Fiber optic system for detecting pump cycles

A fiber optic system for detecting a stroke of a pump, the fiber optic system including a first fiber optic line configured for directing light onto a portion of the pump that moves during the stroke of the pump. The system further includes a second fiber optic line configured for receiving light that has been transmitted from the first fiber optic line and reflected by the portion of the pump, wherein receipt of the light by the second fiber optic line occurs at a specified point during the stroke of the pump. The moving portion of the pump may be the diaphragm, the reciprocating portion, or any other part of the pump that cycles at regular intervals as the pump operates.

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 art systems dealing with elastomeric materials will not fail clean. Moreover, creep is a factor in all fluoropolymers. However, geometries that can creep are adapted to conform to the seal, forming a tight mechanically adhesive load between the shim, the diaphragm, and the receiver slot for the shim.

A design after this mode prevents creation of diaphragm flange material that would pull in and increase diaphragm arc length. Increasing the diaphragm arc length tends to cause buckling or diaphragm roll at the point of flexure or the point of maximum flexure near the outer most confines of the chamber in which the diaphragm is located. Thus, even thin films of less than or equal to 30 thousands inch may be operated without buckling. Therefore, folding of the diaphragm and premature rupture of the diaphragm is avoided.

In one embodiment, a union nut is used to secure the head of the pump to the pump body or pump frame. A union nut is a slip ring having an aperture allowing the head to protrude there through away from the pump frame or pump body. The head may thus be registered, and the nut is fully free to slip circumferentially while loading the head longitudinally along the access of the driving rod between the pistons and diaphragms of the pump.

A non-reactive material, preferably a polypropylene is used to construct the entire nut. The nut applies a load to a cantilevered edge or lip of the head. Accordingly, primary creep is allowed to occur and loaded out. Thereafter, the head maintains sufficient spring properties, along with sufficient deflection under such spring properties, to maintain the minimum required loading of the head against the pump body at all times of service.

Moreover, the creep losses of thread materials and of the cantilevered head combine to permit less deflection than that required to maintain the spring loads in spite of continuing secondary creep. Therefore, head loading is maintained. The seal surface remains loaded and sealing. Pneumatic loading on the heads during actuation of the pump diaphragms is ineffective to cause excessive creep and unload the heads. Moreover, weeping, releasing chemicals, is eliminated. Moreover, compliant elastomeric seals are not required to act as energizers. Again, such a sealing system provides for a “fail-clean” failure in the event of any potential failure.

In one embodiment, the heads of the pump may be provided with leak detectors. The leak detectors may be sealed away from the fluid of the pump by a window. The window is constructed of “non-reactive” material that allows light to transmit.

In one embodiment, a thin diaphragm may be formed of polytetrafluoretheyne. In one embodiment, an anisotropic polymer is used. Moreover, in one embodiment, an expanded PTFE may be used.

Other plastics such as PFA may be used. Nevertheless, PTFE has been shown to be most effective. Moreover, by forming the diaphragm of PTFE, an amorphous fluoropolymer, a flexible diaphragm making a mechanically hermetic seal with the pump body and head (trapezoidal slot and shim) is so effective in practice that in certain circumstances minimal to no loading of the seal is required after a certain period of operational time.

Creep is ever present with fluoropolymers. Accordingly, threads creeping is typical when in tension and shrinking when in compression. Creep and shrinking presents a continuing problem in the use of fluorocarbons. In one embodiment, an entire pump may be assembled, with the lip on the edge of a head retained in an engagement portion of a slip ring or union nut threaded to the body of the pump.

Accordingly, creep will ensue in all components, the body, the cantilevered head portion and the slip ring or union nut. However, heat soaking and below ambient cooling under load may remove primary creep. Thereafter, the nut or union nut may be retightened on each end of the pump, maintaining dimensions within tolerances required for loading. Thus, secondary creep occurring after a heat soak and cooling cycle and loading of primary creep, is insufficient to unload the cantilevered member of the head, and thus maintains the head against the body in sealing relation.

A pump made in accordance with the invention improves operations substantially by including no metallic parts and no elastomeric parts. That is, an apparatus in accordance with the invention, is intended to “fail clean.” To fail clean signifies that a failure of any component within the pump, including any sealing component, results in no contamination of any liquids by reactive materials. Reactive materials include elastomeric polymers such as Neoprene™, Viton™, Nitrile, FKM, EPDM and the like. Other reactive materials include virtually all metals. Although some metals are considered non reactive, the requirements for the purity of liquids used in the semi-conductor processing industry is so strict that even “nonreactive” metals must be considered reactive in so far that the invention is concerned.

Thus, valves in the apparatus made in accordance with the invention contain no reactive components. Two types of strike valves or end-of-stroke valves are contemplated. In one embodiment, a short-stroke valve or poppet valve may operate at the end of a stroke of a diaphragm. The diaphragm, upon reaching the limits of the displacement permitted by a head portion of the operating cavity, contacts the head dome or cavity. Accordingly, a protrusion or post on a poppet valve is contacted by the diaphragm. The poppet valve opens a channel (air channel) to communicate with the now-evacuated head chamber over the diaphragm. The poppet valve, it's actuator with a post integrally formed therewith, and a seat securable, such as threadable, to the head, may be provided.

