JP2015059718A - Refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating device that improves operating efficiency.SOLUTION: A refrigerating device comprises a heat source side unit 50, utilization side units 21 and 22, and four-way valves 55 and 56. A low-stage compressor 51a and a high-stage compressor 51c are connected in series via an intermediate-pressure pipe 51b. The four-way valves 55 and 56 switch a first state and a second state. The first state is a state where an intermediate-pressure refrigerant flows to a heat source side heat exchanger 53 after being discharged from the low-stage compressor 51a and flowing to the intermediate-pressure pipe 51b. The second state is a state where the intermediate-pressure refrigerant flows to a utilization side heat exchanger 22a.

Description

  The present invention relates to a refrigeration apparatus.

  As a conventional refrigeration apparatus, there is an air conditioner that includes a heat source side unit and a plurality of usage side units and can be operated simultaneously with air conditioning. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-130492) discloses air conditioning capable of cooling main (small heating capacity) operation, all-room cooling operation, heating main (cooling small capacity) operation, and all-room heating operation. A machine is disclosed.

  In a conventional refrigeration system capable of simultaneous cooling and heating, when there is only one compressor, each of the high pressure and low pressure values becomes one, and the refrigeration system operates at an excessively high or low differential pressure depending on the outside air temperature. It will be the situation that has been. It is contrary to the request | requirement of energy saving to operate | move by applying the high and low differential pressure larger than necessary in this way.

  On the other hand, in the air conditioner described in Patent Document 1 (Japanese Patent Laid-Open No. 2003-130492) described above, the discharge pressure of the inverter compressor and the constant speed compressor arranged in parallel separately from the inverter compressor, It can be set separately. And each discharge pressure of the constant speed compressor used in the refrigerating cycle of air_conditionaing | cooling operation and the inverter compressor used in the refrigerating cycle of heating operation is set so that the efficiency in each operation may become high.

  However, there is a demand for a refrigeration apparatus having a further refrigeration cycle configuration and having high operating efficiency.

  An object of the present invention is to provide a refrigeration apparatus with improved operating efficiency.

  The refrigeration apparatus according to the first aspect of the present invention includes a heat source side unit, a first usage side unit, a second usage side unit, and a switching mechanism. The heat source side unit has a compression mechanism including a low stage compressor and a high stage compressor, a heat source side heat exchanger, and a heat source side expansion mechanism. The first usage-side unit includes a first usage-side heat exchanger and a first usage-side expansion mechanism. The second usage side unit includes a second usage side heat exchanger and a second usage side expansion mechanism. The switching mechanism switches the path of the refrigerant flowing from the compression mechanism to the heat source side heat exchanger, the first usage side heat exchanger, and the second usage side heat exchanger. The low-stage compressor and the high-stage compressor are connected in series via an intermediate pressure pipe. The switching mechanism is a mechanism that switches between the first state and the second state. The first state is a state where the intermediate pressure refrigerant discharged from the low stage compressor and flowing to the intermediate pressure pipe flows to the heat source side heat exchanger. The second state is a state in which the intermediate pressure refrigerant flows to the first usage side heat exchanger or the second usage side heat exchanger.

  Here, the intermediate-pressure refrigerant discharged from the low-stage compressor and flowing into the intermediate-pressure pipe after the configuration in which the low-stage compressor and the high-stage compressor are connected in series is the heat source side in the first state. The refrigerant circuit is configured to flow to the heat exchanger and to flow to the first usage side heat exchanger or the second usage side heat exchanger in the second state. According to the refrigeration apparatus according to the present invention, for example, when the outside air temperature is low and the high-pressure refrigerant is not required in the heat source side heat exchanger, the switching mechanism can be set to the first state to improve the operation efficiency. Also, for example, when the outside temperature is high, the first usage side heat exchanger functions as an evaporator, and the second usage side heat exchanger needs to function as a radiator for a small heat load. The operating efficiency of the refrigeration apparatus can be improved by setting the mechanism to the second state and sending the intermediate pressure refrigerant to the second use side heat exchanger.

  The refrigeration apparatus according to the second aspect of the present invention is the refrigeration apparatus according to the first aspect, further comprising a control unit that controls the switching mechanism. The control unit has an intermediate pressure use operation mode in which the first use side heat exchanger functions as an evaporator and the second use side heat exchanger functions as a radiator. In this intermediate pressure use operation mode, the control unit is configured such that the intermediate pressure refrigerant discharged from the low-stage compressor and flowing into the intermediate pressure pipe is the heat source side heat exchanger, the first use side heat exchanger, or the second use side. The switching mechanism is controlled to flow directly to the heat exchanger.

  Here, since the intermediate pressure use operation mode is provided as the operation mode, not only the high-pressure refrigerant discharged from the conventionally used high-stage compressor but also the intermediate-pressure refrigerant is positively used. Driving efficiency can be improved.

  The refrigeration apparatus according to the third aspect of the present invention is the refrigeration apparatus according to the first aspect, further comprising a control unit that controls the switching mechanism. The control unit has a first mixed operation mode and a second mixed operation mode. In the first mixed operation mode and the second mixed operation mode, the first usage-side heat exchanger functions as an evaporator, and the second usage-side heat exchanger functions as a radiator. In the first mixed operation mode, the control unit controls the switching mechanism so that the intermediate pressure refrigerant discharged from the low-stage compressor and flowing to the intermediate pressure pipe flows to the second usage-side heat exchanger. Moreover, a control part controls a switching mechanism so that the high pressure refrigerant | coolant discharged from the high stage compressor may flow into a 2nd utilization side heat exchanger in 2nd mixed operation mode.

