JP2018048752A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner capable of reducing cold air feeling a user feels in heating operation.SOLUTION: A CPU is configured to reduce a room temperature Ti from a condensation temperature Tc to calculate a temperature difference ΔT, and determine whether the calculated temperature difference ΔT is smaller than a threshold temperature difference Tth. When the temperature difference ΔT is smaller than the threshold temperature difference Tth, the CPU makes a rotational frequency of a compressor larger than a current rotational frequency to increase discharge pressure Ph, that is, the condensation temperature Tc, so that the temperature difference ΔT becomes the threshold temperature difference Tth or more. On the other hand, when the temperature difference ΔT is equal to or more than the threshold temperature difference Tth, the CPU determines the rotational frequency of the compressor according to requirement capacity Ar.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner that can improve comfort during heating operation.

  When performing heating operation with an air conditioner, the temperature of the indoor heat exchanger that functions as a condenser is low immediately after the start of heating operation. In this state, if the indoor fan speed is increased to increase the air volume, it will take time to increase the temperature of the indoor heat exchanger and the rise time of the heating operation will be longer, and cold air will be blown out from the indoor unit. Feel a cold wind.

  In order to solve the above problems, for example, in Patent Document 1, at the start of heating operation, the indoor heat exchanger is warmed without driving the indoor fan, and then the indoor fan is driven at a low rotation speed to blow out the air. Air conditioning that detects the temperature and, if the detected blowing temperature reaches a predetermined temperature, can drive the rotation speed of the indoor fan at an arbitrarily set rotation speed (for example, the rotation speed according to the air volume set by the user) A machine has been proposed.

  In the air conditioner described in Patent Document 1, as described above, the rotation speed of the indoor fan is kept low or the indoor fan is not driven until the blowing temperature reaches a predetermined temperature after the heating operation is started. Therefore, the indoor heat exchanger warms up quickly after starting the heating operation. Moreover, since it can prevent that a cold wind blows off from an indoor unit when heating operation is started, it does not give a user a feeling of cold wind.

JP-A-60-120135

  Generally, when the air conditioner performs a heating operation, the rotation speed of the compressor is set according to a temperature difference between a set temperature required by the user and a room temperature. Specifically, the greater the temperature difference between the set temperature and the room temperature, the greater the capacity required for the indoor unit to bring the room temperature to the set temperature, so the rotational speed of the compressor is increased. According to this, since the temperature difference between the set temperature and the room temperature is large at the start of the heating operation, the rotational speed of the compressor becomes high. On the other hand, as the time elapses from the start of the heating operation and the temperature difference between the set temperature and the room temperature decreases, the necessary capacity gradually decreases, and accordingly, the rotational speed of the compressor also gradually decreases. And the higher the capability mentioned above, that is, the higher the rotation speed of the compressor, the higher the condensation temperature in the indoor heat exchanger and the higher the outlet temperature of the indoor unit.

  In recent years, an air conditioner has been proposed in which the indoor temperature can be finely detected by an indoor unit (for example, in units of 0.25 ° C.). In such an air conditioner, since the temperature difference between the set temperature and the room temperature can be calculated in detail, the necessary capacity corresponding to the temperature difference between the set temperature and the room temperature can be finely adjusted. As a result, when the room temperature is approaching the set temperature, the indoor unit exhibits more capability than necessary, and the room temperature is set to the set temperature while preventing the indoor unit from shutting off because the room temperature exceeds the set temperature. Can be reached. However, as the temperature difference between the room temperature and the set temperature decreases, the capacity required for the indoor unit decreases and the condensation temperature in the indoor heat exchanger also decreases, so the blowout temperature decreases and the user feels cold. There was a fear.

  The present invention solves the above-described problems, and an object thereof is to provide an air conditioner that can reduce a feeling of cool air given to a user during heating operation.

