Replaceable single-tube coriolis sensor assembly and its method of manufacturing

Abstract

A flowmeter (5) is provided. The flowmeter (5) comprises a disposable cassette (200) further comprising a first shell (202) and a flowtube (206) coupled to the first shell (202). A dock (300) comprises a base (302), a clamp portion (304) coupled to the base (302), and operable to move between a clamped position and an open position, and a bay (306) defined between the base and the clamp portion (304), wherein the cassette (200) is installable in the bay (306), and wherein the dock (300) is further operable to couple the installed cassette (200) thereto by actuating the clamp portion (304) into the clamped position.

Description

[0001] REPLACEABLE SINGLE-TUBE CORIOLIS SENSOR ASSMEBLY AND

[0002] RELATED METHOD

[0003] TECHNICAL FIELD

[0004] The present invention relates to flowmeters, and more particularly, to a flowmeter having a replaceable wetted component cassette.

[0005] BACKGROUND OF THE INVENTION

[0006] Vibrating sensors, such as for example, vibrating densitometers and Coriolis flowmeters are generally known, and are used to measure mass flow and other information related to materials flowing through a conduit in the flowmeter. Exemplary flowmeters are disclosed in U.S. Patent 4,109,524, U.S. Patent 4,491,025, and Re. 31,450, all to J.E. Smith et al. These flowmeters have one or more conduits of a straight or curved configuration. Each conduit configuration in a Coriolis mass flowmeter, for example, has a set of natural vibration modes, which may be of simple bending, torsional, or coupled type. Each conduit can be driven to oscillate at a preferred mode.

[0007] Some types of mass flowmeters, especially Coriolis flowmeters, are capable of being operated in a manner that performs a direct measurement of density to provide volumetric information through the quotient of mass over density. See, e.g., U.S. Pat. No. 4,872,351 to Ruesch for a net oil computer that uses a Coriolis flowmeter to measure the density of an unknown multiphase fluid. U.S. Pat. No. 5,687,100 to Buttler et al. teaches a Coriolis effect densitometer that corrects the density readings for mass flow rate effects in a mass flowmeter operating as a vibrating tube densitometer.

[0008] Material flows into the flowmeter from a connected pipeline on the inlet side of the flowmeter, is directed through the conduit(s), and exits the flowmeter through the outlet side of the flowmeter. The natural vibration modes of the vibrating system are defined in part by the combined mass of the conduits and the material flowing within the conduits.

[0009] When there is no flow through the flowmeter, a driving force applied to the conduit(s) causes all points along the conduit(s) to oscillate with identical phase or with a small “zero offset”, which is a time delay measured at zero flow. As material begins to flow through the flowmeter, Coriolis forces cause each point along the conduit(s) to have a different phase. For example, the phase at the inlet end of the flowmeter lags the phase at the centralized driver position, while the phase at the outlet leads the phase at the centralized driver position. Pickoffs on the conduit(s) produce sinusoidal signals representative of the motion of the conduit(s). Signals output from the pickoffs are processed to determine the time delay between the pickoffs. The time delay between the two or more pickoffs is proportional to the mass flow rate of material flowing through the conduit(s).

[0010] Meter electronics connected to the driver generate a drive signal to operate the driver and also to determine a mass flow rate and / or other properties of a process material from signals received from the pickoffs. The driver may comprise one of many well- known arrangements; however, a magnet and an opposing drive coil have received great success in the flowmeter industry. An alternating current is passed to the drive coil for vibrating the conduit(s) at a desired conduit amplitude and frequency. It is also known in the art to provide the pickoffs as a magnet and coil arrangement very similar to the driver arrangement. However, while the driver receives a cunent which induces a motion, the pickoffs can use the motion provided by the driver to induce a voltage. The magnitude of the time delay measured by the pickoffs is very small; often measured in nanoseconds. Therefore, it is necessary to have the transducer output be very accurate.

[0011] Generally, a flowmeter can be initially calibrated and a flow calibration factor along with a zero offset can be generated. In use, the flow calibration factor can be multiplied by the time delay measured by the pickoffs minus the zero offset to generate a mass flow rate. In most situations, the flowmeter is initially calibrated, typically by the manufacturer, and assumed to provide accurate measurements without subsequent calibrations required.

[0012] Vibrating sensors, including Coriolis flowmeters, are often employed in applications that subject the wetted components, such as conduits, for example, to process materials that are hazardous, toxic, or difficult to remove completely. This includes biological applications where safety, contamination, and biohazard issues are of paramount importance. In such applications, the wetted components are generally non- reusable. In cases where there is a need to measure flow for a destructive process material for only several days or a few weeks, such as in a filling or dispensing environment, the cost for a complete meter is too high, and therefore the use of such a meter may not be practical. The present invention overcomes these and other problems and an advance in the art is achieved.

