JP2001336858A - Air conditioning apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioning apparatus in which the so-called gas deficiency is prevented. SOLUTION: An air conditioning apparatus 30 is adapted such that an outdoor unit 1 equipped with a compressor 2 and an outdoor heat exchanger 3, and indoor units 5a, 5b, 5c equipped with indoor heat exchangers 6a, 6b, 6c are connected through an inter-unit piping 10, one end of the outdoor heat exchanger is optionally branched and connected with a discharge tube 7 and a suction tube 8 of the compressor, and the inter-unit piping includes a high pressure gas tube 11 connected with the discharge tube, a low pressure gas tube 12 connected with the suction tube, and a liquid tube 13 connected with the other end of the outdoor heat exchanger with one end of the indoor heat exchanger connected with the high pressure gas tube and the low pressure gas tube and with the other end connected with the liquid tube. In the air conditioning apparatus, a bypass means 100 is provided between the high pressure gas tube 11 and the liquid tube 13 for communicating the insides of both tubes following a pressure difference in both tubes, and control means 101 is provided for drawing an opening of an outdoor expansion valve 27 upon all indoor units 5 in cooling operation in order to lower the pressure in the liquid tube 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an outdoor unit and a plurality of indoor units, and enables a plurality of indoor units to simultaneously perform a cooling operation or a heating operation, or a mixture of the heating operation and the cooling operation. The present invention relates to an air conditioner that can be implemented.

[0002]

2. Description of the Related Art An air conditioner that enables a plurality of indoor units to simultaneously perform a cooling operation or a heating operation, or a mixture of the heating operation and the cooling operation can be performed.
For example, it is described in Japanese Patent Publication No. 2804527.

In such an air conditioner, an outdoor unit having a compressor and an outdoor heat exchanger and a plurality of indoor units having an indoor heat exchanger are connected by unit piping. And one end of the outdoor heat exchanger is
The refrigerant discharge pipe and the refrigerant suction pipe of the compressor are selectively branched and connected, and a unit-to-unit pipe has a high-pressure gas pipe connected to the refrigerant discharge pipe and a low-pressure gas pipe connected to the refrigerant suction pipe. And a liquid pipe connected to the other end of the outdoor heat exchange.

According to the above configuration, when the heating operation and the cooling operation are operated in a mixed manner, all the three refrigerant pipes of the high pressure gas pipe, the low pressure gas pipe and the liquid pipe are used, and only the cooling operation is executed. The high-pressure gas pipe is shut down, and two refrigerant pipes, a low-pressure gas pipe and a liquid pipe, are used. When only the heating operation is performed, the low-pressure gas pipe is stopped, and two refrigerant pipes of the high-pressure gas pipe and the liquid pipe are used.

[0005]

However, in the conventional configuration, when only the cooling operation is performed, the high-pressure gas pipe is stopped, and the refrigerant flows from the outdoor unit to the indoor unit through the high-pressure gas pipe. However, there is a problem in that the refrigerant stagnates in the high-pressure gas pipe, and the amount of the refrigerant in the system is insufficient by that amount, resulting in a lack of gas.

In order to solve this problem, it has been proposed to provide a bypass means between the high-pressure gas pipe and the liquid pipe for communicating between the two pipes according to the pressure difference between the two pipes.

However, in the above proposal, when the pressure difference between the two pipes is small, that is, when the pressure in the liquid pipe becomes higher than a predetermined pressure, the refrigerant does not flow from the high-pressure gas pipe to the liquid pipe through the bypass means. There is.

An object of the present invention is to provide an air conditioner that solves the above-mentioned problems of the prior art and that prevents a so-called gas shortage.

