JPH10185414A - Cooler for a plurality of show cases - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooler which can perform necessary and sufficient defrosting separately for each show case, and besides is simple in structure, in a cooler for cooling show cases by one unit of freezer. SOLUTION: At defrosting operation, a non-condensive gas refrigerant is sent from the liquid receiver 6 of a freezer 1 to all show cases 8 and 9, and the defrosting is performed by the latent heat of the gas refrigerant, and when the defrosting of the cooling coil in any show case is finished, the liquid refrigerant from the liquid receiver 6 is sent from the freezer to all show cases 6, and in the show case where defrosting is finished, the cooling operation is performed, and in the show case where the defrosting is not finished, the defrosting by the sensible heat of the liquid refrigerant is performed further.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for cooling a plurality of showcases with one refrigerator.

[0002]

2. Description of the Related Art In a cooling device that cools a plurality of showcases with a single refrigerator, the number of showcases depends on various conditions such as the size and set temperature of the showcase, the type of displayed products, and the frequency of taking in and out. The amount of frost on the cooling coil differs for each case.

[0003] If the same defrosting operation is performed for all showcases, there is a problem that some of the showcases may have poor defrosting or a rise in temperature. There is also a problem that piping and control become complicated to perform defrosting.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a cooling device for a plurality of showcases, which can perform necessary and sufficient defrosting for each showcase and has a simple structure.

[0005]

To achieve the above object, a cooling device for a plurality of showcases according to the present invention comprises a refrigerant having one end connected to a liquid refrigerant outlet of the receiver of a refrigerator having a compressor, a condenser and a receiver. Between the other end of the outgoing pipe and the other end of the refrigerant return pipe having one end connected to the suction side of the compressor, a plurality of refrigerant pipes each having an expansion valve and a cooling coil provided in a refrigerant pipe extending from the refrigerant inlet to the same outlet. The showcases are connected in parallel, and the refrigerant outward pipe is opened during the cooling operation but closed at the start of the defrosting operation, and the defrosting of the cooling coil in any one of the plurality of showcases is performed. The main liquid valve which is opened when the operation is completed is provided, and the liquid receiver is provided with a gas refrigerant outlet facing the gas phase of the liquid receiver, and the other end of the gas sending pipe having one end connected to the outlet is provided with the refrigerant. Connect to the downstream side of the main liquid valve in the A main gas valve that is closed during the cooling operation but is opened at the start of the defrosting operation and is closed when the defrosting of the cooling coil in one of the plurality of showcases is completed, In addition, the refrigerant pipe upstream of the expansion valve of each showcase is appropriately opened and closed according to the temperature in the showcase during the cooling operation, but is closed at the start of the defrosting operation, and the cooling coil in the showcase is opened. A main valve that is opened when defrosting is completed is provided, and the other end of a bypass pipe having one end connected to the upstream side of the main valve is connected to an inlet of a cooling coil, and the bypass pipe is closed during cooling operation. A bypass valve that is opened at the start of the defrosting operation and closed when the defrosting of the cooling coil in the showcase is completed, and when a timer is set in advance. When it becomes, the defrost start command is issued to the refrigerator and each showcase, and when the defrosting of each showcase is completed and the outlet pipe temperature of the cooling coil reaches a predetermined temperature, the refrigerator and the showcase where the defrosting is completed. A control device that issues a defrost return command is provided, and when a defrost start command is issued from the control device, the main liquid valve in the refrigerator and the main valve of each showcase are closed, and the main gas valve of the refrigerator and Bypass valves of each showcase are opened, gas refrigerant from the receiver is supplied to the cooling coils of all showcases, defrosting is performed by the latent heat of the gas refrigerant, and freezing is performed when a defrost return command is issued. When the main liquid valve of the machine is opened and the main gas valve is closed, liquid refrigerant is supplied from the refrigerator to all showcases, and defrosting is completed. In a showcase where no main valve is closed and the bypass valve is left open, a liquid refrigerant is supplied from the bypass pipe to the cooling coil, and defrosting is performed by sensible heat of the liquid refrigerant.
In a showcase where defrosting has been completed, the main valve is opened and the bypass valve is closed to perform a cooling operation.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the cooling device according to the present invention will be described below in detail with reference to specific examples shown in the accompanying drawings. The cooling device of the present invention cools a plurality of showcases with one refrigerator. In the present embodiment, two showcases are cooled with one refrigerator, and two showcases are provided. A specific example when the cooling coil is provided will be described.

