Valves and valve actuation – Fluid actuated or retarded – With mechanical movement between actuator and valve
Reexamination Certificate
2001-05-08
2003-04-15
Mancene, Gene (Department: 3754)
Valves and valve actuation
Fluid actuated or retarded
With mechanical movement between actuator and valve
Reexamination Certificate
active
06547214
ABSTRACT:
BACKGROUND OF INVENTION
Field of the Invention
The present invention relates generally to pneumatic valve actuators and, more particularly, to pneumatic valve actuators utilizing methods and devices for force multiplication in the actuation process.
Pneumatically actuated valves are commonly used to control the flow of fluids where remote operation is desired. Examples include utilization in automated processes and hazardous locations. Pressurized air supplying systems for pneumatic controls are typically limited to a maximum pressure of 80-100 psig. Because of this low pneumatic control pressure, pneumatic valve actuators, and especially those that control high pressure fluids through an associated valve, are typically very large in physical size. The large size is necessary to provide a sufficiently large surface area upon which the pneumatic pressure works to generate the force required to control the flow of fluid through the associated valve. At higher fluid pressures, a proportionally higher force is needed to maintain control.
Typical pneumatic valve actuators consist of single and multiple piston designs. Pneumatic pressure acting on the exposed surface area of the piston(s) determines actuator force. Pneumatic valve actuators, and particularly the larger size actuators, pose problems for system designers of fluid distribution systems. Due to exhaust requirements, space constraints, and other relevant factors, it is greatly desirable to minimize the physical size of these pneumatic valve actuators without reducing their ability to generate actuation force or sacrifice valve performance.
Known actuators are disclosed in U.S. Pat. Nos. 4,684,103; 4,875,404; and 5,253,671 wherein attempts have been made to reduce the actuator's size by utilizing a force multiplication mechanism to enable the generation of high forces relative to actuator size. Although the size of these actuators is somewhat reduced, the reductions in size come with inherent disadvantages. The force multiplying mechanism in each of these actuators consumes a substantially large portion of the actuator size and resultantly limits the overall size reduction permitted of the actuator. Also, the force multiplying mechanism in each of these actuators requires an increase in the number of moving parts within the actuator. These additional moving parts increase actuator complexity and decrease its overall reliability.
U.S. Pat. No. 6,059,259 successfully addresses the above described deficiencies, but is more complex than the present invention which has purposely been developed as a simplified solution to the need for size reduction.
Surround-type lever applications, such as a conical-type lever, have proved helpful, but overall unsuccessful because of strength and flexibility inadequacies. A traditional surround-type disk lever is used by applying an actuating force to one side of the disk proximate an interior or exterior edge to pivot the opposite edge about a fulcrum that is located along the opposite surface of the disk. Such a lever has an actuating benefit of allowing application of the actuating force over a large area. A levering benefit, generic to all lever applications, is accomplished via creation of an output levering force that is a multiple larger than the actuating force. Such efforts have proved unsuccessful for high-pressure, small space, applications because arrangements with sufficient flexibility for surround-type levering do not have the strength or rigidity required to actuate the applicable higher pressure valves. Conversely, levers with sufficient strength and rigidity often do not have the flexibility required to accommodate the configuration changes necessary for surround-type levering.
The arrangement of the present invention has been developed in response to these drawbacks which have been appreciated in the art, and as well to provide further benefits to the user. These enhancements and benefits are described in greater detail herein below with respect to several alternative embodiments of the present invention.
SUMMARY OF INVENTION
The present invention alleviates the drawbacks described above with respect to known pneumatic force multiplication actuator devices by employing a serpentine disk lever that has the strength and flexibility required for high pressure applications. The present invention is disclosed in several embodiments and incorporates beneficial features in addition to those just stated as will be described herein below.
Generally, the present invention provides a disk that is flexible enough to be used as a surround-type lever while also being strong enough to accommodate high force transmission requirements, such as those present in high pressure valve systems. The high strength of the disk is accomplished through using a hard material and a specified shape. An example of an applicable hard material of construction is hardened steel. A preferred shape of the disk is circular, whereby the stresses experienced in the disk during use are endeavored to be evenly distributed throughout the disk. The flexibility requirement of levering with a disk, or surround-type levering, is accomplished by the particular cutting of the disk, which will be described in detail.
Benefits of this disk lever configuration, in addition to substantial strength and flexibility increases, permits a smaller and lighter disk arrangement, conservation of construction material, and increased durability. A smaller sized lever is now possible because of the ability to utilize a much stronger material. A weaker material would necessitate use of a disk of significantly greater dimensions to accommodate equal force requirements. A lighter weight disk is possible in the present invention because of the extraction of material to form the mentioned cuts, or slits. Similar benefits may also be provided, if during original formation of the disk, voids are provided where the cuts and slits have been prescribed. A lighter disk lowers the burden on disk production, disk transportation, and on the incorporating system of the disk. Conservation of material is possible by way of recycling the excess material created during the slit cutting process. In this way, the same amount of disk levers can be created from a lower amount of material. The durability, or robustness of the disk is increased by way of the material used, the disk shape, and the type and configuration of the cuts made in the disk. Each of these aspects contribute to minimizing stress concentrations, as well as withstanding those stresses that are induced during operation.
A particularly preferred utilization of the serpentine disk is as a lever in a valve actuator assembly. The purpose of a valve actuator is to open or close an associated valve. This opening and closing of the valve is typically accomplished by the action of a valve stem. While a spring in the actuator continuously works to force the valve stem toward the fully closed position, the disk lever, when actuated, works against this spring to force the valve stem toward the fully open position.
In one embodiment, the serpentine disk lever of the present invention is manufactured to have an outer, or external, and an inner, or internal, edge. Regarding one exemplary embodiment, when the actuator is in the closed position, the lever takes the form of a traditional disk having a planar, flat shape. The disk is located in the valve actuator housing so that it contacts a piston near its external edge. The location of this contact can be called the actuating location. The disk also contacts the valve stem near its internal edge. The location of this contact can be called the lifting location. Finally, to create a levering system, the disk rests on a fulcrum. The location of the contact between the disk and fulcrum lies somewhere between the actuating and the lifting locations just mentioned. The fulcrum location is preferably located closer to the lifting location and the precise force multiplicating effect of the lever is affected by the exact location of the fulcrum. In operation, a
Cartagena Melvin A.
Howrey Simon Arnold & White , LLP
Mancene Gene
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