JP2016211774A - Freezer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a freezer capable of eliminating two-layer separation in an accumulator through control.SOLUTION: An air conditioner 10 comprises: a compressor 20, an accumulator 70 and an outdoor control part 91. The compressor 20 is variable in rotating speed. The compressor 20 compresses a refrigerant changing in a state between a gas and a liquid. The accumulator 70 is provided on a suction side of the compressor 20. The accumulator 70 reserves an excessive refrigerant. The outdoor control part 91 controls driving of the compressor 20. The outdoor control part 91 includes a detection part 91a. The detection part 91a detects whether two-layer separation is caused in the accumulator 70. When the detection part 91a detects two-layer separation being caused, the outdoor control part 91 performs two-layer separation eliminating operation in which the compressor 20 is driven at a higher rotating speed than in oil return operation.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a refrigeration apparatus including an accumulator.

  Conventionally, there is a refrigeration apparatus including an accumulator having a function of temporarily storing refrigerant returned to the compressor and suppressing suction of liquid refrigerant into the compressor.

  Here, in the compressor, there may occur an oil rising phenomenon in which a part of the refrigeration oil stored in the compressor is discharged together with the gas refrigerant and flows out to the system. When an oil rising phenomenon occurs in a refrigeration apparatus including an accumulator, the discharged refrigeration oil may accumulate in the accumulator together with the liquid refrigerant before circulating through the refrigeration circuit and returning to the compressor. At this time, if the liquid refrigerant and the refrigerating machine oil are separated into two layers in the accumulator, the refrigerating machine oil accumulated in the accumulator becomes difficult to return to the compressor. If it does so, the problem that the compressor oil in a compressor will run short and a compressor will raise | generate a lubrication defect and will break down will arise.

  As a measure for solving this problem, for example, in the refrigeration apparatus disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2013-245836), the two-layer separation between the liquid refrigerant and the refrigerator oil in the accumulator is eliminated. Further, the suction pipe is extended to the bottom of the accumulator so that the opening of the suction pipe for sucking the refrigerant into the accumulator is located below the liquid level of the fluid stored in the accumulator. In this refrigeration apparatus, since the opening of the suction pipe is positioned at the bottom of the accumulator, when the refrigerant is sucked into the accumulator from the suction pipe, the liquid refrigerant and the refrigerating machine oil stored in the accumulator by the sucked refrigerant As a result, the two-layer separation between the liquid refrigerant and the refrigerating machine oil is eliminated.

  However, in the accumulator configured as in Patent Document 1, since the gas-rich refrigerant is poured into the fluid stored in the accumulator, foaming occurs in the liquid surface in the accumulator due to the poured refrigerant. There is a risk of rising. As a result, the accumulator must be designed with a volume that allows the rise in the liquid level, and the size of the accumulator increases.

  Then, the subject of this invention is providing the freezing apparatus which can eliminate the two-layer separation in an accumulator by control.

  A refrigeration apparatus according to a first aspect of the present invention includes a compressor, an accumulator, and a control unit. The rotation speed of the compressor is variable. The compressor compresses the refrigerant whose state changes between gas and liquid. The accumulator is provided on the suction side of the compressor. The accumulator stores excess refrigerant. The control unit controls driving of the compressor. The control unit includes a detection unit. The detection unit detects whether or not two layers are separated in the accumulator. When the detection unit detects that the two layers are separated, the control unit executes a two-layer separation elimination operation in which the compressor is driven at a higher rotational speed than the oil return operation.

  In the refrigeration apparatus according to the first aspect of the present invention, the two-layer separation elimination operation is executed when the two-layer separation is detected. For this reason, the shortage of refrigeration oil in the compressor due to the two-layer separation in the accumulator can be solved. In addition, here, the two-layer separation in the accumulator can be eliminated by the control of executing the two-layer separation elimination operation.

  Here, the two-layer separation means that the liquid refrigerant and the refrigerator oil rich phase are separated in the accumulator regardless of whether the liquid refrigerant and the refrigerator oil are compatible or not. I mean.

  In the refrigeration apparatus according to the second aspect of the present invention, in the refrigeration apparatus according to the first aspect, when the control unit satisfies a predetermined condition and it is not detected that the two-layer separation is detected by the detection unit. The oil return operation is executed. In this refrigeration apparatus, an oil return operation is performed separately from the two-layer separation elimination operation.

