Wind speed sensor, wind speed measurement method, and program

Abstract

To improve accuracy of wind speed measurement.SOLUTION: A wind speed sensor according to the present invention includes a flow path, a first transceiver that transmits a first ultrasonic wave to the flow path, a second transceiver that transmits a second ultrasonic wave to the flow path, and a measurement unit. When the first ultrasonic wave received by the second transceiver via the flow path during wind speed measurement is defined as a first observation wave, the second ultrasonic wave received by the first transceiver via the flow path during wind speed measurement is defined as a second observation wave, and at least one of the first ultrasonic wave received by the second transceiver through the flow path under a reference condition and the second ultrasonic wave received by the first transceiver through the flow path under the reference condition is defined as a reference wave, the measurement unit measures the wind speed in the flow path by using a first time difference between the reference wave and the first observation wave and a second time difference between the reference wave and the second observation wave.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wind speed sensor, a wind speed measurement method, and a program. [Background technology]

[0002] BACKGROUND ART Conventionally, there is known a wind speed sensor that includes a pair of ultrasonic transmitters and receivers and measures wind speed based on the phase difference between ultrasonic waves transmitted from the respective ultrasonic transmitters and receivers (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-139865 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the wind speed increases, the phase difference between the ultrasonic waves may exceed the value of one cycle of the ultrasonic waves, which may result in the measured wind speed being different from the actual wind speed.

[0005] An object of the present invention is to provide a wind speed sensor, a wind speed measurement method, and a program that improve the accuracy of wind speed measurement. [Means for solving the problem]

[0006] This wind speed sensor comprises a flow path, a first transceiver that transmits a first ultrasonic wave into the flow path, a second transceiver that transmits a second ultrasonic wave into the flow path, and a measurement unit. When measuring wind speed, the first ultrasonic wave received by the second transceiver through the flow path is taken as a first observation wave, and the second ultrasonic wave received by the first transceiver through the flow path during wind speed measurement is taken as a second observation wave. When at least one of the first ultrasonic wave received by the second transceiver through the flow path under standard conditions and the second ultrasonic wave received by the first transceiver through the flow path under the standard conditions is taken as a reference wave, the measurement unit measures the wind speed in the flow path using a first time difference between the reference wave and the first observation wave and a second time difference between the reference wave and the second observation wave. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a wind speed sensor, a wind speed measurement method, and a program that improve the accuracy of wind speed measurement. [Brief explanation of the drawings]

[0008] [Figure 1] 1(a) is a plan view of the wind speed sensor according to the embodiment, and FIG. 1(b) is a cross-sectional view schematically showing an example of a cross section of the wind speed sensor according to the embodiment taken along line IB-IB shown in FIG. 1(a). [Figure 2] FIG. 2 is a block diagram illustrating an example of the configuration of a measurement unit included in the wind speed sensor according to the embodiment. [Figure 3] 10 is an example of a schematic graph showing waveforms of signals corresponding to a first observation wave and a second observation wave in a comparative example. [Figure 4] 4 is an example of a schematic graph showing waveforms of signals corresponding to a first observation wave, a second observation wave, and a reference wave in an embodiment. [Figure 5] 1 is a flowchart illustrating an example of a wind speed measurement method according to an embodiment. [Figure 6] FIG. 10 is a cross-sectional view schematically showing an example of a cross section of a wind speed sensor according to a modified example taken along an XZ plane. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes the preferred embodiments of the present invention with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals, and redundant explanations will be omitted where appropriate.

[0010] In the drawings, directions are expressed using a Cartesian coordinate system having an X-axis, a Y-axis, and a Z-axis. The X-axis, the Y-axis, and the Z-axis are perpendicular to one another. The direction along the X-axis is referred to as the X-axis direction. The direction along the Y-axis is referred to as the Y-axis direction. The direction along the Z-axis is referred to as the Z-axis direction. In addition, in the X-axis direction, the direction in which the arrow points is referred to as the +X direction or +X side, and the direction opposite to the +X direction is referred to as the -X direction or -X side. In the Y-axis direction, the direction in which the arrow points is referred to as the +Y direction or +Y side, and the direction opposite to the +Y direction is referred to as the -Y direction or -Y side. In the Z-axis direction, the direction in which the arrow points is referred to as the +Z direction or +Z side, and the direction opposite to the +Z direction is referred to as the -Z direction or -Z side. In this specification, the +Z direction or +Z side may be referred to as "up." In addition, the -Z direction or -Z side may be referred to as "down."

[0011] In this specification and claims, "along a direction" means that two axes or directions are parallel with a difference of ±5 degrees or less. Also, "orthogonal" includes angles in the range of 90 degrees ±5 degrees relative to any direction. However, these directional expressions do not limit the directions of the embodiments. The wind speed sensor can be oriented in any direction when in use.

[0012] [Embodiment] <Configuration example> An example of the configuration of a wind speed sensor 1 according to an embodiment will be described with reference to FIGS. 1 to 4. FIG. 1(a) is a plan view of the wind speed sensor according to the embodiment. FIG. 1(b) is a cross-sectional view schematically showing an example of a cross section of the wind speed sensor 1 according to the embodiment taken along line IB-IB shown in FIG. 1(a). FIG. 2 is a block diagram schematically showing an example of the configuration of a measurement unit 40 included in the wind speed sensor 1 according to the embodiment. FIG. 3 is an example of a schematic graph showing waveforms of signals corresponding to the first observation wave and the second observation wave in a comparative example. FIG. 4 is an example of a schematic graph showing waveforms of signals corresponding to the first observation wave, the second observation wave, and the reference wave in the embodiment.

[0013] 1(a) and 1(b), the wind speed sensor 1 includes a flow path 10, a first transceiver 20, a second transceiver 30, a third transceiver 21, a fourth transceiver 31, and a measurement unit 40. The wind speed sensor 1 may further include a housing 50 that houses the first transceiver 20, the second transceiver 30, the third transceiver 21, the fourth transceiver 31, and the measurement unit 40. The housing 50 includes, for example, a top plate 51, a bottom plate 52, and a plurality of support columns 53. In the embodiment, the bottom plate 52 functions as a reflector that reflects ultrasonic waves transmitted from the first transceiver 20, the second transceiver 30, the third transceiver 21, and the fourth transceiver 31 toward the top plate 51.

[0014] 1(b), the top plate 51 and the bottom plate 52 face each other with the flow path 10 in between. The top plate 51 is disposed above the flow path 10. The bottom plate 52 is disposed below the flow path 10. In other words, the space provided between the top plate 51 and the bottom plate 52 corresponds to the flow path 10.

[0015] Each of the plurality of support columns 53 is disposed between the top plate 51 and the bottom plate 52. Each of the plurality of support columns 53 is disposed on the bottom plate 52 and supports the top plate 51. In the example shown in Fig. 1, two support columns 53 are shown, but the number of support columns 53 may be three or more.

[0016] (First transceiver 20 and second transceiver 30) An example configuration of the first transceiver 20 and the second transceiver 30 will be described. As shown in FIG. 1(b), the first transceiver 20 and the second transceiver 30 are fixed to the surface of the top plate 51 facing the flow path 10. Each of the first transceiver 20 and the second transceiver 30 includes a transmitter that transmits ultrasonic waves to the flow path 10 and a receiver that receives ultrasonic waves. The transmitter and receiver in each of the first transceiver 20 and the second transceiver 30 may be composed of a piezoelectric element including a piezoelectric ceramic and an electrode. The transmitter and receiver may be structurally integrated or structurally separate. Note that the third transceiver 21 and the first transceiver 20 have the same function, so the first transceiver 20 will be used as an example for the description. The fourth transceiver 31 and the second transceiver 30 have the same function, so the second transceiver 30 will be used as an example for the description.

