JP3653829B2 - Anemometer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an anemometer that measures a flow velocity of water, air, or the like.
[0002]
[Prior art]
  The conventional anemometer is shown in the figure13As shown in FIG. 2, the two pairs of ultrasonic probes 2, 3, 4, 5 installed opposite to each other in the pipe 1 through which the fluid flows are super-directional so as to be in the forward and reverse directions with respect to the direction in which the fluid flows. The sound wave is propagated, the propagation time from the ultrasonic probe 2 to 4 is measured by the counter 8, the propagation time from 3 to 5 is measured by the counter 9, and the fluid flow velocity is calculated by the calculation unit 7 based on the propagation time. Is configured to ask for.
[0003]
  Here, the velocity meter has t1 as the propagation time of the ultrasonic wave in the direction in which the fluid flows, and t2 as the propagation time of the ultrasonic wave in the direction opposite to the direction in which the fluid flows.
      t1 = L / (C + v), t2 = L / (C−v)
Than this,
      1 / t1-1 / t2 = 2v / L
      v = L (t2−t1) / 2 (t1 · t2) (1)
The fluid flow velocity was obtained from t1 and t2.
[0004]
[Problems to be solved by the invention]
  However, in the above-described conventional configuration, it is difficult to accurately obtain the ultrasonic propagation time difference t1-t2 (hereinafter referred to as Δt) when the fluid velocity is much slower than the sound velocity. For example, when L = 40 mm, C = 340 m / s, and v = 1 mm / s,
      t1 = 1177.6467128... μs,
      t2 = 117.64774048... μs,
      Δt = 692 ... ps,
It becomes the value. If this value is to be measured with an accuracy of about 10%, two 24-bit counters having a clock of 100 Ghz are required in the forward and reverse directions of the flow. For this reason, the flow velocity is obtained without reducing the accuracy with a low clock by calculating the sum of the ultrasonic wave propagation times by repeating the measurement not only once but several hundred to several tens of thousands of times.
[0005]
  However, if the measurement is repeated many times in this manner and the two counters are moved and measured, a large amount of power is required to obtain the measurement result. For this reason, this method could not be adopted particularly in an anemometer that must operate for several years using a battery as a power source. In addition, since it takes several seconds to several tens of seconds to obtain the measurement result, there is a problem that the fluid cannot be used for a measurement in which the measurement result is abrupt, such as a fluid with a large flow rate fluctuation.
[0006]
  SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and aims to realize a current meter that can measure a flow velocity with high accuracy, instantaneously and with low power consumption, and can operate for several years using a battery as a power source.
[0007]
[Means for Solving the Problems]
  In the anemometer of the present invention, the pipe through which the fluid flowsFrom upstreamA first reception ultrasonic probe, a transmission ultrasonic probe, and a second reception ultrasonic probe, which are sequentially provided;An oscillation circuit that outputs an oscillation signal to the transmission ultrasonic probe by an oscillation start signal, and a first measurement that starts measurement by an oscillation start signal of the oscillation circuit and ends measurement by the output of the second reception ultrasonic probe And a second measurement unit that starts measurement by the second reception ultrasonic probe and ends measurement by the first reception ultrasonic probe, the first measurement unit and the second measurement unit The flow velocity is obtained from the output ofing.
[0008]
  According to the present invention, even if the same direction as the flow and the opposite direction are measured at the same time, no interference occurs and the flow velocity can be measured in a short operation time, so that the power consumption is reduced.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
  In order to achieve the above object, the present inventionA first reception ultrasonic probe, a transmission ultrasonic probe, a second reception ultrasonic probe, and a first reception ultrasonic probe connected to each of the first and second reception ultrasonic probes, which are sequentially provided in a conduit through which a fluid flows. The measurement unit and the second measurement unit, a calculation unit that receives time information from the first measurement unit and the second measurement unit, obtains a flow velocity, and receives a signal from the calculation unit and oscillates in the transmission ultrasonic probe And an oscillation circuit that outputs a signal.
[0010]
  Also, ultrasonic probes are installed at equal intervals in the order of reception, transmission, and reception, measurement is started by an oscillation start signal from the calculation unit, and the received ultrasonic probe output is installed upstream or downstream of the fluid flow. The measurement unit 1 that ends the measurement and the measurement unit 2 that starts the measurement by the reception ultrasonic probe installed on the downstream side of the flow and ends the measurement by the reception ultrasonic probe installed on the upstream side of the flow are provided. .
[0011]
  An ultrasonic probe is installed in the direction of fluid flow in the order of reception, transmission, and reception, and the two receptions are performed.TrustThe phase inversion circuit is provided at the output on one side of the ultrasonic probe for use.
[0012]
  A U-shaped measuring line having a U-shaped shape through which a fluid flows, and having an inlet in a lateral direction of the U-shaped end portion and an outlet in a lateral direction of the U-shaped upper portion at the other end; A transmission ultrasonic probe that emits ultrasonic waves from the U-shaped bottom position toward the inlet and outlet of the U-shaped measurement pipe, and a reception ultrasonic probe 1 provided at each of the inlet and outlet of the U-shaped measurement pipe A reception ultrasonic probe 2, an oscillation circuit that simultaneously outputs an oscillation signal to the transmission ultrasonic probe, and a measurement unit that measures a detection time difference between ultrasonic waves detected by the reception ultrasonic probe 1 and the reception ultrasonic probe 2. The configuration is provided.
[0013]
  A U-shaped measuring line having a U-shaped shape through which a fluid flows, and having an inlet in a lateral direction of the U-shaped end portion and an outlet in a lateral direction of the U-shaped upper portion at the other end; A transmitter ultrasonic probe that emits ultrasonic waves from the U-shaped bottom position toward the inlet and outlet of the U-shaped measurement pipeline, and installed across both the inlet and outlet pipelines of the U-shaped measurement pipeline The reception ultrasonic probe, an oscillation circuit that outputs an oscillation signal to the transmission ultrasonic probe, and a measurement unit that measures a difference in detection time of ultrasonic waves detected by the reception ultrasonic probe are provided.
[0014]
  A U-shaped measuring pipe having a U-shape in the shape of a pipe through which the fluid flows, having an inlet in the lateral direction of the U-shaped end and an outlet in the lateral direction of the U-shaped upper position at the other end; A transmitting ultrasonic probe that emits ultrasonic waves from the U-shaped bottom position toward the inlet and outlet of the U-shaped measurement pipe, and a receiving ultrasonic probe provided at the inlet and outlet of the U-shaped measuring pipe, An oscillation circuit that simultaneously outputs an oscillation signal to the transmission ultrasonic probe, a measurement unit that measures a detection time difference between ultrasonic waves detected by the reception ultrasonic probe, and a calculation unit that obtains the flow velocity of the fluid based on the detection time difference. And a U-shaped measuring pipe having an M-shaped U-shaped measuring pipe.
