GB2182118A

GB2182118A - A butterfly valve

Info

Publication number: GB2182118A
Application number: GB08621188A
Authority: GB
Inventors: Friedrich Geiser
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-09-24
Filing date: 1986-09-02
Publication date: 1987-05-07
Also published as: JPH0233908B2; JPS6275179A; GB2182118B; FR2587781A1; DE3533937C1; CH672668A5; GB8621188D0; FR2587781B1

Abstract

A butterfly valve has a housing (1) with a spherically shaped sealing surface (40) and a closure member (4) rotatable and pivotable therein by means of an actuating rod (13) preferably with a guide slot (35). The closure member (4) comprises a support member (5), which is connected to the actuating rod (13) and which is mounted in the housing (1) via a universal joint (8, 9). On its front side the support member (5) is connected by pin(s) (18) to an elastically deformable valve disc (12) in the form of a flat dish with a base (14) and a rim (15) and preferably a sealing strip (16), which rim is directed towards the support member (5). The valve disc (12) is normally spaced from the support member (5) and is supported marginally relative thereto eg. by an annular bead (17). With the valve closed, a differential pressure, irrespective of which side of the closure member (4) it acts on, acts so as to augment the closing pressure. The fluid tightness of the closed valve is thus assured independently of the direction of action of the differential pressure. <IMAGE>

Description

SPECIFICATION A butterfly valve The invention relates to a butterfly valve.

Patent Specification GB 1585210 (Cupedo's) discloses a butterfly valve having a housing with a bore and a sealing surface, a closure memberwhich is rotatably and pivotally mounted therein, an actuator having a rod, a support stem which is provided on the rear side of the closure member and projects beyond the rim of the latter, its end being universally mounted in the housing and, diametrically opposite thereto, the closure member is connected to the rod of the actuator, actuation of the rod causing the closure memberto rotate and pivot from an open position to a closed position againstthesealing surface ofthe housing and vice versa, the axis of rotation oftheclosure member lying outside the plane thereof.

This valve, because of its specific design is suitable for sealing relative to one another the chambers to be separated from each other bythe closure member, in that the closure member is firmly pressed on the sealing surface by means of the actuator. The construction enables the valve to be opened or closed irrespective of whether or not an overpressure or a differential pressure prevails between the chambers separated by the closure member and also irrespective of from which direction any such differential pressure acts against the closure member.Certainly, such a differential pressure acting againstthe closure memberofthe closed valve has the effect that the closing pressure applied via the actuator is either increased or decreased according to the side from which this differential pressure acts on the closure member. In one case the differential pressure acts on that side ofthe closure member on which the support stem is mounted and to which the rod of the actuator is connected. In this case the closing pressure is augmented by the acting differential pressure. In another case the differential pressure acts on the opposite side of the closure member and endeavours to lift it from the sealing surface.The closing pressure is thereby reduced and the fluidtightness of the closed shut-off valve may be impaired, if not entirely eliminated.Avalve ofthis type has a sealing strip of a plastic or elastomeric material, so that the closing pressure cannot be set too high with the result that variations in the closing pressure have a not insignificant effect on fluidtight ness.

Patent Specification US 4052036 (Schertler) dis closes a valve in which overpressure directed in the opposite direction to the sealing pressure at the seat causes deflection of the sealing plate in the manner of a lever arm to increase the sealing pressure on the seat packing. However, the valve disclosed is a gate valve and has constructional requirements quite dif ferent to those of a butterfly valve.

Patent Specification DE(ALS) 1057407 (Garrett) discloses a butterfly valve having a closure member which comprises a circular support member and a circularvalve disc. The support member has a flat side and a rounded periphery. The valve disc is dished and has a flanged over rim which extends around the periphery of the support member. Over presssure in one direction will flatten the disc against the flat side ofthe support member and will radially expand the disc causing the periphery of the valve disco engage the bore ofthe housing. The greater the over pressure, the greater the sealing effect. This valve will only seal with an over pressure acting in only one direction.

Patent Specification US 3008685 (Rudden) discloses a butterfly valve with a closure member comprising a support member and a dished valve disc.

This valve is similar in principle to that shown in DE (ALS) 1057407. in addition, however, there is a further valve controlling the pressure in the chamber formed by the support member and the valve disc.

Patent Specification US 3077332 (Burtis) also discloses a butterfly valve. The closure member is a plain circular rotatable disc. The housing has an an nular recess with resilient metal rings located in the recess, of which one is the valve seat. When the valve is closed, the disc engages the metal valve seat. With an over pressure acting in one direction, the valve seat is subject to bending forces augmenting the sealing pressure. With an over pressure acting in the opposite direction, the sealing pressure is reduced and leakage may occur.

The subject ofthe invention is a butterfly valve in which the closing pressure exerted via the actuator is always augmented if an over pressure or a differential pressure is acting on the closure member, irrespective ofthe side from which this differential pressure acts on the closure member, so that the fluidtightness ofthe valve is independent of the direction of action of the differential pressure.

