JP2013036650A - Refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress frost formation of a drain pan upon cooling operation even when an expansion mechanism is provided at a heat source unit in a refrigerator that can switch cooling operation and defrosting operation in a utilization unit by switching of a four-way switching valve.SOLUTION: The utilization unit 2 includes the drain pan 25 that accommodates condensed water generated at a utilization side heat exchanger 23, a heating pipe 21 that is provided in parallel with a refrigerant flow path in the utilization side heat exchanger 23 in a refrigerant circuit 10 and which is provided for applying heat to the drain pan 25, and a reverse flow prevention mechanism CV1 for inhibiting a low pressure refrigerant after passing through the expansion mechanism 37 from flowing through the heating pipe 21 while allowing a high-pressure refrigerant discharged from a compression mechanism 31 to flow through the heating pipe 21.

Description

  The present invention relates to a refrigeration apparatus capable of switching between a cooling operation and a defrosting operation in a utilization unit by switching a four-way switching valve.

  Conventionally, a refrigeration apparatus including a heat source unit and a utilization unit, and having a refrigerant circuit in which a compression mechanism, a four-way switching valve, a heat source side heat exchanger, an expansion mechanism, and a utilization side heat exchanger are connected by a refrigerant pipe is known. Yes. For example, Patent Document 1 discloses a cooling operation in which cooling is performed in a utilization unit (refrigeration unit) by a refrigerant flow in the normal cycle, and defrosting is performed in the utilization unit by a reverse cycle refrigerant flow in which the four-way switching valve is switched. A refrigeration apparatus that performs a defrosting operation is disclosed.

  In the refrigeration apparatus described in Patent Document 1, an expansion mechanism is provided in the utilization unit, and a heating pipe (drain pan heater) for heating the drain pan, the expansion mechanism, and the utilization side heat exchanger are connected in series in this order. ing. During the cooling operation, the high-temperature and high-pressure refrigerant (hot gas) discharged from the compression mechanism is condensed in the heat source side heat exchanger, then sent to the utilization unit, passed through the heating pipe, and then in the expansion mechanism. And passes through the use side heat exchanger. On the other hand, during the defrosting operation, the high-temperature and high-pressure refrigerant discharged from the compression mechanism is sent to the use unit, passes through the use-side heat exchanger, passes through the expansion mechanism held in a fully opened state, and passes through the heating pipe. To do. Thereby, a use side heat exchanger and a drain pan are defrosted.

JP 2007-127302 A

  By the way, for example, in a relatively small and inexpensive type refrigeration apparatus, an expansion valve may be provided in the heat source unit. In this type of refrigeration apparatus, if a structure in which a heating pipe and a use-side heat exchanger are connected in series as in Patent Document 1 is employed, the low-temperature and low-pressure refrigerant that has passed through the expansion mechanism is used in the heat source unit during the cooling operation. The drain pan is cooled by flowing through the heating pipe. As a result, the drain pan is easily frosted during the cooling operation.

  Therefore, the present invention has been made in view of such a point, and an object of the present invention is to provide a refrigeration apparatus capable of switching between a cooling operation and a defrosting operation in a utilization unit by switching a four-way switching valve. Even when the mechanism is provided in the heat source unit, it is to suppress the frosting of the drain pan during the cooling operation.

  The refrigeration apparatus of the present invention includes a heat source unit (3) and a utilization unit (2). The refrigeration apparatus includes a refrigerant in which a compression mechanism (31), a four-way switching valve (32), a heat source side heat exchanger (33), an expansion mechanism (37), and a use side heat exchanger (23) are connected by a refrigerant pipe. It has a circuit (10). The expansion mechanism (37) is provided in the heat source unit (3). The refrigeration apparatus can switch between a cooling operation and a defrosting operation in the utilization unit (2) by switching the four-way switching valve (32).

  The utilization unit (2) includes a drain pan (25) that stores condensed water generated in the utilization side heat exchanger (23), and a refrigerant flow path in the utilization side heat exchanger (23) in the refrigerant circuit (10). The heating pipe (21) for applying heat to the drain pan (25) and the high-pressure refrigerant discharged from the compression mechanism (31) are allowed to flow through the heating pipe (21). On the other hand, a reverse flow prevention mechanism (CV1) for preventing low-pressure refrigerant after passing through the expansion mechanism (37) from flowing through the heating pipe (21) is provided.

