JP2010071614A - Refrigerating device - Google Patents

Abstract

【Task】
An object is to obtain a refrigeration apparatus capable of satisfactorily supplying refrigeration oil to a compressor while improving the refrigeration capacity.
[Solution]
The refrigerating apparatus according to the present invention is a refrigerating apparatus including a refrigerating cycle configured by sequentially connecting a compressor 1, an oil separator 2, a condenser 3, a pressure reducing mechanism 7, and an evaporator 8. A liquid refrigerant cooling circuit 15 and an intermediate pressure liquid injection circuit 16 for injecting a part of the high-pressure refrigerant circulating in the main circuit of the cycle and extracting the reduced pressure refrigerant into the intermediate pressure part of the compressor 1, and the oil separator 2 An intermediate pressure oil return circuit 13 that returns the refrigeration oil separated in step 1 to the intermediate pressure portion of the compressor 1, and a suction portion oil return circuit 14 that returns the refrigeration oil separated in the oil separator 2 to the suction portion of the compressor 1. And a state in which the refrigeration oil is returned to the intermediate pressure part by the intermediate pressure oil return circuit 13 and a state in which the refrigerating machine oil is returned to the suction part by the suction part oil return circuit 14 can be selected.
[Selection] Figure 1

Description

  In a refrigeration apparatus having a refrigeration cycle configured by sequentially connecting a compressor, a condenser, a decompression mechanism, and an evaporator, refrigeration oil contained in high-pressure refrigerant compressed by the compressor is separated in an oil separator, and the compressor The present invention relates to a refrigeration apparatus that is returned to

  Conventionally, refrigeration oil has been used to lubricate the inside of a compressor in a refrigeration apparatus. In the compression process in the compressor, not only the refrigerant but also the refrigerating machine oil is discharged to the high pressure side, so that oil rises.

  Therefore, in the refrigeration apparatus, in order to prevent the oil from rising from the compressor, an oil separator is arranged on the discharge side of the compressor, and the refrigerating machine oil is separated from the discharge gas refrigerant compressed by the oil separator. It is configured to return to the compressor.

  For example, in the refrigeration apparatus shown in Patent Document 1, an oil return circuit from the oil separator is connected to the suction side of the compressor. This oil return circuit is provided with an electromagnetic valve as an on-off valve. By opening and closing the electromagnetic valve, the refrigeration oil returns to the suction portion of the compressor.

  However, in the refrigeration apparatus shown in Patent Document 1, the high-temperature refrigeration oil separated by the oil separator is returned to the suction portion of the compressor, so that the suction refrigerant gas temperature of the compressor rises and the specific volume increases. End up. Therefore, the amount of refrigerant sucked into the compressor is reduced by the amount of the refrigerating machine oil, and the refrigerant circulation amount is reduced, so that there is a problem that the refrigerating capacity is lowered.

  In order to solve this problem, for example, a refrigeration apparatus shown in Patent Document 2 includes an intermediate pressure oil return circuit that returns refrigeration oil to an intermediate pressure portion of a compressor.

  In addition, the refrigeration system compresses the decompressed refrigerant that has been decompressed by extracting a portion of the high-pressure refrigerant that circulates through the main circuit of the refrigeration cycle in order to stabilize the operation of the compressor and improve the refrigeration capacity. Some have an intermediate pressure refrigerant introduction circuit that is injected into the intermediate pressure portion of the machine. For example, in the refrigeration apparatus shown in Patent Document 2, as the intermediate pressure refrigerant introduction circuit, the decompressed refrigerant extracted from the main circuit of the refrigeration cycle and decompressed is heated in the high-pressure refrigerant circulating in the main circuit and the supercooling heat exchanger. After the replacement, a liquid refrigerant cooling circuit for injecting the intermediate pressure portion of the compressor is provided. The refrigeration apparatus is configured to perform the liquid refrigerant cooling circuit and the intermediate pressure oil return circuit simultaneously.

International Publication No. 03/083380 Pamphlet JP 2007-178052 A

  By the way, when an intermediate-pressure refrigerant introduction circuit and an intermediate-pressure oil return circuit are provided in the refrigeration apparatus and the refrigerant injection and the refrigerating machine oil injection are performed simultaneously with respect to the intermediate pressure portion of the compressor, depending on the pressure difference, There may be a case where the refrigerating machine oil cannot be injected well into the pressure section. In this case, the refrigerating machine oil in the compressor is insufficient, and the compressor may be damaged.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to obtain a refrigeration apparatus that can supply refrigeration oil well to a compressor while improving the refrigerating capacity.

  The refrigeration apparatus according to the present invention includes a compressor, an oil separator for separating refrigeration oil contained in the high-pressure refrigerant compressed by the compressor, and a condensation for condensing the high-pressure refrigerant separated by the oil separator. In a refrigeration apparatus comprising a refrigeration cycle configured by sequentially connecting a condenser, a decompression mechanism that decompresses the high-pressure refrigerant condensed in the condenser, and an evaporator that evaporates the low-pressure refrigerant decompressed by the decompression mechanism, An intermediate-pressure refrigerant introduction circuit that injects a part of the high-pressure refrigerant circulating through the main circuit of the refrigeration cycle to inject the reduced-pressure refrigerant into the intermediate pressure part of the compressor, and compresses the refrigeration oil separated by the oil separator An intermediate pressure oil return circuit for returning to the intermediate pressure part of the machine, and a suction part oil return circuit for returning the refrigeration oil separated by the oil separator to the suction part of the compressor. Return to the intermediate pressure section and suction The parts oil return circuit, characterized in that it is configured to select the state to return to the suction unit.

  According to the above configuration, when the refrigerating machine oil can be returned to the intermediate pressure portion of the compressor, the refrigerating machine oil can be supplied into the compressor while exhibiting a high refrigerating capacity, and the refrigerating machine oil can be supplied. Even if it is impossible to return to the intermediate pressure part, it is possible to prevent the refrigerating machine oil from being insufficient in the compressor by returning the refrigerating machine oil to the suction part of the compressor.

  Further, in the refrigeration apparatus, there is a configuration in which the refrigeration oil is controlled to be injected into the intermediate pressure portion of the compressor while the operation of injecting the reduced-pressure refrigerant into the intermediate pressure portion of the compressor is stopped. preferable.

  If it does in this way, while the operation | movement which inject | pours a decompression refrigerant | coolant into the intermediate pressure part of a compressor is stopped, refrigerating machine oil can be supplied in a compressor, exhibiting high refrigerating capacity.

  In the refrigeration apparatus, the intermediate pressure refrigerant introduction circuit preferably includes an intermediate pressure injection circuit that bypasses the evaporator and is connected to a compressor.

  If it does in this way, the discharge temperature of a compressor can be stabilized by adjusting the opening of an intermediate pressure injection circuit.

  Further, in the refrigeration apparatus, as the intermediate pressure refrigerant introduction circuit, the decompressed refrigerant extracted from the main circuit of the refrigeration cycle and depressurized is heated in the high-pressure refrigerant circulating in the main circuit and the supercooling heat exchanger. A configuration including a liquid refrigerant cooling circuit that is injected into the intermediate pressure portion of the compressor after the replacement is preferable.

  In this way, the refrigerating capacity can be improved.

  Further, in the refrigeration apparatus, both the above-described circuits, that is, the intermediate pressure refrigerant introduction circuit, an intermediate pressure injection circuit that bypasses the evaporator and is connected to the compressor, and a main circuit of the refrigeration cycle. A configuration comprising a liquid refrigerant cooling circuit that heat-exchanges the extracted and decompressed refrigerant with the high-pressure refrigerant circulating in the main circuit and then injects it into the intermediate pressure portion of the compressor is preferable.

  Moreover, in the said refrigeration apparatus, the structure by which the said intermediate pressure refrigerant introduction circuit is connected to the intermediate pressure part of a compressor by the same piping as an intermediate pressure oil return circuit is preferable.

  In this way, the piping structure of the refrigeration apparatus can be simplified.

  Further, in the refrigeration apparatus, on the downstream side of the condenser, a liquid receiver that stores the refrigerant condensed in the condenser, and air that supercools the refrigerant discharged from the liquid receiver by heat exchange with air. A configuration in which the supercooling heat exchanger is arranged is preferable.

  In this way, it is possible to prevent flushing of the liquid refrigerant that leaves the condenser and is sent downstream.

