Fluid flow device

Abstract

An apparatus (2) for controlling the flow of fluid through a conduit (1) from an upstream side (6) of the apparatus (2) to a downstream side (8) of the apparatus (2). The apparatus (2) includes a valve seat (26) mounted on a housing (10) defining a valve bore (20), a mounting member (14) disposed on the downstream side (8) of the valve bore (20), a valve member (16) mounted on the mounting member (14). The valve member (16) is arranged to selectively open and close the valve bore (20) to control the flow of fluid through the valve bore (20). A seal retaining member (28) is disposed adjacent the valve seat (26) and defines a seal retaining groove (26a) with the valve seat (26). A flexible seal (30) within the seal retaining groove (26a) seals the valve bore (20) when the valve member (16) is moved to close the valve bore (20).

Description

[0001] The present invention relates to a device for controlling the flow of fluid therethrough, in particular to a device comprising a valve member for opening and closing a valve bore to control the flow of fluid through the device.

[0002] In fluid flow systems such as pipes and conduits, for example, in many different industrial situations, it is necessary to regulate the pressure in the fluid flow. In such systems, the input pressure can be constant or fluctuate over time, and it can be desirable to maintain or control to a lower target output pressure, which can also be constant or fluctuating.

[0003] The pressure in such systems can be regulated using a pressure regulator. The flow through the pressure regulator is selectively controlled by a valve member which opens and closes one or more valve bores, for example depending on one or more of the pressure in the downstream side of the conduit, the pressure in the upstream side of the conduit and a control pressure which it is arranged to act on the valve member.

[0004] In such pressure regulators, when the valve bore is fully closed by the valve member, i.e. in the "closed" position, a seal between the valve member and the housing of the pressure regulator helps to minimise leakage of fluid through the valve bore.

[0005] It is an object of the present invention to provide a device for controlling the flow of fluid through a conduit having an improved seal arrangement.

[0006] Viewed from a first aspect, the present invention provides a device for controlling the flow of fluid through a conduit from an upstream side of the device to a downstream side of the device, the device comprising:

[0007] a housing;

[0008] a valve seat mounted on the housing, the valve seat defining a valve bore;

[0009] a mounting member arranged on the downstream side of the valve bore;

[0010] a valve member movably mounted on the mounting member, wherein the valve member is arranged to reciprocate to selectively open and close the valve bore to control the flow of fluid through the valve bore;

[0011] a seal-retaining member arranged adjacent the valve seat such that the seal-retaining member and the valve seat together define a seal-retaining groove; and

[0012] a flexible seal arranged within the seal-retaining groove for substantially sealing the valve bore when the valve member is moved to close the valve bore.

[0013] The present invention provides a device for controlling (e.g. pressure regulating) fluid flow through a conduit (e.g. a conduit in which the device is placed). Fluid flow through the device is controlled between an upstream side and a downstream side of the device, for example, a valve bore of the device defines a boundary between the upstream side and the downstream side. Fluid passes through the valve bore, and thus through the device, from the upstream side to the downstream side, controlled by a valve member that is movably mounted on a mounting member. The mounting member is arranged in the device downstream of the valve bore (and thus preferably the valve member is arranged downstream of the valve bore) and the valve member is arranged to reciprocate on the mounting member to selectively open and close the valve bore, and thus fluid flow through the valve bore can be controlled.

[0014] A valve seat mounted on the housing of the valve (e.g. around other components of the device) defines the valve bore of the device. The valve seat and the seal-retaining member together define a seal-retaining slot in which a flexible (e.g. deformable) seal is located. The valve seat and the seal-retaining member serve to retain the flexible seal within the slot. When the valve member moves to close the valve bore, the flexible seal is arranged and acts to substantially seal the valve bore, for example, by the valve member contacting the flexible seal on the valve seat.

[0015] To retain the seal within the slot, fine tolerances can be required. The valve seat and the seal-retaining member can be separate from the housing, and thus can (and in embodiments are) machined separately. The valve seat and the seal-retaining member can be significantly smaller than the housing. This facilitates machining of the slot for the seal to fine tolerances. If the slot were defined by the housing (which is typically much larger than the valve seat and retaining member), then machining the housing to define the slot to the required tolerances can be both expensive and complex. In embodiments of the invention, the housing can be manufactured to looser tolerances than the valve seat and the seal-retaining member.

[0016] Eliminating the requirement for the housing to maintain fine tolerances can allow the housing to be manufactured from a cheaper (and thus, potentially, less corrosion resistant) material (e.g. ductile cast iron) and to be coated to prevent corrosion. This is a variable process in which it can be more difficult to maintain fine tolerances. The housing can be manufactured from uncoated stainless steel.

[0017] The fluid flow control device of the present invention can be any suitable and desired such device configured to control the flow of fluid through it. The device can comprise a pressure reducing valve. Thus, the device can be arranged to control the flow of fluid through a valve bore to cause a pressure drop in the fluid, for example, from an upstream side to a downstream side of the device. The device can comprise a pressure maintaining valve. Thus, the device can be arranged to maintain a constant pressure upstream of the device. The fluid can be water.

[0018] The housing can be provided in any suitable and desired manner, e.g. with a valve seat mounted thereon to define a valve bore. In some embodiments, the housing comprises a wall on which the valve seat is mounted. The housing (e.g. the wall of the housing) can be attached to (and sealed against) the mounting member (e.g. on the downstream side of the mounting member). Attaching the housing (and thus the valve bore) e.g. structurally and directly to the mounting member facilitates precise alignment of the valve member within the device and thus relative to the valve bore.

[0019] The housing can comprise a pipe section. The housing can be arranged to fit within a conduit, e.g. between an upstream portion of the conduit and a downstream portion of the conduit. The device can comprise a flange (e.g. arranged on (e.g. welded to) an outer surface of the housing) for connection to an upstream or downstream side of the conduit. The flange can be arranged at a downstream and / or upstream end of the housing. Thus, the device can comprise two flanges (two ends) for connection to the conduit. The upstream and / or downstream flange enables the device to be connected (e.g. bolted) to one or more corresponding flanges on the upstream and / or downstream portions of the conduit.

[0020] In some embodiments, the mounting member is mounted (e.g. directly) to the housing. In some embodiments, the mounting member is mounted (e.g. to the housing) to (e.g. a downstream) flange. Such an arrangement can help to simplify manufacture and construction of the device. In some embodiments, the mounting member and (e.g. downstream) flange are integral with one another. In some embodiments, the mounting member and flange are distinct parts.

[0021] The mounting member can be attached to (e.g. a downstream) flange. The mounting member can be fixedly mounted (e.g. bolted) to (e.g. in a recess of) the (e.g. downstream) flange. Thus, the device can be manufactured with a “split core”, allowing the mounting member, flange and housing to be manufactured from a smaller volume of initial material. This can be less expensive than manufacturing the core of the device from a single piece of material, which requires a larger starting volume and more complex manufacturing processes to achieve the required geometry.

[0022] In some embodiments, the device (e.g. the housing of the device) has a diameter of between 5 cm and 190 cm. Thus, the device can be suitable for connection within a conduit having a diameter of between 5 cm and 190 cm. The device can be configured to operate with water as the working fluid.

[0023] The valve bore can be arranged relative to the mounting member and valve member and conduit in any suitable and desired configuration. In some embodiments, the valve bore lies in a plane perpendicular to the axis of the mounting member, and thus in some embodiments also perpendicular to the axis of the device. The valve bore can be any suitable or desired shape. In some embodiments, the valve bore is circular.

[0024] The housing can define an internal volume substantially surrounding the mounting member and the valve member, e.g. the mounting member and the valve member are arranged in the internal volume of the housing.

[0025] The valve member is movably mounted on the mounting member such that it can move reciprocally on the mounting member and thus reciprocally relative to the valve bore. In some embodiments, the mounting member is cylindrical. In some embodiments, the valve member moves along an axis parallel to the (e.g. cylindrical) mounting member, and e.g. parallel to the axis of the device and / or the direction of the conduit, e.g. coaxially around the mounting member.

[0026] The device can comprise one or more bearing strips arranged between the mounting member and the valve member. The bearing strips can help to reduce friction opposing movement of the valve member. In some embodiments, the bearing strips are made of PTFE. In some embodiments, the bearing strips are mounted on the valve member. In some embodiments, the bearing strips are mounted on the mounting member.

