JP6076173B2 - Refrigeration equipment - Google Patents

Description

  The present invention relates to a refrigeration apparatus.

  Conventionally, in order to reduce supercharging to the compressor, there has been a refrigeration apparatus including a compressor in which a pump that changes the displacement volume between an inner rotor and an outer rotor is formed (see, for example, Patent Document 1). ).

JP 2005-42577 A (paragraph [0015])

  The compressor described in Patent Document 1 reduces the supercharging to the compressor by reducing the displacement volume in accordance with the increase in the rotational speed.

  However, in the compressor as described in Patent Document 1, the structure of the compressor has been changed in order to adjust the amount of oil with an oil pump inside the compressor. Therefore, the compressors provided in the refrigeration apparatus have been diversified.

  In other words, the compressor had to be produced according to the intended use. Therefore, there are problems that the manufacturing cost of the compressor increases and the compressor cannot be standardized.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a refrigeration apparatus that can reduce the manufacturing cost of a compressor and standardize the compressor.

The refrigeration apparatus according to the present invention is a refrigeration apparatus in which a compressor, an oil separator, a condenser, a throttling device, a cooler, and a gas-liquid separator are sequentially connected by a refrigerant pipe, and the compression of the refrigerant pipe A compressor suction pipe provided between the suction side of the compressor and the gas-liquid separator, the oil separator and the compressor suction pipe, and the oil stored in the oil separator An oil return pipe that supplies the compressor, an oil return solenoid valve that is provided in the oil return pipe and controls the amount of oil supplied, a heater attached to the cooler, the heater, and the compressor and a control unit for controlling the supply amount of oil, the control unit, after the defrosting operation of the cooler by heating the heater in a state of opening the oil return solenoid valve, wherein The suction pipe temperature that is the temperature of the compressor suction pipe and the suction pressure that is the pressure of the compressor suction pipe The suction superheat degree is obtained based on the corresponding suction pressure saturation temperature, and after the suction superheat degree becomes equal to or lower than a first threshold value set in advance, it is equal to or higher than a second threshold value set larger than the first threshold value. The oil return solenoid valve is closed when the oil return solenoid valve is closed, and the oil return solenoid valve is opened when a predetermined time threshold elapses after the oil return solenoid valve is closed .

  In the present invention, a circuit for adjusting the amount of oil inside the compressor is provided outside the compressor. Therefore, since the compressors are not diversified, it is possible to provide a refrigeration apparatus that can reduce the manufacturing cost of the compressors and standardize the compressors.

It is a figure which shows an example of schematic structure of the freezing apparatus 1 in Embodiment 1 of this invention. It is a figure which shows an example of the internal structure of the gas-liquid separator 56 in Embodiment 1 of this invention. It is a figure which shows an example of arrangement | positioning structure of the various sensors of the freezing apparatus 1 in Embodiment 1 of this invention. It is a figure which shows an example of a function structure of the outdoor control part 81 in Embodiment 1 of this invention. It is a figure which shows the suction | inhalation SH characteristic curve 301 in the case of resetting during the liquid back driving | operation in Embodiment 1 of this invention, and a liquid back driving | operation. It is a flowchart explaining the example of control of the freezing apparatus 1 in Embodiment 1 of this invention. It is a figure which shows an example of arrangement | positioning structure of the various sensors of the freezing apparatus 1 in Embodiment 2 of this invention. It is a figure which shows an example of a function structure of the outdoor control part 81 in Embodiment 2 of this invention. It is a flowchart explaining the example of control of the freezing apparatus 1 in Embodiment 2 of this invention. It is a figure which shows an example of arrangement | positioning structure of the various sensors of the freezing apparatus 1 in Embodiment 3 of this invention. It is a figure which shows an example of a function structure of the outdoor control part 81 in Embodiment 3 of this invention. It is a flowchart explaining the example of control of the freezing apparatus 1 in Embodiment 3 of this invention. It is a figure which shows an example of schematic structure of the freezing apparatus 1 in Embodiment 4 of this invention. It is a figure which shows an example of a function structure of the outdoor control part 81 in Embodiment 4 of this invention. It is a flowchart explaining the example of control of the freezing apparatus 1 in Embodiment 4 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, although the step which describes the program which performs operation | movement of Embodiment 1-4 of this invention is a process performed in time series along the order described, it does not necessarily process in time series, it is parallel Processing that is executed manually or individually may also be included.

  It does not matter whether each function described in the first to fourth embodiments is realized by hardware or software. That is, each block diagram described in the first to fourth embodiments may be considered as a hardware block diagram or a software functional block diagram. For example, each block diagram may be realized by hardware such as a circuit device, or may be realized by software executed on an arithmetic device such as a processor (not shown).

  In addition, each block in the block diagrams described in the first to fourth embodiments only needs to have its function implemented, and the configuration may not be separated by each block.

  Moreover, each refrigerant circuit demonstrated by this Embodiment 1-4 shows an example, and is not limited to the description matter shown in figure.

  In each of the first to fourth embodiments, items not particularly described are the same as those in the first to fourth embodiments, and the same functions and configurations are described using the same reference numerals.

  Moreover, this Embodiment 1-4 may be implemented independently and may be implemented in combination. In either case, the advantageous effects described below can be obtained.

  Moreover, the setting examples of various values and flags described in each of the first to fourth embodiments are merely examples, and are not particularly limited thereto.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating an example of a schematic configuration of a refrigeration apparatus 1 according to Embodiment 1 of the present invention. As shown in FIG. 1, the refrigeration apparatus 1 includes an outdoor unit 31 provided in the outdoor region 11 and an indoor unit 41 provided in the indoor region 21, and the outdoor unit 31 and the indoor unit 41 are configured of a refrigerant pipe. They are connected by an indoor / outdoor communication pipe 101 that forms a part.

  The outdoor region 11 is outdoors, for example, and the outdoor unit 31 is installed outdoors. The indoor region 21 is, for example, a freezing room that cools various products such as the object to be cooled 200, and the indoor unit 41 is installed in the freezing room.

  The outdoor unit 31 includes a compressor 51, an oil separator 52, a condenser 53, a gas-liquid separator 56, an oil return solenoid valve 61, an outdoor blower 71, an outdoor control unit 81, and the like. The indoor unit 41 includes an expansion device 54, a cooler 55, an indoor blower 72, an indoor control unit 83, and the like. In the refrigeration apparatus 1, a compressor 51, an oil separator 52, a condenser 53, a throttling device 54, a cooler 55, and a gas-liquid separator 56 are sequentially connected by a refrigerant pipe to form a refrigerant circuit. In other words, a refrigerant circuit is formed in the refrigeration apparatus 1, and the refrigerant is repeatedly circulated through the refrigerant circuit, whereby a refrigeration cycle is performed.

