JP6662753B2 - Refrigeration equipment - Google Patents

Description

  The present invention relates to a refrigerator.

  BACKGROUND ART Conventionally, a refrigerating apparatus provided with an oil separator and an oil return pipe for a compressor has been proposed so that a refrigerating machine oil as a lubricant in the compressor is not depleted.

  For example, in the refrigerating apparatus described in Patent Literature 1 (Japanese Patent Application Laid-Open No. 2011-208860), an oil separator for separating refrigerating machine oil from refrigerant at a discharge side of a compressor is provided. An oil return circuit is provided for returning the refrigerating machine oil separated by the separator to an upstream side of a gas-liquid separator provided on the suction side of the compressor. An electronic expansion valve capable of controlling the throttle opening is provided in the oil return circuit. By controlling the opening of the electronic expansion valve in accordance with the rotation speed of the compressor and the pressure difference between the suction side and the discharge side of the compressor, an appropriate amount of refrigeration oil for the compressor is provided. It can be returned.

  However, in the refrigerating device described in Patent Document 1, only one compressor is provided, and when a plurality of compressors are connected in parallel with each other, supply of refrigerating machine oil to each compressor is performed as follows. Not considered at all.

  In particular, when a plurality of compressors are connected in parallel with each other and the amount of circulation of the refrigerant or the refrigerating machine oil is different in each compressor, the amount of the refrigerating machine oil is reduced in some of the compressors. There is a possibility that a large amount of refrigerating machine oil will be discharged due to an excessive amount, and the refrigerating machine oil may become depleted in some other compressors.

  The present invention has been made in view of the above-described points, and an object of the present invention is to provide a plurality of compressors which are connected in parallel with each other, to determine a difference in the amount of refrigerating machine oil between each compressor. An object of the present invention is to provide a refrigeration apparatus that can be kept small.

The refrigeration apparatus according to the first aspect includes a plurality of compressors, an oil separator, a refrigerant supply pipe, an oil return pipe, and a flow rate adjustment mechanism, and further includes a first control unit, Alternatively, it further includes a plurality of flow control valves and a second control unit. The plurality of compressors include at least one inverter compressor. The plurality of compressors are connected to each other in parallel. The oil separator is provided on the discharge side of the plurality of compressors. The refrigerant supply pipe supplies the refrigerant to the plurality of compressors. The oil return pipe connects the oil separator and the refrigerant supply pipe. The flow rate adjusting mechanism is a valve provided on the oil return pipe and capable of controlling the opening degree. The first control unit is configured to reduce the rotation speed of the inverter compressor when the first predetermined condition is satisfied in a situation where the rotation speed of the inverter compressor is higher than the rotation speeds of the compressors other than the inverter compressor. Performs a first flow rate control to return more refrigerating machine oil to a compressor other than the inverter compressor whose rotation speed has been reduced, and a flow rate adjustment mechanism after starting the first flow rate control mechanism before starting the first flow rate control. The flow rate adjusting mechanism is controlled so as to increase the flow rate at. The plurality of flow control valves are provided so as to correspond to flow paths for supplying the refrigerant to each of the plurality of compressors in the refrigerant supply pipe. The second control unit, when the rotation speed of the inverter compressor is higher than the rotation speed of the compressors other than the inverter compressor, the flow control valve provided to correspond to the inverter compressor, By changing the relative flow control degree of the flow control valve other than the flow control valve provided so as to satisfy the second predetermined condition, more compressors other than the inverter compressor are provided. The second flow rate control for returning the refrigerating machine oil is performed, and the flow rate adjustment mechanism is controlled so that the flow rate in the flow rate adjustment mechanism is increased after the second flow rate control is started before the second flow rate control is started.

  In addition, the refrigerant supply pipe may supply the refrigerant to each suction side of the plurality of compressors, or may supply the refrigerant at an intermediate stage of each compression process of the plurality of compressors.

  In addition, the first predetermined condition is not particularly limited, and the first predetermined condition is satisfied when the inverter compressor or a compressor other than the inverter compressor is continuously operated or integrated for a predetermined period. May be satisfied, or may be satisfied when a predetermined time of day comes, or when the amount of refrigerating machine oil in the compressors other than the inverter compressor is known by integration, it is determined. The condition may be satisfied when the amount is smaller than a predetermined amount.

  With respect to the refrigeration system including the first control unit, when the first predetermined condition is satisfied, the rotational speed of the inverter compressor is reduced to reduce the rotational speed of the compressor other than the inverter compressor. To perform a first flow rate control to return more refrigeration oil. As a result, it is possible to improve the situation where the refrigeration oil is insufficient in the compressors other than the inverter compressor, and to reduce the difference between the excess and deficiency in the amount of the refrigeration oil in each compressor.

  Regarding the refrigeration system including the plurality of flow control valves and the second control unit, the flow control valve provided to correspond to the inverter compressor and the flow control valve provided to correspond to the inverter compressor are other than the flow control valve. By changing the relative flow control degree between the flow control valve and the second flow control valve when the second predetermined condition is satisfied, the second flow control for returning more refrigerating machine oil to the compressors other than the inverter compressor is performed. Do. As a result, it is possible to improve the situation where the refrigeration oil is insufficient in the compressors other than the inverter compressor, and to reduce the difference between the excess and deficiency in the amount of the refrigeration oil in each compressor.

  A refrigeration apparatus according to a second aspect includes a plurality of compressors, an oil separator, a refrigerant supply pipe, an oil return pipe, and a first control unit. The plurality of compressors include at least one inverter compressor. The plurality of compressors are connected to each other in parallel. The oil separator is provided on the discharge side of the plurality of compressors. The refrigerant supply pipe supplies the refrigerant to the plurality of compressors. The oil return pipe connects the oil separator and the refrigerant supply pipe. When the first predetermined condition is satisfied, the first control unit reduces the rotation speed without stopping the inverter compressor, thereby increasing the number of compressors other than the inverter compressor whose rotation speed has been reduced. The first flow control for returning the refrigerating machine oil is performed. The plurality of compressors include a variable capacity compressor and a fixed capacity compressor.

  In addition, the refrigerant supply pipe may supply the refrigerant to each suction side of the plurality of compressors, or may supply the refrigerant at an intermediate stage of each compression process of the plurality of compressors.

  The first predetermined condition is not particularly limited, and the first predetermined condition is satisfied when the inverter compressor or a compressor other than the inverter compressor is continuously operated or integrated for a predetermined period of time. Or may be satisfied when a predetermined time of day has come, or when the amount of refrigerating machine oil in the compressors other than the inverter compressor is known by integration, it is determined. The condition may be satisfied when the amount is smaller than a predetermined amount.

  In this refrigeration apparatus, when the first predetermined condition is satisfied, the rotation speed of the inverter compressor is reduced, thereby returning more refrigeration oil to the compressors other than the inverter compressor whose rotation speed has been reduced. The first flow rate control is performed. As a result, it is possible to improve the situation where the refrigeration oil is insufficient in the compressors other than the inverter compressor, and to reduce the difference between the excess and deficiency in the amount of the refrigeration oil in each compressor.

  A refrigeration apparatus according to a third aspect is the refrigeration apparatus according to the second aspect, and further includes a flow rate adjusting mechanism. The flow rate adjusting mechanism is provided on the oil return pipe.

  The flow rate adjusting mechanism is not particularly limited, and may be, for example, an electric expansion valve or a capillary tube.

  In this refrigeration apparatus, since the flow rate adjusting mechanism is provided in the oil return pipe, it is possible to adjust the flow rate of the refrigeration oil returned to each compressor through the oil return pipe.

  A refrigeration apparatus according to a fourth aspect is the refrigeration apparatus according to the third aspect, wherein the flow rate adjustment mechanism is a valve that can control an opening degree. The first control unit controls the flow rate adjusting mechanism such that the flow rate in the flow rate adjusting mechanism increases after the first flow rate control is started before the first flow rate control is started.

  Note that increasing the flow rate in the flow rate adjusting mechanism includes, for example, increasing the valve opening of the electric expansion valve when the flow rate adjusting mechanism is configured by an electric expansion valve.

  In this refrigeration apparatus, when performing the first flow rate control for returning more refrigeration oil to the compressors other than the inverter compressor, the amount of the refrigeration oil passing through the flow rate adjusting mechanism increases. Thereby, the amount of refrigerating machine oil flowing through the oil return pipe and the refrigerant supply pipe increases. Therefore, it becomes possible to return the refrigerating machine oil to compressors other than the inverter compressor more efficiently.

  The refrigeration apparatus according to a fifth aspect is the refrigeration apparatus according to any of the second to fourth aspects, further comprising a heat source side heat exchanger, an intermediate expansion valve, and a plurality of flow rate control valves. I have. The heat source side heat exchanger condenses the refrigerant discharged from the compressor. The refrigerant supply pipe is an injection pipe provided to branch a part of the refrigerant that has passed through the heat source side heat exchanger and to join the refrigerant in the middle of each compression step of the plurality of compressors. The intermediate expansion valve is provided in the middle of the injection pipe. The plurality of flow control valves are provided on the plurality of compressor sides of the injection pipe relative to the intermediate expansion valve so as to correspond to each of the plurality of compressors.

