JPH0484080A - Air conditioner - Google Patents

Abstract

PURPOSE:To assure a necessary and sufficient capability of a cooling side indoor device and a heating side indoor device even if an outdoor device is placed at a location higher than the indoor devices by a method wherein a pressure of refrigerant passing through a liquid pipe and another pressure of refrigerant passing through a high pressure gas pipe are detected and an amount of refrigerant passing through the liquid is controlled in such a way as a difference of detected pressures is set within a specified range. CONSTITUTION:An outdoor device A is placed at a location higher than those of indoor devices C1 to C4. A required amount of refrigerant flows in the cooling side indoor devices C1 and C2. Refrigerant hardly flows in the heating side indoor device C3. Due to this fact, PMV 16 is set to a predetermined degree of opening. When a heating degree of refrigerant becomes a stable state, a pressure of refrigerant passing through a liquid pipe W is detected by a pressure sensor 61, a pressure of refrigerant passing through a high pressure gas pipe G is detected by a pressure sensor 62 and then a difference DELTAP of both detected pressures is detected. PMV 16 is decreased by a specified amount until the pressure difference DELTAP is converted to a substantial zero value within a predetermined value. A refrigerant pressure within a liquid pipe W is adjusted to a substantial same value as that of the refrigerant in a high pressure gas pipe G, and then the capabilities of the cooling indoor devices C1, C2 and the heating indoor device C3 can be assured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a multi-system air conditioner capable of air conditioning multiple rooms.

(Prior Art) Generally, a multi-system air conditioner includes one outdoor unit and a plurality of indoor units, and the indoor unit and the outdoor unit are connected by piping via a branch unit.

The branch unit communicates with the outdoor unit via a liquid pipe, a high-pressure side gas pipe, and a low-pressure side gas pipe, and switches the flow direction of refrigerant to each indoor unit.

That is, by selecting the flow direction of the refrigerant to each indoor unit using the branch unit, it is possible to perform simultaneous cooling and heating operations in each indoor unit.

An example of this air conditioner is shown in FIG.

In the figure, A is an outdoor unit, and a branch unit B is communicated with this outdoor unit A via a liquid pipe W, a high pressure side gas pipe G, and a low pressure side gas pipe S, and a plurality of indoor units CI r are connected to the branch unit B. C2r C3°C4 are connected.

The outdoor unit A includes two variable capacity compressors 1 and 2.

A common discharge pipe 4 is connected to the discharge ports of the compressors 1, 2 via a check valve 3.3. A common suction pipe 5 is connected to the suction port of the compressor 1.2, and a liquid tank 6 is provided in the suction pipe 5.

The discharge pipe 4 is branched into two discharge pipes 4a and 4b.

The suction pipe 5 is branched into two suction pipes 5a and 5b on the upstream side of the liquid tank 6.

An oil separator 7 is provided at the discharge port of the compressor 1, and an oil bypass 8 is provided from the oil separator 7 to the suction port of the compressor 1.

Similarly, an oil separator 7 is provided at the discharge port of the compressor 2, and an oil bypass 8 is provided from the oil separator 7 to the suction port of the compressor 2.

An outdoor heat exchanger 10 is connected to the discharge pipe 4a via a three-way valve 9.
is connected. A liquid tank 13 is connected to the outdoor heat exchanger 10 via a parallel circuit of a heating expansion valve 11 and a check valve 12, and a liquid pipe W is connected to the liquid tank 13.

The suction pipe 5b is connected to the pipe between the two-way valve 9 and the outdoor heat exchanger 10 via a two-way valve 14 and a check valve 15.

The liquid pipe W has an electronic flow rate adjustment valve (
Pulse motor valve; hereinafter abbreviated as PMV') 21,
Air conditioning expansion valve 22.32,4 via 31,41.51
2.52 is connected. This expansion valve 22, 32, 4
A check valve 23.33.43.53 is connected in parallel to 2.52.

The expansion valves 22, 32, 42.52 include indoor units c,
+C2r C3+C4 indoor heat exchanger 24°34.44.54 is connected.

A low pressure side gas pipe S is connected to the indoor heat exchangers 24, 34, 44.54 via two-way valves 25, 35, 45.45 of branch unit B, and also a two-way valve of branch unit B. 26, 36, 46° 56 to high pressure side gas pipe G
is connected.

The low pressure gas pipe S is an extension of the suction pipe 5a.

The high-pressure gas pipe G is an extension of the discharge pipe 4b.

Explain the action.

Indoor unit C1 is in cooling operation mode, indoor unit C2
It is assumed that the indoor unit C3 is in the cooling operation mode, the indoor unit C3 is in the heating operation mode, and the indoor unit C4 is stopped. and,
Assume that the total required cooling capacity is greater than the total required heating capacity.

