KR20090009315A - Freezing device - Google Patents

Abstract

In a refrigerant circuit (20), an air conditioner unit (12), a refrigerating showcase (13), and a freezing showcase (14) are parallelly connected to an outdoor unit (11). To set an indoor heat exchanger (71) of the air conditioner unit (12) to a thermo-off state, opening degree control means (101) totally closes an indoor expansion valve (72). After that, the opening degree control means (101) detects the amount of refrigerant staying in the indoor heat exchanger (71) and adjusts the degree of opening of the indoor expansion valve (72) according to the amount of refrigerant.

Description

Freezer {FREEZING DEVICE}

The present invention relates to a refrigerating device having a plurality of use units, and more particularly, to a measure of high lease of refrigerant in a heat exchanger in a paused state.

Background Art Conventionally, a refrigerating device that circulates a refrigerant to perform a refrigerating cycle has been widely applied to air conditioners and the like. As this type of refrigeration apparatus, a so-called multi-type refrigeration apparatus is known, in which a plurality of use side units are connected in parallel to the heat source side unit.

For example, the refrigeration apparatus of patent document 1 (Unexamined-Japanese-Patent No. 8-159590) consists of one heat source side unit which has a compressor and a heat source side heat exchanger, and a utilization side heat exchanger (heating heat exchanger) and an expansion valve, respectively. Two use side units having:

The refrigerating device is configured to enable individual heating operation in each use side heat exchanger by opening each expansion valve to a predetermined opening degree. Specifically, for example, when heating operation is performed by two use side units at the same time, both expansion valves are opened and the refrigerant is supplied to both use side heat exchangers. As a result, heat is discharged from the refrigerant flowing through each utilization side heat exchanger to the indoor air, and heating is performed at each utilization side heat exchanger. As a result, the room corresponding to each utilization side heat exchanger is heated, respectively. On the other hand, for example, when the heating operation is performed by only one use side unit, the expansion valve corresponding to the kill use side unit is opened while the expansion valve corresponding to the use side unit to be temporarily stopped is closed. As a result, the refrigerant is supplied only to the use side unit on the operation side, and the room is heated only by this use side heat exchanger.

[Initiation of invention]

[Problem to Solve Invention]

However, as described above, when the expansion valve is closed in order to put one of the use side units into a pause state (so-called thermo-off state), the refrigerant is condensed in the use side heat exchanger in the pause state, and the liquid refrigerant after condensation The phenomenon which gradually accumulates in the utilization side heat exchanger (so-called accumulation of refrigerant) may occur. In this way, when a large amount of refrigerant accumulates in the use side heat exchanger, the amount of refrigerant to be supplied to the other use side unit is insufficient, resulting in a decrease in the cooling capacity and the heating capacity.

This invention is made | formed in view of this point, and the objective is to reliably prevent the refrigerant accumulation in the utilization-side heat exchanger which became the pause state.

[Means for solving the problem]

In the first invention, a plurality of use side units (12, 13, 14) are connected in parallel to a heat source side unit (11) having a compressor (41, 42) and a heat source side heat exchanger (44). At least one of the plurality of utilization side units (12, 13, 14) includes a heat exchanger (71) capable of a heating operation for releasing heat from a refrigerant, and the heat exchanger (71). It is assumed that the refrigerating device is provided with an expansion valve 72 corresponding to). The refrigerating device has a first control operation of tightening the opening degree of the expansion valve 72 to the fully closed or the micro-opening state when the heating heat exchanger 71 is in a pause state, and the first control operation is terminated. And an opening degree control means 101 for performing a second control operation for adjusting the opening degree of the expansion valve 72 based on the indicator indicating the amount of refrigerant accumulated in the heating heat exchanger 71 afterwards.

In the first invention, a plurality of use side units 12, 13, 14 are connected in parallel to the heat source side unit 11, so that a so-called multi-type refrigeration apparatus is constituted. In the refrigerant circuit 20 of this refrigerating device, the refrigerant is circulated to achieve a vapor compression refrigeration cycle. When the refrigerant is supplied to each of the use side units 12, 13 and 14, respectively, the refrigerant is evaporated or condensed at each of the use side units 12, 13 and 14, and by these use side units 12, 13 and 14, respectively. For example, the heating or cooling of a room or the cooling in a storage room is done individually.

Here, in the present invention, when the heating heat exchanger 71 capable of heating operation for releasing heat from the refrigerant is temporarily stopped, the opening degree control means 101 first executes the first control operation. In this first control operation, the expansion valve 72 corresponding to the heating heat exchanger 71 is tightened to the full open or near the small open degree. As a result, since almost no refrigerant is supplied to the heat exchanger 71, the heating operation is not performed in the heat exchanger 71. On the other hand, when the expansion valve 72 is tightened in this way, the refrigerant in the heat exchanger 71 gradually condenses, and the liquid refrigerant accumulates in the heat exchanger 71. As a result, in the heat-exchanging heat exchanger 71 in the paused state, accumulation of refrigerant occurs.

Therefore, the opening degree control means 101 of this invention performs a 2nd control operation after prevention of the accumulation of refrigerant | coolant in the heat exchanger 71 after completion | finish of the said 1st control operation. In this second control operation, an index indicating the amount of refrigerant accumulated in the heat exchanger 71 is detected by a predetermined method. The opening degree of the expansion valve 72 is appropriately adjusted based on this index. Specifically, when the refrigerant condensed in the heating heat exchanger 71 accumulates after the end of the first control operation and the indicator indicating the amount of refrigerant accumulated in the heating heat exchanger 71 increases, the opening degree control means 101 expands the expansion valve 72. Increase the degree of openness. As a result, the refrigerant accumulated in the heat exchanger (71) passes through the expansion valve (72) and is discharged to the outside of the use side unit (12).

On the other hand, after the coolant pool in the heating heat exchanger 71 is removed in this manner, if the opening degree of the expansion valve 72 is increased, more refrigerant than necessary is supplied toward the heating heat exchanger 71, and other uses are made. The cooling capacity and heating capacity of the side units 13 and 14 tend to be insufficient. Therefore, in this second control operation, when the refrigerant pool in the heat exchanger 71 is eliminated and the aforementioned indicator becomes small, the opening degree control means 101 quickly decreases the opening degree of the expansion valve 72. As a result, the amount of refrigerant supplied into the heating heat exchanger 71 is reduced, so that much refrigerant is supplied to the other using side units 13 and 14 by that amount.

According to a second aspect of the present invention, in the refrigerating device of the first aspect of the invention, the first control operation of the opening degree control means (101) is an operation of closing the expansion valve (72).

In the second aspect of the invention, when the operation for temporarily stopping the heat exchanger 71 is performed, the opening degree control means 101 performs a first control operation in which the expansion valve 72 is fully closed. As a result, since no coolant flows to the use side unit 12 on which the heat exchanger 71 is disposed, much coolant is supplied to the other use side units 13 and 14 by that amount.

In the 3rd invention, in the refrigerating apparatus of 1st or 2nd invention, in the 2nd control operation of the said opening degree control means 101, it is an index which shows the amount of refrigerant accumulated in the heat exchanger 71, The said heat exchanger The subcooling degree of the refrigerant | coolant of the inlet side of 71 or the refrigerant subcooling degree in this heating heat exchanger 71 is used.

