VALVE BODY AND SELF-OPERATED VALVE COMPRISING SAID VALVE BODY

Abstract

A self-operated valve includes a valve body (10) and a seat (28). The valve body comprises: (i) a seat mating portion; (ii) an elastomer support portion; (iii) a circumferential tip; (iv) an upper sealing member (92) having a lower surface (94) inclined toward the circumferential tip and a vent; (v) an internal corner where the elastomer support portion and the lower surface of the upper sealing member meet; (vi) an elastomeric seal (54); and (vii) an expansion cavity.The elastomeric seal has (a) a lower external contact surface, (b) an upper external contact surface that abuts the lower surface (94) of the upper sealing member (92) and extends beyond the circumferential tip, (c) an internal contact surface mounted on the elastomer support portion as a press fit and extending from the circumferential tip to at least 60% of the length of the elastomer support portion and sliding upward from the elastomer support portion in the valve closure.

Description

[0001] VALVE BODY AND SELF-ACTUATED VALVE COMPRISING SAID VALVE BODY

[0002] FIELD OF INVENTION

[0003] This invention relates to a self-actuated valve. It also relates to a pump including that self-actuated valve.

[0004] BACKGROUND OF THE INVENTION

[0005] One type of valve is a self-actuated valve. A self-actuated valve is designed to open when there is only a small pressure differential across the valve, such as less than 100 kPa (1 bar). This pressure differential only has to overcome the force acting to close the valve, which is typically gravitational force and the force of a spring that urges the valve to the closed position. Unlike actuated valves, that can open when there is a large pressure difference across the valve, a self-actuated valve has specific design constraints.

[0006] One particularly important aspect of a self-actuated valve is that the valve should close quickly to improve the volumetric efficiency of the pump incorporating the valve. The volumetric efficiency is the ratio of the actual flow rate that the pump delivers to the theoretical discharge flow rate. An inherent feature of a self-actuated valve is that the flow of fluid is already reversed before the valve is closed. Any further delay in closing the valve lowers the volumetric efficiency of the pump.

[0007] Self-actuated valves have been available for many decades, and there are many design variations of these valves.

[0008] One particularly challenging environment for self-actuated valves to operate in is in pumping slurries. Slurries are two-phase fluids that include solid particles suspended in liquid, for example, as a paste or as a settling slurry. Slurries typically have a solids concentration of at least 5% by weight. In valves, abrasive wear is typically the dominant wear type (particularly at the area where the valve seat meets the valve body), and is particularly problematic when pumping slurries having a relatively high solids concentration of hard or abrasive particles. Self-actuated valves are not suitable for use in pumping pastes, such as slurries having a solids concentration above approximately 60% by volume.

[0009] Prior art self-actuated valves that include an elastomeric seal have had problems when used in slurry pumping applications. High levels of wear are experienced as a result of trapped slurry between the elastomeric seal and the elastomer support portion of the valve body. When the valve is closed, and the pressure rises, this trapped slurry is forces „ough the surface contact area between the elastomer support portion and the elastomeric seal. This results in grooves at the intersection of the valve body and the valve seat, and grooves in the elastomer support portion. These grooves in the elastomer support portion reduce the effectiveness of the elastomer support portion in supporting the elastomeric seal when the valve is closed. This can cause tearing, which looks like nibbling of the elastomeric seal. These two wear patterns (grooving and nibbling) are more severe at higher discharge pressures (e.g. at 8 MPa (80 Bar) or above) or larger valve diameters (e.g. 100 mm or above), and eventually cause valve wash-out, which is critical failure of the valve such that the valve can no longer prevent fluid flow therethrough.

[0010] It is desirable to obviate or mitigate these wear patterns in self-actuated valves having elastomeric seals.

[0011] It is among the objects of an embodiment of this invention to provide means which may at least ameliorate this problem or provide a useful alternative.

[0012] SUMMARY OF THE INVENTION

[0013] This summary is provided to introduce a selection of concepts that are further described in the detailed description below. This summary is not intended to identify indispensable features of the claimed subject matter, nor is it intended for use as an aid in limiting the scope of the claimed subject matter.

[0014] In this application ordinal numbers (first, second, third, etc.) are assigned arbitrarily herein, and are used to differentiate between parts, and do not indicate a particular order, sequence, or importance.

[0015] According to a first aspect of the invention there is provided a self-actuated valve comprising: a valve seat and a valve body for positioning in a flow path; the valve body defining a longitudinal axis and comprising: (i) a seat engagement portion at a lower part thereof extending radially outwards at an angle, (ii) an elastomer support portion extending from an upper portion of the seat engagement portion radially inwards at an angle of between 30 and 40 degrees to the longitudinal axis, (iii) a circumferential nose at which the seat engagement portion meets the elastomer support portion (iv) an upper closing member having a lower surface inclined towards the circumferential nose at an angle of between 0.5 and 5 degrees to a line perpendicular to the longitudinal axis, and extending radially beyond the circumferential nose, the upper closing member defining a vent therein and extending therethrough; (v) an internal corner where .. elastomer support portion and the lower surface of the upper closing member meet; (vi) an elastomeric seal having (a) a lower external contact surface complementary to and abutting against the valve seat when the valve body is in its closed position, (b) an upper external contact surface abutting against the lower surface of the upper closing member and extending beyond the circumferential nose, (c) a central external surface extending between the upper external contact surface and the lower external contact surface, and (d) an internal contact surface mounted on the elastomer support portion as an interference fit and extending from the circumferential nose to at least 60% of the length of the elastomer support portion; and (vii) an expansion cavity defined by the lower surface of the upper closing member, the elastomer support portion, the internal corner, and the elastomeric seal, the expansion cavity being in fluid communication with the vent defined by the upper closing member so that when the valve body closes, the internal contact surface slides up the elastomer support portion and into the expansion cavity, whereas the upper external contact surface resists sliding to remain substantially in place.

