JPS59191622A - Temperature controller - Google Patents

Abstract

PURPOSE:To eliminate both overshoot and undershoot which are generated by the intermittent operation of a refrigerator and to attain the smooth temperature control, by applying different levels of electric power to be applied to a heater between the start and stop modes of a refrigerator. CONSTITUTION:A thermostatic chamber consists of a prefabricated chamber 1, heaters 3-1-3-3 set in the chamber 1, refrigerators 4 and 5, etc. When the refrigerators 4 and 5 are actuated, the heaters 3-1-3-3 are energized. While the heater 3-2 or 3-3 is energized when the refrigerator 4 or 5 is stopped. As a result, a sudden reverse temperature change is produced to eliminate both overshoot and undershoot which are produced by the intermittent operation of the refrigerator. Thus the smooth temperature control is made possible.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a temperature control system for a thermostatic chamber or thermostatic chamber;
In particular, it relates to the open side 1 method such as temperature rise and fall.

[Prior art]

In addition to keeping the temperature constant in a thermostatic chamber or thermostatic bath, ie, a constant temperature state, there may also be a need for the ability to change the temperature from one temperature to another at a constant rate. A typical thermostatic chamber or bath is equipped with a low heat source, such as a refrigerator, and a high heat source, such as an electric heater. Refrigerators are used with binary control (ON10FF control) due to their essential characteristics,
Electric heaters are commonly used with continuous control.

The amount of heat required in the chamber (or tank) at a given time is obtained by compensating the amount of heat absorbed by the refrigerator with an electric heater. When the amount of heat from the electric heater is insufficient, the operation of the refrigerator is stopped and the required amount of heat is provided only by the electric heater.

In other words, under constant temperature conditions, the refrigeration machine and electric heater are operated,
A constant temperature is maintained by continuously controlling the electric heater, but as the temperature rises, a much larger amount of heat is required, so the refrigerator is stopped and controlled only by the electric heater.

By the way, when switching from constant temperature conditions to temperature increase conditions,
Because the thermal time constant of the room (oak) and the time constant of the control system cannot completely match, the actual temperature (actual value) of the room (tank) becomes too high than the set value, so-called overflow. Shoots may occur. If the temperature increase condition is continued as it is, the overshoot will eventually be cured, but since the distinction between constant temperature condition and temperature increase condition is judged by comparing the actual value and the set value, once the temperature increase condition Even if it does, the temperature will return to the IF temperature condition at the point of overshoot, and the refrigerator will operate, causing undershoot.

As a result, overshoot and undershoot are repeated alternately, and a situation often occurs in which smooth temperature control becomes difficult. Such a phenomenon occurs not only in a temperature rising region but also under warm adhesive conditions. The root cause of this phenomenon is a thermostatic chamber (tank)
This is due to overshoot and undershoot caused by the difference in thermal time constant between the control system and the control system.

[Purpose of the invention]

The present invention was invented in view of the above, and solves the above-mentioned problems of temperature control systems, and allows smooth operation of the chamber (tank) that is faithful to the set value.
The purpose is to provide a control method that can realize temperature control.

[Summary of the invention]

In order to achieve the above object, the present invention provides a first maximum input power to the heater when the refrigerator is started, and a second maximum input power to the heater that is lower than the first input power when the refrigerator is stopped. It is characterized by intentionally generating a rapid temperature change in the opposite direction to counteract the overshoot and undershoot that occur due to intermittent operation of the refrigerator.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. The figure shows a constant temperature room, which includes a prefabricated room 1, a blower 2, a heater 3, a refrigerator 4.5, and a cooler 6.7, which are connected to each other by refrigerant piping. It consists of The temperature in the room is detected by a sensor 8, and its value is compared with the output setting value of a temperature setting device 10 by a temperature controller 9. The comparison result is given to the power regulator 11, and the amount of power supplied from the power source 12 to the heater 3 is adjusted. Furthermore, the subtraction circuit 13 calculates the difference from the room temperature set value, and based on the result, the three heaters 3a, 3b are
, 3c, and the two refrigerators 4.5 to be driven. FIG. 2 is a diagram illustrating the operating status of each device in each mode of temperature rise and constant temperature/fall. Moreover, FIG. 3 is a diagram showing the operation timing of each device for each mode. The operation timing of the refrigerator and heater will be explained in detail below with reference to each figure.

The refrigerator 4 and heaters 3a and 3b operate in a constant temperature state.

The electric power applied to the two heaters is controlled by a power regulator 11 to balance the cooling heat amount of the refrigerator 4.

(c) As the set value (broken line) increases, heaters 3a and 3b
However, the two heaters 3a and 3b cannot compensate for the cooling heat amount of the refrigerator 4, and the difference between the set value and the room temperature (solid line) gradually increases at time 1. △1
If it exceeds ゛1, freezing @4 will stop. The overshoot that occurs at this time becomes large enough to return to a constant temperature state (dotted chain line), but at the same time, by stopping the heater 3b, the geo-overshoot is reduced to a small value as shown by the solid line.

0 When transitioning from a temperature increase condition to a constant temperature condition -4= (time "2"), conversely, the refrigerator 4 operates and the heater 3b is energized to prevent excessive undershoot.

0 Under the temperature drop condition, at the time t3 when the difference between the set value and the room temperature becomes 1△T2, in addition to the refrigerator 4, 5 is activated, and at the same time, the heater 3C is also energized, so the undershoot is as shown by the dashed line in the diagram. becomes smaller as shown by the solid line.

In short, the present invention simultaneously eliminates the undershoot and overshoot caused by ON-OF'F of the refrigerator. This can be resolved by turning the third heater on and off.

The unstable operation of overshoot and undershoot, which has been a problem in thermostatic chambers and thermostatic chambers, can be resolved, and the room (tank) temperature can be maintained smoothly and faithfully to the set value.

In the present invention, although the special case of two refrigerators has been explained in the embodiment, the present invention is not limited to this configuration, and various modifications are possible.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a constant temperature room showing an embodiment of the present invention, Figure 2 is a diagram explaining the operating mode of the constant temperature room and the operating status of each device, and Figure 3 is the operation timing of each device in the constant temperature room. FIG. 1... Prefab room 2... Blower 3... Heater 4... First refrigerator b... Second refrigerator
6...First cooler 7...Second cooler
8...Sensor 9...Temperature controller 10...
Temperature setting device 11... Power controller 12... Power supply
13...Subtraction circuit = 71

Claims (1)

[Claims] A heater and a cooler attached to the refrigerator are installed in the room (tank), the refrigerator performs binary control operation, and the heater performs continuous control operation to maintain the room (tank) at the desired temperature. In a constant temperature room (tank) where the refrigerator is started, the first maximum input power is given to the heater, and when the refrigerator is stopped, the second input power, which is lower than the first input power, is given to the heater. A temperature control device for a thermostatic chamber (tank) characterized by the following.