In the third invention, the subcooling degree is used as an index indicating the amount of refrigerant accumulated in the heat exchanger 71. That is, when the refrigerant is condensed in the heating heat exchanger 71 in the paused state and the liquid refrigerant accumulates in the heating heat exchanger 71, the liquid refrigerant is radiated again to become a supercooled state. Thereby, by detecting the coolant subcooling degree in the heat exchanger 71, the amount of refrigerant accumulated in this heat exchanger 71 can be grasped. In the case where the liquid refrigerant completely accumulates in the heat exchanger 71, the refrigerant may condense even in the vicinity of the inlet of the heat exchanger 71, resulting in a supercooled state. Therefore, the amount of refrigerant accumulated in the heat exchanger 71 can be grasped by detecting the supercooling degree of the refrigerant at the inlet side of the heat exchanger 71.

In the fourth invention, in the refrigerating device of the third invention, in the second control operation of the opening degree control means 101, when the expansion valve 72 remains closed for a predetermined time or more, the expansion valve 72 ) Is forcibly opened to a predetermined opening.

In the fourth invention, although the opening degree control means 101 during the second control operation controls the opening degree of the expansion valve 72 based on the supercooling degree of the refrigerant, the expansion valve 72 remains closed. In this case, the expansion valve 72 is forcibly opened.

By the way, when detecting the supercooling degree of the inlet side or internal refrigerant | coolant of the heating heat exchanger 71 like the above-mentioned 3rd invention, it is influenced by the ambient temperature of the heating heat exchanger 71, and is in the heating heat exchanger 71 It may not be possible to accurately determine the amount of refrigerant. Specifically, for example, when the equivalent saturation temperature Pc of the high-pressure gas and the refrigerant temperature Th1 at the inlet side of the heat exchanger 71 are detected by a predetermined sensor, and the subcooling degree is calculated from this temperature difference, the heat exchanger When the ambient temperature of the machine 71 becomes a relatively high temperature, the temperature Th1 detected by the sensor tends to be high. Therefore, under such conditions, even though a large amount of refrigerant is actually accumulated in the heat exchanger 71, the supercooling degree of the refrigerant detected by the sensor is reduced. As a result, there is a fear that the expansion valve 72 will remain in a fully closed state.

Thus, in the fourth aspect of the present invention, when the expansion valve 72 continues to be closed for a predetermined time or more during the second control operation, the expansion valve 72 is forcibly opened. Here, it is preferable that the opening degree of the expansion valve 72 at this time is a very small opening degree. By opening the expansion valve 72 in this way, even if the subcooling degree Pc-Th1 of the refrigerant is detected with a small value under the influence of the ambient temperature, the refrigerant pool in the heat exchanger 71 is reliably eliminated.

When the expansion valve 72 is forcibly opened in this manner and then the opening degree of the expansion valve 72 is adjusted again by the opening degree control means 101, the amount of refrigerant in the heat exchanger 71 is accurately detected. Easier That is, when the expansion valve 72 is forcibly opened, since the refrigerant is continuously supplied into the heat exchanger 71, the refrigerant flowing through the heat exchanger 71 becomes less affected by the ambient temperature. Thereby, although the coolant accumulates in the heat exchanger 71 as described above, it is avoided that the supercooling degree of the coolant is calculated to be a small value. Therefore, after forcibly opening the expansion valve 72, the amount of refrigerant in the heating heat exchanger 71 can be accurately detected, and the opening degree of the expansion valve 72 can be adjusted appropriately.

In the fifth aspect of the invention, in the refrigerating device of the first invention, a cooling operation in which a refrigerant absorbs heat from air is used in the use side unit (12) and the other use side units (13, 14) in which the heating heat exchanger (71) is disposed. These cooling heat exchangers 81 and 91 are arranged, and the refrigerant circuit 20 includes the cooling heat exchanger 81 after the discharge refrigerant of the compressors 41 and 42 radiates heat from the heating heat exchanger 71. , And the heat recovery operation sucked into the compressors 41 and 42 after endotherm is possible. During the second control operation of the opening degree control means 101, the amount of refrigerant accumulated in the heating heat exchanger 71 is increased. It is characterized in that it is provided with operation control means 102 which temporarily executes the said heat recovery operation, when the indicator shown exceeds the prescribed value continuously for more than predetermined time.

In the fifth aspect of the invention, the cooling heat exchangers 81 and 91 are disposed in the use side units 13 and 14 other than the use side unit 12 in which the heating heat exchanger 71 is disposed. The cooling heat exchangers (81, 91) cool the inside of the reservoir by cooling the refrigerant with air. In the refrigerant circuit 20 of the refrigerating device, the discharge refrigerant of the compressors 41 and 42 is supplied in the order of the heat exchanger 71 and the cooling heat exchangers 81 and 91 to be recovered to the suction side of the compressors 41 and 42. The heat recovery operation is configured to be possible. That is, in this heat recovery operation, the discharged refrigerant of the compressors 41 and 42 is not sent to the heat source side heat exchanger 44 of the heat source side unit 11, and the discharged refrigerant is condensed by the heat exchanger 71. After the condensed refrigerant is depressurized by the expansion valve 72, a refrigeration cycle is performed in which the cooling heat exchangers 81 and 91 evaporate.

Here, the operation control means 102 of the present invention, when the second control operation by the opening degree control means 101 still does not resolve the refrigerant pool in the heat exchanger 71, the refrigerant circuit ( In step 20), the heat recovery operation is forcibly executed. As a result, since the coolant is actively supplied into the heat exchanger 71, the coolant pool in the heat exchanger 71 is reliably eliminated. At the same time, the refrigerant flowing out of the heating heat exchanger 71 and flowing through the cooling heat exchangers 81 and 91 is used for the cooling operation of the cooling heat exchangers 81 and 91.

[Effects of the Invention]

In 1st invention, when the operation | movement which pauses the heat exchanger 71 is performed, after tightening the opening degree of the expansion valve 72 by a 1st control operation | movement, it shows the amount of refrigerant accumulated in this heat exchanger 71. A second control operation for adjusting the opening degree of the expansion valve 72 is performed based on the indicator. Thus, according to the present invention, the opening of the expansion valve 72 is increased by detecting the refrigerant pool in the heating heat exchanger 71, and the refrigerant accumulated in the heating heat exchanger 71 is transferred to the other using side units 13 and 14. Can be sent to That is, according to the present invention, it is possible to reliably solve the refrigerant pool in the heat exchanger 71 in the pause state, thereby avoiding the deterioration of the capacity of the other utilization side units 13 and 14 in advance.

Moreover, according to this invention, when the amount of refrigerant | coolant which accumulated in the heating heat exchanger 71 is small, the opening degree of the expansion valve 72 can be made small. Thus, even though the refrigerant pool in the heat exchanger 71 has already been eliminated, the refrigerant is not excessively supplied to the heat exchanger 71, so that the amount of refrigerant to be sent to the other utilization side units 13 and 14 can be sufficiently secured. Can be. Therefore, the fall of the capability of the other utilization side units 13 and 14 can be more effectively avoided.

