WO2008013092A1

WO2008013092A1 - Heat source unit and air conditioner with the same

Info

Publication number: WO2008013092A1
Application number: PCT/JP2007/064234
Authority: WO
Inventors: Hiromune Matsuoka
Original assignee: Daikin Industries, Ltd.
Priority date: 2006-07-24
Filing date: 2007-07-19
Publication date: 2008-01-31
Also published as: JP2008025939A

Abstract

A heat source unit having sealed compressors and forming an air conditioner using carbon dioxide as the refrigerant. The heat source unit (2) forms a refrigerant circuit (10) using the carbon dioxide as the refrigerant, and utilization units (4, 5) are connected to the heat source unit (2). The heat source unit (2) has the sealed compressors (21, 22) each having, installed in a casing (61), a compression element (62) and a compressor motor (63) for driving the compression element (62), polyalkylene glycol as a refrigeration machine oil, and an electric current cancellation device (95) for canceling a leakage current from the compressor motor (63).

Description

Specification

Heat source unit and air conditioner equipped with the same

Technical field

The present invention relates to a heat source unit and an air conditioner including the heat source unit, and in particular, to a heat source unit that forms a refrigerant circuit that uses carbon dioxide as a refrigerant by connecting a utilization unit and the same. The present invention relates to an air conditioner.

Background art

[0002] In a so-called separate type air conditioner in which a refrigerant circuit is configured by connecting a utilization unit and a heat source unit, CFC-based refrigerant, HCFC-based refrigerant, HFC are used as the refrigerant enclosed in the refrigerant circuit. System refrigerant is used. However, from the viewpoint of environmental problems, the use of natural refrigerants that have a small impact on the environment is also being considered for separate air conditioners, especially non-combustible and non-toxic carbon dioxide. Promising to use.

Disclosure of the invention

[0003] In the above-described separate type air conditioner, when carbon dioxide is used as a refrigerant, a high-viscosity refrigerating machine oil is used to ensure lubrication in the compressor because the refrigeration cycle has a high pressure. A refrigerating machine oil suitable for this is polyalkylene glycolenoles (hereinafter referred to as PAG).

On the other hand, since PAG is highly conductive, if the compressor built in the heat source unit is a hermetic compressor, the leakage current increases and is unsuitable. However, when carbon dioxide is used as the refrigerant. Therefore, it is desirable to use a hermetic compressor because the high pressure in the refrigeration cycle requires sealing performance in the compressor.

If the PAG is used as refrigeration oil in a heat source unit with a built-in hermetic compressor, focusing on ensuring lubrication and sealing performance in the compressor, the leakage current from the motor built in the compressor will increase. The problem of becoming will arise. In particular, when configuring a large-capacity heat source unit that assumes that multiple units are connected, multiple compressors are built in the unit, so leakage current with motor power Excessive The driving itself may become difficult. For this reason, it is difficult to realize a heat source unit that includes a plurality of hermetic compressors and constitutes an air conditioner that uses carbon dioxide as a refrigerant.

An object of the present invention is to realize a heat source unit that constitutes an air conditioner that includes a plurality of hermetic compressors and uses carbon dioxide as a refrigerant.

[0004] A heat source unit according to a first aspect of the present invention is a heat source unit that constitutes a refrigerant circuit that uses carbon dioxide and carbon dioxide as a refrigerant by connecting a utilization unit. And a plurality of hermetic compressors in which a motor for driving the compression element is arranged, polyalkylene glycol as refrigeration oil, and a current canceling device that cancels leakage current from the motor.

In this heat source unit, in the case of using carbon dioxide as a refrigerant, polyalkylene glycol (hereinafter referred to as PAG) is used as a refrigerating machine oil to ensure lubrication in the compressor, and a plurality of compression By using a hermetic compressor as a compressor, the sealing performance inside the compressor can be secured, and an increase in leakage current from the motor can be suppressed by providing a current canceling device. Thus, a heat source unit that includes a plurality of hermetic compressors and constitutes an air conditioner that uses carbon dioxide as a refrigerant can be realized.

[0005] The heat source unit according to the second invention is the heat source unit of the air conditioner according to the first invention, wherein an oil reservoir portion for storing refrigerator oil is formed in the casing. Yes. The motor is arranged so that there is no immersion force in the refrigerating machine oil collected in the oil reservoir. In this heat source unit, since the motor is arranged so that there is no immersion force in the refrigeration machine oil accumulated in the oil reservoir, an increase in leakage current from the motor can be further suppressed.

[0006] A heat source unit according to the third aspect of the present invention is the heat source unit of the air conditioner according to the second aspect of the present invention, wherein the motor is disposed above the compression element.

In this heat source unit, since the motor is arranged above the compression element, it is possible to further suppress an increase in leakage current due to the motor power.

[0007] A heat source unit according to a fourth aspect of the present invention is the heat source unit of an air conditioner according to any of the first to third aspects of the invention, wherein the compression element is a cylinder having a cylinder chamber formed therein. And a piston formed by a roller and a blade formed integrally with the roller. The piston divides the cylinder chamber into a suction chamber and a discharge chamber, and a bush sandwiching the blade. The piston is revolved in the cylinder chamber by a motor. It is configured to exercise.

