JPH04373006A - Temperature increase/decrease control method - Google Patents

Abstract

PURPOSE:To automatically, precisely and smoothly increase or decrease the inside temperature of a tank without setting the active/inactive or switching state of cooling ability each time the temperature is increased/decreased to a target set temperature at a desired temperature change rate. CONSTITUTION:In the case of changing the inside temperature of a tank 1 to the target set temperature higher than a current temperature, the temperature is controlled by stopping a freezer 3 and controlling a heater 2 when difference between the set temperature and the current temperature is higher than a value decided in advance and the desired temperature change rate is higher than a predictive value. In the other case, the temperature is controlled by controlling the heater 2 while keeping the current active or inactive state of the freezer 3. In the case of changing the inside temperature of the tank to the target set temperature lower than the current temperature, the freezer 3 is operated when the difference between the set temperature and the current temperature is lower than the predictive value and the desired temperature change rate is higher than the value decided in advance, the cooling ability is increased when the freezer is already under operating, and the heater 2 is controlled. In the other case, the temperature is controlled by controlling the heater 2 while keeping the current inactive or active state of the freezer 3.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a constant temperature bath and a constant temperature bath used to expose various materials and parts of various equipment to predetermined temperature cycles and examine their thermal stress characteristics, durability, thermal strength, etc. This paper relates to a method for controlling temperature rise and fall in an environmental testing device such as a humidity chamber.

0002

2. Description of the Related Art Conventionally, temperature rise and fall control within a tank in an environmental test apparatus or the like has been carried out as follows. That is, when increasing the temperature, depending on the difference between the current temperature in the tank and the target set temperature, if the difference is greater than a predetermined value, the cooling means is stopped or the heating capacity of the heating means is increased. When lowering the temperature, if the difference between the current temperature in the tank and the target set temperature is greater than or equal to a predetermined value, the cooling means is operated, or if it is already in operation, its cooling capacity is increased. .

Also known is a method of controlling temperature rise and fall by operating the heating means based on a PID time-division output signal and operating the cooling means in accordance with the inverted output of that signal.

0004

However, in the former method, the temperature is raised or lowered only in accordance with the amount of deviation of the target set temperature from the current temperature in the tank. Therefore, it is effective if the state in the middle of the temperature change before and after the target temperature setting is a step (stepwise) change, but if the temperature changes at a predetermined rate of temperature change (rate of temperature change per unit time) When attempting to lower the temperature, the amount of temperature deviation before and after the temperature control setting is smaller than that of a step change, so it is not possible to condition the operation of the heating means and cooling means using only the above-mentioned heating capacity and cooling capacity switching conditions. For gradient control, it is not possible to select the appropriate capacity of these means.

Furthermore, according to the latter method, since the cooling capacity constantly fluctuates, only rough control exceeding the allowable temperature adjustment range within the tank can be performed. SUMMARY OF THE INVENTION Therefore, the present invention aims to provide a temperature rise/fall control method that can accurately and smoothly raise or lower the temperature inside a tank to a target set temperature at a desired temperature change rate. be.

[0006]

[Means for Solving the Problems] In accordance with the above-mentioned object, the present invention is a temperature increase/decrease control method for raising or lowering the temperature inside a tank to a target set temperature at a desired temperature change rate. A heating means and a tank cooling means are prepared, and in order to change the temperature inside the tank to a target set temperature higher than the current temperature, the desired temperature change is achieved when the difference between the set temperature and the current temperature is a predetermined value or more. When the rate is above a predetermined value, the cooling means is stopped and the heating means is operated in a controlled manner to control the temperature rise; otherwise, the heating means is controlled with the cooling means being operated or stopped. When operating the tank to control temperature rise and change the temperature inside the tank to a target set temperature lower than the current temperature, the difference between the set temperature and the current temperature is a predetermined value or more, and the desired temperature change rate is set in advance. When the temperature exceeds a predetermined value, the cooling means is operated, and when it is already in operation, its cooling capacity is increased and the heating means is operated in a controlled manner to control the temperature drop, and when it is not, the cooling means is stopped. Alternatively, there is provided a temperature rise/drop control method characterized in that the temperature drop is controlled by controlling the heating means while the current state of operation is maintained.