In the refrigerator 1, the discharge side of the compressor 2 is connected to a refrigerant inlet of a condenser 4 via a discharge pipe 3, and the outlet is connected to a refrigerant pipe of a receiver 6 by a refrigerant pipe 5 having a flow control valve 5a. It is connected to the inlet 6a.

Liquid refrigerant outlet 6 facing the liquid phase in the lower part of liquid receiver 6
b is connected to the respective refrigerant inlets 10 and 10 of the first and second showcases 8 and 9 via the refrigerant outgoing pipe 7 including the main liquid valve ML, and the refrigerant outlets 11 and 11 of the respective showcases.
Is the accumulator 13 of the refrigerator 1 via the refrigerant return pipe 12.
Is connected to the suction side of the compressor 2 via a suction pipe 14.

The main liquid valve ML is normally open, but is closed at the start of the defrosting operation, and is opened when the defrosting of the cooling coil in any one of the showcases is completed.

The liquid receiver 6 is provided with a gas refrigerant outlet 6c facing the gas phase in the upper part of the liquid receiver. The gas refrigerant outlet 6c is connected by a gas supply pipe 15 provided with a flow control valve 15a and a main gas valve MG. The refrigerant outlet pipe 7 is connected to the downstream side of the main liquid valve ML, and the flow control valve 15a of the gas supply pipe 15 and the main gas valve M
One end of a branch pipe 16 provided with a capacity adjusting valve 16a is connected between G, and the branch pipe is connected in the middle of the suction pipe 14 of the compressor 2, and the capacity adjusting valve 16a in the branch pipe 16 is connected. An on-off valve CPV for the control valve is provided upstream of the control valve.

The main gas valve MG is normally closed, but is opened when the defrosting operation is started, and is closed when the defrosting of the cooling coil in any one of the showcases is completed. Is normally closed, but is opened at the start of the defrosting operation. The gas in the gas feed pipe 15 is sent to the suction side of the compressor 2 via the capacity adjusting valve 16a, and the gas pressure in the condenser 6 is adjusted appropriately. , And is closed after a predetermined time from the completion of the defrosting of the cooling coils in all the showcases or after the pressure in the condenser reaches a predetermined value.

In the first and second showcases 8 and 9, the refrigerant pipe 17 from the refrigerant inlet 10 is connected to the expansion valve 18 via the main valve MV which is opened only during the cooling operation.
The branch pipes 19a and 19b provided with a and 18b are connected to the respective refrigerant inlets of the cooling coils A and B.

[0013] Branch pipes 20a, 20a having suction valves SA, SB are provided at the refrigerant outlets of the cooling coils A, B, respectively.
b is connected to one end, and the other ends of both branch pipes 20a and 20b are joined and connected to the refrigerant outlet 11 of the showcase 8.

The main valve M in the refrigerant pipe 17
One end of a bypass pipe 21 is connected to the upstream side of V, and the other end of the bypass pipe 21 is connected to a bypass valve B
The cooling coils A and B are connected to respective refrigerant inlets through bypass branch pipes 21a and 21b having A and BB.

Further, return branch pipes 23a having check valves 22a and 22b are provided at the outlet sides of the cooling coils A and B, respectively.
One end of the return branch pipe 23a,
The other end of 3b is joined by the return pipe 23 and connected to the refrigerant pipe 17 downstream of the main valve MV.

The main liquid valve ML, the main gas valve MG and the opening / closing valve CPV for the capacity adjusting valve in the refrigerator 1 and the main valve MV, the bypass valves BA and BB in the showcases 8 and 9.
The suction valves SA and SB are electromagnetic on-off valves, and are controlled to open and close based on control signals of a defrost start command and a defrost return command issued from a control device (not shown). The details of the relationship between each control signal and the opening / closing operation of each valve by this signal will be described later.

