JP2003269808A - Air conditioner - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide an air conditioner that can be operated with a high coefficient of performance (high energy saving) throughout the year by improving efficiency according to the actual conditions of the use environment. An air conditioner in which a compressor 1, a heat source side heat exchanger 3, a first decompression device 4, a receiver 5, a second decompression device 7a, and a use side heat exchanger 8 are sequentially connected by piping to form a refrigeration cycle. , Injection circuits 111 and 112 connected from the receiver 5 to the compression chamber of the compressor 1, and a bypass circuit 110 connected from the injection circuit to the suction pipe 109 of the compressor 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having a steam compressor type heat pump cycle, and in particular, when operating under an intermediate load (intermediate capacity), the operating efficiency is improved to save energy. Suitable for ones.

[0002]

2. Description of the Related Art Conventionally, an air conditioner provided with an injection circuit is known as a highly efficient cycle for increasing the coefficient of performance of the air conditioner. For example, Japanese Patent Laid-Open No. 10-
In 176866 publication, as a method for realizing a high performance coefficient operation in a wide range of performance, it is described that an injection circuit is provided and the operation having the higher performance coefficient is selected from the injection operation and the non-injection operation.

As a compressor capacity control means, a method is known in which a refrigerant is extracted from a compression chamber and bypassed, and is described in, for example, Japanese Patent Application Laid-Open No. 9-256974.
Further, Japanese Patent Laid-Open No. 11-351167 discloses that multi-stage capacity control is performed as a scroll compressor capable of changing a partial load operation of 50% or less in multiple stages.

[0004]

In the above prior art, the coefficient of performance of the air conditioner is increased by using the gas injection cycle, but the effect becomes smaller as the pressure ratio becomes smaller. That is, when the load is large, the effect of gas injection is large, but when the load is small, the effect is small. On the other hand, in the environment where the air conditioner is generally used, there are many cases where the load is low and medium, and it is not sufficient to save energy, particularly annual power. In addition, although the capacity control of the compressor according to the above-mentioned conventional technology has multiple stages, the capacity control range is much narrower and the energy saving effect is smaller than that of the inverter controller, which is currently the mainstream of energy saving models.

An object of the present invention is to provide an air conditioner which improves efficiency in accordance with the actual conditions of use and can operate with a high coefficient of performance (high energy saving) throughout the year.

Another object of the present invention is to extend the operating range from low load to high load, that is, in the case of a model of inverter control, it is possible to further reduce the capacity even when the compressor is at the minimum operating frequency. It is in.

Further, even if the model does not have the inverter control, the capacity control can be carried out regardless of the presence or absence of the inverter control,
It is to be able to select the operation method suitable for energy saving.
The present invention is to achieve at least one of the above objects.

[0008]

In order to achieve the above object, the present invention sequentially arranges a compressor, a heat source side heat exchanger, a first pressure reducing device, a receiver, a second pressure reducing device and a utilization side heat exchanger. In an air conditioner that is connected by the above to form a refrigeration cycle, an air conditioner that includes an injection circuit that is connected from the receiver to the compression chamber of the compressor and a bypass circuit that is connected from the injection circuit to the suction side pipe of the compressor. is there.

Further, in the above, it is desirable to provide a flow path switching valve at the connection point between the injection circuit and the bypass circuit and switch the connection of the injection circuit to the compression chamber to the connection to the suction side pipe.

Further, in the above, it is desirable to provide a flow passage opening / closing valve between the connection point of the injection circuit and the bypass circuit and the receiver.

Further, in the above, it is desirable to open the bypass circuit in relation to the outdoor temperature and the indoor temperature.

