JP4454323B2 - Refrigeration system - Google Patents

Description

  The present invention relates to a refrigeration system including a plurality of compressors having different refrigerant discharge amounts.

  In recent years, a refrigeration system has been proposed that includes an air conditioning system that performs indoor air conditioning of a store such as a convenience store, and a cooling system that cools a refrigeration case and a refrigeration case as a cooling storage facility provided in the store. (For example, Patent Document 1).

Since the refrigerant evaporating pressure in the refrigeration case is lower than the refrigerant evaporating pressure in the refrigeration case, when the refrigeration case and the refrigeration case are cooled by one refrigerant circuit, the refrigerant pressure after the refrigeration case is changed to the refrigeration case. It is necessary to increase the pressure to the subsequent refrigerant pressure and to merge with the refrigerant after the refrigeration case. Therefore, the cooling system section includes a cooling compressor (first compressor) whose main role is refrigerant circulation, and a boosting compressor (second compressor) for increasing the refrigerant pressure after the refrigeration case. It is conceivable to provide
JP 2002-174470 A

  However, since the boosting compressor has a smaller output and a smaller refrigerant discharge amount than the cooling compressor, the amount of oil that flows out of the apparatus when mixed with the refrigerant is small. Therefore, as the operation of the refrigeration system is continued, there is a problem that the oil flowing out from the cooling compressor having a large output is biased and accumulates in the boosting compressor having a small output.

  Therefore, the present invention has been made in view of the above-described circumstances, and provides a refrigeration system capable of eliminating the accumulation of oil from a compressor having a large discharge amount in a compressor having a small discharge amount. The purpose is that.

In order to solve the above-mentioned problem, the present invention is a first compressor and a first compressor which is connected in series or in parallel to the first compressor and has a smaller refrigerant discharge amount than the first compressor. 2 and an oil separator connected to the refrigerant discharge side of the second compressor. The second compressor houses a motor on the upper side of the hermetic container and a compression element on the lower side. An oil discharge path for discharging oil stored in a high-pressure state inside the sealed container to the oil separator is connected between the compression element and the motor, and the oil separator and the second compressor are connected. It is characterized in that it is connected to the suction side by a thin tube .

  In this case, the oil discharge path may be connected to a storage upper limit position of oil stored in the second compressor.

  In addition, a cooling system part that cools the inside of the cooling storage facility including the refrigeration case and the refrigeration case is provided, and the cooling system part includes a first compressor, a second compressor, and an oil discharge path. Also good.

  In this case, the cooling system unit includes an outdoor unit and a booster unit in addition to the freezing case and the refrigeration case, the first unit is provided in the outdoor unit, and the second compressor and the oil discharge path are provided in the booster unit. It is good also as a structure which provided.

  Furthermore, the first compressor is a cooling compressor whose main role is refrigerant circulation, and the second compressor boosts the pressure of the refrigerant passing through the refrigeration case to the refrigerant pressure passing through the refrigeration case. It is good also as a structure which is a compressor for pressure | voltage rise for this.

  In the present invention, it is possible to prevent oil from a compressor having a large discharge amount from being biased and accumulated inside the compressor having a small discharge amount.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a system configuration of a refrigeration system 1 according to the present embodiment. This refrigeration system 1 realizes, for example, indoor air conditioning in a store 2 (indoor) of a convenience store, and in-case cooling of a refrigerated case 3 or a refrigerated case 4 as a cooling storage facility installed therein. . In the refrigerated case 3, the inside of the case is cooled to a refrigerated temperature (+ 3 ° C. to + 10 ° C.), beverages and refrigerated foods are displayed, and the freezer case 4 has a freezing temperature (−10 ° C. to −20 ° C.). It is cooled and frozen food or frozen desserts are displayed.

  The refrigeration system 1 includes an air conditioning system unit 6 that performs air conditioning in the store 2 and a cooling system unit 8 that cools the refrigeration case 3 and the refrigeration case 4 in the case. The air conditioning system unit 6 includes an indoor unit 11 installed on the ceiling of the store 2 and an outdoor unit 12 installed outside the store. An air conditioning refrigerant circuit 7 is provided between the indoor unit 11 and the outdoor unit 12. This air-conditioning refrigerant circuit 7 is air-conditioned by a use-side heat exchanger 27 installed in the indoor unit 11, a heat-source side heat exchanger 16 installed in the outdoor unit 12, and air-conditioning compressors 13A and 13B. Cycle.

