This invention relates to a one-way valve in which a valve member moves within a chamber in a valve body between a closed position in which the valve member engages a seat in the valve body and an open position in which the valve member is displaced from the valve seat by fluid flowing through the valve in a normal direction from an inlet to an outlet. Fluid flow in the reverse direction is prevented when the valve member is in the closed position.

Forces applied to a valve member to cause it to move between its open and closed positions can cause damage to the surface of the valve member or to a valve seat or other surfaces of a chamber in a valve body in which it moves, as a result of impact with the valve seat and those surfaces. Such damage can reduce its ability to form a seal reliably to close the valve. This problem can be greater in small size valves and can require the use of larger valves than are needed to accommodate fluid flow rates in order to achieve adequate reliability.

CN-U-2314184 discloses a one-way valve having a cylindrical body which is mounted vertically in use with the flow inlet below the flow outlet. A ball valve member can move within a chamber within the body. The chamber has a valve seat at its lower end. A guiding cylinder which has a perforated wall is fastened to the upper end wall of the chamber and has a recess for the ball valve member at its lower end. The ball valve member is displaced from the valve seat when fluid flows through the valve and engages the recess on the end of the perforated guiding cylinder. Gravity causes the ball valve member to engage the valve seat in the absence of fluid flowing through the valve.

The invention provides a one-way valve in which a valve member translates in a chamber defined by a valve body, and the valve body defines a bypass channel through which fluid can flow separated from the chamber between a first channel port which is open to the chamber at a location adjacent to a seat for the valve member and spaced in a direction towards the flow outlet from the point of contact between the valve member and the valve seat, and a second channel port which is open to the chamber at a location spaced in a direction towards the flow outlet from the first channel port, and in which the valve member is a close sliding fit in the chamber throughout its translation between its open and closed positions so that fluid flow between the flow inlet and the flow outlet is primarily through the bypass channel.

The invention therefore provides a one-way valve comprising a valve body having a flow inlet and a flow outlet and a bore extending through the valve body between the flow inlet and the flow outlet, and a valve member, in which the bore defines a chamber in which the valve member can translate, the chamber having a valve seat, and in which the valve member can translate in the chamber between an open position in which the valve member is separated from the valve seat allowing flow through the chamber in a normal direction from the flow inlet to the flow outlet, and a closed position in which it engages the valve seat to close the chamber against flow of fluid in a reverse direction from the flow outlet towards the flow inlet, the valve body also defining a bypass channel through which fluid can flow, separated from the chamber, between a first channel port which is open to the chamber at a location adjacent to the valve seat and spaced in a direction towards the flow outlet from the point of contact between the valve member and the valve seat, and a second channel port which is open to the chamber at a location spaced in a direction towards the flow outlet from the valve member when it is in its open position, in which the valve member is a close sliding fit in the chamber throughout its translation between its open and closed positions so that fluid flow between the flow inlet and the flow outlet is primarily through the bypass channel.

The one-way valve provided by the invention has the advantage that the vulnerability of the valve member to damage as a result of its movement to its closed position in which it engages the valve seat is reduced compared with other valves in which the flow path for fluid to flow between the valve inlet and the valve outlet extends through the chamber in which the valve member moves. This advantage arises because of the separation of the flow of fluid through the bypass channel from the fluid which acts on the valve member to cause it to move between its open and closed positions. The force with which the valve member engages the valve seat can be less than in other valves. The possibility of oscillating movement of the valve member is reduced. The reduced susceptibility of the valve member to wear can mean that the size of a valve as provided by the invention which might be used in a particular application can be smaller compared with the size of alternative valves. This has advantages in terms of reductions in both size and weight.

Furthermore, the control over the movement of the valve member by the action on it of fluid flowing in the reverse direction means that the valve can operate reliably without the need for a spring to bias the valve member towards is closed position, which is a feature of many one-way valves. Elimination of the need for a return spring means that the valve of the invention is more reliable than valves in which a return spring is used because such springs can fail. It is a preferred feature of the valve of the invention that it does not include a spring acting on the valve member to bias the valve member towards its closed position.

