JP2018048794A - Cooling circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling circuit capable of utilizing hot gas.SOLUTION: A cooling circuit includes: a first circuit part for introducing a refrigerant by the cooling circuit into a cooling device so as to cut it off; a second circuit part for introducing a high temperature high pressure gas discharged from a compressor into a cooler so as to cut it off; and a third circuit part for introducing a high pressure liquid refrigerant discharged from a condenser into the cooler so as to cut it off. A control device includes: a cooling mode in which the refrigerant cooled by the first circuit part is introduced into the cooler, and the second circuit part and the third circuit part are cut off; and a temperature control mode in which the first circuit part is cut off, and one of the second circuit part and the third circuit part is selected and introduced into the cooler according to a predetermined temperature condition determined in advance.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an improvement in an economical cooling circuit that is provided in a cooling circuit used for a temperature cycle test and the like and can control the temperature of a low temperature chamber by introducing hot gas into a cooler such as an evaporator. Is.

Conventionally, as shown in FIG. 4, the cooling circuit 21 includes a compressor 22, a condenser 23, a decompression device 24, and a cooler 25 in the low temperature chamber 25 </ b> A, and circulates a refrigerant to lower the temperature. The chamber 25A is cooled.
A low temperature chamber heater 26 is provided in the low temperature chamber 25A, and this also achieves a temperature balance while simultaneously generating heat.
Further, for example, in the food refrigerator of Japanese Patent Application Laid-Open No. 2000-249455, the temperature of the food temperature sensor reaches the set temperature after the food is put into the warehouse, and the refrigerant temperature detected by the refrigerant temperature sensor. Is provided with means for raising the temperature of the cooler to near the set temperature when the temperature is equal to or lower than the set temperature, and the means is means for guiding hot gas from the compressor to the cooler. .
However, high pressure liquid hot gas from the condenser outlet was not utilized.
Moreover, in the cooling system of Unexamined-Japanese-Patent No. 2001-21241, the hot-gas defrosting means which supplies the defrosting hot gas to an evaporator, and the off cycle defrosting means which stops supply of the refrigerant | coolant to an evaporator at the time of a defrost operation And a means for selecting and executing either one of the two means under a predetermined condition, the set temperature in the chamber where the evaporator is located is not more than a predetermined temperature, and the coil temperature of the evaporator A cooling system is disclosed that selects off-cycle defrosting means when the temperature is above the freezing point temperature, and selects hot gas defrosting means when the coil temperature of the evaporator is below the freezing point temperature.
In the said structure, hot gas was used only for the purpose of defrosting.

JP 2000-249455 A JP 2001-21241 A

  The present invention was devised in view of the above circumstances, and its main problem is that the high-temperature and high-pressure gas refrigerant discharged from the compressor of the cooling circuit or the high-pressure liquid refrigerant discharged from the condenser is branched from the cooling circuit. Thus, it is an object of the present invention to provide a cooling circuit that can be introduced into a cooler such as an evaporator without passing through a decompression device so as to control the temperature rise of the low temperature chamber.

The present invention relates to a cooling circuit having a compressor, a condenser, a pressure reducing device, and a cooler in a low temperature chamber.
A first circuit portion that introduces refrigerant discharged from the decompression device by the cooling circuit into the cooler; and a first circuit portion that introduces high-temperature and high-pressure gas refrigerant discharged from the compressor into the cooler without passing through the condenser and the decompression device. Two circuit parts, and a third circuit part for introducing the high-pressure liquid refrigerant discharged from the condenser into the cooler without passing through the decompression device,
The control device introduces the refrigerant cooled by the first circuit unit into a cooler, shuts off the second circuit unit and the third circuit unit, shuts off the first circuit unit, A temperature control mode in which either one of the second circuit unit or the third circuit unit is selected according to a predetermined temperature condition set in advance, the other is opened, the other is shut off, and the refrigerant is introduced into the cooler. Features.

