The present invention relates to a butterfly valve assembly for an engine arrangement, an exhaust gas conduit arrangement for an engine comprising the butterfly valve assembly, and to a valve member for a butterfly valve.

It is known in the art to use butterfly valve assemblies (e.g. comprising a valve housing and a valve member [which may be referred to as a flap valve]) in engine arrangements. The valve assemblies may take various forms in engine arrangements including, but not limited to, Exhaust Throttle Valves (ETV) and Exhaust Gas Recirculation (EGR) Valves. The functionality of such valve assemblies includes selectively increasing the back pressure of exhaust gas flow across the valve (e.g. for engine braking or to increase pumping work for thermal management).

Given the relatively high temperature environment in which such butterfly valve assemblies operate (e.g. around 900 degrees Kelvin), valve housings and valve members of butterfly valve assemblies may be liable to thermal distortion (e.g. expansion) in operation. Specifically, the constituent components of butterfly valve assemblies may be liable to different levels of thermal expansion (owing to the valve member and valve housing being made from different materials, having different associated coefficients of thermal expansion). Such thermal distortion risks the valve member becoming jammed within the valve housing, which risks the operation of the overall butterfly valve assembly. For example, in certain circumstances the valve member may not be able to follow (i.e. rotate to) a command position from a linked actuator. However, the need for maintaining a clearance between the valve member and the valve housing (to allow the valve member to rotate within the housing) must be balanced with the need to be able to near-completely seal across the valve member when the valve member is in a fully closed configuration. Furthermore, materials with comparatively greater thermal resistance are typically higher cost and more difficult to machine.

There exists a need to overcome one or more of the disadvantages associated with existing butterfly valves assemblies, whether mentioned in this document or otherwise. According to a first aspect of the invention there is provided a butterfly valve assembly for an engine arrangement, the butterfly valve assembly comprising: a valve housing defining at least part of a conduit; and a valve member disposed within the conduit and rotatable about an axis between an open configuration, in which fluid flow is permitted through the conduit across the valve member, and a closed configuration, in which the valve member seals the conduit; wherein the valve member is rotatable in a first direction from the open configuration to the closed configuration; and wherein the valve member comprises: a blocking surface which extends across the conduit, in the closed configuration, to seal the conduit; a secondary surface which generally opposes the blocking surface; and a peripheral surface which extends between the blocking surface and the secondary surface and defines a thickness of the valve member; wherein a first end portion of the peripheral surface extends around the axis at a first end of the valve member; wherein a clearance is defined between the conduit and a vertex of the first end portion closest to the conduit; and wherein the clearance is at a minimum, as the valve member pivots from the open configuration to the closed configuration, when the valve member is in the closed configuration.

The butterfly valve assembly may specifically be for use as an exhaust throttle valve (ETV) or an exhaust gas recirculation valve (EGR valve). The engine arrangement may comprise a turbomachine such as a turbocharger.

The valve housing preferably surrounds the valve member and defines one or more location features configured to receive a shaft. The shaft preferably also extends through the valve member and defines the axis. The conduit preferably extends at least as far so as to fully surround the valve member, in all directions, when the valve member is in both the fully open and fully closed configurations.

The valve member may otherwise be described as a valve body or a flap valve. When the valve member is in an open configuration (i.e. a fully open configuration) a minimum cross-sectional area of the conduit is blocked by the valve member. Put another way, in a fully opened configuration the valve member does the minimum amount of blocking, or sealing, of fluid in the conduit. In the closed configuration (i.e. fully closed configuration) the valve member provides a maximum blocking effect (e.g. a highest back pressure). However, the valve member may not hermetically seal the conduit even in the closed configuration, owing to the need for at least some clearance for the valve member to be pivoted within the conduit. That said, in some embodiments the valve member may hermetically seal the conduit when in the fully closed configuration.

The valve member being rotatable in the first direction may otherwise be described as the valve member being rotatable in a closing direction. When the valve member is in the fully closed configuration, the valve member may not be provided normal to a direction of flow through the conduit. Instead, the valve member may be provided at a relative angle within the conduit. This may advantageously improve the operation of the valve by providing more clearance for the valve to rotate within the conduit. This may be facilitated by providing a bevelled edge, preferably at a leading edge of the valve member.

The blocking surface may be described as a first surface (e.g. a first major surface, or major face) of the valve member. The secondary surface may be described as a second surface (e.g. a second major surface, or major face) of the valve member.

The first end portion of the peripheral surface may be flat. The first end portion of the peripheral surface may otherwise be described as an outermost surface of the valve member, excluding any possible integrated shaft. The first end portion of the peripheral surface may refer to either an upper or a lower end portion (e.g. at a side of the valve member proximate, or distal, the actuator). The first end portion may define a bore through which a shaft is received, the combination of the shaft and bore defining the axis. The first end of the valve member may be either an upper or lower end of the valve member.

The clearance being defined between the conduit and a vertex may otherwise be described as a clearance specifically being defined between an internal surface of the conduit and the vertex. The vertex may be a comparatively sharp vertex (i.e. a corner) or may be a point on an edge (e.g. a point on a fillet). The vertex of the first end portion closest to the conduit is intended to refer to the vertex of the first end portion which is closest to the conduit as the valve member moves towards a fully closed configuration. The vertex of the first end portion closest to the conduit may be referred to as a first vertex, or a leading vertex. The clearance being at a minimum, as the valve member pivots from the open to the closed configuration, when the valve member is in the closed configuration, is intended to mean that of all points where the valve member moves from a fully open to a fully closed configuration, the clearance is only at a minimum when the valve member reaches the fully closed configuration. Described another way, a minimum clearance is not reached before the valve member is provided in a fully closed configuration. For example, a point of minimum clearance does not exist when the valve member is at an 80% closed configuration (i.e. a partially closed configuration). The axial position of the vertex may be a plane in which the first end portion lies. The clearance may be defined in a plane normal to the axis at the axial position of the vertex. A direction of the clearance (e.g. if a line were drawn between the vertex and the portion of the conduit closest to the vertex) may vary with rotation of the valve member. Similarly, a point on the conduit, closest to the vertex, may vary with rotation of the valve member.

Advantageously, a butterfly valve assembly according to the invention only defines a point of minimum clearance, at a first end portion of the valve member, when the valve member is in the closed configuration. The minimum clearance is thus only reached when the valve member is in the fully closed configuration. This alleviates issues associated with the sticking of the valve member within the valve housing or conduit in a partially closed configuration, particularly due to significant thermal transients in operation. For example, in some arrangements a minimum clearance may be defined as the valve member moves partway from a fully open to a fully closed configuration. Rotation of the valve member may thus be impeded by the valve member, specifically the vertex thereof, fouling on a closest portion of the conduit. The fouling may be the result of the significant thermal transients leading to relative thermal expansion between the conduit and the valve member.

The invention provides advantageous alternatives to using materials which have a greater heat resistance (which are more costly and more difficult to machine) and reducing a height of the valve member (which, whilst increasing the clearance, increases leakage at all operational points of the valve assembly). The first end portion of the peripheral surface may be defined by at least first and second recesses.

Advantageously, the first and second recesses reduce the risk of the valve member, specifically the first end portion thereof, fouling on the closest portions of the conduit as the valve member moves from a fully open to a fully closed configuration.

