JPH10141785A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply a discharged refrigerant gas to a refrigerating cycle without bypassing it to the suction side even when the number of operation units of compressors decreases by securing a necessary amount of oil for the compressor. SOLUTION: In a refrigerating cycle in which two compressors 105a and 105b, an outdoor heat exchanger, a decompressor, a room heat exchanger and an accumulator 104 are connected by a refrigerant piping, oil separators 108a and 108b and check valves 109a and 109b are arranged on the respective delivery sides of the compressors 105a and 105b. Oil return tubes 110a and 110b are provided to connect the bottom parts of the oil separators 108a and 108b to the accumulator 104 and suction pipings 111a and 111b with which the accumulator 104 is connected to the compressors 105a and 105b are connected to the accumulator 104. The number of the pipings should be equal to the number of the compressors.

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 multi-air conditioner for air-conditioning a plurality of rooms using a plurality of hermetic compressors, and particularly requires oil in a hermetic container containing a compression mechanism. It relates to the structure around the compressor to secure the quantity.

[0002]

2. Description of the Related Art For example, in a multi-air conditioner using a plurality of hermetic compressors, it is an important technical problem to secure a required oil amount of the compressor in a refrigeration cycle. For example, a refrigeration apparatus described in Japanese Patent Publication No. 7-122522
An oil equalizing pipe communicating with the appropriate oil amount position of each compressor is provided, and an oil separator is provided on the discharge side of each compressor to separate the discharged refrigerant gas and oil, and the separated oil is compressed through an oil return pipe. It is returned to the suction pipe of the machine.

For example, in the air conditioner described in Japanese Patent Publication No. 2-22873, the discharge pipe of each compressor is led to one oil separator, and the refrigerant gas and oil discharged are separated by the oil separator. The returned oil is returned to the accumulator through an oil return pipe provided with a solenoid valve.

Further, for example, the air conditioner described in Japanese Patent Application Laid-Open No. 8-5169 is provided with an oil recovery circuit for connecting an appropriate oil amount position of a closed vessel of each compressor to a suction pipe, and a certain compressor is provided with an oil recovery circuit. The surplus oil is distributed to other compressors.

[0005]

[Problems to be Solved by the Invention]
According to the prior art described in JP-A-122522, when the pressure inside the closed container storing the oil becomes the suction pressure, the oil amount is secured by the oil equalizing pipe communicating with the appropriate oil amount position of each compressor. In other words, in a compressor, as the operating capacity increases, the oil flows out of the closed vessel and the amount of oil decreases, but as the operating capacity increases, the pressure in the closed vessel decreases. By supplying the oil to the compressor having a reduced oil amount, the oil amount is secured.

[0006] The amount of oil held in the refrigeration cycle is reduced by an oil separator. If this is applied to the case where the pressure inside the closed vessel becomes the discharge pressure, the larger the operating capacity, the higher the pressure inside the closed vessel, so the accumulated oil moves to another compressor through the oil equalizing pipe, and When the compressor continues to operate, the larger the operating capacity, the more the oil flows out of the closed container, so the amount of oil decreases,
There was a problem that the oil amount of the compressor could not be secured.

According to the second prior art disclosed in Japanese Patent Publication No. 22873/1990, the solenoid valve of the oil return pipe is opened for a predetermined time when the compressor is started, and the oil separated by the oil separator is returned to the accumulator. ing. However, when a large amount of oil flows out of the sealed container even during a steady operation other than the start operation, the oil cannot be returned from the oil separator, so that the oil amount of the compressor cannot be secured. It is sufficient to open the solenoid valve and return the oil separated by the oil separator to the accumulator during steady operation, but the amount of oil returned from the oil separator cannot be changed. There is a problem in that the amount of refrigerant discharged decreases and the refrigerant gas flows to the accumulator together with the oil, and the amount of refrigerant circulating to the refrigeration cycle decreases.

In the third prior art disclosed in Japanese Patent Application Laid-Open No. 8-5169, the pressure of each suction pipe changes depending on the length and diameter of the suction pipe and the amount of refrigerant circulating through each suction pipe. For this reason, the flow rate of oil distributed from the oil recovery circuit to each compressor changes due to the pressure of each suction pipe, and the oil flow rate required for the compressor does not return, so that there is a problem that the oil amount of the compressor cannot be secured.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a compressor in which a plurality of hermetic compressors in which the discharge pressure in the hermetic container is connected in parallel are provided. While securing the oil amount required for the compressor,
It is an object of the present invention to provide an air conditioner capable of supplying a discharged refrigerant gas to a refrigeration cycle without bypassing the refrigerant gas to a suction side even when the number of operating compressors decreases.

