JPH08200856A - Operation controller for refrigerator - Google Patents

Abstract

PURPOSE: To limit the capacity of a compressing mechanism only as required by detecting the decreasing state of the concentration of the lubricating oil of the mechanism due to liquid refrigerant and limiting the capacity of the mechanism based on the decreased state of the detected oil temperature. CONSTITUTION: A first compressor COMP-1 and a second compressor COMP-2 having larger pressure loss of the suction side than that of the compressor COMP-1 are aligned in parallel. The oil is separated from the mixed fluid discharged by the mechanism 21, returned to the suction side of the compressor COMP-1 by an oil returning mechanism 70, and the oil of the compressor COMP-1 is supplied to the compressor COMP-2 via an oil equalizing tube 75 in response to the operation of the compressor COMP-2. Further, the oil temperature of the compressor COMP-1 is detected by an oil temperature detecting means Th5 of a concentration detecting means 6, and the decrease state of the oil concentration is detected by a concentration deciding means 8 based on the detected oil temperature. The operation of the compressor COMP-2 is stopped based on the decision. Accordingly, the oil concentration can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for a refrigerating device such as an air conditioner, and more particularly to a measure for reducing oil concentration in a compression mechanism of the refrigerating device.

[0002]

2. Description of the Related Art For example, as an air conditioner, there is one described in Japanese Patent Application Laid-Open No. 6-341721. In this system, as a compression mechanism for sucking in and compressing and discharging the refrigerant, the first compressor that is always operated in advance and the first compressor
It is provided with a so-called twin type compression mechanism in which a second compressor that is operated subsequently to the compressor is installed in parallel. Then, in order to operate the compression mechanism without stress, while sucking the mixed gas in which the lubricating oil is mixed with the refrigerant into the compression mechanism, the lubricating oil is separated from the mixed gas discharged by the compression mechanism, It is designed such that it is returned to the suction side of the compression mechanism, and the sliding point in the compression mechanism is lubricated by the lubricating oil.

Specifically, in the air conditioner, an oil separator for separating lubricating oil from the mixed gas discharged by the compression mechanism, and a lubricating oil separated by the oil separator for the first compressor. The oil return pipe returning to the suction side of the first compressor and the first low pressure depending on the low pressure generated in the second compressor by the operation of the second compressor.
An equalizing pipe for supplying the lubricating oil of the compressor to the second compressor is provided, which ensures that a required amount of lubricating oil is secured in each compressor.

By the way, when the liquid refrigerant is accumulated in the accumulator arranged on the suction side of the compression mechanism by a liquid bag or the like and the liquid refrigerant is sucked into the compression mechanism even if little by little. Since the concentration of the lubricating oil is reduced by this liquid refrigerant, resulting in poor lubrication, the stress of the compression mechanism may increase.

In particular, in recent years, for example, in an air conditioner, indoor or outdoor units have been multi-functionalized (multi-pluralization), and the increasing tendency of the amount of refrigerant accompanying such multi-functionalization has led to a decrease in oil concentration. Since they are directly connected, the stress of the compression mechanism due to the decrease of the oil concentration becomes more remarkable.

Therefore, conventionally, in the operating state in which the liquid refrigerant is likely to be sucked into the compression mechanism, the capacity of the compression mechanism is limited periodically and for a predetermined time (for example,
(If the compression mechanism is controlled in two stages of operation and stop, stop it) so that the progress of the decrease of the oil concentration is stopped and the oil concentration is improved with the decrease of the liquid refrigerant. It is designed to wait for you.

[0007]

However, in the above-mentioned conventional operation control, the capacity of the compression mechanism is limited irrespective of the actual oil concentration and with sufficient safety in mind. There is a problem that efficiency must be reduced.

The present invention has been made in view of the above problems, and an object thereof is to limit the capacity of a compression mechanism in a refrigerating apparatus such as an air conditioner only when it is necessary. It is intended to prevent an increase in the stress of the compression mechanism due to a decrease in the oil concentration while suppressing a decrease in the efficiency of the compression mechanism due to.

[0009]

In order to achieve the above object, the invention of claim 1 detects the actual state of decrease of the oil concentration by detecting the state of decrease of the oil concentration. The capacity of the compression mechanism is limited based on the detection result.

Specifically, in the present invention, as shown in FIG. 1, a variable capacity compression mechanism (21) for sucking and compressing and discharging a mixed fluid in which a lubricating oil is mixed with a refrigerant, and this compression mechanism ( Oil return means (7) for separating lubricating oil from the mixed fluid discharged by (21) and returning it to the suction side of the compression mechanism (21)
0) and the operation control device of the refrigeration system provided with.

Then, the concentration detecting means (6) for detecting the state of decrease in the concentration of the lubricating oil of the compression mechanism (21) due to the liquid refrigerant, and the state of decrease in the oil concentration detected by the concentration detecting means (6) are detected. Based on this, the control means (7) for limiting the capacity of the compression mechanism (21) is provided.

According to a second aspect of the invention, in the above-mentioned first aspect of the invention, when the compression mechanism (21) is composed of an inverter compressor whose capacity changes in accordance with an input frequency, a control means ( It is assumed that 7) is configured to limit the capacity of the inverter compressor (21) by setting the upper limit frequency of the inverter compressor (21).

According to a third aspect of the present invention, in the above-mentioned first aspect, the compression mechanism (21) is located on the suction side of the first compressor (COMP-1) and the first compressor (COMP-1). The second compressor (COMP-2) having a large pressure loss is arranged in parallel, and the oil return means (70) transfers the separated lubricating oil to the suction side of the first compressor (COMP-1). Is configured to return,
According to the low pressure generated in the second compressor (COMP-2) due to the operation of the second compressor (COMP-2), the first compressor (CO
When the oil equalizing means (75) for supplying the lubricating oil of MP-1) to the second compressor (COMP-2) is provided, the control means (7) controls the second compressor (COMP-2). It is assumed that the capacity of the compression mechanism (21) is limited by limiting the operation of.

According to the invention of claim 4, in the invention of claim 3, the first compressor (COMP-1) of the compression mechanism (21) is
In the case where the control means (7) is constituted by an inverter compressor that operates according to the input frequency, the control means (7) controls the operation of the second compressor (COMP-2) as well as the first compressor (CO2).
It is assumed that the capacity of the compression mechanism (21) is limited by setting the upper limit frequency of MP-1).