[0016] A projected length of the elastomer support portion (the projected elastomer support portion length) comprises a length from the circumferential nose to a point (the intersection point) at which a linear projection of the elastomer support portion meets a linear projection of the lower surface of the upper closing member. The intersection point may be behind (radially inwards from) the expansion cavity.

[0017] Optionally, the internal corner may define an arcuate cross-section. The arcuate cross-section may comprise a radius of between 5 and 9 percent (in some embodiments, between 7 and 8 percent) of the projected elastomer support portion length. Where the internal corner comprises an angle equal to the angle between the elastomer support portion and the lower surface of the upper closing member, then the internal corner is effectively a line and the projected elastomer support portion length is approximately equal the actual elastomer support portion length.

[0018] The intersection point may be behind (radially inwards from) the internal corner. Optionally, the lower surface of the upper closing member is inclined towards the circumferential nose at an angle to a line perpendicular to the longitudinal axis of between 1 and 4 degrees, between 1.5 and 3 degrees, or at approximately 2.5 degrees. Optionally, the seat engagement extends radially outwards at an angle of between 34 and 36 degrees to the longitudinal axis; or at approximately 35 degrees to the longitudinal axis.

[0019] Optionally, the elastomer support portion extends from an upper portion of the seat engagement portion radially inwards at an angle of between 33 and 37 degrees to the longitudinal axis, or between 34 and 36 degrees to the longitudinal axis; or at approximately 35 degrees to the longitudinal axis.

[0020] The internal contact surface is defined as that part of the elastomeric seal that is in contact with the elastomer support portion.

[0021] Optionally, the internal contact surface extends at an angle to the longitudinal axis (the internal contact surface angle) slightly smaller (for example, between 0.5 and 4 degrees smaller) than the elastomer support portion angle. This ensures that there is a uniform contact stress by the interference fit between the internal contact surface and the elastomer support portion. Optionally, the internal contact surface angle is between 30 and 35 degrees to the longitudinal axis; or at approximately 33 degrees to the longitudinal axis. Providing a slightly smaller angle for the internal contact surface (than the elastomer support portion angle) generates a uniform, distributed contact stress; whereas, if the same angle is used for the internal contact surface as the elastomer support portion angle, there will be a lower contact stress at the circumferential nose, potentially leading to ingress of particles from the slurry (which would create wear). Optionally, the higher range of internal contact surface angles is used for larger diameter elastomeric seals to ensure that the contact stress is not lower at the circumferential nose, which is where solid particle ingress is prevented.

[0022] Optionally, the elastomeric seal is pre-stressed (stretched) as a result of being mounted on the elastomer support portion as an interference fit.

[0023] Optionally, the internal contact surface extends from the circumferential nose to at least 61 %, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71 %, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% or 90% of the length of the elastomer support portion (i.e. the distance from the circumferential nose to the start of the internal corner).

[0024] Optionally, the internal contact surface extends from the circumferential nose to at least 45% of the projected length of the elastomer support portion (which is the distance from the circumferential nose to the intersection point). Optionally, the internal contact su. extends from the circumferential nose to at least 45%, 46%, 47%, 48%, 49%, 50%, 51 %, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61 %, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, or 70% of the projected length of the elastomer support portion (which is the distance from the circumferential nose to the intersection point).

[0025] The upper closing member may comprise a nut threaded onto a stem of the valve body or a cap bolted (or otherwise fixed) to the top of the valve body. Alternative types of upper closing members may be used.

[0026] Optionally, the seat engagement portion angle is between 30 and 60 degrees to the longitudinal axis, in some embodiments, between 30 and 40 degrees, in other embodiments, between 33 and 36 degrees.

[0027] That part of the elastomeric seal that is in contact with the lower surface of the upper closing member and radially furthest from the longitudinal axis may be referred to as the “distal upper contact point”.

[0028] The upper external contact surface is defined as that part of the elastomeric seal that is in contact with the lower surface of the upper closing member. That part of the upper external contact surface that is in contact with the lower surface of the upper closing member and radially closest to the longitudinal axis may be referred to as the “proximal upper contact point”.

[0029] That part of the elastomeric seal that is in contact with the internal contact surface of the elastomeric seal and radially closest to the longitudinal axis may be referred to as the “proximal internal contact point”.

[0030] Optionally, the upper external contact surface extends radially beyond the circumferential nose by at least 2%, at least 2.5%, or at least 3%, when the valve is in the open position. These percentages relate to the radial width of the distal upper contact point compared with the radial width of the circumferential nose.

[0031] The circumferential nose may also be referred to as the tip.

[0032] The distance from the intersection point to the distal upper contact point may be referred to as the “projected upper seal length”.

[0033] Optionally, the length of the upper external contact surface is at least 30% of the projected upper seal length. Optionally, the length of the upper nal contact surface is between 30% and 60%, between 32% and 50%, or between 32% and 45% of the projected upper seal length.

[0034] Optionally, the length of the internal contact surface is at least 45% of the projected elastomer support portion length.

[0035] Optionally, the length of the internal contact surface is between 45% and 50%, between 51 % and 56%, or between 57% and 60% of the projected elastomer support portion length.

[0036] Optionally, the elastomeric seal defines an arcuate surface between the upper external contact surface and the internal contact surface. The arcuate surface may comprise a convex surface. The arcuate surface may comprise a radius of between 15 and 25 percent (in some embodiments, between 18 and 21 percent) of the projected elastomer support portion length.

[0037] Optionally, the expansion cavity defines a generally crescent shape in crosssection.

[0038] Optionally, the expansion cavity defines a projected upper length along the lower surface of the upper closing member to the intersection point, and a projected lower length along the elastomer support portion towards the intersection point.

[0039] Optionally, the expansion cavity projected upper length is longer than the length of the upper external contact surface by at least 35%, 40%, 50%, 60%, 65%, 66%, 67%, 68%, 69%, 70%, 71 %, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 85%, or 88%.

[0040] Optionally, the ratio of the expansion cavity projected lower length to the length of the internal contact surface is between 0.56 and 0.79, between 0.62 and 0.69, between 0.63 and 0.68, or between 0.64 and 0.68.