[0015]
  In addition, a pipe line through which the fluid flows, a transmission ultrasonic probe that simultaneously emits ultrasonic waves in the direction of fluid flow and the opposite direction, an oscillation circuit that outputs an oscillation output to the ultrasonic probe, and the ultrasonic waves are received. A reception ultrasonic probe, a measurement unit that operates according to an output of the reception ultrasonic probe, a pulse width measurement device that measures an output time width of the reception probe, information obtained from the measurement unit, and a pulse width measurement device When the output of the pulse width measuring instrument exceeds a certain value, the flow rate is determined by subtracting the value preset in the calculation unit from the pulse width as the ultrasonic detection time difference. It is as composition which asks for.
[0016]
  In addition, a pipe line through which the fluid flows, a transmission ultrasonic probe that simultaneously emits ultrasonic waves in the direction of fluid flow and in the opposite direction, an oscillation circuit that outputs an oscillation output to the ultrasonic probe, and reception that receives ultrasonic waves An ultrasonic probe, a measurement unit that operates according to an output of the reception ultrasonic probe and an output of the calculation unit, a pulse width measuring device that measures an output time width of the reception probe, information obtained from the measurement unit, and the pulse width When the output of the pulse width measuring device exceeds a certain value, the pulse width measured by stopping the oscillation of the ultrasonic wave in the direction of the fluid flow is obtained. The flow rate is obtained by using the value obtained by subtracting the output from the pulse width measuring device as the ultrasonic detection time difference.
[0017]
  Also, a conduit through which the fluid flows, a transmission ultrasonic probe that simultaneously emits ultrasonic waves in the direction of fluid flow and in the opposite direction, an oscillation circuit that outputs an oscillation output to the ultrasonic probe, an upstream direction and a downstream direction of the flow A receiving ultrasonic probe that receives ultrasonic waves from a direction, a measuring unit that operates according to an output of a calculation unit and an output of the receiving ultrasonic probe, and a pulse width measurement that measures an output time width of the receiving probe And when the output of the pulse width measuring device is less than one constant value, the output of the pulse width measuring device. Is used to measure the flow velocity of the fluid.
[0018]
  The present invention has the above configuration.Since the ultrasonic probe is installed in the order of reception, transmission, and reception from the direction of fluid flow, a single transmission ultrasonic probe can simultaneously output in the forward and reverse directions of the flow and perform simultaneous measurement..
[0019]
  Also, ultrasonic probes are installed at equal intervals in the order of reception, transmission, and reception, measurement is started by an oscillation start signal from the calculation unit, and the received ultrasonic probe output is installed upstream or downstream of the fluid flow. The measurement unit 1 that ends the measurement and the measurement unit 2 that starts the measurement by the reception ultrasonic probe installed on the downstream side of the flow and ends the measurement by the reception ultrasonic probe installed on the upstream side of the flow are provided. Therefore, the measurement of t1 or t2 is separated from the measurement unit 1, and the measurement of Δt is separated from the measurement unit 2.
[0020]
  In addition, since the ultrasonic probe is installed in the direction of fluid flow in the order of reception, transmission, and reception, and the phase inversion circuit is provided on the output on one side of the two diagnostic ultrasound probes, The downstream measurement unit input initial phase is aligned.
[0021]
  A U-shaped measuring line having a U-shaped shape through which a fluid flows, and having an inlet in a lateral direction of the U-shaped end portion and an outlet in a lateral direction of the U-shaped upper portion at the other end; A transmission ultrasonic probe that emits ultrasonic waves from the U-shaped bottom position toward the inlet and outlet of the U-shaped measurement pipe, and a reception ultrasonic probe 1 provided at each of the inlet and outlet of the U-shaped measurement pipe Since the receiving ultrasonic probe 2 is provided, an ultrasonic output can be simultaneously output in the direction opposite to the same direction as the flow by one transmission ultrasonic probe.
[0022]
  A U-shaped measuring line having a U-shaped shape through which a fluid flows, and having an inlet in a lateral direction of the U-shaped end portion and an outlet in a lateral direction of the U-shaped upper portion at the other end; A transmitter ultrasonic probe that emits ultrasonic waves from the U-shaped bottom position toward the inlet and outlet of the U-shaped measurement pipeline, and installed across both the inlet and outlet pipelines of the U-shaped measurement pipeline Since the receiving ultrasonic probe is provided, an ultrasonic reception signal in the same direction as the flow and in the opposite direction is handled by one reception path.
[0023]
  A U-shaped measuring pipe having a U-shape in the shape of a pipe through which the fluid flows, having an inlet in the lateral direction of the U-shaped end and an outlet in the lateral direction of the U-shaped upper position at the other end; A transmitting ultrasonic probe that emits ultrasonic waves from the U-shaped bottom position toward the inlet and outlet of the U-shaped measurement pipe, and a receiving ultrasonic probe provided at the inlet and outlet of the U-shaped measuring pipe, Since the U-shaped pipe has a configuration in which the direction of the pipe is further changed to the inlet side and the outlet side of the U-shaped pipe, and is configured as an M-shaped U-shaped measuring pipe. Since the conditions of the front and rear flow paths are the same, the fluid flow is the same in the measurement path in the same direction as the flow and in the opposite direction.
[0024]
  In addition, the flow path of the fluid, the transmission ultrasonic probe that simultaneously emits ultrasonic waves in the direction of fluid flow and the opposite direction, the reception ultrasonic probe that receives the ultrasonic waves, and the output time width of the reception probe When the pulse width measuring device to be measured and the output of the pulse width measuring device exceed one constant value, the flow rate is obtained by using a value obtained by subtracting the value preset in the calculation unit from the pulse width as an ultrasonic detection time difference. Since the configuration is such that the flow of the fluid and the timing of receiving ultrasonic waves with the reception ultrasonic probe in the forward direction and the reverse direction are substantially the same, and the received signals overlap and the pulse width becomes wide, the one direction set in the calculation unit An accurate ultrasonic detection time difference is obtained by using, as the ultrasonic detection time difference, a value obtained by subtracting the received pulse width data when only ultrasonic waves are received.
