JP2019132468A - Air conditioner - Google Patents

Abstract

To provide an air conditioner capable of calculating pressure loss in a refrigerant communication pipeline.SOLUTION: An air conditioner 100 includes: a refrigerant circuit including a compressor 11, an outdoor heat exchanger 12, an electronic expansion valve 15, an indoor heat exchanger 22, and a gas refrigerant communication pipeline 37 arranged between the indoor heat exchanger 22 and the compressor 11; and a control device 50. The control device 50 has a pressure loss calculation operation S100 for calculating pressure loss ΔP of a refrigerant in the gas refrigerant communication pipeline 37, and in the pressure loss calculation operation S100, it monitors a compressor current of the compressor 11 in a state where an expansion valve opening Ev of the electronic expansion valve 15 is equal to or less than a predetermined opening, and based on the monitoring result, calculates the pressure loss ΔP.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an air conditioner that calculates a pressure loss of a refrigerant communication pipe.

  Conventionally, an air conditioner including a refrigerant circuit to which a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger are connected is known. Patent Document 1 (Japanese Patent Application Laid-Open No. 2014-167281) describes an air conditioner in which a pressure obtained by converting the evaporation temperature of a refrigerant into a saturation pressure is a low pressure of a refrigeration cycle.

  However, in patent document 1 (Unexamined-Japanese-Patent No. 2014-167281), there exists a subject that the pressure loss of refrigerant | coolant communication piping cannot be calculated.

  An air conditioner according to a first aspect includes a refrigerant circuit and a control device. The refrigerant circuit includes a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger. A refrigerant communication pipe is disposed between the indoor heat exchanger and the compressor. The control device has a pressure loss calculation operation for calculating the pressure loss of the refrigerant in the refrigerant communication pipe. In the pressure loss calculation operation, the control device monitors the compressor current in a state where the opening degree of the expansion valve is equal to or less than a predetermined opening degree. The control device calculates the pressure loss based on the monitoring result.

  In the air conditioner according to the second aspect, in the pressure loss calculation operation, the control device determines the time until the current value of the compressor shifts from rising to lowering after the opening of the expansion valve is set to a predetermined opening or less. Based on this, the pressure loss is calculated.

  In the air conditioner according to the third aspect, the control device fixes the frequency of the compressor to the first frequency and executes the pressure loss calculation operation.

  In the air conditioner according to the fourth aspect, the control device has a trial operation that is executed after the air conditioner is installed. The control device executes a pressure loss calculation operation during the test operation.

  In the air conditioner according to the fifth aspect, the control device calculates the suction pressure of the compressor by adding the pressure loss calculated by the pressure loss calculation operation to the evaporation pressure. The control device controls the operation capacity of the compressor using the calculated suction pressure in a normal operation different from the pressure loss calculation operation.

  In the air conditioner according to the sixth aspect, the control device determines the pipe length of the refrigerant communication pipe in proportion to the magnitude of the pressure loss calculated by the pressure loss calculation operation.

  The air conditioner according to the seventh aspect further includes a four-way switching valve. The four-way switching valve switches between the first refrigerant flow and the second refrigerant flow. The first refrigerant flow causes the indoor heat exchanger to act as an evaporator while the outdoor heat exchanger acts as a condenser. The second refrigerant flow causes the indoor heat exchanger to act as a condenser while the outdoor heat exchanger acts as an evaporator. A control apparatus interrupts the heating operation by a 2nd refrigerant | coolant flow, and performs the defrost operation | movement which melts the frost adhering to the outdoor heat exchanger by the 1st refrigerant | coolant flow. When the pressure loss calculated by the pressure loss calculation operation is large, the control device determines whether the four-way switching valve when returning from the end of the defrost operation to the heating operation before switching the first refrigerant flow to the second refrigerant flow. Reduce time by one hour.

  The air conditioner according to the eighth aspect does not have a suction pressure sensor that measures the pressure of the refrigerant sucked into the compressor.

It is a piping system figure of an air harmony device. It is a control block diagram of an air conditioning apparatus. It is a flowchart of a pressure loss calculation operation. It is a time chart of pressure loss calculation operation. It is the graph which showed the correlation with the time to the peak of the compressor current value after the pressure loss of refrigerant | coolant communication piping, and an expansion valve closure. It is a piping system figure of the air harmony device of modification 1. It is a piping system figure of the air harmony device of modification 2. It is a flowchart of the heating operation return of the modification 2.

<Air conditioning device>
(1) Whole structure The whole structure of the air conditioning apparatus 100 of this embodiment is demonstrated using FIG.1 and FIG.2. In addition, in FIG. 1, the whole structure of the air conditioning apparatus 100 is represented with the piping system diagram. Moreover, in FIG. 2, the control structure of the air conditioning apparatus 100 is represented by the control block diagram.

  As shown in FIG. 1, the air conditioning apparatus 100 is an apparatus that cools a room such as a building using a vapor compression refrigeration cycle. The air conditioning apparatus 100 is a dedicated cooling apparatus. The air conditioner 100 includes an outdoor unit 10, an indoor unit 20, and a control device 50.

