JP5454389B2 - Flow measuring device - Google Patents

Description

  The present invention relates to a flow rate measuring apparatus that measures the flow of a fluid such as gas or water using ultrasonic waves.

  A conventional fluid flow rate measuring apparatus of this type is generally as shown in FIG. 5 (see, for example, Patent Document 1-Claim 1). This apparatus includes a first ultrasonic transducer 12 and a second ultrasonic transducer 13 installed in a flow path 11 through which a fluid to be measured flows, temperature measuring means 18 for measuring the actual temperature of the fluid to be measured, and first ultrasonic waves. Propagation time measuring means 14 for driving the vibrator 12 and the second ultrasonic vibrator 13 to measure the propagation time of transmission / reception of ultrasonic signals, a control means 17 for controlling the measurement timing in the propagation time measuring means 14, and propagation A flow rate calculation unit 15 that calculates a flow rate from the propagation time measured by the time measurement unit 14 and a flow rate correction unit 16 that corrects the flow rate calculated according to the temperature measured by the temperature measurement unit 18 to a flow rate at a desired temperature. It is composed of

  In this apparatus, the control means 17 operates the propagation time measuring means 14 at the measurement timing. The propagation time measuring unit 14 drives the first ultrasonic transducer 12 and the second ultrasonic transducer 13 based on an instruction from the control unit 17 and determines the propagation time of the ultrasonic signal transmitted / received between both ultrasonic transducers. taking measurement. The flow rate calculation means 15 calculates the flow velocity and flow rate of the fluid to be measured flowing through the flow path 11 from the propagation time measured by the propagation time measurement means 14. The temperature measuring means 18 measures the actual temperature of the fluid to be measured. The flow rate correction unit 16 corrects the flow rate calculated by the flow rate calculation unit 15 from the actual temperature measured by the temperature measurement unit 18 to a flow rate at a desired temperature.

  Further, a conventional flow measuring device of this type of fluid as shown in FIG. 6 is generally used (for example, refer to Patent Document 1 to Claim 4). This apparatus drives the first ultrasonic transducer 12 and the second ultrasonic transducer 13, and the first ultrasonic transducer 12 and the second ultrasonic transducer 13 installed in the flow path 11 through which the fluid to be measured flows, and is supersonic. The propagation time measuring means 14 for measuring the propagation time of transmission / reception of the sound wave signal, the control means 17 for controlling the measurement timing in the propagation time measuring means 14, and the flow rate is calculated from the propagation time measured by the propagation time measuring means 14. The flow rate calculation means 15 and the flow rate correction means 16 that corrects the flow rate calculated by the flow rate calculation means 15 according to the fluid temperature calculated from the propagation time measured by the propagation time measurement means 14.

  In this apparatus, the control means 17 operates the propagation time measuring means 14 at the measurement timing. The propagation time measuring unit 14 drives the first ultrasonic transducer 12 and the second ultrasonic transducer 13 based on an instruction from the control unit 17 and determines the propagation time of the ultrasonic signal transmitted / received between both ultrasonic transducers. taking measurement. The flow rate calculation means 15 calculates the flow velocity and flow rate of the fluid to be measured from the propagation time measured by the propagation time measurement means 14. The flow rate correcting unit 16 corrects the flow rate calculated by the flow rate calculating unit 15 to a flow rate at a desired temperature based on the temperature of the fluid to be measured calculated from the propagation time measured by the propagation time measuring unit 14.

Here, generally, the sound velocity C and the temperature T of gas can be approximated by a linear expression. That is, C = A × T + C0 A: Temperature coefficient C0: Sound velocity of the gas at 0 ° C.

Further, since the propagation time t of the ultrasonic signal is a value obtained by dividing the distance L between the first ultrasonic transducer 12 and the second ultrasonic transducer 13 by the sound velocity of the fluid,
t = L / C = L / (A × T + C0)
It can be expressed as.

