RU1818559C - Capacitance pressure transducer - Google Patents

Abstract

Usage: the invention relates to the field of measurement technology, in particular to capacitive pressure sensors and can be used to measure the pressure of liquid and gaseous media. The goal is to increase the sensitivity of the pressure sensor. SUMMARY OF THE INVENTION: a capacitive pressure sensor comprises a cylindrical body 1, on which a slice 2 is made, with the working capacitor electrode 3 and the reference capacitor electrode 4 located on its non-deformable portions. In parallel and near the cut, there is a plate 5, which has two U-shaped cuts that form the central part, rigidly connected to the center of the cut of the body at point 7 and suspended from it on two tori of the frame, which makes up the peripheral part of the plate and separated by jumpers 10 of low stiffness by two unequal parts. An electrode of the working capacitor 12 is located on a large part that can be moved, and an electrode 14 of a reference capacitor is placed on a smaller part bonded to the non-deformable section of the housing slice. The plate 5 on the side of the reference capacitor is rigidly attached to the housing 1. 2 sludge, / 2 ° 5 00 00 00 eaten eaten

Description

Fi.1

The invention relates to the field of measurement technology, in particular to capacitive pressure sensors for liquid and gaseous media and can be used in various industries for measuring pressure directly in pipelines.

The invention is directed to increasing the sensitivity of a capacitive pressure sensor.

According to the invention, in a capacitive pressure sensor containing a cylindrical body in the form of a pipe segment with a slice along the axis of symmetry forming a thinning of the pipe wall and a plate installed with a gap relative to the cut surface, the plate is made with two U-shaped cuts forming the central part of the plate, x firmly connected to the center of the pipe cut, and the peripheral part connected to it in the form of a frame divided by jumpers of low stiffness into two unequal parts, the larger of which is the inserted electrode the working capacitor, and on the smaller, connected along the circuit with the non-deformable part of the pipe cut, the introduced electrode of the reference capacitor is placed, while the non-deformable sections of the pipe cut are placed the input insulated response electrodes of the working and reference capacitors. In this case, a conversion function of the form:

, F K- vx

where is the K-constructive parameter;

Co is the capacitance of the reference capacitor;

Cx is the capacitance of the working capacitor.

The initial values of the capacitances Co and Cx are equal to each other, and then, when the position of the movable part of the membrane changes, the capacitance of the working capacitor remains constant.

The capacitance of the reference capacitor is determined from the expression:

Ј fo

where Ј is the dielectric constant of the interelectrode medium;

Fo is the area of the electrode of the reference capacitor;

5 ° is the thickness of the dielectric layer between the electrodes of the reference capacitor.

Since under the influence of pressure the central part of the plate moves

parallel to the surface of the cut, the value of the working capacity is determined from the expression

with cx

Oh oh

Ј Yeo

where (Do is the deflection of the center of the cut of the housing;. dx is the initial clearance of the working capacitor;

EO - dielectric constant of air.

For P0, Px, q0 (5x conversion function

call has the form

0) about

F (1 + i ir)

and is linear with respect to deflection w0, which improves the accuracy of the measurement.

Measurement accuracy is also improved beyond. due to a decrease in the temperature component of the error, since under the influence of an elevated temperature, the gaps between the electrodes of the reference and working capacitors will change equally.

The values of the working and supporting capacities also increase with an increase in the dielectric constant Ј and a decrease in the thickness of the dielectric layer e. In addition, capacitances can be increased due to the area FX.O, since the design allows the cylindrical body to be replaced by a parallelepiped-shaped body.

The sensitivity S of a capacitive pressure sensor, defined as the ratio of the change in the output quantity to the corresponding change in the input quantity, is equal to:

S

  1 d U Јo 5x

5

0

and also increases with increasing dielectric constant Ј and decreasing the gap g.

Fig. 1 is a cross-sectional view of a capacitive pressure sensor; on the. figure 2 is the same, a top view.

The capacitive sensor contains a cylindrical body 1. on which a slice 2 is made with the working capacitor electrode 3 and the reference capacitor electrode 4 located on its non-deformable sections. In parallel and near the cut is a plate 5, which has two U-shaped cuts forming the central part of the plate 6. rigidly connected

with the center of the cut-off of the body at point 7 and the frame 9 suspended on it on two torsions 8, which makes up the peripheral part of the plate and separated by jumpers of low rigidity 1, into two unequal parts. The electrode 11 of the working capacitor 12 is located on the greater part 11, which is able to move, and the electrode 14 of the reference capacitor is placed on the smaller part 13, fastened to the non-deformable part of the cut of the body, the plate 5 from the side of the reference capacitor is also rigidly attached to the body 1 at points 15. A capacitive pressure sensor operates as follows. The pressure P is applied to the sensor cavity, under the influence of which the thinned part of the cut of the body deforms, and since the central part of the plate is rigidly connected to the center of the cut, it will also move, and together with it the peripheral part of the plate with the working electrode. The distance between the electrodes of the working capacitor varies, as well as its capacitance and, accordingly, the output signal.

Claims (1)

The claims A capacitive pressure sensor containing a cylindrical body in the form of a pipe segment with a slice along the axis of symmetry, forming a thinning of the pipe wall, and a plate installed with a gap relative to the surface of the cut, characterized in that, in order to increase the sensitivity, the plate is made with two U-shaped cutouts forming the central part of the plate, rigidly connected to the center of the pipe cut, and the peripheral part connected to it in the form of a frame, divided by jumpers of low rigidity into two unequal parts, into more the first of which the introduced electrode of the working capacitor is located, and on the smaller; fastened along the contour with the non-deformable part of the pipe cut, the introduced electrode of the reference capacitor is placed, while the non-deformable sections of the pipe cut contain the input iso-responses. lined electrodes of the working and reference capacitors. Figure 2