In the second aspect of the invention, when the heating heat exchanger 71 is temporarily stopped, the first control operation for bringing the expansion valve 72 into the closed state is performed. Thereby, according to this invention, the amount of refrigerant sent to the other utilization side units 13 and 14 can be made larger, and the capability of these utilization side units 13 and 14 can be improved.

Further, in the third invention, the amount of refrigerant accumulated in the heat exchanger (71) is detected by using the supercooling degree of the inlet side of the heat exchanger (71) or the refrigerant inside the heat exchanger (71) during the second control operation. Do it. Thus, according to the present invention, it is possible to easily grasp the refrigerant pool in the heat exchanger 71 using a temperature sensor, a pressure sensor, or the like disposed in the refrigerant circuit 20.

In the fourth aspect of the present invention, when the expansion valve 72 is continuously closed for a predetermined time or more during the second control operation in consideration of the fact that the supercooling degree of the refrigerant decreases under the influence of the ambient temperature of the heat exchanger 71. The expansion valve 72 is opened. As a result, according to the present invention, in spite of the fact that the refrigerant is accumulated in the heat exchanger 71, the expansion valve 72 can be prevented from being kept closed, so that the heat exchanger 71 can be avoided. Of refrigerant can be reliably eliminated.

In the fourth aspect of the present invention, after the expansion valve 72 is opened to supply the refrigerant into the heat exchanger 71, the opening degree of the expansion valve 72 can be controlled again according to the degree of supercooling of the refrigerant. In this way, since the temperature of the refrigerant flowing in the inlet side or the inside of the heat exchanger 71 is less affected by the temperature around the heat exchanger 71, the amount of refrigerant in the heat exchanger 71 can be accurately detected. . Thereby, according to this invention, the opening degree of the expansion valve 72 can be appropriately controlled according to the amount of refrigerant accumulated in the heat exchanger 71. Therefore, it is possible to reliably eliminate the refrigerant accumulation in the heat exchanger 71 and to ensure a sufficient amount of the refrigerant to be sent to the other utilization side units 13 and 14.

In the fifth aspect of the present invention, the heat recovery operation is performed in the refrigerant circuit 20 when the refrigerant pool in the heat exchanger 71 is not eliminated even when the second control operation by the opening degree control means 101 is performed. . Therefore, according to the present invention, by supplying the refrigerant into the heat exchanger 71, the refrigerant pool in the heat exchanger 71 can be eliminated. At this time, in the present invention, the discharge refrigerant of the compressors 41 and 42 is not supplied to the heat source side heat exchanger 44 or the like, but is actively supplied into the heat exchanger 71. Therefore, according to the present invention, the refrigerant in the heat exchanger 71 can be reliably discharged to the outside.

In this heat recovery operation, the refrigerant is evaporated in the cooling heat exchangers 81 and 91 while discharging the accumulated refrigerant in the heating heat exchanger 71. That is, according to the present invention, it is possible to reliably solve the refrigerant pool in the heat exchanger 71 without temporarily stopping the cooling operation by the cooling heat exchangers 81 and 91.

1 is a circuit diagram of a refrigerant circuit of a refrigerating device according to one embodiment.

2 is a piping system diagram showing the flow of the refrigerant during the cooling operation.

3 is a piping system diagram showing the refrigerant flow in the heating operation.

4 is a piping system diagram showing the flow of the refrigerant immediately after the pause operation of the indoor heat exchanger.

5 is a flowchart showing a second control operation by the opening degree control means.

6 is a flowchart showing the control operation of the operation control means.

7 is a piping system diagram showing the flow of the refrigerant during the heat recovery operation.

[Description of the code]

10: refrigeration unit 12: air conditioning unit (use side unit)

13: refrigerated showcase (use side unit) 14: refrigerated showcase (use side unit)

20: refrigerant circuit 41: first compressor

42: second compressor 71: indoor heat exchanger (heating heat exchanger)

72: expansion valve (expansion valve) 81: refrigeration heat exchanger (cooling heat exchanger)

91: refrigeration heat exchanger (cooling heat exchanger) 101: opening degree control means

102: operation control means

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail based on drawing.

The refrigeration apparatus 10 which concerns on this embodiment is installed in a convenience store etc., and performs cooling and indoor air conditioning of a refrigerator and a freezer simultaneously.

As shown in FIG. 1, the refrigerating device 10 includes an outdoor unit 11, an air conditioning unit 12, a refrigerated showcase 13, and a refrigerated showcase 14. In the outdoor unit 11, an outdoor circuit 40 constituting the heat source side circuit is disposed. The air conditioning unit 12 is provided with an air conditioning circuit 70 constituting the first use-side circuit. In the refrigerator case 13, the refrigerator circuit 80 which comprises a 2nd utilization side circuit is arrange | positioned. In the freezing showcase 14, a freezing circuit 90 constituting the third use-side circuit is disposed. In the refrigerating device 10, a plurality of use side circuits 70, 80, and 90 are connected in parallel to the outdoor circuit 40 to form a refrigerant circuit 20 for performing a vapor compression refrigeration cycle.

The outdoor circuit 40 and the respective use side circuits 70, 80, and 90 are connected to each other by the liquid side connection pipe 31, the first gas side connection pipe 32, and the second gas side connection pipe 33. One end of the liquid side connecting pipe 31 is connected to the liquid side closing valve 21 of the outdoor circuit 40. The other end side of the liquid side connection pipe 31 is branched into three of the first liquid distributor engine 31a, the second liquid distributor engine 31b, and the third liquid distributor engine 31c, and the first liquid distributor engine 31a is air-conditioned. At 70, the second liquid distributor engine 31b is connected to the refrigerating circuit 80, and the third liquid distributor engine 31c is connected to the refrigerating circuit 90, respectively. One end of the first gas side connecting pipe 32 is connected to the first gas side closing valve 22 of the outdoor circuit 40, and the other end thereof is connected to the air conditioning circuit 70. One end of the second gas side connecting pipe 33 is connected to the second gas side closing valve 23 of the outdoor circuit 40. The other end side of the second gas side connecting pipe 33 is branched into two, the first gas branch pipe 33a and the second gas branch pipe 33b, and the first gas branch pipe 33a is refrigerated circuit 80. The second gas distributor 33b is connected to the refrigerating circuit 90, respectively.

<Outdoor unit>

The outdoor circuit 40 of the outdoor unit 11 includes three compressors 41, 42, and 43, the first to third compressors, the outdoor heat exchanger 44, the receiver 45, and the outdoor expansion valve ( 46, and first to third four-way valves 47, 48, 49 are arranged.

The first to third compressors 41, 42, 43 are constituted by a high pressure dome type scroll compressor. The first compressor 41 constitutes a variable displacement compressor. That is, the first compressor 41 is configured to have a variable rotational speed by inverter control. On the other hand, the second compressor 42 and the third compressor 43 constitute a fixed displacement compressor having a constant rotation speed.

One end of the first suction pipe 51 is connected to the suction side of the first compressor 41. The other end of the first suction pipe 51 is connected to the second gas side closing valve 23. One end of the second suction pipe 52 is connected to the suction side of the second compressor 42. The other end of the second suction pipe 52 is connected to the third crossover switching valve 49. One end of the third suction pipe 53 is connected to the suction side of the third compressor 43. The other end of the third suction pipe 53 is connected to the second cross switching valve 48.