In this heat source unit, the compression element constitutes a so-called swing compressor having a cylinder, a piston in which a roller and a blade are integrally formed, and a bush. For this reason, this compression element is suitable for incorporating a plurality of small compressors in a unit in which friction loss and power loss are relatively small compared to other types of positive displacement compression elements. On the other hand, in this compression element, the roller and the blade are integrally formed, and this is due to the high pressure caused by the use of carbon dioxide with a large sliding between the piston and the bush as the refrigerant. Therefore, problems such as an increase in sliding load between the piston and the bush and seizure tend to occur. However, in this heat source unit, PAG is used as refrigeration oil, so that sufficient lubrication between the piston and bushing can be secured, so multiple compressors can be unitized by adopting a swing compressor. While facilitating the incorporation into the inside, it is possible to suppress the occurrence of problems such as an increase in the sliding load between the piston and the bush and the occurrence of seizure, which are feared by the adoption of the swing compressor.

[0008] A heat source unit according to a fifth aspect of the present invention is the heat source unit of the air conditioner according to any of the first to fourth aspects of the present invention, further comprising an inverter device for controlling the motor, and a current canceling device. Cancels the high-frequency leakage current caused by the inverter device. Since this heat source unit is controlled by the motor force S inverter device built in the hermetic compressor, high frequency leakage current is generated due to the voltage output to this inverter device force motor. . For this reason, when a plurality of hermetic compressors are provided as in this heat source unit, the leakage current from the motor increases remarkably. However, since this heat source unit includes a current cancellation device, an increase in leakage current due to the high-frequency leakage current can be suppressed. As a result, a plurality of hermetic compressors with built-in motors controlled by the inverter device are provided, and a heat source unit that constitutes an air conditioner that uses carbon dioxide as a refrigerant can be realized. .

[0009] An air conditioner according to a sixth invention includes the heat source unit according to any one of the first to fifth inventions. Since this air conditioner includes the heat source unit according to any of the first to fifth inventions, a large-capacity refrigerant that uses carbon dioxide as a refrigerant by connecting a plurality of utilization units. A circuit can be constructed.

Brief Description of Drawings

FIG. 1 is a schematic configuration diagram of a heat source unit and an air conditioner equipped with the heat source unit according to an embodiment of the present invention.

FIG. 2 is a schematic longitudinal sectional view of a compressor.

FIG. 3 is a schematic cross-sectional view of the compressor, corresponding to the AA cross section of FIG.

4 is a schematic cross-sectional view of the compressor, corresponding to the BB cross section of FIG.

FIG. 5 is a control block diagram of the air conditioner.

FIG. 6 is a schematic electric circuit diagram of an inverter device including a current canceling device.

FIG. 7 is a modification of the schematic electric circuit diagram of the inverter device including the current canceling device.

FIG. 8 is a modification of the schematic electric circuit diagram of the inverter device including the current canceling device. Explanation of symbols

[0011] 1 Air conditioner

2 Heat source unit

4, 5 Usage unit

10 Refrigerant circuit

21, 22 Compressor (closed compressor)

61 Casing

61d Oil reservoir

62 compression elements

63 Compressor motor (motor)

70, 73 Pissun

70a, 73a roller

70b, 73b blade

71, 74 bush

72, 75 cylinders 76, 77 Cylinder chamber

76a, 77a Suction chamber

76b, 77b Discharge chamber

91 Inverter device

95 Current canceling device

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of a heat source unit according to the present invention and an air conditioner including the heat source unit will be described with reference to the drawings.

(1) Configuration of air conditioner

FIG. 1 is a schematic configuration diagram of a heat source unit and an air-conditioning apparatus 1 including the heat source unit according to an embodiment of the present invention. In the present embodiment, the air conditioner 1 is an apparatus used for indoor cooling, and mainly includes one heat source unit 2, a plurality (two in this case) of utilization units 4 and 5, and a heat source. This is a so-called multi-type air conditioner including refrigerant communication pipes 6 and 7 that connect the unit 2 and the utilization units 4 and 5. The refrigerant circuit 10 of the air conditioner 1 of the present embodiment is configured by connecting the heat source unit 2 and the utilization units 4 and 5 via the refrigerant communication tubes 6 and 7. In the refrigerant circuit 10, carbon dioxide is sealed as a refrigerant. For this reason, in the air conditioning apparatus 1 of the present embodiment, the refrigeration cycle operation is performed by compressing the carbon dioxide as a cooling medium until the critical pressure or higher is reached.

[0013] <Usage unit>

The utilization units 4 and 5 are connected to the heat source unit 2 via the refrigerant communication pipe 6 and the refrigerant communication pipe 7 and constitute a part of the refrigerant circuit 10.

Next, the configuration of the usage units 4 and 5 will be described. Since the usage unit 4 and the usage unit 5 have the same configuration, only the configuration of the usage unit 4 will be described here, and the configuration of the usage unit 5 indicates each part of the usage unit 4. Instead of the 40's code, the 50's code is used, and the description of each part is omitted.

The usage unit 4 mainly includes a usage-side refrigerant circuit 10b that constitutes a part of the refrigerant circuit 10. Have. The use side refrigerant circuit 10b mainly includes a use side expansion mechanism 41 that depressurizes the refrigerant, and a use side heat exchange 42.