In the cooling circuit of the present invention, in addition to the cooling mode consisting of a normal cooling cycle, in the temperature control mode, a high-temperature high-pressure gas discharged from the compressor or a medium-high-pressure refrigerant discharged from the decompression device is selected. The temperature can be raised by supplying it to the cooler, which is economical because it does not require a temperature rise using a conventional heater, and prevents the cooler from having a strong frost. Can do.
In addition, since a high-temperature and high-pressure gas or liquid medium flows in the cooler, the oil return is good.
In addition, since there is no frosting, the efficiency increases and the cooler and the compressor can be miniaturized.
Furthermore, since there is no frosting, continuous operation for a long period of time is possible, and defrosting is unnecessary.
Also, the test time can be shortened in the temperature cycle test.
A heater for adjusting the temperature becomes unnecessary, and if necessary, a small-capacity defrosting heater dedicated to defrosting may be attached as an auxiliary.
In addition, since it has a simple configuration, it can be widely applied to products having a cooling circuit equipped with a cooler as well as an environmental tester such as an impact test, thereby realizing energy saving.

It is a circuit diagram of the cooling circuit which uses a 1st circuit. It is a circuit diagram of the cooling circuit which uses a 2nd circuit. It is a circuit diagram of the cooling circuit which uses a 3rd circuit. It is a circuit diagram which shows the conventional cooling circuit.

  A preferred embodiment in which a circuit for supplying a high-temperature and high-pressure gas refrigerant or a high-pressure liquid refrigerant is provided in the cooling circuit of the present invention will be described below.

FIG. 1 is a schematic diagram showing an outline of a cooling circuit 1 having a compressor 2, a condenser 3, an electronic expansion valve 4 as an example of a decompression device, and an evaporator 5 as an example of a cooler in a low temperature chamber 5A. In this embodiment, the present invention is applied to a cooling circuit used in an environmental tester for performing a temperature cycle test.
That is, in this cooling circuit 1, the refrigerant gas is pressurized by the compressor 2 to be a high-temperature high-pressure gas of about 80 to 90 ° C., and the high-temperature high-pressure gas is heat-exchanged by the condenser 3 to release heat, and 30 to 40 ° C. It condenses into a high-pressure refrigerant liquid at a medium temperature.

The liquefied high-pressure refrigerant liquid is decompressed by the electronic expansion valve 4 to become a low-pressure cooled refrigerant liquid, and the evaporator 5 evaporates the low-pressure refrigerant liquid and exchanges heat with air to form a low-pressure refrigerant gas. The cycle returns to 2.
In the present embodiment, a defrosting heater 6 is provided as an auxiliary in the low temperature chamber 5A.
A first electromagnetic valve 11 as a first on-off valve is provided between the condenser 3 and the electronic expansion valve 4 to form a first circuit portion C1.

The cooling circuit 1 is connected to a second circuit part C2 (gas line) and a third circuit part C3 (liquid line) for temperature control using hot gas (see FIGS. 1 to 3).
That is, the second circuit portion C2 branches between the compressor 2 and the condenser 3, and the pulse motor operated valve 14 shown as an example of the flow rate adjusting valve via the second solenoid valve 12 as an example of the second on-off valve. Is provided.
The pulse motor operated valve 14 is connected to the evaporator 5 without passing through the electronic expansion valve 4.

  Similarly, the third circuit portion C3 branches between the condenser 3 and the electronic expansion valve 4, in this embodiment, between the condenser 3 and the first electromagnetic valve 11, and is an example of a third on-off valve. The third motor valve 13 is connected to the pulse motor operated valve 14.

  Since the circuit configuration is as described above, the valve control unit 10 provided in the controller of the cooling circuit 1 is configured to perform the first operation based on the measured values of a temperature sensor or the like (not shown) according to the operation test conditions set by the environmental tester. The temperature control is performed by automatically selecting the first circuit unit C1, the second circuit unit C2, or the third circuit unit C3.

  That is, the valve control unit 10 has a cooling mode and a temperature control mode. Based on the set operation test conditions (such as a temperature cycle test), the valve control unit 10 receives from each sensor group connected to the valve control unit 10. The opening / closing control of the first to third electromagnetic valves 11 to 13 and the pulse motor operated valve 14 is performed while comparing the detection data.