The first discharge pipe 54 is connected to the discharge side of the first compressor 41. The other end of the first discharge pipe 54 is connected to the first cross switching valve 47 via the discharge pipe 57. The second discharge pipe 55 is connected to the discharge side of the second compressor 42. The other end of the second discharge pipe 55 is connected to the discharge pipe 57. The third discharge pipe 56 is connected to the discharge side of the third compressor 43. The other end of the third discharge pipe 56 is connected in the middle of the discharge pipe 57.

The outdoor heat exchanger (44) is a cross fin fin tube type heat exchanger, and constitutes a heat source side heat exchanger. The outdoor fan 50 is disposed near the outdoor heat exchanger 44. In the outdoor heat exchanger (44), heat exchange is performed between the outdoor air and the refrigerant blown by the outdoor fan (50). One end of the outdoor heat exchanger 44 is connected to the first cross switching valve 47. The other end of the outdoor heat exchanger 44 is connected to the top of the receiver 45 via the first liquid pipe 58. The bottom of the receiver 45 is connected to the liquid side closing valve 21 via the second liquid pipe 59.

In the middle of the first liquid pipe 58, one end of the first bypass pipe 60 and the second bypass pipe 61 are connected to each other. The other ends of the first bypass pipe 60 and the second bypass pipe 61 are connected to the second liquid pipe 59, respectively. The outdoor expansion valve 46 is disposed in the first bypass pipe 60. The outdoor expansion valve 46 is constituted by an electromagnetic expansion valve whose opening degree is adjustable. One end of the liquid injection pipe 62 is connected in the middle of the second bypass pipe 61. The other end of the liquid injection pipe 62 is connected in the middle of the first suction pipe 51. Moreover, the flow control valve 63 which can adjust an opening degree is arrange | positioned in the liquid injection pipe | tube 62.

Each of the first to third crossover switching valves 47, 48, and 49 has first to fourth ports, respectively. In the first four-way valve 47, the first port is connected to the discharge pipe 57, the second port is connected to the fourth port of the second four way switch valve 48, and the third port is connected to the outdoor heat exchanger 44. And a fourth port are connected to the first gas side closing valve 22, respectively. In the second turns valve 48, the first port is connected to the third discharge pipe 56 and the second port is connected to the third suction pipe 53, respectively, while the third port is closed. In the third four-way valve 49, the first port is closed, while the second port is the second suction pipe 52, the third port is the third suction pipe 53, and the fourth port is the first suction pipe ( 51) respectively.

Each of the four-way switching valves 47, 48, and 49 has a first state (state shown by a solid line in FIG. 1) in which the first port and the third port communicate with each other, and the second port and the fourth port communicate with each other, The first port and the fourth port communicate with each other, and the second port and the third port communicate with each other.

Various sensors and pressure switches are also disposed in the outdoor circuit 40. Specifically, the first suction pipe 51, the first suction temperature sensor 111 and the first suction pressure sensor 112, the third suction pipe 53, the second suction temperature sensor 113 and the second suction pressure sensor. 114 are disposed respectively. The first high pressure switch 115 is provided in the first discharge pipe 54, the second high pressure pressure switch 116 is provided in the second discharge pipe 55, and the third high pressure pressure switch 3 is provided in the third discharge pipe 56. 117 are disposed respectively. The first discharge temperature sensor 118 and the first discharge pressure sensor 119 are disposed in the discharge pipe 57, and the second discharge temperature sensor 120 is disposed in the third discharge pipe 56, respectively. In the outdoor heat exchanger (44), an outdoor refrigerant temperature sensor (121) is disposed in the heat transfer pipe. In addition, the outdoor temperature sensor 122 is disposed near the outdoor heat exchanger 44.

Further, the outdoor circuit 40 is also provided with a plurality of check valves which allow the circulation of the refrigerant in one direction and prohibit the distribution of the refrigerant in the opposite direction to this direction. Specifically, the check valve CV-1 is provided in the pipe between the first suction pipe 51 and the second suction pipe 52, and the check valve CV is provided in the pipe between the second suction pipe 52 and the third suction pipe 53. -2) are disposed respectively. In addition, the check valve CV-3 is disposed in the second discharge pipe 55, and the check valve CV-4 is disposed in the third discharge pipe 56. A check valve CV-5 is provided in the first liquid pipe 58, a check valve CV-6 is provided in the second liquid pipe 59, and a check valve CV-7 is provided in the second bypass pipe 61, respectively. Is placed. Here, these check valves CV-1, CV-2, ... are configured to allow only refrigerant flow in the direction of the arrow attached to the symbol showing the check valve of FIG.

<Air conditioning unit>

An indoor heat exchanger 71 and an indoor expansion valve 72 are disposed in the air conditioning circuit 70 of the air conditioning unit 12. The indoor heat exchanger 71 is a cross fin type fin tube heat exchanger, and constitutes a first use-side heat exchanger. In addition, the indoor heat exchanger 71 constitutes a heating heat exchanger capable of a heating operation for releasing heat from the refrigerant. An indoor fan 73 is disposed near the indoor heat exchanger 71. In this indoor heat exchanger (71), heat exchange is performed between the indoor air and the refrigerant blown by the indoor fan (73). The indoor expansion valve 72 is composed of an electromagnetic expansion valve whose opening degree is adjustable by a pulse motor.

In the air conditioning circuit 70, the first refrigerant temperature sensor 123 is connected to the pipe between the first gas side connecting pipe 32 and the indoor heat exchanger 71, and the second refrigerant temperature is supplied to the heat transfer tube of the indoor heat exchanger 71. Sensors 124 are disposed respectively. In addition, the indoor temperature sensor 125 is disposed near the indoor heat exchanger 71.

<Cold Showcase>

In the refrigerating circuit 80 of the refrigerating showcase 13, a refrigerating heat exchanger 81 and a refrigerating expansion valve 82 are arranged. The refrigeration heat exchanger (81) is a cross fin fin tube type heat exchanger and constitutes a second use-side heat exchanger. In addition, the refrigerating heat exchanger 81 constitutes a cooling heat exchanger in which the refrigerant absorbs heat from the air and cools the inside of the reservoir. In the vicinity of the refrigeration heat exchanger (81), a refrigeration fan (83) is arranged. In the refrigerating heat exchanger (81), heat exchange is performed between the refrigerant in the reservoir and the air blown by the refrigerating fan (83).

In the refrigerating circuit 80, the first outlet refrigerant temperature sensor 126 is disposed on the outlet side of the refrigerating heat exchanger 81. The refrigerating expansion valve 82 is configured as a thermostatic expansion valve whose opening degree is adjusted according to the detection temperature of the first outlet refrigerant temperature sensor 126. In the vicinity of the upstream side of the refrigeration expansion valve 82, the 1st solenoid valve SV-1 which opens and closes is opened. In the vicinity of the refrigerating heat exchanger (81), a temperature sensor (127) in the first reservoir for detecting the temperature of the air in the reservoir in the refrigerating showcase (13) is arranged.