Therefore,
T = (L / t-C0) / A
Thus, when the fluid to be measured flowing through the flow path is known in advance, the temperature coefficient A of sound velocity and the sound velocity C0 at 0 ° C. are constants, so that the fluid temperature T can be calculated from the propagation time t.

  Thus, the flow temperature at the desired temperature is corrected by calculating the temperature of the fluid from the propagation time of the ultrasonic waves.

Japanese Patent Laid-Open No. 2001-241988

  However, in the conventional flow rate measuring apparatus using the temperature measuring unit 18, a thermistor is generally used for the temperature measuring unit 18, but there is a problem that power consumption becomes large because it is necessary to supply power to the thermistor.

  Further, the above-described conventional flow rate measuring device that calculates the temperature of the fluid to be measured from the propagation time without using the temperature measuring means 18 has a problem that it is necessary to specify the fluid to be measured although low power consumption can be realized. It was.

  In other words, the conventional flow rate measuring device has a problem in that it is impossible to achieve both low power consumption and compatibility with repetitive types of fluids to be measured.

  An object of the present invention is to solve the above-mentioned conventional problems, and to provide a flow rate measuring device capable of correcting the measured flow rate to a flow rate at a desired temperature with low power consumption for a plurality of types of fluids to be measured. To do.

In order to solve the above-described conventional problems, a flow rate measuring device according to the present invention includes a first vibrator and a second vibrator that are provided in a fluid conduit and transmit / receive an ultrasonic signal, and a fluid to be measured that flows in the fluid conduit. Temperature measuring means for measuring the temperature of the apparatus, propagation time measuring means for driving the vibrator to measure the propagation time of transmission / reception of ultrasonic signals, and control for controlling the measurement timing of the temperature measuring means and the propagation time measuring means Means, a flow rate calculating means for calculating a flow rate from the propagation time of the ultrasonic signal measured by the propagation time measuring means, and a fluid temperature to be measured is calculated from the propagation time measured by the propagation time measuring means, and this calculation is performed. based on the temperature, the flow rate measuring apparatus having a flow rate correction means, a for temperature correction to the flow rate of the flow rate calculated by the calculating means at the desired temperature, the flow rate correction means, the fluid to be measured temperature -Until the propagation time characteristic can be specified, the temperature of the fluid to be measured is calculated based on the temperature measured by the temperature measuring means. After the temperature-propagation time characteristic of the fluid to be measured is specified, the propagation time measuring means is used. The temperature of the fluid to be measured is calculated based on the measured propagation time .

  Then, the temperature-propagation time characteristic of the fluid to be measured (or temperature-sound velocity characteristics) may be specified from the measurement results of the propagation time and the actual temperature of the fluid to be measured, and the temperature of the fluid to be measured may be determined from the propagation time. The temperature is calculated and corrected to the flow rate at a desired temperature.

As a result, until the temperature-propagation time characteristic of the fluid to be measured is initially specified, the temperature is corrected to the flow rate at the desired temperature based on the temperature measured by the temperature measuring means. -After specifying the propagation time characteristic, the temperature of the fluid to be measured can be calculated from the propagation time, so that low power consumption can be realized.

  Furthermore, even if there is no preset temperature-propagation time characteristic, the temperature-propagation time characteristic is learned according to the fluid to be measured, so it is possible to cope with multiple types of fluids to be measured. Low power consumption temperature correction can be realized.

  According to the flow rate measuring apparatus of the present invention, the temperature-propagation time characteristic of the fluid to be measured is specified based on the temperature measured by the temperature measuring means and the propagation time measured by the propagation time measuring means, and the fluid to be measured is determined only by the propagation time. Therefore, low power consumption can be realized.

