JP2019148417A - Air conditioner - Google Patents

Abstract

To provide an air conditioner capable of suppressing dew formation on a heat generating body and its peripheral portion.SOLUTION: An air conditioner (1) includes: a main refrigerant circuit (4) in which a compressor (11), a heat source side heat exchanger (13), a first expansion valve (15) and a use side heat exchanger (16) are provided and a refrigerant flows; an auxiliary refrigerant circuit (5) including a cooling member (41) in which the refrigerant branched from the main refrigerant circuit (4) flows and having the refrigerant branched from the main refrigerant circuit (4) and flowing therein; and a heat generating body (31) cooled by the cooling member (41). Piping (6) for causing part of the refrigerant discharged from the compressor (11) to flow is connected to piping (5) between the cooling member (41) and a second expansion valve (43) provided in the auxiliary refrigerant circuit (5) and expanding the refrigerant flowing to the cooling member (41).SELECTED DRAWING: Figure 7

Description

  The present invention relates to an air conditioner.

  Conventionally, in an air conditioner that performs a vapor compression refrigeration cycle by circulating a refrigerant, an electric circuit such as an inverter circuit that controls the rotational speed of the compressor is mounted in order to control the operation state of the compressor. In general, a power element that generates high heat by controlling or supplying power is used for an inverter circuit.

  In the conventional air conditioner, means for cooling the power element is provided so that the temperature does not become higher than the temperature at which the power element can operate. As an example of this cooling means, a refrigerant cooling technique for cooling a power element with a refrigerant flowing through a refrigerant circuit is proposed.

  In Patent Document 1, “a main refrigerant circuit (11) including a compressor (32), a heat source side heat exchanger (30), a first expansion valve (34), and a use side heat exchanger (20) through which refrigerant flows”. , “A branched refrigerant circuit (12) through which a refrigerant branched from the main refrigerant circuit (11) flows”, and “a refrigerant that is provided in the branched refrigerant circuit (12) and flows to the cooling unit (53). By further including a second expansion valve (61, 62) to be expanded and a control unit (60) for controlling the second expansion valve (61, 62), "the cooling capacity of the cooling unit (53) is improved. It can be controlled and the temperature of the electrical components (50a to 50d) (attached FIG. 4) can be adjusted appropriately ”.

  In Patent Document 2, “a plurality of compressors (23A, 23B) are provided, and a power board (35A, 35B) and a cooling unit (37A, 37B) are provided for each compressor (23A, 23B). In this case, depending on the operation or performance of the compressors (23A, 23B), the refrigerant adjustment mechanism has a cooling unit (37A) corresponding to the power board (35A, 35B) of the compressors (23A, 23B). , 37B) ”, it is possible to“ cool the electrical components (35A, 35B) with the refrigerant flowing through the refrigerant circuit (18) more efficiently ”. Has been.

Japanese Laid-Open Patent Publication No. 2006-170469 (Fig. 1, Fig. 4 etc.) JP 2011-117677 A (FIG. 1 etc.)

  By the way, if the temperature of the coolant that cools the power element becomes too low, the temperature of the surface of the power element and its peripheral part becomes lower than the dew point temperature of the ambient air, and condensation may occur on the surface of the power element and its peripheral part. There is.

  However, when the plurality of power elements are cooled by the structure disclosed in Patent Document 2, that is, the cooling unit, the power element corresponding to the operating compressor generates heat, while the power corresponding to the stopped compressor is generated. The element does not generate heat. Even in such a case, since all the power elements are cooled by the cooling unit, the power element corresponding to the stopped compressor and its peripheral part may be below the dew point, and condensation may occur.

  Further, even when the structure disclosed in Patent Document 1, that is, when the cooling capacity of the cooling unit is controlled by providing an expansion valve in the branch refrigerant circuit, all the power elements are cooled by the cooling unit. The power element corresponding to the compressor of the compressor and its peripheral part may be below the dew point, and condensation may occur.

  The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide an air conditioner that can suppress the occurrence of dew condensation in the heating element and its surroundings.

  In order to solve the above problems, an air conditioner according to a first aspect of the present invention includes a main refrigerant circuit in which a compressor, a heat source side heat exchanger, a first expansion valve, and a use side heat exchanger are provided, and the refrigerant flows; A cooling member through which a refrigerant branched from the main refrigerant circuit flows is provided, and includes a sub refrigerant circuit through which the refrigerant branched from the main refrigerant circuit flows, and a heating element cooled by the cooling member, and is discharged from the compressor. A pipe through which a part of the refrigerant flows is connected to a pipe between the cooling member and a second expansion valve that is provided in the sub refrigerant circuit and expands the refrigerant flowing to the cooling member.