[0014] In the present embodiment, the use side expansion mechanism 41 is an electric expansion valve that adjusts the flow rate of the refrigerant flowing in the use side refrigerant circuit 10b, one end of which is connected to the refrigerant communication pipe 6, The end is connected to the heat exchanger 42 on the user side.

In the present embodiment, the use-side heat exchanger 42 is a heat exchanger that functions as a refrigerant heater. One end of the use side heat exchanger 42 is connected to the refrigerant communication pipe 7, and the other end is connected to the use side expansion mechanism 41.

In the present embodiment, the usage unit 4 includes an indoor fan 43 for sucking indoor air into the unit, exchanging heat, and supplying the indoor air to the room, and a refrigerant flowing between the indoor air and the usage-side heat exchanger. It is possible to exchange heat. The indoor fan 43 is rotationally driven by a fan motor 43a.

In addition, the usage unit 4 includes a usage-side control unit 44 that controls the operation of each unit constituting the usage unit 4. The usage-side control unit 44 includes a microcomputer, a memory, and the like provided for controlling the usage unit 4, and a remote controller (not shown) for operating the usage unit 4 individually. Control signals and the like can be exchanged between them, and control signals and the like can be exchanged with the heat source side control unit 28 (described later) of the heat source unit 2.

The heat source unit 2 is connected to the usage units 4 and 5 via the refrigerant communication pipe 6 and the refrigerant communication pipe 7, and a refrigerant circuit 10 is configured between the usage units 4 and 5.

Next, the configuration of the heat source unit 2 will be described. The heat source unit 2 mainly has a heat source side refrigerant circuit 10 a that constitutes a part of the refrigerant circuit 10. The heat source side refrigerant circuit 10a mainly includes a plurality of (here, two) compressors 21 and 22, a heat source side heat exchange 23, and a heat source side expansion mechanism 24 as an expansion mechanism that depressurizes the refrigerant. , With shut-off valves 25, 26

In the present embodiment, the heat source side heat exchanger 23 is a heat exchanger that functions as a refrigerant cooler. One end of the heat source side heat exchanger 23 is connected to the discharge side of the compressors 21 and 22. The other end is connected to the heat source side expansion mechanism 24.

In the present embodiment, the heat source side expansion mechanism 24 is an electric expansion valve, one end of which is connected to the other end of the heat source side heat exchange, and the other end is connected to the closing valve 25.

In this embodiment, the heat source unit 2 includes an outdoor fan 27 for sucking outdoor air into the unit, exchanging heat, and then discharging the air to the outside, and flows through the heat exchange 23 on the heat source side with the outdoor air. It is possible to exchange heat with the refrigerant. The outdoor fan 27 is rotationally driven by a fan motor 27a.

The shut-off valves 25 and 26 are valves provided at connection ports with external equipment 'piping (specifically, refrigerant communication pipes 6 and 7). The closing valve 25 is connected to the heat source side expansion mechanism 24. The shut-off valve 26 is connected to the suction side of the compressors 21 and 22.

The compressors 21 and 22 are compressors for compressing a low-pressure gas refrigerant to a critical pressure (the critical pressure of carbon dioxide is 7.38 MPa) or higher. In the present embodiment, the force provided by the two compressors 21 and 22 in the heat source unit 2 is not limited to this. Three or more units are used depending on the number of connected units, etc. The compressor may be connected in parallel. Next, the configuration of the compressors 21 and 22 will be described with reference to FIGS. Note that since the compressor 21 and the compressor 22 have the same configuration, only the configuration of the compressor 21 will be described here, and the configuration of the compressor 22 will be denoted by a reference numeral indicating each part of the compressor 22, respectively. The description of each part is abbreviate | omitted as the same code | symbol is attached | subjected. Here, FIG. 2 is a schematic longitudinal sectional view of the compressor 21. FIG. 3 is a schematic transverse cross-sectional view of the compressor 21, and corresponds to the AA cross section of FIG. FIG. 4 is a schematic cross-sectional view of the compressor 21, which corresponds to the BB cross section of FIG.

[0018] In the present embodiment, the compressor 21 is a hermetic compressor in which a compression element 62 and a compressor motor 63 are incorporated in a casing 61 that is a vertical cylindrical container.

The casing 61 includes a substantially cylindrical body plate 61a, an upper end plate 61b welded and fixed to the upper end of the body plate 61a, and a lower end plate 61c fixed to the lower end of the body plate 61a by welding. And in this casing 61, the compression element 62 is mainly arrange | positioned at the lower part, and the compressor motor 63 is arrange | positioned above the compression element. The compression element 62 and the compressor motor 63 are connected by a crankshaft 64 arranged so as to extend in the vertical direction in the casing 61. It is. In the present embodiment, an oil reservoir 61d is formed in the lower part of the casing 61 for storing the refrigerating machine oil necessary for lubricating the compressor 21 (particularly, the compression element 62). As a refrigerating machine oil, polyalkylene glycol (hereinafter referred to as PAG) having a high viscosity characteristic is used in consideration of using carbon dioxide as a refrigerant.

