SU979891A1

SU979891A1 - Device for measuring temperature

Info

Publication number: SU979891A1
Application number: SU813244340A
Authority: SU
Inventors: Сергей Гаврилович Булыга; Николай Иванович Грибок; Владимир Иванович Зорий; Роман Николаевич Огирко; Владимир Иванович Пуцыло; Василий Александрович Яцук; Евгений Иванович Шморгун; Владимир Богданович Здеб
Original assignee: Львовский Ордена Ленина Политехнический Институт Им.Ленинского Комсомола
Priority date: 1981-02-05
Filing date: 1981-02-05
Publication date: 1982-12-07

Description

(54) УСТРОЙСТВО ДЛЯ ИЗМЕРЕНИЯ ТЕМПЕРАТУРЫ(54) DEVICE FOR TEMPERATURE MEASUREMENT

1one

Изобретение относитс к области температурных измерений и может быть использовано при построении цифровых термометров с автоматической компенсацией термо-ЭДС свободных концов термоэлектрического преобразовател .The invention relates to the field of temperature measurements and can be used in the construction of digital thermometers with automatic compensation of the thermo-emf of the free ends of a thermoelectric converter.

Известно устройство дл измерени температуры, содержащее термоэлектрические преобразователи, подключенные через коммутатор к компенсационному мосту, включаюгпёму в себ термопреобразователь температуры свободных концов термоэлектрических преобразователей , измерительный блок и блок пам ти l.A device for temperature measurement is known, which contains thermoelectric converters connected through a switch to a compensation bridge, including a temperature transducer for the free ends of thermoelectric converters, a measuring unit and a memory unit l.

Однако это устройство не обеспечивает высокой точности измерени температуры .However, this device does not provide high accuracy temperature measurement.

Наиболее близким по технической сущности к изобретению вл етс устройство дл измерени температуры, содержащее термоэлектрический преобразователь , соединенный с первым вхо дом переключател и первым входом усилител , выход которого подключен к первому входу ключа, второй вход которого соединен с источником опорного напр жени , а выход через интегратор и нуль-орган подключен к входуThe closest to the technical essence of the invention is a temperature measuring device comprising a thermoelectric converter connected to the first input of the switch and the first input of the amplifier, the output of which is connected to the first input of the key, the second input of which is connected to the voltage source, and the output through the integrator and the zero-body is connected to the input

селектора, соединенного с генератором тактовых импульсов, две схемы ли-, неаризации, входы которых соединены с выходами селектора, первый реверсивный счетчигс, входы которого соединены с выходами первой схемы линеаризации , регистратор, термопреобразователь сопротивлени , подключенный через Преобразователь сопротив10 лени в напр жение к второму входу переключател , блок управлени , соединенный с управл ющими входами первой схемы линеаризации, переключател , ключа, нуль-органа и селекто 5 ра 2.the selector connected to the clock pulse generator, two linearization circuits, nonarization, the inputs of which are connected to the outputs of the selector, the first reversible counter, the inputs of which are connected to the outputs of the first linearization circuit, a recorder, a resistance thermocouple connected through a resistance converter 10 to the second the input of the switch, the control unit connected to the control inputs of the first linearization circuit, the switch, the key, the null organ and the selector 5 pa.

Однако известное устройство имеет недостаточно высокую точность измерени из-за вли ни на результат измерени ёходных дрейфов усилител However, the known device has an insufficiently high accuracy of measurement due to the effect on the measurement result of the amplifier’s drift.

20 посто нного тока, что требует дл повышени точности измерени приме- н ть сложные и дорогосто щие усилители . Кроме того, в известном устройстве возможна автоматическа компенсаци изменений температуры &с свободных концов только при б(,-7 0°С, что значительно сужает область его применени .20 dc, which requires complex and expensive amplifiers to improve measurement accuracy. In addition, in the known device, it is possible to automatically compensate for changes in temperature & from the free ends only at b (, - 7 0 ° C, which significantly narrows the scope of its application.

Целью изобретени вл етс повы30 шение точности измерени .The aim of the invention is to improve the measurement accuracy.