[0041] Optionally, the ratio of the length of the upper external contact surface to the length of the internal contact surface is between 0.2 and 0.3; between 0.22 and 0.28; or between 0.23 and 0.27.

[0042] The combination of the features of (i) the elastomeric seal being pre-stressed (stretched) as a result of being mounted on the elastomer support portion as an interference fit and extending from the circumferential nose to at least 60% of the length of the elastomer support portion, and (ii) the upper external contact surface abutting against the lower surface of the upper closing member and extending beyond the circumferential nose, result in creating maintaining the contact stresses of the elastomeric seal at the elastomer support portion. This ensures a close fit between the elastomeric seal and the elastomer support portion. This close fit prevents, or at least greatly reduces, ingress of particles in the fluid passing through the flow path between the internal contact surface and the elastomer support portion. This close fit minimises the amount of fluid trapped when closing the valve. Such trapped fluid is squeezed out during pressure build-up (when the valve has been closed). This squeezing creates a high flow velocity in the mating contact surfaces (i.e. the internal contact surface and the elastomer support portion over which the internal contact surface is mounted). If the internal contact surface and the elastomer support portion were not maintained in close contact, then the high flow velocity of particles would create erosional grooves in the internal contact surface or the elastomer support portion. These grooves would be enlarged on successive cycles of the valve because the volume of material eroded increases. This would result in the elastomer support portion not being able to support the elastomeric seal property, eventually leading to damage and failure of the elastomeric seal and the valve. By preventing or reducing such particle ingress, wear of the elastomeric seal or the elastomer support portion is greatly reduced. Absence of wear means that there is no increase in volume between the elastomeric seal and the elastomer support portion (since wear removes material from these surfaces). This greatly reduces the creation of erosional grooves therein; thereby greatly reducing failure modes of the valve body.

[0043] The elastomeric seal extending from the circumferential nose to at least 60% of the length of the elastomer support portion has the advantage that friction between the internal contact surface and the elastomer support portion makes it difficult to deform the elastomeric seal into the expansion cavity. In particular, the annular shape of the elastomeric seal makes it difficult to deform radially. Having an elastomer support portion angled between 33 and 37 degrees to the longitudinal axis makes it easier to deform the elastomeric seal into the expansion cavity. The combination of this deformation into the expansion cavity, the angle of the elastomer support portion, and the small downward angle of the lower surface of the upper closing member also ensures that there is minimal sliding over the lower surface of the upper closing member with limited lateral expansion at each side of the upper external contact surface. This combination ensures that there are primarily longitudinal forces being applied at the upper external contact sur,^.^^, thereby ensuring that there is minimal sliding of the elastomer over the upper closing member. Instead, there is limited lateral expansion of the upper external contact surface (a small percentage increase in the surface area of the elastomeric seal that is in contact with the lower surface of the upper closing member). This greatly reduces ingress of particles, and therefore erosion and wear.

[0044] Optionally, the upper external contact surface includes (i) a central static portion that does not move relative to the lower surface of the upper closing member when the valve moves from the open to the closed position, and (ii) lateral sliding portions on either side of the central static portion.

[0045] Optionally, the lateral expansion of the upper external contact surface is between 0.5mm and 10mm. More specifically, the lateral expansion of the upper external contact surface may be between 0.5mm and 5mm. It should be appreciated that the lateral expansion may differ based on how the elastomeric seal is deformed which may change due to wear of the elastomeric seal, valve seat and elastomer support portion. The lateral expansion is also affected by the resistance of the fluid within the expansion cavity against flowing out of the cavity through the vent. Fluid in the vent and / or cavity with a high viscosity (for example slurry) which has a high resistance against flowing out of the cavity will limit the inward lateral expansion causing the upper external contact surface to have an increased outward lateral expansion. The total deformation of the elastomeric seal over its entire cross-section ensures low additional stresses and strains. Deformation is spread over the entire seal cross section. If this was attempted with prior art (e.g. clamped valve ring) designs, local high stresses and strains would cause tears and preliminary failure of the valve.

[0046] One advantage of having an expansion cavity in fluid communication with the vent is that it allows the elastomeric seal to deform into the expansion cavity when the valve is closed. It also, in general, allows for pressure equalisation on either side of the elastomeric seal because the generally higher pressure area above the valve is in fluid communication with the expansion cavity. In circumstances where a small particle is preventing complete closure of the valve, it also ensures that the elastomeric seal is moved to the correct sealing position by virtue of the pressure difference between the high pressure and low pressure side. The valve seat may comprise an ,, ,^gral portion of a support (such as the housing) or a removable part that can be replaced when worn.

[0047] The valve seat may be annular and arranged around the flow path such that the flow path extends therethrough. When the valve body is in the closed position, the valve seat may have a higher pressure side and a lower pressure side, the diameter of the valve seat may decrease for at least part of its length from the higher pressure side towards the lower pressure side. In one embodiment, the valve seat is frusto- conical in shape and has a constant angle of taper from its higher pressure side to its lower pressure side.

[0048] The elastomeric seal may be formed as a unitary moulding or casting of an elastomeric material, such as polyurethane rubber. For moulding the elastomeric seal, any other convenient elastomeric material may be used, such as Styrene-Butadiene Rubber (SBR), Ethylene Propylene Diene Monomer (EPDM) rubber, Fluroelastomer (FKM) rubber, Nitrile Butadiene Rubber (NBR), or Hydrogenated Acrylonitrile Butadiene Rubber (HNBR), depending on the slurry and temperatures being pumped.

[0049] Test results of valves made according to the first aspect have shown surprisingly good results. An increase in valve life of a minimum of 33% was recorded. Unlike prior valve designs, the elastomeric seal was not the limiting factor in the total valve life, thereby extending the valve life.