  Further, the refrigeration apparatus according to the present invention condenses a compressor, an oil separator for separating refrigeration oil contained in the high-pressure refrigerant compressed by the compressor, and the high-pressure refrigerant separated by the oil separator. A refrigerating apparatus having a refrigeration cycle configured by sequentially connecting a condenser that depressurizes, a decompression mechanism that decompresses the high-pressure refrigerant condensed in the condenser, and an evaporator that evaporates the low-pressure refrigerant decompressed by the decompression mechanism In the compressor, after a part of the high-pressure refrigerant circulating in the main circuit of the refrigeration cycle is extracted and depressurized, heat is exchanged between the high-pressure refrigerant circulating in the main circuit and the supercooling heat exchanger. Liquid refrigerant cooling circuit to be injected into the intermediate pressure part, intermediate pressure oil return circuit for returning the refrigeration oil separated by the oil separator to the intermediate pressure part of the compressor, and compression of the refrigeration oil separated by the oil separator Suction part oil returned to the suction part of the machine And the operation of injecting the reduced-pressure refrigerant into the intermediate pressure part of the compressor is stopped, and after the refrigerating machine oil is injected into the intermediate pressure part of the compressor, the operation of injecting the refrigerating machine oil is stopped, The decompressed refrigerant is controlled to be injected into an intermediate pressure portion of the compressor.

  In this way, while the liquid refrigerant cooling circuit is closed and the reduced-pressure refrigerant is being injected into the intermediate pressure portion of the compressor, only the refrigerant can be drawn from the suction portion of the compressor, and the refrigerating capacity can be increased. Can be improved. Moreover, since the refrigeration oil is injected into the compressor at the previous stage, it is possible to operate with high refrigeration capacity without causing oil shortage.

  Further, the refrigeration apparatus according to the present invention condenses a compressor, an oil separator for separating refrigeration oil contained in the high-pressure refrigerant compressed by the compressor, and the high-pressure refrigerant separated by the oil separator. A refrigeration apparatus comprising a refrigeration cycle configured by sequentially connecting a condenser for reducing pressure, a decompression mechanism for decompressing the high-pressure refrigerant condensed in the condenser, and an evaporator for evaporating the low-pressure refrigerant decompressed by the decompression mechanism An intermediate pressure injection circuit for extracting a part of the high pressure refrigerant circulating through the main circuit of the refrigeration cycle and injecting the reduced pressure refrigerant into the intermediate pressure part of the compressor, and the high pressure refrigerant circulating through the main circuit of the refrigeration cycle The reduced-pressure refrigerant extracted from a part of the reduced-pressure refrigerant is heat-exchanged in the supercooling heat exchanger with the high-pressure refrigerant circulating in the main circuit, and then injected into the intermediate pressure portion of the compressor, oil An intermediate pressure oil return circuit for returning the refrigeration oil separated by the separator to the intermediate pressure part of the compressor, and an intake part oil return circuit for returning the refrigeration oil separated by the oil separator to the suction part of the compressor The intermediate pressure injection circuit and the liquid refrigerant cooling circuit are connected to the intermediate pressure portion of the compressor through the same piping as the intermediate pressure oil return circuit.

  In this way, while the discharge temperature of the compressor is stabilized by the intermediate pressure injection circuit, the refrigeration capacity can be improved by the liquid refrigerant cooling circuit, and moreover, by the intermediate pressure oil return circuit and the suction part oil return circuit. Further, it is possible to prevent a shortage of refrigerating machine oil in the compressor while exhibiting a high refrigerating capacity.

  As described above, according to the present invention, it is possible to obtain a refrigeration apparatus capable of satisfactorily supplying refrigeration oil to a compressor while improving the refrigeration capacity.

  FIG. 1 is a diagram illustrating a refrigeration cycle configuration of a refrigeration apparatus according to an embodiment of the present invention.

  The refrigeration apparatus according to this embodiment includes a compressor 1, an oil separator 2 for separating refrigeration oil contained in the high-pressure refrigerant compressed by the compressor 1, and a high pressure separated by the oil separator 2. A condenser 3 that condenses the refrigerant, a decompression mechanism 7 that decompresses the high-pressure refrigerant condensed in the condenser 3, and an evaporator 8 that evaporates the low-pressure refrigerant decompressed by the decompression mechanism 7 are connected in order. The main circuit of the cycle is configured.

  As shown in FIG. 1, the refrigeration apparatus accommodates a high-pressure side device I in which a compressor 1, an oil separator 2, a condenser 3 and the like, a decompression mechanism 7, an evaporator 8 and the like are accommodated. It consists of the high-pressure side equipment II.

  The compressor 1 compresses a low-pressure and low-temperature gas refrigerant into a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant compressed by the compressor 1 contains refrigeration oil. Therefore, the oil separator 2 separates the refrigerant and the refrigerating machine oil. The high-temperature and high-pressure gas refrigerant separated by the oil separator 2 is condensed by the condenser 3 to become a high-temperature and high-pressure liquid refrigerant. The condensed high-pressure liquid refrigerant is decompressed by the decompression mechanism 7 and evaporated by the evaporator 8 to return to the compressor 1 as a low-temperature and low-pressure gas refrigerant.

