JP2019027613A - Air conditioner - Google Patents

Abstract

To provide an air conditioner capable of rapidly reactivating a compressor after the compressor is stopped.SOLUTION: When stopping operating an air conditioner 1, a CPU 210 calculates a temperature difference ΔT by subtracting an outdoor heat exchange temperature Th from an outside air temperature To. If the temperature difference ΔT is equal to or greater than 1°C, cooling operation mode: outdoor fan rotation speed Cf=0 rpm or a heating operation mode: outdoor fan rotation speed Cf=800 rpm is extracted. If the temperature difference ΔT is less than -1°C, the CPU 210 extracts a cooling operation mode: outdoor fan rotation speed Cf=800 rpm or a heating operation mode: outdoor fan rotation speed Cf=0 rpm. If the temperature difference ΔT is -1°C or greater and less than 1°C, the CPU 210 extracts an outdoor fan rotation speed Cf=400 rpm. The CPU 210 then stops a compressor 21 after driving or stopping an outdoor fan 24 at the extracted outdoor fan rotation speed Cf.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an air conditioner, and more particularly to control of an outdoor fan.

  When the air conditioner is performing cooling operation or heating operation, when the operation is stopped by the user's instruction, the room temperature falls below the set temperature during the cooling operation, or the room temperature is set temperature during the heating operation In the case of the so-called thermo-off state in which the operation is temporarily stopped as described above, the compressor that has been driven so far is stopped.

  Immediately after the compressor is stopped, the pressure difference between the pressure on the high pressure side (refrigerant discharge side) and the pressure on the low pressure side (refrigerant suction side) of the compressor is usually large. In this way, when the compressor is restarted, for example, when the operation is started according to a user's instruction while the pressure difference remains large, due to a large load caused by the pressure difference between the high pressure side and the low pressure side of the compressor. It may not be possible to restart. Therefore, in order to restart the compressor, the pressure difference between the pressure on the high pressure side and the pressure on the low pressure side of the compressor needs to be small.

  The pressure difference between the high-pressure side pressure and the low-pressure side pressure immediately after the compressor is stopped becomes smaller as time passes after the compressor is stopped. Specifically, when the outdoor heat exchanger functions as a condenser in the cooling operation, the heat release of the refrigerant in the outdoor heat exchanger proceeds according to the elapsed time from the stop of the compressor, and Thus, the condensing pressure, that is, the pressure on the high pressure side of the compressor is reduced. On the other hand, when the outdoor heat exchanger functions as an evaporator in heating operation, the heat absorption of the refrigerant of the outdoor heat exchanger proceeds according to the elapsed time from the stop of the compressor, and the evaporation pressure according to the heat absorption of the refrigerant That is, the pressure on the low pressure side of the compressor increases.

  In other words, after the compressor is stopped during the cooling operation, the refrigerant naturally radiates heat in the outdoor heat exchanger, so it may take time for the pressure on the high pressure side of the compressor to decrease. Further, after the compressor is stopped during the heating operation, the refrigerant naturally absorbs heat in the outdoor heat exchanger, so it may take time for the pressure on the low pressure side of the compressor to rise. That is, it takes time for the pressure difference between the pressure on the high-pressure side and the pressure on the low-pressure side to drop to a value that does not hinder the restart of the compressor (for example, 0.3 MPa). There is a problem that cannot be restarted.

  Patent Document 1 proposes to drive an outdoor fan for a predetermined time after the compressor is stopped as an air conditioner that solves the above-described problem. By driving the outdoor fan, the refrigerant of the outdoor heat exchanger that functions as a condenser in the cooling operation is cooled earlier than when the outdoor fan is stopped, and the condensation pressure is reduced, that is, the pressure on the high pressure side is reduced. Since the pressure decreases quickly, the pressure difference between the pressure on the high pressure side and the pressure on the low pressure side quickly decreases. In the heating operation, the refrigerant of the outdoor heat exchanger that functions as an evaporator is heated faster than when the outdoor fan is stopped, and the evaporation pressure rises, that is, the pressure on the low-pressure side rises faster. The pressure difference between the pressure on the side and the pressure on the low pressure side is quickly reduced. Therefore, the pressure difference between the high-pressure side pressure and the low-pressure side pressure is quickly reduced to a value that does not hinder the restart of the compressor, so that the compressor can be restarted quickly.

JP-A-6-241586

  However, even if the outdoor fan is driven after the compressor is stopped as in the air conditioner described in Patent Document 1, the temperature of the outdoor air temperature and the temperature of the outdoor heat exchanger (hereinafter referred to as the outdoor heat exchange temperature) Depending on the difference, the time required for the pressure difference between the pressure on the high-pressure side and the pressure on the low-pressure side to be reduced to a value that does not hinder the restart of the compressor is not necessarily shorter than when the outdoor fan is not driven. Absent.

