GB2092714A

GB2092714A - Seal rings for use in disc valves

Info

Publication number: GB2092714A
Application number: GB8111410A
Authority: GB
Original assignee: ADAMS ARATUREN N APPARATE Gebr
Current assignee: ADAMS ARATUREN N APPARATE Gebr
Priority date: 1978-03-10
Filing date: 1979-02-19
Publication date: 1982-08-18
Also published as: CA1100119A; MX153721A; ES253796Y; GB2016114B; GB2092714B; ES253796U; IN151668B; AU529903B2; BR7901408A; ES482475A1; GB2016114A; AU4343579A; AR216373A1

Abstract

A seal ring for a disc valve has an annular base (40) and a sealing member (66) supported on and spaced radially inwardly from the base (40) by a web (70). The sealing member has an inwardly facing sealing surface (50) for engaging the seating surface (48) of a valve disc (8), and as the valve closes, the web deflects resiliently to enhance the seal therebetween. <IMAGE>

Description

1 GB 2 092 714 A 1

SPECIFICATION

Improved disc valve seal ring The present invention relates to a seal ring for use with disc or butterfly type valves in which a disc is pivotally disposed within a conduit of the valve defined by a generally cylindrical housing for pivotal movement of the disc between an open position, in which it is generally parallel to an axis of the valve, and a closed position in which the disc is generally perpendicular to the valve axis. The seal ring of the present invention has particular use in disc valves of the type described and claimed in our copending Application No: 79 05748 (Serial No: 2,016, 114) to which reference is directed.

The present invention seeks to provide a seal ring for use in disc valves of the above type, which enhances the formation of a seal between the sealing surface of the ring and a complementary seating surface on the valve disc of the valve. To this end, the invention provides a seal ring for use with disc valves having a seating surface for sealingly engaging a sealing surface of the seal ring, which seal ring comprises an annular base having a width in a radial direction and a thickness 9C in an axial direction; a sealing member radially inwardly spaced from the base and defining a radially facing annular sealing surface for engaging the seating surface of a said disc valve; and a web formed in a resilient material and interconnecting the base and the sealing member, the web extending substantially radially between the base and the sealing member and having a thickness in an axial direction which is substantially less than said thickness of the base, the web being deflectable in use in response to increased pressure between the sealing surface and the seating surface of a said disc valve to enhance the sea[ made thereby. 40 In preferred embodiments of the invention the sealing surface has a convexly curved crosssectional profile which is typically of an arcuate configuration. It is also preferred that the seal ring includes means for causing the deformation of the member 110 and the web along a generally circular path, and wherein the circular path and the arcuately shaped sealing surface have centres which lie on a straight line that intersects a theoretical contact point between the sealing surface and the seating surface of a said disc valve. The radius of curvature of the circular path is normally less than that of the arcuate profile of the sealing surface, the ratio between them typically being at least 1.5. The straight line is preferably substantially perpendicular to the tangent to the arcuate profile at the theoretical contact point, as is the web preferably substantially perpendicular to the tangent to the arcuate profile at the theoretical contact point.

A disc valve incorporating a seal ring according to the invention will now be described by way of example with reference to the accompanying drawings wherein:- Figure 1 is a side elevational view, in section, of the valve and shows, in dotted lines, the valve disc in its open position; Figure 2 is a fragmentary, simplified side elevational view, in section, and illustrates the geometric relationships of the valve housing, the seal ring and the valve disc; Figure 3 is an enlarged, fragmentary, side elevational view which illustrates the sealing arrangement in greater detail; and Figure 4 is an enlarged, side elevational view in section, illustrating in detail the seal ring crosssection and the deflection of the seal ring under axially acting forces.

Referring first to Figure 1, a valve 2 constructed in accordance with the present invention generally comprises a valve housing 4 which includes a conduit 6 that extends through the housing. A valve disc 8 is disposed within the conduit and pivotally mounted thereto with a shaft 10 that is suitably journalled in the valve housing and that defines a pivot axis 12 for the disc for pivotally moving the disc between its open position, shown in dotted lines, in which the disc is generally parallel to a valve axis 14 and a closed position in which the disc is generally perpendicular to the valve axis as is more fully described hereinafter.

