Scroll compressor and air conditioner

Abstract

Provided is a scroll compressor etc. having good performance and high reliability. This scroll compressor (100) comprises a compressing mechanism part (2) that compresses, in a compression chamber (C1), a refrigerant suctioned in via a suction chamber (J1) and discharges the compressed refrigerant via a discharge port (J2). The compressing mechanism part (2) has a fixed scroll (21) that includes a spiral fixed lap (21b) and an orbiting scroll (22) that includes a spiral rotary lap (22b). The compression chamber (C1) is formed between the fixed lap (21b) and the rotary lap (22b). The compressing mechanism part (2) has a liquid injection hole (H1) that guides a liquid refrigerant to the compression chamber (C1), and has a gas injection hole (H2) that guides a gas refrigerant to a compression chamber (C2). The liquid injection hole (H1) is provided at a position closer to the suction chamber (J1) than the gas injection hole (H2).

Description

[Technical Field]

[0001] The present invention relates to a scroll compressor and an air conditioner. [Background technology]

[0002] Known technology for supplying liquid refrigerant or gas refrigerant to the compression chamber of a scroll compressor is, for example, the technology described in Patent Document 1. That is, Patent Document 1 describes a scroll compressor in which a gas injection hole is provided between a suction hole and a discharge hole and closer to the suction hole, and a liquid injection hole is provided between the gas injection hole and the discharge hole. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2618501 Summary of the Invention [Problem to be solved by the invention]

[0004] In the fields of refrigeration and air conditioning, there is a demand for a shift from HFC refrigerants, which have a relatively high global warming potential (GWP), to HFO refrigerants, which have a low GWP. However, HFO refrigerants, which are expected to be new refrigerants, tend to have a narrower operating range and lower air conditioning capacity. It has also been pointed out that some HFO refrigerants are prone to a self-decomposition reaction known as a disproportionation reaction. The technology described in Patent Document 1 uses gas injection or liquid injection to improve performance, but there is room for improvement in terms of reliability when considering the use of HFO refrigerants and other refrigerants.

[0005] Therefore, an object of the present invention is to provide a scroll compressor or the like with high performance and reliability. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the scroll compressor of the present invention comprises a compression mechanism unit that compresses a refrigerant sucked through a suction chamber in a compression chamber and discharges the compressed refrigerant through a discharge port, the compression mechanism unit having a fixed scroll including a spiral fixed wrap and a spiral orbiting scroll including a spiral orbiting wrap, the compression chamber being formed between the fixed wrap and the orbiting wrap, the compression mechanism unit having a liquid injection hole for introducing liquid refrigerant or a gas-liquid two-phase refrigerant into the compression chamber, and a gas injection hole for introducing gas refrigerant into the compression chamber, the liquid injection hole being located closer to the suction chamber than the gas injection hole. [Effects of the Invention]

[0007] According to the present invention, a scroll compressor or the like with high performance and reliability can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a configuration diagram of an air conditioner equipped with a scroll compressor according to a first embodiment. [Figure 2] 1 is a vertical cross-sectional view of a scroll compressor according to a first embodiment. [Figure 3] FIG. 2 is a bottom view of a fixed scroll included in the scroll compressor according to the first embodiment. [Figure 4] 2A to 2C are explanatory diagrams illustrating the scroll compressor according to the first embodiment in each state where the rotation angle is 0°, 90°, 180°, and 270°. [Figure 5] 3 is an explanatory diagram showing the relationship between the rotation angle of the scroll compressor and the pressure in the compression chamber when liquid injection is performed in the scroll compressor according to the first embodiment. FIG. [Figure 6] 3 is an explanatory diagram showing the relationship between the rotation angle of the scroll compressor and the pressure in the compression chamber when gas injection is performed in the scroll compressor according to the first embodiment. FIG. [Figure 7]FIG. 3 is a Mollier diagram when liquid injection is performed in the scroll compressor according to the first embodiment. [Figure 8] FIG. 3 is a Mollier diagram when gas injection is performed in the scroll compressor according to the first embodiment. [Figure 9] FIG. 10 is a bottom view of a fixed scroll included in the scroll compressor according to the second embodiment. [Figure 10] 10A to 10C are explanatory diagrams illustrating the scroll compressor according to the second embodiment in each state where the rotation angle is 0°, 90°, 180°, and 270°. [Figure 11] FIG. 10 is a configuration diagram of an air conditioner equipped with a scroll compressor according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment <Air conditioner configuration> FIG. 1 is a configuration diagram of an air conditioner W1 equipped with a scroll compressor 100 according to the first embodiment. Note that arrows in Figure 1 indicate the flow of refrigerant. The air conditioner W1 is a device that performs air conditioning operations such as cooling. As shown in Figure 1, the air conditioner W1 is equipped with a scroll compressor 100, an outdoor heat exchanger 71, an outdoor fan 72, a first solenoid valve 73, a capillary tube 74, a second solenoid valve 75, and expansion valves 76a and 76b. In addition to the components described above, the air conditioner W1 is also equipped with a subcooler 77, an indoor heat exchanger 78, an indoor fan 79, an outdoor control circuit 81, and an indoor control circuit 82.

[0010] 1, the outdoor unit U1 is provided with the scroll compressor 100, the outdoor heat exchanger 71, the outdoor fan 72, the first solenoid valve 73, the capillary tube 74, the second solenoid valve 75, the expansion valve 76a, the subcooler 77, and the outdoor control circuit 81. The indoor unit U2 is provided with the expansion valve 76b, the indoor heat exchanger 78, the indoor fan 79, and the indoor control circuit 82.

[0011] The scroll compressor 100 is a device that compresses a low-temperature, low-pressure gas refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant. The outdoor heat exchanger 71 is a heat exchanger that exchanges heat between the refrigerant flowing through its heat transfer tubes (not shown) and outside air sent in from an outdoor fan 72. In the first embodiment, the air conditioner W1 is configured so that the outdoor heat exchanger 71 functions as a condenser, while the indoor heat exchanger 78 functions as an evaporator. The outdoor fan 72 is a fan that sends outside air to the outdoor heat exchanger 71, and is installed near the outdoor heat exchanger 71.