The presence of the first and second recesses may effectively define the first end portion as a projecting feature relative to those recesses. The first and second recesses preferably occupy different quadrants of the first end portion of the valve member. In preferred arrangements the first and second recesses extend beyond the fourth and second quadrants of the first end portion respectively, the second and fourth quadrants otherwise being described as closing quadrants which, as the valve member moves towards the fully closed configuration, are first provided proximate the conduit. The first and second recesses may be substantially identical to one another in volume. The first and second recesses may be provided in a rotationally symmetric arrangement about the axis.

The first and second recesses may be disposed across the axis from one another.

The first and second recesses being disposed across the axis from one another may otherwise be described as the first and second recesses provided in different quadrants. The first and second recesses are preferably provided in different, diagonally opposing quadrants. When the valve member is viewed from above or below, such that a vertical plane extends through the axis and a horizontal plane, or mid-plane, extends normal to the vertical plane also through the axis, the first and second recesses are preferably provided on different left and right hand sides of the vertical plane. Described another way, the first and second recesses are preferably provided on different sides of the vertical plane. The first recess is preferably provided on a right hand side of the valve member. The second recess is preferably provided on a left hand side of the valve member.

Advantageously, by providing the first and second recesses across the axis from one another, the risk of the valve member sticking as the valve rotates in either direction is reduced or eliminated. Furthermore, providing the first and second recesses in this manner means the mass of the valve member is more evenly distributed about the axis, providing for a smoother rotation in operation. More balanced aerodynamic loading is also realised in use.

The first recess may extend to the blocking surface, and the second recess may extend to the secondary surface.

The first recess extending to the blocking surface may otherwise be described as the first recess extending from the blocking surface. Described another way, the first recess extends from a front of the valve member. The second recess extending to the secondary surface may otherwise be described as the second recess extending from the secondary surface. The second recess may otherwise be described as being provided at a rear of the valve member.

This arrangement has been found to be particularly advantageous where, when the valve member is in the fully closed configuration, when the valve member is viewed from above, in the fully closed configuration the valve member is provided at a slight anti-clockwise rotation relative to the blocking face extending entirely normal to the conduit.

A mid-plane of the valve member may be defined through the peripheral surface between the blocking and secondary surfaces; and wherein the first recess extends at least from the blocking surface to the midplane; and wherein the second recess extends at least from the secondary surface to the mid-plane.

The mid-plane of the valve member may otherwise be described as a horizontal plane of the valve member when the valve member is viewed either from above or below. The first recess extending at least from the blocking surface to the mid-plane may otherwise be described as the first recess extending at least halfway across the thickness of the valve member. Similarly, the second recess extending at least from the secondary surface to the mid-plane may otherwise be described as the second recess also extending at least halfway across the thickness of the valve member. The first and second recesses may be described as extending in opposite directions given that they extend from different (i.e. opposing) sides, or major faces, of the valve member.

Advantageously, the first and second recesses extending as set out above has been found to provide more than ample clearance for the valve member to be able to rotate during high temperature operation. The recesses extending to this extent also saves on material usage and therefore reduces the mass of the valve member and associated operational energy requirements.

The first recess may extend at least from the blocking surface past the mid-plane; and wherein the second recess extends at least from the secondary surface past the mid-plane.

The first end portion may be further defined by third and fourth recesses.

The third and fourth recesses may be comparatively smaller in volume compared to the first and second recesses. Advantageously, the incorporation of third and fourth recesses provides material and weight saving benefits for the valve member.

The first and third recesses may be disposed on one side of the first end portion, and wherein the second and fourth recesses may be disposed on the other side of the first end portion.

The sides of the end portion referred to here indicate which side of a vertical plane, extending through the axis and normal to a mid-plane when the valve member is viewed from above or below, the recesses are provided. Described another away, when the valve member is viewed from above, the first and third recesses may be disposed on a right hand side, and the second and fourth recesses may be disposed on a left hand side. The combination of the first and third recesses may define at least part of the second projection. The combination of the second and fourth recesses may define at least part of the first projection. The combination of each of the first, second, third and fourth recess may define an entirety of the first end portion.

A bore may extend through the valve member along the axis. The bore may be configured to receive a shaft therethrough. The centre point of the bore may define the axis of rotation about which the valve member rotates.

Advantageously, providing a bore through the valve member means that the valve member can readily be installed in place within the valve housing, specifically the conduit thereof. A shaft can then be inserted therethrough.

The bore may be disposed in a thickened portion of the valve member.

The thickened portion of the valve member, as suggested by the name, refers to a region of the valve member in which a separation between the blocking and secondary surfaces is greatest. The thickened portion may be generally rectangular when viewed in cross section normal to the axis. The thickened portion of the valve member is thickened to provide a greater cross sectional area of material to be able to receive the shaft.

A contributor of the issues faced by baseline valve members is that the presence of the thickened portion effectively increases the distance between the axis and a radially outermost point of the end portion of the valve member. The geometry described herein can be considered to mitigate any clearance issues which may otherwise result from the incorporation of a thickened portion of the valve member.

A lip of the first end portion may extend around the bore.

The lip refers to a comparatively low thickness region of material which extends around the bore. The lip may be said to border the bore and extend circumferentially therearound.

The lip may have a thickness of at least around 1 mm (e.g. around 1.5 mm). Advantageously, the presence of the lip, which extends around the bore, reduces the risk of fluids leaking around the valve member proximate the shaft. The presence of the lip therefore improves the sealing around the shaft. The first end portion may be further defined by first and second projections which extend from the lip.

The first and second projections may otherwise be referred to as first and second arms. The first and second projections extending from the lip is intended to encompass the first and second projections being integral with the lip. Described another way, the combination of the first and second projections and the lip may collectively define an entirety of the first end portion.

Advantageously, the presence of the first and second projections, in cooperation with the lip, mean that the first end portion provides an ample sealing across the conduit (when the valve member is in the fully closed configuration) whilst the risk of the valve member sticking within the conduit is reduced.

The first and second projections, and the lip portion, may define a web of material, the web of material defining the first end portion.

The web of material defining the first end portion is intended to encompass the web of material defining an entirety of the first end portion. Described another way, the first end portion is the web of material. The web of material is intended to refer to a geometric arrangement of material which has a comparatively narrow cross section when viewed normal to the axis. Described another way, an associated thickness of all the material defining the web of material, normal to the axis, is comparatively low. For example, the thickness of the material may be at least around 1 mm (e.g. around 1.5 mm).

The first projection may be disposed on a first side of the first end portion, and the second projection may be disposed on the other side of the first end portion.

The first projection being disposed on the first side of the first end portion may otherwise be described as the first end portion being provided on a left hand side of a vertical plane through the valve member when the valve member is viewed from an upper or lower end. The second projection being disposed on the other side of the first end portion may otherwise be described as the second projection being disposed on an opposite side of the vertical plane. The first projection may be defined by the first and third recesses, and the second projection may be defined by the second and fourth recesses.

A second end portion of the peripheral surface, corresponding to the first end portion, may be disposed at an opposing second end of the valve member.