In another embodiment, a long valve may be adapted to access the end of a stroke of a diaphragm or piston retreating away from the head and toward the body of a pump in accordance with the invention. A long-stroke, pilot valve may be designed to operate as a spool. Accordingly, a shank or shaft of the long-valve may be provided with a bumper maintained in contact with a diaphragm, such as against a diaphragm over an underlying piston head driving and being driven by the diaphragm.

The spool shaft, shank, tang, etc. thus extends into the chamber until the piston and diaphragm are halted by stops. Thereafter, chamber pressure may bleed through ports in the pilot valve to shift operation of the pump, by reversing the stroke. The spools may be designed as known in the art to use the main shaft, having a circumferentially extending channel, with cylindrical bearings passing over ports. Accordingly, bearings may selectively expose ports to circumferential channels, thus altering a position of the spool and subsequent channeling of flows between ports in a main housing surrounding the spool.

In one embodiment, only machined surfaces of nonreactive materials act as sealing surfaces. Additional wear may occur due to a lack of hardness, durability, abrasive-resistance, and the like. Nevertheless, nonreactive polymers maintain low core frictions with one another in certain embodiments. Moreover, any particulates from galling, wear, abrasion, fretting, and the like will nevertheless remain nonreactive. Accordingly, filters and traps within flow lines may typically remove such particulates, and the presence of such particulates will not cause leaching of contaminating ions into pumped fluids.

In one embodiment, no elastomeric seals are used in any valve, including principal check valves checking against back flows into the double chambers of the pump. Machined surfaces serve as sealing surfaces, and relief or clearance is provided in each circumstance where needed in order to maintain loads, tolerate secondary creep, following heat soaking primary creep out, such that loading and deflection requirements for sealing are maintained.

Metal springs are used in certain devices. Likewise, elastomeric seals, such as face seals or “O” rings and the like are often used in prior art systems to form seals. Downtime, lost processing batches, and the like are very expensive propositions. Accordingly, a fail clean system made in accordance with the invention relies on no metal springs, no metal washers, no metal retainers, and no metal of any kind. The fail clean system further does not rely on reactive, or organic materials exposed to operating fluids (gases, air) nor the transferred fluids (DI water, acids, hot acids, etc.). Any possible contact between the air chamber, or the liquid chamber in the pump (of which the pump has two of each, typically) eliminates all contact even in the air chamber with metals and elastomers.

In one embodiment of an apparatus and method in accordance with the invention, a base mounting system may be used for integrating a controller with a pump. Air controllers may be external and may be remote from a pump. However, mounting a pump is often problematic. Accordingly, a base is provided in which fluid conduits of the pump are formed to become the legs connecting a pump for mechanical support to a base. Meanwhile, the entire air controller mechanism may be formed in the base. Alternatively, the base may simply pass air through the pump from an external controller, depending on a users selection.

Several types of air control systems exist. A recirculating air system does not use high pressure. A high duty cycle is typical. Duty cycles bordering on 100 percent over many days may exist. Such a recirculating control system may operate non-stop indefinitely. An external control apparatus relies on a third party to connect a speed control to a pump installation. The third-party speed control dictates the amount of air flow to actuate a pump. Accordingly, reducing volume or pressure of incoming, driving air can be used to decrease the speed of operation of the pump. Thus, decreased displacement may be obtained directly by an external control.

A third type of control module may be a distribution unit. A distribution unit may operate under control of controlling mechanisms within the base. However, as a distribution unit, a pump in accordance with the invention may be dead-headed against a closed line. Thus, the entire pressure of the pump may be brought to bare against the pump and conduit system. A modular air pump may be made externally removable. However, a mount in accordance with the invention may be used for either recirculating air, external air vented to atmosphere after actuation of a cycle of the pump operation, or a distribution unit in which air is recirculated but the pump may be dead-headed against a closed line. A mount may provide a platform adapted to a universal pump. Adapted to different bases for control schemes.

By providing the opportunity for an external air system to mount to the base, the air logic transfer passages may be connected to the pump body directly from the external control system without the use of elastomeric seals. The base is symmetric about its air logic porting. One may note that externally controlled systems theoretically produce no contaminates that could be received into a system. Nevertheless, the pump in accordance with the invention is provided with rapid discharge of all controlling air overboard.

The air logic system is isolated, on the one hand, from the pump, on the other hand, the air logic and air connection system is easily removable and serviceable. Moreover, a clamping block may be inserted laterally into the base, to be locked against the base, maintaining the pump in position. The logic and connection system are easily serviceable in such a package, especially when provided with quick-release capability. Likewise, fluid systems need not be opened in order to conduct air system repairs or service. Since the material in the lines and the pump chambers for liquid is ultra pure, elimination of any possible contact of elastomers, metals, or the like.

A spool valve actuated by a pilot valve detecting the end of a stroke of a diaphragm may be implemented to control the speed and the return of a piston driving or being driven by a diaphragm. However, spool valves may be somewhat treacherous. Spool valves typically receive a signal from one line, and they try to equilibrate that signal at some point. For example, at the end of a stroke, the pilot valve cannot move, and air ported through the pilot valve accumulates in a location. As the pressure in a specific location rises, it may act in an axial direction (transversely with respect to an axis of the driving shaft on the pistons) to shift the position of the spool or shuttle. Stabilizing shifting pressure at a specific location has traditionally been difficult.