  In this configuration, the heating pipe (21) is provided in parallel with the refrigerant flow path in the use side heat exchanger (23), and the reverse flow prevention mechanism restricts the flow of the heating pipe (21). (CV1) is provided. Therefore, during the defrosting operation, the high-temperature and high-pressure refrigerant discharged from the compression mechanism (31) flows through the heating pipe (21), so that the drain pan (25) is effectively defrosted. On the other hand, during the cooling operation, the low-temperature and low-pressure refrigerant after passing through the expansion mechanism (37) in the heat source unit (3) flows through the heating pipe (21) in the utilization unit (2). ). Thereby, even if it is a case where an expansion mechanism (37) is provided in a heat source unit (3), frosting of the drain pan (25) at the time of cooling operation can be suppressed.

  In the refrigeration apparatus, it is preferable that the utilization unit (2) further includes a decompression mechanism (81) provided in the heating pipe (21).

  In this configuration, by appropriately selecting the degree of throttling of the decompression mechanism (81), it is possible to adjust the diversion ratio between the refrigerant flowing through the refrigerant flow path of the use side heat exchanger and the gas refrigerant flowing through the heating pipe.

  In the refrigeration apparatus, the backflow prevention mechanism (CV1) is a check valve provided in the heating pipe (21), and the decompression mechanism (81) is a capillary tube.

  In the refrigeration apparatus, the utilization unit (2) includes an openable / closable valve (EV), and the openable / closable valve (EV) includes the backflow prevention mechanism (CV1) and the decompression mechanism (81). It is preferable to constitute.

  In this configuration, since an openable / closable valve (EV) is provided, the flow rate of the gas refrigerant that is diverted to the heating pipe during the defrosting operation can be freely adjusted.

  The refrigeration apparatus further includes a control unit (4) for controlling the cooling operation and the defrosting operation, and the defrosting operation is performed on the use side heat from the start of the defrosting operation until a predetermined condition is satisfied. After the first defrosting operation in which defrosting of the exchanger (23) is intensively performed and after the first defrosting operation, the opening / closing valve (EV) is opened more than in the first defrosting operation. It is preferable to include a second defrosting operation in which the flow rate of the high-pressure refrigerant flowing through the heating pipe (21) is increased to be greater than that in the first defrosting operation.

  In the initial stage when the first defrosting operation is started, the frost attached to the use side heat exchanger (23) is in a state where it has not yet melted or has started to melt. Therefore, in this initial stage, the frost adhering to the use side heat exchanger (23) hardly falls on the drain pan (25) and remains attached to the use side heat exchanger 23. Therefore, in the initial stage, it is more preferable to give the heat to the use side heat exchanger (23) than to heat the drain pan (25). Thereby, the time for which frost formation is removed in the use side heat exchanger (23) can be shortened.

  According to the present invention, in the refrigeration apparatus capable of switching between the cooling operation and the defrosting operation in the utilization unit by switching the four-way switching valve, even if the expansion mechanism is provided in the heat source unit, the drain pan during the cooling operation Frost formation can be suppressed.

It is a refrigerant circuit figure which shows the structure of the freezing apparatus which concerns on 1st Embodiment of this invention, and has shown the flow of the refrigerant | coolant at the time of cooling operation. It is a refrigerant circuit figure which shows the structure of the freezing apparatus which concerns on the said 1st Embodiment, and has shown the flow of the refrigerant | coolant at the time of a defrost operation. It is a flowchart which shows the example of control of the freezing apparatus which concerns on the said 1st Embodiment. It is a part of refrigerant circuit diagram which shows the structure of the freezing apparatus which concerns on 2nd Embodiment of this invention, and has shown the flow of the refrigerant | coolant at the time of a defrost operation. It is a flowchart which shows the example of control of the freezing apparatus which concerns on the said 2nd Embodiment. (A) is a refrigerant circuit diagram which shows the structure of the refrigerating apparatus of a reference example, and has shown the flow of the refrigerant | coolant at the time of cooling operation. (B) is a refrigerant circuit diagram which shows the structure of the refrigerating apparatus of a reference example, and has shown the flow of the refrigerant | coolant at the time of a defrost operation.

<First Embodiment>
Hereinafter, the refrigeration apparatus 1 according to the first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the refrigeration apparatus 1 according to this embodiment includes a heat source unit (outdoor unit) 3, a utilization unit (indoor unit) 2, and a control unit 4 that controls these units. Examples of the use unit 2 include an indoor unit for air conditioning, a refrigerator or a freezer used for cooling products such as a store for refrigerated products or frozen products.

  The heat source unit 3 includes a heat source unit circuit 30, and the usage unit 2 includes a usage unit circuit 20. The refrigeration apparatus 1 includes a liquid side communication pipe 11 and a gas side communication pipe 12. The refrigeration apparatus 1 includes a refrigerant circuit 10 in which a heat source unit circuit 30 and a utilization unit circuit 20 are connected by a liquid side communication pipe 11 and a gas side communication pipe 12.

