Diaphragm and backing cushion shaping for increased membrane life

A weir-type diaphragm valve includes a valve body with a fluid channel and a weir with a weir sealing portion; and a diaphragm with diaphragm portions, including a diaphragm weir sealing portion at the weir that responds to one force and travel against the weir sealing portion to close the valve and stop fluid flow through the fluid channel, and responds to a second force and travel away from the weir sealing portion to open the valve and allow fluid through the fluid channel, a center flexing portion off the weir that experiences convex and concave flexing extremes when the valve is closed/opened, and an outer sealing portion fully constrained between components, one of which includes the valve body, when the valve is closed/opened. The diaphragm portions have different characteristics based on different material stresses associated with different functionality that each portion performs when the valve is closed/opened.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a diaphragm valve; and more particularly relates to a diaphragm valve having a weir.

2. Brief Description of Related Art

FIGS. 1ato1dshow different parts of a known weir-type diaphragm valve. InFIG. 1a, a diaphragm valve is sealed by a membrane, the diaphragm (1), which must repeatedly travel from a sealed position, against the body weir (2) to an open position. The diaphragm (1) is typically opened with a metal stud (3) embedded within the membrane. An outer seal of the diaphragm (1) is fully constrained while the center of the diaphragm (1) typically experiences the majority of travel to facilitate the open and closed positions. The shape cycles between convex and concave extremes for closed and open positions respectively. As a result, locations of greatest deformation, from bending magnitude and geometry such as thickness, result in the highest material stress. Although the membrane material is chosen to be compliant to these mechanical cycles, it has limitations, especially when combined with certain process requirements, such as extreme cold, heat and/or steam conditions. These conditions weaken the material such that areas of high mechanical stress can limit the life expectancy of the diaphragm. InFIG. 1a, the weir-type diaphragm valve has a backing cushion (4) that acts as a compliant spring membrane between a metal compressor (5) and the plastic diaphragm (1), typically made from Teflon.

SUMMARY OF THE INVENTION

In summary, the present invention consists of four design feature solutions to reduce the stress associated with the functioning of a diaphragm in a weir-type diaphragm valve. They can be used individually, or in tandem, and are summarized as follows:

1) Deviation from rotational symmetry:a) Match the weir shape when in the closed position only on the weir, andb) Shape membrane on either side of weir to reduce resistance to diaphragm inversion.

2) Form a diaphragm “free” shape between open and closed requirements:a) Balances the tensile and compressive material stress extremes during mechanical cycling, andb) Facilitates easier diaphragm installation with a midway compressor position.

3) Vary the diaphragm thickness:a) Thin locations which require the greatest bending during mechanical cycling,b) Thicken areas which experience minimum bending, andc) Thin Elastomer material that is not located at sealing areas such as the weir.

4) Reduce weir bead height or eliminate weir bead in areas of greatest membrane inflection in order to eliminate tensile crack propagation in the sealing bead.a) Small cross section of bead cannot resist bending,b) Bead outer fiber forced into high compressive and tensile deformation, andc) Cracks develop perpendicular to the bead length, thereby defeating the seal.

Moreover, the diaphragm shaping methods according to the present invention can reduce the force required to open the diaphragm. The diaphragm is typically opened with a stud embedded within the membrane. Reduction of this opening force reduces the stress in the elastomer or plastic material encapsulating the stud, resulting in increased life expectancy for the diaphragm.

Moreover still, in many cases the aforementioned features may also be applied to the backing cushion as well, which acts as a compliant spring membrane between the metal compressor and the diaphragm. Selective thickening, thinning, and shaping of this component has similar benefits.

Specific Embodiments

According to some embodiments, the present invention may take the form of apparatus, including a weir-type diaphragm valve that features a valve body and a diaphragm. The valve body may be configured with a fluid channel and a weir having a weir sealing portion. The diaphragm may be configured with two or more diaphragm portions, includinga diaphragm weir sealing portion at the weir to respond to one force and travel against the weir sealing portion to close the weir-type diaphragm valve and stop fluid flow through the fluid channel, and respond to a second force and travel away from the weir sealing portion to open the weir-type diaphragm valve and allow fluid flow through the fluid channel,a center flexing portion off the weir configured to experience convex and concave flexing extremes when the weir-type diaphragm valve is closed and opened, andan outer sealing portion configured to be fully constrained between components, one of which includes the valve body, when the weir-type diaphragm valve is closed and opened.
The two or more diaphragm portions are configured with different characteristics based at least partly on different material stresses associated with different functionality that each portion is configured to perform when the weir-type diaphragm valve is closed and opened.