  For example, in the cooling operation, when the outdoor air temperature is higher than the outdoor heat exchange temperature, the refrigerant is less likely to be cooled by the outside air sent to the outdoor heat exchanger by driving the outdoor fan, so the higher pressure side than when the outdoor fan is not driven. It takes time to reduce the pressure difference between the pressure at the low pressure side and the pressure at the low pressure side. In the heating operation, when the outdoor air temperature is lower than the outdoor heat exchange temperature, the refrigerant is less likely to be heated by the outdoor air sent to the outdoor heat exchanger by driving the outdoor fan, so that the higher pressure side than when the outdoor fan is not driven. It takes time to reduce the pressure difference between the pressure at the low pressure side and the pressure at the low pressure side. Therefore, even if the outdoor fan is driven after the compressor is stopped, the time until the compressor can be restarted may not be shortened as compared with the case where the outdoor fan is not driven after the compressor is stopped.

  The present invention solves the above-described problems, and an object thereof is to provide an air conditioner that can restart the compressor at an early stage after the compressor is stopped.

  In order to solve the above-described problems, an air conditioner of the present invention includes an outdoor air temperature detector, an outdoor heat exchanger, an outdoor fan, an outdoor fan, an outdoor air temperature detecting means for detecting an outdoor air temperature, and an outdoor heat exchanger. It has an outdoor unit having an outdoor heat exchange temperature detecting means for detecting a heat exchange temperature, an indoor unit having an indoor heat exchanger, and a control means for controlling driving of the compressor and the outdoor fan. And when the control means stops the compressor, the temperature difference obtained by subtracting the outdoor heat exchange temperature detected by the outdoor heat exchange temperature detection means from the operation mode at the time of stopping the air conditioning operation and the outside air temperature detected by the outside air temperature detection means. The drive control of the outdoor fan is performed at the rotation speed based on the above.

  According to the air conditioner of the present invention configured as described above, the outdoor fan after the compressor is stopped is controlled so that the rotation speed is based on the temperature difference obtained by subtracting the outdoor heat exchange temperature from the operation mode and the outdoor air temperature. To do. Thereby, the compressor can be restarted early after the compressor is stopped without being influenced by the outside air temperature more than the conventional air conditioner.

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 fan rotation speed table in the embodiment of the present invention. 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 an outdoor unit and an 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. Thus, the refrigerant circuit 10 of the air conditioner 1 is formed.
<Configuration of outdoor unit>

  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 refrigerant circuit 10 is formed.

  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 outdoor heat exchanger 23 functions as a condenser during cooling operation and functions as an evaporator during heating operation by switching a four-way valve 22 described later.

  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 high pressure detection means for detecting the pressure of the refrigerant discharged from the compressor 21 (corresponding to the pressure on the high pressure side of the present invention). A discharge temperature sensor 73 for detecting the temperature of the refrigerant discharged from the compressor 21 is provided. The suction pipe 66 includes a suction pressure sensor 72 which is a low pressure detecting means for detecting the pressure of the refrigerant sucked into the compressor 21 (corresponding to the pressure on the low pressure side of the present invention), and the refrigerant sucked into the compressor 21. An intake temperature sensor 74 for detecting the temperature is provided.

  A heat exchange temperature sensor which is an outdoor heat exchange temperature detecting means for detecting the temperature of the outdoor heat exchanger 23 (hereinafter referred to as the outdoor heat exchange temperature) is provided at a substantially intermediate portion of a refrigerant path (not shown) of the outdoor heat exchanger 23. 75 is provided. An outdoor air temperature sensor 76 that is an outdoor air temperature detecting means for detecting the temperature of the outdoor air flowing into the outdoor unit 2, that is, the outdoor air temperature, is provided in the vicinity of a 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. Further, the CPU 210 performs switching control of the four-way valve 22 based on the detected result and control signal 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.
<Configuration of indoor unit>

  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 formed.

  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 a 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 for detecting the temperature of the room air flowing into the indoor unit 3, that is, the room temperature, is provided near the suction port (not shown) of the indoor unit 3.
<Operation of refrigerant circuit>

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 first, and then the case where the cooling operation is performed will be described.
<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 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 flows through the outdoor unit liquid pipe 63 and passes through the expansion valve 27 having an opening corresponding to the heating capacity required by the indoor unit 3. When the pressure is reduced.

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.
<Cooling operation>

  When the indoor unit 3 performs a cooling operation or a defrosting operation, the CPU 210 communicates the state where the four-way valve 22 is indicated by a broken line, that is, the port a and the port b of the four-way valve 22 as shown in FIG. In addition, the switching is performed so that the port c and the port d communicate with each other. As a result, the refrigerant circulates in the direction indicated by the broken-line arrow in the refrigerant circuit 10, and a cooling cycle in which the outdoor heat exchanger 23 functions as a condenser and the indoor heat exchanger 31 functions as an evaporator is formed.