The specific structure of the showcases 8 and 9 is, for example, as shown in FIG. 2, and the lower, back and upper air passages 25a and 25 are provided in the showcase body 24.
b, 25c are formed, and the air sucked in from the air inlet 27 by the driving of the fan 26 provided in the lower air passage is discharged from the air outlet 28 through the cooling coils A, B,
An air curtain is formed at the product entrance, and is again sucked into the intake port 27 and circulated.

In the cooling apparatus of this embodiment, even if one of the two cooling coils A and B is being defrosted, the other cooling coil continues the cooling operation. May be frozen by the cool air from the cooling coil during cooling to form an icicle between the cooling coils. As a countermeasure, an auxiliary heater 29 such as an electric heater is provided at the upper edge of the partition between the cooling coils A and B. Therefore, icicles are prevented from growing between the cooling coils. Reference numerals 30 and 30 in the drawing indicate shelves for displaying products.

Next, the operation of the cooling device having the above configuration will be described. The operation modes of the refrigerator 1 and the showcases 8 and 9 are switched by opening and closing operations of respective valves described later. First, the operation modes of the refrigerator will be described.

In the refrigerator 1, the high-temperature gas refrigerant from the compressor 2 is cooled and condensed by the condenser 4 and sent to the receiver 6 in a gas-liquid mixed state, where it is temporarily stored. The operation modes of the refrigerator 1 include a liquid refrigerant supply mode for supplying liquid refrigerant in the receiver 6 and a warm gas supply mode for supplying worm gas as a non-condensable gas refrigerant in the receiver.

<Liquid Refrigerant Supply Mode> In the liquid refrigerant supply mode, the main liquid valve ML is opened, the main gas valve MG is closed, and the receiver 6 is closed.
The inner and lower liquid refrigerant is sent from the liquid refrigerant outlet 6b to the two showcases 8 and 9 via the main liquid valve ML by the refrigerant outward pipe 7.

<Warm Gas Supply Mode> In the warm gas supply mode, the main liquid valve ML is closed and the main gas valve MG is opened, and the worm gas in the upper part of the receiver 6 is supplied from the gas refrigerant outlet 6c to the gas supply pipe. Through the main gas valve MG, the refrigerant is sent to the refrigerant outgoing pipe 7 through the refrigerant outgoing pipe 15, and the two showcases 8 and
It is sent to 9. The refrigerant that has passed through the two showcases 8 and 9 is drawn into the compressor 2 from the refrigerant return pipe 12 through the accumulator 13 and the suction pipe 14 regardless of the operation mode of the refrigerator 1.

Next, the flow of the refrigerant in the operation mode when the cooling coil A of each showcase is defrosted will be described with reference to FIGS.
This will be described based on the configuration diagram shown in FIG. In these figures, the arrows indicating the flow of the refrigerant are as follows:
The dashed arrows indicate the flow of the low-pressure gas refrigerant, and the double arrows indicate the flow of the worm gas.

<Cooling Mode> In the cooling mode, a liquid refrigerant is supplied from the refrigerator 1 and this liquid refrigerant is supplied to the expansion valve 18.
The cooling valves A and B are sent to the two cooling coils A and B via a and 18b. The main valve MV and the suction valves SA and SB in the showcase are opened, and the bypass valves BA and BB are closed.

As shown in FIG. 3, the liquid refrigerant flowing from the refrigerant inlet 10 into the refrigerant pipe 17 passes through the main valve MV to branch coils 19a, 19b and to the cooling coils A, B via expansion valves 18a, 18b, respectively. Sent and vaporized to generate cold heat.

The low-pressure gas refrigerant from the cooling coils A and B is supplied to the suction valves SA and S by branch pipes 20a and 20b, respectively.
The refrigerant flows into the refrigerant return pipe 12 from the refrigerant outlet 11 via B, and is returned to the refrigerator 1. The opening and closing of the main valve MV and the suction valves SA and SB are appropriately controlled in accordance with the temperature in the showcase, for example, by a signal from a thermostat for temperature control.

<Warm Gas Defrost Mode> In the warm gas defrost mode, the worm gas is supplied from the refrigerator 1, and the worm gas is sent directly to the cooling coil on one side by bypassing the expansion valve. When defrosting the cooling coil A, the bypass valve BA and the suction valve SB are opened, and the main valve MV, the bypass valve BB, and the suction valve SA are closed.

