JP3224295B2 - Temperature measurement device using ultrasonic waves - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature measuring device for measuring the temperature in an area by using ultrasonic waves, and more particularly, to accurately measuring the temperature of each part in the area or the average temperature in the area with a small ultrasonic element. The present invention relates to a temperature measuring device capable of measuring the temperature. The device can be used for various devices related to temperature monitoring and temperature control, for example, zone air conditioning of an air conditioner mounted on a vehicle.

[0002]

2. Description of the Related Art Conventionally, there has been known a temperature measuring device using ultrasonic waves. For example, JP-A-2-171809
Japanese Patent Application Laid-Open Publication No. H11-15764 discloses an apparatus in which an ultrasonic beam is divided into two, and one is used for temperature measurement in a room and the other is used for temperature control or on / off control of an air conditioner or the like. This device is
When receiving ultrasonic waves reflected on the hand near the device, for example, it performs on / off control of the device, and when receiving ultrasonic waves reflected on the wall distant from the device, measures the temperature in the room from the propagation time. Is going. In addition, Japanese Utility Model Laid-Open No. 1-107942
The publication discloses a device in which a plurality of ultrasonic distance meters are provided on one wall of a room, and an average temperature in the room is measured from output signals of the respective distance meters.

[0003]

However, when measuring the temperature of each part in a room or the average temperature in a region, for example, the former device uses the temperature on one propagation path of the ultrasonic wave to measure the average temperature in the region. Therefore, a temperature difference from the actual average temperature is caused. Also, the latter device is
It is necessary to provide a plurality of measuring devices in accordance with the position to be measured in the area, which naturally increases the cost.

[0004] Further, when measuring the propagation time of the ultrasonic wave in the temperature measurement process, both of them measure the time from when the ultrasonic wave is transmitted to when the ultrasonic wave is received. Contains an error. That is, when receiving the ultrasonic wave, the reception level of the ultrasonic wave fluctuates, so that it is not possible to accurately detect the reception time point, and an error due to this eventually lowers the accuracy of the temperature measurement value.

[0005] Therefore, the present invention can measure the temperature at a plurality of points in a region with a small number of ultrasonic elements, and can measure the temperature of each part accurately without being affected by the fluctuation of the ultrasonic wave reception level. It is intended to provide a measuring device.

[0006]

According to the present invention, an embodiment shown in FIG. 1 is employed to solve the above-mentioned problems. The present invention relates to a temperature measuring device for measuring the temperature of each part in a medium using an ultrasonic element provided in a medium, wherein the ultrasonic wave is transmitted from the ultrasonic element into the medium and received by the same or different ultrasonic element. Timing determining means 1 for determining a transmission timing for transmitting an ultrasonic wave and a reception timing for receiving based on each propagation distance of each ultrasonic wave to be transmitted, and an ultrasonic wave received by the ultrasonic element Selection detecting means 2 for selectively detecting the ultrasonic wave based on the reception timing, a wave number that is a multiple of the period of the ultrasonic wave when calculating the propagation time between the transmission and reception of the detected ultrasonic wave, A propagation time calculating means 3 for calculating using the phase difference between the transmitted and received ultrasonic waves and a temperature converting means 4 for converting the propagation time into a temperature are provided. At this time, the ultrasonic element
The same ultrasonic element may be used for both transmission and reception of ultrasonic waves. The propagation time calculating means 3 calculates the change amount between the currently calculated wave number and the previously calculated wave number, and the change amount between the currently detected phase difference and the previously detected phase difference when calculating the ultrasonic wave propagation time. It is preferable to further provide a means for calculating the amount and calculating a correction value for the current wave number from each of these amounts of change.

[0007]

According to the above embodiment, after the ultrasonic wave is transmitted at the transmission timing determined by the timing determining means,
Ultrasonic waves are selectively detected by the selection detecting means 2 at the reception timing determined by the timing determining means 1. Thereby, since each ultrasonic wave propagating through a different propagation path in the medium is individually detected, each ultrasonic wave can be received by a small number of ultrasonic elements, and each received ultrasonic wave can be received. The propagation time can be calculated for each sound wave.

The propagation time of each ultrasonic wave related to the temperature measurement is calculated by the propagation time calculating means 3 based on the period of the transmitted ultrasonic wave. In the present invention, the propagation time of an ultrasonic wave is a rough time value in units of a cycle, for example, a wave number obtained by expressing a delay time between transmission / reception of an ultrasonic wave by an integral multiple of one cycle of the ultrasonic wave and the ultrasonic wave. A set of an approximate value represented by a product of the period and a detailed time value obtained by converting the period into time, for example, a detailed value representing the phase change amount of the ultrasonic wave in the above-described delay time in a range of one period of the ultrasonic wave. It is calculated by the combination. The wave number used for calculating the approximate value is, for example, one unit of the ultrasonic wave, so that it is hardly affected even if the reception level of the ultrasonic wave fluctuates. The phase difference is always a phase change because the phase of the ultrasonic wave is not affected by the fluctuation even if the reception level of the ultrasonic wave fluctuates.
By calculating the propagation time by combining the wave number and the phase difference in this manner, it is possible to calculate an accurate propagation time without strictly measuring the reception point of the ultrasonic wave, and based on this propagation time. For example, the temperature of each part in the medium can be measured using a known relational expression.

In the calculation of the propagation time, as long as the ultrasonic wave can be stably propagated, even if the propagation distance is set long, the wave number for calculating the propagation time only increases, and the detailed value is calculated. Since the phase difference to be performed always indicates, for example, within the range of one cycle of the ultrasonic wave, the propagation time can be accurately calculated.

Further, when the wave number correcting means is provided, a correction value is generated for the calculated wave number every time the propagation time is calculated. This correction value includes a difference between the currently calculated wave number and the previously calculated wave number, and an element due to a phase change therebetween. For example, when the amount of change in the phase difference during that period exceeds one cycle of the ultrasonic wave, it is added according to the direction of the delay or advance. As a result, an accurate wave number can be obtained even if the reception level greatly changes. Further, this correction value can be adapted to a sudden temperature change in the measured area, an abnormality in the process of calculating the propagation time, or the like by identifying the correction value itself.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. 2 is an overall configuration diagram of one embodiment of a temperature measuring device according to the present invention, FIG. 3 is a time chart of signals in each circuit in the device, FIG. 4 is a time chart showing one temperature measuring example, FIG. FIG. 6 is a flowchart of the temperature measurement operation of the present apparatus.

In FIG. 2, the present temperature measuring device transmits /
An ultrasonic element 10 for both receiving and transmitting, a transmitting unit 20 for transmitting an ultrasonic wave, a receiving unit 30 for generating a receiving signal from the received ultrasonic wave, transmitting and receiving ultrasonic waves and calculating a temperature Microcomputer device 40 that performs signal processing according to
Simply referred to as “MCU”). In the region where the ultrasonic wave propagates (in this embodiment, the medium in the region is “air”), a reflecting plate 51 that reflects the ultrasonic wave is provided.
52 and 53 are provided.

First, the wave transmitting section 20 will be described. Transmitter 20
Is a frequency dividing circuit 21, a transmission gate circuit 22, a driving circuit 23
And The frequency dividing circuit 21 receives the E pulse of the MCU 40 and generates, for example, a 40 KHz reference pulse (reference signal). The transmission gate circuit 22 generates a transmission gate signal synchronized with the reference signal based on the transmission timing signal from the MCU 40. The drive circuit 23 generates a drive signal by ANDing the transmission gate signal and the reference signal,
The ultrasonic element 10 is pulsed to transmit ultrasonic waves.

Each of the reflectors 51, 52, 53 in the medium
Means that the ultrasonic waves have different propagation paths L ₁, L_Two, L_ThreeBe composed
Fixed at appropriate places in the medium so that
You. For the propagation distance in each route, for example, the distance is set in advance
Within the frame being measured or by ordinary surveying equipment
The measured value is input to the MCU 40 in advance. Ma
The angle of the reflecting plate, etc.
It is adjusted in advance with the degree.

Next, the wave receiving section 30 will be described. The wave receiving unit 30 includes an amplification circuit 31, a wave detection circuit 32, a mask circuit 33, a delay time detection circuit 34, and a phase difference detection circuit 35. The ultrasonic wave reflected by each reflector reaches the element 10 with a time difference for each propagation path. Each ultrasound
After being converted into an electric signal by the ultrasonic element 10, the amplification circuit 3
The signal is amplified by 1 and becomes a received signal. Each of the received signals is further input to the received wave detection circuit 32 to be shaped into a received wave detection signal. The received wave detection signal is input to the mask circuit 33,
The selection is detected for each reflector. The mask circuit 33 sets a mask time according to the reception timing set according to the propagation distance of each ultrasonic wave, and prevents the reception of the reception detection signal over the mask time. This mask time is set to a time slightly shorter than the time from the transmission of the ultrasonic wave to the reception of the ultrasonic wave to be detected. The mask circuit 33
After the elapse of the mask time, the received wave detection signal is fetched, and the first received wave detection signal is selected at this time.

The received wave detection signal that has been selectively detected is input to a delay time detection circuit 34 (hereinafter simply referred to as a "time detection circuit") and a phase difference detection circuit 35. Time detection circuit 34
Detects the time when the detection signal rises and estimates the time when the ultrasonic wave is received. Then, the delay time is detected from the time difference between the transmission and reception of the ultrasonic wave. On the other hand, the phase difference detection circuit 35 generates a phase difference signal by pulsing the received signal of the detection signal and comparing the pulse with the reference signal. This phase difference signal is modulated at a sufficiently high frequency, for example, an MCU E pulse, and the pulse is counted.
Each signal of the above-mentioned delay time and phase difference is taken into MCU40.

The MCU 40 calculates the propagation time of the ultrasonic wave from the delay time and the phase difference by a calculation process described later, and calculates the temperature in the medium from the propagation time. The calculated temperature measurement result is output as a signal to the display circuit 61 and digitally displayed, for example, on a 7-segment display. Also, the temperature measurement result can be transferred to other related devices via the transfer circuit 62.

Next, the signals generated by the above circuits will be described with reference to FIG. First, FIG. 3A shows a 40 KHz reference signal generated by the frequency dividing circuit 21, and FIG. 3B shows a transmission gate signal generated by the transmission gate circuit 22. The transmission gate signal is synchronized with the reference signal and is set to an integral multiple of the period of the reference signal. FIG. 3C shows a drive signal output from the transmission gate circuit 22 to the drive circuit 23, and is generated by ANDing the reference signal and the transmission timing signal. The ultrasonic element is driven by this drive signal, and an ultrasonic wave is transmitted.

FIG. 3D shows the received signals A, B, and C which are transmitted by the same ultrasonic element after the transmitted ultrasonic wave is reflected by three reflecting plates, respectively, and amplified by the amplifier circuit. Is shown. For each ultrasonic transmission, each received signal has a time difference according to the propagation distance, and is arranged in the order of the shortest propagation distance. In the case of the present embodiment, since the transmission and reception are performed by the same ultrasonic element, the frequency of the reception signal matches the frequency of the reference signal. Each of the received signals A, B, and C is subjected to threshold processing in a received wave detection circuit, converted into a pulse-like phase signal shown in FIG. 3E, and integrated on the other hand, and received as shown in FIG. It becomes a wave detection signal.

[0020] Hereinafter, FIG. 3 (g) ~ (i) is configured for central reception detection signal B at the respective wave receiving detection signals, i.e., among the reflector, a short propagation distance L ₂ to the second An example of calculating the propagation time of an ultrasonic wave arriving through a reflecting plate that makes a transition will be described. The mask circuit works so as to cut off the output from the mask circuit for a certain period of time from the transmission of the ultrasonic wave in order to detect a desired ultrasonic wave. The mask time is set to a time slightly shorter than the time when the ultrasonic wave arrives, as shown in FIG.

The setting of the mask time, that is, the reception timing will be described. The reception timing is, together with the transmission timing, before measurement, for example, the ultrasonic transmission time,
It is set by the MCU based on the propagation distance, the measurement temperature range, the number of reflectors, and the like. As an example, first, a reflection plate constituting a constant propagation distance is provided in a medium at a constant temperature, and a reception detection signal width when an ultrasonic wave is transmitted for a predetermined time is assumed. The maximum width of the received wave detection signal width is calculated based on this. Thereby, the maximum width of the received wave detection signal per ultrasonic wave is determined. Next, based on the maximum width, an interval between adjacent reception detection signals is appropriately set. An appropriate margin is provided for the setting of this interval, and it is considered that adjacent reception detection signals do not overlap each other. This interval setting simultaneously defines the range of the arrangement size of each reflector.

