FR2529634A1 - Sealing device for a bi-directional valve, and valve using such a device. - Google Patents

Abstract

The invention relates to a bi-directional valve. It is related to a butterfly valve in which a sealing device 60 is formed between the body 14 of the valve and a retaining ring 40. The sealing device comprises a sealing surface 36 which is applied against the shut-off by an endless spring 50, whilst annular shoulders 35 and 37 limit the movement of the seal and allow the application of the forces of the spring 50 and those due to the pressure of a fluid in a direction which is substantially perpendicular to the surface 36. Application to the manufacture of butterfly valves for withstanding high pressures.

Description

 The present invention relates to bidirectional valves and in particular an original construction of a sealing device having applications in butterfly valves. Butterfly valves have many advantages over other types of valves for regulating fluid flow rates, the most important advantage being the reduction in cost to the manufacturer, ease of opening and low shrinkage. the fluid flow section in the fully open position. However, the use of these valves is generally limited to low pressure applications since they cannot provide a significant seal at high pressures. In some known valves, the seals are placed in grooves formed in the body of the valve. the valve and they are often flushed out when the valve is open, so that fluid can flow around the seal. In other known valves, a high pressure fluid can leak through the valve flowing between the body and the seal while in many other known valves, contact between the disc and the seal must be very tight to prevent leaks, to the point that opening the valve, especially when it has a large diameter, requires significant torque. In addition, in several known valves, used in applications at high pressure and / or at high temperature, the sealing device or the ring forming a seat loses its properties of application of a desired preliminary load on the sealing face of the ring forming the seat when the ring expands. In other floating seal valves, a high pressure fluid which enters the cavity when the valve is closed cannot escape when the valve is open, so that the seal is forced out.

 In other floating seat valves, attempts have been made to reduce the torque necessary for opening and closing the shutter disc while improving the retention of the sealing face of the seat ring when this ring expands, by using the indirect or partial application of the forces exerted by a pressurized fluid and by an elastic device to the sealing face.

 The invention relates to a highly improved bidirectional valve which does not leak and in which the seal is not driven out when high pressure fluids are present, the valve being able to be controlled with a relatively low torque.

 The invention also relates to a reliable valve seat, of exceptionally long duration, relatively inexpensive and of easy replacement and maintenance.

 It also relates to a bidirectional valve having an improved sealing device which fully implements the advantages of the direct application of forces due to the pressure of the fluid and to an elastic device on the sealing face.

 The bidirectional valve according to the invention comprises a body having a fluid circulation passage and a cavity near the passage, having a flat surface. A retaining ring removably attached to the body also has a cavity. The cavities form a chamber which opens into the passage and which has a central axis parallel to the flat surface of the valve body. The retaining ring is intended to hold a sealing device in the body. A shutter, placed in the passage so that it can pivot, and having a peripheral bearing, is intended to cooperate with a sealing device.

 The sealing device has an original structure comprising a seat ring and an elastic support device. The seat ring has an external part, a substantially rectangular internal part having a sealing surface and a shoulder ring arranged on both sides, and an L-shaped and offset part, connecting the internal and external parts which are thus integral. . The sealing surface has a circumferential release groove. The L-shaped part has an internal cavity intended to accommodate an elastic support device, so that, in the presence of a pressurized fluid acting on the device. sealing on one side or the other, a fluid-tight and dynamically repelled seal is established between the sealing device and the peripheral surface of the shutter so that the forces exerted by the fluid under pressure and by the device elastic support on the peripheral bearing are substantially perpendicular to this bearing.

Other characteristics and advantages of the invention will emerge more clearly from the description which follows, given with reference to the appended drawings in which
Figure 1 is a plan section of a butterfly valve comprising the sealing device or seal according to the invention, the shutter being shown in solid lines in its closed position and in phantom in its open position
Figure 2 is an enlarged section of the seal of Figure 1, when not subjected to forces, this condition occurs when the valve is open and allows the circulation of the fluid
Figure 3 is an enlarged section of the seal of Figure 1 when it is in its preload condition, which takes place when the shutter is closed and when the pipe is not under pressure
Figure 4 is an enlarged section of the seal of Figure 1 when subjected to a preload and pressure, this condition being observed when the shutter is closed and when there is a pressure difference between and 'Other of the shutter, that is to say that pressurized fluid is placed in the channel which is formed on one side of the sealing device; and
Figure 5 is an enlarged section of the seal of Figure 1, the seal being subjected to a prior charge and to the pressure of the fluid, this condition being observed when the shutter is closed and when there is a difference in pressure from and on the other side of the valve, the pressurized fluid exerting a force on the side of the sealing device opposite to that shown in FIG. 4.

