HK1109193B - Anti-cavitation valve assembly - Google Patents

Description

Anti-cavitation valve assembly

Technical Field

The present invention relates generally to controlling valves in high pressure fluid delivery systems. More particularly, the present invention relates to controlling valves having anti-cavitation and low noise properties.

Background

When subjected to high pressure differentials or high flow rates, valves often exhibit excessive noise and vibration. This is generally attributed to the cavitation phenomenon, which can vary from a relatively harmless level known as incipient cavitation to a significantly more severe level that actually damages the valves and associated piping. This can be so great as to cause hearing loss to plant personnel if subjected to cavitation for extended periods of time. If the fluid velocity in the valve seat area becomes too great, causing a sudden and sharp drop in pressure, the fluid is converted into a gaseous state, resulting in the formation of numerous tiny bubbles, creating cavitation. When the pressure increase condition is restored, the seat area velocity then drops and the pressure rises, causing these bubbles to collapse at a rate of many times per second. This may occur near any metal surface and damage may occur. Over time, this can lead to valve failure due to vibration and/or erosion. Minimizing or eliminating these conditions that adversely affect operation and valve life remains one of the most serious challenges encountered in the daily operation of water distribution systems, such as municipal water systems and the like.

To overcome the adverse effects of orifice action (orifice action) of a valve, it is common practice to design the valve such that the flow of fluid through the valve is split into a large number of small streams which are then directed through a convoluted path resulting in an energy loss to the fluid. This design is referred to as bend flow diversion. One example of such a design is described in U.S. patent nos. 4,567,916 to Bates et al; U.S. patent No.4,024,891 to Engle et al; U.S. patent No.4,693,450 to Paetzel et al.

But the device is not optimal for effective noise and cavitation reduction. The most significant disadvantage of this design is the significant reduction in valve capacity, rendering the valve unsuitable for use in some situations. The valve design also requires rather complex and expensive manufacturing and assembly.

Other Valve assemblies are known, such as those produced by Ross Valve Manufacturing company inc, which employ aligned plates for damping vibration, pressure fluctuations, cavitation, and noise. For example, an upstream corrugated plate may be selectively slid into place to control flow. A downstream plate having a plurality of orifices produces a plurality of jets that reduce pressure flow through the set of plates. However, the number and size of the orifices in the plate, the number of plates and their spacing are determined by the flow, and different flows can render such orifice plates ineffective.

Singer Valve inc. provides an anti-cavitation trim component with interconnected cans with multiple small circular orifices that overcomes many of the problems of previous "tortuous path" and "stacked plate" designs. Singer Valve effectively and substantially eliminates noise and cavitation. However, the valve assembly is prone to clogging or clogging due to the canister employing the small circular orifice. In fact, typically the fluid must be filtered before passing through the Singer Valve module. However, as the fluid exits the canister of the singerfalve assembly, the fluid is directed directly toward the chamber walls, causing erosion.

Therefore, there is a continuing need for a valve assembly having anti-cavitation and low noise characteristics and controlling high flow rates. Such a valve assembly should be adjustable so as to control the flow therethrough while optimizing the pressure drop and reducing negative impacts on the inner surfaces of the valve chamber. The present invention fulfills the needs and provides other related advantages.

Disclosure of Invention

The present invention provides a valve assembly that reduces the pressure across the valve and substantially eliminates corrosion and its attendant disadvantages. The valve assembly of the present invention also directs fluid through the valve so that damage caused by other forces, such as fluid flow, is minimized.

In general, the valve assembly of the present invention includes a seat disposed within a chamber located between a fluid inlet and a fluid outlet. The seat includes a wall defining an interior cavity, and a plurality of elongated slots formed in the wall of the seat. In certain preferred embodiments, the seat includes a bottom wall having a circumferential wall extending upwardly and defining an internal cavity. The extension slot is formed in the circumferential seat wall. The elongated slot is preferably formed at a direct angle of about 90 degrees relative to the seat wall to direct fluid toward the center of the seat cavity.

The disc guide is associated with the seat such that the seat and the disc guide slidably move relative to each other. In a particularly preferred embodiment, the seat is fixed to the chamber, for example by a disc guide such as a hydraulic control device moving relative to the seat.

The disc guide includes a wall having a plurality of elongated slots formed therein. In a particularly preferred embodiment, the disc guide comprises a top wall and a circumferential wall extending downwardly from the top wall. The extension groove is formed at an upper portion of the circumferential wall. The elongated slot is preferably formed on the disc guide so as to direct fluid at an indirect angle toward the chamber. Accordingly, the elongated slot is formed in the disc guide at an offset angle other than 90 degrees.