  The refrigeration apparatus 1 is used in, for example, a supermarket, a convenience store, or a refrigeration warehouse. As will be described later, the refrigeration apparatus 1 has a configuration in which the amount of oil supplied to the compressor 51 is excessive, thereby lowering the quality of the compressor 51 and preventing problems such as deterioration in performance or failure. I have. Schematically, in the refrigeration apparatus 1, when the liquid back operation to the compressor 51 is performed for a predetermined time and then the liquid back operation to the compressor 51 is canceled, the oil separator 52 to the compressor 51 The amount of oil returned to is adjusted. Next, details of the refrigeration apparatus 1 will be described.

  The compressor 51 compresses the refrigerant to high temperature and high pressure, and discharges the high-temperature and high-pressure refrigerant. The compressor 51 is driven by inverter control, for example. When discharging the refrigerant, the compressor 51 may discharge not only the refrigerant but also oil that lubricates a sliding portion (not shown) of the compressor 51. Therefore, the oil separator 52 is connected between the compressor 51 and the condenser 53 via a refrigerant pipe.

  The oil separator 52 includes a mechanism that separates the oil discharged from the compressor 51. The oil separator 52 has three ports. The oil separator 52 is connected to the discharge side of the compressor 51. The oil separator 52 is also connected to the suction side of the compressor 51. The oil separator 52 is connected to the inlet side of the condenser 53, that is, the upstream side. An oil return pipe 103 is provided between the oil separator 52 and the suction side of the compressor 51.

  Specifically, a compressor suction pipe 105 that forms a part of the refrigerant pipe is provided between the gas-liquid separator 56 and the suction side of the compressor 51, and the compressor suction pipe 105 and the oil separation pipe are separated from each other. An oil return pipe 103 is connected to the container 52. The oil return pipe 103 is provided with an oil return solenoid valve 61, and the oil return solenoid valve 61 adjusts the flow rate of the oil flowing through the oil return pipe 103 by adjusting the opening degree. Therefore, when the oil return solenoid valve 61 is open, the oil separated and stored in the oil separator 52 returns to the compressor 51 through the oil return pipe 103 and the compressor suction pipe 105. The oil level is secured.

  The condenser 53 performs heat exchange between the air supplied from the outdoor blower 71 and the refrigerant discharged from the compressor 51 supplied via the oil separator 52, condenses the refrigerant, and condenses the condensed refrigerant indoors. This is supplied to the expansion device 54 via the external communication pipe 101.

  The expansion device 54 reduces the pressure by reducing the supplied refrigerant. The throttling device 54 is, for example, an electronic expansion valve, but is not particularly limited thereto, and may be a capillary tube. The cooler 55 performs heat exchange between the air supplied from the indoor blower 72 and the decompressed refrigerant supplied from the expansion device 54, evaporates the refrigerant, and cools the surroundings. The gas-liquid separator 56 will be described later in detail with reference to FIG. 2, but includes a mechanism that does not allow the liquid refrigerant to flow to the compressor 51.

  Next, the operation of the refrigeration cycle will be described. The high-temperature and high-pressure gas refrigerant discharged from the compressor 51 passes through a refrigerant pipe connecting the compressor 51 and the oil separator 52, and the gas refrigerant is separated from the oil by the oil separator 52, and is supplied to the condenser 53. Led. The gas refrigerant guided to the condenser 53 undergoes heat exchange in the condenser 53 and liquefies. The liquefied refrigerant passes through the indoor / outdoor communication pipe 101 and is led from the outdoor unit 31 to the indoor unit 41. The liquefied refrigerant guided to the indoor unit 41 is squeezed by the expansion device 54 to become a gas-liquid two-phase refrigerant, which absorbs heat and exchanges heat with the cooler 55. The gasified refrigerant is guided from the indoor unit 41 to the outdoor unit 31 via the indoor / outdoor communication pipe 101, and the gas-liquid separator 56 separates the gaseous refrigerant and the liquid refrigerant, and compresses only the gaseous refrigerant. Machine 51 inhales. As described above, the refrigerant circulates in the refrigerant circuit, whereby the refrigeration cycle is performed. Next, the structure of the gas-liquid separator 56 will be described.

  FIG. 2 is a diagram illustrating an example of the internal configuration of the gas-liquid separator 56 according to Embodiment 1 of the present invention. As shown in FIG. 2, the gas-liquid separator 56 includes a container portion 56a as a housing. An internal space corresponding to a predetermined volume is formed inside the container portion 56a. When the gas-liquid two-phase refrigerant returns from the indoor unit 41 to the outdoor unit 31, the gas-liquid two-phase refrigerant that has returned to the internal space is temporarily stored, so that the liquid refrigerant is sucked into the compressor 51. The liquid back, which is a phenomenon that occurs, can be prevented.

  The container portion 56a is provided with an inlet pipe 56b and an outlet pipe 56c. The inlet pipe 56b is formed of, for example, a member having a longitudinal direction, and a part of the member is accommodated above the container portion 56a. The end of the inlet pipe 56 b that is exposed to the outside of the container portion 56 a is connected to the indoor / outdoor communication pipe 101.

  Outlet pipe 56c has a portion corresponding to a U-shaped portion housed in container portion 56a among the portions formed in a J-shape. The end of the outlet pipe 56 c that is exposed to the outside of the container portion 56 a is connected to the compressor 51. Of the outlet pipe 56c, the suction port 56d formed at the end part accommodated in the container part 56a is provided below the inlet pipe 56b accommodated in the container part 56a, so that only the gas refrigerant is compressed. Sucked into machine 51. The outlet pipe 56c is provided with an oil return hole 56e in the lower part of the portion corresponding to the U shape. The oil return hole 56e is used when the oil returns from the indoor unit 41 to the compressor 51 together with the gas refrigerant.

  Here, the reason why oil may return from the indoor unit 41 will be described. Most of the oil discharged from the compressor 51 is captured by the oil separator 52 and returned to the compressor 51 through the oil return pipe 103, but a part of the oil discharged from the compressor 51 is returned to the oil separator 52. The oil separator 52 passes through and flows out to the indoor unit 41. Therefore, the oil that has flowed into the indoor unit 41 returns to the outdoor unit 31 again through the cooler 55, returns to the gas-liquid separator 56, and is stored in the container portion 56a. The oil that has entered the container portion 56a has a specific gravity and is heavier than the gas refrigerant. Therefore, oil accumulates in the lower part of the container part 56a. Therefore, an oil return hole 56e is provided to return the accumulated oil to the compressor 51.

