GB1572389A

GB1572389A - Valves

Info

Publication number: GB1572389A
Application number: GB2093378A
Authority: GB
Original assignee: Donkin and Co Ltd
Current assignee: Donkin and Co Ltd
Priority date: 1978-05-20
Filing date: 1978-05-20
Publication date: 1980-07-30

Description

(54) IMPROVEMENTS IN OR RELATING TO VALVES (71) We, BRYAN DONKIN COM PANY LIMITED, a British Company of Derby Road, Chesterfield, 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 present invention relates to valves and particularly to valve sealing means for inter alia, rotary ball valves and slide valves.

For example, in conventional rotary ball valves, it is usual to employ two fixed valve seats which are made of a plastics material and compressed around the ball valve member during valve construction to provide an intimate sealing contact therewith.

However, owing to the inherent characteristics of plastics materials, the valve seats tend to creep and the seal between the ball and the seat becomes ineffective causing valve leakage. Such valve seats are also particularly susceptible to leakage after the ball valve member has been left in a partly oPen position and caused indentation of the plastics valve seat. Scoring or scratching of the valve seat by grit or abrasive particles present in the fluid passing through the valve can also cause leakage.

The object of the present invention is to provide or substantially mitigate the aforesaid leakage problems.

According to the present invention there is provided a valve comprising a valve body defining a passageway through which fluid may flow and having a valve seat co-operable with a valve member which is movable with respect to the seat to open and close the passageway, the seat defining a groove provided with flexible retaining lips from between which a first resilient sealing member projects to seal against the valve member in at least the valve-closed position thereof.

The present invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a longitudinal sectional view through a rotary ball valve according to the present invention; Figure 2 is a view to an enlarged scale of part of Figure 1; and Figure 3 is a longitudinal sectional view of part of a slide valve according to the present invention.

Figure 1 shows a rotary ball valve comprising a valve body 1 defining a passageway 2 for fluid through flow and a rotary ball valve member 3 which is retained in the passageway 2 between two annular valve seats 4 and 5.

The rotary ball member 3 is substantially spherical in shape and is provided with a passageway 6 through which fluid can flow when the valve is open. The member 3 is keyed as at 7 to a valve spindle 8 which can be rotated, via a cap 9 attached thereto, to turn the member 3 between an open position, wherein the passageway 6 is aligned with the longitudinal axis of the passageway 2 in the valve body, and a closed position, wherein the passageway 6 lies normal to the axis of the passageway 2. In both the open and closed position of the ball member 3, the valve seats 4 and 5 provide an intimate sealing contact with the member 3, as will be described to prevent flow of fluid around the member 3 rather than through it.

The valve seats 4 and 5 are made of a deformable plastics material, such as polytetra fluoroethylene (PTFE) or nylon, and are maintained under compression in sealing contact against the valve member 3 by inserts 10 and 11 respectively. The inserts 10 and 11 each comprise an annular member which is screwed into the passageway 2 to retain and provide a fixed abutment for the valve seat 4 and 5 respectively. Each insert 10, 11 defines a substantially frusto-conical passageway 12, 13 respectively for the fluid, which passageway tapers inwardly towards the valve member 3.

To ensure that a seal is maintained between the valve seats 4 and 5 and the valve member 3, even at low fluid pressures, a Belville type disc spring 14 is interposed between the valve seat 5 and the insert 11, a washer 15 being additionally provided between the seat 5 and the Belville spring 14 against which the latter bears to prevent uneven deformation of the seat 5. In this way, the valve member 3 is tightly gripped by the valve seats 4 and 5 with a predetermined pressure according to the load characteristic of the washer 14.

Referring now particularly to Figure 2, each valve seat 4, 5 comprises an annular member which is in perpetual contact with the spherical valve member 3 and the valve body 1. To provide an effective seal with the valve body 1, an annular groove 16 is formed in each seat 4, 5 which groove 16 locates and retains an elastomeric O-ring 17 in sealing contact with the body 1. To seal against the valve member 3, however, each seat 4, 5 is compressed, as described above, so that a surface 18 thereof conforms in shape to the surface of the member 3. Additionally, to provide an effective seal, each seat 4, 5 is provided with a groove 19 in which is inserted a second elastomeric O-ring 20. The G-ring 20 projects out of the groove 19 between two flexible lips 21, which retain the ring 20 within the groove 19, and provides a resilient line seal against the valve member 3.

