# US 2008/0184816 A1 · Vibration-type measurement transducer with improved measurement accuracy > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0184816 A1 - Document ID: US20080184816A1 - Status: Published application - Kind: A1 - Application number: 12/078,376 - Filed: 2008-03-31 - Published: 2008-08-07 - Earliest claimed: 2004-12-13 - Assignees: Endress + Hauser Flowtec AG - Inventors: Martin Anklin-Imhof; Christian Schuetze - Web page: https://patentgrep.com/patent/US20080184816A1 ## CPC - G01F 1/8409: {constructional details} - G01F 1/8413: {means for influencing the flowmeter's motional or vibrational behaviour, e.g., conduit support or fixing means, or conduit attachments} - G01F 1/8477: {with multiple measuring conduits} - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME ## Abstract The measurement transducer includes a transducer housing, which exhibits a plurality of natural oscillation modes, as well as at least one first flow tube held oscillatably in the transducer housing, vibrating at least at times, and conveying at least a portion of the medium to be measured. Additionally, the measurement transducer includes an electromechanical, especially electrodynamic, exciter arrangement acting on the at least one flow tube for producing and/or maintaining mechanical oscillations of the at least one flow tube, and a sensor arrangement reacting to movements of the flow tube, especially bending oscillations, for producing at least one oscillation measurement signal representing oscillations of the flow tube. Additionally, for improving the oscillation properties and, consequently, also the measurement accuracy of the measurement transducer, at least three coupling elements are provided for connecting the first and second flow tubes together at the inlet end, as well as at least three coupling elements for connecting the first and second flow tubes together at the outlet end. By using at least six coupling elements, it is possible to produce vibration-type measurement transducers of high measuring accuracy even at large nominal diameters of more than 150 mm, especially also while largely maintaining already established and proven forms of construction. ## Claims ### Claim 1 A measurement transducer of vibration-type for measuring a flowable medium, especially a gas, liquid, powder or other flowable substance, conveyed in a pipeline, said measurement transducer comprising: a transducer housing, which is mechanically coupled with the pipeline via an inlet end and an outlet end; at least one first flow tube held in an oscillatable manner in said transducer housing and vibrating at least at times, and a second flow tube mechanically coupled with said at least one first flow tube and likewise vibrating at least at times; an electromechanical, especially electrodynamic, exciter arrangement acting on at least one of the flow tubes for producing and/or maintaining mechanical oscillations of the at least one flow tube; a sensor arrangement reacting to movements at least of said at least one first flow tube, especially to bending oscillations, for producing at least one oscillation measurement signal representing oscillations of said at least one first flow tube; and at least three coupling elements connecting the first and the second flow tubes together at their inlet ends, as well as at least three coupling elements connecting the first and the second flow tubes together at their outlet ends, wherein: the first flow tube and said second flow tube execute during operation, at least at times, bending oscillations each about an imaginary oscillation axis essentially parallel to a longitudinal axis of the measurement transducer, and at least said at least one first flow tube is embodied as a first measuring tube communicating with the pipeline and serving to convey the medium to be measured; ### Claim 2 (depends on 1) The measurement transducer as claimed in claim 1, wherein: two flow tubes oscillate during operation essentially with opposite phase. ### Claim 3 (depends on 1) The measurement transducer as claimed in claim 1, wherein each of the two flow tubes has an at least sectionally curved central, middle tube segment. ### Claim 4 (depends on 3) The measurement transducer as claimed in claim 3, wherein the inlet-end coupling elements and the outlet-end coupling elements are so arranged and fixed on the two flow tubes that those clamping forces produced by the vibrating flow tubes within the transducer housing are minimized, which act predominantly in the direction of that principal axis of inertia of the measurement transducer, that runs essentially perpendicularly to the longitudinal axis and that lies essentially in an imaginary central plane of the measurement transducer extending between the two curved middle tube segments of the flow tubes; and/or wherein each of the two flow tubes has at an inlet end a straight inlet tube segment extending essentially parallel to the imaginary oscillation axis, each inlet tube segment communicates with its middle tube segment via an inlet-end, curved, intermediate tube segment and wherein each of the two flow tubes has at an outlet end a straight outlet tube segment extending essentially parallel to the imaginary oscillation axis and each outlet tube segment communicates with its middle tube segment via an outlet-end, curved, intermediate tube segment. ### Claim 5 (depends on 4) The measurement transducer as claimed in claim 4, wherein at least one first and at least one second coupling element of the coupling elements, connecting the two flow tubes on the inlet end with one another, are each affixed to the inlet-end, intermediate tube segments of the first and second flow tubes, and wherein at least one first and at least one second coupling element of the coupling elements, connecting the two flow tubes on the outlet end with one another, are each affixed to the outlet-end, intermediate tube segments of the first and second flow tubes. ### Claim 6 (depends on 4) The measurement transducer as claimed in claim 4, wherein at least one, third coupling element of the coupling elements connecting the two flow tubes together on the inlet end is fixed to each of the inlet-end tube segments of the first and second flow tubes and wherein at least one, third coupling element of the coupling elements connecting the two flow tubes together on the outlet end is fixed to each of the outlet-end tube segments of the first and second flow tubes. ### Claim 7 (depends on 3) The measurement transducer as claimed in claim 3, wherein