JPS63311134A - Temperature measuring apparatus - Google Patents

Abstract

PURPOSE:To make it possible to measure temperature regardless of the distance between wave transmitting and receiving devices, by transmitting ultrasonic waves having at least two kinds of frequencies in a gas to be measured in a pulse shape, obtaining the ratio between propagating times, and obtaining the temperature based on relationship between the temperature and a propagating speed, which is obtained beforehand. CONSTITUTION:An ultrasonic wave having a first frequency f1 is sent from a first wave transmitter 16 in a pulse shape aided by gate generating circuits 11 and 12. The wave is received with a first wave receiver 17. An ultrasonic wave having a second frequency f2 is sent from a second wave transmitter 26 in a pulse shape and received with a second wave receiver 27. The time from the transmitter 16 to the receiver 17 and the time from the transmitter 26 to the receiver 27 are obtained with frequency counters 20 and 30. The temperature data of a gas which is present between both wave transmitters 16 and 26 and both receivers 17 and 27 are obtained on the basis of the ratio between both times. The distance data between the transmitters and the receivers can be obtained from the results. An oscillating device 1 comprises an oscillator 1, a frequency synthesizer 3, a frequency divider 4 and the like. The oscillator 2 is, e.g., an original oscillator such as a crystal oscillator. The oscillator 2 oscillates a reference frequency signal and applies the signal to the frequency synthesizer 3.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a temperature measuring device using ultrasonic waves.

[Conventional technology]

Devices that measure the temperature of gas using ultrasonic waves are known. For example, a common method is to measure the temperature of a gas, which is the propagation medium of the ultrasonic pulse, by detecting the propagation velocity of the ultrasonic pulse over a predetermined distance.

Specifically, the velocity V of a sound wave propagating in a gas has the relationship v = (yρ) where the density of the gas is ρ9 and the bulk modulus is y. It will be destroyed.

v=(γRT/M)l/2...filR However, T: specific heat ratio of gas (specific heat at constant pressure/specific heat at constant volume) R: gas constant M: molecular weight T: temperature Therefore, if the speed of sound ■ is known, the temperature T can be found.

Note that the sound velocity V is determined by the following equation (3).

v = It / t ... (3) However, l: distance between the transducer and t: time required for the sound wave to reach the distance l. Furthermore, as a method to more accurately measure the sound speed V, it is possible to This method measures the propagation time of an ultrasonic pulse by repeating the process of transmitting the next ultrasonic pulse at the same time it is received and counting the number of pulses that can be transmitted within a predetermined time.
The around method and the like are also widely used in practice.

FIG. 3 is a block diagram showing the configuration of an apparatus for implementing the above sing-around method.

Specifically, an ultrasonic pulse generated by an ultrasonic pulse oscillator 51 is transmitted from a transmitter 52 into the gas to be measured, and is received by a receiver 53 separated by a predetermined distance. The waveform amplified by the amplifier 54 and detected by the detector 55 is shaped by the waveform shaping circuit 56, and then given to the ultrasonic pulse oscillator 51 again to perform the same processing as described above. on the other hand,
The waveform detected by the detector 55 is also provided to a frequency counter 57, which counts the number of ultrasonic pulses received.

In such a device, each time the ultrasonic pulse transmitted from the transmitter 52 is received by the receiver 53, a new ultrasonic pulse is transmitted from the transmitter 52, but this cycle is It is proportional to the speed at which the acoustic pulse propagates between the transmitter 52 and the receiver 53.

Therefore, the frequency counter 5 during a certain period of time
The count value of 7 is a function of the propagation speed between the ultrasonic wave transmitter 52 and the wave receiver 53. Therefore, since the speed of the ultrasonic wave can be determined, the temperature of the gas to be measured, which is the propagation medium, can also be determined.

[Problem that the invention seeks to solve]

However, with the conventional ultrasonic temperature measuring device as mentioned above,
The distance between the transducer and receiver must be constant and known. In other words, it is difficult to accurately measure temperature when the distance between the transducer and the transducer is unknown or changing, specifically when the transducer is moving relative to the transducer. It is.

The present invention was made in view of these circumstances, and
It is an object of the present invention to provide a temperature measuring device capable of accurately measuring the temperature of gas interposed between a transducer and a receiver even when the distance between the transducer and receiver is unknown or changing.

[Means for solving problems]

In the temperature measurement device of the present invention, ultrasonic waves of at least two different frequencies are transmitted in pulses into the gas to be measured, and the ratio of their propagation times is determined, and the temperature and the difference are determined in advance. The configuration is such that the temperature is determined from the relationship between the frequency and the propagation velocity of ultrasonic waves.

