JP2017150678A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner in which refrigerant flow noise generated in a stopped indoor unit during heating operation is reduced.SOLUTION: CPU 210 takes liquid side refrigerant temperatures TL of each of the indoor units 5, calculates an average value TLave under application of liquid side refrigerant temperatures TL of the operation indoor unit 5 of the taken liquid side refrigerant temperatures TL, subtracts the average value TLave from the liquid side refrigerant temperatures TL of the stopped indoor unit 5 to calculate a second temperature difference ΔTb. CPU 210 adds the number of pulses added with the number of pulses corresponding to a value of a second temperature difference ΔTb to the number of pulses PLS applied to an expansion valve 24 of the present stopped indoor unit 5 to the corresponding expansion valve 24 only when a refrigerant overcooling degree SC in the stopped indoor unit 5 is higher than a threshold refrigerant overcooling degree in the case that the calculated second temperature difference ΔTb is lower than a second threshold temperature difference.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an air conditioner in which a plurality of indoor units are connected to an outdoor unit by refrigerant piping.

  Conventionally, as an air conditioner, a plurality of indoor units are connected to one outdoor unit by liquid pipes and gas pipes, and a cooling operation or a heating operation can be performed simultaneously by a plurality of indoor units. Are known. The outdoor unit of such an air conditioner is provided with the same number of expansion valves as the number of indoor units, and the refrigerant flow rate in each indoor unit is adjusted by adjusting the opening degree of the expansion valve corresponding to each indoor unit. Can be adjusted.

  When heating operation is performed with the air conditioner as described above, indoor units that are thermo-off or indoor units that have stopped operating (hereinafter, unless otherwise required to be individually stopped) If the expansion valve corresponding to the stopped indoor unit is fully closed, refrigerant or refrigeration oil may accumulate in the indoor heat exchanger of the stopped indoor unit. In order to solve such problems, normally, the expansion valve corresponding to the stop indoor unit is set to a very small opening so that a small amount of refrigerant flows through the stop indoor unit, thereby preventing the refrigerant and refrigerating machine oil from staying. It is out.

  Generally, when the opening degree of the expansion valve is set to a minute opening degree, the opening degree accuracy often varies, and the opening degree may be larger than the assumed opening degree. In this case, a large amount of refrigerant flows through the stop indoor unit, and the refrigerant flow noise increases. In the stopped indoor unit, the indoor fan is stopped and there is no noise generated when the indoor fan is driven. Therefore, the refrigerant flow noise may be a problem.

  In order to solve the above problem, in the air conditioner described in Patent Document 1, a check valve and a capillary tube are connected in parallel to the expansion valve, and the corresponding expansion valve opening is fully closed in the stop indoor unit. . Thus, in the stop indoor unit, the refrigerant is allowed to flow through the check valve and the capillary tube, thereby preventing the refrigerant and the refrigerating machine oil from collecting in the indoor heat exchanger while minimizing the refrigerant flow noise.

JP-A-7-310962

  By the way, when the heating operation is performed by the air conditioner, the opening degree of the expansion valve corresponding to the operating indoor unit (hereinafter referred to as the operating indoor unit) is determined by the refrigerant temperature discharged from the compressor. Target discharge temperature control is performed to uniformly adjust a certain discharge temperature to a target value (hereinafter referred to as a target discharge temperature). Here, the target discharge temperature is, for example, that of the compressor related to the condensation temperature in the indoor heat exchanger functioning as a condenser, the evaporation temperature in the outdoor heat exchanger functioning as an evaporator, and the refrigerant circulation amount of the air conditioner. It can be calculated using the number of rotations.

  As described above, in the target discharge temperature control, the opening degree of each expansion valve corresponding to the operation indoor unit is uniformly adjusted. At this time, if the air conditioning capacity of each indoor unit is different, or if the air conditioning capacity of each indoor unit is the same, the rotational speed of the indoor fan is different, that is, the amount of heat exchange in the indoor heat exchanger is different. There is a risk that the flow rate of the refrigerant, which is the temperature of the refrigerant flowing out from the indoor heat exchanger of each indoor unit, varies due to the deviation of the refrigerant flow rate in the unit. When the liquid pipe refrigerant temperature varies, the refrigerant temperature sucked into the compressor fluctuates, and as a result, the discharge temperature fluctuates and the target discharge temperature control becomes unstable. Therefore, in order to stabilize the target discharge temperature control, for example, the average value of the liquid pipe refrigerant temperature of the operating indoor unit is calculated, and the average value of the liquid pipe refrigerant temperature calculated for all the indoor units including the stopped indoor unit is It is conceivable that all liquid pipe refrigerant temperatures are set to the same temperature by adjusting the respective opening degrees of the expansion valves so as to be.

  When adjusting each expansion valve opening degree so that the liquid pipe refrigerant temperature is the average value calculated for all indoor units including the stopped indoor units described above, for example, some of the stopped indoor units are If the heating load suddenly increases as in the case of starting, the refrigerant circulation rate may be transiently insufficient. When the refrigerant circulation amount is transiently insufficient, the condensing pressure in the indoor heat exchanger of the operating indoor unit and the stopped indoor unit is transiently reduced, resulting in the refrigerant outlet of each indoor heat exchanger The refrigerant supercooling degree on the side becomes small. At this time, if the expansion valve opening corresponding to the stop indoor unit is increased in order to make the liquid pipe refrigerant temperature the same, the refrigerant in the gas-liquid two-phase state flows through the indoor unit and the refrigerant flow noise is noticeable. There was a risk of discomfort to the user.

  The present invention solves the above-described problems, and an object thereof is to provide an air conditioner that reduces refrigerant flow noise generated in a stop indoor unit during heating operation.

  In order to solve the above problems, an air conditioner of the present invention includes an outdoor unit, a plurality of indoor units, and a refrigerant circuit in which the outdoor unit and the plurality of indoor units are connected by a refrigerant pipe. The plurality of indoor units have indoor heat exchangers. The number of outdoor units is the same as the number of compressors, four-way valves, outdoor heat exchangers, and indoor units. The number of indoor units is the same as the number of expansion valves and indoor units. Liquid-side temperature detecting means for detecting a liquid-side refrigerant temperature that is the temperature of the refrigerant flowing out from the tank. When the air conditioner is performing the heating operation, when the operation indoor unit and the stop indoor unit coexist, the operation indoor unit is set so that the discharge temperature, which is the refrigerant temperature discharged from the compressor, becomes the target discharge temperature. Expansion valve corresponding to the stop indoor unit so that the liquid side refrigerant temperature detected by the liquid side temperature detecting means of the stop indoor unit becomes a predetermined temperature while performing target discharge temperature control for adjusting the opening degree of the expansion valve corresponding to In order to increase the opening of the expansion valve corresponding to the stopped indoor unit in the stopped indoor unit liquid temperature adjustment control, the indoor heat exchanger of the stopped indoor unit is adjusted. Control means for increasing the opening degree of the expansion valve corresponding to the stop indoor unit whose refrigerant subcooling degree on the refrigerant outlet side is greater than a predetermined threshold refrigerant subcooling degree.

  The air conditioner of the present invention configured as described above has an expansion valve opening corresponding to the indoor unit when there is no risk of gas-liquid two-phase refrigerant flowing through the stopped indoor unit in the stopped indoor unit liquid temperature adjustment control. Control means to increase. Thereby, the user's discomfort caused by the refrigerant flow sound of the gas-liquid two-phase refrigerant can be reduced.

It is explanatory drawing of the air conditioning apparatus which is embodiment of this invention, (A) is a refrigerant circuit figure, (B) is a block diagram of an outdoor unit control means. It is a main routine of the process which the outdoor unit control means performs in the embodiment of the present invention. It is a subroutine of the process which the outdoor unit control means performs in the embodiment of the present invention, and shows the process related to the diversion adjustment of the driving indoor unit. It is a subroutine of the process which the outdoor unit control means performs in embodiment of this invention, and shows the process in connection with the shunt adjustment of a stop indoor unit.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. As an embodiment, an air conditioner will be described as an example in which a plurality of indoor units are connected in parallel to one outdoor unit through a refrigerant pipe, and a cooling operation or a heating operation can be performed simultaneously in all the indoor units. 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, the air conditioner 1 according to this embodiment includes six indoor units 5 in one outdoor unit 2 and six liquid pipes 8 and 6 that are the same as the number of indoor units 5. The gas pipes 9 are connected in parallel. Specifically, one end of each of the six liquid pipes 8 is connected to six liquid side shut-off valves 27 provided in the outdoor unit 2, and the other end of each of the six liquid pipes 8 and the six indoors. The liquid pipe connection part 52 of the machine 5 is connected. Further, one end of each of the six gas pipes 9 is connected to six gas side shut-off valves 28 provided in the outdoor unit 2, and the other end of each of the six gas pipes 9 and the six indoor units 5 are connected. A gas pipe connecting portion 53 is connected. As described above, the outdoor unit 2 and the six indoor units 5 are connected by the six liquid pipes 8 and the six gas pipes 9 to constitute the refrigerant circuit 10 of the air conditioner 1. In FIG. 1A, six indoor units 5, six liquid pipes 8, six gas pipes 9, six liquid side shut-off valves 27, and six gas side shut-off valves 28 are shown. Are drawing only three each.

  The outdoor unit 2 includes a compressor 21, a four-way valve 22, an outdoor heat exchanger 23, six expansion valves 24, an accumulator 25, an outdoor fan 26, the six liquid side closing valves 27 and Six gas side shut-off valves 28 and an outdoor unit control means 200 are provided. These devices other than the outdoor fan 26 and the outdoor unit control means 200 are connected to each other through refrigerant pipes described in detail below to form an outdoor unit refrigerant circuit 20 that forms part of the refrigerant circuit 10. Yes. In FIG. 1A, only three expansion valves 24 are drawn.

  The compressor 21 is a variable capacity compressor that can vary its operating capacity by being driven by a motor (not shown) whose rotational speed is controlled by an inverter. A refrigerant discharge port of the compressor 21 and a port a of the four-way valve 22 are connected by a discharge pipe 41. The refrigerant suction side of the compressor 21 and the refrigerant outflow side of the accumulator 25 are connected by a suction pipe 42.

  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. As described above, the port a and the refrigerant discharge port of the compressor 21 are connected by the discharge pipe 41. The refrigerant outlet 43 is connected to the port b and one refrigerant inlet / outlet of the outdoor heat exchanger 23. The port c and the refrigerant inflow side of the accumulator 25 are connected by a refrigerant pipe 46. One end of the outdoor unit gas pipe 45 is connected to the port d. The other end of the outdoor unit gas pipe 45 is connected to one end of each of six outdoor unit gas distribution pipes 45a (three of which are drawn in FIG. 1A). The other end of each of the branch pipes 45 a is connected to six gas side shut-off valves 28.

  The outdoor heat exchanger 23 exchanges heat between the outside air taken into the outdoor unit 2 from the suction port (not shown) and the refrigerant by the rotation of the outdoor fan 26. As described above, one refrigerant inlet / outlet of the outdoor heat exchanger 23 and the port b of the four-way valve 22 are connected by the refrigerant pipe 43. One end of the outdoor unit liquid pipe 44 is connected to the other refrigerant inlet / outlet of the outdoor heat exchanger 23. The outdoor heat exchanger 23 functions as a condenser when the refrigerant circuit 10 is in a cooling cycle, and functions as an evaporator when the refrigerant circuit 10 is in a heating cycle.

  One end of each of six outdoor unit liquid distribution pipes 44a (three of which are drawn in FIG. 1A) is connected to the other end of the outdoor unit liquid pipe 44, and six outdoor unit liquid distribution pipes 44a are connected. The other end of each is connected to six liquid side closing valves 27. An expansion valve 24 is provided in each outdoor unit liquid distribution pipe 44a. The opening degrees of all the six expansion valves 24 are controlled by the outdoor unit control means 200. By controlling the opening degree of each expansion valve 24, the amount of refrigerant flowing through the six indoor units 5 connected to each expansion valve 24 is adjusted. The six expansion valves 24 are electronic expansion valves driven by a pulse motor (not shown), and the opening degree is adjusted by the number of pulses given to the pulse motor.

  As described above, in the accumulator 25, the refrigerant inflow side and the port c of the four-way valve 22 are connected by the refrigerant pipe 46, and the refrigerant outflow side and the refrigerant suction port of the compressor 21 are connected by the suction pipe 42. The accumulator 25 separates the inflowing refrigerant into a gas refrigerant and a liquid refrigerant, and causes the compressor 21 to suck only the gas refrigerant through the suction pipe 42.

