SU1281941A1 - Frequency pressure transducer - Google Patents

Abstract

This invention relates to instrumentation technology. The aim of the invention is to reduce the temperature error. The frequency sensor contains a membrane 1 with two racks 2 and 3 installed on it, between which a string 4i is fixed. In one of the racks there are two slots with guide grooves in which inserts 7 and 8 with the possibility of moving along the grooves. The slots are made with the outer and inner sides of the rack opposite. One of the elements is made of it. Of the material with a temperature coefficient of linear expansion is excellent, - and the other is equal to the temperature coefficient of linear expansion of the material of the rack. This leads to the compensation of different temperature expansion of the string 4 and the membrane 1. The change in the thermal compensation value while maintaining the initial value of the oscillation frequency of the string 4 is carried out by simultaneously moving the liners 7 and 8 in the same direction. 1 il. WITH

Description

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The invention relates to an instrumentation technician, in particular to frequency pressure sensors with string resonators, and can be used to measure pressure with high accuracy in automatic control devices operating under conditions of varying external temperatures.

The purpose of the invention is to make it possible to control the amount of thermal compensation while maintaining the initial value.

The drawing shows a frequency pressure sensor, a general view.

The sensor contains a membrane 1, racks 2 and 3 mounted on it, between which a string 4 is fixed. In one of the stacks, for example 2, opposite slots in the planes displaced in height perpendicular to the axis of the rack are made on the outer and inner sides with ex. the automatic grooves that form the elastic hinges 5 and 6. In the guide grooves, inserts 7 and 8 are fitted with tension, which can move along the grooves.

The frequency pressure sensor operates as follows.

The pressure measured causes a deflection of the membrane 1 and rotation of the pillars 2 and 3 displaced relative to the center of the membrane. As a result, there is a change in the tension of the string 4, fixed between the ends of the uprights, and a change in the frequency of its oscillations. The excitation and removal of vibrations of a string are carried out in a known manner.

When the temperature sensor temperature changes, for example, when it increases, and when the linear expansion temperature coefficient (TCLE) of the material of one of the pins, for example, 7, is not equal to TCLE of the rack 2 material, unequal temperature expansion of the pin and the rack causes the upper part of the rack to rotate relatively elastic hinge 5. If, for example, thermal expansion of the string exceeds the expansion of the membrane, thermal expansion coefficient of the material of the insert must be greater than thermal expansion coefficient of the material of the rack, and vice versa, if thermal expansion of the stranded wire ochno CTE liner material should be less than the coefficient of linear expansion strut material. As a result, different themes are compensated.

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Peripheral expansion of the string and membrane.

When moving the insert along the guide groove, the amount of temperature compensation changes. With decreasing distance from. Insert 7 until the elastic hinge 5 temperature compensation increases. Adjusting this distance allows the temperature compensation to be adjusted to the desired value and to provide full thermal compensation. Moving the liner 7 along the guide groove causes a change in the tension and, therefore, the initial oscillation frequency of the strings 4. For example, by decreasing the distance from the liner 7 to the elastic hinge 5, the frequency increases. The frequency is returned to the original value by moving the insert 8, made of a material with a thermal expansion coefficient equal to the thermal expansion coefficient of the stand material, and, therefore, does not cause a change in the tension of the string, with a change in temperature. Moreover, as the distance from the insert 8 to the elastic hinge 6 decreases, the tension of the string 4 and, consequently, the frequency of oscillation of the string decreases.

As the liners 7 and 8 move simultaneously in one direction, the thermal compensation value changes while the initial oscillation frequency of the string remains.

Thus, the frequency sensor allows to increase the accuracy of pressure measurement in conditions of variable temperatures, to unify the sensor according to the output signal, to significantly simplify and speed up the process of setting up and adjusting the sensors.

Claims (1)

The invention includes a frequency pressure sensor containing a membrane with struts mounted on it, between which a string is fixed, characterized in that, in order to reduce temperature error, two grooves with oppositely directed slits along their axes are made in one of the struts In the grooves with a tension, inserts are installed with the possibility of their movement, and one of the inserts is made of a material with a temperature coefficient of linear expansion different from the temperature coefficient of linear On the extension of the rack material adrugoy-skoeffitsientom equal to him.