JP2013002678A - Condensing unit set and refrigeration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the risk that efficiency of defrosting becomes worse when the defrosting is performed in an interior unit.SOLUTION: There is provided a condensing unit set including a plurality of condensing units (3a, 3b, and 3c) equipped with compressors (31L, 31M, and 31R) and low-pressure sensors (PL) which detect pressures of refrigerants sucked into the compressors respectively. The condensing unit set is equipped with an operation control part (41) which controls an operation of a condensing unit (3) so as to perform defrosting in the interior unit (2) by driving and controlling the compressor. The operation control part (41) further controls to operate other condensing units (3) which are not in operation when any one of pressures of the refrigerants detected by the low-pressure sensors (PL) of condensing units (3a, 3b, and 3c) in operation to perform the defrosting in the interior unit (2) decreases below a predetermined pressure (Pb).

Description

  The present invention relates to a condensing unit set including a plurality of condensing units and a refrigeration apparatus including the condensing unit set, and more particularly to a technique for operating a condensing unit so as to perform defrosting in an indoor unit.

  Conventionally, in a refrigeration apparatus having a refrigerant circuit that circulates refrigerant and performs a vapor compression refrigeration cycle, the refrigerant flowing through the internal heat exchanger (indoor heat exchanger) is absorbed by the internal air and evaporated. Thus, the refrigeration cycle operation for cooling the internal air is performed.

  Further, as in Patent Document 1 below, if a predetermined condition is satisfied during the refrigeration cycle operation, it is determined that the indoor unit has frost formation, and the refrigerant is circulated in the direction opposite to that during the refrigeration cycle operation. The four-way switching valve is switched, whereby the high-pressure refrigerant discharged from the compressor of the condensing unit flows into the indoor unit, and the indoor unit is radiated from the high-pressure refrigerant in the internal heat exchanger (indoor heat exchanger). A so-called reverse cycle defrost operation (defrost operation) is performed in which the frost is melted and defrosted (defrost).

JP 2010-164295 A

  However, when the above-described technology is applied and the above defrost operation is performed in a refrigeration apparatus having a large space to be cooled, such as a refrigeration container, the high-pressure refrigerant flowing from the condensing unit is transferred from the indoor heat exchanger. When condensed, the refrigerant becomes liquid refrigerant, and a large amount of refrigerant may accumulate in the indoor heat exchanger having a large internal volume. As a result, the amount of refrigerant circulated from the condensing unit to the indoor unit becomes insufficient, and it becomes difficult for the refrigerant to circulate, and the defrosting efficiency may deteriorate.

  Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to reduce the possibility that the efficiency of defrosting will deteriorate when defrosting is performed in an indoor unit.

  The condensing unit set of the present invention includes a compressor (31L, 31M, 31R) and a low pressure sensor (PL) for detecting the pressure of refrigerant sucked into the compressor (31L, 31M, 31R), respectively. A condensing unit set comprising a plurality of condensing units (3a, 3b, 3c), wherein the compressor (31L, 31M, 31R) is driven and controlled to defrost in the indoor unit (2). An operation control unit (41) for controlling the operation of the condensing unit (3) to be performed, and the operation control unit (41) is a condensing unit in operation so as to perform defrosting in the indoor unit (2) Any of the refrigerant pressures detected by the low pressure sensor (PL) (3a, 3b, 3c) is a predetermined pressure. (Pb) becomes below, further be operated other condensing unit that is not operated (3).

  For example, when the above-described defrost operation is performed in a refrigeration apparatus having a large space to be cooled, such as a refrigeration container, the high-pressure refrigerant circulated from the condensing unit (3) to the indoor unit (2) is an indoor heat exchanger. By condensing, it becomes liquid refrigerant, and a large amount of refrigerant accumulates in the indoor heat exchanger having a large internal volume. As a result, the amount of refrigerant circulated to the compressors (31L, 31M, 31R) of the condensing unit (3) decreases, and thereafter, the compressors (31L, 31M, 31R) of the condensing unit (3) again. The amount of refrigerant that is discharged and circulated to the indoor unit (2) is also reduced.

  In the configuration of the present invention, any one of the refrigerant pressures detected by the operation control unit (41) by the low pressure sensor (PL) of the operating condensing unit (3) so as to perform defrosting in the indoor unit (2). However, it is determined that the amount of refrigerant sucked into the compressors (31L, 31M, 31R) of the condensing unit (3) has decreased by decreasing to a level equal to or lower than a predetermined pressure Pb.

  And if the said judgment is made, since the condensing unit (3) operated so that defrosting may be performed in the indoor unit (2) is further added, the condensing unit (3) operated in addition is also added. The refrigerant discharged from the compressors (31L, 31M, 31R) is also circulated to the indoor unit (2).

  This eliminates the shortage of the amount of refrigerant circulated to the indoor unit (2) when defrosting is performed in the indoor unit (2). For this reason, the possibility that the refrigerant is hardly circulated is reduced, and the possibility that the efficiency of defrosting is reduced is reduced.