  The outdoor fan 26 is a propeller fan formed of a resin material disposed in the vicinity of the outdoor heat exchanger 23, and the outdoor fan 26 is rotated by a fan motor (not shown) so that the outdoor fan 2 is not shown. Outside air is taken into the interior of the outdoor unit 2 from the suction port, and the outside air heat-exchanged with the refrigerant flowing in the outdoor heat exchanger 23 is discharged to the outside of the outdoor unit 2 from a blower outlet (not shown) provided in 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 41 has a high pressure sensor 31 that detects a discharge pressure that is a pressure of the refrigerant discharged from the compressor 21, and a temperature of the refrigerant discharged from the compressor 21. A discharge temperature sensor 33 for detecting the discharge temperature is provided. In the refrigerant pipe 46, near the refrigerant inflow side of the accumulator 25, there are a low-pressure sensor 32 that detects the pressure of the refrigerant sucked into the compressor 21 and a suction temperature sensor 34 that detects the temperature of the refrigerant sucked into the compressor 21. Is provided.

  A refrigerant temperature sensor 35 that detects the temperature of the refrigerant flowing into the outdoor heat exchanger 23 when the outdoor heat exchanger 23 functions as an evaporator is provided in the vicinity of the outdoor heat exchanger 23 in the outdoor unit liquid pipe 44. ing. Between the expansion valve 24 and the liquid side closing valve 27 in the six outdoor unit liquid distribution pipes 44a, a liquid side temperature sensor 36 that detects a liquid side refrigerant temperature that is the temperature of the refrigerant flowing through the outdoor unit liquid distribution pipe 44a (the present invention). In FIG. 1A, three of them are drawn). In the six outdoor unit gas branch pipes 45a, gas side temperature sensors 37 for detecting the gas side refrigerant temperature which is the temperature of the refrigerant flowing through the outdoor unit gas branch pipe 45a (three of them are drawn in FIG. 1A) Is provided. An outdoor air temperature sensor 38 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, and as shown in FIG. 1B, a CPU 210, a storage unit 220, a communication unit 230, The sensor input unit 240 is provided.

  The storage unit 220 includes a ROM and a RAM, and includes detection values corresponding to control programs for the outdoor unit 2 and detection signals from various sensors, driving states of the compressor 21 and the outdoor fan 26, and six indoor units 5. The operation information (including operation / stop information, set temperature information, etc.) transmitted from each of these is stored. The communication unit 230 is an interface that performs communication with each of the six indoor units 5. The sensor input unit 240 captures detection results from various sensors of the outdoor unit 2 and outputs them to the CPU 210. The CPU 210 periodically captures the detection values of various sensors via the sensor input unit 240 (for example, every minute), and indicates the operation start / stop transmitted from each of the six indoor units 5. A signal including operation information (set temperature, room temperature, etc.) is input via the communication unit 230. The CPU 210 performs the opening control of each expansion valve 24 and the drive control of the compressor 21 and the outdoor fan 26 based on these various pieces of input information.

  Next, the six indoor units 5 will be described. The six indoor units 5 all have the same configuration, and include an indoor heat exchanger 51, a liquid pipe connection part 52, a gas pipe connection part 53, and an indoor fan 54. And these each apparatus except the indoor fan 54 is mutually connected by each refrigerant | coolant piping explained in full detail below, and the indoor unit refrigerant circuit 50 which makes a part of the refrigerant circuit 10 is comprised.

The indoor heat exchanger 51 exchanges heat between the refrigerant and indoor air taken into the indoor unit 5 from a suction port (not shown) provided in the indoor unit 5 by rotation of the indoor fan 54. One refrigerant inlet / outlet of the indoor heat exchanger 51 and the liquid pipe connecting portion 52 are connected by an indoor unit liquid pipe 71. The other refrigerant inlet / outlet of the indoor heat exchanger 51 and the gas pipe connecting portion 53 are connected by an indoor unit gas pipe 72. Each refrigerant pipe is connected to the liquid pipe connecting part 52 and the gas pipe connecting part 53 by welding, a flare nut or the like.
The indoor heat exchanger 51 functions as an evaporator when the indoor unit 5 performs a cooling operation, and functions as a condenser when the indoor unit 5 performs a heating operation.

  The indoor fan 54 is a crossflow fan formed of a resin material disposed in the vicinity of the indoor heat exchanger 51, and is rotated by a fan motor (not shown) to enter the indoor unit 5 from the suction port (not shown). Air is taken in and the indoor air heat-exchanged with the refrigerant in the indoor heat exchanger 51 is supplied into the room from an unillustrated outlet provided in the indoor unit 5. An indoor temperature sensor 61 that detects the temperature of the indoor air flowing into the indoor unit 5, that is, the indoor temperature, is provided near the suction port (not shown) of the indoor unit 5.

  Next, the flow of the refrigerant and the operation of each part in the refrigerant circuit 10 when the air-conditioning apparatus 1 of the present embodiment performs the heating operation will be described with reference to FIG. In the following description, the case where all the six indoor units 5 are performing the heating operation will be described. In FIG. 1A, the arrows indicate the flow of the refrigerant during the heating operation in the refrigerant circuit 10, and, for the four-way valve 22, the communication state between the ports during the heating operation is indicated by a solid line. .

  In addition, although detailed description is abbreviate | omitted about the flow of the refrigerant | coolant in the refrigerant circuit 10 when the air conditioning apparatus 1 performs cooling operation, and operation | movement of each part, the communication state between each port of the four-way valve 22 at the time of cooling operation is 1A, the outdoor heat exchanger 23 functions as a condenser, and each indoor heat exchanger 51 functions as an evaporator.

  When the indoor unit 5 performs the heating operation, the four-way valve 22 is in the state shown by the solid line in FIG. 1A, that is, the port a and the port d of the four-way valve 22 communicate with each other, and the port b and the port c are connected. It is switched to communicate. Thereby, the refrigerant circuit 10 enters a state in which the refrigerant flows in the direction indicated by the arrow in FIG. 1A, and the outdoor heat exchanger 23 functions as an evaporator, and each indoor heat exchanger 51 functions as a condenser.

  When the compressor 21 is started in the state of the refrigerant circuit 10 as described above, the high-pressure refrigerant discharged from the compressor 21 flows into the four-way valve 22 from the discharge pipe 41 and passes through the outdoor unit gas pipe 45 from the four-way valve 22. The flow is divided into six outdoor unit gas distribution pipes 45a. The refrigerant that has flowed from the outdoor unit gas distribution pipes 45 a into the gas pipes 9 through the gas side shut-off valves 28 flows into the indoor units 5 through the gas side connection portions 53.