Поставленна цель достигаетс тем, что в устройство введены две 1схемы ИЛИ, источник напр жени смещени и второй реверсивный счетчик, входы которого соединены с выходами схем ИЛИ, а выходы соединены с регистратором и блоком управлени , соединенным с управл ющим входом второй схемы линеаризации, причем входы первой схемы ИЛИ соединены с выходамипервой и второй схем линеаризации , входы второй схемы ИЛИ соединены с выходами первой схемы линеаризации, а источник напр жени смещени включен между выходом переключател и вторым входом усилител , первый вход которого соединен с третьим входом переключател .The goal is achieved by introducing two 1 OR circuits, a bias voltage source and a second reversible counter, the inputs of which are connected to the outputs of the OR circuits, and the outputs connected to the recorder and the control unit connected to the control input of the second linearization circuit, and the inputs the first OR circuit is connected to the outputs of the first and second linearization circuits, the inputs of the second OR circuit are connected to the outputs of the first linearization circuit, and the source of the bias voltage is connected between the output of the switch and the second input of the istel, the first input of which is connected to the third input of the switch.

На чертеже приведена блок-схема устройства.The drawing shows a block diagram of the device.

Устройство содержит термоэлектрический термометр 1, переключатель 2, усилитель 3, источник напр жени смещени 4, ключ 5, интегратор б, нуль-орган 7, источник опорного напр жени 8, генератор тактовых импульсов 9, селектор 10, регистратор - цифровое отсчетное устройство 11, первый реверсивный счетчик 12, первую схему ИЛИ 13, первую и вторую схемы линеаризации 14 и 15, вторую схему ИЛИ 16, второй реверсивный счетчик 17, термопреобразователь сопротивлени 18, преобразователь сопротивлени в напр жение 19, блок управлени 20.The device contains a thermoelectric thermometer 1, switch 2, amplifier 3, bias voltage source 4, switch 5, integrator b, null organ 7, voltage source 8, clock generator 9, selector 10, recorder - digital reading device 11, the first reversible counter 12, the first OR circuit 13, the first and second linearization circuits 14 and 15, the second circuit OR 16, the second reversible counter 17, a thermal resistance converter 18, a resistance converter to voltage 19, a control unit 20.

Устройство работает следующим образом .The device works as follows.

В первом такте при включении устройства по сигналу с блока управлени переключатель 2 подключает к вхо ду усилител 3 источник напр жени смещени 4, ключ 5 подключает к входу интегратора выход усилител 3, селектор 10 закрываетс , а все остальные элементы устройства перевод тс в исходное состо ние. При этом на вход интегратора поступает напр жениеIn the first cycle, when the device is turned on by a signal from the control unit, switch 2 connects to the input of amplifier 3 an offset voltage source 4, switch 5 connects the output of amplifier 3 to the integrator input, selector 10 closes, and all other elements of the device are reset. . In this case, the input voltage of the integrator

U,--K,,(UcwtUo),U, - K ,, (UcwtUo),

И)AND)

где Ко - коэффициент усилени усилител ;where Ko is the gain of the amplifier;

и, - выходное напр жение источника смещени 4 и - напр жение входного дрейфаand, - the output voltage of the bias source 4 and - the input drift voltage

усилител ,amplifier,

которое интегрируетс в течение интервала времени Т, длительность которого выбираетс равной периоду напр жени сети питани устройства и задаетс блоком управлени 20. Напр жение смещени , всегда выбираетс большим максимально возможного значени дрейфа.и, так что U всегда больше нул .which is integrated over a time interval T, the duration of which is chosen equal to the voltage period of the supply network of the device and is set by the control unit 20. The bias voltage is always chosen as large as possible and so that U is always greater than zero.

В конце интервала времени Т на вы ходе интегратора возникает напр жениеAt the end of the time interval T, during the course of the integrator, a voltage arises

UH. К„ ; и dt (,)-T,(2) Uh K „; and dt (,) - T, (2)

где К - , ( t; - посто нна времени интегрировани интегратора). После окончани интервала времени т по сигналам с блока управлени ключ 5 подключает к входу усилител выход источника опорного напр жени 8, селектор 10 откарываетс дл прохождени импульсов от генератора тактовых импульсов 9 на входwhere K -, (t; - constant of integrator integration time). After the end of the interval of time t according to signals from the control unit, the key 5 connects to the input of the amplifier the output of the source of the reference voltage 8, the selector 10 opens up to pass pulses from the generator of clock pulses 9 to the input

первой схемы линеаризации 14 С приthe first linearization scheme 14 With

этом устанавливаетс посто нный коэффициент преобразовани последней, а с ее выхода на вычитающий вход первого реверсивного счетчика импульсов 12 и через вторую схему ИЛИ 16 на вычитающий вход второго реверсивного счетчика импульсов. 17.this sets the constant conversion coefficient of the latter, and from its output to the subtracting input of the first reversible pulse counter 12 and through the second OR circuit 16 to the subtracting input of the second reversible pulse counter. 17

