JP2017142017A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner capable of accurately deciding whether an indoor unit which cannot sufficiently display heating capacity during heating operation exists or not.SOLUTION: During heating operation, a CPU inputs condensing pressure Ph detected by a discharge pressure sensor and inputs liquid pipe coolant pressure Pm from respective indoor units via a communication part. Then, the CPU finds out a pressure difference ΔP by reducing the liquid pipe coolant pressure Pm from the inputted condensing pressure Ph. Then, the CPU decides whether the found pressure difference ΔP is smaller than a threshold pressure difference ΔPs or not. When the pressure difference ΔP is smaller than the threshold pressure difference ΔPs, the CPU executes non-heating dissolving control.SELECTED DRAWING: Figure 3

Description

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

  Conventionally, in an air conditioner in which a plurality of indoor units are connected to at least one outdoor unit by liquid pipes and gas pipes, each indoor unit is installed with a height difference, and the outdoor unit is positioned higher than each indoor unit. It may be installed in. When the air conditioner thus installed performs a heating operation, there is a possibility that sufficient heating capacity may not be obtained with an indoor unit installed at a low position for the reason described below.

  In the heating operation, it is necessary to flow the liquid refrigerant condensed in the indoor heat exchanger of each indoor unit and flowing into the liquid pipe toward the outdoor unit installed at a position higher than each indoor unit against gravity. For this reason, the pressure of the liquid refrigerant (hereinafter referred to as liquid pipe refrigerant pressure) on the downstream side (outdoor unit side) of the indoor expansion valve of the indoor unit installed at the low position is the room of the indoor unit installed at the high position. It becomes higher than the liquid pipe refrigerant pressure on the downstream side of the expansion valve.

  Therefore, the indoor unit installed at a position where the pressure difference between the condensation pressure corresponding to the refrigerant pressure upstream of the indoor expansion valve (the indoor heat exchanger side) of the indoor unit installed at the low position and the liquid pipe refrigerant pressure is high. It becomes smaller than the pressure difference between the condensation pressure and the liquid refrigerant pressure. The smaller the pressure difference between the condensation pressure and the liquid pipe refrigerant pressure, the smaller the amount of refrigerant flowing through the indoor expansion valve, so that more refrigerant flows through the indoor unit installed at a higher position, while the indoor space installed at a lower position. There is a risk that the amount of refrigerant flowing into the machine will decrease and sufficient indoor heating capacity will not be obtained.

  Therefore, when performing heating operation with the air conditioner installed in the state described above, it is as accurately as possible ascertained whether or not the heating capacity is exhibited by the indoor unit installed at a low position, and the heating capacity is If it is found that the indoor unit is not fully utilized, it is necessary to perform control (hereinafter referred to as non-heating cancellation control) for improving the heating capacity of the indoor unit.

  In the multi-type air conditioner described in Patent Literature 1, the opening degree of each indoor expansion valve is adjusted so that the degree of refrigerant supercooling in each indoor unit becomes a target value during heating operation. In this multi-air conditioner, if multiple indoor units are installed with a height difference, if there is an indoor unit whose refrigerant supercooling level is higher than the target value after a certain period of time has elapsed since the start of heating operation Therefore, it is determined that the liquid refrigerant has accumulated in the indoor unit and sufficient heating capacity has not been exhibited, and non-heating cancellation control is performed.

JP 2011-158118 A

  By the way, when the air conditioner is performing the heating operation, when the outside air temperature is low and the condensation temperature of the indoor unit is low, each indoor unit is installed with a difference in height, and the outdoor unit is more than the indoor unit. Even in the case of being installed at a high position, the refrigerant subcooling degree in each indoor unit may be all the target value.

  For example, as shown in FIG. 2, an indoor unit is installed on each floor of a 10-story building, and a heating operation is performed with an air conditioner in which an outdoor unit is installed on the roof. There is an indoor unit in which the high-pressure saturation temperature corresponding to the condensing temperature of the unit is 30 ° C., the outside air temperature is −20 ° C., the heating operation set temperature is 24 ° C., and the refrigerant supercooling degree is 15 degrees or more at this time In this case, it is determined that the indoor unit has not sufficiently exhibited the heating capacity. In this case, as described in FIG. 2, the refrigerant subcooling degree in each indoor unit (in FIG. 2, the refrigerant subcooling degree is represented by SCa, SCb, and SCc) is less than 15 deg. It is judged that the indoor unit has sufficient heating capacity.

  However, actually, in the indoor unit installed on the first floor, the heat exchange outlet temperature, which is the refrigerant temperature flowing out from the indoor heat exchanger, and the suction temperature, which is the temperature of the indoor air sucked into the indoor unit, are the same 20 ° C. ing. This is because liquid refrigerant accumulates in the indoor unit installed on the first floor, and the refrigerant temperature on the refrigerant outlet side of the indoor heat exchanger becomes familiar with the indoor air temperature. This indicates the possibility that is not fully demonstrated.

  As described above, in order to determine whether the indoor unit has heating capacity based on whether or not the refrigerant supercooling degree has reached the target value, the indoor unit installed at a low position is actually heated. Even when the ability is not fully exhibited, there is a possibility that it is erroneously determined that the heating ability is exhibited.

  The present invention solves the above-described problems, and an object thereof is to provide an air conditioner that can accurately determine whether there is an indoor unit that does not sufficiently exhibit the heating capacity during heating operation. To do.

