JP2013231679A - Temperature measurement device and temperature measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately measure the temperature of a measuring target space without being affected by a humidity when the temperature of the measuring target space is measured by using a sound wave.SOLUTION: When the temperature of a measuring target space is measured based on sound wave propagation time between a sound wave transmitter and a sound wave receiver arranged by sandwiching the measuring target space and a relative humidity detected by a humidity sensor, an initial value of an original temperature is set (ST102). Temperature correction processing is performed to obtain a corrected temperature from the original temperature, the propagation time, and the relative humidity (ST104 to ST106, ST108 to ST110). Whether the obtained temperature has converged is determined (ST111). The temperature correction processing (ST108 to ST110) is repeated until the convergence is determined to obtain the temperature of the measuring target space.

Description

  The present invention relates to a temperature measuring device and a temperature measuring method for measuring the temperature of a measurement target space based on the speed of sound.

  A technique for obtaining the temperature of the measurement target space using the principle that the speed of sound in the air changes according to the temperature is known (see Patent Documents 1 and 2). Such a temperature measurement technique based on the speed of sound is convenient when it is difficult to directly install a temperature sensor in the space to be measured, such as a reflow furnace. In addition, for example, when it is desired to obtain an average temperature of an entire wide space such as a store, a warehouse, or a greenhouse, there is an advantage that the temperature can be obtained accurately and efficiently without installing a large number of temperature sensors.

  In addition, since the speed of sound in the air changes according to humidity, in order to perform temperature measurement that is not affected by humidity, the humidity sensor measures the humidity of the measurement target space and based on the measured humidity value. A technique for correcting the speed of sound is known (see Patent Document 1).

Japanese Patent Laid-Open No. 1-255096 JP 2010-139251 A

  Now, what affects the speed of sound is the water vapor pressure (water vapor amount) in the air, while what is detected by the humidity sensor is generally the relative humidity, that is, the water vapor pressure relative to the saturated water vapor pressure (saturated water vapor amount) ( The amount of water vapor). For this reason, in order to perform sound velocity correction with humidity with high accuracy, it is necessary to know the saturated water vapor pressure in addition to the relative humidity obtained by the humidity sensor. However, since the saturated water vapor pressure changes according to the temperature, it is necessary to know the temperature in order to obtain the saturated water vapor pressure, and eventually the temperature is necessary for temperature measurement. Cannot be asked.

  On the other hand, a method of providing a temperature sensor and obtaining the saturated water vapor pressure from the temperature detected by the temperature sensor is also conceivable. However, this requires a temperature sensor in addition to the humidity sensor, which causes a problem of increased cost. Furthermore, the temperature measurement technique based on the speed of sound is used when it is difficult to install a temperature sensor in the measurement target space as described above, and therefore the temperature sensor is installed on the wall surface facing the measurement target space. However, since the temperature near the wall surface detected by the temperature sensor may be significantly different from the average temperature of the entire measurement target space, there arises a problem that the measurement accuracy cannot be sufficiently increased.

  The present invention has been devised to solve such problems of the prior art, and its main purpose is to be affected by humidity when measuring the temperature of the measurement object space based on the speed of sound. It is another object of the present invention to provide a temperature measuring device and a temperature measuring method configured to be able to measure the temperature of the measurement target space with high accuracy.

  The temperature measurement device of the present invention is a temperature measurement device that measures the temperature of a measurement target space based on the speed of sound, and includes a sound wave transmitter and a sound wave receiver that are disposed across the measurement target space, and the measurement A humidity sensor that detects the relative humidity of the target space, a propagation time acquisition unit that acquires a propagation time of a sound wave between the acoustic wave transmitter and the acoustic wave receiver, and a propagation time acquired by the propagation time acquisition unit And a temperature acquisition unit that obtains the temperature of the measurement target space based on the relative humidity detected by the humidity sensor, and the temperature acquisition unit sets an initial value of the original temperature, A temperature correction process for obtaining a temperature corrected from the temperature, the propagation time, and the relative humidity is repeated until the temperature of the measurement target space is obtained.