  The heat source 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 side communication pipe 11. The other end of the liquid side connection pipe 11 is connected to the liquid side end of the usage unit circuit 20. The shut-off valve 14 is connected to one end of the gas side communication pipe 12. The other end of the gas side communication pipe 12 is connected to a gas side end of the usage unit circuit 20.

  The heat source unit 3 includes a compressor 31, a four-way switching valve 32, a heat source side heat exchanger 33 as a heat source side heat exchanger, a receiver 34, a heat source side expansion valve 37 as an expansion mechanism, and an accumulator 91. It has.

  As the compressor 31, for example, a hermetic high-pressure dome type scroll compressor can be used. The compressor 31 is 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 compressor 31 compresses the refrigerant flowing in from the suction pipe 61 and discharges the compressed high-pressure refrigerant to the discharge pipe 62. The discharge pipe 62 includes a check valve CV that allows only the flow of refrigerant toward the four-way switching valve 32.

  A discharge pipe 62 is connected to the port P 1 of the four-way switching valve 32, and a suction pipe 61 is connected to the port P 2 of the four-way switching valve 32. A pipe connected to one end (gas side end) of the heat source side heat exchanger 33 is connected to the port P3 of the four-way switching valve 32, and a port connected to the closing valve 14 is connected to the port P4 of the four-way switching valve 32. One gas pipe 71 is connected.

  In the four-way switching valve 32, the port P1 and the port P3 communicate with each other and the port P2 and the port P4 communicate with each other (the state shown in FIG. 1), and the port P1 and the port P4 communicate with each other. In addition, the second state (the state shown in FIG. 2) in which the port P2 and the port P3 communicate with each other can be switched. The first state and the second state are switched by the control unit 4. In the first state, the refrigeration apparatus 1 performs a cooling operation in the usage unit 2. In the second state, the refrigeration apparatus 1 performs a defrost operation in the usage unit 2.

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

  The receiver 34 temporarily stores the high-pressure refrigerant condensed in the heat source side heat exchanger 33 during the cooling operation. One end of the second liquid pipe 66 is connected to the bottom of the receiver 34. The other end of the second liquid pipe 66 is connected to the closing valve 13. The second liquid pipe 66 includes a check valve CV that allows only a refrigerant flow from the bottom of the receiver 34 toward the closing valve 13. The second liquid pipe 66 is provided with a heat source side expansion valve 37 and a filter. As the heat source side expansion valve 37, for example, an electronic expansion valve whose opening degree can be adjusted can be used.

  The first liquid pipe 65 and the second liquid pipe 66 are connected by a third liquid pipe 69. One end of the third liquid pipe 69 is connected to the second liquid pipe 66 between the check valve CV and the closing valve 13, and the other end of the third liquid pipe 69 is connected to the top of the receiver 34 and the check valve CV. Is connected to the first liquid pipe 65. The third liquid pipe 69 includes a filter 83 and a check valve CV that allows only the flow of refrigerant toward the first liquid pipe 65.

  The first liquid pipe 65 and the second liquid pipe 66 are connected by a branch pipe 63 that bypasses the receiver 34. The branch pipe 63 includes a check valve CV that allows only the flow of refrigerant toward the first liquid pipe 65.

  The heat source unit circuit 30 includes various sensors. Specifically, the discharge pipe 62 is provided with a discharge pipe temperature sensor T1 that detects the temperature of the discharge pipe 62. The suction pipe 61 is provided with a suction pipe temperature sensor T2 that detects the temperature of the suction pipe 61. In the vicinity of the fan 38, an outside air temperature sensor Tout for detecting the outside air temperature is provided.

  The suction pipe 61 is provided with a low-pressure sensor PL that detects the pressure of the low-pressure refrigerant sucked into the compressor 31. The discharge pipe 62 is provided with a high-pressure sensor PH that detects the pressure of the high-pressure refrigerant discharged from the compressor 31.

  The utilization unit circuit 20 of the utilization unit 2 includes a utilization side heat exchanger 23 as a utilization side heat exchanger, a drain pan 25, a heating pipe 21, and a check valve CV1 as a backflow prevention mechanism. .

  As the use side heat exchanger 23, for example, a cross fin type fin-and-tube heat exchanger can be used. The use side heat exchanger 23 performs heat exchange between the indoor air sent by the use side fan 28 provided in the vicinity thereof and the refrigerant flowing in the use side heat exchanger 23.

  One end (end portion on the gas side) of the use side heat exchanger 23 is connected to the gas side communication pipe 12 via the second gas pipe 72. The other end (end portion on the liquid side) of the use side heat exchanger 23 is connected to the liquid side communication pipe 11 via the fourth liquid pipe 73.

  The drain pan 25 is a tray that collects the condensed water dripping from the use side heat exchanger 23. The drain pan 25 is disposed below the use side heat exchanger 23.