A second end portion of the peripheral surface corresponding with the first end portion is intended to mean that a mirrored arrangement of end portion is provided at the opposing end of the valve member. In preferred embodiments the first end portion corresponds to the lower end of the valve member. In preferred embodiments the valve member has a plane of symmetry when viewed normal to the blocking face about a plane which extends horizontally through a mid-point of the valve member (save for rivet bores).

Advantageously, by providing a corresponding end portion at the other end of the valve member, the risk of the valve member becoming stuck with the conduit is further reduced.

The clearance may be at least around 0.3 mm when the valve member is at an 80% closed position.

Advantageously, by providing a clearance of at least around 0.3 mm when the valve is at an 80% closed position, a point of minimum clearance which may otherwise have been present is reduced to an acceptable level. The risk of the valve member sticking within the conduit is thus reduced.

The mid-plane and a second plane, normal to the mid-plane and the axis, may define four quadrants of the valve member.

The second plane, normal to the mid-plane and the axis, may otherwise be described as a vertical plane. Any projecting feature(s) of the first end portion may be located outside of two diagonally opposed quadrants which are proximate the conduit when the valve member is in the closed configuration.

Projecting features is intended to refer to any feature which excludes a lip. For example, first and second projections are examples of projecting features. Projecting features may refer to any feature which projects from the axis by greater extent than an outer edge of the lip.

The projecting features being located outside of two diagonally opposed quadrants proximate the conduit when the valve member is in the closed configuration may otherwise be described as the projecting features being located outside of the two leading quadrants. The diagonally opposed quadrants proximate the conduit when the valve member is in the closed configuration is intended to refer to the two quadrants which are first brought into closest proximity to the conduit as the valve member is moved towards a fully closed configuration.

Advantageously, by excluding any projecting features of the first end portion from the two leading quadrants, a greater clearance is provided at the first end portion when the valve member approaches a fully closed configuration.

The vertex may be located in one of two diagonally opposed quadrants which are distal the conduit when the valve member is in the closed configuration.

The two diagonally opposed quadrants distal the conduit when the valve member is in the closed configuration may otherwise be described as trailing quadrants. Described another way, as the valve member moves towards the closed configuration these are the two diagonally opposed quadrants which are generally provided furthest away from the conduit.

Advantageously, by locating the vertex in one of these trailing conduits, a greater clearance is provided as the valve member is moved towards the closed configuration. Described another way, a clearance is provided at, or in, the leading quadrants which may otherwise have not been present owing to the vertex. The butterfly valve assembly may be an exhaust throttle valve (ETV) or exhaust gas recirculation (EGR) valve.

An exhaust throttle valve is used in an engine arrangement to generate back pressure for engine braking or thermal management (i.e. increasing the temperature of an exhaust aftertreatment device) by way of increased pumping work.

An exhaust gas recirculation valve (EGR valve) is located in an exhaust conduit and used to selectively recirculate exhaust gas back into an intake manifold. An EGR valve is used to control Nitrogen Oxide (NO _X ) emissions. Described another way, the EGR valve can be considered to be a valve which provides selective fluid communication between an exhaust manifold and intake manifold in an engine.

Both ETV and EGR valves operate in high temperature environments, and so the butterfly valve assembly according to the invention is particularly useful when used as an ETV or EGR valve.

According to a second aspect of the invention there is provided an exhaust gas conduit arrangement for an engine, the exhaust gas conduit arrangement comprising: an exhaust gas conduit in fluid communication with the engine; and the butterfly valve assembly according to the first aspect of the invention; wherein the butterfly valve assembly is provided in fluid communication with the exhaust gas conduit; and wherein the valve member is operable to selectively seal the exhaust gas conduit.

The butterfly valve assembly can be an EGR valve or an ETV. The engine may be an internal combustion engine such as a spark ignition or compression ignition engine. The engine may be a hybrid engine comprising a combination of an internal combustion engine and an electric motor.

Advantageously, the valve member is operable to selectively seal the exhaust gas conduit to increase the back pressure in the exhaust gas conduit. This may be used to provide for engine braking functionality and/or increase pumping work for thermal management reasons (i.e. to bring an exhaust aftertreatment device to an operating temperature).

According to a third aspect of the invention there is provided a valve member for a butterfly valve assembly, the valve member comprising: a blocking surface configured to impede a fluid flow; a secondary surface which generally opposes the blocking surface; a peripheral surface which extends between the blocking surface and the secondary surface and defines a thickness of the valve member; and an axis of rotation which extends through the valve member; wherein a first end portion of the peripheral surface extends around the axis of rotation, the first end portion being defined by at least first and second recesses; wherein a mid-plane of the valve member is defined through the peripheral surface between the blocking and secondary surfaces; and wherein the first recess extends at least from the blocking surface past the midplane, and the second recess extends at least from the secondary surface past the mid-plane.

In preferred embodiments, the first and second recesses extend through leading quadrants of the valve member (i.e. the quadrants which are first provided in closest proximity to the conduit when the valve member moves towards the closed configuration).

Advantageously, the valve member having the aforementioned geometry is less likely to stick within a conduit owing to relative thermal expansion between the valve member and the surrounding conduit.

According to a fourth aspect of the invention there is provided a valve member for a butterfly valve assembly, the valve member comprising: a blocking surface configured to impede a fluid flow; a secondary surface which generally opposes the blocking surface; a peripheral surface which extends between the blocking surface and the secondary surface and defines a thickness of the valve member; and an axis of rotation which extends through the valve member; wherein a first end portion of the peripheral surface extends around the axis of rotation, the first end portion defined by a web of material.

In preferred embodiments, the first and second recesses extend through leading quadrants of the valve member (i.e. the quadrants which are first provided in closest proximity to the conduit when the valve member moves towards the closed configuration).

Advantageously, the valve member having the aforementioned geometry is less likely to stick within a conduit owing to relative thermal expansion between the valve member and the surrounding conduit.

The web of material defining the first end portion is intended to encompass the web of material defining an entirety of the first end portion. Described another way, the first end portion is the web of material. The web of material is intended to refer to a geometric arrangement of material which has a comparatively narrow cross section when viewed normal to the axis. Described another way, an associated thickness of all the material defining the web of material, and applying normal to the axis, is comparatively low. For example, the thickness of the material may be at least around 1 mm (e.g. around 1.5 mm).

The optional and/or preferred features of each aspect of the invention as set out herein are also applicable to any other aspects of the invention where appropriate.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a butterfly valve assembly according to an embodiment of the invention;

Figure 2 is a front view of the butterfly valve assembly of Figure 1;

Figure 3 is a front view of a valve member of the butterfly valve assembly of Figure 1 shown in isolation;

Figure 4 is perspective view of the valve member of Figure 3;

Figures 5 and 6 are end-on views of the valve member of Figures 3 & 4;

Figure 7 is a perspective view of a baseline valve member showing an end portion of the baseline valve member; Figure 8 is a perspective view of an end of the valve member shown in Figures 3 to 6;

Figure 9 is a front view of part of the butterfly valve assembly shown in Figures 1 and 2;

Figure 10 shows the first end portion of the baseline valve member, of Figure 7, in-situ in a butterfly valve assembly according to the section view indicated in Figure 9;

Figure 11 shows the first end portion of the valve member of Figures 3 to 6 and 8, in- situ in a butterfly valve assembly according to the section view indicated in Figure 9;

Figure 12 is a magnified front view of the arrangement shown in Figure 10 with the baseline valve member at a 100% closed position;

Figure 13 is a magnified front view of the embodiment shown in Figure 11 with the valve member at a 100% closed position;

Figure 14 is a magnified front view of the arrangement shown in Figure 10 with the baseline valve member at an 80% closed position;

Figure 15 is a magnified front view of the embodiment shown in Figure 11 with the valve member at an 80% closed position;

Figures 16a-d show the arrangement of Figure 10 as the baseline valve member moves from a 70% to a 100% closed configuration;

Figures 17a-d show the embodiment of Figure 11 as the valve member moves from a 70% to a 100% closed configuration;

Figure 18 is a graph showing how a minimum clearance between the valve member and the conduit varies with the rotational position of the valve members shown in Figures 7 and 8 respectively; and

Figure 19 is a table of values plotted in Figure 18.

