JPH07318397A - Ultrasonic liquid gage - Google Patents

Abstract

PURPOSE:To measure a liquid level independent of temperature change of liquid by calculating ultrasonic wave propagation speed on the basis of a signal from an ultrasonic wave measurer connected to an ultrasonic wave transciever mounted on the bottom wall face of a liquid housing part, finding temperature of the bottom wall, and calculating a liquid level from the temperature and a measured signal. CONSTITUTION:An ultrasonic wave transceiver 3 is mounted on the bottom wall face of piping 1, and an ultrasonic wave measurer 5 is connected thereto. An ultrasonic wave is propagated and transmitted in the bottom wall of the piping 1 and in liquid on the basis of a signal from the transceiver 3, the measurer 5 measured a time t1 up to receiving of an echo wave reflected on a liquid surface 2, and time t2 up to receiving of the cho wave in the bottom wall from transmission of the ultrasonic wave. A liquid level is found from a time interval of the echo wave and an ultrasonic wave propagation speed in the liquid found by the measurer 5, at that time, the propagation speed is calculated by a temperature operation device 8 on the basis of the time t2 and bottom wall thickness, and the bottom wall temperature, namely, temperature of the liquid is found. In response to the temperature signal a correction of the propagation speed in accordance with the time t1 is performed by an operation processor 6 and the liquid level is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level meter for measuring the liquid level of a liquid inside a container (including piping etc.) using ultrasonic waves, and more particularly to a liquid level meter for measuring the liquid temperature range. The present invention relates to an ultrasonic liquid level meter suitable for wide use.

[0002]

2. Description of the Related Art FIG. 7 is a longitudinal sectional view showing an example of a conventional ultrasonic liquid level meter. In this example, the liquid 1 inside a container 110 is
In order to measure the liquid level of the liquid level 114 with respect to 12, the same container 110
An ultrasonic transmitter / receiver (ultrasonic transducer) 120 is mounted on the lower surface of the bottom wall of the. In the ultrasonic transmitter / receiver 120, a vibrator 122 having a silicon film 123 is attached to a base 126 via a cushion part 124, and the vibrator 122 is pressed against the bottom surface of the bottom wall of the container 110.

The ultrasonic transmitter / receiver 12 is used for measuring the liquid level.
Ultrasonic waves are transmitted from 0 toward the liquid surface 114 of the liquid 112 in the container 110. Then, the echo wave 130 reflected on the liquid surface 114 is
It is received by the ultrasonic transmitter / receiver 120. The liquid level can be measured by measuring the time required from transmission to reception. The liquid level thus measured is displayed by an analog display type or digital display type indicating instrument (not shown).

On the other hand, there is a conventional ultrasonic liquid level meter as shown in FIG. 6 (longitudinal sectional view). In this example, when the temperature change range of the liquid passing through the inside of the pipe 1 is wide, The liquid level of the liquid surface 2 is measured in consideration of the temperature. By the way, the temperature of the pipe 1 itself changes due to the temperature change of the liquid inside the pipe 1, and the temperature of the pipe 1 and the temperature of the liquid become the same temperature for a long time. Measurement sensor 11 is pipe 1
It is attached to the outer periphery of.

When the liquid level of the liquid in the pipe 1 is measured using the ultrasonic transmitter / receiver 3 mounted on the lower surface of the bottom wall of the pipe 1, the ultrasonic wave propagation speed changes depending on the temperature of the liquid. Therefore, 1 / the sum of the time when the ultrasonic wave reaches the liquid surface 2 and the time when the ultrasonic wave is reflected from the liquid surface and returns to the ultrasonic wave transmitter / receiver 3.
2 is multiplied by the ultrasonic wave propagation velocity corrected based on the temperature signal from the sensor 11 in the arithmetic processing unit 14 to calculate the correct liquid level.

The display device 7 in FIG. 6 displays the liquid level calculated by the arithmetic processing unit 14, and the ultrasonic liquid level measuring device 12 processes the signal from the ultrasonic wave transmitter / receiver 3 for calculation. The temperature measuring device 13 is for sending to the processing device 14.
Is a processing unit that processes the signal from the temperature measurement sensor 11
It is for sending to 14.

[0007]

By the way, in the conventional ultrasonic liquid level meter as described above, when the temperature of the liquid in the container changes, the temperature measuring sensor 11 shown in FIG. If a large number of liquid level gauge measurement points are provided for each part, the number of temperature measurement sensors required will be enormous, and it will be necessary to consider the mounting space of the sensors. The present invention is intended to solve the above-mentioned problems, and even when the temperature of the liquid in the container changes, the liquid level can be accurately measured without the need for a conventional temperature measurement sensor. It is an object of the present invention to provide an ultrasonic liquid level meter adapted to do so.