According to a fifth aspect of the present invention, in the above-mentioned first aspect, the concentration detecting means (6) includes an oil temperature detecting means (Th51) for detecting the temperature (To) of the lubricating oil of the compression mechanism (21). ,
Consistency determining means (8) for determining the state of decrease in the concentration of the lubricating oil due to the liquid refrigerant based on the temperature (To) of the lubricating oil detected by the oil temperature detecting means (Th51). Further, the concentration determining means (8) determines that the oil concentration is decreasing when the temperature (To) of the lubricating oil detected by the oil temperature detecting means (Th51) is equal to or lower than a predetermined value. It is assumed that it is configured as follows. Then, the control means (7), when the concentration determination means (8) determines that the decrease of the oil concentration is in progress, the compression mechanism (21).
Be configured to limit the capacity of the.

According to a sixth aspect of the present invention, in the above fifth aspect of the invention, the concentration determining means (8) includes an oil temperature detecting means (8) after the capacity of the compression mechanism (21) is limited by the control means (7). It is assumed that when the temperature (To) of the lubricating oil detected by Th51) rises above a second predetermined value higher than the predetermined value, it is determined that the oil concentration has improved. The control means (7) is configured to release the capacity limitation of the compression mechanism (21) when the oil concentration is determined to be improved by the concentration determination means (8). .

[0017]

With the above construction, in the first aspect of the invention, the concentration detecting means (6) detects the state of decrease in the concentration of the lubricating oil of the compression mechanism (21) due to the liquid refrigerant, and based on the state of decrease in the oil concentration, The capacity of the compression mechanism (21) is limited by the control means (7). As a result, the amount of liquid refrigerant sucked into the compression mechanism (21) is reduced, and the progress of the decrease in oil concentration is suppressed. Therefore, the efficiency of the compression mechanism is significantly reduced by suppressing the decrease in the oil concentration in the compression mechanism (21) until the oil concentration improves as the liquid refrigerant decreases. Without letting
The oil concentration can be improved, and the increase in the stress of the compression mechanism (21) due to the decrease in the oil concentration can be efficiently prevented.

According to the second aspect of the present invention, the upper limit frequency of the inverter compressor (21) is set by the control means (7) based on the lowered state of the oil concentration detected by the concentration detection means (6). Therefore, when the upper limit frequency is set low, the operation of the invention of claim 1 is performed. On the other hand, when it is set high, the overload of the inverter compressor (21) is prevented in advance.

According to the third aspect of the invention, the operation of the second compressor (COMP-2) of the compression mechanism (21) is controlled by the control means (based on the state of decrease in the oil concentration detected by the concentration detection means (6). 7), which limits the overall capacity of the compression mechanism (21). As a result, in addition to the effect of the first aspect of the invention, a sufficient amount of lubricating oil can be secured in the first compressor (COMP-1). That is, since the low pressure state of the second compressor (COMP-2) is alleviated by the above operation restriction, the lubricating oil returned to the first compressor (COMP-1) by the oil returning means (70) is equalized. The means (75) suppresses the supply to the second compressor (COMP-2).

Therefore, the decrease in the oil concentration in the first compressor (COMP-1) can be efficiently suppressed, and the action of the invention according to claim 3 can be efficiently performed.

According to the invention of claim 4, the control means (7) limits the operation of the second compressor (COMP-2) on the basis of the lowered state of the oil concentration detected by the concentration detecting means (6). In addition, the first compressor (CO
The upper limit frequency of MP-1) is set. As a result, in addition to the effect of the invention of claim 3, the effect of claim 2 is performed.

In the fifth aspect of the invention, in the concentration detecting means (6), first, the temperature (To) of the lubricating oil of the compression mechanism (21) is detected by the oil temperature detecting means (Th51), and then,
Based on the oil temperature (To), the concentration determination means (8) determines the state of decrease in the concentration of the lubricating oil due to the liquid refrigerant.
This is based on the knowledge of the present inventors that the oil temperature lowers as the oil concentration decreases, and the concentration determining means (8) uses the oil temperature (To) equal to or lower than a predetermined value. When it is, it is determined that the decrease of the oil concentration is progressing. Then, when the concentration determining means (8) determines that the oil concentration is decreasing, the control means (7) limits the capacity of the compression mechanism (21). Therefore, the capacity of the compression mechanism (21) is limited at an appropriate timing according to the progress of the decrease in the oil concentration.

In the invention of claim 6, the control means (7) is provided.
When the capacity of the compression mechanism (21) is restricted by
When the temperature (To) of the lubricating oil detected by the oil temperature detecting means (Th51) rises above a second predetermined value higher than the predetermined value, the concentration determining means (8) improves the oil concentration. It is determined that Based on this determination, the control means (7)
Remove the capacity limitation of the compression mechanism (21). Therefore, the capacity limitation of the compression mechanism (21) is released at an appropriate timing according to the improved state of the oil concentration.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

-Overall Structure-As shown in FIG. 2, in the air conditioner (10) as the refrigerating apparatus according to this embodiment, the first to third outdoor units (2A, 2B, 2C) are provided. 3 indoor units (3A, 3B,
3C) are connected in parallel to the main liquid line (4L) and the main gas line (4G), respectively.

Each of the outdoor units (2A, 2B, 2C) has a compression mechanism (21), a four-way switching valve (22), and an outdoor fan (23).
-F) is an outdoor heat exchanger (23) which is a heat source side heat exchanger and an outdoor electric expansion valve (2) which is a heat source side expansion mechanism.
4) and are included in the heat source unit. The outdoor heat exchanger (23) functions as a condenser during cooling operation and as an evaporator during heating operation, and has a refrigerant pipe (25) at one end (right end in FIG. 2) on the gas side thereof. ), And branch liquid lines (5L-A, 5L-B, 5L-C) are connected to the other end (left end in the figure) on the liquid side, respectively. The outdoor electric expansion valve (24) is provided in each of the branch liquid lines (5L-A, 5L-B, 5L-C). A receiver (11) is arranged at the connection between the branch liquid line (5L-A, 5L-B, 5L-C) and the main liquid line (4L), and each receiver is branched by this receiver (11). The liquid lines (5L-A, 5L-B, 5L-C) and the main liquid line (4L) are connected.

Refrigerant piping (2) on the side of the outdoor heat exchanger (23)
5) is switchably connected to the discharge side and suction side refrigerant pipes (25, 25) of the compression mechanism (21) by a four-way switching valve (22). An accumulator (26) is provided in the suction side refrigerant pipe (25). On the other hand, the refrigerant pipes (25, 2) on the discharge side and the suction side of the compression mechanism (21).
5) is a branch gas line (5G-
A, 5G-B, 5G-C) are switchably connected. The branch gas lines (5G-A, 5G-B, 5G-C) are connected to the main gas line (4G).

The first to third outdoor units (2A, 2B,
2C), the first outdoor unit (2A) shown in FIG. 3 is the second outdoor unit (2B) and the third outdoor unit (2B) as slave units shown in FIG.
It is a master unit that operates prior to the outdoor unit (2C), and the first outdoor unit (2A) and the second and third outdoor units (2B, 2C) differ mainly in the configuration of the compression mechanism (21). ing.