  Further, in the condensing unit set, the operation control unit (41) is any one of a plurality of condensing units (3a, 3b, 3c) at the start of defrosting in the indoor unit (2). It is preferable to operate only the condensing unit (3).

  In this configuration, no condensing unit (3) is in operation. At the start of defrosting in the indoor unit (2), any one of the plurality of condensing units (3a, 3b, 3c) The condensing unit (3) is operated so as to defrost in the indoor unit 2 by being limited to the above.

  Therefore, the amount of high-pressure refrigerant flowing into the indoor unit (2) at the start of operation is smaller than when a plurality of condensing units (3) are operated to perform defrosting in the indoor unit 2 at the start of operation. Become.

  For this reason, at the start of operation, a large amount of the high-pressure refrigerant suddenly flows into the indoor unit (2), so that only a part of the frost on the indoor unit (2) is peeled off due to the rapid heat transfer from the large amount of high-pressure refrigerant. The possibility that frost formation in other parts will not be removed is reduced.

  The condensing unit set further includes a high pressure sensor (PH) for detecting the pressure of the refrigerant discharged from the compressor (31L, 31M, 31R), and the operation control unit (41) The refrigerant pressure detected from the high pressure sensor PH provided in the operating condensing unit (3) so as to perform defrosting in the unit (2) is the time from the start of the operation of the condensing unit (3). It is preferable to drive the compressors (31L, 31M, 31R) so as to increase as time elapses.

  In this configuration, the refrigerant pressure detected from the high pressure sensor (PH) provided in the operating condensing unit (3) so as to perform defrosting in the indoor unit (2) is the condensing unit (3). The compressors (31L, 31M, 31R) are driven so as to increase as time elapses from the start of the operation.

  Accordingly, the refrigerant whose pressure is gradually increased as time passes is circulated to the indoor unit (2), that is, the temperature of the circulated refrigerant gradually increases as time elapses. Will gradually increase. As a result, the ability to remove frost in the indoor unit (2) is gradually improved, so that the possibility that only a part of the frost is peeled off and the other parts are not removed is reduced.

  Further, the refrigeration apparatus of the present invention includes the condensing unit set and an evaporator (23), and each condensing unit (3a, 3b,) provided in the evaporator (23) and the condensing unit set is provided. 3c) and an indoor unit (2) that forms a refrigerant circuit (10).

  ADVANTAGE OF THE INVENTION According to this invention, when performing defrost in an indoor unit, it becomes possible to reduce the possibility that the efficiency of defrost will worsen.

The schematic block diagram which shows an example of a structure of the freezing apparatus which concerns on this invention. The flowchart which shows an example of the operation control of the condensing unit by the operation control part at the time of the defrost operation of a freezing apparatus. The flowchart which shows an example of the drive control of the compressor of the condensing unit by the operation control part at the time of the defrost operation | movement of a freezing apparatus.

[First embodiment]
Hereinafter, a refrigeration apparatus according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the refrigeration apparatus 1 includes three condensing units 3 a, 3 b, 3 c, two indoor units 2 a, 2 b, and a control unit 4.

  In the figure, the three condensing units 3a, 3b, and 3c are assumed to have the same configuration, and the description of each part in the condensing units 3b and 3c is omitted. Similarly, it is assumed that the two indoor units 2a and 2b have the same configuration, and description of each part in the indoor unit 2b is omitted. In the following description, the three condensing units 3a, 3b, and 3c are collectively referred to as a condensing unit 3. Similarly, when the two indoor units 2a and 2b are described generically, they are indicated as the indoor unit 2.

  Each condensing unit 3 a, 3 b, 3 c includes a condensing unit circuit 30, and each indoor unit 2 a, 2 b includes an indoor unit circuit 20. Further, the refrigeration apparatus 1 includes a liquid refrigerant pipe 11 and a gas refrigerant pipe 12, and each condensing unit circuit 30 and each indoor unit circuit 20 are connected by the liquid refrigerant pipe 11 and the gas refrigerant pipe 12. A refrigerant circuit 10 including a refrigerant circulation system is configured.

  The condensing unit circuit 30 includes two closing valves 13 and 14 at the end.

  The shut-off valve 13 is connected to one end of the liquid refrigerant pipe 11. One end of the liquid refrigerant pipe 11 is branched into three, and each branched end is connected to a closing valve 13 of each condensing unit 3a, 3b, 3c. The other end of the liquid refrigerant pipe 11 is connected to the liquid side of each indoor unit circuit 20.

  The shut-off valve 14 is connected to one end of the gas refrigerant pipe 12. One end of the gas refrigerant pipe 12 is branched into three, and each branched end is connected to a closing valve 14 of each condensing unit 3a, 3b, 3c. The other end of the gas refrigerant pipe 12 is connected to the gas side of each indoor unit circuit 20.

  The condensing unit circuit 30 includes three compressors 31L, 31M, and 31R, a four-way switching valve 32, a heat exchanger 33, a receiver 34, a supercooling heat exchanger 35, and a supercooling expansion. A valve 36 and an outdoor expansion valve 37 are provided.

