SU1746329A1 - Capacitive cell for proximate check of parameters of dielectric materials - Google Patents

Abstract

Usage: moisture control of bulk dielectrics. SUMMARY OF THE INVENTION: Inside the case 1, there is a conical screw 2, on the shaft of which a sector guide 3 is successively placed, dielectric bushes 4, 5. 6. Limiter 7. Coaxial electrodes 8, 9 1 ID are fixed on one of the bushes.

Description

The invention relates to measuring technique and may find application for rapid control of moisture content of seeds of agricultural crops.

A known circuit measuring cell with a micrometer screw. The cell is a system of two plane-parallel electrodes - fixed and moving. When measuring, the sample is placed between the electrodes of the measuring cell and the movable electrode is lowered until the sample is sandwiched between the plates.

The disadvantage is that this design does not allow for the flow of bulk materials, as well as to achieve a stable density on all samples.

Closest to the proposed invention relates to a cell with a screw seal. The movement and compaction of the material is carried out using a screw and a disk that covers the outlet and is held by a spring. The ring electrodes are arranged sequentially one after another with alternating polarity, i.e. on one side of the material. In this case, an electric field arises between the so-called comb electrodes.

. The disadvantage of this design is the uneven distribution of the electric field strength, since one-sided contact with the material and a significantly greater length of the electrodes than their width, and the distance between them leads to inhomogeneity of the electric field even in homogeneous materials. A field of tangible tension exists only in the near-electrode region.

When the spring seal and the cylindrical shape of the screw, the reliability of reproducing the seal of the material, and therefore the reliability of reproducing the results, deteriorates, since the effect of the sealing device on the material is different at different humidity. The electrode should provide good electrical contact over the entire surface of contact with the sample without air gaps between them, and in this design, due to the cylindrical screw, there will always be an air gap.

The aim of the invention is to increase the sensitivity to changes in the parameters of the controlled material by a more uniform distribution of the electric field, eliminating air gaps and maintaining at the same level the specific pressure of pressing.

This goal is achieved by the fact that a sector guide, a sector stop with a locking lock nut, sector dielectric sleeves are additionally installed in the metal case, moreover, the electrodes are made coaxial and fixed in sector dielectric sleeves, and the screw is made conical.

The drawing shows a capacitive cell for express control of dielectric parameters, general view.

The capacitive cell consists of a metal housing 1, inside of which a conical screw 2 is located. On the narrow side of the conical screw 2, a sector guide 3 is installed on the shaft, three sector dielectric bushings 4-6, sector limiter 7. Coaxial electrodes 8 are mounted on the middle dielectric bush 5 and 9, which are fixed in sector dielectric bushings. The end of the housing is tightened with a lock nut 10.

The device operates as follows.

Bulk material is moved and compacted using a conical screw 2. The stability of the density of the material is determined by the speed of rotation of the screw motor. Further, the material passing through the sector guide 3 and the dielectric sleeve 4, falls into the interelectrode space. The sector guide 3 serves to facilitate the passage of the material densified by the screw through the dielectric bushings 4-6. High frequency voltage is applied to the coaxial electrodes 8 and 9 of the cell and the cell is included in the measuring circuit, with which the parameters of the output terminals can be measured. After control, the material passes through a dielectric sleeve 6, which isolates the coaxial electrodes from the housing 1 and from the sector limiter 7.

Sector limiter 7 is used to support the shaft of the conical screw and together with the lock nut 10 for fixing the dielectric bushings 4-6.

When moving bulk material, the sector guide 3 and the cone screw 2 compact and eliminate the air gap, and this is also facilitated by the fact that coaxial electrodes are mounted on the dielectric sleeve 5, i.e. the bulk material touches on both sides of each electrode, thereby providing good electrical contact with the sample.

The specific pressing pressure of the material is maintained at the same level by maintaining a certain rotation speed of the conical screw motor, and this is also facilitated by the conical design of the screw, the coaxial electrodes mounted on the dielectric sleeve 5 and the sector guide.

The advantage of the proposed cell is to obtain maximum sensitivity to changes in the properties of the material due to a more uniform distribution of the electric field and the exclusion of air gaps; the ability to more accurately reproduce the measurement results by maintaining at the same level the specific pressing pressure.

Claims (1)

Claim A capacitive cell for express control of dielectric parameters, containing a screw and electrodes placed in a metal casing, characterized in that, in order to increase sensitivity to changes in the parameters of the material being monitored, it additionally 10 contains a sector guide, sector dielectric bushings, sector dielectric sleeves, sequentially mounted on the screw shaft a limiter, a lock nut, and the electrodes are made coaxial 15 and fixed in one of the sector dielectric bushings, and the screw is made to matic.