Figure 1 is a perspective view of a butterfly valve assembly 2 according to an embodiment of the invention.

The butterfly valve assembly 2 comprises a valve housing 4 and a valve member 6. The valve housing 4 defines at least part of a conduit 8 across which the valve member 6 extends. In the illustrated embodiment the conduit 8 extends from an upstream end 10 to a downstream end 12. In use, fluid (e.g. exhaust gas) flows through the conduit 8 (unless prevented by the valve member 6). As will be appreciated from subsequent Figures, the valve member 6 is disposed within the conduit 8 and is rotatable about an axis between an open (i.e. fully open) and a closed (i.e. fully closed) configuration. In the open configuration, fluid flow through the conduit 8 (i.e. from the upstream end 10 to the downstream end 12, across the valve member 6) is permitted. In the closed configuration, the valve member 6 extends across the conduit 8 so as to substantially block fluid flow across the conduit 8. Described another way, in the closed configuration the valve member 6 substantially seals the conduit 8. For completeness, the position of the valve member 6 in both Figures 1 and 2 is a configuration part-way between the open and closed configurations, with the valve member 6 being in an 80% closed configuration. For completeness, the 80% closed configuration refers to the proportion of the ‘full’ angular travel of the valve member 6 which the valve member 6 is provided at. For example, in a fully open configuration the valve member 6 (specifically a mid-plane 66, as shown in Figure 5) is provided at ~0° to a vertical plane (for the butterfly valve assembly 2 orientation shown in Figure 2) which extends through a central axis of the conduit 8. Described another way, in the fully open configuration the mid-plane 66 of the valve member 6 extends along the conduit 8. In the fully closed configuration, the valve member 6 (again, specifically the mid-plane 66) is provided at 74.2° (in the illustrated embodiment) relative to the aforementioned vertical plane which extends through the central axis of the conduit 8. The 74.2° rotational offset may be in either rotational direction, depending upon the valve member 6 geometry (e.g. depending upon outer edges 82, 84 and angles 88 as shown in Figure 5). The valve member 6 may contact the internal surface of the conduit 8 in the fully closed configuration. The 80% closed configuration may otherwise be described as a mid-plane 66 of the valve member 6 being rotationally offset, from a vertical plane through the conduit 8, by around 59.4° in the illustrated embodiment (e.g. 80% of the ‘full’ 74.2° rotational offset of the fully closed configuration).

Figures 1 and 2 also show part of a blocking surface 14 of the valve member 6. On a generally opposing side of the blocking surface 14 a secondary surface is defined, although the secondary surface is not visible in Figures 1 or 2.

The valve member 6 is shown attached to, or mounted to, a shaft (not visible) by rivets 18a, b. Heads of the rivets 18a, b are provided proximate the blocking surface 14 in the illustrated embodiment. However, this may not be the case in other embodiments (e.g. rivet heads may be provided proximate the secondary surface in other embodiments). Furthermore, it will be appreciated that a number of other ways of securing the valve member 6 to the shaft may otherwise be employed (e.g. laser welding). Other ways of securing the valve member 6 to the shaft include the use of splines, a threaded engagement and/or a press-fit.

Figures 1 and 2 also a number of other components which form part of the butterfly valve assembly 2. An actuator 20 is provided in torque communication with the valve member 6 to rotate the valve member 6. The illustrated actuator 20 is an electric actuator but in other embodiments the actuator may otherwise be a pneumatic or hydraulic actuator. The actuator 20 is in torque communication with the valve member 6 via an intermediate drive plate 30 and a spring 32.

The actuator 20 is coupled to the valve housing 4 via an actuator bracket 22. The actuator bracket 22 is fastened to the valve housing 4 by a plurality of fastener 74a-d. Also attached to the actuator bracket 22 is a heat shield 26 which serves to protect the actuator 20 from high surrounding temperatures. The heat shield 26 is coupled to the actuator bracket 22 by a plurality of fasteners 28a-d.

A particular focus of the present invention is the geometry of first and second end portions 34, 36 of the valve member 6. In the illustrated embodiment the first and second end portions 34, 36 correspond to lower and upper faces of the valve member 6 respectively. Described another way, in the illustrated embodiment the first and second end portions 34, 36 refer to the outermost surfaces of the valve member 6 about the axis which the valve rotates and which are distal, and proximate, the actuator 20 respectively. For reasons which will become clear later in this document, in use the first and second end portions 34, 36 of the valve member 6 may undesirably contact (e.g. foul on) the surrounding valve housing 4, specifically the conduit 8 thereof. This is worsened by thermal expansion of the valve member 6 and/or the valve housing 4 in operation, owing to the high temperature environment in which the butterfly valve assembly 2 operates. One aspect of the present invention overcomes this issue by providing a modified geometry at one or both of the first and second end portions 34, 36 which provides increased clearance at otherwise problematic ‘pinch points’ but not to the detriment of the sealing capability of the valve member 6.

Upper and lower faces of the valve member 6 may otherwise be described as being actuator bush and bottom bush sides respectively. The valve member 6 is preferably manufactured from austenitic stainless steel. The valve housing 4 is preferably manufactured from cast iron. The valve member 6 thus expands more quickly, due to higher temperatures, owing to cast iron having a lower coefficient of thermal expansion.

Turning to Figure 3, an effective front view of the valve member 6 is provided. The front view of Figure 3 is taken normal to the blocking surface 14 of the valve member 6.

As discussed in connection with Figures 1 and 2, the valve member 6 comprises the blocking surface 14 and the opposing secondary surface 16 (the secondary surface not being visible in Figure 3, but just visible in Figure 4). A peripheral surface 38 extends between the blocking surface 14 and the secondary surface to define an effective thickness of the valve member 6. This is shown more clearly in Figures 4 and 5. As shown in Figure 3 the peripheral surface 38 defines part of a bevelled edge when viewed normal to the blocking surface 14. Again, this is also shown in Figure 5.

Returning to Figure 3, a thickened portion 40 of the valve member 6 extends across part of the blocking surface 14. The thickened portion 40 is also shown in Figure 4. At the thickened portion 40, an extent, or thickness, of the peripheral surface 30 is effectively increased to provide space for the valve member 6 to accommodate a shaft (not shown in Figure 3) therethrough.

Two rivet bores 42a, 42b extend through the thickened portion 40 of the valve member 6 through an entirety of the valve member 6. As suggested by the name, the rivet bores 42a, 42b receive the rivets 18a, 18b (shown in Figure 2) to couple the valve member 6 to the shaft (not shown in Figure 3).

