JPH088417Y2 - Ultrasonic flowmeter calibration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a calibration device for an ultrasonic gas flow meter that measures the flow rate of gas flowing in a pipeline.

[Background Art] Generally, in an ultrasonic flow meter, when ultrasonic waves propagate in a fluid, the propagation time differs depending on whether the ultrasonic waves travel from upstream to downstream or from downstream to upstream, and the time difference between the two is proportional to the flow velocity. The flow rate is calculated by utilizing the above, and is multiplied by the pipe cross-sectional area, and the flow rate is calculated by performing a correction calculation corresponding to the flow rate distribution. Since this flow meter is a device that measures the amount of flowing fluid, it is difficult to measure the true value of the measuring device. Therefore, it is necessary to make adjustments one by one in order to realize the accuracy of the measurement, and to check the accuracy of the measurement one by one at an appropriate flow point.

Conventionally, as this type of calibration device, there is one shown in FIGS. 5 and 6.

FIG. 5 shows what is called a reference tank system. This is calibrated by utilizing the fact that the flow rate can be measured if the time and speed of outflow, the pipe cross-sectional area of the outflow part, etc. are known because the volume in the tank is constant.

FIG. 6 shows calibration using a sonic nozzle. The sonic nozzle is a nozzle that generates a constant flow rate by utilizing the phenomenon that when the passing flow velocity reaches the sonic velocity, the flow velocity does not increase further. When using this sonic nozzle, stability of gas components, pressure, temperature, and humidity, and accurate time measurement are required. Various other calibration devices are also known.

[Problems to be Solved by the Invention] However, the conventional ultrasonic flowmeter calibration device has a gas tank, a pressure component, and a temperature component that are provided with a reference tank in addition to the ultrasonic flowmeter or in actual calibration measurement. However, there is a drawback that the user cannot calibrate easily because of the stability of humidity, the necessity of accurate time measurement, and the like, and the calibration must be performed only by a specific institution.

In addition, there is a drawback that a lot of time and cost must be spent to maintain the accuracy of the calibration device and perform the calibration.

An object of the present invention is to eliminate the above-mentioned drawbacks and to provide an ultrasonic flowmeter calibration device that can be easily calibrated by the user.

[Means for Solving the Problem] The present invention provides an ultrasonic flowmeter calibration device in the propagation time measured path of an ultrasonic flowmeter equipped with a transducer, and the calibration device has a detection signal from the transducer. Corresponding to the time generating means for forming a signal having a predetermined time width, and a wave receiving means for generating an ultrasonic mimicking reception signal formed by the time generating means after a predetermined time has elapsed. is there.

Embodiment Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is an embodiment of the present invention and shows an example in which an ultrasonic flowmeter calibration device is applied to the path of an ultrasonic flowmeter.

In FIG. 1, reference numeral 1 is a pipeline through which a fluid flows. Reference numerals 2 and 3 denote electro-acoustic conversion elements that form an ultrasonic sensor, and are fixed by abutting on the outer surface of the conduit 1.
This sensor transmits ultrasonic waves emitted from a wave transmitter with two elements for a certain period of time through a fluid in a pipe and receives them with an element 3 to measure an ultrasonic wave propagation time T1. Is emitted as a wave transmitter and is received by the element 2, the ultrasonic wave propagation time T2 is measured and calculated, and the flow rate inside the pipe is measured. The elements 2 and 3 are composed of vibrators made of ceramic piezoelectric elements or the like.

In this embodiment, the element 2 will be described as the + side and the element 3 will be described as the − side. The lines 21 and 31 drawn from the elements 2 and 3 respectively are connected to the terminals 4a and 4b in the switch circuit 4. The contacts 4a and 4b are connected to the + side and − side of the converter 5 via the switch 41. This converter 5 is an element 2
And a device for calculating an ultrasonic wave propagation signal obtained by a detector such as 3 and converting it into a display value or an output signal as a flow rate value. On the other hand, the switch 41 is configured to be able to switch to the other contacts 4c and 4b of 4a and 4b. These 4c and 4b are input-connected to the + side 61 and-side 62 of the calibration device 6, respectively. The switch circuit 4 is configured so that the control means composed of a microcomputer (not shown) or the like switches the switch at a predetermined timing to perform calibration measurement.

