Device for determining and/or monitoring the volume flow rate and/or mass flow rate of a medium to be measured
First Claim
1. A device for determining and/or monitoring volume flow and/or mass flow of a medium flowing through a pipeline in a stream direction comprising:
- at least two ultrasonic transducers, which emit ultrasonic measuring signals into the pipeline and receive ultrasonic measuring signals from the pipeline; and
a control/evaluation unit, which ascertains the volume-flow and/or mass-flow of the medium in the pipeline on the basis of the travel-time difference of the ultrasonic measuring signals in the stream direction (S;
Up) and counter to the stream direction, wherein;
said control/evaluation unit ascertains a plurality of sampled values (ai with i=1, 2, 3, . . . ) of a received measuring signal at defined points in time (t) of a predetermined time range, interpolates the predetermined time range of the measuring signal by a continuous function (f(t)), the continuous function (f(t)) being formed by a sum of a predetermined number (n ∈
N) of wavelets (W), wherein each wavelet (W) corresponds to the product of a sampled value with a sine function and with a Gaussian bell curve (e−
α
x2,α
∈
R).
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Accused Products
Abstract
A ultrasonic flow measuring device, which is distinguished by a low energy consumption. A control/evaluation unit ascertains a plurality of sampled values (ai with i=1, 2, 3, . . . ) of a received measuring signal at defined points in time (t) of a predetermined time range and interpolates the sampled values by a continuous function (f(t)), wherein the continuous function (f(t)) is formed by a sum of a predetermined number (n ∈ N) of wavelets (W) and wherein each wavelet (W) corresponds to the product of a sampled value with a sine function
and with a Gaussian bell curve (e−αx
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Citations
9 Claims
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1. A device for determining and/or monitoring volume flow and/or mass flow of a medium flowing through a pipeline in a stream direction comprising:
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at least two ultrasonic transducers, which emit ultrasonic measuring signals into the pipeline and receive ultrasonic measuring signals from the pipeline; and a control/evaluation unit, which ascertains the volume-flow and/or mass-flow of the medium in the pipeline on the basis of the travel-time difference of the ultrasonic measuring signals in the stream direction (S;
Up) and counter to the stream direction, wherein;said control/evaluation unit ascertains a plurality of sampled values (ai with i=1, 2, 3, . . . ) of a received measuring signal at defined points in time (t) of a predetermined time range, interpolates the predetermined time range of the measuring signal by a continuous function (f(t)), the continuous function (f(t)) being formed by a sum of a predetermined number (n ∈
N) of wavelets (W), wherein each wavelet (W) corresponds to the product of a sampled value with a sine functionand with a Gaussian bell curve (e−
α
x2 ,α
∈
R).- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
and with a Gaussian bell curve (e−
α
x2 ,α
∈
R).
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3. The device as claimed in claim 1, wherein:
said control/evaluation unit determines an abscissa value (t), at which an ordinate value of the continuous function (f(t)) reaches a predetermined limit value.
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4. The device as claimed in claim 3, wherein:
the predetermined limit value of the continuous function (f(t)) is a zero point, a maximum, a minimum or an inflection point.
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5. The device as claimed in claim 1, wherein:
said control/evaluation unit determines an abscissa value (tmax, tmin) for a maximum and/or minimum on the basis of the first derivative f′
(t) of the continuous function f(t).
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6. The device as claimed in claim 1, wherein:
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said control/evaluation unit obtains an abscissa value (tmax), at which the continuous function reaches a maximum, by a linear interpolation of the first derivative of the continuous function (f(t)) according to the following formula; wherein t0 characterizes the abscissa value of a first approximation, at which a maximum or minimum is measured in the time interval (t0−
T, t0+T), and wherein f″
(t) represents the second derivative of the continuous function (f(t)).
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7. The device as claimed in claim 1, wherein:
said control/evaluation unit correlates, with one another, two ultrasonic measuring signals in two time ranges, interpolates the corresponding, discrete collection of correlation points by a continuous function (f(t)), and determines the abscissa value of the continuous function (f(t)), at which the ordinate value reaches a maximum value, the abscissa value being a measure for a time shift between ultrasonic measuring signals sent and received in the stream direction (S, Up) and counter to the stream direction (Down).
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8. The device as claimed in claim 1, wherein:
said calculating/control unit determines by means of a mathematical simulation program, in each case, an optimum value for the coefficient (α
) as a function of the number of measurement points (MaxSample).
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9. The device as claimed in claim 8, further comprising:
a memory unit, in which, in each case, the optimum value for the coefficient (α
) is stored as a function of the number of measurement points (MaxSample).
Specification