  Further, the temperature measurement method of the present invention is a temperature measurement method for measuring the temperature of the measurement target space using sound waves, and between the sound wave transmitter and the sound wave receiver arranged with the measurement target space interposed therebetween. A propagation time acquisition step of acquiring the propagation time of the sound wave at the time, a temperature acquisition step of acquiring the temperature of the measurement target space based on the propagation time acquired in the propagation time acquisition step and the relative humidity detected by the humidity sensor; The temperature acquisition step includes an initial value setting step for setting an initial value of the original temperature, a temperature correction step for obtaining a temperature corrected from the original temperature, the propagation time, and the relative humidity, A convergence determination step for determining whether or not the temperature obtained in the temperature correction step has converged, and the measurement target is repeated by repeating the temperature correction step until it is determined that the temperature has been converged in the convergence determination step. Sky A configuration in which determination of the temperature.

  According to the present invention, the corrected temperature obtained by the temperature correction process satisfies the conditions of propagation time and relative humidity, that is, the temperature at which the sound velocity is corrected by humidity, and is a true temperature from the original temperature. By repeating this temperature correction process, it is possible to approach the true temperature. This makes it possible to measure the temperature of the measurement target space with high accuracy without being affected by humidity. In addition, it is not always necessary to provide a temperature sensor, and an increase in cost can be suppressed.

1 is an overall configuration diagram showing a temperature measuring device according to a first embodiment. Explanatory drawing showing temperature measurement error obtained from sound velocity Flow chart showing the procedure of temperature acquisition processing performed by the controller Overall configuration diagram showing a temperature measuring apparatus according to a second embodiment Overall configuration diagram showing a modification of the temperature measuring device

  A first invention made to solve the above-described problem is a temperature measurement device for measuring the temperature of a measurement target space based on the speed of sound, and a sound wave transmitter and a sound wave arranged with the measurement target space interposed therebetween A receiver, a humidity sensor that detects relative humidity of the measurement target space, a propagation time acquisition unit that acquires a propagation time of a sound wave between the sound wave transmitter and the sound wave receiver, and the propagation time A temperature acquisition unit that obtains the temperature of the measurement target space based on the propagation time acquired by the acquisition unit and the relative humidity detected by the humidity sensor, and the temperature acquisition unit sets an initial value of the original temperature After that, the temperature correction process for obtaining the temperature corrected from the original temperature, the propagation time, and the relative humidity is repeated until the temperature of the measurement target space is obtained.

  According to this, the corrected temperature obtained by the temperature correction processing satisfies the conditions of propagation time and relative humidity, that is, the temperature at which the sound velocity has been corrected by humidity, and is closer to the true temperature than the original temperature. Then, it is possible to approach the true temperature by repeating this temperature correction process. This makes it possible to measure the temperature of the measurement target space with high accuracy without being affected by humidity. In addition, it is not always necessary to provide a temperature sensor, and an increase in cost can be suppressed.

  In the second invention, the temperature acquisition unit obtains a saturated water vapor pressure from the original temperature in the temperature correction process, obtains a water vapor pressure from the saturated water vapor pressure and the relative humidity, The temperature is corrected from the propagation time.

  According to this, it is possible to obtain the temperature that satisfies the conditions of propagation time and relative humidity, that is, the temperature at which the sound velocity is corrected by the humidity.

  Moreover, 3rd invention sets the said temperature acquisition part as the initial value of the said original temperature for the temperature calculated | required from the said propagation time supposing dry air.

  According to this, it is possible to easily set the initial value of the original temperature, and it is possible to reduce the processing load in the temperature acquisition unit and increase the processing speed.

  The fourth aspect of the invention further includes a temperature sensor that detects a temperature in the vicinity of the wall surface facing the measurement target space, and the temperature acquisition unit sets the temperature detected by the temperature sensor to the initial value. The configuration.