[0010]

Means for Solving the Problems In order to achieve the above object, the configuration of the first invention according to the air conditioner of the present invention is as follows.
A motor unit and a compression mechanism unit are housed in a sealed container, and a plurality of hermetic compressors are connected in parallel to each other so that the inside of the hermetic container has a discharge pressure. The plurality of compressors, a condenser, a decompression device, and an evaporator And an accumulator connected with a refrigerant pipe to form a refrigeration cycle, comprising an oil separator on the discharge side of each of the plurality of compressors and a check valve on an outlet side of the oil separator, An oil return pipe connecting the bottom of each oil separator and the accumulator is provided, and suction pipes connecting the accumulator and the plurality of compressors are connected to the accumulators in the same number as the number of the plurality of compressors. It was done.

With the above construction, the oil and the refrigerant discharged from the compressor are separated by the oil separator, and the separated oil is returned to the accumulator by the oil return pipe. In the accumulator, each suction pipe connected to each compressor is connected to the oil separator. And the refrigerant is sucked together with the refrigerant and distributed to each compressor. Further, when some of the compressors are stopped, the check valve provided at the outlet of the oil separator of the stopped compressor is closed to prevent refrigerant gas discharged from the operating compressor from flowing into the stopped compressor.

[0012] In order to achieve the above object, a second aspect of the invention relates to an air conditioner of the present invention, wherein a plurality of hermetic compressors in which a motor section and a compression mechanism section are housed in a closed container are connected in parallel. In an air conditioner in which a plurality of compressors, a condenser, a decompression device, an evaporator, and an accumulator are connected by a refrigerant pipe to constitute a refrigeration cycle, at least one oil separator is provided on the discharge side of the compressor. Oil return pipes connecting the bottom of the oil separator and the accumulator, the same number as the number of the plurality of compressors connected to the oil separator, and excluding one of the oil return pipes. An electromagnetic valve was provided in the pipe, and the same number of suction pipes as the number of the plurality of compressors were connected to the accumulator, and suction pipes connecting the accumulator and the plurality of compressors were connected. Than it is.

With the above arrangement, the oil and the refrigerant discharged from the compressor are separated by the oil separator, and the separated oil is returned to the accumulator by the oil return pipe. In the accumulator, each suction pipe connected to each compressor is connected to the oil separator. And the refrigerant is sucked together with the refrigerant and distributed to each compressor. Further, when some of the compressors are stopped, by closing the solenoid valves provided on the same number of oil return pipes as the number of stopped compressors, only the required oil flow is returned, and the discharged refrigerant gas is discharged. Prevents the return pipe from flowing to the accumulator.

In order to achieve the above object, a third aspect of the present invention relates to an air conditioner of the present invention in which a motor unit and a compression mechanism are housed in a closed container, and the closed container has a discharge pressure. A plurality of compressors are connected in parallel, and the plurality of compressors, a condenser, a decompression device, an evaporator, and an accumulator are connected by refrigerant piping to form a refrigeration cycle. A check valve is provided on each discharge side of the compressor, and a second oil return pipe that connects an appropriate oil amount position of each closed vessel of the plurality of compressors and the accumulator is provided, and the accumulator and the The same number of suction pipes as the number of the plurality of compressors are connected to the accumulators.

[0015] With the above configuration, the surplus oil of the compressor is discharged to the second
In the accumulator, each suction pipe connected to each compressor draws in the oil from the second oil return pipe together with the refrigerant and distributes the oil to each compressor. Further, when some of the compressors are stopped, the check valve of the stopped compressor is closed to prevent the refrigerant gas discharged from the operating compressor from flowing into the stopped compressor.

