JP2016176664A - Refrigeration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration device which stores a proper amount of refrigeration machine oil in a compressor, and which can achieve improvement of performance by suppressing outflow into a refrigerant circuit.SOLUTION: A refrigeration device includes a compressor 11, an oil separator 21 connected to a discharge side of the compressor 11, and a first oil return pipeline 33 provided between the suction side of the compressor 11 and the oil separator 21 and for returning a refrigeration machine oil in the oil separator 21 to the compressor 11, and it performs a vapor compression type refrigeration cycle operation. The first oil return pipeline 33 includes an oil adjustment container 23 capable of storing oil, and a throttle member 24 for stabilizing an amount of the refrigeration machine oil in the compressor 11 at a predetermined amount by limiting a flow rate of the refrigeration machine oil returning to the compressor 11 from the oil adjustment container 23 at a constant rate.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a refrigeration apparatus such as an air conditioner.

  In a refrigeration apparatus such as an air conditioner that performs a vapor compression refrigeration cycle operation, refrigeration oil is enclosed in order to lubricate drive parts of a compressor that compresses refrigerant. A part of the refrigerating machine oil flows out into the refrigerant circuit together with the refrigerant discharged from the compressor. Most of the refrigeration oil that has flowed out is separated by the oil separator and returned to the compressor, but some of the refrigeration oil is circulated in the refrigerant circuit together with the refrigerant and then returned to the compressor. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 11-316058

The refrigerating machine oil in the compressor is encapsulated in a large amount assuming the maximum pipe length regardless of the actual refrigerant pipe length so that shortage does not occur even if it flows into the refrigerant circuit. Therefore, there may be a case where more refrigeration oil than the appropriate amount is stored in the compressor.
However, as the amount of the refrigerating machine oil in the compressor increases, it becomes easier to be discharged together with the refrigerant, and more refrigerating machine oil flows out into the refrigerant circuit. The refrigerating machine oil that has flowed out into the refrigerant circuit hinders heat exchange in a heat exchanger or the like, which may reduce the performance of the refrigeration apparatus.

  An object of the present invention is to provide a refrigeration apparatus capable of suppressing the outflow of refrigerating machine oil held in a compressor into a refrigerant circuit and improving performance.

(1) The refrigeration apparatus of the present invention is provided between a compressor, an oil separator connected to a discharge side of the compressor, and a suction side of the compressor and the oil separator. A first oil return pipe for returning the refrigeration oil in the container to the compressor, and a refrigeration apparatus that performs a vapor compression refrigeration cycle operation,
In the first oil return pipe,
An oil adjustment container capable of storing refrigerating machine oil;
There is provided a throttle member that stabilizes the amount of the refrigerating machine oil in the compressor to a predetermined amount by limiting the flow rate of the refrigerating machine oil returning from the oil adjusting container to the compressor.

According to said structure, since the oil adjustment container is provided in the 1st oil return piping, the surplus refrigeration oil in the middle of returning from an oil separator to a compressor can be stored in an oil adjustment container. Therefore, the surplus amount of refrigeration oil in the compressor can be reduced, the amount of refrigeration oil discharged from the compressor together with the refrigerant can be reduced as much as possible, and a decrease in heat exchange efficiency or the like can be suppressed.
On the other hand, the throttle member limits the flow rate of the refrigerating machine oil returning from the oil adjusting container to the compressor to a certain amount, and stabilizes the amount of the refrigerating machine oil in the compressor to a predetermined amount. For example, when an appropriate amount of refrigeration oil in the compressor is held, the squeezing member returns almost the same amount of refrigeration oil discharged from the compressor from the oil adjustment container to the compressor, It is possible to stabilize the refrigeration oil in an appropriate amount. When the amount of refrigerating machine oil held in the compressor is larger than the appropriate amount, the flow of refrigerating machine oil discharged from the compressor increases, but the refrigerating machine oil is returned from the oil adjustment container to the compressor at a flow rate limited by the capillary. By storing the surplus in the oil adjustment container, the refrigerating machine oil in the compressor can be stabilized to an appropriate amount. Conversely, if the amount of refrigerating machine oil held in the compressor is less than the appropriate amount, the flow rate of refrigerating machine oil discharged from the compressor will decrease, but in addition to the refrigerating machine oil discharged from the compressor, Since the refrigeration oil stored in the compressor can be returned to the compressor via the capillary, the refrigeration oil in the compressor can be gradually stabilized to an appropriate amount. Therefore, in the present invention, by providing the throttle member in the first oil return pipe, the amount of refrigerating machine oil in the compressor can be controlled at low cost without using an electrical component such as an on-off valve. Moreover, since parts with few failures etc. can be used as the diaphragm member, the reliability can be improved.
The predetermined amount for stabilizing the refrigerating machine oil may be one specific value or a range having a certain width. When the compressor is a variable capacity type (variable operating speed), the predetermined amount varies depending on the capacity (operating speed).