[0027] The device and its components can be arranged in any suitable and desired manner. In some embodiments, the mounting member, the valve member and the valve bore (and also preferably the device itself, and e.g. the housing, the valve seat and the seal retaining member) are arranged coaxially with each other around an axis. The mounting member, the valve member and the valve bore (and also preferably the device itself, and e.g. the housing, the valve seat and the seal retaining member) can be substantially rotationally symmetrical around the axis. In some embodiments, the axis extends in a direction that is co-linear with the general (average) direction of fluid flow through the valve bore.

[0028] The axis of the device can be parallel to, e.g. co-linear with, the axis of the conduit in which the device is arranged. It will be appreciated that such an arrangement allows the device to be easily installed within an existing conduit. Thus, no additional space can be required to accommodate the device, and it can be quickly and cost-effectively re-installed in most parts of a pipework or most pipe joints without any major modification of the pipework. Thus, the device according to the present application can significantly reduce the cost and effort required to incorporate said device into an existing system.

[0029] In some embodiments, the valve member is mounted on the outside of the mounting member. In some embodiments, a bearing strip is provided between the valve member and the mounting member. This helps to reduce friction between components that would otherwise impede movement of the valve member. In some embodiments, the bearing strip is provided on the valve member. In some embodiments, the bearing strip is provided on the mounting member.

[0030] The valve member and the mounting member can define a control volume therebetween. Thus, the fluid flow control device can comprise a control volume defined between the mounting member and the valve member. The control volume can contain a control pressure arranged to bias the valve member towards the valve bore. The device can comprise an arrangement for introducing the control pressure into the control volume.

[0031] Thus, the valve member can move towards the valve seat to close the valve bore when the upstream pressure is low (e.g. lower than the control pressure), and can move away from the valve seat to open the valve bore when the upstream pressure is high (e.g. higher than the control pressure). Thus, the valve member can be acted upon by the pressure on the upstream side and the control pressure, and thereby move by the difference between these pressures.

[0032] In some embodiments, the device comprises a spring arranged within the control volume to bias the valve member towards the valve bore.

[0033] The device can comprise a valve seal arranged between the mounting member and the valve member. Thus, the valve seal can be arranged to prevent leakage of fluid from an internal volume of the device (e.g. fluid flowing through the device) into the control volume, and vice versa. The valve seal can be manufactured from PTFE. The valve seal can be arranged between the two bearing strips. The valve seal can be mounted on the valve member. In some embodiments, the valve seal is mounted on the mounting member.

[0034] A (e.g. central) protrusion of the distal end (e.g. upstream) of the valve member can have a width (e.g. diameter) that is less than a width (e.g. diameter) of the valve bore. This allows the (e.g. central) protrusion on the distal end (e.g. upstream) of the valve member to move within the valve bore when the valve member is moved to close the valve bore. The (e.g. circumference) of the distal end (e.g. upstream) of the valve member can be arranged to abut the valve seat when the valve member is moved to close the valve bore.

[0035] In some embodiments, the valve seat extends radially inwards (e.g. into the internal volume of the device) from the housing. The valve seat can extend (e.g. completely) around the housing (e.g. inner circumference (e.g. circumference)). In some embodiments, the valve seat has a substantially annular shape, e.g. defining the valve bore therein. The valve seat can be mounted (e.g. welded) directly to the housing.

[0036] The housing can comprise a mounting flange (e.g. protruding rim) extending radially inwards (e.g. into the internal volume of the device). The mounting flange can extend (e.g. completely) around the housing (e.g. inner circumference (e.g. circumference)). In some embodiments, the mounting flange comprises an annular space, e.g. defining a central bore. The mounting flange can be an integral part of the housing. In some embodiments, the mounting flange can be separate from the housing. It can be fixed (e.g. welded, bolted) to the housing (inner surface).

[0037] In some embodiments, the valve seat is mounted on the mounting flange (e.g., a (e.g., upstream) surface of the mounting flange). The valve seat can include a portion that projects radially inward (e.g., into the internal volume of the device) rather than the mounting flange. This portion of the valve seat can thus define the valve bore.