The warm gas flowing from the refrigerant inlet 10 into the refrigerant pipe 17 passes through the bypass pipe 21 as shown in FIG.
It is sent to the cooling coil A via the bypass valve BA by the bypass branch pipe 21a. The worm gas is condensed in the cooling coil A to become a liquid refrigerant, and melts the frost attached to the cooling coil by the latent heat.

The liquid refrigerant from the cooling coil A is returned to the return branch pipe 23.
a into the refrigerant pipe 17 downstream of the main valve MV through the return pipe 23 and the expansion valve 18 through the branch pipe 19b.
After passing through b, it is sent to the cooling coil B and vaporized to generate cold heat. The gas refrigerant from the cooling coil B passes through the branch valve 20b, passes through the suction valve SB, and flows from the refrigerant outlet 11 to the refrigerant return pipe 1
2 and is returned to the refrigerator 1.

<Liquid Defrost Mode> The liquid defrost mode is a mode for melting the frost that could not be melted by the warm gas defrost by the sensible heat of the liquid refrigerant. In the liquid defrost mode, a liquid refrigerant is supplied from the refrigerator 1, and the liquid refrigerant is sent to a cooling coil on one side, and defrosting is performed by sensible heat of the liquid refrigerant.
When the cooling coil A is defrosted, the bypass valve BA and the suction valve SB are opened, and the main valve MV, the bypass valve BB, and the suction valve SA are closed as in the warm gas defrost mode described above.

The liquid refrigerant flowing from the refrigerant inlet 10 into the refrigerant pipe 17 passes through the bypass pipe 21 as shown in FIG. 5, and is cooled by the cooling coil A through the bypass valve BA by the bypass branch pipe 21a.
Sent to. The liquid refrigerant melts the frost remaining in the coil by sensible heat in the cooling coil A, flows downstream of the main valve MV in the refrigerant pipe 17 by the return branch pipe 23a and the return pipe 23, and expands by the branch pipe 19b. After passing through 18b, it is sent to the cooling coil B and vaporized to generate cold heat.
The gas refrigerant from the cooling coil B flows into the refrigerant return pipe 12 from the refrigerant outlet 11 through the branch valve 20b via the suction valve SB, and is returned to the refrigerator 1.

<Pump Down Mode> In the pump down mode, the refrigerant remaining in the cooling coil at the time when the warm gas defrosting and the liquid defrosting are completed is vaporized and extracted so as not to hinder the next cooling operation. When the cooling coil A is defrosted, the suction valve SB is opened, and the other main valves MV, bypass valves BA, BB, and suction valve SA are all closed.

As shown in FIG. 6, the liquid refrigerant in the cooling coil A flows through the return branch pipe 23a, the return pipe 23 downstream of the main valve MV in the refrigerant pipe 17, and the branch pipe 19b passes through the expansion valve 18b. It is sent to B and vaporized, generating cold heat. The gas refrigerant from the cooling coil B flows into the refrigerant return pipe 12 from the refrigerant outlet 11 through the branch valve 20b via the suction valve SB, and is returned to the refrigerator 1.

After the pump down is completed, the cooling mode is returned to the cooling mode to perform the cooling operation. After a predetermined time has elapsed, the defrost operation of the cooling coil B is performed in the same manner as the defrost operation of the cooling coil A described above.

As described above, while one of the cooling coils A is being defrosted, the other cooling coil B always performs a cooling operation, and the refrigerant after the defrosting of the cooling coil A is cooled by the cooling coil B. The temperature rise in the showcase due to the defrosting operation can be made extremely small.

By the way, while the refrigerator 1 is in the warm gas supply mode, the operating modes other than the warm gas defrost mode cannot be set in both showcases.
While the refrigerator is in the liquid refrigerant supply mode, both showcases 8 and 9 can be individually set to either the cooling mode or the liquid defrost operation mode.

