Measuring device, in particular a flow meter, with at least one ultrasonic transducer

Patent metadata

Field	Value
Publication number	US-11566929-B2
Application number	US-202017063786-A
Country	US
Kind code	B2
Filing date	Oct 6, 2020
Priority date	Feb 28, 2020
Publication date	Jan 31, 2023
Grant date	Jan 31, 2023

Abstract

A measuring device has at least one ultrasonic transducer and an evaluator for evaluating a measurement signal provided by the at least one ultrasonic transducer. The evaluator is set up to determine a first comparison signal, by comparing the measurement signal with a first switching threshold, and a second comparison signal, by comparing the measurement signal with a second switching threshold which is different from the first switching threshold, and to determine a signal amplitude of the measurement signal depending on the first and second comparison signal.

First claim

The invention claimed is:

1. A measuring device, comprising:
at least one ultrasonic transducer; and
an evaluator for evaluating a measurement signal provided by said at least one ultrasonic transducer, said evaluator is set up to determine a first comparison signal, by comparing the measurement signal with a first switching threshold, and a second comparison signal, by comparing the measurement signal with a second switching threshold which is different from the first switching threshold, and to determine a signal amplitude of the measurement signal depending on the first and second comparison signal.

2. The measuring device according to claim 1 , wherein the first comparison signal and/or the second comparison signal are square wave signals which assume a first value if the measurement signal falls below a respective switching threshold and a second value if the measurement signal exceeds the respective switching threshold.

3. The measuring device according to claim 2 , wherein said evaluator is set up to determine the signal amplitude depending on a time difference between a duration for which the first comparison signal assumes the first or second value and a duration for which the second comparison signal takes the first or second value.

4. The measuring device according to claim 3 , wherein said evaluator is set up to determine:
the duration for which the first comparison signal assumes the first or second value; and/or
the duration for which the second comparison signal assumes the first or second value; and/or
the time difference for a sampling window which contains a plurality of oscillation periods of the measurement signal.

5. The measuring device according to claim 3 , wherein:
said evaluator includes at least one logic gate and at least one time counter which is increased with a preset timing precisely when an input of said at least one time counter is supplied with a counter input signal having a predetermined value; and
said at least one counter is supplied with the first and/or second comparison signal and/or a result signal, which is determined depending on the first and second comparison signal, or an output signal of said at least one logic gate, which is supplied with the first and/or second comparison signal and/or the result signal as one of logic gate input signals, as the counter input signal, wherein the respective duration or the time difference are specified by a counter value of said at least one time counter.

6. The measuring device according to claim 5 , wherein said at least one logic gate is fed with a square wave signal as a further logic gate input signal, the square wave signal changes its value at a beginning and at an end of a sampling window, for which the signal amplitude and/or the duration for which the first comparison signal assumes the first or second value and/or the duration for which the second comparison signal assumes the first or second value is to be determined.

7. The measuring device according to claim 5 , wherein:
said evaluator is set up to determine the result signal as a difference signal between the first and second comparison signals; and/or
said evaluator contains at least one further logic gate, wherein said evaluator is set up in such a way that the first and second comparison signals are supplied to said at least one further logic gate as input signals and that an output signal of said at least one further logic gate is used as the result signal.

8. The measuring device according to claim 7 , wherein said at least one further logic gate is an exclusive OR gate.

9. The measuring device according to claim 3 , wherein said evaluator is set up to determine the signal amplitude by dividing a predetermined scaling factor by the time difference.

10. The measuring device according to claim 1 , wherein said evaluator has a respective D flip-flop with a clock input fed with a square wave signal which changes its value at a beginning and at an end of a sampling window, for which the signal amplitude and/or a duration for which the first comparison signal assumes the first or second value and/or a duration for which the second comparison signal assumes the first or second value is to be determined, and to a data input of which the first or second comparison signal or the result signal which is determined from the first and second comparison signal is in each case supplied, wherein said evaluator is set up to break off a determination of the signal amplitude and/or the respective duration for the sampling window or to discard the signal amplitude determined and/or the respective determined duration if the output of said D flip-flop has a predetermined value.

11. The measuring device according to claim 1 , wherein the first and second switching thresholds have signs which are different from one another.

12. The measuring device according to claim 11 , wherein said evaluator is set up to determine the first comparison signal during a first time interval by comparing the measurement signal with the first switching threshold and to determine the second comparison signal after an end of the first time interval during a second time interval by comparing the measurement signal with the second switching threshold.

13. The measuring device according to claim 12 , wherein:
said evaluator has a comparator; and
said evaluator has a control and evaluation circuit which is set up to set a comparator switching threshold of said comparator to the first switching threshold in the first time interval and to the second switching threshold in the second time interval.

14. The measuring device according to claim 1 , wherein said evaluator has:
a first comparator receiving the first switching threshold, said first comparator is set up to convert the measurement signal into the first comparison signal; and/or
a second comparator receiving the second switching threshold, said second comparator is set up to convert the measurement signal into the second comparison signal.

15. The measuring device according to claim 1 , wherein the measuring device is set up to repeatedly determine the signal amplitude and, in a case of at least one repetition, to specify the first and/or the second switching threshold depending on the signal amplitude determined previously.

16. The measuring device according to claim 1 ,
further comprising a measuring tube and through said measuring tube a fluid can flow;
wherein said at least one ultrasonic transducer is one of least two ultrasonic transducers which are disposed spaced apart from one another at said measuring tube; and
wherein said evaluator is set up to control in each case one of said ultrasonic transducers for exciting an ultrasonic wave in the fluid, and to determine a transit time of the ultrasonic wave between said ultrasonic transducers using the measurement data of the other said ultrasonic transducer, and to determine a flow rate and/or a flow volume of the fluid through said measuring tube depending on the transit time.

17. The measuring device according to claim 1 , wherein the measuring device is a flow meter.

18. The measuring device according to claim 1 , wherein the first and second switching thresholds have signs which are different from one another and have an equivalent value.

Assignees

• Diehl Metering Gmbh

Inventors

• Hofmann Alexander
• Gaugler Ulrich
• Wetzel Marcus

Classifications

• G01F1/667 Primary

  Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters · CPC title

• G01F25/10

  of flowmeters · CPC title

• G01F1/668

  Compensating or correcting for variations in velocity of sound · CPC title