  According to this, since the temperature correction process can be started at a value close to the actual temperature of the measurement target space, it is possible to reduce the number of repetitions until convergence is achieved by repeating the temperature correction process, and the process in the temperature acquisition unit The processing load can be reduced and the processing speed can be increased.

  The fifth aspect of the present invention further includes an atmospheric pressure sensor that detects an atmospheric pressure of the measurement target space, and the temperature acquisition unit obtains the temperature of the measurement target space based on the atmospheric pressure detected by the atmospheric pressure sensor. To do.

  According to this, the temperature of the measurement object space can be measured with higher accuracy.

  Further, the sixth invention is a temperature measurement method for measuring the temperature of the measurement target space using sound waves, and between the sound wave transmitter and the sound wave receiver arranged with the measurement target space interposed therebetween. A propagation time acquisition step of acquiring the propagation time of the sound wave, and a temperature acquisition step of acquiring the temperature of the measurement target space based on the propagation time acquired in this propagation time acquisition step and the relative humidity detected by the humidity sensor, The temperature acquisition step includes an initial value setting step for setting an initial value of the original temperature, a temperature correction step for obtaining a temperature corrected from the original temperature, the propagation time, and the relative humidity, and the temperature A convergence determination step for determining whether or not the temperature obtained in the correction step has converged, and the temperature correction step is repeated until it is determined that the temperature has been converged in the convergence determination step. Temperature And Mel configuration.

  According to this, the corrected temperature obtained by the temperature correction processing satisfies the conditions of propagation time and relative humidity, that is, the temperature at which the sound velocity has been corrected by humidity, and is closer to the true temperature than the original temperature. Then, it is possible to approach the true temperature by repeating this temperature correction process. This makes it possible to measure the temperature of the measurement target space with high accuracy without being affected by humidity. In addition, it is not always necessary to provide a temperature sensor, and an increase in cost can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is an overall configuration diagram showing a temperature measurement device according to the first embodiment. This temperature measurement device 1 measures the temperature of the measurement target space S based on the speed of sound, and includes a transmission side device 3 having an ultrasonic transmitter 2 and a reception side having an ultrasonic receiver 4. Acquired by the device 5, the humidity sensor 6 for detecting the humidity of the measurement target space S, the controller 7 for controlling the transmission side device 3 and the reception side device 5 and acquiring the temperature of the measurement target space S, and the controller 7 And a display device 8 for displaying the temperature of the measured measurement space S.

  The ultrasonic wave transmitter 2 and the ultrasonic wave receiver 4 are arranged to face each other across the measurement target space S, and the ultrasonic wave transmitted from the ultrasonic wave transmitter 2 is transmitted by the ultrasonic wave receiver 4. Received. The ultrasonic wave transmitter 2 has a transducer for wave transmission. The ultrasonic receiver 4 has a vibrator for receiving waves.

  In addition, the temperature measuring device 1 includes a synchronization signal transmitter 11 in the transmission side device 3 in order to synchronize the transmission operation of the ultrasonic transmitter 2 and the reception operation of the ultrasonic receiver 4. The receiving device 5 includes a synchronization signal receiver 12. The synchronization signal transmitter 11 and the synchronization signal receiver 12 are arranged opposite to each other with the measurement target space S interposed therebetween, and the synchronization signal transmitted from the synchronization signal transmitter 11 by radio waves is received by the synchronization signal receiver 12. The Note that transmission / reception of the synchronization signal is not limited to radio waves, and visible light or infrared light can also be used.

  In addition to the ultrasonic transmitter 2 and the synchronization signal transmitter 11, the transmission-side device 3 includes a CPU 13 and an amplifier 14 that amplifies a drive signal from the CPU 13 and drives the ultrasonic transmitter 2. ing.

