GB1581004A - Valve assembly - Google Patents

Description

(54) VALVE ASSEMBLY (71) We, BESTOBELL VALVES LIMITED, a British company, of Greasbrough Road, Rotherham, South Yorkshire, S60 1RE, do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to valve assemblies comprising a housing having a valve seat surrounding a fluid passage; and a valve closure member which co-operabes with the seat, and in particular to improvements in the seal formed between the valve seat and the valve closure member when the closure member is in a closed position.

According to the invention, a valve assembly for controlling fluid flow comprises a housing having a valve seat surrounding a fluid passage; and a valve closure member which cooperates with the seat; the closure member including a first sealing surface which abuts a first face of the seat around the passage when the closure member is in a closed position, and a recess fitted with a flexible, resilient, annular sealing lip for sealing against a second face of the seat around the passage, the sealing lip being provided by a metal strip one annular edge of which is fixed to the closure member and the other annular edge of which abuts the second face of the seat when the closure member is in the closed position; the arrangement being such that, in use, when the closure member is in the dosed position any fluid from the upstream side which leaks between the first sealing surface and the first face of the seat will pass into the recess and urge the sealing lip against the second face of the seat.

The co-operation between the first sealing surface and the first face of the seat provides a coarse seal, and may also provide a stop to locate the closed position of the closure member; while the co-operation between the flexible sealing lip and the second face of the seat ensures that the seal is secure.

It is particularly convenient if the flexible sealing lip is arranged to flex as the closure member is brought to its closed position, to pre-stress the lip. Thus, even without leakage the sealing lip is urged against the second face of the seat when the closure member is in the closed position. The pre-stress may be enhanced by making the sealing lip substantially Sshaped in cross-section such that as the closure member is brought to the closed position, a convex part of the lip rides over an edge of the valve seat.

Preferably, the sealing lip is silver plated and at least the second face of the seal is highly polished in order to improve the seal between the lip and the second face of the seat.

Some examples of valve assemblies constructed according to the invention are illustrated in the accompanying drawings, in which: Figure 1 is an axial section through a globe valve; Figures 1A is an enlarged view of the flexible seal shown in Figure 1; Figure 2 is an axial section through a check valve; Figure 2A is an enlarged view of the flexible seal shown in Figure 2; Figure 3 is an axial section through a parallel slide valve; Figure 3A is an enlarged view of the flexible seal shown in Figure 3; Figure 4 is an axial section through a gate valve; Figure 4A is an enlarged view of the flexible seal shown in Figure 4; Figure 5 is an axial section through a wedge valve; Figure 5A is an enlarged view of the flexible seal shown in Figure 5; Figure 6 is an axial section through a safety valve; and Figure 6A is an. enlarged view of the flexible seal shown in Figure 6.

Each of the valve assemblies illustrated in the Figures. has a first housing 7 having a valve seat 8, a valve closure member 9, with a first sealing surface 10, and a recess 11, in the closure member 9 fitted with a flexible sealing lip 12. The sealing lip 12 may be made from stainless steel, and may be bonded or welded to the closure member 9.'The first sealing surface 10 of the closure member 9 co-operates with a first face 13 of the seat 8, while the flexible sealing lip 12 co-operates with a second face 14 of the seat 8.

The globe valve illustrated in Figure 1 has a handle 15 which is attached to a spindle 20, the spindle 20, the spindle having screw thread 21 towards the end remote from the handle. A second housing 7' is screwed into the, first housing 7 and has an internal screw thread 22 through which the spindle 20 is screwed. The spindle 20 also passes through a screw-on end cap 23 and a seal 24. When the valve is closed, by turning the handle 15 so that the spindle 20 is screwed down into the assembly, the closure member 9 is moved, without rotating with the spindle, by the spindle towards the seat 8 until the first sealing surface 10 abuts the first face 13.

In this closed position, a coarse seal is formed between the first sealing surface 10 and the first face 13 and fluid flow from port 17 to port 16 is substantially inhibited. Any fluid leaking past this coarse seal will ble trapped in the recess 11, and the sealng lip 12, which is pre-stressed by being formed in a substantially S-shape to abut the second sealing surface 14, will be further urged towards the surface 14 to form a fine seal. It should be noted that this valve is a uni-directional valve and that the fine seal would be ineffective for fluid flow from port 16 to port 17, since in that case the sealing lip 12 would be urged away from the surface 14.

