JP4595656B2 - Fluid flow measuring device - Google Patents

Description

  The present invention relates to a fluid flow measuring device that measures the propagation time of ultrasonic waves using a pair of ultrasonic transducers capable of transmitting and receiving and measures the flow velocity and / or flow rate of a fluid to be measured.

  A conventional flow measurement device using ultrasonic waves has a pair of ultrasonic transducers facing upstream and downstream in the fluid flow direction, and drives one ultrasonic transducer with a burst signal. The ultrasonic wave was transmitted, the ultrasonic wave was received by the other ultrasonic transducer, and the ultrasonic propagation time was measured.

  FIG. 4 shows a driving waveform 12 of the ultrasonic transducer on the transmission side and a reception waveform 14 received by the ultrasonic transducer on the reception side. FIG. 4 shows time on the horizontal axis and voltage on the vertical axis. In the figure, T0 indicates the start point of the drive waveform 12, and T1 indicates the end point of the third wave after the start of drive. R0 indicates the reception start time, and R1 indicates the third wave end time after the reception starts.

  Thus, the zero-cross point T1 of the m-th (m = 3) wave of the drive waveform is the starting point, and the m-th (m = 3) wave of the electrical signal received by the other ultrasonic transceiver is the end point R1. The time Tp between the start point T1 and the end point R1 is measured as an ultrasonic propagation time, the flow velocity of the fluid is measured using the propagation time, and the flow rate is calculated from the flow velocity as necessary (for example, , See Patent Document 1).

  In order to determine the zero cross point of the third wave, the reference voltage 13 is set in advance between the amplitudes of the second wave and the third wave, and the next zero cross when the received signal exceeds the reference voltage 13 is determined. The third wave is set.

  FIG. 5 shows a conventional fluid flow measuring apparatus. This apparatus includes a pair of ultrasonic transducers 2a and 2b provided on the upstream side and the downstream side of a fluid flow path 1 through which a fluid to be measured flows, a drive circuit 3 for driving the ultrasonic transducers 2a and 2b, A control unit 4 that outputs a start signal to the drive circuit 3, a propagation time measurement unit 5 that measures the propagation time of the ultrasonic wave, an amplifier 6 that amplifies the output of the ultrasonic transducer 2a or 2b on the receiving side, and this amplifier 6 is compared with a reference voltage, and a reception detection circuit 7 that stops the propagation time measurement unit 5 when the magnitude relationship is reversed is formed.

In addition, in order to use the inverse propagation time difference method that can ignore the influence of temperature on the sound speed, the propagation time of the ultrasonic wave from the upstream side to the downstream side of the fluid flow path 1 and the propagation time from the downstream side to the upstream side are measured. A changeover switch 8 is provided so that it can be used.
JP-A-9-33308

  However, due to failure of the ultrasonic transducer, condensation, adhesion of foreign matter, etc., the received waveform changes, and the signal cannot be received at the normal zero cross point, resulting in an error from the true propagation time. In spite of the reduced accuracy, there was a problem that could not be distinguished from the correct measured flow rate.

  The present invention solves the above-mentioned conventional problems, and recognizes a change in the received waveform of ultrasonic waves, and when the measurement accuracy is reduced, displays an abnormality and prevents the adoption of erroneous measurement results. With the goal.

In order to solve the conventional problem, the present invention receives a pair of ultrasonic transducers arranged on the upstream side and the downstream side of a fluid flow path, and an ultrasonic wave propagation time between the ultrasonic transducers. A propagation time measurement unit that measures the propagation time until the end of the m-th wave of the waveform, and a control unit that obtains the flow velocity and / or flow rate of the fluid flowing through the fluid flow path based on the propagation time measured by the propagation time measurement unit And a received waveform frequency measuring unit that measures the frequency of the received waveform from the difference between the propagation time until the end time of the first wave and the propagation time until the end time of the second wave of the received waveform received by the ultrasonic transducer And a display unit that displays an abnormality when the frequency of the received waveform measured by the received waveform frequency measuring unit has changed by a predetermined value or more from the initial value.

