Ultrasonic anemometer and wind speed measuring method

Abstract

The present invention provides a compact and low-cost ultrasonic anemometer which receives ultrasonic waves after causing multiple reflections. An ultrasonic anemometer (100) comprises: a top plate (11) having a first surface (12) that extends along a first direction and a second direction intersecting the first direction; a first ultrasonic transceiver (31) and a second ultrasonic transceiver (32) mounted on the top plate (11) and disposed on both sides of the first surface (12) in the first direction; and a reflective plate disposed opposite to the first surface (12) in a third direction intersecting both the first and second directions, the reflective plate having a second surface (22) parallel to the first surface (12) and spaced therefrom by a first distance, and a third surface (23) located at a second distance from the first ultrasonic transceiver (31) in the third direction, the second distance being greater than the first distance.

Description

Ultrasonic anemometer and wind speed measurement method

[0001] The present disclosure relates to an ultrasonic anemometer and a method for measuring wind speed.

[0002] For example, a wind direction and speed measuring device is known that measures the wind direction and speed of a fluid to be measured based on the propagation time of ultrasonic waves transmitted and received between a pair of ultrasonic transmitters and receivers (see, for example, Patent Document 1). This wind direction and speed measuring device includes a housing in which a flow path through which the fluid to be measured flows is formed, and a pair of ultrasonic transmitters and receivers that are installed at a predetermined inclination relative to the flow path.

[0003] JP 2014-77643 A

[0004] Conventional technology faces challenges in improving wind direction accuracy. Ultrasonic anemometers, which rely on receiving ultrasonic waves after multiple reflections, are technically difficult to develop. Therefore, there is a demand for miniaturization and cost reduction in such ultrasonic anemometers.

[0005] An object of the present disclosure is to provide an ultrasonic anemometer that is small in size and low in cost, and receives ultrasonic waves after they are reflected multiple times.

[0006] The ultrasonic anemometer according to the present disclosure comprises a top plate having a first plane along a first direction and a second direction intersecting the first direction; a first ultrasonic transceiver and a second ultrasonic transceiver mounted on the top plate and arranged at a predetermined distance from the first plane in the first direction; and a reflector arranged opposite the first plane in a third direction intersecting the first and second directions, the reflector having a second plane parallel to the first plane and a third surface at a first distance from the first plane and a second distance longer than the first distance from the first ultrasonic transceiver and the second ultrasonic transceiver in the third direction.

[0007] The present disclosure can provide an ultrasonic anemometer that is small in size and low in cost, and receives ultrasonic waves after they are reflected multiple times.

[0008] 1 is a schematic perspective view illustrating an ultrasonic anemometer according to a first embodiment; FIG. 2 is a schematic cross-sectional view illustrating an ultrasonic anemometer according to the first embodiment; FIG. 3 is a plan view showing an example of an arrangement of reflectors and ultrasonic transmitters and receivers; FIG. 4 is a schematic view showing an example of a distance between a plurality of ultrasonic transmitters and receivers; FIG. 5 is a diagram showing an example of a vector indicating wind speed V, and an X-axis component and a Y-axis component of wind speed V; FIG. 6 is a schematic cross-sectional view illustrating an ultrasonic anemometer according to a comparative example; FIG. 7 is a plan view showing an example of an arrangement of reflectors and ultrasonic transmitters and receivers of an ultrasonic anemometer according to a second embodiment; FIG. 8 is a plan view showing an example of an arrangement of reflectors and ultrasonic transmitters and receivers of an ultrasonic anemometer according to a third embodiment; FIG. 9 is a plan view showing an example of an arrangement of reflectors and ultrasonic transmitters and receivers of an ultrasonic anemometer according to a fourth embodiment; FIG. 10 is a plan view showing an example of an arrangement of reflectors and ultrasonic transmitters and receivers of an ultrasonic anemometer according to a fifth embodiment; FIG. 11 is a schematic perspective view illustrating an ultrasonic anemometer according to a sixth embodiment; FIG. 12 is a plan view showing an example of an arrangement of reflectors and ultrasonic transmitters and receivers; and FIG. 13 is a block diagram showing an example of a hardware configuration of the ultrasonic anemometer according to the sixth embodiment. 14(a) is a graph illustrating waveforms of signals corresponding to the first and second observation waves, and FIG. 14(b) is a graph illustrating waveforms of signals corresponding to the third and fourth observation waves. FIG. 14(b) is a graph illustrating waveforms of signals corresponding to the first and second observation waves. FIG. 14(c) is a flowchart illustrating steps of a wind speed measurement method according to a sixth embodiment.

[0009] An ultrasonic anemometer according to an embodiment will be described below with reference to the accompanying drawings. In this specification and the drawings, substantially identical components may be designated by the same reference numerals to avoid redundant description. The terms "upper" and "lower" may be used in this specification. These refer to the "upper" and "lower" in the state shown in FIG. 2 , where the side where the top plate 11 is located in the Z-axis direction is referred to as "upper" and the side where the reflector plate 21 is located is referred to as "lower." The actual arrangement of the ultrasonic anemometer 100 is not limited to this. The "ultrasonic oscillator" may be referred to as an "ultrasonic transmitter / receiver," and the "ultrasonic oscillator" not only functions to emit ultrasonic waves but also functions as an ultrasonic receiver.

[0010] [Ultrasonic Anemometer 100 According to the First Embodiment] FIG. 1 is a schematic perspective view illustrating an ultrasonic anemometer 100 according to the first embodiment. FIG. 2 is a schematic cross-sectional view illustrating the ultrasonic anemometer 100 according to the first embodiment. FIG. 3 is a plan view illustrating an example of the arrangement of a reflector 21 and ultrasonic transmitters / receivers 31 to 34. FIG. 4 is a schematic view illustrating an example of distances Vx, Vy, Va, Vc, and Vd between the ultrasonic transmitters / receivers 31 to 34. Note that in each figure, the X-axis direction, Y-axis direction, and Z-axis direction, which are orthogonal to each other, may be illustrated. The X-axis direction, Y-axis direction, and Z-axis direction do not have to be orthogonal to each other. The X-axis direction, Y-axis direction, and Z-axis direction may be any direction. The X-axis direction is an example of a first direction. The Y-axis direction is an example of a second direction intersecting the first direction. The Z-axis direction is an example of a third direction intersecting the first direction and the second direction.

[0011] 1 and 2 is a wind direction and speed measurement device that measures the wind direction and speed of a fluid to be measured based on the propagation time of ultrasonic waves transmitted and received between an ultrasonic transmitter and an ultrasonic receiver. The ultrasonic anemometer 100 can determine wind speed from fluctuations in the speed of sound in air (approximately 340 m / s). The distance between the ultrasonic transmitter and the ultrasonic receiver is known, and the wind direction and speed of the fluid can be measured based on the difference in the propagation time of the ultrasonic waves.

[0012] As shown in Fig. 1, the ultrasonic anemometer 100 includes a first housing 10, a second housing 20, and multiple support columns 13. The first housing 10 and the second housing 20 are spaced apart in the Z-axis direction. The multiple support columns 13 extend in the Z-axis direction and support the first housing 10 relative to the second housing 20. The lower ends of the support columns 13 are fixed to the second housing 20, and the upper ends of the support columns 13 are fixed to the first housing 10. The first housing 10 mounts multiple ultrasonic transmitters / receivers 30 and a circuit board. Note that a cover that covers the top of the first housing 10 is not shown in Fig. 1.

[0013] 2 , the ultrasonic anemometer 100 includes a first housing 10 that also functions as a top plate 11, a plurality of ultrasonic transmitters and receivers 30, and a second housing 20 that also functions as a reflector 21. In the ultrasonic anemometer 100, a flow path 101 is formed in the space between the top plate 11 and the reflector 21. The ultrasonic anemometer 100 measures the wind direction and wind speed of a fluid flowing through the flow path 101.

[0014] [Top Plate 11] Specifically, the top plate 11 is provided on the first housing 10. The top plate 11 is arranged on the bottom of the first housing 10. The top plate 11 is, for example, disk-shaped. The top plate 11 is provided with a holder that holds multiple ultrasonic transceivers 30. The top plate 11 also has a surface (first plane 12) that reflects ultrasonic waves transmitted from the ultrasonic transceivers 30.

[0015] [First Plane 12] The top plate 11 has a first plane 12. The first plane 12 is a surface along the X-axis direction and the Y-axis direction. The first plane 12 is the lower surface of the top plate 11.

[0016] [Multiple Ultrasonic Transceivers 30] The multiple ultrasonic transceivers 30 include ultrasonic transceivers 31 to 34. The ultrasonic transceiver 31 is an example of a first ultrasonic transceiver, the ultrasonic transceiver 32 is an example of a second ultrasonic transceiver, the ultrasonic transceiver 33 is an example of a third ultrasonic transceiver, and the ultrasonic transceiver 34 is an example of a fourth ultrasonic transceiver. The multiple ultrasonic transceivers 30 are mounted on the top board 11. The ultrasonic transceiver 30 is an ultrasonic transmitting unit that transmits ultrasonic waves and an ultrasonic receiving unit that receives ultrasonic waves. The arrangement of the multiple ultrasonic transceivers 30 will be described later.

[0017] [Reflector 21] Specifically, the reflector 21 is provided on the top of the second housing 20. The reflector 21 is arranged to face the top plate 11 in the Z-axis direction. A space is formed between the top plate 11 and the reflector 21, through which the fluid to be measured can pass. The fluid to be measured may be, for example, air. The reflector 21 has a surface that reflects ultrasonic waves transmitted from the ultrasonic transmitter / receiver 30. The reflector 21 is an example of a bottom plate.

[0018] [Second Plane 22] The reflector 21 has a second plane 22 and a third plane 23. The second plane 22 may be the upper surface of the reflector 21. The second plane 22 faces the first plane 12 in the Z-axis direction and is a plane parallel to the second plane 22. "Parallel" includes "substantially parallel." The second plane 22 is a plane along the X-axis direction and the Y-axis direction. As shown in FIG. 3 , the second plane 22 is disposed in the center of the reflector 21 when viewed in the Z-axis direction. The reflector 21 has, for example, a circular shape. Furthermore, when viewed in the Z-axis direction, the second plane 22 includes an area overlapping with the first plane 12.

[0019] [Third Surface 23] The third surface 23 is formed around the second plane 22 when viewed in the Z-axis direction. The third surface 23 is formed to surround the second plane 22. The third surface 23 may be, for example, a conical inclined surface. As shown in FIG. 2 , in a cross section along the XZ plane, the third surface 23 includes an inclined surface inclined with respect to the second plane 22. The upper end of the third surface 23 is located closer to the second plane 22 in the X-axis direction than the lower end of the third surface 23. In the Z-axis direction, the lower end of the third surface 23 is located further outward than the upper end of the third surface 23. Here, the upper end is the end closest to the top plate 11 in the Z-axis direction, and the lower end is the end farthest from the top plate 11. The third surface 23 is inclined outward so as to face the opposite side from the second plane 22. The outer end of the third surface 23 is located lower than the inner end. "Facing outward" may also mean that the outer end is positioned lower than the inner end. "Downward" refers to the direction away from the top plate 11 in the Z-axis direction. The third surface 23 includes a position that overlaps with the ultrasonic transceivers 30 when viewed in the Z-axis direction. The third surface 23 includes a surface that is positioned directly below the multiple ultrasonic transceivers 30.

[0020] [First Distance H1] As shown in FIG. 2, the distance between the first plane 12 and the second plane 22 in the Z-axis direction is a first distance H1.

[0021] [Second distance H2] In the Z-axis direction, the distance between the ultrasonic transceiver 31 and the third surface 23 is the second distance H2. The second distance H2 is longer than the first distance H1. The second distance H2 is the distance from the ultrasonic transceiver 31 to a position P23a directly below the ultrasonic transceiver 31 as viewed in the Z-axis direction. The position P23a directly below is a position on the third surface 23.

[0022] [Arrangement of ultrasonic transceivers 31-34] Next, the arrangement of the ultrasonic transceivers 31-34 will be described with reference to Figure 3. The ultrasonic transceivers 31 and 32 are arranged spaced apart in the X-axis direction. The ultrasonic transceivers 33 and 34 are arranged spaced apart in the Y-axis direction. The multiple ultrasonic transceivers 31-34 are arranged at positions corresponding to the vertices 14c of the imaginary square 14 when viewed in the Z-axis direction. When viewed in the Z-axis direction, the multiple ultrasonic transceivers 31-34 are arranged outside the second plane 22. When viewed in the Z-axis direction, the ultrasonic transceivers 31-34 are arranged at positions overlapping the third plane 23. A portion of the multiple ultrasonic transceivers 31-34 may be arranged to overlap the second plane 22 when viewed in the Z-axis direction.