  The refrigerant flowing into each indoor unit 5 flows through each indoor unit gas pipe 72 and flows into each indoor heat exchanger 51, and the indoor air and heat taken into the interior of each indoor unit 2 by the rotation of each indoor fan 54. Exchange and condense. The refrigerant that has flowed out from each indoor heat exchanger 51 to each indoor unit liquid pipe 71 flows out to each liquid pipe 8 via each liquid pipe connection portion 52, flows through each liquid pipe 8, and opens each liquid side shut-off valve 27. Through the outdoor unit 2.

  The refrigerant flowing into the indoor unit 2 flows through each outdoor unit liquid distribution pipe 44 a, is decompressed by each expansion valve 24, flows out to the outdoor unit liquid pipe 44, joins at the outdoor unit liquid pipe 44, and flows into the outdoor heat exchanger 23. To do. The refrigerant 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 26, and flows out from the outdoor heat exchanger 23 to the refrigerant pipe 43. The refrigerant flowing through the refrigerant pipe 43 flows to the four-way valve 22 and the refrigerant pipe 46 and flows into the accumulator 25, and is separated into a gas refrigerant and a liquid refrigerant by the accumulator 25. The gas refrigerant flowing out from the accumulator 25 to the suction pipe 42 flows through the suction pipe 42 and is sucked into the compressor 21 and compressed again.

  As described above, when the air conditioner 1 is performing the heating operation, the opening degree of each expansion valve 24 is a target discharge temperature control in which the discharge temperature, which is the refrigerant temperature discharged from the compressor 21, is the target discharge temperature. The liquid-side refrigerant temperature detected by each liquid-side temperature sensor 36 is adjusted by the liquid temperature adjustment control so as to be the same temperature. In addition, the liquid temperature adjustment control is stopped from the operation indoor unit liquid temperature adjustment control in which the liquid side refrigerant temperature of the indoor unit 5 that is in operation (hereinafter referred to as the operation indoor unit 5) becomes the same temperature. This is comprised of two types of control: stop indoor unit liquid temperature adjustment control so that the liquid side refrigerant temperature of the indoor unit 5 (hereinafter referred to as the stop indoor unit 5) is the same.

  Below, target discharge temperature control is demonstrated first, and liquid temperature adjustment control (operation indoor unit liquid temperature adjustment control and stop indoor unit liquid temperature adjustment control) is demonstrated next. In the following description, the liquid-side refrigerant temperature detected by the liquid-side temperature sensor 36 is TL, the maximum / minimum value of the liquid-side refrigerant temperature TL of the operation indoor unit 5 is TLmax / TLmin, and the liquid of the operation indoor unit 5 is The temperature difference obtained by subtracting the minimum value TLmin from the maximum value TLmax (hereinafter referred to as the first temperature difference) is ΔTa, and the average value is calculated from the liquid side refrigerant temperature TL of the operating indoor unit 5 A temperature difference obtained by subtracting TLave (hereinafter referred to as a second temperature difference) is defined as ΔTb.

  Further, the discharge pressure of the compressor 21 detected by the high pressure sensor 31 is Hp, and a high pressure saturation temperature calculated using the discharge pressure Hp (condensation temperature in the indoor heat exchanger 51 of each indoor unit 5 that functions as a condenser during heating operation). Is equivalent to Thp, and SC is the refrigerant subcooling degree on the refrigerant outlet side of each indoor heat exchanger 51 obtained by subtracting the liquid refrigerant temperature TL of each indoor unit 5 from the high-pressure saturation temperature Thp.

Further, the number of pulses applied to each expansion valve 24 to adjust the opening degree of each expansion valve 24 corresponds to PLS, the initial number of pulses applied to the expansion valve 24 corresponding to the operation indoor unit 5 corresponds to PLS1, and the stop indoor unit 5. The initial pulse number applied to the expansion valve 24 is PLS2, and the maximum value / minimum value of the pulse number PLS applied to the expansion valve 24 corresponding to the operating indoor unit 5 is PLSmax / PLSmin, respectively.
<Target discharge temperature control>

  In the target discharge temperature control, the opening degree of the expansion valve 24 corresponding to the operation indoor unit 5 is adjusted so that the discharge temperature detected by the discharge temperature sensor 33 becomes the target discharge temperature. Specifically, first, the target discharge temperature is determined by the condensation temperature in the indoor heat exchanger 51 functioning as a condenser, the evaporation temperature in the outdoor heat exchanger 23 functioning as an evaporator, and the refrigerant circuit 10. It is calculated using the rotation speed of the compressor 21 related to the refrigerant circulation amount. The condensation temperature is calculated using the discharge pressure Hp as described above. The evaporation temperature is calculated using the suction pressure that is the pressure of the refrigerant sucked into the compressor 21 detected by the low pressure sensor 32. The above-described initial pulse number PLS2 is added to the expansion valve 24 corresponding to the stop indoor unit 5, and the opening degree of the expansion valve 24 is set to an opening degree corresponding to the initial pulse number PLS2.

  Then, the calculated target discharge temperature and the discharge temperature detected by the discharge temperature sensor 33 are compared, and when the detected discharge temperature is higher than the target discharge temperature, the opening degree of the expansion valve 24 corresponding to the operation indoor unit 5 Is uniformly larger than the current opening. Thereby, the refrigerant | coolant amount suck | inhaled by the compressor 21 increases and discharge temperature falls. When the opening degree of each expansion valve 24 is uniformly increased from the current opening degree, it corresponds to the temperature difference between the discharge temperature detected at the pulse number PLS currently applied to each expansion valve 24 and the target discharge temperature. A pulse number PLS is added which is obtained by uniformly adding the number of minutes.

When the detected discharge temperature is lower than the target discharge temperature, the opening degree of the expansion valve 24 corresponding to the operation indoor unit 5 is uniformly made smaller than the current opening degree. Thereby, the refrigerant | coolant amount suck | inhaled by the compressor 21 reduces and discharge temperature rises. In addition, when making the opening degree of each expansion valve 24 uniformly smaller than the current opening degree, it corresponds to the temperature difference between the discharge temperature detected from the pulse number PLS currently applied to each expansion valve 24 and the target discharge temperature. The pulse number PLS obtained by subtracting the minute pulse number is added.
<Liquid temperature adjustment control>

  In the liquid temperature adjustment control, the opening degree of each expansion valve 24 is adjusted so that the liquid side refrigerant temperatures TL detected by the liquid side temperature sensors 36 of the operation indoor unit 5 and the stop indoor unit 5 become the same temperature.