The temperature measuring device of the present invention includes: an oscillation device that generates a plurality of signals of different frequencies; a first pulse modulator that outputs a signal of a first frequency generated by the oscillation device in a pulsed manner; a first transmitter that converts a signal of the first frequency generated in a pulsed manner from a first pulse modulator into an ultrasonic wave and transmits the wave into the gas to be measured; a second pulse modulator that outputs a signal of a second frequency in a pulsed manner; and a measurement target by ultrasonically converting the signal of the second frequency generated in a pulsed manner from the second pulse modulator. a second wave transmitter that transmits waves into the gas; a first wave receiver that receives the ultrasonic waves transmitted from the first oscillator;
a first device that counts the number of times the ultrasonic wave is received by the first receiver;
a second receiver that receives the ultrasound transmitted from the second oscillator; and a second counter that counts the number of times the ultrasound is received by the second receiver. , a means for causing each of the two transmitters to transmit an ultrasonic wave each time each of the two receivers receives an ultrasonic wave, a ratio of the counts per unit time of the two counters, and a temperature of the gas to be measured. and a means for determining the temperature of the gas to be measured from the ratio of the counts per unit time of the two counters and the contents stored in the storage means. It is characterized by

(Function) In the temperature measuring device of the present invention, ultrasonic waves of two different frequencies are transmitted in pulses through the gas to be measured, and the temperature of the gas to be measured is determined based on information on the ratio of their propagation velocities. Therefore, temperature measurement can be performed regardless of the distance between the ultrasonic transmitter and receiver.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof.

FIG. 1 is a block diagram showing the configuration of a temperature measuring device according to the present invention. Briefly, the device of the present invention transmits ultrasonic waves of the first frequency f1 in pulses from the first transmitter 16, and it takes until the pulses are received by the first receiver 17. time, and the ultrasonic wave of the second frequency f2 is sent to the second transmitter 26.
This pulse is sent to the second receiver 27 in the form of a pulse.
The time required for the wave to be received by the transmitter 16, 26 and the receiver 17, 27 is determined from the ratio of the two, and furthermore, From this result, it is also possible to obtain distance information between the transducers.

1 in the figure is an oscillation device, oscillator 29 frequency synthesizer 39
It consists of a frequency dividing circuit 4 and the like. The oscillator 2 is an original oscillator such as a crystal oscillator, and oscillates a reference frequency signal having a frequency fo to provide it to the frequency synthesizer 3.

The frequency synthesizer 3 uses the reference frequency f given from the oscillator 2.
For example, signals of various frequencies are generated by multiplying the signal of f, and in this embodiment, the signal of the first frequency f is sent to the mixer 14 via the amplifier 13,
The signal of the third frequency f3 is supplied to the mixer 24 via the amplifier 23, and the signal of the third frequency f3 is supplied to the frequency dividing circuit 4.

The frequency divider circuit 4 divides the third frequency signal f3 given from the frequency synthesizer 3 and supplies necessary analog clock signals to each of the first gate generation circuit 11 and the second gate generation circuit 12. .

Both gate generation circuits 11, 12 provide their respective generated gate signals to mixers 14 and 24.

From the remixer 14.24, therefore, the amplifier 13.23
First and second frequency signals f1. as continuous waves given from f1. f2 is output in a pulsed manner only for the period of the gate signal given from the gate generation circuit 11.12, that is, it is pulse-modulated, and the pulse is given to the first and second transmitters 16 and 26 via the amplifier 15.25, respectively. Functions as a modulator.

Both transmitters 16 and 26 convert the respective applied signals into ultrasonic waves and transmit the waves into the gas to be measured.

The first and second receivers 17.27 are the first and second receivers described above.
The ultrasonic waves transmitted from the transmitters 16 and 26 are received, converted into electrical signals, and applied to the detectors 19 and 29 via amplifiers 18 and 28, respectively.

Both detectors 19.29 detect the signals given from the amplifiers 18.28, respectively, and output the signals to the first and second detectors. to the second frequency counter 20.30.

Both frequency counters 20.30 count the number of pulses included in the given signal within a certain period of time, and provide the results and information on the timing of the pulse outputs of both detectors 19.29 to the microcomputer 40.

The microcomputer 40 includes both frequency counters 20,
The pulse width, pulse repetition frequency, and conversion timing of pulse modulation in the remixer 14 24 are determined in accordance with the information provided from the remixer 14 , and a control signal therefor is provided to the aforementioned gate generation circuit 11 , 12 .

Reference numeral 41 in the figure is a memory table in which, as will be described later, the relationship between the ratio of the count values of both frequency counters 20 and 30 and the temperature of the gas is determined in advance and stored.

Now, the microcomputer 4o calculates the ratio of the counted values of both frequency counters 20.30, reads out the value corresponding to this from the stored contents of the memory table 41,
．． The distance between 26 and both receivers 17 and 27 is calculated, and the calculation method will be explained below.

The temperature of the gas interposed between the transducer and the transducer at a certain time is T
, when the distance between the transducer and the transducer is 11, the frequencies f1 and f
The speeds v1 and v2 of the sound waves in No. 2 are expressed by the following equations (4) and (5).
It is expressed by the formula.

v 1-1 + / tI ... (4) ■2=4
'+/12...(5) However, t: frequency f1
Time required for a sound wave of frequency 12 to arrive between the transducer and the transducer tl: Time required for a sound wave of frequency 12 to arrive between the transducer and the transducer Here, if the counting time of the input pulse by both frequency counters 20 and 30 is τ, then the following ( Equations (6) and (7) are obtained.

