JP5239054B2 - Ultrasonic distance sensor and ultrasonic distance measuring method - Google Patents

Description

  The present invention relates to an ultrasonic distance sensor and an ultrasonic distance measuring method.

Conventionally, ultrasonic distance sensors have been used for measuring the water level of clean water, sewage, rivers, and reservoirs, and measuring levels of chemical tanks and slurry agitation tanks.
As an ultrasonic distance sensor of this type, for example, as shown in Patent Document 1 below, an ultrasonic transmission / reception that emits an ultrasonic pulse to a surface to be measured and receives an ultrasonic pulse reflected by the surface to be measured. A temperature measuring means for measuring the ambient temperature between the wave means, the ultrasonic wave transmitting / receiving means and the surface to be measured at a plurality of locations and outputting a plurality of temperature data; and a plurality of temperature data from the temperature measuring means. A temperature distribution analysis means for analyzing the distribution of the ambient temperature and a propagation speed for measuring the time from the emission to reception of the ultrasonic pulse by the ultrasonic transmission / reception means, and obtaining the propagation speed of the ultrasonic pulse based on the time Based on the ambient temperature distribution obtained by the computing means and the temperature distribution analyzing means, a temperature correcting means for correcting the propagation velocity obtained by the propagation velocity computing means, and a corrected transmission output from the temperature correcting means. Based on the velocity data, by measuring the level of the surface to be measured, a level measuring means for outputting a level measurement signal, the arrangement comprising a known. In this configuration, a plurality of thermometers arranged at predetermined intervals in a direction perpendicular to the surface to be measured are employed as temperature measuring means.
According to this ultrasonic distance sensor, even when the ambient temperature from the ultrasonic transducer to the measurement surface is not uniform, the propagation speed of the ultrasonic wave affected by the ambient temperature is correctly corrected, and more accurate. Level measurement (level measurement) is possible.
JP 2004-251827 A

  However, the conventional ultrasonic distance sensor needs to install a plurality of thermometers on a wall surface or the like, for example, so that there is a problem that installation takes time and cost.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an ultrasonic wave that can be easily and inexpensively installed while enabling accurate level measurement even when the ambient temperature is not uniform. An ultrasonic distance sensor and an ultrasonic distance measuring method using the ultrasonic distance sensor are provided.

In order to solve the above problems, the present invention proposes the following means.
An ultrasonic distance sensor according to the present invention includes ultrasonic transmission / reception means for transmitting an ultrasonic wave and receiving a reflected wave, and measures a time from when the ultrasonic wave is transmitted until the reflected wave is received. Thus, an ultrasonic distance sensor for detecting the distance to the reflecting surface, the temperature formed to be rotatable in order to measure the surface temperature of the structure extending along the propagation direction of the ultrasonic wave. Using the meter, the ultrasonic propagation time measured value from when the ultrasonic wave is transmitted until the reflected wave is received, and the ultrasonic wave propagation velocity calculated from the surface temperature of the structure, A control unit that detects a distance to a reflecting surface, and the control unit calculates a propagation velocity of the ultrasonic wave at a surface temperature of the structure measured by the thermometer, and With a sonic distance sensor and the thermometer A measurement position distance calculation unit that calculates a measurement position distance, which is a distance along the propagation direction of the ultrasonic wave, between the measurement position of the surface temperature of the structure and an adjacent measurement position distance calculation unit; And calculating the propagation time calculation value of the ultrasonic wave in the section using the distance along the propagation direction of the ultrasonic wave in the measurement position section and the propagation speed of the ultrasonic wave. A propagation time calculation value calculation unit that calculates an integrated value of the values, and a reflection that determines that the measurement position exceeds the reflection surface when the integration value of the propagation time calculation value exceeds half of the actual propagation time measurement value. A surface determination unit, wherein the control unit detects a distance to the reflection surface using a first measurement position that is the measurement position determined to have exceeded the reflection surface. It is.

Since the ultrasonic distance sensor according to the present invention includes a thermometer formed to be rotatable, it is possible to measure the surface temperature of the structure extending along the propagation direction of the ultrasonic wave. is there. By calculating the ultrasonic wave propagation speed from the surface temperature, accurate level measurement can be performed even when the ambient temperature is not uniform. Further, since there is no need to install a plurality of thermometers on the surface of the structure as in the prior art, it can be installed easily and at a lower cost than a conventional ultrasonic distance sensor.
Further, when determining whether or not the measurement position exceeds the reflecting surface, the actual propagation time value and the integrated value of the propagation time calculation value are compared. Here, the calculated propagation time is calculated using the propagation speed of the ultrasonic wave at the surface temperature of the structure measured by the thermometer. That is, the integrated value of the calculated propagation time is calculated based on the surface temperatures at a plurality of measurement positions between the ultrasonic distance sensor and the reflecting surface. Therefore, accurate level measurement can be performed even when the ambient temperature is not uniform.
In addition, the structure extending along the propagation direction of the ultrasonic wave is not limited to the structure extending in parallel to the propagation direction, and for example, the structure extending at an angle so as to intersect the propagation direction. Also included are those that extend while curving.

