JP2014102036A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner capable of sufficiently cooling a control unit as compared with a conventional air conditioner.SOLUTION: An air conditioner 1 includes: a main refrigerant circuit 13 configured so that refrigerant flows to a compressor 5, an outdoor heat exchanger 8, an expansion valve 9, and an indoor heat exchanger 4 in this order; and an injection circuit 14 branching off from between the outdoor heat exchanger 8 and the indoor heat exchanger 4 in the main refrigerant circuit 13 and returning the refrigerant at a pressure between a suction pressure and a discharge pressure to the compressor 5. The injection circuit 14 includes: an injection pressure reduction valve 15 reducing the pressure of the refrigerant; a control unit cooler 16 cooling a control unit for controlling the compressor 5 with the refrigerant; and a sub-cooler evaporation unit 17 that is provided downstream of the injection pressure reduction valve 15 and in which refrigerant heat exchange is made. The control unit cooler 16 is provided between the injection pressure reduction valve 15 and the sub-cooler evaporation unit 17 in the injection circuit 14.

Description

  The present invention relates to an air conditioner having a control unit cooling section that cools a control unit for controlling a compressor with a refrigerant.

  In a conventional refrigeration apparatus, a control unit cooling unit that cools a control unit for controlling a compressor with a refrigerant is installed in a main refrigerant circuit constituting a series of refrigeration cycles. For this reason, at the time of low differential pressure at the start of the refrigeration cycle, the flow rate of the refrigerant for cooling the control unit cannot be secured in the control unit cooling section, and the control unit is excessively heated. was there.

  Furthermore, in the conventional configuration in which the control unit cooling unit is provided in the main refrigerant circuit, the flow rate of refrigerant in the main refrigerant circuit has to be reduced due to oil forming or the like that causes a large amount of lubricating oil to be taken to the indoor unit. However, there is a problem that the cooling of the control unit becomes insufficient. For this reason, a method of cooling the control unit by installing a control unit cooling section in the main refrigerant circuit constituting a series of refrigeration cycles is not preferable.

  On the other hand, as a prior art aiming at improving the efficiency as a refrigeration cycle, a refrigeration apparatus by forming an injection circuit branched from the main refrigerant circuit has been already known separately from the main refrigerant circuit ( Patent Document 1). In the refrigeration apparatus described in Patent Document 1, an inverter cooling unit is provided as a control unit cooling unit in the injection circuit, and a part of the refrigerant diverted from the main refrigerant circuit flows into the inverter cooling unit via the expansion valve. And the inverter apparatus which is a kind of control unit is cooled with the refrigerant | coolant which flowed in (refer FIG. 1 of patent document 1).

JP 2010-2112

  However, with the technique disclosed in Patent Document 1, cooling of an inverter device, which is a kind of control unit, is insufficient, and a desired cooling efficiency cannot be obtained. This is because, in the refrigeration apparatus of Patent Document 1, the state of the refrigerant flowing into the inverter cooling unit cannot be maintained in a form suitable for cooling due to its configuration.

  Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide an air conditioner that can sufficiently cool the control unit as compared with the conventional art.

  That is, the air conditioner of the present invention includes a main refrigerant circuit configured such that refrigerant flows in order through a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger, and the outdoor heat in the main refrigerant circuit. An injection circuit that branches from between the exchanger and the indoor heat exchanger, and is configured to return the refrigerant that is at a pressure between the suction pressure and the discharge pressure to the compressor, and the injection circuit An injection pressure reducing valve for reducing the pressure of the refrigerant, a control unit cooling unit for cooling the control unit for controlling the compressor with the refrigerant, and a downstream side of the injection pressure reducing valve for heat exchange of the refrigerant. A sub-cooler evaporating unit, wherein the control unit cooling unit includes the injection pressure reducing valve in the injection circuit, and the sub-cooling unit. Characterized in that provided between the Ra evaporation section.

  If comprised in this way, since the said control unit cooling part is provided between the said injection pressure-reduction valve and the said subcooler evaporation part in the said injection circuit, it is connected to a control unit cooling part via an injection pressure-reduction valve. The supplied refrigerant can be brought into a liquid-rich state in which the refrigerant is hardly vaporized, and the control unit can be efficiently cooled by liquid cooling.