  In addition, as the compressor 1, a variable capacity type compressor with a variable driving frequency is used. Thereby, according to the load of a refrigerating cycle, a capacity variable type compressor can be controlled and a refrigerating capacity can be adjusted. Moreover, as the compressor 1, what is called a scroll compressor is used, However, It is not limited to this. Further, instead of a variable capacity compressor, a fixed capacity compressor (for example, a constant speed compressor) may be used. Further, the compressor may be a single unit or a plurality of units, and when a plurality of compressors are used, all may be variable capacity type compressors or fixed capacity type compressors, A combination of a variable capacity compressor and a fixed capacity compressor may be used.

  As the refrigerant, an HFC-based refrigerant (for example, R404-A or R410-A) is used.

  A liquid receiver 4 that stores the refrigerant condensed in the condenser 3 is disposed downstream of the condenser 3. Further, on the downstream side of the liquid receiver 4, an air supercooling heat exchanger 5 is provided that supercools the refrigerant discharged from the liquid receiver 4 by exchanging heat with air. Thereby, generation | occurrence | production of the bubble in the pipe line to the evaporator 8 (what is called generation | occurrence | production of flushing) can be prevented suitably. As a result, the fluctuation | variation of the refrigerant | coolant flow volume introduce | transduced into the supercooling heat exchanger 6 mentioned later can be suppressed, and refrigerating capacity can be stabilized.

  The main circuit of the refrigeration cycle includes a supercooling heat exchanger 6 for exchanging heat between the decompressed refrigerant extracted from the high-pressure refrigerant circulating in the main circuit and decompressed, and the high-pressure refrigerant circulating in the main circuit. Is arranged. The supercooling heat exchanger 6 is disposed on the downstream side of the condenser 3. Further, the supercooling heat exchanger 6 is disposed downstream of the liquid receiver 4 and the air supercooling heat exchanger 5. By the way, the high-pressure refrigerant heat-exchanged by the supercooling heat exchanger 6 is extracted from between the condenser 3 and the supercooling heat exchanger 6, specifically, the air supercooling heat exchanger 5 and the supercooling heat exchanger 6. It is extracted from between the cooling heat exchanger 6. However, it is not limited to this, and it may be extracted from the liquid receiver 4 or may be extracted from the downstream side of the supercooling heat exchanger 6.

  The refrigeration apparatus includes an intermediate pressure oil return circuit 13 that returns the refrigeration oil separated by the oil separator 2 to the intermediate pressure portion of the compressor 1, and the refrigeration oil separated by the oil separator 2 as a compressor. And a suction part oil return circuit 14 for returning to the first suction part. These oil return circuits 13 and 14 are drawn out from the oil separator 2 by the same pipe, and are branched to different pipes at a branch point before the compressor 1.

  The intermediate pressure oil return circuit 13 is provided with a valve 10 that controls injection of refrigeration oil into the intermediate pressure portion of the compressor 1. The valve 10 is arranged in a pipe from the branch point to the intermediate pressure part. This valve 10 is an on-off valve that switches between an open state and a closed state. However, the valve 10 is not limited to this, and may be constituted by a flow rate adjusting valve whose opening degree can be adjusted. In this case, the valve 10 is closed by fully closing it. It is said.

  The suction part oil return circuit 14 is provided with a valve 11 that controls injection of refrigerating machine oil into the suction part of the compressor 1. The valve 11 is arranged in a pipe from the branch point to the suction part. The valve 11 is provided as a pressure reducing adjustment valve, and specifically includes a combination of an on-off valve that switches between an open state and a closed state and an expansion valve (such as a capillary tube). More specifically, the suction part oil return circuit 14 is connected in parallel with a plurality of valves 11 each composed of an on-off valve and an expansion valve, and the number of the valves 11 that are open or closed is changed. By doing so, the flow rate can be adjusted. However, the valve 11 is not limited to this, and may be constituted by an electromagnetic expansion valve whose opening degree can be adjusted. In this case, the valve 11 is closed by fully closing it. It is said.

  Each oil return circuit 13, 14 is provided with an oil cooling heat exchanger (not shown). As the oil cooling heat exchanger, a plate heat exchanger that exchanges heat with a liquid refrigerant or an air heat exchanger can be used. Since the low-temperature refrigeration oil can be returned to the intermediate pressure portion of the compressor 1 by the oil cooling heat exchanger, the pressure of the gas refrigerant compressed by the compressor 1 can be reduced. Moreover, since the temperature of the compressor 1 itself can be lowered, the reliability of the compressor 1 can be improved.