  Further, in the ultrasonic distance sensor according to the present invention, when the control unit determines that the measurement position exceeds the reflection surface, the control unit calculates from the integrated value of the calculated propagation time up to the first measurement position. A first time difference obtained by subtracting half of the actual propagation time value and an integrated value of the calculated propagation time value to the second measurement position, which is the measurement position closest to the first measurement position, are calculated from the half of the actual propagation time value. The ratio of the reduced second time difference is the ratio between the first distance that is the distance between the first measurement position and the reflection surface, and the second distance that is the distance between the reflection surface and the second measurement position. You may detect the distance to the said reflective surface so that it may correspond.

  In this case, since the distance to the reflecting surface is calculated so that the ratio between the first time difference and the second time difference matches the ratio between the first distance and the second distance, the detection accuracy of the distance to the reflecting surface is improved. be able to.

  Further, the ultrasonic distance measuring method according to the present invention is an ultrasonic that detects the distance to the reflection surface using an ultrasonic distance sensor that includes ultrasonic transmission / reception means that transmits ultrasonic waves and receives reflected waves. The ultrasonic distance sensor includes a thermometer formed to be rotatable in order to measure a surface temperature of a structure extending along a propagation direction of the ultrasonic wave, A propagation time measuring step of measuring the ultrasonic propagation time measured from when the ultrasonic wave is transmitted to when the reflected wave is received by the ultrasonic wave transmitting / receiving means; and rotating the thermometer and the temperature A temperature measuring step for measuring the surface temperature of the structure by a meter, a propagation velocity calculating step for calculating a propagation velocity of the ultrasonic wave at the surface temperature of the structure measured by the thermometer, and the ultrasonic distance sensor And the temperature A measurement position distance calculation step of calculating a measurement position distance, which is a distance along a propagation direction of the ultrasonic wave, between the measurement position of the surface temperature of the structure by a meter and a rotation amount of the thermometer; Calculating the propagation time of the ultrasonic wave in the section using the distance along the propagation direction of the ultrasonic wave in the section of the adjacent measurement position and the propagation speed of the ultrasonic wave, and the propagation A propagation time calculation value calculating step for calculating an integrated value of the time calculation value, and when the integrated value of the propagation time calculation value exceeds half of the actual propagation time measurement value, it is determined that the measurement position exceeds the reflecting surface. And a distance detection step of detecting a distance to the reflection surface using the first measurement position that is the measurement position determined to have exceeded the reflection surface.

  According to the ultrasonic distance measuring method according to the present invention, when determining whether or not the measurement position exceeds the reflecting surface, the measured propagation time value and the integrated value of the calculated propagation time value are compared. Here, the calculated propagation time is calculated using the propagation speed of the ultrasonic wave at the surface temperature of the structure measured by the thermometer. That is, the integrated value of the calculated propagation time is calculated based on the surface temperatures at a plurality of measurement positions between the ultrasonic distance sensor and the reflecting surface. Therefore, more accurate level measurement can be performed even when the ambient temperature is not uniform.

The ultrasonic distance sensor according to the present invention can be installed easily and at low cost while enabling accurate level measurement even when the ambient temperature is not uniform.
Further, according to the ultrasonic distance measuring method of the present invention, accurate level measurement can be performed even when the ambient temperature is not uniform.

Hereinafter, an ultrasonic distance sensor according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5.
FIG. 1 is a schematic overall view of an ultrasonic distance sensor according to an embodiment of the present invention. FIG. 2 is a control block diagram of a control unit provided in the ultrasonic distance sensor shown in FIG. FIG. 3 is a diagram for explaining an ultrasonic distance measuring method using the ultrasonic distance sensor shown in FIG.

As shown in FIG. 1, the ultrasonic distance sensor 1 includes ultrasonic transmission / reception means 4 that transmits an ultrasonic wave 2 and receives a reflected wave 3, and receives the reflected wave 3 after transmitting the ultrasonic wave 2. The distance to the reflection surface is detected by measuring the time to do this.
In the present embodiment, the ultrasonic distance sensor 1 is provided on the upper surface of the tank K in which the liquid F such as chemicals and slurry is stored, and reaches the liquid level F1 of the liquid F that is a reflection surface of the ultrasonic wave 2. An example in which the liquid level height Z from the bottom surface of the tank K of the liquid F stored in the tank K is measured (level measurement) by measuring the distance X will be described.

  The tank K communicates with the outside through a flow path (not shown) provided in the lower portion, and the liquid F stored in the tank K flows out of the tank K or flows into the tank K through the flow path. The And the liquid level height Z of the liquid F changes up and down with this outflow or inflow. In the following, it is assumed that the liquid level F1 of the liquid F coincides with the horizontal plane regardless of the liquid level height Z. Further, in the present embodiment, an example in which the inner peripheral surface K1 of the tank K extends in parallel to the vertical direction that is a direction orthogonal to the liquid surface F1 will be described. The inner peripheral surface K1 is preferably made of concrete having a high emissivity, but when the tank K is made of metal having a low emissivity, black tape is applied from the inside of the tank K. Preferably, the inner peripheral surface K1 is processed with a black spray or the like to increase the emissivity.