[0008]

In order to achieve the above-mentioned object, an ultrasonic liquid level meter of the present invention is mounted on the lower surface of the bottom wall of a liquid containing portion in order to measure the liquid level of the liquid in the liquid containing portion. The ultrasonic transmitter / receiver, the ultrasonic measuring device connected to the ultrasonic transmitter / receiver, and the ultrasonic propagation velocity in the bottom wall are calculated based on the signal from the ultrasonic measuring device to calculate the temperature of the bottom wall. And a processor for calculating the liquid level of the liquid based on signals from the ultrasonic measuring device and the temperature calculator.

Further, the ultrasonic liquid level meter of the present invention is designed to measure the liquid level of the liquid in the liquid containing portion and the ultrasonic transmitter / receiver mounted on the lower surface of the bottom wall of the liquid containing portion. Measures the first time from the transmission of the ultrasonic wave propagated from the container to the liquid surface through the bottom wall of the liquid container and the liquid and the reception of the echo wave reflected by the liquid surface of the ultrasonic wave. At the same time, the ultrasonic measuring device measures the second time from the transmission of the ultrasonic wave to the reception of the echo wave in the bottom wall, and the second time after receiving the signal from the ultrasonic measuring device. Based on the temperature calculator that calculates the propagation velocity of the ultrasonic wave in the bottom wall based on the temperature to obtain the temperature of the bottom wall, and in the liquid obtained by receiving the temperature signal from the temperature calculator and corresponding to the temperature signal Ultrasonic velocity at the It is characterized in that the configured time and an arithmetic processing unit for calculating a liquid level of the liquid based on the difference between the second time.

[0010]

In the ultrasonic liquid level meter of the present invention described above, based on the detection signal from the ultrasonic transmitter / receiver, an ultrasonic wave is used to detect the ultrasonic wave in the liquid in the container and the ultrasonic wave in the bottom wall of the container. The time interval for the echo wave of the sound wave propagation is determined.

Then, the liquid level is obtained from the time interval of the echo waves of the ultrasonic waves in the liquid obtained by the ultrasonic measuring device and the ultrasonic wave propagation velocity in the liquid. Based on the time interval for the echo wave of the ultrasonic wave propagation in the bottom wall of the liquid containing portion obtained and the known bottom wall thickness, the temperature of the bottom wall and thus the temperature of the liquid is obtained by the temperature calculator, and by the temperature signal Since the ultrasonic wave propagation velocity in the liquid is corrected by the arithmetic processing unit, the liquid level can be accurately calculated.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An ultrasonic level gauge as an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view schematically showing the arrangement of the ultrasonic level gauge, and FIG. Explanatory diagram schematically showing multiple echoes at the time of transmission, FIG.
Is an explanatory view schematically showing multiple echoes when ultrasonic waves are received by the ultrasonic transmitter / receiver, FIG. 4 is a graph showing echo levels of echo waves received by the ultrasonic transmitter / receiver, and FIG. 5 is ultrasonic wave propagation. It is a temperature characteristic figure of speed.

As shown in FIG. 1, an ultrasonic transmitter / receiver 3 is mounted on the lower surface of the bottom wall of a stainless steel pipe 1 serving as a liquid container, and the ultrasonic transmitter / receiver 3 has an ultrasonic measuring device 5 attached thereto. Are connected. Then, in the ultrasonic measuring device 5, based on the signal from the ultrasonic transmitter / receiver 3, from the transmission of the ultrasonic wave propagated toward the liquid surface 2 through the bottom wall of the pipe 1 and the liquid, the liquid of the ultrasonic wave is transmitted. The function of measuring the first time t ₁ until the reception of the echo wave reflected on the surface 2 and the second time t ₂ from the transmission of the ultrasonic wave to the reception of the echo wave in the bottom wall is performed. It is supposed to be done.

That is, when the ultrasonic transmitter / receiver 3 transmits, multiple echoes occur in the bottom wall of the pipe as shown in FIG. 2, and when the ultrasonic transmitter / receiver 3 receives the multiple echoes as shown in FIG. Then, the time measuring action for these echoes is performed by the ultrasonic measuring device 5 as shown in FIG. 4, and the above-mentioned first time t ₁ and second time t ₂ are obtained.

Further, in the temperature calculator 8 connected to the ultrasonic measuring device 5, the ultrasonic wave propagation velocity v _{1 on the} bottom wall is calculated by the following equation from the second time t ₂ and the known bottom wall thickness d. [Equation 1]
Required by.

V ₁ = 2d / t ₂ Therefore, the temperature T _{1 of the} bottom wall is obtained by the temperature calculator 8 based on the temperature characteristic diagram shown in FIG. Since this temperature T ₁ is estimated as the temperature of the liquid, the ultrasonic wave propagation velocity v ₀₁ in the liquid is obtained from the temperature characteristic diagram of the sound velocity in the liquid.
Is calculated, and the calculation is performed in the arithmetic processing unit 6 connected to the temperature calculator 8.