[0013] A Coriolis flow meter is typically constructed with metal components forming the flow path for the process fluid. The process fluid is in direct contact with the interior surfaces of the tubes, manifolds and process connections. If the operator of the process intends to change fluids that can't intermix, thorough cleaning of the flow path is required, which can result in significant down time. According to embodiments, a temporary-use and easily changed flow path assembly formed as a rigid cassette is disclosed. Shells around the flowtube provide some mass, flowtube protection, and indexability, while the rigid construction of the cassette allows it to be coupled to the significantly larger mass of the reusable portion of the system, the cassette dock. The method of coupling additional system mass from the dock assembly is also disclosed. Coupling this mass to the cassette improves performance and allows for a lower mass cassette assembly. Once the cassette has been exposed to a process material, the cassette may be replaced with a new cassette, yet still utilize the original dock.

[0014] SUMMARY OF THE INVENTION

[0015] A flowmeter is provided according to an embodiment. The flowmeter comprises a disposable cassette comprising a first shell and a flowtube coupled to the first shell. The flowmeter comprises a dock comprising a base, a clamp portion coupled to the base, and operable to move between a clamped position and an open position, and a bay defined between the base and the clamp portion, wherein the cassette is installable in the bay, and wherein the dock is further operable to couple the installed cassette thereto by actuating the clamp portion into the clamped position.

[0016] A method of manufacturing a flowmeter is provided according to an embodiment. The method comprises forming a disposable cassette comprising a flowtube therein by forming a first shell and coupling the flowtube to the first shell. The method comprises forming a dock by providing a base, coupling a clamp portion to the base, the clamp portion operable to move between a clamped position and an open position, and defining a bay between the base and the clamp portion. The cassette is installed in the bay, and the clamp portion is actuated into the clamped position to couple the installed cassette to the dock. ASPECTS

[0017] According to an aspect, a flowmeter comprises a disposable cassette comprising a first shell and a flowtube coupled to the first shell. The flowmeter comprises a dock comprising a base, a clamp portion coupled to the base, and operable to move between a clamped position and an open position, and a bay defined between the base and the clamp portion, wherein the cassette is installable in the bay, and wherein the dock is further operable to couple the installed cassette thereto by actuating the clamp portion into the clamped position.

[0018] Preferably, the flowmeter comprises a second shell coupled to the first shell, wherein the flowtube is disposed between and coupled to both the first shell and the second shell.

[0019] Preferably, the cassette comprises a driver magnet coupled to the flowtubc and operable to vibrate the flowtube, a first pickoff magnet coupled to the flowtube and operable to vibrate in response to vibrations induced by the driver magnet, and a second pickoff magnet coupled to the flowtube and operable to vibrate in response to vibrations induced by the driver magnet.

[0020] Preferably, the dock comprises a driver coil in magnetic communication with the driver magnet, and operable to receive a vibratory signal and induce motion of the flowtube with the driver magnet, a first pickoff coil in magnetic communication with the first pickoff magnet, and operable to generate a vibratory signal induced by a motion of the first pickoff magnet, and a second pickoff coil in magnetic communication with the second pickoff magnet, and operable to generate a vibratory signal induced by a motion of the second pickoff magnet.

[0021] Preferably, the cassette comprises a first attachment region formed by at least one of the first and second shells, and a second attachment region formed by at least one of the first and second shells, wherein an inlet leg of the flowtube is coupled to the first attachment region, and an outlet leg of the flowtube is coupled to the second attachment region.

[0022] Preferably, the first attachment region and the second attachment region operate as brace bars for the flowtube. Preferably, at least one of the first and second shells comprises at least one rigidity feature.

[0023] Preferably, the base and clamp portion engage at least one of the rigidity features to clampedly couple the installed cassette to the base and clamp portion when in the clamped position.

[0024] Preferably, at least one of the first and second shells comprises at least one of a driver magnet through-hole, a first pickoff magnet through-hole, and a second pickoff magnet through-hole.

[0025] Preferably, the dock comprises a magnetic keeper disposed in the base, proximate the driver coil operable to engage one of the through-holes.

[0026] Preferably, the dock comprises a first magnetic keeper disposed in the base, proximate the driver coil, a second magnetic keeper disposed in the base, proximate the first pickoff coil, and a third magnetic keeper disposed in the base, proximate the second pickoff coil, wherein the first, second and third magnetic keepers at least partially protrude into the bay and are operable to engage the driver magnet through-hole, the first pickoff magnet through-hole, and the second pickoff magnet through-hole, respectively, to index the cassette in the bay.

[0027] Preferably, the first shell and the second shell are formed from sheet metal.

[0028] Preferably, the first shell and the second shell are coupled with at least one of brazing or adhering.

[0029] Preferably, the dock comprises a mass that is greater than the mass of the cassette.

[0030] According to an aspect, a method of manufacturing a flowmeter comprises forming a disposable cassette comprising a flowtube therein by forming a first shell and coupling the flowtube to the first shell. The method comprises forming a dock by providing a base, coupling a clamp portion to the base, the clamp portion operable to move between a clamped position and an open position, and defining a bay between the base and the clamp portion. The cassette is installed in the bay, and the clamp portion is actuated into the clamped position to couple the installed cassette to the dock.