[0023] [Ultrasonic Transmission / Reception Paths] Next, ultrasonic transmission / reception paths in the ultrasonic anemometer 100 will be described with reference to Fig. 4. The ultrasonic anemometer 100 has diagonal transmission / reception paths UTx and UTy, and adjacent transmission / reception paths UTa, UTb, UTc, and UTd. The diagonal transmission / reception path UTx is a transmission / reception path between the ultrasonic transceiver 31 and the ultrasonic transceiver 32. When viewed in the Z-axis direction, the diagonal transmission / reception path UTx is formed along the X-axis direction. The diagonal transmission / reception path UTy is a transmission / reception path between the ultrasonic transceiver 33 and the ultrasonic transceiver 34. When viewed in the Z-axis direction, the diagonal transmission / reception path UTy is formed along the Y-axis direction.

[0024] The adjacent transmission / reception path UTa is the transmission / reception path between the ultrasonic transceiver 32 and the ultrasonic transceiver 33. The adjacent transmission / reception path UTb is the transmission / reception path between the ultrasonic transceiver 32 and the ultrasonic transceiver 34. The adjacent transmission / reception path UTc is the transmission / reception path between the ultrasonic transceiver 31 and the ultrasonic transceiver 34. The adjacent transmission / reception path UTd is the transmission / reception path between the ultrasonic transceiver 31 and the ultrasonic transceiver 33.

[0025] In the ultrasonic anemometer 100, as shown in FIG. 2, the first distance H, which is the distance between the first plane 12 and the second plane 22, is set so that the phase of the single reflected wave Uw1 matches the phase of the three reflected waves Uw3.

[0026] In the ultrasonic anemometer 100, the third surface 23 is formed so that the ultrasonic transceiver on the receiving side does not receive five reflected waves Uw5, seven reflected waves, nine reflected waves, or any more reflected waves.

[0027] The ultrasonic anemometer 100 can directly acquire vectors Vx and Vy on the diagonal transmission / reception paths UTx and UTy. This allows the ultrasonic anemometer 100 to detect wind direction and speed with high accuracy. As shown in FIG. 4 , the vector Vx is along the X-axis direction between the ultrasonic transceiver 31 and the ultrasonic transceiver 32. The vector Vy is along the Y-axis direction between the ultrasonic transceiver 33 and the ultrasonic transceiver 34.

[0028] The ultrasonic anemometer 100 can acquire vectors Va, Vb, Vc, and Vd on adjacent transmission / reception paths UTa, UTb, UTc, and UTd. The ultrasonic anemometer 100 can calculate vectors Vx and Vy from the vectors Va, Vb, Vc, and Vd. The ultrasonic anemometer 100 can avoid determining that there is no wind when there is strong wind across phases by comparing the vectors Vx and Vy acquired directly from the diagonal transmission / reception paths UTx and UTy with the vectors Vx and Vy acquired from the adjacent transmission / reception paths UTa, UTb, UTc, and UTd.

[0029] [X-Axis and Y-Axis Components of Wind Speed ​​V] Fig. 5 is a diagram showing an example of a vector indicating wind speed V, and the X-axis and Y-axis components of wind speed V. In the diagonal transmission / reception paths, as shown in Fig. 5, the ultrasonic anemometer 100 calculates wind speed V and wind direction using vectors Vx and Vy. In the adjacent transmission / reception path, for example, vector Vx of the X-axis component is calculated from vectors Va to Vd. For example, Vx = {(Vc) ２ +(Vd) ２} １／２ ×COSθ ｃｄ , or Vx = {(Va)２ +(Vb) ２} １／２ ×COSθ ａｂ Similarly, the Y-axis component vector Vy is calculated from the vectors Va to Vd. Here, θ ｃｄ =tan －１ (Vc / Vd)-π / 4, and θ ａｂ =tan －１ (Va / Vb)-π / 4. For example, Vy={(Vd) ２ + (Va) ２} １／２ ×COSθ ｄａ , or Vy = {(Vb) ２ +(Vc) ２} １／２ ×COSθ ｂｃ Here, θ ｄａ =tan －１ (Vd / Va)-π / 4, and θ ｂｃ =tan －１ (Vb / Vc)-π / 4 Then, the wind speed V and wind direction are calculated from the vectors Vx and Vy in the same manner as in FIG.

[0030] [Single Reflected Wave] For example, in the diagonal transmission / reception path UTx, a single reflected wave Uw1 is transmitted from the ultrasonic transceiver 31, reflected at a point P22a on the second plane 22, and received by the ultrasonic transceiver 32. In Fig. 2, the single reflected wave Uw1 is indicated by a solid line.

[0031] [Three Reflected Waves] For example, in the diagonal transmission / reception path UTx, three reflected waves Uw3 are transmitted from the ultrasonic transceiver 31, reflected at point P22b on the second plane 22, reflected at point P12a on the first plane 12, and reflected at point P22c on the second plane 22, and are received by the ultrasonic transceiver 32. In Fig. 2, the three reflected waves Uw3 are indicated by dashed lines.

[0032] When it is desired to obtain one reflected wave Uw1 and three reflected waves Uw3 in the ultrasonic anemometer 100, once the distance between the ultrasonic transceiver 31 and the ultrasonic transceiver 32 is determined, the first distance H between the top plate 11 and the second plane 22 is determined.

[0033] [Five or More Reflected Waves] For example, five reflected waves Uw5 are transmitted from the ultrasonic transceiver 31, reflected at point P23b on the third surface 23, and directed toward the outside of the ultrasonic anemometer 100. After reflecting from the third surface 23, the five reflected waves do not strike the top plate 11. After reflecting from the third surface 23, five or more reflected waves head toward the outside of the ultrasonic anemometer 100 and do not strike the top plate 11. In FIG. 2 , the five reflected waves Uw5 are indicated by dashed lines. As will be described later, the five reflected waves include reflected waves that are reflected five times and reach the ultrasonic transceiver 32, and also include reflected waves that reach the ultrasonic transceiver 32 if a plane is formed at the same height (position in the Z-axis direction) as the second plane 22. FIG. 2 illustrates five reflected waves Uw5 that do not reach the ultrasonic transceiver 32, while FIG. 6 illustrates reflected waves Uw5 that reach the ultrasonic transceiver 32.

[0034] Fig. 6 is a schematic cross-sectional view illustrating an ultrasonic anemometer 100G according to a comparative example. The ultrasonic anemometer 100G according to the comparative example shown in Fig. 6 differs from the ultrasonic anemometer 100 according to the first embodiment shown in Fig. 2 in that the area of ​​the second flat surface 22G is large, and ultrasonic waves that are reflected five or more times between the first flat surface 12 of the top panel 11 and the second flat surface 22G of the reflecting plate 21G (reflected wave Uw5) reach the ultrasonic transceiver 32.

[0035] For example, if the area of ​​the second plane 22G parallel to the first plane 12 is large and extends below the ultrasonic transceiver 31 and the ultrasonic transceiver 32, the reflected wave Uw5 that reflects five or more times between the first plane 12 and the second plane 22G will also reach the ultrasonic transceiver 32.

[0036] Here, if the propagation distance is increased, i.e., if the first distance H1 can be increased, ultrasonic waves that reflect five or more times will be attenuated and will not reach the ultrasonic transceiver 32. However, if the ultrasonic anemometer is made smaller, the first distance H1 cannot be increased, and the reflected wave Uw5 that reflects five or more times will also reach the ultrasonic transceiver 32. Therefore, the third surface 23 is set so that the reflected wave Uw5 that reflects five or more times will be directed outside the ultrasonic anemometer 100. In the ultrasonic anemometer 100, the area of ​​the second plane 22 parallel to the first plane 12 is made smaller than the second plane 22G so that the ultrasonic wave (reflected wave Uw5) does not reflect five or more times and reach the ultrasonic transceiver 32, and the third surface 23 (see FIGS. 1 and 2 ) is set so that the reflected wave Uw5 that reflects five or more times will be directed outside the ultrasonic anemometer 100.

[0037] 1 and 2 is required at least in the Z-axis direction below the ultrasonic transceiver 31. In this embodiment, the third surface 23 is set so that five or more reflected waves Uw5 are directed toward the outside of the ultrasonic anemometer 100, but the third surface 23 may be set so that three or more reflected waves Uw3 are directed toward the outside of the ultrasonic anemometer 100.

[0038] In the ultrasonic anemometer 100, the first distance H1 between the top plate 11 and the second plane 22 and the second distance H2 between the ultrasonic transmitter / receiver 31 and the third plane 23 are appropriately set in the Z-axis direction, so that the diagonal transmission / reception paths UTx and UTy and the adjacent transmission / reception paths UTa, UTb, UTc, and UTd can be secured simultaneously. The "first ultrasonic wave 31x" and other terms will be explained later.

[0039] 3 , the distance between the ultrasonic transceiver 31 and the ultrasonic transceiver 32 in the X-axis direction is the third distance D3 between the opposing sensors. The distance between the ultrasonic transceiver 33 and the ultrasonic transceiver 34 in the Y-axis direction is the third distance D3 between the opposing sensors. The third distance D3 between the opposing sensors may be, for example, 23.3 mm.

[0040] [Fourth Distance D4 Between Adjacent Sensors] The distance between the ultrasonic transceiver 31 and the ultrasonic transceiver 33 is the fourth distance D4. The distance between the ultrasonic transceiver 31 and the ultrasonic transceiver 34 is the fourth distance D4. The distance between the ultrasonic transceiver 32 and the ultrasonic transceiver 33 is the fourth distance D4. The distance between the ultrasonic transceiver 32 and the ultrasonic transceiver 34 is the fourth distance D4. The fourth distance D4 between adjacent sensors may be, for example, 16.4 mm. In other words, the fourth distance D4 is shorter than the third distance D3.

[0041] The first reflected wave Uw1 and the third reflected wave Uw3 have different measurement lines and different propagation distances, and therefore arrive at the receiving sensor with a propagation time difference. The receiving sensor is one of the ultrasonic transceivers 31 to 34 that receives ultrasonic waves. In the ultrasonic anemometer 100, the first distance H1 is set so that the first reflected wave Uw1 and the third reflected wave Uw3 are in positive phase. If the first reflected wave Uw1 and the third reflected wave Uw3 are in opposite phase, the signal from the first reflected wave Uw1 and the signal from the third reflected wave Uw3 cancel each other out, and no signal can be obtained.

[0042] [Reaching distance A1 of one reflected wave Uw1 of the opposing path and reaching distance A3 of three reflected waves Uw3] The opposing paths are diagonal transmission / reception paths UTx and UTy. The reaching distance A1 of one reflected wave Uw1 of the opposing path is the distance from when the ultrasonic wave (first ultrasonic wave 31x) transmitted from the ultrasonic transceiver 31 is reflected once by the second plane 22 to when it reaches the ultrasonic transceiver 32, as shown in FIG.

[0043] The arrival time [s] of n reflected waves, the arrival distance [m] of n reflected waves, and the speed of sound [m / s] satisfy the following relationship.

[0044] Arrival time of n reflected waves [s]=Arrival distance of n reflected waves [m] / Speed ​​of sound [m / s] Here, the speed of sound c at 15 degrees is 340.65 [m / s].

[0045] The reach distance A1 [m] of one reflected wave Uw1 can be calculated by the following formula (1): The reach distance A1 can be expressed by the following formula (1) using the first distance H1 and the third distance D3.

[0046] The reach distance A3 [m] of the three reflected waves Uw3 can be calculated by the following formula (2): The reach distance A3 can be expressed by the following formula (2) using the first distance H1 and the third distance D3.

[0047] Here, when the first distance H1 in the formulas (1) and (2) is a variable, the difference between the arrival time of the single reflected wave Uw1 and the arrival time of the three reflected waves Uw3 varies simultaneously.

[0048] For example, when the resonant frequency of the ultrasonic transmitters and receivers 31 to 34 is 40 kHz, one period is 25 μs. In the ultrasonic anemometer 100, the first distance H1 is set so that the difference between the arrival time of the first reflected wave Uw1 and the arrival time of the three reflected waves Uw3 is a multiple of 25 μs. With the ultrasonic anemometer 100 in which the distance between the first plane 12 and the second plane 22 is the first distance H1, the first reflected wave Uw1 and the three reflected waves Uw3 can be set to be in positive phase.