  By the way, as the object to be cooled 200, food or the like that needs to be stored at a low temperature is assumed. The outdoor unit 31 is called a refrigerator. In the field of refrigerators, the outdoor unit 31 and the indoor unit 41 are generally not installed as a set. That is, the outdoor unit 31 and the indoor unit 41 are manufactured by different manufacturers. Therefore, the refrigerator as the outdoor unit 31 is combined with various indoor units 41 from various manufacturers, so that the indoor environment of the indoor region 21 is optimized. That is, the indoor region 21 side and the outdoor region 11 side are often configured such that the indoor unit 41 individually operates and stops without exchanging various information through communication with each other.

  Moreover, the refrigerator which is the outdoor unit 31 is often installed in a large warehouse or a large supermarket. Therefore, the indoor unit 41 and the outdoor unit 31 may be installed in places separated from each other. For example, the indoor / outdoor communication pipe 101 that connects the indoor unit 41 and the outdoor unit 31 is often about 100 m.

  Therefore, the oil viscosity rises at low temperatures, such as the low-pressure indoor / outdoor communication pipe 101 and the low-pressure side cooler 55, so that the oil does not flow easily and the oil stays on the inner wall surface of the pipe. To do. Therefore, as the indoor / outdoor communication pipe 101 becomes longer or as the volume of the cooler 55 becomes larger, the amount of oil staying in the system of the refrigerant circuit increases due to the oil discharged from the compressor 51. Accordingly, it is necessary to secure a large amount of necessary oil in the entire refrigerant circuit system.

  Moreover, since the indoor unit 41 and the indoor / outdoor communication pipe 101 are different for each property, the refrigerator that is the outdoor unit 31 requires different amounts of oil for the entire system, which is a system that forms a refrigerant circuit. Therefore, depending on the local situation where the indoor unit 41 is installed, oil charging into the system forming the refrigerant circuit is often performed when the outdoor unit 31 is installed.

  Normally, guidance is given to determine the amount of additional oil in the site according to the volume of the indoor / outdoor communication pipe 101, so that a system that forms a local refrigerant circuit is used during piping work at the site. Add the appropriate oil. As a result, during normal operation, oil stays on the inner wall surface of the indoor / outdoor communication pipe 101 and the inner wall surface of the pipe provided in the cooler 55, so that the amount of oil inside the compressor 51 is maintained appropriately. It is.

  In addition, in order to store the object to be cooled 200 at a low temperature, the refrigeration apparatus 1 needs to set the refrigerant temperature to a low value. For example, in a refrigerated storage or the like, the refrigeration apparatus 1 is always operated at 0 ° C. or less with frost. On the premise that this is done, a cooling operation is performed for a predetermined time, and a defrosting operation, that is, a defrost operation is performed for a predetermined time. That is, the refrigeration apparatus 1 performs the cooling operation and the defrost operation alternately.

  As defrost operation, there are generally an off-cycle defrost method and a heater defrost method. The off-cycle defrost method is a method in which the operation of the compressor 51 is stopped and the indoor blower 72 is operated to apply indoor air to the cooler 55 to melt frost. The heater defrost method is a method in which a heater is attached to the cooler 55 and frost is melted by heating the heater.

  In the off-cycle defrost method, if the indoor temperature is set to a high value, the defrost can be performed only by the blowing operation using the indoor blower 72, so that power consumption can be suppressed and energy saving is achieved. However, in the off-cycle defrost method, if the room temperature is set to a low value, the frost adhering to the cooler 55 cannot be melted even if low temperature indoor air is applied to the cooler 55.

  Therefore, when the room temperature is set to a low value, the heater defrost method is adopted. In the heater defrost method, the indoor blower 72 is stopped and the heater attached to the cooler 55 is energized and heated to melt frost attached to the cooler 55. However, the heating operation using the heater also heats the cooler 55 main body that does not need to be heated. Therefore, when the defrost operation using the heater defrost method is finished and the cooling operation is started again, the cooler 55 is in a warmed state. Therefore, if heat is exchanged between the room air and the cooler 55 in this state, the room air is warmed, so that the environment in which the low temperature state is to be maintained is disturbed, and the temperature of the object to be cooled 200 may not be maintained. . In particular, in order to maintain the freshness of food and the like, blowing out warm air is not allowed.

  Therefore, in the heater defrost method, after the defrost operation is completed, the cooled cooler 55 is cooled, so that the operation of the indoor blower 72 is stopped and the cooler 55 is sufficiently cooled for the first few minutes after the start of the cool operation. Do. Thereafter, the fan of the indoor blower 72 is operated, and heat is exchanged with room air by the cooler 55 that is sufficiently cooled.

  That is, the operation of the fan of the indoor blower 72 is performed with a delay, and this operation is called a fan delay operation. During the fan delay operation, the refrigerant that should evaporate in the indoor unit 41 does not evaporate and returns to the outdoor unit 31. Therefore, in the sense of liquid back by fan delay operation, it is called fan delay liquid back operation. The fan delayed liquid back operation is a liquid back mode that always occurs in the refrigeration apparatus 1 employing the heater defrost method.

  The fan delay liquid back operation corresponds to the liquid back operation in the present invention.

  Therefore, if the fan delay liquid back operation is performed on the refrigeration apparatus 1 adopting the heater defrost system, the frost is melted and the cooled object 200 is kept at a low temperature without blowing the hot air to the cooled object 200. be able to.

  However, it is necessary to consider the behavior of oil in the refrigerant circuit during fan delay liquid back operation. As described above, some of the oil that has passed through the oil separator 52 and reached the indoor unit 41 remains in the cooler 55 and the indoor / outdoor communication pipe 101. If the fan delay liquid back operation is performed, the refrigerant in the two-phase state flows in the pipe inside the cooler 55 and inside the indoor / outdoor connecting pipe 101, and the oil is discharged together with the liquid refrigerant at a time by the so-called flushing phenomenon. Come back to 31. The oil and liquid refrigerant that have returned to the outdoor unit 31 are stored in the gas-liquid separator 56.

  However, when the indoor / outdoor communication pipe 101 is arranged in a long state and there are a large amount of refrigerant and oil in the system of the refrigerant circuit formed in the refrigeration apparatus 1, it is provided on the outlet side of the gas-liquid separator 56. Oil is sucked into the compressor 51 together with the liquid refrigerant from the suction port 56d of the outlet pipe 56c. That is, the oil retained in the indoor / outdoor communication pipe 101 and the cooler 55 enters the compressor 51. Therefore, in order to maintain an appropriate amount of oil in the entire system on the assumption that the oil does not flow into the compressor 51, the oil is also put into the indoor / outdoor communication pipe 101 and the cooler 55, but the oil does not flow into the compressor 51. Therefore, in the compressor 51, the oil becomes excessive.