In this case, the cooling main operation mode is determined, the two-way valve 9 of the outdoor unit A is opened (displayed in white), the two-way valve 14 is closed (displayed in black), and the outdoor heat exchanger 10 is connected to the discharge pipe 4a. Ru.

In branch unit B, PMV21, 31.41 opens, PMV51 closes (white display), and two-way valve 25
, 35, 46 are open (white display), and two-way valves 45, 5 are open (displayed in white).
5, 26, 36, and 56 are closed (displayed in black), the gas pipes communicating with the indoor units C1 and C2 in cooling operation mode are connected to the low-pressure side gas pipe S (intake pipe 5a), and the indoor units in heating operation mode A gas pipe communicating with C3 is connected to the high pressure side gas pipe G (discharge pipe 4b).

The device consisting of the compressors 1 and 2 thus enters the outdoor heat exchanger 10 through the two-way valve 9.

In this outdoor heat exchanger 10, the refrigerant condenses. The refrigerant that has passed through the outdoor heat exchanger 10 passes through the check valve 12 and liquid tank 13, and then passes through the PMV 21° 31 and the expansion valve 22.
．． 32 and enters the indoor units C, , C2. In this indoor unit C1r02, the refrigerant is vaporized. The refrigerant that has passed through the indoor units C1 and C2 passes through the two-way valves 25 and 35 and the low-pressure side gas pipe S, and is sucked into the compressors 1 and 2.

At the same time, some of the refrigerant discharged from the compressor 1.2 passes through the high-pressure gas pipe G and the two-way valve 46 to the indoor unit C.
Enter 3. In this indoor unit C3, the refrigerant condenses. The refrigerant that has passed through the indoor unit C3 passes through the check valve 43 and P
Passing through MV41, indoor units C,,c2 (PMV2
1, 31).

That is, the outdoor heat exchanger 10 is a condenser, and the indoor heat exchanger 2 is a condenser.
4.34 works as an evaporator, and indoor heat exchanger 44 works as a condenser.

In this case, part of the heat absorbed by the cooling indoor unit CI+C2 is used as heat radiation from the heating indoor unit C3.

Next, the indoor unit C1 requests the heating operation mode, the indoor unit C2 requests the heating operation mode, and the indoor unit C
Assume that the request No. 3 is for the cooling operation mode and the indoor unit C4 is to stop operating. It is also assumed that the total required heating capacity is greater than the total required cooling capacity.

In this case, the heating main operation mode is determined, and as shown in Fig. 8, PMV9 of outdoor unit A is closed (displayed in black).
, the two-way valve 14 opens (displayed in white), and the outdoor heat exchanger 10 is connected to the suction pipe 5b.

In branch unit B, PMV21, 31.41 opens, PMV51 closes (white display), and two-way valve 45
, 26.36 are open (displayed in white), and the two-way valves 25, 3
5, 55, 46, and 56 are closed (displayed in black), the gas pipes communicating with the indoor units C1 and C2 in the heating mode are connected to the high-pressure side gas pipe G (discharge pipe 4b), and the indoor units in the cooling mode are connected to the high-pressure side gas pipe G (discharge pipe 4b). A gas pipe communicating with C3 is connected to the low pressure side gas pipe S (suction pipe 5a).

Therefore, the refrigerant discharged from the compressors 1 and 2 enters the indoor units CI and C2 through the high-pressure side gas pipe G and the two-way valves 26 and 36. In the indoor units C1 and C2, the refrigerant condenses. The refrigerant that has passed through the indoor units C1 and C2 passes through the check valves 23 and 33 and the PMVs 21 and 31.
Next, it passes through the liquid tank 13 and the expansion valve 11 and enters the outdoor heat exchanger 10. In this outdoor heat exchanger 10, the refrigerant is vaporized. The refrigerant that has passed through the outdoor heat exchanger 10 passes through the two-way valve 1
4. Check valve 15. and the suction pipe 5b, the compressor 1,
Sucked into 2.

At the same time, indoor units C1, C2, check valves 23°33,
Part of the refrigerant that has passed through PMV21 and PMV31 is converted to PMV4.
1 and the expansion valve 42 to enter the indoor unit C3.

In this indoor unit C3, the refrigerant is vaporized. The refrigerant that has passed through the indoor unit C3 passes through the three-way valve 45 and the low-pressure side gas pipe S and is sucked into the compressor 1.2.

That is, the heating-side indoor heat exchangers 24 and 34 function as condensers, and the cooling-side indoor unit 44 and outdoor heat exchanger 10 function as evaporators.

In this case, the heat absorbed by the cooling-side indoor unit 44 and the outdoor heat exchanger 10 is used as heat radiation from the heating-side indoor unit C1+02.