  The air conditioning compressor 13A is a compressor for inverter control, and the air conditioning compressor 13B is a compressor for constant speed operation. These air-conditioning compressors 13A and 13B are connected in parallel, and the discharge sides of the air-conditioning compressors 13A and 13B are joined via check valves 5A and 5B, and one inlet of the four-way valve 14 via the oil separator 10 Connected to. One outlet of the four-way valve 14 is connected to the inlet of the heat source side heat exchanger 16. The heat source side heat exchanger 16 includes an inlet side 16A having a relatively small flow resistance composed of a large number of parallel pipes and an outlet side 16B in which these are aggregated into a small number of parallel pipes or a single pipe. The outlet on the outlet side 16B of the heat source side heat exchanger 16 is connected to the inlet of the expansion valve 18 via the check valve 5C and the expansion valve 17 connected in parallel. The outlet of the expansion valve 18 is an indoor unit. 11 is connected to the entrance of the use side heat exchanger 27.

  The outlet of the use side heat exchanger 27 is connected to the other inlet of the four-way valve 14 across the outdoor unit 12, and the other outlet of the four-way valve 14 is connected to the accumulator 23 via the check valve 5D. The outlet of the accumulator 23 is connected to the suction side of the air conditioning compressors 13A and 13B. The check valve 5D has a forward direction on the accumulator 23 side. The piping between the expansion valves 17 and 18 is connected to the inlet of the expansion valve 19, and the outlet of the expansion valve 19 is connected to the inlet of the air conditioning side passage 21 </ b> A of the cascade heat exchanger 21. The outlet of the air conditioning side passage 21A of the cascade heat exchanger 21 is connected to the suction side of the air conditioning compressors 13A and 13B via an accumulator 23.

  The outdoor air conditioning controller 26 is configured by a general-purpose microcomputer, and controls the equipment of the air conditioning system unit 6 on the outdoor unit 12 side based on the outside air temperature and the refrigerant pressure. The indoor air conditioning controller 28 is composed of a general-purpose microcomputer, and controls the equipment on the indoor unit 11 side based on a user instruction transmitted from a remote controller (not shown) and input via a receiving unit (not shown). Control or data communication of information in accordance with a user instruction to the outdoor air conditioning controller 26 is performed. The blower 24 is a blower that blows outside air to the heat source side heat exchanger 16, and the blower 15 is a blower that sends room air to the use side heat exchanger 27.

  On the other hand, the cooling system unit 8 includes a refrigeration case 3 or a refrigeration case 4 serving as a cooling storage facility, and a cooling refrigerant circuit 9 provided between the outdoor unit 12. The cooling refrigerant circuit 9 includes a refrigeration evaporator 43 provided in the refrigeration case 3, a refrigeration evaporator 49 provided in the refrigeration case 4, and a condenser (heat exchanger) 38 installed in the outdoor unit 12. The refrigeration cycle is performed by the cooling compressor 37 (first compressor) and the boosting compressor 54 (second compressor).

  The cooling compressor 37 mainly plays a role of refrigerant circulation, and the discharge side of the cooling compressor 37 is connected to one inlet of a four-way valve 39 via an oil separator 31. One outlet is connected to the inlet of the condenser 38. The condenser 38 includes an inlet side 38A having a relatively small flow resistance composed of a large number of parallel pipes, and an outlet side 38B in which these are aggregated into a small number of parallel pipes or a single pipe. The outlet on the outlet side 38B of the condenser 38 is connected to the inlet of the receiver tank 36, and the outlet of the receiver tank 36 is connected to one inlet of the four-way valve 41. That is, the receiver tank 36 is connected to the refrigerant downstream side of the condenser 38.

  One outlet of the four-way valve 41 is connected to the inlet of the case side passage 21 </ b> B of the cascade heat exchanger 21. The cascade heat exchanger 21 exchanges heat between the refrigerant that passes through the air conditioning side passage 21A and the case side passage 21B that are formed inside, thereby cooling the low pressure side of the air conditioning refrigerant circuit 7 and cooling it. The refrigerant circuit 9 is thermally connected to the high pressure side.

  The outlet of the case side passage 21 </ b> B of the cascade heat exchanger 21 is connected to the other inlet of the four-way valve 39, and the other outlet of the four-way valve 39 is connected to the other inlet of the four-way valve 41. The other outlet of the four-way valve 41 exits from the outdoor unit 12 and branches into the room 2 (inside the store). One of the branched pipes is connected to the inlet of the refrigeration evaporator 43 via an electromagnetic valve 46 and an expansion valve 44. The other is connected to the inlet of the refrigeration evaporator 49 through the electromagnetic valve 52 and the expansion valve 51.