  Here, the first mixed operation mode and the second mixture are used as an operation mode in which the use side unit in which the use side heat exchanger functions as an evaporator and the use side unit in which the use side heat exchanger functions as a radiator are mixed. An operation mode is provided. And with respect to the 2nd utilization side heat exchanger, an intermediate pressure refrigerant flows in the 1st mixed operation mode, and a high pressure refrigerant flows in the 2nd mixed operation mode. As described above, in this refrigeration apparatus, in addition to the selection of flowing the high-pressure refrigerant to the usage-side heat exchanger, the selection of flowing the intermediate-pressure refrigerant to the usage-side heat exchanger is possible. When the heat load of the space is small, it is possible to improve the operation efficiency of the entire refrigeration apparatus using the intermediate pressure refrigerant.

  A refrigeration apparatus according to a fourth aspect of the present invention is the refrigeration apparatus according to the third aspect, wherein the control unit causes the intermediate pressure refrigerant to flow to the second usage-side heat exchanger in the first mixed operation mode. In addition, the switching mechanism is controlled so that the high-pressure refrigerant discharged from the high-stage compressor flows to the heat source side heat exchanger.

  In the first mixed operation mode of the refrigeration apparatus, the high-pressure refrigerant flows through the heat source side heat exchanger to dissipate heat, while the intermediate pressure refrigerant flows through the second use side heat exchanger to dissipate heat. Turn on heating. The refrigerant after radiating heat in these heat exchangers flows to the first usage side heat exchanger and evaporates. If the control logic is configured to select the first mixed operation mode when, for example, the outside air temperature is high and the heat load of the heating of the second usage-side unit is small, the operation efficiency of the refrigeration apparatus is improved.

  The refrigeration apparatus according to the fifth aspect of the present invention is the refrigeration apparatus according to the third aspect or the fourth aspect, wherein the heat source side unit includes a heat source side fan for sending outside air to the heat source side heat exchanger, and an outside air temperature. And an outside air temperature sensor. In the second mixed operation mode, the control unit controls the switching mechanism so that the high-pressure refrigerant flows to the second usage-side heat exchanger and the intermediate-pressure refrigerant flows to the heat source-side heat exchanger. Then, the pressure of the intermediate pressure refrigerant is adjusted by changing the rotation speed of the heat source side fan according to the outside air temperature.

  Here, for example, when the outside air temperature is not high, the first usage-side heat exchanger that functions as an evaporator needs a low-pressure refrigerant, and the second usage-side heat exchanger that functions as a radiator requires a high-pressure refrigerant. Then, the control unit causes the intermediate pressure refrigerant to flow to the heat source side heat exchanger. Thereby, the operating efficiency of the refrigeration apparatus can be kept high without unnecessarily lowering the pressure of the high-pressure refrigerant and reducing the operating efficiency. Further, the rotational speed of the heat source side fan is changed here according to the outside air temperature so that the refrigerant having a pressure matching the outside air temperature flows to the heat source side heat exchanger. By performing such control, driving efficiency can be further improved. Specifically, for example, when the outside air temperature becomes low, it is conceivable to perform a control of increasing the pressure of the intermediate pressure refrigerant by decreasing the rotation speed of the heat source side fan.

  A refrigeration apparatus according to a sixth aspect of the present invention is the refrigeration apparatus according to any one of the third to fifth aspects, wherein the control unit switches from the first mixed operation mode to the second mixed operation mode. The low-stage compressor or the high-stage compressor is temporarily stopped, the refrigerant path is switched by the switching mechanism, and then both the low-stage compressor and the high-stage compressor are returned to the operating state.

  When switching from the first mixed operation mode in which the intermediate pressure refrigerant flows to the second usage side heat exchanger to the second mixed operation mode in which the high pressure refrigerant flows to the second usage side heat exchanger, the state of the switching mechanism changes. However, here, the magnitude of the generated sound can be suppressed by temporarily stopping the low-stage compressor or the high-stage compressor. In addition, the state of the switching mechanism is surely switched by switching the state after the pressure difference around the switching mechanism becomes small.

  According to the refrigeration apparatus according to the present invention, it is possible to flow the intermediate pressure refrigerant to the heat source side heat exchanger and also to the utilization side heat exchanger, and each refrigerant having an appropriate pressure according to the heat load and the outside air temperature is supplied. Since it becomes possible to flow through the heat exchanger, the operation efficiency is improved.

The refrigerant circuit figure which shows the steady cooling state of the air conditioner which is the freezing apparatus which concerns on one Embodiment of this invention. The control block diagram of an air conditioner. The refrigerant circuit diagram which shows the transition state from the air-conditioner's air-conditioning state to the air-conditioning mixed / air-cooling main state (the outside air temperature is medium / low temperature). The refrigerant circuit diagram which shows the air conditioning mixed air-conditioning mixed / cooling main state (outside air temperature is medium temperature / low temperature). The refrigerant circuit diagram which shows the transition state from the air-conditioner mixed air-conditioning mixed / cooling main state (outside temperature is medium temperature / low temperature) to the mixed cooling / heating / heating main state (outside air temperature is low). The refrigerant circuit diagram which shows the air conditioning mixing / heating main state (outside temperature is low temperature) of an air conditioner. The refrigerant circuit diagram which shows the air conditioning mixing / cooling main state (air temperature is high) of an air conditioner. The refrigerant circuit diagram which shows the transition state from the air-conditioner mixed air-conditioning mixed / cooling main state (the outside air temperature is high) to the cooling / heating mixed / heating main state (the outside air temperature is high). The refrigerant circuit figure which shows the air conditioning mixing / heating main state (outside temperature is high temperature) of an air conditioner. The refrigerant circuit diagram which shows the transition state from the air-conditioner mixed air-conditioning mixed / heating main state (the outside air temperature is high) to the steady heating state. The refrigerant circuit figure which shows the steady heating state of an air conditioner. The refrigerant circuit diagram which shows the transition state from the air-conditioner mixed air-conditioning mixed / cooling main state (the outside air temperature is high) to the cooling / heating mixed / cooling main state (the outside air temperature is medium / low temperature). The refrigerant circuit diagram which shows the transition state from the air-conditioner mixed air-conditioning mixed / heating main state (the outside air temperature is high / medium temperature) to the air-conditioning mixed / heating main state (the outside air temperature is medium / low temperature).

