SU987466A1 - Device for measuring dielectric liquid density - Google Patents

Description

The invention relates to devices for measuring the density of liquid media. Known densitometer explosive dielectric liquids, in which the density is a unique function of the dielectric constant. A coaxial waveguide is inserted into a vessel with liquid through a sealed hole in the lid. At the bottom of the waveguide there is a short-circuiting disk deflector, electrically connected to both electrodes of the waveguide. An oscillation unit is formed on the disk. A detector is installed on the waveguide from the outside with a probe inserted into the waveguide at such a distance that it falls into the oscillation unit at one of the extreme values of the range measured by the density of liquids. The detector is directly connected to a £ 1J indicating device.

A densitometer is known in which microwave oscillations are directed from the generator through a circulator to a sensor, which is a cylindrical resonator around a pipe segment with a controlled liquid C ² ! ·

The disadvantages of densitometers are the complexity of the design and the impossibility of use in autonomous conditions.

The closest Technical solution to the invention is a resonant density sensor for liquid and granular media containing a sensing element, an inductance, a high-frequency generator and a recording device [h}.

Its disadvantage is the low accuracy of liquid density measurements.

The purpose of the invention is improving the accuracy of measurements.

This goal is achieved by the fact that in the device for measuring the density of dielectric liquids containing a sensing element, an RF generator and a recording device, the sensing element is made in the form of an electrically conductive rod electrically connected as a quarter-wave length of a long line with an RF generator and symmetrically located relative to the rod a conductive tube connected to the ground of the RF generator as a half-wave length of a long line, and located outside the conductive tube through the insulator and the external conductive tube is electrically coupled to the housing May filled with a controlled environment, and the distance between the end of the rod and the inner conductive tube segment corresponds to the quarter-wave long line, and electrically screens are mounted on the ends of the outer tube.

The drawing schematically shows the proposed device.

The device comprises a housing 1 with a controlled environment in which a sensing element is located, comprising an RF generator 2 mounted in a conductive tube 3 connected to the ground of the RF generator as a half-wave length of a long line. An electrically conductive rod 4 is mounted along the symmetry axis of the tube 3, electrically connected as a quarter-wave length of a long line with an RF generator. An electrically conductive tube 6 is installed on the outer surface of the tube 3 through the insulator 5, at the ends of which there are electric shields 7 with openings for the input and output of the controlled medium.

The operation of the device is as follows.

The conductive rod is included in the oscillatory circuit of the RF generator, and the frequency of the electromagnetic oscillations of the generator is selected from the condition that the length of the conductive rod corresponds to 1/4 of their wavelength. Thus, an electromagnetic field is formed in the cavity between the electrically conductive tube 3 and the rod 4, the parameters of which have a maximum value at the opposite end of the screen 7 from the point where the rod is connected to the RF generator. In the segment of the obtained long line (conductive rod), oscillations occur in a quarter wavelength. In this case, the input impedance, which is a function of the coordinates and having a reactive character, in the cross section multiple of a quarter of the wavelength, has a value of 0 or oo, which determines the resonant nature of the operation of the meter.

The propagation of electromagnetic waves along the length of the tube 3, when the condition of connecting the latter to the ground of the RF generator as a half-wave length of a long line, is identical (according to the harmonic law) to the propagation in the cavity between the rod 4 and the tube 3. Only Ko in this case, slight changes in the electrical properties The controlled medium determines changes in the resonance properties of the meter (the output signal of the HF generator) 50-60% higher than identical changes in the cavity between the rod 4 and the tube 3. This ffekt is because as the conductor VChkolebany controlled environment is used, the electrical properties are measured. The choice of the length of the cavity between the open end of the electrically conductive rod 4 and the end of the tube 3_ corresponding to 1/4 of the wavelength is due to minimizing the scattering of electromagnetic energy at the end of the sensing element, and, therefore, minimizing the influence of external factors on the output parameters of the meter, i.e. the presence of electromagnetic interference, any structural links.

Claims (3)

There is a case with a case filled with a controlled medium, the distance between the end of the rod and the internal electrical conduit tube corresponds to a quarter-wave segment of a long line, and electric screens are installed at the ends of the outer tube. The drawing schematically shows the proposed device. The device comprises a housing 1 with a controlled environment in which a sensitive element is located that contains an RF generator 2 mounted in an electrically conductive tube 3 connected to the ground of the RF generator as a half-wave segment of a long line. Along the axis of symmetry of the tube 3 is mounted an electrically conductive wiper 4, electrically connected as a quarter-wave segment of a long line with an RF generator. An electrically conductive tube 6 is installed on the outer surface of the tube 3 through an insulator 5, the ends of which have electrical screens 7 with openings for the input and output of the controlled medium. The operation of the device is as follows. An electrically conductive rod is included in the oscillating circuit of the RF generator, and the frequency of the electromagnetic oscillations of the generator is chosen according to the condition that the length of the electrically conductive rod is 1/4 of their wavelength. Thus, an electromagnetic field is formed in the cavity between the electrically conductive tube 3 and the terminal 4, the parameters of which have a maximum value at the opposite end of the screen 7 from the point where the rod is connected to the RF generator. In a segment of the resulting long line (electrically conductive rod), oscillations of a quarter wavelength occur. In this case, the input impedance, which is a function of coordinates and having a reactive character, in a section that is a multiple of a quarter of the wavelength, has the value O or Sche, which determines the resonant nature of the meter operation. The propagation of electromagnetic oscillations along the length of tube 3, when the RF generator is connected to earth as a half-wave length of a long line, is identical (harmonically) to propagation in the strips between rod 4 and tube 3. In this case insignificant changes in the electrophysical properties of the contact {isolating syruds determine the changes in the resonant properties of the meter (output of the RF generator) by 50–60% higher than identical changes in the cavity between the rod 4 and the tube 3. O obuslavlivaets effect from the fact that as the conductor VChkolebany controlled environment is used, the electrical properties of which are measured. The choice of the cavity length between the open end of the electrically conductive rod 4 and the end of the tube 3 of the corresponding 1/4 dpi of the wave is caused by minimizing the dissipation of electromagnetic energy at the end of the sensing element, and, therefore, minimizing the effect on the output parameters of the external factor meter, i.e. the presence of electromagnetic interference, any structural links. An apparatus for measuring the density of dielectric liquids, comprising a housing within which a sensitive element is located, a high-frequency generator and a recording device, characterized in that, in order to improve measurement accuracy, the sensitive element is designed as an electrically conductive rod electrically connected as a quarter-wave length lines with a high-frequency generator and a tube symmetrically located relative to the rod of electrically conductive material connected Next to the ground of the high-frequency generator as a half-wave segment of a long line, and outside the tube of electrically conductive material there is an additional identical tube electrically connected to a housing filled with a controlled medium, and the distance between the rod end and the inner tube corresponds to a quarter-wave segment of a long line, and at the ends of the outer tube electric screens installed. Sources of information taken into account in the examination 1. US patent, cl. 324/585 V (G 01, h, 27/04), 3626284, 1971. 2. Patent IT, cl. 324-585 C (G 01, h. 27/04), 3688188, 1972. 3. USSR author's certificate number 483350, cl. G 01 N 9/24, 1979 (prototype).