A detent or bias mechanism may be implemented in accordance with the invention. Previous diaphragms have typically been frameloaded. For example, in flange-mounted diaphragms, a widely varying range of pressures results in shifting a spool or shuttle. Overcoming friction and the like may provide unreliable forces. In an apparatus and method in accordance with the invention, a snap disk is positioned to a collar and shaft of a spool. A disk is maintained in a cavity restricting the diameter thereof. Nevertheless, longitudinally, with respect to the shuttle or spool, the detent is free to move.

The detent is free to move axially, with respect to the spool or shuttle within a gap freely. However, the detent must break over a center in order to change position between a first biased position deflected in a first direction and a second biased position deflected in a second opposite direction axially with respect to the spool. Moreover, the detent may be made of a particularly stiff material rather than a softer, more flexible elastomeric material. The effect of the more rigid, stiff, radially-constrained, axially-free bias detent is to provide a strict, digital motion of the spool at a narrowly repeatable pressure change.

In keeping with a virtually absolute prohibition against a metallic or otherwise reactive materials in the air path and the liquid path of a pump in accordance with the invention, a rapid exhaust valve is provided. Again, rather than common elastomeric materials, a thin, comparatively rigid, stiff film is provided. A disk of the film may be on the order of less than 0.010 inches in thickness. The dump valve or quick exhaust valve is included to divert rather than return controlled air.

For example, a circulating air control is returned to a prime mover. However, external control systems use ambient air, that is discharged after one use. Thus, a plastic disk is provided that deflects to permit passage of air around it's exterior perimeter and yet to close down against a port at near the center thereof and on the opposite side thereof in response to an airflow in the opposite direction. Thus, a very rapid dump around the exterior parameter of the disk may be conducted, yet no back flow into the lines can occur at any significant rate or total amount.

In one embodiment, a chamber holds the disk. The disk is supported on a grid on one side with fluted walls providing a standoff distance between the outer most radius of the disk and the outer most radius of the containing chamber. Accordingly, air may pass around the disk. The disk is mounted to press against a face of a port occupying an area very near the center of the disk on one side. During venting, air may pass out of the port against the disk, deflecting the disk and passing around the outermost circumference of the disk. By contrast, any pressure of air against the disk from an opposite side nearly forces the entire disk back against the port, scaling the port off against backflow.

A leak detection scheme may rely on fiber optics. In one embodiment, the leak detectors may include a body containing fiber optic lines disposed at an angle calculated to produce reflection of a beam from one fiber optic line to a receiving, second, fiber optic line, only in the presence of liquids. The difference in refractive indices of air and liquids common to processing in the semiconductor industry is sufficient to detect the presence of liquids in the air chamber actuating the piston.

In on embodiment, the fiber optic lines may be sealed against liquids for direct contact with the chamber of the pump. In another embodiment, a separate window may be provided having a very thin thickness, and formed of a material that is like-wise non-metallic, high-purity, non-electrical, nonreactive, and sealed. In such an embodiment, an acrylic fiber may be used. Acrylic fibers will absorb more deflection during handling.

By contrast, fiber optics may tend to break when mishandled, such as by being bent on too tight a radius. It is important to protect operators from being sprayed by exhaust or by controller exhaust when an external controller is used to operate a pump in accordance with the invention. In such an environment, a chamber filled with fluid, may be evacuated by the continuing operation of an external controller, unresponsive to the leak. In one presently preferred embodiment, a window completely seals the chamber from the leak detector, as an acrylic, fiber optic line may be used.

The double-line design is superior to prior art systems and other technologies wherein fiber optic lines are laid side-by-side in order to cooperatively send and receive a beam. The difficulty with such embodiments often includes an inability to define a digital location at which reflected light intensity indicates either a liquid is present or that an end of stroke of the pump has been reached. By using off-axis orientations between the sending and receiving fibers, the index of refraction or the presence of a film layer creates a dramatic, even digital demarcation between a desired condition and an undesired condition.

In one embodiment, a leak detector may be located near an outer circumference of a chamber in which a diaphragm is operating. In such an embodiment, another leak detector may be positioned centrally or elsewhere within an air chamber in order to identify an end of a stroke by the pump. Accordingly, an external controller may use a fiber optic detector for the end of the stroke of the diaphragm of the pump.

For example, as in parallel lines that become retroreflective, a pre-determined angle may be established between two, separate, cooperative fiber optic lines. The difficulty of establishing a value or trigger lever for the reflected light from a sending fiber to a receiving fiber is eliminated by the construction in accordance with the invention. Rather, the range of distance within which a diaphragm positioned to reflect light from the sending fiber to the receiving fiber may be adjusted within a very narrow range. The narrowness of the range is sufficiently precise to be effective for operational functionality of the pump.

The signal corresponding to the reflection of light quickly decays to a minimal value far from that corresponding to a trigger position. Whenever the diaphragm moves away from a specific location designed for the sensor. Thus, a detector in accordance with the invention provides a digital signal rather than an analog signal, for all practical purposes with respect to detecting the end of stroke for controlling the operation of the pump.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It will be readily understood that the components of the present invention, as generally described and illustrated in Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented inFIGS. 1 through 11, is not intended to limit the scope of the invention. The scope of the invention is as broad as claimed herein. The illustrations are merely representative of certain, presently preferred embodiments of the invention. Those embodiments will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout.

