DEVICE FOR CONTROLLING THE FLOW OF FLUID

Abstract

Device (11) for controlling the flow of fluid, comprising: a. a rotor (13) comprising a rotor fluid communication means and at least one rotor load bearing surface (23), wherein the rotor load bearing surface (23) engages a stationary load bearing surface (25) in a sealing manner, wherein the rotor (13) is capable of assuming a first position and a second position by rotation; b. at least one stator (15) having the stationary load bearing surface (25) having the stator fluid communication means, wherein the stationary load bearing surface (25) engages the rotor load bearing surface (23) in a sealing manner and enables the rotation of the rotor (13) with respect to the stator (15), wherein in the first position the rotor fluid communication means and the stator communication means prevent the flow of fluid, and in the second position the rotor fluid communication means and the stator communication means enable the flow of fluid, wherein at least the rotor load bearing surface (23) and / or the stationary load bearing surface (25) has a diamond-like carbon silica coating; c. Compression means (17) for holding the at least one stator (15) and the rotor (13), wherein the rotor load bearing surface (23) and the stationary load bearing surface (25) are in sealing engagement.

Description

AREA OF INVENTION

[0001] The invention relates to valves, and in particular high-pressure valves, used in instruments for chemical analysis, in which such valves are subjected to repeated opening and closing cycles and aggressive solvents. BACKGROUND OF THE INVENTION

[0002] The invention relates to actuated valves with moving parts, or valves with moving parts under load. These parts often need to maintain fluid integrity; that is, such parts should not exhibit fluid leakage. However, if the valve is cyclically moved or switched between an open and a closed position, the load or actuation acting on the moving parts leads to wear. The load on moving parts, typically a stator and a rotor, of a valve used in analytical instruments can be significant. Analytical instruments, such as high-performance chromatography pumps (HPLC pumps), are typically operated at pressures up to 3000 pounds per square inch (psi). There is considerable interest in operating at even higher pressures.The term "ultra" is used here to refer to pressures above approximately 4000 psi. However, there are numerous fluidic components that operate at low pressures of 100 psi to a few hundred psi and have a high number of cycles.

[0003] As the system pressure increases, the wear on the valve's moving parts increases, and the valve's service life, measured in cycles, decreases. A conventional valve only has a service life of 150,000 cycles at these ultra-high pressures.

[0004] It would be desirable to have valves suitable for operation at higher pressures and with a service life exceeding 150,000 cycles. US 2003 / 0116206A1 discloses a microfluidic valve and a method for its manufacture. DE 69503246T2 discloses a sterilizable rotary valve or a linear sliding valve that can be used in conjunction with liquid chromatography columns and sterilizing fluid handling systems to separate and / or purify biological macromolecules important for the pharmaceutical industry. US 6,453,946B2 discloses a long-life fluid switching valve. SUMMARY OF THE INVENTION

[0005] The invention is defined in the claims. A method and a device for controlling the flow of fluid are disclosed therein. One embodiment of the device for controlling the flow of fluid comprises a rotor, a stator, and a compression means. The rotor has a rotor fluid communication means and at least one rotor load bearing surface. The rotor load bearing surface engages a stationary load bearing surface in a sealing manner. The rotor is capable of assuming a first position and a second position by means of rotation. The stator has a stationary load bearing surface which includes a stator fluid communication means. The stationary load bearing surface engages the rotor load bearing surface in a sealing manner and enables rotation of the rotor relative to the stator.The rotation of the rotor provides a first position in which the rotor fluid communication medium and the stator fluid communication medium prevent fluid flow, and a second position in which the rotor fluid communication medium and the stator fluid communication medium allow fluid flow. At least the rotor bearing surface and / or the stationary load bearing surface (stator load bearing surface) has a diamond-like carbon-silica coating. A compression element holds the stator and the rotor. The stator and rotor are held in place by the sealing engagement of the rotor load bearing surface and the stationary load bearing surface. The diamond-like carbon-silica coating exhibits low friction and increased hardness, enabling repeated movement between the first and second positions.