  In the refrigeration apparatus according to the third aspect of the present invention, in the refrigeration apparatus according to the second aspect, the control unit executes the two-layer separation elimination operation when the predetermined condition is satisfied. The predetermined condition includes a condition that the integrated value of the refrigerating machine oil flow amount, which is the refrigerating machine oil amount flowing out from the compressor, is equal to or greater than a predetermined value. And in the integration calculation of the refrigeration oil spill amount, when the detection unit detects that the two layers are separated, and when the detection unit does not detect that the two layers are separated, the calculation formula Is different. In this refrigeration apparatus, when the predetermined condition is satisfied and it is not detected by the detection unit that the two layers are separated, the oil return operation is performed, and the predetermined condition is satisfied and the detection unit performs the two-layer separation. When it is detected that the two layers are detected, the two-layer separation elimination operation is executed.

  The refrigeration apparatus according to a fourth aspect of the present invention is the refrigeration apparatus according to any one of the first to third aspects, wherein the control unit rotates the compressor during the two-layer separation elimination operation based on the refrigerant temperature around the accumulator. Determine the number. In this refrigeration apparatus, the rotation speed of the compressor during the two-layer separation elimination operation can be determined based on the refrigerant temperature around the accumulator.

  In the refrigeration apparatus according to the fifth aspect of the present invention, in the refrigeration apparatus according to the fourth aspect, the detection unit determines whether or not two layers are separated in the accumulator based on the number of rotations of the compressor. In this refrigeration apparatus, it can be determined whether or not two layers are separated in the accumulator based on the rotation speed of the compressor.

  In the refrigeration apparatus according to the sixth aspect of the present invention, in the refrigeration apparatus according to the fifth aspect, the detection unit determines whether or not two layers are separated in the accumulator based on the refrigerant temperature around the accumulator. In this refrigeration apparatus, it can be determined whether or not two layers are separated in the accumulator based on the refrigerant temperature around the accumulator.

  In the refrigeration apparatus according to the seventh aspect of the present invention, in the refrigeration apparatus according to the fifth aspect or the sixth aspect, the detection unit is configured to store two in the accumulator based on the suction dryness that is the dryness of the refrigerant sucked into the compressor. Determine whether the layers are separated. In this refrigeration apparatus, it can be determined whether or not two layers are separated in the accumulator based on the degree of dryness of suction.

  In the refrigeration apparatus according to the first aspect of the present invention, the two-layer separation in the accumulator can be eliminated by the control.

  In the refrigeration apparatus according to the second aspect of the present invention, the oil return operation is executed separately from the two-layer separation elimination operation.

  In the refrigeration apparatus according to the third aspect of the present invention, when the predetermined condition is satisfied and the two-layer separation is not detected by the detection unit, the oil return operation is executed and the predetermined condition is satisfied. And when it is detected by the detection part that two layers are separated, a two-layer separation elimination operation is executed.

  In the refrigeration apparatus according to the fourth aspect of the present invention, the rotation speed of the compressor during the two-layer separation elimination operation can be determined based on the refrigerant temperature around the accumulator.

  In the refrigeration apparatus according to the fifth aspect of the present invention, it is possible to determine whether or not two layers are separated in the accumulator based on the rotation speed of the compressor.

  In the refrigeration apparatus according to the sixth aspect of the present invention, it is possible to determine whether or not two layers are separated in the accumulator based on the refrigerant temperature around the accumulator.

  In the refrigeration apparatus according to the seventh aspect of the present invention, it is possible to determine whether or not two layers are separated in the accumulator based on the degree of suction dryness.

The figure which shows the refrigerant | coolant piping system of an air conditioning apparatus. The schematic block diagram of an accumulator. The figure which shows the relationship between a compressor rotation speed, suction | inhalation dryness, and the area | region which carries out two-layer separation within an accumulator. The figure which shows the relationship between the rotation speed of a compressor, suction | inhalation dryness, and the area | region of the environment which separates into two layers in an accumulator, and the area | region of the environment which does not separate into two layers. The figure for demonstrating the relationship between compressor rotation speed and evaporation temperature, and the presence or absence of the stirring of the fluid in an accumulator. The figure which shows the relationship between evaporation temperature, the oil concentration in an accumulator, and the presence or absence of two-layer separation in an accumulator. The figure which shows the relationship between a system oil rising rate and the oil concentration in an accumulator. The figure which shows the relationship between the accumulator outlet pipe dryness and the system oil rising rate which does not separate into two layers. The figure which shows the oil rising characteristic of a compressor.

  Hereinafter, an embodiment of an air-conditioning apparatus 10 as a refrigeration apparatus according to the present invention will be described based on the drawings.

