SU469890A1 - Discrete Level Gauge - Google Patents

Description

The invention relates to the field of instrumentation and can be used to measure the water level in irrigation canals of irrigation systems.

A discrete float level transmitter is known, which contains a float with a permanent magnet, magnetic contacts arranged in a non-magnetic tube, through which the diode array is connected to the common bus, the secondary device and the secondary device. However, an increase in the incidence with a decrease in the distance between the magnetically controlled contacts is observed, due to the fact that several of them are within the range of the control magnetic flux of the permanent magnet, and a binary code is formed at the output of the encoder that does not correspond to the numerical value of the continuous measured level value . In addition, when the quantization step is 1 cm, when a permanent magnet is located between the contacts, its magnetic flux does not affect any of them, which leads to loss of information.

The purpose of the invention is to improve the accuracy and reliability of measuring the level of a liquid. This is achieved by the fact that the output of each magnetically controlled contact, except the top one, is connected to the corresponding input of the encoder via an And gate, the second input of which is connected to the output of the next

a magnetically controlled contact through the logical element "NOT, and the output of the upper magnetically controlled contact is directly connected to the corresponding input of the encoder.

FIG. 1 shows the block diagram of the proposed level gauge; in fig. 2 is a circuit diagram of a converter.

The level gauge has a float of 1 with a constant

a magnet 2, on top of which a ferromagnetic screen 3 is fixed. In the float 1 there is a hole through which the converter 4 with magnetic-controlled contacts passes, connected through logic unit 5, matrix encoder 6, decoder 7 to digital display 8. In addition, the output of the matrix encoder is connected to scan converter 9. Converter 4 is designed to measure the level of a liquid and consists of magnetic contacts 10-29, mounted on a rail with a constant pitch, and connected by one condom to a common bus 30. W The second end of the pins is 10-29 through a logical

The I 31-35 circuits and the separation diodes 36 are connected to the output buses 37 of the matrix encoder 6. Also, the I-29 pin outputs are connected via the HEs 38-41 logic gates to the second

the inputs of the circuits "And 31-35. Diode combination

in the matrix circuit, connecting the output of each element And and the contact 29 with the output tires, corresponds to the binary-tenth reflex code GOST - 12814-67.

Discrete gauge works as follows.

When the nonlavka 1 is located, which corresponds to the initial level value, the magnetic flux of the magnet 2 closes contact 10, which supplies the supply voltage from the common field 30 to the input of the logic element PI 31. At the same time, the subsequent contact 11 is open, which corresponds to the input of the element PE 38 the zero value of the signal, and at its output - a single value, which is fed to the second input of the element "And 31. The element" And 31 will generate a single signal, which will go to the corresponding input of the encoder 6, and a combination of binary signals, p The decoding of which determines the initial level value. When moving nonlavka 1 along the converter 4, the controlling magnetic flux of the magnet 2 closes the contacts 10, 11, 12 and the supply voltage from the common bus 30 flows directly and through the elements 38 and 39 to the outputs of the And 31, 32 and 33 logic circuits. “Both the 31 and 32 inverted signal is zero, therefore there is no signal on the outputs of the encoder controlling them. For the circuit “AND 33, the inverse signal is equal to one, since contact 13 is open.

At the same time, a binary code combination is formed at the input of the digitizer 6 and at its output flaps 37, corresponding to the value of the measured level, which is decoded by the decoder 7. The output information received from the decoder goes to the digital scoreboard 8 and can be used for visual counting and processing the counting devices.

A sweep converter is designed to convert a parallel code from an encoder to a serial one and transfer it to a telemechanic system with subsequent

deciphering. The upper limit value of the level is fixed by a magnetically controlled contact 29 connected directly to the input bus of the encoder. The use of the logic circuit "And and" in the proposed device does NOT reduce the quantization step, and therefore improves the accuracy of the measurement of the liquid level. The use of a permanent magnet with a ferromagnetic shield ensures reliable closing of the magnetically controlled contacts. If magnetic contacts are arranged according to a certain law, the proposed level gauge can be used as a flow meter.

Subject invention

A discrete level gauge containing a float with a permanent magnet and a ferromagnetic shield, magnetic contacts placed in a vertically arranged non-magnetic pipe over the entire measuring range, an encoder and a secondary device characterized in that, in order to improve the accuracy and reliability of the measurement, the output of each magnetically fixed contact , except the top, connected to the corresponding input

via the logical element “And”, the second input of which is connected to the output of the subsequent magnetic-controlled contact through the logical element “PE”, and the output of the upper magnetic-controlled contact is connected directly to the corresponding input of the digital recorder.