An axis 44 is also schematically indicated in Figure 3. The axis 44 is the axis about which the valve member 6 rotates in use.

Also labelled in Figure 3 are first and second end portions 34, 36 of the valve member 6. Each of the first and second end portions 34, 36 extends around the axis 44 at a respective upper or lower end 46, 48 of the valve member 6. The first and second end portions 34, 36 may be described as defining outermost geometries of the valve member 6 at uppermost and lowermost ends of the valve member 6 respectively. As shown in Figure 3, the valve member 6 is generally symmetrical about a plane of symmetry 49 save for a first (upper) rivet bore 42a being slightly closer to the plane 49 than a second (lower) rivet bore 42b. Described another way, in the absence of the rivet bores 42a, 42b, the valve member 6 is symmetrical about the plane of symmetry 49.

Turning to Figure 4, a perspective view of the valve member 6 is provided generally from an upper end 46 of the valve member 6 and from a blocking surface 14 side. Many of the features described in connection with Figure 3 are also shown in Figure 4 and the description will therefore not be repeated for brevity.

Figure 4 shows the thickened nature of the thickened portion 40 in comparison to a thickness of the valve member 6 across the rest of the blocking surface 14. Furthermore, Figure 4 also shows a bore 50 which extends through an entire axial extent of the valve member 6 and which is configured to receive a shaft in use. The axis 44 may therefore be described as being defined by the bore 50. The bore 50 is a throughbore in the illustrated embodiment.

More features of the first end portion 34 are also visible in Figure 4. Although these will be described in greater detail in connection with Figures 5 and 6, as previously mentioned the first end portion 34 is an outermost surface of the valve member 6 at the upper end 46 of the valve member 6. In the illustrated embodiment the first end portion 34 is flat and extends normal to the axis 44. The first end portion 34 is defined by a web of material comprising first and second projections 52, 54 and a lip 56.

The first end portion 34 may be described as being defined by four recesses: first to fourth recesses 58, 60, 62, 64. The first recess 58 extends from the blocking surface 14 past a mid-plane (which will be described in connection with Figure 5, labelled 66 in Figure 5). Returning to Figure 4, the second recess 60 extends from the secondary surface 16 past the mid-plane. The first and second recesses 58, 60 are located in diagonally opposing corners, or quadrants, about the axis 44 (as will be described in more detail in connection with Figure 5, later). In the illustrated embodiment the first and second recesses 58, 60 are substantially identical to one another, but are rotated by 180° about the axis 44 from one another. The first and second recesses 58, 60 may be described as corresponding recesses. The first and second recesses 58, 60 are the larger of the four recesses in the illustrated embodiment.

The third recess 62 extends from the secondary surface 16 but does not extend to, or past, the mid-plane. Both second and third recesses 60, 62 thus extend from the secondary surface 16 side of the valve member 6 (i.e. extend from the same major face of the valve member 6). The fourth recess 64 extends from the blocking surface 14 but does not extend to, or past, the mid-plane. Like the first and second recesses 58, 60, the third and fourth recesses 62, 64 are substantially identical to one another, but are rotated by 180° about the axis 44 from one another. The third and fourth recesses 62, 64 may be described as corresponding recesses. The third and fourth recesses 62, 64 are the smaller of the four recesses in the illustrated embodiment.

The combination of the first to fourth recesses 58, 60, 62, 64 define the first end portion 34 which, in the illustrated embodiment, takes the form of a web of material.

Turning now to Figure 5, a plan view of the valve member 6 in isolation is provided. In Figure 5 the illustration is shown from an upper end of the valve member (i.e. labelled 46 in Figure 4).

In Figure 5 a horizontal mid-plane 66 is also schematically indicated. The horizontal mid-plane 66 extends through the axis 44 and generally across a mid-point of the thickness defined by the peripheral surface 38 of the valve member 6. A second plane 68, which may be referred to as a vertically extending, or vertical, plane, which also extends through the axis 44 extends normal to the mid-plane 66. A combination of the mid-plane 66 and secondary plane 68 thus define four quadrants: a first quadrant 70, a second quadrant 72, a third quadrant 74 and a fourth quadrant 76. The first quadrant 70 is taken to be the lower left hand quadrant as shown in Figure 5, with the second to fourth quadrants 72, 74, 76 being arranged in a clockwise manner from the first quadrant 70.

The second and fourth quadrants 72, 76 may be referred to as leading quadrants in that these are the quadrants which are first located in closest proximity to the conduit when the valve member 6 moves towards a closed configuration. The first and third quadrants 70, 74 may be referred to as trailing quadrants in that these are the quadrants which are located distal the conduit when the valve member 6 moves towards a closed configuration. Described another way, the second and fourth quadrants 72, 76 are provided in proximity to the conduit before the first and third quadrants 70, 74 as the valve member 6 moves towards a closed configuration.

As described in connection with Figure 4, the first end portion 34 is the uppermost surface of the valve member 6. The first end portion 34 extends around the bore 50, and so axis 44, of the valve member 6. The first end portion 34 is defined by a combination of the lip 56, which directly extends around an entirety of the bore 50, and first and second projections 52, 54 which extend from the lip 56.

Figure 5 also illustrates the bevelled edge which extends around part of the valve member 6 as defined by the peripheral surface 38. In particular, at left and right hand sides 78, 80 of the illustrated valve member, it will be appreciated that outer edges 82, 84 are not parallel to the vertical plane 68. Instead, these edges extend at a relative angle (i.e. are inclined relative) to the vertical plane 68. For the left hand side 78 of the valve member 6, the outer edge 82 is shown extending at a relative angle 88 to a plane 90 which extends normal to the mid-plane 66 at the same position (i.e. at an outermost left hand edge of the valve member 6). The angle 88 is approximately 20° in the illustrated embodiment, which corresponds to the position of the valve member 6, about the axis 44, when the valve member 6 is in a fully closed configuration. A rotationally symmetric geometry is provided at the right hand side 80, although not labelled in Figure 5. A rotationally symmetric, or uniform, geometry is advantageous for reasons of improved fatigue performance. Furthermore, a rotationally symmetric geometry means that as the valve member 6 rotates, the clearance between the valve member 6 and the internal surface of the conduit 8 at either side of the secondary plane 68 is the same (e.g. on either side of the valve member 6). Specifically, the clearance between rotationally offset vertices of the end portion(s) (e.g. 94 and 98) and the internal surface of the conduit 8 is the same for a given rotational position of the valve member 6. Described another way, a geometric proximity of the valve member 6 to the conduit 8 is also rotationally symmetric. The entire valve member 6 may have a rotationally symmetric geometry, when viewed from above or below, in preferred embodiments. When the valve member 6 is in the closed configuration, edges 82, 84 align substantially parallel with a corresponding edge of the conduit which is sealed by the valve member 6. As such, from Figure 5 it will be appreciated that when the valve member 6 is in the fully closed configuration, the rotational position of the valve member 6 is actually slightly offset from that shown in Figure 5, by up to around 20° in an anti-clockwise direction about the axis 44.