(Problems to be Solved by the Invention) In such a multi-system air conditioner, for example, as shown in FIG. 9, an outdoor unit A is installed on the roof of a building, etc., and a branch unit B and an indoor unit are installed. C1, C2°C3, C4 may be installed on the floor or room below.

In this way, the outdoor unit A becomes the indoor unit C1°C21
c3+ If the position is higher than C4, when the refrigerant pressure in the liquid pipe W and the refrigerant pressure in the high pressure side gas pipe G are compared during simultaneous cooling and heating operation in the cooling main operation mode, the outdoor unit A
The pressure is the same at the point where it exits. However, when viewed from the position of the indoor units cl+ C2, C3rC4, the refrigerant pressure in the liquid pipe W is higher than the pressure of the refrigerant passing through the high-pressure side gas pipe G by the head difference.

In this case, the required amount of refrigerant flows into the cooling indoor unit, but it becomes difficult for the refrigerant to flow into the heating indoor unit.

Therefore, although sufficient cooling capacity can be ensured, the heating capacity is only about 115 times the cooling capacity.

This invention takes the above-mentioned circumstances into consideration, and both the air conditioner of claim 1 and the air conditioner of claim 2 are arranged so that even if the outdoor unit is located at a higher position than the indoor unit, the cooling side indoor unit and the heating side The purpose is to ensure necessary and sufficient capacity in each side indoor unit.

[Means for solving the structure of the invention] The air conditioner according to claim 1 comprises one outdoor unit having a compressor and an outdoor heat exchanger, and a plurality of outdoor units each having an indoor heat exchanger. The indoor unit is connected to the outdoor unit through a liquid pipe, a high-pressure side gas pipe, and a low-pressure side gas pipe, and a branching unit is configured to switch the flow direction of refrigerant to each of the indoor units, thereby controlling the flow of refrigerant to each indoor unit. In a multi-system air conditioner that enables simultaneous operation of cooling and heating in each indoor unit by selecting a direction, means for detecting the pressure of refrigerant passing through the liquid pipe;
means for detecting the pressure of the refrigerant passing through the high pressure side gas pipe;
and means for controlling the amount of refrigerant passing through the liquid pipe so that the difference between these detected pressures falls within a certain range.

An air conditioner according to a second aspect of the present invention includes one outdoor unit having a compressor and an outdoor heat exchanger, a plurality of indoor units each having an indoor heat exchanger, and a liquid pipe and a high-pressure gas side connected to the outdoor unit. The branch unit communicates with the pipe and the low-pressure side gas pipe to switch the flow direction of the refrigerant to each indoor unit, and by selecting the flow direction of the refrigerant to each indoor unit, cooling and heating can be performed in each indoor unit. In a multi-system air conditioner that enables simultaneous operation of , and means for controlling at least one of the amounts of refrigerant flowing into the liquid pipe so that the detection result falls within a certain range.

(Function) In the air conditioner according to claim 1, the pressure of the refrigerant passing through the liquid pipe and the pressure of the refrigerant passing through the high pressure side gas pipe are detected, respectively.
In the air conditioner according to claim 2, the amount of refrigerant passing through the liquid pipe is controlled so that the difference between the two detected pressures is within a certain range. At least one of the amount of refrigerant flowing, the amount of refrigerant flowing to the heating-side indoor unit, and the amount of refrigerant flowing to the liquid pipe is controlled so that the detection result falls within a certain range.

(Example) Hereinafter, a first example of the present invention will be described with reference to the drawings. This first embodiment corresponds to the air conditioner of claim 1. In the drawings, the same parts as in FIGS. 7 to 9 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

As shown in FIG. 1, in the outdoor unit A, a PMV 16 is provided in a pipe leading from the outdoor heat exchanger 10 to the check valve 12.

Furthermore, in branch unit B, the following configuration is applied.

A pressure sensor 61 is attached to the liquid pipe W.

A pressure sensor 62 is attached to the high pressure side gas pipe G.

The control circuit is shown in FIG.

The outdoor unit A includes an outdoor control section 7o consisting of a microcomputer and its peripheral circuits.

This outdoor control unit 70 includes inverter circuits 71, 72, P
Connect MV16 and Oyohi two-way valve 9.14.

The inverter circuits 71 and 72 rectify the voltage of the AC power supply 73, convert it into an AC voltage of a predetermined frequency (and level) according to a command from the outdoor control unit 7o,
This is to supply driving power to M and 2M, respectively.

Branch unit B includes a multi-control unit 8o consisting of a microcomputer and its peripheral circuits. The PMVs 21, 31° 41, 51, two-way valves 25, 35, 45, 55° 26, 36, 46, 56, and pressure sensors 61° 62 are connected to the KonoMulti control unit 80.

