FLOW MEASUREMENT DEVICE

• US 20110238332A1
• Filed: 12/12/2008
• Published: 09/29/2011
• Est. Priority Date: 12/19/2007
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Takemura, Koichi, Shiba, Fumikazu, Bessyo, Daisuke
• Granted Patent: US 8,903,663 B2
• Time in Patent Office: Days
• US Class Current: 702/48
• CPC Class Codes: G01F 1/662 Constructional details
• CPC Class Codes: G01F 1/667 Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters

Abstract

To find the propagation time of an ultrasonic wave, a difference occurs between the waveforms received upstream and downstream in a portion where the reception amplitude is comparatively large and it is prevented from being detected as an error of the propagation time. A reception signal is amplified in a reception unit 35 and reception point storage units 38 store the most recent reception point data in a plurality of storage sections in order until the signal level becomes a predetermined value (Vref). An average value of the two zero crossing points before and after the signal level becomes Vref can be adopted as a reception point, the propagation time with a small error of up and down offset, etc., is measured, and it is made possible to realize power saving operation by shortening the measurement time.

Claims

1. A flow measurement device comprising:

a pair of vibrators being placed in a flow path where a measured fluid flows for transmitting and receiving an ultrasonic wave;

a transmission device for driving one vibrator;

a reception unit for converting an output signal of the other receiving-side vibrator into an electric signal;

a reception wave determination unit for outputting a signal when the signal of said reception unit becomes a predetermined value;

a reception point detection unit for outputting a signal when the signal of said reception unit becomes a predetermined range;

at least two reception point storage units for storing output of said reception point detection unit;

a time count unit for counting the propagation time of an ultrasonic wave signal propagating between said vibrators using each signal of said reception point storage units;

a flow rate computation unit for calculating the flow rate based on the time count difference of said time count unit; and

a control unit for controlling at least one of said transmission unit, said reception unit, said reception wave determination unit, said reception point detection unit, said reception point storage units, said time count unit, and said flow rate computation unit.

2. The flow measurement device as claimed in claim 1, wherein two or more reception point storage units are provided.

3. The flow measurement device as claimed in claim 1, wherein said reception point storage units overwrite data for update until an output signal of said reception wave determination unit comes.

4. The flow measurement device as claimed in claim 1, wherein said control unit has a power supply unit for energizing said reception point storage units for storing output of said reception point detection unit for a long time only the first time.

5. The flow measurement device as claimed in claim 1, wherein said control unit has a power supply unit for controlling the energizing time and adjusts the timing of the power supply unit so as to energize said reception point storage units for storing output of said reception point detection unit for a short time based on the preceding value at the second or later time.

6. The flow measurement device as claimed in claim 1, wherein said control unit has a power supply unit for controlling the energizing time and a trigger unit for outputting a signal when said reception point detection unit outputs exceeding a predetermined number of times and the power supply unit starts energizing said reception point storage units for storing output of said reception point detection unit according to output of the trigger unit.

7. The flow measurement device as claimed in claim 1, wherein said control unit has a power supply unit for stopping power supply to said reception point storage units after the expiration of a predetermined time after output of said reception point detection unit after output of said reception wave determination unit.

8. The flow measurement device as claimed in claim 1, wherein said control unit has a storage control unit for adjusting so that data in said reception point storage units is overwritten in order starting at the oldest data.

9. The flow measurement device as claimed in claim 1, wherein said control unit has a reception point selection unit for selecting the value in said reception point storage units retroacting only a predetermined number according to output of said reception wave determination unit for propagation time computation.

10. The flow measurement device as claimed in claim 1, wherein said control unit has a time certification unit for computing the difference between the value in said reception point storage units retroacting only a predetermined number according to output of said reception wave determination unit and output of said reception wave determination unit and if the value of the time certification unit is within a predetermined value, measurement is determined valid measurement.

11. The flow measurement device as claimed in claim 3 wherein said control unit has a time certification unit for computing the difference between output of said reception point detection unit after output of said reception wave determination unit and the value in said reception point storage units and if the value of the time certification unit is within a predetermined value, measurement is determined valid measurement.

12. (canceled)