FIELD

The present disclosure relates to a downhole valve apparatus such as might be used to close or restrict a downhole flow path, for example a downhole ball valve apparatus.

BACKGROUND

Wellbore infrastructure and operations often require the use of valves to provide flow and/or pressure control. For example, valves may be used to control production and/or injection flow rates and pressures, to isolate sections of the wellbore, to contain wellbore pressure and fluids while topside or in-well operations are performed, to facilitate pressure testing, to facilitate tool actuation and the like.

In many cases large pressure differentials may be present across a wellbore valve. These large pressure differentials may result in significant stresses on the valve components during operation, particularly where there are small contact areas between components resulting in point loading. Therefore, there is a clear interest for all operators to utilise wellbore equipment which is robust and reliable, especially when any failure of the valve components may prevent wellbore operations being carried out or may establish a blockage in a completion.

SUMMARY

An aspect of the present disclosure relates to a downhole valve apparatus. The apparatus may comprise a valve member, an interface member and a valve operator. The valve member may have an open position and a closed position. The valve member may be rotatable around a rotation axis of the valve member between the open and closed positions. The interface member may comprise a drive recess. The valve operator may be cooperable with the interface member to provide rotation of the valve member around the rotation axis between the open and closed positions. The valve operator may comprise a valve member engaging portion. The valve member engaging portion may be rotatably mounted with the valve member. The valve operator may comprise a drive recess engaging portion. The drive recess engaging portion may be slidably mounted with the drive recess. The drive recess engaging portion and the drive recess may comprise complementary engagable surfaces. The valve operator, in particular the complementary engagable surfaces, may provide a robust interface between the interface member and the valve member to prevent stress concentrations occurring between the respective components.

An aspect of the present disclosure relates to a downhole valve apparatus comprising: a valve member having an open position and a closed position, the valve member rotatable around a rotation axis of the valve member between the open and closed positions; an interface member comprising a drive recess; and a valve operator cooperable with the interface member to provide rotation of the valve member around the rotation axis between the open and closed positions, the valve operator comprising a valve member engaging portion rotatably mounted with the valve member and a drive recess engaging portion slidably mounted with the drive recess; wherein the drive recess engaging portion and the drive recess comprise complimentary engagable surfaces.

The complimentary engagable surfaces may comprise an end surface of the drive recess and an operation surface of the drive recess engaging portion of the valve operator. The end surface and the operation surface may be cooperable to provide rotation of the valve member around the rotation axis between the open and closed positions. The complementary surfaces may provide surface contact between the valve operator and the interface member sufficient to distribute stresses on the surfaces such that the components can withstand large pressure differentials.

The valve operator may slide relative to the drive recess during rotation of the valve member. The drive recess may comprise an open side to permit the valve operator to slide relative to the drive recess during rotation of the valve member.

The end surface and the operation surface may maintain sliding contact during rotation of the valve member.

The valve member may comprise a hole. The valve member engaging portion of the valve operator may be rotatably mounted within the hole. An outer surface of the valve member engaging portion of the valve operator and an inner surface of the hole may maintain rotatable contact during operation of the valve apparatus. The inner surface of the hole and the outer surface of the valve member engaging portion of the valve operator may be correspondingly shaped to maintain rotatable contact across substantially the entire area of the inner and outer surfaces. The hole may be cylindrical. The valve member engaging portion of the valve operator may be cylindrical.

The hole may be offset from the rotation axis. The hole may be eccentrically located with respect to the rotation axis.

The location of engagement between the valve member and the valve operator may facilitate the valve operator imparting a moment on the valve member, therefore providing a simple actuation mechanism having a single area of interaction for translating the axial movement of the interface member to rotation of the valve member around the rotation axis.

The valve member and the interface member may be configured for relative movement in a lost motion movement phase without rotation of the valve member. By providing a lost motion movement phase, the valve apparatus may be used to operate or actuate a sub-assembly of the valve apparatus prior to actuation of the valve member, for example an equalisation assembly.