  When the target discharge temperature control described above is performed, the opening degree of each expansion valve 24 corresponding to the operation indoor unit 5 is uniformly adjusted as described above. At this time, when the air conditioning capability of each indoor unit 5 is different, or even when the indoor unit 5 has the same air conditioning capability, the number of rotations of the indoor fan 54 is different, that is, the heat exchange amount in the indoor heat exchanger 51 is different. May cause unevenness in the refrigerant flow rate among the plurality of operating indoor units 5, which may cause variation in the liquid-side refrigerant temperature TL. If the liquid-side refrigerant temperature TL varies, the refrigerant temperature sucked into the compressor 21 fluctuates, and as a result, the discharge temperature fluctuates and the target discharge temperature control may become unstable. Therefore, the liquid temperature adjustment control is performed so that all the liquid side refrigerant temperatures TL become the same temperature.

In the liquid temperature adjustment control, the operation indoor unit liquid temperature adjustment control performed on the operation indoor unit 5 and the stop indoor unit liquid temperature adjustment control performed on the stop indoor unit 5 are individually performed. Hereinafter, the operation indoor unit liquid temperature adjustment control and the stop indoor unit liquid temperature adjustment control will be described in this order.
<Operating indoor unit fluid temperature adjustment control>

  In the operation indoor unit liquid temperature adjustment control, first, the liquid side refrigerant temperature TL detected by each liquid side temperature sensor 36 of the operation indoor unit 5 is taken in, and the maximum value TLmax and the minimum value are obtained from each liquid side refrigerant temperature TL taken in. TLmin is extracted. Then, a first temperature difference ΔTa is calculated as a difference between the extracted maximum value TLmax and minimum value TLmin, and the opening degree of the expansion valve 24 corresponding to each operating indoor unit 5 is determined according to the value of the first temperature difference ΔTa. Adjusted.

  Specifically, for the expansion valve 24 to which the maximum value PLSmax is added, a pulse number obtained by subtracting a value corresponding to the first temperature difference ΔTa from the maximum value PLSmax is added to the expansion valve 24, and the expansion valve 24 The opening degree of 24 becomes small. On the other hand, for the expansion valve 24 to which the minimum value PLSmin is added, the number of pulses obtained by adding the same value as the value obtained by subtracting the minimum value PLSmin from the maximum value PLSmax is added to the expansion valve 24. The opening of becomes larger.

In the operation indoor unit liquid temperature adjustment control, by adjusting the opening degree of the expansion valve 24 described above periodically (for example, every minute), the refrigerant flow rate in each operation indoor unit 5 is changed to the capability of each operation indoor unit 5. The liquid side refrigerant temperature TL detected by each liquid side temperature sensor 36 has the same value.
<Stopping indoor unit liquid temperature adjustment control>

  In the stop indoor unit liquid temperature adjustment control, in addition to the liquid side refrigerant temperature TL detected by each liquid side temperature sensor 36 of the operation indoor unit 5 in the operation indoor unit liquid temperature adjustment control, each liquid side temperature sensor of the stop indoor unit 5 The liquid side refrigerant temperature TL detected at 36 is taken in, and each liquid side refrigerant temperature TL of the operation indoor unit 5 is extracted from the taken in liquid side refrigerant temperature TL. Next, an average value TLave of the liquid side refrigerant temperature TL of each operating indoor unit 5 is obtained, and the second temperature difference ΔTb is obtained by subtracting the average value TLave from the liquid side refrigerant temperature TL of each stop indoor unit 5.

  Then, the opening degree of the expansion valve 24 corresponding to each stop indoor unit 5 is adjusted according to the obtained value of the second temperature difference ΔTb. Specifically, the pulse number PLS applied to the expansion valve 24 corresponding to each stop indoor unit 5 is a predetermined range (in this embodiment, 15 pulses in the present embodiment) including the initial pulse number PLS2 (25 pulses in the present embodiment). Between the first pulse and the second pulse) according to the value of the second temperature difference ΔTb. First, if the value of the second temperature difference ΔTb is equal to or greater than a predetermined first threshold temperature difference (8 ° C. in this embodiment), the second temperature difference ΔTb is calculated from the number of pulses PLS currently applied to the expansion valve 24. The number of pulses obtained by subtracting a value corresponding to the value is added to the expansion valve 24, and the opening degree of the expansion valve 24 is reduced. Thereby, since the refrigerant | coolant amount which flows through each stop indoor unit 5 reduces, the liquid side refrigerant | coolant temperature TL becomes low and approaches the average value TLave.

  On the other hand, if the value of the second temperature difference ΔTb is less than a predetermined second threshold temperature difference (for example, 2 ° C.) that is lower than the first threshold temperature difference, the number of pulses PLS currently applied to the expansion valve 24 is calculated. The number of pulses to which a value corresponding to the value of the second temperature difference ΔTb is added is added to the expansion valve 24, and the opening degree of the expansion valve 24 is increased. Thereby, since the refrigerant | coolant amount which flows through each stop indoor unit 5 increases, the liquid side refrigerant | coolant temperature TL becomes high and approaches average value TLave.

  By the way, when performing the above-described stop indoor unit liquid temperature adjustment control, for example, when some of the stop indoor units 5 are activated, if the heating load increases rapidly, the refrigerant in the refrigerant circuit 10 There is a risk that the circulation volume will be transiently insufficient. When the refrigerant circulation amount is transiently insufficient, the condensing pressure in the indoor heat exchanger 51 of the operation indoor unit 5 and the stop indoor unit 5 decreases transiently, resulting in the operation indoor unit 5 and The degree of refrigerant supercooling on the refrigerant outlet side of the indoor heat exchanger of the stop indoor unit 5 is reduced. At this time, if the opening degree of the expansion valve 24 corresponding to the stop indoor unit 5 is increased by the stop indoor unit liquid temperature adjustment control, the refrigerant in the gas-liquid two-phase state flows through the stop indoor unit 5 and the refrigerant flow noise is noticeable. The user may feel uncomfortable.