The present invention may also include one or more of the following features:

Deviation from Rotational Symmetry

According to some embodiments of the present invention, the different characteristics may be based at least partly on the shape of the diaphragm weir sealing portion at the weir, including being based at least partly on a deviation from a rotational symmetry. By way of example, the shape of the diaphragm weir sealing portion at the weir matches the shape of the weir sealing portion. Moreover, the center flexing portion off the weir may also be shaped to reduce stress with inflection, e.g., including shaping the center flexing portion on either side of the weir to reduce resistance to diaphragm inversion. Moreover still, the diaphragm weir sealing portion may include a pair of studs embedded therein and configured perpendicular to the weir to initiate inflection with lower stress.

Form a Diaphragm “Free” Shape Between Open and Closed Requirements

According to some embodiments of the present invention, the different characteristics may be based at least partly on forming a diaphragm “free” shape between open and closed requirements of the weir-type diaphragm. By way of example, the diaphragm “free” shape may include, or take the form of, configuring the diaphragm by balancing tensile and compressive material stress extremes during mechanical cycling with the added benefit of facilitating easier diaphragm installation with a midway compressor position.

Vary the Diaphragm Thickness

According to some embodiments of the present invention, the different characteristics may be based at least partly on the thickness of the two or more diaphragm portions. For example, the diaphragm weir sealing portion at the weir may be configured with thickened padding to achieve the required function of geometrical compliance between the compressor and body; the center flexing portion off the weir may be configured with thin locations or elastomeric material which require the most bending or flexing during mechanical cycling; and/or the thin locations or elastomeric material may be configured at least partially around the center flexing portion. Moreover, the center flexing portion off the weir may be configured with thickened locations in areas of low flexure for increased membrane pressure strength; and/or the thickened locations may be configured at least partially around the center flexing portion. Moreover still, the center flexing portion off the weir is configured with: thin locations or elastomeric material which require the most bending or flexing during mechanical cycling, the thin locations or elastomeric material being configured at least partially around the center flexing portion; thickened locations in areas of low flexure for increased membrane pressure strength, the thickened locations are configured at least partially around the center flexing portion; and/or the thin locations or elastomeric material and the thickened locations may be configured so as to alternate. Furthermore, the outer sealing portion may be configured, thickened or thinned, to generate required sealing pressure across the weir, between metal components, when the weir-type diaphragm valve is closed.

Reduce Weir Bead Height or Elimination of Weir Bead in Areas of Greatest Membrane Inflection

According to some embodiments of the present invention, the diaphragm may be configured without, or with a substantially reduced, weir bead height, particularly in areas of greatest membrane inflection.

Different Material Stresses

According to some embodiments of the present invention, the different characteristics may be based at least partly on different material stresses associate with deformations of the two or more diaphragm portions. For example, the diaphragm weir sealing portion may have a first physical characteristic based at least partly on one type of diaphragm surface stress at the weir related to the pushing and pulling of the weir sealing portion to and from the weir in order to close and open the weir-type diaphragm valve, and the center portion may have a second physical characteristic based at least partly on another type of diaphragm surface stress off the weir related to mechanical cycling of the center flexing portion when opening and closing the weir-type diaphragm valve.

The Backing Cushion

According to some embodiments of the present invention, the weir-type diaphragm valve may include a backing cushion as a compliant spring membrane between a metal compressor and the diaphragm, and the backing cushion may include two or more backing cushion portions configured with different characteristics based at least partly on different material stresses associated with different functionality that each portion is configured to perform when the weir-type diaphragm valve is closed and opened

Summary and Advantages

In summary, the present invention increases the life expectancy of the diaphragm by reducing the surface stress incurred during mechanical cycling, particularly during exposure to destructive process such as steam and cold. With some of the described features, a related reduction in the force required to open the diaphragm additionally benefits life of the diaphragm membrane surrounding the opening mechanism, typically an embedded metal stud.

DETAILED DESCRIPTION OF THE INVENTION

According to some embodiments, the present invention may take the form of apparatus, including a weir-type diaphragm valve generally indicated as10,10′ (e.g., seeFIGS. 2a,3a), that features a valve body12and a diaphragm14,14′. The valve body12may be configured with a fluid channel12aand a weir12bhaving a weir sealing portion12c. The diaphragm14,14′ may be configured with two or more diaphragm portions or areas14a,14b,14c(FIGS. 2a,2b);14a′,14b′,14c′ (FIGS. 3a,3b);14a″,14b″,14c″ (FIG. 4), includinga diaphragm weir sealing portion14a,14a′,14a″ at the weir12bto respond to one force and travel against the weir sealing portion12cto close the weir-type diaphragm valve10and stop fluid flow through the fluid channel12a, and respond to a second force and travel away from the weir sealing portion12cto open the weir-type diaphragm valve10and allow fluid flow through the fluid channel12a,a center flexing portion14b,14b′,14b″ off the weir12bconfigured to experience convex and concave flexing extremes when the weir-type diaphragm valve10is closed and opened, andan outer sealing portion14c,14c′,14c″ configured to be fully constrained between components, one of which includes the valve body, when the weir-type diaphragm valve is closed and opened.
The two or more diaphragm portions14a,14b,14c;14a′,14b′,14c′;14a″,14b″,14c″ may be configured with different characteristics based at least partly on different material stresses associated with different functionality that each portion14a,14b,14cis configured to perform when the weir-type diaphragm valve10,10′ is closed and opened.