The drive recess may be elongate.

The drive recess engaging portion of the valve operator may be axially slidable within the drive recess during the lost motion movement phase.

The complimentary engagable surfaces may comprise a longitudinal surface of the drive recess engaging portion of the valve operator and an elongate surface of the drive recess. The longitudinal surface may be transverse to the operation surface of the drive recess engaging portion of the valve operator. The elongate surface may be transverse to the end surface of the drive recess.

The drive recess may be rectilinear.

The drive recess engaging portion of the valve operator may be rectilinear.

The longitudinal surface of the drive recess engaging portion of the valve operator and the elongate surface of the drive recess may maintain sliding contact in the lost motion movement phase. The longitudinal surface and the elongate surface may temporarily lose contact during rotation of the valve member between the open and closed positions.

The open side of the drive recess may be a side of the drive recess opposite the elongate surface of the drive recess.

An axial length of the elongate surface of the drive recess may determine the extent of the lost motion movement phase. The elongate surface of the drive recess may have an axial length substantially greater than an axial length of the longitudinal surface of the drive recess engaging portion of the valve operator. The difference in axial length between the elongate surface and the longitudinal surface may determine the extent of the lost motion movement phase.

The end surface of the drive recess and the operation surface of the drive recess engaging portion of the valve operator may not be in contact during the lost motion movement phase. The end surface and the operation surface may be in contact before and/or after the lost motion movement phase.

The end surface of the drive recess may comprise a first end surface and a second end surface.

The operation surface of the drive recess engaging portion of the valve operator may comprise a first operation surface and a second operation surface.

The first end surface of the drive recess may cooperate with the first operation surface of the drive recess engaging portion of the valve operator to rotate the valve member from the open position to the closed position. The second end surface of the drive recess may cooperate with the second operation surface of the drive recess engaging portion of the valve member to rotate the valve member from the closed position to the open position.

Prior to the lost motion movement phase one of the first and second operation surfaces of the drive recess engaging portion of the valve operator may be in contact with a corresponding one of the first and second ends of the drive recess. Following the lost motion movement phase the other one of the first and second operation surfaces of the drive recess engaging portion of the valve operator may be in contact with the corresponding other one of the first and second end surfaces of the drive recess. During the lost motion movement phase the second operation surface of the drive recess engaging portion of the valve operator may not be in contact with the second end of the drive recess, and the first operation surface of the drive recess engaging portion of the valve operator may not be in contact with the first end of the drive recess.

The valve member may comprise a limit stop. The interface member may comprise a stop recess. The limit stop may be moveable in the stop recess. The limit stop may be engagable with the stop recess to prevent over rotation and support the valve member at a predetermined extent of rotation.

The drive recess and the stop recess may define a rail therebetween. The elongate surface of the drive recess may be a surface of the rail. The stop recess may comprise a support surface. The support surface may be a surface of the rail. The support surface may be a surface of the rail opposite the elongate surface.

The stop recess may comprise an open side. A portion of the limit stop may extend through the open side of the stop recess. The open side of the stop recess may be a side of the stop recess opposite the support surface of the stop recess.

The limit stop may comprise a stop surface. The stop surface may be engagable with the support surface to support the valve member at a predetermined extent of rotation. The support surface and the stop surface may have complementary engaging profiles. The contact area between the support surface and stop surface may be sufficient to distribute stresses on the surfaces such that the components can withstand large forces.

The stop surface may maintain sliding contact with the support surface during the lost motion movement phase.

The stop recess may have an axial length greater than an axial length of the drive recess.

The stop recess may be positioned axially relative to the drive recess to permit the stop surface to engage the support surface when the end surface of the drive recess and the operation surface of the drive recess engaging portion of the valve operator are cooperating and the valve member has rotated the predetermined extent. Engagement of the stop surface and the support surface may prevent over rotation of the valve member.

