Valves and valve actuation – Mechanical movement actuator – Particularly packed or sealed
Reexamination Certificate
2001-01-30
2001-12-25
Shaver, Kevin (Department: 3754)
Valves and valve actuation
Mechanical movement actuator
Particularly packed or sealed
C251S306000, C251S314000
Reexamination Certificate
active
06332600
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to valves and methods for fabricating them and, in a preferred embodiment thereof, more particularly relates to rotary valves, such as “butterfly” valves, and associated valve fabrication methods.
Rotary valves, also commonly referred to as “butterfly” valves, are typically provided with a shut-off disc which is rotationally drivable between open and closed positions about an axis diametrically extending across the interior of a generally annular valve body. In its open position the disc permits fluid flow through the valve body, and when the disc is rotated to its closed position its periphery is brought into operative engagement with an annular seal member, which is part of an annular seal cartridge structure supported by the valve body, to shut off further fluid flow through the valve and piping sections that are suitably secured to opposite sides of its body portion.
Although rotary valves of this general type have been utilized for many years in both fluid throttling and shut-off applications, and have been refined in a variety of manners over this time span, they are still subject to several well-known problems, limitations and disadvantages. For example, rotary valve discs are customarily formed as a segment of a sphere and thus have a rounded peripheral seating surface. Because of this conventional disc configuration it is often difficult to reliably and accurately conform the valve seal to the peripheral disc seating surface without undesirably stretching the seal element to a substantial degree. Due to this geometric seal/seat interface problem the integrity of the seal is often compromised and it is difficult to completely stop the flow of fluid through the valve.
Because the periphery of the disc is used as the seal contact surface for the valve, it is critical to proper seal performance that the disc be precisely centered within the valve body. To this end, various structures have been incorporated into conventional rotary valve assemblies to permit the installed disc to be adjusted within the valve body in a manner effecting this necessary disc centering. This centering adjustment, of course, must be carefully and accurately performed to achieve the desired sealing effectiveness. Adjustment error, on the other hand, can seriously reduce the valve's sealing efficiency.
Another limitation present in rotary valves of conventional construction is related to the manner in which an actuator, a motorized device used to forcibly rotate the closure disc between its open and closed positions, is operatively mounted on the valve. In rotary valves of conventional construction an actuator base structure is formed integrally with the valve body (or permanently secured to as by welding) and projects radially outwardly from the valve body. In order to mount an actuator on the valve, an adapter structure is interposed between the actuator and the outwardly projecting base structure and secured to the actuator and base structure. This overall adapter mounting structure undesirably adds to the construction cost of the overall valve assembly and makes the fabrication of the assembly more complex and time-consuming.
As can readily be seen from the foregoing, a need exists for an improved rotary valve assembly, and associated fabrication methods therefor, which eliminate or at least substantially reduce the above-mentioned problems, limitations and disadvantages typically associated with rotary valves of conventional construction as generally described above. It is to this need that the present invention is directed.
SUMMARY OF THE INVENTION
In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, a specially designed rotary valve is provided which includes a valve body and a seal structure, carried by the valve body, for forming an elliptical seating surface. A disc is rotatably carried by the valve body and has an elliptical periphery rotatable into and out of sealing engagement with the seating surface. The elliptical disc periphery has a conical shape which creates an entrance angle on the disc seating surface that provides a variety of operational benefits including a reduction in the torque required to seat and unseat the valve disc from the associated seal structure, and a reduction in the wear on both the disc periphery and the seal seating surface. Due to the reduced operational torque requirements, the parts carrying the actuation load may be smaller, and a smaller valve actuator may be used to seat and unseat the valve disc against the associated seal seating surface. Further, broader manufacturing tolerances may be utilized in conjunction with the disc and seal structures due to a wedging effect provided by the elliptical seal and disc design.
In a preferred embodiment of the rotary valve, the seal structure includes facing annular seal cartridge members, and a resilient annular seal member, representatively a Teflon seal, which is sandwiched between the facing seal cartridge members. An elliptical cavity is formed between the cartridge members and receives a portion of the seal member in a manner deforming it to and holding it in an elliptical configuration, with a radially inner annular portion of the seal member protruding from the seal cartridge members into the valve body interior for operative sealing engagement by the disc periphery. In an alternate embodiment of the rotary valve, the seal member received in the elliptical seal cavity between the seal cartridge members is of a metal material.
According to another feature of the invention, the elliptical seal cavity is formed in at least one of the facing annular seal cartridge members by resiliently deforming the originally circular cartridge member to an elliptical shape and holding the deformed cartridge member in such elliptical shape while at least a portion of the seal cavity is formed on a side of the cartridge member in a circular pattern circumscribing its central axis. The elliptically deformed cartridge member is then released, to thereby permit it to return to its original circular shape. This, in turn, deforms the originally circular seal cavity portion to an elliptical shape conforming to the elliptical shape of the disc periphery.
In accordance with another aspect of the invention, the disc is precisely centered within the valve body, and with respect to the seal structure, in automatic response to installation of the disc within the valve body using two guide members which are inserted inwardly through suitable openings in diametrically opposite flat portions on the outer periphery of the valve body which representatively has an annular configuration.
Portions of the inserted guide members have abutment portions which are brought into contact with corresponding abutment portions on the disc to automatically center it within the valve body. The positions of the abutment portions on the inserted parts of the guide members are precisely controlled by external flange portions on the guide members which abut the diametrically opposite flat portions on the exterior periphery of the valve body. Illustratively, an inner end of one of the guide members is rotatably received in a mounting structure carried on the disc, and a longitudinal portion of a disc-rotating shaft is rotatably extended through the other guide member and is rotationally locked to the mounting portion of the disc.
According to yet another feature of the present invention, a specially designed actuator support structure is secured to the valve body and substantially simplifies and reduces the cost of operatively coupling a motor-driven actuator to the outwardly projecting portion of the disc-rotating shaft. Illustratively, the actuator support structure is of a one-piece construction, is removably secured to the valve body, and is directly connectable to a selected actuator without the conventional necessity of an intermediate adapter structure interconnected between the actuator support structure and the actuator.
Represe
Keasel Eric
Konneker & Smith P.C.
Shaver Kevin
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