  As shown in FIGS. 1 and 2, the ultrasonic distance sensor 1 includes the ultrasonic wave transmitting / receiving means 4 and an inner peripheral surface (structure) K1 of a tank K extending along the propagation direction of the ultrasonic wave 2. In order to measure the surface temperature, a radiation thermometer (thermometer) 5 formed to be rotatable, and an actual measurement time Tr of the ultrasonic wave 2 from the transmission of the ultrasonic wave 2 to the reception of the reflected wave 3 And a control unit 6 that detects the distance X to the liquid surface F1 using the propagation speed of the ultrasonic wave 2 calculated from the surface temperature of the inner peripheral surface K1. Furthermore, in the present embodiment, the ultrasonic distance sensor 1 is formed in a box 7 that is fixed to the upper surface of the tank K and opened downward while the motor 7 rotates the radiation thermometer 5. And a housing 8 in which components are fixed.

  The ultrasonic wave transmission / reception means 4 includes a main body 9 in which the control unit 6 is housed, a transmitter 10 that transmits ultrasonic waves 2 toward the liquid surface F1, and a reflected wave 3 reflected by the liquid surface F1. And a receiver 11 for receiving. In the illustrated example, the main body 9 is fixed in the housing 8 by a fixing means (not shown), and the transmitter 10 and the receiver 11 project from the lower surface side of the main body 9 downward. In the example shown in the drawing, the lower surface of the transmitter 10 and the lower surface of the receiver 11 are both flat surfaces parallel to the horizontal plane, and the positions in the vertical direction coincide with each other. The ultrasonic distance sensor 1 of the present embodiment measures the distance X from the virtual reference plane V to the liquid level F1 that includes the lower surface of the transmitter 10 and the lower surface of the receiver 11 and is parallel to the horizontal plane.

The transmitter 10 transmits the ultrasonic wave 2 so that the receiver 11 can receive the reflected wave 3 reflected by the liquid level F1. In the example shown in the figure, the transmitter 10 and the receiver 11 are provided with a gap in the horizontal direction, and the transmitter 10 tilts the receiver 2 toward the receiver 11 side with respect to the vertical direction and emits the ultrasonic waves 2 downward in the vertical direction. send.
The motor 7 is fixedly disposed in the housing 8 by a fixing means (not shown) so that the rotating shaft 12a of the motor shaft 12 is on the virtual reference plane V, and is electrically connected to the control unit 6 via the wiring 7a. Connected. In the present embodiment, the motor 7 includes an encoder 13 (see FIG. 2) that detects a rotation amount of the motor shaft 12 rotated from a preset rotation origin of the motor shaft 12.

As shown in FIG. 1, the radiation thermometer 5 is formed in a rod shape, and a temperature measurement unit 5 a capable of measuring the surface temperature of the inner peripheral surface K <b> 1 of the tank K is provided on one end of the radiation thermometer 5. It has been. The temperature measuring unit 5a can measure the surface temperature of the inner peripheral surface K1 at a position facing the temperature measuring unit 5a by measuring the infrared energy emitted from the inner peripheral surface K1 at the position. . Further, the radiation thermometer 5 is fixed to the motor shaft 12 with the temperature measurement part 5 a facing the inner peripheral surface K <b> 1 of the tank K. In the present embodiment, when the motor shaft 12 is at the rotation origin, the radiation thermometer 5 can measure the surface temperature at the initial measurement position P ₀ that is a position where the virtual reference plane V and the inner peripheral surface K1 intersect. It is preset so as to be in the initial position 5A. The radiation thermometer 5 is electrically connected to the control unit 6 via the wiring 7 a, and the operation is controlled by the control unit 6.

According to the radiation thermometer 5 shown above, since the other end is fixed to the motor shaft 12 having the rotation shaft 12a on the virtual reference plane V, the inner peripheral surface of the tank K as shown in FIG. The surface temperature can be measured sequentially from the upper side to the lower side at a plurality of positions spaced from the initial measurement position P ₀ toward the lower side at K1. In the following, among the position measuring the surface temperature at the inner peripheral surface K1, measuring the position measured in the n-th toward the lower from the initial measuring position P ₀ position P _{n (where,} n is an integer of 0 or more and then, when the n = 0 means the initial measurement position P ₀₎ to. FIG. 3 shows a case where n ≧ 6.

Here, the encoder 13 of the motor 7 sends the total rotation angle θ _n that is the rotation amount of the motor shaft 12 from the rotation origin to the control unit 6. The total rotational angle theta _n is such that the position of the radiation thermometer 5 surface temperature said inner peripheral surface measurable by K1 is moved away from the initial measurement position P ₀ on the lower side of the inner peripheral surface K1, the motor shaft 12 The direction in which the lens rotates is the positive direction. That is, the total rotation angle θ _n indicates the rotation amount of the motor shaft 12 and also indicates the rotation amount of the radiation thermometer 5 from the initial position 5A.