[0025]
  In addition, a pipe line through which the fluid flows, a transmission ultrasonic probe that simultaneously emits ultrasonic waves in the direction of fluid flow and in the opposite direction, an oscillation circuit that outputs an oscillation output to the ultrasonic probe, and reception that receives ultrasonic waves An ultrasonic probe, a measurement unit that operates according to an output of the reception ultrasonic probe and an output of the calculation unit, a pulse width measuring device that measures an output time width of the reception probe, information obtained from the measurement unit, and the pulse width It consists of a calculation unit that obtains the flow velocity according to the output of the measuring device. When the output of the pulse width measuring device exceeds a certain value, the measurement is performed by stopping the oscillation of the ultrasonic wave in the direction of the fluid flow, and the obtained pulse. Since the flow rate is calculated using the difference between the width and the output of the pulse width measuring device as the ultrasonic detection time difference, the ultrasonic wave is received by the receiving ultrasonic probe in the forward and reverse directions of the fluid flow. Timing is substantially the same, to obtain an accurate ultrasound detection time difference by subtracting the pulse width corresponding to one side of the ultrasonic wave reception time when the received signal is wider overlapping pulse width.
[0026]
  Also, a conduit through which the fluid flows, a transmission ultrasonic probe that simultaneously emits ultrasonic waves in the direction of fluid flow and in the opposite direction, an oscillation circuit that outputs an oscillation output to the ultrasonic probe, an upstream direction and a downstream direction of the flow A receiving ultrasonic probe that receives ultrasonic waves from a direction, a measuring unit that operates according to an output of a calculation unit and an output of the receiving ultrasonic probe, and a pulse width measurement that measures an output time width of the receiving probe And when the output of the pulse width measuring device is less than one constant value, the output of the pulse width measuring device. Since the flow velocity of the fluid is measured using the difference in ultrasonic detection time, the timing of receiving ultrasonic waves with the receiving ultrasonic probe in the forward and reverse directions is almost the same as the flow of the fluid. Even when signals are overlapped and received at a timing that cancels out the overlapping parts of the overlapping phases, the accurate ultrasonic detection time difference can be obtained by using pulse width data as the ultrasonic detection time difference. I can do it.
[0027]
  Hereinafter, a first embodiment of the present invention will be described with reference to FIG. In the figure, reference numeral 1 denotes a pipe through which a fluid flows at a speed of v. Transmission ultrasonic probes 2 and 3 installed in the same direction as the flow of the fluid in the pipe 1 and transmission ultrasonic probes 2 and 3 Receiving ultrasonic probes 4 and 5 installed facing each other at a distance of L, an oscillation circuit 6 for sending an oscillation signal to the transmitting ultrasonic probes 2 and 3, and an arithmetic unit for controlling the oscillation of the oscillation circuit 6 7, a counter 8 that starts initialization and time measurement by an oscillation start signal from the calculation unit 7 to the oscillation circuit 6, and ends time measurement by the output of the reception ultrasonic probe 4, and a signal from the calculation unit 7 to the oscillation circuit 6. A counter 9 that starts initialization and time measurement by the oscillation start signal and ends time measurement by the output of the reception ultrasonic probe 5, and a shielding plate 10 that shields the ultrasonic probes 2, 4 and the ultrasonic probes 3, 5 are provided. Prepare And it has a formation.
[0028]
  In this configuration, the calculation unit 7 sends an oscillation start signal to the oscillation circuit 6 to simultaneously output ultrasonic waves from the transmission ultrasonic probes 2 and 3. At the same time, the counter 8 and the counter 9 are initialized and the counting is started. Since the ultrasonic wave emitted from the transmission ultrasonic probe 2 is shielded by the shielding plate 10, it is not received by the reception ultrasonic probe 5 and is in the same direction as the flow of the fluid. The process proceeds to 4 and is received after t1 = {L / (C + v)} time. By the output of the reception ultrasonic probe 4, the counter 8 finishes counting and passes the count corresponding to t <b> 1 to the calculation unit 7. In addition, since the ultrasonic wave emitted from the transmission ultrasonic probe 3 is shielded by the shielding plate 10, it is not received by the reception ultrasonic probe 4, and is in a direction opposite to the flow of the fluid. The process proceeds to the reception ultrasonic probe 5 and is received after t2 = {L / (C−v)} time. By the output of the reception ultrasonic probe 5, the counter 9 finishes counting and passes the count number corresponding to t2 to the calculation unit 7. The calculation unit 7 calculates v = L (t1-t2) / 2 (t1 * t2) based on the counts received from the counters 8 and 9 to obtain the fluid velocity v. In addition, since each ultrasonic probe is configured such that the distance to the end of the shielding plate 10 is S1> L and S2> L, even if an ultrasonic wave wraps around, the ultrasonic wave received first by the receiving ultrasonic probe The sound wave is an ultrasonic wave output from the opposing transmission ultrasonic probe.
[0029]
  According to this embodiment, since the ultrasonic transmission time in the same direction as the fluid flow and in the opposite direction can be measured simultaneously, the measurement can be performed quickly. Accordingly, the time for operating the counters 8 and 9 and the clock for operating the counter can be shortened, so that measurement can be performed with low power consumption.
[0030]
  Next, FIG. 2 shows a second embodiment of the present invention. 1 denote the same functions as those of the invention shown in FIG. 1, and a description thereof will be omitted.
[0031]
  A reception ultrasonic probe 5, a transmission ultrasonic probe 11, and a reception ultrasonic probe 4 are installed in the pipe line 1 through which the fluid flows by a distance L in the fluid flow direction. The transmission ultrasonic probe 11 receives the output of the oscillation circuit 6 oscillated by the oscillation start signal from the calculation unit 7 and outputs ultrasonic waves simultaneously in the direction opposite to the direction of fluid flow. According to this configuration, it is possible to transmit an ultrasonic output in the direction opposite to the direction of fluid flow with one transmission ultrasonic probe at the same time without worrying about interference.
[0032]
  Next, a third embodiment of the present invention shown in FIG. 3 will be described. 1 and 2 function in the same manner as the invention shown in FIG.
[0033]
  The counter 13 performs initial setting based on the output of the reception ultrasonic probe 4 and starts counting. Thereafter, the counter 13 ends counting by the output of the phase inverting circuit 12 and outputs count information to the calculation unit 7. This time relation is shown in FIG. That is, the counter 13 counts the ultrasonic propagation time difference Δt time in the same direction as the fluid flow direction and in the opposite direction. According to the configuration of this embodiment, it is only necessary to perform Δt measured by the counter 13 in order to perform high-precision measurement, and even if the clock of the counter 8 is reduced to a ratio of the sound speed C and the flow velocity v. There is almost no influence on the accuracy of calculation. Therefore, it is not necessary to move two high-speed counters for a long time, and power consumption can be kept low.