  The three compressors 31L, 31M, and 31R are constituted by, for example, a totally hermetic high-pressure dome type scroll compressor, and are connected in parallel to each other. The compressor 31L is configured as a variable capacity compressor having a variable capacity by changing the output frequency of the inverter to change the rotation speed of the electric motor. The compressors 31M and 31R are configured as fixed capacity compressors whose electric motors are always operated at a predetermined rotation speed and whose capacity cannot be changed.

  The compressors 31L, 31M, 31R compress the refrigerant flowing in from the suction pipes 61L, 61M, 61R, and discharge the compressed high-pressure refrigerant to the discharge pipes 62L, 62M, 62R. The discharge pipes 62L, 62M, and 62R include check valves CV that allow only the flow of refrigerant from the compressors 31L, 31M, and 31R toward the discharge merging pipe 62, respectively.

  A discharge junction pipe 62 having one end branched to discharge pipes 62L, 62M, and 62R is connected to the port P1 of the four-way switching valve 32. One end of the port P2 of the four-way switching valve 32 is a suction pipe 61L, A suction junction pipe 61 branched to 61M and 61R is connected. One end (gas side) of the heat exchanger 33 is connected to the port P3 of the four-way switching valve 32, and the closing valve 14 is connected to the port P4 of the four-way switching valve 32.

  In the four-way switching valve 32, the port P1 and the port P3 communicate with each other, the port P2 and the port P4 communicate with each other (the state indicated by the solid line in the figure), the port P1 and the port P4 communicate with each other, And it is comprised so that switching to the state (state shown with the dashed-dotted line in a figure) which the port P2 and the port P3 connect is possible.

  Note that the state where the port of the four-way switching valve 32 communicates is that the condensing unit 3 is operated by the control unit 4 so that the refrigeration apparatus 1 performs the refrigeration cycle operation or the refrigeration apparatus 1 is defrosted as described later. The operation is appropriately switched depending on whether the condensing unit 3 is operated so as to be operated.

  The heat exchanger 33 is configured by, for example, a cross-fin type fin-and-tube heat exchanger, and includes outdoor air sent by a fan 38 provided in the vicinity and refrigerant circulated in the heat exchanger 33. Heat exchange between them. The other end (liquid side) of the heat exchanger 33 is connected to the top of the receiver 34 via the first liquid pipe 65. The first liquid pipe 65 includes a check valve CV that allows only the flow of refrigerant from the other end (liquid side) of the heat exchanger 33 toward the receiver 34.

  The receiver 34 is disposed between the heat exchanger 33 and the supercooling heat exchanger 35 and temporarily stores the high-pressure refrigerant condensed by the heat exchanger 33.

  The supercooling heat exchanger 35 is constituted by, for example, a plate heat exchanger, and exchanges heat between the refrigerants flowing through the high-pressure side flow path 35H and the low-pressure side flow path 35L. The inflow end of the high-pressure side flow path 35 </ b> H is connected to the bottom of the receiver 34, and the outflow end of the high-pressure side flow path 35 </ b> H is connected to the closing valve 13 via the second liquid pipe 66. The second liquid pipe 66 includes a check valve CV that allows only the refrigerant flow from the outflow end of the high-pressure channel 35H toward the closing valve 13.

  On the other hand, the inflow end of the low pressure side flow path 35L is connected to the second liquid pipe 66 via the first branch pipe 67 branched from the upstream side of the check valve CV in the second liquid pipe 66, and the low pressure side flow The outflow end of the passage 35L is connected to one end (inflow end) of the injection pipe 68. The first branch pipe 67 includes a supercooling expansion valve 36. The supercooling expansion valve 36 is constituted by, for example, an electronic expansion valve whose opening degree can be adjusted.

  The other end (outflow end) of the injection pipe 68 branches into three branch injection pipes 68L, 68M, 68R. The three branch injection pipes 68L, 68M, and 68R are connected to the compressors 31L, 31M, and 31R, respectively, and communicate with the compression chamber of the intermediate pressure. That is, these injection pipes 68, 68L, 68M, and 68R constitute an injection circuit that injects gas refrigerant from the supercooling heat exchanger 35 to the compression chambers of intermediate pressure in the compressors 31L, 31M, and 31R.

  The branch injection pipe 68L connected to the variable capacity compressor 31L includes an expansion valve EV, and the branch injection pipes 68M and 68R connected to the fixed capacity compressors 31M and 31R include the check valve CV and the electromagnetic valve. A valve SV is provided.

  Further, one end of the second branch pipe 69 is connected between the check valve CV and the closing valve 13 in the second liquid pipe 66. The other end of the second branch pipe 69 is connected to the upstream side of the check valve CV provided in the first liquid pipe 65. The second branch pipe 69 includes a check valve CV that allows only the flow of the refrigerant toward the first liquid pipe 65.

  Further, a third branch pipe 63 that bypasses the receiver 34 and the supercooling heat exchanger 35 is connected between the first liquid pipe 65 and the second liquid pipe 66. The third branch pipe 63 includes an outdoor expansion valve 37. The outdoor expansion valve 37 is constituted by, for example, an electronic expansion valve whose opening degree can be adjusted.