When the propagation distances are measured by appropriately setting the arrangement of the reflection plate, the reception timing is determined according to each propagation distance, for example, from the transmission of the ultrasonic wave to the reception detection signal of the ultrasonic wave. The time is set shortly before the earliest rise. The transmission timing is determined in consideration of the maximum width and the interval of the reception detection signal and the number of the reflection plates. For example, the frequency of the ultrasonic wave is 40 KHz, the transmission time is 125 μs, and the measurement temperature range is from −50 ° C. to 100 ° C.
° C., the propagation distance is 1.0 m, 2.0 m, respectively, assuming that the minimum value of the difference in the propagation distance by each reflector is 30 cm.
It can be set to 2.3 m.

As described above, the reception timing is given to the mask circuit, and as shown in FIG. 3 (g), the time at which the reception detection signal A is assumed to disappear at the latest, and the detection signal B rises earliest. The mask time is determined between the time assumed and. Thus, the mask circuit selectively detects the detection signal B which rises first after the lapse of the mask time.

After the detection of the detection signal B, the time detection circuit detects the time from the rise of the transmission gate signal to the rise of the detection signal B as a delay time, and detects the delay time signal as M.
Input to the CU (FIG. 3 (h)). FIG. 3 (i) shows a phase difference signal generated by the phase difference detection circuit. After a predetermined pulse elapses from the rise of the detection signal B, the reference is made based on the rise of the reference signal shown in FIG. 3 (a). Thus, it is generated from the phase difference from the phase signal B in FIG. This phase difference signal is then modulated with an E pulse and counted by a counter. The counted phase difference signal (not shown) is further converted into a binary code and input to the MCU.

Next, a process of calculating the propagation time t of the detected ultrasonic wave after one received wave detection signal is detected and the delay time and the phase difference are calculated as described above will be described. The MCU sets this delay time value to, for example, 1
It is converted to a multiple of the period, and the integer part of the value is used as the wave number n for calculating the propagation time. Further, the MCU converts the counted phase difference into a time dp within the range of the one cycle, and uses it for calculating the propagation time. Equation (1) shows a relational expression for calculating the propagation time t. t = (n + α) · T + dp (1) n: wave number α: correction value of wave number T: period of ultrasonic wave (reciprocal of frequency f: 1 / f) dp: conversion value from phase difference It is calculated as an integer by the function int (τ / T), where τ is a delay time.

In the above equation, (n + α) represents the corrected wave value. When the wave number n fluctuates due to a change in the reception level of the ultrasonic wave during the measurement of the propagation time, compensation is made by the wave number correction value α. It was done. When calculating the propagation time, the wave number correction value α is calculated every time the wave number is calculated, and is determined as shown in Table 1 below. And the above (n +
α) · T indicates an approximate value of the propagation time in units of the period of the ultrasonic wave, and dp indicates a detailed value of the propagation time within the same period.

[0027]

A method of calculating the wave number correction value α in Table 1 will be described. [Table 1], among the propagation path L ₁ ~L ₃ shown in FIG. 2 illustrates an example of the ultrasonic waves coming from the second propagation path L ₃ (L = 2). First, in order to calculate the wave number correction value α _2K , the initial values n _20, dp ₂₀ (K = 0) of the wave number and the phase in the ultrasonic wave are determined. The initial value n _20, dp _20, the front of the temperature measurement, transmission and reception ultrasonic waves for detecting delay time is determined by repeating a predetermined number of times. The initial value n ₂₀ of the wave number, among the ultrasound arriving at each propagation path by a series of transmission and reception waves, by calculating the wave number of the predetermined number of times concerning the ultrasound, is determined from the average value. The initial value dp ₂₀ of the phase difference, when the series of transmission and reception wave is repeated, is determined from the phase difference detected at the end of the iteration wave transceiver. That is, the wave number is affected by the reception level.
Is not absent, so to improve the accuracy even a little,
Although the initial value of the wave number is determined by the average value, the phase difference
Is always correct because it is not affected by the reception level in principle.
Value, and therefore always the highest value in subsequent calculations.
The new value is used. Consideration of consistency with subsequent measurements
Considering this, the initial value (the first measurement)
Is the temperature at the end of the initial value measurement, and
The phase difference detected last as the initial value of the phase difference dp ₂₀
Is used. The initial value α ₂₀ of the wave number correction value itself
Is “0”. The calculation method is the same for the initial values n ₁₀ and n ₃₀ and dp ₁₀ and dp ₃₀ of the ultrasonic waves related to the other propagation paths L ₁ and L ₃ . After the calculation of each initial value, the operation of calculating the propagation time according to the main temperature measurement is started. During the calculation of the propagation time, each wave number correction value α _LK is calculated at the same time as the wave number is calculated from the propagation time of each corresponding ultrasonic wave.

