Patent ID: 8596143
Filing Date: 2013-12-03
Classification: G01F

Abstract:
1. A measuring system for measuring density and/or mass flow rate of a medium flowing in a pipeline said measuring system, comprising: a measuring transducer of the vibration type for producing oscillation measurement signals; and transmitter electronics electrically coupled with the measuring transducer for activating said measuring transducer and for evaluating oscillation measurement signals delivered from said measuring transducer, said measuring transducer includes: a transducer housing, with an inlet-side, first housing end formed by means of an inlet-side, first flow divider including four, mutually spaced, flow openings, and with an outlet-side, second housing end formed by means of an outlet-side, second flow divider including four, mutually spaced, flow openings; a tube arrangement including four, straight, measuring tubes forming flow paths arranged for parallel flow and connected to said flow dividers, of which measuring tubes: a first measuring tube opens with an inlet-side, first measuring tube end into a first flow opening of said first flow divider and with an outlet-side, second measuring tube end into a first flow opening of said second flow divider, a second measuring tube opens with an inlet-side, first measuring tube end into a second flow opening of said first flow divider and with an outlet-side, second measuring tube end into a second flow opening of said second flow divider, a third measuring tube opens with an inlet-side, first measuring tube end into a third flow opening of said first flow divider and with an outlet-side, second measuring tube end into a third flow opening of said second flow divider, and a fourth measuring tube opens with an inlet-side, first measuring tube end into a fourth flow opening of said first flow divider and with an outlet-side, second measuring tube end into a fourth flow opening of said second flow divider, and of which measuring tubes each one exhibits a middle segment, in which the respective measuring tube has no mechanical connection with any others of said measuring tubes and/or in which the respective measuring tube is freely movable relative to the other measuring tubes; an electromechanical exciter mechanism for producing and/or maintaining mechanical oscillations of said first, second, third and fourth measuring tubes; and a vibration sensor arrangement reacting to vibrations of said measuring tubes for producing oscillation measurement signals representing vibrations of said measuring tubes, said first, second, third and fourth straight measuring tubes are so embodied and so arranged in the measuring transducer: that the tube arrangement exhibits a first imaginary longitudinal section plane, relative to which the tube arrangement is mirror symmetric, said first imaginary longitudinal section plane lying both, between said first measuring tube and said third measuring tube as well as also between said second measuring tube and said fourth measuring tube, and the tube arrangement exhibits a second imaginary longitudinal section plane, relative to which the tube arrangement is likewise mirror symmetric, said second imaginary longitudinal section plane being perpendicular to said imaginary first longitudinal section plane and extending both, between said first measuring tube and said second measuring tube as well as also between said third measuring tube and said fourth measuring tube, and that a measuring tube length, corresponding to a minimum distance between the flow opening of said first flow divider corresponding to the respective inlet-side, first measuring tube end and the flow opening of said second flow divider corresponding to the respective outlet-side, second measuring tube end, amounts, for each of said measuring tubes to 1000 mm or more, and each of said middle segments providing at least 40% of the measuring tube length of the respective one of said first, second, third and fourth measuring tubes; and said transmitter electronics is adapted to feed electrical excitation power into said exciter mechanism by means of at least one electrical driver signal supplied to said exciter mechanism, wherein: the tube arrangement exhibits a natural bending oscillation mode of first type, in which said first measuring tube and said second measuring tube execute, relative to said second imaginary longitudinal section plane, opposite-equal—bending oscillations about, in each case, a static rest position associated with said respective measuring tube, and in which said third measuring tube and said fourth measuring tube execute, relative to said second imaginary longitudinal section plane, opposite-equal bending oscillations about, in each case, a static rest position associated with said respective measuring tube, in such a manner, that, relative to said second imaginary longitudinal section plane, said bending oscillations of said first measuring tube are also opposite-equal to said bending oscillations of said third measuring tube, and that, relative to said second imaginary longitudinal section plane, said bending oscillations of said second measuring tube are also opposite-equal to said bending oscillations of said fourth measuring tube; and said exciter mechanism is adapted to convert electrical excitation power at least partially both: into bending oscillations of said first measuring tube and into bending oscillations of said second measuring tube opposite-equal to bending oscillations of said first measuring tube relative to said second imaginary longitudinal section plane of the tube arrangement, as well as also into bending oscillations of said third measuring tube and into bending oscillations of said fourth measuring tube opposite-equal to the bending oscillations of said third measuring tube relative to said second imaginary longitudinal section plane of the tube arrangement, in such a manner that said four measuring tubes execute, at least partially bending oscillations in said natural bending oscillation mode of the first type.