JPH0526530A - Air-conditioner - Google Patents

Abstract

PURPOSE:To ensure constantly proper heating capacity by a method wherein control is effected such that even when there is a high difference in a heating demand between indoor units, the degree of superheat of a refrigerant of a heat-exchanger on the heat source side is kept at a given value. CONSTITUTION:When, during heating operation, a difference in demand capacity is higher than a set value, a two-way valve, corresponding to one, having higher demand capacity, of indoor units whichever it may be, of two-way valves 13 and 23 is opened and the two-way valve corresponding to the indoor unit having lower demand capacity is closed. The opening of a flow rate regulating valve 7 is controlled so that the temperature of a refrigerant flowing in indoor heat- exchangers B1 and B2 forms a given relation based on demand capacity of each indoor unit. Further, the opening of each electronic expansion valve is controlled as the total opening of electronic expansion valves 11 and 12 is kept at a constant value so that the degrees of subcooling of indoor heat- exchangers 12 and 22 are adjusted to values equal to each other.

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 including an outdoor unit and a plurality of indoor units.

[0002]

2. Description of the Related Art Generally, in a multi-type air conditioner consisting of an outdoor unit and a plurality of indoor units, the capacity of the compressor is controlled according to the total required capacity of each indoor unit.

Further, a flow rate adjusting valve and an expansion valve are provided in the liquid pipes connected to the respective indoor units, and the opening of each flow rate adjusting valve is individually controlled according to the required capacity of the corresponding indoor unit. Further, during the cooling operation, the degree of refrigerant superheat in each indoor unit is controlled to be constant by adjusting the opening degree of each expansion valve based on its own temperature sensing.

[0004]

By the way, in the above air conditioner, since the opening degree control of each flow rate adjusting valve is separated for each indoor unit, during heating operation, the required capacity of each indoor unit is large. If there is a difference, the following problems will occur.

That is, in the heating operation, since the flow rate control by the flow rate control valve is performed on the downstream side of each indoor unit, when there is a large difference in the required capacity between the indoor units, the indoor unit with the smaller required capacity is provided. A large amount of liquid refrigerant accumulates in the refrigerant, and the refrigerant circulation amount in the entire refrigeration cycle becomes insufficient.

When the refrigerant circulation amount is insufficient, it is not possible to control the refrigerant superheat degree in the refrigerant heater as the heat source side outdoor heat exchanger to be constant only by controlling the opening degree of each electronic expansion valve.

In order to prevent this, the heating capacity of the refrigerant heater is reduced to lower the heating capacity, or the minimum limit opening of the flow rate adjusting valve is increased to increase the heating capacity ratio of each indoor unit. Although it can be eliminated, in either case, there is a problem that the specifications of the air conditioner are deteriorated.

The present invention has been made in view of the above points, and an object thereof is to maintain a constant degree of subcooling of each indoor unit during a heating operation, even if there is a large difference in the heating demand in the indoor unit. An object of the present invention is to provide an air conditioner that can always ensure an appropriate heating capacity by controlling the degree of refrigerant superheat in a heat source side outdoor heat exchanger to maintain a predetermined value.

[0009]

An air conditioner according to claim 1 is provided with a compressor, a four-way valve, a plurality of indoor heat exchangers connected in parallel, and a liquid pipe communicating with each indoor heat exchanger. Each indoor heat exchanger connected to the provided electronic expansion valve and the heat source side outdoor heat exchanger and connected to each indoor heat exchanger and provided in a gas pipe between each indoor heat exchanger and the four-way valve In an air conditioner comprising a refrigeration cycle equipped with a flow rate adjusting device for adjusting the refrigerant partial flow rate to the compressor, the refrigerant discharged from the compressor is a four-way valve, each indoor heat exchanger, each electronic expansion valve, outdoor heat Means for performing a flow heating operation through a exchanger, and means for controlling the capacity of the compressor and the like in accordance with the total required capacity of each indoor unit during the heating operation,
A means for detecting the refrigerant superheat degree in the outdoor heat exchanger, a means for controlling the total opening degree of the electronic expansion valves so that the detected refrigerant superheat degree has a predetermined value, and in each indoor heat exchanger Controlling the opening and closing of each electronic expansion valve while keeping the total opening of each electronic expansion valve constant so that the degree of subcooling and the degree of subcooling in each indoor heat exchanger are equal And means for doing so.