In this way, in the arithmetic processing unit 6, the first time t ₁ and the second time t ₂ from the ultrasonic measuring device 5 are obtained.
And the ultrasonic propagation velocity v ₀₁ described above, the liquid level L can be obtained from the following relational expression [Equation 2].

2 L = v ₀₁ × (t ₁ −t ₂ ) The liquid level L thus obtained is displayed on the display device 7 connected to the arithmetic processing device 6.

As shown in FIG. 5, when the temperature changes from T ₁ to T ₂ , the propagation velocity of the ultrasonic wave in the bottom wall of the pipe 1 also changes from v ₁ to v ₂ , so that the ultrasonic wave The multiple echo measured by the measuring instrument 5 also changes as shown by the broken line in FIG. Also in this case, the liquid level L is calculated by the following relational expression [Equation 3].
Is obtained in the same manner as described above.

## EQU3 ## 2L = v ₀₂ × (t ₁ ′ −t ₂ ′)

[0018]

As described in detail above, according to the ultrasonic liquid level meter of the present invention, the following effects can be obtained. (1) Even when the temperature of the liquid in the liquid storage part such as the pipe or container changes significantly, the temperature measurement sensor such as the thermistor that measures the temperature can be omitted, and the liquid level can be measured with high accuracy. be able to. (2) Since the temperature measuring sensor is not needed, the installation space of the ultrasonic liquid level gauge on the pipe etc. can be reduced. (3) Since the signal processing circuit does not require a temperature measuring sensor, it can be unified into a processing circuit for ultrasonic waves, and the configuration of the processing circuit can be greatly simplified.

[Brief description of drawings]

FIG. 1 is an explanatory diagram schematically showing an arrangement configuration of an ultrasonic liquid level gauge as one embodiment of the present invention.

FIG. 2 is an explanatory diagram schematically showing multiple echoes at the time of transmitting ultrasonic waves from an ultrasonic transceiver in the ultrasonic liquid level meter of FIG.

FIG. 3 is an explanatory diagram schematically showing multiple echoes when ultrasonic waves are received by an ultrasonic wave transceiver in the ultrasonic liquid level meter of FIG.

FIG. 4 is a graph showing echo levels of echo waves received by the ultrasonic transceiver.

FIG. 5 is a temperature characteristic diagram of ultrasonic wave propagation velocity in a vessel wall and in a liquid.

FIG. 6 is a schematic view showing an example of a conventional ultrasonic liquid level meter.

FIG. 7 is a schematic diagram showing another example of a conventional ultrasonic liquid level meter.

[Explanation of Codes] 1 Piping as a Liquid Storage Section 2 Liquid Level 3 Ultrasonic Transceiver 4 Ultrasonic Wave Propagating in Liquid 5 Ultrasonic Measuring Device 6 Calculation Processing Device 7 Display Device 8 Temperature Calculation Device

Claims (2)

[Claims] 1. An ultrasonic transmitter / receiver mounted on a lower surface of a bottom wall of the liquid containing portion for measuring a liquid level of the liquid containing portion, and an ultrasonic measuring device connected to the ultrasonic transmitter / receiver. , A signal from the ultrasonic measuring device and the temperature calculating device, which calculates the ultrasonic propagation velocity in the bottom wall based on the signal from the ultrasonic measuring device to obtain the temperature of the bottom wall An ultrasonic liquid level meter, comprising: an arithmetic processing unit that calculates the liquid level of the liquid based on the above. 2. An ultrasonic transmitter / receiver mounted on a lower surface of a bottom wall of the liquid containing portion for measuring the liquid level of the liquid in the liquid containing portion, and the ultrasonic transmitter / receiver in the bottom wall of the liquid containing portion. And measuring the first time from the transmission of the ultrasonic wave propagated toward the liquid surface via the liquid to the reception of the echo wave reflected by the liquid surface of the ultrasonic wave, and from the transmission of the ultrasonic wave to the above. An ultrasonic measuring device for measuring a second time until the reception of the echo wave in the bottom wall, and a propagation velocity of the ultrasonic wave in the bottom wall based on the second time when receiving a signal from the ultrasonic measuring device. And a temperature calculator for calculating the temperature of the bottom wall, and an ultrasonic wave propagation velocity in the liquid obtained by receiving a temperature signal from the temperature calculator and corresponding to the temperature signal, Difference between the first time and the second time received from the sound wave measuring device An ultrasonic liquid level meter, comprising: an arithmetic processing unit that calculates the liquid level of the liquid based on the above.