Gradient proportional valve

Abstract

The present invention discloses a gradient proportional valve for liquid chromatography, the gradient proportional valve comprising a plurality of inlet ports, the plurality of inlet ports being configured to receive a plurality of fluids; a manifold, the manifold being connected to each of the plurality of inlet ports, the inlet ports being configured to mix the plurality of fluids in a controlled manner to provide a liquid composition, the manifold comprising a plurality of conduits inside the manifold, each of the plurality of conduits receiving a fluid through a corresponding inlet port of the plurality of inlet ports; an actuating mechanism, the actuating mechanism having a piston, the piston being located within a drilling structure surrounding the piston, the actuating mechanism being configured to open and close at least one of the plurality of conduits in a controlled manner, wherein the piston and the drilling structure have a tight tolerance configured to produce a fluid-tight seal; and a common outlet port, the common outlet port being configured to receive the fluid composition.

Description

[0001] Related Applications

[0002] This application is a non-provisional patent application claiming priority to U.S. Provisional Patent Application No. 62 / 941,236, entitled “Gradient Proportioning Valve,” filed on November 27, 2019, which is incorporated herein by reference. Technical Field

[0003] The present invention generally relates to gradient proportional valves. More particularly, the present invention relates to gradient proportional valves having damping features and associated systems and methods. Background Art

[0004] In liquid chromatography, solvent managers are used to deliver mobile phase solvents to the rest of the instrument stack at very precise flow rates, pressures, and solvent compositions. In one example, a quaternary solvent manager (QSM) is a solvent manager that measures and mixes solvents at low pressure before pressurizing and delivering the solvents to the rest of the instrument stack. Metering of solvents at low pressure is typically performed by a gradient proportioning valve (GPV).

[0005] GPVs are known for use in low pressure mixed liquid chromatography systems (i.e., quaternary systems). U.S. Patent No. 5,862,832 describes an exemplary prior art GPV. Specifically, the GPV is responsible for setting the desired solvent composition in the system. A typical GPV includes multiple solenoid valves mounted on a common manifold that open and close at precise times relative to the system pump cycle. When the GPV solenoid valves are opened and closed, pressure pulses are introduced into the system. Pressure pulses are also caused by the start and end of the intake stroke during the pump cycle. Such pressure pulses can cause unwanted oscillations in the composition error of the chromatography system. Therefore, these oscillations reduce the composition accuracy and performance of the liquid chromatography system.

[0006] Typical GPVs use a flexible diaphragm or poppet valve to form a seal when switching the inlet channel open and closed. At each actuation, an unwanted pressure pulse is generated by the valve and introduced into the solvent. These pressure pulses cause errors in the metering of solvents using the GPV, and therefore may affect the composition accuracy and the user's chromatographic method. Some GPV designs utilize a reservoir diaphragm upstream of each inlet channel to mitigate the pressure pulses introduced by valve actuation. Although these reservoir chambers improve performance, the reservoir chambers are expensive, require a lot of space in the manifold, and limit design freedom. As flow rates increase, there may also be limitations on the effectiveness of the reservoir chambers.

[0007] Therefore, an improved GPV that reduces or attenuates unwanted pressure pulses is well received in the art. Summary of the invention

[0008] In one embodiment, a gradient proportional valve for liquid chromatography includes: a plurality of inlet ports configured to receive a plurality of fluids; a manifold connected to each of the plurality of inlet ports, the inlet ports configured to mix the plurality of fluids in a controlled manner to provide a fluid composition, the manifold including a plurality of conduits within the manifold, each of the plurality of conduits receiving the fluid through a corresponding one of the plurality of inlet ports; an actuating mechanism having a piston located within a bore structure surrounding the piston, the actuating mechanism configured to open and close at least one of the plurality of conduits in a controlled manner, wherein the piston and the bore structure have a close tolerance configured to create a fluid tight seal when the actuating mechanism closes at least one of the plurality of conduits; and a common outlet port configured to receive the fluid composition.

[0009] Additionally or alternatively, the gradient proportioning valve further comprises an individual actuation mechanism for each of the respective plurality of conduits, each of the individual actuation mechanisms having a piston positioned within a bore having a close tolerance configured to create a fluid tight seal.

[0010] Additionally or alternatively, the piston and the bore create a fluid tight seal without a deformable sealing element.

[0011] Additionally or alternatively, the actuating mechanism is a solenoid valve.

[0012] Additionally or alternatively, the piston is made of ceramic.

[0013] Additionally or alternatively, the actuation mechanism is configured to open and close two or more of the plurality of conduits.

[0014] Additionally or alternatively, the piston is configured to rotate about the drilling structure to open and close at least one of the plurality of conduits in a controlled manner.

[0015] Additionally or alternatively, the piston is configured to rotate less than 90 degrees to open and close at least one of the plurality of conduits in a controlled manner.

[0016] Additionally or alternatively, the piston comprises a flat surface keyed into one side.

[0017] Additionally or alternatively, the piston extends axially along a length, wherein the piston includes a bore extending axially within the piston, the bore being configured to receive fluid from the piston and to discharge fluid.

[0018] Additionally or alternatively, the close tolerances produce a gap of 5 microns or less between the piston and the bore structure.

[0019] Additionally or alternatively, the piston is configured to move axially within the borehole structure to open and close at least one of the plurality of conduits in a controlled manner.

[0020] Additionally or alternatively, the piston is configured to move axially and rotate relative to the drilling structure.

[0021] In another embodiment, a method for mixing fluids includes providing a gradient proportional valve, the gradient proportional valve including a manifold having a plurality of conduits; receiving a plurality of fluids in a plurality of inlet ports of the gradient proportional valve; opening and closing each of the plurality of conduits in a controlled manner by an actuating mechanism having a piston, the piston being located within a bore structure surrounding the piston; maintaining a fluid tight seal between the piston and the bore structure during opening and closing, wherein the piston and the bore structure have a tight tolerance configured to produce a fluid tight seal; mixing the plurality of fluids in a controlled manner within the manifold of the gradient proportional valve; and outputting the fluid composition from a common outlet port of the gradient proportional valve.

[0022] Additionally or alternatively, the method further includes preventing unwanted fluid pressure pulses in the manifold via the actuation mechanism by minimizing internal fluid volume within the piston and the drilling structure.

[0023] Additionally or alternatively, the actuating mechanism is made of ceramic.

[0024] Additionally or alternatively, the method further comprises opening two or more of the plurality of conduits by an actuation mechanism.

[0025] Additionally or alternatively, the method further comprises rotating the piston about the drilling structure to open and close at least one of the plurality of conduits in a controlled manner.

[0026] Additionally or alternatively, the method further comprises axially moving a piston within the borehole structure to open and close at least one of the plurality of conduits in a controlled manner.

[0027] Additionally or alternatively, the method further comprises moving the piston both axially and rotationally relative to the drilling structure.