Returning to describe details of the first end portion 34, an axial depth of each of the recesses 58, 60, 62, 64 is between around 1.2 mm and around 1.4 mm (e.g. around 1.3 mm) in the illustrated embodiment. In other embodiments the depth may be anywhere up to around 3 mm (e.g. from around 1 mm to around 2 mm thick). The depth is taken relative to the first end portion 34. A fillet extends around the first end portion 34, the fillet having a radius of around 0.6 mm. In other embodiments the fillet radius may be anywhere up to around 2 mm. One such point of the above-mentioned fillet is labelled 86 in Figure 5. However, as mentioned, this fillet generally extends continuously around the first end portion 34. See also Figure 4 for a perspective view which illustrates the exact position of the fillet. A radius of the lip contour 57 is around 5.25 mm in the illustrated embodiment. The radius 57 may be between around 2 mm and around 8 mm. A radius of the contour 59 is around 4 mm in the illustrated embodiment. The radius 59 may be between around 2 mm and around 10 mm. A minimum height of the projections 52, 54 labelled 55 is around 1.5 mm in the illustrated embodiment. The height 55 may be between around 1 mm and around 5 mm. The first and second projections 52, 54 are offset from the mid-plane 66 by around 1 mm at a closest point in the illustrated embodiment. They may be offset by between around 0.5 mm and around 3 mm.

Returning to Figure 5, as previously mentioned the first end portion 34 comprises first and second projections 52, 54. Beginning with the first projection 52, the first projection 52 comprises first and second vertices 92, 94. The vertices may otherwise be referred to as corners or outer points. The first and second vertices 92, 94 may respectively be referred to as leading and trailing vertices, or points. The leading and trailing vertices 92, 94 define two of the radially outermost points of the first end portion 34 relative to the axis 44. A first outer edge 96 extends between the leading and trailing vertices 92, 94. From Figure 5 it will be appreciated that the first outer edge 96 extends at an angle relative to the vertical plane 68. The first outer edge 94 is preferably parallel with the left edge 82 as shown at the left side 78 of the valve member 6. Described another way, the relative angular offset of the first outer edge 96 to the vertical plane 68 can also be considered to be defined by the angle 88. Advantageously, this reduces the effective flow area across the valve member 6 in the fully closed configuration by virtue of the trailing vertices 92, 100 (e.g. corresponding to a trailing edge of first outer edge 96 and a leading edge of second outer edge 102) being located closer to the secondary plane 68.

As shown in Figure 5, both the leading and trailing vertices 92, 94 are located outside of the second quadrant 72. The combination of the first projection 52 effectively being located outside of the second quadrant 72, along with the geometry of the first end portion 34 generally (e.g. the combination of the lip 56 and the first and second projections 52, 54) advantageously reduces the risk that any part of the first end portion 34 foul on the conduit as the valve member 6 swings through towards a fully closed configuration. Furthermore, the first end portion 34 geometry can readily be manufactured using a machining process (e.g. milling) which would be carried out to machine the lip 56 anyway for alignment of the valve member 6 within the conduit 8. An outer face may be milled first, for use as a datum. The recesses 58, 60, 62, 62 may then be milled subsequently.

Briefly describing features in connection with the second projection 54, the second projection 54 comprises third and fourth vertices 98, 100 (which may be referred to as leading and trailing vertices respectively) and a second outer edge 102 which extends therebetween.

For both first and second projections 52, 54 the leading and trailing vertices are so called because as the valve member 6 swings through towards a closed configuration from an open configuration, it is the leading vertices which are provided in closest proximity to a surrounding point on the conduit, in that plane, before the trailing edge. Described another way, as the valve member 6 is transitioned to the fully closed configuration, the trailing vertices are generally provided distal the conduit in that plane.

Briefly, Figure 6 is identical to Figure 5 but is shown with many of the annotations removed. Although not mentioned in connection with either Figures 5 or 6, a mirrored arrangement of end portion is provided at the second end portion at the other end of the valve, in a plane of symmetry labelled 49 in Figure 3. Described another way, preferably the same geometric arrangement is provided at both ends of the valve member 6. As noted above, the first (upper) rivet bore 42a is slightly closer to the plane 49 than a second (lower) rivet bore 42b, and the valve member 6 is therefore not entirely symmetrical about plane 49.

Turning to Figure 7, a perspective view of part of a baseline valve member 200 falling outside of the scope of the present claims is provided. Baseline valve member 200 shares some features in common with the valve member 6 previously described, and for brevity these features will not be described in detail again here. However, in brief, the baseline valve member 200 comprises a blocking face 202 with an opposing secondary surface 204. A peripheral surface 206 extends between the blocking and secondary surfaces 202, 204 respectively. Defined at an upper end of the valve member 200 is a first end portion 208. The first end portion 208 is also a flat surface which defines an uppermost end surface of the valve member 200.

Defined in the first end portion 208 is a bore 210 which extends through an extent of the valve member 200. The first end portion 208 is defined by the first to fourth recesses 212, 214, 216, 218 which are generally located proximate each corner of the first end portion 208. By even briefly comparing Figures 7 and 8 it will be appreciated that, in contrast to the first end portion 34 of the valve member 6, the first end portion 208 has a comparatively larger surface area which also occupies each of four quadrants about an axis of rotation. Unlike the first end portion 34, the end portion 208 of the baseline valve member 200 incorporates material, beyond that of a lip extending around the bore, in each of four quadrants. For completeness, it will be recalled that the four quadrants are labelled 70, 72, 74 and 76 in Figure 5.

Returning to Figure 7, the first end portion 208 generally takes the form of a parallelogram which fully surrounds the bore 210.

Turning to Figure 8, briefly, Figure 8 is a perspective view of an upper end of the valve member 6 showing the first end portion 34. When compared to the baseline valve member 200 it will be appreciated that the first end portion 34 of the valve member 6 has a comparatively smaller surface area and, in particular, save for the lip 56, no material of the first end portion 34 extends into the second and fourth quadrants 72, 76 as labelled in Figure 5. Described another way, the first and second projections 52, 54 of the first end portion 34 are located outside of the quadrants located most closely to surrounding surfaces of the conduit as the valve member 6 moves toward the fully closed configuration.

Figure 9 is a front view of part of the butterfly valve assembly 2 shown in Figures 1 and 2. Figure 9 is taken from the upstream end 10 of the conduit 8, and the valve member 6 is also visible. Part of a shaft 104, which is received through the bore of the valve member 6, about which the valve member 6 rotates, is also visible in Figure 9. Section line 106 is also schematically indicated in Figure 9 and indicates the views about which the Figures 10 and 11 geometries are taken.

Figures 10 and 11 show the section view labelled 106 in Figure 9 corresponding to the baseline valve member 200 of Figure 7 and the valve member 6 of Figure 8 respectively. Commonly labelled on each of Figures 10 and 11 are the axis of rotation 44, the shaft 104 passing through a respective bore and the conduit 8 which is selectively sealed by the valve member. Figures 10 and 11 both show respective valve members at an 80% closed configuration. That is to say, the valve members are not shown in a fully closed configuration. The views of Figures 10 and 11 are both taken in planes which correspond to an axial position of the various vertices of the end portions, and particularly a plane which corresponds to an axial position of the vertex which defines the minimum clearance with the conduit 8.

In both Figures 10 and 11 fluid moves from a left hand side to a right hand side when the valve member is in an open configuration. The blocking surfaces are therefore the faces generally facing the left hand side, and the secondary surfaces are generally those which are facing the right hand side. However, it will be appreciated that the effective flow area across the valve member 6 is the same irrespective of which direction the fluid moves in. As such, fluid could equally move from the right hand side to the left hand side of Figures 10 and 11 when the valve member is in the open configuration. Described another way, the blocking surface could be located on either side of the valve member. A sealing effect is realised on both sides of the valve member (e.g. across the valve member generally). Beginning with Figure 10, the first end portion 208 of the baseline valve member 200 is illustrated with the shaft 104 extending through the baseline valve member 200. A clearance 220 is schematically illustrated in Figure 10. The clearance 220 is indicative of the distance between a first, or leading, vertex 222 of the first end portion 208 and a point 224 on the conduit 8, specifically an internal surface thereof, closest to the first vertex 222 at that position (and in that vertical plane, e.g. normal to the first end portion 208). The inventors have identified that when the baseline valve member 200 is in the 80% closed configuration as shown in Figure 10, the clearance 220 is a minimum clearance throughout the entirety of the baseline valve member 200 travel. Described another way, as the valve member 200 pivots from a fully open configuration to a fully closed configuration, the clearance 220 is the minimum distance between any point on the first end portion 208 and a corresponding point on the conduit 8. It has been identified that this minimum clearance 220, which is around 0.2 mm in the illustrated arrangement, is sufficiently low that, in use, relative thermal expansion between the conduit 8 and the valve member 200 can lead to the first vertex 222 of the baseline valve member 200 fouling on the conduit 8. It will be appreciated that this, in turn, can result in sticking of the overall baseline valve member 200 within the conduit 8 resulting in failure of the butterfly valve assembly. This is particularly problematic during heavy thermal transients. For example, where the butterfly valve assembly is used as an exhaust throttle valve (ETV), instances of hot shutdown (where the engine is turned off but the surrounding temperatures continue to increase as the flow of coolant stops) and when the engine transitions from a firing mode to a braking mode are circumstances where heavy thermal transients may be observed.

Although not illustrated in detail in Figure 10, it will be appreciated that a like clearance exists between a third vertex 230 (i.e. another leading vertex) and a corresponding point of the conduit 8.

For completeness, a clearance 226 exists between a second, or trailing, vertex 228 of the first end portion 208 and a corresponding point on the conduit 8. It will be appreciated that the clearance 226 is greater than the clearance 224. As such, it is the clearance 224 that is indicative of the ‘pinch point’, or minimum clearance, and it is therefore the first vertex (otherwise referred to as a leading vertex) 222 which is responsible for, or drives, the minimum clearance across the rotation of the baseline valve member 200 (and not the second, or trailing, vertex 228).

Turning to Figure 11 , the valve member 6, specifically the first end portion 34 thereof, is shown.

For completeness, it is noted that in the preceding Figures the first end portion has been indicated to be located at an upper end of the valve member 6. In contrast, Figure 11, as indicated by the annotation 106 in Figure 9, corresponds to a lower end of the valve member 6. Given that in the illustrated embodiment both ends of the valve member 6 incorporate corresponding end portions (i.e. having the same geometry), different labels will not be used here for the corresponding features of the end portion at the lower end of the valve member 6. For the avoidance of doubt, the first end portion 38 of the valve member 6 may be located at either an upper end (i.e. actuator end) or a lower end (i.e. distal the actuator) of the valve member 6. As mentioned, like end portions may be present at both ends of the valve member 6.

Even briefly comparing Figures 10 and 11 it will be appreciated that a minimum clearance at this 80% closed configuration is significantly greater for the valve member 6 (108) in comparison to the baseline valve member 200 (220).

Specifically, the clearance between the first vertex 92 and a corresponding point 110 of the internal surface of the conduit 8 is labelled 108. The clearance 108 is around 0.5 mm in the illustrated embodiment (~0.3 mm greater than the clearance 220 in Figure 10). A clearance 112 is also indicated between the second (i.e. trailing) vertex 94 and a corresponding point on the conduit 8. For the avoidance of doubt, a closing direction of the valve member 6 is labelled 114 in Figure 11 , and an opening direction is labelled 116.

As previously described, the first outer edge 96, extending between the first and second vertices 92, 94, is substantially parallel (e.g. to within around 0.5° of parallel) with a corresponding edge 118 of the conduit 8 when the valve member 6 in the fully closed configuration. The same applies for the second outer edge 102 of the second projection 54. Similar to that described in connection with Figure 10, although not described in detail in connection with Figure 11, corresponding clearances exist at the other side of the first end portion 34 (i.e. corresponding to the second projection 54).

When Figure 11 is considered in combination with Figure 5, where first to fourth quadrants 70, 72, 74, 96 are indicated, it will be appreciated that because the first end portion 34 is located largely outside of the second and fourth quadrants 72, 76, unlike the first end portion 208 of the baseline valve member 200, a clearance 108 defined between the first, leading vertex 92 and the conduit 8 is increased significantly in comparison to the clearance 220 between the first, leading vertex 222 and the conduit 8. This advantageously allows for a greater extent of thermal expansion between the conduit 8 and the valve member in use before sticking occurs. In effect, sticking of the valve member 6 is thus alleviated in operation.

Described another way, a point of minimum clearance, or pinch point, for the first end portion 34 is shifted to the other side of the mid-plane 66 as labelled in Figure 5 in Figure 11 in comparison to Figure 10. Furthermore, the point of minimum clearance for the first end portion 34 is realised when the valve member 6 has rotated to the fully closed configuration. Described another way, unlike Figure 10, a point of minimum clearance is not realised when the valve member 6 is rotated partway between the fully open and fully closed configurations.

Whilst the specific geometry of the first end portion 34 has been described here in detail, it will be appreciated that a range of other geometries could otherwise be used in which the same effect is achieved. For example, turning briefly to Figure 5, third and fourth recesses 62, 64 could be eliminated (i.e. the first end portion be solid in these areas) and the same effect still be achieved. The various recesses could also be deeper (e.g. such that the first end portion effectively extends a greater extent from a bulk of the valve member 6). The first end portion 34 may also have a more uniform geometry in other embodiments (e.g. wall thicknesses may be more uniform, desirable for reasons of improved thermomechanical fatigue performance.

Also of note, the clearances described and shown in connection with Figures 10 and 11 are simplified to aid explanation. It will be appreciated that, in practice, a smallest clearance (for a given rotational position of the valve member) may not lie in a plane normal to the first end portion. The clearance may exist in any direction, between the vertex and a corresponding nearest point on the conduit. It will therefore be appreciated that a direction of the clearance (e.g. if a line were to be drawn between the points) may with the opening/closing of the valve member. For reference, minimum clearance refers to a lowest clearance realised during the entire travel of the valve member (e.g. between the fully open and fully closed configurations). Smallest clearance refers to the lowest clearance realised at that given rotational position of the valve member. That is to say, the minimum clearance corresponds to the smallest clearance when the valve member is in the fully closed configuration for the valve member 6.