(2) A second oil return pipe is provided in parallel with the first oil return pipe between the oil adjustment container and the compressor, and the flow rate is adjusted in the second oil return pipe. It is preferable that a regulating valve is provided.
According to this configuration, for example, when the differential pressure between the upstream side and the downstream side of the throttle member is small and the refrigerating machine oil at a constant flow rate does not flow through the throttle member, or the refrigerating machine oil is unevenly distributed among a plurality of compressors. When it is desired to empty the oil adjusting container, all the refrigerating machine oil in the oil adjusting container can be discharged and returned to the compressor by opening the adjusting valve as necessary.
The regulating valve here is not limited to one that can adjust the flow rate steplessly or in multiple stages, but also includes one that simply opens and closes the second oil return pipe (an on-off valve that turns on and off the flow of the refrigeration oil). .

(3) The refrigeration apparatus may include a control unit that controls to open the adjustment valve when the differential pressure between the upstream side and the downstream side of the throttle member is equal to or less than a predetermined value.
When the differential pressure between the upstream side and the downstream side of the throttle member is less than or equal to a predetermined value, there is a possibility that the amount of refrigerating machine oil necessary to stabilize the refrigerating machine oil in the compressor to a predetermined amount cannot be returned to the compressor. There is. Therefore, in such a case, the regulating valve can be controlled so that the required amount of refrigeration oil returns to the compressor.

(4) It is preferable that the control unit performs control so as to open the adjustment valve when performing an oil return operation for returning the refrigeration oil to the compressor.
With such a configuration, when performing the oil return operation for returning the refrigeration oil existing in the refrigerant circuit to the compressor, the second refrigeration oil in the oil adjustment container is not affected by the restriction of the flow rate by the throttle member. It can be returned to the compressor via the oil return pipe.

  ADVANTAGE OF THE INVENTION According to this invention, the outflow to the refrigerant circuit of the refrigerating machine oil stored in the compressor can be suppressed, and a performance improvement can be aimed at.

It is a schematic block diagram of the air conditioning apparatus in one embodiment of this invention. It is a schematic block diagram which shows the principal part (compressor periphery) of an air conditioning apparatus in detail. It is a graph explaining the relationship between the oil level height of the refrigerating machine oil in a compressor, and an oil rising rate. It is a graph explaining the relationship between the rotation speed of a compressor, an oil rising rate, and resistance of a capillary. It is a graph explaining the relationship between the rotation speed of a compressor and the amount of refrigeration oil in a compressor, the oil adjustment container, and the piping of a refrigerant circuit.

FIG. 1 is a schematic diagram showing an air conditioner as a refrigeration apparatus according to an embodiment of the present invention.
The air conditioner 1 is a multi-type air conditioner for buildings, for example, and a refrigerant circuit 10 is formed so that a plurality of indoor units 3 are connected in parallel to a plurality of outdoor units 2 and refrigerant can flow. Has been.