each of the middle tube segments of the two flow tubes has an essentially V-shape and wherein each of the middle tube segments of the two flow tubes has an apex with an included apex angle smaller than 150°, especially smaller than 120°. ### Claim 8 (depends on 1) The measurement transducer as claimed in claim 1, wherein the first flow tube runs essentially parallel to the second flow tube; and/or wherein the first measurement transducer tube is essentially constructed identically to the second measurement transducer tube. ### Claim 9 (depends on 1) The measurement transducer as claimed in claim 1, further comprising a first distributor piece connecting the first and second flow tubes together at the inlet end, as well as a second distributor piece connecting the first and second flow tubes together at the outlet end, wherein the second flow tube likewise is constructed as a second measuring tube serving for the conveying of the medium to be measured and for communicating with the pipeline. ### Claim 10 (depends on 1) The measurement transducer as claimed in claim 1, wherein each of the two distributor pieces has a mass of more than 10 kg, especially more than 20 kg. ### Claim 11 (depends on 10) The measurement transducer as claimed in claim 10, wherein an external oscillation system of the measurement transducer is formed by the transducer housing and at least by the distributor pieces, while an internal oscillation system of the measurement transducer is formed by the two flow tubes, the medium at least instantaneously conveyed therein and at least in part by the exciter and sensor arrangements, and wherein the internal oscillation system, driven by the exciter arrangement, executes during operation of the measurement transducer, at least at times, mechanical oscillations, especially in the form of lateral oscillations, having at least one wanted oscillation frequency, which depends both on the size, shape and material of the flow tube and on an instantaneous density of the medium, and which is changeable during operation of the measurement transducer within a predetermined wanted frequency band having lower and upper limit frequencies. ### Claim 12 (depends on 1) The measurement transducer as claimed in claim 1, wherein a total mass of the external oscillation system amounts to at least 200 kg, especially more than 300 kg. ### Claim 13 (depends on 12) The measurement transducer as claimed in claim 12, wherein a mass ratio of a total mass of the external oscillation system to a total mass of the internal oscillation system is, during operation, at least at times, smaller than 3, especially smaller than 2.5. ### Claim 14 (depends on 12) The measurement transducer as claimed in claim 12, wherein a mass ratio of the total mass of the external oscillation system to the total mass of the internal oscillation system is continuously smaller than 3. ### Claim 15 (depends on 1) The measurement transducer as claimed in claim 1, wherein the transducer housing includes a support element, especially one of steel, with which the at least one flow tube is mechanically connected at its inlet and outlet ends. ### Claim 16 (depends on 1) The measurement transducer as claimed in claim 1, wherein the support element is constructed in the form of a support cylinder, especially a tubular support cylinder, which is at least partially laterally open and connected with the at least one flow tube such that the at least one, curved tube segment protrudes laterally out of the support cylinder. ### Claim 17 (depends on 1) The measurement transducer as claimed in claim 1, wherein the support element has a mass of at least 70 kg, especially more than 140 kg, and/or a length of at least 1000 mm, especially of more than 1200 mm. ### Claim 18 (depends on 1) The measurement transducer as claimed in claim 1, wherein each of the flow tubes and the transducer housing, is made, at least in part, of steel, especially stainless steel. ### Claim 19 (depends on 1) The measurement transducer as claimed in claim 1, wherein each of the flow tubes shows at least one of the following technical features: a mass of at least 10 kg, especially of greater than 25 kg, an inner diameter of at least 80 mm, especially greater than 100 mm, a cross section whose area moment of inertia is greater than 2×104 mm3, especially greater than 4×106 mm4, a cross section whose section modulus resisting bending is greater than 106 mm4, especially greater than 2×106 mm4, and a stretched length of at least 1000 mm, especially greater than 1500 mm. ### Claim 20 (depends on 1) The measurement transducer as claimed in claim 1, wherein an internal oscillation system of the measurement transducer is formed by the two flow tubes, the medium at least instantaneously conveyed therein, and at least in part by the exciter and sensor arrangements, and wherein the internal oscillation system, driven by the exciter arrangement, executes during operation of the measurement transducer, at least at times, mechanical oscillations, especially in the form of lateral oscillations, with at least one wanted oscillation frequency, which depends both on the size, shape and material of the flow tube and on an instantaneous density of the medium, and which is changeable during operation of the measurement transducer, within a predetermined wanted frequency band having upper and lower limit frequencies. ### Claim 21 (depends on 1) The measurement transducer as claimed in claim 1, wherein a total mass of the internal oscillation system amounts to at least 70 kg, and especially during operation, at least at times, to more than 90 kg. ### Claim 22 (depends on 1) The measurement transducer as claimed in claim 1, wherein an installed mass to nominal diameter ratio of an installed mass of the total measurement transducer to a nominal diameter of the measurement transducer, which corresponds to a caliber of the pipeline in whose course the measurement transducer is to be installed, amounts to at least 1.5, especially more than 2; and/or wherein an installed mass of the total measurement transducer is greater than 200 kg, especially greater than 400 kg. ### Claim 23 (depends on 1) Use of the measurement transducer as claimed in claim 1 for measuring a flowable medium conveyed in a pipeline having a caliber greater than 150 mm, especially greater than 250 mm or more and/or for measuring a mass flowrate of a medium flowing through a pipeline with a rate which is, at least at times, greater than 900 t/h, especially, at least at times, greater than 1200 t/h.