JPH0245105B2 - REITOREIKYAKUSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refrigeration/cooling system, and more particularly to a refrigeration/cooling system that can prevent abnormal stoppage during defrosting operation.

For example, in a conventional refrigeration cooling system having multiple evaporators, high-temperature, high-pressure refrigerant gas is supplied from a compressor to one of the multiple evaporators, the defrosting side evaporator that is being defrosted. Driving takes place. The refrigerant liquefied by the defrosting of this defrosting side evaporator is supplied to the other re-evaporating side evaporator of the plurality of evaporators, and freezing and cooling operations are performed in this re-evaporating side evaporator. At the same time, the refrigerant liquid is re-evaporated into refrigerant gas, which is returned to the compressor. In this conventional refrigeration and cooling system, one of the multiple evaporators acts as a condenser and the other acts as a re-evaporator for re-evaporating, so the number of evaporators acting as evaporators is reduced. The gas pressure of the refrigerant gas on the suction side of the compressor (hereinafter referred to as low pressure) drops significantly.
Furthermore, at the start of defrosting operation, a large amount of frost has adhered to the defrosting side evaporator, so the condensing capacity becomes larger than necessary, and the gas pressure (hereinafter referred to as high pressure) of the refrigerant gas on the discharge side of the compressor increases. descend. As the high pressure decreases, the pressure difference between the high pressure side and the low pressure side becomes smaller before and after the pressure reducing valve provided before the evaporator, the flow rate of refrigerant to the low pressure side decreases, and the low pressure decreases. When the low pressure reaches the lower limit of use due to these factors, the low pressure detector operates to stop the operation of the compressor. Therefore, there was a problem that the above-mentioned defrosting operation and freezing/cooling operation could not be performed. Further, the above-mentioned problems also occur in reverse cycle defrosting operation.

This invention attempts to solve the above-mentioned problem, and uses a conventional low-pressure pressure detector as a first low-pressure pressure detector, and in addition, a second low-pressure pressure detector with a lower set value than the first low-pressure pressure detector. The second low-pressure pressure sensor detects the first one only during defrosting operation.
The purpose of the present invention is to provide a refrigeration/cooling system that can maintain normal operation by a simple means by disabling the operation of a low-pressure pressure detector to prevent a compressor from stopping due to an abnormal drop in suction pressure during defrosting operation. It is said that

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a refrigerant circulation path diagram of a refrigeration cooling device according to an embodiment of the present invention. In FIG. 1, 1 is a compressor that compresses the refrigerant, 2 is a condenser that condenses the refrigerant gas compressed by the compressor 1, and 6 and 7 are the first and second compressors that reduce the pressure of the refrigerant condensed in the condenser 2. 2 pressure reducing valve,
Reference numerals 8 and 9 denote first and second evaporators that exchange heat with the load and return the refrigerant whose pressure has been reduced from the first and second pressure reducing valves 6 and 7 to the compressor 1. The main part of the refrigeration cycle is configured, and a first pressure reducing valve 6 and an evaporator 8, and a second pressure reducing valve 7 and an evaporator 9 are provided in parallel. Also, 3, 4,
5, 12, 13, 14, and 15 are first, second, third, fourth, fifth, sixth, and seventh solenoid valves;
0, 11 are the first and second temperature detection elements, 16, 1
Reference numeral 7 indicates first and second low-pressure pressure detectors, and reference numerals 18 and 19 indicate first and second check valves.

In the refrigeration/cooling system of this embodiment, high-temperature, high-pressure refrigerant gas compressed by a compressor 1 is condensed and liquefied in a condenser 2, and then divided through a first electromagnetic valve 3.
the first and third electromagnetic valves 4 and 5 respectively
It is supplied to the second pressure reducing valves 6 and 7. The first and second pressure reducing valves 6 and 7 reduce the pressure of the refrigerant condensed and liquefied in the condenser 2 and supply it to the first and second evaporators 8 and 9.
The first and second evaporators 8 and 9 exchange heat between the supplied refrigerant and the load to freeze and cool the load. The first and second temperature detection elements 10 and 11 are
detecting the temperature of the refrigerant gas discharged from the evaporators 8 and 9;
The reduced pressure of the first and second pressure reducing valves 6 and 7 is controlled by the output. The refrigerant gas discharged from the first and second evaporators 8 and 9 is transferred to the fourth and fifth electromagnetic valves 12 and
13 and is returned to the suction side of the compressor 1. That is, during refrigeration or cooling operation, compressor 1 → condenser 2 → first solenoid valve 3 → second and third solenoid valves 4 → first pressure reducing valve 6 → first evaporator 8 → first solenoid valve 5 → second pressure reducing valve 7 → second evaporator 9 → fourth solenoid valve 12 5 solenoid valve 13 = cooling cycle operation of compressor 1 is performed.