  The air conditioner of the second aspect of the present invention is provided with a compressor, a heat source side heat exchanger, a first expansion valve and a use side heat exchanger, and is branched from a main refrigerant circuit through which a refrigerant flows and the main refrigerant circuit A cooling member through which a refrigerant flows is provided, a sub refrigerant circuit through which the refrigerant branched from the main refrigerant circuit flows, a heating element cooled by the cooling member, and a sub refrigerant circuit provided in parallel to the cooling member. A pipe that is connected to a pipe that is provided and flows a part of the refrigerant discharged from the compressor to the pipe that is provided in the cooling member, and a pipe that passes the refrigerant that has passed through the pipe provided to the cooling member to the main refrigerant circuit And.

  According to the present invention, in an air conditioner including a cooler that cools a plurality of heating elements with a refrigerant flowing in a refrigerant circuit, dew condensation is generated in the heating element corresponding to the stopped device among the plurality of heating elements and its peripheral portion. It can be suppressed from occurring.

The figure which shows the refrigerating cycle of the air conditioner which concerns on 1st Embodiment. The figure which shows the case where the heat source side heat exchanger which concerns on 1st Embodiment is a heat exchanger which heat-exchanges between water and a refrigerant | coolant. The front view of a part of inverter device. The A direction arrow directional view of a part of inverter apparatus. The figure which shows the control system of an air conditioner. The figure which shows the control flow of the air conditioner of 1st Embodiment. The figure which shows the control flowchart of the air conditioner of 2nd Embodiment. The figure which shows an example of the refrigerating cycle of the air conditioner which concerns on 3rd Embodiment. The figure which shows the other examples of the refrigerating cycle of the air conditioner which concerns on 3rd Embodiment. The figure which shows an example of the refrigerating cycle of the air conditioner which concerns on 4th Embodiment. Schematic which shows the modification 1 of the cooling member of 1st Embodiment. Schematic which shows the modification 2 of the cooling member of 1st Embodiment. Schematic which shows the modification 3 of the cooling member of 1st Embodiment. Schematic which shows the modification 4 of the cooling member of 1st Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the term “refrigerant or refrigeration cycle” refers to a refrigerant or refrigeration cycle that can be used for cooling and / or heating.

<< First Embodiment >>
Drawing 1A is a figure showing the refrigerating cycle of air harmony machine 1 concerning a 1st embodiment. Drawing 1B is a figure showing the case where heat source side heat exchanger 13 concerning a 1st embodiment is a heat exchanger which exchanges heat between water and a refrigerant.

  The air conditioner 1 according to the first embodiment shown in FIG. 1A includes a heat source unit 2 (for example, an outdoor unit) that supplies heat and a use unit 3 (for example, an indoor unit) that performs cooling and heating using the heat. It is configured. The heat source unit 2 and the utilization unit 3 are connected via refrigerant pipes 1L and 1V. The number of heat source units 2 and utilization units 3 is not limited to one each, and may be a plurality.

The utilization unit 3 includes a utilization side expansion valve 17, a utilization side heat exchanger 16, and a blower 18 that are decompression devices on the utilization unit 3 side. The blower 18 sends air to the use side heat exchanger 16 in order to promote heat exchange with the air of the use side heat exchanger 16.
The heat source unit 2 includes a main refrigerant circuit 4, a branch refrigerant circuit (sub refrigerant circuit) 5, and a discharge gas branch refrigerant circuit (pipe) 6.

The main refrigerant circuit 4 is a main circuit for the air conditioner 1 to perform air conditioning and the like.
The branch refrigerant circuit 5 is a circuit through which a low-temperature refrigerant flows in order to cool the power elements (heating elements) 31 and 32 used for controlling the air conditioner 1.
The discharge gas branch refrigerant circuit 6 is a circuit through which a high-temperature refrigerant flows in order to suppress dew of the power elements 31 and 32.

<Main refrigerant circuit 4>
The main refrigerant circuit 4 is a circuit to which main components of the heat source unit 2 are connected.
The main refrigerant circuit 4 includes a first compressor 11, a second compressor 12, a four-way valve 20, a gas-side shut-off valve 21, and a liquid-side shut-off valve that play a role of switching the refrigerant flow direction during cooling operation and heating operation. 22, a heat source side heat exchanger 13, and a first expansion valve 15 that is a pressure reducing device on the heat source unit 2 side.

Here, when the heat source side heat exchanger 13 is a heat exchanger that exchanges heat between air and the refrigerant flowing through the main refrigerant circuit 4, the heat source unit 2 exchanges heat with the heat source side heat exchanger 13. It includes a blower 14 that feeds air to facilitate.
In addition, as shown to FIG. 1B, when the heat source side heat exchanger 13 is a heat exchanger which performs heat exchange between water and a refrigerant | coolant, the air blower 14 can be abbreviate | omitted.