That is, in the apparatus of the present invention, worm gas is supplied to all showcases from the refrigerator to perform worm gas defrost by latent heat until the defrosting of the showcase with the least amount of frost is completed, and then the refrigeration is performed. The showcase, which has already supplied liquid refrigerant from the machine to all the showcases and has already completed defrosting, is switched to the cooling mode via the pump down mode, thereby preventing the temperature inside the showcase from rising and preventing defrosting. Incomplete showcases are subjected to liquid defrosting by sensible heat following warm gas defrosting, thereby preventing defective defrosting.

Next, a specific example of the operation mode switching when the cooling coil A of each showcase is defrosted will be described with reference to the relationship between the operation mode and the valve opening / closing operation in the refrigerator and each showcase shown in FIGS. This will be described in detail based on the time chart shown. In these figures, the symbols in the valve opening / closing operation column indicate that 〇 is open, X is closed, and △ indicates that opening / closing is controlled according to the temperature in the showcase.

FIG. 7 shows the case where the amount of frost formed on the first showcase 8 is larger than that of the second showcase 9.
9 shows a specific example where the amount of frost of the showcase 8 is smaller than that of the second showcase 9, and FIG. 9 shows a case where the amount of frost of the two showcases 8 and 9 is the same.

First, the case where the amount of frost formed on the first showcase 8 is larger than that on the second showcase 9 will be described. During the cooling operation of each showcase, the main liquid valve MV of the refrigerator 1 is opened, the main gas valve MG and the on-off valve C for the capacity adjusting valve are opened.
When the PV is closed, the liquid refrigerant supply mode is set. In the showcases 8 and 9, for example, the main valve MV according to the temperature in the showcase by a signal from a thermostat for temperature control.
Are appropriately opened and closed together with the suction valves SA and SB so that the inside of the showcase is maintained at a predetermined temperature, and the bypass valves BA and B
B is closed.

When a defrost time set in advance by a timer or the like is reached, a defrost start command (in this embodiment, a defrost start command for the cooling coil A of each showcase) is sent from the control device to the refrigerator 1 and both showcases 8 and 9.
The main liquid valve ML is closed in the refrigerator 1 and the main gas valve MG and the on-off valve CP for the capacity adjusting valve
V is opened, and in the showcases 8 and 9, the main valve MV and the suction valve SA are closed, and the bypass valve BA and the suction valve SB are opened.

The worm gas is supplied to each of the cooling coils A in the first and second showcases 8 and 9 by the opening / closing operation of the valve described above, and defrosting is performed by the latent heat of the worm gas.

When the defrosting of the cooling coil A in the second showcase 9 with a small amount of frost is completed, an increase in the outlet pipe temperature of the cooling coil A due to the completion of the defrost is detected by the control device. , A defrost return command is issued to the refrigerator 1 and the second showcase 9 after the defrosting is completed. In the refrigerator 1, when the defrost return command is issued, the main liquid valve MV is opened and the main gas valve MG is closed to switch to the liquid refrigerant supply mode.

In the second showcase 9 in which the defrosting has been completed, the bypass valve BA is closed, and after passing through the pump down mode, the main valve MV, the suction valves SA, SB are opened, and the operation returns to the cooling mode. . Also in this cooling mode, the main valve MV and the suction valves SA and SB are controlled to open and close as appropriate according to the temperature inside the showcase.

On the other hand, in the first showcase 8 in which defrosting has not been completed, each valve is kept open and closed in the worm gas defrost mode, and the liquid refrigerant from the refrigerator is replaced with the cooling coil A in place of the worm gas. And the liquid defrost is performed by the sensible heat of the liquid refrigerant.

When the defrosting of the first showcase 8 is completed, an increase in the outlet pipe temperature of the cooling coil A due to the completion of the defrosting is detected by the control device, and the first defrosting completed by the control device. A defrost return command is issued to the showcase 8.

When a defrost return command is issued, the bypass valve BA of the showcase 8 is closed to shift to the pump down mode. After the pump down mode, the main valve MV and the suction valves SA and SB are opened. Return to cooling mode. Even in this cooling mode, the main valve MV
In addition, the suction valves SA and SB are appropriately opened and closed according to the temperature in the showcase.