Configuration diagram of a flow rate measuring device according to Embodiments 1, 2, and 3 of the present invention Operation flow diagram of flow rate measuring apparatus according to Embodiment 1 of the present invention Operation flow diagram of flow rate measuring device in embodiment 2 of the present invention Operation flow diagram of flow rate measuring device in embodiment 3 of the present invention Configuration diagram of conventional ultrasonic flowmeter Configuration diagram of conventional ultrasonic flowmeter

A first invention is provided with a first vibrator and a second vibrator that are provided in a fluid conduit and transmit / receive an ultrasonic signal, a temperature measuring means that measures a temperature of a fluid to be measured flowing in the fluid conduit, and the vibration Measured by the propagation time measuring means for driving the child and measuring the propagation time of transmission and reception of the ultrasonic signal, the control means for controlling the measurement timing of the temperature measuring means and the propagation time measuring means, and the propagation time measuring means The flow rate calculating means for calculating the flow rate from the propagation time of the ultrasonic signal and the fluid temperature to be measured are calculated from the propagation time measured by the propagation time measuring means, and the flow rate calculating means is calculated based on the calculated temperature. in the flow rate measuring apparatus having a flow rate correction means, a for temperature corrected flow rate to the flow rate at the desired temperature, the flow rate correction means, the temperature of the fluid to be measured - until propagation time characteristic can be specified, the temperature Based on the measured in the measuring means temperature to calculate the temperature of the fluid to be measured, the fluid to be measured temperature - after a certain propagation time characteristic of the fluid to be measured based on the timed propagation time by the propagation time measuring means Calculating a temperature.

  And first, until the temperature-propagation time characteristic (or temperature-sound speed characteristic) of the fluid to be measured can be specified, the temperature is corrected to the flow rate at a desired temperature based on the temperature measured by the temperature measuring means. However, after the temperature-propagation time characteristic of the fluid to be measured is specified, the temperature of the fluid to be measured can be calculated only from the propagation time, so that low power consumption can be realized. Furthermore, even if there is no preset temperature-propagation time characteristic, the temperature-propagation time characteristic is learned according to the fluid to be measured, so that it is possible to cope with a plurality of types of fluids to be measured. Accordingly, temperature correction with low power consumption can be realized for a plurality of types of fluids to be measured.

  In a second aspect based on the first aspect, the temperature measuring means periodically measures the temperature of the fluid to be measured, and the temperature-propagation time characteristic is specified and updated for each measurement by the temperature measuring means. Is. Since the temperature-propagation time characteristic of the fluid to be measured can be specified and updated again periodically, the temperature correction of the flow rate with higher accuracy than the first invention can be realized.

In a third aspect based on the first aspect, the temperature measuring means periodically measures the temperature of the fluid to be measured, and the measured temperature of the fluid to be measured last updated the temperature-propagation time characteristic. When the temperature is sometimes changed from the measured temperature by a predetermined value or more, the temperature-propagation time characteristic is specified and updated based on the temperature measured this time. When it is determined that there has been a temperature change, the temperature-propagation time characteristic of the fluid to be measured can be identified and updated again, so that a more accurate flow rate temperature correction can be realized than in the first invention.

  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.

(Embodiment 1)
FIG. 1 shows a configuration diagram of a flow rate measuring apparatus according to a first embodiment of the present invention. FIG. 2 is an operation flowchart of the flow rate measuring apparatus according to the first embodiment of the present invention.

  In FIG. 1, a first ultrasonic transducer 2 (first transducer) and a second ultrasonic transducer 3 (second transducer) that transmit and receive ultrasonic waves are disposed in the middle of a flow path 1. The temperature measuring unit 8 measures the temperature of the fluid to be measured flowing through the flow path 1 in accordance with an instruction from the control unit 7 (hereinafter, the temperature measured by the temperature measuring unit 8 is referred to as an actual temperature). The propagation time measuring unit 4 drives the first ultrasonic transducer 2 and the second ultrasonic transducer 3 in accordance with an instruction from the control unit 7 and determines the propagation time of the ultrasonic signal transmitted and received between the ultrasonic transducers. measure.