  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 refrigerant pipe 62, and flows into the outdoor heat exchanger 23. In the case of the cooling operation, the refrigerant flowing into the outdoor heat exchanger 23 is condensed by exchanging heat with the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 24.

  The refrigerant flowing out of the outdoor heat exchanger 23 flows through the outdoor unit liquid pipe 63, and flows out to the liquid pipe 4 through the expansion valve 27 and the closing valve 25 that have an opening degree corresponding to the cooling capacity required by the indoor unit 3. To do. The refrigerant flowing through the liquid pipe 4 and flowing into the indoor unit 3 through the liquid pipe connecting portion 33 flows through the indoor unit liquid pipe 67 and flows into the indoor heat exchanger 31.

  The refrigerant flowing into the indoor heat exchanger 31 evaporates by exchanging heat with the indoor air taken into the interior of the indoor unit 3 by the rotation of the indoor fan 32. Thus, in the case of cooling operation, the indoor heat exchanger 31 functions as an evaporator, 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). The room where the indoor unit 3 is installed is cooled.

  The refrigerant that has flowed out of the indoor heat exchanger 31 flows through the indoor unit gas pipe 68 and flows out to the gas pipe 5 through the gas pipe connecting portion 34. The refrigerant flowing in the gas pipe 5 flows into the outdoor unit 2 through the closing valve 26, flows in the order of the outdoor unit gas pipe 64, the four-way valve 22, and the suction pipe 66, and is sucked into the compressor 21 and compressed again.

When restarting the compressor 21 after stopping the heating operation or the cooling operation described above, the pressure difference between the refrigerant pressure on the refrigerant discharge side and the refrigerant pressure on the refrigerant suction side of the compressor 21 is reduced as soon as possible. This is the object of the present invention, and the specific method will be described below.
<Outdoor fan control after compressor stop>

  Next, the control of the outdoor fan 24 after the compressor 21 is stopped in the air conditioner 1 of the present embodiment will be specifically described mainly with reference to FIGS. 2 and 3.

  When the air conditioner 1 is performing a cooling operation or a heating operation, if the user gives an instruction to stop the operation by a remote control operation (not shown), or if the indoor unit 5 is in a thermo-off state, the compressor 21 is stopped. The thermo-off state is a state in which the room temperature detected by the room temperature sensor 79 of the indoor unit 5 during the cooling operation is lower than the set temperature set by the user by a predetermined temperature (for example, 1 ° C.) or the heating operation. In some cases, the room temperature detected by the room temperature sensor 79 of the indoor unit 5 is higher than a set temperature set by the user by a predetermined temperature (for example, 1 ° C.) or more.

  Immediately after the compressor 21 is stopped, the pressure on the high-pressure side of the refrigerant circuit 10 (specifically, the pressure of the refrigerant existing between the refrigerant discharge side of the compressor 21 and the expansion valve 27. Unit: MPa. High pressure Ph) and the pressure on the low pressure side of the refrigerant circuit 10 (specifically, the pressure of the refrigerant existing between the expansion valve 27 and the refrigerant suction side of the compressor 21. Unit: MPa. The pressure difference (indicated by Pl) (unit: MPa, hereinafter referred to as pressure difference ΔP) is large.

  If the pressure difference ΔP is large when the compressor 21 is restarted after being stopped, the load due to the pressure difference ΔP applied to the compressor 21 is large, and the compressor 21 may not be restarted. Therefore, in order to restart the compressor 21, it waits until the pressure difference ΔP falls below a value that does not hinder the restarting of the compressor 21 (for example, 0.3 Ma, hereinafter referred to as the threshold pressure difference Pth). There is a need.

  In the present embodiment, in order to reduce the time required for the pressure difference ΔP to fall below the threshold pressure difference Pth (hereinafter, sometimes referred to as “equalizing pressure”), when the compressor 21 is stopped, FIG. The drive control of the outdoor fan 24 is performed based on the fan rotation speed table 300 shown in FIG.

  The fan rotation speed table 300 shown in FIG. 2 is based on the operation mode of the air conditioner 1 and the outside air temperature (unit: ° C., hereinafter referred to as the outside air temperature To) when the compressor 21 is stopped. Depending on the temperature difference (unit: ° C., hereinafter referred to as temperature difference ΔT) obtained by subtracting the temperature of the outdoor heat exchanger 23 (unit: ° C., hereinafter referred to as outdoor heat exchange temperature Th), the outdoor fan 24 will be described. The number of rotations (unit: rpm, hereinafter referred to as outdoor fan rotation number Cf) is determined.