[0028] In another embodiment, a liquid chromatography system includes: a gradient proportional valve for liquid chromatography, the gradient proportional valve including: a plurality of inlet ports, the plurality of inlet ports being configured to receive a plurality of fluids; a manifold, the manifold being connected to each of the plurality of inlet ports, the inlet ports being configured to mix the plurality of fluids in a controlled manner to provide a fluid composition, the manifold including a plurality of conduits inside the manifold, each of the plurality of conduits receiving the fluid through a corresponding one of the plurality of inlet ports; an actuating mechanism having a piston, the piston being located within a drilling structure surrounding the piston, the actuating mechanism being configured to open and close at least one of the plurality of conduits in a controlled manner, wherein the piston and the drilling structure have a close tolerance, the close tolerance being configured to create a fluid tight seal when the actuating mechanism closes at least one of the plurality of conduits; and a common outlet port, the common outlet port being configured to receive the fluid composition; an injector; a separation column; and a detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other advantages of the present invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which the same reference numerals refer to the same elements and features in each of the drawings. For clarity, not every element is labeled in every drawing. The drawings are not necessarily drawn to scale, but emphasis is placed on illustrating the principles of the present invention.

[0030] Figure 1 Depicted is a schematic diagram of a liquid chromatography apparatus according to one embodiment.

[0031] Figure 2 Depicted is a perspective view of a gradient proportioning valve according to one embodiment.

[0032] Figure 3 Depicted is a Figure 2 Side cross-sectional view of a gradient proportional valve.

[0033] Figure 4 Depicted is a Figure 2-Figure 3 Schematic diagram of a gradient proportional valve.

[0034] Figure 5 Depicted is a schematic cross-sectional view of an actuation mechanism for switching a valve according to one embodiment.

[0035] Figure 6 Depicted is a schematic cross-sectional view of an actuation mechanism for switching a valve according to one embodiment.

[0036] Figure 7 Depicted is a schematic cross-sectional view of an actuation mechanism for switching a valve according to one embodiment.

[0037] Figure 8Depicted is a schematic cross-sectional view of an actuation mechanism for switching a valve according to one embodiment.

[0038] Fig. 9 Depicted is a schematic diagram of a gradient proportioning valve according to one embodiment.

[0039] Fig.10 Depicted is a schematic cross-sectional view of an actuation mechanism for switching a valve according to one embodiment.

[0040] Fig.11 Depicted is a schematic cross-sectional view of an actuation mechanism for switching a valve according to one embodiment.

[0041] Fig.12 Depicted is a schematic cross-sectional view of an actuation mechanism for switching a valve according to one embodiment.

[0042] Fig.13 Depicted is a schematic diagram of a gradient proportioning valve according to one embodiment.

[0043] Fig.14 Depicted is a schematic cross-sectional view of an actuation mechanism for switching a valve according to one embodiment. DETAILED DESCRIPTION

[0044] Reference in this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present teachings. References to specific embodiments within this specification are not necessarily all referring to the same embodiment.

[0045] The gradient proportioning valve accommodates a fluid flow from an external reservoir into the valve for mixing in appropriate proportions to form a liquid composition in a liquid chromatography. The gradient proportioning valve described herein includes an inlet conduit connected to one or more inlet valves that are usually closed. The actuating mechanism can be switched open in a controlled manner to provide the appropriate amount of fluid required when mixing the liquid composition. The function of the entire valve is to provide a continuous flow of a synthetic accurate mixture of components, such as a solvent in a high pressure liquid chromatography (HPLC) embodiment. The mixture can be provided from a common outlet under flow conditions without interfering with the flow rate of the fluid input system, and without changing or otherwise affecting the quality / composition of the fluid input for mixing.

[0046] Embodiments of the gradient proportional valve described herein can be configured to attenuate or otherwise reduce pressure pulses that occur due to the opening and closing of passages in the fluid system of the valve and in the valve itself. Such pressure pulses have been found to cause larger sinusoidal oscillations in composition errors. Therefore, the gradient proportional valve described herein can be configured to provide improved composition accuracy over the entire solvent composition range. Such improved composition accuracy may be particularly important at higher flow rates.

[0047] In the embodiment of the gradient proportional valve described herein, one or more actuating mechanisms for opening and closing the inlet conduit each include a plunger or piston mechanism operating in conjunction with a drilling structure. By manufacturing a plunger and a drilling structure with very close tolerances, a seal is formed when the plunger is inserted into the drilling structure. Using a plunger and a drilling structure of high precision size as a sealing mechanism, the gradient proportional valve reduces or minimizes the volume of liquid storage in the gradient proportional valve, and makes the pressure pulse downstream of the actuating mechanism very small or without a pressure pulse. As described herein, a close tolerance describes the tolerance in the case where the gap between the plunger and the drilling structure may be less than 6 microns. For example, in some embodiments, it is envisioned that the gap between the plunger and the drilling structure is between 2 microns and 5 microns. This close tolerance and low gap can provide a fluid-tight seal without the need to deploy a deformable sealing element or other seals. In addition, the embodiments herein envision that ceramic materials are used for pistons and / or surrounding drilling structures.

[0048] Figure 1 is a block diagram of an exemplary liquid chromatography system 100 suitable for preparative or industrial liquid chromatography according to one embodiment of the present invention. System 100 is an exemplary system that may include a gradient proportional valve according to the embodiments described herein. Apparatus 100 includes four solvent reservoirs 1A, 1B, 1C, 1D; a gradient proportional valve 2; an inlet manifold valve 3; a pump 4; a solvent mixer 5; an injector 8; a separation column 6; a detector 7 and a control unit 9. Gradient proportional valve 2 represents a valve that includes one or more of the damping features described herein. Thus, gradient proportional valve 2 may be Figure 2-Figure 12 Any of the gradient proportioning valves shown in and described below.

[0049] In operation, the gradient proportioning valve 2 and the pump 4 select and extract one or more solvents from the reservoirs 1A, 1B, 1C, 1D in response to the control of the control unit 9. The gradient proportioning valve 2 can be operated in response to the control of the control unit 9 to provide a selected solvent composition, which is optionally changed over time, such as to implement gradient mode chromatography. The solvent mixer 5 is any suitable mixer, including known passive and active mixers. The ejector is any suitable ejector 8, including known ejectors, for injecting the sample into the solvent stream. The ejector 8 is optionally placed at an alternative position in the solvent flow path, as will be understood by those of ordinary skill in the art of liquid chromatography. The inlet manifold valve 3 is connected to the outlet pipe from the gradient proportioning valve 2, and is connected to two inlet pipes connected to the pump 4 to supply the solvent to the two piston chambers. The inlet manifold valve 3 optionally includes a sample ejector to inject the sample into the solvent before the sample enters the pump 4. The control unit 9 (comprising, for example, a personal computer or workstation) receives data and / or provides control signals to, for example, the gradient proportional valve 2, the pump inlet manifold 3, the pump 4, and / or the detector 7 via wired and / or wireless communication. The control unit 9 supports, for example, the automation of sample processing. In various illustrative embodiments, the control unit 9 is implemented in software, firmware, and / or hardware form (e.g., as an application specific integrated circuit). The control unit 9 includes a storage component and / or communicates with one or more storage components.