The various embodiments for implementing the present invention may include one or more of the following:

FIGS.2a,2b: Deviation from Rotational Symmetry

FIGS. 2a,2bshow an embodiment of the weir-type diaphragm valve10, in which the present invention is implemented based at least partly on a deviation from a rotational symmetry, according to some embodiments of the present invention.

For example, the different characteristics may be based at least partly on the shape of the diaphragm weir sealing portion14aat the weir12b. In particular, the shape of the diaphragm weir sealing portion14aat the weir12bmay be configured to match the shape of the weir sealing portion12c. Moreover, the center flexing portion off the weir may also be shaped to reduce stress with inflection, e.g., including shaping the center flexing portion on either side of the weir to reduce resistance to diaphragm inversion. Moreover still, the diaphragm weir sealing portion14amay include a pair of studs14dembedded therein and configured perpendicular to the orientation of the weir12bto initiate inflection with lower stress. Each stud14dis embedded in the diaphragm14so as to be arranged on a respective side of the weir12bwhen the weir-type diaphragm valve is closed. Weir-type diaphragm valves having two such studs like element14dare disclosed in patent application Ser. No. 13/554,535, filed 20 Jul. 2012, entitled “Two-stud Diaphragm for Diaphragm Valve,” (911-002.049-1//F-EV-1201US), which is hereby incorporated by reference in its entirety.

InFIG. 2a, the weir-type diaphragm valve10also includes a backing cushion16, a compressor18and a spindle20, as shown.

The embodiments shown inFIGS. 2aand2bare provided by way of example, and other embodiments or configurations having a deviation from rotational symmetry of the diaphragm14are envisioned that are consistent with the spirit of the present invention, but might otherwise appear visually different than that specifically shown inFIGS. 2aand2b. For example,FIG. 2bshows the diaphragm weir sealing portion14ahaving a pair of studs14dembedded therein and configured perpendicular to the weir12bto initiate inflection with lower stress. However, embodiments are envisioned having three studs with two studs on the high pressure side of the weir12band one stud on the low pressure side of the weir12b; or with two studs on each side of the weir12b. The scope of the invention is also not intended to be limited to any particular distance between the two studs14d.

FIGS.3a,3b: Form a Diaphragm “Free” Shape Between Open and Closed Requirements

FIGS. 3a,3bshow an embodiment for implementing the present invention based at least partly on forming a diaphragm “free” shape between open and closed requirement of the weir-type diaphragm valve, according to some embodiments of the present invention.

For example, the different characteristics may be based at least partly on forming a diaphragm “free” shape between open and closed requirements of the weir-type diaphragm valve14′. By way of example, the diaphragm “free” shape may include, or take the form of, configuring the diaphragm14′ by balancing tensile and compressive material stress extremes during mechanical cycling, which also facilitates easier diaphragm installation with a midway compressor position. InFIG. 3b, the diaphragm weir sealing portion14ais shown having a balloon-like shape or contour, while the center flexing portion14U is shown having a curved portion extending completely around the diaphragm weir sealing portion14a. The outer sealing portion14c′ is shown extending around the center flexing portion14b′.

InFIG. 3a, the weir-type diaphragm valve10′ also includes a backing cushion16′, a compressor18′, a tube nut30and an attachment stud32, as shown.

The embodiments shown inFIGS. 3aand3bare provided by way of example, and other embodiments or configurations having a deviation from rotational symmetry of the diaphragm14are envisioned that are consistent with the spirit of the present invention, but might otherwise appear visually different than that specifically shown inFIGS. 3aand3b. For example, the scope of the invention is not intended to be limited to the specific balloon-like shape or contour of the diaphragm weir sealing portion14ashown inFIG. 3b. Embodiments are envisioned in which the diaphragm weir sealing portion14ahas a different shape than that shown inFIG. 3bthat would still be within the spirit of the present invention. Further, the scope of the invention is not intended to be limited to the specific curved portion of the center flexing portion14U. Embodiments are envisioned in which the center flexing portion14b′ has a different curvature or shape than that shown inFIG. 3bthat would still be within the spirit of the present invention. The embodiments shown inFIGS. 3aand3binclude both the balloon-like shape or contour of the diaphragm weir sealing portion14ain combination with the curved portion of the center flexing portion14b′. However, embodiments are envisioned in which the diaphragm is implemented with only one of these features, but in combination with some other feature disclosed herein within the spirit of the present invention.

FIG.4: Vary the Diaphragm Thickness

FIG. 4shows embodiments for implementing the present invention based at least partly on varying the thickness of a diaphragm14″, according to some embodiments of the present invention.

For example, the different characteristics may be based at least partly on the thickness of the two or more diaphragm portions or areas14a″,14b″,14c″. In particular, the diaphragm weir sealing portion14a″ at the weir may be configured with a weir seal pad or thickened padding14a″(1) which experience minimum bending or flexing. The center flexing portion14b″ off the weir may be configured with thin locations or elastomeric material14b″(1) which require the most bending or flexing during mechanical cycling. The thin locations or elastomeric material14b″(1) may also be configured at least partially around the center flexing portion14b″. Moreover, the center flexing portion14b″ off the weir may be configured with thickened locations14b″(2) in areas of low flexure for increased membrane pressure strength. The thickened locations14b″(2) may be configured at least partially around the center flexing portion14b″. The thin locations or elastomeric material14b″(1) and the thickened locations14b″(2) may also be configured so as to alternate, consistent with that shown inFIG. 4.

Furthermore, a thickened area labeled14a″(2) is configured as a thick portion of the weir seal pad14a″(1) that requires increased sealing pressure between metal components when the weir-type diaphragm valve is closed. InFIG. 4, a shell seal portion or area labeled14c″ is configured beyond the thickened areas14a″(2), as shown.

InFIG. 4, the diaphragm14″ is also shown having an attachment stud32″ arranged therein.

The embodiment shown inFIG. 4are provided by way of example, and other embodiments or configurations having varying thicknesses of the diaphragm14″ are envisioned that are consistent with the spirit of the present invention, but might otherwise appear visually different than that specifically shown inFIG. 4. For example,FIG. 4shows an embodiment having three thin locations14b″(1) and two thick locations14b″(2) that alternate. However, embodiments are envisioned having two thin locations14b″(1) and three thick locations14b″(2) that alternate; or two thin locations14b″(1) and two thick locations14b″(2) that alternate; or three thin locations14b″(1) and three thick locations14b″(2) that alternate; or two thin locations14b″(1) and one thick location14b″(2) inbetween the two thin locations14b″(1); etc. Embodiments are envisioned having some combination of thick and thin locations14b″(2),14b″(1) with or without the thickened sealing area14c″(1) around the periphery; or having some combination of thick and thin locations14b″(2),14b″(1) with or without the thickened padding14a″(1) on the weir sealing portion14a″. Embodiments are envisioned having the thickened padding14a″(1) on the weir sealing portion14a″ in combination with the thickened sealing area14c″(1) around the periphery.

Embodiments are also envisioned within the spirit of the present invention where the location with respect to the weir seal pad14a″(1) may be thinner in order to obtain an optimal seal. The main concept of the present invention is to have local modifications consistent with that disclosed herein to optimize sealing and reduce material stress.

Reduce Weir Bead Height or Eliminate Weir Bead in Areas of Greatest Membrane Inflection

According to some embodiments of the present invention, the diaphragm14,14′,14″ may be configured without a weir bead in areas of greatest membrane inflection, consistent with that shown in relation toFIGS. 2a,2b,3a,3b, and4.

Alternative, according to some embodiments of the present invention, the diaphragm14,14′,14″ may be configured with a substantially reduced weir bead height in areas of greatest membrane inflection. In other words, the substantially reduced weir bead may also be configured on, or in relation to, the diaphragm14,14′,14″ shown inFIGS. 2a,2b,3a,3b, and4.

Different Material Stresses

According to some embodiments of the present invention, and consistent with that shown inFIGS. 2a,2b,3a,3b, and4, the different characteristics may be based at least partly on different material stresses associate with deformations of the two or more diaphragm portions14a,14b,14c;14a,14b′,14c′;14a″,14b″,14c″. For example, the diaphragm weir sealing portion14a,14a,14a″ may have a first physical characteristic based at least partly on one type of diaphragm surface stress at the weir related to the pushing and pulling of the weir sealing portion to and from the weir in order to close and open the weir-type diaphragm valve, and the center flexing portion14b,14b′,14b″ may have a second physical characteristic based at least partly on another type of diaphragm surface stress off the weir related to mechanical cycling of the center flexing portion when opening and closing the weir-type diaphragm valve.

The Scope of the Invention

Finally, the scope of the invention is intended to include embodiments, where a characteristic of one diaphragm portion could be based on a prior art characteristic of the one diaphragm portion, while the other characteristic of the other diaphragm portion could be based on one of the new techniques set forth in the instant patent application. In other words, the scope of the invention is not intended to require that embodiments contain two of the techniques disclosed in the instant patent application be used together. Instead, only the characteristics of the two different diaphragm portions themselves need to be different.