  In other words, compared with the case where the control unit is cooled using the refrigerant in a vaporized state as in Patent Document 1, the present invention improves the heat conduction efficiency from the control unit to the refrigerant, and as a result, The amount of heat per unit time that can be taken from the control unit can be increased, and the control unit can be efficiently cooled.

  Furthermore, in order to improve the compression efficiency of the compressor, it is preferable to flow the refrigerant into the compressor in a vaporized state as much as possible. In the present invention, as described above, the control is performed using the liquid-rich refrigerant. By cooling the unit, more heat can be taken from the control unit. As a result, the refrigerant can be vaporized more than before by heat exchange in the subcooler evaporator. Therefore, the refrigerant in a vaporized state than before can be caused to flow into the compressor. As a result, the present invention has the effect of improving the compression efficiency of the compressor as well as efficient cooling of the control unit.

  In addition, as a further effect of being able to increase the cooling efficiency of the control unit, the required cooling efficiency can be obtained even if the control unit cooling section is downsized and the heat radiation area is reduced compared to the conventional one. Miniaturization can be achieved.

  In order to obtain the effect that the temperature of the refrigerant in the control unit cooling unit can be freely adjusted by design by appropriately adjusting design parameters such as the diameter of the throttle pipe, the injection circuit includes the control unit cooling unit and the control unit cooling unit. It is preferable to further include a throttle pipe provided between the sub-cooler evaporators.

  In order to prevent the temperature of the control unit from becoming lower than the dew point temperature, and to obtain an effect of more reliably preventing the control unit from causing condensation and causing the control unit to fail, the air conditioner is An outside air temperature sensor capable of detecting the outside air temperature, a control unit temperature detector capable of detecting the temperature of the control unit, and a dew point temperature calculation for calculating a dew point temperature at which dew condensation occurs in the control unit based on the outside air temperature And an opening degree adjusting part for adjusting the opening degree of the injection pressure reducing valve so that the temperature of the control unit is equal to or higher than the dew point temperature.

  Thus, according to the air conditioner of the present invention, the control unit cooling section is provided between the injection pressure reducing valve and the subcooler evaporation section in the injection circuit. It can be supplied to the control unit cooling section via a valve. Thereby, in the control unit cooling section, the control unit can be cooled using the liquid-rich refrigerant in which the vaporization has not progressed so much. Therefore, the amount of heat per unit time that can be taken from the control unit can be increased as compared with the case where the control unit is cooled using the refrigerant in the vaporized state, and as a result, the cooling efficiency of the control unit can be improved.

  Furthermore, according to the air conditioner of the present invention, by cooling the control unit using the liquid-rich refrigerant, more heat can be taken from the control unit. The refrigerant can be vaporized more than before by replacement. Therefore, it is possible to allow the refrigerant in a vaporized state to flow into the compressor more than before, and there is an effect that not only efficient control unit cooling but also compression efficiency of the compressor can be improved.

  According to the air conditioner of the present invention, the cooling efficiency required even if the control unit cooling part is downsized and the heat radiation area is reduced as compared with the prior art, as a further effect of being able to increase the cooling efficiency of the control unit. The outdoor unit can be downsized.

It is a figure which shows the structural example of the air conditioner shown as 1st Embodiment of this invention. It is the figure which showed the refrigerant cycle in the air conditioner which concerns on 1st Embodiment of this invention. It is the figure which showed the relationship between IPM temperature [degreeC] and condensation temperature [degreeC]. It is a figure which shows the structural example of the air conditioner shown as 2nd Embodiment of this invention. It is the figure which showed the refrigerant cycle in the air conditioner which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the structure of the control part which concerns on 3rd Embodiment of this invention. It is the flowchart which showed an example of the dew condensation avoidance control operation | movement in 3rd Embodiment of this invention.

[First Embodiment]
Hereinafter, the air conditioner 1 which concerns on 1st Embodiment of this invention is demonstrated, referring FIGS. 1-3.