In the first, second, and third inventions, the accumulator has a plurality of suction pipes connected to the plurality of compressors, which are connected in parallel. It is shaped like a letter, and has an oil return hole at the lowermost end of its U-shaped curved part,
Each of the suction pipes has an equalizing hole near an outlet inside the accumulator. According to the above configuration, an oil flow rate proportional to the amount of circulating refrigerant flowing through the plurality of suction pipes can be sucked from each oil return hole and sent to the compressor. The amount of oil flow to be sucked can be selected depending on the diameter of the oil return hole and the equalizing hole.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
This will be described with reference to FIG. Embodiment 1 FIGS. 1 to 5 show a first embodiment.
This will be described with reference to FIG. FIG. 1 is a refrigeration cycle system diagram of an air conditioner showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of an operation method of a compressor in the refrigeration cycle of FIG. 1, and FIG.
Is a system diagram around the compressor according to the first embodiment of the present invention, FIG. 4 is a configuration diagram of an accumulator according to the embodiment of the present invention, and FIG. 5 is a diagram illustrating an oil discharge rate of the compressor according to the embodiment of the present invention. FIG. 6 is a characteristic diagram.

The refrigeration cycle of the air conditioner shown in FIG.
The outdoor unit 100 and two indoor units 200 and 300 are connected by a refrigerant gas pipe 121 and a refrigerant liquid pipe 122. The outdoor unit 100 includes a compressor 105, a four-way valve 1
06, outdoor heat exchanger 101, outdoor refrigerant flow control valve 10
2, outdoor fan 103, accumulator 104, accumulator introduction pipe 114, suction pipes 111a, 111b,
It comprises a receiver 107 and an outdoor controller 151.

Here, the compressor 105 is composed of an inverter compressor 105a whose motor speed can be varied and a constant speed compressor 105b whose motor speed is constant. Although not shown and described, the compressor 105 is a hermetic compressor in which an electric motor section and a compression mechanism section are housed in a hermetically sealed container, and the inside of the hermetically sealed container has a discharge pressure.

The compressor 105 exhibits the capability shown in FIG. FIG. 2 shows the required capacity of the compressor 105 on the horizontal axis and the capacity of the compressor 105 on the vertical axis. The inverter compressor 105a whose rotation speed can be varied has a small required capacity (a) to a medium required (d). Between the lowest frequency b and the highest frequency c. That is, its ability is abcd
It is represented by an area. Further, the constant speed compressor 105b exhibits the capability of the constant frequency e to f from the required capacity (d) to the large (g). That is, the capability is represented by a defg area.

By simultaneously operating the inverter compressor 105a and the constant speed compressor 105b in parallel, the capacity from the lowest frequency c to the highest frequency h is exhibited between the required capacity (d) and the large capacity (g). That is, the ability is represented by the cdgh region. Further, the outdoor controller 151 controls the on / off of the inverter compressor 105a and the constant speed compressor 105b, the rotation speed of the motor of the inverter compressor 105a, and the opening degree of the outdoor refrigerant flow control valve 102.

The indoor unit 200 includes an indoor heat exchanger 201, an indoor refrigerant flow control valve 202, an indoor fan 203, a temperature detector 204 for detecting the temperature of intake air, and an indoor controller 208. Here, the signal of the temperature detector 204 is input to the indoor controller 208, and
The indoor controller 208 controls the opening of the indoor refrigerant flow control valve 202.

The indoor unit 300 comprises an indoor heat exchanger 301, an indoor refrigerant flow control valve 302, an indoor fan 303, a temperature detector 304 for detecting the temperature of intake air, and an indoor controller 308. Here, the signal of the temperature detector 304 is input to the indoor controller 308, and
The indoor controller 308 controls the opening of the indoor refrigerant flow control valve 302. The indoor controllers 208 and 308 and the outdoor controller 151 are connected by a transmission line 123.

Next, the flow of the refrigerant during the cooling operation will be described. In FIG. 1, solid arrows shown in the refrigerant gas pipe 121 and the refrigerant liquid pipe 122 indicate the flow direction of the refrigerant. Solid arrows in the indoor units 200 and 300 indicate the direction of air flow. As shown in FIG. 1, the compressor 105 (105
The high-temperature and high-pressure refrigerant gas discharged from a, 105b) passes through the four-way valve 106, enters the outdoor heat exchanger 101, and exchanges heat with outdoor air sent by the outdoor fan 103 to condense. Thereafter, the condensed refrigerant passes through the outdoor refrigerant flow control valve 102 which is fully opened, and is separated into gas and liquid by the receiver 107. Then, the liquid refrigerant exits the outdoor unit 100, and the refrigerant liquid pipe 1
After passing through 22, it is sent to indoor units 200 and 300.