  Specifically, first, when the operation mode is “cooling” (meaning cooling operation), the outdoor fan rotation speed Cf when the temperature difference ΔT is 1 ° C. or more is 0 rpm (that is, stopped), and the temperature difference. The outdoor fan rotation speed Cf when ΔT is −1 ° C. or more and less than 1 ° C. is 400 rpm, and the outdoor fan rotation speed Cf when the temperature difference ΔT is less than −1 ° C. is 800 rpm. Of the temperature difference ΔT, −1 ° C. is the first threshold temperature of the present invention, and 1 ° C. is the second threshold temperature of the present invention. Further, the outdoor fan rotation speed Cf: 400 rpm when the temperature difference ΔT is −1 ° C. or more and less than 1 ° C. is set as the cooling reference rotation speed.

  When the air conditioner 1 is performing the cooling operation, as described above, the outdoor heat exchanger 23 functions as a condenser. Therefore, if the condensation pressure in the outdoor heat exchanger 23, that is, the pressure on the high pressure side of the refrigerant circuit 10 can be quickly reduced, the pressure difference ΔP can be quickly reduced to the threshold pressure difference Pth or less.

  Considering the contents described above, in the operation mode of the fan rotation speed table 300; “cooling”, when the temperature difference ΔT is less than −1 ° C., that is, when the outdoor air temperature To is lower than the outdoor heat exchange temperature Th, The outdoor fan 24 is driven at an outdoor fan rotation speed Cf: 800 rpm which is higher than the outdoor fan rotation speed Cf: 400 rpm, which is the reference rotation speed during cooling. As a result, a large amount of outside air at the outside air temperature To passes through the outdoor heat exchanger 23, so that the pressure on the high-pressure side of the refrigerant circuit 10 quickly decreases, and the pressure difference ΔP quickly decreases below the threshold pressure difference Pth.

  On the other hand, when the temperature difference ΔT is 1 ° C. or more, that is, when the outdoor air temperature To is higher than the outdoor heat exchange temperature Th, the outdoor fan rotation speed Cf is set to 0 rpm, that is, the outdoor fan 24 is stopped. When the outdoor fan 24 is driven when the outdoor air temperature To is higher than the outdoor heat exchanger temperature Th, the refrigerant in the outdoor heat exchanger 23 is cooled by the outdoor air having an outdoor air temperature To higher than the outdoor heat exchanger temperature Th passing through the outdoor heat exchanger 23. Since it becomes difficult, it takes time for the pressure on the high-pressure side of the refrigerant circuit 10 to decrease compared to when the outdoor fan 24 is stopped. That is, when the outdoor fan 24 is driven when the outdoor air temperature To is higher than the outdoor heat exchange temperature Th, it takes a longer time for the pressure difference ΔP to fall below the threshold pressure difference Pth than when the outdoor fan 24 is stopped. . Therefore, when the temperature difference ΔT is 1 ° C. or more, the outdoor fan 24 is stopped so that the time until the pressure difference ΔP drops below the threshold pressure difference Pth is not increased.

  When the temperature difference ΔT is not less than −1 ° C. and less than 1 ° C., that is, when the outdoor heat exchange temperature Th and the outdoor air temperature To are substantially the same temperature, the outdoor fan rotation speed Cf that is the reference rotation speed during cooling: The outdoor fan 24 is driven at 400 rpm.

  When the temperature difference ΔT in the fan rotation speed table 300 is −1 ° C. or more and less than 1 ° C., that is, when the outdoor heat exchange temperature Th and the outdoor air temperature To are substantially the same temperature, the temperature difference ΔT is 1 ° C. or more. That is, compared to the case where the outdoor air temperature To is higher than the outdoor heat exchange temperature Th, the outdoor heat exchanger 23 is not difficult to cool, but the temperature difference ΔT is less than −1 ° C. That is, it takes time for the outdoor heat exchanger 23 to be cooled by the outside air at the outside air temperature To as compared with the case where the outside air temperature To is lower than the outdoor heat exchange temperature Th. Therefore, when the temperature difference ΔT is not less than −1 ° C. and less than 1 ° C., the outdoor fan 24 is driven to flow outside air to the outdoor heat exchanger 23, but the rotational speed Cf is less than −1 ° C. The outdoor fan rotational speed Cf at a certain time is set to an outdoor fan rotational speed Cf: 400 rpm which is a reference rotational speed during cooling lower than 800 rpm.

  As described above, the outdoor fan rotation speed Cf during the cooling operation in the fan rotation speed table 300 is set to a lower rotation speed as the temperature difference ΔT increases from the negative temperature toward the positive temperature. If the temperature difference ΔT is 1 ° C. or more, that is, the second threshold temperature or more, the outdoor fan rotation speed Cf is set to 0 rpm. This is due to the following reason.