That is, the compression mechanism (21) of the first outdoor unit (2A) is an inverter-controlled upstream compressor (COMP-1) as a variable displacement first compressor whose capacity is controlled in multiple stages. And a downstream-side compressor (COMP-2) as a constant-capacity second compressor controlled to two types of operation and stop, are connected in parallel to form a so-called twin type. On the other hand, each of the compression mechanisms (21, 21) of the second and third outdoor units (2B, 2C) is a constant capacity upstream compressor (COMP-1) that is controlled to two types of operation and stop. And a downstream compressor (COMP-2), both of these compressors (COMP-1,
COMP-2) is connected in parallel to form a twin type. And in any of the outdoor units (2A, 2B, 2C), the upstream compressor (COMP-1) is the downstream compressor (COMP-2).
It is designed to operate prior to.

On the other hand, the above indoor units (3A, 3B, 3C)
Includes an indoor heat exchanger (31), which is a usage-side heat exchanger in which an indoor fan (31-F) is arranged in close proximity, and an indoor electric expansion valve (32), which is a usage-side expansion mechanism. I am configuring. The indoor heat exchanger (31) functions as an evaporator during a cooling operation and as a condenser during a heating operation, and is connected to the main liquid line (4L) through an indoor liquid pipe (3L). The main gas line (4G) is connected to the main gas line (4G) through an indoor gas pipe (3G). An indoor electric expansion valve (32) is provided in the indoor liquid pipe (3L).

-Structure of Piping Unit- In the air conditioner (10), the outdoor units (2A, 2B,
2C) and the indoor units (3A, 3B, 3C) are provided with a piping unit (12) which is a connection circuit part. In this piping unit (12), the outdoor units (2A, 2B,
2C) branch liquid line (5L-A, 5L-B, 5L-C) and branch gas line (5G-A, 5G-B, 5G-C), and main liquid line (4L)
And the main gas line (4G) is connected.

Specifically, the branch liquid line (5L-A, 5L
-B, 5L-C) each branch liquid pipe (5LAa, 5LBa, 5LCa) extending from each outdoor unit (2A, 2B, 2C) to the outside, and each branch liquid pipe (5LAa, 5LBa, 5LCa) It is equipped with each branch liquid passage (5LAb, 5LBb, 5LCb) continuous to the outer end.

The branch gas line (5G-A, 5G-B, 5G-C)
Is each branch gas pipe (5GAa, 5GBa, 5GCa) extending from each outdoor unit (2A, 2B, 2C) to the outside, and each of the branch gas pipes (5GAa, 5GBa, 5GCa) continuous to each outer end. It has a branch gas passage (5GAb, 5GBb, 5GCb).

The main liquid line (4L) is connected to the indoor liquid pipes (3L) of the indoor units (3A, 3B, 3C) and the main liquid pipe (4L-a) and the main liquid pipe (4L). -a) is connected to the main liquid passage (4L-b) that is continuous with one end and has the branch liquid passages (5LAb, 5LBb, 5LCb) of the outdoor unit (2A, 2B, 2C) communicating with each other via the receiver (11). It is composed by.

The main gas line (4G) is connected to the indoor gas pipes (3G) of the indoor units (3A, 3B, 3C) and the main gas pipe (4G-a) and the main gas pipe (4G).
-a) is composed of a main gas passage (4G-b) that is continuous with one end and each branch gas passage (5GAb, 5GBb, 5GCb) of the outdoor unit (2A, 2B, 2C) is continuous.

In the piping unit (12), the branch liquid lines (5L-A, 5L) on the outdoor unit (2A, 2B, 2C) side are provided.
-B, 5L-C) branch liquid passages (5LAb, 5LBb, 5LCb) and branch gas lines (5G-A, 5G-B, 5G-C) branch gas passages (5GAb, 5GBb, 5GCb) The main liquid passage (4L-b) of the main liquid line (4L), the main gas passage (4G-b) of the main gas line (4G), and the receiver (11) are integrally formed into a unit. There is.

Further, the pipe unit (12) is integrally formed with a first gas on-off valve (VR-1) and a second gas on-off valve (VR-2). 1st gas on-off valve (VR-1)
Is the branch gas passage (5GBb) on the second outdoor unit (2B) side
It is provided in the, and constitutes an opening and closing mechanism that opens and closes this branch gas passage (5 GBb). On the other hand, the second gas on-off valve (VR
-2) is the branch gas passage (5G) on the side of the third outdoor unit (2C)
It is provided in Cb) and constitutes an opening / closing mechanism for opening / closing this branch gas passage (5GCb).

The first gas on-off valve (VR-1) and the second gas on-off valve (VR-2) are external pressure equalizing type reversible valves,
Pilot circuit (50) for these on-off valves (VR-1, VR-2)
Is connected. Each of the pilot circuits (50) has two check valves (CV, CV), a branch gas passage (5GAb) on the side of the first outdoor unit (2A), and a first after-mentioned first
A high pressure circuit (51) connected to the first oil leveling auxiliary passage (77-A) on the outdoor unit (2A) side for guiding high pressure refrigerant and a low pressure circuit (52) for maintaining a low pressure state are provided. .

The pilot circuit (50) includes a high pressure circuit (51) and a low pressure circuit (52) by means of a switching valve (50-S).
And the first gas on-off valve (VR-1) and the second gas on-off valve (VR-
2) is switched and connected, and when the second outdoor unit (2B) is stopped during heating operation, the first gas on-off valve (VR-1) is controlled to be fully closed, while at the time of heating operation. When the third outdoor unit (2C) in the
Control the gas on-off valve (VR-2) so that it is fully closed.

The second outdoor unit (2B) and the third outdoor unit (2B)
The outdoor electric expansion valves (24, 24) of the outdoor unit (2C) are not arranged in the piping unit (12), but the first gas on-off valve (VR-1) and the second on-off valve (VR) are used. -2) corresponding to the branch liquid line (5L-A, 5L-B, 5L-C) is also used as an opening and closing mechanism, the second outdoor unit (2B) during cooling operation and heating operation Also, it is designed to be fully closed when the third outdoor unit (2C) is stopped.

-Structure of Pressure Equalizing Line- A pressure equalizing line (60) is arranged between the outdoor units (2A, 2B, 2C). This pressure equalization line (60)
It is connected to the gas side refrigerant piping (25, 25, 25) of the outdoor heat exchanger (23) in each outdoor unit (2A, 2B, 2C), and both are connected between each outdoor unit (2A, 2B, 2C). It is designed to allow the refrigerant to flow in the right direction.