The conduit 6 includes a cylindrical section 16 which extends from a first end 18 of the housing towards a second end 20, an inwardly protruding, tapered section 22 which is disposed intermediate the housing ends, and a second cylindrical conduit section 24 of an enlarged outer diameter that terminates at the second housing end.

An annular recess is formed in the inwardly protruding section 22 of the housing, its radially outermost extent is defined by a cylindrical wall 28. A clamping ring 30 is positioned within the second cylindrical wall 28. A clamping ring 30 is positioned within the second cylindrical conduit section 24 and it is secured to the housing with a plurality of axially oriented bolts 32. Preferably, the clamping ring has a slanted inner wall 34 which slopes from the second housing end towards the annular recess 26 and which has an innermost diameter approximately equal to the innermost diameter of the protruding housing section 22. Thus, annular recess together with the portion of clamping ring 30 that extends beyond the cylindrical wall 28 define a radially inwardly open, annular groove 36 in the housing.

Disposed within groove 36 is a seal ring 38 which is constructed as is further described below. It has a base 40 that terminates in a radially outermost, cylindrical wall 42 of a diameter less than the diameter of groove wall 28 so that the seal ring can be adjusted in radial directions within the confines of the groove. For instances in which the seal ring is constructed of a metal or similar material, a gasket ring 44 may be placed between the seal ring base and the inwardly protruding section 22 of the housing so as to prevent the leakage of fluid therebetween when the disc is in its closed position and one or the other side of the 2 GB 2 092 714 A 2 disc is pressurized.

The operation of valve 2 illustrated in Figure 1 can now be briefly summarized. When the valve is to be closed, a valve actuator (not separately shown) coupled to shaft 10 is energized to pivotally move disc 8 about axis 12 in a counterclockwise direction, as indicated by corresponding arrows in Figure 1, from the open position (shown in dotted lines) into the closed position in which the disc is oriented transverse to valve axis 14. In the closed position a sealing plane 46 defined by the theoretical line of contact between a seating surface 48 of the disc and a sealing surface 50 of the seal ring is perpendicular to the valve axis. To open the valve, the actuator is energized to pivot the disc in Figure 1, in the opposite direction until it is again substantially parallel to the valve axis.

Referring now to Figure 2, the detailed construction, position and cooperation of seating surface 48 of disc 8 and sealing surface 50 of seal ring 38 are described. The seating surface 48 of disc 8 has a conical shape and it is selected so that when the disc is in the closed position, the apex "A" of the (seating surface) cone 52 (shown in dotted lines) is on valve axis 14 and the axis "X" of the cone is coaxial, that is coincides with valve axis 14. Further, the disc is given an excess thickness "T" (measured parallel to cone axis "X") and disc end faces 54, 56 are slanted by an angle 11 a" of between 1 to 101 and preferably of no more than about 50 relative to a plane which is perpendicular to the housing axis -V.

The end faces 54, 56 of the disc are normally substantially parallel with respect to each other and they are slanted so that slant angle "a" lies in a plane that includes cone axis "X" and is perpendicular to pivot axis 12. Further, the slant angle is chosen so that the end faces slope away from the (counterclockwise) pivotal closing movement of the disc as is clearly illustrated in Figure 2 to avoid a premature contact between the disc and the seal ring. Such premature contact would take place if the end faces were perpendicular to cone axis "X" as is indicated in Figure 2 in dotted lines and identified with reference numerals 54' and 56', respectively.

If the end faces were not so slanted, the end faces and the seating surfaces 48 would meet at (imaginary) leading edges 58 and 60 (during movement of the disc from the open to the closed position in a counterclockwise direction). Since the distance from disc pivot axis 12 to imaginary leading edges 58, 60 is greater than the distance from the pivot axis to the intersection points 62 between sealing plane 46 and seating surface 48 (or sealing surface 50), the leading edges would contact the sealing surface before the disc is in its closed position. To avoid such contact and potential damage to the seal ring, the disc faces 54, 56 are slanted as above described to thereby in effect form recesses in perpendicular disc faces 541, 56' which avoid such premature contact. Moreover, the transition between the end faces and the seating surface is curved as is illustrated as a further precaution against such premature contact.