  In order to solve the above problems, an air conditioner of the present invention includes an outdoor unit having a compressor, an indoor heat exchanger, an indoor fan, an indoor unit having a room temperature detecting means for detecting room temperature, and an indoor heat exchanger. Condensing temperature detecting means for detecting the condensing temperature in the indoor heat exchanger when it functions as a condenser, the condensing temperature detected by the condensing temperature detecting means and the room temperature detected by the room temperature detecting means are taken in and the driving of the compressor is controlled. It has a control means. The control means takes in the condensation temperature detected by the condensation temperature detection means and takes in the room temperature detected by the room temperature detection means during the heating operation, and obtains the temperature difference between the acquired condensation temperature and the room temperature. When the obtained temperature difference is smaller than the predetermined threshold temperature difference, the control means increases the rotation speed of the compressor to increase the condensation temperature to a temperature at which the temperature difference becomes equal to or greater than the threshold temperature difference.

  According to the air conditioner of the present invention configured as described above, by increasing the rotation speed of the compressor and increasing the condensation temperature so that the temperature difference between the condensation temperature and room temperature is equal to or greater than a predetermined threshold temperature difference. A decrease in the blowing temperature can be suppressed. Thereby, the cool wind feeling given to a user at the time of heating operation can be reduced.

It is explanatory drawing of the air conditioner in embodiment of this invention, (A) is a refrigerant circuit figure, (B) is a block diagram of an outdoor unit control means. It is a flowchart which shows the flow of the process in the outdoor unit control means in embodiment of this invention.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. As an embodiment, an air conditioner in which one outdoor unit and one indoor unit are connected by two refrigerant pipes will be described as an example. The present invention is not limited to the following embodiments, and can be variously modified without departing from the gist of the present invention.

  As shown in FIG. 1A, an air conditioner 1 according to this embodiment includes an outdoor unit 2 installed outdoors, and an indoor unit installed indoors and connected to the outdoor unit 2 with a liquid pipe 4 and a gas pipe 5. Machine 3 is provided. Specifically, the liquid pipe 4 has one end connected to the closing valve 25 of the outdoor unit 2 and the other end connected to the liquid pipe connecting portion 33 of the indoor unit 3. The gas pipe 5 has one end connected to the closing valve 26 of the outdoor unit 2 and the other end connected to the gas pipe connecting portion 34 of the indoor unit 3. The refrigerant circuit 10 of the air conditioner 1 is configured as described above.

  First, the outdoor unit 2 will be described. The outdoor unit 2 is connected to a compressor 21, a four-way valve 22, an outdoor heat exchanger 23, an outdoor fan 24, a closing valve 25 to which one end of the liquid pipe 4 is connected, and one end of the gas pipe 5. A closing valve 26 and an expansion valve 27 are provided. And these each apparatus except the outdoor fan 24 is mutually connected by each refrigerant | coolant piping explained in full detail below, and the outdoor unit refrigerant circuit 10a which makes a part of the refrigerant circuit 10 is comprised.

  The compressor 21 is a variable capacity compressor capable of changing the operating capacity by controlling the rotation speed by an inverter (not shown). The refrigerant discharge side of the compressor 21 is connected to the port a of the four-way valve 22 by a discharge pipe 61. The refrigerant suction side of the compressor 21 is connected to the port c of the four-way valve 22 by a suction pipe 66.

  The four-way valve 22 is a valve for switching the direction in which the refrigerant flows, and includes four ports a, b, c, and d. The port a is connected to the refrigerant discharge side of the compressor 21 by the discharge pipe 61 as described above. The port b is connected to one refrigerant inlet / outlet of the outdoor heat exchanger 23 by a refrigerant pipe 62. The port c is connected to the refrigerant suction side of the compressor 21 by the suction pipe 66 as described above. The port d is connected to the shutoff valve 26 and the outdoor unit gas pipe 64.

  The outdoor heat exchanger 23 exchanges heat between the refrigerant and the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 24 described later. As described above, one refrigerant inlet / outlet of the outdoor heat exchanger 23 is connected to the port b of the four-way valve 22 by the refrigerant pipe 62, and the other refrigerant inlet / outlet is connected to the closing valve 25 by the outdoor unit liquid pipe 63.

  The expansion valve 27 is an electronic expansion valve, for example. The expansion valve 27 adjusts the amount of refrigerant flowing into the outdoor heat exchanger 23 or the amount of refrigerant flowing out of the outdoor heat exchanger 23 by adjusting the opening degree thereof.