The indoor units C1, C2'+ C3+ C4 each include an indoor control section 90 consisting of a microcomputer and its peripheral circuits. In these indoor control units 90,
A remote control operation unit (hereinafter referred to as a remote control) 91 and an indoor temperature sensor 92 are connected.

The indoor control unit 90 includes the following functional means.

(2) Means for sending a request for a cooling operation mode or a request for a heating operation mode to the multi-control unit 80 based on the operation of the remote control 91.

(2) Means for sending the difference between the indoor temperature set by the remote controller 91 and the temperature detected by the indoor temperature sensor 92 to the multi-control unit 80 as the required cooling capacity (in the cooling operation mode) or the required heating capacity (in the heating operation mode).

In addition, the multi-control unit 80, the outdoor control unit 70, each PMV,
The two-way valves constitute the following functional means:

■Indoor units C1, c2. c3. Means for determining the cooling main operation mode when the sum of the cooling capacities requested from any of c4 is larger than the sum of the heating capacities also requested.

■When the cooling main operation mode is determined, the refrigerant discharged from the compressor 1.2 is passed through the outdoor heat exchanger 10, and then passed through the indoor unit that is requesting the cooling operation mode.
means to return to.

■When the cooling main operation mode is determined, a part of the refrigerant discharged from the compressor 1゜2 is passed through the indoor unit that is requesting the heating operation mode, and then to the indoor unit that is requesting the cooling operation mode. means for joining the refrigerant flow.

■When the cooling main operation mode is determined, the number of operating compressors 1 and 2 and the operating frequency (
means for controlling the output frequency of the inverter circuits 71 and 72;

■When the cooling main operation mode is determined, the difference Δ between the detected pressure Pw of the pressure sensor 61 and the detected pressure Pg of the pressure sensor 62
Means for detecting P.

(2) Means for controlling the amount of refrigerant passing through the liquid pipe W so that the detected pressure difference ΔP falls within a certain range (ΔP≦ΔP+).

(2) Means for determining the heating main operation mode when the sum of the heating capacities required from any of the indoor units C, C2, C3, and C4 is greater than the sum of the cooling capacities also requested.

■When the heating main operation mode is determined, the refrigerant discharged from the compressor 1.2 is passed through the indoor unit that is requesting the heating operation mode, and then passed through the outdoor heat exchanger 10 to the compressor 1.2.
means to return to.

■When the heating main operation mode is determined, part of the refrigerant that has passed through the indoor unit that is requesting the heating operation mode is passed through the indoor unit that is requesting the cooling operation mode, and then passed to the compressors 1 and 2. means of returning.

[Phase] When the heating main operation mode is determined, when the heating main operation mode is determined, the number of operating compressors 1.2 and operating frequency (output frequency of the inverter circuits 71 and 72) according to the total required heating capacity. means to control.

Next, the operation of the above configuration will be explained with reference to the flowchart of FIG. 3.

Indoor unit C1 is in cooling operation mode, indoor unit C2
It is assumed that the indoor unit C3 is in the cooling operation mode, the indoor unit C3 is in the heating operation mode, and the indoor unit C4 is stopped. and,
Assume that the total required cooling capacity is greater than the total required heating capacity.

In this case, the cooling main operation mode is determined and the outdoor unit A
Opens the two-way valve 9 (displayed in white) and closes the two-way valve 14 (displayed in black), thereby connecting the outdoor heat exchanger 10 to the discharge pipe 4.
Connect to a.

In branch unit B, PMV21, 31.41 is opened and PMV51 is closed (displayed in white), and two-way valve 25
, 35, 46 open (white display), and two-way valve 45, 5
5, 26, 36, and 56 (displayed in black), connect the gas pipes of the indoor units C1 and C2 in the cooling operation mode to the low-pressure side gas pipe S (intake pipe 5a), and connect the gas pipes of the indoor unit C3 in the heating operation mode. Connect the pipe to the high pressure side gas pipe G (discharge pipe 4b).

The refrigerant discharged from the compressor 1.2 thus enters the outdoor heat exchanger 10 through the two-way valve 9.

In this outdoor heat exchanger 10, the refrigerant condenses. The refrigerant that has passed through the outdoor heat exchanger 10 passes through the check valve 12 and liquid tank 13, and then passes through the PMV 21° 31 and the expansion valve 22.
．． 32, and the indoor unit c1. Enter c2. In this indoor unit C1C2, the refrigerant is vaporized. The refrigerant that has passed through the indoor unit F C1*C2 passes through the two-way valve 25, 35 and the low-pressure side gas pipe S, and is sucked into the compressors 1 and 2.