The liquid refrigerant entering the indoor unit 200 is depressurized by the indoor refrigerant flow control valve 202, enters the indoor heat exchanger 201, and exchanges heat with the indoor air sent by the indoor fan 203 to evaporate. At this time, the indoor air is cooled and blown out from the indoor unit 200. The evaporated low-temperature low-pressure gas refrigerant exits the indoor unit 200. On the other hand, the refrigerant that has entered the indoor unit 300 is reduced in pressure by the indoor refrigerant flow control valve 302, enters the indoor heat exchanger 301, and exchanges heat with the indoor air sent by the indoor fan 303, similarly to the indoor unit 200 described above. And evaporate. At this time, the indoor air is cooled and blown out from the indoor unit 300.

The evaporated low-temperature low-pressure gas refrigerant is supplied to the indoor unit 30.
After exiting 0, the refrigerant merges with the refrigerant coming out of the indoor unit 200 and is sent to the outdoor unit 100 through the refrigerant gas pipe 121.
The refrigerant that has entered the outdoor unit 100 is supplied to the four-way valve 106, the accumulator introduction pipe 114, the accumulator 104, and the suction pipe 1.
It is sucked into the compressor 105 through 11a and 111b, compressed and discharged again, and this cycle is repeated thereafter.

Next, the flow of the refrigerant during the heating operation will be described. In FIG. 1, dashed arrows shown in the refrigerant gas pipe 121 and the refrigerant liquid pipe 122 indicate the flow direction of the refrigerant. The high-temperature and high-pressure refrigerant gas discharged from the compressor 105 (105a, 105b) passes through the four-way valve 106 and passes through the gas pipe 12
1 and is sent to the indoor units 200 and 300. Indoor unit 2
00 enters the indoor heat exchanger 201 and exchanges heat with the indoor air sent by the indoor fan 203 to condense. At this time, the room air is warmed. Then, the condensed refrigerant exits the indoor unit 200 through the indoor refrigerant flow control valve 202. On the other hand, the refrigerant that has entered the indoor unit 300 condenses similarly to the indoor unit 200 and exits the indoor unit 300. The refrigerants that have exited the indoor units 200 and 300 join and enter the outdoor unit 100 through the liquid pipe 122.

The refrigerant that has entered the outdoor unit 100 first enters the receiver 107 and is separated into gas and liquid.
07, is decompressed by the indoor refrigerant flow control valve 102, enters the outdoor heat exchanger 101, exchanges heat with outdoor air sent by the outdoor fan 103, evaporates, becomes a low-temperature low-pressure gas refrigerant, and becomes a four-way valve 106. Accumulator introduction pipe 114, accumulator 104, suction pipe 111a,
It is sucked into the compressor 105 through 111b, compressed and discharged again. This cycle is repeated thereafter.

Next, the structure around the compressor in the refrigeration cycle of the air conditioner of FIG. 1 will be described with reference to FIG. Accumulator 104 and compressors 105a and 105b
Are connected by suction pipes 111a and 111b provided in parallel. Compressors 105a, 105b
Oil separators 108a, 108a
8b are provided in parallel, and the oil separators 108a,
Check valves 109a, 109b are provided at the outlet of 108b, respectively.
Is provided. Oil separators 108a, 108
The bottom of b and the accumulator introduction pipe 114 are connected by oil return pipes 110a and 110b provided with a capillary tube.

As shown in FIG. 4, the accumulator 104 is provided with suction pipes 111a, 1a in the accumulator 104.
Reference numeral 11b denotes a U-pipe shape, and oil return holes 116a and 116b are respectively drilled at the lowermost end of the bent portion, and a pressure equalizing hole 115 is provided near the outlet of the accumulator 104.
a, 115b are perforated. The oil return hole 116
a and 116b are perforated at the same horizontal position.

With this configuration, the suction pipe 111
The oil flow rate proportional to the amount of circulating refrigerant flowing through the oil return holes 116a and 116b can be sucked from the oil return holes 116a and 116b and sent to the compressors 104a and 105b. The amount of oil flow to be sucked is determined by oil return holes 116a and 116b.
And the diameter of the equalizing holes 115a and 115b.