[0050] Suitable implants of the control unit 9 include, for example, one or more integrated circuits, such as microprocessors. In some alternative embodiments, a single integrated circuit or microprocessor includes the control unit 9 and other electronic parts of the device 100. In some embodiments, the one or more microprocessors implement software that enables the functions of the control unit 9. In some embodiments, the software is designed to run on general-purpose equipment and / or dedicated processors dedicated to the functions described herein.

[0051] In some embodiments of system 100, control unit 9 includes user interface to support the interaction with control unit 9 and / or other parts of system 100. For example, interface is configured to accept control information from user and provide information about system 100 to user. User interface is for example used to set system control parameters and / or provide diagnosis and troubleshooting information to user. In one embodiment, user interface provides networked communication between system 100 and user located in operating environment local or away from operating environment. In some embodiments, user interface is used to modify and update software. In view of the description of illustrative embodiments provided herein, it is obvious to those of ordinary skill in separation field that various other configurations and embodiments of control unit can be utilized in other embodiments of the present invention to provide automatic control of industrial and preparative chromatography.

[0052] Pump 4 can be configured to provide solvent at a pressure of at least 500psi, or 1.000psi, or 5.000psi, 10.000psi or greater. Pumps include any suitable piston-based pumps, including known pumps, such as those available from Waters Corporation, Milford, Mass. Column 6 is any column suitable for industrial and preparative chromatography. The column contains any medium suitable for such purposes, including known media. The adsorbent material is selected from any suitable adsorbent material, including known materials such as mixtures of silicon dioxide or silicon dioxide and copolymers of, for example, alkyl compounds. Solvent is any solvent suitable for the desired separation process, including known solvents.

[0053] Likewise, the system 100 described above is intended to be an exemplary liquid chromatography system in which various embodiments of gradient ratio valves may be deployed. However, the gradient ratio valve described herein may be implemented in any system that performs gradient fluid mixing. For example, in a liquid chromatography quaternary system, after solvent reservoirs 1A, 1B, 1C, 1D, the next component that the solvent enters may be a degassing chamber. The solvent may enter the gradient ratio valve 2 from the degassing chamber. After the gradient ratio valve 2, the solvent may then pass through the check valve to reach the pump (i.e., no inlet manifold valve is required). It is contemplated that any liquid chromatography system configuration that deploys a gradient ratio valve is used to incorporate the principles described herein.

[0054] Reference now Figure 2 , shows a perspective view of a gradient proportional valve 2A according to one embodiment. The gradient proportional valve 2A includes a reservoir 19A, 19B positioned directly adjacent to the switching valves 17A, 17B, the reservoir being located on the side closest to the reservoirs 10A, 10B. It should be understood that an embodiment of the gradient proportional valve 2A may include two additional reservoirs and switching valves (not shown) located on the two open sides of the gradient proportional valve 2A, thereby connecting the gradient proportional valve 2 to the two additional reservoirs, for example Figure 1 1C, 1D shown in the figure. Each of the reservoirs 19A, 19B can include a soft-walled flexible plastic tube 50 of generally circular cross-section. As shown, the reservoir 50 can be adapted to be located at the end closest to the valve inlet to slide snugly over the rigid plastic connector 52. A connecting tube 54 can be implemented at the opposite end of the reservoir tube to maintain a relatively long length of flow tube 56 connecting the valve to the reservoir 1A, 1B. The end of the reservoir tube adjacent the connecting tube can be made to present a cross-section of a generally flat ellipse 55, which can allow significant internal volume changes to occur in the reservoir tube with little pressure change, thereby allowing the reservoir to overcome the effects of hydraulic inertia.

[0055] Figure 3 Depicted is a Figure 2 1 is a side cross-sectional view of a gradient proportioning valve 2A. The gradient proportioning valve 2A includes a valve manifold 10 that accommodates fluid flows from an external reservoir (not shown). For clarity of the discussion below, the illustrative valve described herein has the ability to mix only two input fluid flows. However, the features described herein can be applied to valve mixing, for example, four or more input fluid flows. The input fluid flow to be mixed is received from the reservoir and introduced into the valve at the inlet port 12. As is known in the art, a fluid from a corresponding reservoir (such as a solvent used in HPLC) flows into the corresponding inlet port 12 and thereafter flows through a corresponding inlet conduit 14 in the manifold 10 into a corresponding reservoir volume or chamber 16. Although Figure 3 The embodiment shown in includes a reservoir volume or chamber 16, but other embodiments contemplated herein may not include a reservoir chamber 16. Such embodiments may include an inlet port that provides fluid directly to the switching valves 17A, 17B without first passing through a reservoir chamber.

[0056] As shown, the integrated reservoir chamber 16, as well as the inlet port 12 and the inlet conduit 14, are appropriately sized as the flow rate of the valve application varies. The chamber 16 is tapered, with a conical base opposite the inlet conduit 14. The chamber is shaped to maximize the surface area of ​​the diaphragm (for compliance), and the inlet conduit 14 is positioned to allow for optimal swept volume geometry. Therefore, the chamber 16 also has a smooth transition from a larger cross-section to a smaller cross-section. The placement of the chamber minimizes fluid resistance between the switching valves 17A, 17B and the reservoir. The fluid flowing through the conduit 14 flows into the chamber 16 perpendicular to the tapered base to constrain the base or back of the chamber 16.

[0057] The reservoir diaphragm 18 is disposed at the conical base or back side of the chamber 16, opposite the inlet conduit 14. The diaphragm 18 in this illustrative embodiment is a 0.002 inch thick membrane formed of polytetrafluoroethylene (PTFE) with fluorinated ethylene propylene (FEP) laminated on each side. The diaphragm 18 acts as a membrane or compliant member on the back side of the reservoir chamber 16 to allow internal volume changes to occur in the chamber with small changes in pressure.

[0058] An oversized hole 20 behind the conical base or back side of the reservoir chamber 16 is configured to receive the diaphragm 18 to tightly clamp and seal the diaphragm in the reservoir chamber. A seating surface 22 inside the hole 20 provides an abutment against which the diaphragm seats. A sealing groove 24 is disposed in the seating surface 22 and provides a portion of the single seal implemented in an embodiment according to the present invention. A cylindrical sealing plug 26 formed of stainless steel includes a sealing ridge 28 that fits tightly into the sealing groove 24 to seal the diaphragm in the hole 20 when the plug 26 is engaged against the seating surface 22, with the diaphragm sandwiched between the plug and the seating surface.

[0059] Preferably, the sealing plug 26 is sized to fit tightly but slidably within the bore 20. The plug 26 is held in place by a clamping plate 30, which is mechanically attached to the valve manifold by screws 32. Additional mounting holes 33 are provided in the clamping plate 30 to facilitate mechanical fastening of the clamping plate to the valve manifold 10. In this illustrative embodiment, a resilient member, such as a disc spring 34 or a washer, is disposed between the sealing plug 26 and the clamping plate 30 to provide some resiliency.