Напр жение Uj, с выхода источника опорного напр жени 8 интегрируетс вThe voltage Uj from the output of the voltage source 8 is integrated into

тече15ие интервала времени t до тех пор, пока интегратор б не возвратит в исходное состо ние, т.е. пока не будет выполнено условиеthe time interval t until the integrator b returns to the initial state, i.e. until the condition is met

.%UH-- h|Vt-- HUot, сз;.% UH-- h | Vt-- HUot, cz;

Длительность интервала t определ етс выражением, получемым из (3) и(2)The duration of the interval t is determined by the expression derived from (3) and (2)

.. K4(UcM t Ug)- Т.. K4 (UcM t Ug) - T

(4)(four)

иand

Момент окончани интервала t фиксируетс нуль-органом 7. По-его сигналу селектор 10 закрываетс . При этом в реверсивных счетчиках зафиксируетс код числа N, равныйThe moment of the end of the interval t is fixed by the null organ 7. By its signal, the selector 10 is closed. At the same time, the code of the number N equal to

KV(UCAA 1 Ufl)TKV (UCAA 1 Ufl) T

(5)(five)

N f . t f -,..N f. t f - ..

Tо To

где f - частота импульсов генератора тактовых импульсов 9.where f is the pulse frequency of the clock pulse generator 9.

Во втором такте по сигналу с блока управлени переключатель 2 подключает к входу усилител 3 через источник напр жени смещени 4 выход преобраэовател сопротивлени в напр жение 19, а ключ 5 подключает к входу интегратора б выход усилител 3.In the second cycle, according to the signal from the control unit, switch 2 connects to the input of amplifier 3 through the bias voltage source 4 the output of the resistance converter to voltage 19, and the switch 5 connects to the integrator input b the output of amplifier 3.

При этом на вход интегратора б поступает напр жениеIn this case, the input of the integrator b receives the voltage

.VSUUcMtU9), (6).VSUUcMtU9), (6)

где и -напр жение на выходе прес образовател сопротивлени where and is the voltage at the output of the compress formative resistor

в напр жение 19; к - коэффициент преобразовани at voltage 19; k - conversion factor