Incidentally, subscript n of the total rotation angle theta _n is, it means that the total rotational angle theta _n are those at the measurement position P _n, the calculated value and the integrated value has been accompanied by the subscript n in the following Similarly, it means that the position is at the measurement position P _n . Further, the integrated value is expressed as Σ [1, n] Q _i when expressing the integrated value of the predetermined value Q _n from the measurement position P ₁ to the measurement position P _n , for example.

As shown in FIGS. 2 and 3, the control unit 6 includes a propagation velocity calculation unit 20 that calculates the propagation velocity of the ultrasonic wave 2 at the surface temperature of the inner peripheral surface K1 measured by the radiation thermometer 5, and a radiation thermometer. a measurement position distance calculating unit 21 that calculates the surface temperature t _n the distance along the vertical direction is measured location distance X _n between the measurement position P _n and the virtual reference surface V of the inner peripheral surface K1 by 5, adjacent A calculated propagation time calculation value calculation unit that calculates the propagation time calculation value T _n of the ultrasonic wave 2 in the section of the measurement positions P _n and P _n−1 and calculates the integrated value Σ [1, n] T _i of the propagation time calculation value. 22 and when the integrated value Σ [1, n] T _i exceeds a half value Tr / 2 which is a half value of the actually measured propagation time, the reflection surface determines that the measurement position P _n exceeds the liquid level F1. And a determination unit 23. Furthermore, in this embodiment, the control unit 6 includes an ultrasonic transmission control unit 24 that transmits the ultrasonic wave 2 to the transmitter 10, and a propagation time measurement unit 25 that measures an actual propagation time value Tr from transmission to reception of the ultrasonic wave 2. A motor drive unit 26, a recording unit 27, and a calculation unit 28 that controls each of the above-described components and measures the liquid level height Z of the liquid F.
In the present embodiment, when the integrated value Σ [1, n] T _i exceeds the half value Tr / 2, the integrated value Σ [1, n] T _i is equal to the half value Tr / 2. Including cases.

The ultrasonic transmission control unit 24 generates the transmission signal that causes the transmitter 10 to transmit the ultrasonic wave 2 based on the control signal from the calculation unit 28, and sends it to the transmitter 10. In addition, the ultrasonic transmission control unit 24 transmits a synchronization signal to the propagation time measurement unit 25 simultaneously with transmission of the transmission signal.
The propagation time measurement unit 25 calculates the propagation time measurement value Tr using the reception signal transmitted when the receiver 11 receives the reflected wave 3 and the synchronization signal. In addition, the propagation time measurement unit 25 sends the measured propagation time actual measurement value Tr to the calculation unit 28.

The motor drive unit 26 controls the rotation of the motor shaft 12 by generating a motor drive signal based on the control signal from the calculation unit 28 and sending it to the motor 7.
The measurement position distance calculation unit 21 acquires the total rotation angle θ _n from the encoder 13, and the total rotation angle θ _n and the previously recorded rotation axis 12 a of the motor shaft 12 to the inner peripheral surface K 1. The measurement position distance _Xn is calculated using the distance a. Further, the measurement position distance calculating unit 21, the value of the measurement location distance X _n-1 at the last measurement position P _n-1 of the measuring position P _n is recorded in advance as the most recent measurement position distance X _A. Then, the measurement position distance calculating unit 21 sends the calculated measurement position distance X _n and last measurement position distance X _A in the propagation time calculation value calculating unit 22.

The propagation velocity calculation unit 20 calculates the propagation velocity Ct _n of the ultrasonic wave 2 at the measurement position P _n using the surface temperature t _n sent from the radiation thermometer 5.
Propagation time calculation value calculating unit 22 uses the measured position distance X _n and last measurement position distance X _A is sent from the measurement position distance calculating section 21, and a propagation velocity Ct _n sent from the propagation velocity calculating section 20 The propagation time calculation value _Tn is calculated. Moreover, the propagation time calculation value calculating section 22, the integrated value sigma to the most recent measurement position _{P n-1} of the measuring position _{P n [1, n-1} ] T i is pre-last accumulation value sigma [1, A ] Is recorded as _Ti . Then, the propagation time calculated value calculation unit 22 calculates and calculates the integrated value Σ [1, n] T _i using the propagation time calculated value T _n and the latest integrated value Σ [1, A] T _i . and it sends it to the integrated value Σ [1, n] _{T i} the reflective surface determining unit 23.

The reflecting surface determination unit 23 first determines whether the integrated value Σ [1, n] T _i exceeds the half value Tr / 2, and the integrated value Σ [1, n] T _i is determined to be the half value Tr /. If it is determined that the number does not exceed 2, an undetected signal is sent to the calculation unit 28. Meanwhile, the integrated value Σ [1, n] _{if T i} is determined to exceed the half value Tr / 2 is further the integrated value Σ [1, n] _{T i} is the half value Tr / 2 Determine if greater than. Then, when the integrated value Σ [1, n] _Ti is larger than the half value Tr / 2, the reflecting surface determining unit 23 sends a mismatch detection signal to the calculating unit 28, and the integrated value Σ [1, n ] If _{T i} is not greater than the half value Tr / 2, that is when the integrated value Σ [1, n] _{T i} is coincident with the half value Tr / 2, and sends a coincidence detection signal to the arithmetic unit 28.

  The calculation unit 28 controls the ultrasonic wave transmission control unit 24, the motor drive unit 26, and the radiation thermometer 5 so as to detect the liquid level height Z of the liquid F in the tank K for each preset detection period. To control each component. Further, the propagation time measurement value Tr is sent from the propagation time measurement unit 25 to the calculation unit 28, and the calculation unit 28 calculates the half value Tr / 2 from the propagation time measurement value Tr to reflect the reflection surface determination unit 23. To send.

The arithmetic unit 28, when the coincidence detection signal and the mismatch detection signal from the reflective surface determining unit 23 is sent, obtains the measurement position distance X _n and last measurement position distance X _A from the measurement position distance calculating section 21 Then, the integrated value Σ [1, n] _Ti and the latest integrated value Σ [1, A] _Ti are acquired from the propagation time calculated value calculation unit 22, and the distance X to the liquid level F1 is detected using these values. . A specific method for detecting the distance X will be described later. Further, the calculation unit 28 calculates the liquid level height Z of the liquid F using the detected distance X to the liquid level F1 and the distance Y from the virtual reference plane V recorded in advance to the bottom surface of the tank K. taking measurement. And the calculating part 28 records the liquid level height Z of the liquid F on the recording part 27, or displays on the display part 29 comprised with the monitor etc. electrically connected to the calculating part 28, etc. Process appropriately.

Next, an example of an ultrasonic distance measuring method for detecting the distance X of the liquid F in the tank K to the liquid level F1 using the ultrasonic distance sensor 1 described above will be described. In the following example, a case where the ultrasonic distance sensor 1 automatically detects the distance X every preset detection period will be described.
FIG. 4 is a first half of a flowchart showing an example of an ultrasonic distance measuring method using the ultrasonic distance sensor shown in FIG. FIG. 5 is the latter half of the flowchart shown in FIG.

First, the calculation unit 28 performs initial setting as shown below (initial setting step; S10). First, the calculating part 28 sends a control signal to the motor drive part 26, rotates the motor shaft 12 to the rotation origin, and rotates the radiation thermometer 5 to the initial position 5A (S11). In addition, the calculation unit 28 uses the latest integrated value Σ [1, A] T _i recorded in the measurement position distance calculation unit 21 and the latest measurement position distance X _A recorded in the propagation time calculation value calculation unit 22. Each is initialized to 0 (S12).

  Next, the propagation time measurement value Tr of the ultrasonic wave 2 from when the ultrasonic wave 2 is transmitted until the reflected wave 3 is received is measured by the ultrasonic wave transmitting / receiving means 4 (propagation time measuring step; S20). At this time, the calculation unit 28 sends a control signal to the ultrasonic wave transmission control unit 24 and causes the ultrasonic wave transmission control unit 24, the propagation time measurement unit 25, and the ultrasonic wave transmission / reception means 4 to measure the propagation time actual measurement value Tr. (S21), this propagation time measured value Tr is sent to the calculation unit 28. In addition, the calculation unit 28 that has acquired the actual propagation time value Tr calculates the half value Tr / 2 (S22) and sends it to the reflection surface determination unit 23.

Next, the radiation thermometer 5 is rotated and the surface temperature of the inner peripheral surface K1 is measured by the radiation thermometer 5 (temperature measurement step; S30).
More specifically, first, the calculation unit 28 sends a control signal to the motor drive unit 26 and rotates the radiation thermometer 5 by rotating the motor shaft 12 (S31). At this time, the calculation unit 28 rotates the motor shaft 12 by a predetermined unit rotation amount set in advance, and moves the position where the surface temperature can be measured by the radiation thermometer 5 on the inner peripheral surface K1 to the lower side. .

Next, the calculation unit 28 sends a control signal to the radiation thermometer 5, and the surface temperature of the inner peripheral surface K1 is measured by the radiation thermometer 5 (S32). At this time, the position where the surface temperature can be measured by the radiation thermometer 5 on the inner peripheral surface K1 is moved downward from the initial measurement position P ₀ , that is, the radiation thermometer 5 is moved from the initial measurement position P _0. The surface temperature t ₁ at the _first measurement position P ₁ is measured downward. Thereafter, the radiation thermometer 5 sends the measured surface temperature t ₁ to the propagation velocity calculation unit 20.

