JP2002349938A - Refrigeration unit and control method for its oil return - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a freezing apparatus and a control method for its oil return where freezer oil is prevented from becoming insufficient for a compressor of an outdoor unit, and reliability is improved sharply. SOLUTION: In a freezing apparatus in which a plurality of indoor units 1A, 1B, and 1C operable individually as need are connected in parallel to an outdoor unit 10, there is provided an oil return control means 17 so that freezer oil accumulated on the side of a plurality of or one stationary indoor units 1A, 1B, and 1C is returned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration apparatus and an oil return control method therefor, for example, applied to a refrigeration apparatus in which a plurality of indoor units are arranged in parallel with an outdoor unit and an oil return control method therefor. It is suitable.

[0002]

2. Description of the Related Art Conventionally, as a refrigerating apparatus of this type, for example, a multi-type package air conditioner in which a plurality of indoor units are connected in parallel to an outdoor unit is known. This multi-type package air conditioner includes, for example, a plurality of compressors, an oil separator (oil separator), an air heat exchanger that functions as a condenser during cooling and functions as an evaporator during heating, and an accumulator. An outdoor unit having, an expansion valve, during cooling, functioning as an evaporator, during heating,
Generally, an indoor unit having an air heat exchanger functioning as a condenser is sequentially connected by piping to form a refrigeration cycle.

[0003] In such a refrigeration system, a plurality of indoor units are all in operation during operation, and all the indoor units are in a stopped state when stopped.

[0004] Therefore, in the outdoor unit, the refrigerating machine oil returned from each indoor unit is separated by, for example, an oil separator so that the refrigerating machine oil of the compressor does not run short.
Once through an oil regulator etc. at a higher position than each compressor, an appropriate amount is supplied to each compressor, or the refrigerating machine oil separated by this oil separator is passed through an oil return pipe and then compressed. After returning to the compressor, the oil level was adjusted by oil equalizing pipes connecting the respective compressors, so that the refrigerating machine oil was periodically moved between the compressors.

[0005]

In recent years, the areas in charge of each indoor unit have been finely partitioned, and the set temperatures and the like may be different in each area. It is becoming.

However, when each indoor unit is individually operated as described above, if the number of operating indoor units is small, the refrigerating machine oil circulating together with the refrigerant accumulates in the pipe of the stopped indoor unit, and the outdoor unit Since the unit does not return to the unit, there is a problem that refrigeration oil to be used in the outdoor unit is insufficient.

[0007] In this case, the compressor of the outdoor unit may be burned and damaged due to a shortage of refrigerating machine oil.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a refrigerating apparatus which can prevent a shortage of refrigerating machine oil in a compressor of an outdoor unit and can significantly improve reliability. And an oil return control method thereof.

[0009]

In order to solve the above problems, the present invention employs the following means. Claim 1
In the refrigerating apparatus described in the above, in the refrigerating apparatus in which a plurality of indoor units performing individual operation as needed are connected in parallel to an outdoor unit, a plurality of indoor units or one of the indoor units is stopped. Oil return control means is provided for returning refrigeration oil collected on the side to the outdoor unit.

According to the refrigerating apparatus described above, the oil return control means for returning the refrigerating oil collected in the stopped plurality or one indoor unit to the outdoor unit is provided, so that the indoor unit side is provided. The refrigerating machine oil collected in the outdoor unit is collected in the outdoor unit, and the shortage of the refrigerating machine oil in the compressor of the outdoor unit is prevented.

According to a second aspect of the present invention, there is provided an oil return control method for a refrigeration system in which a plurality of indoor units performing individual operations as necessary are connected in parallel to an outdoor unit. In the return control method, the first step of operating a plurality or one of the indoor units by closing the flow rate adjusting means of each of the indoor units other than the indoor unit to be operated, and every time a predetermined time elapses,
And a second step of opening the flow rate adjusting means of the stopped indoor unit for a predetermined time.

According to this oil return control method for a refrigeration system,
The first step of operating a plurality of or one indoor unit by closing the flow rate adjusting means of each indoor unit other than the indoor unit to be operated, and the operation of the stopped indoor unit every time a predetermined time elapses Providing a second step of opening the flow rate adjusting means for a predetermined time to collect the refrigerating machine oil accumulated on the indoor unit side in the outdoor unit and prevent the compressor of the outdoor unit from running out of the refrigerating machine oil. To prevent.