  The heating pipe 21 is provided in parallel with the refrigerant flow path of the usage-side heat exchanger 23 in the usage unit circuit 20. One end of the heating pipe 21 is connected to the second gas pipe 72. The other end of the heating pipe 21 is connected to the fourth liquid pipe 73. A heating unit 21 a that is a part of the heating pipe 21 is provided in the drain pan 25. As will be described later, the ice blocks generated by the condensation water freezing in the drain pan 25 are melted by the heat of the refrigerant flowing through the heating pipe 21.

  The heating pipe 21 is provided with a check valve CV1 as a backflow prevention mechanism and a capillary tube 81 as a pressure reducing mechanism. The check valve CV1 and the capillary tube 81 are provided in this order between the heating part 21a of the heating pipe 21 and the fourth liquid pipe 73. The check valve CV1 allows the high-pressure refrigerant discharged from the compressor 31 to flow through the heating pipe 21, while allowing the low-pressure refrigerant after passing through the heat source side expansion valve 37 to flow through the heating pipe 21. Stop.

  The utilization unit circuit 20 includes various sensors. Specifically, an indoor temperature sensor Tin that detects the indoor temperature is provided in the vicinity of the use-side fan 28. The fourth liquid pipe 73 is provided with a temperature sensor T3 that detects the temperature of the liquid refrigerant flowing into the use-side heat exchanger 23. The use side heat exchanger 23 is provided with a temperature sensor T4 that detects the temperature of the use side heat exchanger 23.

  The control unit 4 includes a microcomputer including, for example, a CPU and a memory such as a ROM or a RAM. The control unit 4 receives control signals indicating the detection values of the temperature sensors T1, T2, T3, Tout, Tin and the pressure sensors PL, PH. The control unit 4 performs switching of various valves, opening degree adjustment, and the like based on these control signals, and controls the cooling operation and the dehumidifying operation.

(Trial operation when installing refrigeration equipment)
The refrigeration apparatus 1 shown in FIG. 1 is installed on site, and after a predetermined amount of refrigerant is filled in the refrigerant circuit 10, a test run is executed. In this test operation, the compressor 31 is operated and the refrigerant is circulated in the refrigerant circuit 10. At this time, dust contained in the refrigerant before the test operation is captured by the filters 82 and 84.

  The trial operation is performed with the four-way switching valve 32 set to the first state (the same state as the cooling operation) shown in FIG. Therefore, the refrigerant does not flow through the heating pipe 21 provided with the check valve CV1. Therefore, the check valve CV1 and the capillary tube 81 can be prevented from being clogged with dust contained in the refrigerant before the trial operation.

(Cooling operation)
Next, the cooling operation will be described by taking as an example the case where the usage unit 2 is a refrigerator. FIG. 3 is a flowchart illustrating a control example of the refrigeration apparatus 1 according to the first embodiment. In the cooling operation, the control unit 4 controls the four-way switching valve 32 to set the first state shown in FIG. And the control part 4 operates the compressor 31, adjusts the opening degree of the heat-source side expansion valve 37 suitably, and performs cooling operation (step S1).

  In the cooling operation, the high-pressure gas refrigerant discharged from the compressor 31 to the discharge pipe 62 is sent to the heat source side heat exchanger 33 through the four-way switching valve 32. In the heat source side heat exchanger 33, the gas refrigerant dissipates heat to the outdoor air and condenses. The liquid refrigerant condensed in the heat source side heat exchanger 33 flows through the first liquid pipe 65, passes through the receiver 34, and flows into the second liquid pipe 66.

  The liquid refrigerant flowing through the second liquid pipe 66 is reduced in pressure when passing through the heat source side expansion valve 37 to become a low-temperature liquid refrigerant (for example, −5 ° C.). The liquid refrigerant flows from the third liquid pipe 69 through the liquid side closing valve 13 through the liquid side communication pipe 11 and flows into the utilization unit circuit 20.

  In the usage unit circuit 20, the liquid refrigerant is introduced into the usage-side heat exchanger 23. In the usage-side heat exchanger 23, the refrigerant absorbs heat from the air in the cooling chamber of the usage unit 2 and evaporates at an evaporation temperature of about −5 ° C., for example. In the usage unit 2, the air cooled by the usage-side heat exchanger 23 is supplied to the cooling chamber of the usage unit 2, and the temperature of the cooling chamber is maintained at a set temperature (for example, 5 ° C.).

  The gas refrigerant that has flowed out of the use side heat exchanger 23 flows through the second gas pipe 72 and the gas side communication pipe 12 and is sent to the heat source unit 3. The gas refrigerant sent to the heat source unit 3 flows through the first gas pipe 71, the four-way switching valve 32, and the suction pipe 61 and flows into the accumulator 91. The gas refrigerant separated into gas and liquid in the accumulator 91 is sucked into the compressor 31 through the suction pipe 61.