  The outdoor fan 24 is formed of a resin material and is disposed in the vicinity of the outdoor heat exchanger 23. The outdoor fan 24 is rotated by a fan motor (not shown) to take outside air into the outdoor unit 2 from a suction port (not shown) of the outdoor unit 2, and the outdoor air exchanged heat with the refrigerant in the outdoor heat exchanger 23. It discharges from the blower outlet which is not illustrated to the exterior of the outdoor unit 2.

  In addition to the configuration described above, the outdoor unit 2 is provided with various sensors. As shown in FIG. 1A, the discharge pipe 61 includes a discharge pressure sensor 71 which is a condensation temperature detecting means for detecting the pressure of the refrigerant discharged from the compressor 21, and the refrigerant discharged from the compressor 21. A discharge temperature sensor 73 for detecting the temperature is provided. The suction pipe 66 is provided with a suction pressure sensor 72 that detects the pressure of the refrigerant sucked into the compressor 21 and a suction temperature sensor 74 that detects the temperature of the refrigerant sucked into the compressor 21.

  Between the outdoor heat exchanger 23 and the expansion valve 27 in the outdoor unit liquid pipe 63, a heat exchange temperature sensor for detecting the temperature of the refrigerant flowing out of the outdoor heat exchanger 23 or flowing into the outdoor heat exchanger 23. 75 is provided. An outdoor air temperature sensor 76 that detects the temperature of the outside air flowing into the outdoor unit 2, that is, the outside air temperature, is provided near the suction port (not shown) of the outdoor unit 2.

  The outdoor unit 2 includes an outdoor unit control means 200. The outdoor unit control means 200 is mounted on a control board stored in an electrical component box (not shown) of the outdoor unit 2. As shown in FIG. 1B, the outdoor unit control means 200 includes a CPU 210, a storage unit 220, a communication unit 230, and a sensor input unit 240.

  The storage unit 220 includes a ROM and a RAM, and stores a control program for the outdoor unit 2, detection values corresponding to detection signals from various sensors, control states of the compressor 21 and the outdoor fan 24, and the like. Although not shown, the storage unit 220 stores in advance a rotation speed table that determines the rotation speed of the compressor 21 in accordance with a requested capability received from the indoor unit 3 described later. The communication unit 230 is an interface that performs communication with the indoor unit 3. The sensor input unit 240 captures detection results from various sensors of the outdoor unit 2 and outputs them to the CPU 210.

  CPU210 takes in the detection result in each sensor of outdoor unit 2 mentioned above via sensor input part 240. FIG. Further, the CPU 210 takes in a control signal transmitted from the indoor unit 3 via the communication unit 230. The CPU 210 controls the driving of the compressor 21 and the outdoor fan 24 based on the detection results and control signals taken in. In addition, the CPU 210 performs switching control of the four-way valve 22 based on the detection results and control signals taken in. Furthermore, the CPU 210 adjusts the opening degree of the outdoor expansion valve 27 based on the acquired detection result and control signal.

  Next, the indoor unit 3 will be described with reference to FIG. The indoor unit 3 includes an indoor heat exchanger 31, an indoor fan 32, a liquid pipe connection portion 33 to which the other end of the liquid pipe 4 is connected, and a gas pipe connection portion 34 to which the other end of the gas pipe 5 is connected. I have. And these each apparatus except the indoor fan 32 is mutually connected by each refrigerant | coolant piping explained in full detail below, and the indoor unit refrigerant circuit 10b which makes a part of refrigerant circuit 10 is comprised.

The indoor heat exchanger 31 exchanges heat between indoor air taken into the indoor unit 3 from a suction port (not shown) of the indoor unit 3 by rotation of the refrigerant and an indoor fan 32 described later. An indoor unit liquid pipe 67 is connected to the liquid pipe connection part 33, and the other refrigerant inlet / outlet is connected to the gas pipe connection part 34 via an indoor unit gas pipe 68. The indoor heat exchanger 31 functions as an evaporator when the indoor unit 3 performs a cooling operation, and functions as a condenser when the indoor unit 3 performs a heating operation.
In addition, in the liquid pipe connection part 33 and the gas pipe connection part 34, each refrigerant | coolant piping is connected by welding, a flare nut, etc.

