SU1434415A1 - Temperature control apparatus - Google Patents

Abstract

The invention relates to a technique for automatic temperature control, and in particular to thermostatically controlled devices of chromatographs, and can be used in thermostatic devices of chromatographic columns, detectors, and sample input devices. The aim of the invention is to improve the accuracy. The device contains a thermostat 1, a heater 2, a thermostat temperature sensor 3., an amplifier 4, adders 5,8,10, controlled voltage dividers 6,16. setting unit 7, thermostat heat flow meter 9, control element 11, differentiating element 12, integrator-differentiator 13, integrating element 14, proportional element 15, network voltage amplitude converter 17, voltage-frequency converter 18, synchronizer 19, thyristor 20 Sensors 21-23, installed in the geometric centers of the walls on which there are no heat generating devices (detector, evaporator, engine), measure the temperature of the walls of the thermostat 1J, the signals of the sensors 21-23 are summed by the adder 27, at the output which produces a signal corresponding to the heat flux through the walls of thermostat 1, i.e. The division coefficient (thermostat transfer coefficient) will change in accordance with the change in the heat flux through the TepMoc-i-uTa walls, thus eliminating the influence on the accuracy of setting and maintaining the ambient temperature and heat transfer rate (blowing) of the outer walls of the thermostat. 1 hp f-ly, 1 ill. ,

Description

The invention relates to automatic temperature control, in particular, to temperature controlled devices of chromatographs, and can be used in devices for thermostating chromatographic columns of detectors and input devices.

The purpose of the invention is to improve accuracy. . .

The drawing shows the structural layout of the device.

The device contains a thermostat 1, in which a heater 2 and a thermostat 3 temperature sensor are connected, connected to the input of amplifier 4. The output of the latter is connected to the main input of the first adder 5, the output of which is connected to the input of the first controlled voltage divider 6, and the other input with the first output of the program setpoint 7 of the temperature at which a signal is formed that is proportional to the set temperature. The first output of the setting device 7 is also connected to the second input of the second adder 8, the first input of which is connected to the thermostat 9 heat flow meter, and the output to the first input of the third adder 10. The output of the summator 10 is connected to the control input of the first controlled divider 6, and the second input - with the second output of the setting device 7, on which

speed proportional signal

temperature programming. The second output of the setting device 7 is also connected to the control element 11, which controls the transfer coefficient of the differentiator integrator 12 differentiator 13, which includes differential differentiator 12 connected in parallel, integrator link 14 and proportional link 15. Integrator differential input - torus 13 is connected to the output of the first controlled divider 6, and the output is connected to the input of the second controlled voltage divider 16, whose control input is connected to the voltage amplitude converter 17 of the network, and the output to the inlet house the transducer 18 a voltage-frequency. The series is connected to the output of the synchronizer 19 and the entrance of the thyristor 20, through which the heater 2 is connected to the clamping network.

Thermostat 9 heat flow meter contains sensors installed on the outer walls of thermostat 1

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KI temperature 21, 22, 23, connected through large-scale amplifiers 24, 25, 26 with the inputs of the fourth adder 27.

The device works as follows.

A voltage proportional to a predetermined temperature is formed at the first output of the program setting device 7. This voltage is applied to the first input of the first adder 5, the second input of which supplies the opposite polarity, corresponding to the actual temperature of thermostat 1. This voltage is generated by amplifier 4, which converts the signal from thermostat 3 temperature sensor to a voltage proportional to the actual temperature. thermostat 1. At the output of the adder 5, an error signal is formed, proportional to the difference between the actual and set temperatures. The voltage proportional to the predetermined temperature from the first output of the setting device 7 is also supplied to the second input of the second adder 8, to the first input of which from the meter 9 the voltage of the opposite polarity is applied, which corresponds to the heat flow of the thermostat to the environment. At the output of the adder 8, a signal is generated that takes into account the heat flow of the thermostat to the environment. The signal from the output of the adder 8 is fed to the first input of the adder 10, the second input of which is supplied with a signal from the second output of the setter 7, proportional to the rate of temperature change. In the isothermal mode, the magnitude of the signal at the second input of the adder 10 is zero, therefore the signal at the output of the adder 10 is equal to the signal at its first input. From the output of the adder 10, the signal is fed to the control input of the controlled divider 6, to the signal input of which a signal is sent from the output of the adder 5. Changing the division factor of dividers 6 is equivalent to changing the transmission coefficient K of the temperature-controlled device.