Referring toFIG. 1, an apparatus10for pumping a transfer fluid such as hot, de-ionized water, etching acids, or the like may be formed of components manufactured of exclusively of nonreactive, non-contaminating materials. In one embodiment, an apparatus10may be oriented to have a longitudinal direction11a, a lateral direction11b, a transverse direction11c, and a circumferential direction11d. The apparatus10comprises a pump12and a supporting apparatus14, such as a controller14or base14. In one embodiment, the controller14and base14may be integrated into a single component. As a practical matter, a controller14may be separate, distinct, remote, and external with respect to a pump12. Also, a base14may be manufactured to attach securely to a body16of a pump12. However, in one presently preferred embodiment, the pump12is integrated into a controller/base14all integrated into a monolithic unit. Thus, installation, control, integrity, valving, porting, fluid communications, and the like may be factory-integrated for an improved reliability. Moreover, contamination may be reduced, and the opportunities to damage or alter equipment upon installation are reduced. Moreover, the sealing technologies appropriate for operating with such nonreactive materials as fluoroplastics, creep-prone materials, may be implemented in the manufacturing assembly of the entire apparatus10as a pump12and controller/base14with accompanying interconnection.

The body16of the pump12may be referred to also as a frame. In one embodiment of an apparatus10in accordance with the invention, the body16replaces external frames, through-bolts, metallic connections, and the like. As a result, the apparatus10results in a very compact envelope having the features of reliable design, creep-insensitivity, durability, extremely long life, fail clean operation, and completely sealed fluid paths. The life of the apparatus10may exceed 10 million cycles. As a practical matter, units may be designed to exceed 20 million cycles, 30 million cycles, 40 million cycles, 50 million cycles, and 100 million cycles of the pump with no operational failure of any component. This is particularly important with respect to moveable components within the apparatus10.

The pump10may be configured to contain two chambers18. With reference toFIG. 2, the chambers18a,18b, are shown. The chambers18a,18bare simply specific instances of a generic chamber18. Hereinafter, trailing alphabetical references refer to specific instances of those items to which leading reference numerals refer.

Referring again to FIG.1and also referring generally toFIGS. 2-4, the pump12, may be manufactured to have slip rings20or union rings20. As a practical matter, alignment of the heads22with the frame16or body16is problematic in many designs of prior art pumps. Various notches, alignment marks, pins, and the like may be used to align the heads22with the frame16or body16. However, once aligned, each of the heads22may remain aligned with the body16, uninfluenced by the slip rings20as to alignment in a circumferential direction11d.

The slip rings20move circumferentially1dwith respect to the heads22. Accordingly, the heads22remain fixed with respect to the body16in a circumferential direction11d. By contrast, the slip rings20, in rotating in a circumferential direction11dmay thread onto the body16, drawing the heads22longitudinally11acloser in a sealing relationship with the body16. The slip rings20may thus be tightened to any particular loading, particular for heat soaking to relieve primary creep. In one embodiment, the slip rings20may be tightened to a design load tolerated by threads associated therewith, in order to seal the heads22against the body16. Thereafter, the pump12may be heat soaked in order to accelerate primary creep. Thereafter, the slip rings20may be tightened with no circumferential11ddisplacement of the heads22. Accordingly, tightening the slip rings20against the body16at a load and displacement effective to render the apparatus10subject only to secondary creep is easily trackable.

Ports24a,24bmay form an inlet24a, and outlet24b, respectively. Within the body16may be many suitable arrangements of check valves providing biasing of flows through the pump, preventing backflow. Double, serial check valves may provide a rectifier for the fluid flow from the inlet24a, through the chambers22, to the outlet24b.

In one embodiment, an aperture26may be formed in one end of the head22. A retainer28may be provided to thread or otherwise fasten to the aperture26, securing a pilot30or end-of-stroke detector30. The pilot30may be configured to detect the end of a stroke of the pump12for operation of a piston near the detector30or remote from the detector30. The pilot30may be used to signal the controller14in order to switch the direction of an operating fluid driving the pump12. According to the flows of operating fluids into the pump12, the transfer fluid being conducted through the inlet24aand outlet24bmay be appropriately driven and directed through the pump12.

In one embodiment, a retainer32may fit an aperture33in the base14. The retainer32may capture the components of the controller14within the base14. Accordingly, an aperture33may be adapted to extend an appropriate distance as needed in order to support the proper valving, porting, control mechanisms, and the like of the controller/base14.

In one presently preferred embodiment, mounts34connecting the base14to the pump12may actually integrate fittings. Thus, the mounts34or line fittings34may extend from the base14to the pump12for conducting fluids thereto. In one presently preferred embodiment, the mounts34are the basic lines34conducting operating fluid from the controller/base14into the heads22for driving the pump16. In one presently preferred embodiment, certain portions of the controller/base14may be disposed within a pedestal36. Moreover, the pedestal36may be adapted to fit against the frame16or body16of the pump12. Accordingly, the pedestal36may assist in the mounts34in supporting the pump12and restricting the motion thereof.