The sealing means desc-ioed -2ed above may also be employed in a slide valve, such as is shown in Figure 3, which illustrates a valve seating arrangement of a plate type parallel slide valve. The valve comprises a body 22 which defines a passageway 23 through which fluid can flow when the valve is open.

A valve member comprising a slidable plate 24 is mounted in the valve body 22 whereby a port 25 in the plate 24 can be made to register with the passageway 23 to open the valve, as shown in Figure 3. Sealing means 26, similar to that which is described above with reference to Figures 1 and 2, are mounted under compression on each side of the plate 24 in grooves 27 in the body 22 whereby a pair of elastomeric O-rings 28 each project out of a groove 29 formed in a plastics seat 30 between two flexible lips 31 integrally formed with the seat 30. The valve body 22 is additionally provided with grooves 32 adjacent the valve seats 30 in each of which grooves 32 is located an elastomeric O-ring 33.In this way, the seats 30 themselves seal against the plate 24 via their lips 31, the 0nngs 28 additionally seal between the seats 30 and the plate 24,and the O-rings 33 seal between the seats 30 and the body 22.

In both embodiments described above the O-rings 20, 28 can be made of any resilient elastomeric material such as rubber. In use of the valves, fluid pressure acts on the lips 21, 31, which in turn bear against the valve member 3 or plate 24 respectively to provide a pressure assisted seal. The lips 21, or 31 also ensure positive retention of the ring 20, or 28 for all practical operating conditions. Additionally, the resilient nature of the O-ring 20, or 28 permits them to deform to give a preload to the sealing surface 18 or 34 of the valve sets 4, 5 or 30 to provide an effective seal even at low fluid pressure.Further, the O-ring 20 or 28 provides a sensitive line seal which is effective even when the valve seat 4, 5 or 30 has been deformed by indentation or damaged by scratching or scoring and which has a squeegee action to remove dirt and other particles from the surface of the valve member 3 or plate 24 when it is moved.

Thus, it will be appreciated that the valves described above are each provided with three independent seals at each side of the valve member 3 or the plate 24, namely the O-rings 19 or 33, O-rings 20 or 28, and the lips 21 or 31. Any one of these six seals is capable of providing a bubble tight closure of the valve independently of the other five.

Although in the above description, the 0rings 20 and 28 are described as having been inserted into the grooves 19 and 29 of the valve seats 4, 5 and 30, it is also possible to injection mould the seats 4, 5 and 30 around the O-rings 20 and 28. In this case, the seats 4, 5 and 30 can be made of a plastics material such as nylon and the O-rings 20 and 28 of an elastomeric material such as rubber as described above. In this process, the grooves 19 and 29, and lips 21 and 31 would be formed, albeit with a slightly different shape from that shown in the drawings, by the fit of the plastic around the O-ring.

WHAT WE CLAIM IS: 1. A valve comprising a valve body defining a passageway through which fluid may flow and having a valve seat co-operable with a valve member which is movable with respect to the seat to open and close the passageway, the seat defining a groove provided with flexible retaining lips from between which a first resilient sealing member projects to seal against the valve member in at least the valveclosed position thereof.

2. A valve as claimed in claim 1, in which fluid pressure can act on the flexible retaining lips which in turn bear against the resilient sealing member to provide a pressure assisted seal against the valve member.

3. A valve as claimed in claim 1 or 2, in which the valve seat comprises an annular member of flexible plastics material.

4. A valve as claimed in any of claims 1 to 3, in which the resilient sealing member comprises an elastomeric O-ring.

5. A valve as claimed in any of claims 1 to 4, in which the valve seat defines a second groove in which is located a second resilient