The rail may support the limit stop and the valve operator.

The stop recess and the drive recess may share a line of symmetry.

The stop surface of the limit stop may comprise a first stop surface and a second stop surface. An angle defined between the first and second stop surfaces may correspond to an angle of rotation of the valve member between the open and closed positions. The first stop surface may engage the support surface to support the valve member in the closed position. The second stop surface may engage the support surface to support the valve member in the open position.

The valve member may be a ball valve.

The valve member may comprise a throughbore. The throughbore may extend transverse to the rotation axis.

The valve member may comprise a truncated face. The truncated face may intersect the rotation axis. The truncated face may be transverse to the rotation axis. The limit stop may be shaped with a portion of the truncated face. The portion of the truncated face may be truncated to a lesser extent than the remainder of the truncated face, the portion of the truncated face thus forming the limit stop. The portion of the truncated face may be a quadrant of the truncated face. Wherein the portion of the truncated face is a quadrant of the truncated face, the valve member may rotate through 90 degrees between the open and closed positions.

The truncated face may comprise the hole for rotatably receiving the valve member engaging portion of the valve operator. The hole may be located in an opposing portion of the truncated face to the limit stop. Wherein the portion of the truncated face is a quadrant of the truncated face, the hole may be located in an opposing quadrant of the truncated face.

The valve member may be formed of a first material. The valve operator may be formed of a second material. The first material may be different to the second material. Because the valve member and the valve operator are separate components, the material used for each of the valve member and the valve operator may be optimised for that component.

The valve apparatus may comprise an actuator assembly. The actuator assembly may comprise the interface member.

The valve apparatus may comprise a guide assembly. The guide assembly may axially locate the valve member. The valve member may be in rotatable contact with the guide assembly. The guide assembly may act as a journal for the valve member, to support the valve member as it rotates between the open and closed positions. A seal may be provided on a portion of the guide assembly. The guide assembly may comprise a biasing arrangement to bias the valve member towards the seal.

The actuator may be moveable relative to the guide assembly to cause relative movement between the interface member and the valve member.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic section view of a downhole valve apparatus in an open configuration;

Figure 2 is a schematic section view of the downhole valve apparatus of Figure 1 in a closed configuration; Figure 3 is a perspective view of an interface member of the downhole valve apparatus of Figure 1;

Figure 4 is a perspective view of a valve operator of the downhole valve apparatus of Figure 1;

Figure 5 is a plan view of a valve member of the downhole valve apparatus of Figure 1 ;

Figure 6 is a perspective view of the valve member of Figure 5;

Figure 7 is a perspective assembly view of first and second interface members according to Figure 3, first and second valve operators according to Figure 4 and the valve member of Figure 5;

Figure 8A is an elevation view of the downhole valve apparatus of Figure 1 in the closed configuration;

Figure 8B is an elevation view of the downhole valve apparatus of Figure 1 following a lost motion movement phase;

Figure 8C is an elevation view of the downhole valve apparatus of Figure 1 during rotation of the valve member;

Figure 8D is an elevation view of the downhole valve apparatus of Figure 1 in the open configuration;

Figure 9A is an elevation view of the downhole valve apparatus of Figure 1 in the open configuration;

Figure 9B is an elevation view of the downhole valve apparatus of Figure 1 following a lost motion movement phase;

Figure 9C is an elevation view of the downhole valve apparatus of Figure 1 during rotation of the valve member; and

Figure 9D is an elevation view of the downhole valve apparatus of Figure 1 in the closed configuration.

DETAILED DESCRIPTION

Figure 1 is a schematic sectional view of a valve apparatus 10. The valve apparatus 10 may be suitable for use in multiple environments, industries and applications. In the present exemplary description, the valve apparatus 10 is intended for use within a wellbore, and as such may be defined as a downhole valve apparatus 10.