Referring again toFIG. 2, and continuing to refer generally toFIGS. 1-4, a latch block38may be provided for securing the controller/base14onto a support surface. The latch block38may be configured to engage the base14in any of a variety of methods for secure and convenient mounting.

A leak detector40may be provided in the heads22. In one embodiment, a leak detector40may also be used as an end-of-stroke detector30. The pilot30or end-of-stroke detector30ofFIG. 1, in one embodiment, may be a pneumatic and mechanical apparatus. In the embodiment of the detector40, an optical detection mechanism may be implemented to detect the end of a stroke of the pump12.

A pilot30, illustrated inFIG. 2as a short version for detecting an end of a stroke near the head22, as opposed to the detector30or pilot30ofFIG. 1, adapted to detect an end of stroke remote from the head and close to the body16, may be captured by a retainer42. Similarly, a leak detector40may be captured by a retainer44. The body46of the pilot30may thus be secured by sealing, wedging, threading, or the like into the head22. As a practical matter, certain pressurization of materials within the head, may form all sealing surfaces with respect to the body46. Accordingly, the retainer42may apply a force to the body46, forming a seal and maintaining loads on the seal. In another embodiment, the body46may be threaded directly into the head and forming a seal therewith.

A mount48for a leak detector40may be positioned within the head22. In one embodiment, the mount48may be threadedly engaged into the head22. By contrast, the actuator50of the pilot30is free to move longitudinally11awith respect to the pump12and head22.

The mount48of the leak detector40may be fabricated to include or support a window52. In one embodiment, the window52is adapted to be formed of a material identical to that of the head22. Accordingly, material compatibilities, creep, sealing, and the like may all be accommodated readily between the materials of the head22and mount48. Meanwhile, the mount48can be machined to formed a very thin window52adaptable to be translucent or transparent to light. Thus, a reflective beam from and returning to the leak detector40may pass through the window52into the chamber18, and back to the leak detector40for pickup or reception.

A cavity54or slot54may be provided within the leak detector40in order to accommodate passage of electronic or fiber optic lines. In one embodiment fiber optics are used up to the window52. Accordingly, the slot54may be used to adapt fiber optic lines to fit with their accompanying sheathings through the retainer44to the required proximity to the window52. A channel56may be provided through the retainer44in order to conduct such lines to a proper control center for interpretation and actuation with respect to any signal detected by the leak detector40. In one embodiment, profiles may be maintained in a minimum envelope by providing tool holes58adapted for rotating circumferentially11dthe retainers42,44. As a practical matter, substantial force may be developed by application of circumferential11dloads on metal prongs adapted to the tool holes58. Thus, less material, a cleaner profile, less chance of damage, and the like may be provided by use of the tool holes58to operate the retainers42,44.

Referring toFIGS. 3-4, and continuing to refer generally toFIGS. 1-2, as well, diaphragms60may be disposed within the chambers18of the pump12. The diaphragm60may be any isolation medium which is used to separate fluids such as drive fluids from working fluids. In one embodiment, a driver62, or plate62may be thought of as a piston62for communicating force or pressure between corresponding diaphragms60a,60b. An aperture63may be formed in driver62or piston62in order to accommodate a shaft64operably connecting the drivers62a,62b. The shaft64may travel through a barrel65formed in the body16of the pump12. The barrel65may be received, as illustrated, in order to minimize stress, and permit natural alignment of the drivers62, shafts64, and surfaces of the barrel65in the frame16.

A recess66may be provided in the body16as a cavity66for receiving each of the drivers62. In one embodiment, the recess66permits improved support of the diaphragms60in operation. More particularly, the recess66permits the minimization of any gaps between the body16and the driver62from leaving unsupported any substantial area of the diaphragm60. For example a contoured surface68formed in the head22may support the diaphragm60along its entire operational area. Similarly, a contoured surface70of the body16may be adapted to transition smoothly and snugly from the driver62. Accordingly, the diaphragm60bpositioned against the body16and the driver62bmay be completely supported even against the dead headed load, a stalled line, or a backflow in a line from which the pump has been shut down. Thus, whether position against the contoured surface68of the head22or against the contoured surfaces70of the body16and71of the drivers62, the diaphragm60is completely supported.

In one embodiment, as shown inFIG. 3, the driver62may be configured with a collection chamber67for fluid. The collection chamber67accumulates fluids as the driver62approaches against the body16. The driver62is further configured with a relief passage69for venting the collection chamber67, thus avoiding pressure buildup. Otherwise pressure buildup may distort components and reduce pump life.

An edge72or curvature72at an edge of a the body16may be smoothly transitioned to reduce or eliminate sources of stress concentrations in the diaphragms60in operation. For example, the curves72in the body16, and curves74in the heads22, provide for flexure of the diaphragm60in either longitudinal11awithout production of stress concentrations and without stretching or folding of the diaphragm60. In one presently preferred embodiment, all edges or corners of the body16, driver62, and head22of a pump12in accordance with the invention, are adapted to have curvatures72,74and clearances configured together to provide minimization of stress with virtual elimination of strain within the diaphragms60. Thus, unsupported spans are minimized by appropriate selection on clearance between components, such as between the driver62and body16with appropriate curvatures further reducing the probability of stress concentrations occurring.