  As the temperature difference ΔT decreases, that is, as the outdoor air temperature To becomes lower than the outdoor heat exchange temperature Th, the outdoor fan rotation speed Cf is increased, so that a large amount of outdoor air having an outdoor air temperature To lower than the outdoor heat exchange temperature Th is obtained. The pressure difference ΔP can be reduced to the threshold pressure difference Pth or less in a short time by passing it through the outdoor heat exchanger 23.

  On the other hand, as the temperature difference ΔT increases, that is, as the outdoor air temperature To becomes higher than the outdoor heat exchange temperature Th, the outdoor fan rotation speed Cf is decreased, thereby allowing the outdoor air having an outdoor air temperature To higher than the outdoor heat exchange temperature Th to flow. The power consumption of the outdoor fan 24 can be reduced by reducing the outdoor fan rotation speed Cf while preventing the outdoor heat exchanger 23 from passing more than necessary so that the time during which the pressure difference ΔP is equal to or less than the threshold pressure difference Pth does not increase. Can be reduced.

  If the temperature difference ΔT is equal to or greater than the second threshold temperature (1 ° C. in the present embodiment), the outdoor fan rotation speed Cf is set to 0 rpm, so that the outdoor heat exchange is performed by the outdoor air having an outdoor air temperature To higher than the outdoor heat exchange temperature Th. As the chamber 23 is warmed, the outdoor fan 24 is stopped while preventing the time during which the pressure difference ΔP is equal to or less than the threshold pressure difference Pth from becoming longer than when the temperature difference ΔT is less than the second threshold temperature. Thus, the power consumption can be further reduced as compared with the case where the temperature difference ΔT is less than the second threshold temperature.

  Next, when the operation mode is “heating” (meaning heating operation), when the temperature difference ΔT is 1 ° C. or more, the outdoor fan rotation speed Cf is 800 rpm, and the temperature difference ΔT is −1 ° C. or more and less than 1 ° C. The outdoor fan rotation speed Cf is 400 rpm, and the outdoor fan rotation speed Cf when the temperature difference ΔT is less than −1 ° C. is 0 rpm (that is, stopped). Of the temperature difference ΔT, 1 ° C. is the third threshold temperature of the present invention, and −1 ° C. is the fourth threshold temperature of the present invention. Further, the outdoor fan rotation speed Cf: 400 rpm when the temperature difference ΔT is −1 ° C. or more and less than 1 ° C. is set as the heating-time reference rotation speed.

  When the air conditioner 1 is performing the heating operation, the outdoor heat exchanger 23 functions as an evaporator as described above. Therefore, if the evaporation pressure in the outdoor heat exchanger 23, that is, the pressure on the low pressure side of the refrigerant circuit 10 can be quickly increased, the pressure difference ΔP can be quickly decreased to the threshold pressure difference Pth or less.

  Considering the contents described above, in the operation mode of the fan speed table 300; “heating”, when the temperature difference ΔT is 1 ° C. or more, that is, when the outdoor air temperature To is higher than the outdoor heat exchange temperature Th, heating is performed. The outdoor fan 24 is driven at an outdoor fan rotational speed Cf: 800 rpm which is higher than the outdoor fan rotational speed Cf: 400 rpm, which is the reference rotational speed. As a result, a large amount of outside air at the outside air temperature To passes through the outdoor heat exchanger 23, so that the pressure on the low pressure side of the refrigerant circuit 10 quickly rises and the pressure difference ΔP quickly falls below the threshold pressure difference Pth.

  On the other hand, when the temperature difference ΔT is less than −1 ° C., that is, when the outdoor air temperature To is lower than the outdoor heat exchange temperature Th, the outdoor fan rotation speed Cf is set to 0 rpm, that is, the outdoor fan 24 is stopped. . When the outdoor fan 24 is driven when the outdoor air temperature To is lower than the outdoor heat exchange temperature Th, the refrigerant staying in the outdoor heat exchanger 23 is less likely to be warmed by the outdoor air having the low outdoor air temperature To passing through the outdoor heat exchanger 23. Compared with the case where the outdoor fan 24 is stopped, it takes time for the pressure on the low pressure side of the refrigerant circuit 10 to increase. That is, if the outdoor fan 24 is driven when the outdoor air temperature To is lower than the outdoor heat exchange temperature Th, it takes a longer time for the pressure difference ΔP to fall below the threshold pressure difference Pth than when the outdoor fan 24 is stopped. . Therefore, when the temperature difference ΔT is less than −1 ° C., the outdoor fan 24 is stopped so that the time until the pressure difference ΔP drops below the threshold pressure difference Pth is not increased.

  When the temperature difference ΔT is −1 ° C. or more and less than 1 ° C., that is, when the outdoor heat exchange temperature Th and the outdoor air temperature To are substantially the same temperature, the outdoor fan rotation speed Cf that is the reference rotation speed during heating: The outdoor fan 24 is driven at 400 rpm.