  Hereinafter, an air conditioner as a refrigeration apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(1) Configuration of Air Conditioner FIG. 1 is a schematic configuration diagram of a refrigerant circuit of an air conditioner. An air conditioner is an apparatus used for indoor air conditioning such as a building by performing a vapor compression refrigeration cycle operation.

  The air conditioner mainly includes one heat source side unit 50, a plurality (three in this case) of use side units 21, 22, 23, branch units 31, 32, 33, refrigerant communication tubes 41, 42, 43, and is configured such that an air-conditioning mixed operation in which air-conditioning is selected for each use-side unit is possible. That is, the refrigerant circuit of the air conditioner is configured by connecting the heat source side unit 50, the use side units 21, 22, 23, the branch units 31, 32, 33, and the refrigerant communication tubes 41, 42, 43. It is configured. The refrigerant communication pipe 41 extends from the heat source side unit 50 to the use side units 21, 22, and 23, and in the middle, the first refrigerant communication pipe 41a, the second refrigerant communication pipe 41b, and the third refrigerant communication pipe 41c. Branched. The refrigerant communication pipe 42 extends from the heat source side unit 50 to the use side units 21, 22, and 23, and in the middle thereof, is connected to the first refrigerant communication pipe 42a, the second refrigerant communication pipe 42b, and the third refrigerant communication pipe 42c. Branched. The refrigerant communication pipe 43 extends from the heat source side unit 50 to the use side units 21, 22, and 23. In the middle of the refrigerant communication pipe 43, the first refrigerant communication pipe 43a, the second refrigerant communication pipe 43b, and the third refrigerant communication pipe 43c are connected. Branched. And R32 refrigerant | coolant is enclosed with the refrigerant circuit.

  As shown in FIG. 2, the air conditioner is configured by electrically connecting a heat source side unit control unit in the heat source side unit 50 and a use side unit control unit in the use side units 21, 22, and 23. Controlled by the control unit 60. The control unit 60 is input with detection values from the sensors (including the outside air temperature sensor 65) of the heat source side unit 50 and the use side units 21, 22, and 23, and operation contents including a set temperature from the remote controller. Is entered. The control unit 60 sends an operation instruction to each actuator shown in FIG. 2 of the heat source side unit 50, the use side units 21, 22, 23 and the branch units 31, 32, 33. Various controls performed by the control unit 60 will be described in detail later.

(1-1) Usage-side units Usage-side units 21, 22, and 23 are installed on the indoor ceiling of a building or the like by embedding or hanging, or are installed on an indoor wall surface by wall hanging or the like. . The use side units 21, 22, and 23 are connected to the heat source side unit 50 via the refrigerant communication tubes 41, 42, and 43 and the branch units 31, 32, and 33, and constitute a part of the refrigerant circuit.

  Next, the configuration of the use side units 21, 22, and 23 will be described. The first usage-side unit 21 includes a first usage-side heat exchanger 21a and a first usage-side expansion valve 21b. The second usage-side unit 22 includes a second usage-side heat exchanger 22a and a second usage-side expansion valve 22b. The third usage-side unit 23 includes a third usage-side heat exchanger 23a and a third usage-side expansion valve 23b. The use-side heat exchangers 21a, 22a, and 23a are heat exchangers that process indoor air conditioning loads (heat loads) by exchanging heat between the refrigerant and room air.

  In addition, although the use side unit demonstrates three air conditioners here, also when more use side units are connected to one heat source side unit, and comprise the one refrigerant circuit. The present invention is applicable.

(1-2) Branch unit Branch units 31, 32, and 33 are installed in the vicinity of indoor use side units 21, 22, and 23 such as buildings, and are used together with refrigerant communication tubes 41, 42, and 43. It is interposed between the side units 21, 22, 23 and the heat source side unit 50 and constitutes a part of the refrigerant circuit. The branch units 31, 32, and 33 may be installed one by one for the three usage-side units 21, 22, and 23, or a plurality of usage-side units that have the same cooling / heating switching timing may be provided. It may be connected to one branch unit.

  The branch units 31, 32 and 33 mainly include a first branch path including the first branch unit switching valves 31a, 32a and 33a and a second branch including the second branch unit switching valves 31b, 32b and 33b. Road. The first branch unit switching valves 31a, 32a, and 33a are electromagnetic valves that switch between communication and non-communication between the second refrigerant communication pipe 42 and the use-side heat exchangers 21a, 22a, and 23a. The second branch unit switching valves 31b, 32b, 33b are electromagnetic valves that switch between communication and non-communication between the third refrigerant communication pipe 43 and the use side heat exchangers 21a, 22a, 23a.

(1-3) Heat source side unit The heat source side unit 50 is installed on the roof of a building or the like, or around the building, and is used on the usage side via the refrigerant communication pipes 41, 42, 43 and the branch units 31, 32, 33. It is connected to the units 21, 22, 23 and constitutes a part of the refrigerant circuit.

  The heat source side unit 50 is mainly composed of a compression mechanism 51 including a low stage compressor 51a and a high stage compressor 51c, a heat source side heat exchanger 53, a heat source side expansion valve 54, and two four paths constituting a switching mechanism. The switching valves 55 and 56 and the heat source side fan 59 are provided.