  During the cooling operation, the low-temperature and low-pressure refrigerant after passing through the expansion valve 37 in the heat source unit 3 is prevented from flowing through the heating pipe 21 in the utilization unit 2 by the reverse flow prevention mechanism CV1. Thereby, even if it is a case where the expansion valve 37 is provided in the heat source unit 3, frost formation of the drain pan 25 at the time of cooling operation can be suppressed.

(Defrosting operation)
Next, the defrosting operation will be described. In the following, as shown in FIGS. 1 and 2, the defrosting operation in the refrigeration apparatus 1 according to the first embodiment in which the check pipe CV <b> 1 is provided as the backflow prevention mechanism and the capillary tube 81 is provided as the pressure reduction mechanism in the heating pipe 21. An example will be described.

  When the control unit 4 determines that the usage unit 2 is frosted based on a predetermined condition during the cooling operation (step S2), the control unit 4 switches the four-way switching valve 32 and executes the defrosting operation in the usage unit 2. (Step S3). Specifically, for example, during the cooling operation, the control unit 4 determines that the accumulated time in a state where the refrigerant temperature (evaporation temperature) in the usage-side heat exchanger 23 detected by the temperature sensor T3 is smaller than a predetermined value TS1. When it becomes longer than a predetermined time, it is determined that frost formation has occurred in the use side heat exchanger 23.

  In the defrosting operation, the control unit 4 controls the four-way switching valve 32 to set the second state shown in FIG. 2, operates the compressor 31, and the refrigerant in the refrigerant circuit 10 is in the opposite direction to that during the cooling operation. Executes a reverse cycle defrost that circulates.

  The high-temperature and high-pressure gas refrigerant discharged from the compressor 31 flows through the four-way switching valve 32, the first gas pipe 71, and the gas side communication pipe 12 and is sent to the utilization unit 2. The gas refrigerant sent to the usage unit 2 is divided into the second gas pipe 72 and the heating pipe 21.

  The gas refrigerant flowing through the second gas pipe 72 flows into the use side heat exchanger 23, flows through the use side heat exchanger 23, and then flows out into the fourth liquid pipe 73. At this time, the gas refrigerant dissipates heat and condenses into the liquid refrigerant in the use side heat exchanger 23. The frost adhering to the use side heat exchanger 23 is heated by the heat of the gas refrigerant radiated in the use side heat exchanger 23, and a part of the frost starts to melt. As melting proceeds, the frost attached to the use side heat exchanger 23 falls and is accommodated in the drain pan 25.

  When the gas refrigerant flowing through the heating pipe 21 passes through the heating section 21a, it dissipates heat and condenses into a liquid refrigerant in the heating section 21a. The liquid refrigerant passes through the check valve CV1 and the capillary tube 81, flows into the fourth liquid pipe 73, merges with the liquid refrigerant flowing out from the use side heat exchanger 23, and is sent to the heat source unit 3. The frost accommodated in the drain pan 25 is heated and melted by the heat of the gas refrigerant radiated in the heating part 21a. The molten drain water is discharged out of the drain pan 25 through a drain port (not shown) provided in the drain pan 25.

  As described above, in the first embodiment, the high-temperature liquid refrigerant flows through the heating pipe 21 to prevent frost from adhering to the drain pan 25, and from the frost dropped from the use-side heat exchanger 23 to the drain pan 25 to ice. Can be prevented, and frost can be reliably melted and discharged as drain water.

  The liquid refrigerant introduced into the heat source unit 3 through the liquid side connecting pipe 11 flows into the top of the receiver 34 through the third liquid pipe 69 and flows out from the bottom of the receiver 34 through the second liquid pipe 66. The liquid refrigerant flowing through the second liquid pipe 66 is reduced in pressure when passing through the heat source side expansion valve 37 to become a low-temperature liquid refrigerant. This liquid refrigerant is introduced into the heat source side heat exchanger 33 through the branch pipe 63. In the heat source side heat exchanger 33, the refrigerant absorbs heat from the outside air and evaporates to become a gas refrigerant. The gas refrigerant flowing out of the heat source side heat exchanger 33 is sucked into the compressor 31 through the suction pipe 61.

  In the first embodiment, since the capillary tube 81 is used, a high-temperature gas refrigerant always flows through the heating pipe 21 to heat the drain pan 25 during the defrosting operation. For example, a capillary tube 81 having a throttle suitable for a desired diversion ratio may be selected as the diversion ratio between the gas refrigerant flowing through the second gas pipe 72 and the gas refrigerant flowing through the heating pipe 21.

