JP4978659B2 - Air conditioner outdoor unit - Google Patents

Description

  The present invention relates to a technique for defrosting a heat exchanger provided in an outdoor unit of an air conditioner.

  When the heat exchanger of the outdoor unit of the air conditioner is frosted during the heating operation of the air conditioner, the heat conductivity of the frosted portion is lowered and the heat exchange efficiency of the heat exchanger is lowered. Is required. When the time required for the defrost operation becomes longer, the proportion of the time during which the heating operation is actually performed in the operation time of the air conditioner decreases, and the efficiency of air conditioning decreases. Therefore, it is preferable that the defrost operation is completed in a short time.

  The following techniques are known as techniques for shortening the defrost operation time. For example, a heat pump hot water supply device disclosed in Patent Document 1 includes a fin-and-tube heat exchanger, and the tubes of the heat exchanger are arranged in a staggered manner along the air flow direction, and the windward side The tube disposed at the lowermost end of the fin is disposed at a position closer to the lower end side of the fin than the tube disposed at the lowermost end on the leeward side. And at the time of a defrost operation, the hot gas discharged from a compressor is made to flow in the tube arrange | positioned at the lowest end of the windward which is most likely to form frost, and the defrost operation time is shortened.

  Further, for example, the air conditioner disclosed in Patent Document 2 includes a bypass circuit that causes hot gas discharged from the compressor to flow through the outdoor heat exchanger by bypassing the indoor heat exchanger, and the outdoor heat exchanger is The refrigerant circuit is divided into two in the vertical direction, and the upper heat exchanger is a larger heat exchanger than the lower heat exchanger. During defrost operation, after defrosting / heating operation for heating with the lower heat exchanger while defrosting the upper heat exchanger, heating with the upper heat exchanger while defrosting the lower heat exchanger By performing the defrosting / heating operation, the defrost time is shortened while continuing the heating operation.

JP 2006-23005 A JP 2008-64381 A

  By the way, when the length of the tube constituting the heat exchanger is increased, a refrigerant pressure loss is generated inside the tube, and the efficiency of the refrigeration cycle is lowered. In order to prevent this, the heat exchanger may be configured with a plurality of passes. Further, the air volume of the outdoor air that is sucked into the outdoor unit by the fan during air conditioning, passes through the heat exchanger, and is released to the outside of the outdoor unit varies depending on the portion of the heat exchanger. Therefore, in the heat exchanger having a plurality of paths, the amount of air received by each path is different. In order to offset the non-uniformity of the air volume and to uniformize the evaporation temperature of the refrigerant at the outlet of each pass and improve the heat exchange efficiency during air conditioning, for example, at one end of each of the plurality of passes A flow rate adjusting mechanism such as a tube may be provided so that the flow rate of the refrigerant flowing through each path decreases as the air volume decreases.

  However, since the fan is stopped at the time of defrost operation, in an air conditioner equipped with such a heat exchanger with a different flow rate of each path, a path with a smaller refrigerant flow rate, i.e., a path with less air volume received during air conditioning, is defrosted. It takes time. This is because during the defrost operation in which the hot gas discharged from the compressor flows through the heat exchanger, the flow rate of the high-temperature gas refrigerant decreases as the refrigerant flow rate decreases.

  On the contrary, in order to shorten the defrosting operation time, if a flow rate adjusting mechanism is provided so that the refrigerant flow rate increases as the air volume received during air conditioning decreases, the refrigerant flow rate decreases as the heat exchange efficiency decreases during air conditioning. As a result, the efficiency of air conditioning decreases.

  The present invention has been made to solve the above problems, and provides an outdoor unit of an air conditioner that can shorten the defrosting operation time without sacrificing the heat exchange efficiency during the heating operation. Objective.

  An outdoor unit of an air conditioner according to claim 1 of the present invention includes a heat exchanger that has a plurality of paths and functions as an evaporator during heating operation, a fan that blows outdoor air to the heat exchanger, and at least the A casing that houses the heat exchanger and the fan, a decompression mechanism that decompresses the refrigerant condensed in the condenser during the heating operation, and a refrigerant decompressed by the decompression mechanism during the heating operation to each inlet of the plurality of paths A flow dividing mechanism for dividing the flow rate, a flow rate adjusting mechanism for adjusting the flow rate of the refrigerant flowing into each inlet during the heating operation, and a flow rate adjusting mechanism for each defrost operation. A bypass pipe for bypassing the flow rate adjusting mechanism for adjusting the flow rate to a predetermined value or less within the flow rate adjusting mechanism, and opening and closing the bypass pipe provided in the bypass pipe. An opening and closing mechanism, and a control unit for controlling each operation mechanism at the time of defrosting operation, the control unit the closing mechanism in the open state at least part of the period during the defrosting operation.

  An outdoor unit for an air conditioner according to a second aspect of the present invention is the outdoor unit for an air conditioner according to the first aspect, wherein one end of the bypass pipe is connected between the pressure reducing mechanism and the flow dividing mechanism. The other end is connected between the flow rate adjusting mechanism and the inlet.

  An outdoor unit for an air conditioner according to a third aspect of the present invention is the outdoor unit for an air conditioner according to the first aspect, wherein one end of the bypass pipe is connected between the flow dividing mechanism and the flow rate adjusting mechanism. The other end is connected between the flow rate adjusting mechanism and the inlet.

  According to the first to third aspects of the invention, the control unit opens the opening / closing mechanism in at least a part of the period during the defrost operation. Therefore, in the defrost operation, the control unit The flow rate adjusting mechanism is bypassed in a path in which a flow rate adjusting mechanism for adjusting the flow rate to a predetermined value or less is provided at the inlet, that is, in a path having a small refrigerant flow rate during heating operation. Therefore, it is possible to increase the hot gas flow rate during the defrosting operation during the heating operation without reducing the heat exchange efficiency during the defrosting operation, thereby reducing the defrosting operation time. can do.

  An outdoor unit for an air conditioner according to a fourth aspect of the present invention is the outdoor unit for an air conditioner according to any one of the first to third aspects, wherein the fan is provided on an upper portion of the casing, and the heat exchange is performed. The plurality of paths of the container are formed in parallel in the vertical direction of the casing, and the flow rate adjusting mechanism is configured such that the flow rate of the refrigerant is decreased as the path is disposed closer to the lower side in the vertical direction.

  An outdoor unit of an air conditioner according to a fifth aspect of the present invention is the outdoor unit of an air conditioner according to the fourth aspect, wherein the bypass pipe is connected to a path disposed closest to the lower side. It is provided only in the adjustment mechanism.

  According to the invention according to claim 4 or 5, the amount of the outdoor air that is sucked into the outdoor unit by the fan during air conditioning, passes through the heat exchanger, and is released to the outside of the outdoor unit decreases in the vertical direction. In the so-called top-blowing type outdoor unit, it is possible to achieve both efficient heating operation and shortening of the defrosting operation time.