[0007] The difference between the predetermined set temperature and the current temperature and the temperature change rate can be determined through preliminary experiments or the like.

[0008]

[Operation] According to the control method of the present invention, when the temperature inside the tank is increased to a target set temperature higher than the current temperature at a desired temperature change rate, the difference between the current temperature and the set temperature is greater than or equal to a predetermined value, and the change occurs. When the rate is equal to or higher than a predetermined value, the cooling means is stopped and only the heating means is used to increase the rate. When this is not the case, the heating means is controlled to raise the temperature while the cooling means is operating, or when stopped, it is stopped.

[0009] When lowering the temperature inside the tank to a target set temperature lower than the current temperature at a desired rate of temperature change, the difference between the current temperature and the set temperature is greater than or equal to a predetermined value, and the rate of change is greater than or equal to a predetermined value. In this case, if the cooling means is stopped, it is activated, and if it is already in operation, it is operated to increase its cooling capacity, and the heating means is also operated in a controlled manner. When this is not the case, the cooling means is left in its current state of operation or stoppage, and the heating means is controlled to lower the cooling means.

[0010] In both ascending control and descending control,
During ramp (gradient) control, the cooling capacity does not change and remains constant.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a device for carrying out the method of the invention. This device is a constant temperature chamber, which is a type of environmental testing device, and is equipped with a constant temperature chamber 1. The thermostatic chamber 1 can be opened and closed by a door 11, has a partition wall 12 at the back of the chamber, and has an air-conditioned room 13 behind it.

[0012] In the air conditioned room 13, a blowing fan 14, an electric heater 2, and a cooler 31 of the refrigerator 3 are arranged in order from top to bottom. A temperature sensor 4 for detecting the current temperature inside the tank is arranged at the air-conditioning room outlet 15. The air in the tank is circulated so that the temperature of the air in the air conditioned room is regulated by the operation of the fan 14, and the air is blown out from the air outlet 15 and sucked into the air conditioned room again through the suction port 16.

The refrigerator 3 is of a type already known per se and includes, in addition to the cooler 31 mentioned above, a compressor 32, a condenser 33 and an expansion valve 34. The expansion valve 34 is a so-called electronic expansion valve, and its opening degree is adjusted by a stepping motor 35. A temperature regulator 5 is provided outside the tank, and the operation of the heater 2, compressor 32, and motor 35 is controlled based on these instructions. The current temperature inside the tank from the temperature sensor 4 is always input to this. This regulator is provided with a panel 51 for inputting the target set temperature in the tank, the gradient of temperature rise or fall toward the set temperature (temperature change rate), and the like.

Further, the regulator 5 compares the set temperature with the current temperature inside the tank detected by the sensor 4, and further adjusts the temperature of the heater 2 by PID calculation according to the set temperature change rate in temperature rise and fall control. The system is configured to output a time-sharing proportional heating instruction signal for operation. Furthermore, the regulator 5
In temperature rise control, the difference between the current temperature in the tank and a higher target temperature is greater than or equal to a predetermined value PT1, and the desired rate of temperature change in temperature rise is a predetermined value (rate of change) PA1. In the above cases, the compressor 32 is stopped, and in other cases, the compressor 32 is configured to continue to operate, or to remain stopped if it is stopped.

Furthermore, in temperature drop control, the difference between the current temperature in the tank and a lower target set temperature is greater than or equal to a predetermined value PT2, and the desired rate of temperature change in temperature drop is a predetermined value ( When the rate of change) is PA2 or higher, the stopped compressor 32 is started, or if it is already in operation, the stepping motor 35 is used to increase the opening degree of the expansion valve 34 to increase the cooling capacity. Otherwise, the compressor 32 is configured to remain stopped, or to continue operating if it is already in operation.

[0016] In addition, the regulator 5 controls the heater 2 to maintain the controlled operation and the refrigerator 3 to the ambient temperature of the device during steady control (control to maintain the target constant temperature in the tank) that is not ramp (gradient) control. It is configured to operate or stop according to a predetermined program. Next, an example of the method of the present invention implemented in this thermostat will be described.