Next, the propagation speed of the ultrasonic wave 2 at the surface temperature of the inner peripheral surface K measured by the radiation thermometer 5 is calculated (propagation speed calculation step; S50). At this time, the propagation velocity calculation unit 20 uses the surface temperature t ₁ sent from the radiation thermometer 5 to calculate the propagation velocity Ct ₁ (m / s) at the surface temperature t ₁ (° C.).
Ct ₁ = 331.5 + 0.607t ₁
Calculate as

Then, the radiation thermometer 5 is to calculate the measurement position distance X ₁ in the measurement position P ₁ of measuring the surface temperature t ₁ (measurement position distance calculating step; S60). At this time, the measurement position distance calculation unit 21 obtains the total rotation angle θ ₁ of the motor shaft 12 after the temperature measurement process from the encoder 13 (S61), and the inner position is calculated from the total rotation angle θ ₁ and the rotation shaft 12a. The measurement position distance X ₁ is calculated as X ₁ = a · tan θ ₁ using the distance a to the circumferential surface K1 (S62). Thereafter, the measurement position distance calculation unit 21 sends the measurement position distance X ₁ and the latest measurement position distance X _A to the propagation time calculation value calculation unit 22.

Next, the propagation time calculation value T ₁ of the ultrasonic wave 2 in the section is calculated using the distance ΔX ₁ along the vertical direction of the section of the adjacent measurement positions P ₁ and P ₀ and the propagation velocity Ct _1, and The integrated value Σ [1,1] _Ti is calculated (propagation time calculation value calculation step; S70). At this time, first, the propagation time calculation value calculation unit 22 uses the measurement position distance X ₁ and the latest measurement position distance X _A received from the measurement position distance calculation unit 21 as the distance ΔX ₁ of the section, ΔX ₁ = X ₁ −X _A is calculated (S 71). Next, the propagation time calculation value calculation unit 22 calculates T ₁ = ΔX ₁ / Ct ₁ as the propagation time calculation value T ₁ of the ultrasonic wave 2 in the section (S72). Next, the propagation time calculation value calculation unit 22 calculates Σ [1,1] T _i = ΣT _A + T ₁ as the integrated value Σ [1,1] T _i (S73). Then, the propagation time calculation value calculating unit 22 sends the accumulated value Σ [1,1] _{T i} on the reflection surface determination unit 23.

Then, the integrated value sigma [1, 1] measurement position P ₁ when T _i has exceeded the half value Tr / 2 is determined to exceed the fluid level F1, detects a distance X to the liquid surface F1 ( Distance detection step; S80). At this time, first, the reflecting surface determination unit 23 compares the transmitted integrated value Σ [1,1] _Ti with the half value Tr / 2 transmitted from the calculation unit 28 in the propagation time measurement step. (S81), when the integrated value Σ [1,1] T _i does not exceed the half value Tr / 2, an undetected signal is indicated, and the integrated value Σ [1,1] T _i is the half value. sends a coincidence detection signal when a match with the value Tr / 2, the integrated value Σ [1,1] T _i mismatch detection signal when is greater than the half value Tr / 2, respectively calculating section 28 .
Here, processing by the calculation unit 28 when each signal is received from the reflection surface determination unit 23 will be described in detail below.

First, when an undetected signal is received, the calculation unit 28 first causes the measurement position distance calculation unit 21 to record the measurement position distance X ₁ calculated as the most recent measurement position distance X _A and the measurement position distance calculation unit. 21, the most recent integrated value Σ [1, a] the integrated value calculated as _{T i} sigma records the _{[1,1] T i (S82)} . Then, the calculating part 28 controls each component so that it may repeat from a temperature measurement process (S30) to a propagation time calculation value calculation process (S70).

Here, since the radiation thermometer 5 is rotated by the unit rotation amount in the temperature measurement process, the measurement position to be a target for calculating the integrated value is determined by repeating the process from the temperature measurement process to the propagation time calculation value calculation process. Gradually, the measurement positions P ₁ , P ₂ , P ₃ ... Move downward. Hereinafter, the integrated value Σ [1, b] T _i calculated when the temperature measurement step to the propagation time calculation value calculation step is performed b times (where b is an integer equal to or greater than 1) is the half value Tr. Explanation will be made assuming that it exceeds / 2. In the following, it referred to the measurement position P _b which is judged it exceeds the liquid surface F1 and the first measurement position P _b, the most recent measurement position P _b-1 of the first measurement position P _b second measurement position P _{b- 1} is called.

When the calculation unit 28 receives the coincidence detection signal and the mismatch detection signal, the calculation unit 28 calculates the distance X to the liquid level F1 as described below (S83). That is, the integrated value up to the first measuring position _{P b Σ [1, b]} T and the first time difference obtained by subtracting the half value Tr / 2 from _i, the half value Tr / 2 from the second measuring position _{P b-} the integrated value Σ to ₁ ratio of the second time difference obtained by subtracting the [1, b-1] T i is a first distance is a distance between the first measurement position P _b and the liquid level F1, the liquid level F1 And the above-mentioned distance X is calculated by proportionally allocating so as to coincide with the ratio of the second distance that is the distance between the second measurement position P _b-1 and the second measurement position P _b-1 .