  The indoor fan 32 is formed of a resin material and is disposed in the vicinity of the indoor heat exchanger 31. The indoor fan 31 is rotated by a fan motor (not shown) so that indoor air is taken into the indoor unit 3 from a suction port (not shown) of the indoor unit 3, and the indoor air heat-exchanged with the refrigerant in the indoor heat exchanger 31 is taken into the room. It blows out into the room from the blower outlet which machine 3 does not illustrate.

  In addition to the configuration described above, the indoor unit 3 is provided with various sensors. The indoor unit liquid pipe 67 is provided with a liquid side temperature sensor 77 that detects the temperature of the refrigerant flowing into or out of the indoor heat exchanger 31. The indoor unit gas pipe 68 is provided with a gas side temperature sensor 78 that detects the temperature of the refrigerant flowing out of the indoor heat exchanger 31 or flowing into the indoor heat exchanger 31. A room temperature sensor 79 that is a room temperature detecting means for detecting the temperature of room air flowing into the indoor unit 3, that is, the room temperature, is provided in the vicinity of a suction port (not shown) of the indoor unit 3.

  Moreover, although illustration and detailed description are abbreviate | omitted, the indoor unit 3 is provided with the indoor unit control means. The indoor unit control means includes a CPU, a storage unit, a communication unit, and a sensor input unit. The storage unit includes a ROM and a RAM, and stores a control program for the indoor unit 3, detection values corresponding to detection signals from various sensors, a control state of the indoor fan 32, and the like. The communication unit is an interface for performing communication with the outdoor unit control means 200 of the outdoor unit 2. The sensor input unit captures detection results from various sensors of the indoor unit 3 and outputs them to the CPU. The CPU takes in the detection result of each sensor of the indoor unit 3 described above via the sensor input unit. Further, the CPU takes in a signal related to control transmitted from the outdoor unit 2 via the communication unit. In addition, the CPU performs drive control of the indoor fan 32 based on the acquired detection result and control signal.

  Further, the CPU calculates a temperature difference between the set temperature set by the user by operating a remote controller (not shown) and the room temperature detected by the room temperature sensor 79, and transmits the required capacity based on the calculated temperature difference to the communication unit. To the outdoor unit control means 200 of the outdoor unit 2.

  Next, the flow of the refrigerant and the operation of each part in the refrigerant circuit 10 during the air conditioning operation of the air conditioner 1 in the present embodiment will be described with reference to FIG. In the following description, the case where the indoor unit 3 performs the heating operation will be described, and the detailed description will be omitted for the case where the cooling / dehumidifying operation is performed. Moreover, the arrow in FIG. 1 (A) has shown the flow of the refrigerant | coolant at the time of heating operation.

  When the indoor unit 3 performs the heating operation, the CPU 210 performs a state where the four-way valve 22 is indicated by a solid line as shown in FIG. 1A, that is, the port a and the port d of the four-way valve 22 communicate with each other. Switch so that port b and port c communicate. As a result, the refrigerant circulates in the direction indicated by the solid line arrow in the refrigerant circuit 10, and the outdoor heat exchanger 23 functions as an evaporator and the indoor heat exchanger 31 functions as a condenser.

  The high-pressure refrigerant discharged from the compressor 21 flows through the discharge pipe 61 and flows into the four-way valve 22, flows from the four-way valve 22 through the outdoor unit gas pipe 64, and flows into the gas pipe 5 through the closing valve 26. The refrigerant flowing through the gas pipe 5 flows into the indoor unit 3 through the gas pipe connection part 34.

  The refrigerant that has flowed into the indoor unit 3 flows through the indoor unit gas pipe 68 and flows into the indoor heat exchanger 31, and is condensed by exchanging heat with the indoor air taken into the indoor unit 3 by the rotation of the indoor fan 32. To do. As described above, the indoor heat exchanger 31 functions as a condenser, and the indoor air that has exchanged heat with the refrigerant in the indoor heat exchanger 31 is blown into the room from a blower outlet (not shown), so that the indoor unit 3 is installed. The heated room is heated.

  The refrigerant flowing out of the indoor heat exchanger 31 flows through the indoor unit liquid pipe 67 and flows into the liquid pipe 4 through the liquid pipe connecting portion 33. The refrigerant flowing through the liquid pipe 4 and flowing into the outdoor unit 2 through the closing valve 25 is decompressed when flowing through the outdoor unit liquid pipe 63 and passing through the expansion valve 27.

