JPH10300254A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner of a multi-room type which prevents the discharge pressure of a compressor from lowering too much even when a cooling operation is conducted in a state of an outdoor temperature being low, without increasing a working amount of refrigerant. SOLUTION: A first pressure and a second pressure higher than this and/or a first temperature and a second temperature higher than this are set in a control device 33 connected to a pressure sensor 31 and/or a temperature sensor 32. At the time of a cooling operation, a four-wag valve 6 to which a check valve 22 is connected is put in a heating operation when the discharge pressure of a compressor 5 becomes the first set pressure or below and/or when an outdoor temperature becomes the first set temperature or below, while the four-way valve 6 is put in the cooling operation when the discharge pressure of the compressor 5 becomes the second set pressure or above and/or when the outdoor temperature becomes the second set temperature or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-chamber air conditioner in which the discharge pressure of a compressor is not excessively reduced even during a cooling operation in a state where the outdoor temperature is low.

[0002]

2. Description of the Related Art As a refrigerating cycle having a plurality of four-way valves, for example, a refrigerating cycle disclosed in Japanese Patent Application Laid-Open No. 3-75459 has been proposed. In this refrigeration cycle, in the cooling operation, all of the plurality of four-way valves are set to the cooling mode,
When the outdoor temperature is low, the outdoor expansion valve connected to the outdoor heat exchanger is throttled to store the liquid refrigerant in the outdoor heat exchanger, and the heat transfer area is reduced so that the discharge pressure does not decrease.

[0003]

That is, in the above-mentioned apparatus, since the liquid refrigerant is stored in one of the heat exchangers of the outdoor unit to prevent a decrease in the discharge pressure of the compressor, the apparatus is used. The amount of refrigerant used increases and the cost increases. Also, should the piping system break and the refrigerant flows out,
Greater impact on the environment.

[0004] In view of the above circumstances, an object of the present invention is to prevent the discharge pressure of the compressor from excessively decreasing even during cooling operation in a state where the outdoor temperature is low without increasing the amount of refrigerant used. To provide a multi-room air conditioner.

[0005]

In order to achieve the above object, according to a first aspect of the present invention, a compressor is connected to a pipe branched from a discharge side of the compressor via a four-way valve. A plurality of heat exchangers, a plurality of expansion valves capable of adjusting the flow rate connected to each heat exchanger, and a liquid tank connected to each expansion valve to store the liquid refrigerant by merging the flow of the refrigerant, In piping connected to at least one of the four-way valves,
A check valve that is closed during the heating operation and is always opened during the cooling operation, a suction pipe connecting each of the four-way valves and the suction side of the compressor, and a suction pipe between the four-way valve and the check valve. An outdoor unit having a small-diameter pipe connecting the liquid tank, a flow-adjustable expansion valve connected to the liquid tank and connected to a branched pipe, and connected between the expansion valve and the four-way valve. In an air conditioner including a plurality of indoor units including a heat exchanger, one or both of a pressure sensor for detecting a discharge pressure of the compressor or a temperature sensor for detecting an outside air temperature, and each indoor unit and Connected to one or both of the pressure sensor and the temperature sensor, based on one or both of the operating state of each indoor unit and the discharge pressure or outside temperature of the compressor It provided a control device for controlling the serial four-way valve.

Further, in the second invention of the present application, the control device is set with a first pressure and a second pressure higher than the first pressure, and the discharge pressure of the compressor is set to the first pressure during the cooling operation.
When the pressure becomes equal to or less than the set pressure, the four-way valve to which the check valve is connected is set to the heating operation, and when the pressure becomes equal to or more than the second set pressure, the four-way valve is set to the cooling operation.

[0007] In the third invention of the present application, the control device is set with a first temperature and a second temperature higher than the first temperature, and during the cooling operation, the outdoor temperature is set to the first set temperature. When the temperature becomes below, the four-way valve connected to the check valve is set to the heating operation, and when the temperature becomes equal to or higher than the second set temperature, the four-way valve is set to the cooling operation.

Further, in the fourth invention of the present application,
In the control device connected to the temperature sensor and the pressure sensor, a first temperature, a second temperature higher than this, a first pressure, and a second pressure higher than this are set, and during the cooling operation, When the outdoor temperature is equal to or lower than the first set temperature and the discharge pressure of the compressor becomes equal to or lower than the first set pressure, the four-way valve connected to the check valve is set to the heating operation, and the outdoor temperature is set to the second set temperature. As described above, the four-way valve is set to the cooling operation when the discharge pressure of the compressor becomes equal to or higher than the second set pressure.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a refrigeration cycle diagram of the air conditioner according to the present invention. 5, the same components as those in FIG. 5 are denoted by the same reference numerals.