(1) Overall Configuration of Air Conditioner 10 FIG. 1 is a diagram showing a refrigerant piping system of an air conditioner 10 according to an embodiment of the present invention. This air conditioner 10 is a distributed type air conditioner 10 of a refrigerant piping system, and air-conditions each room in a building by performing a vapor compression refrigeration cycle operation. The air conditioner 10 includes an outdoor unit 11 as a heat source unit and an indoor unit 12 as a utilization unit. The outdoor unit 11 and the indoor unit 12 are connected to each other by refrigerant communication pipes 13 and 14. A circuit is configured. The refrigerant circuit is filled with the refrigerant, and, as will be described later, the refrigerant is compressed, cooled / condensed, decompressed, heated / evaporated, and then compressed again. It has become. For example, R32 is used as the refrigerant. R32 is a low GWP refrigerant with a small global warming potential, and is a kind of HFC refrigerant. When R32 is used as the refrigerant, an ether-based synthetic oil having some compatibility with R32 is used as the refrigerating machine oil. In this air conditioner 10, since R32 is used as a refrigerant, depending on the oil content ratio, the solubility of the refrigerating machine oil enclosed with the refrigerant for lubrication of the compressor 20 during operation at low outside air depends on the oil content ratio. Tends to be very small.

(2) Detailed configuration of air conditioner 10 (2-1) Indoor unit 12
The indoor unit 12 is installed on the ceiling or side wall of each room, and is connected to the outdoor unit 11 via the refrigerant communication tubes 13 and 14. The indoor unit 12 mainly includes an indoor expansion valve 42 that is a decompressor and an indoor heat exchanger 50 that is a use-side heat exchanger. Here, although the indoor unit 12 has the indoor expansion valve 42, the present invention is not limited to this, and the indoor unit 12 may not have the indoor expansion valve 42.

  The indoor expansion valve 42 is an expansion mechanism for decompressing the refrigerant, and is an electric valve capable of adjusting the opening degree. The indoor expansion valve 42 has one end connected to the liquid refrigerant communication tube 13 and the other end connected to the indoor heat exchanger 50.

  The indoor heat exchanger 50 is a heat exchanger that functions as a refrigerant evaporator or a condenser. The indoor heat exchanger 50 has one end connected to the indoor expansion valve 42 and the other end connected to the gas refrigerant communication pipe 14.

  The indoor unit 12 includes an indoor fan 55 for sucking indoor air into the unit and supplying it to the room again, and exchanges heat between the indoor air and the refrigerant flowing through the indoor heat exchanger 50.

  In addition, the indoor unit 12 includes an indoor control unit 92 that controls various sensors and the operation of each unit constituting the indoor unit 12. The indoor control unit 92 includes a microcomputer, a memory, and the like provided for controlling the indoor unit 12, and controls with a remote controller (not shown) for individually operating the indoor unit 12. Exchange of a signal etc. is performed, and exchange of a control signal etc. is performed via the transmission line 90a with the outdoor control part 91 of the outdoor unit 11 mentioned later.

(2-2) Outdoor unit 11
The outdoor unit 11 is installed outside the building where each room where the indoor unit 12 is provided or in the basement of the building, and is connected to the indoor unit 12 via the refrigerant communication pipes 13 and 14. The outdoor unit 11 mainly includes a compressor 20, a four-way switching valve 15, an outdoor heat exchanger 30, an outdoor expansion valve 41, and an accumulator 70.

(2-2-1) Compressor 20
The compressor 20 is a hermetic compressor with a variable rotation speed driven by a compressor motor. Although the number of the compressors 20 is only one in the present embodiment, the present invention is not limited to this, and two or more compressors 20 may be connected in parallel according to the number of indoor units 12 connected. The compressor 20 sucks the refrigerant whose state changes between the gas and the liquid through the compressor accessory container 28 and compresses the sucked gas refrigerant.

(2-2-2) Four-way selector valve 15
The four-way switching valve 15 is a mechanism for switching the direction of refrigerant flow. During the cooling operation, the outdoor heat exchanger 30 functions as a refrigerant condenser compressed by the compressor 20 and the indoor heat exchanger 50 functions as a refrigerant evaporator cooled in the outdoor heat exchanger 30. In addition, the four-way switching valve 15 connects the refrigerant pipe 29 on the discharge side of the compressor 20 and one end of the outdoor heat exchanger 30, and the suction flow path 27 (including the accumulator 70) on the suction side of the compressor 20. And the gas side closing valve 18 are connected. Further, during the heating operation, the indoor heat exchanger 50 functions as a refrigerant condenser compressed by the compressor 20, and the outdoor heat exchanger 30 functions as a refrigerant evaporator cooled in the indoor heat exchanger 50. Therefore, the four-way switching valve 15 connects the refrigerant pipe 29 on the discharge side of the compressor 20 and the gas-side shut-off valve 18, and connects the suction flow path 27 and one end of the outdoor heat exchanger 30. The four-way switching valve 15 of the present embodiment is a four-way switching valve connected to the suction flow path 27, the refrigerant pipe 29 on the discharge side of the compressor 20, the outdoor heat exchanger 30, and the gas side shut-off valve 18.