[0006] In fact, embodiments according to the present invention are suitable for more than 900,000 cycles. This number of cycles exceeds the number of cycles previously achieved with valves without a diamond-like carbon-silica coating by a factor of six. These results are surprising and unexpected.

[0007] Preferably, the compression means is a housing. A conventional valve housing has a chamber for receiving the rotor and a means for holding at least one stator. Means for holding the stator are known and can include clamps, screws, and interacting threads on the stator and the housing.

[0008] The stator fluid communication means can comprise at least one stator opening in the stator. The stator opening is arranged in fluid communication with a line. Preferably, the stator has two stator openings, one in communication with an inlet line and the other in communication with an outlet line. Alternatively, the housing can have an opening for arranging fluid in communication with a line and the rotor fluid communication means. The rotor fluid communication means comprises at least one opening and one or more channels for arranging two or more stator openings in fluid communication.

[0009] Preferably, the diamond-like carbon-silica coating consists of 40-90% carbon, 20-40% hydrogen, and 0.01-5% silica carbon, and more preferably of 50-80% carbon, 25-35% hydrogen, and 0.1-5% silica carbon. A preferred diamond-like carbon-silica coating is the DLC coating marketed by Morgan Advanced Ceramics, Inc. (Allentown, Pennsylvania, USA).

[0010] Preferably, at least the rotor and / or the stator consists of a material selected from polyetheretherketone, tetrafluoroethylene, combinations of polyetheretherketone and tetrafluoroethylene, stainless steel, titanium, and aluminum. Preferred combinations of polyetheretherketone and tetrafluoroethylene contain 50–90% polyetheretherketone and 10–50% tetrafluoroethylene. More preferably, the combinations contain 60–80% polyetheretherketone and 20–40% tetrafluoroethylene.

[0011] Preferably, at least the rotor and / or the stator are made of stainless steel, titanium, and aluminum, and at least the rotor and / or the stator are made of polyetheretherketone and tetrafluoroethylene, and combinations of polyetheretherketone and tetrafluoroethylene. The rotor and the stator made of stainless steel, titanium, and aluminum preferably have a diamond-like carbon-silica coating.

[0012] Also disclosed is a method for controlling the flow of fluid. The method comprises the steps of providing a device having a rotor, at least one stator, and a compression means. The rotor has a rotor fluid communication means and at least one rotor load bearing surface, wherein the rotor load bearing surface engages a stationary load bearing surface in a sealing manner. The rotor is capable of assuming a first position and a second position by rotation. The stator has a stationary load bearing surface which includes a stator fluid communication means. The stationary load bearing surface engages the rotor load bearing surface in a sealing manner and enables rotation of the rotor with respect to the stator. When the rotor is in the first position, the rotor fluid communication means and the stator fluid communication means prevent the flow of fluid.When the rotor is in the second position, the rotor fluid communication medium and the stator fluid communication medium allow fluid flow. At least the rotor bearing surface and / or the stationary load bearing surface has / have a diamond-like carbon-silica coating. The compression medium holds the stator and rotor, with the rotor load bearing surface and the stationary load bearing surface in sealing engagement. The diamond-like carbon-silica coating imparts low friction and increased hardness to the surface to which it is applied, enabling repeated movement between the first and second positions. The method further includes the step of rotating the rotor from the first or second position to the other position to control the fluid flow.

[0013] Embodiments of the present method and apparatus allow a device for controlling the flow of fluid, i.e., a valve, to be moved back and forth 300,000 to 900,000 times or more. These and other features and advantages will become apparent to the person skilled in the art upon reading the detailed description below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows an exploded view of a device embodying features according to the present invention. Fig. Figure 2 shows a rotor embodying features according to the present invention. Fig. Figure 3 shows a stator embodying features according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Embodiments of the present invention are described in detail with regard to a device for controlling the flow of fluid. However, those skilled in the art will recognize that features of the present invention can also be applied in other devices. Embodiments of the present invention are applicable to moving parts in any device in which a fluid must be held under pressure in a container.

