JP2015068610A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner capable of suppressing temperature rise in electric components, and capable of reducing the risk that execution time of a defrosting operation is extended.SOLUTION: The air conditioner includes: a casing 30a; an outdoor heat exchanger 33; an outdoor fan 34; and an electric component box 70. During a normal operation, the outdoor fan 34 rotates so as to take in the air from the outside of the casing 30a and to pass it to the outdoor heat exchanger 33. In the electric component box 70, a heat sink 71 is provided for letting generated heat of the electric components escape to the outside. This air conditioner performs a defrosting time reverse rotation control for rotating the outdoor fan 34 in a direction opposite from that of the normal operation during a defrosting operation so as to suppress the air passing through the outdoor heat exchanger 33 and to agitate the air inside the casing 30a.

Description

  The present invention relates to an air conditioner that performs a defrosting operation.

  2. Description of the Related Art Conventionally, there is an air conditioner that performs a defrosting operation for removing frost generated in an outdoor heat exchanger during a heating operation. Some of these air conditioners do not rotate an outdoor fan for passing outside air through the outdoor heat exchanger during the defrosting operation in order to promote removal of frost formation. However, when the defrosting operation is performed without rotating the outdoor fan, there is a problem in that the amount of heat dissipated by the electrical component mounted on the control board or the like is reduced and the temperature of the electrical component is increased.

  As one of countermeasures against this, for example, in the air conditioner disclosed in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2009-287843), the temperature of the electrical component rises by rotating the outdoor fan during the defrosting operation. It is restrained to do.

  By the way, in the air conditioner disclosed in Patent Document 1, since the outdoor fan is rotated during the defrosting operation as in the normal operation, air passes through the outdoor heat exchanger as in the normal operation. It is thought that there is. Then, even during the defrosting operation, heat exchange is performed between the refrigerant flowing through the outdoor heat exchanger and the air in the outdoor heat exchanger.

  Here, when the end of the defrosting operation is determined based on the temperature of the refrigerant flowing through the outdoor heat exchanger, that is, the temperature of the refrigerant flowing through the outdoor heat exchanger is set to a predetermined temperature (hereinafter referred to as the defrosting operation end temperature). Then, when the defrosting operation is finished, when heat exchange is performed between the refrigerant flowing through the outdoor heat exchanger and the air in the outdoor heat exchanger during the defrosting operation, the temperature of the outdoor heat exchanger is finished. The time until it reaches the temperature becomes long, and the execution time of the defrosting operation is extended.

  Then, the subject of this invention is providing the air conditioning apparatus which can reduce the possibility that the temperature rise of an electrical component may be suppressed and the execution time of a defrost operation may be extended.

  An air conditioner according to a first aspect of the present invention is an air conditioner that performs a normal operation and a defrosting operation, and includes a casing, an outdoor heat exchanger, an outdoor fan, and an electrical component box. The outdoor heat exchanger is disposed in the casing. The outdoor fan is disposed in the casing. In addition, during normal operation, the outdoor fan rotates so as to take in air from outside the casing and pass it through the outdoor heat exchanger. The electrical component box is disposed in the casing. The electrical component box stores electrical components for controlling devices including the outdoor fan. Furthermore, the electrical component box is provided with a heat sink for releasing the heat generated by the electrical component to the outside. And this air conditioning apparatus performs reverse rotation control at the time of a defrost at the time of a defrost operation. Reverse rotation control during defrosting is a control that rotates the outdoor fan in reverse to the normal operation so as to suppress air from passing through the outdoor heat exchanger and to stir the air in the casing during the defrosting operation. It is.

  In the air conditioner according to the first aspect of the present invention, air is prevented from passing through the outdoor heat exchanger by performing reverse rotation control during defrosting during the defrosting operation. Heat exchange between the refrigerant flowing through the heat exchanger and the air can be suppressed, and the time until the temperature of the refrigerant flowing through the outdoor heat exchanger reaches the defrosting operation end time becomes longer. Can be prevented. In addition, since reverse rotation control during defrosting is performed during the defrosting operation, the air in the casing is agitated, so the air can be applied to the heat sink to cool the heat sink, and the heat generated by the electrical components is released to the outside. be able to.

  Thereby, it is possible to suppress the temperature rise of the electrical component and reduce the possibility that the execution time of the defrosting operation is extended.

  The normal operation here includes at least a cooling operation.