  In the cooling mode in which the low greenhouse 5A is cooled to a predetermined temperature, as shown in FIG. 1, the first electromagnetic valve 11 is opened, the second electromagnetic valve 12 and the third electromagnetic valve 13 are closed, and the refrigerant is compressed. The low temperature chamber 5 </ b> A is cooled by a normal cooling cycle that sequentially passes through the machine 2, the condenser 3, and the electronic expansion valve 4 and supplies it to the evaporator 5.

Next, in the temperature control mode in which the temperature of the low temperature chamber 5A is raised, the supply of the refrigerant to the electronic expansion valve 4 is shut off as shown by the solid lines in FIGS.
That is, the first electromagnetic valve 11 is closed.
At the same time, either the second solenoid valve 12 or the third on-off valve 13 is selectively opened and the other is closed in accordance with the temperature to be raised.

  That is, when the second solenoid valve 12 is opened, the first solenoid valve 11 and the third solenoid valve 13 are closed, and the refrigerant of the high-temperature high-pressure gas of about 80 to 90 ° C. discharged from the compressor 2 is condensed. Instead of entering the vessel 3, it is supplied directly to the evaporator 5 via the pulse motor operated valve 14 (see FIG. 2).

  When the third solenoid valve 13 is opened, the first solenoid valve 11 and the second solenoid valve 12 are closed, and the high-pressure liquid medium discharged from the condenser 3 is about 30 to 40 ° C. 4 does not pass through and is supplied directly to the evaporator 5 via the pulse motor operated valve 14 (see FIG. 3).

  Thus, the valve control unit 10 determines whether to use the high-temperature / high-pressure gas refrigerant or the high-pressure liquid refrigerant in order to increase the temperature from a low temperature at a preset interval in a temperature cycle test or the like. By using the two circuit part C2 or the third circuit part C3, the temperature can be efficiently raised to a predetermined temperature.

  In controlling the temperature rise or the like, the bubble control unit 10 is based on the data detected by each sensor group for the temperature difference between the temperature set by the operator and the current temperature of the low temperature chamber, the sample load fluctuation, and the like. Automatically determines the use of the second circuit unit C2 or the third circuit unit C3, and controls the pulse motor operated valve 14 with the output signal from the control unit 10 to obtain the optimum opening degree. Adjust the flow rate with.

In this embodiment, a defrosting heater 6 is used in an auxiliary manner.
Since this defrosting heater 6 is not used as a heater for temperature control such as a temperature cycle test, it is normally kept OFF.
Since the defrost heater 6 is energized only when used for defrosting, the amount of electricity used can be suppressed as much as possible with a small capacity heater.

Note that a flexible pipe 15 is preferably provided in the circuit between the pulse motor operated valve 14 and the evaporator 5.
This is because the circuit from the pulse motor-operated valve 14 is connected to the circuit through which the decompressed refrigerant passes in the normal first circuit section C1, and therefore the high-pressure gas or liquid is connected to the circuit from the connection point to the evaporator 5. The refrigerant passes through and prevents metal fatigue due to vibration.

Similarly, a check valve 16 is provided between the electronic expansion valve 4 and the evaporator 5 between the connection position of the circuit of the pulse motor operated valve 14 and the electronic expansion valve 4 so that high-pressure gas or liquid does not flow backward. It is preferable to do so.
That is, the check valve 16 prevents the backflow to the electronic expansion valve 4 when the second solenoid valve 12 or the third solenoid valve 13 is opened and a high-temperature high-pressure gas refrigerant or a high-pressure liquid refrigerant flows. This is to prevent the expansion valve 4 from being damaged.

  In addition, when the said valve control part 10 has selected the 1st solenoid valve 11, when a temperature controller becomes a low temperature heater PID control output and the 2nd solenoid valve 12 or the 3rd solenoid valve 13 is selected, Control is switched to the hot gas PID control output.

