Accuracy mass flow meter with asymmetry and viscous damping compensation
First Claim
Patent Images
1. A flow meter for flowable materials comprising:
- a. a support;
b. a continuous conduit which(1) is free of pressure sensitive joints,(2) is solidly mounted to said support at an inlet end and an outlet end of said conduit,(3) is characterized by the presence of an oscillation axis and a second axis, substantially transverse to said oscillation axis, about which Coriolis force acts when fluid is flowing through said conduit under oscillation conditions;
c. driver means for oscillating said conduit about said oscillation axis; and
d. sensor means for measuring motion of said conduit as a result of elastic deformation of said conduit around said second axis thereof upon oscillation of said conduit with fluid flow therethrough, thereby providing motion signals;
e. signal processing means, comprising;
(1) means for measuring frequency of oscillation of said conduit;
(2) logic means for converting said frequency of oscillation to a frequency response function;
(3) logic means for comparing said motion signals to determine a phase angle difference between said signals;
(4) logic means for converting said phase angle difference to a half-angle tangent function of said phase angle difference;
(5) logic means for mathematically combining said frequency response function, said frequency of oscillation and said half-angle tangent function with at least one calibration constant which comprisemeans to calculate mass flow rate mo according to the formulawhere ##EQU63## is a phase angle difference between output signals developed by said motion sensorstan (δ
θ
°
/2) is a half-angle tangent function;
K1 is a calibration constant proportional to a ratio of a bending force acting on said flow conduit to a viscous damping force acting on said flow conduit;
kc is an elastic spring constant of said flow conduit which is fixed at constant temperature and is otherwise temperature compensated;
##EQU64## is a frequency response function;
ω
d is a natural frequency of said flow conduit about said oscillation axis;
ω
c is a natural frequency of said flow conduit about said second axis,ζ
c is a damping coefficient about said second axis,whereby a mass flow rate measurement is obtained.
0 Assignments
0 Petitions
Accused Products
Abstract
An improved accuracy Coriolis mass flow meter. Signal processing embodiments provide improved accuracy by accounting for the non-linear relationship between phase angle difference of motion sensor signals and mass flow rate. Compensation is made for asymmetric and viscous damping effects, as well.
145 Citations
21 Claims
-
1. A flow meter for flowable materials comprising:
-
a. a support; b. a continuous conduit which (1) is free of pressure sensitive joints, (2) is solidly mounted to said support at an inlet end and an outlet end of said conduit, (3) is characterized by the presence of an oscillation axis and a second axis, substantially transverse to said oscillation axis, about which Coriolis force acts when fluid is flowing through said conduit under oscillation conditions; c. driver means for oscillating said conduit about said oscillation axis; and d. sensor means for measuring motion of said conduit as a result of elastic deformation of said conduit around said second axis thereof upon oscillation of said conduit with fluid flow therethrough, thereby providing motion signals; e. signal processing means, comprising; (1) means for measuring frequency of oscillation of said conduit; (2) logic means for converting said frequency of oscillation to a frequency response function; (3) logic means for comparing said motion signals to determine a phase angle difference between said signals; (4) logic means for converting said phase angle difference to a half-angle tangent function of said phase angle difference; (5) logic means for mathematically combining said frequency response function, said frequency of oscillation and said half-angle tangent function with at least one calibration constant which comprise means to calculate mass flow rate mo according to the formula where ##EQU63## is a phase angle difference between output signals developed by said motion sensors tan (δ
θ
°
/2) is a half-angle tangent function;K1 is a calibration constant proportional to a ratio of a bending force acting on said flow conduit to a viscous damping force acting on said flow conduit; kc is an elastic spring constant of said flow conduit which is fixed at constant temperature and is otherwise temperature compensated;
##EQU64## is a frequency response function;
ω
d is a natural frequency of said flow conduit about said oscillation axis;ω
c is a natural frequency of said flow conduit about said second axis,ζ
c is a damping coefficient about said second axis,whereby a mass flow rate measurement is obtained. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A flow meter for flowable materials comprising:
-
