Valve assembly

Abstract

"VALVE SET". A valve assembly is designed to prevent or minimize the effect of "compression hardening" that occurs when valves control the flow of some dangerous and / or corrosive fluids, especially when at an elevated temperature. The valve assembly includes a valve stem that has a head part that contacts a valve seat in order to close and seal the valve and an elastically deformable part. In order to allow the fluid to flow through the valve, the elastically deformable part of the valve stem is deformed to allow fluid to pass between the head part and the valve seat. An element of additional propensity, such as, for example, a cylindrical or conical compression spring, is provided to urge the head portion towards contact with the valve seat. In this way, in case the "compression hardening" of the elastic part of the valve stem occurs, the additional spring will ensure that the valve head can still be brought into contact with the valve seat, in order to close the valve.

Description

VALVE ASSEMBLY TECHNICAL FIELD The present invention relates to valve assemblies and, in particular, though not exclusively, to spring-loaded self-closing valve assemblies used in the flow path of fluids. FUNDAMENTALS TECHNIQUE In fluid flow control systems where the fluid is highly corrosive or hazardous, it is extremely important that the fluid does not escape from its storage container (or any conduit connected to the storage container) where it could then come into contact with the user. It is particularly important that the connection between the storage container and the conduit is well sealed when the conduit is removed from the connection to the container. In such cases, it is common to incorporate a flow control valve at the outlet of the storage container that closes when the outlet conduit is disconnected. An example of this type of system is presented in the present applicant's New Zealand patent, No. 329181, in which the outlet conduit is fitted with a fitting that has a projection which, when connected to the outlet of the storage container, exerts downward pressure on the head of the rod assembly. The valve, thus opening the valve and allowing fluid 25 to flow from the container to the conduit (or vice versa). The valve stem inside the valve includes an elastically deformable part which, when the conduit connector is removed, provides the restoring force necessary to move the ► ······ « • · · · · valve stem head against the valve seat, thus closing the valve. Valves of the type described above are used for storing and controlling the flow of hazardous and / or corrosive fluids that may be kept at high temperatures. Since the valve seat is frequently submerged in the fluid, the elastic properties of the deformable part of the valve stem can deteriorate over time. This deterioration of elastic properties can eventually lead to a condition known as compression hardening, in which the valve seat assumes its deformed shape in its normal non-inclined position. In other words, the elastic part of the valve stem permanently assumes a deformed shape similar to the shape it would normally assume during the valve's open condition. Once compression hardening has occurred, the valve will not seal completely in the closed position, thus causing undesirable leakage of potentially harmful fluid, as mentioned above. It is therefore an object of the present invention to provide a valve assembly that will in part overcome the above disadvantage or offer the industry a useful choice. All references, including any patents or patent applications cited in this report, are incorporated herein by reference. No acknowledgment is made that any reference constitutes prior art. The discussion of references states what its authors assert, and the applicants reserve the right to... to challenge the accuracy and relevance of the documents cited. It should be clearly understood that, although several prior art publications are referred to herein, this reference does not constitute an acknowledgment that any of these documents forms part of the general knowledge in the art in any country. It is recognized that the term 'comprise' may, in varying jurisdictions, be assigned either an exclusive or an inclusive meaning. For the purposes of this report, and unless otherwise noted, the term 'comprise' shall have an inclusive meaning – that is, it shall be taken to mean an inclusion not only of the enumerated components to which it directly refers, but also of other unspecified components or elements. This logical rationale shall also be employed when the term 'constitute' or 'comprise' is used in relation to one or more steps of a method or process. Other aspects and advantages of the present invention will become apparent from the following description, which is presented by way of example only. EXPOSITION OF THE INVENTION Therefore, from a first perspective, the invention consists of a valve assembly comprising: a valve body comprising a valve seat surrounding a valve outlet, a valve stem having a head portion adapted to make contact and form a seal with the valve seat when the valve is in a closed condition, the valve stem having an elastically deformable portion which is deformed when the valve is in the open position, thereby obtaining a restoring force to incline the head portion in the direction of contact with the valve seat, and an additional propulsion device mounted between the valve body and the valve stem to impel the head portion in the direction of contact with the valve seat. Preferably, the valve stem comprises a substantially cylindrical portion having, at one end, the valve head portion and, at the other end, an enlarged portion that forms the elastically deformable portion. Preferably, the enlarged part is substantially shaped like a cup or hemispherical hemisphere. Preferably, the valve stem is hollow with one end closed at the head, and the additional protrusion device is mounted inside the valve stem. Preferably, the additional protrusion device comprises a spring device. Preferably, the spring device is a helical compression spring that has a valve body end with a larger diameter than the valve head end, so that the valve head end of the spring device fits inside the valve stem and contacts the closed end part, and the valve body end of the spring device contacts mounting devices inside the valve body. Alternatively, the spring device is a substantially cylindrical compression spring that