Fluid handling – With cleaner – lubrication added to fluid or liquid sealing... – Cleaning or steam sterilizing
Reexamination Certificate
2002-10-08
2003-10-28
Walton, George L. (Department: 3753)
Fluid handling
With cleaner, lubrication added to fluid or liquid sealing...
Cleaning or steam sterilizing
C015S104050, C015S104160, C137S625300, C137S625370, C251S205000, C251S324000
Reexamination Certificate
active
06637452
ABSTRACT:
BACKGROUND
1. Technical Field
An improved fluid valve system is disclosed. More specifically, an improved valve is disclosed which includes a valve plug that is slidably received within a bore defined by a cage. A seal ring is connected to the cage and engagement with the valve plug against the seal ring closes the valve. The valve plug is equipped with a wiper seal that cleans the trim set of debris and residue each time the valve moves between opened and closed positions. As a result, the valve is equipped with a self-cleaning trim set.
2. Background of the Related Art
Valves are commonly used to control the flow characteristics of a fluid. A conventional valve includes a valve body defining an inlet, an outlet, and a fluid flow path extending between the inlet and the outlet. A throttling element, such as a plug, is disposed in the path to control fluid flow. A stem connects the valve plug to an actuator, which moves the valve plug into and out of the flow path. A conventional valve may include a cage extending across the fluid flow path and having orifices formed therein. The plug has an outer surface sized to closely fit an inner wall of the cage. As a result, the plug is slidable inside the cage between a closed position, in which the plug obstructs the orifices, and an open position, in which the plug is clear of at least a portion of the orifices. The plug can also be positioned between fully open and closed positions to control the flow rate of fluid through the cage.
To effect a seal between the plug and the cage, a seal ring can be disposed at the upstream end of the cage. The seal ring can provide a seating surface for a seat disposed at a distal or upstream end of the valve plug. The combination of the seat on the valve plug and the seating surface on the seal ring define what is known as the trim set for the valve. One problem associated with currently available valve systems is that the fluid flowing to the valve can contain abrasive particles and fluids that can crystallize during pressure reduction. These particles and crystals can cause premature wear to the trim set or adversely affect the valves ability to seal properly. While some valve systems incorporate so-called wiper seals to clean the valve trim, these known wiper seal systems do not clean the valve trim immediately before and after sealing. Further, known wiper seals do not protect the seating surfaces from being exposed to fluid flow as the valve is initially opened. As a result, the seating services are exposed to high pressure flow which, as discussed above, can contain abrasive particles and crystals resulting in premature seating surface wear.
As a result, there is a need for an improved valve system with a self-cleaning mechanism to clean the valve trim and further to protect the seating surfaces from initial fluid flow during the opening of the valve or the initial throttling of the valve.
SUMMARY OF THE DISCLOSURE
An improved valve system is disclosed which comprises a cage defining a bore extending along an axis. A plug is sized to fit within the bore and is adapted for slidable movement along the bore axis between closed or opened positions. The plug comprises a proximal end or downstream connected to a valve stem and a distal or upstream end. The plug further comprises a seat disposed between the proximal and distal ends thereof. The valve further comprises a seal ring disposed between the distal end of the plug and the cage when the plug is in the closed or sealed position. The seal ring comprises a seating surface for engaging the seat of the plug when the plug is in the closed position. The plug further comprises a wiper seal disposed between the seat and the distal end thereof. The wiper seal comprises an outside surface adapted to engage the interior surface of the cage and the seating surface of the sealing ring as the plug is moved between closed and throttle positions.
As a result of its placement between the seat and the distal end of the plug, the wiper seal engages the seating surface before the seat as the plug is moved from a throttle to a sealed position. Further, as the seat of the plug is moved off of the seating surface as the plug is moved from the sealed to a throttle position, the wiper seal again engages the seating surface and, further, engages a remaining portion of the seal ring and further engages a distal or upstream end of the cage before the plug reaches an initial throttle position. As a result, the wiper seal cleans the seating surface and the upstream portion of the cage when the plug is moved from a throttling to a sealed position and further when the plug is moved from a sealed position to an initial throttling position.
In a refinement, the wiper seal comprises a material sufficiently rigid to scrape foreign material from the seating surface as the plug moves in either axially direction and further the material of the wiper seal is sufficiently resilient to minimize damage to the seating surface of the sealing ring and the interior surface of the cage.
In a further refinement, the wiper seal comprises poly(etheretherketone) (PEEK) or another suitable high performance plastic such as ultra-high molecular weight polyethylene (UHMWPE).
In another refinement, the wiper seal is an elastic seal that is biased radially outwardly to provide good engagement between the wiper seal and the seating surface as well as the interior surface of the cage.
In another refinement, the wiper seal comprises two spaced-apart wiper seals, both disposed between the seat of the plug and the distal end or upstream end of the plug. One or both of the seals can be fabricated from PEEK and one or both of the seals can be a spring-biased metallic seal. In a further refinement, the upper seal is made from PEEK and the lower seal is the spring-biased metallic seal. One or both of the seals could also be fabricated from UHMWPE.
In yet another refinement, the plug further comprises a plastic or “soft-seat” seal disposed between the wiper seal and the seat. The soft-seat seal may be accommodated in a common groove with the wiper seal or, the soft-seat seal may be disposed in a separate groove disposed between the wiper seal and the seat of the plug.
Other features and advantages of the disclosed valves and wiper seals will become apparent to those skilled in the art from the following detailed description and accompanying drawings.
REFERENCES:
patent: 1199350 (1916-09-01), Collin
patent: 2341018 (1944-02-01), Clapp
patent: 3352316 (1967-11-01), Zahn
patent: 3658083 (1972-04-01), Fetterolf et al.
patent: 3716069 (1973-02-01), Reynolds
patent: 3722854 (1973-03-01), Parola
patent: 4041982 (1977-08-01), Lindner
patent: 4617963 (1986-10-01), Stares
patent: 5236014 (1993-08-01), Buls et al.
patent: 5381818 (1995-01-01), Nendzig et al.
patent: 6382253 (2002-05-01), McCarty et al.
Fisher Controls International Inc.
Marshall & Gerstein & Borun LLP
Walton George L.
LandOfFree
Valve with self-cleaning trim does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Valve with self-cleaning trim, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Valve with self-cleaning trim will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3116107