The pressure equalizing line (60) is a pressure equalizing pipe (61-A, 61-B,) extending outward from each outdoor unit (2A, 2B, 2C).
61-C) and respective pressure equalizing passages (62) continuous to the outer ends of these pressure equalizing tubes (61-A, 61-B, 61-C). The pressure equalizing passage (62) is connected to the piping unit (12).
Is formed on the first outdoor unit (2A) side to the second
The branch pipe branching to the outdoor unit (2B) side is provided with a first pressure equalizing valve (SVB1), and the branch pipe branching to the third outdoor unit (2C) side is provided with a second pressure equalizing valve (SVB2). Has been.

The first pressure equalizing valve (SVB1) is fully closed when the cooling operation of the second outdoor unit (2B) is stopped to prevent the refrigerant from flowing to the outdoor unit (2B). . On the other hand, the second pressure equalizing valve (SVB2) is fully closed when the cooling operation of the third outdoor unit (2C) is stopped to prevent the refrigerant from flowing to the outdoor unit (2C).

-Configuration of Auxiliary Refrigerant Circuit- Each of the outdoor units (2A, 2B, 2C) has a compression mechanism (2
Oil return mechanism (7) for returning the lubricating oil to 1)
0) is provided. The oil return mechanism (70) includes an oil separator (71), a first oil return pipe (72), a second oil return pipe (73), and an oil leveling bypass pipe (74). .

On the other hand, the suction pipe (25-S) of the downstream compressor (COMP-2) which is a part of the refrigerant pipe (25) is the suction pipe (25-S of the upstream compressor (COMP-1). The pressure loss is set to be larger than that of S), and an oil equalizing pipe (75) as an oil equalizing means is connected between both compressors (COMP-1, COMP-2). As a result, when both compressors (COMP-1, COMP-2) are operating, the downstream compressor (COMP-2), which is at a relatively lower pressure side than the upstream compressor (COMP-1). ) Will be supplied with lubricating oil for the upstream compressor (COMP-1).

The oil separator (71) is provided with both discharge pipes (25-D, 25-D) of the upstream compressor (COMP-1) and the downstream compressor (COMP-2) which are part of the refrigerant pipe (25). 25-D) is installed at the confluence of the discharge pipe (25-D) of each compressor (COMP-1, COMP-2).
D, 25-D) are equipped with check valves (CV-1, CV-2). Furthermore, between the upper part of the upstream compressor (COMP-1) and the downstream side of the check valve (CV-1) of the discharge pipe (25-D), and the upper part of the downstream compressor (COMP-2). Between the discharge pipe (25-D) and the upstream side of the check valve (CV-2).
6, 76) are connected. And these oil drain pipes (7
6, 76) is configured to discharge the lubricating oil accumulated in the upper portion of the scroll compressor to the discharge pipes (25-D, 25-D). Further, the check valve (CV-1) of the upstream compressor (COMP-1) is provided with a conduit resistance so as to discharge the lubricating oil when the refrigerant circulation amount is small.

The first oil return pipe (72) is equipped with a capillary tube (CP) and has an oil separator (71) and a first compressor (CO).
It is connected to the suction pipe (25-S) of the MP-1) and the lubricating oil accumulated in the oil separator (71) is always fed to the suction pipe (25-S) of the first compressor (COMP-1). It is designed to be returned. The second oil return pipe (73) is provided with an oil return valve (SVP2) and is connected to the oil separator (71) and the suction pipe (25-S) of the second compressor (COMP-2). By opening the oil return valve (SVP2) every predetermined time, the lubricating oil accumulated in the oil separator (71) is returned to the suction pipe (25-S) of the second compressor (COMP-2). It is done like this.

The oil equalizing bypass pipe (74) is connected to the oil equalizing valve (SVO
1), one end is upstream of the oil return valve (SVP2) of the second oil return pipe (73), and the other end is the pressure equalizing line (6
0) equalizing pipes (61-A, 61-B, 61-C), respectively. Then, in order to execute the oil equalizing operation together with the oil equalizing bypass pipe (74), the pressure equalizing passage (62) of the pressure equalizing line (60) is provided with a first pressure equalizing auxiliary passage (77-A) and a first pressure equalizing auxiliary passage (77-A). The second oil equalization auxiliary passage (77-B) and the third pressure equalization auxiliary passage (77-C) are connected. Each of these pressure equalization auxiliary passages (77-A, 77-B, 77
-C) is integrated into the piping unit (12).

The first pressure equalizing auxiliary passage (77-A) has one end on the first outdoor unit (2A) side of the pressure equalizing passage (62) and the other end on the second outdoor unit (2B) and the third outdoor unit (2B). Outdoor unit (2
C) is connected to the confluence of the branch gas passages (5GBb, 5GCb), respectively, and the first oil level auxiliary valve (SVY1) and the check valve (C
V) and.

The second pressure equalizing auxiliary passage (77-B) has one end on the side of the second outdoor unit (2B) of the pressure equalizing passage (62) and the other end of the branch gas of the first outdoor unit (2A). Connected to the passage (5GAb), the second oil leveling auxiliary valve (SVY2) and the check valve (C
V) and.

The third pressure equalizing auxiliary passage (77-C) has one end on the third outdoor unit (2C) side of the pressure equalizing passage (62) and the other end on the branch gas of the first outdoor unit (2A). Connected to the passage (5GAb), the third oil leveling auxiliary valve (SVY3) and the check valve (C
V) and.

The oil equalizing valve (SVO1, SVO1, SVO1)
And the first to third oil leveling auxiliary valves (SVY1, SVY2, SVY3) are 2
Opening and closing when performing oil equalization operation once every 3 hours (for example, 2 to 3 minutes), or when performing the oil equalization operation such as after completion of oil return operation or after defrost operation during heating operation It is designed to do.

Incidentally, between the branch gas passage (5GBb) of the second outdoor unit (2B) and the second pressure equalizing auxiliary passage (77-B), and the branch gas passage (5GCb) of the third outdoor unit (2C). ) And the third pressure equalizing auxiliary passage (77-C), a capillary tube (CP) is provided, and the first gas on-off valve (VR) is provided during heating operation.
-1) and the auxiliary refrigerant passages (12-s, 12-s) for releasing the refrigerant leaking from the second gas on-off valve (VR-2) are connected.

In addition, the above outdoor units (2A, 2B, 2C)
The liquid injection pipe (2j) is connected to the branch liquid pipes (5LAa, 5LBa, 5LCa) of the liquid injection pipe (2j), and the liquid injection pipe (2j) is branched into two, and the injection valves (SVT1, SVT2) And a capillary tube (CP, CP) through which the upstream side compressor (COMP-1) and the downstream side compressor (COMP-2) are respectively connected. The liquid injection valves (SVT1, SVT2) are designed to open when the temperature of the discharge gas refrigerant of each compressor (COMP-1, COMP-2) rises excessively to reduce the temperature of the discharge gas refrigerant.