  As shown in FIG. 1, the low-stage compressor 51a and the high-stage compressor 51c are connected in series via an intermediate pressure pipe 51b. The low-stage compressor 51a and the high-stage compressor 51c are positive displacement compressors such as a rotary type and a scroll type, which suck in refrigerant and compress and discharge the sucked refrigerant. Here, the refrigerant discharged from the low stage compressor 51a to the intermediate pressure pipe 51b is referred to as intermediate pressure refrigerant, and the refrigerant discharged from the high stage compressor 51c to the first four-way switching valve 55 side is referred to as high pressure refrigerant. .

  A bypass circuit is provided in both the low-stage compressor 51a and the high-stage compressor 51c. A check valve 57 is provided in the bypass circuit of the low-stage compressor 51a, and a check valve 58 is provided in the bypass circuit of the high-stage compressor 51c. The refrigerant flows through these bypass circuits when one of the low-stage compressor 51a and the high-stage compressor 51c is stopped. For example, the refrigerant passes through the check valve 57 when the low stage compressor 51a shown in FIG. 5 is stopped, and the refrigerant passes through the check valve 58 when the high stage compressor 51c shown in FIG. 12 is stopped. To do.

  The heat source side heat exchanger 53 is a heat exchanger that functions as a heat radiator or an evaporator of the refrigerant by exchanging heat between the refrigerant and the outdoor air (outside air).

  The heat source side expansion valve 54 is an electric expansion valve that performs decompression of the refrigerant flowing through the heat source side unit 50, and is provided between the heat source side heat exchanger 53 and the first refrigerant communication pipe 41.

  The first four-way switching valve 55 has a heat source side heat dissipation state in which the heat source side heat exchanger 53 functions as a refrigerant radiator, and a heat source side evaporation state in which the heat source side heat exchanger 53 functions as a refrigerant evaporator. Switchable motorized valve. The first port 71 of the four-way switching valve 55 is connected to the discharge side of the high stage compressor 51c, the second port 72 is connected to the gas side of the heat source side heat exchanger 53, and the third port 73 is The second four-way switching valve 56 is connected to the third port 83, and the fourth port 74 is connected to the second refrigerant communication pipe 42. The first four-way switching valve 55 connects the first port 71 and the second port 72 and connects the third port 73 and the fourth port 74 (corresponding to the heat source side heat dissipation state; for example, FIG. (Refer to the state of the four-way switching valve 55), the second port 72 and the third port 73 are connected and the first port 71 and the fourth port 74 are connected (heat radiation to the heat source side low temperature outside air, or , Corresponding to the heat source side evaporation state; for example, it is possible to perform switching with the four-way switching valve 55 in FIGS. 4 and 11).

  The second four-way switching valve 56 includes a state in which the intermediate pressure pipe 51b connecting the low stage compressor 51a and the high stage compressor 51c is communicated with the third refrigerant communication pipe 43, and the intermediate pressure pipe 51b in the first state. This is a motor-operated valve capable of switching between a state in which the four-way switching valve 55 communicates with the third port 73. The first port 81 of the four-way switching valve 56 is connected to the third refrigerant communication pipe 43, the second port 82 is connected to the intermediate pressure pipe 51b, and the third port 83 is the first four-way switching. It is connected to the third port 73 of the valve 55, and the fourth port 84 is connected to the suction side of the low-stage compressor 51a.

  The two four-way switching valves 55 and 56 constituting the switching mechanism are mechanisms that switch between the first state and the second state. For example, as shown in FIG. 4, the first state is a state in which the intermediate pressure refrigerant discharged from the low-stage compressor 51 a and flowing to the intermediate pressure pipe 51 b flows to the heat source side heat exchanger 53. For example, as shown in FIG. 7, the second state is a state in which the intermediate pressure refrigerant discharged to the intermediate pressure pipe 51b flows into any one or a plurality of use side heat exchangers 21a, 22a, and 23a.

Note that the switching mechanism configured by the two four-way switching valves 55 and 56 is not limited to the mechanism configured by the four-way switching valve, and for example, by combining a plurality of electromagnetic valves. It may be configured to have the same function of switching the direction of refrigerant flow.
(2) Operation of the air conditioner As the operation mode of the air conditioner according to the present embodiment, a steady cooling operation mode 60a for cooling all of the use side units 21, 22, 23, and the use side units 21, 22, 23. The control unit 60 has a steady heating operation mode 60b that heats all of the usage-side units 21, 22, and 23 in accordance with the air conditioning load and an air-conditioning mixed operation mode 60c. In the cooling / heating mixed operation mode 60c, a cooling operation is performed in a part of the use side units 21, 22, 23, and a heating operation is performed in the remaining part or all. Hereinafter, operations in the three operation modes of the air conditioner will be described.

(2-1) Steady Cooling Operation Mode In the steady cooling operation mode 60a for cooling all of the use side units 21, 22, 23, each actuator (valve) of the refrigerant circuit of the air conditioner is as shown in FIG. It becomes a state. The heat source side heat exchanger 53 into which the high-pressure refrigerant flows functions as a refrigerant radiator, and the opening degree of the heat source side expansion valve 54 is adjusted so that the refrigerant is not depressurized as much as possible (for example, fully opened). In the branch units 31, 32, and 33, the first branch unit switching valves 31a, 32a, and 33a are closed, and the second branch unit switching valves 31b, 32b, and 33b are opened, and the use side heat exchangers 21a and 22a are opened. , 23a function as a refrigerant evaporator. The refrigerant evaporated in the use side heat exchangers 21a, 22a, and 23a is sucked into the low-stage compressor 51a through the third refrigerant communication pipe 43 and the second four-way switching valve 56. In addition, the opening degree of the use side expansion valves 21b, 22b, and 23b is adjusted according to the cooling load of each use side unit 21, 22, and 23.