<Frozen showcase>

In the freezing circuit 90 of the freezing showcase 14, a freezing heat exchanger 91, a freezing expansion valve 92, and a booster compressor 94 are arranged. The refrigeration heat exchanger (91) is a cross fin type fin tube heat exchanger and constitutes a third use-side heat exchanger. The refrigeration heat exchanger 91 constitutes a cooling heat exchanger in which the refrigerant absorbs heat from the air and cools the inside of the reservoir. A refrigeration fan 93 is disposed near the refrigeration heat exchanger 91. In this refrigeration heat exchanger (91), heat exchange is performed between the refrigerant and the air in the reservoir through which the refrigeration fan (93) blows.

In the refrigerating circuit 90, a second outlet refrigerant temperature sensor 128 is disposed on the outlet side of the refrigerating heat exchanger 91. The refrigeration expansion valve 92 is composed of a thermostatic expansion valve whose opening degree is adjusted according to the detection temperature of the second outlet refrigerant temperature sensor 128. In the vicinity of the upstream side of the refrigeration expansion valve 92, a second solenoid valve SV-2 having a free opening and closing is arranged. In the vicinity of the freezing heat exchanger 91, a second temperature sensor 129 in the second reservoir for detecting the temperature of the air in the storage in the freezing showcase 14 is arranged.

The booster compressor 94 is a high pressure dome scroll compressor and constitutes a variable displacement compressor. The fourth suction pipe 95 is connected to the suction side of the booster compressor 94, and the fourth discharge pipe 96 is connected to the discharge side. In the fourth discharge pipe 96, a fourth high pressure switch 130, an oil separator 97, and a check valve CV-8 are disposed. The oil separator 97 is connected to an oil return pipe 98 for recovering the refrigeration oil separated from the refrigerant to the suction side of the booster compressor 94. A capillary tube 98a is disposed in the oil return tube 98.

In the refrigerating circuit 90, a third bypass pipe 99 is also arranged to connect the fourth suction pipe 95 and the fourth discharge pipe 96. The check valve CV-9 is disposed in the third bypass pipe 99. The third bypass pipe 99 is configured to send the refrigerant flowing through the fourth suction pipe 95 to the fourth discharge pipe 96 by bypassing the booster compressor 94 when the booster compressor 94 fails.

<Controller>

In the refrigerating device 10, a controller 100 for controlling each control target device arranged in the refrigerant circuit 20 is disposed. The controller 100 is configured to receive a signal of each sensor arranged in the refrigerant circuit 20. The controller 100 performs operation control of each compressor, switching control of each of the four-way switching valves, and the like in accordance with the signals of these sensors.

In addition, the controller 100 is provided with an opening degree control means 101 and an operation control means 102 which are features of the present invention. The opening degree control means 101 and the operation control means 102 constitute means for preventing the refrigerant from accumulating in the indoor heat exchanger 71 when the heating operation of the indoor heat exchanger 71 is temporarily stopped. The details of the control operation by these opening degree control means 101 and the operation control means 102 will be described later.

Operation operation

Next, the operation | movement operation of the refrigerating device 10 which concerns on this embodiment is demonstrated. In the refrigerating device 10, a cooling operation for cooling the room with the air conditioning unit 12 while cooling the inside of the storage cabinets 13 and 14, and cooling the inside of the storage cabinets 13 and 14, The air conditioning unit 12 is configured to enable the heating operation of heating the room.

<Cooling operation>

A typical cooling operation of the refrigerating device 10 will be described with reference to FIG. 2.

In the cooling operation of this example, the first four-way switching valve 47, the second four-way switching valve 48, and the third four-way switching valve 49 are set to the first state. In addition, the outdoor expansion valve 46 and the flow regulating valve 63 are fully closed, and the first solenoid valve SV-1 and the second solenoid valve SV-2 are open. And the opening degree of the indoor expansion valve 72, the refrigeration expansion valve 82, and the refrigeration expansion valve 92 is adjusted suitably, respectively. In addition, the fans 50, 73, 83, 93, the first to third compressors 41, 42, 43 and the booster compressor 94 are in an operating state, respectively.

The refrigerant compressed by the first to third compressors 41, 42, and 43 joins the discharge pipe 57, and then flows through the first crossover valve 47 to the outdoor heat exchanger 44. In the outdoor heat exchanger (44), the refrigerant radiates heat to the outdoor air to condense. The refrigerant condensed in the outdoor heat exchanger 44 flows through the first liquid pipe 58, the receiver 45, and the second liquid pipe 59 in order to flow into the liquid side connection pipe 31. The refrigerant flowing into the liquid side connection pipe 31 flows branched into the first liquid distributor engine 31a, the second liquid distributor engine 31b, and the third liquid distributor engine 31c.

The refrigerant flowing into the first liquid distributor 31a is depressurized when passing through the indoor expansion valve 72 and then flows through the indoor heat exchanger 71. In the indoor heat exchanger (71), the refrigerant absorbs heat from the room air and evaporates. As a result, the room is cooled. The refrigerant evaporated in the indoor heat exchanger (71) flows in order through the first gas side connecting pipe (32), the first four-way switching valve (47), the second four-way switching valve (48), and the third suction pipe (53). It is sucked into the third compressor 43.

The refrigerant introduced into the second liquid distributor (31b) is depressurized when passing through the refrigeration expansion valve (82) and then flows through the refrigeration heat exchanger (81). In the refrigerating heat exchanger (81), the refrigerant absorbs heat from the air in the reservoir and evaporates. As a result, cooling in the storage of the refrigerating showcase 13 is achieved. In this refrigerated showcase 13, for example, the temperature in the reservoir is maintained at 5 ° C. The refrigerant evaporated in the refrigerating heat exchanger (81) flows into the first gas branch pipe (33a).

The refrigerant flowing into the third liquid distributor (31c) is depressurized when passing through the refrigeration expansion valve (92) and then flows through the refrigeration heat exchanger (91). In the freezer heat exchanger (91), the refrigerant absorbs heat from the air in the reservoir and evaporates. As a result, cooling in the storage of the freezing showcase 14 is achieved. In this freezing showcase 14, for example, the temperature in the reservoir is maintained at -10 ° C. The refrigerant evaporated in the freezer heat exchanger (91) is compressed in the booster compressor (94) and then flows into the second gas distributor (33b).

The refrigerant joined in the second gas side connecting pipe 33 flows again into the first suction pipe 51 and the second suction pipe 52, and then flows into the first compressor 41 and the second compressor 42, respectively. Is inhaled.

<Heating operation>

A typical heating operation of the refrigerating device 10 will be described with reference to FIG. 3.

In the heating operation of this example, the first four-way switching valve 47 and the second four-way switching valve 48 are set to the second state, and the third four-way switching valve 49 is set to the first state. In addition, the outdoor expansion valve 46 and the flow regulating valve 63 are fully closed, and the first solenoid valve SV-1 and the second solenoid valve SV-2 are open. And the opening degree of the indoor expansion valve 72, the refrigeration expansion valve 82, and the refrigeration expansion valve 92 is adjusted suitably, respectively. In addition, each of the fans 50, 73, 83, 93, the first compressor 41, the second compressor 42, and the booster compressor 94 are in an operating state, respectively.