  The discharge pipes 62L, 62M, and 62R include oil separators 91L, 91M, and 91R, respectively, upstream of the check valve CV. The oil separators 91L, 91M, 91R separate the refrigerating machine oil from the refrigerant discharged from the compressors 31L, 31M, 31R. Oil return pipes 92L, 92M, and 92R are connected to the oil separators 91L, 91M, and 91R, respectively.

  The oil return pipes 92L, 92M, and 92R join to one end (inflow end) of the oil return joining pipe 92. On the other hand, the other end (outflow end) of the oil return merging pipe 92 is connected to the injection pipe 68. That is, the oil return merging pipe 92 communicates with the compression chamber of the intermediate pressure of each compressor 31L, 31M, 31R.

  The oil return pipe 92L includes a capillary tube CP, and the oil return pipes 92M and 92R include a check valve CV and a capillary tube CP in order from the oil separators 91M and 91R. The check valve CV provided in the oil return pipes 92 </ b> M and 92 </ b> R is a valve that allows only the flow of the refrigerating machine oil toward the oil return joining pipe 92.

  Thus, the refrigerating machine oil separated by the oil separators 91L, 91M, 91R is joined to the oil return joining pipe 92 via the oil return pipes 92L, 92M, 92R, respectively, and then each compressor 31L, 31M, It flows into the compression chamber of the intermediate pressure of 31R. That is, since the refrigeration oil from the oil separators 91L, 91M, and 91R is returned to the compression chamber of the intermediate pressure of each of the compressors 31L, 31M, and 31R without passing through the suction pipes 61L, 61M, and 61R, it is cooled with the low-pressure refrigerant. This prevents the viscosity from increasing.

  Further, the condensing unit circuit 30 includes various sensors. Specifically, the discharge pipes 62L, 62M, and 62R are provided with discharge pipe temperature sensors TL, TM, and TR that detect the temperatures of the discharge pipes 62L, 62M, and 62R, respectively. An intake pipe temperature sensor TC for detecting the temperature of the intake pipe is provided.

  In the vicinity of the fan 38, an outside air temperature sensor Tout for detecting the outside air temperature is provided. A first liquid temperature sensor T1 that detects the temperature of the refrigerant flowing into the supercooling heat exchanger 35 is provided on the downstream side of the supercooling expansion valve 36 in the first branch pipe 67, and the injection pipe 68 includes: A second liquid temperature sensor T2 that detects the temperature of the refrigerant flowing out of the subcooling heat exchanger 35 is provided.

  Furthermore, a low pressure sensor PL that detects the pressure of the low-pressure refrigerant sucked into the compressors 31L, 31M, and 31R is provided at the junction of the suction pipes 61L, 61M, and 61R, that is, the outflow end of the suction junction pipe 61. Is provided. On the other hand, a high pressure sensor PH that detects the pressure of the high-pressure refrigerant discharged and joined from the compressors 31L, 31M, and 31R at the joining point of the discharge pipes 62L, 62M, and 62R, that is, the inflow end of the discharge joining pipe 62. Is provided.

  The indoor unit circuit 20 of the indoor unit 2 includes an indoor expansion valve 27, an indoor heat exchanger 23, and a heating pipe 21.

  The indoor expansion valve 27 is configured by, for example, an electronic expansion valve whose opening degree can be adjusted. The indoor heat exchanger 23 is constituted by, for example, a cross fin type fin-and-tube heat exchanger, and is circulated in the indoor heat exchanger 23 and indoor air sent by an indoor fan 28 provided in the vicinity. Exchanges heat with the refrigerant.

  The heating pipe 21 is provided in a drain pan 25 provided below the indoor heat exchanger 23. The drain pan 25 collects the condensed water dripping from the indoor heat exchanger 23, and uses the heat of the refrigerant circulating in the heating pipe 21 to melt the ice blocks formed by freezing of the condensed water. To do.

  Furthermore, the indoor unit circuit 20 includes various sensors. Specifically, an indoor temperature sensor Tin for detecting the indoor temperature is provided in the vicinity of the indoor fan 28, and the pressure of the refrigerant flowing out of the indoor heat exchanger 23 is detected at the outflow end of the indoor heat exchanger 23. An indoor pressure sensor Pin is provided.

  The control unit 4 is constituted by a microcomputer including, for example, a CPU and a memory such as a ROM or a RAM. In the memory, when the operation of the condensing unit 3 is controlled so that defrosting is performed in the indoor unit 2 by the operation control unit 41 described later, the identification information of the condensing unit 3 to be operated is stored. Is memorized. The control unit 4 receives control signals indicating the detected values of the temperature sensors T1, T2, TC, TL, TM, TR, Tout, Tin and the pressure sensors PL, PH, Pin.

  In particular, the control unit 4 functions as an instruction receiving unit 42 and an operation control unit 41.

  The instruction receiving unit 42 receives various instructions related to the operation of the indoor unit 2 and the condensing unit 3 that are input by a user's operation such as an operation button provided on the remote controller or the indoor unit 2 and the condensing unit 3.