In reference to Figures 1 and 2, the valve apparatus 10 includes a housing 12 which defines a longitudinal flow path 14. A rotatable valve member 20 is provided within the housing 12 to control flow along the flow path 14. The valve member 20 has a rotation axis 24 which extends through the centre of the valve member 20. The valve member 20 is generally ball shaped and comprises a throughbore 22 that extends transverse to the rotation axis 24 between diametrically opposed openings 26a, 26b formed in the outer surface of the valve member 20. The valve member 20 is rotatable about the rotation axis 24 between an open position and a closed position. In the open position the throughbore 22 is generally aligned with the flow path 14, thereby permitting flow along the flow path 14, as illustrated in Figure 1. In the closed position the throughbore 22 is generally not aligned with the flow path 14, thereby restricting flow along the flow path 14, as illustrated in Figure 2.

The apparatus 10 further includes an actuation assembly 46 and a guide assembly 52, both mounted within the housing 12. The valve member 20 and the guide assembly 52 are mounted within the actuation assembly 46. The guide assembly 52 comprises a valve seat sleeve assembly 45 and an axial locating sleeve assembly 47. The valve member 20 is mounted axially between and in rotatable contact with the valve seat sleeve assembly 45 and the axial locating sleeve assembly 47 such that the guide assembly 52 acts as a journal, maintaining the location of the valve member 20 as the valve member 20 rotates between the open and closed positions. The valve seat sleeve assembly 45 includes a valve seat 51 at an end of the valve seat sleeve assembly 45 proximal the valve member 20. The valve seat 51 includes a seat seal (not shown). The axial locating sleeve assembly 47 includes a spring (not shown) to bias the axial locating sleeve assembly 47 towards the valve member 20 and maintain contact between the valve member 20 and the valve seat sleeve assembly 45 such that the valve member 20 and the seat seal form a seal. When the valve member 20 is in the closed position, the valve member 20 and the seal act to isolate one side of the valve member 20 from the other side, thereby allowing a pressure differential to occur across the valve member 20.

The actuation assembly 46 is axially moveable relative to the guide assembly 52, and thereby relative to the valve member 20. In other examples, the guide assembly 52 may be axially moveable relative to the actuation assembly 46 or the actuation assembly 46 and the guide assembly 52 may be axially moveable relative to each other. Relative movement between the actuation assembly 46 and the valve member 20 causes the valve member 20 to rotate between its open position and closed positions, as will be described in greater detail below with regard to the operation of the valve apparatus 10. The actuation assembly 46 includes first and second interface members 60a, 60b. The first and second interface members 60a, 60b are mounted on diametrically opposing sides of the valve member 20, and axially extend to either side of the valve member 20, such that the first and second interface members 60a, 60b intersect the rotation axis 24. The first and second interface members 60a and 60b are correspondingly formed and mirror each other when assembled in the valve apparatus 10.

An exemplary interface member 60 is described with reference to Figure 3. The interface member 60 has a generally plate form and may be defined as a ball plate. The interface member includes axial end portions 67, 68 for connecting the interface member with adjacent components of the actuation assembly 46. The interface member 60 includes a drive recess 100 and a stop recess 102. The interface member 60 further includes a rail 97 defined between the drive recess 100 and the stop recess 102. The drive recess 100 and the stop recess 102 are rectilinear and elongate. The axial length LD of the drive recess 100 is less than the axial length L _s of the stop recess 102. The axial mid-point of the drive recess 100 is axially aligned with the axial midpoint of the stop recess 102 on a line of symmetry S. The drive recess 100 and stop recess 102 are both symmetrical across the line of symmetry S. The drive recess 100 and stop recess 102 interrupt opposite edges of the interface member 60 such that the drive recess 100 and the stop recess 102 are both enclosed on three sides and open on a fourth side for reasons that will become apparent from the description below of the operation of the valve apparatus 20. The drive recess 100 has first and second end surfaces 101a, 101b and an elongate surface 99. The stop recess 102 has first and second end surfaces 105a, 105b and an elongate surface referred to as a support surface 103. The elongate surface 99 of the drive recess 100 and the support surface 103 of the stop recess 102 are side surfaces of the rail 97.