(1-1) Outdoor unit The outdoor unit 10 is provided outside the building. The outdoor unit 10 includes a compressor 11, an outdoor heat exchanger 12, an outdoor fan 13, an outdoor fan motor 14, and an electronic expansion valve 15 as an expansion valve.

  The compressor 11 sends out the refrigerant gas from a low pressure to a high pressure. A suction pipe 31 is connected to the suction side of the compressor 11. A discharge pipe 32 is connected to the discharge side of the compressor 11. A discharge pipe temperature sensor 61 is provided in the vicinity of the compressor 11 of the discharge pipe 32. The discharge pipe temperature sensor 61 detects the discharge pipe temperature.

  The outdoor heat exchanger 12 exchanges heat between air and the refrigerant, and condenses the refrigerant gas into a refrigerant liquid. The inlet side of the outdoor heat exchanger 12 is connected to the discharge pipe 32. The outlet side of the outdoor heat exchanger 12 is connected to the liquid pipe. An outdoor heat exchanger intermediate temperature sensor 62 is provided in the middle of the refrigerant passage of the outdoor heat exchanger 12. The outdoor heat exchanger intermediate temperature sensor 62 detects the outdoor heat exchanger intermediate temperature.

  The outdoor fan 13 is driven by an outdoor fan motor 14 and forms a ventilation path for the outdoor heat exchanger 12.

  The electronic expansion valve 15 expands the refrigerant liquid into a gas-liquid mixed refrigerant. The electronic expansion valve 15 is electrically driven, and an operation for increasing or decreasing the opening degree is performed.

  Here, as a matter to be noted, the air conditioner 100 is not provided with a device that detects the suction pressure Ps of the compressor 11 such as a suction pressure sensor. Further, the air conditioner 100 is not provided with a refrigerant amount adjusting container such as a receiver or an accumulator.

(1-2) Indoor unit The indoor unit 20 is provided in the room of a building. The indoor unit 20 includes an indoor heat exchanger 22, an indoor fan 23, and an indoor fan electric motor 24.

  The indoor heat exchanger 22 exchanges heat between air and refrigerant, and evaporates the gas-liquid mixed refrigerant into refrigerant gas. The inlet side of the indoor heat exchanger 22 is connected to the liquid refrigerant communication pipe 36. The outlet side of the indoor heat exchanger 22 is connected to a gas refrigerant communication pipe 37 as a refrigerant communication pipe. An indoor heat exchanger inlet temperature sensor 63 is provided on the inlet side of the indoor heat exchanger 22. The indoor heat exchanger inlet temperature sensor 63 detects the indoor heat exchanger inlet temperature. An indoor heat exchanger intermediate temperature sensor 64 is provided in the middle of the refrigerant passage of the indoor heat exchanger 22. The indoor heat exchanger intermediate temperature sensor 64 detects the indoor heat exchanger intermediate temperature.

  The indoor fan 23 is driven by an indoor fan motor 24 and forms a ventilation path for the indoor heat exchanger 22. An indoor intake air temperature sensor 65 is provided on the suction side of the indoor fan 23. The indoor intake air temperature sensor 65 detects the indoor intake air temperature.

(1-3) Refrigerant Communication Pipe The gas refrigerant communication pipe 37 serving as the refrigerant communication pipe is disposed between the indoor heat exchanger 22 and the compressor 11. The liquid refrigerant communication pipe 36 is disposed between the electronic expansion valve 15 and the indoor heat exchanger 22.

  The liquid refrigerant communication pipe 36 and the gas refrigerant communication pipe 37 connect the outdoor unit 10 and the indoor unit 20. The liquid refrigerant communication pipe 36 and the gas refrigerant communication pipe 37 are refrigerant pipes constructed on site when the air conditioner 100 is installed at an installation location such as a building. As the liquid refrigerant communication pipe 36 and the gas refrigerant communication pipe 37, pipes having various lengths and pipe diameters are used according to installation conditions such as an installation location and a combination of the outdoor unit 10 and the indoor unit 20.

(1-4) Control Device As shown in FIG. 2, the control device 50 includes an outdoor side control unit 51 and an indoor side control unit 52. The air conditioner 100 controls each device of the outdoor unit 10 and the indoor unit 20 by the control device 50. Specifically, the control device 50 performs operation control of the entire air conditioner 100 by communication connection between the outdoor side control unit 51 and the indoor side control unit 52.

  The control device 50 is connected to the discharge pipe temperature sensor 61, the outdoor heat exchanger intermediate temperature sensor 62, the indoor heat exchanger inlet temperature sensor 63, the indoor heat exchanger intermediate temperature sensor 64, and the indoor intake air temperature sensor 65. The control device 50 receives detection signals from these sensors. In addition, the control device 50 controls the compressor 11, the outdoor fan motor 14, the electronic expansion valve 15, and the indoor fan motor 24 based on these detection signals and the like.