[0034]
  Next, a fourth embodiment of the present invention shown in FIG. 5 will be described. 1 and 2 and 3 function in the same manner as the invention shown in FIG.
[0035]
  Reference numeral 12 denotes a phase inversion circuit which shifts the phase of the input waveform by 180 degrees and outputs it to the counter 13. Since the output signal of the reception ultrasonic probe 5 is inverted by the phase inversion circuit 12, the output of the transmission ultrasonic probe 11 is an ultrasonic wave that is 180 degrees out of phase in the same direction as the fluid flow and in the opposite direction. Output is possible. For this reason, the transmission ultrasonic probe 11 can use both-side output in the vibration direction, and efficiently flows ultrasonic waves of the same intensity as compared with the case where the output is reflected and output in both directions with the same phase. Therefore, there is no need for correction of the reception level, reflection plate, etc., and there is an effect that an accurate current meter can be realized with a simple configuration.
[0036]
  Next, a fifth embodiment of the present invention shown in FIG. 6 will be described. 1, 2, 3, and 4 have the same functions as those of the invention shown in FIG.
[0037]
  Transmitting ultrasonic probe 17, transmitting ultrasonic probe 18, and measuring U-shaped conduit 15 inlet and outlet, which are substantially equal to the cross-sectional area of measuring U-shaped conduit 15 installed at the bottom of the U-shape of measuring U-shaped conduit 15. In response to the oscillation start signal from the reception ultrasonic probe 19, the reception ultrasonic probe 20, and the calculation unit 7, the transmission ultrasonic probe 17 and the transmission ultrasonic wave are approximately equal to the cross-sectional area of the U-shaped pipe line 15 installed in each. Counting is started by the oscillation circuit 6 output to the probe 18 and the oscillation start signal from the calculation unit 7, the counter 8 is stopped by the output of the reception ultrasonic probe 19, and the oscillation start signal from the calculation unit 7 is counted. The counter 9 that stops counting by the output of the reception ultrasonic probe 20 and the calculation of the output of both the counter 8 and the counter 9 in the pipeline It is adapted to measure the speed. In this configuration, the transmitting and receiving ultrasonic probes are approximately equal in size to the cross-sectional area of the pipe, so that the entire radial direction of the pipe can be scanned, and stable ultrasonic propagation with high reproducibility can be performed. And accurate flow rateTotalThe fruitPresentThere is an effect that can be done. In addition, since the shape of the pipe is U-shaped in the measurement portion in this way, an ultrasonic probe approximately equal to the cross-sectional area of the pipe can be attached without blocking the pipe.
[0038]
  Next, a sixth embodiment of the present invention shown in FIG. 7 will be described. 1 to 6 have the same functions as those of the invention shown in FIG.
[0039]
  A transmission ultrasonic probe 21 approximately equal to the bottom area of the measurement U-shaped conduit 15 installed at the bottom of the U-shape of the measurement U-shaped conduit 15, and U installed at the entrance and the outlet of the measurement U-shaped conduit 15, respectively. A reception ultrasonic probe 19 and a reception ultrasonic probe 20 that are substantially equal to the cross-sectional area of the pipe line 15; an oscillation circuit 6 that oscillates upon receiving an oscillation start signal from the calculation unit 7 and outputs the oscillation start signal to the transmission ultrasonic probe 21; The counting is started by the oscillation start signal from the unit 7 and stopped by the output of the reception ultrasonic probe 19, and the count is started by the oscillation start signal from the calculation unit 7, and the output of the reception ultrasonic probe 20 is output. The counter 9 which stops counting by the above-mentioned method, and the flow velocity in the pipe line is measured by calculation from both outputs of the counter 8 and the counter 9.
[0040]
  In this configuration, since the transmission ultrasonic probe has a size substantially equal to the bottom area of the pipe line, transmission of ultrasonic waves in the upstream direction and the downstream direction can be performed by one ultrasonic probe. In addition, it is possible to scan the entire radial direction of the pipe line, to perform stable ultrasonic propagation with high reproducibility, and to obtain an accurate flow velocity diameter.
[0041]
  Next, a seventh embodiment of the present invention shown in FIG. 8 will be described. 1 to 7 have the same functions as those of the invention shown in FIG. 1 and will not be described in detail.
[0042]
  A transmission ultrasonic probe 21 approximately equal to the cross-sectional area of the measurement U-shaped conduit 15 installed at the bottom portion of the U-shape of the measurement U-shaped conduit 15, and both the entrance and exit at the top of the measurement U-shaped conduit 15. The reception ultrasonic probe 22 installed in this way, the oscillation circuit 6 that oscillates in response to the oscillation start signal from the calculation unit 7, and outputs to the transmission ultrasonic probe 21, and starts counting by the oscillation start signal from the calculation unit 7. Then, the counter 8 that stops counting by the output of the reception ultrasonic probe 22 and outputs the count information to the calculation unit 7 starts counting by the output of the reception ultrasonic probe 22, and outputs the next reception ultrasonic probe 22. The counter 23 stops counting and outputs count information to the calculation unit 7.
[0043]
  With this configuration, in this configuration, the size of the transmission ultrasonic probe is approximately equal to the bottom area of the pipe line, so that it is possible to transmit ultrasonic waves in the upstream direction and the downstream direction with one ultrasonic probe. For this reason, since an ultrasonic wave having the same intensity can be transmitted in the upstream, downstream, and both directions without requiring a special circuit, an inexpensive, stable and highly accurate current meter can be provided. In addition, the reception ultrasonic probe can be commonly used for the forward direction and the reverse direction of the flow. For this reason, the receiving circuit uses the same circuit for receiving in the upstream direction and receiving in the downstream direction, so that variations in the elements and variations in the receiving circuit can be reduced. A good current meter can be provided.
[0044]
  Next, an eighth embodiment of the present invention shown in FIG. 9 will be described. 1 to 8 have the same functions as those of the invention shown in FIG. 1 and will not be described in detail.