  The air conditioner according to the second aspect of the present invention is the air conditioner according to the first aspect, wherein when the temperature of the heat sink detected by the heat sink temperature sensor provided on the heat sink is equal to or higher than a predetermined value, defrosting is performed. Reverse rotation control is performed. In this air conditioner, when the temperature of the heat sink becomes equal to or higher than a predetermined value, the reverse rotation control at the time of defrosting is performed. Therefore, the reverse rotation control at the time of defrosting is performed continuously from the start to the end of the defrost operation. Compared with, power consumption can be suppressed.

  In the air conditioner according to the first aspect of the present invention, it is possible to suppress the temperature rise of the electrical component and reduce the possibility that the execution time of the defrosting operation is extended.

  In the air conditioner according to the second aspect of the present invention, the power consumption can be suppressed.

The schematic refrigerant circuit figure of the air conditioning apparatus which concerns on one Embodiment of this invention. Schematic which shows the internal structure of an outdoor unit. It is a key map of an outdoor unit, and is a figure for explaining air flow. It is a key map of an outdoor unit, and is a figure for explaining air flow. The control block diagram of the control unit with which an air conditioning apparatus is provided. The flowchart which shows the flow of a process of a control unit.

  Hereinafter, an embodiment of an air-conditioning apparatus according to the present invention will be described with reference to the drawings. In addition, the specific structure of the air conditioning apparatus which concerns on this invention is not restricted to the following embodiment, In the range which does not deviate from the summary of invention, it can change suitably.

(1) Overall Configuration FIG. 1 is a schematic refrigerant circuit diagram of an air conditioner 100 according to an embodiment of the present invention. The air conditioner 100 is an air conditioner that can be operated by switching between a cooling operation and a heating operation by performing a vapor compression refrigeration cycle.

  As shown in FIG. 1, the air conditioner 100 mainly includes an indoor unit 20 and an outdoor unit 30.

  The indoor unit 20 and the outdoor unit 30 constitute a refrigerant circuit 80 by being connected by a refrigerant pipe as a communication pipe. The refrigerant circuit 80 includes a main refrigerant circuit 81 and a discharge-suction bypass circuit 50. The main refrigerant circuit 81 is configured by a compressor 31, which will be described later, an outdoor heat exchanger 33, a main valve 35, and the indoor heat exchanger 21 connected by a refrigerant pipe. The air conditioner 100 performs normal operation by circulating the refrigerant in the main refrigerant circuit 81. In the present embodiment, the normal operation includes a heating operation and a cooling operation. For example, when performing the heating operation, the air conditioning apparatus 100 circulates the refrigerant in the order of the compressor 31, the indoor heat exchanger 21, the main valve 35, and the outdoor heat exchanger 33. When performing the cooling operation, the air conditioner 100 circulates the refrigerant in the order of the compressor 31, the outdoor heat exchanger 33, the main valve 35, and the indoor heat exchanger 21.

  Further, the discharge-suction bypass circuit 50 is connected to the main refrigerant circuit 81 so as to bypass a suction pipe 37 and a discharge pipe 38 of the compressor 31 described later. Then, the air conditioner 100 circulates the refrigerant in the main refrigerant circuit 81 and the discharge-suction bypass circuit 50 to remove frost attached to the outdoor heat exchanger 33 while heating the room that is the target of air conditioning. To perform defrosting operation. The discharge-suction bypass circuit 50 is normally not used during cooling operation or heating operation but is used when defrosting operation is performed.

  In this air conditioner 100, for example, an HFC (hydrofluorocarbon) refrigerant such as R32 or R410A is enclosed as a refrigerant. However, the type of the refrigerant is not limited to the HFC refrigerant.

(2) Detailed configuration (2-1) Indoor unit The indoor unit 20 is installed indoors. The indoor unit 20 includes an indoor heat exchanger 21, an indoor fan 22, and various temperature sensors.

  The indoor heat exchanger 21 is a cross-fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of heat transfer fins. The indoor heat exchanger 21 functions as an evaporator that evaporates the refrigerant during the cooling operation, and functions as a condenser that condenses the high-pressure refrigerant during the heating operation.

  The indoor fan 22 sucks indoor air into the indoor unit 20, causes the air sucked in the indoor heat exchanger 21 and the refrigerant to exchange heat, and supplies the air after heat exchange with the refrigerant to the room. That is, the indoor fan 22 is a fan that supplies indoor air to the indoor heat exchanger 21 as a heating source or cooling source for the refrigerant flowing through the indoor heat exchanger 21. In addition, as the indoor fan 22, a centrifugal fan, a multiblade fan, etc. are used, for example.