Furthermore, the control over the movement of the valve member by the action on it of fluid flowing in the reverse direction means that the valve can operate reliably without necessarily having to be mounted in a particular orientation, for example vertically so that gravity acts on the valve member.

Advantages of the valve of the invention arise from the close sliding fit of the valve member in the chamber throughout its translation from its open position to its closed position. The close sliding fit is such that the valve member can move along the axis of the valve which is defined by the cylinder without impediment due to frictional forces arising from the closeness of the valve member to the internal wall of the chamber. The close sliding fit is such that the open area between the external surface of the valve member and the internal wall of the chamber is small, so that the flow of fluid between the valve member and the cylinder wall is minimal.

It will often be preferred for the walls of the chamber to be continuous so that they do not have apertures formed in them through which fluid can flow into or out of the chamber. This can help to ensure that fluid flow between the flow inlet and the flow outlet is primarily through the bypass channel and not through the chamber. Advantages of the valve of the invention also arise from the valve member being exposed on the surface which faces the valve outlet to the pressure of fluid in the outlet; it is exposure to this pressure which causes the valve member to move from its open position to its closed position.

Optionally, the cross-sectional area of the valve member measured on a plane which is perpendicular to the axis defined by the movement of the valve member between its open and closed positions is greater than the minimum cross-sectional area of the bypass channel. For example, the ratio of the cross-sectional area of the valve member measured on a plane which is perpendicular to the axis defined by the movement of the valve member between its open and closed positions to the minimum cross-sectional area of the bypass channel can be at least about 1.05, especially at least about 1.1, or at least about 1.15.

The bypass channel can be provided by two or more bores in the valve body. A plurality of bores can be provided which extend along the valve axis. For example, the bypass channel might be provided by at least four bores which extend in parallel along the valve body, especially at least six bores or at least eight bores. Multiple bores can terminate at one or each end at an annular groove which can in some devices connect the bores to one another. When the bypass channel is provided by multiple bores, the minimum cross- sectional area of the bypass channel is determined by identifying the minimum cross- sectional area along the length of the bypass channel, which might be provided by the bores, or by one or both of the annular grooves. An annular groove can provide a flow path between the chamber and the ends of multiple bores which make up the bypass channel.

Including annular grooves to link axially extending bores to the flow inlet and the flow outlet results in fluid flow along the bores including multiple changes of direction, each through an angle approaching 90°. This can sometimes help to reduce unwanted flow of fluid through the bypass channel in the reverse direction. Optionally, the ratio of the maximum cross-sectional area of the flow path for fluid flowing through the chamber when the valve member is in its open position to the minimum cross- sectional of the flow path for fluid flowing through the bypass channel is not more than about 0.3, optionally not more than about 0.2, especially not more than about 0.15. This means that most of the fluid which flows through the valve when the valve member is in its open position flows through the bypass channel.

The chamber for the valve member will generally have an approximately constant cross- section, at least over most of its length. Frequently the chamber will be circular when viewed in cross-section and will have an approximately constant diameter over most or all of its length towards the valve seat. The valve member can be spherical when the chamber is circular when viewed in cross-section.

Optionally, the chamber and the valve member are circular when viewed in cross-section along an axis defined by the movement of the valve member between its open and closed positions, and the ratio of the diameter of the valve member to the diameter of the chamber is at least about 0.7, optionally at least about 0.8, especially at least about 0.9. This means that most of the fluid which flows through the valve when the valve member is in its open position flows through the bypass channel. The amount of fluid which flows around the valve member through the chamber is restricted because of the small space between the wall of the chamber and the valve member.