At the same time, a part of the refrigerant discharged from the compressor 1.2 passes through the high pressure side gas pipe G and the two-way valve 46 to the indoor unit C.
Enter 3. In this indoor unit C3, the refrigerant condenses. The refrigerant that has passed through the indoor unit C3 passes through the check valve 43 and P
Passing through MV41, indoor units C1, C2 (PMVl1
, 31).

That is, the outdoor heat exchanger 10 is a condenser, and the indoor heat exchanger 2 is a condenser.
4.34 works as an evaporator, and indoor heat exchanger 44 works as a condenser.

In this case, part of the heat absorbed by the cooling indoor units C1 and C2 is used as heat radiation from the heating indoor unit C3.

The number of operating compressors 1.2 and the operating frequency (output frequency of inverter circuits 71, 72) are determined according to the total required cooling capacity.

The opening degree of the PMV 21 is controlled according to the required cooling capacity of the indoor unit C1 in the cooling operation mode, and the amount of refrigerant flowing into the indoor heat exchanger 24 is adjusted.

The opening degree of the PMV 31 is controlled according to the required cooling capacity of the indoor unit C2 in the cooling operation mode, and the amount of refrigerant flowing into the indoor heat exchanger 34 is adjusted.

Regarding the indoor unit C3 in the heating operation mode, the corresponding PMV 41 is set to full open.

Here, outdoor unit A is indoor unit C1°C21c
3+ If the position is higher than C4, in the above cooling main operation mode, although the refrigerant pressure in the liquid pipe W and the refrigerant pressure in the high pressure side gas pipe G are the same at the position where they exit the outdoor unit A, Indoor unit) C1+ C2r C31
When viewed at the position C4, the refrigerant pressure in the liquid pipe W is higher than the pressure of the refrigerant passing through the high-pressure side gas pipe G by the head difference.

In this case, although a necessary amount of refrigerant flows through the cooling-side indoor units C1 and C2, it becomes difficult for the refrigerant to flow into the heating-side indoor unit C3. Therefore, although sufficient cooling capacity can be ensured, a situation arises in which heating capacity is only about 115 of the cooling capacity.

Therefore, the control shown in FIG. 3 is executed.

At the start of cooling main operation mode, PMVl of outdoor unit A
6 is first set to a predetermined initial opening degree.

After the start of operation, 1 fixed time t1 during which the degree of superheating of the refrigerant becomes stable
After , the pressure Pw of the refrigerant passing through the liquid pipe W is detected by the pressure sensor 61, the pressure Pg of the refrigerant passing through the high-pressure side gas pipe G is detected by the pressure sensor 62, and the difference ΔP between the two detected pressures is detected. .

If the detected pressure difference ΔP is not approximately zero within the constant value ΔP1, the opening degree of PMVl 6 of the outdoor unit A is reduced by a predetermined value (several pulses).

When the opening degree of PMV16 decreases, the amount of refrigerant flowing through the liquid pipe W decreases, and a pressure loss occurs in the liquid pipe W.

After a predetermined time t2, the pressure difference ΔP is detected again, and the pressure difference ΔP
PMV until it reaches a value of almost zero within the above constant value ΔP1.
l6 is decreased by a predetermined value.

In this way, as shown in FIG. 9, the outdoor unit A becomes the indoor unit c1. Even if the position is higher than C2, C3, and C4, the refrigerant pressure in the liquid pipe W is adjusted to approximately the same value as the refrigerant pressure in the high-pressure side gas pipe G, and the refrigerant is supplied to the cooling-side indoor units C1+C2 and the heating-side indoor unit C3. can be distributed and supplied in a well-balanced manner.

Therefore, necessary and sufficient capacity can be ensured in each of the cooling-side indoor units CI and C2 and the heating-side indoor unit C3.

Next, a second embodiment of the invention will be described with reference to the drawings. This second embodiment corresponds to the air conditioner of claim 2. In the drawings, the same parts as in FIGS. 1 and 2 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

As shown in FIG. 4, branch unit B has the following configuration.

A temperature sensor 101 is attached to a liquid pipe leading from the expansion valve 22 to the indoor unit C1.

A temperature sensor 102 is attached to a liquid pipe leading from the expansion valve 32 to the indoor unit C2.

A temperature sensor 103 is attached to a liquid pipe leading from the expansion valve 42 to the indoor unit C3.

A temperature sensor 104 is attached to a liquid pipe leading from the expansion valve 52 to the indoor unit C4.

A temperature sensor 105 is attached to the gas pipe leading from the connection of the three-way valve 25, 26 to the indoor unit C1.

A temperature sensor 106 is attached to the gas pipe leading from the connection of the three-way valve 35, 36 to the indoor unit C2.

A temperature sensor 107 is attached to the gas pipe leading from the connection part of the two-way valve 45, 46 to the indoor unit C3.