[0060] The diaphragm can overcome hydraulic inertia while minimizing the volume of fluid in the valve exposed to potential air infiltration by limiting the surface area of ​​the diaphragm exposed to ambient air. An atmospheric port 36 is provided in the clamping plate 30 to allow ambient air to be present at the back side of the diaphragm 18. When exposure of the diaphragm to ambient air is desired, the reduced exposed surface area inside the atmospheric port significantly limits air infiltration through the diaphragm.

[0061] Thus, in operation, an input fluid stream to be mixed is received from a reservoir and introduced into the valve manifold 10 at the inlet port 12. The fluid from the respective reservoir flows into the respective inlet port 12 and thereafter flows through the respective inlet conduit 14 in the manifold 10 into the respective reservoir volume or chamber 16. The fluid to be mixed flows out of the chamber 16 through the chamber port 38 so that the fluid is available at the switching valves 17A, 17B. The switching valves 17A, 17B operate according to the principles of the present invention as described below. The controlled switching of the switching valves 17A, 17B determines the ratio of the respective fluids in the common port 42 within the receiving valve manifold 10. The respective fluids are mixed in their respective ratios in the common port 42 and are available at the outlet port 44 for downstream processing as known in the art.

[0062] Despite Figure 3Only two input valve embodiments are described in the present invention, but it should be understood that the concepts according to the present invention can be implemented in valves having any number of inlet ports for mixing liquid compositions. In addition, although the embodiments described herein include a single switching valve 17A, 17B for each inlet port 12, in other embodiments, a single switching valve 17A, 17B can be operated to open and close multiple inlet ports 12, as described below.

[0063] Figure 4 A schematic diagram of another gradient proportional valve 2B according to one embodiment is depicted. The gradient proportional valve 2B is schematically shown to include four separate inlet ports 12 that are connected to a reservoir chamber 16 (e.g. Figure 3 The chamber 16 shown provides fluid. Figure 3 Different, in Figure 4 In the embodiment shown, there are four separate reservoir chambers 16 to accommodate the four inlet ports 12. In addition, there is a separate switching valve 17A, 17B, 17C, 17D downstream of each of the reservoir chambers 16. Each of the four switching valves 17A, 17B, 17C, 17D individually exports fluid to a downstream mixing point 50 where the fluids are combined into a single stream. Downstream of the mixing point 50 there is an outlet 44.

[0064] Figure 4 An exemplary schematic diagram of a gradient proportioning valve 2B is shown, wherein each inlet channel includes its own valve 17A, 17B, 17C, 17D. In addition, the schematic diagram shows a reservoir chamber 16 for each inlet port 12. In other contemplated embodiments, a reservoir chamber 16 may not be required prior to the mixing valves 17A, 17B, 17C, 17D. In still other embodiments (such as those described below), the reservoir chamber and switching valve combination can be configured to receive more than one inlet, such as a single reservoir chamber and switching valve for two or more inlets. However, for Figure 4 The embodiment shown in FIG. 1 shows a case where a single actuation mechanism can be used for each inlet port. This schematic diagram can be used to describe the Figure 5-Figure 8 An embodiment of an actuation mechanism consistent with that shown in and described below.

[0065] Several embodiments of an actuation mechanism for a switching valve, such as one of the switching valves 17A, 17B, 17C, 17D described above, are described below. Figure 5-Figure 9 , Fig.11 , Fig.12 and Fig.14The described embodiments of the actuating mechanism for switching valves can be implemented via any switching valve mechanism configured to move a piston relative to a drilling structure or a cylinder. For example, the rotational movement of the piston relative to the drilling structure can be actuated by a stepper motor, a servo motor, or any other rotary actuator. The axial movement can be controlled by a solenoid, a voice coil, a piezoelectric actuator, or any other axial actuator. In addition, although the embodiments below describe various forms of actuating mechanisms for switching fluid flow, other embodiments consistent with the principles described herein are contemplated.

[0066] In addition, the embodiments described below can use ceramic materials for pistons and / or drilling structures. Pistons and drilling structures with close tolerances can be manufactured to produce gaps less than 6 microns. Close tolerances can provide fluid-tight seals between the conduits of the actuating mechanism without the need to use additional deformable sealing elements between components. Depending on the exact requirements of a particular design, the tolerances and material properties of the embodiments described herein can be changed. For example, the selection of operating pressure, piston and / or hole size, material, etc. may all affect the ability to achieve sealing without using external sealing components (e.g., deformable seals) via precision machined components.

[0067] In the embodiments described herein, ceramic materials can be particularly advantageous due to their ability to be manufactured with extremely tight tolerances. In addition, the high hardness of ceramics, as well as the wear, corrosion, and oxidation resistance of ceramics, can make ceramic materials particularly advantageous. Ceramics can also prevent the introduction of undesirable temperature effects. However, other chemically inert metals or other materials are contemplated. Examples of other materials can include stainless steel, such as Nitronic 60; titanium; nickel-cobalt alloys, such as MP35N ® ; Tantalum, etc.

[0068] The bore structure in the following embodiments is shown as having various inlet and outlet conduits that allow fluid to flow through the piston footprint of the actuating mechanism. Figure 5-Figure 9 , Fig.11 , Fig.12 and Fig.14 , but it should be understood that a manifold or housing can be attached to the exterior of the borehole structure of each embodiment for connecting an external fluid conduit thereto. Such a manifold or housing can be made of different materials, such as plastic, for example. The borehole structure can be accommodated in a plastic manifold in a variety of ways, including but not limited to being pressed, heat shrinking the plastic manifold around the holes, etc. Accommodating the borehole structure in this manner can provide ease of connecting and aligning the ceramic (or other material) inlet and outlet with the inlet and outlet channels of the solvent line in the liquid chromatography system.

[0069] In addition, although the following Figure 5-Figure 9 , Fig.11 , Fig.12 and Fig.14 Embodiments are described in which the pistons and corresponding drilling structures are cylindrical in shape and structure, but it is also contemplated that the pistons and drilling structures described herein can take the form of various shapes not limited to cylinders. In addition, although the pistons are described as moving parts in the embodiments described below, it should also be understood that the drilling structures can be moving parts rather than the pistons. It should be understood that the embodiments contemplated herein require relative movement between the pistons and their corresponding drilling structures, but movement of either or both of these components can produce the necessary relative movement.

[0070] Although not shown in the cross-sectional views below, the actuation mechanisms described herein may utilize one or more hard stop features to facilitate alignment between the pistons and their corresponding bore structures and to help control and prevent unwanted movement. In embodiments utilizing hard stop features, impact absorbing materials may be added to any of these hard stop features to reduce wear.