  In order to solve the above problems, an air conditioner according to the present invention condenses an outdoor unit having a compressor and a condensing pressure detecting means for detecting condensing pressure, an indoor heat exchanger, an indoor expansion valve, and an indoor heat exchanger. Having a plurality of indoor units having liquid pipe pressure detecting means for detecting a liquid pipe refrigerant pressure that is a pressure of the refrigerant flowing out from the indoor expansion valve when functioning as an outdoor unit, and the outdoor unit being a plurality of indoor units In addition to being installed at a higher position, there are differences in the installation locations of the plurality of indoor units. Then, when the indoor heat exchanger functions as a condenser, the pressure difference between the condensation pressure and the liquid refrigerant pressure is calculated for each of the plurality of indoor units, and this pressure difference is a predetermined threshold pressure difference. If it is smaller, it is determined that the indoor unit is not capable of exerting heating capability.

  According to the air conditioner of the present invention configured as described above, it is possible to accurately determine whether there is an indoor unit that does not sufficiently exhibit the heating capacity during the heating operation.

It is explanatory drawing of the air conditioning apparatus in embodiment of this invention, (A) is a refrigerant circuit figure, (B) is a block diagram of an outdoor unit control means and an indoor unit control means. It is drawing which shows the installation state of an indoor unit and the outdoor unit in the embodiment of the present invention, and the operation state of each indoor unit. It is a flowchart explaining the process in the outdoor unit control part 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, 10 indoor units installed on each floor of a building are connected in parallel to one outdoor unit installed on the roof of a building, and cooling operation or heating operation can be performed simultaneously on all indoor units An air conditioning apparatus 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. 1 (A) and FIG. 2, the air conditioner 1 in the present embodiment is installed on one floor of a 10-story building, and on each floor of the building. The unit 2 includes ten indoor units connected in parallel by a liquid pipe 8 and a gas pipe 9. Specifically, the liquid pipe 8 has one end branched to the closing valve 25 of the outdoor unit 2 and the other end branched to a liquid pipe connecting portion of each indoor unit (in the indoor units 5a to 5c, the liquid pipe connecting portions 53a to 53c). Are connected to each other. Further, the gas pipe 9 has one end branched to the closing valve 26 of the outdoor unit 2 and the other end branched to the gas pipe connecting portion of each indoor unit (in the indoor units 5a to 5c, the gas pipe connecting portions 54a to 54c) Each is connected. The refrigerant circuit 100 of the air conditioner 1 is configured as described above.
In FIG. 1A and FIG. 2, only the indoor unit 5a installed on the 10th floor, the indoor unit 5b installed on the 5th floor, and the indoor unit 5c installed on the 1st floor among the 10 indoor units. Show.

  First, the outdoor unit 2 will be described. The outdoor unit 2 includes a compressor 21, a four-way valve 22, an outdoor heat exchanger 23, an outdoor expansion valve 24, a closing valve 25 to which one end of the liquid pipe 8 is connected, and one end of the gas pipe 9. And a close-up valve 26, an accumulator 28 as a refrigerant reservoir, and an outdoor fan 27. These devices other than the outdoor fan 27 are connected to each other through refrigerant pipes described in detail below to constitute an outdoor unit refrigerant circuit 20 that forms part of the refrigerant circuit 100.

  The compressor 21 is a variable capacity compressor that can vary its operating capacity by being driven by a motor (not shown) whose rotation speed is controlled by an inverter. The refrigerant discharge side of the compressor 21 is connected to a port a of a four-way valve 22 described later by a discharge pipe 41, and the refrigerant suction side of the compressor 21 is connected to the refrigerant outflow side of the accumulator 28 by a suction pipe 42. Has been.

  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 41 as described above. The port b is connected to one refrigerant inlet / outlet of the outdoor heat exchanger 23 by a refrigerant pipe 43. The port c is connected to the refrigerant inflow side of the accumulator 28 by a refrigerant pipe 46. The port d is connected to the closing valve 26 by an outdoor unit gas pipe 45.

  The outdoor heat exchanger 23 exchanges heat between the refrigerant and outside air taken into the outdoor unit 2 by rotation of an outdoor fan 27 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 43, and the other refrigerant inlet / outlet is connected to the closing valve 25 by the outdoor unit liquid pipe 44.

  The outdoor expansion valve 24 is provided in the outdoor unit liquid pipe 44. The outdoor expansion valve 24 is an electronic expansion valve, and the amount of refrigerant flowing into the outdoor heat exchanger 23 or the amount of refrigerant flowing out of the outdoor heat exchanger 23 is adjusted by adjusting the opening thereof. The opening degree of the outdoor expansion valve 24 is fully opened when the air conditioner 1 is performing a cooling operation. In addition, when the air conditioner 1 is performing a heating operation, the opening temperature is controlled according to the discharge temperature of the compressor 21 detected by a discharge temperature sensor 33 described later, so that the discharge temperature has a performance upper limit value. I do not exceed it.

  The outdoor fan 27 is formed of a resin material and is disposed in the vicinity of the outdoor heat exchanger 23. The outdoor fan 27 is rotated by a fan motor (not shown) to take outside air from a suction port (not shown) into the outdoor unit 2, and the outdoor air heat exchanged with the refrigerant in the outdoor heat exchanger 23 is sent from the blower outlet (not shown) to the outdoor unit 2. To the outside.

  As described above, the accumulator 28 has the refrigerant inflow side connected to the port c of the four-way valve 22 via the refrigerant pipe 46 and the refrigerant outflow side connected to the refrigerant intake side of the compressor 21 via the suction pipe 42. The accumulator 28 separates the refrigerant flowing into the accumulator 28 from the refrigerant pipe 46 into a gas refrigerant and a liquid refrigerant, and causes the compressor 21 to suck only the gas refrigerant.