  As a result, if the amplitude of the received waveform changes due to failure of the ultrasonic transducer, condensation, foreign matter, etc., a measurement error will be displayed, so the flow rate and / or flow rate will be measured with reduced measurement accuracy. Can be prevented.

The ultrasonic flowmeter of the present invention can prevent the flow rate and flow rate from being measured while the measurement system is lowered when the received waveform changes due to failure of the ultrasonic transducer, condensation, adhesion of foreign matter, etc. Therefore, reliable measurement is possible.

According to a first aspect of the present invention, a pair of ultrasonic transducers arranged on the upstream side and downstream side of a fluid flow path, and the propagation time of the ultrasonic wave between the ultrasonic transducers are measured at the end of the m-th wave of the received waveform. a propagation time measurement unit for measuring a propagation time to a control unit for determining the flow velocity and / or flow rate of the fluid flowing through the fluid flow path based on the propagation time measured by the propagation time measuring unit, with the ultrasonic vibrator A received waveform frequency measuring unit that measures the frequency of the received waveform from the difference between the propagation time until the end of the first wave of the received waveform and the propagation time until the end of the second wave; and the received waveform frequency measuring unit And a display unit that displays an abnormality when the frequency of the received waveform measured in (1) changes more than a predetermined value from the initial value.

According to the first inventions, failure or the ultrasonic vibrator, condensation, by foreign matter such as adhesion, when the frequency of the received waveform is changed, the display of the measurement abnormality is made.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

( Reference Example 1)
Reference Example 1 of the present invention will be described below with reference to FIGS. In addition, about the structure which show | plays the same effect | action as FIG.4, 5 used by description of background art, the same code | symbol was attached | subjected for convenience.

  That is, the ultrasonic transducers 2a and 2b are provided upstream and downstream of the fluid flow path 1 through which the fluid to be measured flows, and these ultrasonic transducers 2a or 2b are driven by the drive circuit 3.

  In addition, the control unit 4 that outputs a start signal to the drive circuit 3, the propagation time measurement unit 5 that measures the propagation time of the ultrasonic wave between the ultrasonic transducers 2a and 2b, and the ultrasonic transducer 2a on the receiving side or An amplifier 6 that amplifies the output of 2b, a reception detection circuit 7 that stops the propagation time measurement unit 5 when the magnitude relation is inverted compared to the output of the amplifier 6 and a reference voltage, and ultrasonic transducers 2a and 2b Switch 8 for switching between transmission and reception, received waveform amplitude measuring unit 9 for measuring the amplitude from the first wave to the peak wave of the received waveform received by the ultrasonic transducer 2a or 2b, and the amplitude ratio of the received waveform is initial A display unit 10 is provided for displaying an abnormality when the value has changed from a value by a predetermined value or more.

  The operation and action of the above configuration will be described below.

First, the basic measurement operation is the same as the description of FIGS. 4 and 5 described in the background art. The feature of the present reference example is that a received waveform amplitude measuring unit 9 and a display unit 10 are provided.

  The operation of the received waveform amplitude measuring unit 9 will be described with reference to FIG.

The reception waveform amplitude measurement unit 9 may store the reference voltage 13 for detecting the reception, a voltage of varying propagation time by increasing little by little from a low voltage as the respective amplitude of the received wave.

For example, although when the reference voltage 13-1 and the reference voltage 13-a propagation time is Ta, the reference voltage 13-2 propagation time is Tb. Thus, seen as the place where propagation time is switched to Tb from Ta is the amplitude of the first wave eyes of the received wave.

  In this way, the amplitude from the first wave to the peak wave can be measured. In this embodiment, the control unit 4 measures and stores the amplitude of each of the initial received waves, and the received waveform amplitude measuring unit 9 determines the peak from the first wave of the received waveform every predetermined period. When the amplitude up to the wave is measured and fluctuates from a predetermined value, the display unit 10 displays that the measuring device is abnormal.

As described above, in the present embodiment, by providing the received waveform amplitude measurement section 9 and the display section 10, failure or the ultrasonic vibrator, condensation, by foreign matter such as adhesion, when the amplitude of the received waveform is changed Since the measurement abnormality is displayed, it is possible to prevent the flow rate from being measured while the measurement accuracy is lowered.