Further, in the above-mentioned compressor, the compressor is a variable displacement type compressor whose operating frequency is controlled from the minimum frequency to the maximum frequency, and when the operating frequency becomes the minimum frequency, the bypass circuit is opened to inject injection. It is desirable not to do it.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show a system configuration of a heat pump cycle of an air conditioner, a compressor 1,
Four-way valve 2, heat source side heat exchanger (outdoor heat exchanger) 3, first pressure reducing device 4, receiver 5, blocking valve 6, second pressure reducing device 7a,
The utilization side heat exchanger (indoor heat exchanger) 8a, the blocking valve 9, and the compressor 1 are sequentially connected by piping. Further, an injection circuit (a circuit that connects the pipe 111, the pipe 112, and the pipe 109) that connects the receiver 5 and the compression chamber of the compressor 1 in the compression process is provided, and a bypass that connects the injection circuit and the suction side pipe 108 of the compressor 1 It has a circuit (pipe 110).

A three-way valve 10, which is a flow path switching valve, is provided at a connection point between the injection circuit and the bypass circuit to switch between the bypass circuit and the injection circuit. In addition, a capillary tube 12 is provided in the bypass circuit (pipe 110) as a pressure reducing device to adjust the flow rate of the refrigerant flowing through the bypass circuit. A flow rate adjusting valve or an electronic expansion valve may be used instead of the capillary tube 12.

Further, a solenoid valve 11 is provided in the injection circuit (pipe 111, pipe 112) between the three-way valve 10 and the receiver 5 so that the injection circuit can be opened and closed. The receiver adjusts the required refrigerant amount difference between the cooling operation and the heating operation, and the required refrigerant amount difference between the rated capacity operation (high load operation) and the intermediate capacity operation (low load operation).

1 and 2 show the flow of the refrigerant during the cooling operation. The refrigerant that has become high-temperature and high-pressure gas in the compressor 1 is heated by the four-way valve 2 in the heat source side heat exchanger (outdoor heat exchanger) 3
Head to. In the heat source side heat exchanger 3, the heat is radiated to the air to be blown (the blowing system is not shown), and the refrigerant is condensed to be in a gas-liquid two-phase, saturated liquid, or supercooled liquid refrigerant state. The determination of the state is controlled by the throttle amount of the first pressure reducing device 4. The refrigerant that has passed through the first depressurizing device 4 is depressurized into a gas-liquid two-phase state and flows into the receiver 5. The saturated liquid refrigerant or the gas-liquid two-phase refrigerant is taken out from the receiver 5, then passes through the blocking valve 6 and reaches the second pressure reducing device 7a. The second decompression device 7a becomes a gas-liquid two-phase refrigerant having a temperature lower than that of the room air, and flows into the use side heat exchanger (indoor heat exchanger) 8a. In the utilization side heat exchanger 6a, heat is absorbed from the indoor air that is blown (the blowing system is not shown), and the gas refrigerant returns to the compressor 1. The flow of the refrigerant during the heating operation is reversed by switching the four-way valve 2.

FIG. 1 shows the flow of the refrigerant in the injection circuit, and FIG. 2 shows the flow of the refrigerant in the bypass circuit. Figure 1
, The three-way valve 10 is switched to the injection circuit side, and the solenoid valve 1 on the injection circuit is
When 1 is open, the refrigerant is injected into the compression chamber of the compressor 1 during the compression process. At this time, the bypass circuit is closed. When the solenoid valve 12 is closed, the injection circuit is closed even if the three-way valve 10 is switched to the injection circuit side.

The injection method includes a receiver 5
There are two types depending on the state of the refrigerant to be taken out from the liquid, and when liquid or gas-liquid two-phase refrigerant is taken out and injected into the compressor 1, it becomes liquid injection, and when saturated gas refrigerant is taken out and injected into the compressor 1, it is gas injection. Becomes

Hereinafter, description will be made assuming that gas injection is performed. The driving force of gas injection is the pressure difference between the pressure of the compression chamber of the compressor 1 injected and the pressure of the receiver 5. Therefore, gas injection is performed when the pressure of the receiver 5 is higher than the pressure in the compression chamber of the compressor 1. As shown in FIG. 2, when the three-way valve 10 is switched to the bypass circuit, the compression chamber in the compression process of the compressor 1 and the suction side pipe 108 of the compressor 1 are connected, and the compression chamber of the compressor 1 Since the pressure is lower than the pressure in the suction side pipe 108 of the compressor 1, the refrigerant flows out (bypasses) from the compression chamber in the compression process of the compressor 1 to the suction side pipe 108 of the compressor 1. At this time, the injection circuit is closed.