  In addition to the configuration described above, the outdoor unit 2 is provided with various sensors. As shown in FIG. 1 (A), the discharge pipe 41 includes a discharge pressure sensor 31 (corresponding to the condensing pressure detection means of the present invention) that detects the discharge pressure that is the pressure of the refrigerant discharged from the compressor 21, and A discharge temperature sensor 33 that detects the temperature of the refrigerant discharged from the compressor 21 is provided. Near the refrigerant inlet of the accumulator 28 in the refrigerant pipe 46, a suction 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. And are provided.

  Between the outdoor heat exchanger 23 and the outdoor expansion valve 24 in the outdoor unit liquid pipe 44, the temperature of the refrigerant flowing into the outdoor heat exchanger 23 or the temperature of the refrigerant flowing out of the outdoor heat exchanger 23 is detected. A heat exchanger temperature sensor 35 is provided. An outdoor air temperature sensor 36 that detects the temperature of the outside air that flows into the outdoor unit 2, that is, the outside air temperature, is provided near the suction port (not shown) of the outdoor unit 2.

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

  The storage unit 220 includes a ROM and a RAM, and stores a control program for the outdoor unit 2, detection values corresponding to detection signals from various sensors, control states of the compressor 21 and the outdoor fan 27, and the like. The communication unit 230 is an interface that performs communication with the indoor units 5a to 5c. 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. In addition, the CPU 210 takes in control signals transmitted from the indoor units 5 a to 5 c via the communication unit 230. The CPU 210 performs drive control of the compressor 21 and the outdoor fan 27 based on the detection results and control signals taken in. In addition, the CPU 210 performs switching control of the four-way valve 22 based on the detection results and control signals taken in. Furthermore, the CPU 210 adjusts the opening degree of the outdoor expansion valve 24 based on the acquired detection result and control signal.

  Next, 10 indoor units will be described. Since all ten indoor units have the same configuration, the following description will be made on the three indoor units 5a to 5c shown in FIG. The three indoor units 5a to 5c are branched into indoor heat exchangers 51a to 51c, indoor expansion valves 52a to 52c, and liquid pipe connection portions 53a to 53c to which the other ends of the branched liquid pipes 8 are connected. Gas pipe connection parts 54a to 54c to which the other end of the gas pipe 9 is connected and indoor fans 55a to 55c are provided. And these each apparatus except indoor fan 55a-55c is mutually connected by each refrigerant | coolant piping explained in full detail below, and comprises the indoor unit refrigerant circuit 50a-50c which makes a part of refrigerant circuit 100. FIG.

  Next, the configuration of the indoor units 5a to 5c will be described in detail. In the following description, the indoor unit 5a will be described as an example, and detailed description will be omitted for the other indoor units 5b and 5c. Moreover, in FIG. 1, what changed the end of the number provided to the component apparatus of the indoor unit 5a from a to b and c becomes the component apparatus of the indoor units 5b and 5c corresponding to the component apparatus of the outdoor unit 5a. .

The indoor heat exchanger 51a exchanges heat between indoor air taken into the indoor unit 5a from a suction port (not shown) by rotation of a refrigerant and an indoor fan 55a described later, and one refrigerant inlet / outlet is a liquid pipe connection portion. 53a is connected by an indoor unit liquid pipe 71a, and the other refrigerant inlet / outlet is connected to the gas pipe connecting part 54a by an indoor unit gas pipe 72a. The indoor heat exchanger 51a functions as an evaporator when the indoor unit 5a performs a cooling operation, and functions as a condenser when the indoor unit 5a performs a heating operation.
Note that the refrigerant pipes of the liquid pipe connecting part 53a and the gas pipe connecting part 54a are connected by welding, flare nuts, or the like.

  The indoor expansion valve 52a is provided in the indoor unit liquid pipe 71a. The indoor expansion valve 52a is an electronic expansion valve, and when the indoor heat exchanger 51a functions as an evaporator, that is, when the indoor unit 5a performs a cooling operation, the opening degree of the indoor expansion valve 52a depends on the refrigerant outlet (gas gas) of the indoor heat exchanger 51a. The refrigerant superheat degree at the pipe connecting portion 54a side) is adjusted to be the target refrigerant superheat degree. Further, when the indoor heat exchanger 51a functions as a condenser, that is, when the indoor unit 5a performs a heating operation, the opening of the indoor expansion valve 52a is the refrigerant outlet (liquid pipe connection portion) of the indoor heat exchanger 51a. 53a side) is adjusted so that the refrigerant subcooling degree becomes the target refrigerant subcooling degree. Here, the target refrigerant superheat degree and the target refrigerant subcool degree are the refrigerant superheat degree and the refrigerant subcool degree necessary for exhibiting sufficient cooling capacity or heating capacity in the indoor unit 5a.

  The indoor fan 55a is formed of a resin material and is disposed in the vicinity of the indoor heat exchanger 51a. The indoor fan 55a is rotated by a fan motor (not shown) to take indoor air from the suction port (not shown) into the indoor unit 5a, and the indoor air exchanged with the refrigerant in the indoor heat exchanger 51a from the blower outlet (not shown). Supply indoors.

  In addition to the configuration described above, the indoor unit 5a is provided with various sensors. Between the indoor heat exchanger 51a and the indoor expansion valve 52a in the indoor unit liquid pipe 71a, a liquid side temperature sensor 61a that detects the temperature of the refrigerant flowing into or out of the indoor heat exchanger 51a. Is provided. The indoor unit gas pipe 72a is provided with a gas side temperature sensor 62a that detects the temperature of the refrigerant flowing out of the indoor heat exchanger 51a or flowing into the indoor heat exchanger 51a. Near the suction port (not shown) of the indoor unit 5a, there is provided a suction temperature sensor 63a which is a suction temperature detecting means for detecting the temperature of the indoor air flowing into the indoor unit 5a, that is, the suction temperature. And between the indoor expansion valve 52a and the liquid side connection part 53a in the indoor unit liquid pipe 71a, a liquid pipe refrigerant pressure that is the pressure of the refrigerant flowing into or out of the indoor expansion valve 52a is detected. A liquid pipe pressure sensor 64a (corresponding to the liquid pipe pressure detecting means of the present invention) is provided.