  The operation control unit 41 controls driving of the compressors 31L, 31M, 31R, the fan 38, and the indoor fan 28 provided in each indoor unit 2a, 2b or each condensing unit 3a, 3b, 3c, and various valves. The operation of the indoor unit 2 and the condensing unit 3 is controlled by switching 32, 36, 37, 27, EV, SV and adjusting the opening degree.

  In the refrigerant circuit 10, the operation control unit 41 causes the heat exchanger 33 to function as a condenser and the indoor heat exchanger 23 to function as an evaporator to perform a refrigeration cycle operation that performs a vapor compression refrigeration cycle that cools indoor air. The operation of the three condensing units 3a, 3b, 3c is controlled.

  Specifically, the operation control unit 41 is configured so that at least one of the three condensing units 3a, 3b, and 3c is an operation target condensing unit so that the refrigeration apparatus 1 performs the refrigeration cycle operation. Select as 3. Then, at least one of the three compressors 31L, 31M, 31R provided in the selected condensing unit 3 is driven, and the four-way switching valve 32 communicates with the port P1 and the port P3, And it switches to the state (state shown as the continuous line in a figure) in which the port P2 and the port P4 communicate. Further, the operation control unit 41 appropriately adjusts the opening degrees of the subcooling expansion valve 36 and the indoor expansion valve 27, while bringing the outdoor expansion valve 37 into a fully closed state. Furthermore, the operation control unit 41 appropriately opens and closes the expansion valve EV and the electromagnetic valve SV according to a load for cooling the room temperature.

  In this way, the operation control unit 41 drives at least one of the three compressors 31L, 31M, 31R provided in the condensing unit 3 to be operated, so that a solid arrow in the figure. The refrigerant is circulated in the direction.

  The high-pressure refrigerant compressed by the compressors 31L, 31M, 31R flows into the heat exchanger 33 through the discharge pipes 62L, 62M, 62R, the discharge junction pipe 62, and the four-way switching valve 32.

  Oil separators 91L, 91M, 91R provided in the discharge pipes 62L, 62M, 62R separate and store the refrigerating machine oil from the high-pressure refrigerant flowing through the discharge pipes 62L, 62M, 62R. The stored refrigeration oil flows into the injection pipe 68 via the oil return pipes 92L, 92M, 92R and the oil return merging pipe 92.

  The heat exchanger 33 dissipates the condensed high-pressure refrigerant to the outdoor air and condenses it. The condensed refrigerant flows into the second liquid pipe 66 through the first liquid pipe 65, the receiver 34, and the high-pressure side flow path 35H of the supercooling heat exchanger 35. The refrigerant flowing into the second liquid pipe 66 is divided into the first branch pipe 67 and the liquid refrigerant pipe 11.

  The refrigerant flowing into the first branch pipe 67 is depressurized by the supercooling expansion valve 36 and then flows into the low pressure side flow path 35L of the supercooling heat exchanger 35. In the supercooling heat exchanger 35, heat is exchanged between the refrigerant flowing through the high pressure side flow path 35H and the refrigerant flowing through the low pressure side flow path 35L, so that the refrigerant flowing through the high pressure side flow path 35H is supercooled, and the low pressure side flow path 35L. The refrigerant flowing through evaporates. That is, the liquid refrigerant supercooled in the high pressure side flow path 35H flows into the liquid refrigerant pipe 11, and the gas refrigerant evaporated in the low pressure side flow path 35L flows into the injection pipe 68.

  The refrigerant flowing into the liquid refrigerant pipe 11 is diverted to each indoor unit circuit 20. The refrigerant flowing into each indoor unit circuit 20 flows into the heating pipe 21. As a result, the ice block in which the condensed water is frozen in the drain pan 25 is melted by the refrigerant flowing into the heating pipe 21 and the refrigerant flowing into the heating pipe 21 is further subcooled. The refrigerant flowing out from the heating pipe 21 is decompressed by the indoor expansion valve 27 and then flows into the indoor heat exchanger 23.

  The indoor heat exchanger 23 absorbs the low-pressure refrigerant that has flowed in from the indoor air and evaporates it. As a result, the room air is cooled. The evaporated refrigerant is diverted to each condensing unit circuit 30 via the gas refrigerant pipe 12.

  The refrigerant that has flowed into each condensing unit circuit 30 flows into the suction merging pipe 61 via the four-way switching valve 32 and then is divided into the suction pipes 61L, 61M, and 61R. The refrigerant flowing into the suction pipes 61L, 61M, 61R is sucked by the compressors 31L, 31M, 31R, compressed by the compressors 31L, 31M, 31R, and then discharged again.

  On the other hand, the gas refrigerant that has flowed into the injection pipe 68 and the refrigerating machine oil that has flowed into the oil return merging pipe 92, together with the intermediate pressure in the compression mechanisms of the compressors 31L, 31M, 31R via the branch injection pipes 68L, 68M, 68R. Into the compression chamber. The injection amount of the gas refrigerant is adjusted by the opening degree of the supercooling expansion valve 36.

