SU1670562A1 - Capacitive humidity transducer for bulky dielectric materials - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure the moisture content of bulk packages of materials. The purpose of the invention is to improve the measurement accuracy. A capacitive humidity sensor contains two measuring electrodes, two shielding grounded electrodes, with the measuring electrodes bent and convex toward the shielding electrodes, formed by the curved surface of the cavity of the measuring electrodes filled with a dielectric with a dielectric constant of 1.5 to 5, and R = (L / D) ε, where L is the width of the measuring electrode

D is the distance between the measuring electrodes

ε is the dielectric constant of the filler cavity of the measuring electrode. 1 il.

Description

The invention relates to a measurement technique and can be used to measure the moisture content of materials, for example cotton fiber, viscose, wool, paper, packed in bulk bales (100-200 kg) with comparable sizes.

The aim of the invention is to improve the measurement accuracy.

The drawing schematically shows a capacitive humidity sensor.

A capacitive humidity sensor for bulk dielectric materials contains two measuring electrodes 1 and 2, the surface of each of which is curved in a direction toward the shielding grounded electrodes 3 and 4, two cavities 5 and 6 measuring electrodes, filled with a dielectric. The surfaces of the measuring electrodes are curved along a radius selected from the ratio

R iE R db.

where L is the width of the measuring electrode;

d is the distance between the measuring electrodes;

E is the dielectric constant of the filler cavity of the measuring electrode.

Plexiglas, for example, can be used as a filler for measuring electrodes.

The sensor works as follows.

The configuration of the measuring electrodes in the sensor provides the concentration of the floor in the measuring area between the electrodes and creates a low axial field gradient

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0-0 in the center of the measuring zone. Filling the cavity of the measuring electrodes with a dielectric allows reducing and equalizing the field gradient near pectrodes 1 and 2 in the horizontal direction along the axis 02 02. The contribution of the dielectric filling the cavities of electrodes 1 and 2 increases in the direction to the central axis 0-0. however, in accordance with Coulomb's law, the intensity of the floor in this direction decreases.

Thus, a low gradient field is set uniformly over the entire volume of the measurement zone.

When placed in the measuring chamber of the sample under study, for example, cotton fiber kips, the sensor field interacts with the material evenly throughout the volume. however, the average humidity information will become more reliable and, therefore, the measurement accuracy will be improved.

Claims (2)

1. Capacitive sensor moisture bulk dielectric materials containing two measuring electrodes, two shielded grounded electrodes located on the outer side of the measuring electrodes, characterized in that, in order to improve the accuracy of measurements, the surface of the measuring electrodes is bent, and the curvature of the bend is directed to the shielding electrodes, dielectric constant value from 1.5 to 5. 2. The sensor according to claim 1, characterized in that the electrodes are cylindrical in shape with a radius R-jjE. where L is the width of the measuring electrode: d is the distance between the measuring electrodes; E is the dielectric constant of the filler cavity of the measuring electrode. about.