A temperature sensor 108 is attached to the gas pipe running from the connection part of the two-way valve 55, 56 to the indoor unit C4.

The control circuit is shown in FIG.

PMV21.3 is installed in the multi-control unit 80 of branch unit B.
1,41,51, two-way valve 25,35°45.55,26
, 36, 46, 56, and temperature sensors 101, 102
, 103, 104° 105, 106, 107, 108 are connected.

Then, the multi-control unit 80, the outdoor control unit 70, each PMV
, and each two-way valve constitute the following functional means.

(2) Means for determining the cooling main operation mode when the sum of the cooling capacities requested from any of the indoor units C1, C2, C3, and C4 is greater than the sum of the heating capacities also requested.

■When the cooling main operation mode is determined, the refrigerant discharged from the compressor 1.2 is passed through the outdoor heat exchanger 10, and then passed through the indoor unit that is requesting the cooling operation mode.
means to return to.

■When the cooling main operation mode is determined, a part of the refrigerant discharged from the compressor 1゜2 is passed through the indoor unit that is requesting the heating operation mode, and then to the indoor unit that is requesting the cooling operation mode. means for joining the refrigerant flow.

■When the cooling main operation mode is determined, the number of operating compressors 1 and 2 and the operating frequency (
means for controlling the output frequency of the inverter circuits 71 and 72;

■Means for detecting the degree of refrigerant superheat in the cooling indoor unit when the cooling main operation mode is determined.

■At least one of the following: the amount of refrigerant flowing to the cooling indoor unit, the amount of refrigerant flowing to the heating indoor unit, and the amount of refrigerant flowing to the liquid pipe W so that the detected degree of refrigerant superheating falls within a certain range. means of control.

(2) Means for determining the heating main operation mode when the sum of the heating capacities requested from any of the indoor units C1, C2, C3, and C4 is greater than the sum of the cooling capacities also requested.

■When the heating main operation mode is determined, the refrigerant discharged from the compressor 1.2 is passed through the indoor unit that is requesting the heating operation mode, and then passed through the outdoor heat exchanger 10 to the compressor 1.2.
means to return to.

■When the heating main operation mode is determined, part of the refrigerant that has passed through the indoor unit that is requesting the heating operation mode is passed through the indoor unit that is requesting the cooling operation mode, and then passed to the compressor 1.2. means of returning.

[Co., Ltd.] When the main heating operation mode is determined, the number of operating compressors 1.2 and the operating frequency (output frequency of the inverter circuits 71 and 72) are determined according to the total required heating capacity. means to control.

Next, the operation of the above configuration will be explained with reference to the flowchart of FIG. 6.

Indoor unit C1 is in cooling operation mode, indoor unit C2
It is assumed that the indoor unit C3 is in the cooling operation mode, the indoor unit C3 is in the heating operation mode, and the indoor unit C4 is stopped. and,
Assume that the total required cooling capacity is greater than the total required heating capacity.

In this case, the main cooling operation mode is determined and the outdoor unit
Opens the two-way valve 9 (displayed in white) and closes the two-way valve 14 (displayed in black), thereby connecting the outdoor heat exchanger 10 to the discharge pipe 4.
Connect to a.

In branch unit B, PMV21, 31.41 is opened and PMV51 is closed (white display), and three-way valve 25 is opened.
, 35, 46 open (white display), and two-way valve 45, 5
5, 26, 36, and 56 (displayed in black), connect the gas pipe of the indoor unit C11C2 in the cooling operation mode to the low pressure side gas pipe S (intake pipe 5a), and connect the gas pipe of the indoor unit C3 in the heating operation mode. Connect to the high pressure side gas pipe G (discharge pipe 4b).

The refrigerant discharged from the compressor 1.2 thus enters the outdoor heat exchanger 10 through the two-way valve 9.

In this outdoor heat exchanger 10, the refrigerant condenses. The refrigerant that has passed through the outdoor heat exchanger 10 passes through the check valve 12 and liquid tank 13, and then passes through the PMV 21° 31 and the expansion valve 22.
．． 32 and enters the indoor units CI and C2. In this indoor unit C1+C2, the refrigerant is vaporized. The refrigerant that has passed through the indoor uni-soto C1°C2 passes through the three-way valve 25, 35 and the low-pressure side gas pipe S, and is sucked into the compressors 1 and 2.

At the same time, a part of the refrigerant discharged from the compressor 1.2 passes through the high pressure side gas pipe G and the two-way valve 46 to the indoor unit C.
Enter 3. In this indoor unit C3, the refrigerant condenses. The refrigerant that has passed through the indoor unit C3 passes through the check valve 43 and P
Pass through MV41, indoors: L chive) C1, C2 (PMV2
1.31) joins the refrigerant flow to

That is, the outdoor heat exchanger 10 is a condenser, and the indoor heat exchanger 2 is a condenser.
4.34 evaporator, indoor heat exchanger 44 works as a condenser.

