SU593093A1 - Pressure transducer - Google Patents

Description

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The invention relates to the field of instrumentation, in particular, to devices for measuring pressure.

Known. Pressure transducers with a time-pulse output signal, using a weight support element in combination with an unconsolidated piston, built using the push-pull method of integrating pressure.

The known pressure transducers do not provide high accuracy measurements.

Closest to the invention by technical essence is a pressure transducer, which consists of a chamber filled with a working fluid, connected to the measured medium through an unregulated choke, and an unsealed piston hung out by a float and placed in a rotating sleeve. Above the piston is placed an electromagnet, the core of which is used as a reference load, and the winding is connected to the control unit. The extreme positions of the pistons are fixed by the contacts connected to the position sensor control unit. The piston travels forward to a given displacement by force from the measured pressure, and the reverse due to the stable weight of the electromagnet core. ,

In this pressure transducer, the unconsolidated piston simultaneously performs the functions of a source of reference pressure in combination with a weight support element, an integrating device in combination with an unregulated throttle and a pointer to the output signal of the flow volume integrator, which is realized by position sensors on the displacement of the piston 2.

This combination of functions simplifies the design of the converter, but limits the accuracy of the design because it leads to the following contradiction: on the one hand, to increase the accuracy of the reference pressure setting, as well as the accuracy of the pressure integration, it is necessary to strive to reduce the piston displacement (in particular pressure sensors, in particular pressure standard, permissible piston movements are limited to fractions of a micron) and, on the other hand, to reduce the integral comparison error and to reveal measurement intervals tim should increase, moving the piston, since the sensitivity of the position sensor is limited, §i also exerts a large influence interference, particularly at small vibration displacement x, object of the present invention is pov1shenie accuracy of pressure measurement. This is achieved by the fact that the proposed pressure transducer, containing a chamber filled with a working fluid, is connected to the measured medium through an unregulated choke, an unconsolidated piston with a load, the installation mechanism of which is divine with the output of the control device, and piston position sensors, is equipped with a reverse engine , and in the chamber there is a micro-screw fitted with position sensors, while the micro-screw is connected via a reducer to the shaft of the reversing motor, the winding of which is connected through an amplifier IK. the output of the position sensor is derived, and the position sensors of the micro screw are connected to the input of the control device. FIG. 1 shows schematically the described converter; in fig. 2 is a diagram of his work. The converter contains a chamber 1 with a liquid, which through an unregulated throttle 2 is connected to a measured pressure P-), a rotating sleeve 3, an unsealed piston 4, a load applying mechanism 5 controlled by signals from the output of control unit 6. The piston movement is measured by sensor 7 position, for example, capacitive, and the output signal of the sensor is amplified by an amplifier 8, the output of which is connected to the control winding of the reversing motor 9. The motor shaft is connected through a gearbox through foot 1O and fingers 11 to micro Intom 12 placed in chamber 1. Comparison of integral values set in two cycles — discrimination of the angle of rotation of the microscrew is accomplished by the photosensor 1 whose signal is transmitted to the control device 6 through the amplifier 14 on the control unit 6. The control unit generates pulses t and t 2 whose duration is equal to the rotation time micro screw at a given angle of the first and second integration cycles,. The Converter operates as follows. In the initial state, the piston is arrested. When removing the arresting signal from the control unit 6 in the first integration step, the liquid under the action of the measured pressure flows into the chamber 1 through the choke 2 with hydraulic resistance R (: and tends to push the pore 4 upwards. The displacement of the piston is converted by the sensor 7 into a voltage which is amplified by the amplifier 8 and is applied to the control winding of the reversing motor 9. With a positive control voltage, the motor rotates in the direction of unscrewing the micro-screw, and after a certain delay time e the rotational speed Sd- is set to a constant.At the same time, the angle H of the shaft shaft grows: K where K is the transmission coefficient of the closed circuit of the following static balance (nodes 3,7,8,9,12), which converts the flow rate Gl and the angular velocity ( ttg. CORNER d "Cd is defined by two levels of discrimination f and it is practically convenient to make it equal to one (several) shaft revolutions. Thus, during time i, when the micro-screw rotates by the DFo angle from f to H, the first integration cycle is performed, and the measurement formula has the form l. „. | Xa. . In the second cycle, according to the signal from the control device, during the delay At 2, the weight is loaded. where 5 is the effective piston area. The piston tends to descend, and the liquid flows out of the chamber through the throttle with the flow under the action of the pressure difference Pj, g (Flow Qy - -; after the delay time Ai, j Tracked by the following astatic balance circuit. As the 2nd stroke moves the piston in the opposite direction, the voltage at the output of the sensor. 7 the position and the output of the reversing engine 9 change in sign, and the engine shaft begins to change sign, and the engine shaft begins to grow in the reverse direction, the passage of the specified angle values f ,, ff in inverted direction at The thru device 6 will form the measuring interval tg. In the second cycle, the measurement form looks like: taking into account the equality of the values of the integrals of both integration cycles г ha;; e under the condition of constant hydraulic resistance and transfer coefficient K during the measurement cycle compare. small-and-small, C – L – L AB 2 (units — ten seconds) we obtain

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F o rm y

A pressure transducer containing a chamber filled with working fluid, connected to the medium being measured through an uncontrolled choke, an unconsolidated piston with a load, the installation mechanism of which is connected to the output of the control device, and the piston position sensors, which are accuracy of pressure measurement, it is equipped with a reversible motor, and in the measure a micro screw is installed, equipped with position sensors, while the micro screw through a reducer is connected to the shaft of the reversing motor, winding through which the silica gel is connected to the output of the piston position sensor, and the micro-screw micro-screw is connected to the input of the control unit.

Sources of information taken into account during the examination;

1. Loban V.I., Moiseychenko V.S. Integrating cargo-piston pressure transformer. Works of LPI, L., 1875.

2. Author's certificate of the USSR No. 430294, cl. QO1 L 7/16, 1974.