SU1229596A1 - Device for measuring temperature - Google Patents

Abstract

This invention relates to thermometry and can be used to measure the temperature of molten iron. The purpose of the invention is to improve the accuracy of temperature measurement. The device contains a thermal converter 1, an amplifier 2, a threshold element 3, blocks 4 and 5 time intervals, keys 6 and 7, a calculation unit 8, a display unit 9. A synchronization block 11 and a key 10 are also introduced into the device. The introduction of new elements and the formation of new connections between the elements of the device reduce the measurement error caused by a change in the heat exchange conditions of the thermal converter 1 when it is introduced into the measured medium, as well as by the effect of electrical noise. 3 il. from "CL with ND to CO SP JV with Od Fig, 1

Description

This invention relates to thermometry and can be used to measure the temperature of molten iron.

The purpose of the invention is to improve the measurement accuracy by reducing the measurement error caused by a change in the heat exchange conditions of the thermal agent when it is introduced into the measured medium, as well as by the effect of electrical noise.

FIG. 1 shows the functional diagram of the device in FIG. 2 shows the dependence of the output signal of the thermal converter on time; FIG. 3 is a scheme for measuring temperature.

The device for temperature measurement contains a thermocouple device 1, an amplifier 2, a threshold element 3, blocks 4 and 5 time intervals, first 6 and second 7 keys, calculation block 8, indication block 9, third key 10, and synchronization block 11. The device works as follows.

When measuring the temperature of the molten metal (cast iron), the thermocouple is first placed in hot air around the metal (region I, fig. 3), then in the slag (region II), and then in the molten metal (region III). In areas I-III, the increase in readings is carried out with different time constants t due to changes in heat exchange conditions in different environments, therefore the thermal emf of the thermal converter E (t) varies in accordance with the dependence represented on the graph. 2

When the origin of the point intersects the point (Ep,, t, 2), the voltage at the output of the thermal converter changes on the exponential dependence

E (t) (E-E -,) (1-e

- (tt ,,) / t.

cm

)

(one)

where E - thermo-emf is appropriate

the final value of the measured temperature; Ep, - thermo-emf at the moment t ,, t - current time, - constant of time of the thermal converter.

In order for the measurements to be carried out in region III, after the moment t / lowering the thermocouple into the metal, the threshold element 3 has a threshold #, which exceeds the value of ER. itycTb randomly selected

229596. 2

The threshold is triggered and the threshold device is triggered at a time that does not coincide with the time of zero crossing of the mains voltage. Then, after the element 3 triggers, the synchronization unit raises the signal to time blocks 4 and 5 and the third key 10 at time t, the transition through the zero of the network on the 110th strand. When this is done, the third key 10 receives a voltage at the input of the computing unit 8 at the instant tj, the output from the amplifier 2 is outputted in the block 8

 5 Е, Ер, + (Е-ЕО,) ()) (2)

at time t, blocks 4 and 5 time slots are also started. By the time t, a multiple of half a period

20 of the voltage of the network noise (Fig. 2), the signal at the output of the block 4 time intervals opens the key 6 and the output voltage of the amplifier 2 arrives at the input of the calculation block 8. Therefore, the countdown is fixed in the block 8

Е Е -КЕ-Е ,,) () (з)

si

01

At the instant tj of zero crossing of the network voltage, the output signal 2Q of the block 5 time intervals opens the key 7 and in block 8 the countdown is fixed

, + (Е-Е „,) () (4)

When condition (t) 2 (t, - tj2.) J is satisfied, which is achieved by appropriate adjustment of the VALUE PARAMETERS of blocks 4 and 5 time intervals, from the system of equations (2) (4) it follows that

E E - E. Ee

(five)

2E2-E, -E5

The calculation unit 8, as a co-Topofo, any device that provides a calculation using the specified formula, such as a microcalculator, can be used to determine the value of E (t) and, accordingly, the temperature of the melted metal.

As follows from expression (5), the result of the measurement E (t) does not depend on the value of Eg, the initial level, the threshold for triggering Ef, as well as the interference causing premature triggering of the threshold unit.

Claims (1)

Invention Formula A temperature measuring device containing a thermal converter connected via an amplifier to a threshold element, two time interval blocks, the first inputs of which are connected by means of each other, and the outputs are connected to the control inputs of two switches, the signal inputs of which are connected to the code of the amplifier, and the outputs are connected to the inputs calculation unit, the output of which is connected to the display unit, which is so that, in order to improve the measurement accuracy by 29596 reduction of measurement error caused by changes in heat exchange conditions thermocoupling when it is introduced into the measured medium, 5 a synchronization unit and a third key are entered in it, the signal input of which is connected to the amplifier output, the output is connected to the input of the calculator, and the control input is connected to the control the inputs of the time interval blocks and the output of the synchronization block, the first input of which is connected to the output of the threshold element, and the second input is connected to the second inputs of the time interval blocks AND the source of evogo voltage. ten 15 ff / f fs / g iBoySyx iU / ta / f  Roslladlm / fA / V VtftyH 9.9 Compiled by V. Kulikov Editor V. Petrash Tehred N. Bonkalo Proofreader T, Kolb Order 2444/41 Edition 778 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4