  The flow rate calculation means 5 calculates the flow rate flowing through the flow path 1 from the propagation time of the ultrasonic signal measured by the propagation time measurement means 4. The flow rate correction means 6 calculates the flow rate calculated by the flow rate calculation means 5 from the actual temperature of the fluid measured by the temperature measurement means 8 and the temperature of the fluid to be measured calculated from the propagation time measured by the propagation time measurement means 4. The temperature is corrected to a flow rate at a desired temperature. The control means 7 outputs an instruction for measuring the flow rate to the propagation time measuring means 4 and also outputs an instruction for measuring the actual temperature of the fluid to the temperature measuring means 8.

  The operation and action of the flow rate measuring apparatus configured as described above will be described below with reference to FIG.

  First, flow measurement starts in S001. When it is time to measure the flow rate in S002, the control means 7 outputs a flow measurement instruction to the propagation time measurement means 4. The propagation time measuring unit 4 is turned on by an instruction from the control unit 7 in S003, drives the first ultrasonic transducer 2 and the second ultrasonic transducer 3 in S004, and transmits and receives between both ultrasonic transducers in S005. Measure and output ultrasonic signal propagation time. In S006, the flow rate calculation means 5 calculates and outputs the flow rate flowing through the flow path 1 based on the propagation time output from the propagation time measurement means 4. The flow rate correcting means 6 calculates the sound velocity of the fluid to be measured from the propagation time output from the propagation time measuring means 4 in S007.

Here, if the velocity of sound of the fluid to be measured is v, the propagation time is t, and the distance between the first ultrasonic transducer 2 and the second ultrasonic transducer 3 is L,
v = L / t
The sound speed of the fluid to be measured can be calculated by the following equation.

  In step S008, the flow rate correction unit 6 determines whether the temperature-propagation time characteristic of the fluid to be measured has already been calculated and specified. If it is determined that the flow rate has been specified, the flow rate correction unit 6 calculates the temperature of the fluid to be measured from the propagation time from the temperature-propagation time characteristic already specified in S012. If it is determined in S008 that it has not been specified, the control means 7 instructs the temperature measuring means 8 to measure the actual temperature of the fluid to be measured in S009, and the temperature measuring means 8 measures the actual temperature of the fluid to be measured. The measurement result is output to the flow rate correction means 6.

In step S010, it is determined whether the actual temperature of the fluid to be measured is measured for the first time or the second time. In the second case, in S011, the temperature-sound velocity measurement and temperature-propagation time characteristics of the fluid to be measured are calculated and specified from two points (temperature, sound velocity) and (temperature, propagation time). In step S012, the temperature of the fluid to be measured is calculated from the propagation time from the temperature-propagation time characteristic already specified. When it is determined in S010 that it is the first time, the actual temperature measured in S013 is set as the temperature of the fluid to be measured. In step S014, the flow rate correction unit 6 performs temperature correction on the flow rate at the desired temperature based on the temperature calculated in step S012 or the temperature actually measured in steps S009 and S013. Then, returning to S002, the measurement of the propagation time is repeated at the next measurement timing.

  As described above, first, until the temperature-propagation time characteristic (or temperature-sound speed characteristic) of the fluid to be measured can be specified, the temperature is corrected to the flow rate at a desired temperature based on the temperature measured by the temperature measuring unit 8. However, after specifying the temperature-propagation time characteristic (or temperature-sound speed characteristic) of the fluid to be measured, the temperature of the fluid to be measured is calculated only from the propagation time measured by the propagation time measuring means 4. Therefore, low power consumption can be realized. Furthermore, it is possible to cope with a plurality of types of fluids to be measured by specifying and updating the temperature-propagation time characteristics according to the fluids to be measured. Therefore, temperature correction with low power consumption can be realized for a plurality of types of fluids to be measured.

(Embodiment 2)
FIG. 3 shows an operation flow diagram of the flow rate measuring apparatus according to the second embodiment of the present invention. The block diagram of the flow rate measuring device in the present embodiment is the same as that in FIG.