[0017] In the example shown in FIG. 1 , the transmitting and receiving surfaces included in the transmitting unit and receiving unit of the first transceiver 20 face the flow path 10. Furthermore, the transmitting and receiving surfaces included in the transmitting unit and receiving unit of the first transceiver 20 may be inclined at a predetermined angle with respect to the XY plane. In the first transceiver 20, the angle of the transmitting and receiving surfaces with respect to the XY plane may be referred to as the "orientation of the first transceiver 20." The transmitting and receiving surfaces included in the transmitting unit and receiving unit of the second transceiver 30 face the flow path 10. Furthermore, the transmitting and receiving surfaces included in the transmitting unit and receiving unit of the second transceiver 30 may be inclined at a predetermined angle with respect to the XY plane. In the second transceiver 30, the angle of the transmitting and receiving surfaces with respect to the XY plane may be referred to as the "orientation of the second transceiver 30."

[0018] The ultrasonic wave transmitted from the first transceiver 20 is referred to as the "first ultrasonic wave 20u." As shown in FIG. 1(b), the first ultrasonic wave 20u transmitted from the first transceiver 20 toward the flow path 10 is reflected by the bottom plate 52 and received by the second transceiver 30. During wind speed measurement, the first ultrasonic wave 20u received by the second transceiver 30 via the flow path 10 is referred to as the "first observation wave 20u1."

[0019] The ultrasonic wave transmitted from the second transceiver 30 is referred to as the "second ultrasonic wave 30u." As shown in FIG. 1(b), the second ultrasonic wave 30u transmitted from the second transceiver 30 toward the flow path 10 is reflected by the bottom plate 52 and received by the first transceiver 20. During wind speed measurement, the second ultrasonic wave 30u received by the first transceiver 20 via the flow path 10 is referred to as the "second observation wave 30u1."

[0020] In the example shown in FIGS. 1(a) and 1(b), the first transceiver 20 and the second transceiver 30 are disposed at positions spaced apart from each other along the X-axis direction. For example, the first transceiver 20 is disposed on the -X side, and the second transceiver 30 is disposed on the +X side. However, the positions of the first transceiver 20 and the second transceiver 30 are not limited to this. For example, the first transceiver 20 and the second transceiver 30 may be disposed at positions spaced apart from each other along the Y-axis direction. Alternatively, the first transceiver 20 may be disposed on the top panel 51 side, and the second transceiver 30 may be disposed on the bottom panel 52 side so as to face the first transceiver 20. Conversely, the first transceiver 20 may be disposed on the bottom panel 52 side, and the second transceiver 30 may be disposed on the top panel 51 side so as to face the first transceiver 20.

[0021] The number of transceivers included in the wind sensor 1 is not limited to two, the first transceiver 20 and the second transceiver 30. That is, the wind sensor 1 may further include one or more other transceivers that transmit and receive ultrasonic waves in addition to the first transceiver 20 and the second transceiver 30. The other transceivers may receive ultrasonic waves transmitted from another transceiver via the flow path 10, similar to the first transceiver 20 and the second transceiver 30. For example, if the first transceiver 20 and the second transceiver 30 are arranged along the X-axis direction, two other transceivers may be provided that are arranged along the Y-axis direction. By including a transceiver arranged along the X-axis direction (e.g., the first transceiver 20 and the second transceiver 30) and a transceiver arranged along the Y-axis direction, the wind sensor 1 can measure the X-axis component Vx and the Y-axis component Vy of the wind speed V, respectively. Furthermore, the wind sensor 1 can measure the wind direction based on the X-axis component Vx and the Y-axis component Vy of the wind speed V. However, the positions and number of the transceivers are not limited.

[0022] The first ultrasonic wave 20u received by the second transceiver 30 through the flow path 10 under the reference condition BC is referred to as the "first reference wave 20b." Also, the second ultrasonic wave 30u received by the first transceiver 20 through the flow path 10 under the reference condition BC is referred to as the "second reference wave 30b." The first reference wave 20b and the second reference wave 30b are collectively referred to as the "reference wave BW." In other words, the "reference wave BW" corresponds to at least one of the first reference wave 20b and the second reference wave 30b.

[0023] An example of the reference condition BC is when the wind speed V in the flow path 10 is zero. In this case, the first reference wave 20b corresponds to the first ultrasonic wave 20u measured when the wind speed V in the flow path 10 is zero. The second reference wave 30b corresponds to the second ultrasonic wave 30u measured when the wind speed V in the flow path 10 is zero. The timing at which the first reference wave 20b and the second reference wave 30b are measured may be, for example, a timing different from the timing at which the wind speed is measured. Note that in the following description, the reference condition BC is defined as when the wind speed V in the flow path 10 is zero, but the reference condition BC is not limited to when the wind speed V is zero.

[0024] (Measurement unit 40) Next, an example configuration of the measurement unit 40 will be described. The measurement unit 40 calculates the wind speed V in the flow path 10 based on data from the first transceiver 20 and the second transceiver 30. The measurement unit 40 may also calculate the wind direction. The measurement unit 40 may further have a function of displaying the calculation results of the wind speed V, etc. The measurement unit 40 may also output the calculation results of the wind speed V, etc. to an external information processing device. As shown in FIG. 2, the measurement unit 40 includes a signal generation circuit 410, a detection circuit 420, a temperature sensor 430, and a control circuit 440. The measurement unit 40 may be a computer including these circuits. The measurement unit 40 calculates the X-axis component Vx of the wind speed V using the data from the first transceiver 20 and the second transceiver 30, and the Y-axis component Vy of the wind speed V using the data from the third transceiver 21 and the fourth transceiver 31.

[0025] The signal generation circuit 410 generates an AC signal that is the source of the first observation wave 20u1 and outputs the generated AC signal to the first transceiver 20. The signal generation circuit 410 also generates an AC signal that is the source of the second observation wave 30u1 and outputs the generated AC signal to the second transceiver 30. An example of the AC signal generated by the signal generation circuit 410 is an analog electrical signal that corresponds to a sine wave having a predetermined period and amplitude. It is preferable that the sine wave corresponding to the AC signal to the first transceiver 20 and the sine wave corresponding to the AC signal to the second transceiver 30 have approximately the same period (frequency).

[0026] An example of the signal generating circuit 410 is a circuit including an oscillator circuit including a quartz crystal oscillator, a digital-to-analog converter that converts a digital signal such as a pulse signal oscillated from the oscillator circuit into an analog AC signal, and a switching circuit that switches a transceiver to which the AC signal is output in accordance with a selection signal input from a control circuit 440, which will be described separately. However, the configuration of the signal generating circuit 410 is not limited to this.

[0027] The detection circuit 420 detects a signal related to the second observation wave 30u1 received by the first transceiver 20. The signal related to the second observation wave 30u1 will be referred to below as the "second signal 30S." The detection circuit 420 also detects a signal related to the first observation wave 20u1 received by the second transceiver 30. The signal related to the first observation wave 20u1 will be referred to below as the "first signal 20S." The detection circuit 420 outputs each of the detected first signal 20S and second signal 30S to the control circuit 440. The detection circuit 420 also detects a signal related to the reference wave BW when measuring the reference wave BW. The signal related to the reference wave BW will be referred to below as the "reference signal BWS." The signal related to the first reference wave 20b of the reference wave BW will be referred to below as the "first reference signal." The signal related to the second reference wave 30b of the reference wave BW will be referred to as the "second reference signal."

