GB2322430A

GB2322430A - Valve

Info

Publication number: GB2322430A
Application number: GB9701184A
Authority: GB
Inventors: Alan Henry Organ
Original assignee: Dowty Seals Ltd
Current assignee: Dowty Seals Ltd
Priority date: 1997-01-21
Filing date: 1997-01-21
Publication date: 1998-08-26
Also published as: GB9701184D0

Abstract

A valve, for example a butterfly valve, is designed such that sealing between the seat (6) and the valve member (20) occurs substantially simultaneously over the periphery of a sealing region. The valve member may curve towards and/or away from the valve seat and the valve seat may be suitably profiled. Each portion of the valve member may move substantially perpendicularly towards the corresponding portion of the valve seat as the valve member tends towards the closed condition. The valve member or valve seat may carry a resilient sealing member.

Description

VALVE The present invention relates to a valve, such as a butterfly valve.

Known butterfly valves, as illustrated in Figure 1 of the accompanying drawings, comprise a planar valve member 2 pivotally mounted for rotation about an axle 4. The valve member 2 is located inside a valve housing 6 having a profiled inner wall 8 such that the valve member 2 abuts a portion of the wall 8 to sealingly engage with it when the valve member is at a closed position. The valve illustrated in Figure 1 has a generally rectangular valve member 2. As a consequence, the valve member 2 must also seal with inwardly extending wall portions 10, illustrated by the chain line 10', at is peripheral edges above and below the plane of crosssection in Figure 1.

As shown in Figure 1, the distance between an inner edge 12 of the valve member 2 and the wall portion 10 increases with increasing radial distance from the axis of rotation 4.

Consequently, the ingress of particles to a radially inward position between the surface 12 and the wall 10 can cause the valve member to be held away from the closed state.

Furthermore a greater sealing force per unit length occurs at the radially innermost portions 14 that at the outermost edge portions 16.

According to the present invention, there is provided a valve comprising a valve member moveable to and from sealing engagement with a valve seat, in which the valve member and a cooperating sealing region of the seat are profiled such that contact between the valve member and the sealing region occurs substantially simultaneously over the entirety of the sealing region as the valve member moves to the closed position.

It is thus possible to provide a valve where the closing force and sealing action is uniformly distributed along a sealing region of the valve.

Preferably the valve is a butterfly valve. The valve member may be disposed towards a centre line of a fluid flow channel and rotatably mounted such that the valve member is movable to and from a position at which it closes the channel.

Preferably, the surface of the valve member, or at least the periphery thereof, has a curved profile. The valve member may curve, at least initially, towards the valve seat with increasing radial distance from the axis of rotation of the valve member. Thus, the valve member can be profiled to compensate for the increasing radial distance that is observed when the valve member and seat are planar.

Additionally or alternatively, the valve member may curve away from the valve seat with increasing radial distance, and the valve seat may be profiled in order to compensate for the increasing gap that will otherwise be generated.

Advantageously the valve member is arranged such that its motion as it tends towards the closed position causes each portion of the valve member to move substantially perpendicularly towards the corresponding portion of the valve seat.

A sealing face between the valve member and the valve seat may be offset from the surface of the valve member. Advantageously, at least one of the valve member and the valve seat carries a resiliently deformable sealing member. The sealing member may be formed of rubber or the like. The provision of a resiliently deformable sealing member ensures a substantially fluid tight seal. This, together with the design freedom to set the surface profile of the valve body or a selected portion thereof, enables the contact characteristic between the valve member and the valve seat to be controlled. The term "contact characteristic" refers to the sealing action and, more specifically, whether one part of the valve member tends to contact the valve seat before another part, and also refers to the distribution of the contact force around the region of contact between the valve member and the valve seat.

The sealing face of the valve member may have a peripheral rim formed thereon for supporting a sealing member, or for engaging a sealing member carried on or integral with the valve seat.

It is thus possible, by selecting a suitable valve member profile and offset to the sealing surface, to produce a valve in which the distance between a sealing surface of the valve seat and the portions of the valve member that engage the sealing surface is substantially uniform around the sealing surface as the valve member tends towards the closed position.

The present invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic illustration of a known butterfly valve; Figure 2 is a schematic cross-section through a butterfly valve constituting an embodiment of the present invention; Figure 3 is a cross-section through the central portion of a valve member in a butterfly valve constituting a second embodiment of the present invention; and Figure 4 is a cross-section through the peripheral portion of the valve element shown in Figure 3.