[0031] Preferably, the method comprises forming a second shell, placing the flowtube between the first shell and the second shell, and coupling the flowtube to the second shell and coupling the first shell to the second shell. Preferably, the method comprises coupling a driver magnet to the flowtube, the driver magnet operable to vibrate the flowtube, coupling a first pickoff magnet to the flowtube, the first pickoff magnet operable to vibrate in response to vibrations induced by the driver magnet, and coupling a second pickoff magnet to the flowtube, the second pickoff magnet operable to vibrate in response to vibrations induced by the driver magnet.

[0032] Preferably, the method comprises installing, in the dock, a driver coil in magnetic communication with the driver magnet, the driver coil operable to receive a vibratory signal and induce motion of the flowtube with the driver magnet, installing, in the dock, a first pickoff coil in magnetic communication with the first pickoff magnet, the first pickoff coil operable to generate a vibratory signal induced by the motion of the first pickoff magnet, and installing, in the dock, a second pickoff coil in magnetic communication with the second pickoff magnet, the second pickoff coil operable to generate a vibratory signal induced by the second pickoff magnet.

[0033] Preferably, the method comprises forming a first attachment region in at least one of the first and second shells, forming a second attachment region in at least one of the first and second shells, coupling an inlet leg of the flowtube to the first attachment region, and coupling an outlet leg of the flowtube to the second attachment region.

[0034] Preferably, the method comprises forming a brace bar with the first attachment region and the second attachment region.

[0035] Preferably, the method comprises forming at least one rigidity feature in at least one of the first and second shells, wherein the base and clamp portion are operable to engage at least one of the at least one rigidity feature to clampedly couple the installed cassette to the base and clamp portion when in the clamped position.

[0036] Preferably, the method comprises forming, in at least one of the first and second shells, a driver magnet through-hole, forming, in at least one of the first and second shells, a first pickoff magnet through-hole, and forming, in at least one of the first and second shells, a second pickoff magnet through-hole.

[0037] Preferably, the method comprises installing a first magnetic keeper in the base, proximate the driver coil, installing a second magnetic keeper in the base, proximate the first pickoff coil, and installing a third magnetic keeper in the base, proximate the second pickoff coil, wherein the first, second and third magnetic keepers at least partially protrude into the bay and are operable to engage the driver magnet through-hole, the first pickoff magnet through-hole, and the second pickoff magnet through-hole, respectively, and operable to index the cassette in the bay.

[0038] Preferably, the method comprises forming the first shell and the second shell from sheet metal.

[0039] Preferably, the method comprises brazing the first shell to the second shell.

[0040] Preferably, the dock comprises a mass that is greater than the mass of the cassette.

[0041] BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG. 1 illustrates a prior art sensor assembly;

[0043] FIG. 2 illustrates a prior art sensor assembly having a case;

[0044] FIG. 3 illustrates a cassette according to an embodiment;

[0045] FIG. 4 illustrates a cutaway view of the cassette of FIG. 3;

[0046] FIG. 5 illustrates an exploded view of the cassette of FIGS. 3 and 4;

[0047] FIG. 6A illustrates a dock in the unclamped position;

[0048] FIG. 6B illustrates the dock of FIG. 6A in the clamped position;

[0049] FIG. 7 illustrates a section view of the dock of FIGS. 6A and 6B.

[0050] DETAILED DESCRIPTION OF THE INVENTION

[0051] FIGS. 1-7 and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents.

[0052] FIG. 1 illustrates a prior art flowmeter 5, which can be any vibrating meter, such as a Coriolis flowmeter or densitometer, for example without limitation. The flowmeter 5 comprises a sensor assembly 10 and meter electronics 20. The sensor assembly 10 responds to mass flow rate and density of a process material. Meter electronics 20 are connected to the sensor assembly 10 via leads 100 to provide density, mass flow rate, and temperature information over path 26, as well as other information. The sensor assembly 10 includes flanges 101 and 10T, a pair of manifolds 102 and 102', a pair of parallel conduits 103 (first conduit) and 103’ (second conduit), a driver 104, a temperature sensor 106 such as a resistive temperature detector (RTD), and a pair of pickoffs 105 and 105', such as magnet / coil pickoffs, strain gages, optical sensors, or any other pickoff known in the art. The conduits 103 and 103’ have inlet legs 107 and 107' and outlet legs 108 and 108', respectively. Conduits 103 and 103’ bend in at least one symmetrical location along their length and are essentially parallel throughout their length. Each conduit 103, 103’, oscillates about axes W and W', respectively.

[0053] The legs 107, 107', 108, 108' of conduits 103,103’ are fixedly attached to conduit mounting blocks 109 and 109' and these blocks, in turn, are fixedly attached to manifolds 102 and 102'. This provides a continuous closed material path through the sensor assembly 10.