[0050] According to a second aspect of the invention there is provided a self-actuated valve body for use with a valve seat, the valve body comprising: (i) a seat engagement portion at a lower part thereof extending radially outwards at an angle, (ii) an elastomer support portion extending from an upper portion of the seat engagement portion radially inwards at an angle of between 30 and 40 degrees to the longitudinal axis, (iii) a circumferential nose at which the seat engagement portion meets the elastomer support portion (iv) an upper closing member having a lower surface inclined towards the circumferential nose at an angle of between 0.5 and 5 degrees to a line perpendicular to the longitudinal axis, and extending radially beyond the circumferential nose, the upper closing member defining a vent therein and extending therethrough; (v) an internal corner where the elastomer support portion and the lower surface of the upper closing member meet; (vi) an elastomeric seal having (a) a lower external contact surface complementary to and abutting against the valve seat when the valve body is in its closed position, (b) an upper external contact surface abutting against the lower surface of the upper u.^..ig member and extending beyond the circumferential nose, (c) a central external surface extending between the upper external contact surface and the lower external contract surface, and (d) an internal contact surface mounted on the elastomer support portion as an interference fit and extending from the circumferential nose to at least 60% of the length of the elastomer support portion; and (vii) an expansion cavity defined by the lower surface of the upper closing member, the elastomer support portion, the internal corner, and the elastomeric seal, the expansion cavity being in fluid communication with the vent defined by the upper closing member so that when the valve body closes, the internal contact surface slides up the elastomer support portion and into the expansion cavity, whereas the upper external contact surface resists sliding to remain substantially in place.

[0051] Optionally, the elastomeric seal is pre-stressed (stretched) as a result of being mounted on the elastomer support portion as an interference fit.

[0052] Optionally, the upper external contact surface resists sliding and limits lateral expansion at each side of the upper external contact surface.

[0053] According to a third aspect of the invention there is provided a pump including one or more self-actuated valves according to the first aspect of the invention.

[0054] According to a fourth aspect of the invention there is provided a self-actuated valve comprising: a valve seat and a valve body for positioning in a flow path; the valve body defining a longitudinal axis and comprising: (i) a seat engagement portion at a lower part thereof extending radially outwards at an angle, (ii) an elastomer support portion extending from an upper portion of the seat engagement portion radially inwards at an angle of between 30 and 40 degrees to the longitudinal axis, (iii) a circumferential nose at which the seat engagement portion meets the elastomer support portion (iv) an upper closing member having a lower surface, and extending radially beyond the circumferential nose, the upper closing member defining a vent therein and extending therethrough; (v) an internal corner where the elastomer support portion and the lower surface of the upper closing member meet; (vi) an elastomeric seal having (a) a lower external contact surface complementary to and abutting against the valve seat when the valve body is in its closed position, (b) an upper external contact surface abutting against the lower surface of the upper closing member and extending beyond the circumferential nose, (c) a central external surface extending between the upper external co. surface and the lower external contact surface, and (d) an internal contact surface mounted on the elastomer support portion as an interference fit and extending from the circumferential nose to at least 60% of the length of the elastomer support portion; and (vii) an expansion cavity defined by the lower surface of the upper closing member, the elastomer support portion, the internal corner, and the elastomeric seal, the expansion cavity being in fluid communication with the vent defined by the upper closing member so that when the valve body closes, the internal contact surface slides up the elastomer support portion and into the expansion cavity, whereas the upper external contact surface resists sliding to remain substantially in.

[0055] Optionally, the upper external contact surface resists sliding and limits lateral expansion at each side of the upper external contact surface.

[0056] It should be appreciated that angles selected within the ranges described above have been shown to provide significantly improved performance of valves, particularly when used to pump slurries.

[0057] BRIEF DESCRIPTION OF THE DRAWINGS

[0058] These and other aspects of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

[0059] Figure 1 is a sectional elevation view of a self-actuated valve in accordance with an embodiment of the invention, where the valve is in a closed position;

[0060] Figure 2 is a sectional elevation view of the valve of Figure 1 , where the valve is in an open position;

[0061] Figure 3 is a perspective view of the valve body of Figure 1 ;

[0062] Figure 4 is a sectional elevation view of the valve body of Figure 3;

[0063] Figure 5 is a perspective view of the valve body of Figure 3, but with a part (the elastomeric seal) removed;

[0064] Figure 6 is a sectional elevation view of the valve body of Figure 5 with the elastomeric seal removed;

[0065] Figure 7 is an enlarged sectional view of the elastomeric seal (with a central part removed for clarity);

[0066] Figure 8 is an enlarged view of part of the valve of Figure 2, showing parts in greater detail; and Figure 9 is a pictorial view of a pa. . . ,e elastomeric seal) of Figure 1 in three different conditions (unmounted, mounted with the valve open, mounted with the valve closed).

[0067] DETAILED DESCRIPTION OF EMBODIMENTS

[0068] Reference will now be made to the drawings, in which reference numeral 10 indicates a self-actuated valve according to one embodiment of the present invention. The self-actuated valve 10 defines a longitudinal axis 12, and includes a housing, part of which is shown in the drawings and is generally indicated by reference numeral 20. A first fluid port, indicated generally by numeral 22 (in this embodiment an inlet), and a second fluid port, indicated generally by numeral 24 (in this embodiment an outlet) are each defined by the housing 20, and a flow path extends through the housing 20 and connects the fluid ports 22, 24 in flow communication. In this embodiment, the inlet 22 is oriented transverse (perpendicular) to the outlet 24. In Figure 1 , the outlet 24 is actually formed by that part of the housing 20 that has been removed to show the cross section.

[0069] The housing 20 defines a chamber 26 through which fluid, particularly slurry containing particles, is transported from the inlet 22 to the outlet 24. In this embodiment, the solids concentration of the slurry is approximately 35% by weight.

[0070] The valve 10 further includes a valve seat, generally indicated by reference numeral 28, which is positioned between the two fluid ports 22, 24. In one embodiment, the valve seat 28 may be formed by a hardened surface in the housing. In another embodiment, shown in the drawings, the valve seat 28 is formed by an insert mounted on the housing 20 which facilitates replacement of the valve seat 28 when worn. A pair of elastomeric O-rings 30 are located between the valve seat 28 and the housing 20. A fluid channel 32 is provided to allow hydraulic fluid to assist in removing the valve seat 28 when desired.