(2-2-3) Outdoor heat exchanger 30
The outdoor heat exchanger 30 is a heat exchanger that functions as a refrigerant condenser or evaporator. One end of the outdoor heat exchanger 30 is connected to the four-way switching valve 15, and the other end is connected to the outdoor expansion valve 41.

(2-2-4) Outdoor fan 35
The outdoor unit 11 has an outdoor fan 35 for sucking outdoor air into the unit and discharging it to the outdoor again. The outdoor fan 35 is for exchanging heat between the outdoor air and the refrigerant flowing through the outdoor heat exchanger 30, and is rotated by an outdoor fan motor. The heat source of the outdoor heat exchanger 30 is not limited to outdoor air, and may be another heat medium such as water.

(2-2-5) Outdoor expansion valve 41
The outdoor expansion valve 41 is an expansion mechanism for decompressing the refrigerant, and is an electric valve capable of adjusting the opening degree. One end of the outdoor expansion valve 41 is connected to the outdoor heat exchanger 30, and the other end is connected to the liquid side closing valve 17.

(2-2-6) Liquid side closing valve 17 and gas side closing valve 18
The liquid side closing valve 17 is a valve to which a liquid refrigerant communication tube 13 for exchanging refrigerant between the outdoor unit 11 and the indoor unit 12 is connected. The gas side shut-off valve 18 is a valve to which a gas refrigerant communication tube 14 for exchanging refrigerant between the outdoor unit 11 and the indoor unit 12 is connected. The liquid side closing valve 17 and the gas side closing valve 18 of this embodiment are three-way valves provided with service ports.

(2-2-7) Accumulator 70
The accumulator 70 has a function of separating the refrigerant into gas and liquid and storing excess refrigerant. The accumulator 70 is disposed on the suction side of the compressor 20, more specifically, in the suction flow path 27 between the four-way switching valve 15 and the compressor 20. The accumulator 70 supplies the refrigerant returned from the indoor heat exchanger 50 or the outdoor heat exchanger 30 functioning as an evaporator through the first pipe 27a of the suction flow path 27 connected to the four-way switching valve 15 to the gas-liquid. To separate. Of the refrigerant separated into gas and liquid, the gas refrigerant is sent to the compressor 20. As shown in FIG. 2, the accumulator 70 includes a casing 71 that forms an internal space IS, an inlet pipe 72, and an outlet pipe 73.

  The casing 71 mainly includes a cylindrical main body 71a that is open at the top, bottom, a bowl-shaped upper lid 71b that closes the opening above the main body 71a, and a bowl-shaped lower lid 71c that blocks the opening below the main body 71a. It is composed of The inlet pipe 72 guides the refrigerant that has passed through the first pipe 27a of the suction flow path 27 into the internal space IS. The inlet pipe 72 penetrates the peripheral edge of the upper lid 71b, and the distal end opening 72a of the inlet pipe 72 is disposed above the internal space IS.

  The outlet pipe 73 of the accumulator 70 discharges the gas refrigerant separated in the internal space IS to the second pipe 27b of the suction flow path 27 connected to the compressor accessory container 28. The outlet pipe 73 is a J-shaped pipe, passes through the upper lid 71b, makes a U-turn at the lower part of the internal space IS, and the height position of the opening 73a at the upper end (tip) thereof is at the upper part of the internal space IS. To position. An oil return hole 73 b is formed in the U-turn portion in the lower part of the internal space IS of the outlet pipe 73. The oil return hole 73 b is a hole for returning the refrigeration oil accumulated together with the liquid refrigerant in the lower part of the internal space IS of the casing 71 to the compressor 20. Further, a pressure equalizing hole 73c is formed in a portion of the outlet pipe 73 near the upper lid body 71b.

  The outlet pipe 73 of the accumulator 70 and the compressor attached container 28 are connected by a second pipe 27 b of the suction flow path 27. The compressor attached container 28 and the compressor 20 are connected by a third pipe of the suction flow path 27. 27c.

(2-2-8) Outdoor control unit 91
The outdoor unit 11 has various sensors and an outdoor control unit 91. The outdoor control unit 91 includes a microcomputer, a memory, and the like provided for controlling the outdoor unit 11, and communicates with the indoor control unit 92 of the indoor unit 12 via a transmission line 90a. Exchange.

(2-3) Refrigerant communication pipes 13 and 14
The refrigerant communication pipes 13 and 14 are refrigerant pipes that are constructed on site when the outdoor unit 11 and the indoor unit 12 are installed at the installation location. Here, the liquid refrigerant communication tube 13 and the gas refrigerant communication tube 14 correspond to the refrigerant communication tube.

