SU739349A1 - Device for measuring unsteady temperatures - Google Patents

Description

Airbreating refers to the area of temperature measurements. Devices for measuring non-stationary temperatures are known in which, in order to reduce the dynamic errors caused by the inertia of the thermoconverter used, the output of the thermoconverter is corrected. Of the known devices for measuring non-stationary temperatures, the closest to the invention in its technical essence is a device for measuring non-stationary temperatures, which contains a frequency thermal converter, the output of which is connected to first generators by inputs of two reference frequency circuits connected to a counting trigger, single and zero. the moves of which are connected separately by reversing to the second inputs a circuit pulse counter with a digital indication unit and a one-shot included between the zero output of the trigger and the installation input of the reversing counter 3. The disadvantage of the device is the low accuracy of measurement of non-stationary temperatures due to the inertia of the frequency thermal converter. The aim of the invention is to improve the measurement accuracy. The goal is achieved by the fact that two frequency multipliers are provided in the device, the inputs of which are separately connected to the outputs of the AND circuits, and the outputs are connected respectively to the direct and inverse inputs of the reversible counter. The drawing shows the block diagram of the device. A device for measuring non-stationary temperatures contains a frequency converter 1, a reference frequency generator 2, a counting trigger 3, 4 and 5, a multiplier 6 two frequency circuits with a multiplication factor, a frequency multiplier 7 with a multiplication factor (22Г-1), one-shot 8, a reversible counter 9 and a digital display unit 10. The multiplication factor is 2Т 4TFci, where is the frequency of the reference oscillator, C is the indicator of thermal inertia of the thermal converter. The device works as follows. The output signal of the frequency converter 1 is fed to the first

and

4 and 5. On the inputs of two schemes

These inputs of the circuits 4 and 5 g alternately come in from the single and zero output of the counting trigger 3, which is triggered by the pulses of the reference frequency generator 2.

When a thermal shock is applied to a temperature jump, the output frequency f (t) of the thermal converter changes according to the law:

   -tfcf (t) fo + LP (1st),

where fp is the output frequency of the thermal converter 1 at the time of the impact of the temperature jump; dP is the increment of the output frequency caused by the effect of the temperature jump. After the end of the transient process, the output frequency of the thermocouple converter 1 is ff, + Ci.F.

Until the effect of the temperature jump on the inputs of the multipliers 6 and 7c of the output of the thermocouple generator 1

4 and 5 come in a series

cut circuit

pulses, the number of which in each series NO fp A.t is proportional to the measured temperature at a certain

the time span u.t, which is chosen to be 2Kt.

about

In this case, the direct and inverse inputs of the reversible counter 9 from the outputs of multipliers b and 7 receive pulses, the number of which in each series is equal to: 2jNc) and (2-2 - I) NQ. In counter 9, the process of calculating the pulse of impulses takes place, as a result of which the digital indicator is displayed in the digital display unit Yu, proportional to the measured stationary temperature:

& N 2fNj, - () NO N f t.

In the period of regular thermal conditions over a period of time db, the number of pulses N arriving at the inputs of multipliers 6 and 7 is determined by the relationship:

Af.

 I. f (t) dt. +

N.

o -, -, - (-,. 4., wC

+. -.- Cd-e) xdb (5o +,).

2 g

739349

The difference of pulses in the reversible counter 9 at this will be equal to:

LY 2rN | - (2tg -I) NO t (fo +

+ dR) Atf.

Consequently, already in time 5, the reversing counter 8 counts the number of pulses 4, N proportional to the f value of the output frequency converter 1, which is fixed by the digital display unit 10. from the zero output of the counting trigger 3, 5 The proposed device allows to reduce the time of measuring the temperature of non-stationary temperature process and thereby increase the measurement accuracy transient temperatures.

Claims (1)

Apparatus of the Invention A device for measuring non-stationary temperatures, comprising a frequency thermocouple, the output of which is connected to the first inputs of two circuits AND, a reference frequency generator connected to a counting trigger, whose single and zero outputs are connected separately to the second inputs AND , reversive counter 0 pulses with a digital display unit and a one-shot included between the zero trigger output and the reversible counter setup input, which is similar to that with 5 with the goal of increasing the measurement accuracy, two frequency multipliers are introduced into it, the inputs of which are separately connected to the outputs of the circuits I. And the outputs are connected respectively to the direct and 0 inverted reversible counter inputs. Sources of information taken into account in the examination 1, USSR Author's Certificate 384027, Cl, G 01 K 7/14, 1971, 2, USSR Author's Certificate No. 517812, class, G 01 K 7/14, 1974, 3, Golembo B, A ,, Boiler B, L. and Shvetsky B, I, Piezokhvartsvye analog-digital temperature converters, Lviv, Vishcha school, 1977, p. 146-156 - sheotype.