An accumulator 21 is connected to a suction port of the compressor 5. A check valve 22 has one end connected to a gas pipe 26 connected to the indoor units 2, 3 and 4, and the other end connected to the C port of the four-way valve 6. A capillary 23 has one end connected between the check valve 22 and the C port of the four-way valve 6 and the other end connected to a suction pipe. Therefore, the check valve 22 and the capillary 23 are connected in parallel between the C port of the four-way valve 6 and the E port of the four-way valve 7 via the suction pipe.

A liquid tank 24 is connected to a liquid pipe 25 between the expansion valves 10, 11 and the indoor units 2, 3, 4. An outdoor fan 27 is arranged on the outlet side of the ventilation path of the heat exchangers 8 and 9. Reference numerals 28, 29, and 30 denote indoor fans, which are arranged in the indoor units 2, 3, and 4, respectively.

A pressure sensor 31 detects the discharge pressure of the compressor 5. A temperature sensor 32 detects the temperature of the outside air sucked into the heat exchangers 8 and 9. 33 is a control device,
The indoor units 2, 3, and 4 are connected to the pressure sensor 31 and the temperature sensor 32, and control the turning on and off of the power to the four-way valves 6 and 7 and the opening and closing of the expansion valve 10.

The four-way valve 6 is in a heating operation mode in which the suction pipe communicates with the heat exchanger 8 and the discharge pipe communicates with the gas pipe 26 when the power is off. The four-way valve 7 is in a cooling operation mode in which the discharge pipe and the heat exchanger 9 communicate with each other while the power supply is off, and the suction pipe and the gas pipe 26 communicate with each other.

FIGS. 2A and 2B are explanatory diagrams of the operation of the refrigeration cycle shown in FIG. 1, in which FIG. 2A shows a heating operation, FIG.
(C) shows the flow of the refrigerant during the cooling operation when the outdoor temperature is low.

First, during the heating operation, as shown in FIG. 2A, the four-way valve 7 is turned on to set the heating mode. On the other hand, the power of the four-way valve 6 is turned off, and the four-way valve 6 is set to the heating mode.

The high-temperature and high-pressure refrigerant discharged from the compressor 5 flows into the gas pipe 26 from the four-way valve 7 through the discharge pipe. At this time, a part of the refrigerant discharged from the compressor 5 is branched at the discharge pipe and flows into the suction pipe through the four-way valve 6 and the capillary 23.

The refrigerant is branched by the gas pipe 26 and flows into the heat exchangers 18, 19, 20 of the indoor units 2, 3, 4. Then, it is cooled by heat exchange with the indoor air blown to the heat exchangers 18, 19, 20 by the indoor fans 28, 29, 30 and condensed to become a liquid refrigerant. On the other hand, the room air heated by the heat exchange flows out again into the room to heat the room.

The liquid refrigerant condensed in the heat exchangers 18, 19, 20 passes through expansion valves 15, 16, 17, joins in a liquid pipe 25, and flows into a liquid tank 24. The liquid refrigerant in the liquid tank 24 is reduced in pressure by the expansion valves 10 and 11 to become a low-pressure liquid refrigerant, flows into the heat exchangers 8 and 9, exchanges heat with outdoor air blown by the outdoor fan 31, and evaporates. It becomes a low-pressure gas refrigerant.

The gas refrigerant vaporized in each of the heat exchangers 8 and 9 is:
After passing through the four-way valves 6 and 9 and merging at the suction pipe, it is sucked into the compressor 5 through the accumulator 21.

Next, during the cooling operation, as shown in FIG. 2B, the four-way valve 6 is turned on to set the cooling mode. On the other hand, the power of the four-way valve 7 is turned off, and the four-way valve 7 is set to the cooling mode.

The high-temperature and high-pressure refrigerant discharged from the compressor 5 flows into the heat exchangers 8 and 9 from the four-way valves 6 and 7 through discharge pipes. In the heat exchangers 8 and 9, the refrigerant is cooled by heat exchange with the outdoor air blown by the outdoor fan 31, condensed into a liquid refrigerant, passed through the expansion valves 10 and 11, and discharged into the liquid tank 24.
Flows into.

The liquid refrigerant in the liquid tank 24 passes through the liquid pipe 25 and is branched into each of the indoor units 2, 3, and 4. The expansion valves 15, 16, and 17 are decompressed, and the heat exchangers 18 and 1 are depressurized.
Flow into 9 and 20. And the indoor fans 28, 29,
The heat exchange with the indoor air sent to the heat exchangers 18, 19, and 20 by the heat exchanger 30 removes the heat of vaporization from the indoor air to become a gas refrigerant. On the other hand, the indoor air is cooled by being deprived of heat of vaporization by the refrigerant, flows into the room, and is cooled.