  When the control unit 4 determines that the defrosting in the utilization unit 2 is completed under a predetermined condition (step S4), the control unit 4 ends the defrosting operation and executes the cooling operation again. The following conditions can be illustrated as conditions for determining the completion of defrosting.

  For example, when the temperature of the refrigerant (evaporation temperature) in the usage-side heat exchanger 23 detected by the temperature sensor T3 becomes larger than a predetermined value during the defrosting operation, the control unit 4 causes the usage-side heat exchanger 23 to It can be determined that the defrosting has been completed. Further, the control unit 4 determines that the defrosting is completed in the use side heat exchanger 23 when the low pressure (intake pressure) detected by the low pressure sensor PL becomes larger than a predetermined value during the defrosting operation. May be. Moreover, when the elapsed time from the start of the defrosting operation exceeds a predetermined value, the control unit 4 may determine that the defrosting is completed in the use side heat exchanger 23.

Second Embodiment
FIG. 4 is a part of the refrigerant circuit 10 (use unit circuit 20) showing the configuration of the refrigeration apparatus 1 according to the second embodiment of the present invention, and shows the flow of the refrigerant during the defrosting operation. FIG. 5 is a flowchart illustrating a control example of the refrigeration apparatus according to the second embodiment.

  In the refrigeration apparatus 1 according to the second embodiment, instead of the check valve CV <b> 1 and the capillary tube 81, a valve that can be opened and closed is provided in the heating pipe 21. An example of the defrosting operation in the refrigeration apparatus 1 will be described below.

  In the second embodiment, since a valve that can be opened and closed is provided, the flow rate of the gas refrigerant that is diverted to the heating pipe 21 during the defrosting operation can be freely adjusted. Specifically, as shown in FIG. 4, in the second embodiment, an electronic expansion valve EV is used as a valve that can be opened and closed. The opening degree of the electronic expansion valve EV can be adjusted. As the valve that can be opened and closed, an on-off valve such as an electromagnetic valve can be used instead of the electronic expansion valve EV.

  In the second embodiment, similarly to the first embodiment, the control unit 4 determines that the usage unit 2 is frosted based on a predetermined condition during the cooling operation (step S11) (step S12). The defrosting operation is executed in the usage unit 2 (steps S13 to S16).

  In the defrosting operation, the control unit 4 performs a first defrosting operation (steps S13 and S14) and a second defrosting operation (steps S15 and S16). In the first defrosting operation, defrosting of the use-side heat exchanger 23 is performed mainly between the start of the defrosting operation and the predetermined condition. In the second defrosting operation, after the first defrosting operation, the flow rate of the high-pressure refrigerant flowing through the heating pipe 21 is increased by increasing the opening of the electronic expansion valve EV than in the first defrosting operation. Do more than when driving.

  In the initial stage when the first defrosting operation is started, the frost adhering to the use side heat exchanger 23 is not melted yet or has started to melt, so it is used without dropping. It remains attached to the side heat exchanger 23. Therefore, at this initial stage, the drain pan 25 has no frost or a small amount even if it exists. Therefore, in the initial stage, it is preferable to give the heat to the use side heat exchanger 23 rather than heating the drain pan 25. Thereby, the time for which frost formation is removed in the use side heat exchanger 23 can be shortened.

  In the first defrosting operation, the flow rate of the refrigerant flowing through the second gas pipe 72 is made larger than the flow rate of the refrigerant flowing through the heating pipe 21. Specifically, for example, in the first defrosting operation, the opening degree of the electronic expansion valve EV can be fully closed. Further, the electronic expansion valve EV may be adjusted to a small degree of opening so that a small amount of gas refrigerant necessary for preheating the drain pan 25 is diverted to the heating pipe 21. In any case, all or most of the high-temperature and high-pressure gas refrigerant discharged from the compressor 31 and introduced into the utilization unit 2 is introduced into the second gas pipe 72.

  The gas refrigerant introduced into the second gas pipe 72 dissipates heat and condenses in the use side heat exchanger 23 to become a liquid refrigerant. In the first defrosting operation of the second embodiment, since the amount of the gas refrigerant introduced into the second gas pipe 72 is larger than that in the first embodiment, the frost attached to the use side heat exchanger 23 falls on the drain pan 25. The time until it can be shortened.

  When it is determined that the predetermined condition is satisfied in the first defrosting operation (Step S14), the control unit 4 proceeds to the second defrosting operation (Step S15). This predetermined condition can be set in association with, for example, the progress of melting of frost attached to the use side heat exchanger 23. Specifically, when the temperature of the use-side heat exchanger 23 detected by, for example, the temperature sensor T4 becomes higher than a predetermined value during the first defrosting operation, the control unit 4 satisfies the predetermined condition. to decide. Further, for example, when the temperature of the refrigerant in the use side heat exchanger 23 detected by the temperature sensor T3 becomes larger than a predetermined value, the control unit 4 may determine that the predetermined condition is satisfied.