  Further, the refrigeration apparatus is provided with an intermediate pressure refrigerant introduction circuit that injects a part of the high-pressure refrigerant circulating in the main circuit of the refrigeration cycle and decompresses the reduced-pressure refrigerant into the intermediate pressure portion of the compressor 1. As the intermediate pressure refrigerant introduction circuit, there is provided a liquid refrigerant cooling circuit 15 for injecting the reduced pressure refrigerant heat-exchanged with the high-pressure refrigerant circulating in the main circuit in the supercooling heat exchanger 6 into the intermediate pressure portion of the compressor 1. ing. Further, as the intermediate pressure refrigerant introduction circuit, an intermediate pressure injection circuit 16 that bypasses the evaporator 8 and is connected to the compressor 1 is also provided.

  The liquid refrigerant cooling circuit 15 is provided with a valve 9 that controls injection of refrigeration oil into the intermediate pressure portion of the compressor 1. The valve 9 is provided as a pressure reducing valve, and specifically includes a combination of an on-off valve that switches between an open state and a closed state and an expansion valve (such as a capillary tube). However, the valve 9 is not limited to this, and may be constituted by an electromagnetic expansion valve whose opening degree can be adjusted. In this case, the valve 9 is closed by fully closing it. It is said.

  The valve 9 of the liquid refrigerant cooling circuit 15 is disposed between the branch point from the main circuit and the supercooling heat exchanger 6. However, when a combination of an on-off valve and an expansion valve is used as the valve 9 of the liquid refrigerant cooling circuit 15, only the expansion valve may be disposed upstream of the supercooling heat exchanger 6. It may be arranged downstream from the cooling heat exchanger 6.

  The intermediate pressure injection circuit 16 is provided with a valve 12 that controls injection of refrigeration oil into the intermediate pressure portion of the compressor 1. The valve 12 is provided as a pressure reducing adjustment valve, and is specifically configured by combining an on-off valve that switches between an open state and a closed state and an expansion valve (such as a capillary tube). However, the valve 12 is not limited to this, and may be constituted by an electromagnetic expansion valve whose opening degree can be adjusted. In this case, the valve 12 is closed by fully closing it. It is said.

  The valve 12 of the intermediate pressure injection circuit 16 is arranged between the branch point from the main circuit and the junction point with one of the liquid refrigerant cooling circuit 15 and the intermediate pressure oil return circuit 13 on the front side. Is done. When at least one of the intermediate pressure injection circuit 16 and the liquid refrigerant cooling circuit 15 is connected to the intermediate pressure portion of the compressor 1 through the same pipe as the intermediate pressure oil return circuit, the valve 12 The refrigerant cooling circuit 15 or the intermediate pressure oil return circuit 13 is disposed before the junction with the circuit.

  In the refrigeration apparatus, the intermediate pressure injection circuit 16 and the liquid refrigerant cooling circuit 15 are connected to the intermediate pressure portion of the compressor 1 through the same pipe as the intermediate pressure oil return circuit 13. Specifically, the intermediate pressure oil return circuit 13 further joins downstream from the joining point of the intermediate pressure injection circuit 16 and the liquid refrigerant cooling circuit 15. However, it is not limited to this, and the order of merging of the intermediate pressure injection circuit 16 and the liquid refrigerant cooling circuit 15 may be reversed.

  Note that at least one of the intermediate pressure injection circuit 16 and the liquid refrigerant cooling circuit 15 may be connected to the intermediate pressure portion of the compressor 1 through the same pipe as the intermediate pressure oil return circuit 13. In this case, any one of these three circuits 13, 15, 16 that does not merge with the other two circuits is connected to the intermediate pressure section of the compressor 1 separately from the other two circuits. Further, these three circuits 13, 15, and 16 may be separately connected to the intermediate pressure portion of the compressor 1.

  Further, on the discharge side of the compressor 1, a detection unit that detects the state of the refrigerant gas such as the discharge temperature is disposed.

  Moreover, the control part 18 which controls each said valves 9-12 is provided in the freezing apparatus. The control unit 18 controls the valves 9 to 12 based on the state of the refrigerant gas such as the discharge temperature detected by the detection unit.

  Next, operation | movement of the freezing apparatus which has the said structure is demonstrated using FIG. Although FIG. 2 illustrates the operation in time series, the length of time on the horizontal axis and the size of each quantity on the vertical axis are partially emphasized to make the contents of the control easier to understand. It is represented.