An air conditioner according to a second aspect is a compressor, a four-way valve, a plurality of indoor heat exchangers connected in parallel, an electronic expansion valve provided in each liquid pipe communicating with each indoor heat exchanger, and While connecting the heat source side outdoor heat exchanger, communicating with each indoor heat exchanger, the refrigerant partial flow rate to each indoor heat exchanger provided in the gas pipe between each indoor heat exchanger and the four-way valve In an air conditioner composed of a refrigeration cycle equipped with a flow rate adjusting device for adjusting, a refrigerant discharged from the compressor is made to flow through a four-way valve, each indoor heat exchanger, each electronic expansion valve, and an outdoor heat exchanger. Means for executing a heating operation, means for controlling the capacity of the compressor and the like according to the total required capacity of each indoor unit during this heating operation, and means for detecting the degree of refrigerant superheat in the outdoor heat exchanger And the detected refrigerant superheat becomes a predetermined value. Means for controlling the total opening degree of each electronic expansion valve, means for detecting the degree of subcooling in each indoor heat exchanger, and each means for making the degree of subcooling in each indoor heat exchanger equal. Means for controlling the opening and closing of the opening of each electronic expansion valve while keeping the total opening of the electronic expansion valve constant,
When the difference between the required capacities of the indoor heat exchangers is larger than a set value, a means for controlling the flow rate adjusting device to increase the flow rate of the one with the larger required capacity, and the opening of the electronic expansion valve on the large side. When the difference between the subcooling degrees of the indoor heat exchangers is equal to or more than the set value and the state is equal to or more than the set value for a certain period of time or more, the control device opens the opening of the flow rate adjusting device by a certain amount. To do.

[0011]

According to the first aspect of the present invention, during heating operation, the capacity of the compressor is controlled in accordance with the total required capacity of each indoor unit. Then, the total opening degree of each electronic expansion valve is controlled so that the refrigerant superheat degree in the heat source side outdoor heat exchanger becomes a predetermined value.
Further, the opening degree of each electronic expansion valve is controlled to be opened and closed while keeping the total opening degree of each electronic expansion valve constant so that the degree of subcooling in each indoor heat exchanger becomes equal.

According to the second aspect of the present invention, when the difference in required capacity between the indoor heat exchangers is larger than the set value, control is performed by the flow rate adjusting device to increase the flow rate having the larger required capacity. Then, by performing the control according to claim 1, the opening degree of each electronic expansion valve is adjusted to be opened and closed while keeping the total opening degree of each electronic expansion valve constant so that the degree of subcooling in each indoor heat exchanger becomes equal. Even if it is controlled, if the opening degree of the electronic expansion valve on the large side is more than the set value and the difference in the degree of subcooling of each indoor heat exchanger is more than the set value for more than a certain time, the flow rate adjustment The opening of the device is controlled to be opened by a certain amount.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, A is an outdoor unit and B is
1 and B2 are indoor units, which constitute the next refrigeration cycle between these units.

An outdoor heat exchanger 3 is connected to a discharge port of a compressor 1 through a four-way valve 2, and a forward check valve 4 and a pair of liquid pipes W1 and W2 are connected to the outdoor heat exchanger 3. The indoor heat exchangers 12 and 22 are connected.

Gas pipes G1 and G are provided in the indoor heat exchangers 12 and 22, respectively.
2, the accumulator 6 is connected through the four-way valve 2 and the check valve 5 in the forward direction, and the suction port of the compressor 1 is connected to the accumulator 6. Electronic expansion valves 11 and 21 are provided on the liquid pipes W1 and W2, respectively. Liquid pipe W1, W2
Refrigerant temperature sensors 17 and 27 are provided respectively. An electronic flow rate adjusting valve 7 is provided between the gas pipes G1 and G2.
To communicate with each other.

In the gas pipes G1 and G2, the flow rate adjusting valve 7
The two-way valve 1 is located at a position closer to the four-way valve 2 than the communication position of
3 and 23 are provided. Flow rate adjusting valve 7 and two-way valves 13, 23
Constitutes a flow rate adjusting device.

The refrigerant heater 30 is connected via the two-way valve 8 from the communicating portion between the check valve 4 and the electronic expansion valves 11 and 21 connected to the outdoor heat exchanger 9 to the accumulator 6 on the suction side of the compressor 1. To communicate with each other.

The refrigerant heater 30 includes a gas burner 31,
The gas burner 3 is equipped with a combustion fan 32, a proportional valve 33, an igniter 34, a flame detector 35, etc. described later.
The refrigerant is heated by the combustion flame No. 1. The outdoor fan 9 is provided near the outdoor heat exchanger 3, and the indoor fans 14 and 24 are provided near the indoor heat exchangers 12 and 22, respectively. Heat exchanger temperature sensors 15 and 25 are attached to the indoor heat exchangers 12 and 22, respectively. Refrigerant temperature sensors 16 and 26 are attached to the gas pipes G1 and G2, respectively.

In the communication portion between the check valve 4 and the electronic expansion valves 11 and 21, the refrigerant temperature sensor 4 is located at a position slightly closer to the electronic expansion valves 11 and 21 than the connecting portion of the system of the refrigerant heater 30.
Attach 1. A refrigerant temperature sensor 42 is attached to a communication portion from the refrigerant heater 30 to the accumulator 6. The control circuit is shown in FIG. The outdoor unit A includes an outdoor controller 50. The outdoor control unit 50 includes a microcomputer and its peripheral circuits, and controls the entire outdoor unit A.

The outdoor control unit 50 is provided with an electronic expansion valve 11,
21, electronic flow rate control valve 7, proportional valve 33, igniter 34, flame detector 35, combustion fan motor 32M, four-way valve 2,
Outdoor fan motor 9M, refrigerant temperature sensor 16, 17, 2
6, 27, 41, 42, the two-way valves 13, 28, 8 and the inverter circuit 51 are connected.

The inverter circuit 51 includes a commercial AC power source 52.
Is rectified, converted into an AC voltage having a predetermined frequency and level according to a command from the outdoor control unit 50, and output. This output is supplied to the compressor motor 1M as driving power. The indoor unit B1 includes an indoor controller 60. The indoor control unit 60 is composed of a microcomputer and its peripheral circuits, and controls the entire indoor unit B1.

The indoor temperature sensor 6 is attached to the indoor control unit 60.
1, a heat exchanger temperature sensor 15, a remote control operation unit (hereinafter abbreviated as a remote controller) 62, and an indoor fan motor 14M are connected. The indoor unit B2 includes an indoor controller 60. The indoor control unit 60 is composed of a microcomputer and its peripheral circuits, and controls the entire indoor unit B2. The indoor control unit 60 includes an indoor temperature sensor 61, a heat exchanger temperature sensor 25, a remote controller 62, and an indoor fan motor 24.
Connect M. Then, the indoor control units 60, 60 are connected to the outdoor control unit 50 by the power supply line ACL and the serial signal line SL, respectively. The indoor control units 60, 60 are
The following functional means are provided. (1) A means for sending an operation mode command or set room temperature data by operating the remote controller 62 to the outdoor control section 50 by a serial signal synchronized with the power supply voltage.

(2) The outdoor controller 50 detects the difference between the detected temperature of the indoor temperature sensor 61 and the set indoor temperature of the remote controller 62 (that is, the air conditioning load), and uses it as a required capacity and a serial signal synchronized with the power supply voltage. Means to send to. (3) A means for sending the temperature data detected by the heat exchanger temperature sensors 15 and 25 to the outdoor control unit 50 by a serial signal synchronized with the power supply voltage. The outdoor control unit 50 includes the following functional means.

(1) Based on the cooling operation mode command from the indoor units B1 and B2, the refrigerant discharged from the compressor 1 is supplied with a four-way valve 2, an outdoor heat exchanger 3, a check valve 4, and an electronic expansion valve 1.
1, 21, indoor heat exchangers 12, 22, two-way valves 13, 2
3, means for flowing through the four-way valve 2, the check valve 5, and the accumulator 6 to execute the cooling operation. (2) A means for controlling the capacity of the compressor 1 (= output frequency F of the inverter circuit 51) during the cooling operation in accordance with the sum of the required capacities of the indoor units B1 and B2.

(3) Means for opening the two-way valve corresponding to the one of the two-way valves 13, 23 having a larger required capacity of the indoor units B1, B2 during the cooling operation and closing the two-way valve corresponding to the smaller one .

(4) Indoor units B1 and B during cooling operation
Refrigerant evaporation temperature at 2 (= heat exchanger temperature sensor 15, 25
Opening the flow rate adjusting valve 7 so that the difference (or ratio) between the detected temperatures Tc1 and Tc2 has a predetermined relationship (= value corresponding to the ratio or difference in required capacity) based on the required capacity of the indoor units B1 and B2. A means to control the degree.

(5) Indoor heat exchangers 12 and 2 during cooling operation
A means for detecting the degree of refrigerant superheat at 2 (= difference between the temperature detected by the heat exchanger temperature sensors 15 and 25 and the temperature detected by the refrigerant temperature sensors 16 and 26). (6) A means for controlling the opening degree of the electronic expansion valves 11 and 21 so that the detected refrigerant superheats have constant values.

(7) Based on the heating operation mode command from the indoor units B1 and B2, the refrigerant discharged from the compressor 1 is supplied with the four-way valve 2, the two-way valves 13 and 23, and the indoor heat exchangers 12 and 2.
2, electronic expansion valves 11, 21, two-way valve 8, refrigerant heater 3
0, means for flowing through the accumulator 6 to perform heating operation.

(8) During this heating operation, the capacity of the compressor 1 (= output frequency F of the inverter circuit 51) and the heating amount of the refrigerant heater 30 (= combustion amount of the gas burner 31) are requested by the indoor units B1 and B2. A means of controlling according to the sum of abilities.

(9) Means for opening the two-way valve corresponding to the one of the two-way valves 13, 23 having a larger required capacity of the indoor units B1, B2 during the heating operation and closing the two-way valve corresponding to the smaller one .

(10) During the heating operation, the indoor heat exchanger 12,
Temperature of refrigerant flowing into 22 (= refrigerant temperature sensor 16, 2
The difference (or ratio) between Tg1 and Tg2 (detected temperature of 6) is based on the required capacity of the indoor units B1 and B2 (=
A means for controlling the opening degree of the flow rate adjusting valve 7 so that the ratio becomes a value according to the ratio or difference of the required capacity.

(11) During this heating operation, the degree of supercooling in each of the indoor heat exchangers 12, 22 is detected, and the total opening of the electronic expansion valves 11, 21 is made constant so that the degree of supercooling becomes equal. A means for opening one of the electronic expansion valves 11 and 21 by a certain amount and closing the other valve by a certain amount so as to keep it.

(12) During heating operation, the degree of refrigerant superheat ΔTe in the refrigerant heater 30 (= the temperature T detected by the refrigerant temperature sensor 42).
A means for detecting the difference between eo and the temperature Tei detected by the refrigerant temperature sensor 41. (13) A means for controlling the opening degree of the electronic expansion valves 11 and 21 so that the detected refrigerant superheat degree becomes a predetermined value. Next, the action of the operation will be described.

It is assumed that the cooling operation mode and the desired indoor temperature are set by the remote controller 62 of the indoor unit B1 and the operation start operation is performed. The operation of the indoor unit B2 will be stopped. In this case, the operating side two-way valve 13
Open and close the two-way valve 23 on the stop side. Further, the flow rate adjusting valve 7 is fully closed.

Then, the compressor 1 is started, and the refrigerant discharged from the compressor 1 is supplied with the four-way valve 2, the outdoor heat exchanger 3, the electronic expansion valve 11, the indoor heat exchanger 12, as shown by the solid arrow in FIG. It flows through the two-way valve 13, the four-way valve 2, the check valve 5, and the accumulator 6 to start the independent cooling operation of the indoor unit B1.

During this cooling alone operation, the capacity of the compressor 1 (=
The output frequency F) of the inverter circuit 51 is set to the indoor unit B
Control according to the required capacity of 1. Further, the degree of refrigerant superheat in the indoor heat exchanger 12 (= the difference between the temperature detected by the heat exchanger temperature sensor 15 and the temperature detected by the refrigerant temperature sensor 16) is detected so that the detected degree of refrigerant superheat becomes a constant value. The opening degree of the electronic expansion valve 11 is controlled.

Further, it is assumed that the heating operation mode and the desired indoor temperature are set by the remote controller 62 of the indoor unit B1 and the operation start operation is performed. The indoor unit B
No. 2 will be stopped. In this case, the two-way valve 13 on the driving side is opened and the two-way valve 23 on the stop side is closed. further,
The flow rate adjusting valve 7 is fully closed.

Then, the compressor 1 is started, and the refrigerant discharged from the compressor 1 is transferred to the four-way valve 2, the two-way valve 13, the indoor heat exchanger 12, the electronic expansion valve 11, the two as shown by the broken line arrow in FIG. It flows through the one-way valve 8, the refrigerant heater 30, and the accumulator 6 to start the independent heating operation of the indoor unit B1.

During this heating alone operation, the capacity of the compressor 1 (=
The output frequency F of the inverter circuit 51 and the heating amount of the refrigerant heater 30 (= the combustion amount of the gas burner 31) are controlled according to the required capacity of the indoor unit B1. Further, the degree of refrigerant superheat ΔTe (= refrigerant temperature sensor 42 in the refrigerant heater 30)
Difference between the detected temperature Teo and the detected temperature Tei of the refrigerant temperature sensor 41) is detected, and the opening degree of the electronic expansion valve 11 is controlled so that the detected refrigerant superheat degree ΔTe becomes a predetermined value. On the other hand, it is assumed that the remote controller 62 of each of the indoor units B1 and B2 sets the cooling operation mode and the desired indoor temperature, and the operation start operation is performed.

In this case, if the difference in required capacity between the indoor units B1 and B2 is different, the two-way valve 13 on the side with the larger required capacity, for example, the indoor unit B1 side is opened, and the two with the smaller required capacity, for example, the indoor unit B2 side. The way valve 23 is closed.

Then, the compressor 1 is started, and the refrigerant discharged from the compressor 1 is supplied with the four-way valve 2, the outdoor heat exchanger 3, the electronic expansion valves 11, 21 and the indoor heat exchanger as shown by the solid line arrow in FIG. 1
2, 22, the flow rate control valve 7, the two-way valve 13, the four-way valve 2, the check valve 5, and the accumulator 6 to allow the indoor units B1 and B2 to start cooling parallel operation. During this cooling parallel operation, the capacity of the compressor 1 (= output frequency F of the inverter circuit 51) is controlled according to the total capacity required of the indoor units B1 and B2.

Furthermore, the absolute value ΔTc of the difference between the refrigerant evaporation temperatures (= the temperature detected by the heat exchanger temperature sensors 15 and 25) Tc1 and Tc2 in the indoor units B1 and B2 is the ratio of the required capacity of the indoor units B1 and B2. According to the specified value,
The opening degree of the flow rate adjusting valve 7 is controlled.

By controlling the opening degree of the flow rate adjusting valve 7, the amount of the refrigerant flowing into the indoor unit B2 having the smaller required capacity is set to an appropriate state corresponding to the required capacity. As a result, the amount of the refrigerant flowing through the indoor unit B1 is set to an appropriate state corresponding to the required capacity of the indoor unit B1.

The degree of refrigerant superheat in the indoor heat exchangers 12 and 22 (= the difference between the temperature detected by the heat exchanger temperature sensors 15 and 25 and the temperature detected by the refrigerant temperature sensors 16 and 26) is detected,
The opening degrees of the electronic expansion valves 11 and 21 are controlled so that the detected refrigerant superheats have constant values.

In this case, since a sufficient amount of the refrigerant is flowing in the indoor unit B1 on the side having a large required capacity,
The refrigerant superheat control by the electronic expansion valve 11 works effectively, and the refrigerant superheat in the indoor heat exchanger 12 can be always maintained constant.

Moreover, since an appropriate and sufficient amount of the refrigerant is flowing also to the indoor unit B2 on the side of which the required capacity is small, the refrigerant superheat control by the electronic expansion valve 21 works effectively, and the indoor heat exchanger 22 operates. The degree of superheat of the refrigerant can always be kept constant. Therefore, the refrigeration cycle becomes stable, and proper cooling capacity can be obtained. By the way, in this cooling parallel operation, the required capacities of the indoor units B1 and B2 may be almost the same.

In this case, the refrigerant evaporation temperatures (= detected temperatures of the heat exchanger temperature sensors 15 and 25) Tc1 and Tc2 in the indoor units B1 and B2 are monitored, and the larger one of the two, for example, the indoor unit B1 side, is monitored. The one-way valve 13 is closed and the smaller one, for example, the two-way valve 23 on the indoor unit B2 side is opened. The relationship of opening / closing of the two-way valves 13 and 23 here is opposite to the case of different required capacities.

Further, the opening of the flow rate adjusting valve 7 is controlled so that the absolute value ΔTc of the difference between the refrigerant evaporation temperatures Tc1 and Tc2 becomes substantially zero. By controlling the opening of the flow rate adjusting valve 7, an appropriate amount of refrigerant is distributed to the indoor units B1 and B2.

Next, it is assumed that the heating operation mode and the desired indoor temperature are set by the remote controllers 62 of the indoor units B1 and B2, respectively, and the operation start operation is performed. This operation will be described with reference to the flowcharts of FIGS.

First, if the difference between the required capacities of the indoor units B1 and B2 is larger than the set value, the two-way valve 13 on the side with the larger required capacity, for example, the indoor unit B1 side is opened, and the side with the smaller required capacity, for example, the indoor unit B2 side. The two-way valve 23 is closed.

Then, the compressor 1 is started, and the refrigerant discharged from the compressor 1 is supplied with the four-way valve 2, the two-way valve 13, the flow rate adjusting valve 7, the indoor heat exchangers 12, 22 as shown by the broken line arrows in FIG. , The electronic expansion valves 11 and 21, the two-way valve 8, the refrigerant heater 30, and the accumulator 6, and the indoor units B1 and B2.
Starts parallel heating operation.

During this heating parallel operation, the capacity of the compressor 1 (=
The output frequency F of the inverter circuit 51) and the heating amount of the refrigerant heater 30 (= combustion amount of the gas burner 31) are controlled according to the total required capacity of the indoor units B1 and B2.

Further, the absolute value ΔTg of the difference between the temperatures (= the temperatures detected by the refrigerant temperature sensors 16 and 26) Tg1 and Tg2 of the refrigerant flowing into the indoor heat exchangers 12 and 22 is the ratio of the required capacity of the indoor units B1 and B2. To a predetermined value according to
The opening degree of the flow rate adjusting valve 7 is controlled.

By controlling the opening of the flow rate adjusting valve 7, the amount of the refrigerant flowing through the indoor unit B2 on the side having the smaller required capacity is set to an appropriate state corresponding to the required capacity. As a result, the amount of the refrigerant flowing through the indoor unit B1 is set to an appropriate state corresponding to the required capacity of the indoor unit B1.

The degree of supercooling of the indoor heat exchanger 12 (difference between the temperature Tc1 detected by the heat exchanger temperature sensor 15 and the temperature ω1 detected by the refrigerant temperature sensor 17) and the degree of supercooling of the indoor heat exchanger 22 (heat The difference ΔT between the temperature Tc2 detected by the exchanger temperature sensor 25 and the temperature ω2 detected by the refrigerant temperature sensor 27) is calculated.

If the opening degree of the electronic expansion valve 11 or 12 is equal to or less than the set angle (for example, the full opening or the opening close to the full opening), the indoor heat exchange with the larger degree of supercooling so that the value of ΔT becomes zero. Of the electronic expansion valve 21 connected to the heat exchanger 22, that is, the indoor heat exchanger 22, and the other electronic expansion valve 1 is opened.
A certain amount of opening 1 is closed. As a result, it is possible to prevent the refrigerant from accumulating in the indoor heat exchanger 22 on the side having a small heating required capacity, and the refrigerant circulation amount in the entire refrigeration cycle does not become insufficient.

Further, by closing the opening degree of the other electronic expansion valve 11 by a certain amount, the total opening degree of the electronic expansion valves 11 and 21 is kept constant and the degree of refrigerant superheat ΔTe in the refrigerant heater 30.
Is controlled so as not to affect the control.

By the way, the opening of the electronic expansion valve 21 connected to the indoor heat exchanger 22 having the larger degree of supercooling is controlled so that the value of ΔT becomes zero, and the electronic expansion is performed. When the opening of the valve 21 is equal to or larger than the set opening and the state where the difference ΔT in the degree of subcooling is equal to or larger than the set value continues for a certain period of time, the flow rate adjusting valve 7 is opened by a certain amount.

By doing so, the electronic expansion valve 2
Even when the opening degree of 1 is controlled, the degree of supercooling ΔTe in the refrigerant heater 30 does not decrease even if the difference ΔT in supercooling degree cannot be reduced to zero.
Can be controlled to be a predetermined value.

The degree of refrigerant superheat ΔT in the refrigerant heater 30
e (= the difference between the detected temperature Teo of the refrigerant temperature sensor 42 and the detected temperature Tei of the refrigerant temperature sensor 42) is detected, and the total opening degree of the electronic expansion valves 11 and 21 is adjusted so that the detected refrigerant superheat degree becomes a constant value. To control. By the way, in this heating parallel operation, the difference between the required capacities of the indoor units B1 and B2 may be less than the set value. In this case both two-way valves 1
Open 3,23. Then, the total opening degree of the electronic expansion valves 11 and 21 is controlled so that the detected refrigerant superheat degree ΔTe becomes a predetermined value. The present invention can also be applied to an air conditioner having a refrigerating cycle as shown in FIG. 5, which is not equipped with the refrigerant heater 30.

Further, as shown in FIG. 6, the refrigerant heater 30
, And a plurality of indoor heat exchangers 12, 22, ..., Gas flow pipes G1, G2, ... Between the respective outdoor heat exchangers 12, 22 ,. The same can be applied to an air conditioner having a refrigeration cycle provided with, .... In such an air conditioner, ΔT
By controlling the opening of any one of the electronic expansion valves 11, 12, ... Connected to the indoor heat exchanger with the higher degree of supercooling so that the value of When the opening of a certain electronic expansion valve becomes equal to or larger than the set opening and the state where the difference ΔT in supercooling degree is equal to or larger than the set value continues for a certain period of time, the flow rate adjusting valves 81, 82, ... It suffices to open the selected flow rate adjusting valve by a fixed amount.

[0062]

As described above in detail, according to the present invention, by keeping the degree of subcooling of each indoor unit constant during the heating operation, even if there is a large difference in the heating demand between the indoor units, the heat source side outdoor It is possible to provide an air conditioner that can always ensure an appropriate heating capacity by controlling the degree of refrigerant superheat in a heat exchanger to a predetermined value.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a refrigeration cycle according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a control circuit of the same embodiment.

FIG. 3 is a flowchart for explaining the operation of the embodiment.

FIG. 4 is a flowchart for explaining the operation of the embodiment.

FIG. 5 is a diagram showing a configuration of a refrigeration cycle according to another embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a refrigeration cycle according to another embodiment of the present invention.

[Explanation of symbols]

A ... Outdoor unit, B1, B2 ... Indoor unit, 1 ... Compressor, 3 ... Outdoor heat exchanger, 11, 21 ... Electronic expansion valve, 1
2, 22 ... Indoor heat exchanger, 7 ... Electronic flow rate adjusting valve, 13,
23 ... Two-way valve, 30 ... Refrigerant heater, 50 ... Outdoor control unit.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigeto Sumitani             336 Tatehara, Fuji City, Shizuoka Prefecture Toshiba Corporation             Inside the Fuji factory

Claims (2)

[Claims] 1. A compressor, a four-way valve, a plurality of indoor heat exchangers connected in parallel, an electronic expansion valve provided in each liquid pipe communicating with each indoor heat exchanger, and a heat source side outdoor heat exchanger are connected. Together with the indoor heat exchanger, a flow rate adjusting device that is provided in a gas pipe between the indoor heat exchanger and the four-way valve and adjusts a refrigerant flow rate to each indoor heat exchanger is provided. In an air conditioner composed of a refrigeration cycle, the refrigerant discharged from the compressor is supplied with a four-way valve, each indoor heat exchanger,
Each electronic expansion valve, means for performing a heating operation by flowing through the outdoor heat exchanger, means for controlling the capacity of the compressor and the like according to the sum of the required capacity of each indoor unit during the heating operation, A means for detecting the degree of refrigerant superheat in the outdoor heat exchanger, a means for controlling the total opening degree of each of the electronic expansion valves so that the detected degree of refrigerant superheat has a predetermined value, and a degree of superheat in each indoor heat exchanger. The opening degree of each electronic expansion valve is controlled to be opened and closed while keeping the total opening degree of each electronic expansion valve constant so that the degree of supercooling in each indoor heat exchanger becomes equal to the means for detecting the cooling degree. An air conditioner comprising: 2. A compressor, a four-way valve, a plurality of indoor heat exchangers connected in parallel, an electronic expansion valve provided in each liquid pipe communicating with each indoor heat exchanger, and a heat source side outdoor heat exchanger are connected. Together with the indoor heat exchanger, a flow rate adjusting device that is provided in a gas pipe between the indoor heat exchanger and the four-way valve and adjusts a refrigerant flow rate to each indoor heat exchanger is provided. In an air conditioner composed of a refrigeration cycle, the refrigerant discharged from the compressor is supplied with a four-way valve, each indoor heat exchanger,
Each electronic expansion valve, means for performing a heating operation by flowing through the outdoor heat exchanger, means for controlling the capacity of the compressor and the like according to the sum of the required capacity of each indoor unit during the heating operation, A means for detecting the degree of refrigerant superheat in the outdoor heat exchanger, a means for controlling the total opening degree of each of the electronic expansion valves so that the detected degree of refrigerant superheat is a predetermined value, and a temperature for each indoor heat exchanger. The opening degree of each electronic expansion valve is controlled to be opened and closed while keeping the total opening degree of each electronic expansion valve constant so that the degree of cooling and the degree of supercooling in each indoor heat exchanger become equal. Means and means for controlling the flow rate adjusting device to increase the flow rate of the one having a larger required capacity when the difference in the required capacity between the indoor heat exchangers is larger than a set value, and the large side of the electronic expansion valve. Heat exchange in each room when the opening of is above the set value Of if the difference supercooling degree elapses more than the set value of the state a predetermined time or more, the air conditioner is characterized in that the opening of the flow control device and a control means for a predetermined amount open.