Pumps – Motor driven – Fluid motor
Reexamination Certificate
2002-06-11
2004-02-24
Wolfe, Willis R. (Department: 3747)
Pumps
Motor driven
Fluid motor
C417S063000, C418S002000
Reexamination Certificate
active
06695593
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
This invention relates to components for operation in ultra-pure environments and, more particularly, to novel systems and methods for providing long-lived pumps that are metal-free, ultra-pure, non-reactive, etc. for providing environments for hot, reactive or pure, liquids at elevated temperatures, with respect to ambient.
2. The Relevant Technology
Non-reactivity is a critical function in systems managing, transporting, or relying upon fluids. Fluids include gases and liquids. Many industrial processes rely on liquids, that may damage, weaken, leach, or otherwise interact with metals, elastomeric polymers, and other common materials.
One industry that has suffered with the limited technology available to provide high purity and temperature is the semiconductor processing industry. For example, hot, de-ionized water is used in numerous processes. Impurities are measured in parts per billion. Some materials may be hot acids used in etching and cleaning processes. Transporting, holding, heating, and other procedures for managing ultra-pure water, acids, and the like, are problematic in several ways.
For example, pumps have traditionally been made of metal. Metals are commonly used in the support structures of the pumps. Regardless of the “stainlessness” of a metal, the purity requirements are not met by any known metals.
Polymers are often used for sealing members but may leach, react, degrade, or otherwise contaminate liquids. Moreover, polymers are typically not dimensionally stable. Polymers creep, stretch, yield, and otherwise become unreliable. Polymers (plastics, elastomers) respond to load, pressure, time, chemical environment, and, if any system failure occurs, may destroy any hope of reliability and “failing clean,” failing to function yet leaving no contamination possible. Failures in the sealings may arise by creep or yielding of polymers. Leaks or other failures may expose materials during any failure. Accordingly, seals do not achieve perfect protection. The ability to avoid failures completely ranges from extremely difficult to impossible. Failures can be catastrophic if a system will not “fail clean.”
Contaminants in trace amounts which exceed allowable limits may destroy a batch of product. Physical destruction is not required. Rendering a silicon wafer, or other high purity substrate material, unusable due to contaminant reaction with a surface can waste product output. Down time for decontamination may be even more costly in actual lost production.
What is needed is a fluid handling system that is clean to extremely high standards. All materials that may potentially contact contained fluids, even in the event of failures, should be pure and non-reactive. Materials should tolerate temperatures in the range of 1 degree Celsius to 180 degrees Celsius. In some acids, temperatures may range from 100 degrees Celsius to 180 degrees Celsius.
Thus, stability over a broad range of temperatures, reliability in service, long life under exposure to extreme of temperatures, pressure, and reactive agents, and the like must all be tolerated. Repeatability of designs, and reliable repeatability over the lifetime of all installed apparatus in the system are very desirable. Currently, the most reliable pump mechanisms still depend on elastomeric seals and metal structural supports. Pumps do not have sufficient life and do not “fail clean” in service. Upon failure, metals and elastomers are then exposed and are reactive. Thus, pumps still fail to maintain purity in failure or to operate reliably over many millions of cycles.
What is needed is a reliable, failclean, pump that operates over 10-50 million cycles, and that maintains purity, even in failure. Long term durability at elevated temperatures, pressures, and reactivities, without the threat of catastrophe at failure, is needed.
BRIEF SUMMARY OF THE INVENTION
In view of the foregoing, it is a primary object of the present invention to provide a clean, high temperature, non-reactive, repeatable, producible, reproducible, low-cost, dimensionally stable, long-lived pump.
It is an object of the invention to provide a pump that will tolerate conventional manufacturing processes while providing suitable reliability and low-cost operation and maintenance for routine installations.
It is an object of the invention to provide a pump construction that can rely on readily available materials and readily available manufacturing processes at standard manufacturing tolerances in order to maintain costs while providing reliability over tens of millions of cycles.
It is an object of the invention to provide reliable sealing in a pump, long-lived diaphragms at low cost, and a simple reliable mounting assembly that will support a fluid handling system and which will fail clean in the event of any failure.
Consistent with the foregoing objects, and in accordance with the invention as embodied and broadly described herein, an apparatus and method are disclosed, in suitable detail to enable one of ordinary skill in the art to make and use the invention. In certain embodiments an apparatus and method in accordance with the present invention may include a body and heads holding diaphragms with an associated adaptive seal. A union ring on each head may be provided, to connect to the body and to hold the diaphragm securely.
A pump may be assembled with threads. A union-type connector may hold the body and a head together. In one apparatus and method in accordance with the invention, a polymeric, preferably a fluoropolymer and non-reactive film, may form a diaphragm. The diaphragm maintains a single, substantially constant thickness without the need for changes in cross-section in order to accommodate mounting. The diaphragm may be contoured to fit a chamber so as to match the chamber wall at each end of a stroke. Accordingly, the diaphragm is fully supported when the pump is dead-headed, or backed up in a flooded or shut off position.
As a practical matter, no inflection point is required in the diaphragm during any unconstrained or unattatched point of its traverse. Hardware contact on the diaphragm is not substantial enough to cause overstressing, secondary creep, yielding or the like in the diaphragm.
The diaphragm is extremely reliable such that it becomes non-limiting in the life of the pump. Components close to the diaphragm use tight tolerances, closely matched angles, and short gaps between components. The configuration of the components provides for little unsupported material which reduces the stress within the material. No other loading is applied to the diaphragm. In the event of an air system failure, in an air-actuated pump, the high pressure applied to the diaphragm will be supported by the backing material on a chamber head or piston head. Likewise, since no buckling is required in the diaphragm, there is no change of direction and no inflection point within the chamber during operation. As a result, the life of the pump is greatly extended.
In one embodiment, the frame may be installed using a trapezoidal seal shim that produces a sharp angle bend, preferably less than or equal to 70 degrees. Thus, the diaphragms may be locked into trapezoidal slots, and held in place by trapezoidal shims, all comprising the same class of material, and preferably the exact chemically consistence or chemically identical material. Accordingly, the pump diaphragms limit any need for rim or compression seals, clamps, flanges, elastomeric seals, metals, and the like.
In one embodiment, the trapezoid may be irregular. One side may have a 70 degree angle, 20 degrees less than a right angle, and the other side may be a right angle. In another embodiment the trapezoid is regular and has a 70 degree angle, 20 degrees away from normal or perpendicular. The seal formed in a regular trapezoid becomes self centering.
The diaphragm is retained using no elastomeric materials, no rims, no metals, no flanges, no through-holes, and the like. Furthermore, the diaphragm is subjected to equalized loads. Prior ar
Dunn Michael
Kingsbury David
Orr Troy
Steck Ricky B.
Stillings Matthew
Trebor International, Inc.
Wolfe Willis R.
Workman Nydegger
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