[0015] In Fig. Figure 1 is a device for controlling the flow of fluid, generally designated by reference numeral 11, shown in exploded view. The device 11 comprises a rotor 13, a stator 15, and a compression means 17.

[0016] How best to do this Fig. As can be seen from Figure 2, the rotor 13 has a rotor fluid communication means in the form of a channel 21 and at least one rotor load bearing surface 23. The rotor load bearing surface 23 engages a stationary load bearing surface 25 in a sealing manner, which is described below with respect to the stator 15. The rotor 13 is capable of assuming a first position and a second position by rotation with respect to the stator 15. The rotor 13 has a circular wall 27, which serves as a bearing surface. The rotor has an elliptical groove 29. The elliptical groove 29 cooperates with the signal pin 31. The signal pin 31 has a finger 33 that moves in the elliptical groove 29. The signal pin 31 is either extended away from the stator 15 or retracted towards the stator 15, depending on the position of the rotor 13.

[0017] How this manifests itself Fig. 1 and Fig.As can be seen from Figure 3, the stator 15 has a stationary load bearing surface 25 which includes a stator fluid communication means in the form of two openings 39a and 39b. The stationary load bearing surface 25 engages the rotor load bearing surface 23 in a sealing manner and enables the rotation of the rotor 13 relative to the stator 15.

[0018] The stator 15 has a pin channel 41a to hold the signal pin 31 and engage it in a sliding manner. A bearing channel 41b surrounds the stationary load bearing surface 25 to facilitate the alignment of the rotor 13.

[0019] Rotation of the rotor 13 provides a first position in which the rotor fluid communication means and the stator fluid communication means prevent fluid flow. Rotation of the rotor provides a second position in which the rotor fluid communication means and the stator fluid communication means allow fluid flow. In other words, in one position, the channel 21 is in fluid communication with the openings 39a and 39b of the stator 15, and in another position, the channel is not aligned with one or more of the openings 39a and 39b. It is obvious that the person skilled in the art will recognize that the valves can then have two positions. The terms "first position" and "second position" are used to encompass any number greater than 1.

[0020] Alternatively, the rotor 13 can have one or more openings (not shown) that interact with one or more openings in the stator 15, such as openings 39a and 39b. In this embodiment, a second stator (not shown) is used to interact with the openings in the rotor. This second stator has further openings of the type of stator 15 or one or more channels in the face of the rotor 13.

[0021] The stator 15 and the rotor 13 are held such that the rotor load bearing surface 23 and the stationary load bearing surface 25 are in sealing engagement. At least the rotor load bearing surface 23 and / or the stationary load bearing surface 25 has / have a diamond-like carbon silica coating. The diamond-like carbon silica coating provides low friction and increased hardness, which enables repeated movement between the first and second positions.

[0022] Preferably, the diamond-like carbon-silica coating consists of 40-90% carbon, 20-40% hydrogen and 0.01-5% silica carbon, and more preferably of 50-80% carbon, 25-35% hydrogen and 0.1-5% silica carbon.

[0023] A preferred diamond-like carbon silica coating is a DLC coating distributed by Morgan Advanced Ceramics, Inc. (Allentown, Pennsylvania, USA). Diamond-like carbon silica coatings and methods for applying such coatings to a surface, such as the stationary load bearing surface 25 and the rotor load bearing surface 23, are described in the following US patents: US 4,382,100 A, US 5,135,808 A, US 5,190,807 A, US 5,268,217 A, US 5,506,038 A, US 5,508,092 A, US 5,508,368 A, US 5,527,596 A, US 5,618,619 A, US 5,635,245 A, US 5,643,423 A, US 5,653,812 A, US 5,679,413 A, and US 5,844,225 A.