[Configuration of air conditioner 1]
FIG. 1 shows a configuration example of an air conditioner 1 shown as the first embodiment of the present invention. The air conditioner 1 is an air conditioner 1 including an inverter circuit cooling unit (control unit cooling unit) 16 capable of cooling an inverter circuit C (control unit) for inverter-controlling the compressor 5 with a refrigerant, As shown in FIG. 1, an indoor unit 2 and an outdoor unit 3 are provided.

  The indoor unit 2 includes an indoor heat exchanger 4, a room temperature sensor (not shown) that can detect the room temperature in the room, a remote controller (not shown) that can control the indoor unit 2 in accordance with a user operation, and the like. Have.

  The outdoor unit 3 includes a compressor 5, a four-way switching valve 6, an outdoor fan 7, an outdoor heat exchanger 8, an expansion valve 9, an outdoor air temperature sensor 10 that can detect the outdoor air temperature, an accumulator 11, And a control unit 12. The accumulator 11 is for gas-liquid separation of the refrigerant flowing in, and is disposed between the compressor 5 and the four-way switching valve 6. The control unit 12 is configured to be able to control the refrigerant discharge amount of the compressor 5, the opening degree of the expansion valve 9, and the like based on detection information from each temperature sensor.

  The air conditioner 1 has a main refrigerant circuit 13 and an injection circuit 14. The main refrigerant circuit 13 is a circuit configured so that refrigerant flows through the compressor 5, the outdoor heat exchanger 8, the expansion valve 9, and the indoor heat exchanger 4 in order. The injection circuit 14 is configured to branch from between the outdoor heat exchanger 8 and the indoor heat exchanger 4 in the main refrigerant circuit 13 and return the refrigerant having a pressure between the suction pressure and the discharge pressure to the compressor 5. Circuit.

  The injection circuit 14 has an injection pipe 18 (a pipe indicated by a thick line in FIG. 1) configured to branch from between the outdoor heat exchanger 8 and the indoor heat exchanger 4 and return to the compressor 5. The injection pressure reducing valve 15 provided on the injection pipe 18, the inverter circuit cooling unit 16, and the subcooler evaporation unit 17 are provided. In other words, the inverter circuit cooling unit 16 is provided between the injection pressure reducing valve 15 and the subcooler evaporation unit 17 and is located upstream of the subcooler evaporation unit 17, so The refrigerant in the state flows into the inverter circuit cooling unit 16.

  The injection pressure reducing valve 15 is configured to be able to reduce the pressure of the refrigerant by adjusting its opening. The inverter circuit cooling unit 16 is provided between the injection pressure reducing valve 15 and the subcooler evaporation unit 17 in the injection circuit 14.

  The inverter circuit cooling unit 16 has a contact part 16a that contacts the inverter circuit C and a cooling pipe 16b that meanders inside the contact part 16a, and cools the inverter circuit C by the refrigerant flowing through the cooling pipe 16b. It is configured to be possible.

  The subcooler evaporation unit 17 is provided on the downstream side of the injection pressure reducing valve 15 and the inverter circuit cooling unit 16. The subcooler evaporator 17 is configured such that heat exchange is performed between the refrigerant flowing through the injection pipe 18 and the refrigerant flowing through the main refrigerant circuit 13. The refrigerant flowing through the injection pipe 18 in the subcooler evaporation unit 17 absorbs heat from the refrigerant flowing through the main refrigerant circuit 13 and evaporates. Then, the evaporated and vaporized refrigerant is returned to the compressor 5 at a pressure between the suction pressure and the discharge pressure.

[Flow of refrigerant in air conditioner 1]
Next, the operation of the air conditioner 1 will be described with reference to the PH (pressure-enthalpy) diagram of FIG. 2 regarding the refrigerant flow in the air conditioner 1 according to the present embodiment. In the air conditioner 1, either the cooling operation or the heating operation can be realized by switching the four-way switching valve 6. Here, the refrigerant flow during the cooling operation will be described.

