JPH04320763A - Freezer - Google Patents

Abstract

PURPOSE:To prevent any unbalanced state from being generated in an amount of oil in compressors disposed in parallel to each other. CONSTITUTION:Each of a plurality of compressors 111 and 112 is provided with oil separators 121 and 122. Return pipes 211 and 212 for returning separated oil to each of the compressors 111 and 112 are connected to these oil separators 121 and 122. The return pipes 211 and 212 are connected to each other by a connection pipe 23. The connection pipe 23 and/or return pipes 211 and 212 are provided with valves 251, 252, 271 and 272 for use in guiding a part of oil discharged from the compressors being operated to a compressor being stopped in the case that an amount of oil in the compressor being stopped is less than a predetermined value.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system having compressors arranged in parallel.

0002

[Prior Art] Generally, a plurality of indoor heat exchangers (indoor units) are arranged in parallel, and a plurality of compressors are arranged in parallel with refrigerant pipes connected to each indoor heat exchanger. A multi-type air conditioner for buildings is known (for example, see Japanese Patent Laid-Open No. 2-85656). This type of multi-type air conditioner has the advantage that it can be integrated into a large-capacity system.

0003

[Problems to be Solved by the Invention] However, in the conventional configuration, since a plurality of compressors are arranged in parallel, there is a drawback that an imbalance occurs in the amount of lubricating oil (hereinafter referred to as oil) in each compressor. There is. For example, if one compressor is stopped due to a temporary drop in the cooling or heating load, the oil already discharged from the stopped compressor will be transferred to the other operating compressor. Since the oil is collected, there is a problem in that while the amount of oil in the compressor during operation increases, the amount of oil in the compressor when it is stopped decreases.

[0004] After that, when the load increases, the stopped compressor is restarted, but in this case, due to the reasons mentioned above, the oil amount in the restarted compressor becomes lower than the appropriate value. As a result, there is a problem in that the components within the compressor progress to wear and the life of the air conditioner is shortened.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a refrigeration system which solves the problems of the above-mentioned conventional techniques and prevents the oil amount in the compressors arranged in parallel from becoming unbalanced. be.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention connects a plurality of compressors in parallel, provides an oil separator for each of the plurality of compressors, and In a refrigeration system in which a return pipe for returning the separated oil to each compressor is connected to the separator, and the operation of these compressors is controlled simultaneously or individually according to the load, the return pipes are connected to each other by a connecting pipe. If the oil level of the stopped compressor falls below a predetermined value, the connection pipe and/or return pipe will be connected to the
The compressor is characterized by being provided with a valve for guiding a portion of the oil discharged from the operating compressor to the stopped compressor.

[0007]

[Operation] According to the present invention, when the amount of oil in the stopped compressor drops below a predetermined value, the valves installed in the connecting pipe and/or the return pipe are opened, and the oil is removed from the operating compressor. A portion of the discharged oil is guided to the stopped compressor, and the amount of oil in the stopped compressor is maintained at a constant level.Then, the load increases and the stopped compressor is restarted. Even in the case where the vehicle is operated, the operating state can be resumed smoothly.

[0008]

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, 11 and 12 indicate outdoor units, and 31 and 32 indicate indoor units. The outdoor unit 11 includes an accumulator 101
, a scroll or reciprocating compressor 111 , an oil separator 121 , a four-way valve 131 , and an outdoor heat exchanger 1
41, electric expansion valve 151, and receiver tank 1
It consists of 61. The outdoor unit 12 is the same as the outdoor unit 11, so a description thereof will be omitted. The indoor unit 31 is an indoor heat exchanger 341
and an electric expansion valve 351. The indoor unit 32 is the same as the indoor unit 31, so a description thereof will be omitted. These are connected via pipes 5 and 7 to constitute a refrigeration cycle.

Next, the oil return circuit of the outdoor unit 11 will be explained.

The refrigerant and oil discharged from the compressor 111 are separated by an oil separator 121, and the oil separated here is returned to the scroll or reciprocating compressor 111 through a return pipe 211. Here, since the scroll or reciprocating type compressor 111 is an internal low pressure type compressor, the return pipe 211 is directly connected to the compressor 111. The outdoor unit 12 is the same as the outdoor unit 11, so a description thereof will be omitted.

According to this embodiment, the return pipe 211 of the outdoor unit 11 and the return pipe 212 of the outdoor unit 12 are connected by the connecting pipe 23, and the connecting pipe 23 has valves 251, 252 is incorporated, and valves 271 and 272 are incorporated in the above-mentioned return pipe 211 and return pipe 212.

[0013] Here, the valves 251 and 252 are opened and closed, and among these valves 251 and 252, the valve 251
Even when the valve 252 is fully closed, it cannot prevent the flow of oil from right to left in the figure, and even when the valve 252 is fully closed, it cannot prevent the flow of oil from left to right in the figure. In this way, the valve 251
, 252 were used in outdoor unit 11.
, 12 can be used for multiple purposes. In addition, the valve 251,
Two 252 are not necessarily required, but if you use an on-off valve that completely blocks flow in both directions when fully closed,
It may be one piece.

These valves 251, 252, and valve 27
1,272 is controlled to close when the operation of the outdoor unit 11 is stopped and to open when it starts. Valves 251, 252, and valves 271, 27
2 are connected to controllers 281 and 282, and these controllers 281 and 282 are connected to the compressor 1.
Sensors 291 and 292 that operate when the oil level drops to the extent that 11 and 112 cannot operate normally.
is connected.