  An outdoor unit of an air conditioner according to claim 6 of the present invention is an outdoor unit of an air conditioner that performs a reverse cycle defrost operation according to any one of claims 1 to 5, wherein The interpass pipe for bypassing the refrigerant flowing through the flow rate adjusting mechanism connected to one of the plurality of paths to another path different from the path, and the interpass pipe provided in the interpass pipe. A flow restriction mechanism that restricts the flow rate of refrigerant flowing through the pipe, and the inter-pass piping has at least the refrigerant flow through the flow adjustment mechanism that reduces the refrigerant flow secondly among the flow adjustment mechanisms. The flow rate adjusting mechanism to be reduced is disposed at a position to be bypassed to the connected path.

  According to the sixth aspect of the present invention, the inter-pass piping is bypassed at a position where the refrigerant flowing through the flow rate adjusting mechanism that reduces the refrigerant flow rate secondly is bypassed to the path to which the flow rate adjusting mechanism that reduces the refrigerant flow rate is connected. Since it is disposed at least, the hot gas flow rate can be increased during the defrost operation in the pass having the smallest refrigerant flow rate during the heating operation and the second pass having the smallest flow rate. Therefore, the defrost efficiency of the path that is least likely to be defrosted and then the path that is less likely to be defrosted can be improved, so that the efficiency of the defrost operation can be further improved.

  An outdoor unit of an air conditioner according to a seventh aspect of the present invention is the outdoor unit of the air conditioner according to any one of the first to sixth aspects, wherein the flow rate is provided at an inlet of the path that does not include the bypass pipe. Among the adjustment mechanisms, provided at the inlet of the path to which the flow rate adjustment mechanism that reduces the refrigerant flow rate most during the heating operation is connected, and includes an inlet temperature detection unit that detects the temperature of the inlet, and a timing unit, The control unit continuously decreases the inlet temperature detected by the inlet temperature detection unit over a frosting determination time which is a predetermined time, and the inlet temperature is predetermined. When it becomes less than the frosting determination temperature, which is a temperature, the defrosting operation is started with the opening / closing mechanism in the open state, and when the duration time of the defrosting operation exceeds the end determination time which is a predetermined time, The opening / closing mechanism It terminates the defrosting operation as the closed state.

  According to the invention which concerns on Claim 7, among the flow control mechanisms provided in the inlet of the said path | pass which is not equipped with the said bypass piping, the path | route to which the flow control mechanism which makes the refrigerant | coolant flow volume the smallest at the time of heating operation is connected, ie, the said The defrosting operation is terminated by defrosting the path that is least likely to be defrosted among the paths that are not easily defrosted because no bypass pipe is provided. Therefore, the defrosting of the heat exchanger can be reliably performed.

  An outdoor unit for an air conditioner according to an eighth aspect of the present invention is the outdoor unit for an air conditioner according to any one of the first to sixth aspects, wherein the refrigerant flow rate is the highest in the flow rate adjusting mechanism during heating operation. Provided at the inlet of the path to which a flow rate adjusting mechanism to be reduced is connected, and provided at the inlet of the path without the bypass pipe, and a first temperature detecting unit for detecting a first inlet temperature that is the temperature of the inlet. Among the flow rate adjustment mechanisms that are provided, a second temperature detection unit that is provided at the inlet of the path to which the flow rate adjustment mechanism that reduces the refrigerant flow rate at the time of heating operation is connected and detects the second inlet temperature that is the temperature of the inlet And a pressure detection unit that detects the discharge pressure of the refrigerant discharged from the compressor, and a time measuring unit, wherein the control unit exceeds a frosting determination time that is a predetermined time. Continuously declined and before When the first inlet temperature is lower than a frost determination temperature which is a predetermined temperature and the discharge pressure is lower than a frost determination pressure value which is a predetermined pressure value, the opening / closing mechanism is When the defrost operation is started as an open state and the defrost operation continues during the defrost operation exceeds an end determination time, which is a predetermined time, or the first inlet temperature is a predetermined first When the first end determination temperature is exceeded and the second inlet temperature exceeds the second end determination temperature which is a predetermined second temperature, or the discharge pressure is predetermined. When the end determination pressure value, which is a detected pressure value, is exceeded, and at least one of them is met, the opening / closing mechanism is closed and the defrosting operation is ended.

  According to the invention which concerns on Claim 8, among the flow control mechanisms provided in the inlet of the said path | pass which is not provided with the said bypass piping, the path | route to which the flow control mechanism which makes the refrigerant | coolant flow volume the smallest at the time of heating operation is connected, ie, the said The defrosting operation is terminated by defrosting the path that is least likely to be defrosted among the paths that are not easily defrosted because no bypass pipe is provided. Therefore, the defrosting of the heat exchanger can be reliably performed.

  Further, according to the eighth aspect of the invention, since the start and end of the defrost operation are determined based on the above three conditions, the start and end timings of the defrost operation can be accurately determined. Therefore, since unnecessary defrost operation is not performed, the time for defrost operation can be further shortened.

  An outdoor unit for an air conditioner according to a ninth aspect of the present invention is the outdoor unit for an air conditioner according to any one of the first to sixth aspects, wherein the bypass pipe is included in the flow control mechanism during a defrost operation. Provided at the inlet of the path to which the flow rate adjusting mechanism for reducing the refrigerant flow rate is provided, only at the flow rate adjusting mechanism for reducing the refrigerant flow rate at the minimum. A first temperature detection unit that detects a first inlet temperature, which is a temperature, and a flow rate adjustment mechanism that reduces the refrigerant flow rate secondly in the flow rate adjustment mechanism during heating operation are provided at the inlet of the path. A second temperature detection unit that detects a second inlet temperature that is the temperature of the inlet, a pressure detection unit that detects a discharge pressure of the refrigerant discharged from the compressor, and a timer unit, and the control unit includes: The first inlet temperature The frosting determination time, which is a predetermined time, continuously decreases and the first inlet temperature is lower than a frosting determination temperature, which is a predetermined temperature, and the discharge pressure is set in advance. When the frosting determination pressure value, which is a predetermined pressure value, is less than the frosting determination pressure value, the first defrost operation, which is a defrost operation performed by maintaining the opening / closing mechanism in a closed state, is started, and during the first defrost operation, When the duration of the first defrost operation exceeds a first end determination time which is a predetermined first time, or a second end determination where the second inlet temperature is a predetermined second temperature When the temperature exceeds, or when the discharge pressure exceeds a first end determination pressure value that is a predetermined first pressure value, the first defrost operation is performed when at least one of them is met. Exit and said Following the first defrost operation, a second defrost operation, which is a defrost operation in which the opening / closing mechanism is opened, is started. During the second defrost operation, a second duration of the second defrost operation is determined in advance. When the second end determination time that is a time is exceeded, or when the first inlet temperature exceeds the first end determination temperature that is a predetermined first temperature, or the discharge pressure is determined in advance. When the second end determination pressure value, which is the second pressure value, is exceeded, and at least one of them is met, the open / close mechanism is closed and the second defrost operation is ended.