In this case, part of the heat absorbed by the cooling-side indoor units CI and C2 is used as heat radiation from the heating-side indoor unit C3.

The number of operating compressors 1 and 2 and the operating frequency (output frequency of the inverter circuits 71 and 72) are determined according to the total required cooling capacity.

Here, outdoor unit A is indoor unit c1°C2,C
3. If the position is higher than C4, the refrigerant pressure in the liquid pipe W and the high pressure side gas pipe G in the cooling main operation mode described above.
Although the refrigerant pressure in the indoor unit c1. is the same at the position where it exits the outdoor unit A, ．． When viewed at positions C2, c3', and C4, the refrigerant pressure in the liquid pipe W is higher than the pressure of the refrigerant passing through the high-pressure side gas pipe G by the head difference.

In this case, a necessary amount of refrigerant flows into the cooling-side indoor units C, , C2, but it becomes difficult for the refrigerant to flow into the heating-side indoor unit C3. Therefore, although sufficient cooling capacity can be ensured, a situation arises in which heating capacity is only about 115 of the cooling capacity.

Therefore, the control shown in FIG. 6 is executed.

At the start of cooling main operation mode, PMV of outdoor unit A
16 to a predetermined initial opening degree. Furthermore, PMV21 corresponding to the cooling side indoor unit CI r 02,
31 to a predetermined initial opening degree, and fully open the PMV 41 corresponding to the heating indoor unit C3.

In this case, the initial opening degree of the PMVs 21 and 31 on the cooling side is a little narrow.

After the start of operation, 1 fixed time t1 during which the degree of superheating of the refrigerant becomes stable
has passed, the temperature of the refrigerant entering the indoor unit C1 on the cooling side is detected by the temperature sensor 101, and the temperature of the refrigerant entering the indoor unit C1 on the cooling side is detected.
The temperature of the refrigerant flowing out from the indoor unit C3 is detected by the temperature sensor 105, and the difference between the two detected temperatures is determined as the refrigerant superheat degree S in the indoor unit C3.
Detected as H. At the same time, the indoor unit C2 on the cooling side
The temperature of the refrigerant entering the indoor unit C2 is detected by the temperature sensor 102, and the temperature of the refrigerant flowing out from the indoor unit C2 is detected by the temperature sensor 1.
06, and the difference between the two detected temperatures is detected as the refrigerant superheat degree SH in the indoor unit C2.

If the refrigerant superheat degree SH in the indoor unit C1 is not within the fixed value SHs, the opening degree of the PMV 21 is increased by a predetermined value (several pulses). If the refrigerant superheat degree SH in the indoor unit C2 is not within the fixed value SHs, the opening degree of the PMV 31 is increased by a predetermined value (several pulses).

When the opening degree of PMV21, 31 increases, indoor unit C1
, C2 increases, and each refrigerant superheat degree SH changes in a decreasing direction.

Once either PMV21 or 31 is fully opened, it is time to open the PMV corresponding to indoor unit C3 on the heating side.
41 is reduced by a predetermined value (several pulses).

When the opening degree of PMV41 decreases, PMV21.3 increases accordingly.
The amount of refrigerant flowing to the 1 side, that is, the indoor units C, C2 side increases, and each refrigerant superheat degree SH changes in a decreasing direction.

Once the opening of PMV 41 has decreased to a certain set value, the reduction is terminated because further reduction will impede the heating capacity of indoor unit C3, and this time the opening of PMV 16 of outdoor unit A is reduced. Increase by a predetermined value (several pulses).

When the opening degree of the PMV 16 increases, the amount of refrigerant flowing through the liquid pipe W increases, and therefore the amount of refrigerant flowing into the indoor units C, C2 increases, and the degree of refrigerant superheating changes in a decreasing direction.

After the predetermined time t2, the refrigerant superheat degree SH is detected again, and the same control is repeated until the refrigerant superheat degree SH falls within the above-described certain range.

In this way, even if the outdoor unit A is located at a higher position than the indoor units c, C2, C3, and C4 as shown in FIG. The refrigerant can be distributed and supplied to the cooling-side indoor units C1 and C2 and the heating-side indoor unit C3 in a well-balanced manner.

Therefore, it is possible to ensure necessary and sufficient capacity in each of the cooling-side indoor units C1 and C2 and the heating-side indoor unit C3.

In each of the above embodiments, the case where there are four indoor units has been described as an example, but the number is not limited.

Moreover, although the case where the number of compressors is two has been described as an example, there is no limitation on the number of compressors, and it can be set as appropriate depending on the number of indoor units and the like.