A hot gas bypass pipe (2h) is connected between the discharge side and the suction side of the compression mechanism (21) in each of the outdoor units (2A, 2B, 2C). This hot gas bypass pipe (2h) is equipped with a hot gas valve (SVP1), and upstream of the four-way switching valve (22) and the accumulator (26).
Connected to the upstream side of. Above hot gas valve (SVP
1) is designed to equalize the discharge side and the suction side of the compression mechanism (21) mainly at the time of starting.

In the second outdoor unit (2B) and the third outdoor unit (2C), an auxiliary bypass pipe (2b) is connected between the suction side and the discharge side of the compression mechanism (21).
This auxiliary bypass pipe (2b) is provided with a check valve (CV) that allows the refrigerant to flow only from the suction side to the discharge side of the compression mechanism (21), and the upstream side of the four-way switching valve (22) and the accumulator. It is connected to the upstream side of (26). Further, the auxiliary bypass pipe (2b) allows the refrigerant in the branch gas lines (5G-B, 5G-C) to operate the compression mechanism (21) when the outdoor units (2B, 2C) are stopped during the heating operation. It bypasses and is sucked by the first outdoor unit (2A).

The receiver (11) and pilot circuit (50) low-voltage circuit (52) in the piping unit (12).
A gas vent passage (12-g) is connected between and.
The gas vent passage (12-g) is equipped with a gas vent valve (SVTG) and is incorporated in the piping unit (12). The gas vent valve (SVTG) is designed to open mainly for high pressure protection during cooling operation and low pressure protection during heating operation.

-Structure of Sensors- Various sensors are provided in the outdoor units (2A, 2B, 2C) and the indoor units (3A, 3B, 3C).
First, in each outdoor unit (2A, 2B, 2C), the outdoor air temperature sensor (Th-1) that detects the outdoor air temperature is connected to the outdoor heat exchanger (2
An outdoor liquid temperature sensor (Th-2) that detects the liquid refrigerant temperature of the outdoor heat exchanger (23) is provided near the branch liquid line (5L-
Discharge gas temperature sensor (Th31, Th) that detects the discharge gas refrigerant temperature of the compression mechanism (21) in the distribution pipe of A, 5L-B, 5L-C)
32) is the discharge pipe (25-D, 25 of each compressor (COMP-1, COMP-2)
-D), an intake gas temperature sensor (Th-4) for detecting the intake gas refrigerant temperature of the compression mechanism (21) is installed in the intake side refrigerant pipe (25) of the compression mechanism (21), and each compressor (COMP -1, COMP-2)
Oil temperature sensor (Th51, Th
52) is the lower part of each compressor (COMP-1, COMP-2), and the outdoor gas temperature sensor (Th-6) for detecting the temperature of the gas refrigerant in the outdoor heat exchanger (23) is the refrigerant pipe on the gas side ( 25). Of the above oil temperature sensors (Th51, Th52),
The oil temperature sensor (Th51) that detects the temperature of the lubricating oil of the upstream compressor (COMP-1) constitutes the oil temperature detecting means in this invention.

Further, in the first outdoor unit (2A), the high pressure sensor (SP-H) for detecting the discharge refrigerant pressure of the compression mechanism (21) is connected to the discharge side refrigerant pipe (25) of the compression mechanism (21).
Further, the low-pressure pressure sensor (SP-L) for detecting the suction refrigerant pressure of the compression mechanism (21) is connected to the suction side refrigerant pipe (2) of the compression mechanism (21).
5) and each compressor (COM
High pressure protection switch (H-PS, H-PS) that operates when the discharge refrigerant pressure of P-1 and COMP-2) reaches a specified high pressure is used for each compressor (COMP-
1, COMP-2) is provided on the discharge pipe (25-D, 25-D).

Further, since the second outdoor unit (2B) and the third outdoor unit (2C) have the pressure equalizing line (60), the high pressure sensor (SP-H) like the first outdoor unit (2A) is used. ) And low pressure sensor (SP-L) are not provided, and high pressure protection switch (H-PS, H that operates when the discharge refrigerant pressure of each compressor (COMP-1, COMP-2) reaches a specified high pressure. -PS) is the discharge pipe (25-D, 25-D) of each compressor (COMP-1, COMP-2)
In addition, the high pressure control switch (HPSC) that operates when the discharge refrigerant pressure of the compression mechanism (21) reaches a predetermined high pressure that is lower than that of the high pressure protection switch (H-PS, H-PS) In the discharge side refrigerant pipe (25) of the compression mechanism (21), a low pressure protection switch (L-PS) which operates when the suction refrigerant pressure of the compression mechanism (21) becomes a predetermined low pressure is provided. 25).

On the other hand, in each indoor unit (3A, 3B, 3C), the room temperature sensor (Th-7) for detecting the indoor air temperature is located near the indoor fan (31-F), and the indoor heat exchanger (31). The indoor liquid temperature sensor (Th-8) that detects the temperature of the liquid refrigerant in the indoor liquid pipe (3L), and the indoor gas temperature sensor (Th-9) that detects the temperature of the gas refrigerant in the indoor heat exchanger (31) It is installed in each indoor gas pipe (3G).

-Basic Control Configuration- The air conditioner (10) includes a controller (80). The detection signals of the sensors (Th-1 to SP-L) and switches (H-PS to L-PS) are input to the controller (80). 1 ~ SP-L)
The opening degree of each electric expansion valve (24 to 32) and the capacity of each compression mechanism (21) are controlled on the basis of the detection signals of the above.

-Operation of Air Conditioning Operation- Next, the basic control operation of the air conditioning operation in the air conditioner (10) will be described.

First, during the cooling operation, the four-way switching valve (22) is switched to the position shown by the solid line in FIGS. 3 and 4.
Then, the high-pressure gas refrigerant discharged from the compression mechanism (21) of each outdoor unit (2A to 2C) is condensed in the outdoor heat exchanger (23) to become a liquid refrigerant, and this liquid refrigerant is supplied to each branch liquid line ( Join the main liquid line (4L) via 5L-A to 5L-C). After that, the liquid refrigerant is decompressed by the indoor electric expansion valve (32) and then evaporated in the indoor heat exchanger (31) to become a low pressure gas refrigerant, which is the main gas line (4G).
And split into each branch gas line (5G-A to 5G-C) via
Returning to the compression mechanism (21) of each outdoor unit (2A to 2C), this circulation operation is repeated.