[0024] Preferably, at least the rotor 13 and / or the stator 15 consists of a material selected from polyetheretherketone, tetrafluoroethylene, combinations of polyetheretherketone and tetrafluoroethylene, stainless steel, titanium, and aluminum. Preferred combinations of polyetheretherketone and tetrafluoroethylene comprise 50–90% polyetheretherketone and 10–50% tetrafluoroethylene. More preferably, the combinations comprise 60–80% polyetheretherketone and 20–40% tetrafluoroethylene.

[0025] Preferably, at least the rotor 13 and / or the stator 15 are made of stainless steel, titanium, and aluminum, and at least the rotor 13 and / or the stator 15 are made of polyetheretherketone and tetrafluoroethylene, and combinations of polyetheretherketone and tetrafluoroethylene. The rotor 13 and the stator 15, which are made of stainless steel, titanium, and aluminum, preferably have a diamond-like carbon-silica coating. As shown, the rotor 13 is made of stainless steel, and the rotor bearing surface 23 has a diamond-like carbon-silica coating.

[0026] To facilitate the rotation of the rotor 13 into the first position and / or the second position, the rotor 13 is connected to a shaft 55 or to it via a linkage. The rotation of the shaft 55 results in a corresponding rotation of the rotor 13. In a typical application of the device 11, the shaft 55 is coupled to a motor (not shown).

[0027] The compression means 17 for holding the stator 15 and the rotor 13 comprises a housing 61a and 61b, the rotor bearing 63, the rotor wheel 65, the spring 67 and the bearing arrangement 69.

[0028] The housing 61a and 61b comprises a lower housing unit 61a and an upper housing unit 61b. The lower housing unit 61a accommodates the stator 15 and is secured by suitable means, such as screws 71 or pins (not shown), clamps (not shown), or other suitable retaining devices. The lower housing unit 61a and the stator 15 can be formed as a single-piece structure. The lower housing unit 61a has projections 73a and 73b extending from a flat, planar surface 75. The projections 73a and 73b provide space for accommodating other parts of the compression element 17.

[0029] The lower housing unit 61a has a bearing opening 77 to accommodate the rotor bearing 63. The rotor bearing 63 has a rotor opening 79. The rotor 13 is held in the rotor opening 79 within the rotor bearing 63, and the rotor bearing 63 is held in the bearing opening 77, allowing the rotor 13 to rotate within the lower housing 61a. The rotor 13 and the rotor bearing 63 are nested in the bearing channel 41 of the stator 15 to facilitate positioning of the rotor 13.

[0030] The rotor wheel 65 is wedged to the rotor 13 and is visible in the assembled state and suitable for manual manipulation, protruding through a space between the projections 73a and 73b of the lower housing unit 61a. The rotor wheel 65 provides means for manually rotating the rotor 13 and provides means for attaching optical markers (not shown) which are read by optical sensors (not shown) in communication with computer means (not shown).

[0031] The spring 67 pre-tensions the rotor 13, the rotor wheel 65, against the stator 15. The spring 67 is arranged around the shaft 55 and is compressed by the bearing arrangement 69 during assembly. The shaft retaining clip 81 holds the shaft 55 within the upper housing unit 61b. The upper housing unit 61b is fastened to the lower housing unit 61a by means of screws 83 or pins, clamps, or other suitable means.

[0032] Also disclosed is a method for controlling the flow of fluid. This method is described with regard to the operation of the device 11. The method comprises the steps of providing a device having a rotor 13, at least one stator 15, and a compression means 17. The rotor 13 has a channel 21 and at least one rotor load bearing surface 23, wherein the rotor load bearing surface engages a stationary load bearing surface 25 in a sealing manner. The rotor 13 is capable of assuming a first position and a second position by rotation. The stator 15 has a stationary load bearing surface 25, which has openings 39a and 39b. The stationary load bearing surface 25 engages the rotor load bearing surface 23 in a sealing manner. The rotor 13 has at least two openings by rotation.When the rotor is in the first position, channel 21 and openings 39a and 39b are misaligned and prevent fluid flow. When the rotor is in the second position, channel 21 and openings 39a and 39b are aligned and allow fluid flow.

