JPH11304265A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner which does not cause lubricant deficiency in its compressor when defrosting is made during heating operation. SOLUTION: In an air conditioner provided with a heat pump type refrigerating cycle for circulating a refrigerant front the discharge opening of a compressor 1 to the suction opening of the compressor 1 through a four-way valve 4, an outdoor heat exchanger 5, an expanding mechanism 6, an indoor heat exchanger 7, and the four-way valve 4, an oil separator 2 equipped with an oil returning means which returns a lubricant to the suction side of the compressor 1 is provided on the discharge side of the compressor 1 and connected to the outdoor heat exchanger 5 and expanding means 6 through a bypass circuit 8 equipped with an open/close valve 9 and the opening and closing of the valve 9 is controlled in accordance with the operation mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner, and more particularly to a structure for returning lubricating oil to a compressor during a defrosting operation.

[0002]

2. Description of the Related Art As shown in FIG. 4, a conventional air conditioner has a compressor 1 for compressing a refrigerant vapor, and a compressor 4 for cooling operation, heating operation, and the like, which are discharged from the compressor 1. A four-way valve that switches in accordance with 5 is an outdoor heat exchanger that is installed outdoors and exchanges heat with the outside air, 6 is an electronic expansion valve that is an expansion mechanism through which the refrigerant passes and adiabatically expands, and 7 is installed indoors. An indoor heat exchanger 8 for exchanging heat of refrigerant with indoor air, 8 is a discharge side of the compressor 1 and an outdoor heat exchanger 7
And a bypass circuit including an on-off valve 9 for connecting between the electronic expansion valve 6 and the electronic expansion valve 6.

[0003]

However, in the above configuration, when the defrosting operation is started during the heating operation, the operating frequency of the compressor is reduced and the refrigerant circulation amount is reduced, so that the amount of lubricating oil returned to the compressor is reduced. And the lubricating oil becomes insufficient. In view of the above problems, an object of the present invention is to provide an air conditioner that does not cause a shortage of lubrication oil of a compressor during a defrosting operation during a heating operation.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a four-way valve, an outdoor heat exchanger, an expansion mechanism, an indoor heat exchanger, and a refrigerant discharged from a discharge port of a compressor. In an air conditioner having a heat pump refrigeration cycle circulating to a suction port of the compressor via a valve, an oil return means is provided on a discharge side of the compressor for returning lubricating oil to a suction side of the compressor. A configuration in which a separator is provided, and the oil separator, the outdoor heat exchanger, and the expansion mechanism are connected by a bypass circuit having an on-off valve, and the on-off valve is controlled to open and close according to an operation mode. It has become.

[0005] Further, the bypass circuit is connected to a lower end of the oil separator.

Further, the oil return means is constituted by an oil return pipe provided with a capillary tube connecting between a lower end of the oil separator and a suction side of the compressor.

The on-off valve is controlled to be opened during the defrosting operation of the outdoor heat exchanger during the heating operation and closed during the normal heating operation and other operation modes.

Further, the expansion mechanism is configured as an electronic expansion valve.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the embodiments of the present invention shown in FIGS. 1
Is a compressor that compresses refrigerant vapor, and 2 is an oil separator that allows the refrigerant discharged from the compressor 1 to flow in, separates lubricating oil from the refrigerant, and returns the lubricating oil to the suction side of the compressor 1 by the capillary tube 3. 4 is a four-way valve for switching the flow of the refrigerant discharged from the compressor 1 in accordance with cooling operation, heating operation, etc., 5 is an outdoor heat exchanger which is installed outdoors and exchanges heat of the refrigerant with the outside air, 6 is An electronic expansion valve, which is an expansion mechanism through which the refrigerant passes and adiabatically expands, 7 is an indoor heat exchanger that is installed indoors and exchanges heat of the refrigerant with indoor air, 8 is a lower end of the oil separator 2 and Heat exchanger 7 and electronic expansion valve 6
This is a bypass circuit provided with an on-off valve 9 that connects between the two.