  The various temperature sensors include an indoor heat exchange temperature sensor 61 and an indoor temperature sensor 62 (see FIG. 5). The indoor heat exchanger temperature sensor 61 is a thermistor that detects the temperature of the refrigerant flowing through the indoor heat exchanger 21. The indoor heat exchanger temperature sensor 61 is attached to the indoor heat exchanger 21. The room temperature sensor 62 is a thermistor for detecting the room temperature.

(2-2) Outdoor Unit FIG. 2 is a schematic diagram showing the internal structure of the outdoor unit 30. The outdoor unit 30 is installed outdoors. The outdoor unit 30 includes a rectangular parallelepiped casing 30a. An air inlet (not shown) for sucking air into the casing 30a is provided on the back surface of the casing 30a, and an air outlet for blowing out the air sucked into the casing 30a on the front surface of the casing 30a. (Not shown) is provided. Moreover, the inside of the casing 30a is divided | segmented into fan room S1 and machine room S2 by the partition plate 30b extended along a perpendicular direction. An outdoor heat exchanger 33 and an outdoor fan 34 are disposed on the blower chamber S1 side, and a compressor 31, a four-way switching valve 32, and a main valve 35 are disposed on the machine chamber S2 side. .

  The outdoor unit 30 mainly includes a compressor 31, a four-way switching valve 32, an outdoor heat exchanger 33, an outdoor fan 34, a main valve 35, a discharge-suction bypass circuit 50, an electrical component box 70, and various temperature sensors. have.

(2-2-1) Compressor The compressor 31 is a device that compresses the low-pressure refrigerant in the refrigeration cycle until the pressure becomes high. The compressor 31 sucks the low-pressure refrigerant from the suction pipe 37, compresses the refrigerant, and discharges the high-pressure refrigerant. The compressor 31 has a sealed structure in which a rotary type or scroll type positive displacement compression element (not shown) is rotationally driven by a compressor motor 31m controlled by an inverter. A suction pipe 37 is connected to the compressor 31 on the suction side, and a discharge pipe 38 is connected to the discharge side.

  The suction pipe 37 is a refrigerant pipe that connects the suction side of the compressor 31 and the four-way switching valve 32. The suction pipe 37 is provided with a small-volume accumulator 36 attached to the compressor 31. The discharge pipe 38 is a refrigerant pipe that connects the discharge side of the compressor 31 and the four-way switching valve 32. The suction pipe 37 and the discharge pipe 38 are connected by a bypass pipe 51 that constitutes a discharge-suction bypass circuit 50.

(2-2-2) Four-way switching valve The four-way switching valve 32 is a switching valve for switching the direction in which the refrigerant flows in the main refrigerant circuit 81. The four-way switching valve 32 is connected to the discharge side of the compressor 31 and the indoor heat exchanger 21, and is connected to the outdoor heat exchanger 33 and the suction side of the compressor 31 (see the solid line in FIG. 1). ) And the discharge side of the compressor 31 and the outdoor heat exchanger 33, and the second state (see the broken line in FIG. 1) in which the indoor heat exchanger 21 and the suction side of the compressor 31 are connected. By switching, the circulation direction of the refrigerant in the main refrigerant circuit 81 is configured to be reversible.

  During the heating operation, the four-way switching valve 32 is in the first state, and the refrigerant discharged from the compressor 31 is condensed in the indoor heat exchanger 21 to become liquid refrigerant, and after being decompressed in the main valve 35, The water is evaporated by the outdoor heat exchanger 33 and sucked into the compressor 31 through the accumulator 36. On the other hand, during the cooling operation, the four-way switching valve 32 is in the second state, and the refrigerant discharged from the compressor 31 is condensed by the outdoor heat exchanger 33 to become liquid refrigerant, and after being decompressed by the main valve 35, It evaporates in the indoor heat exchanger 21 and is sucked into the compressor 31 through the accumulator 36.

(2-2-3) Outdoor Heat Exchanger The outdoor heat exchanger 33 is a cross-fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of heat transfer fins. The outdoor heat exchanger 33 is a heat exchanger that functions as a refrigerant condenser that uses outside air as a cooling source during cooling operation, and that functions as a refrigerant evaporator that uses outside air as a heating source during heating operation.

(2-2-4) Main valve The main valve 35 is a motor valve with variable opening, and the main valve 35 in this embodiment is an electric expansion valve. The opening degree of the main valve 35 is adjusted and controlled by the control unit 40, and the pressure and flow rate of the refrigerant flowing through the main refrigerant circuit 81 are adjusted. During the cooling operation, the main valve 35 expands the refrigerant flowing from the outdoor heat exchanger 33 that functions as a condenser to the indoor heat exchanger 21 that functions as an evaporator. Further, during the heating operation, the main valve 35 expands the refrigerant flowing from the indoor heat exchanger 21 functioning as a condenser to the outdoor heat exchanger 33 functioning as an evaporator.

