Butterfly valve seal retaining arrangement

A butterfly valve seal arrangement in a butterfly valve having a cylindrical flow channel with a wall includes a seal flange, an elastomeric seal, a seal channel, and an annular seal retaining ring. The seal flange extends into the cylindrical flow channel from the wall of the cylindrical flow channel. The seal channel is recessed into the wall of the cylindrical flow channel adjacent to the seal flange. And the annular seal retaining ring includes tabs extending into the seal channel which hold the annular seal retaining ring in the cylindrical flow channel. An elastomeric seal is held in compression in the seal channel and against the seal flange by the annular seal retaining ring, and extends into the cylindrical flow channel forming a seal surface held in compression against a vane seat of a vane in a position perpendicular to a direction of flow.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention pertains to the field of butterfly valve seals. More particularly, the invention pertains to mechanically retained butterfly valve seals.

Description of Related Art

Butterfly valves generally include a hollow valve body with an inlet and an outlet, and cylindrical flow channel passing between the inlet and the outlet. A vane is rotatably mounted between the inlet and the outlet on an operating stem passing laterally through the hollow valve body. When the operating stem is rotated, the vane may be rotated between a first position perpendicular to a flow direction between the inlet and the outlet, and a second position parallel to the flow direction. An annular elastomeric seal mounted circumferentially in the cylindrical flow channel at the location of the vane mates with a seat ring on the vane when the vane is in the first position, creating a fluid tight seal between the vane and the cylindrical flow channel of the hollow valve body.

In the prior art, various constructions have been used to mount the elastomeric seal in the cylindrical flow channel. In some constructions, the elastomeric seal is bonded to a channel formed in a surface of the cylindrical flow channel using adhesives. Such constructions, however, do not facilitate field replacement of the elastomeric seal, and also may not provide for adjustment of the elastomeric seal. Additionally, experience has shown that bonded elastomeric seal interfaces may fail under high flow velocity conditions.

In other prior art constructions, the elastomeric seal is compressed into a seal channel and against a seal flange by a retaining ring connected to the seal flange using a number of bolts or screws. This arrangement allows for field replacement of the elastomeric seal, and also for adjustment of the elastomeric seal by changing the torque on the screws or bolts holding the retaining ring, and thus the compression of the elastomeric seal between the retaining ring and the seal flange. This type of construction increases machining required during construction of the hollow valve body, and therefore also manufacturing costs.

An elastomeric seal arrangement described by Kennedy (U.S. Pat. No. 4,763,877, issued 1988) also uses an elastomeric seal compressed into a seal channel and against a seal flange by a retaining ring. In this construction, the retaining ring is held in place by at least three J-shaped clips. The elastomeric seal is first placed in the seal channel. The retaining ring is then located next to the elastomeric seal, and pressure is applied to the retaining ring to compress the elastomeric seal, and move the retaining ring past a channel formed in the surface of cylindrical flow channel.

A long end of the J-shaped clips is received by the groove in the surface of the cylindrical flow channel, and a short end of the J-shaped clips is received by a first groove in the retaining ring. When pressure is removed from the retaining ring, the elastomeric seal decompresses and forces the retaining ring against the J-shaped clips. The long end of the J-shaped clips is in turn forced against a side of the groove in the surface of the cylindrical flow channel, holding the J-shaped clips in place. A point-punch may be used to create a deformation of the J-shaped clips into a second groove formed in the retaining ring, so that the J-shaped clips may only be removed using considerable force. The elastomeric seal may be adjusted by inserting a shim between the long end of the J-shaped clips and the side of the channel in the surface of the cylindrical flow channel, thus increasing the compression of the elastomeric seal into the seal channel and against seal flange.

The annular elastomeric seals used in the prior art are generally formed using extrusion or molding techniques to produce an annular seal with a given cross-sectional profile. However, this method of construction limits the types of elastomers that may be used to form the elastomeric seals because not all elastomeric materials lend themselves to these manufacturing techniques. As a result, butterfly valves used to regulate flow in fluid systems carrying aggressive chemicals may require short service intervals between elastomeric seal replacements. For example, in clean water treatment facilities that use concentrated sterilization fluids to clean piping systems, improper flushing of the sterilization fluids after a cleaning cycle may lead to rapid elastomeric seal degeneration, and failure of elastomeric seals.

SUMMARY OF THE INVENTION

A butterfly valve includes a hollow valve body with an inlet, an outlet, and a cylindrical flow channel with a wall passing between the inlet and the outlet. A rotatable operating stem passes laterally through the hollow valve body and cylindrical flow channel at a location between the inlet and the outlet.

A vane with a vane seat formed about a circumference of the vane is located in the cylindrical flow channel and mechanically coupled to the rotatable operating stem such that the vane is rotatable from a first orientation perpendicular to a flow direction between the inlet and the outlet, and a second orientation away from perpendicular to the flow direction.