On the other hand, during the heating operation, the four-way switching valve (22) is switched to the position shown by the broken lines in FIGS. 3 and 4. Then, the compression mechanism (2A to 2C) of each outdoor unit (2A to 2C)
The high-pressure gas refrigerant discharged from 1) joins the main gas line (4G) via each branch gas line (5G-A to 5G-C) and then flows to the indoor unit (3A to 3C). And
This gas refrigerant is condensed in the indoor heat exchanger (31) to become a liquid refrigerant, and this liquid refrigerant is split into each branch liquid line (5L-A to 5L-C) via the main liquid line (4L). To be done. Then, in each outdoor unit (2A to 2C), this liquid refrigerant is decompressed by the outdoor electric expansion valve (24) and evaporated in the outdoor heat exchanger (23) to become a low-pressure gas refrigerant, and the compression mechanism (21).
Then, the circulation operation is repeated.

In the above cooling operation and heating operation,
The controller (80) controls the opening degree of each indoor electric expansion valve (32) and each outdoor electric expansion valve (24), and the compression mechanism (21) in each outdoor unit (2A to 2C) corresponding to the indoor load. Control the capacity of. Specifically, the controller (80) controls the capacity of the upstream compressor (COMP-1) of the first outdoor unit (2A) in a substantially linear manner in accordance with the load by inverter control, and at the same time, the first outdoor unit (2A)
Operation of the downstream side compressor (COMP-2) and each compressor (COMP-1, COMP-2) of the second and third outdoor units (2B, 2C)
Control each stop. For example, when the load on the indoor units (3A to 3C) decreases, the third outdoor unit (2
C) and the second outdoor unit (2B) are stopped in this order,
Conversely, when the load on the indoor units (3A to 3C) increases, the second outdoor unit (2B) and the third outdoor unit (2C) start operating in that order.

Further, in both the cooling operation and the heating operation, the first pressure equalizing valve (SVB1) and the second pressure equalizing valve (SVB2) are opened while the outdoor units (2A to 2C) are operating. Keep it. As a result, during cooling operation, the high-pressure gas refrigerant flows through the outdoor heat exchangers (23) substantially evenly, while during heating operation, the low-pressure gas refrigerant flows through the outdoor heat exchangers (23) substantially uniformly. become.

That is, during the cooling operation, for example, when the operating capacity of the third outdoor unit (2C) becomes large with respect to the cooling load, a part of the refrigerant discharged from the compression mechanism (21) is partially equalized by the pressure equalizing line (60). ) To the outdoor heat exchangers (23) of the first outdoor unit (2A) and the second outdoor unit (2B). On the contrary, during the heating operation, for example, when the operating capacity of the third outdoor unit (2C) becomes large with respect to the heating load, each compression mechanism (21) of the first outdoor unit (2A) and the second outdoor unit (2B). ) Part of the refrigerant is passed through the pressure equalizing line (60) to the compression mechanism (2C) of the third outdoor unit (2C).
It will be sucked into 1).

-Opening and closing operations of various valves-When the cooling operation of the third outdoor unit (2C) is stopped,
The outdoor electric expansion valve (24) and the second of the outdoor unit (2C)
The pressure equalizing valves (SVB2) are closed to prevent liquid refrigerant from accumulating in the stopped third outdoor unit (2C). Furthermore, if the cooling operation of the second outdoor unit (2B) is also stopped,
Similarly, the outdoor electric expansion valve (24) and the first pressure equalizing valve (SVB1) are each closed to prevent the liquid refrigerant from accumulating in the stopped second outdoor unit (2B), and also to the first outdoor unit (2A ) Etc. and each indoor unit (3A to 3C) are prevented from becoming insufficient in the amount of refrigerant. When the cooling operation of the third outdoor unit (2C) and the second outdoor unit (2B) is stopped, the branch gas lines (5G-A to 5G-C) are in a low pressure state, so the first gas on-off valve (VR -1) and the second gas on-off valve (VR-2) are open.

On the other hand, when the heating operation of the third outdoor unit (2C) is stopped, the outdoor electric expansion valve (24) and the second gas on-off valve (VR-2) are closed to stop the third outdoor unit (2C). )
Prevent liquid refrigerant from accumulating in the. Further, when the heating operation of the second outdoor unit (2B) is also stopped, the outdoor electric expansion valve (24) and the first gas on-off valve (VR-1) are closed in the same manner,
Prevent the liquid refrigerant from accumulating in the stopped second outdoor unit (2B), and make sure that the amount of refrigerant between the first outdoor unit (2A) etc. and each indoor unit (3A-3C) becomes insufficient. Prevent from becoming. When the heating operation of the third outdoor unit (2C) and the second outdoor unit (2B) is stopped, the pressure equalizing line (60) communicates with the low pressure side of the first outdoor unit (2A), etc. (SVB2) and first pressure equalizing valve (SVB1)
Leave it open.

Further, the third outdoor unit (2C) and the second
Immediately after the heating operation of the outdoor unit (2B) is stopped, for example, when the third outdoor unit (2C) is stopped,
The outdoor electric expansion valve (24) and the second gas on-off valve (VR-2) of the outdoor unit (2C) are opened for a predetermined time (for example, 1 to 2 minutes). As a result, the high-pressure gas refrigerant from the first outdoor unit (2A), etc. passes through the branch gas line (5G-C) and the auxiliary bypass pipe (2b) of the third outdoor unit (2C) to the branch liquid line (5L-C). ), The liquid refrigerant in the stopped third outdoor unit (2C) can be discharged to the main liquid line (4L) to prevent a shortage of the refrigerant amount.

Further, during the cooling operation and the heating operation, each oil equalizing valve (SVO1) and each oil equalizing auxiliary valve (SVY1 to SVY3) are closed, while lubrication accumulated in the oil separator (71). Oil is always fed from the first oil return pipe (72) to the upstream compressor (COMP-1)
Return to the suction pipe (25-S). Then, the oil return valve (SVP2) is opened every predetermined time, and the lubricating oil accumulated in the oil separator (71) is supplied from the second oil return pipe (73) to the suction pipe (COMP-2) of the downstream side compressor (COMP-2). 25-S).

Further, in each of the cooling operation and the heating operation, each oil equalizing valve (SVO1) and each oil equalizing auxiliary valve (SV)
Y1 to SVY3) are controlled to be opened and closed appropriately to perform an oil equalizing operation so that the amount of lubricating oil in the compression mechanism (21) of each outdoor unit (2A to 2C) becomes equal.

-Characteristics of the Invention- As a characteristic of the invention, as shown in FIG. 5, the lubrication is performed based on the temperature (To) of the lubricating oil of the compression mechanism (21) detected by the oil temperature sensor (Th51). Concentration determination means (8) for determining the concentration reduction state of the oil due to the liquid refrigerant, and control for limiting the capacity of the compression mechanism (21) based on the reduction state of the lubricating oil concentration determined by the concentration determination means (8) Means (7)
And are provided. Here, the oil temperature sensor (Th51)
The density determining means (8) constitutes the density detecting means in the present invention.

Specifically, the density determining means (8) is
The oil temperature (To) detected by the oil temperature sensor (Th51) of the upstream compressor (COMP-1) is the first predetermined value (for example, -15 ° C).
When it is below, it is determined that the decrease of the oil concentration is progressing. And the control means (7)
Stops the operation of the downstream side compressor (COMP-2) of each outdoor unit (2A to 2C) when it is determined by the concentration determination means (8) that the oil concentration is decreasing. , This limits the capacity of each compression mechanism (21). further,
For the first outdoor unit (2A), set the upper limit frequency of the upstream compressor (COMP-1) as an inverter compressor (for example, when max is 116 Hz, the upper limit frequency is 96 Hz, which is approximately 90%). Is set).

On the other hand, after the capacity of the compression mechanism (21) is limited by the control means (7), the concentration determination means (8) outputs the oil temperature (To) detected by the oil temperature sensor (Th51). When the temperature is raised to a second predetermined value (for example, −10 ° C.) higher than the first predetermined value, it is determined that the oil concentration has been improved. Then, the control means (7) is configured to release the capacity limitation for the compression mechanism (21) when the concentration determination means (8) determines that the oil concentration has improved.

Specifically, the controller (8
The operation control process relating to the oil concentration in 0) will be described based on the flowchart of FIG.

First, in step S1, after the detection signal of the oil temperature sensor (Th51) is input, the process proceeds to step S2. In this step S2, it is determined whether the oil temperature (To) of the upstream compressor (COMP-1) is lower than -15 ° C (To <-15 ° C). When the determination is NO, the above step S
Return to 1. On the other hand, when the determination is YES, it is considered that the concentration decrease of the lubricating oil due to the liquid refrigerant is progressing, and the process proceeds to step S3.

In step S3, the downstream compressor (CO
Stop the operation of MP-2). In addition, the first outdoor unit (2
For A), further, inverter compressor (COMP-1)
The upper limit frequency of is set to 96 Hz. Then, it moves to step S4.

In step S4, the detection signal of the oil temperature sensor (Th51) is input again, and in step S5, the oil temperature (To) of the upstream compressor (COMP-1) is higher than -10 ° C (To> -10 ° C) is determined. When the determination is NO, the process returns to step S4. On the other hand, when the determination is YES, it is considered that the oil concentration has been improved, and the process proceeds to step S6.

In step S6, the operation stop of the downstream side compressor (COMP-2) is released. Further, for the first outdoor unit (2A), the upper limit frequency of the inverter compressor (COMP-1) is relaxed to the maximum frequency of 106 Hz, and the process is terminated.

In the above processing, the steps S2 and S5 constitute the density determining means (8) in the present invention. The steps S3 and S6 constitute the control means (7) in the present invention.

Therefore, according to this embodiment, for example, the liquid refrigerant is accumulated in the accumulator (26) arranged on the suction side of the compression mechanism (21) by the liquid bag or the like, and the liquid refrigerant is not gradually added. Even if it is sucked into the compression mechanism (21), the operation of the downstream side compressor (COMP-2) is stopped to limit the entire capacity of the compression mechanism (21). The amount of liquid refrigerant sucked into 21) can be reduced, and the progress of the decrease in oil concentration can be suppressed. Therefore, it is possible to improve the oil concentration by suppressing the decrease in the oil concentration in the compression mechanism (21) until the oil concentration is improved as the liquid refrigerant decreases. it can.

Moreover, by stopping the operation of the downstream side compressor (COMP-2), the upstream side compressor (COMP
Since the supply of lubricating oil from -1) to the downstream compressor (COMP-2) is suppressed, it is possible to secure a sufficient amount of lubricating oil for the upstream compressor (COMP-1). 1 compressor (CO
It becomes possible to efficiently suppress the decrease in oil concentration in MP-1), and the compression mechanism (2
It is possible to avoid the large decrease in efficiency of 1).

Moreover, in the first outdoor unit (2A), while the oil concentration is decreasing, the upper limit frequency of the upstream compressor (COMP-1), which is an inverter compressor, is set to about 90% of the maximum frequency. By setting it to a relatively high value, it is possible to prevent the upstream compressor (COMP-1) from overloading and avoid increasing the stress of the compressor (COMP-1) itself.

Then, when the temperature of the lubricating oil is equal to or lower than the first predetermined value, it is considered that the decrease of the lubricating oil concentration is progressing. The capacity of the compression mechanism (21) can be limited at various timings. On the other hand, when the temperature of the lubricating oil rises above the second predetermined value which is higher than the first predetermined value, it is considered that the oil concentration has improved, so it is appropriate according to the improvement state of the oil concentration. The above capacity limitation can be released at a timing.

As a result, it is possible to efficiently prevent the increase of the stress of the compression mechanism (21) due to the decrease of the oil concentration without significantly lowering the efficiency of the compression mechanism (21). Become.

In the above embodiment, the upper limit frequency of the inverter compressor (COMP-1) is set as high as about 90% of the max frequency, but it may be set lower.

In the above embodiment, the operation of the compression mechanism (21) in the first outdoor unit (2A) is restricted by the operation of the downstream compressor (COMP-2) being stopped and the operation of the inverter compressor as the upstream compressor. The upper limit frequency of the compressor (COMP-1) is set together, but only the operation of the downstream compressor (COMP-2) may be stopped.

Further, in the above embodiment, the downstream compressor (CO
Since the MP-2) is controlled by two types of operation and stop, the total capacity of the compression mechanism (21) is limited by stopping it, but it is controlled in multiple stages. If so, it is not always necessary to stop.

In the above embodiment, the compression mechanism (21) is composed of two compressors (COMP-1, COMP-2) on the upstream side and the downstream side. If it is variable, one compressor may constitute the compression mechanism.

In the above embodiment, the first predetermined value is set to − when determining whether the oil concentration is lowered or improved.
Although 15 [deg.] C. and -10 [deg.] C. as the second predetermined value are respectively used as a reference, these values can be set as appropriate according to the type of the air conditioner, its operating conditions, and the like.

In the above embodiment, the outdoor unit (2A to 2C) and the indoor unit (3A to
3C) has been described.
As the air conditioner, one in which only one of the indoor and outdoor units is made multi, or one in which one indoor and outdoor unit is provided may be used.

Further, in the above-mentioned embodiments, the case where the present invention is applied to the air conditioner has been described, but it goes without saying that it can be applied to refrigeration equipment in general.

[0095]

As described above, according to the first aspect of the invention, the operation of the refrigerating apparatus is designed so that the lubricating oil is separated from the mixed fluid discharged by the compression mechanism and returned to the suction side of the compression mechanism. As the control device, the concentration detecting means detects the state of decrease of the lubricating oil concentration due to the liquid refrigerant, and based on the detection result, the control means limits the capacity of the compression mechanism so that the oil concentration can be improved. Because I did
It is possible to prevent the stress of the compression mechanism from increasing due to the decrease in the oil concentration, without significantly reducing the efficiency of the compression mechanism.

According to the second aspect of the present invention, the capacity of the inverter compressor as the compression mechanism is limited by setting the upper limit frequency on the basis of the lowered state of the oil concentration detected by the concentration detecting means. Therefore, according to the level of the upper limit frequency, the effect of the invention of claim 1,
The effect that the overload of the inverter compressor (21) can be avoided can be achieved.

According to the third aspect of the invention, the operation of the second compressor of the first and second compressors constituting the compression mechanism is operated based on the state of decrease in the oil concentration detected by the concentration detecting means. Since the capacity of the compression mechanism as a whole is limited by the limitation, in addition to the effect of the invention of claim 1,
It is possible to suppress the supply of the lubricating oil from the first compressor to the second compressor by the oil leveling means and increase the amount of the lubricating oil of the first compressor by that amount, and the oil concentration decreases as the liquid refrigerant decreases. It is possible to more efficiently suppress the progress of the decrease in the oil concentration in the first compressor until the oil pressure is improved. Therefore, the effect of the invention of claim 1 can be obtained more efficiently.

According to the fourth aspect of the present invention, when the first compressor is an inverter compressor, the operation of the second compressor is restricted in addition to the operation restriction of the second compressor based on the state of decrease in oil concentration. Since the upper limit frequency is set in the machine, the effect of the invention of claim 2 can be obtained in the invention of claim 3.

According to the fifth aspect of the present invention, the concentration determining means is configured to determine that the concentration of the lubricating oil is decreasing when the temperature of the lubricating oil is equal to or lower than the predetermined value. The capacity of the compression mechanism can be limited at an appropriate timing according to the progress of the decrease in the oil concentration.

According to the sixth aspect of the present invention, the concentration determining means determines that the oil concentration has improved when the temperature of the lubricating oil rises above a second predetermined value which is higher than the predetermined value. On the other hand, since the control means is configured to release the capacity limitation of the compression mechanism when it is determined that the oil concentration is improved, the capacity of the compression mechanism is adjusted at an appropriate timing according to the improved state of the oil concentration. The restrictions can be lifted.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a refrigerant circuit diagram showing an overall configuration of an air conditioner according to an embodiment of the present invention.

FIG. 3 is a refrigerant circuit diagram showing a configuration of a first outdoor unit.

FIG. 4 is a refrigerant circuit diagram showing a configuration of second and third outdoor units.

FIG. 5 is a flowchart showing a process of operation control based on oil temperature.

[Explanation of symbols]

 6 Concentration detection means 7 Control means 8 Concentration determination means 10 Air conditioner (refrigeration system) 21 Compression mechanism 70 Oil return mechanism (oil return means) 75 Oil level pipe (oil leveling means) Th51 Oil temperature sensor (oil temperature detection means) COMP -1 Upstream compressor (1st compressor) COMP-2 Downstream compressor (2nd compressor) To Oil temperature

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiichi Masashi 1304 Kanaoka-machi, Sakai City, Osaka Prefecture Daikin Industries, Ltd.Kanaoka Plant, Sakai Manufacturing Co., Ltd. (72) Akihiro Oka 1304, Kanaoka-machi, Sakai City, Osaka Daikin Industries, Ltd. Sakai Plant Kanaoka Factory

Claims (6)

[Claims] 1. A variable capacity compression mechanism (21) for sucking and compressing and discharging a mixed fluid formed by mixing lubricating oil with a refrigerant.
And an oil return means (70) for separating the lubricating oil from the mixed fluid discharged by the compression mechanism (21) and returning it to the suction side of the compression mechanism (21), Based on the concentration detecting means (6) for detecting the state of decrease in the concentration of the lubricating oil of the compression mechanism (21) due to the liquid refrigerant, and the state of decrease in the oil concentration detected by the concentration detecting means (6), the compression mechanism An operation control device for a refrigerating machine, comprising: a control means (7) for limiting the capacity of (21). 2. The operation control device for a refrigerating apparatus according to claim 1, wherein the compression mechanism (21) is composed of an inverter compressor whose capacity changes according to an input frequency, and the control means (7) comprises: By setting the upper limit frequency of the inverter compressor (21), the inverter compressor (21)
Is configured to limit the capacity of the refrigeration system. 3. A refrigeration system operation controller according to claim 1, wherein the compression mechanism (21) comprises a first compressor (COMP-1) and the first compressor (COMP-1).
The second with a larger pressure loss on the suction side than the compressor (COMP-1)
The compressor (COMP-2) is arranged in parallel, and the oil return means (70) is configured to return the separated lubricating oil to the suction side of the first compressor (COMP-1). According to the low pressure generated in the second compressor (COMP-2) due to the operation of the compressor (COMP-2), the first compressor (CO
An oil leveling means (75) for supplying the lubricating oil of MP-1) to the second compressor (COMP-2) is provided, and the control means (7) limits the operation of the second compressor (COMP-2). By so doing, the operation control device for the refrigeration system is configured so as to limit the capacity of the compression mechanism (21). 4. The operation control device for a refrigerating apparatus according to claim 3, wherein the first compressor (COMP-1) of the compression mechanism (21) is an inverter compressor that operates according to an input frequency. The control means (7) limits the capacity of the compression mechanism (21) by setting the upper limit frequency of the first compressor (COMP-1) in addition to the operation restriction of the second compressor (COMP-2). An operation control device for a refrigerating device, which is configured to be restricted. 5. The refrigeration system operation control device according to claim 1, wherein the concentration detecting means (6) includes an oil temperature detecting means (Th51) for detecting a temperature (To) of the lubricating oil of the compression mechanism (21). And a concentration determination means (8) for determining the state of decrease in the concentration of the lubricating oil due to the liquid refrigerant based on the temperature (To) of the lubricating oil detected by the oil temperature detection means (Th51). The means (8) is configured to determine that the decrease in the oil concentration is in progress when the temperature (To) of the lubricating oil detected by the oil temperature detecting means (Th51) is equal to or lower than a predetermined value. The control means (7) is configured to limit the capacity of the compression mechanism (21) when it is determined by the concentration determination means (8) that the oil concentration is decreasing. The operation control device for the refrigeration system. 6. The operation control device for a refrigerating apparatus according to claim 5, wherein the concentration determination means (8) includes an oil temperature detection means (after the capacity of the compression mechanism (21) is limited by the control means (7). When the temperature (To) of the lubricating oil detected by Th51) rises above a second predetermined value higher than the predetermined value, it is determined that the oil concentration has improved, and the control means (7) ) Is the compression mechanism (21) when the concentration determination means (8) determines that the oil concentration has improved.
An operation control device for a refrigerating apparatus, which is configured to release the capacity limitation of the above.