  In the transmission side device 3, in response to a transmission command from the controller 7, a drive signal is output from the CPU 13 to the synchronization signal transmitter 11, and simultaneously, a drive signal is output from the CPU 13 to the amplifier 14. As a result, radio waves are transmitted from the synchronization signal transmitter 11 toward the synchronization signal receiver 12, and at the same time, ultrasonic waves are radiated from the ultrasonic transmitter 2 toward the ultrasonic receiver 4. At this time, the drive signal output from the CPU 13 to the amplifier 14 is a rectangular wave signal having a predetermined frequency (for example, 40 kHz). The rectangular wave signal is output for a predetermined time, and the rectangular wave signal is output from the ultrasonic transmitter 2. The ultrasonic wave based on is emitted.

  In addition to the ultrasonic receiver 4 and the synchronization signal receiver 12, the receiving-side device 5 includes a CPU 15, an amplifier 16 that amplifies a signal from the ultrasonic receiver 4, and a signal from the amplifier 16 as A / And an A / D conversion unit 17 that performs D conversion and outputs the result to the CPU 15.

  In the receiving side device 5, when the synchronization signal receiver 12 receives the synchronization signal from the synchronization signal transmitter 11, the CPU 15 starts measuring time with a timer. After that, when the ultrasonic wave from the ultrasonic wave transmitter 2 is received by the ultrasonic wave receiver 4, the signal is input to the CPU 15 via the amplifier 16 and the A / D converter 17. The CPU (propagation time acquisition unit) 15 determines that the ultrasonic wave has arrived when the input signal exceeds a certain value, and ends the time measurement by the timer. Then, the ultrasonic wave propagation time is calculated by subtracting the ultrasonic wave transmission / reception rise time and the signal transmission delay time from the time counted by the timer, and the ultrasonic wave propagation time is output to the controller 7.

  The controller (temperature acquisition unit) 7 acquires the ultrasonic wave propagation time from the wave receiving side device 5, acquires the humidity detected by the humidity sensor 6 via the wave transmitting side device 3, and this ultrasonic wave propagation A process of acquiring the temperature of the measurement target space S based on time and humidity is performed.

  Next, problems in measuring the temperature of the measurement target space S based on the speed of sound and an outline of the temperature acquisition process performed by the controller 7 in this embodiment will be described.

The speed of sound C (m / sec) is calculated by the following equation 1 from the propagation distance L (m) of ultrasonic waves and the propagation time t (sec).
C = L / t (Formula 1)
Here, the propagation distance L is a separation distance between the ultrasonic transmitter 2 and the ultrasonic receiver 4. The propagation time t is calculated by the CPU 15 of the receiving device 5 as described above.

On the other hand, the speed of sound C (m / sec) in the dry air at the temperature T can be calculated from the temperature T by either of the following equations 2-1 and 2-2.
C = 331.45 + 0.607 × T (Formula 2-1)

The following Expression 3 is obtained from Expression 1 and Expression 2-1, and the temperature T can be obtained from this Expression 3.
T = (C-331.45) /0.607
= (L / t-331.45) /0.607 (Formula 3)

  However, the sound velocity C shown in Equation 1 is actually measured and varies depending on the humidity, so that it usually differs from the sound velocity C in dry air shown in Equation 2-1. For this reason, the temperature T obtained from Equation 3 includes an error due to humidity, and this error increases as the humidity increases.

  FIG. 2 is an explanatory diagram showing a temperature measurement error obtained from the sound velocity. As apparent from FIG. 2, the temperature measurement error obtained from the sound velocity increases as the relative humidity RH increases. Therefore, if necessary, it is necessary to correct the sound velocity by humidity and obtain the temperature T based on the sound velocity in the dry air obtained by this.

ここで、γｗは水蒸気の定圧比熱と定積比熱との比率（≒１．３３）、γａは乾燥空気の定圧比熱と定積比熱との比率（≒１．４０）、Ｈは気圧（Ｐａ）である。 Here, the relationship between the speed of sound C in the dry air and the speed of sound C ′ in the air containing water vapor that becomes the water vapor pressure P (Pa) is expressed by the following Expression 4. Equation 4 corrects the speed of sound by the water vapor pressure P.

Here, γw is the ratio of the constant pressure specific heat and the constant volume specific heat of water vapor (≈1.33), γa is the ratio of the constant pressure specific heat and the constant volume specific heat of dry air (≈1.40), and H is the atmospheric pressure (Pa). It is.