  According to the ninth aspect of the present invention, since the path other than the path that is most difficult to defrost in the first defrost operation is defrosted and the path that is least likely to be defrosted in the second defrost operation is intensively defrosted, the heat exchanger is more efficiently performed. By defrosting, the defrost time can be shortened.

  Furthermore, according to the invention which concerns on Claim 9, since the start and completion | finish of a 1st defrost driving | operation and a 2nd defrost driving | operation are determined based on said three conditions, respectively, a 1st defrost driving | operation and a 2nd defrost driving | operation are determined. The start and end timing can be accurately determined. Therefore, the time for defrosting can be further shortened.

  According to the outdoor unit for an air conditioner according to the present invention, it is possible to shorten the defrosting operation time without sacrificing the heat exchange efficiency during the heating operation. Accordingly, the proportion of time occupied by the defrost operation during air conditioning is reduced, and the efficiency of air conditioning is improved by increasing the proportion of heating operation time. Therefore, it is possible to reduce power consumption and operation costs.

It is a schematic block diagram of an air conditioner provided with the outdoor unit which concerns on Embodiments 1-4 of this invention. It is a schematic diagram which shows the detail of the piping structure between the pressure reduction mechanism and heat exchanger in the outdoor unit which concerns on Embodiment 1 and 2 of this invention. It is a flowchart which shows the control at the time of the defrost operation and heating operation in the outdoor unit which concerns on Embodiment 1 of this invention. It is a flowchart which shows the control at the time of the defrost driving | operation and heating operation in the outdoor unit which concerns on Embodiment 2 of this invention. It is a flowchart which shows the control at the time of the defrost driving | operation and heating operation in the outdoor unit which concerns on Embodiment 3 of this invention. It is a schematic diagram which shows the detail of the piping structure between the pressure reduction mechanism and heat exchanger in the outdoor unit which concerns on Embodiment 4 of this invention. It is a schematic diagram which shows the detail of the outdoor unit which concerns on deformation | transformation embodiment of this invention. It is a schematic diagram which shows the detail of the outdoor unit which concerns on other modified embodiment of this invention. It is a schematic diagram which shows the outdoor unit which is not provided with bypass piping. (A) is a figure which shows the detail of the piping structure between the flow dividing mechanism and heat exchanger in the said outdoor unit, (B) is a figure which shows the wind speed distribution in the height direction of the said outdoor unit.

  Hereinafter, outdoor units according to Embodiments 1 to 4 of the present invention will be described in detail with reference to the drawings.

<Embodiment 1>
FIG. 1 is a schematic configuration diagram of an air conditioner 1 including an outdoor unit 2 according to Embodiment 1 of the present invention. FIG. 2 is a schematic diagram showing details of the piping configuration between the electronic expansion valve 24 (decompression mechanism) and the outdoor heat exchanger 22 in the outdoor unit 2.

  The air conditioner 1 includes an outdoor unit 2 and an indoor unit 3. The outdoor unit 2 and the indoor unit 3 are connected to each other by an on-site pipe 18 that is a liquid side pipe and an on-site pipe 19 that is a gas side pipe, and constitutes a refrigerant circuit 10. In the present embodiment, the air conditioner 1 performs so-called reverse cycle defrosting that switches the circulation direction of the refrigerant in the refrigerant circuit 10 during the defrost operation.

  The outdoor unit 2 is a so-called top-blow type outdoor unit, and includes an outdoor fan 25 at the top of the casing 20, and outdoor air sucked from a suction port (not shown) provided on the side of the casing 20 is used as outdoor heat. After heat exchange with the refrigerant flowing in the exchanger 22, the refrigerant is blown out from an unillustrated air outlet provided at the top of the casing 20. The outdoor unit 2 includes a compressor 21, an outdoor heat exchanger 22, a flow divider 23 (a flow dividing mechanism), an electronic expansion valve 24 (a pressure reducing mechanism), a four-way switching valve 26, and an outdoor fan 25 connected by a refrigerant pipe 12. And a controller 200 including a control unit 203 that controls these operation mechanisms during the air-conditioning operation and the defrost operation.

  The compressor 21 is, for example, an inverter-controlled scroll compressor that is driven so that its capacity can be adjusted by changing the drive frequency. The compressor 21 compresses the low-pressure gas refrigerant until the pressure becomes equal to or higher than the critical pressure. The discharge side pipe of the compressor 21 is provided with a high pressure sensor 211 (pressure detector). The high pressure sensor 211 detects the pressure of the high pressure gas refrigerant (hot gas) discharged from the compressor 21.

  The outdoor heat exchanger 22 is, for example, a cross fin type fin-and-tube heat exchanger, and functions as a condenser during cooling operation and defrost operation, and functions as an evaporator during heating operation.

  The flow divider 23 is provided in a pipe portion upstream of the outdoor heat exchanger 22 during heating operation. The flow divider 23 distributes the refrigerant in a gas-liquid mixed state, which has been throttled and expanded by the electronic expansion valve 24 during the heating operation, to a plurality of (in this embodiment, five) paths P1 to P5 constituting the outdoor heat exchanger 22. To do.

  The electronic expansion valve 24 is a motor-operated valve whose opening degree can be adjusted provided in a pipe portion on the upstream side of the outdoor heat exchanger 22 during heating operation. The electronic expansion valve 24 expands and decompresses the high-pressure liquid refrigerant condensed in the indoor heat exchanger 32 (to be described later) during the heating operation, flows into the outdoor heat exchanger 22, and operates during the cooling operation and the defrost operation. The flow rate of hot gas to the outdoor heat exchanger 22 is adjusted.

  The outdoor fan 25 blows outdoor air to the outdoor heat exchanger 22 to exchange heat between the refrigerant flowing through the outdoor heat exchanger 22 and the indoor air. In the present embodiment, the outdoor fan 25 is a propeller fan provided at the top of the casing 20 and is driven to rotate by a fan motor 251.

  The four-way switching valve 26 has four ports, the first port of which is connected to the discharge side piping of the compressor 21, the second port of which is connected to the suction side piping of the compressor 21, The third port is connected to the on-site pipe 19 and the fourth port is connected to the outdoor heat exchanger 22. The four-way switching valve 26 is in a state in which the first port and the third port communicate with each other and the second port and the fourth port communicate with each other by the control unit 203 provided in the controller 200 (the solid line in FIG. 1). Between the first port and the fourth port, and the second port and the third port communicate with each other (a state indicated by a broken line in FIG. 1). By the switching operation of the four-way switching valve 26, the circulation direction of the refrigerant in the refrigerant circuit is reversed, and the air conditioner 1 is set to any one of the cooling mode, the heating mode, and the defrost mode. That is, the four-way switching valve 26 is in a state indicated by a solid line in FIG. 1 during the heating operation, and is in a state indicated by a broken line in FIG. 1 during the cooling operation and the defrost operation. Details of the controller 200 will be described later in detail.

