JPWO2019003306A1 - Air conditioner - Google Patents

Abstract

An air conditioner according to the present invention includes a compressor that compresses a refrigerant, a condenser that condenses the refrigerant by heat exchange, a throttle device that decompresses the refrigerant that is condensed, and a refrigerant that is depressurized by heat exchange with air. A refrigeration cycle device that constitutes a refrigerant circuit that connects an evaporator that evaporates the air with a pipe, and that circulates a refrigerant; A control device that performs control related to the refrigeration cycle device, wherein the control device is set in advance to a drive frequency at which the compressor is currently driven in an oil return operation of returning the refrigerating machine oil in the refrigerant circuit to the compressor. When it is determined that the frequency obtained by adding the first set frequency is lower than the stay preventing frequency for preventing the stay of the refrigerating machine oil in the refrigerant circuit, the frequency obtained by adding the first set frequency to the drive frequency currently being driven is used. The first driving time to drive the compressor, by repeating the determination until retention prevention frequency, performs control to increase the driving frequency.

Description

  The present invention relates to an air conditioner. In particular, it relates to processing and control in oil return operation.

  Conventionally, an air conditioner equipped with a refrigerant circuit uses a compressor with a variable operating capacity such as an inverter to cope with fluctuations in the air conditioning load, and a drive frequency output to the compressor according to the magnitude of the air conditioning load. Is controlled. By the way, during low-load operation in which the drive frequency of the compressor is set low, the amount of circulating refrigerant in the refrigerant circuit decreases, so that the refrigerating machine oil discharged from the compressor accompanying the refrigerant easily accumulates in the refrigerant circuit. Become. As a result, the amount of refrigerating machine oil in the compressor may decrease, and the compressor may overheat and seizure may occur.

  Therefore, when the low-capacity operation of the compressor continues for a long time, the compressor is forcibly operated at a high capacity to perform an oil return operation for increasing the refrigerant circulation amount. There is known a refrigerator in which refrigeration oil accumulated in a refrigerant circuit is returned to a compressor.

  Further, while the refrigerant circulation amount is being increased, the valve opening of the refrigerant flow control valve is increased to ensure a sufficient flow of the refrigerant flowing through the indoor heat exchanger. Further, there is known one that promotes the recovery of refrigerating machine oil (for example, see Patent Document 1).

JP-A-2002-349938

  In the conventional air conditioner, during the oil return operation, the drive frequency of the compressor is determined regardless of the air conditioning load. For this reason, the blowing temperature decreases.

  Here, an electric heater is installed in the air conditioner or in a duct connected to the outlet of the air conditioner, and the air conditioner can be set to keep the temperature and humidity of the air in the air-conditioned space constant. (Referred to as a constant temperature / humidity air conditioner). In the constant temperature / humidity air conditioner, keeping the temperature of the air in the air-conditioned space constant and keeping the circulating air volume constant is given priority over energy saving.

  In general, in a constant-temperature and constant-humidity air conditioner, the refrigeration cycle device in the air conditioner cools the air and heats it with an electric heater to keep the temperature of the air in the air-conditioned space constant. Is performed. In the case of a constant temperature and humidity air conditioner, where the outside air temperature is low and the air conditioner easily exerts cooling capacity, or when the amount of heat to be processed by the air conditioner is small due to intrusion of outside air, heat radiation, etc. In some cases, the operating frequency of the compressor became low, and the oil return operation was periodically performed.

  When the oil return operation is performed, the compressor frequency increases regardless of the air conditioning load, so that the blowout temperature decreases until the electric heater follows, and the temperature of the air in the air conditioning target space decreases. There were challenges. In particular, in factories, inspection rooms, test rooms, and the like where temperature control is strict, there has been a demand to avoid fluctuations in the temperature of the air in the space to be air-conditioned even during the oil return operation.

  The present invention has been made to solve the above-described problems, and has as its object to obtain an air conditioner that can stabilize air sent to a space to be air-conditioned during an oil return operation.