<Cooling operation>
In the cooling operation of the air conditioner 1, the refrigerant discharged from the first and second compressors 11 and 12 flows into the heat source side heat exchanger 13 through the four-way valve 20, and dissipates heat to air or water by heat exchange. And condensed. The high-pressure gas refrigerant discharged from the first and second compressors 11 and 12 becomes high-pressure liquid refrigerant by heat exchange in the heat source side heat exchanger 13. The high-pressure liquid refrigerant is depressurized according to the opening degree of the first expansion valve 15 when passing through the first expansion valve 15.

  That is, if the opening degree of the first expansion valve 15 is large, the pressure is reduced less. If the opening degree of the first expansion valve 15 is small, the pressure is greatly reduced. During the cooling operation, the first expansion valve 15 may be fully opened. The liquid refrigerant decompressed by the first expansion valve 15 is sent to the usage unit 3 via the liquid side closing valve 22 and the refrigerant pipe 1L.

  The low-pressure liquid refrigerant (or refrigerant in the gas-liquid two-phase state) sent to the usage unit 3 is further decompressed when passing through the usage-side expansion valve 17 and sent to the usage-side heat exchanger 16. The low-pressure gas-liquid two-phase refrigerant sent to the use-side heat exchanger 16 absorbs heat by performing heat exchange with room air, cools, and evaporates into a low-pressure gas refrigerant. The low-pressure gas refrigerant is sent to the heat source unit 2 via the refrigerant pipe 1V, and is sucked into the first and second compressors 11 and 12 via the gas-side closing valve 21 and the four-way valve 20.

<Heating operation>
In the heating operation of the air conditioner 1, the refrigerant discharged from the first and second compressors 11 and 12 is sent to the utilization unit 3 via the four-way valve 20, the gas side closing valve 21 and the refrigerant pipe 1V. The high-pressure gas refrigerant sent to the usage unit 3 exchanges heat with the outside indoor air in the usage-side heat exchanger 16 to dissipate heat, and is heated. By heat exchange in the use side heat exchanger 16, the high-pressure gas refrigerant dissipates heat and condenses to become a high-pressure liquid refrigerant. The high-pressure liquid refrigerant is depressurized according to the opening degree of the use side expansion valve 17 when passing through the use side expansion valve 17. The use side expansion valve 17 may be fully opened.

  The refrigerant that has passed through the use side expansion valve 17 is sent to the heat source unit 2 via the refrigerant pipe 1L. The liquid refrigerant sent to the heat source unit 2 is further depressurized according to the opening degree when passing through the first expansion valve 15 via the liquid side closing valve 22 and flows into the heat source side heat exchanger 13. The low-pressure gas-liquid two-phase refrigerant that has flowed into the heat source side heat exchanger 13 absorbs heat from outside air or water and evaporates. Thereby, the low-pressure gas-liquid two-phase refrigerant becomes a low-pressure gas refrigerant. The low-pressure gas refrigerant flowing out of the heat source side heat exchanger 13 is sucked into the first and second compressors 11 and 12 via the four-way valve 20.

<Branch refrigerant circuit 5>
The branch refrigerant circuit 5 is a circuit through which the refrigerant branched from the main refrigerant circuit 4 flows. The branch refrigerant circuit 5 cools the power elements 31 and 32 that generate heat.
The branch refrigerant circuit 5 is provided in the main refrigerant circuit between the heat source side heat exchanger 13 and the first expansion valve 15 of the main refrigerant circuit 4 and between the first expansion valve 15 and the liquid side closing valve 22. 4 in parallel. The branch refrigerant circuit 5 includes a cooling member 41 of the power element 31, a cooling member 42 of the power element 32, and a second expansion valve 43.

By using the second expansion valve 43, the branch refrigerant circuit 5 is put into a use state only when the power elements 31, 32 are cooled. On the other hand, when it is not necessary to cool the power elements 31, 32, the second expansion valve 43 is closed, and the branch refrigerant circuit 5 is set to an unused state.
The cooling member 41 is a member for cooling the power element 31 that generates heat and becomes high temperature. The cooling member 42 is a member for cooling the power element 32 that generates heat and becomes high temperature.

  During the cooling operation, a part of the refrigerant flowing through the main refrigerant circuit 4 is branched into the branch refrigerant circuit 5 from between the heat source side heat exchanger 13 and the first expansion valve 15. The branched refrigerant flows in the order of the second expansion valve 43, the cooling member 41, and the cooling member 42, and joins the main refrigerant circuit 4 between the first expansion valve 15 and the liquid side closing valve 22.

  On the other hand, during the heating operation, a part of the refrigerant flowing through the main refrigerant circuit 4 is branched into the branch refrigerant circuit 5 from between the liquid side closing valve 22 and the first expansion valve 15. In contrast to the cooling operation, the branched refrigerant flows in the order of the cooling member 42, the cooling member 41, and the second expansion valve 43, and at a position between the first expansion valve 15 and the heat source side heat exchanger 13. The main refrigerant circuit 4 is joined. That is, the refrigerant flow in the branch refrigerant circuit is reversed between the cooling operation and the heating operation.

