Embodiments of the present invention are directed to devices and methods for coupling, or joining components for containing, receiving and discharging fluids. Devices made in accordance with the present invention have special application to fittings, valves and check valves.
The present invention is directed to devices for containing, receiving and discharging fluids. Devices embodying features of the present invention include, by way of example, without limitation, tees, unions, fittings, valves and check valves. These devices are sometimes placed in line between two or more conduits that are joined in the form of a union, or tee, or valve. The term “union” is used in the sense of joining or bringing together. A “tee” is a form of fitting in which fluid flow is split or combined. The devices are sometimes part of a larger structure in which the device communicates through ports or openings of a housing of such structure.
In this application, the term “fitting” will be used in the broadest sense to refer to a device that may be placed in a larger structure, for example, a pump assembly, or in line.
The term “valve” is used in a conventional manner to denote a device that can stop fluid flow in a conduit or pipe. A check valve is a special valve that allows fluid to flow in one direction only.
Fitting and valves of the prior art typically have gaskets and seals that are separate and discrete parts. These gaskets and seals exhibit material creep, cold flow, relaxation and extrusion. That is, as the fluid pressure fluctuates, the gaskets move. This movement can lead to the gasket slipping from an original position, leading to gasket or seal failure.
This movement also creates a rebound of the gasket as the pressure is released, creating a potential pressure ripple. Analytical instruments, in particular, are sensitive to the rebound and pressure ripple effect.
These problems are amplified as the pressure contained by such devices increases. Analytical instruments, such as chromatography pumps and detectors typically operate at pressures of up to 5,000 pounds per square inch (psi) for High Pressure/Performance Liquid Chromatography (HPLC) and up to 20,000 psi for extreme pressure regimes. It is desirable to have analytical instruments operate at higher pressures, however, fittings, valves and check valves have a high failure rate at pressures greater than 3,000 psi.
Embodiments of the present invention are directed to devices and methods for containing, receiving and discharging fluids. One embodiment of the present invention directed to a device comprises a housing having a chamber for containing a fluid. The housing has a first gasket receiving surface for receiving a gasket. The device further comprises a gasket formed of a deformable material and having a first abutment surface and a second abutment surface. The first abutment surface is received on the first gasket receiving surface and the second abutment surface is for receiving a chamber closing piece. The device further comprises a chamber closing piece having a second gasket receiving surface. The chamber closing piece is for closing the chamber. At least one of the first gasket receiving surface of the housing and the second gasket receiving surface of the chamber closing piece has a retaining groove. The retaining groove having at least one edge to engage the gasket. The device further comprises compression means for compressing the gasket, deforming the material such that the gasket is pressed into the cavity and gripped by the edge of retaining groove to prevent gasket movement.
As used herein, the term “chamber” denotes the space in which fluids are held, received or discharged. For example, embodiments of the present invention are particularly suited for use in a check valve, in which case the housing is a check valve housing. The chamber may comprise any of the interior spaces in which fluid is held. Preferably, the chamber is the chamber in which the flow closing element is held, such as a ball of flap or rotary structure.
The chamber closing piece may comprise any part, component or assembly which mates to the gasket and the housing.
Preferably, at least one of the first gasket receiving surface and the second gasket receiving surface define a plane. And, the retaining groove has a recessed wall having an angle with respect to the plane of the first gasket receiving surface and the second gasket receiving surface in which it is placed. A preferred angle is in a range of 45 to 135 degrees from the plane. The retaining groove can define a “V” in the surface in which it is placed.
Preferably, the gasket receiving surface has a machined surface with a circular lay. The circular lay cooperates with the gasket and compression means to hold the gasket against movement.
Preferably the gasket is comprised of a material having a friction coefficient of at least 0.2. A preferred deformable material is a polyaryl ketone or ethelene. A preferred polyaryl ketone or ethelene is selected from the group of compositions consisting of polyetheretherketone (PEEK), polytrifluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), perfluoroalkoxy (PFA), and fluoronated ethylenepropylene (FEP) and mixtures thereof. Preferably, the material is at least eighty percent polyetheretherketone (PEEK).
A preferred, gasket has a thickness between 0.001 and 0.005 inches. This thin gasket exhibits a small area to the chamber and fluids contained therein to limit the area that will have greater elasticity. The thickness of the gasket influences the depth of the retaining groove. Preferably, the retaining groove has a depth, and the thickness of the gasket is equal to or exceeds the depth.
Preferably, the first gasket receiving surface or second gasket receiving surface in which the cavity is placed has a first edge proximal to the chamber and a second edge distal to the chamber. The distance between the first edge and the second edge has a midpoint, and the retaining groove is at approximately the midpoint or towards the first edge to minimize pressure ripple.