[0071] The valve seat 28 is a conventional annular valve seat, and defines a part of the flow path. The valve seat 28 comprises a frusto-conical upper portion 40 having a narrow end 42 and a wider end 44, and a generally cylindrical lower portion 46 extending downwards from the narrow end 42 of the frusto-conical portion 40. In other embodiments, the valve seat 28 may have a different shape.

[0072] The valve 10 further includes a valve body 50 comprising: a central body portion 52; a valve ring (in the form of an elastomeric seal in this embodiment) 54 mounted on the central body portion 52 as an inter. ice fit; and alignment legs 56 extending downwards from the central body portion 52 to assist with centralising the valve body 50 when the valve 10 is opening and closing. In this embodiment, the alignment legs 56 are friction welded to the central body portion 52. In this embodiment, the central body portion 52 is a unitary cast component, but in other embodiments it may comprise separable components and may be manufactured using other techniques than casting, e.g. forging, and connected using any convenient technique (welding or the like).

[0073] A valve housing cover 60 is provided to close the chamber 26 above the valve body 50. A clamping plate portion 62 defines (i) a support portion 64 mounted to an underside of the valve housing cover 60, and (ii) cylindrical guide 66 extending downwards from the support portion 64, and located generally centrally thereon. The cylindrical guide 66 defines a central guide channel 68 therein, and an outer cylindrical surface 70. The central guide channel 68 is in fluid communication with the chamber 26. A wear resistant cylindrical guide bush 72 is mounted at an entrance of the central guide channel 68 as an interference fit thereto. A coil spring 74 is mounted around the outer cylindrical surface 70. In other embodiments, the cylindrical guide bush 72 may be mounted and held in place by a circlip.

[0074] The central body portion 52 defines a cylindrical stem portion 80 extending upwards along longitudinal axis 12. The cylindrical stem portion 80 is located within the central guide channel 68 and in sliding contact with the cylindrical guide bush 72. A lower part of the coil spring 74 is in contact with an upper part of the central body portion 52. The coil spring 74 is selected to prevent the valve body 50 from opening until a desired pressure differential is reached.

[0075] As best seen in Figures 4 and 6, the central body portion 52 defines a seat engagement portion 82 at a lower part thereof extending radially outwards at an angle 84 of between 30 and 40 degrees to a line parallel to the longitudinal axis 12, in this embodiment, angle 84 is approximately 35 degrees, but in other embodiments, the seat engagement portion angle 84 may be larger, such as between 40 and 60 degrees.

[0076] The central body portion 52 also defines an elastomer support portion 86 extending from an upper portion of the seat engagement portion 82 radially inwards at an angle 88 of between 30 and 40 degrees to a line parallel to the longitudinal axis 12, in this embodiment, angle 88 is approximately 35 degrees. The seat engagement portion 82 i.. ^s the elastomer support portion 86 at a circumferential nose (also called a tip) 90.

[0077] The central body portion 52 also defines an upper closing member 92 having a lower surface 94 inclined towards the circumferential nose 90 at an angle 96 (best seen in Figure 8) of between 0.5 and 5 degrees to a line perpendicular to the longitudinal axis 12. The upper closing member 92 extends radially beyond the circumferential nose 90 and defines a vent 98 therein and extending therethrough (best seen in Figures 3 to 6). In this embodiment, angle 96 is approximately 2.5 degrees. Although the upper closing member 92 is illustrated in the Figures as a unitary part of the valve body 52, in other embodiments, the upper closing member 92 may be a separable component, such as a cap or nut having a screw thread or other fixing mechanism.

[0078] As best seen in Figure 7, the elastomeric seal 54 has a lower external contact surface 100 complementary to and abutting against the valve seat 28 when the valve body 50 is in its closed position. The lower external contact surface 100 extends at approximately the same angle as the seat engagement portion angle 84 (approximately 35 degrees in this embodiment), but protrudes radially beyond the tip 90 (e.g. by a few millimetres, such as 3 mm) to ensure that the lower external contact surface 100 is in sealing engagement with the valve seat 28 when the valve 10 is in the closed position. This protrusion is best seen in Figure 8.

[0079] The elastomeric seal 54 also has an upper external contact surface 102 abutting against the lower surface 94 of the upper closing member 92 and extending beyond the circumferential nose 90, in this embodiment, by at least 2%, when the valve is in the open position.

[0080] A central external surface 104 extends between the upper external contact surface 102 and the lower external contact surface 100.

[0081] The elastomeric seal 54 also has an internal contact surface 106, and a convex expansion surface 108 extending between the upper external contact surface 102 and the internal contact surface 106. The internal contact surface angle 109 is a few degrees smaller than the elastomer support portion angle 88 (in this embodiment approximately 2 degrees smaller) so that the elastomeric seal 54 is an uniform contact stress interference fit around the central body portion 52, which pre-stresses (stretches) the elastomeric seal 54 as a result of being mounted on the central body portion 52 as an interference fit. The in . . contact surface 106 is defined as that part of the elastomeric seal 54 that is in contact with the elastomer support portion 86. Deformation of the elastomeric seal 54 may cause the internal contact surface 106 to grow or shrink slightly.

[0082] As best seen in Figures 4 and 8, an expansion cavity 110 is defined by the lower surface 94 of the upper closing member 92, the elastomer support portion 86 and the elastomeric seal 54 (in particular, the convex expansion surface 108 thereof). The expansion cavity 110 is in fluid communication with one side of the vent 98. The other side of the vent 98 opens into the chamber 26.

[0083] Reference is now made particularly to Figure 9, which illustrates how the elastomeric seal 54 changes shape when mounted and during operation of the valve 10. The shapes shown in Figure 9 are particularly applicable to the elastomeric seal 54 when it is new, rather than after an extended period of use, although the general changes shown in Figure 9 are still valid for a worn elastomeric seal 54.

[0084] Prior to mounting the elastomeric seal 54 onto the central body portion 52, the seal 54 has the shape shown by broken line 112. Once the seal 54 has been mounted onto the central body portion 52, its shape changes, primarily by moving radially outwards, but also with the upper external contact surface 102 moving downwards, as shown by broken line 114. This results in an increase in the diameter of the elastomeric seal 54.

[0085] When the valve body 50 closes, the seal 54 has the shape shown by broken line 116. Closing the valve body 50 causes upwards force to be exerted by the valve seat 28 on the elastomeric seal 54, which causes the lower external contact surface 100 to move upwards and radially inwards, sliding along and up the elastomer support portion 86. The upper external contact surface 102 has limited lateral expansion at each side and expands at its edges by only a limited amount both laterally inwards (into the expansion cavity 110) and laterally outwards, along the lower surface 94, which results in negligible movement (no sliding over the length of the lower surface 94) along the central portion (i.e. the portion shown by double arrow 120 in Figure 9) of the upper external contact surface 102. The central external surface 104 moves radially outwards by a relatively small amount. The internal contact surface 106 moves upwards by sliding up the elastomer support portion 86 and into the expansion cavity 110. The convex expansion surface 108 moves radially inwards and upwards into the expansion cavity 110. When this ^urs, any slurry (or other pumped fluid) or air trapped in the expansion cavity 110 passes through the vent 98 into the chamber 26. Thus, as a result of the configuration of the central body portion 52 and the elastomeric seal 54, when the valve 10 is closed and the elastomeric seal 54 is compressed the internal contact surface 106 slides up the elastomer support portion 86 and into the expansion cavity 110; whereas the upper external contact surface 102 resists sliding along the lower surface 94 of the upper closing member 92 to remain substantially in place with limited lateral expansion at each side thereof. In this embodiment, the lateral expansion of the upper external contact surface 102 is between 0.5mm and 10mm laterally inwards and between 0.5mm and 5mm laterally outwards. The limited lateral expansion causes a limited percentage increase in the surface area of the elastomeric seal that is in contact with the lower surface of the upper closing member. It should be appreciated that the lateral expansion may differ based on how the elastomeric seal is deformed which may change due to wear of the elastomeric seal, valve seat and elastomer support portion.

[0086] The lateral expansion is also affected by the resistance of the fluid within the expansion cavity 110 against flowing out of the cavity 110 through the vent 98. Fluid in the expansion cavity 110 with a high viscosity (for example slurry), which has a high resistance against flowing out of the cavity, will limit the inward lateral expansion causing the upper external contact surface 102 to have an increased outward lateral expansion.

[0087] One of the reasons that wear is prevented or at least reduced is that the primary wear mode for valves is abrasive wear, and for abrasive wear to occur three components must be present: an abrasive (particles are present in the slurry), a pressure (the elastomeric seal 54 is compressed) and movement (although the upper external contact surface 102 expands at its edges, it does not slide).

[0088] By closing the valve 10, the elastomeric seal 54 is compressed (its external height is reduced), and solid particles in the slurry may be trapped between the valve seat 28 and the lower external contact surface 100 (and embedded in the lower external contact surface 100). There is also typically a differential pressure when the valve 10 closed. This differential pressure tends to extrude the elastomeric seal 54 into the lower pressure part (typically below the circumferential nose 90). The elastomeric seal 54 slides in . ^.dially inwards direction when the valve body 50 is closed but maintaining contact with the circumferential nose 90; whereas prior art designs only provide movement in the longitudinal direction and lose contact with the equivalent of the circumferential nose 90. This means that in those prior art designs the equivalent of the lower external contact surface 100 slides more (than the lower external contact surface 100 in this embodiment) when the valve 10 is closed in the presence of differential pressure.

[0089] Reference is now made particularly to Figure 8, which shows various dimensions of the valve body 50.

[0090] The elastomer support portion 86 and the lower surface 94 of upper closing member 92 meet at an internal corner 122. In this embodiment, the internal corner has an arcuate cross-section, as best seen in Figure 8. The arcuate cross-section defines a radius of less than 10 mm, although a different radius (or a different shape, such as an angled corner) may be selected in other embodiments.

[0091] Intersection point 124 is the point at which a line projected from the elastomer support portion 86 meets a line projected from lower surface 94 of the upper closing member 92. The intersection point 124 is behind (radially inwards from) the internal corner 122. However, the distance between the internal corner 122 and the intersection point 124 is enlarged in Figure 8 for clarity.

[0092] The upper external contact surface 102 is defined as that part of the elastomeric seal 54 that is in contact with the lower surface 94 of the upper closing member 92. The point of the upper external contact surface 102 radially furthest from the longitudinal axis 12 is the distal upper contact point 126; and the point that is radially closest to the longitudinal axis 12 is the proximal upper contact point 128.

[0093] The point of the internal contact surface 106 radially closest to the longitudinal axis 12 is the proximal internal contact point 130.

[0094] The distance from the intersection point 124 to the radially furthest point of the upper closing member 92 is the upper member length (shown by arrow 140).

[0095] The distance from the intersection point 124 to the distal upper contact point 126 is the projected upper seal length (shown by arrow 142). The distance from the distal upper contact point 126 to the proximal upper contact point 128 is the upper external contact surface length (shown by arrow 146, which approximates this length). In this embodiment, the upper ex , , , contact surface length 146 is at least 20% of the projected upper seal length 142. In other embodiments, the upper external contact surface length 146 may be less than 40% of the projected upper seal length 142.

[0096] The distance from the intersection point 124 to the proximal upper contact point 128 is the expansion cavity projected upper length (shown by arrow 144). In this embodiment, the expansion cavity projected upper length 144 is longer than the upper external contact surface length 146 by at least 150%. In other embodiments, the expansion cavity projected upper length 144 may be longer by a larger percentage than 150%. Optionally, the expansion cavity projected upper length 144 is longer than the upper external contact surface length 146 by at least 200%. Optionally, the expansion cavity projected upper length 144 is longer than the upper external contact surface length 146 by at least 250%. Optionally, the expansion cavity projected upper length 144 is longer than the upper external contact surface length 146 by at least 300%.