  The outdoor unit 2 is provided with a compressor 11, a four-way switching valve 12, an outdoor heat exchanger 13, an outdoor expansion valve 14, an accumulator 20, an oil separator 21, and the like. These are connected by refrigerant piping. The outdoor unit 2 is provided with a blower fan 22. The indoor unit 3 is provided with an indoor expansion valve 15, an indoor heat exchanger 16, and the like.

  The four-way switching valve 12 and the indoor heat exchanger 16 are connected by a gas side refrigerant communication pipe 17a. The outdoor expansion valve 14 and the indoor expansion valve 15 are connected by a liquid side refrigerant communication pipe 17b. A gas side shut-off valve 18 and a liquid side shut-off valve 19 are provided at a terminal portion of the internal refrigerant circuit of the outdoor unit 2. The gas side closing valve 18 is arranged on the four-way switching valve 12 side, and the liquid side closing valve 19 is arranged on the outdoor expansion valve 14 side. A gas side refrigerant communication pipe 17 a is connected to the gas side shutoff valve 18, and a liquid side refrigerant communication pipe 17 b is connected to the liquid side shutoff valve 19.

  As shown also in FIG. 2, the oil separator 21 is provided in the discharge pipe 31 between the discharge side of the compressor 11 and the four-way switching valve 12. The oil separator 21 is connected to a suction pipe 32 that connects the four-way switching valve 12 and the suction side of the compressor 11 via a first oil return pipe 33.

  In the air conditioner 1 having the above-described configuration, when the cooling operation is performed, the four-way switching valve 12 is held in a state indicated by a solid line in FIG. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor 11 flows into the outdoor heat exchanger 13 through the oil separator 21 and the four-way switching valve 12, and is condensed by exchanging heat with outdoor air by the operation of the blower fan 22.・ Liquefy. The liquefied refrigerant passes through the fully-expanded outdoor expansion valve 14 and flows into each indoor unit 3 through the liquid side refrigerant communication pipe 17b. In the indoor unit 3, the refrigerant is decompressed to a predetermined low pressure by the indoor expansion valve 15, and further evaporates by exchanging heat with indoor air in the indoor heat exchanger 16. The room air cooled by the evaporation of the refrigerant is blown into the room by an indoor fan (not shown) to cool the room. The refrigerant evaporated and vaporized in the indoor heat exchanger 16 returns to the outdoor unit 2 through the gas side refrigerant communication pipe 17a, and is sucked into the compressor 11 through the four-way switching valve 12 and the accumulator 20.

  On the other hand, when the heating operation is performed, the four-way switching valve 12 is held in a state indicated by a broken line in FIG. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor 11 flows into the indoor heat exchanger 16 of each indoor unit 3 through the oil separator 21 and the four-way switching valve 12, and exchanges heat with indoor air to condense / Liquefaction. The indoor air heated by the condensation of the refrigerant is blown into the room by an indoor fan to heat the room. The refrigerant liquefied in the indoor heat exchanger 16 returns to the outdoor unit 2 through the liquid side refrigerant communication pipe 17b from the indoor expansion valve 15 whose opening degree is adjusted so as to achieve the target degree of supercooling. The refrigerant that has returned to the outdoor unit 2 is decompressed to a predetermined low pressure by the outdoor expansion valve 14, and further evaporates by exchanging heat with outdoor air in the outdoor heat exchanger 13. The refrigerant evaporated and vaporized in the outdoor heat exchanger 13 is sucked into the compressor 11 through the four-way switching valve 12 and the accumulator 20.

The compressor 11 is a variable capacity type, and the rotational speed of the motor is adjusted by inverter control. In addition, refrigeration oil for lubricating drive components is stored inside the compressor 11, and a small amount of this refrigeration oil is discharged from the compressor 11 together with the refrigerant. The discharged refrigerating machine oil is separated from the refrigerant in the oil separator 21 and returned to the suction side of the compressor 11 through the first oil return pipe 33.
The first oil return pipe 33 is provided with an oil adjustment container 23 and a capillary tube (throttle member) 24. The oil adjustment container 23 is configured to store refrigeration oil therein. The capillary tube 24 provides resistance to the refrigerating machine oil flowing through the first oil return pipe 33 and restricts the flow rate of the refrigerating machine oil flowing through the inside to be substantially constant. Further, a second oil return pipe 34 is provided between the oil adjustment container 23 and the suction pipe 32 in parallel with the first oil return pipe 33. The second oil return pipe 34 is provided with an electromagnetic valve (open / close valve) 26.

