JP2001280719A - Refrigerating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a refrigerating system mounting high pressure doom type compressors of different capacity in which refrigerating machine oil can be returned surely back to respective compressors. SOLUTION: In a refrigerating system comprising a pair of high pressure doom type compressors 1A, 1B of different capacity connected in parallel, delivery piping 47 of the compressors 1A, 1B is provided with an oil separator 36 for separating refrigerating machine oil in delivery gas refrigerant. Separated refrigerating machine oil is returned back to the suction side of the compressors 1A, 1B through an oil return passage 37 provided with an on/off valve 39 being closed when operation of both compressors 1A, 1B is stopped. When both compressors 1A, 1B are operating, refrigerating machine oil separated by the oil separator 36 and refrigerating machine oil in suction gas refrigerant are returned back to the compressors 1A, 1B, respectively, through the oil return passage 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for returning oil to a compressor in a refrigeration system.

[0002]

2. Description of the Related Art In a refrigeration system in which two high-pressure dome-type compressors are connected in parallel, if the capacities of the respective compressors are different, the difference in the dome internal pressure of each of the compressors during the operation of all the units is high. Refrigeration oil at the bottom of the dome is transported from the compressor having a high internal pressure to the compressor having a low internal pressure through a pressure equalizing pipe. If the operation in this state is continued, the refrigerating machine oil of the compressor having a high dome internal pressure continues to move toward the compressor having a low dome internal pressure, and may eventually disappear.

[0003] In the case of a high-pressure dome type compressor, the internal pressure of the compressor during operation increases, so that the refrigerating machine oil gradually accumulates in the compressor during operation stoppage, and the running compressor oil becomes insufficient. This causes a problem that the operation is performed.

[0004] As a method of solving the above-mentioned problems, there is a method of alternately operating the compressors at regular time intervals to secure a refrigerating machine oil amount in each compressor (ie, oil leveling operation control). .

[0005]

However, when the oil equalizing operation control described above is performed, all the units cannot be operated for a certain period of time, and the required capacity of the refrigeration system may not be obtained. .

The present invention has been made in view of the above points, and in a refrigeration system equipped with high-pressure dome type compressors having different capacities, it is ensured that the refrigerating machine oil is returned to each compressor. It is intended to be able to do so.

[0007]

According to the first aspect of the present invention, as a means for solving the above problems, a pair of high pressure dome type compressors 1A and 1B connected in parallel with each other and having different capacities are provided. , Four-way switching valve 2, heat source side heat exchanger 3,
A refrigerant circuit A in which a pressure reducing mechanism 4 and a use-side heat exchanger 5 are sequentially connected via a refrigerant pipe;
In a refrigeration system in which the compressors 1B communicate with each other via an oil equalizing pipe 48, discharge pipes 47 of the compressors 1A and 1B
An oil separator 36 for separating the refrigerating machine oil in the discharged gas refrigerant is provided, and an oil return passage 37 for returning the refrigerating machine oil separated in the oil separator 36 to the suction sides of the compressors 1A and 1B is provided. The oil return passage 37 has the compressor 1
An on-off valve 39 which is closed when both A and 1B are stopped is provided.

With the above-described structure, when both of the compressors 1A and 1B are operating, the oil separator 36
The refrigerating machine oil and the refrigerating machine oil in the suction gas refrigerant separated by the above are returned to the compressors 1A and 1B via the oil return passage 37, respectively. At that time, a large amount of refrigerating machine oil is returned to the compressor with the larger capacity, but since the internal pressure of the compressor with the larger capacity is higher, it is evenly distributed to the compressor with the smaller capacity. The refrigerating machine oil moves through the oil pipe 48, so that the oil is reliably returned to both the compressors 1A and 1B. Therefore, the refrigerating machine oil of the compressors 1A and 1B can be secured without performing the oil equalizing operation control for alternately operating the compressors as in the related art. Moreover, the compressor 1A,
When both 1B are stopped, the on-off valve 39 is closed and the oil return passage 37 is in a non-communication state.
When the operation is stopped, the refrigerant does not flow from the oil separator 36 to the suction side.