  In the refrigeration cycle operation of the refrigeration apparatus 1, the refrigerant circulation is repeated in this way.

  Further, when the operation control unit 41 determines that the indoor unit 2 has been frosted under a predetermined condition, the operation control unit 41 performs defrosting in the indoor unit 2, so that the operation control unit 41 is in a direction opposite to the refrigeration cycle operation of the refrigeration apparatus 1. The operation of the condensing unit 3 is controlled so as to circulate the refrigerant, that is, the refrigeration apparatus 1 is controlled to perform the reverse cycle defrost operation (defrost operation).

  For example, when the refrigerant pressure detected by any one of the low pressure sensors PL is lower than a predetermined pressure, or the room temperature detected by any one of the room temperature sensors Tin is determined by the operation control unit 41. When the temperature is lower than a predetermined temperature and the refrigerant pressure detected by any one of the indoor pressure sensors Pin is lower than a predetermined pressure, it is determined that the indoor unit 2 is frosted. Thus, the operation of the condensing unit 3 is controlled so that the refrigeration apparatus 1 performs the defrost operation.

  When the refrigeration apparatus 1 is performing a refrigeration cycle operation, the operation control unit 41 instructs a defrost operation instruction input every time a predetermined time elapses or by a user operation such as a remote controller. When received by the receiving unit 42, the operation of the condensing unit 3 may be controlled so that the refrigeration apparatus 1 performs the defrost operation.

  The operation control unit 41 selects at least one of the three condensing units 3a, 3b, and 3c as the operation target condensing unit 3 so that the refrigeration apparatus 1 performs the defrost operation. The identification information of the selected condensing unit 3 is stored in the memory. The operation control unit 41 drives at least one of the three compressors 31L, 31M, 31R provided in the selected condensing unit 3, and sets the four-way switching valve 32 to the port P1. The state is switched to a state where the port P4 communicates and the port P2 communicates with the port P3 (a state indicated by a one-dot chain line in the figure). In addition, the operation control unit 41 appropriately adjusts the opening degrees of the outdoor expansion valve 37 and the indoor expansion valve 27, and fully closes the subcooling expansion valve 36. In addition, the operation control unit 41 opens and closes the expansion valve EV and the electromagnetic valve SV as appropriate according to the operation state.

  Thus, during the defrost operation of the refrigeration apparatus 1, a vapor compression refrigeration cycle is performed in the refrigerant circuit 10 in which the heat exchanger 33 functions as an evaporator and the indoor heat exchanger 23 functions as a condenser. When at least one of the compressors 31L, 31M, 31R is driven, the refrigerant is circulated in the direction of the broken arrow in the figure.

  The high-pressure refrigerant compressed by the compressors 31L, 31M, 31R is sent to the indoor unit circuits 20 via the discharge pipes 62L, 62M, 62R, the discharge junction pipe 62, the four-way switching valve 32, and the gas refrigerant pipe 12. Divided.

  When the high-pressure refrigerant flows into the indoor heat exchanger 23 via the gas refrigerant pipe 12, the frost attached to the indoor heat exchanger 23 is melted by the refrigerant, while the refrigerant is cooled and condensed by the frost. Thereby, defrosting (defrosting) of the indoor heat exchanger 23 is performed. The refrigerant condensed in the indoor heat exchanger 23 is depressurized by the indoor expansion valve 27 and then divided into each condensing unit circuit 30 via the liquid refrigerant pipe 11.

  The low-pressure refrigerant that has flowed into each condensing unit circuit 30 via the liquid refrigerant pipe 11 flows into the heat exchanger 33 via the second branch pipe 69. In addition, the operation control unit 41 adjusts the opening degree of the outdoor expansion valve 37 and merges the refrigerant stored in the receiver 34 to the first liquid pipe 65 via the supercooling heat exchanger 35 and the third branch pipe 63. Thus, the refrigerant to be circulated during the defrost operation is replenished from the receiver 34.

  In the heat exchanger 33, the refrigerant evaporates by exchanging heat with outdoor air. The evaporated refrigerant is sucked into the compressors 31L, 31M, 31R through the four-way switching valve 32, the suction merging pipe 61, and the suction pipes 61L, 61M, 61R. The refrigerant sucked into the compressors 31L, 31M, 31R is discharged again after being compressed, and this circulation is repeated.

  When one of the refrigerant pressures detected by the low pressure sensor PL provided in the condensing unit 3 that is operating so as to perform defrosting in the indoor unit 2 falls below a predetermined pressure, the operation control unit 41 The other condensing unit 3 that is not operated is further operated.

  Below, the flow of the operation control by the operation control part 41 at the time of the defrost operation of the cooling device 1 is demonstrated using FIG. In the following, the operation of the condensing unit 3 so as to perform defrosting in the indoor unit 2 will be described as the defrosting operation of the condensing unit 3.

  As shown in FIG. 2, when the refrigeration cycle operation is performed, the operation control unit 41 determines that the indoor unit 2 has been frosted under a predetermined condition as described above (step S <b> 1; YES), it is determined whether or not all the condensing units 3 provided in the refrigeration apparatus 1 are defrosted (step S2).