A valve seal arrangement includes a seal flange, a seal channel in the wall of the cylindrical flow channel, an elastomeric seal, and an annular seal retaining ring.

The seal flange extends radially into the cylindrical flow channel of the hollow valve body from the wall of the cylindrical flow channel adjacent to the vane seat of the vane when the vane is in the first orientation.

The seal channel includes a first side, a second side, and a third side formed in the wall of the cylindrical flow channel. The first side is adjacent to the seal flange, the second side is recessed into the wall of the cylindrical flow channel of the hollow valve body, and the third side is opposite the first side.

The annular seal retaining ring has a series of tabs extending from an outer circumference into the seal channel. An interface between the tabs and the third side of the seal channel holds the annular seal ring in the cylindrical flow channel opposite the seal flange and defines a space between the annular seal ring and the seal flange.

The elastomeric seal is held in the seal channel between the annular seal retaining ring and the seal flange, with the elastomeric seal extending into the cylindrical flow channel through the space defined between the annular seal ring and the seal flange, and forms a seal surface held compression against the vane seat of the vane when the vane is in the first position.

In one embodiment, the elastomeric seal is an O-ring, with a circular cross-section in an uncompressed first state, held in a compressed second state between the annular seal retaining ring and the seal flange. The O-ring elastically deforms to the first side of the seal channel, the second side of the seal channel and the tabs of the annular seal retaining ring, and also elastically deforms through the space defined between the annular seal ring and the seal flange, and into the cylindrical flow channel of the hollow valve body to form the seal surface held compression against the vane seat of the vane when the vane is in the first position.

The O-ring is installed in the seal channel in an uncompressed state. The annular seal retaining ring is then introduced into the cylindrical flow channel of the hollow valve body. Initially the tabs of the annular seal retaining ring are perpendicular to the annular seal ring, so that the annular seal ring may pass through the cylindrical flow channel. An annular press die is used to compress the O-ring been the annular seal retaining ring and the seal flange, and into the seal channel, while moving the annular seal retaining ring toward the seal flange. An annular expansion die surrounding the annular press die then bends the tabs of the annular seal retaining ring into the seal channel.

When the annular expansion die and the annular press die are removed from the cylindrical flow channel, the elastomeric seal expands and an interface between the tabs of the annular seal retaining ring and the third side of the seal channel holds the annular retaining ring in place.

DETAILED DESCRIPTION OF THE INVENTION

A butterfly valve seal arrangement of the type described herein provides several advantages over the prior art. An elastomeric seal is preferably formed from commercially available bulk O-ring cord, which results in a broader range of elastomeric materials being available to choose from in constructing the elastomeric seal, allowing the construction of elastomeric seals that are more compatible with a range of aggressive fluids. Additionally, the elastomeric seal provides greater resistance to butterfly disk movement and high flow velocity drag that may otherwise cause an elastomeric seal to be pulled from its working location over time.

FIG. 1shows a hollow valve body10of a butterfly valve. The hollow valve body10has a first end with an inlet35, and an inlet flange15surrounding the inlet35for attachment to a piping system. A second end of the hollow valve body10has an outlet, and an outlet flange20for attachment to a piping system. A cylindrical flow channel30between the inlet35and the outlet is defined by a generally cylindrical wall internal to the hollow valve body10. The hollow valve body10is provided with a first stem aperture25aand a second stem aperture25bat opposing sides of the hollow valve body10. The first stem aperture25aand a second stem aperture25bare in alignment such that an operating stem may pass through first stem aperture25a, an aperture in a butterfly disk, and the second stem aperture25b. A seal flange45and seal channel50are also shown.

FIG. 2shows a cross-section through the hollow valve body10from the inlet35to the outlet40. The seal flange45extends radially into the cylindrical flow channel30from a wall31of the cylindrical flow channel30, and adjacent the first stem aperture25a(not shown in this view) and second stem aperture25b. A seal channel50is formed in the wall31of the cylindrical flow channel30adjacent the seal flange45. The cylindrical flow channel30between the seal channel50and the inlet35has a diameter dc.

The seal channel50has a profile in the wall31of the cylindrical flow channel30, indicated by3inFIG. 2, and shown in greater detail inFIG. 3. The profile of the seal channel50includes a first angled50asegment, a straight segment50b, an arcuate segment50c, and a second angled segment50d, together forming a generally dove-tail shape for the seal channel50. In this embodiment, the first side of the seal channel is formed by the second angled segment50dand the arcuate segment50c, the second side of the seal channel is formed by the straight segment50b, and the third side of the seal channel is formed by the first angled segment50a.

The seal flange45has a first side that is coincident with the second angled segment50dof the seal channel50, and a second side opposite the first side toward the outlet40of the hollow valve body10.