  The refrigerant flow rate that flows through the branch refrigerant circuit 5 may be the same as the refrigerant flow rate that flows through the main refrigerant circuit 4, but may be smaller than the refrigerant flow rate that flows through the main refrigerant circuit 4. In the former case, since the cooling capacity of the cooling members 41 and 42 is increased, overheating of the power elements 31 and 32 can be suppressed. In the latter case, since the cooling capacity of the cooling members 41 and 42 is lowered, overcooling of the power elements 31 and 32 can be prevented. Thereby, it can suppress that dew condensation arises in the power elements 31 and 32 and its peripheral part.

  In the example of FIG. 1A, the power element 31 of the power elements 31 and 32 and the cooling member 41 of the cooling members 41 and 42 are provided in the vicinity of the second expansion valve 43. The member 42 may be provided in the vicinity of the second expansion valve 43.

<Discharged gas branch refrigerant circuit 6>
The discharge gas branch refrigerant circuit 6 is a circuit that heats the power elements 31 and 32 in order to suppress the dew of the power elements 31 and 32. In the discharge gas branch refrigerant circuit 6, the refrigerant branched from the discharge pipes 11t and 12t of the first and second compressors 11 and 12 flows.

The discharge gas branch refrigerant circuit 6 includes a main refrigerant circuit in a portion from between the first compressor 11 and the second compressor 12 and the four-way valve 20 to between the second expansion valve 43 and the cooling members 41 and 42. 4 in parallel.
The discharge gas branch refrigerant circuit 6 includes an electromagnetic valve 50 that switches the discharge gas branch refrigerant circuit 6 between a use state and an unused state.

  The solenoid valve 50 is closed in a normal state (steady state), and the discharge gas branch refrigerant circuit 6 is not used. When the solenoid valve 50 is opened, a part of the high-pressure and high-temperature gas refrigerant discharged from the first and second compressors 11 and 12 is discharged from between the first and second compressors 11 and 12 and the four-way valve 20. The refrigerant flows into the branch refrigerant circuit 6 and enters a use state, and joins the branch refrigerant circuit 5 between the second expansion valve 43 and the cooling members 41 and 42.

<Inverter device 30>
2A is a front view of a part of the inverter device 30, and FIG. 2B is a partial arrow view of the inverter device 30 in the A direction.
The inverter device 30 is a circuit that controls the power supply of the air conditioner 1, and the power elements 31 and 32 as constituent elements generate heat and become high temperature.

As shown in FIG. 2A, in the inverter device 30, power elements 31 and 32 are attached to one side of a printed board 33.
As shown in FIG. 2B, the cooling members 41 and 42 include refrigerant jackets 43a and 43b made of a metal having high thermal conductivity such as aluminum and copper, and refrigerant tubes 44 embedded in the refrigerant jackets 43a and 43b, respectively. ing. In the refrigerant pipe 44, the refrigerant branched from the main refrigerant circuit 4 flows through the branched refrigerant circuit 5 (see FIG. 1A). The cooling members 41 and 42 through which the refrigerant flows constitute a cooler.
In addition, as long as the refrigerant | coolant jackets 43a and 43b are materials with high heat conductivity, you may use materials other than a metal.

As shown in FIG. 2A, the refrigerant jackets 43a and 43b are formed in a slightly thick plate shape in order to increase the heat capacity. The refrigerant jackets 43a and 43b are attached to one side of the power elements 31 and 32, respectively.
That is, one surface 43a1, 43b1 of the refrigerant jackets 43a, 43b is in close contact with one surface of the power elements 31, 32, respectively. The refrigerant flowing through the refrigerant pipe 44 of the branch refrigerant circuit 5 absorbs heat from the power elements 31 and 32 via the refrigerant jackets 43a and 43b, respectively.

  The cooling members 41 and 42 include cooling unit temperature sensors 71a and 71b, respectively. The cooling unit temperature sensors 71a and 71b detect the temperatures on the surfaces of the refrigerant jackets 43a and 43b. Therefore, the cooling unit temperature sensors 71a and 71b are attached to one surface 43a1 and 43b1 in contact with the power elements 31 and 32 of the cooling members 41 and 42, respectively. The cooling part temperature sensors 71a and 71b may be provided inside the power elements 31 and 32, respectively, or may be provided on the surfaces of the power elements 31 and 32.

<Control system of air conditioner 1>
FIG. 3 is a diagram illustrating a control system of the air conditioner 1.
The control unit 60 controls the operation of the air conditioner 1 based on detection signals received from various sensors provided in the air conditioner 1. The control unit 60 may be provided in the heat source unit 2 or may be provided in the utilization unit 3. Moreover, the control part 60 may be provided separately for the heat source unit 2 and the utilization unit 3 according to function.