The above air conditioner can select three operating methods for each of the cooling operation and the heating operation. 3 to 5, each operation will be described using a Mollier diagram. The horizontal axis of the Mollier diagram is enthalpy h,
The vertical axis represents the pressure p. Line 81 is a saturated liquid line and line 82 is a saturated gas line. The operation is shown as the cooling operation.

FIG. 3 shows a case where both the injection circuit and the bypass circuit are closed. Points P1 to P2 in the figure
Is a compressor 1, P2 to P3 are heat source side heat exchangers (outdoor heat exchangers) 3, P3 to P4 are first pressure reducing devices 4 to second pressure reducing devices 7a, and P4 to P1 are user side heat exchangers. The state of the refrigerant in (indoor heat exchanger) 8a is shown.
At this time, the mass flow rate G1 of the refrigerant is constant in the cycle.

FIG. 4 shows the case where the injection circuit is open and the bypass circuit is closed. Points P1 to P5 in the figure are the compression process (stage 1) of the compressor 1 until gas injection, and the refrigerant of the saturated gas of P11 is gas-injected into the compression chamber, resulting in the refrigerant state P6 of P5. The second compression process P6 to P7 starts. P7 to P3 are heat source side heat exchangers (outdoor heat exchangers) 3, P3 to P8 are the first pressure reducing device 4, P8 is the receiver 5, and P11 is the saturated gas refrigerant and P in the receiver.
The saturated liquid refrigerant of 9 coexists. In the main cycle, the refrigerant of the P9 saturated liquid is taken out from the receiver 5 and sent to the second pressure reducing device. P9 to P10 show the state of the refrigerant in the second pressure reducing device 7a, and P10 to P1 show the state of the refrigerant in the utilization side heat exchanger 8a. The mass flow rate of the refrigerant in the cycle is G at the heat source side heat exchanger.
2. G3 in the injection circuit, G in the user side heat exchanger
If it is 4, there is a relationship of G2 = G3 + G4. As a matter of course, in the compression process of the compressor 1, the flow rates of the refrigerant in the compression chamber before and after the injection are different from G4 and G2, respectively. Actually, the gas injection is performed by the receiver 5 and the compressor 1.
Since it is performed by the pressure difference between the compression chamber and the compression chamber, it is not instantaneously performed as in P6, but is sequentially performed over a certain time.

FIG. 5 shows the case where the injection circuit is closed and the gas bypass circuit is open. P1 to P2
Is the compressor 1, and the compression chamber having the pressure of P5 is the compressor 1
Since the suction side pipe is connected, the refrigerant flows out from the compression chamber to the suction side pipe of the compressor 1. Further, P2 to P3 are heat source side heat exchangers 3, P3 to P4 are first expansion valves to second expansion valves, and P4 to P12 are utilization side heat exchangers 8a (indoor heat exchangers). Therefore, when the mass flow rate of the refrigerant at the time of suction of the compressor 1 is G7 and the bypass flow rate is G6, the amount of refrigerant flowing in the cycle is G5 = G7-G5.

Based on FIG. 3, the coefficient of performance of the cycles of FIG. 4 and FIG. 5 (for example, during cooling operation: cooling COP = cooling capacity / power consumption) is compared. The cooling capacity is the product of the enthalpy difference of the utilization side heat exchanger (indoor heat exchanger (evaporator)) and the mass flow rate of the refrigerant. When gas injection is performed, the enthalpy difference in the use side heat exchanger is Δh (FIG. 4) = h (P1) −h (P10) in FIG. On the other hand, the enthalpy difference in FIG. 3 is Δh (FIG. 3) = h (P1) −h (P
4). Since the enthalpies of P1 and P3 are the same, Δh (FIG. 4)> Δh (FIG. 3), and if the capacities are the same, the gas flow rate may be smaller with gas injection (G4 <G1). Therefore, P1 to P5 of the compressor 1
The compression work during the period decreases, that is, the denominator of the coefficient of performance decreases and the coefficient of performance increases.