[0028] An example of the detection circuit 420 is a circuit including a switching circuit that switches the output signal to the control circuit 440 between the first signal 20S and the second signal 30S, an amplifier circuit that amplifies the first signal 20S or the second signal 30S output through the switching circuit, and an analog-to-digital converter that converts an analog AC signal related to the amplified first signal 20S or the second signal 30S into a digital signal. However, the configuration of the detection circuit 420 is not limited to this.

[0029] The temperature sensor 430 detects, for example, the temperature inside the flow path 10 when the reference wave BW is measured. The temperature sensor 430 may also detect the temperature inside the flow path 10 when wind speed is measured. The temperature sensor 430 outputs information related to the detected temperature to the control circuit 440. The information related to the temperature detected by the temperature sensor 430 may be stored in the memory 442 of the control circuit 440. The information related to the temperature detected by the temperature sensor 430 is used, for example, when calculating the sound speed C0 of the reference wave BW.

[0030] The type of temperature sensor 430 is not limited as long as it can detect the temperature inside the flow path 10. Examples of the temperature sensor 430 include a thermistor, a linear resistor, a platinum resistance thermometer, a thermocouple, and a thermopile.

[0031] The control circuit 440 includes, for example, a processor 441 such as a CPU (Central Processing Unit), a memory 442 such as a ROM (Read Only Memory), and a bus 448 that electrically connects the processor 441 and the memory 442 to each other. The memory 442 is an example of a "storage medium." The processor 441 executes various processes, which will be described later, in accordance with, for example, a program stored in the memory 442. The program, when executed by the processor 441, causes the measurement unit 40 to function as a means for measuring the wind speed V, for example. The program may be stored in an external storage medium such as a hard disk or a flash memory. The program may also be transmitted to the control circuit 440 via a communication line. The transmitted program is installed in the memory 442 of the control circuit 440.

[0032] Examples of information stored in the memory 442 include waveform information of the reference signal BWS including the first reference signal and the second reference signal, and the propagation time T0 and propagation distance L0 of the reference wave BW. The propagation time T0 and propagation distance L0 of the reference wave BW may be calculated based on information about the time point at which the peak value of the reference signal BWS reaches a predetermined value (e.g., the time point at which the peak value of the reference signal BWS reaches zero). Examples of the propagation time T0 of the reference wave BW include at least one of the time from when the first reference wave 20b transmitted from the first transceiver 20 is reflected by the bottom plate 52 and received by the second transceiver 30 under reference conditions BC at a reference temperature TE0 to when the second reference wave 30b transmitted from the second transceiver 30 is reflected by the bottom plate 52 and received by the first transceiver 20 under reference conditions BC. For example, the reference temperature TE0 can be room temperature or a temperature close to room temperature (approximately 15°C). That is, an example of the propagation time T0 of the reference wave BW is the propagation time between the first transceiver 20 and the second transceiver 30 via the flow path 10 at the sound speed C0 at the reference temperature TE0. Furthermore, an example of the propagation distance L0 of the reference wave BW is the distance corresponding to the path of the first reference wave 20b transmitted from the first transceiver 20, reflected by the bottom plate 52, and then received by the second transceiver 30, or the distance corresponding to the path of the second reference wave 30b transmitted from the second transceiver 30, reflected by the bottom plate 52, and then received by the first transceiver 20. That is, an example of the propagation distance L0 of the reference wave BW is the propagation distance of the reference wave BW between the first transceiver 20 and the second transceiver 30 via the flow path 10.

[0033] The propagation time T0 may be calculated by the control circuit 440 of the measurement unit 40 or by an external measurement device. The propagation distance L0 may be calculated based on, for example, design values ​​for the position and orientation of the first transceiver 20, the position and orientation of the second transceiver 30, the distance between the first transceiver 20 and the bottom plate 52, and the distance between the second transceiver 30 and the bottom plate 52. The propagation distance L0 may also be calculated based on, for example, the propagation time T0 and the sonic speed C0 of the reference wave BW calculated from the temperature (reference temperature TE0) in the flow path 10 at the time of measuring the reference wave BW. The propagation distance L0 may be calculated by the control circuit 440 of the measurement unit 40 or by an external measurement device. The propagation time T0 and the propagation distance L0 may be obtained by measuring the reference wave BW in advance before measuring the wind speed V. For example, the propagation time T0 and the propagation distance L0 may be obtained by measuring the reference wave BW before the wind speed sensor 1 is shipped.

[0034] The control circuit 440 outputs a selection signal to the signal generation circuit 410 to select a transceiver that will transmit an ultrasonic wave to the flow path 10 from among a plurality of transceivers including the first transceiver 20 and the second transceiver 30. In response to the selection signal, the signal generation circuit 410 outputs an AC signal that is the source of the first observation wave 20u1 to the first transceiver 20, or outputs an AC signal that is the source of the second observation wave 30u1 to the second transceiver 30.

[0035] The control circuit 440 may control the output timing of a first selection signal that selects the first transceiver 20 as the transceiver that transmits ultrasonic waves to the flow channel 10, and the output timing of a second selection signal that selects the second transceiver 30 as the transceiver that transmits ultrasonic waves to the flow channel 10. The control circuit 440 may output each of the first selection signal and the second selection signal at any timing, or may output the first selection signal and the second selection signal with a predetermined time difference. An example of the predetermined time difference is a time equal to or longer than the time from when the first transceiver 20 transmits the first observation wave 20u1 to when the second transceiver 30 receives the first observation wave 20u1.

[0036] The control circuit 440 measures the wind speed V in the flow path based on the first signal 20S and the second signal 30S input from the detection circuit 420 and the reference signal BWS stored in, for example, the memory 442. An example of the calculation principle of the wind speed V will be described. As a premise, an example of calculating the wind speed V will be described.

[0037] For ease of explanation, it is assumed that the air in the flow path 10 flows from the -X side to the +X side. That is, the wind speed V is expressed by a vector pointing from the -X side to the +X side. However, the direction in which the air flows in the flow path 10 (i.e., the wind direction) is not limited to this.

[0038] The first observation wave 20u1, transmitted from the first transceiver 20 located on the -X side and received by the second transceiver 30 located on the +X side, experiences a tailwind. In contrast, the second observation wave 30u1, transmitted from the second transceiver 30 located on the +X side and received by the first transceiver 20 located on the -X side, experiences a headwind. As a result, the propagation time T1 of the first observation wave 20u1 is shorter than the propagation time T2 of the second observation wave 30u1. Note that an example of the propagation time T1 is the time from when the first observation wave 20u1 is transmitted from the first transceiver 20 to when it is reflected by the bottom plate 52 of the housing 50 and received by the second transceiver 30. In other words, an example of the propagation time T1 is the propagation time of the first observation wave 20u1 between the first transceiver 20 and the second transceiver 30 via the flow path 10. An example of the propagation time T2 is the time it takes for the second observation wave 30u1 to be transmitted from the second transceiver 30, reflected by the bottom plate 52 of the housing 50, and then received by the first transceiver 20. That is, an example of the propagation time T2 is the time it takes for the second observation wave 30u1 to propagate between the second transceiver 30 and the first transceiver 20 via the flow path 10.