a. a support; b. a continuous conduit which (1) is free of pressure sensitive joints, (2) is solidly mounted to said support at an inlet end and an outlet end of said conduit, (3) is characterized by the presence of an oscillation axis and a second axis, substantially transverse to said oscillation axis, about which Coriolis force acts when fluid is flowing through said conduit under oscillation conditions; c. driver means for oscillating said conduit about said oscillation axis; d. sensor means for measuring motion of said driver means, thereby providing a driver motion signal; e. sensor means for measuring motion of said conduit as a result of elastic deformation of said conduit around said second axis thereof upon oscillation of said conduit with fluid flow therethrough, thereby providing motion signals; and f. signal processing means, comprising; (1) means for measuring frequency of oscillation of said conduit; (2) logic means for converting said driver motion signal to a damping measurement; (3) logic means for converting said frequency of oscillation and said damping measurement to a frequency response function and a Coriolis phase angle function; (4) logic means for comparing said driver motion signal and at least one of said flow conduit motion signals to determine a phase angle difference between said signals; (5) logic means for converting said phase angle difference and said Coriolis phase angle function to a trigonometric function of said phase angle difference; (6) logic means for mathematically combining said frequency response function, said frequency of oscillation and said trigonometric function with at least one calibration constant;
thereby producing a mass flow rate measurement. - View Dependent Claims (10, 11, 12)
-
-
13. A flow meter for flowable materials comprising:
-
a. a support; b. a continuous conduit which (1) is free of pressure sensitive joints, (2) is solidly mounted to said support at an inlet end and an outlet end of said conduit, (3) is characterised by the presence of an oscillation axis and a second axis, substantially transverse to said oscillation axis, about which Coriolis force acts when fluid is flowing through said conduit under oscillation conditions; c. driver means for oscillating said conduit about said oscillation axis; d. sensor means for measuring motion of said driver means, thereby providing a driver motion signal; e. sensor means for measuring motion of said conduit as a result of elastic deformation of said conduit around said second axis thereof upon oscillation of said conduit with fluid flow therethrough, thereby providing motion signals; and f. signal processing means, comprising; (1) means for measuring frequency of of oscillation of said conduit; (2) logic means for converting said driver motion signal to a damping measurement; (3) logic means for converting said damping measurement and said frequency of oscillation to a frequency response function and a Coriolis phase angle function; (4) logic means for comparing said driver motion signal and one of said flow conduit motion signals to determine a phase angle difference between said signals; (5) logic means for converting said phase angle difference and said Coriolis phase angle function to an asymmetry-compensated half-angle function; (6) logic means for converting said asymmetry-compensated half-angle function to a half-angle tangent function; (7) logic means for mathematically combining said frequency response function, said frequency of oscillation and said half-angle tangent function with at least one calibration constant;
thereby producing a mass flow rate measurement. - View Dependent Claims (14, 15, 16)
-
-
17. A flow meter for flowable materials comprising:
-
a. a support; b. a continuous conduit which, (1) is free of pressure sensitive joints, (2) is solidly mounted to said support at an inlet end and an outlet end of said conduit, (3) is characterized by the presence of an oscillation axis and a second axis, substantially transverse to said oscillation axis, about which Coriolis force acts when fluid is flowing through said conduit under oscillation conditions; c. driver means for oscillating said conduit about said oscillation axis; d. sensor means for measuring motion of said driver means, thereby providing a driver motion signal; e. sensor means for measuring motion of said conduit as a result of elastic deformation of said conduit around said second axis thereof upon oscillation of said conduit with fluid flow therethrough, thereby providing motion signals; and f. signal processing means, comprising; (1) means for measuring frequency of oscillation of said conduit; (2) logic means for converting said driver motion signal to a damping measurement; (3) logic means for converting said frequency of oscillation and said damping measurement to a frequency response function; (4) logic means for comparing said motion signals to determine a phase angle difference between said signals; (5) logic means for converting said phase angle difference to a half-angle tangent function of said phase angle difference; (6) logic means for mathematically combining said frequency response function, said frequency of oscillation and said half-angle tangent function with at least one calibration constant;
thereby producing a mass flow rate measurement. - View Dependent Claims (18, 19, 20, 21)
-
Specification