(3) Control device 90
The control device 90 of the air conditioner 10 includes an indoor control unit 92 and an outdoor control unit 91. The control device 90 has a function as an operation control means, and performs control in various operations of the air conditioner 10.

  Moreover, the outdoor control part 91 of the control apparatus 90 performs oil return operation | movement. Here, the oil return operation is an operation for returning the refrigeration oil flowing out from the compressor 20 to the system to the compressor 20 and is executed by controlling the rotation speed of the compressor 20. Specifically, in the oil return operation, the compressor 20 is driven for a predetermined time at a predetermined oil return rotational speed (for example, 40 rps). The predetermined oil return rotational speed is the rotational speed at which the desired amount of refrigeration oil out of the refrigeration oil that has flowed out of the compressor 20 into the system is returned to the compressor 20 by driving the compressor 20 for a predetermined time. It suffices if it is set, and it may be determined as appropriate by simulation, experiment, desktop calculation, or the like.

  Here, in this air conditioner 10, since R32 is used as a refrigerant, the solubility of the refrigerating machine oil enclosed with the refrigerant for lubricating the compressor 20 is very small at the low outside air temperature. Become. For this reason, on the low-pressure side in the refrigeration cycle, the solubility of the refrigeration oil greatly decreases due to a decrease in the refrigerant temperature, and the refrigerant R32 and the refrigeration oil are separated into two layers in the accumulator 70 that is at a low pressure in the refrigeration cycle. As a result, the refrigeration oil is less likely to return to the compressor 20. For example, when the compressor 20 is operated at a low rotational speed during heating operation or cooling operation at a low outside air temperature, the lower part of the internal space IS of the casing 71 is filled with liquid refrigerant, as shown in FIG. There is a tendency that the refrigerating machine oil separated from the liquid refrigerant collects in the upper part of the internal space IS. When such two-layer separation occurs, even if the oil return operation is performed, the fluid stored in the accumulator 70 cannot be sufficiently stirred with the fluid flowing out from the inlet pipe 72. Then, since the oil return hole 73b of the outlet pipe 73 of the accumulator 70 and the refrigerating machine oil are separated, the refrigerating machine oil accumulated in the internal space IS of the accumulator 70 cannot be returned to the compressor 20.

  In view of this, when the two-layer separation is performed in the accumulator 70, the outdoor control unit 91 performs a two-layer separation elimination operation for eliminating the two-layer separation. The outdoor control unit 91 includes a detection unit 91 a that detects whether or not two layers are separated in the accumulator 70. It is assumed that the detection of the two-layer separation by the detection unit 91a is performed every predetermined time. And the outdoor control part 91 performs two-layer separation elimination driving | operation, when it is detected by the detection part 91a that two-layer separation is carried out. In the two-layer separation elimination operation, the compressor 20 is driven for a predetermined time at a higher rotational speed than the oil return operation (hereinafter referred to as the two-layer separation elimination rotational speed). By executing the two-layer separation elimination operation, the liquid refrigerant and the refrigerating machine oil stored in the internal space IS of the accumulator 70 are stirred up and down, and the two-layer separation phenomenon in the accumulator 70 is eliminated. Since the two-layer separation elimination rotational speed is higher than the oil return rotational speed, the refrigeration oil that has flowed out of the compressor 20 into the system returns to the compressor 20 by executing the two-layer separation elimination operation. Become.

  Here, the oil return operation and the two-layer separation elimination operation are executed when a predetermined condition is satisfied. The predetermined condition may be a condition that serves as an index for suppressing insufficient lubrication of the compressor 20. For example, the integrated value of the refrigerating machine oil outflow amount that is the refrigerating machine oil amount flowing out of the compressor 20 is equal to or greater than a predetermined value. Is included. The predetermined value is set in the vicinity of the upper limit of the amount of discharged oil allowed for the reliability of the compressor 20. As an example of the refrigerating machine oil integration calculation, when two-layer separation is detected by the detection unit 91a, a condition that the current compressor rotation speed is smaller than the two-layer separation elimination rotation speed shown in FIG. While this is in progress, the following (Equation 1) and (Equation 2) are executed to update the integrated value of the refrigeration oil spillage (integrated refrigeration oil spillage), and while this condition is not satisfied, Do not update the integrated value of refrigeration oil spillage. On the other hand, when the two-layer separation is not detected by the detection unit 91a, while the condition that the current compressor rotation speed is smaller than the oil return rotation speed is satisfied, the following (Expression 1) and (Expression) By executing 2), the integrated value of the refrigerating machine oil outflow amount is updated, and the integrated value of the refrigerating machine oil outflow amount is not updated while this condition is not satisfied.