  Next, the operation of the refrigeration apparatus 1 when the compressor 51 has excessive oil will be described. When the amount of oil in the compressor 51 becomes excessive, the amount of oil discharged from the compressor 51 increases, so the amount of oil separated by the oil separator 52 also increases. Therefore, the amount of oil return supplied from the oil separator 52 to the compressor suction pipe 105 via the oil return pipe 103 increases.

  Incidentally, the oil discharged from the compressor 51 is at a high temperature corresponding to the refrigerant temperature discharged from the compressor 51. Therefore, the temperature of the gas refrigerant sucked from the compressor 51 by returning a large amount of such high-temperature oil is equal to the temperature of the gas refrigerant sucked by the compressor 51 previously assumed in the outdoor unit 31. As compared with the above, it is sucked into the compressor 51 in a raised state.

  Therefore, if the temperature of the gas refrigerant sucked into the compressor 51 rises, the temperature of the refrigerant discharged from the compressor 51 rises compared to the assumed value, and the temperature of the oil stored in the compressor 51 also increases. To rise. As the refrigeration cycle operates, the temperature of the gas refrigerant sucked into the compressor 51, the temperature of the refrigerant discharged from the compressor 51, and the temperature of the oil stored in the compressor 51 are increased. Since the rise is repeated, the temperature of the oil rises abnormally inside the compressor 51.

  As a result, the lubricity of the oil decreases, and a sliding portion (not shown) inside the compressor 51 does not operate for lubrication, causing a failure of the compressor 51.

  However, during the fan delay liquid back operation, the liquid refrigerant is sucked together with the oil from the suction port 56d of the gas-liquid separator 56 and supplied to the compressor 51. Therefore, the refrigerant latent heat of the liquid refrigerant causes the oil inside the compressor 51 to An increase in temperature is avoided.

  Therefore, the rise in the temperature of the oil in the compressor 51 occurs when the compressor 51 stops sucking the liquid refrigerant, that is, when the fan delay liquid back operation is finished. Specifically, the fan delay liquid back operation is continuously performed for a predetermined time, and when the fan delay liquid back operation ends and the fan delay liquid back operation shifts to the normal operation, the fan delay liquid back operation is supplied to the compressor 51. Therefore, there is a risk that the compressor 51 will be in trouble due to an excessive amount of oil.

  Therefore, in the first embodiment, the oil return amount to the compressor 51 is adjusted after returning from the fan delay liquid back operation to the normal operation. Specifically, when the fan delay liquid back operation is performed at a predetermined time and returned to the normal operation, the oil return solenoid valve 61 is closed at the predetermined time, and the oil separator 52 is stored. Overflowing the oil that is present, the oil flows out to the indoor unit 41 side.

  As a result, the oil is retained in the indoor / outdoor communication pipe 101 and the cooler 55 and the oil is retained in the compressor 51 in an appropriate amount as before the fan delay liquid back operation. Therefore, since the compressor 51 has an appropriate amount of oil, the performance maintenance and reliability of the compressor 51 can be ensured. That is, in the fan delay liquid back operation, the adjustment control of the oil supply amount to the compressor 51 is stopped, and in the normal operation, the adjustment control of the oil supply amount to the compressor 51 is executed.

  Next, an example of realizing by sensing using various sensors whether the fan delay liquid back operation is being executed or whether the fan delay liquid back operation has returned to the normal operation will be described.

  FIG. 3 is a diagram illustrating an example of an arrangement configuration of various sensors of the refrigeration apparatus 1 according to Embodiment 1 of the present invention. The compressor suction pipe 105 is provided with a low pressure sensor 91 and a suction pipe temperature sensor 92. The low pressure sensor 91 detects the suction pressure of the compressor 51. The suction pipe temperature sensor 92 detects the temperature of the compressor suction pipe 105, that is, the suction pipe temperature.

  If the fan delay liquid back operation is not being executed, the suction superheat degree, that is, the suction SH is in a state where it is secured at a second temperature threshold value that is a predetermined value or more, for example, about 5K or more. The suction SH is obtained from the difference between the suction gas temperature TS, which is the suction pipe temperature, and the suction pressure saturation temperature TE corresponding to the suction pressure.

  If the fan delay liquid back operation is being executed, the suction SH is reduced to a predetermined value or less, for example, about 0K or less.

  Therefore, when the fan delay liquid back operation returns to the normal operation, the suction SH returns to the state secured at the second temperature threshold value that is a predetermined value or more, for example, about 5K or more. That is, if the value of the suction SH is obtained, it can be determined whether the fan delay liquid back operation is being performed or whether the normal operation has been restored from the fan delay liquid back operation.

  As described above, when the fan retarded liquid back operation returns to the normal operation, there is a possibility that the amount of oil supplied to the compressor 51 becomes excessive. Then, the control which maintains the oil quantity inside the compressor 51 appropriately by adjusting the oil return electromagnetic valve 61 appropriately is demonstrated concretely using FIGS.

  FIG. 4 is a diagram illustrating an example of a functional configuration of the outdoor control unit 81 according to Embodiment 1 of the present invention. As shown in FIG. 4, the outdoor control unit 81 includes a suction SH calculation unit 201, a liquid back operation determination unit 205, a timer unit 206, and an oil return electromagnetic valve open / close determination unit 207. The suction SH calculation unit 201 obtains the suction SH based on the suction pressure and the suction pipe temperature. When calculating the suction pressure saturation temperature TE corresponding to the suction pressure, the suction SH calculation unit 201 stores, for example, a thermodynamic property table defined for each refrigerant in advance as data and obtains it by referring to it. Alternatively, it may be obtained by a predefined arithmetic expression.

  The liquid back operation determination unit 205 determines whether or not the fan delay liquid back operation is being performed based on the suction SH. For example, the liquid back operation determination unit 205 determines that the fan delay liquid back operation is being performed when the suction SH is equal to or lower than a first temperature threshold that is a predetermined temperature threshold. The liquid back operation determination unit 205 determines that the state where the suction SH is equal to or lower than the first temperature threshold has shifted from the normal operation to the fan delay liquid back operation, and a first time threshold which is a predetermined time threshold, for example, After 3 minutes, which is often the fan delay time, has elapsed, the determination process is transferred to the oil return solenoid valve open / close determination unit 207.

  The liquid back operation determination unit 205 determines whether or not the first time threshold has elapsed based on the time measurement result acquired from the time measurement unit 206.

  Since the liquid back operation determination unit 205 uses the newly obtained suction SH for each determination, the liquid branch operation determination unit 205 sets a processing branch flag in advance, and sets the processing branch flag when the suction SH becomes the first temperature threshold. By changing, it may be determined that the suction SH is a value different from the previous value.

  The oil return solenoid valve open / close determination unit 207 determines that the fan delay liquid back operation has ended and the normal operation has been restored from the fan delay liquid back operation when the suction SH is equal to or higher than a second temperature threshold that is a predetermined temperature threshold. to decide.

  Specifically, the oil return solenoid valve opening / closing determination unit 207 determines that the fan delayed liquid back operation has returned to the normal operation when the suction SH is equal to or higher than the second temperature threshold, and closes the oil return electromagnetic valve 612. After a second time threshold which is a predetermined time threshold, for example, 5 minutes has elapsed, it is determined that normal operation is being performed, and a control command to open the oil return solenoid valve 61 is issued.

  The oil return solenoid valve open / close determination unit 207 determines whether or not the second time threshold has elapsed based on the time measurement result acquired from the time measurement unit 206.

  The second temperature threshold corresponds to the temperature threshold in the present invention, and the second time threshold corresponds to the time threshold in the present invention.

  FIG. 5 is a diagram showing an intake SH characteristic curve 301 during and after returning from the liquid back operation according to Embodiment 1 of the present invention. As shown in FIG. 5, when the intake SH characteristic curve 301 is equal to or lower than the first temperature threshold, the fan delay liquid back operation is being performed. Further, when the suction SH characteristic curve 301 is equal to or higher than the second temperature threshold, the state is returned from the fan delay liquid back operation to the normal operation.

  FIG. 6 is a flowchart for explaining a control example of the refrigeration apparatus 1 according to Embodiment 1 of the present invention.

(Step S11)
The outdoor control unit 81 sets the processing branch flag to 1.

(Step S12)
The outdoor control unit 81 acquires the suction pipe temperature.

(Step S13)
The outdoor control unit 81 sets the suction pipe temperature to the suction gas temperature TS.

(Step S14)
The outdoor control unit 81 acquires the suction pressure.

(Step S15)
The outdoor control unit 81 obtains the suction pressure saturation temperature TE from the suction pressure.

(Step S16)
The outdoor control unit 81 obtains the intake SH based on the intake gas temperature TS and the intake pressure saturation temperature TE.

(Step S17)
The outdoor control unit 81 determines whether or not the processing branch flag is 1. If the processing branch flag is 1, the outdoor control unit 81 proceeds to step S18. On the other hand, if the processing branch flag is not 1, the outdoor control unit 81 proceeds to step S24.

(Step S18)
The outdoor control unit 81 acquires a predetermined first temperature threshold value.

(Step S19)
The outdoor control unit 81 determines whether or not the suction SH is equal to or lower than the first temperature threshold value. The outdoor control unit 81 proceeds to step S20 when the suction SH is equal to or lower than the first temperature threshold. On the other hand, the outdoor control unit 81 returns to step S12 when the suction SH is not less than or equal to the first temperature threshold.

(Step S20)
The outdoor control unit 81 sets the processing branch flag to 0.

(Step S21)
The outdoor control unit 81 acquires a predetermined first time threshold value.

(Step S22)
The outdoor control unit 81 starts measuring time.

(Step S23)
The outdoor control unit 81 determines whether or not the measured time has passed the first time threshold. The outdoor control part 81 returns to step S12, when the time measured has passed the 1st time threshold value. On the other hand, the outdoor control part 81 returns to step S23, when the time measured has not passed the 1st time threshold value.

(Step S24)
The outdoor control unit 81 acquires a predetermined second temperature threshold value.

(Step S25)
The outdoor control unit 81 determines whether or not the suction SH is equal to or higher than the second temperature threshold. If the intake SH is equal to or higher than the second temperature threshold, the outdoor control unit 81 proceeds to step S26. On the other hand, the outdoor control unit 81 returns to step S12 when the suction SH is not equal to or higher than the second temperature threshold.

(Step S26)
The outdoor control unit 81 issues a control command for closing the oil return solenoid valve 61.

(Step S27)
The outdoor control unit 81 acquires a predetermined second time threshold value.

(Step S28)
The outdoor control unit 81 starts measuring time.

(Step S29)
The outdoor control unit 81 determines whether the measured time has passed the second time threshold. The outdoor control unit 81 proceeds to step S30 when the measured time has passed the second time threshold. On the other hand, the outdoor control part 81 returns to step S29, when the time measured does not pass the 2nd time threshold value.

(Step S30)
The outdoor control unit 81 issues a control command to open the oil return solenoid valve 61 and ends the process.

  From the above description, the refrigeration apparatus 1 is provided with a circuit that adjusts the amount of oil inside the compressor 51 outside the compressor 51. Therefore, since the compressor 51 is not diversified, the manufacturing cost of the compressor 51 can be reduced and the compressor 51 can be standardized.

  As described above, in the first embodiment, the compressor 51, the oil separator 52, the condenser 53, the expansion device 54, the cooler 55, and the gas-liquid separator 56 are sequentially connected by the refrigerant pipe. The outdoor control unit 81 controls the amount of oil supplied to the compressor 51. The outdoor control unit 81 is in a gas phase state between the outlet of the cooler 55 and the inlet of the gas-liquid separator 56. When the normal operation, which is the operation state in which the refrigerant is circulated, and the liquid back operation, which is the operation state in which the refrigerant in the two-phase state or the liquid phase state is circulated, the oil separation is performed when the normal operation is shifted to the liquid back operation. When the control for adjusting the amount of oil supplied from the compressor 52 to the compressor 51 is stopped and the normal operation is returned from the liquid back operation, the control for adjusting the amount of oil supplied from the oil separator 52 to the compressor 51 is executed. A refrigeration apparatus 1 is configured.

  Since the compressor 51 is not diversified due to the above configuration, the manufacturing cost of the compressor 51 can be reduced and the compressor 51 can be standardized.

  In the first embodiment, among the refrigerant pipes, the compressor suction pipe 105, the oil separator 52, and the compressor provided between the suction side of the compressor 51 and the gas-liquid separator 56 are provided. An oil return pipe 103 provided between the suction pipe 105 and supplying oil stored in the oil separator 52 to the compressor 51, and an oil return solenoid valve 61 provided in the oil return pipe 103 and controlling the amount of oil supplied. When the outdoor control unit 81 returns from the liquid back operation to the normal operation, the outdoor control unit 81 determines that the liquid back operation has returned to the normal operation, and closes the oil return electromagnetic valve 61.