FIG. 4Ashows a perspective of an annular seal retaining ring60with an outer diameter dr. A series of tabs60aare formed about the outer circumference of the annular seal retaining ring60, with adjacent tabs60abeing separated by gaps60b. A cross-sectional profile of the annular seal retaining ring60along a radius of the annular seal retaining ring is shown inFIG. 4B, and illustrates that the tabs60aare generally perpendicular to the annular seal retaining ring60. The annular seal retaining ring60is, in one embodiment, made of stainless steel, and stamped from sheet stock. However, any other material, such as aluminum or brass, for example, that is compatible with fluids passing through the butterfly valve, and that may be formed into the shape of the annular seal retaining ring60, may also be used.

In one embodiment, an elastomeric seal is formed from an O-ring, which can be made from commercially available bulk O-ring cord, or could be purchased as a commercially available finished O-ring. The O-ring may be constructed from any elastomeric material known in the art, including, but not limited to, silicon rubber, nitrile rubber, ethylene propylene diene monomer (EPDM) rubber, or Viton® fluoroelastomer. An elastomeric seal of any desired diameter may be constructed by cutting a segment of O-ring cord to an appropriate length and joining the two ends of the segment of O-ring cord using any method known in the art and appropriate to the elastomeric material chosen. In a non-compressed state, the O-ring cord, and the elastomeric seal constructed from the O-ring cord, has a circular cross-sectional profile in one embodiment. In other embodiments, the O-ring may have a pre-formed cross-sectional profile.

The elastomeric seal is installed in the hollow valve body10as shown inFIGS. 5A-5F. As shown inFIG. 5A, the elastomeric seal65is first inserted into the cylindrical flow channel30in an uncompressed state, and fitted into the seal channel50and against the seal flange45. The diameter drof the annular seal retaining ring60is slightly less than the diameter dcof the cylindrical flow channel30, allowing the annular seal retaining ring60to be slid into the inlet35, and through the cylindrical flow channel30. As shown inFIG. 5B, the annular seal retaining ring60is thus located so that the annular seal retaining ring60abuts the uncompressed elastomeric seal65. An annular press die D1with a radial cross-sectional profile similar to the profile shown inFIG. 5Bis inserted into the cylindrical flow channel30, and pressed against the annular seal retaining ring60, such that the a uniform pressure is applied to the annular seal retaining ring60about a circumference of the annular seal retaining ring60, and toward the seal flange45.

As shown inFIG. 5C, when pressure is applied to the annular press die D1, for example, using a hydraulic press, the elastomeric seal65elastically deforms into the seal channel50, against the seal flange45, and against the annular seal retaining ring60. For the purposes of the description contained herein, “elastic deformation” is defined as the property of a material which, when the material is in a first resting state with a first shape, allows the material to deform to a second state with a second shape when an external force is applied to the material, and return to the first resting state with a first shape when the external force is no longer applied to the material. In other words, a material having been elastically deformed, and held in the second state with the second shape, will be biased to return to the first state with the first shape, until an external force causing the deformation is removed, and the material fully relaxes to the first state with the first shape.

The annular seal retaining ring60is pressed against the elastomeric seal65until the tabs60aof the annular seal retaining ring60are adjacent first angled segment50aof the seal channel50. When the annular seal retaining ring60is at the position shown inFIG. 5C, an annular expansion die D2that is concentric to, and surrounding the annular compression die D1, with radial cross-sectional profile similar to that shown inFIG. 5C, is moved into the cylindrical flow channel30toward the seal flange45.

As shown inFIG. 5D, as the annular die D2moves toward the seal flange45, the annular die D2contacts the tabs60aof the annular seal retaining ring60, and bends the tabs60ainto the seal channel50. As shown inFIG. 5E, when the annular press die D1and annular expansion die D2are removed from the cylindrical flow channel30, the elastomeric seal65, being biased to return to a first state with a circular cross-sectional profile, expands and forces the annular seal retaining ring60toward the inlet35until the tabs60acontact the first angled segment50aof the seal channel50.

Further motion of the annular seal retaining ring toward the inlet35is thus prevented, and the elastomeric seal65is held in the dove-tail, being wider at straight segment50bthan at the wall31of the cylindrical flow channel30, of the seal channel50formed by the straight segment50b, the arcuate segment50c, and the second angled segment50dof the seal channel50, as well as the annular seal retaining ring60, and the tabs60abeing bent into the seal channel50. A portion of the elastomeric seal65elastically deforms into the cylindrical flow channel30and defines a seal surface66.

As shown inFIG. 5F, the seal surface66may be adjusted, if desired, by placing a shim51at an interface between the tabs60aof the annular seal retaining ring60, and the first angled segment50aof the seal channel50.