Optionally, the ratio of the length of the flow path for fluid to flow along the bypass channel between the first and second channel ports to the distance measured along the axis on which the valve member moves between its open and closed positions is at least about 2, optionally at least about 3, especially at least about 4. Advantages of the one-way valve of the invention arise from quick movement of the valve member from the open position to the closed position, which can help to minimise flow of fluid through the flow inlet in the upstream direction prior to the valve member reaching its closed position.

Quick movement of the valve member to the closed position can also be assisted by fluid in the chamber on the upstream side of the valve member being at relatively low pressure, so that any fluid that is present there can be displaced quickly by the valve member as it moves towards its closed position.

Optionally, the chamber and the valve member are circular when viewed in cross-section along an axis defined by the movement of the valve member between its open and closed positions, and the ratio of the diameter of the chamber to the distance moved by the valve member between its open and closed positions is at least about 3, optionally at least about 4, especially at least about 5.

Optionally, the valve member is circular when viewed in cross-section along an axis defined by the movement of the valve member between its open and closed positions, and the ratio of the diameter of the valve member to the distance moved by the valve member between its open and closed positions is at least about 3, optionally at least about 4, especially at least about 5.

It can be preferred that the flow path which is defined by the bypass channel is tortuous. Optionally, the flow path for fluid to flow along the bypass channel between the second channel port and the first channel port includes at least two corners, each of which involves a change in the direction of flow of fluid through an angle of at least about 45°.

Optionally, the angle between the axis on which the valve member moves between its open and closed positions, and the direction of flow of fluid through the first channel port is from about 45° to about 135°. Directing reverse flow fluid which is flowing from the first channel port into the chamber towards the axis of the chamber can sometimes help to reduce the possibility of the reverse flow fluid from the bypass channel interfering with translation of the valve member towards its closed position.

Optionally, the angle between the axis on which the valve member moves between its open and closed positions, and the direction of flow of fluid through the second channel port is from about 45° to about 135°. Arranging for the direction of flow of fluid through one or each of the channel ports to be generally transverse (from about 45° to about 135°) to the axis of the chamber can sometimes help to reduce unwanted flow of fluid through the bypass channel in the reverse direction.

Optionally, the shape of the valve seat when the valve is viewed in cross-section is conical or generally conical, and may be generally frusto-conical. This has the advantage of enabling a reliable line seal to be formed between the valve seat and a valve member which is spherical.

Optionally, the first channel port is located in or closely adjacent to the end that is remote from the valve inlet of the surface which provides the valve seat. The first channel port can be located partially or wholly on the surface which provides the valve seat. This will be adjacent to the region of the valve seat surface which is engaged by the valve member when in its closed position, downstream in the normal flow direction. The first channel port can be located partially or wholly on the surface of the chamber which defines the constant cross-section cylindrical portion of the chamber. The first channel port can be provided partially on the surface which provides the valve seat and partially on the surface of the chamber which defines the constant cross-section cylindrical portion of the chamber.

The valve member can be spherical. This can facilitate formation of a seal with the valve seat to close the valve against flow of fluid through the valve in the upstream direction (that is, the direction from the flow outlet to the flow inlet), irrespective of the orientation of the valve member relative to the axis on which it moves between its open and closed positions.

The valve member can be made from a resiliently deformable material. This can be particularly appropriate when the valve seat is provided by a relatively hard material such as a metal. Examples of suitable deformable materials include rubbers, especially ethylene-propylene copolymer rubbers, polysiloxane rubbers and nitrile rubbers. The material for a valve member will be selected so that the valve member can withstand the conditions which it is exposed to when the valve is in use, including the operating temperatures and pressures of the valve, and materials which the valve member comes into contact with when the valve is in use.

The valve housing can be made from a polymeric material. An example of a polymeric material from which the valve housing might be made could include an engineering polymer such as a polyetheretherketone (PEEK).