[0012] The first solenoid valve 73 is a solenoid valve that switches between supplying and blocking liquid refrigerant (or gas-liquid two-phase refrigerant) via a liquid injection hole H1 (see FIG. 2) of the scroll compressor 100. The first solenoid valve 73 is switched between open and closed states based on a command from the outdoor control circuit 81. The capillary tube 74 reduces the pressure of the refrigerant flowing through the first solenoid valve 73. As shown in FIG. 1, the outdoor heat exchanger 71, the first solenoid valve 73, and the capillary tube 74 are connected in this order via piping. The refrigerant reduced in pressure by the capillary tube 74 is supplied to the compression chamber C1 (see FIG. 4) via the liquid injection pipe P3 and the liquid injection hole H1 (see FIG. 2) in this order.

[0013] 1 is a solenoid valve that switches between supplying and blocking the gas refrigerant via a gas injection hole H2 (see FIG. 2) of the scroll compressor 100. The second solenoid valve 75 is configured to be switched between open and closed states based on a command from the outdoor control circuit 81. The expansion valve 76a reduces the pressure of the refrigerant flowing through the second solenoid valve 75. In the example of Fig. 1, the outdoor heat exchanger 71, the second solenoid valve 75, the expansion valve 76a, and the secondary flow pipe 77b of the subcooler 77 are connected in sequence via piping.

[0014] The subcooler 77 is a heat exchanger in which heat is exchanged between the refrigerant flowing through the main pipe 77a and the refrigerant flowing through the secondary pipe 77b. This cools the refrigerant flowing through the main pipe 77a, and the cooled refrigerant is further decompressed by the expansion valve 76b, thereby enhancing the air conditioning capacity of the air conditioner W1. Meanwhile, the refrigerant evaporated in the secondary pipe 77b of the subcooler 77 is supplied to the compression chamber via the gas injection pipe P4 and the gas injection hole H2 (see FIG. 2) in this order. Downstream of the outdoor heat exchanger 71, the refrigerant is branched into three pipes: a pipe K1 that guides the refrigerant to the first solenoid valve 73, a pipe K2 that guides the refrigerant to the second solenoid valve 75, and a pipe K3 that guides the refrigerant to the main pipe 77a of the subcooler 77.

[0015] The expansion valve 76b reduces the pressure of the refrigerant cooled in the main pipe 77a of the subcooler 77. The indoor heat exchanger 78 is a heat exchanger (evaporator) that exchanges heat between the refrigerant flowing through its heat transfer pipe (not shown) and indoor air sent in from an indoor fan 79. In the example of FIG. 1, the main pipe 77a of the subcooler 77, the expansion valve 76b, and the indoor heat exchanger 78 are connected in sequence via piping. The refrigerant evaporated in the indoor heat exchanger 78 is guided to the suction side of the scroll compressor 100 via a suction pipe P1. An accumulator (not shown) for separating the refrigerant into gas and liquid may be connected to the suction side of the scroll compressor 100.

[0016] The indoor fan 79 is a fan that sends indoor air to the indoor heat exchanger 78, and is installed near the indoor heat exchanger 78. The air drawn into the indoor unit U2 is cooled by heat exchange with the refrigerant in the indoor heat exchanger 78, and the cooled refrigerant is blown out into the air-conditioned room.

[0017] The outdoor control circuit 81 controls the first solenoid valve 73, the second solenoid valve 75, the expansion valve 76a, the outdoor fan 72, the scroll compressor 100, etc. in a predetermined manner based on a predetermined program. The indoor control circuit 82 controls the expansion valve 76b and the indoor fan 79 in a predetermined manner. The outdoor control circuit 81 and the indoor control circuit 82 exchange data with each other via a communication line. Although not shown, the outdoor control circuit 81 and the indoor control circuit 82 each include electronic circuits such as a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and various interfaces. The CPU reads out programs stored in the ROM and loads them into the RAM, and executes various processes. Hereinafter, the outdoor control circuit 81 and the indoor control circuit 82 will be collectively referred to as the "control unit 80."

[0018] <Scroll compressor configuration> FIG. 2 is a vertical cross-sectional view of the scroll compressor 100. The scroll compressor 100 shown in Fig. 2 is a device that compresses a gaseous refrigerant. The refrigerant used in the scroll compressor 100 may be an HFO refrigerant, or a specified refrigerant other than an HFO refrigerant. Examples of HFO refrigerants (refrigerant numbers are in parentheses) that may be used include monofluoroethylene (R1141), trans-1,2-difluoroethylene (R1132(E)), cis-1,2-difluoroethylene (R1132(Z)), 1,1-difluoroethylene (R1132a), trifluoroethylene (R1123), and tetrafluoroethylene (R1114).

[0019] 2, the scroll compressor 100 includes a sealed container 1, a compression mechanism 2, a crankshaft 3, a main bearing 4, an orbiting bearing 5, an electric motor 6, and an Oldham ring 7. In addition to the components described above, the scroll compressor 100 also includes balance weights 8 and 9, a subframe 10, an auxiliary bearing 11, an oil supply pump 12, and legs 13.

[0020] The sealed container 1 is a container that houses the compression mechanism 2, crankshaft 3, electric motor 6, etc., and is substantially sealed. The sealed container 1 includes a cylindrical tubular chamber 1a, a lid chamber 1b that closes the upper opening of the tubular chamber 1a, and a bottom chamber 1c that closes the lower opening of the tubular chamber 1a. A suction pipe P1 is inserted into and fixed to the lid chamber 1b of the sealed container 1. The suction pipe P1 is a pipe that guides the refrigerant evaporated in the indoor heat exchanger 78 (evaporator: see Figure 1) to the suction chamber J1 of the compression mechanism 2.

[0021] A discharge pipe P2 is inserted into and fixed to the cylindrical chamber 1a of the sealed container 1. The discharge pipe P2 is a tube that guides the refrigerant compressed in the compression mechanism 2 to the outside of the scroll compressor 100. The refrigerant flowing through the discharge pipe P2 is guided to an outdoor heat exchanger 71 (condenser: see FIG. 1) via piping. Lubricating oil is sealed in the sealed container 1 to improve lubrication in the scroll compressor 100, and is stored as an oil reservoir R1 at the bottom of the sealed container 1.

[0022] The compression mechanism 2 is a mechanism that compresses the refrigerant sucked through the suction chamber J1 in the compression chamber C1 and discharges the compressed refrigerant through the discharge port J2. The compression mechanism 2 includes a fixed scroll 21, an orbiting scroll 22, and a frame 23, and is disposed in the upper space within the sealed container 1.

[0023] The fixed scroll 21 is a member that forms the compression chamber C1 together with the orbiting scroll 22. The fixed scroll 21 is installed on the upper side of the frame 23 and fixed to the frame 23 with bolts (not shown). As shown in FIG. 2, the fixed scroll 21 includes a base plate 21a and a fixed wrap 21b.

[0024] The base plate 21a is a thick member having a circular shape in a plan view. The base plate 21a is provided with a suction chamber J1 to which a refrigerant is introduced via a suction pipe P1. The fixed wrap 21b is spiral-shaped (see also FIG. 3) and extends downward from the base plate 21a. The lower surface of the portion of the base plate 21a outside the fixed wrap 21b is substantially flush with the tooth tips of the fixed wrap 21b.

[0025] 2, the base plate 21a is provided with one liquid injection hole H1 and one gas injection hole H2. That is, the compression mechanism 2 has a liquid injection hole H1 and a gas injection hole H2. The liquid injection hole H1 is a hole that introduces liquid refrigerant (or gas-liquid two-phase refrigerant) into the compression chamber C1. The gas injection hole H2 is a hole that introduces gas refrigerant into the compression chamber.

[0026] As shown in Fig. 2, a liquid injection pipe P3 is inserted into the cover chamber 1b of the sealed container 1, and a gas injection pipe P4 is also inserted and fixed thereto. The liquid injection pipe P3 is a pipe that introduces liquid refrigerant (or gas-liquid two-phase refrigerant) to the liquid injection hole H1. As described above, the liquid refrigerant condensed in the outdoor heat exchanger 71 (condenser: see Fig. 1) is introduced into the liquid injection pipe P3 via the first solenoid valve 73 (see Fig. 1) and the capillary tube 74 (see Fig. 1) in this order.

[0027] The gas injection pipe P4 shown in Fig. 2 is a pipe that guides gas refrigerant to the gas injection hole H2. As described above, the gas refrigerant flows out of the outdoor heat exchanger 71 (condenser: see Fig. 1), is decompressed by the expansion valve 76a (see Fig. 1), and further evaporates in the side flow pipe 77b of the supercooler 77 (see Fig. 1), and is guided to the gas injection pipe P4.

[0028] The orbiting scroll 22 shown in Fig. 2 is a member that forms a compression chamber C1 between itself and the fixed scroll 21 by its orbit (movement). The orbiting scroll 22 includes a disk-shaped end plate 22a, a spiral orbiting wrap 22b (see also Fig. 4) standing on the end plate 22a, and a boss portion 22c that is fitted onto the eccentric portion 3b of the crankshaft 3. As shown in Fig. 2, the orbiting wrap 22b extends upward from the end plate 22a. Meanwhile, the boss portion 22c extends downward from the end plate 22a.

[0029] The spiral fixed wrap 21b of the fixed scroll 21 and the spiral orbiting wrap 22b of the orbiting scroll 22 mesh together to form a compression chamber C1 between the fixed wrap 21b and the orbiting wrap 22b. The compression chamber C1 is a space for compressing a gaseous refrigerant, and is formed on the outer line side and the inner line side of the orbiting wrap 22b (see also FIG. 4). A discharge port J2 is provided near the center of the base plate 21a of the fixed scroll 21 for discharging the refrigerant compressed in the compression chamber C1 into the upper space within the sealed container 1.

[0030] The space between the rear surface of the end plate 22a of the orbiting scroll 22 and the frame 23 functions as a back pressure chamber B1. A predetermined back pressure acts in the back pressure chamber B1 to press the orbiting scroll 22 against the fixed scroll 21.

[0031] 2 is a member for supporting the fixed scroll 21 and for fixing the main bearing 4, and has a generally rotationally symmetrical shape. The frame 23 is fixed to the sealed container 1 and also fixed to the lower side of the fixed scroll 21. The frame 23 is provided with a hole (reference number not shown) through which the crankshaft 3 is inserted.

[0032] The crankshaft 3 is a shaft that rotates integrally with the rotor 62 of the electric motor 6 and extends in the vertical direction. As shown in FIG. 2, the crankshaft 3 includes a main shaft portion 3a and an eccentric portion 3b that extends upward from the main shaft portion 3a. The main shaft portion 3a is coaxially fixed to the rotor 62 of the electric motor 6 and rotates integrally with the rotor 62. The eccentric portion 3b is a shaft that rotates eccentrically with respect to the main shaft portion 3a, and as described above, is fitted into the boss portion 22c of the orbiting scroll 22. The eccentric rotation of the eccentric portion 3b causes the orbiting scroll 22 to orbit.

[0033] Although not shown, an oil supply passage through which lubricating oil flows is provided inside the crankshaft 3. The lubricating oil flowing through the oil supply passage is guided to the compression mechanism 2 as well as to the main bearing 4, orbiting bearing 5, and sub-bearing 11. The main bearing 4 rotatably supports the upper part of the main shaft portion 3a relative to the frame 23, and is installed on the circumferential surface of a hole (reference number not shown) in the frame 23. The orbiting bearing 5 rotatably supports the eccentric portion 3b relative to the boss portion 22c of the orbiting scroll 22, and is installed on the inner circumferential surface of the boss portion 22c.

[0034] The electric motor 6 is a driving source that rotates the crankshaft 3 and is installed inside the sealed container 1. The electric motor 6 includes a stator 61 and a rotor 62, and is installed between the frame 23 and the subframe 10. The stator 61 is fixed to the inner peripheral surface of the cylindrical chamber 1a by press fitting or the like. The rotor 62 is rotatably disposed radially inside the stator 61. When a predetermined current is applied via the windings of the stator 61, magnetic attractive and repulsive forces are generated, causing the rotor 62 to rotate.

[0035] The Oldham ring 7 is a ring-shaped member that receives the eccentric rotation of the eccentric portion 3b and orbits the orbiting scroll 22 without rotating on its axis. The Oldham ring 7 is provided between the orbiting scroll 22 and the frame 23. The balance weights 8, 9 are members for suppressing vibration of the scroll compressor 100. In the example of FIG. 2, the balance weight 8 is provided between the compression mechanism 2 and the electric motor 6, and is fixed to the crankshaft 3. When the electric motor 6 is driven, the balance weight 8 rotates integrally with the crankshaft 3. The other balance weight 9 is provided below the rotor 62 of the electric motor 6. The balance weight 9 has a semicircular shape when viewed from below, and is provided on the opposite side of the one balance weight 8 in the circumferential direction.