Turning to Figure 12, a front view of part of a butterfly valve assembly comprising the baseline valve member 200 is provided. Figure 12 is shown from the upstream end of the conduit 8. Figure 12 shows the baseline valve member 200 in a fully closed configuration (i.e. 100% closed). Figure 13 shows a front view of a butterfly valve assembly 2 incorporating the valve member 6 according to the invention. The Figure 12 and 13 views are schematically indicated 107 on Figure 9.

Both valve members 200, 6 of Figures 12 and 13 are shown in the fully closed (i.e. 100% closed) configurations. With the magnified views showing the lower end of the butterfly valve assemblies, it will be appreciated that the effective flow area through the conduit 8 (i.e. the cross-sectional area not blocked by the valve members 200, 6) is almost identical for both the baseline valve member 200 and the valve member 6. It will be appreciated that a small, effectively open area does still exist around the valve members, and so even in the fully closed configuration the valve members do not completely seal the conduit. This small clearance is provided in order to be able to operate the valve. Figure 13 indicates that even with the modified first end portion geometry as shown in Figures 8 and 11 , the extent to which the valve member 6 blocks the conduit 8 is not negatively impacted (i.e. leakage is not significantly increased). Described another way, the effective flow area when the valve member 6 is in the fully closed configuration is effectively the same as that of the baseline valve member 200. Described another way, a silhouette, or footprint, of the valve member 6 therefore remains effectively the same when viewed from the front. The sealing capability of the valve member 6 therefore effectively mirrors that of the baseline valve member 200, but potential issues with the end portion of the valve member sticking, owing to an insufficient level of clearance, are alleviated. A minimum clearance between (a vertex of) the first end portion and a closest point on the conduit is indicated 113 in Figure 13.

Turning to Figures 14 and 15, front views of the butterfly valve assemblies comprising the baseline valve member 200 and the valve member 6 respectively are provided. In Figures 14 and 15 the valve members are shown at an 80% closed configuration.

As indicated by the ellipses labelled 232 and 120 respectively, when the valve member is provided at an 80% closed position there is a slight increase in the effective flow area defined by the valve member 6 in comparison to the baseline valve member 200. This effectively means there is a slight sealing penalty associated with the valve member 6 at this exact position. However, it is important to note that the same back pressure across the valve member 6 can be achieved but this may simply require a slight adjustment of the valve position (i.e. in order for the back pressure to reach the same levels that are provided by the baseline valve member 200, the valve member 6 may need to be slightly more closed than the baseline valve member 200). Furthermore, the slight penalty is still very much preferable in comparison to changing a height of the valve member 6, and specifically by reducing the offset between the end portion and the major blocking surface, because doing so increases the effective flow area throughout the entire sweep, or travel, of the valve member 6. This also includes when the valve member is in a fully closed configuration. For these reasons, and those previously described, it is therefore desirable that a height of the valve member 6 remain unchanged in comparison to the baseline valve member 200. A smallest clearance (between a vertex of the first end portion and a closest point on the conduit) is indicated 115 in Figure 15. It will be appreciated that the clearance 115 in Figure 15 is greater than the (minimum) clearance 113 in Figure 13.

Figures 16a-d effectively correspond to that shown in Figure 10, relating to the first end portion 208 of the baseline valve member 200. However, Figures 16a-d show the arrangement as the baseline valve member 200 rotates from a 70% closed configuration (Figure 16a) to a 100% fully closed configuration (Figure 16d). Similarly, Figures 17a to 17d correspond to the embodiment shown in Figure 11 , but show the valve member 6 being rotated through from a 70% closed configuration (Figure 17a) to a fully closed configuration (Figure 17d). By comparing Figures 16a to 17d it will be appreciated that a point of minimum clearance between the end portion of the baseline valve member 200 and the conduit 8 occurs when the baseline valve member 200 is in the 80% closed configuration (Figure 16b). In contrast, the minimum clearance between the end portion of the valve member 6 and the conduit 8 only occurs when the valve member 6 has reached the 100% closed (i.e. fully closed) configuration (Figure 17d). For completeness, the first and second vertices 222, 226 (which may otherwise be referred to as the leading and trailing vertices respectively) of the baseline valve member 200 of the end portion 208 of the baseline valve member 200 are labelled. Similarly, first and second vertices 92, 94 of the end portion 34 for the valve member 6 are also labelled.

Finally, in connection with Figure 17d it will be appreciated that each of the first and second outer edges 96, 102 of the first end portion 34 of the valve member 6 align substantially parallel with corresponding edges of the conduit 8 when the valve member 6 is in the fully closed configuration. A radial line 236 is shown in Figures 16a- d extending from the axis of rotation to the first, leading vertex 222. The radial line 236 thus indicates the distance from the axis of rotation to the vertex which defines the point of minimum clearance (i.e. Figure 16b). Similarly, in Figures 17a-d a radial line 122 is indicated extending from the axis of rotation to the first, leading vertex 92. Again, the radial line 122 schematically indicates the radial position of the point of minimum clearance on the first end portion 34 relative to the axis.

Turning now to Figure 18, a plot showing the variation of clearance of each of the leading and trailing vertices for each of the valve members 6, 200 shown in Figures 7 and 8 is provided. In particular, the variation of the clearances from these vertices to a closest point of the conduit, specifically an internal surface thereof, is provided and shown varying with the position of the valve member. On the X axis the percentage closed (i.e. position) for the valve member is provided. On the Y axis, a clearance to the conduit in millimetres is provided. Four different data series are provided as indicated by the legend.

Figure 18 illustrates how the leading vertex of the baseline valve member has a lowest clearance when the valve member is at an 80% closed configuration as labelled 300. In contrast, for embodiments of the invention, the leading vertex of the valve member 6 has a minimum clearance to the conduit only when the valve member is in the closed configuration as labelled 302. Figure 18 therefore indicates that, advantageously according to the invention, a point of minimum clearance to the conduit from the leading vertex is shifted from a part-closed configuration to a fully closed configuration of the valve member. This eliminates the risk of the valve member sticking during significant thermal transients, where relative thermal expansion may otherwise risk distortion and a contacting/sticking of the valve member within the conduit. Of note, and as mentioned above, the various points of smallest clearance may not all lie in the same plane and, more likely, a direction of the smallest clearance (e.g. if a line were drawn between the vertex and the portion of the conduit closest to the vertex) may vary with rotation of the valve member. Similarly, a point on the conduit, closest to the vertex, may vary with rotation of the valve member.

Figure 19 is a table of values used to plot Figure 18.

The terms position and configuration are used interchangeable throughout this document. For example, a closed position of the valve member may otherwise be described as a closed configuration.

The shaft is preferably manufactured from stainless steel.

The described and illustrated embodiments are to be considered as illustrative and not restrictive in character, it being understood that only preferred embodiments have been shown and described and that all changes and modifications that come within the scope of the inventions as defined in the claims are desired to be protected. In relation to the claims, it is intended that when words such as "a," "an," "at least one," or "at least one portion" are used to preface a feature there is no intention to limit the claim to only one such feature unless specifically stated to the contrary in the claim. When the language "at least a portion" and/or "a portion" is used the item can include a portion and/or the entire item unless specifically stated to the contrary.

Optional and/or preferred features as set out herein may be used either individually or in combination with each other where appropriate and particularly in the combinations as set out in the accompanying claims. The optional and/or preferred features for each aspect of the invention set out herein are also applicable to any other aspects of the invention, where appropriate.