[0009]

According to the first aspect of the present invention,
An outdoor unit including a compressor, an outdoor heat exchanger, and an outdoor expansion valve, and a plurality of indoor units including an indoor heat exchanger are connected by inter-unit piping, and one end of the outdoor heat exchanger is connected to a compressor. The refrigerant discharge pipe and the refrigerant suction pipe are alternately branched and connected, and the inter-unit piping is a high-pressure gas pipe connected to the refrigerant discharge pipe, and a low-pressure gas pipe connected to the refrigerant suction pipe. A liquid pipe connected to the other end of the outdoor heat exchanger, one end of the indoor heat exchanger is connected to the high-pressure gas pipe and the low-pressure gas pipe, and the other end is connected to the liquid pipe. In an air conditioner configured so that a plurality of the indoor units can simultaneously perform a cooling operation or a heating operation, or the cooling operation and the heating operation can be performed in a mixed manner, the high-pressure gas pipe and the liquid Pressure between both pipes Bypass means for communicating both pipes according to the difference is provided, and control means for reducing the opening degree of the outdoor expansion valve is provided in order to reduce the pressure in the liquid pipe when all the indoor units are in the cooling operation. Is what you do.

According to a second aspect of the present invention, in the first aspect, when the outdoor heat exchanger is a water-cooled type and the compressor is a variable capacity type, the control means increases when the water temperature is high. The more the compressor operates at a lower load, the more the control for reducing the opening degree of the outdoor expansion valve is executed.

[0011] The invention according to claim 3 is the invention according to claim 1 or 2.
In the above description, the bypass means is a capillary tube.

In the present invention, when only the cooling operation is performed, the pressure difference between the high-pressure gas pipe and the liquid pipe is increased by the control means, so that the refrigerant flows from the high-pressure gas pipe into the liquid pipe through the bypass means. However, this prevents the refrigerant from stagnating in the high-pressure gas pipe, so that the amount of the refrigerant in the system does not run short by that much, and the occurrence of gas shortage is suppressed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a refrigerant circuit diagram showing a first embodiment of an air conditioner according to the present invention. The air conditioner 30 includes an outdoor unit 1 including a compressor 2, a water-cooled outdoor heat exchanger 3, and an outdoor expansion valve 27;
a and an indoor unit 5a having an indoor expansion valve 18a;
An indoor unit 5b having an indoor heat exchanger 6b and an indoor expansion valve 18b, an indoor heat exchanger 6c and an indoor expansion valve 18c
And an indoor unit 5c having the same.

The outdoor unit 1 and the indoor units 5a, 5b, 5c are connected by the unit-to-unit piping 10, and the air conditioner 30 comprises the indoor unit 5a,
5b and 5c can be simultaneously operated for cooling operation or heating operation, or can be performed in combination with the cooling operation and heating operation.

In the outdoor unit 1, the outdoor heat exchanger 3
Is selectively branched and connected to a discharge pipe 7 and a suction pipe 8 of the compressor 2 via switching valves 9a and 9b, respectively. Further, the accumulator 4 is provided in the suction pipe 8.

The unit-to-unit pipe 10 is a high-pressure gas pipe 1
1, a low-pressure gas pipe 12 and a liquid pipe 13 are provided. The high-pressure gas pipe 11 is connected to the discharge pipe 7, and the low-pressure gas pipe 12 is connected to the suction pipe 8. The liquid pipe 13 is connected to the other end of the outdoor heat exchanger 3 via the outdoor expansion valve 27.

The other end of each of the indoor heat exchangers 6a, 6b, 6c of the indoor units 5a, 5b, 5c is provided with a liquid branch pipe 19a having an indoor expansion valve 18a and an indoor expansion valve 18b. Installed liquid branch pipe 19b, indoor expansion valve 1
8c is connected to the liquid pipe 13 via a liquid branch pipe 19c provided with the same.