[0036] The sub-frame 10 supports the lower part of the crankshaft 3 and is fixed to the inner peripheral surface of the sealed container 1. The sub-bearing 11 supports the lower part of the crankshaft 3 and is a bearing that receives a radial load from the crankshaft 3. The sub-bearing 11 is fixed to the peripheral surface of a hole (reference number not shown) in the sub-frame 10 by press-fitting or the like.

[0037] The oil supply pump 12 is a pump that sucks up lubricating oil from the oil reservoir R1 in the sealed container 1 and directs it to an oil supply passage (not shown) in the crankshaft 3, and is installed at the lower end of the crankshaft 3. For example, a trochoid pump is used as this oil supply pump 12. The legs 13 support the sealed container 1 and are installed in the bottom chamber 1c.

[0038] <Refrigerant injection> HFO refrigerants have the advantage of a low global warming potential (GWP), but they tend to increase the temperature of the discharge gas and the compression ratio. As a result, the operating range of the scroll compressor 100 (the operable refrigerant pressure range) tends to be narrowed and the air conditioning capacity tends to be reduced. Furthermore, HFO refrigerants (especially fluoroethylene-based refrigerants) may undergo a self-decomposition reaction known as a disproportionation reaction. A disproportionation reaction is a phenomenon in which, when a certain amount of ignition energy is applied in a high-temperature, high-pressure environment, a certain reaction proceeds in a chain reaction, generating a large amount of reaction heat and a sudden increase in pressure.

[0039] Therefore, in the first embodiment, the disproportionation reaction of the refrigerant is suppressed by liquid injection, while the operating range of the scroll compressor 100 is expanded, and high efficiency is achieved by gas injection.

[0040] FIG. 3 is a bottom view of the fixed scroll 21 provided in the scroll compressor. As shown in Fig. 3, one liquid injection hole H1 and one gas injection hole H2 are provided in the base plate 21a of the fixed scroll 21. As described above, the liquid injection hole H1 is a hole that guides the liquid refrigerant (or gas-liquid two-phase refrigerant) condensed in the outdoor heat exchanger 71 (see Fig. 1) to the compression chamber. The gas injection hole H2 is a hole that guides the gas refrigerant evaporated in the side flow pipe 77b (see Fig. 1) of the subcooler 77 (see Fig. 1) to the compression chamber.

[0041] 3, the liquid injection hole H1 is located closer to the suction chamber J1 than the gas injection hole H2. Note that "closer to the suction chamber J1" means that in the spiral gap between the fixed wraps 21b (the spiral path from the suction chamber J1 to the discharge port J2), the liquid injection hole H1 is closer to the suction chamber J1 than the gas injection hole H2. In addition, the radial distance between the liquid injection hole H1 and the center of the discharge port J2 is longer than the radial distance between the gas injection hole H2 and the center of the discharge port J2.

[0042] The liquid injection hole H1 and the gas injection hole H2 are each provided near the center of the gap between the fixed wraps 21b in the radial direction centered on the discharge port J2. The action and effect of this positional relationship will be described later. The diameter of the liquid injection hole H1 is smaller than the thickness of the orbiting wrap 22b (see FIG. 4). Similarly, the diameter of the gas injection hole H2 is also smaller than the thickness of the orbiting wrap 22b (see FIG. 4). This prevents the liquid injection hole H1 and the gas injection hole H2 from simultaneously communicating with the compression chambers on the outer line side and inner line side of the orbiting wrap 22b (see FIG. 4).

[0043] FIG. 4 is an explanatory diagram showing the states in which the rotation angle of the scroll compressor is 0°, 90°, 180°, and 270°. In Fig. 4, the orbiting wrap 22b is hatched, and among the multiple compression chambers, a predetermined compression chamber C1 formed on the inner line side of the orbiting wrap 22b is indicated by a dot. As shown in Fig. 4, multiple compression chambers are formed on the inner line side and the outer line side of the orbiting wrap 22b, but the following description will focus on the predetermined compression chamber C1 indicated by a dot in Fig. 4.

[0044] When the scroll compressor 100 is at a rotation angle of 0°, the compression chamber C1 has just been formed near the suction chamber J1. At a rotation angle of 0°, the orbiting wrap 22b overlaps the liquid injection hole H1, and the liquid injection hole H1 is not yet connected to the compression chamber C1. Furthermore, the gas injection hole H2 is not yet connected to the compression chamber C1.

[0045] When the scroll compressor 100 is at a rotation angle of 90°, the liquid injection hole H1 communicates with the compression chamber C1. When the first solenoid valve 73 (see FIG. 1) is open in this state, the liquid refrigerant condensed in the outdoor heat exchanger 71 is injected into the compression chamber C1 through the liquid injection hole H1. As a result, the temperature drops due to the heat of vaporization when the liquid refrigerant evaporates into a gas in the compression chamber C1. As described below, this not only expands the operating range of the scroll compressor 100 but also suppresses the disproportionation reaction of the refrigerant.

[0046] As shown in the state of a rotation angle of 90° in Figure 4, the liquid injection hole H1 is located in a position that does not communicate with the suction chamber J1, but is located in a position that communicates with the compression chamber C1 immediately after the compression chamber C1 is formed. As will be described in detail later, this arrangement promotes cooling in the compression chamber C1 due to the latent heat of vaporization, and also reduces pressure pulsation associated with liquid injection, as will be described later.

[0047] As shown in Fig. 4, the liquid injection hole H1 and the gas injection hole H2 are provided at positions where they do not communicate with each other. In other words, the liquid injection hole H1 and the gas injection hole H2 do not communicate with each other through a specific compression chamber. In the example of Fig. 4, the liquid injection hole H1 is provided near the suction chamber J1, and the gas injection hole H2 is provided near the discharge port J2. This makes it possible to expand the operating range of the scroll compressor 100, suppress disproportionation reactions, and achieve high efficiency, as will be described later.

[0048] 4, when the rotation angle of the scroll compressor 100 is 180°, another compression chamber C2 is in communication with the gas injection hole H2, but the compression chamber C1 does not yet communicate with the gas injection hole H2. At a rotation angle of 270°, the compression chamber C1 is quite close to the gas injection hole H2, but the orbiting wrap 22b overlaps with the gas injection hole H2.

[0049] Then, when the rotation angle of the scroll compressor 100 returns to 0°, the compression chamber C1 communicates with the gas injection hole H2 (not shown). If the second solenoid valve 75 (see FIG. 1) is open in this state, the gas refrigerant evaporated in the subcooler 77 (see FIG. 1) is injected into the compression chamber C1 through the gas injection hole H2. As will be described in detail later, by injecting gas in the latter half of the refrigerant compression process, backflow of the refrigerant into the suction chamber J1 is suppressed, thereby reducing heating loss. Note that the states at each rotation angle shown in FIG. 4 are merely examples and are not limited to these.

[0050] Furthermore, it is not necessary to perform both liquid injection and gas injection simultaneously. In other words, the control unit 80 (see FIG. 1) may perform liquid injection when a predetermined condition is met, and may perform gas injection when another condition is met. In this way, the control unit 80 (see FIG. 1) independently controls the first solenoid valve 73 (see FIG. 1) and the second solenoid valve 75 (see FIG. 1), so that liquid injection and gas injection can be performed individually based on predetermined conditions. The conditions for liquid injection and gas injection will be described later.

[0051] FIG. 5 is an explanatory diagram showing the relationship between the rotation angle of the scroll compressor and the pressure in the compression chamber when liquid injection is performed. The horizontal axis in Fig. 5 represents the rotation angle of the scroll compressor 100 (see Fig. 2). When the rotation angle is 0°, the compression chamber C1 (see "Rotation angle 0°" in Fig. 4) closest to the suction chamber J1 is formed, and suction is completed. The vertical axis in Fig. 5 represents the pressure in the compression chamber C1 (see Fig. 4).

[0052] The dashed line graph in FIG. 5 is a predetermined theoretical adiabatic curve. The dashed line graph in FIG. 5 is an indicator diagram when liquid injection is performed in a configuration of a comparative example. The configuration of the comparative example is a configuration in which liquid injection, rather than gas injection, is performed at the position of the gas injection hole H2 shown in FIG. 3. The solid line graph in FIG. 5 is an indicator diagram when liquid injection is performed in the configuration of the first embodiment. Note that with respect to the solid line graph in FIG. 5, it is assumed that gas injection is not performed.

[0053] As described above, the liquid injection hole H1 communicates with the compression chamber C1 immediately after the compression chamber C1 (see FIG. 4) is formed. As a result, the pressure in the compression chamber C1 immediately before the liquid injection hole H1 and the compression chamber C1 start to communicate with each other is equal to the suction pressure P s Therefore, immediately after the start of liquid injection (rotation angle θ1), the pressure P of the liquid refrigerant in the liquid injection hole H1 becomesL_inj and the pressure in the compression chamber C1 (suction pressure P s ) and the pressure difference ΔP1 between them becomes quite large. As a result, the flow rate and speed of the liquid refrigerant heading towards the compression chamber C1 are sufficiently secured, and cooling is promoted in the compression chamber C1 due to the heat of vaporization, thereby suppressing the occurrence of disproportionation reactions.

[0054] Furthermore, the liquid injection hole H1 (see FIG. 4) is located near the suction chamber J1 but not in communication with the suction chamber J1. This prevents high-pressure liquid refrigerant from flowing into the suction chamber J1 through the liquid injection hole H1. This reduces heating loss during refrigerant compression, resulting in higher efficiency.

[0055] Furthermore, because excessive increases in discharge temperature are suppressed even when an HFO refrigerant is used, the operating range of the scroll compressor 100 can be expanded even when an HFO refrigerant, which tends to have a high pressure ratio, is used. As described above, the "operating range" of the scroll compressor 100 refers to the pressure range in which operation is possible at each rotation speed. In the comparative example (dashed line) in Figure 5, the timing at which liquid injection starts (rotation angle θ3) is delayed, so the differential pressure ΔP3 is small, and as a result, the flow rate and flow velocity of the liquid refrigerant during liquid injection are small.

[0056] In the example of FIG. 5, liquid injection is performed from a rotation angle θ1 immediately after the formation of the compression chamber C1 to a predetermined rotation angle θ2. Also, in the first half of the refrigerant compression process, the gradient of the pressure increase in the compression chamber C1 is relatively small. Therefore, in the configuration of the first embodiment (solid line graph), the pressure fluctuation range ΔP2 in the compression chamber C1 between the start (rotation angle θ1) and end (rotation angle θ2) of the liquid injection is suppressed. As a result, pressure pulsation due to liquid injection is reduced, and noise and vibration of the scroll compressor 100 can be suppressed. Note that in the comparative example (dashed line), the timing of the end of liquid injection (rotation angle θ4) is delayed, resulting in a large pressure fluctuation range ΔP4, which in turn increases the pressure pulsation due to liquid injection.

[0057] FIG. 6 is an explanatory diagram showing the relationship between the rotation angle of the scroll compressor and the pressure in the compression chamber when gas injection is performed. The horizontal axis of FIG. 6 represents the rotation angle of the scroll compressor 100 (see FIG. 2). The vertical axis of FIG. 6 represents the pressure in the compression chamber C1 (see FIG. 4). The dashed line graph in FIG. 6 represents a predetermined theoretical adiabatic curve. The dotted line graph in FIG. 6 represents an indicator pressure diagram when gas injection is performed in a configuration of a comparative example. The configuration of the comparative example is a configuration in which gas injection, not liquid injection, is performed at the position of the liquid injection hole H1 shown in FIG. 3. The solid line graph in FIG. 6 represents an indicator pressure diagram when gas injection is performed in the configuration of the first embodiment. It is assumed that liquid injection is not performed in the solid line graph in FIG. 6.

[0058] As described above, in the first embodiment, the gas injection hole H2 (see FIG. 3) is provided closer to the discharge port J2 than the liquid injection hole H1 (see FIG. 3). As a result, the pressure P of the compression chamber C1 immediately before communication between the gas injection hole H2 and the compression chamber C1 begins G_NEW Therefore, immediately after the start of gas injection (rotation angle θ7), the pressure P of the gas refrigerant in the gas injection hole H2 G_inj and the pressure P in the compression chamber C1 G_NEW The differential pressure ΔP7 between the compression chamber C1 and the suction chamber J1 is reduced. As a result, backflow of refrigerant from the compression chamber C1 to the suction chamber J1 is suppressed, reducing heating loss and improving efficiency. In the comparative example (dashed line), the timing of the start of gas injection (rotation angle θ6) is early, so the differential pressure ΔP6 described above increases, and as a result, the heating loss also increases.