The valve apparatus 10 further includes first and second valve operators 64a, 64b (see, for example, Figure 7). As will be explained below with regard to the operation of the valve apparatus 10, the valve operators are provided to translate axial motion of the actuation assembly 46 to rotation of the valve member 20 between the open and closed positions. The first and second valve operators 64a, 64b are correspondingly formed and mirror each other when assembled in the valve apparatus 10.

An exemplary valve operator 64 is described with reference to Figure 4. The valve operator 64 comprises a drive recess engaging portion 90 in the form of a head and a valve member engaging portion 92 in the form of a pin. The head 90 is generally rectilinear in shape, whereas the pin 92 is generally cylindrical in shape. The head comprises first and second operation surfaces 91a, 91b and a longitudinal surface 93 extending between the end surfaces 91a, 91b.

As described above, the valve member 20 includes a throughbore 22 extending between openings 26a, 26b. In reference to Figures 5 and 6, the openings 26a, 26b in the valve member 20 form first and second truncations of the valve member 20 parallel to the rotation axis 24. The valve member 20 further comprises third and fourth truncations in the form of truncated surfaces 76a, 76b that intersect the rotation axis 24. Only the truncated surface 76a is visible in Figures 5 and 6; however the truncated surface 76b is generally formed in a corresponding mirrored manner to truncated surface 76a.

Each of the truncated surfaces 76a, 76b comprises a limit stop 82. As will be explained below with regard to the operation of the valve apparatus 10, the limit stop 82 cooperates with the stop recess 102 of the interface member 60 to restrict the extent of rotation of the valve member 20 between the open and closed positions, and prevent over rotation of the valve member 20.

As can be seen in Figure 6, the limit stop 82 is a continuation of a portion of the truncated surface 76. The limit stop 82 is truncated to a lesser extent than the remainder of the truncated surface 76. For reasons that will become apparent from description below of the operation of the valve apparatus 10, the difference in the extent of truncation of the limit stop 82 and the remainder of the truncated surface 76 corresponds to a depth of the stop recess 102 in the interface member 60.

The limit stop 82 defines first and second stop surfaces 84a, 84b. As can be seen in Figure 5, the limit stop 82 is a continuation of a quadrant of the truncated surface 76, such that the first and second stop surfaces 84a, 84b are angled at generally 90 degrees relative to each other. The angle defined between the first and second stop surfaces 84a, 84b corresponds to the angle of rotation between the open and closed positions of the valve member 20. In other examples the limit stop may be a continuation of any portion of the truncated surface that provides first and second stop surfaces at a respective angle to each other corresponding to a desired angle of rotation between the open and closed positions of the valve member.

Further referring to Figures 5 and 6, each of the truncated surfaces 76a, 76b comprises a hole 80 which is generally cylindrical in shape. As will be described in further detail with regard to the operation of the valve apparatus 10, the hole 80 rotatably receives the pin 92 of the valve operator 64 in order to translate axial movement of the interface member 60 to rotation of the valve member 20. The hole 80 is offset from the rotation axis 24 of the valve member 20. In particular, the hole 80 is located in the opposing quadrant of the truncated face 76 to the limit stop 82. In other examples the hole 80 may be located in an appropriate opposing portion of the truncated face 76 to the limit stop 82 determined by the angle between the first and second stop surfaces 84a, 84b of the limit stop 82.

The first and second interface members 60a, 60b, the first and second valve operators 64a, 64b and the valve member are assembled as shown in Figure 7. The first and second valve operators 64a, 64b are located respectively between the first and second interface members 60a, 60b and the valve member 20. The configuration of the first interface member 60a, the first valve operator 64a and the first truncated surface 76a of the valve member 20 is described below. The second interface member 60b, second valve operator 64b and second truncated surface 76b of the valve member 20 are configured in a corresponding mirrored manner.