  First, the refrigerant is compressed in the compressor 5 through the suction pressure P1 to the pressure P3 (pressure between the suction pressure P1 and the discharge pressure P2) until the discharge pressure P2 is reached (A → in FIG. 2). G → B). The refrigerant discharged from the compressor 5 (in this embodiment, the refrigerant temperature: 50 [° C.]) flows through the outdoor heat exchanger 8 after passing through the four-way switching valve 6. In the outdoor heat exchanger 8, the refrigerant is condensed and liquefied by heat radiation to the outdoor air (B → C in FIG. 2). Next, the liquefied refrigerant is divided between the outdoor heat exchanger 8 and the indoor heat exchanger 4, and a part of the refrigerant is changed from the discharge pressure P2 to the suction pressure P1 before being supplied to the indoor heat exchanger 4. The pressure is reduced until the gas is in a vapor-liquid equilibrium state (C → D in FIG. 2). A part of the refrigerant in the gas-liquid equilibrium state is supplied to the indoor heat exchanger 4. In the indoor heat exchanger 4, a part of the refrigerant absorbs heat from the indoor air and evaporates. Thereby, indoor air is cooled. A part of the evaporated refrigerant is sucked into the suction side of the compressor 5 at the suction pressure P1 and compressed again (D → A in FIG. 2).

  On the other hand, the refrigerant that has been branched downstream of the outdoor heat exchanger 8 is reduced in pressure from the discharge pressure P2 to the pressure P3 in the injection pressure reducing valve 15 to reach a liquid-rich gas-liquid equilibrium state (C → in FIG. 2). E). The reduced-pressure liquid-rich refrigerant (in this embodiment, refrigerant temperature: 20 [° C.]) is supplied to the inverter circuit cooling unit 16. That is, the inverter circuit cooling unit 16 cools the inverter circuit C using the refrigerant that is in a liquid-rich state. And after cooling of this inverter circuit C, a refrigerant | coolant is supplied to the subcooler evaporation part 17 (a part of E-> F in FIG. 2). In the subcooler evaporation unit 17, the remaining refrigerant evaporates by heat exchange. Then, the intermediate-pressure refrigerant evaporated by evaporation again flows into the compressor 5 at the pressure P3 (F → G in FIG. 2).

  Next, the present invention will be specifically described with reference to FIG. Here, the result of examining the usefulness of the air conditioner 1 according to the present embodiment based on the relationship between the IPM (inverter power module) temperature [° C.] and the condensation temperature [° C.] in the condenser will be described. In addition, this invention is not limited to a present Example. More specifically, the present inventor provides an IPM cooling method for cooling an IPM (corresponding to the inverter circuit C in the embodiment) by providing an inverter circuit cooling unit 16 for the injection circuit 14 according to the present embodiment; The usefulness of the air conditioner 1 according to the present embodiment was examined by comparison with an IPM cooling method using a conventional method by providing an inverter cooling unit in the main refrigerant circuit.

  FIG. 3 shows the relationship between the IPM temperature [° C.] and the condensation temperature [° C.] in the condenser. As shown in FIG. 3, in the conventional system in which the inverter cooling unit is provided in the main refrigerant circuit, the IPM temperature [° C.] changes in proportion to the load condition (condensation temperature [° C.]). The temperature could not be kept constant (in the present example, around 80 [° C.]). Therefore, in the conventional system in which the inverter cooling unit is provided in the main refrigerant circuit, when the condensation temperature [° C.] decreases, the IPM temperature [° C.] decreases accordingly, and the IPM is cooled at a temperature lower than the outside air temperature. May end up. In this case, as a result of the IPM temperature becoming lower than the outside air temperature, dew condensation occurs in the IPM, leading to a situation where the IPM fails.

  Conventionally, under the high outside air condition of cooling where the load (condensation temperature) is high, the temperature of the IPM also rises according to the operating state, so the cooling of the IPM has become severe. For this reason, it is necessary to design the air conditioner in accordance with the high pressure rise characteristics. When severe conditions are set as design points, there is a problem that condensation occurs in the IPM under low load conditions where the condensation temperature is low.