Next, when defrosting the first evaporator 8, the first, second, and fourth solenoid valves 3, 4, and 12 are closed, and the sixth
The solenoid valve 14 is opened, and the first defrosting cycle operation as shown by the solid line in the figure is performed. That is,
Compressor 1 → sixth solenoid valve 14 → first evaporator 8 →
First check valve 18 → third solenoid valve 5 → second pressure reducing valve 7 → second evaporator 9 → fifth solenoid valve 13 → first defrosting circuit of compressor 1 Perform the defrost cycle operation of step 1. Through this first defrosting cycle operation, the high-temperature, high-pressure refrigerant gas from the compressor 1 is supplied to the first evaporator 8 to defrost the first evaporator 8 and to remove the frost from the first evaporator 8. itself is converted into a liquid refrigerant. The refrigerant liquefied in the first evaporator 8 is supplied to the second evaporator 9 via the first check valve 18, the third solenoid valve 5, and the second pressure reducing valve 7. After the load is frozen and cooled in the second evaporator 9, it is returned to the compressor 1 via the fifth electromagnetic valve 13.

Next, when the defrosting of the first evaporator 8 is completed, the first, third, fifth, sixth solenoid valves 3, 5, 13,
14 is closed, and the second, fourth, and seventh solenoid valves 4,
12, 15, and 18 are opened, and a second defrosting cycle operation as shown by the broken line in FIG. 1 is performed. That is, compressor 1 → seventh solenoid valve 15 → second evaporator 9 → second check valve 19 → second solenoid valve 4 → first pressure reducing valve 6 → first evaporator 8 → first 4 solenoid valve 1
2->A second defrost cycle operation is performed by the second defrost circuit of the compressor 1. By this second defrosting cycle operation, the high temperature, high pressure refrigerant gas from the compressor 1 is supplied to the second evaporator 9 to defrost the second evaporator 9 and to remove the frost from the second evaporator 9. It is turned into a liquid refrigerant. The refrigerant liquefied in the second evaporator 9 is passed through the second check valve 19 and the second electromagnetic valve 4.
It is supplied to the first evaporator 8 via the first pressure reducing valve 6, and after freezing and cooling the load in the first evaporator 8, it is returned to the compressor 1 via the fourth electromagnetic valve 12. .

Note that the first and second low-pressure pressure detectors 16 and 17
is arranged near the suction port of the compressor 1, the first low-pressure pressure detector 16 is set to the lower limit of the low-pressure pressure that can be continuously operated, for example, 1.5 Kg/cm ² G, and the second low-pressure pressure detector The container 17 is 0~ which can prevent vacuum operation.
It is set to 0.2Kg/cm ² G setting value.

FIG. 2 shows an electrical circuit diagram of the main parts of the above-described embodiment of the invention. In Figure 2, SW is the operation switch,
MC is the electric motor for compressor 1, 52C is the electric motor MC
52C1 is the contact of the electromagnetic contactor 52C, LPS1 is the contact of the first low pressure pressure sensor 16, LPS2 is the contact of the second low pressure pressure sensor 17,
T is the defrost timer, T1 is the contact point of the defrost timer T,
1 and X2 are the first and second relays, X21 is the contact point of the second relay X2, and SS is a group of safety switches.
And the contact point LPS2 of the second low pressure pressure sensor 16
and the contact X21 of the second relay X2 are connected in series, and the contact LPS2 of the first low pressure pressure sensor 16
is connected in parallel to the electromagnetic contactor 52C1 of the electric motor MC.