The compression element 62 is a compression element that constitutes a swing compressor. In the present embodiment, the compression element 62 mainly includes a crankshaft 64, a front head 65, a first compression element 66, an intermediate head 67, and a second head. A compression element 68 and a rear head 69 are included. Here, the first compression element 66 is disposed so as to be sandwiched between the front head 65 and the intermediate head 67 in the vertical direction, and mainly includes the first piston 70, the first bush 71, and the first cylinder 72. It consists of and. The second compression element 68 is disposed so as to be sandwiched between the intermediate head 67 and the rear head 69 in the vertical direction, and mainly includes the second piston 73, the second bush 74, and the second cylinder 75. They are organized. In the present embodiment, the front head 65, the first cylinder 72, the intermediate head 67, the second cylinder 75, and the rear head 69 are fastened together by a plurality of bolts (not shown) and joined together. In this embodiment, the compression element constituting the swing compressor is selected as the compression element 62 because the friction loss and the power loss are relatively small compared to other types of positive displacement compression elements. It is also suitable for incorporating multiple small compressors (here, two compressors 21 and 22).

[0020] The first cylinder 72 has a cylinder hole 72a, a suction hole 72b, a discharge passage 72c, and a blade accommodation hole 72d. The cylinder hole 72a is a cylindrical hole penetrating along the rotation axis O. The suction hole 72b penetrates from the outer peripheral surface 72e to the cylinder hole 72a. The discharge path 72c is formed by cutting out a part of the inner peripheral side of the cylindrical portion forming the cylinder hole 72a. The blade accommodation hole 72d is a hole for accommodating a blade portion 70b (described later) of the first piston 70, and penetrates along the thickness direction of the first cylinder 72. The portion of the blade accommodation hole 72d on the rotation axis O side accommodates the first bush 71 and slides with the first bush 71. A first eccentric shaft portion 64a of the crankshaft 64 and a roller 70a (described later) of the first piston 70 are accommodated in the cylinder hole 72a of the first cylinder 72, and the first eccentric shaft portion 64a is accommodated in the blade accommodation hole 72d. The state where the blade portion 70b of the piston 70 and the first bush 71 are accommodated. Thus, the discharge path 72c is sandwiched between the front head 65 and the intermediate head 67 so as to face the front head 65 side. Thus, a cylinder chamber 76 is formed in the first compression element 62. The cylinder chamber 76 includes a suction chamber 76a that communicates with the suction hole 72b by the first piston 70, and a discharge chamber 76b that communicates with the discharge passage 72c. It will be divided into.

[0021] The first piston 70 has a cylindrical roller 70a and a blade 70b that is formed integrally with the roller 70a and protrudes radially outward of the roller 70a. The roller 70 a is inserted into the cylinder hole 72 a of the first cylinder 72 in a state of being fitted to the first eccentric shaft portion 64 a of the crank shaft 64. As a result, when the crankshaft 64 rotates, the roller 70a performs a revolving motion around the rotation axis O of the crankshaft 64. The blade 70b is accommodated in the blade accommodation hole 72d. As a result, the blade 70b swings and moves forward and backward along the longitudinal direction with respect to the first bush 71 and the blade accommodation hole 72d.

The first bush 71 is a pair of substantially semi-cylindrical members, and is accommodated in the blade accommodation hole 72d so as to sandwich the blade 7 Ob of the first piston 70.

The front head 65 is a member that covers the discharge path 72c side of the first cylinder 72, and is fitted to the casing 61. The front head 65 is formed with a bearing portion 65a, and a crankshaft 64 is inserted into the bearing portion 65a. Further, the front head 65 is formed with an opening 65b for guiding the gas refrigerant flowing through the discharge passage 72c formed in the first cylinder 72 to a discharge pipe 85 (described later). The opening 65b is closed or opened by a discharge valve (not shown) for preventing the backflow of the gas refrigerant.

The intermediate head 67 is a member that faces the front head 65 with the first cylinder 72 interposed therebetween, and covers the lower portion of the first cylinder 72. The intermediate head 67 is formed with a bearing portion 67a, and a crankshaft 64 is inserted into the bearing portion 67a.

[0023] Similar to the first cylinder 72, the second cylinder 75 has a cylinder hole 75a, a suction hole 75b, a discharge passage 75c, and a blade accommodation hole 75d. The cylinder hole 75a is a cylindrical hole penetrating along the rotation axis O. The suction hole 75b extends from the outer peripheral surface 75e to the cylinder hole 75a. The discharge path 75c is a part of the inner peripheral side of the cylindrical part that forms the cylinder hole 75a. Is formed by notching. The blade accommodation hole 75d is a hole for accommodating a blade portion 73b (described later) of the second piston 73, and penetrates along the thickness direction of the second cylinder 75. The portion on the rotation axis O side of the blade accommodation hole 75d accommodates the second bush 74 and slides with the second bush 74. A second eccentric shaft portion 64b of the crankshaft 64 and a roller 73a (described later) of the second piston 73 are accommodated in the cylinder hole 75a of the second cylinder 75, and the second piston is accommodated in the blade accommodation hole 75d. In a state where the blade portion 73b and the second bush 74 of 73 are accommodated, the discharge path 75c is sandwiched between the rear head 69 and the intermediate head 67 so that the discharge path 75c faces the rear head 69 side. As a result, a cylinder chamber 77 is formed in the second compression element 68. The cylinder chamber 77 is connected to a suction chamber 77a that communicates with the suction hole 75b by the second piston 73, and a discharge chamber 77b that communicates with the discharge passage 75c. It will be divided into. The second eccentric shaft portion 64b and the first eccentric shaft portion 64a are provided with a phase difference of 180 degrees.