  In the second defrosting operation, the control unit 4 increases the flow rate of the high-pressure refrigerant flowing through the heating pipe 21 by increasing the opening of the electronic expansion valve EV than in the first defrosting operation. Larger than. For example, in the second defrosting operation, the flow rate of the refrigerant flowing through the heating pipe 21 can be made larger than the flow rate of the refrigerant flowing through the second gas pipe 72.

  As described above, in the second defrosting operation, since the flow rate of the gas refrigerant flowing through the heating pipe 21 is larger than that in the first defrosting operation, it is possible to shorten the time until the frost stored in the drain pan 25 is melted. Can do. The molten drain water is discharged out of the drain pan 25 through a drain port (not shown) provided in the drain pan 25.

  In the second embodiment, when the control unit 4 determines that the defrosting is completed based on a predetermined condition (step S16), the control unit 4 ends the defrosting operation and executes the cooling operation again (step S11). Examples of conditions for determining the completion of the second defrosting operation include the following conditions.

  For example, when the temperature of the refrigerant (evaporation temperature) in the use-side heat exchanger 23 detected by the temperature sensor T3 becomes larger than a predetermined value during the second defrosting operation, the control unit 4 It can be determined that the melting is complete. In addition, when the low pressure (intake pressure) detected by the low pressure sensor PL becomes greater than a predetermined value during the second defrosting operation, the control unit 4 determines that the frost melting has been completed in the drain pan 25. May be. Moreover, the control part 4 may judge that the melting | fusing of frost was completed in the drain pan 25, if the elapsed time from the 2nd defrost operation start exceeds the predetermined value.

<Reference example>
6A and 6B are refrigerant circuit diagrams illustrating the configuration of the refrigerating apparatus 101 of the reference example. FIG. 6A shows the refrigerant flow during the cooling operation, and FIG. 6B shows the refrigerant flow during the defrosting operation. 6A and 6B, only the utilization unit 102 of the refrigeration apparatus 101 is illustrated. In addition, about the structure similar to the refrigeration apparatus 1 shown in FIG.1 and FIG.2, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  The usage unit 102 includes a heating pipe 121. The heating pipe 121 is provided in parallel with the fourth liquid pipe 73 in the usage unit circuit 120. One end and the other end of the heating pipe 121 are connected to the fourth liquid pipe 73. A heating unit 121 a that is a part of the heating pipe 121 is provided in the drain pan 25. The heating pipe 121 is provided with a check valve CV12. The check valve CV12 allows only a refrigerant flow from the other end 121c of the heating pipe 121 toward the one end 121b.

  The fourth liquid pipe 73 is provided with a check valve CV11 and a filter 104. The check valve CV11 allows only the refrigerant flow from the liquid side communication pipe 11 to the use side heat exchanger 23. The check valve CV11 and the filter 104 are positioned in the fourth liquid pipe 73 between a portion where the one end 121b of the heating pipe 121 is connected and a portion where the other end 121c is connected.

  The filter 104 is provided to prevent the check valve CV11 from being clogged with dust in the refrigerant flowing in the usage unit circuit 120 in the direction shown in FIG. On the other hand, in the refrigeration apparatus 1 according to the first embodiment and the second embodiment, the heating pipe 21 is provided in parallel with the refrigerant flow path of the usage-side heat exchanger 23 in the usage unit circuit 20, and for heating. The pipe 21 is provided with a check valve CV1 that prevents the refrigerant from flowing from the fourth liquid pipe 73 into the heating pipe 21. Therefore, in the refrigeration apparatus 1, the filter 104 as in the reference example can be omitted.

  In the refrigeration apparatus 101 of this reference example, during the defrosting operation shown in FIG. 6B, the refrigerant flows through the heating pipe 121 but does not flow through the filter 104. Therefore, the frost formed on the filter 104 remains as it is. In order to prevent the remaining frost from coming into contact with the fan in this way, it is necessary to provide a heat insulating material on the filter or the like. In addition, if the refrigeration oil in the refrigerant adheres to the filter 104 and moisture contained in the refrigeration oil precipitates in the filter 104, the filter 104 may be clogged.

  This embodiment is summarized as follows.