According to a third aspect of the present invention, in the oil return control method for a refrigeration system according to the second aspect, the outdoor unit compresses in response to a change in load of each of the indoor units individually operated. The present invention is characterized in that the compressor frequency is adjusted by changing the inverter frequency of the compressor. According to the oil return control method for the refrigeration system, the outdoor unit changes the inverter frequency of the compressor in accordance with the fluctuation of the load of each of the individually operated indoor units and adjusts the capacity, thereby circulating the refrigerant. To speed up the recovery of refrigeration oil.

Further, according to a fourth aspect of the present invention, in the oil return control method for a refrigeration system according to the second or third aspect,
In the second step, the expansion valves of the stopped indoor units are sequentially opened one by one. According to the oil return control method of the refrigeration apparatus,
In the second step, the expansion valves of the stopped indoor units are sequentially opened one by one, so that the expansion valves of all the indoor units required when the expansion valves of all the indoor units are simultaneously opened are simultaneously opened. Is reduced to a small frequency for one vehicle, and the refrigerating machine oil is returned at the minimum necessary flow velocity.

According to a fifth aspect of the present invention, in the oil return control method for a refrigerating apparatus according to the second, third or fourth aspect, the flow rate adjusting means is an electronic expansion valve. According to the oil return control method of the refrigeration apparatus,
Since the flow rate adjusting means is a highly versatile and easily available electronic expansion valve, the indoor unit is configured simply and inexpensively.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus according to one embodiment of the present invention. In FIG. 1, 1A,
1B and 1C denote indoor units, respectively, and are sequentially connected in parallel to the outdoor unit 10. In addition,
In this embodiment, a case where three indoor units 1A, 1B, and 1C are connected in parallel to the outdoor unit 10 will be described. However, the present invention is not limited to this. Then, it goes without saying that the number of indoor units can be increased or decreased.

The indoor units 1A, 1B and 1C are provided with air heat exchangers 2A, 2B and 2C and electronic expansion valves V1A, V1B and V1C, respectively, as flow rate adjusting means. The air heat exchangers 2A, 2B, and 2C are discharged from the air heat exchangers 2A, 2B, and 2C and sent to the outdoor unit 10. During heating, the refrigerant sent from the outdoor unit 10 is used as an air heat exchanger as a heater (condenser). 2A, 2B,
It is designed to fit in 2C.

The outdoor unit 10 includes the accumulator 1
1, for example, a plurality of compressors 12A, 12B, and an oil separator 13 corresponding to each of the compressors 12A, 12B.
A, 13B, an oil equalizing pipe 14 communicating the compressors 12A, 12B, an air heat exchanger 15A, 15B functioning as a condenser during cooling, and functioning as an evaporator during heating, a strainer 16, And a switching valve V2.

In this refrigerating apparatus, during cooling, the air heat exchangers 2A, 2B, 2C of the indoor units 1A, 1B, 1C are used.
The refrigerant that has passed through 2C is sent to the four-way switching valve V2 through the refrigerant pipe, as indicated by the solid line arrow in the figure.
2 through the accumulator 11, and from the accumulator 11, the compressor 12A
And / or 12B.

At this time, in addition to the refrigerant, the accumulator 11 contains refrigerating machine oil that is sent together with the refrigerant.
Each is sent to the corresponding compressor 12A and / or 12B through the refrigerant pipe.

The refrigerant sent to the compressors 12A and 12B is compressed here to become a high-temperature and high-pressure gas refrigerant, and passes through a refrigerant pipe to the corresponding oil separators 13A and 13B.
After passing through the four-way switching valve V2, the air heat exchanger 15
A, 15B.

Between the compressors 12A and 12B, the refrigerating machine oil sent from the accumulator 11 is transferred to the compressor 12B or 12A operating from the stopped compressor 12A or 12B, or to the compressor 12A or 12A.
When both of the compressors 12B are operating, the compressors 12A and 12B are exchanged with the compressors 12B and 12A via the oil equalizing pipe 14 to prevent damage due to a shortage of the refrigerating machine oil. Has been made.

At this time, the oil separators 13A, 13A
In B, the refrigerating machine oil in the gas refrigerant sent from the corresponding compressors 12A and 12B is separated, the gas refrigerant is sent to the four-way switching valve V2 through the refrigerant pipe, and the refrigerating machine oil is sent through the oil pipe. Return to the corresponding compressors 12A, 12B.

The gas refrigerant sent to the air heat exchangers 15A and 15B is cooled by air and condensed into a liquid refrigerant, and then passes through a strainer 16 through a refrigerant pipe, and passes through the electronic units of the indoor units 1A, 1B and 1C. Expansion valves V1A, V1
B, sent to V1C.

These electronic expansion valves V1A, V1B, V1C
The liquid refrigerant that has entered is adiabatically expanded by being throttled here to become a gas-liquid two-phase refrigerant, passes through refrigerant pipes and enters the air heat exchangers 2A, 2B, and 2C.
The indoor air is cooled by the latent heat of evaporation of the refrigerant in 2B and 2C to evaporate.

The refrigerant thus vaporized and vaporized (that is, gas refrigerant) is sent again to the outdoor unit 10 through the refrigerant pipe.

On the other hand, in this refrigeration system, during heating, the air heat exchangers 2A, 2B, 2C of the indoor units 1A, 1B, 1C are used.
The refrigerant discharged from C is indicated by a dashed arrow in the figure,
The refrigerant is sent to the electronic expansion valves V1A, V1B, and V1C through the refrigerant pipes, and is adiabatically expanded by being squeezed here to form a gas-liquid two-phase refrigerant. Put in.

The refrigerant put in the air heat exchangers 15A and 15B is cooled by the latent heat of vaporization and evaporates into a gaseous refrigerant, and then is sent to the accumulator 11 through the refrigerant pipe via the four-way switching valve V2. .

The gas refrigerant sent to the accumulator 11 is supplied to the corresponding compressor 12A,
12B, where it is compressed to become a high-temperature, high-pressure gas refrigerant, which is sent to the corresponding oil separators 13A, 13B through the refrigerant pipe.

At this time, the movement of the refrigerating machine oil from the accumulator 11 to the corresponding compressors 12A and 12B is performed such that the oil is sent to the corresponding compressors 12A and / or 12B through the respective refrigerant pipes, similarly to the above-described cooling. I have.

The oil separators 13A, 13A
In 3B, the refrigerating machine oil in the gas refrigerant sent from the corresponding compressors 12A and 12B is separated, and the gas refrigerant is passed through the refrigerant pipe via the four-way switching valve V2,
Air heat exchanger 2A of each indoor unit 1A, 1B, 1C,
2B and 2C, and the refrigerating machine oil is returned to the corresponding compressors 12A and 12B through oil piping.

The gas refrigerant introduced into the air heat exchangers 2A, 2B, 2C of the indoor units 1A, 1B, 1C is cooled by air to be condensed into a liquid refrigerant, and then passed through a refrigerant pipe to an electronic expansion valve V1A. , V1B, V1C,
By being squeezed here, it is adiabatically expanded to become a gas-liquid two-phase refrigerant, and is sent again to the outdoor unit 10 through the refrigerant pipe.

In practice, in such a refrigerating apparatus, during such a series of cooling / heating operations, the user stops via a remote controller (so-called remote controller), abnormally stops, or reaches a set temperature. If, for example, the indoor units 1B and 1C are stopped due to thermo-off or the like in which the refrigerant and the fan stop, the oil return control unit 17 serving as the oil return control means sends the valve opening signal S1 to the indoor unit 1A when the operation starts. At the same time, the valve closing signal S2 is sent to the indoor units 1B and 1C.

Thus, the stopped indoor unit 1
The electronic expansion valves V1B and V1C of B and 1C are closed, and the electronic expansion valve V1A of the indoor unit 1A is opened.

Therefore, the refrigerant containing the refrigerating machine oil discharged from the outdoor unit 10 is discharged to the stopped indoor unit 1B,
Indoor unit 1A operating without passing through the 1C side piping
The refrigerant circuit as described above is circulated only through the side piping.

In the refrigerating apparatus, when such low-load operation is performed for a predetermined time (for example, 10 hours), the oil return control unit 17 outputs the oil return control signal S3 to the stopped indoor units 1B and 1C. And the electronic expansion valves V1B, V1B
1C one by one for a predetermined time (for example, cooling: 1 [minute]
Heating: 4 minutes) Leave open.

At this time, the stopped indoor unit 1
If two electronic expansion valves V1B and V1C of B and 1C are opened at the same time, a correspondingly higher frequency is required and the flow rate of the refrigerant must be increased.
1B and V1C are opened and closed one by one.

In the case of this embodiment, the compressor 12A of the outdoor unit 10 is of a variable capacity (inverter) type. Thereby, at the time of opening / closing operation of the electronic expansion valves V1B and V1C, the inverter control signal S10 is sent by the oil return control unit 17, thereby increasing the operating frequency of the compressor 12A and increasing the refrigerant circulation amount. Recovery of refrigerating machine oil can be accelerated.

As described above, in this refrigerating apparatus, the electronic expansion valves V1B and V1C of the stopped indoor units 1B and 1C are opened and closed under the control of the oil return control unit 17 to stop these units. Indoor units 1B, 1C
Since the refrigerating machine oil accumulated in the piping on the side can be collected in the outdoor unit, shortage of the refrigerating machine oil in the compressor of the outdoor unit can be prevented.

In the above-described embodiment,
Although the present invention has been described for a case in which three indoor units 1A, 1B, and 1C are applied to a refrigerating apparatus that is connected to the outdoor unit 10 in parallel, the present invention is not limited to this. As the refrigerating device, those having various other configurations can be widely applied, and the number of indoor units is not limited to three.

In this embodiment, the case where the outdoor unit 10 is provided with the plurality of compressors 12A and 12B has been described, but the present invention is not limited to this.
The compressor of the outdoor unit 10 may be singular or plural.

[0043]

As described above, according to the present invention, in the refrigerating apparatus, the oil return control means for returning the refrigerating oil accumulated in the stopped or one indoor unit to the outdoor unit. , The refrigerating machine oil accumulated on the indoor unit side, which was difficult to recover, can be collected in the outdoor unit, thereby preventing shortage of the refrigerating machine oil in the compressor of the outdoor unit. Thus, a refrigeration apparatus that can significantly improve reliability can be realized.

Further, according to the present invention, in the oil return control method for a refrigerating apparatus, a plurality of or one indoor unit is operated by closing the flow rate adjusting means of each indoor unit other than the operated indoor unit. An indoor unit which has been difficult to collect by providing a first step and a second step of opening the flow control means of the stopped indoor unit for a predetermined time every time a predetermined time elapses Since the refrigerating machine oil accumulated on the side can be collected in the outdoor unit, it is possible to prevent a shortage of the refrigerating machine oil in the compressor of the outdoor unit beforehand, and thus the refrigerating apparatus can significantly improve the reliability. Oil return control method can be realized.

In addition, according to the oil return control method of the refrigerating apparatus, the outdoor unit changes the inverter frequency of the compressor in accordance with the fluctuation of the load of each of the individually operated indoor units to adjust the capacity. Further, it is possible to accelerate the recovery of the refrigerating machine oil by increasing the circulation amount of the refrigerant.

Further, according to the oil return control method for the refrigerating apparatus, in the second step, the expansion valves of the stopped indoor units are sequentially opened one by one, whereby the expansion of all the indoor units is performed. Since the large frequency required for all the expansion valves required when the valves are simultaneously opened can be suppressed to a small frequency corresponding to one expansion valve, the refrigerating machine oil can be returned at the minimum necessary flow velocity.

Further, according to the oil return control method for the refrigerating apparatus, the indoor unit can be simply and inexpensively constructed because the flow rate adjusting means is a highly versatile and easily available electronic expansion valve. it can.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus according to one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1A, 1B, 1C Indoor unit 2A, 2B, 2C Air heat exchanger 10 Outdoor unit 11 Accumulator 12A, 12B Compressor 13A, 13B Oil separator 14 Equalizing pipe 15A, 15B Air heat exchanger 16 Strainer 17 Oil return control unit (oil) Return control means) V1A, V1B, V1C Electronic expansion valve V2 Four-way switching valve

Claims (5)

[Claims] 1. A refrigeration system in which a plurality of indoor units performing individual operation as required are connected in parallel to an outdoor unit, respectively. A refrigeration apparatus comprising oil return control means for returning accumulated refrigeration oil to the outdoor unit. 2. An oil return control method for a refrigeration system in which a plurality of indoor units performing individual operation as needed are connected in parallel to an outdoor unit, wherein each of the indoor units other than the indoor unit to be operated is provided. A first step of operating a plurality of or one of the indoor units by closing the flow control means of the above, and opening the flow control means of the stopped indoor unit for a predetermined time every time a predetermined time elapses And a second step of setting a state. 3. The outdoor unit adjusts the capacity of the compressor by changing an inverter frequency of the compressor in accordance with a change in load of each of the indoor units that individually operate. 3. The oil return control method for a refrigeration apparatus according to 2. 4. The oil return of the refrigerating apparatus according to claim 2, wherein in the second step, the expansion valves of the stopped indoor units are sequentially opened one by one. Control method. 5. The oil return control method for a refrigeration system according to claim 2, wherein said flow rate adjusting means comprises an electronic expansion valve.