In Equation 4, the sound velocity C ′ in the air containing water vapor is an actual measurement value (L / t) calculated from the propagation time t as shown in Equation 1, and Equation 1, Equation 2-1, and Equation 4 are used. The following formula 5 can be obtained from According to Equation 5, the temperature T can be calculated from the propagation time t and the water vapor pressure P by omitting the process for obtaining the sound speed.

  However, this equation 5 includes the water vapor pressure P as a variable. In order to obtain the temperature T using this equation 5, it is necessary to know the water vapor pressure P.

Here, in this embodiment, as shown in FIG. 1, the humidity sensor 6 is provided, and the water vapor pressure P may be obtained based on the detection result of the humidity sensor 6. However, what is measured by the humidity sensor 6 is the relative humidity, that is, the ratio (partial pressure) of the water vapor pressure P to the saturated water vapor pressure P ₀ at the measurement temperature, and the relationship between the relative humidity RH and the water vapor pressure P. Is expressed by the following equation (6). In order to obtain the water vapor pressure P using Equation 6, it is necessary to know the saturated water vapor pressure P ₀ .
P = P ₀ × RH ÷ 100 (Formula 6)

On the other hand, the saturated water vapor pressure P ₀ varies depending on the temperature T, and can be calculated from the following Expression 7.

However, since the temperature T is included as a variable in the equation 7, it is necessary to know the temperature T in order to obtain the saturated water vapor pressure P ₀ by the equation 7, and eventually the temperature is required for the temperature measurement. If this is the case, it will be in a state of patronage and the temperature cannot be determined.

  Therefore, in this embodiment, after setting the initial value of the original temperature, the temperature correction process for obtaining the temperature corrected from the original temperature, the propagation time, and the relative humidity is repeated until the measurement target space S is converged. Find the temperature. That is, first, the temperature correction process is performed on the initial value of the original temperature, and from the next time, the temperature correction process is performed using the temperature obtained in the previous temperature correction process as the original temperature until the temperature correction process is converged. Repeatedly, the temperature at convergence is determined as the measured value.

  Here, the initial value of the original temperature is tentatively set and may be greatly different from the true temperature. The temperature correction process is started from the initial value of the original temperature, and the temperature correction process is repeated. It can be close to the true temperature. That is, the corrected temperature obtained by the temperature correction process satisfies the conditions of propagation time and relative humidity, that is, the temperature at which the sound speed is corrected by humidity, approximates the true temperature from the original temperature, By repeating this temperature correction process, it is possible to approach the true temperature.

In particular, in the present embodiment, the temperature correction process is started with the initial calculated temperature (initial value of the original temperature) T ₀ as the temperature obtained from the propagation time assuming dry air, that is, relative humidity 0%. Equation 8 the following is used for the calculation of the initial calculation temperature T _0. This equation 8 is the same as the above equation 3, and does not consider the influence of humidity, that is, obtains the temperature on the assumption that the actually measured sound velocity C ₀ (= L / t) is the sound velocity C in dry air. is there.
T ₀ = (L / t−331.45) /0.607 (Formula 8)

  In this way, the initial value of the original temperature can be set easily, the processing load on the controller 7 can be reduced, and the processing speed can be increased.

In the present embodiment, the saturated water vapor pressure P ₀ is calculated from the original temperature T, the water vapor pressure P is calculated from the saturated water vapor pressure P ₀ and the relative humidity RH measured by the humidity sensor 6, and the water vapor pressure P and A corrected temperature T is calculated from the propagation time t. As a result, the temperature that satisfies the conditions of the propagation time and the relative humidity, that is, the temperature at which the sound velocity is corrected by the humidity can be obtained.

Here, the following equation 9 is used to calculate the saturated water vapor pressure P ₀ from the original temperature T. Equation 9 is substantially the same as Equation 7, but here, the number of repetitions is n, and the temperature T in Equation 7 is the original temperature T _n obtained in the previous (n−1) th temperature correction process. _−1, and the current (n-th) saturated water vapor pressure P _0n is obtained from the previous temperature (original temperature) T _n−1 .