According to a second aspect of the present invention, as a means for solving the above-mentioned problems, a pair of high pressure dome type compressors 1A, 1 connected in parallel with each other and having different capacities are provided.
B, a four-way switching valve 2, a heat source side heat exchanger 3, a pressure reducing mechanism 4, and a use side heat exchanger 5 are sequentially connected via a refrigerant pipe to a refrigerant circuit A, and the compressors 1A and 1B are equalized. Oil pipe 4
In the refrigeration system, which is connected to each other via the compressor 8, an oil separator 36 for separating refrigeration oil in the discharge gas refrigerant is provided in the discharge pipe 47 of the compressors 1 </ b> A and 1 </ b> B. The oil return passages 37A, 37B for returning the refrigerating machine oil separated in the above to the respective suction sides of the compressors 1A, 1B are provided, and the oil return passages 37A, 37B are provided.
B is provided with on-off valves 39A and 39B which are closed when the compressors 1A and 1B are both stopped.

With the above configuration, when both the compressors 1A and 1B are operating, the oil separator 36
The refrigerating machine oil and the refrigerating machine oil in the suction gas refrigerant separated by the compressors 1A and 1B are passed through oil return passages 37A and 37B.
B. At that time, a large amount of refrigerating machine oil is returned to the compressor with the larger capacity, but since the internal pressure of the compressor with the larger capacity is higher, it is evenly distributed to the compressor with the smaller capacity. The refrigerating machine oil moves through the oil pipe 48, so that the oil is reliably returned to both the compressors 1A and 1B. Therefore, the compressor 1 does not need to perform the oil equalizing operation control for alternately operating the compressor as in the related art.
A, 1B refrigerating machine oil can be secured. Moreover,
When both the compressors 1A and 1B are stopped, the on-off valves 39A and 39B are closed and the oil return passage 37 is closed.
Since A and 39B are in a non-communication state, the refrigerant does not flow from the oil separator 36 to the suction side when the operation is stopped.

[0011] As in the invention of claim 3, claim 1
3. In the refrigerating apparatus according to any one of (1) and (2), when an on-off valve 49 that is closed when the operation of one of the compressors 1A and 1B is stopped is provided in the oil equalizing pipe 48, When either one of 1A and 1B is stopped, the on-off valve 49 is closed and the refrigerating machine oil cannot move through the oil equalizing pipe 48, so that the operation is stopped from the operating compressor. The movement of the refrigerating machine oil to the compressor is prohibited, so that the running compressor oil does not run short.

According to a fourth aspect of the present invention, as a means for solving the above-mentioned problems, a pair of high pressure dome type compressors 1A, 1 connected in parallel to each other and having different capacities are provided.
B, a four-way switching valve 2, a heat source side heat exchanger 3, a pressure reducing mechanism 4, and a use side heat exchanger 5 are sequentially connected via a refrigerant pipe to a refrigerant circuit A, and the compressors 1A and 1B are equalized. Oil pipe 4
In the refrigeration system, which is connected to each other via the compressor 8, an oil separator 36 for separating refrigeration oil in the discharge gas refrigerant is provided in the discharge pipe 47 of the compressors 1 </ b> A and 1 </ b> B. The oil return passage 37 for returning the refrigerating machine oil separated in the above to the suction side of the compressors 1A, 1B is provided, and the oil equalizing pipe 48 is closed when one of the compressors 1A, 1B is stopped. Open / close valve 49
Is interposed.

With the above configuration, when both the compressors 1A and 1B are operating, the oil separator 36
The refrigerating machine oil and the refrigerating machine oil in the suction gas refrigerant separated by the above are returned to the compressors 1A and 1B via the oil return passage 37, respectively. At that time, a large amount of refrigerating machine oil is returned to the compressor with the larger capacity, but since the internal pressure of the compressor with the larger capacity is higher, it is evenly distributed to the compressor with the smaller capacity. The refrigerating machine oil moves through the oil pipe 48, so that the oil is reliably returned to both the compressors 1A and 1B. Therefore, the refrigerating machine oil of the compressors 1A and 1B can be secured without performing the oil equalizing operation control for alternately operating the compressors as in the related art. And the compressor 1A,
When one of the compressors 1B is stopped, the on-off valve 49 is closed and the refrigerating machine oil cannot move through the oil equalizing pipe 48. The transfer of the refrigerating machine oil to the machine is prohibited, and the running compressor does not run out of the refrigerating machine oil.

As in the invention of claim 5, in the refrigerating apparatus according to any one of claims 1, 2, 3, and 4, the suction pipe 38 to the compressors 1A, 1B is connected to the compressors 1A, 1B. Are located below the suction ports 50A and 50B of the compressor, the large-capacity compressor is shut down and the small-capacity compressor is in operation. It is possible to prevent the refrigerating machine oil from flowing.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

First Embodiment FIGS. 1 and 2 show a refrigerant piping system of a refrigeration apparatus according to a first embodiment of the present invention.