  When the temperature difference ΔT in the fan rotation speed table 300 is −1 ° C. or more and less than 1 ° C., that is, when the outdoor heat exchange temperature Th and the outdoor air temperature To are substantially the same temperature, the temperature difference ΔT described above is −1 ° C. However, compared with the case where the outdoor air temperature To is lower than the outdoor heat exchange temperature Th, the outdoor heat exchanger 23 is not easily warmed, but the temperature difference ΔT is 1 ° C. or more. In other words, as compared with a case where the outdoor air temperature To is higher than the outdoor heat exchange temperature Th, it takes time for the outdoor heat exchanger 23 to be warmed by the outdoor air at the outdoor air temperature To. Therefore, when the temperature difference ΔT is −1 ° C. or more and less than 1 ° C., the outdoor fan 24 is driven to flow the outside air to the outdoor heat exchanger 23, but the rotation speed Cf of the temperature difference ΔT is 1 ° C. or more. The outdoor fan rotation speed Cf is 400 rpm, which is a heating reference rotation speed lower than 800 rpm.

  As described above, the outdoor fan rotation speed Cf during the heating operation in the fan rotation speed table 300 is set to a lower rotation speed as the temperature difference ΔT decreases from the positive temperature toward the negative temperature. If the temperature difference ΔT is less than −1 ° C., that is, less than the fourth threshold temperature, the outdoor fan rotation speed Cf is set to 0 rpm. This is due to the following reason.

  As the temperature difference ΔT increases, that is, as the outdoor air temperature To becomes higher than the outdoor heat exchange temperature Th, the outdoor fan rotational speed Cf is increased, so that a large amount of outdoor air with an outdoor air temperature To higher than the outdoor heat exchange temperature Th is obtained. The pressure difference ΔP can be reduced to the threshold pressure difference Pth or less in a short time by passing it through the outdoor heat exchanger 23.

  On the other hand, as the temperature difference ΔT becomes smaller, that is, as the outdoor air temperature To becomes lower than the outdoor heat exchange temperature Th, the outdoor fan rotational speed Cf is lowered, so that the outdoor air having an outdoor air temperature To lower than the outdoor heat exchange temperature Th is reduced. The power consumption of the outdoor fan 24 can be reduced by reducing the outdoor fan rotation speed Cf while preventing the outdoor heat exchanger 23 from passing more than necessary so that the time during which the pressure difference ΔP is equal to or less than the threshold pressure difference Pth does not increase. Can be reduced.

  When the temperature difference ΔT is less than the fourth threshold temperature (-1 ° C. in the present embodiment), the outdoor fan rotation speed Cf is set to 0 rpm, so that the outdoor heat is generated by the outdoor air To that is lower than the outdoor heat exchange temperature Th. Since the exchanger 23 is cooled, the outdoor fan 24 is stopped while preventing the time during which the pressure difference ΔP is equal to or lower than the threshold pressure difference Pth from being longer than when the temperature difference ΔT is equal to or higher than the fourth threshold temperature. As a result, the power consumption can be further reduced as compared with the case where the temperature difference ΔT is equal to or higher than the fourth threshold temperature.

The fan rotation speed table 300 considers the relationship between the temperature difference ΔT and the pressure difference ΔP described above, obtains the outdoor fan rotation speed Cf according to the temperature difference ΔT by performing a test in advance, and controls the outdoor unit. This is stored in the storage unit 220 of the means 200.
<Processing related to outdoor fan control after compressor stop>

  Next, the control of the outdoor fan 23 when the compressor 21 is stopped will be described with reference to FIG. FIG. 3 is a flowchart showing a flow of processing performed by the CPU 210 of the outdoor unit control means 200 when the air conditioner 1 stops the cooling operation or the heating operation by a user's operation stop instruction or thermo-off. In FIG. 3, ST represents a process step, and the number following this represents a step number. Note that FIG. 3 mainly describes processing related to the present invention, and other processing, for example, an air conditioner such as operation control of the compressor 21 according to a user's request during air-conditioning operation. Description of processing related to general control 1 is omitted.

  When the air conditioner 1 is performing a cooling operation or a heating operation, when the operation is stopped by an operation stop instruction or a thermo-off by the user, the CPU 210 determines the operation mode that has been performed so far (ST1). . Specifically, the CPU 210 determines whether the operation that has been performed until the operation is stopped by a user's operation stop instruction or thermo-off is a cooling operation or a heating operation.

  Next, the CPU 210 takes in the outside air temperature To detected by the outside air temperature sensor 76 and the outdoor heat exchange temperature Th detected by the heat exchange temperature sensor 75 via the sensor input unit 240, and the outdoor heat exchange temperature Th from the outside air temperature To. Is subtracted to calculate the temperature difference ΔT (ST2).