Next, the operation for securing the oil amount of the compressor in the above embodiment will be described. Compressors 105a, 105
b and the oil discharged from the oil separator 1
08a and 108b, gas-liquid separation is performed, and the refrigerant gas flows through the check valves 109a and 109b to the refrigeration cycle. The oil separated by the oil separators 108a and 108b flows into the accumulator introduction pipe 114 through the oil return pipes 110a and 110b, and enters the accumulator 104.

The oil that has entered the accumulator 104 draws in an oil flow proportional to the amount of refrigerant discharged from the compressors 105a and 105b from the respective oil return holes 116a and 116b.
Each of the compressors 1 passes through the suction pipes 111a and 111b.
05a, 105b. Here, the oil discharge rate of the compressor (= the amount of oil discharged from the compressor / the amount of refrigerant discharged from the compressor) increases as the amount of oil in the compressor increases, as shown in FIG. Further, the oil discharge rate increases as the amount of refrigerant discharged from the compressor increases. When the motor of the inverter compressor 105a is operated at the minimum number of revolutions, the refrigerant discharge rate decreases and the oil discharge rate also decreases.
The constant speed compressor 105b has a larger refrigerant discharge amount than the inverter compressor 105a, and therefore has a higher oil discharge rate.

For example, assuming that the oil amount in the compressor before the operation of each compressor is V0, the oil discharge rate of the inverter compressor 105a immediately after the operation becomes point a, and the oil discharge rate of the constant speed compressor 105b. The rate is point b. The discharged oil is separated by the oil separators 108a and 108b as described above, and an oil flow proportional to the discharged refrigerant amount is distributed from the accumulator 104 to each compressor. Therefore, the oil amount of the inverter compressor 105a increases, and the oil amount of the constant speed compressor 105b decreases, and is stabilized at points a 'and b', respectively. When the point b 'becomes smaller than the minimum oil amount Vmin, oil may be added.

When the constant speed compressor 105b stops,
The high pressure side is shut off by the check valve 109b, and the compressor 10
5b and the oil separator 108b have a low pressure, and the refrigerant and the oil stop flowing. Inverter compressor 1
The oil discharged by 05a is separated by an oil separator 108a, and the separated oil enters the accumulator 104 through the oil return pipe 110a and the accumulator introduction pipe 114, returns to the inverter compressor 105a from the suction pipe 111a, and returns to the inverter compressor 105a. The oil amount of 105a is secured.
According to the present embodiment, since the stop compressor has a low pressure, the refrigerant does not condense in the compressor, so that the shortage of the refrigerant does not occur.

[Embodiment 2] FIG. 6 shows a second embodiment of the present invention.
It is a system diagram around a compressor concerning an embodiment. In the drawing, those having the same reference numerals as those in FIG. 3 are the same as those in the first embodiment, and the refrigeration cycle of the air conditioner applied in FIG. 6 is the same as that in FIG. Accumulator 104 and compressor 105
a and 105b are suction pipes 111a and 111 provided in parallel.
b.

An oil separator 108 is provided on the discharge side of the compressors 105a and 105b.
A check valve 109 is provided at the outlet of 08. The bottom of the oil separator 108 and the accumulator introduction pipe 114
Are connected by oil return pipes 110a and 110b provided with capillaries. Further, a solenoid valve 112 is attached to the oil return pipe 110b. The configuration of the accumulator 104 is the same as that in FIG.

Next, the operation for securing the oil amount of the compressor in the embodiment of FIG. 6 will be described. Two compressors 105
When a and 105b are operating, the solenoid valve 112 is opened. The refrigerant gas and oil discharged from the compressors 105a and 105b enter the oil separator 108 and are separated into gas and liquid. The refrigerant gas flows through the check valve 109 to the refrigeration cycle. The oil separated by the oil separator 108 flows through the oil return pipes 110a and 110b, flows into the accumulator introduction pipe 114, enters the accumulator 104, and the oil amount of the compressor is secured by the same operation as in the embodiment of FIG.

When the constant speed compressor 105b stops, the solenoid valve 112 is closed. The oil discharged from the inverter compressor 105a is separated by the oil separator 108, and the separated oil enters the accumulator 104 through the oil return pipe 110a and the accumulator introduction pipe 114, and returns to the inverter compressor 105a from the suction pipe 111a. The oil amount of the inverter compressor 105a is secured.