As shown in FIG. 1, the refrigerating apparatus comprises a pair of compressors 1 connected in parallel and having different capacities.
A, 1B, a four-way switching valve 2, a heat source side heat exchanger 3 provided with an outdoor fan 11, an expansion valve 4 acting as a pressure reducing mechanism, and a use side heat exchanger 5 are sequentially connected via a refrigerant pipe. And the compressor 1 branches off from the downstream side of the expansion valve 4 in the heat pump air conditioning refrigerant circuit A and passes through the evaporator 6 for refrigeration.
A and a cooling refrigerant circuit (in other words, a heat recovery circuit) B connected to the suction side of 1B. Two compressors 1
A and 1B, an air-cooled condenser 2 acting as a heat source side heat exchanger, an expansion valve 3 acting as a pressure reducing mechanism, and a pair of evaporators 4 connected in parallel and acting as a use side heat exchanger.
4 is provided with a refrigerant circuit A constituted by sequentially connecting the refrigerant circuits 4 via refrigerant pipes. Here, the compressor 1A has a capacity of 5HP, the compressor 1B has a capacity of 4HP, and the oil sump of the compressor 1A and the oil sump of the compressor 1B are connected by an oil equalizing pipe 48. .

Between the heat source side heat exchanger 3 and the expansion valve 4, a receiver 7 connected to an outlet side of the heat source side heat exchanger 3 during a cooling operation, and a liquid of the receiver 7. Liquid refrigerant from the phase section is transferred to an external heat medium (for example, outdoor air)
The air-cooled first supercooling heat exchanger 8 which is supercooled by the pressure reducing part of the supercooling liquid refrigerant from the first supercooling heat exchanger 8 is reduced by the temperature-sensitive expansion valve 9. And a second triple cooling type supercooling heat exchanger 9 for further supercooling by the latent heat of vaporization of the gas-liquid mixed refrigerant obtained as described above. The second
The gas refrigerant evaporated and vaporized in the supercooling heat exchanger 9 of
It is supplied to the suction side of the compressors 1A and 1B via the low-pressure gas pipe 12. The temperature-sensitive expansion valve 1
The zero-temperature cylinder 10a is attached to the low-pressure gas pipe 12. Reference numeral 13 denotes an electromagnetic on-off valve that is opened only when a part of the liquid refrigerant is supplied to the second subcooling heat exchanger 9. In the present embodiment, the outdoor fan 1
1 is shared by the use side heat exchanger 3 and the first subcooling heat exchanger 8.

On the inlet side of the receiver 7, a bridge circuit 14 having four check valves 14a to 14d is provided. During the cooling operation, the bridge circuit 14 guides the liquid refrigerant from the heat source side heat exchanger 3 to the receiver 7 and guides the liquid refrigerant from the receiver 7 to the use side heat exchanger 5 after passing through the expansion valve 4 to perform the heating operation. At times, it functions as a flow path switching mechanism that guides the liquid refrigerant from the use side heat exchanger 5 to the receiver 7 and guides the liquid refrigerant from the receiver 7 to the heat source side heat exchanger 3 after passing through the expansion valve 4. Reference numeral 15 denotes a check valve that permits the flow of the liquid refrigerant from the heat source side heat exchanger 3 to the receiver 7 only during the cooling operation, and 16 denotes an open valve that operates during the heating operation to connect the expansion valve 4 to the use side heat exchanger 3. The refrigerant is allowed to flow, and is closed during the heating heat recovery operation, and is closed from the expansion valve 4 to the refrigeration evaporator 6.
This is an electromagnetic on-off valve that allows refrigerant to flow only to the solenoid valve.

The upstream liquid pipe 17 of the refrigeration evaporator 6 in the refrigeration refrigerant circuit B has a refrigeration refrigerant circuit C to be described later.
A plate heat exchanger 19 for exchanging heat with the refrigerant gas discharged from the refrigerating compressor 18 is provided.

The refrigerating refrigerant circuit C includes the refrigerating compressor 18, the plate heat exchanger 19, the temperature-sensitive expansion valve 20,
The refrigeration evaporator 21 and the accumulator 22 are sequentially connected via a refrigerant pipe.

Between the utilization side heat exchanger 5 and the bridge circuit 14, a series circuit 23a of an electromagnetic on-off valve 24 and a check valve 25 permitting refrigerant flow only during the cooling operation, and an electromagnetic on-off valve 26 Reversible flow mechanism 2 including a series circuit 23b of a check valve 27 and a check valve 27 permitting refrigerant flow only during the heating operation.
3 are interposed. Reference numeral 28 denotes a liquid escape capillary tube that bypasses the electromagnetic on-off valve 26.