  The air-conditioning apparatus according to the present invention relates to a compressor that compresses a refrigerant, a condenser that condenses the refrigerant by heat exchange, a throttle device that depressurizes the refrigerant related to condensation, and a heat exchange between the air and a decompressor. A refrigeration cycle device that forms a refrigerant circuit that circulates the refrigerant by connecting an evaporator that evaporates the refrigerant with a pipe, and a heating device that adjusts and heats the air that has passed through the evaporator based on the temperature of the air. And a control device that performs control related to the refrigeration cycle device, wherein the control device determines in advance the drive frequency at which the compressor is currently driving in the oil return operation of returning the refrigeration oil in the refrigerant circuit to the compressor. When it is determined that the frequency obtained by adding the first set frequency obtained is lower than the stay prevention frequency for preventing the stay of the refrigerating machine oil in the refrigerant circuit, the frequency obtained by adding the first set frequency to the drive frequency currently being driven. In the first operating time, to drive the compressor, by repeating the determination until retention prevention frequency, performs control to increase the driving frequency.

  According to the air conditioner of the present invention, the control device performs control to gradually increase the drive frequency of the compressor to the stagnation prevention frequency. The heating based on the temperature of the air can be followed. For this reason, the temperature of the air sent from the air conditioner to the space to be air-conditioned can be stabilized.

FIG. 2 is a diagram illustrating an outline of a configuration of the air-conditioning apparatus according to Embodiment 1 of the present invention. FIG. 2 is a diagram illustrating a configuration of an outdoor unit controller 115 according to Embodiment 1 of the present invention. FIG. 4 is a diagram illustrating a processing procedure related to an oil return operation of the air-conditioning apparatus according to Embodiment 1 of the present invention. It is a figure explaining a processing procedure concerning an oil return operation of an air conditioner concerning Embodiment 2 of this invention. It is a figure explaining a processing procedure concerning an oil return operation of an air conditioner concerning Embodiment 3 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, in the following drawings, components denoted by the same reference numerals are the same or equivalent, and are common to the entire text of the embodiments described below. In addition, the forms of the constituent elements shown in the entire text of the specification are merely examples, and the present invention is not limited to these descriptions. In particular, the combination of components is not limited to only the combination in each embodiment, and the components described in other embodiments can be appropriately applied to another embodiment. The level of the temperature, the pressure, and the like is not determined in relation to an absolute value, but is determined relatively in a state or operation of the device.

Embodiment 1 FIG.
FIG. 1 is a diagram showing an outline of a configuration of an air conditioner according to Embodiment 1 of the present invention. It is assumed that the air conditioner of Embodiment 1 is an air conditioner for constant temperature and humidity. The air conditioner according to Embodiment 1 includes a refrigeration cycle device 100 and a heating device 200. In the first embodiment, refrigeration cycle apparatus 100 cools air. The heating device 200 heats the air from the refrigeration cycle device 100. The air conditioner sends air whose temperature and humidity have been adjusted by the refrigeration cycle device 100 and the heating device 200 to a space to be air-conditioned. Here, the air conditioning target space in the following description is, for example, a space corresponding to a living room, a laboratory, an operating room, a manufacturing site, an examination room, a building, a warehouse, and the like.

<Description of configuration>
As shown in FIG. 1, the refrigeration cycle apparatus 100 according to Embodiment 1 has an outdoor unit 110 and an indoor unit 120. The outdoor unit 110 and the indoor unit 120 are connected by an indoor / outdoor communication liquid pipe 130 and an indoor / outdoor communication gas pipe 140.

  The outdoor unit 110 includes a compressor 111, an oil separator 112, an outdoor blower 114, an outdoor heat exchanger 113, and an outdoor unit controller 115. The compressor 111 compresses and discharges the sucked refrigerant. Here, the compressor 111 is provided with an inverter device or the like, and by arbitrarily changing the rotation speed based on the drive frequency F, the capacity of the compressor 111 (the amount of refrigerant to be sent out per unit time) can be finely changed. it can. The oil separator 112 separates the refrigerating machine oil discharged together with the gaseous refrigerant (gas refrigerant) discharged from the compressor 111 from the gas refrigerant. The refrigerating machine oil separated in the oil separator 112 is returned to the compressor 111 after passing through a capillary tube (not shown) connected to the compressor 111. The oil separator 112 can return most of the refrigerating machine oil discharged from the compressor 111 to the compressor 111.