[0097] The distance from the intersection point 124 to the circumferential nose 90 is the projected elastomer support portion length (shown by arrow 148), even though the portion between the internal corner 122 and the intersection point 124 is not available to support the internal contact surface 106 of the elastomeric seal 54. In this embodiment, the internal contact surface 106 extends from the circumferential nose 90 along at least 45% of the projected elastomer support portion length 148. Stated another way, in this embodiment, the ratio of internal contact surface length 150 to the elastomer support portion length 148 is at least 0.45. In other embodiments, the internal contact surface 106 may extend even further along the elastomer support portion length 148, for example, with a ratio of at least 0.55.

[0098] The actual (not projected) elastomer support portion length 151 is the length from the circumferential nose 90 to the start of the internal corner 122.

[0099] The distance from the circumferential nose 90 to the proximal internal contact point 130 is the internal contact surface length (shown by arrow 150). In this embodiment, the ratio of the upper external contact surface length 146 to the internal contact surface length 150 is between 0.2 and 0.3; although in other embodiments, a larger range may be used, such as between 0.15 and 0.35. The distance from the circumferen.,^, , ,ose 90 to the longitudinal axis 12 is the tip diameter (shown by arrow 152). The distance from the distal upper contact point 126 to the longitudinal axis 12 is the elastomeric seal diameter (shown by arrow 154). The ratio of the elastomeric seal diameter 154 to the tip diameter 152 is approximately 1.03 in this embodiment. In other embodiments, this ratio may be selected from the range between 1.01 and 1.05.

[0100] The distance from the intersection point 124 to the proximal internal contact point 130 is the expansion cavity projected lower length (shown by arrow 156). In this embodiment, the ratio of the expansion cavity projected lower length 156 to the internal contact surface length 150 is approximately 0.79. In other embodiments, a different ratio may be selected, such as a ratio between 0.7 and 0.85.

[0101] In this embodiment, the internal contact surface 106 extends from the circumferential nose 90 along at least 60% of the elastomer support portion 86. Stated another way, in this embodiment, the ratio of internal contact surface length 150 to the elastomer support portion length 151 is at least 0.6. In other embodiments, the internal contact surface 106 may extend even further along the elastomer support portion 86, for example, with a ratio of internal contact surface length 150 to the elastomer support portion length 151 of at least 0.7.

[0102] During operation of the valve 10 (when the valve 10 is oriented as shown in Figures 1 and 2), as the pressure at the inlet 22 rises, the pressure differential across the valve body 50 increases. Once the forces of gravity and the spring force are exceeded by the pressure at the inlet 22, the valve body 50 moves upwards and fluid flows through the valve 10 until the pressure differential reduces and the force of the coil spring 74 is greater than the pressure difference, at which point the valve body 50 moves downwards and the valve 10 closes.

[0103] The valve 10 described above could be used in any convenient application, for example in a positive displacement pump. The valve 10 may be used as an inlet valve or an outlet valve, in any convenient orientation.

[0104] Various modifications to the above described embodiments may be made within the scope of the present invention. For example, many of the dimensions and ratios given above include a range from which a value can be selected; embodiments can be created using a different value from each of these ranges, thereby providing a very large number of unique embodiments. In other embodiments, the valve ...jy be mounted in an inverse orientation to that shown in Figures 1 and 2 (i.e. upside down), or at an angle. If mounted upside down then gravity will assist with opening the valve 10.