In more detail, first, computing unit 28, measurement position distance calculating unit 21 obtains the measurement position distance X _b and immediate measurement position distance X _A from the integrated value sigma [1 from the propagation time calculation value calculating section 22, b] _{T i} and last integrated value Σ [1, a] respectively acquires _{T i.} At this time, the most recent measurement position distance _{X A} and last integrated value Σ [1, A] _{T i} is set to 0 when b = 1 as described above is (S12). Furthermore, when b> 1 is set to the measuring position distance and the accumulated value immediately before calculating the measured position distance X _b and the integrated value Σ [1, b] T _i repeatedly that (S82). Thus, the most recent measurement position distance X _A and last integrated value Σ [1, A] T _i is in any case has a respective values in the second measurement position P _b-1.

And the calculating part 28 calculates the distance X to the liquid level F1 using following Numerical formula (1).
(Σ [1, b] T _i −Tr / 2): (Tr / 2−Σ [1, A] T _i ) = (X _b −X): (X−X _A ) (1)
In the mathematical formula (1), the left side represents the ratio between the first time difference and the second time difference, and the right side represents the ratio between the first distance and the second distance.
When the coincidence detection signal is transmitted, since the integrated value Σ [1, b] _Ti and the half value Tr / 2 coincide with each other, the computing unit 28 computes the formula (1). Without calculating, the distance X to the liquid level F1 is calculated as X = _Xb .
This is the end of the distance detection process.

  Finally, the calculation unit 28 calculates the liquid level height Z = Y−X of the liquid F based on the distance X calculated in the distance detection step and the distance Y from the virtual reference plane V to the bottom surface of the tank K. (Level measurement step; S90).

  Since the ultrasonic distance sensor 1 described above includes the radiation thermometer 5 formed to be rotatable, a plurality of thermometers are installed on the surface of the tank K or the like as in the prior art. There is no need. Therefore, it can be installed easily and at a lower cost than conventional ultrasonic distance sensors.

Further, when determining whether or not the measurement position exceeds the liquid level, the actual propagation time value is compared with the integrated value of the calculated propagation time value. Here, the calculated propagation time is calculated using the propagation speed of the ultrasonic wave 2 at the surface temperature of the inner peripheral surface K1 measured by the radiation thermometer 5. That is, the integrated value of the propagation time calculation values is calculated based on the surface temperatures at a plurality of measurement positions between the virtual reference plane V and the liquid level F1. Therefore, more accurate level measurement can be performed even when the ambient temperature is not uniform.
Further, since the distance X to the liquid level F1 is calculated so that the ratio between the first time difference and the second time difference matches the ratio between the first distance and the second distance, detection of the distance X to the liquid level F1 is detected. Accuracy can be improved.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the embodiment, in the distance detection step, the calculation unit 28 determines the distance to the liquid level F1 so that the ratio between the first time difference and the second time difference matches the ratio between the first distance and the second distance. Was calculated. However, not limited to this, for example, it may be a weighted average of the measurement location distance X _b-1 at the measurement position a distance X _b and the second measurement position P _b-1 in the first measurement position P _b.

Moreover, in the said embodiment, although the motor 7 provided with the encoder 13 was employ | adopted as a means to rotate the radiation thermometer 5, the control part 6 shall acquire total rotation angle (theta) _n from the encoder 13, Not limited. For example, a stepping motor may be adopted as means for rotating the radiation thermometer 5 and the total rotation angle θ _n may be acquired from the motor control signal sent by the motor driving unit 26 of the stepping motor.

In the embodiment, the measurement position distance calculation unit 21 uses the distance a from the rotation shaft 12a of the motor shaft 12 to the inner peripheral surface K1 and the total rotation angle θ _{n as} the measurement position distance X _n. Although calculated, it is not limited to this. For example, the measurement position a distance X _n corresponding to the total rotational angle theta _n is previously recorded in the measurement position distance calculating unit 21, measurement position distance calculating unit 21, measurement position a distance corresponding, based on the total rotation angle theta _{n Xn} may be referred to. In this case, even if the inner peripheral surface K1 of the tank K extends while curving with respect to the direction orthogonal to the liquid surface F1, or even when inclined with respect to the orthogonal direction, the measurement position distance X _n Can be calculated accurately.

  The ultrasonic distance sensor 1 and the ultrasonic distance measuring method according to the present invention are used for level measurement of the tank K storing the liquid F, that is, for level measurement of a chemical tank and a slurry agitation tank. However, the ultrasonic distance sensor 1 may be used for measuring the water level of water, sewage, rivers, and reservoirs.

  In addition, it is possible to appropriately replace the constituent elements in the embodiment with known constituent elements without departing from the spirit of the present invention, and the above-described modified examples may be appropriately combined.