Claims

converter 19; - change in the resistance of the thermocouple with the change in temperature fi of the free ends of thermoelectric converter 1; R is the resistance of the thermal converter when. Moreover, the value of U. is chosen so that it is greater than zero. The voltage and,.., Is integrated by the integrator during the time interval T, at the end of which the voltage tUH K & T and -dt K {and 1 and) 1 ± UejT arises at the integrator output. On the other hand, 9 (After the end of the time interval T according to signals from the control unit, the key 5 connects to the integrator input a voltage source, and the selector 10 opens for the passage of pulses from the clock pulse generator to the input of the first linearization cxeNM 14 constant transform coefficient last), and from its output to the summing input of the reversible counter 17. The voltage Up from the output of the source of the reference voltage 8 is integrated during the time interval t until integrator 6 returns to the initial state, i.e., until the condition v, Jv, a К „/ 8 is fulfilled. The duration of the time interval is determined by the expression fK KUcrw U) -i Ugc Moreover, if c 0 ° C, then tt, a as . In the first case, at the moment when the interval ends -t 2. nullorgan 7 is triggered and, by its output signal, the control unit gives a command to connect the output of the first linearization scheme via the second OR 1 circuit to the subtractive counter 17 and set the output of the variable (functional) conversion factor circuits 14. In this case, the subtracting input of the counter 17 from the output of the linearization circuit 14 through the circuit OR 16 receives pulses of variable frequency f, and the summing input of counter 12 continues to flow AND; pulses of a constant frequency f The transfer point of the counter 12 through zero, i.e. the arrival of N pulses, the selector 10 is closed, stopping the supply of pulses to the second input of the linearization circuit 14. During the time interval, the N input and the radius arrive at the next input 17 of the counter 17)) As a result of two conversion cycles at t2 t, the code 17 will be fixed in the counter 17 NN + N numbers. (u. and,) +) In the second case, when t ri 7 t, the pulses of frequency t arrive at the summing input of counter 12 until the moment t of its transition to zero zero. the moment of transition the control unit gives the command to connect the output of the linearization circuit 14 through the circuit OR 13 to the summing input of counter 17 and to set the variable (functional) conversion coefficient of the linear loop on this output 14. At the same time, the variable frequency pulses f from the output of the circuit OR 13 arrive at summing the input of the counter 17 from time t to the moment. when the zero-body 7 operates, the signal of which closes the selector 10. The totalizing input of counter 12 receives N pulses 2.)) as a result of two conversion cycles at 7 t, the code of number NN will be fixed in counter 17, - N , -1o. i and „) in the third cycle, according to the signal from the control unit, the selector 10 closes, switch 2 connects to the amplifier 3 through a bias voltage source 4 OUT of the thermoelectric thermometer. In this case, the input voltage of the integrator b is (Qx, Qc) + (cm -t 9), (14) where ElQy.Q) is the output thermo-EMF of the thermoelectric thermometer at a variable temperature QX of its working spa and temperature QC its non-working junctions. The value of E (n, y, Qg) can be represented in the form of Her © x, gs) - E (ex, 0). ± DE (о, 5с), (гдЬ) ((1, О) - thermo-EMF of a thermoelectric thermometer 1 at the temperature of the free ends, corresponding to the values at which the thermoelectric converter is graduated; Е (0, Р)) correction and thermoelectric The EMF of a thermoelectric converter when the temperature of the free ends of the QP differs from 0 ° C, and if ((-., Then in expression (15) there is a minus sign, and if 0 then it is plus. Voltage (Ji is integrated by integrator 6 during the time interval , at the moment of the end of which, at the output of the integrator, a voltage yjn J –c K - to HU occurs (PU, Qc MS T. (16 (Uy After the end of the time interval T, the output of the reference voltage source 8 is connected to the input of the integrator), the selector 10 opens for the passage of 5o pulses from the clock generator 9 to the input of the digital linearization circuit 15 (this sets the constant coefficient the last one), and from its output to the cyrm input of the reversing pulse counter 17. The voltage 1 / from the output of the reference voltage source is integrated during the time interval ij D ° as long as the integrator b returns to the initial state, i.e. until the condition, 1, / Ч d ,, (17 Duration of the time interval -tj, is determined by the expression -Ka E (QX, 0) i DE (0, QC) + (UcM + Ug) 3 T / S- Pulses of frequency t f, from the output of the clock pulse generator come through a linearization circuit of 15 ° C with its constant conversion factor) to the summing input of the pulse counter 17 during the time interval until the moment of zero crossing of the reversible counter 17 V a variable (functional) conversion coefficient of the linearization scheme is established 15. From the last output, the variable frequency pulses go to the summing input of counter 17 until the end of the time interval-t., I.e. until the zero-organ 7 is triggered, by a signal from which the control unit closes the selector 10. At the same time, in the counter 17, N pulses will be fixed in time t - t, where t is U., q is Q or T: 7 ° C. Using the expressions for t and -t, we obtain, T When the condition At (0, Qc,) is fulfilled, THAT is easy to accomplish by means of a functional change in the conversion coefficient of the linearization circuit 1.4, based on the given calibration characteristic DE (Qj ,, 0) of the thermoelectric converter 1 (by functional change of frequency f,), we obtain .. By providing fj Е ((1,0) Q by functional. changing the conversion factor of the linearization circuit 15, based on the given calibration characteristic, E (Qx, 0) of the thermoelectric converter, by measuring N, not depending on changes in the temperature of the free ends Q, i.e. KQ, where K is a constant coefficient depending on the parameters of the device, introducing new elements and new connections into the device, as well as changing its operation algorithm improves the accuracy of temperature measurement, since automatic compensation of changes in the thermo-emf of a thermoelectric converter caused by changes in the temperature of its free ends is carried out numerically after analog-digital transformations, and therefore does not require, as in the known device, the formation of low levels of compensating voltages at the input, which reduces the accuracy and noise immunity of measurements. In addition, the device eliminates the effect on the measurement result of the input drifts of the dc amplifier. The invention The device for measuring temperature, containing a thermoelectric converter connected to the first input of the switch and the first input of the amplifier, the output of which is connected to the first input of the key whose second input is connected to the reference voltage source, and the output through the integrator and the zero-organ is connected to the input of the selector connected to the clock pulse generator, two linearization circuits, the inputs of which are connected to the outputs of the selector, the first reversible counter of the VC1ODY of which is connected to the outputs of ne drive of linearization circuit, recorder, thermal converter of resistance, connected through converter of resistance to voltage to the second input of the switch, block