The disc guide top wall is adapted to sealingly engage an upper edge of the seat. The non-slotted lower portion of the circumferential disc guide wall is configured to substantially close the elongated slot of the seat when the disc guide and seat are moved to the closed position.

When the disc guide and seat are moved to the closed position, fluid is prevented from passing from the chamber fluid inlet to the chamber fluid outlet. When the disc guide and seat are moved to the open position, fluid is directed from the chamber fluid inlet, through the seat elongated slot, into the chamber lumen, into the disc guide lumen, and through the disc elongated slot into the chamber fluid outlet, resulting in a reduction in fluid pressure and minimal cavitation.

Other features and advantages of the present invention will become more apparent from the following more detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.

Drawings

The figures illustrate the invention. In the drawings:

FIG. 1 is a cross-sectional perspective view of a valve assembly embodying the present invention with the seat and valve guide in an open position;

FIG. 2 is a partially exploded perspective view of the components of the assembly of the present invention;

FIG. 3 is a cross-sectional schematic view of the valve assembly of the present invention in the closed condition;

FIG. 4 is a cross-sectional schematic view of the valve assembly in an open state;

FIG. 5 is a cross-sectional view of the valve assembly showing liquid flow at an angle from the disc guide to the valve assembly outlet when in the open position.

Detailed Description

As shown in the drawings for purposes of description, the present invention is directed to a valve assembly, generally designated by the reference numeral 10, the assembly 10 of the present invention, as will be more fully described herein, being designed and constructed to reduce the pressure of fluid passing through the valve assembly 10 and substantially eliminate cavitation. The valve assembly 10 of the present invention also directs fluid in such a manner as to minimize erosion damage.

Referring now to fig. 1, a valve assembly 10 includes a body or chamber 12 defining a fluid inlet 14 and a fluid outlet 16. As shown, the fluid inlet 14 and outlet 16 are generally located on opposite sides of the chamber 12. A cover 18 is provided over the chamber 12 and is attached or secured in place using bolts 20 or the like. The chamber 12 and cover 18 define the primary pressure range of the assembly 10, together forming an internal fluid chamber between the inlet 14 and the outlet 16. Since the valve assembly 10 of the present invention is typically used in high pressure environments, such as municipal water supply lines and the like, the body 12 and the cover 18 are made of a durable material, such as cast metal or the like.

The valve assembly 10 of the present invention is particularly designed for use in environments requiring large pressure drops. As discussed above, large pressure drops in the fluid flow can produce cavitation and noise, which can damage valve components.

Referring now to fig. 1 and 2, the valve assembly 10 includes a subassembly 22, often also referred to as a "trim component," which is designed to produce a desired pressure drop through the valve assembly 10 while imparting cavitation and erosion resistance. In particular, the subassembly 22 includes a seat 24 that is a sliding fit with a disk guide 26. As will be described more fully herein, when the seat 24 and disc guide 26 are moved toward one another in the closed position, fluid flow to the outlet 16 of the valve assembly 10 is shut off. However, as the seat 24 and disk guide 26 are gradually moved away from each other into the open position, fluid is permitted to flow from the inlet 14, through the outlet 16 of the assembly 10.

In a particularly preferred embodiment, as shown in fig. 1, 3 and 4, the seat 24 is fixedly attached to the chamber 12, for example by threaded attachment, bolts or any other suitable positioning means. The seat 24 includes a bottom wall 28 and a circumferential wall 30 extending upwardly from the bottom wall to an upper edge or lip 32. The bottom wall 28 and the circumferential wall 30 collectively define a seat cavity 34. As shown, the seat 24 is typically a cylindrical or cylindrical structure, but it is not so limited.

A plurality of elongated slots 36 are formed in the seat peripheral wall 30. These elongated slots are typically formed in the lower portion of base wall 30. Typically, the vertical slots 36 are spaced about the circumferential wall 30. The total open area of the slots 30 is less than the total open area of the valve inlet 14, resulting in a pressure drop across the slot members. In a particularly preferred embodiment, these elongated, perpendicular grooves 36 are formed at a direct, or nearly 90 degree angle relative to the circumferential wall 30 to direct fluid flow from the grooves 36 toward the central portion of the seat cavity 34 such that the fluid flow converges on itself at the central cavity 34 when the valve assembly 10 is opened, as shown in FIG. 4.

The fluid flow is then redirected from the central lumen 34 to the disc guide 26. The disc guide 26, as shown in FIG. 2, includes a top wall 38 having an aperture 40 therethrough for receiving a stem or rod 42. A shoulder 44 is formed on the stem 42 that seats within a boss 46 of the disk guide top wall 38 to interconnect the stem 42 and the disk guide 26.