To facilitate and simplify the further discussion of the application herein, and to simplify claim terminology, the orientation of the slant angle "a" as above described will hereinafter be sometimes referred to as a slant---angletrailing the closing motion of the disc- or as a -trailing slant angle---.

The detailed construction of seal ring 38 is set forth later on. In its broadest form, however, it may have any cross-sectional profile so as at least a portion of its sealing surface 50 at the intersection 62 between the sealing surface and the sealing plane 46 has the same conical shape as the conical shape of seating surface 48 of disc 8 at these points. In a preferred embodiment of the invention, such conically shaped portion is defined by a curved sealing surface which, at point 62, has a tangent that defines over the full circular extent of the seal ring a tangent cone. The tangent cone is the same cone as the cone of which seating surface 48 is a part. Further, the tangent cone has the same orientation as the cone of the seating surface when the disc is in its closed position.

Thus, the tangent cone, like the cone defined by the seating surface has an apex -A- on valve axis 14 and a cone axis 'X' which is coaxial with the valve axis.

It should also be noted that the seating surface 48 of disc 8 and the sealing surface 50 of seal ring 38 are constructed and arranged so when the disc is in its closed position sealing plane 46 intersects the conical seating surface but is otherwise immediately adjacent the (proximate) end face 54 (upper half of disc in Figure 2) and 56 (lower disc half) and the curved transition between the respective end faces and the seating surface. Thus, there is an additional width of seating surface, identified with reference numeral 64, which is available for contacting the sealing surface of the seal ring. In other words, the seating surface is given an additional width thickness over what is theoretically necessary to establish a seal. By slanting the end faces in the above-discussed manner the additional width is provided without correspondingly increasing the thickness of the disc (to '71. The additional seating surface width 64 allows one to increase the contact pressure between the disc and the seal ring as is more fully described below.

Referring now to Figures 3 and 4, the construction of seal ring 38 and its cooperation with valve disc 8 are described in detail. Generally speaking, the seal ring may have a variety of cross-sections, for example, it may have the crosssection shown in Figure 2, and its seal rings surface 50 may have varying configurations so long as it defines the above-described conically shaped sealing surface at least at the intersection between the sealing surface and the sealing plane 46. Therefore, the sealing surface may, for example, have a conical shape complementary to that of seating surface 48. One aspect of the present invention, however, contemplates to give the sealing surface in cross-section, a convex, 1 1 3 GB 2 092 714 A 3 arcuately curved shape. Furthermore, the sealing surface is defined by a sealing member 66 of the sea[ ring which is deflectable under axially acting pressure.

Structurally, the cross-section of the seal ring comprises the above mentioned generally rectangular sea[ ring base 40 which has a width and a thickness so that the base is compressed in seal ring groove 36 when clamping ring 30 is tightened to prevent the leakage of fluid between the seal ring base and the valve housing 4. If a gasket 44 is used the thickness of the base is such that it slightly exceeds the distance between the opposing faces of the gasket and the clamping ring.

Joined to the base is a generally radially inwardly extending web 70 which has a thickness (in the axial direction) substantially less than the thickness of the base so as to render the web relatively flexible. Further, the web is slanted so that it is generally perpendicular to the tangent at the intersection between seal ring surface 50 and sealing plane 46. Expressed in other words, the web is perpendicular to seating surface 48 of the disc when the disc is in its closed position. Lastly, in cross-section the sealing member 66 extends generally perpendicular to the web to either side thereof, somewhat akin to the flange of an I-beam, for example.

Particularly for high temperature applications the seal ring is constructed of a resiliently deformable metal such as steel, stainless steel, berylium copper or the like. For such applications it is necessary to provide gasket 44 to prevent fluid leakage past the base. For lower temperature 100 applications, say for applications in which the maximum temperature does not exceed 1501C the seal ring may also be constructed of an elastomeric material such as plastic, rubber or the like of the desired hardness. In such instances, it is 105 normally not necessary to provide a separate gasket 44 since the tightened clamping ring 30 provides sufficient pressure between the seal ring base and the housing to prevent fluid leakage past them. In both instances the base, the web and the 110 sealing member are preferably integrally constructed.

