US 5,965,824 A · Vibration type measuring instrument

Abstract

A vibration type measuring instrument measures at least one of density and mass flow rate of a fluid in a straight measurement pipe by vibrating the pipe. The vibration type measuring instrument comprises the pipe; a sensor for detecting the vibration of the pipe; and a signal processing circuit for obtaining the resonant angular frequency .omega. and axial force T based on the detection signal of the sensor, and obtaining the density .rho.w of the fluid flowing through the pipe using the obtained resonant angular frequency .omega. and axial force T. The density .rho.w is obtained by the following equation (E1). ##EQU1## (E: the Young's modulus of the pipe, I: a cross-sectional secondary moment of the pipe, Si: a cross-sectional area of the hollow portion of the pipe, .rho.t: a density of the pipe, St: the actual cross-sectional area of the pipe, L: the length in the axial direction of the pipe, x: a position in the axial direction of the pipe, y: a vibration amplitude of the pipe at position x, n: a number of masses added to the pipe, mk: a mass of a k-th added mass, and yk: a vibration amplitude of the k-th added mass).

Claims48

Dependent claims

A vibration type measuring instrument for measuring at least one of mass flow rate and density of a fluid flowing through a straight measurement pipe by vibrating the pipe, comprising:

a straight measurement pipe;
a vibration detecting means for detecting vibration of said measurement pipe;
and
signal processing means for obtaining a resonant angular frequency .omega. and axial force T of said measurement pipe based on a detection signal of said vibration detecting means, and obtaining a density .rho.w of the fluid flowing through said measurement pipe based on a following equation (E1) using the obtained resonant angular frequency .omega. and the axial force T, ##EQU11## where E indicates the Young's modulus of said measurement pipe, I indicates a cross-sectional secondary moment of said measurement pipe, Si indicates a cross-sectional area of a hollow portion of said measurement pipe, .rho.t indicates a density of said measurement pipe, St indicates an actual cross-sectional area of said measurement pipe, L indicates a length in an axial direction of said measurement pipe, x indicates a position in the axial direction of said measurement pipe, y indicates a vibration amplitude of said measurement pipe at position x, n indicates a number of masses added to said measurement pipe, mk indicates the mass of a k-th added mass, and yk indicates a vibration amplitude of the k-th added mass.

1 more element

A method of measuring at least one of mass flow rate and density of a fluid flowing through a straight measurement pipe by vibrating the pipe, comprising the steps of:

detecting a vibration of a straight measurement pipe;
obtaining a resonant angular frequency .omega. and axial force T based on the detected vibration of the measurement pipe;
and
obtaining a density .rho.w of the fluid flowing through the measurement pipe based on a following equation (E1) using the obtained resonant angular frequency .omega. and axial force T, ##EQU15## where E indicates the Young's modulus of the measurement pipe, I indicates a cross-sectional secondary moment of the measurement pipe, Si indicates a cross-sectional area of a hollow portion of the measurement pipe, .rho.t indicates a density of the measurement pipe, St indicates an actual cross-sectional area of the measurement pipe, L indicates a length in an axial direction of the measurement pipe, x indicates a position in the axial direction of the measurement pipe, y indicates a vibration amplitude of the measurement pipe at position x, n indicates a number of masses added to the measurement pipe, mk indicates a mass of a k-th added mass, and yk indicates a vibration amplitude of the k-th added mass.

1 more element

Dependencies are inferred from the claim text.

Vibration type measuring instrument

Life of this patent

Vibration type measuring instrument

Life of this patent

Abstract

Claims48