GB2071820A - Seal assembly - Google Patents

Abstract

A bi-directional valve eg a butterfly valve has a sealing means 30 comprising an integral seat ring 31 and a resilient back-up means 30. The seat ring 31 includes an outer portion 32, an offset hinged L- shaped portion 33 having a cavity therein to position said back-up means 50, and a substantially rectangular inner portion 34 having a shoulder ring portion 35, 37 on each side thereof. Pressurization of said sealing means results in substantially perpendicular application of forces of said back-up means and the fluid pressure onto a closure means (21, Figs. 1 and 3-5, not shown). <IMAGE>

Description

SPECIFICATION Seal assembly This invention relates to bi-directional valves, and in particular to a new sealing means construction having applications in butterfly valves. Butterfly valves have many advantages over other types of valves in fluid flow regulation, most notable being lower cost to the manufacturer, quickness of opening and low restriction to fluid flow when fully open. However, these valves generally have been limited to low pressure applications because of their inability to seal tightly at high pressures. In some prior art valves, the seals are located in grooves in the valve body which often become dislodged when the valve is open thereby permitting fluid to flow around the seal.In other prior art valves, high pressure fluid may leak through the valve by flowing between the valve body and seal; while in many other prior art valves, contact between the disc and seal must be made so tight in order to prevent leakage that opening the valve, particularly large diameter valves, requires a large torque. Furthermore, in several prior art valves used in high pressure and/or high temperature applications, the seat ring or sealing means loses the desired preloading on the seat ring sealing face as the seat ring expands. In stili other floating seal valves, high pressure fluid, which enters the recess when the valve is closed, cannot escape when the valve is opened, thus causing the seal to blow out.

In other floating seat valves, an attempt is made to reduce the torque required to open and close the disc, while improving the retention of the seat ring sealing face as the seat ring expands by employing indirect or partial application of resilient means and fluid pressure forces on the sealing face.

It is an objet of the present invention to provides improved bi-directional valve which will neither leak nor blow out under high pressures and which is operable with a relatively low torque.

A further object of this invention is to provide a reliable, exceptional long life, relatively inexpensive and easily replaceable and serviceable valve seat.

It is still a further object of this invention to provide a bi-directional valve having improved sealing means which fully utilizes direct application of resilient means and fluid pressure forces on the sealing face.

The bi-directional valve herein is comprised of a valve body having a flow passage therethrough with a recess in proximity to the passage having a planar surface thereon. A retaining ring detachably affixed to the valve body also has a recess therein. The recesses form a chamber open to the passage having an axial centerline parallel to the planar surface of the valve body. The retaining ring is adapted to secure a sealing means in the valve body. A closure means, pivotally positioned in the passage and having a peripheral land, is adapted to engage a sealing means.

The sealing means comprises a novel structure of seat ring and resilient back-up means.

The seat ring includes an outer portion, a substantially rectangular inner portion having a shoulder ring extending on both sides thereof, and an offset hinged L-shaped portion integrally connecting the outer and inner portion. The L-shaped portion has a cavity therein adapted to receive a resilient back-up means, whereby in the presence of fluid pressure acting on said sealing means from either side thereof an improved dynamically loaded fluid leak-tight seal is established between said sealing means and the peripheral land of the closure means which results in the substantially perpendicular application of the resilient back-up means and fluid pressure forces on the peripheral land.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a plan view, in section, of a butterfly valve utilizing the seal of this invention with the closure means shown in solid lines in the closed position, and in broken lines in the open position.

Figure 2 is an enlargement of the seal of Fig. 1 with the seal unloaded. Such a condition would occur when the valve is open permitting fluid flow through the valve.

Figure 3 is an enlargement of the seal of Fig. 1 with the seal in a preloaded condition.

Such a condition would occur when the closure means is closed and no line pressure is applied.

Figure 4 is an enlargement of the seal of Fig. 1 with the seal in a preloaded and pressurized condition. Such a condition would occur when the closure means is closed and pressure differential across the valve forces line fluid into the channel on one side of the sealing means.

Figure 5 is an enlargement of the seal of Fig. 1 with the seal in a preloaded and pressurized condition. Such a condition would occur when the closure means is closed and pressure differential across the valve forces line fluid into the channel on the other side of the sealing means.