  1, the timing at which the control means 7 instructs the temperature measurement means 8 to measure the actual temperature of the fluid is different from that of the first embodiment. In the present embodiment, an instruction to measure the actual flow rate is output when the temperature-sonic velocity characteristic and the temperature-propagation time characteristic of the fluid to be measured cannot be specified. However, in this embodiment, in addition to the case of the first embodiment, an instruction to measure the actual temperature is also output when it is determined that a predetermined time has elapsed since the actual temperature of the fluid to be measured was measured last time. That is, the temperature measuring means 8 periodically measures the actual temperature of the fluid to be measured.

  The operation and action of the ultrasonic flowmeter configured as described above will be described below with reference to FIG.

  First, flow measurement starts in S001. When it is time to measure the flow rate in S002, the control means 7 outputs a flow measurement instruction to the propagation time measurement means 4. The propagation time measuring unit 4 is turned on by an instruction from the control unit 7 in S003, drives the first ultrasonic transducer 2 and the second ultrasonic transducer 3 in S004, and transmits and receives between both ultrasonic transducers in S005. Measure and output ultrasonic signal propagation time. In S006, the flow rate calculation means 5 calculates and outputs the flow rate flowing through the flow path 1 based on the propagation time output from the propagation time measurement means 4. The flow rate correcting means 6 calculates the sound velocity of the fluid to be measured from the propagation time output from the propagation time measuring means 4 in S007.

Here, if the velocity of sound of the fluid to be measured is v, the propagation time is t, and the distance between the first ultrasonic transducer 2 and the second ultrasonic transducer 3 is L,
v = L / t
Thus, the sound speed of the fluid to be measured can be calculated.

  In step S008, the flow rate correction unit 6 determines whether the temperature-propagation time characteristic of the fluid to be measured has already been calculated and specified. If it is determined that it has been specified, it is further determined in S015 whether or not a certain time has elapsed since the previous actual temperature measurement of the fluid to be measured. If it is determined that the time of S015 has not yet elapsed, the flow rate correction means 6 calculates the temperature of the fluid to be measured from the propagation time from the temperature-propagation time characteristics already specified in S012. If it is determined in S008 that it has not been specified yet, or if it is determined that the time of S015 has elapsed, the control means 7 instructs the temperature measuring means 8 to measure the actual temperature of the fluid to be measured in S009. The temperature measuring unit 8 measures the actual temperature of the fluid to be measured and outputs the measurement result to the flow rate correcting unit 6.

  In S016, it is determined whether or not the actual temperature of the fluid to be measured has been measured twice or more. In the case of the second time or more, in S017, the temperature-sound velocity measurement and temperature-propagation time characteristics of the fluid to be measured are calculated and specified from two or more points (temperature, sound velocity) and (temperature, propagation time). If there is already specified temperature-sound speed measurement or temperature-propagation time characteristic, update to newly calculated temperature-sound speed measurement or temperature-propagation time characteristic to correct temperature-sound measurement or temperature-propagation time characteristic Can continue.

  Then, the temperature of the fluid to be measured is calculated from the propagation time from the temperature-propagation time characteristic already specified in S012. When it is determined in S016 that it is less than twice, the actual temperature measured by the temperature measuring means 8 in S013 is set as the temperature of the fluid to be measured. In S014, the flow rate correction means 6 performs temperature correction on the flow rate at the desired temperature based on the temperature calculated in S012 or the temperature actually measured in S009 and S013. Then, returning to S002, the measurement of the propagation time is repeated at the next measurement timing.

  As described above, until the temperature-propagation time characteristic (or temperature-sound speed characteristic) of the fluid to be measured can be specified at first, the temperature is corrected to the flow rate at a desired temperature based on the temperature measured by the temperature measuring unit 8. However, after the temperature-propagation time characteristic (or temperature-sound speed characteristic) of the fluid to be measured is specified, the temperature of the fluid to be measured can be calculated only from the propagation time, thus reducing power consumption. Can be realized.