The following Table 1 shows the first, second,..., K-th calculation of the propagation time of the ultrasonic wave propagating in L ₂ .
Wave number correction values α _{21 to} α for the calculated wave numbers n _{21 to} n _2k
The method for calculating _2k is shown. For example, the first wave number n ₂₁
Is the wave number correction value α ₂₁ for the initial value n ₂₀ + α ₂₀ and the wave number n
_If the phase difference detected this time has changed by one cycle compared to the initial phase difference dp ₂₀ , an additional value of “+1” or “−1” ([Table 1] (indicated by (± 1)).

When the amount of change in the detected phase difference is, for example, equal to or more than 周期 cycle of the ultrasonic wave at the time of calculating the propagation time, the total phase difference exceeds one cycle of the ultrasonic wave. It may be added assuming that it has increased or decreased by one wave number, or may be added when the cumulative value of the detected amount of change in the phase difference exceeds one cycle of the ultrasonic wave. In other words, when the phase difference changes over one cycle as viewed from the starting point of the reference signal, which is the reference of the phase difference, and the accumulated value of the phase difference passes in the phase delay direction (from 2π side to 0 side), “+1” Is added. On the contrary, when the light beam passes in the leading direction of the phase (from the 0 side to the 2π side), “−1” is added. Note that the additional value is “0” when the light does not pass in any direction. The additional value may be added by determining the accumulated value based on the counted phase difference value detected each time the propagation time is calculated.

The wave number n ₂₁ + alpha ₂₁ after correction Thereby against wave number n _21, it is seen that the n ₂₀ (± 1). This initial value n _20, and corresponds to the additional value is added in accordance with the change in phase is applied to the above equation (1) (n + α) .

Thereafter, the wave number correction value is calculated in the same manner, and the wave number correction value α _2k for the wave number n _2K is, as shown in Table 1, n _{2 (k−1)} + α _{2 (k−1)} −n _2k (± 1). As a result, the wave number of the corrected against wave number _{n 2k (n 2k + α 2k} ) is
In practice, it can be seen that n ₂₀ + Σ (± 1). That is, wave number initial value n ₂₀ of the sum is added the value of the addition value so far.

FIG. 4 shows an example of calculating the propagation time t using the correction value α in this manner. FIG. 4 shows that the frequency of the ultrasonic wave is 4
0 KHz, the temperature of the medium to be measured on the ultrasonic wave is time x ₀
It decreased between x ₃ from shows a state has risen between the time x ₃ in x _6. In FIG. 4, x ₀ to x ₃
Between, the propagation speed of the ultrasonic wave is delayed by a decrease in temperature is gradually increased phase difference dp is (phase lag direction), between the x ₃ of x ₆ in opposite, the medium temperature is increased Since the propagation speed of the ultrasonic wave increases, the ultrasonic wave gradually decreases (phase leading direction). Further, at x ₁ , x ₂ and x ₄ , x ₅ where the phase difference dp corresponds to the period of the ultrasonic wave, an additional value (+1 or −1) is added to the wave number correction value α. The wave number n fluctuates due to the change in the reception level as shown in the figure, but is corrected by the wave number correction value α, and the corrected wave number n + α
Does not show the effects of fluctuations. As a result, the propagation time t
Is the sum of the wave number n + α and the phase difference dp, that is, the wave number n ₀ +
It is represented by the sum of Σ (± 1) and the phase difference dp, and follows the temperature change of the medium.

Thus, the propagation time t is substantially equal to the wave number n
It can be represented by the sum of ₀ + Σ (± 1) and the phase difference dp.
However, if there is a deviation in the initial value n ₀ , the deviation may directly become a measurement error. Therefore, in the present embodiment, the average value α * is determined each time a predetermined number of wave number correction values are calculated, and the deviation of the initial value n ₀ is evaluated. Normally, the wave number correction value α remains at the initial value “0” if the wave number is ideally calculated, but actually increases or decreases due to a change in the reception level. However, when the wave number correction value α is calculated as described above, the average value α * should always change around “0”. Thus, the abnormality can be identified by detecting that the average value α * is biased toward plus or minus. If an abnormality is detected, the initial value of the wave number n ₀ is re-measured and corrected to a new initial value. Further, by evaluating the wave number correction value in this manner, even if the temperature of the medium to be measured temporarily changes extremely rapidly, the initial value can be applied to the change.