[0054] When flanges 101 and 10T are connected to a process line (not shown) that carries the process material that is being measured, material enters a first end 110 of the flowmeter 5 through a first orifice (not visible in the view of FIG. 1) in flange 101 , and is conducted through the manifold 102 to conduit mounting block 109. Within the manifold 102, the material is divided and routed through conduits 103 and 103’. Upon exiting conduits 103 and 103’, the process material is recombined in a single stream within manifold 102' and is thereafter routed to exit a second end 112 connected by flange 101' to the process line (not shown).

[0055] Conduits 103 and 103’ are selected and appropriately mounted to the conduit mounting blocks 109 and 109' so as to have substantially the same mass distribution, moments of inertia, and Young's modulus about bending axes W— W and W'— W, respectively. Inasmuch as the Young's modulus of the conduits 103, 103’ changes with temperature, and this change affects the calculation of flow and density, a temperature sensor 106 is mounted to at least one conduit 103, 103’ to continuously measure the temperature of the conduit. The temperature of the conduit, and hence the voltage appealing across the temperature sensor 106 for a given current passing therethrough, is governed primarily by the temperature of the material passing through the conduit. The temperature-dependent voltage appearing across the temperature sensor 106 is used in a well-known method by meter electronics 20 to compensate for the change in elastic modulus of conduits 103, 103' due to any changes in conduit 103, 103' temperature. The temperature sensor is connected to meter electronics 20.

[0056] Both conduits 103,103’ are driven by driver 104 in opposite directions about their respective bending axes W and W' at what is termed the first out-of-phase bending mode of the flowmeter. This driver 104 may comprise any one of many well-known arrangements, such as a magnet mounted to conduit 103’ and an opposing coil mounted to conduit 103, through which an alternating current is passed for vibrating both conduits. A suitable drive signal is applied by meter electronics 20, via lead 113, to the driver 104. It should be appreciated that while the discussion is directed towards two conduits 103, 103", in other embodiments, only a single conduit may be provided or more than two conduits may be provided. It is also within the scope of the present invention to produce multiple drive signals for multiple drivers.

[0057] Meter electronics 20 receive the temperature signal on lead 114, and the left and right velocity signals appearing on leads 115 and 115’, respectively. Meter electronics 20 produce the drive signal appearing on lead 113 to driver 104 and vibrate conduits 103, 103’. Meter electronics 20 process the left and right velocity signals and the temperature signal to compute the mass flow rate and the density of the material passing through the sensor assembly 10. This information, along with other information, is applied by meter electronics 20 over path 26 to utilization means. An explanation of the circuitry of the meter electronics 20 is not needed to understand the present invention and is omitted for brevity of this description. It should be appreciated that the description of FIG. 1 is provided merely as an example of the operation of one possible vibrating meter and is not intended to limit the teaching of the present invention.

[0058] FIG. 2 illustrates an embodiment of a prior art sensor assembly 10 that is encased by a case 120. Much of the sensor assembly 10 is hidden from view by the case 120, but the manifolds 102, 102’, and flanges 101, 101' are visible. In this embodiment, adapters 203, 203’ are welded to connect the flanges 101, 101’ to their respective manifolds 102, 102'. A process line (not shown) may be connected to the flanges 101, 101’ for typical use.

[0059] FIG. 3-5 illustrate a cassette 200 according to an embodiment. The cassette 200 is the disposable portion of the flowmeter 5, and the wetted portion of the flowmeter 5. The cassette 200 is removably installable into a dock 300. The cassette 200 contains a flowtube 206 through which process fluid flows. A first shell 202 and second shell 204 house the flowtube 206 therebetween.

[0060] In embodiments, the first shell 202 and second shell 204 are made from sheet metal, and the first and second shells 202, 204 are brazed together, with the flowtube attached to each of the first and second shells 202, 204, also by brazing. In embodiments, the first shell 202 and second shell 204 are made from other materials such as plastics, glass, composites, polymers, 3D printed and additive manufacturing materials, etc., and the first and second shells 202, 204 are bonded together, with the flowtube 206 bonded to each of the first and second shells 202, 204. Flowtubes 206, in embodiments, are made from the same material as the shell. Having the same materials for flowtubes 206 and shells 202, 204 promotes bonding compatibility and thermal expansion compatibility. In the embodiments provided, the construction and arrangement of the flowmeter 5 is not susceptible to deleterious thermal expansion-related effects. In embodiments, the flowtubes 206 are constructed from metals, such as stainless steel, Hastelloy, titanium, tantalum, zirconium, for example, and glass, plastic, polymers, 3D printed and additive manufacturing materials, composites, combinations thereof, and other materials known in the art. In embodiments, the flowtubes 206 are constructed from different materials than the shells 202, 204. For example, and without limitation, a glass flowtube 206 may be utilized with stainless steel shells 202, 204. Bonding may comprise welding, brazing, adhering, chemical joining, mechanically fastening, combinations thereof, and other attachment means known in the art.