[0045]
  The flow direction of both the inlet side and the outlet side of the measurement U-shaped pipe line 15 is changed to have a conversion pipe line 24 that is an M-shaped pipe line, and is installed at the bottom of the U-shape of the measurement U-shaped pipe line 15. From the transmission ultrasonic probe 21 substantially equal to the cross-sectional area of the measurement U-shaped pipe line 15, the reception ultrasonic probe 22 installed on the upper part of the measurement U-shaped pipe line 15 so as to cover both the entrance and the outlet, and the calculation unit 7 The oscillation circuit 6 that oscillates in response to the oscillation start signal and outputs it to the transmission ultrasonic probe 21 and the oscillation start signal from the calculation unit 7 starts counting, stops the count by the output of the reception ultrasonic probe 22, and count information Is started by the output of the counter 8 and the reception ultrasonic probe 22, is stopped by the output of the next reception ultrasonic probe 22, and the count information is output to the calculation unit 7. And a that counter 23. With this configuration, first, the fluid that has entered from the front rectifying conduit 14 changes its direction by 180 degrees and enters the measurement U-shaped conduit 15. Further, the direction of the measurement U-shaped line 15 is changed by 180 degrees, and the direction is further changed by 180 degrees to enter the rear rectifying line 16. As can be seen from this, the flow of fluid, the forward ultrasonic U-shaped measuring pipe, and the backward acoustic U-shaped U-shaped pipe before and after the portion of the U-shaped U-shaped measuring pipe 15 where the direction of 180 is changed. The measurement pipes are separated, but by doing so, the shape of the inlet and outlet of the U-shaped measurement pipe in the forward and reverse directions is the same, so the flow distribution is also equal and accurate. Measurement can be performed. In addition, since the transmission and reception ultrasonic probes are approximately equal in size to the cross-sectional area of the pipeline, the entire radial direction of the pipeline can be scanned, and stable ultrasonic propagation with high reproducibility can be performed. There is an effect that a flow velocity diameter with high accuracy can be actually obtained. In addition, since the shape of the pipe is U-shaped in the measurement portion in this way, an ultrasonic probe approximately equal to the cross-sectional area of the pipe can be attached without blocking the pipe. Furthermore, since the shape of the pipe line of the measurement portion is U-shaped, the reception or transmission ultrasonic probe can be used in both the forward and reverse directions of the flow. For this reason, it is possible to output the same level of output in the direction opposite to the flow direction. In addition, since the same circuit can be used for the receiving circuit, variations in elements, variations in the receiving circuit, and the like can be reduced.
[0046]
  Next, a ninth embodiment of the present invention shown in FIG. 10 will be described. 1 to 9 have the same functions as those of the invention shown in FIG. 1 and will not be described in detail.
[0047]
  A transmission ultrasonic probe 21 approximately equal to the cross-sectional area of the measurement U-shaped conduit 15 installed at the bottom portion of the U-shape of the measurement U-shaped conduit 15, and both the entrance and exit at the top of the measurement U-shaped conduit 15. The reception ultrasonic probe 22 installed in this way, the oscillation circuit 6 that oscillates in response to the oscillation start signal from the calculation unit 7, and outputs to the transmission ultrasonic probe 21, and starts counting by the oscillation start signal from the calculation unit 7. Then, the counter 8 that stops counting by the output of the reception ultrasonic probe 22 and outputs the count information to the calculation unit 7 starts counting by the output of the reception ultrasonic probe 22, and outputs the next reception ultrasonic probe 22. Is provided with a counter 23 for outputting count information to the calculation unit 7 and a pulse width measuring circuit 25 for measuring the output pulse width of the reception ultrasonic probe 22. There.
[0048]
  The signal flow of this configuration will be described with reference to FIG. Since the ultrasonic wave output from the transmission ultrasonic probe 21 passes through two paths in the same direction as the flow and in the opposite direction, it reaches the reception ultrasonic probe 18 with an interval of Δt. If two distant pulses can be identified as shown in FIG. 11A, the flow velocity can be obtained from Δt measured by the counter 19 and t1 measured by the counter 8. However, since the flow velocity is slow as shown in FIG. 11B, Δt cannot be measured when two pulses are observed overlapping each other. Therefore, when the pulse width is equal to or greater than tw as shown in FIG. 11B, the pulse width measurement circuit 25 determines this. In this case, a count stop command is issued at the falling edge of the received pulse by the output of the pulse width measurement circuit 25 so that tr2 is measured by the counter 23. From the pulse width tw2 obtained in this way, Δt is obtained by subtracting the pulse width [tw in FIG. 11 (c)] when a preset flow and forward or reverse ultrasonic waves are received by the calculation unit 7. .
[0049]
  With this configuration, it is possible to measure the ultrasonic propagation time in the same direction as the flow and in the opposite direction at the same time, even when the flow rate is slow, even though it is a simple configuration, instantly stable with low power consumption. This has the effect of realizing a current meter that obtains the measured flow velocity.
[0050]
  Next, another embodiment of the present invention shown in FIG. 10 will be described. 1 to 9 have the same functions as those of the invention shown in FIG. 1 and will not be described in detail.
[0051]
  A transmission ultrasonic probe 21 approximately equal to the cross-sectional area of the measurement U-shaped conduit 15 installed at the bottom portion of the U-shape of the measurement U-shaped conduit 15, and both the entrance and exit at the top of the measurement U-shaped conduit 15. The reception ultrasonic probe 22 installed in this way, the oscillation circuit 6 that oscillates in response to the oscillation start signal from the calculation unit 7, and outputs to the transmission ultrasonic probe 21, and starts counting by the oscillation start signal from the calculation unit 7. Then, the counter 8 that stops counting by the output of the reception ultrasonic probe 22 and outputs the count information to the calculation unit 7 starts counting by the output of the reception ultrasonic probe 22, and outputs the next reception ultrasonic probe 22. Is provided with a counter 23 for outputting count information to the calculation unit 7 and a pulse width measuring circuit 25 for measuring the output pulse width of the reception ultrasonic probe 22. There.
[0052]
  The signal flow of this configuration will be described with reference to FIG. Since the ultrasonic wave output from the transmission ultrasonic probe 21 passes through two paths in the same direction as the flow and in the opposite direction, it reaches the reception ultrasonic probe 18 with an interval of Δt. If two distant pulses can be identified as shown in FIG. 11A, the flow velocity can be obtained from Δt measured by the counter 19 and t1 measured by the counter 8. However, since the flow velocity is slow as shown in FIG. 11B, Δt cannot be measured when two pulses are observed overlapping each other. Therefore, when the pulse width is equal to or greater than tw as shown in FIG. 11B, the pulse width measurement circuit 25 determines this. In this case, a count stop command is issued at the falling edge of the received pulse by the output of the pulse width measuring circuit 25 so that the counter 23 measures tr2. From the pulse width tw2 obtained in this way, Δt is obtained by subtracting the pulse width [tw in FIG. 11 (a)] when a preset flow and forward or reverse ultrasonic waves are received by the calculation unit 7. .