  Next, the CPU 210 refers to the fan rotation speed table 300 stored in the storage unit 220 and extracts the outdoor fan rotation speed Cf corresponding to the temperature difference ΔT calculated in ST1. Specifically, the CPU 210 first determines whether or not the temperature difference ΔT calculated in ST1 is 1 ° C. or more (ST3).

  If the calculated temperature difference ΔT is 1 ° C. or more (ST3-Yes), the CPU 210 extracts the outdoor fan rotation speed Cf = 0 rpm from the fan rotation speed table 300 if the operation mode determined in ST1 is the cooling operation. Alternatively, if the operation mode determined in ST1 is the heating operation, the outdoor fan rotation speed Cf = 800 rpm is extracted from the fan rotation speed table 300 (ST11), and the process proceeds to ST6.

  If the calculated temperature difference ΔT is not 1 ° C. or more (ST3-No), the CPU 210 determines whether or not the calculated temperature difference ΔT is less than −1 ° C. (ST4).

  If the calculated temperature difference ΔT is less than −1 ° C. (ST4-Yes), the CPU 210 extracts the outdoor fan rotation speed Cf = 800 rpm from the fan rotation speed table 300 if the operation mode determined in ST1 is the cooling operation. Alternatively, if the operation mode determined in ST1 is the heating operation, the outdoor fan rotation speed Cf = 0 rpm is extracted from the fan rotation speed table 300 (ST12), and the process proceeds to ST6.

  If the calculated temperature difference ΔT is not less than −1 ° C. (ST4-Yes), that is, if the calculated temperature difference ΔT is not less than −1 ° C. and less than 1 ° C., the CPU 210 has the same rotational speed in the cooling operation / heating operation. The outdoor fan rotational speed Cf = 400 rpm is extracted from the fan rotational speed table 300, and the process proceeds to ST6.

The CPU 210 that has finished any one of ST5, ST11, and ST12 drives the outdoor fan 24 at the outdoor fan rotational speed Cf extracted in any of ST4, ST10, and ST11 (when the outdoor fan rotational speed Cf = 400 rpm or 800 rpm). Or the outdoor fan 24 is stopped (when the outdoor fan rotation speed Cf = 0 rpm) (ST6).
CPU210 which finished the process of ST6 stops the compressor 21 (ST7).

  Next, the CPU 210 takes in the high pressure Ph detected by the discharge pressure sensor 71 and the low pressure Pl detected by the suction pressure sensor 72 via the sensor input unit 240, and calculates the pressure difference ΔP between the high pressure Ph and the low pressure Pl (ST8). ).

  Next, CPU 210 determines whether or not pressure difference ΔP calculated in ST8 is less than threshold pressure difference Pth (ST9). If the calculated pressure difference ΔP is less than the threshold pressure difference Pth (ST9-Yes), the CPU 210 stops when the outdoor fan 24 is driven at the outdoor fan rotation speed Cf at ST6, and stops the outdoor fan 24 at ST6. If so, that state is maintained (ST10) and the process is terminated.

  On the other hand, if calculated pressure difference ΔP is not less than threshold pressure difference Pth (ST9-No), CPU 210 returns the process to ST8. In this case, the CPU 210 periodically takes in the high pressure Ph and the low pressure Pl (for example, every 30 seconds), and repeats the processes of ST8 to ST9 until the pressure difference ΔP becomes less than the threshold pressure difference Pth in ST9.

  If the pressure difference ΔP is less than the threshold pressure difference Pth in ST9, that is, the process in ST9 is “Yes”, and the compressor 21 can be restarted. As described above, in order to determine whether or not the compressor 21 can be restarted after the process of ST9, the process of ST8 to ST9 is required even when the outdoor fan 24 is stopped in ST6.

  As described above, in the air conditioner 1 of the present embodiment, the temperature difference between the operation mode, the outside air temperature To, and the outdoor heat exchanger temperature Th when the air conditioner 1 is operating after the compressor 21 is stopped. The outdoor fan rotation speed Cf is determined based on ΔT, and the outdoor fan 24 is controlled such that the outdoor fan 24 is driven or stopped at the determined outdoor fan rotation speed Cf. As a result, the time taken to equalize the refrigerant circuit 10 after the operation is stopped can be shortened, and the compressor 21 can be restarted early after the compressor 21 is stopped.

  In the embodiment described above, when the outdoor fan 24 is driven at the outdoor fan rotation speed Cf when the operation of the air conditioner 1 is stopped, the outdoor fan 24 is driven until the pressure difference ΔP becomes equal to or less than the threshold pressure difference Pth. The case of making it explained was explained. Instead of this, the outdoor fan 24 may be driven for a predetermined time from the operation stop time of the compressor 21 when the operation of the air conditioner 1 is stopped. The predetermined time in this case may be determined by performing a test or the like in advance, and may be a time necessary for the pressure difference ΔP to be equal to or less than the threshold pressure difference Pth.