A further embodiment of the device comprises a first housing having an first passage and first mounting gasket receiving surface. The first passage is for receiving or discharging fluid to a second passage in a second housing. The first mounting gasket receiving surface is for compressing a gasket against the second housing to place the first passage in fluid communication with a second opening of the second housing. The first mounting gasket receiving surface is recessed in a gasket cavity for receiving a deformable gasket. The device further comprises a second housing having a second mounting gasket receiving surface and a second passage. The second passage is for receiving or discharging fluid to the first passage in the first housing. The second monthly gasket receiving surface is for compressing a gasket against the first mounting gasket receiving surface of the first housing to place the second passage in fluid communication with the first passage. The device further comprises a gasket having a thickness and constructed and arranged to be received in the gasket cavity with at least five to twenty five percent of the thickness of the gasket protruding from the cavity in an unloaded position. And, the device comprises compression means to press the first housing and second housing together to compress said gasket to make a fluid connection between said first opening and said second opening.
Upon compression by compression means, the gasket has, approaching none to five percent and most preferably one percent or less, of the height protruding. The mass of the gasket is directed, preferably, into a deformed gasket receiving area of the gasket cavity. The deformed gasket receiving area of the gasket cavity does not contain gasket in the unloaded position, that is, non-compressed state. Thus, the gasket is not directed out between the coupling surfaces but into the cavity. The deformed material of the gasket is more elastic and more likely to contribute to pressure ripple.
A preferred cavity has a trapezoid shape. The trapezoid has acute angles at the base to form the gasket receiving area. The gasket is held by the edges of the cavity.
The gasket has a height under compression and a height without compression. Preferably, the height under compression 15 to 30% of the height without compression. The gasket has a total surface area, an unloaded surface area exposed to non gasket receiving surfaces and a loaded surface area exposed to non-gasket receiving surfaces. The loaded surface have a range approaching zero to 5% of the total surface area and an unloaded surface area have a range of approximately 6 to 11% of the total surface area of the gasket.
Preferably, the material is a polyaryl ketone or ethelene. Preferred polyaryl ketones and ethelenes are selected from the group of compositions consisting of polyetheretherketone (PEEK),polytrifluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), perfluoroalkoxy (PFA), and fluoronated ethylenepropylene (FEP) and mixtures thereof.
Embodiments of the present invention are ideally suited for applications wherein the first housing is a valve housing, and, in particular, a check valve. These valves are placed in pumps wherein the second housing is a pump housing.
In such applications, compression means comprises a screw fitting and cooperating thread on a pump housing. The first housing is coupled to the screw fitting and the second housing has cooperating threads to receive the screw fitting. The screw fitting is rotated with respect to the second housing, which upon tightening, compresses the gasket.
Device of the present invention are capable of containing and conveying fluid under pressure greater than 5,000 psi.
Further embodiments of the present invention are directed to a method of making the device and using the device as described.
These and other features and advantages will be apparent to those skilled in the art upon viewing the drawings and reading the detailed description that follows.
Embodiments of the present invention will now be described with respect to the Figures, with the understanding that the Figures and the description are directed to the preferred embodiments of the present. Embodiments of the present invention have particular utility as valves and connectors. However, embodiments of the present invention have application with respect to any fluid conveying or containing device operating under pressure.
Referring now to
The device 21 is in the nature of a valve and has a check valve assembly comprising a ball 41 and spring 43. Those skilled in the art will recognize that other valve assemblies may be substituted for the ball 41 and the spring 43. For example, the valve assembly may comprise a stator and rotor of a rotating valve, plunger and seat assembly or swinging flap [not shown]. The ball 41 and the spring 43 are constructed and arranged in chamber 27 to operate in a conventional manner. That is, the ball 41 and spring 43 allow the flow of fluid in a single direction.
Housing 25 has a first interior wall 45a, cylindrical in form, that defines chamber 27. As best seen in
The closing piece 37 is cylindrical in shape to cooperate and fit within the second interior wall 45b. As best seen in
Compression means 33 may take several forms. As illustrated, compression means 33 comprises a screw fitting 55 having a fitting first wall 57. Preferably, fitting first wall 57 and housing third wall 45c have cooperating threads such that relative rotation of the screw fitting 55 and housing 25 moves the screw fitting within the cavity of the housing third wall 45c.
Screw fitting 55 has a compression post 59, cylindrical in formed and constructed and arranged to cooperate and fit within the second interior wall 45b of the housing 25. The compression post 59 has a post gasket receiving surface 61 for receiving second gasket 31b. Screw fitting 55 has an axial fitting opening 63 allowing fluid communication with the chamber 27 upon opening of the check valve assembly 35. Fitting opening 63 has an expanded section 65 for receiving a fluid coupling [not shown] comprising tubing or conduits and appropriate connecting fitting known in the art.
First and second gaskets 31a and 31b are formed of a deformable material such as soft metals or plastic. A preferred material is a polyaryl ketone or ethylene. One particularly preferred material is comprised of at least 80% polyetheretherketone (PEEK). Preferably, gaskets 31a and 31b are comprised of a material having a friction coefficient of at least 0.2.