The pin 92 of the valve operator 64 rotatably engages the hole 80 in the valve member 20. The corresponding cylindrical shapes of the hole 80 and the pin 92 facilitate such rotation. The valve operator 64 is therefore engaged with the valve member 20 at a location offset from the rotation axis 24 through the centre of the valve member 20.

The head 90 of the valve operator 64 is axially slidable within the drive recess 100. The corresponding rectilinear shapes of the head 90 and the drive recess 100 facilitate such axial sliding motion. The first and second operation surfaces 91a, 91b of the head 90 of the valve operator 64 are engagable with the respective first and second end surfaces 101a, 101b of the drive recess 100 to provide rotation of the valve member 20, as will be described in detail below with regard to the operation of the valve apparatus 10.

The limit stop 82 of the valve member 20 is received by and movable within the stop recess 102 of the interface member 60. The relative positioning and length of the drive recess 100 and the stop recess 102 allows one of the first and second stop surfaces 84a, 84b of the limit stop 82 to abut the support surface 103 of the stop recess 102 when the valve member 20 is in its respective defined open and closed positions. When the valve member 20 is in the closed position, the first stop surface 84a will abut the support surface 103 of the stop recess 102. When the valve member 20 is in the open position, the second stop surface 84b will abut the support surface 103 of the stop recess 102. The interaction between the limit stop 82 and the stop recess 102 prevents the valve member 20 from over rotating beyond the open and closed positions, and supports the valve member 20 in the open and closed positions.

The drive recess 100 and stop recess 102 are elongate such that the valve operator 90 can slide along the drive recess 100 between the first and second end surfaces 101a, 101b, to permit relative movement between the valve member 20 and the interface members 60 without rotation of the valve member 20. At the same time, the limit stop 82 slides along the stop recess 102. As such, lost motion is provided between the valve member 20 and interface members 60, such that the valve member 20 may remain in the open or closed position during a lost motion movement phase of the valve apparatus 10. Both the limit stop 82 and the valve operator 90 are engaged with and supported by the rail 97 during lost motion, therefore a robust interface between the actuation assembly 46 and the valve member 20 is provided.

The lost motion allows the relative movement of the actuator assembly 46 and the guide assembly 52 to actuate another sub-system of the valve apparatus 10 over the lost motion movement phase without corresponding actuation of the valve member 20. For example the actuator assembly 46 may actuate a pressure equalisation system over the lost motion movement phase; the pressure equalization system may become opened during this movement phase, while the valve member remains closed. By equalising pressure across the valve member prior to actuating the valve member, the stresses on the components of the valve member may be reduced and/or the force required to actuate the valve member may be reduced.

The extent of lost motion is determined by the length LD of the drive recess 100 and the distance that the head 90 of the valve operator 64 can travel within the drive recess 100. Following the lost motion movement phase one of the operation surfaces 91 of the head 90 of the valve operator 64 will abut one of the end surfaces 101 of the drive recess 100. Continued relative movement of the first and second sleeve assemblies 46, 52 will provide a second and sequential valve actuation movement phase during which the valve operator 64 applies a moment to the valve member 20 to rotate the valve member 20.

In an alternative example, the drive recess and stop recess may not be configured to provide lost motion. The drive recess may be correspondingly sized in axial length to the axial length of the head of the valve operator, to receive and axially fix the head of the valve operator. In such an example, the second movement phase is the only movement phase. Operation of the actuation assembly 46 actuating the valve member 20 from a closed position to an open position will now be described with reference to Figures 8A- 8D.