  Therefore, when the opening degree of the expansion valve 24 is increased by the stop indoor unit liquid temperature adjustment control, the refrigerant subcooling degree SC of the stop indoor unit 5 is calculated, and the refrigerant subcooling degree SC is a predetermined threshold refrigerant subcooling degree. If the value is smaller than (for example, 3 deg), the opening degree of the expansion valve 24 is not increased. Thereby, when there exists a possibility that a refrigerant | coolant may flow in a gas-liquid two-phase state, the refrigerant | coolant amount which flows through the stop indoor unit 5 does not increase.

  Next, processing related to the air conditioner 1 of the present embodiment will be described with reference to FIGS. FIG. 2 is a flowchart showing a main routine of processing performed by the CPU 210 of the outdoor unit control means 200, and shows a flow of processing executed by the CPU 210 when performing the heating operation. FIG. 3 is a flowchart showing a subroutine of processing performed by the CPU 210, and shows a flow of processing executed when the CPU 210 performs operation indoor unit fluid temperature adjustment control. FIG. 4 is a flowchart showing a subroutine of processing performed by the CPU 210, and shows a flow of processing executed when the CPU 210 performs stop indoor unit liquid temperature adjustment control.

  In the flowcharts shown in FIGS. 2 to 4, ST represents a process step, and the number following this represents a step number. Note that FIGS. 2 to 4 mainly describe processing related to the present invention, and other processing, for example, control according to operating conditions such as a set temperature and an air volume instructed by the user during heating operation. Explanation of general processing related to the air conditioner 1 is omitted.

  First, the flow of processing when the CPU 210 performs the heating operation in the air conditioner 1 will be described with reference to FIG. When the user operates a remote controller (not shown) of each indoor unit 5 to instruct the start of operation, CPU 210 determines whether the operation instructed by the user is a heating operation (ST1). If the operation instructed by the user is the heating operation (ST1-Yes), the CPU 210 executes a heating operation start process (ST2). Here, the heating operation start process means that the CPU 210 switches each port of the four-way valve 22 to the connection indicated by the solid line in FIG.

  CPU210 which finished the heating operation start process drives the compressor 21 and the outdoor fan 26 (ST3). Specifically, the CPU 210 performs drive control of the compressor 21 at a rotation speed corresponding to the heating capacity requested from each indoor unit 5, and the outdoor fan 26 has a rotation speed corresponding to the rotation speed of the compressor 21. Drive control is performed as follows.

  Next, the CPU 210 executes target discharge temperature control (ST4). Specifically, the CPU 210 first takes in the discharge pressure Hp detected by the high pressure sensor 31 and the suction pressure detected by the low pressure sensor 32 via the sensor input unit 240, and uses them to determine the condensation temperature and the evaporation temperature. Next, the CPU 210 calculates a target discharge temperature using the obtained condensing temperature and evaporation temperature and the rotation speed of the compressor 21. Then, the CPU 210 takes in the discharge temperature detected by the discharge temperature sensor 33 via the sensor input unit 240, and the opening degree of the expansion valve 24 corresponding to the operation indoor unit 5 so that the taken-in discharge temperature becomes the target discharge temperature. Adjust. The CPU 210 adds the aforementioned initial pulse number PLS1 to the expansion valve 24 corresponding to the operating indoor unit 5 at the start of the heating operation, and sets the opening degree of the expansion valve 24 corresponding to the operating indoor unit 5 to the initial pulse number PLS1. Set the corresponding opening. This initial pulse number PLS1 is selected by the air conditioning capability and the outside air temperature of each indoor unit 5 with a predetermined value (for example, 80 pulses) larger than the initial pulse number PLS2 applied to the stopped indoor unit 5 as a lower limit. Although not shown, each indoor unit 5 stores a table in which the initial pulse number PLS1 is determined corresponding to the outside air temperature.

  Next, the CPU 210 executes an operation indoor unit liquid temperature adjustment control that is a subroutine (ST5), and subsequently executes a stop indoor unit liquid temperature adjustment control that is a subroutine (ST6), and proceeds to ST7. .

  In ST7, CPU 210 determines whether or not there is an operation mode switching instruction from the user. 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 (ST7-Yes), the CPU 210 returns the process to ST1. When there is no operation mode switching instruction (ST7-No), the CPU 210 determines whether or not there is an operation stop instruction by the user (ST8). The operation stop instruction indicates that all the indoor units 5 stop the operation.

  If there is an operation stop instruction (ST8-Yes), the CPU 210 executes an operation stop process (ST9) and ends the process. In the operation stop process, the CPU 210 stops the compressor 21 and the outdoor fan 26 and fully closes each expansion valve 24. Moreover, CPU210 transmits the driving | operation stop signal to the effect of stopping a driving | operation via the communication part 230 with respect to indoor unit 5a-5c. Each indoor unit 5 that has received the operation stop signal stops the indoor fan 54.

  If there is no operation stop instruction in ST8 (ST8-No), CPU 210 determines whether or not the current operation is a heating operation (ST12). If the current operation is the heating operation (ST12-Yes), the CPU 210 returns the process to ST3. If the current operation is not the heating operation (ST12-No), that is, if the current operation is the cooling operation or the dehumidifying operation, the CPU 210 returns the process to ST11.

  If the operation instructed by the user in ST1 is not the heating operation (ST1-No), the CPU 210 executes a cooling / dehumidifying operation start process that is a start process of the cooling operation or the dehumidifying operation (ST10). 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. The CPU 210 drives the compressor 21 and the outdoor fan 27 at a predetermined rotational speed, fully opens each expansion valve 24, and controls the drive of the indoor fan 54 for each indoor unit 5 via the communication unit 230. The control of the cooling operation or the dehumidifying operation is started (ST11), and the process proceeds to ST7.

  Next, referring to FIG. 3, the flow of processing when performing the operation indoor unit liquid temperature adjustment control which is one subroutine of the present embodiment will be described.

  First, the CPU 210 takes in the liquid side refrigerant temperature TL of each indoor unit 5 via the communication unit 230 (ST21), and the maximum value from the liquid side refrigerant temperature TL of the operating indoor unit 5 among the taken in liquid side refrigerant temperature TL. The first temperature difference ΔTa is calculated by extracting TLmax and the minimum value TLmin and subtracting the minimum value TLmin from the maximum value TLmax (ST22).