  In contrast, in the IPM cooling method using the injection circuit 14 according to the present embodiment, even when the load condition (condensation temperature [° C.]) changes, the IPM temperature is stabilized (80 [ In the present embodiment, the IPM temperature becomes lower than the outside air temperature, as in the case of using a method in which an inverter cooling unit is provided in the conventional main refrigerant circuit, It can be prevented that condensation occurs in the IPM and the IPM breaks down. Moreover, compared with the case where the system which provided the inverter cooling part in the conventional main refrigerant circuit is used, a present Example is simple design. Furthermore, by changing the cooling area in the inverter circuit cooling unit 16, the IPM temperature can be easily managed, and the IPM temperature can be easily designed within the dew condensation avoiding temperature.

[Characteristics of the air conditioner in the first embodiment]
According to the above configuration, since the inverter circuit cooling unit 16 is provided between the injection pressure reducing valve 15 and the subcooler evaporator 17 in the injection circuit 14, the liquid-rich refrigerant is supplied to the injection pressure reducing valve 15. To the inverter circuit cooling unit 16. Thereby, in the inverter circuit cooling unit 16, the inverter circuit C can be cooled using the liquid-rich refrigerant that is hardly vaporized. Therefore, as compared with the case where the inverter circuit C is cooled by using the vaporized refrigerant, the amount of heat that can be taken from the inverter circuit C can be increased. As a result, the cooling efficiency of the inverter circuit C can be improved.

  Therefore, according to the above configuration, by cooling the inverter circuit C using the liquid-rich refrigerant, more heat can be taken from the inverter circuit C. As a result, heat exchange in the subcooler evaporation unit 17 is achieved. Thus, the refrigerant can be vaporized more than before and can flow into the compressor 5. Thereby, in the said structure, not only efficient cooling of the inverter circuit C but the effect that the compression efficiency of the compressor 5 can be improved is also show | played.

  Furthermore, according to the above configuration, as a further effect of being able to increase the cooling efficiency of the inverter circuit C, the required cooling efficiency can be obtained even if the inverter circuit cooling unit 16 is downsized and the heat radiation area is reduced as compared with the conventional case. Therefore, the outdoor unit 3 can be downsized.

  Further, in the conventional system in which the inverter cooling unit is provided in the main refrigerant circuit, because there is a request from the air conditioning side, the air conditioning temperature control is given priority. As a result, the control focusing on the cooling of the inverter circuit C cannot be executed. There has been a problem that the refrigerant temperature cannot be set to be suitable for cooling the inverter circuit C. On the other hand, according to the said structure, by providing the inverter circuit cooling part 16 in the injection circuit 14, without interfering with the refrigerant control regarding the air conditioning control which is the main objective of the air conditioner 1, by the refrigerant control in the injection circuit 14 It is possible to set the refrigerant temperature suitable for cooling the inverter circuit C.

  In addition, in the conventional method by providing an inverter cooling part in the main refrigerant circuit, when the temperature of the inverter circuit C becomes equal to or lower than the dew point temperature, the temperature of the inverter circuit C is raised to cause dew condensation generated in the inverter circuit C. In order to avoid this, there was only a countermeasure that has a great influence on the basic performance of the product, such as lowering the frequency of the compressor. On the other hand, according to the above configuration, by providing the inverter circuit cooling unit 16 in the injection circuit 14, the flow rate of the refrigerant can be controlled by the injection circuit 14 itself independently of the main refrigerant circuit 13. It is possible to suppress a decrease in basic performance of the. For example, it is possible to avoid the inverter circuit C from becoming the dew point temperature or less by realizing the flow control of the refrigerant by the opening / closing operation of the injection pressure reducing valve 15.

[Second Embodiment]
Next, the air conditioner 1 which concerns on 2nd Embodiment of this invention is demonstrated, referring FIG.4 and FIG.5. In addition, about the element same as the element demonstrated in 1st Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted. This embodiment is different from the first embodiment in that the injection circuit 14 includes a throttle pipe 19.

[Configuration of Injection Circuit 14]
As shown in FIG. 4, the injection circuit 14 includes an injection pipe 18 (bold line in FIG. 4) configured to branch from the outdoor heat exchanger 8 and the indoor heat exchanger 4 and return to the compressor 5. And an injection pressure reducing valve 15 provided on the injection pipe 18, an inverter circuit cooling unit 16, a subcooler evaporation unit 17, and a throttle pipe 19. The throttle pipe 19 is provided between the inverter circuit cooling unit 16 and the subcooler evaporation unit 17.