[0049] For example, the first distance H1 may be 10.7 mm. Entering H1 = 10.7 mm into the above formulas (1) and (2) and checking the calculations reveals that the arrival time of one reflected wave Uw1 is 92.65 μs, and the arrival time of three reflected waves Uw3 is 142.91 μs. The difference between the arrival time of one reflected wave Uw1 and the arrival time of three reflected waves Uw3 is 50.26 μs, resulting in a positive phase with a delay of two periods.

[0050] [Reaching distance B1 of one reflected wave of adjacent paths and reaching distance B3 of three reflected waves] As shown in Fig. 4, adjacent paths are adjacent transmission / reception paths UTa, UTb, UTc, and UTd. The reaching distance B1 of one reflected wave of adjacent paths is the distance from when the ultrasonic wave (third ultrasonic wave 31c) transmitted from the ultrasonic transceiver 31 is reflected once by the second plane 22 to when it reaches the ultrasonic transceiver 33.

[0051] The reach distance B1 [m] of one reflected wave of an adjacent path can be calculated by the following formula (3): The reach distance B1 can be expressed by the following formula (3) using the first distance H1 and the fourth distance D4.

[0052]

[0053] The reach distance B3 [m] of the three reflected waves of the adjacent paths can be calculated by the following formula (4): The reach distance B3 can be expressed by the following formula (4) using the first distance H1 and the fourth distance D4.

[0054]

[0055] For example, when the fourth distance D4 between adjacent sensors is 16.4 mm and the first distance H1 is 9.9 mm, the travel distance B1 of a single reflected wave of an adjacent path is 25.7 mm. Similarly, the travel distance of an ultrasonic wave transmitted from the ultrasonic transceiver 31, reflected three times by the second plane 22, and then reaching the ultrasonic transceiver 34 is 125.8 mm. Furthermore, the travel time of an ultrasonic wave transmitted from the ultrasonic transceiver 32, reflected once by the second plane 22, and then reaching the ultrasonic transceiver 33 is 75.47 μs, and the travel time of an ultrasonic wave transmitted from the ultrasonic transceiver 32, reflected three times by the second plane 22, and then reaching the ultrasonic transceiver 33 is 125.82 μs. The difference between the travel time of a single reflected wave and the travel time of three reflected waves is 50.35 μs, resulting in a positive phase with a delay of two periods.

[0056] According to this calculation, the calculated optimum first distance H1 calculated using the fourth distance D4 between adjacent sensors may be 9.9 mm.

[0057] To achieve both the diagonal transmission / reception paths UTx and UTy and the adjacent transmission / reception paths UTa, UTb, UTc, and UTd, the first distance H1 between the first plane 12 and the second plane 22 may be a value between 10.7 mm and 9.9 mm. To achieve both the diagonal transmission / reception paths UTx and UTy and the adjacent transmission / reception paths UTa, UTb, UTc, and UTd, the first distance H1 may be, for example, 10.3 mm. Here, the positive phase includes not only cases where the wavelengths L of the ultrasonic waves reaching the ultrasonic transmitter / receiver are perfectly aligned, but also cases where the wavelengths L are shifted by up to ¼ of one period. This is because at least one reflected wave Uw1 and three reflected waves Uw3 can be received without attenuation due to interference. Here, if the first distance H1 is 10.3 mm, it can be said that the one reflected wave and the three reflected waves from the diagonal transmission / reception paths UTx and UTy and the adjacent transmission / reception paths UTa, UTb, UTc, and UTd are in positive phase. Achieving both the diagonal transmission / reception paths UTx and UTy and the adjacent transmission / reception paths UTa, UTb, UTc, and UTd means that the one and three reflected waves arrive on both the diagonal transmission / reception paths and the adjacent transmission / reception paths.

[0058] The optimal first distance H1 can also be applied to one, three, and five reflected waves. However, including up to five reflected waves increases design constraints. Therefore, the third surface 23 is set so that five or more reflected waves are directed to the outside of the ultrasonic anemometer 100. This makes it easier to determine the first distance H1 in the ultrasonic anemometer 100 than in the ultrasonic anemometer 100G according to the comparative example, in which five or more reflected waves reach the ultrasonic transceiver 32, thereby simplifying the design of the ultrasonic anemometer 100.

[0059] [Operation and Effect of Ultrasonic Anemometer 100 According to First Embodiment] The ultrasonic anemometer 100 according to the first embodiment includes a top plate 11 having a first plane 12 along the X-axis direction (first direction) and the Y-axis direction (second direction intersecting the first direction), an ultrasonic transceiver (first ultrasonic transceiver) 31 and an ultrasonic transceiver (second ultrasonic transceiver) 32 mounted on the top plate 11 and disposed a predetermined distance from the first plane 12 in the X-axis direction, and a reflector 21 disposed opposite the first plane 12 in the Z-axis direction (third direction), having a second plane 22 parallel to the first plane 12 and a position overlapping with the ultrasonic transceiver 31 in the Z-axis direction, and a third surface 23 whose distance from the ultrasonic transceiver 31 in the Z-axis direction is a second distance H2 longer than the first distance H1. Note that "parallel" includes "substantially parallel."

[0060] In the ultrasonic anemometer 100, ultrasonic waves transmitted from the ultrasonic transceiver 31 are reflected by the second plane 22 and reach the ultrasonic transceiver 32, thereby realizing a transmission / reception path using a single reflected wave Uw1. Furthermore, in the ultrasonic anemometer 100, ultrasonic waves transmitted from the ultrasonic transceiver 31 are reflected by the second plane 22, which in turn is reflected by the first plane 12, and then reflected again by the second plane 22 and reaches the ultrasonic transceiver 32, thereby realizing a transmission / reception path using three reflected waves Uw3. The first reflected wave Uw1 and the third reflected wave Uw3 have different measurement lines and different propagation distances, and therefore arrive at the receiving ultrasonic transceivers 31 and 32 with different time differences. The ultrasonic anemometer 100 can calculate the wind speed of the fluid being measured using round-trip path time difference (phase difference) determination. The ultrasonic anemometer 100 can provide an ultrasonic anemometer that is compact and low-cost, and receives ultrasonic waves by reflecting them multiple times.

[0061] In the ultrasonic anemometer 100, the third surface 23 is arranged opposite the ultrasonic transceiver 31 and the second ultrasonic transceiver 32 in the Z-axis direction, and includes the third surface 23 which is an inclined surface inclined relative to the second plane 22, and the third surface 23 is inclined so as to face the opposite side to the second plane 22.

[0062] In the ultrasonic anemometer 100 configured as described above, the third surface 23 is formed as an inclined surface that slopes away from the second plane 22, so that part of the ultrasonic waves transmitted from the ultrasonic transceiver 32 are reflected by the third surface 23 and travel outside the ultrasonic anemometer 100. The ultrasonic anemometer 100 can achieve an ultrasonic transmission / reception path that does not involve five reflected waves. The inclined surface may include a linear surface or a curved surface, for example, in a cross section along the Z-axis direction. The inclined surface may be any surface that allows the reflected waves reflected by the inclined surface to travel outside the ultrasonic anemometer 100.

[0063] The ultrasonic anemometer 100 further includes an ultrasonic transmitter / receiver (third ultrasonic transmitter / receiver) 33 and an ultrasonic transmitter / receiver (fourth ultrasonic transmitter / receiver) 34 mounted on the top plate 11 and arranged on both sides of the first plane 12 in the Y-axis direction, and the ultrasonic transmitter / receivers 31 to 34 are arranged at positions corresponding to the vertices 14c of the virtual square 14 when viewed in the Z-axis direction, and the second plane 22 forms a circle when viewed in the Z-axis direction.

[0064] This ultrasonic anemometer 100 can realize a diagonal transmission / reception path UTx along the X-axis direction, a diagonal transmission / reception path UTy along the Y-axis direction, and adjacent transmission / reception paths UTa, UTb, UTc, and UTd along each side of an imaginary rectangle. The ultrasonic anemometer 100 can receive ultrasonic waves propagated along these transmission / reception paths and calculate a vector Vx along the X-axis direction, a vector Vy along the Y-axis direction, and vectors Va, Vb, Vc, and Vd along each side of the imaginary rectangle 14. The ultrasonic anemometer 100 can measure the wind direction and wind speed of the fluid being measured using these vectors Vx, Vy, Va, Vb, Vc, and Vd.

[0065] Furthermore, in the ultrasonic anemometer 100, when the first distance is H1, the third distance between the ultrasonic transceivers 31 and 32 is D3, and the wavelength of the ultrasonic waves transmitted from the ultrasonic transceivers 31 and 32 is L, the following equations (5) and (6) are satisfied. Here, the reason why the range of the absolute value A in equation (6) is given some flexibility is because the positive phase of the ultrasonic waves is not only permitted to perfectly match an integer multiple of the wavelength L of the ultrasonic waves reaching the ultrasonic transceivers, but also to include a deviation of ¼ of the wavelength L.

[0066]

[0067] Here, n is a natural number.

[0068] The ultrasonic anemometer 100 further includes an ultrasonic transmitter / receiver 33 and an ultrasonic transmitter / receiver 34 mounted on the top plate 11 and arranged on both sides of the first plane 12 in the Y-axis direction, and satisfies the following equations (7) and (8) when a fourth distance between the ultrasonic transmitter / receiver 31 and the ultrasonic transmitter / receiver 34 is D4. Here, the wavelength L in equation (8) has a range because a positive phase does not mean that the wavelengths of the ultrasonic waves reaching the ultrasonic transmitter / receiver are perfectly identical, but also includes cases where the wavelengths are shifted by up to ¼.

[0069]

[0070] Here, n is a natural number.

[0071] Here, when the resonant frequency of the ultrasonic transmitter / receiver is 40 kHz and the speed of sound is 340.65 m / sec, the wavelength L is 8.5 mm. If the third distance D3 between the opposing sensors is 23.3 mm, the fourth distance D4 between adjacent sensors is 16.4 mm, the height H1 is 10.7 mm, and the speed of sound is 340.65 m / sec, the absolute value of A |A| calculated using the above formula (5) is 17.1 mm, and the absolute value of B |B| calculated using the above formula (7) is 18.9 mm. Here, since twice the wavelength L is 17.0 mm (when the natural number n is 2), both |A| and |B| are greater than or equal to 0.75L × 2 and less than or equal to 1.25L × 2. In this case, both the above formulas (6) and (8) are simultaneously satisfied.

[0072] [Ultrasonic anemometer 100B according to a second embodiment] Next, an ultrasonic anemometer 100B according to a second embodiment will be described. Fig. 5 is a plan view showing the arrangement of the reflector 21B and the ultrasonic transmitters / receivers 31 to 34 of the ultrasonic anemometer 100B according to the second embodiment. The ultrasonic anemometer 100B shown in Fig. 7 differs from the ultrasonic anemometer 100 shown in Fig. 3 in that it includes a reflector 21B instead of the reflector 21, and the shape of the second plane 22B is different. Note that in the description of the 100B according to the second embodiment, descriptions similar to those of the ultrasonic anemometer 100 according to the first embodiment described above may be omitted.

[0073] The ultrasonic anemometer 100B includes a reflector 21B, and a second plane 22B is formed on the reflector 21B. The second plane 22B is formed to form a cross shape when viewed in the Z-axis direction. The second plane 22B includes regions 24a, 24b, 24c, 24d, and 24e. The region 24a is rectangular and is located at the center of the second plane 22B. The diagonals of the region 24a are arranged along the X-axis direction and the Y-axis direction. The regions 24b to 24e are rectangular and are formed to extend outward from each side of the region 24a. For example, the region 24b is formed between the ultrasonic transceiver 32 and the ultrasonic transceiver 33. The region 24c is formed between the ultrasonic transceiver 32 and the ultrasonic transceiver 34. The region 24d is formed between the ultrasonic transceiver 34 and the ultrasonic transceiver 31. The region 24 e is formed between the ultrasonic transceiver 31 and the ultrasonic transceiver 33 .

[0074] The ultrasonic anemometer 100B according to the second embodiment also achieves the same effects as the ultrasonic anemometer 100 according to the first embodiment. Furthermore, the adjacent transmission / reception paths UTa, UTb, UTc, and UTd can reflect ultrasonic waves at their outwardly protruding portions (regions 24b, 24c, 24d, and 24e). As a result, wind speed can be calculated using not only the transmission / reception paths UTx and UTy but also the transmission / reception paths UTa, UTb, UTc, and UTd, improving the accuracy of the wind speed. The second plane 22B may be cross-shaped.