[0071] Reference now Figure 5 , depicts a schematic cross-sectional view of an actuating mechanism 200 for switching a valve according to one embodiment. The actuating mechanism 200 includes a piston 210 located within a bore structure 212. An inlet conduit 214 and an outlet conduit 216 provide fluid through the actuating mechanism 200. The piston 210 includes a key flat surface 220 cut therefrom, which forms an open space 218 between the piston 210 and the bore structure 212. Although a space is shown between the piston 210 and the bore structure 212, it should be understood that the present invention contemplates utilizing a very tight gap between the piston 210 and the bore structure 212, so that there is almost no space between them. Likewise, a gap of less than 6 microns is contemplated so as to maintain a fluid tight seal when the piston 210 rotates to close one or more of the inlet and outlet conduits 214, 216 without the use of any external sealing components or deformable seals.

[0072] Although only a top cross-sectional view of the actuation mechanism 200 is shown, it should be understood that the actuation mechanism includes an appropriate depth to accommodate the inlet and outlet conduits 214, 216 and to accommodate the attachment of the piston 210 to the motor to achieve rotational movement. Although the depth of the piston 210 and the bore structure 212 can be greater than the amount required to accommodate the inlet and outlet conduits 214, 216, the key flat surface 220 and the open space 218 can be specifically designed to correspond to the depth required to accommodate the inlet and outlet conduits 214, 216 to minimize the volume of the open space 218.

[0073] The actuation mechanism 200 may be configured to open and close the inlet conduit 214 and the outlet conduit 216 via rotation of the piston 210 about the bore structure 212 . Figure 5 The position in FIG. 2 shows the actuation mechanism 200 in an open state, whereby fluid can flow through the inlet 214 into the open space 218 created by the key flat surface 220 of the piston 210. Clockwise rotation from this open position will close the inlet conduit 214, while counterclockwise rotation will close the outlet. The actuation mechanism 200 can deploy any of these rotations to achieve the opening and closing of the conduits 214, 216. In addition, an angle θ is shown, which defines the rotational distance between the inlet conduit 214 and the outlet conduit 216. It may be desirable to include a relatively small angle θ, such as less than 90 degrees, in order to reduce the size of the open space 218 in the system. Reducing the size of this open space 218 and quickly opening and closing the inlet via a small angle θ can help reduce or eliminate pressure pulses generated by the actuation mechanism 200.

[0074] Figure 6 A schematic cross-sectional view of another actuation mechanism 300 for switching a valve according to one embodiment is depicted. The actuation mechanism 300 includes a piston 310 located within a bore structure 312. An inlet conduit 314 and an outlet conduit 316 provide fluid through the actuation mechanism 300. The piston 310 includes a conduit 318 extending through the piston to connect the inlet conduit 314 with the outlet conduit 316 when the piston 310 is in the relative position of the bore structure 312 shown. As with the previous embodiment, a gap of less than 6 microns is envisioned between the piston 310 and the bore structure 312 to maintain a fluid tight seal when the piston 310 rotates to close the inlet conduit 314 and the outlet conduit 316 without the use of any external sealing components or deformable seals.

[0075] Although only a top cross-sectional view of the actuation mechanism 300 is shown, it should be understood that the actuation mechanism includes appropriate depth to accommodate the inlet conduit 314 and the outlet conduit 316 and to accommodate the attachment of the piston 310 to the motor to achieve rotational movement. The actuation mechanism 300 can be configured to open and close the inlet conduit 314 and the outlet conduit 316 by rotation of the piston 310 about the drilling structure 312 in either direction relative to the position shown. Figure 6The position in FIG. 2 shows the actuator 300 in an open state, whereby fluid can flow from the inlet conduit 314 through the conduit 318 of the piston 310 and out of the actuator 300 through the outlet conduit 316. The actuator 200 can be deployed by rotating clockwise or counterclockwise to achieve opening and closing. In addition, the angle θ between the inlet conduit 314 and the outlet conduit 316 is shown as 180 degrees, and a straight line is generated by the actuator 300 when the actuator 300 is opened. Such embodiments can reduce the amount of rotation required to open and close the valve. However, only when each actuator 300 has a single inlet and a single outlet, including this straight line method is feasible.

[0076] Figure 7 A schematic cross-sectional view of another actuation mechanism 400 for switching a valve according to one embodiment is depicted. The actuation mechanism 400 includes a piston 410 located within a bore structure 412. An inlet conduit 414 and an outlet conduit 416 provide fluid through the actuation mechanism 400. The piston 410 includes a conduit 418 extending through the piston to connect the inlet conduit 414 with the outlet conduit 416 when the piston 410 is in the relative position of the bore structure 412 shown. The conduit 418 of the piston 410 can be designed to drill two vertical holes into the piston 410 that are 90 degrees apart and meet in the middle of the piston 410. As with the previous embodiment, a gap of less than 6 microns is envisioned between the piston 410 and the bore structure 412 to maintain a fluid tight seal when the piston 410 rotates to close the inlet conduit 414 and the outlet conduit 416 without the use of any external sealing components or deformable seals.

[0077] Although only a top cross-sectional view of the actuation mechanism 400 is shown, it should be understood that the actuation mechanism includes appropriate depth to accommodate the inlet conduit 414 and the outlet conduit 416 and to accommodate the attachment of the piston 410 to the motor to achieve rotational movement. The actuation mechanism 400 can be configured to open and close the inlet conduit 414 and the outlet conduit 416 by rotation of the piston 410 about the drilling structure 412 in either direction relative to the position shown. Figure 7 The position in FIG. 4 shows the actuator 400 in an open state, whereby fluid can flow from the inlet conduit 414 through the conduit 418 of the piston 410 and out of the actuator 400 through the outlet conduit 416. The actuator 400 can be deployed in a clockwise or counterclockwise rotation to achieve opening and closing. In addition, the angle θ between the inlet conduit 414 and the outlet conduit 416 is shown as 90 degrees, thereby creating a vertical angle within the piston 410 that the fluid must flow through to flow out of the outlet conduit 416 when the actuator 400 is open. This change in flow direction may be desirable in reducing the pressure pulse of opening and closing downstream of the actuator 400. This embodiment may be similar to Figure 6The implementation scheme works, thereby relative to Figure 5 In the embodiment of the present invention, the amount of rotation required to open and close the valve is reduced. However, this method is only feasible when there is a single inlet and a single outlet for each actuation mechanism 300.

[0078] Figure 8 A schematic cross-sectional view of another actuation mechanism 500 for switching a valve according to one embodiment is depicted. The actuation mechanism 500 includes a piston 510 located within a bore structure 512. An inlet conduit 514 and an outlet conduit 516 provide fluid through the actuation mechanism 500. The piston 510 includes a conduit 518 extending through the piston to connect the inlet conduit 514 with the outlet conduit 516 when the piston 510 is in the relative position of the bore structure 512 shown. As with the previous embodiment, a gap of less than 6 microns is envisioned between the piston 510 and the bore structure 512 to maintain a fluid tight seal when the piston 510 moves to close the inlet conduit 514 and the outlet conduit 516 without the use of any external sealing components or deformable seals. Unlike the previous embodiment, the movement of the actuation mechanism 500 to open and close the piston 410 relative to the bore structure 512 is axial rather than rotational.