The corrected error signal from the output of the controlled divider 6 is fed to the input of the integrator-differentiator 13, which implements the PID control law, i.e. integrating link 14 increases the stability of the control system (eliminates

move to the self-oscillatory mode), and differentiating link 12 partially compensates for the transport delays in the feedback circuit of the thermostat-

When operating in the temperature programming mode (speed range 1-24 ° C / min), with increasing programming speed, the magnitude of transport delays in the feedback circuit increases, resulting in a mismatch between the actual law of temperature variation and the specified one. In order to eliminate this inconsistency, the transmission coefficient of the differentiator of the link 12 of the integrator-differentiator 13 must be increased in proportion to the rate of temperature programming. This function is performed by the element P, to the input of which a signal is given that sets the rate of change, of the temperature from the second output of software setpoint 7.

The corrected error signal from the output of the integrator-differentiator 13 is fed to the input of the second controlled divider 16, the control input of which is connected to the output of the converter 17 of the supply voltage. At the output of the latter, a signal is generated, the value of which corresponds to the magnitude of the supply voltage. As the supply voltage changes, the split ratio of the controlled signal divider 16 also changes, which eliminates the influence of the supply voltage on the setting accuracy and temperature maintenance.

The signal from the output of the controlled delimiter 16 is fed to the input of the voltage-frequency converter 18, at the output of which a sequence of control pulses is formed, the number of which (frequency) is proportional to the signal output of the divider 16. The synchronizer 19 ensures that the thyristor turns on 20 at the beginning of the half-wave of the supply voltage of 22.0 V, 50 Hz and allows to reduce the value of switching currents when the valve 20 is turned on and the value of electromagnetic interference.

The value of 1 ,, .. ,,. in program mode oshis

Temperature control depends on programming speed. The higher the temperature programming speed, the greater the error signal, the mismatch between the set and the actual temperature.

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tour programs. This discrepancy is eliminated by changing the transfer coefficient of the thermostat proportional to the rate of temperature programming. For this purpose, the signal from the second output of the dial 7, corresponding to the temperature programming speed, is fed to the second input of the adder 10, the signal from the output of which is fed to the control input of the controlled divider 6, with which the transmission coefficient of the device is changed.

Sensors 21-23 installed in geometric centers of the walls on which there are no heat generating devices (detector, evaporator, engine) measure the temperature of the walls of thermostat 1, the signals of sensors 21-23 are summed by a third adder 27, the output of which produces a signal corresponding to heat flow through the walls of the thermostat 1, i.e. the magnitude of the division factor (thermostat transfer coefficient) will vary in accordance with the change in the heat flux through the thermostat walls, i.e. the influence on the accuracy of setting and maintaining the temperature of the ambient temperature and the intensity of heat exchange (blowing) of the external walls of the thermostat is excluded.

An advantage of the invention over a prototype is a significant increase in the accuracy of setting and maintaining temperature, reproducibility and accuracy of temperature programs, due to the elimination of transport delays between the change in the supply voltage and the response of the temperature-controlled device; the exclusion of the dependence of the accuracy of setting (reproducibility) of temperature on the magnitude of the supply, network voltage, maintained temperature and ambient temperature; excluding the effect on the accuracy of setting and maintaining the temperature, the intensity of heat exchange between the thermostat and the environment; maintaining the optimal value of the transfer coefficient of the thermostatic device in the whole range of supported temperatures and temperature programming speeds; maintaining the optimal value of the integrator-differentiator time constant throughout

temperature programming speed range; increase in the transmission coefficient of the thermostatic device.

Invention Formula

. A device for temperature control, containing a thermostat with a heater and a thermostat temperature sensor placed in it, in series with which the amplifier and the first adder 9 are a program temperature setpoint device. integrator-differential-15 controlled voltage divider, factorizer consisting of a parallel through which the output of the first summator second adder is connected to the first output of the temperature program control unit connected by the second output to one of the inputs of the third adder and the input of the control element connected by the output to the control to the input of the integrator-differentiator, another input of the second adder is connected to the output of the thermostat's heat flow meter, and the output of the second adder is connected to another input of the third adder, the output of which is connected to the control input of the first-controlled voltage divider, through which the output of the first summation of the second adder is connected to the first output of the programmable temperature setting device connected by the second output to one of the inputs of the third adder and the input of the control element connected to the output to the control input integrator-differentiator, another input of the second adder is connected to the output of the thermostat's heat flow meter, and the output of the second adder is connected to another input of the third adder, turn is connected to a control input of the first

but connected proportional, integral and differentiating links, serially connected voltage transformer and thyristor, as well as a synchronizer connected by an input to AC buses, and output to a control input of a voltage-frequency converter, a heater connected to the network AC through the thyristor, and the first output of the programmable temperature setting device is connected to another input of the first adder, about the fact that, for the purpose of accuracy, the device contains the second and the third adders, the first and second controlled voltage dividers, the thermostat heat flow meter, the control element and the network voltage amplitude converter1 (and the differentiator circuit of the integrator-differentiator unit is controllable, and one of the inputs

the torus is connected to the input of an integrator-differentiator connected via a second controlled voltage divider

with the input of the voltage-frequency converter, the amplitude converter of the network voltage is connected to the AC busbars, and the output to the control input of the second

controlled voltage divider.

2. The device according to A.1, about tl and - so that it has a meter of the Tegshov flow of the thermostat

contains temperature sensors, large-scale amplifiers for the number of temperature sensors and the fourth adder, and temperature sensors are installed on the outer walls of the thermostat

and through appropriate scale amplifiers are connected to the inputs of the adder, the output of which is connected to the output of the thermostat's heat flow meter.

Claims (2)

Formulas ^ inventions ^ 1. A device for controlling the temperature, comprising a thermostat with a heater and a temperature sensor located in it, in series with which an amplifier and a first adder _{9 are} included, a temperature programmer, an integrator-differentiator, consisting of parallel-connected proportional, integrating and differentiating units, connected in series a voltage-frequency converter and a thyristor, as well as a synchronizer connected by an input to the AC busbars, and an output to a control at the input of the voltage-frequency converter, the heater is connected to the AC network via a thyristor, and the first output of the temperature programmer is connected to another input of the first adder, which, in order to improve accuracy, the device contains the second and third adders, the first and the second controlled voltage dividers, thermostat heat flux meter, a control element and a voltage amplitude converter (the differentiating element, the integrator of the a-differentiator is made controlled, and one one of the inputs of the second adder is connected to the first output of the temperature programmer connected, the second output to one of the inputs of the third adder and the input of the control element connected to the control input of the integrator-differentiator, the other input of the second adder is connected to the output of the thermostat heat flow meter, and the output the second adder is connected to another input of the third adder, the output of which is connected to the control input of the first 15th controlled voltage divider, through which the output th adder is connected to the input of the integrator-differentiator connected via a second controllable voltage divider to the input of inverter 2a napryazheniechastota, the inverter voltage amplitude input is connected to the AC current buses, and output - to the control input of the second voltage divider 25 managed. 2. The device according to claim 1, characterized in that the heat flow meter of the thermostat 30 contains temperature sensors, scale amplifiers according to the number of temperature sensors and a fourth adder, the temperature sensors being installed on the outer walls of the thermostat __ and connected to the inputs through the corresponding scale amplifiers the adder, the output of which is connected to the output of the heat flow meter of the thermostat.