In one presently preferred embodiment, a head22may be fabricated to have a cantilever76. A cantilever, may be thought of as a flange, but does not operate as a flange, as that term is typically used. No through holes are appropriate in one presently preferred embodiment of a cantilever76. Rather, the cantilever76merely forms a plate76or skirt76extending radially1b,11caway from the chamber18formed by the head22and body16. Cantilever76is preferably never in contact with the body16.

Referring toFIG. 3A, a driver78is shown which comprises a wedge80which is adaptable to fit into the cavity82of the body16for gripping and sealing the diaphragm60between the driver78and the body16. The driver78may be contiguous and integral with the wedge80. However, in another embodiment, the wedge80may be a separate ring having a trapezoidal cross-section. The trapezoid may be regular or irregular. In one presently preferred embodiment, the trapezoidal cross-section of the wedge80is exactly symmetrical in order to provide self-centering and equalization of loading. Thus, loading applied by the engagement portion84of the slip ring20a, which is transferred from the driver78of the head22to the wedge80, may be immediately transferred evenly by the wedge80to the diaphragm60and to the walls83of the cavity82in the body16.

In one presently preferred embodiment, the wedge80may be a separate, distinct, and freely movable piece, with respect to radial (the plane of the lateral1band transverse11cdirections) motions. Thus, no binding may occur to interfere with the wedge80evenly distributing forces into the cavity82of the body16. In one presently preferred embodiment, an engagement portion84of the slip ring20or the union nut20may threadedly engage the body16. Accordingly, the turning of the slip ring20may draw the head22, and particularly the cantilever76toward the body16longitudinally11a. The lip86of the slip ring20engages the cantilever76to drive the cantilever76in the longitudinal direction11a. Accordingly, the driver78, preferably integral to the cantilever76and head22drives the wedge80longitudinally11ainto the cavity82.

Continuing to refer to FIG.3A and generally toFIGS. 1-4, the wedge80may form a half angle87of approximately 15 degrees or a full angle88of approximately 30 degrees with respect to an axis89. An axis89may be an axis of symmetry89. However, in one embodiment, the wedge80is an irregular trapezoid having only one side tapered with a half-angle87. However, in one presently preferred embodiment, the wedge80has been found to be operationally superior with a symmetric form88.

Referring to FIG.3and generally toFIGS. 1-4, operation of the diaphragms60is controlled by a flow of operating fluid, such as air from the controller/base14into the chambers18toward the heads22. Accordingly, the chambers18pass a transfer fluid being pumped into and out of the chamber18between the diaphragms60and the body16. The flow of air in the controller14is effected by a shuttle valve90or spool valve90triggered by the pilot30.

Sealing the chamber18into two portions17,19is effected by the diaphragm60in conjunction with the wedge80. The portion17is formed by the diaphragm60in the head22. The portion19or chamber19, is formed by the body16and the diaphragm60. The volume of the respective chambers17,19or portions17,19of the chamber18fluctuate. Thus, each17,19, in turn, occupies the majority of the chamber18. The seal is effected by the force applied by the driver80of the head22against the wedge80, pinning or capturing the diaphragm60between the wedge80and the surface83of the cavity82.

The wedge80has been found so effective that a calendered fluoropolymer in a fluorocarbon body16and head22had been found to form a seal that is dramatically integral even after removal of any loading on the wedge80. Thus, a mechanical, but intimate bond, gas-tight is created between the wedge80, the diaphragm60, and the surface83of the cavity82in the body16. Due to the presence of the cantilever76, loading is maintained. Nevertheless, the sealing effect is superior, and requires no metallic, elastomeric, or other reactive components at any location in order maintain the loads and the seals effective to seal the pump12.

Referring toFIG. 5, and generally toFIGS. 1-6, a pilot30may be formed to have an element92adapted to be inserted in a head22under a retainer42. The element92may form a body92containing a piston94. The piston94may operate similarly to a spool. A shaft96may provide both alignment and sealing functions.

In one embodiment, a chamber98may be formed in the element92for containing a fluid. A vent100may be provided between the vented portion102or vented chamber102, that is contiguous with the chamber98, except for the presence of the piston94. Thus, the piston94and a bearing surface104or sealing surface104may form the vented chamber102.

The sealing for the fluid flows is provided by the piston94against the element92, and the shaft96against the sealing surface104. Relief106,108may be provided as appropriate. Thus, manufacturing tolerances may be provided, while binding is eliminated. For example, fastening may tend to warp and bind components.

In one embodiment, the shaft96may be provided with a bumper110adapted to make contact with a diaphragm60against a face71of a piston62. The bumper110may be adapted to fit a hollow portion112of the shaft96. A shank114may fit into an aperture116in the hollow portion112of the shaft96. Accordingly, the bumper110may be secured thereby to travel securely with the shaft96. Thus, the bumper110may provide stress distribution, abrasion resistance, and the like so as to minimize any deleterious affect by the shaft96on the diaphragm60. The shafts96may thereby follow the diaphragm60and piston62for detecting the end of the stroke of the piston62at the body16, rather than at the head22.