  The indoor unit 5a includes an indoor unit control means 500a. The indoor unit control means 500a is mounted on a control board stored in an electrical component box (not shown) of the indoor unit 5a. As shown in FIG. 1B, a CPU 510a, a storage unit 520a, a communication unit 530a, And a sensor input unit 540a.

  The storage unit 520a includes a ROM and a RAM, and stores a control program for the indoor unit 5a, detection values corresponding to detection signals from various sensors, setting information regarding air conditioning operation by the user, and the like. The communication unit 530a is an interface that communicates with the outdoor unit 2 and the other indoor units 5b and 5c. The sensor input unit 540a captures detection results from various sensors of the indoor unit 5a and outputs them to the CPU 510a.

The CPU 510a takes in the detection result of each sensor of the indoor unit 5a described above via the sensor input unit 540a. Further, the CPU 510a takes in a signal including operation information set by operating a remote controller (not shown), a timer operation setting, and the like via a remote control light receiving unit (not shown). Further, the CPU 510a transmits a control signal including an operation start / stop signal and operation information (set temperature, indoor temperature, etc.) to the outdoor unit 2 via the communication unit 530a, and discharge pressure detected by the outdoor unit 2. A control signal including such information is received from the outdoor unit 2 via the communication unit 530a. The CPU 510a performs the opening degree adjustment of the indoor expansion valve 52a and the drive control of the indoor fan 55a based on the acquired detection result and the signal transmitted from the remote controller and the outdoor unit 2.
The outdoor unit control unit 200 and the indoor unit control units 500a to 500c described above constitute the control unit of the present invention.

  The air conditioning apparatus 1 described above is installed in a building 600 shown in FIG. Specifically, the outdoor unit 2 is arranged on the roof (RF), the indoor unit 5a is installed on the 10th floor, the indoor unit 5b is installed on the 5th floor, and the indoor unit 5c is installed on the 1st floor. And the outdoor unit 2 and the indoor units 5a-5c are mutually connected by the liquid pipe 8 and the gas pipe 9 which were mentioned above, and these liquid pipe 8 and the gas pipe 9 are in the wall surface of the building 600 which is not shown in figure. Or buried in the ceiling. In FIG. 2, the height difference between the indoor unit 5a installed on the top floor (10th floor) and the indoor unit 5c installed on the bottom floor (1st floor) is represented by H. Moreover, although illustration is abbreviate | omitted, indoor units other than the indoor units 5a-5c shown in FIG. 2 are installed in each floor of the 2nd floor-the 4th floor and the 6th floor-the 9th floor.

  Next, the flow of the refrigerant and the operation of each part in the refrigerant circuit 100 during the air conditioning operation of the air-conditioning apparatus 1 in the present embodiment will be described with reference to FIG. In addition, in the following description, the case where the air conditioning apparatus 1 performs heating operation will be described, and detailed description will be omitted for the case where cooling / defrosting operation is performed. Moreover, the arrow in FIG. 1 (A) has shown the flow of the refrigerant | coolant at the time of heating operation. The refrigerant flow and the operation of each part in each indoor unit are described only for the three indoor units 5a to 5c shown in FIG. 1A and FIG. 2, but the same applies to the other indoor units. is there.

  As shown in FIG. 1A, when the air conditioner 1 performs the heating operation, the CPU 210 of the outdoor unit control means 200 is a state where the four-way valve 22 is indicated by a solid line, that is, the port a and the port d of the four-way valve 22. Are switched so as to communicate with each other, and port b and port c communicate with each other. Thereby, the refrigerant circuit 100 becomes a heating cycle in which the outdoor heat exchanger 23 functions as an evaporator and the indoor heat exchangers 51a to 51c function as condensers.

  The high-pressure refrigerant discharged from the compressor 21 flows through the discharge pipe 41 and flows into the four-way valve 22, and from the four-way valve 22 to the outdoor unit gas pipe 45, the closing valve 26, the gas pipe 9, and the gas pipe connection portions 54 a to 54 c. In this order and flow into the indoor units 5a to 5c. The refrigerant that has flowed into the indoor units 5a to 5c flows through the indoor unit gas pipes 72a to 72c, flows into the indoor heat exchangers 51a to 51c, and is taken into the indoor units 5a to 5c by the rotation of the indoor fans 55a to 55c. Heat exchanges with room air and condenses. As described above, the indoor heat exchangers 51a to 51c function as condensers, and the indoor air that has exchanged heat with the refrigerant in the indoor heat exchangers 51a to 51c is blown into the room from a blowout port (not shown), thereby The room where the machines 5a to 5c are installed is heated.

  The refrigerant flowing out of the indoor heat exchangers 51a to 51c flows through the indoor unit liquid pipes 71a to 71c, passes through the indoor expansion valves 52a to 52c, and is decompressed. The decompressed refrigerant flows through the indoor unit liquid pipes 71 a to 71 c and the liquid pipe connection portions 53 a to 53 c and flows into the liquid pipe 8.