The refrigeration refrigerant circuit B is provided with a bypass circuit 29 for bypassing the refrigeration evaporator 6. The bypass circuit 29 has an electromagnetic opening / closing operation which is opened only when the operation of the refrigeration evaporator 6 is stopped. A valve 30 is provided. Reference numeral 31 denotes an electromagnetic on / off valve that is closed only when the operation of the refrigerating evaporator 6 is stopped, 32 denotes an electromagnetic on / off valve that is closed only when the operation of the refrigerating evaporator 21 is stopped, and 33 denotes a use side heat exchanger 5. The attached indoor fan, 34 is a refrigeration fan attached to the refrigeration evaporator 6, and 35 is a refrigeration fan attached to the refrigeration evaporator 21.

The discharge pipes 47 of the compressors 1A and 1B have:
An oil separator 36 for separating the lubricating oil contained in the gas refrigerant is provided. The lubricating oil separated by the oil separator 36 is supplied to the suction pipe 3 of the compressors 1A and 1B via an oil return pipe 37.
8 is returned. Reference numeral 39 denotes an electromagnetic on-off valve that is opened when the oil is returned.

In the drawing, reference numeral 40 denotes a pressure sensor which functions as a high pressure detecting means for detecting a high pressure which is a discharge pressure of the compressors 1A and 1B, 41 denotes a room temperature sensor which detects indoor air temperature, and 42 denotes a discharged gas refrigerant. Is a pressure sensor that detects the pressure of the suction gas refrigerant, 44 is an outside air temperature sensor that detects the outside air temperature, and 45 and 46 are closing valves.

In the refrigeration apparatus configured as described above, the following operation and effect can be obtained. (I) Cooling operation At this time, the four-way switching valve 2 is switched as shown by the solid line, the electromagnetic switching valve 13 is opened, the electromagnetic switching valve 16 is closed, the electromagnetic switching valve 24 is opened, and the electromagnetic switching valve 24 is opened. On-off valve 2
6, the electromagnetic on / off valve 30 is closed, the electromagnetic on / off valves 31, 32 are opened, and the electromagnetic on / off valve 39 is opened. In the air conditioning refrigerant circuit A, the compressor 1
After the gas refrigerant discharged from A and 1B is condensed and liquefied in the heat source side heat exchanger 3 acting as a condenser,
The liquid refrigerant is sent to the receiver 7 via the check valve 15 and the bridge circuit 14, and the liquid refrigerant from the liquid phase portion of the receiver 7 is supercooled by heat exchange with outdoor air in the first supercooling heat exchanger 8, When further supercooling is required (that is, when the electromagnetic on-off valve 13 is opened), the supercooled liquid refrigerant from the first supercooled heat exchanger 8 is used for the second supercooled heat exchange. The supercooled liquid refrigerant, which is a part of the supercooled liquid refrigerant, is further supercooled by the latent heat of vaporization of the gas-liquid mixed refrigerant decompressed by the temperature-sensitive expansion valve 10, and decompressed by the expansion valve 4 to the use side heat exchanger 5. It is supplied and evaporated, and the obtained latent heat of evaporation is used as a cooling heat source, and then returned to the compressors 1A and 1B.

In the refrigeration circuit B, the refrigerant decompressed by the expansion valve 4 branches off from the air conditioning refrigerant circuit A and passes through the plate heat exchanger 19 to the refrigeration evaporator 6.
And evaporates, and the obtained latent heat of evaporation is used as a cold heat source for refrigeration, and then returned to the compressors 1A and 1B.

Further, in the refrigeration circuit C, the gas refrigerant discharged from the refrigeration compressor 18 flows through the liquid pipe 17 in the refrigeration circuit B in the plate heat exchanger 19 acting as a condenser. After being condensed and liquefied by heat exchange with the liquid refrigerant, the pressure is reduced by the expansion valve 20 and supplied to the refrigerating evaporator 21 to evaporate. The obtained latent heat of evaporation is used as a refrigerating cold heat source. Is returned to the compressor 18 through the compressor.

When the temperature inside the refrigerator / freezer is high, it is desirable to operate the indoor fan 33 at a low speed in order to prevent drafts in the refrigerator / freezer. (II) Heating operation At this time, the four-way switching valve 2 is switched as shown by the solid line, the electromagnetic switching valve 13 is opened, the electromagnetic switching valve 16 is closed, the electromagnetic switching valve 24 is closed, and the electromagnetic switching valve 24 is closed. On-off valve 2
6 is opened, the electromagnetic on-off valve 30 is closed, the electromagnetic on-off valves 31 and 32 are opened, and the electromagnetic on-off valve 39 is opened. In the air conditioning refrigerant circuit A, the compressor 1
The gas refrigerant discharged from A, 1B is condensed and liquefied in the use side heat exchanger 5 acting as a condenser, and the obtained condensation latent heat is used as a heating heat source.
5 and to the receiver 7 via the bridge circuit 14,
The liquid refrigerant from the liquid phase portion of the receiver 7 is subcooled in the first subcooling heat exchanger 8 by heat exchange with outdoor air, and when further subcooling is required (that is, the electromagnetic on-off valve 1
3 is opened), the supercooled liquid refrigerant from the first subcooled heat exchanger 8 is a part of the supercooled liquid refrigerant in the second subcooled heat exchanger 9. Temperature expansion valve 1
The refrigerant is further supercooled by the latent heat of vaporization of the gas-liquid mixed refrigerant decompressed by 0, decompressed by the expansion valve 4, supplied to the evaporator 6 via the plate heat exchanger 19 in the refrigeration refrigerant circuit B, and evaporated. The latent heat of evaporation is used as a cold heat source for refrigeration, and then returned to the compressors 1A and 1B.

In the refrigeration circuit C, gas refrigerant discharged from the refrigeration compressor 18 flows through the liquid pipe 17 in the refrigeration circuit B in the plate heat exchanger 19 acting as a condenser. After being condensed and liquefied by heat exchange with the liquid refrigerant, the pressure is reduced by the expansion valve 20 and supplied to the refrigerating evaporator 21 to evaporate. The obtained latent heat of evaporation is used as a refrigerating cold heat source.
The refrigerant is returned to the compressor 18 through the line 2.

As described above, in the present embodiment, the evaporator 6 in the refrigeration refrigerant circuit B during the heating operation is used.
Thus, the waste heat used as the cold heat source for refrigeration is recovered in the use-side heat exchanger 5 as the heating heat source. At this time, one of the compressors 1A and 1B has been stopped (in other words, the capacity of the compressor has been reduced).

When the heating load is small (ie, the difference between the set temperature and the room temperature is small), the heat source for refrigeration in the evaporator 6 becomes insufficient, and the four-way switching valve 2 is moved to the cooling operation side. It is preferable to switch to the cooling cycle and open the electromagnetic on-off valve 16 so that the heat source side heat exchanger 3 acts as a condenser. During the operation in the cooling cycle, when the heating load increases (that is, when the difference between the set temperature and the room temperature increases), the four-way switching valve 2 is switched to the heating operation side to perform the heating cycle and perform the electromagnetic switching. The valve 16 may be closed to return to the heating heat recovery operation in which the use side heat exchanger 5 acts as a condenser.

When the refrigeration / refrigeration load is reduced during the heating operation (in other words, when the low pressure which is the suction pressure of the compressors 1A and 1B is reduced), the air volume of the indoor fan 33 is automatically adjusted. And the use side heat exchanger 5
And the evaporator 6 can be balanced.

Further, when the refrigeration / refrigeration load is reduced during the heating operation (in other words, the low pressure which is the suction pressure of the compressors 1A and 1B is reduced), the use-side heat exchanger 5 Since the heating heat source becomes insufficient, it is preferable that the electromagnetic on-off valve 16 be opened to operate the heat source side heat exchanger 3 as an evaporator.

Further, even when the driving of the indoor fan 33 is stopped (ie, when the operation of the use-side heat exchanger 5 is stopped), if the room temperature is equal to or lower than a predetermined value, the four-way switching valve 2 is moved to the heating operation side. The heating and heat recovery operation may be automatically performed by switching the operation and closing the electromagnetic on-off valve 16.

By the way, in the present embodiment, FIG.
As shown in the figure, the suction pipe 38 is connected to the compressor 1A, 1A.
B, and is located below the suction ports 50A and 50B of B. The oil return passage 37 is located near the suction port 50A of the compressor 1A (that is, the compressor with the larger capacity) in the suction pipe 38. It is connected. The oil equalizing pipe 48 is provided with an electromagnetic opening / closing valve 49 that is closed when one of the compressors 1A and 1B is stopped. Reference numeral 51 denotes a filter.

The compressors 1A and 1B, the solenoid on-off valve 39,
49 is to be turned ON / OFF as shown in FIG. In FIG. 3, ○ indicates open, and × indicates closed.