  The outlet of the refrigeration evaporator 49 is connected to the suction side of the boosting compressor 54 via the check valve 30 (the check valve 30 is in the forward direction on the boosting compressor 54 side). The boosting compressor 54 is for boosting the pressure of the refrigerant that has passed through the refrigeration case 4 to the refrigerant pressure that has passed through the refrigeration case 3, has a smaller output than the cooling compressor 37, and has a refrigerant discharge amount. There are few compressors. Therefore, the amount of oil mixed with this refrigerant and flowing out of the machine is small. The discharge side of the pressurizing compressor 54 is connected to one inlet of the four-way valve 42 via the oil separator 45, and one outlet of the four-way valve 42 is connected to the outlet side of the refrigeration evaporator 43. It is connected to the suction side of the cooling compressor 37. That is, the boosting compressor 54 and the cooling compressor 37 are connected in series on the refrigerant circuit. The other inlet of the four-way valve 42 is connected to a pipe line on the inlet side of the pressurizing compressor 54, and the other outlet of the four-way valve 42 is connected to the case side passage of the cascade heat exchanger 21 via a check valve 61. It is merged with a pipe line on the inlet side of 21B. The check valve 61 has a forward direction on the cascade heat exchanger 21 side.

  In the above configuration, among the components of the cooling system section 8, the boosting compressor 54, the check valve 30, the oil separator 45, and the four-way valve 42 are separate units from the outdoor unit 12 that houses the cooling compressor 37. Of the booster unit 22. The booster unit 22 is arranged at an arbitrary position such as an outer wall or the ground of a convenience store. In addition, the four-way valve 42 housed in the booster unit 22 is switched so that the refrigerant (cooling refrigerant) discharged from the refrigeration evaporator 43 and the refrigeration evaporator 49 is supplied to each compressor of the cooling system unit 8. A bypass path that leads to the inlet of the cascade heat exchanger 21 can be formed without going through (the cooling compressor 37 or the boosting compressor 54). According to this, when one of the cooling compressor 37 and the boosting compressor 54 fails, the refrigerant flowing out of the refrigeration evaporator 43 and the freezing evaporator 49 fails by switching the four-way valve 42. It can be led to the inlet of the cascade heat exchanger 21 via a compressor that is not.

  The outdoor side cooling controller 32 is composed of a general-purpose microcomputer, and controls the equipment of the cooling system unit 8 on the outdoor unit 12 side based on the outside air temperature and the refrigerant pressure. Moreover, the refrigeration case controller 50 is comprised with a general purpose microcomputer, and controls the apparatus of the cooling system | strain part 8 based on the case internal temperature of the storage facility for refrigeration (refrigeration case 3). The refrigeration case controller 55 is composed of a general-purpose microcomputer, and controls the equipment of the cooling system unit 8 based on the case internal temperature of the refrigeration storage facility (refrigeration case 4). The blower 35 is a blower that blows outside air to the condenser 38, the blower 20 is a blower that sends the air in the case of the refrigeration case 3 to the condenser 38, and the blower 25 is refrigerated to the freezing evaporator 49. A blower for sending air inside the case 4.

  The refrigeration system 1 has a main controller 56. The main controller 56 is composed of a general-purpose microcomputer, and performs data communication with the outdoor air conditioning controller 26, the indoor air conditioning controller 28, the outdoor cooling controller 32, the refrigeration case controller 50, and the refrigeration case controller 55. It performs overall control. In the refrigeration system 1, different refrigerants are used in the air conditioning refrigerant circuit 7 and the cooling refrigerant circuit 9. For example, R410A is used in the air conditioning refrigerant circuit 7, and R410A is used in the cooling refrigerant circuit 9. R404A having a higher boiling point is used. Thus, since this refrigeration system 1 can use the optimal refrigerant | coolant for each refrigerant circuit, respectively, the freedom degree of circuit design can be made high.

  Next, the operation of the refrigeration system 1 when the refrigeration system 1 cools the room 2 and cools the refrigeration case 3 and the refrigeration case 4 will be described.

  First, when the main controller 56 performs the above operation, data on the optimum operation pattern is transferred to the outdoor air conditioning controller-26, the indoor air conditioning controller-28, the outdoor cooling controller 32, the refrigeration case controller 50, and the refrigeration case controller 55. Send.

  Based on the transmission data from the main controller 56, the outdoor air-conditioning controller 26 communicates the one inlet of the four-way valve 14 with one outlet and the other inlet with the other outlet, as shown in FIG. . The expansion valve 17 is fully opened. Then, the air conditioning compressors 13A and 13B are operated. It is assumed that the outdoor air conditioning controller -26 adjusts the operating frequency of the air conditioning compressor 13A to control the capacity.

  When the air-conditioning compressors 13A and 13B are operated, the high-temperature and high-pressure gas refrigerant discharged from the discharge sides of the air-conditioning compressors 13A and 13B passes through the four-way valve 14 and the inlet side 16A of the heat source side heat exchanger 16. to go into. Outside air is ventilated by the air blower 24 to the heat source side heat exchanger 16, and the refrigerant dissipates heat here to be condensed and liquefied. That is, in this case, the heat source side heat exchanger 16 functions as a condenser. The liquid refrigerant exits from the outlet side 16B from the inlet side 16A of the heat source side heat exchanger 16 via the outlet side 16B. And after passing the expansion valve 17, it branches. One of the branched branches reaches the expansion valve 18, where it is throttled to a low pressure (decompression), and then flows into the use side heat exchanger 27 where it evaporates.