  Specifically, the control device 50 controls the operating frequency of the compressor 11 (hereinafter referred to as the compressor frequency Fc) and controls the operating capacity of the compressor 11. The control device 50 monitors the current value supplied to the compressor 11 (hereinafter, the compressor current value Ic). The control device 50 controls the opening degree of the electronic expansion valve 15 (hereinafter, expansion valve opening degree Ev).

(2) Cooling Operation The cooling operation of the air conditioner 100 will be described with reference to FIG.

  The high-temperature and high-pressure refrigerant gas compressed by the compressor 11 flows toward the outdoor heat exchanger 12. In the outdoor heat exchanger 12, the high-temperature and high-pressure refrigerant gas is deprived of heat by air and condensed into a refrigerant liquid. The condensed refrigerant liquid flows toward the electronic expansion valve 15.

  The refrigerant liquid is expanded into the gas-liquid mixed refrigerant by the electronic expansion valve 15. The gas-liquid mixed refrigerant flows toward the indoor heat exchanger 22 via the liquid refrigerant communication pipe 36. In the indoor heat exchanger 22, the gas-liquid mixed refrigerant is heated by air and evaporated into refrigerant gas. The evaporated refrigerant gas is sucked into the compressor 11 via the gas refrigerant communication pipe 37.

(3) Trial Operation Trial operation of the air conditioner 100 will be described.

  The test operation is a test operation after the air conditioner 100 is installed. Here, the installation of the air conditioner 100 includes updating the outdoor unit 10 and updating the indoor unit 20. In the trial operation, the cooling operation is executed, and from the compressor start control to the normal control is executed. In the compressor activation control, the compressor frequency Fc and the expansion valve opening Ev are increased in stages after the activation.

(4) Pressure Loss Calculation Operation The pressure loss calculation operation S100 will be described with reference to FIGS.

  The pressure loss calculation operation S100 is an operation for calculating the pressure loss ΔP of the gas refrigerant communication pipe 37 as the refrigerant communication pipe based on the monitoring result of the compressor current. The pressure loss calculation operation S100 is executed during the test operation.

(4-1) Flow The flow of the pressure loss calculation operation S100 will be described with reference to FIG.

  In step S101, the control device 50 confirms whether or not the current trial operation is being performed. If the current trial operation is in progress, the process proceeds to step S102. If the current trial operation is not in progress, the process returns to step S101.

  In step S102, the control device 50 checks whether or not the current time is after the compressor start control. If the present is after the compressor start control, the process proceeds to step S103, and if the present is not after the compressor start control, the process returns to step S101.

  In step S103, the control device 50 fixes the compressor frequency Fc to the predetermined frequency Fc1 as the first frequency. The predetermined frequency Fc1 is stored in the control device 50 in advance.

  In step S104, the control device 50 confirms whether or not the compressor current value Ic is stable. Specifically, the control device 50 confirms whether or not the state where the compressor current value Ic is changed within a predetermined range ΔIc1 continues for a predetermined time ta as a condition that the compressor current value Ic is stable. If the compressor current value Ic becomes stable, the control device 50 proceeds to step S105.

  In step S105, the control device 50 sets the expansion valve opening Ev to a predetermined opening or less (fully closed in this embodiment). The expansion valve opening Ev being fully closed includes individual variations of the electronic expansion valve 15. Specifically, the expansion valve opening Ev being fully closed means that the electronic expansion valve 15 is closed, including variations in the flow rate of the electronic expansion valve 15 with respect to the expansion valve opening Ev commanded to the control device 50. (When the passage flow rate of the electronic expansion valve 15 is 0). For example, if the electronic expansion valve 15 is closed even if the expansion valve opening degree Ev commanded to the control device 50 is a predetermined opening degree of 0 or more, the expansion valve opening degree Ev is included in the fully closed state.

  In step S106, the control device 50 detects a peak arrival time tp that is a time from when the expansion valve opening degree Ev is fully closed until the compressor current value Ic reaches the peak value.

  Here, the peak value of the compressor current value Ic is a current value when the compressor current value Ic shifts from rising to falling. The peak arrival time tp is the time from when the expansion valve opening Ev is fully closed until the compressor current value Ic reaches the peak value.

  In step S107, the control device 50 checks whether or not a predetermined time tb has elapsed since the expansion valve opening degree Ev was fully closed. If the predetermined time tb has elapsed since the expansion valve opening degree Ev was fully closed, the control device 50 ends the pressure loss calculation operation S100.

  In the pressure loss calculation operation S100, the control device 50 operates the outdoor fan motor 14 in the strong wind mode and operates the indoor fan motor 24 in the low wind mode.

(4-2) Operation The operation of the pressure loss calculation operation S100 will be described with reference to FIG. In FIG. 4, the operation of the pressure loss calculation operation S100 will be described using a time chart of the compressor frequency Fc, the expansion valve opening Ev, and the compressor current value Ic.

  In step S102, it is confirmed that the compressor activation control has been completed. In step S103, the compressor frequency Fc is fixed to the predetermined frequency Fc1. In step S104, it is confirmed that the compressor current value Ic is stable. In step S105, the expansion valve opening degree Ev is fully closed.