  The control unit 60 includes a microcomputer (not shown), for example. The control unit 60 includes first and second compressors 11 and 12 (power elements 31 and 32), a four-way valve 20, a first expansion valve 15, a second expansion valve 43, and an electromagnetic valve mounted on the heat source unit 2. 50, the blower 14, the use side expansion valve 17, and the blower 18 are controlled. At this time, the control unit 60 receives the measurement values of the cooling unit temperature sensors 71a and 71b installed in the cooling members 41 and 42 as control information.

<Control flow of air conditioner 1>
Hereinafter, a specific control flow of the air conditioner 1 will be described with reference to a control flowchart shown in FIG. FIG. 4 is a diagram illustrating a control flow of the air conditioner 1 according to the first embodiment.
The control flow of the air conditioner 1 is executed by, for example, a microcomputer mounted on the control unit 60 (see FIG. 3) provided in the heat source unit 2.
When the operation of the air conditioner 1 is started, in step S1, the control unit 60 detects the cooling unit temperatures of the refrigerant jackets 43a and 43b by the cooling unit temperature sensors 71a and 71b (FIG. 2A).

  Subsequently, in step S2, the control unit 60 opens the opening of the second expansion valve 43 of the branch refrigerant circuit 5 so that the cooling unit temperatures of the refrigerant jackets 43a and 43b detected in step S1 become the cooling unit target temperature. Adjust. Specifically, when each cooling part temperature of the refrigerant jackets 43a and 43b is higher than the cooling part target temperature, the second expansion valve 43 is opened to promote cooling, and the flow rate of the refrigerant flowing through the cooling members 41 and 42 Increase. On the other hand, when the cooling part temperature of the refrigerant jackets 43a and 43b is lower than the cooling part target temperature, the second expansion valve 43 is closed to reduce the flow rate of the refrigerant flowing through the cooling members 41 and 42. In the cooling operation, the refrigerant flows in the order of the second expansion valve 43, the cooling member 41, and the cooling member 42. In the heating operation, the refrigerant flows in the order of the cooling member 42, the cooling member 41, and the second expansion valve 43.

  Here, the cooling unit target temperature may be a fixed temperature. Further, since the required cooling capacity varies depending on the heat generation amount of the power elements 31 and 32, the temperature value may vary depending on the rotational speeds of the first and second compressors 11 and 12, the inverter current value, and the like. Moreover, the cooling capacity of the cooling members 41 and 42 which are coolers changes with the temperature of the refrigerant flowing through the cooling members 41 and 42. Therefore, the temperature value may vary depending on the temperature of the refrigerant flowing through the cooling members 41 and 42 shown in FIG. 2A and the temperature of the surrounding refrigerant. Note that the cooling target temperature is set higher than the condensation temperature described later in order to suppress the occurrence of condensation.

In step S <b> 3, the control unit 60 determines whether or not a dew generation condition that determines that dew condensation can occur on the power elements 31 and 32 or the peripheral members of the power elements 31 and 32 is satisfied.
If the dew condensation generation condition is not satisfied (NO in step S3), the control unit 60 proceeds to step S4. On the other hand, when the dew condensation generation condition is satisfied (YES in step S3), the control unit 60 proceeds to step S6.

  Here, whether or not the dew condensation generation condition is satisfied is determined based on whether or not the temperatures of the cooling unit temperature sensors 71a and 71b are lower than the dew condensation temperature. The dew condensation temperature may be a fixed temperature value, but considering that the dew point temperature varies depending on the ambient temperature of the power elements 31, 32 and the refrigerant jackets 43a, 43b, the surroundings of the power elements 31, 32 and the refrigerant jackets 43a, 43b. The temperature value may be varied depending on the temperature.

  In step S4, the control unit 60 determines whether or not the electromagnetic valve 50 is open. If the solenoid valve 50 is not open (NO in step S4), the control unit 60 returns to step S1. If the solenoid valve 50 is open (YES in step S4), the control unit 60 proceeds to step S5.

In step S5, the control unit 60 closes the solenoid valve 50, and then returns to step S1. That is, the solenoid valve is closed.
In step S6, the control unit 60 determines whether or not the electromagnetic valve 50 is closed. If the solenoid valve 50 is not closed (NO in step S6), the control unit 60 returns to step S1. When the solenoid valve 50 is closed (YES in step S6), the control unit 60 proceeds to step S7.

In step S7, the controller 60 opens the solenoid valve 50, and then returns to step S1.
As described above, when the plurality of power elements 31 and 32 are cooled by the cooling members 41 and 42, for example, the power element 31 corresponding to the operating first compressor 11 generates heat, while the second stopped element is stopped. The power element 32 corresponding to the compressor 12 does not generate heat. Even in such a case, since all the power elements 31 and 32 are cooled by the cooling members 41 and 42, the temperature of the power element 32 corresponding to the stopped second compressor 12 and its peripheral portion is below the dew point. May cause condensation.