  The air in the room 2 (inside the store) is ventilated by the blower 15 through the use side heat exchanger 27, and the air in the room 2 is cooled by an endothermic action due to evaporation of the refrigerant. Thereby, the room 2 (inside the store) is cooled. The low-temperature gas refrigerant that has exited from the use-side heat exchanger 27 passes through the four-way valve 14, the check valve 5 </ b> D, and the accumulator 23 in order and repeats circulation that is sucked into the suction side of the air-conditioning compressors 13 </ b> A and 13 </ b> B.

  The indoor side air conditioning controller-28 uses the temperature of the use side heat exchanger 27 and the air temperature sucked into the use side heat exchanger 27 so that the temperature of the room 2 (inside the store) is set to a preset set temperature. The blower 15 that ventilates the heat exchanger 27 is controlled. Information from the indoor air conditioning controller-28 is transmitted to the main controller 56, and the outdoor air conditioning controller 26 controls the operation of the air conditioning compressors 13A and 13B based on this information.

  The other refrigerant branched after passing through the check valve 5C reaches the expansion valve 19, where it is throttled to a low pressure (decompression), and then flows into the air conditioning side passage 21A of the cascade heat exchanger 21 where it evaporates. . The cascade heat exchanger 21 is cooled by the endothermic action due to the evaporation of the refrigerant in the air-conditioning refrigerant circuit 7 and becomes a low temperature. The low-temperature gas refrigerant exiting the cascade heat exchanger 21 repeats circulation through the accumulator 23 and sucked into the suction side of the air-conditioning compressors 13A and 13B.

  The outdoor air conditioning controller -26 is a room temperature, refrigerant at the entrance / exit of the use side heat exchanger 27 so that the temperature of the room 2 (inside the store) becomes a set temperature set by the user using a remote control device (remote control). Based on the temperature or the temperature of the use side heat exchanger 27, the operating frequency of the air conditioning compressor 13A and the opening of the expansion valve 18 are adjusted. In addition, the outdoor air conditioning controller-26 expands the expansion valve so that the difference between the inlet temperature TC1 and the outlet temperature TC2 of the case side passage 21B of the cascade heat exchanger 21 becomes a preset temperature difference (for example, 20 ° C.). The supercooling control is performed by adjusting the valve opening degree of 19.

  Further, the indoor side air conditioning controller-28 sets the temperature of the room 2 (in the store) to a preset temperature based on the temperature of the use side heat exchanger 27 and the air temperature sucked into the use side heat exchanger 27. The blower 15 that ventilates the use side heat exchanger 27 is controlled.

  On the other hand, the outdoor side cooling controller 32 causes the one inlet of the four-way valve 39 of the cooling refrigerant circuit 9 of the cooling system unit 8 to communicate with one outlet and the other inlet to communicate with the other outlet. Further, the one inlet of the four-way valve 41 is communicated with one outlet, and the other inlet is communicated with the other outlet. Then, the cooling compressor 37 and the boosting compressor 54 are operated. The high-temperature and high-pressure gas refrigerant discharged from the cooling compressor 37 is separated by the oil separator 31 and then enters the inlet side 38A of the condenser 38 through the four-way valve 39. Outside air is also passed through the condenser 38 by the blower 35, and the refrigerant flowing into the condenser 38 dissipates heat and condenses there. The solenoid valve 47 is fully opened.

  The refrigerant that has passed through the inlet side 38A of the condenser 38 reaches the outlet side 38B and exits there. The refrigerant from the condenser 38 enters the receiver tank 36 from the inlet side of the receiver tank 36, and is temporarily stored therein to separate the gas / liquid. The separated liquid refrigerant exits from the outlet of the receiver tank 36, passes through the four-way valve 41, and then enters the case side passage 21 </ b> B of the cascade heat exchanger 21. The refrigerant in the cooling refrigerant circuit 9 that has entered the case side passage 21B is cooled by the cascade heat exchanger 21 that is at a low temperature due to the evaporation of the refrigerant in the air conditioning refrigerant circuit 7 as described above, and the supercooled state further increases. . More specifically, as described above, the outdoor air conditioner controller -26 cools by a preset temperature difference (for example, 20 ° C.). Since the receiver tank 36 is disposed immediately after the condenser 38, it is possible to eliminate heat loss during supercooling and to adjust the amount of refrigerant.