The gas refrigerant vaporized in the heat exchangers 18, 19 and 20 passes through a gas pipe 26, a part of which is from the four-way valve 7 and another part which is branched off by the gas pipe 26 is a check valve 22.
Flows through the four-way valve 6 through the capillary 23 into the suction pipe, and is sucked into the compressor 5 through the accumulator 21.

Next, during the cooling operation when the outdoor temperature is low, the power of the four-way valve 7 is turned off and the cooling mode is set, as shown in FIG. 2 (C). On the other hand, the power supply of the four-way valve 6 is turned off and the heating mode is set. Also,
The expansion valve 10 is fully closed.

The high-temperature and high-pressure refrigerant discharged from the compressor 5 flows into the heat exchanger 9 from the four-way valve 7 through the discharge pipe. At this time, a part of the refrigerant discharged from the compressor 5 is branched at the discharge pipe and flows into the suction pipe through the four-way valve 6 and the capillary 23.

The heat is exchanged with the outdoor air blown by the outdoor fan 31 in the heat exchanger 9 to be cooled and condensed into a liquid refrigerant, which flows into the liquid tank 24 through the expansion valve 11.

The liquid refrigerant in the liquid tank 24 passes through the liquid pipe 25 and branches into the indoor units 2, 3, and 4. The expansion valves 15, 16, and 17 are decompressed, and the heat exchangers 18, 1 and 2 are depressurized.
Flow into 9 and 20. And the indoor fans 28, 29,
The heat exchange with the indoor air sent to the heat exchangers 18, 19, and 20 by the heat exchanger 30 removes the heat of vaporization from the indoor air to become a gas refrigerant. On the other hand, the indoor air is cooled by being deprived of heat of vaporization by the refrigerant, flows into the room, and is cooled.

The gas refrigerant vaporized in the heat exchangers 18, 19, and 20 passes through a gas pipe 26, and a part of the gas refrigerant flows from the four-way valve 7 and another part branched from the gas pipe 26 serves as a check valve 22.
Flows through the four-way valve 6 through the capillary 23 into the suction pipe, and is sucked into the compressor 5 through the accumulator 21.

The switching between (B) and (C) in FIG.
This is performed by the control device 33 shown in FIG. For example, as shown in FIG. 3, the first pressure is 1 MPa, and the second pressure is 2 MPa.
When the outdoor temperature is low, the condensing capacity increases due to the low outdoor temperature, and when the discharge pressure of the compressor becomes lower than the first pressure 1 MPa, the mode of the four-way valve 6 is switched to heating, and the expansion valve is switched. 10 is fully closed. When the discharge pressure of the compressor rises and exceeds 1 MPa, the heating mode is maintained. When the discharge pressure exceeds the second pressure of 2 MPa, the mode of the four-way valve 6 is switched to cooling, and the expansion valve 1 is turned on.
Open 0 to a predetermined opening. When the discharge pressure of the compressor is between the first pressure and the second pressure, the previous state is maintained.

It should be noted that the discharge pressure of the compressor is not limited to the first and second pressures.
When the pressure exceeds the pressure, the mode of the four-way valve 6 is switched. However, the mode of the four-way valve 6 may be switched after a certain time has elapsed after each pressure is exceeded. Thus, by providing the differential at the switching timing of the four-way valve, the number of times of switching the four-way valve can be reduced, and the life of the four-way valve can be extended.

For example, as shown in FIG.
Is set to 5 ° C. and the second temperature is set to 15 ° C. When the outdoor temperature is equal to or lower than the first temperature 5 ° C., the mode of the four-way valve 6 is set to heating and the expansion valve 10 is fully closed. When the outdoor temperature is equal to or higher than the second temperature of 15 ° C., the mode of the four-way valve 6 is switched to cooling, and the expansion valve 10 is opened to a predetermined opening. When the outdoor temperature is between the first temperature and the second temperature, the previous state is maintained.

Further, the four-way valve switching control based on the discharge pressure of the compressor shown in FIGS. 3 and 4 is combined with the four-way valve switching control based on the outdoor temperature, for example, when the outdoor temperature is equal to or lower than the first temperature during the cooling operation, And, when the discharge pressure of the compressor is equal to or lower than the first pressure, or when the outdoor temperature is equal to or higher than the second temperature and the discharge pressure of the compressor is equal to or higher than the second pressure, the four-way valve is turned on. Switching may be performed.

The first and second pressures and the first and second temperatures may be appropriately set according to the installation conditions of the air conditioner. In the case where the discharge pressure of the compressor and the outdoor temperature are controlled in combination, third and fourth pressures and temperatures may be set.