  Next, CPU 210 determines whether or not calculated first temperature difference ΔTa is 6 ° C. or higher (ST23). When the first temperature difference ΔTa is 6 ° C. or more (ST23−Yes), the CPU 210 adds the maximum value PLSmax among the number of pulses PLS currently applied to the expansion valve 24 corresponding to the operating indoor unit 5. The number of pulses obtained by subtracting four pulses from the maximum value PLSmax is added to the expansion valve 24 for the valve 24, and the number of pulses obtained by adding four pulses to the minimum value PLSmin is added to the expansion valve 24. In addition to the valve 24 (ST24), the process is terminated.

  When the first temperature difference ΔTa is not 6 ° C. or more in ST23 (ST23-No), the CPU 210 determines whether or not the first temperature difference ΔTa is 4 ° C. or more and less than 6 ° C. (ST25). When the first temperature difference ΔTa is not less than 4 ° C. and less than 6 ° C. (ST25−Yes), the CPU 210 adds the maximum value PLSmax among the number of pulses PLS currently applied to the expansion valve 24 corresponding to the operating indoor unit 5. The number of pulses obtained by subtracting two pulses from the maximum value PLSmax is added to the expansion valve 24, and the number of pulses obtained by adding two pulses to the minimum value PLSmin is added to the expansion valve 24 adding the minimum value PLSmin. Is added to the expansion valve 24 (ST26), and the process is terminated.

  When the first temperature difference ΔTa is not 4 ° C. or more and less than 6 ° C. in ST25 (ST25-No), the CPU 210 determines whether or not the first temperature difference ΔTa is 2 ° C. or more and less than 4 ° C. (ST27). When the first temperature difference ΔTa is not less than 2 ° C. and less than 4 ° C. (ST27-Yes), the CPU 210 adds the maximum value PLSmax among the number of pulses PLS currently applied to the expansion valve 24 corresponding to the operating indoor unit 5. The number of pulses obtained by subtracting one pulse from the maximum value PLSmax is added to the expansion valve 24, and the number of pulses obtained by adding one pulse to the minimum value PLSmin is added to the expansion valve 24 adding the minimum value PLSmin. Is added to the expansion valve 24 (ST28), and the process is terminated. In ST27, when the first temperature difference ΔTa is not 2 ° C. or more and less than 4 ° C. (ST27-No), the CPU 210 ends the process without changing the opening degree of each expansion valve 24.

  Next, the flow of processing when performing stop indoor unit liquid temperature adjustment control, which is another subroutine of the present embodiment, will be described with reference to FIG. In this embodiment, the opening degree of the expansion valve 24 corresponding to the stop indoor unit 5 when performing the stop indoor unit liquid temperature adjustment control corresponds to the minimum value of the number of pulses PLS applied to the expansion valve 24: 15 pulses. It is assumed that the opening is adjusted to the maximum value: the opening corresponding to 100 pulses.

  First, the CPU 210 determines whether there is a stop indoor unit 5 (ST40). If there is no stop indoor unit 5 (ST40-Yes), CPU210 will complete | finish a process, without performing stop indoor unit liquid temperature adjustment control. If there is the stop indoor unit 5 (ST40-No), the CPU 210 reads the flag F stored in the storage unit 220, and determines whether or not the read flag F is 0 (ST41).

  This flag F is for determining whether or not the stop indoor unit liquid temperature adjustment control to be performed from now is performed for the first time after the start of the heating operation. If the flag F is 0, the stop indoor unit liquid temperature is not detected until the start of the heating operation. This indicates that the temperature adjustment control is to be executed. If the flag F is 1, it indicates that the stop indoor unit liquid temperature adjustment control has already been executed. The flag F is reset (set to 0) by the CPU 210 when the stopped indoor units 5 are eliminated, that is, when all the indoor units 5 are operated.

  If flag F is not 0 in ST41 (ST41-No), CPU 210 advances the process to ST43. If the flag F is 0 (ST41-Yes), the CPU 210 adds the initial pulse number PLS2 to the expansion valve 24 corresponding to the stop indoor unit 5 (ST42), and sets the initial opening of each expansion valve 24 when the heating operation is stopped. Then, the process proceeds to ST43. The initial pulse number PLS2 applied to the stop indoor unit 5 is smaller than the initial pulse number PLS1 applied to the operation indoor unit 5 described above, for example, 25 pulses.

  Next, the CPU 210 takes in the liquid side refrigerant temperature TL of each indoor unit 5 via the communication unit 230 (ST43), and uses the liquid side refrigerant temperature TL of the operating indoor unit 5 among the taken-in liquid side refrigerant temperature TL. Then, an average value TLave is obtained, and the second temperature difference ΔTb is calculated by subtracting the average value TLave from the liquid side refrigerant temperature TL of the stop indoor unit 5 (ST44).

  Next, CPU 210 determines whether or not the calculated second temperature difference ΔTb is equal to or higher than 15 ° C. (ST45). When the second temperature difference ΔTb is 15 ° C. or more (ST45−Yes), the CPU 210 subtracts 3 pulses from the number of pulses PLS currently applied to the expansion valve 24 of the stop indoor unit 5 (ST46), and performs the process in ST49. Proceed.

  When the second temperature difference ΔTb is not 15 ° C. or more in ST45 (ST45-No), the CPU 210 determines whether the second temperature difference ΔTb is 8 ° C. (first threshold temperature difference described above) or more and less than 15 ° C. Judgment is made (ST47). When the second temperature difference ΔTb is not less than 8 ° C. and less than 15 ° C. (ST47-Yes), the CPU 210 subtracts one pulse from the number of pulses PLS currently applied to the expansion valve 24 of the stop indoor unit 5 (ST48), ST49. Proceed with the process.

  In ST49, the CPU 210 determines whether or not the pulse number PLS obtained in the processing of ST46 and ST48 is less than 15 pulses that is the minimum value of the pulse number PLS applied to the stop indoor unit 5. If the obtained pulse number PLS is less than 15 pulses (ST49-Yes), CPU 210 adds 15 pulses to expansion valve 24 corresponding to stop indoor unit 5 (ST50), and proceeds to ST63. If the obtained pulse number PLS is not less than 15 pulses (ST49-No), the CPU 210 adds the pulse number PLS obtained in ST46 or ST48 to the expansion valve 24 corresponding to the stop indoor unit 5 (ST51), and then to ST63. Proceed with the process.

  On the other hand, when the second temperature difference ΔTb is not 8 ° C. or more and less than 15 ° C. in ST47 (ST47-No), the CPU 210 takes in the discharge pressure Hp detected by the high pressure sensor 31 via the sensor input unit 240 and takes it in. The high pressure saturation temperature Thp is calculated using the discharge pressure Hp (ST52), and the liquid side refrigerant temperature TL taken in ST43 is subtracted from the calculated high pressure saturation temperature Thp to calculate the refrigerant subcooling degree SC in the stop indoor unit 5 ( ST53).