  In the present embodiment, the heating pipe 21 is provided in parallel with the refrigerant flow path in the use-side heat exchanger 23, and a backflow prevention mechanism CV1 that regulates the flow of the heating pipe 21 is provided. Yes. Therefore, during the defrosting operation, the drain pan 25 is effectively defrosted as the high-temperature and high-pressure refrigerant discharged from the compression mechanism 31 flows through the heating pipe 21. On the other hand, during the cooling operation, the low-temperature and low-pressure refrigerant after passing through the expansion mechanism 37 in the heat source unit 3 is prevented from flowing through the heating pipe 21 in the utilization unit 2 by the reverse flow prevention mechanism CV1. Thereby, even if it is a case where the expansion mechanism 37 is provided in the heat source unit 3, the frost formation of the drain pan 25 at the time of cooling operation can be suppressed.

  Moreover, in this embodiment, since the utilization unit 2 is further provided with the pressure reduction mechanism 81 provided in the heating pipe 21, by appropriately selecting the degree of throttling of the pressure reduction mechanism 81, the utilization side heat exchanger The diversion ratio between the refrigerant flowing through the refrigerant flow path and the gas refrigerant flowing through the heating pipe can be adjusted.

  In the second embodiment, the use unit 2 includes a valve SV whose opening degree can be adjusted, and the valve SV whose opening degree can be adjusted constitutes a backflow prevention mechanism CV1 and a pressure reduction mechanism 81. Therefore, it is possible to freely adjust the flow rate of the gas refrigerant that is diverted to the heating pipe during the defrosting operation.

  Further, in the second embodiment, the defrosting operation is a first defrosting operation in which the defrosting of the use side heat exchanger 23 is executed mainly between the start of the defrosting operation and the predetermined condition, After the first defrosting operation, the flow rate of the high-pressure refrigerant flowing through the heating pipe 21 by increasing the opening degree of the valve SV whose opening degree can be adjusted is larger than that during the first defrosting operation. And a second defrosting operation to increase the amount. Thereby, the time for which frost formation is removed in the use side heat exchanger 23 can be shortened.

<Other embodiments>
As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the meaning.

  For example, in the first embodiment, the case where the use unit 2 includes the decompression mechanism 81 provided in the heating pipe 21 is illustrated, but the decompression mechanism 81 may be omitted.

  In the first embodiment, the backflow prevention mechanism CV1 is a check valve and the decompression mechanism 81 is a capillary tube. However, the present invention is not limited to this.

DESCRIPTION OF SYMBOLS 1 Refrigeration equipment 2 Use unit 3 Heat source unit 4 Control part 10 Refrigerant circuit 20 Use unit circuit 21 Heating piping 21a Heating part 23 Use side heat exchanger 25 Drain pan 30 Heat source unit circuit 31 Compressor 32 Four-way switching valve 33 Heat source side heat Exchanger 37 Heat source side expansion valve (expansion mechanism)
81 Capillary tube CV1 Check valve EV Electronic expansion valve

Claims (5)

A refrigeration apparatus comprising a heat source unit (3) and a utilization unit (2),
A refrigerant circuit (10) in which a compression mechanism (31), a four-way switching valve (32), a heat source side heat exchanger (33), an expansion mechanism (37) and a use side heat exchanger (23) are connected by a refrigerant pipe. The expansion mechanism (37) is provided in the heat source unit (3), and switching between the cooling operation and the defrosting operation in the utilization unit (2) can be performed by switching the four-way switching valve (32). And
The usage unit (2)
A drain pan (25) for containing condensed water generated in the use side heat exchanger (23);
A heating pipe (21) provided in parallel with the refrigerant flow path in the use side heat exchanger (23) in the refrigerant circuit (10), for applying heat to the drain pan (25);
The high-pressure refrigerant discharged from the compression mechanism (31) is allowed to flow through the heating pipe (21), while the low-pressure refrigerant after passing through the expansion mechanism (37) passes through the heating pipe (21). And a reverse flow prevention mechanism (CV1) for preventing the flow.   The said utilization unit (2) is a refrigeration apparatus of Claim 1 further equipped with the pressure reduction mechanism (81) provided in the said piping for heating (21).   The refrigeration apparatus according to claim 2, wherein the backflow prevention mechanism (CV1) is a check valve provided in the heating pipe (21), and the pressure reduction mechanism (81) is a capillary tube. The utilization unit (2) includes an openable / closable valve (EV),
The refrigerating apparatus according to claim 2, wherein the openable / closable valve (EV) constitutes the backflow prevention mechanism (CV1) and the pressure reducing mechanism (81). A control unit (4) for controlling the cooling operation and the defrosting operation;
The defrosting operation is
A first defrosting operation in which defrosting of the use-side heat exchanger (23) is executed mainly between the start of the defrosting operation and a predetermined condition;
After the first defrosting operation, the flow rate of the high-pressure refrigerant flowing through the heating pipe (21) is increased by increasing the opening degree of the openable valve (EV) than in the first defrosting operation. The refrigeration apparatus according to claim 4, including a second defrosting operation that is performed more than in the first defrosting operation.

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