[0038] The valve seat can provide a stop for the valve member when the valve member is moved to close the valve bore. The valve seat can include a (e.g., downstream) valve-facing surface. The valve-facing surface can be arranged to abut a corresponding (e.g., upstream) surface of the valve member (e.g., radially outward of a central protrusion on a distal end of the valve member) when the valve member is moved to close the valve bore. In some embodiments, the (e.g., downstream) valve-facing surface can be defined by a portion of the valve seat that projects radially inward (e.g., into the internal volume of the device) more than the mounting flange.

[0039] The valve seat can be sealed relative to the housing, e.g., by a seal between the valve seat and the housing. In some embodiments, the valve seat is sealed on the mounting flange of the housing.

[0040] The seal-retaining member can be any suitable or desired shape. In some embodiments, the seal-retaining member is substantially circular. The seal-retaining member can be generally annular, e.g., defining a central bore. The seal-retaining member can be substantially rotationally symmetric about an axis of the overall (average) direction of fluid flow through the device (e.g., the valve bore of the device).

[0041] In some embodiments, the valve seat at least partially defines a slot for receiving the seal-retaining member. The slot can be at least partially defined by the housing (e.g., the mounting flange), e.g., together with the valve seat. For example, when the valve seat is mounted on the housing (e.g., the mounting flange), the valve seat and the housing (e.g., the mounting flange) can together define (e.g., between them) the slot for receiving the seal-retaining member.

[0042] In some embodiments, the shape of the slot is complementary to the shape of the seal-retaining member. The slot can be adjacent to a (e.g., downstream) valve-facing surface of the valve seat that is arranged to abut a corresponding (e.g., upstream) surface of the valve member when the valve member is moved to close the valve bore. The slot can extend (e.g., azimuthally, e.g., completely) around (e.g., its (e.g., outer) circumference) the valve seat (e.g., the valve-facing surface).

[0043] The seal-retaining member can be arranged (e.g., within the slot) such that it projects from the (e.g., downstream) surface of the valve seat relative to at least a portion of the (e.g., downstream) surface of the valve seat adjacent to it (e.g., radially inward of the seal-retaining member). The seal-retaining member can thus define a (e.g., radially outer) edge of the seal-retaining slot.

[0044] The valve seat can comprise a lip arranged on a (e.g. downstream) valve-facing surface of the valve seat. The lip can be substantially circular. The lip can extend (e.g. azimuthally, e.g. completely) around the valve seat (e.g. (e.g. inner) circumference). The lip can be arranged radially inwards of the seal-retaining member (e.g. the slot for accommodating the seal). The lip can define an (e.g. inner) edge of the seal-retaining slot. Thus, the seal-retaining member (e.g. arranged within the slot) and the lip of the valve seat can define the seal-retaining slot therebetween.

[0045] In some embodiments, the valve seat is mounted to (e.g. mounting flange) the housing (e.g. overlapping it) such that the housing (e.g. mounting flange) protrudes radially inwards of a radially outwards portion of the slot for accommodating the seal-retaining member. This means that a portion of the housing (e.g. the mounting flange of the housing) partially overlaps with the slot, thereby further defining the slot. The overlapping portion of the housing can define a bulbous portion of the slot (e.g. having a dimension (e.g. cross-sectional area) that is larger than a corresponding dimension of the (e.g. downstream) opening of the slot).

[0046] The shape of the seal-retaining member is preferably substantially complementary to the shape of the slot. Thus, the seal-retaining member can comprise a (e.g. complementary) bulbous portion (e.g. a (e.g. upstream) end (bulb portion) of the seal-retaining member that can have a dimension (e.g. cross-sectional area) that is larger than a corresponding dimension of an intermediate (e.g. central) portion of the seal-retaining member arranged in the bulbous portion of the slot). The bulbous portion of the seal-retaining member can be located within the bulbous portion of the slot such that the seal-retaining member is effectively retained within the slot.

[0047] The width (e.g. diameter) of the distal end (e.g. upstream) of the valve member can be such that the valve member (e.g. outer perimeter of the distal end) partially overlaps a radially inwards portion of the downstream surface of the seal-retaining member when the valve member is moved to close the valve bore. Thus, for example, the valve member (e.g. outer perimeter of the distal end) can fully overlap the flexible seal when the valve member is moved to close the valve bore.

[0048] The housing (e.g. inner perimeter) (e.g. mounting flange of the housing) can be radially outwards of the valve member (e.g. outer perimeter of the distal end (e.g. upstream) end) such that a gap is defined between the valve member and the housing (e.g. mounting flange) in the valve bore when the valve member is moved to close. This gap can be in fluid communication with the fluid downstream of the valve bore.

[0049] In some embodiments, the valve member (and e.g. seal-retaining member, valve seat and / or housing) are arranged such that when the valve member is moved to close the valve bore, a radially inwards portion of the downstream surface of the seal-retaining member is in contact with the valve member and an outer portion of the downstream surface of the seal-retaining member is exposed to the fluid downstream of the valve bore.

[0050] In some embodiments, the seal-retaining member is (for example slightly) smaller than the slot in which it is arranged. Thus, in some embodiments, a leakage path is defined between the seal-retaining member and the housing (for example, the mounting flange), and between the seal-retaining member and the valve seat. Preferably, the leakage path extends around the perimeter of the seal-retaining member, such that fluid downstream of the valve bore and the back surface of the flexible seal are in fluid communication. The back surface of the seal can be substantially opposite the contact surface of the seal. The contact surface of the seal can be arranged to contact the valve member when the valve member is moved to close the valve bore. As noted above, providing a gap between the outer perimeter of the valve member and the housing can improve such fluid communication between the downstream fluid and the back surface of the seal.

[0051] The presence of such a leakage path means that low pressure from downstream of the valve bore can be fed to the back surface of the flexible seal, thereby reducing the pressure differential acting on the seal for pulling the seal out of the groove. By reducing this pressure differential, the seal is less likely to be pulled out of the groove. The seal-retaining member is provided as a separate part from the valve seat and the housing, allowing such a leakage path to be defined without the need for additional complex manufacturing operations to be performed on the housing. This reduces the complexity of manufacturing the device.

[0052] The flexible seal can protrude from the seal-retaining groove, such that the valve member first contacts the flexible seal when the valve member is moved to close the valve bore, for example before the valve member contacts the valve seat.

[0053] The flexible seal can be substantially circular, for example annular. The seal can extend (for example azimuthally, for example entirely) around the seal-retaining groove and thus around the valve bore. The seal can be any suitable and desirable type of seal. Thus, the seal can be made of any suitable and desirable (for example deformable) material. The Young’s modulus of the sealing material can be less than the Young’s modulus of the material of the valve member (and / or other components). Thus, the seal can substantially deform before the valve member (and / or other components). In one embodiment, the flexible seal comprises an elastomer, for example a nitrile seal. In one embodiment, the seal comprises polytetrafluoroethylene (PTFE), polyurethane, ethylene propylene diene rubber (EPDM) rubber, or FKM (a.k.a. fluoroelastomer). Such materials can help allow the valve member to form an effective seal between the upstream side and the downstream side of the valve bore.

[0054] The seal can be located in a wake region of the flow through the device. This is due to separation from the surface upstream of this region, and so the flow velocity is significantly lower than the velocity of the fluid flowing through the centre of the valve bore. This can be on the downstream surface of the valve seat. Arranging the seal in the wake region means that particles that can come into contact with the seal that are suspended in the fluid have less kinetic energy, and so are less likely to damage the seal. Damage to the seal can result in the valve member being unable to form an effective (e.g. complete) seal when required (e.g. when closed). Therefore, reducing the risk of such damage can improve the functioning of the device and reduce the frequency at which the sealing device needs to be maintained, which can extend the service life of the device.

[0055] The valve seat (e.g. lip) and seal retaining member can be shaped such that the seal retaining groove is substantially triangular (e.g. in cross-section). In some embodiments, the seal retaining groove is a dovetail groove. The dovetail groove can be a standard (e.g. approximately 66°) dovetail O-ring groove. The dovetail shape enables the seal to be more effectively retained within the groove. The cross-section of the flexible seal can be complementary to the cross-section of the seal retaining groove.

[0056] In order to manufacture the device such that the groove is able to closely accommodate the seal, thereby allowing the seal to be more easily retained within the groove, the components defining the groove can need to be machined to fine tolerances. If the groove is defined solely by the housing of the device, which can be relatively large, then the housing will need to be machined to such fine tolerances. This can result in significant manufacturing costs due to the size of the housing. The valve seat and / or seal retaining member can be much smaller (e.g. in terms of their envelope size) than the housing. This means that the valve seat and / or seal retaining member can be manufactured to finer tolerances than the housing, without incurring excessive manufacturing costs. Therefore, defining the seal retaining groove by smaller components (i.e. the valve seat and seal retaining member) allows the required tolerances to be achieved at lower cost.