Reference is made to the drawings and more specifically to FIG. 1 which represents a valve bearing the general reference
10 having a passage 12 for circulation of a fluid formed in a body 14, the valve being placed in a conduit 18. The valve 10 can be fixed in the conduit by welding, using bolted flanges or in any other way known. A shutter such as a shutter disc 21 having a curvilinear peripheral surface 22, is shown in solid lines in the closed position and in phantom in the open position.

The disc 22 is fixed to the rod 16 which protrudes therefrom and it is supported by the body 14 so that the rod can have an axial displacement The rod 16 has a handle or another device (not shown) which is fixed to it conventionally so that it forms an axis around which the disc 21 can be rotated so that the circulation passage 12 is open or closed. A sealing device 30 comprises a ring 31 forming a seat and an elastic support device such as a spring 50, and it is disposed between the body 14 and the retaining ring 40 which is removably connected to the body 14 by retaining devices 42, as shown. As the axis of rotation of the disc 21 does not coincide with a central axis passing through the ring 31, the disc has an eccentric movement relative to the ring 31, so that the separation of the disc 21 and the ring 31 is faster than in the case where the central axes of the disc and
the ring coincided. However, the invention can also be implemented coincidentally with the axis of rotation of the disc and the central axis of the ring forming the seat.

As shown in Figure 2, the body 14 of the valve has a cavity formed by planar surfaces 72 and 72A which are separated by a first intermediate groove 76 and by a second groove 78 which is adjacent to the surface 72. The ring Retaining 40 has a cavity delimited by surfaces 82 and
82A juxtaposed with the surfaces 72 and 72A respectively and separated by an intermediate groove 86, the first surface 88 extending the surface 82, but in a plane perpendicular to the latter, while the surface 89 extends the surface 88, in a plane which is practically perpendicular to it.

 The aforementioned cavities of the body 14 and of the ring 40 delimit a chamber 60 intended to house the sealing device 30. It should be noted that the chamber 60 is arranged so that its central axis is parallel to the flat surface 72 of the body 14 of the valve.

 The sealing device 30 comprises a ring 31 forming a seat, formed of a material which resists heat and chemicals, for example a fluorocarbon, urethane, or elastomer polymer, and an elastic support device, by example an endless metal spring 50. The ring 31 forming a seat has an external part 32, an L-shaped part 33 and an internal part 34 which are formed in one piece. When the disc is in the open position and when the retaining ring 40 is fixed to the body 14, the external part 32 is preferably tightened so that it is retained in place in the region delimited by the second groove 78 and the surface 89. The volume or the mass of the external part 32 is greater than the volume or the mass of the material which can be contained between the second groove 78 and the surface 89 placed opposite, so that the external part is compressed inside and forms a tight seal at the periphery. This region preferably has a smaller dimension along the axis AA ′ formed by connection of the contact points of the surface 88 and of the surface 89 on the one hand and of the surface 72 and of the second groove 78 of on the other hand, so that the external part is permanently retained. Although such an embodiment is advantageous, the external part 32 can have any suitable configuration allowing it to be retained by a suitable device.

 The part 33 which is connected to the external part 32 of which it is integral, has a cavity 55 intended to accommodate the spring 50 which exerts opposing or supporting forces on the structure which is in contact with it and prevents the part from sagging 33 when pressure differences are exerted on the side of the ring 31 which faces the retaining ring. The cavity 55 has a flat base surface 59.

The part 33 is freely suspended from the part 32 in the chamber 60, so that the pressures exerted on either side of the ring 31 cause the parts 33 and 34 to move around the axis AA ′, like a hinge . The part 33 has a surface 91 which is preferably chamfered or cut so that a larger part of the chamber 60 is unoccupied and allows free movement of the parts 33 and 34 around the axis AA ', without obstacle. The part 33, although it is elastic and flexible, has a non-conical L-shaped configuration which, when it is subjected to a force due to the fluid under pressure, takes on an arc shape.