[0039] The propagation distance of the first observation wave 20u1 from the first transceiver 20 to the second transceiver 30, or the propagation distance of the second observation wave 30u1 from the second transceiver 30 to the first transceiver 20, is assumed to be the same as the propagation distance L0 of the reference wave BW. Furthermore, the sound speed of the first observation wave 20u1 or the second observation wave 30u1 is assumed to be C1. Theoretically, since the sound speed varies depending on temperature, if the measurement environments for the first observation wave 20u1 and the second observation wave 30u1 are substantially the same (i.e., the temperatures are substantially the same), the sound speed of the first observation wave 20u1 and the sound speed of the second observation wave 30u1 can be considered to be the same.

[0040] The propagation time T1 of the first observation wave 20u1 and the propagation time T2 of the second observation wave 30u1 are expressed by the formulas (1) and (2), respectively, using the propagation distance L0, the sound speed C1, and the wind speed V. T1=L0 / (C1+V) (1) T2=L0 / (C1-V) (2)

[0041] Furthermore, equation (3) regarding wind speed V can be obtained from [equation (1)-equation (2)]. V=(L0 / 2)[(1 / T1)-(1 / T2)] ···(3)

[0042] Next, an example of the measurement principle of wind speed V will be described. First, with reference to FIG. 3, an example of the measurement principle of wind speed V for a comparative example will be described. The horizontal axis of FIG. 3 represents the elapsed time from the start of transmission of the first observation wave 20u1 or the second observation wave 30u1. The origin of the horizontal axis of FIG. 3 corresponds to a predetermined time after the start of transmission of the first observation wave 20u1 or the second observation wave 30u1. The vertical axis of FIG. 3 represents the amplitude of the first signal 20S corresponding to the first observation wave 20u1 and the second signal 30S corresponding to the second observation wave 30u1. FIG. 3(a) shows the waveforms of the first signal 20S and the second signal 30S when the wind speed V in the flow path 10 is Va [m / s]. Note that Va is a non-zero value. FIG. 3(b) shows the waveforms of the first signal 20S and the second signal 30S when the wind speed V in the flow path 10 is Vb [m / s], which is greater than Va.

[0043] In the comparative example, for example, a time point at which the peak value of the first signal 20S becomes zero (time point t20a in FIG. 3A) is detected for the propagation time T1, and a time point at which the peak value of the second signal 30S becomes zero (time point t30a in FIG. 3A) is detected for the propagation time T2. Time point t20a is set to be a time point belonging to the n-th period of the first signal 20S. Time point t30a is set to be a time point belonging to the n-th period of the second signal 30S. In other words, time point t20a and time point t30a are time points identified by the same peak value that belong to the same numbered periods of the first signal 20S and the second signal 30S. Note that for the propagation time T1, a time point at which the peak value of the first signal 20S is a value other than zero may be detected. For the propagation time T2, a time point at which the peak value of the second signal 30S is a value other than zero may be detected.

[0044] 3(a), if the difference between the phase corresponding to time t20a of the first signal 20S and the phase corresponding to time t30a of the second signal 30S is equal to or less than the value of one period of the first signal 20S or the second signal 30S (for example, 2π), the points in time at which the first signal 20S and the second signal 30S have the same peak value and belong to the same numbered periods will be close in time series. Therefore, the points in time at which the first signal 20S and the second signal 30S have the same peak value and belong to the same numbered periods will be properly detected.

[0045] On the other hand, as shown in FIG. 3(b), when the wind speed V increases, the difference between the phase corresponding to time t20a of the first signal 20S and the phase corresponding to time t30a of the second signal 30S exceeds the value of one period of the first signal 20S or the second signal 30S. In this case, the points in time at which the first signal 20S and the second signal 30S have the same peak value but belong to the same numbered periods are chronologically distant from each other. Therefore, for example, in the second signal 30S, there is a possibility that point t30b, which belongs to the (n-1)th period and is close to point t20a of the first signal 20S, may be detected. The same applies to the first signal 20S. That is, there is a possibility that points in time at which the first signal 20S and the second signal 30S have the same peak value but belong to different numbered periods may be detected, resulting in an erroneous measurement of the wind speed V.

[0046] Here, if the starting points of the first signal 20S and the second signal 30S are aligned, the nth period can be correctly determined. However, it is assumed that vibrations caused when the first transceiver 20 transmits the first observation wave 20u1 are transmitted to the second transceiver 30 via the top panel 51, making it impossible to determine the start point of the first signal 20S. This phenomenon is called casing propagation. Similarly, it is assumed that the start point of the second signal 30S cannot be determined due to casing propagation. Therefore, the nth period of the first signal 20S is determined to be time t20a, which is a predetermined time after the first transceiver 20 starts transmitting the first observation wave 20u1. Similarly, the nth period of the second signal 30S is determined to be time t30a, which is a predetermined time after the second transceiver 30 starts transmitting the second observation wave 30u1.

[0047] To prevent such erroneous measurement of the wind speed V, in this embodiment, a reference signal BWS is used in addition to the first signal 20S and the second signal 30S. An example of the measurement principle of the wind speed V according to this embodiment will be described with reference to FIG. 4 . The horizontal axis of FIG. 4 represents the elapsed time from the start of transmission of the first observation wave 20u1, the second observation wave 30u1, or the reference wave BW. The origin of the horizontal axis of FIG. 4 corresponds to a predetermined time after the start of transmission of the first observation wave 20u1, the second observation wave 30u1, or the reference wave BW. The vertical axis of FIG. 4 represents the amplitude of each of the first signal 20S, the second signal 30S, and the reference signal BWS. FIG. 4(a) shows the waveforms of the first signal 20S, the second signal 30S, and the reference signal BWS when the wind speed V in the flow path 10 is Va. FIG. 4(b) shows the waveform of the first signal 20S, the waveform of the second signal 30S, and the waveform of the reference signal BWS when the wind speed V in the flow path 10 is Vb.

[0048] In the embodiment, the wind speed V in the flow path 10 is measured using a first time difference Δt1 between the reference wave BW and the first observation wave 20u1 and a second time difference Δt2 between the reference wave BW and the second observation wave 30u1. For example, in the example shown in FIG. 4 , the wind speed V is measured using the first time difference Δt1 between time t20a at which the peak value of the nth period in the first signal 20S becomes zero and time t40a at which the peak value of the nth period in the reference signal BWS becomes zero, and the second time difference Δt2 between time t30a at which the peak value of the nth period in the second signal 30S becomes zero and time t40a at which the peak value of the nth period in the reference signal BWS becomes zero. Note that, similarly to the embodiment, the peak value at which the first signal 20S is detected may be a value other than zero. The detection time of the first signal 20S, including time t20a, is an example of a “first time point.” The peak value at which the second signal 30S is detected may be a value other than zero. The detection time points of the second signal 30S, including time point t30a, are examples of "second time points." The peak value at which the reference signal BWS is detected may be a value other than zero. The detection time points of the reference signal BWS, including time point t40a, are examples of "reference time points."

[0049] Because the reference wave BW is an ultrasonic wave measured under reference conditions BC, such as when the wind speed is zero, the propagation time T0 is longer than the propagation time T1 and shorter than the propagation time T2. That is, in each of the first signal 20S, the second signal 30S, and the reference signal BWS, the points at which the crest value is zero that belong to the n-th period are arranged in chronological order as follows: point t20a for the first signal 20S, point t40a for the reference signal BWS, and point t30a for the second signal 30S.