  (Formula 1): Refrigerating machine oil spill amount = current compressor rotation speed × coefficient × system oil rising rate (coefficient of compressor rotation speed) × Δt (sampling time)

  (Formula 2): Refrigerator oil spill amount integrated value = Refrigerator oil spill amount from the last reset to the present time + Refrigerator oil spill amount obtained from Equation 1

  Since the two-layer separation elimination rotational speed is larger than the oil return rotational speed, the calculation is performed using these equations, so that when the two-layer separation is detected, the refrigeration is faster than when the two-layer separation is not detected. The accumulated value of machine oil spillage increases. Here, when the condition that the integrated value of the refrigeration oil outflow amount is equal to or larger than the predetermined value is satisfied and the two-layer separation is not detected by the detection unit 91a, the oil return operation is executed. On the other hand, when the condition that the integrated value of the refrigerating machine oil outflow amount is equal to or greater than the predetermined value is satisfied and the two-layer separation is detected by the detection unit 91a, the two-layer separation elimination operation is executed.

  The detector 91a refers to the map shown in FIG. 3 and determines whether or not two layers are separated in the accumulator 70. The map shown in FIG. 3 determines the two-layer separation created based on the rotational speed of the compressor 20, the refrigerant temperature around the accumulator 70, the suction dryness that is the dryness of the refrigerant sucked into the compressor 20, and the like. The map is divided into a region A in an environment where two layers are separated, a region B in an environment where two layers are not separated, and a region C where two layers are separated. And the detection part 91a judges the presence or absence of two-layer separation of the accumulator 70 from the estimated suction dryness and the map shown in FIG. The suction dryness can be predicted from, for example, the discharge pipe temperature corrected by the outside air temperature, the condensation temperature, and the evaporation temperature. When the predicted suction dryness is in the region C in FIG. 3, the detection unit 91a determines that the two layers are separated. On the other hand, when the predicted suction dryness is in the region A or the region B in FIG. 3, the detection unit 91a determines that the two layers are not separated.

  The map shown in FIG. 3 is a map showing the relationship between the ease of two-layer separation taking into account the environment in the accumulator 70 as shown in FIG. 4 and the rotational speed of the compressor 20, and the accumulator 70 as shown in FIG. It is created by clarifying the region C where the two-layer separation occurs by combining the rotational speed map of the compressor 20 that can eliminate the two-layer separation by stirring the fluid stored in the inside. Here, the map as shown in FIG. 4 can be created as follows, for example. Looking at FIG. 6 showing the presence or absence of two-layer separation according to the oil concentration in the accumulator 70 and the refrigerant temperature around the accumulator 70 (here, the evaporation temperature Te), for example, the evaporation temperature Te is −30 ° C. In this case, it can be seen that if the oil concentration in the accumulator 70 is 2 wt% or less, the two layers are not separated in the accumulator 70. Incidentally, the oil concentration in the accumulator 70 can be obtained by the following equation.

Coil = OCR / {1- (1-OCR / 100) x}
Here, Coil is the oil concentration [wt%] of the accumulator 70, OCR is the system oil rising rate [wt%], and x is the dryness [−] of the outlet pipe 73 of the accumulator 70. Then, from FIG. 7 showing the oil concentration of the accumulator 70 when the system oil rising rate OCR and the dryness x of the outlet pipe 73 of the accumulator 70 are used as parameters, the accumulator is determined according to the dryness x of the outlet pipe 73 of the accumulator 70. The system oil rising rate OCR at which the oil concentration of 70 is 2 wt% can be obtained. FIG. 8 shows the relationship between the dryness x of the outlet pipe 73 of the accumulator 70 and the system oil rising rate OCR that is not separated into two layers. Here, it is known that the system oil rising rate increases as the rotational speed of the compressor 20 increases. For example, the characteristic can be expressed as shown in FIG. Then, FIG. 4 can be obtained by replacing the system oil increase rate OCR shown in FIG. 8 with the rotation speed of the compressor 20 corresponding to the system oil increase rate OCR with reference to FIG. 9.

  The two-layer separation elimination rotation speed of the two-layer separation elimination operation may be determined every time the two-layer separation elimination operation is performed, or may be set in advance to a predetermined rotation speed (for example, 60 rps). When the two-layer separation elimination rotation speed is determined every time the two-layer separation elimination operation is performed, for example, referring to FIG. 5, the refrigerant temperature (evaporation) around the accumulator 70 when it is determined that a predetermined condition is satisfied. The rotation speed obtained by adding a predetermined value (for example, 10 rps) to the lower limit value of the rotation speed of the compressor 20 capable of stirring the fluid in the accumulator 70 obtained from the temperature) is compared with the oil return rotation speed. The rotation speed is determined as the two-layer separation elimination rotation speed.