(2-2-5) Discharge-Suction Bypass Circuit As described above, the discharge-suction bypass circuit 50 is a circuit used during a defrosting operation with room heating, and is connected to the main refrigerant circuit 81. In the defrosting operation in the present embodiment, the refrigerant flows in the main refrigerant circuit 81 in the same direction as in the heating operation, and this defrosting operation is hereinafter referred to as a normal cycle defrosting operation.

  The discharge-suction bypass circuit 50 includes a bypass pipe 51 and an overheat valve 52. The bypass pipe 51 connects the suction pipe 37 and the discharge pipe 38 of the compressor 31. Specifically, the bypass pipe 51 connects the suction pipe 37 upstream of the accumulator 36 (four-way switching valve 32 side) and the discharge pipe 38.

  The overheat valve 52 is, for example, an electric valve with a variable opening. The opening degree of the superheat valve 52 is adjusted and controlled by the control unit 40 to adjust the flow rate of the refrigerant flowing through the bypass pipe 51. The overheat valve 52 is closed during the cooling operation or the heating operation, and the refrigerant does not flow through the bypass pipe 51. The overheat valve 52 is opened only during the normal cycle defrosting operation, and bypasses the refrigerant from the discharge side of the compressor 31 to the suction side of the compressor 31.

(2-2-6) Outdoor Fan The outdoor fan 34 includes blades 34a and a fan motor 34m, and the fan motor 34m rotates the blades 34a to generate an air flow. The fan motor 34m is a motor that can rotate forward and backward, and the outdoor fan 34 performs forward rotation operation and reverse rotation operation. An example of the fan motor 34m is one that switches between forward rotation and reverse rotation by reversing the direction of current in the positive and negative directions. In addition, the fan motor 34m in the present embodiment reverses the direction of the current by changing the inverter waveform.

  In the present embodiment, when the fan motor 34m rotates forward, the outdoor fan 34 performs forward rotation operation. Then, when the outdoor fan 34 performs forward rotation operation, as indicated by an arrow F1 in FIG. 3, the outside air is taken into the casing 30a from the air suction port provided on the back surface of the casing 30a, and the outdoor heat exchange is performed. Through the vessel 33, an air flow is generated that is discharged out of the casing 30a from an air outlet provided on the front surface of the casing 30a. For this reason, when the outdoor fan 34 performs a forward rotation operation, the outside air is sucked into the outdoor unit 30, passes through the outdoor heat exchanger 33, and the outside air sucked in the outdoor heat exchanger 33 exchanges heat with the refrigerant. Then, the outside air after the heat exchange is discharged to the outside, that is, the outside air as a cooling source or a heating source of the refrigerant flowing in the outdoor heat exchanger 33 is supplied to the outdoor heat exchanger 33.

  On the other hand, the outdoor fan 34 performs reverse rotation operation by the reverse rotation of the fan motor 34m. And when the outdoor fan 34 performs reverse rotation operation, as shown to the arrow F2 of FIG. 4, the air flow which circulates through the inside of the casing 30a arises. At this time, the air flow is such that the outside air is taken into the casing 30a and discharged to the outside of the casing 30a through the outdoor heat exchanger 33, that is, the air flow hardly occurs as shown by the arrow F1 in FIG. It has become. For this reason, when the outdoor fan 34 performs a reverse rotation operation, it is suppressed that the outdoor air as a cooling source or heating source of the refrigerant flowing through the outdoor heat exchanger 33 is supplied to the outdoor heat exchanger 33. The air in the casing 30a is agitated.

  In addition, when the outdoor fan 34 performs reverse rotation operation, the outdoor fan 34 may be designed so that outside air does not pass through the outdoor heat exchanger 33 at all, so that the execution time of the normal cycle defrosting operation does not increase. The outdoor fan 34 may be designed so that the outside air passes through the outdoor heat exchanger 33.

(2-2-7) Electrical Component Box The electrical component box 70 stores electrical components (not shown) for controlling various devices stored in the outdoor unit 30. The electrical components include power elements, coil components, reactors, and the like that generate heat during operation.

  The electrical component box 70 is formed in a rectangular parallelepiped shape so that the inside becomes a closed space, and is disposed at an upper portion in the casing 30a. Moreover, in this embodiment, as shown in FIG. 2, the electrical component box 70 is arrange | positioned so that the partition plate 30b may be straddled. Specifically, the right end portion of the electrical component box 70 is disposed on the machine room S2 side, and the left end portion of the electrical component box 70 is disposed on the blower chamber S1 side.