  Further, in the embodiment described above, before the compressor 21 is stopped in ST7 of FIG. 3, the processing of ST1 to ST6 of FIG. 3 is performed to drive or stop the outdoor fan 24 at the outdoor fan rotation speed Cf. However, after the process of ST7 is performed first and the compressor 21 is stopped, the processes of ST1 to ST6 may be performed.

  In the embodiment described above, in the fan rotation speed table 300 of FIG. 2, the cooling reference rotation speed and the heating reference rotation speed are set to the same 400 rpm, but the cooling reference rotation speed and the heating reference rotation speed are different. It may be the rotational speed.

  Further, in the operation mode: cooling, the outdoor fan rotation speed Cf is determined by dividing the temperature difference ΔT into three ranges of less than −1 ° C./−1° C. or more and less than 1 ° C./1° C. or more. The range of ΔT may be increased. For example, the outdoor fan rotation speed Cf when the temperature difference ΔT is 1 ° C. or more and less than 3 ° C. may be 200 rpm, and the outdoor fan rotation speed Cf when the temperature difference ΔT is 3 ° C. or more may be 0 rpm (stop).

  Furthermore, in the operation mode: heating, the outdoor fan rotation speed Cf is determined by dividing the temperature difference ΔT into three ranges of less than −1 ° C./−1° C. or more and less than 1 ° C./1° C. or more. The range of the difference ΔT may be increased. For example, the outdoor fan rotation speed Cf when the temperature difference ΔT is −3 ° C. or more and less than −1 ° C. may be 200 rpm, and the outdoor fan rotation speed Cf when the temperature difference ΔT is less than −3 ° C. may be 0 rpm (stop).

DESCRIPTION OF SYMBOLS 1 Air conditioner 2 Outdoor unit 3 Indoor unit 10 Refrigerant circuit 21 Compressor 23 Outdoor heat exchanger 24 Outdoor fan 31 Indoor heat exchanger 71 Discharge pressure sensor 72 Suction pressure sensor 75 Heat exchange temperature sensor 76 Outside air temperature sensor 200 Outdoor unit control Means 210 CPU
220 Storage unit 300 Fan speed table Cf Outdoor fan speed Ph High pressure Pl Low pressure ΔP Pressure difference Th Outdoor heat exchange temperature To Outdoor temperature ΔT Temperature difference

Claims (7)

Compressor, four-way valve, outdoor heat exchanger, outdoor fan, outdoor air temperature detecting means for detecting the outdoor air temperature, and outdoor heat exchanger temperature detection for detecting the outdoor heat exchanger temperature which is the temperature of the outdoor heat exchanger An outdoor unit having means;
An indoor unit having an indoor heat exchanger;
Control means for controlling driving of the compressor and the outdoor fan;
An air conditioner having
The control means, when stopping the compressor,
The rotation speed is based on a temperature difference obtained by subtracting the outdoor heat exchange temperature detected by the outdoor heat exchange temperature detection means from the operation mode at the time of stopping the air conditioning operation and the outside air temperature detected by the outside air temperature detection means. Controlling the outdoor fan,
An air conditioner characterized by that. The operation mode is a cooling operation,
When stopping the compressor in the cooling operation,
The rotational speed of the outdoor fan when the temperature difference is less than a predetermined first threshold temperature is higher than the rotational speed of the outdoor fan when the temperature difference is equal to or higher than the first threshold temperature.
The air conditioner according to claim 1. When the temperature difference is equal to or higher than a predetermined second threshold temperature higher than the first threshold temperature, the outdoor fan is stopped;
The air conditioner according to claim 2. The operation mode is a heating operation,
When stopping the compressor in the heating operation,
The rotational speed of the outdoor fan when the temperature difference is equal to or higher than a predetermined third threshold temperature is higher than the rotational speed of the outdoor fan when the temperature difference is lower than the third threshold temperature.
The air conditioner according to claim 1. The outdoor fan is stopped when the temperature difference is less than a predetermined fourth threshold temperature lower than the third threshold temperature;
The air conditioner according to claim 4. High pressure detection means for detecting the pressure on the high pressure side of the compressor, and low pressure detection means for detecting the pressure on the low pressure side of the compressor,
The control means, after stopping the compressor, until the pressure difference between the high-pressure side pressure detected by the high-pressure detection means and the low-pressure side pressure detected by the low-pressure detection means falls below a predetermined threshold pressure difference. Continue to drive the outdoor fan,
The air conditioner according to any one of claims 1, 2, 4, and 5. The control means continues to drive the outdoor fan for a predetermined time after stopping the compressor.
The air conditioner according to any one of claims 1, 2, 4, and 5.

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