[Flow of refrigerant in air conditioner 1]
Next, the flow of the refrigerant in the air conditioner 1 according to the present embodiment will be described with reference to the PH (pressure-enthalpy) diagram of FIG. In the air conditioner 1, either the cooling operation or the heating operation can be realized by switching the four-way switching valve 6. Here, the refrigerant flow during the cooling operation will be described. Here, the opening of the expansion valve 9 is in a fully open state.

  The refrigerant divided between the outdoor heat exchanger 8 and the indoor heat exchanger 4 is reduced in pressure from the discharge pressure P2 to the pressure P4 in the injection pressure reducing valve 15 to be in a liquid-rich gas-liquid equilibrium state (FIG. 5). Middle C → E). Then, the decompressed liquid-rich refrigerant is supplied to the inverter circuit cooling unit 16. In the inverter circuit cooling section 16, the inverter circuit C is cooled using a liquid-rich refrigerant (in this embodiment, 20 [° C.] <Refrigerant temperature <50 [° C.]) (in FIG. 5). E → F). Then, after this cooling, the refrigerant is supplied to the throttle pipe 19. In the throttle pipe 19, the refrigerant is depressurized until the pressure P4 changes to the pressure P3 (F → G in FIG. 5). Then, the decompressed refrigerant (refrigerant temperature: 20 [° C.] in the present embodiment) is supplied to the subcooler evaporation unit 17 (G → H in FIG. 5). In the subcooler evaporation unit 17, the refrigerant evaporates by heat exchange. Then, the refrigerant evaporated by evaporation flows again into the compressor 5 at the pressure P3 (H → I in FIG. 5).

[Characteristics of the air conditioner in the second embodiment]
According to the said structure, the effect similar to the air conditioner 1 in 1st Embodiment can be acquired.

  Furthermore, according to the above configuration, the injection circuit 14 further includes the throttle pipe 19 provided between the inverter circuit cooling unit 16 and the sub-cooler evaporator 17, so that design parameters such as the diameter of the throttle pipe 19 can be appropriately set. By adjusting, the temperature of the refrigerant in the inverter circuit cooling unit 16 (in this embodiment, 20 [° C.] <Refrigerant temperature <50 [° C.]) can be freely adjusted in design.

[Third Embodiment]
Next, the air conditioner 1 which concerns on 3rd Embodiment of this invention is demonstrated, referring FIG.6 and FIG.7. In addition, about the element same as the element demonstrated in 1st Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted. This embodiment is different from the first embodiment in that the control unit 12 includes an inverter circuit temperature detection unit (control unit temperature detection unit) 20, a dew point temperature calculation unit 21, and an opening degree adjustment unit 22. .

[Configuration of Control Unit 12]
FIG. 6 is a block diagram showing a configuration of the control unit 12 according to the third embodiment of the present invention. As shown in FIG. 6, the control unit 12 includes an inverter circuit temperature detection unit 20, a dew point temperature calculation unit 21, and an opening degree adjustment unit 22. The inverter circuit temperature detection unit 20 is configured to be able to detect the temperature of the inverter circuit (control unit). The dew point temperature calculation unit 21 is configured to be able to calculate the dew point temperature at which dew condensation occurs in the inverter circuit C based on the outside air temperature detected by the outside air temperature sensor 10. The opening degree adjusting unit 22 is configured to be able to adjust the opening degree of the injection pressure reducing valve 15 so that the temperature of the inverter circuit C becomes equal to or higher than the dew point temperature.

[Condensation avoidance control operation of inverter circuit C in this embodiment]
Hereinafter, an example of the dew condensation avoidance control operation of the inverter circuit C in the present embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing an example of the condensation avoidance control operation in the present embodiment. Each operation shown in FIG. 7 can be realized by the control unit 12 executing a program stored in the ROM.

  First, in step S1, the inverter circuit temperature detection unit 20 detects the temperature of the inverter circuit C. Then, the process proceeds to step S2.

  Next, in step S <b> 2, the dew point temperature calculation unit 21 calculates the dew point temperature at which dew condensation occurs in the inverter circuit C based on the outside air temperature detected by the outside air temperature sensor 10. Then, the process proceeds to step S3.