  For example, in step S <b> 2, the operation control unit 41 determines whether the identification information of all the condensing units 3 provided in the refrigeration apparatus 1 is stored in the memory of the control unit 4, and is provided in the refrigeration apparatus 1. When the identification information of all the condensing units 3 is stored in the memory of the control unit 4, it is determined that all the condensing units 3 provided in the refrigeration apparatus 1 are defrosted (step S2; YES). In the memory of the control unit 4, identification information of the condensing unit 3 to be defrosted is stored by the operation control unit 41 in step S <b> 4 described later.

  On the other hand, if the identification information of all the condensing units 3 provided in the refrigeration apparatus 1 is not stored in the memory of the control unit 4, the operation control unit 41 has all the condensing units provided in the refrigeration apparatus 1. 3 is determined not to be defrosted (step S2; NO).

  In this way, when the operation control unit 41 determines that all the condensing units 3 included in the refrigeration apparatus 1 are not defrosted (step S2; NO), the operation control unit 41 is input to the control unit 4. It is determined whether any of the detection values of the low pressure sensor PL provided in the defrosting condensing unit 3 is equal to or lower than a predetermined pressure Pb (step S3). The predetermined pressure Pb is determined in advance based on an experimental value such as a test operation before product shipment, and is stored in the memory of the control unit 4.

  In step S3, the operation control unit 41 receives any of the detected values of the low pressure sensor PL provided in the defrosting condensing unit 3 input to the control unit 4 below a predetermined pressure Pb. (Step S3; YES), one condensing unit 3 that has not been defrosted is selected as the condensing unit 3 to be operated, and the identification information of the selected condensing unit 3 is controlled by the control unit. 4 and defrosting the selected condensing unit 3 (step S4). And the operation control part 41 performs step S2 again.

  According to the configuration of the first embodiment, any one of the refrigerant pressures detected by the operation control unit 41 by the low pressure sensor PL of the condensing unit 3 that is defrosting is less than or equal to a predetermined pressure Pb. It is determined that the amount of refrigerant sucked into the compressors 31L, 31M, 31R of the condensing unit 3 has decreased by decreasing to a certain extent. And if the said judgment is made, since the condensing unit 3 operated by defrost is further added, the refrigerant discharged from the compressors 31L, 31M, 31R of the additionally operated condensing unit 3 is also indoors. The unit 2 is circulated.

  This eliminates the shortage of the amount of refrigerant circulated to the indoor unit 2 when defrosting is performed in the indoor unit 2. For this reason, the possibility that the refrigerant is hardly circulated is reduced, and the possibility that the efficiency of defrosting is reduced is reduced.

  At the start of defrosting in the indoor unit 2 where no condensing unit 3 is in operation, in step S4, one condensing unit 3 is selected as an operation target by the operation control unit 41, and a plurality of condensing units 3 are operated. The condensing unit 3 is defrosted by being limited to only one of the condensing units 3a, 3b, 3c.

  Therefore, the amount of high-pressure refrigerant flowing into the indoor unit 2 at the start of operation is smaller than when a plurality of condensing units 3 are defrosted at the start of operation. For this reason, when high-pressure refrigerant suddenly flows into the indoor unit 2 at the start of operation, only a part of the frost on the indoor unit 2 is peeled off due to rapid heat transfer from the large amount of high-pressure refrigerant. The risk that frost formation will not be removed is reduced.

  In step S4, the number of condensing units 3 to be defrosted by the operation control unit 41 is limited to one. However, for example, when the number of frosted indoor units 2 is large, the defrosting operation may be performed. In preparation for the case where it is necessary to circulate a large amount of refrigerant to the indoor unit 2, a configuration may be adopted in which the number of additional units is plural.

[Second Embodiment]
In the following description of the second embodiment, only portions different from the first embodiment will be described in detail, and description of the same portions as the first embodiment will be omitted.

  In the configuration of the second embodiment, in addition to the configuration of the first embodiment described above, the operation control unit 41 detects the refrigerant pressure detected from the high-pressure sensor PH provided in the defrosting condensing unit 3. However, the compressors 31L, 31M, and 31R are driven so as to increase as time elapses from the start time of the defrost operation.

  The control part 4 is further provided with the time measuring part 43, as shown to the broken-line rectangular part of FIG. The timer unit 43 includes a clock transmitter that generates a clock signal at a constant period, and calculates the current time based on the count result of the clock signal generated from the clock transmitter.

  In addition, based on experimental values from test operation before product shipment, the high pressure sensor PH is associated with the elapsed time from the start of the defrost operation so that the value increases as the elapsed time increases. A target value of the detected refrigerant pressure is determined in advance, and the target value is stored in advance in the memory of the control unit 4 in association with the elapsed time.

  Below, the flow of control which drives the compressor 31L, 31M, 31R with which the operation control part 41 in 2nd embodiment was equipped with the condensing unit 3 of defrost operation object is demonstrated using FIG.