Next, a series of operations of the MCU in the temperature measuring apparatus described above will be described with reference to flowcharts shown in FIGS. FIG. 5 shows the wave number correction value α.
₅ shows an operation flowchart for calculating each initial value of _LK . First, initial values n _L0 , dp _L0 of wave number correction values in the first propagation path L ₁ are calculated, and thereafter, each propagation path L ₂ ,. each L _3, shows the course of the initial value of the wave number correction value is calculated. The first step 100 shows the initial setting, in which the entire device is reset at the same time as the power is turned on, and thereafter the measurement temperature range, the ultrasonic frequency,
Basic data such as each propagation distance and the number of reflectors are taken in, and a transmission timing and a reception timing are calculated (Step 1).
10). Next, switch the reception timing corresponding to the first propagation path L ₁ (step 120), and transmitting control ultrasonic above transmission timing (step 130), the delay time and phase difference with respect to wave transceiver according Enter (Step 1
40). Then, the wave number is calculated from the delay time (step 150), and the wave number and the phase difference are stored in a storage device inside the MCU (step 160).

This completes the first calculation on the first propagation path, and then starts the second calculation on the first propagation path. These steps 100 to 140 are:
This is repeated a predetermined number of times (M) (step 170). Then, when a predetermined number of calculations are completed in the first propagation path,
The following calculation is started for the second propagation path L _2, thereafter,
The process is repeated by the number of propagation paths while switching the reception timing (step 180).

After the predetermined number of calculations are completed for each propagation path, the calculated values are averaged to calculate the initial values n _L0 and dp _L0 for calculating the correction value (step 19).
0). In step 200, the initial value α _L0 (= 0) of the wave number correction value itself is set.

Next, referring to FIG. 6, a description will be given of a process of sequentially calculating the propagation times t _{1 to} t ₃ of the respective ultrasonic waves and calculating the temperatures T _{1 to} T ₃ in the medium to be measured after calculating the respective initial values. I do. First, in step 300, the reception timing of the _first propagation path L1 is set, and the transmission of the ultrasonic wave is controlled (step 31).
0). Then enter the delay signal according to the ultrasound, calculates a wave number n ₁₁ from the delay time (step 32
0). Subsequently, a phase difference signal relating to the ultrasonic wave is input to calculate a phase difference (step 330). Based on the steps described above in 340 Table 1 calculates a wave number correction value alpha ₁₁ relating to the ultrasound, and stores the MCU internal storage device. Then, in step 350, the number of calculations β of the wave number correction value α is counted.

In step 360, the number of calculations β is determined, and when the number of calculations reaches the predetermined number X, the average value α ₁ * of the stored wave number correction values α _{11 to} α _1X is calculated (step 360). 370). Then, in step 380,
For example this whether or not the average value alpha ₁ * is within a predetermined range around "0" is determined, when the average value alpha ₁ * is within a predetermined range, the wave number initial value n ₁₀ of that relating to the ultrasonic When it is determined that there is no abnormality, step 390 is executed to calculate the propagation time. Conversely, when the average value α ₁ * is out of the predetermined range, the initial value n _{10 of the} wave number is corrected from step 120. In this case, in step 120,
Only reception timing relating to the ultrasonic waves are set, after only the initial value n ₁₀ of the wave number is calibration, step 300
Is executed.

In step 390, above obtained wavenumber, wavenumber correction value to calculate the propagation time t ₁ according to the ultrasonic accordance with equation (1) from the phase difference, the following relational expression based on the propagation time t ₁ according (2) to calculate the temperature T ₁ (step 400). T = (L / t-331.45) /0.605 (2) T: Temperature (° C.) L: Propagation distance (m) t: Propagation time (sec) Accordingly, the average temperature T in the first propagation path ₁ is calculated, and for example, the measurement result is individually output as a signal to a display or a level meter (step 410). As described above, the temperature measurement operation in the first propagation path is completed. Subsequently, for the temperature measurement operation in the second propagation path, the reception timing of the mask circuit is switched (Step 420), and the process returns to Step 300. Thereafter, similarly, when the temperature measurement operation for the second and third propagation paths is completed, the temperature measurement operation for the first propagation path is performed again. Such a measurement operation is repeated repeatedly until the power switch of the apparatus is turned off.