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. member 3. To ensure that a seal is maintained between the valve seats 4 and 5 and the valve member 3, even at low fluid pressures, a Belville type disc spring 14 is interposed between the valve seat 5 and the insert 11, a washer 15 being additionally provided between the seat 5 and the Belville spring 14 against which the latter bears to prevent uneven deformation of the seat 5. In this way, the valve member 3 is tightly gripped by the valve seats 4 and 5 with a predetermined pressure according to the load characteristic of the washer 14. Referring now particularly to Figure 2, each valve seat 4, 5 comprises an annular member which is in perpetual contact with the spherical valve member 3 and the valve body 1. To provide an effective seal with the valve body 1, an annular groove 16 is formed in each seat 4, 5 which groove 16 locates and retains an elastomeric O-ring 17 in sealing contact with the body 1. To seal against the valve member 3, however, each seat 4, 5 is compressed, as described above, so that a surface 18 thereof conforms in shape to the surface of the member 3. Additionally, to provide an effective seal, each seat 4, 5 is provided with a groove 19 in which is inserted a second elastomeric O-ring 20. The G-ring 20 projects out of the groove 19 between two flexible lips 21, which retain the ring 20 within the groove 19, and provides a resilient line seal against the valve member 3. The sealing means desc-ioed -2ed above may also be employed in a slide valve, such as is shown in Figure 3, which illustrates a valve seating arrangement of a plate type parallel slide valve. The valve comprises a body 22 which defines a passageway 23 through which fluid can flow when the valve is open. A valve member comprising a slidable plate 24 is mounted in the valve body 22 whereby a port 25 in the plate 24 can be made to register with the passageway 23 to open the valve, as shown in Figure 3. Sealing means 26, similar to that which is described above with reference to Figures 1 and 2, are mounted under compression on each side of the plate 24 in grooves 27 in the body 22 whereby a pair of elastomeric O-rings 28 each project out of a groove 29 formed in a plastics seat 30 between two flexible lips 31 integrally formed with the seat 30. The valve body 22 is additionally provided with grooves 32 adjacent the valve seats 30 in each of which grooves 32 is located an elastomeric O-ring 33.In this way, the seats 30 themselves seal against the plate 24 via their lips 31, the 0nngs 28 additionally seal between the seats 30 and the plate 24,and the O-rings 33 seal between the seats 30 and the body 22. In both embodiments described above the O-rings 20, 28 can be made of any resilient elastomeric material such as rubber. In use of the valves, fluid pressure acts on the lips 21, 31, which in turn bear against the valve member 3 or plate 24 respectively to provide a pressure assisted seal. The lips 21, or 31 also ensure positive retention of the ring 20, or 28 for all practical operating conditions. Additionally, the resilient nature of the O-ring 20, or 28 permits them to deform to give a preload to the sealing surface 18 or 34 of the valve sets 4, 5 or 30 to provide an effective seal even at low fluid pressure.Further, the O-ring 20 or 28 provides a sensitive line seal which is effective even when the valve seat 4, 5 or 30 has been deformed by indentation or damaged by scratching or scoring and which has a squeegee action to remove dirt and other particles from the surface of the valve member 3 or plate 24 when it is moved. Thus, it will be appreciated that the valves described above are each provided with three independent seals at each side of the valve member 3 or the plate 24, namely the O-rings 19 or 33, O-rings 20 or 28, and the lips 21 or 31. Any one of these six seals is capable of providing a bubble tight closure of the valve independently of the other five. Although in the above description, the 0rings 20 and 28 are described as having been inserted into the grooves 19 and 29 of the valve seats 4, 5 and 30, it is also possible to injection mould the seats 4, 5 and 30 around the O-rings 20 and 28. In this case, the seats 4, 5 and 30 can be made of a plastics material such as nylon and the O-rings 20 and 28 of an elastomeric material such as rubber as described above. In this process, the grooves 19 and 29, and lips 21 and 31 would be formed, albeit with a slightly different shape from that shown in the drawings, by the fit of the plastic around the O-ring. WHAT WE CLAIM IS:

1. A valve comprising a valve body defining a passageway through which fluid may flow and having a valve seat co-operable with a valve member which is movable with respect to the seat to open and close the passageway, the seat defining a groove provided with flexible retaining lips from between which a first resilient sealing member projects to seal against the valve member in at least the valveclosed position thereof.

sealing member to seal against the valve body.

6. A valve as claimed in any of claims 3 to 5, in which the valve seat is maintained under compression in sealing contact against the valve member in at least the valve closed position thereof.

7. A valve as claimed in any of claims 1 to 6, in which the valve member comprises a rotary ball member located between and cooperable with two similar valve seats.

8. A valve as claimed in claim 7 when dependent on claim 3, in which the valve seats are maintained under compression in perpetual sealing contact with the rotary ball valve member.

9. A valve as claimed in claim 8, in which the first resilient sealing members of the valve seats are maintained in perpetual sealing contact with the ball valve member.

10. A valve as claimed in any of claims 1 to 6, in which the valve member comprises a slidable plate located between and co-operable with two similar valve seats.

11. A valve substantially as hereinbefore described with reference to Figures 1 and 2 or Figure 3 of the accompanying drawings.