[0075] [Ultrasonic anemometer 100C according to the third embodiment] Next, an ultrasonic anemometer 100C according to the third embodiment will be described. Fig. 8 is a plan view showing the arrangement of the reflector 21C and the ultrasonic transmitters and receivers 31 to 34 of the ultrasonic anemometer 100C according to the third embodiment. The ultrasonic anemometer 100C shown in Fig. 8 differs from the ultrasonic anemometer 100 shown in Fig. 3 in that it includes a reflector 21C instead of the reflector 21, and the shape of the second plane 22C is different. Note that in the description of the 100C according to the third embodiment, descriptions that are the same as those of the ultrasonic anemometers 100 and 100B according to the above embodiments may be omitted.

[0076] The ultrasonic anemometer 100C includes a reflector 21C, and a second plane 22C is formed on the reflector 21C. The second plane 22C is formed to form a cross shape (approximately a cross shape) when viewed in the Z-axis direction. The second plane 22C includes regions 24a, 24b, 24c, 24d, and 24e. The region 24a is rectangular and located at the center of the second plane 22C. The diagonals of the region 24a are aligned along the X-axis and Y-axis directions. The regions 24b to 24e are semicircular and extend outward from each side of the region 24a. For example, the region 24b is formed between the ultrasonic transceiver 32 and the ultrasonic transceiver 33. The region 24c is formed between the ultrasonic transceiver 32 and the ultrasonic transceiver 34. The region 24d is formed between the ultrasonic transceiver 34 and the ultrasonic transceiver 31. The region 24e is formed between the ultrasonic transceiver 31 and the ultrasonic transceiver 33. The second plane 22C is an example of a cross shape with an arc-shaped tip.

[0077] The ultrasonic anemometer 100C according to the third embodiment also achieves the same effects as the ultrasonic anemometers 100 according to the first and second embodiments. The shapes of the regions 24b to 24e are not limited to semicircular shapes, and may be semi-elliptical, trapezoidal, or other shapes. It is sufficient that the second plane 22C is located at least between adjacent ultrasonic transmitters / receivers, and by making the remaining portions the third plane 23, unwanted reflections can be reduced, thereby reducing noise.

[0078] [Ultrasonic Anemometer 100D According to Fourth Embodiment] Next, an ultrasonic anemometer 100D according to a fourth embodiment will be described. FIG. 9 is a plan view showing the arrangement of the reflector 21D and the ultrasonic transmitters / receivers 31 to 34 of the ultrasonic anemometer 100D according to the fourth embodiment. The ultrasonic anemometer 100D shown in FIG. 9 differs from the ultrasonic anemometer 100 shown in FIG. 3 in that it includes a reflector 21D instead of the reflector 21, and that a portion of the second plane 22D is disposed directly below the ultrasonic transmitters / receivers 31 to 34 when viewed in the Z-axis direction. Note that in the description of the 100D according to the fourth embodiment, descriptions similar to those of the ultrasonic anemometer 100 according to the above embodiments may be omitted.

[0079] The ultrasonic anemometer 100D includes a reflector 21D, and a second plane 22D is formed on the reflector 21D. The second plane 22D is formed to form a circle when viewed in the Z-axis direction. In the Z-axis direction, at least a portion of the second plane 22D is disposed directly below the ultrasonic transmitters / receivers 31 to 34. In the Z-axis direction, a portion of the second plane 22D near the outer periphery is disposed so as to overlap the ultrasonic transmitters / receivers 31 to 34.

[0080] The ultrasonic anemometer 100D according to the fourth embodiment also achieves the same effects as the ultrasonic anemometer 100 according to the above embodiment. A portion of the second plane 22D may be located directly below the ultrasonic transceivers 31 to 34. As a result, the range of the second plane 22D within which ultrasonic waves transmitted from the ultrasonic transceiver 30 can be reflected the first time can be widened. For example, in order for ultrasonic waves reflected three times to reach the ultrasonic transceiver 31 and the ultrasonic transceiver 34, the second plane 22D must be located at a position one-fourth the fourth distance D4 between adjacent sensors. However, there is a limit to how small the ultrasonic transceiver 30 can be. Therefore, by locating a portion of the second plane 22D directly below the ultrasonic transceiver 30, the fourth distance D4 between adjacent sensors can be shortened, thereby enabling the ultrasonic anemometer 100D to be miniaturized.

[0081] [Ultrasonic Anemometer 100E According to a Fifth Embodiment] Next, an ultrasonic anemometer 100E according to a fifth embodiment will be described. FIG. 9 is a plan view showing the arrangement of the reflector 21E and the ultrasonic transmitters / receivers 31 to 34 of the ultrasonic anemometer 100E according to the fifth embodiment. The ultrasonic anemometer 100E shown in FIG. 10 differs from the ultrasonic anemometer 100 shown in FIG. 3 in that it includes a reflector 21E instead of the reflector 21, and the shape of the second plane 22E is different. A portion of the second plane 22E is disposed directly below the ultrasonic transmitters / receivers 31 to 34. Note that in the description of the 100E according to the fifth embodiment, descriptions similar to those of the ultrasonic anemometer 100 according to the above embodiments may be omitted.

[0082] The ultrasonic anemometer 100E includes a reflector 21E, and a second plane 22E is formed on the reflector 21E. The second plane 22E is formed to form a cross shape when viewed in the Z-axis direction. The second plane 22E includes regions 24a, 24b, 24c, 24d, and 24e. Region 24a is rectangular and is located at the center of the second plane 22E. The diagonals of region 24a are arranged along the X-axis direction and the Y-axis direction. Regions 24b to 24e are rectangular and are formed to extend outward from each side of region 24a. For example, region 24b is formed between the ultrasonic transceiver 32 and the ultrasonic transceiver 33. Region 24c is formed between the ultrasonic transceiver 32 and the ultrasonic transceiver 34. Region 24d is formed between the ultrasonic transceiver 33 and the ultrasonic transceiver 34. Region 24e is formed between the ultrasonic transceiver 31 and the ultrasonic transceiver 33. The region 24a is an example of a first region, and the regions 24b to 24e are examples of second regions.

[0083] In the Z-axis direction, at least a portion of the second plane 22E is disposed directly below the ultrasonic transmitters / receivers 31 to 34. In the Z-axis direction, a portion of the second plane 22E is disposed so as to overlap the ultrasonic transmitters / receivers 31 to 34.

[0084] Parts of regions 24a, 24d, and 24e are disposed directly below ultrasonic transceiver 31. Parts of regions 24a, 24b, and 24c are disposed directly below ultrasonic transceiver 32. Parts of regions 24a, 24b, and 24e are disposed directly below ultrasonic transceiver 33. Parts of regions 24a, 24c, and 24d are disposed directly below ultrasonic transceiver 34. In the Z-axis direction, at least a part of second plane 22E is disposed so as to overlap with ultrasonic transceivers 31 to 34.

[0085] The ultrasonic anemometer 100E according to the fifth embodiment also achieves the same effects as the ultrasonic anemometer 100 according to the above embodiments. A portion of the second plane 22E may be located directly below the ultrasonic transceivers 31 to 34. As a result, the range of the second plane 22E over which ultrasonic waves transmitted from the ultrasonic transceiver 30 can be reflected the first time can be widened, even in adjacent transmission / reception paths. For example, in order for three reflected waves of ultrasonic waves to reach the ultrasonic transceiver 31 and the ultrasonic transceiver 34, the second plane 22E must be located at ¼ of the fourth distance D4 between adjacent sensors. However, there is a limit to how small the ultrasonic transceiver 30 can be. Therefore, by locating a portion of the second plane 22E directly below the ultrasonic transceiver 30, the fourth distance D4 between adjacent sensors can be shortened, thereby enabling the ultrasonic anemometer 100E to be miniaturized. The tip of the cross-shaped second plane 22E may be arc-shaped, as shown in FIG. 8 .

[0086] [First Slope 25] The reflector 21E may also have a first slope 25 formed around the second flat surface 22E and inclined relative to the second flat surface 22E. The first slope 25 is inclined outward so as to face the side opposite the second flat surface 22E. The surface of the first slope 25 may also be subjected to an anti-reflection treatment to suppress reflection of ultrasonic waves. An example of the anti-reflection treatment is a textured surface. A portion of the first slope 25 is disposed directly below the ultrasonic transmitter / receivers 31 to 34.

[0087] [Third Surface 23] The third surface 23 is formed around the second plane 22E and the first inclined surface 25 when viewed in the Z-axis direction. The third surface 23 is formed to surround the second plane 22E and the first inclined surface 25. The third surface 23 is an example of a second inclined surface. The third surface 23 is inclined at an angle different from that of the first inclined surface 25. If the first inclined surface 25 were not present and a vertical portion were formed at the boundary between the second plane 22E and the third surface 23, turbulence would occur, making it impossible to accurately measure wind speed. Therefore, by providing the third surface 23 with an inclination different from that of the first inclined surface 25, it is possible to ensure the calculated optimal first distance H while ensuring the necessary size for the second plane 22E and minimizing the size of the ultrasonic anemometer 100E. A portion of the third surface 23 is located directly below the ultrasonic transmitters / receivers 31-34. Furthermore, the ultrasonic anemometer 100D according to the fourth embodiment may also have a first inclined surface between the second flat surface 22D and the third surface 23.

[0088] [Ultrasonic Anemometer 100F According to Sixth Embodiment] Next, an ultrasonic anemometer 100F according to a sixth embodiment will be described. Fig. 11 is a schematic perspective view illustrating an ultrasonic anemometer 100 according to the sixth embodiment, and Fig. 12 is a plan view showing an example of the arrangement of the reflector 21 and the ultrasonic transceiver 30. The ultrasonic anemometer 100F shown in Fig. 11 differs from the ultrasonic anemometer 100 shown in Fig. 3 in that it includes a reflector 21F instead of the reflector 21, and in that the shape of the second plane 22B is different. Note that in the description of the 100F according to the sixth embodiment, descriptions similar to those of the ultrasonic anemometer 100 according to the above embodiments may be omitted.

[0089] [Second Plane 22F] The ultrasonic anemometer 100F includes a reflector 21F. The reflector 21F has a second plane 22F and a third plane 23. The second plane 22F may be the upper surface of the reflector 21F. The second plane 22F faces the first plane 12 in the Z-axis direction and is parallel to the first plane 12. The second plane 22F is a plane extending along the X-axis direction and the Y-axis direction. As shown in FIG. 12 , the second plane 22F is disposed at the center of the reflector 21F when viewed in the Z-axis direction. The reflector 21F has, for example, a substantially cross shape. Here, the portion extending outside the substantially cross shape in the Z-axis direction can be disposed between adjacent ultrasonic transmitter / receivers (e.g., ultrasonic transceiver 31 and ultrasonic transceiver 33). Furthermore, when viewed in the Z-axis direction, the second plane 22F includes an area overlapping with the first plane 12. The shape of the second plane 22F is not limited to a substantially cross shape, but may be a circle, a rectangle, or any other shape.

[0090] [Third surface 23] As shown in Fig. 2, the third surface 23 is inclined outward so as to face the opposite side from the second plane 22F (22). The third surface 23 includes a position overlapping with the ultrasonic transceiver 30 when viewed in the Z-axis direction. The third surface 23 includes a surface disposed in a position directly below the multiple ultrasonic transceivers 30. As shown in Fig. 6, the reflecting plate 21F (21) may have only the second plane 22 (22G) and may not have the third surface 23.

[0091] Next, transmission and reception of ultrasonic waves between the plurality of ultrasonic transmitters and receivers 31 to 34 will be described with reference to FIG.

[0092] [First ultrasonic wave (first ultrasonic transceiver 31 → second ultrasonic transceiver 32)] The ultrasonic wave transmitted from the first ultrasonic transceiver 31 and received by the second ultrasonic transceiver 32 is referred to as the "first ultrasonic wave 31x." The first ultrasonic wave 31x is reflected by the second plane 22 and received by the second ultrasonic transceiver 32. The first ultrasonic wave 31x received by the second ultrasonic transceiver 32 during wind speed measurement is referred to as the "first observation wave 31xr."

[0093] [Second ultrasonic wave (second ultrasonic transceiver 32 → first ultrasonic transceiver 31)] The ultrasonic wave transmitted from the second ultrasonic transceiver 32 and received by the first ultrasonic transceiver 31 is referred to as the "second ultrasonic wave 32x." The second ultrasonic wave 32x is reflected by the second plane 22 and received by the first ultrasonic transceiver 31. The second ultrasonic wave 32x received by the first ultrasonic transceiver 31 during wind speed measurement is referred to as the "second observation wave 32xr."