  In the first embodiment, the outdoor control unit 81 includes a suction pipe temperature that is a temperature of the compressor suction pipe 105, a suction pressure saturation temperature corresponding to a suction pressure that is a pressure of the compressor suction pipe 105, and If the suction superheat degree is equal to or higher than a predetermined second temperature threshold and less than a predetermined second time threshold, it is determined that the liquid back operation has returned to the normal operation, When the oil return solenoid valve 61 is closed and the suction superheat is equal to or higher than the second temperature threshold value and higher than the second time threshold value, it is determined that the normal operation is being performed, and the oil return electromagnetic valve 61 is opened.

  Therefore, since the compressor 51 is not diversified, the manufacturing cost of the compressor 51 can be particularly significantly reduced, and the compressor 51 can be standardized.

Embodiment 2. FIG.
The difference from the first embodiment is that the determination of the fan delay liquid back operation is performed using the discharge SH. FIG. 7 is a diagram illustrating an example of an arrangement configuration of various sensors of the refrigeration apparatus 1 according to Embodiment 2 of the present invention. As shown in FIG. 7, a compressor discharge pipe 106 that is a refrigerant pipe is provided between the discharge side of the compressor 51 and the suction side of the oil separator 52. The compressor discharge pipe 106 is provided with a high pressure sensor 93 and a discharge pipe temperature sensor 94. The high pressure sensor 93 detects the discharge pressure of the compressor 51.

  FIG. 8 is a diagram illustrating an example of a functional configuration of the outdoor control unit 81 according to Embodiment 2 of the present invention. The outdoor control unit 81 includes a discharge SH calculation unit 202 that calculates discharge superheat, that is, discharge SH. The discharge SH calculation unit 202 calculates the discharge SH based on the discharge pipe temperature and the discharge pressure.

  Specifically, the discharge SH calculating unit 202 obtains the discharge SH by obtaining a difference between the discharge gas temperature TS that is the discharge pipe temperature and the discharge pressure saturation temperature TE corresponding to the discharge pressure. Similarly to the suction SH, the discharge SH also decreases rapidly during the fan delay liquid back operation, ends the fan delay liquid back operation, and increases rapidly after returning from the fan delay liquid back operation to the normal operation. Therefore, the outdoor control unit 81 can determine whether or not the fan delay liquid back operation is being performed using the discharge SH by executing the same control as the suction SH.

  FIG. 9 is a flowchart illustrating a control example of the refrigeration apparatus 1 according to Embodiment 2 of the present invention. Of the steps shown in FIG. 9, the processes of steps S42 to S46, the process of step S49, and the process of step S55 are processes related to the discharge SH, and otherwise the same processes are executed.

  As described above, in the second embodiment, among the refrigerant pipes, the compressor discharge pipe 106 provided on the discharge side of the compressor 51 is provided, and the outdoor control unit 81 has a discharge pipe temperature that is the temperature of the compressor discharge pipe 106. And a discharge pressure saturation temperature corresponding to a discharge pressure that is a pressure of the compressor discharge pipe 106, a discharge superheat degree is obtained, and the discharge superheat degree is equal to or higher than a predetermined second temperature threshold and is set in advance. If it is less than the second time threshold, it is determined that the liquid back operation has returned to the normal operation, it is determined that the liquid back operation has returned to the normal operation, the oil return solenoid valve 61 is closed, and the discharge superheat degree is the second. If the temperature is equal to or higher than the temperature threshold and equal to or higher than the second time threshold, it is determined that the normal operation is being performed, and the oil return solenoid valve 61 is opened.

  Due to the above configuration, the refrigeration apparatus 1 can determine whether or not the fan delay liquid back operation is being performed using the discharge SH. Therefore, a circuit for adjusting the oil amount inside the compressor 51 is provided outside the compressor 51. Since the compressor 51 is not diversified, the manufacturing cost of the compressor 51 can be reduced and the compressor 51 can be standardized.

Embodiment 3 FIG.
The difference from the first embodiment and the second embodiment is that the determination of the fan delay liquid back operation is executed using the under-shell SH. FIG. 10 is a diagram illustrating an example of an arrangement configuration of various sensors of the refrigeration apparatus 1 according to Embodiment 3 of the present invention. As shown in FIG. 10, the compressor suction pipe 105 is provided with a low pressure sensor 91. An under-shell temperature sensor 95 is provided below the shell that forms the outline of the compressor 51. The under-shell temperature sensor 95 detects the under-shell temperature. The low pressure sensor 91 detects a low pressure on the suction side of the compressor 51.

  FIG. 11 is a diagram illustrating an example of a functional configuration of the outdoor control unit 81 according to Embodiment 3 of the present invention. The outdoor control unit 81 includes an under-shell SH calculation unit 203 that calculates the under-shell superheat, that is, under-shell SH. The under-shell SH calculation unit 203 obtains the under-shell SH based on the under-shell temperature and the low pressure saturation temperature corresponding to the low pressure.

  Specifically, the under-shell SH computing unit 203 obtains the under-shell SH by obtaining the difference between the under-shell gas temperature TS, which is the under-shell temperature, and the low-pressure saturation temperature TE corresponding to the low-pressure pressure. Similarly to the suction SH and the discharge SH, the under-shell SH also decreases rapidly during the fan delay liquid back operation, ends the fan delay liquid back operation, and rapidly increases after returning from the fan delay liquid back operation to the normal operation. I will do it. Therefore, the outdoor control unit 81 can determine whether or not the fan delay liquid back operation is being performed using the under-shell SH by executing the same control as the suction SH.

  FIG. 12 is a flowchart illustrating a control example of the refrigeration apparatus 1 according to Embodiment 3 of the present invention. Of the steps shown in FIG. 12, the processes of steps S72 to S76, the process of step S79, and the process of step S85 are processes related to the shell under SH, and otherwise the same processes are executed. .

  As described above, the third embodiment includes the compressor suction pipe 105 provided between the suction side of the compressor 51 and the gas-liquid separator 56 in the refrigerant pipe, and the outdoor control unit 81 includes the compressor The under-shell superheat degree is obtained based on the under-shell temperature that is the temperature below the outer shell 51 and the low-pressure saturation temperature corresponding to the low-pressure pressure that is the pressure of the compressor suction pipe 105. When the temperature is equal to or higher than the predetermined second temperature threshold and lower than the predetermined second time threshold, it is determined that the liquid back operation has returned to the normal operation, the oil return solenoid valve 61 is closed, and the superheat degree below the shell is the first. When the temperature is equal to or higher than the two temperature threshold and equal to or higher than the second time threshold, it is determined that the normal operation is being performed, and the oil return solenoid valve 61 is opened.