  The refrigerant flowing through the expansion valve 27 and flowing into the outdoor heat exchanger 23 evaporates by exchanging heat with the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 24. The refrigerant that has flowed out of the outdoor heat exchanger 23 into the refrigerant pipe 62 flows through the four-way valve 22 and the suction pipe 66, is sucked into the compressor 21, and is compressed again.

  When the indoor unit 3 performs a cooling operation, the CPU 210 performs the state where the four-way valve 22 is indicated by a broken line as shown in FIG. 1A, that is, the port a and the port b of the four-way valve 22 communicate with each other. Further, the port c and the port d are switched so as to communicate with each other. Thereby, the refrigerant circuit 10 becomes a cooling cycle in which the outdoor heat exchanger 23 functions as a condenser and the indoor heat exchanger 31 functions as an evaporator.

  Next, processing related to the rotational speed control of the compressor 21 when the air conditioner 1 is performing the heating operation will be described with reference to FIG. FIG. 2 shows the flow of processing performed by the CPU 210 of the outdoor unit control means 200 when the air conditioner 1 performs the heating operation. In FIG. 2, ST represents a process step, and the number following this represents a step number. In FIG. 2, the processing related to the present invention is mainly described. Other processing such as control of the air conditioner 1 such as control related to the pressure and temperature of the refrigerant circuit 10 mainly performed by the outdoor unit 2 is generally described. Description of processing related to general control is omitted.

  In the following description, the discharge pressure detected by the discharge pressure sensor 71 is Ph, the high-pressure saturation temperature obtained using the discharge pressure Ph, that is, the condensation temperature in the indoor heat exchanger 31 that functions as a condenser during heating operation is Tc, The room temperature of the room in which the indoor unit 3 is detected detected by the room temperature sensor 79 is Ti, the temperature difference obtained by subtracting the room temperature Ti from the condensation temperature Tc is ΔT, the threshold temperature difference that is the threshold value of the temperature difference ΔT is Tth, and the indoor unit 2 is The required capacity, which is the capacity required for the outdoor unit 3, is assumed to be Ar.

  Here, the threshold temperature difference Tth is obtained by performing a test or the like in advance and stored in the storage unit 220, and is, for example, 10 ° C. This threshold temperature difference Tth decreases in the capacity required for the indoor unit 2 and the rotational speed of the compressor 21 decreases. Along with this, the condensation temperature Tc decreases, and the temperature difference ΔT is greater than the threshold temperature difference Tth. When it becomes small, it is a value that it is known that the user feels a cool wind feeling by the air blown out from the indoor unit 2 at the blowout temperature according to the condensation temperature Tc at this time. The threshold temperature difference Tth may be changed by the user within a predetermined range, for example, a range of ± 1 ° C., according to his / her preference. Further, since the feeling of cold wind felt by the user varies depending on the air volume blown from the indoor unit 3 even at the same blowing temperature, the threshold temperature difference Tth varies depending on the air volume. For example, the threshold temperature when the air volume is high When the difference Tth is 11 ° C., the air volume: medium, the threshold temperature difference Tth may be 10 ° C., and when the air volume: weak, the threshold temperature difference Tth may be 9 ° C.

  The required capacity Ar is determined based on the temperature difference between the set temperature and the room temperature Ti. Specifically, a table in which the required capacity Ar is determined according to the temperature difference between the set temperature and the room temperature Ti is stored in advance in the storage unit of the indoor unit 3, and the control unit of the indoor unit 3 refers to this table. The required capacity Ar corresponding to the obtained temperature difference is extracted. The required capacity Ar increases as the temperature difference between the set temperature and the room temperature Ti increases.

  If there is an air conditioning operation start instruction by the user, CPU 210 determines whether or not the user's operation instruction is a heating operation instruction (ST1). If it is not a heating operation instruction (ST1-No), the CPU 210 executes a cooling / dehumidifying operation start process that is a start process of a cooling operation or a dehumidifying operation (ST13). Here, the cooling / dehumidifying operation start process is a process performed when the CPU 210 operates the four-way valve 22 to set the refrigerant circuit 100 to the cooling cycle, and when the cooling operation or the dehumidifying operation is first performed.