  When the operation control unit 41 stores the identification information of the condensing unit 3 to be defrosted in step S4 in the memory, the current time calculated by the time measuring unit 43, that is, the time when the defrosting operation of the condensing unit 3 is started. (Defrost operation start time) is stored in the memory in association with the identification information of the condensing unit 3 (step S10).

  The operation control unit 41 subtracts the defrost operation start time associated with the identification information of each condensing unit 3 from the current time calculated by the time measuring unit 43 for each condensing unit 3 during the defrost operation. The defrost operation time of each condensing unit 3 indicated by the result is calculated (step S11).

  Next, the operation control unit 41 detects, for each condensing unit 3 during the defrost operation, from the high pressure sensor PH that is associated with the defrost operation time of each condensing unit 3 calculated in step S11. The target value of the refrigerant pressure to be used is read from the memory (step S12).

  Then, the operation control unit 41 detects the pressure of the refrigerant detected from the high pressure sensor PH provided in each condensing unit 3 for each condensing unit 3 during the defrost operation in step S12. The output frequency of the inverter that controls the electric motor that drives the compressor 31L provided in each condensing unit 3 is adjusted so as to be a value, and the driving or stopping of the compressors 31M and 31R is switched (step S13). ).

  According to the configuration of the second embodiment, the refrigerant pressure detected from the high pressure sensor PH provided in the defrosting condensing unit 3 starts from the time when the condensing unit 3 starts to defrost. The compressors 31L, 31M, and 31R are driven so as to increase as time passes.

  Accordingly, the refrigerant that has been gradually increased in pressure as time passes is circulated to the indoor unit 2, that is, the amount of heat transferred from the refrigerant gradually increases as time elapses, so that the condensation capacity gradually increases in the indoor unit 2. Become. As a result, the ability to remove frost in the indoor unit 2 is gradually improved, so that the possibility that only a part of the frost is peeled off and the other parts are not removed is reduced.

  As mentioned above, although embodiment of the freezing apparatus which concerns on this invention was described, the freezing apparatus which concerns on this invention is not limited to said embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the meaning. It is. Moreover, the structure and process shown in the said FIG. 1 thru | or FIG. 3 are only the illustration of embodiment which concerns on this invention, and are not the meaning which limits this invention to the said embodiment.

  For example, in the above embodiment, the condensing unit 3 is configured to include the three compressors 31L, 31M, and 31R. However, the present invention is not limited thereto, and one or more compressors are included in the condensing unit 3. It only has to be done. The compressor may be configured by either a variable capacity compressor whose capacity is variable or a fixed capacity compressor whose capacity cannot be changed. Further, the condensing unit 3 may have a simplified configuration that does not include the injection pipes 68, 68L, 68M, and 68R and the supercooling heat exchanger 35, that is, does not include the injection circuit.

1 Refrigeration apparatus 10 Refrigerant circuit 11 Liquid refrigerant pipe 12 Gas refrigerant pipe 2 (2a, 2b) Indoor unit 20 Indoor unit circuit 23 Indoor heat exchanger (evaporator)
3 (3a, 3b, 3c) Condensing unit 30 Condensing unit circuits 31L, 31M, 31R Compressor 32 Four-way switching valve 33 Heat exchanger 34 Receiver 35 Supercooling heat exchanger 4 Control unit 41 Operation control unit 42 Instruction reception Part Pb Predetermined pressure PH High pressure sensor PL Low pressure sensor

Claims (4)

A plurality of condensing units (3a) each comprising a compressor (31L, 31M, 31R) and a low pressure sensor (PL) for detecting the pressure of refrigerant sucked into the compressor (31L, 31M, 31R). , 3b, 3c), a condensing unit set,
An operation control unit (41) for controlling the operation of the condensing unit (3) so as to perform defrosting in the indoor unit (2) by driving and controlling the compressors (31L, 31M, 31R);
The operation control unit (41) is configured to detect any one of the refrigerant pressures detected by the low pressure sensor (PL) of the operating condensing units (3a, 3b, 3c) so as to perform defrosting in the indoor unit (2). When the pressure falls below a predetermined pressure (Pb), a condensing unit set for further operating another non-operating condensing unit (3).   When the operation control unit (41) starts defrosting in the indoor unit (2), only one of the plurality of condensing units (3a, 3b, 3c) is included in the condensing unit (3). The condensing unit set according to claim 1, wherein the condensing unit set is operated. A high pressure sensor (PH) for detecting the pressure of the refrigerant discharged from the compressor (31L, 31M, 31R);
The operation control unit (41) is configured such that the pressure of the refrigerant detected from the high pressure sensor PH provided in the operating condensing unit (3) so as to perform defrosting in the indoor unit (2) The condensing unit set according to claim 1 or 2, wherein the compressor (31L, 31M, 31R) is driven so as to increase as time elapses from the start of operation of the unit (3). The condensing unit set according to any one of claims 1 to 3,
A room having an evaporator (23), wherein the evaporator (23) and each condensing unit (3a, 3b, 3c) provided in the condensing unit set are connected to form a refrigerant circuit (10). Unit (2);
A refrigeration apparatus comprising:

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