With the above configuration, when both of the compressors 1A and 1B are operating, the solenoid on-off valve 3
9 and 49 are both opened, and the refrigerating machine oil F separated by the oil separator 36 is supplied through the oil return passage 37 to the suction pipe 3.
8 together with the refrigerating machine oil F in the suction gas refrigerant, and is returned to the compressors 1A and 1B in accordance with the suction pressure. At that time, a large amount of the refrigerating machine oil F is returned to the compressor having the larger capacity. However, since the internal pressure of the compressor having the larger capacity is higher, the compressor F having the smaller capacity is returned to the compressor having the smaller capacity. The refrigerating machine oil F moves through the oil equalizing pipe 48, and the oil is reliably returned to both the compressors 1A and 1B. Therefore, the refrigerating machine oil F of the compressors 1A and 1B can be secured without performing the oil equalizing operation control for alternately operating the compressor as in the related art.

In addition, when both the compressors 1A and 1B are stopped, the on-off valve 39 is closed and the oil return passage 37 is not in communication. The refrigerant does not flow to

Further, when one of the compressors 1A and 1B is stopped, the on-off valve 49 is closed and the refrigerating machine oil F cannot be moved through the oil equalizing pipe 48. The movement of the refrigerating machine oil F from the compressor in operation to the compressor in suspension of operation is prohibited, and the compressor oil F in the operating compressor does not run short.

Furthermore, since the suction pipes 38 to the compressors 1A and 1B are located below the suction ports 50A and 50B of the compressors 1A and 1B, the operation of the compressor having a large capacity is stopped and the capacity of the compressor is reduced. When the small compressor is operating, it is possible to prevent the refrigerating machine oil F from flowing into the larger compressor through the suction pipe 38.

Second Embodiment FIG. 4 shows a suction pipe portion in a refrigeration apparatus according to a second embodiment of the present invention.

In this case, the refrigerating machine oil F separated in the oil separator 36 is supplied to the suction ports 50A, 50A of the compressors 1A, 1B.
The oil return passages 37A and 37B are connected near the suction ports 50A and 50B so as to surely return the oil return to 0B. The oil return passages 37A, 37B have opening / closing valves 39A, 3 which are closed when the compressors 1A, 1B are both stopped.
9B are interposed. In this way, when both the compressors 1A and 1B are operating, the refrigerating machine oil separated by the oil separator 36 and the refrigerating machine oil in the suction gas refrigerant are supplied to the compressor 1 via the oil return passages 37A and 37B.
A and 1B are returned respectively, and more reliable oil return is obtained. The other configuration and operation and effect are the same as those in the first embodiment, and thus the description is omitted.

[0044]

According to the first aspect of the present invention, a pair of high pressure dome type compressors 1A and 1B, four-way switching valves 2, and heat source side heat exchangers connected in parallel and having different capacities are provided. 3, a refrigerant circuit A in which a pressure reducing mechanism 4 and a use-side heat exchanger 5 are sequentially connected via a refrigerant pipe;
A and 1B are connected to each other through an oil equalizing pipe 48. In the refrigerating apparatus, a discharge pipe 47 of the compressors 1A and 1B is used.
And an oil separator 36 for separating refrigeration oil in the discharged gas refrigerant.
And an oil return passage 37 for returning the refrigerating machine oil separated in the oil separator 36 to the suction side of the compressors 1A and 1B is provided, and the oil return passage 37 is provided with the compressors 1A and 1B. When the compressors 1A and 1B are operated together, the refrigerating machine oil and the suction gas refrigerant separated by the oil separator 36 are provided via an on-off valve 39 which is closed when both are stopped. Since the refrigerating machine oil is returned to the compressors 1A and 1B via the oil return passage 37, a large amount of refrigerating machine oil is returned to the larger capacity compressor, but the larger capacity is used. Since the internal pressure of the compressor is higher, the oil equalizing pipe 4 is connected to the compressor of smaller capacity.
8, the refrigerating machine oil moves, and the oil is reliably returned to both compressors 1A and 1B. Thus, even if the oil equalizing operation control for alternately operating the compressors is not performed as in the related art,
There is an effect that refrigerating machine oil for the compressors 1A and 1B can be secured. In addition, when both the compressors 1A and 1B are stopped, the on-off valve 39 is closed and the oil return passage 37 is in a non-communication state. Therefore, when the operation is stopped, the refrigerant flows from the oil separator 36 to the suction side. There is also an effect that it stops flowing.