  Further, even when the second expansion valve 43 is provided in the branch refrigerant circuit 5 and the cooling capacity of the cooling unit is controlled, all the power elements 31 and 32 are cooled by the cooling members 41 and 42, so that they are stopped. There is a possibility that the temperature of the power element 32 corresponding to the second compressor 12 and the surrounding area thereof will drop below the dew point and condensation will occur.

  Whether or not dew condensation occurs in the power elements 31 and 32 and its peripheral portion is determined by whether or not the temperature of the cooling members 41 and 42 is lower than the dew point temperature of the ambient temperature of the power elements 31 and 32 and the refrigerant jackets 43a and 43b. . In particular, as shown in FIG. 1B, when the heat source side heat exchanger 13 is a heat exchanger that exchanges heat between water and the refrigerant, the water temperature and the ambient temperature of the power elements 31, 32 and the refrigerant jackets 43a, 43b are Even if the water temperature is low, the ambient temperature of the power elements 31, 32 and the refrigerant jackets 43a, 43b may be high.

  When the water temperature is low, the temperature of the refrigerant flowing through the cooling members 41 and 42 also decreases. In this case, if the ambient temperature of the power elements 31 and 32 and the refrigerant jackets 43a and 43b is high, dew condensation occurs in the power elements 31 and 32 and its peripheral portion. Is more likely to occur.

  Here, when the solenoid valve 50 is opened, a part of the high-pressure and high-temperature gas refrigerant discharged from the first and second compressors 11 and 12 is transferred between the first and second compressors 11 and 12 and the four-way valve 20. Flows into the discharge gas branch refrigerant circuit 6 and joins the branch refrigerant circuit 5 between the second expansion valve 43 and the cooling members 41, 42.

When the temperature of the cooling members 41 and 42 is lower than the dew condensation temperature, the control unit 60 controls the second expansion valve 43 in the branch refrigerant circuit 5 to close, so the flow rate of refrigerant flowing through the second expansion valve 43 decreases.
Therefore, in the case of the cooling operation, most of the refrigerant joined to the branch refrigerant circuit 5 flows in the order of the cooling member 41 and the cooling member 42, and between the first expansion valve 15 and the liquid side closing valve 22, the main refrigerant circuit 4. To join.

On the other hand, in the case of heating operation as well, by closing the second expansion valve 43, most of the refrigerant joined to the branch refrigerant circuit 5 flows in the order of the cooling member 41 and the cooling member 42, and the first expansion valve 15 and the liquid The main refrigerant circuit 4 merges with the side closing valve 22.
For this reason, the refrigerant from the discharge gas branch refrigerant circuit 6 can raise the temperature of the cooling members 41 and 42 that are lower than the dew condensation temperature, thereby preventing the dew condensation from occurring in the power elements 31 and 32 and the vicinity thereof. It becomes possible.

  Further, even when both the first and second compressors 11 and 12 are in operation, if the temperature of the cooling members 41 and 42 is lower than the dew condensation temperature, the temperature of the cooling members 41 and 42 is increased to increase the temperature. The valve 50 can be opened to raise the temperature.

  As described above, the air conditioner 1 includes the main refrigerant circuit 4 and the branch refrigerant circuit 5. The main refrigerant circuit 4 includes first and second compressors 11 and 12, a heat source side heat exchanger 13, a first expansion valve 15, and a use side heat exchanger 16, and the refrigerant flows. The branch refrigerant circuit 5 includes a pipe of a discharge gas branch refrigerant circuit 6 through which a part of the refrigerant discharged from the first and second compressors 11 and 12 flows, and the refrigerant branched from the main refrigerant circuit 4 flows.

  In the air conditioner 1, by flowing the high-temperature refrigerant discharged from the first and second compressors 11 and 12 to the branch refrigerant circuit 5 of the sub refrigerant circuit, the refrigerant temperature flowing through the cooling members 41 and 42 can be increased, It is possible to keep the temperature of the surfaces of the power elements 31 and 32 and the periphery thereof higher than the dew point temperature of the ambient air. For this reason, it is possible to suppress the dew from being attached to the plurality of power elements 31 and 32 and the periphery thereof.

  In addition, the flow rate of the refrigerant flowing through the branch refrigerant circuit 5 of the sub refrigerant circuit is made smaller than the flow rate of the refrigerant flowing through the main refrigerant circuit 4, thereby suppressing deterioration in performance of the cooling operation and heating operation. Dew can be suppressed.