  Furthermore, since temperature-propagation time characteristics (or temperature-sound speed characteristics) are learned according to the fluid to be measured, it is possible to cope with a plurality of types of fluids to be measured. Accordingly, temperature correction with low power consumption can be realized for a plurality of types of fluids to be measured.

  Further, when a predetermined time has elapsed since the previous actual temperature measurement, the temperature measuring means 8 remeasures the actual temperature of the fluid to be measured, and periodically measures the temperature-propagation time characteristic (or temperature-sound speed characteristic) of the fluid to be measured. ) Can be identified and updated again.

(Embodiment 3)
FIG. 4 shows an operation flow diagram of the flow rate measuring device according to the third embodiment of the present invention. The configuration diagram of the flow rate measuring device in the present embodiment is the same as that in FIG.

  1, the timing at which the control means 7 instructs the temperature measurement means 8 to measure the actual temperature of the fluid is different from that of the first embodiment. In the first embodiment, an instruction to measure the actual flow rate is output when the temperature-sonic velocity characteristic and the temperature-propagation time characteristic of the fluid to be measured cannot be specified. However, in the present embodiment, in addition to the case of the first embodiment, an instruction to measure the actual temperature is also output when it is determined that the temperature of the fluid to be measured has changed by a certain value or more since the actual temperature was measured last time. To do.

  The operation and action of the ultrasonic flowmeter configured as described above will be described below with reference to FIG.

  First, flow measurement starts in S001. When it is time to measure the flow rate in S002, the control means 7 outputs a flow measurement instruction to the propagation time measurement means 4. The propagation time measuring unit 4 is turned on by an instruction from the control unit 7 in S003, drives the first ultrasonic transducer 2 and the second ultrasonic transducer 3 in S004, and transmits and receives between both ultrasonic transducers in S005. Measure and output ultrasonic signal propagation time. In S006, the flow rate calculation means 5 calculates and outputs the flow rate flowing through the flow path 1 based on the propagation time output from the propagation time measurement means 4. The flow rate correction means 6 calculates the sound velocity of the fluid to be measured from the propagation time output from the propagation time measurement means 4 in S007.

Here, if the velocity of sound of the fluid to be measured is v, the propagation time is t, and the distance between the first ultrasonic transducer 2 and the second ultrasonic transducer 3 is L,
v = L / t
Thus, the sound speed of the fluid to be measured can be calculated.

  In step S008, the flow rate correction unit 6 determines whether the temperature-propagation time characteristic of the fluid to be measured has already been calculated and specified. If it is determined that it has been specified, the temperature of the fluid to be measured is calculated from the propagation time from the temperature-propagation time characteristic already specified in S012. Then, in S018, it is determined whether or not the temperature change is more than a certain value from the actual temperature of the fluid to be measured previously measured. If it is determined that the temperature change is less than a certain value, the process proceeds to S014. If it is determined in S008 that it has not been specified yet, or if it is determined in S018 that the temperature change has exceeded a certain value, the control means 7 instructs the temperature measurement means 8 to measure the actual temperature of the fluid to be measured in S009. The temperature measuring unit 8 measures the actual temperature of the fluid to be measured and outputs the measurement result to the flow rate correcting unit 6.

  In S016, it is determined whether or not the actual temperature of the fluid to be measured has been measured twice or more. In the case of the second time or more, in S017, the temperature-sound velocity measurement and temperature-propagation time characteristics of the fluid to be measured are calculated and specified from two or more points (temperature, sound velocity) and (temperature, propagation time). If there is already specified temperature-sound speed measurement or temperature-propagation time characteristic, update to newly calculated temperature-sound speed measurement or temperature-propagation time characteristic to correct temperature-sound measurement or temperature-propagation time characteristic Can continue. In step S019, the temperature of the fluid to be measured is calculated from the propagation time from the temperature-propagation time characteristic already specified. When it is determined in S016 that it is less than twice, the actual temperature measured by the temperature measuring means 8 in S013 is set as the temperature of the fluid to be measured.