[0094] [First ultrasonic wave (third ultrasonic transceiver 33 → fourth ultrasonic transceiver 34)] The ultrasonic wave transmitted from the third ultrasonic transceiver 33 and received by the fourth ultrasonic transceiver 34 is referred to as the "first ultrasonic wave 33y." The first ultrasonic wave 33y is reflected by the second plane 22 and received by the fourth ultrasonic transceiver 34. When measuring wind speed, the first ultrasonic wave 33y received by the fourth ultrasonic transceiver 34 is referred to as the "first observation wave 33yr."

[0095] [Second ultrasonic wave (fourth ultrasonic transceiver 34 → third ultrasonic transceiver 33)] The ultrasonic wave transmitted from the fourth ultrasonic transceiver 34 and received by the third ultrasonic transceiver 33 is referred to as the "second ultrasonic wave 34y." The second ultrasonic wave 34y is reflected by the second plane 22 and received by the fourth ultrasonic transceiver 34. When measuring wind speed, the second ultrasonic wave 34y received by the fourth ultrasonic transceiver 34 is referred to as the "second observation wave 34yr."

[0096] [Third Ultrasonic Wave (First Ultrasonic Transmitter / Receiver 31 → Third Ultrasonic Transmitter / Receiver 33)] The ultrasonic wave transmitted from the first ultrasonic transceiver 31 and received by the third ultrasonic transceiver 33 is referred to as the "third ultrasonic wave 31d." The third ultrasonic wave 31d is reflected by the second plane 22 and received by the third ultrasonic transceiver 33. The third ultrasonic wave 31d received by the third ultrasonic transceiver 33 during wind speed measurement is referred to as the "third observation wave 31dr."

[0097] [Fourth ultrasonic wave (third ultrasonic transceiver 33 → first ultrasonic transceiver 31)] The ultrasonic wave transmitted from the third ultrasonic transceiver 33 and received by the first ultrasonic transceiver 31 is referred to as the "fourth ultrasonic wave 33d." The fourth ultrasonic wave 33d is reflected by the second plane 22 and received by the first ultrasonic transceiver 31. The fourth ultrasonic wave 33d received by the first ultrasonic transceiver 31 during wind speed measurement is referred to as the "fourth observation wave 33dr."

[0098] [Third ultrasonic wave (first ultrasonic transceiver 31 → fourth ultrasonic transceiver 34)] The ultrasonic wave transmitted from the first ultrasonic transceiver 31 and received by the fourth ultrasonic transceiver 34 is referred to as the "third ultrasonic wave 31c." The third ultrasonic wave 31c is reflected by the second plane 22 and received by the fourth ultrasonic transceiver 34. The third ultrasonic wave 31c received by the fourth ultrasonic transceiver 34 during wind speed measurement is referred to as the "third observation wave 31cr."

[0099] [Fourth ultrasonic wave (fourth ultrasonic transceiver 34 → first ultrasonic transceiver 31)] The ultrasonic wave transmitted from the fourth ultrasonic transceiver 34 and received by the first ultrasonic transceiver 31 is referred to as the "fourth ultrasonic wave 34c." The fourth ultrasonic wave 34c is reflected by the second plane 22 and received by the first ultrasonic transceiver 31. The fourth ultrasonic wave 34c received by the first ultrasonic transceiver 31 during wind speed measurement is referred to as the "fourth observation wave 34cr."

[0100] [Third Ultrasonic Wave (Second Ultrasonic Transmitter / Receiver 32 → Third Ultrasonic Transmitter / Receiver 33)] The ultrasonic wave transmitted from the second ultrasonic transceiver 32 and received by the third ultrasonic transceiver 33 is referred to as the "third ultrasonic wave 32a." The third ultrasonic wave 32a is reflected by the second plane 22 and received by the third ultrasonic transceiver 33. The third ultrasonic wave 32a received by the third ultrasonic transceiver 33 during wind speed measurement is referred to as the "third observation wave 32ar."

[0101] [Fourth ultrasonic wave (third ultrasonic transceiver 33 → second ultrasonic transceiver 32)] The ultrasonic wave transmitted from the third ultrasonic transceiver 33 and received by the second ultrasonic transceiver 32 is referred to as the "fourth ultrasonic wave 33a." The fourth ultrasonic wave 33a is reflected by the second plane 22 and received by the second ultrasonic transceiver 32. The fourth ultrasonic wave 33a received by the second ultrasonic transceiver 32 during wind speed measurement is referred to as the "third observation wave 33ar."

[0102] [Third Ultrasonic Wave (Second Ultrasonic Transceiver 32 → Fourth Ultrasonic Transceiver 34)] The ultrasonic wave transmitted from the second ultrasonic transceiver 32 and received by the fourth ultrasonic transceiver 34 is referred to as the "third ultrasonic wave 32b." The third ultrasonic wave 32b is reflected by the second plane 22 and received by the fourth ultrasonic transceiver 34. The third ultrasonic wave 32b received by the fourth ultrasonic transceiver 34 during wind speed measurement is referred to as the "third observation wave 32br."

[0103] [Fourth ultrasonic wave (fourth ultrasonic transceiver 34 → second ultrasonic transceiver 32)] The ultrasonic wave transmitted from the second ultrasonic transceiver 32 and received by the fourth ultrasonic transceiver 34 is referred to as the "fourth ultrasonic wave 34b." The fourth ultrasonic wave 34b is reflected by the second plane 22 and received by the fourth ultrasonic transceiver 34. The fourth ultrasonic wave 34b received by the fourth ultrasonic transceiver 34 during wind speed measurement is referred to as the "fourth observation wave 3bbr."

[0104] [Propagation Time] The propagation time T31x of the first observation wave 31xr and the propagation time T32x of the second observation wave 32xr are expressed by equations (9) and (10), respectively, using the reach distance A1, the sound speed C1, and the wind speed V.

[0105] T31x=A1 / (C1+V) (9) T32x=A1 / (C1-V) (10) Furthermore, from [Equation (9)-Equation (10)], Equation (11) regarding the wind speed V can be obtained.

[0106] V=(A1 / 2)[(1 / T31x)-(1 / T32x)] (11) [Measurement Unit 200] Next, the measurement unit 200 will be described. FIG. 13 is a block diagram illustrating an example of the hardware configuration of an ultrasonic anemometer 100F according to an embodiment. The ultrasonic anemometer 100F includes a measurement unit 200. The measurement unit 200 calculates the wind speed V in the flow path 101 based on data received from the ultrasonic transceiver 30. The measurement unit 200 can also calculate the wind direction. The measurement unit 200 may further have a function to display the calculation results of the wind speed V and the like. The measurement unit 200 may also output the calculation results of the wind speed V and the like to an external information processing device.

[0107] The measurement unit 200 includes a control circuit 210, a signal generation circuit 221, and a detection circuit 222. The ultrasonic anemometer 100 may include a temperature sensor 231. The measurement unit 200 is electrically connected to the multiple ultrasonic transceivers 30 and the temperature sensor 231. The measurement unit 200 may be a computer including the control circuit 210, the signal generation circuit 221, and the detection circuit 222. The measurement unit 200 may calculate the X-axis component Vx of the wind speed V using data acquired from the first ultrasonic transceiver 31 and the second ultrasonic transceiver 32. The measurement unit 200 may calculate the Y-axis component Vy of the wind speed V using data acquired from the third ultrasonic transceiver 33 and the fourth ultrasonic transceiver 34. This will be described in more detail below.

[0108] [Signal Generation Circuit 221] The signal generation circuit 221 generates an AC signal for causing the first ultrasonic transceiver 31 to oscillate the first observation wave 31xr, and outputs the first observation wave 31xr from the first ultrasonic transceiver 31. The signal generation circuit 221 also generates an AC signal for causing the second ultrasonic transceiver 32 to oscillate the second observation wave 32xr, and outputs the second observation wave 32xr from the second ultrasonic transceiver 32. An example of the AC signal generated by the signal generation circuit 221 is an analog electrical signal corresponding 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 ultrasonic transceiver 31 and the sine wave corresponding to the AC signal to the second ultrasonic transceiver 32 have approximately the same period (frequency).

[0109] An example of the signal generating circuit 221 is a circuit that includes an oscillator circuit including a quartz 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 the transceiver to which the AC signal is output in accordance with a selection signal input from the control circuit 210. However, the configuration of the signal generating circuit 221 is not limited to this.

[0110] [Detection circuit 222] The detection circuit 222 detects a signal related to the second observation wave 32xr received by the first ultrasonic transceiver 31. The signal related to the second observation wave 32xr may be referred to as a "second signal 32Sx." The detection circuit 222 also detects a signal related to the first observation wave 31xr received by the second ultrasonic transceiver 32. The signal related to the first observation wave 31xr may be referred to as a "first signal 31Sx."

[0111] The detection circuit 220 outputs the detected first signal 31Sx and second signal 32Sx to the control circuit 210.

[0112] An example of the detection circuit 220 is a circuit including a switching circuit that switches the output signal to the control circuit 210 between the first signal 31Sx and the second signal 32Sx, an amplifier circuit that amplifies the first signal 31Sx or the second signal 32Sx output through the switching circuit, and an analog-to-digital converter that converts an analog AC signal related to the amplified first signal 31Sx or the second signal 32Sx into a digital signal. However, the configuration of the detection circuit 220 is not limited to this.

[0113] [Temperature Sensor 231] The temperature sensor 231 may detect the temperature inside the flow path 101, for example, when measuring the wind speed. The temperature sensor 231 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 storage unit 212 of the control circuit 210. The information related to the temperature detected by the temperature sensor 231 can be used, for example, when calculating the sound speed C1.

[0114] The temperature sensor 231 may be any sensor capable of detecting the temperature inside the flow path 101. Examples of the temperature sensor 231 include a thermistor, a linear resistor, a platinum resistance thermometer, a thermocouple, and a thermopile.

[0115] [Control Circuit 210] The control circuit 210 includes, for example, a central processing unit (CPU) 211 and a storage unit 212. The storage unit 212 includes a read-only memory (ROM) 213 and a random access memory (RAM). The CPU 211 executes various processes according to, for example, programs stored in the storage unit 212. The programs, when executed by the CPU 211, can cause the measurement unit 200 to function as a means for measuring the wind speed V. The programs may be stored in an external storage medium, such as a hard disk or flash memory. Alternatively, the programs may be transmitted to the control circuit 210 via a communication line. The transmitted programs are installed in the storage unit 212 of the control circuit 210. The storage unit 212 stores various information necessary for calculating the wind speed V. The storage unit 211 stores information regarding the height H between the first plane 12 and the second plane 22, as well as information regarding the first distance D1 and the second distance D2 between the multiple ultrasonic transmitters / receivers 30. Furthermore, the control circuit 210 can output the calculated wind speed V to, for example, an external device.

[0116] The control circuit 210 calculates a first wind speed V1 using the results of diagonal ultrasonic wave transmission and reception by the first ultrasonic transceiver 31 to the fourth ultrasonic transceiver 34. The control circuit 210 calculates a second wind speed V2 using the results of adjacent ultrasonic wave transmission and reception by the first ultrasonic transceiver 31 to the fourth ultrasonic transceiver 34. The control circuit 210 outputs the second wind speed V2 when the difference between the first wind speed V1 and the second wind speed V2 satisfies a first condition. The control circuit 210 outputs the first wind speed V1 when the difference between the first wind speed V1 and the second wind speed V2 does not satisfy the first condition.

[0117] The first condition may be, for example, that the second wind speed Vd is equal to or greater than twice the first wind speed Vx. When the second wind speed Vd is equal to or greater than twice the first wind speed Vx, the control circuit 210 determines that the first condition is met and outputs the second wind speed V2 as the wind speed V. The first condition may be other conditions. The control circuit 210 may compare the first wind speed V1 with the second wind speed V2 to determine whether the first condition is met. The control circuit 210 may determine, for example, whether the first wind speed V1 is below a determination threshold to determine whether the first condition is met. The control circuit 210 may determine, for example, whether the second wind speed V2 exceeds the first determination threshold and the first wind speed V1 is below a second determination threshold that is lower than the first determination threshold to determine whether the first condition is met.

[0118] The first condition may be a determination threshold set depending on whether a "Tof shift" is likely to occur. For example, if a Tof shift is likely to occur at a wind speed of 45 m / s or more, a wind speed of 45 m / s or more may be set as the first condition. Here, a "Tof shift" may be defined as a case where the difference (phase difference) between the propagation time of an ultrasonic wave on the outbound path and the propagation time of an ultrasonic wave on the return path exceeds one period. In other words, "the occurrence of a Tof shift" may be expressed as "the phase rotates one period."