The radial width of base 40 is selected so that the intersection between the (imaginary) extension of its radially inwardly facing, cylindrical surface 72 with a centre line 74 of the web (which is perpendicular to the conical seating surface at point 62) defines a centre of deflection 76 for sealing member 66 and web 70 that is spaced from sealing point 62 a distance "r". Further, sealing surface 50 is convexly arcuately shaped about a centre point 78 which lies on a straight line extension of web centre line 74 and which is spaced from sealing point 62 a distance "R" which is greater than 'Y', preferably by a factor of 125 at least about 1.5:1.

The seat ring 38 constructed as above described assures that the contact pressure generated at sealing point 62 between disc seating surface 48 and ring sealing surface 50 can130 be increased by moving the disc beyond its closed position. The contact pressure further increases as a function of the pressure differential that may act on the seal ring when the disc is closed whether the pressure differential acts from one side or the other of the seal ring. This results from the fact that the relatively thin and, therefore, flexible web is connected to the rigidly clamped seal ring base 40 so that an axial force component will swing the web and, therewith the sealing member 66 approximately above a circular path which is centred at point 76.

Thus, if pressure P, acts from the left, as illustrated in Figure 4, disc 8 is closed and the opposite side is at a lower pressure, say at atmospheric pressure, the forces applied against the lefthand side of sealing member 66 and web 70 force the two to the right along a generally circular path having its centre at point 76 and into the position shown in Figure 4 in dotted lines and identified with the reference numeral 80. Since the radius of curvature "R" of sealing surface 50 is greater than the swing radius -r- of the sealing member, a lefthand portion 82 (as seen in Figure 4) of sealing surface 50 moves radially inward as is indicated by the dotted lines in Figure 4. In actuality such a radial movement of the sealing member is prevented by the closed disc 8; instead, the sealing member and the web are moved slightly to the right and resiliently compressed, thereby correspondingly increasing the contact pressure between seating surface 48 and sealing surface 50 as a function of the magnitude of the pressure differential sides generated by P, Accordingly, the greater the pressure differential, which normally increases the danger of a resulting leak between the seal ring and the valve disc, the greater is the contact pressure between the two, thereby preventing such leaks and assuring that the valve of the present invention maintains a complete seal irrespective of the pressure which is must seal off.

If the pressure differential acts from the right of the seal ring as seen in Figure 4 by virtue of a fluid pressure P, which exceeds the pressure on the lefthand side of the ring, the same result is obtained. The pressure differential causes sealing member 66 and web 70 to swing to the left about point 76 into the position indicated by reference numeral 84. By virtue of the above described relationship between "R" and "r" the righthand portion of sealing surface 50 is theoretically moved radially inward as is indicated at 86. Since the disc blocks a radially inward motion, the contact pressure between the seal ring and the disc is again increased in the above described manner- Lastly, the contact pressure between the disc and the seal ring can be increased by pivotally moving disc 8 about pivot axis 12 beyond its closed position, that is beyond the position in which cone axis -X- of the conically shaped sealing surface 48 is coaxial with valve axis 14, so that the apex 'W' of the cone would fall below the valve axis and below point "A" as viewed in Figure 4 GB 2 092 714 A 4 2. This is accomplished by selecting the conical shape of seating surface 48 relative to the position of pivot axis 12 so that the distance from the pivot axis to the sealing point 62 (when the valve is in its normal, theoretically closed position) is less than the distance from the pivot axis to any of the points on the remaining width 64 of the seating surface, such as points 88 (Figures 2 to 4) and 90 (Figure 2). If this condition is met, movement of the disc beyond its closed position will resiliently compress sealing member 66 and web 70, thereby increasing the contact pressure. Such movement of the disc beyond its closed position may be accompanied by a slight resilient deflection of the sealing member and the web in the direction in which the disc moves, thereby swinging the two about point 76 to the right (as seen in Figure 4) which causes an additional increase in the contact pressure.