[0059] FIG. 7 is a Mollier diagram when liquid injection is performed. In Figure 7, the horizontal axis represents the specific enthalpy of the refrigerant, and the vertical axis represents the pressure of the refrigerant. A saturated vapor line 91 shown in Figure 7 is the boundary between the gas phase and the two-phase gas-liquid state of the refrigerant. A saturated liquid line 92 shown in Figure 7 is the boundary between the liquid phase and the two-phase gas-liquid state of the refrigerant. In the region surrounded by the saturated vapor line 91 and the saturated liquid line 92, the refrigerant is in a two-phase gas-liquid state. The boundary point between the saturated vapor line 91 and the saturated liquid line 92 is called a critical point 93.

[0060] The trapezoidal dashed line M1 in Figure 7 is a Mollier diagram when neither liquid injection nor gas injection is performed. The solid line M2 in Figure 7 is a Mollier diagram when liquid injection is performed in the first embodiment. Note that the solid line M2 assumes that gas injection is not performed. In the first embodiment, liquid injection near the suction chamber J1 (see Figure 4) reduces the specific enthalpy of the refrigerant (see arrow A1 in Figure 7). This can suppress the occurrence of disproportionation reactions when using an HFO refrigerant.

[0061] FIG. 8 is a Mollier diagram when gas injection is performed. The trapezoidal dashed line M1 in FIG. 8 is a Mollier diagram when neither liquid injection nor gas injection is performed. The solid line M3 in FIG. 8 is a Mollier diagram when gas injection is performed in the first embodiment. Note that the solid line M3 assumes that liquid injection is not performed. In the first embodiment, gas injection is performed near the discharge port J2 (see FIG. 4), thereby decreasing the specific enthalpy of the refrigerant (see arrow A2 in FIG. 8). This increases the compression efficiency of the refrigerant, thereby achieving high efficiency.

[0062] Although not shown in the figure, when both liquid injection and gas injection are performed simultaneously, the specific enthalpy decreases in two stages during the refrigerant compression process, so that the disproportionation reaction can also be suppressed and the efficiency can be increased.

[0063] <Liquid injection conditions> For example, when the pressure ratio in the scroll compressor 100 is equal to or greater than a predetermined value, the control unit 80 may open the first solenoid valve 73. Here, the "pressure ratio" refers to the ratio of the discharge pressure to the suction pressure of the scroll compressor 100. In this way, when the pressure ratio is equal to or greater than a predetermined value, the control unit 80 opens the first solenoid valve 73, whereby liquid refrigerant is supplied to the compression chambers and the refrigerant in the compression chambers is cooled. This prevents the discharge temperature from reaching a predetermined upper limit temperature, thereby expanding the operating range of the scroll compressor 100. Note that the pressure ratio may be calculated based on the detected values ​​of the suction pressure and discharge pressure of the scroll compressor 100, or may be calculated based on the detected values ​​of the pressure or temperature at other predetermined locations.

[0064] Furthermore, when the discharge temperature of the scroll compressor 100 is equal to or higher than a predetermined value, the control unit 80 may open the first solenoid valve 73. This allows liquid refrigerant to be supplied through the liquid injection hole H1, and the refrigerant is cooled in the compression chamber C1 by the heat of vaporization. As a result, the temperature rise of the refrigerant is suppressed, thereby expanding the operating range of the scroll compressor 100 and suppressing the disproportionation reaction that occurs when an HFO refrigerant is used. A temperature sensor (not shown) is provided to detect the discharge temperature of the scroll compressor 100, and the detected value is output to the control unit 80 (see FIG. 1). When liquid injection is performed, gas injection may or may not be performed simultaneously.

[0065] <Gas injection conditions> Furthermore, when the outdoor air temperature is below a predetermined value, the control unit 80 may be configured to open the second solenoid valve 75. When the air conditioner W1 is used in a cold region or in a low-temperature environment in winter and the outdoor air temperature falls below a predetermined value, the refrigerant circulation flow rate decreases, which tends to result in lower efficiency. In particular, HFO refrigerants have a relatively low density, which tends to result in lower circulation flow rates. Therefore, the control unit 80 opens the second solenoid valve 75 when the outdoor air temperature is below a predetermined value. This allows high-pressure gas refrigerant to be supplied to the compression chamber, thereby improving operating efficiency. It is assumed that an outdoor temperature sensor (not shown) for detecting the outdoor air temperature is installed in the outdoor unit U1 (see FIG. 1).

[0066] Furthermore, when the scroll compressor 100 is operating under a predetermined overload condition, the control unit 80 may open the second solenoid valve 75. The "overload condition" is set in advance based on the rotational speed, discharge pressure, etc. of the scroll compressor 100. This prevents the scroll compressor 100 from shutting down due to predetermined protective control, and allows the scroll compressor 100 to continue operating at high efficiency. Furthermore, when gas injection is performed, liquid injection may be performed at the same time, or liquid injection may not be performed at all.

[0067] <Effects> According to the first embodiment, liquid refrigerant is supplied to the compression chamber C1 through the liquid injection hole H1 (see FIG. 4) near the suction chamber J1. This reduces the temperature in the compression chamber C1 due to the heat of vaporization generated when the liquid refrigerant evaporates into gas, thereby suppressing disproportionation reactions and expanding the operating range of the scroll compressor 100. Furthermore, the use of an HFO refrigerant with a low global warming potential (GWP) contributes to the suppression of global warming.

[0068] Furthermore, by supplying gas refrigerant through the gas injection hole H2 (see FIG. 4), the scroll compressor 100 can be operated with high efficiency. As described above, according to the first embodiment, the performance and reliability of the scroll compressor 100 are improved.

[0069] Second Embodiment The second embodiment differs from the first embodiment in that two liquid injection holes H11, H12 (see FIG. 9) and two gas injection holes H21, H22 (see FIG. 9) are provided in the fixed scroll 21A (see FIG. 9). The other configurations are the same as those of the first embodiment. Therefore, only the parts that are different from the first embodiment will be described, and a description of the overlapping parts will be omitted.