  In addition, a heat sink 71 is provided at the left end of the electrical component box 70 to release heat generated by the electrical component to the outside. The heat sink 71 is made of a metal such as aluminum or copper having excellent thermal conductivity, and includes a plate-like base portion 71a and a plurality of plates 71b that are orthogonal to the base portion 71a and arranged in parallel to each other. ing. And in this embodiment, the electrical component box 70 is accommodated in the casing 30a so that the heat sink 71 may be located in the fan room S1 side.

  Note that “the electrical component box 70 configured to be a closed space inside” includes those in which vent holes are formed so that dust and moisture in the electrical component box 70 do not pass.

(2-2-8) Various temperature sensors The outdoor unit 30 has various temperature sensors. The various temperature sensors include an outdoor heat exchange temperature sensor 63, a discharge temperature sensor 64, an outdoor temperature sensor 65, and a heat sink temperature sensor 66. The outdoor heat exchange temperature sensor 63 is a thermistor that detects the temperature of the refrigerant flowing through the outdoor heat exchanger 33. The outdoor heat exchange temperature sensor 63 is attached to the outdoor heat exchanger 33. The discharge temperature sensor 64 is a thermistor that detects the temperature of the refrigerant discharged from the compressor 31. The discharge temperature sensor 64 is provided outside the compressor 31, more specifically, in the discharge pipe 38 near the discharge port of the compressor 31. The outdoor temperature sensor 65 is a thermistor that detects the outside air temperature. The heat sink temperature sensor 66 is a thermistor that detects the temperature of the heat sink 71. The heat sink temperature sensor 66 is attached to the heat sink 71.

(2-3) Control Unit FIG. 5 is a control block diagram of the control unit 40 provided in the air conditioning apparatus 100. As shown in FIG. 5, the control unit 40 is connected to various devices included in the air conditioning apparatus 100, and operates various devices to perform various operations including a cooling operation, a heating operation, a normal cycle defrosting operation, and the like. Take control.

  Further, as shown in FIG. 5, the control unit 40 is connected to an indoor heat exchange temperature sensor 61, an indoor temperature sensor 62, an outdoor heat exchange temperature sensor 63, a discharge temperature sensor 64, an outdoor temperature sensor 65, a heat sink temperature sensor 66, and the like. The compressor motor 31m, the four-way switching valve 32, the fan motor 34m of the outdoor fan 34, the main valve 35, the overheat valve 52, the indoor fan 22, and the like are controlled based on the detection results of the sensors.

  Further, when the control unit 40 determines that frost formation has occurred in the outdoor heat exchanger 33 during the heating operation, the control unit 40 switches the operation of the air conditioner 100 from the heating operation to the normal cycle defrosting operation, and the outdoor heat exchanger When it is determined that the removal of frost in 33 is completed, the operation of the air conditioner 100 is switched from the normal cycle defrosting operation to the heating operation. For example, the control unit 40 switches the operation of the air conditioner 100 from the heating operation to the normal cycle defrosting operation based on the temperature of the refrigerant flowing through the outdoor heat exchanger 33 detected by the outdoor heat exchanger temperature sensor 63. And whether or not to switch from the normal cycle defrosting operation to the heating operation is determined. Specifically, the control unit 40 performs outdoor heat exchange when the temperature of the refrigerant flowing through the outdoor heat exchanger 33 detected by the outdoor heat exchanger temperature sensor 63 during the heating operation becomes equal to or lower than the defrosting operation start temperature. It is judged that frosting has occurred in the vessel 33, and the operation of the air conditioner 100 is switched from the heating operation to the normal cycle defrosting operation. The control unit 40 also performs outdoor heat exchange when the temperature of the refrigerant flowing through the outdoor heat exchanger 33 detected by the outdoor heat exchanger temperature sensor 63 during the positive cycle defrosting operation is equal to or higher than the defrosting operation end temperature. It is determined that the removal of frost in the vessel 33 has been completed, and the operation of the air conditioner 100 is switched from the normal cycle defrosting operation to the heating operation.

  Furthermore, the control unit 40 determines whether or not the temperature of the heat sink 71 detected by the heat sink temperature sensor 66 is equal to or higher than a predetermined value, for example, every predetermined time during the positive cycle defrosting operation. And when it determines with the temperature of the heat sink 71 being more than predetermined value during a normal cycle defrost operation, reverse rotation control at the time of defrost is performed. When the defrosting reverse rotation control is executed, the outdoor fan 34 rotates in the reverse direction to the normal operation, that is, performs the reverse rotation operation.