When the amount of frost on the first showcase 8 is smaller than that on the second showcase 9,
The opening / closing operation and action of the above-described valve are merely interchanged between the first and second showcases. As shown in FIG. 8, the first showcase 8 with a small amount of frost first stops defrosting and pumps down. After returning to the cooling operation via the mode, the second showcase 9 performs sufficient defrosting with the liquid defrost, and then returns to the cooling operation via the pump down mode.

When the frost formation amounts of both showcases are the same, as shown in FIG. 9, both showcases 8 and 9 do not perform the liquid defrost mode but go from the warm gas defrost mode to the cooling mode via the pump down mode. Return to.

[0050]

Since the cooling device for a plurality of showcases according to the present invention has the above-described configuration, the following operation and effect can be obtained. When the defrosting operation is started, warm gas as a non-condensed refrigerant in the receiver is sent from the refrigerator to all showcases, and when defrosting is completed in any one of the showcases, the refrigerator sends the show gas to all showcases. Since the liquid refrigerant in the receiver is sent, in a showcase where the amount of frost is small, sufficient defrost is performed in a short time by the latent heat of the warm gas, and then cooled by the liquid refrigerant supplied from the refrigerator. Be driven.

On the other hand, in the showcase where the amount of frost is large, after the defrosting by the warm gas is completed, the liquid refrigerant supplied from the refrigerator further performs sufficient defrosting by the sensible heat of the liquid refrigerant.

Therefore, for each showcase,
It is possible to perform necessary and sufficient defrost according to the amount of frost,
It is possible to prevent a rise in the temperature in the showcase and poor defrosting.

In a conventional cooling device of the type utilizing worm gas from a liquid receiver for defrosting, worm gas is generally sent to a showcase through a low-pressure pipe, but in the device of the present invention. Since the warm gas is sent to the showcase by the refrigerant outgoing pipe, which is the high-pressure pipe that sends the liquid refrigerant from the refrigerator to the showcase, no special warm gas piping is required between the refrigerator and the showcase. Can be constructed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a cooling device according to the present invention.

FIG. 2 is a longitudinal sectional view showing a specific example of the structure of a showcase.

FIG. 3 is a configuration diagram showing a flow of a refrigerant in a showcase in a cooling mode.

FIG. 4 is a configuration diagram showing a flow of a refrigerant in a showcase in a warm gas defrost mode.

FIG. 5 is a configuration diagram showing a flow of a refrigerant in a showcase in a liquid defrost mode.

FIG. 6 is a configuration diagram showing a flow of a refrigerant in a showcase in a pump down mode.

FIG. 7 is a time chart showing a specific example of a relationship between an operation mode and a valve opening / closing operation.

FIG. 8 is a time chart showing another specific example of the relationship between the operation mode and the valve opening / closing operation.

FIG. 9 is a time chart showing still another specific example of the relationship between the operation mode and the valve opening / closing operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Refrigerator 2 Compressor 3 Discharge pipe 4 Condenser 5 Refrigerant pipe 5a Flow control valve 6 Condenser 6a Refrigerant inlet 6b Liquid refrigerant outlet 6c Gas refrigerant outlet 7 Refrigerant forward pipe 8, 9 Showcase 10 Refrigerant inlet of showcase 11 Show Refrigerant outlet of case 12 Refrigerant return pipe 13 Accumulator 14 Suction pipe 15 Gas supply pipe 15a Flow control valve 16 Branch pipe 16a Capacity control valve 17 Refrigerant pipe 18a, 18b Expansion valve 19a, 19b Branch pipe 20a, 20b Branch pipe 21 Bypass pipe 21a , 21b bypass branch pipe 22a, 22b check valve 23 return pipe 23a, 23b return branch pipe 24 showcase body 25a, 25b, 25c air passage 26 fan 27 intake port 28 blowout port 29 auxiliary heater 30 merchandise display shelf A, B cooling Coil ML Main liquid valve MG Main gas valve MV Main valve CPV Capacity adjusting valve Off valve BA, BB bypass valve SA, SB suction valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F25B 47/02 560 F25B 47/02 560

Claims (2)