  The refrigerant flowing through the liquid pipe 8 flows into the outdoor unit 2 through the closing valve 25. The refrigerant flowing into the outdoor unit 2 flows through the outdoor unit liquid pipe 44 and is further reduced in pressure when passing through the outdoor expansion valve 24 having an opening degree corresponding to the discharge temperature of the compressor 21 detected by the discharge temperature sensor 33. The The refrigerant flowing into the outdoor heat exchanger 23 from the outdoor unit liquid pipe 44 evaporates by exchanging heat with the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 27. The refrigerant flowing out of the outdoor heat exchanger 23 flows in the order of the refrigerant pipe 43, the four-way valve 22, the refrigerant pipe 46, the accumulator 28, and the suction pipe 42, and is sucked into the compressor 21 and compressed again.

  When the air conditioner 1 performs the cooling / defrosting operation, the CPU 210 indicates that 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 communicate with each other, Switch so as to communicate with port d. Thereby, the refrigerant circuit 100 becomes a cooling cycle in which the outdoor heat exchanger 23 functions as a condenser and the indoor heat exchanger of each indoor unit functions as an evaporator.

  Next, with reference to FIGS. 1 to 3, the operation, action, and effect of the refrigerant circuit according to the present invention in the air-conditioning apparatus 1 of the present embodiment will be described. In addition, the liquid side temperature sensors 61a-61c when the indoor heat exchangers 51a-51c function as a condenser are sensors which detect the heat exchange outlet temperature To mentioned later.

  As shown in FIG. 2, in the air conditioner 1 of the present embodiment, the outdoor unit 2 is installed on the roof of the building 600 and each indoor unit is installed on each floor of the building 600. In other words, the outdoor unit 2 is installed at a position higher than each indoor unit, and the installation location of the indoor unit 5a installed on the 10th floor and the indoor unit 5c installed on the first floor has a height difference H. It has become. In this case, when the air conditioning apparatus 1 performs a heating operation, there are the following problems.

  In the heating operation, the gas refrigerant discharged from the compressor 21 flows from the discharge pipe 41 through the four-way valve 22 through the outdoor unit gas pipe 45, flows out of the outdoor unit 2, and flows into the indoor heat exchanger of each indoor unit. And condense. At this time, since the outdoor unit 2 is installed at a position higher than each indoor unit, the liquid refrigerant condensed in each indoor heat exchanger and flowing into the liquid pipe 8 is directed toward the outdoor unit 2 against gravity. It will flow through the tube 8.

  Therefore, the liquid refrigerant pressure, which is the pressure of the liquid refrigerant on the downstream side (outdoor unit 2 side) of the indoor expansion valve 52c of the indoor unit 5c installed on the first floor, is that of the indoor unit installed on the other floor. Since it becomes higher than the liquid pipe refrigerant pressure, the pressure difference between the condensing pressure, which is the refrigerant pressure upstream of the indoor expansion valve 52c (the indoor heat exchanger 51c side) of the indoor unit 5c, and the liquid pipe refrigerant pressure is another indoor unit. It becomes smaller than the pressure difference between the condensation pressure and the liquid refrigerant pressure.

  In the state of the refrigerant circuit 100 as described above, the smaller the pressure difference between the condensation pressure and the liquid pipe refrigerant pressure, the smaller the amount of refrigerant flowing through the indoor expansion valve. Accordingly, the amount of refrigerant flowing through the indoor unit 5c installed on the first floor is smaller than the amount of refrigerant flowing through other indoor units. This becomes more significant as the height difference H between the indoor unit 5c installed on the first floor (lowest position) and the indoor unit 5a installed on the 10th floor (highest position) increases. Is increased (for example, 50 m), the liquid refrigerant flowing out from the indoor unit 5 c to the liquid pipe 8 may not flow toward the outdoor unit 2, and the liquid refrigerant may stay below the liquid pipe 8. If the liquid refrigerant stays below the liquid pipe 8, even if the indoor expansion valve 5c is fully opened, the refrigerant does not flow into the indoor unit 5c, and the indoor unit 5c may not be able to exhibit the heating capability.

  Then, like the air conditioning apparatus 1 of this embodiment, the outdoor unit 2 is installed on the roof, each indoor unit is installed at a position lower than the outdoor unit 2, and there is a height difference in the installation position of each indoor unit. In some cases, it is possible to grasp as accurately as possible whether the indoor unit installed at a low position during heating operation is demonstrating the heating capability, and if it is found that the heating capability is not sufficiently exhibited, It is necessary to perform non-heating cancellation control to improve the heating capacity with a machine.

  In the conventional air conditioner, the refrigerant subcooling degree in each indoor unit is calculated after a certain time has elapsed from the start of the heating operation, and the indoor unit does not reach a predetermined target value, more specifically, the heating capacity is It was determined that sufficient heating capacity was not obtained with an indoor unit larger than the upper limit value of the refrigerant supercooling degree that is known in advance (hereinafter referred to as the performance compensation upper limit value). However, in this method, when the outdoor air temperature is low and the condensation temperature of each indoor heat exchanger is low, the refrigerant subcooling degree in each indoor unit may be less than the performance compensation upper limit value, which is low. Even if the indoor unit installed at the position does not actually have sufficient heating capacity, there is a risk of misjudging that the heating capacity has been achieved.

  A state in which it is erroneously determined that the heating capacity can be exhibited in all the indoor units during the heating operation will be described with reference to the example shown in FIG. In the following description, the pressure detected by the discharge pressure sensor 31 and corresponding to the condensation pressure of the indoor heat exchangers 51a to 51c is Ph, and the discharge pressure sensor corresponds to the condensation temperature of the indoor heat exchangers 51a to 51c. The high-pressure saturation temperature obtained using the pressure detected at 31 (= condensation pressure Ph) is Ths.