  Finally, in step S3, the opening degree adjusting unit 22 adjusts the opening degree of the injection pressure reducing valve 15 so that the temperature of the inverter circuit C becomes equal to or higher than the dew point temperature. Thereby, the dew condensation avoidance control operation of the inverter circuit C in this embodiment is completed.

[Characteristics of the air conditioner in the third embodiment]
According to the said structure, the effect similar to the air conditioner 1 in 1st Embodiment can be acquired.

  Further, according to the above configuration, the opening degree adjusting unit 22 adjusts the opening degree of the injection pressure reducing valve 15 so that the temperature of the inverter circuit C becomes equal to or higher than the dew point temperature. Therefore, it is possible to more reliably prevent the inverter circuit C from failing and causing the inverter circuit C to fail.

  As mentioned above, although embodiment of this invention was described based on drawing, it should be thought that a specific structure is not limited to these embodiment. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  In each of the above embodiments, as an example of the control unit, an example in which an inverter circuit for inverter-controlling the compressor is cooled using the inverter circuit cooling unit of the injection circuit has been described, but the present invention is not limited thereto. In addition to the inverter circuit, various control units for controlling the compressor may be cooled using a control unit cooling unit of the injection circuit.

  In the third embodiment, an example in which the dew point temperature calculation unit 21 calculates the dew point temperature at which condensation occurs in the inverter circuit based on the outside temperature detected by the outside temperature sensor 10 has been described. The dew point temperature calculation unit 21 may calculate the dew point temperature at which dew condensation occurs in the inverter circuit based on the outside air temperature and humidity. Thereby, compared with the case where dew point temperature is calculated only based on outside temperature, calculation of dew point temperature can be performed correctly.

  In each of the above embodiments, the example in which the present invention is applied to the cooling of the inverter circuit has been described. However, in addition to the inverter circuit, if the control unit controls the compressor and requires cooling, the present invention can be used. The invention can be applied.

DESCRIPTION OF SYMBOLS 1 Air conditioner 2 Indoor unit 3 Outdoor unit 4 Indoor heat exchanger 5 Compressor 6 Four-way switching valve 7 Outdoor fan 8 Outdoor heat exchanger 9 Expansion valve 10 Outside air temperature sensor 11 Accumulator 12 Control part 13 Main refrigerant circuit 14 Injection circuit 15 Injection pressure reducing valve 16 Inverter circuit cooling section (control unit cooling section)
17 Subcooler evaporator 18 Injection pipe 19 Throttle pipe 20 Inverter circuit temperature detector (control unit temperature detector)
21 Dew point temperature calculation unit 22 Opening adjustment unit

Claims (3)

A main refrigerant circuit configured such that the refrigerant flows in order through the compressor, the outdoor heat exchanger, the expansion valve, and the indoor heat exchanger;
An injection circuit configured to branch from between the outdoor heat exchanger and the indoor heat exchanger in the main refrigerant circuit and to return the refrigerant having a pressure between the suction pressure and the discharge pressure to the compressor. With
The injection circuit is
An injection pressure reducing valve for reducing the pressure of the refrigerant;
A control unit cooling section that cools a control unit for controlling the compressor with a refrigerant;
A subcooler evaporating unit that is provided downstream of the injection pressure reducing valve and performs heat exchange of the refrigerant,
The air conditioner characterized in that the control unit cooling section is provided between the injection pressure reducing valve and the subcooler evaporation section in the injection circuit. The injection circuit is
The air conditioner according to claim 1, further comprising a throttle pipe provided between the control unit cooling unit and the sub-cooler evaporation unit. An outside temperature sensor capable of detecting the outside temperature;
A control unit temperature detector capable of detecting the temperature of the control unit;
A dew point temperature calculation unit for calculating a dew point temperature at which dew condensation occurs in the control unit based on the outside air temperature;
An opening degree adjusting unit for adjusting the opening degree of the injection pressure reducing valve so that the temperature of the control unit is equal to or higher than the dew point temperature;
The air conditioner according to claim 1 or 2, further comprising: