JP5448566B2 - Multi air conditioner - Google Patents

Description

  The present invention relates to a multi-air conditioner in which a plurality of indoor units are connected in parallel to one outdoor unit.

  The plurality of indoor units connected to the multi-air conditioner are not necessarily installed at the same level, and are often installed at different levels with a height difference. In this case, when the height difference becomes large, the liquid refrigerant condensed due to the influence of gravity tends to accumulate in the indoor unit installed below during the heating operation. As a result, the heating capacity of the indoor unit installed below is lowered, and if this becomes prominent, there is a problem that non-heating occurs.

  Therefore, when heating operation is performed and it is found that there is an unheated indoor unit after a certain period of time, the heating target high pressure is increased by a certain value, or the unheated indoor unit is Japanese Patent Application Laid-Open No. H11-228707 proposes that unheating can be eliminated by changing the expansion valve opening or the target outlet temperature of the indoor heat exchanger.

  On the other hand, in order to accurately control the degree of supercooling during heating operation in a multi-air conditioner, the pressure loss is calculated taking into account the refrigerant pipe length of the indoor unit and the height difference between the outdoor unit and the indoor unit. Patent Document 2 proposes a highly efficient heating operation by obtaining a corrected degree of subcooling in consideration of the above and controlling the indoor expansion valve so that it is substantially within a certain range.

JP 2008-121970 A Japanese Patent Laid-Open No. 9-280681

However, in the one disclosed in Patent Document 1, the heating target high pressure, the target subcooling degree, or the target outlet temperature is changed when a heating operation is performed for a certain period of time and there is an unheated indoor unit. Because it is a thing, it is inevitable that it will become unheated once. Therefore, although temporarily, there is a problem that the person in the air-conditioning area is uncomfortable.
In addition, what is disclosed in Patent Document 2 calculates a correction value for the degree of supercooling in consideration of pressure loss due to the refrigerant pipe length, the height difference between the outdoor unit and the indoor unit, and the like, and based on the corrected degree of subcooling. Although supercooling degree control is performed, this makes it possible to perform highly efficient heating operation by accurately performing supercooling degree control during heating operation. It is not possible to prevent the occurrence of non-heating due to the installation.

  The present invention has been made in view of such circumstances, and even when a plurality of indoor units are installed with a height difference, a multi-air conditioner capable of preventing the occurrence of non-heating due to the difference. The purpose is to provide.

In order to solve the above problems, the multi-air conditioner of the present invention employs the following means.
That is, the multi-air conditioner according to the present invention includes an outdoor unit having a compressor, an outdoor heat exchanger and an outdoor expansion valve, an indoor heat exchanger and an indoor expansion valve, and the outdoor unit includes a gas side pipe and a liquid. A plurality of indoor units connected in parallel via a side pipe, and the outdoor unit and the indoor unit are provided with an outdoor control unit and an indoor control unit that are communicable with each other, during heating operation The opening degree of the indoor expansion valve is controlled by either the indoor control unit or the outdoor control unit so that the heat exchange outlet temperature or the refrigerant subcooling degree of the indoor unit becomes a target value. In the multi-type air conditioner, the outdoor control unit includes a target heat exchange outlet temperature or a target refrigerant subcooling degree used for controlling the indoor expansion valves of the plurality of indoor units installed with a height difference. Control target to be set Setting portion is provided, during installation, the initial value of the initial value or the target refrigerant supercooling degree of the target heat交出opening temperature, and a head difference and / or tubing pressure loss and the refrigerant property by the difference in height, it In response, the pressure saturation temperature of each indoor unit is calculated, the new target heat exchange outlet temperature or the target refrigerant subcooling degree is calculated, and set in the control target value setting unit, the indoor control unit or One of the outdoor control units is configured to control the opening of the indoor expansion valve based on the control target value set by the control target value setting unit.

According to the present invention, a plurality of indoor units are connected in parallel to one outdoor unit, and each outdoor unit and indoor unit are provided with an outdoor control unit and an indoor control unit that can communicate with each other. Control target value setting unit for setting a target heat exchange outlet temperature or a target refrigerant subcooling degree used to control each indoor expansion valve of a plurality of indoor units installed in the outdoor control unit of the air conditioner When installing, the initial value of the target heat exchange outlet temperature or the initial value of the target refrigerant supercooling degree is determined according to the head difference and / or pipe pressure loss and refrigerant physical properties due to the height difference. The pressure saturation temperature of each indoor unit is obtained, the new target heat exchange outlet temperature or the target refrigerant subcooling degree is calculated, and set in the control target value setting unit, and the indoor control unit or the outdoor control unit Either Since the opening of the indoor expansion valve is controlled based on the control target value set by the target value setting unit, even if multiple indoor units are installed with a large level difference, It is possible to set an appropriate target heat exchange outlet temperature or target refrigerant subcooling degree corresponding to the height difference with respect to the unit, and install it upward by controlling the indoor expansion valve of each indoor unit based on this Since the opening degree of the indoor expansion valve of the indoor unit that is being used becomes throttled, the accumulation of refrigerant in the heat exchanger of the indoor unit installed below can be suppressed. Accordingly, it is possible to prevent the heating capacity of the indoor unit installed below from being lowered, and to eliminate the occurrence of non-heating caused by the installation of a plurality of indoor units with a height difference. In addition, since the target heat exchange outlet temperature or the target refrigerant subcooling degree for each indoor unit can be set at a time on the outdoor unit side, the setting operation of the control target value can be simplified. Furthermore, since an appropriate target heat exchange outlet temperature or target refrigerant subcooling degree can be initially set when the multi-air conditioner is installed, it can be operated so as not to be unheated from the beginning of the operation.

The multi-air conditioner according to the present invention further includes an outdoor unit having a compressor, an outdoor heat exchanger and an outdoor expansion valve, an indoor heat exchanger and an indoor expansion valve, and the outdoor unit includes a gas side pipe and a liquid. A plurality of indoor units connected in parallel via a side pipe, and the outdoor unit and the indoor unit are provided with an outdoor control unit and an indoor control unit that are communicable with each other, during heating operation The opening degree of the indoor expansion valve is controlled by either the indoor control unit or the outdoor control unit so that the heat exchange outlet temperature or the refrigerant subcooling degree of the indoor unit becomes a target value. In the multi-type air conditioner, the outdoor control unit is installed with an input unit for inputting a height difference between the plurality of indoor units and the outdoor unit, and with a height difference based on an input value from the input unit. The plurality of indoor units The control target value calculating portion for calculating a target heat交出port temperature or target refrigerant supercooling degree is used for controlling the respective indoor expansion valves are provided, during installation, the over-the initial value or the target refrigerant of the target heat交出Inlet temperature With respect to the initial value of the degree of cooling, the height difference is input to the input unit, and based on the input value, the control target value calculation unit calculates the head difference due to the height difference and / or pipe pressure loss and refrigerant physical properties, The pressure saturation temperature of each indoor unit corresponding thereto is calculated, the new target heat exchange outlet temperature or the target refrigerant subcooling degree is calculated, and either the indoor control unit or the outdoor control unit controls the control target The opening degree of the indoor expansion valve is controlled based on the control target value calculated by the value calculation unit.

According to the present invention, a plurality of indoor units are connected in parallel to one outdoor unit, and each outdoor unit and indoor unit are provided with an outdoor control unit and an indoor control unit that can communicate with each other. An input unit for inputting a height difference between a plurality of indoor units and the outdoor unit to the outdoor control unit of the air conditioner, and a plurality of indoor units installed with a level difference based on an input value from the input unit A control target value calculation unit is provided for calculating a target heat exchange outlet temperature or a target refrigerant subcooling degree used for controlling each indoor expansion valve, and when installed, the initial value of the target heat exchange outlet temperature or the target refrigerant excess With respect to the initial value of the degree of cooling, the height difference is input to the input unit, and based on the input value, the control target value calculation unit calculates the head difference due to the height difference and / or pipe pressure loss and refrigerant physical properties, Each room accordingly Determination of pressure saturation temperature, to calculate a new said target heat交出port temperature or the target refrigerant supercooling degree, in any of the indoor control unit or the outdoor control unit, a control target value calculated by the control target value calculation unit Therefore, even if multiple indoor units are installed with a large difference in height, the difference in height between the multiple indoor units and the outdoor unit is configured. , The control target value calculation unit can calculate the appropriate target heat exchange outlet temperature or target refrigerant subcooling degree corresponding to the height difference for each indoor unit, and based on this, the indoor expansion of each indoor unit By controlling the valve, the opening of the indoor expansion valve of the indoor unit installed at the upper side becomes throttled, so that the refrigerant is stored in the heat exchanger of the indoor unit installed at the lower side. Can be suppressed. Accordingly, it is possible to prevent the heating capacity of the indoor unit installed below from being lowered, and to eliminate the occurrence of non-heating caused by the installation of a plurality of indoor units with a height difference. In addition, since the target heat exchange outlet temperature or the target refrigerant subcooling degree for each indoor unit can be set at a time on the outdoor unit side, the setting operation of the control target value can be simplified. Furthermore, since an appropriate target heat exchange outlet temperature or target refrigerant subcooling degree can be initially set when the multi-air conditioner is installed, it can be operated so as not to be unheated from the beginning of the operation.

  Furthermore, the multi air conditioner of the present invention is the above multi air conditioner, wherein the input unit is installed at a lowermost position in place of a height difference between the plurality of indoor units and the outdoor unit. It is an input unit for inputting a temperature difference between a target heat exchange outlet temperature for the indoor unit or a target refrigerant subcooling degree.

  According to the present invention, the input unit replaces the height difference between the plurality of indoor units and the outdoor unit, and the target heat exchange outlet temperature or the target refrigerant subcooling temperature for the indoor unit installed at the lowest position. Since it is an input unit for inputting the difference, the control target value calculation unit is configured to input the temperature difference based on the target heat exchange outlet temperature or the target refrigerant subcooling degree for the indoor unit installed at the lowest position. Appropriate target heat exchange outlet temperature or target refrigerant supercooling degree corresponding to the height difference for each indoor unit can be calculated, and based on this, the opening of the indoor expansion valve of each indoor unit is controlled and installed below It is possible to suppress the accumulation of refrigerant in the heat exchanger of the indoor unit. As a result, the heating capacity of the indoor unit installed below can be prevented from being lowered, and unheating caused by the installation of a plurality of indoor units with different heights can be eliminated.

  Furthermore, the multi air conditioner of the present invention is the multi air conditioner described above, wherein the control target value calculation unit is configured such that the control unit value calculation unit determines whether the plurality of indoor units and the outdoor units are different from each other. A difference in height is calculated, and based on the difference, a target heat exchange outlet temperature or a target refrigerant subcooling degree between the thermo-on indoor units can be calculated.

  According to the present invention, the control target value calculation unit calculates the height difference between the indoor units from the height difference between the plurality of indoor units and the outdoor unit, and based on the difference, the target heat exchange between the thermo-on indoor units is calculated. Since it is possible to calculate the outlet temperature or the target refrigerant subcooling degree, the target heat exchange outlet temperature or the target refrigerant subcooling degree only between the indoor units that are thermo-ONed can be calculated. Alternatively, the target refrigerant supercooling degree can be increased. As a result, it is possible to suppress a decrease in the heating capacity of the indoor unit that is thermo-on and to improve the heating performance.

  Furthermore, the multi air conditioner of the present invention is characterized in that, in any of the multi air conditioners described above, the control target value can be set from a remote controller of the plurality of indoor units. .

  According to the present invention, since the control target value can be set from each of the remote controllers of a plurality of indoor units, the target heat exchange outlet temperature or the target refrigerant subcooling degree for each indoor unit is collectively recorded on the outdoor unit side. It can be set from the remote controller of each indoor unit. Therefore, the convenience of setting the target heat exchange outlet temperature or the target refrigerant subcooling degree corresponding to the height difference of the indoor units can be further improved.

  Furthermore, in the multi air conditioner according to the present invention, in any of the multi air conditioners described above, the outdoor control unit sets a new control target value corresponding to a height difference between the plurality of indoor units. In this case, the heating target high pressure is configured to increase by a certain value.

  According to the present invention, the outdoor control unit is configured to increase the heating target high pressure by a certain value when a new control target value is set corresponding to the height difference of the plurality of indoor units. Control of the indoor expansion valve based on the newly set target heat exchange outlet temperature or target refrigerant supercooling level can not only suppress the accumulation of refrigerant in the heat exchanger of the indoor unit installed below, Even when the target high pressure is increased by a certain value, accumulation of liquid refrigerant in the indoor heat exchanger can be suppressed. Accordingly, it is possible to eliminate the occurrence of non-heating due to the installation of a plurality of indoor units with a height difference, and it is possible to minimize a decrease in capacity by increasing the high pressure.

  According to the present invention, it is possible to set an appropriate target heat exchange outlet temperature or a target refrigerant subcooling degree corresponding to the height difference of a plurality of indoor units, and the indoor expansion of each indoor unit based on this control target value By controlling the valve, the opening of the indoor expansion valve of the indoor unit installed at the upper side becomes throttled, so that the refrigerant is stored in the heat exchanger of the indoor unit installed at the lower side. Since it can suppress, the fall of the heating capability of the indoor unit installed below can be prevented, and generation | occurrence | production of the non-heating resulting from a plurality of indoor units being installed with a height difference can be eliminated. In addition, since the target heat exchange outlet temperature or the target refrigerant subcooling degree for each indoor unit can be set at a time on the outdoor unit side, the setting operation of the control target value can be simplified. Furthermore, since an appropriate target heat exchange outlet temperature or target refrigerant subcooling degree can be initially set when the multi-air conditioner is installed, it can be operated so as not to be unheated from the beginning of the operation.

It is a refrigerant circuit figure of the multi air harmony machine concerning a 1st embodiment of the present invention. It is a schematic diagram which shows the installation state of the several indoor unit in the multi air conditioner shown in FIG. It is explanatory drawing which shows the example of a setting of the target heat exchange outlet temperature with respect to the several indoor unit in the multi air conditioner shown in FIG.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
FIG. 1 shows a refrigerant circuit diagram of a multi-air conditioner according to this embodiment. The multi air conditioner 1 includes one outdoor unit 2, a gas side pipe 4 and a liquid side pipe 5 led out from the outdoor unit 2, and a branching device 6 between the gas side pipe 4 and the liquid side pipe 5. And a plurality of indoor units 7A and 7B connected in parallel.

  The outdoor unit 2 heats an inverter-driven compressor 21 that compresses refrigerant, an oil separator 22 that separates refrigeration oil from refrigerant gas, a four-way switching valve 23 that switches a refrigerant circulation direction, and refrigerant and outside air. An outdoor heat exchanger 24 to be exchanged, a supercooling coil 25 integrally formed with the outdoor heat exchanger 24, an outdoor expansion valve (EEVH) 26 for heating, a receiver 27 for storing liquid refrigerant, a liquid From the supercooling heat exchanger 28 that supercools the refrigerant, the supercooling expansion valve (EEVSC) 29 that controls the amount of refrigerant that is diverted to the supercooling heat exchanger 28, and the refrigerant gas that is drawn into the compressor 21 The accumulator 30 which isolate | separates a liquid component and makes the compressor 21 suck | inhale only the gas component, the gas side operation valve 31, and the liquid side operation valve 32 are provided.

  The respective devices on the outdoor unit 2 side are connected in a known manner via refrigerant pipes such as a discharge pipe 33A, a gas pipe 33B, a liquid pipe 33C, a gas pipe 33D, a suction pipe 33E, and a subcooling branch pipe 33F. The outdoor refrigerant circuit 34 is configured. The outdoor unit 2 is provided with an outdoor fan 35 that blows outside air to the outdoor heat exchanger 24. Further, between the oil separator 22 and the suction pipe 33E of the compressor 21, an oil return circuit for returning the refrigeration oil separated from the discharged refrigerant gas in the oil separator 22 to the compressor 21 by a predetermined amount. 36 is provided.

  The gas side pipe 4 and the liquid side pipe 5 are refrigerant pipes connected to the gas side operation valve 31 and the liquid side operation valve 32 of the outdoor unit 2, and are connected to the outdoor unit 2 and to it during installation on site. The length is set according to the distance between the indoor units 7A and 7B. An appropriate number of branching devices 6 are provided in the middle of the gas side piping 4 and the liquid side piping 5, and an appropriate number of indoor units 7 </ b> A and 7 </ b> B are connected via the branching devices 6. Thereby, one sealed refrigeration cycle 3 is configured.

  The indoor units 7A and 7B are configured to exchange indoor air through the indoor heat exchanger 71 for heat exchange between the refrigerant and the indoor air to be used for indoor air conditioning, an indoor expansion valve (EEVC) 72 for cooling, and the indoor heat exchanger 71. An indoor fan 73 that is circulated, and is connected to the branching device 6 via the indoor branch gas side pipes 4A and 4B and the branch liquid side pipes 5A and 5B.

In the multi-air conditioner 1, the cooling operation is performed as follows.
The high-temperature and high-pressure refrigerant gas compressed by the compressor 21 is discharged to the discharge pipe 33A, and the oil separator 22 separates the refrigerating machine oil contained in the refrigerant. Thereafter, the refrigerant gas is circulated to the gas pipe 33B side by the four-way switching valve 23, and heat is exchanged with the outside air blown by the outdoor fan 35 in the outdoor heat exchanger 24 to be condensed and liquefied. The liquid refrigerant is further cooled by the supercooling coil 25, passes through the outdoor expansion valve 26, and is temporarily stored in the receiver 27.

  The liquid refrigerant whose circulation amount has been adjusted by the receiver 27 is partly divided into the subcooling branch pipe 33F in the process of being circulated through the supercooling heat exchanger 28 via the liquid pipe 33C. (EEVSC) 29 is heat-exchanged with the refrigerant adiabatically expanded to give a degree of supercooling. This liquid refrigerant is led out from the outdoor unit 2 to the liquid side pipe 5 via the liquid side operation valve 32, and the liquid refrigerant led out to the liquid side pipe 5 is further branched into the indoor units 7A and 7B by the branching device 6. The flow is divided into the liquid side pipes 5A and 5B.

  The liquid refrigerant divided into the branch liquid side pipes 5A and 5B flows into the indoor units 7A and 7B, is adiabatically expanded by the indoor expansion valve (EEVC) 72, becomes a gas-liquid two-phase flow, and the indoor heat exchanger 71. Is flowed into. In the indoor heat exchanger 71, the indoor air circulated by the indoor fan 73 and the refrigerant are heat-exchanged, and the indoor air is cooled and provided for indoor cooling. On the other hand, the refrigerant is gasified, reaches the branching device 6 through the branch gas side pipes 4A and 4B, and is merged with the refrigerant gas from the other indoor units in the gas side pipe 4.

  The refrigerant gas merged in the gas side pipe 4 returns to the outdoor unit 2 again, reaches the suction pipe 33E through the gas side operation valve 31, the gas pipe 33D, and the four-way switching valve 23, and merges with the refrigerant gas from the branch pipe 33F. Then, it is introduced into the accumulator 30. In the accumulator 30, the liquid component contained in the refrigerant gas is separated, and only the gas component is sucked into the compressor 21. This refrigerant is compressed again in the compressor 21, and the cooling operation is performed by repeating the above cycle.

On the other hand, the heating operation is performed as follows.
The high-temperature and high-pressure refrigerant gas compressed by the compressor 21 is discharged to the discharge pipe 33A, and after the refrigerating machine oil contained in the refrigerant is separated by the oil separator 22, the four-way switching valve 23 causes the gas pipe 33D side. It is circulated in. This refrigerant is led out from the outdoor unit 2 through the gas side operation valve 31 and the gas side pipe 4, and is further introduced into the indoor units 7A and 7B through the branching unit 6 and the indoor branching gas side pipes 4A and 4B. .

  The high-temperature and high-pressure refrigerant gas introduced into the indoor units 7A and 7B is heat-exchanged with the indoor air circulated through the indoor fan 73 in the indoor heat exchanger 71, and the indoor air is heated and used for indoor heating. The The liquid refrigerant condensed in the indoor heat exchanger 71 reaches the branching device 6 through the indoor expansion valve (EEVC) 72 and the branch liquid side pipes 5A and 5B, and is merged with the refrigerant from other indoor units. It returns to the outdoor unit 2 through the side pipe 5. During heating, in the indoor units 7A and 7B, the refrigerant outlet temperature (hereinafter referred to as heat exchange outlet temperature) or the refrigerant subcooling degree of the indoor heat exchanger 71 functioning as a condenser becomes the control target value. As will be described later, the opening degree of the indoor expansion valve (EEVC) 72 is controlled.

  The refrigerant that has returned to the outdoor unit 2 reaches the supercooling heat exchanger 28 via the liquid side operation valve 32 and the liquid pipe 33C, and is given supercooling as in the case of cooling, and then flows into the receiver 27. Once stored, the amount of circulation is adjusted. This liquid refrigerant is supplied to the outdoor expansion valve (EEVH) 26 via the liquid pipe 33C, and is adiabatically expanded there, and then flows into the outdoor heat exchanger 24 through the supercooling coil 25.

  In the outdoor heat exchanger 24, heat is exchanged between the outside air blown from the outdoor fan 35 and the refrigerant, and the refrigerant absorbs heat from the outside air and is evaporated and gasified. This refrigerant is merged with the refrigerant from the subcooling branch pipe 33F from the outdoor heat exchanger 24 via the gas pipe 33B, the four-way switching valve 23, and the suction pipe 33E, and is introduced into the accumulator 30. In the accumulator 30, the liquid component contained in the refrigerant gas is separated, and only the gas component is sucked into the compressor 21 and compressed again in the compressor 21. The heating operation is performed by repeating the above cycle.

  In the multi-air conditioner 1, a plurality of indoor units 7A and 7B are usually installed at different places, and particularly when installed at different levels in a building, the space between the plurality of indoor units 7A and 7B. There may be a large difference in height. For this reason, during the heating operation, the liquid refrigerant condensed in the indoor heat exchanger 71 accumulates in the indoor units 7A and 7B installed below due to the influence of gravity, thereby reducing the heating capacity and causing inconvenience. May fall into heating. In order to prevent such unheating, this embodiment employs the following means.

  The outdoor unit 2 and the indoor units 7A and 7B are provided with an outdoor control unit 40 and an indoor control unit 50 that can communicate with each other. Each indoor unit 7A, 7B is provided with a remote controller 60 for performing a driving operation. Although a wired remote controller is shown here, a wireless remote controller may be used.

  The outdoor control unit 40 appropriately controls the rotational speed of the compressor 21, the opening degree of the outdoor expansion valve 26, and the like based on control information from the indoor control unit 50 and input information from the outdoor air temperature sensor 41 and the high-pressure sensor 42 and the like. In addition, the four-way switching valve 23 is operated to switch between cooling and heating. The outdoor control unit 40 is configured to control the high pressure to the heating target high pressure HP based on the detection value of the high pressure sensor 42 during the heating operation.

  The indoor control unit 50 provides necessary control information to the outdoor control unit 40 based on input information from the intake air temperature sensor 51, the blown air temperature sensor 52, the heat exchange temperature sensor 53, the heat exchange outlet temperature sensors 54 and 55, and the like. While transmitting, it is comprised so that the opening degree of the indoor expansion valve 72, the air volume by the indoor fan 73, etc. may be controlled suitably. Further, during the heating operation, the indoor control unit 50 uses the detection value of the heat exchange outlet temperature sensor 55 and / or the high pressure sensor 42 to set the heat exchange outlet temperature of the indoor heat exchanger 71 or the refrigerant supercooling degree as a control target value. Thus, the opening degree of the indoor expansion valve (EEVC) 72 is controlled.

  Further, the outdoor control unit 40 has 7 segments for setting a target heat exchange outlet temperature or a target refrigerant subcooling degree used for controlling the indoor expansion valves 72 of the plurality of indoor units 7A and 7B installed with a height difference. A control target value setting unit 43 is provided. The indoor control unit 50 controls the control target value (target heat exchange outlet temperature or target refrigerant subcooling degree) set via the control target value setting unit 53. Is configured to control the opening of the indoor expansion valve 72.

  Next, how to set the control target value of the heat exchange outlet temperature control so that liquid refrigerant does not accumulate under the influence of gravity in the indoor units 7A and 7B installed below during the heating operation will be described with reference to FIG. This will be described in detail with reference to schematic diagrams. In FIG. 2, the height difference between the outdoor unit 2 and the indoor unit 7A, the indoor unit 7B, and the indoor unit 7C is 40 m, 30 m, and 20 m, respectively, and the height difference between the indoor unit 7A and the indoor unit 7B is 10 m ( 40m-30m), and an installation example in which the height difference between MAX indoor units is 20m (40m-20m) is shown.

Here, the general formula is as follows.
MAX saturation temperature difference = saturation temperature of lowermost indoor unit−saturation temperature of uppermost indoor unit MAX difference between indoor units = highest indoor unit height−lowermost indoor unit height Lowermost indoor unit target heat exchange outlet temperature = Target heat exchange outlet temperature initial value Uppermost indoor unit target heat exchange outlet temperature = target heat exchange outlet temperature initial value-MAX saturation temperature difference Intermediate indoor unit target heat exchange outlet temperature = target heat exchange outlet temperature initial value-MAX saturation temperature difference × (Altitude difference between the lowest indoor unit and the corresponding indoor unit / height difference between MAX indoor units)

(A) Calculation of target heat exchange outlet temperature when only head difference is considered Head difference ΔP due to height difference is:
ΔP = ρgΔH
= 1000kg / m ³ × 10m / s ² × 10m
= 0.1 MPa
However, it is assumed that the density ρ = 1000 kg / m ³ and the gravitational acceleration g = 10 m / s ² (in this case, the indoor unit 7A is applied with the pressure of the indoor unit 7B + 0.1 MPa (liquid head difference)). The pressure of the indoor unit 7B is -0.1 MPa (liquid head difference) is applied to 7C).

From the thermophysical properties of the refrigerant, the pressure of the indoor unit 7A, the indoor unit 7B, and the indoor unit 7C is
Pressure of indoor unit 7A = pressure of indoor unit 7B + 0.1 MPa (liquid head difference)
Pressure of indoor unit 7B Pressure of indoor unit 7C = Pressure of indoor unit 7B−0.1 MPa (liquid head difference)
When the respective pressure saturation temperatures are obtained, for example,
Pressure of indoor unit 7B = 2.7 MPaG → saturation temperature = 46 ° C.
Pressure of indoor unit 7A = 2.7 + 0.1 = 2.8 MPaG → saturation temperature = 48 ° C.
Pressure of indoor unit 7C = 2.7−0.1 = 2.6 MPaG → saturation temperature = 44 ° C.
It becomes.

In order to eliminate the saturation temperature difference between the indoor units 7A to 7C, if a temperature difference is provided to the target heat exchange outlet temperature of each indoor unit 7A to 7C,
The target heat exchange outlet temperature of each indoor unit 7A to 7C is
If the target heat exchange outlet temperature initial value = 40 ° C,
Target heat exchange outlet temperature of indoor unit 7A = 40 ° C
Target heat exchange outlet temperature of indoor unit 7B = 40− (48−44) / (10/20) = 38 ° C.
Target heat exchange outlet temperature of indoor unit 7C = 40− (48−44) = 36 ° C.
It becomes. Accordingly, as shown in FIG. 3A, the target heat exchange outlet temperature is set in each of the indoor units 7A to 7C, and the opening degree of the indoor expansion valve 72 of the indoor units 7B and 7C installed above. Becomes squeezed, and the accumulation of refrigerant in the indoor unit 7A installed below can be prevented.

In the above general formula,
New target heat exchange outlet temperature initial value = target heat exchange outlet temperature initial value + MAX saturation temperature difference / 2
Lowermost indoor unit new target heat exchange outlet temperature = New target heat exchange outlet temperature initial value Uppermost indoor unit new target heat exchange outlet temperature = New target heat exchange outlet temperature initial value-MAX saturation temperature difference Intermediate indoor unit new target heat exchange Outlet temperature = New target heat exchange outlet temperature initial value-MAX saturation temperature difference x (height difference between the lowest indoor unit and the corresponding indoor unit / height difference between MAX indoor units)
Then,
The saturation temperature difference between the indoor unit 7A and the indoor unit 7B is 48−46 = 2 deg.
The saturation temperature difference between the indoor unit 7A and the indoor unit 7C is 48−44 = 4 deg.
It becomes.

Here, assuming that the target heat exchange outlet temperature initial value = 40 ° C.,
New target heat exchange outlet temperature initial value = 40 + (48−44) / 2 = 42 ° C.
New target heat exchange outlet temperature of indoor unit 7A = 42 ° C
New target heat exchange outlet temperature of indoor unit 7B = 42 ° C .− (48−44) × (10/20) = 40 ° C.
New target heat exchange outlet temperature of indoor unit 7C = 42 ° C .− (48−44) = 38 ° C.
It becomes. Thereby, the opening degree of the indoor expansion valve 72 of the indoor units 7B and 7C installed on the upper side becomes narrow, and the accumulation of refrigerant in the indoor unit 7A installed on the lower side can be prevented. In this case, since the target heat exchange outlet temperature can be made higher than that in the above case, the temperature of the air blown from each of the indoor units 7A to 7C can be made higher.

(B) Calculation of target heat exchange outlet temperature when head difference and piping pressure loss are taken into account Head difference ΔP due to height difference is the same as above.
ΔP = ρgΔH
= 1000kg / m ³ × 10m / s ² × 10m
= 0.1 MPa
However, it is assumed that density ρ = 1000 kg / m ³ and gravitational acceleration g = 10 m / s ² (the indoor unit 7A is subjected to the pressure of the indoor unit 7B + 0.1 MPa liquid head pressure, and the indoor unit 7C includes the indoor unit 7B Pressure -0.1 MPa liquid head pressure is applied).

Furthermore, when the pipe length is indoor unit 7A> indoor unit 7B, the pressure loss ΔP of the liquid pipe 5A between the indoor unit 7A and the indoor unit 7B is
ΔP = λ · L / d · ρv 2/2
= 0.016 × 10m / 11.1mm × 1000kg / m 3 × (2m / s) 2/2
= 0.03 MPa
However, λ = 0.016, density ρ = 1000 kg / m ³ , pipe flow velocity v = 2 m / s, gravity acceleration g = 10 m / s ² , pipe length difference L of indoor unit 7A and indoor unit 7B = 10 m, pipe Assume that the inner diameter d = 11.1 mm. The pipe flow velocity v was calculated from the displacement of the compressor 21, the number of rotations, and the refrigerant heat physical properties.

From the thermophysical properties of the refrigerant, the pressure of the indoor unit 7A and the indoor unit 7B is
Pressure of indoor unit 7A = pressure of indoor unit 7B + 0.1 MPa (liquid head difference) +0.03 MPa (liquid pipe pressure loss)
When it becomes the pressure of the indoor unit 7B and the respective pressure saturation temperatures are obtained, for example,
Pressure of indoor unit 7B = 2.7 MPaG → saturation temperature = 46 ° C.
Pressure of indoor unit 7A = 2.7 + 0.13 = 2.83 MPaG → saturation temperature = 49 ° C.
It becomes.

In order to eliminate the above saturation temperature difference, if a temperature difference is provided in the target heat exchange outlet temperature of the indoor unit 7A and the indoor unit 7B,
The target heat exchange outlet temperature of the indoor unit 7A and the indoor unit 7B is
If the target heat exchange outlet temperature initial value = 40 ° C,
Target heat exchange outlet temperature of indoor unit 7A = 40 ° C
Target heat exchange outlet temperature of indoor unit 7B = 40− (49−46) = 37 ° C.
It becomes. As a result, the opening of the indoor expansion valve 72 of the indoor unit 7B installed at the upper side becomes throttled, and the accumulation of refrigerant in the indoor unit 7A installed at the lower side can be prevented.

The saturation temperature difference between the indoor unit 7A and the indoor unit 7B is 49−46 = 3 deg.
If the target heat exchange outlet temperature initial value = 40 ° C,
New target heat exchange outlet temperature initial value = 40 + (49−46) /2=41.5° C.
New target heat exchange outlet temperature of indoor unit 7A = 41.5 ° C
New target heat exchange outlet temperature of indoor unit 7B = 41.5 ° C .− (49−46) = 38.5 ° C.
It becomes. As a result, the opening of the indoor expansion valve 72 of the indoor unit 7B installed at the upper side becomes throttled, and the accumulation of refrigerant in the indoor unit 7A installed at the lower side can be prevented. Further, since the target heat exchange outlet temperature can be made higher than in the above case, the temperature of the air blown from each of the indoor units 7A to 7C can be made higher.

  In addition, when the multi air conditioner 1 is actually installed, the control target value calculated above is appropriately calculated by a contractor according to the situation of the installation site, and the outdoor control unit of the outdoor unit 2 By setting in the control target value setting unit 43 provided in 40, for example, as shown in FIG. 3A, it can be set as the control target value of each indoor unit 7A to 7C. As a result, in the multi-air conditioner 1, during the heating operation, the outlet refrigerant temperature of the indoor heat exchanger 72 detected by the heat exchange outlet temperature sensor 55 becomes the target heat exchange outlet temperature set as described above. Then, the opening degree of the indoor expansion valve 72 is controlled via the indoor control unit 50.

  As described above, according to this embodiment, even when a plurality of indoor units 7A to 7C are installed with a large difference in elevation, each indoor unit 7A to 7C has an appropriate target heat exchange outlet temperature corresponding to the difference in elevation. Based on this, the indoor expansion valve 72 of each indoor unit 7A to 7C is controlled, so that the opening degree of the indoor expansion valve 72 of the indoor unit 7A to 7C installed above is slightly reduced. Therefore, the accumulation of refrigerant in the indoor heat exchanger 71 of the indoor units 7A to 7C installed below can be suppressed.

  Accordingly, it is possible to prevent the heating capacity of the indoor units 7A to 7C installed below from being lowered, and to eliminate the occurrence of non-heating caused by the plurality of indoor units 7A to 7C being installed with a height difference. . Further, since the target heat exchange outlet temperature for each of the indoor units 7A to 7C can be set collectively on the outdoor unit 2 side, the setting operation of the control target value can be simplified. Furthermore, since an appropriate target heat exchange outlet temperature can be initially set when the multi-air conditioner 1 is installed, it can be operated so as not to be unheated from the beginning of the operation.

  In the above, the opening degree of the indoor expansion valve 72 is controlled via the indoor control unit 50 so that the outlet refrigerant temperature of the indoor heat exchanger 72 detected by the heat exchange outlet temperature sensor 55 becomes the target heat exchange outlet temperature. However, instead of the heat exchange outlet temperature control, the high pressure pressure saturation temperature detected by the high pressure sensor 42 and the outlet refrigerant temperature of the indoor heat exchanger 72 detected by the heat exchange outlet temperature sensor 55 are used. Even when the opening degree of the indoor expansion valve 72 is controlled using the calculated refrigerant subcooling degree as a control target value, the target refrigerant subcooling degree is appropriately calculated and is used as the control target value for the outdoor unit 2. By setting in the setting unit 43, similarly to the above, it is possible to prevent a decrease in the heating capacity of the indoor units 7A to 7C installed below, and to install the plurality of indoor units 7A to 7C with a height difference. It is possible to eliminate the occurrence of non-heating due to.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
In the present embodiment, compared to the first embodiment described above, the outdoor control unit 40 is provided with a height difference input unit 44 and a control target value calculation unit 45 that calculates a target heat exchange outlet temperature based on the input value. The point is different. Since other points are the same as those in the first embodiment, description thereof will be omitted.
In this embodiment, as shown in FIG. 1, instead of the control target value setting unit 43, an input for inputting a height difference between the plurality of indoor units 7 </ b> A, 7 </ b> B and the outdoor unit 2 to the outdoor control unit 40. And the target heat exchange outlet temperature or the target refrigerant subcooling degree used for controlling the indoor expansion valves 72 of the plurality of indoor units 7A and 7B installed with a difference in height based on the input value from the input unit 45 And a control target value calculation unit 46 for calculating.

  That is, in this embodiment, instead of the contractor calculating the target heat exchange outlet temperature or the target refrigerant subcooling degree on the site and setting it in the control target value setting unit 43, the contractor can set the multi air conditioner 1. By inputting the height difference between the plurality of indoor units 7A and 7B and the outdoor unit 2 measured at the installation site from the input unit 44, the control target value calculation unit 45 causes the height difference between the indoor units 7A and 7B. And the target heat exchange outlet temperature or the target refrigerant subcooling degree is automatically calculated according to the above general formula, and as shown in FIG. 3 (A), the indoor control of each indoor unit 7A, 7B is calculated. The unit 50 is configured to be set.

  Thus, by providing the outdoor control unit 40 with the elevation difference input unit 44 and the control target value calculation unit 45 that calculates the target heat exchange outlet temperature or the target refrigerant subcooling degree based on the input value, Even when multiple indoor units 7A and 7B are installed with a height difference, the target heat exchange outlet temperature or the target refrigerant supercooling degree corresponding to the indoor unit 7A and 7B can be automatically calculated by inputting the height difference measurement data. It becomes possible to set. Then, using this as a control target value, the opening degree of the indoor expansion valve 72 can be subjected to heat exchange outlet temperature control or supercooling degree control.

  Therefore, also according to this embodiment, the same effect as that of the first embodiment described above can be obtained. Further, in the present embodiment, since the target heat exchange outlet temperature or the target refrigerant subcooling degree can be automatically calculated, there is no need to perform troublesome calculations at the site, and the installation work of the multi air conditioner 1 can be performed efficiently. Can be

[Other Embodiments]
Next, other embodiments of the present invention will be described below.
(1) In the above embodiment, by inputting the height difference information, as shown in FIG. 3A, the target heat exchange outlet temperature or the target refrigerant subcooling degree is set as the control target value of each indoor unit 7A to 7C. As shown in FIG. 3B, the temperature difference is calculated based on the control target value of the indoor unit 7A installed at the lowermost position. May be input. Also by this, the same effect as the above can be obtained.

(2) In the above embodiment, the control target value calculation unit 46 calculates the height difference between the indoor units 7A to 7C from the height difference between the plurality of indoor units 7A to 7C and the outdoor unit 2, and Based on this, the target heat exchange outlet temperature or the target refrigerant subcooling degree of each indoor unit 7A to 7C is calculated. As shown in FIG. 3C, between the indoor units 7A to 7C that are thermo-on. The target heat exchange outlet temperature, the target refrigerant supercooling degree, or the temperature difference from the control target value of the lowest indoor unit that is thermo-ON may be calculated and set.
According to this, it is only necessary to calculate the target heat exchange outlet temperature or the target refrigerant subcooling degree only between the indoor units 7A to 7C that are thermo-ON, and increase the target heat exchange outlet temperature or the target refrigerant subcooling degree as a whole. be able to. For this reason, the fall of the heating capability of indoor unit 7A thru | or 7C by which thermo-ON is carried out can be suppressed, and the improvement of heating performance can be aimed at.

(3) In the above embodiment, an example has been described in which the target heat exchange outlet temperature, the target refrigerant supercooling degree, or height difference data is set in the control target value setting unit 43 or the input unit 45 of the outdoor control unit 40. These settings can be set from a remote controller 60 provided in each indoor unit 7A to 7C.
In this way, during the heating operation, the control target value for controlling the indoor expansion valve 72 can be set from the remote controllers of the plurality of indoor units 7A to 7C, so that the target heat exchange outlet temperature for each of the indoor units 7A to 7C or Since the target refrigerant supercooling degree can be set not only collectively on the outdoor unit 2 side but also from the remote controller 60 of each indoor unit 7A to 7C, the target corresponding to the height difference of the indoor units 7A to 7C The convenience of setting the heat exchange outlet temperature or the target refrigerant supercooling degree can be further improved.

  (4) In the above embodiment, the target heat exchange outlet temperature or the target refrigerant subcooling degree for controlling the indoor expansion valve 72 during the heating operation is set in correspondence with the plurality of indoor units 7A to 7C installed with a difference in elevation. In the outdoor control unit 40, when a new control target value is set corresponding to the height difference of the plurality of indoor units 7A to 7C, the outdoor control unit 40 sets the heating target high pressure. It is good also as a structure which controls the compressor 21 so that HP may be raised by a fixed value and it may become the heating target high pressure HP by which the high pressure increased by the fixed value based on the detection value of the high pressure sensor 42.

  As described above, when a new target heat exchange outlet temperature or a target refrigerant subcooling degree for controlling the indoor expansion valve 72 is set, the heating target high pressure HP is increased by a certain value to thereby reduce the room installed below. It is possible not only to suppress the accumulation of refrigerant in the indoor heat exchanger 71 of the machines 7A to 7C, but also to suppress accumulation of liquid refrigerant in the indoor heat exchanger 71 by increasing the heating target high pressure by a certain value. Therefore, it is possible to more reliably eliminate the occurrence of non-heating caused by the installation of the plurality of indoor units 7A to 7C with a difference in elevation, and the capability of being increased by increasing the high pressure. Degradation can be minimized.

  (5) In the above embodiment, the opening degree of the indoor expansion valve 72 is calculated by the indoor control unit 50 of each indoor unit 7A to 7C and commanded to each indoor expansion valve 72, but the outdoor control unit 40 side It may be configured to calculate and to instruct from the outdoor control unit 40 side, and this can also provide the same effects as described above.

  In addition, this invention is not limited to the invention concerning the said embodiment, In the range which does not deviate from the summary, it can change suitably. For example, the above-described calculation method of the target heat exchange outlet temperature or the target refrigerant subcooling degree is merely an example, and needless to say, it is not limited to this. Further, in the embodiment shown in FIG. 1, the indoor control unit 50 and the remote controller 60 are shown only in the indoor unit 7A, but the indoor control unit 50 and the remote control 60 are similarly provided in other indoor units. Needless to say.

DESCRIPTION OF SYMBOLS 1 Multi air conditioner 2 Outdoor unit 4, 4A, 4B Gas side piping 5, 5A, 5B Liquid side piping 7A, 7B, 7C Indoor unit 21 Compressor 24 Outdoor heat exchanger 26 Outdoor expansion valve 40 Outdoor control part 43 Control target Value setting unit 45 Input unit 46 Control target value calculation unit 50 Indoor control unit 60 Remote control 71 Indoor heat exchanger 72 Indoor expansion valve

Claims (6)

A plurality of outdoor units having a compressor, an outdoor heat exchanger and an outdoor expansion valve, and an indoor heat exchanger and an indoor expansion valve, which are connected in parallel to the outdoor unit via a gas side pipe and a liquid side pipe Each of the outdoor unit and the indoor unit is provided with an outdoor control unit and an indoor control unit that are communicable with each other. During heating operation, either the indoor control unit or the outdoor control unit However, in the multi-type air conditioner configured to control the opening of the indoor expansion valve so that the heat exchange outlet temperature of the indoor unit or the refrigerant supercooling degree becomes a target value,
The outdoor control unit includes a control target value setting unit for setting a target heat exchange outlet temperature or a target refrigerant subcooling degree used for controlling the indoor expansion valves of the plurality of indoor units installed with a height difference. Provided,
Each of the indoor units corresponding to an initial value of the target heat exchange outlet temperature or an initial value of the target refrigerant supercooling degree is set according to the head difference and / or pipe pressure loss and refrigerant physical properties when installed. Pressure saturation temperature is calculated, the new target heat exchange outlet temperature or the target refrigerant subcooling degree is calculated, and set in the control target value setting unit,
In either the indoor control unit or the outdoor control unit, the opening degree of the indoor expansion valve is controlled based on the control target value set by the control target value setting unit. Multi air conditioner. A plurality of outdoor units having a compressor, an outdoor heat exchanger and an outdoor expansion valve, and an indoor heat exchanger and an indoor expansion valve, which are connected in parallel to the outdoor unit via a gas side pipe and a liquid side pipe Each of the outdoor unit and the indoor unit is provided with an outdoor control unit and an indoor control unit that are communicable with each other. During heating operation, either the indoor control unit or the outdoor control unit However, in the multi-type air conditioner configured to control the opening of the indoor expansion valve so that the heat exchange outlet temperature of the indoor unit or the refrigerant supercooling degree becomes a target value,
The outdoor control unit includes an input unit that inputs a height difference between the plurality of indoor units and the outdoor unit, and the plurality of indoor units that are installed with a height difference based on an input value from the input unit. A control target value calculation unit for calculating a target heat exchange outlet temperature or a target refrigerant subcooling degree used for control of each of the indoor expansion valves is provided,
At the time of installation, the height difference is input to the input unit with respect to the initial value of the target heat exchange outlet temperature or the initial value of the target refrigerant supercooling degree, and the control target value calculation unit based on the input value From the head difference due to the height difference and / or the pipe pressure loss and the refrigerant physical properties, obtain the pressure saturation temperature of each indoor unit according to it, calculate the new target heat exchange outlet temperature or the target refrigerant subcooling degree,
In either the indoor control unit or the outdoor control unit, the opening degree of the indoor expansion valve is controlled based on the control target value calculated by the control target value calculation unit. Multi air conditioner.   The input unit replaces the height difference between the plurality of indoor units and the outdoor unit with a temperature difference between a target heat exchange outlet temperature or a target refrigerant subcooling degree with respect to the indoor unit installed at the lowest position. The multi-air conditioner according to claim 2, wherein the multi-air conditioner is an input unit for inputting.   The control target value calculation unit calculates a difference in height between the indoor units from a difference in height between the plurality of indoor units and the outdoor unit, and based on the calculated difference in target heat exchange temperature between the thermo-on indoor units Alternatively, the multi-air conditioner according to claim 2, wherein the target refrigerant supercooling degree can be calculated.   The multi-air conditioner according to any one of claims 1 to 4, wherein the control target value can be set from a remote controller of the plurality of indoor units. The outdoor control unit is configured to increase a heating target high pressure by a certain value when a new control target value is set corresponding to a height difference between the plurality of indoor units. The multi air conditioner according to claim 1 or 2.

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