  In this refrigerating apparatus, the oil return pipe can guide the refrigerating machine oil or the like separated by the oil separator to the middle of the compression process of the compressor via the injection pipe. In this way, a part of the high-temperature fluid discharged from the compressor toward the oil separator is guided not in the suction side of the compressor but in the middle of the compression process in the compressor. It is possible to suppress that part of the heat energy of the discharged high-temperature fluid is used to raise the temperature of the suction refrigerant of the compressor.

  In the refrigeration apparatus according to the first aspect, it is possible to reduce the difference between the excess and deficiency of the amount of refrigerating machine oil in each compressor, and to adjust the flow rate of the refrigerating machine oil returned to each compressor through the oil return pipe. Refrigeration oil can be more efficiently returned to compressors other than the inverter compressor.

  In the refrigeration apparatus according to the second aspect, it is possible to reduce the difference between the excess and deficiency of the amount of refrigerating machine oil in each compressor.

  In the refrigeration apparatus according to the third aspect, it is possible to adjust the flow rate of refrigeration oil returned to each compressor through the oil return pipe.

  In the refrigeration apparatus according to the fourth aspect, it becomes possible to more efficiently return the refrigeration oil to the compressors other than the inverter compressor.

  In the refrigeration apparatus according to the fifth aspect, it is possible to suppress that part of the heat energy of the high-temperature fluid discharged from the compressor is used to increase the temperature of the refrigerant sucked into the compressor. .

1 is an overall configuration diagram of a refrigeration apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram schematically showing a schematic configuration of a controller and each unit connected to the controller. When executing the load processing control of the compressor and the compressor oil leveling control, the oil return control of the oil return valve and the oil leveling control, and the normal oil distribution control and the oil leveling oil distribution control of the first to third injection valves. 5 is a flowchart showing an example of the flow of processing of the controller in FIG. The whole block diagram of the refrigerating device which has the refrigerant circuit which concerns on modification B. The whole block diagram of the refrigerating device which has the refrigerant circuit concerning modification C. The whole block diagram of the refrigerating device which has the refrigerant circuit which concerns on modification D. The whole block diagram of the refrigerating device which has the refrigerant circuit which concerns on modification E.

  Hereinafter, a refrigeration apparatus 100 according to an embodiment of the present invention will be described with reference to the drawings. The following embodiments are specific examples of the present invention, and do not limit the technical scope of the present invention, and can be appropriately modified without departing from the gist of the invention.

(1) Refrigeration device 100
FIG. 1 is a schematic configuration diagram of a refrigeration apparatus 100 according to one embodiment of the present invention. The refrigeration apparatus 100 is an apparatus that cools a use-side space such as a refrigerator or a showcase of a store by a vapor compression refrigeration cycle.

  The refrigeration apparatus 100 mainly includes the heat source unit 2, a plurality of (here, two) use units (first use unit 50, second use unit 60), heat source unit 2, first use unit 50, and second use unit. The liquid-side refrigerant communication pipe 6 and the gas-side refrigerant communication pipe 7 connecting the unit 60, a plurality of remote controllers (first remote controller 50a, second remote controller 60a) as input devices and display devices, and operation of the refrigeration system 100 And a controller 70 for controlling.

  In the refrigeration apparatus 100, the first usage unit 50 and the second usage unit 60 are connected in parallel to one heat source unit 2 via the liquid-side refrigerant communication pipe 6 and the gas-side refrigerant communication pipe 7. Thus, the refrigerant circuit 10 is configured. In the refrigeration apparatus 100, a refrigeration cycle is performed in which the refrigerant sealed in the refrigerant circuit 10 is compressed, cooled or condensed, decompressed, heated or evaporated, and then compressed again. Note that, although not particularly limited, in the present embodiment, the refrigerant circuit 10 is filled with R32 as a refrigerant for performing a vapor compression refrigeration cycle.

(1-1) Heat source unit 2
In the heat source unit 2, the first usage unit 50 and the second usage unit 60 are connected in parallel via the liquid-side refrigerant communication pipe 6 and the gas-side refrigerant communication pipe 7, and constitute a part of the refrigerant circuit 10. I have. The heat source unit 2 mainly includes a compressor 21, an oil separator 23, a four-way switching valve 24, a heat source side heat exchanger 25, a heat source side fan 45, a receiver 27, a subcooler 31, a heat source side Expansion valve 28, injection pipe 30, supercooled expansion valve 32, injection valve 33, oil return pipe 38, oil return valve 39, first branch pipe 34, second branch pipe 36, liquid side It has a closing valve 48 and a gas-side closing valve 49.

  Further, the heat source unit 2 is connected to one of the connection ports of the four-way switching valve 24 from the discharge side of the compressor 21 and has a discharge-side pipe 41 provided with an oil separator 23 in the middle thereof, A suction-side pipe 42 connecting the four-way switching valve 24 to one of the connection ports from the suction side of the four-way switching valve 24; a first heat-source liquid-side pipe 43 connecting the liquid side of the heat-source-side heat exchanger 25 to the receiver 27; 27 has a second heat source liquid side pipe 44 connecting the end of the heat source side heat exchanger 25 opposite to the liquid side shut-off valve 48.

  The compressor 21 is a device that compresses a low-pressure refrigerant in a refrigeration cycle to a high pressure. Although not particularly limited, the compressor 21 of the present embodiment includes a first compressor 21a, a second compressor 21b, and a third compressor 21c connected in parallel with each other. In the present embodiment, the first compressor 21a, the second compressor 21b, and the third compressor 21c are all hermetic high-pressure dome-type scroll compressors. Among them, the first compressor 21a (inverter compressor) is a compressor having a variable capacity (variable rotation speed), and is provided with an inverter. The second compressor 21b (compressor other than the inverter compressor) and the third compressor 21c (compressor other than the inverter compressor) are fixed-capacity (fixed-speed) compressors, and are provided with an inverter. Absent. The maximum rotation speed of the first compressor 21a is configured to be higher than the fixed rotation speeds of the second compressor 21b and the third compressor 21c.

  Individual suction pipes are connected to respective suction sides of the first compressor 21a, the second compressor 21b, and the third compressor 21c. These individual suction pipes are united on the most upstream side. A set of these individual suction pipes on the most upstream side and the four-way switching valve 24 are connected by a suction pipe 42.

  An individual discharge pipe is connected to each discharge side of the first compressor 21a, the second compressor 21b, and the third compressor 21c. These individual discharge tubes are united at the most downstream side. A group at the most downstream side of these individual discharge pipes and the four-way switching valve 24 are connected by a discharge side pipe 41. A check valve 22a that allows only the discharge flow is provided on the discharge side of the first compressor 21a. Similarly, a check valve 22b that allows only the discharge flow is provided on the discharge side of the second compressor 21b, and a check valve that allows only the discharge flow also on the discharge side of the third compressor 21c. A valve 22c is provided.

  The oil separator 23 is a container for mainly separating refrigerating machine oil from the refrigerant discharged from the compressor 21, and is provided in the middle of the discharge-side pipe 41. The oil separator 23 receives the fluid (including the refrigerant and the refrigerating machine oil) discharged from the first compressor 21a, the second compressor 21b, and the third compressor 21c, which are a plurality of compressors included in the compressor 21. They are made to flow together and mainly separate the refrigerating machine oil (note that some gas refrigerant may be mixed depending on the operating conditions). For this reason, for example, compared with an oil separator provided so as to correspond one-to-one with the respective discharge sides of the first compressor 21a, the second compressor 21b, and the third compressor 21c, the present embodiment is different from the first embodiment. The oil separator 23 has a large capacity.

  An oil return pipe 38 extends from the oil separator 23 provided in the middle of the discharge side pipe 41 so as to branch off. The other end of the oil return pipe 38 is in the middle of an injection pipe 30 described later, and is connected between the supercooler 31 and the first to third injection branch pipes 33x, 33y, 33z. Further, an oil return valve 39 constituted by an electronic expansion valve capable of controlling the valve opening is provided in the middle of the oil return pipe 38.

  The four-way switching valve 24 is connected to a downstream end of the discharge-side pipe 41. By switching the connection state of the four-way switching valve 24, the discharge side of the compressor 21 and the heat source side heat exchanger 25 are connected, and the gas side closing valve 49 and the suction side of the compressor 21 are connected. A cooling operation state (a state of normal operation) and a heating operation state in which the discharge side of the compressor 21 and the gas side shut-off valve 49 are connected and the heat source side heat exchanger 25 and the suction side of the compressor 21 are connected ( (The state of defrost operation).

  The heat source side heat exchanger 25 is a heat exchanger that functions as a radiator for a high-pressure refrigerant in the refrigeration cycle and as an evaporator for a low-pressure refrigerant. One end of the heat source side heat exchanger 25 is connected to the refrigerant pipe extending from the four-way switching valve 24 side, and the other end is connected to the first heat source liquid side pipe 43.