  In addition, when the defrost operation is executed before it is determined that the predetermined condition is satisfied, and when the oil return operation or the two-layer separation elimination operation is executed, the integrated value of the refrigeration machine oil outflow amount is reset. . Here, when the defrost operation is executed, the integrated value of the refrigerating machine oil outflow amount is reset, so the defrost operation is replaced with the oil return operation or the two-layer separation elimination operation.

(4) Features (4-1)
Conventionally, there is a refrigeration apparatus including an accumulator having a function of temporarily storing refrigerant returned to the compressor and suppressing suction of liquid refrigerant into the compressor.

  Here, in the compressor, a part of the refrigerating machine oil stored in the compressor may be discharged together with the gas refrigerant and flow out to the system. When the refrigeration oil is discharged from the compressor together with the gas refrigerant in the refrigeration apparatus including the accumulator, the discharged refrigeration oil is accumulated in the accumulator together with the liquid refrigerant before returning to the compressor through the refrigeration circuit. There is. At this time, if the liquid refrigerant and the refrigerating machine oil are separated into two layers in the accumulator, it becomes difficult for the refrigerating machine oil accumulated in the accumulator to return to the compressor, and the refrigerating machine oil in the compressor is insufficient. The machine will malfunction due to poor lubrication.

  In the present embodiment, when the detection unit 91a detects that the two layers are separated, the two-layer separation elimination operation is executed. For this reason, the shortage of refrigerating machine oil of the compressor 20 due to the two-layer separation in the accumulator 70 can be solved.

  In the present embodiment, the two-layer separation in the accumulator 70 can be eliminated by the control of executing the two-layer separation elimination operation.

(4-2)
In the present embodiment, when the predetermined condition is satisfied and it is not detected that the two-layer separation is detected by the detection unit 91a, the refrigerating machine oil flowing out from the compressor 20 to the system is supplied to the compressor 20. An oil return operation is performed to return. For this reason, even if the two layers are not separated by the accumulator 70, the operation of returning the refrigeration oil to the compressor 20 can be executed.

  Further, in the present embodiment, the oil return rotation speed that is the rotation speed of the compressor 20 during the oil return operation is lower than the two-layer separation elimination rotation speed that is the rotation speed of the compressor 20 during the two-layer separation elimination operation. It is set to be. Thereby, refrigeration oil can be efficiently returned to the compressor 20, and the amount of power consumption can be suppressed more than when the two-layer separation elimination operation is executed.

(4-3)
In the present embodiment, the two-layer separation elimination operation is performed when the predetermined condition is satisfied and the detection unit 91a detects that the two layers are separated. In the two-layer separation elimination operation, the compressor 20 is driven at a higher rotational speed than in the oil return operation. Therefore, by executing the two-layer separation elimination operation, the same effect as that in the oil return operation can be produced. it can. Thereby, the shortage of refrigerating machine oil of the compressor 20 can be solved.

(4-4)
Here, when the two layers are separated by the accumulator 70, the amount of refrigerating machine oil returning from the accumulator 70 to the compressor 20 is smaller than when the two layers are not separated. Then, even if the amount of the refrigerating machine oil discharged from the compressor 20 is the same between the case where the two layers are separated by the accumulator 70 and the case where the two layers are not separated, the refrigerating machine oil existing in the compressor 20 There will be a difference in quantity.

  In the present embodiment, the predetermined condition that is the starting condition for the two-layer separation elimination operation and the oil return operation includes a condition that the integrated value of the refrigerating machine oil outflow amount is a predetermined value or more. In the integration calculation of the refrigerating machine oil, the operation is performed so that the integrated value of the refrigerating machine oil outflow amount is larger when the two-layer separation is detected than when the two-layer separation is not detected. Thereby, it is possible to reduce the risk of the refrigeration oil shortage of the compressor 20 due to the erroneous estimation of the amount of refrigeration oil flowing out of the compressor 20.

(4-5)
Here, the rotational speed of the compressor 20 that can eliminate the two-layer separation by stirring the fluid stored in the accumulator 70 and the refrigerant temperature around the accumulator 70 are correlated (FIG. 5). reference).

  In this embodiment, when the predetermined two-layer separation state elimination rotational speed is determined based on the refrigerant temperature around the accumulator 70, the rotational speed of the compressor 20 is not increased excessively, and the internal speed of the accumulator 70 is increased. Two-layer separation can be eliminated.

(4-6)
Here, the presence or absence of the two-layer separation is related to the refrigerant temperature around the accumulator 70 and the oil concentration in the fluid accumulated in the accumulator 70. For example, by determining the lower limit value of the refrigerant temperature around the accumulator 70, the accumulator 70 The oil concentration in the accumulator 70 that does not separate into two layers within 70 can be obtained.