Next, the operation of the above configuration will be described. FIG. 3 shows the control contents of the on-off valve 9 in each operation state. First, the operation during the heating operation shown in FIG. 1 will be described. The high-temperature and high-pressure refrigerant vapor discharged from the compressor 1 flows into the oil separator 2, is separated by the oil separator 2, and the lubricating oil accumulated in a lower portion of the oil separator 2 is removed by the capillary tube. 3 and gradually returned to the suction side of the compressor 1, and the high-temperature and high-pressure refrigerant vapor flowing out of the oil separator 2 passes through the four-way valve 4 and passes through the indoor heat exchanger 5 to the indoor air. The refrigerant is condensed by heating and becomes a high-temperature and high-pressure refrigerant liquid. The high-temperature and high-pressure refrigerant liquid is adiabatically expanded by the electronic expansion valve 6 to become a low-temperature and low-pressure refrigerant liquid. Is evaporated by absorbing heat from the outside air in the outdoor heat exchanger 5 to become low-temperature and low-pressure refrigerant vapor, which passes through the four-way valve 4 and returns to the suction side of the compressor 1. At this time, since the surface of the outdoor heat exchanger 5 is cooler than the outside air, moisture in the outside air condenses or frosts on the surface of the outdoor heat exchanger 5, and the heat exchange capacity of the outdoor heat exchanger 5 is reduced. Therefore, the following defrosting operation is performed.

Next, the operation of the defrosting operation during the heating operation shown in FIG. 2 will be described. The basic flow of the refrigerant is the same as that in the normal heating operation described above. By opening the on-off valve 9, the lubricating oil accumulated in the lower part of the oil separator 2 is combined with the high-temperature and high-pressure refrigerant vapor by the pressure of the high-temperature and high-pressure refrigerant vapor discharged from the compressor 1. The air is returned between the outdoor heat exchanger 5 and the electronic expansion valve 6 through the bypass circuit 8 at a stretch, and the outdoor heat exchanger 5 is defrosted by the high-temperature and high-pressure refrigerant vapor. A large amount of lubricating oil that has passed through the exchanger 5 returns to the compressor 1. At the start of the defrosting operation during the heating operation, the operating frequency of the compressor 1 decreases, and the amount of normal lubricating oil returned from the oil separator 2 through the capillary tube 3 is insufficient, so By returning a large amount of lubricating oil through the bypass circuit 8 in a short time, shortage of lubricating oil in the compressor 1 can be prevented. Also, by connecting the bypass circuit 8 to the lower end of the oil separator 2, the lubricating oil accumulated in the lower part of the oil separator 2 can be reliably supplied to the compressor 1 during the defrosting operation during the heating operation. Can be returned to. In other operation modes such as a cooling operation other than the heating operation, the on-off valve 9 is in a closed state.

[0012]

As described above, according to the present invention,
An air conditioner that does not cause a shortage of lubricating oil for the compressor during the defrosting operation during the heating operation.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram showing one embodiment of an air conditioner according to the present invention, showing a normal heating operation state.

FIG. 2 is a refrigerant circuit diagram showing one embodiment of the air conditioner according to the present invention, showing a defrosting operation state during a heating operation.

FIG. 3 shows control contents of an on-off valve in each operation state of the air conditioner according to the embodiment of the present invention.

FIG. 4 is a refrigerant circuit diagram of a conventional air conditioner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Oil separator 3 Capillary tube 4 Four-way valve 5 Outdoor heat exchanger 6 Electronic expansion valve (expansion mechanism) 7 Indoor heat exchanger 8 Bypass circuit 9 On-off valve

Claims (5)

[Claims] 1. A refrigerant discharged from a discharge port of a compressor,
A four-way valve, an outdoor heat exchanger, an expansion mechanism, an indoor heat exchanger, an air conditioner including a heat pump refrigeration cycle that circulates to the suction port of the compressor via the four-way valve, on the discharge side of the compressor, An oil separator provided with oil return means for returning lubricating oil to the suction side of the compressor; and a bypass having an on-off valve provided between the oil separator and the outdoor heat exchanger and the expansion mechanism. An air conditioner, wherein the air conditioner is connected by a circuit and controls opening and closing of the on-off valve according to an operation mode. 2. The air conditioner according to claim 1, wherein the bypass circuit is connected to a lower end of the oil separator. 3. The oil return means comprises an oil return pipe having a capillary tube connecting between a lower end of the oil separator and a suction side of the compressor. The air conditioner according to claim 1 or 2. 4. The open / close valve is controlled to be opened during a defrosting operation of the outdoor heat exchanger during a heating operation and closed during a normal heating operation and other operation modes. The air conditioner according to any one of claims 1 to 3, wherein: 5. The air conditioner according to claim 1, wherein the expansion mechanism is an electronic expansion valve.