  In step S014, the flow rate correction unit 6 performs temperature correction on the flow rate at the desired temperature based on the temperature calculated in step S012 or S019 or the temperature actually measured in steps S009 and S013. Then, returning to S002, the measurement of the propagation time is repeated at the next measurement timing.

  As described above, until the temperature-propagation time characteristic (or temperature-sound speed characteristic) of the fluid to be measured can be specified at first, the temperature is corrected to the flow rate at a desired temperature based on the temperature measured by the temperature measuring unit 8. However, after the temperature-propagation time characteristic (or temperature-sound speed characteristic) of the fluid to be measured is specified, the temperature of the fluid to be measured can be calculated only from the propagation time, thus reducing power consumption. Can be realized. Furthermore, since temperature-propagation time characteristics (or temperature-sound speed characteristics) are learned according to the fluid to be measured, it is possible to cope with a plurality of types of fluids to be measured. Accordingly, temperature correction with low power consumption can be realized for a plurality of types of fluids to be measured.

  Further, when it is determined that the temperature of the fluid to be measured has changed by a certain value or more from the actual temperature measured last time, the actual temperature of the fluid to be measured is measured again, and the temperature-propagation time characteristic (or temperature- (Sonic velocity characteristics) can be re-learned and corrected, so that the temperature correction of the flow rate with higher accuracy than that of claim 1 can be realized.

  As described above, the flow rate measuring device according to the present invention is initially set to a desired temperature based on the temperature measured by the temperature measuring means until the temperature-sonic speed characteristic or the temperature-propagation time characteristic of the fluid to be measured can be specified. However, after the temperature-sound velocity characteristic or temperature-propagation time characteristic of the fluid to be measured is specified, the temperature of the fluid to be measured can be calculated from only the propagation time. Since low power consumption can be realized, it is possible to realize a flow measuring device with very low power consumption and high versatility, and it can also be applied to applications such as a flow measuring standard device, a gas meter, and a water meter.

1 channel 2 first ultrasonic transducer (first transducer)
3 Second ultrasonic transducer (second transducer)
4 Propagation time measuring means 5 Flow rate calculating means 6 Flow rate correcting means 7 Control means 8 Temperature measuring means

Claims (3)

A first vibrator and a second vibrator that are provided in the fluid conduit and transmit and receive ultrasonic signals;
Temperature measuring means for measuring the temperature of the fluid to be measured flowing in the fluid conduit;
A propagation time measuring means for driving the vibrator and measuring the propagation time of transmission / reception of an ultrasonic signal;
Control means for controlling the measurement timing of the temperature measuring means and the propagation time measuring means;
A flow rate calculating means for calculating a flow rate from the propagation time of the ultrasonic signal measured by the propagation time measuring means;
A flow rate correction for calculating a fluid temperature to be measured from the propagation time measured by the propagation time measuring unit, and correcting the flow rate calculated by the flow rate calculating unit to a flow rate at a desired temperature based on the calculated temperature. Means,
In the flow measuring device with
The flow rate correction unit calculates the temperature of the fluid to be measured based on the temperature measured by the temperature measuring unit until the temperature-propagation time property of the fluid to be measured can be specified, and the temperature-propagation time property of the fluid to be measured. After the identification , calculating the temperature of the fluid to be measured based on the propagation time measured by the propagation time measuring means ,
A flow measuring device characterized by The flow rate measuring apparatus according to claim 1, wherein the temperature measuring unit periodically measures the temperature of the fluid to be measured, and the temperature-propagation time characteristic is specified and updated for each measurement of the temperature measuring unit. The temperature measuring means periodically measures the temperature of the fluid to be measured, and when the measured temperature of the fluid to be measured has changed more than a predetermined value from the temperature measured when the temperature-propagation time characteristic was updated last time, The flow rate measuring device according to claim 1, wherein the temperature-propagation time characteristic is specified and updated based on the temperature measured this time.