  The heat source side fan 45 takes in the outside air (heat source side air) into the heat source unit 2, causes the heat source side heat exchanger 25 to exchange heat with the refrigerant, and then forms an air flow for discharging the air to the outside. The heat source side fan 45 is driven to rotate by a heat source side fan motor M45. The air volume of the heat source side fan 45 is controlled by adjusting the rotation speed of the heat source side fan motor M45.

  In the middle of the first heat source liquid side pipe 43, a first heat source liquid side check valve 26 that allows only the refrigerant flow from the heat source side heat exchanger 25 side to the receiver 27 side is provided.

  The receiver 27 is a container for temporarily storing the refrigerant, and is provided on the first heat source liquid side pipe 43 on the side opposite to the heat source side heat exchanger 25 side. Here, the first heat source liquid side pipe 43 is connected to a gas phase portion above the receiver 27.

  The heat source side expansion valve 28 is configured by an electric expansion valve capable of controlling the valve opening, and is disposed in the second heat source liquid side pipe 44 (more specifically, at a downstream portion of the subcooler 31). I have.

  The supercooler 31 is a heat exchanger that further cools the refrigerant temporarily stored in the receiver 27 before sending the refrigerant to the first and second usage units 50 and 60, and the receiver 27 of the second heat source liquid side pipe 44. And the heat source side expansion valve 28.

  The injection pipe 30 extends so as to branch from the subcooler 31 of the second heat source liquid side pipe 44 and the heat source side expansion valve 28, and is connected in the middle of the compression process of the compressor 21.

  The supercooling expansion valve 32 is configured by an electric expansion valve capable of controlling the valve opening, and is provided in the injection pipe 30 at a position upstream of the supercooler 31. In the subcooler 31, heat exchange between the refrigerant flowing through the second heat source liquid side pipe 44 flowing out of the receiver 27 and the refrigerant flowing through the injection pipe 30 and reduced in pressure by the supercooling expansion valve 32 is performed. Done. As a result, the refrigerant flowing through the second heat source liquid side pipe 44 is supercooled and flows toward the heat source side expansion valve 28. On the other hand, the refrigerant that has passed through the subcooler 31 in the injection pipe 30 flows further downstream of the injection pipe 30.

  The downstream side (compressor 21 side) of the injection pipe 30 from the junction with the oil return pipe 38 extends to the compressor 21 via the first to third injection branch pipes 33x, 33y, and 33z. More specifically, the first injection branch which flows so as to merge in the middle of the compression process of the first compressor 21a is further downstream (compressor 21 side) of the part of the injection pipe 30 that merges with the oil return pipe 38. A pipe 33x, a second injection branch pipe 33y that flows so as to merge in the middle of the compression step of the second compressor 21b, and a third injection branch pipe 33z that flows so as to merge in the middle of the compression step of the third compressor 21c. And branching into.

  The injection valve 33 is configured by an electric expansion valve whose valve opening can be controlled, and is provided in the injection pipe 30 in the first to third injection branch pipes 33x, 33y, and 33z, respectively. Specifically, a first injection valve 33a is provided in the middle of the first injection branch pipe 33x, a second injection valve 33b is provided in the middle of the second injection branch pipe 33y, and a third injection branch pipe 33z is provided. A third injection valve 33c is provided on the way.

  The second heat source liquid side pipe 44 has a second heat source between the heat source side expansion valve 28 and the liquid side closing valve 48 that allows only the refrigerant flow from the heat source side expansion valve 28 to the liquid side closing valve 48. A liquid-side check valve 29 is provided.

  The first branch pipe 34 is located in the middle of the second heat source liquid side pipe 44 and branches from between the second heat source liquid side check valve 29 and the liquid side closing valve 48. It is a refrigerant pipe provided on the way so as to join a portion between the first heat source liquid side check valve 26 and the receiver 27. In the middle of the first branch pipe 34, there is provided a first branch check valve 35 that allows only the refrigerant flow from the second heat source liquid side pipe 44 to the first heat source liquid side pipe 43.

  The second branch pipe 36 is located in the middle of the second heat source liquid side pipe 44 and branches from between the heat source side expansion valve 28 and the second heat source liquid side check valve 29. This is a refrigerant pipe provided on the way to join a portion between the heat source side heat exchanger 25 and the first heat source liquid side check valve 26. In the middle of the second branch pipe 36, there is provided a second branch check valve 37 that allows only the refrigerant flow from the second heat source liquid side pipe 44 to the first heat source liquid side pipe 43.

  The liquid-side shut-off valve 48 is a manual valve disposed at a connection portion between the second heat source liquid-side pipe 44 and the liquid-side refrigerant communication pipe 6.

  The gas-side shut-off valve 49 is a manual valve disposed at a connection portion between a pipe extending from the four-way switching valve 24 and the gas-side refrigerant communication pipe 7.

  Various sensors are arranged in the heat source unit 2. Specifically, the suction-side pipe 42 is provided with a low-pressure sensor 40a that detects a suction pressure that is a pressure of the refrigerant on a suction side of the compressor 21. In the middle of the individual discharge pipe of the first compressor 21a, a high-pressure sensor 40c that detects a discharge pressure that is a pressure of the refrigerant on a discharge side of the compressor 21 is provided. Further, an intermediate pressure sensor 40b for detecting an intermediate pressure in the refrigeration cycle is provided in the middle of the injection pipe 30 and between the junction of the injection pipe 30 and the oil return pipe 38 and the supercooler 31. Have been. Further, a heat source side air temperature sensor 46 that detects the temperature of the heat source side air sucked into the heat source unit 2 is arranged around the heat source side heat exchanger 25 or the heat source side fan 45. Then, a discharge temperature sensor 47 for detecting the temperature of the refrigerant discharged from the compressor 21 is provided in the middle of the discharge-side pipe 41 (in the present embodiment, on the upstream side of the oil separator 23 and the first compressor 21a At the position after the refrigerant discharged from the second compressor 21b and the third compressor 21c have joined).

  The heat source unit 2 has a heat source unit control unit 20 that controls the operation of each unit constituting the heat source unit 2. The heat source unit control unit 20 has a microcomputer including a CPU, a memory, and the like. The heat source unit control unit 20 is connected to the use unit control unit 57 of each use unit 50 via a communication line, and transmits and receives control signals and the like.

(1-2) First Usage Unit 50
The first usage unit 50 is connected to the heat source unit 2 via the liquid-side refrigerant communication pipe 6 and the gas-side refrigerant communication pipe 7, and forms a part of the refrigerant circuit 10.

  The first usage unit 50 has a first usage-side expansion valve 54 and a first usage-side heat exchanger 52. The first usage unit 50 includes a first usage-side liquid refrigerant pipe 59 that connects the liquid-side end of the first usage-side heat exchanger 52 and the liquid-side refrigerant communication pipe 6, and a first usage-side heat exchanger 52. And a first usage-side gas refrigerant pipe 58 that connects the gas-side end of the gas-liquid refrigerant to the gas-side refrigerant communication pipe 7.

  The first usage-side expansion valve 54 is configured by an electric expansion valve capable of controlling the valve opening, and is provided in the middle of the first usage-side liquid refrigerant pipe 59.

  The first use-side heat exchanger 52 functions as a low-pressure refrigerant evaporator during the cooling operation in the refrigeration cycle to cool the internal air (use-side air), and as a refrigerant radiator during a heating operation such as a defrost operation. A functioning heat exchanger.

  Here, the first usage unit 50 sucks the usage-side air into the first usage unit 50, exchanges heat with the refrigerant in the first usage-side heat exchanger 52, and supplies the air to the usage-side space. It has a first use side fan 53. The first use side fan 53 is a fan for supplying the use side air as a heating source of the refrigerant flowing through the first use side heat exchanger 52 to the first use side heat exchanger 52. The first usage-side fan 53 is driven to rotate by a first usage-side fan motor M53.

  Further, the first usage unit 50 has a first usage unit control unit 57 that controls the operation of each unit constituting the first usage unit 50. The first usage unit control unit 57 has a microcomputer including a CPU, a memory, and the like. The first usage unit control unit 57 is connected to the heat source unit control unit 20 via a communication line, and transmits and receives control signals and the like.

(1-3) Second usage unit 60
The second usage unit 60 has the same configuration as the first usage unit 50, and is connected to the heat source unit 2 via the liquid-side refrigerant communication pipe 6 and the gas-side refrigerant communication pipe 7, and a part of the refrigerant circuit 10. Is composed. The second usage unit 60 is connected to the first usage unit 50 in parallel.

  The second usage unit 60 has a second usage-side expansion valve 64 and a second usage-side heat exchanger 62. The second usage unit 60 includes a second usage-side liquid refrigerant pipe 69 that connects the liquid-side end of the second usage-side heat exchanger 62 and the liquid-side refrigerant communication pipe 6, and a second usage-side heat exchanger 62. And a second usage-side gas refrigerant pipe 68 that connects the gas-side end of the gas-liquid refrigerant to the gas-side refrigerant communication pipe 7.