[0057] A preferred embodiment of the present application will now be described, by way of example only, with reference to the accompanying drawings in which:

[0058] Figure 1 A cross-sectional view of a device according to one embodiment of the present application is shown in an open configuration;

[0059] Figure 2 A cross-sectional view of a device according to one embodiment of the present application is shown in a closed configuration; and Figure 1 A cross-sectional view of a device according to one embodiment of the present application is shown in an open configuration;

[0060] Figure 3 A cross-sectional view of a device according to one embodiment of the present application is shown in an open configuration; Figure 1 An enlarged cross-sectional view of the sealing arrangement of the device.

[0061] There are many different industrial situations in which it is necessary to control the flow rate of a fluid flow through a conduit. In such systems, there is a need for a device for controlling the output flow rate by opening and / or closing an outlet (e.g. valve) aperture. As will now be described, embodiments of the present invention provide a device which is capable of providing this control over fluid flow.

[0062] Figure 1 A cross-sectional view of a fluid flow control device 2 according to an embodiment of the present invention is shown. The device 2 comprises a housing 10 which is made of ductile cast iron and then coated to prevent corrosion. The housing 10 comprises flanges 4, 5 on the upstream and downstream sides of the device 2 respectively, for mounting the device 2 between the upstream 6 and downstream 8 sides of a conduit 1 (e.g. with corresponding flanges to mount the flanges 4, 5 of the housing 10). In Figure 1 In use, fluid flows from left to right from the upstream side 6 of the conduit 1, through the device 2 and into the downstream side 8 of the conduit 1.

[0063] The housing 10 defines a cylindrical internal volume 12 which is in fluid communication with the upstream 6 and downstream 8 sides of the conduit 1. The housing 10 comprises a mounting ring 18 which projects radially from the housing 10 into the internal volume 12.

[0064] The device 2 further comprises a cylindrical mounting member 14 and a valve member 16 mounted on the mounting member 14. The mounting member 14 and valve member 16 are located within the internal volume 12 of the housing 10. The mounting member 14 projects perpendicularly in an upstream direction from the downstream flange 5.

[0065] The valve member 16, which has a cylindrical shroud portion 16a and an end cap 16b, is mounted on the outside of the mounting member 14 so that it is able to move reciprocally along the outer surface of the cylindrical mounting member 14. The outer surface of the mounting member 14 comprises a bearing strip 40 which is used to improve the movement of the valve member 16 along the outer surface of the mounting member 14,

[0066] The mounting member 14 defines a central bore 32. A helical spring 34 is arranged within the central bore 32 between the downstream inner surface of the central bore 32 and the inner surface of the end cap 16b. The spring 34 is thus arranged to bias the valve member 16 in an upstream direction. The outer surface of the mounting member 14 defines a groove in which an O-ring 42 is located to provide a seal between the downstream side 8 of the conduit 1 and the central bore 32.

[0067] The device 2 further comprises a valve seat 26 and a seal retaining member 28, both located within the internal volume 12 of the housing 10 upstream of the cylindrical mounting member 14. The valve seat 26 is coaxially mounted (e.g. bolted) to the upstream face of the mounting ring 18 and defines the central valve bore 20. The downstream face of the valve seat 26 comprises a circumferential first slot 26a in which the seal retaining member 28 is mounted. The valve seat 26 further comprises a lip 26b protruding from the downstream face of the valve seat 26. The seal retaining member 28 and the lip 26b together define a second dovetail O-ring groove 27 facing downstream.

[0068] The valve seat 26 is arranged such that the valve bore 20 is aligned with the valve member 16. Thus, the valve member 16 can move between a position in which the outer face of the end cap 16b is sealed against the downstream face of the valve seat 26 to completely close the valve bore 20 and a position in which the inner face of the end cap 16b abuts the end of the mounting member 14 (although the spring force exerted by the spring 34 can be arranged to prevent this).

[0069] The flexible seal 30 is located within the second groove 27 and protrudes beyond the surface of the downstream face of the valve seat 26. Thus, when the valve member 16 approaches the downstream face of the valve seat 26, it first contacts the seal 30.