[0079] Although only a side cross-sectional view of the actuation mechanism 500 is shown, it should be understood that the actuation mechanism includes appropriate depth to accommodate the inlet and outlet conduits 514, 516 and to accommodate the attachment of the piston 510 to the motor to achieve axial movement. The actuation mechanism 500 can be configured to open and close the inlet and outlet conduits 514, 516 via axial movement of the piston 510 relative to the drilling structure 512 in either direction relative to the position shown. Figure 6 The position in FIG. 5 shows the actuator 500 in an open state, whereby fluid can flow from the inlet conduit 514 through the conduit 518 of the piston 510 and out of the actuator 500 through the outlet conduit 516. Although the previous embodiments may deploy rotary movement via a stepper motor, servo motor, or other rotary actuator, Figure 8 The embodiment shown in can be controlled via solenoids, voice coils, piezoelectric motors, or other axial movement systems.

[0080] Fig. 9Describe the schematic diagram of another gradient proportional valve 2C according to an embodiment. Schematically show the gradient proportional valve 2C, the gradient proportional valve includes four separate inlet ports 12, the inlet ports provide fluid to two separate switching valves 17A, 17B via conduits or channels. As shown, each switching valve 17A, 17B is configured to receive fluid from two separate inlet ports 12 and provide a single outlet from the corresponding switching valve 17A, 17B. The single outlets of the two separate switching valves 17A, 17B each export fluid to a downstream mixing point 50 separately. At the mixing point 50, the fluid is combined into a single stream from two separate streams received from the switching valves 17A, 17B. There is an outlet 44 downstream of the mixing point 50.

[0081] Fig. 9 An exemplary schematic diagram of a gradient proportional valve 2C is shown, in which two inlet channels are connected to one valve 17A, 17B. In addition, the schematic diagram does not show the reservoir chamber 16. In other embodiments, a reservoir chamber may exist for each inlet port 12 before providing fluid to the switching valves 17A, 17B. The schematic diagram with two inlet channels for each valve can be used to describe the same Figure 10-12 An embodiment of an actuation mechanism consistent with that shown in and described below.

[0082] Fig.10 A schematic cross-sectional view of another actuation mechanism 600 for switching a valve according to one embodiment is depicted. The actuation mechanism 600 includes a piston 610 located within a borehole structure 612. A first inlet conduit 614 and a second inlet conduit 616 provide fluid to the actuation mechanism 600 from different fluid sources. The piston 610 includes a conduit 618 extending from the outside of the piston 610 into the middle of the piston 610. An outlet conduit 620 is drilled axially from the piston 610 to allow fluid to flow out of the actuation mechanism 600. As with the previous embodiment, a gap of less than 6 microns is envisioned between the piston 610 and the borehole structure 612 to maintain a fluid tight seal when the piston 610 rotates to close the inlet conduit 414 and the outlet conduit 416 without the use of any external sealing components or deformable seals.

[0083] Although only a top cross-sectional view of the actuator mechanism 600 is shown, it should be understood that the actuator mechanism includes appropriate depth to accommodate the inlet conduit 614 and the outlet conduit 616, to accommodate the attachment of the piston 610 to the motor to achieve rotational movement, and to accommodate connecting the outlet 620 of the piston 610 to the rest of the downstream liquid chromatography system.

[0084] The actuation mechanism 600 may be configured to open and close respective first and second inlet conduits 614 , 616 by rotating the piston 610 about the bore structure 612 . Fig.10The position in FIG. 6 shows the actuating mechanism 600 in the following state, wherein the first inlet conduit 614 is in an open state, whereby the fluid can flow from the inlet conduit 614 through the conduit 618 of the piston 610 and out of the axially drilled outlet conduit 620 of the piston 610. The actuating mechanism 600 can be deployed on the piston 610 with respect to the drilling structure 612 in a clockwise or counterclockwise rotation so as to achieve opening and closing. For example, clockwise rotation can move the piston 610 from opening the first inlet 614 to opening the second inlet 616. Alternatively, from the position shown, counterclockwise rotation can close both the first and second inlets 614, 616. In the embodiment shown, the closed state can also occur when the piston 610 rotates so that the outlet of the conduit 618 faces the wall of the drilling structure 612 located between the first inlet 614 and the second inlet 616. The present embodiment contemplates that the actuating mechanism 600 can switch between two separate inlets 614, 616, one of which is open at a given time, and thereby the actuating mechanism always includes the same outlet 620.

[0085] In addition, the angle θ between each of the first and second inlet conduits 614, 616 defines a rotational distance between the first inlet conduit 614 and the second inlet conduit 616. It may be desirable to include a relatively small angle θ, such as less than 90 degrees, to allow the actuation mechanism 600 to switch between positions more quickly. This can help reduce or eliminate pressure pulses generated by the actuation mechanism 600.

[0086] Fig.11 A schematic cross-sectional view of another actuation mechanism 700 for switching a valve according to one embodiment is depicted. The actuation mechanism 700 includes a piston 710 located within a borehole structure 712. A first inlet conduit 714 and a second inlet conduit 715 in the borehole structure 712 provide fluid to the actuation mechanism 700 from different fluid sources. The borehole structure 712 also includes an outlet conduit 716 located between the first inlet conduit 714 and the second inlet conduit 715. The piston 710 includes a key flat surface 720 cut therefrom, which forms an open space 718 between the piston 710 and the borehole structure 712. Although a space is shown between the piston 710 and the borehole structure 712, it should be understood that the present invention contemplates utilizing a very tight gap between the piston 710 and the borehole structure 712, such that there is almost no space between them. Likewise, a clearance of less than 6 microns is contemplated in order to maintain a fluid tight seal when the piston 710 rotates to close one or more of the inlet conduit 714 and the outlet conduits 715 , 716 without the use of any external sealing components or deformable seals.

[0087] Although only a top cross-sectional view of the actuator mechanism 700 is shown, it should be understood that the actuator mechanism includes appropriate depth to accommodate the inlet conduit 714 and the outlet conduit 716, to accommodate the attachment of the piston 710 to the motor to achieve rotational movement, and to accommodate connecting the outlet 720 of the piston 710 to the rest of the downstream liquid chromatography system.

[0088] The actuation mechanism 700 may be configured to open and close respective first and second inlet conduits 714 , 715 by rotating the piston 710 about the bore structure 712 . Fig.10 714. The position in FIG. 7 shows the actuation mechanism 700 in a state where the first inlet conduit 714 is in an open state, whereby fluid can flow through the inlet 714 into the open space 718 created by the key flat surface 720 of the piston 710. Clockwise or counterclockwise rotation from this open position will close the first inlet conduit 714. Similarly, rotating the piston 710 clockwise so that the key flat surface 720 extends between the second inlet conduit 715 and the outlet conduit 716 will open the second inlet conduit 715 and close the first inlet conduit 714.