  The indoor unit 3 includes an electronic expansion valve 31 and an indoor heat exchanger 32 connected by a refrigerant pipe 13 and an indoor fan 33.

  The electronic expansion valve 31 is a motor-operated valve whose opening degree can be adjusted provided in a refrigerant pipe on the downstream side of the indoor heat exchanger 32 during heating operation. The electronic expansion valve 31 adjusts the flow rate of hot gas to the outdoor heat exchanger 22 during heating operation, and expands and expands the high-pressure liquid refrigerant after condensation in the outdoor heat exchanger 22 during cooling operation and defrost operation. The pressure is reduced and the air flows into the indoor heat exchanger 32.

  The indoor heat exchanger 32 is, for example, a cross fin type fin-and-tube heat exchanger similar to the outdoor heat exchanger 22, and functions as an evaporator during cooling operation and defrost operation, and a condenser during heating operation. Function as.

  The indoor fan 33 sucks indoor air into the indoor unit 3, exchanges heat between the refrigerant flowing through the indoor heat exchanger 32 and the indoor air, and then uses the indoor air after the heat exchange as conditioned air to the outdoors. And discharge. As the indoor fan 33, a turbo fan, a sirocco fan, a cross flow fan, or the like is used according to the shape of the indoor unit 3, and is rotated by a fan motor 331.

  Next, details of the outdoor unit 2, particularly, details of the piping configuration between the electronic expansion valve 24 and the outdoor heat exchanger 22 and details of the controller 200 will be described with reference to FIGS. 2 and 9. Arrows attached to the refrigerant circuit 12 shown in FIGS. 2 and 9 indicate the circulation direction of the refrigerant during the heating operation. The refrigerant circulation direction during the cooling operation and the defrost operation is opposite to the arrow. FIG. 9 is a schematic diagram showing an up-blowing type outdoor unit 2D in which the bypass pipe 220 and the deisathermistor DT2 are removed from the outdoor unit 2. The same components as those of the outdoor unit 2 are denoted by the same reference numerals. FIG. 9A is a schematic diagram showing details of the piping configuration between the flow divider 23 and the outdoor heat exchanger 22 in the outdoor unit 2D, and FIG. 9B is a diagram in the height direction of the outdoor unit 2D. It is a figure which shows wind speed distribution.

  The outdoor heat exchanger 22 included in the outdoor unit 2 includes a plurality of paths, that is, five paths P1 to P5 in this embodiment. In addition to the configuration shown in FIG. 1, the outdoor unit 2 includes capillary tubes CT1 to CT5 (flow rate adjusting mechanisms) positioned between the refrigerant inlets E1 to E5 and the flow dividers 23 of the paths P1 to P5 during heating operation. A bypass pipe 220 for bypassing the capillary tube CT1, a solenoid valve SV (opening / closing mechanism) provided in the bypass pipe 220, a deisathermistor DT1 (first temperature detection unit) provided in the refrigerant inlet E1, and a refrigerant inlet And a de-isather thermistor DT2 (second temperature detector) provided in E2.

  The paths P1 to P5 are formed in parallel in the vertical direction of the casing 20, and the path from the lowermost path P1 to the uppermost path P5 is sequentially stacked. The tube lengths of the paths P1 to P5 are increased in the order of the paths P5 to P1.

  The capillary tubes CT1 to CT5 are selected so that the frictional resistance when the refrigerant passes gradually increases from CT5 to CT1. Therefore, the refrigerant flow rate per unit time decreases sequentially from the path P5 to the path P1.

  One end of the bypass pipe 220 is connected between the electronic expansion valve 24 and the flow divider 23, and the other end is connected between the capillary tube CT1 and the refrigerant inlet E1. When the control unit 203 opens the solenoid valve SV provided in the bypass pipe 220 during the defrost operation, the refrigerant flowing out from the refrigerant inlet E1 (which becomes the refrigerant outlet during the defrost operation) bypasses the capillary tube CT1. It flows through the bypass pipe 220. This is because the refrigerant is easier to pass through the solenoid valve SV having a smaller frictional resistance than the capillary tube CT1 having a large frictional resistance. In the present embodiment, a normally closed solenoid valve is used as the solenoid valve SV, which is closed when not energized and opened when energized.

  The deisathermistor DT1 detects the temperature Tb1 (first inlet temperature) of the refrigerant inlet E1 during the heating operation and the defrosting operation. The deisathermistor DT2 detects the temperature Tb2 (second inlet temperature) of the refrigerant inlet E2 during the heating operation and the defrost operation.

  The controller 200 includes a storage unit 201, a timing unit 202, and a control unit 203. The storage unit 201 includes, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and includes a control program for operating the air conditioner 1, and refrigerant inlets E1 and E2 detected by the de-isather thermistors DT1 and DT2. The temperatures Tb1 and Tb2, the hot gas pressure detected by the high pressure sensor 211, and the like are stored. Furthermore, the storage unit 201 stores a frosting determination time, a frosting determination temperature, a frosting determination pressure value, an end determination time, and the like, which are thresholds when the control unit 203 determines the start and end of the defrost operation. These threshold values will be described in detail later.

  The timer unit 202 includes a clock generator that generates a clock signal at a constant period, and outputs the clock signal to the control unit 203.

  The control unit 203 includes a CPU (Central Processing Unit) and the like, and controls each operation mechanism of the air conditioner 1 during the cooling / heating operation and the defrost operation by executing a control program stored in the storage unit 201 in advance. .

  The outdoor unit 2 is an up-blowing type outdoor unit, and the outdoor heat exchanger 22 is provided to face three of the four inner side surfaces of the casing 20 that has a substantially rectangular parallelepiped shape that is long in the height direction in the installed state. It has been. For this reason, when the outdoor heat exchanger 22 is configured with a single tube, the tube length becomes long, pressure loss of the refrigerant occurs inside the tube, and the efficiency of the refrigeration cycle decreases. By configuring the outdoor heat exchanger 22 with a plurality of passes, that is, five passes P1 to P5 in this embodiment, the tube length of each pass is shortened to reduce the pressure loss.

  Moreover, since the outdoor fan 25 is provided in the upper part of the casing 20, it is suck | inhaled by the outdoor fan 25 inside the outdoor unit 2 at the time of air conditioning, passes the outdoor heat exchanger 22, and is discharge | released outside the outdoor unit 2. The air volume of the outdoor air decreases as the distance from the indoor fan 25 increases (see FIG. 9B). In other words, the portion of the outdoor heat exchanger 22 that is positioned downward in the up-down direction has a lower air volume, so that the heat exchange efficiency is inferior.