  As shown in FIG. 2, the refrigeration apparatus is initially stopped. Then, the refrigeration apparatus is started at time T1. At this time, the intermediate pressure injection circuit 16 and the suction part oil return circuit 14 are opened. Then, the discharge gas temperature rises and refrigeration capacity is generated. The intermediate pressure injection circuit 16 finely adjusts the injection amount by adjusting the opening of the valve 12 in order to stabilize the discharge gas temperature. This state is the normal operation control mode P1.

  When it is desired to increase the refrigerating capacity, the control mode P2 starts from time T2. Specifically, the valve 9 is opened and the liquid refrigerant cooling circuit 15 is opened.

  If it is desired to further increase the refrigeration capacity, the control mode P3 starts at time T3. In order to actually increase the refrigeration capacity, preparation is required in the previous stage, and the control mode P3 is a control mode for preparing (first and second preparation control modes P3- described later). 1, P3-2) and high-capacity control mode P3-3 in which high refrigeration capacity is exhibited.

  Specifically, the high capacity control mode P3-3 is a mode in which a high refrigerating capacity is exhibited by injecting only the refrigerant without injecting the refrigerating machine oil. Therefore, in the control mode in which preparation is performed, refrigerating machine oil to be sent to the discharge side during the high capacity control mode P3-3 is secured.

  The control mode in which preparation is performed is classified into a first preparation control mode P3-1 and a second preparation control mode P3-2. In the first preparation control mode P3-1, cooling (cooling) for efficiently returning the refrigeration machine oil is performed in the next second preparation control mode P3-2. Specifically, the intermediate pressure injection circuit 16 is fully opened at time T3. Then, the discharge gas temperature starts to decrease. The first preparation control mode P3-1 is performed for about 1 to 2 minutes. In the first preparation control control mode P3-1, the volume efficiency is lowered by increasing the amount of refrigerant injected at intermediate pressure, so that the refrigeration capacity is slightly lowered.

  When the discharge gas temperature decreases to a predetermined temperature (time T4), the process proceeds to the second preparation control mode P3-2. Specifically, at time T3, the intermediate pressure injection circuit 16, the liquid refrigerant cooling circuit 15, and the suction part oil return circuit 14 are closed, and the intermediate pressure oil return circuit 13 is opened. Thereby, refrigeration oil can be satisfactorily returned to the intermediate pressure part of the compressor 1. In the second preparation control mode P3-2, since the liquid refrigerant cooling circuit 15 is closed, the refrigerating capacity is reduced. The second preparation control mode P3-2 is performed for about 30 seconds to about 1 minute.

  Thereafter, at time T5, the process shifts to the high capacity control mode P3-3. In the high capacity control mode P3-3, the intermediate pressure injection circuit 16 and the liquid refrigerant cooling circuit 15 are opened, and the intermediate pressure oil return circuit 13 is closed. At this time, since the suction part oil return circuit 14 and the intermediate pressure oil return circuit 13 are closed, only the refrigerant can be sucked from the suction part of the compressor 1, and the refrigerating capacity is improved. The high-capacity control mode P3-3 is performed for a longer time than the first and second preparation control modes P3-1 and P3-2. Then, an integrated amount of the refrigerating capacity that is larger than the integrated amount of the refrigerating capacity decreased between the first and second preparation control modes P3-1 and P3-2 is obtained. Capability is improved over P2. In the high capacity control mode P3-3, the discharge gas temperature decreases.

  However, since the refrigeration oil is not supplied during the high capacity control mode P3-3, there is a limit to the operation in this mode. In order to continue the operation with a high refrigerating capacity, it is necessary to supply refrigerating machine oil to the compressor 1 again. Therefore, at the time T6, the process returns to the second preparation control mode P3-2. After that, at time T7, the high capacity control mode P3-3 is restored.

  As described above, according to the refrigeration apparatus according to the present embodiment, refrigeration capable of satisfactorily supplying refrigeration oil to the compressor 1 while improving refrigeration capacity and improving energy efficiency (COP). A device can be obtained.

  That is, according to the refrigeration apparatus having the above configuration, when the refrigeration oil can be returned to the intermediate pressure portion of the compressor 1, the refrigeration oil is supplied into the compressor 1 while exhibiting a high refrigeration capacity. Even if it is possible to return the refrigerating machine oil to the intermediate pressure part, it is possible to prevent the refrigerating machine oil from being insufficient in the compressor by returning the refrigerating machine oil to the suction part of the compressor 1. be able to.