[0119] The control circuit 210 calculates the first wind speed Vy using the results of ultrasonic transmission and reception between the third ultrasonic transceiver 33 and the fourth ultrasonic transceiver 34. The control circuit 210 calculates the second wind speed Vy using the results of ultrasonic transmission and reception between the third ultrasonic transceiver 33 and the second ultrasonic transceiver 32, and between the second ultrasonic transceiver 32 and the fourth ultrasonic transceiver 34. ２ The control circuit 210 calculates the first wind speed Vy and the second wind speed Vy ２ If the difference between the first wind speed Vy and the second wind speed Vy does not satisfy the first condition, the control circuit 210 calculates the wind speed V using the first wind speed Vy. ２ When the difference satisfies the first condition, the second wind speed Vy ２ The wind speed is calculated using the formula: In other words, the first condition can be determined based on the vector component that is the basis for calculating the wind speed V. Also, although the Y-axis component has been used as an example in the description here, the first condition can also be determined based on the X-axis component.

[0120] The control circuit 210 can calculate the second wind speed Vc using the results of transmission and reception of ultrasonic waves between the first ultrasonic transceiver 31 and the fourth ultrasonic transceiver 34 .

[0121] The control circuit 210 can calculate the second wind speed Va using the results of transmission and reception of ultrasonic waves between the second ultrasonic transceiver 32 and the third ultrasonic transceiver 33 .

[0122] The control circuit 210 can calculate the second wind speed Vb using the results of transmission and reception of ultrasonic waves between the second ultrasonic transceiver 32 and the fourth ultrasonic transceiver 34 .

[0123] When determining whether the first condition is satisfied, the control circuit 210 may use at least one of the second wind velocities Va to Vd to determine whether the first condition is satisfied.

[0124] Figure 14(a) is a graph illustrating the waveforms of signals corresponding to the first and second observation waves, and Figure 14(b) is a graph illustrating the waveforms of signals corresponding to the third and fourth observation waves.

[0125] The horizontal axis in Fig. 14(a) represents the elapsed time from the start of transmission of the first observation wave 31xr or the second observation wave 32xr. The origin of the horizontal axis in the figure corresponds to a predetermined time after the start of transmission of the first observation wave 31xr or the second observation wave 32xr. The vertical axis in Fig. 14(a) represents the amplitude of the first signal 31Sx corresponding to the first observation wave 31xr and the second signal 32Sx corresponding to the second observation wave 32xr.

[0126] The horizontal axis in Fig. 14(b) represents the elapsed time from the start of transmission of the third observation wave 31dr or the fourth observation wave 33dr. The origin of the horizontal axis in the figure corresponds to a point in time a predetermined time has elapsed since the start of transmission of the third observation wave 31dr or the fourth observation wave 33dr. The vertical axis in Fig. 14(b) represents the amplitude of the third signal 31Sd corresponding to the third observation wave 31dr and the fourth signal 33Sd corresponding to the second observation wave 32xr.

[0127] The control circuit 210 calculates the first wind speed Vx using the first time t31xa when the first ultrasonic wave 31x is transmitted from the first ultrasonic transceiver 31 and the first ultrasonic wave 31x is received by the second ultrasonic transceiver 32, and the second time t32xa when the second ultrasonic wave 32x is transmitted from the second ultrasonic transceiver 32 and the second ultrasonic wave 32x is received by the first ultrasonic transceiver 31.

[0128] The control circuit 210 can calculate the second wind speed Vd using the third time t31da when the third ultrasonic wave 31d is transmitted from the first ultrasonic transceiver 31 and received by the third ultrasonic transceiver 33, and the fourth time t33da when the fourth ultrasonic wave 33d is transmitted from the third ultrasonic transceiver 33 and received by the first ultrasonic transceiver 31.

[0129] The control circuit 210 calculates the first wind speed Vy using the first time t33ya when the first ultrasonic wave 33y is transmitted from the third ultrasonic transceiver 33 and received by the fourth ultrasonic transceiver 34, and the second time t34ya when the second ultrasonic wave 34y is transmitted from the fourth ultrasonic transceiver 34 and received by the third ultrasonic transceiver 33.

[0130] The control circuit 210 calculates the second wind speed Vc using the third time t31ca when the third ultrasonic wave 31c is transmitted from the first ultrasonic transceiver 31 and received by the fourth ultrasonic transceiver 34, and the fourth time t34ca when the fourth ultrasonic wave 33c is transmitted from the fourth ultrasonic transceiver 34 and received by the first ultrasonic transceiver 31.

[0131] The control circuit 210 can calculate the second wind speed Va using the third time t32aa when the third ultrasonic wave 32a is transmitted from the second ultrasonic transceiver 32 and received by the third ultrasonic transceiver 33, and the fourth time t33aa when the fourth ultrasonic wave 33a is transmitted from the third ultrasonic transceiver 33 and received by the second ultrasonic transceiver 32.

[0132] The control circuit 210 can calculate the second wind speed Vb using the third time t32ba when the third ultrasonic wave 32b is transmitted from the second ultrasonic transceiver 32 and received by the fourth ultrasonic transceiver 34, and the fourth time t34ba when the fourth ultrasonic wave 34b is transmitted from the fourth ultrasonic transceiver 34 and received by the second ultrasonic transceiver 32.

[0133] The control circuit 210 determines as the first time t31xa the time closest to the fifth time t5 among the times at which the amplitude is 0 when the second ultrasonic transceiver 32 receives the first ultrasonic wave 31x. The control circuit 210 determines as the second time t32xa the time closest to the fifth time t5 among the times at which the amplitude is 0 when the first ultrasonic transceiver 31 receives the second ultrasonic wave 32x. The control circuit 210 calculates the first wind speed Vx using the first time t31xa and the second time t32xa.

[0134] The control circuit 210 determines the time closest to the fifth time t5 among the times when the amplitude is 0 when the third ultrasonic wave 31d is received by the third ultrasonic transceiver 33 as the third time t31da.The control circuit 210 determines the time closest to the fifth time t5 among the times when the amplitude is 0 when the first ultrasonic wave 33d is received by the first ultrasonic transceiver 31 as the fourth time t33da, and calculates the second wind speed Vd.

[0135] The control circuit 210 determines the time closest to the fifth time t5 among the times when the amplitude is 0 when the fourth ultrasonic transceiver 34 receives the first ultrasonic wave 33y as the first time t33ya. The control circuit 210 determines the time closest to the fifth time t5 among the times when the amplitude is 0 when the third ultrasonic transceiver 33 receives the second ultrasonic wave 34y as the second time t34ya. The control circuit 210 calculates the first wind speed Vy using the first time t33ya and the second time t34ya.

[0136] The control circuit 210 determines the time closest to the fifth time t5 among the times at which the amplitude of the third ultrasonic wave 31c is 0 when the fourth ultrasonic transceiver 34 receives it as the third time t31ca.The control circuit 210 determines the time closest to the fifth time t5 among the times at which the amplitude of the fourth ultrasonic wave 34c is 0 when the first ultrasonic transceiver 31 receives it as the fourth time t34ca, and calculates the second wind speed Vc.

[0137] The control circuit 210 determines the time closest to the fifth time t5 among the times when the amplitude is 0 when the third ultrasonic wave 32a is received by the third ultrasonic transceiver 33 as the third time t32aa.The control circuit 210 determines the time closest to the fifth time t5 among the times when the amplitude is 0 when the second ultrasonic wave 33a is received by the second ultrasonic transceiver 32 as the fourth time t33aa, and calculates the second wind speed Va.

[0138] The control circuit 210 determines the time closest to the fifth time t5 among the times at which the amplitude is 0 when the fourth ultrasonic wave 32b is received by the fourth ultrasonic wave transceiver 34 as the third time t32ba.The control circuit 210 determines the time closest to the fifth time t5 among the times at which the amplitude is 0 when the second ultrasonic wave 34b is received by the second ultrasonic wave transceiver 32 as the fourth time t34ba, and calculates the second wind speed Vb.

[0139] [Measuring Principle of Wind Speed ​​V] Next, an example of the measuring principle of wind speed V will be described. An example of the measuring principle of wind speed V will be described with reference to FIG. 15 . FIG. 15 is a graph illustrating waveforms of signals corresponding to the first observation wave and the second observation wave. The horizontal axis of FIG. 15 indicates the elapsed time from the start of transmission of the first observation wave 31xr or the second observation wave 32xr. The origin of the horizontal axis of the graph corresponds to a predetermined time after the start of transmission of the first observation wave 31xr or the second observation wave 32xr. The vertical axis of FIG. 15 indicates the amplitude of the first signal 31Sx corresponding to the first observation wave 31xr and the second signal 32Sx corresponding to the second observation wave 32xr. FIG. 15(a) shows the waveforms of the first signal 31Sx and the second signal 32Sx when the wind speed V in the flow path 101 is Vxa [m / s]. Note that Vxa is a non-zero value. FIG. 15B shows the waveform of the first signal 31Sx and the waveform of the second signal 32Sx when the wind speed V in the flow path 101 is Vxb [m / s] which is greater than Vxa.

[0140] In the comparative example, for the propagation time T31x, for example, a time point at which the peak value of the first signal 31Sx becomes zero (time point t31xa in FIG. 15A) is detected, and for the propagation time T32x, for example, a time point at which the peak value of the second signal 32Sx becomes zero (time point t32xa in FIG. 15A) is detected. The time point t31xa is set to be a time point belonging to the n-th period of the first signal 31Sx. The time point t32xa is set to be a time point belonging to the n-th period of the second signal 32Sx. In other words, the time points t31xa and t32xa are time points specified by the same peak value that belong to the same numbered periods of the signals related to the first signal 31Sx and the second signal 32Sx. Note that the propagation time T １ Regarding the propagation time T32x, a time point at which the peak value of the first signal 31Sx is a value other than zero may be detected. Regarding the propagation time T32x, a time point at which the peak value of the second signal 32Sx is a value other than zero may be detected.

[0141] 15A, if the difference between the phase of the first signal 31Sx corresponding to time t31xa and the phase of the second signal 32Sx corresponding to time t32xa is equal to or less than one period of the first signal 31Sx or the second signal 32Sx (e.g., 2π), the points in time at which the first signal 31Sx and the second signal 32Sx have the same peak value and belong to the same numbered periods are close in time series, and therefore the points in time at which the first signal 31Sx and the second signal 32Sx have the same peak value and belong to the same numbered periods can be properly detected.

[0142] On the other hand, as shown in FIG. 15B, when the wind speed V increases, the difference between the phase corresponding to time t31xa of the first signal 31Sx and the phase corresponding to time t32xa of the second signal 32Sx exceeds the value of one cycle of the first signal 31Sx or the second signal 32Sx. In this case, the points in time at which the first signal 31Sx and the second signal 32Sx have the same peak value but which belong to the same numbered cycle are chronologically distant from each other. Therefore, for example, in the second signal 32Sx, there is a possibility that a point t32xb in the (n-1)th cycle, which is close to time t31xa of the first signal 31Sx, may be detected. The same applies to the first signal 31Sx. That is, there is a possibility that points in time at which the first signal 31Sx and the second signal 32Sx have the same peak value but which belong to different numbered cycles from each other may be detected, resulting in an erroneous measurement of the wind speed V.

[0143] Here, if the starting points of the first signal 31Sx and the second signal 32Sx were aligned, the nth period could be correctly determined. However, because vibrations generated when the ultrasonic transceiver transmits ultrasonic waves are transmitted through the first housing 10 to the other ultrasonic transceiver, the starting point of the first signal 31Sx cannot be determined. This phenomenon is called housing propagation. Similarly, the starting point of the second signal 32Sx cannot be determined due to housing propagation. This phenomenon occurs more significantly when the distance between the ultrasonic transceivers is shortened due to miniaturization. Therefore, the nth period of the first signal 31Sx is determined to be the point at which a predetermined time has elapsed since the transceiver started transmitting ultrasonic waves, and the period of the second signal 32Sy that is close to time t31xa is determined to belong to the nth period.