  Since the outdoor heat exchanger 22 is configured as described above, the time for the refrigerant flowing into each of the paths P1 to P5 to pass through each of the paths becomes longer in the order of the paths P5 to P1. That is, in the outdoor heat exchanger 22, the lower the heat flow efficiency is, the lower the air volume, so that the lower the heat exchange efficiency, the longer the refrigerant evaporation time, thereby canceling out the uneven air volume. The refrigerant evaporating temperature at the outlet of P5 is made uniform to improve the heat exchange efficiency during air conditioning.

  In the case of an up-blowing type outdoor unit that does not include the bypass pipe 220 as in the outdoor unit 2D shown in FIG. 9A, the lower side path with the smaller refrigerant flow rate is defrosted during the defrost operation in which the outdoor fan 25 stops. It takes time to complete the defrosting of the path P1 located at the bottom. This is because during the defrost operation in which hot gas flows to the outdoor heat exchanger 22, the flow rate of the hot gas decreases as the refrigerant flow rate decreases.

  On the other hand, in the outdoor unit 2, during the defrost operation, the control unit 203 opens the electromagnetic valve SV provided in the bypass pipe 220 and bypasses the refrigerant flowing out from the refrigerant inlet E 1 to the bypass pipe 220. Therefore, during the defrost operation, the refrigerant flow rate in the path P1 is larger than the paths P2 to P5 in which the refrigerant flow rate is limited by the capillary tubes CT2 to CT5. Therefore, since the defrost efficiency of the path P1 is improved, the defrost operation time can be shortened compared to the outdoor unit 2D.

  Moreover, in the outdoor unit 2, the control unit 203 closes the solenoid valve SV during the heating operation, so that the refrigerant does not flow into the bypass pipe 220, and the heat exchange efficiency during the heating operation does not decrease.

  FIG. 3 is a flowchart illustrating the control performed by the control unit 203 during the defrost operation and the heating operation. When the operation of the air conditioner 1 including the outdoor unit 2 is started in the heating operation mode, the normally closed solenoid valve SV is in a closed state (step S101). The controller 203 monitors the temperature Tb1 of the refrigerant inlet E1 detected by the deisathermistor DT1 and the discharge pressure HP of the hot gas discharged from the compressor 21 during the heating operation. It is determined that the heat exchanger 22 has formed frost, and it is determined that it is time to start the defrost operation (YES in step S102). When the condition A1 is not met, the control unit 203 continues the heating operation while continuing the monitoring (NO in step S102).

  Condition A1 is that (1) Tb1 continuously decreases for frost determination time X minutes, (2) Tb1 is less than frost determination temperature th ° C, and (3) discharge pressure HP is less than frost determination pressure value C. This is a case where all three conditions are satisfied. Note that X, th, and C are thresholds determined in advance according to the size of the outdoor heat exchanger 22, the blowing capacity of the outdoor fan 25, and the like, and are stored in the storage unit 201 in advance.

  Subsequent to step S102, the control unit 203 switches the four-way switching valve 26 in the direction indicated by the broken line in FIG. 1 to reverse the refrigerant circulation direction, and turns on the electromagnetic valve SV to open the defrost operation. (Step S103). The control unit 203 monitors the duration of the defrost operation based on the clock signal output from the time measuring unit 202, and discharges the Tb1, the temperature Tb2 of the refrigerant inlet E2 detected by the de-isather thermistor DT2, and the compressor 21. The hot gas discharge pressure HP is monitored, and when the condition B1 is satisfied, it is determined that it is time to end the defrost operation (YES in step S104). When the condition B1 is not met, the control unit 203 continues the defrost operation while continuing the monitoring (NO in step S104).

  Conditions B1 are (1) Tb1 exceeds the first end determination temperature t1, Tb2 exceeds the second end determination temperature t2, and (2) the discharge pressure HP exceeds the end determination pressure value A (Mpa). (3) In the case where any one of the three conditions of the end time elapses after the end determination time T1 seconds is satisfied. Note that t1 and t2, and A and T1 are thresholds that are determined in advance according to the size of the outdoor heat exchanger 22, the blowing capacity of the outdoor fan 25, and the like, and are stored in the storage unit 201 in advance. Further, the magnitude relationship between the threshold values is A <C and th <t2 ≦ t1.

  Subsequent to step S104, the control unit 203 switches the four-way switching valve 26 in the direction shown by the solid line in FIG. 1 to reverse the refrigerant circulation direction and turns off the electromagnetic valve SV to close the defrosting operation. Then, the operation state of the air conditioner 1 is switched to the heating operation (return to step S102). During operation in the heating operation mode, steps S102 to S105 are repeated.

  According to the first embodiment, among the capillary tubes CT2 to CT5 provided in the refrigerant inlets E2 to E5 of the paths P2 to P5 that do not include the bypass pipe 220, the capillary tube CT2 that minimizes the refrigerant flow rate during the heating operation is connected. Since the defrosting operation is terminated by defrosting the path P2 that is most difficult to defrost among the paths P2 to P5 that are not easily defrosted because the bypass pipe 220 is not provided, that is, the defrosting operation is completed, the outdoor heat exchanger 22 is surely made. Can be defrosted.

  Further, according to the first embodiment, since the start and end of the defrost operation are determined based on the conditions A1 and B1, respectively, the start and end timings of the defrost operation can be accurately determined. Therefore, since unnecessary defrost operation is not performed, the time of defrost operation can be shortened.

  In this embodiment, during the defrost operation, the air conditioner 1 performs a so-called reverse cycle defrost in which the refrigerant circulation direction in the refrigerant circuit 10 is switched. However, in the present embodiment, the position of the bypass pipe 220 and the position during the defrost operation are performed. The control can also be applied to an air conditioner that performs a positive cycle defrost operation that performs a defrost operation by causing the hot gas discharged from the compressor 21 to flow through the outdoor heat exchanger 22 by bypassing the indoor heat exchanger 32. is there.

<Embodiment 2>
The outdoor unit according to the second embodiment has the same mechanical configuration as the outdoor unit 2 according to the first embodiment, and differs only in the control method. In the second embodiment, the defrosting operation includes an upper defrosting operation (first defrosting operation) performed while maintaining the solenoid valve SV in a closed state, a lower defrosting operation (second defrosting operation) performed with the solenoid valve SV opened, It is performed in two stages. In the upper defrost operation, the defrost of the paths P2 to P5 not including the bypass pipe 220 is completed, and in the lower defrost operation, the defrost of the remaining path P1 including the bypass pipe 220 is completed.

  FIG. 4 is a flowchart illustrating the control performed by the control unit 203 during the defrost operation and the heating operation in the second embodiment. At the time when air conditioning is started in the heating operation mode, the normally closed solenoid valve SV is in a closed state (step S201). The controller 203 monitors the temperature Tb1 of the refrigerant inlet E1 detected by the de-isather thermistor DT1 and the hot gas discharge pressure HP discharged by the compressor 21 during the heating operation. It is determined that the heat exchanger 22 has formed frost, and it is determined that it is time to start the defrost operation (YES in step S202). If the condition A2 is not met, the control unit 203 continues the heating operation while continuing the monitoring (NO in step S202).