  With the above configuration, in the conventional type (see FIG. 4), since the compressor is operated continuously, it is necessary to maintain the set temperature while maintaining the temperature balance while simultaneously generating heat in the low temperature chamber heater. Then, the compressor 2 is continuously operated during cooling, but at the time of control such as temperature rise, instead of the low temperature chamber heater, either the high temperature / high pressure gas refrigerant or the high pressure liquid refrigerant is directly flowed into the cooler. Balance is maintained to maintain the set temperature for temperature cycling tests.

Thus, in this embodiment, the pressure reducing device (electronic expansion valve 4) and the flow rate adjusting valve (pulse motor operated valve 14) do not operate simultaneously in synchronization.
The defrosting heater 6 is energized only at the time of defrosting, and the power consumption can be suppressed as compared with the conventional structure.

The present invention is not limited to the above embodiment, and all or a part of the first to third on-off valves may be composed of electromagnetic valves or electric valves.
The flow rate adjusting valve is not limited to the pulse motor operated valve, but may be any valve that can adjust the flow rate.
Further, the second on-off valve and the third on-off valve are connected in series to one flow rate adjusting valve, but the flow rate adjusting valve is omitted, and the second and third on-off valves are used as flow rate adjusting valves in parallel with the cooler. You may connect.
In addition, it goes without saying that various design changes can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Cooling circuit 2 Compressor 3 Condenser 4 Electronic expansion valve (pressure reduction device)
5 Evaporator (cooler)
6 Defroster heater 10 Valve controller 11 First solenoid valve (first on-off valve)
12 Second solenoid valve (second on-off valve)
13 Third solenoid valve (third on-off valve)
14 Pulse motor operated valve (Flow control valve)
15 Flexible pipe 16 Check valve 17 Dryer C1 1st circuit part C2 2nd circuit part C3 3rd circuit part

Claims (6)

In a cooling circuit having a compressor, a condenser, a pressure reducing device, and a cooler in a low temperature chamber,
A first circuit portion that introduces refrigerant discharged from the decompression device by the cooling circuit into the cooler; and a first circuit portion that introduces high-temperature and high-pressure gas refrigerant discharged from the compressor into the cooler without passing through the condenser and the decompression device. Two circuit parts, and a third circuit part for introducing the high-pressure liquid refrigerant discharged from the condenser into the cooler without passing through the decompression device,
The control device introduces the refrigerant cooled by the first circuit unit into a cooler, shuts off the second circuit unit and the third circuit unit, shuts off the first circuit unit, A temperature control mode in which either one of the second circuit unit or the third circuit unit is selected according to a predetermined temperature condition set in advance, the other is opened, the other is shut off, and the refrigerant is introduced into the cooler. Characteristic cooling circuit. The first circuit portion has a first on-off valve for passing the refrigerant between the condenser of the cooling circuit and the decompression device;
The second circuit part has a second on-off valve for passing the refrigerant of the high-temperature high-pressure gas discharged from the compressor between the compressor and the condenser;
The third circuit portion has a third on-off valve for passing the refrigerant of the high-pressure liquid discharged from the condenser between the condenser and the first on-off valve;
The second circuit portion and the third circuit portion are connected to a flow rate adjustment valve connected to a cooler,
In the cooling mode of the control device, when cooling the low temperature chamber, the first on-off valve is opened and the second electromagnetic valve and the third electromagnetic valve are closed for cooling. In the temperature control mode, the first on-off valve is used. And the first on-off valve is closed, one of the second on-off valve and the third on-off valve is opened, and the third on-off valve is opened to introduce a gas or liquid refrigerant into the cooler according to the temperature condition. A cooling circuit characterized in that it can.   The cooling circuit according to claim 1 or 2, wherein a flexible pipe is used for a part or all of the circuit between the flow regulating valve and the cooler.   The cooling circuit according to claim 1, wherein a check valve is provided between the pressure reducing device and the cooler.   5. The system according to claim 2, wherein all or a part of the first to third on-off valves is made of an electromagnetic valve or an electric valve, and the flow rate adjusting valve is made of a pulse electric valve. The cooling circuit described.   The cooling circuit according to claim 1, wherein a heater for defrosting the low temperature room is provided as an auxiliary to the low greenhouse.

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