[Effects of the Invention] As described above, according to the present invention, the air conditioner of claim 1 comprises one outdoor unit having a compressor and an outdoor heat exchanger, and a plurality of outdoor units each having an indoor heat exchanger. It consists of a single indoor unit, and a branch unit that communicates with the outdoor unit via a liquid pipe, a high-pressure side gas pipe, and a low-pressure side gas pipe, and switches the flow direction of refrigerant to each of the indoor units. In a multi-system air conditioner that enables simultaneous cooling and heating operation in each indoor unit by selecting the flow direction of the refrigerant, means for detecting the pressure of the refrigerant passing through the liquid pipe;
means for detecting the pressure of the refrigerant passing through the high pressure side gas pipe;
Since the device is equipped with a means for controlling the amount of refrigerant passing through the liquid pipe so that the difference between these detected pressures is within a certain range, even if the outdoor unit is located higher than the indoor unit, the indoor unit on the cooling side and the indoor unit on the heating side It is possible to ensure necessary and sufficient capacity in each indoor unit.

An air conditioner according to a second aspect of the present invention includes one outdoor unit having a compressor and an outdoor heat exchanger, a plurality of indoor units each having an indoor heat exchanger, and a liquid pipe and a high-pressure gas side connected to the outdoor unit. The branch unit communicates with the pipe and the low-pressure side gas pipe to switch the flow direction of the refrigerant to each indoor unit, and by selecting the flow direction of the refrigerant to each indoor unit, cooling and heating can be performed in each indoor unit. In a multi-system air conditioner that enables simultaneous operation of , and means for controlling at least one of the amounts of refrigerant flowing into the liquid pipe so that the detection result falls within a certain range, so that even if the outdoor unit is located higher than the indoor unit, cooling can be achieved. Necessary and sufficient capacity can be ensured in each of the side indoor unit and the heating side indoor unit.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a refrigeration cycle according to a first embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of a control circuit of the same embodiment.
FIG. 3 is a flowchart for explaining the operation of the second embodiment, FIG. 4 is a diagram showing the configuration of a refrigeration cycle according to the second embodiment of the present invention, and FIG. 5 is a diagram showing the configuration of the control circuit of the second embodiment. 6 are flowcharts for explaining the operation of the same embodiment, FIGS. 7 and 8 are diagrams showing the configuration of the refrigeration cycle of a conventional air conditioner, respectively, and FIG. 9 is an outdoor unit and a branch unit. , and the installation of each indoor unit are diagrams showing examples. 1.2...Variable capacity compressor, 10...Outdoor heat exchanger, 16-PMV, 24, 34, 44.54-1 Internal heat exchanger, 61.62...Pressure sensor, 101-108・・・
・Temperature sensor, A...Outdoor unit, B...Branch unit, C1+ C2, c3+ C4...Indoor unit, W...Liquid pipe, G...High pressure side gas pipe, S...
・Low pressure side gas pipe. Applicant's Representative Patent Attorney Takehiko Suzue

Claims (2)

[Claims] (1) One outdoor unit with a compressor and an outdoor heat exchanger, multiple indoor units each with an indoor heat exchanger, and a liquid pipe, a high-pressure side gas pipe, and a low-pressure side gas pipe in the outdoor unit. and a branch unit that communicates with each other through a branch unit and switches the flow direction of the refrigerant to each indoor unit, and by selecting the flow direction of the refrigerant to each indoor unit, it is possible to operate cooling and heating simultaneously in each indoor unit. In a multi-system air conditioner, there is provided a means for detecting the pressure of the refrigerant passing through the liquid pipe, a means for detecting the pressure of the refrigerant passing through the high-pressure side gas pipe, and a difference between these detected pressures within a certain range. An air conditioner comprising: means for controlling the amount of refrigerant passing through the liquid pipe so that the amount of refrigerant passes through the liquid pipe. (2) One outdoor unit with a compressor and an outdoor heat exchanger, multiple indoor units each with an indoor heat exchanger, and a liquid pipe, a high-pressure side gas pipe, and a low-pressure side gas pipe in the outdoor unit. and a branch unit that communicates with each other through a branch unit and switches the flow direction of the refrigerant to each indoor unit, and by selecting the flow direction of the refrigerant to each indoor unit, it is possible to operate cooling and heating simultaneously in each indoor unit. In a multi-system air conditioner, a means for detecting the degree of superheating of the refrigerant in the cooling-side indoor unit, an amount of refrigerant flowing into the cooling-side indoor unit, an amount of refrigerant flowing into the heating-side indoor unit, and a means for detecting the degree of superheating of the refrigerant in the cooling-side indoor unit, and Of the amount of refrigerant flowing,
An air conditioner comprising: means for controlling at least one of the detection results so that the detection results fall within a certain range.