(Embodiment 1 )
FIG. 3 shows a first embodiment of the present invention, in which ultrasonic transducers 2a and 2b are provided upstream and downstream of a fluid flow path 1 through which a fluid to be measured flows, and these ultrasonic transducers 2a or 2b are Driven by the drive circuit 3.

  In addition, the control unit 4 that outputs a start signal to the drive circuit 3, the propagation time measurement unit 5 that measures the propagation time of the ultrasonic wave between the ultrasonic transducers 2a and 2b, and the ultrasonic transducer 2a on the receiving side or An amplifier 6 that amplifies the output of 2b, a reception detection circuit 7 that stops the propagation time measurement unit 5 when the magnitude relation is inverted compared to the output of the amplifier 6 and a reference voltage, and ultrasonic transducers 2a and 2b Switch 8 for switching between transmission and reception, reception waveform frequency measurement unit 15 for measuring the frequency of the reception waveform received by the ultrasonic transducer, and abnormal when the frequency of the reception waveform has changed from the initial value by a predetermined value or more Is displayed.

  About the ultrasonic flowmeter comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

First, the basic flow rate measuring operation is the same as the description of FIGS. 4 and 5 described in the background art. The feature of this embodiment is that a received waveform frequency measuring unit 15 and a display unit 10 are provided. The operation of the reception waveform frequency measurement unit 15 will be described with reference to FIG. The received waveform frequency measurement unit, a reference voltage 13 for detecting the reception, by increasing little by little from a low voltage, and propagation time Ta at which the reference voltage is between the zero reference voltage and the first wave th amplitude seeking propagation time Tb when in between the first wave and second-wave first amplitude, than the difference between Tb and Ta, it is possible to determine the frequency of the received waveform.

  In the measuring apparatus according to the present embodiment, the control unit 4 measures and stores the frequency of the initial received wave, and the received waveform frequency measuring unit 15 measures the frequency of the received waveform every predetermined period. When the value fluctuates from the value, the display unit 10 displays that the device is abnormal.

  As described above, in the present embodiment, the reception waveform frequency measurement unit 15 and the display unit 10 are provided, so that the frequency of the reception waveform has changed due to failure of the ultrasonic transducer, condensation, adhesion of foreign matter, and the like. In this case, since a measurement abnormality is displayed, it is possible to prevent the flow velocity and / or flow rate from being measured while the measurement accuracy is lowered.

  As described above, the fluid flow measurement device according to the present invention displays a measurement abnormality when the frequency or amplitude of the received waveform changes due to a failure of the ultrasonic transducer, condensation, adhesion of foreign matter, or the like. Therefore, it is possible to prevent the flow rate from being measured while the measurement accuracy is lowered, and it can be applied to applications such as a measurement standard device and a gas meter or a water meter that require high reliability.

Configuration diagram of a flow measurement apparatus according to Embodiment 1 of the present invention Transmission / reception waveform diagram The block diagram of the flow measuring apparatus in Embodiment 2 of this invention Transmission / reception waveform diagram of a conventional flow measurement device Configuration diagram of a conventional flow measurement device

DESCRIPTION OF SYMBOLS 1 Fluid flow path 2a, 2b Ultrasonic transducer 4 Control part 5 Propagation time measurement part 9 Reception waveform amplitude measurement part 10 Display part 15 Reception waveform frequency measurement part

Claims (1)

A pair of ultrasonic transducers oppositely arranged upstream and downstream of the fluid flow path, measuring the ultrasonic wave propagation time between the ultrasonic vibrator as the propagation time to the end time of the m-wave th received waveform a propagation time measurement unit for, the control unit determining the flow rate and / or flow rate of the fluid flowing through the fluid flow path based on the propagation time measured by the propagation time measuring unit, the received waveform received by the ultrasonic vibrator 1 A received waveform frequency measuring unit that measures the frequency of the received waveform from the difference between the propagation time until the end of the wave and the propagation time until the end of the second wave, and the received waveform measured by the received waveform frequency measuring unit. A fluid flow measuring device comprising: a display unit that displays an abnormality when the frequency changes from an initial value by a predetermined value or more.

Images