[0061] The cassette 200 comprises a first attachment region 212 formed by at least one of the first and second shells 202, 204, and a second attachment region 214 formed by at least one of the first and second shells 202, 204. An inlet leg 216 of the flowtube 206 is coupled to the first attachment region 212, and the outlet leg 218 of the flowtube 206 is coupled to the second attachment region 214. In the embodiment illustrated, the attachment regions 212, 214, are semicircular portions of each shell 202, 204 having a mating diameter to that of the outer diameter of the flowtube 206. During assembly of the cassette, the flowtube 206 is sandwiched between the attachment regions 212, 214, and brazed thereto. In an embodiment, the area of the attachment regions 212, 214 are the only points of contact between the shells 202, 204 and the flowtube 206. This allows the flowtube 206 to vibrate without impediment. In some embodiments, this area acts as brace bars for the flowtube 206. By adjusting the size of the attachment regions 212, 214, and the location on the flowtube 206 that is brazed to the attachment regions 212, 214, the resonant frequency of the flowtube 206 is adjustable. This aids in separating the frequency at which the flowtube 206 is vibrated from vibrations that are imparted into the flowtube from process connections or pressure pulsations of the process fluid. In some embodiments, additional features in the shells 202, 204 that are inline with the attachment regions 212, 214 act as brace bars.

[0062] The inlet and outlet legs 216, 218 comprise attachment points where the flowtube 206 interfaces with process lines (not shown) that deliver a process fluid to be measured by the flowmeter 5. In an embodiment, the flowtube is connected to tubing using a clamp. In an embodiment, hardware fittings on the inlet and outlet legs 216, 218 interfaces with process lines. For example, swaged fittings, compressing fittings, push-to-connect fittings, threaded fittings, flare fittings, welded or brazed fittings, and union fittings arc considered, as are other means of connecting tubes and pipes at a joint that are known in the art.

[0063] The flowtube 206 has a driver magnet 208, a first pickoff magnet 210A, and a second pickoff magnet 210B coupled thereto. The magnets 208, 210A, 210B are attached to the flowtube 206 either directly or indirectly via mounts 309. In embodiments, the mounts 309 are brazed to the flowtube 206, and the magnets 208, 210A, 210B are coupled to the mounts 309. The first shell 202 has corresponding holes that match the magnets’ 208, 210A, 210B locations. A driver magnet through-hole 222 is proximate the driver magnet 208. A first pickoff magnet through-hole 224 and second pickoff magnet through- hole 226 are proximate the first pickoff magnet 210A and a second pickoff magnet 210B, respectively. In an embodiment, the through-holes 222, 224, 226 are larger diameter than the magnets 208, 210A, 210B. In an embodiment, the through-holes 222, 224, 226, and magnets 208, 210A, 210B are, respectively, non-coplanar concentric to each other. In embodiments, the flowtube is positioned between the shells 202, 204 for brazing, and the flowtube 206 is indexed in position using at least one of the through-holes 222, 224, 226.

[0064] Rigidity features 220 are formed in at least one of the shells 202, 204. In an embodiment, forming the rigidity features 220 involves pressing sheet metal. In the embodiments illustrated, the rigidity features 220 are formed in both of the shells 202, 204, and are symmetrical, both within each shell 202, 204 and between each shell 202, 204. In embodiments, the rigidity features 220 are formed in both of the shells 202, 204, and are asymmetrical within each shell 202, 204. In embodiments, the rigidity features 220 are formed in both of the shells 202, 204, and are asymmetrical between each shell 202, 204. The rigidity features 220 allow clearance for the flowtube 206 to vibrate without unwanted contact with the shells 202, 204, strengthen the cassette 200, and provide a surface for coupling with the dock 300. At least one rigidity feature 220 is formed with a planar surface 221 that provides the contact points between the shells 202, 204 and the dock 300. It should be noted that only one shell 202, 204 has rigidity features in embodiments.

[0065] In embodiments, a single shell is used to secure the tube and provide rigidity and coupling to the dock. In an embodiment, rigidity features 220 are formed on a single shell 202 such that contact points lie both above and below the flowtube 206. In this manner, the flowtubc 206 is not wholly encased by the shell 202, but the rigidity features contact both the base 302 and the clamp portion 304 of the dock 300, thus allowing clearance for the flowtube 206 to vibrate. In an embodiment, features (not shown) protruding from the surface of the base 302 and / or the clamp portion 304 engage the shell 202. In embodiments, these features are provided in conjunction with rigidity features 220 formed on the single shell 202 that have contact points which lie both above and below the flowtube 206. In embodiments, the features that protrude from the surface of the base 302 and / or the clamp portion 304 to engage the shell 202 provide points of contact between the dock 300 and the single shell 202, such that a secure attachment is effectuated and clearance for the flowtube 206 to vibrate when the single shell 202 is docked in the bay 306 is provided. In an embodiment of such a configuration, the flowtube 206 is protected by the shell 202 on one side, while the opposing side is “open faced.” In another embodiment, a removable adapter that emulates features that protrude from the surface of the base 302 and / or the clamp portion 304 is provided. Therefore, the base 302 and / or the clamp portion 304 are flat or mostly flat, such that a double- shelled cassette 200 embodiment is dockable, as described herein, yet single shell 202 embodiments, in conjunction with the adapter, are also dockable in the same dock 300 unit.