Threads118,119may be formed in the element92or body92of the pilot30ofFIG. 5. Ashoulder120may be adapted to stop the element92at an appropriate location in the head22. In one embodiment, a face122may abut a corresponding base in the head22. The wall124of the element92may be secured within a retainer42as illustrated inFIG. 1. Aface126may be driven or loaded by the retainer42thereagainst.

In operation, a passage128is formed between the element92and the head22. The passage128conducts fluid, as with a spool valve. Likewise, a passage130provides communication of the operating fluid (e.g. air) between the chamber102and a low-pressure area. Thus, the chamber98may be loaded with chamber pressure of the pump12, until the piston94passes a port100into the channel130. Thereupon, the pressure in the chamber98may be vented throughout the port100, indicating that the end of a stroke has been reached.

Referring toFIG. 6, and continuing to refer generally to refer toFIGS. 1-5, an element132of a short pilot30is illustrated. The pilot30may include an actuator50provided with a standoff134or post134extending into the chamber18associated with a head22. The posts136and actuator50are preferably made from a material, as all materials within the pump12and base/controller14that are nonreactive, chemically compatible with one another, and non-contaminating, in order to be fail-clean in the event of any failure of the apparatus10.

The post134may be provided with a face136adapted to contact a diaphragm60when the diaphragm60approaches or contacts the surface68of a head22. In one embodiment, the diaphragm60may push the face136of the post134flush with the surface68of the head22. Accordingly, the actuator50is freed to move the actual poppet140portion or valve portion140away from the seat142, exposing and opening the cavity144to pass operating fluid there through. The operating fluid (e.g. air) passes from the chamber18through the passage144between the poppet140and the seat142, to be discharged through the vents146in the sides of the actuator50.

A threaded portion148of a body46may secure an insert portion150within the head22. The face152may preferably be positioned near the contoured portion68of the head22. In one embodiment, the face152may be substantially flush therewith. In any event, the face136of the post134may protrude sufficiently to permit complete opening of the cavity144by movement of the post134by the diaphragm60and piston42.

In one embodiment, the body46may be provided with a shoulder154and relief156to assure clean and complete engagement by the head. The shoulder154may be straight or tapered with respect to the head. The shoulder154will maintain a virtually gas-tight seal with the head22.

Referring toFIG. 7, a leak detector40may be formed to have a channel54or cavity54adapted to receive fiber optic lines. In one embodiment, a clearance158may be provided between the head22and the mount48, assuring intimate access of the leak detector40to the window160. The thickness161of the window160may be selected to render the window160transparent or translucent with respect to the quantity, wave length, and intensity of light required by the leak detector40. The leak detector40is optical in nature. Accordingly, a face162may be formed at one end of the body164for fitting against the windows160. A clearance166may be provided on an opposite side of the window160.

In one embodiment, pin tool holes168may be provided. Remaining material supports against stresses and distortions in the mount48. Thus, the apparatus provides for assembly and dimensional stability in the window166.

A seal clearance170may be provided at the front of a passage172adapted to receive a fiber173. The fiber173may be glass or polymeric. In one presently preferred embodiment, the fiber173may be an acrylic plastic. Glass tends to be particularly brittle and not well adapted to handling. Thus, a clearance170may be provided for sealing the passage172with a nonreactive material. As a practical matter, the window160already provides a seal. Thus, the sealing clearance170is optional.

A face174or shoulder174is provided in one embodiment to restrict and position a sheath175surrounding a fiber173. In one embodiment, a fiber173is stripped of a sheath175for a distance sufficient to extend through the channel172. Accordingly, the passage176accommodates the entire sheath175, while the shoulder174positions the end of the sheath175, thereby permitting the fiber optic line173to extend toward the window160.

In one embodiment, a slot178may be formed in the leak detector40. The slot178is adapted to receive the sheath175and contained line173from both the channels172(only one is shown). The sheath175or leads175may then traverse from the slot178to be gathered into a channel54passing out of the leak detector40. The slot178has a primary effect of permitting the channels172to be positioned at a half angle184or full angle186of a center line188. Thus, the slot178provides adequate room for the turning required by the sheath175without damage to the fibers173or lines173of fiber optic material. Accordingly, the sheath175may then be routed throughout the channel54, exiting the leak detector40.

In one embodiment, a load180may be applied by a retainer44engaging the head22. The load180may be applied directly by the head182of the leak detector40. Thus, end of a contact may be maintained between the face162and the mount48and particularly the window160.

In operation one of the lines173may conduct a light beam to the window160. The light may be directed by the change in the index of refraction between the material in the line173, the window160, and air in the clearance166or the cavity17(chamber17of the chamber18). Thus, light directed from a line173is reflected back to the receiving fiber, in the presence of air. In the presence of a liquid, however, such as may occur during a leak caused by diaphragm or seal failure, the clearance166may become filled with a liquid. Accordingly, the index of refraction for light passing from the line173through the window160, and into the liquid160may be used to determine the angle186between the channels172and the lines173. The presence of liquid in the clearance166disburses the incoming light, thereby changing the index of refraction of the light reflected through clearance166, which is detected by the leak detector40. Thus, the leak detector40detects any change in the index of refraction which may be caused by a liquid or a gas leaking into the clearance166. In one embodiment, the window160may be positioned near to the diaphragm60. In such an embodiment, a reflection of light from the diaphragm proximate the window160may be detected by a line173receiving from a corresponding line173eliminating the diaphragm60.

