Fluid handling – With repair – tapping – assembly – or disassembly means – Assembling or disassembling rotary valve
Reexamination Certificate
2002-03-21
2004-06-15
Walton, George L. (Department: 3753)
Fluid handling
With repair, tapping, assembly, or disassembly means
Assembling or disassembling rotary valve
C137S315220, C403S337000, C403S373000
Reexamination Certificate
active
06748967
ABSTRACT:
FIELD OF THE INVENTION
This disclosure concerns an invention relating generally to components for mechanized/automated actuation of valves, and more specifically to components for coupling valves to pneumatic, hydraulic, electromagnetic, or other forms of actuators whereby the valves may be remotely actuated.
BACKGROUND OF THE INVENTION
Manually-actuated valves, which are actuated by grasping their handles and rotating them to turn their valve stems and thereby modify fluid flow through the valve, are well known. It is often desirable to modify manually-actuated valves so that they may be remotely or automatically actuated by some type of industrial actuator, e.g., a pneumatic actuator, hydraulic actuator, electromagnetic actuator, or other form of actuator providing a rotary input. When valves are modified in this manner, the valve handle is removed from the valve stem, and the valve stem is then connected to an actuator shaft, or to a transmission shaft extending between the actuator shaft and valve stem. The actuators are generally small components with trailing hoses or wires, and they need to be anchored to some portion of the valve or its environment so that rotation of the actuator shaft provides a positive torque input to the valve. Without such anchoring, rotation of the actuator shaft will merely cause the actuator to spin about the valve stem when it is actuated. Rather than building some form of expensive and space-consuming supporting framework which affixes the actuator to the valve's environment, it is usually preferable to somehow affix the housing of the actuator to the housing of the valve so that the actuator and valve are held in fixed relation when the actuator shaft communicates torque to the valve stem.
However, problems commonly arise when attempts are made to couple actuators to valves in this manner. Valves are generally not specifically designed for coupling to valves, and they have a wide variety of sizes and shapes, making it difficult to develop an off-the-shelf coupling solution. Actuators generally do not have such a wide variety of possible configurations and are thus less problematic than valves, but they are nonetheless problematic as well. The actuator and valve housings can sometimes be welded together (or a bridge can be welded therebetween), or other permanent forms of affixation can be used, but these measures are not preferred because of the difficulty in later repair and replacement of the valve and/or the actuator, and also because of the potential damage that may occur to most common actuators if welding is used.
The step that is most commonly taken to achieve a removable affixation between an actuator and a valve is to provide a structure generically known as a “coupler” between the actuator and the valve, with the coupler being configured to join certain categories of valves to certain categories of actuators and serve as a bridge therebetween. Examples of couplers of this nature are seen in U.S. Pat. No. 4,633,897 to Effenberger, 4,719,939 to Killian, U.S. Pat. No. 4,887,634 to Killian, U.S. Pat. No. 5,240,030 to Wang, U.S. Pat. No. 5,564,461 to Raymond, Jr. et al., U.S. Pat. No. 5,634,486 to Hatting et al., U.S. Pat. No. 5,927,682 to Gul et al., U.S. Pat. No. 5,954,088 to Huang, U.S. Pat. No.6,135,417 to Wadsworth et al. and Japanese Patent No. JP406066327A to Yabanetta.
However, these couplers are subject to several disadvantages. First, a coupler's primary goal is to rigidly fix the valve housing with respect to the actuator housing, while mechanically linking the valve stem to the actuator shaft to allow torque transmittal. However, the attachment of the valve and actuator housings often tends to cause problems with torque transmittal because it introduces misalignment between the axes of the valve stem and actuator shaft. If any eccentricity and/or pitch is present between the axes of the valve stem and actuator shaft, the components will experience significant stress and will quickly wear with repeated actuation. Even where couplers have been specifically designed to join particular makes and models of valves and actuators, this misalignment can occur owing to imprecision in aligning the valve stem and actuator shaft. Such imprecision is amplified by imprecisions in valve manufacture, since common valves are manufactured with a surprisingly high degree of variability from valve to valve, thus making it difficult for one coupler to properly fit all valves. For example, it is not uncommon to see variances of up to 5 degrees or more, as measured between the mounting plate of a valve and its valve stem, between the valve stem axes of different valves in a manufacturing run. This variability does not reflect poor quality manufacture, but rather reflects that the valve was intended for manual actuation and flow control. Thus, once the valve packings are installed so that proper valve performance is attained, the valve is suitable for use, and there is no need for its manufacturer to concentrate on its appearance, or its uniformity with other valves in the manufacturing run (or risk the valve's performance by attempting to improve these features). Since the valve will (presumably) be manually actuated, and manual actuation can readily accommodate any irregularity in valve stem orientation, such irregularity is not an important issue—unless the valve is modified for automatic actuation.
Second, where bolt holes are provided on valves and actuators for mounting, the bolt hole placement tends to be different between different manufacturers, makes, and models (though some standard hole placements exist for actuators). Thus, different couplers with different bolt hole placements are needed for each possible valve/actuator combination.
Third, most prior couplers introduce substantial space between the valve and actuator. This is generally necessary so that the coupler can be properly mounted between the valve and actuator, though it can sometimes be useful to allow a flexible transmission shaft to be inserted between the valve stem and actuator shaft to relieve the stress caused by misalignment of their axes. However, the increased space required by these couplers can be undesirable since actuators and couplers must often work in conditions of limited space.
To overcome the foregoing problems, the approach most commonly taken is to take a piece of rectangular tubing, drill holes in its opposing sides which are suitable to allow affixation of the valve and actuator to the opposite sides, and then machine a central shaft/stem bore between the opposing sides so that the actuator shaft, valve stem, and/or transmission shaft can extend between the valve and actuator within the shaft/stem bore. A coupler somewhat similar to this arrangement is seen in U.S. Pat. No. 4,633,897. Since each coupler is custom-made, it is naturally compatible with whatever proposed valve and actuator configurations are in issue, and its maker can fashion it so that it readily accommodates any manufacturing irregularities. However, it is inconvenient to have to rely on the custom generation of couplers each time one is desired. Custom generation is time-consuming, and requires that one maintain an inventory of rectangular tube stock for use in making couplers.
Thus, it would be desirable to have couplers available which do not require custom manufacture, and which may simply be pulled off the shelf to accommodate whatever valve and actuator pair that is proposed for coupling. Ideally, such a coupler would be compact and would not space the actuator so far away from the valve that use of the coupler in confined environments is effectively precluded. Additionally, it would be useful if such a coupler would at least partially compensate for the problem of shaft misalignment between the valve stem and actuator shaft, and the stress and wear that such misalignment can cause on the actuator and valve.
SUMMARY OF THE INVENTION
The invention involves a coupler which is intended to at least partially solve the aforementioned problems. To give the reader a basi
DeWitt Ross & Stevens S.C.
Fieschko, Esq. Craig A.
Uniplex Corporation
Walton George L.
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