  In addition, the said predetermined value should just be set based on the temperature which can protect an electrical component.

(3) Operation | movement of an air conditioning apparatus Next, operation | movement (except operation | movement at the time of defrosting) of the air conditioning apparatus 100 is demonstrated using FIG. The operation of the air conditioning apparatus 100 is executed by the control unit 40. The air conditioner 100 can perform normal operation including cooling operation and heating operation. In this embodiment, in both the heating operation and the cooling operation, the control unit 40 operates the compressor 31, the indoor fan 22, and the outdoor fan 34 so that the indoor temperature becomes the target temperature (set temperature). While controlling, the opening degree of the main valve 35 is adjusted based on the refrigerant temperature on the discharge side of the compressor 31 detected by the discharge temperature sensor 64. During normal operation, the control unit 40 controls the operation of the fan motor 34m so that the outdoor fan 34 performs forward rotation.

(3-1) Heating Operation During the heating operation, the four-way switching valve 32 is switched to the first state (the state indicated by the solid line in FIG. 1).

  In the main refrigerant circuit 81, the low-pressure gas refrigerant in the refrigeration cycle is sucked into the compressor 31 and is compressed until it reaches a high pressure in the refrigeration cycle, and then discharged. The high-pressure gas refrigerant discharged from the compressor 31 is sent to the indoor heat exchanger 21 through the discharge pipe 38 and the four-way switching valve 32. The high-pressure gas refrigerant sent to the indoor heat exchanger 21 radiates heat by exchanging heat with indoor air supplied as a cooling source by the indoor fan 22 in the indoor heat exchanger 21 to become a high-pressure liquid refrigerant. . Thereby, indoor air is heated and indoor heating is performed by being supplied indoors. The high-pressure liquid refrigerant radiated by the indoor heat exchanger 21 is sent to the main valve 35. The high-pressure liquid refrigerant sent to the main valve 35 is depressurized to a low pressure in the refrigeration cycle. The refrigerant decompressed by the main valve 35 is sent to the outdoor heat exchanger 33. The low-pressure liquid refrigerant sent to the outdoor heat exchanger 33 exchanges heat with the outside air supplied as a heating source by the outdoor fan 34 in the outdoor heat exchanger 33 and evaporates to become a low-pressure gas refrigerant. The low-pressure refrigerant evaporated in the outdoor heat exchanger 33 is sent to the suction pipe 37 through the four-way switching valve 32 and is sucked into the compressor 31 again.

(3-2) Cooling Operation During the cooling operation, the four-way switching valve 32 is switched to the second state (the state indicated by the broken line in FIG. 1).

  In the main refrigerant circuit 81, the low-pressure gas refrigerant in the refrigeration cycle is sucked into the compressor 31 and is compressed until it reaches a high pressure in the refrigeration cycle, and then discharged. The high-pressure gas refrigerant discharged from the compressor 31 is sent to the outdoor heat exchanger 33 through the discharge pipe 38 and the four-way switching valve 32. The high-pressure gas refrigerant sent to the outdoor heat exchanger 33 exchanges heat with the outside air supplied as a cooling source by the outdoor fan 34 in the outdoor heat exchanger 33, dissipates heat, and becomes high-pressure liquid refrigerant. The high-pressure liquid refrigerant that has radiated heat in the outdoor heat exchanger 33 is sent to the main valve 35. The high-pressure liquid refrigerant sent to the main valve 35 is depressurized by the main valve 35 to a low pressure in the refrigeration cycle. The low-pressure liquid refrigerant decompressed by the main valve 35 is sent to the indoor heat exchanger 21. The low-pressure refrigerant sent to the indoor heat exchanger 21 exchanges heat with indoor air supplied as a heating source by the indoor fan 22 in the indoor heat exchanger 21 and evaporates. As a result, the room air is cooled and then supplied to the room to cool the room. The low-pressure gas refrigerant evaporated in the indoor heat exchanger 21 is sent to the suction pipe 37 through the four-way switching valve 32 and is sucked into the compressor 31 again.

(4) Operation at the time of forward cycle defrosting operation of the air conditioner Next, the operation at the time of forward cycle defrosting operation of the air conditioner 100 executed by the control unit 40 will be described. As described above, the normal cycle defrosting operation is an operation performed when it is determined that frost formation has occurred in the outdoor heat exchanger 33 during the heating operation.