The leak detector40may operate as an end-of-stroke detector30. However, the optical signals from the lines173must be converted into some kind of mechanical actuation to control the flow of air or other motive fluid or driving fluid into the chamber17for driving the diaphragm60.

Referring toFIG. 8, a spool valve90may be provided with a bias190or a bias element190for rendering a digital response from the spool valve90or shuttle valve90. In one embodiment, a bias force191is provided by the bias element190depending on the orientation thereof. The bias190is captured by a head192or nut192secured to a shaft193, capturing the bias192flexibly therebetween.

A chamber194adapted for ready movement by the bias190is provided by the retainer32and a fitting206. The chamber194permits free motion of the bias190in a longitudinal direction with respect to the shuttle valve90. A chamber196is formed for receiving the head192of the shuttle90. In one embodiment, a thickness198of a gap200formed to receive a bias190between the retainer32and fitting206may be critical. Forming a flange in place of the bias190provides residual stresses and restraints on deflection thereof.

Clearance is made to accommodate positioning of the bias190against a far corner202or a near corner204, with respect to the spool valve90or shuttle valve90. Thus, the bias190may be constrained in a radial direction199b, while being completely free in an axial direction199a, so long as the bias force191has been overcome. Thus, the bias190operates like the bottom of a traditional oil can.

Nevertheless, the constraint in a radial direction199bby the fitting206in no way restricts the positioning of the bias190in either corner202,204. Thus, the bias190is free to flip in an axial direction199aupon achievement of sufficient bias force191. Thus, the bias190renders the shuttle90a digital valve rather than a proportional valve. Proportional valving has been found to be unreliable, and not sufficiently precise for reliable operation of the pump12.

By contrast, the bias190by being formed of a stiff, comparatively rigid, yet flexible, nonreactive, fail-clean material, such as a chlorofluorocarbon formed in a comparatively strong, stiff sheet, has been found to be effective to provide a digital operation of the spool valve90within a narrowly designed range of bias floats191. The proper provision of a cap198that does not constrain the motion of the bias190and head192in an axial direction199ahas been found to be effective to provide such a digital positioning function.

Otherwise, the spool210of the spool valve90may otherwise operate as understood in the art. The seals212, generally, and specifically each of the seals213,214,216,218,219operate to direct fluid into a variety of conduits220or channels220. The channels220and specifically the channels221,222,224,226,228direct working fluid the operating fluid controlling the movement of the diaphragm in the head22of the pump12as heretofore described. Porting the working fluid (e.g. air) to the proper diaphragm60, or chamber17, in order to drive a diaphragm60, may be accommodated by the respective channel220, in response to a seal212directing the operating fluid from one port230to another230. Specifically, each of the ports231,232,234,236,238is opened, closed, and transferred between the respective channels240,242,244as a seal212is passed thereover or thereby longitudinally199a.

A driving fluid may be passed in through a channel240, and onto one of the channels220. A channel220connected to a port230may then transfer fluid into a channel242,244selected according to the longitudinal199aposition of the spool210. Thus, a particular seal212may direct communication of fluid from one port230to another230by way of one of the channels242,244extending circumferentially about the spool210.

In one embodiment, the spool210may be formed of a ceramic material. Accordingly, no elastomeric seals are formed anywhere in the apparatus10. Rather, each of the materials from which the spool210, head192, bias190, fitting206, retainer32, and base14are formed may be selected from nonreactive, durable non-contaminating, fail-clean materials such as chlorofluorocarbons.

Referring toFIGS. 9-11, a dump valve250or fast-relief, exhaust valve250may be formed to operate in the base14of an apparatus10in accordance with the invention. In one embodiment, an insert252may be adapted with a muffler254to fit into the base14. The muffler254may be provided with multiple ports256for dumping large amounts of operating fluid (e.g. air) from a non-recirculating, external driver or controller, after discharge thereof, from the chamber17of the pump12. The post258may serve to actuate and align operation of the valve253.

A disk260provides a principal seal260for the valve250. For example, operative fluid may be provided to or from the spool cavity262. Ports264and a support post266or cross266may be formed to pass operating fluid from the cavity262, while supporting the structural mechanics of the base14and the operation of the disk260. A channel268may similarly be disposed throughout the interior of the insert252. The channel268may communicate through a port270in the insert252.

The port270may form an aperture having a flat face275adapted to support the disk260therein. When the disk260is forced by a flow against the disk260to contact the flat face275the aperture270may be effectively closed by the disk260. The cross274supports the flat face275, providing ports270there through while supporting the disk260against failure in an axial direction199a.

A channel276conducts working fluid away from the disk260, by passing the fluid from the channel262, through the ports264drilled eccentrically with respect to the channel262, and accessing a cavity277on one side280aof the disk260. Clearances278provide passage for fluid around the perimeter281of the disk260. Accordingly, area in one direction may pass freely around the disk260, accessing the chamber276by way of the clearance278, which may be fluted to position the disks260effectively while still providing passage of fluid. Thus, fluid may pass through a suitable porting mechanism to the port282into a chamber284, for discharge throughout the ports256throughout the muffler254. By contrast, the disk260may also be biased to seal against the flat faced275, closing the ports270against passage of loads.