τ=nXt1...(6) τ"' m X t2...(7) However, n:
The following equation (8) is obtained from equations (4)2 to (7), where m is the number of received pulses of the sound wave with frequency f1: the number of received pulses of the sound wave with frequency f2.

t2 /11=v2 /v1=n/m (8) That is, the ratio n/m of the number of received pulses at two types of frequencies f1 and f2 by each of the frequency counters 20.30 and the retransmitter 16 If the relationship between .26 and the distance l between both receivers 17 and 27 is determined in advance and stored in the memory table 41 in the form of a table (or in the form of an approximation formula), it is possible to The distance l is determined from the ratio n/m of the count values of the frequency counter 20.30 obtained.

Furthermore, from equations (6) and (7), the following equations (81 and (91) show that the sound waves of the respective frequencies f, , f2 are transmitted to both transmitters 1
Since the time tl+t2 required for the wave to reach between the two receivers 17 and 27 from 6°26 can be determined, if the temperature T is determined as described above, the distance l can also be easily determined.

Using the method described above, the microcomputer 40 determines the temperature T of the gas between both transmitters 16.26 and both receivers 17.27, and further determines the distance l. Further, as described above, the microcomputer 40 outputs trigger pulses to the gate generation circuits 11 and 12 for repeated transmission of sound waves.

tl-τ/n (8) 12=τ/m (9) The operation of the device of the present invention is as follows. This is a timing chart.

The signal of the reference frequency fo oscillated by the oscillator 2 of the oscillator 1 is synthesized by the frequency synthesizer 3 into three types of frequency signals f, , f2° f3, and then sent to the first mixer 14 via the amplifier 13. The signal is then applied to the second mixer 24 via the amplifier 23 and to the frequency dividing circuit 4, respectively.

The frequency dividing circuit 4 generates a clock signal based on the given frequency f3 and supplies it to the gate generating circuits 11 and 12. Then, when the gate generation circuits 11 and 12 receive a trigger pulse from the microcomputer 40 based on the applied clock signal, as shown in FIG. 2(a) and (dl),
A gate signal is generated and applied to the premixer 14.24.

As a result, continuous wave signals of frequency f1 and f2 are output from the premixers 14 and 24 to both gate generation circuits 11 and 11, respectively.
Only the part corresponding to the gate width of the gate signal given from 12 is pulsed as shown in Fig. 2 To) and te+,
The signal is output, converted into an ultrasonic wave by a wave transmitter 16.26, and transmitted into the gas to be measured.

The ultrasonic wave transmitted into the gas is transmitted to both receivers 17 and 27.
Fig. 2 fc), (received as a waveform as shown in 0,
After being detected by the wave detector 19.29, the number of input pulses is counted by both frequency counters 20.30.

The microcomputer 40 also controls the image frequency counter 2.
When counting by 0.30 is performed, in other words, when the ultrasonic pulses transmitted from both transmitters 16.26 are received by both receivers 17.27, gate generation circuit 11 or A trigger pulse is applied to 12 to transmit the next ultrasonic pulse. In this way, the transmission of ultrasonic pulses is repeated sequentially, and the frequency counter 20 .
By determining the count values n and m of 30, the microcomputer 40 determines the temperature T and the distance β.

〔Effect of the invention〕

As described above, according to the device of the present invention, it is possible to measure the temperature even when the distance between the transducers is unknown or is changing, and it is possible to measure the temperature between the transducers and the transducers based on the measured temperature. It is also possible to measure the distance between

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the temperature measuring device according to the present invention, Fig. 2 is a timing chart for explaining the operation of the device of the present invention, and Fig. 3 is temperature measurement using the conventional general sing-around method. FIG. 2 is a block diagram showing the configuration of the device. 1... Oscillation device 14.24... Mixer 16.2
6... - Transmitter 17.27... Receiver 20.30
...Frequency counter 40...Microcomputer 41...Memory table

Claims (1)

[Claims] 1. An oscillation device that generates a plurality of signals of different frequencies; a first pulse modulator that outputs a signal of a first frequency generated by the oscillation device in a pulsed manner; a first transmitter that converts the first frequency signal generated in a pulsed manner from the first pulse modulator into an ultrasonic wave and transmits the signal into the gas to be measured; a second pulse modulator that outputs a signal of a second frequency in a pulsed manner; a second wave transmitter that transmits waves into the gas; a first wave receiver that receives the ultrasonic waves transmitted from the first oscillator; and a first wave receiver that receives the ultrasonic waves transmitted from the first oscillator; a first counter that counts the number of times the ultrasound is received; a second receiver that receives the ultrasound transmitted from the second oscillator; and a number of times the ultrasound is received by the second receiver. a second counter for counting the count value per unit time of the two counters; a storage means in which the relationship between the ratio and the temperature of the gas to be measured is determined and stored in advance, and the temperature of the gas to be measured is determined from the ratio of the counts per unit time of the two counters and the contents stored in the storage means. A temperature measuring device characterized by comprising: means for determining .