The elastomeric seal65is held in a state of elastic deformation in the seal channel50by the annular seal retaining ring60. The elastomeric seal65is therefore biased to return to the circular cross-sectional profile of the elastomeric seal65prior to being compressed by the annular seal retaining ring60. As a result, the elastomeric seal65is biased to fill the seal channel50and be forced against the annular seal retaining ring60and tabs60a.

When a force is applied to the seal surface66of elastomeric seal65that may tend to roll the elastomeric seal65out of the seal channel50, the force is opposed by the elastic deformation properties of the elastomeric seal65, which bias the elastomeric seal65to return to a circular profile more closely approximated by the seal channel50, rather than a profile that may allow the elastomeric seal65to move between the seal flange45and the annular seal retaining ring60, and become dislodged.

Similarly, in the event the elastomeric seal65is drawn a small distance out of the space between the seal flange45and the annular seal retaining ring60, the elastic deformation properties of the elastomeric seal65cause the elastomeric seal65to be self-seating and return to the seal channel50, as the elastomeric seal65is biased to return to a circular profile which is more closely approximated by the dove-tail space formed by the straight segment50b, the arcuate segment50c, and the second angled segment50dof the seal channel50, as well as the annular seal retaining ring60, and the tabs60abeing bent into the seal channel50.

FIG. 6shows an exploded view of a butterfly valve incorporating a butterfly valve seal arrangement described herein. The butterfly valve includes a hollow valve body10with an inlet35, an inlet flange15, an outlet flange20, first stem aperture25a, and other elements previously described inFIGS. 1-2. The elastomeric seal165and annular seal retaining ring60are inserted into the inlet35and fixed in the hollow valve body as previously described inFIGS. 5A-5F. In this figure the elastomeric seal165in an O-ring that has a pre-formed cross-sectional profile, and may be installed in the seal channel50in the same manner as previously described herein for an elastomeric seal65that is an O-ring with a circular cross-sectional profile.

A vane80includes a vane aperture80afor receiving an operating stem70. The vane80has a vane face80bwith a recess80cmachined about a circumference of the vane face80bfor receiving a vane seat81. The vane seat81is received by the recess80cmachined in the vane face80b, and is held in place with screws82, bolts, rivets, welds, or other types of fastener. The vane seat81is made of stainless steel in one embodiment, but may also be formed from other materials that are compatible with fluids flowing through the butterfly valve, and other butterfly valve materials, including but not limited to bronze, aluminum, nickel allow, composite materials, and plastics.

The assembled vane seat81and vane80are inserted into the hollow valve body10through the outlet40, not shown in this view, and moved to a location in the hollow valve body10with the vane seat81contacting the seal surface66of the installed elastomeric seal65. An operating stem70is then inserted through the second stem aperture25b, through the vane aperture80a, and into the first stem aperture25a. A vane retaining pin83passes through the vane80and the operating stem70so that the vane80and the operating stem70are mechanically coupled, both rotationally, and longitudinally along a length of the operating stem70. A bushing75is inserted into the first stem aperture25afrom the exterior of the hollow valve body10, and is held in contact with an end of the operating stem70inside the first stem aperture25aby a first stem cap71. The first stem cap71is held in place by fasteners, such as screws79or bolts, for example. A second stem cap, not shown in this figure, seals the second stem aperture25b, with the operating stem70passing through the second stem cap.

FIG. 7illustrates a longitudinal cross-section of an assembled butterfly valve having a valve seal arrangement as described herein. The vane80is shown in a first orientation, closing the butterfly valve and blocking flow of a fluid from the inlet35to the outlet40through the cylindrical flow channel30. In this first orientation, the vane seat81is in contact with the elastomeric seal65about a circumference of the vane seat. The vane80may be moved to a second orientation allowing a fluid to flow through the cylindrical flow channel by rotating the operating stem70, and consequently the vane80mechanically coupled to the operating stem, as indicated by the dashed arrows inFIG. 7. As the operating stem70is rotated, a first half of the vane80rotates toward the outlet40and away from the elastomeric seal65. At the same time, a second half of the vane80rotates past the elastomeric seal65and away from the elastomeric seal65toward the inlet35. The operating stem70may be rotated by any means known in the art, including, but not limited to, worm gear drives and actuator levers.

FIG. 8illustrates the seal arrangement and vane80in more detail, as indicated by the reference8inFIG. 7. The elastomeric seal65is shown installed in the seal channel50as previously described inFIGS. 5A-5F. The vane seat81is mounted in a recess80cin the vane80. An O-ring90or other seal may be incorporated between the vane seat81and the vane80to prevent fluid from leaking between the vane seat81and the vane80. A seat surface85is formed at an outer circumference of the vane seat81. When the vane80is in the first orientation, closing the butterfly valve, the seat surface85contacts the elastomeric seal65at the seal surface66. Elastomeric compression of the elastomeric seal65at the seal surface66by the seat surface85forms a fluid tight seal at the interface between the seal surface66and the seat surface86.