has a smaller diameter than the inside diameter of the cylindrical portion of the valve stem, and the valve body includes a mounting device, onto which the plate is mounted, that supports the valve body end of the spring device. Preferably, the support plate comprises a circular disc having an angled edge on a lateral surface, the support plate also supporting the open end of the valve stem and including a central column on which the end of the valve body of the spring device is positioned. Preferably, the support plate has a diameter substantially equal to the outside diameter of the enlarged part of the valve stem, and an annular edge is presented on the valve stem side of the support plate, the annular edge having an outside diameter substantially equal to the inside diameter of the enlarged part, so that the enlarged part is supported on the outer edge of the support plate. Ideally, the annular edge has an outer surface that slopes outward. Preferably, the valve body comprises a top plate in which the valve outlet is installed and a support frame that suspends the support plate mounting device under the valve opening. Preferably, the supporting framework comprises at least three supporting columns extending in In a direction substantially perpendicular from the top plate, the distal ends of the adjacent support columns are connected by connecting elements that form the support device for the support plate. From a second perspective, the invention consists, in combination, of a fluid outlet orifice that includes the valve assembly according to the first aspect and a fluid conduit connector adapted for connection to the outlet orifice, wherein the outlet conduit connector includes a contact element that makes contact with the valve stem head and moves the valve to the open position. BRIEF DESCRIPTION OF THE DRAWINGS Other aspects of the present invention will become apparent from the following description, which is presented by way of example and with reference to the accompanying drawings, in which: Figure 1 is a partially cutaway perspective view showing the valve assembly according to the present invention in a closed condition; Figure 2 is a cross-sectional front elevation view showing the valve assembly of Figure 1 in a closed condition; Figure 3 is a front elevation view in cross-section showing the valve assembly of Figure 1 in an open condition; Figure 4 is a front elevation view in cross-section showing the valve assembly of Figure 1 in a closed condition once the compression hardening of the valve stem has taken effect; Figure 5 is a perspective view from below and from one side of the valve assembly of Figure 1, with the outlet fitting of the storage container, the spring and the support disc removed for clarity. BEST WAYS TO PRACTICE THE INVENTION The valve assembly according to the present invention is an improvement on the valve assembly described in the New Zealand patent application of the applicant of this application, No. 329181, the contents of which are incorporated herein by reference. With reference to the drawings and initially in particular to figures 1 and 2, an outlet port, 1, of the storage container includes a valve body, 2, and an outlet fitting, 3, of the storage container. The outlet fitting 3 of the storage container includes a substantially cylindrical outlet port mounting section, 4, and a flange portion, 5, which is heat-sealed, bonded or otherwise joined, molded or formed integrally with a storage container (not shown), which is adapted to contain a fluid. As mentioned earlier, the stored fluid may be corrosive, poisonous or generally hazardous and may be heated to an elevated temperature. Valve body 2 includes a substantially cylindrical wall section, 6, which fits tightly within the mounting section 4 of the outlet port of the fitting. • · · · • · · · · · »· ···· Outlet fitting 3. The cylindrical wall section 6 can be a tightening fitting within the outlet fitting 3, and coupled action contact aspects are presented on the corresponding surfaces of the two components, so as to ensure that a seal is established and that the valve body can be easily inserted into the outlet fitting, but that the removal of the valve body is relatively difficult. For example, as shown in the drawings, the outer surface of the cylindrical wall section 6 is provided with an upwardly enlarged annular rib, 7, and a sealing rib, 8, while the inner surface of the outlet port mounting section 4 is provided with grooves. I or corresponding mutually fitting cavities. Alternatively, the valve body 2 and the outlet fitting 3 of the storage container may be glued, heat-sealed or otherwise joined or even molded or formed in an integral manner. The valve body 2 and the outlet fitting 3 of the storage container are preferably molded from a plastic material, such as linear low-density polyethylene. The upper end of the valve body 2 is provided with a cylindrical outlet port fitting, 9, which is dimensioned to be housed within a corresponding fitting in an outlet conduit connector (not shown), which is screwed into place for connection to the outlet port 1 by means of the partial threaded projections 10. Manual tightening of the outlet conduit connector into the outlet port 1 is aided by the installation of a flange, 11, which extends ΦΦΦ ·· · φφ φφ φφφφ ·· φφφφ φφφφ φφφφ φ φ · • · φφφφ φφ φ φφφφ φ φ φ φφφφφφ φφ φφφφ φ starting from the outlet hole fitting 9 and which is equipped with indentations, 12, around its circumference, in order to improve the user's grip. Referring now to Figure 3, an end plate 12 partially closes the valve body 2, so that fluid does not flow through (i.e., into or out of) the outlet orifice fitting 9. A valve seat 13 is formed around a circular valve opening 26 in the end plate 12. The surface of the valve seat 13 is preferably substantially conical or generally tapered inwards, towards the center of the valve opening, and outwards, towards the outlet conduit connector side of the valve body. Suspended beneath the end plate 12 is a support frame, 14, upon which the valve mechanism (to be described shortly) is supported. The support frame is concentric with the valve opening 26 and the valve seat 13 and comprises at least three (four are shown) support elements or columns, 15, which project from the inner surface of the end plate 12 and are equally spaced from each other around the valve opening 26. For example, if three support columns were shown, they would then be spaced