RU1820222C - Electromagnetic flowmeter - Google Patents

Abstract

Usage: measuring technique, determining the flow rate of electrically conductive liquids. The inventive electromagnetic flow meter contains a pipe of rectangular or elliptical cross-section, placed between the pole tips of two electromagnets, with excitation coils mounted on them, connected through a switch to a stabilized constant current source, while a magnetically sensitive one is installed on the pipe between the same-name poles of electromagnets an element to which an analog-to-digital converter is connected through an amplifier, to the output of which through the memory registers I connect n first and the second input of the microprocessor unit connected to the synchronizing input to the third output of the control unit, to the second and third outputs of which are connected control registers memory input and output to the fourth control input connected switch. 2 s.p. f-ly, 2 ill. AND

Description

The invention relates to measuring equipment and is intended to determine the flow rate of explosive and corrosive liquids.

The aim of the invention is to increase accuracy by reducing zero drift.

In FIG. 1 shows a block diagram of an electromagnetic flow meter; in FIG. 2 is a timing voltage diagram.

The electromagnetic flow meter comprises a pipe 1 of rectangular or elliptical cross-sections, placed between the pole pieces of electromagnets consisting of C-o & cut magnetic conductors 2, 3 with excitation coils 4,5 mounted on them. connected through a switch 6 to a stabilized constant current source 7. On the pipe 1 between the same poles of the electromagnets a magnetoelectric converter is installed. 8, to which through

a DC amplifier 9 is connected to an analog-to-digital converter 10, to the information inputs of which, via parallel-connected memory registers 11,12, the microprocessor unit 13 connected by the clock input to the first output of the control unit (timer) 14 is connected to the second and The third outputs of which are connected, respectively, the first and second memory registers 11, 12, and the fourth - the control input of the switch 6.

Electromagnetic flowmeter operates as follows.

According to the commands received from the fourth output of block 14 (see Fig. 2), the current for a time equal to the duration of the rectangular pulse is alternately supplied from the output of the current source 7 through the switch 6 to the electromagnet excitation coils 4, 5. In this case, the first electromagnet under

y o y

N) hO

It is turned off when a logic unit level is received at the control input of the switch 6, and the second - logical zero.

Before starting the flowmeter, the transducer 8 is installed so that in the absence of fluid flow in the pipe 1, the Eo signal at its output remains constant regardless of which of the electromagnets is currently turned on.

If there is a flow in the pipe 1, the magnetic field strength in the installation zone of the transducer 8 when the first electromagnet is turned on will increase in proportion to the flow velocity, and when the second one is turned on, it decreases. Thus, when electromagnets are connected in series at the output of converter 8, two "signals containing alternating zero E0, high-speed Her and drift Ed components will be alternately formed.

The selection of the high-speed component of its signal is carried out according to the following algorithm.

When the first electromagnet is turned on, the first signal Ep E0 + Ec + E is generated at the output of the converter 8. When the second electromagnet is turned on, at the output of the converter 8, a second signal Ev Eo - EC + Un is generated. Since the component Ed is practically unchanged, the isolation of the velocity component of the signal Ec can be carried out by subtracting the EvEsEp.

The secondary Converter of the flowmeter operates as follows.

When the first electromagnet is turned on, the signal from the converter 8, amplified by the amplifier 9, is fed to the input of the analog-to-digital converter 10. When the level of the logic unit delayed for the duration of the transients from the second output of the control unit 14 is transferred, the information from the output of the analog-to-digital converter 10 is overwritten into the first memory register 11.

When you turn on the second electromagnet with the arrival of the level of the logical unit from the third output of the control unit 14, the information from the output of the analog-to-digital converter 10 is written to the second memory register 12. When the level is received

logical unit from the first output of the control unit 14 to the clock input of the microprocessor unit 13 information from the memory registers 11 and 12 is overwritten.

internal registers of the microprocessor, in which, in accordance with a given program, it is processed and then displayed on a digital display, after which the entire described flow determination cycle will be repeated.

Formula

Claims (3)

1. An electromagnetic flowmeter comprising a nozzle, a stabilized DC source placed between the poles of the electromagnet, a magnetically sensitive element and a recorder installed on the nozzle, which, in order to increase accuracy, introduces a second electromagnet, a switch and a control unit, while the magnetically sensitive element is installed between the same poles of the first and second electromagnets and connected through an amplifier to the input an analog-to-digital converter, the output of which is connected to the information inputs of the first and second memory registers, the control inputs of the first and second memory registers are connected respectively to the first and second outputs of the control unit, the third output of which is connected to the synchronizing input of the microprocessor unit, the first and second information inputs of which are connected respectively to the outputs of the first and second memory registers, fourth output the control unit is connected to the control input, the laziness of the switch through which the first and the second electromagnet is connected to the output of a stabilized direct current source. 2. The flow meter according to claim 1, distinguished by the fact that the nozzle has a rectangular or an elliptical section, whose axis is oriented perpendicularly Os m magnetization of electromagnets. 3. A flowmeter pop. 1, characterized in that, in order to increase sensitivity, an electrometric pentode with zero input bias is used as a magneto-sensitive element. AND Fu. 1