Figure 8A illustrates the valve member 20 in the closed position wherein the throughbore 22 is transverse to the flow path (not shown). The first stop surface 84a abuts the support surface 103 to support the valve member 20 in the closed position. The head 90 of the valve operator 64 is engaged with the drive recess 100, the first operation surface 91a of the head 90 contacting the first end surface 101a of the drive recess and the longitudinal surface 93 of the head 90 contacting the elongate surface 99 of the drive recess 100. Relative movement between the actuator assembly 46 and the guide assembly 52 of the valve apparatus 10 causes relative axial movement between the valve member 20 and the interface member 60 in a first motion phase. The limit stop 82 slides within the stop recess 102, the first stop surface 84a maintaining contact with the support surface 103. The head 90 of the valve operator 64 slides within the drive recess 100, the first operation surface 91a of the head 90 moving out of contact with the first end surface 101a, and the longitudinal surface 93 of the head 90 maintaining sliding contact with the elongate surface 99 of the drive recess 100. The rail 97 is captured between the limit stop 82 and the valve operator 64 as the interface member 60 and the valve member 20 move relative to each other. This provides a robust and stable seat for the valve member 20. The rectilinear form of the drive recess 100 and the head 90 provides a substantial contact surface area for distributing loads transferred between the valve member and the actuation assembly during lost motion, thereby reducing stress concentrations. The corresponding form of the first stop surface 84a and the support surface 103 further contributes to the distribution of loads transferred between the valve member and the actuation assembly.

After a predetermined extent of lost motion, the second operation surface 91b of the head 90 engages the second end surface 101b of the drive recess 100, as shown in Figure 8B.

Continued relative axial movement between the actuator assembly 46 and the guide assembly 52 causes the valve member 20 to rotate around the rotation axis 24, as shown in Figure 8C. Axial movement of the interface member 60 results in axial movement of the valve operator 64. As the valve operator 64 is engaged with the valve member 20 at a location offset from the rotation axis 24 of the valve member 20, axial movement of the valve operator 64 provides a moment around the rotation axis 24 of the valve member 20. Accordingly, the valve operator 64 being moved axially by the interface member 60 of the actuation assembly 46 results in rotation of the valve member 20 around the rotation axis 24 from the closed position to the open position.

As the valve member 20 rotates around the rotation axis 24, the valve operator 64 moves transversely relative to the drive recess 100. The open side of the drive recess 100 receives the head 90 of the valve operator 64 during this transverse movement. The longitudinal surface 93 of the head moves temporarily out of contact with the elongate surface 99 of the drive recess 100 whilst the second operation surface 91b of the head 90 and the second end surface 101b of the drive recess 100 maintain sliding contact. The rectilinear form of the drive recess 100 and the head 90 provides a substantial contact surface area for distributing loads transferred between the actuation assembly 46 and the valve member 20 during rotation of the valve member, thereby reducing stress concentrations. The alignment of the rotation axis 24 of the valve member 20 and a central plane of the interface member 60 is maintained by the guide assembly 52.

With continued reference to Figure 8C, as the valve member 20 rotates the first stop surface 84a moves out of contact with the support surface 103 and the second stop surface 84b moves into contact with the support surface 103.

As can be seen in Figure 8D, once the second stop surface 84b abuts the support surface 103, continued rotation of the valve member 20 is prevented by the interaction between the limit stop 82 and the stop recess 102. In this position, the longitudinal surface 93 of the head has returned to contacting the elongate surface 99 of the drive recess. The rail 97 is again trapped between the limit stop 82 and the valve operator 64. In preventing over rotation of the valve member 20, forces are transferred between the limit stop 82 and the rail 97. These forces are balanced by opposing forces transferred between the valve operator 64 and the rail 97. The valve member 20 is now supported in the open position with the throughbore 22 aligned with the flow path.

Operation of the actuation assembly 46 actuating the valve member 20 from an open position to a closed position will now be described with reference to Figures 9A- 9D.