As described above, for the propagation time of the ultrasonic wave, the wave number and phase difference are accurately calculated for each propagation path, and as a result, the temperature of each part in the medium is accurately measured. For example, when measuring an area of 50 cm (propagation distance / 2 = 50 cm) in the air, for example, the frequency of the ultrasonic wave is set to 40 KHz,
When an experiment was performed with the propagation distance error set to 0.8 mm or less per 50 cm, the accuracy was about ± 5 ° C. when measured using the differentially measured propagation time as in the past. According to the apparatus, it can be measured within about ± 1 ° C.

Although the embodiments according to the present invention have been described above, various modifications and changes can be made to these components. For example, each of the transmitting and receiving ultrasonic elements may be separately provided, or may be disposed to face each other.
Further, the ultrasonic wave transmitted from one ultrasonic element may be received by a plurality of ultrasonic elements. Then, a temperature compensation circuit may be combined with each circuit in the measurement device. Furthermore, the medium to be measured can be adapted regardless of gas, liquid, or solid as long as ultrasonic waves can be propagated. The frequency of the ultrasonic wave that can be used in the present apparatus is not particularly limited, but industrially, it can be applied in appropriate combination with the directivity according to the application, cost, and the like.

[0043]

As described above, according to the present invention, the reception timing is set for each propagation path of the ultrasonic wave, and the ultrasonic wave is shifted while being synchronized with the transmission timing, so that the ultrasonic waves arrive from a plurality of propagation paths. Ultrasonic waves can be received by one ultrasonic element. This eliminates the need to provide a plurality of measuring devices, reduces the cost of the devices, and improves the appearance. In addition, individual values and average values of spatial temperature measurement or temperature change can be intensively monitored at one place, and a fine control signal can be provided to various temperature control devices. Furthermore, in the course of temperature measurement,
By using the wave number and the phase difference based on the period of the ultrasonic wave, the accuracy of the measured value is improved, and the temperature of each part in a wide area in the medium can be measured in a wide temperature range.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a configuration diagram showing one embodiment of a temperature measuring device according to the present invention.

FIG. 3 shows a time chart of each signal generated in each circuit of the present apparatus.

FIG. 4 shows a time chart of a propagation time measurement in the present apparatus.

FIG. 5 is a flowchart illustrating a series of operations performed by an MCU in the apparatus.

FIG. 6 is a flowchart illustrating a series of operations performed by an MCU in the apparatus.

[Explanation of symbols]

 10 Ultrasonic element 40 Microcomputer device (MCU) 51, 52, 53 Reflector

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazutoshi Nishizawa 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) G01K 11/14

Claims (3)

(57) [Claims] 1. A temperature measuring device for measuring the temperature of each part in a medium using an ultrasonic element provided in a medium, wherein the wave is transmitted from the ultrasonic element and received by the same or different ultrasonic element. Means (1) for determining a transmission timing for transmitting the ultrasonic wave and a reception timing for receiving the ultrasonic wave based on each propagation distance of each ultrasonic wave to be transmitted, and an ultrasonic wave received by the ultrasonic element. Means (2) for selectively detecting based on the reception timing, and calculating a propagation time between transmission / reception of the detected ultrasonic wave, a wave number which is a multiple of the period of the ultrasonic wave, and Temperature measurement, comprising: a propagation time calculating means (3) for calculating using a phase difference between transmission and reception of ultrasonic waves; and means (4) for converting the propagation time to temperature. apparatus. 2. The ultrasonic element according to claim 1, wherein the ultrasonic element transmits and receives an ultrasonic wave.
An apparatus according to claim 1. 3. The propagation time calculating means (3) calculates the amount of change between the currently calculated wave number and the previously calculated wave number, and the currently detected phase difference and the previously detected phase difference when calculating the ultrasonic wave propagation time. The apparatus according to claim 1, further comprising a unit configured to calculate a change amount from a phase difference and calculate a correction value for the current wave number from each of the change amounts.