(2-2) Steady Heating Operation Mode In the steady heating operation mode 60b for heating all of the use side units 21, 22, and 23, each actuator (valve) of the refrigerant circuit of the air conditioner is as shown in FIG. State. The high-pressure refrigerant discharged from the high-stage compressor 51c flows from the first four-way switching valve 55 to the second refrigerant communication pipe 42, and from the branch units 31, 32, 33 to the use side units 21, 22, 23. And flow into. In the branch units 31, 32, and 33, the first branch unit switching valves 31a, 32a, and 33a are opened, and the second branch unit switching valves 31b, 32b, and 33b are closed, and the usage-side heat exchangers 21a and 22a are closed. , 23a function as a refrigerant radiator. The refrigerant condensed in the use side heat exchangers 21a, 22a, 23a flows to the heat source side heat exchanger 53 via the heat source side expansion valve 54, and the refrigerant evaporated there is a first and second four-way switching valve 55, 56 and sucked into the low-stage compressor 51a. The opening degree of the heat source side expansion valve 54 is adjusted so as to depressurize the refrigerant. The use side expansion valves 21b, 22b, and 23b are adjusted in opening according to the heating load of each use side unit 21, 22, and 23.

(2-3) Air-conditioning mixed operation mode In the air-conditioning mixed operation mode 60c in which the air-conditioning operation is performed with some of the use-side units 21, 22, and 23 while the air-conditioning operation is performed with the remaining part or all of the units. Each actuator (valve) is controlled so that a part of the exchangers 21a, 22a, and 23a function as an evaporator and the other part (or all the others) function as a radiator. The heat source side heat exchanger 53 of the heat source side unit 50 functions as a radiator or an evaporator according to the balance between the cooling load and the heating load of the use side units 21, 22, and 23. When the heat source side heat exchanger 53 functions as a radiator, the opening degree of the heat source side expansion valve 54 is adjusted so as not to depressurize the refrigerant as much as possible, and when the heat source side heat exchanger 53 functions as an evaporator. The opening degree is adjusted so as to depressurize the refrigerant. In the branch units 31, 32, and 33, the first branch unit switching valves 31a, 32a, and 33a corresponding to the use side units 21, 22, and 23 that function as an evaporator are closed, and the second branch unit switching valves 31b, Open 32b and 33b. On the other hand, the 1st branch unit switching valve 31a, 32a, 33a corresponding to the utilization side unit 21,22,23 made to function as a heat radiator is opened, and the 2nd branch unit switching valve 31b, 32b, 33b is closed.

  The controller 60 has an intermediate pressure use operation mode as one of the air-conditioning mixed operation mode 60c. In this intermediate pressure use operation mode, the control unit 60 causes the intermediate pressure refrigerant discharged from the low-stage compressor 51a and flowing to the intermediate pressure pipe 51b to be the heat source side heat exchanger 53, or any one or more of them. The two four-way switching valves 55 and 56 are controlled so as to flow directly to the use side heat exchangers 21a, 22a and 23a.

  The refrigerant circuit of the air conditioner shown in FIG. 7 allows the first and third usage-side heat exchangers 21a and 23a to function as an evaporator and the second usage-side heat exchanger 22a to function as a radiator. This shows an intermediate pressure using operation mode mainly for cooling when the temperature is high. In this mode (hereinafter referred to as the first mixed operation mode), the four-way switching valves 55 and 56 are arranged so that the intermediate-pressure refrigerant that has flowed through the intermediate-pressure pipe 51b is directed directly to the second usage-side heat exchanger 22a. Is controlled.

  Further, the refrigerant circuit of the air conditioner shown in FIG. 4 causes the first and third usage-side heat exchangers 21a and 23a to function as an evaporator and the second usage-side heat exchanger 22a to function as a radiator. FIG. 6 shows an intermediate pressure using operation mode mainly for cooling when the outside air temperature is low (or medium). In this mode (hereinafter referred to as the second mixed operation mode), the four-way switching valves 55 and 56 are controlled so that the intermediate-pressure refrigerant that has flowed through the intermediate-pressure pipe 51 b is directed directly to the heat source side heat exchanger 53. The

  That is, the first and third usage-side heat exchangers 21a and 23a function as an evaporator, and the second usage-side heat exchanger 22a functions as a radiator. The control unit 60 has a first mixed operation mode and a second mixed operation mode that are different from each other. In the first mixed operation mode, since the outside air temperature is high and the loads on the first and third usage-side units 21 and 23 are large, the high-pressure refrigerant is sent to the heat source side heat exchanger 53, and the intermediate-pressure refrigerant is the second pressure refrigerant. It is sent to the use side heat exchanger 22a. In the second mixed operation mode, since the outside air temperature is not high and the loads on the first and third usage-side units 21 and 23 are small, the intermediate-pressure refrigerant is sent to the heat source-side heat exchanger 53 and the second usage-side heat exchange is performed. A high-pressure refrigerant is sent to the vessel 22a.

(2-4) Transition of operation mode Next, an example of transition from the steady cooling operation mode 60a to the cooling / heating mixed operation mode 60c, an example of transition from the cooling / heating mixed operation mode 60c to another cooling / heating mixed operation mode 60c, and cooling / heating mixed An example of the transition from the operation mode 60c to the steady heating operation mode 60b will be shown and described.

(2-4-1) Transition from the steady cooling operation mode to the mixed cooling and heating operation mode As the setting of the use side unit 22 is switched from the cooling to the heating from the steady cooling operation mode 60a shown in FIG. 1 described above. When shifting to the cooling / heating mixed operation mode 60c shown in FIG. 4, the control unit 60 passes the state of the refrigerant circuit shown in FIG. When the outside air temperature decreases and the setting of the use side unit 22 is switched from cooling to heating, the control unit 60 reduces the rotational speed of the high stage compressor 51c and the pressure around the first four-way switching valve 55. After the difference becomes small, the state of the first four-way selector valve 55 is switched. Then, after reaching the state of the refrigerant circuit shown in FIG. 4, the rotational speed of the high stage compressor 51 c is gradually increased, and the refrigerant discharged from the high stage compressor 51 c is used as the usage side heat exchanger of the usage side unit 22. Send to 22a. On the other hand, as described above, the intermediate pressure refrigerant discharged from the low stage compressor 51a and flowing to the intermediate pressure pipe 51b is sent to the heat source side heat exchanger 53.