  At this time, since the expansion valve opening degree Ev is fully closed, the upstream side (outdoor heat exchanger 12) and the downstream side (indoor heat exchanger 22 and gas refrigerant communication pipe 37) of the electronic expansion valve 15 are blocked. The Then, the refrigerant inside the indoor heat exchanger 22 and the gas refrigerant communication pipe 37 is sucked into the compressor 11.

  In the indoor heat exchanger 22, since the indoor fan 23 is operated in the low wind mode by the indoor fan motor 24, heat is exchanged between the refrigerant and the air. Therefore, the refrigerant in the indoor heat exchanger 22 is evaporated and sucked into the compressor 11.

  When all the refrigerant inside the indoor heat exchanger 22 and the gas refrigerant communication pipe 37 is sucked into the compressor 11, the inside of the indoor heat exchanger 22 and the gas refrigerant communication pipe 37 is in a vacuum state, and the compressor 11 However, since the refrigerant gas is not compressed, the work amount of the compressor 11 is reduced. When the work amount of the compressor 11 decreases, the compressor current value Ic decreases.

  That is, when the compressor current value Ic reaches the peak value, all the refrigerant inside the indoor heat exchanger 22 and the gas refrigerant communication pipe 37 is sucked into the compressor 11. At this time, the inside of the indoor heat exchanger 22 and the gas refrigerant communication pipe 37 is in a vacuum state.

  In the outdoor heat exchanger 12, since the outdoor fan 13 is operated in the strong wind mode by the outdoor fan motor 14, heat exchange between the refrigerant and the air is performed. Therefore, the refrigerant gas discharged by the compressor 11 is condensed and stays in the outdoor heat exchanger 12 as a refrigerant liquid.

  In step S106, the peak arrival time tp is detected. As described above, the peak arrival time tp is the time from when the expansion valve opening Ev is fully closed until the compressor current value Ic reaches the peak value.

  In step S107, since the predetermined time tb has elapsed since the expansion valve opening degree Ev is fully closed, the pressure loss calculation operation S100 is terminated.

(4-3) Effect The correlation between the pressure loss ΔP and the peak arrival time tp will be described with reference to FIG. In FIG. 5, the correlation between the pressure loss ΔP and the peak arrival time tp is represented by a graph.

  As described above, when the compressor current value Ic reaches the peak value, all the refrigerant inside the indoor heat exchanger 22 and the gas refrigerant communication pipe 37 is sucked into the compressor 11 and is in a vacuum state.

  Here, the internal volume of the indoor heat exchanger 22 is constant. The size of the internal volume of the gas refrigerant communication pipe 37 is proportional to the pipe length. That is, the size of the internal volume of the indoor heat exchanger 22 and the gas refrigerant communication pipe 37 is proportional to the pipe length of the gas refrigerant communication pipe 37.

  Further, in the air conditioner 100, the amount of refrigerant charged differs depending on the pipe length of the gas refrigerant communication pipe 37. Specifically, the longer the pipe length of the gas refrigerant communication pipe 37, the larger the amount of charged refrigerant.

  Therefore, in the pressure loss calculation operation S100, the longer the pipe length of the gas refrigerant communication pipe 37 is, the more the compressor 11 needs to suck more refrigerant. That is, the peak arrival time tp becomes longer as the pipe length of the gas refrigerant communication pipe 37 is longer.

  The pipe length of the gas refrigerant communication pipe 37 is proportional to the pressure loss ΔP of the gas refrigerant communication pipe 37. Therefore, the length of the peak arrival time tp is proportional to the magnitude of the pressure loss ΔP of the gas refrigerant communication pipe 37. Specifically, the shorter the peak arrival time tp, the smaller the pressure loss ΔP, and the longer the peak arrival time tp, the greater the pressure loss ΔP.

  In the air conditioner 100, the correlation between the peak arrival time tp and the pressure loss ΔP of the gas refrigerant communication pipe 37 is determined in advance by experiment, and the correlation between the peak arrival time tp and the pressure loss ΔP is stored in the control device 50. Yes.

  That is, the control device 50 can calculate the pressure loss ΔP of the gas refrigerant communication pipe 37 by detecting the peak arrival time tp. In this way, the air conditioner 100 can calculate the pressure loss ΔP of the gas refrigerant communication pipe 37 based on the peak arrival time tp of the compressor current value Ic.

(4-3-1) Calculation of Intake Pressure Ps In the air conditioning apparatus 100, the control device 50 calculates the evaporation pressure Pe from the evaporation temperature Te detected by the indoor heat exchanger intermediate temperature sensor 64, and calculates the calculated evaporation pressure Pe. Can be added to the calculated pressure loss ΔP to calculate the suction pressure Ps.

  In this way, the control device 50 can execute the refrigerant control based on the suction pressure Ps.

(4-3-2) Compressor Capacity Control In the air conditioner 100, the control device 50 causes the calculated suction pressure Ps to be constant at the target suction pressure Psm in a normal operation different from the pressure loss calculation operation S100. Thus, the operation capacity of the compressor 11 is controlled.

  Specifically, when the suction pressure Ps is higher than the target suction pressure Psm, the operation capacity of the compressor 11 is controlled to increase. On the other hand, when the suction pressure Ps is lower than the target suction pressure Psm, the operation capacity of the compressor 11 is controlled to be small. Here, the target suction pressure Psm is set to decrease when the operating capacity of the indoor unit 20 increases, and is set to increase when the operating capacity of the indoor unit 20 decreases.

  In this way, the control device 50 can control the operating capacity of the compressor 11 based on the suction pressure Ps.

(4-3-3) Determination of Pipe Length The magnitude of the pressure loss ΔP of the gas refrigerant communication pipe 37 is proportional to the pipe length of the gas refrigerant communication pipe 37. In the air conditioner 100, the correlation between the magnitude of the pressure loss ΔP of the gas refrigerant communication pipe 37 and the pipe length of the gas refrigerant communication pipe 37 is determined in advance by experiment, and the magnitude of the pressure loss ΔP of the gas refrigerant communication pipe 37 and the gas are determined. A correlation with the pipe length of the refrigerant communication pipe 37 is stored in the control device 50.

  In this way, the control device 50 can determine the pipe length of the gas refrigerant communication pipe 37 based on the peak arrival time tp.

<Features>
(1)
Conventionally, in an air conditioner, an intake pressure sensor is provided, the intake pressure sensor detects the intake pressure of the compressor, and refrigerant control is executed based on the detected intake pressure.

  However, in recent years, expensive pressure sensors tend to be deleted. Therefore, in the air conditioner, the evaporation temperature is detected by a temperature sensor provided in the middle of the evaporator, the evaporation pressure is calculated from the detected evaporation temperature, and refrigerant control is executed based on the evaporation pressure instead of the suction pressure. It was. In other words, in the air conditioner from which the suction pressure sensor is deleted, the refrigerant control is executed ignoring the pressure loss of the gas refrigerant communication pipe.

  However, when the pressure loss of the gas refrigerant communication pipe is ignored, the refrigerant control cannot be executed with high accuracy. Therefore, in the air conditioner from which the suction pressure sensor is deleted, it is necessary to calculate the pressure loss of the gas refrigerant communication pipe in order to execute the refrigerant control with high accuracy. In such a background, the time (the peak arrival time tp in this embodiment) until the current value of the compressor shifts from rising to lowering after the expansion valve is set to a predetermined opening or less, and the pressure of the gas refrigerant communication pipe It was confirmed that there was a correlation with loss.

  The air conditioning apparatus 100 includes a refrigerant circuit and a control device 50. The refrigerant circuit includes a compressor 11, an outdoor heat exchanger 12, an electronic expansion valve 15, and an indoor heat exchanger 22. A gas refrigerant communication pipe 37 is disposed between the indoor heat exchanger 22 and the compressor 11. The control device 50 includes a pressure loss calculation operation S100 for calculating the pressure loss ΔP of the refrigerant in the gas refrigerant communication pipe 37. In the pressure loss calculation operation S100, the control device 50 monitors the compressor current of the compressor 11 in a state where the expansion valve opening Ev of the electronic expansion valve 15 is set to a predetermined opening or less. The control device 50 calculates the pressure loss ΔP based on the monitoring result.

  With such a configuration, in the air conditioner 100, the pressure loss ΔP of the gas refrigerant communication pipe 37 is based on the compressor current after the expansion valve opening Ev of the electronic expansion valve 15 is set to a predetermined opening or less. Calculated. In this way, the air conditioner 100 can calculate the pressure loss ΔP of the gas refrigerant communication pipe 37 based on the monitoring result of the compressor current.

(2)
In the air conditioner 100, the control device 50, in the pressure loss calculation operation S100, reaches the peak arrival time tp until the compressor current value Ic shifts from rising to falling after the expansion valve opening Ev is made equal to or less than the predetermined opening. Based on the above, the pressure loss ΔP is calculated.

  Here, the peak arrival time tp is the time from when the expansion valve opening Ev is fully closed until the compressor current value Ic reaches the peak value. The peak value of the compressor current value Ic is a current value when the compressor current value Ic shifts from rising to falling.

  The peak value of the compressor current value Ic is a current value when the compressor current value Ic shifts from rising to falling when the compressor current value Ic is monitored at a predetermined sampling period. For example, it is not included when the compressor current value Ic instantaneously shifts from rising to falling.

  With such a configuration, in the air conditioner 100, based on the peak arrival time tp until the compressor current value Ic shifts from rising to lowering after the expansion valve opening Ev is made equal to or less than the predetermined opening. The pressure loss ΔP of the gas refrigerant communication pipe 37 is calculated. Thus, in the air conditioning apparatus 100, the pressure loss ΔP of the gas refrigerant communication pipe 37 can be calculated based on the peak arrival time tp.