According to the second aspect of the present invention, as a means for solving the above problems, a pair of high pressure dome type compressors 1A, 1A connected in parallel and having different capacities are provided.
B, a four-way switching valve 2, a heat source side heat exchanger 3, a pressure reducing mechanism 4, and a use side heat exchanger 5 are sequentially connected via a refrigerant pipe to a refrigerant circuit A, and the compressors 1A and 1B are equalized. Oil pipe 4
In the refrigeration system, which is connected to each other via the compressor 8, an oil separator 36 for separating refrigeration oil in the discharge gas refrigerant is provided in the discharge pipe 47 of the compressors 1 </ b> A and 1 </ b> B. The oil return passages 37A, 37B for returning the refrigerating machine oil separated in the above to the respective suction sides of the compressors 1A, 1B are provided, and the oil return passages 37A, 37B are provided.
B is provided with on-off valves 39A and 39B that are closed when the compressors 1A and 1B are both stopped, and when the compressors 1A and 1B are both operated,
Since the refrigerating machine oil separated by the oil separator 36 and the refrigerating machine oil in the suction gas refrigerant are returned to the compressors 1A and 1B via the oil return passages 37A and 37B, respectively, the larger capacity compressor is used. A large amount of refrigerating machine oil is returned to the compressor, but since the internal pressure of the larger capacity compressor is higher, the refrigerating machine oil moves to the smaller capacity compressor via the oil equalizing pipe 48. This means that both compressors 1A, 1
B can be reliably returned to the compressor 1 without performing the oil leveling operation control for alternately operating the compressor as in the related art.
There is an effect that the refrigerating machine oil of A and 1B can be secured. Moreover, when both the compressors 1A and 1B are stopped, the on-off valves 39A and 39B are closed, and
Since the oil return passages 37A and 39B are in a non-communication state, there is also an effect that the refrigerant does not flow from the oil separator 36 to the suction side when the operation is stopped.

As in the invention of claim 3, claim 1
3. In the refrigerating apparatus according to any one of (1) and (2), when an on-off valve 49 that is closed when the operation of one of the compressors 1A and 1B is stopped is provided in the oil equalizing pipe 48, When either one of 1A and 1B is stopped, the on-off valve 49 is closed and the refrigerating machine oil cannot move through the oil equalizing pipe 48, so that the operation is stopped from the operating compressor. The movement of the refrigerating machine oil to the compressor is prohibited, so that the running compressor oil does not run short.

According to the fourth aspect of the present invention, a pair of high pressure dome type compressors 1A, 1B, four-way switching valve 2, heat source side heat exchanger 3, The compressor 1 includes a refrigerant circuit A in which a pressure reducing mechanism 4 and a use-side heat exchanger 5 are sequentially connected through a refrigerant pipe.
A and 1B are connected to each other through an oil equalizing pipe 48. In the refrigerating apparatus, a discharge pipe 47 of the compressors 1A and 1B is used.
And an oil separator 36 for separating refrigeration oil in the discharged gas refrigerant.
And an oil return passage 37 for returning the refrigerating machine oil separated in the oil separator 36 to the suction side of the compressors 1A and 1B is provided, and the oil equalizing pipe 48 is provided with the compressors 1A and 1B. When both of the compressors 1A and 1B are operating, an on-off valve 49 that is closed when one of the operation is stopped is interposed. Oil in the oil return passage 3
7, a large amount of the refrigerating machine oil is returned to the compressor having the larger capacity, but the internal pressure of the compressor having the larger capacity is reduced. Therefore, the refrigerating machine oil moves to the compressor having the smaller capacity via the oil equalizing pipe 48, so that the oil is reliably returned to both the compressors 1A and 1B. There is an effect that the refrigerating machine oil of the compressors 1A and 1B can be secured without performing the oil equalizing operation control for alternately operating the compressors. Moreover, when one of the compressors 1A and 1B is stopped, the on-off valve 4
9 is closed and the refrigerating machine oil cannot be moved through the oil equalizing pipe 48, so that the movement of the refrigerating machine oil from the compressor in operation to the compressor in non-operation is prohibited. There is also an effect that a shortage of refrigerating machine oil in the compressor does not occur.

As in the invention of claim 5, in the refrigerating apparatus according to any one of claims 1, 2 and 3, the suction pipe 38 to the compressors 1A and 1B is connected to the compressor 1
When the compressor with the larger capacity is shut down and the compressor with the smaller capacity is operated when the compressor with the larger capacity is located below the suction ports 50A and 50B of A and 1B, the larger capacity is set via the suction pipe 38. Refrigeration oil can be prevented from flowing into the compressor.

[Brief description of the drawings]

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

FIG. 2 is a piping system diagram showing a structure of a suction pipe portion in the refrigeration apparatus according to the first embodiment of the present invention.