[0053]
  Although tw may be set in advance, since it changes depending on the temperature, the density of the fluid to be measured, etc., it is better to perform correction as needed. Therefore, the pulse width measurement circuit 25 can perform two pulses in one measurement. Is observed, the correction is performed by storing the pulse width at that time in the calculation unit 7 as tw.
[0054]
  With this configuration, it is possible to measure the ultrasonic propagation time in the same direction as the flow and in the opposite direction at the same time, even when the flow rate is slow, even though it is a simple configuration, instantly stable with low power consumption. This has the effect of realizing a current meter that obtains the measured flow velocity.
[0055]
  Next, a tenth embodiment of the present invention shown in FIG. 12 will be described. 1 to 11 function in the same manner as the invention shown in FIG. 1 and will not be described in detail.
[0056]
  The ultrasonic wave output from the transmission ultrasonic probe 21 is shifted by Δt and reaches the reception ultrasonic probe 18. When the received ultrasonic waves are overlapped, if the phases are opposite, the overlapping portions cancel each other, and two short pulses are generated as shown in FIG. 11C. In this case, the pulse width measurement circuit 25 is short. When the pulse is detected, the counter 23 is stopped at the falling edge, and the value is set to Δt to obtain the flow velocity.
[0057]
  With this configuration, it is possible to measure the ultrasonic propagation time in the same direction as the flow and in the opposite direction at the same time, even when the flow rate is slow, even though it is a simple configuration, instantly stable with low power consumption. This has the effect of realizing a current meter that obtains the measured flow velocity. By adopting this configuration, it is possible to simultaneously measure the ultrasonic propagation time in the same direction as the flow and in the opposite direction with a simple configuration, and to realize a velocity meter that instantaneously obtains a stable flow rate with low power consumption. effective.
[0058]
Less thanAs apparent from the above description, the present inventionIn the examplesAccording to the anemometer, the following effects can be obtained.
[0059]
  Since the shield plate that partitions the two pairs of transmitting and receiving ultrasonic probes into one pair is provided, even if the same direction as the flow and the opposite direction are measured at the same time, there is no interference and the flow rate can be reduced in a short operation time. It can measure and provide a low power consumption current meter.
[0060]
  In addition, a shield plate is provided for partitioning the two pairs of transmission / reception ultrasonic probes into one pair, and each of the supersonic waves is separated from the shield plate on the shortest distance from the reception ultrasonic probe of the pair to the other pair of ultrasonic probes. The distance l to the acoustic probe is
          S <L (L: Distance between the same pair of ultrasonic probes)
Since the shielding plate satisfying the above condition is provided, even if an ultrasonic wave output from another pair of transmission ultrasonic probes spills around the reception ultrasonic probe, the output from the same pair of transmission ultrasonic probes is first transmitted. Therefore, even if the same direction as the flow and the opposite direction are measured at the same time, the flow velocity can be measured in a short operation time without interference, and a low power consumption velocity meter can be provided. .
[0061]
  In addition, since the ultrasonic probe is installed in the order of reception, transmission, and reception from the fluid flow direction, one transmission ultrasonic probe can simultaneously output in the forward and reverse directions of the flow, and transmit ultrasonic waves. Since only one probe is required and simultaneous measurement is possible, it is possible to perform measurement quickly and realize an anemometer with reduced power consumption.
[0062]
  Also, ultrasonic probes are installed at equal intervals in the order of reception, transmission, and reception, measurement is started by an oscillation start signal from the calculation unit, and the received ultrasonic probe output is installed upstream or downstream of the fluid flow. The measurement unit 1 that ends the measurement and the measurement unit 2 that starts the measurement by the reception ultrasonic probe installed on the downstream side of the flow and ends the measurement by the reception ultrasonic probe installed on the upstream side of the flow are provided. Therefore, since the measurement of t1 or t2 is separated from the measurement unit 1 and the measurement of Δt is separated from the measurement unit 2, the clock for the measurement unit that measures high-speed Δt does not always have to be operated, and the power consumption is long and low. At the same time, the use of high-speed parts can be limited to one part, so that an inexpensive anemometer can be provided.
[0063]
  In addition, the ultrasonic probe is installed in the direction of fluid flow in the order of reception, transmission, and reception, and the phase inversion circuit is provided on the output on one side of the two reception ultrasonic probes. Since the downstream measurement unit input initial phase is aligned, it is not necessary to output ultrasonic waves of the same phase by using reflection on the transmission side, using both sides of the vibration surface of the ultrasonic element, Since ultrasonic waves can be output efficiently in the same direction as the flow and in the opposite direction, a simple, fair and accurate anemometer can be provided.
[0064]
  A U-shaped measuring pipe having a U-shaped shape in which the fluid flows and having an inlet in the U-shaped end lateral direction and an outlet in the U-shaped upper position at the other end; A transmitting ultrasonic probe 1 that emits ultrasonic waves from a U-shaped bottom position having an outer shape equivalent to the inner diameter of the U-shaped measuring pipe to the entrance of the U-shaped measuring pipe, and an inner diameter of the U-shaped measuring pipe Transmitting ultrasonic probe 2 that emits ultrasonic waves from the U-shaped bottom position having the same outer shape toward the outlet of the U-shaped measurement pipeline, and the U-shape having the same outer shape as the inner diameter of the U-shaped measurement pipeline Receiving ultrasonic probe 1, receiving ultrasonic probe 2, an oscillating circuit for outputting an oscillating signal simultaneously to the transmitting ultrasonic probes 1 and 2, and receiving ultrasonic probe 1 Comprising a measuring unit for measuring a difference in detection time of ultrasonic waves detected by the ultrasonic probe 2 and the reception ultrasonic probe Since then are, it is possible to simultaneously perform ultrasound scans across the cross-section the entire region of the probe between the flow path in the direction and flow and reverse flow, it is possible to obtain a highly reproducible flow rate.
[0065]
  A U-shaped measuring line having a U-shaped shape through which a fluid flows, and having an inlet in a lateral direction of the U-shaped end portion and an outlet in a lateral direction of the U-shaped upper portion at the other end; A transmission ultrasonic probe that emits ultrasonic waves from the U-shaped bottom position toward the inlet and outlet of the U-shaped measurement pipe, and a reception ultrasonic probe 1 provided at each of the inlet and outlet of the U-shaped measurement pipe Since the receiving ultrasonic probe 2 is provided, an ultrasonic output can be output simultaneously in the direction opposite to the same direction as the flow with one transmission ultrasonic probe. Since the direction can be measured, the measurement time can be shortened and a low power consumption current meter can be provided.
