SU1707489A1 - Pressure transducer - Google Patents

Abstract

The invention can be used to measure with increased accuracy the high-pressure, high-pressure conditions under thermal shock. When the sensor is operating under thermal shock conditions, the point of the average temperature of the ends of the quarters with tensor resistor 8.9 will be determined by the mean integral temperature value; on their length. as a part of the difference between the mean integral values of temperature and the arithmetic mean values will have a plus sign, a. a part is a minus, then partial compensation of the arising error of subsection) and addition of the components occurs. 2 Il.

Description

The invention relates to a measurement technique and can be used to measure rapidly variable high pressures under conditions of elevated temperatures.

The aim of the invention is to improve the accuracy under the conditions of thermal shock and reduce the size.

FIG. 1 shows the structure of the proposed sensor; in fig. 2 - location of the strain gauges on the rod of the elastic element.

The divider sensor comprises a housing 1, a sensing membrane 2 and a core elastic element 3. On the core elastic element (see Fig. 2) a genzor is formed by mitral technology: Ora: 4-7 in the central part of the flat face and 8 and 9 along the edges. The resistance strain gages 4, 5 are set D in the transverse direction so that their midpoints are located at a distance h

.R. from the ends of the strain gauges 8. 9 installed in the longitudinal direction, and the middle of the strain gauges 6, 7 - at a distance of h 3 / 8fT.p. from the ends of the strain gauges 8.9, where 1t.r. - the length of the longitudinal. strain gauges.

The strain gauges 4 and 6, 5 and 7 have the same resistance, are connected in series and are parts of the composite strain gauges of the two opposite shoulders of the bridge.

Strain gages 4-9 are combined into a bridge measuring circuit.

The sensor works as follows.

When a measured pressure is applied to the sensing membrane 2 (see Fig. I), the last gfeoSrzus. Dasg, C1; s not with the force that is transmitted to the rod elastic element 3. The rod elastic element 3 undergoes deformation, along with it and the resistance strain gages 4–9 (the resistance strain gages 4–7

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- lateral deformation of tension, and strain gages 8, 9 - longitudinal compression deformation). As a consequence, a signal appears at the output of the bridge measuring circuit, which is proportional to the measured pressure.

When the sensor operates under stationary temperature conditions, when the temperature of the measured medium differs significantly from the ambient temperature, a temperature gradient will occur along the length of the elastic element, while the temperature distribution in the steady state is almost linear.

Due to the fact that the longitudinal strain gauges 8 and 9 have the same length (and the same resistance), and their ends are located at the same distance from the membrane, they are in the same temperature conditions. The variations in resistance of these strain gauges are equal.

In the bridge measuring circuit of the sensor, the resistances of the strain gauges 8 and 9 are added together (since they are

 included in the opposite shoulders of the bridge measuring circuit and have the same sign).

In order to prevent a spurious signal from appearing at the output of the bridge measuring circuit (no temperature error occurred), it requires that the sum of changes in the resistance of the opposite arms to temperature be the same.

This can be obtained by installing strain-resistance resistors 4–7 at the points of average temperatures of quarter-blocks of resistance strain gages 8 and 9.

These points have coordinates along the length of the longitudinal strain gauges: 1 / 81t.r. 3/8b.r..5 / 8g.R.7/8 {tr.

When installing the strain gauges 4-7 in this way, as is done in the design, the strain gauges 4 and 5 are at a distance h 1 / 8tr.p .. and the strain gauges 6 and 7 - at a distance h 3 / 81t.r. from the ends of the longitudinal strain gauges 8 and 9.

Thus, in the case of a linear temperature distribution along the length of the core elastic element, there will be a complete self-compensation of the temperature error due to the presence of a temperature gradient.

When the sensor operates under conditions of unsteady temperatures, there will also be a temperature gradient along the length of the core elastic element, but at

this temperature distribution (at the time of thermal shock) will be nonlinear.

In this case, the point of the average temperature of the ends of the quarters of the strain gages 8 and 9 will be determined by the average integral temperature value on their length and not coincide with the average temperature value. As a result, an error occurs that is proportional to the sum of the differences-average integral and

arithmetic mean temperature of the ends of the four quarters of the longitudinal strain gauges.

Since part of the difference between the mean integral temperature and arithmetic mean values will have a plus sign, and

the part-minus partly compensates for the error that occurs when the components are added together.

The application of the invention improves the accuracy by reducing the temperature error. The temperature error decreases to 1 - 3%. This increases the accuracy of receiving my information.

Claims (1)

Invention Formula A pressure sensor, comprising a housing with a membrane made in one piece with it, in contact with a rod elastic element, on a flat face of which the United bridge strain gauges, two of which are located along the edges of the face along the axis of the rod of an elastic element, and the other two, included on the opposite shoulders of the bridge, are symmetrically in the central part relative to the ends of the first two, strain gauges and perpendicular to them. This is due to the fact that, in order to increase the accuracy under the conditions of thermal shock and reduce its dimensions, the resistance gages of the central part of the face are made of two parts each, with the components of the tensors arranged parallel to one another relative to another at a distance equal to a quarter of the length of the strain gauge, located on the edge of the face. Fy J Nso H 2