When bypassed (FIG. 5), the enthalpy difference of the heat exchanger on the use side does not change, but the mass flow rate of the refrigerant decreases (G5 = G7-G6: if the theoretical stroke volume of the compressor 1 is the same. G7 = G1), the ability can be reduced. Further, since the flow rate in the section from P5 to P2 of the compressor 1 is reduced, the compression work is reduced by this amount and the power consumption is also reduced. For example,
In the case of a compressor whose capacity is controlled by an inverter, the operating frequency of the compressor is changed according to the load, but if the capacity is large with respect to the load even if it reaches the minimum speed, useless work. become. At this time, if a bypass circuit is used, the capacity can be adjusted according to the load, and operation can be performed with a high coefficient of performance. Furthermore, when a constant speed compressor is used, capacity control cannot be performed by the compressor operating method, but by using a bypass circuit, capacity control becomes possible and operation at an operating point with high compressor efficiency becomes possible. Become.

Furthermore, regardless of whether the compressor is an inverter-driven compressor or a constant-speed compressor, the bypass circuit is opened to return the refrigerant to the compressor suction side, so that the heat source side heat exchanger (outdoor heat exchanger) can be used during cooling operation. ), The mass flow rate of the refrigerant flowing through
This is equivalent to an increase in the apparent heat exchanger, the condensing pressure decreases, and the compressor discharge pressure (Pd) decreases. Even in the use side heat exchanger (indoor heat exchanger), the refrigerant mass flow rate is reduced, so that the pressure loss is reduced, the evaporation pressure is increased, and the suction pressure (Ps) of the compressor can be increased. As a result, the pressure ratio (Pd /
Ps) becomes small, the compression work can be reduced, and the air conditioner can save energy.

Since three operation methods can be selected for both cooling and heating operations in the above cycle, the gas injection circuit has a pressure ratio (= Pd / Ps) between the compressor suction pressure (Ps) and the compressor discharge pressure (Pd). ) Is large, the bypass circuit is used when the pressure ratio is small. For example, J
Applying to the IS standard indoor and outdoor temperature conditions, the gas injection circuit should be used under overload conditions and rated conditions.
The bypass circuit is used under intermediate conditions. Usually, three optimal driving methods are selected based on preset and stored information according to each driving condition.

Specifically, the outdoor intake air temperature, the indoor intake air temperature, the set temperature set by the user and the operating frequency of the compressor are detected, and the data are stored in advance in a set value (for example, a program). , Table) and select the operation. The configuration of the control system is also shown in FIG. 1, in which a temperature sensor is provided on the suction side of the heat source side heat exchanger (outdoor heat exchanger) 3 to measure the outdoor temperature, and the use side heat exchanger (indoor heat exchanger) 8a A temperature sensor is installed on the suction side to measure the room temperature. A thermistor or a thermocouple is used for the temperature sensor.

A user inputs a set temperature from the remote controller 70 as an input device. In the case of inverter control, the compressor is provided with an operating frequency measuring sensor, and the operating frequency is obtained from a current waveform or a voltage waveform. Alternatively, the set frequency of the inverter may be used instead. The sensor and the input device (remote control) are connected to the controller 61,
This information is input to the controller 61. For example, information is transmitted to the controller 61 of the outdoor unit 21 via the indoor unit 22a.

