Mass flow gauge for flowing media with devices for determination of the Coriolis force
First Claim
1. A Coriolis mass flow gauge of the type including at least one tube loop having fixed legs and through which a fluid can flow, exciting means coupled to said loop to mechanically oscillate the loop at a selected frequency in a direction approximately perpendicular to the nominal plane of the loop, a lateral sensor at each leg of the loop which converts the oscillations of the loop into an analogous alternating voltage signal, and a dual channel electronic circuit which receives in separate channels the alternating signals from the sensors and produces an output that is proportional to the fluid mass flow through the loop, said gauge comprising:
- sampling means for producing a digital sampling signal having a selected frequency;
converter means responsive to said sampling signal for converting the sensor signal in each channel into digital measuring values;
processor means for multiplying each digital measuring value from the converter means, on the one hand, with the sine value of the phase angle at the point of sampling of the alternating voltage signal or another signal having the same frequency, but phase-shifted relative to said alternating voltage signal, and, on the other hand, with the corresponding cosine value of said phase angle;
means for storing said sine and cosine multiplication values;
means for summing(1) the stored sine multiplication values over a predetermined time interval to form one Cartesian coordinate of a corresponding sum-vector, and(2) the stored cosine multiplication values thus obtained over the same time interval to form another Cartesian coordinate of said sum vector, andmeans for calculating from said Cartesian coordinates of the sum vectors of both sensor signals the fluid mass flow through the loop.
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Accused Products
Abstract
In a Coriolis mass flow gauge, the signal from each sensor is digitized and converted into digital measuring values by one or more analog/digital converters operating with a specific digital sampling frequency. Then, using a microcomputer, each digital measuring value thus obtained is multiplied, on the one hand, with the sine value of the phase angle at the point of sampling of the alternating signal or another scanning signal with the same frequency as the alternating voltage signal, but phase-shifted against that signal and, on the other hand, with the corresponding cosine value. The sine-multiplication values thus obtained are summed over a predetermined time interval to form one Cartesian coordinate of a corresponding sum vector, whereas the cosine multiplication values thus obtained are summed over that time interval to form the other Cartesian coordinate of the sum vector, and from the Cartesian coordinates of the sum vectors of both lateral sensors, the measuring value describing the mass flow through the loop is calculated directly.
64 Citations
11 Claims
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1. A Coriolis mass flow gauge of the type including at least one tube loop having fixed legs and through which a fluid can flow, exciting means coupled to said loop to mechanically oscillate the loop at a selected frequency in a direction approximately perpendicular to the nominal plane of the loop, a lateral sensor at each leg of the loop which converts the oscillations of the loop into an analogous alternating voltage signal, and a dual channel electronic circuit which receives in separate channels the alternating signals from the sensors and produces an output that is proportional to the fluid mass flow through the loop, said gauge comprising:
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sampling means for producing a digital sampling signal having a selected frequency; converter means responsive to said sampling signal for converting the sensor signal in each channel into digital measuring values; processor means for multiplying each digital measuring value from the converter means, on the one hand, with the sine value of the phase angle at the point of sampling of the alternating voltage signal or another signal having the same frequency, but phase-shifted relative to said alternating voltage signal, and, on the other hand, with the corresponding cosine value of said phase angle; means for storing said sine and cosine multiplication values; means for summing (1) the stored sine multiplication values over a predetermined time interval to form one Cartesian coordinate of a corresponding sum-vector, and (2) the stored cosine multiplication values thus obtained over the same time interval to form another Cartesian coordinate of said sum vector, and means for calculating from said Cartesian coordinates of the sum vectors of both sensor signals the fluid mass flow through the loop. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification