SU754377A1 - Temperature stabilizing device - Google Patents

Description

The invention relates to temperature control systems with automatic regulators with auxiliary ·, thermostats.

Thermostating devices are known that contain a thermostatic chamber formed by an isothermal shell with a heater and a thermistor placed on it, an insulating and outer protective shell, as well as an amplifier whose input is connected to a thermistor and output to a heater [1].

The disadvantages of the known thermostatic devices are low speed, the presence of a temperature error associated with a change in ambient temperature, increased power consumption during the transient process.

Known designs thermostatic devices contain a thermistor that measures the temperature of an isothermal shell or thermostatted object. Thus, these structures allow the thermostat to be controlled, as an object of regulation, only in one phase coordinate - the temperature of the isothermal shell or thermostatted object, and this is yn2

Management may not be optimal. For optimal control, you need measurement information on all phase coordinates of the thermostat.

The closest in technical essence is a thermostatic device containing a thermostatically controlled chamber, an isothermal, thermal insulation shell, a heater, an amplifier, thermistors and a regulator p).

This device, along with the main measuring thermistor located on the isothermal shell, uses an additional thermistor placed in the thickness of the heat insulating shell. However, this device, without providing a measurement of all phase coordinates of a thermostat, does not allow for the reliability of optimal control of it - and, therefore, it preserves all the disadvantages listed above.

The aim of the invention is to increase the speed and increase the accuracy of the thermostatic device.

The goal is achieved by

that the thermistors are located in a thermoelectric chamber, between the isothermal and heat-insulating shells,

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between the insulating sheath and the housing and on the outer surface of the housing.

The following heat fluxes act in the thermostatic device: () ₀₁ ~ from the external environment through the protective sheath to the heat insulating shell

Pos ^- from the external environment through the protective and insulating shells to the isothermal shell, etc. Each of these heat fluxes is proportional to the corresponding temperature difference:

=. (t) - T}); ί> ο, 1,2,3;

where K ΐ] is the corresponding thermal

conductivity

The described heat transfer scheme allows one to write down the differential equations of the thermostatting dynamics

go devices as: Si a (h η = -k ₁₀ (t,. - t _e ); υ -k ₍₂ (t, - t ₂ ) ¹ " ^ 22 χ (τ ₂ ^t ? (T ₂ "- tr + p; Thats ) - ^to 2, (T ₄ - T <) ¹ -RgzH (Of <t _and B ⁼ '" ^P ' E0 < ^t z" Tr y That) -K ₃ , (t ₃ t,) Where g g integral heat-

capacity;

p is the power released in the heater. The dot on the top denotes time differentiation.

As can be seen, the introduced system of thermistors makes it possible to measure all phase coordinates T (, T _g , T _e , which determine the dynamics of the thermostating device, that is, ensures complete observability of the thermostatic device as a control object, which is a necessary condition for the synthesis of optimal control.

The drawing shows a General view of the thermostatic device.

The thermostatic device contains a thermostatted chamber 1 formed by an isothermal shell 2, in which a thermostatted object is located (not shown in the drawing). On the outer side of the isothermal shell 2 is placed the heater 3. The chamber 1, the isothermal shell 2, the heater 3 are covered by the insulating shell 4 and the protective sheath (housing) 5.

A thermistor b is located on the inner surface of the isothermal shell 2, which borders on the object to be temperature-controlled. Thermistor 7 is placed between the isothermal shell 2 and the heat insulation shell 4, thermistor 8 between the thermal insulation shell 4 and the protective shell 5, thermistor 9 on the outer shell. surface of the protective shell. Thermistors 6, 7, 8, 9 are electrically connected to the input, and heater 3 is connected to the output of the (optimal) regulator 10.

Thermostatic device pa-. bots as follows.

After turning on the thermostatic device, a non-stationary temperature field is formed in it.

In this case, the thermistor 9 measures the temperature T _o at the boundary between the protective sheath and the environment, the thermistor 8 measures the temperature T _£ at the boundary between the protective and thermally insulated shells, thermistor 7 -. temperature T ₂ at the boundary between the heat insulating and isothermal shells, thermistor b is the temperature T ₃ at the boundary between the isothermal shell and the object being thermostatted. The measured values of temperature T _about , T | , T ₂ · -, T _e are used to form the control power of the heater P - optimal according to the selected criterion.

Optimal control is possible due to the fact that the system of thermistors 6,7,8,9 measures, in addition to the ambient temperature, all the phase coordinates of the thermostating device.

Claims (1)

Claim A thermostatic device containing a thermostatted chamber with isothermal and heat-insulating shells placed in the housing, a controller with thermistors connected to its inputs, and a heater to the output, characterized in that, in order to increase speed and increase the accuracy of the device, thermistors are placed; in a thermostatically controlled chamber, between - “isothermal and heat insulating shells, between the heat insulating sheath and the body and on the outer surface of the body.