  Then, the CPU 210 starts the compressor 21 and the outdoor fan 24 at a predetermined number of revolutions, and instructs the indoor unit 3 to perform drive control of the indoor fan 32 via the communication unit 230 to perform a cooling operation or a dehumidifying operation. Is started (ST14), and the process proceeds to ST10.

  If it is a heating operation instruction in ST1 (ST1-Yes), the CPU 210 executes a heating operation start process (ST2). Here, the heating operation start process is a state in which the CPU 210 operates the four-way valve 22 to bring the refrigerant circuit 100 into the state shown in FIG. 1A, that is, the refrigerant circuit 100 is set to the heating cycle. It is a process performed when performing.

  Next, the CPU 210 starts the heating operation control (ST3). At the start of the heating operation control, the CPU 210 activates the compressor 21 at a rotational speed corresponding to the required capacity Ar from the indoor unit 3 and activates the outdoor fan 24 at a predetermined rotational speed. Further, the CPU 210 takes in the discharge temperature of the compressor 21 detected by the discharge temperature sensor 73 via the sensor input unit 240 and adjusts the opening degree of the expansion valve 27 according to the taken-in discharge temperature. Further, the CPU 210 transmits an operation start signal indicating that the heating operation is started to the indoor unit 3 via the communication unit 230. The CPU of the indoor unit control means of the indoor unit 3 that has received the operation start signal via the communication unit activates the indoor fan 32 at the number of rotations according to the air volume instruction from the user.

  Next, the CPU 210 takes in the discharge pressure Ph detected by the discharge pressure sensor 71 through the sensor input unit 240 and also takes in the room temperature Ti from the indoor unit 3 through the communication unit 230 (ST4). The room temperature Ti is obtained by the CPU of the indoor unit 3 taking in the value detected by the room temperature sensor 79 via the sensor input unit and transmitting it to the outdoor unit 2 via the communication unit. Each detection value described above is captured by the CPU 210 and stored in the storage unit 220 every predetermined time (for example, every 30 seconds).

  Next, CPU210 calculates | requires condensation temperature Tc using the discharge pressure Ph taken in by ST4 (ST5). Moreover, CPU210 takes in the required capability Ar which the indoor unit 3 transmits via the communication part 230 (ST6). The requested capacity Ar is transmitted from the indoor unit 3 every time the temperature difference between the set temperature and the room temperature Ti changes in the indoor unit 3, and the CPU 210 overwrites and saves the latest requested capacity Ar that has been captured.

  Next, the CPU 210 calculates the temperature difference ΔT by subtracting the room temperature Ti acquired in ST4 from the condensation temperature Tc determined in ST5, and determines whether or not the calculated temperature difference ΔT is smaller than the threshold temperature difference Tth (ST7). ).

  When the temperature difference ΔT is smaller than the threshold temperature difference Tth (ST7-Yes), the CPU 210 sets the number of rotations of the compressor 21 as the number of rotations at which the temperature difference ΔT is equal to or greater than the threshold temperature difference Tth (ST8). Proceed. As described above, when the temperature difference ΔT is smaller than the threshold temperature difference Tth, the blowout temperature of the indoor unit 3 is low, and the user may feel a cold wind. Therefore, the CPU 210 sets the rotation speed of the compressor 21 to be higher than the current rotation speed and increases the discharge pressure Ph, that is, the condensation temperature Tc, so that the temperature difference ΔT becomes equal to or greater than the threshold temperature difference Tth. .

  On the other hand, when the temperature difference ΔT is greater than or equal to the threshold temperature difference Tth in ST7 (ST7-No), the CPU 210 sets the number of rotations of the compressor 21 in accordance with the required capacity Ar captured in ST7 (ST9) and processes in ST10. To proceed. As described above, the storage unit 220 stores in advance a rotation speed table that determines the rotation speed of the compressor 21 in accordance with the required capacity Ar of the indoor unit 3. The CPU 210 refers to the rotation speed table, extracts the rotation speed corresponding to the fetched required capacity Ar, and controls the compressor 21 so as to obtain the extracted rotation speed.