[Embodiment 3] FIG. 7 shows a third embodiment of the present invention.
It is a system diagram around a compressor concerning an embodiment. In the figure, those having the same reference numerals as those in FIG. 3 are the same as those in the first embodiment, and the refrigeration cycle of the air conditioner applied in FIG. 7 is the same as that in FIG. Accumulator 104 and compressor 105
a and 105b are suction pipes 111a and 111 provided in parallel.
b. Compressor 105a,
Check valves 109a, 109b are connected in parallel to the discharge side of 105b.
Is provided. Further, the appropriate oil amount positions of the compressors 105a and 105b and the accumulator introduction pipe 114 are connected by second oil return pipes 113a and 113b having capillaries. The configuration of the accumulator 104 is the same as that in FIG.

Next, the operation for securing the oil amount of the compressor in the embodiment of FIG. 7 will be described. As described in the embodiments of FIGS. 3 and 6, the oil amounts of the compressors 105a and 105b are biased by the amount of refrigerant discharged from the compressors.
The oil that has accumulated more than the appropriate oil amount is stored in the second oil return pipe 113a,
113b, the oil flows to the accumulator 104 and is distributed to the respective compressors 105a and 105b, so that the oil amount of the compressor reduced by the bias can be increased,
The oil volume of the compressor is secured.

When the constant speed compressor 105b stops, the check valve 109b shuts off the high pressure side.
b becomes a low pressure, and the refrigerant and the oil stop flowing. The oil discharged from the inverter compressor 105a goes through the refrigeration cycle, enters the accumulator 104 through the accumulator introduction pipe 114, returns to the inverter compressor 105a from the suction pipe 111a, and secures the oil amount of the inverter compressor 105a. According to the present embodiment, since the stop compressor has a low pressure, the refrigerant does not condense in the compressor, so that the shortage of the refrigerant does not occur.

Fourth Embodiment FIG. 8 is a system diagram around a compressor according to a fourth embodiment of the present invention. In the figure, those having the same reference numerals as those in FIG. 3 are the same as those in the first embodiment. In the embodiment of FIG. 8, two compressors in the embodiment shown in FIG. 7 are replaced with four compressors.
An oil separator 108a is provided between the compressor 105a and the check valve 109a.
Is connected to the accumulator introduction pipe 114 by an oil return pipe 110a having a capillary.

Next, the operation for securing the oil amount of the compressor in the embodiment of FIG. 8 will be described. The oil that has accumulated more than the appropriate amount is the second oil return pipe 113a, 113b, 113c,
It flows to the accumulator 104 by 113d. The oil discharged from the inverter compressor 105a is separated by the oil separator 108a, and the separated oil enters the accumulator 104 through the oil return pipe 110a and the accumulator introduction pipe 114, and passes through the second oil return pipe. Compressor 105a, 105b, 10
5c and 105d, and the oil amount of the compressor is secured. The embodiment of FIG. 8 has an oil separator compared to the embodiment of FIG. 7, so that the amount of oil entering the refrigeration cycle can be reduced, the oil amount of the compressor increases accordingly, and the oil amount can be easily secured. Become.

As described above, the refrigeration cycle of this embodiment has the following effects. The oil separator separates the oil mixed with the discharged refrigerant to reduce the amount of oil accumulated in the refrigeration cycle, and returns the separated oil to the accumulator, so that the accumulator distributes oil proportional to the discharge amount of each compressor. . Thereby, the oil amount of the compressor is secured. Further, the check valve on the discharge side does not cause the refrigerant discharged from the other operating compressor to flow into the stop compressor, flow to the low-pressure side through the oil return pipe, and reduce the refrigerant circulation amount flowing to the refrigeration cycle. .

Also, solenoid valves are provided on a plurality of oil return pipes from the oil separator, and when the compressor is stopped, the same number of solenoid valves as the stopped compressor are closed, so that an appropriate oil flow can be obtained from the other oil return pipes. As described above, the amount of oil in the operating compressor is secured as described above, and by closing the solenoid valve, the discharged refrigerant is prevented from flowing from the oil return pipe to the low pressure side, and the refrigerant circulation amount flowing to the refrigeration cycle is reduced. Secure. Further, the excess oil accumulated in the compressor through the second oil return pipe flows into the accumulator, and the oil is distributed to the compressors, so that the oil amount of the compressor is ensured.