from each other in an equilateral triangle pattern. In the example shown, four support columns 15 are shown, each at the corner of a square. This is more clearly shown in Figure 5, which is a perspective view from below and from one side. The lower or distal ends of the columns Adjacent support columns 15 are connected by connecting elements 16. Consequently, rectangular windows are formed, limited on opposite sides by adjacent support columns 15, at the top by the end plate 12, and below by a connecting element 16. The windows allow fluid to flow easily through the support structure, which is preferably integrally molded with the valve body 2. A valve stem, 17, is installed within the valve body 10 to selectively close or allow fluid flow through the valve. The valve stem is made of an elastomeric material, such as, for example, an ethylene vinyl acetate copolymer (EVA), so that it is elastically deformable. The valve stem 17 includes a substantially cylindrical upper part, 18, and a substantially cup- or hemispherical lower part, 19. The substantially cylindrical upper part 18 of the valve stem has an annular valve face, 20, which has a conformation complementary to that of the valve seat. 13, in order to obtain a good seal when the valve assembly is in its closed condition. It can be seen in figure 3 that the valve assembly is in an open condition as the upper part of the valve stem has been moved downwards, thus separating the valve face 20 from the valve seat 13, so that fluid flow can flow through the valve opening 26. It can be seen that the valve stem 17 has a solid head section, 29, although much of the substantial cylindrical part 18 and the enlarged lower part 19 is open from below and, consequently, much of the valve stem is hollow. Since the valve stem is made of an elastically deformable material, the application of an external force to the head 29 of the valve stem will result in deformation of the valve stem at or around the junction between the cylindrical and enlarged parts (as shown in Figure 3). The central part of the valve seat therefore acts as a diaphragm, whereby the deformation of the valve stem allows the valve face 20 to disengage from the valve seat 13, so that fluid can pass through the valve opening 26. Since the valve stem is elastically deformable, its deformation provides a restoring force to the valve head, impelling the valve face into contact with the valve seat.In other words, the valve assembly is of the normally closed type. A circular support plate or disc, 21, is installed substantially parallel to the end plate 12, but supported on the connecting elements 16 of the support frame 14. In the embodiment shown, the disc 21 has a diameter substantially equal to the diagonal of the square formed by the support columns 15, so that segments of the disc are situated on and supported by the connecting elements 16. As can be seen in figures 2 to 4, the outer diameter of the enlarged part 19 of the valve stem 17 equals the diameter of the disc 21. To aid in positioning the lower end of the valve stem on the disc, an annular edge, 22, with an inclined outer edge can be installed on the upper surface of the disc. In order to allow the fluid inside the hollow valve stem to be evacuated during deformation, the disc is provided with a fluid flow orifice, 23. As mentioned above, the internal movements of the valve assembly are occasionally or permanently immersed in potentially corrosive fluid that may be at an elevated temperature. Under these conditions, the elastic properties of the valve seat may change and, over time, compression hardening may occur, so that in the valve closed condition (as shown in Figure 1), the valve seat may assume a deformed conformation as its non-inclined, normal configuration. Since the deformation of the valve seat reduces its effective length, this results in the displacement of the valve face away from the valve seat, allowing fluid to pass out of the valve opening 26 even when no external force is applied to the valve stem head. In order to overcome this difficulty, the valve assembly according to the present invention also includes an additional protrusion device, 24, between the disc 21 and the valve stem head 17. The additional protrusion device may be a spring device, such as, for example, a cylindrical helical compression spring, as shown in the drawings. The cylindrical spring may be held in position by mounting its lower end on a mounting device, such as, for example, the column 25, which projects from the upper surface of the disc 21 and by the fact that its upper end surrounds a circular projection from the lower side of the valve stem head. Alternatively, the spring device 24 may comprise a tapered helical compression spring having a base diameter larger than its tip diameter.The diameter of the base end of the tapered spring may be made to fit with the annular edge 22 of the disc 21 or may be equal to the inner diameter of the base of the enlarged part of the valve stem. Alternatively, the additional protrusion device may be any type of elastically deformable substance, provided it does not suffer from compression hardening. Figure 4 shows the valve assembly according to the present invention in its closed condition after the onset of compression hardening in the valve stem. It can be seen that the spring 24 is providing a supporting closing force to the restoring closing force usually applied by the elastically deformable valve stem, so that the valve opening 26 is sealed despite the valve seat having undergone a permanent change in its conformation. Furthermore, because of the presence of the additional protrusion device 24, continuous opening and closing cycles of the valve assembly will be possible while maintaining a fluid-impermeable seal at the valve opening every time the valve assumes its closed position. Finally, the valve stem... The valve can be replaced, but the present invention allows for the replacement to be delayed or avoided. It was found that, once compression hardening of the valve stem has occurred, only a small closing force is required to seal the valve opening 26 and it is therefore possible to employ a relatively small, low-cost helical spring as the additional spring device 24. Aspects of the present invention have been described by way of example only, and it should be understood that modifications and additions may be made to it without abandoning its scope, as defined in the appended claims. f