[0070] To reduce the risk of particles in the fluid damaging the seal 30, the seal 30 is arranged on the downstream facing surface of the valve seat 26. This ensures that, for most of the operating range of the device 2, the seal 30 is within a wake region in which the flow velocity is significantly lower than the velocity of the fluid through the valve bore 20. As a result, any suspended particles that come into contact with the seal 30 have less kinetic energy and are therefore less likely to damage the seal 30.

[0071] To retain the seal 30 sufficiently within the groove 27, the valve seat 26 and the seal retaining member 28 are manufactured to have fine tolerances. As the seal 30 is retained by these smaller components 26, 28 rather than by the larger housing 10, the housing 10 can be manufactured to have much lower tolerances.

[0072] This means that the housing 10 can be coated to prevent corrosion. Coating processes are often not viable when fine tolerances are required. The ability to coat the housing 10 allows the housing 10 to be manufactured from relatively cheap cast iron. This reduces the manufacturing costs associated with the housing 10 whilst enabling the groove 27 to be manufactured with the required tolerances.

[0073] In operation, the upstream pressure of the fluid flow flowing through conduit 1 acts on the upstream face of end cap 16b, thus exerting a force on valve member 16 in the downstream direction, against the bias of spring 34. In some embodiments, a control pressure can be supplied to central bore 32 by a control pressure supply (not shown) to increase the downstream force on valve member 16. If the force exerted by the upstream fluid pressure is greater than the opposing force of spring 34 (and in some embodiments, the control pressure), valve member 16 moves to its open configuration, as shown in Figure 1 .

[0074] If the upstream fluid pressure decreases such that the force exerted by the upstream fluid pressure on end cap 16b is lower than the opposing force of spring 34 (and in some embodiments, the control pressure), valve member 16 moves to its closed configuration, as shown in Figure 2 . In the closed configuration, end cap 16b of valve member 16 is sealed against valve seat 26 by seal 30.

[0075] Figure 3 An enlarged cross-sectional view showing seal 30, mounting ring 18, valve seat 26, and seal retention member 28 is shown.

[0076] Mounting ring 18 extends into the interior volume 12 of housing 10 to a point at a radial distance from the inner surface of housing 10. As will be seen in Figure 3 , first slot 26a is defined by valve seat 26 at a similar radial distance from the inner surface of housing 10, such that mounting ring 18 partially overlaps first slot 26a, forming step 18a, which further defines slot 26a. Figure 3 It is shown that the cross-section of seal retention member 28 includes a bulbous end, similar to a tab of a jigsaw puzzle, which is arranged to fit a complementary portion of first slot 26a, defined between valve seat 26 and mounting ring 18. The interlocking geometry of these components helps to secure seal retention member 26 within slot 26a.

[0077] The position of valve member 16 in the closed configuration is indicated by the dashed line in the close-up cross-section of Figure 3 . The outer diameter of the distal end of valve member 16 is smaller than the inner diameter of mounting ring 18, such that a gap 12a is defined between valve member 16 and mounting ring 18. Flexible seal 30 is arranged radially inward from this gap 12a, thus serving to ensure that there is no fluid communication between gap 12a and upstream side 6 of conduit 1.

[0078] The valve seat 26 and the seal-retaining member 28 are machined such that a fluid flow path 36 is defined within the first groove 26a around the circumference of the seal-retaining member 28. The fluid flow path 36 is in fluid communication with the gap 12a and thus establishes fluid communication between the low pressure fluid in the internal volume 12 downstream of the valve bore 20 and the seal groove 27. Introducing low pressure behind the seal 30 in the seal groove 27 reduces the pressure differential acting on the seal 30, thereby reducing the risk of the seal 30 being pulled out of the groove 27. As this flow path 36 is defined by the valve seat 26 and the seal-retaining member 28, there is no need to machine a separate flow path (e.g. in the housing) to introduce low pressure behind the seal 30.

[0079] Figure 3 The sealing arrangement shown in Figure 3 also includes an O-ring 38 arranged radially outside the seal-retaining member 18 to provide a seal between the valve seat 26 and the mounting ring 18. This ensures that when the valve member 16 is in the closed configuration, there is no leakage of fluid from the upstream side 6 of the conduit 1 to the downstream side 8 of the conduit 1 via the fluid flow path 36.