[0024] Like the first piston 70, the second piston 73 has a cylindrical roller 73a and a blade 73b that is formed integrally with the roller 73a and protrudes radially outward of the roller 73a. Yes. The roller 73a is inserted into the cylinder hole 75a of the second cylinder 75 while being fitted to the second eccentric shaft portion 64b of the crankshaft 64. As a result, when the crankshaft 64 rotates, the roller 73a performs a revolving motion around the rotation axis O of the crankshaft 64. The blade 73b is accommodated in the blade accommodation hole 75d. As a result, the blade 73b swings and simultaneously moves forward and backward with respect to the second bush 74 and the blade accommodation hole 75d along the longitudinal direction. Since the second eccentric shaft portion 64b and the first eccentric shaft portion 64a are 180 degrees out of phase as described above, for example, the blade 70b of the first piston 70 is inserted into the blade receiving hole of the first cylinder 72. When the blade 72b is inserted into the deepest position 72d, the blade 73b of the second piston 73 is inserted into the blade receiving hole 75d of the second cylinder 75 at the shallowest depth.

Similarly to the first bush 71, the second bush 74 is a pair of substantially semi-cylindrical members, and is accommodated in the blade accommodation hole 75d so as to sandwich the blade 73b of the second piston 73. 69 is a member that covers the discharge path 75c side of the second cylinder 75, and is fitted in the casing 61. The rear head 69 is formed with a bearing portion 69a. A crankshaft 64 is inserted into 9a. Further, the rear head 69 is formed with an opening 69b for guiding the gas refrigerant flowing in through the discharge passage 75c formed in the second cylinder 75 to a discharge pipe 85 (described later). The opening 69b is closed or opened by a discharge valve (not shown) for preventing the backflow of the gas refrigerant.

The crankshaft 64 is provided with the above-described eccentric shaft portions 64a and 64b at the lower portion thereof, and the upper portion where the eccentric shaft portions 64a and 64b are not provided is the rotor 80 ( (Described later). The crankshaft 64 is formed with an oil passage 64c that opens to the oil reservoir 61d and communicates with the cylinder chambers 76 and 77. A pump element 78 is provided at the lower end of the oil passage 64c. The pump element 78 supplies the cylinder chambers 76 and 77 via the oil passage 64c accumulated in the oil reservoir 61d.

In this embodiment, the compressor motor 63 is a direct current motor, and is mainly housed in an annular stator 79 fixed to the inner surface of the casing 61 and rotatably inside the stator 79 with a slight gap therebetween. It consists of a rotor 80. A copper wire is wound around the stator 79, and a coil end 79a is formed above and below. A crankshaft 64 is fixed at the center of the rotor 80 along the rotation axis O. The copper wire wound around the stator 79 of the compressor motor 63 is connected to a terminal 86 provided on the casing 61 and supplied with power. The casing 61 is grounded to an earth E (see FIGS. 6, 7 and 8) not shown in FIGS.

In addition, the casing 61 is provided with first and second suction pipes 81 and 82 so as to penetrate the body plate 61a. One end of the first suction pipe 81 communicates with the suction hole 72b of the first cylinder 72, and the other end communicates with an accumulator 83 attached to the outside of the casing 61. One end of the second suction pipe 82 communicates with the suction hole 75 b of the second cylinder 75, and the other end communicates with an accumulator 83 attached to the outside of the casing 61. The accumulator 83 is provided with a suction pipe 84. Further, the casing 61 is provided with a discharge pipe 85 so as to penetrate the upper end plate 61b.

As described above, the compressors 21 and 22 are two-cylinder hermetic swing compressors having the two compression elements 66 and 68 constituting the swing compressor in the present embodiment. Then, in the compressors 21 and 22, the piston motors 63 and 68 are fixed by the compressor motor 63. 70, 73 (more specifically, rollers 70a, 73a) revolves in the cylinder chambers 76, 77, the low-pressure gas refrigerant passes through the suction pipe 84, the accumulator 83, and the suction pipes 81, 82. Then, the suction force 72b, 75b force flows into the cylinder chambers 76, 77 and is compressed by the rollers 70a, 73a. Then, the high-pressure gas refrigerant compressed by the roller 70a of the first compression element 66 passes from the opening 65b of the front head 65 to the space inside the casing 61 outside the compression element 62 via the discharge path 72c of the first cylinder 72. Discharged. Further, the high-pressure gas refrigerant compressed by the inlet 73a of the second compression element 68 passes through the discharge passage 75c of the second cylinder 75 and opens in the space in the casing 61 outside the compression element 62 from the opening 69b of the rear head 69. Discharged. Further, the high-pressure gas refrigerant discharged from the first compression element 66 to the space in the casing 61 outside the compression element 62 and the second compression element 68 to the space in the casing 61 outside the compression element 62 were discharged. The high-pressure gas refrigerant merges into the space in the casing 61 and is discharged from the discharge pipe 85.

The heat source unit 2 includes a heat source side control unit 28 that controls the operation of each unit constituting the heat source unit 2. The heat source side control unit 28 includes a microcomputer, a memory, and the like provided for controlling the heat source unit 2, and transmits data to and from the usage side control units 44 and 54 of the usage units 4 and 5. Control signals etc. can be exchanged via the line 8a. In other words, the use side control units 44 and 54 and the heat source side control unit 28 constitute a control unit 8 as operation control means for performing operation control of the air conditioner 1. As shown in FIG. 5, the control unit 8 is connected so as to control various devices and valves 21, 22, 27, 43, 53. Here, FIG. 5 is a control block diagram of the air-conditioning apparatus 1 according to the present embodiment.

