JPH04320764A - Freezer device - Google Patents

Abstract

PURPOSE:To prevent any unbalanced state from being generated in an amount of oil during an operation of each of 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 connecting pipe 23, the connecting pipe 23 and/or return pipes 211 and 212 are provided with valves 251 and 252. Oil level sensors 291 and 292 for use in controlling an opening or closing of each of the valves 251 and 252 are fixed to the compressors 111 and 112 while their heights being varied.

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. That is, since oil discharged from a plurality of compressors circulates within the same refrigerant circuit and returns to each compressor, during operation, the amount of oil returned to each compressor becomes uneven. There is a problem that an imbalance occurs in the amount of oil in the compressor.

[0004] When the amount of oil in the compressor becomes less than an appropriate value, there is a problem that the wear of the members in the compressor progresses 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 eliminates the problems of the above-mentioned conventional technology and prevents the oil amount from becoming unbalanced during operation in compressors arranged in parallel. It's about doing.

[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. A valve is provided in the connecting pipe and/or the return pipe, and a plurality of oil level detectors for controlling the opening and closing of the valve are attached to the compressor at different heights.

[0007]

[Operation] According to the present invention, a plurality of oil level detectors for controlling the opening and closing of the valves are installed on the compressor at different heights, so that the oil level during operation of the compressor is at least at a high level or higher. , it is possible to judge whether the oil level is below the low level, and based on the result of this judgment, the valves are finely controlled to open and close, making it possible to finely control the oil amount and balance the oil amount between multiple compressors. It can be maintained properly.

[0008]

Embodiment An embodiment of the present invention will be described below with reference to FIG.

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 into the above-mentioned return pipe 211 and return pipe 212,
Valves 271 and 272 are incorporated.

[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 are connected to controllers 281 and 282, and these controllers 281 and 282 are connected to
Oil level detectors 291 and 292 are connected. As shown in FIG. 2, the oil level detector 292 includes a high level sensor a and a low level sensor b, and these sensors a and b are attached to the compressor 112 at different heights. The oil level detector 291 is the same as the oil level detector 292, so a description thereof will be omitted.

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.

During these cooling or heating operations, the oil separated by the oil separators 121 and 122 passes through return pipes 211 and 212 and is compressed in a scroll or reciprocating type, as shown by dotted lines in FIGS. 1 and 2. Machine 111,1
Returned to 12.

The oil recovery process during this operation is controlled via controllers 281 and 282.
It is controlled as follows.

Referring to FIGS. 3 and 4, compressor 112
During operation (step 1), it is determined whether the oil amount is in zone C below low level sensor b or in zones A and B above low level sensor b (step 2). When it is determined that the sensor is in the upper zones A and B, it is then determined whether the sensor is in the lower zone B or in the upper zone A than the high level sensor a (step 3), and it is determined that the sensor is in the upper zone A. After a certain period of time has passed (step 4), the valve 272 is closed (step 5), and the oil separated by the oil separator 122 is removed from the compressor 1.
Stop returning to 12. In this case, this compressor 1
12 is sent to another operating compressor 111. When it is determined that the level is in zone B below the high level sensor a, after a certain period of time has elapsed (step 6), the valve 272 is opened (step 7), and the oil separated by the oil separator 122 is sent to the own compressor 112. return.

In addition, in step 2, the operation of the compressor 112 is stopped (step 8), and the operation of the compressor 112 is stopped (step 8).
At the same time, the valve 252 shown in FIG. 1 is opened. Here, the reason why the compressor 112 is stopped is because when the amount of oil in the compressor 112 becomes less than an appropriate value, the wear of the members in the compressor 112 progresses. In this state, since the compressor 112 is stopped, the operation of the oil separator 122 is also stopped. In this case, as shown in FIG. 1, oil is recovered from the other operating compressor 111 through the connecting pipe 23.

According to this embodiment, the amount of oil in the compressor 112 can be reliably maintained within the appropriate B zone by repeating the above process. Note that the compressor 111 is the same as the compressor 112, so a description thereof will be omitted.

FIG. 5 shows another embodiment.

As mentioned above, in FIG.
, 112 use internal low-pressure scroll or reciprocating type compressors; however, in FIG.
112 uses an internal high-pressure rotary compressor. This type of compressor 112 is of internal high pressure type, so
During operation, oil cannot be returned directly to the compressor 112. For this purpose, a return pipe 512 is normally provided in the suction line of the compressor 112, and this return pipe 51
A valve 532 is provided in the middle of the compressor 112, and oil during operation is returned to the compressor 112 through this valve 532.