[0034]

As described above, according to the present invention, during the cooling operation when the outdoor temperature is low, when the discharge pressure of the compressor drops, or when the outdoor temperature falls below the set temperature, Since the refrigerant is not allowed to flow through some of the heat exchangers, it is possible to reduce the condensation capacity of the refrigerant and prevent the discharge pressure from lowering.

In addition, compared to the case where a part of the heat exchanger of the outdoor unit is filled with the liquid refrigerant to prevent the discharge pressure from lowering, the amount of the refrigerant used can be reduced, and the refrigerant may leak into the atmosphere. Even so, the effect on the environment can be reduced. Further, the cost of the air conditioner can be reduced by reducing the amount of the refrigerant used.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a refrigeration cycle illustrating one embodiment of the present invention.

FIGS. 2A and 2B are operation explanatory diagrams showing the flow of the refrigerant in the refrigeration cycle shown in FIG. 1 during heating, and FIGS. 2B and 2C during cooling.

FIG. 3 is a characteristic diagram showing a switching timing of a four-way valve by a discharge pressure according to the present invention.

FIG. 4 is a characteristic diagram showing a switching timing of the four-way valve according to the outdoor temperature according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outdoor unit, 2, 3, 4 ... Indoor unit, 5 ... Compressor, 6, 7 ... Four-way valve, 8, 9 ... Heat exchanger, 10, 11
... expansion valves, 15, 16, 17 ... expansion valves, 18, 19, 2
0: heat exchanger 22: check valve, 23: capillary, 24: liquid tank, 3
1 ... pressure sensor, 32 ... temperature sensor, 33 ... control device.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yasutaka Yoshida 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Inside Air Conditioning Systems Division, Hitachi, Ltd. (72) Inventor Shinichiro Yamada 390 Muramatsu, Shimizu-shi, Shizuoka Air Conditioning System, Hitachi, Ltd. Within Business Unit (72) Inventor Kenichi Nakamura 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Inside Air Conditioning System Business Division, Hitachi, Ltd.

Claims (4)

[Claims] 1. A compressor, a plurality of heat exchangers connected to pipes branched from a discharge side of the compressor via four-way valves, respectively, and a plurality of flow rate-adjustable connected to each heat exchanger. The expansion valve, connected to each expansion valve, a liquid tank that stores the liquid refrigerant by merging the flow of the refrigerant, and a pipe connected to at least one of the four-way valve, closed during the heating operation, during the cooling operation A check valve that is always open, a suction pipe that connects each of the four-way valves and the suction side of the compressor, and a small-diameter pipe that connects the suction pipe between the four-way valve and the check valve. Outdoor unit, and a flow-adjustable expansion valve connected to each of the branched pipes connected to the liquid tank,
In an air conditioner including a plurality of indoor units including the expansion valve and a heat exchanger connected between the four-way valve, a pressure sensor for detecting a discharge pressure of the compressor or a temperature for detecting an outside air temperature. Any one or both of the sensors are connected to one or both of each indoor unit and the pressure sensor or the temperature sensor, and either one of the operating state of each of the indoor units and the discharge pressure or the outside air temperature of the compressor or An air conditioner comprising: a control device that controls the four-way valve based on both. 2. A first pressure and a second pressure higher than the first pressure are set in the control device connected to the pressure sensor, and a discharge pressure of the compressor is equal to or lower than a first set pressure during a cooling operation. The air conditioner according to claim 1, wherein the four-way valve to which the check valve is connected is set to a heating operation when the pressure becomes equal to, and the four-way valve is set to a cooling operation when the pressure becomes equal to or higher than a second set pressure. . 3. A first temperature and a second temperature higher than the first temperature are set in the control device connected to the temperature sensor, and the outdoor temperature becomes equal to or lower than the first set temperature during the cooling operation. The air conditioner according to claim 1, wherein the four-way valve to which the check valve is connected is set to a heating operation, and the temperature of the four-way valve is set to a cooling operation when the temperature exceeds a second set temperature. 4. A control device connected to a temperature sensor and a pressure sensor, wherein a first temperature, a second temperature higher than the first temperature, a first pressure, and a second pressure higher than this are set. During the cooling operation, when the outdoor temperature is equal to or lower than the first set temperature,
When the discharge pressure of the compressor becomes equal to or lower than the first set pressure, the four-way valve connected to the check valve is set to the heating operation, the outdoor temperature is equal to or higher than the second set temperature, and the discharge pressure of the compressor is set to the second set temperature. The air conditioner according to claim 1, wherein the four-way valve is set to a cooling operation when the pressure becomes equal to or higher than the set pressure.