  The refrigerating machine oil separated by the oil separator 21 flows into the oil adjustment container 23 as it is, and is returned to the compressor 11 at a flow rate limited by the capillary tube 24. When the flow rate of the refrigerating machine oil flowing from the oil separator 21 into the oil adjustment container 23 is larger than the flow rate of the refrigerating machine oil flowing through the capillary tube 24, an amount of refrigerating machine oil corresponding to the flow rate difference is stored in the oil adjustment container 23. Is done. Conversely, when the flow rate of the refrigerating machine oil flowing from the oil separator 21 into the oil adjustment container 23 is smaller than the flow rate of the refrigerating machine oil flowing through the capillary tube 24, the refrigerating machine oil flowing into the oil adjustment container 23 from the oil separator 21 The entire amount is returned to the compressor 11, and the refrigeration oil originally stored in the oil separator 21 is also returned to the compressor 11. The amount of refrigerating machine oil flowing from the oil separator 21 into the oil regulating container 23 depends on the amount of refrigerating machine oil discharged from the compressor 11.

  FIG. 3 is a graph for explaining the relationship between the oil level height of the refrigeration oil in the compressor and the oil rising rate. The oil rising rate is the ratio of refrigerating machine oil contained in the refrigerant discharged from the compressor 11, and the higher the value, the larger the amount of refrigerating machine oil discharged from the compressor 11. According to FIG. 3, it can be seen that the oil rising rate increases as the oil level height of the refrigerating machine oil in the compressor 11 increases, that is, as the amount of refrigerating machine oil increases. Further, FIG. 3 shows the relationship between the amount of refrigerating machine oil and the oil rising rate for each of a plurality of rotation speeds. According to this, it turns out that there exists a tendency for oil rising rate to become high, so that rotation speed is high.

In the present embodiment, the flow rate (resistance) of the refrigerating machine oil limited by the capillary tube 24 can be set as follows, for example.
FIG. 4 is a graph for explaining the relationship among the rotational speed of the compressor, the oil rising rate, and the resistance of the capillary tube. In setting the resistance of the capillary tube 24, first, when the compressor 11 is operated at the rated rotational speed, the oil level height at which the lubrication in the compressor 11 is appropriately performed is defined as the “specified oil level height”. Set to. For example, as shown in FIG. 2, when the rated rotational speed is 140 rps, the oil level height at which the oil rising rate is 3% is set to the “specified oil level height”.

  Then, as shown in FIG. 4, when the compressor 11 is operated at the rated speed, the amount of refrigerating machine oil discharged from the compressor 11, that is, the amount of refrigerating machine oil discharged at an oil rising rate of 3% ( The resistance of the capillary tube 24 is selected so that the specified discharge oil amount) is directly returned from the oil adjustment container 23 to the compressor 11. Therefore, when the compressor 11 has a refrigeration oil having a specified oil level, the refrigeration oil in the compressor 11 is maintained at the specified oil level during operation at the rated speed. Become.

  When the refrigeration oil held in the compressor 11 exceeds the specified oil level height (see “oil level (high)” in FIG. 4), the compressor 11 is driven at the rated rotational speed and the oil exceeds 3%. The refrigerating machine oil is discharged at a rising rate and flows into the oil adjustment container 23. However, since only the refrigerating machine oil corresponding to the oil rising rate of 3% is returned to the compressor 11 by the capillary tube 24, the refrigerating machine oil held in the compressor 11 gradually decreases as shown by the arrow a in FIG. Stable at the specified oil level. The refrigerating machine oil that has not been returned to the compressor 11 is stored in the oil adjustment container 23.