  The temperature of the refrigerant flowing out of the indoor heat exchangers 51a to 51c of the indoor units 5a to 5c and detected by the liquid side temperature sensors 61a to 61c is To (which needs to be individually referred to the indoor units 5a to 5c) If there is, it is described as Toa to Toc), the temperature of the air flowing into the indoor units 5a to 5c, and the suction temperature detected by the suction temperature sensors 63a to 63c is referred to Ts (individually referred to the indoor units 5a to 5c) If it is necessary to do so, the refrigerant subcooling degree on the refrigerant outlet side of the indoor heat exchangers 51a to 51c of the indoor units 5a to 5c is referred to SC (individually referred to the indoor units 5a to 5c). If it is necessary to do so, the refrigerant pressure after passing through the indoor expansion valves 52a to 52c and detected by the liquid pipe pressure sensors 64a to 64c is Pm (indoor unit 5). If you need to mention individually for the ～5C, it described as Pma～Pmc) to.

  In the example illustrated in FIG. 2, the outside air temperature during heating operation detected by the outside air temperature sensor 36 is −20 ° C., and the heating set temperature in the indoor units 5 a to 5 c is 24 ° C. Furthermore, let SCp be the performance compensation upper limit value of the refrigerant supercooling degree used when determining whether there is an indoor unit that does not exhibit the heating capacity. This performance compensation upper limit value SCp is determined in advance through testing or the like, and is, for example, 15 deg in the present embodiment.

  When the air conditioning apparatus 1 is performing the heating operation in the state described above, the detected values and calculated values in the indoor units 5a to 5c are values as illustrated in FIG. First, in the indoor unit 5a, the heat exchange outlet temperature Toa is 28 ° C., the suction temperature Tsa is 24 ° C., and the refrigerant supercooling degree SCa is high pressure saturation temperature Ths−heat exchange outlet temperature Toa = 2 deg. In other words, since the refrigerant supercooling degree SCa = 2 deg <performance compensation upper limit = 15 deg, it is determined that the indoor unit 5a exhibits sufficient heating capacity.

  Next, in the indoor unit 5b, the heat exchange outlet temperature Tob is 27 ° C., the suction temperature Tsb is 23 ° C., and the refrigerant supercooling degree SCb is high pressure saturation temperature Ths−heat exchange outlet temperature Tob = 3 deg. That is, since the refrigerant supercooling degree SCa = 3 deg <performance compensation upper limit = 15 deg, it is determined that the heating capacity is sufficiently exhibited also in the indoor unit 5b.

  In the indoor unit 5c, the heat exchange outlet temperature Toc and the suction temperature Tsc are both 20 ° C., and the refrigerant supercooling degree SCc is high pressure saturation temperature Ths−heat exchange outlet temperature Toc = 10 deg. In other words, since the refrigerant supercooling degree SCb = 10 deg <performance compensation upper limit = 15 deg, it is determined that the heating capacity is sufficiently exhibited even in the indoor unit 5c.

  However, in the indoor unit 5c, the heat exchange outlet temperature Toc and the suction temperature Tsc are both 20 ° C. as described above. The fact that the heat exchange outlet temperature Toc and the suction temperature Tsc are the same temperature indicates that the liquid refrigerant is stagnating in the indoor unit 5c, and the indoor unit 5c may not exhibit sufficient heating capacity. It shows sex. Therefore, as in the conventional air conditioner, when it is determined whether or not the heating capacity can be sufficiently exhibited by determining whether or not the refrigerant supercooling degree SC of each indoor unit is equal to or higher than the performance compensation upper limit SCp, There was a possibility that an indoor unit that could not exhibit the heating capability could be mistakenly determined that the heating capability was sufficiently exhibited.

  In contrast, in the present invention, when the air conditioner 1 performs the heating operation, the pressure obtained by subtracting the liquid pipe refrigerant pressure Pm detected by the liquid pipe pressure sensors 64a to 64c from the condensation pressure Ph detected by the discharge pressure sensor 31. The difference (hereinafter referred to as a pressure difference ΔP. Also, when it is necessary to individually refer to the indoor units 5a to 5c, the difference is described as ΔPa to ΔPc) is calculated periodically (for example, every 30 seconds). Then, it is determined whether or not the indoor unit is capable of exerting the heating capability based on whether or not the pressure difference ΔP is smaller than a predetermined pressure difference (hereinafter referred to as a threshold pressure difference ΔPs). Here, the threshold pressure difference ΔPs is obtained by performing a test or the like in advance and stored in the storage unit 220. When the pressure difference ΔP is smaller than the threshold pressure difference ΔPs, the indoor expansion valves 52a to 52c are used as refrigerants. Is a value that has been found not to flow. In this embodiment, the threshold pressure difference ΔPs is 0.2 MPa.

  As described above, the liquid refrigerant stays in the indoor unit 5c where the heating capability cannot be exhibited. At this time, the pressure difference ΔP is considered to be 0 MPa, or less than the threshold pressure difference ΔPs. Therefore, by looking at the pressure difference ΔP, it is possible to accurately determine whether or not the liquid refrigerant is retained in the indoor unit, that is, whether or not the indoor unit can sufficiently exhibit the heating capacity.

  Specifically, as shown in FIG. 2, in the indoor unit 5a, the liquid pipe refrigerant pressure Pma detected by the liquid pipe pressure sensor 64a is 0.2 MPa, and the pressure difference ΔPa = condensation pressure Ph−liquid pipe refrigerant pressure Pma. = 1.8−0.2 = 1.6 MPa, so the pressure difference ΔPa> 0.2 MPa, and it is determined that the heating capacity is sufficiently exhibited in the indoor unit 5a. In the indoor unit 5b, the liquid pipe refrigerant pressure Pmb detected by the liquid pipe pressure sensor 64b is 0.4 MPa, and the pressure difference ΔPb = condensing pressure Ph−liquid pipe refrigerant pressure Pmb = 1.8−0.4 = 1. Therefore, the pressure difference ΔPb> 0.2 MPa, and it is determined that the heating capacity is sufficiently exhibited even in the indoor unit 5b.