[0105] LIST OF REFERENCE NUMERALS

[0106] Self-actuated valve 10

[0107] Longitudinal axis 12

[0108] Housing 20

[0109] First fluid port (inlet) 22

[0110] Second fluid port (outlet) 24

[0111] Chamber 26

[0112] Valve seat 28

[0113] O-rings 30

[0114] Hydraulic fluid channel 32

[0115] Frusto-conical upper portion 40

[0116] Narrow end (of frusto-conical upper portion) 42

[0117] Wider end (of frusto-conical upper portion) 44

[0118] Cylindrical lower portion 46

[0119] Valve body 50

[0120] Central body portion (of valve body) 52

[0121] Valve ring (elastomeric seal) 54

[0122] Alignment legs (of valve body) 56

[0123] Valve housing cover 60

[0124] Clamping plate portion 62

[0125] Support portion (of clamping plate portion) 64

[0126] Cylindrical guide (of clamping plate portion) 66

[0127] Central guide channel (of cylindrical guide) 68

[0128] Outer cylindrical surface (of cylindrical guide) 70

[0129] Cylindrical guide bush (of cylindrical guide) 72

[0130] Coil spring 74

[0131] Cylindrical stem portion (of central body portion) 80

[0132] Seat engagement portion 82

[0133] Seat engagement portion angle 84

[0134] Elastomer support portion 86 Elastomer support portion angle 88

[0135] Circumferential nose (or tip) 90

[0136] Upper closing member (of central body portion) 92

[0137] Lower surface (of upper closing member) 94

[0138] Angle (of upper closing member) 96

[0139] Vent (in upper closing member) 98

[0140] Lower external contact surface (of valve ring) 100

[0141] Upper external contact surface (of valve ring) 102

[0142] Central external surface (of valve ring) 104

[0143] Internal contact surface (of valve ring) 106

[0144] Convex expansion surface (of valve ring) 108

[0145] Internal contact surface angle 109

[0146] Expansion cavity 110

[0147] Unmounted seal shape 112

[0148] Mounted seal shape 114

[0149] Closed seal shape 116

[0150] Central portion (of upper external contact surface) 120

[0151] Internal corner 122

[0152] Intersection point 124

[0153] Distal upper contact point 126

[0154] Proximal upper contact point 128

[0155] Proximal internal contact point 130

[0156] Upper member length 140

[0157] Projected upper seal length 142

[0158] Expansion cavity projected upper length 144

[0159] Upper external contact surface length 146

[0160] Projected elastomer support portion length 148

[0161] Internal contact surface length 150

[0162] Elastomer support portion length 151

[0163] Tip diameter 152

[0164] Elastomeric seal diameter 154

[0165] Expansion cavity projected lower length 156

Claims

22CLAIMS1 . A self-actuated valve comprising: a valve seat and a valve body for positioning in a flow path; the valve body defining a longitudinal axis and comprising:(i) a seat engagement portion at a lower part thereof extending radially outwards at an angle to the longitudinal axis;(ii) an elastomer support portion extending from an upper portion of the seat engagement portion radially inwards at an angle of between 30 and 40 degrees to the longitudinal axis;(iii) a circumferential nose at which the seat engagement portion meets the elastomer support portion;(iv) an upper closing member having a lower surface inclined towards the circumferential nose at an angle of between 0.5 and 5 degrees to a line perpendicular to the longitudinal axis, and extending radially beyond the circumferential nose, the upper closing member defining a vent therein and extending therethrough;(v) an internal corner where the elastomer support portion and the lower surface of the upper closing member meet;(vi) an elastomeric seal having(a) a lower external contact surface complementary to and abutting against the valve seat when the valve body is in its closed position,(b) an upper external contact surface abutting against the lower surface of the upper closing member and extending beyond the circumferential nose,(c) a central external surface extending between the upper external contact surface and the lower external contact surface, and(d) an internal contact surface mounted on the elastomer support portion as an interference fit and extending from the circumferential nose to at least 60% of the length of the elastomer support portion; and(vii) an expansion cavity defined by the lower surface of the upper closing member, the elastomer support portion, the internal corner, and theelastomeric seal, the expan^, , cavity being in fluid communication with the vent defined by the upper closing member so that when the valve body closes, the internal contact surface slides up the elastomer support portion and into the expansion cavity, whereas the upper external contact surface resists sliding to remain substantially in place.

2. The valve as claimed in claim 1 , wherein the internal corner defines an arcuate cross-section having a radius of less than 10 mm.

3. The valve as claimed in claim 1 or 2, wherein the lower surface of the upper closing member is inclined towards the circumferential nose at an angle to a line perpendicular to the longitudinal axis of less than four degrees.

4. The valve as claimed in any preceding claim, wherein the elastomeric seal is pre-stressed as a result of being mounted on the elastomer support portion as an interference fit.

5. The valve as claimed in any preceding claim, wherein the upper external contact surface expands laterally at each side thereof between 0.5mm and 10mm.

6. The valve as claimed in claim 5, wherein the lateral expansion of the upper external contact surface increases the surface area of the elastomeric seal that is in contact with the lower surface of the upper closing member.

7. The valve as claimed in any preceding claim, wherein the internal contact surface extends at an angle to the longitudinal axis between 0.5 and 4 degrees larger than the elastomer support portion angle.

8. The valve as claimed in any preceding claim, wherein the internal contact surface extends from the circumferential nose to at least 65% of the length of the elastomer support portion.

9. The valve as claimed in any preceding claim, wherein the upper external contact surface extends radially beyond the circumferential nose by at least 2% when the valve is in the open position.

10. The valve as claimed in any preceding claim, wherein the length of the upper external contact surface is at least 20% of a projected upper seal length.11 . The valve as claimed in any precet... .aclaim, wherein the length of the internal contact surface is at least 45% of a projected elastomer support portion length.

12. The valve as claimed in any preceding claim, wherein the elastomeric seal defines an arcuate surface between the upper external contact surface and the internal contact surface.

13. The valve as claimed in any preceding claim, wherein the expansion cavity defines a generally crescent shape in cross-section.

14. The valve as claimed in any preceding claim, wherein an expansion cavity projected upper length is longer than the length of the upper external contact surface by at least 150%.

15. The valve as claimed in any preceding claim, wherein a ratio of an expansion cavity projected lower length to the length of the internal contact surface is between 0.7 and 0.85.

16. The valve as claimed in any preceding claim, wherein the ratio of the length of the upper external contact surface to the length of the internal contact surface is between 0.2 and 0.3.

17. A pump including one or more self-actuated valves according to any of claims1 to 16.

18. A self-actuated valve body for use with a valve seat, the valve body comprising:(i) a seat engagement portion at a lower part thereof extending radially outwards at an angle to the longitudinal axis;(ii) an elastomer support portion extending from an upper portion of the seat engagement portion radially inwards at an angle of between 30 and 40 degrees to the longitudinal axis;(iii) a circumferential nose at which the seat engagement portion meets the elastomer support portion;(iv) an upper closing member having a lower surface inclined towards the circumferential nose at an angle of between 0.5 and 5 degrees to a line perpendicular to the longitudinal axis, and extending radially beyond the25 circumferential nose, the up ^, closing member defining a vent therein and extending therethrough;(v) an internal corner where the elastomer support portion and the lower surface of the upper closing member meet;(vi) an elastomeric seal having(a) a lower external contact surface complementary to and abutting against the valve seat when the valve body is in its closed position,(b) an upper external contact surface abutting against the lower surface of the upper closing member and extending beyond the circumferential nose,(c) a central external surface extending between the upper external contact surface and the lower external contract surface, and(d) an internal contact surface mounted on the elastomer support portion as an interference fit and extending from the circumferential nose to at least 60% of the length of the elastomer support portion; and(vii) an expansion cavity defined by the lower surface of the upper closing member, the elastomer support portion, the internal corner, and the elastomeric seal, the expansion cavity being in fluid communication with the vent defined by the upper closing member so that when the valve body closes, the internal contact surface slides up the elastomer support portion and into the expansion cavity, whereas the upper external contact surface resists sliding to remain substantially in.

19. The self-actuated valve body as claimed in claim 18, wherein the elastomeric seal is pre-stressed as a result of being mounted on the elastomer support portion as an interference fit.

Images