[0089] The actuation mechanism 700 may deploy any of these rotations to achieve opening and closing of the first and second inlet conduits 714, 715. In addition, angles θ between each of the first inlet conduit 714 and the outlet conduit 716 and between the second inlet conduit 715 and the outlet conduit 716 are shown. These angles θ define the rotation distance between the respective conduits 714, 715, 716. It may be desirable to include a relatively small angle θ, such as less than 90 degrees, in order to reduce the size of the open space 718 in the system. Reducing the size of this open space 718 and quickly opening and closing the inlet through a small angle θ can help reduce or eliminate pressure pulses generated by the actuation mechanism 700.

[0090] Fig.12 A schematic cross-sectional view of another actuation mechanism 800 for switching a valve according to one embodiment is depicted. The actuation mechanism 800 includes a piston 810 located within a borehole structure 812. A first inlet conduit 814 and a second inlet conduit 816 provide fluid from the borehole structure 812 to the piston 810. A combined outlet conduit 818 allows the fluid to leave the actuation mechanism 800. The piston 810 includes a conduit 820 extending through the piston to connect the second inlet conduit 816 with the outlet conduit 818 when the piston 810 is in the relative position of the borehole structure 812 shown. The piston 810 can be moved axially to the left to connect the first inlet conduit 814 to the outlet conduit 818. Alternatively, the piston can be moved axially to the right to close each of the first and second inlet conduits 814, 816.

[0091] As with the previous embodiments, a gap of less than 6 microns is contemplated between the piston 810 and the bore structure 812 to maintain a fluid tight seal when the piston 810 moves to open or close the inlet conduit 814 and the outlet conduit 816 without the use of any external sealing components or deformable seals. Fig.11 Unlike the embodiment shown in , the movement of the piston 810 relative to the drilling structure 512 is axial rather than rotational to open and close the two inlet conduits 814, 816 via the actuation mechanism 800.

[0092] Fig.13 Described is a schematic diagram of another gradient proportional valve 2D according to an embodiment. Schematically illustrated is a gradient proportional valve 2D, which includes four separate inlet ports 12, which provide fluid to a single switching valve 17A via a conduit or channel. As shown, the switching valve 17A is configured to receive fluid from each of the four separate inlet ports 12 and provide a single outlet from the switching valve 17A. The downstream of the single switching valve may be a downstream mixing point 50, which may be a larger volume area that helps to mix fluids after the switching valve 17A but before the outlet. The mixing point 50 may be incorporated into the actuating mechanism of the switching valve 17A instead of a separate volume chamber. There is an outlet 44 downstream of the mixing point 50.

[0093] Fig.13 An exemplary schematic diagram of a gradient proportional valve 2D is shown, in which all four inlet channels are connected to a single switching valve 17A. In addition, the schematic diagram does not show the reservoir chamber 16. In other contemplated embodiments, a reservoir chamber may be present for each inlet port 12 before providing fluid to the switching valve 17A. The schematic diagram with four inlet channels for each valve may be used to describe the following description of Fig.14 An embodiment consistent with the actuation mechanism shown in .

[0094] Fig.14A schematic cross-sectional view of another actuation mechanism 900 for switching valves according to one embodiment is depicted. The actuation mechanism 900 includes a piston 910 located within a borehole structure 912. A first inlet conduit 914, a second inlet conduit 916, a third inlet conduit 918, and a fourth inlet conduit 920 each provide fluid to the actuation mechanism 900 from a different fluid source. The piston 910 includes a conduit 922 extending from the outside of the piston 910 into the middle of the piston 910. An outlet conduit 924 is drilled axially from the piston 910 to allow fluid to flow out of the actuation mechanism 900. As with the previous embodiment, a gap of less than 6 microns is envisioned between the piston 910 and the borehole structure 912 to maintain a fluid tight seal when the piston 910 rotates to close the inlet and outlet conduits 914, 916, 918, 920 without the use of any external sealing components or deformable seals.

[0095] Although only a top cross-sectional view of the actuator mechanism 900 is shown, it should be understood that the actuator mechanism includes appropriate depth to accommodate inlet and outlet conduits 914, 916, 918, 920, to accommodate the attachment of the piston 910 to the motor to achieve rotational movement, and to accommodate connecting the outlet 924 of the piston 910 to the rest of the downstream liquid chromatography system.

[0096] The actuation mechanism 900 may be configured to open and close respective first, second, third, and fourth inlet conduits 914 , 916 , 918 , 920 via rotation of the piston 910 about the bore structure 912 . Fig.14 918. The position in FIG. 1 shows the actuation mechanism 900 in a state where the second inlet conduit 916 is in an open state, whereby fluid can flow from the second inlet conduit 916 through the conduit 922 of the piston 910 and out of the axially drilled outlet conduit 924 of the piston 910. The actuation mechanism 900 can be deployed on the piston 910 with respect to the drilling structure 912 in a clockwise or counterclockwise rotation to achieve the opening and closing of the various inlet conduits 914, 916, 918, 920. For example, a clockwise rotation can move the piston 910 from opening the second inlet conduit 916 to opening the third inlet conduit 918. Alternatively, from the position shown, a counterclockwise rotation can open the first inlet conduit 914. In the illustrated embodiment, the closed state may also occur when the piston 910 is rotated so that the outlet of the conduit 922 faces the wall of the bore structure 612, which is located between one of the inlet conduits 914, 916, 918, 920 or counterclockwise to the first inlet conduit 914 or clockwise to the fourth inlet conduit 920. The present embodiment contemplates that the actuation mechanism 600 is capable of switching between four separate inlets 914, 916, 918, 920, with one inlet being open at a given time, and thus the actuation mechanism always includes the same outlet 924.

[0097] In addition, the angle θ between each of the inlet conduits 914, 916, 918, 920 defines the rotational distance between the various inlet conduits 914, 916, 918, 920. It may be desirable to include a relatively small angle θ, such as less than 90 degrees, to allow the actuation mechanism 900 to switch between positions more quickly. This can help reduce or eliminate pressure pulses generated by the actuation mechanism 900.

[0098] Although the above embodiments have been described using either axial or rotational movement, it is contemplated that other embodiments for the actuation mechanism may use a combination of both axial and rotational movement. For example, it is contemplated that the inlets may actually be positioned axially spaced apart as well as rotationally spaced apart. For example, in Fig.14 In the embodiment shown, two inlets (e.g., inlet 916, 920) can be spaced axially relative to the other two inlets (e.g., inlet 914, 918), rather than having all four inlets reach the piston 910 at the same depth. Using both axial and rotational spacing can allow the total space between the various inlets to be reduced. For example, if the inlets 914, 916, 918, 920 are located at the corners of a diamond or square shape, the movement of the piston from any one inlet to another inlet will be nearly the same. Compared to the embodiment in which the inlets 914, 916, 918, 920 reach the piston 910 at a single plane that is separated by an angle θ, the movement between the inlet 914 and the inlet 920 is greater than the movement between the inlet 916 and the inlet 918. Various embodiments of the above-mentioned actuating mechanism with more than one inlet can use both rotation and axial movement in combination to reduce the space between the various inlets.