  In the cooling / heating mixed operation mode 60c mainly shown in FIG. 4, the control unit 60 sets the rotation speed of the heat source side fan 59 of the heat source side unit 50 according to the value of the outside air temperature detected by the outside air temperature sensor 65. change. Specifically, when the outside air temperature is lowered, the control unit 60 performs fan control that increases the pressure of the intermediate pressure refrigerant by reducing the rotation speed of the heat source side fan 59.

(2-4-2) Transition from a cooling main body to a heating main body accompanying a change in the outside air temperature in the cooling / heating mixed operation mode As shown in FIG. 4 described above, the cooling-main mixed cooling / heating operation when the outside air temperature is low (or medium temperature). From the mode 60c, when the setting of the use side unit 23 is switched from cooling to heating, the control unit 60 moves to the heating main cooling / heating mixed operation mode 60c shown in FIG. Let the state go through. Here, the utilization side expansion valve 23b of the utilization side unit 23 and the heat source side expansion valve 54 of the heat source side unit 50 are closed to create a state in which no refrigerant flows to the utilization side heat exchanger 23a and the heat source side heat exchanger 53. Then, the low-stage compressor 51a is gradually stopped, and the state of the second four-way selector valve 56 is switched after the pressure difference around the second four-way selector valve 56 becomes small. Thereafter, the low-stage compressor 51a and the high-stage compressor 51c are driven in the state of the refrigerant circuit in the heating / cooling / heating mixed operation mode 60c when the outside air temperature is low as shown in FIG. In the air-conditioning mixed operation mode 60c shown in FIG. 6, the high-pressure refrigerant discharged from the high-stage compressor 51c flows directly to the use side heat exchangers 22a and 23a functioning as radiators, and these use side heat exchangers 22a. , 23a branch through the first refrigerant communication pipe 41 into a use side heat exchanger 21a that functions as an evaporator of the first use side unit 21 and a heat source side heat exchanger 53. Flows in. Then, when the state of the second four-way switching valve 56 is switched, the refrigerant evaporated in the heat source side heat exchanger 53 is sucked into the low-stage compressor 51a and is evaporated in the use side heat exchanger 21a. The refrigerant is sucked into the high stage compressor 51c through the third refrigerant communication pipe 43 and the intermediate pressure pipe 51b.

(2-4-3) Transition from the cooling main body to the heating main body in the cooling / heating mixed operation mode when there is no outside air temperature change From the cooling main heating / cooling / heating mixed operation mode 60c when the outside air temperature is high, as shown in FIG. When the setting of the use side unit 23 is switched from cooling to heating, the control unit 60 changes to FIG. 8 when moving to the heating / cooling / heating mixed operation mode 60c (FIG. 9) when the outside air temperature is high. The state of the refrigerant circuit shown is routed. Here, the utilization side expansion valve 23b of the utilization side unit 23 and the heat source side expansion valve 54 of the heat source side unit 50 are closed to create a state in which no refrigerant flows to the utilization side heat exchanger 23a and the heat source side heat exchanger 53. The high stage compressor 51c is gradually stopped, and the state of the first four-way switching valve 55 is switched after the pressure difference around the first four-way switching valve 55 becomes small. Thereafter, the low-stage compressor 51a and the high-stage compressor 51c are driven in the state of the refrigerant circuit of the heating / cooling / heating mixed operation mode 60c when the outside air temperature is high or medium as shown in FIG. . In the air-conditioning mixed operation mode 60c shown in FIG. 9, the high-pressure refrigerant discharged from the high-stage compressor 51c flows directly to the usage-side heat exchangers 22a and 23a that function as radiators, and the usage-side heat exchanger 22a. , 23a branch through the first refrigerant communication pipe 41 into a use side heat exchanger 21a that functions as an evaporator of the first use side unit 21 and a heat source side heat exchanger 53. Flows in. The refrigerant evaporated in the use side heat exchanger 21a is sucked into the low stage compressor 51a through the third refrigerant communication pipe 43, while the refrigerant evaporated in the heat source side heat exchanger 53 The refrigerant is sucked into the high stage compressor 51c via the switching valves 55 and 56 and the intermediate pressure pipe 51b.

  In addition, in the heating / cooling mixed heating operation mode 60c shown in FIG. 9, when the outside air temperature is high, the control unit 60 reduces the rotation speed of the heat source side fan 59 of the heat source side unit 50 to reduce the pressure of the intermediate pressure refrigerant. Control the lowering fan.

(2-4-4) Transition from the heating / cooling mixed operation mode to the steady heating operation mode From the heating / cooling / heating mixed operation mode 60c when the outside air temperature is high as shown in FIG. , 23 shift to the steady heating operation mode 60b (FIG. 11) in which heating is performed, the control unit 60 passes the state of the refrigerant circuit shown in FIG. When the setting of the use side unit 21 is switched from cooling to heating, the control unit 60 gradually stops the low-stage compressor 51a, and after the pressure difference around the second four-way switching valve 56 becomes small, The state of the second four-way selector valve 56 is switched. And as shown in FIG. 11, the control part 60 opens the 1st branch unit switching valve 31a, closes the 2nd branch unit switching valve 31b, and makes high-pressure refrigerant | coolant all the use side heat exchangers 21a and 22a. , 23a. The refrigerant evaporated in the heat source side heat exchanger 53 is sucked into the low-stage compressor 51a when the state of the second four-way switching valve 56 is switched.