[0144] [Procedures of Wind Speed ​​Measurement Method] Next, procedures of the wind speed measurement method according to the sixth embodiment will be described with reference to FIG. 16 . FIG. 16 is a flowchart illustrating procedures of the wind speed measurement method according to the sixth embodiment. In the wind speed measurement method, first, a first wind speed Vx and a first wind speed Vy are calculated (step S11). In step S11, as described above, the measurement unit 200 calculates the first wind speed Vx using data acquired from the first ultrasonic transceiver 31 and the second ultrasonic transceiver 32 that face each other in the X-axis direction. Also, in step S11, the measurement unit 200 calculates the first wind speed Vy using data acquired from the third ultrasonic transceiver 33 and the fourth ultrasonic transceiver 34 that face each other in the Y-axis direction.

[0145] In step S11, the measurement unit 200 may use the first wind speed Vx and the first wind speed Vy to calculate the wind speed V. The measurement unit 200 can calculate the first wind speed V1 by using the first wind speed Vx as the X-axis component of the wind speed V and the first wind speed Vy as the Y-axis component of the wind speed V.

[0146] Next, in the wind speed measurement method, second wind speeds Va, Vb, Vc, and Vd are calculated (step S12). In step S12, the measurement unit 200 calculates the second wind speed Vd using data acquired from the first ultrasonic transceiver 31 and the third ultrasonic transceiver 33, as described above. Also in step S12, the measurement unit 200 calculates the second wind speed Vc using data acquired from the first ultrasonic transceiver 31 and the fourth ultrasonic transceiver 34. Also in step S12, the measurement unit 200 calculates the second wind speed Va using data acquired from the second ultrasonic transceiver 32 and the third ultrasonic transceiver 33. Also in step S12, the measurement unit 200 calculates the second wind speed Vb using data acquired from the second ultrasonic transceiver 32 and the fourth ultrasonic transceiver 34.

[0147] In step S12, the measurement unit 200 can calculate the second wind speed V2 using the second wind speed Va, the second wind speed Vb, the second wind speed Vc, and the second wind speed Vd.

[0148] Next, in the wind speed measurement method, the measurement unit 200 determines whether a first condition is met (step S13). If the first condition is met (step S13; YES), the measurement unit 200 executes the process of step S14. If the first condition is not met (step S13; NO), the measurement unit 200 executes the process of step S15.

[0149] The measurement unit 200 may determine that the first condition is met when the difference between the first wind speed V1 and the second wind speed V2 satisfies the first condition. The measurement unit 200 may determine whether the first condition is met by determining whether the second wind speed V2 is at least twice the first wind speed V1. The measurement unit 200 may, for example, compare the first wind speed V1 with the second wind speed V2 to determine whether the first condition is met. The measurement unit 200 may, for example, determine that the first condition is met when the second wind speed V2 is greater than the first wind speed V1.

[0150] The measurement unit 200 may compare the first wind speed V1 calculated using the first wind speed Vx and the first wind speed Vy with the second wind speed V2 calculated using the second wind speeds Va to Vd to determine whether the first condition is met. ２ The measurement unit 200 may determine whether the first condition is met by determining whether the difference between the first wind speed Vy and the second wind speeds Va to Vd satisfies the first condition. ２ The measurement unit 200 may determine whether the first condition is met by determining whether the difference between the second wind velocities Va and Vd satisfies the first condition. ２ and wind speed Vy ２ is equal to or greater than twice the wind speed V calculated using the first wind speed Vx and the first wind speed Vy, to determine whether the first condition is met.

[0151] The measurement unit 200 may determine whether the first condition is met by comparing at least one of the first wind speed Vx and the first wind speed Vy with at least one of the second wind speeds Va to Vd.

[0152] Furthermore, the diagonal transmission and reception paths UTx and UTy are longer than the adjacent transmission and reception paths UTa, UTb, UTc, and UTd. This means that the diagonal transmission and reception paths UTx and UTy have a longer time during which the ultrasonic waves are exposed to the wind than the adjacent transmission and reception paths UTa, UTb, UTc, and UTd. Therefore, the accuracy of the wind speed is higher for the diagonal transmission and reception paths UTx and UTy than for the adjacent transmission and reception paths UTa, UTb, UTc, and UTd. On the other hand, because the diagonal transmission and reception paths UTx and UTy have a longer time during which they are exposed to the wind, they are more likely to experience a Tof shift than the adjacent transmission and reception paths UTa, UTb, UTc, and UTd.

[0153] The first condition assumes that a Tof shift occurs in the diagonal transmission / reception paths UTx and UTy, but no Tof shift occurs in the adjacent transmission / reception paths UTa, UTb, UTc, and UTd. Here, when the wind speed increases, a Tof shift occurs in the diagonal transmission / reception paths UTx and UTy, causing the wind speed calculated from the diagonal transmission / reception paths UTx and UTy to be calculated as extremely small. In other words, the wind speed calculated in the diagonal transmission / reception paths UTx and UTy differs by more than two times from the wind speed calculated in the adjacent transmission / reception paths UTa, UTb, UTc, and UTd. Here, since no Tof shift occurs in the adjacent transmission / reception paths UTa, UTb, UTc, and UTd, the wind speed is calculated correctly. This deviation is used as the first condition. If the first condition is met, the correct second wind speed is output. If the first condition is not met, the first wind speed, which has a higher wind speed accuracy, is output.

[0154] If the first condition is not met (step S13; NO), the measurement unit 200 outputs the first wind speeds Vx and Vy (step S14). The measurement unit 200 may output the wind speed V calculated using the first wind speed Vx and the first wind speed Vy. Note that "output" may mean displaying on a display unit, outputting audio by an audio output unit, or outputting to a processing device connected to the ultrasonic anemometer 100.

[0155] If the first condition is met (step S13; YES), the measurement unit 200 outputs the second wind speeds Va to Vd (step S15). The measurement unit 200 may output the wind speed V calculated using the second wind speeds Va to Vd.

[0156] [Operation and effect of ultrasonic anemometer 100F according to sixth embodiment] The ultrasonic anemometer 100F according to the sixth embodiment includes a first ultrasonic transceiver 31, a second ultrasonic transceiver 32 that is separated from the first ultrasonic transceiver 31 by a third distance D3 in the X-axis direction (first direction), and a third ultrasonic transceiver 33 that is separated from the first ultrasonic transceiver 31 by a fourth distance D4 that is shorter than the third distance D3 in a direction different from the X-axis direction, and displays the results of ultrasonic transmission and reception between the first ultrasonic transceiver 31 and the second ultrasonic transceiver 32 and the results of ultrasonic transmission and reception between the first ultrasonic transceiver 31 and the third ultrasonic transceiver 33. The control circuit 210 calculates a first wind speed Vx using the results of ultrasonic transmission and reception between the first ultrasonic transceiver 31 and the second ultrasonic transceiver 32, calculates a second wind speed Vd using the results of ultrasonic transmission and reception between the first ultrasonic transceiver 31 and the third ultrasonic transceiver 33, and outputs the first wind speed Vx if the difference between the first wind speed Vx and the second wind speed Vd satisfies a first condition, and outputs the second wind speed Vd if the difference between the first wind speed Vx and the second wind speed Vd does not satisfy the first condition. Note that the first wind speed may be the first wind speed Vy, and the second wind speed may be the second wind speeds Va, Vb, or Vc.

[0157] In this ultrasonic anemometer 100F, whether to output the first wind speed Vx or the second wind speed Vd can be changed depending on whether the first condition is met. This improves the measurement accuracy of the ultrasonic anemometer 100. By changing the wind speed to be output depending on whether the first condition is met, it is possible to adopt the first wind speed Vx or the second wind speed Vd, whichever is more accurate.

[0158] In addition, the ultrasonic anemometer 100F may further include a fourth ultrasonic transceiver 34 that faces the third ultrasonic transceiver 33 in the Y-axis direction (second direction) that intersects the X-axis direction and is a fourth distance D4 away from the first ultrasonic transceiver 31.

[0159] The control circuit 210 may calculate first wind speeds Vx, Vy using the results of ultrasonic transmission and reception between the first ultrasonic transceiver 31 and the second ultrasonic transceiver 32 and the results of ultrasonic transmission and reception between the third ultrasonic transceiver 33 and the fourth ultrasonic transceiver 34, and may calculate second wind speeds Va, Vb, Vc using the results of ultrasonic transmission and reception between the first ultrasonic transceiver 31 and the third ultrasonic transceiver 33, the results of ultrasonic transmission and reception between the first ultrasonic transceiver 31 and the fourth ultrasonic transceiver 34, the results of ultrasonic transmission and reception between the second ultrasonic transceiver 32 and the third ultrasonic transceiver 333, and the results of ultrasonic transmission and reception between the second ultrasonic transceiver 32 and the fourth ultrasonic transceiver 34.

[0160] The ultrasonic anemometer 100F further includes a top plate 11 on which a first ultrasonic transceiver 31, a second ultrasonic transceiver 32, a third ultrasonic transceiver 33, and a fourth ultrasonic transceiver 34 are mounted, a reflecting plate (bottom plate) 21 facing the top plate 11 in the Z-axis direction (third direction), and a plurality of support columns 13 extending from the reflecting plate 21 in the Z-axis direction and supporting the top plate 11. When viewed in the Z-axis direction, the plurality of support columns 13 are arranged at positions that do not overlap with an imaginary first line connecting the first ultrasonic transceiver 31 and the second ultrasonic transceiver 32, and an imaginary second line connecting the third ultrasonic transceiver 33 and the fourth ultrasonic transceiver 34.

[0161] In the ultrasonic anemometer 100F having this configuration, the multiple support pillars 13 are not arranged on the ultrasonic transmission / reception path between the first ultrasonic transceiver 31 and the second ultrasonic transceiver 32. Similarly, the multiple support pillars 13 are not arranged on the ultrasonic transmission / reception path between the third ultrasonic transceiver 33 and the fourth ultrasonic transceiver 34. In the ultrasonic anemometer 100F, it is possible to prevent the multiple support pillars 13 from being arranged on the ultrasonic transmission / reception path between the multiple ultrasonic transceivers 30. As a result, the ultrasonic anemometer 100F can accurately measure wind direction and wind speed by arranging the support pillars 13 so as not to affect the flow of the fluid to be measured.

[0162] In the ultrasonic anemometer 100F, ultrasonic transmission and reception paths can be formed on the X-axis and Y-axis, and the X-axis component Vx and Y-axis component Vy of the wind speed V can be directly extracted, allowing for accurate calculation of the wind speed V. Furthermore, in the ultrasonic anemometer 100F, the distance between the first ultrasonic transceiver 31 and the second ultrasonic transceiver 32 and the distance between the third ultrasonic transceiver 33 and the fourth ultrasonic transceiver 34 can be long, thereby improving measurement accuracy.

[0163] Furthermore, the ultrasonic anemometer 100F can change the output wind speed depending on whether the first condition is met. The ultrasonic anemometer 100F can select and output an appropriate wind speed V from among the wind speed V based on the first wind speed Vx and the first wind speed Vy and the wind speed V based on the second wind speeds Va to Vd, thereby avoiding a windless determination in a strong wind across phases. The ultrasonic anemometer 100F avoids adopting data that differs from the actual phase difference due to a phase shift of one cycle or more. Therefore, the ultrasonic anemometer 100F is prevented from calculating a wind speed significantly lower than the actual wind speed.

[0164] The ultrasonic anemometer 100F can output the wind speed V based on the second wind velocities Va to Vd when there is a large difference between the wind speed V based on the first wind speeds Vx and Vy and the wind speed V based on the second wind velocities Va to Vd. This allows the ultrasonic anemometer 100F to expand the range over which the wind speed V can be measured with high accuracy. The ultrasonic anemometer 100F can expand the range over which the wind speed V can be measured with high accuracy even in strong winds.

[0165] It should be noted that the present invention is not limited to the configurations shown here, and other embodiments may be possible in which other components are combined with the configurations described in the above embodiments. In this regard, the present invention can be modified within the scope of the present invention, and can be appropriately determined depending on the application form.

[0166] In the above embodiment, an example is given of the ultrasonic anemometer 100 including a first ultrasonic transceiver 31, a second ultrasonic transceiver 32, a third ultrasonic transceiver 33, and a fourth ultrasonic transceiver 34, but the ultrasonic anemometer 100 may also include three or more ultrasonic transceivers 30.

[0167] Furthermore, in the above embodiment, an example is given in which the ultrasonic transceivers 30 are arranged at each corner of a square, but the arrangement of the ultrasonic transceivers 30 is not limited to this. The ultrasonic transceivers 30 may be arranged at the corners of a rhombus, a parallelogram, a trapezoid, or any other polygon.