  On the other hand, in the indoor unit 5c, the liquid pipe refrigerant pressure Pma detected by the liquid pipe pressure sensor 64c is 1.8 MPa, and the pressure difference ΔPc = condensation pressure Ph−liquid pipe refrigerant pressure Pmc = 1.8-1.8. Since 0 MPa, the pressure difference ΔPc <0.2 MPa, and it is determined that the indoor unit 5c does not exhibit the heating capacity. In the conventional determination using only the refrigerant subcooling degree SCc, as described above, the indoor unit 5c is also determined to be able to sufficiently exert the heating capacity. However, the determination is made using the supercooling degree ratio SCr of the present invention. With this method, it can be accurately determined that the indoor unit 5c is not capable of exhibiting the heating capability.

  Next, control at the time of heating operation in the air-conditioning apparatus 1 of the present embodiment will be described with reference to FIG. FIG. 3 shows a flow of processing related to control performed by the CPU 210 of the outdoor unit control unit 200 when the air-conditioning apparatus 1 performs heating operation. In FIG. 3, ST represents a step, and the number following this represents a step number. Note that FIG. 3 mainly illustrates the processing related to the present invention, and other processing, for example, control of the refrigerant circuit 100 corresponding to the operating conditions such as the set temperature and the air volume instructed by the user. Description of general processing related to the harmony device 1 is omitted. Moreover, in the following description, the case where all the indoor units 5a to 5c are performing the heating operation will be described as an example.

  In the following description, among the indoor units to be controlled, among the 10 indoor units, the indoor units 5a to 5c shown in FIG. 1A and FIG. The same control is performed for the machine.

First, CPU 210 determines whether or not the user's operation instruction is a heating operation instruction (ST1).
If it is not a heating operation instruction (ST1-No), the CPU 210 executes a cooling / dehumidifying operation start process that is a start process of a cooling operation or a dehumidifying operation (ST11). Here, the cooling / dehumidifying operation start process is a process performed when the CPU 210 operates the four-way valve 22 to set the refrigerant circuit 100 to the cooling cycle, and when the cooling operation or the dehumidifying operation is first performed. Then, the CPU 210 activates the compressor 21 and the outdoor fan 27 at a predetermined rotational speed, and controls the driving of the indoor fans 55a to 55c and the indoor expansion valves 52a to 52c with respect to the indoor units 5a to 5c via the communication unit 230. Is instructed to adjust the opening degree of the air and starts control of the cooling operation or the dehumidifying operation (ST12), and the process proceeds to ST8.

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

  Next, the CPU 210 starts the heating operation control (ST3). At the start of heating operation control, the CPU 210 activates the compressor 21 and the outdoor fan 27 at a rotational speed corresponding to the required capacity from the indoor units 5a to 5c. The CPU 210 takes in the discharge temperature of the compressor 21 detected by the discharge temperature sensor 33 via the sensor input unit 240 and adjusts the opening degree of the outdoor expansion valve 24 according to the taken-in discharge temperature. Furthermore, CPU210 transmits the driving | operation start signal to the effect of starting heating operation via the communication part 230 with respect to indoor unit 5a-5c.

  The CPUs 510a to 510c of the indoor unit control means 500a to 500c of the indoor units 5a to 5c that have received the operation start signals via the communication units 530a to 530c turn the indoor fans 55a to 55c at the number of rotations according to the air volume instruction of the user. The interior of the indoor heat exchangers 51a to 51c is started so that the refrigerant supercooling degree at the refrigerant outlets (liquid pipe connection parts 53a to 53c side) becomes the target refrigerant subcooling degree (for example, 6 deg) at the start of operation. The opening degree of the expansion valves 52a to 52c is adjusted. Here, the target refrigerant subcooling degree is a value obtained by performing a test or the like in advance and stored in the storage units 530a to 530c, and it has been confirmed that the heating capacity is sufficiently exhibited in each indoor unit. Value. Note that the CPUs 510a to 510c are configured so that the above-described target refrigerant subcooling degree at the start of the operation becomes the above-described target refrigerant subcooling degree until the state of the refrigerant circuit 100 is stabilized after the start of the heating operation (for example, for 3 minutes from the start of operation). The opening degree of the expansion valves 52a to 52c is adjusted.

  Next, the CPU 210 takes in the condensing pressure Ph detected by the discharge pressure sensor 31 via the sensor input unit 240, and sends the liquid pipe refrigerant pressure Pm (Pma to Pmc) from each of the indoor units 5 a to 5 c via the communication unit 230. (ST4). The liquid pipe refrigerant pressure Pm is detected by the CPUs 510a to 510c via the sensor input units 540a to 540c in the indoor units 5a to 5c via the sensor input units 540a to 540c, and the communication units 530a to 530c. This is transmitted to the outdoor unit 2. Each detection value described above is captured by each CPU and stored in each storage unit at predetermined time intervals (for example, every 30 seconds).

  Next, the CPU 210 obtains a pressure difference ΔP using the condensation pressure Ph and the liquid pipe refrigerant pressure Pm taken in ST4 (ST5). As described above, the pressure difference ΔP is obtained by subtracting the liquid refrigerant pressure Pm from the condensation pressure Ph.