  The refrigerant supercooled in the cascade heat exchanger 21 is branched after sequentially passing through the four-way valve 39 and the four-way valve 41, and one of the refrigerant passes through the electromagnetic valve 46 to the expansion valve 44, where it is throttled ( Pressure reduction), it flows into the refrigeration evaporator 43 and evaporates there. In the refrigeration evaporator 43, the air in the case of the refrigeration case 3 is ventilated and circulated by the blower 20, and the air in the case is cooled by an endothermic action due to evaporation of the refrigerant. Thereby, in-case cooling of the refrigeration case 3 is performed. The low-temperature gas refrigerant exiting the refrigeration evaporator 43 reaches the outlet side of the oil separator 45 of the pressurizing compressor 54.

  The other refrigerant branched out of the cascade heat exchanger 21 passes through the electromagnetic valve 52 and reaches the expansion valve 51. After being throttled (decompression), it flows into the refrigeration evaporator 49 where it evaporates. The air in the case of the refrigeration case 4 is also ventilated and circulated by the blower 25 to the refrigeration evaporator 49, and the case internal air is cooled by the endothermic action due to the evaporation of the refrigerant, and the refrigeration case 4 is cooled in the case. .

  The low-temperature gas refrigerant that has exited the freezing evaporator 49 is branched, and one of the refrigerant passes through the check valve 30 and reaches the boosting compressor 54 where it is compressed and boosted to a pressure on the outlet side of the refrigeration evaporator 43. After being discharged from the pressurizing compressor 54, the oil is separated by the oil separator 45, and then merged with the refrigerant from the refrigeration evaporator 43 through the four-way valve 42. The merged refrigerant repeats circulation that is sucked into the suction side of the compressor 37. The other flows into the cascade heat exchanger 21 via the four-way valve 42 and the check valve 61.

  The refrigeration case controller 50 is configured such that the temperature in the case of the refrigeration case 3, the temperature of the discharged chilled air that has passed through the refrigeration evaporator 43, the temperature of the intake cold air to the refrigeration evaporator 43, the refrigerant temperature on the outlet side of the refrigeration evaporator 43, The valve opening degree of each expansion valve 44 is controlled based on the temperature of the refrigeration evaporator 43. Thereby, it is set as the appropriate superheat degree (constant superheat degree), maintaining the inside of the case of the refrigeration case 3 cooled to the refrigeration temperature mentioned above.

  Further, the refrigeration case controller 55 is configured such that the temperature inside the case of the refrigeration case 4, the temperature of the discharged cold air passing through the refrigeration evaporator 49, or the temperature of the suction cold air into the refrigeration evaporator 49, and the refrigerant temperature on the outlet side of the refrigeration evaporator 49. Alternatively, the valve opening degree of the expansion valve 51 is controlled based on the temperature of the refrigeration evaporator 49. Thus, while maintaining the inside of the case of the refrigeration case 4 at the above-described refrigeration temperature, an appropriate degree of superheat (constant superheat) is obtained.

  The operating frequency of the cooling compressor 37 is controlled based on the suction side pressure (low pressure of the cooling refrigerant circuit 9). When all the expansion valves 44 and 51 are fully closed, the expansion valves 44 and 51 are stopped, and when one of them is opened, the operation is performed.

  Thus, since the high-pressure side refrigerant of the cooling refrigerant circuit 9 can be supercooled by the low-pressure side refrigerant of the air-conditioning refrigerant circuit 7 flowing through the air-conditioning side passage 21A of the cascade heat exchanger 21, the refrigeration case 3 or the refrigeration case The cooling capacity in the evaporators 43 and 49 and the operation efficiency of the cooling refrigerant circuit 9 are improved. In this case, since the refrigerant on the high pressure side of the cooling refrigerant circuit 9 flows to the case side passage 21B of the cascade heat exchanger 21 via the condenser 38, the degree of superheat of the air conditioning refrigerant circuit 7 is also maintained in an appropriate range. it can.

  Further, the pressure of the refrigerant exiting from the freezing evaporator 49 of the cooling refrigerant circuit 9 is lower than that of the refrigerant exiting the refrigeration evaporator 43 because of its lower evaporation temperature. The refrigerant is compressed by the pressure-increasing compressor 54 before being joined with the refrigerant, so that the inside of the refrigeration case 3 and the refrigeration case 4 is cooled smoothly by the evaporators 43 and 49, respectively. 9 can be operated without any trouble by adjusting the pressure of the refrigerant sucked into the cooling compressor 37.

  2 is a perspective view showing the appearance of the outdoor unit 12, and FIG. 3 is a top view of the outdoor unit 12 with the top panel 12A removed. The outdoor unit 12 includes air conditioning system side components (air conditioning compressors 13A and 13B, an accumulator 23, an oil separator 10, a heat source side heat exchanger 16, other than components installed in the indoor unit 11 in the air conditioning system unit 6. Among the cooling system unit 8, the cooling system side component (compressor 37, oil separator) other than the components arranged in the refrigeration case 3, the freezing case 4, and the booster unit 22. 31, receiver tank 36, condenser 38, blower 35, outdoor cooling controller 32, and the like).