  The second usage-side expansion valve 64 is configured by an electric expansion valve that can control the valve opening, and is provided in the middle of the second usage-side liquid refrigerant pipe 69.

  The second use-side heat exchanger 62 functions as a low-pressure refrigerant evaporator during the cooling operation in the refrigeration cycle to cool the internal air (use-side air), and as a refrigerant radiator during a heating operation such as a defrost operation. A functioning heat exchanger.

  Here, similarly to the first usage unit 50, the second usage unit 60 also has a second usage-side fan 63 driven to rotate by a second usage-side fan motor M63.

  In addition, the second usage unit 60 has a second usage unit control unit 67 that controls the operation of each unit constituting the second usage unit 60. The second usage unit control unit 67 has a microcomputer including a CPU, a memory, and the like. The second usage unit control unit 67 is connected to the heat source unit control unit 20 via a communication line, and transmits and receives control signals and the like.

(1-4) First remote controller 50a, second remote controller 60a
The first remote controller 50a is an input device for the user of the first usage unit 50 to input various instructions for switching the operation state of the refrigeration apparatus 100. In addition, the first remote controller 50a also functions as a display device for displaying the operating state of the refrigeration apparatus 100 and predetermined notification information. The first remote controller 50a is connected to the first usage unit control unit 57 via a communication line, and mutually transmits and receives signals.

  The second remote controller 60a is also the same as the first remote controller 50a, and is an input device and a display device for the user of the second usage unit 60 to input various instructions for switching the operation state of the refrigeration apparatus 100. The second remote controller 60a is connected to the second usage unit control unit 67 via a communication line, and mutually transmits and receives signals.

(2) Details of Controller 70 In the refrigeration apparatus 100, the heat source unit control unit 20, the first usage unit control unit 57, and the second usage unit control unit 67 are connected via a communication line, so that the refrigeration system A controller 70 that controls the operation of the controller 100 is configured.

  FIG. 2 is a block diagram schematically showing a schematic configuration of the controller 70 and each unit connected to the controller 70.

  The controller 70 has a plurality of control modes, and controls the operation of the refrigeration apparatus 100 according to the control mode that is being changed. For example, the controller 70 has, as control modes, a cooling operation mode performed in normal times and a heating operation mode performed in reverse cycle defrost. The controller 70 performs oil return control and oil leveling control on the oil return valve 39 in both the cooling operation mode and the heating operation mode. The oil return control of the oil return valve 39 is a control for returning an appropriate amount of refrigerating machine oil to the first compressor 21a, the second compressor 21b, and the third compressor 21c according to the operation state of the refrigeration cycle. It is. The oil equalization control of the oil return valve 39 is performed by adjusting the valve opening of the oil return valve 39 to eliminate the shortage of refrigeration oil in the second compressor 21b and the third compressor 21c. This is control to make it larger than the opening.

  The controller 70 controls each actuator (specifically, the compressor 21, the four-way switching valve 24, the heat source side expansion valve 28, the supercooling expansion valve 32, the injection valve 33, the oil return valve 39, and the The heat source side fan 45 (heat source side fan motor M45) is electrically connected to various sensors (low pressure sensor 40a, intermediate pressure sensor 40b, high pressure sensor 40c, heat source side air temperature sensor 46, discharge temperature sensor 47, etc.). Have been. Further, the controller 70 is electrically connected to an actuator (specifically, the first usage-side fan 53 (first usage-side fan motor M53) and the first usage-side expansion valve 54) included in the first usage unit 50. Have been. Further, the controller 70 is electrically connected to an actuator (specifically, a second usage-side fan 63 (second usage-side fan motor M63), a second usage-side expansion valve 64) included in the second usage unit 60. Have been. Further, the controller 70 is electrically connected to the first remote controller 50a and the second remote controller 60a.

  The controller 70 mainly includes a storage unit 71, a communication unit 72, a mode control unit 73, an actuator control unit 74, and a display control unit 75. These units in the controller 70 are realized by the units included in the heat source unit control unit 20 and / or the use unit control unit 57 functioning integrally.

(2-1) Storage Unit 71
The storage unit 71 includes, for example, a ROM, a RAM, and a flash memory, and includes a volatile storage area and a nonvolatile storage area. The storage unit 71 stores a control program that defines processing in each unit of the controller 70. In addition, the storage unit 71 stores predetermined information (for example, a detection value of each sensor, a command input to the first remote controller 50a, the second remote controller 60a, and the like) in a predetermined storage area by each unit of the controller 70 as appropriate. Is done.

(2-2) Communication unit 72
The communication unit 72 is a functional unit that functions as a communication interface for transmitting and receiving signals to and from each device connected to the controller 70. The communication section 72 receives a request from the actuator control section 74 and transmits a predetermined signal to the designated actuator. The communication unit 72 receives signals output from various sensors, the first remote controller 50a, and the second remote controller 60a, and stores the signals in a predetermined storage area of the storage unit 71.

(2-3) Mode control unit 73
The mode control unit 73 is a functional unit that performs control mode switching and the like. The mode control unit 73 sets the cooling operation mode when the operation is performed in a state where the predetermined defrost condition regarding the adhesion of frost in the first and second usage-side heat exchangers 52 and 62 is not satisfied. Further, in the cooling operation mode, when the predetermined defrost condition is satisfied, the mode control unit 73 switches to the heating operation mode. Further, the mode control unit 73 performs the oil return control and the oil leveling control on the oil return valve 39 in both the cooling operation mode and the heating operation mode.

(2-4) Actuator control unit 74
The actuator control unit 74 controls the operation of each actuator (for example, the compressor 21 or the like) included in the refrigeration apparatus 100 according to the situation according to the control program.

  The actuator control unit 74 sets the connection state of the four-way switching valve 24 such that the discharge side of the compressor 21 and the heat source side heat exchanger 25 are connected, and the gas side closing valve 49 is connected to the suction side of the compressor 21. As the state, while controlling the heat source side expansion valve 28 to be in a fully open state, the rotation speed of the compressor 21, the heat source side fan 45, The opening degree, the opening degree of the oil return valve 39, the opening degrees of the first to third injection valves 33a, 33b, 33c, the opening degrees of the use side expansion valves 54, 64, the rotation speeds of the use side fans 53, 63, and the like. Control in real time. During execution of the cooling operation mode, the first to third injection valves 33a, 33b, 33c are all controlled to a state other than the fully closed state.

  In the heating operation mode, the actuator control unit 74 sets the connection state of the four-way switching valve 24 to the discharge side of the compressor 21 and the gas-side closing valve 49 so that the heat source side heat exchanger 25 and the compressor 21 With the suction side connected, the supercooling expansion valve 32 is controlled to be in a fully closed state, the use side expansion valves 54 and 64 are controlled to be in a fully open state, and the use side fans 53 and 63 are controlled. While controlling to stop, the rotation speed of the compressor 21, the opening degree of the heat source side fan 45, the opening degree of the heat source side expansion valve 28, the opening degree of the oil return valve 39, the first to The respective valve openings of the third injection valves 33a, 33b, 33c are controlled in real time. Note that, even during the execution of the heating operation mode, the first to third injection valves 33a, 33b, 33c are all controlled to a state other than the fully closed state.

  Here, in the cooling operation mode, load processing control and compressor leveling control are selectively executed for the compressor 21.

  In the cooling operation mode, oil return control and oil leveling control are selectively executed for the oil return valve 39.

  Furthermore, in the cooling operation mode, the normal oil distribution control and the oil distribution control during oil leveling are selectively executed for the first to third injection valves 33a, 33b, and 33c.

(2-4-1) Load Processing Control of Compressor 21 In load processing control of the compressor 21 (control other than when the compressor leveling control is executed in the cooling operation mode), the first usage unit 50 and the second usage unit The actuator control unit 74 performs capacity control according to the load so that the load required by the use unit 60 can be processed. Specifically, the target value of the suction pressure is set according to the cooling load required by the first usage unit 50 and the second usage unit 60, and the operating speed of the compressor 21 is set so that the suction pressure becomes the target value. Is controlled.

  Here, the actuator control unit 74 drives only the first compressor 21a at the time of start-up or when the load is small. When the refrigeration cycle becomes stable after start-up or when the load increases, the second compressor The control is performed such that the second compressor 21b and the third compressor 21c are also driven. In addition, the rotation speed of the variable displacement first compressor 21a having an inverter is driven to be higher than the rotation speed of the fixed rotation speed type second compressor 21b or the third compressor 21c.

(2-4-2) Compressor oil leveling control of the compressor 21 In the compressor oil leveling control of the compressor 21, the second compression is performed while the rotation speed of the first compressor 21a of the compressor 21 is set to a low rotation speed. The actuator control unit 74 performs control such that the operating states of the compressor 21b and the third compressor 21c are maintained (operated with a fixed rotation speed).