  The outdoor heat exchanger 113 is a heat exchanger serving as a condenser. The outdoor heat exchanger 113 exchanges heat between the refrigerant discharged from the compressor 111 and the outdoor air to condense and liquefy the refrigerant. The outdoor blower 114 is installed corresponding to the outdoor heat exchanger 113. The outdoor blower 114 allows outdoor air to pass through the outdoor heat exchanger 113 in order to efficiently exchange heat between the refrigerant and the outdoor air. For the outdoor blower 114, for example, the drive frequency of the fan motor may be arbitrarily changed by an inverter device to finely change the rotation speed of a propeller or the like. The outdoor unit controller 115 controls devices included in the outdoor unit 110 and the like. Here, in particular, control relating to the compressor 111 is performed. The configuration of the outdoor unit controller 115 will be described later.

  The indoor unit 120 includes an indoor blower 123, an indoor heat exchanger 122, an expansion valve 121, an indoor unit controller 124, and a suction temperature sensor 125. The expansion valve 121 serving as the expansion device is a valve that decompresses and expands the refrigerant. As a device other than the expansion valve 121 for reducing the pressure of the refrigerant, for example, there is a capillary tube (capillary tube). The indoor heat exchanger 122 is a heat exchanger serving as an evaporator. The indoor heat exchanger 122 exchanges heat between the refrigerant that has passed through the expansion valve 121 and the outdoor air, and evaporates and vaporizes the refrigerant. The indoor blower 123 is installed corresponding to the indoor heat exchanger 122. The indoor blower 123 allows the air to pass through the indoor heat exchanger 122 in order to efficiently exchange heat between the air and the refrigerant. For the indoor blower 123, for example, the drive frequency of the fan motor may be arbitrarily changed by an inverter device to finely change the rotation speed of a propeller or the like. The indoor unit controller 124 controls devices included in the indoor unit 120. The suction temperature sensor 125 detects the temperature of the air flowing into the indoor unit 120 and sent to the indoor heat exchanger 122, and sends a signal related to the detection to the indoor unit controller 124.

  The heating device 200 has an electric heater 201 and an electric heater controller 202. The electric heater 201 heats the air that has passed through the indoor heat exchanger 122. Here, in Embodiment 1, it is assumed that electric heater 201 is installed in indoor unit 120 of refrigeration cycle apparatus 100. The electric heater 201 is controlled by the electric heater controller 202. The electric heater controller 202 controls the heating of the air by the electric heater 201 so that the air in the air-conditioned space has the set temperature and the set humidity. Here, the electric heater 201 may be installed inside a duct attached to the outlet of the indoor unit 120. Further, the electric heater controller 202 may be installed inside the indoor unit 120. Further, it may be integrated with the indoor unit controller 124.

<Operation of air conditioner>
Next, the operation of the air-conditioning apparatus according to Embodiment 1 will be described. Here, the flow of the refrigerating machine oil during the cooling operation in the refrigerant circuit of the air-conditioning apparatus of Embodiment 1 will be described. The compressor 111 compresses and discharges the refrigerant. At this time, the refrigerating machine oil is discharged together with the refrigerant. Most of the refrigerating machine oil discharged together with the refrigerant from the compressor 111 is collected by an oil separator 112 provided near the pipe on the discharge side of the compressor 111. The refrigerating machine oil collected in the oil separator 112 is returned to the compressor 111 through a path different from the main refrigerant circuit.

  The refrigerating machine oil not collected in the oil separator 112 flows through the indoor / outdoor communication liquid pipe 130 and flows into the indoor unit 120. Here, when the driving frequency F of the compressor 111 is high and the circulation amount of the refrigerant circulating in the refrigerant circuit is large, the refrigerating machine oil passes through the indoor unit 120, flows through the indoor / outdoor communication gas pipe 140, and Return without any trouble. On the other hand, when the drive frequency F of the compressor 111 is low and the circulation amount of the refrigerant in the refrigerant circuit is small, the conveying force for the refrigerating machine oil is small. Therefore, the refrigerating machine oil tends to stay in the indoor / outdoor communication gas pipe 140 and the indoor heat exchanger 122.

  FIG. 2 is a diagram illustrating a configuration of outdoor unit controller 115 according to Embodiment 1 of the present invention. As shown in FIG. 2, the outdoor unit controller 115 according to the first embodiment includes a control device 300, a storage device 310, and a timing device 320. The control device 300 includes a comparison determination unit 301, a calculation unit 302, and a control unit 303. In the first embodiment, the comparison determination unit 301 makes a determination by performing a comparison based on a plurality of data. The calculation unit 302 performs a calculation process. In particular, in the first embodiment, an operation relating to the drive frequency F of the compressor 111 is performed. The control unit 303 controls devices included in the outdoor unit 110. In particular, a process related to the oil return operation is executed to control the drive frequency F of the compressor 111.

  The storage device 310 is a device that stores data related to the processing of the control device 300. Here, the recording regarding the driving frequency F of the compressor 111 is performed. The timer 320 has a timer and the like, and measures elapsed time and the like.

  Here, in the first embodiment, it is assumed that control device 300 of outdoor unit controller 115 is configured by a microcomputer having, for example, a CPU (Central Processing Unit). Further, the storage device 310 stores data in which processing procedures related to control and the like are programmed. The control device 300 implements control by executing the processing of each unit based on the data of the program stored in the storage device 310. However, the present invention is not limited to such a configuration, and each unit of the control device 300 may be configured by a different dedicated device (hardware) to realize each function.

  FIG. 3 is a diagram illustrating a processing procedure related to the oil return operation of the air-conditioning apparatus according to Embodiment 1 of the present invention. Next, processing and control related to the oil return operation will be described. Here, the description will be made on the assumption that the outdoor unit controller 115 performs processing and control relating to the oil return operation as the entire device.

  When the normal operation, which is the operation for air conditioning the space to be air-conditioned, is performed, for example, periodically, the outdoor unit controller 115 determines whether or not the condition of the oil return operation is satisfied, as shown in step S101. I do. If it is determined that the condition is not satisfied, the process proceeds to step S108, and the normal operation is continued, and the process ends.

  Here, in step S101, it is determined whether or not the oil return operation is necessary, but the determination condition is not particularly limited. In general, the condition is that the operation at the drive frequency F of the compressor 111 is continued for a certain time or more such that the flow rate of the refrigerant in the indoor / outdoor communication gas pipe 140 is equal to or less than a certain speed. can do. Here, based on the temperature of the refrigerant sucked into the compressor 111, the low-pressure side pressure, and the like, the frequency serving as the threshold for determination and the operation time may be corrected.

  If it is determined in step S101 that the condition is satisfied, the oil return operation is started. When the oil return operation is started, in step S102, the outdoor unit controller 115 records the start frequency Fstart which is the drive frequency F at the start of the oil return operation, and proceeds to step S103. In step S103, it is determined whether the constant temperature / humidity setting has been made. If it is determined that the constant temperature / humidity setting has been made, the process proceeds to step S104. If it is determined that the constant temperature / humidity setting has not been made, the process proceeds to step S108.