[0099] In addition, although the embodiment described above shows four inlet ports for each gradient proportioning valve 2D, the actuating mechanism described herein can be incorporated into a gradient proportioning valve with any number of inlets of any number of solvent lines. In addition, although the embodiment of the actuating mechanism shows a single inlet, two inlets or four inlets, the principle of the actuating mechanism described above can be applied to other number of inlets, such as three inlets or greater than 4 inlets. Regardless of the embodiment, the actuating mechanism envisioned herein can include a single outlet, regardless of how many inlets the actuating mechanism is configured to be used for.

[0100] Also contemplated is a method for operating a switching valve of a gradient proportional valve of a liquid chromatography system. For example, the method contemplated herein includes providing a gradient proportional valve, such as one of the valves 17A, 17B, 17C, 17D described herein, including a manifold with multiple conduits. The method includes receiving multiple fluids in multiple inlet ports of the gradient proportional valve, using an actuating mechanism with a piston to open and close each of the multiple pipelines in a controlled manner, the piston being located in a drilling structure surrounding the piston, the actuating mechanism being, for example, one of actuating mechanisms 200, 300, 400, 500, 600, 700, 800, 900, the piston being, for example, one of pistons 210, 310, 410, 510, 610, 710, 810, 910, the drilling structure being, for example, one of drilling structures 212, 312, 412, 512, 612, 712, 812, 912. The method includes maintaining a fluid tight seal between a piston and a bore structure during opening and closing, wherein the piston and the bore structure have close tolerances configured to produce the fluid tight seal. The method includes mixing a plurality of fluids in a controlled manner within a manifold of a gradient proportioning valve and outputting the fluid composition from a common outlet port of the gradient proportioning valve.

[0101] Another method includes preventing unwanted fluid pressure pulses in the manifold using an actuation mechanism by minimizing the internal fluid volume within the piston and drilling structure. In addition, the contemplated method includes using an actuation mechanism to open two or more conduits of the plurality of conduits, such as using Figure 9-Figure 14 The embodiment shown.

[0102] The method also includes rotating the piston about the drilling structure to open and close at least one of the plurality of conduits in a controlled manner, such as in Figure 5-Figure 7 , Fig.10 , Fig.11 and Fig.14 Alternatively, the method includes axially moving a piston within a borehole structure to open and close at least one of a plurality of conduits in a controlled manner, such as in Figure 8 and Fig.12 Alternatively, the method may include moving the piston both axially and rotationally relative to the drilling structure as described above.

[0103] While the present invention has been shown and described with reference to particular embodiments, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the invention as described in the following claims.

Claims

1. A gradient proportional valve for liquid chromatography, the gradient proportional valve comprising: a plurality of inlet ports configured to receive a plurality of solvents; a manifold connected to each of the plurality of inlet ports, the inlet ports configured to mix the plurality of solvents in a controlled manner to provide a solvent composition, the manifold comprising a plurality of conduits within the manifold, each of the plurality of conduits receiving a fluid through a corresponding one of the plurality of inlet ports; an actuation mechanism having a piston positioned within a bore structure surrounding the piston, the actuation mechanism being configured to open and close the plurality of conduits in a controlled manner, wherein the piston and the bore structure have close tolerances configured to create a fluid tight seal when the actuation mechanism closes the plurality of conduits, wherein the close tolerances create a gap between the piston and the bore structure of less than 6 microns; and a common outlet port configured to receive the solvent composition, wherein the gradient proportioning valve is configured to provide a continuous flow of an accurate mixture of components of the plurality of solvents, The piston and the bore structure create the fluid tight seal without the need for a deformable sealing element, The piston is configured to rotate about the drilling structure to open and close the at least one conduit of the plurality of conduits in the controlled manner, The piston extends axially along a length, wherein the piston includes a bore configured to receive a solvent from the piston and to flow the solvent out.

2. A gradient proportional valve according to claim 1, wherein the gradient proportional valve also includes a separate actuating mechanism for each of the corresponding plurality of conduits, each of the separate actuating mechanisms having a piston located within a drilling structure, the drilling structure having a tight tolerance configured to produce a fluid tight seal.

3. The gradient proportional valve according to claim 1, wherein: The actuating mechanism is a solenoid valve.

4. The gradient proportional valve according to claim 1, wherein: The piston is made of ceramic.

5. The gradient proportional valve according to claim 1, wherein: The actuation mechanism is configured to open and close two or more of the plurality of conduits.

6. The gradient proportional valve according to claim 1, wherein: The piston is configured to rotate less than 90 degrees to open and close the at least one conduit of the plurality of conduits in the controlled manner.

7. The gradient proportional valve according to claim 1, wherein: The piston includes a flat surface keyed into one side.

8. The gradient proportional valve according to claim 1, wherein: The bore extends axially within the piston.

9. The gradient proportional valve according to claim 1, wherein: The tight tolerances produce a gap of 5 microns or less between the piston and the bore structure.

10. The gradient proportional valve according to claim 1, wherein: The piston is configured to move axially within the drilling structure to open and close the at least one conduit of the plurality of conduits in the controlled manner.

11. The gradient proportional valve according to claim 1, wherein: The piston is configured to move axially and rotate relative to the drilling structure.

12. A method for mixing solvents in a liquid chromatography system, the method comprising: Providing a gradient proportioning valve according to claim 1, the gradient proportioning valve comprising a manifold having a plurality of conduits; receiving a plurality of solvents in a plurality of inlet ports of the gradient proportioning valve; opening and closing each of the plurality of conduits in a controlled manner by an actuation mechanism having a piston positioned within a borehole structure surrounding the piston; maintaining a fluid tight seal between the piston and the bore structure during the opening and closing, wherein the piston and the bore structure have close tolerances configured to produce the fluid tight seal, wherein the close tolerances produce a gap between the piston and the bore structure of less than 6 microns; mixing the plurality of solvents in a controlled manner within the manifold of the gradient proportioning valve; providing a continuous flow of a componentally accurate mixture of the plurality of solvents; outputting a continuous flow of the accurate mixture of the components from the common outlet port of the gradient proportioning valve to a pump; The piston is rotated about the drilling structure to open and close the at least one conduit of the plurality of conduits in the controlled manner.

13. The method according to claim 12, further comprising: Unwanted fluid pressure pulses in the manifold are prevented using the actuation mechanism by minimizing internal fluid volume within the piston and the drilling structure.

14. The method according to claim 12, wherein: The actuating mechanism is made of ceramic.

15. The method of claim 12, further comprising opening two or more of the plurality of conduits using the actuation mechanism.

16. The method of claim 12, further comprising axially moving the piston within the drilling structure to open and close the at least one conduit of the plurality of conduits in the controlled manner.

17. The method of claim 12, further comprising moving the piston both axially and rotationally relative to the drilling structure.

18. A liquid chromatography system, comprising: The gradient proportional valve according to claim 1; a pump located downstream of the gradient proportioning valve; Ejector; Separation column; as well as Detector.

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