[0070] FIG. 9 is a bottom view of a fixed scroll 21A included in the scroll compressor according to the second embodiment. As shown in Fig. 9, the fixed scroll 21A is provided with two liquid injection holes H11, H12 and two gas injection holes H21, H22. The two liquid injection holes H11, H12 are arranged side by side in the radial direction around the discharge port J2, along the edge of the fixed wrap 21b. One of the liquid injection holes, H11, is a hole that communicates with the compression chamber on the outer line side of the orbiting wrap 22b (see Fig. 10). The other liquid injection hole, H12, is a hole that communicates with the compression chamber on the inner line side of the orbiting wrap 22b (see Fig. 10).

[0071] These liquid injection holes H11, H12 are located closer to the suction chamber J1 than the gas injection holes H21, H22. That is, in the spiral gap between the fixed wraps 21b (the spiral path from the suction chamber J1 to the discharge port J2), the liquid injection holes H11, H12 are located closer to the suction chamber J1 than the gas injection holes H21, H22.

[0072] When the first solenoid valve 73 (see FIG. 1) is opened and the liquid injection holes H11, H12 communicate with predetermined compression chambers, liquid refrigerant (or gas-liquid two-phase refrigerant) is supplied to each compression chamber via the liquid injection holes H11, H12. The liquid injection pipe P3 (see FIG. 1) branches into two, and the downstream ends of the two branches are connected to the liquid injection holes H11, H12.

[0073] The two gas injection holes H21, H22 are arranged side by side in the radial direction around the discharge port J2 along the edge of the fixed wrap 21b. One gas injection hole H21 is a hole that communicates with the compression chamber on the outer line side of the orbiting wrap 22b (see FIG. 10). The other gas injection hole H22 is a hole that communicates with the compression chamber on the inner line side of the orbiting wrap 22b (see FIG. 10).

[0074] When the second solenoid valve 75 (see FIG. 1) is opened and the gas injection holes H21, H22 communicate with predetermined compression chambers, gas refrigerant is supplied to each compression chamber via the gas injection holes H21, H22. The gas injection pipe P4 (see FIG. 1) branches into two, and the downstream ends of the two branches are connected to the gas injection holes H21, H22.

[0075] FIG. 10 is an explanatory diagram showing the states in which the rotation angle of the scroll compressor is 0°, 90°, 180°, and 270°. For example, when focusing on compression chamber C3 on the inner side of orbiting wrap 22b, it communicates with liquid injection hole H12 at a rotation angle of 90°, and with gas injection hole H22 at a rotation angle of 270°. When focusing on compression chamber C4 on the outer side of orbiting wrap 22b, it communicates with liquid injection hole H11 at rotation angles of 0° and 90°, and with gas injection hole H21 at rotation angles of 90°, 180°, and 270°. In this way, liquid injection and gas injection are performed for each of the compression chambers that are formed one after another.

[0076] It is not necessary to perform liquid injection and gas injection simultaneously, but liquid injection may be performed when a predetermined condition is satisfied, and gas injection may be performed when another condition is satisfied. The above-mentioned conditions are the same as those in the first embodiment, so a description thereof will be omitted.

[0077] <Effects> According to the second embodiment, regardless of whether liquid injection or gas injection is performed, refrigerant is injected onto both the outer and inner sides of the orbiting wrap 22b. This allows liquid injection or gas injection into each of the compression chambers formed one after another. Therefore, in addition to suppressing disproportionation reactions when an HFO refrigerant is used, the scroll compressor 100 can be expanded in its operating range and more efficiently operated than in the first embodiment.

[0078] Third Embodiment The third embodiment differs from the first embodiment in the configuration of the air conditioner W2 (see FIG. 11). However, other aspects (such as the configuration of the scroll compressor 100: see FIGS. 2 and 3) are the same as those of the first embodiment. Therefore, only the parts that differ from the first embodiment will be described, and a description of the overlapping parts will be omitted.

[0079] FIG. 11 is a configuration diagram of an air conditioner equipped with a scroll compressor according to the third embodiment. 11, a portion of the refrigerant condensed in the outdoor heat exchanger 71 is guided to the second solenoid valve 75 via piping K2, and the remaining refrigerant is guided to the main pipe 77a of the subcooler 77 via piping K3. When the second solenoid valve 75 is open, the refrigerant flowing out through the second solenoid valve 75 is decompressed by the expansion valve 76a, and then evaporated in the side flow pipe 77b of the subcooler 77, and then guided to the gas injection hole H2 (see FIG. 2) via the gas injection pipe P4.

[0080] Furthermore, a portion of the refrigerant cooled in the main pipe 77a of the subcooler 77 is guided to the first solenoid valve 73 via pipe K4, and the remaining refrigerant is guided to the indoor heat exchanger 78 via an expansion valve 76b. When the first solenoid valve 73 is open, the refrigerant flowing out through the first solenoid valve 73 is decompressed by the capillary tube 74 and is further guided to the liquid injection hole H1 (see FIG. 2) via the liquid injection pipe P3. Note that the connections other than the first solenoid valve 73 and the capillary tube 74 are the same as those in the first embodiment (see FIG. 1), and therefore will not be described again.

[0081] <Effects> According to the third embodiment, the refrigerant is cooled in the main pipe 77a of the subcooler 77 and further decompressed in the capillary tube 74, and is introduced into the liquid injection hole H1 (see FIG. 2). As a result, cooling is promoted in the compression chamber C1 (see FIG. 4) by the heat of vaporization phenomenon when the liquid refrigerant evaporates into gas through the liquid injection hole H1. Therefore, the operating range of the scroll compressor 100 can be expanded, and the disproportionation reaction of the refrigerant can be suppressed.

[0082] <<Variations>> Although the scroll compressor 100 and the air conditioners W1 and W2 according to the present invention have been described in the above in relation to the respective embodiments, the present invention is not limited to these descriptions and various modifications can be made. For example, in the first embodiment, the control unit 80 performs liquid injection when a predetermined condition is met, and performs gas injection when another condition is met. However, the present invention is not limited to this. That is, the control unit 80 (see FIG. 1) may always open one or both of the first solenoid valve 73 (see FIG. 1) used for liquid injection and the second solenoid valve 75 (see FIG. 1) used for gas injection. The same can be said for the second and third embodiments.

[0083] The number and positions of the liquid injection hole H1 (see FIG. 3) and the gas injection hole H2 (see FIG. 3) described in the first embodiment can be changed as appropriate. Note that the liquid injection hole H1 is provided closer to the suction chamber J1 than the gas injection hole H2.