In presently preferred embodiments of the invention with an offset between pivot axis 12 and valve axis 14 of between 1 to 5 mm, a cone angle b" (Figure 2) in the range of between about 201 to 701 has yielded good results although under given circumstances the angle may exceed the stated range so long as the above condition is satisfied. For many applications the optimal angle is in the vicinity of about 400 and generally it can be observed that smaller diameter valves will have larger cone angles and vice versa because of the relative position of shaft axis 12 and, in the case of larger diameter valves, the need for limiting the thickness of the valve disc. Thus, in one example, a valve of a nominal valve diameter of 300 mm may have a cone angle "b" of approximately 34 while a valve of a nominal valve diameter of 600 mm may have a cone angle "b" of approximately 251, the valves having an eccentricity between the 100 valve aAs and the pivot axis of 2 and 3 mm, respectively.

Claims

1. A seal ring for use with disc valves having a seating surface for sealingly engaging a sealing surface of the seal ring, which sea[ ring comprises an annular base having a width in a radial direction and a thickness in an axial direction; a sealing member radially inwardly spaced from the base and defining a radially facing annular sealing surface for engaging the seating surface of a said disc valve; and a web formed in a resilient material and interconnecting the base and the sealing member, the web extending substantially radially between the base and the sealing member and having a thickness in an axial direction which is substantially less than said thickness of the base, the web being deflectable in use in response to increased pressure between the sealing surface and the seating surface of a said disc valve to enhance the seal made thereby.

2. A sea[ ring according to Claim 1 wherein the sealing surface has a convexly curved cross sectional profile.

3. A sea] ring according to Claim 2 wherein the profile of the sealing surface has a convexly arcuate configuration.

4. A seal ring according to any preceding Claim wherein the seal ring includes means for causing the deformation of the member and the web along a generally circular path, and wherein the circular path and the arcuately shaped sealing surface have centres which lie on a straight line that intersects a theoretical contact point between the sealing surface and the seating surface of a said disc valve. 75

5. A seal ring according to Claim 4 wherein the radius of curvature of the circular path is smaller than the radius of curvature of the arcuate profile of the sealing surface.

6. A seal ring according to Claim 5 wherein the radius of curvature of the arcuate profile is at least 1.5 times the radius of curvature of the circular path.

7. A seal ring according to any of Claims 4 to 6 wherein the straight line is perpendicular to the tangent to the arcuate profile at the theoretical contact point.

8. A seal ring according to any of Claims 4 to 7 wherein the web is substantially perpendicular to the tangent to the arcuate profile at the theoretical contact point.

9. A seal ring for use with disc valves according to Claim 1 and substantially as described herein with reference to the accompanying drawings.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1982. Published by the Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.

9. A seal ring for use with disc valves substantially as described herein with reference to the accompanying drawings.

New claims or amendments to claims filed on 20th April 1982.

Superseded claims 1-9.

New or amended claims:- 1. A seal ring for use with disc valves having a seating surface for sealingly engaging a sealing surface of the seal ring, which seal ring comprises an annular base having a width in a radial direction and a thickness in an axial direction; a sealing member radially inwardly spaced from the base and defining a radially facing annular sealing surface having, in cross-section, a convexly arcuate profile of a radius - R- for engaging the seating surface of a said disc valve; and a web formed in a resilient material and interconnecting the base and the sealing member, the web extending generally radially between the base and the sealing member and having a thickness in an axial direction which is substantially less than said thickness of the base, the member and the web means deforming relative to the base along a generally circular path of a radius "r" when an axially acting force is applied; and wherein "R" is greater than -r- and the circular path is arranged so that the force with which the sealing surface is biased against a said seating surface is enhanced when the axially acting force is applied.

2. A seal ring according to Claim 1 wherein the circular path and the arcuately shaped sealing surface have centres which lie on a straight line that intersects a theoretical contact point between the sealing surface and the seating surface.

3. A seal ring according to Claim 2 wherein the straight line is perpendicular to the tangent to the GB 2 092 714 A 5 arcuate profile at the theoretical contact point.

4. A seal ring according to Claim 2 or Claim 3 wherein the web is substantially perpendicular to the tangent to the arcuate profile at the theoretical 5 contact point.

5. A seal ring according to any preceding Claim wherein "R" is at least 1. 5 times---r-.

6. A seal ring according to any preceding Claim wherein the base forms the radially outermost 10 portion of the seal ring.

7. A sea[ ring according to any preceding Claim wherein the sealing surface faces in a substantially radially inward direction.

8. A seal ring according to any preceding Claim wherein the base, the web and the sealing member are integrally constructed.