  Further, the oil concentration in the accumulator 70 can be obtained from the oil rising rate from the compressor 20 and the suction dryness. And based on this, the oil rising rate which becomes the oil concentration in the accumulator 70 which does not separate into two layers in the accumulator 70 can be obtained according to the suction dryness. Further, there is a characteristic that the oil rising rate increases as the rotational speed of the compressor 20 increases. Then, the theoretical rotation speed of the compressor 20 which does not separate into two layers in the accumulator 70 with respect to the suction dryness can be obtained. Therefore, it is possible to determine whether or not the two layers are separated in the accumulator 70 based on the suction dryness and the rotation speed of the compressor 20.

  On the other hand, when the rotation speed of the compressor 20 is large, the fluid stored in the accumulator 70 is agitated, and the two-layer separation in the accumulator 70 is eliminated. For this reason, there is a risk that it is erroneously determined that the two-layer separation has occurred even though the two-layer separation has been eliminated by stirring, only by the determination based on the suction dryness and the rotation speed of the compressor 20. There is.

  In the present embodiment, the detection unit 91a determines whether or not two layers are separated in the accumulator 70 from the suction dryness and the map shown in FIG. Therefore, it is possible to accurately detect whether or not the two layers are separated in the accumulator 70.

(5) Modification (5-1)
In the above embodiment, whether or not two layers are separated in the accumulator 70 is determined from the suction dryness and the map shown in FIG.

  Instead of this, it may be determined whether or not the two layers are separated in the accumulator 70 based only on the rotational speed of the compressor 20. For example, referring to FIG. 5, if the rotation speed of the compressor 20 is less than 60 rps, it may be determined that the two layers are separated, and if it is 60 rps or more, it may be determined that the two layers are not separated. Moreover, with reference to FIG. 4, the presence or absence of two-layer separation may be determined from the suction dryness and the rotational speed of the compressor 20. Furthermore, with reference to FIG. 4 and FIG. 5, the presence or absence of two-layer separation may be determined from the rotational speed of the compressor 20, the suction dryness, and the evaporation temperature.

(5-2)
In the above embodiment, the refrigerating machine oil outflow amount is calculated from Equation 1 and Equation 2 regardless of whether or not the two-layer separation is detected by the detector 91a. Instead, in the calculation of the refrigeration oil spillage amount, the calculation is performed when the detection unit 91a detects that the two-layer separation is detected and when the two-layer separation is not detected. The formula may be different. For example, the coefficient in Equation 1 is different so that the integrated value of the refrigeration oil outflow amount is larger when the two-layer separation is detected by the detection unit 91a than when the two-layer separation is not detected. Also good.

  According to the present invention, since the two-layer separation in the accumulator can be eliminated by the control, application to a refrigeration apparatus including a compressor and an accumulator is effective.

10 Air conditioning equipment (refrigeration equipment)
20 Compressor 70 Accumulator 91 Outdoor control unit (control unit)
91a detector

JP2013-245836A

Claims (7)

A compressor (20) having a variable rotation speed for compressing a refrigerant whose state changes between gas and liquid;
An accumulator (70) that is provided on the suction side of the compressor and stores excess refrigerant;
A control unit (91) for controlling the driving of the compressor;
With
The controller is
A detector (91a) for detecting whether or not two layers are separated in the accumulator;
When it is detected by the detection unit that the two-layer separation is performed, a two-layer separation elimination operation for driving the compressor at a higher rotational speed than an oil return operation is performed.
Refrigeration equipment (10). The control unit performs the oil return operation when a predetermined condition is satisfied and the detection unit does not detect that the two-layer separation is performed.
The refrigeration apparatus according to claim 1. The control unit performs the two-layer separation elimination operation when the predetermined condition is satisfied,
The predetermined condition includes a condition that an integrated value of the refrigeration oil outflow amount that is the amount of refrigeration oil flowing out of the compressor is equal to or greater than a predetermined value,
In the calculation of the refrigeration oil outflow, when the detection unit detects that the two layers are separated, and when the detection unit does not detect that the two layers are separated. , Arithmetic expressions are different,
The refrigeration apparatus according to claim 2. The control unit determines the rotation speed of the compressor during the two-layer separation elimination operation based on the refrigerant temperature around the accumulator.
The refrigeration apparatus according to any one of claims 1 to 3. The detection unit determines whether or not the two layers are separated in the accumulator based on the rotation speed of the compressor.
The refrigeration apparatus according to claim 4. The detection unit determines whether or not the two layers are separated in the accumulator based on the refrigerant temperature around the accumulator.
The refrigeration apparatus according to claim 5. The detection unit determines whether or not the two layers are separated in the accumulator based on a suction dryness that is a dryness of a refrigerant sucked into the compressor.
The refrigeration apparatus according to claim 5 or 6.

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