  In step S104, the current drive frequency Fnow, which is the drive frequency F currently being driven by the compressor 111, is recorded, and the process proceeds to step S105. In step S105, the frequency of the sum of the current driving frequency Fnow and the maximum frequency change amount ΔFmax is compared with the staying prevention frequency Fr. Here, the maximum frequency change amount ΔFmax is a first set frequency that is set in advance in consideration of the influence on the blowout temperature, and is the maximum frequency that can be increased at one time. The first set frequency is, for example, a frequency at which the variation of the blowing temperature becomes less than 0.5 ° C., and a frequency of about 1 to 5 Hz is set. The first set frequency can be an arbitrary frequency as long as it does not exceed the maximum frequency change amount ΔFmax. Further, the stagnation prevention frequency Fr is a frequency necessary for driving the compressor 111 for preventing stagnation of the refrigerating machine oil in the refrigerant circuit in the oil return operation. The stagnation prevention frequency Fr is determined, for example, so that the refrigerant flow rate in the indoor / outdoor communication gas pipe 140 is equal to or higher than a certain speed, and a frequency of about several tens Hz is set.

  If it is determined that the sum of the current drive frequency Fnow and the maximum frequency change amount ΔFmax is smaller than the stagnation prevention frequency Fr, the process proceeds to step S106. If it is determined that the sum of the current drive frequency Fnow and the maximum frequency change amount ΔFmax is equal to or higher than the stagnation prevention frequency Fr, the process proceeds to step S108.

  In step S106, an instruction is issued to drive the driving frequency F of the compressor 111 as the sum of the current driving frequency Fnow and the maximum frequency change amount ΔFmax, and the process proceeds to step S107. In step S107, the operation is continued during the first operation time t1, and the process proceeds to step S104. Then, the comparison processing with the retention prevention frequency Fr is repeated until the drive frequency F of the compressor 111 becomes the retention prevention frequency Fr.

  Here, the first operation time t1 is a time set as a time until the output of the electric heater 201 increases and the blowout temperature returns to the set temperature. The first operation time t1 may be set based on the control logic of the electric heater 201, the allowable temperature fluctuation of the space to be air-conditioned, and the like in relation to the maximum frequency change amount ΔFmax. Further, the user, the worker, and the like may set the outdoor unit controller 115.

  On the other hand, when it is determined in step S103 that the constant temperature / humidity setting is not performed, or when it is determined in step S105 that the sum of the current drive frequency Fnow and the maximum frequency change ΔFmax is equal to or higher than the stagnation prevention frequency Fr, The process proceeds to step S108. In step S108, the compressor 111 is instructed to drive the driving frequency F at Fr, and the process proceeds to step S109.

  In step S109, the operation related to oil return is continued during the second operation time t2, and the process proceeds to S110. In step S110, the operation shifts to the normal operation. Here, the second operation time t2 is a time set in consideration of a time until the refrigerating machine oil returns to the outdoor unit 110. The second operation time t2 may be set based on the length and diameter of the heat transfer tube of the indoor heat exchanger 122, the length and diameter of the indoor / outdoor communication gas pipe 140, and the like.

  As described above, according to the air-conditioning apparatus of Embodiment 1, in the oil return operation, the drive frequency F of the compressor 111 is increased in a stepwise manner without suddenly decreasing the blowout temperature. Therefore, the heating by the electric heater 201 can be followed. Therefore, the temperature of the air sent from the air conditioner to the space to be air-conditioned can be kept substantially constant, particularly when the temperature and humidity are set. Therefore, the temperature of the air in the space to be air-conditioned is stabilized, and stable operation of the manufacturing apparatus in the space to be air-conditioned and improvement in product quality can be achieved.

Embodiment 2 FIG.
In the first embodiment, the processing and control in the oil return operation of the air conditioner have been described. Here, the drive frequency F of the compressor 111 after performing the oil return operation is higher than the air-conditioning load of the space to be air-conditioned, and is not balanced with the air-conditioning load. For this reason, the output of the electric heater 201 is also unnecessarily large. In order to save energy, the drive frequency F of the compressor 111 may be returned to a frequency that balances the air conditioning load of the air-conditioned space when the oil return operation is completed. However, when the drive frequency F of the compressor 111 is largely changed, the temperature changes greatly. Therefore, in the air-conditioning apparatus according to Embodiment 2, when shifting to the normal operation, the drive frequency F of the compressor 111 is reduced by the maximum frequency change amount ΔFmax which is the second set frequency. Here, the second set frequency can be any frequency as long as it does not exceed the maximum frequency change amount ΔFmax.