[0084] Furthermore, the respective embodiments can be combined as appropriate. For example, the first and second embodiments may be combined to form a configuration in which one liquid injection hole H1 (see FIG. 3) and two gas injection holes H21, H22 (see FIG. 9) are provided. Alternatively, two liquid injection holes H11, H12 (see FIG. 9) and one gas injection hole H2 (see FIG. 3) may be provided. In addition, the second embodiment and the third embodiment may be combined to form an air conditioner W2 (see FIG. 11) having the configuration of the third embodiment using a scroll compressor 100 having two liquid injection holes H11, H12 (see FIG. 9) and two gas injection holes H21, H22.

[0085] In addition, in each embodiment, the case where the liquid refrigerant is guided from the outdoor heat exchanger 71 (see FIG. 1) to the liquid injection hole H1 (see FIG. 2) of the scroll compressor 100 via the first solenoid valve 73 and the capillary tube 74 in this order has been described, but this is not limiting. For example, the capillary tube 74 may be omitted as appropriate, or an expansion valve (not shown) may be provided instead of the capillary tube 74.

[0086] In addition, in each embodiment, the case where the gas refrigerant is guided from the outdoor heat exchanger 71 (see FIG. 1) to the gas injection hole H2 (see FIG. 2) of the scroll compressor 100 via the second solenoid valve 75, the expansion valve 76a, and the secondary flow pipe 77b of the subcooler 77 in this order has been described, but this is not limiting. For example, at least one of the expansion valve 76a and the subcooler 77 may be omitted.

[0087] In addition, in each embodiment, a configuration in which the scroll compressor 100 is installed vertically has been described, but this is not limiting. For example, each embodiment can also be applied to a configuration in which the scroll compressor 100 is installed horizontally or obliquely. Furthermore, the air conditioner W1 described in each embodiment can be applied to various types of air conditioners, such as room air conditioners, package air conditioners, and multi-air conditioners for buildings.

[0088] In the first embodiment, the air conditioner W1 (see FIG. 1) is not particularly provided with a four-way valve (not shown) and is configured exclusively for cooling. However, the air conditioner may be provided with a four-way valve (not shown) that switches between the cooling cycle and the heating cycle based on the operation mode. Furthermore, a flow path switching device (not shown) may be separately provided that switches the refrigerant flow path depending on the operation mode, so that liquid refrigerant is introduced into the liquid injection hole H1 (see FIG. 3) and gas refrigerant is introduced into the gas injection hole H2 (see FIG. 3). The air conditioner may also be configured exclusively for heating. The same can be said for the second and third embodiments.

[0089] In the first embodiment, an air conditioner W1 (see FIG. 1) equipped with the scroll compressor 100 has been described, but the present invention is not limited to this. For example, the first embodiment can also be applied to other refrigeration cycle devices such as refrigerators, water heaters, air-conditioning water heaters, and chillers. The same can be said for the second and third embodiments.

[0090] Furthermore, each embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to having all of the configurations described. Furthermore, part of the configuration of each embodiment can be appropriately added to, deleted from, or replaced with other configurations. Furthermore, the mechanisms and configurations described above are those that are considered necessary for the explanation, and do not necessarily represent all mechanisms and configurations of the product. [Explanation of symbols]

[0091] 1. Airtight container 2 Compression mechanism 3 crankshaft 4 Main bearing 5 Slewing bearing 6 Electric motor 21,21A Fixed scroll 21b fixed wrap 22 Swivel Scroll 22b Circling Wrap 23 frames 71 Outdoor heat exchanger 72 Outdoor fan 73 First solenoid valve 74 Capillary Tube 75 Second solenoid valve 76b Expansion valve 77 Supercooler 78 Indoor heat exchanger 79 Indoor fan 80 Control Unit 100 Scroll Compressor C1, C2, C3, C4 compression chambers H1, H11, H12 liquid injection holes H2, H21, H22 gas injection holes J1 suction chamber J2 outlet W1, W2 air conditioner

Claims

1. a compression mechanism that compresses a refrigerant drawn in through a suction chamber in a compression chamber and discharges the compressed refrigerant through a discharge port; The compression mechanism includes a fixed scroll including a spiral-shaped fixed wrap and an orbiting scroll including a spiral-shaped orbiting wrap, The compression chamber is formed between the fixed wrap and the orbiting wrap, the compression mechanism portion has a liquid injection hole for introducing a liquid refrigerant or a gas-liquid two-phase refrigerant into the compression chamber, and also has a gas injection hole for introducing a gas refrigerant into the compression chamber, The liquid injection hole is provided at a position closer to the suction chamber than the gas injection hole.

2. The liquid injection hole and the gas injection hole are provided at positions where they do not communicate with each other.

2. The scroll compressor according to claim 1,

3. The liquid injection hole and the gas injection hole are each provided near the center of the gap between the fixed wraps in a radial direction centered on the discharge port.

2. The scroll compressor according to claim 1,

4. The liquid injection hole is provided at a position that does not communicate with the suction chamber, but at a position that communicates with the compression chamber immediately after the compression chamber is formed.

2. The scroll compressor according to claim 1,

5. the compression mechanism portion has two liquid injection holes, The two liquid injection holes are arranged side by side in the radial direction around the discharge port so as to be aligned along the edge of the fixed wrap.

2. The scroll compressor according to claim 1,

6. the compression mechanism portion has two gas injection holes, The two gas injection holes are arranged side by side in the radial direction around the discharge port so as to be aligned along the edge of the fixing wrap.

2. The scroll compressor according to claim 1,

7. A compressor comprising: the scroll compressor according to any one of claims 1 to 6; an outdoor heat exchanger; an expansion valve; and an indoor heat exchanger; a first solenoid valve that switches between supplying and blocking the liquid refrigerant or the gas-liquid two-phase refrigerant through the liquid injection hole; a second solenoid valve that switches between supplying and blocking the gas refrigerant through the gas injection hole; a control unit that controls the first solenoid valve and the second solenoid valve independently.

8. The control unit opens the first solenoid valve when a pressure ratio in the scroll compressor is equal to or greater than a predetermined value, or when a discharge temperature of the scroll compressor is equal to or greater than a predetermined value.

8. The air conditioner according to claim 7,

9. The control unit opens the second solenoid valve when the outside air temperature is equal to or lower than a predetermined value or when the scroll compressor is operated under a predetermined overload condition.

8. The air conditioner according to claim 7,

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