The check valve shown in Figure 2 is designed, when in the closed position, to inhibit fluid flow from port 16 to port 17.

As in the previous example a coarse seal is formed between the first sealing surface 10 and the first face 13, and a fine seal is formed between the sealing lip 12 and the second sealing surface 14. This valve is also a uni-directional valve and the fine seal will not be effective for fluid flow from port 17 to port 16.

The check valve is not manually operable and the closure member 9 is maintained in the closed position under the force of gravity. Alterna'tively,' a spring may be positioned in the cavity 25 to act against the upper side of the base of the closure member 9 and the lower side of the cap 23.

The parallel slide valve illustrated in Figure 3 is manually- operable, and has a handle 15 fitted to a spindle 20, the spindle having an external screw thread 21 and an integral disc 27. A second housing 7' is screwed into the first housing 7 and the spindle 20 passes through an end cap 23 screwed to the second housing 7', and through a seal 24. The disc 27 is received in a groove 28 in the second housing 7', to prevent the spindle from moving longitudinally within the housing. The closure member 9 is hollow and has an internal screw thread 26 with which it is screwed onto the spindle 20.The closure member 9 is also arranged to be non-rotatable so that in turning the handle 15 in one direction the closure member will be drawn into the chamber 18 and the valve will be opened; and on turning the handle 15 in the opposite direction the closure member will be lowered across the fluid flow path to close the path.

In the illustrated closed position, the fine seal formed between the left hand sealing lip 12 and second sealing surface 14, will be ineffective to fluid flowing into the valve through port 16, and thus fluid may leak past the left hand coarse seal formed be tween the first sealing surface 10 and the first face 13 either into the chamber 18 or into the space 19 below the closure 'member 9. Fluid in chamber 18 or space 19 may further leak past the right hand coarse seal but will then be trapped in the recess 11 and will further urge the sealing lip 12 towards the second sealing surface 14.

Since the valve is exactly symmetrical it can also prohibit fluid flow from port 17 to port 16 in an exactly analogous manner.

As well as producing a pre-stress in the lip 12, the S-shape cross-section allows the lip to ride smoothly over the edge of the seat 8 which is also slightly chamferred, as, shown in Figure 3A.

The gate valve shown in Figure 4 is another uni-directional valve and will only prohibit fluid flow from port 16 to port 17. The closure member 9 is wedge shaped and is arranged to be non-rotatable with the spindle 20. The advantage of the wedge shape is that the further the closure member 9 is pushed down into the housing 7 the more effective will be the coarse seals formed between first sealing surfaces 10 and corresponding first faces 13. Fluid entering the valve through port 16 may leak past the left hand coarse seal either into chamber 18 or the space 19, as in the previous example, and may then also leak past the right hand coarse seal. However, it will then pass into recess 11 and further urge the lip 12 towards the sealing surface 14.

The sealing lip 12 is again S-shaped both for pre-stressing and to allow the lip to ride smoothly over the edge of the seat 8 as in the previous example. The construction and mode of operation of the rest of the valve is substantially the same as that described with reference to the globe valve illustrated in Figure 1.

The wedge valve shown in Figure 5 is effectively a combination of the bi-direc tional arrangement of the parallel slide valve illustrated in Figure 3 with the wedge shape of the closure member 9 illustrated in Figure 4, and operates in a similar way to the Figure 4 example.

Finally, Figure 6 illustrates a safety valve which is designed, under normal conditions, to prohibit fluid flow from port 16 to port 17 but which will open when fluid pressure increases above a certain value.

The spindle 20 is positioned within the up per portion of the housing 7 and has, at its lower end, an integral disc 29 which sub stantially fills the cross section of the upper part of the housing 7. Below the disc a reduced diameter portion 30 is received in the hollowed out closure member 9. The closure member 9 is biased towards the closed position by a spring 31 trapped between the upper face of the disc 29 and the lower face of an adjustable cap 23 screwed into the top of the housing 7. Thus by adjusting the position of cap 23 the fluid pressure at which the valve will open can be pre-set.

When the closure member 9 is in the closed position any fluid leaking past the coarse seal formed between the first sealing surface 10 and first face 13 will be trapped in recess 11 and, as in the previous examples, will further urge the seal ing lip 12 towards the second face 14.

In all these examples, the seat 8 may or may not be integral with the housing 7.