  Condition A2 is that (1) Tb1 continuously decreases for frost determination time X minutes, (2) Tb1 is less than frost determination temperature th ° C, and (3) discharge pressure HP is less than frost determination pressure value C. This is a case where all three conditions are satisfied. Note that X, th, and C are thresholds determined in advance according to the size of the outdoor heat exchanger 22, the blowing capacity of the outdoor fan 25, and the like, and are stored in the storage unit 201 in advance.

  Following step S202, the control unit 203 keeps the solenoid valve SV closed, switches the four-way switching valve 26 in the direction shown by the broken line in FIG. 1 to reverse the refrigerant circulation direction, and starts the upper defrost operation. (Step S203). The control unit 203 monitors the duration of the upper defrost operation based on the clock signal output from the time measuring unit 202, and also detects the temperature Tb2 of the refrigerant inlet E2 detected by the deisathermistor DT2 and the hot gas discharged from the compressor 21. The discharge pressure HP is monitored, and when the condition B2 is satisfied, it is determined that it is time to end the upper defrost operation (YES in step S204). When the condition B2 is not met, the control unit 203 continues the upper defrost operation while continuing the monitoring (NO in step S204).

  Conditions B2 are: (1) Tb2 exceeds the second end determination temperature t2, (2) the discharge pressure HP exceeds the first end determination pressure value A (Mpa), and (3) the duration is determined to be the first end. This is a case where one of the three conditions of elapse of time T1 seconds is satisfied. Note that t2, A, and T1 are thresholds that are determined in advance according to the size of the outdoor heat exchanger 22, the blowing capacity of the outdoor fan 25, and the like, and are stored in the storage unit 201 in advance.

  Following the upper defrost operation, the control unit 203 turns on the electromagnetic valve SV to open the lower defrost operation (step S205). The control unit 203 monitors the duration time of the lower defrost operation based on the clock signal output from the time measuring unit 202, and monitors Tb1 and the discharge pressure HP of the hot gas discharged from the compressor 21, to satisfy the condition. When it corresponds to C, it is determined that it is time to end the lower defrost operation (YES in step S206). When the condition C is not satisfied, the control unit 203 continues the lower defrost operation while continuing the monitoring (NO in step S206).

  Condition C is (1) Tb1 exceeds the first end determination temperature t1, (2) the discharge pressure HP exceeds the second end determination pressure value B (Mpa), and (3) the duration is determined to be the second end. This is a case where any one of the three conditions of elapse of time T2 seconds is satisfied. Note that t1, B, and T2 are threshold values that are determined in advance according to the size of the outdoor heat exchanger 22, the blowing capacity of the outdoor fan 25, and the like, and are stored in the storage unit 201 in advance. Further, the magnitude relation between the above threshold values is A <B <C and th <t2 ≦ t1.

  Subsequent to step S206, the control unit 203 switches the four-way switching valve 26 in the direction shown by the solid line in FIG. 1 to reverse the refrigerant circulation direction and turns off the electromagnetic valve SV to close the defrost operation. (Step S207), and the operation state of the air conditioner 1 is switched to the heating operation (return to Step S202). During operation in the heating operation mode, steps S202 to S207 are repeated.

  According to the second embodiment, the defrosting other than the path P1 that is most difficult to be defrosted in the upper defrost operation is completed and the path P1 that is least likely to be defrosted in the lower defrost operation is intensively defrosted. The heat exchanger 22 can be defrosted, and the defrost time can be shortened as compared with the first embodiment.

  Furthermore, according to the second embodiment, the start and end of the upper defrost operation are determined based on the conditions A2 and B2, respectively, and the end of the lower defrost operation subsequent to the upper defrost operation is determined based on the condition C. It is possible to accurately determine the start and end timing of the defrost operation. Therefore, since unnecessary defrost operation is not performed, the time of defrost operation can be shortened.

<Embodiment 3>
The outdoor unit 2 ′ according to the third embodiment has the same configuration as that of the outdoor unit 2 according to the first and second embodiments (not shown) except that the de-isather thermistor DT1 is omitted. The control performed by the control unit 203 during the defrost operation and the heating operation is simplified compared to the control in the first embodiment.

  FIG. 5 is a flowchart illustrating the control performed by the control unit 203 during the defrost operation and the heating operation in the third embodiment. At the time when the operation of the air conditioner 1 ′ including the outdoor unit 2 ′ is started in the heating operation mode, the normally closed solenoid valve SV is in a closed state (step S <b> 301). The control unit 203 monitors the temperature Tb2 of the refrigerant inlet E2 detected by the de-isather thermistor DT2 during the heating operation, determines that the outdoor heat exchanger 22 is frosted when the condition A3 is satisfied, and starts the defrost operation. It is determined that the timing is reached (YES in step S302). Condition A3 is a case where Tb2 continuously decreases for frost determination time X minutes and Tb2 becomes less than the frost determination temperature th ° C. Note that X and th are threshold values determined according to the size of the outdoor heat exchanger 22, the blowing capacity of the outdoor fan 25, and the like, as in the first and second embodiments, and are stored in the storage unit 201 in advance.

  Subsequent to step S302, the control unit 203 switches the four-way switching valve 26 in the direction indicated by the broken line in FIG. 1 to reverse the refrigerant circulation direction, and turns on the electromagnetic valve SV to open the defrost operation. (Step S303). The control unit 203 monitors the duration of the defrost operation based on the clock signal output from the time measuring unit 202, and determines that it is the timing to end the defrost operation when the condition B3 is satisfied (YES in step S304). . Condition B3 is a case where the duration exceeds the end determination time T1 seconds. T1 is a threshold value that is stored in advance in the storage unit 201 and that is predetermined according to the size of the outdoor heat exchanger 22, the blowing capacity of the outdoor fan 25, and the like, and the path P2 that is most difficult to be defrosted during the defrost operation. The time is surely defrosted.

  Subsequent to step S304, the control unit 203 switches the four-way switching valve 26 in the direction shown by the solid line in FIG. 1 to reverse the refrigerant circulation direction and turns off the electromagnetic valve SV to close the defrosting operation. Then, the operation state of the air conditioner 1 ′ is switched to the heating operation (return to step S302). During operation in the heating operation mode, steps S302 to S305 are repeated.

  According to the third embodiment, only one DT2 is required for the deisathermistor, and the control is simplified as compared with the control in the first and second embodiments. Therefore, the outdoor unit can be manufactured at a lower cost. Become. When air conditioning is performed under conditions in which the uniformity of the evaporation temperature of the refrigerant at the outlets of the paths P1 to P5 is not easily impaired, for example, when the outdoor temperature changes little or the air conditioning temperature is fixed, etc. Form 3 is a preferred embodiment.

<Embodiment 4>
Embodiment 4 is an embodiment in the case where the air conditioner 1 is limited to an air conditioner that performs reverse cycle defrosting. FIG. 6 is a schematic diagram illustrating details of a piping configuration between the electronic expansion valve 24 and the outdoor heat exchanger 22 in the outdoor unit 2A according to the fourth embodiment. The same code | symbol is attached | subjected about the structure same as the outdoor unit 2 which concerns on Embodiment 1 and 2. FIG. In addition to the configuration of the outdoor unit 2, the outdoor unit 2A is provided in the inter-pass piping 230 that bypasses the refrigerant flowing through the capillary tube CT2 connected to the path P2 during the defrost operation to the path P1, and the inter-pass piping 230. And a capillary tube 231 (flow restriction mechanism).

  One end of the inter-pass piping 230 is connected between the refrigerant inlet E1 and the capillary tube CT1, and the other end is connected between the refrigerant inlet E2 and the capillary tube CT2. The capillary tube 231 is selected such that its frictional resistance is smaller than that of the capillary tubes CT1 and CT2. For this reason, the capillary tube 231 having a low frictional resistance is easier to pass through the refrigerant than the capillary tubes CT1 and CT2 having a large frictional resistance, and therefore, from the refrigerant inlet E2 during the defrost operation (becomes the refrigerant outlet during the defrost operation). The refrigerant flowing out bypasses the capillary tube CT2 and flows to the path P1, and is further guided to the bypass pipe 220.

  That is, in the outdoor unit 2A, when the control unit 203 opens the solenoid valve SV provided in the bypass pipe 220 during the defrost operation, in addition to the refrigerant flowing out from the refrigerant inlet E1, the refrigerant flowing out from the refrigerant inlet E2 also Bypassed to the bypass pipe 220. Therefore, at the time of defrost operation, the refrigerant | coolant flow rate of the path | pass P1 and the path | pass P2 increases more than the path | pass P3-P5 in which refrigerant | coolant flow volume is restrict | limited by capillary tube CT3-CT5. Therefore, since the defrost efficiency of the paths P1 and P2 is improved, the defrost operation time can be shortened compared to the outdoor unit 2. In the fourth embodiment, the control performed by the control unit 203 during the defrosting operation and the heating operation is the same control as in the first or second embodiment.

  Thus, in the outdoor unit 2A, not only the bypass pipe 220 but also the inter-pass pipe 230 is provided, so that not only the path P1 with the smallest refrigerant flow rate during heating operation but also the path P2 with the second smallest refrigerant flow rate. The hot gas flow rate can be increased during defrost operation. Therefore, compared with the configuration of the outdoor unit 2 including only the bypass pipe 220, the efficiency of the defrost operation can be further improved. Other effects are the same as those in the first or second embodiment.

  As mentioned above, although the outdoor unit which concerns on Embodiment 1-4 of this invention was demonstrated, this invention is not limited to these embodiment, For example, the following modified embodiments can also be taken.

  (1) In the outdoor unit 2A according to the fourth embodiment, a bypass pipe 220B that bypasses the capillary tube CT2 may be provided instead of the inter-pass pipe 230 (outdoor unit 2B shown in FIG. 7). The bypass pipe 220B includes an electromagnetic valve SV2 and a capillary tube 221 provided at a position upstream of the electromagnetic valve SV2 in the refrigerant flow direction during defrost operation. Further, the frictional resistance of the capillary tube 221 is set to a value smaller than any of the capillary tubes CT1 to CT5. Also with the outdoor unit 2B, the hot gas flow rate can be increased during the defrost operation not only in the path P1 having the smallest refrigerant flow rate during the heating operation but also in the path P2 having the second smallest refrigerant flow rate. In addition, if bypass piping and a deisather thermistor are further added after the path P3, the paths P1 to P5 can be defrosted more uniformly.

  (2) In the outdoor unit according to Embodiments 1 to 3, one end of the bypass pipe 220 is connected between the flow divider 23 and the capillary tube CT1, and the other end is connected between the capillary tube CT1 and the refrigerant inlet E1. You may make it do (outdoor unit 2C shown in FIG. 8). Note that the outdoor unit 2C does not include the inter-pass piping 230, but also in the outdoor unit according to the fourth embodiment including the inter-pass piping 230, one end of the bypass piping 220 is connected between the flow divider 23 and the capillary tube CT1. The other end can be connected between the capillary tube CT1 and the refrigerant inlet E1.

CT1-5 Capillary tube (flow rate adjustment mechanism)
DT1, DT2 Deisarmistor (first and second temperature detector, inlet temperature detector)
E1-5 Refrigerant inlet SV, SV1, SV2 Solenoid valve (opening / closing mechanism)
DESCRIPTION OF SYMBOLS 1, 1 'Air conditioner 2, 2', 2A, 2B, 2C, 2D Outdoor unit 20 Casing 21 Compressor 22 Outdoor heat exchanger 23 Divider (Diversion mechanism)
24 Electronic expansion valve (pressure reduction mechanism)
25 outdoor fan 200 controller 201 storage unit 202 timing unit 203 control unit 211 high pressure sensor (pressure detection unit)
220, 220B Bypass piping 230 Inter-pass piping 231 Capillary tube (flow restriction mechanism)

Claims (9)