[0168] In the above embodiment, the X-axis direction is the first direction and the Y-axis direction is the second direction, but the first and second directions are not limited to this. The Y-axis direction may be the first direction and the X-axis direction may be the second direction. The first and second directions may be other directions. Similarly, the direction in which the multiple ultrasonic transmitter / receivers 30 are adjacent to each other is not limited to the above-mentioned direction.

[0169] [Background Art] For example, an ultrasonic anemometer is known in which a plurality of transducers each equipped with a piezoelectric vibrator are arranged so that they can transmit and receive ultrasonic signals to and from each other. In this ultrasonic anemometer, an ultrasonic signal is transmitted from one of the transducers and received by the remaining transducers, and this operation is repeated by sequentially switching the transducer that transmits the ultrasonic signal, thereby measuring the propagation time of the ultrasonic signal in both directions between the transducers for all combinations of transducer pairs (e.g., JP 2009-229256 A).

[0170] This ultrasonic anemometer calculates n·(n−1) / 2 wind direction and speed vectors for n transducers from the measured ultrasonic signal propagation time. Of the calculated wind direction and speed vectors, this ultrasonic anemometer excludes wind direction and speed values ​​that differ by more than a predetermined threshold.

[0171] [Problem] However, the ultrasonic anemometer according to the prior art does not address the problem of erroneous determination of wind direction and speed in strong winds.

[0172] An object of the present disclosure is to provide an ultrasonic anemometer and a wind speed measurement method that can improve measurement accuracy.

[0173] This international application claims priority based on Japanese Patent Application No. 2024-055913 filed on March 29, 2024, Japanese Patent Application No. 2024-055915 filed on March 29, 2024, and Japanese Patent Application No. 2024-191128 filed on October 30, 2024, and the entire contents of Japanese Patent Application No. 2024-055913, Japanese Patent Application No. 2024-055915, and Japanese Patent Application No. 2024-191128 are incorporated by reference into this international application.

[0174] 100, 100B, 100C, 100D, 100E, 100F: ultrasonic anemometer, 11: top plate, 12: first plane, 21, 21B, 21C, 21D, 21E, 21F: reflecting plate, 22, 22B, 22C, 22D, 22E, 22F: second plane, 23: third surface (second inclined surface), 24a: area (first area), 24b to 24e: second area, 25: first inclined surface, 30: multiple ultrasonic transceivers, 31: ultrasonic transceiver (first ultrasonic transceiver), 32: ultrasonic transceiver (second ultrasonic transceiver), 33: ultrasonic transceiver (third ultrasonic transceiver), 34: ultrasonic transceiver (fourth ultrasonic transceiver), X: X-axis direction (first direction), Y: Y-axis direction (second direction), Z: Z-axis direction (third direction).

Claims

1. An ultrasonic anemometer comprising: a top plate having a first plane that is aligned with a first direction and a second direction that intersects with the first direction; a first ultrasonic transceiver and a second ultrasonic transceiver mounted on the top plate and positioned a predetermined distance from the first plane in the first direction; and a reflector positioned opposite the first plane in a third direction that intersects with the first and second directions, the reflector having a second plane that is parallel to the first plane and that is a first distance from the first plane, the reflector including a position that overlaps with the first ultrasonic transceiver in the third direction, and the third surface that is a second distance from the first ultrasonic transceiver in the third direction that is longer than the first distance.

2. The ultrasonic anemometer according to claim 1, wherein the third surface is disposed opposite the first ultrasonic transmitter / receiver and the second ultrasonic transmitter / receiver in the third direction and includes an inclined surface inclined relative to the second plane, the inclined surface inclined so as to face the opposite side to the second plane.

3. An ultrasonic anemometer as described in claim 1 or 2, further comprising a third ultrasonic transceiver and a fourth ultrasonic transceiver mounted on the top plate and arranged on both sides of the first plane in the second direction, wherein the first ultrasonic transceiver, the second ultrasonic transceiver, the third ultrasonic transceiver, and the third ultrasonic transceiver are arranged at positions corresponding to the vertices of a square when viewed in the third direction, and the second plane forms a circle when viewed in the third direction.

4. The ultrasonic anemometer according to any one of claims 1 to 3, further comprising a third ultrasonic transceiver and a fourth ultrasonic transceiver mounted on the top plate and arranged on both sides of the first plane in the second direction, wherein the first ultrasonic transceiver, the second ultrasonic transceiver, the third ultrasonic transceiver, and the third ultrasonic transceiver are arranged at positions corresponding to the vertices of a square when viewed in the third direction, and the second plane forms a cross shape when viewed in the third direction.

5. The ultrasonic anemometer according to any one of claims 1 to 3, further comprising a third ultrasonic transceiver and a fourth ultrasonic transceiver mounted on the top plate and arranged on both sides of the first plane in the second direction, wherein the first ultrasonic transceiver, the second ultrasonic transceiver, the third ultrasonic transceiver, and the third ultrasonic transceiver are arranged at positions corresponding to vertices of a square when viewed in the third direction, and the second plane forms a cross shape when viewed in the third direction, and the tip of the cross shape forms an arc shape.

6. An ultrasonic anemometer according to claim 4 or 5, wherein the cross-shaped second plane includes a rectangular first area located in the center and a plurality of second areas extending out from each side of the first area, and at least a portion of the second area is located directly below the first ultrasonic transceiver, the second ultrasonic transceiver, the third ultrasonic transceiver, and the fourth ultrasonic transceiver in the third direction.

7. When the first distance is H1, the third distance between the first ultrasonic transceiver and the second ultrasonic transceiver is D3, the wavelength of one period of the ultrasonic waves transmitted from the first ultrasonic transceiver and the second ultrasonic transceiver is L, and n is a natural number, the following formulas (1) and (2) are satisfied: The ultrasonic anemometer according to any one of claims 1 to 6.

8. The apparatus further comprises a third ultrasonic transceiver and a fourth ultrasonic transceiver mounted on the top plate and disposed on both sides of the first plane in the second direction, and when a fourth distance between the first ultrasonic transceiver and the third ultrasonic transceiver is D4, the apparatus satisfies the following formulas (3) and (4):

8. The ultrasonic anemometer according to claim 7.

9. An ultrasonic anemometer according to any one of claims 1 to 8, wherein at least a portion of the second plane is disposed directly below the first ultrasonic transmitter / receiver and the second ultrasonic transmitter / receiver in the third direction.

10. The ultrasonic anemometer according to claim 9, wherein the reflector has a first inclined surface formed around the second plane and inclined relative to the second plane, the third surface is formed outside the first inclined surface and includes a second inclined surface inclined relative to the second plane at an angle different from that of the first inclined surface, the first inclined surface and the second inclined surface are inclined so as to face away from the second plane, and the first inclined surface is treated with an anti-reflection coating to suppress reflection of ultrasonic waves.

11. The ultrasonic anemometer according to claim 1, further comprising a third ultrasonic transceiver mounted on the top plate and arranged on both sides of the first plane in the second direction, and a control circuit that performs arithmetic processing using the results of ultrasonic transmission and reception between the first ultrasonic transceiver and the second ultrasonic transceiver and the results of ultrasonic transmission and reception between the first ultrasonic transceiver and the third ultrasonic transceiver, wherein the control circuit: calculates a first wind speed using the results of ultrasonic transmission and reception between the first ultrasonic transceiver and the second ultrasonic transceiver; calculates a second wind speed using the results of ultrasonic transmission and reception between the first ultrasonic transceiver and the third ultrasonic transceiver; outputs the first wind speed when the difference between the first wind speed and the second wind speed does not satisfy a first condition; and outputs the second wind speed when the difference between the first wind speed and the second wind speed satisfies a first condition.

12. An ultrasonic anemometer comprising: a first ultrasonic transceiver; a second ultrasonic transceiver located a third distance in a first direction from the first ultrasonic transceiver; a third ultrasonic transceiver located a fourth distance from the first ultrasonic transceiver in a direction different from the first direction that is shorter than the third distance; and a control circuit that performs arithmetic processing using results of ultrasonic transmission and reception between the first ultrasonic transceiver and the second ultrasonic transceiver and results of ultrasonic transmission and reception between the first ultrasonic transceiver and the third ultrasonic transceiver, wherein the control circuit: calculates a first wind speed using results of ultrasonic transmission and reception between the first ultrasonic transceiver and the second ultrasonic transceiver; calculates a second wind speed using results of ultrasonic transmission and reception between the first ultrasonic transceiver and the third ultrasonic transceiver; outputs the first wind speed when a difference between the first wind speed and the second wind speed does not satisfy a first condition; and outputs the second wind speed when a difference between the first wind speed and the second wind speed satisfies a first condition.

13. The ultrasonic anemometer according to claim 12, wherein the first condition is that the second wind speed is at least twice the first wind speed.

14. The ultrasonic anemometer according to claim 12 or 13, wherein the control circuit calculates the first wind speed using a first time when a first ultrasonic wave is transmitted from the first ultrasonic transceiver and the second ultrasonic transceiver receives the first ultrasonic wave, and a second time when a second ultrasonic wave is transmitted from the second ultrasonic transceiver and the first ultrasonic transceiver receives the second ultrasonic wave, and calculates the second wind speed using a third time when a third ultrasonic wave is transmitted from the first ultrasonic transceiver and the third ultrasonic transceiver receives the third ultrasonic wave, and a fourth time when a fourth ultrasonic wave is transmitted from the third ultrasonic transceiver and the first ultrasonic transceiver receives the fourth ultrasonic wave.

15. The ultrasonic anemometer according to claim 14, wherein the control circuit calculates the first wind speed by setting the first time as the time closest to the fifth time among the times when the amplitude is 0 when the second ultrasonic transmitter / receiver receives the first ultrasonic wave, and the second time as the time closest to the fifth time among the times when the amplitude is 0 when the first ultrasonic transmitter / receiver receives the second ultrasonic wave, and the third time as the time closest to the fifth time among the times when the amplitude is 0 when the third ultrasonic transmitter / receiver receives the third ultrasonic wave, and the fourth time as the time closest to the fifth time among the times when the amplitude is 0 when the first ultrasonic transmitter / receiver receives the fourth ultrasonic wave.

16. The ultrasonic anemometer according to any one of claims 12 to 15, further comprising a fourth ultrasonic transceiver facing the third ultrasonic transceiver in a second direction intersecting the first direction and separated by the fourth distance from the first ultrasonic transceiver, wherein the control circuit calculates the first wind speed using the results of ultrasonic transmission and reception between the first ultrasonic transceiver and the second ultrasonic transceiver and the results of ultrasonic transmission and reception between the third ultrasonic transceiver and the fourth ultrasonic transceiver, and calculates the second wind speed using the results of ultrasonic transmission and reception between the first ultrasonic transceiver and the third ultrasonic transceiver, the results of ultrasonic transmission and reception between the first ultrasonic transceiver and the fourth ultrasonic transceiver, the results of ultrasonic transmission and reception between the second ultrasonic transceiver and the third ultrasonic transceiver, and the results of ultrasonic transmission and reception between the second ultrasonic transceiver and the fourth ultrasonic transceiver.

17. The ultrasonic anemometer of claim 16, further comprising: a top plate on which the first ultrasonic transceiver, the second ultrasonic transceiver, the third ultrasonic transceiver, and the fourth ultrasonic transceiver are mounted; a bottom plate facing the top plate in a third direction intersecting the first direction and the second direction; and a plurality of struts extending from the bottom plate in the third direction and supporting the top plate, wherein, when viewed in the third direction, the plurality of struts are positioned so as not to overlap with an imaginary first line connecting the first ultrasonic transceiver and the second ultrasonic transceiver, and an imaginary second line connecting the third ultrasonic transceiver and the fourth ultrasonic transceiver.

18. A wind speed measurement method for measuring wind speed using an ultrasonic anemometer equipped with a first ultrasonic transceiver, a second ultrasonic transceiver located a third distance in a first direction from the first ultrasonic transceiver, and a third ultrasonic transceiver located a fourth distance from the first ultrasonic transceiver in a direction different from the first direction that is shorter than the third distance, the method comprising the steps of: receiving ultrasonic waves transmitted from the first ultrasonic transceiver with the second ultrasonic transceiver and calculating a first wind speed using the transmission and reception results of the ultrasonic waves; receiving ultrasonic waves transmitted from the first ultrasonic transceiver with the third ultrasonic transceiver and calculating a second wind speed using the transmission and reception results of the ultrasonic waves; the method outputs the first wind speed when the difference between the first wind speed and the second wind speed does not satisfy a first condition; and outputs the second wind speed when the difference between the first wind speed and the second wind speed satisfies the first condition.

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