The valve housing will frequently be made from a metal. Examples of metals from which the housing might be made include certain steels, especially stainless steels, and aluminium and its alloys. The material from which the valve housing is made will be selected so that the housing can withstand the conditions which it is exposed to when the valve is in use, including the operating temperatures and pressures of the valve, and materials which the housing comes into contact with when the valve is in use.

The valve housing comprises multiple parts which can be assembled together. The valve housing can comprise a first part which defines at least part of the chamber for the valve member, and a second part which, when assembled with the first part, closes the chamber to retain the valve member inside. First and second parts of a valve housing can be retained together in such a way that they can be disassembled, for example to allow replacement of the valve member. First and second parts of a valve housing can be assembled by means of cooperating threads on the first and second parts respectively. First and second parts of a valve housing can be assembled by means of an appropriate clamp, for example by means of tie rods.

When the valve body comprises two or more parts, a first part of the bypass channel can be provided in one of the parts and a second part of the bypass channel can be provided in another of the parts. When the bypass channel is provided by two or more bores in the valve body, each of those bores can be provided by a partial bore in one of the parts of the valve body and a partial bore in another of the parts. The parts of the valve body can be aligned so that the partial bores in the parts of the valve body are aligned exactly. At least one of the parts of the valve body can have a groove (for example an annular groove) on the face which contacts another part, with the partial bores terminating in that groove. The partial bores on the other part can be aligned with the groove rather than having to be aligned with the partial bores that terminate in the groove.

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

Figure l is a sectional elevation through a one-way valve according to the invention.

Figure 2 is a sectional elevation through the inlet end part of the valve shown in

Figure 1.

Figure 3 is an end view of the inlet end part shown in Figure 2, from the right hand side of the part as shown in Figure 2.

Figure 4 is a sectional elevation through the outlet end part of the valve shown in

Figure 1.

Figure 5 is an end view of the inlet end part shown in Figure 4, from the left hand side of the part as shown in Figure 4.

Referring to the drawings, Figure 1 shows a one-way valve 2 in which a valve body 4 has an inlet end part 6 and an outlet end part 8. The inlet end part 6 defines an inlet 10 through which a fluid can enter the valve to flow through the valve in the normal direction. The inlet end part has an external cylindrical surface 12 which is threaded for connection of the inlet end part to a conduit for supply of fluid to the valve. The inlet end part has an O-ring 14 in an axially facing groove 16 for forming a seal to such a conduit.

The inlet end part 6 has a generally conical valve seat surface 18 which faces towards the outlet end part of the valve body when the inlet and outlet end parts are assembled together. The inlet end part has a cylindrical chamber 20 having a circular cross-section extending along its length from the conical valve seat surface 18 towards the outlet end part of the valve body. The angle between the valve seat surface and the axis of the valve (which is the axis of the cylindrical chamber) is about 45°.

The inlet end part 6 has twelve bores 22 extending parallel to one another along the length of the inlet end part, arranged around the cylindrical chamber 20. The bores are open at the end 24 of the inlet end part which faces towards the outlet end part where they open into a groove 32 that is provided on the end face. The bores terminate at their opposite ends at an annular groove 26 through which they communicate with the chamber 20 and the inlet 10. The edge face of the groove 26 which faces the inlet overlaps the valve seat surface 18. The edge face of the groove 26 which faces the outlet overlaps the cylindrical surface which defines the chamber 20. The edge faces of the groove are planar and are arranged approximately perpendicular to the axis of the valve.

The inlet end part 6 has an external cylindrical surface which has a stepped portion 28 at its end which faces towards the outlet end part 8. An O-ring 30 is provided in the groove 32 on the end face of the inlet end part, adjacent the stepped portion of the external surface.

The outlet end part 8 defines an outlet 40 through which a fluid flowing through the valve in the normal direction can flow from the valve into a conduit. The outlet end part has an external cylindrical surface 42 which is threaded for connection of the outlet end part to a conduit for fluid flowing through the valve in the normal direction to flow from the valve. The outlet end part has an O-ring 44 in an axially facing groove 46 for forming a seal to such a conduit.