To explain the operation of this embodiment, the controller 282 operates the valve 532 through the same process as described above.
is controlled to return operating oil into the suction line of the compressor 112. Further, when the compressor 112 is stopped during the above process, the valve 272 is opened and the oil from the compressor 111 which is in operation is recovered through the connecting pipe 23. Valve 272 is normally closed. According to this, the amount of oil in the compressor 112 can be reliably maintained within an appropriate range. Note that the compressor 111 is the same as the compressor 112, so a description thereof will be omitted.

FIG. 6 shows another embodiment.

The oil level detector 712 includes a high level sensor a, a low level sensor b, and an intermediate level sensor c in between. It has been installed with a change. The oil level detector 711 is the same as the oil level detector 712, so a description thereof will be omitted.

The operation of this embodiment will be explained with reference to FIG. 7. First, the control in the A zone and the C zone is as follows.
This is the same control as shown in FIGS. 3 and 4. In the detection zone of medium level sensor c located between high level sensor a and low level sensor b, there are three zones B1, B2, and B.
It is controlled separately in 3 parts.

[0029] The oil amount in the compressor 112 is in the upper zone B1.
, the oil amount in the compressor 112 tends to increase. In this case, it is determined whether the oil amount in the other operating compressor 111 is in zone C or zone B3, and when it is in either zone, the valve 272 is closed and the oil separator 122 is The separated oil is transferred to another compressor 111.
Send to. The amount of oil in the compressor 111 during other operation is
If not in zone C or zone B3, valve 272
is opened, and the oil separated by the oil separator 122 is returned to its own compressor 112. Furthermore, when the oil amount in the compressor 112 is in the upper zone B2, the oil amount in the compressor 112 is on a downward trend. In this case, the valve 272 is opened regardless of the amount of oil in the other operating compressors 111, and the oil separated by the oil separator 122 is transferred to the own compressor 111.
Return to Further, if it is determined that the oil is in the lower zone B3 of the middle level sensor c, the valve 272 is opened to return oil to the compressor 112.

According to this, by repeating the above process, the amount of oil in the compressor 112 is reliably maintained within the appropriate zones B1, B2, and B3. In addition,
The compressor 111 is the same as the compressor 112, so a description thereof will be omitted.

FIG. 8 shows another embodiment.

As mentioned above, in FIG.
, 112 use internal low-pressure scroll or reciprocating type compressors; however, in FIG.
112 uses an internal high-pressure rotary compressor. Since this type of compressor 111 , 112 is of internal high pressure type, oil is directly supplied to the compressor 111 , 11 during operation.
I can't go back to 2. For this purpose, a return pipe 5 is usually provided in the suction line of the compressors 111 and 112.
11 and 512 are provided, and these return pipes 511 and 512 are provided.
The oil during operation is returned to the compressor through the compressor.

To explain the operation of this embodiment, the controller 282 is operated through almost the same process as the embodiment of FIG.
The valve 532 is controlled by the
Return it to the suction line of 2. In addition, when the compressor 112 is stopped during the above process, the valve 272 is opened to drain the oil from the compressor 111 that is currently in operation.
It is collected through the connecting pipe 23. Valve 272 is normally closed. According to this, similarly to the above, the compressor 112
The amount of oil within is reliably maintained within the proper range. In addition,
The compressor 111 is the same as the compressor 112, so a description thereof will be omitted.

[0034]

As is clear from the above description, according to the present invention, return pipes are connected to each other by a connecting pipe, a valve is provided in the connecting pipe and/or the return pipe, and a valve is provided for controlling the opening and closing of the valve. Since multiple oil level detectors are installed on the compressor at different heights, the oil level in the compressor can be precisely controlled according to the high and low oil levels during compressor operation. Appropriate balance between multiple compressors can be maintained.

[Brief explanation of drawings]

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 outdoor unit.

FIG. 3 is a flowchart showing control by a controller.

FIG. 4 is a diagram showing zones based on detected values of an oil level detector.

FIG. 5 is a system diagram of an outdoor unit showing another embodiment.

FIG. 6 is a system diagram of an outdoor unit showing still another embodiment.

FIG. 7 is a diagram showing zones based on the detected values of the oil level detector.

FIG. 8 is a system diagram of an outdoor unit showing still 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 Oil level detector a, b, c
level 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 to control the operation of these compressors simultaneously and individually according to the load, the return pipes are connected with a connecting pipe, and a valve is provided in the connecting pipe and/or the return pipe. A refrigeration system characterized in that a plurality of oil level detectors for controlling the opening and closing of the valve are attached to the compressor at different heights.