[0050] As shown in FIG. 4(b), the chronological order of time t20a, time t40a, and time t30a can be established even if the difference between the phase of the first signal 20S corresponding to time t20a and the phase of the second signal 30S corresponding to time t30a exceeds the value of one cycle of the first signal 20S or the second signal 30S. Therefore, if time t20a for the first signal 20S, time t40a for the reference signal BWS, and time t30a for the second signal 30S are not detected in this order, the measurement unit 40 can determine that it has not detected time points that belong to the same numbered cycles of each signal. This prevents the detection of time points that belong to different numbered cycles of the first signal 20S and the second signal 30S, as in the comparative example. As a result, erroneous measurement of the wind speed V can be prevented.

[0051] Furthermore, in consideration of the case where at least one of the position and orientation of the first transceiver 20, the position and orientation of the second transceiver 30, the distance between the first transceiver 20 and the bottom plate 52, and the distance between the second transceiver 30 and the bottom plate 52 deviates from their respective design values, the first time difference Δt1 may be the time difference between the first observation wave 20u1 and the first reference wave 20b, and the second time difference Δt2 may be the time difference between the second observation wave 30u1 and the second reference wave 30b. This can further reduce measurement errors in the wind speed V.

[0052] Based on an example of the measurement principle of wind speed V in this embodiment, the measurement unit 40 executes the following measurement process. Note that, when the propagation time T0 of the reference wave BW is used, the propagation time T1 of the first observation wave 20u1 in equation (1) can be replaced with Δt1 + T0 (where Δt1 is a negative value). Furthermore, the propagation time T2 of the second observation wave 30u1 in equation (2) can be replaced with Δt2 + T0 (where Δt2 is a positive value). Therefore, the wind speed V can be calculated using equation (4). V=(L0 / 2)×[{1 / (Δt1+T0)}-{1 / (Δt2+T0)}] ···(4)

[0053] The measurement unit 40 performs the following process to calculate Δt1. The measurement unit 40 detects a first time point from the first signal 20S. For example, the measurement unit 40 detects time point t20a as the first time point. The measurement unit 40 detects a second time point from the second signal 30S. For example, the measurement unit 40 detects time point t30a as the second time point. The measurement unit 40 detects a reference time point from the reference signal BWS. For example, the measurement unit 40 detects time point t40a as the reference time point. The measurement unit 40 may include a zero-cross circuit for detecting time points t20a, t30a, and t40a. Note that the measurement unit 40 may detect the first time point, the second time point, and the reference time point after a predetermined time has elapsed since the start of measurement. This allows the first time point, the second time point, and the reference time point to be detected when the waveforms of the first signal 20S, the second signal 30S, and the reference signal BWS each approach a periodic shape.

[0054] The measurement unit 40 calculates the first time difference Δt1 based on the time difference between the first time point and the reference time point. For example, the measurement unit 40 calculates the first time difference Δt1 based on the time difference between time point t20a and time point t40a. The measurement unit 40 also calculates the second time difference Δt2 based on the time difference between the second time point and the reference time point. For example, the measurement unit 40 calculates the second time difference Δt2 based on the time difference between time point t30a and time point t40a. The measurement unit 40 also measures the wind speed V by substituting the first time difference Δt1 and the second time difference Δt2 into equation (4).

[0055] The measuring unit 40 may detect m first time points in the first signal 20S at which the peak value of each of the periods from the nth period to the [n+m]th period (where m is a natural number) becomes zero. Note that each of the m first time points may be a time point at which the peak value of each of the periods from the nth period to the [n+m]th period corresponds to a value other than zero. However, it is preferable that the peak values ​​of each of the periods from the nth period to the [n+m]th period (where m is a natural number) are the same.

[0056] The measuring unit 40 may detect m second time points in the second signal 30S at which the peak value of each of the periods from the nth period to the [n+m]th period is zero. Note that each of the m second time points may be a time point at which the peak value of each of the periods from the nth period to the [n+m]th period corresponds to a value other than zero. However, it is preferable that the peak values ​​of each of the periods from the nth period to the [n+m]th period (where m is a natural number) are the same.

[0057] The measuring section 40 may detect m reference time points in the reference signal BWS at which the crest value of each of the nth to [n+m]th periods is zero. Note that each of the m reference time points may be a time point at which the crest value of each of the nth to [n+m]th periods corresponds to a value other than zero. However, it is preferable that the crest values ​​of each of the nth to [n+m]th periods (where m is a natural number) are the same.

[0058] Furthermore, the measurement unit 40 may calculate the time difference between the first time points and the reference time points in the same number of cycles among the m first time points and the m reference time points, and calculate the first time difference Δt1 based on the average value of these time differences. For example, the measurement unit 40 may calculate the time difference between the first time points and the reference time points in the nth cycle, the time difference between the first time points and the reference time points in the [n+1]th cycle, the time difference between the first time points and the reference time points in the [n+2]th cycle, and the time difference between the first time points and the reference time points in the [n+m]th cycle, and calculate the first time difference Δt1 from the average value of these time differences.

[0059] The measurement unit 40 may calculate the time difference between the second time points and the reference time points in the same number of cycles among the m second time points and the m reference time points, and may calculate the second time difference based on the average value of the time differences. For example, the measurement unit 40 may calculate the time difference between the second time points and the reference time points in the nth cycle, the time difference between the second time points and the reference time points in the [n+1]th cycle, the time difference between the second time points and the reference time points in the [n+2]th cycle, and the time difference between the second time points and the reference time points in the [n+m]th cycle, and calculate the second time difference Δt2 from the average value of these time differences.

[0060] In this way, by calculating the time difference between points in time that belong to the same number of periods in multiple periods of each signal related to the first signal 20S, the second signal 30S, and the reference signal BWS, and calculating the first time difference Δt1 and the second time difference Δt2 based on the average value of these time differences, the measurement accuracy of the wind speed V can be further improved.

[0061] <Wind speed measurement method> Next, an example of a wind speed measurement method according to the embodiment will be described with reference to Fig. 5. Fig. 5 is a flowchart showing an example of a wind speed measurement method according to the embodiment.

[0062] 5, in step S11, the first transceiver 20 transmits a first observation wave 20u1 to the flow path 10. Subsequently, in step S12, the second transceiver 30 transmits a second observation wave 30u1 to the flow path 10. Steps S11 and S12 may be performed at the same time. Alternatively, step S12 may be performed before step S11.

[0063] Next, in step S13, the measurement unit 40 detects a first point in time of the first signal 20S received by the second transceiver 30, and detects a second point in time of the second signal 30S received by the first transceiver 20.

[0064] Subsequently, in step S14, the measurement unit 40 calculates a first time difference Δt1, which is the time difference between the first time point and the reference time point, by referring to the reference time point of the reference signal BWS stored in the memory 442 of the control circuit 440. Furthermore, the measurement unit 40 calculates a second time difference Δt2, which is the time difference between the second time point and the reference time point, by referring to the reference time point of the reference signal BWS stored in the memory 442 of the control circuit 440.

[0065] Subsequently, in step S15, the measurement unit 40 measures the wind speed V from equation (4) using the first time difference Δt1 and the second time difference Δt2 calculated in step S14. Here, when measuring the wind speed V, the measurement unit 40 refers to the propagation distance L0 and propagation time T0 related to the reference wave BW stored in the memory 442 of the control circuit 440.

[0066] Through these steps, the wind speed sensor 1 measures the wind speed V in the flow path 10. However, the wind speed measurement method may include steps other than steps S11 to S15.