 The internal part 34 which is integral with the part 33, has a substantially rectangular shape in section, and it has a sealing surface 36. The internal part 34 has annular parts 35 and 37 forming shoulders which protrude into the grooves 86 , 76 and allow the limitation of the projection of the ring 31 forming a seat in the passage 12 and preventing the ejection of this ring 31 when the disc is open or closed. The sealing surface 36 has an axial extent AD and a circumferential groove 70 is placed in its axial central part. The groove 70 is limited axially by circumferential edges B and C, the axial distance separating the edges D and C preferably being greater than the axial distances AB and CD arranged on either side of the groove. Preferably, the axial dimensions AB and CD are equal. The groove 70 has an axial dimension of approximately 0.25 mm which must be equal to the displacement distance when the disc comes into contact with the sealing ring 31. The surface 36 sealing is preferably substantially parallel to the base surface 56 and it may have a general spherical, conical or other configuration. The parts 35 and 37 preferably have a trapezoidal configuration in section. As the chamber 60 has a width greater than that of the parts 33 and 34, channels 100, 101 are formed between the parts 33 and 34 and the cavities of the ring 40 and of the body 14 respectively, so that the introduction of the ring 31 forming a seat in the chamber 60 is facilitated, the pressurization or depressurization of the cavity 55 is facilitated, and the different parts can move freely during the operation of the valve. The channel 101 has an axial dimension greater than both to the axial dimension of the channel 100 and to the axial displacement allowed to the control rod.

 As shown in FIG. 3, in the closed position, but without applying pressure, the disc 21 causes the bearing 22 to jam on the internal part 34, so that the sealing surface 36 undergoes expansion towards the outside and forms two linear joints at the circumferential edges B and C in the zone 110.

 In FIG. 4, pressurized fluid is introduced into the channel 100. The component 120 of the forces applied by the pressurized fluid normally acts on the parts 33 and 34 so that they pivot around the axis AA '.

The spring 50 which prevents sagging of the part 33, displaces the latter until it is completely compressed against the flat surface 72. The displacement of the parts 33 and 34 causes an axial widening of the channel 100 and the contact of the internal part 34 and the annular shoulder part 37 with the surface 72A and the groove 76 respectively so that a greater displacement of the internal part 34 is no longer possible.

 The component 122 of forces exerted by the fluid acts radially on the part 33 and pushes the latter and the spring 50 downwards, the force being transmitted by the internal part 34 directly to the sealing surface 36. Since the flat surface 72 is parallel to the central axis LL of the chamber 60 and that the sealing surface 36 is parallel to the base surface 59, all the component 122 of the force exerted by the fluid and the component 51 of the force exerted by the spring when it has not bent, are exerted directly on the sealing surface 36, and thus cause the application of a dynamic load to the edges B and C.

Consequently, the direct application of these forces causes an application substantially perpendicular to the bearing 22 at the edges B and C, so that the seal at the two linear joints formed by the bearing and the edges B and C is excellent.

 In FIG. 5, fluid under pressure is transmitted in the channel 101. The component 130 of the force due to the fluid acts normally on the internal part 34 and in the cavity 55 of the part 33 by causing the pivoting of the parts 33 and 34 around the axis AA ′, and the axial widening of the channel 101, as well as the contact of the surface 91 with the cavity of the ring 40. The internal part 34 and the annular shoulder part 35 are in abutment against the surface 82A and groove 86 respectively.

 The force 130 exerted by the pressurized fluid can be divided into components 56, 57 and 58. The surfaces 82, 88 retain the part 33 when it is subjected to the forces corresponding to the components 56 and 58 respectively.

The component 57, as well as the force 51 applied by the spring in the non-flexed state, are transmitted by the internal part 34 directly to the sealing surface 36, so that the edges B and C undergo an increased dynamic load by direct application, these forces being applied in a direction substantially perpendicular to the surface 22 at the edges B and C, so that the seal at the level of the linear joints formed by the surface and the edges B and C is excellent.

 When the sealing surface 36 wears out during use, the tops of the edges B and C gradually wear out and each linear joint formed by each edge with the bearing surface 22 forms a strip which widens axially. Finally, the two sealing strips are connected and form only one. More precisely, the top of edge B widens outwards towards A and F, the central point of the groove 70 while the top of edge C widens outwards towards D and F. Consequently , the axial distance AB is preferably initially equal to the axial distance CD so that the axial extent of the two sealing strips is practically the same throughout the period of use of the ring 31.

 It is understood that the invention has only been described and shown as a preferred example and that any technical equivalence can be made in its constituent elements without going beyond its ambit.