[0066]
  A U-shaped measuring line having a U-shaped shape through which a fluid flows, and having an inlet in a lateral direction of the U-shaped end portion and an outlet in a lateral direction of the U-shaped upper portion at the other end; A transmitter ultrasonic probe that emits ultrasonic waves from the U-shaped bottom position toward the inlet and outlet of the U-shaped measurement pipeline, and installed across both the inlet and outlet pipelines of the U-shaped measurement pipeline Since the reception ultrasonic probe is provided, the ultrasonic reception signals in the same direction as the flow and in the opposite direction are handled by one reception path. Since only one reception ultrasonic probe is required, the flowmeter can be realized with high accuracy and low cost.
[0067]
  A U-shaped measuring pipe having a U-shape in the shape of a pipe through which the fluid flows, having an inlet in the lateral direction of the U-shaped end and an outlet in the lateral direction of the U-shaped upper position at the other end; A transmission ultrasonic probe that emits ultrasonic waves from the U-shaped bottom position toward the inlet and outlet of the U-shaped measurement pipe, and a reception ultrasonic probe provided at the inlet and outlet of the U-shaped measurement pipe, Since the U-shaped pipe has a configuration in which the direction of the pipe is further changed to the inlet side and the outlet side of the U-shaped pipe, and is configured as an M-shaped U-shaped measuring pipe. Since the flow path conditions are matched, the flow of fluid is equivalent in the measurement path in the same direction as the flow and in the opposite direction, so that an accurate flow velocity can be measured.
[0068]
  In addition, the flow path of the fluid, the transmission ultrasonic probe that simultaneously emits ultrasonic waves in the direction of fluid flow and in the opposite direction, the reception ultrasonic probe that receives the ultrasonic waves, and the output time width of the reception probe When the pulse width measuring device to be measured and the output of the pulse width measuring device exceed a certain value, the flow rate is obtained by using the difference between the ultrasonic detection time as a value obtained by subtracting the value preset in the calculation unit from the pulse width. Since the configuration is such that the flow of the fluid and the timing of receiving ultrasonic waves with the reception ultrasonic probe in the forward direction and the reverse direction are substantially the same, and the received signals overlap and the pulse width becomes wide, the one direction set in the calculation unit Since the accurate ultrasonic detection time difference is obtained by using the value obtained by subtracting the received pulse width data when receiving only ultrasonic waves as the ultrasonic detection time difference, the flow rate measurement by simultaneous transmission Will be able to be at a low flow rate, it can provide a flow rate meter with low power consumption.
[0069]
  Also, a fluid flow conduit, a transmission ultrasonic probe that simultaneously emits ultrasonic waves in the direction of fluid flow and in the opposite direction, an oscillation circuit that outputs oscillation output to the ultrasonic probe, and reception that receives ultrasonic waves An ultrasonic probe, a measurement unit that operates according to an output of the reception ultrasonic probe and an output of the calculation unit, a pulse width measuring device that measures an output time width of the reception probe, information obtained from the measurement unit, and the pulse width It consists of a calculation unit that obtains the flow velocity according to the output of the measuring device. When the output of the pulse width measuring device exceeds a certain value, the measurement is performed by stopping the oscillation of the ultrasonic wave in the direction of fluid flow, and the pulse obtained at that time. Since the flow velocity is calculated using the difference between the width and the output of the pulse width measuring device as the ultrasonic detection time difference, the ultrasonic wave is received by the receiving ultrasonic probe in the forward and reverse directions of the fluid flow. When the imming is almost the same and the received signals overlap and the pulse width becomes wide, the pulse width is calculated by measuring the pulse width corresponding to the ultrasonic reception time on one side. An accurate ultrasonic wave detection time difference can be obtained even when there is a fluctuation, so that a highly accurate current meter can be realized by the simultaneous ultrasonic transmission method.
[0070]
  Also, a conduit through which the fluid flows, a transmission ultrasonic probe that simultaneously emits ultrasonic waves in the direction of fluid flow and in the opposite direction, an oscillation circuit that outputs an oscillation output to the ultrasonic probe, an upstream direction and a downstream direction of the flow A receiving ultrasonic probe that receives ultrasonic waves from a direction, a measuring unit that operates according to an output of a calculation unit and an output of the receiving ultrasonic probe, and a pulse width measurement that measures an output time width of the receiving probe And when the output of the pulse width measuring device is less than one constant value, the output of the pulse width measuring device. Since the flow velocity of the fluid is measured using the difference in ultrasonic detection time, the timing of receiving ultrasonic waves with the receiving ultrasonic probe in the forward and reverse directions is almost the same as the flow of the fluid. Even when signals are overlapped and received at a timing that cancels out the overlapping parts of the overlapping phases, the accurate ultrasonic detection time difference can be obtained by using pulse width data as the ultrasonic detection time difference. Therefore, it is possible to realize an accurate and low power consumption flowmeter even at a low flow rate.
[0071]
【The invention's effect】
  As described above, according to the present invention, it is possible to perform simultaneous output in the forward and reverse directions of the flow with one transmission ultrasonic probe, and only one transmission ultrasonic probe is required, and simultaneous measurement can be performed. Measurements can be performed quickly, and a current meter with reduced power consumption can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram of an anemometer according to a first embodiment of the present invention.
FIG. 2 is a block diagram of the anemometer in the second embodiment of the present invention.
FIG. 3 is a block diagram of the anemometer in the third embodiment of the present invention.
FIG. 4 is a diagram for explaining the relationship between two counters in the velocimeter
FIG. 5 is a block diagram of an anemometer in the fourth embodiment of the present invention.
FIG. 6 is a block diagram of the anemometer in the fifth embodiment of the present invention.
FIG. 7 is a block diagram of an anemometer in the sixth embodiment of the present invention.
FIG. 8 is a block diagram of the anemometer in the seventh embodiment of the present invention.
FIG. 9 is a block diagram of the anemometer in the eighth embodiment of the present invention.
FIG. 10 is a block diagram of an anemometer in the ninth embodiment of the present invention.
FIG. 11 is a diagram showing the relationship between received pulses in the anemometer
FIG. 12 is a block diagram of an anemometer in the tenth embodiment of the present invention.
FIG. 13 is a block diagram of a conventional anemometer.