(3)
In the air conditioner 100, the control device 50 fixes the compressor frequency Fc to the predetermined frequency Fc1, and executes the pressure loss calculation operation S100.

  With such a configuration, in the air conditioner 100, the compressor frequency Fc is fixed to the predetermined frequency Fc1, and the pressure loss calculation operation S100 is performed. In this way, the air conditioner 100 can calculate the pressure loss ΔP of the gas refrigerant communication pipe 37.

(4)
In the air conditioner 100, the control device 50 has a trial run that is executed after the air conditioner 100 is installed. The control device 50 executes the pressure loss calculation operation S100 during the test operation.

  By setting it as such a structure, in the air conditioning apparatus 100, pressure loss calculation operation | movement S100 is performed at the time of the trial operation after the air conditioning apparatus 100 is installed. In this way, in the air conditioner 100, only the installer performs the pressure loss calculation operation S100 during the trial operation, so that the user does not need to execute the pressure loss calculation operation S100.

(5)
In the air conditioner 100, the control device 50 calculates the suction pressure Ps of the compressor 11 by adding the pressure loss ΔP calculated in the pressure loss calculation operation S100 to the evaporation pressure Pe. The control device 50 controls the operating capacity of the compressor 11 using the calculated suction pressure Ps in a normal operation different from the pressure loss calculation operation S100.

  In this way, the control device 50 can control the operating capacity of the compressor 11 based on the suction pressure Ps.

(6)
In the air conditioner 100, the control device 50 determines the pipe length of the gas refrigerant communication pipe 37 in proportion to the magnitude of the pressure loss ΔP calculated by the pressure loss calculation operation S100.

(7)
The air conditioner 300 further includes a four-way switching valve 18. The four-way switching valve 18 switches between the first refrigerant flow and the second refrigerant flow. The first refrigerant flow causes the indoor heat exchanger 22 to act as an evaporator while the outdoor heat exchanger 12 acts as a condenser. The second refrigerant flow causes the indoor heat exchanger 22 to act as a condenser while the outdoor heat exchanger 12 acts as an evaporator. The control apparatus 50 interrupts the heating operation by the second refrigerant flow, and performs the defrost operation to melt the frost attached to the outdoor heat exchanger 12 by the first refrigerant flow. When the pressure loss ΔP calculated by the pressure loss calculation operation S100 is large, the control device 50 causes the four-way switching valve 18 at the time of returning from the end of the defrost operation to the heating operation to switch the first refrigerant flow to the second refrigerant flow. The predetermined time tc until the previous time is shortened.

  In the air conditioner 300, when the gas refrigerant communication pipe 37 is long, the switching sound of the four-way switching valve 18 is difficult to propagate to the indoor unit 20, so the predetermined time tc before switching the four-way switching valve 18 is shortened, Defrost time can be shortened.

(8)
The air conditioner 100 does not have a suction pressure sensor that measures the pressure of the refrigerant sucked into the compressor 11.

  In this way, expensive pressure sensors can be eliminated and product costs can be reduced.

<Modification 1>
(1) Whole structure The air conditioning apparatus 200 of the modification 1 is demonstrated using FIG. In addition, in FIG. 6, the whole structure of the air conditioning apparatus 200 is represented by the piping system diagram.

  The air conditioner 200 differs from the air conditioner 100 only in that the outdoor heat exchanger intermediate temperature sensor 62 is deleted. Therefore, in the air conditioning apparatus 200, detailed description of each device common to the air conditioning apparatus 100 is omitted.

(2) Calculation of discharge pressure Pd Calculation of the discharge pressure Pd of the air conditioning apparatus 200 will be described.

  As described above, in the cooling operation, the controller 50 calculates the evaporation pressure Pe from the evaporation temperature Te detected by the indoor heat exchanger intermediate temperature sensor 64, and adds the calculated pressure loss ΔP to the calculated evaporation pressure Pe. The suction pressure Ps is calculated.

  Further, the control device 50 calculates the discharge pressure Pd based on the compressor performance characteristics, the calculated suction pressure Ps, the compressor current value Ic, and the compressor frequency Fc. Specifically, the compressor performance characteristic is a function representing a correlation among the suction pressure Ps, the discharge pressure Pd, the compressor current value Ic, and the compressor frequency Fc. The compressor performance characteristics are stored in advance in the control device 50 of the air conditioner 200.

  Conventionally, for example, in the air conditioner 100, in the cooling operation, the condensation temperature Tc is detected by the outdoor heat exchanger intermediate temperature sensor 62, the condensation pressure Pc is calculated from the detected condensation temperature Tc, and the condensation pressure Pd is substituted for the discharge pressure Pd. The refrigerant control was executed based on Pc.

  However, in the air conditioner 200, the discharge pressure Pd can be calculated based on the calculated suction pressure Ps and the compressor performance characteristics without using the outdoor heat exchanger intermediate temperature sensor 62. Therefore, in the air conditioning apparatus 200, the outdoor heat exchanger intermediate temperature sensor 62 can be deleted, and the product cost can be reduced.