The refrigerant compressed by the first compressor 41 and the second compressor 42, respectively, merges in the discharge pipe 57 and then branches into two again and flows. One refrigerant flows through the second crossover valve 48 to the outdoor heat exchanger 44 to condense, and then flows through the first liquid pipe 58, the receiver 45, and the second liquid pipe 59 in order to connect the liquid side. It flows into the pipe 31. The other refrigerant flows through the indoor heat exchanger 71 through the first four-way switching valve 47. In the indoor heat exchanger (71), the refrigerant radiates heat to the indoor air to condense. As a result, the room is heated. The refrigerant condensed in the indoor heat exchanger (71) is depressurized when passing through the indoor expansion valve (72), and then flows into the first liquid distributor (31a).

The refrigerant joined in the liquid side connection pipe 31 again branches to the second liquid distributor engine 31b and the third liquid distributor engine 31c and flows. The coolant flowing into the second liquid engine 31b is used for cooling in the storage of the refrigerating showcase 13 in the same manner as the cooling operation described above. In addition, the coolant flowing into the third liquid engine 31c is used for cooling in the storage of the freezing showcase 14 in the same manner as the cooling operation described above. The refrigerant used for cooling in the cabinets of the showcases 13 and 14 joins in the second gas side connecting pipe 33 and is then sucked into the first compressor 41 and the second compressor 42, respectively.

<Temporary operation of air conditioning unit during heating operation>

During the heating operation mentioned above, the heating operation by the indoor heat exchanger 71 may be unnecessary, for example, when the indoor temperature reaches the set temperature input by the user. Thus, in the refrigerating device 10, if a predetermined condition is established during the above-described heating operation, a first control operation (thermo off operation) is performed in which the indoor heat exchanger 71 is temporarily stopped.

Specifically, in the temporary stop operation of the indoor heat exchanger 71 during the heating operation, the opening degree control means 101 of the controller 100 tightens the opening degree of the indoor expansion valve 72 to make it totally closed. As a result, as shown in FIG. 4, the discharge refrigerant of the 1st compressor 41 and the 2nd compressor 42 is supplied toward the outdoor heat exchanger 44 substantially. The refrigerant after condensing in the outdoor heat exchanger 44 is supplied to each showcase 13 and 14 through the same flow path as the above-described heating operation and used for cooling in the storehouse of each showcase 13 and 14.

On the other hand, in the air conditioning unit 12, since the indoor expansion valve 72 is in a fully closed state, the refrigerant does not flow through the indoor heat exchanger 71. As a result, in the indoor heat exchanger 71, the refrigerant and the indoor air are not actively exchanged, and the indoor heat exchanger 71 is substantially in a pause state (thermo-off state). Thereafter, when predetermined conditions, such as a case where the room temperature becomes lower than the predetermined temperature by more than a predetermined temperature, are established, the indoor heat exchanger 71 is in a thermo state and the above-described heating operation is resumed.

<Opening control after pause operation>

However, in the temporary stop operation of the indoor heat exchanger 71 during the heating operation, as described above, the indoor expansion valve 72 is fully closed, but at this time, the gas side of the indoor heat exchanger 71 is connected to the circulation path of the refrigerant. Remain in communication. Therefore, after this pause operation, the refrigerant enters the indoor heat exchanger 71 and gradually condenses, and the liquid refrigerant after condensation gradually accumulates in the indoor heat exchanger 71. That is, there is a possibility that so-called refrigerant pooling may occur in the indoor heat exchanger 71 in the paused state. As the amount of refrigerant that accumulates in the indoor heat exchanger 71 increases, the amount of refrigerant supplied to each showcase 13 and 14 decreases, so that the cooling capacity of the refrigerating heat exchanger 81 or the freezing heat exchanger 91 is reduced. Causes a problem. Thus, the opening degree control means 101 of the present embodiment adjusts the opening degree of the indoor expansion valve 72 appropriately after the indoor expansion valve 72 is fully closed when the air conditioning unit 12 is temporarily stopped. By performing the opening degree control operation (second control operation), the refrigerant pool in the indoor heat exchanger 71 is eliminated.

As shown in Fig. 5, in the opening degree control operation, a determination is made whether or not a large amount of refrigerant is accumulated in the indoor heat exchanger 71 in step S1. Specifically, in step S1, the equivalent high saturation temperature Pc obtained from the detected values of the first discharge temperature sensor 118 or the first discharge pressure sensor 119 and the first refrigerant temperature sensor 123 are used. The temperature difference Pc-Th1 of the detected refrigerant temperature Th1 is calculated. That is, in step S1, the refrigerant subcooling degree Pc-Th1 near the inlet of the indoor heat exchanger 71 is calculated.

Here, when the indoor heat exchanger 71 is filled with liquid refrigerant, the refrigerant at the inlet side of the indoor heat exchanger 71 also becomes a supercooled state, so that the supercooling degree Pc-Th1 of the refrigerant also increases. That is, the supercooling degree Pc-Th1 of such a refrigerant | coolant becomes an index which shows the amount of refrigerant | coolant of the indoor heat exchanger 71. FIG. Therefore, in step S1, when this subcooling degree Pc-Th1 is larger than T1 degreeC (for example, 2 degreeC), it is determined that much refrigerant | coolant is accumulated in the indoor heat exchanger 71, and it goes to step S2. To fulfill. In step S2, the opening degree of the indoor expansion valve 72 in the current state is increased by a predetermined pulse (for example, 352 pulses). As a result, the refrigerant accumulated in the indoor heat exchanger (71) passes through the indoor expansion valve (72), flows through the first liquid distributor (31a), and is supplied to the showcases (13, 14).

On the other hand, when the refrigerant accumulated in the indoor heat exchanger 71 is discharged in this manner, the supercooling degree Pc-Th1 also gradually decreases. And in step S1, when the subcooling degree Pc-Th1 of this refrigerant | coolant becomes T1 degrees C or less, it will transfer to step S3 from step S1. In step S3, a confirmation determination is made as to whether or not the refrigerant pool in the indoor heat exchanger 71 has been released. Specifically, in step S3, when the supercooling degree Pc-Th1 of the inflow-side refrigerant of the indoor heat exchanger 71 continues to be T1 ° C or less for t1 minute (for example, 3 minutes), the indoor heat exchanger 71 It is determined that the coolant is hardly accumulated in the chamber, and the flow proceeds to step S4. As a result, the indoor expansion valve 72 is in a fully closed state.

Further, in step S3, the temperature difference Pc-Th2 between the high-pressure equivalent saturation temperature Pc and the coolant temperature Th2 detected by the second coolant temperature sensor 124 is also calculated. That is, in step S3, the supercooling degree Pc-Th2 of the refrigerant immediately before the outlet in the indoor heat exchanger 71 is also calculated. And even when this subcooling degree Pc-Th2 continues more than t2 minutes (for example, 2 minutes) and is smaller than T2 degreeC (for example, 5 degreeC), liquid refrigerant is hardly accumulated in the indoor heat exchanger 71. It judges that it is not, and it transfers to step S4. As a result, the indoor expansion valve 72 is in a fully closed state. On the other hand, when neither of the above two conditions for step S3 is established, the opening degree of the indoor expansion valve 72 is maintained at the opening degree in the current state.