[0067] [Variations] Next, a wind speed sensor 1A according to a modified example of the embodiment will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view that schematically shows an example of a cross section of the wind speed sensor 1A according to the modified example taken along the XZ plane. In the wind speed sensor 1A according to the modified example, components that are substantially the same as those in the wind speed sensor 1 according to the embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0068] As shown in FIG. 6, the wind speed sensor 1A includes a flow path 10, a first transceiver 20, a second transceiver 30, and a measurement unit 40A. The wind speed sensor 1A according to the modification differs from the embodiment mainly in that the reference wave BW used to measure the wind speed V is a wave corrected by an ideal wave RW based on a design value. That is, the measurement unit 40A measures the wind speed V using information related to the correction result of the reference wave BW. The measurement unit 40A may be electrically connected to an external device 2. The external device 2 is, for example, an information processing device such as a computer. The theoretical wave RW will be described separately.

[0069] The reference wave BW may be corrected by the measurement unit 40A. In this case, the process of correcting the reference wave BW may be executed by, for example, a control circuit having a configuration similar to that of the control circuit 440 of the measurement unit 40 shown in FIG. 2. The reference wave BW may also be corrected by the external device 2. That is, information regarding the result of the correction of the reference wave BW processed by the external device 2 may be input to the measurement unit 40A.

[0070] The external device 2 may execute a simulation of the ideal wave RW and correct the reference wave BW based on the obtained simulation results. The external device 2 may also output information related to the simulation results of the ideal wave RW to the measurement section 40A. In this case, the measurement section 40A may correct the reference wave BW based on the information related to the simulation results of the ideal wave RW.

[0071] An example of the correction process for the reference wave BW will be described. As a premise, the ideal wave RW will be described. The ideal wave RW corresponds to at least one of a virtual first ultrasonic wave 20u transmitted from the virtual first transceiver 20 under reference conditions BC and received by the virtual second transceiver 30 via the flow path 10 when a virtual first transceiver 20 and a virtual second transceiver 30 are used, which are assumed to be installed according to the design values, and a virtual second ultrasonic wave 30u transmitted from the virtual second transceiver 30 under reference conditions BC and received by the virtual first transceiver 20 via the flow path 10. Note that "according to the design values" means that at least the position and orientation of the first transceiver 20, the position and orientation of the second transceiver 30, the distance between the first transceiver 20 and the bottom plate 52, and the distance between the second transceiver 30 and the bottom plate 52 are substantially identical to the design values. "According to the design values" is an example of "based on the design values."

[0072] In the simulation for obtaining the ideal wave RW, the external device 2 uses, for example, a preset propagation distance L ref and the speed of sound C ref Using the propagation time T ref Here, the propagation distance L of the ideal wave RWref An example of the propagation distance L of the ideal wave RW is the distance corresponding to the path of the virtual first ultrasonic wave 20u transmitted from the virtual first transceiver 20, reflected by the bottom plate 52, and then received by the virtual second transceiver 30, or the distance corresponding to the path of the second ultrasonic wave 30u transmitted from the virtual second transceiver 30, reflected by the bottom plate 52, and then received by the virtual first transceiver 20. That is, ref An example of the propagation distance of the ideal wave RW between the virtual first transceiver 20 and the virtual second transceiver 30 via the flow path 10 is given. Also, the propagation time T ref As an example of the propagation time T , there is a time period during which the virtual first ultrasonic wave 20u transmitted from the virtual first transceiver 20 is reflected by the bottom plate 52 and received by the virtual second transceiver 30 under the reference condition BC, or a time period during which the second ultrasonic wave 30u transmitted from the virtual second transceiver 30 is reflected by the bottom plate 52 and received by the virtual first transceiver 20 under the reference condition BC. That is, the propagation time T of the ideal wave RW ref An example of the propagation time of the ideal wave RW between the virtual first transceiver 20 and the virtual second transceiver 30 through the flow path 10 is given. In addition, the external device 2 calculates the sound velocity C of the ideal wave RW based on a preset virtual temperature in the flow path 10. ref An example of the virtual temperature is a reference temperature TE0.

[0073] Hereinafter, the measurement unit 40A measures the propagation distance L of the ideal wave RW. ref , propagation time T ref , and the speed of sound C ref The following describes a process of acquiring various pieces of information, including the above, from the external device 2 and correcting the propagation distances L0 and T0 of the reference wave BW. However, a similar correction process may be performed by the external device 2 or another external device.

[0074] A calculation example for correcting the propagation distances L0 and T0 of the reference wave BW will be described. The measurement unit 40A calculates the propagation time T0 of the reference wave BW and the propagation time T ref That is, the measurement unit 40A calculates the difference ΔT between the measured value and the actual value. ΔT=T0-T ref ···(5)

[0075] By the way, the propagation distance L0 of the reference wave BW is the propagation distance L of the ideal wave RW. ref , and the propagation distance L0 of the reference wave BW and the propagation distance L of the ideal wave RW ref Using the difference ΔL between these, it can be expressed as in equation (6). Note that the propagation distance L0 of the reference wave BW here is not based on the measurement results of the reference wave BW already stored in the measurement unit 40A, but is newly calculated in the following calculations. L0=L ref +ΔL (6)

[0076] Furthermore, using the relationship of equation (6), the propagation time T0 of the reference wave BW can be expressed as in equation (7). T0=[{(L ref +ΔL) / C0}] (7) Ideal wave propagation time T ref can be expressed by equation (8). T ref =L ref / C ref ···(8)

[0077] By transforming equation (5) using equations (7) and (8), equation (9) is obtained. The measurement unit 40A calculates ΔL using equation (9). ΔL=[ΔT-L ref {(1 / C0)-(1 / C ref )}]×C0···(9)

[0078] The measuring unit 40A substitutes ΔL obtained by equation (9) into equation (6) to obtain the propagation distance L0 of the reference wave BW. The obtained propagation distance L0 of the reference wave BW corresponds to the corrected propagation distance L0.

[0079] Furthermore, the measurement unit 40A calculates "L refThe propagation time T0 of the reference wave BW is calculated by substituting the corrected propagation distance L0 into equation (7) as the value of "+ΔL". The calculated propagation time T0 of the reference wave BW corresponds to the corrected propagation time T0.

[0080] In this way, the propagation distance L0 and propagation time T0 of the reference wave BW are calculated by multiplying the propagation distance L ref and propagation time T ref By correcting using this, it is possible to reduce measurement errors in the wind speed V caused by deviations from the design values ​​of the first transceiver 20 and the second transceiver 30, changes in the position and orientation of the first transceiver 20 and the second transceiver 30 over time after use, and differences in temperature within the flow path 10 that differ depending on the measurement timing of the reference wave BW.

[0081] The correction process of the reference wave BW may be performed in the measurement unit 40A or the external device 2 before or after shipping of the wind speed sensor 1A.

[0082] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention.