FIG. 3 is a table illustrating operation states of a compressor and an electromagnetic on-off valve in the refrigeration apparatus according to the first embodiment of the present invention.

FIG. 4 is a piping diagram showing a structure of a suction pipe part in a refrigeration apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

1A and 1B are compressors, 2 is a four-way switching valve, 3 is a heat source side heat exchanger, 4 is a pressure reducing mechanism (expansion valve), 5 is a use side heat exchanger,
36 is an oil separator, 37, 37A and 37B are oil return passages,
38 is a suction pipe, 39, 39A and 39B are on-off valves (electromagnetic on-off valves), 48 is an oil equalizing pipe, 49 is an on-off valve (electromagnetic on-off valve),
50A and 50B are suction ports.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuhide Nomura 1304 Kanaokacho, Sakai-shi, Osaka Daikin Industries Inside Kanaoka Plant of Sakai Seisakusho Co., Ltd. (72) Masaaki Takegami 1304 Kanaokacho, Sakai-shi, Osaka Daikin Industries Inside the Sakai Seisakusho Kanaoka Plant (72) Inventor Akitoshi Ueno 1304 Kanaokacho, Sakai-shi, Osaka Daikin Industries Sakai Seisakusho Kanaoka Plant

Claims (5)

[Claims] 1. A pair of high pressure dome type compressors (1A), (1) connected in parallel with each other and having different capacities.
B), a refrigerant circuit (A) in which the four-way switching valve (2), the heat source side heat exchanger (3), the pressure reducing mechanism (4), and the use side heat exchanger (5) are sequentially connected via a refrigerant pipe. A refrigerating apparatus comprising the compressors (1A) and (1B) communicating with each other via an oil equalizing pipe (48).
An oil separator (36) for separating the refrigerating machine oil in the discharged gas refrigerant is disposed in the discharge pipe (47) of (A), (1B), and the refrigerating machine oil separated in the oil separator (36) is provided. An oil return passage (37) for returning the oil to the suction side of the compressors (1A) and (1B) is provided, and both the compressors (1A) and (1B) stop operating in the oil return passage (37). A refrigeration system characterized by interposing an on-off valve (39) that is closed when the operation is performed. 2. A pair of high pressure dome type compressors (1A), (1) connected in parallel with each other and having different capacities.
B), a refrigerant circuit (A) in which the four-way switching valve (2), the heat source side heat exchanger (3), the pressure reducing mechanism (4), and the use side heat exchanger (5) are sequentially connected via a refrigerant pipe. A refrigerating apparatus comprising the compressors (1A) and (1B) communicating with each other via an oil equalizing pipe (48).
An oil separator (36) for separating the refrigerating machine oil in the discharged gas refrigerant is disposed in the discharge pipe (47) of (A), (1B), and the refrigerating machine oil separated in the oil separator (36) is provided. Oil return passages (37A) and (37B) for returning the oil to the respective suction sides of the compressors (1A) and (1B), and the oil return passages (37A) and (37B) are provided with the compressor ( A refrigerating apparatus characterized in that on-off valves (39A) and (39B) that are closed when both of 1A) and (1B) are stopped are provided. 3. The oil equalizing pipe (48) is provided with an on-off valve (49) that is closed when the operation of one of the compressors (1A) and (1B) is stopped. The refrigeration apparatus according to any one of claims 1 and 2, wherein 4. A pair of high pressure dome type compressors (1A), (1A) connected in parallel with each other and having different capacities.
B), a refrigerant circuit (A) in which the four-way switching valve (2), the heat source side heat exchanger (3), the pressure reducing mechanism (4), and the use side heat exchanger (5) are sequentially connected via a refrigerant pipe. A refrigerating apparatus comprising the compressors (1A) and (1B) communicating with each other via an oil equalizing pipe (48).
An oil separator (36) for separating the refrigerating machine oil in the discharged gas refrigerant is disposed in the discharge pipe (47) of (A), (1B), and the refrigerating machine oil separated in the oil separator (36) is provided. Oil return passage (37) for returning the oil to the suction side of the compressors (1A) and (1B), and the oil equalizing pipe (4
8) A refrigerating apparatus characterized in that an on-off valve (49) that is closed when one of the compressors (1A) and (1B) is stopped is provided. 5. A suction pipe (38) for the compressors (1A) and (1B) is connected to a suction port (5) of the compressors (1A) and (1B).
The refrigeration apparatus according to any one of claims 1, 2, 3 and 4, wherein the refrigeration apparatus is located below the first and second parts (0A) and (50B).