Claims

CLAIMS 1. Valve assembly, CHARACTERIZED by comprising: a valve body including a valve seat surrounding a valve outlet, a valve stem having a head portion adapted to contact and form a seal with the valve seat when the valve is in a closed condition, the valve stem having an elastically deformable portion that is deformed when the valve is in the open position, thereby obtaining a restoring force to incline the head portion in the direction of contact with the valve seat, and an additional propulsion device mounted between the valve body and the valve stem to impel the head portion in the direction of contact with the valve seat.

2. Valve assembly, according to claim 1, CHARACTERIZED in that the valve stem comprises a substantially cylindrical part having, at one end, the valve head part and, at the other end, an enlarged part forming the elastically deformable part.

3. Valve assembly according to claim 2, CHARACTERIZED in that the enlarged part has substantially a cup or hemispherical shape.

4. Valve assembly, according to any of the preceding claims, CHARACTERIZED in that the valve stem is hollow, with one end closed at the head part, and the additional protrusion device is mounted inside the valve stem.

5. Valve assembly, according to any of the preceding claims, CHARACTERIZED in that the additional propulsion device comprises a spring device.

6. Valve assembly, according to claim 5, CHARACTERIZED in that the spring device is a helical compression spring having a valve body end with a larger diameter than one end of the valve head, so that the valve head end of the spring device fits inside the valve stem and contacts the closed end part and the valve body end of the spring device contacts mounting devices inside the valve body.

7. Valve assembly according to claim 5, characterized in that the spring device is a substantially cylindrical helical compression spring having a diameter smaller than the inner diameter of the cylindrical part of the valve stem, and the valve body includes a mounting device, on which a support plate is mounted, which supports the valve body end of the spring device.

8. Valve assembly, according to claim 7, CHARACTERIZED in that the support plate comprises a circular disc that supports the open end of the valve stem and also includes a central column on which the valve body end of the spring device is positioned.

9. Valve assembly according to claim 7, CHARACTERIZED in that the valve stem 5 comprises a substantially cylindrical part having, at one end, the valve head part and, at the other end, an enlarged part forming the elastically deformable part, and the support plate has a diameter substantially equal to the outside diameter of the enlarged part. 10 of the valve stem, and an annular edge is provided on the valve stem side of the support plate, the annular edge having an outer diameter substantially equal to the diameter of the enlarged part, so that the enlarged part is supported on the outer edge of the support plate. 15 10. Valve assembly, according to claim 9, CHARACTERIZED in that the annular edge has an outer surface inclined outwards.

11. Valve assembly, according to any one of claims 7 to 10, CHARACTERIZED in that the valve body comprises an upper plate, on which the valve outlet is presented, and a support frame that suspends the mounting device of the support plate under the valve opening.

12. Valve assembly, according to claim 11, CHARACTERIZED in that the support plate comprises at least three support columns, which extend substantially perpendicularly from the top plate, the distal ends of the adjacent support columns being connected by connecting elements that form the support device for the support plate.

13. Fluid outlet orifice, which includes the valve assembly according to any of the preceding claims and an outlet conduit connector adapted for connection to the outlet orifice, CHARACTERIZED in that the outlet conduit connector includes a contact element that contacts the valve stem head and moves the valve to the open position.