  Next, CPU 210 determines whether or not pressure difference ΔP obtained in ST5 is smaller than threshold pressure difference ΔPs (ST6). If pressure difference ΔP is not smaller than threshold pressure difference ΔPs (ST6-No), CPU 210 advances the process to ST8. If pressure difference (DELTA) P is smaller than threshold pressure difference (DELTA) Ps (ST6-Yes), CPU210 will perform non-heating cancellation control (ST7) and will advance a process to ST8.

  Here, the non-heating cancellation control is control performed to improve the heating capacity of the indoor unit 5c by causing the refrigerant staying in the indoor unit 5c, which has not been able to exhibit the heating capacity, to flow out of the indoor unit 5c. For example, the CPU 210 has a maximum value (refrigerant supercooling degree of the indoor unit 5c: 10 deg) and a minimum value (refrigerant supercooling degree of the indoor unit 5a: 2 deg) among the refrigerant supercooling degrees SCa to SCc of the indoor units 5a to 5c. The average refrigerant supercooling degree that is the average value of these: (2 + 10) / 2 = 6 deg is obtained, and the average refrigerant supercooling degree and the high-pressure saturation temperature Ths are transmitted to the indoor units 5a to 5c via the communication unit 230. Send. The CPUs 510a to 510c of the indoor units 5a to 5c that have received the average refrigerant supercooling degree and the high pressure saturation temperature Ths via the communication units 530a to 530c, respectively, use the liquid side temperature sensors 61a to 61c from the high pressure saturation temperature Ths received from the outdoor unit 2. The refrigerant subcooling degrees SCa to SCc are obtained by subtracting the heat exchange outlet temperatures Toa to Toc detected in step S3 so that the obtained refrigerant subcooling degrees SCa to SCc become the average refrigerant subcooling degree received from the outdoor unit 2. The opening degree of the indoor expansion valves 52a to 52c is adjusted.

  When the non-heating cancellation control as described above is performed, in the indoor units 5a and 5b having the refrigerant subcooling degree SC smaller than the average refrigerant subcooling degree (6 deg), the refrigerant subcooling degrees SCa and SCb are set to the average refrigerant subcooling degree. Since the opening degree of the indoor expansion valves 52a and 52b is throttled to increase the liquid refrigerant pressure Pma and Pmb of the indoor expansion valves 52a and 52b.

  At this time, in the indoor unit 5c in which the refrigerant subcooling degree Sc is larger than the average refrigerant subcooling degree, the liquid pipe refrigerant pressures Pma and Pmb of the indoor expansion valves 52a and 52b are decreased, whereby the liquid pipe refrigerant pressure Pmc of the indoor expansion valve 52c is reduced. The pressure difference ΔPc increases. Thereby, the liquid refrigerant staying in the indoor heat exchanger 51c of the indoor unit 5c flows out to the liquid pipe 8 and the liquid refrigerant stays in the indoor unit 5c is eliminated, so that the heating capacity of the indoor unit 5c is increased.

  CPU210 which finished the process of ST7 judges whether there exists the operation mode switching instruction | indication by a user (ST8). 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). If there is an operation mode switching instruction (ST8-Yes), the CPU 210 returns the process to ST1. When there is no operation mode switching instruction (ST8-No), the CPU 210 determines whether or not there is an operation stop instruction by the user (ST9). The operation stop instruction indicates that all the indoor units 5a to 5c stop the operation.

  If there is an operation stop instruction (ST9-Yes), the CPU 210 executes an operation stop process (ST10) and ends the process. In the operation stop process, the CPU 210 stops the compressor 21 and the outdoor fan 27 and fully closes the outdoor 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. The CPUs 510a to 510c of the indoor units 5a to 5c that have received the operation stop signals via the communication units 530a to 530c stop the indoor fans 55a to 55c and fully close the indoor expansion valves 52a to 52c.

  If there is no operation stop instruction in ST9 (ST9-No), CPU 210 determines whether or not the current operation is a heating operation (ST13). If the current operation is the heating operation (ST13-Yes), the CPU 210 returns the process to ST3. If the current operation is not the heating operation (ST13-No), that is, if the current operation is the cooling operation or the dehumidifying operation, the CPU 210 returns the process to ST12.

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Outdoor unit 5a-5c Indoor unit 31 Discharge pressure sensor 51a-51c Indoor heat exchanger 52a-52c Indoor expansion valve 61a-61c Liquid side temperature sensor 63a-63c Suction temperature sensor 64a-64c Liquid pipe pressure sensor 100 Refrigerant circuit 200 Outdoor unit controller 210 CPU
500a to 500c Indoor unit controller 510a to 510c CPU
Ph Condensation pressure Pm Liquid pipe refrigerant pressure SC Refrigerant supercooling degree To Heat exchange outlet temperature Ts Suction temperature ΔP Pressure difference ΔPs Threshold pressure difference

Claims (2)

An outdoor unit having a compressor and a condensation pressure detecting means for detecting the condensation pressure;
An indoor heat exchanger, an indoor expansion valve, and a liquid pipe pressure detecting means for detecting a liquid pipe refrigerant pressure that is a pressure of a refrigerant flowing out of the indoor expansion valve when the indoor heat exchanger functions as a condenser A plurality of indoor units having
The outdoor unit is installed above the plurality of indoor units, and is an air conditioner having a height difference in the installation location of the plurality of indoor units,
When the indoor heat exchanger functions as a condenser, a pressure difference between the condensation pressure and the liquid pipe refrigerant pressure is calculated for each of the plurality of indoor units, and the pressure difference is a predetermined threshold value. If it is smaller than the pressure difference, it has a control means to determine that the indoor unit is not able to demonstrate the heating capacity,
An air conditioner characterized by that. When there is an indoor unit that does not exhibit the heating capability, the control means performs unheating cancellation control for improving the heating capability of the indoor unit.
The air conditioner according to claim 1.

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