The outlet end part 8 has a plate 48 which faces the inlet end part when the inlet and outlet end parts are assembled together. The plate is arranged perpendicular to the axis of the valve defined by the cylindrical chamber 20. The plate has five apertures 50 formed in it, arranged in a circular array around the axis of the valve.

The outlet end part has twelve bores 52 extending parallel to one another, arranged in a circular array around the array of five apertures. The spacing of the twelve bores 52 in the outlet end part is identical to the spacing of the twelve bores 22 in the inlet end part. The bores are open at the end 54 of the outlet end part which faces towards the inlet end part. The bores terminate at their opposite ends at an annular groove 56 which communicates with the outlet 40. The edge faces of the groove 56 are planar and are arranged approximately perpendicular to the axis of the valve. The outlet end part 8 has a circumferential flange 58 which is sized so that the stepped portion 28 of the inlet end part 6 is a sliding fit inside the flange. The O-ring 30 in the groove 32 on the end face of the inlet end part is compressed between the end faces of the inlet and outlet end parts when the parts are fully assembled.

The inlet end part 6 has a shoulder groove 70 facing away from the outlet end part and the outlet end part 8 has a shoulder groove 72 facing away from the inlet end part. The shoulder grooves 70, 72 on the inlet and outlet end parts can receive a tie-rod or other clamp to retain the end parts together with the stepped portion 28 of the inlet end part 6 received within the flange 58 on the outlet end part and the O-ring 30 in the groove 32 on the end face of the inlet end part compressed between the end faces of the inlet and outlet end parts. The plate 48 on the outlet end part 8 contacts the end face of the inlet end part 6 around the cylindrical chamber 20. A gasket 74 can be provided on the plate to form an annular seal to the end face of the inlet end part, around the five apertures 50 in the plate.

The inlet and outlet end parts 6, 8 are assembled in such a way that the groove 32 in the end face of the inlet end part is aligned with the twelve bores 52 in the outlet end part, so that the bores 22 in the inlet end part communicate with the bores 52 in the outlet end part through the groove 32, and the bores provide a bypass channel between the inlet 10 and the outlet 40, which includes the annular groove 26 in the inlet end part and the annular groove 56 in the outlet end part. The circumferentially extending opening to the groove 26 in the inlet end part is a first channel port. The circumferentially extending opening to the groove 56 in the outlet end part is a second channel port. Fluid can flow from the inlet 10 to the outlet 40 through the bypass channel provided by the first channel port provided by the groove 26 in the inlet end part, the twelve bores 22 in the inlet end part, the groove 32 in the end face of the inlet end part, the twelve bores 52 in the outlet end part, and the second channel port provided by the groove 56 in the outlet end part.

The provision of the groove 32 to allow fluid communication between the twelve bores 22 in the inlet end part and the twelve bores 52 in the outlet end part removes the need for the bores in the inlet end parts to be aligned precisely. The valve includes a valve member 80 which is a spherical rubber ball. It is located in the cylindrical chamber 20 within the inlet end part. The spherical ball can translate in the chamber between an open position in which the valve member contacts the plate 48 and a closed position in which the valve member contacts the valve seat surface 18.

In use, the valve 2 is connected to an inlet conduit through which a fluid (which could be a gas or a liquid) is supplied to the inlet 10, and to an outlet conduit through which fluid flows away from the valve after discharge from the outlet 40. Fluid flows through the valve when the fluid pressure in the inlet 10 is greater than the pressure in the outlet 40.

The valve member tends to move away from its closed position in which it contacts the valve seat surface 18 (as shown in Figure 1) towards its open position in which it contacts the plate 48 because of that pressure differential. Such flow through the valve is referred to as flow in the normal direction.