<< Second Embodiment >>
In FIG. 5, the control flowchart of the air conditioner 1 of 2nd Embodiment is shown.
When the solenoid valve 50 of the discharge gas branch refrigerant circuit 6 is opened and the refrigerant flows from the main refrigerant circuit 4 to the branch refrigerant circuit 5, the amount of refrigerant in the main refrigerant circuit 4 decreases, which affects the cooling capacity and heating capacity.
Therefore, in the second embodiment, the opening of the electromagnetic valve 50 is suppressed to suppress a decrease in cooling capacity and heating capacity.

Since the control flow of the second embodiment is partially the same as the control flow of the second embodiment shown in FIG. 4, only the control different from the first embodiment will be described.
Unlike the first embodiment, in the second embodiment, when the dew condensation generation condition is satisfied in step S3 (YES in step S3), the control unit 60 proceeds to step S8 (FIG. 5).

  In step S8, the control unit 60 determines whether the second expansion valve 43 is fully closed. This is because, even if the second expansion valve 43 is fully closed, the electromagnetic valve 50 is opened and the discharge gas branch refrigerant circuit 6 is opened only for the purpose of preventing condensation only when the temperature of the power elements 31 and 32 does not rise. It is for use.

If the second expansion valve 43 is not fully closed (NO in step S8), the process returns to step S1 because there is room for reducing the opening of the second expansion valve 43.
If the second expansion valve 43 is fully closed (YES in step S8), there is no room for reducing the opening of the second expansion valve 43, and the process proceeds to step S6.

  As described above, when part of the gas refrigerant discharged from the first and second compressors 11 and 12 flows through the discharge gas branch refrigerant circuit 6 by opening the electromagnetic valve 50, the heat source side heat exchanger is used during cooling operation. The refrigerant | coolant flow volume which flows through 13 reduces, and a cooling capacity falls, and the heating capacity | capacitance falls by the refrigerant | coolant flow volume which flows through the utilization side heat exchanger 16 at the time of heating operation decreasing. Therefore, it is better to reduce the excessive opening and closing of the electromagnetic valve 50.

  As described in the first embodiment, when the temperature of the cooling members 41 and 42 is lower than the dew condensation temperature, the control unit 60 controls the second expansion valve 43 in the closing direction, and thus the refrigerant flow rate flowing through the second expansion valve 43. Will be less. Therefore, in the second embodiment, even if the second expansion valve 43 is closed and the flow rate of the refrigerant flowing through the cooling members 41 and 42 decreases and the cooling capacity of the cooler decreases, the temperature of the cooling members 41 and 42 is the dew condensation temperature. The solenoid valve 50 is opened only when it is less than.

In step S6, the control unit 60 determines whether or not the electromagnetic valve 50 is closed.
If the solenoid valve 50 is not closed, that is, if the solenoid valve 50 is open (NO in step S6), the process returns to step S1.
When the solenoid valve 50 is closed (YES in step S6), the process proceeds to step S7, and the control unit 60 opens the solenoid valve 50. Thereafter, the control unit 60 returns to Step S1.

  By the above control, excessive opening and closing of the electromagnetic valve 50 can be suppressed. By suppressing the excessive opening and closing of the solenoid valve 50, it is possible to suppress a decrease in cooling capacity and heating capacity when the discharge gas branch refrigerant circuit 6 is used.

<< Third Embodiment >>
FIG. 6 is a diagram illustrating an example of the refrigeration cycle of the air conditioner 1 according to the third embodiment.
In the first embodiment shown in FIG. 1A, a refrigerant circuit in which a plurality of first and second compressors 11 and 12, a plurality of power elements 31 and 32, and a plurality of cooling members 41 and 42 are provided in the heat source unit 2 is provided. Although illustrated, it is not restricted to this. As shown in FIG. 6, a refrigerant circuit in which a single compressor 11, a single power element 31, and a single cooling member 41 are provided in the heat source unit 2 may be used. In FIG. 6, an expansion valve 51 is used instead of the electromagnetic valve 50. By controlling the opening degree of the expansion valve 51, the ratio of the refrigerant flow rate flowing from the gas refrigerant discharged from the compressor 11 to the branch refrigerant circuit 6 can be adjusted.

FIG. 7 is a diagram illustrating another example of the refrigeration cycle of the air conditioner 1 according to the third embodiment.
As shown in FIG. 7, the discharge gas branching refrigerant circuit 6 may include a plurality of electromagnetic valves 50 and 52. By opening and closing the plurality of solenoid valves 50 and 52, the ratio of the refrigerant flow rate flowing from the gas refrigerant discharged from the compressor 11 to the branch refrigerant circuit 6 can be finely adjusted, that is, finely adjusted.

<< Fourth Embodiment >>
In the embodiment shown in FIG. 1A, the discharge gas branch refrigerant circuit 6 branches from the first compressor 11 and the second compressor 12 of the main refrigerant circuit 4 and between the four-way valve 20, and the second expansion valve 43 and the cooling circuit. Although it joins between the members 41 and 42, it is not restricted to this.
FIG. 8 is a diagram illustrating an example of the refrigeration cycle of the air conditioner 1 according to the fourth embodiment.