  FIG. 4 is a diagram illustrating a processing procedure related to an oil return operation of the air-conditioning apparatus according to Embodiment 2 of the present invention. Next, an operation of the air-conditioning apparatus according to Embodiment 2 will be described. Here, also in the second embodiment, the description will be given on the assumption that the outdoor unit controller 115 controls the oil return operation. In FIG. 4, those having the same step numbers perform the same operations as those described in the first embodiment.

  In the second embodiment, as shown in FIG. 4, after the second operation time t2 operation is continued in step S109, in step S109A, the driving frequency F obtained by subtracting the maximum frequency change ΔFmax from the stagnation prevention frequency Fr in step S109A. Is instructed to drive the compressor 111. Then, in step S109B, the drive frequency F is compared with the start frequency Fstart. If it is determined that the drive frequency F and the start frequency Fstart match, the process proceeds to step S110. If it is determined that the drive frequency F does not match the start frequency Fstart, the flow shifts to step S109C. In step S109C, it is determined whether or not the difference between the drive frequency F and the start frequency Fstart is larger than the maximum frequency change amount ΔFmax. If it is determined that the difference between the drive frequency F and the start frequency Fstart is equal to or less than the maximum frequency change amount ΔFmax, the process proceeds to step S109D with the drive frequency F set as the start frequency Fstart. If it is determined that the difference between the drive frequency F and the start frequency Fstart is larger than the maximum frequency change amount ΔFmax, the drive frequency F is reduced by the maximum frequency change amount ΔFmax to obtain a new drive frequency F in step S109E. Then, the determination in step S109B is performed again. In step S110, the compressor 111 shifts to the normal operation at the drive frequency F based on the instruction.

  As described above, according to the air-conditioning apparatus of Embodiment 2, the outdoor unit controller 115 reduces the stagnation prevention frequency Fr by the maximum frequency change amount ΔFmax in the normal operation after performing the oil return operation. An instruction to drive the compressor 111 is issued at the drive frequency F. Therefore, the cooling of the air by the refrigerant circuit and the heating of the air by the electric heater 201 can be performed according to the air conditioning load in the air conditioning target space. Therefore, energy can be saved. In addition, since the drive frequency F is not reduced at once, but is reduced by the maximum frequency change amount ΔFmax from the retention prevention frequency Fr, a rapid change in temperature can be suppressed. The temperature of the sending air can be kept constant.

Embodiment 3 FIG.
FIG. 5 is a diagram illustrating a processing procedure related to an oil return operation of the air-conditioning apparatus according to Embodiment 3 of the present invention. Next, an operation of the air-conditioning apparatus according to Embodiment 3 will be described. Here, also in the third embodiment, the description will be given on the assumption that the outdoor unit controller 115 performs control relating to the oil return operation. In FIG. 5, those having the same step numbers perform the same operations as those described in the first embodiment.

  In the third embodiment, an operation transition period t3 is provided between the time when the condition for performing the oil return operation is satisfied and the time when the oil return operation is performed. At this time, at the point of the pre-signal output time t4 shorter than the operation transition period t3, a pre-signal is output to the electric heater controller 202 as a pre-notification signal for notifying the oil return operation in advance. By transmitting the advance signal, a delay in following the electric heater 201 is prevented.

  If it is determined in step S101 that the condition for performing the oil return operation is satisfied, it is further determined in step S101A whether the advance signal output time t4 has elapsed. If it is determined in step S101A that the advance signal output time t4 has elapsed, in step S101B, an advance signal is output to the electric heater controller 202 so that the electric heater 201 adjusts the output before starting the oil return operation. To

  Then, in step S101C, it is further determined whether or not the set time A has elapsed. If it is determined that the set time A has elapsed, the process proceeds to step S102. Here, the set time A is a time obtained by subtracting the prior signal output time t4 from the operation transition period t3. In step S102, the oil return operation is started, and the start frequency Fstart is recorded.