[Explanation of symbols]
  1 pipeline
  2, 3 Transmitting ultrasonic probe
  4, 5 Receiving ultrasonic probe
  6 Oscillator circuit
  7 Calculation unit
  8 First measurement unit
  9 Second measurement unit
  10 Shield plate
  12 Phase inversion circuit
  13 Second measurement unit
  15 U-shaped measurement pipeline
  17 First transmission ultrasonic probe
  18 Second transmission ultrasonic probe
  19 First reception ultrasonic probe
  20 Second reception ultrasonic probe
  21 Transmitting ultrasonic probe
  22 receiving ultrasonic probe
  24 Pipelines that change direction
  25 Pulse width measurement circuit

Claims (8)

A first reception ultrasonic probe, a transmission ultrasonic probe, and a second reception ultrasonic probe that are sequentially provided in the pipeline through which the fluid flows, and an oscillation circuit that outputs an oscillation signal to the transmission ultrasonic probe by an oscillation start signal Measurement is started by an oscillation start signal of the oscillation circuit, the measurement is started by the first measurement unit that ends measurement by the output of the second reception ultrasonic probe, and the second reception ultrasonic probe, A flowmeter that includes a second measurement unit that terminates measurement by the first reception ultrasonic probe, and obtains a flow velocity based on outputs of the first measurement unit and the second measurement unit. A first reception ultrasonic probe, a transmission ultrasonic probe, a second reception ultrasonic probe, and a first reception ultrasonic probe connected to each of the first and second reception ultrasonic probes, which are sequentially provided in a conduit through which a fluid flows. The measurement unit and the second measurement unit, a calculation unit that receives time information from the first measurement unit and the second measurement unit, obtains a flow velocity, and receives a signal from the calculation unit and oscillates in the transmission ultrasonic probe and a oscillation circuit for outputting a signal, the flow rate meter provided with a phase inverting circuit either in one of the outputs of the first and second receiving ultrasonic probe.   The shape of the pipe through which the fluid flows is formed in a U-shape, a U-shaped measurement pipe having an inlet and an outlet at each of the U-shaped ends, and a U-shaped measurement pipe from the U-shaped bottom position. A transmission ultrasonic probe that emits ultrasonic waves toward the entrance and the exit of the U-shaped measurement pipe, a first reception ultrasonic probe, and a second reception ultrasonic probe that are respectively provided at the entrance and the exit of the U-shaped measurement conduit; An oscillation circuit for outputting an oscillation signal to the transmission ultrasonic probe, and a measurement for measuring a detection time difference from detection times of the respective ultrasonic waves detected by the first reception ultrasonic probe and the second reception ultrasonic probe And a calculation unit that calculates the flow velocity of the fluid based on the detection time difference.   The shape of the pipe through which the fluid flows is formed in a U-shape, a U-shaped measuring pipe having an inlet and an outlet at each of both ends of the U-shaped, and the U-shaped measuring pipe from the U-shaped bottom position. A transmission ultrasonic probe that emits ultrasonic waves toward the entrance and exit of the road, a reception ultrasonic probe that is installed across both the inlet and the outlet of the U-shaped measurement pipe, and the transmission ultrasonic probe. An oscillation circuit that outputs an oscillation signal to the sonic probe, a measurement unit that measures a detection time difference from the detection time of each ultrasonic wave detected by the reception ultrasonic probe, and a calculation unit that calculates a fluid flow velocity based on the detection time difference An anemometer equipped with.   The shape of the pipe through which the fluid flows is formed in a U-shape, a U-shaped measuring pipe having an inlet and an outlet at each of both ends of the U-shaped, and the U-shaped measuring pipe from the U-shaped bottom position. A transmission ultrasonic probe that emits ultrasonic waves toward the entrance and exit of the road, a reception ultrasonic probe provided at the entrance and exit of the U-shaped measurement pipe, and an oscillation signal output to the transmission ultrasonic probe An oscillation circuit that performs measurement, a measurement unit that measures a detection time difference from a detection time of each ultrasonic wave detected by the reception ultrasonic probe, and a calculation unit that obtains the flow velocity of the fluid based on the detection time difference, the U-shaped An anemometer in which an M-shaped U-shaped measuring line is provided by further providing a line for changing the direction at the same angle as the U-shaped line on the inlet side and the outlet side of the pipe.   A conduit through which a fluid flows, a transmission ultrasonic probe that simultaneously emits ultrasonic waves in a direction opposite to the direction of fluid flow, an oscillation circuit that outputs an oscillation output to the ultrasonic probe, and reception that receives the ultrasonic waves An ultrasonic probe, a measurement unit that operates according to the output of the reception ultrasonic probe, a pulse width measurement device that measures an output time width of the reception probe, information obtained from the measurement unit, and an output of the pulse width measurement device When the output of the pulse width measuring device exceeds a certain value, a value obtained by subtracting a value preset in the calculation unit from the pulse width is used as an ultrasonic detection time difference. An anemometer that determines the flow velocity.   A pipeline through which a fluid flows, a transmission ultrasonic probe that simultaneously emits ultrasonic waves in the direction of fluid flow and in the opposite direction, an oscillation circuit that outputs an oscillation output to the ultrasonic probe, and a reception ultrasonic wave that receives ultrasonic waves An acoustic probe, a measurement unit that operates according to an output of the reception ultrasonic probe and an output of the calculation unit, a pulse width measurement device that measures an output time width of the reception probe, information obtained from the measurement unit, and the pulse width measurement A calculation unit that obtains the flow velocity according to the output of the vessel, and when the output of the pulse width measuring device exceeds a certain value, the oscillation of ultrasonic waves in the direction of fluid flow is stopped, and the measured pulse width is An anemometer that obtains the flow velocity using the difference in ultrasonic detection time as the value subtracted from the output of the pulse width measuring instrument.   A conduit through which fluid flows, a transmission ultrasonic probe that simultaneously emits ultrasonic waves in the direction of fluid flow and in the opposite direction, an oscillation circuit that outputs an oscillation output to the ultrasonic probe, and upstream and downstream directions of the flow A reception ultrasonic probe for receiving the ultrasonic wave coming from, a measurement unit that operates according to an output of the calculation unit output and the reception ultrasonic probe, a pulse width measurement device that measures an output time width of the reception probe, and The information obtained from the measurement unit and the calculation unit for obtaining the flow velocity by the output of the pulse width measuring device, and when the output of the pulse width measuring device is below a certain value, the output of the pulse width measuring device is used. An anemometer that measures the flow rate of fluid.

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