[0017] Now, the current temperature inside the tank is set to the current set temperature SV1.
Now, if we consider the case where the temperature is raised to a higher target setting temperature SV2 at the temperature change rate A1, as shown in FIG. and when the rate of change A1 is equal to or higher than the predetermined rate of change PA1, according to the instruction from the regulator 5,
The compressor 32 is stopped, and the temperature is raised at a desired temperature change rate A1 by controlling the heater 2.

When at least one of the conditions T1<PT1 and A1<PA1 holds, the compressor 32 remains as it is, that is, if it is stopped, it remains stopped, and if it is running, the compressor 32 continues to operate as it is. As it is, the temperature is raised at a desired rate of temperature change A1 by controlling operation of the heater 2. To explain the case of lowering the temperature, let us assume that the current temperature in the tank is the current set temperature SV10, and now consider the case where the temperature is lowered to the lower target set temperature SV20 at the temperature change rate A2. As shown, when the difference T2 between the temperatures SV10 and SV20 is greater than or equal to the predetermined value PT2, and the rate of change A2 is equal to the predetermined rate of change PA2.
In the above case, the compressor 32
or when it is already in operation, the motor 35 opens the expansion valve 34 to a predetermined opening degree to increase the cooling capacity, and the desired temperature change is achieved by controlling the heater 2. The temperature is lowered at a rate of A2. T2<PT
2 and A2<PA2, the compressor 32 remains stopped, that is, if it is stopped, it remains stopped, and if it is running, the current refrigerator operation is maintained, and the heating is continued. The temperature is lowered at a desired temperature change rate A2 by controlled operation of the device 2.

In both the temperature increase control and temperature decrease control described above, the capacity of the refrigerator 3 does not change during the control, so not only the difference between the final target set temperature and the current temperature in the tank but also the temperature change Since the rate is also taken into account, the rise or fall control is performed smoothly, accurately, and with the desired rate of temperature change. After reaching the final target temperature SV2 or SV20, steady-state control similar to the conventional one is performed based on instructions from the regulator 5.

It should be noted that instead of the valve 34 and the motor 35 for operating it in the embodiment described above, another expansion mechanism, for example, a plurality of capillary tubes with different inner diameters can be connected in parallel and each can be opened and closed by a solenoid valve as appropriate. You may also adopt the following. It is also conceivable to make the cooling capacity variable by allowing the cooler 31 and the expansion mechanism connected thereto to be bypassed by a circuit including another expansion mechanism.

[0021]

As explained above, according to the present invention, when raising or lowering the temperature inside the tank to the target set temperature at a desired temperature change rate, it is possible to raise or lower the temperature with high accuracy and smoothly. A descent control method can be provided.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an example of an apparatus for carrying out the method of the present invention.

FIG. 2 is an explanatory diagram of an example of temperature increase control according to the present invention.

FIG. 3 is an explanatory diagram of an example of temperature drop control according to the present invention.

[Explanation of symbols]

SV1, SV10 Current temperature (current set temperature) SV2
, SV20 Target set temperature T1, T2 Difference between current temperature and target set temperature PT1, P
T2 Predetermined temperature difference A1, A2 Desired temperature change rate PA1, PA2 Predetermined temperature change rate 1 Constant temperature bath 2 Heater 3 Freezer 31 Cooler 34 Expansion valve 35 Stepping motor 5 Controller 51 Setting panel

Claims (1)

[Claims] [Claim 1] A temperature increase that raises or lowers the inside of the tank to be temperature-controlled toward a target set temperature at a desired rate of temperature change;
In the drop control method, an in-tank heating means and an in-tank cooling means are prepared, and when the temperature in the tank is changed to a target set temperature higher than the current temperature, the difference between the set temperature and the current temperature is determined in advance. When the desired rate of temperature change is greater than or equal to a predetermined value, the cooling means is stopped and the heating means is operated in a controlled manner to control the temperature rise, and if not, the cooling means is operated or stopped. In order to control the temperature rise by operating the heating means under the current condition and change the temperature inside the tank to a target set temperature lower than the current temperature, the difference between the set temperature and the current temperature must be at least a predetermined value. and when the desired rate of temperature change is equal to or higher than a predetermined value, the cooling means is operated, and if it is already in operation, its cooling capacity is increased and the heating means is operated in a controlled manner to control the temperature drop; When this is not the case, the cooling means is stopped or the current state of operation is maintained, and the temperature is controlled to be lowered by controlling the heating means.