A flow path switching valve (three-way valve) 10 for switching between an injection circuit and a bypass circuit and an opening / closing valve (solenoid valve) 11 for opening and closing the injection circuit are also connected to the controller 61. Data from the sensor and the input device is input to the controller 61, and the optimum operating method is selected from the three operating methods based on the determination value stored in advance, and the control signal is sent from the controller 61 to the three-way valve 10 or Control is transmitted to the solenoid valve 11. For example, when the temperature difference between the outdoor temperature and the indoor temperature is larger than the determination value and the temperature difference between the set temperature and the indoor temperature is also larger than the determination value, the injection circuit is opened. When the temperature difference between the outdoor temperature and the indoor temperature is smaller than the determination value and the temperature difference between the set temperature and the indoor temperature is smaller than the determination value, the bypass circuit is opened. Under other operating conditions, the bypass circuit and injection circuit are closed.

FIG. 6 shows the structure of the scroll compressor used in this embodiment and the injection circuit connected to the compression chamber. In the case of a scroll compressor, two compression chambers are formed at the same time. The compression chamber is formed by combining the wraps of the fixed scroll 42 and the orbiting scroll 43. Each compression chamber is provided with injection ports 47a and 47b at a predetermined pressure ratio. This port 47
It is easiest to provide a and 47b on the fixed scroll 42. The ports 47a and 47b are connected to the pipe 109 in FIG.

FIGS. 7 and 8 show a cycle structure of an air conditioner of another embodiment, which is basically shown in FIGS. 1 and 2.
It is the same as the cycle configuration shown in. FIG. 7 shows a case where a four-way valve 13 is used instead of the three-way valve 10 shown in FIGS. 1 and 2, and one of the four passages of the four-way valve is always closed. The operation is basically the same when the three-way valve 10 is used and when the four-way valve 13 is used. FIG. 8 shows a solenoid valve 14 instead of the three-way valve 10 shown in FIGS.
In this case, the solenoid valve 14 is provided between the capillary tube 13 on the pipe 110 and the connection point 19 of the injection circuit. Open the solenoid valve 11 and open the solenoid valve 1
When 4 is closed, the injection circuit can be used, and when the solenoid valve 11 is closed and the solenoid valve 14 is opened, the bypass circuit can be used. When both are closed, the normal cycle configuration is achieved.

FIG. 9 shows a cycle configuration according to another embodiment for performing gas injection, and the use of the gas injection circuit and the bypass circuit is the same as that of the air conditioner shown in FIGS. 1 and 2. . The cycle of FIG. 9 includes a compressor 1, a four-way valve 2, a heat source side heat exchanger 3,
The receiver 5, the blocking valve 6, the second pressure reducing device 7a, the use side heat exchanger 8a, the blocking valve 9, and the compressor 1 are sequentially connected by piping, and the refrigerant inlet port of the receiver 5 is used both during cooling operation and during heating operation. A flow control circuit 16 is provided at the entrance of the receiver 5 so as to be in one direction.

The flow control circuit 16 includes four check valves 14
A variable expansion electronic expansion valve is used as a, 14b, 14c, and 14d and the first pressure reducing device 4 to form a bridge circuit. Further, an injection circuit that connects the receiver 5 and the compressor 1 is provided, and a pipe 11 is provided from the receiver 5 side.
6, third pressure reducing device (injection pressure reducing device) 18,
The pipe 117, the pipe 111, the on-off valve 11, the pipe 112, and the pipe 109 are configured.

An intermediate heat exchanger 17 is provided downstream of the third pressure reducing device 18 for exchanging heat between the refrigerant downstream of the third pressure reducing device 18 and the refrigerant downstream of the receiver 5, and in the injection circuit. , The saturated liquid refrigerant is taken out from the receiver 5, and the pressure is reduced to an injection pressure by the third pressure reducing device 18 to form a gas-liquid two-phase refrigerant. Then, the intermediate heat exchanger 17 absorbs heat from the refrigerant on the downstream side of the third pressure reducing device 18 from the refrigerant on the downstream side of the mainstream receiver 5, and the gas-liquid two-phase refrigerant is completely gasified to perform intermediate compression of the compressor 1. Inject into the room. On the other hand, the mainstream refrigerant flow is a gas-liquid two-phase refrigerant state in which the saturated liquid refrigerant and the saturated gas refrigerant are taken out from the pipe 116 connected to the receiver 5, but the condensed refrigerant is condensed by the intermediate heat exchanger 17 and further cooled, It becomes a liquid refrigerant in a cooled state and flows to the use side heat exchange 8a. Outdoor unit 21 and indoor unit 2
When the connection pipe 105 and the pipe 106 connecting to the 2a are long pipes (for example, 30 m or more), the gas injection method in FIG. 9 is larger than that in FIG. 1 as a gas injection method. Become.