[0083] The aspects of the present invention are as follows, for example. <1> a flow path; a first transceiver that transmits a first ultrasonic wave to the flow path; a second transceiver that transmits a second ultrasonic wave to the flow path; A measurement unit; Equipped with When measuring wind speed, the first ultrasonic wave received by the second transmitter / receiver through the flow path is defined as a first observation wave; When measuring wind speed, the second ultrasonic wave received by the first transmitter / receiver through the flow path is set as a second observation wave, When at least one of the first ultrasonic wave received by the second transceiver through the flow path under reference conditions and the second ultrasonic wave received by the first transceiver through the flow path under the reference conditions is used as a reference wave, The measurement unit is a wind speed sensor that measures the wind speed in the flow path using a first time difference between the reference wave and the first observation wave and a second time difference between the reference wave and the second observation wave. <2> Among the reference waves, the first ultrasonic wave received by the second transceiver via the flow path is defined as a first reference wave, and the second ultrasonic wave received by the first transceiver via the flow path is defined as a second reference wave, the first time difference is a time difference between the first reference wave and the first observation wave, the second time difference is a time difference between the second reference wave and the second observation wave; The aforementioned <1> The wind speed sensor according to claim 1. <3> The reference condition includes a wind speed in the flow path being zero. The aforementioned <1> or the above <2> The wind speed sensor according to claim 1. <4> The wind speed in the flow path is V, a propagation distance of the reference wave between the first transceiver and the second transceiver via the flow path is defined as L0; a propagation time of the reference wave between the first transceiver and the second transceiver via the flow path is defined as T0; The first time difference is Δt1, When the second time difference is Δt2, The measurement unit Measure the wind speed in the flow path based on equation (1); The aforementioned <1> From the above <3> 10. The wind speed sensor according to claim 9, wherein: V=(L0 / 2)×[{1 / (Δt1+T0)}-{1 / (Δt2+T0)}]···(1) <5> The measurement unit storing the propagation distance L0 and the propagation time T0 of the reference wave measured under the reference condition in which the wind speed in the flow path is zero; The aforementioned <4> The wind speed sensor according to claim 1. <6> The propagation distance L0 and the propagation time T0 are related to the reference wave measured in advance under the reference conditions. The aforementioned <5> The wind speed sensor according to claim 1. <7> a signal related to the first observation wave received by the second transceiver is designated as a first signal; a signal related to the second observation wave received by the first transceiver is designated as a second signal; a signal related to the reference wave is used as a reference signal; The measurement unit detecting a first time point from the first signal; detecting a second point in time from the second signal; detecting a reference time point from the reference signal; calculating the first time difference based on a time difference between the first time point and the reference time point; calculating the second time difference based on the time difference between the second time point and the reference time point; The aforementioned <1> From the above <6> 10. The wind speed sensor according to claim 9, wherein: <8> The measurement unit detecting a time point at which a peak value in an n-th period (n is a natural number) of the first signal becomes zero as the first time point; a time point at which a peak value of the second signal in the n-th period becomes zero is detected as the second time point; A time point when the crest value of the reference signal in the n-th period becomes zero is detected as the reference time point. The aforementioned <7> The wind speed sensor according to claim 1. <9> The measurement unit Detecting m first time points at which the crest value of each period from the nth period to the [n+m]th period (where m is a natural number) becomes zero in the first signal; Detecting m second time points at which the crest value of each period from the nth period to the [n+m]th period in the second signal becomes zero; Detecting m reference time points at which the crest value of each period from the nth period to the [n+m]th period in the reference signal becomes zero; Calculating a time difference between the first time points and the reference time points in the same numbered cycles among the m first time points and the m reference time points, and calculating the first time difference based on an average value of the time differences; Calculating a time difference between the second time points and the reference time points in the same numbered cycles among the m second time points and the m reference time points, and calculating the second time difference based on an average value of the time differences. The aforementioned <7> or the above <8> The wind speed sensor according to claim 1. <10> The measurement unit detecting at least one of a plurality of time points at which the peak value of the reference signal becomes zero as the reference time point; Among a plurality of time points at which the crest value of the first signal becomes zero, the time point immediately before the reference time point is detected as the first time point; Among a plurality of time points at which the peak value of the second signal becomes zero, the time point immediately after the reference time point is detected as the second time point. The aforementioned <7> From the above <9> 10. The wind speed sensor according to claim 9, wherein: <11> The reference wave is a wave corrected by an ideal wave based on a design value. The aforementioned <1> From the above <10> 10. The wind speed sensor according to claim 9, wherein: <12> a propagation distance of the reference wave between the first transceiver and the second transceiver via the flow path is defined as L0; a propagation time of the reference wave between the first transceiver and the second transceiver via the flow path is defined as T0; The sound velocity of the reference wave is C0, In the ideal wave, the propagation distance between the virtual first transceiver based on the design value and the virtual second transceiver based on the design value via the flow path is defined as L ref year, The propagation time of the ideal wave between the virtual first transceiver and the virtual second transceiver via the flow path is T ref year, The sound speed of the ideal wave is C ref When you say, The measurement unit corrects the propagation distance L0 based on equation (2). The aforementioned <11> The wind speed sensor according to claim 1. Corrected L0=L ref +ΔL (2) Here, ΔL is calculated based on the formula (3). ΔL=[ΔT-L ref {(1 / C0)-(1 / C ref )}]×C0···(3) ΔT is calculated based on equation (4). ΔT = T0-T before correction ref ···(4) <13> The measurement unit The propagation time T0 is corrected based on the formula (2) using the corrected propagation distance L0. The aforementioned <12> The wind speed sensor according to claim 1. Corrected T0 = corrected L0 / C0 (5) <14> a flow path; a first transceiver that transmits a first ultrasonic wave to the flow path; a second transceiver that transmits a second ultrasonic wave to the flow path; A measurement unit; A wind speed measurement method using a wind speed sensor comprising: When measuring wind speed, a first ultrasonic wave is transmitted from the first transceiver and received by the second transceiver via the flow path, and the first ultrasonic wave is defined as a first observation wave; When measuring wind speed, a second ultrasonic wave is transmitted from the second transceiver and received by the first transceiver via the flow path, and the second ultrasonic wave is defined as a second observation wave; When at least one of the first ultrasonic wave received by the second transceiver through the flow path under reference conditions and the second ultrasonic wave received by the first transceiver through the flow path under the reference conditions is used as a reference wave, A wind speed measurement method in which the measurement unit measures the wind speed in the flow path using a first time difference between the reference wave and the first observation wave and a second time difference between the reference wave and the second observation wave. <15> a flow path; a first transceiver that transmits a first ultrasonic wave to the flow path; a second transceiver that transmits a second ultrasonic wave to the flow path; A measurement unit; A program that causes the measurement unit of the wind speed sensor to function as a means for measuring the wind speed in the flow path, When measuring wind speed, a first ultrasonic wave is transmitted from the first transceiver and received by the second transceiver via the flow path, and the first ultrasonic wave is defined as a first observation wave; When measuring wind speed, a second ultrasonic wave is transmitted from the second transceiver and received by the first transceiver via the flow path, and the second ultrasonic wave is defined as a second observation wave; When at least one of the first ultrasonic wave received by the second transceiver through the flow path under reference conditions and the second ultrasonic wave received by the first transceiver through the flow path under the reference conditions is used as a reference wave, A program that causes the measurement unit to function to measure the wind speed in the flow path using a first time difference between the reference wave and the first observation wave and a second time difference between the reference wave and the second observation wave. [Explanation of symbols]

[0084] 1,1A···Wind speed sensor, 20···First transmitter / receiver, 20u1···First observation wave, 20S···First signal, 30···Second transmitter / receiver, 30u1···Second observation wave, 30S···Second signal, 40,40A···Measurement unit, BC···Reference conditions, BW···Reference wave, BWS···Reference signal, L0···Propagation distance of reference wave, T0···Propagation time of reference wave, C0···Sound speed of reference wave, Δt1···Time difference between first observation wave and reference wave, Δt2···Time difference between second observation wave and reference wave, RW···Ideal wave, L ref ...propagation distance of ideal wave, T ref Ideal wave propagation time, C ref ... ideal wave speed of sound, V... wind speed

Claims

1. a flow path; a first transceiver that transmits a first ultrasonic wave to the flow path; a second transceiver that transmits a second ultrasonic wave to the flow path; A measurement unit; Equipped with When measuring wind speed, the first ultrasonic wave received by the second transmitter / receiver through the flow path is defined as a first observation wave; When measuring wind speed, the second ultrasonic wave received by the first transmitter / receiver through the flow path is defined as a second observation wave; When at least one of the first ultrasonic wave received by the second transceiver through the flow path under reference conditions and the second ultrasonic wave received by the first transceiver through the flow path under the reference conditions is defined as a reference wave, The measurement unit is a wind speed sensor that measures the wind speed in the flow path using a first time difference between the reference wave and the first observation wave and a second time difference between the reference wave and the second observation wave.