  More specifically, in the outdoor unit 12, as shown in FIG. 3, the blower 24 is disposed on the left side when viewed from the front side, and air conditioning system side components other than the blower 24 are disposed around the blower 24. In addition, a blower 35 is arranged on the right side when viewed from the front side, and cooling system side components other than the blower 35 are arranged around the blower 35. Here, in the space on the front side between the blower 24 and the blower 35, the air-conditioning compressors 13A and 13B are arranged on the substantially lower left side, the compressor 37 is installed on the lower right side, and the chamber on the upper left side. The outdoor air conditioning controller -26 and the outdoor cooling controller 32 are arranged on the upper right side. That is, in the outdoor unit 12, the air-conditioning system side component and the cooling system-side component are arranged separately on the left and right, and by arranging the respective system-side components on the left and right in this way, Assembling and maintenance on the cooling system side can be easily performed, and the piping length on the air conditioning system side and the piping length on the cooling system side can be shortened.

  By the way, as described above, since the boosting compressor 54 has a smaller output than the cooling compressor 37, the amount of refrigerant discharged is small, and therefore the amount of oil flowing out of the apparatus mixed with the refrigerant is small. For this reason, in the refrigeration system 1, as the operation of the cooling system unit 8 is continued, the oil discharged from the cooling compressor 37 having a large discharge amount tends to accumulate inside the boosting compressor 54 having a small discharge amount. It is in. In the above configuration, the pressurizing compressor 54 is configured to be able to discharge the oil stored therein.

  Next, a configuration for discharging the oil stored in the boosting compressor 54 will be described.

  FIG. 4 is a schematic diagram showing the configuration of the boosting compressor 54 and peripheral devices connected to the boosting compressor 54. The pressurizing compressor 54 stores oil in a high pressure state inside the pressurizing compressor 54, and is a rotary compressor in the present embodiment. In this figure, the pressurizing compressor 54 includes a sealed container 81, and a motor 82 is housed in the upper side of the sealed container 81, and a compression element 83 that is rotationally driven by the motor 82 is housed in the lower side. The sealed container 81 is hermetically sealed by high frequency welding or the like after the motor 82 and the compression element 83 are accommodated in a previously divided part.

  The motor 82 includes a stator 84 fixed to the inner wall of the sealed container 81, and a rotor 85 that is supported inside the stator 84 so as to be rotatable about a rotation shaft 86. The stator 84 is provided with a stator winding 87 that applies a rotating magnetic field to the rotor 85.

  The compression element 83 includes a first rotary cylinder 89 and a second rotary cylinder 90 that are partitioned by an intermediate partition plate 88. Eccentric portions 91 and 92 that are rotationally driven by a rotating shaft 86 are attached to the cylinders 89 and 90, and the eccentric positions of the eccentric portions 91 and 92 are 180 degrees out of phase with each other.

  The first rotary cylinder 89 and the second rotary cylinder 90 include a first roller 93 and a second roller 94 that rotate in the cylinders 89 and 90. These rollers 93 and 94 rotate in the cylinders 89 and 90 by the rotation of the eccentric portions 91 and 92, respectively.

  Reference numerals 95 and 96 denote a first frame body and a second frame body, respectively. The first frame body 95 forms a compression space in which a cylinder 89 is closed between the intermediate partition plate 88 and the second frame body. Similarly, the frame 96 forms a compression space in which the cylinder 90 is closed with the intermediate partition plate 88. Each of the first frame body 95 and the second frame body 96 includes bearing portions 97 and 98 that rotatably support the lower portion of the rotation shaft 86. Further, discharge mufflers 99 and 100 are attached to the first frame body 95 and the second frame body 96 so as to cover the first frame body 95 and the second frame body 96. The discharge muffler 99 communicates with the cylinder 89 through a discharge hole (not shown) provided in the first frame 95. Similarly, the discharge muffler 100 is also provided in the second frame 96. The cylinder 90 communicates with a discharge hole (not shown). Reference numeral 101 denotes a bypass pipe provided outside the sealed container 81, and communicates with the inside of the discharge muffler 100.