Claims (9)

1. Bidirectional valve, characterized in that it comprises  A. a valve body (14) having a circulation passage and a cavity near the passage, the cavity having a flat surface with a groove (-76),  B. a retaining ring (40) surrounding the passage and removably attached to the body, the ring having a cavity which has a surface having a groove (86),  C. a chamber (60) connected to the passage and formed between the cavities, the chamber having a central axis parallel to the planar surface,  D. a shutter (21) arranged in the passage so that it can pivot between an open position and a closed position in which it allows and prevents the circulation of the fluid respectively, the shutter having a peripheral bearing intended to be in contact with a sealing device, and  E. a sealing device (30) which comprises  - an external part (32) intended to be fixed  between the valve body and the retaining ring,  - a part articulated in L (33) which is deca  linked but integral with the external part, this part  in L having a cavity intended to accommodate a device  elastic support, the cavity having a base surface  - a substantially rectangular internal part  re (34) integral with the L-shaped part, the internal part  having a sealing surface which is substantially  parallel to the base surface, the inner part  having an annular shoulder portion (35, 37) on  each face, the annular shoulder portion of a  face protruding into the throat of the body and the part  shoulder annular on the other side protruding into  the groove of the retaining ring, and  - an elastic support device (50) placed  in the cavity and exerting support forces  on the L-shaped part so that it cannot  to crash,  - so that when the sealing device is subjected to the pressure of a fluid, applied on one side or the other when the shutter is closed, the parallelism of the flat surface with the central axis and of the sealing surface with the base surface causes the application of the combined forces of the bearing device and of the fluid on the internal part practically in a direction perpendicular to the peripheral bearing, so that the sealing of the valve is excellent . 2. Valve according to claim 1, characterized in that each of the two annular shoulder portions (35, 37) has a substantially trapezoidal configuration. 3. Valve according to claim 1, characterized in that the external part (32) is fixed in a part of the chamber and has a volume greater than that which can be contained in this part, so that the external part is compressed and forms a fluid tight seal at its periphery.  4. Valve according to claim 1, characterized in that the L-shaped part (33) is elastic, flexible and of substantially non-conical curved configuration, so that, when a fluid exerts a pressure, the L-shaped part takes a form in an arc. 5. Valve according to claim 1 characterized in that each of the grooves (76, 86) has a substantially trapezoidal configuration. 6. Valve according to claim 1, characterized in that the sealing surface (36) has a circumferential groove (70) for release. 7. Valve according to claim 6, characterized in that the release groove (70) is in the axially central position of the sealing surface, and the sealing surface parts which are placed on either side of the groove has an identical axial dimension. 8. Valve according to claim 6, characterized in that the release groove (70) has an axial dimension greater than that of the sealing surface parts which are on either side of the groove. 9. Bidirectional valve, characterized in that it comprises  A. a valve body (14) having a circulation passage which passes through it and a cavity close to the passage, the cavity having a flat surface which has a groove (76),  B. a retaining ring (40) surrounding the passage and removably fixed to the body, the ring having a cavity one surface of which has a groove (86),  C. a chamber (60) which communicates with the passage and which is formed between the cavities, the chamber having a central axis parallel to the planar surface,  D. a disc (21) fixed to a rod and arranged in the passage so that it can pivot around the rod between an open position and a closed position, allowing or preventing respectively the circulation of the fluid in the valve, the disc having a peripheral surface intended to cooperate with a release groove,  E. a rod (16) supported by the body and allowing axial movement, and  F. a sealing device (30) which comprises  - an external part (32) intended to be fixed between the body and the retaining ring,  - an L-shaped articulated part (33) which is offset and secured to the external part, the L-shaped part having a cavity intended to accommodate an elastic support device, the cavity having a base surface,  - a substantially rectangular internal part (34) integral with the L-shaped part and having a sealing surface which has a circumferential release groove, the sealing surface being substantially parallel to the base part and the release groove being limited by two circumferential grooves, the internal part having a first annular shoulder part (35) on one side, projecting into the groove of the valve body, and a second annular shoulder part (37) on the other side , protruding into the groove of the retaining ring, a channel being formed between each part  shoulder annular and the corresponding groove, so that the axial extent of the channel formed between the first part  shoulder annular and its groove is greater than the distan  this axial between the second annular shoulder part  and the corresponding groove, the first distance being  greater than the possible axial displacement of the rod, and  - an elastic support device (50) placed  in the cavity and exerting support forces on the part  in L so that it cannot crash,  - So much so that when the shutter is closed  the peripheral span forms a linear joint with each of the  two circumferential edges, and that,  - when the sealing device is  subject to fluid pressure on either side after  shutter closing, parallelism of the flat surface  with the central axis on the one hand and the sealing surface  with the base surface on the other hand causes the application of  combined forces of the support device and the working fluid  on the internal part in a substantially perpendicular direction  to the peripheral range, so that the tightness of the valve  at the two linear joints is excellent.