In one aspect the invention provides a butterfly valve having a housing with a bore and a sealing surface, a closure member which is rotatably and pivotally mounted therein, an actuator having a rod, a support stem which is provided on the rear side of the closure member and projects beyond the rim of the latter and carries at its end a joint ball universally mounted in the housing and, diametrically opposite thereto, the closure member is connected to the rod of the actuator, actuation of the rod causing the closure memberto rotate and pivot from an open position to a closed position against the sealing surface of the housing and vice versa, the axis of rotation of the closure member lying outside the plane thereof, wherein the closure member has a support member which on its rear side carries the support stem, is connected with the actuator and, on its front side, carries a valve disc; the valve disc has a rim which is directed towards the support member and on which is disposed a sealing strip co-operating fluidtightlywith the spherically shaped sealing surface of the housing when the vaive is closed; the valve disc, inside its rim and near to the edge of its bottom, abuts against one or more marginal projections of the support member; the valve disc is designed to be elastically deformable to a greater extent than the support member when subjected to the same load; the valve disc is spaced from the support member apart from its contact with the marginal projections, and at least one pin is secured to the valve disband passes with clearance through a respective bore in the support member.

This combination offeatures has a successful outcomewhich is surprising even to the person skilled in the art. The valve can be opened under any prevailing pressure and any differential pressure presentalways increases the closing pressure, irrespective of its particular direction of action on the closure member.

In another aspect the invention provides a butterfly valve comprising a housing having a bore and a sealing surface, a closure memberwhich is supported in the housing for pivotal and rotatable movement, and an actuating rod which is arranged to act on the closure member to cause movement ofthe closure member between a first position, in which the closure member seats on the sealing surface and the valve is closed, an intermediate second position, and a third position, in which the valve is open, movement between the first and second positions being pivotal movement about a first axis lying outside of the closure member and movement between the second and third positions being rotatable movement about a second axis intersecting the first axis and also lying outside the closure member, wherein the closure member comprises a support member and an elastically bendable valve disc carried by the support member, the valve disc comprises a circular plate and a divergently outwardly extending rim and the support member supports the disc inwardly of the periphery ofthe plate, such that a differential pressure always augments the pressure of the closure member on the sealing surface in the closed position.

An embodiment ofthe invention will now be described by way of example, reference being made to the accompanying drawings, of which: Figure 1 shows a part of a valve in cross-section, with the closure member in an intermediate position; Figure2 shows the valve with the closure member in the closed position; Figure 3 shows the valve with the closure member in the closed position and under differential pressure loading from the left; and Figure 4shows, partly in section, a view ofthe valve with the closure member in the open position.

The illustrated butterfly valve has a housing 1 with athrough-bore 2 which tapers towards one flange side 3 of the housing 1 to form a spherically shaped sealing surface 40. A closure member4 is pivotally and rotatably mounted in the housing 1.

The closure member4 comprises a support member Sin the form of athick-walled circular plate.

Asupportstem 6 is welded to the rearside7 ofthe support member and projects laterally beyond the rim ofthe closure member4and at its free end car ries a joint ball 8. This support stem 6 is situated in a diametral plane ofthe closure member 4. The joint ball 8 is universally accommodated in a joint socket9 which, in turn, is situated in a cylindrical recess 10 of the housing 1 extending through the wall thereof.

Aguide pin 36 is mounted diametrically opposite to the support stem 6 on the rear side 7 ofthe support memberS by means of a bearing block 11; the guide pin axis lies parallel to the plane ofthe support member Sand passes transversely through a guide slot 35 provided at the end portion of the actuating rod 13 which projects into the housing 1 and is connected to an actuator. The arrangement is such that the imaginary centre axis of the actuating rod 13 passes through the centre of the joint ball 8, this im aginarylineformingan axisofrotation29forthe closure member4.

The closure member4 has a valve disc 12 on the front side ofthe support member 5. The valve disc 12 is in the shape of a flat dish with a flat bottom 14and a rim 15 in the shape ofthesurface of a frustum of a cone, on the outside of which there is provided a sealing strip 16, for example of plastics material. Aseal- ing strip can be provided on the spherical surface 40 ofthe housing 1 instead of or in addition to the strip 16. The valve disc 12 is thin-walled in relation to the support member Sand therefore under the action of an equal load is elastically deformableto a considerably greater extent than the support member 5.The supportmember5 has on its rim an annular bead 17 which projects from the front side of the support member 5 and against which the valve disc 12 abuts freely; otherwise, however, the valve disc 12 is gene rally spaced apart to a small extent from this support member 5. The arrangement is such that the bead 17 lies near to the edge of the flat bottom 14 of the valve disc 12. Screw-threaded pins 18 are connected with the valve disc 12 and extend with clearance through bores 19 in the support member5. Nuts 20 are screwed onto the pins 18 and connect the support member 5 and valve disc 12 to form the closure member 4.

The actuating rod 13 is displaced longitudinally during operation ofthe shut-off valve. This is carried out manually, by such known means as a motor drive or a hydraulic or pneumatispiston-cylinder unit, not illustrated in detail. The guide slot 35 on the inner end ofthe actuating rod 13 extends generally helically so that - starting from the open position shown in Figure4-when the actuating rod 13is pushed into the housing 1 the closure member4 is firstly rotated about axis 29 into the position shown in Figure 1 and is subsequently pivotted and pressed into its sealing position shown in Figu re 2 about an axis extending through the joint ball 8 and intersecting the axis 29.In this case the guide pin 36 is firstly rotated about an axis, which lies at right angles to its longitudinal extent and parallel to the axis of rotation 29, and is subsequently displaced transverselyto itself. The actuating rod 13 is thus secured against rotation. Because the pins 18 are mounted with clearance, the valve disc 12 can thus conform readily and automatically to the spherical sealing surface 40.

Referring now to Figure 2, the sealing force required for a tight seal is applied via the guide slot 35 in association with the actuating rod 13. Assuming now that the closed valve is loaded with a differential pressure acting from the right,this over pressure tends to expand the rim 15, whereby the sealing strip 16 is pressed harder against the spherical sealing surface 40, so augmenting the sealing force applied via the actuating rod 13.

If the differential pressure acts on the closed valve from the left in the drawings, because oftheforce previaling directly on the valve disc 12, the bottom 14 ofthe valve disc 12 is slightly pressed in or dished, as a result of its marginal support bythe bead 17, and is deformed in the manner shown in Figure 3. The rim 15 of the valve disc 12 is thereby pressed outwards and the sealing force is thus also increased.

Although, in the foregoing, the su pport mem ber 5 has been illustrated and described as a plate-like structure, it may instead be of an annular design, in which case this annuluswill be of a size rendering it appropriately resistant to bending. Irrespective of whetherthe support member 5 is designed as a plate or ring, instead of an annular bead 17, boss or rib-like projections spaced peripherally apart fro one another can be used. The face ofthe support member5, facing the valve disc 12, can be flat over its entire extent and the marginal support element or elements can be provided on the inside ofthe valve disc 12; for example an annular depression could be impressed on the front side of the valve disc 12 at the edge ofthe bottom 14 and inside the rim 15to provide an annular projection.

The closure member4 can be articulated via a lever in a manner of hinge on the end portion ofthe actuating rod 13 projecting into the housing 1 and the actuating rod 13, during its actuation, can be displaced not only axiaily but also rotated about its axis.

Guide slots may also be used for this purpose, which are preferably then disposed inside the actuator.

Claims

1. A butterfly valve having a housing with a bore and a sealing surface, a closure memberwhich is rotatably and pivotally mounted therein, an actuator having a rod, a support stem which is provided on therearsideoftheclosurememberand projects beyond the rim of the latter, its end being universally mounted in the housing and, diametrically opposite thereto, the closure member is connected to the rod of the actuator, actuation ofthe rod causing the closure memberto rotate and pivot from an open position to a closed position against the sealing surface of the housing and vice versa, the axis of rotation ofthe closure member lying outside the plane thereof, wherein the closure member has a support member which on its rear side carries the support stem, is connected with the actuator and, on its front side, carries a valve disc; the valve disc has a rim which is directed towards the support member and on which is disposed a sealing strip co-operating fluidtightly with the spherically shaped sealing surface of the housing when the valve is closed; the valve disc, inside its rim and neartotheedgeofits bottom, abuts against one or more marginal projections of the support member; the valve disc is designed to be elastically deformable to a greater ex tent than the support memberwhen subjected to the same load; the valve disc is spaced from the support member apart from its contact with the marginal projections, and at least one pin is secured to the valve disc and passes with clearance through a respective bore in the support member.

2. Avalveaccordingto Claim 1,wherein the mar- ginal projection is a peripherallyannularbead.

3. Ashut-offvalve according to Claim 1 wherein a plurality of pins are secured on the valve disc, each of which is situated on the front side of the support member nearerthe marginal projections serving as supports forthe valve disc.

4. Ashut-offvalve according to Claim 1,wherein the rim of the valve disc is shaped in the manner of the surface of a frustum of a cone.

5. A butterfly valve comprising a housing having a bore and sealing surface, a closure member which is supported in the housing for pivotal and rotatable movement, and an actuating rod which is arranged to act on the closure member to cause movement of the closure member between a first position, in which the closure member seats on the sealing surface and the valve is closed, an intermediate second position, and a third position, in which the valve is open, movement between the first and second positions being pivotal movement about a first axis lying outside of the closure member and movement between the second and third positions being rotatable movementabouta second axis intersectingthefirst axis and also lying outside the closure member, wherein the closure member comprises a support member and an elastically bendable valve dise car- ried by the support mem ber, the valve dise com- prises a circular plate and a divergently outwardly extending rim and the support member supports the disc inwardly of the periphery ofthe plate, such that a differential pressure always augments the pressure of the closure member on the sealing surface in the closed position.

6. Avalve substantially as herein described with reference to and as shown in the accompanying drawings.