Next, the operation of this electric circuit will be explained.
First, when the operation switch SW is turned on, the electromagnetic contactor 52C is energized, its contact 52C1 is closed, the electric motor MC is operated, and the above-mentioned cooling operation is performed. During such a cooling operation, when the defrosting timer T, which is set in advance to a predetermined time, operates, the first relay X1 is deenergized and at the same time the second relay X2 is energized. By deenergizing the first relay X1,
By opening and closing the contacts (not shown) of this relay X1, a defrosting electric circuit (not shown) is operated, and the above-mentioned defrosting operation is performed. On the other hand, the second relay
The contact X21 of is closed, and the contact LPS1 of the first low pressure sensor 16 is short-circuited by this and the contact LPS2 of the second low pressure sensor 17. Therefore, during defrosting operation, the low pressure decreases and the first
The low pressure pressure sensor 16 operates, and its contact LPS1
Even if the circuit is opened, the defrosting operation continues unless the low pressure falls to the set value of the second low pressure pressure detector 17. Furthermore, after a predetermined period of time has elapsed, the defrost timer T is activated, the first relay X1 is energized again, the second relay X2 is deenergized, and the cooling operation is resumed. It should be noted that the time period during which the low pressure drops abnormally during defrosting operation is very short, and even if the pressure is lower than the setting value of the first low pressure pressure detector 16, there is no effect on the life of the compressor 1. It is sufficient that the number is extremely small and that the second low-pressure pressure sensor 17 can prevent the compressor 1 from operating under vacuum. this is,
When the compressor is operated under vacuum, if there is a gas leak, even a small amount, it will suck in non-condensable gas from there.
This is because the high pressure increases abnormally during cooling operation.

As explained above, the refrigeration/cooling device of the present invention controls the operation of the first low pressure detector to prevent continuous operation at an abnormally low pressure during normal cooling operation, when the set value is set to the first low pressure. The second low-pressure pressure detector is set to a value lower than that of the detector and greater than 0 kg/cm ² G, and is disabled only during defrosting operation. This has the effect of preventing abnormal stoppage of the compressor and realizing normal defrosting and cooling operations at low cost by simply adding one commonly used pressure detector that operates at a set pressure.

[Brief explanation of the drawing]

FIG. 1 is a refrigerant circulation path diagram of a freezing and cooling apparatus according to an embodiment of the present invention, and FIG. 2 is an electrical circuit diagram of a main part of the freezing and cooling apparatus of the above embodiment. 1...Compressor, 2...Condenser, 6, 7...First, second
pressure reducing valves, 8, 9...first and second evaporators, 16...
1st low-pressure pressure detector, 17...2nd low-pressure pressure detector, T...defrost timer, T1...contact of defrost timer, X1, X2...first, second relay, X21...
Contact of second relay, LPS1... Contact of first low pressure pressure detector, LPS2... Contact of second low pressure pressure detector, MC... Electric motor for compressor, SW... Operation switch, 52C... Magnetic contactor, 52C1...Contact of electromagnetic contactor.

Claims (1)

[Claims] 1 A compressor that compresses refrigerant, a condenser that condenses the refrigerant gas compressed by this compressor, a pressure reducing valve that reduces the pressure of the refrigerant condensed by this condenser, and the refrigerant that has been reduced in pressure by the pressure reducing valve is supplied. and a plurality of evaporators that return the refrigerant to the compressor after exchanging heat with the load, and defrosting the evaporator by supplying the refrigerant compressed by the compressor to the evaporator. A first low-pressure pressure detector is provided on the suction side of the compressor, and operates when the suction side pressure during cooling operation is abnormally reduced to be below a set pressure to control the stopping of the cooling operation; A second low-pressure pressure detector is provided on the suction side of the compressor and operates at a suction pressure lower than the set pressure set by the first low-pressure pressure detector, and is energized by the defrost command signal during defrosting operation. and means for short-circuiting the contacts of the first low-pressure pressure detector to disable its operation by means of a series circuit of the contacts of the relay and the contacts of the second low-pressure pressure detector. Refrigeration and cooling equipment.