WHAT WE CLAIM IS: - 1. A valve assembly for controlling fluid flow, the assembly comprising a housing having a valve seat surrounding a fluid passage; and a valve closure member which cooperates with the seat; the closure member including a first sealing surface which abuts a first face of the seat around the passage when the closure member is in a closed position, and a recess fitted with a flexible, resilient, annular sealing lip for sealing against a second face of the seat around the passage, the sealing lip being provided by a metal strip one annular edge of which is fixed to the closure member and the other annular edge of which abuts the second face of the seat when the closure member is in the closed position; the arrangement being such that, in use, when the closure member is in the closed position any fluid from the upstream side which leaks between the first sealing surface and the first face of the seat will pass into the recess and urge the sealing lip against the second face of the seat.

2. A valve assembly according to claim 1, wherein the flexible sealing lip is arranged to flex as the closure member is brought to the closed position, to prestress the lip.

3. A valve assembly according to claim 2, wherein the pre-stress is lenhanced by making the sealing lip substantially Sshaped in cross-section such that as the closure member is brought to the closed position, a convex part of the lip rides over an edge of the valve seat.

4. A valve assembly according to any one of the preceding claims, wherein the sealing lip is silver plated and at least the second face of the seat is highly polished in order to improve the seal between the lip and the second face of the seat.

5. A valve assembly according to claim 1, substantially as described with reference to any one of the examples illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. urge the lip 12 towards the sealing surface 14. The sealing lip 12 is again S-shaped both for pre-stressing and to allow the lip to ride smoothly over the edge of the seat 8 as in the previous example. The construction and mode of operation of the rest of the valve is substantially the same as that described with reference to the globe valve illustrated in Figure 1. The wedge valve shown in Figure 5 is effectively a combination of the bi-direc tional arrangement of the parallel slide valve illustrated in Figure 3 with the wedge shape of the closure member 9 illustrated in Figure 4, and operates in a similar way to the Figure 4 example. Finally, Figure 6 illustrates a safety valve which is designed, under normal conditions, to prohibit fluid flow from port 16 to port 17 but which will open when fluid pressure increases above a certain value. The spindle 20 is positioned within the up per portion of the housing 7 and has, at its lower end, an integral disc 29 which sub stantially fills the cross section of the upper part of the housing 7. Below the disc a reduced diameter portion 30 is received in the hollowed out closure member 9. The closure member 9 is biased towards the closed position by a spring 31 trapped between the upper face of the disc 29 and the lower face of an adjustable cap 23 screwed into the top of the housing 7. Thus by adjusting the position of cap 23 the fluid pressure at which the valve will open can be pre-set. When the closure member 9 is in the closed position any fluid leaking past the coarse seal formed between the first sealing surface 10 and first face 13 will be trapped in recess 11 and, as in the previous examples, will further urge the seal ing lip 12 towards the second face 14. In all these examples, the seat 8 may or may not be integral with the housing 7. WHAT WE CLAIM IS: -

1. A valve assembly for controlling fluid flow, the assembly comprising a housing having a valve seat surrounding a fluid passage; and a valve closure member which cooperates with the seat; the closure member including a first sealing surface which abuts a first face of the seat around the passage when the closure member is in a closed position, and a recess fitted with a flexible, resilient, annular sealing lip for sealing against a second face of the seat around the passage, the sealing lip being provided by a metal strip one annular edge of which is fixed to the closure member and the other annular edge of which abuts the second face of the seat when the closure member is in the closed position; the arrangement being such that, in use, when the closure member is in the closed position any fluid from the upstream side which leaks between the first sealing surface and the first face of the seat will pass into the recess and urge the sealing lip against the second face of the seat.

2. A valve assembly according to claim 1, wherein the flexible sealing lip is arranged to flex as the closure member is brought to the closed position, to prestress the lip.

3. A valve assembly according to claim 2, wherein the pre-stress is lenhanced by making the sealing lip substantially Sshaped in cross-section such that as the closure member is brought to the closed position, a convex part of the lip rides over an edge of the valve seat.

4. A valve assembly according to any one of the preceding claims, wherein the sealing lip is silver plated and at least the second face of the seat is highly polished in order to improve the seal between the lip and the second face of the seat.

5. A valve assembly according to claim 1, substantially as described with reference to any one of the examples illustrated in the accompanying drawings.