In the present embodiment, the compressor motor 63 of each of the compressors 21 and 22 is controlled by an inverter device 91 as shown in FIG. Therefore, the operating capacity of both the compressors 21 and 22 can be varied.

Next, the inverter device 91 will be described with reference to FIG. Here, FIG. 6 is a schematic electric circuit diagram of an inverter device 91 including a current canceling device 95 (described later).

The inverter device 91 mainly includes a rectifier circuit 92 and a switching circuit 93 connected to the output side of the rectifier circuit 92. The rectifier circuit 92 is connected to an AC power source 94. It has the function of converting the AC voltage of the AC power supply 94 to DC voltage. The switching circuit 93 has a function of converting the DC voltage supplied from the rectifier circuit 92 into a three-phase high-frequency voltage and outputting it to the compressor motor 63.

On the other hand, the casing 61 of each compressor 21 and 22 is connected to the ground E, and there is a stray capacity C between the compressor motor 63 and the casing 61. During operation of the compressors 21 and 22, A zero-phase voltage is generated through the stray capacitance C, and a high-frequency leakage current il flows from the stray capacitance C to the ground E. This high-frequency leakage current il varies depending on the conductivity of the refrigerant in the compressors 21 and 22 and the refrigerating machine oil. For this reason, when the PAG is used as a refrigerating machine oil as in this embodiment, the high-frequency leakage current il tends to increase.

[0030] Therefore, in the inverter device 91, in order to suppress an increase in the leakage current from the compressor motor 63 due to such a high-frequency leakage current il, a current cancellation device 95 and a leakage current signal are provided. A detector 96 is further provided. The leakage current signal detector 96 is for detecting the high frequency leakage current il, and is provided between the AC power supply 94 and the rectifier circuit 92 in FIG. The current cancellation device 95 is an amplifier circuit that generates a cancellation current i2 having a waveform similar to the high-frequency leakage current il detected by the leakage current signal detector 96. The cancellation current i2 is converted into a rectifier circuit 92 and a switching circuit 93. It has a function to output during Since this current canceling device 95 is also connected to the ground E, as a result, the canceling current i2 is canceled out from the high-frequency leakage current il, and the leakage current i3 flowing through the stray capacitance C force ground E is reduced. can do. As shown in FIG. 6, the leakage current signal detector 96 is provided between the AC power supply 94 and the rectifier circuit 92, and as shown in FIG. 7, the switching circuit 93 and the compressor motor 63 Or between the rectifier circuit 92 and the switching circuit 93 as shown in FIG. Here, FIG. 7 and FIG. 8 are modifications of the schematic electric circuit diagram of the inverter device including the current cancellation device 95.

[0031] <Refrigerant tube>

Refrigerant communication pipes 6 and 7 are refrigerant pipes installed on site when the air conditioner 1 is installed at the installation site.

As described above, the use-side refrigerant circuits 10b and 10c and the plural (here, two) compressors 21 and 2 The refrigerant circuit 10a of the air conditioner 1 using the heat source side refrigerant circuit 10a having 2 and the refrigerant communication pipes 6 and 7 as the refrigerant and using PAG as the refrigerating machine oil is configured. Has been. The air conditioner 1 of the present embodiment includes each of the heat source unit 2 and the usage units 4 and 5 by the control unit 8 including the usage side control units 44 and 54, the heat source side control unit 28, and the transmission line 8a. Control the equipment to perform the cooling operation, that is, the refrigeration cycle operation in which the heat source side heat exchange 23 functions as a refrigerant cooler and the use side heat exchange 42, 52 functions as a refrigerant heater. Now that you can!

[0032] (2) Operation of the air conditioner

Next, the operation of the air conditioner 1 of the present embodiment will be described.

First, when the shut-off valves 25 and 26 are fully opened and an operation command is issued from the remote control, etc., the compressor motor 63 of the compressors 21 and 22, the fan motor 27a of the outdoor fan 27, the fan motor 43a of the indoor fans 43 and 53, 53a is activated. Then, the low-pressure gas refrigerant is sucked into the compressors 21 and 22 and compressed until the pressure becomes equal to or higher than the critical pressure, and becomes a high-pressure gas refrigerant.

After that, the high-pressure gas refrigerant discharged from the compressors 21 and 22 is merged and then sent to the heat source side heat exchanger 23, where it is cooled by exchanging heat with the outdoor air supplied by the outdoor fan 27. The Then, the high-pressure refrigerant cooled in the heat source side heat exchanger 23 is sent to the utilization units 4 and 5 via the heat source side expansion mechanism 24, the closing valve 25 and the refrigerant communication pipe 6. The high-pressure refrigerant sent to the utilization units 4 and 5 is depressurized by the utilization-side expansion mechanisms 41 and 51 to near the suction pressure of the compressor 21 (that is, the pressure of the low-pressure gas refrigerant described above). After being converted to a low-pressure gas-liquid two-phase refrigerant, the refrigerant is sent to each use-side heat exchanger 42, 52, where it is heated and evaporated by exchanging heat with room air in each use-side heat exchanger 42, 52. Thus, it becomes a low-pressure gas refrigerant. The low-pressure gas refrigerant is sent to the heat source unit 2 through the refrigerant communication pipe 7 and is again sucked into the compressors 21 and 22 through the closing valve 26.