DESCRIPTION OF THE PREFERRED EMBODI MENTS Referring to the drawings and more particularly to Fig. 1, a valve, generally represented by reference numeral 10, having a flow passage 1 2 in valve body 14 is shown located in conduit 1 8. Valve 10 may be secured in the conduit by welding, bolted flanges, or other common way. A valve closure means, such as valve disc 21 having curvilinear peripheral land 22 is shown in solid lines in the closed position and in broken lines in the open position.Disc 21 is secured to stem 16 which protrudes through valve body 14 and has a handle or other means (not shown) attached thereto in the usual manner to provide an axis about which disc 21 may be rotated to open or close the flow passage 1 2. Sealing means 30 includes seat ring 31 and resilient back-up means, such as spring 50, and is disposed between valve body 14 and retaining ring 40 which is detachably connected to valve body 14 via fasteners 42, as shown. Since the axis of rotation of disc 21 does not coincide with a centerline through seat ring 31, there is eccentric movement of the disc relative to the seat ring causing a faster break-away between disc 21 and seat ring 31 than would otherwise result if the disc and seat ring centerlines coincided.However, the subject invention may be practiced with coincidence of the disc axis of rotation and the seat ring centerline.

Referring to Fig. 2, valve body 14 has a recess therein formed by planar surfaces 72 and 72A which are separated by first groove 76 therebetween, and second groove 78 which is adjacent surface 72. Retaining ring 40 has a recess therein comprising surfaces 82 and 82A disposed in juxtaposition to surfaces 72 and 72A, respectively, and separated by groove 86 therebetween, first surface 88 continuous of surface 82 in a plane normal thereto, and confining surface 89 continuous of surface 88 in a plane substantially normal thereto.

The aforementioned recesses of valve body 14 and retaining ring 40 define chamber 60 which is adapted to receive sealing means 30.

It should be noted that chamber 60 is so disposed that its axial centerline is positioned parallel to planar surface 72 of valve body 14.

Sealing means 30 is comprised of seat ring 31, made of heat and chemically resistant material such as fluorocarbon, urethane or elastomeric polymers, and resilient back-up means, such as a metallic garter-type spring 50. Seat ring 31 includes integrally connected outer portion 32, hinged L-shaped portion 33, and inner portion 34. When the disc is in open position and with retaining ring 40 secured to valve body 14, outer portion 32 is sized, preferably, so as to be fixedly retained in place in an area defined by second groove 78 and confining surface 89. The volume of mass of outer portion 32 is sized larger than the volume of material that can be contained between second groove 78 and confining surface 89, so that, the outer portion becomes compressed therein forming a fluid leak-tight seal around its periphery.To assure fixed retention of the outer portion therein, the area is, preferably, configurated to have narrowest extent along line AA' formed by joining the points of contact of surface 88 to confining surface 89 and of planar surface 72 to second groove 78. Though this embodiment is preferred, outer portion 32 can be of any suitable configuration and retained by any suitable means.

Portion 33, integrally joined to outer portion 32, contains cavity 55 therein, which is adapted to receive spring 50 which exerts counter or supportive forces to structure in contact thereto, to prevent the collapse of portion 33 when pressure differential is exerted on the retaining ring side of seat ring 31. Portion 33 is freely suspended from portion 32 in chamber 60, so that, pressure differential being exerted on either side of seat ring 31 causes hinge-like movement of portions 33 and 34 about line AA'. Portion 33 has surface 91 thereon, which is, preferably, of cut back or chamfered configurition thereby permitting a greater unoccupied portion of chamber 60, thus assuring unimpeded hinge-like movement of portions 33 and 34 about line AA'.Portion 33, though resilient and flexible, is of non-conical L-shaped configuration which upon loading via fluid pressure assumes a radii arc shape.

Inner portion 34, integral to portion 33, is substantially of rectangular shape, in section, having sealing surface 36. Inner portion 34 has integral shoulder ring portions 35 and 37 which project into grooves 86, 76, respectively, for controlling the amount of projection of seat ring 31 into passage 12, and preventing blow out of seat ring 31 when disc 21 is opened or closed. Sealing surface 36 may be spherical, conical or other similar shape, and portions 35 and 37 are, preferably, of trapezoidal configuration, in section. Since chamber 60 is wider than portions 33 and 34, channels 100, 101 are provided between portions 33, 34 and the recesses of ring 40 and valve body 14, respectively, facilitating insertion of seat ring 31 into chamber 60, pressurization and depressurization of cavity 55 and freedom of movement of portions 33 and 34 during valve operation.

Referring to Fig. 3, in its closed, unpressurized condition, disc 21 wedges land 22 into sealing surface 36 causing it to expand outwardly creating interference load 110. Channels 100 and 101 are approximately of equal width.