As described above, the injection circuit is provided with the bypass circuit connecting the injection circuit and the suction side pipe of the compressor, and by switching the circuits to use, the injection circuit is utilized to discharge the refrigerant from the compression chamber of the compressor. It is possible to control the capacity to flow out. Basically, the gas injection circuit is effectively used regardless of the presence or absence of the inverter control, and the capacity control in the direction of decreasing the capacity is enabled. As a result, the inverter control model enables capacity control that further reduces the capacity even at the lowest compressor operating frequency, and capacity control by increasing capacity by gas injection (energy saving improvement when capacity is constant). Is.

In the air conditioner equipped with the injection circuit, the circuit can be switched by adding one three-way valve, four-way valve or solenoid valve. Further, as the sensor used for operation control, information from an existing temperature sensor or the like which is generally held in the air conditioner may be used, and it is not necessary to newly install it. As a result, for example, when an inverter-driven compressor is used, the capacity can be further reduced, even if the operating frequency of the compressor is minimized. By creating the optimum operating condition, it becomes possible to operate the air conditioner in a state where the coefficient of performance is high. Also, when a constant speed compressor is used, if it does not adapt to the load, it causes the compressor to do extra work, but by using a bypass circuit, capacity control becomes possible and the air conditioner Driving with a high coefficient of performance becomes possible. Furthermore, since it is equipped with an injection circuit, if gas injection is performed, in the case of a compressor driven by an inverter, the operating frequency of the compressor can be reduced compared to the case without gas injection if the same capacity is used. Power consumption is reduced, resulting in energy-saving operation (high coefficient of performance). With a constant speed compressor,
If the stroke volume is the same, the capacity can be increased, and if the stroke capacity is the same, the stroke volume can be reduced, so that energy saving and size reduction of the compressor operation can be achieved.

Further, regardless of whether the compressor is an inverter-driven compressor or a constant-speed compressor, the bypass circuit is opened to return the refrigerant to the compressor suction side, so that the heat source side heat exchanger (outdoor heat exchanger) can be operated during the cooling operation. The mass flow rate of the flowing refrigerant is reduced, which is equivalent to the increase in the apparent heat exchanger, the condensing pressure is reduced, and the compressor discharge pressure (Pd) can be reduced. Even in the use side heat exchanger (indoor heat exchanger), the refrigerant mass flow rate is reduced, so that the pressure loss is reduced, the evaporation pressure is increased, and the suction pressure (Ps) of the compressor can be increased. Therefore, the pressure ratio (Pd / Ps) becomes small, and the compression work can be reduced.

By combining the injection circuit and the bypass circuit and selecting the operation method according to the conditions, the injection port can be effectively used, and the operation with a high coefficient of performance becomes possible in a wide operation range, and the operation of the air conditioner can be performed. It is possible to improve efficiency and save energy.

Further, the effect has been described by assuming that the compressor is driven by an inverter so that the operating frequency of the compressor can be changed and changed. However, in a compressor operated at a constant speed, the stroke volume (theoretical discharge volume) of the compressor is achieved by gas injection. Can be reduced, the load of the compressor is reduced accordingly, the electric input is reduced, and the required torque is reduced, so that the motor capacity can be reduced. Further, there is an effect that the casing of the compressor can be made smaller.

Further, by providing a bypass circuit utilizing a gas injection circuit, it becomes possible to perform stepwise capacity control even in a compressor operated at a constant speed. Further, in the injection method, it is possible to use liquid injection instead of gas injection, but the effect differs depending on the port position.