(2-4-5) Transition of the cooling-dominated mixed heating and cooling operation mode accompanying the outside air temperature change From the cooling-dominated mixed cooling and heating operation mode 60c when the outside air temperature is high as shown in FIG. 7 described above, the outside air temperature has decreased. When the control unit 60 shifts to the cooling / heating mixed operation mode 60c in which the outside air temperature is a low temperature (or medium temperature) shown in FIG. 4 described above, the control unit 60 passes the state of the refrigerant circuit shown in FIG. . When the outside air temperature decreases, the pressure of the high-pressure refrigerant decreases. Therefore, the control unit 60 stops the high-stage compressor 51c when the high-low differential pressure cannot be secured. The state of the first four-way switching valve 55 is switched after the pressure difference around the first four-way switching valve 55 becomes small. By switching the state of the first four-way switching valve 55, the intermediate-pressure refrigerant discharged from the low-stage compressor 51a and flowing into the intermediate-pressure pipe 51b flows from the state where the intermediate-pressure refrigerant flows into the use-side heat exchanger 22a. The pressure refrigerant is switched to a state where the refrigerant flows to the heat source side heat exchanger 53.

(2-4-6) Transition of the heating-dominated mixed heating / cooling operation mode accompanying a change in the outside air temperature From the heating-dominated mixed heating / cooling operation mode 60c when the outside air temperature is high, as shown in FIG. 9, the above-described FIG. When shifting to the heating / cooling / heating mixed operation mode 60c when the outside air temperature is low, the control unit 60 passes the state of the refrigerant circuit shown in FIG. When the pressure of the intermediate pressure refrigerant decreases with a decrease in the outside air temperature, the control unit 60 stops the low-stage compressor 51a when it becomes impossible to ensure a high-low differential pressure. The state of the second four-way switching valve 56 is switched after the pressure difference around the second four-way switching valve 56 becomes small. By switching the state of the second four-way selector valve 56, as shown in FIG. 6, the refrigerant evaporated in the use side heat exchanger 21a flows into the intermediate pressure pipe 51b and is sucked into the high stage compressor 51c. It becomes like this. At this time, the refrigerant evaporated in the heat source side heat exchanger 53 is sucked into the low stage compressor 51a.

(3) Features of the air conditioner (3-1)
This air conditioner employs a configuration in which a low-stage compressor 51a and a high-stage compressor 51c are connected in series. In addition, the intermediate pressure refrigerant discharged from the low-stage compressor 51a and flowing to the intermediate pressure pipe 51b flows to the heat source side heat exchanger 53 in the first state shown in FIG. 4, and the second refrigerant shown in FIG. In the state, the refrigerant circuit is configured and controlled so as to flow to the use side heat exchanger 22a. According to this air conditioner, when the outside air temperature is low and the heat source side heat exchanger 53 does not require high-pressure refrigerant, the four-way switching valves 55 and 56 are set to the first state shown in FIG. Driving efficiency can be improved. Further, as shown in FIG. 7, when the outside air temperature is high, the second usage-side heat exchanger 22a is made to have a small amount of heat while the first and third usage-side heat exchangers 21a and 23a function as evaporators. When it is necessary to function as a radiator with respect to a load, the four-way switching valves 55 and 56 are set to the second state shown in FIG. The operating efficiency of the air conditioner can be improved.

(3-2)
As one of the air-conditioning mixed operation modes 60c, the control unit 60 of the air conditioner functions as the first usage-side heat exchanger 21a as an evaporator and the second usage-side heat exchanger 22a as a radiator. It has an intermediate pressure use operation mode (see FIGS. 4 and 7). In this intermediate pressure use operation mode, the control unit 60 causes the intermediate pressure refrigerant discharged from the low-stage compressor 51a and flowing to the intermediate pressure pipe 51b to the heat source side heat exchanger 53 or the use side heat exchanger 22a. The four-way switching valves 55 and 56 that are switching mechanisms are controlled so as to flow directly. In this way, not only the high-pressure refrigerant discharged from the conventionally used high-stage compressor but also the intermediate-pressure refrigerant is actively used so that the operation of reducing the pressure of the high-pressure refrigerant is not wasted. As a result, the operating efficiency of the air conditioner can be improved.

(3-3)
The control unit 60 of the air conditioner has a first mixed operation mode shown in FIG. 7 and a second mixed operation mode shown in FIG. 4 as the cooling / heating mixed operation mode 60c. Then, the four-way switching valves 55 and 56 are controlled so that the intermediate pressure refrigerant flows in the first mixed operation mode and the high pressure refrigerant flows in the second mixed operation mode with respect to the second usage-side heat exchanger 22a. Yes. Thus, in this air conditioner, in addition to the selection of flowing high-pressure refrigerant to the use-side heat exchanger 22a, it is possible to select selection of flowing intermediate-pressure refrigerant to the use-side heat exchanger 22a. When the heat load of the installation space of the unit 22 is small, the operation efficiency of the air conditioner can be improved by using the intermediate pressure refrigerant.

(3-4)
In the first mixed operation mode shown in FIG. 7, the control unit 60 of the air conditioner flows the high-pressure refrigerant discharged from the high stage compressor 51c to the heat source side heat exchanger 53 to dissipate heat, while the low stage compressor 51a. A part of the intermediate pressure refrigerant discharged from the refrigerant flows through the second usage-side heat exchanger 22a to dissipate heat, so that the second usage-side unit 22 performs the heating operation. The refrigerant radiated and condensed in the heat source side heat exchanger 53 and the use side heat exchanger 22a flows into the first and third use side heat exchangers 21a and 23a and evaporates. The first mixed operation mode is selected by the control unit 60 when the outside air temperature is high and the heating heat load of the second usage-side unit 22 is small, and the operation efficiency of the air conditioner is improved.