Next, the following equation 10 is used to calculate the water vapor pressure P from the saturated water vapor pressure P ₀ and the relative humidity RH measured by the humidity sensor 6. This equation 10 is the same as the above equation 6, and the current (n-th) water vapor pressure P _n is obtained from the current (n-th) saturated water vapor pressure P _0n .
_Pn = _P0n * RH / 100 (Formula 10)

Next, the following formula 11 is used to calculate the corrected temperature T from the water vapor pressure P and the propagation time t. This equation 11 is the same as the equation 5 described above, and the current (n-th) corrected temperature T _n is obtained from the current (n-th) water vapor pressure P _n and the propagation time t.

  In addition, in this Formula 11, the value of the atmospheric pressure H is required in addition to the water vapor pressure P, but in this embodiment, the atmospheric pressure H is set to a constant value (reference atmospheric pressure). The atmospheric pressure H has a small fluctuation ratio, and even if it is a constant value, the error can be kept small.

When the corrected temperature T _n is obtained in this way, a convergence determination is then made as to whether or not the corrected temperature T _n satisfies a predetermined convergence condition. In particular, here, the absolute value of the difference between the previous temperature (original temperature) T _n-1 and the current corrected temperature T _n is obtained, and converges when it becomes smaller than a predetermined value α (for example, 0.1 ° C.). Judge that it is. In other words, if the following expression 12 is satisfied, it is determined that it has converged.
| T _n −T _n−1 | <α (Formula 12)

  Next, the procedure of the temperature acquisition process performed by the controller 7 will be described. FIG. 3 is a flowchart showing the procedure of the temperature acquisition process performed by the controller 7.

Here, first, initializes the number of repetitions n, i.e. (ST 101) as n = 0, determine the initial calculated temperature _{T 0} by the formula 8 (ST 102).

Next, the number n of repetitions is set to 1 (ST103), and the saturated water vapor pressure P ₀₁ (= P _0n ) is calculated from the initial calculated temperature T ₀ (= T _n−1 ) obtained in ST102 by Equation 9 (ST104). Next, the water vapor pressure P ₁ (= P _n ) is calculated from the saturated water vapor pressure P ₀₁ obtained in ST 104 and the relative humidity RH measured by the humidity sensor 6 using Equation 10 (ST 105). Then, the temperature T ₁ (= T _n ) corrected by Equation 11 is calculated from the water vapor pressure P ₁ obtained in ST 105 (ST 106).

Next, 1 increments the number of repetitions n, that is, as n = n + 1 (ST107) , acquires the temperature _{T n,} which is corrected by repeating the same temperature correction (ST108~ST110) and ST104～ST106. Then, it is determined whether or not it has converged by Expression 12, that is, whether or not the absolute value of the difference between the previous temperature (original temperature) T _n−1 and the current temperature T _n is smaller than a predetermined value α ( ST111). Here, when it is determined that the convergence (Yes in ST111), determines the temperature _{T n} to the final measured temperature (ST 112).

On the other hand, if it is determined that it has not converged (No in ST111), the process returns to ST107, the repeat count n is incremented by 1, and the temperature correction process of ST108 to ST110 is repeated again, and convergence is determined in ST111. . The temperature correction process repeated until convergence, the temperature T _n when it is determined that the convergence determining the final measured temperature (ST 112).

In ST 108, when the number of repetitions n = 2, to calculate a saturated steam pressure _{P 02} the temperatures _{T 1} obtained in ST106 as the previous temperature (original _{temperature) T n-1.} When the number of repetitions n = 3, the saturated water vapor pressure P ₀₃ is calculated from the temperature (original temperature) T ₂ obtained in the previous ST110. Thereafter, the saturated water vapor pressure P _0n is calculated from the temperature (original temperature) T _n−1 obtained in the previous ST110.