  Specifically, the actuator control unit 74 forcibly controls the rotation speed of the first compressor 21a to be equal to or less than a predetermined oil equalization rotation speed. Here, the rotation speed for oil equalization is not particularly limited. For example, the rotation speed for oil equalization can be set in advance as a rotation speed lower than the fixed rotation speed of the second compressor 21b or the third compressor 21c. When the rotation speed of the first compressor 21a immediately before the start of the oil control is set as a reference, the rotation speed may be lower than the reference.

(2-4-3) Oil Return Control of Oil Return Valve 39 In oil return control of the oil return valve 39 (control other than when the oil leveling control is performed in the cooling operation mode), oil from the compressor 21 is used. The actuator control unit 74 controls the opening degree to achieve the same amount of passing circulation as the rising amount. That is, the actuator control unit 74 controls the valve opening of the oil return valve 39 such that the “amount of oil rising from the compressor 21” is equal to the “circulation amount of the oil return valve 39”.

  Here, there is a relationship of “the amount of oil rise in the compressor” = “the amount of refrigerant circulated in the compressor” × “the oil rise rate of the compressor”. Here, when a plurality of compressors (the first compressor 21a, the second compressor 21b, and the third compressor 21c) constituting the compressor 21 are being driven, “each of the driven compressors is“ The “refrigerating amount of the compressor 21” is calculated by using the “refrigerating amount of the compressor” and the “oil rising rate of the compressor”, and the sum thereof is calculated. be able to.

The `` circulation amount of the compressor '' is not particularly limited, but may be calculated based on, for example, a piston displacement amount of the compressor, a driving speed of the compressor, a suction refrigerant density of the compressor,
The calculation may be made by dividing the input power of the compressor 21 by the enthalpy difference between the outlet and the inlet of the compressor 21.

  In addition, the above-mentioned "oil rising rate of the compressor" includes the driving speed of the compressor, the high pressure, the intermediate pressure, and the low pressure in the refrigeration cycle, and the degree of superheat of the refrigerant sucked by the compressor as necessary. Based on this, it can be calculated for each driven compressor.

  The “passage circulation amount in the oil return valve 39” is stored in the storage unit 71 in advance by storing the valve opening degree of the oil return valve 39, the difference between the refrigerant pressures before and after the oil return valve 39 (high pressure-intermediate pressure). It can be calculated by using the stored predetermined relation value table data. Here, the predetermined relation value table data indicates that the larger the valve opening degree of the oil return valve 39 is, the larger the passing circulation amount is, and the larger the difference between the refrigerant pressures before and after the oil return valve 39 is, the larger the passing circulation amount is. This is data obtained in advance based on the relationship.

  As described above, the valve opening degree of the oil return valve 39 is substantially equal to “the oil rising amount of the compressor 21” and “the difference between the refrigerant pressure before and after the oil return valve 39 (high pressure-intermediate pressure)”. , The opening degree is controlled in accordance with.

(2-4-4) Oil leveling control of oil return valve 39 In oil leveling control of oil return valve 39, actuator control unit 74 controls oil return valve 39 in the cooling operation mode performed immediately before. The opening of the oil return valve 39 is opened so that the valve opening is controlled to be even larger than the valve opening controlled by the oil return control. The degree to which the opening of the oil return valve 39 is opened is not particularly limited. For example, the opening degree of the oil return valve 39 is a predetermined ratio with respect to the valve opening by the oil return control of the oil return valve 39 in the cooling operation mode performed immediately before. Such a valve opening degree may be used, or the valve may be fully opened. By opening the valve opening of the oil return valve 39 in this manner, it becomes possible to send more refrigerating machine oil from the oil separator 23 to the injection pipe 30 through the oil return pipe 38.

(2-4-5) Normal oil distribution control of first to third injection valves 33a, 33b, and 33c Normal oil distribution control of first to third injection valves 33a, 33b, and 33c (distribution during oil leveling in cooling operation mode) In the control other than when the control is executed), the actuator control unit 74 sets the ratio of each of the first to third injection valves 33a, 33b, 33c to the first to third compressors 21a, 21b, Control is performed so as to be in proportion to the ratio of the rotation speed of 21c.

(2-4-6) Oil distribution control at the time of oil equalization of the first to third injection valves 33a, 33b, 33c In the oil distribution control at the time of oil equalization of the first to third injection valves 33a, 33b, 33c, an actuator control unit is used. 74 indicates that the ratio of each of the opening degrees of the second injection valve 33b and the third injection valve 33c to the opening degree of the first injection valve 33a is different from the rotation speed of the first compressor 21a. The compressor 21c is controlled so as to be larger than the ratio of each rotation speed. More specifically, the opening degrees of the second injection valve 33b and the third injection valve 33c are controlled to be slightly opened to secure a state in which a large amount of refrigerating machine oil returns to the second compressor 21b and the third compressor 21c. I do.

  Here, the valve opening degree of the first injection valve 33a is smaller than the control that maintains the valve opening degree of the second injection valve 33b and the third injection valve 33c as it is while reducing the valve opening degree of the first injection valve 33a. The control in which the opening degrees of the second injection valve 33b and the third injection valve 33c are increased by a predetermined opening degree while maintaining the same is preferable in that the discharge temperature of the compressor 21 can be kept low.

(2-5) Display control unit 75
The display control unit 75 is a functional unit that controls operations of the first remote controller 50a and the second remote controller 60a as display devices.

  The display control unit 75 causes the first remote controller 50a and the second remote controller 60a to output predetermined information in order to display information relating to the driving state and the situation to the administrator.

  For example, during execution of the cooling operation, the display control unit 75 causes the first remote controller 50a and the second remote controller 60a to display various information such as the set temperature.

(3) Flow of Refrigerant in Cooling Operation Mode Hereinafter, the flow of the refrigerant in the refrigerant circuit 10 in the cooling operation mode will be described.

  In the refrigeration apparatus 100, during operation, the refrigerant charged in the refrigerant circuit 10 mainly includes the compressor 21, the heat source side heat exchanger 25, the receiver 27, the subcooler 31, the heat source side expansion valve 28, and the use side expansion valve 54. , 64, and the cooling operation (refrigeration cycle operation) that circulates in the order of the use side heat exchangers 52, 62.

  When the cooling operation is started, the refrigerant is sucked into the compressor 21 in the refrigerant circuit 10 and is discharged after being compressed. Here, the low pressure in the refrigeration cycle is the suction pressure detected by the low pressure sensor 40a, the high pressure in the refrigeration cycle is the discharge pressure detected by the high pressure sensor 40c, and the intermediate pressure in the refrigeration cycle is the intermediate pressure sensor 40b. Is the ejection pressure detected by

  In the compressor 21, capacity control is performed according to the cooling load required by the first usage unit 50 and the second usage unit 60. Specifically, the target value of the suction pressure is set according to the cooling load required by the first usage unit 50 and the second usage unit 60, and the rotation speed of the compressor 21 is adjusted so that the suction pressure becomes the target value. Controlled. In the cooling operation mode, the compressor 21 performs load processing control or compressor leveling control.

  The gas refrigerant discharged from the compressor 21 flows into the gas side end of the heat source side heat exchanger 25 via the discharge side pipe 41. Here, the oil separator 23 provided in the middle of the discharge side pipe 41 separates the refrigerating machine oil from the refrigerant discharged from the compressor 21 and guides it to the oil return pipe 38 side. In the cooling operation mode, the oil return valve 39 performs oil return control or valve level oil control.

  The gas refrigerant that has flowed into the gas side end of the heat source side heat exchanger 25 exchanges heat with the heat source side air supplied by the heat source side fan 45 in the heat source side heat exchanger 25, radiates heat, condenses, and becomes a liquid refrigerant. And flows out from the liquid side end of the heat source side heat exchanger 25.

  The liquid refrigerant flowing out from the liquid side end of the heat source side heat exchanger 25 passes through the first heat source liquid side pipe 43 and the first heat source liquid side check valve 26 without branching and flowing to the second branch pipe 36 side. Then, it flows into the entrance of the receiver 27. The liquid refrigerant that has flowed into the receiver 27 flows out of the outlet of the receiver 27 after being temporarily stored in the receiver 27 as a saturated liquid refrigerant.

  The liquid refrigerant flowing out of the outlet of the receiver 27 flows through the second heat source liquid side pipe 44 and flows into the subcooler 31.

  The liquid refrigerant flowing into the subcooler 31 exchanges heat with the refrigerant flowing through the injection pipe 30 in the subcooler 31 and is further cooled to a supercooled liquid refrigerant, and the heat source side expansion of the subcooler 31 It flows out from the outlet on the valve 28 side. Here, the valve opening degree of the supercooling expansion valve 32 is controlled by the controller 70 so that the refrigerant flowing from the supercooler 31 to the heat source side expansion valve 28 has a predetermined positive supercooling degree. The detection value of the pressure sensor is controlled so as to satisfy a predetermined intermediate pressure condition.