[0033] <Compressor operation>

Next, the operation of the compressors 21 and 22 during the above operation will be described in detail. In the compressors 21 and 22, the pistons 70 and 73 (more specifically, rollers 70a and 73a) of the compression elements 66 and 68 are revolving in the cylinder chambers 76 and 77 by the compressor motor 63. Therefore, the low-pressure gas refrigerant flowing into the cylinder chambers 76 and 77 from the suction holes 72b and 75b through the suction pipe 84, the accumulator 83 and the suction pipes 81 and 82 is compressed by the rollers 70a and 73a. Has been. Then, the high-pressure gas refrigerant compressed by the roller 70a of the first compression element 66 passes through the discharge path 72c of the first cylinder 72 and passes through the opening 65b of the front head 65 to the space in the casing 61 outside the compression element 62. Has been discharged. In addition, the high-pressure gas refrigerant compressed by the roller 73a of the second compression element 68 passes through the discharge path 75c of the second cylinder 75 and opens from the opening 69b of the rear head 69 in the casing 61 outside the compression element 62. It is discharged in the middle. Further, the high-pressure gas refrigerant discharged from the first compression element 66 into the space inside the casing 61 outside the compression element 62 and the high-pressure gas refrigerant discharged from the second compression element 68 into the space inside the casing 61 outside the compression element 62. This gas refrigerant joins the air in the casing 61 and is discharged from the discharge pipe 85.

At this time, the temperature at which the temperature of the refrigerant also rises as it is compressed. As in this embodiment, when carbon dioxide is used as the refrigerant, a CFC refrigerant, an HCFC refrigerant, or an HFC refrigerant is used. Since the difference between the suction pressure and the discharge pressure is larger than that, the degree of the temperature rise is also large, and not only the discharge pressure but also the discharge temperature becomes high. On the other hand, in the swing compressors employed as the compressors 21 and 22 of the present embodiment, since the piston formed integrally with the roller and the blade is used as the compression element, the first piston 70 ( More specifically, carbon dioxide having a large sliding between the blade 70b) and the first bush 71 and between the second piston 73 (more specifically, the blade 73b) and the second bush 74 is used as the refrigerant. Due to the increased pressure due to the use, the problems such as increased sliding load and seizure between the piston and bushing tend to occur. However, in this embodiment, PAG having a high viscosity at high temperature is used as refrigeration oil, and the pump element 78 passes through the oil passage 64c from the oil reservoir 61d at the lower part of the casing 61 to the cylinder chambers 76 and 77. Just by supplying refrigeration oil to the first piston 70 (more specifically, the blade 70b) and the first bush 71 and the second piston 73 (more specifically, the blade). 73b) and the second bushing 74 can be lubricated, and problems such as increased sliding load and seizure between the piston and bushing, which are a concern due to the use of a swing compressor, occur. It is now possible to suppress! [0035] However, in the present embodiment, the use of PAG as the refrigerating machine oil has the advantage that lubrication in the compressors 21 and 22 can be ensured, but the conductivity of the PAG is high. As shown in the figure, it has a plurality of hermetic compressors 21 and 22, and the compressor motor 63 built in each compressor 21 and 22 is controlled by an inverter device 91, respectively. The high-frequency leakage current il due to the high-frequency voltage output from the inverter device 91 to the compressor motor 63 tends to increase.

For this reason, in the heat source unit 2 of the present embodiment, the inverter device 91 is provided with the current canceling device 95, and the high-frequency leakage current il that flows toward the ground E also tends to increase the stray capacitance C force. Regardless, ultimately, the leakage current i3 leaking from the ground E force is prevented from increasing.

[0036] Thus, in the present embodiment, the use of PAG as the refrigerating machine oil ensures lubrication in the compressors 21 and 22, and the plurality of compressors 21 and 22 uses a hermetic compressor. As a result, the sealing performance in the compressors 21 and 22 can be secured, and the increase of the leakage current i3 from the compressor motor 63 can be suppressed by providing the current canceling device 95. In this embodiment, the compressor motor 63 is arranged so that the compressor motor 63 is not immersed in the refrigeration oil accumulated in the oil reservoir 61d in the casing 61, and the compressor motor 63 is also compressed by the compression element 62. Since the high frequency leakage current il itself can be reduced, the increase in the leakage current i3 from the compressor motor 63 can be further suppressed.

(3) Features of the air conditioner

The air conditioner 1 of the present embodiment has the following features.

[0037] (A)

In the heat source unit 2 of the present embodiment, in the case where carbon dioxide is used as a refrigerant, lubrication in the compressors 21 and 22 is ensured by using PAG as refrigeration oil, and a plurality of compressors 21 By using a hermetic compressor as 22, the sealing performance in the compressors 21 and 22 is secured, and the current canceling device 95 is provided to suppress the increase in leakage current i3 from the compressor motor 63. Can do. This realizes a heat source unit that has multiple hermetic compressors and constitutes an air conditioner that uses carbon dioxide as a refrigerant. You can do it! /

Since the air conditioner 1 of the present embodiment includes the heat source unit 2 as described above, by connecting a plurality of utilization units 4 and 5, a large capacity that uses carbon dioxide as a refrigerant. The refrigerant circuit 10 can be configured.