  Further, since the refrigeration oil is controlled to be injected into the intermediate pressure portion of the compressor 1 while the operation of injecting the reduced pressure refrigerant into the intermediate pressure portion of the compressor is stopped, the reduced pressure refrigerant is supplied to the compressor. While the operation of injecting into the intermediate pressure part 1 is stopped, the refrigerating machine oil can be supplied into the compressor 1 while exhibiting a high refrigerating capacity.

  The refrigeration apparatus includes an intermediate pressure injection circuit 16, a liquid refrigerant cooling circuit 15, an intermediate pressure oil return circuit 13, and a suction part oil return circuit 14. Therefore, while the discharge pressure of the compressor 1 is stabilized by the intermediate pressure injection circuit 16, the refrigeration capacity can be improved by the liquid refrigerant cooling circuit 15, and the intermediate pressure oil return circuit 13 and the suction part oil return circuit 14 can be improved. Therefore, it is possible to prevent the refrigerating machine oil in the compressor 1 from being insufficient while exhibiting a high refrigerating capacity. Further, in this refrigeration apparatus, the intermediate pressure injection circuit 16 and the liquid refrigerant cooling circuit 15 are connected to the intermediate pressure portion of the compressor 1 through the same pipe as the intermediate pressure oil return circuit 13. Therefore, the piping structure of the refrigeration apparatus can be simplified.

  In addition, this refrigeration apparatus stops the operation of injecting the refrigerating machine oil after injecting the refrigerating machine oil into the intermediate pressure part of the compressor 1 by stopping the operation of injecting the reduced pressure refrigerant into the intermediate pressure part of the compressor 1. Thus, the decompressed refrigerant is controlled to be injected into the intermediate pressure portion of the compressor 1. Therefore, while the liquid refrigerant cooling circuit 15 is closed and the decompressed refrigerant is injected into the intermediate pressure portion of the compressor 1, only the refrigerant can be sucked from the suction portion of the compressor 1, thereby improving the refrigerating capacity. Can be made. Moreover, since the refrigeration oil is injected into the compressor 1 in the previous stage, it is possible to operate with a high refrigeration capacity without causing oil shortage.

  The refrigeration apparatus according to the present invention is not limited to the configuration of each of the above embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, in the above-described embodiment, the intermediate pressure injection circuit 16 and the liquid refrigerant cooling circuit 15 are provided as the intermediate pressure refrigerant introduction circuit. However, the present invention is not limited to this, and only one of them is provided. It may be provided.

  Moreover, although the intermediate pressure oil return circuit 13 and the suction part oil return circuit 14 have been described as being provided with separate valves 10 and 11, respectively, the present invention is not limited to this. For example, a valve such as a three-way valve may be arranged at a branch point of the intermediate pressure oil return circuit and the suction part oil return circuit.

It is a figure which shows the refrigerating cycle structure of the freezing apparatus which concerns on embodiment of this invention. It is a time chart which shows control of the refrigerating device concerning the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Oil separator 3 Condenser 4 Receiver 5 Air supercooling heat exchanger 6 Supercooling heat exchanger 7 Decompression mechanism 8 Evaporator 9, 10, 11, 12 Valve 13 Intermediate pressure oil return circuit 14 Suction part Oil return circuit 15 Liquid refrigerant cooling circuit 16 Intermediate pressure liquid injection circuit 17 Cooling fan 18 Control unit

Claims (9)