With reference to Figure 9A, the valve member 20 is initially in the open position wherein the throughbore 22 is aligned with the flow path (not shown). The second stop surface 84b abuts the support surface 103 to support the valve member 20 in the open position. The head 90 of the valve operator 64 is engaged with the drive recess 100, the second operation surface 91b of the head 90 in contact with the second end surface 101b of the drive recess 100, and the longitudinal surface 93 of the head 90 in contact with the elongate surface 99 of the drive recess 100. Relative movement between the actuation assembly 46 and the guide assembly 52 of the valve apparatus 10 causes relative axial movement between the valve member 20 and the interface member 60 in a first motion phase without rotation of the valve member 20. The limit stop 82 slides within the stop recess 102, the second stop surface 84b maintaining contact with the support surface 103. The head 90 of the valve operator 64 slides within the drive recess 100, the second operation surface 91b of the head 90 moving out of contact with the second end surface 101b of the drive recess 100 and the longitudinal surface 93 of the head 90 maintaining sliding contact with the elongate surface 99 of the drive recess 100. The rail 97 is captured between the limit stop 82 and the valve operator 64 as the interface member 60 and the valve member 20 move relative to each other. This provides a robust and stable seat for the valve member 20. The rectilinear form of the drive recess 100 and the head 90 provides a substantial contact surface area for distributing loads transferred between the valve member 20 and the actuation assembly 46 during lost motion, thereby reducing stress concentrations. The corresponding form of the second stop surface 84b and the support surface 103 further contributes to the distribution of loads transferred between the valve member and the actuation assembly.

After a predetermined extent of lost motion, the first operation surface 91a of the head 90 engages the first end surface 101a of the drive recess 100, as shown in Figure 9B.

Continued relative movement between the actuation assembly 46 and the guide assembly 52 causes the valve member 20 to rotate around the rotation axis 24, as shown in Figure 9C. Axial movement of the interface member 60 results in axial movement of the valve operator 64. As the valve operator 64 is engaged with the valve member 20 at a location offset from the rotation axis 24 of the valve member 20, axial movement of the valve operator 64 provides a moment around the rotation axis 24 of the valve member 20. Accordingly, the valve operator 64 being moved axially by the interface member 60 of the actuation assembly 46 results in rotation of the valve member 20 around the rotation axis 24 from the closed position to the open position. As the valve member 20 rotates around the rotation axis 24, the valve operator 64 moves transversely relative to the drive recess 100. The open side of the drive recess 100 receives the head 90 of the valve operator 64 during this transverse movement. The longitudinal surface 93 of the head 90 moves temporarily out of contact with the elongate surface 99 of the drive recess 100 whilst the second operation surface 91b of the head 90 and the second end surface 101b of the drive recess 100 maintain sliding contact. The rectilinear form of the drive recess 100 and the head 90 provides a substantial contact surface area for distributing loads transferred between the actuation assembly 46 and the valve member 20 during rotation of the valve member 20, thereby reducing stress concentrations. The alignment of the rotation axis 24 of the valve member 20 and a central plane of the interface member 60 is maintained by the guide assembly 52.

With continued reference to Figure 9C, as the valve member 20 rotates, the second stop surface 84b moves out of contact with the support surface 103 and the first stop surface 84a moves into contact with the support surface 103.

As can be seen in Figure 9D, once the first stop surface 84a abuts the support surface 103 continued rotation of the valve member 20 is prevented by the interaction between the limit stop 82 and the stop recess 102. In this position, the longitudinal surface 93 of the head has returned to contacting the elongate surface 99 of the drive recess. The rail 97 is again trapped between the limit stop 82 and the valve operator 64. In preventing over rotation of the valve member 20, forces are transferred between the limit stop 82 and the rail 97. These forces are balanced by opposing forces transferred between the valve operator 64 and the rail 97. The valve member 20 is now supported in the closed position with the throughbore 22 transverse to the flow path, as shown in Figure 9D.