(Second Embodiment)
FIG. 4 is an overall configuration diagram showing a temperature measurement device according to the second embodiment. The points not particularly mentioned are the same as in the first embodiment.

  The temperature measuring device 21 includes a temperature sensor 22 and an atmospheric pressure sensor 23 in addition to the humidity sensor 6. In addition to the relative humidity detected by the humidity sensor 6, the temperature or atmospheric pressure sensor detected by the temperature sensor 22. Based on the atmospheric pressure detected at 23, the controller 7 performs a process for obtaining the temperature of the measurement target space. Note that only one of the temperature sensor 22 and the atmospheric pressure sensor 23 may be provided.

  The temperature sensor 22 is installed on the wall surface facing the measurement target space S and detects the temperature near the wall surface. The atmospheric pressure sensor 23 is also installed on the wall surface facing the measurement target space S, but the atmospheric pressure in the vicinity of the wall surface detected by the atmospheric pressure sensor 23 is not significantly different from the average atmospheric pressure of the entire measurement target space S.

The temperature detected by the temperature sensor 22 is used as an initial calculated temperature T ₀ that is an initial value of the original temperature. That is, in ST102 of FIG. 3, instead of the value calculated by the equation 8, the value measured by the temperature sensor 22 is set to the initial calculated temperature T _0. Accordingly, since the temperature correction process can be started at a value close to the actual temperature of the measurement target space S, the number of repetitions until convergence is achieved by repetition of the temperature correction process can be reduced. The load can be reduced and the processing speed can be increased.

In this case, the temperature detected by the temperature sensor 22 can be used as it is as the initial calculated temperature T ₀ , but the value corrected by the relative humidity RH using the graph shown in FIG. 2 is used as the initial calculated temperature. it may be used as T _0. That is, the measurement error is calculated based on the relative humidity RH detected by the humidity sensor 6 and the temperature detected by the temperature sensor 22 by using a mathematical expression or a table representing the relationship shown in the graph shown in FIG. The temperature detected by the temperature sensor 22 is corrected by this measurement error, and the obtained temperature is set as the initial calculated temperature T ₀ .

The atmospheric pressure H detected by the atmospheric pressure sensor 23 is used when correcting the actually measured sound speed to the sound speed in the dry air based on the water vapor pressure. In particular, in the present embodiment, the process for obtaining the sound velocity is omitted, and the temperature T _n is obtained from the water vapor pressure P _n and the propagation time t using Equation 11, and the atmospheric pressure H in Equation 11 is measured by the atmospheric pressure sensor 23. Assign a value. Thereby, the correction of the sound speed due to the humidity is more accurately performed, and the temperature of the measurement target space S can be measured with higher accuracy.

  In the present embodiment, in the temperature correction process, the saturated water vapor pressure, the water vapor pressure, and the corrected temperature are sequentially obtained from the previous temperature, the propagation time, and the relative humidity using Equations 9 to 11. The present invention is not limited to such a procedure.

  For example, although the process of calculating the sound speed is omitted by using Expression 11, the sound speed may be calculated by Expression 4, and Expressions 9 to 11 and other expressions if necessary. It is also possible to create a mathematical expression with reduced variables by modifying and substituting those mathematical expressions, and omit the process of calculating saturated water vapor pressure and water vapor pressure required in the process of obtaining the corrected temperature. . It is also possible to prepare a table corresponding to the above mathematical expression in advance and perform temperature correction processing with reference to this table.

  Furthermore, in the first embodiment and the second embodiment described so far, as shown in FIG. 1 or FIG. 4, the ultrasonic transmitter 2 and the ultrasonic receiver 4 sandwich the measurement target space S. Although they are arranged to face each other and face each other, the present invention is not limited to such a configuration in which they face each other. For example, the structure which has arrange | positioned the ultrasonic transmitter 2 and the ultrasonic receiver 4 facing diagonally is also possible.

  Further, as shown in FIG. 5, the ultrasonic wave transmitter 2 and the ultrasonic wave receiver 4 are arranged side by side in the same direction, that is, facing the other wall surface on one wall surface facing the measurement target space S. You may do it. In such a configuration, the ultrasonic wave transmitted from the ultrasonic wave transmitter 2 once passes through the measurement target space S, is reflected by the wall surface, and passes through the measurement target space S again. 4 is received. In this case, needless to say, the propagation distance L is the sum of the distance from the ultrasonic transmitter 2 to the other wall surface and the distance from the wall surface to the ultrasonic receiver 4. In this way, even in the measurement form using the reflection by the wall surface, it can be said that the ultrasonic transmitter 2 and the ultrasonic receiver 4 are “arranged across the space to be measured” in a broad sense.

  Further, in the present embodiment, the temperature measuring device using ultrasonic waves has been described as an example, but the present invention is not limited to ultrasonic waves, and a configuration using sound waves other than ultrasonic waves such as an audible region, for example. It is also possible to apply to.

  The temperature measurement device and the temperature measurement method according to the present invention can measure the temperature of the measurement target space with high accuracy without being affected by humidity when measuring the temperature of the measurement target space based on the speed of sound. It has an effect and is useful as a temperature measuring device and a temperature measuring method for measuring the temperature of the measurement target space based on the speed of sound.

1, 21 Temperature measuring device 2 Ultrasonic transmitter 4 Ultrasonic receiver 6 Humidity sensor 7 Controller (Temperature acquisition unit)
15 CPU (propagation time acquisition unit)
22 Temperature sensor 23 Barometric pressure sensor

Claims (6)

A temperature measurement device that measures the temperature of a measurement target space based on the speed of sound,
A sound wave transmitter and a sound wave receiver disposed with the measurement object space in between,
A humidity sensor for detecting the relative humidity of the measurement target space;
A propagation time acquisition unit for acquiring a propagation time of a sound wave between the sound wave transmitter and the sound wave receiver;
A temperature acquisition unit for determining the temperature of the measurement target space based on the propagation time acquired by the propagation time acquisition unit and the relative humidity detected by the humidity sensor;
The temperature acquisition unit sets an initial value of the original temperature, and then repeats the temperature correction process for obtaining a temperature corrected from the original temperature, the propagation time, and the relative humidity until the measurement object converges. A temperature measuring device characterized by obtaining a temperature of a space.   In the temperature correction process, the temperature acquisition unit obtains a saturated water vapor pressure from the original temperature, obtains a water vapor pressure from the saturated water vapor pressure and the relative humidity, and calculates a temperature corrected from the water vapor pressure and the propagation time. The temperature measuring device according to claim 1, wherein the temperature measuring device is obtained.   The temperature measuring device according to claim 1, wherein the temperature acquisition unit sets a temperature obtained from the propagation time on the assumption of dry air as an initial value of the original temperature. A temperature sensor for detecting a temperature in the vicinity of the wall surface facing the measurement target space;
The temperature measuring device according to claim 1, wherein the temperature acquisition unit sets the temperature detected by the temperature sensor to the initial value. A pressure sensor for detecting the pressure of the measurement target space;
The temperature measuring device according to any one of claims 1 to 4, wherein the temperature acquisition unit obtains the temperature of the measurement target space based on the atmospheric pressure detected by the atmospheric pressure sensor. A temperature measurement method for measuring the temperature of a measurement target space using sound waves,
A propagation time acquisition step of acquiring a propagation time of a sound wave between a sound wave transmitter and a sound wave receiver disposed across the measurement target space;
A temperature acquisition step of acquiring the temperature of the measurement target space based on the propagation time acquired in this propagation time acquisition step and the relative humidity detected by the humidity sensor, and
This temperature acquisition process
An initial value setting step for setting an initial value of the original temperature;
A temperature correction step for obtaining a corrected temperature from the original temperature and the propagation time and the relative humidity;
A convergence determination step for determining whether or not the temperature obtained in this temperature correction step has converged,
A temperature measuring method characterized in that the temperature correction step is repeated until the temperature in the measurement object space is obtained until it is determined that the convergence has occurred in the convergence determination step.

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