A compressor, an oil separator for separating refrigeration oil contained in the high-pressure refrigerant compressed by the compressor, a condenser for condensing the high-pressure refrigerant separated by the oil separator, and condensation by the condenser In a refrigeration apparatus comprising a refrigeration cycle configured by sequentially connecting a decompression mechanism for decompressing the high-pressure refrigerant and an evaporator for evaporating the low-pressure refrigerant decompressed by the decompression mechanism,
An intermediate pressure refrigerant introduction circuit that injects a reduced pressure refrigerant extracted from the high pressure refrigerant circulating through the main circuit of the refrigeration cycle into the intermediate pressure portion of the compressor;
An intermediate pressure oil return circuit for returning the refrigeration oil separated by the oil separator to the intermediate pressure portion of the compressor;
A suction section oil return circuit for returning the refrigeration oil separated by the oil separator to the suction section of the compressor;
A refrigeration apparatus configured to be able to select a state in which the refrigeration oil is returned to the intermediate pressure part by the intermediate pressure oil return circuit and a state in which the refrigerating machine oil is returned to the suction part by the suction part oil return circuit.   The refrigeration oil is controlled to be injected into the intermediate pressure portion of the compressor while the operation of injecting the reduced-pressure refrigerant into the intermediate pressure portion of the compressor is stopped. Refrigeration equipment.   The refrigeration apparatus according to claim 1, further comprising an intermediate pressure injection circuit that bypasses the evaporator and is connected to a compressor as the intermediate pressure refrigerant introduction circuit.   As the intermediate pressure refrigerant introduction circuit, the decompressed refrigerant extracted from the main circuit of the refrigeration cycle and decompressed is subjected to heat exchange with a high pressure refrigerant circulating in the main circuit in a supercooling heat exchanger, and then the compressor The refrigeration apparatus according to claim 1, further comprising a liquid refrigerant cooling circuit that is injected into the intermediate pressure unit. As the intermediate pressure refrigerant introduction circuit, an intermediate pressure injection circuit that bypasses the evaporator and is connected to a compressor;
A liquid refrigerant cooling circuit that heat-exchanges the decompressed refrigerant extracted from the main circuit of the refrigeration cycle and decompressed with a high-pressure refrigerant circulating in the main circuit, and then injects the refrigerant into an intermediate pressure portion of the compressor. The refrigeration apparatus according to claim 1 or 2, wherein   The refrigeration apparatus according to any one of claims 1 to 5, wherein the intermediate pressure refrigerant introduction circuit is connected to an intermediate pressure portion of the compressor through the same pipe as the intermediate pressure oil return circuit.   On the downstream side of the condenser, a liquid receiver that stores the refrigerant condensed in the condenser, and an air supercooling heat exchanger that supercools the refrigerant discharged from the liquid receiver by exchanging heat with air are arranged. The refrigeration apparatus according to any one of claims 1 to 6, wherein: A compressor, an oil separator for separating refrigeration oil contained in the high-pressure refrigerant compressed by the compressor, a condenser for condensing the high-pressure refrigerant separated by the oil separator, and condensation by the condenser In a refrigeration apparatus having a refrigeration cycle configured by sequentially connecting a decompression mechanism for decompressing the high-pressure refrigerant and an evaporator for evaporating the low-pressure refrigerant decompressed by the decompression mechanism,
After the reduced pressure refrigerant extracted from the high pressure refrigerant circulating in the main circuit of the refrigeration cycle and depressurized is heat-exchanged in the supercooling heat exchanger with the high pressure refrigerant circulating in the main circuit, the intermediate pressure of the compressor A liquid refrigerant cooling circuit to be injected into the unit,
An intermediate pressure oil return circuit for returning the refrigeration oil separated by the oil separator to the intermediate pressure portion of the compressor;
A suction section oil return circuit for returning the refrigeration oil separated by the oil separator to the suction section of the compressor;
The operation of injecting the reduced-pressure refrigerant into the intermediate pressure portion of the compressor is stopped, and after the refrigerating machine oil is injected into the intermediate pressure portion of the compressor, the operation of injecting the refrigerating machine oil is stopped, and the reduced-pressure refrigerant is supplied to the compressor The refrigeration apparatus is controlled to be injected into the intermediate pressure portion. A compressor, an oil separator for separating refrigeration oil contained in the high-pressure refrigerant compressed by the compressor, a condenser for condensing the high-pressure refrigerant separated by the oil separator, and condensation by the condenser In a refrigeration apparatus comprising a refrigeration cycle configured by sequentially connecting a decompression mechanism for decompressing the high-pressure refrigerant and an evaporator for evaporating the low-pressure refrigerant decompressed by the decompression mechanism,
An intermediate pressure injection circuit for extracting a portion of the high-pressure refrigerant circulating in the main circuit of the refrigeration cycle and injecting the reduced-pressure refrigerant reduced in pressure into the intermediate pressure portion of the compressor;
The decompressed refrigerant obtained by extracting and decompressing a part of the high-pressure refrigerant circulating in the main circuit of the refrigeration cycle is subjected to heat exchange with the high-pressure refrigerant circulating in the main circuit in a supercooling heat exchanger, and then the intermediate pressure of the compressor A liquid refrigerant cooling circuit to be injected into the unit,
An intermediate pressure oil return circuit for returning the refrigeration oil separated by the oil separator to the intermediate pressure portion of the compressor;
A suction section oil return circuit for returning the refrigeration oil separated by the oil separator to the suction section of the compressor;
The refrigeration apparatus, wherein the intermediate pressure injection circuit and the liquid refrigerant cooling circuit are connected to an intermediate pressure portion of a compressor through the same pipe as the intermediate pressure oil return circuit.

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