One end of the indoor heat exchanger 6a of the indoor unit 5a is connected to the high-pressure gas pipe 11 via the gas branch pipe 14a, and is connected to the low-pressure gas pipe 12 via the gas branch pipe 15a. Connected. One end of the indoor heat exchanger 6b of the indoor unit 5b is connected to the gas branch pipe 1
4b, it is connected to the high pressure gas pipe 11 and is connected to the low pressure gas pipe 12 via the gas branch pipe 15b.
Further, one end of the indoor heat exchanger 6c of the indoor unit 5c is connected to the high-pressure gas pipe 11 via the gas branch pipe 14c and connected to the low-pressure gas pipe 12 via the gas branch pipe 15c. . Gas branch pipes 14a, 14b, 1
4c, the first on-off valves 16a, 16b, 16c
Is arranged. Further, the gas branch pipes 15a, 15b, 15
The second opening / closing valves 17a, 17b, 17c are provided for each of c.

A second on-off valve 17a is provided in the gas branch pipe 15a.
And the first bypass pipe 21a and the second bypass valve 24a are connected in parallel. In the gas branch pipe 15b,
Bypassing the second on-off valve 17b, the first bypass pipe 21
b and the second bypass valve 24b are connected in parallel. Further, a first bypass pipe 21c and a second bypass valve 24c are connected in parallel to the gas branch pipe 15c, bypassing the second on-off valve 17c.

Each of the first bypass pipes 21a, 21b and 21c has a third on-off valve 22a and a capillary tube 23a, respectively, and a third on-off valve 22b and a capillary tube 2a.
3b is the third on-off valve 22c and the capillary tube 23
c are respectively provided. In addition, the second bypass pipe 24
The fourth on-off valve 25a and the orifice 26a, the fourth on-off valve 25b and the orifice 26b, and the fourth on-off valve 25c and the orifice 26c are respectively disposed in each of a, 24b and 24c. Incidentally, reference numerals 20a and 20 in FIG.
b and 20c are solenoid valve kits.

In this embodiment, between the gas branch pipes 14a, 14b and 14c connected to the high-pressure gas pipe 11 and the liquid branch pipes 19a, 19b and 19c connected to the liquid pipe 13,
Bypass means (capillary tubes) 100a, 100b, 10 for communicating between the two pipes according to the pressure difference between the two pipes
0c is connected.

These capillary tubes 100a, 100a
00b and 100c are solenoid valve kits 20a, 20b, 2
0c.

A control means (controller) 101 is connected to the outdoor expansion valve 27.
1 executes control for reducing the opening degree of the outdoor expansion valve 27 in order to reduce the pressure in the liquid branch pipes 19a, 19b, 19c when the indoor units 5a, 5b, 5c are all in the cooling operation.

FIG. 2 shows the control contents of the control means 101.

Assuming that the outdoor heat exchanger 3 is a water-cooled type and the compressor 2 is a variable capacity type, the higher the water temperature of the water-cooled type, the higher the pressure and the higher the liquid branch pipe 19a. As the refrigerant of 19b and 19c is easily condensed and the compressor 2 is operated at a low load, that is, the output is controlled to be smaller, the pressure loss in the liquid branch pipes 19a, 19b and 19c becomes smaller, and the gas branch pipe becomes smaller. 14a, 14b, 14
The pressure difference from the refrigerant pressure in c becomes smaller.

Therefore, as shown in FIG. 2, the control means 101 controls the opening degree of the outdoor expansion valve 27 to be reduced as the water temperature is higher and the compressor 2 is operated at a lower load. Execute. Specifically, when the outdoor expansion valve 27 is driven by a pulse motor, for example, when the valve is fully opened at 480 pulses, the valve opening is narrowed to about 200 or 150 pulses.

Next, the driving operation will be described.

(A) When cooling all the indoor units 5a, 5b and 5c at the same time, the high-pressure gas pipe 11 is in a rest state.

In this case, one of the switching valves 9a of the outdoor heat exchanger 3 is opened and the other switching valve 9b is closed, and the first on-off valves 16a, 16a of the solenoid valve kits 20a, 20b, 20c are opened.
16b and 16c are closed, and the second on-off valve 17a,
17b, 17c, the third on-off valves 22a, 22b, 22c and the fourth on-off valves 25a, 25b, 25c are opened. Thereby, the refrigerant discharged from the compressor 2 flows sequentially to the discharge pipe 7, the switching valve 9a, and the outdoor heat exchanger 3, and after being condensed and liquefied by the outdoor heat exchanger 3, the liquid pipe 13 and the liquid branch pipe 19a, 19
After being distributed to the indoor expansion valves 18a, 18b, 18c of the respective room units 5a, 5b, 5c via b, 19c, the pressure is reduced here. Thereafter, the refrigerant is supplied to each of the indoor heat exchangers 6a, 6
b and 6c, the second on-off valve 17
a, 17b, 17c and third on-off valves 22a, 22b, 22
c and the fourth on-off valves 25a, 25b, 25c flow in parallel, and then are sucked into the compressor 2 through the low-pressure gas pipe 12, the suction pipe 8, and the accumulator 4 sequentially. Thus, all the indoor units 5a, 5b, 5c are simultaneously cooled by the indoor heat exchangers 6a, 6b, 6c acting as evaporators.

(B) When heating all the indoor units 5a, 5b, and 5c at the same time, the low-pressure gas pipe 12 is in a rest state.

In this case, one switching valve 9a of the outdoor heat exchanger 3 is closed and the other switching valve 9b is opened, and the first on-off valve 16 of the solenoid valve kits 20a, 20b, 20c is opened.
a, 16b, 16c, and the second on-off valve 17
a, 17b, 17c and third on-off valves 22a, 22b, 22
c and the fourth on-off valves 25a, 25b, 25c are closed. As a result, the refrigerant discharged from the compressor 2 is discharged from the discharge pipe 7,
Gas branch pipes 14a, 14b, sequentially passing through the high-pressure gas pipe 11,
14c, the first on-off valves 16a, 16b, 1
6c, flow to the indoor heat exchangers 6a, 6b, 6c, where they are condensed and liquefied, respectively, and then each indoor expansion valve 18a, 18
b, 18c, and the liquid branch pipes 19a, 19b, 19
The liquid is merged in the liquid tube 13 after passing through c. Thereafter, after being evaporated and vaporized in the outdoor heat exchanger 3, the refrigerant is sucked into the compressor 2 through the switching valve 9b, the suction pipe 8, and the accumulator 4 in order. Thus, each indoor heat exchanger 6a, 6b, 6 acting as a condenser
At c, all the indoor units 5a, 5b, 5c are heated simultaneously.

(C) At the same time, for example, when cooling the indoor units 5a and 5c and heating the indoor unit 5b,
All refrigerant tubes 11, 12, 13 are used.

In this case, one switching valve 9a of the outdoor heat exchanger 3 is opened and the other switching valve 9b is closed, and the electromagnetic valve kits 20a of the indoor units 5a and 5c for cooling are provided.
20c, the first on-off valves 16a, 16c are closed, and the second on-off valves 17a, 17c and the third on-off valve 22a,
22c and the fourth on-off valve 25a, 25c, and the first in the solenoid valve kit 20b of the indoor unit 5b for heating.
The on-off valve 16b is opened, and the second on-off valve 17b and the third
The on-off valve 22b and the fourth on-off valve 25b are closed. Then, a part of the refrigerant discharged from the compressor 2 is discharged to the discharge pipe 7 and the switching valve 9.
a, and the remaining refrigerant flows through the high-pressure gas pipe 11 for heating while flowing to the outdoor heat exchanger 3.
Flows to the first on-off valve 16b and the indoor heat exchanger 6b in the electromagnetic valve kit 20b, and is condensed and liquefied in the outdoor heat exchanger 3 of the indoor heat exchanger 6b.