2. Among the reference waves, the first ultrasonic wave received by the second transceiver via the flow path is defined as a first reference wave, and the second ultrasonic wave received by the first transceiver via the flow path is defined as a second reference wave, the first time difference is a time difference between the first reference wave and the first observation wave, the second time difference is a time difference between the second reference wave and the second observation wave; The wind speed sensor according to claim 1 .

3. The reference condition includes a wind speed in the flow path being zero. The wind speed sensor according to claim 1 or 2.

4. The wind speed in the flow path is V, The propagation distance of the reference wave between the first transceiver and the second transceiver via the flow path is L ０ year, The propagation time of the reference wave between the first transceiver and the second transceiver via the flow path is T ０ year, The first time difference is Δt １ year, The second time difference is Δt ２ When The measurement unit Measure the wind speed in the flow path based on equation (1). The wind speed sensor according to claim 1 or 2. V=(L ０ / 2)×[{1 / (Δt １ +T ０ )}-{1 / (Δt ２ +T ０ )}]・・・(1)

5. The measurement unit The propagation distance L of the reference wave measured under the reference condition where the wind speed in the flow path is zero ０ and the propagation time T ０ Remember, The wind speed sensor according to claim 4.

6. The propagation distance L ０ and the propagation time T ０ is related to the reference wave measured in advance under the reference conditions, The wind speed sensor according to claim 5 .

7. a signal related to the first observation wave received by the second transceiver is designated as a first signal; a signal relating to the second observation wave received by the first transceiver is designated as a second signal; a signal related to the reference wave is used as a reference signal; The measurement unit Detecting a first time point from the first signal; detecting a second time point from the second signal; detecting a reference time point from the reference signal; calculating the first time difference based on a time difference between the first time point and the reference time point; calculating the second time difference based on a time difference between the second time point and the reference time point; The wind speed sensor according to claim 1 or 2.

8. The measurement unit detecting, as the first time point, a time point at which a peak value in an n-th period (n is a natural number) of the first signal becomes zero; a time point at which a peak value in the n-th period of the second signal becomes zero is detected as the second time point; a time point at which a peak value of the reference signal in the n-th period becomes zero is detected as the reference time point; The wind speed sensor according to claim 7.

9. The measurement unit detecting m first time points at which the crest value of each period from an nth period to an [n+m]th period (where m is a natural number) becomes zero in the first signal; detecting m second time points at which the crest value of each period from the nth period to the [n+m]th period in the second signal becomes zero; detecting m reference time points at which the crest value of each period from the nth period to the [n+m]th period in the reference signal becomes zero; calculating a time difference between the first time point and the reference time point in the same numbered cycle among the m first time points and the m reference time points, and calculating the first time difference based on an average value of the time differences; calculating a time difference between the second time points and the reference time points in the same numbered cycles among the m second time points and the m reference time points, and calculating the second time difference based on an average value of the time differences; The wind speed sensor according to claim 7.

10. The measurement unit detecting at least one of a plurality of time points at which the peak value of the reference signal becomes zero as the reference time point; Among a plurality of time points at which a peak value of the first signal becomes zero, the time point immediately before the reference time point is detected as the first time point; Among a plurality of time points at which the peak value of the second signal becomes zero, the time point immediately after the reference time point is detected as the second time point. The wind speed sensor according to claim 7.

11. The reference wave is a wave corrected by an ideal wave based on a design value. The wind speed sensor according to claim 1 or 2.

12. The propagation distance of the reference wave between the first transceiver and the second transceiver via the flow path is L ０ year, The propagation time of the reference wave between the first transceiver and the second transceiver via the flow path is T ０ year, The sound speed of the reference wave is C ０ year, In the ideal wave, the propagation distance between the virtual first transceiver based on the design value and the virtual second transceiver based on the design value via the flow path is defined as L ｒｅｆ year, In the ideal wave, the propagation time between the virtual first transceiver and the virtual second transceiver via the flow path is T ｒｅｆ year, The sound speed of the ideal wave is C ｒｅｆ When you say, The measurement unit calculates the propagation distance L based on the formula (2). ０ Correct the The wind speed sensor according to claim 11. Corrected L ０ =L ｒｅｆ +ΔL (2) Here, ΔL is calculated based on the formula (3). ΔL=[ΔT-L ｒｅｆ {(1 / C ０ )-(1 / C ｒｅｆ )}]×C ０ ・・・(3) ΔT is calculated based on equation (4). ΔT = T before correction ０ -T ｒｅｆ ...(4)

13. The measurement unit The propagation distance L after correction ０ Based on the formula (2) using ０ Correct the The wind speed sensor according to claim 12. Corrected T ０ = Corrected L ０ / C ０ ...(5)

14. a flow path; a first transceiver that transmits a first ultrasonic wave to the flow path; a second transceiver that transmits a second ultrasonic wave to the flow path; A measurement unit; A wind speed measurement method using a wind speed sensor comprising: When measuring wind speed, a first ultrasonic wave is transmitted from the first transceiver and received by the second transceiver via the flow path, and the first ultrasonic wave is defined as a first observation wave; When measuring wind speed, a second ultrasonic wave is transmitted from the second transceiver and received by the first transceiver via the flow path, and the second ultrasonic wave is defined as a second observation wave; When at least one of the first ultrasonic wave received by the second transceiver through the flow path under reference conditions and the second ultrasonic wave received by the first transceiver through the flow path under the reference conditions is defined as a reference wave, A wind speed measurement method in which the measurement unit measures the wind speed in the flow path using a first time difference between the reference wave and the first observation wave and a second time difference between the reference wave and the second observation wave.

15. a flow path; a first transceiver that transmits a first ultrasonic wave to the flow path; a second transceiver that transmits a second ultrasonic wave to the flow path; A measurement unit; A program that causes the measurement unit of the wind speed sensor to function as a means for measuring the wind speed in the flow path, When measuring wind speed, a first ultrasonic wave is transmitted from the first transceiver and received by the second transceiver via the flow path, and the first ultrasonic wave is defined as a first observation wave; When measuring wind speed, a second ultrasonic wave is transmitted from the second transceiver and received by the first transceiver via the flow path, and the second ultrasonic wave is defined as a second observation wave; When at least one of the first ultrasonic wave received by the second transceiver through the flow path under reference conditions and the second ultrasonic wave received by the first transceiver through the flow path under the reference conditions is defined as a reference wave, A program that causes the measurement unit to function to measure the wind speed in the flow path using a first time difference between the reference wave and the first observation wave and a second time difference between the reference wave and the second observation wave.

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