  Further, a discharge pipe 102 for discharging the refrigerant compressed by the cylinders 89 and 90 is provided at the upper part of the sealed container 81, and the discharge pipe 102 is connected to the oil separator 45. Further, an oil discharge pipe 103 (oil discharge pipe) for discharging the oil stored in the closed container 81 (the pressurizing compressor 54) to the discharge side of the pressurizing compressor 54 is provided on the side surface of the sealed container 81. Route) is connected. The oil discharge pipe 103 is connected to a storage upper limit position of oil stored in the pressurizing compressor 54. The storage upper limit position refers to the oil in the pressurization compressor 54 in the storage upper limit position. Is stored, the position where it is assumed that the operation of the booster compressor 54 is hindered. In the present embodiment, the oil discharge pipe 103 is provided between the motor 82 and the compression element 83, and prevents the oil level stored in the sealed container 81 from reaching the motor 82. The oil discharge pipe 103 is connected to the discharge pipe 102 between the boosting compressor 54 and the oil separator 45. Therefore, when the oil level stored in the sealed container 81 rises to the oil storage upper limit position, the oil level is discharged to the discharge pipe 102 through the oil discharge pipe 103.

  In addition, suction pipes 104 and 105 for sucking low-pressure refrigerant evaporated by the freezing evaporator 49 are provided below the side surface of the sealed container 81, and the suction pipes 104 and 105 are respectively connected to a cylinder 89. , 90. The suction pipes 104 and 105 are provided with a thin tube (capillary tube) 106 for supplying oil stored in the oil separator 45 to the pressurizing compressor 54. In addition, a sealed terminal 107 for supplying electric power from the outside of the sealed container 81 to the stator winding 87 of the stator 84 is provided on the upper part of the sealed container 81. The lead wire connecting the sealed terminal 107 and the stator winding 87 is not shown.

  Next, the operation of discharging the oil stored in the boosting compressor 54 will be described.

  The refrigerant evaporated in the freezing evaporator 49 is introduced into the first rotary cylinder 89 and the second rotary cylinder 90 through the suction pipes 104 and 105 of the pressurizing compressor 54, and the cylinders 89, The first roller 93 and the second roller 94 rotate in the inside 90 and are compressed. The compressed refrigerant is discharged into the sealed container 81 through the discharge mufflers 99 and 100 and the bypass pipe 101, and the inside of the sealed container 81 is in a high pressure state.

  The refrigerant released into the sealed container 81 reaches the discharge pipe 102 through the gap between the stator windings 87 provided in the sealed container 81 and flows into the oil separator 45 through the discharge pipe 102. In this case, the stator winding 87 is cooled as the discharged refrigerant passes through the gap between the stator windings 87.

  In this case, part of the oil that has flowed into the boosting compressor 54 flows out through the discharge pipe 102, but the refrigerant discharge amount of the boosting compressor 54 is smaller than the discharge amount of the cooling compressor 37. The amount of oil mixed with the refrigerant and flowing out of the pressurizing compressor 54 is small. Therefore, the oil flowing into the boosting compressor 54 is stored in the boosting compressor 54.

  When the oil level in the sealed container 81 does not reach the position of the oil discharge pipe 103, the refrigerant released into the sealed container 81 flows out to the oil separator 45 through the discharge pipe 102 and the oil discharge pipe 103. . In this case, if the amount of refrigerant passing through the stator winding 87 is insufficient, the stator winding 87 becomes poorly cooled, so that the diameters of the discharge pipe 102 and the oil discharge pipe 103 are sufficient to cool the stator winding 87. It has been adjusted so that it can.

  When the oil level in the sealed container 81 reaches the position of the oil discharge pipe 103, the oil is discharged from the sealed container 81 through the oil discharge pipe 103 together with the refrigerant, and joins the discharge pipe 102 to the oil separator 45. Sent to. In this case, the pressure of the refrigerant flowing through the discharge pipe 102 is slightly reduced due to the pressure loss when the refrigerant passes through the gap between the stator windings 87. For this reason, the pressure in the sealed container 81 is higher by the amount of pressure loss, and by utilizing the pressure difference between the refrigerant pressure in the sealed container 81 and the refrigerant pressure flowing through the discharge pipe 102, the pressure in the sealed container 81 is increased. It is possible to discharge the oil stored in the oil separator 45 to the oil separator 45 located on the discharge side of the pressurizing compressor 54.

  The oil stored in the oil separator 45 is returned to the suction pipes 104 and 105 of the pressurizing compressor 54 through the capillary tube 106.

  In general, since a compressor with a large refrigerant discharge amount has a larger amount of oil discharged to the outside than a compressor with a small refrigerant amount, in this embodiment, an oil discharge pipe is connected to the booster compressor 54 with a small refrigerant discharge amount. However, if the compressor with a small refrigerant discharge amount has a larger oil discharge amount, an oil discharge pipe is provided in the compressor with a small oil discharge amount.

  According to the present embodiment, the cooling compressor 37 and the booster compressor 54 with a smaller refrigerant discharge amount than the cooling compressor 37 are connected in series, and the oil discharge pipe 103 is connected to the booster compressor 54. The oil stored in the high-pressure compressor 54 can be discharged through the oil discharge pipe 103, and the oil discharged from the cooling compressor 37 having a large refrigerant discharge amount can be discharged. It is possible to prevent the pressure boosting compressor 54 having a small amount from being accumulated in a biased manner.