In each of the valves shown in Figures 2 to 4, a butterfly valve member 20 is arranged to engage and seal a substantially rectangular orifice, although it is to be understood that the present invention is not limited to valves having a rectangular orifice, but is applicable to other shapes as well.

Figure 2 is a cross-section through a butterfly valve comprising a butterfly valve member 20 mounted for rotation about an axis 22. The valve member 20 is illustrated at the closed position. The sealing surfaces 24 of the valve member 20 are defined by convex surfaces which blend into nonsealing regions 26 of the valve member. In a central portion of the valve, the only region of contact between the valve member 20 and a valve seat 6 contained in a housing, is at peripheral regions 28. However, the end portions (i.e.

edges of the valve member 20 above and below the plane of the page) also seal with side wall portions 30 of the seat 6.

Thus, at the edges of the valve member, the entirety of sealing surface makes contact with the valve seat, ie. portion 6 and sidewalls 30. End portions 32 of the valve member 20 act to prevent the passage of fluid past the interface between the side walls of the seat housing and the valve member.

Figure 3 schematically illustrates a valve member constituting a further embodiment of the present invention. The sealing surfaces 40 of the valve member 38 extend increasing forwardly with increasing radial distance from the axis of rotation of the valve member 38. That is, region 42 of the valve member 38 is located slightly further to the right (as shown in Figure 3) than the more radially inward region 44 of the uppermost sealing face of the butterfly member 38. The valve seat (not shown) has a corresponding profile along portions which engage with the peripheral regions of the valve member. The valve member illustrated in Figure 3, like that in Figure 2, is rotated anticlockwise from the position shown to open the valve, and rotated clockwise to the position shown close the valve. The central portions of the valve member may have a recess 46 formed therein in order that the sealing portions of the valve member stand proud of the rest of the valve member surface. The valve member 38 further carries curved portions 50 which extend from the radially outermost edges of the valve member 38, in order to form a shallow V-shaped surface 52 for supporting a resilient sealing member 54, as illustrated in Figure 4. The sealing member 54 also extends along the end portions of the valve member, as indicated by designation 54'.

It is thus possible to provide a butterfly valve in which a uniform seal is formed around the periphery of the valve member.

Claims

1. A valve comprising a valve member moveable to and from sealing engagement with a valve seat, in which the valve member and a co-operating sealing region of the seat are profiled such that contact between the valve member and the sealing region occurs substantially simultaneously over the entirety of the sealing region as the valve member moves to the closed position.

2. A valve as claimed in claim 1, in which the valve is a butterfly valve.

3. A valve as claimed in claim 1 or claim 2 in which the valve member is disposed towards a centre line of a fluid flow channel, and is moveable to and from a position at which it closes a fluid flow channel.

4. A valve as claimed in any preceding claim in which the valve member is rotatably mounted.

5. A valve as claimed in any preceding claim in which at least the periphery of the surface of the valve member has curved profile.

6. A valve as claimed in claim 5 in which at least an initial portion of the curved profile is curved towards the valve seat.

7. A valve as claimed in claim 5 or 6 in which the profile of the valve member curves towards the valve seat with an increasing radial distance from the axis of rotation of the valve member.

8. A valve as claimed in any one of claims 1 to 6 in which the valve member curves away from the valve seat with increasing radial distance.

9. A valve as claimed in claim 8 in which the valve seat is profiled to compensate for the increase in depth caused by curvature away from the valve seat.

10. A valve as claimed in any preceding claim in which the valve member is arranged such that movement of the valve member towards the closed position causes each portion of the valve member to move substantially perpendicularly towards the corresponding portion of the valve seat.

11. A valve as claimed in any preceding claim in which there is a sealing face between the valve member and the valve seat and which the sealing face is offset from the surface of the valve member.

12. A valve as claimed in any preceding claim in which at least one of the valve member and the valve seat carries a resiliently deformable sealing member.

13. A valve as claimed in claim 12 in which the sealing member is formed of rubber or other suitable material.

14. A valve as claimed in an preceding claim in which the valve member has a peripheral rim for supporting a sealing member.

15. A valve member as claimed in any one of claims 1 to 13, in which the valve member has a peripheral rim for engaging with a sealing member carried on or integral with the valve seat.

16. A valve substantially as hereinbefore described with reference to and as illustrated by Figure 2 of the accompanying drawings.

17. A valve substantially as hereinbefore described with reference to and as illustrated by Figures 3 and 4 of the appending drawings.