SU373539A1 - ULTRASONIC DOORSTER - Google Patents

Description

The invention relates to a measurement technique, in particular, to ultrasonic devices for measuring the level of a liquid, and can find application in the chemical, food, shipbuilding industry, as well as in those areas of technology where the need arises to measure and control the level of liquid products, including aggressive liquids at high pressure, as well as in pitching conditions.

Known waveguide level gauges provide level measurement in limited ranges, due to the ambiguity of the phase meter readings as the active length of the sensor waveguide increases.

The described level gauge differs from the actual ones in that it is equipped with additional emitting and receiving transducers connected by its ribbon waveguide, a measuring circuit connected to the receiving transducer and controlled by a delay and shaping unit, and a phase meter with an indicator whose inputs are connected to the main outputs and additional measuring circuits, while the thickness of the main waveguide is larger than the additional thickness by an amount that ensures the difference in phase shifts at the receiving end of the waveguide in no more than 2 liters when filling and emptying the sensors, and the second input of the main phase meter is connected to the output of the additional measuring circuit. This allows you to expand the measurement range. The drawing shows the block diagram of the described level gauge.

It contains a generator / clock pulse of the chroniser, a generator of modulating voltage 2, a key stage 3, and a generator of 4 continuous oscillations of ultrasonic frequency connected to one of the inputs of the key stage 3. From the output of the key stage, simultaneously playing a role and power amplifier, the signal is fed to the radiating converters 5 of the sensor of the main and additional channels. The transducers are connected to two belt waveguides 6 and 7 of different thickness, with the waveguide 6 of the main channel having a greater thickness, and the waveguide 7 of the secondary channel with a smaller thickness. At the opposite ends of the waveguides there are iriem transducers S and 5, connected respectively to two channels (additional and main) of the measuring circuit. The additional channel of the measuring circuit contains the amplifier 10 and the key stage //, which is controlled from the delay and shaping unit 12; The main channel contains an amplifier J3 and a key stage 14. To the outputs of key stages 11 and 14, connect a phase meter / 5 with an indicator 16. For

Providing measurement with extremely high accuracy, another phase meter 17 with an indicator device 18 at the output is connected between the key stage 11 and the generator 4.

The gauge works as follows. The clock generator / produces a sequence of short pulses following with a period ensuring that there is no reverberation noise in the sensor, and a pulse duration shorter than the double travel time by the pulse from the radiator to the receiver. These pulses are applied to a generator of modulating voltage 2, which produces a bell-shaped pulse. With these pulses, a key stage 3 opens, at the output of which a high-frequency pulse is formed with a bell-shaped envelope. This pulse is applied to electromechanical radiating transducers 5 of the main and additional channels, which excite bending waves in waveguides. Due to the fact that the thickness of the waveguides is different, the phase delay is also different, and at the attachment point of the receiving transducers 5 and 9, the received signals differ in phase by the value of F1 with the sensor not immersed. When the liquid level changes, the phase velocity in the waveguides varies to different degrees, since the waveguide thickness varies, and when the sensor is fully loaded with a liquid, the phase shift between the received signals is (p2.

The thickness of the waveguides is chosen such that the difference cp2-f1 is not more than 2 liters.

At the output of amplifiers 10 and 13, key stages 11 and 14 are included to gate the middle part of the received signal free from dispersion distortion. The delay and shaping unit 12 provides signals to key stages 11 v (. 14 of the required duration, which is about half the duration of the probe pulse and delayed relative to the probe pulse for the run time from the transmitter to the receiving transducer.

In an instrument with a precise scale in another embodiment, the phase meter 17 can be powered from the generator 4 continuous oscillations and from the key stage of the additional channel.

Subject invention

Ultrasonic level gauge containing radiating and receiving transducers interconnected by a tape waveguide, clock generator, modulating voltage generator, a key stage connected to the radiating transducer

and a continuous vibration ultrasonic generator, the second input of which is connected to a phase meter of a measuring circuit controlled by a delay and shaping unit, characterized in that, in order to extend the measurement range, it is equipped with additional radiating and receiving converters connected by its ribbon waveguide, measuring circuit, connected to the receiving transducer and controlled by a delay and shaping unit, and a phase meter with an indicator, the inputs of which are connected to the outputs of the main and auxiliary and Measuring circuits, while the thickness of the main waveguide is greater than the additional thickness by an amount that ensures the difference in phase shifts at the receiving end of the waveguides no more than 2 liters when filling and rotating sensors, and the second input of the main phase meter is connected to the output of the additional measuring circuit.

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