1 is a schematic overall view of an ultrasonic distance sensor according to an embodiment of the present invention. It is a control block diagram of the control part with which the ultrasonic distance sensor shown in FIG. It is a figure for demonstrating the ultrasonic distance measuring method using the ultrasonic distance sensor shown in FIG. It is the first half part of the flowchart which shows an example of the ultrasonic distance measuring method using the ultrasonic distance sensor shown in FIG. It is the latter half part of the flowchart shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic distance sensor 2 Ultrasonic wave 3 Reflected wave 4 Ultrasonic wave transmission / reception means 5 Radiation thermometer (thermometer)
6 Control part 20 Propagation speed calculation part 21 Measurement position distance calculation part 22 Propagation time calculation value calculation part 23 Reflective surface judgment part 24 Ultrasonic wave transmission control part 25 Propagation time measurement part F1 Liquid surface (reflective surface)
K1 inner surface (structure)
Ct ₁ , Ct _n propagation velocity P ₀ , P ₁ , P ₂ , P ₃ , P _n−1 , P _n measurement position P _b first measurement position P _b-1 second measurement position t ₁ , t _n−1 , t _n surface temperature T ₁ , T _n propagation time calculation value Tr propagation time measurement value Tr / 2 half value (half of propagation time measurement value)
X Distance to the liquid level (distance to the reflective surface)
X ₁ , X _b , X _n , X _n-1 measurement position distances Σ [1, 1] T _i , Σ [1, b-1] T _i , Σ [1, b] T _i , Σ [1, n ] T _i , Σ [1, n−1] T _i integrated value of propagation time calculation value ΔX ₁ distance θ ₁ , θ _n total rotation angle between adjacent measurement positions (from a predetermined initial position of the thermometer Rotation amount)

Claims (3)

An ultrasonic wave transmission / reception means for transmitting an ultrasonic wave and receiving a reflected wave is provided, and a distance to the reflecting surface is detected by measuring a time from when the ultrasonic wave is transmitted until the reflected wave is received. An ultrasonic distance sensor,
In order to measure the surface temperature of the structure extending along the propagation direction of the ultrasonic wave, a thermometer formed to be rotatable,
Using the ultrasonic propagation time measured value from when the ultrasonic wave is transmitted until the reflected wave is received, and the ultrasonic wave propagation velocity calculated from the surface temperature of the structure, to the reflective surface A control unit for detecting the distance of
Equipped with a,
The controller is
A propagation velocity calculation unit for calculating the propagation velocity of the ultrasonic wave at the surface temperature of the structure measured by the thermometer;
The measurement position distance, which is the distance along the propagation direction of the ultrasonic wave, between the ultrasonic distance sensor and the measurement position of the surface temperature of the structure by the thermometer is used as the rotation amount of the thermometer. A measurement position distance calculation unit to calculate based on,
Using the distance along the propagation direction of the ultrasonic wave of the adjacent measurement position section and the propagation speed of the ultrasonic wave, the propagation time calculation value of the ultrasonic wave in the section is calculated, and the propagation time is calculated. A propagation time calculated value calculation unit for calculating the integrated value of the calculated values;
When the integrated value of the calculated propagation time exceeds half of the actual measured propagation time, a reflective surface determination unit that determines that the measurement position exceeds the reflective surface;
With
The ultrasonic distance sensor , wherein the control unit detects a distance to the reflection surface using a first measurement position which is the measurement position determined to have exceeded the reflection surface . The ultrasonic distance sensor according to claim 1 ,
The controller is
When it is determined that the measurement position exceeds the reflecting surface,
A first time difference obtained by subtracting half of the propagation time actual measurement value from the integrated value of the propagation time calculation values up to the first measurement position, and a second measurement position that is the measurement position closest to the first measurement position. The ratio of the integrated value of the calculated propagation time to the second time difference obtained by subtracting from the half of the actually measured propagation time,
The distance from the first measurement position to the reflection surface is equal to the ratio of the first distance that is the distance between the reflection surface and the second distance that is the distance between the reflection surface and the second measurement position. An ultrasonic distance sensor for detecting a distance. An ultrasonic distance measuring method for detecting a distance to a reflecting surface using an ultrasonic distance sensor including an ultrasonic wave transmitting / receiving means for transmitting an ultrasonic wave and receiving a reflected wave,
The ultrasonic distance sensor includes a thermometer formed to be rotatable in order to measure the surface temperature of a structure extending along the propagation direction of the ultrasonic wave,
A propagation time measuring step of measuring the ultrasonic propagation time measured value from when the ultrasonic wave is transmitted until the reflected wave is received by the ultrasonic wave transmitting and receiving means;
A thermometry step of rotating the thermometer and measuring the surface temperature of the structure by the thermometer;
A propagation velocity calculating step of calculating a propagation velocity of the ultrasonic wave at the surface temperature of the structure measured by the thermometer;
The measurement position distance, which is the distance along the propagation direction of the ultrasonic wave, between the ultrasonic distance sensor and the measurement position of the surface temperature of the structure by the thermometer is used as the rotation amount of the thermometer. A measurement position distance calculating step to calculate based on;
Using the distance along the propagation direction of the ultrasonic wave of the adjacent measurement position section and the propagation speed of the ultrasonic wave, the propagation time calculation value of the ultrasonic wave in the section is calculated, and the propagation time is calculated. A propagation time calculated value calculating step for calculating the integrated value of the calculated values;
When the integrated value of the calculated propagation time exceeds half of the actually measured propagation time, it is determined that the measurement position has exceeded the reflection surface and the measurement position that has been determined to have exceeded the reflection surface. A distance detection step of detecting a distance to the reflection surface using the first measurement position;
An ultrasonic distance measuring method characterized by comprising:

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