VIBRATION-TYPE MEASURING SENSOR

摘要

The invention relates to a measuring sensor comprising a sensor housing (10), which has a plurality of natural vibration modes, and at least a first measuring tube (4) which is mounted inside the housing (10) so that it is able to vibrate at least intermittently and through which at least a partial volume of the medium to be measured is guided. The inventive measuring sensor further comprises an electromechanical, more particularly an electrodynamic, exciter arrangement (60) that acts upon the at least one measuring tube in order to generate and/or maintain mechanical vibrations of the at least one measuring tube (4), as well as a sensor arrangement which reacts to movements of the measuring tube (4), particularly to bending vibrations, and which serves to generate at least one vibration measuring signal (s_vb) representing vibrations of the measuring tube (4). In order to attenuate or suppress at least one natural vibration mode of the housing (10), the measuring sensor further comprises a first support element (13a) that is fixed, essentially directly, to the housing (10) and serves to generate in particular stationary vibration nodes in the housing (10). The housing and the at least one support element thus form an external oscillating system of the measuring sensor while the at least one measuring tube (4), the medium guided at least momentarily in said tube(s) and the at least partially exciter (60) and sensor arrangement (70) form an internal oscillating system of the measuring sensor. During operation of the measuring sensor, the internal oscillating system produces mechanical vibrations having at least one useful oscillation frequency (F_n) that depends not only on size, form and material of the measuring tube (4) but also on the actual density of the medium. During operation of the measuring sensor, said useful oscillation frequency can be modified within a predetermined useful frequency band (?F_n) comprising an upper and a lower limiting frequency. By using the support element, it is possible to produce vibration-type measuring sensors with large nominal diameters, i.e. more than 150 mm, and high measuring accuracy even if already established and proven constructions are essentially maintained.