The refrigerant condensed and liquefied in the heat exchanger 6b and the outdoor heat exchanger 3 is depressurized by the indoor expansion valves 18a and 18c of the indoor units 5a and 5c via the liquid pipe 13, and then is depressurized. It is evaporated and vaporized in the heat exchangers 6a and 6c. Thereafter, the refrigerant is supplied to the second on-off valves 17a, 17c, the third on-off valves 22a, 22b, 22c, and the fourth on-off valve 25.
a, 25b, and 25c flow together and are merged by the low-pressure gas pipe 12, and are sucked into the compressor 2 through the suction pipe 8 and the accumulator 4 in order. As described above, the indoor unit 5b is heated by the indoor heat exchanger 6b acting as a condenser, and the indoor units 5a and 5c are cooled by the other indoor heat exchangers 6a and 6c acting as evaporators.

Next, for example, when cooling is performed by the indoor unit 5b and heating is performed by the indoor units 5a and 5c, one switching valve 9a of the outdoor heat exchanger 3 is closed and the other switching valve 9b is opened. The indoor unit 5a that closes the first opening / closing valve 16b in the electromagnetic valve kit 20b of the indoor unit 5b to be cooled, opens the second opening / closing valve 17b, the third opening / closing valve 22b, and the fourth opening / closing valve 25b, and heats;
5c, the first on-off valves 16a and 16c in the solenoid valve kits 20a and 20c are opened, and the second on-off valves 17a and 17c are opened.
7c, the third on-off valve 22a, 22c and the fourth on-off valve 25a,
25c is closed. Then, the refrigerant discharged from the compressor 2 passes through the discharge pipe 7 and the high-pressure gas pipe 11 sequentially, and the first on-off valve 1
6a and 16c, and each indoor heat exchanger 6
It is condensed and liquefied at a and 6c. The liquefied refrigerant flows into the liquid pipe 13 via the indoor expansion valves 18a and 18c which are fully opened. Some of the liquid refrigerant in this liquid pipe is
After the pressure is reduced by the indoor expansion valve 18b, the indoor heat exchanger 6b
After the remaining liquid refrigerant is decompressed by the outdoor expansion valve 27, it is evaporated and vaporized in the outdoor heat exchanger 3, and is sucked into the compressor 2 through the suction pipe 8 and the accumulator 4 in order. Thus, the indoor heat exchanger 6 acting as a condenser
a, 6c heats the indoor units 5a, 5c, and the other indoor heat exchanger 6b, which acts as an evaporator, heats the indoor units 5a, 5c.
b is cooled.

As described above, the indoor unit 5a for cooling is
Indoor unit 5 heated by the number (cooling capacity) of 5b, 5c
When the number is larger than the number (heating capacity) of the indoor units 5a, 5b, and 5c, the number of the indoor units 5a, 5b, and 5c to be cooled (heating capacity) is increased. When the number is smaller than the number (cooling capacity) of the indoor units 5a, 5b, and 5c, the outdoor heat exchanger 3 functions as an evaporator, whereby any of the indoor units 5a, 5b, and 5c can be freely cooled and heated.

(D) In this embodiment, when the state of the above item (A), that is, when all the indoor units 5a, 5b, and 5c are cooled at the same time, the refrigerant is prevented from falling into the high-pressure gas pipe 11 in the halt state. Measures are taken.

When only the heating operation is performed as described above, the high-pressure gas pipe 11 is stopped, so that the refrigerant flows out of the outdoor unit 1 to the indoor unit 5 through the high-pressure gas pipe 11, and There is a risk of falling asleep in the tube 11.

In order to prevent this, in the present embodiment, as described above, the gas branch pipes 14a, 14b, 14c connected to the high-pressure gas pipe 11 and the liquid branch pipes 19a, 19b connected to the liquid pipe 13 , 19c are connected to the capillary tubes 100a, 100b, 100c. Therefore, the refrigerant liquefied in the high-pressure gas pipe 11 and the gas branch pipes 14a, 14b, and 14c flows into the liquid branch pipes 19a, 19b, and 19c via the capillary tube 100. Of the liquid refrigerant can be prevented.