Referring particularly to FIG. 2, a diaphragm 48, typically composed of an elastomeric material such as rubber or the like, is sandwiched between a disk retaining sword 50 and a diaphragm washer 52. The stem extends between the diaphragm 48, the disk retainer 50 and the diaphragm washer 52. The components 42 and 48-52 are secured together by a nut 54 or other such retaining device that is threadably received within the shank 42. The stem nut 54 is tightened to press the diaphragm washer 52, diaphragm 48 and disk retainer 50 tightly against one another. Thus, in the final assembly 10, the disc guide 26, the stem 42, the spacer 48, the disc retainer 50 and the spacer washer 52 are all interconnected to one another.

With continued reference to fig. 1 and 2, it will be noted that the resilient diaphragm includes a plurality of apertures 56. These apertures 56 are sized and numbered to correspond with the bolts 20 extending through the cover 18 and into the chamber body 12. As shown in fig. 1, the cover 18 includes an aperture or guide slot 58 through which the handle 42 is at least partially vertically movable. The cover support 60 is aligned with the stem 42 to ensure proper vertical movement thereof.

Thus, as the stem 42 moves up and down along a vertical path, the disc guide 26 is moved up and down, away from the seat 24 and into the seat 24. In particular, the disc guide 26 includes a circumferential wall 62 extending downwardly from the top 38 and which is sized and configured to be received within the internal cavity 34 of the seat 24, preferably abutting the circumferential wall 30 of the seat 24. A plurality of elongated vertical slots 64 are formed in the circumferential wall 62 of the disc guide 26. A slot 64 is formed in the upper portion of the wall 62. The lower portion 66 of the circumferential wall 62 is not slotted and is sized so that it substantially completely closes the slot 36 of the seat 24 when the disc guide 26 is fully lowered. This is referred to herein as the "closed" position. When the stem 42 is moved upward, the disc guide 26 is likewise moved upward and away from the seat 24, at least partially exposing the seat recess 36, allowing fluid to pass therethrough.

Referring now to fig. 3 and 4, when fluid is not flowing through the valve assembly 10, the weight of the disc guide 26, stem 42, etc. causes the stem 42 and disc guide 26 to be positioned downwardly within the seat 24 so as to be in the closed position. A spring 68 is disposed between the cover 18 and the diaphragm washer 52 so as to bias the disc guide 26 into the seat 24 in the closed position.

When fluid is present within the valve assembly 10, the fluid pressure is typically sufficient to act upon the resilient diaphragm 48 and move the diaphragm 48, as well as the disc guide 26, stem 42, disc retainer 50, and diaphragm washer 52 upwardly, so as to open the valve assembly 10 and allow fluid to flow therethrough, as shown in FIG. 4. To selectively open or close the valve assembly 10, i.e., the position of the disc guide 26 relative to the seat 24, a hydraulic control device 70 is incorporated into the assembly 10. Such hydraulic controls 70 are well known in the art.

Briefly, a switching valve 72 or the like is selectively opened and closed to introduce fluid into an upper pressure chamber 74 between the cover 18 and the diaphragm gasket 52, as shown in FIG. 3. The increased fluid pressure between the cover 18 and the diaphragm gasket 52 causes the diaphragm gasket 52, and thus the stem 42, diaphragm 48, disk retainer 50, and disk guide 26, to be downward. If sufficient fluid is introduced into pressure chamber 74, disk guide 26 is lowered entirely into seat 24 such that lower portion 66 of disk guide wall 62 closes seat groove 36. This effectively closes seat groove 36 and does not allow fluid to flow therethrough. As an added measure, the outer periphery of the disc guide upper wall 38 and the upper lip 32 of the seat 24 contact each other. The upper wall 38 or lower portion of the disk retainer 50 may include a seal 76, such as a rubber sheet or an O-ring, etc., to form a fluid-tight seal between the seat 24 and the disk guide 26 or disk retainer 50. No fluid is therefore allowed from the fluid inlet 14 to the fluid outlet 16, as shown in fig. 3.

Referring now specifically to FIG. 4, when the hydraulic control valve 72 is closed such that no fluid is introduced into the pressure chamber 74, fluid pressure from the inlet 14 acts on the components of the subassembly 22 to raise the disc guide 26, stem 42, diaphragm 48, disc retainer 50 and diaphragm washer 52 upward. If little or no fluid is introduced into the pressure chamber 74, the disc guide 26 will be moved to its highest point so as to be in the fully open position. Those skilled in the art will appreciate that the hydraulic control device 70 may be modified to control the position of the disc guide 26 relative to the seat 24 between a fully closed position, as shown in fig. 3, and a fully open position, as shown in fig. 4.