A heat exchanger (22) having a plurality of paths (P1-5) and functioning as an evaporator during heating operation;
A fan (25) for blowing outdoor air to the heat exchanger (22);
A casing (20) that houses at least the heat exchanger (22) and the fan (25);
A decompression mechanism (24) for decompressing the refrigerant condensed in the condenser during heating operation;
A diversion mechanism (23) for diverting the refrigerant depressurized by the depressurization mechanism (24) during heating operation to the inlets (E1-5) of the plurality of paths (P1-5);
A flow rate adjusting mechanism that is provided between the flow dividing mechanism (23) and each of the inlets (E1 to 5), and adjusts the flow rate of the refrigerant flowing into each of the inlets (E1 to 5) during heating operation to a different flow rate. (CT1-5),
A bypass pipe (220) for bypassing a flow rate adjusting mechanism (CT1) for adjusting the flow rate to a predetermined value or less in the flow rate adjusting mechanisms (CT1 to 5) during defrost operation;
An opening / closing mechanism (SV) provided in the bypass pipe (220) for opening and closing the bypass pipe (220);
A control unit (203) for controlling each operation mechanism at the time of defrost operation,
The control unit (203) is an outdoor unit of an air conditioner that opens the opening / closing mechanism (SV) during at least a part of the period during the defrost operation.   One end of the bypass pipe (220) is connected between the pressure reducing mechanism (24) and the flow dividing mechanism (23), and the other end is between the flow rate adjusting mechanism (CT1) and the inlet (E1). The outdoor unit of the air conditioner of Claim 1 connected to.   One end of the bypass pipe (220) is connected between the flow dividing mechanism (23) and the flow rate adjusting mechanism (CT1), and the other end is between the flow rate adjusting mechanism (CT1) and the inlet (E1). The outdoor unit of the air conditioner of Claim 1 connected to. The fan (25) is provided on the upper part of the casing (20),
The plurality of paths (P1 to 5) of the heat exchanger (22) are formed in parallel in the vertical direction of the casing (20),
The air conditioner according to any one of claims 1 to 3, wherein the flow rate adjusting mechanism (CT1 to 5) is configured to reduce the refrigerant flow rate in a path disposed closer to the lower side in the vertical direction. Outdoor unit.   The outdoor unit of an air conditioner according to claim 4, wherein the bypass pipe (220) is provided only in the flow rate adjusting mechanism (CT1) connected to a path arranged at the lowest position. An air conditioner outdoor unit that performs reverse cycle defrost operation,
During the reverse cycle defrost operation, the refrigerant flowing through the flow rate adjusting mechanism (CT2) connected to one of the plurality of paths (P1 to P5) is changed to another path (P1) different from the path (P2). Between-pass piping (230) to be bypassed
A flow restriction mechanism (231) provided in the inter-pass pipe (230) and restricting a refrigerant flow rate flowing through the inter-pass pipe (230),
The inter-pass pipe (230) is at least a flow rate adjustment that makes the refrigerant flow the smallest in the flow rate adjustment mechanism (CT2) that makes the refrigerant flow rate the second smallest among the flow rate adjustment mechanisms (CT1 to 5). The outdoor unit of the air conditioner of any one of Claims 1-5 arrange | positioned in the position bypassed by the path | pass (P1) to which a mechanism (CT1) is connected. Of the flow rate adjustment mechanisms (CT2-5) provided at the inlets of the paths (P2-5) that do not include the bypass pipe (220), the flow rate adjustment mechanism (CT2) that reduces the refrigerant flow rate most during heating operation is connected. An inlet temperature detector (DT2) provided at the inlet (E2) of the path (P2) to detect the temperature of the inlet (E2);
A timing unit (202),
The control unit (203)
The temperature of the inlet (E2) detected by the inlet temperature detector (DT2) continuously decreases over a frosting determination time which is a predetermined time,
And when the temperature of the said inlet (E2) becomes less than the frosting determination temperature which is predetermined temperature, the said opening-and-closing mechanism (SV) is made into an open state, defrost operation is started,
7. The defrosting operation according to any one of claims 1 to 6, wherein when the duration time of the defrost operation exceeds an end determination time which is a predetermined time, the opening and closing mechanism (SV) is closed to end the defrost operation. The outdoor unit of the air conditioner described. Provided at the inlet (E1) of the path (P1) to which the flow rate adjusting mechanism (CT1) that reduces the refrigerant flow rate is the lowest among the flow rate adjusting mechanisms (CT1 to 5) during the heating operation, the inlet (E1 ) A first temperature detector (DT1) that detects a first inlet temperature that is a temperature of
Of the flow rate adjustment mechanisms (CT2 to 5) provided at the inlets (E2 to 5) of the paths (P2 to P5) not provided with the bypass pipe (220), the flow rate adjustment mechanism that minimizes the refrigerant flow rate during heating operation. A second temperature detector (DT2) provided at the inlet (E2) of the path (P2) to which (CT2) is connected, and detecting a second inlet temperature which is the temperature of the inlet (E2);
A pressure detector (211) for detecting the discharge pressure of the refrigerant discharged from the compressor (21);
A timing unit (202),
The control unit (203)
The first inlet temperature continuously decreases over a frosting determination time which is a predetermined time,
And the first inlet temperature is less than a frosting determination temperature that is a predetermined temperature,
And when the said discharge pressure becomes less than the frosting determination pressure value which is a predetermined pressure value, the defrosting operation is started with the opening / closing mechanism (SV) opened,
During the defrost operation,
When the duration of the defrost operation exceeds an end determination time which is a predetermined time,
Alternatively, the first end temperature exceeds a first end determination temperature that is a predetermined first temperature, and the second inlet temperature is a second end temperature that is a predetermined second temperature. If you exceed
Or, when the discharge pressure exceeds an end determination pressure value that is a predetermined pressure value,
The outdoor unit of the air conditioner according to any one of claims 1 to 6, wherein the defrosting operation is ended by closing the opening / closing mechanism (SV) when at least one of them is satisfied. The bypass pipe (220) is provided only in the flow rate adjustment mechanism (CT1) that reduces the refrigerant flow rate most among the flow rate adjustment mechanisms (CT1 to 5) during the defrost operation,
Provided at the inlet (E1) of the path (P1) to which the flow rate adjusting mechanism (CT1) that reduces the refrigerant flow rate is the lowest among the flow rate adjusting mechanisms (CT1 to 5) during the heating operation, and the temperature of the inlet A first temperature detector (DT1) for detecting a first inlet temperature which is
Provided at the inlet (E2) of the path (P2) to which the flow rate adjusting mechanism (CT2) for decreasing the refrigerant flow rate secondly among the flow rate adjusting mechanisms (CT1 to 5) during the heating operation is connected. A second temperature detector (DT2) for detecting a second inlet temperature which is the temperature of
A pressure detector (211) for detecting the discharge pressure of the refrigerant discharged from the compressor (21);
A timing unit (202),
The control unit (203)
The first inlet temperature continuously decreases over a frosting determination time which is a predetermined time,
And the first inlet temperature is less than a frosting determination temperature that is a predetermined temperature,
And when the said discharge pressure becomes less than the frosting determination pressure value which is a predetermined pressure value, the 1st defrost operation which is a defrost operation performed by maintaining the said opening-closing mechanism (SV) in a closed state is started. And
During the first defrost operation,
When the duration of the first defrost operation exceeds a first end determination time which is a predetermined first time,
Alternatively, when the second inlet temperature exceeds a second end determination temperature that is a predetermined second temperature,
Alternatively, when the discharge pressure exceeds a first end determination pressure value that is a predetermined first pressure value,
The first defrost operation is terminated when at least one of
Following the first defrost operation, a second defrost operation, which is a defrost operation in which the opening / closing mechanism (SV) is opened, is started,
During the second defrost operation,
When the duration of the second defrost operation exceeds a second end determination time that is a predetermined second time,
Alternatively, when the first inlet temperature exceeds a first end determination temperature that is a predetermined first temperature,
Alternatively, when the discharge pressure exceeds a second end determination pressure value that is a predetermined second pressure value,
The air conditioner outdoor unit according to any one of claims 1 to 6, wherein the second defrosting operation is ended by closing the opening / closing mechanism (SV) when at least one of the above-described cases is satisfied.

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