By the way, in the above-described step S1 or step S3, when the amount of the refrigerant in the indoor heat exchanger 71 is detected using the subcooling degree of the refrigerant, the amount of the refrigerant may not be accurately determined. Specifically, for example, when the indoor fan 73 is stopped with the start of the pause operation, the ambient temperature of the indoor heat exchanger 71 becomes a relatively high temperature. On the other hand, in such a state, the detection temperature of the first refrigerant temperature sensor 123 or the second refrigerant temperature sensor 124 is also likely to be higher than the actual refrigerant temperature under the influence of the temperature around the indoor heat exchanger 71. Therefore, in step S1 or step S3, despite the fact that a large amount of refrigerant is actually accumulated in the indoor heat exchanger 71, the supercooling degree of the refrigerant becomes a small value and the indoor expansion valve 72 remains closed. There may be a case.

Thus, in this opening degree control operation, when the indoor expansion valve 72 continues to be closed for more than t3 minutes (for example, 20 minutes) in step S5, the amount of refrigerant in the indoor heat exchanger 71 is not accurately detected. It is assumed that there is no possibility to proceed to step S6. In step S6, the opening degree of the indoor expansion valve 72 is opened at a predetermined opening degree (for example, 352 pulses). As a result, when the refrigerant accumulates in the indoor heat exchanger 71, the refrigerant is quickly discharged to the outside of the indoor heat exchanger 71.

When the refrigerant is circulated in the indoor heat exchanger 71 in this manner, the amount of refrigerant in the indoor heat exchanger 71 can be easily detected in the subsequent determination of step S1 and step S3. That is, since the refrigerant continues to be supplied into the indoor heat exchanger 71 after the end of step S6, the refrigerant flowing through the indoor heat exchanger 71 becomes less affected by the ambient temperature. In this way, the supercooling degree of the refrigerant is avoided to be small due to the influence of the ambient temperature. Therefore, in the subsequent determination of step S1 or step S3, the amount of refrigerant in the indoor heat exchanger 71 can be accurately detected to control the opening degree of the indoor expansion valve 72.

As described above, in the opening degree control operation shown in Fig. 5, the steps S1 to S6 are repeated to open the indoor expansion valve 72 according to the amount of refrigerant accumulated in the indoor heat exchanger 71 in the paused state. Is properly adjusted. As a result, since the refrigerant pooling in the indoor heat exchanger 71 is eliminated, the cooling capacity of the refrigerating heat exchanger 81 and the freezing heat exchanger 91 can be avoided beforehand.

<Operation change control after pause operation>

On the other hand, even after performing the above-described opening control operation after the temporary stop operation of the indoor heat exchanger 71, the refrigerant pooling in the indoor heat exchanger 71 may not be eliminated. Specifically, the air conditioning unit 12 is installed at a relatively high position with respect to the outdoor unit 11 of the refrigerating device 10, and the connection pipe between the outdoor unit 11 and the air conditioning unit 12 (the first gas side). When the head difference (pressure difference) of the connecting pipe 32 is large, each compressor may be operated even if the opening degree of the indoor expansion valve 72 becomes the developing direction (for example, 2000 pulses) by the opening degree control operation described above. The discharged refrigerants 41 and 42 are supplied only to the outdoor heat exchanger 44, and there is a possibility that the refrigerant accumulated in the indoor heat exchanger 71 cannot be sufficiently discharged.

Therefore, in the refrigerating device 10 of the present embodiment, after the indoor heat exchanger 71 is temporarily stopped at the time of heating operation, even if the above-described opening degree control operation is performed, the refrigerant pool in the indoor heat exchanger 71 is kept. If not solved, the operation control means 102 of the controller 100 performs the following control operation.

As shown in Fig. 6, first in step S11, a determination is made as to whether or not the refrigerant pool in the indoor heat exchanger 71 has yet been resolved. Specifically, in step S11, when the subcooling degree Pc-Th1 of the refrigerant entering the indoor heat exchanger 71 continues for more than t4 minutes (for example, 20 minutes) and is greater than T1 ° C, the indoor heat exchanger 71 It is determined that the coolant pool in the c) has not yet been resolved, and the flow proceeds to step S12. As a result, this refrigerating device 10 performs the heat recovery operation shown next.

In the heat recovery operation, the first four-way switching valve 47 is set to the second state, and the second four-way switching valve 48 and the third four-way switching valve 49 are set to the first state. In addition, the outdoor expansion valve 46 and the flow regulating valve 63 are fully closed, and the first solenoid valve SV-1 and the second solenoid valve SV-2 are opened. Moreover, the opening degree of the indoor expansion valve 72, the refrigeration expansion valve 82, and the refrigeration expansion valve 92 is adjusted suitably, respectively. In addition, each of the fans 50, 73, 83, 93, the first compressor 41, the second compressor 42, and the booster compressor 94 are in an operating state, respectively.

The refrigerant compressed by the first compressor 41 and the second compressor 42 respectively joins the discharge pipe 57 and then flows through the first crossover valve 47 to the indoor heat exchanger 71. In the indoor heat exchanger (71), the refrigerant accumulated therein is pressurized by the high pressure refrigerant and discharged to the outside of the indoor heat exchanger (71). In addition, in the indoor heat exchanger (71), since the refrigerant radiates and condenses the indoor air, the heating operation is temporarily performed in the indoor heat exchanger (71). The refrigerant flowing out of the indoor heat exchanger (71) is reduced in pressure when passing through the indoor expansion valve (72), and then flows into the first liquid distributor (31a). The refrigerant flowing into the first liquid distributor 31a flows branched into the second liquid distributor 31b and the third liquid distributor 31c.

The refrigerant introduced into the second liquid distributor (31b) is used for cooling in the storage of the refrigerating showcase (13). The refrigerant flowing into the third liquid distributor 31c is used for cooling in the storage of the freezing showcase 14. The refrigerant used for cooling in the cabinets of the showcases 13 and 14 joins in the second gas side connecting pipe 33 and is sucked into the first compressor 41 and the second compressor 42, respectively.

As described above, in the heat recovery operation, unlike the heating operation described above, the discharge refrigerant of the first compressor 41 and the second compressor 42 is supplied only to the air conditioning unit 12 side. Thereby, even if the head difference from the outdoor unit 11 to the air conditioning unit 12 is large, the high pressure refrigerant can be supplied to the air conditioning unit 12 reliably. As a result, the refrigerant accumulated in the indoor heat exchanger (71) is reliably discharged from the air conditioning unit (12) to be used for cooling in the storage of each showcase (13, 14).

On the other hand, during such heat recovery operation, in step S13 of FIG. 6, it is determined whether or not the coolant in the indoor heat exchanger 71 is released. Specifically, in step S13, when the subcooling degree Pc-Th2 of the refrigerant in the indoor heat exchanger 71 continues for more than t5 minutes (for example, 2 minutes) and is less than T2 ° C, the pooling of the refrigerant is resolved. It is determined and the process proceeds to step S14. As a result, the heat recovery operation is terminated in step S14, and the indoor heat exchanger 71 is brought to a pause state again. Further, in step S13, even when the heat recovery operation continues for more than t6 minutes (for example, three minutes), it is regarded that the coolant pool is reliably canceled, and the process proceeds to step S14.