Referring now to fig. 4 and 5, as described above, the total opening of the combined slots 36 of the seat 24 is less than the total open area of the valve inlet 14, resulting in a pressure drop. The elongated vertical slot 36 preferably forms a direct angle in the seat wall 30 to facilitate the flow of liquid into the seat cavity 34 so that the fluid converges on itself, as shown by the arrows in fig. 4. In addition to creating a pressure drop, potential cavitation is dispersed within central cavity 34 of seat 24 by fluid convergence and impingement. The fluid is then directed upwardly into the inner chamber 78 of the disc guide 26. Such an internal cavity 78 is defined by the upper wall 38 and the lower circumferential wall 62 of the disc guide 26, as shown in the drawings. The fluid is then directed outwardly through the elongated vertical slots 64 of the disc guide 26 and ultimately through the assembly outlet 16, as shown in fig. 4 and 5. However, the fluid flow is redirected from the seat 24 into the disc guide 26 and creates another pressure drop through the outlet 16.

Typically, the slots 64 of the disc guide 26 and the slots 36 of the seat 24 have approximately equal flow areas or openings. Thus, when the groove 36 and seat 24 are exposed, allowing for increased flow and maintaining a controlled pressure drop, the equal groove members 64 of the disc guide 26 are exposed, allowing for a controlled pressure drop to the valve assembly 10.

Referring now specifically to FIG. 5, if fluid is allowed to flow directly from the disc guide 26 to the inner wall 80 of the chamber 12, erosion may occur over time. The present invention minimizes this erosion by forming an extended vertical slot 64 in the disk guide wall 62 at an indirect or offset angle other than 90 degrees. Since the slots 64 are oriented angularly, as shown in FIG. 5, fluid exiting the disc guide slots 64 is directed to impinge against the inner surface 80 of the pressure range of the turn-around chamber 12. The angular path increases the distance between the groove 64 and the pressure range surface inner wall 80, reducing erosion of the inner surface 80 of the chamber 16.

While a single large pressure drop can create cavitation and noise problems, the present invention employs a combination of a series of small pressure drops through the valve assembly 10. As described above, a first pressure drop is created as the fluid passes through the slots 36 of the seat 24. An additional pressure drop is created as fluid is directed from seat 24 to disc guide 26. An additional pressure drop is created as the fluid exits the disc guide slots 64 at an angle toward the inner surface pressure boundary 80 of the chamber 12. This series of small pressure drops helps to place the fluid to vapor pressure or cavitation conditions, allowing a large total pressure drop to be generated through the main valve assembly 10 without creating damaging cavitation conditions.

The valve assembly 10 of the present invention also optimizes fluid flow through the valve assembly 10 by the elongated vertical slots 36 and 64, which provide a greater flow of liquid without the tendency to clog or plug as in prior art assemblies. However, the fluid is not forced through tortuous paths or complex orifices, grooves, channels, etc. as in prior designs. The valve assembly 10 of the present invention is therefore capable of accommodating the passage of relatively large volumes of fluid and has low noise and anti-cavitation properties.

As described above, another advantage of the present invention is that the use of the angled deflection slots 64 and the disk guide 26 creates a pressure drop and reduces detrimental erosion of the inner pressure surface boundary 80 of the chamber 12. Also, the valve assembly 10 of the present invention is relatively simple in design and easy to manufacture and assemble as a diaphragm actuated control valve assembly.

Although an embodiment has been described in detail for purposes of illustration, various modifications may be made without departing from the scope and spirit of the invention, and the invention is not limited except as by the claims.

Claims (21)

1. A valve assembly for reducing cavitation comprising:

a chamber having a fluid inlet and a fluid outlet;

a seat disposed within the chamber intermediate the fluid inlet and outlet, the seat including a wall defining an internal cavity and a plurality of elongated slots formed in the seat wall; and

the disc guide being associated with the seat such that the seat and the disc guide slidably move relative to each other, the disc guide including a wall defining an internal cavity and a plurality of elongated slots formed in the wall of the disc guide;

wherein the disc guide and seat move to a closed position preventing fluid from passing from the chamber fluid inlet to the chamber fluid outlet; and

wherein the disc guide and seat move to an open position directing fluid from the chamber fluid inlet through the seat elongated slot, into the seat cavity, into the disc guide cavity, and through the disc guide elongated slot into the chamber fluid outlet resulting in a reduction in fluid pressure and minimal cavitation.