Further, although the compressor has been described as a scroll compressor, the same applies to a rotary compressor. Further, the refrigerant is R22, R410A, R32, R407.
Natural refrigerants such as C, carbon dioxide gas and HC refrigerant can also be used.

[0043]

As described above, according to the present invention, since the bypass circuit connecting the injection circuit and the suction side pipe of the compressor is provided in the injection circuit, the injection circuit is diverted from the compression chamber of the compressor. The capacity can be controlled by flowing out the refrigerant, and the pressure ratio (Pd / Ps), which is the ratio of the compressor suction pressure and the compressor discharge pressure, can be reduced by opening the bypass circuit and returning the refrigerant to the compressor suction side.

Therefore, it is possible to create an optimum operating condition adapted to the load, enable operation with a high coefficient of performance in a wide operating range, and improve the operating efficiency of the air conditioner.
Energy saving can be achieved.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an air conditioner according to an embodiment (gas injection circuit is open).

FIG. 2 is a system configuration diagram showing a state in which a bypass circuit is opened in FIG.

FIG. 3 is a Mollier diagram of the cycle operation of the air conditioner according to the embodiment when neither gas injection nor bypass is performed.

FIG. 4 is a Mollier diagram during gas injection of the air conditioner according to the embodiment.

FIG. 5 is a Mollier diagram when the air conditioner according to the embodiment is bypassed.

FIG. 6 is a cross-sectional view of a compressor according to one embodiment.

FIG. 7 is a system configuration diagram of an air conditioner according to another embodiment.

FIG. 8 is a system configuration diagram of an air conditioner according to another embodiment.

FIG. 9 is another system configuration diagram of the air conditioner that is an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Four-way valve, 3 ... Heat source side heat exchanger (outdoor heat exchanger), 4 ... 1st decompression device, 5 ... Receiver, 6 ... Blocking valve, 7a, 7b ... 2nd decompression device, 8a , 8b ... Utilization side heat exchanger (indoor heat exchanger), 9 ... Blocking valve, 10 ... Three-way valve,
11 ... Electromagnetic valve, 12 ... Capillary tube, 13 ... Four-way valve, 14 ... Electromagnetic valve, 44 ... Suction port, 45a, 45
b ... compression chamber, 46 ... discharge port, 47a, 47b ... injection port, 110 ... bypass piping, 111,
112 ... Injection piping.

Continued front page    (72) Inventor Yoshihiko Mochizuki             Hitachi, Ltd. 390 Muramatsu, Shimizu City, Shizuoka Prefecture             Air conditioning system Shimizu Production Headquarters (72) Inventor Kenji Matsumura             Hitachi, Ltd. 390 Muramatsu, Shimizu City, Shizuoka Prefecture             Air conditioning system Shimizu Production Headquarters F-term (reference) 3L060 AA03 CC02 CC03 CC19 DD01                       EE02 EE09

Claims (5)

[Claims] 1. A compressor, a heat source side heat exchanger, a first pressure reducing device,
A receiver, a second decompression device, in an air conditioner configured a refrigeration cycle by sequentially connecting the use side heat exchanger with piping, an injection circuit connected to the compression chamber of the compressor from the receiver, from the injection circuit An air conditioner comprising: a bypass circuit connected to a suction side pipe of a compressor. 2. The device according to claim 1, wherein a flow path switching valve is provided at a connection point between the injection circuit and the bypass circuit, and a connection of the injection circuit to the compression chamber is connected to the suction side pipe. Air conditioner characterized by switching to. 3. The air conditioner according to claim 1, further comprising a flow passage opening / closing valve provided between a connection point of the injection circuit and the bypass circuit and the receiver. 4. The air conditioner according to claim 1, wherein the bypass circuit is opened in association with an outdoor temperature and an indoor temperature. 5. The compressor according to claim 1, wherein the compressor is a variable displacement compressor whose operating frequency is controlled from a minimum frequency to a maximum frequency, and when the operating frequency is the minimum frequency, An air conditioner that does not perform injection by opening a bypass circuit.