  The liquid refrigerant flowing out of the outlet of the subcooler 31 on the heat source side expansion valve 28 side passes through a portion between the subcooler 31 and the heat source side expansion valve 28 in the second heat source liquid side pipe 44 and passes through the heat source side expansion valve. 28. At this time, a part of the liquid refrigerant flowing out of the outlet of the subcooler 31 on the heat source side expansion valve 28 side is discharged from a portion between the subcooler 31 and the heat source side expansion valve 28 in the second heat source liquid side pipe 44. It flows toward the branched injection pipe 30.

  The refrigerant flowing through the injection pipe 30 is decompressed by the supercooling expansion valve 32 until it reaches an intermediate pressure in the refrigeration cycle. The refrigerant flowing through the injection pipe 30 after being depressurized by the subcooling expansion valve 32 flows into the inlet of the subcooler 31 on the injection pipe 30 side. The refrigerant flowing into the inlet of the subcooler 31 on the side of the injection pipe 30 performs heat exchange with the refrigerant flowing on the side of the second heat source liquid side pipe 44 in the subcooler 31 and is heated to be a gas refrigerant. Then, the refrigerant heated in the supercooler 31 flows to the downstream side of the injection pipe 30 and is mixed by being combined with the refrigerating machine oil flowing through the oil return pipe 38, and the first to third injection branch pipes 33x, 33y, and 33z, respectively, and merge in the middle of the compression process of the first to third compressors 21a, 21b, and 21c. Here, the amount of the refrigerant flowing through the first to third injection branch pipes 33x, 33y, 33z is adjusted by the opening degree of each of the first to third injection valves 33a, 33b, 33c. In the cooling operation mode, the first to third injection valves 33a, 33b, and 33c perform normal oil distribution control or oil distribution control at the time of oil leveling.

  Since the heat source side expansion valve 28 is controlled to be fully opened in the cooling operation mode, the liquid refrigerant flowing into the heat source side expansion valve 28 from the second heat source liquid side pipe 44 is not depressurized, and the heat source side expansion valve 28 After that, it flows into the operating first usage unit 50 and second usage unit 60 via the liquid side closing valve 48 and the liquid side refrigerant communication pipe 6.

  The refrigerant flowing into the first usage unit 50 flows into the first usage-side expansion valve 54 through a part of the first usage-side liquid refrigerant pipe 59. The refrigerant flowing into the first usage-side expansion valve 54 is reduced in pressure by the first usage-side expansion valve 54 to a low pressure in the refrigeration cycle, and passes through the first usage-side liquid refrigerant pipe 59 to the first usage-side heat exchanger 52. Into the liquid side end of the The refrigerant flowing into the liquid side end of the first use side heat exchanger 52 performs heat exchange with the use side air supplied by the first use side fan 53 in the first use side heat exchanger 52 and evaporates. It becomes a gas refrigerant and flows out from the gas side end of the first use side heat exchanger 52. The gas refrigerant flowing out from the gas side end of the first use side heat exchanger 52 flows through the first use side gas refrigerant pipe 58 to the gas side refrigerant communication pipe 7.

  The refrigerant flowing into the second usage unit 60 flows through a part of the second usage-side liquid refrigerant pipe 69 into the second usage-side expansion valve 64, similarly to the first usage unit 50. The refrigerant flowing into the second usage-side expansion valve 64 is decompressed by the second usage-side expansion valve 64 to a low pressure in the refrigeration cycle, and passes through the second usage-side liquid refrigerant pipe 69 to the second usage-side heat exchanger 62. Into the liquid side end of the The refrigerant flowing into the liquid side end of the second use side heat exchanger 62 evaporates by performing heat exchange with the use side air supplied by the second use side fan 63 in the second use side heat exchanger 62, It flows out from the gas side end of the second use side heat exchanger 62 as a gas refrigerant. The gas refrigerant that has flowed out from the gas side end of the second use side heat exchanger 62 flows through the second use side gas refrigerant pipe 68 to the gas side refrigerant communication pipe 7.

  In this way, the refrigerant flowing out of the first usage unit 50 and the refrigerant flowing out of the second usage unit 60 join in the gas-side refrigerant communication pipe 7, and the gas-side closing valve 49, the four-way switching valve 24, and The refrigerant is again sucked into the compressor 21 via the suction pipe 42.

(4) Flow of Refrigerant in Heating Operation Mode Hereinafter, the flow of the refrigerant in the refrigerant circuit 10 in the heating operation mode performed for removing frost attached to the use-side heat exchangers 52 and 62 will be described.

  The heating operation is performed when the controller 70 determines that a predetermined heating operation start condition is satisfied during the cooling operation (for example, when the cooling operation is performed for a predetermined time or when the temperature of the heat exchanger to be defrosted is increased). When the temperature falls below the predetermined temperature), the operation is started.

  In the refrigerating apparatus 100, the refrigerant charged in the refrigerant circuit 10 during the heating operation mainly includes the compressor 21, the use side heat exchangers 52 and 62, the use side expansion valves 54 and 64, the receiver 27, and the heat source side expansion valve. 28, a heating operation (refrigeration cycle operation) circulating in the order of the heat source side heat exchanger 25 is performed.

  When the heating operation is started, the refrigerant is sucked into the compressor 21 in the refrigerant circuit 10 and is discharged after being compressed.

  Although not particularly limited, the compressor 21 is controlled so as to have a maximum rotation speed, for example. Specifically, while the rotation speed of the first compressor 21a is maximized, the second compressor 21b and the third compressor 21c are controlled to have a fixed rotation speed.

  The gas refrigerant discharged from the compressor 21 flows into the gas-side ends of the use-side heat exchangers 52 and 62 via the discharge-side pipe 41.

  The gas refrigerant that has flowed into the gas-side ends of the use-side heat exchangers 52 and 62 dissipates heat, condenses, and melts frost adhering to the use-side heat exchangers 52 and 62. At this time, the driving of the use side fans 53 and 63 is stopped.

  The refrigerant that has melted and condensed the frost in the use-side heat exchangers 52 and 62 passes through the use-side expansion valves 54 and 64 that are controlled to be fully open, and passes through the liquid-side refrigerant communication pipe 6 to the heat source unit 2. It flows into the liquid side.

  The refrigerant that has passed through the liquid side closing valve 48 of the heat source unit 2 flows so as to pass through the first branch check valve 35 in the first branch pipe 34 (the second heat source liquid side pipe 44 has a second heat source liquid side Since the stop valve 29 is provided, it does not flow in this direction.), And flows into the receiver 27. The refrigerant flowing into the receiver 27 flows through the second heat source liquid side pipe 44, passes through the subcooler 31, and is depressurized by the heat source side expansion valve 28 to a low pressure in the refrigeration cycle. Flows through the second branch check valve 37. During the heating operation, since the supercooling expansion valve 32 is controlled to be in a fully closed state, no refrigerant flows upstream of the injection pipe 30. Further, during the heating operation, the opening degree of the oil return valve 39 is controlled, so that the refrigerating machine oil flowing through the oil return pipe 38 passes through the first to third compressors 21 a, 21 b, 21c. In the heating operation mode, the oil return valve 39 performs the same oil return control as in the cooling operation mode. Further, in the heating operation mode, the first to third injection valves 33a, 33b, 33c perform the same normal oil distribution control as in the cooling operation mode.

  The refrigerant flowing so as to pass through the second branch check valve 37 of the second branch pipe 36 flows into the heat source side heat exchanger 25 via the first heat source liquid side pipe 43. The refrigerant that has flowed into the liquid end of the heat source side heat exchanger 25 exchanges heat with the heat source side air supplied by the heat source side fan 45 in the heat source side heat exchanger 25 and evaporates to become a gas refrigerant. It flows out from the gas side end of the side heat exchanger 25.

  The gas refrigerant flowing out of the heat source side heat exchanger 25 is sucked into the compressor 21 again via the four-way switching valve 24 and the suction side pipe 42.

  The heating operation is performed when the controller 70 determines that the predetermined heating operation end condition has been satisfied from the start of the heating operation (for example, the passage of a predetermined time or the temperature of the heat exchanger to be defrosted is equal to or higher than the predetermined temperature). Etc.), the operation is terminated, and the normal cooling operation is restarted.

(5) In the cooling operation mode, the load processing control of the compressor 21 and the compressor oil leveling control, the oil return control of the oil return valve 39 and the oil level increase control, the normal operation of the first to third injection valves 33a, 33b, and 33c. Process Flow When Controller 70 Executes Oil Distribution Control and Oil Equalization Oil Distribution Control Hereinafter, in the cooling operation mode, load processing control of compressor 21, compressor oil leveling control, and oil return control of oil return valve 39 are performed. FIG. 3 is a flowchart showing an example of the flow of processing performed by the controller 70 when executing the normal oil distribution control and the oil distribution control for the first to third injection valves 33a, 33b, and 33c. This will be described with reference to FIG.

  Here, the processing from the state in which the compressor 21 is started and all of the first compressor 21a, the second compressor 21b, and the third compressor 21c are driven and the refrigeration cycle is stabilized is described. explain.

  In step S11, the controller 70 executes load processing control in the compressor 21. That is, the rotation speed of the first compressor 21a is controlled such that the target value of the suction pressure set according to the cooling load required by the first usage unit 50 and the second usage unit 60 can be realized. You. In this state, both the second compressor 21b and the third compressor 21c are operated at a fixed rotation speed. Note that the upper limit of the rotation speed of the first compressor 21a is larger than the fixed rotation speeds of the second compressor 21b and the third compressor 21c, and usually (on average) is higher than the rotation speed of the first compressor 21a. The operation is performed so that is larger. Therefore, the refrigerating machine oil flowing through the oil return pipe 38 and the injection pipe 30 is mainly returned to the first compressor 21a having a high rotation speed.

  In step S12, the controller 70 executes oil return control in the oil return valve 39. That is, the valve opening of the oil return valve 39 is controlled such that the amount of oil rising from the compressor 21 is equal to the amount of circulation passing through the oil return valve 39.

  In step S13, the controller 70 executes the normal oil distribution control in the first to third injection valves 33a, 33b, 33c. That is, the respective opening degrees of the first to third injection valves 33a, 33b, 33c are controlled so as to be proportional to the rotation speeds of the corresponding first to third compressors 21a, 21b, 21c.

  In step S14, the controller 70 determines whether or not a predetermined determination time has elapsed after the processing in step S13 ends. That is, it is determined whether or not the operation has been performed for a predetermined determination time while the refrigeration cycle is stable. As a result, the first compressor 21a having a high rotation speed, the second compressor 21b and the third compressor 21c having a low rotation speed are all operated for a while, so that the second compressor 21b and the third compression It can be estimated that the refrigerating machine oil is in a shortage state in the machine 21c. If it is determined that the predetermined determination time has elapsed, the process proceeds to step S15, and if it is determined that the predetermined determination time has not elapsed, step S14 is repeated, and the elapse of the predetermined determination time is determined. wait. Note that, although not particularly limited, the predetermined determination time can be, for example, 30 minutes or 60 minutes.

  In step S15, the controller 70 executes compressor leveling control for the compressor 21. That is, the controller 70 reduces the rotation speed of the first compressor 21a, which is an inverter compressor, to a rotation speed lower than the fixed rotation speed of the second compressor 21b or the third compressor 21c, and Control is performed so as to maintain the operation state of the third compressor 21c at a fixed rotation speed. Thereby, the refrigerating machine oil flowing through the oil return pipe 38 and the injection pipe 30 is supplied to the second compressor 21b and the third compressor 21c having a higher rotation speed than the first compressor 21a whose rotation speed is controlled to be low. It will be easily returned.

  In step S16, the controller 70 executes oil leveling control for the oil return valve 39. That is, the controller 70 sets the oil return valve 39 based on the valve opening degree of the oil return valve 39 by the oil return control in the cooling operation mode performed when it is determined that the predetermined determination time has elapsed in step S14. Is controlled so as to increase the valve opening degree (for example, the opening degree becomes 150% of the reference). Thereby, more refrigerating machine oil can be sent from the oil separator 23 to the oil return pipe 38 and the injection pipe 30, and more refrigerating machine oil can be returned to the second compressor 21b and the third compressor 21c. It becomes possible.

  In step S17, the controller 70 executes oil leveling oil distribution control for the first to third injection valves 33a, 33b, 33c. That is, the controller 70 determines that the ratio of each of the opening degrees of the second injection valve 33b and the third injection valve 33c to the opening degree of the first injection valve 33a is different from the rotation speed of the first compressor 21a. By controlling the ratio so as to be larger than the ratio of the respective rotation speeds of the third compressor 21c, the second and third injection valves 33b and 33c are controlled so as to be slightly open. This makes it possible to ensure a state where the refrigerating machine oil is more easily returned to the second compressor 21b and the third compressor 21c than to the first compressor 21a.

  In step S18, the controller 70 determines whether or not a predetermined oil equalization time has elapsed from the time when the processing in step S17 ends. Here, when it is determined that the predetermined oil leveling time has elapsed, it is determined that the oil leveling process in the first compressor 21a, the second compressor 21b, and the third compressor 21c has been completed, and the process returns to step S11. Thus, the load processing control of the compressor 21, the oil return control of the oil return valve 39, and the normal oil distribution control of the first to third injection valves are restarted. If it is determined that the predetermined oil leveling time has not elapsed, step S18 is repeated, and the elapse of the predetermined oil leveling time is waited. Note that, although not particularly limited, the predetermined oil equalization time is a time shorter than the predetermined determination time, and may be, for example, 2 or 3 minutes.

(6) Features of refrigeration system 100 (6-1)
In the refrigeration apparatus 100 according to the present embodiment, in the cooling operation mode, by performing the above-described oil return control on the valve opening of the oil return valve 39, the refrigeration apparatus is in accordance with the refrigerant circulation amount and the oil rising rate of the compressor 21, that is, In addition, it is possible to cause the compressor 21 to return an appropriate amount of refrigerating machine oil according to the state of the refrigeration cycle, such as the number of revolutions of the compressor 21 and the high pressure, intermediate pressure, and low pressure in the refrigeration cycle. Thereby, the reliability of the compressor 21 can be improved.

  Here, in the compressor 21 of the present embodiment, a plurality of compressors of a first compressor 21a, a second compressor 21b, and a third compressor 21c are connected in parallel with each other, and an oil separator 23, an oil return The refrigerating machine oil is returned through a common part of the pipe 38 and the injection pipe 30. However, as compared with the second compressor 21b and the third compressor 21c of the fixed rotation speed type, the first compressor 21a, which is an inverter compressor, tends to have a higher rotation speed. Although a large amount of oil is discharged, the amount of the returned refrigerating machine oil is larger than that of the second compressor 21b and the third compressor 21c. For this reason, when the load processing control, which is the normal control, is performed in the compressor 21, the refrigerating machine oil tends to be short in the second compressor 21b and the third compressor 21c.

  On the other hand, in the compressor 21 of the present embodiment, the compressor leveling control is periodically performed. That is, control is performed to periodically lower the rotation speed of the first compressor 21a, which tends to increase the rotation speed. Thereby, the refrigerating machine oil flowing through the oil return pipe 38 and the injection pipe 30 is easily returned to the second compressor 21b and the third compressor 21c.

  Further, in the oil return valve 39 of the present embodiment, when the compressor oil leveling control is performed, the oil leveling control during oil leveling is performed, and the valve opening of the oil return valve 39 is greatly opened. That is, in a situation where the refrigerating machine oil is more easily returned to the second compressor 21b and the third compressor 21c than the first compressor 21a by the compressor oil leveling control, the valve opening of the oil return valve 39 is greatly increased. Accordingly, the amount of the refrigeration oil flowing through the oil return pipe 38 and the injection pipe 30 is increased, and more refrigeration oil can be returned to the second compressor 21b and the third compressor 21c.

  Moreover, in the first to third injection valves 33a, 33b, 33c of the above-described embodiment, the compressor leveling control is performed for the compressor 21 and the oil return valve 39 is controlled for increasing the oil level. At this time, oil distribution control at the time of oil leveling is performed, and the valve openings of the second injection valve 33b and the third injection valve 33c are controlled to be more open than the first injection valve 33a. Therefore, much more refrigerating machine oil can be easily returned to the second compressor 21b and the third compressor 21c.

(6-2)
In the refrigerating apparatus 100 of the present embodiment, the oil return pipe 38 is provided so as to join not the suction side of the compressor 21 but the injection pipe 30 connected during the compression process of the compressor 21. For this reason, it is possible to suppress that part of thermal energy of the high-temperature fluid (refrigerant and refrigerating machine oil) discharged from the compressor 21 is used to raise the temperature of the refrigerant sucked into the compressor 21. It has become.

(7) Modifications The above embodiment can be appropriately modified as shown in the following modifications. Note that each modification may be applied in combination with another modification as long as no contradiction occurs.

(7-1) Modification A
In the above embodiment, when the oil equalization is performed between the first compressor 21a, the second compressor 21b, and the third compressor 21c, the control to reduce the rotation speed of the first compressor 21a and the control of the oil return valve 39 are performed. The description has been given by taking as an example a case where mainly three controls of control for increasing the valve opening and control for relatively increasing the valve opening of the second and third injection valves 33b and 33c are performed.

  On the other hand, when equalizing the oil between the first compressor 21a, the second compressor 21b, and the third compressor 21c, only the control for lowering the rotation speed of the first compressor 21a is performed, and other operations are performed. The control may not be performed. Further, only the control for relatively increasing the valve opening of the second and third injection valves 33b and 33c may be performed, and other control may not be performed. Even in these cases, it is possible to obtain an oil equalizing effect between the first compressor 21a, the second compressor 21b, and the third compressor 21c, although it is inferior to the oil equalizing effect in the above embodiment. .