When the valve is open, the valve member 80 is pressed, as a result of the pressure being higher in the inlet than in the outlet, against the plate 48. Fluid can flow from the inlet 10 to the outlet 40 through annular groove 26 in the inlet end part into the twelve bores 22 in the inlet end part, and then into the aligned twelve bores 52 in the outlet end part and the annular groove 56 in the outlet end part for discharge from the valve through the outlet 40.

The valve member 80 is a close fit in the cylindrical chamber 20 so that the space within the chamber around the valve member for fluid to flow through the chamber is small.

The valve closes when the fluid pressure in the outlet 40 is greater than the fluid pressure in the inlet 10. The valve member 80 moves because of the pressure differential across it from the open position in which it contacts the plate 48 to the closed position in which it contacts the valve seat surface 18 (as shown in Figure 1). The valve member is exposed on its side which faces the outlet 40 to pressurised fluid in the outlet because of the five apertures 50 in the plate. The close fit of the valve member in the cylindrical chamber means that the pressure differential across the valve member tends primarily to cause the valve member to translate to the closed position rather than causing fluid to flow within the chamber around the valve member between the valve member and the internal wall of the chamber. The valve member moves quickly to the closed position. It then prevents flow of fluid through the valve in the reverse direction from the outlet towards the inlet, whether through the chamber or through the twelve aligned bores.

Dimensions and other characteristics of a typical valve are set out below as an example:

The diameter of each of the twelve bores in the inlet and outlet end parts can be 5 mm, so that the cross-sectional area of each of the twelve bores is 235.6 mm ² . The width of each of the annular grooves 26, 56 is 3 mm. The diameter of the chamber at the opening to the annular groove 26 in the inlet end part is 19.55 mm. The diameter of the outlet at the opening to the annular groove 56 in the outlet end part is 18 mm. The area of the opening to the twelve bores that is provided by the annular groove 26 in the inlet end part is therefore 184.3 mm ² , and the area of the opening to the twelve bores that is provided by the annular groove 56 in the outlet end part is 169.6 mm ² .

The diameter of the cylindrical chamber 20 can be 19.55 mm and the diameter of the spherical valve member can be 19.3 mm. The cross-sectional area of the chamber is therefore 300.2 mm ² and the cross-sectional area of the valve member is 292.6 mm ² . The area of the flow path for fluid to flow through the chamber when the valve member is in its open position is 7.6 mm ² , and the ratio of the diameter of the valve member to the diameter of the chamber is then 0.99.

The ratio of the cross-sectional area of the valve member to the minimum cross-sectional area of the bypass channel (which is the area of the opening to the twelve bores that is provided by the annular groove in the outlet end part) is 1.73.

The ratio of the cross-sectional area of the flow path for fluid flowing through the chamber when the valve member is in its open position to the minimum cross-sectional of the flow path for fluid flowing through the bypass channel is then 0.045.

The distance moved by the valve member as it moves between its open and closed positions can be 3 mm. The ratio of the diameter of the chamber to the distance moved by the valve member between its open and closed positions is about 6.3.

When the total length of each of the twelve bores is 18 mm, the length of the flow path for fluid to flow along the bypass channel provided by the twelve bores between the first channel port provided by the groove 26 in the inlet end part and the second channel port provided by the groove 56 in the outlet end part is about 24 mm.

The one-way valve provided by the invention can be used in applications in which it is required to restrict flow of fluid to flow in one direction. The fluid might be a liquid. Frequently the fluid will be a gas.

In particular, the valve can be used in a compressed gas system where it is desirable to maintain pressure in one or more components of the system when pressure to that or those components is shut off, whether accidentally or as part of the normal operation of the system.

An example of an application for the valve is a compressed gas system in which the valve can ensure that downstream components in the system can remain pressurised when the compressor is shut down and pressure between the compressor and the valve is vented.

The valve might be used in apparatus which makes use of pressure swing adsorption technology such as a compressed air dryer or a gas separation device (for example a nitrogen generator). A one-way valve can help to maintain pressure in an adsorption chamber of a multi-chamber PSA apparatus.