  In the normal cycle defrosting operation, the air conditioner 100 is operated while the four-way switching valve 32 is in the first state (the state indicated by the solid line in FIG. 1) as in the heating operation. In the normal cycle defrosting operation, the refrigerant flows in the main refrigerant circuit 81 in the same manner as in the heating operation. Therefore, it is possible to perform the defrosting while continuing the heating.

  In the normal cycle defrosting operation, the compressor motor 31m is operated at a predetermined rotational speed, preferably the maximum rotational speed. In this way, by operating the compressor motor 31m of the compressor 31 at the highest possible rotational speed, it is easy to keep the input power to the compressor 31 large and to secure the amount of heat for defrosting. Further, during the forward cycle defrosting operation, the indoor fan 22 is continuously operated to continue the heating operation.

  Further, the superheat valve 52 is opened during the positive cycle defrosting operation. When the overheat valve 52 is opened, the high-temperature and high-pressure gas refrigerant discharged from the compressor 31 is supplied to the suction pipe 37. Thereby, the refrigerant cooled by performing defrosting in the outdoor heat exchanger 33 and the refrigerant supplied through the overheat valve 52 are mixed in the suction pipe 37, thereby preventing liquid back of the compressor 31. Thus, the compressor 31 can be continuously operated. In the present embodiment, in the positive cycle defrosting operation, the main valve 35 is controlled so that the temperature of the refrigerant flowing through the indoor heat exchanger 21 detected by the indoor heat exchanger temperature sensor 61 becomes the target temperature value. The superheat valve 52 is controlled so that the superheat degree of the discharged refrigerant detected by the discharge temperature sensor 64 becomes a target discharge superheat degree (for example, 10 deg).

  Further, during the forward cycle defrosting operation, the outdoor fan 34 is controlled by the control unit 40 as follows.

  FIG. 6 is a flowchart showing an example of a specific control operation of the outdoor fan 34 by the control unit 40. As described above, during the heating operation, the outdoor fan 34 performs a normal rotation operation.

  First, in step S1, it is determined whether or not the operation of the air conditioner 100 is switched from the heating operation to the normal cycle defrosting operation. That is, in step S1, it is determined whether or not frost formation has occurred in the outdoor heat exchanger 33 during the heating operation. And when a determination result is NO (namely, when heating operation is continued), it returns to step S1. When the determination result is YES (that is, when switching to the normal cycle defrosting operation), the process proceeds to step S2.

  In step S2, the control unit 40 controls the fan motor 34m so that the forward rotation operation of the outdoor fan 34 is stopped. Thereby, outside air is taken in in the casing 30a, and the air flow discharged outside the casing 30a through the outdoor heat exchanger 33 does not occur. Then, the process proceeds to step S3.

  In step S3, the control unit 40 determines whether or not the temperature of the heat sink 71 detected by the heat sink temperature sensor 66 is equal to or higher than a predetermined value (for example, a value corresponding to 60 degrees). When the determination result is NO (that is, when the temperature of the heat sink 71 is less than a predetermined value), the process returns to step S3. When the determination result is YES (that is, when the temperature of the heat sink 71 is equal to or higher than a predetermined value), the process proceeds to step S4.

  In step S4, the control unit 40 starts execution of reverse rotation control during defrosting. Specifically, the control unit 40 controls the fan motor 34m so that the outdoor fan 34 starts reverse rotation operation. As a result, an air flow that circulates in the casing 30a is generated. Then, the process proceeds to step S5.

  In step S5, it is determined whether or not the operation of the air conditioner 100 is switched from the normal cycle defrosting operation to the heating operation. In other words, whether or not the normal cycle defrosting operation is terminated and the heating operation is restored. Determined. That is, in step S5, it is determined whether or not frost removal in the outdoor heat exchanger 33 has been completed. When the determination result is NO (that is, when the defrosting is not completed), the process returns to step S5. When the determination result is YES (that is, when the defrosting is completed), the process proceeds to step S6.

  In step S6, the control unit 40 ends the execution of the reverse rotation control during defrosting and controls the fan motor 34m so that the outdoor fan 34 performs the forward rotation operation. That is, the control unit 40 controls the fan motor 34m so that the operation of the outdoor fan 34 is switched from the reverse rotation operation to the normal rotation operation. Thereby, outside air is taken in in the casing 30a, and the air flow discharged | emitted out of the casing 30a through the outdoor heat exchanger 33 arises. At this time, the air conditioning apparatus 100 starts the heating operation. That is, the control unit 40 closes the overheat valve 52, controls the operations of the compressor 31, the indoor fan 22, and the outdoor fan 34 so that the indoor temperature becomes the target temperature (set temperature), and discharge temperature sensor 64. The opening degree of the main valve 35 is adjusted based on the refrigerant temperature on the discharge side of the compressor 31 detected by the above.