[0033] At least the rotor bearing surface 23 and / or the stationary load bearing surface 25 has / have a diamond-like carbon-silica coating. The compressive force holds the stator 15 and the rotor 13 such that the rotor load bearing surface 23 and the stationary load bearing surface 25 are in sealing engagement. The diamond-like carbon-silica coating imparts low friction and increased hardness to the surface to which it is applied, thus enabling repeated movement between the first and second positions. The method further includes the step of rotating the rotor 13 from the first position or the second position to the other position to control the fluid flow.

[0034] Embodiments of the present method and apparatus allow a device for controlling the flow of fluid, i.e., a valve, to be moved back and forth 300,000 to 900,000 times or more. In fact, embodiments according to the present invention are suitable for more than 900,000 cycles. The number of cycles exceeds the number of cycles previously achieved with valves without a diamond-like carbon-silica coating by a factor of 6. These results are surprising and unexpected.

[0035] The foregoing descriptions of embodiments of the present invention are understood to represent a preferred embodiment and the best way of manufacturing and using the present invention. Those skilled in the art will recognize that the features described herein can be further modified and altered.

Claims

[1] Device (11) for controlling the flow of fluid, comprising: a. a rotor (13) comprising a rotor fluid communication means and at least one rotor load bearing surface (23), wherein the rotor load bearing surface (23) engages a stationary load bearing surface (25) in a sealing manner, wherein the rotor (13) is capable of assuming a first position and a second position by rotation; b. at least one stator (15) having the stationary load bearing surface (25) having the stator fluid communication means, wherein the stationary load bearing surface (25) engages the rotor load bearing surface (23) in a sealing manner and enables the rotation of the rotor (13) with respect to the stator (15), wherein in the first position the rotor fluid communication means and the stator communication means prevent the flow of fluid, and in the second position the rotor fluid communication means and the stator communication means enable the flow of fluid, wherein at least the rotor load bearing surface (23) and / or the stationary load bearing surface (25) has a diamond-like carbon silica coating; c. Compression means (17) for holding the at least one stator (15) and the rotor (13), wherein the rotor load bearing surface (23) and the stationary load bearing surface (25) are in sealing engagement. [2] Device (11) according to claim 1, wherein the compression means (17) is a housing (61a, 61b), the housing (61a, 61b) having a chamber for receiving the rotor (13) and a means for holding the at least one stator (15). [3] Device (11) according to claim 1, wherein the stator fluid communication means is at least one stator opening in the stator (15), wherein the at least one stator opening is configured to be arranged in fluid communication with a line. [4] Device (11) according to claim 1, wherein the rotor fluid communication means comprises at least one opening. [5] Device (11) according to claim 3, wherein the rotor fluid communication means comprises a channel (21) to arrange two or more stator openings in fluid communication. [6] Device (11) according to claim 1, wherein the diamond-like carbon silica coating consists of carbon, 20-40% hydrogen and 0.1-5% silica carbon. [7] Device (11) according to claim 1, wherein at least the rotor (13) and / or the stator (15) consists of a material selected from polyetheretherketone, tetrafluoroethlene, combinations of polyetheretherketone and tetrafluoroethlene, stainless steel, titanium and aluminium. [8] Device (11) according to claim 7, wherein the combination of polyetheretherketone and tetrafluoroethlene comprises 50-90% polyetheretherketone and 10-50% tetrafluoroethlene. [9] Device (11) according to claim 7, wherein the combination of polyetheretherketone and tetrafluoroethlene comprises 60-80% polyetheretherketone and 20-40% tetrafluoroethlene.

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