In Fig. 4, fluid under pressure is directed into channel 100. Fluid pressure component 1 20 acts normally on portions 33 and 34 causing their pivotal movement about line AA'. Spring 50, while acting to prevent the collapse of portion 33, moves with portion 33 until fully compressed against planar surface 72. The movement of portions 33 and 34 results in radial enlargement of channel 100, and abutting engagement of inner portion 34 and shoulder ring portion 37 with surface 72A and groove 76, respectively, preventing further displacement of inner portion 34.

Fluid pressure component 1 22 acts radially on portion 33 forcing it and spring 50 downward, transmitting through inner portion 34 directly onto sealing surface 36. Due to the parallel relationship of planar surface 72 and centerline LC of chamber 60, full fluid pressure component 1 22 and undeflected spring force component 51 is exerted directly onto surface 36. An improved dynamic loading of sealing surface 36 is provided by the direct applications of these forces and interference load 110 thereon resulting in substantially perpendicular application of these forces onto land 22.

In Fig. 5, fluid under pressure is directed into channel 101. Fluid pressure component 30 acts normally on inner portion 34, and cavity 55 of portion 33 causing pivotal movement of portions 33 and 34 about line AA', radial enlargement of channel 101, and engagement of surface 91 with the recess of ring 48. Inner portion 34 and shoulder ring portion 35 are in abutting engagement with surface 82A and groove 86, respectfully.

Fluid pressure component 1 30 can be broken down for purposes of explanation, into partial force components 56, 57 and 58.

Surfaces 82, 88 act as constraints for portion 33 under the loads of partial force components 56, 58, respectfully. Partial force components 57, as well as undeflected spring force component 51, is transmitted through inner portion 34 directly onto surface 36, providing by their direct applications and interference load 110, an improved dynamic loading ot surface 36 resulting in substantially perpendicular application of these forces onto larid 22.

Although a certain embodiment has been described and illustrated, modification may be made herein, as by adding, combining or subdi-vidin3 parts or by substituting equivalents or by applying the invention to other types of valves or mechanisms while retaining advantages and benefits of the invention, which itself is defined in the following claims.

Claims (7)

CLAIM-S

1. A bi-directional valve comprising: A. a valve body having a flow passage therethrough with a recess in proximity to the passage, the recess having a planar surface with a groove therein; B. a retaining ring surrounding the passage and detachably affixed to said valve body and having a recess therein, the recess having a surface with a groove therein; C. a chamber open to the passage and formed between the recesses, said chamber having an axial centerline parallel to the planar surface; D. a closure means pivotally positioned in the passage between an open and a closed position to allow or prevent, respectively, fluid flow therethrough, said closure means having a peripheral land adapted to engage a sealing means; E. a sealing means including:: (a) an outer portion adapted to be secured between said valve body and said retaining ring; (b) an offset hinged L-shaped portion integral with said outer portion, said L-shaped portion having a cavity therein adapted to receive a resilient back-up means; (c) a substantially rectangular inner portion integral with said L-shaped portion, said inner portion having a shoulder ring portion on each side thereof, with the shoulder ring portion on one side projecting into the groove of said valve body and the shoulder ring portion on the other side projecting into the groove of said retaining ring; and, (d) a resilient back-up means positioned in the cavity; whereby when said sealing means is pressurized by fluid from either side thereof upon closing of said closure means, the parallel relationship of the planar surface and the axial centerline causes said back-up means and fluid directed on said inner portion to apply their combined forces substantially perpendicular to the peripheral land to effect sealing of said valve.

2. The bi-directional valve of claim 1, wherein the shoulder ring portions cooperatively engage their respective grooves, thereby acting as stop means to control the amount of projection of said sealing means radially into the passage and prevent blow out of said sealing means.

3. The bi-directional valve of claim 2, wherein each of the pair of shoulder ring portions is of substantially trapezoidal configuration.

4. The bi-directional valve of claim 1, wherein said outer portion is secured in a portion of said chamber and is of a volume of mass larger than the volume of material that can be contained in the portion, so that, said outer portion is compressed therein forming a fluid leak-tight seal about its periphery.

5. The bi-directional valve of claim 1, wherein said L-shaped portion is resilient, flexible and substantially of non-conical arcuate configuration, whereby under fluid pressure said L-shaped portion forms a radii-arc shape.

6. The bi-directional valve of claim 2, wherein each of the grooves is of substantially trapezoidal configuration.

7. A bi-directional valve substantially as described herein with reference to the accompanying drawings.