[0066] The dock 300 is the non-disposable portion of the flowmeter 5, and contains a bay 306 in which the cassette 200 can be docked. The dock 300 contains meter electronics, transducer portions, wiring, temperature and other sensors, and one or more docking mechanisms. The dock 300 is made up of two primary portions, the base 302, and the clamp portion 304. The clamp portion 304 is actuatable to open the bay 306 so that the cassette 200 may be docked and undocked in the bay 306. When the clamp portion 304 is in a clamped position, the docked cassette 200 is clamped into place. The clamp portion 304 has a planar region 305 A, and the base 302 has one or more planar regions 305B. The planar regions 305A, 305B mate with the planar surface 221 of the rigidity feature(s), and clamping forces are applied to the mated surfaces to dock the cassette 200. The mass of the dock 300 is higher than that of the cassette. In embodiments, the dock 300 is at least one order of magnitude greater in mass than the cassette 200. In embodiments, the dock 300 is at least two orders of magnitude greater in mass than the cassette 200. The clamp portion 304 provides the requisite clamping force to couple the cassette 200 to the dock 300, which will differ between meters, depending on the size, mass, and dimensions, rigidity feature 220 configuration, etc. It is the large mass of the dock 300 relative to the low mass cassette that allows the flowmeter 5 to accurately operate.

[0067] A driver coil 308, a first pickoff coil 310A, and a second pickoff coil 310B are imbedded in the base 302, and their positioning is non-coplanar concentric to the magnets 208, 210A, 210B, respectively when the cassette 200 is installed in the dock 300. The driver coil 308 is in magnetic communication with the driver magnet 208 and operable to receive vibratory signals from meter electronics 20, which induces a vibratory motion of the flowtube 206 via the driver magnet 208. The first pickoff coil 310A is in magnetic communication with the first pickoff magnet 210A and generates a vibratory signal induced by the motion of the first pickoff magnet 210A. The second pickoff coil 310B is in magnetic communication with the second pickoff magnet 210B and generates a vibratory signal induced by a motion of the second pickoff magnet 210B. The first and second pickoff magnets 210A, 210B, are induced to vibrate by the driver coil 308 driving the driver magnet 208 to vibrate the flowtube 206. The operating principles of the meter electronics 20, and the flowmeter 5 are the same or similar to that described above for prior art flowmeters. In general, an alternating current is passed through the driver coil 308, which creates a magnetic field that interacts with the driver magnet 208, which in turn vibrates the flowtube 206. A suitable drive signal is applied by meter electronics 20. Similarly, the vibratory motion of the pickoff magnets 210A, 210B induces a current in each pickoff coil 310A, 310B. Signals from each pickoff coil 310A, 310B are sent to meter electronics 20.

[0068] In an embodiment, the base 302 has one or more magnetic keepers 314, 316, 318 disposed in the base. The keepers 314, 316, 318 serve to provide low reluctance paths for magnetic fields to form completed magnetic circuits. This serves to concentrate and strengthen the magnetic fields of the magnets 208, 210A, 210B proximate respective coils 308, 310A, 310B, which fosters transducer efficiency. A first magnetic keeper 314 disposed in the base 302, proximate the driver coil 308, a second magnetic keeper 316 disposed in the base 302, proximate the first pickoff coil 310A, and a third magnetic keeper 318 disposed in the base 302, proximate the second pickoff coil 310B. The first, second and third magnetic keepers 314, 316, 318 are either concentric or non-coplanar concentric to the driver, first pickoff, and second pickoff coils 308, 310A, 310B, respectively. In an embodiment, the first, second and third magnetic keepers 314, 316, 318 are either not concentric or non-coplanar concentric to the driver, first pickoff, and second pickoff coils 308, 310A, 310B, respectively. In an embodiment, the magnetic keepers 314, 316, 318 protrude outward from a planar region 305B of the base. By protruding outwardly from the planar region 305, the magnetic keepers 314, 316, 318 are engageable with the through-holes 222, 224, 226. This configuration locates the cassette 200 relative to the coils 308, 310A, 310B and ensures that the coils 308, 310A, 310B, and magnets 208, 210A, 210B are in axial alignment.

[0069] The keepers 314, 316, 318 are bonded or pressed into the top plate and, in an embodiment, the coils 308, 310A, 310B are then bonded into the keepers 314, 316, 318. The assembly is fluid-tight in this area, so that process fluid cannot contact any electrical or electronic portions of the flowmeter 5.

[0070] In the embodiment illustrated, a lever 320 actuates the clamp portion 304 to move between unclamped (FIG. 6A) and clamped (FIG. 6B) positions. In an embodiment, a cam, such as a roller-bearing cam, provides the mechanism to impart forces that actuate the clamp portion 304. In such a case, the lever 320 action is coupled to a camming device that, when turned, acts directly or indirectly on the clamp portion 304. In an embodiment, springs 322 coupled to the clamp portion 304 provide an oppositional force that is overcome by the lever-mediated actuation for clamping, yet aids in the release of the clamp portion to an unclamped position when the lever 320 is placed in an unclamped position. In other embodiments, powered actuators, such as pneumatic cylinders, hydraulic cylinders, linear- actuators, stepper motors, combinations thereof, and other means of actuation known in the art. In embodiments, springs 322 provide oppositional forces for powered embodiments.