<Modification 2>
(1) Whole structure The air conditioning apparatus 300 of the modification 2 is demonstrated using FIG. In addition, in FIG. 7, the whole structure of the air conditioning apparatus 300 is represented by the piping system diagram.

  The air conditioning apparatus 300 is a cooling / heating apparatus. The air conditioner 300 differs from the air conditioner 100 only in that a second electronic expansion valve 16, a high pressure receiver 17, and a four-way switching valve 18 are added. Therefore, in the air conditioning apparatus 300, detailed description of the devices common to the air conditioning apparatus 100 is omitted.

  The four-way switching valve 18 causes the cooling operation as the first refrigerant flow that causes the indoor heat exchanger 22 to act as an evaporator while the outdoor heat exchanger 12 acts as a condenser, and causes the outdoor heat exchanger 12 to act as an evaporator. On the other hand, the heating operation as the second refrigerant flow that causes the indoor heat exchanger 22 to act as a condenser is switched.

  The high-pressure receiver 17 is a container for adjusting the amount of refrigerant for retaining excess refrigerant. The high-pressure receiver 17 is disposed between the electronic expansion valve 15 and the second electronic expansion valve 16. The second electronic expansion valve 16 functions as an expansion valve in the heating operation. The second electronic expansion valve 16 is disposed between the high-pressure receiver 17 and the outdoor heat exchanger 12.

(2) Heating operation The heating operation of the air conditioning apparatus 300 will be described.

  The high-temperature and high-pressure refrigerant gas compressed by the compressor 11 flows toward the indoor heat exchanger 22 via the four-way switching valve 18 and the gas refrigerant communication pipe 37. In the indoor heat exchanger 22, the high-temperature and high-pressure refrigerant gas is deprived of heat by air and condensed into a refrigerant liquid. The condensed refrigerant liquid flows toward the high-pressure receiver 17 via the liquid refrigerant communication pipe 36.

  The refrigerant liquid is expanded into the gas-liquid mixed refrigerant by the second electronic expansion valve 16. The gas-liquid mixed refrigerant flows toward the outdoor heat exchanger 12. In the outdoor heat exchanger 12, the gas-liquid mixed refrigerant is heated by air and evaporated to refrigerant gas. The evaporated refrigerant gas is sucked into the compressor 11 via the four-way switching valve 18.

(2-1) Calculation of discharge pressure Pd Calculation of the discharge pressure Pd in the heating operation of the air conditioning apparatus 300 will be described.

  Conventionally, in a heating operation of an air conditioner, a condensation temperature Tc is detected by an indoor heat exchanger intermediate temperature sensor, a condensation pressure Pc is calculated from the detected condensation temperature Tc, and based on the condensation pressure Pc as an alternative to the discharge pressure Pd. Refrigerant control was being executed. In other words, in the heating operation of the conventional air conditioner, the refrigerant control is executed ignoring the pressure loss of the gas refrigerant communication pipe. However, when the pressure loss of the gas refrigerant communication pipe is ignored, the refrigerant control cannot be executed with high accuracy.

  In the air conditioner 300, the control device 50 calculates the pressure loss ΔP of the gas refrigerant communication pipe 37 in the pressure loss calculation operation S100.

  In the heating operation, the controller 50 calculates the condensation pressure Pc from the condensation temperature Tc detected by the indoor heat exchanger intermediate temperature sensor 64, and calculates the calculated pressure loss ΔP to the calculated condensation pressure Pc (the absolute value of the pressure loss ΔP). The discharge pressure Pd can be calculated by adding values).

  Thus, in the air conditioning apparatus 300, the control apparatus 50 can perform refrigerant control based on the discharge pressure Pd in the heating operation.

(3) Defrosting operation Defrosting operation of the air conditioner 300 will be described.

  In the air conditioner 300, when the control device 50 determines that the defrost start condition of the outdoor heat exchanger 12 is satisfied, for example, when the temperature of the refrigerant in the outdoor heat exchanger 12 reaches the defrost start temperature, the heating operation is interrupted, A defrost operation is performed to melt frost attached to the outdoor heat exchanger 12.

  The so-called reverse cycle defrost operation is employed for the defrost operation, and is performed by switching the four-way switching valve 18 to the first refrigerant flow and causing the outdoor heat exchanger 12 to function as a condenser, similarly to the cooling operation. Thereby, the frost adhering to the outdoor heat exchanger 12 can be thawed.

  The defrost operation is performed until it is determined that the defrost completion condition of the outdoor heat exchanger 12 is satisfied, for example, when the temperature of the refrigerant in the outdoor heat exchanger 12 reaches the defrost completion temperature, and then returns to the heating operation.

(3-1) Return from Defrost Operation to Heating Operation Heating operation return S200 when the air-conditioning apparatus 300 returns from the defrost operation to the heating operation will be described.

(3-1-1) Flow The flow of heating operation return S200 will be described with reference to FIG.

  In step S201, the control device 50 is assumed to perform a defrost operation. In step S202, the control device 50 confirms whether the defrost completion condition is satisfied. If the defrost completion condition is satisfied, the process proceeds to step S203.