(7-2) Modification B
In the above-described embodiment, an example in which the end of the oil return pipe 38 on the side opposite to the oil separator 23 side is connected in the middle of the injection pipe 30 has been described.

  On the other hand, the connection destination of the oil return pipe is not limited to this, and for example, an end opposite to the oil separator 23 such as an oil return pipe 38a of the refrigeration apparatus 200 shown in FIG. The section may be connected in the middle of the suction side pipe 42.

  In this case, the refrigerating machine oil separated by the oil separator 23 is sent to the suction side of the compressor 21, but even in this case, the first compressor 21a and the second compressor 21b When performing oil equalization between the third compressors 21c, it is possible to obtain an oil equalization effect by reducing the rotation speed of the first compressor 21a. Also, at this time, by performing control to increase the valve opening of the oil return valve 39 provided in the oil return pipe 38a, more refrigeration oil can be returned to the second compressor 21b and the third compressor 21c. Will be possible.

(7-3) Modification C
In the above embodiment, the case where the downstream side of the injection pipe 30 is joined in the middle of the compression process of the compressor 21 has been described as an example.

  On the other hand, an injection pipe 30a whose downstream side is connected to the suction side of the compressor 21 may be used as in the refrigerating apparatus 300 shown in FIG. Since the refrigerant is connected in the middle of the compression process of the compressor 21, the amount of refrigerant drawn into the compressor 21 by the refrigerant flowing through the injection pipe 30 does not easily decrease.

  In addition, also in this modified example C, when the oil equalization is performed between the first compressor 21a, the second compressor 21b, and the third compressor 21c, similarly to the above embodiment, the rotation of the first compressor 21a is performed. By performing three controls of control to decrease the number, control to increase the valve opening of the oil return valve 39, and control to relatively increase the valve opening of the second and third injection valves 33b and 33c, It is also possible to return more refrigerating machine oil to the second compressor 21b and the third compressor 21c.

(7-4) Modification D
In the above-described Modification C, the refrigeration apparatus 300 including the injection pipe 30a whose downstream end is connected to the suction side of the compressor 21 has been described as an example.

  On the other hand, like the refrigerating device 400 shown in FIG. 6, the downstream side is provided with the injection pipe 30a connected to the suction side of the compressor 21 and, similarly to the modification B, on the opposite side to the oil separator 23. May be provided with an oil return pipe 38a whose end is connected in the middle of the suction side pipe 42.

  In this case, the refrigerating machine oil separated by the oil separator 23 is sent to the suction side of the compressor 21, but even in this case, the first compressor 21a and the second compressor 21b When performing oil equalization between the third compressors 21c, it is possible to obtain an oil equalization effect by reducing the rotation speed of the first compressor 21a. Also, at this time, by performing control to increase the valve opening of the oil return valve 39 provided in the oil return pipe 38a, more refrigeration oil can be returned to the second compressor 21b and the third compressor 21c. It is possible.

(7-5) Modification E
In the refrigerating apparatus 100 of the above embodiment, the oil return valve 39 constituted by an electronic expansion valve has been described as an example of the valve for adjusting the flow rate of the refrigerating machine oil in the oil return pipe 38.

  On the other hand, for example, a capillary tube 239 may be provided instead of the oil return valve 39 in the above embodiment and each modified example, as in a refrigeration apparatus 500 shown in FIG.

  Although it is not possible to control the capillary tube 239 itself, when performing oil equalization between the first compressor 21a, the second compressor 21b, and the third compressor 21c, the rotation speed of the first compressor 21a is reduced. It is possible to obtain the oil equalizing effect by the above, and at that time, by performing control to relatively increase the valve opening of the second and third injection valves 33b and 33c, the second compressor 21b and the third It is also possible to return more refrigerating machine oil to the compressor 21c.

(7-6) Modification F
In the refrigerating apparatus 100 of the above embodiment, the load processing control of the compressor 21, the oil return control of the oil return valve 39, and the normal oil distribution control of the first to third injection valves 33a, 33b, 33c are performed. The condition for switching to the compressor oil leveling control of the compressor 21, the oil leveling control of the oil return valve 39, and the oil leveling control of the first to third injection valves 33a, 33b, 33c is determined by a predetermined determination time. The description has been given by taking as an example that normal operation is continuously performed only for a while.

  On the other hand, the above condition is not limited to this, and may be, for example, a condition for switching when a predetermined time has come, or a condition for switching when the oil rising amount of the compressor has reached a predetermined amount. It may be.

(7-7) Modification G
In the above-mentioned embodiment and each modification, an example in which the injection pipe 30 is branched on the heat source side expansion valve 28 side of the subcooler 31 has been described.

  On the other hand, the injection pipe 30 may have a configuration in which the subcooler 31 branches off on the side opposite to the heat source side expansion valve 28 side.

(7-8) Modification H
In the above embodiment, the refrigeration apparatus 100 that cools the inside of the refrigerator or the showcase of the store has been described as an example.

  However, the present invention is not limited to this, and may be a refrigeration device that cools the inside of the transport container, or may be an air conditioning system (air conditioner) that achieves air conditioning by cooling the inside of a building or the like.

  INDUSTRIAL APPLICATION This invention can be utilized for a refrigerating apparatus.

2: Heat source unit 6: Liquid side refrigerant communication pipe 7: Gas side refrigerant communication pipe 10: Refrigerant circuit 20: Heat source unit control unit 21: Compressor 21a: First compressor (inverter compressor)
21b: Second compressor (compressor other than inverter compressor)
21c: Third compressor (compressor other than inverter compressor)
23: oil separator 25: heat source side heat exchanger 26: first heat source liquid side check valve 27: receiver 28: heat source side expansion valve 29: second heat source liquid side check valve 30: injection pipe (refrigerant supply pipe, Injection tube)
30a: Suction injection pipe (refrigerant supply pipe)
31: Subcooler 32: Subcooling expansion valve (intermediate expansion valve)
33: Injection valve 33a: First injection valve (flow control valve)
33b: 2nd injection valve (flow control valve)
33c: 3rd injection valve (flow control valve)
34: bypass pipe 35: bypass check valve 36: branch pipe 37: branch check valve 38: oil return pipe 38a: oil return pipe 39: oil return valve (flow rate adjusting mechanism)
40a: low pressure sensor 40b: intermediate pressure sensor 40c: high pressure sensor 41: discharge side pipe 42: suction side pipe (refrigerant supply pipe)
43: first heat source liquid side pipe 44: second heat source liquid side pipe 45: heat source side fan 47: discharge temperature sensor 50: first use unit 52: first use side heat exchanger 54: first use side expansion valve 57 : First usage unit control section 58: First usage side gas refrigerant pipe 59: First usage side liquid refrigerant pipe 60: Second usage unit 62: Second usage side heat exchanger 64: Second usage side expansion valve 67: Second usage unit control section 68: second usage side gas refrigerant pipe 69: second usage side liquid refrigerant pipe 70: controller (control section)
100, 200, 300, 400, 500: Refrigeration equipment

JP 2011-208860 A

Claims (1)

A plurality of compressors (21a, 21b, 21c) including at least one inverter compressor (21a) and connected in parallel with each other;
An oil separator (23) provided on the discharge side of the plurality of compressors;
A refrigerant supply pipe (30, 30a, 42) for supplying a refrigerant to the plurality of compressors;
An oil return pipe (38, 38a) connecting the oil separator (23) and the refrigerant supply pipe (30, 30a, 42);
A flow rate adjusting mechanism (39) provided on the oil return pipe and being a valve capable of controlling an opening degree;
With
In a situation where the rotation speed of the inverter compressor is higher than the rotation speeds of the compressors other than the inverter compressor, if the first predetermined condition is satisfied, the rotation speed of the inverter compressor is reduced to reduce the rotation speed. A first flow rate control for returning more refrigerating machine oil to the compressors other than the inverter compressor whose number has been reduced is performed, and the flow rate after starting the first flow rate control is greater than before starting the first flow rate control. Further comprising a first controller for controlling the flow rate adjusting mechanism (39) so that the flow rate in the adjusting mechanism (39) increases, or
In the refrigerant supply pipes (30, 30a, 42), a plurality of flow control valves (33a, 33a, 33y, 33z) provided corresponding to flow paths (33x, 33y, 33z) for supplying a refrigerant to each of the plurality of compressors. 33b, 33c), and in a situation where the rotation speed of the inverter compressor is higher than the rotation speeds of the compressors other than the inverter compressor, the flow control valve (33a) provided to correspond to the inverter compressor. ) And the flow control valves (33b, 33c) other than the flow control valves provided corresponding to the inverter compressor by changing the relative flow control degree when the second predetermined condition is satisfied. Performing a second flow rate control for returning more refrigerating machine oil to the compressors other than the inverter compressor, and starting the second flow rate control before starting the second flow rate control. A second controller for the flow rate in the amount adjusting mechanism (39) controls the flow rate adjusting mechanism (39) to increase, further comprising,
Refrigeration equipment (100, 200, 300, 400).

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