(5) Features (5-1)
In the present embodiment, since the reverse rotation control at the time of defrosting is executed during the normal cycle defrosting operation, it becomes difficult for the outside air to pass through the outdoor heat exchanger 33, and therefore, between the refrigerant flowing through the outdoor heat exchanger 33 and the outside air. Thus, heat exchange can be suppressed. For this reason, it can be prevented that the time until the temperature of the outdoor heat exchanger 33 reaches the defrosting operation end temperature becomes long. Moreover, since the air in the casing 30a is agitated by performing reverse rotation control during defrosting during the forward cycle defrosting operation, the circulating heat can be applied to the heat sink 71 to cool the heat sink 71. For this reason, the heat generated by the electrical component can be released to the outside.

  As a result, the temperature rise of the electrical component can be suppressed, and the possibility of extending the execution time of the normal cycle defrosting operation can be reduced.

(5-2)
In the present embodiment, when the temperature of the heat sink 71 becomes equal to or higher than a predetermined value during the forward cycle defrosting operation, reverse rotation control during defrosting is executed. For this reason, compared with the case where reverse rotation control at the time of a defrost is always performed during normal cycle defrost operation, the power consumption amount can be suppressed.

(6) Modification (6-1)
In the above embodiment, an electric valve is employed as the main valve 35 and the overheat valve 52, but an electromagnetic valve may be employed as the main valve 35 and the overheat valve 52.

(6-2)
In the defrosting operation of the above embodiment, the refrigerant circulates in the main refrigerant circuit 81 in the same direction as in the heating operation, that is, the compressor 31, the indoor heat exchanger 21, the main valve 35, and the outdoor heat exchanger 33 in this order. This is a so-called forward cycle defrosting operation in which the refrigerant circulates.

  Instead, in the defrosting operation, the refrigerant circulates in the main refrigerant circuit 81 in the same direction as in the cooling operation, that is, the compressor 31, the outdoor heat exchanger 33, the main valve 35, and the indoor heat exchanger 21. A so-called reverse cycle defrosting operation in which the refrigerant circulates in order may be used. Moreover, the air-conditioning apparatus which can perform both a normal cycle defrost operation and a reverse cycle defrost operation as a defrost operation may be sufficient.

(6-3)
In the above embodiment, in the forward cycle defrosting operation, when it is determined that the temperature of the heat sink 71 detected by the heat sink temperature sensor 66 is equal to or higher than a predetermined value, the reverse rotation control during defrosting is started, and the forward cycle defrosting is performed. The control is continued until the operation is finished.

  Instead of this, the reverse rotation control during defrosting may be ended after the reverse rotation control during defrosting is started and before the normal cycle defrosting operation is ended. For example, the state in which the temperature of the heat sink 71 detected by the heat sink temperature sensor 66 is lower than a predetermined value after the start of reverse rotation control during defrosting and before the end of the normal cycle defrosting operation is longer than a predetermined time. When continuing, the reverse rotation control at the time of defrosting may be complete | finished.

  INDUSTRIAL APPLICABILITY The present invention can suppress an increase in temperature of an electrical component and reduce the possibility that the execution time of the defrosting operation is extended, and is effectively applied to an air conditioner that performs the defrosting operation.

30a casing 33 outdoor heat exchanger 34 outdoor fan 70 electrical component box 71 heat sink 100 air conditioner

JP 2009-287843 A

Claims (2)

In an air conditioner that performs normal operation and defrosting operation,
A casing (30a);
An outdoor heat exchanger (33) disposed in the casing;
An outdoor fan (34) disposed in the casing and rotating so as to take in air from outside the casing and pass it through the outdoor heat exchanger during the normal operation;
An electrical component that is disposed in the casing, houses electrical components for controlling devices including the outdoor fan, and is provided with a heat sink (71) for escaping the heat generated by the electrical components to the outside. A box (70);
With
During the defrosting operation, the outdoor fan is rotated opposite to the normal operation so as to suppress air from passing through the outdoor heat exchanger and to stir the air in the casing during the defrosting operation. Reverse rotation control,
Air conditioner (100). When the temperature of the heat sink detected by the heat sink temperature sensor provided on the heat sink is equal to or higher than a predetermined value, the reverse rotation control during defrosting is performed.
The air conditioning apparatus according to claim 1.

Images