[0071] In an embodiment, the system includes a user interface (UI) element. The UI element includes at least one of a display, touch screen, keypad, keyboard, buttons, and other UI elements known in the art. In an embodiment, meter electronics 5 and / or UI elements are integrated in the dock 300. In an embodiment, meter electronics 5 and / or UI elements are remote from the dock 300. In an embodiment, one of meter electronics 20 and the UI elements are remote from the dock 300, while one of meter electronics 20 and the UI elements are integrated in the dock 300. Communication is established between meter electronics 20 and electronic elements housed in the dock 300, such as coils 308, 310A, 310B and temperature sensors.

[0072] No fluids ever come in contact with the dock 300. The cassette 200 is the entirety of the “wet” portion of the flowmeter 5, and thus hazardous, corrosive, and / or toxic fluids may be measured without affecting the significantly more expensive dock 300, which is the “dry” portion of the flowmeter 5. Therefore, components of the dock that are sensitive to moisture or other caustic fluid characteristics are not at risk for fluid-mediated damage. Depending on the application, by replacing the disposable cassette 200 with a new cassette 200, this can avoid cross-contamination between differing fluids; avoid adverse reactions between incompatible fluids; avoid cross-contamination of patient samples; avoid excess corrosion; allows for easy disposal of biohazardous waste; allows for easy disposal of damaged or corroded flowtubes; and eliminates the need for cleaning the flowmeter 5.

[0073] It should be noted that the description and figures illustrate a single conduit system, but this is not limiting, as flowmeter 5 with more than one conduit are also considered. In an embodiment of a dual conduit flowmeter 5, two flowtubes are housed in a cassette. Variations of the dock that would place the coils roughly between the conduits are considered, as are variations where an additional set of coils is housed in the clamp portion. In the latter embodiment, magnets on each flowtube are oriented in magnetic opposition. Furthermore, a Coriolis flowmeter structure is described although it will be apparent to those skilled in the art that the present invention could be practiced on a vibrating tube densitometer or viscometer without the additional measurement capability provided by a Coriolis mass flowmeter.

[0074] The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated by the inventors to be within the scope of the invention. Indeed, persons skilled in the art will recognize that certain elements of the above-described embodiments may variously be combined or eliminated to create further embodiments, and such further embodiments fall within the scope and teachings of the invention. It will also be apparent to those of ordinary skill in the art that the abovedescribed embodiments may be combined in whole or in part to create additional embodiments within the scope and teachings of the invention.

[0075] Thus, although specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. The teachings provided herein can be applied to other flowmeter systems, and not just to the embodiments described above and shown in the accompanying figures. Accordingly, the scope of the invention should be determined from the following claims.

Claims

We Claim:

1. A flowmeter (5), comprising: a disposable cassette (200) comprising: a first shell (202); a flowtube (206) coupled to the first shell (202); and a dock (300) comprising: a base (302); a clamp portion (304) coupled to the base (302), and operable to move between a clamped position and an open position; and a bay (306) defined between the base and the clamp portion (304), wherein the cassette (200) is installable in the bay (306), and wherein the dock (300) is further operable to couple the installed cassette (200) thereto by actuating the clamp portion (304) into the clamped position.

2. The flowmeter (5) of claim 1, comprising a second shell (204) coupled to the first shell (202), wherein the flowtube (206) is disposed between and coupled to both the first shell (202) and the second shell (204).

3. The flowmeter (5) of claim 1, wherein the cassette (200) comprises: a driver magnet (208) coupled to the flowtube (206) and operable to vibrate the flowtube (206); a first pickoff magnet (210 A) coupled to the flowtube (206) and operable to vibrate in response to vibrations induced by the driver magnet (208); and a second pickoff magnet (210B) coupled to the flowtube (206) and operable to vibrate in response to vibrations induced by the driver magnet (208).

4. The flowmeter (5) of claim 3, wherein the dock (300) comprises: a driver coil (308) in magnetic communication with the driver magnet (208), and operable to receive a vibratory signal and induce motion of the flowtube (206) with thea first pickoff coil (310A) in magnetic communication with the first pickoff magnet (210A), and operable to generate a vibratory signal induced by a motion of the first pickoff magnet (210A); and a second pickoff coil (31 OB) in magnetic communication with the second pickoff magnet (210B), and operable to generate a vibratory signal induced by a motion of the second pickoff magnet (210B).

5. The flowmeter (5) of claim 2, wherein the cassette (200) comprises a first attachment region (212) formed by at least one of the first and second shells (202, 204), and a second attachment region (214) formed by at least one of the first and second shells (202, 204), wherein an inlet leg (216) of the flowtube (206) is coupled to the first attachment region (212), and an outlet leg (218) of the flowtube (206) is coupled to the second attachment region (214).