  In the fourth embodiment, the discharge gas branch refrigerant circuit 6 has a configuration in which the cooling member 41 flows in parallel with the branch refrigerant circuit 5 through the pipe 6 a and joins between the first expansion valve 15 and the liquid side shut-off valve 22. is there. In the fourth embodiment, when the electromagnetic valve 50 is opened, a part of the high-pressure and high-temperature gas refrigerant discharged from the compressor 11 flows from between the compressor 11 and the four-way valve 20 to the discharge gas branch refrigerant circuit 6. Then, it flows through the cooling member 41 of the branch refrigerant circuit 5 and joins the main refrigerant circuit 4 between the first expansion valve 15 and the liquid side closing valve 22.

As a result, the high-pressure gas from the discharge gas branch refrigerant circuit 6 can flow to the cooling member 41 without affecting the opening and closing of the second expansion valve 43.
Also in this case, since the refrigerant from the discharge gas branch refrigerant circuit 6 flows through the cooling member 41, the cooling part temperature (temperature of the cooling member 41 and the power element 31) can be raised. Therefore, it is possible to suppress the occurrence of condensation on the power element 31 and its surroundings.

<< Modified form >>
In the first embodiment described above, the cooling members 41 and 42 shown in FIGS. 2A and 2B are exemplified, but the present invention is not limited to this. FIG. 9A to FIG. 9D are schematic views showing modified examples 1 to 4 of the cooling members 41 and 42 of the first embodiment, respectively. In addition, the arrow in FIG. 9A-FIG. 9D shows the flow of a refrigerant | coolant.

In the first modification shown in FIG. 9A, the pipe 80 constituting the branch refrigerant circuit 5 flows in the order of the cooling member 42 that cools the power element 32, the cooling member 41 that cools the power element 31, the cooling member 41, and the cooling member 42.
In the second modification shown in FIG. 9B, the cooling members 41 and 42 are replaced with a single refrigerant jacket 45 that cools the power element 31 and the power element 32.

  In Modification 3 shown in FIG. 9C, the cooling member 41 is a refrigerant jacket that cools the power element 31, and the cooling member 42 is a refrigerant jacket 42 that cools the power element 32. The refrigerant jacket 41 is attached to a part of the cooling unit 80 a of the refrigerant pipe 80. The refrigerant jacket 42 is attached to a part of the cooling section 80 b of the refrigerant pipe 80. In the third modification, the cooling unit 80a and the cooling unit 80b are connected in parallel to the upstream and downstream piping 80.

  In the fourth modification shown in FIG. 9D, the cooling parts 80a and 80b are not bent into a U-shape as in the first to fourth embodiments and the first to third modifications, but extend substantially linearly. .

<< Other Embodiments >>
1. In the above-described embodiment, the power elements 31 and 32 are exemplified as the heating element to be cooled. However, the heating element may be other than the power elements 31 and 32 as long as it generates heat.

2. In addition, this invention is not limited to the said embodiment and modification, Various modifications are included. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of the embodiment.

1 Air conditioner 4 Main refrigerant circuit 5 Sub refrigerant circuit (branch refrigerant circuit)
6 Piping 6a Piping 11 First compressor (compressor)
12 Second compressor (compressor)
13 heat source side heat exchanger 15 first expansion valve 16 use side heat exchanger 31 power element (heating element, first heating element)
32 Power element (heating element, second heating element)
41, 42 Cooling member 43 Second expansion valve 60 Control unit

Claims (2)

A main refrigerant circuit in which a compressor, a heat source side heat exchanger, a first expansion valve, and a use side heat exchanger are provided and the refrigerant flows;
A cooling member through which the refrigerant branched from the main refrigerant circuit flows, and a sub refrigerant circuit through which the refrigerant branched from the main refrigerant circuit flows;
A heating element cooled by the cooling member,
A pipe through which a part of the refrigerant discharged from the compressor flows is connected to a pipe between the cooling member and a second expansion valve that is provided in the sub refrigerant circuit and expands the refrigerant flowing to the cooling member. An air conditioner characterized by that. A main refrigerant circuit in which a compressor, a heat source side heat exchanger, a first expansion valve, and a use side heat exchanger are provided and the refrigerant flows;
A cooling member through which the refrigerant branched from the main refrigerant circuit flows, and a sub refrigerant circuit through which the refrigerant branched from the main refrigerant circuit flows;
A heating element cooled by the cooling member;
A pipe provided in parallel to the sub refrigerant circuit, connected to a pipe provided in the cooling member and flowing a part of the refrigerant discharged from the compressor to the pipe provided in the cooling member, and the cooling member An air conditioner comprising: a pipe through which the refrigerant that has passed through the pipe flows into the main refrigerant circuit.

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