JPH08121902A - Air conditioning device - Google Patents

Abstract

PURPOSE: To carry out cooling operation or heating operation for each air- conditioning zone at a low cost. CONSTITUTION: A plurality of indoor equipment form 50A to 50C are connected to outdoor equipment 30 side by side by way of a branch unit 40. The air supply of the indoor equipment is led to a plurality of air conditioning zones by way of a duct where the amount of air is varied by a VAV unit. The branch unit 40 is provided with a supercooling heat exchanger 12 and solenoid valves 13A to 13C and 23A to 23C which enables selection of cooling operation or heating operation by changing-over; the outdoor equipment is provided with a supercooling heat exchanger 4 where a flow control valve 25 and an expansion valve 7 are installed to the liquid pipe side. Flow control valves 14A to 14C and expansion valves 15A to 15C are installed to the liquid pipe of the indoor equipment. This construction makes it possible to execute cooling operation and heating operation arbitrarily to comply with demands from each air conditioning zone, and what is more, to provide a stabilized air-conditioning without any change in diffused air temperature, even if the flow rate of air is changed. During simultaneous operation, both cooling and heating, a great energy-saving is possible since heat energy is transferred between the indoor equipment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-type air conditioner comprising one outdoor unit and a plurality of indoor units and used for air conditioning of a building or the like.

[0002]

2. Description of the Related Art For air conditioning of buildings and the like, air conditioning units such as air handling units and fan coils are generally used with cold and hot water as a heat source. However, in recent years, the water quality has been severely deteriorated, which causes many problems such as corrosion of pipes, and there is a demand for refraining from using water as much as possible. As a response to such a demand, for example, a heat pump multi-method using a refrigerant as a direct heat source, a VAV package method, etc. have been proposed. On the other hand, air conditioning in recent years has diversified and is no longer as simple as cooling operation in summer and heating operation in winter. That is, in a building or the like, there are cases where it is desired to simultaneously perform the cooling operation and the heating operation in the air conditioning system depending on the season, the direction and position of the room, the load of the OA equipment, and the like. For example, it may be desired to perform cooling operation in the interior zone of the building and heating operation in the perimeter zone.

In some cases, heating operation is required in the morning and evening in the middle of spring and autumn, and cooling operation is required in the daytime. In this case, the switching timing between the cooling operation and the heating operation differs depending on the direction of the air conditioning zone, and although the condition to switch to the cooling operation is reached on the south side, the heating operation may still need to be continued on the north side. Further, in a place with a large load such as OA equipment, it may be necessary to perform cooling operation all day even in winter. Therefore, as a countermeasure against this, there is a case where an air-conditioning system using an air handling unit having two heat sources, a cold heat source and a hot heat source, called a dual duct system is adopted.

[0004]

However, the dual duct system has a drawback that the facility cost and the operating cost are high. Furthermore, since the waste heat of the two heat sources has been discarded respectively, it goes against energy conservation. Further, in the heat pump multi-system capable of simultaneous cooling and heating, an indoor unit is required for each air conditioning zone because the blowing temperature is changed according to the load. Therefore, a large number of indoor units are installed in the living area, and their maintainability is extremely low. In addition, since this is an indoor air circulation type air conditioning system, there is a problem in that an external air treatment device must be newly installed for each of a large number of indoor units for the outdoor air treatment function, resulting in a high equipment cost.

Further, during the simultaneous cooling and heating operation, the refrigerant cannot be properly distributed between a plurality of indoor units of the same mode, or between the indoor unit and the outdoor unit of the same mode, and the capacity control of the compressor is not sufficient. Therefore, the temperature of the blown air is also different for each indoor unit.Therefore, when the temperature reaches the set temperature, the refrigerant control valve of the indoor unit is closed and the function is stopped, and it is said that room temperature controllability is good. It's hard.

On the other hand, in the case of the VAV package system,
Since the outdoor unit and the indoor unit are concentrated in one place, the maintainability is good, and the blown air temperature can be controlled to be constant. However, all indoor units can be operated only in either cooling operation or heating operation, and there is a drawback that changing the operation mode requires a certain procedure and time. In addition, the direction and position of the air conditioning zone in the building, O
For multiple air conditioning zones with different loads due to uneven distribution of equipment A, etc., it is necessary to install separate outdoor units and indoor units, so the number of air conditioners also increases,
Therefore, the installation space is increased.

Therefore, in order to perform the cooling operation and the heating operation individually and simultaneously in accordance with the required load in each air conditioning zone, it is conceivable to combine the cooling / heating simultaneous operation type heat pump multi system and the VAV package system. . However, various problems occur even if they are simply applied in layers. That is, the cooling / heating simultaneous operation type heat pump multi system basically controls the blown air temperature according to the load on the assumption that the air volume is constant. On the other hand, the VAV package method controls the capacity of the compressor so that the temperature of the blown air becomes constant,
The supplied air volume is variable according to the load of each air conditioning zone to maintain a predetermined room temperature.However, even if the total air volume of an indoor unit decreases, the air conditioning load of all air conditioning zones decreases. Does not mean.

On the other hand, in the simultaneous cooling / heating simultaneous heat pump multi system, the temperature of blown air cannot be controlled by simply controlling the capacity of the compressor. This is because in the cooling / heating simultaneous operation type heat pump multi-system, the refrigerant piping distances from the outdoor unit to the plurality of indoor units are different, and the pressure loss is proportional to the square of the refrigerant flow velocity. This is because the refrigerant pressure distribution reaching the indoor units changes significantly and the refrigerant flow rate of each indoor unit also changes.

In the above VAV package system,
Since the air conditioning load of each air conditioner zone is different, it is necessary to make the blown air temperature different for each air conditioner. At this time, if the capacity of the compressor is controlled to change the temperature of air blown out from one indoor unit based on the cooling / heating simultaneous operation type heat pump multi system, the temperature of air blown out from other indoor units changes as described above. Will be done. Therefore, especially when trying to control the interior of multiple zones individually using ducts, there is a problem that the room temperature that was comfortable until now changes without touching anything depending on the air conditioning zone. It can happen. Similarly, indoor units will interfere with each other,
It is not preferable because it is difficult to control the temperature of the blown air.

Further, in actual air conditioning, when the air conditioning load in all air conditioning zones is reduced and, for example, the majority of VAV units are in the minimum ventilation state during cooling operation, the indoor unit changes the blown air temperature. By raising it, the VAV unit is returned to the control range so that comfortable air conditioning is maintained, and when the blowing air temperature is insufficient for the required load of all air conditioning zones, the blowing air temperature can be lowered. desirable.

Therefore, in view of the above-mentioned problems of the prior art, the present invention provides an air conditioner having one outdoor unit and a plurality of indoor units without requiring a high equipment cost and in each air conditioning zone. It is an object of the present invention to provide an air conditioner capable of individually performing a cooling operation or a heating operation according to a load, and further an air conditioner capable of individually changing an air volume and excellent in energy saving.

[0012]

For this reason, the present invention provides a heat exchanger, an expansion valve attached to the heat exchanger, a flow rate adjusting means provided in front of the expansion valve, and the flow rate adjusting means. One outdoor unit having first control means for controlling, a heat exchanger, an expansion valve attached to the heat exchanger, a flow rate adjusting means provided in front of the expansion valve, and the flow rate adjusting means A plurality of indoor units connected in parallel to the outdoor unit by a refrigerant pipe forming a liquid pipe of a refrigeration cycle, a high-pressure gas pipe, and a low-pressure gas pipe, and each indoor unit. The air blown to the plurality of air conditioning zones by the ducts, and the VAV unit provided in the duct for each air conditioning zone and the gas pipe connected to the heat exchanger of the outdoor unit are directed to the heat exchanger of the outdoor unit. Choice of high-pressure gas pipe or low-pressure gas pipe And a second switching means capable of selectively connecting the gas pipe connected to the heat exchanger of each indoor unit to the high-pressure gas pipe or the low-pressure gas pipe. The respective indoor units are selectively controlled individually to the cooling operation or the heating operation, and the room temperature of each air conditioning zone is configured to be controlled by the change in the air volume by the VAV unit.

The second control means of the indoor unit controls the indoor unit so that the supercooling degree of the refrigerant in the expansion valve of the indoor unit during cooling operation becomes a value determined according to the load of the indoor unit. It is desirable to control the flow rate adjusting means of the indoor unit so that the degree of supercooling of the refrigerant discharged from the heat exchanger of the indoor unit becomes constant during the heating operation. Further, the first control means of the outdoor unit, when the heat exchanger of the outdoor unit acts as a condenser, the degree of subcooling of the refrigerant exiting the heat exchanger of the outdoor unit depends on the load of the heat exchanger. The flow rate adjusting means of the outdoor unit is controlled so that the determined value is reached.When the heat exchanger of the outdoor unit acts as an evaporator, the degree of supercooling of the refrigerant in the expansion valve of the outdoor unit causes the heat exchange of the outdoor unit. It is desirable to control the flow rate adjusting means of the outdoor unit so that the value is determined according to the load of the unit.

Furthermore, when the heat exchanger of at least one of the indoor units acts as an evaporator, heat is exchanged between the liquid pipe toward the indoor unit and the low pressure gas pipe toward the outdoor unit. A first subcooling heat exchanger is preferably provided, and when the heat exchanger of the outdoor unit acts as an evaporator, between the liquid pipe and the low-pressure gas pipe that are directed to the heat exchanger of the outdoor unit, It is preferable to provide a second subcooling heat exchanger that exchanges heat between them.

[0015]

A VAV unit is provided in each duct from each indoor unit to a plurality of air conditioning zones, and the room temperature of each air conditioning zone is adjusted by changing the amount of air blown by the VAV unit. In the outdoor unit and the indoor unit, the first and second control means control the flow rate adjusting means arranged in front of each expansion valve so that the degree of supercooling corresponds to an individual load, and By selectively connecting the gas pipe of the heat exchanger of the outdoor unit to the high-pressure gas pipe or the low-pressure gas pipe, it is possible to select any of the indoor units such that the cooling operation and the heating operation are simultaneously mixed. As a result, even in a large number of air-conditioning zones, the room temperature is controlled by the VAV unit having a simple structure, and it is not necessary to individually install a large number of indoor units, which improves maintainability. Further, during the simultaneous cooling and heating operation, heat energy is transferred between the indoor units, resulting in significant energy saving.

Further, the second control means of the indoor unit sets the supercooling degree of the refrigerant to a value determined according to the load of the indoor unit during the cooling operation, and the subcooling degree during the heating operation. By controlling the flow rate adjusting means so as to be constant, the refrigerant pressure entering the expansion valve can be kept constant in each indoor unit without causing interference with other indoor units even if the blown air volume is changed. , Stable air temperature adjustment is performed. Then, the temperature of the blown air can be arbitrarily controlled as needed.

When the first subcooling heat exchanger is provided between the liquid pipes and the low pressure gas pipes which are directed to the plurality of indoor units, the control range of the flow rate by the flow rate adjusting means is expanded. further,
Second between the low pressure gas pipe and the liquid pipe that goes to the heat exchanger of the outdoor unit
When a supercooling heat exchanger is installed, the degree of superheat of the gas refrigerant entering the compressor of the outdoor unit can be increased,
The heating capacity is improved.

[0018]

1 shows the system configuration of a first embodiment of the present invention. In this embodiment, three indoor units 50A, 50B and 50C are connected in parallel to one outdoor unit 30 via a branch unit 40. Air that has undergone heat exchange from each indoor unit is ducts 47A, 47B, 47C.
Air conditioning zones ZA1, ZA2, ZB1, ZB2, Z
Guided to C. Each duct is branched appropriately according to the number of corresponding air-conditioning zones, and each VAV unit 45A,
45B, 45C, etc. are provided, and the air volume to the air conditioning zone can be changed individually.

FIG. 2 shows the refrigerant circuit of this embodiment. The three indoor units 50A, 50B, and 50C are the branch units 40.
, And is connected in parallel to the outdoor unit 30 by refrigerant pipes R1, R2, and R3 that form a liquid pipe, a low-pressure gas pipe, and a high-pressure gas pipe. The outdoor unit 30 includes a compressor 1 having a variable capacity and a heat exchanger 6. An accumulator 3 is attached to the suction side of the compressor 1, and pressure sensors 11A and 11B are provided on the discharge side and suction side pipes of the compressor 1, respectively. A blower 21 is attached to the heat exchanger 6, and temperature sensors 10A and 10B are provided at both ends, respectively.

The outdoor unit 30 further includes a subcooling heat exchanger 4
And one end of the subcooling heat exchanger 4 and the heat exchanger 6 are provided.
In the refrigerant pipe between the one ends, in order from the subcooling heat exchanger 4 side to the heat exchanger 6, an electronic flow rate adjusting valve 25, a temperature sensor 9 for detecting the refrigerant temperature, a pressure sensor 8, an electronic type. The expansion valve 7 is installed. The other end of the supercooling heat exchanger 4 is connected to the refrigerant pipe R1 via the liquid tank 27. The refrigerant pipe (gas pipe) on the other end side of the heat exchanger 6 is connected to the inlet of the heat exchange passage of the supercooling heat exchanger 4 via the solenoid valve 5A, and is also connected to the refrigerant pipe R3 via the solenoid valve 5B.
It is connected to the. The outlet of the heat exchange passage of the supercooling heat exchanger 4 is connected to the refrigerant pipe R2. Refrigerant pipe R2
Is also connected to the accumulator 3, and the refrigerant pipe R3 is connected to the discharge side of the compressor 1.

The branch unit 40 includes the subcooling heat exchanger 12. The subcooling heat exchanger 12 is connected to the liquid tank 27 of the outdoor unit 30 by the refrigerant pipe R1. In addition, the outlet of the supercooling heat exchanger 12 has indoor units 50A, 50B, 50
It is branched and connected to C. Furthermore, branch unit 4
0, solenoid valves 13A, 13B, 13C, 23A, 23
B, 23C are provided, and solenoid valves 13A, 13B, 13C
Enables the indoor units 50A, 50B, 50C to communicate with the other refrigerant pipe R2 system of the subcooling heat exchanger 12, and the solenoid valves 23A, 23B, 23C respectively provide the indoor unit 5
0A, 50B, and 50C can be communicated with the refrigerant pipe R3.

The indoor unit 50A includes a heat exchanger 18A and a blower 24A attached to the heat exchanger 18A. One end of the heat exchanger 18A is connected to the R1 system of the subcooling heat exchanger 12 of the branch unit 40, and the other end is connected to the solenoid valves 13A and 23A of the branch unit 40. In the R1 pipe on one end side of the heat exchanger 18A, an electronic flow rate adjusting valve 14A, a temperature sensor 17A for detecting a refrigerant temperature, a pressure sensor 16A, and an electronic device are arranged in this order from the subcooling heat exchanger 12 side to the heat exchanger 18A direction. Type expansion valve 15A is provided. Also, the heat exchanger 1
8A is provided with temperature sensors 22A and 26A for detecting the blown air temperature and the sucked air temperature of the indoor unit, respectively, and temperature sensors 19A and 20A are provided at both ends.

The heat is exchanged by the heat exchanger 18A, and the blower 24
The air blown by A is guided to the air conditioning zones ZA1 and ZA2 by the duct 47A as shown in FIG.
A VAV unit 4 is provided on each side of the air conditioning zone of the duct.
5A is provided so that the air volume can be changed individually.
The indoor units 50B and 50C also have the same configuration as that of the indoor unit 50A, and hereinafter, reference numerals B and C are attached respectively.

FIG. 3 shows a control device in the above indoor unit and outdoor unit. The control device is composed of a microcomputer and its peripherals in both the indoor unit and the outdoor unit.
An inverter 32 for the compressor 1 and an inverter 33 for the blower 21 of the outdoor unit are connected to the outdoor unit controller 31. Further, as peripheral devices, the drive control unit 34 of the expansion valve 7, the drive control unit 48 of the flow rate adjusting valve 25, the solenoid valve 5 are included.
A, 5B drive control unit 35, temperature sensors 9, 10A, 1
0B temperature converter 36, pressure sensor 8, 11A,
A pressure converter 37 for 11B is connected to the outdoor unit controller 31.

On the other hand, the control device for the indoor unit 50A includes an indoor unit control section 51A and an inverter 38A for the blower 24A of the indoor unit. The inverter 38A is connected to an air volume setting unit 46A that determines the air volume according to the setting status of the VAV unit 45A installed in each air conditioning zone. The indoor unit control unit 51A has peripheral devices including a drive control unit 39A for the expansion valve 15A, a drive control unit 41A for the flow rate adjusting valve 14A, and temperature sensors 17A, 19A, 20A, and 2A.
The temperature converter 42A for 2A and 26A, the pressure converter 43A for the pressure sensor 16A, and the temperature setting unit 44A are connected. The control devices in the indoor units 50B and 50C are similarly configured, and the indoor unit control units 51B and 51C and other reference numbers are denoted by reference numerals B and C, respectively.

The outdoor unit controller 31 and each indoor unit controller 51
A, 51B, and 51C are connected by a communication means, and the outdoor unit control unit 31 is the indoor unit control units 51A, 51B, and 51C.
You can always know the situation of. The outdoor unit control unit 31
The indoor unit load amounts sent from the indoor unit control units 51A, 51B, 51C are integrated for each operation mode, and a control signal corresponding to the larger operation mode load amount is sent to the inverter 32 for the compressor 1. . Inverter 32
Drives the compressor 1 in accordance with this control signal. Further, the outdoor unit control unit 31 sets the heat exchanger 6 of the outdoor unit to the same operation mode as the operation mode of the smaller load amount of all the indoor units, that is, when the load of the cooling operation is smaller. The peripheral devices are controlled so that the heat exchanger 6 of the outdoor unit 30 functions as an evaporator and as a condenser when the load of heating operation is smaller.

The indoor unit control units 51A, 51B and 51C are V
Information on the blown air temperature is obtained from the AV units 45A, 45B, and 45C, and the temperature setting sections 44A and 44 are respectively provided.
B and 44C. Then, the difference between the temperature data of the intake air temperature sensors 26A, 26B, 26C and the temperature data of the temperature setting units 44A, 44B, 44C is calculated,
Each indoor unit determines an operation mode of cooling operation or heating operation. That is, since the temperature of air blown out from the indoor unit is affected by the temperature of air sucked in and the humidity in the indoor unit, the load increase / decrease amount in consideration of these factors is added, and the load amount corresponding to the output of the compressor 1 is changed to the outdoor mode as well as the outdoor unit. It is sent to the machine control unit 31.

Further, the air volume setting units 46A, 46B, 46C
Determines the blown air volume based on the information from the VAV units 45A, 45B, 45C. The blower inverters 38A, 38B, 38C of the indoor unit receive the air volume signals from the respective air volume setting units 46A, 46B, 46C,
The blowers 24A, 24B, and 24C of the indoor units are driven to control the amount of blown air. In addition, solenoid valves 5A and 5B, 13A and 23
A, 13B and 23B, and 13C and 23C are controlled so that one of them is in an open state and the other is in a closed state.

Next, the operation of the above configuration will be described. FIG. 4 shows the flow of the refrigerant during the cooling only operation in which all the indoor units are cooled. When all the indoor units are in the cooling operation, the solenoid valve 5B is open in the outdoor unit,
The solenoid valve 5A is closed, and the solenoid valve 1
3A, 13B, 13C are open, respectively, solenoid valve 23
A, 23B, and 23C are controlled to be in a closed state. The heat exchanger 6 of the outdoor unit is a condenser, and the heat exchanger 18 of each indoor unit.
A, 18B and 18C act as an evaporator.

That is, in the outdoor unit 30, the high pressure gas refrigerant from the compressor 1 is supplied to the solenoid valve 5B as shown by the arrow.
And is liquefied in the heat exchanger 6. Then, after passing through the subcooling heat exchanger 4 and the liquid tank 27, the refrigerant pipe R1 enters the subcooling heat exchanger 12 of the branch unit 40. The refrigerant is heat-exchanged with the gas refrigerant discharged from the heat exchangers 18A, 18B, 18C of the indoor units 50A, 50B, 50C in the supercooling heat exchanger 12, and becomes a liquid refrigerant having an increased degree of supercooling.

Further, the refrigerant is branched by a branch pipe,
Each of the flow rate adjusting valves 14A, 14B, 14C enters in parallel and is subsequently decompressed by the expansion valves 15A, 15B, 15C,
It becomes a low temperature gas-liquid mixed state. Next, the refrigerant is the heat exchanger 1
Heat is exchanged with air in 8A, 18B, and 18C, and becomes a gaseous refrigerant. Then, the solenoid valves 13A, 13B, 13
It returns to the subcooling heat exchanger 12 via C, and cools the liquid refrigerant coming from the outdoor unit 30 through the refrigerant pipe R1. The refrigerant exiting the subcooling heat exchanger 12 returns to the compressor 1 of the outdoor unit 30 via the refrigerant pipe R2. Flow rate adjusting valves 14A, 14
B and 14C constitute the flow rate adjusting means of the indoor unit of the invention, and the supercooling heat exchanger 12 constitutes the first supercooling heat exchanger of the invention.

During this period, the expansion valve 7, the flow rate adjusting valve 25, the blower 21, the indoor units 50A, 50B of the outdoor unit 30,
50C flow control valves 14A, 14B, 14C, expansion valve 1
Control of 5A, 15B, and 15C is performed as follows.
First, the outdoor unit controller 31 holds the expansion valve 7 in a fully opened state. Next, the outdoor unit controller 31 uses the pressure sensor 8
The pressure of the refrigerant is detected by and the saturation temperature of the refrigerant entering the flow rate adjusting valve 25 is calculated. Then, the flow rate adjusting valve 25 is controlled so that the difference with the temperature detected by the temperature sensor 9, that is, the degree of supercooling becomes the degree of supercooling obtained from the calculation of the relational expression between the load of the outdoor unit and the degree of supercooling that is determined in advance. To do. The relationship between the load of the outdoor unit and the supercooling degree level is stored by and read from the graph form showing levels A1 to A10 as shown in FIG.

Further, a signal by, for example, PID control or step control is output to the blower inverter 33 so that the pressure detected by the discharge side pressure sensor 11A of the compressor 1 becomes a preset value, and the blower 21 Is driven to control the air volume.

On the other hand, the indoor unit control units 51A, 51B, 51
At C, the pressure of the refrigerant is detected by the pressure sensors 16A, 16B, 16C, and the saturation temperature of the refrigerant entering each expansion valve 15A, 15B, 15C is calculated. Then, the temperature sensor 17A,
The difference between the temperatures detected by 17B and 17C, that is, the actual degree of supercooling is calculated, and the degree of supercooling obtained from the relational expression between the load of the indoor unit and the degree of supercooling is obtained as in the case of the outdoor unit. Thus, the flow rate adjusting valves 14A, 14B, 14C are controlled. The above-mentioned relational expression can be represented by a graph as shown in FIG. 6, for example, and the degree of supercooling of the levels B1 to B10 is obtained according to the load.

Further, temperature sensors 19A, 19B, 19
The expansion valve 15 is adjusted so that the temperature difference between the refrigerant at the inlets and outlets of the heat exchangers 18A, 18B, and 18C, that is, the degree of superheat is constant, depending on the detected temperatures of C, 20A, 20B, and 20C.
Control A, 15B, 15C. Here, each indoor unit 50
If the loads of A, 50B, and 50C are equal, the openings of the flow rate adjusting valves 14A, 14B, and 14C are the same.
In this case, the refrigerant flows from the branch unit 40 to each indoor unit 50.
A, 50B, 50C are evenly distributed to the indoor units 50A,
The blown air temperatures of 50B and 50C are the same.

Next, for example, when the load of the indoor unit 50A is heavy and the air volume is set large, and the load of the indoor units 50B and 50C is light and the air volume is set small, the indoor unit 5
The blowout temperatures of 0B and 50C begin to drop. Therefore, the indoor unit control units 51B, 5 of the indoor units 50B, 50C.
1C outputs a signal for reducing the load amount to the outdoor unit controller 31. In response to this, the outdoor unit control unit 3
1 decreases the control signal to the inverter 32 for the compressor, and the output of the compressor 1 decreases. At the same time, the flow rate adjusting valve 25 is controlled so as to increase the degree of supercooling because the load becomes smaller. However, since the degree of supercooling of the refrigerant discharged from the heat exchanger 6 increases as the output decreases, the flow rate adjusting valve 25 opens too much. Does not change.

At the same time, since the degree of heating of the refrigerant in the indoor units 50B, 50C is reduced, the indoor unit control sections 51B, 5
1C reduces the opening of the expansion valves 15B and 15C. As a result, the refrigerant flow rate of the entire refrigeration cycle decreases, and the degree of supercooling of the liquid refrigerant sent from the branch unit 40 to each indoor unit side increases. During this time, since the discharge pressure of the compressor 1 is controlled to be constant, each indoor unit 5
0A, 50B, 50C expansion valves 15A, 15B, 15C
The pressure of the entering refrigerant does not change.

Here, the expansion valves 15B and 15C only set the heating degree of the heat exchangers 18B and 18C to a constant level and do not control the temperature of the blown air or the flow rate of the refrigerant, so that the temperature of the blown air is lowered and set. It may happen that the temperature does not recover. As a countermeasure against this, the indoor unit control unit 5 is configured to reduce the degree of supercooling of the refrigerant entering the expansion valves 15B and 15C.
1B and 51C are flow rate adjusting valves 14 according to the above changes.
The opening degrees of B and 14C are controlled so as to be reduced.

That is, when the opening degree of the flow rate adjusting valves 14B and 14C is reduced, the pressure at the inlet of the expansion valves 15B and 15C is reduced, and the flow rate of the refrigerant flowing through the heat exchangers 18B and 18C is reduced. As a result, the amount of heat exchange decreases and the temperature of the blown air rises, and the temperature becomes the same as the temperature of the blown air of the indoor unit 50A with a large load. FIG. 7 is a Mollier diagram of the refrigerating cycle showing the above-mentioned control procedure for the degree of supercooling.

Since the branch unit 40 includes the subcooling heat exchanger 12, the flow rate adjusting valves 14A, 14B,
The degree of supercooling of the liquid refrigerant entering 14C can be increased, and the refrigerant does not start to expand even if the opening degree of the flow rate adjusting valve is narrowed down. Therefore, the control range of the flow rate adjusting valve is expanded.

The subcooling heat exchanger 12 also serves to completely gasify the returned refrigerant. That is, when the blowing air volumes of all the indoor units 50A, 50B, 50C are rapidly reduced, the control speed of the expansion valves 15A, 15B, 15C cannot keep up with the heat exchangers 18A, 18B, 18C.
Even if the liquid refrigerant that could not be completely evaporated in the above flows, the subcooling heat exchanger 12 functions as a temporary heat storage device, so that the liquid compression phenomenon in which the liquid refrigerant enters the compressor 1 can be prevented. Similarly, since the degree of heating of the gas refrigerant entering the compressor 1 can be secured by the subcooling heat exchanger 12, each indoor unit 50A,
The heating degree of the expansion valves 15A, 15B, 15C of 50B, 50C can be set to a small degree, and the heat exchangers 18A, 18B, 18C
Can be used more efficiently.

Next, the flow of the refrigerant during the heating only operation in which all the indoor units are heated will be described with reference to FIG.
When all the indoor units are heated, the solenoid valve 5A is opened and the solenoid valve 5B is closed in the outdoor unit.
In the indoor unit, the solenoid valves 23A, 23B, 23C are controlled to be in the open state and the solenoid valves 13A, 13B, 13C are in the closed state. The heat exchanger 6 of the outdoor unit functions as an evaporator, and the heat exchangers 18A, 18B, 18C of the indoor units function as condensers.

The high-pressure gas refrigerant from the compressor 1 of the outdoor unit 30 enters the branch unit 40 via the refrigerant pipe R3. The refrigerant is branched here, and solenoid valves 23A, 23B, 2
After passing through 3C, it enters the heat exchangers 18A, 18B, 18C of the indoor units 50A, 50B, 50C and is liquefied. After that, it passes through the subcooling heat exchanger 12 of the branch unit, returns to the indoor unit through the refrigerant pipe R1, and enters the subcooling heat exchanger 4 through the liquid tank 27. The refrigerant is heat-exchanged with the gas refrigerant from the heat exchanger 6 in the supercooling heat exchanger 4 to become a liquid refrigerant having an increased degree of supercooling.

Further, the refrigerant is decompressed by the expansion valve 7,
A low-temperature gas-liquid mixed state is established and the heat exchanger 6 is entered. The refrigerant is heat-exchanged with the outdoor air in the heat exchanger 6 to become a gas, and advances to the supercooling heat exchanger 4 via the solenoid valve 5A. Here, while cooling the liquid refrigerant coming from the liquid tank 27 as described above,
It itself becomes a gas refrigerant with increased heating. After that, the refrigerant returns to the compressor 1 via the accumulator 3. Here, the heat exchanger 4 constitutes the second supercooling heat exchanger of the invention.

During this time, the flow rate adjusting valves 14A, 14
B, 14C, the expansion valves 15A, 15B, 15C, the flow rate adjusting valve 25, the blower 21, and the expansion valve 7 are controlled as follows. First, each indoor unit control unit 51A, 51B, 51C
Thus, the expansion valves 15A, 15B, 15C are held fully open. Next, the outdoor unit controller 31 detects the pressure of the refrigerant with the pressure sensor 8 and calculates the saturation temperature of the refrigerant entering the expansion valve 7. Then, the difference from the temperature detected by the pressure sensor 9,
That is, the flow rate adjusting valve 25 is controlled so that the degree of supercooling becomes the degree of supercooling obtained from the relational expression between the load of the outdoor unit and the degree of supercooling.
The above relational expressions are levels C1 to C depending on the load as shown in FIG.
The degree of supercooling indicated by 10 is given. Further, a signal by, for example, PID control or step control is output to the blower inverter 33 so that the pressure detected by the pressure sensor 11B of the compressor 1 becomes a preset value, and the blower 21 is driven to change the air volume. Control.

On the other hand, the indoor unit control units 51A, 51B, 51
At C, the pressure of the refrigerant is detected by the pressure sensors 16A, 16B, 16C, and the saturation temperature of the refrigerant entering each of the flow rate adjusting valves 14A, 14B, 14C is calculated. Then, the temperature sensor 17
The temperature difference detected by A, 17B, and 17C, that is, the degree of subcooling is calculated, and the flow rate adjusting valve 14 is operated so that this is always constant.
Control A, 14B and 14C. In addition, the outdoor unit control unit 3
In No. 1, the expansion valve 7 is controlled based on the temperatures detected by the temperature sensors 10A and 10B so that the heating degree of the heat exchanger 6 is maintained constant, as in the indoor unit during the cooling operation.

Here, each indoor unit 50A, 50B, 50C
If the load is equal, the flow rate adjustment valves 14A, 14B,
The openings of 14C are the same. In this case, the refrigerant is evenly distributed from the branch unit 40 to the indoor units 50A, 50B, 50C, and the indoor air temperatures of the indoor units 50A, 50B, 50C are the same.

Next, for example, when the load of the indoor unit 50A is heavy and the air volume is set large, and the load of the indoor units 50B and 50C is light and the air volume is set small, the indoor unit 50 is
B and 50C blowout air temperatures begin to rise.
Therefore, the indoor unit controller 51B of the indoor units 50B and 50C,
51C outputs a signal for reducing the load amount to the outdoor unit controller 31. In response to this, the outdoor unit control unit 31 lowers the control signal to the compressor inverter 32, and the output of the compressor 1 is reduced accordingly.

At the same time, since the degree of supercooling of the refrigerant in the indoor units 50B and 50C is reduced, the indoor unit control section 51B,
51C reduces the opening of the flow rate adjusting valves 14B and 14C. As a result, the degree of superheat increases, the amount of heat exchange decreases, and the temperature of the blown air decreases to the same temperature as the temperature of the blown air of the indoor unit 50A having a large load. In the indoor unit 50A in which the load does not change, the refrigerant flow rate does not change and the blown air temperature does not change due to the balance between the output change of the compressor 1 and the control of the opening of the flow rate adjusting valve. FIG. 10 is a Mollier diagram of the refrigeration cycle showing the above control procedure.

In this heating operation, since the degree of supercooling is controlled to be kept constant, the degree of supercooling is increased and a large amount of liquid refrigerant is accumulated in the heat exchangers 18A, 18B, 18C, and the entire refrigeration cycle is cooled by the refrigerant. The occurrence of a defect phenomenon that causes a shortage is prevented. Further, the subcooling heat exchanger 4 of the outdoor unit serves to completely liquefy the returned refrigerant. That is, when the blowing air volume of the indoor units 50A, 50B, 50C is rapidly reduced, the flow rate adjusting valves 14A, 14B,
Even if the control speed of 14C cannot catch up and the uncondensed gas refrigerant flows in the outdoor unit 30, the supercooling heat exchanger 4 functions as a temporary heat storage device, and therefore the controllability by the gas refrigerant entering the expansion valve 7 is improved. Can be prevented. Similarly, since the degree of heating of the gas refrigerant entering the compressor 1 can be increased by the supercooling heat exchanger 4, the discharge temperature of the compressor 1 becomes higher and the heating capacity is improved accordingly.

Next, the operation during the cooling / heating simultaneous cooling main operation in which the cooling operation and the heating operation are performed in parallel and the load of the indoor unit is larger in the cooling operation than in the heating operation will be described. FIG. 11 shows the flow of the refrigerant at this time. Here, for example, as an example, the indoor unit 50A is in the heating operation, the indoor unit 50B,
It is assumed that 50C is cooled. First, in the outdoor unit, the solenoid valve 5B is opened and the solenoid valve 5A is closed, and in the indoor unit, the solenoid valves 23A, 13B and 13C are opened and the solenoid valves 13A, 23B and 23C are closed. . The heat exchanger 6 of the outdoor unit and the heat exchanger 18A of the indoor unit act as condensers, and the heat exchangers 18B and 18C of the indoor unit act as evaporators.

In the outdoor unit 30, the high pressure gas refrigerant from the compressor 1 enters the heat exchanger 6 through the solenoid valve 5B and is liquefied there. The refrigerant discharged from the heat exchanger 6 passes through the supercooling heat exchanger 4 and the liquid tank 27 and enters the supercooling heat exchanger 12 of the branch unit 40 through the refrigerant pipe R1. The high pressure gas refrigerant from the compressor 1 also enters the branching unit 40 via the refrigerant pipe R3. The refrigerant through the refrigerant pipe R3 is the solenoid valve 23.
After passing through A, the heat enters the heat exchanger 18A of the indoor unit 50A and is liquefied there.

The refrigerant having entered the subcooling heat exchanger 12 of the branching unit via the refrigerant pipe R1 is heat-exchanged with the gas refrigerant coming out of the heat exchangers 18B, 18C of the indoor units 50B, 50C to increase the degree of supercooling. Becomes the liquid refrigerant. This refrigerant once merges with the liquid refrigerant coming from the heat exchanger 18A of the indoor unit 50A through the branch pipe, and then enters the indoor units 50B and 50C in parallel. Here, the flow rate adjusting valves 14B and 14C, respectively, and the expansion valves 15B and 15C, respectively, are used to reduce the pressure so that a low-temperature gas-liquid mixed state is established and the heat exchangers 18B and 18C are entered.

The refrigerant is heat-exchanged with air in the heat exchangers 18B and 18C to become a gaseous refrigerant. Then, it returns to the supercooling heat exchanger 12 through the solenoid valves 13B and 13C, and cools the liquid refrigerant that enters from the outdoor unit 30 via the refrigerant pipe R1. The refrigerant exiting the supercooling heat exchanger 12 is the refrigerant pipe R2.
And returns to the compressor 1 of the outdoor unit 30.

During this time, the expansion valve 7 of the outdoor unit 30, the flow rate adjusting valve 25, the blower 21, the flow rate adjusting valve 14A of the indoor unit 50A, the expansion valve 15A, the flow rate adjusting valves 14B and 14C of the indoor units 50B and 50C, and the expansion valve 15B. , 15C is controlled as follows. First, the expansion valve 7 of the outdoor unit controller 31 is held in the fully open state. The flow rate adjusting valve 25 is controlled so that the degree of supercooling calculated by the pressure sensor 8 and the temperature sensor 9 becomes the degree of supercooling calculated in FIG. 5, similarly to the control during the cooling operation.

As for the blower 21, the inverter 3 is controlled so that the pressure detected by the discharge side pressure sensor 11A becomes a preset value, as in the control during the cooling only operation.
3 is driven to control the air volume. On the other hand, in the indoor unit controller 51A of the indoor unit 50A, the expansion valve 15A is held fully open. Then, the flow rate adjusting valve 14A is controlled so that the degree of subcooling becomes constant, similarly to the control of the flow rate adjusting valve of the indoor unit during the heating only operation.

Further, in the indoor unit control sections 51B and 51C of the indoor units 50B and 50C, the expansion valves 15B and 15C are controlled so that the degree of superheat becomes constant as in the control of the expansion valve of the indoor unit during the cooling only operation. The flow rate control valves 14B and 14C are controlled so that the degree of subcooling is also the degree of subcooling obtained from the graph of the degree of subcooling and the load of the indoor unit in FIG. When the load on each indoor unit changes, the description is omitted because it is the same as the indoor unit in the same operation mode in the cooling only operation or the heating only operation. FIG.
2 is a Mollier diagram of the refrigeration cycle showing the above control procedure.

Next, the operation during the cooling / heating simultaneous operation main operation in which the indoor unit load is larger in the heating operation than in the cooling operation in the cooling / heating simultaneous operation will be described with reference to FIG. Here, for example, as an example, the indoor unit 50A
Is for cooling operation, and the indoor units 50B, 50C are for heating operation. First, in the outdoor unit, the solenoid valve 5A is opened and the solenoid valve 5B is closed, and in the indoor unit, the solenoid valves 13A and 23B are closed.
B and 23C are controlled to be in an open state, and the solenoid valves 23A, 13B and 13C are controlled to be in a closed state. The heat exchanger 6 of the outdoor unit and the heat exchanger 18A of the indoor unit are the evaporator and the heat exchanger 18 of the indoor unit.
B and 18C act as a condenser.

In this operation, the high-pressure gas refrigerant from the compressor 1 of the outdoor unit 30 enters the branch unit 40 via the refrigerant pipe R3. Here, the refrigerant passes through the solenoid valves 23B and 23C, and then the heat exchangers 18B and 18C of the indoor units 50B and 50C.
Enters and is liquefied. The refrigerant discharged from the heat exchangers 18B and 18C joins in the branch pipe of the branch unit 40, part of which is directed to the indoor unit 50A, and the rest is the supercooling heat exchanger 12 and the refrigerant pipe R.
After entering 1, the liquid enters the liquid tank 27 of the outdoor unit, and then enters the subcooling heat exchanger 4.

In the outdoor unit, the refrigerant is the subcooling heat exchanger 4
At this time, heat exchange is performed with the gas refrigerant from the heat exchanger 6, and the liquid refrigerant is increased in supercooling. Then, the refrigerant is decompressed by the expansion valve 7 into a low-temperature gas-liquid mixed state, and enters the heat exchanger 6. The refrigerant that has been heat-exchanged with air in the heat exchanger 6 and has become a gas passes through the subcooling heat exchanger 4 via the solenoid valve 5A and cools the liquid refrigerant that has come from the liquid tank 27 as described above. It itself becomes a gas refrigerant with an increased degree of superheat.

On the other hand, the refrigerant that has entered the indoor unit 50A is decompressed by the expansion valve 15A and enters a low-temperature gas-liquid mixed state. Next, heat is exchanged with the air in the heat exchanger 18A to become a gaseous refrigerant. After that, it goes to the outdoor unit 30 through the refrigerant pipe R2 through the solenoid valve 13A. The refrigerant merges with the refrigerant that has left the subcooling heat exchanger 4 in the outdoor unit 30, and returns to the compressor 1 via the accumulator 3.

During this period, the expansion valve 7 of the outdoor unit 30, the flow rate adjusting valve 25, the blower 21, the flow rate adjusting valve 14A of the indoor unit 50A, the expansion valve 15A, the flow rate adjusting valves 14B and 14C of the indoor units 50B and 50C, and the expansion valve 15B. , 15C is controlled as follows. First, the outdoor unit control unit 31 controls the expansion valve 7 so that the degree of superheat is constant, as in the control during the heating only operation. Similarly, the flow rate adjusting valve 25 is controlled to a value obtained from the relationship between the supercooling degree level and the outdoor unit load shown in FIG. 9. As for the blower 21, the blower inverter 33 is driven so that the pressure detected by the pressure sensor 11B becomes a preset value, and the air volume control is performed, as in the control during the heating only operation.

The control of the indoor unit control section 51A of the indoor unit 50A is the same as the control of the indoor units 50B and 50C during the main heating / cooling simultaneous cooling main operation, and therefore will be omitted. In addition, the indoor units 50B, 5
The control of the indoor unit control units 51B and 51C of 0C is also similar to that of the indoor unit 50A during the simultaneous main heating / cooling main operation.

Next, for example, when the indoor unit 50A is in heating operation and the indoor units 50B and 50C are in cooling operation, and the total cooling load and the heating load are the same, the heat exchanger 6 of the outdoor unit is set to the difference between both loads. Since it is not necessary to act as a condenser or an evaporator, the flow rate adjusting valve 25 is closed and the blower 21 is also stopped. Then, all the refrigerant that has flowed through the indoor unit 50A flows into the indoor units 50B and 50C that are parallel to each other, and the amount of heat is balanced.

The control flow in the outdoor unit control unit and the indoor unit control unit described above is briefly shown in FIGS. That is, in the outdoor unit controller, as shown in FIGS. 14 and 15, first, in step 101, the indoor unit loads from the indoor unit controllers 51A to 51C are input, and in step 102, these are integrated for each operation mode. . Then, in step 103, the cumulative load amounts for each mode are compared, and when the cooling load is large, the process proceeds to step 104, when the heating load is large, the process proceeds to step 113, and when both loads are the same, the process proceeds to step 124.

When the cooling load is large, first step 1
At 04, a control signal corresponding to the load amount of the cooling load is sent to the inverter 32 to drive the compressor 1, and at step 105, the heat exchanger 6 is set to a mode of working as a condenser. In the next step 106, the heat exchanger load amount is obtained as the difference between the cooling load and the heating load,
In step 107, the target control supercooling degree is obtained by calculation or graph reading.

At step 108, the actual degree of supercooling is obtained from the difference between the saturation temperature of the refrigerant based on the value detected by the pressure sensor 8 and the temperature detected by the temperature sensor 9. Then, in step 109, the flow rate adjusting valve 25 is controlled so that the controlled supercooling degree and the actual supercooling degree match. After that, in step 110, the discharge pressure of the compressor 1 is detected by the pressure sensor 11A, and in step 111, the inverter 33 is driven so that the discharge pressure becomes a preset value, and the air volume of the blower 21 is controlled. Then, the process returns to step 101.

Next, when the heating load is large, in step 113, the control signal corresponding to the heating load is sent to the inverter 32 to drive the compressor 1, and in step 114, the heat exchanger is operated. The mode in which 6 operates as an evaporator is set. In the next step 115, the heat exchanger load amount is obtained as the difference between the heating load and the cooling load, and in step 116, the target control subcooling degree is obtained by calculation or graph reading.

In step 117, the actual degree of supercooling is obtained from the difference between the saturation temperature of the refrigerant based on the value detected by the pressure sensor 8 and the temperature detected by the temperature sensor 9. Then, in step 118, the flow rate adjusting valve 25 is controlled so that the controlled supercooling degree and the actual supercooling degree match. Subsequently, in step 119, the degree of superheat of the heat exchanger 6 is obtained from the temperatures detected by the temperature sensors 10A and 10B, and step 120
The expansion valve 7 is controlled so as to keep this constant. After this, in step 121, the suction pressure of the compressor 1 is detected by the pressure sensor 11B, and step 12
In 2, the air flow rate of the blower 21 is controlled so that this pressure becomes a preset value. Then, the process returns to step 101.

When the cooling load and the heating load are the same, the flow rate adjusting valve 25 is closed in step 124, and the blower 21 is stopped in step 125.

On the other hand, in each indoor unit control section, as shown in FIG.
As shown in FIG. 17, in step 201, the VAV unit 45 inputs information on the required blow-out air temperature to the temperature setting unit 44 and holds it. Then step 2
In 02, the temperature sensor 26 detects the intake air temperature of the heat exchanger 18. Then, in step 203, the required blowout air temperature (set temperature) is compared with the intake air temperature to determine the operation mode of the cooling operation or the heating operation.

In the case of the cooling operation mode, step 20
4, first, the actual temperature of the air blown from the heat exchanger 18 is detected by the temperature sensor 22, and in step 205,
The temperature difference between the actual blown air temperature and the set temperature is calculated. Then, in step 206, a load amount is obtained by adding a correction amount in consideration of the intake air temperature, humidity and the like based on the temperature difference. In step 207, this load amount is transmitted to the outdoor unit by the communication means.

In the next step 208, the target degree of control supercooling is obtained by calculation or graph reading based on the load amount. Then, in step 209, the actual degree of supercooling is obtained from the difference between the saturation temperature of the refrigerant based on the detection value of the pressure sensor 16 and the temperature detected by the temperature sensor 17, and in step 210, the control degree of supercooling and the actual degree of supercooling are obtained. The flow rate adjusting valve 14 is controlled so as to match the degrees. Then, in step 211, the temperature sensors 19 and 2
The degree of superheat is obtained from each detected temperature of 0, and step 212
The expansion valve 15 is controlled so that the degree of superheat becomes constant.

On the other hand, in the heating operation mode, the actual blown air temperature of the heat exchanger 18 is detected in step 214, and the temperature difference between the set temperature and the actual blown air temperature is calculated in step 215. Then, in steps 216 and 217, the corrected load amount is sent to the outdoor unit, as in steps 206 and 207 during cooling. Then, in step 218, the actual degree of supercooling is obtained from the saturation temperature based on the pressure detected by the pressure sensor 16 and the temperature of the temperature sensor 17, and in step 219, the flow rate adjusting valve 14 is adjusted so that the degree of supercooling is always constant. Is controlled.

In this embodiment, the heat pump type air conditioner constructed as described above is connected in parallel from a single outdoor unit to a plurality of indoor units via a branching unit. To the air conditioning zone, the air volume can be varied by the VAV unit for each air conditioning zone, the branch unit is equipped with a supercooling heat exchanger, and a solenoid valve that can be selected between cooling operation and heating operation by switching between them, and the outdoor unit is undercooled. The heat exchanger was equipped with a flow rate adjusting valve and an expansion valve on the liquid pipe side, and a flow rate adjusting valve and an expansion valve on the liquid pipe side of the indoor unit. Then, in the indoor unit, during the cooling operation, the flow rate control valve is controlled so as to have a supercooling degree according to the load of each indoor unit, and the expansion valve is controlled so that the superheat degree becomes constant, while during the heating operation, The flow control valve was controlled so that the degree of supercooling was constant. On the other hand, in the outdoor unit, the flow rate control valve is controlled so that the degree of supercooling corresponds to the load on the outdoor unit, and when the heat exchanger of the outdoor unit is in the condenser mode, the expansion valve of the outdoor unit is fully opened. In the evaporator mode, the superheat degree is controlled to be constant. As a result, the cooling operation and the heating operation can be arbitrarily performed according to the individual requirements of each air conditioning zone, and the blowing temperature of the indoor unit does not change even if the air volume is changed, and stable air conditioning can be obtained. Have. Further, there is an effect that the room temperature of each air conditioning zone can be arbitrarily controlled by the change in the air volume without being affected by the load state of other indoor units.

Therefore, it is not necessary to install a large number of indoor units in a large number of individual air-conditioning zones, and it is not necessary to install a large number of indoor units, thus improving maintainability. Further, during the cooling operation, especially the subcooling heat exchanger 12
As a result, the degree of supercooling of the refrigerant entering the flow rate adjusting valve is increased, so that the adjustment range of the flow rate adjusting valve can be expanded and a stable refrigeration cycle can be obtained. Furthermore, when the amount of air blown from the indoor unit suddenly decreases, the subcooling heat exchanger 12 acts as a temporary heat storage device during cooling, preventing the liquid compression phenomenon in which the liquid refrigerant enters the compressor 1, and reducing the subcooling heat during heating operation. The exchanger 4 functions as a temporary heat storage device, promotes reliable liquefaction of the refrigerant, and prevents the controllability of the expansion valve 7 from decreasing.

Depending on the load condition of the air conditioning zone, it may be desired to raise the temperature of the air blown out from a particular indoor unit during the cooling operation or decrease it during the heating operation. Even in these cases, the flow control valve is controlled by correcting the degree of supercooling required for each operation so as to reduce the degree of supercooling during cooling operation and increase it during heating operation. As a result, the control range of the VAV unit can be returned to the normal state. In addition, each indoor unit 50
A, 50B, 50C are installed in various places, and the outdoor unit 3
Even if there is a difference in the pipe length from 0, the refrigerant state between the expansion valve and the flow rate adjustment valve of each indoor unit can be made the same, so the same air conditioning capacity can be obtained without considering the pipe pressure loss during installation work. To be

FIG. 18 shows a second embodiment of the present invention.
In this embodiment, in contrast to the system configuration of the first embodiment described above, two indoor units are dedicated to cooling operation and heating operation, respectively, and VAV is provided to each air conditioning zone by a dual duct system.
It is something that blows out through. That is, the indoor unit 50
B'and 50C 'are indoor units dedicated to cooling operation and heating operation, respectively. A VAV unit 45B' dedicated to cooling is connected to a duct 47B 'dedicated to cooling, and a VAV dedicated to heating is connected to a duct 47C' dedicated to heating. The unit 45C 'is connected. Also, VAV units 45B 'and 45C'
Are installed in pairs, and VAV unit 4
The air blown out from 5B 'and 45C' is mixed and blown out to each air conditioning zone ZB1 ', ZB2', ZB3 '. The other structure is the same as that of the first embodiment. The flow of the refrigerant in each operation mode is the same as that in the previous embodiment, and thus the description of the operation will be omitted.

According to this embodiment, the same effects as those of the first embodiment are obtained, and the air conditioning zones ZB1 'and ZB are provided.
The cooling operation and the heating operation can be selected for each 2'and ZB3 '. Moreover, since heat is transferred in the air conditioner, there is an advantage that a large amount of energy can be saved without discarding the waste heat of the two heat sources unlike the conventional dual duct system.

FIG. 19 shows a third embodiment of the present invention.
In this embodiment, in addition to the refrigerant circuit of the first embodiment described above, the branch unit is abolished and the subcooling heat exchanger that was in the branch unit is provided for each indoor unit. That is, the refrigerant pipe R1 ′ extending from the outdoor unit 30,
R2 'and R3' are branched and each indoor unit 50A ', 50
B ', 50C' are connected in parallel. Then, in each indoor unit, the refrigerant pipe R1 ′ is connected to the supercooling heat exchanger 12
After passing through A, 12B, 12C, the flow rate adjusting valve 14A,
14B and 14C are connected. Further, the refrigerant pipe R2 'enters the other passage of the subcooling heat exchangers 12A, 12B, 12C and is connected to the gas pipe side of the heat exchangers 18A, 18B, 18C via the solenoid valves 13A', 13B ', 13C'. It is connected. Further, the refrigerant pipe R3 ′ is connected to the solenoid valves 23A ′, 23
Heat exchangers 18A, 18B, 18 via B ', 23C'
It is connected to the C gas pipe.

The solenoid valves 13A ', 23A' and 1
Similar to the first embodiment, 3B 'and 23B' and 13C 'and 23C' are controlled so that when one is open, the other is closed. The other structure is the same as that of the first embodiment. The flow of the refrigerant in each operation mode is also the same as that in the first embodiment, so the description of the operation will be omitted.

According to this embodiment, the same effect as that of the first embodiment is obtained, and since the subcooling heat exchanger is provided separately for each indoor unit, all the refrigerant flowing to the expansion valve is either. There is an advantage that the degree of supercooling can be increased by passing through the subcooling heat exchanger, and the supercooling heat exchanger can be easily handled, small in size, and inexpensive.

In each of the above embodiments, three indoor units are connected, but the number of indoor units is not limited to this, and two or four or more indoor units can be similarly used. Therefore, if there is an indoor unit that does not blow air, it is possible to fully close the flow rate adjusting valve and not operate it. Further, a plurality of branch units may be provided and a plurality of indoor units may be connected to each branch unit, and further, the first embodiment and the third embodiment may be combined.

[0084]

As described above, according to the present invention, in an air conditioner in which a plurality of indoor units are connected in parallel to one outdoor unit, the gas pipes of the heat exchangers of each indoor unit and the outdoor unit are high pressure gas pipes. Or by selectively connecting to the low-pressure gas pipe, it becomes possible to select cooling operation and heating operation for each indoor unit,
Ventilation of each indoor unit is guided to multiple air conditioning zones by ducts, and each air conditioning zone is equipped with a VAV unit,
Since the room temperature of each air conditioning zone is controlled by changing the air flow rate by the V unit, the room temperature adjustment for each of a number of air conditioning zones is performed by the VAV unit having a simple structure, and the requirements of all the air conditioning zones can be met. It has the effect of controlling to a comfortable room temperature. Further, since it is not necessary to individually install a large number of indoor units, the maintainability is improved, and since thermal energy is transferred between the indoor units during the simultaneous cooling / heating operation, a great energy saving effect can be obtained.

Further, in the cooling operation, the degree of supercooling of the refrigerant becomes a value determined according to the load of the indoor unit,
Further, by controlling the flow rate adjusting means so that the degree of subcooling becomes constant during the heating operation, even if the blowing air amount is changed, the expansion valve is not increased in each indoor unit without causing interference with other indoor units. The pressure of the entering refrigerant can be maintained constant, and stable air conditioning of the blown air temperature is performed.
In addition, this allows the expansion valve of the indoor unit to be in the same state, so there is no difference in capacity depending on the installation location of each indoor unit,
There is no need to correct the capacity when designing an air conditioner, and the installation work can be simplified. And, there is an effect that the temperature of the blown air can be arbitrarily controlled as required.

By providing the first subcooling heat exchanger between the liquid pipes and the low pressure gas pipes which head toward the plurality of indoor units,
The control range of the flow rate by the flow rate adjusting means is expanded. As a result, even if the amount of air blown out from the indoor unit is sharply reduced, the returning refrigerant is reliably gasified by the heat storage action of the subcooling heat exchanger, and damage to the compressor is prevented. In addition, by providing the second supercooling heat exchanger between the liquid pipe and the low-pressure gas pipe toward the heat exchanger of the outdoor unit, it is possible to increase the degree of superheat of the gas refrigerant entering the compressor of the outdoor unit, The heating capacity is improved, and even when the amount of air blown from the indoor unit is sharply reduced, it is possible to promote the reliable liquefaction of the return refrigerant by the heat storage function of the subcooling heat exchanger.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a refrigerant circuit diagram in the embodiment.

FIG. 3 is a diagram showing a control device in an indoor unit and an outdoor unit.

FIG. 4 is a diagram showing a flow of a refrigerant during a cooling only operation.

FIG. 5 is a graph showing the relationship between the load of the outdoor unit and the degree of supercooling during the cooling only operation.

FIG. 6 is a graph showing the relationship between the load on the indoor unit and the degree of supercooling.

FIG. 7 is a Mollier diagram of a refrigeration cycle showing a control procedure during a cooling only operation.

FIG. 8 is a diagram showing a refrigerant flow during a heating only operation.

FIG. 9 is a graph showing the relationship between the load on the outdoor unit and the degree of supercooling during the heating only operation.

FIG. 10 is a Mollier diagram of the refrigeration cycle showing the control procedure during the heating only operation.

FIG. 11 is a diagram showing a flow of a refrigerant at the time of main cooling / heating simultaneous cooling main operation.

FIG. 12 is a Mollier diagram of a refrigerating cycle showing a control procedure during simultaneous cooling / heating main operation.

FIG. 13 is a diagram showing a flow of a refrigerant during a main heating / cooling simultaneous heating operation.

FIG. 14 is a flowchart showing a control flow in an outdoor unit control section.

FIG. 15 is a flowchart showing a control flow in an outdoor unit control section.

FIG. 16 is a flowchart showing a control flow in an indoor unit control section.

FIG. 17 is a flowchart showing a control flow in an indoor unit control section.

FIG. 18 is a system configuration diagram showing a second embodiment.

FIG. 19 is a refrigerant circuit diagram showing a third embodiment.

[Explanation of symbols]

1 Compressor 3 Accumulator 4 Supercooling Heat Exchanger 5A, 5B, 5C Electromagnetic Valve 6 Heat Exchanger 7 Expansion Valve 8 Pressure Sensor 9 Temperature Sensor 10A, 10B Temperature Sensor 11A, 11B Pressure Sensor 12 Supercooling Heat Exchanger 13A, 13B, 13C, 23A, 23B, 23C
Solenoid valves 13A ', 13B', 13C ', 23A', 23B ',
23C 'Solenoid valve 14A, 14B, 14C Flow rate adjusting valve 15A, 15B, 15C Expansion valve 16A, 16B, 16C Pressure sensor 17A, 17B, 17C Temperature sensor 18A, 18B, 18C Heat exchanger 19A, 19B, 19C, 20A, 20B , 20C
Temperature sensor 21 Blower 22A, 22B, 22C, 26A, 26B, 26C
Temperature sensor 24A, 24B, 24C Blower 25 Flow control valve 27 Liquid tank 30 Outdoor unit 31 Outdoor unit control unit 32, 33 Inverter 34, 35, 48 Drive control unit 36 Temperature converter 37 Pressure converter 38A, 38B, 38C Inverter 39A , 39B, 39C, 41A, 41B, 41C
Drive control unit 40 Branch unit 42A, 42B, 42C Temperature converter 43A, 43B, 43C Pressure converter 44A, 44B, 44C Temperature setting unit 45A, 45B, 45C, 45B ', 45C' VA
V unit 46A, 46B, 46C Air volume setting unit 47A, 47B, 47C, 47B ', 47C' Duct 50A, 50B, 50C, 50B ', 50C' Indoor unit 50A ", 50B", 50C "Indoor unit 51A, 51B, 51C Indoor unit control unit R1, R2, R3, R1 ', R2', R3 'Refrigerant piping ZA1, ZA2, ZB1, ZB2, ZC, Air conditioning zone ZB1', ZB2 ', ZB3' Air conditioning zone

Claims (5)

[Claims] 1. A unit comprising a heat exchanger, an expansion valve attached to the heat exchanger, a flow rate adjusting means provided in front of the expansion valve, and a first control means for controlling the flow rate adjusting means. Outdoor unit, a heat exchanger, an expansion valve attached to the heat exchanger, flow rate adjusting means provided in front of the expansion valve,
And a plurality of indoor units that are provided with a second control unit that controls the flow rate adjusting unit, and that are connected in parallel to the outdoor unit by refrigerant pipes that form a liquid pipe, a high-pressure gas pipe, and a low-pressure gas pipe of a refrigeration cycle. The air blown from each indoor unit is guided to a plurality of air conditioning zones by ducts, and the VAV unit provided in the duct for each air conditioning zone and the gas pipe connected to the heat exchanger of the outdoor unit are connected to the outdoor unit. First switching means that can be selectively connected to a high-pressure gas pipe or a low-pressure gas pipe toward the heat exchanger, and a gas pipe connected to the heat exchanger of each indoor unit is selected as the high-pressure gas pipe or the low-pressure gas pipe. And a second switching means connectable to each other, selectively controlling each indoor unit individually for cooling operation or heating operation, and controlling the room temperature of each air conditioning zone by changing the air volume by the VAV unit. An air conditioning apparatus characterized in that it is configured so that. 2. The second control means of the indoor unit controls the subcooling degree of the refrigerant contained in the expansion valve of the indoor unit to be a value determined according to the load of the indoor unit during the cooling operation. Controlling the flow rate adjusting means of the indoor unit, and controlling the flow rate adjusting means of the indoor unit so that the degree of supercooling of the refrigerant exiting the heat exchanger of the indoor unit becomes constant during heating operation. The air conditioner according to claim 1. 3. The first control means of the outdoor unit is such that when the heat exchanger of the outdoor unit acts as a condenser, the degree of supercooling of the refrigerant leaving the heat exchanger of the outdoor unit is The flow rate adjusting means of the outdoor unit is controlled so that it becomes a value determined according to the load, and when the heat exchanger of the outdoor unit acts as an evaporator, the degree of supercooling of the refrigerant in the expansion valve of the outdoor unit is The air conditioner according to claim 1 or 2, wherein the flow rate adjusting means of the outdoor unit is controlled so that the value is determined according to the load of the heat exchanger of the machine. 4. In at least one of the indoor units, when the heat exchanger acts as an evaporator, heat is exchanged between the liquid pipe toward the indoor unit and the low pressure gas pipe toward the outdoor unit. The air conditioner according to claim 1, 2 or 3, further comprising a first subcooling heat exchanger for performing the operation. 5. A second filter for performing heat exchange between the liquid pipe and the low pressure gas pipe, which face the heat exchanger of the outdoor unit when the heat exchanger of the outdoor unit acts as an evaporator. A cooling heat exchanger is provided, 3.
The air conditioner according to 3 or 4.