[Claims] 1. A refrigerating machine comprising a compressor, a condenser and a liquid receiver, one end of which is connected to a liquid refrigerant outlet of the liquid receiver and one end of which is connected to a suction side of the compressor. A plurality of showcases each provided with an expansion valve and a cooling coil in a refrigerant pipe from the refrigerant inlet to the same outlet are connected in parallel with the other end of the refrigerant return pipe, and the refrigerant forward pipe is connected to the refrigerant outgoing pipe during cooling operation. Is opened but closed at the start of the defrosting operation, and provided with a main liquid valve which is opened when defrosting of the cooling coil in any one of the plurality of showcases is completed, and A gas refrigerant outlet facing the gas phase of the receiver is provided, and the other end of the gas feed pipe having one end connected to the outlet is connected to the downstream side of the main liquid valve in the refrigerant forward pipe. At the time of cooling operation, it is closed, but it is opened at the start of defrosting operation. A main gas valve that is closed when the defrosting of the cooling coil in any one of the plurality of showcases is completed is provided, and a refrigerant pipe upstream of the expansion valve of each of the showcases is provided with a cooling valve during cooling operation. Is opened and closed appropriately according to the temperature in the showcase, but is closed at the start of the defrosting operation, and is provided with a main valve which is opened when the defrosting of the cooling coil in the showcase is completed. The other end of the bypass pipe, one end of which is connected to the inlet of the cooling coil, is connected to this bypass pipe,
A cooling device for a plurality of showcases, which is provided with a bypass valve which is closed during a cooling operation but is opened at the start of a defrosting operation and is closed when defrosting of a cooling coil in the showcase is completed. 2. A refrigerating machine comprising a compressor, a condenser and a liquid receiver, one end of which is connected to a liquid refrigerant outlet of the liquid receiver and one end of which is connected to a suction side of the compressor. A plurality of showcases each provided with an expansion valve and a cooling coil in a refrigerant pipe from the refrigerant inlet to the same outlet are connected in parallel with the other end of the refrigerant return pipe, and the refrigerant forward pipe is connected to the refrigerant outgoing pipe during cooling operation. Is opened but closed at the start of the defrosting operation, and provided with a main liquid valve which is opened when defrosting of the cooling coil in any one of the plurality of showcases is completed, and A gas refrigerant outlet facing the gas phase of the receiver is provided, and the other end of the gas feed pipe having one end connected to the outlet is connected to the downstream side of the main liquid valve in the refrigerant forward pipe. At the time of cooling operation, it is closed, but it is opened at the start of defrosting operation. A main gas valve that is closed when the defrosting of the cooling coil in any one of the plurality of showcases is completed is provided, and a refrigerant pipe upstream of the expansion valve of each of the showcases is provided with a cooling valve during cooling operation. Is opened and closed appropriately according to the temperature in the showcase, but is closed at the start of the defrosting operation, and is provided with a main valve which is opened when the defrosting of the cooling coil in the showcase is completed. The other end of the bypass pipe, one end of which is connected to the inlet of the cooling coil, is connected to this bypass pipe,
A bypass valve that is closed during the cooling operation but is opened at the start of the defrosting operation and is closed when the defrosting of the cooling coil in the showcase is completed. A start command is issued to the refrigerator and each showcase, and when defrosting of each showcase is completed and the outlet pipe temperature of the cooling coil reaches a predetermined temperature, defrosting is returned to the refrigerator and the showcase where the defrosting is completed. Equipped with a control device that issues commands,
When a defrost start command is issued from the control device, the main liquid valve in the refrigerator and the main valve of each showcase are closed, and the main gas valve of the refrigerator and the bypass valve of each showcase are opened and all The gas refrigerant from the receiver is supplied to the cooling coil of the showcase to perform defrosting by the latent heat of the gas refrigerant, and when a defrost return command is issued, the main liquid valve of the refrigerator is opened and the main refrigerant valve is opened. When the gas valve is closed and liquid refrigerant is supplied from the refrigerator to all the showcases, and in the showcase where defrosting has not been completed, the main valve is closed and the bypass valve is opened while the bypass pipe is connected to the cooling coil. Liquid refrigerant is supplied from the refrigeration unit to perform defrost by the sensible heat of the liquid refrigerant. In the showcase where the defrost is completed, the main valve is opened and the bypass valve is closed. The cooling operation Te is made the cooling device of the plurality showcase characterized.