FIG. 2 is a schematic block diagram showing the configuration of the calibration device 6.

The switch 41 in the switch circuit 4 is set at a predetermined timing.
When switching to 4c and 4d side, input terminal 61 and
The + and-signals input to 62 are input to the switching circuit 7. Since the signal at this time corresponds to the communication signal between the converter 5 and the wave transmitters / receivers 2 and 3, it does not always match the true value. The signal input to the switching circuit 7 is output (71, 72) to both the control circuit 8 and the time control circuit 9. The control circuit 8 has a built-in clock generation circuit for generating clock pulses, a clock counting circuit for counting clocks, and the like. Therefore, the trigger pulse signal 81 corresponding to the + signal and the-signal output from the switching circuit 7 is output to the time control circuit 9 at a predetermined timing. Further, the time control circuit 9 forms a pulse having a predetermined time width in synchronization with the pulse signal 81 of the control circuit 8 and outputs the pulse to the received wave generation circuit 10. The received wave generation circuit 10 generates burst signals at t1 and t2 after a lapse of a predetermined time generated by the time control circuit. The times t1 and t2 are set so that the ultrasonic wave propagation time has a delay time corresponding to the propagation time corresponding to the flow rate value to be calibrated. This time width is configured to be variable in the control circuit 8. The burst signal generation timing of the received wave generation circuit 10 is generated in synchronization with the trigger pulse of the output signal 82 of the control circuit 8 and therefore is accurately measured. This burst signal is generated after the lapse of time t1 and t2 as shown in FIG. 3, but forms a similar signal corresponding to the frequencies of the transducers 2 and 3. The signal 101 output from the received wave generation circuit 10
Is input to the switching circuit 7.

The operation of the present invention configured as described above will be described with reference to the timing chart of FIG.

When the input signals 61 and 62 are alternately input as a whisker-shaped pulse to the calibration device 6, the switching circuit 7 generates a pulse having a predetermined width in synchronization with the pulse 61 and 62. The control circuit 8 also outputs a trigger pulse in synchronization with the rising pulse or the falling pulse of the switching circuit 7 for a predetermined time t1.
Or measure t2 time. In synchronization with this measurement pulse, the time control circuit 9 and the received wave generation circuit 10 form a pulse having a predetermined time width and generate a burst signal. The pseudo burst signal formed by the received wave generation circuit 10 is sent to the converter 5 to calibrate the measured value in the converter to a true value.

In the present invention, the control circuit, the time control circuit, and the like in the calibration device are described as separate configurations, but they may be appropriately modified or improved as long as they have the same operation.

[Effects of the Invention] As described above, according to the present invention, large-scale equipment such as a conventional reference tank is not required, and gas components, pressure, temperature, and humidity can be measured in actual calibration measurement. Since stability and accurate time measurement can be performed without being restricted by measurement conditions, the user can easily measure and calibrate. Further, there is an effect that much time and cost are not required for maintaining the accuracy of the calibration device and performing calibration.

[Brief description of drawings]

FIG. 1 is an embodiment of the present invention, showing an example of application of an ultrasonic flowmeter calibration device to the path of an ultrasonic flowmeter, and FIG. 2 is a schematic block diagram showing the configuration of the calibration device 6 of the present invention. 3 and 4 are diagrams showing a timing chart of the present invention, and FIGS. 5 and 6 are diagrams showing a conventional ultrasonic flowmeter calibration apparatus. 1 ... Pipe line, 2, 3 ... Ultrasonic element, 4 ... Switch circuit, 41 ... Switch, 4a, 4b, 4c, 4d ... Switch contact,
5 ... Converter, 6 ... Calibration device, 7 ... Switching circuit, 8 ...
… Control circuit, 9 …… Time control circuit, 10 …… Reception generating circuit.

Claims (1)

[Scope of utility model registration request] 1. An ultrasonic flowmeter calibration device is provided in a propagation time non-measuring path of an ultrasonic flowmeter equipped with a transducer, and the calibration device has a predetermined time width corresponding to a detection signal from the transducer. Ultrasonic flowmeter, characterized in that it is provided with a time generating means for forming the pulse signal of 1 and a receiving wave generating means for generating an ultrasonic pseudo reception signal after a predetermined time formed by the time generating means. Calibration device