In this embodiment, when the state of the above item (A) is reached, the controller 101 sets the outdoor expansion valve 27
Aperture.

As a result, the refrigerant pressure in the liquid branch pipes 19a to 19c decreases, and the pressure difference between the refrigerant pressure and the refrigerant pressure in the gas branch pipes 14a to 14c increases.
The refrigerant liquefied in the gas branch pipes 14a to 14c easily flows into the liquid branch pipes 19a to 19c.
The stagnation of the liquid refrigerant into the high-pressure gas pipe 11 can be almost completely prevented.

The capillary tube 100 is stored in the solenoid valve kits 20a to 20c to simplify the piping.

The capillary tube 100 need not be stored in all the solenoid valve kits 20a to 20c, but may be stored only in the solenoid valve kit 20a of the indoor unit closest to the outdoor unit, for example.

Further, as shown in FIG.
If the water temperature is higher and the compressor 2 is operated with a lower load, the opening degree of the outdoor expansion valve 27 is controlled to be greatly reduced. The liquid refrigerant can be prevented from stagnation.

Although the present invention has been described based on the above embodiment, the present invention is not limited to this.

For example, the bypass means is not limited to the capillary tube, but may be a control valve which is opened only during the cooling only operation.

[0048]

As described above, according to the present invention, in the cooling only operation, the control means reduces the opening degree of the outdoor expansion valve, so that the refrigerant pressure in the liquid pipe decreases, and the refrigerant pressure and the high pressure gas pipe Therefore, the refrigerant liquefied in the high-pressure gas pipe easily flows into the liquid pipe, and the stagnation of the liquid refrigerant into the high-pressure gas pipe can be prevented. Therefore, the occurrence of a gas shortage in the system is prevented.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram showing a first embodiment of an air conditioner according to the present invention.

FIG. 2 is a diagram showing control contents of a control means.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outdoor unit 2 Compressor 3 Outdoor heat exchanger 5a, 5b, 5c Indoor unit 6a, 6b, 6c Indoor heat exchanger 7 Discharge pipe 8 Suction pipe 10 Unit piping 11 High pressure gas pipe 12 Low pressure gas pipe 13 Liquid pipe 16a 16b, 16c First open / close valve 18a, 18b, 18c Indoor expansion valve 30 Air conditioner 100 Bypass means (capillary tube) 101 Control means

Claims (3)

[Claims] An outdoor unit having a compressor, an outdoor heat exchanger and an outdoor expansion valve, and a plurality of indoor units having an indoor heat exchanger are connected by interunit piping. One end is selectively branched and connected to a refrigerant discharge pipe and a refrigerant suction pipe of the compressor, and the inter-unit pipe is connected to the high-pressure gas pipe connected to the refrigerant discharge pipe and the refrigerant suction pipe. A low-pressure gas pipe, and a liquid pipe connected to the other end of the outdoor heat exchanger. One end of the indoor heat exchanger is connected to the high-pressure gas pipe and the low-pressure gas pipe, and the other end is connected to the liquid pipe. An air conditioner connected to each of the pipes and capable of simultaneously performing the cooling operation or the heating operation of the plurality of indoor units, or configured to enable the cooling operation and the heating operation to be performed in a mixed manner. Between the gas pipe and the liquid pipe A bypass means for communicating between the two pipes according to the pressure difference between the two pipes, and a control means for reducing the opening degree of the outdoor expansion valve in order to reduce the pressure in the liquid pipe when all the indoor units are in a cooling operation. An air conditioner, characterized in that: 2. In a case where the outdoor heat exchanger is a water-cooled type and the compressor is a variable capacity type, the control means is configured such that the higher the water temperature and the lower the load operation of the compressor, the higher the water temperature. 2. The air conditioner according to claim 1, wherein control for reducing an opening degree of the outdoor expansion valve is executed. 3. The air conditioner according to claim 1, wherein said bypass means is a capillary tube.