  As described above, according to the air-conditioning apparatus of Embodiment 3, when it is determined that the oil return operation is to be performed, the advance signal output time t4 within the operation transition period t3 is transmitted to the electric heater controller 202 in advance. Therefore, the output of the electric heater 201 can be adjusted before performing the oil return operation. For this reason, the temperature of the air blown from the indoor unit 120 to the space to be air-conditioned can be kept substantially constant. Therefore, the temperature of the space to be air-conditioned is stabilized, and stable operation of the manufacturing apparatus and improvement of product quality can be achieved.

  Here, it is known in advance that the oil return operation ends when the second operation time t2 elapses after the compressor 111 is driven at the stagnation prevention frequency Fr. Therefore, the electric heater controller 202 can control the electric heater 201 without a prior signal. However, a prior signal may be sent to the electric heater controller 202 in the same manner as when starting the oil return operation.

Embodiment 4 FIG.
In the above-described first to third embodiments, the outdoor unit controller 115 has the control device 300 and the like, and performs processing related to the oil return operation. However, the present invention is not limited to this. For example, the indoor unit controller 124 may perform control or the like. Further, the control may be performed by an external control device.

  Further, in the above-described embodiment, the processing and control in the constant-temperature and constant-humidity air conditioner have been described, but the present invention is not limited to this. For example, in a case where a certain target space is cooled or heated by a plurality of air conditioners, when one air conditioner performs an oil return operation, another air conditioner performs capacity control of the compressor. Thus, the temperature of the target space can be kept constant. For this reason, it can be applied also to a normal refrigeration cycle device.

  DESCRIPTION OF SYMBOLS 100 Refrigeration cycle apparatus, 110 outdoor unit, 111 compressor, 112 oil separator, 113 outdoor heat exchanger, 114 outdoor blower, 115 outdoor unit controller, 120 indoor unit, 121 expansion valve, 122 indoor heat exchanger 123 indoor blower, 124 indoor unit controller, 125 suction temperature sensor, 130 indoor / outdoor communication liquid pipe, 140 indoor / outdoor communication gas pipe, 200 heating device, 201 electric heater, 202 electric heater controller, 300 control device, 301 Comparison / determination unit, 302 calculation unit, 303 control unit, 310 storage device, 320 clock device.

Claims (4)

A compressor that compresses the refrigerant, a condenser that condenses the refrigerant by heat exchange, a throttle device that decompresses the refrigerant according to condensation, and an evaporator that evaporates the refrigerant according to the decompression by heat exchange with air. A refrigeration cycle device that connects a vessel with a pipe to constitute a refrigerant circuit that circulates the refrigerant,
A heating device that performs heating by adjusting the air that has passed through the evaporator based on the temperature of the air,
A control device that performs control related to the refrigeration cycle device,
The control device includes:
In an oil return operation of returning the refrigerating machine oil in the refrigerant circuit to the compressor, a frequency obtained by adding a first predetermined frequency to a driving frequency currently being driven by the compressor is the frequency of the refrigerating machine oil. When it is determined that it is lower than the stagnation prevention frequency for preventing stagnation in the refrigerant circuit, at a frequency obtained by adding the first set frequency to the drive frequency that is currently being driven, the first operation time, the compressor is driven, An air conditioner that repeats the determination and performs the control to increase the drive frequency up to the stagnation prevention frequency.   2. The air conditioner according to claim 1, wherein the control device performs the control in a normal operation when a constant temperature and constant humidity setting for maintaining a set temperature and a set humidity in the space to be air-conditioned is performed.   When the control device drives the compressor at the stagnation prevention frequency for a second operation time, the control device drives the compressor at a frequency obtained by subtracting a second predetermined frequency from the stagnation prevention frequency. The air-conditioning apparatus according to claim 1, wherein control is performed to shift to normal operation.   The control device, when determining that the oil return operation is to be performed, sends a signal to the heating device in advance, and thereafter, after a predetermined set time has elapsed, starts the oil return operation. The air conditioner according to any one of claims 1 to 3.

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