  Further, since the oil discharge pipe 103 is provided at the oil storage upper limit position of the pressurizing compressor 54, the oil is prevented from being accumulated in the pressurizing compressor 54 beyond the storage upper limit position. Further, since the oil discharge pipe 103 is connected between the motor 82 and the compression element 83, it is prevented that the operation of the boosting compressor 54 is hindered by contact of the motor 82 with oil. it can.

  Further, by providing the outdoor unit 12 with the cooling compressor 37 and the booster unit 22 with the boosting compressor 54 and the oil discharge pipe 103, each of these compressors 37, 54 as in the prior art. Without being connected by an oil equalizing pipe, it is possible to prevent oil from being accumulated in the pressure-increasing compressor 54 with a small refrigerant discharge amount.

  As mentioned above, although this invention was demonstrated based on one Embodiment, this invention is not limited to this. For example. In the present embodiment, the case where the present invention is applied to a refrigeration system applied to a store such as a convenience store has been described. However, a refrigeration system that performs air conditioning and cooling of equipment to be cooled other than the refrigeration case 3 and the refrigeration case 4. Can be widely applied to. Furthermore, the piping configuration shown in the above embodiment is not limited thereto, and can be appropriately changed without departing from the gist of the present invention.

  Moreover, although this embodiment demonstrated the structure which connected the 1st compressor and the 2nd compressor in series, not only this but a 1st compressor and a 2nd compressor are paralleled. The present invention can also be applied when connected. For example, in the air conditioning system 6, among the air-conditioning compressors 13 </ b> A and 13 </ b> B connected in parallel, an oil discharge pipe is provided in a compressor with a small refrigerant discharge amount so that a compressor with a large refrigerant discharge amount It is possible to prevent oil from being biased and accumulated inside the compressor with a small discharge amount.

  In this embodiment, the diameters of the discharge pipe 102 and the oil discharge pipe 103 are adjusted so that the motor 82 of the boosting compressor 54 can be sufficiently cooled. However, the oil discharge pipe 103 is provided with an electric valve or the like. Thus, when the amount of oil in the pressurizing compressor 54 exceeds a predetermined amount, the motor-operated valve may be opened to discharge the oil.

  Further, in the present embodiment, the booster compressor 54, which has a smaller refrigerant discharge amount than the cooling compressor 37, is provided with the oil discharge pipe 103. It is good also as a structure provided with an oil discharge pipe in a compressor.

It is a figure which shows the system configuration | structure containing the refrigerant circuit of the refrigerating system concerning embodiment of this invention. It is a perspective view which shows the external appearance of an outdoor unit. It is a top view in the state where an upper surface panel of an outdoor unit was removed. It is the schematic which showed the structure of the compressor for pressure | voltage rise, and the peripheral device connected to this pressure | voltage rise compressor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigeration system 3 Refrigeration case 4 Refrigeration case 6 Air conditioning system part 8 Cooling system part 11 Indoor unit 12 Outdoor unit 13A, 13B Air-conditioning compressor 21 Cascade heat exchanger 22 Booster unit 37 Cooling compressor (1st compressor)
54 Compressor for pressurization (second compressor)
81 Sealed container 82 Motor 83 Compression element 103 Oil discharge pipe (oil discharge path)

Claims (5)

A first compressor, a second compressor connected in series or in parallel to the first compressor, and having a smaller refrigerant discharge amount than the first compressor, and the second compression An oil separator connected to the refrigerant discharge side of the machine,
The second compressor has a configuration in which a motor is accommodated in the upper side of the hermetic container and a compression element is accommodated in the lower side, and oil stored in a high pressure state in the hermetic container is interposed between the compression element and the motor. An refrigeration system , wherein an oil discharge path for discharging to the oil separator is connected, and a thin tube is connected between the oil separator and the suction side of the second compressor .   The refrigeration system according to claim 1, wherein the oil discharge path is connected to a storage upper limit position of oil stored in the second compressor. A cooling system unit that cools the inside of a cooling storage facility including a refrigeration case and a refrigerated case is provided, and the cooling system unit includes a first compressor, a second compressor, and an oil discharge path. The refrigeration system according to claim 1 or 2 . The cooling system section includes an outdoor unit and a booster unit in addition to the refrigeration case and the refrigeration case, the outdoor unit is provided with a first compressor, and the booster unit is provided with a second compressor and an oil discharge path. The refrigeration system according to claim 3 . The first compressor is a cooling compressor whose main role is refrigerant circulation, and the second compressor is configured to increase the pressure of the refrigerant that has passed through the refrigeration case to the refrigerant pressure that has passed through the refrigeration case. The refrigeration system according to claim 3 or 4 , wherein the refrigeration system is a compressor for pressurization.

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