Preferably, turning now to
First and second gaskets 31a and 31b have a gasket stress factor of two to four times the anticipated fluid pressure to which the gaskets will be subjected. The term “gasket stress factor” is used to denote the multiplying factor between the contact stress pressure (i.e., the compression on the components of the fitting) versus the fluid pressure of the liquid flowing in the fitting. This relationship can be described in the following formula:
Contact stress pressure =fluid pressure X gasket stress factor.
The contact stress pressure is preferably greater than the anticipated fluid pressure. The present invention has particular utility for conveying or containing fluids at pressures up to approximately 15,000 psi.
The thickness of the gaskets 31a and 31b is selected to cooperate with gasket retaining recesses carried on one or more gasket receiving surfaces selected from housing gasket receiving surface 49, closing piece gasket receiving surfaces 51a and 51b and post gasket receiving surface 61. Preferably, at least one of opposing gasket retaining surface, such as housing gasket retaining surface 49 and closing piece gasket receiving surface 51a, on one hand, and closing piece gasket receiving surface 51b and post gasket receiving surface 61, on the other, has a retaining groove. As best seen in
Turning now to
The retaining groove 67b has a depth 71 measured from the top of the post gasket receiving surface 61. Preferably, the thickness of the gasket 31a received on the post gasket receiving surface 61 is equal to or greater than the depth 71 of the retaining groove 67b.
The retaining groove 67b in
The edges 73a and 73b have an angle measured from the plane of the post gasket receiving surface 61 to the descending walls 75a and 75b. Preferably, the angle is 35 to 135 degrees. The edges 73a and 73b are pressed into the gasket 31a and prevent movement and creep of the gasket 31a during pressure cycles.
As best seen in
The gasket receiving surfaces comprising housing gasket receiving surface 49, closing piece gasket receiving surfaces 51a and 51b and post gasket receiving surface 61 have a circular lay. Those skilled in the art of machining will understand that a circular lay refers to machining with a circular motion around the center of the piece. The circular lay produces small grooves [not shown] which further grip the gasket 31a or 31b.
Turning now to
Device 21 has a passage 29 in communication with chamber 27 and extending through the first mounting gasket surface 87. Passage 29 is in fluid communication with a pump passage 91 to receive fluid under pressure and allow such fluid to enter chamber 27.
Device 21 has an end wall 93 having a planar surface and recess walls 95a and 95b which cooperate to partially contain mounting gasket 85 on mounting gasket surface 87. Gasket 85 is deformable. Under conditions of no compression, mounting gasket 85 will have an at rest inner and outer radius and under conditions of compression, the mounting gasket will have a load inner and outer radius. Similarly, under condition of compression, the mounting gasket will exhibit an at rest thickness and under load it will exhibit a load thickness. Preferably, the mounting gasket has a thickness such that under compression, 5 to 25% of the gasket mass is forced out beyond the recess wall 95 inner and outer at rest radius. Under compression, the thickness under compression is 15 to 30 percent of the thickness without compression. The mounting gasket 85 has a loaded surface area and an unloaded surface area. The loaded surface area has a range approaching zero to 5 percent of the total surface area and unloaded surface area of 6 to 11 percent of the total surface area.
Turning now to
The mounting gasket 85 is made of a polymeric plastic material such as, polyaryl ketone or ethelene. Preferred polyaryl ketones and ethylenes are selected from the group consisting of polyetheretherketone (PEEK), polytrifluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), and perfluoroalkoxy (PFA) and fluoronated ethylenepropylene (FEP) and mixtures thereof. The non-gasket components are made of metal. A preferred metal is stainless steel.
Turning now to
The operation of the device 21 is exemplified in the method of making and using device 21. Turning now to
Turning now to
The device 21 may withstand pressures of up to 15,000 psi. Thus, the devices and methods of the present invention are ideally suited for high pressure applications. Devices made in accordance with the present invention do not exhibit material creep, cold flow relaxation and extrusion. That is, as the fluid pressure fluctuates, the gaskets do not move significantly from the original position. Thus, embodiments of the present invention provide devices which exhibit resistance to gasket failure.
These features and advantages have been described with respect to the drawings and detailed description which describe preferred embodiments of the present invention. Those skilled in the art will recognize that the present invention can be altered and modified with out departing from the teaching herein. And, the present should not be limited to the precise details but should encompass the subject matter of the following claims and equivalents thereto.
This application claims priority from U.S. Provisional Patent Application Ser. No. 60/604,145, filed Aug. 24, 2004. The contents of these applications are incorporated herein by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US05/30199 | 8/24/2005 | WO | 00 | 10/10/2007 |
Number | Date | Country | |
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60604145 | Aug 2004 | US |