[0047]

As described above in detail, according to the present invention, for a compressor in which a plurality of hermetic compressors are connected in parallel, the discharge pressure in the hermetic container is reduced, the amount of oil required for the compressor is reduced. In addition to this, it is possible to provide an air conditioner capable of supplying the refrigerant gas to the refrigeration cycle without bypassing the refrigerant gas discharged to the suction side even when the number of operating compressors decreases.

[Brief description of the drawings]

FIG. 1 is a refrigeration cycle system diagram of an air conditioner showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an operation method of a compressor in the refrigeration cycle of FIG.

FIG. 3 is a system diagram around a compressor according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram of an accumulator according to the embodiment of the present invention.

FIG. 5 is a characteristic diagram of an oil discharge rate of the compressor according to the embodiment of the present invention.

FIG. 6 is a system diagram around a compressor according to a second embodiment of the present invention.

FIG. 7 is a system diagram around a compressor according to a third embodiment of the present invention.

FIG. 8 is a system diagram around a compressor according to a fourth embodiment of the present invention.

[Explanation of symbols]

100: outdoor unit, 101: outdoor heat exchanger, 104: accumulator, 105, 105a, 105b, 105c,
105d: compressor, 106: four-way valve, 108, 108
a, 108b ... oil separator, 109, 109a,
109b, 109c, 109d ... check valve, 110a, 1
10b ... oil return pipe, 111a, 111b, 111c, 1
11d: suction pipe, 112: solenoid valve, 113a, 113
b, 113c, 113d: second oil return pipe, 121: refrigerant gas pipe, 122: refrigerant liquid pipe, 200, 300: indoor unit, 201, 301: indoor heat exchanger.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasutaka Yoshida 390 Muramatsu, Shimizu-shi, Shizuoka Pref. Air Conditioning Systems Division, Hitachi, Ltd.

Claims (4)

[Claims] An electric motor section and a compression mechanism section are housed in a closed container, and a plurality of hermetic compressors are connected in parallel so that the discharge pressure in the closed container is obtained. In an air conditioner configured by connecting a pressure reducing device, an evaporator, and an accumulator with a pipe to form a refrigeration cycle, an oil separator on a discharge side of each of the plurality of compressors and a check valve on an outlet side of the oil separator. Respectively provided in parallel, an oil return pipe connecting the bottom of each oil separator and the accumulator, a suction pipe connecting the accumulator and the plurality of compressors, the number of the plurality of compressors An air conditioner characterized by being connected to the accumulator in the same number as that of the accumulator. 2. A plurality of hermetic compressors each containing a motor section and a compression mechanism section in a closed vessel are connected in parallel, and the plurality of compressors are connected to a condenser, a decompression device, an evaporator, and an accumulator. An air conditioner configured with a refrigeration cycle connected by piping, comprising at least one oil separator on the discharge side of the plurality of compressors, and an oil return pipe connecting the bottom of the oil separator and the accumulator, The same number as the number of the plurality of compressors connected to the oil separator is provided, and the oil return pipe except one of the oil return pipes is closed when one of the plurality of compressors stops. Providing an electromagnetic valve for valve connection, the suction pipe connecting the accumulator and the plurality of compressors is connected to the accumulator in parallel by the same number as the number of the plurality of compressors. An air conditioning apparatus, characterized in that. 3. A closed casing housings an electric motor section and a compression mechanism section, and a plurality of hermetic compressors having a discharge pressure in the closed vessel are connected in parallel, and the plurality of compressors, the condenser, In an air conditioner configured by connecting a pressure reducing device, an evaporator, and an accumulator with piping to form a refrigeration cycle, a check valve is provided on each discharge side of the plurality of compressors, and each of the plurality of compressors is provided. A second oil return pipe connecting the proper oil amount position of the closed container and the accumulator, and a suction pipe connecting the accumulator and the plurality of compressors, the same number of the plurality of compressors An air conditioner, wherein the air conditioner is connected to the accumulator in number. 4. The accumulator has a plurality of suction pipes connected to the plurality of compressors connected in parallel, and each of the plurality of suction pipes has a U-shape in the accumulator, and has a U-shaped curved portion. The air conditioner according to any one of claims 1 to 3, further comprising an oil return hole at the lowermost end of each of the first and second holes, and an equalizing hole near each of the accumulator outlets of the suction pipe.