(3-5)
In the second mixed operation mode shown in FIG. 4, the controller 60 of the air conditioner is configured so that the high-pressure refrigerant discharged from the high-stage compressor 51c flows to the second usage-side heat exchanger 22a and is low. The four-way switching valves 55 and 56 are controlled so that a part of the intermediate pressure refrigerant discharged from the stage compressor 51a flows to the heat source side heat exchanger 53, and further, the heat source side fan 59 is controlled according to the outside air temperature. The pressure of the intermediate pressure refrigerant is adjusted by changing the rotation speed. Specifically, when the outside air temperature decreases, the control unit 60 performs fan control that increases the pressure of the intermediate pressure refrigerant by reducing the rotation speed of the heat source side fan 59. Thereby, the operating efficiency of the air conditioner is improved.

(3-6)
When switching from the first mixed operation mode shown in FIG. 7 to the second mixed operation mode shown in FIG. 4, the control unit 60 of the air conditioner passes the state of the refrigerant circuit shown in FIG. 12. Specifically, the high stage compressor 51c is temporarily stopped in the switching process, and the state of the first four-way switching valve 55 is changed after the pressure difference around the first four-way switching valve 55 becomes small. Switching. Thus, the noise accompanying the state switching of the four-way switching valve 55 can be suppressed by temporarily stopping the high stage compressor 51c. Further, since the state is switched after the surrounding pressure difference becomes small, the state of the four-way switching valve 55 can be switched reliably.

21, 22, 23 User side units 21a, 22a, 23a User side heat exchangers 21b, 22b, 23b User side expansion valves (user side expansion mechanism)
DESCRIPTION OF SYMBOLS 50 Heat source side unit 51 Compression mechanism 51a Low stage compressor 51b Intermediate pressure piping 51c High stage compressor 53 Heat source side heat exchanger 54 Heat source side expansion valve (Heat source side expansion mechanism)
55, 56 Four-way switching valve (switching mechanism)
59 Heat source side fan 60 Control unit 60c Air-conditioning mixed operation mode 65 Outside air temperature sensor

JP 2003-130492 A

Claims (6)

A heat source side unit (50) having a compression mechanism (51) including a low stage compressor (51a) and a high stage compressor (51c), a heat source side heat exchanger (53), and a heat source side expansion mechanism (54). )When,
A first usage-side unit (21) having a first usage-side heat exchanger (21a) and a first usage-side expansion mechanism (21b);
A second usage side unit (22) having a second usage side heat exchanger (22a) and a second usage side expansion mechanism (22b);
A switching mechanism (55, 56) for switching a path of refrigerant flowing from the compression mechanism to the heat source side heat exchanger, the first usage side heat exchanger, and the second usage side heat exchanger;
With
The low-stage compressor and the high-stage compressor are connected in series via an intermediate pressure pipe (51b),
The switching mechanism (55, 56) includes a first state in which the intermediate pressure refrigerant discharged from the low-stage compressor and flowing to the intermediate pressure pipe flows to the heat source side heat exchanger, and the intermediate pressure refrigerant is The first usage side heat exchanger or the second state flowing to the second usage side heat exchanger switches.
Refrigeration equipment. A control unit (60) for controlling the switching mechanism;
The controller is
The first usage side heat exchanger (21a) functions as an evaporator, and the second usage side heat exchanger (22a) has an intermediate pressure usage operation mode in which it functions as a radiator,
In the intermediate pressure use operation mode, the intermediate pressure refrigerant discharged from the low-stage compressor (51a) and flowing into the intermediate pressure pipe (51b) is converted into the heat source side heat exchanger (53) and the first use side heat. Controlling the switching mechanism (55, 56) so as to flow directly to the exchanger (21a) or the second use side heat exchanger (22a);
The refrigeration apparatus according to claim 1. A control unit (60) for controlling the switching mechanism;
The controller is
The first usage side heat exchanger (21a) functions as an evaporator, and the second usage side heat exchanger (22a) functions as a radiator, and has a first mixed operation mode and a second mixed operation mode,
In the first mixed operation mode, the intermediate pressure refrigerant discharged from the low-stage compressor (51a) and flowing to the intermediate pressure pipe (51b) flows to the second usage side heat exchanger (22a). And controlling the switching mechanism (55, 56),
In the second mixed operation mode, the switching mechanism (55, 56) is set so that the high-pressure refrigerant discharged from the high stage compressor (51c) flows to the second usage side heat exchanger (22a). Control,
The refrigeration apparatus according to claim 1. In the first mixed operation mode, the control unit is configured such that the intermediate pressure refrigerant flows into the second usage side heat exchanger (22a) and is discharged from the high stage compressor (51c). Controlling the switching mechanism (55, 56) so that the refrigerant flows to the heat source side heat exchanger (53);
The refrigeration apparatus according to claim 3. The heat source side unit (50) further includes a heat source side fan (59) for sending outside air to the heat source side heat exchanger (53), and an outside air temperature sensor (65) for detecting outside air temperature,
In the second mixed operation mode, the control unit is configured such that the high-pressure refrigerant flows to the second usage-side heat exchanger (22a) and the intermediate-pressure refrigerant is the heat source side heat exchanger (53). The switching mechanism (55, 56) is controlled so as to flow to the side, and the rotation speed of the heat source side fan is changed according to the outside air temperature to adjust the pressure of the intermediate pressure refrigerant.
The refrigeration apparatus according to claim 3 or 4. When the control unit switches from the first mixed operation mode to the second mixed operation mode, the control unit temporarily stops the low-stage compressor (51a) or the high-stage compressor (51c), and the switching mechanism ( 55, 56), after switching the refrigerant path, return to the state where both the low-stage compressor (51a) and the high-stage compressor (51c) are operated.
The refrigeration apparatus according to any one of claims 3 to 5.

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