engine according to any one of claims 8 to 11, wherein a pair of bleed ducts and corresponding valve members is provided at a plurality of circumferentially spaced locations.

13. A method of manufacturing a butterfly valve, the method comprising: providing a housing that defines a fluid flow path; providing a layer of abradable on an inner surface of the housing; and pivotally mounting a valve member to the housing.

14. The method according to claim 13, comprising providing a recess (e.g. machining a recess) in the inner surface of the housing, and providing abradable material in the recess to form the abradable layer.

15. A method of repairing a butterfly valve according to any one of claims 1 to 7 where the valve member is mounted to the housing, the method comprising: removing the abradable material from the butterfly valve, whilst the valve member is mounted to the housing; and providing a new layer of abradable material, whilst the valve member is mounted to the housing.

16. A valve, gas turbine engine and/or method substantially as hereinbefore described with reference to and/or as shown in the accompanying drawings.