[0080] As can be seen from the above, in at least the preferred embodiments of the present application, the device includes a sealing arrangement which can be machined to the high tolerances required to effectively retain a flexible seal without the need for expensive and complex machining of the valve housing. This helps to reduce the costs associated with manufacturing the device as it allows the housing of the device to be manufactured from cheaper materials and with lower tolerances. Manufacturing the sealing arrangement from a number of smaller components also allows a flow path to be defined which introduces downstream pressure to the backside of the seal, thereby reducing the pressure differential on the seal and reducing the risk of the seal being pulled out of the sealing arrangement.

Claims

1. A fluid flow device for controlling the flow of fluid through a conduit from an upstream side of the fluid flow device to a downstream side of the fluid flow device, the fluid flow device comprising: shell; A valve seat, which is mounted on the housing, defines a valve orifice; Mounting components are arranged on the downstream side of the valve orifice; A valve component movably mounted on the mounting member, wherein the valve component is arranged to reciprocate to selectively open and close the valve orifice, thereby controlling the flow of fluid through the valve orifice; A seal retaining member is arranged near the valve seat such that the seal retaining member and the valve seat together define a seal retaining groove; as well as A flexible seal disposed within the seal retaining groove for substantially sealing the valve orifice when the valve member is moved to close the valve orifice; The valve seat and the housing together define a slot for receiving the seal retaining member, and the seal retaining member is smaller than the slot in which the seal retaining member is arranged, thereby defining leakage paths between the seal retaining member and the housing and between the seal retaining member and the valve seat.

2. The fluid flow device according to claim 1, wherein, The outer casing includes pipe sections.

3. The fluid flow device according to claim 1 or 2, wherein, The fluid flow device includes a flange disposed on the outer surface of the housing for connecting the upstream side of the conduit and / or a flange disposed on the outer surface of the housing for connecting the downstream side of the conduit.

4. The fluid flow device according to claim 3, wherein, The mounting member is attached to the flange on the downstream side.

5. The fluid flow device according to claim 1 or 2, wherein, The fluid flow device includes one or more bearing strips arranged between the mounting member and the valve member.

6. The fluid flow device according to claim 1 or 2, wherein, The housing includes a radially inwardly extending mounting flange, on which the valve seat is mounted.

7. The fluid flow device according to claim 1 or 2, wherein, The valve seat includes a valve-facing surface arranged to adjoin a corresponding surface of the valve member when the valve member moves to close the valve orifice.

8. The fluid flow device according to claim 1 or 2, wherein, The valve seat is mounted to the housing such that the housing protrudes radially inward from a radially outward portion of the slot to accommodate the seal retaining member to define a spherical portion of the slot, wherein the seal retaining member includes a spherical portion disposed within the spherical portion of the slot.

9. The fluid flow device according to claim 1 or 2, wherein, The seal retaining member is arranged such that at least a portion of its surface relative to the surface of the valve seat protrudes from the surface of the valve seat, thereby defining the edge of the seal retaining groove.

10. The fluid flow device according to claim 1 or 2, wherein, The valve seat includes a lip disposed on the valve-facing surface of the valve seat, thereby defining the edge of the seal retaining groove.

11. The fluid flow device according to claim 1 or 2, wherein, When the valve member is moved to close the valve orifice, the width of the distal end of the valve member has an outer perimeter that partially overlaps the radially inward portion of the downstream surface of the sealing member.

12. The fluid flow device according to claim 1 or 2, wherein, The housing is located radially outside the valve member, such that when the valve member is moved to close the valve orifice, a gap is defined between the valve member and the housing.

13. The fluid flow device according to claim 1 or 2, wherein, The valve member is arranged such that when the valve member is moved to close the valve orifice, the radially inward portion of the downstream surface of the sealing member contacts the valve member, and the exterior of the downstream surface of the sealing member is exposed to the fluid downstream of the valve orifice.

14. The fluid flow device according to claim 1 or 2, wherein, The seal is located in the wake region of the fluid flow through the fluid flow device.

15. The fluid flow device according to claim 1 or 2, wherein, The valve seat and the sealing member are shaped such that the cross-section of the sealing groove is approximately triangular or dovetail-shaped.

Images