JPS5594138A - Vibration type densimeter - Google Patents

Abstract

PURPOSE: To provide a vibration type densimeter which has excellent temperature characteristics without drift by providing a vibrator and a drive unit for simultaneously vibrating the vibrator in a plurality of vibration modes and obtaining the density of a fluid to be measured around the vibrator from the plural natural vibration frequencied thereof.

CONSTITUTION: This densimeter comprises a cylindrical vibrator 1 fixed at its one end, piezo-electric element 2, 3 for detecting vibration, and driving piezo-electric elements 4, 5 to be mounted in the vicinity of the center of the loop of the vibration mode to be obtained, wherein the elements 2W5 incorporate the same characteristics and are provided in space at 90° each other. The outputs from the elements 2, 3 are applied to a charge amplifier 6. The outputs from the amplifier 6 are multiplied by predetermined values at coefficient circuits 8, 9, respectively, and processed in an adder 10 and a subtractor 11. The outputs from the adder 10 and the subtractor 11 are respectively applied through low pass filters 12, 13, respectively to amplifiers 14, 15, respectively, which produces voltages having constant amplitude. These voltage outputs from the amplifiers 14, 15 are added by an adder 16. The sum output from the adder 16, is applied to the element 4. The output from the amplifier 14 is subtracted by the output from the amplifier 15 by a subtractor 17, which produces a subtracted output signal. The signal from the subtractor 17 is applied to the element 5. The output signals Ve, Vf from the amplifiers 14, 15, respectively are applied to an output circuit 18, which thereupon produces a signal corresponding to the density of fluid to be measured.

COPYRIGHT: (C)1980,JPO&Japio