  Next, CPU 210 determines whether or not second temperature difference ΔTb calculated in ST44 is less than 0 ° C. (ST54). If the second temperature difference ΔTb is not less than 0 ° C. (ST54-No), the CPU 210 advances the process to ST57. When the second temperature difference ΔTb is less than 0 ° C. (ST54−Yes), the CPU 210 determines whether or not the refrigerant supercooling degree SC calculated in ST53 is less than 3 deg (ST55).

  When the refrigerant supercooling degree SC is less than 3 degrees (ST55-Yes), the CPU 210 advances the process to ST63. When the refrigerant supercooling degree SC is not less than 3 degrees (ST55-No), the CPU 210 adds three pulses to the pulse number PLS currently applied to the expansion valve 24 of the stop indoor unit 5 (ST56), and proceeds to ST60.

  In ST57, the CPU 210 determines whether or not the second temperature difference ΔTb is not less than 0 ° C. and less than 2 ° C. (second threshold temperature difference described above) (ST57). If the second temperature difference ΔTb is not greater than 0 ° C. and less than 2 ° C. (ST57-No), the CPU 210 advances the process to ST63. When the second temperature difference ΔTb is not less than 0 ° C. and less than 2 ° C. (ST57-Yes), the CPU 210 determines whether or not the refrigerant supercooling degree SC calculated in ST53 is less than 3 deg (ST58).

  When the refrigerant supercooling degree SC is less than 3 degrees (ST58-Yes), the CPU 210 advances the process to ST63. When the refrigerant supercooling degree SC is not less than 3 degrees (ST58-No), the CPU 210 adds one pulse to the pulse number PLS currently applied to the expansion valve 24 of the stop indoor unit 5 (ST59), and proceeds to ST60.

  In ST60, the CPU 210 determines whether or not the pulse number PLS obtained in the processing of ST56 and ST59 is larger than 100 pulses that is the maximum value of the pulse number PLS applied to the stop indoor unit 5. When the obtained pulse number PLS is larger than 100 pulses (ST60-Yes), the CPU 210 adds 100 pulses to the expansion valve 24 corresponding to the stop indoor unit 5 (ST61), and proceeds to ST63. If the obtained pulse number PLS is 100 pulses or less (ST60-No), the CPU 210 adds the pulse number PLS obtained in ST56 or ST59 to the expansion valve 24 corresponding to the stop indoor unit 5 (ST62), and then to ST63. Proceed with the process.

  In ST63, the CPU 210 stores the flag F as 1 in the storage unit 220, and ends the stop indoor unit liquid temperature adjustment control.

  In the embodiment described above, the temperature differences used in the determination of the magnitude of the first temperature difference ΔTa in ST23, ST25 and ST27 in the flowchart of the operation indoor unit liquid temperature adjustment control shown in FIG. 3 and ST24, ST26 and ST28. The number of pulses increased and decreased, the temperature differences used to determine the magnitude of the second temperature difference ΔTb in ST45, ST47, ST54, and ST57 in the flowchart of the stop indoor unit fluid temperature adjustment control shown in FIG. 4 and ST46, ST48, and ST56. The number of pulses increased or decreased in ST59 and the minimum and maximum values of the pulse PLS applied to the expansion valve 24 corresponding to the stop indoor unit 5 are values unique to the present embodiment, and these values are obtained by conducting a test or the like in advance. Is. Accordingly, each of the above numerical values can be appropriately selected depending on the configuration of the air conditioner 1 (the number of indoor units 5 to be connected and the capacity thereof, the pipe length of the refrigerant circuit 10, etc.).

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Outdoor unit 5 Indoor unit 21 Compressor 22 Four-way valve 23 Outdoor heat exchanger 24 Expansion valve 51 Indoor heat exchanger 200 Outdoor unit control part 210 CPU
220 Storage unit 240 Sensor input unit TL Liquid side refrigerant temperature TLmax Maximum value of liquid side refrigerant temperature of operating indoor unit TLmin Minimum value of liquid side refrigerant temperature of operating indoor unit TLave Average value of liquid side refrigerant temperature of operating indoor unit ΔTa No. 1 Temperature difference ΔTb Second temperature difference Thp High pressure saturation temperature Hp Discharge pressure PLS Number of pulses applied to expansion valve PLS1 Initial number of pulses applied to expansion valve of operation indoor unit PLS2 Initial number of pulses applied to expansion valve of stop indoor unit PLSmax Operation indoor unit Maximum number of pulses applied to expansion valve of PLSmin Minimum value of pulses applied to expansion valve of indoor unit

Claims (2)

An air conditioner having a refrigerant circuit in which an outdoor unit, a plurality of indoor units, and the outdoor unit and the plurality of indoor units are connected by a refrigerant pipe,
The plurality of indoor units have indoor heat exchangers,
The outdoor unit includes a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve provided in the same number as the number of the indoor units, and the same number as the number of the indoor units. A liquid side temperature detecting means for detecting a liquid side refrigerant temperature which is a temperature of a refrigerant flowing out of the indoor heat exchanger of the machine,
When the operation indoor unit and the stop indoor unit are mixed when the air conditioner is performing the heating operation,
While performing the target discharge temperature control for adjusting the opening of the expansion valve corresponding to the operating indoor unit so that the discharge temperature that is the refrigerant temperature discharged from the compressor becomes the target discharge temperature,
Executing the stop indoor unit liquid temperature adjustment control for adjusting the opening of the expansion valve corresponding to the stop indoor unit so that the liquid side refrigerant temperature detected by the liquid side temperature detection means of the stop indoor unit becomes a predetermined temperature;
When increasing the opening degree of the expansion valve corresponding to the stopped indoor unit in the stopped indoor unit liquid temperature adjustment control, the refrigerant supercooling degree on the refrigerant outlet side of the indoor heat exchanger of the stopped indoor unit is determined in advance. Control means for increasing the opening of the expansion valve corresponding to the stop indoor unit larger than the threshold refrigerant supercooling degree,
An air conditioner characterized by that. The predetermined temperature is an average value of the liquid side refrigerant temperature detected by the liquid side temperature detecting means of the operating indoor unit.
The air conditioner according to claim 1.

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