[0038] (B)

In the heat source unit 2 of the present embodiment, the compressor motor 63 is arranged so that there is no immersion force in the refrigeration machine oil accumulated in the oil reservoir 6 Id. Because it is arranged on the upper side, the increase in leakage current due to the compressor motor power can be further suppressed! /.

(C)

In the heat source unit 2 of the present embodiment, the compression element 62 includes cylinders 72 and 75, rollers 70a and 73a, blades 70b and 73b, pistons 70 and 73 formed in a force body, and bushes 71 and 74. This constitutes a so-called swing compressor. For this reason, this compression element 62 has a relatively small friction loss and power loss compared to other types of positive displacement compression elements, and a small compressor (here, compressors 21 and 22) in the heat source unit 2. It is recommended to install multiple devices. On the other hand, in this compression element 62, since the rollers 70a and 73a and the blades 70b and 73b are formed integrally with the force S, the sliding between the pistons 70 and 73 and the bushes 71 and 74 is large.起因 Due to the high pressure caused by using carbon as a refrigerant, problems such as increased sliding load and seizure between the pistons 70 and 73 and the bushes 71 and 74 tend to occur. However, in this heat source unit 2, PAG is used as refrigeration oil, and sufficient lubrication between the pistons 70, 73 and the bushes 71, 74 can be secured. This makes it easier to incorporate multiple compressors in the heat source unit, while the use of a swing compressor causes problems such as increased sliding load between the piston and bushing and seizure. It has become possible to suppress it.

[0039] (D)

In the heat source unit 2 of the present embodiment, since the compressor motor 63 built in the compressors 21 and 22 that are hermetic compressors is controlled by the inverter device 91, A high-frequency leakage current il due to the voltage output from the barter device 91 to the compressor motor 63 is generated. For this reason, when the compressors 21 and 22 that are a plurality of hermetic compressors are provided as in the heat source unit 2, the leakage current i3 from the compressor motor 63 increases remarkably. However, since the heat source unit 2 includes the current cancellation device 95, an increase in the high-frequency leakage current il can be suppressed. As a result, a plurality of hermetic compressors with a compressor motor controlled by an inverter device are provided, and a heat source unit constituting an air conditioner that uses carbon dioxide as a refrigerant can be realized. It can be done.

[0040] (4) Other embodiments

As mentioned above, although embodiment of this invention was described based on drawing, specific structure can be changed in the range which does not deviate from the summary of this invention which is not restricted to these embodiment.

For example, in the above-described embodiment, the example in which the present invention is applied to the air conditioner 1 in which a plurality of usage units 4 are connected to one heat source unit 2 has been described. However, the present invention is not limited to this. The present invention is applied to an air conditioner in which a utilization unit and a heat source unit are connected under various connection conditions, such as application of the present invention to an air conditioner in which a plurality of utilization units are connected to a single heat source unit. The invention may be applied.

In the above-described embodiment, the example in which the present invention is applied to the air conditioner 1 that is a so-called cooling-only machine capable of performing the cooling operation has been described. However, the present invention is not limited to this, and the cooling operation and the heating operation are performed. The present invention can be applied to a cooling / heating switching machine that can be switched between, and a cooling / heating simultaneous machine that can simultaneously perform cooling operation and heating operation. The invention may be applied.

Industrial applicability

[0041] By using the present invention, it is possible to realize a heat source unit that includes a plurality of hermetic compressors and constitutes an air conditioner that uses carbon dioxide as a refrigerant.

Claims

The scope of the claims

[1] A heat source unit constituting a refrigerant circuit (10) using carbon dioxide as a refrigerant by connecting utilization units (4, 5),

A plurality of hermetic compressors (21, 22) in which a compression element (62) and a motor (63) for driving the compression element are arranged in a casing (61);

Polyalkylene glycol as refrigerating machine oil,

A current canceling device (95) for canceling the leakage current from the motor;

Heat source unit with (2).

[2] An oil reservoir (61d) for storing the refrigerator oil is formed in the casing (61),

The motor (63) is disposed so as not to immerse in the refrigerating machine oil accumulated in the oil reservoir.

The heat source unit (2) according to claim 1.

[3] The heat source unit (2) according to claim 2, wherein the motor (63) is disposed above the compression element (62).

[4] The compression element (62) includes a cylinder (72, 75) having a cylinder chamber (76, 77) formed therein, a roller (70a, 73a), and a blade (70b) integrally formed with the roller. 73b) and a piston (70, 73) that divides the cylinder chamber into a suction chamber (76a, 77a) and a discharge chamber (76b, 77b), and a bush (71, 74) that sandwiches the blade. The heat source unit (1) according to any one of claims 1 to 3, wherein the piston is configured to revolve in the cylinder chamber by the motor (63).

[5] It further comprises an inverter device (91) for controlling the motor (63),

The current canceling device (95) cancels the high-frequency leakage current caused by the inverter device;

The heat source unit (2) according to any one of claims 1 to 4.

[6] Claims 1-5! An air conditioner (1) comprising the heat source unit (2) according to any one of the above.