  In step S203, the control device 50 checks whether or not a predetermined time tc as the first time has elapsed since the defrost completion condition was satisfied. If the predetermined time tc has elapsed, the process proceeds to step S204. It is assumed that the predetermined time tc is stored in the control device 50 in advance. The length of the predetermined time tc is shortened if the pressure loss ΔP of the gas refrigerant communication pipe 37 is large.

  Specifically, the predetermined time tc is set so as to decrease as the pressure loss ΔP of the gas refrigerant communication pipe 37 increases. That is, the predetermined time tc is set short when the pressure loss ΔP of the gas refrigerant communication pipe 37 is large, and is set long when the pressure loss ΔP of the gas refrigerant communication pipe 37 is small.

  The predetermined time tc may be shortened when the pressure loss ΔP of the gas refrigerant communication pipe 37 is equal to or greater than a predetermined value.

  In step S204, the control device 50 switches the four-way switching valve 18 from the first refrigerant flow to the second refrigerant flow, and returns from the defrost operation to the heating operation.

(3-1-2) Effect The effect of heating operation return S200 will be described.

  In the air conditioner 300, when the gas refrigerant communication pipe 37 is long, the switching sound of the four-way switching valve 18 is not easily propagated to the indoor unit 20, and therefore, before the four-way switching valve 18 is switched after the defrost completion condition is satisfied. It is possible to shorten the predetermined time tc.

  In this way, the defrost time can be shortened.

<Other variations>
(1)
In the present embodiment and the first and second modifications, the operation frequency of the compressor 11 can be controlled and the operation capacity of the compressor 11 can be controlled. For example, the compressor 11 may have a constant operating capacity.

(2)
In the present embodiment and Modifications 1 and 2, the expansion valve opening Ev is fully closed in the pressure loss calculation operation S100. However, if the peak value of the compressor current value Ic can be detected, the expansion valve opening Ev. It is also possible to only reduce the to a predetermined opening.

  While the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as set forth in the claims. .

  The present invention is widely applicable to an air conditioner.

11 Compressor 12 Outdoor heat exchanger 15 Electronic expansion valve (expansion valve)
22 Indoor heat exchanger 37 Gas refrigerant communication pipe (refrigerant communication pipe)
50 control device 100 air conditioner

JP 2014-167281 A

Claims (8)

A compressor (11), an outdoor heat exchanger (12), an expansion valve (15), an indoor heat exchanger (22), and between the indoor heat exchanger (22) and the compressor (11). A refrigerant communication pipe (37) disposed in the refrigerant circuit;
A control device (50);
With
The control device (50)
A pressure loss calculation operation for calculating the pressure loss of the refrigerant in the refrigerant communication pipe (37),
In the pressure loss calculation operation, the current of the compressor is monitored in a state where the opening of the expansion valve (15) is equal to or less than a predetermined opening, and the pressure loss is calculated based on the monitoring result.
Air conditioner (100). In the pressure loss calculation operation, the control device (50) is configured to change the current value of the compressor (11) from rising to lowering after the opening of the expansion valve (15) is set to a predetermined opening or less. Calculating the pressure loss based on the time of
The air conditioner (100) according to claim 1. The controller (50) fixes the frequency of the compressor (11) to a first frequency, and executes the pressure loss calculation operation.
The air conditioner (100) according to claim 1 or 2. The control device (50)
Having a test run performed after the air conditioner (100) is installed;
Performing the pressure loss calculation operation during the test operation;
The air conditioner (100) according to any one of claims 1 to 3. The control device (50)
Adding the pressure loss calculated by the pressure loss calculation operation to the evaporation pressure to calculate the suction pressure of the compressor (11);
In a normal operation different from the pressure loss calculation operation, the operation capacity of the compressor (11) is controlled using the calculated suction pressure.
The air conditioner (100) according to any one of claims 1 to 4. The controller is
Determining the pipe length of the refrigerant communication pipe (37) in proportion to the magnitude of the pressure loss calculated by the pressure loss calculation operation;
The air conditioner (100) according to any one of claims 1 to 4. While the outdoor heat exchanger (12) acts as a condenser and the indoor heat exchanger (22) acts as an evaporator, the outdoor heat exchanger (12) acts as an evaporator. A four-way switching valve (18) that switches between a second refrigerant flow that causes the indoor heat exchanger (22) to act as a condenser, and
The control device (50)
The heating operation by the second refrigerant flow is interrupted, and the defrost operation is performed to melt the frost adhered to the outdoor heat exchanger (12) by the first refrigerant flow,
When the pressure loss calculated by the pressure loss calculation operation is large, the four-way switching valve (18) when returning from the end of the defrost operation to the heating operation changes the first refrigerant flow to the second refrigerant flow. Reduce the first time before switching,
The air conditioner (300) according to any one of claims 1 to 4. Not having a suction pressure sensor for measuring the pressure of the refrigerant sucked into the compressor (11);
The air conditioner (100) according to any one of claims 1 to 7.

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