  After completing the process of ST8 or ST9, CPU 210 determines whether or not there is an operation mode switching instruction from the user (ST10). Here, the operation mode switching instruction is an instruction to switch from the current operation (here, heating operation) to another operation (cooling operation or dehumidifying operation). When there is an operation mode switching instruction (ST10-Yes), the CPU 210 returns the process to ST1. When there is no operation mode switching instruction (ST10-No), the CPU 210 determines whether or not there is an operation stop instruction by the user (ST11). Here, the operation stop instruction indicates that the indoor unit 3 stops the operation.

  If there is an operation stop instruction (ST11-Yes), the CPU 210 executes an operation stop process (ST12) and ends the process. In the operation stop process, the CPU 210 stops the compressor 21 and the outdoor fan 24 and fully closes the expansion valve 27. In addition, the CPU 210 transmits an operation stop signal indicating that the operation is stopped to the indoor unit 3 via the communication unit 230. The CPU of the indoor unit 3 that has received the operation stop signal via the communication unit stops the indoor fan 32.

  If there is no operation stop instruction in ST11 (ST11-No), CPU 210 determines whether or not the current operation is a heating operation (ST15). If the current operation is the heating operation (ST15-Yes), the CPU 210 returns the process to ST4. If the current operation is not the heating operation (ST15-No), that is, if the current operation is the cooling operation or the dehumidifying operation, the CPU 210 returns the process to ST14.

  As described above, in the air conditioner 1 of the present invention, when the temperature difference ΔT obtained by subtracting the room temperature Ti from the condensation temperature Tc during the heating operation is smaller than the threshold temperature difference Tth, the temperature difference ΔT is the threshold value. The rotational speed of the compressor 21 is controlled in order to increase the condensation temperature Tc so as to be equal to or higher than the temperature difference Tth. As a result, even when the room temperature Ti approaches the set temperature and the required capacity Ar from the indoor unit 3 becomes small, and the rotational speed of the compressor 21 is reduced accordingly, the rotational speed of the compressor 21 is reduced by the temperature difference. Since ΔT is not lowered below the rotational speed corresponding to the condensation temperature Tc that is smaller than the threshold temperature difference Tth, it is possible to prevent the temperature from the indoor unit 3 from being lower than the temperature at which the user feels a cold wind. Therefore, it is possible to reduce the feeling of cold wind given to the user during the heating operation.

  In the embodiment described above, the case where the condensation temperature detecting means is the discharge pressure sensor 71 and the condensation temperature in the indoor heat exchanger 31 is obtained using the discharge pressure Pd detected by the discharge pressure sensor 71 has been described. However, the present invention is not limited to this, and the condensing temperature detecting means is a refrigerant temperature sensor disposed in the middle part of the path of the indoor heat exchanger 31, and the condensing temperature may be directly detected by the refrigerant temperature sensor.

DESCRIPTION OF SYMBOLS 1 Air conditioner 2 Outdoor unit 3 Indoor unit 10 Refrigerant circuit 21 Compressor 22 Four-way valve 23 Outdoor heat exchanger 31 Indoor heat exchanger 71 Discharge pressure sensor 79 Room temperature sensor 200 Outdoor unit control means 210 CPU
220 Storage Ar Required Capacity Ph Discharge Pressure Tc Condensation Temperature Ti Room Temperature ΔT Temperature Difference Tth Threshold Temperature Difference

Claims (2)

An outdoor unit having a compressor;
An indoor heat exchanger, an indoor fan, and an indoor unit having room temperature detecting means for detecting room temperature,
Condensation temperature detection means for detecting the condensation temperature in the indoor heat exchanger when the indoor heat exchanger functions as a condenser;
Control means for taking in the condensation temperature detected by the condensation temperature detection means and the room temperature detected by the room temperature detection means, and controlling the drive of the compressor;
An air conditioner having
When the control means is performing a heating operation,
Taking in the condensation temperature detected by the condensation temperature detection means and taking in the room temperature detected by the room temperature detection means, obtaining the temperature difference between the taken-in condensation temperature and the room temperature,
When the temperature difference is smaller than a predetermined threshold temperature difference, the rotation temperature of the compressor is increased to increase the condensation temperature to a temperature at which the temperature difference is equal to or greater than the threshold temperature difference.
An air conditioner characterized by that. Increase or decrease the threshold temperature difference within a predetermined range according to the amount of air blown from the indoor unit,
The air conditioner according to claim 1.

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