Effect of Embodiments

In the said embodiment, the following effects are exhibited.

In the above embodiment, after the indoor heat exchanger 71 is temporarily stopped at the time of heating operation, the indoor expansion valve 72 is based on the indicator (the supercooling degree of the refrigerant) indicating the amount of refrigerant accumulated in the indoor heat exchanger 71. The opening degree control operation for adjusting the opening degree of the device is performed. Specifically, in this opening degree control operation, when the amount of accumulated refrigerant in the indoor heat exchanger 71 increases, the opening degree of the indoor expansion valve 72 is increased. Thereby, according to the said embodiment, the refrigerant | coolant accumulated in the indoor heat exchanger 71 can be discharged to the outside suitably, and can be sent to the refrigeration showcase 13 or the freezing showcase 14. Therefore, it is possible to reliably solve the refrigerant pool in the indoor heat exchanger 71 in the paused state, thereby avoiding the deterioration in the cooling capacity of the storage cabinets 13 and 14 in the storage.

In addition, in the opening degree control operation, when the amount of refrigerant accumulated in the indoor heat exchanger 71 is small, the opening degree of the indoor expansion valve 72 is reduced. As a result, according to the above embodiment, the refrigerant amount to be sent to the showcases 13 and 14 is not excessively supplied into the indoor heat exchanger 71 even though the refrigerant pool in the indoor heat exchanger 71 has already been eliminated. Can be secured sufficiently. Therefore, the fall of the cooling capacity in the storage of each showcase 13 and 14 can be more effectively avoided.

In addition, in the opening degree control operation of the above embodiment, the amount of refrigerant accumulated in the indoor heat exchanger 71 is detected by using the supercooling degree of the inlet side of the indoor heat exchanger 71 or the internal refrigerant. Thereby, according to the said embodiment, the refrigerant pool in the indoor heat exchanger 71 can be grasped comparatively easily.

In the opening degree control operation of the above embodiment, the indoor expansion valve 72 is continuously closed for a predetermined time or more in consideration of the fact that the supercooling degree of the refrigerant is reduced by the influence of the ambient temperature of the indoor heat exchanger 71. In this case, the indoor expansion valve 72 is opened. Thereby, according to the said embodiment, although the refrigerant | coolant accumulates in the indoor heat exchanger 71, it can be avoided that the indoor expansion valve 72 will remain closed and the inside of the indoor heat exchanger 71 It is possible to reliably solve the refrigerant pool in the tank.

When the coolant is supplied into the indoor heat exchanger 71 in this manner, the subcooling degree of the refrigerant is less likely to be affected by the ambient temperature of the indoor heat exchanger 71 in the subsequent opening degree control operation. The amount of refrigerant in 71 can be accurately detected. Thereby, according to the said embodiment, the opening degree of the indoor expansion valve 72 can be appropriately controlled according to the amount of refrigerant accumulated in the indoor heat exchanger 71. Therefore, the coolant pool in the indoor heat exchanger 71 can be reliably eliminated, and the amount of coolant to be supplied to the showcases 13 and 14 can be sufficiently secured.

Further, in the above embodiment, when the refrigerant pooling in the indoor heat exchanger 71 is not solved even if the opening degree control operation by the opening degree control means 101 is performed after the temporary stop operation of the indoor heat exchanger 71, The heat recovery operation is performed in the refrigerant circuit 20. In this heat recovery operation, the total amount of refrigerant discharged from each of the compressors 41 and 42 is supplied toward the indoor heat exchanger 71. Therefore, according to the above embodiment, even when the connection pipe head difference from the outdoor unit 11 to the air conditioning unit 12 is relatively large, the discharged refrigerant of the compressors 41 and 42 can be reliably supplied to the indoor heat exchanger 71. Therefore, the refrigerant accumulated in the indoor heat exchanger 71 can be reliably eliminated.

(Other Embodiments)

About the said embodiment, you may have the following structures.

In the above embodiment, one air conditioner unit 12 is connected to the outdoor unit 11. However, a plurality of air conditioning units of this kind may be connected to the outdoor unit 11. Also in this case, after stopping each indoor heat exchanger of each air conditioning unit and performing the opening degree control operation mentioned above, the refrigerant pool of each indoor heat exchanger can be eliminated.

In the above embodiment, the indoor expansion valve 72 is completely closed as a temporary stop operation of the indoor heat exchanger 71 during the heating operation. However, the temporary expansion operation may be performed to tighten the indoor expansion valve 72 to a minute opening degree. Also in this case, since the coolant accumulates in the indoor heat exchanger 71, the coolant pool can be eliminated by performing the opening degree control operation described above.

In the above embodiment, the amount of refrigerant accumulated in the indoor heat exchanger 71 in the paused state is determined from the inflow side of the indoor heat exchanger 71 and the supercooling degree of the internal refrigerant. However, the amount of refrigerant accumulated in the indoor heat exchanger 71 may be determined by other methods.

The above embodiments are essentially preferred examples and are not intended to limit the present invention, the application thereof, or the scope of use thereof.

As described above, the present invention is useful with regard to the countermeasure for refrigerant retention of a heat exchanger in a pause state for a refrigeration apparatus having a plurality of use units.

Claims (5)

And a refrigerant circuit comprising a plurality of use side units connected in parallel to a heat source side unit having a compressor and a heat source side heat exchanger, wherein at least one of the plurality of use side units has a heating operation for dissipating heat from the refrigerant. A refrigeration apparatus in which a possible heat exchanger and an expansion valve corresponding to the heated heat exchanger are arranged, On the basis of the first control operation of tightening the opening degree of the expansion valve to the fully closed or the micro-opening degree when the heating heat exchanger is in the pause state, and on the basis of the indicator indicating the amount of refrigerant accumulated in the heating heat exchanger after the end of the first control operation. And an opening degree control means for performing a second control operation for adjusting the opening degree of the expansion valve. The method according to claim 1, The first control operation of the opening degree control means is an operation of closing the expansion valve completely. The method according to claim 1 or 2, In the second control operation of the opening degree control means, the subcooling degree of the refrigerant at the inlet side of the heating heat exchanger or the subcooling degree of the refrigerant in the heating heat exchanger is used as an index indicating the amount of refrigerant accumulated in the heating heat exchanger. Refrigeration unit. The method according to claim 3, In the second control operation of the opening degree control means, the expansion valve is forcibly opened when the expansion valve remains closed for a predetermined time or more. The method according to claim 1, In the use side unit where the heating heat exchanger is arranged and the other use side unit, a cooling heat exchanger capable of a cooling operation in which the refrigerant absorbs heat from the air is arranged, The refrigerant circuit is configured to enable a heat recovery operation in which the discharged refrigerant of the compressor radiates heat in the heating heat exchanger, and then absorbs in the compressor after absorbing heat in the cooling heat exchanger. During the second control operation of the opening degree control means, when the indicator indicating the amount of refrigerant accumulated in the heating heat exchanger continues to exceed the prescribed value for a predetermined time or more, it is provided with operation control means for temporarily performing the heat recovery operation. Refrigerating apparatus characterized in.

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