  Due to the above configuration, the refrigeration apparatus 1 can determine whether or not the fan delay liquid back operation is being performed using the under-shell SH. Therefore, a circuit for adjusting the oil amount inside the compressor 51 is provided outside the compressor 51. Since the compressor 51 is not diversified, the manufacturing cost of the compressor 51 can be reduced and the compressor 51 can be standardized.

Embodiment 4 FIG.
The difference from the first to third embodiments is that a bypass circuit 107 and an oil separator circuit 108 are provided. FIG. 13 is a diagram showing an example of a schematic configuration of the refrigeration apparatus 1 according to Embodiment 4 of the present invention. As shown in FIG. 13, an oil separator circuit 108 that is a part of the refrigerant pipe is provided between the compressor discharge pipe 106 and the inlet side of the oil separator 52. Further, as shown in FIG. 13, a bypass circuit 107 is provided between the compressor discharge pipe 106 and the connection side to the condenser 53 among the outlet side of the oil separator 52.

  The oil separator circuit 108 is a supply path that supplies oil contained in the refrigerant discharged from the compressor 51 to the oil separator 52. The oil separator circuit 108 is provided with an oil separator circuit closing valve 63. The oil separator circuit stop valve 63 opens and closes the flow of the refrigerant to the oil separator 52.

  The bypass circuit 107 is a bypass circuit that supplies the refrigerant including the oil discharged from the compressor 51 to the condenser 53 by bypassing the oil separator 52. The bypass circuit 107 is provided with a bypass circuit electromagnetic valve 62. The bypass circuit solenoid valve 62 opens and closes the bypass circuit 107.

  FIG. 14 is a diagram illustrating an example of a functional configuration of the outdoor control unit 81 according to Embodiment 4 of the present invention. As illustrated in FIG. 14, the outdoor control unit 81 includes a solenoid valve open / close determination unit 209. The electromagnetic valve open / close determination unit 209 issues a control command for opening the bypass circuit electromagnetic valve 62 and a control command for closing the oil separator circuit closing valve 63 after returning from the fan delay liquid back operation to the normal operation.

  When the bypass circuit electromagnetic valve 62 is opened and the oil separator circuit closing valve 63 is closed, the electromagnetic valve open / close determining unit 209 may issue a control command for closing the oil return electromagnetic valve 61.

  The outdoor control unit 81 issues a control command to open the bypass circuit solenoid valve 62 after returning from the fan delay liquid back operation to the normal operation, and issues a control command to close the oil separator circuit shut-off valve 63, After the time threshold has elapsed, it is determined that normal operation is being performed, a control command for closing the bypass circuit electromagnetic valve 62 is issued, a control command for opening the oil separator circuit closing valve 63 is issued, and the oil return solenoid valve 61 is issued. It is only necessary to issue a control command to open.

  As a result, since the oil separator 52 is not supplied with the refrigerant containing oil from the compressor 51, the separation operation between the oil and the refrigerant stops. Further, the refrigerant discharged from the compressor 51 is supplied to the indoor unit 41 via the bypass circuit 107, the condenser 53, the indoor / outdoor communication pipe 101, and the compressor 51 from the oil return pipe 103. The oil return operation is temporarily stopped. Therefore, the oil is caused to flow out to the indoor unit 41 side, and the oil is retained on the inner wall surfaces of the indoor / outdoor communication pipe 101 and the cooler 55 as in the state before the fan delay liquid back operation. As a result, since the amount of oil becomes appropriate inside the compressor 51, the performance of the compressor 51 can be maintained and the reliability can be ensured.

  FIG. 15 is a flowchart for explaining a control example of the refrigeration apparatus 1 according to Embodiment 4 of the present invention. The process from step S116 to the process of step S124 is an operation accompanied when the bypass circuit 107 and the oil separator circuit 108 are provided.

  The solenoid valve open / close determining unit 209 may issue a control command for opening the bypass circuit solenoid valve 62 and a control command for opening the oil separator circuit closing valve 63 after returning from the fan delay liquid back operation to the normal operation. . Even in this operation, the oil can be allowed to flow out to the indoor unit 41, so that the amount of oil inside the compressor 51 can be prevented from falling into an excessive state. However, since the amount of oil flowing out to the indoor unit 41 is reduced as compared with the case where the oil separator circuit closing valve 63 is closed, the state where the bypass circuit electromagnetic valve 62 is opened is the case where the oil separator circuit closing valve 63 is closed. It may be set longer than that.

  As described above, in the fourth embodiment, the oil flowing in the oil separator circuit 108 that is provided in the pipe connecting the discharge side of the compressor 51 and the inlet side of the oil separator 52 and that is an oil supply path. An oil separator circuit shut-off valve 63 for stopping the supply of oil, a pipe connecting the discharge side of the compressor 51 and the outlet side of the oil separator 52, and a bypass circuit 107 serving as an oil detour is provided. A bypass circuit electromagnetic valve 62 for stopping the supply of flowing oil. When the outdoor control unit 81 determines that the liquid back operation has returned to the normal operation, the outdoor control unit 81 opens the bypass circuit electromagnetic valve 62, and the oil separator circuit When the closing valve 63 is closed and it is determined that normal operation is being performed, the bypass circuit electromagnetic valve 62 is closed and the oil separator circuit closing valve 63 is opened.

  Because of the above-described configuration, the amount of oil is appropriate in the compressor 51, so that the performance of the compressor 51 can be maintained and reliability can be ensured.

  In the first to fourth embodiments, the compressor 51 has been described as a single unit. However, the present invention is not particularly limited thereto. For example, even with a multi-type unit in which a plurality of compressors 51 are mounted, the same effect as described above can be obtained. In particular, in the multi-type unit, there is a difference in the oil discharge amount according to the individual difference of each compressor 51.

  Specifically, since there are variations in the oil return mechanism of each compressor 51, there are many factors that cause fluctuations in the oil amount inside the compressor 51. Further, in the fan delay liquid back operation, there is a high possibility that the amount of oil in each compressor 51 becomes excessive. Even in the case of such a multi-type unit, after returning from the fan delay liquid back operation to the normal operation, if any of the suction SH, discharge SH, and under-shell SH is equal to or higher than the second temperature threshold, the oil return electromagnetic By closing the valve 61 and opening the oil return solenoid valve 61 after the second time threshold has elapsed, it is possible to avoid an excessive amount of oil inside the compressor 51.

  The fan delay liquid back operation is a mode that always occurs in the heater defrost type defrosting control, and not only performs the above-described operation after returning from such fan delay liquid back operation, but also the throttle device. Even in the excessive oil state of the compressor 51 that occurs when a malfunction occurs in the control of 54, the oil amount in the entire system temporarily becomes inappropriate, the fan delay liquid back operation is performed, and then returns. The same effect can be obtained by executing the operation.

  DESCRIPTION OF SYMBOLS 1 Refrigerating device, 11 Outdoor area | region, 21 Indoor area | region, 31 Outdoor unit, 41 Indoor unit, 51 Compressor, 52 Oil separator, 53 Condenser, 54 Throttle device, 55 Cooler, 56 Gas-liquid separator, 56a Container part , 56b Inlet piping, 56c Outlet piping, 56d Suction port, 56e Oil return hole, 61 Oil return solenoid valve, 62 Bypass circuit solenoid valve, 63 Oil separator circuit shut-off valve, 71 Outdoor blower, 72 Indoor blower, 81 Outdoor controller , 83 Indoor control unit, 91 Low pressure sensor, 92 Suction pipe temperature sensor, 93 High pressure sensor, 94 Discharge pipe temperature sensor, 95 Under shell temperature sensor, 101 Indoor / outdoor communication pipe, 103 Oil return pipe, 105 Compressor suction pipe, 106 Compression Machine discharge pipe, 107 bypass circuit, 108 oil separator circuit, 200 object to be cooled, 201 suction SH calculation unit, 202 Discharge SH calculation unit, 203 shell under SH calculation unit, 205 liquid back operation determination unit, 206 timing unit, 207 oil return solenoid valve open / close determination unit, 209 solenoid valve open / close determination unit, 301 suction SH characteristic curve.

Claims (4)

A refrigerating apparatus in which a compressor, an oil separator, a condenser, a throttling device, a cooler, and a gas-liquid separator are sequentially connected by a refrigerant pipe,
Among the refrigerant pipes, a compressor suction pipe provided between the suction side of the compressor and the gas-liquid separator;
An oil return pipe connected to the oil separator and the compressor suction pipe and supplying the oil stored in the oil separator to the compressor;
An oil return solenoid valve that is provided in the oil return pipe and controls a supply amount of the oil;
A heater attached to the cooler;
And a control unit for controlling the supply amount of oil supplied to the heater, and the compressor,
The controller is
The heater is heated with the oil return solenoid valve opened to perform the defrosting operation of the cooler, and then the suction pipe temperature, which is the temperature of the compressor suction pipe, and the pressure of the compressor suction pipe are used. The suction superheat degree is calculated based on the suction pressure saturation temperature corresponding to a certain suction pressure,
When the suction superheat degree becomes equal to or lower than a first threshold value set in advance and then becomes equal to or higher than a second threshold value set higher than the first threshold value, the oil return solenoid valve is closed,
The refrigeration apparatus , wherein the oil return solenoid valve is opened when a predetermined time threshold elapses after the oil return solenoid valve is closed . A refrigerating apparatus in which a compressor, an oil separator, a condenser, a throttling device, a cooler, and a gas-liquid separator are sequentially connected by a refrigerant pipe,
Among the refrigerant pipes, a compressor suction pipe provided between the suction side of the compressor and the gas-liquid separator;
Among the refrigerant pipes, a compressor discharge pipe provided on the discharge side of the compressor;
An oil return pipe connected to the oil separator and the compressor suction pipe and supplying the oil stored in the oil separator to the compressor;
An oil return solenoid valve that is provided in the oil return pipe and controls a supply amount of the oil;
A heater attached to the cooler;
And a control unit for controlling the supply amount of oil supplied to the heater, and the compressor,
The controller is
After heating the heater with the oil return solenoid valve opened and performing the defrosting operation of the cooler, the discharge pipe temperature which is the temperature of the compressor discharge pipe and the pressure of the compressor discharge pipe The discharge superheat degree is calculated based on the discharge pressure saturation temperature corresponding to a certain discharge pressure,
When the discharge superheat degree becomes equal to or lower than a first threshold value set in advance and then becomes equal to or higher than a second threshold value set larger than the first threshold value, the oil return solenoid valve is closed,
The refrigeration apparatus , wherein the oil return solenoid valve is opened when a predetermined time threshold elapses after the oil return solenoid valve is closed . A refrigerating apparatus in which a compressor, an oil separator, a condenser, a throttling device, a cooler, and a gas-liquid separator are sequentially connected by a refrigerant pipe,
Among the refrigerant pipes, a compressor suction pipe provided between the suction side of the compressor and the gas-liquid separator;
An oil return pipe connected to the oil separator and the compressor suction pipe and supplying the oil stored in the oil separator to the compressor;
An oil return solenoid valve that is provided in the oil return pipe and controls a supply amount of the oil;
A heater attached to the cooler;
And a control unit for controlling the supply amount of oil supplied to the heater, and the compressor,
The controller is
After the heater is heated with the oil return solenoid valve opened to perform the defrosting operation of the cooler, the temperature below the shell, which is the temperature below the outer shell of the compressor, and the suction pipe of the compressor Based on the low pressure saturation temperature corresponding to the low pressure that is the pressure, the superheat degree under the shell is obtained,
After the degree of superheat under the shell is equal to or lower than a first threshold value set in advance, the oil return solenoid valve is closed when the value becomes equal to or higher than a second threshold value set larger than the first threshold value,
The refrigeration apparatus , wherein the oil return solenoid valve is opened when a predetermined time threshold elapses after the oil return solenoid valve is closed . An oil separator circuit that is provided in a pipe that connects between the discharge side of the compressor and the inlet side of the oil separator, and stops the supply of the oil flowing through the oil separator circuit that is the oil supply path A shut-off valve;
A bypass circuit solenoid valve for stopping supply of the oil flowing in the bypass circuit, which is provided in a pipe connecting the discharge side of the compressor and the outlet side of the oil separator;
With
The controller is
The oil return when closing the solenoid valve, closing the oil separator circuit closing valve further the bypass circuit electromagnetic valve with Open,
When the time threshold after closing the oil return solenoid valve has elapsed, further claim 1-3, characterized in that opening the bypass circuit closes the solenoid valve Rutotomoni the oil separator circuit shut-off valve The refrigeration apparatus according to one item.

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