6. The flowmeter (5) of claim 5, wherein the first attachment region (212) and the second attachment region (214) operate as brace bars for the flowtube (206).

7. The flowmeter (5) of claim 2, wherein at least one of the first and second shells (202, 204) comprises at least one rigidity feature (220).

8. The flowmeter (5) of claim 7, wherein the base (302) and clamp portion (304) engage at least one of the rigidity features (220) to clampedly couple the installed cassette (200) to the base (302) and clamp portion (304) when in the clamped position.

9. The flowmeter (5) of claim 2, wherein at least one of the first and second shells (202, 204) comprises at least one of: a driver magnet through-hole (222); a first pickoff magnet through-hole (224); and a second pickoff magnet through-hole (226).

10. The flowmeter (5) of claim 9, wherein the dock (300) comprises: a magnetic keeper (314, 316, 318) disposed in the base (302), proximate the driver coil (308) operable to engage one of the through-holes (222, 224, 226).

11. The flowmeter (5) of claim 9, wherein the dock (300) comprises: a first magnetic keeper (314) disposed in the base (302), proximate the driver coil (308); a second magnetic keeper (316) disposed in the base (302), proximate the first pickoff coil (310A); a third magnetic keeper (318) disposed in the base (302), proximate the second pickoff coil (310B), wherein the first, second and third magnetic keepers (314, 316, 318) at least partially protrude into the bay (306) and are operable to engage the driver magnet through-hole (222), the first pickoff magnet through-hole (224), and the second pickoff magnet through-hole (226), respectively, to index the cassette (200) in the bay (306).

12. The flowmeter (5) of claim 2, wherein the first shell (202) and the second shell (204) are formed from sheet metal.

13. The flowmeter (5) of claim 2, wherein the first shell (202) and the second shell (204) are coupled with at least one of brazing or adhering.

14. The flowmeter (5) of claim 1, wherein the dock (300) comprises a mass that is greater than the mass of the cassette (200).

15. A method of manufacturing a flowmeter, comprising: forming a disposable cassette comprising a flowtube therein by: forming a first shell; coupling the flowtube to the first shell; and forming a dock by: providing a base;coupling a clamp portion to the base, the clamp portion operable to move between a clamped position and an open position; and defining a bay between the base and the clamp portion; and installing the cassette in the bay; actuating the clamp portion into the clamped position to couple the installed cassette to the dock.

16. The method of claim 14, comprising: forming a second shell; placing the flowtube between the first shell and the second shell; and coupling the flowtube to the second shell and coupling the first shell to the second shell.

17. The method of claim 14, comprising: coupling a driver magnet to the flowtube, the driver magnet operable to vibrate the flowtube; coupling a first pickoff magnet to the flowtube, the first pickoff magnet operable to vibrate in response to vibrations induced by the driver magnet; and coupling a second pickoff magnet to the flowtube, the second pickoff magnet operable to vibrate in response to vibrations induced by the driver magnet.

18. The method of claim 17, comprising: installing, in the dock, a driver coil in magnetic communication with the driver magnet, the driver coil operable to receive a vibratory signal and induce motion of the flowtube with the driver magnet; installing, in the dock, a first pickoff coil in magnetic communication with the first pickoff magnet, the first pickoff coil operable to generate a vibratory signal induced by the motion of the first pickoff magnet; and installing, in the dock, a second pickoff coil in magnetic communication with the second pickoff magnet, the second pickoff coil operable to generate a vibratory signal induced by the second pickoff magnet.

19. The method of claim 16, comprising: forming a first attachment region in at least one of the first and second shells; forming a second attachment region in at least one of the first and second shells; coupling an inlet leg of the flowtube to the first attachment region; and coupling an outlet leg of the flowtube to the second attachment region.

20. The method of claim 19, comprising forming a brace bar with the first attachment region and the second attachment region.

21. The method of claim 16, comprising forming at least one rigidity feature in at least one of the first and second shells, wherein the base and clamp portion are operable to engage at least one of the at least one rigidity feature to clampedly couple the installed cassette to the base and clamp portion when in the clamped position.

22. The method of claim 16, comprising: forming, in at least one of the first and second shells, a driver magnet through- hole; forming, in at least one of the first and second shells, a first pickoff magnet through -hole; and forming, in at least one of the first and second shells, a second pickoff magnet through-hole.

23. The method of claim 22, comprising: installing a first magnetic keeper in the base, proximate the driver coil; installing a second magnetic keeper in the base, proximate the first pickoff coil; installing a third magnetic keeper in the base, proximate the second pickoff coil, wherein the first, second and third magnetic keepers at least partially protrude into the bay and are operable to engage the driver magnet through-hole, the first pickoff magnet through-hole, and the second pickoff magnet through-hole, respectively, and operable to index the cassette in the bay.

24. The method of claim 16, comprising forming the first shell and the second shell from sheet metal.

25. The method of claim 16, comprising brazing the first shell to the second shell.

26. The method of claim 14, wherein the dock comprises a mass that is greater than the mass of the cassette.

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