Next, the operation of this embodiment will be explained.

When the four-way valves 131 and 132 are switched as shown by the solid lines in FIG. 1, the refrigerant flows as shown by the arrows in the figure. The electric expansion valves 151 and 152 are substantially fully open, and the opening degree of the electric expansion valves 351 and 352 is adjusted according to the load. In this case, two outdoor units 11
, 12 are operated simultaneously, and the outdoor heat exchangers 141 , 1
42 acts as a condenser, and indoor heat exchangers 341,
342 acts as an evaporator. That is, cold air is sent out from the indoor heat exchangers 341 and 342, and a high-load cooling operation is performed.

When the four-way valves 131 and 132 are switched as shown by the dotted lines in FIG. 1, the refrigerant flows in the direction opposite to the arrow in the figure. The opening degree of the electric expansion valves 151 , 152 and the electric expansion valves 351 , 352 is adjusted according to the load. In this case, the two outdoor units 11 and 12 are operated simultaneously, the two outdoor heat exchangers 141 and 142 act as evaporators, and the indoor heat exchangers 341 and 342 act as condensers. That is, the indoor heat exchangers 341, 3
Warm air is sent out from 42, and high-load heating operation is performed.

[0018] When in either of these cooling or heating operating states, as described above, the valves 251 and 252 are closed.
, and valves 271 and 272 are in the open state, the oil separated by the oil separators 121 and 122 is
As shown by dotted lines in the figure, return pipes 211 and 212
Through the scroll or reciprocating compressor 111
, 112. In this case, the return pipe 211
, 212 as well as the connecting pipe 23 are in communication, so the amount of oil between the compressors 111 and 112 is balanced.

By the way, if, for example, one of the compressors 112 stops due to a temporary decrease in the cooling or heating load, the valves 252 and 272 will be closed as described above. In this state, the oil already discharged from the stopped compressor 112 is collected by the other operating compressor 111.

According to this embodiment, as shown in FIG. 2, when the amount of oil in the stopped compressor 112 drops below a predetermined amount, the sensor 292 is activated and the controller 282 is activated. is activated and valves 252 and 272 are opened, so that oil is collected into the stopped compressor 112 through the connecting pipe 23, as shown by dotted lines in the figure. On the other hand, if the amount of oil in the stopped compressor 112 reaches a predetermined amount or more, the sensor 2
92 is activated, controller 282 is activated, valves 252 and 272 are closed, and oil recovery is stopped.

According to this, since the amount of oil in the stopped compressor 112 is maintained at a constant level, even when the load increases and the stopped compressor 112 restarts operation, The operating state can be started smoothly.

FIG. 3 shows another embodiment.

As mentioned above, in FIG.
, 112 use internal low-pressure scroll or reciprocating type compressors, but in FIG.
112 uses an internal high-pressure rotary compressor.

Since the compressors 111 and 112 of this type are of internal high pressure type, oil is directly supplied to the compressor 111 during operation.
, 112 cannot be returned. For that purpose, usually
Return pipes 511 , 512 are provided in the suction lines of the compressors 111 , 112 .
512 to return operating oil to the compressor.

According to this embodiment, in addition to the return pipes 511 and 512, the compressors 111 and 112
A return pipe 211 and a return pipe 212 are provided for returning oil to the compressors 111 and 112 while the compressor is stopped, and these return pipes 211 and 212 are connected to the connecting pipe 2.
Connected by 3. Valves 251 and 252 are incorporated into this connecting pipe 23, and the above-mentioned return pipe 21
1 and the return pipe 212 have valves 271 and 272 incorporated therein. The other configurations are substantially the same as those in FIG.

With this structure, oil during operation is returned to the suction line of the compressor through the return pipes 511 and 512. Further, during the stoppage, the valve 252 (or valve 251 ) is opened, and the compressor 112 (or compressor 111
), the oil amount between these compressors 111 and 112 connected in parallel is reliably balanced.

[0027]

As is clear from the above description, according to the present invention, the return pipes are connected to each other by a connecting pipe, and the oil amount of the compressor during the stoppage is maintained at a predetermined value in the connecting pipe and/or the return pipe. We have installed a valve to direct some of the oil discharged from the operating compressor to the stopped compressor in the following cases, so even if one compressor stops, the operating Since part of the oil from the other compressor is guided, the oil amount between the compressors can be kept balanced. Therefore, it is possible to prevent the oil amount of the compressor from decreasing while the compressor is stopped.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of a refrigeration system according to the present invention.

FIG. 2 is a system diagram showing the same refrigeration system.

FIG. 3 is a system diagram showing another embodiment.

[Explanation of symbols]

11 , 12 Outdoor units 31 , 32 Indoor units 101 , 102 Accumulators 111 , 1
12 Compressors 121, 122 Oil separators 141, 142 Outdoor heat exchangers 211, 212 Return pipes 23 Connecting pipes 251, 252 Valve 271, 272 Valve 281, 282 Controller 291, 292 Sensor

Claims (1)

[Claims] Claim 1: A plurality of compressors are connected in parallel, and each of the plurality of compressors is provided with an oil separator, and each of the oil separators is provided with a return valve for returning separated oil to each compressor. In a refrigeration system in which pipes are connected and the operation of these compressors is controlled simultaneously and individually according to the load, the return pipes are connected by a connecting pipe, and the connecting pipe and/or the return pipe is connected to the A refrigeration system characterized by being provided with a valve for guiding a part of the oil discharged from the operating compressor to the stopped compressor when the oil amount in the compressor falls below a predetermined value. Device.