SU363048A1 - MEASUREMENT METHOD - Google Patents

Description

one

The invention relates to a measurement technique and can be used to increase the sensitivity of measuring devices with capacitive and inductive converters used to measure various non-electric quantities.

Known methods of measuring non-electrical quantities using capacitive and inductive sensors require quite complex measuring equipment, and they are also not accurate enough.

The purpose of the invention is to increase the resolution and simplify measuring instruments.

To do this, the frequencies of the electronic generator supplying converter and the tuning frequency of two resonant circuits, which are the load of this generator and switched on using the differential circuit, are simultaneously changed, and a voltage equal to the sum of two voltages occurs, one of which is proportional to the generator frequency change, and the other is the change in the tuning frequency of the resonant circuits.

The essence of the proposed method is illustrated in FIG. 1 and 2.

The electronic generator / has a frequency reference circuit consisting of inductance L and capacitance C, and a load in the form of differentially connected resonant circuits LjCi

and the latter of the OB-type or parallel type, from which the output voltage 17out is removed. The measured non-electric quantity 2 can simultaneously affect the elements of the frequency-setting circuit of the generator and the output circuits.

At the initial (zero) value of the measured non-electric quantity, the device generates with the nominal frequency fro, and the output resonant circuits are tuned to the frequencies foi and / o2, respectively, located on both sides of the frequency fro (see Fig. 2). In this case, the voltage on the resonant circuits is the same in magnitude and therefore the voltage across the load is zero.

Wow. 0).

A change in the non-electric value leads to a change in the generator frequency fr and the tuning frequency of the output resonant circuits (fi and / 2) so that when the frequency of the generator decreases by A /, the tuning frequency of each circuit increases by D / and, conversely, as the generator frequency increases by A / g, the tuning frequency of each loop to A / is reduced. The first case is shown in FIG. 2 dotted line.

As a result of the voltage inequality on the resonant circuits at the output, a voltage appears that is proportional to the change in the measured non-electric quantity and equal to the sum of the voltages, one of which AUr AUr + corresponds to the change in frequency Af, the generator, and the other A (7 to change the frequency Af settings of each resonant circuit (t / Bbis At / r-At /). The output voltage can be measured by known methods (for example, ic 1 using a frequency discriminator).

In order to implement the proposed method, it is necessary in the Inductive converter to change the non-electric value simultaneously cause a decrease (increase) in the inductance of the frequency generator and increase (decrease) the inductance of each resonant circuit, and in a capacitive converter the capacitor of the generator and output circuits should also change.

subject matter

A method of measuring non-electric values by capacitive and inductive converters, characterized in that, in order to increase the resolution and simplify measuring instruments, when measuring a non-electric quantity, the frequency of the electronic generator's supply converter and the tuning frequency of two generator resonators are simultaneously changed differential circuit, the voltage across the load being the sum of two voltages, one of which is proportional to eneniyu oscillator frequency, and the other - the change of resonance frequency tuning circuits.

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