SU1571447A1 - Pressure transducer - Google Patents

Abstract

The invention can be used to measure, with enhanced accuracy, fast-varying and static pressures of liquid and gaseous media under unsteady temperature conditions of operation (with thermal shock). The pressure sensor includes a housing, a membrane, two measuring bridges, having the same topology, and located on a dielectric substrate deposited on the membrane. In this case, the topology of one bridge is a mirror image of the topology of the other and in each bridge two resistance strain gages of opposite shoulders are covered with a layer of silicon overlapping the surface occupied by the resistance strain gages, and in one measuring bridge a pair of circumferential strain gages is covered, and the other is radial. 3 il.

Description

The invention relates to a measurement technique, namely, devices for remote pressure measurement, and can be used in sensors for measuring fast-variable and static pressure of liquid and gaseous media during non-stationary temperature operation (with thermal shock), for example, when measuring pressure in fuel-energy systems of engines internal combustion, etc.

The purpose of the invention is to improve the measurement accuracy by reducing the temperature error when exposed to thermal shock and increasing sensitivity.

Fig. 1 shows the design of a strain-resistance pressure sensor; figure 2 - the location of the strain gauges on the membrane (topology); fig.Z - measuring circuit.

The device includes a housing 1, a membrane 2, which is made integral with fitting 3. On the membrane 2 two measuring bridges are formed, one from strain gages 4-7, the other from strain gages 8-11. Tensors 4 and b are coated with a layer of silicon

12.a strain gages 9 and 11 - a layer of silicon

13. Contact pads 14 are used to connect the inputs of the measuring bridges to the power supply 15, as well as to connect the outputs of the measuring bridges with an operational amplifier (OA) 16 and 17, to the outputs of which the adding unit 18 is connected

The pressure sensor works as follows

When the measured pressure is applied through the nozzle 3 to the membrane 2, the latter bends, the strain gages 4-11 experience deformation, and consequently, their resistance changes. As a result, signals proportional to the measured pressure appear at the outputs of the measuring bridges.

When exposed to thermal shock, the resistance of the strain gauges changes, and

with

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h

consequently, the outputs of the measurement bridges change. Due to the fact that the strain gauges of the measuring bridges are set at two equal distances from the center of the membrane, and the topology of the first bridge is a mirror image of the topology of the second, the temperature at the strain gauges 4 and 8, 5 and 9, 6 and 10, 7 and 11 Has pairwise the same value at any thermal disturbances. Coating a layer of silicon in the first measuring bridge of a pair of circumferential strain gauges, and in the second - a pair of radial leads to the fact that the strain gauges 4 and 8, 5 and 9, 6 and 10, 7 and 11 have the opposite values of TKS.

As a result of this, the changes in the output signals of the measuring bridges with temperature are the same, but have the opposite sign. .

After summing the output signals amplified at the OS with the coefficient K from the first and second measuring bridges, the output signal of the BS at the output of the BS will double the output signal from the pressure and the almost zero (compensated) change in the output signal from the temperature.

In addition, when the strain gauges are coated with a silicon layer from 0.05 to 0.1 μm, the sensitivity of the sensor increases.

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five

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five

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This is explained by an increase in the strain resistance coefficient of the strain gauges to a value of 4–5 (thin film strain gauges not covered by a layer of silicon, have a strain sensitivity coefficient from 2 to 3) due to an increase in the role of the material resistivity when its physical properties change.

Claims (1)

Claims of pressure sensor, comprising a housing, a membrane with a dielectric substrate on its surface, circumferential and radial strain gauges, connected in two measuring bridges of the same topology and fixed on the dielectric substrate, characterized in that, in order to improve accuracy by reducing the temperature error when exposed thermal shock and sensitivity increase, in it the measuring bridges are located symmetrically relative to the center of the membrane, and the topology of one measuring bridge is a mirror image of the other, wherein the bridge in each of two opposing arms gage covered silicon layer, the one measuring bridge is covered with a pair of circumferential strain gauges, and the other - a pair of radial. 4,5,6,18,9,10 1J ъ 1 Editor A.Dolinich Fig.z Compiled by O. S lusa roar Tehred M. Morgenthal Proofreader I. Muska