  Therefore, even if the amount of refrigerating machine oil discharged from the compressor 11 is larger than the specified amount, the surplus can be stored in the oil adjustment container 23. Therefore, it is possible to prevent the refrigerating machine oil that has not been returned to the compressor 11 from being discharged into the refrigerant circuit 10, and to suppress a decrease in the performance of the refrigerating apparatus 1.

  Conversely, when the refrigeration oil held in the compressor 11 is less than the specified oil level (see “Oil level (low)” in FIG. 3), the oil rise rate is less than 3% when operated at the rated speed. The refrigeration oil is discharged and flows into the oil adjustment container 23. However, refrigeration oil corresponding to an oil rising rate of 3% including the refrigeration oil originally stored in the oil adjustment container 23 is returned from the oil adjustment container 23 to the compressor 11 through the capillary tube 24. That is, the amount of refrigerating machine oil that flows out from the refrigerating machine oil that flows into the oil adjustment container 23 increases. Therefore, as indicated by an arrow b in FIG. 3, the refrigeration oil held in the compressor 11 gradually increases and stabilizes at the specified oil level.

  Therefore, even if the amount of refrigeration oil in the compressor 11 is less than the specified amount, the amount of refrigeration oil can be increased to the specified oil level using the refrigeration oil in the oil adjustment container 23. Therefore, it is possible to prevent oil shortage during rated operation, increase the reliability of the compressor 11, and perform stable refrigeration cycle operation.

  On the other hand, a case where the compressor 11 is operated at a rotational speed lower than the rated rotational speed, for example, a case where the compressor 11 is operated at the rotational speed A in FIG. 4 will be described. When the amount of the refrigerating machine oil held in the compressor 11 is the specified oil level height, the compressor 11 discharges an amount of the refrigerating machine oil that is less than 3%. The refrigerating machine oil corresponding to the oil rising rate of 3% including the refrigerating machine oil stored in 23 is returned to the compressor 11. Therefore, the refrigerating machine oil held in the compressor 11 gradually increases and stabilizes at an oil level (oil level (high) in FIG. 3) higher than the specified oil level. In this case, more refrigeration oil than the specified oil level height during rated operation is retained in the compressor 11, but the amount of refrigeration oil discharged from the compressor 11 does not increase from during rated operation. The amount of refrigerant discharged into the refrigerant circuit 10 does not increase.

  The resistance of the capillary tube 24 is set in consideration of the differential pressure between the upstream side and the downstream side of the capillary tube 24 in the steady operation (cooling operation and heating operation) of the refrigeration apparatus 1. Specifically, the flow rate of the refrigerating machine oil returned from the oil adjustment container 23 to the compressor 11 is set to be larger than the flow rate of the refrigerating machine oil discharged from the compressor 11 under the condition of the lowest differential pressure in the steady operation. The

FIG. 5 is a graph for explaining the relationship between the rotation speed of the compressor and the amount of refrigeration oil in the compressor, the oil adjustment container, and the piping of the refrigerant circuit.
According to FIG. 5, in the region α where the rotational speed is low, the amount of refrigerating machine oil held in the compressor 11 increases, and conversely, the refrigerating machine oil storage amount in the oil adjustment container 23 and the refrigerating machine oil amount held in the piping There are few. Further, when the rotational speed is increased as in the region β, the amount of refrigerating machine oil discharged from the compressor 11 is increased, so that the amount held by the compressor 11 is decreased, but the refrigerating oil stored in the oil adjustment container 23 is reduced. The amount of machine oil increases and the amount of refrigeration oil discharged to the piping of the refrigerant circuit 10 does not increase so much. And in the area | region (gamma) where a rotation speed is high, the amount of refrigeration oil hold | maintained with the compressor 11, the oil adjustment container 23, and piping is stabilized.