2. The assembly of claim 1, wherein the seat is fixed to the chamber and the disk guide moves relative to the seat.

3. The assembly of claim 2, including hydraulic control means for selectively moving the disc guide.

4. The assembly of claim 1, wherein the seat comprises a bottom wall and a circumferential wall, an elongated slot being formed in the circumferential wall.

5. The assembly of claim 1, wherein an elongated slot is formed in the seat wall so as to direct fluid toward the center of the seat cavity.

6. The assembly of claim 5, wherein the elongated slot is formed in the seat wall at an orientation angle of approximately 90 degrees relative to the seat wall.

7. The assembly of claim 1, wherein the disc guide wall includes a non-slotted lower portion configured to substantially enclose the elongated slot of the seat when the disc guide and seat are in the closed position.

8. The assembly of claim 1, wherein the disc guide is adapted to substantially sealingly engage an upper edge of the seat.

9. The assembly of claim 1, wherein the elongated slot is formed in the disk guide wall such that fluid is directed toward the chamber at a non-directional angle.

10. The assembly of claim 9, wherein the elongated slot is formed in the disc guide at an offset angle other than 90 degrees.

11. A valve assembly for reducing cavitation comprising:

a chamber having a fluid inlet and a fluid outlet;

a seat disposed within the chamber between the fluid inlet and outlet, the seat including a bottom wall, a circumferential wall extending upwardly from the bottom wall and defining an internal cavity, and a plurality of elongated slots formed in the seat circumferential wall so as to direct fluid toward a central portion of the seat internal cavity; and

the disc guide being associated with the seat such that the seat and the disc guide slidably move relative to each other, the disc guide including a top wall and a circumferential wall defining an internal cavity, and a plurality of elongated slots formed in an upper portion of the circumferential wall of the disc guide and a non-slotted lower portion configured to substantially close the elongated slots of the seat when the disc guide and the seat are moved to the closed position;

wherein the disc guide and seat move to a closed position preventing fluid from passing from the chamber fluid inlet to the chamber fluid outlet; and

wherein the disc guide and seat move to an open position directing fluid from the chamber fluid inlet through the seat elongated slot, into the seat cavity, into the disc guide cavity, and through the disc guide elongated slot into the chamber fluid outlet resulting in a reduction in fluid pressure and minimal cavitation.

12. The assembly of claim 11, wherein the seat is fixed to the chamber and the disk guide moves relative to the seat.

13. The assembly of claim 12, including a hydraulic control device for selectively moving the disc guide.

14. The assembly of claim 11, wherein the elongated slot is formed in the seat wall at an orientation angle of approximately 90 degrees relative to the seat wall.

15. The assembly of claim 11, wherein the disc guide is adapted to substantially sealingly engage an upper edge of the seat.

16. The assembly of claim 11, wherein the elongated slot is formed in the disk guide wall such that fluid is directed toward the chamber at a non-directional angle.

17. The assembly of claim 16, wherein the elongated slot is formed in the disc guide at an offset angle other than 90 degrees.

18. A valve assembly for reducing cavitation comprising:

a chamber having a fluid inlet and a fluid outlet;

a seat secured within the chamber between the fluid inlet and outlet, the seat including a bottom wall, a circumferential wall extending upwardly from the bottom wall and defining an internal cavity, and a plurality of elongated slots formed in the seat circumferential wall at an orientation angle of approximately 90 degrees relative to the seat wall so as to direct fluid toward a central portion of the seat internal cavity; and

a disc guide in sliding communication with the seat, the disc guide including a top wall and a circumferential wall defining an internal cavity, and a plurality of elongated slots formed in an upper portion of the disc guide circumferential wall so as to direct fluid toward the chamber at a non-directional angle, and a non-slotted lower portion configured to substantially close the elongated slots of the seat when the disc guide and the seat are moved to the closed position;

wherein the disc guide is moved to a closed position preventing fluid from passing from the chamber fluid inlet to the chamber fluid outlet; and

wherein the disc guide is moved to the open position to direct fluid from the chamber fluid inlet through the seat elongated slot, into the seat cavity, into the disc guide cavity, and through the disc guide elongated slot into the chamber fluid outlet such that fluid pressure is reduced and cavitation is minimized.

19. The assembly of claim 18, including a hydraulic control device for selectively moving the disc guide.

20. The assembly of claim 18, wherein the disc guide is adapted to substantially sealingly engage an upper edge of the seat.

21. The assembly of claim 18, wherein the elongated slot is formed in the disc guide at an offset angle other than 90 degrees.