As shown in FIG. 2, the electromagnetic valve 26 provided in the second oil return pipe 34 is closed during the steady operation of the refrigeration apparatus 1 and opened during a specific operation state. Thus, the refrigeration oil in the oil adjustment container 23 is returned to the compressor 11.
For example, when the differential pressure between the upstream side and the downstream side of the capillary tube 24 is equal to or less than a predetermined value and the refrigeration oil in the oil adjustment container 23 cannot be returned to the compressor 11 via the capillary tube 24, the electromagnetic valve 26 is turned on. Opening and refrigerating machine oil can be returned to the compressor 11 via the second oil return pipe 34.

The solenoid valve 26 is opened so that the oil in the compressor 11 does not run out even in the operation state other than the steady operation such as the start-up of the refrigeration apparatus 1, the defrost operation, or the oil return operation. The refrigerating machine oil in the adjustment container 23 can be returned to the compressor 11 via the second oil return pipe 34.
The oil return operation is, for example, an operation that is periodically performed in order to eliminate the bias of the refrigerating machine oil held in the compressor 11 between a plurality of outdoor units (an oil bias). By opening, all the refrigerating machine oil in the oil adjusting container 23 is discharged, and the refrigerating machine oil is evenly held in each compressor 11.

  The operation of the solenoid valve 26 is controlled by the control unit 40. In particular, when opening and closing the solenoid valve 26 according to the differential pressure between the upstream side and the downstream side of the capillary tube 24, the control unit 40 determines the upstream side pressure (discharge pressure of the compressor 11) and the downstream side of the capillary tube 24. The electromagnetic valve 26 can be controlled based on the detected values of the pressure sensors 28 and 29 (see FIG. 2) that measure the pressure (the suction pressure of the compressor 11).

The present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the invention described in the claims.
For example, the rotational speed of the rated operation described in the above embodiment, the oil rising rate as a reference for the specified oil level, and the like can be appropriately changed according to the type and installation status of the refrigeration apparatus 1. .

The electromagnetic valve 26 provided in the second oil return pipe 34 may be an adjustment valve capable of adjusting the flow rate of the refrigerating machine oil.
The configuration of the refrigerant circuit is not limited to the above embodiment. For example, another accessory device may be included in the refrigerant circuit.

  In the above embodiment, the pressure sensors 28 and 29 are used to measure the upstream pressure and the downstream pressure of the capillary tube 24. However, the condensation temperature in the condenser or the evaporation temperature in the evaporator is measured by the temperature sensor. The temperature may be converted into pressure.

  Although the outdoor heat exchanger 13 of the above embodiment is an air heat source type that exchanges heat with air, it may be a water heat source type that exchanges heat with water.

1: Air conditioner (refrigeration unit)
10: Refrigerant circuit 11: Compressor 21: Oil separator 23: Oil adjusting container 24: Capillary tube (throttle member)
26: Solenoid valve (regulating valve)
33: 1st oil return piping 34: 2nd oil return piping 40: Control part

Claims (4)

Provided between the compressor (11), the oil separator (21) connected to the discharge side of the compressor (11), and the suction side of the compressor (11) and the oil separator (21) And a first oil return pipe (33) for returning the refrigeration oil in the oil separator (21) to the compressor (11), and performing a vapor compression refrigeration cycle operation. Because
In the first oil return pipe (33),
An oil adjustment container (23) capable of storing oil;
A throttle member that stabilizes the amount of refrigerating machine oil in the compressor (11) to a predetermined amount by limiting the flow rate of refrigerating machine oil returning from the oil adjusting container (23) to the compressor (11) to a certain amount. 24).   Between the oil adjustment container (23) and the compressor (11), a second oil return pipe (34) is provided in parallel with the first oil return pipe (33). The refrigerating apparatus according to claim 1, wherein an adjustment valve (26) for adjusting a flow rate is provided in the oil return pipe (34).   The control part (40) which controls to open the said adjustment valve (26) when the differential pressure | voltage of the upstream and downstream of the said throttle member (24) is below a predetermined value is provided. The refrigeration apparatus described.   The said control part (40) is a freezing apparatus of Claim 2 controlled to open the said adjustment valve (26) when performing the oil return operation | movement which returns refrigerating machine oil to the said compressor (11).

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